CS237290B1 - Processing of polymere diene with ending functional groups - Google Patents

Description

BACKGROUND OF THE INVENTION The present invention relates to a process for the preparation of polymers of diene functional groups, in particular low to medium molecular weight, by anionic polymerization of conjugated dienes, in particular butadiene-1,3 or isoprene, or by copolymerization of these diols with vinyl aromatic monomers. polymers in aliphatic, cycloaliphatic or aromatic hydrocarbon solvents, by means of lithium initiators and subsequent functionalization of living polymers by electrophic agents, in particular alkylene oxides, carbon dioxide or gamabutyrolactoate.

It is known from NSR-DOS 24 08 696 that from conjugated dienes it is possible to prepare star polymers by anionic polymerization with organotrilithium initiators, optionally with terminal functional groups having a functionality of 3 ·

According to this method, organolithium compounds obtained by reaction of a divinylaromatic compound ‘e.g. diisopropylbenzene or divinylbenzene with an organomonolithium compound, for example · secondary butyllithium, to form a monoaduct followed by reaction of a monoaduct having still free vinyl groups with an organodilithium compound to form an organbtrilithium compound · On the other hand, NSR-DOS 24 27 955 and 25 It is known that the reaction of divinylbenzene with alkyllithium compounds results in such molar ratios, in which free vinyl groups occur to form microgel or macrogel crosslinked products which are not suitable for the preparation of low molecular weight polymers.

With the use of diisopropylbenzene, there is no danger of cross-linking since it is substantially less reactive than divinylbenzene. However, diisopropylbenzene is out of the question for its demanding sythesis when used on a technical scale.

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Another disadvantage of this process is that it is not possible to prepare polymers with a functionality above 3 ·

However, such polymers are desirable for the preparation of crosslinked products with high mesh density and good mechanical properties.

These disadvantages are overcome by a process for the preparation of end-functional diene polymers, in particular low to medium molecular weight, by anionic polymerization of conjugated dienes, in particular butadiene-1,3 or isoprene, or by copolymerization of these dienes with vinylaromatic monomers, especially styrene, alfamethylstyrene or divinylbenzene. polymers in aliphatic, cycloaliphatic or aromatic hydrocarbon solvents with lithium initiators and subsequent functionalization of living polymers with electrophilic agents, in particular alkylene oxides, carbon dioxide or garnabutyrolactone according to the invention, characterized in that the polymerization is carried out at 19Θ to 423 K in the presence of hexalithium suspension initiators prepared by the reaction of o-, m- or p-divinylbenzenes or mixtures thereof with a hydrocarbon solution of an organotrilithium compound, in particular with the reaction product of divinylbenzene with an alkyl mono preferably a lithium compound with a secondary butyllithium in a molar ratio of 2: 3, in an aliphatic or aromatic hydrocarbon, especially benzenes or toluene, with a molar ratio of divinylbenzene to trilithium compound of 1: 2.

An advantage of the process according to the invention is that it allows the synthesis of living polymers and copolymers of low to medium molecular weight, which, when reacted with suitable electrophilic reagents with end-functional groups, give functionality close to 6. The polymers have a narrow molecular weight distribution. Other disadvantages of the known methods are also eliminated.

237 290

The initiators according to the invention are insoluble in the reaction medium and are used in the form of a suspension in the corresponding solvent. Is a linear, non-crosslinked low molecular weight organolithium compounds, and ^e f average molecular hmotnnoSí less than 500, and are particularly suitable Tudie Dec. nízkomooekuuárních.polymerů synthesis.

In addition to the above, all other anionic polymerizable monomers can be used as comonomers in the synthesis.

The polymerization is carried out under conventional conditions for anionic solution polymerization by alkali metal initiators. Suitable reaction media are aliphatic, cycloaliphatic and aromatic hydrocarbons such as n-hexane, n-heptane, gasoline fraction, cyclohexane, benzene or toluene. The polymerization is carried out at temperatures of 198 and 423 K, preferably at 273 and 323 K, at atmospheric or elevated pressure. The polymerization time is generally 1 to 3 hours.

