MODIFIED DIENE-CONTAINING (CO)POLYMER, METHOD FOR PREPARING THEREOF AND USE OF THE SAME AS FLAME RETARDANT

Field of the invention

The invention relates to the field of modified diene-containing (co)polymers, in particular, modified styrene-butadiene copolymer that can be used as a flame retardant for polymer compositions based on expandable polystyrene. In particular, the invention relates to a modified diene-containing (co)polymer, a method for preparing thereof and the use of the same as a flame retardant for polystyrene, including expandable polystyrene.

Background of the invention

Flame retardants are widely used in products made of various polymers and polymer compositions, for example products based on expandable polystyrene, to provide them with flame retardant properties [Stockholm Convention on Persistent Organic Pollutions, UNEP/POPS/POPRC.6/10, 15.10.2010]. Such polymer compositions usually contain various low-molecular weight brominated compounds, for example hexabromocyclododecane (HBCD), used as flame retardants. However, the results of many studies have shown that HBCD has a tendency to bioaccumulation and is highly toxic and resistant to environmental factors [Stockholm Convention on Persistent Organic Pollutions, UNEP/POPS/POPRC.6/10, 15.10.2010, cl.4]. This has resulted in limited use of HBCD as a flame retardant in order to reduce ecological risks.

Processing temperatures for some polymer compositions, for example based on expandable polystyrene [Stockholm Convention on Persistent Organic Pollutions, UNEP/POPS/POPRC.6/10, 15.10.2010, cl.47], are often very high and can result in degradation of a flame retardant during processing a polymer composition. In this case, loss of flame retardant properties in polymer compositions and the formation of decomposition products, such as HBr, are observed. Therefore, it is important that a flame retardant was thermally stable at processing temperatures of polymer materials and also met the requirements of non-toxicity and environmental compatibility.

As an alternative to HBCD, in the prior art there are known flame retardants more ecological compared to HBCD, prepared on the basis of diene-containing (co)polymers, in particular, styrene-butadiene copolymers.

Examples of such flame retardants, such as, for example, brominated styrene- butadiene copolymers, are known in the prior art as presented by application W02008021417 and patent RU2414479.

In particular, patent RU2414479 describes a heat resistant brominated styrene- butadiene copolymer that can be used as a flame retardant in expandable and non- expandable polymer materials. Said brominated styrene-butadiene copolymer is characterized by the content of non-brominated non-aromatic double bonds that is less than or equal to 15% based on the content of non-aromatic double bonds in the copolymer before bromination, as determined by 'H NMR-spectroscopy and a 5% weight loss temperature of at least 200°C, as determined by thermogravimetric analysis (TGA).

Patent RU2414479 also provides a method for preparing the above-mentioned heat resistant brominated copolymer, the method comprises:

a) providing a homogenous reaction solution of a copolymer, a brominating agent, in particular tetraalkylammonium tribromide, and a solvent;

b) aging the reaction solution under reaction conditions for a time sufficient for bromination of at least 85% of non-aromatic double bonds comprised in the copolymer; c) isolating the brominated copolymer by passing a filtrate through a silica gel or ion-exchange resin layer;

d) washing the filtrate with an aqueous solution of sodium hydrogen sulfite to neutralize a non-reacted brominating agent; and

e) isolating a brominated copolymer by precipitation in methanol.

In addition, RU2414479 provides a polymer mixture comprising said heat resistant brominated styrene-butadiene copolymer and a molded article comprising said polymer mixture.

This flame retardant possesses low thermal stability at high processing temperatures for expandable polystyrene and a limited compatibility of highly brominated styrene-butadiene copolymers, which can cause difficulties in obtaining a homogeneous structure of expanded polystyrene at large thicknesses of products made thereof.

In addition, patent RU2530021 describes the use of a brominated and epoxidated styrene-butadiene copolymer as a flame retardant for expandable polystyrene.

According to the technical solution described in RU2530021, the flame retardant is prepared by a method comprising:

a) epoxidizing a starting styrene-butadiene copolymer having a molecular weight of at least 700 g/mol so that at least part of non-conjugated carbon-carbon double bonds is subjected to epoxidation; and

b) brominating at least a part of the remaining non-conjugated carbon-carbon double bonds by contacting the styrene-butadiene copolymer epoxidated in step a) with quaternary ammonium tribromide to obtain a brominated and epoxidated styrene- butadiene copolymer.

The flame retardant prepared according to RU2530021 is characterized by a molecular weight of at least 1500 g/mol, a bromine content of at least 35 wt.%, and a 5% weight loss temperature of at least 180°C.

However, despite the fact that said flame retardant contains epoxy groups capable of absorbing HBr that releases at high processing temperatures of polymer compositions based on expandable polystyrene, such a flame retardant has a low compatibility with polystyrene.

The closest technical solution to the claimed flame retardant and method for preparing thereof is a hydroxybrominated styrene-butadiene copolymer according to application WO2016123263 (prototype), wherein said copolymer is used as a flame retardant for expandable polystyrene.

The flame retardant according to application WO2016123263 is prepared by reacting a styrene-butadiene copolymer with quaternary ammonium tribromide to brominate from 50 to 98% of repeating butadiene units in the starting copolymer, thus obtaining a partially brominated copolymer, followed by reaction of the partially brominated copolymer with N-haloimide, for example N-chlorosuccinimide or N- bromosuccinimide, in the presence of water and a water-miscible solvent to provide halohydration of a part of repeating butadiene units, thus obtaining hydroxybrominated styrene-butadiene copolymer. The resulting hydroxybrominated styrene-butadiene copolymer comprises from 2 to 50 wt.% of butadiene units, which are hydroxybrominated, and from 50 to 98 wt.% of butadiene units, which are brominated, and has a 5% weight loss temperature of at least 200°C.

The described flame retardant has a high content of hydroxyl groups in its structure, which leads to a significant increase in the polarity of the flame retardant molecule, which in turn deteriorates the stability of the system during the preparation of polystyrene, thereby deteriorating the polystyrene particle size distribution.

In addition, the method for preparing a flame retardant according to said invention is characterized by large amount of time spent in the step of preparing hydroxybrominated styrene-butadiene copolymer, and in the step of its isolation from the reaction mass, and the need to use expensive reagents, in particular, N-haloimide.

However, despite the fact that the prior art method for preparing brominated flame retardants involves the use, in particular, of halosuccinimides, it is evident that this method results in the formation of HBr relatively easily released upon heating of hydroxybrominated units, which leads to decomposition of the flame retardant and, as a consequence, to coloration of polystyrene compositions, including expandable polystyrene.

Thus, the prior art flame retardants based on diene-containing (co)polymers and methods for preparing thereof are not efficient enough and also require large economic and time costs.

In this connection, a prospective direction is the development of a flame retardant based on diene-containing (co)polymer that will be heat resistant, will meet ecological requirements, and will not affect the polymerization process and the formation of polystyrene granules, while exhibiting good compatibility with and conferring excellent flame retardant properties to polystyrene, including expandable polystyrene.

Summary of the invention

The present invention is aimed at developing a modified diene-containing (co)polymer that can be used as a flame retardant for expandable polystyrene, and a method for preparing thereof.

The technical result of the present invention is the preparation of a modified diene-containing (co)polymer characterized by a high heat resistance, in particular, a 5% weight loss temperature of at least 180°C, a molecular weight of at least 1500 g/mol, and a halogen content of at least 35 wt.% based on the total weight of (co)polymer, wherein the (co)polymer does not affect the polymerization process and the formation of polystyrene granules.

This technical result is achieved by preparation of a modified diene-containing (co)polymer comprising acyloxyhalogenated units (units that comprise halogen atoms and an acyloxy group) in an amount of from 0.01 to 10 wt.% based on the total weight of (co)polymer, and halogen atoms in an amount of at least 35 wt.% based on the total weight of (co)polymer.

The authors of the present invention have unexpectedly found that said modified diene-containing (co)polymer can be obtained by using as a modifying system a mixture of a carboxylic acid and a halogenating agent to introduce acyloxyhalogenated groups into the structure of the (co)polymer, and an additional halogenating agent to introduce an additional amount of halogen atoms into the structure of the (co)polymer.

In addition, the authors of the present invention have found that the modified diene-containing (co)polymer according to the invention can be prepared by reacting hydroxyhalogenated diene-containing (co)polymers, for example, prepared according to application WO2016123263, with components of an acylating system.

The authors of the present invention have also found that a modified diene- containing (co)polymer comprising acyloxyhalogenated diene units is heat resistant, does not affect the polymerization process and the formation of polystyrene granules, is well compatible with polystyrene, and provide expandable polystyrene with high flame retardant properties.

It is suggested that the presence of acyloxyhalogenated units allows to achieve the balance between hydrophilic and hydrophobic properties in the modified diene- containing (co)polymer molecule, thereby ensuring the stability of the entire system during the process of polystyrene preparation, while not affecting the formation of polystyrene granules and providing expandable polystyrene with high flameretardant properties.

The present invention makes it possible to obtain a modified diene-containing (co)polymer comprising acyloxyhalogenated diene units and halogen atoms, wherein the (co)polymer can be used as a flame retardant in various polymer compositions, for example, based on polystyrene, including expandable polystyrene.

Description of drawings

The technical solutions disclosing the essence of the present invention is explained by referring to Figures 1 to 4.

Fig. 1 is a flowchart demonstrating the sequence of steps for preparing a modified diene-containing (co)polymer according to the present invention through step b) of modification.

Fig. 2 is a flowchart demonstrating the sequence of steps for preparing a modified diene-containing (co)polymer according to the present invention through step b) of partial halogenation.

Fig. 3 is a flowchart demonstrating the sequence of steps for preparing a modified diene-containing (co)polymer according to the present invention from hydroxyhalogenated diene-containing (co)polymer.

Fig.4 shows the 'H NMR spectrum of the resulting modified diene-containing (co)polymer comprising acyloxyhalogenated diene units and halogen atoms.

Description of the invention

According to the present invention, the claimed modified diene-containing (co)polymer is a heat-resistant modified diene-containing (co)polymer that is characterized by a weight-average molecular weight of at least 1500 g/mol, preferably from 2000 to 280000 g/mol, more preferably from 10000 to 150000 g/mol, most preferably from 60000 to 100000 g/mol and by the presence of multiple non-conjugated carbon-carbon double bonds, wherein at least two of them (but less than all non- conjugated carbon-carbon double bonds) are subjected to modification and wherein the modified diene-containing (co)polymer comprises at least 35 wt.%, preferably at least 60 wt.%, more preferably at least 75 wt.% halogen based on the total weight of (co)polymer, and at least one acyloxyhalogenated non-conjugated carbon-carbon double bond.

The term "heat resistance" as used herein is a 5% weight loss temperature of a modified diene-containing (co)polymer, as measured by thermo gravimetric analysis (TGA) described below.

The heat-resistant modified diene-containing (co)polymer according to the present invention comprises acyloxyhalogenated diene units in an amount of from 0.01 to 10 wt.%, preferably from 0.1 to 5 wt.%, more preferably from 1 to 3 wt.% based on the total weight of (co)polymer.

Said acyloxyhalogenated diene units are, in particular, acyloxybrominated diene units.

In accordance with the invention, the 5% weight loss temperature of the modified diene-containing (co)polymer is at least 180°C, preferably at least 220°C, and more preferably at least 230°C.

An example of the modified diene-containing (co)polymer according to the present invention is, but is not limited to, a modified diene-containing (co)polymer of general formula (1):

group comprising 1 to 6 carbon atoms, for example an alkyl group, Hal is halogen selected from chlorine, bromine and iodine; k, 1, m, and n can be the same or different and preferably 20<k<900, 1<1<200, 40<(m+n)<4500, more preferably 40<k<400, 2<1<100, 100<(m+n)<2000, most preferably 150<k<250, 3<1<20, 700<(m+n)<1000. In addition, the order of units in the polymer chain can randomly vary.

The halogen in the structure of the modified diene-containing (co)polymer is chlorine, bromine, or iodine. Bromine atoms are preferred as the halogen atom in the modified diene-containing (co)polymer.

According to the present invention, the modified diene-containing (co)polymer is prepared by using a modifying system, which is a mixture of a carboxylic acid and a halogenating agent.

