CS237289B1 - Processing of polymere diene with ending functional groups - Google Patents

Description

The invention relates to a process for preparing a polymer. . end-functional dienes, preferably of low to medium molecular weight, by anionic polymerization of conjugated dienes, in particular butadiene-1,3 or isopropyl, or copolymers of these dienes with vinylaromatic monomers, especially styrene, alpha-ethylstyronee or divinybenzene in aliphatic polymers, in aliphatic aliphatic polymers; , cycloaliphatic or aromatic hydrocarbon solvents using lithium initiators followed by functionalization of the living polymers with electrophilic agents, in particular. alkylene oxides, carbon dioxide, or gae-butyrol ^: ton ·

It is known from NSR-DOS 24 08 696 that it is possible to prepare from conjugated dienes by anionic polymerization by means of trilttis organic initiators star-like polymers optionally with terminal functional groups.

According to this procedure, the initiators of the organolithium compound obtained by the reaction of a divinylaromatic compound, e.g. diisopropyl benzene or divinylbenzene with an organometallic compound, e.g. ¹ butyllithlee, to form the eonoaduct followed by reaction of the eonoaduct, which still has free vinyl groups with the trglnotilithium compound to form the trganotrilithio compound

It is again disclosed in German-German Patent Nos. 24 27 955 and 25 21 200 that in the reaction of divinylbenzene with alkyllithium compounds under these e. sieving of the free vioyl group, O-cgel or msacrogel crosslinked products are formed which are not suitable as initiators for the preparation of low-molecular polymers.

- 3 237 289

When using diisopropylbenzene there is no danger of sulphurization, or? is substantially less reactive than divinylbenzene. However, diisopropylbenzene is out of the question for technical use because of the difficulty of its synthesis.

Such polymers, however, are desirable for the preparation of crosslinked products with high mesh density and good physical-mechanical properties. These disadvantages are eliminated by the process of preparing polymers of di-functionalized end-groups, preferably low to medium molecular weight, by anionic polymerization of conjugated dienes, especially butadiene-1,3 or copolymers of these dienes with vinylaromatic monomers, in particular styrene, alpha-methylstyrene or divinylbenzene, on living polymers, in aliphatic, cycloaliphatic or aromatic hydrocarbon solvents by means of lithium initiators, followed by; functionalization of living polymers with electrophilic agents, in particular alkyl oxides, with carbon dioxide or gamma-butyrolactone, according to the invention, characterized in that the polymerization is carried out in the presence of a suspension of defined mixtures of hexalithium and trilithium organic initiators prepared by o-, m- or % of p-divinylbenzene, a mixture thereof or a technical mixture of divinylbenzenes, consisting of 10 to 70 wt. % of divinylbenzenes, 80 to 30 wt. 10% diethylbenzene, with a trilithium compound, in particular a reaction product of a divinylbenzene and an alkylmonolithium compound, especially a secondary butyllithium, in a molar ratio of 2: 3 in an aliphatic or aromatic hydrocarbon, preferably in benzene or toluene, at a mole ratio of vinyl groups in aromatics to the trilithium compound 1: 2 to 1: 10, wherein the polymerization is carried out at a temperature of 198 to 423 K _e

The process can preferably be carried out at a polymerization temperature of 273 to 323 K.

237 289

It is an advantage of the process according to the invention that low to medium molecular weight polymers and copolymers can be obtained which, when reacted with suitable electrophilic agents, give polymers having a mean functionality of 3 to 4.5 and have a low molecular weight dispersion.

These initiators are insoluble in the reaction medium and added as a suspension in the corresponding solvent. They are linear, non-crosslinked low molecular weight organolithium compounds having an average molecular weight of less than 500 and are therefore particularly suitable for the synthesis of low molecular weight polymers. ’

Suitable reaction media are aliphatic, cycloaliphatic and aromatic hydrocarbons such as n-hexane, n-heptane, gasoline fraction, cyclohexane, benzene or toluene. The polymerization can be carried out at a temperature of from 198 to 423 K, preferably at 273 to 323 K at atmospheric or elevated pressure. Other conditions are common as with other anionic polymerizations reaction times are generally 1 to 3 hours.

The amount of initiators is determined by the desired molecular weight since it is a stoichiometric polymerization. The initiators are converted into a soluble form by means of polymerizable monomers so that the polymer solution is homogeneous during the polymerization. It is surprising that there is no wide dispersion of molecular weights. The molecular weight dispersion of the polymer is 1.1 to 1.4 on average.

The active chain ends of the resulting living polymers can then be functionalized in a manner known per se by functionalizing electrophilic agents such as carbon dioxide, alkylene oxides, apichlorohydrin or gamma-butyrolactone to form telechelic polymers.

