JP2597582Y2 - Membrane switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application field] The present invention relates to a membrane switch having a soft touch and excellent scratch resistance.

[Conventional technology]

2. Description of the Related Art Conventionally, telephone dial buttons, calculators, word processors, input keyboards for personal computers, etc., and other various switches, etc., having contacts using key buttons by mechanical operation have been used. In recent years, these switches have been widely used as membrane switches instead of key-button switches.

Compared to keyboard switches, membrane switches can be operated by simply pressing the surface slightly.Since there is no mechanically movable part, the configuration is simple, and when there are many switch parts, one by one. Since there is no need to assemble the switch, mass production is possible, the manufacturing cost is low, and further, there are various advantages, such as hardly allowing dust to enter inside, and being able to be formed thinner.

The conventional structure of the above membrane switch is such that a conductive layer having a gap is provided on a base material, the surface is protected by a plastic sheet, and numbers, characters, symbols, etc. are further formed on the surface of the plastic film by key contacts. The printed layer is formed at a location corresponding to.

Conventionally, polyurethane or polyethylene terephthalate sheets have been used as plastic films for membrane switches.

[Problems to be solved by the invention]

However, since the surface of the plastic film used in the conventional membrane switch has low scratch resistance, the surface is easily scratched during use of the membrane switch, and the design is deteriorated, and characters and symbols printed on the surface are also used. There was a problem that it became difficult to see etc.

On the other hand, since the plastic film itself does not have a very soft feel, there is a problem that the touch given by the membrane switch to the hand when the switch is pressed becomes hard and gives an unfavorable impression to the user.

As a membrane switch having an improved scratch resistance, there is provided a protective layer made of a resin having a high surface hardness such as a thermosetting resin such as silicone or melamine or an ultraviolet curable resin on the surface of a plastic film. Are known.

However, the membrane switch in which the protective layer is formed using a thermosetting resin or an ultraviolet curable resin has been improved in abrasion resistance, but the protective layer provided on the surface of the plastic film usually uses a resin having a high hardness. Therefore, compared to the conventional petit sticky sheet without the protective layer alone, there was a problem that the feeling became harder and the soft feeling was lower than that without the protective layer. .

The present invention solves the above-mentioned disadvantages of the prior art, and aims to provide a membrane switch having excellent scratch resistance on the surface and a soft touch.

[Means for solving the problem]

The present invention provides (1) ionizing radiation containing a urethane acrylate oligomer and a tactile enhancer comprising a lubricant selected from the group consisting of silicone, fluorine and olefin on the outermost surface of a plastic film provided on the surface side. A membrane switch having a surface protective layer formed by curing a curable resin; (2) the membrane switch according to (1), wherein the surface of the surface protective layer has fine irregularities; and (3) a surface protective layer. And (4) the membrane switch according to any one of (1) to (3), wherein the plastic film is a polyester film. It is an abstract.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The drawings show one embodiment of the present invention. As shown in FIG. 1 and FIG. 2, the membrane switch 1 of the present invention is cured by ionizing radiation containing a urethane acrylate oligomer on the outermost surface of a plastic film 2 on the front side. It has a surface protective layer 3 formed by curing a conductive resin.

The above-mentioned membrane switch 1 has a contact portion 7 formed by an insulating material 6 between the conductive layers 5a and 5b, which are vertically spaced from each other on the surface of the base material 4, and the surface of the contact portion 7. And a printed layer 8 provided by printing a design or the like corresponding to the contact portion 7 on the surface of the plastic film 2. The membrane switch 1 of the present invention is a surface protective layer 3 obtained by curing an ionizing radiation-curable resin having a urethane acrylate oligomer.
By using, a surface having excellent scratch resistance and a soft feel can be obtained.

The urethane acrylate oligomer used for the surface protective layer 3 which is a feature of the present invention is an isocyanate compound having two or more isocyanate groups and a polyol having a weight average molecular weight of 200 to 3000 having 1 to 4 hydroxyl groups in the molecule. An acrylate compound having a radically polymerizable unsaturated group having a hydroxyl group at a terminal, in a solvent or without solvent, in the presence of a polymerization catalyst such as an amine or an organotin compound or a hydroquinone. It is a urethane acrylate having a urethane group and a radically polymerizable unsaturated group in the molecule obtained by the reaction.

The isocyanate compound constituting the urethane acrylate is an aliphatic or aromatic diisocyanate compound having two or more isocyanate groups in one molecule, such as isophorone diisocyanate and hexamethylene diisocyanate.

