U.S. patent application number 11/547191 was filed with the patent office on 2008-10-09 for thermoplastic resin composition and resin molding.
Invention is credited to Norifumi Sumimoto.
Application Number | 20080248227 11/547191 |
Document ID | / |
Family ID | 35125034 |
Filed Date | 2008-10-09 |
United States Patent
Application |
20080248227 |
Kind Code |
A1 |
Sumimoto; Norifumi |
October 9, 2008 |
Thermoplastic Resin Composition and Resin Molding
Abstract
The present invention provides a thermoplastic resin composition
producing an extremely small amount of outgas and providing a
molded article having excellent antistaticity. The present
thermoplastic resin composition comprises a thermoplastic resin and
is characterized in that the amount of outgas is 1500 .mu.g/g or
less. The composition may comprise a surface resistivity reducing
substance in an amount of 0.1 to 70 parts by mass relative to 100
parts by mass of the thermoplastic resin. The present invention is
suitable to a composition comprising a styrenic resin as the
thermoplastic resin. The surface resistivity reducing substrate is
preferably a polyamide elastomer comprising a hard segment formed
of polyamide 12 and a soft segment formed of poly(alkylene
oxide)glycol. The polyamide elastomer preferably has a refractive
index of 1.5 to 1.53, a melting point of 130 to 160.degree. C., a
solution viscosity of 1.35 to 1.70 and a surface resistivity of
1.times.10.sup.8 to 1.times.10.sup.11.OMEGA..
Inventors: |
Sumimoto; Norifumi; (Tokyo,
JP) |
Correspondence
Address: |
FITCH, EVEN, TABIN & FLANNERY
P. O. BOX 18415
WASHINGTON
DC
20036
US
|
Family ID: |
35125034 |
Appl. No.: |
11/547191 |
Filed: |
March 25, 2005 |
PCT Filed: |
March 25, 2005 |
PCT NO: |
PCT/JP05/05515 |
371 Date: |
September 29, 2006 |
Current U.S.
Class: |
428/35.7 ;
525/187; 525/408 |
Current CPC
Class: |
C08F 255/04 20130101;
C08L 25/12 20130101; C08F 220/14 20130101; C08F 279/02 20130101;
Y10T 428/13 20150115; C08L 25/14 20130101; C08F 279/02 20130101;
C08L 77/02 20130101; C08G 69/40 20130101; C08F 212/08 20130101;
C08L 25/12 20130101; C08L 77/06 20130101; C08L 2666/02 20130101;
C08L 2666/24 20130101; C08F 212/10 20130101; C08L 2666/02 20130101;
C08L 2666/02 20130101; C08L 2666/02 20130101; C08F 212/10 20130101;
C08L 51/06 20130101; C08F 255/04 20130101; C08L 2666/02 20130101;
C08F 212/10 20130101; C08L 77/02 20130101; C08F 279/04 20130101;
C08L 55/02 20130101; C08L 51/04 20130101; C08L 55/02 20130101; C08L
25/12 20130101; C08L 51/06 20130101; Y10T 428/1352 20150115; B65D
25/107 20130101; C08F 220/281 20200201; C08F 220/44 20130101; C08L
51/04 20130101 |
Class at
Publication: |
428/35.7 ;
525/187; 525/408 |
International
Class: |
B32B 1/02 20060101
B32B001/02; C08L 71/02 20060101 C08L071/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2004 |
JP |
2004-106612 |
Jul 13, 2004 |
JP |
2004-206385 |
Claims
1. A thermoplastic resin composition comprising a thermoplastic
resin (A), which has outgas in an amount of 1500 .mu.g/g or
less.
2. The thermoplastic resin composition according to claim 1,
further comprising a surface resistivity reducing substance (B) in
an amount of 0.1 to 70 parts by mass relative to 100 parts by mass
of the thermoplastic resin (A).
3. The thermoplastic resin composition according to claim 1, in
which the thermoplastic resin (A) comprises a styrenic resin.
4. The thermoplastic resin composition according to claim 1, in
which the surface resistivity reducing substrate (B) is a polyamide
elastomer which comprises a hard segment comprising polyamide 12
and a soft segment comprising poly(alkylene oxide)glycol.
5. The thermoplastic resin composition according to claim 4, in
which the polyamide elastomer has a refractive index of 1.5 to
1.53, a melting point of 130 to 160.degree. C., a solution
viscosity of 1.35 to 1.7 and a surface resistivity of
1>10.sup.8to 1.times.10.sup.11.OMEGA..
6. An antistatic agent comprising a polyamide elastomer which
comprises a hard segment comprising polyamide 12 and a soft segment
comprising poly(alkylene oxide)glycol, in which the polyamide
elastomer has a refractive index of 1.5 to 1.53, a melting point of
130 to 160.degree. C., a solution viscosity of 1.35 to 1.7 and a
surface resistivity of 1.times.10.sup.8 to
1.times.10.sup.11.OMEGA..
7. A resinous molded article formed of the thermoplastic resin
composition according to claim 1, in which the resinous molded
article has a surface resistivity value of 1.times.10.sup.11.OMEGA.
or less.
8. The resinous molded article according to claim 7, which has a
taber abrasion index of less than 30.
9. The resinous molded article according to claim 7, which is a
container used for receiving at least one selected from the group
consisting of a semiconductor related component, a semiconductor
related device, a liquid crystal related component and a liquid
crystal related device.
10. The thermoplastic resin composition according to claim 2, in
which the thermoplastic resin (A) comprises a styrenic resin.
11. The resinous molded article according to claim 8, which is a
container used for receiving at least one selected from the group
consisting of a semiconductor related component, a semiconductor
related device, a liquid crystal related component and a liquid
crystal related device.
Description
TECHNICAL FIELD
[0001] The present invention relates to a thermoplastic resin
composition which generates an extremely small amount of outgas and
provides molded articles excellent in antistaticity, abrasion
resistance, impact resistance and transparency, and also relates to
a molded article made of the thermoplastic resin composition. More
particularly, the present invention relates to a thermoplastic
resin composition which is highly purified more than ever by
removing impurities such as monomers used in resin production and,
as a result, reduced in outgas generation, and also relates to a
molded article thereof. Most particularly, the present invention
relates to a thermoplastic resin composition which is blended with
a specific substance for reducing a surface resistivity and is thus
extremely reduced in outgas generation, and also relates to a
molded article thereof.
BACKGROUND ART
[0002] Recently, with progress of the chemical industry, industrial
materials having chemically and physically excellent properties
have been demanded in the market. Particularly in the
electric/electronic field, a highly purified resin is desired.
However, it is recently pointed out that gas (so-called "outgas"),
which is vaporized from plastic containers for housing or
transporting electric/electronic parts, damages the
electric/electronic parts housed in the containers, and that when a
resin is molded, the outgas is also generated and contaminates
molds, thereby degrading appearance of the resultant molded
articles.
[0003] Accordingly, highly purified resins such as of
polypropylene, polycarbonate and polybutylene terephthalate are
used as resins for use in forming wafer boxes used in
transportation of semiconductor wafers and so on, chip trays used
in transportation or processing of semiconductor chips, or the
like. Some resins that are easy to be electrostatically charged
often cause electrostatic trouble, and have a limitation to the
aforementioned uses.
[0004] On the other hand, styrenic resins such as ABS resins have
been widely used in the fields of electrics or electronics,
household electrical appliances and automobiles, since they are
excellent in moldability and physical and mechanical properties.
However, styrenic resins also have the above-mentioned problems of
outgas generation and electrostatic trouble.
[0005] Generally, resins contain residual impurities such as
unreacted monomers, oligomers, solvents, compounds blended as
auxiliary agents and compounds derived from the auxiliary agents.
These impurities are considered to constitute outgas. Therefore, in
order to reduce the outgas generation, it is considered that these
impurities must be removed. As methods for purifying resins by
removing impurities, various methods are known. For example,
mention may be made of a method in which volatile substances are
stripped from an aqueous dispersion of a polymer substance (see
Patent Document 7 below); a method in which monomers are vaporized
by dividing latexes into small droplets and supplying them with
steam (see Patent Document 8 below); and a method in which heat
treatment is carried out under reduced pressure to remove monomers
from latexes whilst steam is passed through a tank to form a thin
film of steam on the wall surface of the tank (see Patent Document
9 below). However, in these methods, resins are exposed to high
temperature for a long time, thereby occasionally decreasing in
quality.
[0006] On the other hand, as a method for overcoming the problem of
electrostatic trouble, kneading an antistatic agent into a resin is
generally known. However, this method has a drawback in that the
antistatic effect does not last long so that the surface
resistivity value increases with time. To improve sustainability of
the antistatic effect, a method in which a polyamide elastomer is
blended with a styrenic rein such as an ABS resin has been proposed
(see Patent Documents 2, 3, 4, and 6 below). It is also known that
lithium compounds are used as antistatic agents that can be blended
with styrenic resins to further improve antistaticity (see Patent
Documents 1 and 5 below).
[0007] Although these approaches make it possible to fairly improve
the antistaticity of styrenic resins, still higher antistaticity is
recently demanded in the electric/electronic field. In addition, a
styrenic resin highly reduced in outgas generation is also
required. This is the case for resins other than styrenic
resins.
[0008] Patent Document 1: Japanese Patent Laid-Open No.
H05-163402
[0009] Patent Document 2: Japanese Patent Laid-Open No.
H05-163441
[0010] Patent Document 3: Japanese Patent Laid-Open No.
H06-107884
[0011] Patent Document 4: Japanese Patent Laid-Open No.
H06-220274
[0012] Patent Document 5: Japanese Patent Laid-Open No.
H08-109327
[0013] Patent Document 6: Japanese Patent No. 3386612
[0014] Patent Document 7: Japanese Patent Laid-Open No.
S50-58184
[0015] Patent Document 8: Japanese Patent Publication No.
S43-6065
[0016] Patent Document 9: Japanese Patent Publication No.
S44-844
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0017] The present invention was made in view of the aforementioned
circumstances. An object of the present invention is to provide a
thermoplastic resin composition which is highly purified more than
before by removing impurities such as unreacted monomers and is
extremely small in outgas generation, and to provide a molded
article thereof.
[0018] Another object of the present invention is to provide a
thermoplastic resin composition which gives a molded article that
generates an extremely small amount of outgas and has excellent
antistaticity, abrasion resistance, impact resistance and
transparency, and provide a molded article thereof.
Means for Solving the Problems
[0019] The present inventors have conducted intensive studies to
attain the aforementioned objects. As a result, they found that
when the amount of outgas released from a thermoplastic resin
composition is 1500 .mu.g/g or less, a container for
electric/electronic parts, which has no negative effect upon
semiconductor wafers, can be provided Thus, the present invention
was accomplished.
[0020] According to an aspect of the present invention, there is
provided a thermoplastic resin composition comprising a
thermoplastic resin (A) characterized in that it has outgas in an
amount of 1500 .mu.g/g or less.
[0021] It is preferable that the thermoplastic resin composition of
the present invention further comprises a substance (B) for
reducing a surface resistivity, in an amount of 0.1 to 70 parts by
mass relative to 100 parts by mass of the thermoplastic resin
(A).
[0022] According to a preferred embodiment of the present
invention, the thermoplastic resin composition of the present
invention in which the thermoplastic resin (A) comprises a styrenic
resin.
[0023] In the present invention, it is preferable that the surface
resistivity reducing substance is a polyamide elastomer which
comprises a hard segment comprising polyamide 12 and a soft segment
comprising poly(alkylene oxide)glycol. By blending such a polyamide
elastomer with a thermoplastic resin, the thermoplastic resin can
be reduced in content of all-volatile substances to a predetermined
amount or less. As a result, the thermoplastic resin is not only
reduced in outgas generation but also remarkably improved in
antistaticity whilst being kept good in abrasion resistance, impact
resistance and transparency.
