JP3506966B2 - Membrane switch sheet manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates are those concerning the manufacturing method of the sheet for membrane switches.

[0002]

2. Description of the Related Art As a membrane switch, which is one of thin switches used in electronic devices, etc., FIG.
There is a configuration shown in (b) (for example, Japanese Patent Laid-Open No. 4-2
15219). That is, the upper sheet 32a and the lower sheet 32b made of an insulating resin, in which the electrodes 31a and 31b are patterned by screen printing or the like, are attached to the insulating sheet 3.
3. The electrodes 3a and 3a of the insulating sheet 33
A hole 34 is formed at a position corresponding to 1b. Then, as shown in FIG. 4B, the holes 3 of the upper sheet 32a are formed.
When the position corresponding to 4 is pushed as indicated by the arrow, the upper sheet 32a is recessed and both electrodes 31a and 31b come into contact with each other to be in a conductive state, and the switch is held in a connected state. When the pressing is released, the upper sheet 32a returns to its original state due to its own rigidity, and the connection of the switch is released.

However, in the above configuration, the upper sheet 32
Since there is no click feeling when a is pressed with a finger, both electrodes 3
There is a drawback that it is not possible to intuitively confirm whether or not 1a and 31b are in contact with each other. In order to eliminate this drawback, as shown in FIG. 5, a large number of convex portions 3 are used instead of the flat upper sheet.
Insulating sheet 33 is an embossed sheet 35 made of polyester resin 5a (only one is shown) formed by embossing.
There is one that is sandwiched between (for example, JP-A-7-52).
No. 240). The electrode 31a is formed inside the convex portion 35a. Further, a flexible surface sheet 37 is arranged on the opposite side of the lower sheet 32b with the embossed sheet 35 interposed therebetween, with an insulating layer 36 interposed therebetween.

[0004]

[Patent Document 1] Japanese Patent Application Laid-Open No. 7-52240
In the case of the membrane switch disclosed in the publication, a click feeling is obtained, and it is possible to intuitively confirm whether the switch is on or off. However, since the pressing portion of the membrane switch is covered with the flat surface sheet 37, there is a possibility that a pressing error may occur during the blind touch operation. In addition, when the embossed sheet 35 is made of polyester resin (hard resin), the embossed sheet 35 has a problem that it is hard to touch and slippery when it is applied to a membrane switch in which the convex portion 35a is exposed on the surface without the surface sheet 37.

Further, in the case of the membrane switch disclosed in Japanese Patent Laid-Open No. 7-52240, it is necessary to form the electrode 31a inside the convex portion 35a, which complicates manufacturing. The present invention has been made in view of the above problems, and a first object of the present invention is to provide a bulging portion for obtaining a click feeling, suppress slippage of a surface, and prevent a switch from being pressed incorrectly. Manufacture of Membrane Switch Sheet
To provide a method . A second object of the present invention is to provide a membrane switch that uses the sheet and does not require electrodes to be formed on the membrane switch sheet and is easy to manufacture.

[0006]

To achieve the first object, according to an aspect of, the invention described in claim 1, in the laminated sheet as a rigid plastic layer and the soft layer firmly bond the crosslinked silicone rubber layer, A membrane formed by molding a bulge portion for switch click projecting to the side of the crosslinked silicone rubber layer .
In the manufacturing method of the switch seat, a hard plastic
After bonding the uncrosslinked silicone rubber layer to the layer,
Biaxially oriented polyethylene terephthalate / roll as film
Stretched polypropylene laminated film with the silicone
Crimped on rubber and heat in the crimped state by heating
Crosslinked and cured rubber, with a protective film
Then, the bulging part for the switch click by press working
And then peel off the protective film to remove the membrane.
It is used as a switch sheet .

According to a second aspect of the present invention, in the invention according to the first aspect, the silicone rubber produced by the heating is
Crosslinking and curing are carried out at a temperature of 150 ° C.
Be done. In the invention described in 請 Motomeko 3, producing side of the sheet membrane switch of the invention according to claim 1 or claim 2
In the method, the uncrosslinked silicone rubber is
And a polysiloxane containing two or more vinyl groups
Siloxane oligo having 3 or more SiH groups as a cross-linking agent
Comprising a mar .

