Note: Descriptions are shown in the official language in which they were submitted.
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Thermoplastic resin composition
The present invention relates to thermoplastic resin
compositions. More particularly, it relates to thermo-
plastic resin compositions having good physical properties,
particularly chemical resistance and falling ball impact
strength at welded part (hereinafter reerred to as ~Iweld
strength").
Polycarbonate resins have good physical properties,
particularly high impact resistance and good heat
resistance, and are known as "engineering plastics". It
is also known to blend various resins with polycarbonate
resins in order to enhance the physical properties of
polycarbonate resins in various ways. For instance, the
incorporati.on of diene rubber graft copolymers, such as
ABS resin (acrylonitrile-butadiene-styrene copolymer),
MBS resin (methyl methacrylate-butadiene-styrene copolymer)
or ABS~ resin (acrylonitrile-butadiene-styrene-methyl
~ethacrylate copolymer), into polycarbonate resins is
effective for improving moldability and for reducing the
thickness dependency of impact resistance (Japanese Patent
Publns. (examined) Nos. 15225/1963, 71/1964J 11496/1967
and 11142/1976). Further, the incorporation o~ ABS resin
into polycarbonate resins is effective for improving weld
streng~h (Japanese Patent Publn. (unexamined~ No.
99163/1976). However, the resistance of polycarbonates
and blended compositions to various chemicals including
gasoline, kerosene and brake fluid is so poor that serious
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problems occur when these materials are used in practice.
In addition, the weld strength of the materials is still
unsatisfactory.
As a result of an extensive study, it has now been
found that by blending a conjugated diene rubber-reinforced
styrene resin and a polyester elastomer into a polycarbon-
ate resin, in specific proportions, a thermoplastic resin
composition of enhanced chemical resistance and weld
strength can be provided.
According to this invention, there is provided a
thermoplastic resin composition which comprises (A) a
polycarbonate resin, (B) a conjugated diene rubber-
reinforced styrene resin and (C) a polyester elastomer r
optionally with a saturated polyester (D), the weight
proportion of the components (A), (B) and (C) or (C) ~ (D)
being from 5 - 90 : 5 - 90 : 2 - 60.
The polycarbonate resin (A) may be, for example, one
or more materials selected from aromatic polycarbonates,
aliphatic polycarbonates, aliphatic-aromatic polycarbon-
ates, etc. Normally, one or more of polymers and copoly-
mers of bisphenols e.g. 2,2-bis(4-hydroxyphenyl)alkanes,
bis(4-hydroxyphenyl)ethers, bis(4-hydroxyphenyl)sulfones,
bis(4-hydroxyphenyl)sulfides, bist4-hydroxyphenyl)sulfox-
ides, etc. are employed. Furthermore, the bisphenols may
be optionally substituted with one or more halogens on the
benzene ring(s). The preferred compounds are a homopolymer
of 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), a copoly-
mer of bisphenol A and a halogenated bisphenol A, a homo-
polymer of 2,2-bis(3,5 dimethyl-4-hydroxyphenyl)propane,
etc., and particularly a homopolymer of bisphenol A.
These polycarbonate resins and their methods of production
are described in various textboo~s and literature articles
including Encyclopedia of Polymer Science of TechnoLogy,
Vol. 10, pages 710 to 764 (1969). The molecular weight of
the polycarbonate resin (A) is not limited but, in general,
may be within the range of about 10,000 and 100,000,
q especially within the range of about 20,000 and 40,000.
