Stock material or miscellaneous articles – Surface property or characteristic of web – sheet or block
Reexamination Certificate
1999-08-06
2002-09-03
Thibodeau, Paul (Department: 1773)
Stock material or miscellaneous articles
Surface property or characteristic of web, sheet or block
C428S423100, C428S424800, C428S515000, C428S516000, C264S246000, C264S247000
Reexamination Certificate
active
06444317
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a novel decorative film for use in plastics molding, a process for preparing the decorative film and an injection-molded part obtained by use of the decorative film.
(2) Description of Background Art
As automobile parts, household appliance parts and general industrial parts, plastics molded parts, particularly polypropylene resin molded parts have widely been used in the art. For the purpose of imparting decoration, durability etc. to the polypropylene resin molded part, a coating composition for use in plastics is coated onto the surface of the molded part. However, a coating film formed from the coating composition for use in plastics generally shows poor adhesion properties to the polypropylene resin. On the other hand, a primer is coated for the purpose of improving adhesion properties.
As a method of coating the plastic coating composition onto the above plastics molded part, an electrostatic spray coating is employed so as to improve a coating efficiency with the result that an unsatisfactory coating efficiency raises such problems that a product cost is high and that non-uniform coating on a curved surface area provides poor properties in adhesion properties and finished properties of the plastic coating film.
For the purpose of solving the above problems, for example, Japanese Patent Application Laid-Open Nos. 203048/83, 123469/88, 216717/88, 52416/96, and Japanese Patent Publication No. 2550/96 etc. disclose a method of coating a pigmented coating composition onto the surface of a synthetic resin film to obtain a pigmented film, followed by integrally molding by use of the pigmented film and a molding resin so as to apply the pigmented film onto a molded part and molded products obtained therefrom. Of the above prior art, Japanese Patent Publication No. 2550/96 discloses, as pigmented coating composition, lacquer type coating compositions containing, as base resins, acrylic resin and fluorocarbon resin. However, coating of the above coating compositions onto a polypropylene resin film results poor adhesion properties to the polypropylene resin film to be impractical.
As above described, adhesion of a coating film for use in plastics or a pigmented coating film to polypropylene resin is difficult. For the purpose of overcoming the above difficulty, an attempt to coat a known isocyanate-curing type primer onto the polypropylene resin film has been made. However, the use of the above film in the case where plastics is fabricated to a molded part having high degree of deformation, for example, a bumper results such problems as to develop coating film deffects such as cracks, peeling, etc. of the primer coating film on a three dimensional curved surface area showing high elongation of the molded part. Further, the use of the above primer raised such a problem that an electrostatic coating of a topcoating composition onto the surface of the primer shows a poor coating efficiency.
On the other hand, Japanese Patent Application Laid-Open Nos. 123469/88 and 52416/96 disclose that the pigmented film used therein is such that a metallic base coat is coated on the surface of a coat film such as a transparent film obtained by coating a solution obtained by dissolving a polymer in an organic solvent onto the surface of a substrate, followed by drying and evaporating the organic solvent and stripping from the substrate, a transparent film obtained by casting a solution of a polymer onto a substrate followed by stripping from the substrate or the like to form a metallic coating film.
However, the above pigmented film is a cast film and has such disadvantages that fabrication to a film having a uniform film thickness is difficult and that the fabrication takes a long time. The use of an isocyanate-curing type base coat coating composition and melamine-curing type base coat coating composition in the above metallic base coat, as known as a base coat for use in automobiles, when fabricated to a molded part having high degree of deformation, for example, a bumper results such problems as to develop coating film defects such as cracks, peeling, etc. of the primer coating film on a three dimensional curved surface area showing high elongation of the molded part.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a decorative film for use in plastics molding, capable of being uniformly and easily joined onto a plastic molded product having a curved surface area and showing good adhesion properties to both plastic material and topcoating film and good finished appearance.
It is another object of the present invention to provide a decorative film for use in plastics molding, capable of being uniformly and easily joined onto a plastic molded product having a curved surface area, showing good adhesion properties to both plastic material and topcoating film, good finished appearance and electrostatic coating workability, particularly high electrostatic coating efficiency of metallic coating composition and high electrostatic coating efficiency of clear coating composition.
It is another object of the present invention to provide a decorative film for use in plastics molding, capable of being uniformly and easily joined onto a plastic molded product having a curved surface area, and showing good adhesion properties to plastic material and good adhesion properties between a transparent film and a pigmented layer.
It is another object of the present invention to provide a plastic molded part showing good finished appearance.
In a first aspect, the present invention provides a decorative film for use in plastics molding and used for obtaining an integrally molded product with the decorative film by a process which comprises setting the decorative film on an inner side of an injection mold and subjecting a molding polyolefin based resin to an injection molding, said decorative film being a laminate film prepared by outwardly and successively laminating a polyolefin film layer, a primer layer, optionally a topcoating layer and a releasable layer, said primer layer being a coating film formed from an isocyanate-curing type resin composition containing (A) a hydroxyl group-containing resin having a hydroxyl number of 30 to 200 KOH mg/g on an average and a weight average molecular weight of 1000 to 80000, (B) a polyolefin based resin and (C) a (blocked)polyisocyanate compound in such mixing amounts that a number of the isocyanate group in the component (C) is in the range of 0.1 to 0.9 per one hydroxyl group in the component (A) and that the component (B) is in the range of 1 to 90% by weight based on a total weight of the components (A), (B) and (C), and having a static glass transition temperature of 20 to 70° C., an elongation of 10% or more and a tensile strength of 0.5 kgf/mm
2
or more; a process for preparing a decorative film for use in plastics molding, which process comprises coating an isocyanate-curing type coating composition containing (A) a hydroxyl group-containing resin having a hydroxyl number of 30 to 200 KOH mg/g on an average and a weight average molecular weight of 1000 to 80000, (B) a polyolefin based resin, (C) a (blocked)polyisocyanate compound and (E) an organic solvent in such mixing amounts that a number of the isocyanate group in the component (C) is in the range of 0.1 to 0.9 per one hydroxyl group in the component (A) and that the component (B) is in the range of 1 to 90% by weight based on a total weight of the components (A), (B) and (C) onto one side of a polyolefin based film layer, followed by drying at normal temperature or by heating to form a primer layer having a static glass transition temperature of 20 to 70° C., an elongation of 10% or more and a tensile strength of 0.5 kgf/mm
2
or more; and an injection-molded part obtained by setting the decorative film as claimed in claim 1 on an inner side of an injection mold so that the polyolefin film layer can join onto an outer surface of a resin molded product, followed by carrying out an injection moldi
Haruta Naoya
Kato Tadahiro
Seike Koichi
Tomiyama Takesi
Fisher Christen & Sabol
Jackson Monique R.
Kansai Paint Co. Ltd.
Thibodeau Paul
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