Used. The amount of initiator depends on the desired molecular weight, since it is a stoichiometric polymerization. The initiators are converted by means of a polyerizable polymer into a solubilized form such that the polymer solution during the polymerization is homo. Surprisingly, they arise. . polymers. with a narrow distribution of monococcus. is on average for polymeS

1.1 to 1.4 Ц?%) ·

During polymerization. reaction. the side reactions are not impaired, so that high-performance polymers with high functionality are obtained. corresponds to funkcconnaite. These polymers can be cured simply by bifunctional crosslinking agents. Resulting. the polymers are star-shaped and have a lower viscosity than the non-linear polymers, which facilitates them. treatment.

Example 1

To a suspension of 30 mm ml of hexalithium initiator prepared by the reaction of 30 moles of ε-p-divinylbenzene with 90 µl of a trilithium compound which was the reaction product of secondary lithium with p-dibenzobenzene in a 3: 3 ratio. . 2

237 290 and 600 ml of benzene were added under argon and then 135 g of butadiene-1.3 were gradually added over a period of 2 hours. The polymerization temperature was 298 K. After polymerization, 216 mmol of ethylene oxide were functionalized at 278 K and hydrolyzed with water. After removal of the solvent, the isolated polybutadiene had an average molecular weight, as determined by vapor phase osmosis, of 3700 (3715 theoretical). The hydroxyl content was 2.67 wt. %, resulting in a functionality of 5.8. The fraction of structure 1.4 was 69 mol%, structure-1.2 31 mol% ·

Example 2

Using 40 mmol of a hexalithium compound prepared from pdivinylbenzene and a trilithium compound prepared from secondary butyllithium and m-divinylbenzene in a molar ratio of 3: 2, suspended in 800 ml of benzene, were polymerized at 273 K to 240 g of isoprene over 2 h. The living polymer was functionalized with gaseous carbon dioxide. The resulting solid carboxilate was converted to polyisoprene hexacarboxylic acid with hydrogen chloride gas. Excess hydrogen chloride was neutralized with sodium carbonate and the alkali metal salts were filtered off. After removal of the solvent, a 100% yield of liquid polyisoprene with carboxyl end groups was obtained having an average molecular weight M _{n of} 4800 (theoretical 4715). resulting in a functionality of 5.9

1.15.

Example 3

200 mmol of hexalithium initiator, prepared from 20 mmol of m-divinylbenzene and 60 mmol of trilithium compound, prepared from secondary butyllithium and m-divinylbenzene in a molar ratio of 3: 2, in benzene and 600 ml of toluene were placed under argon in a sulfonation atmosphere. banks. To this suspension was added 600 g butadiene over a period of 1.5 h and then 40 g

237 290 styrene. After the last styrene charge, the mixture was stirred for a further 0.5 h and then carboxylation and further processing as in Example 2 were carried out.

The yield was 100%. The resulting 35 block butadiene styrene copolymer had an average molecular weight of 4200 and a functionality of 5.98.

The proportion of butadiene in the block copolymer was 74.5 mol% and the proportion of styrene was 25.5 mol%.

Claims (2)

Object of the invention 237 290 I. Process for preparing polymers of diene functional groups, in particular low to medium molecular weight, by anionic polymerization of conjugated dienes, in particular butadiene-1,3 ndbo isoprene, or copolymerization of these dienes with vinylaromatic monomers, in particular styrene, alfamethylstyrene or divinylbenzene, into living polymers , in aliphatic, cycloaliphatic or aromatic hydrocarbon solvents, by means of lithium initiators and subsequent functionalization of living polymers with electrophilic agents, in particular alkylene oxides, carbon dioxide or gamabutyrolactone, characterized in that the polymerization is carried out at a temperature of 198 K to 423 K, a suspension of hexalithium initiators, prepared by reacting o-, m- or p-divinylbenzene or a mixture thereof, with a hydrocarbon solution of an organotrilithium compound, in particular with a reaction product of divinylbenzene with an alkylmonolithium compound, preferably with a secondary b utyllithium, in a molar ratio of 2: 3 »in an aliphatic or aromatic hydrocarbon, in particular benzene or toluene, with a molar ratio of divinylbenzene to trilithium compound of 1: 2 · Process according to claim 1, characterized in that the polymerization is carried out at 273 K to 323 K.