DE1009391B - Process for the production of blowing agent-containing styrene polymers - Google Patents

Description

GERMAN

It is known, from thermoplastic polymers, the highly volatile, η i ti öse de liquids contain to produce porous masses by heating the liquid-containing polymers and the nonsolvent liquids distributed in it evaporated. For introducing the liquid propellant you can the polymers, expediently in comminuted form, with these non-dissolving liquids, optionally in the presence of small amounts of solvents, treat, or one can add the blowing agent to the monomeric compounds and the polymerization under conditions perform in which the escape of the liquid propellant is prevented. For polystyrene in this process, aliphatic or cycloaliphatic hydrocarbons are used as blowing agents suggested.

The addition of the propellant to the monomeric compounds is advantageous because this Mode of operation Polymers with a very homogeneously distributed blowing agent and, as a result, very uniform, receives fine-pored masses; but it is disadvantageous that the polymerization in the presence of the blowing agent is cumbersome and is usually very tedious. But also the introduction of the liquid propellant in the solid polymer presents difficulties because the usable blowing agent is very small Have swelling properties for the polymers in question, so that the polymer particles can be stored for a long time is required in the liquid propellants. By adding solvents for the polymers In addition to the non-dissolving propellants, the introduction of the propellant can be accelerated, but this occurs in this case, a too strong ouelling can easily be poured in, whereby a coherent dough-like mass is formed, which is not very suitable for further processing.

It has now been found that blowing agent-containing styrene polymers can be produced in a technically simple manner can, if you have styrene polymers and they are non-dissolving or at most cjuellende, highly volatile organic liquids in closed vessels under the pressure of an inert gas at temperatures above the boiling point of the liquids mentioned above and the softening point the styrene polymer is heated and then allowed to cool while maintaining the pressure.

It is surprising that with this procedure, even without stirring, a homogeneous distribution of the liquid blowing agent enters the styrene polymer, although the styrene polymer is in the solid state cannot be dissolved by these propellants. The preferred styrene polymer is polystyrene, also copolymers of styrene with α-methylstyrene, Vinyl carbazole, acrylic esters, acrylonitrile and the like.

Process for the production of
propellant-containing styrene polymers

Applicant:

Aniline & Soda Factory in Baden
Aktiengesellschaft, Ludwigshafen / Rhein

Dr. Fritz Stastny, Weinheim (a. D. Bergstrasse),

and Dr. Rudolf Gäth, Ludwigshafen / Rhine,

have been named as inventors

into consideration. The styrene polymers to be treated should expediently be in fine-grain form, preferably with a particle size between 0.5 and 5 mm.

Petroleum ether, cyclohexane, Hexane and other aliphatic and cycloaliphatic hydrocarbons with boiling points suitable between 30 and 80 °. The amount of blowing agent can be between 1 and 15%, based on syrene polymer, vary depending on the desired propellant content. The pressure of the inert gases should expediently between during the heating of the mixture of blowing agents and styrene polymers 10 and 30 atmospheres. As indifferent gases you can z. B. Use carbon dioxide or nitrogen. For Mixtures of polystyrene and volatile aliphatic or cycloaliphatic hydrocarbons the most suitable treatment temperatures are between 130 and 190 °.

About the penetration of the non-dissolving or at most swelling blowing agents into the styrene polymers to facilitate, you can give them small amounts of solvents for styrene polymers, z. B. methylene chloride or benzene, add.

The propellant-containing masses obtained after cooling can be removed by evaporation of the liquid Blowing agents are foamed. You can first crush these masses and the obtained Sinter individual particles in perforated molds with heating to form porous moldings. The porous Shaped bodies or masses can be used as insulation materials, lightweight construction materials, floating bodies, toys and the like can be used.

The parts given in the examples below are parts by weight.

7® 546/44 +

example 1

900 parts of fine-grained polystyrene are placed in an open, cylindrical metal can 80 parts of hexane mixed intimately. The can is now placed in a gas-tight autoclave and the Autoclave put under a pressure of 10% carbon dioxide. The autoclave is then set to 140 ° for 4 hours heated, cooled while maintaining the carbonic acid pressure and removed the can. It contains a compact, cylindrical shaped body in which the hexane is homogeneously distributed. After chopping this molded body can be used to the fine-grained material obtained in perforated molds Foam porous objects.

Example 2

In a metal container with a square cross-section with a volume of 2000 ecm and is open at the top, 1000 g of finely ground polystyrene are introduced and mixed with a mixture from 65 g of petroleum ether with a boiling point of 54 to 60 ° and 5 g of methylene chloride are intimately mixed. The aluminum container is placed in a gas-tight pressure autoclave and, after the autoclave has been closed, a Exposed to nitrogen pressure of 15 atmospheres. The autoclave is then heated to 180 ° for 3 hours and cooled while maintaining the nitrogen pressure. The metal container is removed. It has become a compact block of propellant Formed polystyrene. This block is sawn into 15 mm thick slices and the slices for 20 minutes stored under water at 95 °. A porous plate with a specific weight of 0.06 is obtained. the Pores are very fine and even. Tapes can be cut from the porous plate to serve as insulating material in electrical engineering, e.g. B. for the production of radio frequency or television cables used can be.

Example 3

1500 g of a copolymer of 90 parts of styrene are placed in a tin can with a capacity of 2500 ecm and 10 parts of acrylonitrile, which is in the form of a fine powder, with a mixture consisting of from 120 g of petroleum ether with a boiling point of 35 to 50 °, 15 g of benzene and 15 g of methylene chloride, intimately

40

45 mixed. The can is placed in a pressure autoclave and exposed to a pressure of 8 atmospheres of carbon dioxide. The autoclave is then heated to 170 ° for 5 hours, cooled while maintaining the carbonic acid pressure and the can is then removed. A compact cylindrical shaped body has been formed from the copolymer containing blowing agent. This is mechanically comminuted so that particles 2 to 5 mm in width or length are produced. 100 parts of this comminuted mass are stored in water at 95 ° for 3 minutes. There is a considerable increase in volume with the formation of a porous structure. The bulk volume of the granulated material changes from 500 g / 1 to 60 g / l. The porous particles are used as insulating material in refrigeration, e.g. B. used for filling between walls.

On the other hand, the foamed or porous particles can also be processed into a porous plate be by placing them in a closed form, into which in the cavity · from all sides steam can be blown in, exposed to the action of water vapor at 110 ° for 30 seconds. After cooling, a molded body with a specific weight of 0.06 is obtained, which is used as an insulating material or can be used as a cork replacement product in general.

Claims (1)

Claim Process for the production of blowing agent-containing styrene polymers which are used to produce highly porous masses or moldings are suitable, characterized in that styrene polymers and they do not dissolve or at most swell, volatile organic liquids in closed vessels under a pressure of an inert gas that does not exceed 30 atm Temperatures above the boiling point of the liquids and the softening point of the Heated polymers and then allowed to cool while maintaining the pressure. Considered publications:
British Patent No. 657,338;
U.S. Patent No. 2,515,250. © 709 5W444 5.57