Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-12-14
2002-12-17
Yoon, Tae H. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S494000, C524S603000, C524S604000, C252S299010
Reexamination Certificate
active
06495616
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal polyester resin composition and a molded product thereof. More precisely, it relates to a liquid crystal polyester resin composition containing hollow sphere and a molded product thereof.
2. Description of the Related Art
Because of their excellent thermal resistance and mechanical physical properties as well as their excellent flowability in molten state, i.e. processability, melt liquid crystallinity polyester reins that exhibit liquid crystallinity in molten state (hereinafter, such resin is referred to as liquid crystal polyester resin) have been used in various field including electric and electronic fields as molding materials which can be subjected to precise molding. In recent years, in the electric and electronic fields, downsizing, lightening and performance-elevating are more and more required. Following this, more light-weighted resins have been required for liquid crystal polyester resins as the materials having necessary heat resistance, mechanical physical properties and processability.
As means for lightening liquid crystal polyester resins, a method of compounding hollow sphere has been known. For example, JP-A-58-93759 (JP-B-64-7626) and JP-A-64-74258 describe light-weighted and excellently isotropic resin compositions as well as molding products thereof.
In the conventional resin compositions containing hollow sphere and molded products, however, insufficient reproducibility was inevitable in production thereof, including instability in performance occurred by ununiformity in degree of fracture of hollow spheres, and thus they were not satisfactory for production in the industrial scale.
SUMMARY OF THE INVENTION
An object of the invention is to provide, with good reproducibility, a liquid crystal polyester resin composition, which gives a molded product having necessary mechanical physical properties, light-weighted and excellently low thermal conductivity, and to provide a molded product thereof.
As the result of intensive studies, the present inventors have found that the above object can be attained by a specific liquid crystal polyester resin composition containing a specific amount of specific hollow spheres, and thus completed the present invention.
Accordingly, the present invention relates to (1) a liquid crystal polyester resin composition comprising 100 parts by weight of a liquid crystal polyester resin, 2 to 50 parts by weight of hollow sphere having an average particle diameter of 5 to 500 &mgr;m and a volume hollowness of 60 to 80%, and 0 to 40 parts by weight of inorganic fiber, wherein said liquid crystal polyester resin composition having an X value, defined below, of 10 to 50:
X=100×[(100/&rgr;
0
+&agr;/&rgr;
1
+&bgr;/&rgr;
3
)−(100+&agr;+&bgr;)/&rgr;]/(&agr;/&rgr;
1
−&agr;/&rgr;
2
)
in the formula, a represents the amount of the hollow sphere (part by weight based on 100 parts by weight of the liquid crystal polyester resin), &bgr; represents the amount of the inorganic fiber (part by weight based on 100 parts by weight of the liquid crystal polyester resin), &rgr;
0
represents the specific gravity of the liquid crystal polyester resin, &rgr;
1
represents the true specific gravity of the hollow sphere, &rgr;
2
represents the material specific gravity of the hollow sphere, &rgr;
3
represents the specific gravity of the inorganic fiber and &rgr; represents the specific gravity of ASTM No. 4 dumbbell (having a thickness of 2.5 mm) obtained by injection molding of said liquid crystal polyester resin composition.
Said liquid crystal polyester resin composition can be obtained by compounding 2 to 50 parts by weight of hollow sphere having an average particle diameter of 5 to 500 &mgr;m and a volume hollowness of 60 to 80%, and 0 to 40 parts by weight of inorganic fiber with 100 parts by weight of a liquid crystal polyester resin.
The present invention also relates to (2) a molded product obtained by molding the liquid crystal polyester resin composition according to the above described (1).
The present invention further relates to a molded product obtainable by molding a liquid crystal polyester resin compound comprising 100 parts by weight of a liquid crystal polyester resin, 2 to 50 parts by weight of hollow sphere having an average particle diameter of 5 to 500 &mgr;m and a volume hollowness of 60 to 80%, and 0 to 40 parts by weight of inorganic fiber, wherein said molded product having an X′ value, defined below, of 10 to 50:
X′=100×[(100/&rgr;
0
+&agr;/&rgr;
1
+&bgr;/&rgr;
3
)−(100+&agr;+&bgr;)/&rgr;]/(&agr;/&rgr;
1
−&agr;/&rgr;
2
)
in the formula, a represents the amount of the hollow sphere (part by weight based on 100 parts by weight of the liquid crystal polyester resin), &bgr; represents the amount of the inorganic fiber (part by weight based on 100 parts by weight of the liquid crystal polyester resin), &rgr;
0
represents the specific gravity of the liquid crystal polyester resin, &rgr;
1
represents the true specific gravity of the hollow sphere, &rgr;
2
represents the material specific gravity of the hollow sphere, &rgr;
3
represents the specific gravity of the inorganic fiber and &rgr;′ represents the specific gravity of said molded product.
DETAILED DESCRIPTION OF THE INVENTION
The liquid crystal polyester resin used in the invention is a polyester generally called thermotropic liquid crystal polymer, and forms an isotropic melt at a temperature of 400° C. or below. Examples include:
a resin comprising a combination of an aromatic dicarboxylic acid, an aromatic diol and an aromatic hydroxycarboxylic acid;
a resin comprising different aromatic hydroxycarboxylic acids;
a resin comprising a combination of an aromatic dicarboxylic acid and an aromatic diol;
a resin formed by reacting a polyester such as polyethylene terephthalate or the like with an aromatic hydroxycarboxylic acid; and the like. As materials for synthesis, sometimes ester-forming derivatives thereof are used in place of these aromatic dicarboxylic acid, aromatic diol and aromatic hydroxycarboxylic acid.
The structural unit of the liquid crystal polyester used in the present invention include the followings.
Structural units derived from aromatic hydroxycarboxylic acids:
Structural units derived from aromatic dicarboxylic acids:
Structural units derived from aromatic diols:
The liquid crystal polyester which is preferable from the standpoint of balance between heat-resistance, mechanical property and processability is a liquid crystal polyester resin containing the structural unit represented by (A
1
) in an amount of at least 30 mol %. Specifically, those structural units having following combinations are preferable.
Combination of (A
1
), (B
1
), (B
2
), and (C
1
).
Combination of (A
1
), (B
1
), (B
2
), and (C
2
).
Combination of (A
1
), (B
1
), (B
2
), (C
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 hollow sphere used in the invention is generally called balloon. Examples of materials for the hollow sphere include inorganic materials such as alumina, silica, glass and the like; and organic materials such as urea resins, phenol resins and the like. A mixture of two or more thereof may be used as required. Amongst them, glass is suitable from the viewpoint of thermal resistance and strength. Therefore, glass balloon is preferably used as the hollow sphere.
The average particle diameter of the hollow sphere used in the invention is 5 &mgr;m or more, preferably 10 &mgr;m or more, from the viewpoint of molding characteristics and mechanical strength. The average particle diameter is 500 &mgr;m or less, preferably 200 &mgr;m or less, from the viewpoint of fracture inhibition and molding characterist
Birch & Stewart Kolasch & Birch, LLP
Sumitomo Chemical Company Limited
Yoon Tae H.
LandOfFree
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