Starting diene-containing copolymers can be polymers and copolymers of conjugated dienes.

In the context of the present invention, an organic solvent is such a solvent that is liquid and inert under conditions of the process steps for preparing the modified diene-containing (co)polymer.

Another aspect of the present invention provides a method for preparing a modified diene-containing (co)polymer, comprising the steps of:

a) a step of dissolution, comprising optionally pre-grinding of a starting diene- containing (co)polymer, followed by dissolution in a solvent;

b) a step of modification, comprising adding components of a modifying system to the solution of the starting diene-containing (co)polymer in the solvent, as prepared in step a), to obtain an acyloxyhalogenated diene-containing (co)polymer;

c) a step of washing and separation in which water is added to the reaction mass obtained in step b) with subsequent separation of an aqueous and an organic layer;

d) an optional step of isolation, comprising precipitating or degassing the acyloxyhalogenated diene-containing (co)polymer from the organic layer obtained in step c);

e) an optional step of filtration and subsequent drying of the isolated acyloxyhalogenated diene-containing (co)polymer;

f) an optional step of dissolution, the step comprising pre-grinding the acyloxyhalogenated diene-containing (co)polymer, followed by dissolution in a solvent; g) a step of halogenation of the acyloxyhalogenated diene-containing (co)polymer, comprising adding a halogenating agent and optionally an aliphatic alcohol to the solution of step f);

h) a step of neutralization and separation, the step comprising adding an aqueous solution of a neutralizing agent to the reaction mass obtained in step g) and separating an aqueous and an organic layer;

i) a step of isolation, comprising precipitating or degassing the modified diene- containing (co)polymer from the organic layer obtained in step h);

j) a step of filtration and subsequent drying of the isolated modified diene- containing (co)polymer,

wherein the method is characterized in that the modifying system in step b) of modification is a carboxylic acid and a halogenating agent in a molar ratio of the carboxylic acid to the halogenating agent of from 1 :1 to 1000:1, preferably from 1 :1 to 100:1, more preferably from 1 :1 to 10:1.

Step a) of dissolution

In step a), a starting diene-containing (co)polymer is optionally pre-ground, followed by dissolution in an organic solvent with stirring.

The starting diene-containing (co)polymer can be a polymer or copolymer of a conjugated diene.

Suitable conjugated dienes are conjugated dienes comprising 4 to 12 carbon atoms, for example, selected from the group consisting of 1,3 -butadiene, 2-methyl- 1,3- butadiene (isoprene), 2-ethyl- 1,3 -butadiene, 2,3-di(Ci-C ₅ alkyl)- 1,3 -butadienes, such as 2, 3-dimethyl- 1,3-butadiene, 2, 3-diethyl-l, 3-butadiene, 2-methyl-3 -ethyl- 1,3 -butadiene, 2-methyl-3 -isopropyl- 1,3-butadiene, phenyl- 1,3 -butadiene, 1,3-pentadiene, 2,4- hexadiene, 2-methyl-pentadiene, 4-methyl-pentadiene, or mixtures thereof. 1 ,3- butadiene or isoprene are preferable.

Suitable comonomers in the starting diene-containing (co)polymer are vinylaromatic compounds, such as those selected from the group consisting of styrene, a-methylstyrene, ortho-, meta-, and para-methylstyrene, 3-vinyltoluene, ethylvinylbenzene, 4-cyclohexylstyrene, para-/er/-butylstyrene, methoxystyrenes, vinyl mesitylene, divinylbenzene, 1-vinylnaphthalene, 2,4,6-trimethylstyrene, or mixtures thereof. Styrene or a-methyl styrene are preferable.

Suitable polymers and copolymers of a conjugated diene comprise at least 30 wt.%, preferably at least 50 wt.%, more preferably 70 wt.% of polymerized conjugated diene units.

Such (co)polymers as butadiene polymer, styrene-butadiene copolymer, and styrene-butadiene-isoprene copolymer, wherein it is preferable to use a styrene- butadiene copolymer, which can be di- and tri-block copolymers of butadiene and styrene, are preferable as a starting diene-containing (co)polymer.

Examples of commercially available diene-containing (co)polymers are, but are not limited to, butadiene polymers with trade names BR-1243 Nd, grade B (LP), BR- 1243 Nd, grade B, and BR-1243 ND HV, styrene-butadiene block copolymers with trade namesDST R 30-00, SBS L 30-01 A, SBS R 30-00A, DST L 30-01, and DST L 30-01 (SR), and styrene-butadiene copolymer prepared by the solution polymerization method, with trade namesDSSK-2560-M27 (grade AA), DSSK-2560-M27 BB (grade A), and DSSK-4040-M27 (grade A), produced by PJC "SIBUR-Holding".

Suitable starting diene-containing (co)polymers have a weight-average molecular weight of at least 700 g/mol, preferably from 1000 to 400000 g/mol, more preferably from 2000 to 300000 g/mol, more preferably from 5000 to 200000 g/mol, more preferably from 20000 to 120000 g/mol, and most preferably from 20000 to 50000 g/mol, with a polydispersity index of 0.8 to 3, more preferably from 1 to 1.8, and most preferably from 1.1 to 1.5, and with the number of 1,2-units of at least 10 to 100 wt.%, preferably from 50 to 99 wt.%, more preferably from 60 to 80 wt.% per the polybutadiene part of (co)polymer.

The grinding, if necessary, of the starting diene-containing (co)polymer is performed by any method known from the art, for example, by using grinders, such as knife, hummer, and rotor grinders, fluid, and screw millers, and the like equipment.

Upon dissolving, the starting diene-containing (co)polymer is stirred by any method known from the art, for example, by using a device equipped with a mixer or a static mixer at a temperature of 10 to 50°C, preferably 15 to 40°C, more preferably 20 to 30°C.

Suitable solvents are, but are not limited to, organic solvents, preferably having a purity of 99% and more, which are ethers, for example, tetrahydrofuran, halogenated saturated aliphatic hydrocarbons, for example, carbon tetrachloride, chloroform, dibromomethane, dichloromethane, 1,2-dichloroethane; cycloaliphatic hydrocarbons, for example, cyclohexane; aromatic hydrocarbons, for example, toluene; halogenated aromatic hydrocarbons, for example, bromobenzene, chlorobenzene, and dichlorobenzene. Preferred organic solvents are those that are liquid under the conditions of modification of the starting diene-containing (co)polymer and that are inert under the conditions of step b) of modification of the starting diene-containing (co)polymer. Preferably, tetrahydrofuran, chloroform, dichloromethane, dichloroethane, cyclohexane, and toluene are used as the solvent, wherein tetrahydrofuran, chloroform, and dichloromethane are most preferable.

The weight ratio of the organic solvent to the starting diene-containing (co)polymer is from 5:1 to 30:1, preferably 8:1 to 20:1, and more preferably from 10:1 to 15:1.

The time of the dissolution process is at most 60 min, in particular, at most 50 min, at most 40 min, at most 30 min, at most 25 min, at most 20 min, at most 15 min, at most 13 min, at most 11 min, at most 9 min, at most 7 min, at most 5 min.

The mass obtained in the above-mentioned step a) of dissolution is a solution of the starting diene-containing (co)polymer in the organic solvent.

Step b) of modification

In step b) of modification, components of a modifying system are added to the solution of the starting diene-containing (co)polymer, obtained in step a).

According to the present invention, the modifying system is a carboxylic acid and a halogenating agent in a molar ratio of the carboxylic acid to the halogenating agent of from 1 :1 to 1000:1, preferably from 1 :1 to 100:1, more preferably from 1 :1 to 10:1.

The halogen in the halogenating agent is chlorine, bromine, or iodine. However, a preferred halogen in the halogenating agent in step b) is bromine.

The halogenating agent is, but is not limited to, bromoimide, for example, N- bromosuccinimide, N-bromophthalimide; or bromoamide, for example, N- bromoacetamide, or bromourea, for example, tetrabromoglycoluril, as such or as solutions in solvents with a concentration of 1% to 50%.

The acids used as the carboxylic acid are, but are not limited to, Ci-Cs alkylcarboxylic acids, for example, acetic acid, propionic acid, 2-ethylhexanoic acid; halogen-containing Ci-Cs acids, for example, bromoacetic acid, 2-bromopropionic acid; C ₆ -C ₈ alkylcarboxylic acids, for example, benzoic acid, 4-methylbenzoic acid; halogen- substituted C ₆ -C ₈ arylcarboxylic acids, for example, 4-bromobenzoic acid, or combinations thereof. Acetic acid, propionic acid, bromoacetic acid, benzoic acid, or 4- bromobenzoic acid are preferred as the carboxylic acid. The presence of additional halogen atoms in the acid allows further improvement of flame-retardant properties of the modified diene-containing (co)polymer.

The molar ratio of the halogenating agent to double bonds in the starting diene- containing (co)polymer in step b) is from 0.001:1 to 0.1 :1, more preferably from 0.01 :1 to 0.05:1, most preferably from 0.01 :1 to 0.02:1.

The addition of components of the modifying system to the solution of the starting diene-containing (co)polymer obtained in step a) can be in any order. Preferably, carboxylic acid is added first to the solution of the starting diene-containing (co)polymer, followed by addition of the halogenating agent.

The organic solvent used to dissolve the halogenating agent is selected from ether, for example, tetrahydrofuran; halogenated saturated aliphatic hydrocarbons, for example, chloroform, dibromomethane, dichloromethane, 1,2-dichloroethane; cycloaliphatic hydrocarbons, for example, cyclohexane; aromatic hydrocarbons, for example, toluene; halogenated aromatic hydrocarbons, for example, bromobenzene, chlorobenzene, and dichlorobenzene, or mixtures thereof, preferably having a purity of 99% and more. The halogenating agent is preferably added in the form of its solution in the solvent that was used in step a) to dissolve the starting diene-containing (co)polymer.

Step b) of modification is carried out in any batch or continuous process equipment known from the art. Suitable equipment is, but is not limited to, a continuous stirred tank reactor, a batch stirred tank reactor, autoclave with a mixer, which are designed to work with highly corrosive environments.

Preferably, step b) of modification of the starting diene-containing (co)polymer is carried out without exposure to light, for example, by carrying out the modification process in dark glass vessels, by wrapping the reactor with foil, or in a metal reactor to reduce the possibility of non-selective photocatalytic halogenation reactions.

The modification step is carried out at a temperature of 0 to 100°C, preferably 20 to 80°C, and more preferably 40 to 60°C, and under atmospheric pressure.

The rate of stirring the reaction mass after addition of the modifying system is from 50 to 600 rpm, preferably from 100 to 500 rpm, more preferably from 200 to 300 rpm.

The modification step b) can be carried out for any time sufficient to achieve a desired modification degree of the starting diene-containing (co)polymer, as disclosed above. Preferably, the time of modification is at least 15 min, at least 20 min, at least 25 min, at least 30 min, at least 45 min, at least 60 min, at least 120 min.

The mass obtained after step b) of modification comprises an acyloxyhalogenated diene-containing (co)polymer having an acyloxyhalogenation degree of at least 0.01%, preferably at least 0.1%, most preferably 1%.

Additional steps c) of washing and separation, d) of isolation, and e) of filtration and subsequent drying are carried out in order to completely remove residues of the modifying system, which in the subsequent step of halogenation lead to undesirable side reactions.

Step c) washing and separation

Step c) of washing and separation comprises adding water to the reaction mass of step b) comprising an acyloxyhalogenated diene-containing (co)polymer, followed by separation of an aqueous layer and an organic layer containing the acyloxyhalogenated diene-containing (co)polymer.

In the context of the present invention, water is, but is not limited to, distilled, deionized, demineralized, osmotic, or bidistilled water.

The process of washing with water is carried out with at least one-fold, preferably two-fold, more preferably three-fold excess of water relative to the volume of the reaction mass, resulting in the separation of the reaction mass into two layers: an organic layer comprising an acyloxyhalogenated diene-containing (co)polymer, and an aqueous layer.

A permissible residual content of the halogenating agent in the organic layer after washing is from 0 to 0.5 wt.%, preferably less than 0.2% wt.%, more preferably less than 0.05 wt.%.

Preferably, the washing step is carried out at a temperature of 15 to 50°C, preferably 20 to 40°C, and more preferably 25 to 30°C, under atmospheric pressure.

