CA1145092A - 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 olefinacrylate copolymer, and an acrylate copolymer. The compositions of the present invention are useful, for example, in the production of molded plastic articles.

Description

`` ~1 ~45~9Z 8cL-2ga3 The present invention relates to improving both ~he aged im-pact strength and the low temperature impac~ strength o high molecular weight, aromatic polycarbonate resins.

BAt~KGROUND OF THE INVENTION
5 ¦ It is well known that polycarbonate resins have high impact strength below a critical thickness of between about 1/2 an~ l/4 inches. Above this average thickness the impact strengt~ ~ poly-¦carbonate resins is low. Additionally, the impact strength of ~polycarbonate resins decreases rapidly as temper~tures dec~ea6e 10 ¦below about -5C and also after aging the polymers at elevated ¦temperature~ above about 100C. These characteristics consoquentl~
¦limit the fields of applications of these resins. ThU5, unmodifiec ¦polycarbonate materials are not practical for use at low or high ¦temperatures when good impact strength is required. T~erefore, it is desirable to improve both the impact strength of Po1yca~bonate resins at low and high temperatures and their aged impact strength i to thereby expand the fields of application of such re41n3.
DESCRIPTION OF THE INVENTION
l It has now been discovered that ternary compositio~s, whic~
20 ¦ comprise a high molecular weight, thermoplastic, aromatlc p~lycar-bonate, an acrylate copolymer and an olefin-acrylate cqpoly~er, exhibit not only improved aged impact strength, but ce~tain for~u-lations thereof also exhibit improved impact strength ~ both low l and high temperatures when compared to unmodified polycarbonate 25 ~ resins. These~novel compositions also exhibit good weld-line strengt~ .
High molecular weight, thermoplas~ic, aromatic polycarbo~a~es in the sense of the present invention are to be understoqd as homo-polycarbonates and copolycarbonates and mixtures thereo~ which hav average molecular weights of about 8,000 to more than 200,000, preferably of about 20,000 to 80,000 and an I.V. of 0.4~ to 1.0 ~ .

~ 145~9Z 8CL-20~3 dl/g as measured in methylene chloride at 25C. These polycarbon-ates ~re 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)hep-tane, 2~2-(3~5~3l`~57-tetrachloro-4~4~-dihydroxyphenyl)propan~r

2,2-(3,5,3',5'-tetrabromo-4,4'-dihydroxydiphenyl)propane, an~ (3,3'- .
dichloro-4,4'-dihydroxydiphenyl)methane. Other dihydric phenols which are also suitable for use in the preparation of the ab~ve polycarbonates are disclosed in U.S. Pat. Nos. 2,999,8351 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 litera~ure and U.S. Pat. Nos.

4,018,750 and 4,123,436, or by transesterifica~ion processes such ~ as are disclosed in UOS~ Pat. No. 3,153,008, as well as other i processes known to those skilled ln the art.
The aromatic polycarbonates utilized in the present lnvention also include the polymeric derivates of a dihydric phenol, a di-carboxylic 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 wlth hydroxy or acid terminated polyester, or with a dibasic acid in the¦
event a carbonate copolymer or interpolymer rather than a homopoly-¦
mer is desired for use in the preparation of the aromatic polycar- ¦
¦bonate utilized in the practice of this invention. Also employe~
~in the practice of this invention can be hlends of any of the above ¦materials to provide the aromatic polycarbonate.

30 ~ Branched polycarbonates, such as are described in ~.S. Pat.

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1145~9Z 8CL- 2 9 8 3 No. 4,001,184, can also be utilized in the practice of thi~ inven-tion, as can blends of a linear polycarbonate and a branche~ poly~
carbonate.
The "acxyla~e" copolymer utilized in the present inve~tlon is a copolymer of a Cl-C5 methacrylate and a Cl-C5 acrylate, wherein the term "Cl-Cs" represents both saturated and unsaturated, straight or branched chained aliphatic hydrocarbon radical~ 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 di~cxylate, n-butyl acrylate, and 1,3-butylene diacrylate. Preferred ~ethac~y-lates for use in this copolymer include methyl me~hacrylate, iso-butyl methacrylate, 1,3-butylene dimethacrylate, butyl metha~rylat and ethyl methacrylate.
The acrylate portion of the copol~mer, based on the total weight of the copolymer can range from about 50 to abou' 35 weight percent. The methacrylate portion of the copolymer can rang~ 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 defined above, can be pre- ¦
pàred by methods well known to those skilled in the art or can be obtained commercially. For example, Rohm and Haas' Acryloid~ XM
330 copolymer, which is a copolymer of n-butyl acrylate and ~ethyl methacrylate, is suitable for use in the present invention The "olefin-acrylate" copolymer utilized in the present ln~en-tion is a copolymer of a C2-C5 olefin and a Cl-C5 acrylate. T~e term "Cl-C5" is as defined above, and the term "C2-Cs" represents a _ ~

