JPH0773777A - Push button member for illumination type keyboard switch and manufacture thereof and illumination type keyboard switch - Google Patents

Abstract

PURPOSE:To provide a push button member for illumination type keyboard switch, which has a high productivity, excellent feeling of switching operation, high durability of a variable-shape part and the excellent translucent characteristic, and to provide a manufacturing method thereof and an illumination type keyboard switch using it. CONSTITUTION:A push button member 10 is made of thermoplastic polyester elastomer composition, and a variable-shape part 12 is formed integrally so as to be extended outward from the peripheral edge of a part 11 to be pushed. Thickness of the variable- shape part 12 is set at 0.05mm-0.4mm, and a thin thickness part 14 at 0.5mm-3mm of thickness is formed in the part 11 to be pushed, and this thin thickness part 14 is formed so as to transmit the light. An illumination type keyboard switch has a board 20, the push button member 10, a contact member 15 provided in the bottom surface of the part 11 to be pushed, and a light emitting member 30 provided under the thin part 14 of the part 11 to be pushed. The manufacturing method thereof includes a process of injection molding using a mold, in which a pin gate is opened at a part of a cavity corresponding to the thin thickness part 14 of the part 11 to be pushed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a push button member for an illuminated keyboard switch, a method for manufacturing the push button member, and an illuminated keyboard switch using the push button member.

[0002]

2. Description of the Related Art As a keyboard switch used for audio equipment, video equipment, OA equipment, telephone equipment such as touch-tone phones and cordless phones, calculators, and other devices, a variable type having an elastic spring function on the outer peripheral edge of a pressed portion. There is known a push button member having an integral part.

In the above keyboard switch, a push button member made of a translucent silicone rubber material is used, and letters, numbers, and symbols are formed on the translucent pressed portion by a light shielding material or the like. An illuminated keyboard switch has been proposed in which a display portion for indicating such as is provided, and a light emitting member is provided below the pressed portion (Actual exploitation 64).
No. 35626, Japanese Utility Model Publication No. 3-110729).

[0004]

However, when a push button member is manufactured using a silicone rubber material, a vulcanization step is required during molding and deburring work is required after molding. Therefore, there is a drawback that productivity is generally low. Further, in the method by hot press molding, it is difficult to uniformly fill the material in the entire cavity, so that it is difficult to keep the performance of each deformable portion of the push button member constant.

As the silicone rubber material, a material having a small filler content is generally used.
The push button member made of such a material has a problem that the deformable portion has low durability and thus has a short service life.

In order to solve this problem, it is conceivable to use a silicone rubber material having a large filler content, but in this case, the obtained push button member is
The pressed portion has low translucency, and is eventually unsuitable as a push button member for an illuminated keyboard switch.

Further, when a keyboard switch is manufactured by using a push button member made of silicone rubber, it is difficult to manufacture it by an automatic assembling machine because the push button member itself is too flexible.

On the other hand, push button members other than those for illuminated keyboard switches are known which are formed by injection molding thermoplastic polyester elastomer. However, since such a push button member lacks flexibility of the material itself, the feeling of switching operation is insufficient.

Further, it has been difficult to manufacture a push button member for an illuminated keyboard switch, which is made of such a thermoplastic polyester elastomer, for the following reasons. When a push button member is manufactured by injection molding using a thermoplastic polyester elastomer, a mold in which a pin gate is arranged near the center of the molding surface in the space corresponding to the pressed portion of the push button member in the cavity is used. To be However, in such a mold, when the mold material is poured and cooled and solidified and then the mold is opened, the molded product is separated from the gate without damaging the pressed part, Only a push button member having a certain thickness of the pressing portion can be obtained. Such a push button member is not suitable as an illuminated keyboard switch because even if a thermoplastic polyester elastomer composition containing no pigment is used, the translucency of the pressed portion is insufficient. It is something.

The present invention has been made in view of the above circumstances, and has high productivity, excellent switching operation feeling, and high durability of the deformable portion, but also the pressed portion. It is an object of the present invention to provide a push button member for an illuminated keyboard switch having good translucency and an illuminated keyboard switch using the push button member for an illuminated keyboard switch.