The separation of the organic and aqueous layers is carried out by using any equipment known in the art, for example, a funnel, a separator, or a gravity tank.

Step d) isolation

Step d) of isolation of the acyloxyhalogenated diene-containing (co)polymer from the organic layer of step c) is carried out by two methods: precipitation or degassingof the acyloxyhalogenated diene-containing (co)polymer.

In one embodiment of the invention, the method for preparing a modified diene- containing (co)polymer is carried out through the step of precipitation of the resulting acyloxyhalogenated diene-containing (co)polymer.

In this embodiment, an alcohol-precipitant is added to the organic layer of step c) comprising an acyloxyhalogenated diene-containing (co)polymer. The weight ratio of the alcohol-precipitant to the acyloxyhalogenated diene-containing (co)polymer is from 15:1 to 1 :1, preferably 10:1 to 3:1, and more preferably from 5:1 to 4:1.

Suitable alcohol precipitants are, but are not limited to, aliphatic alcohols containing from 1 to 4 carbon atoms. Examples of such alcohols are, but are not limited to, methanol, ethanol, propanol, iso-propanol, butanol, or iso-butanol. Methanol and ethanol are preferred as the alcohol-precipitant.

In another embodiment of the invention, the method for preparing a modified diene-containing (co)polymer is carried out through the step of degassingdegassing the resulting acyloxyhalogenated diene-containing (co)polymer.

In this embodiment, water is added to the organic layer of step c), followed by degassingthe water-solvent mixture at an elevated temperature under reduced pressure to isolate the acyloxyhalogenated diene-containing (co)polymer and remove water and/or vapors thereof, the solvent and/or vapors thereof.

In the context of the present invention, water is, but is not limited to, distilled, deionized, demineralized, osmotic, or bidistilled water.

The amount of the added water relative to the organic solvent is from 1 :1 to 10:1, preferably from 1 :1 to 5 : 1 , more preferably 2:1 to 4 : 1.

According to the present invention, the temperature of water, when added to the system, is not more than 30°C, preferably not more than 25°C, more preferably not more than 20°C. The use of water with a temperature above 30°C leads to boiling and subsequent abrupt evaporation of the solvent, which in turn may change physicomechanical characteristics of the resulting acyloxyhalogenated diene-containing (co)polymer.

The process of degassing is carried out in any suitable equipment known from the art, in particular, in devices capable of providing good stirring, heat exchange and capable of maintaining reduced pressure. Examples of such devices are, but are not limited to, continuous or batch apparatuses, agitators equipped with a mixer and a jacket.

The temperature of the degassing step is from 20 to 150°C, preferably from 50 to 100°C, most preferably from 80 to 95°C.

In the degassing step, the pressure is maintained at less than 800 mbar, preferably less than 300 mbar, more preferably less than 100 mbar.

Preferably, the time of the degassing step is at least 30 min, more preferably at least 60 min, most preferably at least 120 min.

Step e) of filtration and drying

In step e) of filtration and drying, filtration, which is used to purify the acyloxyhalogenated diene-containing polymer from the residues of the solvent and alcohol-precipitant, is carried out by using any devices known in the art, for example, porous membrane filters, nutsch filters, and the like equipment.

Filtration of the acyloxyhalogenated diene-containing (co)polymer is carried out at a temperature of from 20 to 40°C, inclusive.

The process of drying the resulting acyloxyhalogenated diene-containing (co)polymer is carried out to remove water and/or vapors thereof, solvent and/or vapors thereof from said (co)polymer. The process of drying the acyloxyhalogenated diene- containing (co)polymer is carried out by physical methods usually used for separation and purification of organic compounds, in particular, such as removal of the solvent by distillation under reduced pressure, drying in a vacuum drying oven, and by using drying agents that remove moisture by adsorption, formation of hydrates or chemical reactions with water and solvents.

The drying is preferably carried out at a temperature of from 50 to 105°C and under pressure of from 1 to 20 kPa.

Step f) of dissolution

In one embodiment of the invention, in optional step f) of dissolution of the acyloxyhalogenated diene-containing (co)polymer obtained in step e), the (co)polymer is pre-ground and then is dissolved in an organic solvent with stirring.

The grinding of the acyloxyhalogenated diene-containing (co)polymer is carried out by any method known in the art, for example, by using grinders, such as knife, hummer, and rotor grinders, or millers, for example, fluid and screw millers.

Upon dissolving, the acyloxyhalogenated diene-containing (co)polymer is stirred by any method known in the art, for example, by using a device with a mixer or a static mixer at a temperature of from 10 to 50°C, preferably from 15 to 40°C, more preferably from 20 to 30°C.

Suitable solvents used in said step f) are, but are not limited to, organic solvents, preferably having a purity of 99% and more, which are ethers, for example, tetrahydrofuran; halogenated saturated aliphatic hydrocarbons, for example, carbon tetrachloride, chloroform, dibromomethane, dichloromethane, 1 ,2-dichloroethane; cycloaliphatic hydrocarbons, for example, cyclohexane; aromatic hydrocarbons, for example, toluene; halogenated aromatic hydrocarbons, for example, bromobenzene, chlorobenzene, and dichlorobenzene. Preferred organic solvents of step f) are those that are liquid under the conditions of modification of the starting diene-containing (co)polymer and that are inert under the conditions of subsequent step g) of halogenation of an acyloxyhalogenated diene-containing (co)polymer. Preferably, tetrahydrofuran, chloroform, dichloromethane, dichloroethane, cyclohexane, toluene are used as said solvent, wherein tetrahydrofuran, chloroform, dichloromethane are most preferable.

The weight ratio of the organic solvent to the acyloxyhalogenated diene- containing (co)polymer is from 5:1 to 30:1, preferably from 8:1 to 20:1, and more preferably from 10:1 to 15:1.

The time of the dissolution process is not more than 60 min, in particular, not more than 50 min, not more than 40 min, not more than 30 min, not more than 25 min, not more than 20 min, not more than 15 min, not more than 13 min, not more than 11 min, not more than 9 min, not more than 7 min, not more than 5 min.

The mass obtained in the above-mentioned step f) of dissolution is a solution of the acyloxyhalogenated diene-containing (co)polymer in the organic solvent.

Step g) of halogenation

In step g) of halogenation, a halogenating agent and optionally an aliphatic alcohol are added to the solution obtained in step f).

The halogen in the halogenating agent is chlorine, bromine, or iodine.

A preferred halogenating agent in step g) of halogenation according to the present invention is elemental bromine (Bn) as such and as a solution in an organic solvent with a bromine content of at most 70 wt.%, more preferably at most 60 wt.%, and most preferably at most 50 wt.%.

Suitable halogenating agents also are, but are not limited to, quaternary ammonium bromides, for example, phenyltriethylammonium bromide, benzyltrimethylammonium bromide, tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, tetra-n-butylammonium bromide; and quaternary phosphonium bromides, for example, tetramethylphosphonium bromide, tetraethylphosphonium bromide, tetrapropylphosphonium bromide, tetra-n- butyl phosphonium tribromide, or mixtures thereof.

Preferably, elemental bromine (B^) and quaternary ammonium bromides or quaternary phosphonium bromides are simultaneously used as the halogenating agent in step g). The use of quaternary ammonium bromide or quaternary phosphonium bromide allows avoiding significant substitution of hydrogen with bromine in tertiary and/or allylic carbon atoms, which in turn has an effect on the heat resistance of the resulting modified diene-containing (co)polymer.

The aliphatic alcohol in step g) is, but is not limited to, an alcohol containing 1 to 6 carbon atoms, such as, methanol, ethanol, propanol, iso-propanol, n-butanol, isobutanol, pentanol, iso-pentanol, or hexanol. Preferably, propanol, n-butanol, isobutanol, sec-butanol, pentanol are used as the aliphatic alcohol, wherein n-butanol, isobutanol and sec-butanol are more preferable.

The molar ratio of the acyloxyhalogenated diene-containing (co)polymer to the halogenating agent to the aliphatic alcohol in step g) is from 1 : 1.5:3 to 1 :5:3, more preferably from 1 :2:3 to 1 :4:3, most preferably from 1:2.5:3 to 1 :3:3. In one embodiment of the invention, when the halogenating agent is a combination of elemental bromine with quaternary ammonium bromide or quaternary phosphonium bromide, the molar ratio of the elemental bromine to bromine atoms in the quaternary ammonium bromide or quaternary phosphonium bromide is from 1 :1 to 1 :4, more preferably from 1 :2 to 1 :3, most preferably from 1 :1 to 1 :1.5.

The addition of the halogenating agent and the aliphatic alcohol, when used, to the solution obtained in step f) can be in any order. Preferably, the aliphatic alcohol is added first to the solution of the acyloxyhalogenated diene-containing (co)polymer, followed by addition of the halogenating agent. In addition, when the halogenating agent is a combination of elemental bromine with quaternary ammonium bromide or quaternary phosphonium bromide, the whole volume of the quaternary ammonium bromide or quaternary phosphonium bromide is added in the form of its solution in an organic solvent to the reaction mass.

The elemental bromine is preferably added in the form of its solution in an organic solvent by dosing the solution to the reaction mass at a rate of from 0.80 to 50 ml/min, preferably from 1 to 10 ml/min, more preferably from 1.5 to 5 ml/min. The dosing rate above 50 ml/min, as well as the addition of the whole volume of the solution of elemental bromine (Br2), to the solution obtained in step f) results in crosslinking the (co)polymer, local overheating the reaction mass, and an increase in its viscosity, which in turn provides a modified diene-containing (co)polymer with an undesirably low content (lower than 35 wt.%) of halogen atoms.

The halogenating agent is dissolved in an organic solvent or a mixture of organic solvents preferably having a purity of 99% and more, wherein the halogenating agent is ether, for example, tetrahydrofuran; a halogenated saturated aliphatic hydrocarbon, for example, chloroform, dibromomethane, dichloromethane, 1 ,2-dichloroethane; a cycloaliphatic hydrocarbon, for example, cyclohexane; an aromatic hydrocarbon, for example, toluene; a halogenated aromatic hydrocarbon, for example, bromobenzene, chlorobenzene, and dichlorobenzene. The halogenating agent is preferably added in the form of its solution in the solvent that was used in step f) to dissolve the acyloxyhalogenated diene-containing (co)polymer.

Step g) of halogenation is carried out in any batch or continuous process equipment known in the art. Suitable equipment is, but is not limited to, a continuous stirred tank reactor, a batch stirred tank reactor, and autoclave with a mixer, which are designed to work with highly corrosive environments.

Preferably, step g) of halogenation of the acyloxyhalogenated diene-containing (co)polymer obtained in step b) is carried out without exposure to light, for example, by carrying out the process of modification in dark glass vessels, by wrapping the reactor with foil, or in a metal reactor, in order to reduce the possibility of the non-selective photocatalytic halogenation reactions.

Step g) of halogenation is carried out at a temperature of from 0 to 50°C, preferably from 20 to 45°C, and more preferably from 30 to 40°C, under atmospheric pressure.

The rate of stirring the reaction mass after addition of the halogenating agent is from 50 to 600 rpm, preferably from 100 to 500 rpm, more preferably from 200 to 300 rpm.

The halogenation step can be carried out for any time sufficient to achieve a desired halogenation degree of the acyloxyhalogenated diene-containing (co)polymer, as described above. Preferably, the time of partial halogenation is at least 15 min, at least 20 min, at least 25 min, at least 30 min, at least 45 min, at least 60 min, at least 120 min.

The reaction mass obtained in step g) comprises the target product - a modified diene-containing (co)polymer comprising acyloxyhalogenated diene units and halogen atoms.

Step h) of neutralization and separation

Step h) of the claimed method for preparing a modified diene-containing (co)polymer according to the present invention comprises neutralization of the reaction mass of step g) comprising a modified diene-containing (co)polymer, by adding an aqueous solution of a neutralizing agent, followed by washing the neutralized reaction mass with water and separating an aqueous layer and an organic layer comprising the modified diene-containing (co)polymer.

The neutralizing agent in step h) is an aqueous basic solution known in the art, for example, such as, but is not limited to, sodium hydroxide, sodium thiosulfate, sodium bisulfite, sodium dithionite, sodium hypophosphite, sodium ascorbate, sodium carbonate. An aqueous solution of sodium hydroxide is preferable.