Examples of the polyol having a hydroxyl group in the molecule constituting urethane acrylate include an addition reaction product of a diol compound having an aromatic or spiro ring skeleton and a lactone compound or a derivative thereof or an epoxy compound, a polybasic acid such as phthalic acid, and ethylene. Condensation products with polyols such as glycols, and polyester diols such as ring-opened polyester compounds derived from cyclic ester compounds; polyether diols such as polytetramethylene ether glycol, polyethylene glycol, and polypropylene glycol; and polycarbonate diols. These are used alone or in combination of two or more. The weight average molecular weight of a polyol having 1 to 4 hydroxyl groups in one molecule is 200 to 3
000 is preferable in terms of wear resistance and hardness.
Is particularly preferred.

Examples of the acrylate compound having a hydroxyl group at the terminal and having a radical polymerizable unsaturated group include hydroxylated derivatives of (meth) acrylates such as hydroxyethyl acrylate and hydroxypropyl methacrylate, and epoxy acrylates.

The ionizing radiation-curable resin composition forming the surface protective layer 3 is mainly composed of the urethane acrylate oligomer described above. For example, the crosslinked structure and other oligomers such as epoxy acrylate, acrylic acid-modified alkyd, and acrylic-modified polyester can be used. For the purpose of adjusting the viscosity, a compound containing a reactive diluent such as neopentyl glycol diacrylate, pentaerythritol diacrylate, trimethylolpropane triacrylate, or trimethylolpropane trimethacrylate can be used.

In the present invention, an ultraviolet absorber or a light stabilizer may be added to the protective layer 3 in order to improve the weather resistance of the surface protective layer 3 made of a resin as described above and prevent deterioration due to light. The ultraviolet absorber is, for example, a benzotriazole-based compound such as 2- (2-hydroxy-5-methylphenyl) benzotriazole, and the light stabilizer is, for example, 2- (3,5).
-Di-t-butyl-4-hydroxybenzyl) -2'-
Bis (1,2,3,6-pentamethyl-4) n-butylmalonate
-Piperidyl) and the like, and these ultraviolet absorbers and light stabilizers are used in the resin composition 10
0 to 10 parts by weight can be added in an amount of about 0.01 to 10 parts by weight, particularly 0.1 to 2 parts by weight of an ultraviolet absorber,
It is more effective to use 4 parts by weight together.

The surface protective layer 3 is formed by adding a solvent or a reactive diluent to the above resin composition so as to have an appropriate viscosity as necessary, and then applying a conventionally known roll coating method, gravure coating method, fountain coating method, curtain, or the like. Coating on the surface of the plastic film using a coating method such as a coating method, and a thickness of 2
It is preferable to form it to about 150 μm.

It is preferable to use an electron beam or an ultraviolet ray as the ionizing radiation for curing the ionizing radiation-curable resin. In the case of electron beam, it was emitted from various electron beam accelerators such as Cockloft-Walton type, Bande graph type, Resonant transformer type, Insulated core transformer type, Linear type, Dynamitron type, High frequency type
Irradiation is performed using an electron beam having an energy in the range of 100 to 300 KeV, preferably 150 to 200 KeV, so as to have a dose of 0.5 to 10 Mrad. In the case of ultraviolet rays, ultraviolet rays emitted from a light source such as a high-pressure mercury lamp, a low-pressure mercury lamp, a carbon arc, a xenon arc, and a metal halide lamp can be used.

In order to prevent the above-mentioned compound from being cured before irradiation of ultraviolet rays or electron beams, it is preferable to add hydroquinone, hydroquinone monomethyl ether, benzoquinone and the like to the above composition as a polymerization inhibitor. Further, in order to make the coating composition an ultraviolet curable resin, acetophenones, benzophenones, Michler benzoyl benzoate, α-amyloxyester, tetramethylthiuram monosulfide, thioxanthone are used as photopolymerization initiators therein. And n-butylamine as a photosensitizer,
Triethylamine, tri-n-butylphosphine and the like may be mixed.

In the surface protection layer 3 of the membrane switch 1 of the present invention, the urethane acrylate becomes a soft segment and the monomer functions as a hard segment. By adjusting the number of functional groups of the urethane acrylate, the molecular weight of the diol, and the amount of the monomer mixed, the surface protection layer 3 is formed. Physical properties such as flexibility of 3 can be adjusted.

A preferred ionizing radiation-curable resin forming the surface protective layer 3 is a composition containing one or more urethane acrylates having an average molecular weight of 500 to 50,000 and one or more radically polymerizable unsaturated groups per molecule. And those obtained by curing a composition comprising one or more acrylic monomers having the following formula:

Further, in the present invention, a soft feeling on the surface can be obtained only with the ionizing radiation-curable resin, but a touch improving agent is added to the surface protective layer 3 in order to further improve the touch on the surface. The tactile sensation improver is used to improve the tactile sensation of the coating film surface, and a lubricant selected from silicone, fluorine, and olefin is used. The surface protective layer 7 is formed by using a composition obtained by adding 0.05 to 15 parts by weight of one or more tactile sensation enhancers to 100 parts by weight of the ionizing radiation-curable resin, so that the cured The surface of the protective layer has sliminess (humidity) and softness is further improved.

