CS212645B1 - Process for producing a modified polyamide - Google Patents

Abstract

The purpose of the invention is a method for producing a modified polyamide, in which a lactam or a mixture of omega-amino acid lactams is subjected to anionic activated polymerization in the presence of red phosphorus homogeneously dispersed in the reaction mixture, which is manifested in particular by non-flammability. Its essence lies in the fact that the polymerization is carried out below the melting point of the polymer and the polymerization catalyst is sodium lactam aluminate of the general formula NaAl(OCH2CH2OCH3)x[CO(CH2) Ν]4_χ , where x = 2 or 0, y = 3 to 11, i.e. sodium caprolactam aluminate. It is advantageous if sodium dihydro-bis(2-methoxyethoxy)aluminate is added to the reaction mixture.

Description

The present invention provides a process for the manufacture of a modified polyamide, wherein the lectam or omega-amino acid lactam mixture is subjected to anionic activated polymerization in the presence of red phosphorus homogeneously dispersed in the reaction mixture.

The current development of technology increasingly requires the introduction of new polymer materials with properties better suited to the requirements of the polymers produced so far. A prospective way to obtain these polymers is to modify the basic types of α1 by chemical or physical means.

Thanks to their physico-mechanical properties, polyamides have become a sought-after construction and fiber material. The most widespread are polyamides based on 6-caprolactam and polycondensates of dlamine with dicarboxylic acid. The modification succeeded in reducing or eliminating some deficiencies in properties, such as low toughness, narrow melting interval, stability of the polymer against various influences, coloring in the mass, etc.

The invention is focused on solving problems of flammability of polyamides. In practice, the issue of reducing flammability is given considerable attention. For polyamides based on polycondensates of various diamines and dicarboxylic acids, heat-resistant and non-flammable polymers have been obtained either by synthesis of starting materials containing incorporated aromatic nucleus or phosphorus atoms (British Pat. 1,012,009, Japanese Pat. 73,20040, Ger. Offen 2). No. 542,053), or by post-treatment of the finished polymer (typically in the form of a fiber) with the flight capable of producing the desired retarding effect. These include, for example, substances containing halogen, nitrogen, inorganic elements and in particular organic phosphorus compounds.

Omega-amino acid lactam-based polyamides have also been modified by a number of phosphorus compounds such as phosphines, phosphine oxides, esters, phosphoric acid, etc., by adding them to the starting reaction mixture. In the vast majority of cases, however, the question of flame retardation is solved by adding flame retardants to the finished polymer. Additions of a combination of red phosphorus with synthetic resin, polycarbonate or the like, or substances containing phosphorus incorporated in their molecule are also used.

The addition of flame retardants to the finished polymer is usually accompanied by a number of complications such as homogenization issues, melt stability, preservation of other desirable properties, and is therefore an attempt to address the observed effect directly in polyamide synthesis. This pathway has also been shown to be feasible in the case of polyamide prepared by anionic activated polymerization of the omega-amino acid lactams, where the problem of reducing flammability and non-flammability has been addressed by adding red phosphorus to the lactam melt. The catalytic systems of anionic polymerization of lactams used so far are extremely sensitive to trace amounts of impurities and moisture. Therefore, the polymers thus prepared are strongly influenced in their properties and parameters by many of these influences and the same applies to the control and course of the polymerization processes themselves.

These drawbacks and problems are overcome by an inventive process for the production of a modified polyamide, wherein 6-caprolactam or a mixture thereof with 7 to 12 C-omega amino acid lactams is subjected to anionic activated polymerization in the presence of scattered red phosphorus in the melt of the reaction mixture. The invention consists in the fact that the polymerization is conducted above the melting point of the polymer at a temperature from 463 to 543 K and the polymerization catalyst is laktamohlinitan sodium formula NaAl (0CH ₂ CHgQCHj) * ^[C ° fCHg) y] ^ _ _x where x = 2 or 0, y = 3 to 11, preferably 5, i.e. sodium caprolactam aluminate.

It is particularly preferred that sodium dihydridobis (2-methoxyethoxo) aluminate is added to the reaction mixture. The red phosphorus may be added to the lactams in the form of a homogeneous mixture with the lactam and the amount added is from 0.1 to 3% by weight. based on the weight of the resulting reaction mixture. For flame retardant treatment, it is advisable to use a large surface red phosphor for polyamide, as its efficiency increases with increasing surface area. In addition, it is easier to disperse homogeneously in the lactam melt or reaction mixture. It is advantageous, especially from the viewpoint of safety, not to work with red phosphorus alone, but with its homogeneous mixture with lactam.

In this mixture, phosphorus can be freed of residual water, which is a known inhibitor of anionic polymerization of lactams, by distilling off the lactam front, 10-15% by weight, under reduced pressure.

As the optimal catalyst of the polymerization described for the preparation of the modified anionic polymer, sodium lactamaluminate is capable of fulfilling its function even under conditions where standard catalyst systems fail because they are more resistant to the inhibitory action of residual moisture and impurities. This makes it possible to prepare non-flammable polyamides by anionically activated polymerization of lactams with a higher red phosphorus content.

The invention and its effects are explained in more detail in the following examples.

He did

1.3 kg of a homogeneous mixture of 6-caprolactam and red phosphorus were added to 100 kg of the 6-caprolactam melt mixed in a stainless steel container under an inert content of 40% by weight. and the mixture was homogenized. At the same time, 0.8 wt. a cyclic phenyl isocyanate trimer as a polymerization activator. 0.3 mol% was metered into the mixer transported to the mixer upstream of the polymerization reactor at 413 K. sodium aluminate dihydrido-bis (2-methoxyethoxo). Polymerization was performed at 503 K. The resulting granulate polymer was evaluated as non-flammable after extraction with water and after drying according to CSN 3 456 15 and CEE / 031-SEC / F135 / 74 RLC-5.

Example 2

From a container containing a mixture of 6-caprolactam and 12-laurolactam, at a weight ratio of 975: 0.5 and 0.5 mol%. % of toluene diisocyanate, the melt in the mixer was contacted with a melt of lactam and red phosphorus and 0.25 mol%. Sodium aluminate dicaprolactamobis (2-methoxyethoxo) so as to provide a 1.5 wt. of red phosphorus. The polymer obtained by polymerization at 5'3 K was insoluble in m-cresol. After extraction in water and drying, it was determined to be non-flammable according to the standards given in Example 1.

Example 3

The procedure of Example 1, except that 0.35 mol% was used as the catalyst. sodium tetracaprolactam aluminate and the red phosphorus content was 2.65% by weight. After completion of the polymerization, the polymer was dopolymerized at 448 K and evaluated. The polymer content was 98.4% by weight, the polymer was insoluble in m-cresol and was designated as non-flammable.

Claims (2)

OBJECT OF THE INVENTION A process for the production of a modified polyamide, wherein 6-caprolactam or a mixture thereof with 7 to 12 C-omega amino acid lactams of the cycle is subjected to anionic activated polymerization in the presence of red phosphorus dispersed in the reaction mixture, The polymerization is carried out at a temperature of from 463 to 543 K in the presence of sodium lactamaluminate of the formula NeAltOCHgCHgOCH2Jjj2COtCH2J2Nj where x = 2 or 0, y = 3 to 11, preferably y = 5 as polymerization catalyst. 2. A process according to claim 1, wherein the polymerization is carried out in the presence of sodium dihydrobis (2-methoxyethoxo) aluminate.