Compositions – Liquid crystal compositions
Reexamination Certificate
1999-10-19
2002-04-23
Wu, Shean C. (Department: 1756)
Compositions
Liquid crystal compositions
C264S030000, C264S234000, C428S480000, C428S483000, C428S913000, C524S540000, C524S755000, C524S757000
Reexamination Certificate
active
06375863
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thermoplastic resin composition which exhibits improved flowability and metering stability at the time of molding and yields molded articles having improved impact resistance, heat resistance, chemical resistance, fatigue properties, and anisotropy. The present invention relates also to a process for production of said resin composition and a molded article of said resin composition.
2. Description of Related Arts
There are a variety of thermoplastic resins, such as polystyrene, polycarbonate, and polyphenylene ether, which find general use as an injection molding material for machine parts, electric and electronic parts, and automotive parts because of their outstanding characteristic properties. The recent advance in technology demands molded articles with intricate shapes and hence demands resin compositions with improved flowability.
One way to improve the flowability and mechanical properties of thermoplastic resins is by alloying with an optically anisotropic liquid crystalline polymer which is characterized by a parallel arrangement of molecular chains. Several alloying technologies have been disclosed in Japanese Patent Laid-open Nos. 102257/1990, 47861/1991, 70700/1993, 112709/1993, 200129/1994, 331051/1995, and 12744/1997. Their disclosures are outlined below.
Japanese Patent Laid-open Nos. 102257/1990 and 47861/1991 disclose a thermoplastic resin composition which is incorporated with a liquid crystalline polymer having an adequately low heat distortion temperature so as to improve mechanical properties, heat resistance, and dimensional stability.
Japanese Patent Laid-open No. 70700/1993 discloses a thermoplastic resin composition consisting of a liquid crystalline polymer and a thermoplastic resin capable of molding at a temperature lower than the temperature at which the liquid crystalline polymer begins to flow under stress, said resin composition exhibiting improved physical properties when stretched owing to the orientation of the dispersed particles of the liquid crystalline polymer.
Japanese Patent Laid-open No. 112709/1993 discloses a molding resin composition consisting of polycarbonate resin (as the matrix resin) and a liquid crystalline polymer having a melting point higher than that of polycarbonate resin, said resin composition yielding molded articles with a minimum of loss in strength and stiffness after recycling, owing to the orientation of the dispersed particles of the liquid crystalline polymer.
Japanese Patent Laid-open No. 200129/1994 discloses a thermoplastic resin composition consisting of a polycarbonate resin having many terminal phenolic hydroxyl groups and a liquid crystalline polymer, said resin composition having improved delamination resistance owing to the mutual action of the two components.
Japanese Patent Laid-open No. 331051/1995 discloses a thermoplastic resin composition which consists of a polycarbonate resin having many terminal phenolic hydroxyl groups, a flame retardant, and a liquid crystalline polymer, said resin composition having improved flame retardance.
Japanese Patent Laid-open No. 12744/1997 discloses a film formed from a liquid crystalline polyester resin composition in which the liquid crystalline polymer incorporated therein constitutes a continuous phase.
The above-mentioned resin compositions certainly contribute to strength and stiffness; however, they still have their respective disadvantages as follows.
Japanese Patent Laid-open Nos. 200129/1994 and 331051/1995. The resin composition is inferior in impact resistance, flowability, and chemical resistance to the polycarbonate used alone because the polycarbonate, which has many terminal phenolic hydroxyl groups, reacts strongly with the liquid crystalline polymer, thereby weakening its effect and giving rise to fine dispersed particles.
Japanese Patent Laid-open Nos. 70700/1993 and 112709/1993. The resin composition is poor in chemical resistance and heat resistance, despite slight improvement in mechanical properties, because the polycarbonate resin is denatured during melt-mixing. This denaturation is due to the fact that the polycarbonate resin and the liquid crystalline polymer are heated once for melt-mixing at a temperature higher than the melting point of the liquid crystalline polymer, so that the particles of the liquid crystalline resin are oriented. Melt-mixing in this way brings about excessive reactions between the components. Good chemical resistance is essential for the resin composition to be used for machine parts, automotive parts, and electric and electronic parts, which are exposed to oils (engine oil, brake oil, gear oil, etc.), chemicals (window washer, battery liquid, etc.), and washing agents and organic solvents (used during processing).
Japanese Patent Laid-open Nos. 112709/1993, 102257/1990, 47861/1991, and 12744/1997. The resin composition is poor in flowability and chemical resistance because of excess reactions between the thermoplastic resin and the liquid crystalline polymer. Such reactions take place when melt-mixing is carried out at a temperature higher than the melting point of the liquid crystalline polymer.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a thermoplastic resin composition which exhibits good flowability and metering stability at the time of molding. It is another object of the present invention to provide a molded article of said resin composition which has improved impact resistance, heat resistance, chemical resistance, fatigue properties, and anisotropy. The present invention covers a thermoplastic resin composition as follows.
(1) A thermoplastic resin composition which comprises 100 parts by weight of thermoplastic resin as component (A) which is at least one species selected from styrene resin, polycarbonate resin, and polyphenylene ether resin, and 0.5-100 parts by weight of liquid crystalline polymer as component (B), said thermoplastic resin as component (A) having a glass transition point the rate of change of which satisfies the equation (1) below.
Rate of change (%)=|(Tg
A
−Tg
T
)/Tg
A
|×100≦5 (1)
where Tg
A
is the glass transition point of the thermoplastic resin as component (A), and Tg
T
is the glass transition point attributable to the thermoplastic resin as component (A) in the resin composition.
Rate of change (%)=|(Tg
A
−Tg
T
)/Tg
A
|×100≦5 (1)
where Tg
A
is the glass transition point of the thermoplastic resin as component (A), and Tg
T
is the glass transition point attributable to the thermoplastic resin as component (A) in the resin composition.
The preferred embodiments of the present invention are given below.
(2) A thermoplastic resin composition as defined in paragraph (1) above, which contains the liquid crystalline polymer dispersed therein in the form of particles having a number-average particle diameter of 0.5-5 &mgr;m.
(3) A thermoplastic resin composition as defined in paragraph (1) or (2) above, which contains the liquid crystalline polymer dispersed therein in the form of particles having an aspect ratio (major axis/minor axis) smaller than 3.
(4) A thermoplastic resin composition as defined in any of paragraphs (1) to (3) above, in which the thermoplastic resin as component (A) includes a polycarbonate resin characterized by its ratio (E
P
)/(E
N
) smaller than {fraction (1/20)}, where E
P
and E
N
denote the respective amounts (in equivalent) of phenolic terminal groups and non-phenolic terminal groups in the polycarbonate resin.
(5) A thermoplastic resin composition as defined in any of paragraphs (1) to (4) above, wherein the liquid crystalline polymer as component (B) is a liquid crystalline polyester composed of the structural units represented by the formulas (I), (II), (III), and (IV) below.
where R
1
is one or more groups selected from
and R
2
is one or more groups selected from
X denotes a hydrogen atom or chlorine atom.
(6) A thermoplastic res
Makabe Yoshiki
Tachikawa Kouji
Umetsu Hideyuki
Schnader Harrison Segal & Lewis LLP
Toray Industries Inc.
Wu Shean C.
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