U.S. patent application number 09/577773 was filed with the patent office on 2003-01-23 for molding material for oa machine parts with improved vibration damping properties.
Invention is credited to Kokubo, Akihiro, Kurasawa, Yoshihiro, Nishida, Koji.
Application Number | 20030018134 09/577773 |
Document ID | / |
Family ID | 27324586 |
Filed Date | 2003-01-23 |
United States Patent
Application |
20030018134 |
Kind Code |
A1 |
Kurasawa, Yoshihiro ; et
al. |
January 23, 2003 |
MOLDING MATERIAL FOR OA MACHINE PARTS WITH IMPROVED VIBRATION
DAMPING PROPERTIES
Abstract
The present invention relates to a molding material for OA
machine parts comprising a resin composition comprising: (1) 60 to
98 parts by weight of a polyphenylene ether-based resin comprising
10 to 100% by weight of a polyphenylene ether resin and 0 to 90% by
weight of a styrene-based resin, or a polycarbonate-based resin
comprising 50 to 100% by weight of a polycarbonate resin and 0 to
50% by weight of a styrene-based resin; (2) 2 to 40 parts by weight
of a thermoplastic elastomer which is a conjugated diene rubber
having not less than 50% by weight of 1,2-vinyl structure,
3,4-vinyl structure or mixture thereof, a styrene-conjugated diene
block copolymer having not less than 50% by weight of 1,2-vinyl
structure, 3,4-vinyl structure or mixture thereof, or a
hydrogenated product thereof; and (3) 1 to 50 parts by weight of a
flame retardant, the total amount of (1) polyphenylene ether-based
or polycarbonate-based resin and (2) thermoplastic elastomer being
100 parts by weight, said resin composition having bending modulus
of not less than 1500 MPa as measured at 23.degree. C. according to
ASTM D790, a damping ratio of not less than 1.0% at 23.degree. C.,
and a thermal deformation temperature of not less than 100.degree.
C. as measured according to ASTM D648 under 18.6 kg/cm.sup.2 load,
and the product of the bending modulus and the damping ratio being
not less than 10,000 MPa.multidot.%.
Inventors: |
Kurasawa, Yoshihiro;
(Hiratsuka-shi, JP) ; Kokubo, Akihiro;
(Hiratsuka-shi, JP) ; Nishida, Koji;
(Hiratsuka-shi, JP) |
Correspondence
Address: |
Dike Bronstein Roberts & Cushman LLP
EDWARDS & ANGELL
P.O. BOX 9169
Boston
MA
02209
US
|
Family ID: |
27324586 |
Appl. No.: |
09/577773 |
Filed: |
May 24, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09577773 |
May 24, 2000 |
|
|
|
09188622 |
Nov 9, 1998 |
|
|
|
Current U.S.
Class: |
525/132 |
Current CPC
Class: |
C08L 71/123 20130101;
C08L 69/00 20130101; C08L 71/123 20130101; C08L 25/00 20130101;
C08L 2666/02 20130101; C08L 2666/04 20130101; C08L 2666/24
20130101; C08L 53/00 20130101; C08L 69/00 20130101; C08L 71/123
20130101 |
Class at
Publication: |
525/132 |
International
Class: |
C08F 008/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 12, 1997 |
JP |
9-325153 |
Jun 25, 1998 |
JP |
10-178488 |
Claims
What is claimed is:
1. A molding material for OA machine parts comprising a resin
composition comprising: (1) 60 to 98 parts by weight of a
polyphenylene ether-based resin comprising 10 to 100% by weight of
a polyphenylene ether resin and 0 to 90% by weight of a
styrene-based resin, or a polycarbonate-based resin comprising 50
to 100% by weight of a polycarbonate resin and 0 to 50% by weight
of a styrene-based resin; (2) 2 to 40 parts by weight of a
thermoplastic elastomer which is a conjugated diene rubber having
not less than 50% by weight of 1,2-vinyl structure, 3,4-vinyl
structure or mixture thereof, a styrene-conjugated diene block
copolymer having not less than 50% by weight of 1,2-vinyl
structure, 3,4-vinyl structure or mixture thereof, or a
hydrogenated product thereof; and (3) 1 to 50 parts by weight of a
flame retardant, the total amount of (1) polyphenylene ether-based
or polycarbonate-based resin and (2) thermoplastic elastomer being
100 parts by weight, said resin composition having bending modulus
of not less than 1500 MPa as measured at 23.degree. C. according to
ASTM D790, a damping ratio of not less than 1.0% at 23.degree. C.,
and a thermal deformation temperature of not less than 100.degree.
C. as measured according to ASTM D648 under 18.6 kg/cm.sup.2 load,
and the product of the bending modulus and the damping ratio being
not less than 10,000 MPa.multidot.%.
2. The molding material according to claim 1, wherein the glass
transition temperature of the thermoplastic elastomer as measured
by DSC is -30 to 50.degree. C.
3. The molding material according to claim 1, wherein the resin
composition further contains an inorganic filler in an amount more
than 0% and not more than 60% by weight based on the weight of
molding material.
4. The molding material according to claim 3, wherein the inorganic
filler comprises a glass fiber in an amount of not less than 10% by
weight.
5. The molding material according to claim 1, wherein the amount of
(1) polyphenylene ether-based or polycarbonate-based resin is 72 to
97 parts by weight and the amount of (2) thermoplastic elastomer is
3 to 28 parts by weight.
6. The molding material according to claim 1, having a flammability
of V-0, V-1 or V-2 rank according to UL94 vertical combustion test
in which the specimen thickness is 1.6 mm.
