Compositions – Liquid crystal compositions
Reexamination Certificate
2001-06-01
2004-03-09
Huff, Mark F. (Department: 1756)
Compositions
Liquid crystal compositions
C525S152000
Reexamination Certificate
active
06702955
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a liquid crystal polymer composition containing a fibrous filler and a particulate filler, and more particularly, it relates to a connector molded from such a liquid crystal polymer composition and excellent in prevention of deformation caused by warpage.
2. Background Art
Liquid crystal polymers, which are capable of forming an anisotropic molten phase, have been known as good materials having a dimensional accuracy among the thermoplastic resins. However, in the fields of electric and electronic parts in recent years, requests are becoming more and more severe for high precision, labor saving and low cost. Moreover, there has been a demand for heat resistance of the resinous parts and for dimensional accuracy of molded products at high temperature for purposes of making the products lighter in weight and smaller in size. Particularly, in view of the properties such as heat resistance and fluidity, the liquid crystal polymer is used in connectors with many terminals wherein a ratio (L/t) of the length (L) of the product to the average thickness (t) thereof is at least 100 and ratio (L/h) of the length (L) of the product to the height (h) thereof is at least 10. That is, in the case of common connectors with L/t of less than 70, there is almost no problem of deformation caused by warpage even if the liquid crystal polymer just filled with glass fiber. On the other hand, in the case of ones having L/t of 70 or more, there is a tendency to sudden increase in deformation caused by warpage after a molding or after an IR reflow due to a difference in shrinkage upon molding near a gate and a fluid terminal and also to a difference in orientation between the direction of flow and the transverse direction to the flow caused by the property of the liquid crystal polymer. Further, even if L/t is 100 or more, when L/h of the product is 10 or less, deformation by warpage rarely occurs by a rib effect, while the deformation by warpage significantly occurs in a product with the L/h of 10 or more. Thus, there are some cases that the connector after molding or after IR reflow cannot be in industrial use due to a deformation by warpage.
Up to now, compounding of various fillers has been carried out as an attempt for improving the mechanical properties and surface properties. However, investigation in fillers with an object of improving deformation caused by warpage has not been conducted so much.
For example, the use of various kinds of fillers has been disclosed in JP-A 63-146958. In that invention, adding amount and type of the filler are regulated, but the object thereof is to improve the surface properties of the liquid crystal polyester resin compositions, and neither attention nor consideration has been made on the deformation caused by warpage. Although amount and type of the filler are changed in it, any of them is hardly believed to fully achieve the low deformation by warpage.
Accordingly, there has been a demand for a material, which is suitable for connectors wherein the ratio (L/t) of the length (L) of the product to the average thickness (t) thereof is at least 100 and the ratio (L/h) of the length (L) of the product to the height (h) thereof is at least 10, and has a good dimensional accuracy and further little deformation by warpage without a great deterioration in mechanical properties such as bending property.
SUMMARY OF THE INVENTION
In view of the above-mentioned problem, the present inventors have carried out an intensive investigation for a material having an excellent property concerning the deformation caused by warpage and have found that, when a liquid crystal polymer (A) and one or more filler(s) are blended in a specific compounding ratio, the said deformation can be reduced without too much deterioration of the mechanical properties, whereupon they have accomplished the present invention.
That is, the present invention is to provide a liquid crystal polymer composition for connectors having a ratio (L/t) of the length (L) of the product to the average thickness (t) thereof of at least 100 and a ratio (L/h) of the length (L) of the product to the height (h) thereof of at least 10, which is obtained by blending 100 parts by weight of a liquid crystal polymer (A) with 5 to 100 parts by weight of a fibrous filler (B) having an average fiber diameter of 0.5 to 20 &mgr;m and an average aspect ratio not exceeding 10, and 5 to 100 parts by weight of a particulate filler (C) having an average particle diameter of 0.1 to 50 &mgr;m, the total amount of the fillers not exceeding 150 parts by weight.
The present invention is a computer machine or industrial equipment, or other machines, containing the connector described above. The present invention is also use of the above-described composition for connectors.
The present invention is a process for producing a connector, which comprises blending 100 parts by weight of a liquid crystal polymer (A) with 5 to 100 parts by weight of a fibrous filler (B) having an average fiber diameter of 0.5 to 20 &mgr;m and an average aspect ratio not exceeding 10, and 5 to 100 parts by weight of a particulate filler (C) having an average particle diameter of 0.1 to 50 &mgr;m, the total amount of the fillers not exceeding 150 parts by weight, and molding the mixture into a connector having a ratio (L/t) of the length (L) of the product to the average thickness (t) thereof of at least 100 and a ratio (L/h) of the length (L) of the product to the height (h) thereof of at least 10, and a method of preventing from deformation caused by warpage, a connector, which comprises blending 100 parts by weight of a liquid crystal polymer (A) with 5 to 100 parts by weight of a fibrous filler (B) having an average fiber diameter of 0.5 to 20 &mgr;m and an average aspect ratio not exceeding 10, and 5 to 100 parts by weight of a particulate filler (C) having an average particle diameter of 0.1 to 50 &mgr;m, the total amount of the fillers not exceeding 150 parts by weight, and molding the mixture to have a ratio (L/t) of the length (L) of the product to the average thickness (t) thereof of at least 100 and a ratio (L/h) of the length (L) of the product to the height (h) thereof of at least 10.
In the present invention, for example, one kind of filler materials is added in the two forms of (B) and (C). Alternatively, two different kinds of filler materials may be each formed into the shapes (B) and (C), and added. The total amount of all the added fillers is preferably 10-150 parts by weight.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will now be illustrated in detail.
The liquid crystal polymer (A) used in the present invention is a melting-processable polymer having such a property that it can form an optically anisotropic molten phase.
The property of the anisotropic moltn phase can be confirmed by means of a common polarized test method utilizing orthogonal polarizers. To be more specific, confirmation of the anisotropic molten phase can be conducted by using a polarization microscope (manufactured by Leitz) and observing a melted sample placed on a Leitz hot stage in a nitrogen atmosphere with a magnification of 40. When tested between the orthogonal polarizers, the liquid crystal polymer which is applicable to the present invention is usually permeated through by the polarized light even under a stationary molten state and shows an optical anisotropy.
Although there is no particular limitation to the above-mentioned liquid crystal polymer (A), aromatic polyester or aromatic polyester amide is preferred. And the polyester partly containing the aromatic polyester or the aromatic polyester amide in the same molecular chain is also within the said range. Among these, substances having a logarithmic viscosity (I.V.) of preferably at least about 2.0 dl/g, more preferably, 2.0-10.0 dl/g upon dissolving in pentafluorophenol at 60° C. in a concentration of 0.1% by weight can be used.
With regard to the aromatic polyester or the aromatic polyester amide as a liquid cryst
Murakami Haruji
Ohtake Mineo
Huff Mark F.
Polyplastics Co. Ltd.
Sadula Jennifer R.
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