CA1145091A - Polycarbonate compositions - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

The present invention is concerned with ternary polycarbonate compositions having improved impact strength.
The ternary compositions comprise a mixture of thermoplastic, aromatic polycarbonates which are derived from aromatic, dihydroxy compounds, an acrylate copolymer, and an organic silicone compound. These novel compositions are useful, interalia, in the manufacture of molded plastic articles.

Description

~5~g~ 8CL-3028 The present invention relates to improving both the aged impact strength and the low temperature impact strength of high molecular weight, aromatic polycarbonate resins.
sAcKGRouND OE THE INVENTION
It is well known that polycarbonate resins have high impact strength below a critical thickness of between about 1/2 and 1/4 inches. Above this average thickness the impact strength of polycarbonate resins is low. Additionally, the impact strength of polycarbonate resins decreases rapidly as temperatures decrease below about -5C and also after aging the polymers at elevated temperatures above about 100C. These characteristics consequently limit the fields of applications of these resins.
Thus, unmodified polycarbonate materials are not practical for use at low or high temperatures when good impact strength is required. Therefore, it is desirable to improve both the impact strength of polycarbonate resins at low and high temperatures and their aged impact strength to thereby expand the fields of application of such resins.
DESCRIPTION OF THE INVENTION
-It has now been discovered that ternary compositions, which comprise a high molecular weight, thermoplastic, aromatic poly-carbonate, an acrylate copolymer and an organic silicone compound exhibit not only improved aged impact strength, but certain formulations thereof also exhibit improved impact strength at both low and high temperatures when compared to unmodified polycarbonate resins. These novel compositions also exhibit good weld-line strength.
High molecular weight, thermoplastic, aromatic polycarbonates in the sense of the present invention are to be understood as homopolycarbonates and copolycarbonates and mixtures thereof which have average molecular weights of about 8,000 to more than 200,000, .~ -- 1 --.
~' ~ 5~ 8CL-3028 preferably of about 20,000 to 80,000 and an I.V. of 0.40 to 1.0 dl/g as measured in methylene chloride at 25C. These polycarbonates are derived from dihydric phenols such as, for example, 2,2-bis(4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)-methane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 4,4-bis(4-hydroxyphenyl)heptane, 2,2-(3,5,3',5' tetrachloro-4,4'-dihydroxyphenyl)propane, 2,2-(3,5,3',5'-tetrabromo-4,4'-dihydroxydiphenyl)propane, and (3,3'-dichloro-4,4'-dihydroxy-diphenyl)methane. Other dihydric phenols which are also suitable for use in the preparation of the above polycarbonates are disclosed in U.S. Pat. Nos. 2,999,835, 3,028,365, 3,334,154, and 4,131,575.
These aromatic polycarbonates can be manufactured by known processes, such as, for example, by reacting a dihydric phenol with a carbonate precursor such as phosgene in accordance with methods set forth in the above-cited literature and U.S. Pat. Nos.
4,018,750 and 4,123,436, or by transesterification processes such as are disclosed in U.S. Pat. No. 3,153,008, as well as other processes known to those skilled in the art.
The aromatic polycarbonates utilized in the present invention also include the polymeric derivates of a dihydric phenol, a dicarboxylic acid, and carbonic acid, such as are disclosed in U.S. Pat. No. 3,169,131.
It is also possible to employ two or more different dihydric phenols or a copolymer of a dihydric phenol with a glycol or with hydroxy or acid terminated polyester, or with a dibasic acid in the event a carbonate copolymer or inter-polymer rather than a homopolymer is desired for use in the preparation of the aromatic polycarbonate utilized in the practice of this invention. Also employed in the practice of this invention can be blends of any of the above materials to provide the aromatic polycarbonate.