[0024] It is preferable that the polyamide elastomer mentioned
above has a refractive index of 1.5 to 1.53, a melting point of 130
to 160.degree. C., a solution viscosity of 1.35 to 1.70 and a
surface resistivity of 1.times.10.sup.8 to
1.times.10.sup.11.OMEGA..
[0025] According to another aspect of the present invention, there
is provided an antistatic agent comprising a polyamide elastomer
which comprises a hard segment comprising polyamide 12 and a soft
segment comprising poly(alkylene oxide)glycol, characterized in
that the polyamide elastomer has a refractive index of 1.5 to 1.53,
a melting point of 130 to 160.degree. C., a solution viscosity of
1.35 to 1.70 and a surface resistivity of 1.times.10.sup.8 to
1.times.10.sup.11.OMEGA..
[0026] According to still another aspect of the present invention,
there is provided a resinous molded article which is formed of the
thermoplastic resin composition according to the present invention
and has a surface resistivity of 1.times.10.sup.11.OMEGA. or
less.
[0027] It is preferable that the resinous molded article has a
taber abrasion index of less than 30.
[0028] The resinous molded article according to the present
invention is suitably used as a container that receives at least
one selected from the group consisting of a semiconductor related
component, a semiconductor related device, a liquid crystal related
component and a liquid crystal related device.
EFFECTS OF THE INVENTION
[0029] A thermoplastic resin composition according to the present
invention is highly purified and generates outgas in an amount of
1500 .mu.g/g or less. Therefore, the thermoplastic resin
composition can be preferably used as a molding material for
various types of resinous molded articles such as containers that
receive semiconductor related components and the like. The
impurities contained in the composition have little negative effect
upon the parts received in the container. In addition, since the
abrasion resistance of the container is improved, there is no
possibility that dust is generated from the container.
[0030] Furthermore, when it contains a surface resistivity reducing
substance such as a polyamide elastomer in an amount of 0.1 to 70
parts by mass relative to 100 parts by mass of the thermoplastic
resin composition such as a styrenic resin, the amount of outgas
can be easily reduced to 1500 .mu.g/g or less and further to 1000
.mu.g/g or less; at the same time, the surface resistivity value
can be reduced to 1.times.10.sup.11.OMEGA. or less. Thus,
attachment of dust and the like to resinous molded articles can be
sufficiently suppressed. Also in this case, abrasion resistance,
impact resistance and transparency can be maintained well. Hence,
thermoplastic resin compositions and resinous molded articles
suitably used in the electric/electronic field can be provided.
[0031] Also in the case where the polyamide elastomer has a
refractive index of 1.5 to 1.53, a melting point of 130 to
160.degree. C., a solution viscosity of 1.35 to 1.7 and a surface
resistivity of 1.times.10.sup.8 to 1.times.10.sup.11.OMEGA.,
attachment of dust and the like to resinous molded articles can be
sufficiently suppressed and abrasion resistance, impact resistance
and transparency can be maintained well.
[0032] Furthermore, resinous molded articles formed of the
thermoplastic resin composition according to the present invention
can be reduced in surface resistivity value as low as
1.times.10.sup.11.OMEGA. or less and thus the attachment of dust
and the like to the resinous molded articles can be sufficiently
suppressed.
[0033] Moreover, when the taber abrasion index of the resinous
molded article is less than 30, abrasion of the resinous molded
article can be suppressed even if it is moved.
[0034] In addition, when the resinous molded article is used as a
container receiving at least one of a semiconductor related
component, a semiconductor related device, a liquid crystal related
component and a liquid crystal related device, contamination of
these components and devices with outgas can be suppressed.
BEST MODE FOR CARRYING OUT THE INVENTION
[0035] The present invention will be explained in details
below.
[0036] Note that the terms "(co)polymerization" and "(co)polymer"
used herein refer to "homopolymerization" and/or "copolymerization"
and "homopolymer" and/or "copolymer", respectively. The terms
"(meth)acryl" and "(meth)acrylate" refer to "acryl" and/or
"methacryl" and "acrylate" and/or "methacrylate", respectively.
[0037] Examples of the thermoplastic resin (A) of the present
invention include, for example, styrenic resins, polyolefin resins
such as polypropylene and polyethylene, polyester resins such as
polybutylene terephthalate and polyethylene terephthalate,
polyamide resins such as nylon 6, nylon 66 and nylon 46,
polycarbonate resins, polyvinylchloride resins, polyvinylidene
chloride resins, fluorine resins, polyvinylidene fluoride polymers,
ethylene-vinyl acetate copolymers, polysulfones, polyether
sulfones, polyphenylene sulfides, liquid crystal polymers and
acylate resins. These polymers may be used singly or in combination
of two or more.
[0038] Of them, the present invention is particularly suitable for
application to a thermoplastic resin (A) containing a styrenic
resin. When the styrenic resin is blended with another type of
resin, the content of the latter resin is preferably 5 to 200 parts
by mass, and more preferably 5 to 150 parts by mass, relative to
100 parts by mass of the styrenic resin.
[0039] The styrenic resin encompasses a rubber-reinforced resin
(A1) and/or a copolymer (A2).
[0040] The rubber-reinforced resin (A1) can be obtained by
polymerizing a vinyl monomer (b) comprising an aromatic vinyl
compound and optionally another vinyl monomer copolymerizable with
the aromatic vinyl compound, in the presence of a rubber-like
polymer (a).
[0041] The copolymer (A2) can be obtained by polymerizing a vinyl
monomer (b) comprising an aromatic vinyl compound and optionally
another vinyl monomer copolymerizable with the aromatic vinyl
compound, in the absence of a rubber-like polymer (a).
[0042] Examples of the rubber-like polymer (a) include
polybutadiene, polyisoprene, butyl rubber, styrene-butadiene
copolymer (content of styrene is preferably 5 to 60% by mass),
styrene-isoprene copolymer, acrylonitrile-butadiene copolymer,
ethylene-.alpha.-olefin copolymer, ethylene-.alpha.-olefin-polyene
copolymer, silicone rubber, acrylic rubber,
butadiene-(meth)acrylate copolymer, polyisoprene, styrene-butadiene
block copolymer, styrene-isoprene block copolymer, hydrogenated
styrene-butadiene block copolymer, hydrogenated butadiene polymer,
and ethylenic ionomer. The styrene-butadiene block copolymer and
styrene-isoprene block copolymer include those having AB type, ABA
type, taper type and radial-teleblock type structures. Furthermore,
the hydrogenated butadiene polymer includes not only hydrogenated
products of the above-mentioned block copolymers but also
hydrogenated products of a Polystyrene block and a
styrene-butadiene random copolymer block, and hydrogenated products
of a polymer composed of a polybutadiene block with 1,2-vinyl bond
content of not more than 20% by mass and a polybutadiene block with
1,2-vinyl bond content of more than 20% by mass. As the rubber-like
polymer (a), polybutadiene, ethylene-.alpha.-olefin copolymer and
the like are frequently used. These rubber-like polymers (a) may be
used singly or in a combination of two or more.
[0043] When the component (a) is obtained by emulsion
polymerization, gel content of the rubber-like polymer is not
particularly limited; however, the gel content is preferably not
more than 98% by mass, and more preferably 40 to 98% by mass. If
the gel content is within this range, it is possible to obtain a
thermoplastic resin composition capable of providing molded
articles having excellent impact resistance particularly.
[0044] Note that the gel content can be obtained in the following
manner. One (1) gram of the rubber-like polymer is added to 100 ml
of toluene. The mixture is allowed to stand still at room
temperature for 48 hours, and is then filtrated through a 100-mesh
metal screen (the mass is defined as W.sub.1 g). The filtrated
insoluble matter in toluene and the metal screen are dried at
80.degree. C. for 6 hours in vacuum and weighed (the mass is
defined as W.sub.2 g). The gel content is obtained in accordance
with the following equation (1):
Gel content (% by mass)=[{W.sub.2(g)-W.sub.1(g)}/1(g)].times.100
(1)
[0045] The gel content is controlled by appropriately specifying
type and amount of a molecular-weight adjusting agent,
polymerization time, polymerization temperature and polymerization
conversion, when the rubber-like polymer is produced.
[0046] As an aromatic vinyl compound constituting the vinyl monomer
(b), mention may be made of styrene, .alpha.-methylstyrene,
p-methylstyrene, hydroxystyrene and a halogenated styrene such as
bromostyrene. These may be used singly or in combination of two or
more. Of them, styrene and .alpha.-methylstyrene are
preferable.
[0047] As the other vinyl monomer that is copolymerizable with the
aromatic vinyl compound, mention may be made of a vinyl cyanide
compound, a (meth)acrylate compound, a maleimide compound and
various other functional group containing unsaturated compounds. A
preferable vinyl monomer (b) contains an aromatic vinyl compound as
an essential monomer component, to which one or two or more types
of compounds selected from the group consisting of a vinyl cyanide
compound, a (meth)acrylate compound and a maleimide compound are
optionally added as a monomer component. Furthermore, if necessary,
at least one of the various other functional group containing
unsaturated compounds may be used together as the monomer
component. Examples of the various other functional group
containing unsaturated compounds include an unsaturated acid
compound, an epoxy group containing unsaturated compound, a hydroxy
group containing unsaturated compound, an oxazoline group
containing unsaturated compound, an acid anhydride group containing
unsaturated compound and a substituted or unsubstituted amino group
containing unsaturated compound. The various other functional group
containing unsaturated compounds mentioned above may be used singly
or in a combination of two or more.
[0048] Examples of the vinyl cyanide compound used herein include
acrylonitrile and methacrylonitrile. They may be used singly or in
combination of two or more. When a vinyl cyanide compound is used,
chemical resistance is imparted. The vinyl cyanide compound may be
used generally in an amount of 10 to 40% by mass and preferably 15
to 35% by mass relative to 100% by mass of the total of the
component (b). When a high-level chemical resistance is required,
the amount of the vinyl cyanide compound is 20 to 60% by mass and
preferably 25 to 50% by mass When outgas is desired to be
suppressed extremely low, the amount of the vinyl cyanide compound
is 0 to 15% by mass and preferably 0 to 10% by mass.
[0049] As the (meth)acrylate compound, for example, an alkyl
(meth)acrylate may be mentioned. Specific examples thereof include
acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate,
butyl acrylate, hexyl acrylate, octyl acrylate and 2-ethylhexyl
acrylate, and methacrylates such as methyl methacrylate, ethyl
methacrylate, propyl methacrylate, butyl methacrylate, hexyl
methacrylate, octyl methacrylate and 2-ethylhexyl methacrylate They
may be used singly or in a combination of two or more. Use of a
(meth)acrylate compound is advantageous in that transparency is
imparted, and surface hardness is improved. A (meth)acrylate
compound is preferably used in an amount of 1 to 93% by mass, more
preferably 2 to 85% by mass, and most preferably 5 to 80% relative
to 100% by mass of the total of the component (b). Note that, to
impart transparency, the refractive indexes of component (a) and
component (b) of Component (A1) and component (A2) are all set at
an equal or close value. For example, when a diene rubber polymer
such as polybutadiene is used as component (a), the amount of
(meth)acrylate compound is preferably 30 to 95% by mass, more
preferably 40 to 90% by mass, and most preferably 50 to 85% by mass
relative to 100% by mass of the total of the component (b).