The most preferable ionizing radiation-curable resin composition for forming the surface protective layer 3 is a compound having two or more isocyanate groups, a compound having 1 to 4 hydroxyl groups and 1 to 5 radical polymerizable unsaturated groups. Molecular weight of 500
A composition containing one or more urethane acrylates of up to 500,000, and a resin component comprising one or more acrylate monomers having one or more radically polymerizable unsaturated groups in one molecule; It comprises one or more tactile sensation enhancers in an amount of 0.05 to 15 parts by weight per 100 parts by weight of the resin component.

The material of the plastic film 2 provided on the surface side of the membrane switch 1 is polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyethylene terephthalate, polycarbonate, nylon, polystyrene, ethylene-vinyl acetate copolymer, ethylene- Plastics such as vinyl alcohol copolymers, ionomers, and cellulose triacetate, and natural or synthetic rubbers can be used.

The plastic film 2 has transparency, film rigidity,
From the viewpoint of material cost and the like, polyester films, polyvinyl chloride films, and polycarbonate films are preferred. More preferably, it is a polyethylene terephthalate film. The thickness of the plastic film 2 is 25-50
The thickness may be in the range of 0 μm, and preferably 50 to 250 μm.

In the present invention, the surface of the surface protective layer 3 can be formed into a mat by forming fine irregularities on the surface. For example, a method of adding a matting agent to the ionizing radiation-curable resin, and a method of ionizing the mat film can be used. There is a method in which the resin is brought into contact with the surface side of the radiation-curable resin in an uncured state and then irradiated with ionizing radiation to transfer fine irregularities of the mat film. Examples of the above matte film include a method of kneading and mixing a thermoplastic resin hematizing agent to form a film, and a method of obtaining a release film, a method of performing sandblasting or chemical etching on the surface of the release film, and the like. Further, it can be obtained by a method of applying a resin containing a matting agent to the surface of a release film. As a film having such a matte surface, a composition obtained by adding an isocyanate curing agent and a calcium carbonate, alumina, silica as a matting agent to a mixed resin of an acrylic polyol and a cellulosic resin and a silicone as a releasing agent is a thermoplastic resin. A film having a mat layer with a thickness of about 1 to 20 μm can be used by coating and curing the film surface. Further, if the fine irregularities are printed in a pattern, a matte portion and a glossy portion can be formed in a pattern on the surface of the release layer after the transfer.

Although not particularly shown in the present invention, the plastic film 2
A primer layer 3 can be provided between the substrate and the surface protective layer 3. The primer layer is used for the purpose of further improving the adhesion between the plastic film 2 and the surface protective layer 3, and is, for example, a vinyl chloride-vinyl acetate resin (for example, a single substance such as VYCH, VYHH, VYGH or a mixture thereof), an acrylic resin, urethane Active isocyanates such as resin and tolylene diisocyanate are used.

In the production of the membrane switch of the present invention, the ionizing radiation-curable resin containing the urethane acrylate oligomer is cured on the outermost surface side of the conventionally known membrane switch having a plastic film to form the surface protective layer 3.
To form a membrane switch of the present invention,
In addition, if necessary, a printed layer, a primer layer, etc. are provided on the surface of the plastic film, and then an ionizing radiation-curable resin is applied and cured to form a surface protective layer, which is previously manufactured. A method of assembling a membrane switch or the like can be used.

Next, the present invention will be described in more detail with reference to specific examples.

Example 1 100 parts by weight of urethane acrylate (manufactured by Nippon Gohsei) and 2-ethylhexyl ether acrylate (manufactured by Toa Gosei Kogyo Co., Ltd.) were placed on the surface of a membrane switch having a polyester film (manufactured by Teijin) having a thickness of 125 μm as a plastic film on the front side. Apply 50 parts by weight of ionizing radiation-curable resin composition, and irradiate the above coating with an electron beam with an accelerating voltage of 5 Mrad using a scanning type electron beam irradiation machine to protect the surface with a thickness of 20 μm. A layer was formed.

The resulting membrane switch had excellent surface scratch resistance and had a soft touch.

Example 2 100 parts by weight of urethane acrylate (manufactured by Nippon Gosei Kagaku), 2-ethylhexyl acrylate (manufactured by Toa Gosei Co., Ltd.) 20 were placed on the surface of a membrane switch having a polyester film (manufactured by Teijin) having a thickness of 100 μm as a plastic film on the front side. Parts by weight and 30 parts by weight of neopentyl glycol dimethacrylate (manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd.), and a mat-like polyester film (manufactured by Toray: X-43) is applied to the coated surface. After lamination, the mat film was irradiated with an electron beam from the mat film side and cured, and then the mat film was peeled off to form a surface protective layer having a thickness of 20 μm.

