PRODUCING THE SAME AND USE OF THE SAME AS A FLAME

RETARDANT

Field of the Invention

The present invention relates to modified diene-containing (co)polymers, particularly, to a modified styrene-butadiene copolymer that may be used as a flame retardant for expandable polystyrene-based polymer compositions. In particular, the invention relates to a modified diene-containing (co)polymer, a method for producing the same, and use of the same as a flame retardant for polystyrene, including expandable polystyrene.

Background of the Invention

Flame retardants are widely used in articles made of various polymers and polymer compositions, for example, in expandable polystyrene articles, to provide flame retardant properties thereto [Stockholm Convention on Persistent Organic Pollutants, UNEP/POPS/POPRC.6/10, 15.10.2010] Various low molecular weight brominated compounds, for example, hexabromocyclododecane (HBCD), are normally employed as flame retardants in such polymer compositions. However, many studies have revealed a bioaccumulative potential, high toxicity and resistance to environmental exposure of HBCD [Stockholm Convention on Persistent Organic Pollutants, UNEP/POPS/POPRC.6/10, 15.10.2010, cl. 4]. This resulted in limitation of using HBCD as a flame retardant so as to reduce environmental risks.

Processing temperatures are often very high for some polymer compositions, for example, those based on expandable polystyrene [Stockholm Convention on Persistent Organic Pollutants, UNEP/POPS/POPRC.6/10, 15.10.2010, cl. 74], and hence a flame retardant may decompose during processing of a polymer composition. Meanwhile, loss of flame retardant properties of polymer compositions and formation of decomposition products, such as HBr, are observed. Consequently, it is crucial that a flame retardant is thermally stable at processing temperatures of polymer materials and meets the requirements of non-toxicity and environmental friendliness.

As an alternative to HBCD, known in the art are flame retardants that are more ecologically friendly as compared to HBCD and that are obtainable from diene- containing (co)polymers, especially styrene-butadiene copolymers. Examples of such flame retardants are brominated styrene-butadiene copolymers disclosed, for example, in application W02008021417 and in patent RU2414479.

Patent RU2414479 discloses a thermally stable brominated styrene-butadiene copolymer that can be used as a flame retardant in expanded and non-expanded polymer materials. Said brominated styrene-butadiene copolymer is characterized by a non- brominated, non-aromatic double bond content of less than or equal to 15%, based upon non-aromatic double bond content of the copolymer prior to bromination as determined by 'PI NMR spectroscopy, and a 5% weight loss temperature, as determined by thermogravimetric analysis (TGA), of at least 200°C.

The invention according to patent RU2414479 also proposes a method for producing the aforementioned thermally stable brominated copolymer, the method comprising:

a) providing a homogeneous reaction solution of a copolymer, a brominating agent, particularly, tetraalkylammonium tribromide, and a solvent;

b) maintaining the reaction solution under reaction conditions for a period of time sufficient to brominate at least 85% of non-aromatic double bonds contained in the copolymer;

c) recovering the brominated copolymer by passing a filtrate through a silica gel or an ion exchange resin layer;

d) washing the filtrate with an aqueous solution of sodium hydrosulfite to neutralize the unreacted brominating agent;

e) isolating the brominated copolymer by precipitation in methanol.

Moreover, the invention according to patent RU2414479 discloses a polymer blend comprising said thermally stable brominated styrene-butadiene copolymer, as well as a molded article comprising said polymer blend.

The said flame retardant possesses low thermal stability at high processing temperatures of expandable polystyrene, and limited compatibility of highly brominated styrene-butadiene copolymers, which may cause difficulties in obtaining a homogeneous structure of expandable polystyrene at a large thickness of articles made therefrom.

Another example of polymeric flame retardants for expandable polystyrene is hydroxybrominated styrene-butadiene copolymers that are disclosed, for example, in application WO2016123263.

The flame retardant proposed in application WO2016123263 is produced by reacting a styrene-butadiene copolymer with a quaternary ammonium tribromide to brominate 50% to 98% of the butadiene repeating units in the starting copolymer to form a partially brominated copolymer and then reacting the partially brominated copolymer with an N-haloimide compound, for example, an N-chlorosuccinimide compound or an N-bromosuccinimide compound, in the presence of water and a water- soluble solvent system to halohydrate at least a portion of the butadiene repeating units and produce a hydroxybrominated styrene-butadiene copolymer. The resultant hydroxybrominated styrene-butadiene copolymer comprises from 2 to 50 wt.% of the butadiene units that are hydroxybrominated and from 50 to 98 wt.% of the butadiene units that are brominated, and has a 5% weight loss temperature of at least 250°C.

The said flame retardant characterized by low thermal stability at high processing temperatures of expandable polystyrene, and the absence of functional groups capable of absorbing HBr that releases at high temperatures.

In addition, the method for producing a flame retardant proposed in said invention is characterized by large amount of time spent in the step of producing a hydroxybrominated styrene-butadiene copolymer, and in the step of isolating the same from the reaction mass, and the need for using expensive reactants, in particular, the N- haloimide.

A brominated and epoxidized styrene-butadiene copolymer according to patent RU2530021 (selected as a prototype) that is used as a flame retardant for expandable polystyrene is the closest to the flame retardant under development and the method for producing the same.

In accordance with the known invention, the flame retardant is produced by a process comprising:

a) epoxidizing a starting styrene-butadiene copolymer that has a molecular weight of at least 700 g/mol so that at least a portion of the non-conjugated carbon- carbon double bonds is epoxidized;

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

The flame retardant produced according to said invention is characterized by a molecular weight of at least 1500 g/mol, a bromine content of at least 35 wt.%, and a five percent (5%) weight loss temperature of at least 180°C.

However, even though said flame retardant comprises epoxide groups that are capable of absorbing HBr that releases at high processing temperatures of expandable polystyrene-based polymer compositions, such a flame retardant exhibits poor compatibility with polystyrene.

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

In this connection, one of the promising trends is the development of a flame retardant based on a diene-containing (co)polymer that should be thermally stable, consistent with requirements of environmental friendliness, and that should not influence the process of polymerization and granulation of polystyrene, and simultaneously should provide excellent flame retardant properties to polystyrene, including expandable polystyrene.

Description of drawings

Figures 1-2 are set out in order to clarify the engineering solutions disclosing the essence of the present invention.

Fig. 1 represents a flow chart showing a sequence of steps of producing a modified diene-containing (co)polymer in accordance with the present invention.

Fig. 2 represents’H NMR spectrum of the produced modified diene-containing (co)polymer comprising epoxide groups, hydroxyl groups, amino groups, and halogen atoms.

