Flame and stress crack resistant polycarbonate molding...

Details Flame and stress crack resistant polycarbonate molding... Flame and stress crack resistant polycarbonate molding...

2000-02-04

2003-05-27

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...

C524S141000, C524S145000, C524S430000, C524S437000

Reexamination Certificate

active

06569930

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to flame-proof polycarbonate ABS moulding compositions containing phosphate compounds and inorganic materials which have excellent resistance to stress cracking.
BACKGROUND OF THE INVENTION
EP-A 0 174 493 (U.S. Pat. No. 4,983,658) describes flame-proofed, halogen-containing polymer mixtures consisting of aromatic polycarbonate, styrene-containing graft copolymer, monophosphates and a specific polytetrafluoroethylene formulation. Although these mixtures are adequate in terms of fire behaviour and level of mechanical values, shortcomings may arise as regards resistance to stress cracking.
U.S. Pat. No. 5,030,675 describes flame-proof thermoplastic moulding compositions consisting of aromatic polycarbonate, ABS polymer, polyalkylene terephthalate as well as monophosphates and fluorinated polyolefins as flame-proofing additives. Good resistance to stress cracking is contrasted by disadvantages in the form of shortcomings as regards notch impact strength and inadequate thermostability under high thermal load such as the processing process.
Diphosphates are known as flame-proofing additives. JA 59 202 240 describes the production of such a product from phosphorus oxychloride, diphenols such as hydroquinone or bisphenol A and monophenols such as phenol or cresol. These diphosphates may be used in polyamide or polycarbonate as flame-proofing agents. In this literature, however, there is no indication of improved resistance to stress cracking by addition of the oligomeric phosphate to polycarbonate moulding compositions.
EP-A 0 363 608 (=U.S. Pat. No. 5,204,394) describes polymer mixtures consisting of aromatic polycarbonate, styrene-containing copolymer or graft copolymer and oligomeric phosphates as flame-proofing additives. U.S. Pat. No. 5,061,745 describes polymer mixtures consisting of aromatic polycarbonate, ABS graft polymer and/or styrene-containing copolymer and monophosphates as flame-proofing additives. The level of the stress cracking resistance of these mixtures is often inadequate for the production of thin-walled housing parts.
EP-A 0 767 204 describes flame-proof polyphenylene oxide (PPO) and/or polycarbonate mixtures which contain a mixture consisting of oligophosphates (bisphenol A (BPA)-oligophosphate type) and monophosphates as flame-proofing agents. High flame-proofing agent contents lead to disadvantageous mechanical properties and reduced heat deflection temperature.
EP-A 0 611 798 and WO 96/27600 describe moulding compositions which contain oligomeric, terminally alkylated phosphoric acid esters of the BPA type in addition to polycarbonate. Because of the alkylation, high contents are required in order to achieve effective flame-proofing, and this is very disadvantageous for many technical application properties.
EP-A 0 754 531 describes reinforced PC/ABS moulding compositions which are suitable for precision components. Inter alia, oligophosphates of the BPA type are used as flame-proofing agents. The high filler contents have a very disadvantageous effect on the mechanical properties.
SUMMARY OF THE INVENTION
Surprisingly it has now been found that flame-proof polycarbonate ABS moulding compositions have excellent stress cracking resistance and notch impact strength as well as a high heat deflection temperature when they contain an additive combination consisting of a specific phosphorus compound and a synergistically acting quantity of one or more inorganic materials. A particularly favourable property combination is achieved when the phosphorus compound is made up of bisphenol A units. These moulding compositions are particularly suitable for producing thin-walled housing parts (data processing housing parts) where high processing temperatures and pressures lead to considerable stress on the material used.
The invention provides flame-proof thermoplastic moulding compositions containing