The molar ratio of the neutralizing agent to the halogenating agent added in step g) is usually from 1 :1 to 3 : 1 , preferably from 1 :1 to 2: 1 , more preferably 1 :1.

The neutralization step is preferably carried out at a temperature of 15 to 50°C, preferably 20 to 40°C, and more preferably 25 to 30°C, under atmospheric pressure.

The washing with water is carried out with at least one-fold, preferably two-fold, more preferably three-fold excess of water relative to the volume of the reaction mass subjected to neutralization, resulting in the separation of the reaction mass into two layers: an organic layer comprising a modified diene-containing (co)polymer, and an aqueous layer.

The separation of the organic and aqueous layers is carried out by using any equipment known in the art, for example, a funnel, a separator, or a gravity tank.

Step i) isolation

Step i) of isolation of the resulting modified diene-containing (co)polymer from the organic layer of step h) is carried out by two methods: by precipitation or degassingdegassing of the modified diene-containing (co)polymer.

In one embodiment of the invention, the method for preparing a modified diene- containing (co)polymer is carried out through the step of precipitation of the resulting modified diene-containing (co)polymer. In this embodiment, the modified diene- containing (co)polymer obtained in step g) is isolated by adding an alcoholprecipitant to the organic layer of step h) containing the modified diene-containing (co)polymer. The weight ratio of the alcoholprecipitant to the modified diene-containing (co)polymer is from 15:1 to 1 :1, preferably from 10:1 to 3:1, and more preferably from 5:1 to 4:1.

Suitable alcohol precipitants are, but are not limited to, aliphatic alcohols containing from 1 to 4 carbon atoms. Examples of such alcohols are, but are not limited to, methanol, ethanol, propanol, iso-propanol, butanol, and iso-butanol. Methanol and ethanol are preferred as the alcohol-precipitant.

In another embodiment of the invention, the method for preparing the modified diene-containing (co)polymer is carried out through the step of degassing the resulting modified diene-containing (co)polymer. According to this embodiment, in step i) of isolation, water is added to the organic layer of step h), followed by degassing the water-solvent mixture at an elevated temperature under reduced pressure to isolate the target modified diene-containing (co)polymer and to remove from it water and/or vapors thereof, the solvent and/or vapors thereof.

In the context of the present invention, water is, but is not limited to, distilled, deionized, demineralized, osmotic, or bidistilled water.

The amount of the added water relative to the organic solvent is from 1 :1 to 10:1, preferably from 1 :1 to 5:1, more preferably 2:1 to 4:1.

According to the present invention, the temperature of water, when added to the system, is not more than 30°C, preferably not more than 25°C, more preferably not more than 20°C. The temperature of the used water above 30°C results in boiling and subsequent abrupt evaporation of the solvent, which in turn may change physical- mechanical characteristics of the resulting modified diene-containing (co)polymer.

The degassing is carried out in any suitable equipment known in the art, in particular, in devices capable of providing good stirring, heat exchange and capable of maintaining reduced pressure. Examples of such devices are, but are not limited to, continuous or batch apparatuses agitators equipped with a mixer and a jacket.

The temperature of the degassing step is from 20 to 150°C, preferably from 50 to 100°C, most preferably from 80 to 95°C.

The pressure in the degassing step is maintained at values of less than 800 mbar, preferably less than 300 mbar, more preferably less than 100 mbar.

Preferably, the duration of the degassing step is at least 30 min, more preferably at least 60 min, most preferably at least 120 min.

Step j) of filtration and drying

In step j) of filtration and drying, filtration, which is used to purify the modified diene-containing polymer from the residues of the solvent and alcohol-precipitant, is carried out by using any devices known in the art, for example, porous membrane filters, nutsch-filters, and the like equipment. Filtration of the modified diene-containing (co)polymer is carried out at a temperature of from 20 to 40°C, inclusive.

The modified diene-containing (co)polymer is dried to remove water and/or vapors thereof, the solvent and/or vapors thereof. The process of drying the modified diene-containing (co)polymer is carried out by physical methods usually used for separation and purification of organic compounds, in particular, such as removal of the solvent by distillation under reduced pressure, drying in a vacuum drying oven, and by using drying agents that remove moisture by means of adsorption, formation of hydrates or chemical reactions with water and solvents.

The drying is preferably performed at a temperature of from 50 to 105°C and under pressure of from 1 to 20 kPa.

In accordance with another embodiment of the invention, the modified diene- containing (co)polymer can be prepared by a method that comprises the following steps of:

a) dissolution, the step comprising optionally pre-grinding a starting diene- containing (co)polymer, followed by dissolution in a solvent;

b) partial halogenation to a halogenation degree of at least 60%, preferably at least 90%, most preferably at least 95%, by using a halogenating agent and optionally an aliphatic alcohol;

c) washing and separation, the step comprising adding water to the reaction mass obtained in step b) and separating an aqueous and an organic layer;

d) modification, the step comprising adding components of a modifying system to the organic layer of step c) comprising a partially halogenated diene-containing (co)polymer;

e) neutralization and separation, the step comprising adding an aqueous solution of a neutralizing agent to the reaction mass obtained in step d) and separating an aqueous and an organic layer;

f) isolation, the step comprising precipitating or degassing the modified diene- containing (co)polymer from the organic layer of step e);

g) filtration and subsequent drying of the modified diene-containing (co)polymer,

wherein the method is characterized in that in step d) of modification, the modifying system is a mixture of a carboxylic acid and a halogenating agent in molar ratio of the carboxylic acid to the halogenating agent of from 1 :1 to 1000:1, preferably from 1:1 to 100:1, more preferably from 1 :1 to 10:1.

Step a) of dissolution

In step a), a starting diene-containing (co)polymer is optionally pre-ground and then dissolved in an organic solvent with stirring.

The pre-grinding of the starting diene-containing (co)polymer is carried out, if necessary, by any method known from the art, for example, by using knife, hummer, and rotor grinders, or millers, for example, fluid or screw millers.

Upon dissolving, the starting diene-containing (co)polymer is stirred by any method known from the art, for example, by using a device equipped with a mixer or a static mixer at a temperature of 10 to 50°C, preferably 15 to 40°C, more preferably 20 to 30°C.

Suitable solvents are, but are not limited to, organic solvents, preferably having a purity of 99% and more, which are ethers, for example, tetrahydrofuran, halogenated saturated aliphatic hydrocarbons, for example, carbon tetrachloride, chloroform, dibromomethane, dichloromethane, 1,2-dichloroethane; cycloaliphatic hydrocarbons, for example, cyclohexane; aromatic hydrocarbons, for example, toluene; halogenated aromatic hydrocarbons, for example, bromobenzene, chlorobenzene, and dichlorobenzene. Preferred organic solvents are those that are liquid under the conditions of modification of the starting diene-containing (co)polymer and that are inert under the conditions of step b) of partial halogenation of the starting diene- containing (co)polymer. Preferably, tetrahydrofuran, chloroform, dichloromethane, dichloroethane, cyclohexane, toluene are used as the solvent, wherein tetrahydrofuran, chloroform, dichloromethane are most preferable.

The weight ratio of the organic solvent to the starting diene-containing (co)polymer is from 5: 1 to 30:1, preferably 8: 1 to 20:1, and more preferably from 10:1 to 15:1.

The duration of the dissolution process is not more than 60 min, in particular, not more than 50 min, not more than 40 min, not more than 30 min, not more than 25 min, not more than 20 min, not more than 15 min, not more than 13 min, not more than 11 min, not more than 9 min, not more than 7 min, not more than 5 min. The mass obtained in the above-mentioned step a) of dissolution is a solution of the starting diene-containing (co)polymer in the organic solvent.

Step b) of partial halogenation

In step b) of partial halogenation, a halogenating agent and optionally an aliphatic alcohol are added to the solution of the starting diene-containing (co)polymer obtained in step a).

The halogenation degree of the partially halogenated diene-containing (co)polymer obtained in step b) is at least 60%, preferably at least 90%, most preferably at least 95%.

Step b) of partial halogenation is carried out essentially in a water-free system; namely, the permissible water content is from 0 to less than 0.5 wt.%, more preferably from 0 to less than 0.3 wt.%, even more preferably from 0 to less than 0.1 wt.%.

The halogen in the halogenating agent is chlorine, bromine, or iodine.

Preferably, the halogen is elemental bromine (Br2) as such or as a solution in an organic solvent with a bromine content of at most 70 wt.%, more preferably at most 60 wt.%, and most preferably at most 50 wt.%.

Suitable halogenating agents also are, but are not limited to, quaternary ammonium bromides, for example, phenyltriethylammonium bromide, benzyltrimethylammonium bromide, tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, tetra-n-butylammonium bromide; and quaternary phosphonium bromides, for example, tetramethylphosphonium bromide, tetraethylphosphonium bromide, tetrapropylphosphonium bromide, tetra-n- butylphosphonium tribromide, or mixtures thereof.

Preferably, elemental bromine (Bn) is used simultaneously with quaternary ammonium bromides or quaternary phosphonium bromides as the halogenating agent in step b). The use of quaternary ammonium bromide or quaternary phosphonium bromide allows avoiding significant substitution of hydrogen with bromine in tertiary and/or allylic carbon atoms, which in turn has an effect on the heat resistance of the resulting modified diene-containing (co)polymer.

The aliphatic alcohol is, but is not limited to, an alcohol containing 1 to 6 carbon atoms, such as, methanol, ethanol, propanol, iso-propanol, butanol, iso-butanol, pentanol, iso-pentanol, or hexanol. Preferably, propanol, n-butanol, iso-butanol, pentanol are used as the aliphatic alcohol, wherein n-butanol, iso-butanol and pentanol are more preferable.

The molar ratio of the starting diene-containing (co)polymer to the halogenating agent to the aliphatic alcohol is from 1 : 1.5:3 to 1 :5:3, more preferably from 1 :2:3 to 1 :4:3, most preferably from 1 :2.5:3 to 1 :3:3. In addition, when the halogenating agent is a combination of elemental bromine with quaternary ammonium bromide or quaternary phosphonium bromide, the molar ratio of the elemental bromine to bromine atoms in the quaternary ammonium bromide or quaternary phosphonium bromide is from 1 :1 to 1 :4, more preferably from 1 :2 to 1 :3, most preferably from 1 : 1 to 1 : 1.5.

The addition of the halogenating agent and the aliphatic alcohol, when used, to the solution of the starting diene-containing (co)polymer obtained of step a) can be performed in any order. Preferably, aliphatic alcohol is added first to the solution of the starting diene-containing (co)polymer, followed by addition of the halogenating agent. In addition, when the halogenating agent is a combination of quaternary ammonium bromide or quaternary phosphonium bromide with elemental bromine, the whole volume of the quaternary ammonium bromide or quaternary phosphonium bromide is added in the form of its solution in an organic solvent to the reaction mass.

In step b) of partial halogenation, the elemental bromine is preferably added in the form of its solution in an aliphatic solvent by dosing the solution to the reaction mass at a rate of from 0.80 to 50 ml/min, preferably from 1 to 10 ml/min, more preferably from 1.5 to 5 ml/min. The dosing rate above 50 ml/min, as well as the addition of the whole volume of the elemental bromine (Bn) solution to the solution obtained in step a) results in crosslinking the (co)polymer, local overheating the reaction mass, an increase in its viscosity, which in turn provides a modified diene-containing (co)polymer with an undesirably low content (lower than 35 wt.%) of halogen atoms

The organic solvent used to dissolve the halogenating agent is a solvent or a mixture of solvents preferably having a purity of 99% and more, selected from ether, for example, tetrahydrofuran; a halogenated saturated aliphatic hydrocarbon, for example, chloroform, dibromomethane, dichloromethane, 1,2-dichloroethane; a cycloaliphatic hydrocarbon, for example, cyclohexane; an aromatic hydrocarbon, for example, toluene; a halogenated aromatic hydrocarbon, for example, bromobenzene, chlorobenzene, and dichlorobenzene. The halogenating agent is preferably added in the form of its solution in the solvent that was used in step a) to dissolve the starting diene-containing (co)polymer.

