JPH11329139A - Silicone rubber keypad and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a keypad having a design effect and automatic returning function of a button part with a simple structure by laying a painted film and a silicone rubber in non-adhered state. SOLUTION: A silicone rubber keypad comprises a silicone rubber 2 and a painted film having a pattern layer 5 laminated on the surface thereof. In the skirt part of the keypad for imparting click function to a key button, the painted film and the silicone rubber 2 are laid in non-adhered state. The painted film comprises a base sheet 4, and the pattern layer 5 and adhesive layer 6 formed thereon. The base sheet 4 consists of polycarbonate 25-200 μm thick and the like. The pattern layer 5 consists of a print layer of urethane resin or the like formed on the base sheet 4 or a metal thin film layer by vacuum evaporation or the like. The adhesive layer 6 consists of silicone oil or the like formed except the non-adhesive part. Since the painted film and the silicone rubber are in non-contact state, the click feeling of the key button is not impeded, and the cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicone rubber keypad having a simple structure and a button automatic return function, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Hitherto, a keypad made of a silicone rubber molded product obtained by compression-heating and curing a silicone rubber composition has been used for a communication terminal such as a mobile phone, a remote controller, and an input keyboard for a personal computer. . Silicone rubber is excellent in heat resistance and cold resistance, and by using its rubber elasticity, a thin skirt part is formed at the bottom of the key button to give a click feeling, so that input confirmation can be performed with a fingertip feeling. It is a suitable material for keypads because it is possible and has excellent functionality. But,
Keypads using silicone rubber are difficult to color as secondary processing, and conventionally only silicone inks could be used.

As a method of painting a silicone rubber, a screen printing method using a silicone ink is generally used. Further, there is a combined method of forming a design by removing an unnecessary portion of the ink film by a laser etching method after coating.

In the screen printing method, since the printability of silicone ink is poor, it is difficult to form fine characters and patterns, and the combined method is costly and not economical. Further, the silicone ink requires high-temperature heat treatment for drying, and when performing multi-color processing, heat treatment is performed for each color, so that the productivity is poor.

Further, in the case of the screen printing method, there is a problem that the design is limited because the design is printed after the silicone rubber is formed. In other words, when the pattern is formed by the screen printing method, when the surface of the button portion of the silicone rubber keypad, which is the printing surface, is a curved surface,
The design is limited because it is difficult to print.

Furthermore, silicone rubber has a problem in long-term reliability because of poor abrasion resistance and poor oil resistance.

Therefore, in order to solve these problems,
A method of coating a painting film on the surface of silicone rubber has been proposed.

[0008]

However, in this method, the painted film adheres to the skirt portion, so that the rubber elasticity of the skirt portion is hindered, and it becomes difficult to obtain a good click feeling. In addition, there has been a problem that the painted film adhered to the skirt part is physically fatigued in a long-term use, causing a change in input load, resulting in a lack of stability. Therefore, in this method, the skirt portion is not provided on the silicone rubber keypad, and the click function is performed by a separate part such as a metal dome, but this has been a factor of cost increase.

Accordingly, the present invention provides a silicone rubber keypad which solves the above-mentioned drawbacks, has a simple structure, has a beautiful design effect, and has an automatic return function of a button portion, and a method of manufacturing the same. The purpose is to do.

[0010]

SUMMARY OF THE INVENTION The silicone rubber keypad of the present invention and a method of manufacturing the same are constructed as follows to achieve the above object.

In other words, the silicone rubber keypad according to the present invention is characterized in that a skirt portion for providing a click function to a key button of a keypad having a design film having a design layer laminated on the surface of silicone rubber is provided. And the silicone rubber were in a non-adhered state.

In the above invention, the adhesive layer may be provided between the painted film and the silicone rubber except for the non-adhered portion.

In the above invention, an adhesive layer is provided at least between the painted film and the silicone rubber at the adhesive portion, and a non-adhesive layer is provided at the non-adhesive portion so as to contact the silicone rubber. May be configured.

Further, in the method of manufacturing a silicone rubber keypad according to the present invention, a painted film having a design layer and an adhesive layer formed in a portion other than a portion corresponding to a skirt portion is aligned with a molding die. The silicone rubber composition was filled with the uncured silicone rubber composition, and after the silicone rubber composition was cured, the molding die was opened to obtain a silicone rubber keypad in which the painting film was integrated.

[0015]

Embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing one embodiment of the silicone rubber keypad of the present invention. 2 to 3 are cross-sectional views showing an example of a painting film used in the method of manufacturing a silicone rubber keypad according to the present invention. FIG. 4-
FIG. 5 is a sectional view showing an embodiment of the steps of the method for manufacturing a silicone rubber keypad of the present invention. In the figure, 1 is a silicone rubber keypad, 2 is silicone rubber, 3 is a painting film, 4 is a base sheet, 5 is a design layer, 6 is an adhesive layer, 7
Denotes a non-adhesive layer, and 8 denotes a molding die.