[0050] Examples of the maleimide compound include maleimide
compounds derived from .alpha.- and .beta.-unsaturated dicarboxylic
acids such as maleimide, N-methylmaleimide, N-butylmaleimide,
N-phenylmaleimide and N-cyclohexylmaleimide. They may be used
singly or in combination of two or more. To introduce a maleimide
unit, maleic anhydride may be copolymerized and thereafter
imidized. When a maleimide compound is used, thermal resistance is
imparted. The maleimide compound is used preferably in an amount of
1 to 60% by mass, and more preferably 5 to 50% by mass relative to
100% by mass of the total of the component (b).
[0051] Examples of the unsaturated acid compound include acrylic
acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid,
itaconic acid, crotonic acid, and cinnamic acid. They may be used
singly or in combination of two or more.
[0052] Examples of the epoxy group containing unsaturated compound
include glycidyl acrylate, glycidyl methacrylate and allylglycidyl
ether. They may be used singly or in a combination of two or
more.
[0053] Examples of the hydroxy group containing unsaturated
compound include hydroxystyrene, 3-hydroxy-1-propene,
4-hydroxy-1-butene, cis-4-hydroxy-2-butene,
trans-4-hydroxy-2-butene, 3-hydroxy-2-methyl-1-propene,
2-hydroxyethylmethacrylate, 2-hydroxyethylacrylate, and
N-(4-hydroxyphenyl)maleimide. They may be used singly or in
combination of two or more.
[0054] Examples of the oxazoline group containing unsaturated
compound include vinyl oxazoline. They may be used singly or in
combination of two or more.
[0055] Examples of the acid anhydride group containing unsaturated
compound include maleic anhydride, itaconic anhydride and
citraconic anhydride. They may be used singly or in combination of
two or more.
[0056] Examples of the substituted or unsubstituted amino group
containing unsaturated compound include aminoethyl acrylate,
propylaminoethyl acrylate, aminomethyl methacrylate, aminoethyl
methacrylate, aminopropyl methacrylate, dimethylaminoethyl
methacrylate, phenylaminoethyl methacrylate, N-vinyldiethylamine,
N-acetylvinylamine, acrylamine, methacrylamine, N-methylacrylamine,
acrylamide, methacrylamide, N-methylacrylamide, p-aminostyrene and
other aminostyrenes. They may be used singly or in combination of
two or more.
[0057] When a functional group containing unsaturated compound as
mentioned above is used in a blend of a styrenic resin and another
polymer, compatibility of them can be improved. As a monomer for
attaining such an effect, mention is preferably made of an epoxy
group containing unsaturated compound, a carboxyl group containing
unsaturated compound and a hydroxy group containing unsaturated
compound, more preferably a hydroxy group containing unsaturated
compound, and most preferably 2-hydroxylethyl(meth)acrylate.
[0058] Various other functional group containing unsaturated
compounds as mentioned above are preferably used in a total amount
of 0.1 to 20% by mass, and more preferably 0.1 to 10% by mass,
relative to 100% by mass of the total of the component (b).
[0059] Amount of monomers other than the aromatic vinyl compound in
the vinyl monomer (b) is generally 98% by mass, preferably 5 to 95%
by mass, more preferably 10 to 80% by mass, further more preferably
10 to 60% by mass, and most preferably 10 to 40% by mass based on
100% by mass of the total of the vinyl monomer (b). Examples of the
combination of monomers constituting the vinyl monomer (b) include
(i) aromatic vinyl compound/vinyl cyanide compound, (ii) aromatic
vinyl compound/(meth)acrylate compound, (iii) aromatic vinyl
compound/vinyl cyanide compound/(meth)acrylate compound, (iv)
aromatic vinyl compound/maleimide compound/vinyl cyanide compound,
and (v) aromatic vinyl compound/2-hydroxylethyl(meth)acrylate/vinyl
cyanide compound. More preferable combination of monomers
constituting the vinyl monomer (b) include styrene/acrylonitrile,
styrene/methyl methacrylate, styrene/acrylonitrile/methyl
methacrylate, styrene/acrylonitrile/glycidyl methacrylate,
styrene/acrylonitrile/2-hydroxyethylmethacrylate,
styrene/acrylonitrile/(meth)acrylate, styrene/N-phenylmaleimide,
and styrene/methyl methacrylate/cyclohexylmaleimide. The most
preferable combination of monomers to be polymerized in the
presence of a rubber-like polymer (a) include styrene/acrylonitrile
in a ratio (by mass) of 65/45 to 90/10, styrene/methyl methacrylate
in a ratio (by mass) of 80/20 to 20/80,
styrene/acrylonitrile/methyl methacrylate in which the amount of
styrene falls within a range of 20 to 80% by mass, and the total of
acrylonitrile and methyl methacrylate falls within a range of 20 to
80% by mass.
[0060] The composition (A1) can be produced by a known
polymerization method such as emulsion polymerization, bulk
polymerization, solution polymerization, suspension polymerization
and a combination of these. Of them, preferable polymerization
methods for the composition (A1) include emulsion polymerization
and solution polymerization.
[0061] When the emulsion polymerization is employed, known
polymerization initiators, chain transfer agents and emulsifiers,
etc. may be used.
[0062] Examples of the polymerization initiator include cumen
hydroperoxide, p-menthane hydroperoxide, diisopropylbenzene
hydroperoxide, tetramethylbutyl hydroperoxide, tert-butyl
hydroperoxide, potassium persulfate and azobisisobutyronitrile.
[0063] Redox system is preferable as the polymerization initiator
by using various reducing agents, a sugar-containing iron
pyrophosphate formulation and a sulfoxylate formulation.
[0064] Examples of the chain transfer agent include octyl
mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-hexyl
mercaptan and terpinolene.
[0065] Examples of the emulsifier include an alkylbenzene sulfonate
such as sodium dodecylbenzene sulfonate, an aliphatic sulfonate
such as sodium lauryl sulfate, a higher aliphatic acid salt such as
potassium laurate, potassium stearate, potassium oleate and
potassium palmitate, and a rosin acid salt such as potassium
rosinate.
[0066] Note that, the emulsion polymerization may be performed by
using a rubber-like polymer (a) and a vinyl monomer (b) in the
following manner. Polymerization may be performed by adding the
vinyl monomer (b) entirely, intermittently, or continuously to the
entire amount of the rubber-like polymer (a). Alternatively, part
of the rubber-like polymer (a) may be added during a
polymerization.
[0067] After the emulsion polymerization, the obtained latex is
usually coagulated by a coagulating agent, washed with water and
dried to give a component (A1) of the present invention as powder.
In this instance, two or more types of latexes obtained by emulsion
polymerization as the component (A1) may be appropriately blended
and then coagulated. As the coagulating agent used herein, mention
may be made of an inorganic salt such as calcium chloride,
magnesium sulfate and magnesium chloride, and an acid such as
sulfuric acid, hydrochloric acid, acetic acid, citric acid and
malic acid.
[0068] The solvent that can be used in producing a component (A1)
by solution polymerization is an inert polymerization solvent
usually used in radical polymerization. Examples thereof include
aromatic hydrocarbons such as ethyl benzene and toluene, ketones
such as methylethyl ketone and acetone, acetonitrile,
dimethylformamide and N-methylpyrrolidone.
[0069] Polymerization temperature preferably falls within the range
of 80 to 140.degree. C., and more preferably 85 to 120.degree.
C.
[0070] In polymerization, a polymerization initiator may be used.
Alternatively, polymerization may be performed by thermal
polymerization without using a polymerization initiator. Preferable
examples of the polymerization initiator include organic peroxides
such as ketone peroxide, dialkyl peroxide, diacyl peroxide, peroxy
ester, hydroperoxide, azobisisobutyronitrile and benzoyl
peroxide.
[0071] When a chain transfer agent is used, mercaptans,
terpinolenes and .alpha.-methylstyrene dimers may be used.
[0072] When bulk polymerization and suspension polymerization are
employed, polymerization initiators and chain transfer agents as
explained in the section of solution polymerization may be
used.
[0073] The polymer obtained by polymerizing a vinyl monomer (b) in
the presence of a rubber-like polymer (a) generally contains
copolymers in which the vinyl monomer (b) is grafted to the
rubber-like polymer (a) and ungrafted components of vinyl monomer
(b) (i.e., (co)polymers of vinyl monomers (b), which are not
grafted to the rubber-like polymer (a)).
[0074] Graft ratio of the component (A1) is preferably 5 to 200% by
mass, more preferably 20 to 200% by mass, further more preferably
30 to 150% by mass, and most preferably 40 to 120% by mass. The
graft ratio can be obtained in accordance with the following
Equation (2).
Graft ratio (% by mass)={(T-S)/S}.times.100 (2)
[0075] In the Equation (2), T represents the mass (g) of insoluble
matter obtained by adding 1 g of a component (A1) to 20 ml of
acetone (acetonitrile is used in the case where acrylic rubber is
used as the rubber-like polymer (a)), shaking the mixture by a
shaker for 2 hours, spinning for 60 minutes by a centrifuge (at a
rotation speed of 23,000 rpm), thereby separating the insoluble
matter from soluble matter; and S represents the mass (g) of a
rubber-like polymer contained in 1 g of the component (A1).
[0076] Limiting viscosity [.eta.] of the soluble matter of the
component (A1) in acetone (acetonitrile in the case where acrylic
rubber is used as the rubber-like polymer (a)), which is measured
at 30.degree. C. using methyl ethyl ketone as a solvent, is
generally 0.2 to 1.5 dl/g, preferably 0.2 to 1.2 dl/g, further
preferably 0.2 to 1.0 dl/g, and most preferably 0.3 to 0.8
dl/g.
[0077] Average size of particles of the grafted rubber-like polymer
dispersed in the component (A1) preferably falls within the range
of 500 to 30,000 .ANG., more preferably 1,000 to 20,000 .ANG., and
most preferably 1,500 to 8,000 .ANG..
[0078] The average particle size can be determined by known
electron microscopic methods.
[0079] The amount of the rubber-like polymer (a) to be used is
generally 3 to 90% by mass, preferably 3 to 80% by mass, and from
the viewpoint of impact resistance, preferably 3 to 70% by mass,
more preferably 5 to 60% by mass, and most preferably 10 to 40% by
mass relative to 100% by mass of the entire component (A1). From
the viewpoint of impact resistance, the ratio of the rubber-like
polymer (a) to the entire thermoplastic resin composition (A)
according to the present invention is preferably 1 to 50% by mass,
more preferably 3 to 40% by mass, further more preferably 5 to 30%
by mass, and most preferably about 10 to 20% by mass relative to
100% by mass of the entire thermoplastic resin composition (A).
[0080] In the present invention, the styrenic resin may comprise
the component (A1) alone, the component (A2) alone or a mixture of
the component (A1) and the component (A2). To reduce the amount of
outgas, it is often preferred that the styrenic resin comprises the
component (A1) alone, and particularly in the case where an
aromatic vinyl compound and a (meth)acrylate compound are used in
combination as a vinyl monomer (b), the styrenic resin preferably
comprises the component (A1) alone. Even when the styrenic resin
comprises the component (A1) alone in this way, the rubber-like
polymer (a) is used in the same amount as mentioned above.
[0081] As an example of a vinyl monomer (b) constituting the
copolymer of the component (A2), mention may be made of all
compounds exemplified as the vinyl monomer (b) above, such as an
aromatic vinyl compound, a vinyl cyanide compound, a (meth)acrylate
compound, a maleimide compound and other various functional group
containing unsaturated compounds. These compounds may be used
singly or in combination of two or more. Generally, an aromatic
vinyl compound is used as an essential monomer component. In
addition to this, if necessary, one or two or more monomers
selected from the group consisting of a vinyl cyanide compound, a
(meth)acrylate compound and a maleimide compound can be used as a
monomer component in combination. Furthermore, if necessary, at
least one type of other various functional group containing
unsaturated compounds may be used as a monomer component in
combination.
