Note: Descriptions are shown in the official language in which they were submitted.
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POLYPHENYLENE OXIDE RESIN COMPOSITIONS
G
BACKGROUND OF THE INVENTION
(Field of the Invention)
This invention relates to polyphenylene oxide
resin compositions having excellent heat distortion
resistance, moldability, impact resistance and
resistance to chemicals.
(Description of the Prior Art)
Polyphenylene oxide resins are resins having
excellent heat resistance, hot water resistance,
dimensional stability, resistance to chemicals,
mechanical properties, electrical properties and the
like. However, because of their high melt viscosity,
they have a poor moldability, in addition to which
their impact resistance is not sufficiently large.
Hence, although methods are known for blending in
different types of polymeric materials such as
polystyrene resins, even if polystyrene resins are
blended in the impact resistance cannot be sufficiently
improved, moreover, doing this tends to compromise the
excellent properties of polyphenylene oxide resins,
such as their heat resistance and resistance to
chemicals. In addition, methods are known that involve
the blending in of polystyrene resins modified with
butaduene rubber or EPDM, or styrene-based
thermoplastic elastomers. Although these are effective
for improving the impact resistance and there is little
descrease in the resistance to chemicals, the increase
in the melt viscosity is pronounced, as a result of
which the moldability and the appearance of the molded
articles are greatly compromised. Hence, these cannot
be regarded as methods that are widely employable.
A method whereby an ethylene-unsaturated
carboxylic acid ester copolymer is additionally blended
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was proposed in ,Tapanese published unexamined patent
application [Kokai] No.5,8-17,142(1983) in order to
improve upon the drav~backs due to the above-described
styrene resin blending. It was indicated there that
this exhibits excellent~~effects on enhancing the
moldability, impact resistance and resistance to
chemicals. However, because this method has the
drawback that peeling arises in the molded product when
the above-mentioned ethylene copolymer is added to an
excessive degree, strict control of the amount of
addition is necessary.
SUr~MARY OF THE INVENTION
The inventors therefore conducted intensive
studies in order to find additives which have addition
effects comparable to or better than those of the
above-mentioned copolymers, and which can also be added
in a large amount, thereby enabling even further
improvement in the moldability, impact resistance,
surf ace appearance and other properties. As a result,
it was found that the desired improvement can be
achieved by using the ethylene copolymers described
below. Hence, the object of the present invention is
to provide polyphenylene oxide resin compositions which
have various excellent properties, such as heat
resistance, moldability, impact resistance, resistance
to chemiclas, and surf ace appearance.
According to the present invention, there is
provided a polyphenylene oxide resin composition
comprising 90-99.9 parts by weight of polyphenylene
oxide resin or a polymer ingredient containing
polyphenylene oxide, and 0.1-10 parts by weight of an
ethylene-carbon monoxide-(meth)acrylic acid ester
copolymer.
By means of the present invention, the moldability
and impact resistance are both improved at the same '
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time, polyphenylene oxide resins having excellent
physical properties are obtained, and use can be made
of these in a broad range of applications as high-
performance engineering plastics.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The polyphenylene oxide used in the present
invention is a polymer obtained by the oxidative
polymerization of one or more phenol compounds having
the general formula
OH
R5 ~. R1
R4 ~ R2
R3
(where R1, R2, R3, R4 and R5 are selected from hydrogen,
halogen atoms, hydrocarbon groups or substituted
hydrocarbon groups, with at least one of these being a
hydrogen atom) with oxygen or an oxygen-containing gas,
and using an oxidative coupling catalyst.
Specific examples that can be cited of R1, R2, R3,
R4 and R5 in the above general formula include
hydrogen, chlorine, bromine, fluorine, iodine, methyl,
ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, tert-
butyl, chloroethyl, hydroxyethyl, phenylethyl, benzyl,
hydroxymethyl, carboxyethyl, methoxycarbonylethyl,
cyanoethyl, phenyl, chlorophenyl, methylphenyl,
dimethylphenyl, ethylphenyl and allyl.
Specific examples that may be cited of phenol
compounds having the above general formula include
phenol, o-, m- and p-cresol, 2,6-,2,5-,2,4- and 3,5-
' dimethylphenol, 2-methyl-6-phenylphenol, 2,6-
diphenylphenol, 2,6-diethylphenol, 2-methyl-6-
ethylphenol, 2,3,5-, 2,3,6- and 2,4,6-trimethylphenol,
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3-methyl-6-t-butylphenal, thymol and 2-methyl-6-
allylphenol.
