Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
METHOD FOR THE PREPARATION OF HYDROXYLATED POLYOLEFINS
Document Type and Number:
WIPO Patent Application WO/2017/097702
Kind Code:
A1
Abstract:
The invention relates to a process for the preparation of hydroxylated polyolefins by living anionic polymerization of olefin monomers and subsequent functionalization with hydroxyl groups. With the inventive method, a high degree of functionalization can be achieved.

Inventors:
COUET, Julien (Heimstättenweg 84, Darmstadt, 64295, DE)
SCHWARZ, Markus (Bergstraße 6A, Haltern am See, 45721, DE)
STERZEL, Walter (Grießheimerstr. 12, Marl, 45770, DE)
Application Number:
EP2016/079746
Publication Date:
June 15, 2017
Filing Date:
December 05, 2016
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
EVONIK OIL ADDITIVES GMBH (Kirschenallee, Darmstadt, 64293, DE)
International Classes:
C08F2/00; C08F2/06; C08F2/12; C08F2/38; C08F136/06; C08L9/00
Domestic Patent References:
WO2014075901A12014-05-22
Foreign References:
US20040236167A12004-11-25
Download PDF:
Claims:
CLAIMS

A method for the preparation of a hydroxylated polyolefin by living anionic polymerization comprising the steps of:

a) providing a reaction mixture comprising:

a diene,

a polar solvent which is an aprotic solvent comprising at least one oxygen, sulfur or nitrogen atom,

a non-polar solvent, which is a hydrocarbon solvent, and

an anionic initiator;

b) allowing the reaction mixture to polymerize; and

c) terminating the polymerization by addition of an epoxide;

characterized in that

the polymerization is carried out at a temperature of 50°C or less,

the molar ratio of polar solvent to anionic initiator is 3 or less, and

the amount of diene in the reaction mixture is 40 wt-% or less, based on the total weight of the reaction mixture,

wherein the diene is selected from the group consisting of 1 ,3-butadiene, 1 ,3-pentadiene, 2,3- dimethylbutadiene, phenylbutadiene, isoprene, or mixtures thereof.

The method according to claim 1 , further comprising hydrogenating the hydroxylated polyolefin.

The method according to claim 1 , characterized in that the diene is 1 ,3-butadiene.

The method according to any one of claims 1 to 3, characterized in that the polar solvent is selected from the group consisting of diethyl ether, dimethyl ether, tetrahydrofuran, 3-methyl- tetrahydrofuran, ethyl acetate, acetone, dimethylformamide, acetonitrile, dimethyl sulfoxide, nitromethane, propylene carbonate, tetramethylethylenediamine,

pentamethyldiethylenetriamine, hexamethylphosphortriamide, and mixtures thereof.

The method according to any one of claims 1 to 4, characterized in that the non-polar solvent is selected from hydrocarbons with 5 to 10 carbon atoms, and mixtures thereof.

The method according to any one of claims 1 to 5, characterized in that the anionic initiator is an alkyllithium.

The method according to any one of claims 1 to 6, characterized in that the epoxide is an alkylene oxide with 2 to 10 carbon atom, or a mixture thereof. The method according to any one of claims 1 to 7, characterized in that the polymerization is carried out at a pressure in the range of 1 to 100 bar.

The method according to any one of claims 1 to 8, characterized in that the polymerization is carried out at a temperature in the range of 10°C to 50°C.

The method according to any one of claims 1 to 9, characterized in that the molar ratio of polar solvent to anionic initiator is in the range of 0.5 to 3. 1 1. The method according to any one of claims 1 to 10, characterized in that the amount of diene in the reaction mixture is in the range of 5 to 40 wt-%, based on the total weight of the reaction mixture.

Description:
Method for the preparation of hydroxylated polyolefins The invention relates to a process for the preparation of hydroxylated polyolefins by living anionic polymerization of olefin monomers and subsequent functionalization with hydroxyl groups. With the inventive method, a high degree of functionalization can be achieved.

