Composition based on copolycarbonates

Details Composition based on copolycarbonates Composition based on copolycarbonates

2001-09-24

2003-06-24

Boykin, Terressa M. (Department: 1711)

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

Synthetic resins

From phenol, phenol ether, or inorganic phenolate

C528S198000, C525S067000, C525S146000, C525S148000, C525S468000, C524S117000, C524S119000, C524S123000, C524S125000, C524S127000, C524S139000, C524S140000, C524S141000, C524S145000

Reexamination Certificate

active

06583257

ABSTRACT:

The invention relates to thermoplastic polycarbonate compositions and moulded parts containing the latter having increased stress cracking resistance and thermal stability.
The stress cracking resistance of moulded parts fabricated from polymers is always important in their production and in the use of the moulded parts if they come into contact with oils, cleaning agents and alcohols. Particularly in automobile construction and other external applications moulded parts that are as resistant as possible to chemicals and that on the one hand are stable at low temperatures and on the other hand exhibit a high thermal stability have been sought for a long time. The object therefore existed of finding a polycarbonate blend that exhibits an improved stress cracking resistance and higher thermal stability compared to polycarbonate blends containing polycarbonate formed from pure 2,2-bis(4-hydroxyphenyl)-propane as bisphenol, and that on the other hand retains the advantageous properties of polycarbonate blends such as an excellent low temperature toughness.
Copolycarbonates based on 4,4′-dihydroxydiphenyl and 2,2-bis(4-hydroxyphenyl)-propane have already been described as being particularly resistant to chemicals, heat stable and difficultly inflammable (see JP-A 5 117 382, EP-A 0 544 407, U.S. Pat. Nos. 5,470,938, 5,532,324 and 5,401,826), and compared to commercially available polycarbonate formed from pure bisphenol A, have equally good mechanical properties and transparency. However, the prior art does not contain any indication that these copolycarbonates may advantageously be used in polycarbonate blends with retention of the particularly good low temperature properties.
JP-A 03 126 756 describes thermoplastic resin compositions having improved heat resistance, impact strength, and resistance to oil and water. These resins are composed of aromatic polyester resin, aromatic polycarbonate and butadiene rubber.
EP-A 0 403 837 describes thermoplastic polycarbonate moulding compositions based on substituted dihydroxydiphenylcycloalkanes, other aromatic polycarbonates, for example based on bisphenol A, and grafted, particulate diene rubbers, and their use for the production of thermoplastic moulded parts. On account of the dihydroxy-diphenylcycloalkanes these moulding compositions have an improved heat resistance while retaining a good notched impact strength.
The object of the present invention is to provide thermoplastic polycarbonate compositions having an improved stress cracking resistance and improved thermal stability.
This object is achieved by copolycarbonate compositions containing
A) 2 to 98, preferably 5 to 97, particularly preferably 30 to 95 parts by weight of a thermoplastic aromatic copolycarbonate built up from 0.1 mole % to 46 mole % of compounds of the formula (I)
 wherein
R
1
to R
8
independently of one another denote hydrogen, halogen, C
1
to C
8
alkyl, C
1
to C
5
cycloalkyl, C
6
to C
10
aryl and C
7
to C
12
aralkyl,
and complementary amounts, i.e. 99.9 mole % to 54 mole %, of diphenols different from the compounds of the formula (I),
B) 0.5 to 50, preferably 2 to 40, particularly preferably 5 to 30 parts by weight of at least one graft polymer of
B1) 5 to 90 parts by weight of at least one vinyl monomer and
B2) 95 to 10 parts by weight of a rubber having a glass transition temperature of ≦10° C.
It has surprisingly been found that even with a small proportion of structural units according to formula (I) in the polycarbonate composition, the stress cracking resistance of moulded parts obtained therefrom is significantly improved.
The copolycarbonates according to the invention preferably contain according to component A) 11 to 34 mole % and particularly preferably 26 to 34 mole % of compounds of the formula (I).
