DD156600A5 - PROCESS FOR PREPARING LIQUID POLYMERES WITH REACTIVE END GROUPS - Google Patents

Abstract

The invention relates to a process for the preparation of liquid Dienhomo- or copolymers by free-radical emulsion polymerization using regulator mixtures. The polymerization takes place with free-radical initiators and suitable emulsifiers at temperatures between 60 and 80 degrees C. By targeted variation of the concentrations of the components of the regulator mixture number average relative molecular weights between 2000 and 10,000 g / mol can be adjusted. The average functions are> equal 2.The advantage of the inventg. is that when using mixtures of regulators, the polymerizations can be led to up to 90% conversion, without a significant broadening of the molecular weight and Funktionalitaetsverteilung occurs and thus a reduction in product properties occurs.

Description

Title of the invention

Process for the preparation of liquid polymers with reactive end groups

Use of the invention

The invention relates to a process for the preparation of liquid homopolymers and copolymers having reactive end groups by free radical emulsion polymerization of dienes, the molecular mass. And the distribution of punctuations remaining unchanged through the use of regulator combinations up to high conversions.

Characteristic of the known n technical solutions

For the preparation of liquid homopolymers and copolymers with reactive end groups based on dienes by free-radical emulsion polymerization, it is necessary to use suitable transfer substances which are responsible both for setting the low molecular weights and for introducing the functional groups. When using Dialkylxanthogendisulfiden or Diaminodiphenyldisulfiden (US-PS 3580830, US-PS 3449301, DD-PS 134230, DD-PS 134444) as a transformer whose apparent transfer constant c ^> 1, decreases depending on the size of these constants with increasing Turnover the regulator / monomer ratio. At high conversions, Bas leads to an increase in the IVlol masses and to a broadening of the molar mass and point oxide distribution, which in turn leads to a reduction in the strength or other physicomechanical parameters of the networks which follow in the subsequent

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the chain elongation and crosslinking reaction are formed.

Object of the invention

The aim of the invention is to produce liquid Dienpolyniere with reactive end groups at high conversions, without a significant broadening of the functionality and molecular weight distribution occurs, which would lead to a reduction in physio-mechanical parameters of the networks. ν

Explanation of the essence of the invention

The invention has for its object to develop a process for the preparation of liquid polymers with reactive end groups based on diene homopolymers or copolymers whose Punktionalitäts- and molecular weight distribution at conversions over 40%, preferably 40 - 90 % _t remain constant.

This object is achieved in that conjugated dienes, preferably butadiene, optionally with the comonomers acrylonitrile or styrene, with free-radical initiators (eg 2,2-azo-bis-isobutyronitrile, azo-biscyanoalkansäuren, K ₂ SpOo), suitable emulsifiers, ( eg

Tallharzsäure, alkyl sulfonates) and a mixture of Dialkylxanthoge.ndisulfiden as molecular weight regulator, wherein at least one component of this mixture must have an apparent transfer constant close to 1, are polymerized by free radical emulsion polymerization between 60 and 80 ⁰ C.

When using regulator mixtures, with appropriate selection of the concentrations of the components, it is possible to set any desired apparent gross transmission constant of the mixture which is within the range of the apparent transmission constants of the components of the mixture if the ratio of the apparent transmission constants is the single regulator ^ 3. This is one

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good variation of the number average relative molecular weights of the disfiguring polymers in the range between 2000 and 10,000 g / mol possible. When replacing a certain amount of a regulator with an apparent transfer constant> 1 by a regulator with an apparent transfer constant

<1, the molecular-weight effect on sales can be extended up to 90%. The result is soluble polymers whose inconsistency is lower than when using only one regulator.

Polymerization is possible up to high conversions without deteriorating the product properties (liquid polymers, average functionality> 2, high strength of the networks).

Ü execute hru ngsbeispiele Example 1:

The liquid end-functionalized polybutadiene is prepared in the following manner:

In a premixer 16 parts Tallharzsäure (K-SaIz) in 785 parts dest. Dissolved water with gentle warming and cooled the solution. Thereafter, 6.15 parts of 4,4'-azo-bis-4-cyanopentanoic acid are added and the pH is adjusted to 10.2 - 10.4 with KOH. The regulator or the regulator mixture (regulator concentration: Monomerkonze.ntratio.n = 0.016) is introduced into the reaction vessel and the solution prepared in the premixer is added. After repeated evacuation and purging with inert gas 200 parts of butadiene are added and the emulsion for 30 min. stirred at room temperature. The polymerization is carried out at 70 ⁰ C under the control of the reaction pressure and the MoηoinerUmsatzes. At the desired monomer conversion, the polymerization is stopped and the polymer in 5-fold.n excess, precipitated on methanol. The polymer is once reprecipitated from methylene chloride in methanol, stabilized and dried in vacuo at 50 ⁰ G. The number-average reactive molecular weight is determined by vapor pressure osmosis in benzene, the wood mass distribution is determined by GPC in

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Tetrahydrofuran and the content of functional groups determined by sulfur analysis.

When using a controller with an apparent transfer constant of 8.4, the following values were obtained:

Table 1:

Sales M

12.3 1590 24.5 2320 55.8 3380 84.8 4540

2.8 2.14 2.17 2.22

The broadening of the molecular weight distribution is shown in Fig. 1.

Example 2;

If certain components of the controller from example 1 are replaced by a controller with an apparent transmission constant of 0.9, the following results:

Mol% of the regulator with c ' _u = 8.4 conversion /% / M f 30 %

40%

70 %

22.5 3150 2.26 41.5 46öO 2.15 15.5 2680 2.15 37.7 3550 1,7.2 52.5 4100 1.88 16.9 1940 2.43 34.0 2670 2.36 81.0 4200 2.36

Fig. 2 shows that the molecular weight distributions for those with the

Controller geraischen produced products at comparable monomer conversions lower than when using only the regulator with the apparent transfer constant of 8.4.

Fig. 3 shows the example of the regulator mixture with 30 Mo1% of the regulator with the apparent transfer constant of 8.4 ₅ that increasing the monomer conversion from 55 to 85 % causes no significant broadening of the molecular weight distribution of the samples.

For a regulator mixture of 0.5 Mo1% of a regulator with an apparent transmission constant of 8.4 and 0.5 Mo1% of a controller with an apparent transmission constant of 3.9, a gross transmission constant of 5.8 could be determined. This gross constant can be varied by varying the concentration ratios of the components of the regulator mixture in the specified range.

Claims (2)

7 85 36 Claim for performance 1. A process for the production of liquid polymers having reactive end groups by free-radical emulsion polymerization of conjugated dienes, preferably butadiene, optionally marked with comonomers, preferably acrylonitrile and styrene, in the presence of initiators, emulsifiers and molecular weight regulators, at temperatures between 60 and 80 ⁰ C, 'characterized, that, as a regulator , A mixture of dialkylxanthogen disulphides is used in which "at least one component has an apparent transfer constant te near 1 and the ratio of the apparent transfer constants of the individual regulators in the mixture is £ 3. 2. Method according to item 1, characterized in that in the regulator mixture a part of a regulator with the apparent transfer constant> 1 is replaced by a controller with the apparent transfer constant -c 1.