Living anionic polymerizations is a well-known method for the polymerization of vinyl group containing monomers using anionic initiators [Baskaran, D. and Miiller, A. H. E. (2009) Anionic Vinyl

Polymerization, in Controlled and Living Polymerizations: From Mechanisms to Applications (eds A. H. E. Muller and K. Matyjaszewski), Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany]. The term living refers to the fact that the polymerization generates polymer chains with stable carbanionic chain ends that retain their reactivity for a sufficient amount of time, thus enabling continued propagation without termination and transfer reactions. Because of the absence of termination and transfer reactions, each initiator molecule produces one living polymer chain. If the initiator is sufficiently reactive, the rate of initiation will be faster than the rate of chain propagation, and as a consequence, polymers with a narrow molecular weight distribution can be obtained. Due to the stability of the carbanionic chain and, the polymer chains can be functionalized with a diverse array of functional end groups by reaction with a variety of electrophilic reagents. Living anionic polymerization thus allows for the synthesis of well-defined, chain-end functionalized polymers with low degrees of compositional heterogeneity.

The synthesis of polybutadiene by living anionic polymerization of 1 ,3-butadiene using n-butyllithium as initiator is, for example, described in WO 2014/075901 A1. By reaction of the carbanionic polybutadiene chain end with an epoxide such as propylene oxide, the polymer can be functionalized with a single hydroxyl group, yielding a mono-hydroxylated polybutadiene, which is of particular industrial importance. For some applications, the resulting mono hydroxylated polybutadiene can further be hydrogenated to produce a fully saturated, long chain monoalcohol. A process for the preparation of a fully saturated monohydroxy-polybutadiene is, for example, described in WO

2015/040095 A1.

One difficulty of this manufacturing process is to maximize the yield of functionalized polymer.

Electrophilic reactants other than the epoxide group, such as for example acidic protons on the methyl substituent of propylene oxide, may react with the strongly basic carbanion of the living polymer chain to produce non-functionalized polymer ends (Quirk, R. P., & Gomochak, D. L. (2003). Recent advances in anionic synthesis of chain-end functionalized elastomers using epoxides and related compounds, Rubber chemistry and technology, 76(4), 812-831 ). This results in a reduction of the yield of functionalized polymer. Little attention has been paid to this problem in the prior art. In particular, known methods rarely reach high functionalization values of 95% or higher. The present invention, therefore, aims to provide a method for the preparation of hydroxylated polyolefins with a high degree of hydroxyl-functionalization, preferably a degree of functional ization of more than 98%, even more preferably more than 99%. Here, the degree of functional ization refers to the number of polymer chains bearing a hydroxyl group relative to the total number of polymer chains.

To solve this problem, the present invention has found that the degree of functionalization of polyolefins can be controlled by the polymerization temperature, the molar ratio of polar solvent to anionic initiator, and the amount of olefin in the reaction mixture.

The present invention, therefore, relates to a method for the preparation of a hydroxylated polyolefin by living anionic polymerization comprising the steps of:

a) providing a reaction mixture comprising:

an olefin,

a polar solvent, which is an aprotic solvent comprising at least one oxygen, sulfur or nitrogen atom,

a non-polar solvent, which is a hydrocarbon solvent, and

an anionic initiator;

b) allowing the reaction mixture to polymerize; and

c) terminating the polymerization by addition of an epoxide;

characterized in that

the polymerization is carried out at a temperature of 50°C or less,

the molar ratio of polar solvent to anionic initiator is 3 or less, and

the amount of olefin in the reaction mixture is 40 wt-% or less, based on the total weight of the reaction mixture.

In some embodiments, the method may further comprise a step of hydrogenating the hydroxylated polyolefin. In some embodiments, the olefin may be selected from the group consisting of styrenes, dienes, acrylates, acrylamides, acrylonitriles, or mixtures thereof.

In some embodiments, the reaction mixture may comprise 10 to 100 wt-% dienes, relative to the total amount of olefin.

In some embodiments, the dienes may be selected from compounds according to formula VI

CR R 2 =CR 3 -CR 4 =CR 5 R 6 (VI)

wherein R , R 2 , R 3 , R 4 , R 5 , and R 6 independently represent H, alkyl, cycloalkyl, or aryl. In some embodiments, the polar solvent may be selected from the group consisting of diethyl ether, dimethyl ether, tetrahydrofuran, 3-methyl-tetrahydrofuran, ethyl acetate, acetone, dimethylformamide, acetonitrile, dimethyl sulfoxide, nitromethane, propylene carbonate, tetramethylethylenediamine, pentamethyldiethylenetriamine, hexamethylphosphortriamide, and mixtures thereof.

