Compositions – Liquid crystal compositions
Reexamination Certificate
2000-05-10
2002-08-13
Wu, Shean C. (Department: 1756)
Compositions
Liquid crystal compositions
C524S495000, C428S297400
Reexamination Certificate
active
06432323
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal polyester resin composition. More specifically, the present invention relates to a liquid crystal polyester resin composition which is prepared by compounding carbon fiber which has been surface-treated with an urethane resin.
2. Description of the Related Art
A liquid crystal polyester resin (hereinafter, referred to as liquid crystal polyester) which manifests liquid crystal property in melting is excellent in heat-resistance, and is excellent in flowability, namely processability in melting, therefore, the liquid crystal polyester is used, as a molding material.which can provide precise molding, in various fields typically including electric and electronic fields. Particularly, a resin composition obtained by filling a fibrous reinforcing material such as carbon fiber or the like which has been surface-treated with an urethane resin, into a liquid crystal polyester resin is a material suitable for electric and electronic parts having thin parts or complicated forms.
However, since this resin composition has a high processing temperature, there may sometimes occur deterioration and decomposition of the resin composition due to heat, further, generation of a decomposed gas, for example, in a melt-extrusion for obtaining a resin composition in the form of pellets to be subjected to injection molding, or in a injection-molding process of a resin composition. Since a part of deteriorated materials such as gasses and the like in processing is embedded in a molded article, when the molded article is used as parts, various problems, for example, blister due to generation of a gas in a solder process, may occur.
SUMMARY OF THE INVENTION
The object of the present invention is to solve the above-described problems and provide a carbon fiber-compounded liquid crystal polyester resin composition having excellent mechanical property and heat-resistance, particularly, soldering resistance, and a molded article obtained by using the same.
That is, the present inventions is a liquid crystal polyester resin composition comprising a liquid crystal polyester resin and surface-treated carbon fiber with an urethane resin, wherein the amount of an urethane resin on the carbon fiber is from 0.5 to 5% by weight, and a molded article obtained by using the same.
The liquid crystal polyester resin composition of the invention can be prepared by compounding carbon fiber which has been surface-treated with an urethane resin in an amount of from 0.5 to 5% by weight, into a liquid crystal polyester resin.
DETAILED DESCRIPTION OF THE INVENTION
As the liquid crystal polyester resin to be used in the present invention, exemplified are:
(1) Polyesters composed of a combination of an aromatic dicarboxylic acid, aromatic diol and aromatic. hydroxycarboxylic acid,
(2) Polyesters composed of different aromatic hydroxycarboxylic acid,
(3) Polyesters composed of a combination of an aromatic dicarboxylic acid and aromatic diol,
(4) Polyesters obtained by reacting a polyester such as polyethylene terephthalate and the like with an aromatic hydroxycarboxylic acid,
and the like, and those forming isotropic melted bodies at temperatures of not more than 400° C. are preferable from the standpoint of molding processing, and the like. Further, instead of the above-described aromatic dicarboxylic acid, aromatic diol and aromatic hydroxycarboxylic acid, ester-forming derivatives thereof may also be used
As the repeating structure unit of the liquid crystal polyester include, the following structure units may be exemplified.
Repeating structure units derived from aromatic hydroxycarboxylic acids:
Repeating structure. units derived from aromatic dicarboxylic acids:
Repeating structure units derived from aromatic diols:
In the definition of the above substituents X
1
to X
3
, “H” is a hydrogen atom, “alkyl” is preferably an alkyl group having 1 to 10 carbon atoms, and “aryl” is preferably an aryl group having 6 to 20 carbon atoms.
The liquid crystal polyester which is particularly preferable from the standpoint of balance between heat-resistance, mechanical property and processability is a liquid crystal polyester resin containing a repeating structure unit represented by (A
1
) in an amount of at least 30 mol. %. Specifically, those having repeating structure units as shown in the following (a) to (f) are preferable:
(a) a combination of repeating unit (A
1
), together with repeating unit (B
1
) either alone or together with repeating unit (B
2
), and also with repeating unit (C
1
)
(b) a combination of repeating units (A
1
) and (A
2
)
(c) a combination of repeating units (A
1
) and (A
2
), together with repeating unit (B
1
) either alone or together with repeating unit (B
2
), and also with. repeating unit (C
1
)
(d) a combination of. repeating unit (A
1
), together with repeating units (B
1
) and (B
3
) either alone or together with repeating unit (B
2
), and also with repeating unit (C
1
)
(e) a combination of repeating unit (A
1
), together with repeating unit (B
1
) either alone or together with repeating unit (B
2
), and also with repeating units (C
1
) and (C
3
)
(f) a combination of repeating units (A
1
) and (A
2
), together with repeating units (B
1
) and (C
2
).
Known methods can be adopted for preparing liquid crystal polyester resins used in the present invention. For example, liquid crystal polyester resins of (a) and (b) are described in Japanese Patent Kokoku Publication (JP-B) Nos. 47-47870, 63-3888, and the like.
The carbon fiber used in the present invention is a fibrous substance wherein usually 90% or more of the chemical composition is composed of carbon fiber, and polyacrylonitrile, pitch, regenerated cellulose and the like can be used as the raw material thereof. Those obtained by carbonization treatment at 1000 to 2000° C. of a fibrous precursor which is obtained by spinning using these raw materials, or those obtained by graphitization treatment at 2000 to 3000° C. are usually used. As the carbon fiber, those of which surface has been activated by a method such as anodic oxidation and the like can be used.
The surface treatment of carbon fiber with an urethane resin means coating treatment of a part or all of the surface of carbon fiber with an un-cured or cured urethane resin, as well as sizing treatment of carbon fiber. The surface treatment contributes to handling property of carbon fiber, affinity with a liquid crystal polyester resin, and the like.
For the surface treatment of carbon fiber with an urethane resin, there is usually a procedure in which an urethane resin is made into an emulsion with an anionic, cationic or nonionic surfactant, a carbon fiber bundle is immersed into the emulsion, and moisture is removed by drying. If necessary, the urethane resin may sometimes be cured by heating.
As the un-cured urethane resin, an isocyanate can be used singly or a mixed solution of an isocyanate and a polyol can be used. If necessary, a catalyst such as an amine and the like may also be contained. Further, a part of the un-cured urethane resin may also be cured. Examples of the isocyanate include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI) and the like, and examples of the polyol include various polyether polyols, polyester polyols and the like.
In the present invention, the amount of an urethane resin in carbon fiber which has been surface-treatment with an urethane resin is from 0.5 to 5.0% by weight, preferably from 1.0 to 3.0% by weight. The amount of an urethane resin can be measured by reduction in weight in solution-removing or decomposition-removing an urethane resin from carbon fiber which has been surface-treated with an urethane resin. When the amount of an urethane resin is less than 0.5% by weight, the surface treatment of carbon fiber is insufficient, handling property is poor, and compounding into a liquid crystal polyester resin becomes difficult, undesirably. On the other hand, when the amount of an urethane resin is over
Maeda Mituo
Nakamura Hiroshi
Sumitomo Chemical Company Limited
Wu Shean C.
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