The silicone rubber keypad 1 of the present invention
In a skirt portion for providing a click function to a key button of a keypad having a configuration in which the painting film 3 having the design layer 5 is laminated on the surface of the silicone rubber 2, the painting film 3 and the silicone rubber 2 are not adhered. It is configured to be in a state.

The drawing film 3 has a pattern layer 5 and an adhesive layer 6 formed on a base sheet 4.

The base sheet 4 may be transparent or translucent, or may be colored. Specifically, polyethylene terephthalate, polypropylene, polycarbonate, polybutylene terephthalate,
A sheet made of a resin such as vinyl chloride, polyethylene, polyamide, polyurethane, acrylic, polyester elastomer, or polyurethane elastomer may be used. In particular, it is preferable to use a thermoplastic elastomer sheet such as a polyester elastomer or a polyurethane elastomer because the silicone rubber keypad 1 can have cushioning properties. In particular, when the button height of the keypad is 1 mm or more, it is desirable to use a non-stretched or low-stretched base sheet.

The thickness of the base sheet 4 is preferably 25 to 200 μm, particularly preferably 75 to 150 μm. The thickness of the base sheet 4 is 25
If it is less than μm, it is difficult to print, it is easily broken due to lack of strength at the time of molding, and it is difficult to secure accuracy because the pattern is easily stretched and does not stretch uniformly at the time of molding. There's a problem. The thickness of the base sheet 4 is 200
If the thickness exceeds μm, there are problems such as lack of flexibility, liability to wrinkle, increase in weight when the button portion of the silicone rubber keypad 1 is pressed, and uneconomical problems.

The pattern layer 5 may be formed by printing a pattern on one or both of the front and back surfaces of the base sheet 4. In order to prevent the painting film 3 and the silicone rubber 2 from deforming when the silicone rubber keypad 1 is pressed, the design layer 5 is adhered to both of them. Need to be excellent. Also, the design layer 5
May have a concealed portion and a light-transmitting portion. By forming such a pattern layer 5, when a light source is arranged on the back surface, a translucent keypad configured to emit numbers and the like can be obtained.

The design layer 5 is usually formed as a printing layer. As the material of the printing layer, urethane resin, vinyl resin, polyamide resin, polyester resin, acrylic resin, polyurethane resin, polyvinyl acetal resin, polyester urethane resin, cellulose ester resin, alkyd resin, heat A colored ink containing a resin such as a plastic elastomer, preferably a resin capable of forming a flexible film as a binder and a pigment or dye of an appropriate color as a colorant may be used. Examples of the printing layer forming method include an offset printing method, a gravure printing method,
A normal printing method such as a screen printing method may be used. In particular, an offset printing method or a gravure printing method is suitable for performing multicolor printing and gradation expression. In the case of a single color, a coating method such as a gravure coating method, a roll coating method, and a comma coating method can be adopted. The printing layer may be provided entirely or partially depending on the design to be expressed.

The design layer 5 may be composed of a metal thin film layer or a combination of a printing layer and a metal thin film layer. The metal thin film layer is for expressing metallic luster as the design layer 5, and is formed by a vacuum deposition method, a sputtering method, an ion plating method, a plating method, or the like. Metals such as aluminum, nickel, gold, platinum, chromium, iron, copper, tin, indium, silver, titanium, lead, and zinc, and alloys or compounds thereof are used according to the metallic luster color to be expressed. As an example of forming a partial metal thin film layer, after forming a solvent-soluble resin layer in a portion that does not require a metal thin film layer, a metal thin film is entirely formed thereon, and solvent cleaning is performed. There is a method of removing an unnecessary metal thin film together with the solvent-soluble resin layer. The solvent often used in this case is water or an aqueous solution. As another example, there is a method in which a metal thin film is formed on the entire surface, a resist layer is formed on a portion where the metal thin film is to be left, and the resist layer is removed by etching with an acid or an alkali. .

The adhesive layer 6 is a layer for obtaining adhesion to a silicone rubber composition to be formed later. The adhesive layer 6
It is formed excluding at least the non-adhered portion (see FIG. 2). As the adhesive, a silane coupling agent, silicone oil, or the like is suitable, and these can be used alone or in combination of two or more. Further, those obtained by adding these to urethane resin or the like may be used as the adhesive. As a method for forming the adhesive layer 6, a coating method such as a gravure coating method, a roll coating method, a comma coating method, a gravure printing method,
There are printing methods such as a screen printing method.

As another method of forming the non-adhesive portion, the non-adhesive layer 7 may be partially formed on the adhesive layer 6 formed entirely (see FIG. 3). The non-adhesive layer 7 only needs to be one that does not adhere to the silicone rubber 2, and for example, an acrylic resin, a vinyl resin, a urethane resin, or the like can be used.