Summary of the Invention

It is an object of the present invention to develop a modified diene-containing (co)polymer that can be used as a flame retardant for expandable polystyrene, and to develop a method for producing the same.

The technical result of the present invention is an increase in thermal stability of modified diene (co)polymers, in particular, a rise in a 5% weight loss temperature, which is at least 180°C, wherein (co)polymers produced according to this invention are characterized by a molecular weight of at least 1500 g/mol, a halogen content of at least 35 wt.%, relative to the total weight of the (co)polymer, and do not affect the process of polymerization and granulation of polystyrene.

Said technical result is achievable by producing a modified diene-containing (co)polymer comprising epoxide groups, hydroxyl groups, amino groups, along with halogen atoms, which is obtained by epoxidizing a starting diene-containing (co)polymer and further performing the subsequent steps of reacting with an aminating agent and a halogenating agent.

The authors of the present invention have surprisingly discovered that the modified diene-containing (co)polymer comprising epoxide groups, hydroxyl groups, amino groups, and halogen atoms, is thermally stable and does not affect the process of polymerization and granulation of polystyrene.

The instant invention permits obtaining a modified diene-containing (co)polymer comprising epoxide groups, hydroxyl groups, amino groups, and halogen atoms that can be used as a flame retardant in various polymer compositions, for example, those based on polystyrene, including expandable polystyrene.

Detailed Description of the Invention

In accordance with the present invention, the structure of the modified diene- containing (co)polymer contains halogen atoms, at least one epoxide group, at least one hydroxyl group, and at least one amino group; the (co)polymer having a 5% weight loss temperature of at least 180°C, a weight-average molecular weight of at least 1500 g/mol, and a halogen content of at least 35 wt.%, relative to the total weight of the (co)polymer.

The modified diene-containing (co)polymer produced according to the invention is a thermally stable 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 a plurality of non-conjugated carbon- carbon double bonds, wherein at least two double bonds (but less than all of the non- conjugated carbon-carbon double bonds) are modified, and the modified diene- containing (co)polymer comprises at least 35 wt.%, preferably at least 60 wt.%, more preferably at least 75 wt.% of halogen, relative to the total weight of the (co)polymer, at least one epoxidized non-conjugated carbon-carbon double bond, at least one hydroxyhalogenated non-conjugated carbon-carbon double bond, and at least one hydroxyaminated non-conjugated carbon-carbon double bond.

“Thermal stability”, as used herein, means a 5% weight loss temperature of the modified diene-containing (co)polymer determined by the thermogravimetric analysis (TGA) method described below.

The obtainable thermally stable modified diene-containing (co)polymer comprises at least one epoxide group, wherein the content of epoxide groups in the obtainable modified diene-containing (co)polymer is from 0.01 to 5 wt.%, preferably from 0.03 to 3 wt.%, more preferably from 0.5 to 1 wt.%, relative to the total weight of the (co)polymer.

The obtainable thermally stable modified diene-containing (co)polymer comprises at least one hydroxyl group, wherein the content of hydroxyl groups in the obtainable modified diene-containing (co)polymer is from 0.01 to 0.5 wt.%, preferably from 0.02 to 0.1 wt.%, more preferably from 0.03 to 0.08 wt.%, relative to the total weight of the (co)polymer.

The thermally stable modified diene-containing (co)polymer obtainable according to the invention comprises at least one amino group, wherein the content of amino groups in the obtainable diene-containing (co)polymer is from 0.01 to 5 wt.%, preferably from 0.05 to 3 wt.%, more preferably from 1 to 2 wt.%, relative to the total weight of the (co)polymer.

The presence of three types of functional groups, in addition to halogen atoms, in the modified diene-containing (co)polymer allows solving several problems, specifically, amino groups transform at elevated temperatures to nitrogen-containing compounds that efficiently block combustion by releasing nitrogen oxides that displace oxygen at a surface of a burning material, which is a mechanism of combustion control. The epoxide groups function as absorbers of HBr, which latter, as mentioned above, may be discharged during processing of polymers and polymer compositions comprising a flame retardant at elevated temperatures. In their turn, the hydroxyl groups render the (co)polymer polar and hydrophilic.

Therefore, the introduction of a flame retardant into the process of suspension polymerization of styrene causes the formation of a stable suspension, the polymerization of styrene runs without deviations due to combined influence of four types of functional groups, namely, the epoxide group, the hydroxyl group, the amino group, and the halogen atoms that are simultaneously present in the modified diene- containing (co)polymer. This results in better distribution of a flame retardant within the suspension during the process of suspension polymerization of styrene thereby allowing the production of polystyrene with a particle-size distribution that satisfies the consumers’ needs.

In this connection, the 5% weight loss temperature of the modified diene- containing (co)polymer is at least 180°C, preferably at least 200°C, more preferably at least 220°C.

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

wherein R ₁ -R ₃ are the same or different, and may be hydrogen or a hydrocarbon group having 1 to 6 carbon atoms, for example, an alkyl group; Hal is a halogen selected from chlorine, bromine or iodine; k, m, 1, h, p may be the same or different and may be preferably l<k<37, l<m<19, 2<(l+p)<3660, 1 <h< 15, more preferably 6<k<12, 3<m<6, 610<(l+p)<1220, 2<h<10, most preferably 7<k<10, 4<m<5, 730<(l+p)<980,

3<h<5; n is the number of polymer units in a chain that is 50<n<450, preferably 100<n<350, more preferably 140<n<250.

Polymers and copolymers of conjugated dienes may be used as starting diene- containing (co)polymers.

Within the context of the present invention, the organic solvent is such that it is liquid and inert under the production conditions of the modified diene-containing (co)polymer.

In another embodiment, the present invention relates to a method for producing a modified diene-containing (co)polymer, comprising the following steps:

a) a dissolving step, (optionally) comprising preliminarily grinding a starting diene-containing (co)polymer, and then dissolving the same in a solvent;

b) an epoxidizing step, comprising adding an epoxidizing agent to the solution of the starting diene-containing (co)polymer in a solvent produced in step a);

c) a neutralizing and separating step, comprising adding an aqueous solution of a neutralizing agent to the reaction mass produced in step b), and separating the aqueous layer and the organic layer;

d) an aminating step, comprising adding an animating agent and optionally an organic tin catalyst to the organic layer obtained in step c);

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

f) a halogenating step, comprising adding a halogentating agent, water, and optionally an aliphatic alcohol to the organic layer obtained in step e);

g) a neutralizing and separating step, comprising adding an aqueous solution of a neutralizing agent to the reaction mass produced in step f), and separating the aqueous layer and the organic layer;

h) an isolating step, comprising precipitating or degassing the modified diene- containing (co)polymer from the organic layer obtained in step g);

i) a step of filtering and subsequent drying of the isolated modified diene- containing (co)polymer.

