Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2000-06-05
2002-04-16
Parker, Fred J. (Department: 1762)
Stock material or miscellaneous articles
Composite
Of silicon containing
C428S448000, C526S259000, C526S261000, C526S279000, C526S328000
Reexamination Certificate
active
06372355
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to ultraviolet absorptive laminated resinous articles which exhibit minimized coloring or deterioration induced by ultraviolet radiation, with satisfactory interlayer adhesion and improved abrasion resistance and weatherability.
2. Description of the Prior Art
Resinous films, resinous sheets, resin plates, and other resinous articles (hereinafter may be inclusively referred to as “resin plate”) made of, for example, polycarbonates are excellent in transparency, impact resistance, heat resistance, flame resistance, and other properties. These resinous articles are in wide use for road constructive materials and building materials and are expected to be applied to other uses. However, the application of the resin plates is restricted since the resin plates are not so effective as metal plates, glass plates and the like in terms of surface hardness, abrasion resistance, solvent resistance and other surface properties. Strong demands have been therefore made to improve the surface properties of such base resin plates. A possible solution to improve the surface properties is a process of -coating the surface of a base resin plate with a surface treatment agent. Such a surface treatment agent include, for example, an ultraviolet-curable acrylic compound, a thermosetting melamine resin, or a thermosetting organopolysiloxane resin which form a hard resin layer on a surface of a base resin plate.
Of these proposed processes, coating the surface of the base resin plate with a thermosetting organopolysiloxane resin that provides typically high surface hardness and chemical resistance. Specifically, by coating the surface of a base resin plate with a partially hydrolyzed condensate of an organotrialkoxysilane alone, with a partially hydrolyzed condensate between a tetraalkoxysilane and an organotrialkoxysilane, or with a partially hydrolyzed condensate of an organotrialkoxysilane containing colloidal silica, the coated resin plate can be obtained with a satisfactory surface hardness. Such a coating constituent of the surface hard resin layer exhibits a satisfactory adhesion to a base resin plate when a base resin plate is made of a poly(methyl methacrylate) resin. However, when coating the surface of polycarbonate resin with these surface treatment agents, the coated hard resin layer tend to decrease its adhesion to the base resin plate and may be peeled from the base resin plate.
To improve the adhesion of such a hard resin layer, Japanese Examined Patent Application Publications No. 63-5155 and No. 63-52668, for example, each propose a technique of preliminarily treating the surface of a polycarbonate resin plate to form a primer layer. Indeed, the adhesion of the surface hard resin layer is improved by forming the surface resin layer on the primer layer, according to this process.
A second problem which generally arises is an insufficient weatherability, particularly deterioration and coloring of the resin plate upon exposure to ultraviolet radiation. An initial adhesion of the hard resin layer is improved by the aforementioned technique, but both the hard resin layer and the primer layer have no property to absorb ultraviolet radiation. Therefore transmitted ultraviolet radiation deteriorates the surface of the resin plate thereby introduces other problems such as deterioration of the improved adhesion of the hard resin layer and deterioration of weatherability such as coloring or decrease in strength. To prevent such ultraviolet radiation that deteriorates the resin from reaching the surface of the resin plate, for example, Japanese Examined Patent Application Publication No. 60-53701 and Japanese Examined Patent Application Publication No. 2-37938 each proposes a technique of adding an ultraviolet absorbent to components of a surface layer such as a primer layer or a surface hard resin layer, and absorbing the ultraviolet radiation by ultraviolet absorbent added layer. In addition, a variety of techniques to improve the composition of the surface hard resin layer or the primer layer have been proposed in order to prevent, for example, deterioration in solvent resistance of the surface layer induced by the added ultraviolet absorbent and to improve the adhesion of the surface layer to a base resin layer (e.g., Japanese Examined Patent Application Publication No. 1-7582, Japanese Examined Patent Application Publication No. 1-32246, Japanese Examined Patent Application Publication No. 1-18944, and Japanese Examined Patent Application Publication No. 2-37938). These techniques can prevent the ultraviolet-induced deterioration of the resin plate surface to some extent and can provide a somewhat satisfactory adhesion.
However, large amounts of an ultraviolet absorbent must be added to the surface hard resin layer and the primer layer in order to provide complete blockage of ultraviolet radiation within these layers. As a result, the surface hard resin layer and/or the primer layer is colored or is hazed to decrease the transparency of the surface hard resin plate, which transparency distinguishes the surface hard resin plate from others. In addition, the added ultraviolet absorbent bleeds out from the layer to deteriorate the appearance of the resin plate or to decrease the abrasion resistance. The bleed-out of the ultraviolet absorbent will result in a deteriorated interlayer adhesion between the surface hard resin layer and the primer layer or between the primer layer and the base resin layer. The ultraviolet absorbent itself does not have a significantly high hardness, and containing large amounts of the ultraviolet absorbent in the hard resin layer will decrease the hardness of the layer. Specifically, without the addition of an ultraviolet absorbent, the surface of the resin plate is deteriorated and the adhesion of the surface hard resin layer is decreased due to ultraviolet radiation. In contrast, the addition of an ultraviolet absorbent results in coloring or deterioration of the surface hardness. These problems have not been solved concurrently.
As a potential solution to these problems, Japanese Unexamined Patent Application Publication No. 9-3135 and Japanese Unexamined Patent Application Publication No. 10-34840, for example, propose the use of an acrylic resin in a surface layer, which acrylic resin is obtained by copolymerizing an acrylic monomer with a reactive ultraviolet absorbent. These techniques allow the use of large amounts of an ultraviolet absorbent. However, all the acrylic resins obtained by the copolymerization with an ultraviolet absorbent are thermoplastic and are insufficient in hardness as a coating layer for surface protection and have an insufficient abrasion resistance. In addition, satisfactory hot water resistance and weatherability cannot be significantly obtained.
Japanese Unexamined Patent Application Publication No. 4-106161 discloses a process for improving the heat resistance, abrasion resistance, surface hardness, surface gloss, and other properties. The process includes the steps of copolymerizing a monomer having an ultraviolet absorptive group to yield a copolymer, coating the surface of a base resin plate with the copolymer as a primer layer, and coating the surface of the primer layer with an organopolysiloxane as a hardcoat layer. The publication also discloses that a monomer having an ultraviolet stable group is preferably copolymerized, in addition to the monomer having an ultraviolet absorptive group.
According to these techniques, however, the constitutive ultraviolet absorptive copolymer is thermoplastic and the primer layer has an insufficient weatherability and a low abrasion resistance even if the surface of the primer layer is coated with a hardcoat layer. As a result, the hardcoat layer has also an insufficient weatherability and a low abrasion resistance. In addition, the adhesion between the primer layer and the hardcoat layer after a hot water resistance test or a weathering test is insufficient and a satisfactory interlayer adhesion cannot be
Aoyama Takahiro
Nishida Toshifumi
Noda Nobuhisa
Nippon Shokubai Co. , Ltd.
Parker Fred J.
Tsoy Elena
Wenderoth Lind & Ponack LLP
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