Optical: systems and elements – Having significant infrared or ultraviolet property
Reexamination Certificate
2000-05-01
2002-06-11
Spyrou, Cassandra (Department: 2872)
Optical: systems and elements
Having significant infrared or ultraviolet property
C359S359000, C252S582000, C252S587000
Reexamination Certificate
active
06404543
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a novel infrared shielding film. More particularly, the present invention relates to an infrared shielding film which maintains excellent transmission of visible light, effectively suppresses transmission of the sunlight, exhibits excellent scratch resistance, light resistance, durability and antifouling property and are advantageously used for attaching to window panes and plastic boards for windows.
2. Description of Related Art
Plastic films have been used as films attached to window panes and plastic boards for windows for various purposes.
The sunlight coming into a room through a window pane contains ultraviolet light and infrared light in addition to visible light. Ultraviolet light contained in the sunlight causes sunburn and adverse effects of ultraviolet light on human bodies are recently mentioned. It is also well known that ultraviolet light causes degradation of packaging materials and deterioration of contents. Infrared light contained in the sunlight causes problems such as elevation of the room temperature by the light directly transmitted into the room and the efficiency of air conditioning during the summer time decreases. To prevent these undesirable phenomena, ultraviolet shielding films and infrared shielding films are attached to window panes and plastic boards for windows.
It is also generally practiced that films for preventing sight from the outside are attached to window panes and plastic boards for windows so that watching the inside of a room from the outside is made difficult. Films for preventing scattering of fragments are attached to window panes to prevent scattering of fragments of glass fractured in a disaster such as earthquake. The ultraviolet shielding films, the infrared shielding films and the films for preventing sight from the outside described above also exhibit the effect of preventing scattering of fragments.
The above films attached to window panes and plastic boards for windows (hereinafter, occasionally referred to as window films) generally have a scratch-resistant layer on the face thereof to provide the films with scratch resistance. The scratch-resistant layer is formed by coating the surface of the film with a resin of the ionizing radiation curing type such as a polyester acrylate resin, an epoxy acrylate resin, a urethane acrylate resin and a polyol acrylate resin and curing the resin.
Methods for providing windows of buildings, vehicles and refrigerated or freezing showcases with the property to reflect or absorb the heating radiation (infrared light) have been proposed to reduce heat and to save energy. For examples, films for reflection of heating radiation which have thin films of metals such as aluminum, silver and gold formed on the surface of transparent film substrates in accordance with the sputtering process or the vapor deposition process are attached to windows (Japanese Patent Application Laid-Open Nos. Showa 57(1982)-59748 and Showa 57(1982)-59749).
However, although the thin films formed in accordance with the sputtering process or the vapor deposition process have an excellent property for shielding heating radiation, these films have drawbacks in that the films has poor transparency and transmission of visible light through window panes decreases when the films are attached to window panes, that the films give reflection with metallic gloss and appearance becomes undesirable and that cost of production increases.
Recently, various infrared shielding films in which an infrared shielding layer comprising infrared shielding agents is disposed on a substrate film have been proposed to improve the above drawbacks (for example, Japanese Patent Application Laid-Open Nos. Heisei 7(1995)-100996, Heisei 8(1996)-281860, Heisei 9(1997)-108621 and Heisei 9(1997)-156025).
The infrared shielding agents used for the infrared shielding films can be divided into inorganic infrared shielding agents and organic infrared shielding agents. As the former inorganic infrared shielding agent, for example, metal oxides such as tin oxides, ATO (tin oxides doped with antimony) and ITO (indium oxides doped with tin) are well known. However, when an infrared shielding film is prepared by forming an infrared shielding layer using the oxide described above, the oxide must be used generally in an amount as great as 50 to 100 parts by weight per 100 parts by weight of a binder resin. As the result, problems arise in that workability during forming the infrared shielding layer deteriorates and that cost of production increases.
As the organic infrared shielding agent, for example, cyanine infrared shielding agents, phthalocyanine infrared shielding agents, naphthoquinone infrared shielding agents and anthraquinone infrared shielding agents are known. However, the organic infrared shielding agents have drawbacks in that these agents have inferior light resistance and durability and that these agents tend to be colored although the function of shielding infrared light is exhibited by the use in a smaller amount than that of inorganic infrared shielding agents.
From the standpoint of application, it is required for an infrared shielding film that the film shows excellent transmission of visible light and, at the same time, exhibits the function of effectively shielding light of wavelengths in the near infrared region which raises the temperature of the atmosphere.
SUMMARY OF THE INVENTION
The present invention has an object of providing an infrared shielding film which maintains excellent transmission of visible light, effectively suppresses transmission of the sunlight, exhibits excellent scratch resistance, light resistance, durability and antifouling property and are advantageously used for attaching to window panes and plastic boards for windows.
As the result of intensive studies by the present inventors to develop an infrared shielding film having the above excellent properties, it was found that the above object can be achieved by a film comprising an infrared shielding film which is prepared by coating one face of a transparent substrate film with a coating liquid which comprises a resin of the ionizing radiation curing type, a specific type of infrared shielding agent in a specific amount and, optionally, a silicone resin of the ionizing radiation curing type, followed by curing the formed coating layer by irradiation of an ionizing radiation. The present invention has been completed based on this knowledge.
The present invention provides:
(1) An infrared shielding film comprising a transparent substrate film having, on one face thereof, at least an infrared shielding layer comprising a cured product of a coating layer which comprises (A) a resin of an ionizing radiation curing type and (B) an infrared shielding agent comprising a rare earth metal in an amount of 0.1 to 20 parts by weight per 100 parts by weight of the resin of an ionizing radiation curing type;
(2) An infrared shielding film described in (1), wherein the coating layer further comprises (C) a silicone resin of an ionizing radiation curing type;
(3) An infrared shielding film described in any of (1) and (2), wherein the infrared shielding layer has a thickness of 0.5 to 10 &mgr;m; and
(4) An infrared shielding film described in any of (1), (2) and (3), wherein the resin curable by ionizing radiation of component (A) comprises a photopolymerizable prepolymer as a basic component.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The transparent substrate film used for the infrared shielding film of the present invention is not particularly limited and a suitable film can be selected from various types of transparent plastic films in accordance with the situation. Examples of the transparent plastic film include films of polyolefin resins such as polyethylene, polypropylene, poly-4-methylpentene-1 and polybutene-1; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polycarbonate resins; polyvinyl chloride resins; polyphenylene sulfide resins; polyether sulfone res
Maruoka Shigenobu
Shoshi Satoru
Frishauf Holtz Goodman & Chick P.C.
Lintec Corporation
Maxie Christopher S
Spyrou Cassandra
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