Therefore, according to the first aspect of the invention, the swelling portion for switch click formed on the laminated sheet of the hard plastic layer and the soft layer is formed so as to project to the soft layer side. , When the finger touches the bulge, it feels soft and does not slip easily.

Further , since the soft layer is composed of a crosslinked silicone rubber layer, it has excellent heat resistance as compared with ordinary rubber, and less deterioration in elasticity when used at high temperatures.

[0010]

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below. First, the membrane switch sheet will be described. As shown in FIG. 1A, a membrane switch sheet 1 includes a laminated sheet 4 in which a hard plastic layer 2 and a soft layer 3 are firmly bonded to each other, and a plurality of switch click protrusions protruding toward the soft layer 3 side. It is formed by forming the projecting portion 5.

As shown in FIG. 1 (b), the laminated sheet 4 is formed in a rectangular shape, and the swelling portions 5 for switch click are arranged in a matrix at predetermined intervals. Bulge 5
Are formed to have substantially the same size as the holes provided at the positions corresponding to the electrodes of the membrane switch described later.

The hard plastic layer 2 is formed of a biaxially stretched polyethylene terephthalate film (hereinafter referred to as a biaxially stretched PET film). The soft layer 3 is formed by crosslinking a silicone rubber composition.

Next, a membrane switch using the membrane switch sheet 1 constructed as described above is shown in FIG.
Follow the instructions below. The membrane switch 6 includes a substrate (printed circuit board) 7 on which switch electrodes 7a are formed in a matrix, a spacer 8 made of an insulating material in which holes 8a are formed at positions corresponding to the electrodes 7a, and electrodes 7a. Then, the main body portion 10 is composed of the insulating sheet 9 in which the electrodes 9a constituting the switch are formed in a matrix.
The laminated sheet 4 is laminated on the main body 10 in a state where the swelling portion 5 for switch click corresponds to the hole 8a.

Next, a method of manufacturing the membrane switch sheet 1 and the membrane switch 6 configured as described above will be described. First, 2 with a predetermined thickness (for example, 12 μm)
An uncrosslinked silicone rubber composition is adhered to the base film made of an axially stretched PET film, if necessary after an adhesion treatment. The thickness of the silicone rubber composition is 3
0 μm to 1500 μm is preferable. As the adhesion processing,
For example, an undercoat layer is formed of a polyurethane resin or an amorphous polyester resin that can be applied to a film, and a thermosetting thin film layer containing a silicone resin having a high affinity for the undercoat layer is formed thereon. Examples of the silicone-based resin forming the thermosetting thin film layer include condensation type silicone resins.

As the uncrosslinked silicone rubber composition,
For example, an electron beam cross-linking type (electron beam curing type) silicone elastomer is used. As electron beam cross-linking type silicone elastomers, those mainly composed of vinyl group-containing polydimethylsiloxane are generally used. However, some of the methyl groups are substituted with phenyl groups or trifluoropropyl groups. Good.

Next, a protective film mat-coated on a biaxially stretched PET film having a thickness of 20 μ is pressure-bonded so that the mat-coat side faces the silicone rubber composition, and thereby 3
Form a layer stack. The matte coating is also called matte treatment and means forming fine irregularities on the surface of the film or applying a layer containing fine particles.

Next, by irradiating the above three-layer laminate with an electron beam, the intermediate layer silicone rubber composition is crosslinked to obtain a raw laminate sheet. Irradiation dose is 20 kGy-150
kGy is preferred.

Next, the above original fabric laminated sheet is pressed into a predetermined shape by a pressing machine, and as shown in FIG. 3, a molding laminated layer consisting of a base film 11, a soft intermediate layer 12 and a protective film 13 is formed. The sheet 14 is obtained. The matte coat layer is not shown. The base film 11 constitutes the hard plastic layer 2 of the membrane switch sheet 1, and the soft intermediate layer 12 constitutes the soft layer 3. If necessary, the molded laminated sheet 14 is punched into a predetermined contour shape according to the key arrangement of the desk calculator, and then the base film 11 side is bonded to the insulating sheet 9 of the main body 10 of the membrane switch 6.