7. The molding material according to claim 1, wherein the flame
retardant is a halogen-type flame retardant or phosphorus-type
flame retardant.
8. The molding material according to claim 7, wherein the
halogen-type flame retardant is a bromine-type flame retardant.
9. The molding material according to claim 7, wherein the
phosphorus-type flame retardant is a phosphate.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This is a continuation-in-part of application Ser. No.
09/188,622, filed Nov. 9, 1998.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a molding material for OA
machine parts with improved vibration-damping properties,
particularly it relates to such a molding material comprising a
polyphenylene ether-based or polycarbonate-based resin having high
mechanical strength, heat resistance and dimensional accuracy.
[0003] Since polyphenylene ether-based resins and
polycarbonate-based resins have many excellent properties such as
high mechanical strength, heat resistance, dimensional stability
and flame retardancy, they are popularly used as material of
various commercial products in many fields of industry, such as
typically electronic parts, electrical apparatus and automobile
parts.
[0004] Recently, most remarkably, these polyphenylene ether-based
and polycarbonate-based resins are used instead of the conventional
metals and thermosetting resins, as material of the business
machine parts, especially chassis parts of such office machines as
copiers and facsimiles, or the chassis parts or trays of the disc
drives such as CD-ROM drive, DVD, FDD, HDD, etc., used in personal
computers. This owes to the excellent properties such as high
mechanical strength, heat resistance, dimensional accuracy and
flame retardancy of the polyphenylene ether-based and
polycarbonate-based resins. In applications where high rigidity is
required, the reinforced polyphenylene ether or polycarbonate
resins containing inorganic fillers are used. Development of these
resin materials is also answering to the request for smaller size
and thickness of the products in recent years.
[0005] Lately, however, there has arisen the problem of vibration
incidental to the operational speed-up of the OA machines.
Vibrations generated at their source, such as motor in a device,
are transmitted to the resin-made parts, especially chassis parts,
to let them vibrate, which is liable to result in causing blurring
of the image or difficulty in reading data. For instance, the
increase of processing speed in the case of copying machines or the
increase of rotation speed in the case of disc drives such as
CD-ROM drive has boosted the generated frequency to a very high
level, such as 1,000 Hz in some cases, in contrast with the
frequency of up to about 200 Hz in the conventional devices.
[0006] Because of such elevation of the output frequency, it has
now become difficult to hold down vibrations of the chassis parts,
in which it has been possible to overcome by increasing thickness
or by proper designing of the rib structure in the conventional
products. In the resin material, efforts have been made to increase
rigidity by blending a greater amount of inorganic filler to raise
the resonance frequency, so that the resonance frequency may be
left out of the range of generated frequency. However, there is a
limitation due to excessive elevation of the generated frequency.
As another antivibration means from the resin material, it is
suggested to use a material which is capable of absorbing
vibrations. However, such vibration-absorbing materials are poor in
rigidity and heat resistance, and impracticable for the OA machine
parts.
[0007] Further, in a resin molding material for OA machine parts,
excellent flame-retardant property is required. Usually, the
flame-retardant property is evaluated by UL94 test. In a resin
molding material for OA machine parts, the flammability of V-0, V-1
or V-2 rank according to UL94 vertical combustion test is required.
However, it is difficult for a resin molding material for OA
machine parts to satisfy the excellent vibration damping properties
and excellent flame-retardant property, simultaneously.
[0008] Under these circumstances, there has been desired
development of a resin molding material having improved vibration
damping properties and flame-retardant property while maintaining
high mechanical strength and heat resistance required for the OA
machine parts.
[0009] As a result of the present inventors' earnest studies to
solve the above problem, it has been found that a molding material
comprising a polyphenylene ether-based or polycarbonate-based resin
composition having a specific modulus of elasticity and damping
ratio, is suited for the OA machine parts. The present invention
has been attained on the basis of the above finding.
SUMMARY OF THE INVENTION
[0010] An object of the present invention is to provide a molding
material for OA machine parts which has excellent vibration damping
properties and flame-retardant property, by .using a polyphenylene
ether-based or polycarbonate-based resin with high mechanical
strength, heat resistance and dimensional accuracy.
[0011] To attain the above aim, in an aspect of the present
invention, there is provided a molding material for OA machine
parts comprising a resin composition comprising:
[0012] (1) 60 to 98 parts by weight of a polyphenylene ether-based
resin comprising 10 to 100% by weight of a polyphenylene ether
resin and 0 to 90% by weight of a styrene-based resin, or a
polycarbonate-based resin comprising 50 to 100% by weight of a
polycarbonate resin and 0 to 50% by weight of a styrene-based
resin;
[0013] (2) 2 to 40 parts by weight of a thermoplastic elastomer
which is a conjugated diene rubber having not less than 50% by
weight of 1,2-vinyl structure, 3,4-vinyl structure or mixture
thereof, a styrene-conjugated diene block copolymer having not less
than 50% by weight of 1,2-vinyl structure, 3,4-vinyl structure or
mixture thereof, or a hydrogenated product thereof; and
[0014] (3) 1 to 50 parts by weight of a flame retardant,
[0015] the total amount of (1) polyphenylene ether-based or
polycarbonate-based resin and (2) thermoplastic elastomer being 100
parts by weight,
[0016] said resin composition having bending modulus of not less
than 1500 MPa as measured at 23.degree. C. according to ASTM D790,
a damping ratio of not less than 1.0% at 23.degree. C., and a
thermal deformation temperature of not less than 100.degree. C. as
measured according to ASTM D648 under 18.6 kg/cm.sup.2 load,
and
[0017] the product of the bending modulus and the damping ratio
being not less than 10,000 MPa.multidot.%.