Step b) of partial halogenation is carried out in any batch or continuous process equipment known from the art. Suitable equipment is, but is not limited to, a continuous stirred tank reactor, a batch stirred tank reactor, and autoclave with a mixer, which are designed to work with highly corrosive environments.

The partial halogenation step of the solution of the starting diene-containing (co)polymer of step a) is preferably carried out without exposure to light, for example, by carrying out the halogenation process in dark glass vessels, by wrapping the reactor with foil, or in a metal reactor, to reduce the possibility of the non-selective photocatalytic halogenation reactions.

Step b) of partial halogenation is carried out at a temperature of 0 to 50°C, preferably 20 to 45°C, and more preferably 30 to 40°C, under atmospheric pressure.

The rate of stirring of the reaction mass after addition of the halogenating agent is from 50 to 600 rpm, preferably from 100 to 500 rpm, more preferably from 200 to 300 rpm.

The partial halogenation step can be carried out for any time sufficient to achieve a desired halogenation degree of the starting diene-containing (co)polymer, as described above. Preferably, the time of the partial halogenation is at least 15 min, at least 20 min, at least 25 min, at least 30 min, at least 45 min, at least 60 min, at least 120 min.

Step c) washing and separation

In step c) of washing and separation, water is added to the reaction mass of step b) comprising a partially halogenated diene-containing (co)polymer, followed by separation of an aqueous layer and an organic layer containing the partially halogenated diene-containing (co)polymer.

In the context of the present invention, water is, but is not limited to, distilled, deionized, demineralized, osmotic, or bidistilled water.

The washing with water is carried out with at least one-fold, preferably two-fold, more preferably three-fold excess of water relative to the volume of the reaction mass, resulting in separation of the reaction mass into two layers: an organic layer comprising a partially epoxidized diene-containing (co)polymer, and an aqueous layer. A permissible residual content of the halogenating agent in the organic layer after washing is from 0 to 0.5 wt.%, preferably less than 0.2% wt.%, more preferably less than 0.05 wt.%.

Preferably, the washing step is carried out at a temperature of 15 to 50°C, preferably 20 to 40°C, and more preferably 25 to 30°C, under atmospheric pressure.

The separation of the organic and aqueous layers is carried out by using any equipment known from the art, for example, by using a funnel, a separator, or a gravity tank.

Step d) of modification

In step d), the modification is carried out by adding components of a modifying system to the organic layer of step c) comprising a partially halogenated diene- containing (co)polymer.

According to the present invention, the modifying system is a carboxylic acid and a halogenating agent in a molar ratio of the carboxylic acid to the halogenating agent of from 1 :1 to 1000:1, preferably from 1 :1 to 100:1, more preferably from 1 :1 to 10:1.

The halogen in the halogenating agent is chlorine, bromine, or iodine. However, bromine is preferred as a halogen in the halogenating agent.

The halogenating agent can be, but is not limited to, bromoimide, for example, N-bromosuccinimide, N-bromophthalimide; or bromoamide, for example, N- bromoacetamide, or bromourea, for example, tetrabromoglycoluril, as such or as solutions in solvents with a concentration of from 1% to 50%.

The carboxylic acids is, but is not limited to, a Ci-Cs alkyl carboxylic acid, for example, acetic acid, propionic acid, 2-ethylhexanoic acid; a halogen-containing Ci-Cs acid, for example, bromoacetic acid, 2-bromopropionic acid; a Ce-Cs alkylcarboxylic acid, for example, benzoic acid, 4-methylbenzoic acid; a halogen-substituted C6- Csarylcarboxylic acid, for example 4-bromobenzoic acid, or a combination thereof. Acetic acid, propionic acid, bromoacetic acid, benzoic acid, and 4-bromobenzoic acid are preferred as the carboxylic acid. The presence of additional halogen atoms in the acid allows to achieve further improvement of flame-retardant properties of the modified diene-containing (co)polymer.

The molar ratio of the halogenating agent to double bonds in the partially halogenated diene-containing (co)polymer is from 0.001 :1 to 0.1 :1, more preferably from 0.01 :1 to 0.05:1, most preferably from 0.01 :1 to 0.02:1.

The addition of components of the modifying mixture to the organic layer of step c) comprising the partially halogenated diene-containing (co)polymer can be performed in any order. Carboxylic acid is preferably added first with subsequent addition of the halogenating agent.

The halogenating agent is dissolved in an organic solvent preferably having a purity of 99% and more, wherein the organic solvent is ether, for example, tetrahydrofuran; a halogenated saturated aliphatic hydrocarbon, for example, chloroform, dibromomethane, dichloromethane, 1,2-dichloroethane; a cycloaliphatic hydrocarbon, for example, cyclohexane; an aromatic hydrocarbon, for example, toluene; a halogenated aromatic hydrocarbon, for example, bromobenzene, chlorobenzene, and dichlorobenzene. The halogenating agent is preferably added in the form of its solution in the solvent that was used in step a) to dissolve the starting diene-containing (co)polymer.

The modification step is carried out in any batch or continuous process equipment known from the art. A suitable equipment is, but is not limited to, a continuous stirred tank reactor, a batch stirred tank reactor, and autoclave with a mixer, which are designed to work with highly corrosive environments.

Step d) of modification of the partially halogenated diene-containing (co)polymer is preferably carried out without exposure to light, for example, by carrying out the modification process in dark glass vessels, by wrapping the reactor with foil, or in a metal reactor, to reduce the possibility of the non-selective photocatalytic halogenation reactions.

Step d) of modification is carried out at a temperature of 0 to 100°C, preferably 20 to 80°C, and more preferably 40 to 60°C, under atmospheric pressure.

The rate of stirring of the reaction mass after addition of the modifying system is from 50 to 600 rpm, preferably from 100 to 500 rpm, more preferably from 200 to 300 rpm.

The modification can be carried out for any time sufficient to achieve a desired modification degree of the starting diene-containing (co)polymer, as described above. Preferably, the duration of step d) of modification is at least 15 min, at least 20 min, at least 25 min, at least 30 min, at least 45 min, at least 60 min, at least 120 min.

The mass obtained in step d) of modification comprises the target modified diene-containing (co)polymer comprising acyloxyhalogenated diene units and halogen atoms, and having an acyloxyhalogenation degree of at least 0.01%, preferably at least 0.1%, most preferably 1%.

Step e) of neutralization and separation

Step e) according to this embodiment of the invention comprises neutralization of the reaction mass of step d) comprising a modified diene-containing (co)polymer, by adding a solution of a neutralizing agent, followed by washing the neutralized reaction mass with water and separating an aqueous layer and an organic layer comprising the modified diene-containing (co)polymer.

The neutralizing agent is any aqueous basic solution known from the art, such as, but is not limited to, a solution of sodium hydroxide, sodium thiosulfate, sodium bisulfite, sodium dithionite, sodium hypophosphite, sodium ascorbate, sodium carbonate. An aqueous solution of sodium hydroxide is preferable.

The molar ratio of the neutralizing agent added in step e) to the halogenating agent added in step b) is usually from 1 :1 to 3: 1, preferably from 1 : 1 to 2:1, more preferably 1 :1.

The neutralization is step e) is preferably carried out at a temperature of from 15 to 50°C, preferably from 20 to 40°C, and more preferably from 25 to 30°C, under atmospheric pressure.

The washing with water is carried out with at least one-fold, preferably two-fold, more preferably three-fold excess of water relative to the volume of the reaction mass subjected to neutralization, resulting in the separation of the reaction mass into two layers: an organic layer comprising an aqueous layer and a modified diene-containing (co)polymer.

The separation of the organic and aqueous layers is carried out by using any equipment known in the art, for example, by using a funnel, a separator, or a gravity tank.

Step f) isolation

Step f) of isolation of the resulting modified diene-containing (co)polymer from the organic layer of step e) is carried out by two methods: by precipitation or degassing of the modified diene-containing (co)polymer.

In one embodiment of the invention, the method for preparing a modified diene- containing (co)polymer is carried out through the step of precipitation of the resulting modified diene-containing (co)polymer. In this embodiment, the modified diene- containing (co)polymer obtained in step d) is isolated by adding an alcohol-precipitant to the organic layer of step e) containing the modified diene-containing (co)polymer. The weight ratio of the alcohol-precipitant to the modified diene-containing (co)polymer is from 15:1 to 1:1, preferably from 10:1 to 3:1, and more preferably from 5:1 to 4:1.

Suitable alcohol precipitants are, but are not limited to, aliphatic alcohols containing from 1 to 4 carbon atoms. Examples of such alcohols are, but are not limited to, methanol, ethanol, propanol, iso-propanol, butanol, and iso-butanol. Methanol and ethanol are preferred as the alcohol-precipitant.

In another embodiment, the method for preparing a modified diene-containing (co)polymer is carried out through the step of degassing the resulting modified diene- containing (co)polymer, wherein in step f) of isolation, water is added to the organic layer of step e), and then the water-solvent mixture is distilled at an elevated temperature and under reduced pressure to isolate the target modified diene-containing (co)polymer and to remove water and/or vapors thereof, the solvent and/or vapors thereof.

In the context of the present invention, water is, but is not limited to, distilled, deionized, demineralized, osmotic, or bidistilled water.

The amount of the added water relative to the organic solvent is from 1:1 to 10:1, preferably from 1:1 to 5:1, more preferably from 2:1 to 4:1.

According to the present invention, the temperature of water, when added in step f), is not more than 30°C, preferably not more than 25°C, more preferably not more than 20°C. The use of water with a temperature above 30°C leads to boiling and subsequent abrupt evaporation of the solvent, which in turn may change physicomechanical characteristics of the resulting modified diene-containing (co)polymers.

The degassing is carried out in any suitable equipment known in the art, in particular, in devices capable of providing good stirring, heat exchange and capable of maintaining reduced pressure. Examples of such devices are, but are not limited to, continuous or batch apparatuses agitators equipped with a mixer and a jacket.

The temperature of the degassing step is from 20 to 150°C, preferably from 50 to 100°C, and most preferably from 80 to 95°C.

The pressure in the degassing step is maintained at less than 800 mbar, preferably less than 300 mbar, more preferably less than 100 mbar.

Preferably, the duration of the degassing process in step f) is at least 30 min, more preferably at least 60 min, most preferably at least 120 min.

Step g) of filtration and drying

In step g) of filtration and drying, filtration, which is used to purify the modified diene-containing polymer from the residues of the solvent and alcohol precipitant, is carried out by using any devices known in the art, for example, porous membrane filters, nutsch-filters, and the like equipment.

Filtration of the modified diene-containing (co)polymer is carried out at a temperature of from 20 to 40°C, inclusive.

The modified diene-containing (co)polymer is dried to remove water and/or vapors thereof, the solvent and/or vapors thereof. The process of drying the modified diene-containing (co)polymer is carried out by physical methods usually used for separation and purification of organic compounds, for example, by removing the solvent by distillation under reduced pressure, drying in a vacuum drying oven, and by using drying agents that remove moisture by means of adsorption, formation of hydrates or chemical reactions with water and solvents.

The drying is preferably performed at a temperature of from 50 to 105°C and under pressure of from 1 to 20 kPa.

In addition, according to yet another embodiment of the present invention, a modified diene-containing (co)polymer comprising acyloxyhalogenated diene units and halogen atoms is prepared by reacting a hydroxyhalogenated diene-containing (co)polymer with an acylating system.

Thus, yet another method proposed according to the present invention for preparing a modified diene-containing (co)polymer comprising acyloxyhalogenated diene units comprises the following steps of:

a) preparing a hydroxyhalogenated diene-containing (co)polymer;

b) dissolution of the hydroxyhalogenated diene-containing (co)polymer obtained in step a) in a solvent;

c) acylation, the step comprising adding components of an acylating system to the solution obtained in step b);

d) washing and separation, the step comprising adding water to the reaction mass obtained in step c) and separating an aqueous and an organic layer;

e) isolation, the step comprising precipitating or degassing a modified diene- containing (co)polymer from the organic layer obtained in step d);

e) filtration and subsequent drying of the isolated modified diene-containing (co)polymer.

Step a) of preparing a hydroxyhalogenated diene-containing (co)polymer

A hydroxyhalogenated diene-containing (co)polymer comprising hydroxyhalogenated diene units and halogen atoms can be prepared by any method known in the art, which allows the introduction of hydroxyl groups and halogen atoms into the structure of a diene-containing (co)polymer, for example, by the method disclosed in application WO2016123263.