[0082] When the rubber-reinforced resin is blended with another
polymer, an epoxy group containing unsaturated compound, a carboxyl
group containing unsaturated compound or a hydroxy group containing
unsaturated compound is preferably used as the functional group
containing unsaturated compound to improve compatibility of both
the rubber-reinforced resin and the polymer, and among them, the
hydroxy group containing unsaturated compound is more preferable,
and 2-hydroxylethyl(meth)acrylate is most preferable.
[0083] Preferable amount of the aromatic vinyl compound, the vinyl
cyanide compound, the (meth)acrylate compound and the maleimide
compound to be used in the component (A2) is the same as that of
the vinyl monomer (b) in the component (A1) although it may be
different.
[0084] Preferable combinations of monomers constituting the
copolymer (A2) include (i) aromatic vinyl compound/vinyl cyanide
compound, (ii) aromatic vinyl compound/alkyl (meth)acrylate, (iii)
aromatic vinyl compound/vinyl cyanide compound/alkyl
(meth)acrylate, (iv) aromatic vinyl compound/maleimide
compound/vinyl cyanide compound and (v) aromatic vinyl
compound/2-hydroxylethyl(meth)acrylate/vinyl cyanide compound.
[0085] The copolymer (A2) can be produced in the same manner as the
rubber-reinforced resin (A1) except that the vinyl monomer (b) is
polymerized in the absence of a rubber-like polymer. Preferable
polymerization methods include bulk polymerization, solution
polymerization, suspension polymerization and emulsion
polymerization.
[0086] The copolymer (A2) may be a copolymer having a single
composition or a blend of two or more copolymers different in
composition.
[0087] Intrinsic viscosity of the copolymer (A2) (measured in a
methylethyl ketone at 30.degree. C.) is generally 0.2 to 1.5,
preferably 0.3 to 1.3 dl/g, more preferably 0.4 to 1.0 dl/g, and
most preferably 0.4 to 0.8 dl/g. The intrinsic viscosity can be
controlled by chain transfer agents, polymerization time,
polymerization temperature, or the like.
[0088] The components (A1) and (A2) are used generally in the form
of powder or pellet. When the components (A1) and (A2) are used as
a mixture, methods of mixing them are not particularly limited. The
components (A1) and (A2), each of which may be in powder form or
pellet form, may be dry-blended. Furthermore, the components (A1)
and (A2), each of which may be in powder form or pellet form, may
be mixed by melt-kneading by use of a kneading roller, kneader, or
extruder. Moreover, they are dry-blended and thereafter
melt-kneaded. Note that when powders or pellets are mixed, the
following component (B), another resin or an additive such as an
antioxidant may be added. The mixing and the molding into an
article may be performed in series or performed separately in
discrete steps.
[0089] According to the present invention, the surface resistivity
of the thermoplastic resin composition can be reduced by blending a
surface resistivity reducing substance (B) with the composition. As
the surface resistivity reducing substance, mention may be made of
a polyamide elastomer, a polyester elastomer, a conductive carbon
black and a conductive carbon fiber. Note that in the cases where a
polyamide elastomer and a polyester elastomer are used, the surface
resistivity can be further reduced by adding a lithium compound
such as lithium chloride and lithium bromide. As the surface
resistivity reducing substance, a polyamide elastomer and a
polyester elastomer are preferable and a polyamide elastomer is
most preferable. These surface resistivity reducing substances may
be used singly or in a combination of two or more.
[0090] Addition amount of the surface resistivity reducing
substance (B) is generally 0.1 to 70 parts by mass, preferably 1 to
60 parts by mass, more preferably 2 to 50 parts by mass and most
preferably 5 to 40 parts by mass relative to 100 parts by mass of a
thermoplastic resin (A). When the amount of component (B) is less
than 0.1 parts by mass, the effect of reducing the surface
resistivity or antistatic performance may be insufficient. On the
other hand, when the amount exceeds 70 parts by mass, rigidity may
decrease.
[0091] As the polyamide elastomer to be used as a component (B) in
the present invention, mention is typically made of a block
copolymer comprising a hard segment (X) formed of a polyamide and a
soft segment (Y) formed of a poly(alkylene oxide)glycol.
[0092] The polyamide component to be used as the hard segment (X)
is not particularly limited and, for example, include a polyamide
generated by reaction between a diamine and a dicarboxylic acid; a
polyamide generated by ring-opening polymerization of a lactam; a
polyamide generated by reaction of an aminocarboxylic acid, a
polyamide formed by copolymerization of monomers to be used for
generation of the above polyamides; and a mixture of these
polyamides.
[0093] Examples of the polyamide generated by reaction between a
diamine and a dicarboxylic acid include polyamides generated by
reaction between an aliphatic diamine, an alicyclic diamine or an
aromatic diamine, such as ethylenediamine, tetramethylenediamine,
hexamethylenediamine, decamethylenediamine, dodecamethylenediamine,
2,3,4- or 2,4,4-trimethylhexamethylenediamine, 1,3- or
1,4-bis(aminomethyl)cyclohexane, bis(p-aminocyclohexyl)methane,
m-xylylenediamine and p-xylylenediamine, with an aliphatic
dicarboxylic acid, an alicyclic dicarboxylic acid or aromatic
dicarboxylic acid, such as adipic acid, suberic acid, sebacic acid,
cyclohexane dicarboxylic acid, terephthalic acid and isophthalic
acid. Examples of the polyamide include a nylon mn salt where a
(m+n) value is 12 or more. Specific examples thereof include nylon
6,6, nylon 6,10, nylon 6,12, nylon 11,6, nylon 11,10, nylon 12,6,
nylon 11,12, nylon 12,6, nylon 12,10, and nylon 12,12 salts.
[0094] As the polyamide generated by ring-opening polymerization of
a lactam, mention may be made of a polyamide generated by
ring-opening polymerization of a lactam having not less than 6
carbon atoms. Examples of the lactam having not less than 6 carbon
atoms include caprolactam and laurolactam.
[0095] As the polyamide generated by reaction of an aminocarboxylic
acid include a polyamide obtained by reaction of an aminocarboxylic
acid having not less than 6 carbon atoms. Examples of the
aminocarboxylic acid having not less than 6 carbon atoms include
.omega.-amino caproic acid, .omega.-aminoenan acid,
.omega.-aminocapryl acid, .omega.-aminobergon acid, .omega.-amino
capric acid, 11-aminoundecanic acid and 12-aminododecanic acid.
[0096] Molecular weight of the hard segment (X) is not particularly
limited; however preferably 500 to 10,000, in particular 500 to
5,000 in terms of number average molecular weight. Furthermore, the
hard segment (X) may be linear or branched.
[0097] In the present invention, a hard segment (X) formed of
polyamide 12 is preferably used since it not only reduces the
surface resistivity but also easily reduces harmful outgas in a
thermoplastic resin. As the hard segment (X) formed of polyamide
12, mention may be made of a polyamide derived from ring-opening
polymerization of a lactam and a polyamide derived from an
aminocarboxylic acid.
[0098] As the polyamide derived from ring-opening polymerization of
a lactam, mention may be made of a polyamide derived from
ring-opening polymerization of a lactam having 12 carbon atoms. As
the lactam having 12 carbon atoms, laurolactam may be specifically
mentioned.
[0099] As the polyamide derived from an aminocarboxylic acid,
mention may be made of a polyamide obtained by reaction of an
aminocarboxylic acid having 12 carbon atoms. As the aminocarboxylic
acid having 12 carbon atoms, mention may be made of
12-aminododecanic acid specifically.
[0100] As the poly(alkylene oxide)glycol component to be used as
the soft segment (Y), mention may be made of polyethylene glycol,
poly(l,2 or 1,3-propyleneoxide)glycol,
poly(tetramethyleneoxide)glycol, poly(hexamethyleneoxide)glycol,
polyethylene oxide, polypropylene oxide, a block or random
copolymer between ethylene oxide and propylene oxide, a block or
random copolymer between ethylene oxide and tetrahydrofuran and an
alkylene oxide adduct of a bisphenol such as bisphenol A. Of these
glycols, polyethylene glycol and ethylene oxide adducts of
bisphenols are preferable since they have excellent antistatic
properties. Note that poly(alkylene oxide)glycol may have both ends
aminated and carboxylated. The soft segment (Y) may be linear or
branched.
[0101] The hard segment (X) can be bonded with the soft segment (Y)
by ester bond or amide bond according to the end of the soft
segment (Y). During the bonding reaction, a third component such as
a dicarboxylic acid and a diamine may be used.
[0102] As the dicarboxylic acid to be used as the third component,
mention may be typically made of an aromatic, alicyclic or
aliphatic dicarboxylic acid. As the aromatic dicarboxylic acid, one
having 4 to 20 carbon atoms may be mentioned. Specific examples
thereof include terephthalic acid, isophthalic acid, phthalic acid,
naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic
acid, diphenyl-4,4-dicarboxylic acid, diphenoxyethanedicarboxylic
acid and5-sulfoisophthalic acid 5-sodium salt. Specific examples of
the alicyclic dicarboxylic acid include 1,4-cyclohexane
dicarboxylic acid, 1,2-cyclohexane dicarboxylic acid, and
dicyclohexyl-4,4-dicarboxylic acid. Specific examples of the
aliphatic dicarboxylic acid include succinic acid, oxalic acid,
adipic acid, sebacic acid and dodecane dicarboxylic acid. These may
be used singly or in a combination of two or more. Of them,
terephthalic acid, isophthalic acid, 1,4-cyclohexane dicarboxylic
acid, sebacic acid, adipic acid and dodecane dicarboxylic acid may
be particularly preferably used in view of polymerizability, hue
and physical properties.
[0103] As the diamine to be used as the third component, an
aromatic, alicyclic and aliphatic diamine may be typically used.
Specific examples of the aromatic diamine include p-phenylene
diamine, m-phenylene diamine, diaminodiphenyl ether and
diaminodiphenyl methane. Specific examples of the alicyclic diamine
include piperazine, diaminodicyclohexylmethane, and cyclohexyl
diamine. Specific examples of the aliphatic diamine include those
having 2 to 12 carbon atoms such as hexamethylene diamine, ethylene
diamine, propylene diamine and octamethylene diamine. These
diamines may be used singly or in combination of two or more of
these diamines, hexamethylene diamine is preferable.
[0104] Molecular weight of the soft segment (Y) is not particularly
limited, however preferably 200 to 20,000, more preferably 300 to
10,000, and most preferably 300 to 4,000 in terms of number average
molecular weight.
[0105] The ratio (X/Y) of the hard segment (X) to the soft segment
(Y) in a polyamide elastomer as mentioned above is generally 10/90
to 95/5, preferably 20/80 to 90/10, more preferably 30/70 to 70/30,
further more preferably 40/60 to 60/40, and most preferably 45/55
to 55/45 (% by mass). When the ratio of the hard segment is less
than 10% by mass, compatibility with the thermoplastic resin (A)
becomes poor, with the result that appearance of molded articles
may degrade and impact resistance thereof may decrease. When the
ratio exceeds 95% by mass, antistatic performance may decrease.
[0106] In consideration of antistatic performance and transparency,
refractive index of the polyamide elastomer is preferably 1.500 to
1.530 and more preferably 1.510 to 1.520. When the refractive index
is less than 1.500, antistatic performance and transparency
decrease. When the refractive index exceeds 1.530, the
compatibility with the thermoplastic resin (A) decreases, with the
result that appearance of molded articles, impact resistance, and
transparency may decrease.
[0107] Melting point of the polyamide elastomer is preferably 130
to 160.degree. C., and more preferably, 140 to 150.degree. C. In
both cases where the melting point is less than 130.degree. C. or
beyond 160.degree. C., the compatibility with the thermoplastic
resin (A) degrades, with the result that impact resistance
decreases and appearance of molded articles may degrade.