Dissolving step a)

This step optionally comprises preliminarily grinding a starting diene-containing (co)polymer, and then dissolving the same in a solvent under stirring.

If necessary, the starting diene-containing (co)polymer is ground by any prior art methods, for example, by means of grinders (in particular, knife grinders, hammer grinders, rotary grinders), mills (for example, jet-type mills or screw-type mills), and by other methods known to a person skilled in the art.

The starting diene-containing (co)polymer may be a polymer and copolymer of conjugated dienes.

Suitable conjugated dienes are conjugated dienes having from 4 to 12 carbon atoms, for example, 1,3 -butadiene, 2-methyl- 1,3-butadiene (isoprene), 2 -ethyl-1, 3- butadiene, 2,3-di(Cl-C5 alkyl)- 1,3 -butadienes, such as 2, 3 -dimethyl- 1,3 -butadiene, 2,3- diethyl- 1,3 -butadiene, 2-methyl-3-ethyl-l, 3-butadiene, 2-methyl-3-isopropyl-l,3- dutadiene, phenyl- 1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene, 2-methyl-pentadiene, 4-methyl-pentadiene, or mixtures thereof. 1,3 -Butadiene or isoprene, or a mixture thereof are preferably used.

Suitable comonomers in the starting diene-containing (co)polymer are vinyl aromatic compounds, such as styrene, a-methylstyrene, ortho-, meta-, and para- methylstyrene, 3 -vinyl toluene, ethyl vinylbenzene, 4-cyclohexylstyrene, para-tert- butylstyrene, methoxystyrenes, vinyl mesethylene, divinylbenzene, 1 -vinylnaphthalene, 2,4,6-trimethylstyrene, or mixtures thereof. Styrene or a-methylstyrene, or mixtures thereof are preferably used.

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

(Co)polymers, such as butadiene polymers, styrene-butadiene copolymers, and styrene-butadiene-isoprene copolymers, most preferably the styrene-butadiene copolymers, which may be styrene/butadiene diblock and triblock copolymers, may preferably be used as the diene-containing (co)polymers.

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

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, most preferably from 20000 to 50000 g/mol, and a polydispersity of from 0.8 to 3, more preferably from 1 to 1.8, most preferably from 1.1 to 1.5, and have an amount of 1,2-units of at least from 10 to 100 wt.%, preferably at least from 50 to 99 wt.%, more preferably from 60 to 80 wt.%, relative to the polybutadiene part of the (co)polymer.

When dissolving a starting diene-containing (co)polymer, the stirring may be carried out by any prior art method, for example, by means of an agitator, 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 not limited to, organic solvents, preferably having purity of 99% or more, and being 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. Preferable organic solvents are such that are liquid under the conditions of modifying a starting diene-containing (co)polymer and that are inert under the conditions of running step b) of epoxidizing the starting diene-containing (co)polymer. Advantageously, tetrahydrofuran, chloroform, dichloromethane, dichloroethane, cyclohexane, and toluene are used as the solvent; tetrahydrofuran, chloroform, dichloromethane are the most preferred.

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

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

The mass obtained after the above-described dissolving step is a solution of the starting diene-containing (co)polymer in an organic solvent.

Epoxidizing step b)

The epoxidizing step b) comprises adding an epoxidizing agent to the solution of the starting diene-containing (co)polymer in a solvent produced in step a), as a result of which non-conjugated carbon-carbon double bonds become oxidized to form epoxide groups.

According to the present invention, pure substances containing active oxygen, as well as solutions of such substances, or mixtures thereof, in organic solvents, where the epoxidizing agent comprises from 10 to 50 wt.%, preferably from 15 to 30 wt.%, more preferably from 20 to 25 wt.%, are employed as the epoxidizing agent.

In accordance with the present invention, suitable epoxidizing agents are, but not limited to, peracids, for example, performic acid, peracetic acid, meta-chloroperbenzoic acid, and peroxides, for example, hydrogen peroxide, or mixtures thereof, including in the presence of catalysts, for example, molybdenum or tungsten derivatives.

The epoxidizing agent is dissolved in an organic solvent or in a mixture of organic solvents, preferably having purity of 99% or more, being an 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. The epoxidizing agent is preferably added in the form of a solution thereof in the same solvent that is used in step a) to dissolve the starting diene- containing (co)polymer.

The epoxidizing agent is used in an amount sufficient to epoxidize not more than 6 mol.% of non-aromatic double bonds, preferably not more than 2.5 mol. % of nonaromatic double bonds, more preferably not more than 0.5 mol.% of non-aromatic double bonds.

During the epoxidizing step, the epoxidizing agent or a solution thereof is advantageously dosed at a rate from 0.80 to 50 ml/min, preferably from 1 to 10 ml/min, more preferably from 1.5 to 5 ml/min. A very high dosing rate causes crosslinking of the (co)polymer in the reaction mass, while a low dosing rate increases considerably the synthesis time.

The epoxidizing step is performed in any prior art batch or continuous equipment. Suitable equipment is, but not limited to, a continuous stirred-tank reactor, a batch stirred-tank reactor, an autoclave equipped with a mixer.

The epoxidizing step is carried out at a temperature of from (-20)°C to 100°C, preferably from (-10)°C to 50°C, more preferably from 0°C to 20°C, and at atmospheric pressure.

The time of the epoxidizing step may be any time sufficient to achieve the required degree of epoxidation of the starting diene-containing (co)polymer described above. Advantageously, the time of the epoxidizing step 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 after step b) contains a partially epoxidized diene- containing (co)polymer.

Neutralizing and separating step c)

This step comprises neutralizing the reaction mass obtained in step b), which comprises a partially epoxidized diene-containing (co)polymer, by adding a solution of a neutralizing agent and then washing the neutralized reaction mass with water and separating the aqueous layer and the organic layer comprising the partially epoxidized diene-containing (co)polymer.

Aqueous basic solutions that are known in the art, for example but not limited to, solutions of sodium hydroxide, sodium thiosulfate, sodium bisulfite, sodium carbonate, and other similar compounds are used as the neutralizing agent.

The mole ratio of an amount of the neutralizing agent to an amount of the added epoxidizing agent is usually from 1:1 to 3:1, preferably from 1 :1 to 2:1, more preferably 1:1.

