JP2002216573A - Key sheet and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a key sheet and its manufacturing method having an advantage for mass production, in which a display having a mirror-like surface with metallic luster and tinted with a variety of colors, including red, blue, and green, is arranged on the back of a resin film at a low cost. SOLUTION: The resin film having the display is integrally formed on the upper surface of a resin button to form the key sheet, the display formed by forming a thin metal layer on the back of the resin film via a transparent colored layer and further laminating a protecting layer on the back of the metal thin layer. In the manufacturing method of the key sheet, the metal thin layer is formed on one surface of the resin film via the transparent layer by dry plating, and the protecting layer is formed on a prescribed position on the metal thin layer by coating, which is followed by the removing of the metal thin layer and transparent colored layer using an etching solution to form the display. Then, the above laminated layers are deformed into the same shape as that of the upper surface of the button in the way that the display of the film is on the back of the layers, and the deformed part is filled with the resin to integrally form the button.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact and lightweight key sheet used for various portable devices such as a mobile communication terminal such as a mobile phone and a car phone, and a method of manufacturing the key sheet.

[0002]

2. Description of the Related Art Conventionally, in a key switch used in a portable device, a key sheet of a push button switch formed by a combination of a resin film and a resin button made of a thermoplastic resin has attracted attention because of its thinness and light weight.

A conventional key sheet is, as shown in FIG.
A display portion 2 of predetermined characters, numerals, symbols, symbols, etc. is formed on the front and back surfaces of the resin film 1 and is integrated with a resin button 4 made of a thermoplastic resin.
There are various colors such as achromatic colors such as black and gray, chromatic colors such as red, blue and green, and metallic colors such as gold and silver. As a method of manufacturing these key sheets, a method of integrally molding a resin film and a thermoplastic resin having a display portion by injection molding,
JP-A-54-154461, JP-B-7-5465.
No. 6 and the like.

[0004] In recent years, there have been many demands for specular metallic luster designs in colors such as red, blue and green. Mirror-like metallic luster designs have been embodied in several ways. One is a method of printing an ink containing a metallic pigment or a pearl pigment using a metal powder such as an aluminum powder on a resin film. One is a hot stamping method in which a metal foil such as aluminum is transferred to a resin film.

[0005]

However, each of the above methods has its own problems. The former method of printing an ink containing a metallic pigment or a pearl pigment using a metal powder such as an aluminum powder on a resin film includes red, blue,
It had a metallic color with a color such as green, but did not have a mirror-like metallic luster. In the latter hot stamping method for transferring a metal foil such as aluminum to a resin film, the transfer layer of the metal foil could not follow the elongation of the resin film, causing cracks and the like.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a key sheet having a mirror-like metallic glossy display portion of red, blue, green or the like on the back surface of a resin film. An object of the present invention is to provide a manufacturing method thereof. That is, on the back surface of the resin film, a metal thin film layer is formed via a transparent coloring layer, and further, on the back surface of the metal thin film layer, a resin film having a display portion on which a protective layer is laminated is integrated with the upper surface side of the resin button. It is a key sheet that has been transformed. Furthermore, the transparent coloring layer is a key sheet made of melamine-based ink.

A metal thin film layer is formed on one side of the resin film via a transparent coloring layer by dry plating.
After forming a protective layer at a desired position of the metal thin film layer by coating, the metal thin film layer and the transparent coloring layer are removed with an etching solution to form a display portion, and then the display portion of the resin film is on the back side. Thus, this is a method of manufacturing a key sheet in which the button is integrated into the button by deforming the button into the same shape as the upper surface side of the button and filling the deformation with resin.

Further, the dry plating process is a method for manufacturing a key sheet, which is a vapor deposition process. Further, the transparent colored layer formed on one side of the resin film is a layer made of melamine-based ink, and is a method for manufacturing a key sheet in which the transparent colored layer is removed using an acidic etching solution as an etching solution. Further, there is provided a method for manufacturing a key sheet in which the acidic etching solution is a sulfuric acid etching solution.

When a layer made of melamine-based ink is used for the transparent coloring layer of the present invention, it can be removed with an acidic etching solution. For example, an acidic solution such as sulfuric acid, chromic acid, nitric acid, hydrochloric acid, and phosphoric acid, or a mixed solution including several kinds of acids such as a mixed solution of sulfuric acid and chromic acid can be used. Above all, it can be easily removed with sulfuric acid etching solution

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A typical embodiment of the present invention will be described with reference to the drawings. In the key sheet of the present invention, as shown in FIG. 1, a metal thin film layer 6 is formed on the back surface of a resin film 1 via a transparent coloring layer 5, and a protective layer 7 is further laminated on the back surface of the metal thin film layer. A resin film having a display portion on which a decoration layer 8 is formed as necessary is deformed into the same shape as the upper surface side of the resin button 4 and is integrated with the resin button.