BRIEF DESCRIPTION OF THE DRAWING
[0018] FIG. 1 is a schematic illustration of a damping ratio
measuring device.
DETAILED DESCRIPTION OF THE INVENTION
[0019] The term "OA machines" used in the present invention refers
to the business machines such as copiers, facsimiles, printers,
etc., as well as computer-related machines and devices, e.g. disc
drives such as CD-ROM drive, DVD, FDD, HDD or the like. The
"machine parts" refer to the structural parts of these machines and
devices, and a typical example thereof is chassis.
[0020] The "polyphenylene ether-based resins" usable in the present
invention may include polyphenylene ethers and mixtures of
polyphenylene ethers and styrene resins.
[0021] The "polyphenylene ethers" usable in the present invention
are the single polymers or copolymers having a structure
represented by the following formula: 1
[0022] wherein Q1s are each a halogen atom, a primary or secondary
alkyl group, an aryl group, an aminoalkyl group, a hydrocarbon oxy
group or a halohydrocarbon oxy group; Q2s are each a hydrogen atom,
a halogen atom, a primary or secondary alkyl group, an aryl group,
a haloalkyl group, a hydrocarbon oxy group or a halohydrocarbon oxy
group; and m is an integer not less than 10.
[0023] The preferred examples of the primary alkyl groups
represented by Q1 and Q2 are methyl, ethyl, n-propyl, n-butyl,
n-amyl, isoamyl, 2-methylbutyl, n-hexyl, 2,3-dimethylbutyl, and 2-,
3- or 4-methylpentyl or heptyl. The preferred examples of the
secondary alkyl groups represented by Q1 and Q2 are isopropyl,
sec-butyl and 1-ethylpropyl. In more preferable cases, Q1 is an
alkyl group or a phenyl group, especially an alkyl group having 1
to 4 carbon atoms, and Q2 is a hydrogen atom.
[0024] The polyphenylene ether single polymers used in the present
invention are preferably those comprising
2,6-dimethyl-1,4-phenylene ether units, and the copolymers are
preferably the random copolymers comprising a combination of the
said units and 2,3,6-trimethyl-1,4-phenyl- ene ether units. Many
preferred single polymers and random copolymers are described in
the patents and literature. The polyphenylene ethers having a
molecular structural portion which improves the polymer properties
such as molecular weight, melt viscosity and/or impact resistance,
are also preferred.
[0025] The polyphenylene ether used in the present invention is
preferably the one having an intrinsic viscosity of 0.2 to 0.8
dl/g, more preferably 0.2 to 0.7 dl/g, still more preferably 0.25
to 0.6 dl/g, as measured at 30.degree. C. in chloroform. When its
intrinsic viscosity is less than 0.2 dl/g, the produced composition
may be poor in impact resistance, and when the intrinsic viscosity
exceeds 0.8 dl/g, the composition may be unsatisfactory in
moldability.
[0026] The term "polycarbonate-based resins" used in the present
invention refers to the polycarbonate resins which may or may not
contain styrene resins. Examples of the polycarbonate resins usable
in the present invention may include aromatic polycarbonates,
aliphatic polycarbonates, and aliphatic-aromatic polycarbonates. Of
these resins, the aromatic polycarbonates comprising bisphenols,
such as 2,2-bis(4-oxyphenyl)alkane-- based,
bis(4-oxyphenyl)ether-based and bis(4-oxyphenyl)sulfone-, sulfide-
or sulfoxide-based resins are preferred. The polycarbonate resins
comprising halogen-substituted bisphenols may be used, if
necessary.
[0027] The polycarbonate used in the present invention is not
restricted in its molecular weight, but usually it has a molecular
weight of not less than 10,000, preferably 20,000 to 40,000.
[0028] The styrene-based resins usable in the present invention are
the copolymers comprising the aromatic vinyl compound repeating
units represented by the formula: 2
[0029] wherein R is hydrogen, an alkyl group having 1 to 4 carbon
atoms, or a halogen; Z is hydrogen, an alkyl group having 1 to 4
carbon atoms, a halogen or a vinyl group; and p is an integer of 1
to 5, and other copolymerizable monomers containing not less than
50% by weight of said repeating units.
[0030] Examples of such copolymers may include polystyrenes,
poly-.alpha.-methylstyrene, rubber-reinforced polystyrenes,
styrene-acrylonitrile copolymer,
styrene-acrylonitrile-(-alkylstyrene copolymer,
acrylonitrile-butadiene-styrene copolymer,
acrylonitrile-butadiene-(-methylstyrene copolymer, styrene-maleic
anhydride copolymer, and styrene-maleimide copolymer.
[0031] Rubber-reinforced polystyrenes can be formed by using as
rubber reinforcement diene rubber, isoprene rubber,
styrene-butadiene rubber, styrene-isoprene rubber, acrylic rubber,
ethylene-propylene rubber, ethylene-octene rubber, EPDM rubber or
the like.
[0032] Of these copolymers, polystyrenes, rubber-modified
polystyrenes, acrylonitrile-styrene copolymer,
acrylonitrile-butadiene-styrene copolymer and mixtures thereof are
especially preferred.
[0033] The amount of a styrene-based resin contained in a
polyphenylene ether-based resin is preferably 0 to 90% by weight,
more preferably 1 to 70% by weight, still more preferably 2 to 50%
by weight based on the sum of polyphenylene ether and styrene-based
resin. When the content exceeds 90% by weight, the produced
composition may be low in heat resistance.