Diphenols that are different from the compounds of the formula (I) are accordingly contained in complementary amounts, i.e. 99.99 to 54 mole %, preferably 89 to 66 mole %, particularly preferably 74 to 66 mole %.
R
1
to R
8
in formula (I) independently of one another preferably denote hydrogen, C
1
-C
4
alkyl, phenyl, substituted phenyl or halogen, particularly preferably denote hydrogen, methyl or tert.-butyl, and particularly preferably all denote the same radical.
Particularly preferred compounds of the formula (I) are 4,4′-dihydroxydiphenyl (DOD) and 4,4′-dihydroxy-3,3′-5,5′-tetra-(tert.butyl)-diphenyl.
Preferred diphenol different from compounds of the formula (I) are diphenols of the formula (II)
wherein
A denotes C
1
-C
5
alkylene, C
2
-C
5
alkylidene, C
5
-C
6
cycloalkylidene, —O—, —SO—, —CO—, —S—, —SO
2
—, C
6
-C
12
arylene onto which further aromatic rings optionally containing heteroatoms may be condensed,
or a radical of the formula (IIa) or (IIb)
B in each case denotes C
1
-C
12
alkyl, preferably methyl, halogen, preferably chlorine and/or bromine
x in each case independently of one another is 0, 1 or 2,
p is 1 or 0, and
R
5
and R
6
, which may be chosen individually for each X
1
, independently of one another denote hydrogen or C
1
-C
6
alkyl, preferably hydrogen, methyl or ethyl,
X
1
denotes carbon, and
m is an integer from 4 to 7, preferably 4 or 5, with the proviso that at least one atom is X
1
and R
5
and R
6
are simultaneously alkyl.
Preferred compounds of the formula (II) are 2,2-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane and 1,3-bis[2-(4-hydroxyphenyl)-2-propyl]benzene, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 1,1-bis(4-hydroxyphenyl)cyclohexane, in particular 2,2-bis(4-hydroxyphenyl)propane (bisphenol A).
One compound of the formula (I) may be used with the formation of binary copolycarbonates, or also a plurality of compounds of the formula (I) may be used.
There may also be used one compound of the formula (II), with the formation of binary copolycarbonates, as well as a plurality of compounds of the formula (II).
The educts of the formulae (I) and (II) may obviously contain impurities resulting from the synthesis. A high degree of purity is however desirable and should be aimed for, and accordingly those educts having the highest possible purity are used.
According to DE-A 2 119 779 the production of polycarbonates is carried out under the participation of monomers of the formula (I) preferably in solution, and more specifically according to the phase boundary process and the homogeneous phase process.
Details of the production of polycarbonates according to the phase boundary process may be found for example in “Schnell”, Chemistry and Physics of Polycarbonates, Polymer Reviews, Vol. 9, Interscience Publishers, New York, London, Sydney 1964 and in Polymer Reviews, Volume 10, “Condensation Polymers by Interfacial and Solution Methods”, Paul W. Morgan, Interscience Publishers, New York, 1965, Chap. VIII, p. 325 and EP 971 790.
In addition polycarbonates may also be produced by the known melt production process (so-called melt transesterification process), which is described for example in DE-A 1 96 46 401 or in DE-A 1 42 38 123. In addition transesterification processes (acetate process and phenyl ester process) are described for example in U.S. Pat. Nos. 3,494,885, 4,386,186, 4,661,580, 4,680,371 and 4,680,372, in EP-A 26 120, 26 121, 26 684, 28 030, 39 845, 91 602, 97 970, 79 075, 146 887, 156 103, 234 913 and 240 301 as well as in DE-A 1 495 626 and 2 232 977.
The copolycarbonates according to the invention may contain various terminal groups. These are introduced by chain terminators. Chain terminators in the context of the invention are those of the formula (III)
wherein
R, R′ and R″ independently of one another may denote H, optionally branched C
1
-C
34
alkyl/cycloalkyl, C
7
-C
34
alkaryl or C
6
-C
34
aryl, for example butyl phenol, trityl phenol, cumyl phenol, phenol, octyl phenol, preferably butyl phenol or phenol.
The polycarbonates may contain minor amounts of 0.02 to 3.6 mole % (referred to the dihydroxy compound) of branching agents. Suitable branching agents are those compounds suitable fo

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