In some embodiments, the non-polar solvent may be selected from hydrocarbons with 5 to 10 carbon atoms, and mixtures thereof.

In some embodiments, the anionic initiator may be an alkyllithium.

In some embodiments, the epoxide may be an alkylene oxide with 2 to 10 carbon atom, or a mixture thereof.

In some embodiments, the polymerization may be carried out at a pressure in the range of 1 to 100 bar.

In some embodiments, the polymerization may be carried out at a temperature in the range of 10°C to 50°C. In some embodiments, the molar ratio of polar solvent to anionic initiator may be in the range of 0.5 to 3.

In some embodiments, the amount of olefin in the reaction mixture is in the range of 5 to 40 wt-%, based on the total weight of the reaction mixture.

By setting the polymerization temperature, the molar ratio of polar solvent to anionic initiator, and the amount of olefin in the reaction mixture within the specified ranges, a degree of functionalization of the resulting polymer of more than 98,0%, preferably more than 99% can be achieved. In the context of the present invention, the term "polyolefin" refers to homopolymers of olefins, but also to copolymers of different olefins that can be copolymerized using living anionic polymerization.

The term "olefin" as used herein refers to any compound having a polymerisable carbon-carbon double bond. The olefin used in the inventive method is preferably substituted with an electron withdrawing group in an alpha position to the double bond.

Olefins suitable for the inventive method are, for example, styrenes, dienes, in particular conjugated dienes, acrylates, acrylamides, and acrylonitriles, all of which can be substituted with one or more alkyl, cycloalkyl or aryl groups, preferably with one or more Ci to C12 alkyl, C5 to C12 cycloalkyl, or Ce to C20 aryl groups. In a preferred embodiment, the olefin is selected from a compound according to one of the followin formulae, or mixtures thereof:

(II),

wherein each R independently represents H, alkyl, cycloalkyl, or aryl. Preferably, each R

independently represents H, Ci to C12 alkyl, C5 to C12 cycloalkyl, or Ce to C20 aryl.

The inventive method is particularly suitable for the preparation of functionalized polydienes.

Preferably, the reaction mixture therefore comprises 10 to 100 wt-% dienes relative to the total amount of olefins, preferably 50 to 100 wt-% dienes relative to the total amount of olefins, more preferably 80 to 100 wt-% dienes relative to the total amount of olefins, most preferably 95 to 100 wt-% dienes relative to the total amount of olefins.

Dienes suitable for living anion polymerization are known in the art. Substituted dienes may be used, unless they carry functional groups bearing acidic protons or other electrophiles for the reason that electrophiles react with carbanions and thus either consume the initiator or terminate polymer propagation. Dienes bearing acidic protons or other electrophilic groups may, therefore, only be used after appropriate protection of the electrophilic group.

Particularly, the inventive method relates to the polymerization of conjugated dienes. Preferably, dienes for use in the inventive method are selected from compounds according to formula (VI) CR R 2 =CR 3 -CR 4 =CR 5 R 6 (VI) wherein R , R 2 , R 3 , R 4 , R 5 , and R 6 independently represent H, alkyl, cycloalkyl, or aryl. Preferably R , R 2 , R 3 , R 4 , R 5 , and R 6 independently represent H, Ci to C12 alkyl, C5 to C12 cycloalkyl, or Ce to C20 aryl. More preferably, R 2 , R 5 , and R 6 represent H, and R , R 3 , and R 4 independently represent H, alkyl, cycloalkyl, or aryl, even more preferably H, Ci to C12 alkyl, C5 to C12 cycloalkyl, or Ce to C20 aryl. Most preferably, R , R 2 , R 4 , R 5 , and R 6 represent H, and R 3 represents H, alkyl, cycloalkyl, or aryl, even more preferably H, Ci to C12 alkyl, C5 to C12 cycloalkyl, or C6 to C20 aryl.

In a preferred embodiment, the diene is selected from the group consisting of 1 ,3-butadiene, 1 ,3- pentadiene, 2,3-dimethylbutadiene, phenylbutadiene, isoprene, or mixtures thereof. In a particularly preferred embodiment, the diene is 1 ,3-butadiene.