5~9Z scL-2sa3 straight or branched chain aliphatic hydrocarbon radical having from 2 to 5 carbon atoms. The preferred olefins are ethyle~e, propylene and isobutylene. Preferred acrylates which are utilized in the olefin-acrylate copolymer are ethyl acrylate, n-butyl acry-S late, 1,3-butylene diacrylate, methyl acrylate, 1,4-butanedlol di-acrylate and isobutyl acrylate.
The acrylate por~ion of the olefin-acrylate copolymer, ~ased on the total weight of the copolymer, can range from about 10 to about 30 weight percent. The olefin portion of the copolyme~ ca~
lQ range from about 70 to about 90 weight percent.
The preferred olefin-acrylate copolymer for use in this inven tion is an ethylene-ethyl acrylate copolymer, in which the weight ¦
ratio of the ethylene fraction to the ethyI acrylate fraction is about 4.5 to 1.
15 ¦ Suitable olefin-acrylate copolymers, as defined above, can be ;Iprepared by methods well known to those skilled in the art o~ can !Ibe obtained commercially. For example, Union Carbide's ~akellte~
¦¦DPD-6169 ethylenq-ethyl acrylate copolymer is suitable fo~ use in ¦¦the present invention.
20¦ The amount of the olefin-acrylate copolymer present $n the ternary composition of the present invention can range ~rom about O.S to about 4 parts, by weight, per hundred parts of the aromatic polycarbonate. Preferably, the olefin-acrylate copolyme~ is present jin amounts of from about 1 to about 3 parts, by weight, per hun- ¦
~5 ¦ dred parts of ~he aromatic polycarbonate. The amount of the acry-i làte copolymer present in the ternary composition can va~y romabout 2 to about 6 parts, by weight, per hundred parts o~ the aro-¦
!jmatic polycarbonate. Preferably, the acrylate copolymer is present !¦ in amounts of from about 3 to about 5 parts, by weight, pe~ hundred 30 ~! parts of the aromatic polycarbonate.
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I i _ . _. _ _ , ... . . . . . _ _ _ ~ 509~ 8CL-2993 It is also regarded to be among the features of thig i~vention to include in the ternary polycarbonate composition conventional additives for purposes such as reinforcing, coloring or stabllizin the composition in conventional amounts.
The compositions of the invention are prepared by mechanica~ly blending, the high molecular weight aromati'c polycarbonate wlth the olefin-acrylate copolymer and the acrylate copolymer by convention-al methods.
EXAMPLES
The following examples are set forth to illustrate the inven-tion and are not to be construed to limit the scope of the ipven-tion. In the examples and comparative studies, all part~ and per-centages are on a weight basis unless otherwise specified.

Ninety-five (95) parts of an aromatic polycarbonate, derived from 2,2-bist4-hydroxyphenyl)propane and having an intrinsic vis-cosity (I.V.) in the range of from about 0.46 to about 0,49 dl/g as detexmined in methylene chloride solution at 25C, was mixed ~ wit~ four (4) parts of a copolymer of n-butyl acrylate an~ ~ethyl 20 Imethacrylate (hereinafter copolymer A), said copolymer having a jweight ratio of n-butyl-acrylate to methyl,methacrylate o~ a~out 13 to 2, and one (1) part of an ethylene-ethyl acrylate copolymer ¦(hereinafter referred to as copolymer B), said copolymer having a ~Iweight ratio of ethylene to ethyl acrylate of about 4.5 to 1. T~e 25 l¦ingredients were then blended together by mechanically mixing the~
¦in a laboratory tumbler and the resulting mixture was fed to an ¦,extruder which was operated at about 265C. The resulting extru-~Idate was comminuted into pellets. The pellets were injectior~moldec ¦jat about 290C to 310C into test specimens of about 5" by 1~2" by 30 ¦~1/4" and 5" by 1/2" by 1/8", the latter dimension being the specimen l14509Z 8CL-2983 thickness. Izod impact strengths of these specimens are measured according to the notched Izod test, ASTM D256, and are set forth in Table I. The ductile-brittle transition temperature (D/B), which is the highest temperature at which a sample begins to ex-hibit a brittle mode of failure rather than a ductile mode offailure, was obtained according to the procedures of ASTM D256 and is also listed in Table I. The sample labeled CONTROL was ohtained from a polycarbonate resin having an I.V. from about 0.46 to about .
0.49 dl/g and was prepared without either copolymer A or cop~lymer B.

