Compositions – Liquid crystal compositions – Containing nonsteryl liquid crystalline compound of...
Reexamination Certificate
2002-02-22
2003-12-02
Huff, Mark F. (Department: 1756)
Compositions
Liquid crystal compositions
Containing nonsteryl liquid crystalline compound of...
C252S299640, C252S299650, C252S299660, C252S299670
Reexamination Certificate
active
06656386
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a wholly aromatic liquid crystalline polyester resin composition which exhibits a good combination of improved melt flowing property and high heat resistance.
2. Related Arts
Liquid crystalline polyester resins (hereafter referred to as LCP(s)) have inflexible molecular structure and exhibit anisotropic melt phases. Upon molding, the inflexible moleculars highly orient to give molded products with excellent mechanical properties as well as high heat resistance. Due to these outstanding properties, LCPs are used as super engineering plastics and have attracted the attention of the art.
LCPs were first brought to the market in 1980s and the LCP market has expanded since then because of their excellent mechanical properties, soldering heat-resistance, excellent molding properties and the other properties. LCPs are especially admired in the field of electronic and electric devices wherein light, thin and small parts are preferred since they exhibit good melt flowability and cause less flash formation upon molding,
Along with the recent rapid advances in information technology, even smaller and thinner devices are desired in the electric and electronic fields, and therefore LCPs with improved heat-resistance as well as improved melt flowability are desired.
In order to be resistant to the reflow-soldering temperature, the melting peak of LCP, which is determined with differential scanning calorimetry (DSC) should be more than 310° C. However, setting speed of such heat-resistant LCP as above is generally high and the flowability of the fused resin is low. In order to improve the flowability of a fused LCP, Japanese Patent Application Laid Open No. 03-252457 discloses a resin composition obtained by compounding a small amount of p-hydroxybenzoic acid (PHB) oligomer into the LCP; Japanese Patent No. 2823873 discloses a resin composition with lower melt viscosity obtained by compounding a LCP having low molecular weight into a conventional LCP. Although the above prior art compositions achieved some improved melt flowability, there are several practical problems such as decreased heat-resistance and mechanical strength of the molded articles obtained from the composition.
It was also proposed to compound other resins into a conventional LCP to improve its melt flowability. However, compatibility of the LCP with the other resin is generally poor and therefore, mechanical strength of the resulting molded article is significantly affected. If the other resin is blended into the LCP, the resulting composition offers a molded article with only a reduced heat resistance and therefore, cannot be processed with reflow-soldering procedure. Further more, proposed methods for improving melt flowability of a LCP by means of controlling its melt viscosity, admixing fine fillers or the like could not give practically useful compositions.
Further more, Japanese Patent No. 2611376 disclose a resin composition with improved flowing property obtained by blending two LCPs having different heat deflection temperatures, and U.S. Pat. No. 5,976,406 disclosed a resin composition with improved flowability obtained by blending two LCPs having different flow temperatures. However, mechanical properties or heat resistance of the molded articles obtained by using said LCPs were not enough.
SUMMARY OF THE INVENTION
The object of the present invention is to improve melt flowability of a liquid crystalline polyester resin while keeping the conventional mechanical properties and heat resistance of the molded article made from the same so that the article can be subjected to the reflow-soldering process.
The present inventors studied to improve melt flowability of heat-resistant liquid crystalline polyester resin of which melting peak is equal to or higher than 310° C., and have surprisingly found that by compounding a specific amount of a liquid crystalline polyester resin of which melting peak is not greater than 300° C. into the original resin, an improved melt flowability was attained.
Accordingly, the present invention provides a wholly aromatic liquid crystalline resin composition comprising
97-60 parts by weight of a wholly aromatic liquid crystalline polyester resin (A) having melting peak determined by differential scanning calorimetry (DSC) equal to or higher than 310° C.; and
3-40 parts by weight of a wholly aromatic liquid crystalline polyester resin (B) having melting peak determined by differential scanning calorimetry (DSC) equal to or lower than 300° C.