In cases where the polyphenylene oxide resin is
produced by the oxidative polymerization of these
phenols, this may also consist of copolymerization
between a phenol compound having the above general
formula and a phenol compound other than those having
the above-described general formula, such as a
polyhydroxy aromatic compound, examples of which
include bisphenol A, tetrabromobisphenol A, resorcinol,
hydroquinone, and novolak resins.
Preferable examples that may be cited of the
polymer thus obtained, (that is, of the polyphenylene
oxide resin), include homopolymers of 2,6-
dimethylphenol or 2,6-diphenylphenol, and copolymers of
a large amount of 2,6-xylenol and a small amount of 3-
methyl-6-t-butylphenol or 2,3,6-trimethylphenol.
The polyphenylene oxide resin may also be obtained
by the graft modification of other polymers onto the
above-described homopolymer or copolymer. Examples
that may be cited include resins obtained by the
oxidative polymerization of the above-mentioned phenols
in the presence of EPDM, resins obtained by the
oxidative polymerization of the above-mentioned phenols
in the presence of a polystyrene resin, resins obtained
by the graft polymerization of styrene and/or other
vinyl monomers using a radical initiator in the
presence of a homopolymer or a copolymer of the above-
mentioned phenols, and resins obtained by melt-kneading
and reacting a homopolymer or a copolymer of the above-
mentioned phenols with a polystyrene resin in the
presence of a radical generator. Of these, a resin
obtained by modification with a polystyrene resin is
preferable.
The polyphenylene oxide resin may be a resin '
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obtained by modifying a homopolymer or copolymer of the
above-mentioned phenols with a modifying agent such as
a polyfunctional compound.
The polyphenylene oxide resin may be used together
t
5 with other polymer ingredients. Other polymer
ingredients such as this that may be cited include
polystyrene resins, polyolefins, polyesters,
polycarbonates, polyamides, polyacetals, polyvinyl
chlorides and synthetic rubbers. Of these, the use of
polystyrene resins is especially preferable.
The term "polystyrene resin" here signifies a
homopolymer or copolymer of a vinyl aromatic compound.
More specific examples that may be cited are resins
containing at least 25 wt~ of styrene or a derivative
thereof, such as a -Methylstyrene or vinyltoluene.
Specific examples of these polystyrene resin's include,
as mentioned above, homopolymers of styrene or
derivatives thereof, and styrene polymers modified by
the mixture or interaction of natural or synthetic
elastomer substances such as polybutadiene,
polyisoprene, butyl rubbers, EPDM rubbers, ethylene-
propylene copolymers, natural rubbers, polysulfide
rubbers, polyurethane rubbers and epichlorohydrin
rubbers, and styrene-containing copolymers, examples of
which include styrene-based thermoplastic elastomers
such as styrene-acrylonitrile copolymers (SAN),
styrene-butadiene copolymers, styrene-malefic anhydride
copolymers, styrene-acrylonitrile-butadiene polymers
(ABS), poly- a -methyl-styrene, styrene-butadiene-
styrene block copolymers and styrene-isobutylene-
styrene block copolymers, or styrene-based
thermoplastic elastomers obtained by the hydrogenation
of the diene rubber center blocks therein. Resins that
are even more preferable for the present invention are
polystyrene homopolymer, and rubber-modified
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polystyrenes obtained by polymerizing styrene in the
presence of 3-30 wt~, and preferably 4-12 wt~, of
polybutadiene rubber or EPDM rubber.
The above-described EPDM rubber is a rubbery
interpolymer composed of a mixture of monoolefins and
polyenes; this includes resins produced from ethylene,
a -olefins and polyenes. Preferable rubbery
interpolymers are those which are composed of 10-90
mold of ethylene, 10-90 mold of ce-olefins having 3-16
carbons, and 0.1-12 mold of non-conjugated cyclic or
chain-like dienes having 5-20 carbons. Especially
preferable types of rubbery interpolymers are those
interpolymers composed of ethylene and C~-olefins
having 3-10 carbons, and especially propylene, non-
conjugated cyclic or chain-like dienes having 5-10
carbons, examples of which include 5-ethylidene-2-
norbornene, dicyclopentadiene and 1,4-hexadiene.