The neutralizing process is preferably performed at a temperature from 15 to 50°C, preferably from 20 to 40°C, more preferably from 25 to 30°C, and at atmospheric pressure.

The washing with water is carried out by means of at least one-fold, preferably at least two-fold, more preferably at least three-fold excess of water relative to the reaction mass volume subjected to the neutralization, whereby the reaction mass is divided into two layers: an organic layer comprising the partially epoxidized diene- containing (co)polymer and an aqueous layer.

The organic layer and the aqueous layer are separated by means of any prior art method, for example, through a separating funnel, a separator, a settling tank.

Aminating step d)

The aminating step d) comprises adding an aminating agent and optionally an organic tin catalyst to the organic layer obtained in step c), which comprises the partially epodixized diene-containing (co)polymer.

Suitable animating agents are, but not limited to, primary amines, for example, monoethanolamine, methylamine, secondary amines, for example, diethylamine, dimethylamine, tertiary amines, for example, triethylamine, as well as pyridine, ammonia, phenylenediamines, hexamethylenediamine, aniline. Secondary amines, namely diethylamine, dimethylamine, are preferably used as the animating agent.

Suitable organic tin catalysts are, but not limited to, dibutyltin dilaurate, dioctyltin di(2-ethylhexanoate), dioctyltin dithioglycolate, dioctyltin dilaurate, dioctyltin oxide, dibutyltin diacetate, monobutyltin oxide, and dioctyltin stanoxane.

The epoxidized diene-containing (co)polymer:aminating agentorganic tin catalyst mole ratio is from 1 :0.01 :0.08 to 1 :1 :8, more preferably from 1 :0.05:0.4 to 1 :0.5:4, most preferably from 1 :0.09:0.75 to 1:0.11:0.85.

The animating agent is used in an amount suitable to aminate not more than 99 mol.% of epoxidized units, preferably not more than 50 mol.% of epoxidized units, more preferably not more than 30 mol.% of epoxidized units.

During the animating step, the animating agent or a solution thereof is advantageously dosed at a rate from 0.80 to 50 ml/min, preferably from 1 to 10 ml/min, more preferably from 1.5 to 5 ml/min.

The aminating step is performed in any known from the prior art batch or continuous equipment. Suitable equipment is, but not limited to, a continuous stirred- tank reactor, a batch stirred-tank reactor, an autoclave equipped with a mixer.

The aminating step is carried out at a temperature of from (-20)°C to 100°C, preferably from (-10)°C to 50°C, more preferably from 0°C to 20°C, and at atmospheric pressure.

The aminating step may have any duration sufficient to achieve the required degree of amination of the starting diene-containing (co)polymer described above. Advantageously, duration of the aminating step is at least 30 min, at least 60 min, at least 180 min, at least 240 min, at least 300 min, at least 360 min, at least 420 min.

The reaction mass obtained after the aminating step d) contains a partially epoxidized and aminated diene-containing (co)polymer.

Neutralizing and separating step e) This step comprises neutralizing the reaction mass obtained in step d), which comprises a partially epoxidized and animated diene-containing (co)polymer, by adding a solution of a neutralizing agent and then washing the neutralized reaction mass with water and separating the aqueous layer and the organic layer comprising the partially epoxidized and animated diene-containing (co)polymer.

Aqueous basic solutions that are known from the art, for example but not limited to, sodium hydroxide, sodium thiosulfate, sodium bisulfite, and sodium carbonate aqueous solutions, are used as the neutralizing agent.

The mole ratio of an amount of the neutralizing agent to an amount of the added animating agent is usually from 1 :1 to 3:1, preferably from 1 : 1 to 2:1 , more preferably 1:1.

The neutralizing process is preferably performed at a temperature from 15 to 50°C, preferably from 20 to 40°C, more preferably from 25 to 30°C, and at atmospheric pressure.

The washing with water is carried out by means of at least one-fold, preferably at least two-fold, more preferably at least three-fold excess of water relative to the reaction mass volume subjected to the neutralization, whereby the reaction mass is divided into two layers: an organic layer comprising the partially epoxidized and animated diene-containing (co)polymer and an aqueous layer.

The organic layer and the aqueous layer are separated by means of any prior art method, for example, through a separating funnel, a separator, a settling tank.

Halogenating step j)

The halogenating step f) comprises adding a halogenating agent and optionally an aliphatic alcohol to the organic layer obtained in step e), which latter comprises the partially epoxidized and aminated diene-containing (co)polymer.

Chlorine, bromine or iodine are used as a halogen in the halogenating agent; bromine is preferably used as the halogen.

Therefore, elemental bromine (Br2) as such, and a solution in an organic solvent having a bromine content of not more than 70 wt.%, more preferably not more than 60 wt.%, most preferably not more than 50 wt.% are preferably used as the halogenating agent.

Suitable halogenating agents also are, but 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.

Elemental bromine (Br2) and quaternary ammonium bromides or quaternary phosphonium bromides are preferably used as the halogenating agent. At that, elemental bromine reacts with epoxide groups in the presence of water thereby opening epoxide rings and forming hydroxybrominated diene units, and use of a quaternary ammonium bromide or quaternary phosphonium bromide allows avoiding essential substitution of hydrogen with bromine at tertiary and/or allyl carbon atoms, which, in its turn, affects thermal stability of the resultant modified diene-containing (co)polymer.

Alcohols having from 1 to 6 carbon atoms, for example but not limited to, those selected from the group consisting of methanol, ethanol, propanol, iso-propanol, butanol, iso-butanol, pentanol or hexanol, are used as the aliphatic alcohol. Propanol, butanol, iso-butanol, pentanol, more preferably butanol, iso-butanol and pentanol, or mixtures thereof are used as the aliphatic alcohol.

The starting diene-containing (co)polymer:halogenating agenhaliphatic alcohol mole ratio 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. At that, when elemental bromine and a quaternary ammonium bromide or a quaternary phosphonium bromide are jointly used, the ratio of elemental bromine :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 halogenating agent and an aliphatic alcohol, if used, may be added to the organic layer obtained in the step e) in any order. Advantageously, an aliphatic alcohol is first added to the organic layer comprising the partially epoxidized and aminated diene-containing (co)polymer, and then the halogenating agent is added. At that, when a quaternary ammonium bromide or quaternary phosphonium bromide and elemental bromine are jointly used as the halogentating agent, the whole volume of quaternary ammonium bromide or quaternary phosphonium bromide in the form of its solution in an organic solvent is added to the reaction mass.

