Stock material or miscellaneous articles – Composite – Of polycarbonate
Reexamination Certificate
1998-08-13
2002-05-07
Thibodeau, Paul (Department: 1773)
Stock material or miscellaneous articles
Composite
Of polycarbonate
C428S429000, C428S430000, C428S447000, C428S448000, C427S487000, C427S492000, C427S503000, C427S515000, C427S163100, C427S164000, C427S412100, C264S001360
Reexamination Certificate
active
06383641
ABSTRACT:
The present invention relates to a transparent coated molded product having a transparent cured material layer excellent in abrasion resistance, transparency and weather resistance, which comprises a cured material layer derived from an active energy ray (particularly ultraviolet light)—curable coating agent and a silica layer derived from a coating agent of polysilazane or a coating agent containing polysilazane, on a transparent synthetic resin substrate, and a method for producing the transparent coated molded product.
Recently, a transparent synthetic resin material has been used as a transparent material in place of glass. Particularly, an aromatic polycarbonate type resin is excellent in shatter resistance, transparency, lightness and processability, and is used as a transparent material of large area for an outer wall, an arcade and the like. Also, a transparent synthetic resin material is used for vehicles such as automobiles partly in place of glass (hereinafter referred to as “inorganic glass”). However, as a substitute for glass, the transparent synthetic resin material has a defect of easily losing its transparency because it is liable to be damaged or to be abraded due to its insufficient hardness of the surface. Heretofore, many attempts have been made to improve resistance to scuffing or abrasion resistance of an aromatic polycarbonate type resin. One of most general methods is to obtain a molded product having a transparent cured material layer excellent in resistance to scuffing by coating a polymerization-curable compound having at least 2 polymerizable functional groups such as an acryloyl group in one molecule on a substrate and curing by heat or an active energy ray such as ultraviolet light. According to this method, a coating composition is relatively stable, and productivity is excellent since curing can be made by ultraviolet light, and when a molded product is bending-processed, cracks do not occur on a cured coating layer and resistance to scuffing and abrasion resistance of the surface of the layer are improved. However, since the cured coating layer comprises an organic material only, the level of resistance to scuffing of the surface of the layer is limited.
On the other hand, as a method for imparting a higher surface hardness to a substrate, there is a method comprising coating a metal alkoxide compound on a substrate and curing. A silicon type compound is widely used as a metal alkoxide compound, and a cured coating layer excellent in abrasion resistance can be formed. However, since adhesiveness between the cured coating layer and a substrate is poor, there is a defect of causing peeling or cracks.
As a method for improving these technical defects, there is a method comprising coating a mixture of a compound having an acryloyl group and colloidal silica on a substrate and curing the coating with an active energy ray such as ultraviolet light to form a transparent cured material layer excellent in resistance to scuffing (JP-A-61-181809). By using colloidal silica and a polymerization-curable compound in combination, a considerably high surface hardness and a satisfactory productivity can be achieved. However, still poor in respect of its surface resistance to scuffing as compared with the above mentioned method comprising coating a metal alkoxide compound on a substrate and curing.
Further, there is known a method of using polysilazane in place of the above mentioned silicon type metal alkoxide compound, i.e. a method of coating polysilazane on a substrate and curing by heat (JP-A-8-143689). It is considered that polysilazane causes a condensation reaction or an oxidation reaction in the presence of oxygen and is converted to silica (silicon dioxide) which may contain a nitrogen atom, and finally forms a silica layer containing substantially no nitrogen atom. The silica layer derived from polysilazane has a high surface hardness. However, this layer is poor in adhesiveness between the layer and a substrate in the same manner as in the case of using a metal alkoxide compound, and has a defect of easily causing peeling or cracks.
Still further, there is known a method of forming a silica surface layer by forming a protective layer on a plastic layer and coating polysilazane solution on its surface (JP-A-9-39161). The protective layer is provided to prevent the plastic film from being attacked by the solvent of the polysilazane solution.
It is known that the surface of the silica layer formed from polysilazane has abrasion resistance. However, the present inventors have found that surface properties such as abrasion resistance and resistance to scuffing on the surface of this silica layer vary depending on the material of its lower layer. It is considered that this is because the surface properties are influenced by adhesiveness between the silica layer and its lower layer and abrasion resistance of the surface of the lower layer in contact with the silica layer.
The present inventors have studied the material of a lower layer which imparts high surface properties to a silica layer surface, and have found a lower layer material having a specific material quality and surface properties. This lower layer material has a high adhesiveness to a silica layer, and also has a sufficient adhesiveness to a substrate. That is, the present inventors have discovered a transparent synthetic resin molded product having a transparent cured material layer having a surface abrasion resistance equivalent or close to glass and having a sufficient adhesiveness to an inner layer and also to a substrate although an outermost layer is an inorganic material layer. Thus, the present invention resides in the following molded product and the following methods of producing the same.
A transparent coated molded product comprising a transparent synthetic resin substrate and two or more transparent cured material layers provided on at least one part of the surface of the transparent synthetic resin substrate, wherein an inner layer in contact with the outermost layer of the two or more transparent cured material layers is an abrasion-resistant layer which is a cured material of an active energy ray-curable coating agent (A) containing a polyfunctional compound (a) having at least 2 active energy ray-curable polymerizable functional groups and the outermost layer is a silica layer which is a cured material of a curable coating agent (B) of polysilazane or a curable coating agent (B) containing polysilazane.
A method for preparing a transparent coated molded product comprising a transparent synthetic resin substrate and two or more transparent cured material layers provided on at least one part of the surface of the transparent synthetic resin substrate, wherein an inner layer in contact with the outermost layer of the two or more transparent cured material layers is an abrasion-resistant cured material layer of an active energy ray-curable coating agent (A) containing a polyfunctional compound (a) having at least 2 active energy ray-curable polymerizable functional groups and the outermost layer is a silica layer of a cured material of a curable coating agent (B) of polysilazane or a curable coating agent (B) containing polysilazane, the method comprising forming a cured material layer of the coating agent (A), forming an uncured material layer of the coating agent (B) on the surface of the cured material layer of the coating agent (A) and then curing.
A method for preparing a transparent coated molded product comprising a transparent synthetic resin substrate and two or more transparent cured material layers provided on at least one part of the surface of the transparent synthetic resin substrate, wherein an inner layer in contact with the outermost layer of the two or more transparent cured material layers is an abrasion-resistant cured material layer of an active energy ray-curable coating agent (A) containing a polyfunctional compound (a) having at least 2 active energy ray-curable polymerizable functional groups and the outermost layer is a silica layer of a cured material
Asakura Junko
Higuchi Toshihiko
Kondou Satoshi
Shibuya Takashi
Yamamoto Hirotsugu
Asahi Glass Company Ltd.
Jackson Monique R.
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