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The conjugated diene rubber-reinforced styrene resin
~B) which may be used in the invention is obtainable by
the polymerization of one or more styrene monomers and
optionally other monomers in the presence of one or more
conjugated diene rubbers. Examples of the conjugated diene
rubbers are polybutadiene, styrene/butadiene copolymer,
butadiene-acrylonitrile copolymer, etc. These may be used
indiYidually or in combination. The styrene monomers
include styrene and its alkylated and/or halogenated
derivatives, and specific examples are styrenet alpha-
methylstyrene, p-methylstyrene, chlorostyrene, bromo-
styrene, etc. Examples of the other monomers are unsatur-
ated nitriles (e.g. acrylonitrile, methacrylonitrile,
fumaronitrile), acrylic or methacrylic esters (e.g. methyl
acrylate, ethyl acrylate, methyl methacrylate, hydroxyethyl
acrylate, glycidyl methacrylate), etc. These may also be
used individually or in combination. The contents of the
conjugated diene rubber(s), the styrene monomer(s~ and,
when used, the other monomer(s) which preferably consist
of unsaturated nitrile(s) and/or acrylic or methacrylic
ester(s), especially alkyl acrylate(s) or methacrylate(s),
in the conjugated diene rubber-reinforced styrene resin (B~
are favorably from about 5 to 80 % by weight, from about
10 to 60 % by weight, and from about 10 to 50 % by weight,
respectively. The conjugated diene rubber-reinforced
styrene resin (B) has a weight average particle size of
about 0.05 to 3 microns and a grafting rate (i.e. the per-
centage of the total weight of the monomer(s) grafted on
the rubber to the weight of the rubber) of about 20 to 150 %.
For the preparation of the conjugated diene rubber-
reinforced styrene resin (B), any conventional polymeriza-
tion procedure may be adopted such as emulsion polymeriza-
tion, suspension polymerization, bulk polymerization,
solution polymerization, emulsion-suspension polymerization
or bulk-suspension polymerization. During such polymeriza-
tion, it is usually to combine the entire amount o~ the
monomer~s) with the rubber to form a graft polymer, and
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some of the monomers combine with each other to form a
homopolymer or copolymer. The polymerization product is
thus a mixture comprising a graft polymer, a homopolymer
and a copolymer. Accordingly, the conjugated diene
S rubber-reinforced styrene resin (B) may be also prepared
by admixing a graft polymer having a high content of the
rubber with a styrene polymer (e.g. styrene-acrylonitrile
copolymer~ alpha-methylstyrene-acrylonitrile copoly~er)
previously and separately produced.
The polyester elastomer (C) may be a block polymer
which comprises a high melting point crystalline hard
segment consisting of an aromatic polyester, and a low
glass transition point soft segment consisting of an
aliphatic polyether or polyester. The aromatic p~lyester
forming the hard segment may be, for example, polyethylene
terephthalate, polybutylene terephthalate, polytetra-
methylene terephthalate, etc. The aliphatic polyether or
polyester forming the soft segment may be, for example,
polyether glycols (e.g. polyoxyethylene glycol, polyoxy-
methylene glycol, polyoxytetramethylene glycol), polymers
of epsilon-caprolactone, etc. The weight propor~ion of
the hard segment and the soft segment in the polyester
elastomer (C) is usually from about 20 : 80 to 95 : 5.
When desired, a portion of the polyester elastomer (C)
may be replaced by the saturated polyester (D). Examples
of the saturated polyester (D) are polyethylene tere-
phthalate, polytetramethylene terephthalate, polybutylene
terephthalate, etc. The amount of the saturated polyester
(D) is normally less than 50 ~ by weight, and pre~erably
less than 20 % by weight, of the combined amount of the
polyester elastomer (C) and the saturated polyester (D)~
As stated above, the thermoplastic resin composition
of the invention comprises a polycarbonate resin (A), a
conjugated diene rubber-reinforced styrene resin (B) and
a polyester elastomer ~C), optionally with a saturated
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polyester (D~, the contents of the components (A), (B) and
(C) or (C) ~ (D) being respectively from about 5 to 90 %,
from about 5 to 90 % by weight and from about 2 to 60 % by
weight; preferably from about 15 to 80 ~ by weight, from
about 15 to 80 % by weight and from about 5 to 50 ~ by
weight. When the content of the polycarbonate resin (A)
is less than about 5 ~ by weight, the heat resistance of
the thermoplastic resin composition is not good. When its
content is more than about 90 ~ by weight, the process-
ability is adversely affected. When the content of the
conjugated diene rubber-reinforced styrene resin (B) is
less than about 5 ~ by weight, the impact resistance and
the processability are inferior. When its content is more
than about 90 % by weight, the heat resistance is adversely
affected. When the content of the polyester elastomer
(C) or of the polyester elastomer (C) and the saturated
polyester tD) is less than 2 % by weight/ the chemical
resistance and the weld strength are lowered. When their
content is more than 60 % by weight, the weld strength is
also lowered.