Elemental bromine is preferably added in the form of its solution in an organic solvent by dosing the solution into the reaction mass at a rate from 0.80 to 50 ml/min, preferably from 1 to 10 ml/min, more preferably from 1.5 to 5 ml/min. A very high dosing rate causes local overheating of the reaction mass and increases its viscosity, which, in its turn, may generate a modified diene-containing (co)polymer with a low (less than 35 wt.%) content of halogen atoms.

Also, the addition of the whole volume of the elemental bromine (!¾) solution to the solution obtained in step e) may cause crosslinking of the (co)polymer and local overheating of the reaction mass, an increase in viscosity of the reaction mass, which may generate a modified diene-containing (co)polymer with a low (less than 35 wt.%) content of halogen atoms, too.

The halogenating agent may be dissolved in an organic solvent or a mixture thereof, preferably having purity of 99% or more, and being an 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. It is preferable to add the halogenating agent in the form of its solution in the same solvent as the one used in step a) to dissolve the starting diene-containing (co)polymer.

The halogenating step is performed in any known from the prior art batch or continuous equipment. Suitable equipment is, but not limited to, a continuous stirred- tank reactor, a batch stirred-tank reactor, an autoclave equipped with a mixer that are designed to work with highly corrosive media.

Advantageously, the step of halogenating the partially epoxidized and aminated diene-containing (co)polymer obtained in step e) is carried out with no exposure to light, for example, by conducing the modifying process in vessels of darkened glass, by wrapping the reactor with foil, or by conducting the process in metal reactors so as to reduce probability of non-selective photocatalytic halogenation reactions.

The halogenating step is performed at a temperature from 0 to 50°C, preferably from 20 to 45°C, more preferably from 30 to 40°C, and at atmospheric pressure. After adding the halogenating agent, the reaction mass is stirred at a rate from 50 to 600 rpm, preferably from 100 to 500 rpm, more preferably from 200 to 300 rpm.

The halogenating step may have any duration sufficient to achieve the required degree of halogenation of the acyloxyhalogenated diene-containing (co)polymer described above. Advantageously, duration 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 produced in step f) contains the target product, i.e. the modified diene-containing (co)polymer comprising acyloxyhalogenated diene units and halogen atoms.

The halogenated reaction mass obtained after step f) contains the target product, i.e. the modified diene-containing (co)polymer comprising epoxide groups, hydroxyl groups, amino groups, and halogen atoms.

Neutralizing and separating step g)

This step comprises neutralizing the reaction mass obtained in step f), which comprises the modified diene-containing (co)polymer, by adding a solution of a neutralizing agent and then washing the neutralized reaction mass with water and separating the aqueous layer and the organic layer comprising the modified diene- containing (co)polymer.

Aqueous basic solutions that are known from the art are, for example but not limited to, sodium hydroxide, sodium thiosulfate, sodium bisulfite, sodium carbonate solutions are used as the neutralizing agent.

The mole ratio of an amount of the neutralizing agent to an amount of the added halogenating agent is usually from 1 :1 to 3:1, preferably from 1 :1 to 2:1, more preferably 1:1.

The neutralizing process is preferably performed at a temperature from 15 to 50°C, preferably from 20 to 40°C, more preferably from 25 to 30°C, and at atmospheric pressure.

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

The organic layer and the aqueous layer are separated by means of any prior art method, for example, through a separating funnel, a separator, a settling tank.

Isolating step h)

If the method for producing the modified diene-containing (co)polymer is carried out, in accordance with one of the embodiments of the present invention, through a step of precipitating the modified diene-containing (co)polymer to be obtained, a precipitant alcohol is added to the organic layer obtained in step g), which contains the modified diene-containing (co)polymer, so as to isolate the modified diene- containing (co)polymer produced in step f). The precipitant alcohol modified diene- containing (co)polymer mass ratio is between 15:1 and 1:1, preferably between 10:1 and 3:1, more preferably between 5 : 1 and 4:1.

Suitable precipitant alcohols are, but not limited to, aliphatic alcohols having 1 to 4 carbon atoms. Examples of such alcohols are, but not limited to, methanol, ethanol, propanol, iso-propanol, butanol, iso-butanol. Methanol and ethanol are preferably used as the precipitant alcohols.

If the method for producing the modified diene-containing (co)polymer is carried out, in accordance with one of the embodiments of the present invention, through a step of degassing the modified diene-containing (co)polymer to be obtained, then the isolating step h) comprises adding water to the organic layer obtained in step g) and subsequently distilling the water-solvent mixture at an elevated temperature and reduced pressure in order to isolate the target modified diene-containing (co)polymer and to remove therefrom water and/or water vapor, the solvent and/or vapor thereof.

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

At that, the amount of 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 during its addition to the system is not more than 30°C, preferably not more than 25°C, more preferably not more than 20°C. If the temperature of water used is over 30°C, the solvent may boil and then vaporize violently, which, in its turn, may change physical and mechanical characteristics of the modified diene-containing (co)polymer to be obtained. Degassing is performed in any suitable prior art equipment, particularly, in apparatuses capable of providing good stirring, heat exchange, and capable of maintaining reduced pressure. Examples of such apparatuses are, but not limited to, continuous or batch apparatuses equipped with a mixer and a jacket.

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

Pressure in the degassing step is maintained at a level of less than 800 mbar, preferably less than 300 mbar, more preferably less than 100 mbar.

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

Filtering and drying step i)

In order to purify the modified diene-containing (co)polymer from solvent and precipitant alcohol residues, the filtering and drying step i) comprises filtering by means of any prior art apparatuses, for example, filters provided with porous filtering partitions, nutsch filters, and other filters that are known from the prior art.

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

For the purposes of removing water and/or water vapor, the solvent and/or vapor thereof from the produced modified diene-containing (co)polymer, said (co)polymer is subjected to drying. The modified diene-containing (co)polymer may be dried by physical methods that are conventionally employed for separating and purifying organic substances (for example, distillation of a solvent at a reduced pressure, drying in a vacuum drying oven), and also by means of drying agents that remove moisture through adsorption, formation of hydrates, or a chemical reaction with water and solvents.

Drying is preferably performed at a temperature from 50°C to 105°C and at a pressure from 1 to 20 kPa.

The invention is explained in detail below with reference to Fig. 1, which shows a flow chart of producing the modified diene-containing (co)polymer, wherein 101 is a starting diene-containing (co)polymer dissolving unit, 102 is a starting diene-containing (co)polymer epoxidizing unit, 103 is a neutralizing and separating unit, 104 is an animating unit, 105 is a neutralizing and separating unit, 106 is a halogenating unit, 107 is a neutralizing and drying unit, 108 is an isolating unit, 109 is a filtering unit, 110 is a drying unit.