In particular, a starting diene-containing (co)polymer for preparing a hydroxyhalogenated diene-containing (co) polymer is a polymer or copolymer of conjugated dienes.

Suitable conjugated dienes are C4-Ci2Conjugated dines, for example, 1,3- butadiene, 2-methyl- 1,3 -butadiene (isoprene), 2-ethyl- 1,3 -butadiene, 2,3-di(Ci-Cs alkyl)- 1,3 -butadienes, such as 2, 3-dimethyl-l, 3-butadiene, 2, 3-diethyl-l, 3-butadiene, 2- methyl-3 -ethyl- 1,3 -butadiene, 2-methyl-3 -isopropyl- 1,3 -butadiene, phenyl- 1,3- butadiene, 1,3-pentadiene, 2,4-hexadiene, 2-methyl-pentadiene, 4-methyl-pentadiene, or mixtures thereof. The use of 1,3 -butadiene or isoprene are preferable.

Suitable comonomers in the starting diene-containing (co)polymer are vinyl aromatic compounds, such as a-methylstyrene, ortho-, metha- and para-methylstyrene, 3-vinyltoluene, ethylvinylbenzene, 4-cyclohexylstyrene, para-/er/-butylstyrene, methoxystyrenes, vinyl mesitylene, divinylbenzebe, 1 -vinylnaphthalene, 2,4,6- trimethylstyrene or mixtures thereof. Styrene or a-methyl styrene are preferable.

Suitable polymers and copolymers of conjugated dienes comprise at least 30 wt.%, preferably at least 50 wt.%, more preferably at least 70 wt.% of polymerized conjugated diene units. Preferable (co)polymers used as the diene-containing (co)polymer are, such as butadiene polymer, styrene-butadiene copolymer, and styrene-butadiene-isoprene copolymer, wherein the use of styrene-butadiene copolymer, which is di- or tri-block copolymer of butadiene and styrene, is most preferable.

Examples of commercially available diene-containing (co)polymers are, but are not limited to, butadiene polymers with trade names BR-1243 Nd, grade B (LP), BR- 1243 Nd, grade B, and BR-1243 ND HV, styrene-butadiene block copolymers with trade names DST R 30-00, SBS L 30-01A, SBS R 30-00A, DST L 30-01, and DST L 30-01 (SR), and styrene-butadiene copolymer prepared by the solution polymerization method, under trade names DSSK-2560-M27 (grade AA), DSSK-2560-M27 BB (grade A), DSSK-4040-M27 (grade A) produced by PJC "SIBUR-Holding".

Suitable starting diene-containing (co)polymers have a weight-average molecular weight of at least 700 g/mol, preferably from 1000 to 400000 g/mol, more preferably from 2000 to 300000 g/mol, more preferably from 5000 to 200000 g/mol, more preferably from 20000 to 120000 g/mol, and most preferably from 20000 to 50000 g/mol, with a polydispersity index of from 0.8 to 3, more preferably from 1 to 1.8, and most preferably from 1.1 to 1.5, with the number of 1,2-units of equal to at least from 50 to 99 wt.%, more preferably from 60 to 80 wt.% per polybutadiene part of the (co)polymer.

Step b) of dissolution

In step b) of dissolution, the hydroxyhalogenated diene-containing (co)polymer obtained in step a) is optionally pre-ground, followed by dissolution in an organic solvent with stirring.

The grinding of the hydroxyhalogenated diene-containing (co)polymer is carried out, if necessary, by any method known in the art, for example, by using grinders, such as knife, hummer, and rotor grinders, fluid and screw millers, and the like equipment.

Upon dissolving, the starting diene-containing (co)polymer is stirred by any method known in the art, for example, by using a device equipped with a mixer or a static mixer at a temperature of from 10 to 50°C, preferably from 15 to 40°C, more preferably from 20 to 30°C.

Suitable solvents are, but are not limited to, organic solvents, preferably having a purity of 99% and more, which are ethers, for example, tetrahydrofuran, halogenated saturated aliphatic hydrocarbons, for example, carbon tetrachloride, chloroform, dibromomethane, dichloromethane, 1,2-dichloroethane; cycloaliphatic hydrocarbons, for example, cyclohexane; aromatic hydrocarbons, for example, toluene; halogenated aromatic hydrocarbons, for example, bromobenzene, chlorobenzene, and dichlorobenzene. Preferred organic solvents are those that are liquid under the conditions of acylation of the hydroxyhalogenated diene-containing (co)polymer and that are inert under the conditions of step c) of acylation of the hydroxyhalogenated diene-containing (co)polymer. Tetrahydrofuran, chloroform, dichloromethane, dichloroethane, cyclohexane, and toluene are preferable, wherein tetrahydrofuran, chloroform, and dichloromethane are most preferable.

The weight ratio of the organic solvent to the starting diene-containing (co)polymer is from 5:1 to 30:1, preferably 8:1 to20:l, and more preferably from 10:1 to 15:1.

The time of step b) of dissolution is not more than 60 min, in particular, not more than 50 min, not more than 40 min, not more than 30 min, not more than 25 min, not more than 20 min, not more than 15 min, not more than 13 min, not more than 11 min, not more than 9 min, not more than 7 min, not more than 5 min.

The mass obtained in the above-described step b) of dissolution is a solution of the hydroxyhalogenated diene-containing (co)polymer in the organic solvent.

Step c) of acylation

In step c) of acylation, components of an acylating system are added to the solution of the hydroxyhalogenated diene-containing (co)polymer, obtained in step b).

In step c), the reaction of acylation of hydroxyl groups in the molecule of the hydroxyhalogenated diene-containing (co)polymer proceeds via substitution of hydrogen atoms in the hydroxyl groups with acyl groups to form acyloxy groups.

According to the present invention, the acylating system is an activated carboxylic acid derivative and a base.

The activated carboxylic acid derivative is a carboxylic acid anhydride, acyl halide, or carboxylic acid imidazolide. Carboxylic acid anhydrides and acyl halides are preferable. The most preferable are anhydrides and chloranhydrides of carboxylic acids. These derivatives can be dissolved in any suitable solvent; however, it is preferable to use the solvent that was used in step b) to dissolve the hydroxyhalogenated diene- containing (co)polymer. The concentration of the solution can be from 1% to 99%, preferably from 2% to 80%.

The base is an organic or inorganic compound that has basic properties and is able to neutralize the acid released by the reaction. The inorganic base is, for example, an alkali metal hydroxide, an alkali metal carbonate, or an alkali metal phosphate. It is preferable to use an organic base comprising a free amino group to provide an effective diffusion to the polymer molecules. The most preferable are tertiary amines, for example, triethylamine or tributylamine, and nitrogenous heterocycles, for example, pyridine or 4-dimethylaminopyridine. The organic base can be dissolved in a suitable solvent; however, it is preferable to use the solvent that was used in step b) to dissolve the hydroxyhalogenated diene-containing (co)polymer. The concentration of the solution can be from 1% to 99%, preferably from 2% to 80%.

The molar ratio of the activated carboxylic acid derivative to the base is from 1 : 1 to 1 :10, preferably from 1 :1 to 1 :5, more preferably from 1:1.1 to 1 :3. In some cases, for example, in the case of using acid imidazolides, a base is not used.

The components of the acylating system are added to the solution of the hydroxyhalogenated diene-containing (co)polymer obtained in step b) in any order. Preferably, carboxylic acid is added first to the solution of the hydroxyhalogenated diene-containing (co)polymer, followed by addition of the base, or the carboxylic acid and base are added simultaneously, or the base is added first with subsequent addition of the acid.

The step of acylation is carried out in any batch or continuous process equipment known in the art. A suitable equipment is, but is not limited to, a continuous stirred tank reactor, a batch stirred tank reactor, and autoclave with a mixer, which are designed to work with corrosive environments.

The acylation step of the hydroxyhalogenated diene-containing (co)polymer is preferably carried out without exposure to light, for example, by carrying out the acylation process in dark glass vessels, by wrapping the reactor with foil, or in a metal reactor, to reduce the possibility of the non-selective photocatalytic halogenation reactions.

The acylation step is carried out at a temperature of from 0 to 100°C, preferably from 0 to 80°C, and more preferably from 20 to 60°C, under atmospheric pressure. The rate of stirring the reaction mass after addition of the acylating system is from 50 to 600 rpm, preferably from 100 to 500 rpm, more preferably from 200 to 300 rpm.

The duration of step c) of acylation can be any sufficient to achieve a desired acylation degree of the hydroxyhalogenated diene-containing (co)polymer, as disclosed above. Preferably, the duration of step c) is at least 15 min, at least 20 min, at least 25 min, at least 30 min, at least 45 min, at least 60 min, at least 120 min.

The mass obtained after step c) of acylation comprises the target modified diene- containing (co)polymer having an acyloxyhalogenation degree of at least 0.01%, preferably at least 0.1%, most preferably 1%.

Step d) washing and separation

Step d) washing and separation is carried out by adding water to the reaction mass of step c) comprising a modified diene-containing (co)polymer followed by separation of an aqueous layer and an organic layer comprising the modified diene- containing (co)polymer.

In the context of the present invention, water is, but is not limited to, distilled, deionized, demineralized, osmotic, or bidistilled water.

The washing with water is carried out with at least one-fold, preferably two-fold, more preferably three-fold excess of water relative to the volume of the reaction mass, resulting in separation of the reaction mass into two layers: an aqueous layer and an organic layer comprising a modified diene-containing (co)polymer.

The washing process is preferably carried out at a temperature of from 15 to 50°C, preferably from 20 to 40°C, and more preferably from 25 to 30°C, under atmospheric pressure.

The separation of the organic and aqueous layers is carried out by using any equipment known in the art, for example, by using a funnel, a separator, or a gravity tank.

Step e) isolation

Step e) of isolation of the obtained modified diene-containing (co)polymer from the organic layer of step d) is carried out by two methods: precipitation or degassing of the modified diene-containing (co)polymer.

In one embodiment of the invention, an alcohol-precipitant is added to the organic layer of step d) comprising the modified diene-containing (co)polymer. The weight ratio of the alcohol precipitant to the modified diene-containing (co)polymer is from 15:1 to 1 :1, preferably from 10:1 to 3:1, and more preferably from 5:1 to 4:1.

Suitable alcohol precipitants are, but are not limited to, aliphatic alcohols containing from 1 to 4 carbon atoms. Examples of such alcohols are, but are not limited to, methanol, ethanol, propanol, iso-propanol, butanol, and iso-butanol. Methanol and ethanol are preferred as the alcohol-precipitant.

In another embodiment of the invention, the method is carried out through the step of degassing the resulting modified diene-containing (co)polymer. In this case, water is added to the organic layer of step d), followed by degassing the water-solvent mixture at an elevated temperature under reduced pressure to isolate the modified diene- containing (co)polymer and to remove water and/or vapors thereof, the solvent and/or vapors thereof.

In the context of the present invention, water is, but is not limited to, distilled, deionized, demineralized, osmotic, or bidistilled water.

The amount of the added water relative to the organic solvent is from 1 :1 to 10:1, preferably from 1 :1 to 5:1, more preferably 2:1 to 4:1.

According to the present invention, the temperature of water, when added to the system, is not more than 30°C, preferably not more than 25°C, more preferably not more than 20°C. The use of water with a temperature above 30°C leads to boiling and subsequent abrupt evaporation of the solvent, which in turn may change physicomechanical characteristics of the resulting modified diene-containing (co)polymer.

The degassing is carried out in any suitable equipment known from the art, in particular, in devices capable of providing good stirring, heat exchange and capable of maintaining reduced pressure. Examples of such devices are, but are not limited to, continuous or batch apparatuses agitators equipped with a mixer and a jacket.

The temperature of the degassing step is from 20 to 150°C, preferably from 50 to 100°C, and most preferably from 80 to 95°C.

The pressure in the degassing step is maintained at less than 800 mbar, preferably less than 300 mbar, more preferably less than 100 mbar.

Preferably, the duration of the degassing is at least 30 min, more preferably at least 60 min, most preferably at least 120 min.