[0034] In the case of the polycarbonate-based resins, the
styrene-based resin content is preferably 0 to 50% by weight, more
preferably 1 to 45% by weight, even more preferably 5 to 40% by
weight based on the sum of polycarbonate resin and styrene-based
resin. When the content exceeds 50% by weight, the produced
composition may be low in heat resistance.
[0035] It is also preferable to contain an inorganic filler in the
resin composition of the present invention. Any type of inorganic
filler generally used in the thermoplastic resins can be used in
the present invention. Examples of the inorganic fillers usable in
the present invention may include fibrous fillers such as glass
fiber, carbon fiber and metal fiber, whiskers such as potassium
titanate whisker, magnesium sulfate whisker, aluminum borate
whisker, calcium carbonate whisker, silicon carbide whisker, zinc
oxide whisker and wollastrite, plate-like fillers such as mica,
talc and glass flakes, and granular fillers such as calcium
carbonate, clay, kaolin, barium sulfate, silica, alumina, magnesium
oxide, magnesium sulfate, metallic powder, glass beads and glass
powder. These fillers may be used either singly or as a mixture of
two or more of them according to the purpose of use of the produced
molding material. Also, these fillers may be surface treated with
various types of coupling agent to improve their adhesiveness to
the resin.
[0036] The content of the inorganic filler in the composition is
usually 0 to 60% by weight, preferably 5 to 55% by weight, more
preferably 10 to 50% by weight based on the weight of molding
material. In case where applications require a high modulus of
elasticity, a too small filler content may be not preferred. When
the filler content exceeds 60 parts by weight, the obtained
composition may be deteriorated affected in impact strength,
resulting in poor moldability of the composition.
[0037] It is preferred that the filler comprises not less than 10%
by weight, preferably not less than 20% by weight of glass fiber.
In case where the resin composition contains glass fiber in the
above-mentioned amount, the molding product comprising the resin
composition has higher impact strength and higher rigidity in
comparison with the case of a resin composition containing only
mica as the inorganic filler.
[0038] In the present invention, a thermoplastic elastomer is added
for the purpose of improving vibration damping properties of the
molding material. The thermoplastic elastomers usable for the said
purpose in the present invention may include conjugated diene
rubbers such as butadiene rubber and isoprene rubber,
styrene-conjugated diene block copolymers and their hydrogenation
products, ethylene-.alpha.-olefin copolymer rubber, nylon
elastomers, polyester elastomers, urethane elastomers, silicon
elastomers, fluorine elastomers, and core-shell type elastomers. Of
these elastomers, conjugated diene rubbers, styrene-conjugated
diene block copolymers and their hydrogenation products are
preferred, and those of the conjugated diene rubbers containing not
less than 50% by weight of the structural units having a 1,2-vinyl
and/or 3,4-vinyl structure, those of the styrene-conjugated diene
block copolymers containing not less than 50% by weight of the
structural units having a 1,2-vinyl and/or 3,4-vinyl structure, and
their hydrogenation products are especially preferred. It is
preferable to introduce into these elastomers a functional group
having affinity for or reactivity with polyphenylene ether-based or
polycarbonate-based resins for the purpose of improving affinity of
the composition for such resins. The elastomers used in the present
invention preferably have a DSC-determined glass transition
temperature between -30 and 50.degree. C., more preferably between
-20 and 30.degree. C.
[0039] The amount of the thermoplastic elastomer blended is 2 to 40
parts by weight, preferably 3 to 28 parts by weight, more
preferably 5 to 25 parts by weight based on 100 parts by weight of
the resin components of the composition. On the other hand, the
amount of polyphenylene ether-based or polycarbonate-based resin is
60 to 98 parts by weight, preferably 72 to 97 parts by weight, more
preferably 75 to 95 parts by weight based on 100 parts by weight of
the resin components of the composition. The total amount of
polyphenylene ether-based or polycarbonate-based resin and
thermoplastic elastomer is 100 parts by weight. If the amount of
the thermoplastic elastomer is less than 2 parts by weight, the
improvement of vibration damping properties may not be obtained,
while if its amount exceeds 40 parts by weight, the modulus of
elasticity of the composition may lower excessively.
[0040] As other components of the composition of the present
invention, it is possible to add the materials commonly used for
the thermoplastic resin preparations, such as antioxidant,
weathering resistance improver, nucleating agent, impact resistance
improver, plasticizer, fluidity improver, etc. Known types of
colorants and their dispersants can also be used for enhancing
practicality of the composition.
[0041] It is further possible to add other types of thermoplastic
resins such as polyolefins, polyamides, polyesters, polyarylene
sulfide, etc., within limits not prejudicial to the intended effect
of the present invention. The amount of these resins added, but it
is preferable that the amount of the other thermoplastic resins is
0 to 30 parts by weight based on the total amount (100 parts by
weight) of the polyphenylene ether-based or polycarbonate-based
resin and the thermoplastic elastomer.
[0042] The resin composition according to the present invention
essentially contains a flame retardant. As the flame retardant,
various known types of flame retardant can be used in the present
invention and there are exemplified halogen-type flame retardants
such as bromine-type flame retardants, chlorine-type flame
retardants and fluorine-type flame retardants, antimony-type flame
retardants, phosphorus-type flame retardants and nitrogen-type
flame retardants. Of these, halogen-type flame retardants and
phosphorus-type flame retardants are preferably used.
[0043] As the halogen-type flame retardant, bromine-type flame
retardant is preferred, especially, the bromine-type flame
retardant comprising a bromine substituted-aromatic compound is
preferred in view of heat resistance. As the bromine
substituted-aromatic compound, there are exemplified brominated
bisphenol "A", epoxy resins made from brominated bisphenol "A"s as
the starting material, polycarbonates resins made from brominated
bisphenol A as the starting material, brominated polystyrenes and
brominated polyphenylene ether.