According to the proposed method, the optionally ground starting diene- containing (co)polymer (1) is directed to the dissolving unit 101, where it mixes with an organic solvent (2) to form a solution of the starting diene-containing (co)polymer (3). Said (co)polymer solution (3) then enters the epoxidizing unit 102, into which latter an epoxidizing agent (4) is also introduced. Thereafter, the partially epoxidized diene- containing (co)polymer (5) produced in the unit 102 is directed to the neutralizing and separating unit 103, into which a neutralizing agent (6) is supplied, followed by feeding water (7) to wash the neutralized reaction mass, and then an organic layer (9) comprising the partially epoxidized diene-containing (co)polymer is separated from an aqueous layer (8). The organic layer (9) comprising the partially epoxidized diene- containing (co)polymer enters the animating unit 104, into which an animating agent (10) and an organic tin catalyst (11), if used, are also introduced to form reaction mass (12) comprising the partially epoxidized animated diene-containing (co)polymer. Thereafter, the obtained reaction mass (12) comprising the partially epoxidized animated diene-containing (co)polymer enters the neutralizing and separating unit 105, into which a neutralizing agent (13) is fed, followed by feeding water (14) to wash the neutralized reaction mass, and then an organic layer (16) comprising the epoxidized animated diene-containing (co)polymer is separated from an aqueous layer (15). The organic layer (16) comprising the epoxidized animated diene-containing (co)polymer is directed to the halogenating unit 106, into which a halogenating agent (17) and an aliphatic alcohol (18) are also fed, thereby producing reaction mass comprising a modified diene-containing (co)polymer that includes epoxide groups, hydroxyl groups, amino groups, and halogen atoms. Thereafter, the produced reaction mass (19) comprising the modified diene-containing (co)polymer enters the neutralizing and separating unit 107, into which a neutralizing agent (20) is fed, followed by feeding water (21) to wash the neutralized reaction mass, and then an organic layer (23) comprising the modified diene-containing (co)polymer is separated from an aqueous layer (22). The organic layer (23) comprising the modified diene-containing (co)polymer then enters the isolating unit 108. The isolated modified diene-containing (co)polymer (24) is sequentially fed to the filtering unit 109 and (25) to the drying unit 110 to produce a final product, i.e. the modified diene-containing (co)polymer (26). The method for producing the modified diene-containing (co)polymer may also include an organic solvent regenerating unit, wherein said solvent is recycled back to the starting diene-containing (co)polymer dissolving unit 101 (not shown in Fig. 1).

The flow chart represented in Figure 1 is an example of carrying out the present invention and does not intend to limit the same.

Modified diene-containing (co)polymers produced in accordance with the present invention may be used as flame retardants in various polymers and polymer compositions, for example, those based on expandable polystyrene, to provide flame retardant properties thereto. Meanwhile, flame retardants must be compatible with a polymer or a polymer composition.

According to this invention, the modified diene-containing (co)polymer is introduced into a polymer or a polymer composition in the production step. For instance, the modified diene-containing (co)polymer is introduced into expandable polystyrene in the step of producing the same according to a method that comprises obtaining polystyrene by polymerizing styrene in the presence of a polymerization initiator, polymerization stabilizer, etc., and then performing a step of expanding the resultant polystyrene (for example, as disclosed in patent US5086078).

In another embodiment, the present invention relates to expandable polystyrene comprising said modified diene-containing (co)polymer as a flame retardant. At that, the content of the modified diene-containing (co)polymer used as a flame retardant must not be less than 0.5 parts by weight, preferably not less than 0.7 parts by weight, more preferably not less than 1 part by weight per 100 parts by weight of a polymer, otherwise efficacy of improvement of fireproofing characteristics of the produced polymer or polymer composition, particularly, expandable polystyrene or a composition based thereon, decreases.

Moreover, in yet another embodiment, polymer compositions, for example, those based on expandable polystyrene comprising the modified diene-containing (co)polymer according to the present invention, may also include the following conventional additives that permit achieving the required complex of engineering, physical-mechanical and performance characteristics, for example but not limited to, antistatics, stabilizers, dyes, lubricants, fillers, adhesion reducing agents.

In accordance with the present invention, expandable polystyrene compositions may be used for manufacturing a wide range of articles, such as building heat insulation and sound insulation, specifically, heat- and sound-insulating boards, permanent shuttering, vehicle components, floating articles, and as feedstock for expandable polystyrene blocks required for construction of roads and bridges, and packing of household appliances.

The modified diene-containing (co)polymer produced according to the present invention may be used as a flame retardant in expandable polystyrene, because it is characterized by high thermal stability, namely, the five percent weight loss temperature of at least 180°C as determined by thermogravimetric analysis, does not influence the process of polymerization and the process of polymer granulation, which is confirmed by the particle-size distribution of the produced polystyrene. Furthermore, the flame retardant obtained according to this invention provides expandable polystyrene with flame retardant properties, which permits labelling expandable polystyrene, which latter comprises the flame retardant proposed according to the present invention, as a moderately flammable material with B2 flammability class (in conformity with cl. 7, art. 13 of the Technical Regulations on Fire Safety Requirements (Federal Act No. 123 of 22.07.2008, as amended on 29.07.2017)).

The invention will be explained by examples below. The examples are given solely for illustrative purposes and are not intended to limit the scope of the present disclosure.

Embodiments of the Invention

Methods of studying a modified diene-containing (coipolvmer

Thermogravimetric analysis (TGA)

In order to determine thermal stability of the modified diene-containing (co)polymer to be obtained, the 5% weight loss temperature is measured by studying thermal behavior of (co)polymer samples via the simultaneous thermal analysis (STA) (combined methods of differential scanning calorimetry (DSC) and thermogravimetry (TG)) according to ISOl 1358 using an STA 449 Jupiter NETZSCH apparatus.

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

Nuclear magnetic resonance (NMR) method

A polymer chain microstructure of the samples of the modified diene-containing (co)polymer is determined by 'H NMR spectroscopy using a Bruker Avance III (400 MHz) apparatus. In order to prepare a solution for the study, a 30 mg sample is dissolved in 0.6 ml of deuterated chloroform. The number of scanning on 'H nuclei is 32.

Gel permeation chromatography (GPC)

Molecular weight characteristics of the samples of the starting diene-containing (co)polymer and the modified diene-containing (co)polymer are determined by low- temperature GPC in conformity with ISO 16014-3 on an Agilent 1200 liquid chromatograph with a refractometric detector.