[0108] Solution viscosity of the polyamide elastomer (formic acid
is used as a solvent) is preferably 1.35 to 1.70, more preferably
1.40 to 1.60, and most preferably 1.45 to 1.55. In both cases where
the solution viscosity is less than 1.35 or beyond 1.70, the
compatibility with the thermoplastic resin (A) degrades, with the
result that impact resistance decreases and appearance of molded
articles may degrade.
[0109] Surface resistivity value of the polyamide elastomer
preferably falls within the range of 1.times.10.sup.8 to
1.times.10.sup.11.OMEGA.. When it is outside the range, it may be
difficult to obtain the surface resistivity value of the
thermoplastic resin composition according to the present
invention.
[0110] Methods of synthesizing the polyamide elastomer are not
particularly limited; however, methods disclosed in Japanese Patent
Publication No. S56-45419 and Japanese Patent Laid-Open No.
S55-133424 may be employed.
[0111] Alternatively, in accordance with the description of
Japanese Patent No. 3386612, a polyamide elastomer prepared in the
presence of a potassium compound before or during polymerization,
or before separating and recovering the elastomer after
polymerization may be used. In this case, antistatic properties of
the thermoplastic resin composition according to the present
invention can be improved without reducing impact resistance
thereof. The amount of potassium compound to be used in a polyamide
elastomer is 10 to 50,000 ppm, preferably 20 to 3,000 ppm, more
preferably 50 to 1,000 ppm in terms of potassium atom. When the
amount is less than 10 ppm, improvement of the antistatic
properties may be insufficient. On the other hand, when the amount
exceeds 50,000 ppm, surface appearance of molded articles may
degrade.
[0112] The polyamide elastomer may contain a lithium compound such
as lithium chloride and lithium bromide. In this case, surface
resistance can be further reduced. In addition to or instead of the
lithium compound, may be used at least one selected from an alkali
metal such as sodium and potassium, an alkaline earth metal such as
magnesium and calcium, organic acid salts, sulfonates, inorganic
acid salts and halides thereof. Note that these metal compounds may
be blended during or after polymerization of the polyamide
elastomer or when the thermoplastic resin composition according to
the present invention is produced.
[0113] As the polyester elastomer, mention may be made of a
polyester elastomer produced by polycondensation between a
dicarboxylic acid and a dihydroxy compound, polycondensation of an
oxycarboxylic acid, ring-opening polycondensation of a lactone
compound, and polycondensation of a mixture of these compounds. The
polyester elastomer may be a homopolyester elastomer or a
copolyester elastomer.
[0114] Examples of the dicarboxylic acid include terephthalic acid,
isophthalic acid, naphthalene dicarboxylic acid, diphenyl
dicarboxylic acid, diphenylether dicarboxylic acid, diphenylethane
dicarboxylic acid, cyclohexane dicarboxylic acid, adipic acid, and
sebacic acid, and alkyl-, alkoxy-, halogen-substituted compounds of
these dicarboxylic acids. These dicarboxylic acids may be used in a
form of a derivative that may form an ester, more specifically a
lower alcohol ester such as dimethyl ester. These carboxylic acids
may be used singly or in combination of two or more.
[0115] Examples of the dihydroxy compound include ethylene glycol,
propylene glycol, butane diol, neopentyl glycol, butene diol,
hydroquinone, resorcin, dihydroxydiphenyl ether, cyclohexane diol,
hydroquinone, resorcin, dihydroxydiphenyl ether, cyclohexane diol,
and 2,2-bis(4-hydroxyphenyl)propane, as well as polyoxyalkylene
glycol and an alkyl, alkoxy or halogen substituted compounds
thereof. These dihydroxy compounds may be used singly or in
combination of two or more.
[0116] Examples of the oxycarboxylic acid include oxybenzoic acid,
oxynaphthoic acid, diphenylene oxycarboxylic acid, and alkyl,
alkoxy or halogen substituted compounds of these oxycarboxylic
acids. These oxycarboxylic acids may be used singly or in
combination of two or more.
[0117] The thermoplastic resin composition according to the present
invention comprises at least the component (A) or the component (A)
and the component (B) and, if necessary, may be blended with
additives or the like. Examples of the additives include
antioxidants, antistatistic agents and lubricants. Each of the
components may be mixed together by melt-kneading or other methods
by use of a kneading roller, a kneader, an extruder or the
like.
[0118] The thermoplastic resin composition according to the present
invention is formed into various molded articles by a general
molding method such injection molding, sheet-extrusion,
film-extrusion, vacuum molding, deformed molding and foam molding.
Furthermore, the molded articles of the resin may be molded by
dry-blending to obtain a molding material and continuously
melt-kneading it. Alternatively, preparation of the molding
material and the molding into molded articles may be performed as
separate operations. Shape, dimension and usage of the molded
articles are not particularly limited; but the molded articles are
suitable for use in electronic materials and parts.
[0119] The thermoplastic resin composition and the molded article
thus obtained generally contain volatile components such as
unreacted monomers contained in the components (A) and (B). Outgas
is caused by such volatile components. Therefore, it is preferable
to perform treatment for vaporizing volatile components to surely
reduce the amount of outgas to 1,500 .mu.g/g or less in a
production step of the thermoplastic resin composition of the
present invention or in a molding step of a molded article. In
order to reduce the amount of outgas contained in the entire
composition, the following methods may be preferably employed in
kneading or pelleting steps:
[0120] (1) The number of degassing stages is increased in an
extruder or the like;
[0121] (2) The degree of vacuum is increased during degassing
steps; and
[0122] (3) Degassing is azeotropically performed by adding water to
the composition.
[0123] Also, the amount of outgas can be easily reduced by using,
as the component (A) and/or the component (B), compounds low in
content of low-molecular weight volatile components. As such a
component (B), mention may be made of a polyamide elastomer
comprising a hard segment formed of polyamide 12 and a soft segment
formed of poly(alkylene oxide)glycol. As such a component (A), a
styrenic resin low in acrylonitrile content may be mentioned.
[0124] In the present invention, the term "outgas" refers to the
compounds which vaporize when a test sample obtained from a
thermoplastic resin composition or a molded article is heated at
150.degree. C. for 30 minutes. Examples of such compounds include
unreacted monomers contained as impurities in molded articles or
resin compositions, oligomers derived from monomers used therein,
residual solvents and fatty acids derived from residual
emulsifiers. The "outgas" is a term generally used in the technical
field related to manufacture of semiconductors.
[0125] As the test sample, may be used a resin composition itself
in the form of pellets or the like, a molded article into which the
resin composition is formed as a test sample, a test sample cut out
from the molded article and a test sample cut out from an article
shaped into a product such as a container. In the present
invention, it is important that the amount of outgas contained in a
molded article is 1500 .mu.g/g or less. The amount of outgas
contained in a molded article formed from a thermoplastic resin
composition of the present invention is generally considered equal
to or less than that of the molding material, that is, the
thermoplastic resin composition itself. Therefore, the
thermoplastic resin composition having an outgas amount of 1500
.mu.g/g or less is useful as a molding material for obtaining the
molded article of the present invention. In either case of the
thermoplastic resin composition and the molded article according to
the present invention, the outgas amount is preferably 1000
.mu.g/g, more preferably 900 .mu.g/g or less, and most preferably
800 .mu.g/g or less.
[0126] By use of the thermoplastic resin composition of the present
invention reduced in outgas amount as a molding material,
contamination of molding machines and molds can be prevented during
molding process. In addition, it is possible to prevent
discoloration of molded articles, deterioration of physical
properties, deterioration of heat resistance and generation of
residual odor. Furthermore, when the molded article is a container
receiving semiconductor related components or the like, volatile
matter, residual odor and the like generated from the container are
reduced, and thus yield of semiconductor related components or the
like received therein can be prevented from lowering.
[0127] In the present invention, the "outgas amount" is obtained by
separating and quantifying outgas with gas chromatography/mass
spectrometry analysis. More specifically, the "outgas amount" is
the total amount of the outgas components (such as unreacted
monomers, oligomers, residual solvents) which are quantified by
mass spectrography after being separated and determined by a gas
chromatography device in a retention time of 30 minutes. Gas
chromatographic conditions employed herein are as follows:
[0128] (1) Type of column; BPX-5 (manufactured by SUPELCO)
[0129] (2) Length of column; 30 m
[0130] (3) Temperature of column; 200.degree. C. (head space purge
and trap method)
[0131] (4) Type of carrier gas; Helium gas
[0132] (5) Flow rate of carrier gas; 50 ml/minute
[0133] As to measuring apparatuses, for example, as a gas
chromatography device, a MODEL "5890 SERIES II" manufactured by
AGLIMENT may be used, and as a mass spectrography device, a MODEL
"JEOL JMS AX505W". manufactured by JEOL DATUM may be used.
[0134] As the unreacted monomer constituting outgas, mention may be
made of monomers which are used in production of a thermoplastic
resin (A) and remain unreacted. When a styrenic resin is used as
the thermoplastic resin (A), such monomers include, for example,
aromatic vinyl monomers such as styrene, .alpha.-methylstyrene,
.sigma.-methylstyrene and p-methylstyrene, vinyl cyanide monomers
such as acrylonitrile and methacrylonitrile, acrylic vinyl monomers
such as methyl acrylate, ethyl acrylate, butyl acrylate and methyl
methacrylate, and vinyl chloride. As the oligomer constituting
outgas, mention may be made of dimers, trimers and the like of
various monomers mentioned above. Furthermore, the residual solvent
constituting outgas is the solvent which is used in production of a
thermoplastic resin (A) and remains without being removed in
degassing process. Examples of such a residual solvent include
toluene, cyclohexane, pentane, butane, benzene, and ethyl chloride.
As the fatty acid derived from an emulsifier and constituting the
outgas, mention may be made of palmitic acid, oleic acid, stearic
acid, linoleic acid and lauric acid.
[0135] The compounds determined in the gas chromatography/mass
spectrography analysis in the retention time of 12 minutes mainly
include unreacted monomers and residual solvents. The unreacted
monomers and the residual solvents have low boiling points compared
to oligomers, and thus can be relatively easily removed by
degassing process and the like. The amounts of the compounds
determined herein can be easily decreased by sufficiently treating
them with degassing process. Therefore, it is desirable that the
degassing process is performed sufficiently to reduce the vaporized
amount of unreacted monomers to 800 ppm or less, preferably 600 ppm
or less, and more preferably 400 ppm or less. The total amount of
compounds measured in the retention time of 12 minutes is
preferably 800 ppm or less, more preferably 700 ppm or less, and
most preferably 600 ppm or less.
[0136] The compounds determined in the gas chromatography/mass
spectrography analysis from the retention time of 12 minutes (not
inclusive) to 20 minutes include oligomers and the like. In the
retention time thereafter, compounds having a further higher
boiling temperature, such as fatty acids, may be detected. The
total amount of compounds separated and determined in the retention
time of 20 minutes (by the time oligomers can be separated and
detected) is preferably 1200 ppm or less, more preferably 1000 ppm
or less, and most preferably 800 ppm or less. Furthermore, the
total amount of compounds in a retention time of 30 minutes (by the
time fatty acids and the like are separated and detected), that is,
the amount of outgas, is as described above.
[0137] The thermoplastic resin composition according to the present
invention and the molded article thereof each have a surface
resistivity of 1.times.10.sup.11.OMEGA. or less, preferably
1.times.10.sup.10.OMEGA. or less, more preferably 1.times.10.sup.4
to 1.times.10.sup.10.OMEGA., and most preferably 1.times.10.sup.4
to 1.times.10.sup.9.OMEGA.. When a surface resistivity falls within
this range, attachment of particles or the like can be sufficiently
prevented. In the case where semiconductor related components and
the like are transferred and processed in a clean room, and
therefore, attachment of particles or the like may not raise a
significant problem, the surface resistivity is preferably
1.times.10.sup.8 to 1.times.10.sup.11.OMEGA., and particularly
preferably 1.times.10.sup.8to 1.times.10.sup.9.OMEGA.. On the other
hand, when sufficient antistatic properties are particularly
required, the surface resistivity is preferably 1.times.10.sup.4 to
1.times.10.sup.8.OMEGA..