[0044] The amount of the halogen-type flame retardant in the resin
composition is 1 to 50 parts by weight, preferably 1 to 30 parts by
weight, more preferably 1 to 20 parts by weight based on the total
amount (100 parts by weight) of the polyphenylene ether-based or
polycarbonate-based resin and the thermoplastic elastomer. When the
amount of the halogen-type flame retardant is less than 1 part by
weight, the flame retardancy may not be sufficient. When the amount
of the halogen-type flame retardant is more than 50 parts by
weight, the residence heat stability in the molding process may be
deteriorated. It is preferable that the halogen-type flame
retardant is used in combination of antimony compounds such as
antimony trioxide, antimony tetraoxide and sodium antimonate, as
the flame-retardant assistant. The amount of the flame-retardant
assistant used is usually 1/2 to 1/10 amount of the weight of the
halogen-type flame retardant.
[0045] As the phosphorus-type flame retardant, phosphates and red
phosphorus are preferred. Of these, phosphates, especially aromatic
phosphates are preferred. As the aromatic phosphates, there are
exemplified mono-phosphates such as triphenyl phosphate, tricrezyl
phosphate and trixylyl phosphate, and condensed type aromatic
phosphates having a residue of aromatic dialcohol such as bisphenol
A, resorcinol, hydroquinone and biphenol. The condensed type
aromatic phosphates are easily available as the commercial products
such as CR733S and CR741 (produced by Daihachi Chemical Co., Ltd.),
and FP500 (Asahi Denka Kogyo KK).
[0046] The amount of the phosphateas the flame retardant in the
resin composition is 1 to 50 parts by weight, preferably 3 to 40
parts by weight, more preferably 5 to 30 parts by weight based on
the total amount (100 parts by weight) of the polyphenylene
ether-based or polycarbonate-based resin and the thermoplastic
elastomer. When the amount of the phosphate is less than 1 part by
weight, the flame retardancy may not be sufficient. When the amount
of the phosphate is more than 50 parts by weight, the residence
heat stability in the molding process may be deteriorated.
[0047] In the resin composition according to the present invention,
it is preferred that an anti-drip agent is used in combination of
the flame-retardant. As the anti-drip agent, fluorine compounds
such as polytetrafluoroethylene are preferred. The amount of the
fluorine compounds as the anti-drip agent is usually 0.01 to 2
parts by weight, preferably 0.05 to 1.5 parts by weight, especially
preferably 0.1 to 1 part by weight based on the total amount (100
parts by weight) of the polyphenylene ether-based or
polycarbonate-based resin and the thermoplastic elastomer.
[0048] In the present invention, the molding material comprising
the resin composition has a flammability (flame-retardant property)
of usually V-0, V-1 or V-2 rank, preferably V-0 or V-1 rank,
especially preferably V-0 rank according to UL94 vertical
combustion test in which the specimen thickness is 1.6 mm. This
flammability rank (V-0, V-1 or V-2) is required in a molding
material for OA machine parts.
[0049] It is essential for the molding material for OA machine
parts with excellent vibration damping properties according to the
present invention that the properties of their thermoplastic resin
composition satisfy the following requirements.
[0050] (1) The bending modulus measured at 23.degree. C. according
to ASTM D790 is not less than 1,500 MPa, preferably not less than
2,000 MPa, more preferably not less than 2,800 MPa. If the bending
modulus is less than 1,500 MPa, the composition may lack rigidity
and be not preferred for OA machines parts.
[0051] (2) The damping ratio at 23.degree. C. is not less than
1.0%, preferably not less than 1.5%. When the damping ratio is less
than 1.0%, the composition may lack preferred vibration damping
performance. The damping ratio shown here is the one at a primary
natural frequency, which can be determined by giving vibrations,
with an impulse hammer, to a test piece to which an acceleration
pickup sensor is attached, and making calculations from the signals
from the pick up sensor and the force sensor attached to the
impulse hammer (see FIG. 1).
[0052] (3) The thermal deformation temperature as measured
according to ASTM D648 under 18.6 kg/cm.sup.2 is not less than
100.degree. C., preferably not less than 110.degree. C. When the
thermal deformation temperature is less than 100.degree. C., the
composition may be subject to deformation by the heat in use and,
therefore, not preferable for OA machine parts.
[0053] (4) The product of bending modulus and damping ratio is not
less than 10,000 MPa, preferably not less than 11,000 MPa, more
preferably not less than 12,000 MPa. Bending modulus and damping
ratio are in a conflicting relation to each other, and when their
product is less than 10,000 MPa, they are poorly balanced and
preferred for OA machine parts.
[0054] Methods for production and molding of the composition are
explained below.
[0055] Various methods are available for obtaining the
thermoplastic resin composition of the present invention. In one
method, for instance, the above-mentioned components are mixed and
kneeded by various types of mixer such as single- or multi-screw
mixer, Banbury mixer, roll mixer, Brabender Plastogram or the like,
and then cooled and solidified. In another method (dissolution
mixing method), the said components are added to a preferable
solvent, for example, a hydrocarbon such as hexane, heptane,
benzene, toluene and xylene or a derivative thereof, and the
dissolved components or the dissolved and undissolved components
are mixed in a suspended state. The former (mixing and kneeding)
method is preferred from the viewpoint of industrial cost.