The skirt portion is for giving a click feeling to the keypad, and is provided at a place where the button portion and the keypad base portion are connected.
It is a thin part of ~ 0.3mm. Usually, it is provided on the entire circumference of the button part. It is preferable to provide the button at an angle of 30 to 60 ° so that the button can be pushed.

The shape of the back surface of the button portion may be either a flat plate or a shape having a plurality of independent protruding portions each having a downward convex shape at a position corresponding to the button portion. Further, both may be combined.
The shape of the button and the protrusion may be the same as the shape of the button and the protrusion of the conventional silicone rubber keypad 1.

As a method of filling the concave portion on the back surface of the button portion of the painting film 3 with the silicone rubber composition, there is an insert molding method. The insert molding method is a painting film 3
Is supplied into a molding die 8, and at the same time as the silicone rubber composition is molded, the painting film 3 is integrally attached to the silicone rubber composition. In the insert molding method, since the painting film 3 can be attached simultaneously with molding in the molding die 8, the manufacturing process can be greatly simplified. Also,
The painting film 3 is stretched by the injection pressure of the molten resin,
Since it follows the molding die 8, there is an advantage that the three-dimensional silicone rubber keypad 1 can be easily obtained.

First, the painting film 3 is fed into a molding die 8 composed of a cavity die and a core die. The single-piece painting film 3 (see FIG. 4) cut or preformed in a desired shape in advance may be fed one by one, or a necessary portion of the long painting film 3 may be sent intermittently. When a long picture film 3 is used, it is advisable to use a feeder (not shown) having a positioning mechanism so that the register between the design layer 5 of the picture film 3 and the molding die 8 coincides with each other. . Further, when the painting film 3 is intermittently fed, if the painting film 3 is fixed by the cavity mold and the core mold after the position of the painting film 3 is detected by the sensor, the painting film 3 is always fixed at the same position. This is convenient because no misalignment of the symbol layer 5 occurs. Here, the painted film 3 may be heated so that the painted film 3 can easily follow the molding die 8. In order to perform heating, an infrared heater, a nichrome heater, or the like is preferably disposed near the painted film 3.

As the molding die 8, an injection molding die,
It is preferable to use a mold for silicone rubber (a mold for liquid silicone rubber injection molding, a mold for Liquid Injection Molding (LIM), a mold for simultaneous transfer of molding, a mold for compression molding, and the like. In addition to metal, rubber or plastic may be used, a temperature control method using water or oil as a heat medium used in ordinary resin molding, a temperature control method using an electric cartridge heater, or a combination thereof. The temperature of the molding die 8 may be controlled by the temperature control method described in the above.
60 to 220 ° C, preferably 80 to 200 ° C for part or all of
It is better to keep it.

Next, a resin forming the button portion is formed on the back surface of the painting film 3 (see FIG. 5). At this time, the painting film 3 may be preformed (see FIG. 4). By performing the preforming, when the drawing ratio is high, it is possible to prevent the painting film 3 from being broken or the painting film 3 from being locally stretched when the silicone rubber composition is injected. Examples of the preforming method include vacuum forming, pressure forming, vacuum pressure forming, and press forming.

After the molding die 8 is closed, the uncured silicone rubber composition is injected and filled into the molding die 8 from a gate provided in the core die to form the button portion and at the same time as forming the button portion. Glue.

The silicone rubber composition is a composition mainly composed of a liquid polysiloxane having a reactive group, a cross-linking agent and / or a curing catalyst. The silicone rubber composition cures to a rubber-like elastic material when left or heated at room temperature. It is. Depending on the curing mechanism, addition reaction type, radical reaction type and condensation reaction type can be raised, but addition reaction type is excellent in terms of excellent injection moldability, fast curing speed by heating and excellent curing uniformity. Liquid silicone rubber compositions are preferred.

A radical reaction type silicone rubber composition using an organic peroxide may be used. It consists of a gel or liquid vinyl-containing polyorganosiloxane as a base polymer at room temperature, a catalytic amount of an organic peroxide, and, if necessary, an inorganic filler such as fumed silica or precipitated silica. A pigment; a heat-resistant agent and the like. As the organic peroxide to be used, one having a decomposition temperature in the range of 50 to 200 ° C., for example, 2,4 dichlorobenzoyl peroxide or 2,5 dimethyl 2,5 di-tert-butylperoxyhexane, etc. should be selected. Is preferred.

Further, a silicone rubber composition having self-adhesive properties may be used. In this case, it is necessary to form the non-adhesive layer 7 on the base sheet 4. Further, the injection device, the gate and the surface of the molding die 8 which are in contact with the silicone rubber composition are coated with a fluororesin, or porous nickel plating or chromium plating is subjected to composite plating in which the fluororesin is impregnated, or It is desirable to use a molding die 8 made of a fluororesin.