In cases where a modified resin is used as the
polyphenylene oxide resin, or where this is used
together with another polymer ingredient, it is
preferable for the resin employed to have a composition
in which the phenol polymer or copolymer units are used
in an amount of at least I5 parts by weight, preferably
15-90 parts by weight, and even more preferably 30-70
parts by weight, and the modifying ingredients or other
polymer ingredients are used in an amount of no more
than 85 parts by weight, preferably 10-85 parts by
weight, and even more preferably 30-70 parts by weight.
In the present invention, 0.1-10 parts by weight,
and preferably 0.5-5 parts by weight, of an ethylene-
carbon monoxide-(meth)acrylic acid ester copolymer is
blended in per 90-99.9 parts by weight of this type of
polyphenylene oxide resin or, when polyphenylene oxide
is used as a modified resin or is used together with
other polymer ingredients, per 90-99.9 parts by weight d
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of the combined amount of polyphenylene oxide and the
other polymers. The reference here to "(meth)acrylic
acid ester" means an acrylic acid ester or a
methacrylic acid ester. When the above-mentioned
ethylene copolymer is blended in a small amount, the
addition effects are inadequate, on the other hand,
when the amount blended in is too large, the decrease
in the mechanical properties of the molded product, and
especially the rigidity, becomes too great, in addition
to which layer-like peeling at the surf ace of the
molded product readily occurs, which is undesirable.
The carbon monoxide polymerization units in this
copolymer are included in a ratio of 1-30 wt~ and
preferably 2-20 wt~, and the (meth)acrylic acid ester
polymerization units are included in a ratio of 3-50
wt~, and preferably 10-40 wt~. When a copolymer that
does not contain carbon monoxide, such as an ethylene-
(meth)acrylic acid ester copolymer, is used as the
modifier for the polyphenylene oxide resin and is
blended in a large amount, the physical properties such
as the impact resistance instead decrease, and the
desired improvements in the properties are not
achieved.
The (meth)acrylic acid esters may be, for example,
the approximately 1- to 10-carbon alkyl esters of
acrlylic acid or methacrylic acid. Specific examples
of these include methyl acrylate, ethyl acrylate,
isopropyle acrylate, isobutyl acrylate, n-butyl
acrylate, 2-ethylhexyl acrylate, methyl methacrylate,
isobutyl methacrylate and n-butyl methacrylate. Of
these, the use of 1- to 4-carbon alkyl esters of
acrylic acid or methacrylic acid is preferable.
It is preferable to use as this copolymer one that
has a melt flow rate, at 190C and under a load of 2160
g, of 0.1-400 g/10 minutes, and preferably 1-100 g/10
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minutes. In cases where a copolymer having a melt flow
rate of less than 0.1 g110 minutes is used, the
dispersion with polyphenylene oxide resin becomes
inadequate and it becomes difficult to fully elicit the
blending effects. On the other hand, when the melt
flow rate becomes too large, there are cases in which
the mechanical strength of the resin composition is
compromised, which is undesirable.
By blending in flame retardants in order to confer
non-flammability or self-extinguish-ability to the
compositions of this invention, flame-retarded
thermoplastic resin compositions can be obtained.
Halogenated organic compounds, mixtures of halogenated
organic compounds and antimony compounds, elementary
phosphorus, phosphorus compounds, compounds containing
phosphorus--nitrogen bonds, or mixtures of these can be
used as these flame retardants.
Those resin additives that are commonly employed,
in accordance with the use, in the polyphenylene oxide
resin compositions of the present invention, can be
suitably included. Examples that may be cited of these
include plasticizers, stabilizers, antioxidants,
pigments, dyes, drip retardants, treatment adjuvants,
inorganic mineral fillers, and fibrous, particulate,
flake-like or ground glass.
The resin compositions of this invention can
easily be prepared by a method that is itself known to
the art, such as a method involving the melting or
solution mixture of the thermoplastic resins. Suitable
examples that may be employed include methods whereby
these are fed to an extruder as pellets only, as
pellets and powders, or as powders only, and are
kneaded and extruded, methods whereby kneading and '
intimate mixture are carried out using a kneader or
rollers, and the blend is extruded in the form of a
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sheet, and methods whereby these are mixed as
solutions.
EXAMPLES
The present invention shall now be illustrated
more concretely by means~of examples.
The starting resins used in the application
examples and the comparative examples were as follows.