For the preparation of the thermoplastic resin
composition of the invention, the essential and optional
components may be mixed together in any optional order.
Mixing may be achieved by the use of any conventional
mixing apparatus such as a Banbury (trade mark) mixer, a
monoaxial extruder or a biaxial extruder. If desired,
additivets) such as dyestuffs, pigments, stabilizers,
plasticizers, antistatic agents, ultraviolet absorbers,
flame retardants, lubricants and fillers may be
incorporated into the thermoplastic resin composition.
The thermoplastic resin composition of the invention
has various desirable physical properties. Particularly
notable is that it has much better heat resistance to
various chemicals, especially gasoline, kerosene and brake
fluid, and better weld strength than conventional blend
products of polycarbonate resins with ~BS resins. Accord-
1 ingly, it expands the field of application of polycarbonate
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resins and may be used for the manufacture of large parts
in automobiles.
Practical and presently preferred embodiments of the
invention are illustratively shown in the following
Examples wherein percentages and part(s) are by weight
unless otherwise indicated.
Example
Polycarbonate resin "Panlite L-1250" (trade mark,
comprising units of the formula:
CH
{~¢~~1~
CH3 O
; manufactured by Teijin Kasei) as the polycarbonate resin
(A), ABS resin "Kralastic MV (trade mark, manufactured by
Sumitomo Naugatuck) or ultra heat-resistant ABS resin
"Kuralastic KU-600" (trade mark, manufactured by Sumitomo
Naugatuck) as the conjugated diene rubber-reinforced
styrene resin (B), ester-ether type elastomer "Pelprene
P40H" (trade mark, manufactured by Toyobo) or ester-ester
type elastomer "Perprene S-3000" (trade mark, manufactured
by Toyobo) as the polyester elastomer and polybutylene
terephthalate "Tufpet N-1000" (trade mark, manufactured by
Toyobo) as the saturated polyester (D) were mixed together
by the aid of a ~ixer. The resultant mixture r having the
mixing proportions as shown in Table 1, was kneaded well
and extruded by the aid oE a monoaxial screw extruder to
~5 give a pelletized sample. From the thus obtained pellet-
ized sample, a test piece was prepared by injection
molding, and the test piece was subjected to measurement
of various physical constants.
The test results are shown in Table 1.
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Notes: 1) The tes~ piece (20 mm x 150 mm x 3 mm) was
prepared by press molding of the pellets of the thermo-
plastic resin composition. Onto one surface of the test
piece, gasoline, kerosene or brake fluid was applied, and
the test piece was stressed and allowed to stand with the
treated surface upward. Then, the distanc:e between the
maximum deflection point and the crack producing point, the
distance between the fixed edge and the maximum deflection
point and the maximum deflection amount were measured, and
the critical strain was calculated.
2) The thermoplastic resin composition in a molten
state (260C) was injected from two gates (2.5 mm x 2.0 mm
each) having a gate distance of 100 mm to make a test piece
(150 mm long, 150 mm wide, 3 mm high). The test piece was
placed on a cylinder of 120 mm in inner diameter, 126 mm in
outer diameter and 80 mm in height. A steel ball o~ 1 kg
was dropped onto the central part (the weld part) of the
test piece in a room kept at -30C, and the maximum energy
(kg.cm) which could be absorbed by the test piece without
breaking was measured.
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