Another object of the present invention is to advantageously manufacture a push-button member for an illuminated keyboard switch, which has a deformable portion having a small thickness and has good translucency in a pressed portion. To provide a way to do it.

[0012]

A push button member for an illuminated keyboard switch according to the present invention is obtained by molding a thermoplastic polyester elastomer composition, and has a wall thickness that extends outward from an outer peripheral edge of a pressed portion. A push button member having a small deformable portion integrally formed,
The deformable portion has a wall thickness of 0.05 mm to 0.4 mm, and the pressed portion has a thin wall portion having a wall thickness of 0.5 mm to 3 mm, and the thin wall portion is a light transmitting portion. It is characterized by

Further, in the push-button member for an illuminated keyboard switch of the present invention, the thermoplastic polyester elastomer composition comprises 50 to 98% by weight of the thermoplastic polyester elastomer, and a diene rubber and / or an acrylic rubber 2 to It is preferable that 0.01 to 2 parts by weight of polyorganosiloxane is contained in 100 parts by weight of a mixed component composed of 20% by weight and a plasticizer of 0 to 30% by weight.

The illuminated keyboard switch of the present invention comprises a substrate, a push button member for the illuminated keyboard switch, which is arranged on the substrate, and a bottom surface of a pressed portion of the illuminated keyboard switch push button member. It is characterized by comprising a contact member provided and a light emitting member provided below a thin portion of a pressed portion in the illuminated keyboard switch push button member.

In the illuminated keyboard switch of the present invention, a key top member made of transparent resin may be provided on the pressed portion of the illuminated keyboard switch push button member.

The method for manufacturing a push-button member for an illuminated keyboard switch according to the present invention includes a step of injection molding with a die having a pin gate opening at a portion of the cavity corresponding to the thin portion of the pressed portion. It is characterized by

[0017]

In the push button member of the present invention, since the material is made of the thermoplastic polyester elastomer composition, injection molding is possible, so that the productivity is high and the deformable portion is made of a specific material. In addition, since the wall thickness is within a specific range, the feeling of switching operation is excellent and the durability of the deformable portion is high. Further, since the pressed portion is provided with a thin portion having a specific thickness, the thin portion has a sufficiently high light-transmitting property. Therefore, using this push button member When configuring an illuminated keyboard switch, light from a light emitting member provided below the pressed portion of the push button member is reliably transmitted.

In the method for manufacturing a push button member for an illuminated keyboard switch according to the present invention, by using a mold provided with a pin gate opening to a portion corresponding to a thin portion of the pressed portion in the cavity, the inside of the cavity is used. Since the molding material is surely filled also in the portion corresponding to the deformable portion having a small thickness, the desired push button member faithfully conforming to the shape of the cavity can be obtained. In addition, by using a specific thermoplastic polyester elastomer composition as a molding material, when the mold is opened after the molding material is injected into the cavity and cooled and solidified, the thin portion of the pressed portion in the molded product The molded product can be separated from the gate without being damaged, and as a result, the push button member having the thin portion of the pressed portion can be advantageously manufactured. Furthermore, by using the specific thermoplastic polyester elastomer composition as a molding material, the composition has light dispersibility, so that the obtained push button member has unevenness in the thin portion of the pressed portion. Even if it has a gate trace, the light transmitted through the thin portion is excellent in uniformity.

[0019]

EXAMPLES Examples of the present invention will be described below. FIG. 1 is an explanatory sectional view showing an example of a push button member for an illuminated keyboard switch according to the present invention. The push button member 10 is formed by integrally pressing a pressed portion 11 on a supporting portion 13 via a deformable portion 12 having a spring function and having a small thickness. Part 1
A deformable portion 12 is formed so as to extend outward from the outer peripheral edge of 1 in the shape of a truncated cone, and a support portion 13 is formed so as to horizontally extend outward from the outer peripheral edge of the deformable portion 12. A thin portion 14 is provided in the central portion of the pressed portion 11 by forming a recess K that opens at the bottom surface thereof.