The transparent colored layer of the present invention may be any as long as it is in close contact with the resin film or the metal thin film layer and can be removed with an etching solution. Examples of the material include melamine, such as polyester / melamine, polyacryl / melamine, polyurethane / melamine, and melamine, butadiene, polyethyleneimine, titanate, modified polyolefin, aromatic polyester, and aliphatic polyester ink. Can be Among them, melamine-based inks are preferable because they can be easily removed with an acidic etching solution.

The resin film of the present invention only needs to have flexibility, and its composition, type, elastic modulus, color tone, and the like are not limited. For example, a resin film using a known technique such as a casting method, an extrusion method, a calendar method, and a stretching method can be appropriately selected and used. Specific examples include olefin-based films, vinyl-based films, fluorine-based films, polycarbonate-based films, acetate films, polyester-based films, polyamide films, ionomer films, and polyimide films. As the transparency of the resin film of the present invention, those having a haze (cloudiness value) of 4% or less are optimal, and a fluorine-based film, a polyester-based film, a polycarbonate-based film and the like are preferable.

The metal thin film layer of the present invention is preferably a low-cost thin film layer made of a metal such as aluminum, chromium, nickel, titanium, tungsten, silicon, gold, silver, copper, tin, and zinc. Is preferably about 10 to 60 nm.

The resin button of the present invention is not limited in its composition, type, elastic modulus, color tone, etc., but may be appropriately selected from, for example, thermoplastic resins, thermoplastic elastomers, curable resins and crosslinked rubbers. Can be used. Among them, it is preferable to use a thermoplastic resin having good moldability. If a translucent resin is used, a key sheet that emits light when illuminated from the back surface is obtained. Specifically, polycarbonate resin, polyester resin, fluorine resin, acrylic resin, acrylonitrile butadiene.
Examples thereof include styrene resin, acrylonitrile / styrene resin, acrylonitrile / chlorinated polyethylene / styrene resin, and the like, and polycarbonate resin is preferable in terms of rigidity, marketability, heat resistance, cost, and the like.

The decorative layer of the present invention is a layer made of an ink composed of a thermosetting resin or a thermoplastic resin, or an ink obtained by mixing a thermoplastic resin and a thermosetting resin, and is to be welded at the time of molding a resin button. Thus, the adhesive strength between the decorative layer and the resin button can be obtained.

Further, in the manufacturing method of the present invention, as shown in FIG. 2, a metal thin film layer 6 is formed on one surface of a resin film 1 by dry plating with a transparent coloring layer 5 interposed therebetween. After a protective layer 7 is formed at a desired position by coating (1), the metal thin film layer and the transparent coloring layer are removed with an etching solution (2), and a decorative layer 8 is formed as necessary to form a display section. 2 (3), and then the resin film is deformed into the same shape as the upper surface of the button so that the display portion of the resin film is on the back side (4). This is a method for producing the sheet (5).

The metal thin film layer is preferably formed by a dry plating process. As the dry plating process, for example, plating, vapor deposition, ion plating, thermal spraying, or the like can be used. Above all, the treatment by vapor deposition is most preferable from the viewpoint of the moldability of the thin film.

An embodiment of the present invention will be described below. Note that all members such as resin films and inks described in the examples are representative ones, and are not limited to these.

[Example 1] 50 μm thick sheet formed by biaxial stretching
After completely removing dirt and foreign matter from the surface of the polyester film of m, a melamine ink was applied on the surface of the roll to form a transparent colored layer. At this time, the color of the transparent coloring layer is blue, the thickness is 1 μm to 3 μm, and attention is paid to scratches and the like. Then, the metal thin film layer of aluminum was vapor-deposited with the batch-type wind-up vapor deposition machine. At this time, the thickness of the metal thin film layer was 40 nm.

The resin film on which the metal thin film layer was formed via the transparent coloring layer was cut into an appropriate size, and a character type protective layer was formed by printing at a desired position with a polyester ink. Alkali etching processing of the aluminum metal thin film layer was performed with an aqueous sodium hydroxide solution.
The alkali etching process is based on a known method. Then, the acid etching process of the transparent coloring layer was implemented with the heated sulfuric acid aqueous solution. After neutralization, sufficient washing and drying were completed, a decorative layer was formed by printing with a polycarbonate-based ink.

The resin film is deformed into a shape on the upper surface side of the resin button by a mold, and this resin film is inserted into an injection molding machine, and a polycarbonate resin which is a thermoplastic resin is injection-molded. The buttons were integrated. Finally, the outer periphery of the integrated key sheet was cut by punching, and a key sheet of a display portion exhibiting a blue mirror-like metallic luster in the form of a cut letter was formed on the back surface of the resin film.

