DE1128142B - Process for the production of impact-resistant polystyrene - Google Patents

Description

It is known that impact-resistant polystyrene can be obtained by using a solution of natural rubber or polymerized from synthetic rubber in blocks, in emulsion or in suspension with styrene. However, these known processes have the disadvantage that both natural rubber and synthetic rubber are sparingly soluble in monomeric styrene. That is why one was previously forced to use these sensitive Solutions of rubbers in styrene to be filtered before polymerization, if one is not uneven Wanted to receive products.

It has also been proposed to use solutions of 1,2-polybutadiene or 3,4-polyisoprene in styrene to polymerize. The 1,2-polybutadiene and also the 3,4-polyisoprene dissolve more easily in styrene than the types of rubber previously used. Their effectiveness in terms of improving the Impact strength and the. Notched impact strength is, however, significantly lower than that of the previously used Rubbers. That is why you have to have such large amounts of 1,2-polybutadiene or 3,4-polyisoprene that other properties, such as the softening point, are intolerable be worsened.

It has been found that impact-resistant poly- ^ 5 styrene can be made more advantageously by polymerizing a solution of polybutadiene in styrene, though 1,4-cis-rich polybutadienes are used as the polybutadiene. These 1,4-cis-rich polybutadienes are by polymerizing butadiene with the aid of mixed catalysts made from cobalt dichloride and alkyl aluminum chlorides or from titanium halides, in particular titanium tetrabromide or titanium tetraiodide, and aluminum trialkyls. You should at least 80%, preferably more than 90% and in particular more than 94% of 1,4-cis-polybutadiene contain. The 1,4-cis-polybutadiene surprisingly dissolves light and clear in styrene. In particular, the solutions show no residues and, in contrast to earlier processes, do not need to be filtered before polymerization will. The 1,4-cis-rich polybutadienes are used in amounts of 2 to 20 percent by weight, preferably 4 to 10 percent by weight, based on styrene.

As a result of the lower viscosity, the solutions obtained can advantageously be polymerized not only in the block, but also in suspension or, if appropriate, in emulsion. The polymerization takes place in a manner known per se with the aid of polymerization activators, such as benzoyl, lauroyl and / or di-tert-butyl peroxide. In the suspension process of manufacture
of impact-resistant polystyrene

Applicant:

Chemical works Hüls Aktiengesellschaft, Marl (Kr.Recklinghauseri)

Dr. Erwin Heinrich, Dr. Walter Franke,

Dr. Heinrich Weber, Dr. Johannes Schäfer

and Dr. Rudolf Praefke, Marl (district of Recklinghausen),

have been named as inventors

polymerization, water-soluble organic protective colloids, such as polyvinyl alcohol, gelatin, methyl cellulose, are preferably used as dispersants or sodium polyacrylic acid, in amounts of 0.1 to 2%, preferably 0.25 to 1%. the Polymerization takes place at temperatures between 50 and 200 ° C. The individual requirements depend on the Temperatures according to the desired properties of the products and in particular according to the Decomposition temperatures of the polymerization activators used. It can be beneficial to that To change the polymerization temperature in the course of the polymerization and, for example, with a start at a lower temperature and then polymerize out at higher temperatures. as well it can be useful to change the phase ratio in the course of the polymerization by for example, you start with a smaller amount of water and then in the course of the polymerization, when the individual monomer droplets have a certain toughness and Having reached stickiness, add additional amounts of water and dispersant. Plasticizers and lubricants, for example butyl stearate, cyclohexyl stearate, dioctyl phthalate, Bone oil and soybean oil, as well as filler stone, dyes and color pigments in themselves be added in a known manner. -

Impact-resistant polystyrenes are obtained which have excellent impact strength and notched impact strength are hardly affected in their softening point, since the 1,4-cis-rich polybutadienes are already at

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small additions greatly increase the impact strength and notched impact strength.

example 1

_{21 kg of water, 66.5 g of polyvinyl alcohol, 3.3 g (20%) of alkyl sulfonate (Q 2} to Qβ), 6.7 g are added to a solution of 350 g of polybutadiene with 94 percent by weight 1,4-cis content in 6650 g of styrene Benzoyl peroxide and 6.7 g of di-tert-butyl peroxide were added. With vigorous stirring, polymerization is carried out at 50 ° C. up to a conversion of about 15%, then at 80 ° C. up to a conversion of 80% and then at 130 ° C. up to about 98% conversion. It is then held at 180 ° C. for a further hour, so that virtually no more monomeric styrene can be detected. The resulting polymer is filtered off, washed and dried at 60 ° C. in a circulating air drying cabinet. Standard bars produced therefrom show an impact strength of 91.4 cmkg / cm ² and a notched impact strength of 9.7 cmkg / cm ² . ²⁰ 'The softening point of the resulting impact polystyrene is 100 ° C compared to 102 ° C in the absence of a polybutadiene under otherwise comparable conditions obtained polystyrene.

Noteworthy is the temperature independence of the impact strength and notched impact strength, which is 87.6 and 9.0 cmkg / cm ² at 0 ° C and 86.8 and 7.6 cmkg / cm ^{2 at -20 ° C.}

Example 2

350 g of polybutadiene with 94 percent by weight 1,4-cis content are dissolved in 7500 g of styrene. The solution 9400 g of water, 75 g of bone oil, 150 g of butyl stearate are used and 12.3 g of di-tert-butyl peroxide are added, then at 110 ° C up to a conversion of 45% polymerized. Then a further 9,350 g of water, 3.75 g of alkylbenzenesulfonate and 37.5 g of polyvinyl alcohol are added added, then polymerization is continued at 140 ° C. until conversion is complete. That filtered off, washed and at 60 ° C in a circulating air drying cabinet Dried polymer is injected into standard rods and gives the following values during the test:

Impact strength 63.8 cmkg / cm ²

Notched impact strength 9.5 cmkg / cm ²

Claims (1)

PATENT CLAIM: Process for the production of impact-resistant polystyrene by polymerizing a solution of polybutadiene in styrene, characterized in that the polybutadiene used is a 1,4-cis-rich polybutadiene. Legacy Patents Considered:
German Patent No. 1 104 702. © 209 560/531 4.62