Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-11-02
2003-01-07
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S126000
Reexamination Certificate
active
06503969
ABSTRACT:
The invention relates to thermoplastic molding compositions, comprising
A) from 5 to 96% by weight of a polyester,
B) from 1 to 30% by weight of a nitrogen compound, excluding melamine cyanurate,
C) from 0.1 to 30% by weight of a phosphinate of formula I or of a diphosphinate of formula II or of polymers of these or mixtures of these
where:
R
1
and R
2
are hydrogen, linear or branched alkyl having from 1 to 6 carbon atoms or phenyl, with the proviso that at least one of the radicals R
1
and R
2
is hydrogen,
R
3
is linear or branched C
1
- to C
10
-alkylene or is arylene, alkylarylene or arylalkylene,
M is an alkaline-earth metal or alkali metal, Al, Zn, Fe or boron,
m is an integer from 1 to 3,
n is an integer from 1 to 3, and
x is 1 or 2
D) from 0 to 5% by weight of at least one ester or amide of saturated or unsaturated aliphatic carboxylic acids having from 10 to 40 carbon atoms with saturated aliphatic alcohols or amines having from 2 to 40 carbon atoms, and
E) from 0 to 60% by weight of other additives,
where the total of the percentages by weight of components A) to E) is 100%.
The invention further relates to the use of the novel molding compositions for producing fibers, films or moldings, and also to the resultant moldings of any type.
The market is increasingly interested in halogen-free flame-retardant polyesters. Significant requirements placed upon the flame retardant are: pale intrinsic color, adequate heat stability for incorporation into thermoplastics, and also effectiveness in reinforced and unreinforced polymer (wicking effect of glass fibers).
The UL 94 fire test for unreinforced polyesters should be passed here at the V-0 level. For reinforced polyesters, at least the V-2 classification should be obtained and/or the glow-wire test passed.
Besides the halogen-containing systems there are in principle four halogen-free FR systems used in thermoplastics:
Inorganic flame retardants, which have to be used in large amounts to be effective.
Nitrogen-containing FR systems, such as melamine cyanurate, which has limited effectiveness in thermoplastics, e.g. polyamide. In reinforced polyamide it is effective only in combination with shortened glass fibers. Melamine cyanurate by itself is not effective in polyesters.
Phosphorus-containing FR systems, which are generally not very effective in polyesters.
Phosphorus
itrogen-containing FR systems, such as ammonium polyphosphates or melamine phosphates, which do not have sufficient thermal stability for thermoplastics processed at temperatures above 200° C.
JP-A 03/281 652 has disclosed polyalkylene terephthalates which comprise melamine cyanurate and glass fibers, and also a phosphorus-containing flame retardant. These molding compositions comprise derivatives of phosphoric acid, such as phosphoric esters (valence state +5), which tend to bleed out on exposure to heat.
These disadvantages are also seen for the combination of melamine cyanurate (MC) with resorcinol bis(diphenyl phosphate), known from JP-A 05/070 671. These molding compositions also have high phenol values during processing and do not have adequate mechanical properties.
JP-A 09/157 503 has disclosed polyester molding compositions with MC, phosphorus compounds and lubricants, comprising less than 10% of reinforcing agents. Molding compositions of this type have flame-retardant and mechanical properties which are not fully satisfactory. The same applies to migration and phenol formation during processing.
EP-A 699 708, DE-A 19614424 and BE-A 875 530 have disclosed salts of phosphinic acid as flame retardants for polyesters.
WO 98/17720 has disclosed combinations of MC with phosphorus-containing compounds and lubricants for polyesters.
It is an object of the present invention to provide flame-retardant polyester molding compositions which achieve an adequate UL 94 classification and an improved LOI value. In addition there should be a very high degree of retention of mechanical properties. Thermal stability during processing should, furthermore, be improved, and phenol emission reduced.
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 5 to 96% by weight, preferably from 10 to 70% by weight and in particular from 10 to 60% by weight, of a thermoplastic polyester.
Use is generally made of polyesters based on aromatic dicarboxylic acids and on an aliphatic or aromatic dihydroxy compound.
A first group of preferred polyesters is that 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. Their main chain contains an aromatic ring which derives from the aromatic dicarboxylic acid. There may also be substitution in the aromatic ring, e.g. by halogen, such as chlorine or bromine, or by C
1
-C
4
-alkyl, such as methyl, ethyl, iso- or n-propyl or n-, iso- or tert-butyl.
These polyalkylene terephthalates may be prepared by reacting aromatic dicarboxylic acids, or their esters or other ester-forming derivatives, with aliphatic dihydroxy compounds in a manner known per se.
Preferred dicarboxylic acids are 2,6-naphthalenedicarboxylic acid, terephthalic acid and isophthalic acid, and 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, sebaccic acid, dodecanedioc acids and cyclohexanedicarboxylic acids.
Preferred aliphatic dihydroxy compounds are diols having from 2 to 6 carbon atoms, in particular 1,2-ethanediol, 1,3-propanediol, 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 polyalkylene terephthalates derived from alkanediols having from 2 to 6 carbon atoms. Among these, particular preference is given to polyethylene terephthalate, polypropylene terephthalate and polybutylene terephthalate, and mixtures of these. Preference is also given to PET and/or PBT comprising, as further monomer units, up to 1% by weight, preferably up to 0.75% by weight, of 1,6-hexanediol and/or 5-methyl-1,5-pentanediol.
The viscosity number of the polyester A) is generally in the range from 50 to 220, preferably from 80 to 160 (measured in 0.5% strength by weight solution in a phenol/o-dichlorobenzene mixture (in a weight ratio of 1:1 at 25° C.) in accordance with ISO 1628.
Particular preference is given to polyesters whose carboxyl end group content is up to 100 mval/kg of polyester, preferably up to 50 mval/kg of polyester and in particular up to 40 mval/kg of polyester. Polyesters of this type may be prepared, for example, by the process of DE-A 44 01 055. The carboxyl end group content is usually determined by titration methods (e.g. potentiometry).
Particularly preferred molding compositions comprise, as component A), a mixture of polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). The proportion of the polyethylene terephthalate in the mixture is preferably up to 50% by weight, in particular from 10 to 30% by weight, based on 100% by weight of A).
Novel molding compositions of this type have very good flame-retardant properties and improved mechanical properties.
It is also advantageous to use recycled PET materials (also termed scrap PET) in a mixture with polyalkylene terephthalates, such as PBT.
Recycled materials are generally:
1) Those known as post-industrial recycled materials: these are production wastes during polycondensation or during processing, e.g. sprues from injection molding, start-up material from injection molding or extrusion, or edge trims from extruded sheets or films.
2) Post-consumer recycled materials: these are plastic items which are collected and treated after utilization by the end consumer. Blow-molded PET bottles for mineral water, s
Fisch Herbert
Klatt Martin
Leutner Bernd
Nam Michael
BASF - Aktiengesellschaft
Keil & Weinkauf
Szekely Peter
LandOfFree
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