Thereafter, the protective film 13 is peeled and removed to expose the surface of the crosslinked silicone rubber. As a result, the matte pattern of the matte coat of the protective film 13, that is, the fine concavo-convex pattern is transferred to the exposed surface of the silicone rubber, and the exposed surface (surface) of the soft layer 3 becomes the matte surface (the surface having fine concavo-convex).

In the membrane switch 6 configured as described above, when the switch click bulging portion 5 is pressed with a fingertip, the bulging portion 5 is dented and the insulating sheet 9 is bent toward the base 7 side. The electrode 9a formed on the insulating sheet 9
Is held in contact with the electrode 7a formed on the base 7, and the switch is turned on (on). Bulge 5
When the pressure is released, the rigid plastic layer 2 returns to its original state due to its rigidity, and the switch is turned off.

This embodiment has the following effects. (1) Laminated sheet 4 in which sheet 1 for membrane switch is firmly adhered to hard plastic layer 2 and soft layer 3
In addition, a bulging portion 5 for switch click projecting to the soft layer 3 side was formed. Therefore, as compared with the case where a hard plastic layer such as a PET film alone is formed,
When the finger touches the bulging portion 5, the touch is soft, the slippage of the surface is suppressed, and it is possible to prevent the switch from being pressed incorrectly.

(2) The soft layer 3 is made of crosslinked silicone rubber. Therefore, even if the membrane switch sheet 1 is stored or used at a high temperature for a long time, it is less likely to be deteriorated as compared with a normal rubber, and the durability at a relatively high temperature is improved.

(3) Since the silicone rubber is cross-linked by electron beam cross-linking, heat is not applied to the base film 11 to be the hard plastic layer 2, so that the hard plastic layer 2 is not deteriorated by overheating during cross-linking. .

(4) Sheet 1 for membrane switch
Is formed of a laminated sheet 4 of a hard plastic layer 2 and a crosslinked silicone rubber. Therefore, the silicone rubber layer has the effect of assisting the flexibility of the hard plastic layer 2, and compared with the case where the hard plastic layer such as the PET film alone is formed, repeated pressing and releasing of the bulging portion 5 are performed. As a result, the decrease in flexibility due to the decrease is reduced and the durability is improved.

(5) Base film 11, soft intermediate layer 1
The three-layer laminate of 2 and the protective film 13 is press-molded to produce a molded laminated sheet 14, and then the protective film 1
3 is peeled off to remove the hard plastic layer 2 and the soft layer 3
A two-layer laminated sheet 4 is obtained. Therefore, the soft layer 3 is not likely to be damaged during press molding, and the soft layer 3 can be protected by the protective film 13 until the membrane switch sheet 1 is assembled to the membrane switch 6.

(6) Fine irregularities are formed on the surface of the soft layer 3. Therefore, when pressing the bulging portion 5,
More slippery. (7) Since a film having a matte treatment on the soft layer 3 side is used as the protective film 13, peeling the protective film 13 transfers fine irregularities to the surface of the soft layer 3. Therefore, it is possible to easily form fine irregularities on the surface of the soft layer 3.

(8) The membrane switch 6 is formed by laminating the membrane switch sheet 1 having the bulging portion 5 for switch click on the surface of the main body portion 10 with the soft layer 3 on the front side. There is. Therefore, unlike a conventional membrane switch using an embossed sheet having a convex portion for obtaining a click feeling, it is not necessary to form an electrode on the membrane switch sheet 1, and the manufacturing is facilitated.

(9) By laminating the membrane switch sheet 1 on an existing membrane switch having a click-free structure (for example, the structure shown in FIG. 4A), the membrane switch has a click feeling. It can be easily converted into a switch.