- 2 -~ 8CL-3028 ¦ Branched polycarbonates, such as are described in U.S. Pat.
No. 4,001,184, can also be utilized in the practice of this inven-tion, as can blends of a linear polycarbonate and a branched poly-carbonate.
The "acrylate`' copolymer utilized in the present invention is a copolymer of a Cl-Cs methacrylate and a Cl-C5 acrylate, wherein the term "Cl-Cs'` represen~s both saturat~d a~d unsaturated, straight or branched chained aliphatic hydrocarbon radicals having from 1 to 5 carbon atoms.
Preferred acrylates for use in the copolymer are methyl acry-late, ethyl acrylate, isobutyl acrylate, 1,4-butanediol diacrylate, n-butyl acrylate, and 1,3-butylene diacrylate. Preferred methacry-lates for use in this copolymer include methyl methacrylate, iso-butyl methacrylate, 1,3-butylene dimethaarylate, butyl methacrylat~
and ethyl methacrylate.
The acrylate portion of the copolymer, based on the total weight of the copolymer can range from about 50 to about 85 weight i percent. The methacrylate portion of the copolymer can range from ¦¦about 15 to about 50 weight percent.
The preferred acrylate copolymer for use in this invention is a copolymer of n-butyl acrylate and methyl methacrylate in which the weight ratio of the n-butyl acrylate fraction to the methyl methacrylate fraction in the copolymer is about 3 to 2.
Suitable acrylate copolymers, as de~ined above, can be pre-2~ pared by methods well known to those skilled in the art or can be ¦
obtained commercially. For example, Rohm and Haas' Acryloid~ KM
330 copolymer, which is a copolymer of n-butyl acrylate and methyl methacrylate, is suitable for use in the present invention.
! Organic silicone compounds suitable for use in this invention 30 1¦ include, for example, silicone ~luids such as phenyl dimethyl i~ - 3 -!l ~ _ .. I

! I
~ 5~ CL-3028 polysiloxane silicone fluid and methyl hydrogen silicone fluid, and other organic silicone compounds, such as, for example, silane type coupling agents such as-diphenyl silane diol. Other organic silicone compounds suitable for use herein will be apparent to thos skilled in the art. The preferred orga~ic silicone compounds for use herein are silicone fluids, especially phenyl dimethyl polysi-loxane and methyl hydrogen silicone fluids. The preferred organic silicone compound for low temperature appl-ications is phenyl di-methyl polysiloxane silicone fluid. The organic silicone compound suitable for use herein are available co~mercially.
The amount of organic silicone compound present in the ternar composition of the present invention can range from about 0.04 to about 2.5 parts, by weight, p-er hundred parts of the aromatic poly carbonate. Preferably, the organic silicone compound is present in amounts of from about 0.05 to about 2 parts, by weight, per hun-jdred parts of thè aromatic polycarbonate. The amount of the acry-¦late copolymer present in the ternary co~position can vary from about 2 to about 6 parts, by weight, per hundred parts of the aro~ ¦
!!matic polycarbonate. Preferably, the acrylate copolymer is present;
20 ¦lin amounts of from about 3 to about 5 parts, by weight, per hundred parts of the aromatic polycarbonate.
It is also regarded to be among the features of this invention;
to include in the ternary polycarbonate composition conventional additives for purposes such as reinforcing, coloring or stabilizing Ithe composition in conventional amounts.
` The compositions of the invention a~e prepared by mechanically blending the high molecular weight aroma~ic polycarbonate with the organic silicone compound and the acrylate copolymer by conven-¦Itional methods.

i! I
1'1 .
Ii - 4 ~
~!
!

~ S~9~ 8CL-3028 EXAMPLES
The following examples are set forth to illustrate the inven-tion and are not to be construed to lim~t the scope of the inven-tion. In the examples, all parts and porcentages are on a weight basis unless otherwise specified.

Ninety-four and one half (94.5) parts of an aromatic polycar-bonate, derived from 2,2-bis~4-hydroxyphenyl)propane and having an intrinsic viscosity (I.V.) in the range of from about 0.46 to abou~
0.49 dl/g as determined in methylene ch~orlde solution at 25C, was mixed with four (4) parts of a copolyme~ of n-butyl acrylate and methyl methacrylate (hereinafter acrylate copolymer), said copoly-mer having a weight ratio of n-butyl-ac~ylate to methyl methacry-l late of about 3 to 2, and one and one half (1.5) parts of phenyl 15 ¦ dimethyl polysiloxane silicone fluid (hereinafter referred to as PDP). The ingredients were then blended together by mechanically ¦
mixing them in a laboratory tumbler and the resulting mixture was I
i¦fed to an extruder which was operated at about 265C. The result-¦
¦¦ing extrudate was comminuted into pellets. The pellets were in-20 ~~jection molded at about 290C to 310C ~nto test specimens of i about 5" by 1/2" by 1/4" and 5" by 1/2" by 1/8", ~he latter dimen-i sion being the specimen thickness. Izo~ impact strengths of these specimens are measured according to the notched Izod test, ASTM
D256, and are set forth in Table I. The ductile~~rittle transitio7 ~5 ! temperature (D/B), which is the highest temperature at which a . sample begins to exhibit a brittle mode of fai~ure rather than a !Iductile mode of failure, was obtained according to the procedures ¦lof ASTM D256 and is also listed in Table I. The sample labeled '~CONTROL was obtained from a polycarbonate resin having an I.V. from 30 ',labout`0.46 to about 0.49 dl/g and was prepared without either the ¦
~ljacrylate copoly~er or an organic sllico~e compound.