The thickness t ₁ of the deformable portion 12 is 0.05 mm
To 0.4 mm, preferably 0.1 mm to 0.2 m
m. When the thickness t ₁ of the deformable portion 12 is less than 0.05 mm, the bending fatigue resistance of the deformable portion 12 becomes small, and it is difficult to mold the push button member 10 itself. Become. When the thickness t ₁ of the deformable portion 12 exceeds 0.4 mm, the push button member 10 concerned.
Has a heavy switching operation feeling.

The thickness t ₂ of the thin portion 14 is 0.5 mm
It is set to 3 mm, which ensures the translucency of the pressed portion 11. The area of the thin portion 14 is preferably 1/5 to 1/10 of the area of the upper surface of the pressed portion 11. Thereby, the bottom surface portion of the pressed portion 11 having a sufficient area for forming the contact member is secured, the strength of the pressed portion 11 is secured, and the specific thermoplastic polyester elastomer composition described later is Since it has a good light-transmitting property and a light-scattering property, the light-transmitting property of the pressed portion 11 is secured by using this. When the thickness t ₂ of the thin portion 14 is less than 0.5 mm, the push button member 10 has a poor sense of switching operation because the thin portion 14 is deformed when the pressed portion 11 is pressed. . Thickness t ₂ of thin portion 14
Is more than 3 mm, the push button member 10
Has a low light transmittance in the thin portion 14, and is therefore unsuitable as a push button member for an illuminated keyboard switch.

The push button member for an illuminated keyboard switch of the present invention is obtained by molding a thermoplastic polyester elastomer composition. This thermoplastic polyester elastomer composition comprises a component (A) composed of a thermoplastic polyester elastomer, a component (B) composed of a diene rubber and / or an acrylic rubber, a component (C) composed of a plasticizer, and a polyorgano. It is preferable that the component (D) composed of siloxane is contained.

The thermoplastic polyester elastomer as the component (A) is a polyester block copolymer,
The polymer chain has a high melting point crystalline segment mainly composed of an aromatic polyester unit and a low melting point polymer segment mainly composed of an aliphatic polyether unit and / or an aliphatic polyester unit.

The aromatic polyester unit of the high melting point crystal segment, which is a hard segment, is formed from an acid component and a polyol component.

The acid component forming the aromatic polyester unit is preferably an aromatic dicarboxylic acid, and in particular,
It is preferably terephthalic acid and / or 2,6-naphthalenedicarboxylic acid. In addition to terephthalic acid and / or 2,6-naphthalenedicarboxylic acid, other aromatic dicarboxylic acids such as isophthalic acid, adipic acid, sebacic acid, cyclohexane-1,4
-A small amount of an aliphatic dicarboxylic acid such as dicarboxylic acid or dimer acid may be used in combination.

The polyol component forming the aromatic polyester unit is preferably a glycol having 2 to 12 carbon atoms, and examples thereof include ethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexanediol and decanediol. .

The lower limit of the melting point of the high melting point crystalline segment is not particularly limited, but in general, the homopolymer has a melting point of 150 ° C. or higher, preferably 170 ° C. or higher, more preferably 190 ° C. or higher.

The aliphatic polyether unit constituting the low melting point polymer segment which is a soft segment is formed of polyalkylene glycol, and specific examples thereof include polyethylene glycol, polypropylene glycol, polytetramethylene glycol and polyethylene. Examples thereof include glycol-polypropylene glycol block copolymers, and polytetramethylene glycol is particularly preferable. These polyalkylene glycols preferably have a carbon to oxygen ratio of 2 to 4.5, and these can be used alone or in combination of two or more.

The aliphatic polyester unit, which is another unit constituting the low melting point polymer segment, is mainly formed of an aliphatic dicarboxylic acid and a polyol.

Examples of the aliphatic dicarboxylic acid forming the aliphatic polyester unit include succinic acid, adipic acid,
Examples thereof include sebacic acid and decanedicarboxylic acid, and in addition to these aliphatic dicarboxylic acids, a small amount of aromatic dicarboxylic acid such as isophthalic acid may be used in combination.

The polyol component forming the aliphatic polyester unit is preferably a glycol component having 2 to 12 carbon atoms, and specific examples thereof include a polyol forming the aromatic polyester unit of the high melting point crystalline segment. Examples are the same as those exemplified as the components.

