Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-01-31
2002-02-19
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S847000
Reexamination Certificate
active
06348537
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a coating agent comprising a polyfunctional (meth)acrylate monomer, and if desired, a monofunctional (meth)acrylate monomer and colloidal silica having a specific form, and a resin molded article having a coated layer excellent in abrasion resistance, weather resistance, adhesion with a substrate, and the like, obtained by hardening the coating agent.
2. Description of the Background
A resin molded article produced from polymethyl methacrylate, polycarbonate, polystyrene, AS resin and the like is used in various fields utilizing not only lighter weight and more excellent impact resistance as compared with glass products but also various merits such as excellent transparency, easy molding work property and the like.
However, on the contrary, these resin molded articles are deficient in abrasion resistance of the surface, therefore, tend to receive injury on the surface by contact, friction, scratch and the like with other hard substance, and consequently, commercial value thereof may be remarkably lowered by this injury, or the resin molded articles may become unusable in a short period of time. Therefore, improvement of abrasion resistance of the surface of these resin molded articles is desired strongly.
As the method for improving this point, JP-A Nos. 53-102936, 53-104638 and 54-97633, for example, disclose a method in which a hardening solution comprising a compound having a plurality of (meth)acryloyloxy groups in the molecule is applied on a molded article, and it is hardened by heat or an active energy ray such ultraviolet ray and the like, to obtain a molded article having excellent abrasion resistance. This method has merits that the hardening solution is relatively cheap, and excellent also in productivity. However, since the hardened coated film is made of an organic substance, the abrasion resistance of the coated molded article has a limitation.
On the other hand, as a method for imparting more hither abrasion resistance to a molded article, JP-A Nos. 48-26822 and 59-64671, for example, disclose a method in which an alkoxysilane compound is applied on the surface of a plastic molded article, and hardened with heat. Further, JP-A No. 56-106969, for example, discloses a method in which a mixture of colloidal silica and an organic resin is applied on the surface of a plastic molded article, and is hardened with heat. However, in these method, a drying process is necessary since a solvent is used, and energy consumption amount is large and a long period of time is required since hardening with heat is necessary, leading to industrial demerits. Moreover, evaporation of a solvent in processes for hardening and drying a coated film is not preferable also from the standpoint of protection of the global environment.
As a method for improving these problems, JP-A Nos. 57-131214 and 3-56514, for example, disclose a method in which a hardening solution comprising a compound having a plurality of (meth)acryloyloxy groups in the molecule, and colloidal silica is applied on a molded article, and hardened by an active energy ray such as ultraviolet ray and the like to obtain a coated molded article having high abrasion resistance. However, in this method, a coated molded article has a problem in weather resistance, and a coated molded article excellent in balance between abrasion resistance, weather resistance and adhesion of a coated layer with a substrate can not be obtained.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a colloidal silica-containing coating agent which can form on the surface of a molded article a coated layer having excellent appearance and hardness and being excellent in balance between abrasion resistance, weather resistance and adhesion with a substrate and which can be formulated without no solvent, and a resin molded article having a coated layer formed by hardening this coating agent.
The present inventors have intensively studied for attaining the above-mentioned object, and resultantly, found that extremely excellent effects can be obtained by using colloidal silica having a specific form, leading to completion of the present invention.
Namely, the coating agent of the present invention is a coating agent comprising
50 to 99 parts by weight of a monomer or monomer mixture (M) composed of 50 to 100% by weight of a polyfunctional (meth)acrylate monomer (m-1) having at least two (meth)acryloyloxy groups in the molecule and 0 to 50% by weight of a monofunctional (meth)acrylate monomer (m-2) co-polymerizable with the monomer (m-1), and
1 to 50 parts by weight of colloidal silica, wherein the colloidal silica contains colloidal silica in a narrow and long form having an average diameter of 5 to 20 nm and an average length of 40 to 300 nm in an amount of 5 to 100% by weight based on the total colloidal silica weight.
Further, the resin molded article of the present invention is a resin molded article having a coated layer formed by hardening the coating agent of the present invention.
In the present invention, “(meth)acryloyl” means “acryloyl and/or methacryloyl”.
REFERENCES:
patent: 57-131214 (1982-08-01), None
patent: 1-317115 (1989-12-01), None
patent: 3-56514 (1991-03-01), None
patent: 4187512 (1992-07-01), None
patent: 5-179157 (1993-07-01), None
patent: 5-297588 (1993-11-01), None
patent: 7-118008 (1995-05-01), None
patent: 8-114915 (1996-05-01), None
Kawai Osamu
Sawano Tetsuya
Sugamoto Hideyuki
Cain Edward J.
Mitsubishi Rayon Co. Ltd.
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