The procedure of Example 1 was repeated exactly, except that the weight parts of polycarbonate, copolymer A and copolymer B in l the test specimen were, respectively, 96, 3 and 1. The results of 15 1 the notched Izod impact tests and the D/B are listed in Table I.

i EXAMPLE 3 The procedure of Example 1 was repeated exactly, except that the weight parts of polycarbonate, copolymer A and copolymer B in ~the test specimens were, respectively, 96, 2 and 2. The results of~
~0 the notched Izod impact tests are listed in Table I.

The procedure of Example 1 was repeated exactly, except that the weight parts of polycarbonate, copolymer A and copolymer B in I the test specimens were, respectively, 94, 4 and 2. The results of 25 ¦Ithe notched Iz~d impact tests are listed in Table I.

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The procedure of Example l was followed exactly, and tho re-sulting composition, which contained 95 weight parts polycarbonate, 4 weight parts copolymer A, and l weight part copolymer B, was tested, using the notched Izod test, for subzero temperature impact erformance of l/8" thick samples which were each maintained at -18C, -29C and -34C for 45 minutes.
The results of these tests, as expressed in f~. lb./in., are set forth in Table II. The results of these tests illustrate the excellent low temperature impact strength of the invention' 5 ter-nary composition.

The procedure of Example l was followed except that copolymer B was not added to the mixture. The resulting composition, which contained 96 weight parts polycarbonate and 4 weight parts copoly-l mer A, was tested for subzero temperature impact performance of a ;ll/8" thick sample at -18C and -29C. The result of these tests ¦¦are set forth in Table II.

. TABLE I I
20 1, Impact Strength, ft. lb.~in, l/8" Thick at Composition of: -18C -29C -34C
Example 6 9.9 5.7 5.3 ¦Comparative Example l 4.0 2.6 *
25 1* Test not made.
The invention's ternary compositions also exhibited good weld-line strength as shown in double gate Izod impact tests which were conducted to procedures as specified in ASTM D256.

'! 8 i! I

Claims (8)

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, from about 2 to about 6 parts by weight per hundred parts of said aromatic polycarbonate of copolymer A, which is a copolymer of a C1-C5 acrylate and a C1-C5 methacrylate, and from about 0.5 to about 4 parts by weight per hundred parts of said aromatic polycarbonate of copolymer B, which is a copolymer of a C2-C5 olefin and a C1-C5acrylate, the weight ratio of acrylate:methacrylate in copolymer A being in the range of about 50-85:-15-50 and the weight ratio of olefin:acrylate in copolymer B being in the range of about 70-90:10-30.

2. The composition of claim 1, wherein copolymer A is present in an amount of from about 3 to about 5 parts by weight per hundred parts of aromatic polycarbonate .

3. The composition of claim 1, wherein copolymer B is present in an amount of from about 1 to about 3 parts by weight per hundred parts of aromatic polycarbonate.

4. The composition of claim 1, wherein in copolymer B, the olefin is selected from the group consisting of ethylene, propylene, isobutylene and the acrylate is selected from the group consisting of ethyl acrylate, n-butyl acrylate, 1,3-butylene diacrylate, isobutyl acrylate, 1,4-butanediol diacrylate and methyl acrylate and, in copolymer A, 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.

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

6. The composition of claim 5, wherein in copolymer B, the olefin is ethylene and the acrylate is ethyl acrylate and, in copolymer A, the methacrylate is methyl methacrylate and the acrylate is n-butyl acrylate.

7. The composition of claim 6, wherein the weight ratio of ethylene to ethyl acrylate in copolymer A ranges from about 4/1 to about 6/1 and, in copolymer B, the weight ratio of methyl methacrylate to n-butyl acrylate ranges from about 1/2 to about 2/1.

8. 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 1 to about 3 parts by weight per hundred parts of said aromatic polycarbonate, of a copolymer of ethylene and ethyl acrylate, wherein the weight ratio of ethylene to ethyl acrylate is about 4.5/1 and from about 3 to about 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.