Stock material or miscellaneous articles – Liquid crystal optical display having layer of specified... – With substrate layer of specified composition
Reexamination Certificate
2001-06-01
2003-08-12
Lam, Cathy (Department: 1775)
Stock material or miscellaneous articles
Liquid crystal optical display having layer of specified...
With substrate layer of specified composition
C428S209000, C428S901000, C174S258000, C264S466000, C264S467000
Reexamination Certificate
active
06605324
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a liquid-crystalline resin laminated film having the advantages of good surface smoothness, good adhesiveness and low anisotropy in characteristics, to a method for producing it, and to a circuit board of the liquid-crystalline resin laminated film.
BACKGROUND ART
Liquid-crystalline resin has high strength and good heat resistance; its linear expansion coefficient is low; its insulating properties and gas-barrier properties are good; and its moisture absorption is low. Various injection moldings and fibers of the resin have heretofore been put to practical use. Printed wiring boards of the resin for IC are being developed.
While in melt, molecules of liquid-crystalline resin are oriented as they flow. Therefore, when the resin is extruded in an ordinary manner, it is greatly oriented in the flow direction and gives films of strong anisotropy. In addition, it does not uniformly flow in the transverse direction while extruded, and its films therefore have continuous streaks of uneven flow in the machine direction and their thickness variation is significant.
To solve the problem of anisotropy of the resin films in the flow direction, inflation methods are proposed in Japanese Patent Publication No. 39533/1994 and Japanese Patent Laid-Open No. 286626/1992. The liquid-crystalline resin films obtained according to the methods may be basically free from the problem of unbalanced physical properties in the MD/TD directions, but are still problematic in point of their surface roughness intrinsic to liquid-crystalline resin (including poor surface smoothness, poor abrasion resistance, and thickness variation). On the other hand, Japanese Patent Laid-Open Nos. 251438/1995 and 323506/1995 propose a method of laminating a liquid-crystalline resin and a heat-resistant resin through flat die extrusion, followed by biaxially stretching the resulting laminated film; and Japanese Patent Laid-Open No. 76397/1997 proposes a method of laminating a thermoplastic resin film of good adhesiveness on the surface of a liquid-crystalline resin film. The liquid-crystalline resin films obtained according to these methods could solve the problem of unbalanced physical properties in the MD/TD directions. However, in them, the interlayer adhesiveness between the liquid-crystalline resin layer and the non-liquid-crystalline resin layer is small, not enough to prevent interlayer peeling between them, and the quality of the films is still poor.
As so mentioned above, films produced through inflation are not good since their thickness is not even and, in addition, their surface smoothness and abrasion resistance are poor and they do not solve the problem intrinsic to liquid-crystalline resin. On the other hand, when a liquid-crystalline resin and a heat-resistant resin are laminated through flat die extrusion and the resulting laminated film is biaxially stretched, the anisotropy of the liquid-crystalline resin layer and the adhesiveness insufficiency of the film surface could be solved, but interlayer peeling between the liquid-crystalline resin layer and the heat-resistant resin layer is still inevitable and the film quality is therefore poor.
In addition, liquid-crystal line resin is poorly adhesive to other materials, and therefore requires chemical treatment and plasma treatment.
DISCLOSURE OF THE INVENTION
The present invention is to solve the problems in the related art mentioned above, and to provide a liquid-crystalline resin laminated film having the advantages of good interlayer adhesiveness of its liquid-crystalline resin layer to heat-resistant resin laminated thereon, good surface smoothness, good surface adhesiveness, and low anisotropy in characteristics, a method for producing it, and a circuit board of the liquid-crystalline resin laminated film.
The liquid-crystalline resin laminated film of the invention that attains the object is (a) a film comprising a liquid-crystalline resin layer and a non-liquid-crystalline thermoplastic resin layer laminated on at least one surface of the liquid-crystalline resin layer, which is characterized in that its interlayer adhesiveness is at least 30 N/cm; or (b) a film comprising a liquid-crystalline resin layer and a non-liquid-crystalline thermoplastic resin layer laminated on at least one surface of the liquid-crystalline resin layer, which is characterized in that it satisfies T
N
≧T
L
wherein T
N
and T
L
indicate the thermal deformation temperature of the non-liquid-crystalline thermoplastic resin layer and that of the liquid-crystalline resin layer, respectively, measured through thermal mechanical analysis (TMA).
The method for producing the liquid-crystalline resin laminated film of the invention that attains the object is characterized in that it comprises forming a non-liquid-crystalline thermoplastic resin layer on at least one surface of a liquid-crystalline resin layer through co-extrusion, followed by stretching the resulting laminated film.
The circuit board of the liquid-crystalline resin laminated film of the invention that attains the object is characterized in that it comprises a conductor pattern formed on at least one surface of the liquid-crystalline resin laminated film.
BEST MODES OF CARRYING OUT THE INVENTION
In the invention, the liquid-crystalline resin is a resin having a crystalline regular structure even in melt, including, for example, thermotropic liquid-crystal resins, and it may be any and every known one.
For example, for liquid-crystalline polyester resins, preferred is a liquid-crystalline polyester comprising from 40 to 90% by weight of an essential mesogen, parahydroxybenzoic acid (HBA) component and containing 4,4′-dihydroxybiphenyl (DHB) for improving the fluidity of the polyester. In this, the mesogen may be bonded to the polymer chain in any mode of random copolymerization, block copolymerization, branch copolymerization, or their combination of composite copolymerization. In the invention, preferred are liquid-crystalline resins comprising polyethylene terephthalate (PET) or polyethylene naphthalate (PEN)/HBA/DHB/terephthalic acid (TPA), etc.; copolymers comprising, as the essential ingredient, HBA/6-hydroxy-2-naphthoic acid; copolymers of HBA/4,4′-dihydroxybiphenyl with terephthalic acid and/or isophthalic acid; copolymers of 6-hydroxy-2-naphthoic acid with para-aminophenol; and copolymers of HBA/hydroquinone (HQ)/sebacic acid (SA). The liquid-crystalline polyester resins comprising the components as above have a regular structure even in melt, and their molecules are readily oriented in the flow direction, as flowing in melt.
In place of using the liquid-crystalline resin alone, also usable are polymer alloys containing any of the above-mentioned liquid-crystalline resins. For the alloying polymer to be mixed with or chemically bonded to the liquid-crystalline resins, usable are thermoplastic resins such as polyesters, polyamides, polyimides, polyamidimides, polyether-imides, polyarylates, polyphenylene sulfides, polyether-ether ketones, polyether sulfones, polysulfones, etc. However, these are not limitative. The blend ratio of the liquid-crystalline resin and the alloying polymer preferably falls between 10:90 and 90:10, more preferably between 20:80 and 80:20 by weight. Polymer alloys containing liquid-crystalline resin have good properties intrinsic to the liquid-crystalline resin therein.
For the laminated film of the invention, the non-liquid-crystalline thermoplastic resins to satisfy T
N
≧T
L
, in which T
N
and T
L
indicate the thermal deformation temperature of the non-liquid-crystalline thermoplastic resin layer and that of the liquid-crystalline resin layer, respectively, measured through thermal mechanical analysis (TMA), are preferably polyamides, polyimides, polyamidimides, polyether-imides, polyarylates, polyphenylene sulfides, polyether-etherketones, polyether sulfones, polysulfones, and their copolymers and blends. The non-liquid-crystalline thermoplastic resins to satisfy T
N1
≧T
L1
after heat treatment of the laminated
Machida Tetsuya
Sakamoto Jun
Tsunashima Kenji
Lam Cathy
Piper Rudnick LLP
Toray Industries Inc.
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