Step f) of filtration and drying

In step f) of filtration and drying, filtration, which is used to purify the modified diene-containing polymer from the residues of the solvent and alcohol precipitant, is carried out by using any devices known in the art, for example, porous membrane filters, nutsch-filters, and the like equipment.

Filtration of the modified diene-containing (co)polymer is carried out at a temperature of from 20 to 40°C, inclusive.

The modified diene-containing (co)polymer is dried to remove from water and/or vapors thereof, the solvent and/or vapors thereof. The process of drying the modified diene-containing (co)polymer is carried out by physical methods usually used for separation and purification of organic compounds, for example, by removing the solvent by distillation under reduced pressure, drying in a vacuum drying oven, and by using drying agents that remove moisture by means of adsorption, formation of hydrates or chemical reactions with water and solvents.

The drying is preferably performed at a temperature of from 50 to 105°C and under pressure of from 1 to 20 kPa.

In accordance with one embodiment, the present invention is explained in more detail in Fig. 1, which is a flowchart of the preparation of a modified diene-containing (co)polymer, wherein 101 is a dissolution unit of a starting diene-containing (co)polymer, 102 is a modification unit of the starting diene-containing (co)polymer, 103 is a washing and separation unit, 104 is an isolation unit, 105 is a filtration unit, 106 is a drying unit, 107 is a dissolution unit of an acyloxyhalogenated diene-containing (co)polymer, 108 is a partial halogenation unit of the acyloxyhalogenated diene- containing (co)polymer, 109 is a neutralization and separation unit, 110 is an isolation unit, 111 is a filtration unit, and 112 is a drying unit.

According to the presented method, optionally pre-ground starting diene- containing (co)polymer (1) is delivered to dissolution unit 101, wherein it is mixed with organic solvent (2) to obtain solution (3) of the starting diene-containing (co)polymer. Further, said solution (3) of the (co)polymer is delivered to modification unit 102 to which modifying system (4) is supplied as well. After that, acyloxyhalogenated diene- containing (co)polymer (5) obtained in unit 102 is delivered to washing and separation unit 103 to which water (6) is supplied, and then organic layer (8) comprising acyloxyhalogenated diene-containing (co)polymer is separated from aqueous layer (7). Further, organic layer (8) comprising acyloxyhalogenated diene-containing (co)polymer is delivered to isolation unit 104. After that, isolated acyloxyhalogenated diene- containing (co)polymer (9) is sequentially (9, 10) delivered to filtration unit 105 and drying unit 106 to obtain acyloxyhalogenated diene-containing (co)polymer (11).

Then, pre-ground (is not shown) acyloxyhalogenated diene-containing (co)polymer (11) is delivered to dissolution unit 107 where it is mixed with organic solvent (12) to obtain solution (13) of the acyloxyhalogenated diene-containing (co)polymer. Further, dissolved (co)polymer (13) is delivered to partial halogenation unit 108 that is also charged with halogenating agent (14) and optionally with aliphatic alcohol (15). After that, modified diene-containing (co)polymer (16) obtained in unit 108 is directed to neutralization unit 109 that is charged with neutralizing agent (17) with subsequent addition of water (17) for washing the neutralized reaction mass, after which organic layer (20) comprising modified diene-containing (co)polymer is separated from aqueous layer (19). Then organic layer (20) comprising modified diene- containing (co)polymer is delivered to isolation unit 110 to isolate the modified diene- containing (co)polymer. Further, isolated modified diene-containing (co)polymer (21) is sequentially (21, 22) delivered to filtration unit 111 and drying unit 112 to obtain the final product, which is modified diene-containing (co)polymer (23). The method for preparing a modified diene-containing (co)polymer can comprise a regeneration unit of the organic solvent with subsequent recycling thereof to dissolution unit 101 of the starting diene-containing (co)polymer (not shown in Fig. 1).

In accordance with another embodiment, the present invention is explained in more detail in Fig. 2, which is a flowchart of the preparation of a modified diene- containing (co)polymer, wherein 201 is a dissolution unit of an starting diene- containing (co)polymer, 202 is a partial halogenation unit of a dissolved starting diene- containing(co) polymer, 203 is a washing and separation unit, 204 is a modification unit of the partially halogenated diene-containing (co)polymer, 205 is a neutralization and separation unit, 206 is an isolation unit, 207 is a filtration unit, and 208 is a drying unit.

According to the presented method, optionally pre-ground starting diene- containing (co)polymer (1) is delivered to dissolution unit 201 where it is mixed with organic solvent (2) to obtain solution (3) of the starting diene-containing (co)polymer. Further, said solution (3) of the (co)polymer is delivered to partial halogenation unit 202 to which halogenating agent (4) and optionally aliphatic alcohol (5) are supplied as well. After that, partially halogenated diene-containing (co)polymer (6) obtained in unit 202 is delivered to washing and separation unit 203 that is charged with water (7), after which organic layer (9) comprising the partially halogenated diene-containing (co)polymer is separated from aqueous layer (8). Further, organic layer (9) comprising the partially halogenated diene-containing (co)polymer is delivered to modification unit 204 that is also charged with modifying system (10). After that, modified diene- containing (co)polymer (11) obtained in unit 204 is directed to neutralization and separation unit 205 that is charged with neutralizing agent (12) with subsequent addition of water (13) for washing the neutralized reaction mass, after which organic layer (15) comprising the modified diene-containing (co)polymer is separated from aqueous layer (14). Then, organic layer (15) comprising the modified diene-containing (co)polymer is delivered to isolation unit 206. Further, isolated modified diene-containing (co)polymer (16) is sequentially (16, 17) delivered to filtration unit 207 and drying unit 208 to obtain the final product, which is modified diene-containing (co)polymer (18). The method for preparing a modified diene-containing (co)polymer can also comprise a regeneration unit of the organic solvent with subsequent recycling thereof to dissolution unit 201 of the starting diene-containing (co)polymer (not shown in Fig. 2).

In accordance with yet another embodiment, the present invention is explained in more detail in Fig. 3, which is a flowchart of the preparation of a modified diene- containing (co) polymer, wherein 301 is a preparation unit of a hydroxyhalogenated diene-containing (co)polymer, 302 is a dissolution unit of the hydroxyhalogenated diene-containing (co)polymer, 303 is an acylation unit of the hydroxyhalogenated diene-containing (co)polymer, 304 is a washing and separation unit, 305 is an isolation unit, 306 is a filtration unit, and 307 is a drying unit.

According to the presented method, initial diene-containing (co)polymer (1), which is optionally pre-ground, is delivered to preparation unit 301 of a hydroxyhalogenated diene-containing (co)polymer. Further, prepared hydroxyhalogenated diene-containing (co)polymer (2) is delivered to dissolution unit 302 that is also charged with solvent (3) to obtain solution (4) of the hydroxyhalogenated diene-containing (co)polymer. Said solution (4) of the (co)polymer is then delivered to acylation unit 303 that is also charged with acylating system (5). After that, modified diene-containing (co)polymer (6) obtained in unit 303 is directed to washing and separation unit 304 to which water (7) is supplied, and then organic layer (9) comprising the modified diene-containing (co)polymer is separated from aqueous layer (8). Further, organic layer (9) comprising the modified diene-containing (co)polymer is delivered to isolation unit 305. Then, isolated modified diene-containing (co)polymer (10) is sequentially (10, 11) delivered to filtration unit 306 and drying unit 307 to obtain the target product, which is modified diene-containing (co)polymer (12). The method for preparing a modified diene-containing (co)polymer can also comprise a regeneration unit of the organic solvent with subsequent recycling thereof to dissolution unit 301 of the starting diene-containing (co)polymer (not shown in Fig. 3).

The flowcharts in Figs 1, Fig.2, and Fig.3 are examples of the present invention and are not intended to limit hereof.

The modified diene-containing (co)polymers prepared according to the present invention can be used as flame retardants in various polymers and polymer compositions, for example, which are based on expandable polystyrene, to provide them with flame retardant properties. In addition, flame retardants should be compatible with polymer or a polymer composition.

According to the present invention, the modified diene-containing (co)polymer is added to expandable polystyrene in the step of preparing thereof by a method comprising preparing polystyrene by polymerizing styrene in the presence of a polymerization initiator, a polymerization stabilizer, and other components, followed by expanding the prepared polystyrene (see, for example, US5086078).

In this case, the content of the modified diene-containing (co)polymer, which is used as a flame retardant, should not be lower than 0.5 weight part, preferably not lower than 0.7 weight part, more preferably not lower than 1 weight part, otherwise, the efficiency of improving the flame retardant characteristics of the prepared expanded polystyrene is reduced.

In addition, expandable polystyrene-based compositions according to the invention can also include usual additives ensuring the achievement of a desired complex of technological, physical-mechanical, and operational characteristics, for example, such as antistatics, stabilizers, dyes, lubricants, fillers, adhesion reducing agents.

According to the present invention, expandable polystyrene-based compositions can be used for the production of a large variety of products, such as constructive heat- and sound-insulators, in particular, heat- and sound insulation boards, permanent forms, car components, floatable articles, as well as a raw material for polystyrene foam blocks required in the construction of roads and bridges and packing domestic appliances.

The modified diene-containing (co)polymer prepared according to the present invention is used as a flame retardant in expandable polystyrene since this (co)polymer is characterized a high heat resistance, in particular, a 5% weight loss temperature of at least 180°C measured by thermogravimetric analysis, does not affect the polymerization process and the process of the formation of granules of polystyrene, which is confirmed by the particle-size distribution of the prepared polystyrene. In addition, the flame retardant prepared according to the present invention confers flame retardant properties to expandable polystyrene and does not affect its characteristics and properties.

In addition, the flame retardant prepared according to the present invention confer flame retardant properties to expandable polystyrene, which allows said expandable polystyrene that comprises the flame retardant according to the claimed invention to be classified as moderately flammable material of the inflammability class B2 (according to Item 7 of Article 13 of "Technical regulations of fire safety requirements" (Federal Act of 22.07.2008, No. 123, in the edition of 29.07.2017).

The present invention is described in detail in the examples below. These examples are given only as illustration of the present invention and are not intended to limit the present invention.

Embodiments of the invention

Methods of testing a modified diene-containing (co)polvmer

Thermogravimetric analysis (TGA)

The 5% weight loss temperature of a modified diene-containing (co)polymer was measured to determine its thermal stability, by studying the behavior of samples of the (co)polymer by the method of simultaneous thermal analysis (STA) (combined methods of differential scanning calorimetry (DSC) and thermogravimetry (TG)) according to ISOl 1358 by using an STA 449 Jupiter NETZSCH device.

Experimental conditions : inert atmosphere (argon) at a temperature in the range of from 30°C to 600°C, a heating rate of 10°C/min.

Infrared (IR) Spectroscopy

The presence of functional groups in samples of a modified diene-containing (co)polymer was determined by IR spectroscopy.

The spectra were obtained using an FTIR spectrometer Varian Excalibur HE 3600, a Pike Miracle attenuated total reflection (ATR) accessory (crystal material - ZnSe/diamond). Scan range: 4000 to 400 cm ¹ , the number of scans was 32, the spectral resolution was 4 cm ¹ . Samples were analyzed without prior sample processing.

Nuclear magnetic resonance (NMR) method

The polymer chain microstructure of a modified diene-containing (co)polymer was determined by NMR spectroscopy of hydrogen nuclei (’H) using a Bruker Avance III device (400 MHz). A solution was prepared by dissolving a 30 mg sample in 0.6 ml of deuterated chloroform. The number of scans in ^l H nuclei was equal 32.

Gel permeation chromatography (GPC)

Molecular-weight characteristics of samples of a starting diene-containing (co)polymer and modified diene-containing (co)polymer were measured by low- temperature GPC according to ISO 16014-3 in an Agilent 1200 liquid chromatography system with a refractometric detector.

Conditions for analysis·, eluent: tetrahydrofuran; dissolution and measurement temperature: 40°C; eluent flow rate: 1.0 ml/min; column: PLgel Mixed-C (2-3 items). The calculation was made according to relative calibration of polystyrene standards (EasiVial PS-H 4ml, Agilent Technologies) using the Mark-Houwink constants for rubber: K = 0.000374, a = 0.699.