The inventive method is carried out in a reaction mixture comprising at least one non-polar solvent and at least one polar solvent. The weight ratio of non-polar to polar solvent in the reaction mixture may preferably be within the range of 1 to 50, more preferably 15 to 50, most preferably 30 to 45.

For the purpose of the present invention, a polar solvent is defined as a solvent having a dielectric constant (relative permittivity) of at least 4 measured at 20°C. A non-polar solvent is defined as a solvent having a dielectric constant of less than 4 at 20°C. Here, the dielectric constant of a given solvent is the ratio of the capacitance of a capacitor using that solvent as a dielectric, compared to a capacitor that has vacuum as its dielectric.

The polar solvent is an aprotic solvent, which comprises at least one oxygen, sulfur or nitrogen atom. Suitable polar solvents are, for example, diethyl ether, dimethyl ether, tetrahydrofuran, 3-methyl- tetrahydrofuran, ethyl acetate, acetone, dimethylformamide, acetonitrile, dimethyl sulfoxide, nitromethane and propylene carbonate.

In a preferred embodiment, the polar solvent is an aprotic heteroaliphatic solvent. Suitable aprotic heteroaliphatic solvents are, for example, tertiary amines, such as pentamethyldiethylenetriamine (PMDETA), and ethers, such as diethyl ether or tetrahydrofuran (THF). In a preferred embodiment, the polar solvent is selected from the group consisting of tetrahydrofuran, 3-methyl-tetrahydrofuran, dimethyl ether, diethyl ether, pentamethyldiethylenetriamine or mixtures thereof. Most preferably, the polar solvent is tetrahydrofuran. The amount of polar aprotic solvent in the reaction mixture is preferably 0.1 to 10 wt-%, more preferably 0.5 to 5 wt-%, most preferably 0.75 to 5 wt-%, based on the total weight of the reaction mixture.

The non-polar solvents are hydrocarbon solvents, such as for example, pentane, hexane, heptane, cyclopentane, cyclohexane, benzene, and toluene. The non-polar solvent is preferably a hydrocarbon having 5 to 10 carbon atoms, preferably an alkane or cycloalkane with 5 to 10 carbon atoms, more preferably hexane, heptane, cyclohexane, or mixtures thereof, and most preferably cyclohexane. The amount of non-polar solvent in the reaction mixture is preferably 40 to 90 wt-%, more preferably 30 to 85 wt-%, most preferably 50 to 80 wt-%, based on the total weight of the reaction mixture. In a preferred embodiment the polar solvent is tetrahydrofuran and the non-polar solvent is cyclohexane.

Anionic initiators suitable for the inventive method can be broadly classified into radical anions such as sodium naphtalenide, carbanions such as alkyllithiums, and oxyanions, including their thio derivatives. For example, organometallic compounds of branched or linear alkyls or aryls, which can be substituted or unsubstituted, and alkali or alkaline earth metals, preferably lithium, can be used.

Suitable initiators are, for example, sodium naphtalenide, the reaction product of an alkali metal and 1 , 1-diphenylethylene, the reaction product of an alkali metal with alpha-methylstyrene, sec- butyllithium, n-butyllithium, tert-butyllithium, fluoernyllithium, alpha-methylstyryllithium, 1 , 1- diphenylhexyllithium, diphenylmethyllithium, -sodium, or -potassium, 1 , 1-diphenyl-3- methylpentyllithium, 1 ,1 ,4,4-tetraphenyl-1 ,4-dilithium butane, and 1 ,1 ,4,4-tetraphenyl-1 ,4-disodium butane.

Alkyllithiums are preferred initiators for the inventive method, in particular in combination with tetrahydrofuran as polar solvent. A particularly preferred alkyllithium is n-butyllithium.

The epoxide added to the reaction mixture reacts with the carbanionic end of the living polymer chain to yield a polymer end functional ized with an oxyanion. To prevent a premature termination of the polymerization, the epoxide is preferably added to the reaction mixture after all dienes and other monomers have been incorporated into polymer chains. Epoxides for use in the present invention may also be referred to as alkylene oxides. Preferably, alkylene oxides with 2 to 10 carbon atoms are used. Suitable epoxides are, for example, ethylene oxide, propylene oxide, 1-butene oxide, or mixtures thereof. In preferred embodiment, ethylene oxide is used as epoxide.