,l ., ~

The procedure of Example 1 was repeated exactly, except that the weight of polycarbonate, acrylate copolymer and PDP in the test specimen were, respectively, 95, 4 and 1. The results of the notched Izod impact tests are listed in Table I.

The procedure of Example 1 was repeated exactly, except that PDP was replaced with methyl hydrogen silicone fluid (MHSF). The weight parts of polycarbonate, acrylate copolymer and MHSF in the test specimen were, respectively, 95.9, 4 and 0.1. The results of the notched Izod impact tests are listed in Table I.

The procedure of Example 3 was repeated exactly, except that the weight parts of polycarbonate, the acrylate copolymer and MHSF in the test specimen were, respectively, 95.95, 4 and 0.05. The results of the notched Izod impact tests are listed in Table I.

~S~

U~
m ~` ~ , .
~:
_, .

C~
. O
U~ _ _ s . ~
co ~1 d' ~ ~ ~ .
s ~ U~ _ _ _ . ,~, r~
~: s U . ' ~`
o CO
E~ ~ ~ * ~
: ~ ~1 ~ ~ ~ ~ d . ~ æ
.,, .
X~ . ~ ~ .
rl Q~ _ S ~ o r~
E~ . . . .. o ~ O
O ~P o . ~ o ~ ~ ~ ~ ~ o ~ ~
Z S S~ o

3 3 J.l u.~ rd ~ O l~d O , ~ 4 ~ . . u~ u~ 0 4~
o a) a) ~ ~ o ~J ` Q~ Q. ~ ~ a) u~ ~ ~ ~ ~ O ~ ~ ~ ~ O
~0 'X X XX' Z, lc U ~ *

~45~9~ 8CL-3028 The invention's ternary compositions also exhibited good weldline strength as shown in double gate Izod impact tests which were conducted to procedures as specified in ASTM D256.

Claims (9)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A ternary polycarbonate composition comprising in admixture, a high molecular weight aromatic polycarbonate which is based on a dihydric phenol, an acrylate copolymer, which is a copolymer of a C1-C5 acrylate and a C1-C5 methacrylate in an amount of about 2 to about 5 parts by weight per hundred parts of aromatic polycarbonate, and a minor amount of organic silicone compound.

2. The composition of claim 1, wherein the organic silicone compound is a silicone fluid.

3. The composition of claim 1, wherein the organic silicone compound is present in an amount of from about 0.04 to about 2.5 parts by weight per hundred parts of aromatic polycarbonate.

4. The composition of claim 3, wherein the organic silicone compound is present in an amount of from about 0.05 to about 2 parts by weight per hundred parts of aromatic polycarbonate.

5. The composition of claim 2, wherein the silicone fluid is selected from the group consisting of phenyl dimethyl polysiloxane silicone fluid and methyl hydrogen silicone fluid and, in the acrylate methacrylate copolymer, the methacrylate is selected from the group consisting of methyl methacrylate, 1,3 butylene dimethacrylate, isobutyl methacrylate, butyl methacrylate and ethyl methacrylate and the acrylate is selected from the group consisting of 1,4-butanediol diacrylate, isobutyl acrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate and 1,3-butylene diacrylate.

6. The composition of claim 5, wherein the aromatic polycarbonate is derived from 2,2-bis(4-hydroxy-phenyl)propane.

7. The composition of claim 6, wherein in the acrylate-methacrylate copolymer, the methacrylate is methyl methacrylate and the acrylate is n-butyl acrylate.

8. The composition of claim 7, wherein in the acrylate-methacrylate copolymer, the weight ratio of methyl methacrylate to n-butyl acrylate ranges from about 1/2 to about 2/1.

9. A ternary polycarbonate composition comprising in admixture a high molecular weight aromatic polycarbonate which is derived from 2,2-bis(4-hydroxyphenyl)-propane and from about 0.05 to about 2 parts by weight, per hundred parts of said aromatic polycarbonate, of a silicone fluid and from about 2 to aobut 5 parts by weight, per hundred parts of said aromatic polycarbonate, of a copolymer of methyl methacrylate and n-butyl acrylate, wherein the weight ratio of n-butylacrylate to methyl methacrylate is about 3/2.