DE1082402B - Process for the production of large-pored foams - Google Patents

Description

Process for the production of coarse-pored foams It is known that one foams from polymers or mixed polymers of vinyl chloride or vinylidene chloride can produce. This is usually done in such a way that the Polymer - optionally mixed with plasticizer - together with a stabilizer and a propellant, and optionally further additives, in one on all sides closed form under pressure up to the decomposition temperature of the propellant and the gelling temperature of the polymer is heated, then cooled in the mold and is expanded under atmospheric pressure at about 100 ° C.

Preferred propellants here are those compounds which split off nitrogen when they decompose. Such propellants are e.g. B. azo compounds, such as azoisobutyric acid dinitrile, azodicarbonamide or sulfohydrazides, such as. B. Diphenylsulfone-3, 3'-disulfohydrazide, benzene-1, 3-disulfohydrazide or N-nitroso compounds, such as z. B. dinitrosopentamethylenetetramine, dinitrosodimethylterephthalamide or others nitrogen-releasing compounds.

The pore size of the foams obtained in this way is the first Line determined by the type of propellant used. It is observed that it depends on the decomposition temperature of the propellant and its solubility in the plastic mixture and its gelation rate. It succeeds on relatively simple way to produce foams with a very fine pore structure, by adding pigment or rapidly gelling plasticizers, such as. B. tricresyl phosphate, can be used. In contrast, with a given blowing agent, the pores can only be enlarged to a very small extent, e.g. B. by varying the plastic mixture or changing the foaming conditions. Achieving large pores is essential however, for some technical reasons (e.g. better slip resistance, larger pores Foams, etc.) are very desirable. One also strives when using a and the same blowing agent as different pore sizes as possible in the foam to be able to hire.

It has now been found that you can make foams from polymers or Contains copolymers of vinyl chloride or vinylidene chloride with large pores, if the molding compound contains small amounts of water during the usual foaming. Surprisingly, they become essential when foaming in the presence of water larger pores achieved than in the absence of water.

The pore-enlarging effect of the addition of water already occurs small additions of water. In general, however, it will give the best results achieved when the addition of water is 2 to 10 percent by weight of the mixture to be foamed amounts to. Furthermore, it has been shown that it can be advantageous if one to the Water still adds surface-active substances that allow better mixing of the Ensure water in the substances to be foamed. As a surface-active Substances are all those compounds that are capable of reducing surface tension to change the water or the plastic mixture to be foamed, d. H. anion and cationic and nonionic compounds and z. B. silicone oils.

The surface-active substances can be added to the water in quantities from Z. B. 10 to 40 ° / 0 can be added.

Example A paste consisting of 100 parts by weight of one in emulsion manufactured polyvinyl chloride (K value 66-75), 100 parts by weight plasticizer, 0.7 parts by weight of stabilizer and those given in the table below Quantities (in percent by weight, based on the mixture listed above) Propellant and water, optionally with the additional use of a surface-active one Compound, was mixed homogeneously on a three-roll mill, into a sealable one Form (100-100-10 mm) filled and heated in the press to 165 ° C for 10 minutes. After the mold had cooled, the blank was placed in a circulating air heater for 20 minutes Heated to 100 ° C, whereby the foam got its final size.

The pores of the foams obtained had the diameters shown in the table below: Propellant Addition in Additives Addition on average Weight-weight pore diameter Art percent Art percent (mm) Diphenylsulfone-3,3'-disulfohydrazide 15 none 0.1 to 0.25 Diphenylsulfone-3,3'-disulfohydrazide 15 Water 5 0.6 to 0.8 Diphenylsulfone-3, 3'-disulfohydrazide 15 15% aqueous solution of a sulfo-3 0.6 to 0.8 nated alkylphenol polyglycol ether Diphenylsulfone-3, 3'-disulfohydrazide 15 15% aqueous solution of a sulfo-5 1, 2 to 1, 5 nated alkylphenol polyglycol ether Diphenylsulfone-3, 3'-disulfohydrazide 15 35% aqueous emulsion of a 5 1, 6 Methylpolysiloxane Diphenyloxyd-4,4'-disulfohydrazide 15 none 0.1 to 0.3 Diphenyloxyd-4,4'-disulfohydrazide 15 150 / oigne aqueous solution of an alkyl-5 0.8 to 1.0 phenol polyglycol ethers Azoisobutyric acid dinitrile 10 none 0, 5 Azoisobutyric acid dinitrile ......... 10 15% aqueous solution of a sulfo-5 1 to 1, 3 nated aryl polyglycol ethers Morpholylthiocarboxylic acid azide 10 none 0.65 Morpholylthiocarboxylic acid azide .... 10 15% aqueous solution of a sulfo- 5 1 to 1.3 nated oleic acid dibutylamide PATENT CLAIM: 1. Process for the production of coarse-pored foams from polymers or copolymers of vinyl chloride or vinylidene chloride by heating a plastic containing blowing agent

Claims (2)

resin-plasticizer paste according to methods known per se, characterized in that that the paste contains about 2 to 10 percent by weight of water. 2. The method according to claiml, characterized in that the paste additionally contains surface-active compounds.