Particle-size distribution of polystyrene

The particle-size distribution of polystyrene powder was measured using a test sieve shaker HAVER EML digital plus. The used test sieves had diameters of: 2.0; 1.6; 1.0; 0.70; 0.40; 0.20 mm. Sieving time - 15 min. The weight of powder on sieves was measured by the gravimetric method.

Determination of yellowness index of polystyrene granules

The yellowness index of polystyrene granules containing a flame retardant was determined by spectroscopy in the visible spectral range with an SP62 X-Rite spectrophotometer according to ASTM D 6290-13 method.

Study conditions: The sample tube was filled with granules of a sample to the top. The tube filled with granules was placed into the center of the sensor port for measurement. The sample tube was covered with an opaque, light-blocking fixture or cap. Light source - D65 (daylight), viewing angle - 10°, taking into account the reflected light (spin). Readings of the three-color diagram (X, Y, Z) required to determine the yellowness index were obtained. The number of parallel measurements was 3.

The yellowness index was determined according to ASTM E 3013-10.

Compression of polysterene samples

The samples were compressed in a hydraulic Collin press at strength of 300 kN. A sample was previously kept in a drier at 50°C. Samples were compressed for 18 min with gradual heating to 190°C for 5 min under 50 bar; a sample was kept under pressure of 50 bar at 190°C for 3 min. Then, the sample was cooled for 10 min to 40°C under pressure of 50 bars.

Flame-resistance test

Flame resistance of samples of expandable polystyrene comprising a flame retardant was determined according to national technical requirements TT 2214-019- 53505711-2010.

Preparation of a sample: 40 mm was cut off from a molded item and discarded. Then, 5 samples were cut off with dimensions of (190±l)x(90±0.5)x(20.0±0.5) mm so that there was no a technological film formed during the formation of the block, as well as no cracks, chips and open bubbles. The cut bottom face of the samples should be smooth with sharp edges and should form right angles with side faces.

The method is based on the determination of the flame height of a burning sample for 20 sec after the removal of the source of fire.

Preparation for testing:

The device was prepared and set into the operational mode. The ventilation in the chamber was turned off. The air velocity was measured with a thermal anemometer in the exhaust tube of the test chamber. The required value was from 0.5 to 0.8 m/sec.

Before testing, the samples were conditioned for at least 14 days at a temperature of (23±5)°C and a relative air humidity of (50±20)% to constant weight. Further, a mark was placed on the sample at a distance of 150 mm from the lower edge on the front and back faces. Then the samples were vertically hooked in the burning chamber to keep the measuring mark upward, and the bottom face was positioned in the same plane with the mark of the rack holder. Then the holder with the sample was vertically moved so that the stabilizer nozzle for flame exposure touched along the bottom face of the sample.

After that, the burner was ignited, and the flame was adjusted using a template held from the side so that the height of the flame with a yellow glow was (20±1) mm. The height of the flame was checked before each exposure of the flame to the sample.

On the bottom of the test chamber, under the sample, a filter paper was placed in 2 layers into a wire box.

Testing:

The burning chamber was closed. A flaming burner turned at an angle of 45° was driven from the side to the center of the free end (face) of the sample, after which a stopwatch was started. The sample was exposed to flame for 15 seconds, after which the burner was removed, and the combustion of the sample was observed. The time was measured from the beginning of the flame exposure to the moment when the top of the flame of the burning sample reached a measuring mark of 150 mm, if before this the flame did not extinguish by itself. The tests were interrupted after 20 sec (from the beginning of the process of treating the sample with a flame), and the maximum flame height and dripping (falling out of burning fragments) was estimated.

The test was considered completed if for each of 5 tested samples, the flame height of a burning sample does not exceed the measuring mark before the 20th second expires and if burning drops when fallen (falling out of burning fragments) bum on the filter paper no more than 2 sec without causing the ignition of the filter paper.

Example 1. Preparation of a modified styrene-butadiene copolymer containing acetoxybrominated diene units (a 1% modifying system containing acetic acid)

A solution of starting styrene-butadiene copolymer SBS R 30-00 A (produced by SIBUR) in dichloromethane (10 g copolymer per 100 g dichloromethane) was filled to a 250 ml dark glass flask. After that, 0.074 g (1.2 mmol) of acetic acid was added to the flask. The solution was stirred and the bath temperature was set at 35°C. Then, a solution of 22 g (1.2 mmol) of N-bromosuccinimide in dicloromethane was prepared and dropped to the flask after which the reaction mass was stirred for 2 hours. After that, 0.5 g of a 20 mol% solution of sodium hydroxide was added to the solution, and neutralization was allowed to proceed for 30 min. The reaction mass was washed with three-fold excess of water, the resulting acetoxybrominated styrene- butadiene copolymer was precipitated with iso-propyl alcohol and dried in vacuum drying oven at 60°C under 0.5 kPa.

The resulting powder of acetoxybrominated styrene-butadiene copolymer was dissolved in 100 g of dichloromethane and placed in a 250 ml dark glass flask. The solution was stirred and the bath temperature was set at 35°C. Butanol was added in an amount of 7.5 g. The flask was then dosed with a solution of bromine in dichloromethane (18.9 g of bromine per 18.9 g of dichloromethane), and the solution was stirred for 30 min at 35°C. The reaction mass was washed with three-fold excess of distilled water.

Once the reaction completed, 20 g of a 20 mol% solution of sodium hydroxide was added to the flask, and neutralization was allowed to proceed for 60 min. The reaction mass was washed with three-fold excess of water, followed by precipitation of the resulting acetoxybrominated styrene-butadiene copolymer with isopropyl alcohol. After that, the resulting acetoxybrominated styrene-butadiene copolymer was dried by degassing the solvent at 30-95°C under pressure of 3 kPa, followed by drying in a vacuum drying oven at 70°C under 0.5 kPa.

The characteristics of the acetoxybrominated styrene-butadiene copolymer prepared according to Example 1 are given in Table 1.

Examples 2 to 7. Preparation of acetoxybrominated styrene-butadiene copolymers and benzoyloxybrominated styrene-butadiene copolymers with varying amounts of a modifying system

Examples 2-7 were carried out similarly to Example 1 , except that the amount of the modifying system was varied. Table 2 presents amounts of the modifying system.

In addition, in Example 7, the process of introducing benzoic groups into the copolymer structure ran for 8 hours at 38°C.

The characteristics of the modified styrene-butadiene copolymers prepared according to Examples 2 and 3 are given in Table 1. The characteristics of the modified styrene-butadiene copolymers prepared according to Examples 4 to 7 are given in Table 3.

Table 1. The characteristics of the modified styrene-butadiene copolymers comprising acetoxy groups

The presence of acetoxy groups in the structure of the prepared modified styrene-butadiene copolymer was confirmed by IR spectra by the appearance of an absorption band at 1740 cm ¹ .

As can be seen from the data of Table 1, the thermal stability resistance characteristics of acetoxy-modified brominated styrene-butadiene copolymer remain constant.

'H NMR spectrum of the prepared acetoxybrominated styrene-butadiene copolymer is shown in Fig.4.

Table 2. Amounts of starting materials for Examples 2 to 7

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Table 3. Characteristics of the modified styrene-butadiene copolymers comprising benzoyloxy groups

*polymer modification process ran for 8 hours at 38°C

As can be seen from the data of Table 3, the thermal stability characteristics of modified brominated styrene-butadiene copolymer gradually increase with an increase in the modification degree (Examples 4 to 7). The modification degree increases over the time of synthesis (Examples 6, 7). At the maximum amount of the modifying system, the thermal stability reaches the thermal stability of the acetoxybrominated styrene-butadiene copolymer.

Example 8 (comparative). Preparation of a brominated styrene-butadiene copolymer without a modifying system

A solution of starting styrene-butadiene copolymer SBS R 30-00 A (produced by SIBUR) in dichloromethane (10 g copolymer per 100 g dichloromethane) was filled to a 250 ml dark glass flask. The solution was stirred, and the bath temperature was set at 35°C. Butanol was added in an amount of 7.5 g. The flask was then dosed with a solution of bromine in dichloromethane (18.9 g of bromine per 18.9 g of dichloromethane), and the solution was stirred for 30 min at 35°C.

Once the reaction completed, 20 g of a 20 mol% solution of sodium hydroxide was added to the flask, and neutralization was allowed to proceed for 60 min. Then, the reaction mass was washed with three-fold excess of water, followed by precipitation of the resulting brominated styrene-butadiene copolymer with isopropyl alcohol. After that, the resulting brominated styrene-butadiene copolymer was dried by degassing the solvent at 30-95°C under pressure of 3 kPa, followed by drying in a vacuum drying oven at 70°C under 0.5 kPa.

Decomposition (5% weight loss) temperature was 212°C.

Thus, it can be noted that the decomposition temperature of non-modified brominated copolymer is significantly lower than that of the polymers according to the invention.

Example 9. Preparation of expandable polystyrene

87 parts of water and 0.43 parts of a polymerization stabilizer (a mixture of sodium pyrophosphate and magnesium sulfate) were mixed in a flask at a temperature of 25°C. A mixture of 100 parts of styrene, 0.46 part of a mixture of polymerization initiators (benzoylperoxide and tert- butyl perbenzoate), 0.62 part of a flame retardant prepared according to examples 1 and 7, and 0.21 part of a flame retardant synergist (dicumyl peroxide) were added to this mixture with stirring. The mixture was stirred for 2 hours at a temperature of up to 85°C and then heated to 115°C for 4.5 hours. At 70 minutes after the temperature in the flask reached 80°C, a 10% aqueous solution of polyvinylpyrrolidone was added to the reaction mixture. After an additional 100-120 minutes, a solution of 0.10 part of a chain transfer agent in 4.7 parts of a foaming reagent (n-heptane) was added to the reaction mass— a step of expanding polystyrene. After reaching 115°C, the flask was kept at a constant temperature for 3 hours, after which the mixture was cooled to 25°C for 3 hours.

Table 4. Particle-size distribution of polystyrene comprising a flame retardant

Modified copolymers of butadiene and styrene, obtained according to Examples

1 and 7, when introduced into polystyrene, do not affect the particle size distribution, and a stable suspension is formed with granules of the required size that completely satisfy TT 2214-019-53505711-2010 (Table 4).

Table 5 shows the results of a comparison of the yellowness index (average yellowness index) for granules of expanded polystyrene containing flame retardants according to Examples 1 and 7, and HBCD. As can be seen from the data of Table 5, although the color of expanded polystyrene containing flame retardants according to the invention (according to Examples 1, 7) is slightly higher than products with HBCD; however, the color is managed to be significantly reduced compared to the non- modified brominated flame retardant (according to Example 8).

Table 5. Comparison of the yellowness index of granules of expanded polystyrene containing flame retardants

Example 10. Preparation of acetoxybrominated styrene-butadiene copolymer by acylation of the hydroxybrominated copolymer.

A solution of a hydroxybrominated copolymer prepared from starting styrene- butadiene copolymer SBS R 30-00 A (produced by SIBUR) in dichloromethane (10 g copolymer per 100 g dichloromethane), as described in application WO2016123263, was filled to a 250 ml flask. Further, 1 g (12.7 mmol) of pyridine is added with subsequent addition of 1 g (12.7 mmol) of acetylchloride. Then, the solution was stirred and the bath temperature was set at 30°C. The reaction mass was stirred for 2 hours. After that, the reaction mass was washed with 100 ml of water, and the polymer was precipitated with isopropyl alcohol and dried in a vacuum drying oven at 60°C under 0.5 kPa.

The decomposition (5% weight loss) temperature was 212°C.

Without wishing to be bound by any theory, the authors of the present invention believe that the presence of acyloxyhalogenated diene units, in addition to the halogen atoms in the modified diene-containing (co)polymer, provides better compatibility of the (co)polymer flame retardant with the polystyrene matrix. Also, acyloxyhalogenated groups confer the flame retardant with high heat resistance.

As a result, the addition of a flame retardant to the process of suspension polymerization of styrene ensures a stable suspension, the polymerization process proceeds without deviation due to the complex effect of two types of functional groups, namely, acyloxy groups and halogen atoms which simultaneously present in the modified diene-containing (co)polymer. This provides an improved distribution of a flame retardant in the suspension in the process of suspension polymerization of styrene, thus ensuring a particle-size distribution of polystyrene that meet consumer's demands.