[0138] In the case where the resinous molded article is a container
for receiving at least one of a semiconductor related component, a
semiconductor related device, a liquid crystal related component
and a liquid crystal related device, a plurality of containers are
often stacked with each other; a lid is opened and closed when the
container has the lid,; and the container is moved on the upper
surface of a workbench formed of stainless steel or the like during
operation. When these are repeated, abrasion powder is generated
from the container, thereby degrading performance of products
received therein. For this reason, a resinous molded article
preferably has a sufficient abrasion resistance, and more
specifically, has an abrasion amount of preferably 3.0 mg or less
as measured by a receiprocating friction and wear tester on the
conditions of 2 kg load, 20 mm/second in moving speed of test
piece, and 200 times of reciprocal motion using, as a counterpart,
a sheet formed of the same resin as used in the resinous molded
article. Note that the sheet used as the counterpart may be a flat
plate. The abrasion amount is preferably 2.5 mg or less,
particularly 2.0 mg or less, and more preferably 1.5 mg or less. If
the abrasion amount of a resinous molded article is 3.0 mg or less,
it can be a resinous molded article which is excellent in abrasion
resistance and produces a less amount of abrasion powder.
[0139] The resinous molded article preferably has a predetermined
dynamic friction coefficient which is preferably 3.0 or less. The
dynamic friction coefficient is more preferably 2.0 or less,
particularly 1.0 or less, and most preferably 0.6 or less. When the
dynamic friction coefficient of a resinous molded article is 3.0 or
less, the resinous molded article can smoothly slide and easily
move on the upper surface of a workbench even when stacked with
each other, with the result that the abrasion amount can be
reduced.
[0140] Also in the case where the counterpart is a stainless-steel
board, the abrasion amount is preferably 3.0 mg or less and a
dynamic friction coefficient is preferably 3.0 or less.
[0141] The resinous molded article has a predetermined taber
abrasion index which is preferably less than 30.
[0142] The thermoplastic resin composition according to the present
invention is suitable as a molding material for a container or the
like that receives at least one of a curtain, partition, and wall
material for a clean room, a semiconductor related component, a
semiconductor related device, a liquid crystal related component
and a liquid crystal related device, whose outgas amount must be
reduced, and particularly suitable as a molding material for a
container that receives at least one of a semiconductor related
component and a semiconductor related device. Examples of the
semiconductor related component include a semiconductor wafer such
as a silicon wafer, a hard disk, a recording disk such as a
magnet-optical disk, a disk substrate, an IC chip, a display
substrate such as a glass substrate for LCD and an organic EL glass
substrate, a LCD color filer and a magnetic resistance head of a
hard disk. The semiconductor related device includes, for example,
a mask for an original picture used in lithography. The container
mentioned above may be an open container without a lid or may
consist of an openable or sealable lid and a container main body.
Shape, dimension and usage of the resinous molded article are not
particularly limited. The container main body or lid may be
provided with a reinforcement rib and a partition rib.
[0143] As this kind of containers, mention may be made of a wafer
box for housing a semiconductor wafer such as a silicon wafer and a
mask box for storing a mask for an original picture used in
lithography, which are equipped with a lid and sealable. In
addition, mention is made of a container which is composed only of
a main body without a lid such as a semiconductor tray on which a
semiconductor chip is placed. Note that a carrier or the like is
often housed or placed in these containers for immobilizing and
holding a semiconductor wafer and a semiconductor chip. It should
be understood that the carrier and the like form part of the
container. The container which is equipped with a lid and sealable
is used for transferring a semiconductor wafer and a mask for an
original picture sealingly housed therein between factories,
buildings within a factory, and manufacturing steps. The sealable
container can be used in transferring them within a clean room on
the other hand, the container which is composed only of a main body
without a lid is particularly used in transferring a semiconductor
chip within a well-equipped clean room and in processing a chip
within the container.
EXAMPLES
[0144] The present invention will be explained in details below by
way of Examples. Unless otherwise specified, the terms "part(s)"
and "%" are based on mass. Each of the physical properties shown in
the Examples was measured as described in Section (1).
(1) Measurement of Physical Properties
(1-1) Measurement of Outgas Amount
[0145] A sheet of 80.times.55.times.2.4 mm was formed by
compression molding at 210.degree. C. Test sample piece of 50 mg by
mass was cut out from the sheet and charged in a heat extraction
tube. Then, 10 mg of quartz wool treated with silane was each
charged in the tube at each side of the test piece. The heat
extraction tube was housed in a heat furnace to which helium gas
was then supplied at a rate of 50 ml/minute at room temperature
(25.degree. C.) for one minute. Subsequently, the temperature of
the furnace was increased at a rate of 60.degree. C./minute, and
maintained to be heated at 150.degree. C. for 30 minutes. In this
manner, outgas generated from the test sample piece and captured
was injected into a gas chromatography device (manufactured by
AGLIMENT, the MODEL "5890 SERIES II") through an injection port.
The outgas separated was quantified by mass spectrography device
(manufactured by JEOL DATUM, the MODEL "JEOL JMS AX505W"). Note
that the outgas amount shown in Table 1 is the total amount of
gases obtained in the retention time of 30 minutes.
(1-2) Measurement of Surface Resistivity
[0146] A disk-shaped resinous molded article of 100 mm diameter and
2 mm thickness was produced and conditioned at a temperature of
23.degree. C. and a relative humidity of 50% for 7 days.
Thereafter, the surface resistivity of the molded article was
measured by an ultra-insulation resistance meter (manufactured by
YOKOKAWA HEWLETT-PACKARD, a MODEL "4329A").
(1-3) Measurement of Abrasion Resistance (1)
[0147] A test piece of 80.times.50.times.2.4 mm was formed by
injection molding. The test piece was cut into pieces of
25.times.25 mm and adhered to four corners of the bottom of a wafer
case for an 8 inch wafer with two-sided adhesion tapes. A weight
was placed in the case such that the entire weight of the case
became 4 kg. Subsequently, the case was placed on a product shelf
(formed of stainless steel rods of .phi.3.8 mm) and a glass plate
was disposed immediately below the case at a distance of 20 cm.
After the case was repeatedly loaded and unloaded 10 times, the
particles of the abrasion powder dropped on the glass plate was
visually counted. The number of abrasion powder particles was
regarded as an abrasion amount.
(1-4) Measurement of Abrasion Resistance (2)
[0148] Abrasion resistance was determined by using a reciprocating
dynamic friction abrader, a machine of MODEL "AFT-15M" manufactured
by TOSOKU SEIMITSU KOGYOU in the manner mentioned above. As test
pieces, a sliding ring and a flat plate of 80.times.55.times.2.4
were used in accordance with JIS K7218 A. Measurement was performed
by reciprocally moving the flat plate.
(1-5) Measurement of Dynamic Friction Coefficient
[0149] A dynamic friction coefficient was measured at the same time
when the abrasion amount was measured in accordance with the above
item (1-4).
(1-6) Measurement of Transparency
[0150] A test piece of 80.times.55.times.2.4 mm was formed by
injection molding. After the test piece was conditioned at
23.degree. C. and 50% RH for 2 days, haze of the test piece was
measured by HAZE-GARD PLUS manufactured by GARDNER. The test piece
was further conditioned at 80.degree. C. and 50% RH for a day, and
then haze thereof was measured.
(1-7) Charpy Impact Strength
[0151] Charpy impact strength was evaluated in accordance with ISO
179.
(1-8) Taber Abrasion Index
[0152] Taber abrasion was measured in accordance with JIS K7204
under the conditions: an abrasion ring CS17, a load of 1000 g, and
rotation times of 1000. A taber abrasion index was obtained in
accordance with the following equation:
Taber abrasion index=(1000/rotation)xabrasion amount (mg)
(2) Production of Rubber-Reinforced Resin (A1).
(2-1) Production of Rubber-Reinforced Resin (A1-1)
[0153] To a glass flask having an internal volume of 7L and
equipped with a stirrer, ion exchanged water (100 parts), potassium
rosinate (1 part), t-dodecyl mercaptan (0.5 part), butadiene rubber
latex (40 parts in terms of solid matter), styrene (45 parts) and
acrylonitrile (15 parts) were placed. The temperature of the
mixture was increased while stirring. When the temperature reached
50.degree. C., an aqueous activating solution containing sodium
ethylenediamine tetraacetate (0.2 part), ferrous sulfate (0.01
part), sodium formaldehyde sulfoxylate 2 hydrates (0.2 part) and
ion exchanged water (10 parts) and diisopropylbenzene hydroperoxide
(0.2 part) were added to the reaction mixture and allowed to react
for 6 hours. Conversion of monomers to polymers was 96%.
Thereafter, the reaction product, namely latex, was coagulated with
an aqueous 0.5% sulfuric acid solution at 4020 C. The temperature
of the resultant slurry was increased to 90.degree. C. and
maintained for 5 minutes. Subsequently, the slurry was washed with
water and dewatered. Then, the slurry was dried at 75.degree. C.
for 24 hours to obtain a rubber-reinforced resin (A1-1) as
powder.
(2-2) Production of Rubber-Reinforced Resin (A1-2)
[0154] To a glass flask having an internal volume of 7L and
equipped with a stirrer, ion exchanged water (100 parts), potassium
rosinate (2 parts), t-dodecyl mercaptan (0.5 part), butadiene
rubber latex (30 parts in terms of solid matter), styrene (16
parts), acrylonitrile (5 parts) and methyl methacrylate (49 parts)
were placed. The temperature of the mixture was increased while
stirring. When the temperature reached 50.degree. C., an aqueous
activating solution containing sodium ethylenediamine tetraacetate
(0.2 part), ferrous sulfate (0.05 part), sodium formaldehyde
sulfoxylate 2 hydrates (0.2 part) and ion exchanged water (10
parts) and diisopropylbenzene hydroperoxide (0.2 part) were added
to the reaction mixture and allowed to react for 6 hours.
Conversion of monomers to polymers was 96%. Thereafter, a reaction
product, namely latex, was coagulated with an aqueous 0.5% sulfuric
acid solution at 40.degree. C. The temperature of the resultant
slurry was increased to 90.degree. C. and maintained for 5 minutes.
Subsequently, the slurry was washed with water and dewatered. Then,
the slurry was dried at 75.degree. C. for 24 hours to obtain a
rubber-reinforced resin (A1-2) as powder.
(2-3) Production of Rubber-Reinforced Resin (A1-3)
[0155] To a stainless steel autoclave of 20 L volume equipped with
a ribbon-form mixing blade, an auxiliary agent continuous feeder
and a thermometer, ethylene/propylene rubber (30 parts), styrene
(45 parts), acrylonitrile (25 parts) and toluene (110 parts) were
placed. The internal temperature was increased to 75.degree. C. The
content of the autoclave was stirred for one hour to obtain a
homogenous solution. Thereafter, t-butyl-peroxyisopropyl carbonate
(0.45 part) was added to the mixture and the internal temperature
was further increased to 100.degree. C. While maintaining the
temperature, the reaction was performed at a mixing blade rotation
speed of 100 rpm. Four hours after initiation of the reaction, the
internal temperature was further increased to 120.degree. C. While
maintaining the temperature, the reaction was allowed to perform
for a further 2 hours. Conversion monomers to polymers was 85%.
