Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2002-11-29
2004-09-14
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S342000, C524S261000, C430S270100
Reexamination Certificate
active
06790914
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a resin film formed by using a composition comprising a cyclic olefin addition copolymer having an alkoxysilyl group and, optionally, an organosilane compound and/or a metal oxide.
The present invention also relates to a crosslinked resin film in which the cyclic olefin addition copolymer is crosslinked through siloxane bonds, and to a process for producing the crosslinked resin film.
The present invention further relates to a liquid crystal substrate film, a polarizing film, a surface protective film, a retardation film, a transparent conductive film, and a light diffusion film used for a liquid crystal display device and an electroluminescent (EL) display device which are obtained by using the (crosslinked) resin film which is excellent in optical transparency, heat resistance, hygroscopic resistance, liquid crystal resistance, dimensional stability, adhesion, and the like.
2. Description of Background Art
A liquid crystal display device and an EL display device excel in image quality, are thin and lightweight, and consume only a small amount of electric power. Therefore, these display devices are widely used for calculators, watches, portable telephones, personal computers, televisions, projectors, ATMs, display devices for vehicles such as car navigation systems, and the like. The liquid crystal display device and EL display device consist of various parts and materials. As examples of parts and materials for the liquid crystal display device, a liquid crystal, liquid crystal alignment film, liquid crystal substrate, transparent electrode, color filter, polarizing film, light guiding plate, transparent conductive film, retardation film, surface protective film, light diffusion film, prism sheet, spacer, sealant, and the like can be given. The liquid crystal display device is manufactured by assembling these parts and materials and installing module parts such as a driver IC, printed board, and backlight. As examples of parts and materials for the EL display device, an electroluminescent (EL) element, polarizing film, retardation film, transparent electrode, and the like can be given. The EL display device are manufactured by assembling these parts and materials.
Conventionally, a glass substrate has been mainly used as the liquid crystal substrate. However, since glass has low mechanical strength, it is difficult to decrease the thickness of the display device. Moreover, since the glass substrate lacks flexibility, the degree of freedom relating to the shape of the substrate is limited. Furthermore, occurrence of cracks in the glass substrate results in a decrease in productivity. In recent years, portable equipment such as portable information terminals including portable telephones, notebook type personal computers, and sub-notebook type personal computers has been widely used. A liquid crystal display device and a liquid crystal substrate used for this type of equipment must be lightweight and thin, and must not crack. Therefore, a liquid crystal substrate film formed of a transparent resin is used for a liquid crystal display device for which these properties are important instead of a glass substrate. In the case of using a glass substrate, an alignment film applied to the substrate is sintered at a high temperature of 200° C. or more. However, heat resistance of a liquid crystal substrate film made of polyethersulfone (PES), which is a transparent resin and widely used in this application, is as low as 160 to 170° C. Therefore, a transparent resin film having higher heat resistance has been demanded.
A polarizing film divides incident light into two polarized components which intersect each other. The polarizing film allows one of the two polarized components to pass through, and absorbs or disperses the other component. As the polarizing film, a polyvinyl alcohol film in which the molecules are oriented in a uniform direction and a dichromatic substance such as iodine or a pigment is absorbed thereon has been used, for example. However, such a polarizing film has insufficient mechanical strength in the direction of the transmission axis, and shrinks due to heat or moisture. Therefore, surface protective films are provided on each side of the polarizing film as protective layers.
The surface protective film must have low birefringence, high heat resistance, low hygroscopicity, high mechanical strength, excellent surface smoothness, high resolution, excellent adhesion to a tackifier, and the like. Conventionally, a triacetyl cellulose (TAC) film, which is produced by using a casting method and has low birefringence and excellent surface smoothness, has been used as the surface protective film. However, durability, heat resistance, mechanical strength, birefringence, and adhesion to a tackifier of the TAC film is insufficient at a high temperature and high humidity. Therefore, a material having higher heat resistance and the like has been demanded.
A retardation film is used in an STN (super-twisted nematic) liquid crystal display device to compensate for wavelength dependent coloration of the refractive index occurring when twisting liquid crystal molecules. The retardation film must have uniform birefringence over the entire surface and show no change in optical characteristics, even under severe conditions at a high temperature and high humidity, in order to obtain a vivid color and a high-resolution image. In the liquid crystal display device, the retardation film is layered on the polarizing film through an adhesive layer. As the retardation film, a film obtained by stretching and orienting a polycarbonate (PC) film is generally used. However, since the PC film has a large photoelastic coefficient of 9×10
−12
cm
2
/dyn, birefringence of the PC film is excessively increased, becomes nonuniform, or is changed due to only a small amount of stress applied when assembling or due to environmental changes. Moreover, the PC film causes problems when forming the film or assembling the device due to low surface hardness. Therefore, a material capable of replacing the PC film has been demanded.
A transparent conductive film has a structure in which a transparent conductive film is layered on a transparent film substrate. The transparent film substrate must excel in heat resistance, surface smoothness, optical characteristics, and moisture resistance. Conventionally, polyethersulfone (PES) or polyarylate (PAR) has been used as the transparent film substrate. However, the PES film has inferior transparency and the PAR film tends to cause optical distortion to occur. Therefore, a complicated technique is necessary for obtaining a transparent and optically uniform film.
A light diffusion film is layered on the backlight of the liquid crystal display in order to diffuse light or improve brightness. The light diffusion film is generally formed by forming a fine pattern on the surface of a transparent sheet or film by means of embossing or applying a photocurable resin. As the substrate for the light diffusion film, PC or polyethyleneterephthalate (PET) is generally used. However, since the PC film may be easily damaged due to low surface hardness, transparency of the film may be impaired in the case where the film is damaged when forming a fine pattern or assembling the display device. Moreover, since the PET film has insufficient transparency, a liquid crystal display device manufactured by using the PET film lacks brightness, whereby image quality may be impaired. Moreover, since the PET film has insufficient heat resistance, it is difficult to form a uniform fine pattern due to occurrence of warping of the film.
A prism sheet is used to improve brightness of the liquid crystal display device by collecting light diffused through the light diffusion film at the an angle of view of the liquid crystal display device. The prism sheet is used for a large-sized color STN display and color TFT display. As the substrate for the prism sheet, a PC film is generally used. However, further i
Hashiguchi Yuuichi
Kanamori Tarou
Kawahara Kouji
Maruyama Yooichiroh
Oshima Noboru
Hu Henry S.
Wu David W.
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