To convert the oxyanion to a hydroxyl group to yield the mono-hydroxylated polydiene, the oxyanion may be reacted with a weakly acidic compound, such as an aqueous solution containing a acid, e.g. H2SO4, or an alcohol. In a preferred embodiment, a low molecular weight alcohol is added to the reaction mixture after the termination step, to convert the oxyanion to a hydroxyl group. Suitable low molecular weight alcohols are, for example, monoalcohols having 1 to 6 carbon atoms, in particular methanol.

In the case a lithium compound is used as anionic initiator, the reaction of the oxyanion with the low molecular weight alcohol yields a lithium alcoholate that precipitates from the reaction mixture and can be removed by filtration before subsequent reactions, such as hydrogenation, are carried out on the hydroxylated polydiene.

To recover the final hydroxylated polydiene, solvent may be evaporated. The inventive method is particularly suited to prepare hydroxylated, fully saturated polyolefins. To this end, the method preferably further comprises hydrogenating the hydroxylated polyolefin. A process for hydrogenating a hydroxylated polyolefin is, for example, described in WO 2015/040095 A1. The pressure, at which the polymerization is carried out, is not particularly limited. Preferably, a pressure is selected at which the diene is present as a non-supercritical liquid. In a preferred embodiment, the polymerization is carried out at a pressure in the range of 1 to 100 bar, more preferably 2 to 50 bar, most preferably 5 to 20 bar. Moreover, the polymerization is preferably carried out for a duration in the range of 30 minutes to 4 hours, more preferably 1 to 3 hours, most preferably 1 to 2 hours. In this context, the onset of polymerization is defined as the point, at which the anionic initiator is added to the reaction mixture. The end of the polymerization is defined as the point, at which the epoxide is added to terminate polymerization.

Selecting a polymerization temperature of 50°C or less is essential for the present invention, since it allows increasing the degree of functional ization to above 99%. Preferably, the polymerization temperature is in the range of 10°C to 50°C, more preferably in the range of 15 to 45°C, most preferably in the range of 25 to 40°C.

Selecting a molar ratio of polar solvent to anionic initiator of 3 or less is likewise essential to increase the degree of functional ization to above 99%. The molar ratio is calculated on the basis of the total amounts of anionic initiator and polar solvent added to the reaction. Preferably, the molar ratio is within the range of 0.5 to 3, more preferably 1 to 2, most preferably 1.25 to 1.75.

Limiting the amount of olefin in the reaction mixture to 40 wt-% or less, based on the total weight of the reaction mixture, is another essential feature for increasing the degree of functionalization to above 98,0%, preferably to more than 99%. Preferably, the amount of olefin in the reaction mixture is in the range of 5 to 40 wt-%, more preferably 10 to 35 wt-%, most preferably 15 to 30 wt-%. Here, again, the amount of olefin is based on the total weight of the reaction mixture.

In one embodiment, the reaction mixture comprises 1 ,3-butadiene, tetrahydrofuran, cyclohexane, and butyllithium, wherein the amount of 1 ,3-butadiene in the reaction mixture is 40 wt-% or less, and the molar ratio of tetrahydrofuran to butyllithium is 3 or less. In this embodiment, ethylene oxide or propylene oxide are preferably added to terminate the polymerization, preferably followed by addition of an alcohol having 1 to 6 carbon atoms, e.g. methanol, to produce the hydroxylated polydiene. Preferably, the reaction mixture in this embodiment consists of 1 ,3-butadiene, tetrahydrofuran, cyclohexane, and butyllithium.

The following examples illustrate the present invention. EXAMPLES

Molecular weights Mn and PDI of the products were determined via GPC against polystyrene standard by multiplying the resulting Mn with "Benoit factor" of 0.67 for polyisoprenes under the following conditions:

Concentration: 1.0 g/l Injection volume: 20.0 μΙ

Temperature: 40 °C Eluent: THF

Flow rate: 0.30 ml/min Column: PSS SDV 5 μηη

The amounts of 1 ,2-, 3,4- and 1 ,4-linkages were determined by ^ H-NMR with CDCI3 as an internal standard. The content of OH functionalities was determined against non-OH-functionalized standard via HPLC. Examples 1 -11. Anionic polymerization of 1 ,3-butadiene

Anionic polymerization of 1 ,3-butadiene in a mixture of cyclohexane and tetrahydrofuran in the presence of n-butyllithium (BuLi) was carried out according to the following protocol.

