DE1105166B - Process for the production of foamable polyamides - Google Patents

Description

It has already been proposed a method for producing foam-shaped polyamides in which the polycondensation of the substances forming linear polyamides in the presence of a mixture of carboxylic acid esters, whose alcohol components have 1 to 6 carbon atoms, and made oxyalkylalkylenediamines will. The reaction mixture is heated to temperatures which are generally 5 to 80 ° C. higher than the temperatures at which experience has shown that the polyamide formers alone are condensed.

It has now been found that foamable polyamides can be obtained at will by later Heating can be foamed if you use the mixture of polyamide formers, carboxylic acid esters and Oxyalkylalkylenediamines so long heated to temperatures at which polycondensation, but still no significant foaming occurs until the polycondensates formed are at least partially are soluble in concentrated sulfuric acid.

The oxyalkylamines and esters are generally used in approximately equimolecular amounts, however, it may be advisable to use an excess of one component. Should the foamable polyamide for example deliver a particularly plastic foam, an excess is used Oxyalkylamine.

The amount of the mixture of oxyalkylalkylenediamine and carboxylic acid esters that form the polyamide is added, depends on the type of polyamide used and on the type of Polyamide foam that is to be created when the foamable polyamide is subsequently heated. It amounts to about 1 to 10% mixture, based on polyamide-forming starting material. This amount can can easily be determined by preliminary tests.

The mixtures of oxyalkylalkylenediamines and carboxylic acid esters are the polyamide formers or added during the polycondensation. For intimate and even mixing of the components must be taken care of. The polycondensation can take place under normal pressure, increased or decreased Printing. It can be carried out with or without a solvent, with or without catalysts will.

The foamable polyamides are produced by heating the mixtures in an oxygen-free atmosphere to 150 to 300 ° C., preferably 160 to 250 ° C. The formation temperatures are generally lower than the temperatures which experience has shown to be maintained during the polycondensation of the polyamide formers. The duration of the heating depends essentially on the foaming capacity that is to be achieved. It can easily be determined through preliminary tests. In any case, method of manufacture
of foamable polyamides

Applicant:

Aniline & Soda Factory in Baden

Stock corporation,

Ludwigshafen / Rhine

Dr. Friedrich Becke, Heidelberg,

and Dr. Kurt Wick, Ludwigshafen / Rhine,

have been named as inventors

it may only be chosen so large that the resulting polycondensate is at least at room temperature is partially still soluble in concentrated sulfuric acid. Shorter heating time leads to more foamable polyamides, longer duration at the same temperature for less foamable Polyamides. However, it is possible to achieve the same foaming ability by heating for a shorter period of time at a higher temperature as can be achieved by prolonged heating at low temperature.

During the production of the foamable polyamides, a homogeneous one is only formed for a short time Melt, generally a tough, plastic mass is formed during the polycondensation, from which the Any water that may be released during the polycondensation can only escape with difficulty. It is therefore especially when producing larger quantities of foamable polyamides, this mass is important at least to mix occasionally. Appropriately, this is achieved in a vessel with a strong Agitator or by making the production in a heatable kneader. The foamable Masses that are produced by the method according to the invention can be heated by heating too porous in an oxygen-free atmosphere at temperatures higher than their formation temperatures Foam bodies. It is advisable to crush the foamable polyamides into powders, before they are foamed in any shape by the action of heat. So plates, rods, Solid and hollow bodies can be produced in a variety of forms. The foam bodies can be sawed, drilled,

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nail, screw or weld. They have great strength and toughness.

The parts mentioned in the examples are parts by weight.

example 1

100 parts of adipic acid hexamethylenediamine, 1.8 parts of N- (oxyethyl) -hexamethylenediamine, 2.2 parts Terephthalic acid dimethyl ester are mixed well and provided with a powerful stirrer Stainless steel vessel in an oxygen-free atmosphere initially at 200 ° C for 60 minutes, then 30 minutes heated to 250 ° C. After cooling, a colorless, lumpy mass with a K value of 54 is obtained. This Mass can be crushed to a powder by adding solid carbon dioxide. The powder forms, heated in a mold under pure nitrogen for 3 hours at 275 ° C, a foam body from Volume weight 0.28 with a uniform pore structure throughout.

Example 2

100 parts of adipic hexamethylenediamine, 1.6 parts of N, N'-bis (oxyethyl) hexamethylenediamine, 1.6 parts of diethyl adipate are in a kneader in an oxygen-free atmosphere for 4 hours heated to 200 ° C for a long time. This foamable polyamide (K value 53) can be heated up 280 ° C a uniform foam body with a density of 0.24 can be obtained.

Example 3

Parts of adipic acid hexamethylenediamine, 40 parts of caprolactam, 2.9 parts of N, N'-bis (oxypropyl) -hexamethylenediamine, 42 parts of monomethyl adipate are stored in an oxygen-free atmosphere for 8 hours heated to 180 ° C for a long time. The resulting foamable polyamide forms when heated to 275 ° C a foam body with a density of 0.19.

Claims (1)

Claim: Process for the production of foamable polyamides by polycondensation of polyamide formers in the presence of 1 to 10 percent by weight, based on polyamide-forming starting material, a propellant mixture of carboxylic acid esters, the alcohol components of which have 1 to 6 carbon atoms, and N-oxyalkylalkylenediamines, characterized in that a mixture of polyamide formers and 1 to 10 percent by weight of a blowing agent mixture from the carboxylic acid esters and N-oxyalkylalkylenediamines in an oxygen-free atmosphere with the formation of concentrated sulfuric acid at least partially soluble polyamides is polycondensed at 160 to 250 ° C. © 109 577/433 4.61