Analysis conditions : the eluent is tetrahydrofuran; the dissolution and measurement temperature is 40°C, the eluent flow rate is 1.0 ml/min; the column is PLgel Mixed-C (2-3 pieces). The calculation is performed by relative calibration on polystyrene standards (EasiVial PS-H 4 ml, Agilent Technologies), using the Mark- Houwink constants for the copolymer: K = 0.000374, a = 0.699.

Particle-size distribution of polystyrene

Particle-size distribution of polystyrene powder is determined on a HAVER EML digital plus sizing screen. A kit of sieves having a mesh size of 2.0; 1.6; 1.0; 0.70; 0.40; 0.20 mm is used for sizing. Sizing time is 15 min. The weight of powder on the sieves is determined by a gravimetric method.

Flame resistance test

Flame resistance of the samples of expanded polystyrene containing a flame retardant is determined in compliance with technical requirements TT 2214-019- 53505711-2010.

Preparation of a sample : 40 mm is cut off a molded part and thrown away as waste. 5 samples having the dimensions of (190±1) ^c (90±0,5) ^c (20,0±0,5) mm are cut in such a manner so that technological film, cracks, chips, and open bubbles didn’t form during the block formation,. The lower face of the sample is cut smoothly, has sharp edges, and forms right angles with lateral faces.

The method is based on determination of flame height of a burning sample within 20 s after removal of a flame source.

Preparation for the test:

The apparatus is prepared and brought to the operating mode. Ventilation is switched off in the chamber. Air velocity is measured by a heat-loss anemometer in a vent pipe of the test chamber. The required value is from 0.5 to 0.8 m/s.

Prior to testing, the samples are conditioned for at least 14 days at a temperature of (23±5)°C and relative air humidity of (50±20)% until constant weight is obtained.

The sample is then marked at a distance of 150 mm from the lower edge on the front side and on the reverse side. The samples are hung vertically in a fastener in a firing chamber, with the measuring mark on the top, and the lower edge is positioned in the same plane with the mark of a rack holder. The holder with a sample is moved vertically such that the stabilizer attachment for exposure to flame passes tangentially along the lower edge of the sample.

A burner is ignited, and flame is adjusted by means of a template hold on one side such that the flame height of yellow colour is (20±1) mm. The flame height is checked before each exposure of a sample to flame.

Filter paper is put in 2 layers under a sample in a wire box on the bottom of the test chamber.

Test procedure:

The firing chamber is closed. A burner with flame turned at an angle of 45° is brought to the center of the free end (edge) of the sample, and a stopwatch is turned on. The sample is exposed to flame for 15 s, thereafter the burner is drawn aside, and burning of the sample is observed. Simultaneously, the time period is measured from the beginning of exposure to flame till the moment when the top of flame of the burning sample reaches the 150 mm mark, if the flame has not died out before. The test is interrupted after 20 s (after the flame treatment of the sample began) and maximum flame height and drippage (dropping of burning fragments) are assessed.

The test is recognized as having been passed, if the top of flame of each one of the 5 tested samples does not go beyond the measuring mark after the 20 ^th second, and when burning droplets fall (burning fragments drop), they bum on the filter paper for not longer than 2 s, and do not cause the filter paper to bum.

Example 1 (according to the invention). Production of a modified styrene- butadiene copolymer comprising 0.05 wt.% of hydroxyaminated butadiene units

A solution of the starting styrene-butadiene copolymer (4 g in 40 g of dichloromethane) is cooled under stirring to 0-5°C. 0.4 g of a 10 wt.% solution of m- chloroperoxybenzoic acid in dichloromethane (1 mol of the acid per 1 mol of epoxidized diene units) are dosed to the cooled copolymer solution. The temperature of the cooling bath is maintained at 0-5 °C. After the whole volume of the acid has been added, the reaction mass is stirred at the predetermined temperature for another 30 min, then at 25 °C for 1 h, and then at 50°C for 1 h. As soon as the epoxidation is over, m- chloroperoxybenzoic acid residues are neutralized with a sodium hydroxide solution, and the reaction mass is washed with three-fold volumetric excess of water followed by separation of the aqueous layer and the organic layer.

The organic layer comprising the partially epoxydized styrene-butadiene copolymer is loaded into a flask. Stirring begins, and the bath temperature is set to 35°C. A solution of 0.4 g of diethylamine in 1 g of dichloromethane is dosed into the flask for 1 minute, an organic catalyst solution (3.16 g of dibutyltin dilaurate and 10 g of dichloromethane) is added in 15 minutes, the temperature is raised to 38°C, and stirring continues for 6 hours. Then the reaction mass is washed with three-fold volumetric excess of water followed by separation of the aqueous layer and the organic layer.

The organic layer comprising the partially epoxidized and aminated styrene- butadiene copolymer is loaded into a dark glass flask, stirring begins, and the bath temperature is set to 35°C. 12 g of butanol, 2 g of water, a solution of bromine in dichloromethane (7.5 g of bromine per 7.5 ml of dichloromethane) is dosed for 5-20 min. Upon the addition of the whole solution of bromine in dichloromethane, stirring continues for 30 min, then a 10% solution of sodium thiosulfate is added, and bromine is neutralized for 60 min. After that, the aqueous layer is poured out, while the organic layer comprising a modified styrene-butadiene copolymer is washed with three-fold volumetric excess of distilled water. Then the modified styrene-butadiene copolymer comprising epoxide groups, hydroxyl groups, amino groups, and bromine atoms is precipitated in five-fold excess of an alcohol, separated and dried by distilling the solvent at 91°C and 10 kPa, followed by additional drying in a vacuum drying oven at 70°C and 0.5 kPa.

Characteristics of the product obtained according to Example 1 are set out in Table 1.

The 'H NMR spectrum of the produced modified styrene-butadiene copolymer is shown in Fig. 2.

The 'H NMR spectrum (CDCb, d, ppm): 6.3-7.2 (styrene); 5.2-5.7 (1,4- butadiene); 4.9-5.05 (1,2-butadiene); 4.05^4.2 (amino groups); 2.8-3.0 (epoxide groups).

Example 2 (comparative). Production of a hydroxybrominated copolymer

(according to RU2530021)

A solution of the starting styrene-butadiene copolymer (20 g in 200 g of dichloromethane) is cooled under stirring to 0-5°C. A solution of 0.083 g of 77% m- chloroperoxybenzoic acid in dichloromethane (1 mol of the acid per 1 mol of epoxidized diene units) is dosed to the cooled copolymer solution. The temperature of the cooling bath is maintained at 0-5°C. After the whole volume of the acid has been added, the reaction mass is stirred at the predetermined temperature for another 30 min, then at 25 °C for 1 h, and then at 50°C for 1 h. As soon as the epoxidation is over, m- chloroperoxybenzoic acid residues are neutralized with a sodium hydroxide solution, and the reaction mass is washed with three-fold volumetric excess of water followed by separation of the aqueous layer and the organic layer.