A. 40 to 98 parts by weight, preferably 50 to 95 parts by weight, particularly preferably 60 to 90 parts by weight of an aromatic polycarbonate,
B. 0 to 50, preferably 1 to 30 parts by weight, of a vinyl (co)polymer consisting of at least one monomer selected from the series styrene, &agr;-methylstyrene, ring-substituted styrenes, C
1
-C
8
-alkyl methacrylates, C
1
-C
8
-alkyl acrylates with at least one monomer from the series acrylonitrile, methacrylonitrile, C
1
-C
8
-alkyl methacrylates, C
1
-C
8
-alkyl acrylates, maleic anhydride, N-substituted maleinimides,
C. 0.5 to 60 parts by weight, preferably 1 to 40 parts by weight, particularly preferably 2 to 30 parts by weight of a graft polymer,
D. 0.5 to 20 parts by weight, preferably 1 to 18 parts by weight, particularly preferably 2 to 15 parts by weight of a phosphorus compound of formula (I)
in which
R
1
, R
2
, R
3
and R
4
independently of each other mean C
1
-C
8
alkyl optionally substituted by halogen, C
5
-C
6
-cycloalkyl, C
6
-C
10
-aryl or C
7
-C
12
-aralkyl optionally substituted by halogen and/or alkyl in each case,
n independently of each other means 0 or 1,
q independently of each other means 0, 1, 2, 3 or 4,
N means 0.1 to 5 and
R
5
and R
6
independently of each other mean C
1
-C
4
-alkyl, preferably methyl or halogen, preferably chlorine and/or bromine,
Y means C
1
-C
7
-alkylidene, C
1
-C
7
-alkylene, C
5
-C
12
-cycloalkylene, C
5
-C
12
-cycloalkylidene, —O—, —S—, —SO—, —SO
2
— or —CO—,
E 0.05 to 5 parts by weight, preferably 0. 1 to 1 part by weight, particularly preferably 0.1 to 0.5 parts by weight of a fluorinated polyolefin,
F. 0.01 to 50 parts by weight, preferably 0.1 to 20 parts by weight, particularly preferably 0.5 to 10 parts by weight of finely divided inorganic powder with an average particle diameter ≦200 nm.
The sum of all parts by weight A+B+C+D+E+F is 100.
DETAILED DESCRIPTION OF THE INVENTION
Component A
Thermoplastic aromatic polycarbonates suitable according to the invention according to Component A are those based on diphenols of formula (II)
in which
A is a single bond C
1
-C
5
-alkylene, C
2
-C
5
-alkylidene, C
5
-C
6
-cycloalkylidene, —S— or —SO
2
—,
B is chlorine, bromine,
q is 0,1 or 2 and
p is 1 or 0,
or alkyl-substituted dihydroxyphenyl cycloalkanes of formula (III)
in which
R
7
and R
8
independently of each other, in each case mean hydrogen, halogen, preferably chlorine or bromine, C
1
-C
8
-alkyl, C
5
-C
6
-cycloalkyl, C
6
-C
10
-aryl, preferably phenyl, and C
7
-C
12
-aralkyl, preferably phenyl-C
1
-C
4
-alkyl, particularly benzyl,
m means a whole number of 4, 5, 6 or 7, preferably 4 or 5,
R
9
and R
10
, individually selectable for each Z and independently of each other mean hydrogen or C
1
-C
6
-alkyl, and
Z means carbon, with the proviso that on at least one atom Z R
9
and R
10
simultaneously mean alkyl.
Examples of suitable diphenols of formula (H) are hydroquinone, resorcinol, 4,4′-dihydroxydiphenyl, 2,2-bis-(4-hydroxyphenyl)-propane, 2,4-bis-(4-hydroxyphenyl)-2-methylbutane, 1,1-bis-(4-hydroxyphenyl)-cyclohexane, 2,2-bis-(3-chloro-4-hydroxyphenyl)-propane, 2,2-bis-(3,5-dibromo-4-hydroxyphenyl)-propane.
Preferred diphenols of formula (II) are 2,2-bis-(4-hydroxyphenyl)-propane, 2,2-bis-(3,5-dichloro-4-hydroxyphenyl)-propane and 1,1-bis-(4-hydroxyphenyl)-cyclohexane.
Preferred diphenols of formula (III) are 1,1-bis-(4-hydroxyphenyl)-3,3-dimethyl-cyclohexane, 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethyl cyclohexane and 1,1-bis-(4-hydroxyphenyl)-2,4,4-trimethyl-cyclopentane.
Polycarbonates suitable according to the invention are both homopolycarbonates and copolycarbonates.
Component A may also be a mixture of the thermoplastic polycarbonates defined above.
Polycarbonates may be produced in known manner from diphenols with phosgene by the interface process or with phosgene by the process in homogeneous phase, the so-called pyridine process, wherein the molecular weight can be set in known manner by means of a corresponding quantity of known chain terminators.
Examples of suitable chain terminators are phenol, p-chlorophenol, p-tert.-butyl phenol or 2,4,6-tribromophenol, but a

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