[0056] The molding method for the molding material for OA machine
parts with excellent vibration damping properties according to the
present invention is not specified, but it is possible to apply the
methods generally used for molding of thermoplastic resin
compositions, such as injection molding, hollow molding, extrusion
molding, sheet molding, heat forming, rotational molding and
laminate molding.
[0057] As is apparent from the foregoing embodiments, the molded
products according to the present invention have improved vibration
damping properties and flame-retardant property in addition to high
mechanical strength, heat resistance and dimensional accuracy, and
are preferred for application to OA machine parts for which the
requirement for vibration damping properties is expected to become
stronger in the future.
EXAMPLES
[0058] The present invention is further illustrated by showing the
examples thereof, but the invention is not limited to these
examples.
[0059] The following materials were used as components of the
composition.
[0060] 1. Polyphenylene ether (PPE):
poly(2,6-dimethyl-1,4-phenylene ether) (intrinsic viscosity
measured in chloroform at 30.degree. C. 0.40 dl/g, produced by
Mitsubishi Gas Chemical Co., Ltd.)
[0061] 2. Polycarbonate resin (PC): bisphenol A-polycarbonate
(trade name: IUPIRON S3000, viscosity-average molecular
weight=21,000, produced by Mitsubishi Engineering-Plastics
Corporation)
[0062] 3. Xylon 500H: modified PPE resin based on
poly(2,6-dimethyl-1,4-ph- enylene)ether (density=1.06)
[0063] 4. Styrene-based resins
[0064] PS-1: polystyrene (trade name: DIAREX HF77, produced by
Mitsubishi Chemical Corporation)
[0065] PS-2: rubber-reinforced polystyrene (trade name: DIAREX HT
478, produced by Mitsubishi Chemical Corporation)
[0066] ABS: acrylonitrile-butadiene-styrene copolymer (trade name:
SANTAC UT60B, produced by Mitsui Chemical Co., Ltd.)
[0067] 5. Thermoplastic elastomers
[0068] HYBRAR: styrene-isoprene block copolymer (trade name: HYBRAR
VS-1, produced by Kuraray Co., Ltd.; proportion of the structural
units having a 1,2-vinyl and/or 3,4-vinyl structure =70 wt %; glass
transition point=8.degree. C.)
[0069] KRATON: hydrogenated styrene-butadiene-styrene block
copolymer (trade name: KRATON G1651, produced by Shell Chemical
Co.; proportion of the structural units having a 1,2-vinyl and/or
3,4-vinyl structure 0 wt %; glass transition point=-60.degree.
C.)
[0070] 6. Flame-retardant
[0071] TPP: triphenyl phosphate
[0072] Br-PC: tetrabromobisphenol A-polycarbonate oligomer (trade
name: IUPIRON FR53, produced by Mitsubishi Engineering-Plastics
Corporation)
[0073] PTFE: polytetrafluoroethylene (trade name: POLYFLON F201,
produced by Daikin Industries Co., Ltd.)
[0074] 7. Inorganic fillers
[0075] Glass fiber: E-glass fiber having an average diameter of 10
.mu.m and a length of 3 mm
[0076] Glass flakes: trade name: REFG-101, produced by Nippon Sheet
Glass Co., Ltd.
[0077] Mica: average particle size=50 .mu.m
[0078] The properties of the products were evaluated by the
following methods.
[0079] (1) Izod Impact Test
[0080] A notched izod impact test was carried out according to ASTM
D256.
[0081] In the present invention, the izod impact is preferably not
less than 30 J/m.
[0082] (2) Bending Modulus
[0083] A three-point bending test was conducted according to the
bending test method of ASTM D790.
[0084] In the present invention, the bending modulus is preferably
not less than 1500 MPa.
[0085] (3) Thermal Deformation Temperature
[0086] A deformation-under-load test was carried out under the
condition of 18.6 kg/cm.sup.2 according to ASTM D648.
[0087] In the present invention, the thermal deformation
temperature is preferably not less than 80.degree. C.
[0088] (4) Damping Ratio
[0089] An ASTM test piece (1/2".times.1/4") made under the
above-described conditions was fixed by a bias as shown in FIG. 1,
and an acceleration pickup sensor was attached to an end of the
test piece. Then the test piece was hit by an impulse hammer
(GK3100 mfd. by Ono Sokuki KK) to let it vibrate, and the signals
form the pickup and the force sensor attached to the impulse hammer
were input to an FFT analyzer (CF-350Z mfd. by Ono Sokuki KK) to
determine the transfer function G(t) of the material.
G(t)=X(t)/F(t)
[0090] X(t): output signal
[0091] F(t): input signal
[0092] The damping ratio at the primary natural frequency was
calculated from the determined transfer function G(t) according to
the half-value width method.
[0093] In the present invention, the damping ratio is preferably
not less than 1.0%.
[0094] (5) Dimensional Accuracy
[0095] Using an in-line injection molder (clamping force: 100 T), a
100 mm.times.100 mm.times.2 mm thick flat plate was made by
injection molding with a film gate, and the clearance was measured
on a platen to determine warpage. Cylinder and mold temperatures
were as follows.
[0096] Cylinder temperature:
[0097] 280.degree. C.: in Examples 1-5 and Comparative Examples
1-4, 7 and 9-10
[0098] 220.degree. C.: in Comparative Examples 5-6 and 15
[0099] 300.degree. C.: in Reference Examples 1-2, Example 6 and
Comparative Examples 11-13
[0100] 270.degree. C.: in Reference Example 3, Example 7 and
Comparative Example 14
[0101] 260.degree. C.: in Comparative Example 8 and 16
[0102] Mold temperature:
[0103] 60.degree. C.: in Examples 1-5 and Comparative Examples 1-4,
7 and 9-10
[0104] 40.degree. C.: in Comparative Examples 5-6 and 15
[0105] 80.degree. C.: in Examples 6-7, Comparative Examples 8,
11-14 and 16, and Reference Examples 1-3
[0106] In the present invention, the warpage is preferably not more
than 3.0 mm.
