Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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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
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~ 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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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
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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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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.
EXAMPLE 1
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
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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.
EXAMPLE 2
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.
EXAMPLE 4
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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EXAMPLE 5
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.
COMPARATIVE EXAMPLE 1
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.
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