Even if the silicone rubber composition is transparent or translucent, the silicone rubber composition is obtained by dissolving and decomposing a colorant such as an organic dye or a processed pigment into the above silicone rubber composition and has light transmittance. It may be a colored one or a colored one without light transmittance.

To cure the silicone rubber composition,
The curing temperature is 60 to 220 ° C., preferably 80 to 200 ° C., and is preferably lower than the heat melting temperature of the base sheet 4. If it is lower than 60 ° C., it takes a long time to cure the silicone rubber composition, and if it exceeds 220 ° C., it causes scorch. If the temperature is raised to the heat melting temperature of the base sheet 4, the base sheet 4 is melted, which is not preferable. Note that if the heating is performed for a short time, the base sheet 4 will not be melted even if the temperature exceeds the heat melting temperature of the base sheet 4.

After cooling the molded product, the molding die 8 is opened, the molded product with the picture film 3 is taken out, and the insert molding is completed, whereby the silicone rubber keypad 1 can be obtained. When the long picture film 3 is used, since the picture film 3 is integrated with the silicone rubber keypad 1, trimming on the outer periphery of the silicone rubber keypad 1 is required before taking out from the molding die 8. It is.

[0039]

EXAMPLE A urethane film having a thickness of 100 μm was used as a base sheet, and a pattern layer was formed by a screen printing method using a coloring ink using a urethane resin as a binder.

On top of this, an adhesive layer was formed on a portion of the keypad other than the skirt portion by a screen printing method using an adhesive obtained by adding a silane coupling agent to a urethane resin to obtain a picture-coated film.

After forming the painting film into a keypad shape by press molding using a press mold, it is inserted into a LIM molding die, and liquid silicone is injected and molded.
A silicone rubber keypad having a pattern formed on the display surface of the convex button portion was obtained.

The silicone rubber keypad thus obtained had a sufficient automatic return function without using a metal dome or the like as a separate component, and had a button portion having an excellent click feeling.

[0043]

Since the present invention has the above-described structure, it has the following effects.

The silicone rubber keypad of the present invention comprises:
Since the painting film and the silicone rubber are in a non-adhered state in the skirt portion, the painting film does not hinder the clicking feeling at the time of button input. Therefore, cost can be reduced without using a separate component such as a metal dome. Further, since the painting film and the silicone rubber are in a non-adhered state in the skirt portion, the painting film does not physically fatigue.

Further, according to the method of manufacturing a silicone rubber keypad of the present invention, a painted film provided with an adhesive layer other than a portion corresponding to a skirt portion is formed by positioning, sandwiching, and clamping a molding die. The cavity is filled with silicone rubber and molded, and the silicone rubber and the painting film are integrated. Therefore, it is possible to easily obtain a silicone rubber keypad in which the painted film of the skirt and the silicone rubber are in a non-adhered state.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a silicone rubber keypad of the present invention.

FIG. 2 is a cross-sectional view showing one embodiment of a painting film used in the method of manufacturing a silicone rubber keypad of the present invention.

FIG. 3 is a sectional view showing another embodiment of a painting film used in the method of manufacturing a silicone rubber keypad of the present invention.

FIG. 4 is a sectional view showing one embodiment of the steps of the method for manufacturing a silicone rubber keypad of the present invention.

FIG. 5 is a sectional view showing one embodiment of the steps of the method for manufacturing a silicone rubber keypad of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silicone rubber keypad 2 Silicone rubber 3 Painting film 4 Base sheet 5 Pattern layer 6 Adhesive layer 7 Non-adhesive layer 8 Mold for molding

Claims (4)

[Claims] 1. A skirt portion for providing a click function to a key button of a keypad having a structure in which a painting film having a design layer is laminated on a surface of silicone rubber, wherein the painting film and the silicone rubber are in a non-adhered state. A silicone rubber keypad, characterized in that: 2. The silicone rubber keypad according to claim 1, wherein an adhesive layer is provided between the painting film and the silicone rubber except for a non-adhesive portion. 3. The method according to claim 1, wherein an adhesive layer is provided at least between the painting film and the silicone rubber at the adhesive portion, and a non-adhesive layer is provided at the non-adhesive portion so as to contact the silicone rubber. The silicone rubber keypad according to any one of the above. 4. An uncured silicone rubber composition in a cavity, wherein a painted film having a design layer and an adhesive layer formed in a portion other than a portion corresponding to a skirt portion is positioned and sandwiched in a molding die. A method for producing a silicone rubber keypad, characterized in that a molding die is opened after the silicone rubber composition is cured to obtain a silicone rubber keypad in which a painted film is integrated.