[0107] (6) MFR
[0108] Measured under the conditions of 280.degree. C. and 5 kg
according to ASTM D1238.
[0109] In the present invention, the MFR is preferably 0.5 to 100
g/10 min.
[0110] (7) Flammability (Flame-Retardant Property):
[0111] According to the method prescribed in UL94 vertical
combustion test, a test specimen having a thickness of 1.6 mm. In
the present invention, flammability is preferably V-0, V-1 or V-2,
more preferably V-0 or V-1, especially preferably V-0.
Examples 1-5 and Comparative Examples 1-7 and 9-10
[0112] The materials shown in Table 1 were blended in the ratios
also shown in Table 1 using a twin-screw extruder(mfd. by Japan
Steel Works, Ltd.) at a cylinder temperature of 210.degree. C. and
a screw speed of 250 rpm to obtain the resin compositions. These
resin compositions were injection molded to make the test pieces
using an in-line injection molding machine (clamping force: 50 T)
under the conditions of cylinder temperature of 280.degree. C. and
mold temperature of 60.degree. C., and the test pieces were
evaluated by the methods explained above. The results are shown in
Table 1.
[0113] In Comparative Examples 5 and 6, the injection molding
machine was operated at a cylinder temperature of 220.degree. C.
and a mold temperature of 40.degree. C.
Comparative Example 8
[0114] A 30% glass fiber-reinforced PBT (NOVADUR 5010GN1-30,
produced by Mitsubishi Engineering-Plastics Corporation) was
injection molded to make a test piece using an in-line injection
molding machine (clamping force: 50 T) under the condition of
cylinder temperature of 255.degree. C. and mold temperature of
80.degree. C., and the test piece was evaluated by the
above-described methods. The results are shown in Table 1.
1 TABLE 1 Example Example Example Example 1 2 3 4 Composition PPE
(parts by weight) 60 55 75 75 PS-1 (parts by weight) 20 25 5 5
Thermoplastic elastomer HYBRAR (parts by 20 20 20 20 weight) KRATON
(parts by -- -- -- -- weight) TPP (parts by weight) 12 12 17 17
Inorganic filler Glass fiber (wt %) -- -- 30 25 Mica (wt %) -- 15
-- 15 Properties Izod impact strength 100 45 105 95 (J/m) Bending
modulus (MPa) 2300 3100 7200 9000 Thermal deformation 105 105 130
130 temperature (.degree. C.) Damping ratio 5.1 4.0 2.3 1.9 Bending
modulus .times. 11730 12400 16560 17100 damping ratio (MPa) MFR
(g/10 min) 14 12 5 4 Warpage (mm) 0.5 0.5 2.0 1.5 Flammability V-1
V-1 V-0 V-0 Comp Comp. Comp. Example Example Example Example 5 1 2
3 Composition PPE (parts by weight) 90 60 40 75 PS-1 (parts by
weight) -- 40 -- 25 Thermoplastic elastomer HYBRAR (parts by 10 --
60 -- weight) KRATON (parts by -- -- -- -- weight) TPP (parts by
weight) 20 12 12 17 Inorganic filler Glass fiber (wt %) 20 -- -- 30
Mica (wt %) 15 -- -- -- Properties Izod impact strength 100 15 200
80 (J/m) Bending modulus (MPa) 8300 3000 700 7800 Thermal
deformation 125 102 80 115 temperature (.degree. C.) Damping ratio
1.6 2.1 10.2 0.8 Bending modulus .times. 13280 6300 7140 6240
damping ratio (MPa) MFR (g/10 min) 1 20 9 7 Warpage (mm) 0.4 0.5
1.5 2.0 Flammability V-0 V-1 V-1 V-0 Comp. Comp Comp. Comp. Example
Example Example Example 4 5 6 7 Composition PPE (parts by weight)
60 20 -- 75 PS-1 (parts by weight) 20 60 80 5 Thermoplastic
elastomer HYBRAR (parts by 20 20 20 -- weight) KRATON (parts by --
-- -- 20 weight) TPP (parts by weight) -- 12 -- 17 Inorganic filler
Glass fiber (wt %) 20 -- -- 25 Mica (wt %) 15 -- -- 15 Properties
Izod impact strength 100 70 20 115 (J/m) Bending modulus (MPa) 2200
2400 2200 8700 Thermal deformation 140 55 60 128 temperature
(.degree. C.) Damping ratio 5.0 4.7 4.9 0.7 Bending modulus .times.