(1) Modified Polyphenylene Oxide Resin;
N50-4125 (manufactured by GE Plastics Japan)
(2) Ethylene-Carbon Monoxide-(Meth)acrylic Acid Ester
Copolymers;
(n-butyl acrylate was used as the(meth)acrylic
acid ester in each case)
(2-I) Ethylene-Carbon Monoxide-(Meth)acrylic Acid
Ester Copolymer I;
n-butyl acrylate content: 30 wt~
carbon monoxide content: 10 wt~
melt flow rate (190°C, 2160g): 25 g/10 minutes
(2-2) Ethylene-Carbon Monoxide-(Meth)acrylic Acid
Ester Copolymer 2;
n-butyl acrylate content: 30 wt~
carbon monoxide content: 13 wt~
melt flow rate (190°C, 2160g): 12 g/10 minutes
(3) Ethylene-Ethyl Acrylate Copolymer;
ethyl acrylate content: 25 wt~
melt flow rate (190°C, 2160g): 20 g/10 minutes
(Example 1-6)
The modified polyphenylene oxide resin and the
ethylene-carbon monoxide-n-butyl acrylate copolymer
were blended in the ratios shown in Table 1, and melt-
kneaded at 300°C using a twin-screw extruder having a
screw diameter of 30 mm (L/D = 25; with both screws
turning in the same direction).
The various physical properties were measured
using pellets of the compositions thus obtained, or
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test pieces fabricated by injection-molding these
compositions. The molding and measurement of the test
pieces for evaluating the physical properties were
carried~out under the conditions and method described
5 below:
(1) Molding of Test Pieces for Evaluating the Physical
Properties:
The composition pellets obtained by melt kneading
were injection-molded by means of an injection-molding
10 machine at a cylinder temperature of 290°C and a mold
temperature of 70-75°C, thereby fabricating test pieces
for measuring the heat distortion temperatures, Izod
impact strength and tensile strength.
(2) Heat Distortion Temperature:
Using injected-molded test pieces having a
thickness of 6.4 mm, measurement was carried out under
a load of 18.6 kg and in general accordance with JIS
K7207.
(3) Izod Impact Strength:
A v-notch was made in melt-molded test pieces
having a thickness of 3.2 mm, and the Izod impact
strength was measured in general accordance with ASTM
D256.
(4) Tensile Strength
Measurement was carried out in general accordance
with JIS K7113 on test pieces having the No. 1 test
piece shape indicated in JIS K7113 and a thickness of 3
mm.
(5) Melt Viscosity
This was measured by means of a capillograph made
by Toyo Seiki Seisakusho, using pellets of the
composition obtained by kneading in the extruder. (The
apparent melt viscosity at a measurement temperature of '
280°C and a shear rate of 1385 sec-1 was measured.)
(6) Layer-Like Peeling of the Molded Articles: '
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Square plates having a thickness of 2 mm were
obtained by injection molding, the square plate was
bent several times, and the peeling state in the bent
portion was observed. This was evaluated according to
the following criteria.'
O: no peeling
D: some peeling
X : severe peeling
(Comparative Example 1)
The physical properties were evaluated in the same
manner as in Application Examples 1-6 for modified
polyphenylene oxide resin by itself. The results are
given in Table 1.
(Comparative Examples 2-3)
Using an ethylene-ethyl acrylate copolymer in
place of the ethylene-carbon monoxide-n-butyl acrylate
copolymer in the present invention, this was blended
with a modified polyphenylene oxide resin in the mixing
ratios indicated in Table 1, melt-kneaded using an
extruder by the same method as in the application
examples, and the physical properties of the
compositions were measured. The results are presented
in Table 1.
30
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12
0
r1 l~ 1 I M W D M
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N '-1 N
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r- .f. ~t-> O ri
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r-Ir-iN N N N N cCS 'O ri r-I 'J I r-I
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As is apparent from Table 1, by means of the
present invention, the melt viscosity of a modified
polyphenylene oxide resin can be lowered without
lowering the heat distortion temperature of the same
resin, thereby enhancing the moldability, and also
giving a composition having an enhanced impact
resistance.
Moreover, as is also apparent from a comparison
with Comparative Examples 2-3, even though the
compositions of the present invention blend in a larger
amount of ethylene copolymer as a modifier than
compositions obtained by the formulation of ethylene-
unsaturated carboxylic acid ester copolymers, given
that a decreasing trend in the Izod impact strength is
not apparent, large amount of ethylene copolymer can be
formulated. This is also excellent with respect to the
peeling effect in the molded articles.
25
r
