Stock material or miscellaneous articles – Structurally defined web or sheet – Including components having same physical characteristic in...
Reexamination Certificate
2001-08-22
2004-01-13
Chen, Vivian (Department: 1773)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including components having same physical characteristic in...
C428S216000, C428S339000, C428S480000, C428S483000, C428S323000, C428S325000, C428S327000, C428S328000, C428S329000, C428S330000, C428S331000, C428S910000, C359S483010, C359S487030, C359S488010, C359S494010, C359S506000, C359S580000, C359S582000, C359S584000, C359S586000, C359S589000
Reexamination Certificate
active
06677031
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a multilayer film and a refractive polarizer film and semi-transparent film in which the multilayer films are laminated. More specifically, it relates to the multilayer film in which a layer having low refractive index and a layer having high refractive index are laminated alternately and orderly and which selectively reflects light by structural interference between the layers, a refractive polarizer film and semi-transparent film in which the multilayer films are laminated.
BACKGROUND ART
When a multilayer film is prepared by laminating a layer having low refractive index and a layer having high refractive index alternately and repeatedly, it will be obtained an optical interference film which selectively reflects or transmits the light of specific wavelength by the structural optical interference between the layers. When the wavelength of the light which is selectively reflected or transmitted is within the range of visible light, such a multilayer film will be obtained as a film which has an excellent design imparted by structural color development, for example, a film which appears iridescent. Further, since the design obtained above is imparted not by dyes but by the structural color development of the multilayer film, there is no problem of fading. Further, since the multilayer film has high reflectance of light even if it does not use metal, it can also use the multilayer film as a metallic luster film or a reflective mirror. Furthermore, stretching the multilayer film can further control the refractive index of the surface direction between or in the layers. For example, if the refractive index of the surface direction in the layers has anisotropy, the multilayer film can also be used as a reflective polarizer film.
As a multilayer stretched film prepared by stretching such a multilayer film, WO95/17699 discloses a multilayered polymer film in which a crystalline naphthalenedicarboxylic acid polyester and another selected polymer whose refractive index associated with at least one in-plane axis is lower than that of the crystalline naphthalenedicarboxylic acid polyester are laminated alternately, wherein the film of multilayered polymer has a thickness of smaller than 0.5 &mgr;m and the refractive index associated with at least one in-plane axis of the crystalline naphthalenedicarboxylic acid polyester layer is higher than that of the adjacent layer comprising the above selected polymer.
Further, WO95/17303 discloses a reflective polarizer using the film of multilayered polymer which is indicated in the above WO95/17699.
However, since these films of multilayered polymer contain no slip agents in the surface layer in order to optically enhance light transmittance, they are difficult to handle, for example, to wind up. The difficulty in handling such as winding of the films will be not a serious problem when the films are thick. However, when the thin films are formed, they will be extremely difficult to wind and substantially impossible to handle.
Moreover, although the said two publications mention a copolymer and blend of polyethylene terephthalate or polynaphthalene terephthalate as the selected polymer in the description, only the copolymer is indicated in their examples, and it is not indicated at all about the blend therein. In addition, when the present inventors have attempted to use a multilayer laminated film comprising the copolymer which was disclosed in the examples of the aforementioned two publications as a semi-transparent film, it has been found that the multilayer laminated film was significantly inefficient for producing a variety of products since copolymers of different refractive indices had to be prepared to adjust the refractive index of each layer when a semi-transparent film with various reflectances would be produced.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a multilayer film which is excellent in the handling characteristic such as formability and windability even if it is a thin film by solving the above-mentioned problems.
It is another object of the present invention to provide a multilayer film which can adjust reflectance easily.
It is still another object of the present invention to provide a refractive polarizer film prepared by laminating the multilayer films of the present invention.
It is still another object of the present invention to provide a semi-transparent film prepared by laminating the multilayer films of the present invention.
Other objects and advantages of the present invention will be apparent from the following description.
According to the present invention, firstly, the above objects and advantages of the present invention can be achieved by a multilayer film comprising a first layer comprising mainly of a polyester whose main recurring unit is ethylene-2,6-naphthalene dicarboxylate and a second layer comprising mainly of a thermoplastic resin which is different from the polyester of the first layer, wherein at least one of the first and second layers contains 0.001 to 0.5 wt % of inert fine particles having an average particle diameter of 0.01 to 2 &mgr;m; the first and second layers each have a thickness of 0.05 to 0.3 &mgr;m and are laminated alternately to form a laminate comprising at least 11 layers; the laminate is oriented at least in one direction; and the second layer has a lower refractive index than the first layer at least in one direction.
Further, according to the present invention, secondly, the above objects and advantages of the present invention can be achieved by a refractive polarizer film comprising some laminates of the above multilayer films of the present invention.
Further, according to the present invention, thirdly, the above objects and advantages of the present invention can be achieved by a semi-transparent film comprising the above multilayer films of the present invention.
Still other objects and advantages of the present invention will be apparent from the following description.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The multilayer film of the present invention is a film in which a layer comprising a polymer having a high refractive index (layer A) and a layer comprising a polymer having a lower refractive index than the polymer of the layer A (layer B) are laminated alternately. A description will be given to the multilayer film of the present invention hereinafter.
The layer A in the present invention comprises a polyester whose main recurring unit is ethylene-2,6-naphthalene dicarboxylate.
The polyester may be a polymer in which ethylene-2,6-naphthalate constitutes preferably at least 85 mol %, more preferably at least 98 mol %, of the total of all recurring units.
Particularly preferably as the polyester is an polyethylene-2,6-naphthalene dicarboxylate homopolymer. The use of these polyethylene-2,6-naphthalates has such an advantage that the layer A exhibits a high refractive index after stretched.
As for the copolymer components of the above polyester, examples for the acid components illustrate aromatic carboxylic acids such as terephthalic acid, isophthalic acid and 2,7-naphthalene dicarboxylic acid except 2,6-naphthalene dicarboxylic acid; aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid and decanedicarboxylic acid;
and alicyclic dicarboxylic acids such as cyclohexane dicarboxylic acid, and examples for the glycol components illustrate aliphatic diols such as butane diol and hexane diol; and alicyclic diols such as cyclohexane dimethanol. The layer B in the present invention must have a lower refractive index than the layer A comprising polyethylene-2,6-naphthalene dicarboxylate at least in one direction. The layer B in the present invention has a refractive index which is preferably at least 0.005, more preferably at least 0.02, lower than the layer A comprising polyethylene-2,6-naphthalene dicarboxylate at least in one direction. Preferable examples of the thermoplastic resin constituting the layer B described above include a mixture of a polyester
Murooka Hirofumi
Tokuda Hiroshi
Chen Vivian
Sughrue & Mion, PLLC
Teijin Limited
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