11000 11280 10780 6090 damping ratio (MPa) MFR (g/10 min) 3 45 80 5
Warpage (mm) 0.5 0.6 1.5 1.6 Flammability no good no good no good
V-0 Comp. Comp. Comp. Example Example Example 8 9 10 Composition
PPE (parts by weight) -- -- -- PS-1 (parts by weight) -- -- --
Xylon 500 H (parts by -- 70 70 weight) Thermoplastic elastomer
HYBRAR (parts by -- 30 30 weight) KRATON (parts by -- -- -- weight)
TPP (parts by weight) -- -- -- Inorganic filler Glass fiber (wt %)
-- -- -- Mica (wt %) -- -- 38 Properties Izod impact strength 95
300 40 (J/m) Bending modulus (MPa) 8500 1300 6000 Thermal
deformation 205 90 95 temperature (.degree. C.) Damping ratio 0.6
6.0 2.0 Bending modulus .times. 5100 7800 12000 damping ratio (MPa)
MFR (g/10 min) 80 20 10 Warpage (mm) 5.5 2.5 1.3 Flammability V-0
no good no good
Reference Examples 1-2, Example 6 and Comparative Examples
11-13
[0115] The materials shown in Table 2 were melt mixed in the ratios
also shown in the table using a twin-screw extruder (mfd. by Japan
Steel Works, Ltd.) at a cylinder temperature of 280.degree. C. and
a screw speed of 250 rpm to obtain the resin compositions. These
resin compositions were injection molded to make the test pieces
using an in-line injection molding machine (clamping force: 50 T)
under the conditions of cylinder temperature of 300.degree. C. and
mold temperature of 80.degree. C., and the test pieces were
evaluated in the manner described above. The results are shown in
Table 2.
Reference Example 3, Example 7 and Comparative Example 14
[0116] The materials shown in Table 2 were melt mixed by a
twin-screw extruder (mfd. by Japan Steel Works, Ltd.) at a cylinder
temperature of 250.degree. C. and a screw speed of 250 rpm to
obtain the resin compositions. These resin compositions were
injection molded to make the test pieces using an in-line injection
molding machine (clamping force: 50 T) at a cylinder temperature of
270.degree. C. and a mold temperature of 80.degree. C., and the
test pieces were evaluated in the manner described above. The
results are shown in Table 2.
Comparative Example 15
[0117] The materials were melt mixed in the ratios shown in Table 2
using a twin-screw extruder (mfd. by Japan Steel Works, Ltd.) at a
cylinder temperature of 250.degree. C. and a screw speed of 250 rpm
to obtain a resin composition. This resin composition was injected
molded to make a test piece using an in-line injection molding
machine (clamping force: 50 T) under the conditions of cylinder
temperature of 220.degree. C. and mold temperature of 40.degree.
C., and the test piece was evaluated in the manner described above.
The results are shown in Table 2.
Comparative Example 16
[0118] A 30% glass fiber-reinforced PBT (trade name: NOVADUR
5010GN-1-30, produced by Mitsubishi Engineering-Plastics
Corporation) was injection molded to make a test piece using an
in-line injection molding machine (clamping force: 50 T) under the
conditions of cylinder temperature of 255.degree. C. and mold
temperature of 80.degree. C., and the test piece was evaluated in
the manner described above. The results are shown in Table 2.
2TABLE 2 Ref. Ref. Ref. Example Example Example Example 1 2 6 3
Composition PC (parts by weight) 80 80 80 63 Styrene resin PS
(parts by weight) -- -- -- -- ABS (parts by weight) -- -- -- 27
Thermoplastic elastomer HYBRAR (parts by 20 20 20 10 weight) KRATON
(parts by -- -- -- -- weight) Flame retardant Br-PC (parts by -- --
10 -- weight) PTFE (parts by weight) -- -- 0.3 -- Inorganic filler
Glass fiber (wt %) -- 30 10 30 Glass flakes (wt %) -- -- 20 --
Properties Izod impact strength 600 96 52 82 (J/m) Bending modulus
(MPa) 1950 6200 5400 6800 Thermal deformation 132 144 140 128
temperature (.degree. C.) Damping ratio 5.3 2.2 2.3 1.5 Bending
modulus .times. 10335 13640 12420 10200 damping ratio (MPa) Warpage
(mm) 0.4 1.8 0.4 2.0 Flammability no good no good V-0 no good Comp.
Comp. Comp. Example Example Example Example 7 11 12 13 Composition
PC (parts by weight) 63 100 40 80 Styrene resin PS (parts by
weight) 27 -- -- -- ABS (parts by weight) -- -- -- -- Thermoplastic
elastomer HYBRAR (parts by 10 -- 60 -- weight) KRATON (parts by --
-- -- 20 weight) Flame retardant Br-PC (parts by 15 -- -- --
weight) PTFE (parts by weight) 0.3 -- -- -- Inorganic filler Glass
fiber (wt %) 30 -- -- 30 Glass flakes (wt %) -- -- -- -- Properties
Izod impact strength 76 780 700 94 (J/m) Bending modulus (MPa) 6700
2300 700 6100 Thermal deformation 124 138 80 140 temperature
(.degree. C.) Damping ratio 1.6 2.1 10.4 0.7 Bending modulus
.times. 10720 4830 7280 4270 damping ratio (MPa) Warpage (mm) 2.1
0.4 1.5 1.9 Flammability V-0 no good no good no good Comp. Comp.
Comp. Example Example Example 14 15 16 Composition PC (parts by
weight) 70 -- (PBT) Styrene resin PS (parts by weight) -- 80 -- ABS
(parts by weight) 30 -- -- Thermoplastic elastomer HYBRAR (parts by
-- 20 -- weight) KRATON (parts by -- -- -- weight) Flame retardant
Br-PC (parts by -- -- -- weight) PTFE (parts by weight) -- -- --
Inorganic filler Glass fiber (wt %) 30 -- 30 Glass flakes (wt %) --
-- -- Properties Izod impact strength 96 20 95 (J/m) Bending
modulus (MPa) 7400 2200 8500 Thermal deformation 131 60 205
temperature (.degree. C.) Damping ratio 0.7 4.9 0.6 Bending modulus
.times. 5180 10780 5100 damping ratio (MPa) Warpage (mm) 2.2 1.5
5.5 Flammability no good no good V-0
* * * * *