Then, the internal temperature was reduced to 100.degree. C.
Thereafter, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenol)-propionate
(0.2 part) was added. Subsequently, the reaction mixture was taken
out from the autoclave and subjected to vaporization with water
vapor to remove unreacted matters and solvents. The resultant
product was formed into pellets by an extruder of 40 mm in cylinder
diameter equipped with a vent to obtain a rubber-reinforced resin
(A1-3).
(2-4) Production of Rubber Reinforced Resin (A1-4)
[0156] A rubber reinforced resin (A1-4) was obtained in the same
manner as the rubber-reinforced resin (A1-1), except that the
composition formulation shown in Table 1 was used.
(3) Production of Copolymer (A2)
(3-1) Production of Copolymer (A2-1)
[0157] Two polymerization reactors each of which had an internal
volume of 7L and was equipped with a ribbon blade and a jacket were
connected and purged with nitrogen. To the first polymerization
reactor, styrene (75 parts), acrylonitrile (25 parts) and toluene
(20 parts) were successively supplied. Subsequently, a solution of
t-dodecyl mercaptan (0.1 part) serving as a molecular weight
adjusting agent in toluene (5 parts) and a solution of
1,1'-azobis(cyclohexane-1-carbonitrile) (0.1 part) serving as a
polymerization initiator in toluene (5 parts) were successively
supplied. Polymerization was performed while controlling the
temperature of the first polymerization reactor at 110.degree. C.
and an average retention time to 2 hours. Conversion to polymers
was 60%. Thereafter, by use of a pump arranged outside the first
polymerization reactor, the resultant polymer solution was
continuously taken out of the first polymerization reactor and
supplied to the second polymerization reactor in the same amount as
the total amount of the above supplied styrene, acrylonitrile,
toluene, molecular weight adjusting agent and polymerization
initiator. Polymerization was performed in the second
polymerization reactor at a polymerization temperature of
130.degree. C. for an average retention time of 2 hours. Conversion
to polymers was 80%. Then, the polymer solution was taken out of
the second polymerization reactor and directly supplied to a
double-screw extruder with triple vents so as to remove unreacted
monomers and solvents to obtain a copolymer
(A2-1). Limiting viscosity [.eta.] of acetone-soluble matter of the
copolymer (A2-1) was 0.48 dl/g.
(3-2) Production of Copolymer (A2-2)
[0158] Two polymerization reactors each of which had an internal
volume of 30L and was equipped with a ribbon blade and a jacket
were connected and purged with nitrogen. To the first
polymerization reactor, styrene (21 parts), acrylonitrile (7
parts), methyl methacrylate (72 parts) and toluene (20 parts) were
successively supplied. Subsequently, a solution of t-dodecyl
mercaptan (0.1 part) serving as a molecular weight adjusting agent
in toluene (5 parts) and a solution of
1,1'-azobis(cyclohexane-1-carbonitrile) (0.1 part) serving as a
polymerization initiator in toluene (5 parts) were successively
supplied. Polymerization was performed while controlling the
temperature of the first polymerization reactor at 110.degree. C.
and an average retention time to.2 hours. Conversion to polymers
was 60%. Thereafter, by use of a pump arranged outside the first
polymerization reactor, the resultant polymer solution was
continuously taken out of the first polymerization reactor and
supplied to the second polymerization reactor in the same amount as
the total amount of the above supplied styrene, acrylonitrile,
methyl methacrylate, toluene, molecular weight adjusting agent and
polymerization initiator. Polymerization was performed in the
second polymerization reactor at a polymerization temperature of
130.degree. C. for an average retention time of 2 hours. Conversion
to polymers was 80%. Then, the polymer solution was taken out of
the second polymerization reactor and directly supplied to a
double-screw extruder with triple vents so as to remove unreacted
monomers and solvents to obtain a copolymer
(A2-2). Limiting Viscosity [.eta.] of Acetone-Soluble Matter of the
Copolymer (A2-2) was 0.25 dl/g.
(3-3) Production of a Copolymer (A2-3)
[0159] To a glass flask having an internal volume of 7L and
equipped with a stirrer, ion exchanged water (100 parts), sodium
dodecylbenzene sulfonate (2.5 parts), t-dodecyl mercaptan (0.1
part), styrene (22.5 parts), acrylonitrile (7.5 parts) and
hydroxyethyl methacrylate (3.3 parts) were placed. The temperature
of the flask was increased while stirring. When the temperature
reached 50.degree. C., an aqueous solution containing potassium
persulfate. (0.1 part) and ion exchanged water (5 parts) was added
to the flask and a reaction was performed for 2 hours. Thereafter,
an aqueous solution containing styrene (22.5 parts), acrylonitrile
(7.5 parts), hydroxyethyl methacrylate (3.3 parts), potassium
persulfate (0.1 part) and ion exchange water (5 parts) was added
thereto and a reaction was performed for 2 hours.
[0160] Further, an aqueous solution containing styrene (22.5
parts), acrylonitrile (7.5 parts), hydroxyethyl methacrylate (3.4
parts), potassium persulfate (0.1 part) and ion exchange water (5
parts) was added thereto and a reaction was performed for 3
hours.
[0161] Conversion of monomers to polymers was 98%. Thereafter, a
reaction product, namely latex, was coagulated with a 10% aqueous
solution of calcium chloride at 40.degree. C. The temperature of
the resultant slurry was increased to 90.degree. C. and maintained
for 5 minutes. Then, the slurry was washed with water, dewatered
and dried at 75.degree. C. for 24 hours to obtain a polymer (A2-3)
as powder.
[0162] The mass ratio of the rubber-like polymers and vinyl
monomers used in production of the rubber-reinforced resins (A1-1)
to (A1-4) and the copolymers (A2-1) to (A1-3) are shown in Table
1.
TABLE-US-00001 TABLE 1 A1-1 A1-2 A1-3 A1-4 A2-1 A2-2 A2-3 Emulsion-
40 30 -- 18 -- -- -- polymerized polybutadiene Ethylene/propylene
-- -- 30 -- -- -- -- rubber Styrene 45 16 45 20 75 21 67.5
Acrylonitrile 15 5 25 -- 25 7 22.5 Methyl -- 49 -- 62 -- 72 --
methacrylate Hydroxyethyl -- -- -- -- -- -- 10 methacrylate
(4) Polyamide Elastomer (Component (B))
[0163] A polyamide elastomer (PA12 polyamide elastomer) made of a
hard segment of polyamide 12 and a soft segment of poly(alkylene
oxide)glycol was used, which had a refraction index of 1. 514, a
melting point of 148.degree. C., a solution viscosity of 1.51, and
a surface resistivity value of 3.times.10.sup.10.OMEGA..
[0164] A polyamide elastomer (PA6 polyamide elastomer) made of a
hard segment of a polyamide 6 and a soft segment of poly(alkylene
oxide)glycol was used, which had a refraction index of 1.514, a
melting point of 195.degree. C., a solution viscosity of 1.51, and
a surface resistivity value of 4.times.10.sup.10.OMEGA..
(5) Examples I-1 to I-8 and Comparative Examples I-1 to I-7
(Preparation and Evaluation of Molding Materials)
[0165] In Examples I-1 to I-8, the rubber-reinforced resins (A1-1)
to (A1-3), the copolymers (A2-1) to (A2-2), and the polyamide
elastomers (Examples I-4 to I-6 and I-8 and Comparative Examples
I-4 to I-6) or a conductive carbon (Example I-7 and Comparative
Example I-7) serving as surface resistivity reducing substances
were dry-blended by a corn blender in accordance with the mass
ratios shown in Table 2. Thereafter, each of the mixtures was
kneaded to obtain pellets in an extruder having a cylinder of 40 mm
diameter and equipped with triple vents with addition of water (1
part) by a double Dulmage screw at a cylinder temperature of
220.degree. C. while degassing was performed under the degree of
vacuum shown in Table 2. On the other hand, in Comparative Examples
I-1 to I-7, the raw materials were dry-blended by a corn blender in
accordance with the mass ratios shown in Table 3. Thereafter, each
of the mixtures was kneaded to obtain pellets in an extruder having
a cylinder of 40 mm diameter and equipped with a single vent with
or without addition of water (1 part) by a screw having no Dulmage
portion at a cylinder temperature of 220.degree. C. while degassing
was performed under the degree of vacuum shown in Table 3.
[0166] Examples I-1, I-4 and I-7 and Comparative Examples I-1, I-4
and I-7 Relate to ABS Resins. Examples I-2 and I-5 and Comparative
Examples I-2 and I-5 relate to transparent ABS resins. Examples I-3
and I-6 and Comparative Examples I-3 and I-6 relate to AES resins.
Example I-8 relates to a styrenic resin which was not
rubber-reinforced. Resin pellets obtained in these Examples and
Comparative Examples were analyzed for the physical properties
mentioned above. The results are shown in Tables 2 and 3.
TABLE-US-00002 TABLE 2 Example I-1 I-2 I-3 I-4 I-5 I-6 I-7 I-8
Formulation Component A A1-1 40 -- -- 32 -- -- 35 -- (parts) A1-2
-- 40 -- -- 32 -- -- -- A1-3 -- -- 40 -- -- 32 -- -- A1-4 -- -- --
-- -- -- -- -- A2-1 60 -- 60 48 -- 48 55 -- A2-2 -- 60 -- -- 48 --
-- 80 A2-3 -- -- -- -- -- -- -- -- Component B PA12 polyamide -- --
-- 20 20 20 -- 20 elastomer PA6 polyamide -- -- -- -- -- -- -- --
elastomer Conductive carbon -- -- -- -- -- -- 10 -- Content (parts)
relative 0 0 0 25 25 25 11.1 25 to Component A (100 parts) Process
Degassing method TV&DD TV&DD TV&DD TV&DD TV&DD
TV&DD TV&DD TV&DD condition Degree of vacuum (kPa) 80
95 95 95 95 95 95 95 Addition of water (addition Added Added Added
Added Added Added Added Added amount: 1 part) Property Outgas
amount (.mu.g/g) 980 1050 950 800 650 950 830 780 Surface
resistivity (.OMEGA.) -- -- -- 5 .times. 10.sup.9 6 .times.
10.sup.9 6 .times. 10.sup.9 5 .times. 10.sup.8 5 .times. 10.sup.9
Abrasion resistance (2) (mg) 0.2 0.2 0.1 0.4 0.4 0.1 0.5 0.4
Dynamic friction coefficient 0.60 0.57 0.54 0.67 0.60 0.51 0.81
0.75 Haze (%) t-2.4 mm ordinary -- 5 -- -- 12 -- -- -- temperature
Taber abrasion index 29 28 29 19 18 20 31 19 In the Table, TV
denotes triple vents, and DD denotes double Dulmage.
TABLE-US-00003 TABLE 3 Comparative Example I-1 I-2 I-3 I-4 I-5 I-6
I-7 Formulation Component A A1-1 40 -- -- 32 -- -- 35 (parts) A1-2
-- 40 -- -- 32 -- -- A1-3 -- -- 40 -- -- 32 -- A1-4 -- -- -- -- --
-- -- A2-1 60 -- 60 48 -- 48 55 A2-2 -- 60 -- -- 48 -- -- A2-3 --
-- -- -- -- -- -- Component B PA12 polyamide elastomer -- -- -- 20
20 20 -- PA6 polyamide elastomer -- -- -- -- -- -- -- Conductive
carbon -- -- -- -- -- -- 10 Content (parts) relative to 0 0 0 25 25
25 11.1 Component A (100 parts) Process Degassing method SV SV SV
SV SV SV SV condition Degree of vacuum (kPa) 0 0 80 80 80 80 80
Addition of water (addition Not added Not added Not added Not added
Added Added Added amount: 1 part) Property Outgas amount (.mu.g/g)
3800 3650 3050 2850 2500 2650 2600 Surface resistivity (.OMEGA.) --
-- -- 8 .times. 10.sup.9 9 .times. 10.sup.9 9 .times. 10.sup.9 8
.times. 10.sup.6 Abrasion resistance (2)(mg) 3.2 2.8 0.3 0.8 0.9
0.4 3.1 Dynamic friction coefficient 3.1 2.5 0.85 1.2 1.5 0.95 3.5
Haze(%) t-2.4 mm ordinary -- 9 -- -- 17 -- -- temperature Taber
abrasion index 28 28 29 19 20 18 30 In the Table, SV denotes a
single vent.