No side reactions occur during the polymerization reaction, so that after functionalization of the active polymers to telechelic polymers, t achieves high functionality. The functionality of the polymers corresponds to that of the initiator. These polymers can be easily crosslinked by bifunctional crosslinking agents.

237 289

By the method of the invention, they eliminate such disadvantages of known methods as the unavailability of low molecular weight multifunctional lithium initiators, low initiator efficiency, limited molecular weight adjustment, wide molecular weight scattering and low functionality of polymer products.

The resulting polymers are blends of linear and star polymers with a low viscosity, which is lower than that of pure linear polymers, thereby rendering their processing brown. Functionalized polymers are mixtures consisting of hexafuncones and trifunctional polymer molecules. The trifunctional moiety can be controlled by the molar ratio of the trilithium compound to the vinyl groups in the initiator, while the hexafunctional moiety remains constant. The mean functionality of the polymers is 3 to 5

4.5 and is a function of this molar ratio. Such mixed-functionality polymers are of interest for the preparation of crosslinked products, and depending on the ratio of the hexafunctional and trifunctional portion of the polymer, different networks can be obtained and thus the physical-mechanical properties of the crosslinked products can be varied over a wide range.

Example 1

To a suspension of the initiator prepared by the reaction of 40 mmol of m-divinylbenzene with 160 mmol of a trilithium compound prepared from secondary butyllithium and γ-divinylbenzene in a molar ratio of 3: 2 in 200 ml of benzene was added 500 ml of benzene and then 240 g. butadiene. The polymerization temperature was 308 ° C. 0.57 moles of ethylene oxide were then added to the living polybutadiene solution at 278K and the resulting alcoholate was hydrolyzed with 100 ml of water. The aqueous phase and the lithium salts were centrifuged. After removal of the solvent from the organic phase on a vacuum rotary evaporator, liquid polybutadiene with an average molecular weight of 2700 and a functionality of 3.95 (theoretical 4 > 0) was obtained. The polymer contained 65 mole% of the structure

1.4 and 35 mole% of the 1.2 structure.

Example 2

237 2B9

Example 1 was repeated, except that an initiator of 10 ranoles of p-divinylbenzene and 200 moles of trilithium compound was used and 360 g of isoprene were polymerized. ) and scattering of molecular hmooinoai Мде / Мд * 1,2 ·

Example 3

100 g of butadiene-1,3 were polymerized by means of an initiator which was obtained from 4 g of a technical mixture of divinylbenzenes containing 60.3% by weight of divinylbenzenes (18 mm @ 3, 30.3% by weight of ethylatyrene (9 mol)). and 9.4 wt.% diethylbenzene and up to 54 moles of the trilttho compound as in Example 1. The polymerization was carried out in 400 ml of toluene at 323 K for 2 hours. 35 g of styrene were then added over 1 hour. The ethylene oxide and the polymer treated as in Example 1, the insulated butadiene styrene polymer had a molar spherical molarity of 3500 and a mean functionality of 3.9 (theoretical 4.0), consisting of 85% butadiene and 15% styrene, yield 100%.

Claims (2)

Object of the invention 237 289 Process for preparing polymers of functionalized dienes, preferably of low to medium molecular weight, by anionic polymerization of conjugated dienes, in particular butadiene -1,3 or isoprene, or a copolymer of these dienes with vinylaromatic monomers, in particular styrene, alphamethylstyrene or divinylbenzene, to live polymers, in aliphatic, cycloaliphatic or aromatic hydrocarbon solvents using lithium initiators followed by functionalization of living polymers with electrophilic agents, in particular alkylene oxides, carbon dioxide or gamma-butyrolactone, characterized in that the polymerization is carried out in the presence of a suspension of defined mixtures of hexalithium and trilithium initiators prepared by the reaction of o-, m- or p-divinylbenzene, a mixture thereof or a technical mixture of divinylbenzenes, consisting of 10 to 70% by weight of divinylbenzenes, 80 to 30% by weight of ethylstyrene and about 10% of diethylbenzene, with a trilithium compound, in particular a reaction product; from a divinylbenzene and an alkylmonolithium compound, in particular a secondary butyllithium, in a molar ratio of 2: 3, in an aliphatic or aromatic hydrocarbon, preferably in benzene or toluene, with a molar ratio of vinyl groups in aromatics to trilithium compound of 1: 2 to 1: 10; polymerization is carried out at a temperature of 198 to 423 K, 2. A process according to claim 1, wherein the polymerization is carried out at 273 to 323 K.