The organic layer comprising the epoxidized styrene-butadiene copolymer is placed in a dark glass flask, into which 60 g of butanol and 5 g of water are further added, and a solution of bromine in dichloromethane (39.4 g of bromine per 50 ml of dichloromethane) is dosed for 10-20 min. After the whole solution of bromine in dichloromethane has been added, stirring continues for 30 min, then a 10% solution of sodium thiosulfate is added, and bromine is neutralized for 60 min. After that, the aqueous layer is poured out, while the organic layer is washed with three-fold volumetric excess of distilled water. Then the resultant hydroxybrominated styrene- butadiene copolymer is precipitated in five-fold excess of an alcohol, separated and dried by distilling the solvent at 91°C and 10 kPa, followed by additional drying in a vacuum drying oven at 70°C and 0.5 kPa.

Characteristics of the product obtained according to Example 2 are set out in Table 1.

Example 3 (comparative). Production of an epoxybrominated copolymer

(according to RU2530021)

A solution of the starting styrene-butadiene copolymer (10 g in 100 g of dichloromethane) is cooled under stirring to 0-5°C. A solution of 1.32 g of 77% m- chloroperoxybenzoic acid in dichloromethane (1 mol of peroxide per 1 mol of epoxidized diene units) is dosed to the cooled copolymer solution. The temperature of the cooling bath is maintained at 0-5°C. After the whole volume of the acid has been added, the reaction mass is stirred at the predetermined temperature for another 30 min, then at 25 °C for 1 h, and then at 50°C for 1 h. As soon as the epoxidation is over, m- chloroperoxybenzoic acid residues are neutralized with a sodium hydroxide solution, and the reaction mass is washed with three-fold volumetric excess of water followed by separation of the aqueous layer and the organic layer. The water and the solvent are distilled from the epoxidized styrene-butadiene copolymer at 91°C and 9 kPa, followed by drying the same in a vacuum drying oven at 91°C and 1 kPa.

Thereafter, the organic layer comprising the epoxidized styrene-butadiene copolymer is placed in a dark glass flask, into which a solution of tetrabutylammonium in dichloromethane (36.13 g of tetrabutylammonium per 20 ml of dichloromethane) is added, and a solution of bromine in dichloromethane (17.9 g of bromine per 20 ml of dichloromethane) is dosed for 10-20 min. After the whole solution of bromine in dichloromethane has been added, stirring continues for 30 min, then a 10% solution of sodium thiosulfate is added, and bromine is neutralized for 60 min. The aqueous layer is then poured out, while the organic layer comprising the epoxybrominated styrene- butadiene copolymer is washed with three-fold volumetric excess of distilled water. The resultant modified styrene-butadiene copolymer comprising epoxide groups and bromine atoms is precipitated in five-fold excess of an alcohol, isolated and dried by distilling the solvent at 91°C and 10 kPa, followed by additional drying in a vacuum drying oven at 70°C and 0.5 kPa.

Characteristics of the product obtained according to Example 3 are set out in Table 1.

Example 4. Production of a hydroxyepoxybrominated copolymer

A solution of the starting styrene-butadiene copolymer in dichloromethane (10 g of the copolymer per 150 g of dichloromethane) is placed into a 250 ml dark glass flask. 30 g of butanol, 7.6 g of water is further added to the flask, after which a solution of 17.74 g of bromine in 20 ml of dichloromethane is dosed. The modification reaction is allowed to run for 30-40 min. As soon as the reaction is over, a solution of sodium hydroxide (NaOH) is added to the flask, and the neutralization is carried out for 1 hour. Then the reaction mass comprising the modified styrene-butadiene copolymer is washed with three-fold volumetric excess of water.

The resultant modified styrene-butadiene copolymer is filtered and precipitated in iso-propanol, then dried by distilling the solvent at a temperature of 30-95°C and at a pressure of 3 kPa, followed by further drying in a vacuum drying oven at 70°C and 0.5 kPa.

Characteristics of the modified styrene-butadiene copolymer obtained according to Example 4 are set out in Table 1.

Table 1. Comparative table of results of the experimental production of modified diene-containing (co)polymers

3°

Example 5. Production of expandable polystyrene

87 parts of water, 0.43 parts of a polymerization stabilizer (a mixture of sodium pyrophosphate and magnesium sulfate) are mixed in a flask at a temperature of 25°C. A mixture of 100 parts of styrene, 0.46 parts of a mixture of polymerization initiators (benzoylperoxide and tert-butylperbenzoate), 0.62 parts of a flame retardant on the basis of the modified styrene-butadiene copolymer produced according to Examples 1-4, and 0.21 parts of a flame retardant synergist, dicumyl peroxide, is added to said mixture under stirring. The mixture is stirred for 2 hours at a temperature of up to 85°C, then heated to 115°C for 4.5 hours. 70 min after the temperature in the flask has reached 80°C, a 10% aqueous solution of polyvinylpyrrolidone is introduced into the reaction mixture. Upon additional 100-120 min, a step of expanding polystyrene is performed, in which a solution of 0.10 parts of a chain transfer agent in 4.7 parts of an expanding reactant (n-heptane) is added to the reaction mass. When 115°C have been reached, the constant temperature is maintained in the flask for 3 hours, after which the mixture is cooled to 25°C for 3 hours.

Particle-size distribution of the polystyrene obtained prior to the expanding step is determined. Results of determination of the particle-size distribution are set out in Table 2.

Table 2. Particle-size distribution of polystyrene comprising a flame retardant in compliance with technical requirements TT 2214-019-53505711-2010

The data shown in Table 1 demonstrate that the copolymer containing amino groups together with epoxide groups, hydroxyl groups, and bromine atoms in its structure (Example 1) exhibits better thermal stability (236°C) in comparison with copolymers comprising only epoxide and/or hydroxyl groups, and bromine atoms in their structure (Examples 2-4).

It can be observed on the basis of the data given in Table 2 that addition of the copolymer according to Example 1 to polystyrene generates a stable suspension, and polystyrene granules of the required dimensions, which fully meet the requirements of TT 2214-019-53505711-2010 (Table 2), form; yield of the target fractions is 93.2%.