The embodiment is not limited to the above, but may be embodied as follows, for example. The cross-linking of silicone rubber is not limited to electron beam cross-linking, and other methods may be used. For example, crosslinking is performed at a temperature of about 150 ° C. in an addition type system as a silicone elastomer. In the addition type, crosslinking is performed by a hydrosilylation reaction in which a Si H group is added to a carbon double bond. As the silicone elastomer, for example, a polysiloxane containing two or more vinyl groups is used as a base polymer, a siloxane oligomer having three or more Si H groups is used as a crosslinking agent, and a platinum compound is used as a catalyst. A stretched polypropylene film (OPP) is preferable as the protective film. However, since OPP alone causes shrinkage during crosslinking, a PET / OPP laminated film is used. OPPs with surface matte treatment are commercially available, so commercially available matte-treated OPPs
A biaxially stretched PET film is laminated on the laminated film to form a laminate film, which is used as a protective film. Then, the matte coat side is heat-cured in a state of being pressure-bonded so as to be the silicone rubber composition side. In this case, the electron beam irradiation device is not required to crosslink the silicone rubber.

As the protective film 13 for electron beam cross-linking of silicone rubber, a commercially available mat-treated OPP laminated with a biaxially stretched PET film may be used.

When forming the membrane switch sheet 1, instead of producing a molded laminated sheet 14 having the bulging portion 5 by press-molding a three-layer laminated body including the protective film 13, a hard plastic layer 2 and You may press-mold the two-layer laminated body which consists of the soft layer 3, and may form the laminated sheet 4 which has the bulging part 5. In this case, the surface of the soft layer 3 may be damaged depending on the pressing conditions, but the protective film 13 is not required, and the number of manufacturing steps can be reduced and the cost can be reduced.

When the protective film 13 is used, a protective film which is not matt coated may be used. In this case, it is not possible to transfer fine irregularities to the surface of the soft layer 3, but the bulging portion 5 protruding toward the soft layer 3 side has a pressing operation as compared with the bulging portion formed on the hard resin sheet. It is hard to slip and feels good.

It is also conceivable to mold the bulging portion 5 by pressing in the uncrosslinked state of the silicone rubber. However, since there is fluidity in the uncrosslinked state, even if the silicone rubber layer is molded in a three-layer state in which it is sandwiched between the protective layer (protective film 13) and the base film 11, the silicone rubber layer is formed by the molding pressure. It is not good because it causes fluidity in the inner part and creates an extremely thin part. It is also possible to partially crosslink the bulged portion 5 to such an extent that flow is unlikely to occur during the molding, and to completely crosslink after molding. In this case, the effect of assisting the flexibility of the hard plastic layer 2 by the silicone rubber layer is improved.

A material other than the crosslinked silicone rubber, for example, urethane rubber may be used as the soft layer 3. A material other than the PET film, for example, a polyethylene naphthalate film, a polyimide film, or a polycarbonate film may be used as the hard plastic layer 2. Alternatively, a laminated film of a crystalline polyester film and another film may be used.

The bulging portions 5 are not limited to those arranged in a matrix, and may be appropriately changed depending on the arrangement of the switches of the electric product used. The shape of the bulging portion 5 is not limited to the circular shape, but may be changed to an appropriate shape such as an elliptical shape, a triangular shape, or a quadrangular shape. Further, it is not necessary to form all the bulging portions 5 to have the same size, and bulging portions having different sizes may be mixed depending on the design and purpose.

When a membrane switch is manufactured using the membrane switch sheet 1, the membrane switch may be applied to a membrane switch having a structure in which an electrode is formed on the back surface of the hard plastic layer 2. Also in this case, slippage of the surface can be suppressed, and erroneous pressing of the switch can be prevented.

The technical idea (invention) other than the claims that can be understood from the embodiment will be described below together with the effect thereof. (1) in the invention described in claims 1 to 3, fine irregularities are formed on the surface of the silicone rubber layer. In this case, slippage is less likely to occur when the switch is operated.