[0021]

Example 2 50 μm thick sheet formed by biaxial stretching
After completely removing dust and foreign matter on the surface of the polyester film of m, a polyacryl / melamine ink was applied using a gravure printing machine to form a transparent colored layer. At this time,
The color of the transparent colored layer is orange and the thickness is 1 μm to 3 μm,
Be careful of scratches. Thereafter, a metal thin film layer of aluminum was deposited by a batch-type wind-up deposition machine. At this time, the thickness of the metal thin film layer was 40 nm.

The resin film on which the metal thin film layer was formed via the transparent vapor-deposited layer was cut into an appropriate size, and a character-type protective layer was formed by printing at a desired position with a polyester ink. Alkali etching processing of the aluminum metal thin film layer was performed with an aqueous sodium hydroxide solution.
Then, the acid etching process of the transparent coloring layer was implemented with the heated sulfuric acid aqueous solution. After neutralization, sufficient washing and drying, a decorative layer was formed by printing with a polyester-based ink.

The resin film is deformed into a shape on the upper surface side of the resin button by a mold, and this resin film is inserted into an injection molding machine, and a polycarbonate resin which is a thermoplastic resin is injection-molded. Was integrated.
Finally, the outer periphery of the integrated sheet was cut out by punching, and a key sheet of a display portion having an orange mirror-like metallic luster in a punched character type was formed on the back surface of the resin film.

[0024]

Comparative Example 1 Comparative Example 1 will be described with reference to FIG. After completely removing dirt and foreign matter from the surface of the 50 μm-thick polyester film 1 formed into a sheet by the biaxial stretching method, a transparent blue colored coloring layer 5 of a character type was formed by printing with a polyester ink. At this time, the thickness is set to 2 ± 1 μm, and attention is paid to scratches. Then, the metal thin film layer 6 of aluminum was deposited by a batch type wind-up deposition machine.
At this time, the thickness of the metal thin film layer was 40 nm.

The resin film on which the transparent coloring layer and the metal thin film layer were formed was cut into an appropriate size, and a blank type protection layer 7 similar to the transparent coloring layer was formed by printing with a polyester ink (1). ). The aluminum metal thin film layer 6 was etched with an alkaline aqueous solution (2). The alkali etching process is based on a known method. After washing and drying are complete,
The decorative layer 8 was formed by printing with polycarbonate ink (3).

The resin film is deformed into a shape on the upper surface side of the resin button by a mold, and the resin film is inserted into an injection molding machine, and a polycarbonate resin which is a thermoplastic resin is injection-molded. Was integrated.
Finally, the outer periphery of the integrated key sheet was cut by punching, and a key sheet of a display portion exhibiting blue mirror-like metallic luster in the form of a cut letter was formed on the back surface of the resin film (4). However, as shown in FIG. 5, since the positions of the transparent coloring layer and the protective layer have shifted, the transparent coloring layer and the metal thin film layer have shifted, resulting in an undesired blank character type display portion.

[0027]

According to the key sheet of the present invention, the metal thin film layer is formed on the back surface of the resin film via the transparent coloring layer, so that a display portion having a rich color and a mirror-like metallic luster can be obtained. . In the manufacturing method of the present invention, only the metal thin film layer is colored by etching the transparent coloring layer, and the design can be expressed at a low price, thereby obtaining superiority in mass production. Further, by forming a transparent coloring layer made of a melamine-based ink and performing an etching process using a sulfuric acid etching solution, a key sheet having a color-rich, mirror-like metallic glossy display portion can be easily produced. .

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a key sheet of the present invention.

FIG. 2 is a manufacturing process of the key sheet of the present invention.

FIG. 3 is a longitudinal sectional view of a conventional key sheet.

FIG. 4 is a manufacturing process of a key sheet of a comparative example.

FIG. 5 is a top view of a key sheet of a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Resin film 2 Display part 4 Resin button 5 Transparent coloring layer 6 Metal thin film layer 7 Protective layer 8 Decorative layer

Claims (6)

[Claims] 1. A metal thin film layer is formed on a back surface of a resin film with a transparent coloring layer interposed therebetween.
A key sheet in which a resin film having a display portion on which a protective layer is laminated is integrated with an upper surface side of a resin button. 2. The key sheet according to claim 1, wherein the transparent coloring layer is made of a melamine-based ink. 3. A metal thin film layer is formed on one side of a resin film via a transparent coloring layer by dry plating, and a protective layer is formed on a desired position of the metal thin film layer by coating. Forming a display portion by removing the metal thin film layer and the transparent coloring layer, and then deforming the display portion of the resin film into the same shape as the upper surface side of the button so that the display portion is on the back side,
A method for manufacturing a key sheet, characterized in that a resin is filled in the deformation and a button is integrated. 4. The method according to claim 3, wherein the dry plating process is a vapor deposition process. 5. The transparent colored layer formed on one side of the resin film is a layer made of melamine-based ink, and the transparent colored layer is removed using an acidic etching solution as an etching solution. Or the method for manufacturing a key sheet according to 4. 6. The method according to claim 5, wherein the acidic etching solution is a sulfuric acid etching solution.