Said composition exhibits an improved melt flowability than that of the liquid crystalline polyester resin (A) alone.
The present invention also provides a method to improve melt flowability of a wholly aromatic liquid crystalline polyester resin (A) having melting peak determined by differential scanning calorimetry equal to or higher than 310° C., comprising the step of compounding 3-40 parts by weight of a wholly aromatic liquid crystalline polyester resin (B) having melting peak determined by differential scanning calorimetry equal to or lower than 300° C. into 97-60 parts by weight of the liquid crystalline polyester resin (A).
The present invention further provides a molded article prepared by using the wholly aromatic liquid crystalline polyester resin composition of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The melting peak of a liquid crystalline polyester resin or liquid crystalline polyester resin composition used herein is determined by means of differential scanning calorimetry (DSC). The detailed method for determination is as follows:
The differential scanning calorimeter DSC-6200 (Seiko Instruments Inc., Chiba, Japan) or a same type of DSC device may be used. The measurement may be carried out at the sensitivity of 1.6 &mgr;W. The LCPs to be examined are pulverized into fine particles and 20 mg of the powder are weighted. The powder is heated under stream of nitrogen gas from 50° C. to 375° C. at the rate of 20° C./minute, kept at 375° C. for 10 minutes (Step 1). Then the composition is cooled to 50° C. at the rate of 20° C./minute (Step 2) and then, heated again to 395° C. at the same rate (Step 3). Endothermic peak found in the third step is recorded as melting peak.
Examples of the monomers used for preparing LCPs (A) or (B) used herein may include aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, aromatic bivalent phenols, aromatic diamines, aromatic hydroxy amines, and aromatic aminocarboxylic acids.
Examples of aromatic hydroxycarboxylic acids include p-hydroxy benzoic acid, 2-hydroxy-3-naphthoic acid, 2-hydroxy-6-naphthoic acid, 2-hydroxy-7-naphthoic acid, 3-methyl-4-hydroxybenzoic acid, 3,5-dimethyl-4-hydroxy benzoic acid, 2,6-dimethyl-4-hydroxybenzoic acid, 2-hydroxy-5-methyl-6-naphthoic acid, 2-hydroxy-5,7-dimethyl-6-naphthoic acid, 3-chloro-4-hydroxybenzoic acid, 2-chloro-4-hydroxybenzoic acid, 2,3-dichloro-4-hydroxybenzoic acid, 3-bromo-4-hydroxybenzoic acid, 2-hydroxy-5-chloro-6-naphthoic acid, 2-hydroxy-7-chloro-6-naphthoic acid, 2-hydroxy-5,7-dichloro-6-naphthoic acid and 4-hydroxy-4′-biphenylcarboxylic acid, and alkyl, alkoxy and halogen substituted derivatives thereof as well as ester forming derivatives thereof. Among the above, p-hydroxy benzoic acid and 2-hydroxy-6-naphthoic acid are preferable.
Examples of aromatic dicarboxylic acids include terephthalic acid, chloroterephthalic acid, dichloro terephthalic acid, bromoterephthalic acid, methylterephthalic acid, dimethylterephthalic acid, ethylterephthalic acid, methoxyterephthalic acid, ethoxyterephthalic acid, isophthalic acid, 4,4′-biphenyldicarboxylic acid, 3,4′-biphenyldicarboxylic acid, 4,4″-terphenyidicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 2,7-naphthalene-dicarboxylic acid, 1,6-naphthalene-dicarboxylic acid, diphenylether-4,4′-dicarboxylic acid and alkyl, alkoxy and halogen substituted derivatives thereof as well as ester forming derivatives thereof. Among the above, terephthalic acid, 2,6-naphthalene
Egawa Masaru
Owaki Takamasa
Suenaga Jun-ichi
Huff Mark F.
Kabushiki Kaisha Ueno Seiyaku Oyo Kenkujo
Sadula Jennifer R.
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