[0039]

(3) After a soft layer is firmly bonded to a hard plastic layer to form a two-layer sheet, a protective film covering the soft layer is laminated so that it can be peeled off, and is softened by pressing with a protective film. A method for manufacturing a membrane switch sheet, comprising forming a swelling portion for switch click projecting to a layer side, and then peeling a protective film to obtain a membrane switch sheet. In this case, it is possible to prevent the soft layer from being damaged during pressing.

(4) In the invention of (3), the protective film is provided with a matte coat on the soft layer side. In this case, when the protective film is peeled and removed, fine irregularities are transferred to the surface of the soft layer, and it becomes easy to form fine irregularities on the surface of the soft layer.

(5) A membrane switch sheet in which a bulge portion for switch click is formed on a laminated sheet in which a hard plastic layer and a silicone rubber layer are firmly adhered to each other. In this case, the silicone rubber layer has the effect of assisting the flexibility of the hard plastic layer, and compared with the case of forming the hard plastic layer alone such as a PET film,
The decrease in flexibility due to repeated pressing and release of the bulging portion is reduced, and the durability is improved. Further, the bulging portion is not limited to be formed so as to project toward the silicone rubber layer side, and may be formed so as to project toward the hard plastic layer side, but it is preferably formed so as to project toward the silicone rubber layer side. Is preferred.

[0043]

As described in detail above, the first to third aspects of the invention are described.
According to the invention described in (1), compared to an embossed sheet having a click feeling formed only of hard plastic, it is possible to suppress surface slippage and prevent erroneous pressing of a switch.

According to the invention as set forth in claim 1 , even if the membrane switch sheet is stored or used at a high temperature for a long period of time, it is hard to be deteriorated, and the durability at a relatively high temperature is improved .

[Brief description of drawings]

1A is a partially enlarged schematic sectional view of a membrane switch sheet according to an embodiment, and FIG. 1B is a partially schematic perspective view.

FIG. 2 is a schematic partial cross-sectional view of a membrane switch according to an embodiment.

FIG. 3 is a partially enlarged schematic cross-sectional view of a molded laminated sheet.

4A is a partial cross-sectional view of a conventional membrane switch, and FIG. 4B is a partial cross-sectional view of a state in which the switch is pressed.

FIG. 5 is a partial cross-sectional view of another conventional membrane switch.

[Explanation of symbols]

1 ... Sheet for membrane switch, 2 ... Hard plastic layer, 3 ... Soft layer, 4 ... Laminated sheet, 5 ... Swelling portion, 6 ...
Membrane switch, 10 ... Main body.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 10-53659 (JP, A) Registered utility model 3040415 (JP, U) Utility model registration 2597582 (JP, Y2) Patent 3441684 (JP, B2) (58) ) Fields investigated (Int.Cl. ⁷ , DB name) H01H 11/00 H01H 13/00-13/76 B32B 1/00-35/00

Claims (3)

(57) [Claims] [Claim 1] as a hard plastic layer and the soft layer cross-linking
The laminated sheet with the silicone rubber layer firmly adhered to
Manufacture of a membrane switch sheet with a switch bulge protruding from the crosslinked silicone rubber layer
Method of joining uncrosslinked silicone rubber layer to hard plastic layer
Then, as a protective film, biaxially stretched polyethylene terephthalate
A stretched / stretched polypropylene laminated film
Crimping the cone rubber and heating it in the crimped state to crosslink and harden the silicone rubber.
The protective film and then press
Mold the bulge for click-click, and then peel off the protective film for membrane switch
A method for manufacturing a sheet for a membrane switch to be a sheet . 2. Crosslinking of the silicone rubber by the heating
Curing is performed by setting the temperature to 150 ° C.
The method for producing a membrane switch sheet according to claim 1, wherein: 3. The uncrosslinked silicone rubber is a base rubber.
Polysiloxane containing two or more vinyl groups as a limer and
And siloxane ori having 3 or more SiH groups as a cross-linking agent
The method for producing a sheet for a membrane switch according to claim 1 or 2, comprising a gommer .