Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1988-11-07
1990-12-11
Gallagher, John J.
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
156235, 156236, 156240, 428204, B32B 1700
Patent
active
049768050
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an improvement of a process for the manufacture of decorative intermediate films for use in laminated glass sheets such as windshields of automotive vehicles.
BACKGROUND ART
As is well known in the art, the windshields for automotive vehicles are comprised of two sheets of glass with a thermoplastic substance, typically polyvinylbutyral intermediate film interposed therebetween bonded integral into one sheet of glass so that the scattering of broken glass pieces resulting from the damage of the windshield can be prevented.
Frequently, a portion of an intermediate film is colored so that the windshields may have the additional function of sun visors.
Of the various methods for dyeing decorative intermediate films for laminated glass sheets, a transfer method (disclosed, for instance in Japanese Patent Publication Nos. 55-14821 and 57-29426) has been used. According to this method, a transfer sheet, which is extended over a surface of a substrate and is printed with an ink capable of dyeing an intermediate film, is superposed over an intermediate film, and then is subjected to a heating and pressure application process so that the printing ink is transferred over the intermediate film. After the separation of the substrate and ageing or only after ageing, the printed pattern is transferred over the surface of the intermediate film.
However, according to the above-described method, in the process of applying heat and pressure to an intermediate film in the transfer method, it frequently occurs that fine projections and recesses formed over the surface of the intermediate film disappear so that this method has the defect that air bubbles tend to be left when the intermediate film thus obtained is laminated to a sheet of glass. That is, unless such fine projections and recesses over the surface of the intermediate film are left in order to carry out the deairing operation when the glass sheets are laminated, defective articles containing air bubbles are frequently produced, and consequently, the yield is decreased.
Furthermore, in the conventional processes for manufacture of intermediate films, the penetration of ink is limited to the portion immediately adjacent to the surface of a glass sheet so that the overall surface of the intermediate film is not satisfactorily dyed, and consequently, there arises the problem that the outer appearance of the finished product is degraded. That is, in the case of forming a coloring pattern, the conventional processes are limited in their capability of forming a high-quality printed pattern (for instance, a vignette pattern).
DISCLOSURE OF THE INVENTION
An object of the present invention is therefore to provide a process for the manufacture of intermediate films which are attractively and uniformly dyed and have a high degree of decorative capability for laminated glass sheets.
A process for manufacture of intermediate films for laminated glass sheets in accordance with the present invention comprises the following steps:
(a) forming a transfer sheet having a desired printing pattern by printing a transfer sheet substrate with an ink capable of dyeing an intermediate film made of a thermoplastic resin for a laminated glass sheet;
(b) applying to a printed pattern surface, and/or the surface of the transfer sheet thus obtained, a solvent capable of softening to some extent the vehicle of the printing ink and the intermediate film;
(c) superposing the printed pattern surface over the intermediate film through the coating surface of the solvent and then pressing them at a low temperature below a glass transition point of the intermediate film, thereby transferring and impregnating the printed pattern over and into the surface of the intermediate film; and
(d) separating the transfer sheet substrate from the intermediate film and drying the intermediate film, thereby obtaining a decorative intermediate film used in a laminated glass sheet.
According to the present invention, intermediate films having fine projections and
REFERENCES:
patent: 3918895 (1975-11-01), Mizuno
patent: 4173672 (1979-11-01), Mannheim
patent: 4642255 (1987-02-01), Diabak
patent: 4770732 (1988-09-01), Steelman
Fukuda Tetsuya
Ishii Sumio
Kani Nobumoto
Dai Nippon Insatsu Kabushiki Kaisha
Falasco Louis
Gallagher John J.
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