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
2002-04-30
2004-01-13
Nutter, Nathan M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S216000, C525S222000, C525S241000
Reexamination Certificate
active
06677404
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a light-diffusing resin composition excellent in both light transmission property and light diffusion property and moreover in light resistance. The present invention also relates to light-diffusing molded or formed products obtained by molding or forming the light-diffusing resin composition into various molded or formed products such as sheets (plates).
BACKGROUND ART
Light-diffusing molded or formed products of a synthetic resin having light diffusion property are used in application fields of, for example, illumination covers, light-diffusing members (light-diffusing plates) for light sources in internally illuminating type displays and liquid crystal displays, etc. The light-diffusing molded or formed products-are molded or formed products which can cause incident light to diffuse and go out, and are used in the case where uniform illumination is difficult due to the kind of a light source or a positional relation.
A light-diffusing molded or formed product is generally required to have a high light transmittance and high light diffusion property in combination. For example, in a back light type liquid crystal display, a back light is arranged at the rear of a liquid crystal display panel. As the back light, a vertical type or an edge type is representative. The vertical type back light has a structure that one or plural light sources are arranged just under the liquid crystal display panel, and a light-diffusing plate is arranged over the light source. The edge type back light has a structure that a linear light source is arranged at a side part of a liquid crystal display panel, and a reflector and a light-diffusing plate are arranged in combination. In the back light of any type, it is required that the liquid crystal display panel can be illuminated as uniform diffused light free of any mottle by the outgoing light from the light source so as to prevent the liquid crystal display panel from causing mottle of light and shade. The back light is also required to have uniform and high luminance.
In order for the back light to satisfy such requirements, it is important to improve the light transmittance and light diffusion property of the light-diffusing plate. Further, the light-diffusing plate is required to have excellent light resistance to prevent its performance from being deteriorated due to discoloration or the like even by the outgoing light from the light source over a long period of time.
As described above, the light-diffusing molded or formed products are required to permit uniformly diffusing the outgoing light from the light source almost without causing luminance mottle, mottle of light and shade, periodical mottle of light and shade, and/or the like, have excellent uniformity of luminance, permit the outgoing of the diffused light at high luminance and have excellent light resistance.
More specifically, the light-diffusing molded or formed products must have a high proportion of the outgoing light from the plane of outgoing to the incident light from the plane of incidence, i.e., a high total light transmittance with a parallel ray transmittance combined with a diffused ray transmittance in order to effectively utilize the light from the light source. Therefore, the light-diffusing molded or formed products are required to be hard to reflect and absorb the light on the plane of incidence. From the purpose of diffusing light, the light-diffusing molded or formed products cannot sufficiently fulfill their functions unless the diffused ray transmittance is high.
As the light-diffusing molded or formed products, there have heretofore been proposed, for example, a light-diffusing sheet formed of a transparent resin film containing closed cells having an average particle diameter of 1 to 30 &mgr;m (Japanese Patent Application Laid-Open No. 5-281403) and a light-diffusing molded or formed methacrylic resin to which particles of a crosslinkable polymer and fine silicone particles are added (Japanese Patent Application Laid-Open No. 6-107881).
In these light-diffusing molded or formed products, however, the light transmission property is lowered when the number of the closed cells or fine particles dispersed is increased though the light diffusion property is improved. When the number of the closed cells or fine particles is decreased on the other hand, the light diffusion property is lowered though the light transmission property is improved. As described above, there is an adverse correlation between the light transmission property and the light diffusion property. Therefore, either light transmission property or light diffusion property may become insufficient according to the use. Thus, a light-diffusing molded or formed product high in both light transmission property and light diffusion property is sought in application fields of light-diffusing plates and the like.
In order to solve the above-described problem, Japanese Patent Application Laid-Open No. 8-327806 has proposed a light-diffusing resin composition obtained by dispersing transparent fine polymer particles in a thermoplastic norbornene resin matrix, and a light-diffusing molded or formed product obtained by molding or forming the light-diffusing resin composition. The light-diffusing molded or formed product has become insufficient in light resistance, dimensional stability or the like due to selection or variation of molding or forming conditions in some cases though it is excellent in both light transmission property and light diffusion property.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a light-diffusing resin composition excellent in both light transmission property and light diffusion property and moreover in light resistance.
Another object of the present invention is to provide a light-diffusing molded or formed product excellent in both light transmission property and light diffusion property and moreover in light resistance by using such a light-diffusing resin composition.
The present inventors have carried out an extensive investigation with a view toward achieving the above objects. As a result, the present inventors have conceived a light-diffusing resin composition comprising a specific alicyclic structure-containing resin and transparent fine polymer particles. It has been found that a light-diffusing molded or formed product obtained by molding or forming this light-diffusing resin composition is high in total light transmittance and in diffused ray transmittance (turbidity) at the same time, and moreover excellent in light resistance and hence extremely little in change of chromaticity even upon exposure to light over a long period of time. The present invention has been led to completion on the basis of these findings.
According to the present invention, there is thus provided a light-diffusing resin composition comprising at least one alicyclic structure-containing resin (A) selected from the group consisting of (co)polymers (A1) having repeating units derived from an alicyclic structure-containing ethylenically unsaturated monomer and (co)polymers (A2) having repeating units which are derived from an aromatic vinyl monomer and in which-the aromatic rings have been converted to alicyclic structures through hydrogenation after polymerization and transparent fine polymer particles (B).
According to the present invention, there is also provided a light-diffusing molded or formed resin obtained by molding or forming the light-diffusing resin composition.
BEST MODE FOR CARRYING OUT THE INVENTION
The light-diffusing resin composition according to the present invention is a resin composition comprising a specific alicyclic structure-containing resin and transparent fine polymer particles, in which the transparent fine polymer particles are dispersed in a matrix composed of the alicyclic structure-containing resin.
The alicyclic structure-containing resin (A) useful in the practice of the present invention is at least one selected from the group consisting of (co)polymers (A1) having repeating units d
Nutter Nathan M.
Zeon Corporation
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