DD271335A1 - FLAME PROTECTION FOR POLYAMIDE - Google Patents

Abstract

The invention relates to a flame retardant for the stabilization of polyamide. The object of the invention is the use of a flame retardant for polyamide, which has a good flame retardancy while maintaining the good mechanical and electrical properties of the polyamide and is available in technical quantities. Another task is the good incorporability of the flame retardant. As a flame retardant, a batch of 2,4-dioxohexahydro-1,3,5-triazine is used in ethylene-vinyl acetate copolymer.

Description

Characteristic of the known state of the art

In accordance with the increasing safety requirements, design and finished parts are required to an increasing extent, which are flame-retardant and have self-extinguishing properties. This prevents fire spreading in case of fire. Polyamide 6 molds do not meet these requirements. Therefore, the flammability of the polyamide-6 molding compositions is reduced by the addition of special flame retardants. There are a variety of technical solutions for this purpose. The use of halogen-containing flame retardants whose effectiveness by the addition of metalloids, z. As antimony trioxide is increased, is eliminated because the electrical utility properties (eg.

Tracking resistance) of the molded parts are minimized by these combinations. In case of fire, corrosive hydrogen halide compounds form, which cause further unpleasant technical consequences on the surrounding or adjacent moldings.

Halogen-free flame retardant combinations are known to comprise five groups of substances, the first group - triazine compounds (melamine) - being recommended especially for polyamides. According to DD 74097 or DD 135207, the use of up to 60% melamine, based on polyamide. In particular, the achieved mechanical properties do not meet the new requirements and require in the molding production close processing sizes and lead in coloring, especially in the color gray, for a considerable reduction in the impact resistance.

The second group includes flame retardant combinations with red phosphorus. The excellent effect of this combination, however, in addition to the red inherent color has the disadvantage that formed during the thermoplastic processing toxic phosphine and released.

Diu diitte group 'salt-like organophosphorus Verbir fertilize or combinations with phosphorus salts (DE 2806049,2915116,28.0549,2523145, J 50075657, 5,585,654, EP 37383), whereby the creep resistance is considerably reduced.

The fourth group is based on alkali and alkaline earth salts of organic monomeric and polymeric sulfonic acids (DE 2918534, 2458510, US 3888822), which also limit the performance of the material.

In the fifth group weroen oxides, borates and other inorganic compounds detected (US 3985928.4036806, DE 262 ^ 902).

Object of the invention

The aim of the invention is the use of a substance which has a high flame retardancy and is available in industrially applicable amounts.

Explanation of the essence of the invention

The invention has for its object to use as a flame retardant for Polyepsiloncaprolactam a triazine compound in a modification that ensures safe incorporation and stable processing of the polyamide molding composition. This object is achieved by a flame retardant for polyamide, in particular for polyamide 6, based on a triazine additive, by according to the invention the polyamide 7 to 10.5% (mass), based on modified polyamide, 2,4-Dioxohexahydro-1.3 , 5-triazine in the form of a batch, said batch comprising 40 to 60% (mass) of 2,4-dioxohexahydro-1,3,5-triazine and 60 to 40% (by weight) of an ethylene-vinyl acetate copolymer a vinyl acetate content of 15 to 30% (mass). 2,4-dioxohexahydro-1,3,5-triazine melts at 563K with addition (Piskalla, Collection of Czechoslovakia Chemical Communication 26 [1961] p. 2519,2523), but gaseous decomposition products already occur above 462 K. This instability is accelerated especially in the presence of bases (Ch. Grundmann, Angew. Chemie 75 (1963), pp. 393-407), so that a use of 2.4 dioxohexahydro-1,3,5-triazine in basic melts above 500K Thus, in pure form, it does not possess the sufficient stability for incorporation in polyamide.

Contrary to expectations, occurs at the high processing and Hersteliungstemperaturen of the polyamide, d. H. at temperatures> 530K, no decomposition, which is reflected in the excellent mechanical properties of the molded parts.

-2- 271335 exemplary embodiments

Examples 1 to 4

A polyamide 6 (PA6) having the properties given in the table under No. 1 was processed according to the invention into the following mixtures:

No. 2 86.6% (mass) PA 6

7.5% (mass) 2,4-dioxohe. shydro-1,3,5-triazine (DHT)

5.9% (mass) of ethylene vinyl acetate copolymer having a vinyl acetate content of 18% (EVA), No. 3 81.2% (by mass) PA 6 10.5% (by weight) of DHT

8.3% (by mass) of EVA with a vinyl acetate content of 28%.

For comparison, a mixture of 91.7% (mass) PA6 and 8.3% (mass) EVA without DHT was tested under # 4. The properties are given in the table.

Belspiel5.

A twin-screw extruder with the temperature profile between 407 Kund 452 K, whereby due to the friction a max. Melt temperature of 472 K occurs, at a speed of 200U / min, a mixture consisting of 44% 2,4-dioxohexahydro-1,3,5-triazine and 56% polyethylene-vinyl acetate copolymer having a vinyl acetate content of 15% abandoned and melted. The strands arising at the strand tool are granulated after cooling in a water bath. The batch obtained is pourable and ready for immediate use.

Table: Execution games

No. Biegefe Modulus Shock oscillations O ₂ - UL 94- stigkeit TGL 39,782 bending dung index test TGL14067 strength strength TGL22239 step ness (1.6mm thick PK) N / mm ² N / mm ² J / mm ² % % 1. 110 2 550 does not break 1.10 22 HB Second 110 2795 3x br. n. "7 * 5 1.08 29 V1 Third 108 2675 / O 70 1.13 30 VO 4th 100 1850 does not break 1.40 22 HB

Claims (1)

Flammschulzmittel for polyamide, in particular for polyamide 6, based on a triazine, characterized in that the polyamide 7 to 10.5% (mass), based on modified polyamide, 2 /, - dioxohexahydro-1,3,5-triazine in the form 40 to 60% (by weight) of 2,4-dioxohexahydro-1,3,5-triazine and 60 to 40% (by weight) of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 15 to 30%. Contains (mass). Field of application of the invention The invention relates to the use of a flame retardant for Polyepsiloncaprolactamformmassen for Flammschutzausrüsiung.