The resulting membrane switch has excellent surface scratch resistance and softness, and has a surface gloss value (60 ° specular gloss) of 42%.
And had a good matte appearance.

Example 3 100 parts by weight of urethane acrylate (manufactured by Nippon Synthetic Chemical) and 2-ethylhexyl ether acrylate (manufactured by Toa Gosei Co., Ltd.) were placed on the surface of a membrane switch having a polyester film (manufactured by Teijin) having a thickness of 125 μm as a plastic film on the front side. 20 parts by weight, 30 parts by weight of neopentyl glycol dimethacrylate (manufactured by Kyoeisha Yushi Kagaku Kogyo), photoinitiator (manufactured by Ciba Geigy: Irgacure 65)
1) A composition comprising 5 parts by weight and 30 parts by weight of methyl ethyl ketone was applied by gravure coating and dried at 100 ° C. for 2 minutes with hot air. Next, a mat-like polyester film (manufactured by Toray Industries, Inc .: X-43) was laminated on the coated surface, and ultraviolet rays were irradiated from the matte film side (using a high-pressure mercury lamp of 160 w / cm and passing under it at 5 m / min). After curing, the mat film was peeled off to form a surface protective layer having a thickness of 20 μm.

The resulting membrane switch had excellent surface scratch resistance, had a soft touch, and had a matte appearance with a surface gloss value (60 ° specular gloss) of 42%.

Example 4 In Example 2, 2 parts by weight of a fluororesin-based lubricant and silica 5 were used as a tactile sensation improver in the ionizing radiation-curable resin composition.
Example 2 was used by adding a part by weight.
A surface protection layer was formed in exactly the same manner as described above to obtain a membrane switch.

The obtained membrane switch is excellent in scratch resistance and soft feeling as in Example 2, has a surface gloss value (60 ° specular gloss) of 42%, and has a good matte appearance. It has a surface feel that balances moderate slipperiness and adhesiveness, holds the fingertip pressing the membrane switch without slipping, and when the finger is released, the finger is not pulled on the membrane surface and the switch operability is improved. It was good.

[Effect of the invention]

As explained above, the membrane switch of the present invention is
Since the plastic film has a surface protective layer formed by curing an ionizing radiation-curable resin containing urethane acrylate oligomer on the surface, the conventional plastic film alone without a protective layer or a thermosetting resin or an ultraviolet-curable resin Compared to those using a protective layer such as a resin, it has a surface with excellent scratch resistance and can provide a soft touch. In addition, by adding a tactile sensation improver to the surface protective layer, the surface protective layer after curing can form a wet surface having a slimy property and an excellent feel, resulting in good softness.

Furthermore, by providing fine irregularities on the surface of the surface protection layer, the surface of the membrane switch is formed in a matte state, and as a result, it has an antireflection effect. This has the effect that the design is easy to see. In addition, the fine irregularities also have a slip prevention effect, and the switch can be pressed reliably.

The membrane switch of the present invention provides a primer layer between the surface protective layer and the plastic film,
In the membrane switch of the present invention, the adhesion between the surface protective layer and the plastic film is improved, and the surface protective layer is securely adhered to the plastic film. There is no.

In addition, by using a polyester film as the plastic film, the polyester film is excellent in raw material cost, physical properties, and the like, so that the workability, cost, and the like of membrane switch production can be reduced.

[Brief description of the drawings]

The drawings show an embodiment of the present invention, FIG. 1 is a perspective view of the membrane switch of the present invention, and FIG. 2 is II-II in FIG.
It is a line longitudinal cross-sectional view. 1 ... Membrane switch, 2 ... Plastic film, 3 ... Surface protective layer

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-176614 (JP, A) JP-A-1-244848 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01H 13/00-13/76 H01H 11/00-11/06 B32B 1/00-35/00

Claims (4)

(57) [Scope of request for utility model registration] 1. An ionizing radiation curing method comprising a urethane acrylate oligomer and a tactile enhancer comprising a lubricant selected from the group consisting of silicone, fluorine and olefin at the outermost surface of a plastic film provided on the surface side. Membrane switch having a surface protective layer formed by curing a conductive resin 2. The membrane switch according to claim 1, wherein the surface of the surface protective layer has fine irregularities. 3. The membrane switch according to claim 1, further comprising a primer layer between the surface protective layer and the plastic film. 4. The membrane switch according to claim 1, wherein the plastic film is a polyester film.