In a typical anionic polymerization reaction, the full amount of cyclohexane was added first into a 5 I steel reactor mechanically agitated (intermig® impeller). The solvent was then gently mixed and tetrahydrofuran (THF) was added. Next n-butyllithium (BuLi) was added to form a Li-complex with the THF (slightly exothermic reaction). The temperature within the vessel increased from 22 °C to 25 °C (pressure 1 bar). After homogenization, the valve for 1 ,3-butadiene was opened and the starting material was allowed to flow into the reactor. As soon as the monomer entered the solution, the polymerization started (very exothermic reaction). The temperature profile increased up to the desire temperature that was then maintained by activation of a water cooling system. The pressure increased to 6 bar. Butadiene dosing generally lasted 1 hour. Once the full amount of Butadiene was added the polymer solution was let to cool down to 22 °C. The functionalization was realized by the addition of propylene oxide in THF under 6 bar (slightly exothermic reaction) providing a macroalcoholate. Finally, the alcohol was gained by the addition of methanol at room temperature and under atmospheric pressure. During this last step, lithium methanolate salt was created and subsequently removed.

The OH functionality of the polymer was determined using an HPLC method using a light-scattering detector, where the tested samples were measured against a calibration curve. Several trials were carried out with varying diene concentration, THF to BuLi molar ratios, and polymerization temperature. The composition of the reaction mixture for each example are given Table 1.

The results of these trials are summarized in Table 2.

Table 1 :

CE: comparative examples (parameter values falling outside the inventive ranges are underscored) These results demonstrate that each of the three reaction conditions, i.e. diene concentration, molar ratio of THF to BuLi, and polymerization temperature may be controlled to increase the degree of functionalization. This is demonstrated for the diene concentration by comparing examples 1 and 7, for the molar ratio of THF to BuLi by comparing examples 3 and 4, and for the polymerization temperature by comparing examples 1 and 5.

However, it is clear from the results of table 2, that a degree of functionalization of 99% or more can only be achieved by a combination of a diene concentration, a molar ratio of THF to BuLi, and a polymerization temperature according to the present invention (cf. examples 8, 10, and 1 1 ).

Example 12. Anionic polymerization of isoprene

Anionic polymerization of isoprene was performed by charging a water- and oxygen-free 5 I autoclave with 2195 g cyclohexane (purified over molecular sieves), 6.2 g tetrahydrofuran (THF) and 32.3 g n- butyl lithium solution (2.0 M in cyclohexane). Under vigorous stirring at T = 40 °C and p = 3.1 bar,

402 g isoprene (purified over molecular sieves and alumina) were added at a rate of 800 g/h, yielding a final pressure of 3.9 bar. Under these conditions, the reaction mixture was stirred further for 20 min, followed by cooling of the reaction mixture to T = 20 °C and subsequent addition of 7.1 g propylene oxide in three portions at p = 1 .3 bar. The reaction mixture was stirred at T = 20 °C and p = 7.7 bar for 1 h after which 31 .4 g methanol were added at T = 20 °C and p = 1 bar. After 30 min, the mixture was filtered using 120 g Arbocell® FIC200 filtration aid, followed by evaporation of the volatile solvents.

The obtained monohydroxypolyisoprene (clear, colorless liquid) had the following properties: Mn = 4.2 kg/mol;

PDI = 1 .06;

1 ,2-content = 1 .8%;

3,4-content = 38.0%;

1 ,4-content = 60.1 %;

degree of functionalization = 99.5%.

The reaction conditions of the Example 12 are summarized in Tables 3 and 4:

Table 3

Example Cyclohexane Tetrahydrofuran Butyllithium (20% Diene

concentration in concentration in in CHX) concentration in wt-% wt-% concentration in wt-%

wt-%

12 83.3 0.2 1 .2 15.2 Table 4

Example 12 confirms that the method of the present invention also allows achieving a degree of functionalization of over 99% with substituted dienes such as isoprene.