Flame-proofed moulding materials

Details Flame-proofed moulding materials Flame-proofed moulding materials

1999-04-14

2000-08-15

Dawson, Robert

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

524601, 524605, 524101, 524139, 524137, 524154, 524442, 428921, C08K 332

Patent

active

061037974

DESCRIPTION:

BRIEF SUMMARY
The invention relates to thermoplastic molding compositions comprising retardant which contains phosphorus in the valence state -1, -2 or -3, 100%.
The invention also relates to the use of the novel molding compositions to produce fibers, films or shaped articles, and to the shaped articles of any type thus obtained.
The market shows increasing interest in halogen-free flame-retardant polyesters. Important requirements of the flame retardant are: pale intrinsic color, sufficient thermal stability for incorporation in thermoplastics, and its efficacy in reinforced and non-reinforced polymers (wicking effect of glass fibers).
The UL 94 flammability test should be passed at the V-0 level for non-reinforced polyesters.
For reinforced polyester, it is sufficient for many applications that the glowing-wire test is passed.
In principle, besides halogen-containing systems, four halogen-free FR systems are used in thermoplastics: effective. efficacy in thermoplastics, eg. polyamide. In reinforced polyamide, it is effective only in combination with shortened glass fibers. In polyesters, melamine cyanurate is not effective. polyesters. melamine phosphates, which have insufficient thermal stability for thermoplastics processed above 200.degree. C.
JP-A 03/281 652 discloses polyalkylene terephthalates containing melamine cyanurate and glass fibers and also a phosphorus-containing flame retardant. The latter contains phosphoric acid derivatives, such as phosphoric acid esters (valence state +5), which when subjected to thermal stress cause transesterification of the polyester and degradation of the polymer matrix.
These disadvantages are also apparent for the combination of melamine cyanurate with resorcinol bis(diphenylphosphate) disclosed in JP-A 05/070 671.
It is an object of the present invention to provide flame-retardant polyester molding compositions which achieve the UL 94 classification V-0 or pass the glowing-wire test. They should be capable of being processed with virtually no degradation or transesterification of the polymer matrix.
We have found that this object is achieved by means of the thermoplastic molding compositions defined at the outset. Preferred embodiments are given in the subclaims.
The novel molding compositions comprise, as component (A), from 30 to 97% by weight, preferably from 40 to 93% by weight, and in particular from 50 to 85% by weight, of a thermoplastic polyester.
Polyesters which are used are generally based on aromatic dicarboxylic acids and an aliphatic or aromatic dihydroxy compound.
A first group of preferred polyesters consists of polyalkylene terephthalates having from 2 to 10 carbon atoms in the alcohol moiety.
Polyalkylene terephthalates of this type are known per se and are described in the literature. They contain, in their main chain, an aromatic ring which derives from the aromatic dicarboxylic acid. The aromatic ring may also be substituted, for example with halogen, such as chlorine or bromine, or with C.sub.1 -C.sub.4 -alkyl, such as methyl, ethyl, isopropyl or n-propyl, n-butyl, isobutyl or tert-butyl.
These polyalkylene terephthalates can be prepared by reaction of aromatic dicarboxylic acids, their esters or other ester-forming derivatives with aliphatic dihydroxy compounds, in a manner known per se.
Preferred dicarboxylic acids are, for example, 2,6-naphthalenedicarboxylic acid, terephthalic acid and isophthalic acid or mixtures of these. Up to 30 mol%, preferably not more than 10 mol%, of the aromatic dicarboxylic acids may be replaced by aliphatic or cycloaliphatic dicarboxylic acids, such as adipic acid, azelaic acid, sebacic acid, dodecanedioic acids and cyclohexanedicarboxylic acids.
Preferred aliphatic dihydroxy compounds are diols having from 2 to 6 carbon atoms, in particular 1,2-ethanediol, 1,4-butanediol, 1,6-hexanediol, 1,4-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethylanol and neopentyl glycol, and mixtures of these.
Particularly preferred polyesters (A) are, for example, polyalkylene terephthalates derived from alkanediols having from 2 to

REFERENCES:
patent: 3609118 (1971-09-01), Pitz
patent: 3671487 (1972-06-01), Abolins
patent: 4180496 (1979-12-01), Yanagimoto et al.
patent: 4866114 (1989-09-01), Taubitz et al.
JP Abstract 3/281652.
JP Abstract 5/070671.

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