[0167] According to Table 2, in Examples I-1 to I-8, the outgas
amounts were 1050 ppm or less, abrasion amounts were as low as 0.5
mg or less, dynamic friction coefficients were 0.81 or less and
taber abrasion indexes were 31 or less. From these, it is
demonstrated that the products are useful as containers for
semiconductor related components and the like. In addition, since a
surface resistivity reducing substance was added, the surface
resistivities were as low as 6.times.10.sup.9 or less. It is
demonstrated that the products also have excellent antistaticity.
On the other hand, according to Table 3, in Comparative Examples
I-I to I-7, the outgas amounts were 2500 ppm or more, which mean
that a large amount of impurities are contained. The abrasion
amount, dynamic friction coefficient and taber abrasion index were
not extremely low but insufficient compared to the Examples. Even
if a surface resistivity reducing substance was added thereto in
the same amount as in the Examples, the surface resistivity was
slightly high.
(6) Manufacture of Wafer Boxes and Wafer Trays and Evaluation
Thereof
[0168] A wafer box 1 shown in FIG. 1 and a wafer tray 13 shown in
FIG. 2 were prepared using each of the ABS resins obtained in
Example I-1 and Comparative Example I-1 by an injection-molding
machine at a mold temperature of 50.degree. C. The wafer box 1 can
house 25 sheets of wafer of 8-inch diameter. Furthermore, the wafer
box 1 houses the wafer tray 13 shown in FIG. 2. The wafer tray is
provided on the inner surface of the lateral walls with an opposed
pair of 26 ribs 131 protruding from the wall, so that semiconductor
wafers can be immobilized by the ribs.
[0169] Twenty-five (25) sheets of 8-inch silicon wafer were housed
in each of the wafer trays that were prepared from the ABS resins
of Examples I-1 and Comparative Example I-1 respectively. The wafer
trays were housed in the respective wafer boxes, which were covered
airtight with lids. The wafer boxes were allowed to stand still at
85.degree. C. for 25 hours. Thereafter, a circuit was printed on
each of the silicon wafers to prepare chips, which were evaluated
for function. As a result, all chips formed of the silicon wafers
housed in the wafer box formed of the ABS resin according to
Example I-1 showed no malfunction. On the other hand, chips formed
of the silicon wafers housed in the wafer box formed of the ABS
resin according to Comparative Example I-1 showed malfunction.
(7) Examples II-1 to II-12 and Comparative Example II-1 to II-6
(Preparation of Molding Materials and Evaluation Thereof)
[0170] In Examples II-1 to II-10, the rubber reinforced resins
(A1-1) to (A1-3), the copolymers (A2-1) to (A2-3) and the polyamide
elastomers (Example II-1 to II-10) serving as surface resistivity
reducing substances were dry-blended by a corn blender in
accordance with the formulations shown in Table 4. Thereafter, each
of the mixtures was kneaded to obtain pellets in an extruder having
a cylinder of 40 mm diameter and equipped with triple vents by a
double Dulmage screw at a cylinder temperature of 220.degree. C.
under the processing, conditions shown in Table 4 (degassing
method, degree of vacuum, and addition of water (1 part)). In
Examples II-11 to II-12, pellets were obtained in the same manner
as above except that the rubber-reinforced resin (A1-4) was
employed together with a polyamide elastomer that serves as a
surface resistivity reducing substance.
[0171] In Comparative Examples II-1 to II-6, the rubber reinforced
resins (A1-1) to (A1-3), the copolymers (A2-1) to (A2-3) and the
polyamide elastomers (Comparative Examples II-2 to II-6) serving as
surface resistivity reducing substances were dry-blended by a cone
blender in accordance with the formulations shown in Table 5.
Thereafter, each of the mixtures was kneaded to obtain pellets
under the processing conditions shown in Table 5 (degassing method,
degree of vacuum, and addition of water (1 part)).
[0172] The obtained pellets were evaluated for the physical
properties. The results are shown in Tables 4 and 5.
TABLE-US-00004 TABLE 4 Example II-1 II-2 II-3 II-4 II-5 II-6
Formulation Component A A1-1 40 40 -- -- -- -- (parts) A1-2 -- --
40 40 35 35 A1-3 -- -- -- -- -- -- A1-4 -- -- -- -- -- -- A2-1 40
35 -- -- -- -- A2-2 -- -- 40 35 53 35 A2-3 -- 5 -- 5 -- 5 Component
B PA12 polyamide 20 20 20 20 12 25 elastomer PA6 polyamide -- -- --
-- -- -- elastomer Content (parts) 25 25 25 25 13.6 33.3 relative
to Component A (100 parts) Process Degassing method TV&DD
TV&DD TV&DD TV&DD TV&DD TV&DD condition Degree
of vacuum (kPa) 80 95 95 95 95 90 Addition of water Added Added
Added Added Added Added (addition amount: 1 part) Property Outgas
amount (.mu.g/g) 850 750 650 700 700 800 Surface resistivity 5.0
.times. 10.sup.10 6.0 .times. 10.sup.9 7.0 .times. 10.sup.9 1.0
.times. 10.sup.10 8.0 .times. 10.sup.10 5.0 .times. 10.sup.9
(.OMEGA.) Abrasion resistance (1) 0 1 0 0 1 0 (number of particles)
Haze(%) t = 2.4 mm -- -- 6 9 7 10 ordinary temperature Haze(%)
t-2.4 mm after -- -- 6 10 7 11 conditioned at 80.degree. C. Charpy
impact strength 20 18 22 20 22 19 (kJ/m.sup.2) Taber abrasion index
18 16 18 19 20 18 Example II-7 II-8 II-9 II-10 II-11 II-12
Formulation Component A A1-1 -- -- -- -- -- -- (parts) A1-2 -- --
-- 40 -- -- A1-3 35 35 -- -- -- -- A1-4 -- -- -- -- 80 80 A2-1 --
-- -- 35 -- -- A2-2 45 40 80 -- -- -- A2-3 -- 5 -- -- -- --
Component B PA12 polyamide 20 20 20 25 20 -- elastomer PA6
polyamide -- -- -- -- -- 20 elastomer Content (parts) 25 25 25 33.3
25 25 relative to Component A (100 parts) Process Degassing method
TV&DD TV&DD TV&DD TV&DD TV&DD TV&DD
condition Degree of vacuum (kPa) 95 95 95 95 95 95 Addition of
water Added Added Added Added Added Added (addition amount: 1 part)
Property Outgas amount (.mu.g/g) 650 720 610 700 500 1350 Surface
resistivity 1.0 .times. 10.sup.10 8.0 .times. 10.sup.9 7.5 .times.
10.sup.9 6.0 .times. 10.sup.8 7.0 .times. 10.sup.9 8.0 .times.
10.sup.9 (.OMEGA.) Abrasion resistance (1) 0 0 2 0 0 0 (number of
particles) Haze(%) t = 2.4 mm 12 15 9 11 11 10 ordinary temperature
Haze(%) t-2.4 mm after 12 15 10 13 13 12 conditioned at 80.degree.
C. Charpy impact strength 20 20 5 21 20 18 (kJ/m.sup.2) Taber
abrasion index 17 16 16 17 16 18 In the Table, TV denotes triple
vents, and DD denotes double Dulmage.
TABLE-US-00005 TABLE 5 Comparative Example II-1 II-2 II-3 II-4 II-5
II-6 Formulation Component A A1-1 40 -- -- -- -- -- (parts) A1-2 --
30 40 -- -- -- A1-3 -- -- -- 35 35 -- A1-4 -- -- -- -- -- -- A2-1
60 -- -- -- -- -- A2-2 -- 25 40 45 40 80 A2-3 -- -- -- -- 5 --
Component B PA12 polyamide elastomer -- 45 -- -- PA6 polyamide
elastomer -- -- 20 20 20 20 Content (parts) relative to 0 81.8 25
25 25 25 Component A (100 parts) Process Degassing method SV
TV&DD SV SV SV SV condition Degree of vacuum (kPa) 80 95 90 95
95 90 Addition of water (addition amount: Added Added Added Added
Added Added 1 part) Property Outgas amount (.mu.g/g) 2400 2500 3800
2750 1800 1750 Surface resistivity (.OMEGA.) 10.sup.13 or 3.0
.times. 10.sup.9 8.0 .times. 10.sup.9 1.1 .times. 10.sup.10 8.3
.times. 10.sup.10 8.0 .times. 10.sup.9 more Abrasion resistance (1)
75 100 10 5 20 20 (number of particles) Haze (%) t = 2.4 mm
ordinary -- 20 10 13 15 12 temperature Haze (%) t = 2.4 mm after
conditioned -- 22 25 28 28 19 at 80.degree. C. Charpy impact
strength (kJ/m.sup.2) 10 14 13 12 12 1 Taber abrasion index 29 35
28 26 30 30 In the Table, SV denotes a single vent. In the Table,
TV denotes triple vents and DD denotes double Dulmage.
[0173] According to Table 4, in Examples II-1 to II-12, the outgas
amounts were 1500 .mu.g/g or less, surface resistivity values were
1.times.10.sup.11.OMEGA. or less. From these, it is demonstrated
that the molding materials are reduced in outgas generation and has
excellent antistaticity, abrasion resistance and impact resistance,
and thus useful as containers for semiconductor related components
and the like. In addition, according to Examples II-3 to II-12, the
obtained molded articles were excellent in transparency. Thus, the
products of Examples above are suitable as molding materials for
transparent containers. On the other hand, according to Table 5,
Comparative Example II-1, in which no polyamide elastomer was used
and degassing was not sufficiently performed, was inferior in
outgas amount, surface resistivity, abrasion resistance and impact
resistance. Comparative Example II-2, in which the amount of PA12
polyamide elastomer was beyond the range of the present invention,
was inferior in outgas amount, abrasion resistance, transparency
and impact resistance. Comparative Examples II-3 to II-6, in which
PA6 polyamide elastomer was used and degassing was not performed
sufficiently, were inferior in outgas amount, abrasion resistance,
impact resistance and transparency.
INDUSTRIAL APPLICABILITY
[0174] The thermoplastic resin composition according to the present
invention produces a small amount of outgas and has excellent
antistaticity, and can provide molded articles excellent in
transparency, abrasion resistance and impact resistance, and thus
is useful for various applications in the electric/electronic
fields. In particular, the thermoplastic resin composition of the
present invention can be used as molding materials for resinous
molded articles such as containers housing semiconductor related
components such as semiconductor wafers, semiconductor related
devices, liquid crystal related components and liquid crystal
related devices, more specifically, wafer boxes, chip trays, and
mask cases.
BRIEF DESCRIPTION OF THE DRAWINGS
[0175] FIG. 1 is a perspective view showing appearance of a wafer
box which is a specific example of a resinous molded article;
and
[0176] FIG. 2 is a perspective view showing a wafer tray to be
housed in the wafer box of FIG. 1.
DESCRIPTION OF SYMBOLS
[0177] In the drawings, reference symbol 1 indicates a wafer box,
11 a lid, 12 a container main body, 13 wafer tray and 131 rib.
* * * * *