The aliphatic polyester unit is obtained by polycondensing the above-mentioned aliphatic dicarboxylic acid and a polyol component by a usual method, and may be a homopolyester or a copolyester, or may be a cyclic lactone. It may be a polylactone obtained by ring polymerization, for example, poly-ε-caprolactone.

The upper limit of the melting point of the low melting point polymer segment is not particularly limited, but in general, the melting point of the homopolymer is 130 ° C. or lower, preferably 100 ° C. or lower. The molecular weight of the low melting point polymer segment is usually 4
It is from 00 to 6000.

The composition ratio of the high melting point crystalline segment and the low melting point polymer segment in the thermoplastic polyester elastomer is preferably 95/5 to 5/95 by weight ratio, more preferably 70/30 to 30 /. 70.
As the thermoplastic polyester elastomer, one having a softening point of 100 ° C. or higher is preferable.

The polyester block copolymer particularly preferably used as the thermoplastic polyester elastomer has a high melting point crystalline segment of polytetramethylene terephthalate or polytrimethylene terephthalate-
The low-melting polymer segment is formed of 2,6-naphthalate, and the low-melting polymer segment is a polyether such as polytetramethylene glycol, polytetramethylene adipate, poly-
It is formed of polyester such as ε-caprolactone.

Further, as a part of the dicarboxylic acid or glycol, a polycarboxylic acid, a polyfunctional hydroxy compound, an oxy acid or the like may be copolymerized. When these polyfunctional components are copolymerized in the range of 3 mol% or less, they act effectively as a viscosity increasing component.
Examples of such a polyfunctional component include trimellitic acid, trimesic acid, pyromellitic acid, benzophenonetetracarboxylic acid, butanetetracarboxylic acid, glycerin, pentaerythritol, or esters thereof,
An acid anhydride etc. can be mentioned.

The thermoplastic polyester elastomer can be produced by a usual polymerization method. A preferable polymerization method is to heat an aromatic dicarboxylic acid or its alkyl ester and a low melting point segment-forming diol to about 150 to 260 ° C. in the presence of a catalyst to carry out an esterification reaction or a transesterification reaction, and then A method for obtaining a thermoplastic elastomer by carrying out a polycondensation reaction while removing excess low-molecular diol under vacuum, a high-melting point polyester segment-forming prepolymer and a low-melting point polymer segment-forming prepolymer prepared in advance, A method for obtaining a thermoplastic polyester elastomer by mixing a bifunctional chain extender that reacts with the terminal groups of the prepolymer of (1) and reacting the mixture, keeping the system in a high vacuum, and removing volatile components, and a high degree of polymerization. The high-melting point polyester and lactones are heated and mixed, and the lactone is subjected to ring-opening polymerization. A method of obtaining a thermoplastic polyester elastomers by ether exchange reaction.

The component (B) is a diene rubber and / or an acrylic rubber. Examples of the diene rubber include natural rubber, polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, chloroprene rubber, n-butyl acrylate-butadiene rubber, and n-butyl acrylate-acrylonitrile-butadiene rubber.

Examples of acrylic rubbers include acrylic ester rubbers and ethylene-acrylic ester copolymer rubbers. These acrylic rubbers include epoxy groups, active chlorine groups, carboxyl groups, etc., which form crosslinking points. It may be a copolymer of monomers having a reactive group.

Of these, preferred are acrylonitrile-butadiene rubber, n-butyl acrylate-butadiene rubber, n-butyl acrylate-acrylonitrile-butadiene rubber, and acrylic rubber, and particularly preferred are acrylonitrile-butadiene rubber. .

In the present invention, it is preferable to use a molding material in which the above-mentioned component (B) is dispersed and mixed in the thermoplastic polyester elastomer as the component (A). Further, the average particle size of the component (B) in the state of being dispersed and mixed in the thermoplastic polyester elastomer is preferably 50 μm or less, more preferably 1
It is 0 μm or less, particularly preferably 5 μm to 0.01 μm. Here, the average particle diameter is obtained by measuring the particle diameter of the component (B) in the thermoplastic polyester elastomer observed by an electron microscope, and 100 or more particles of the component (B) in a random visual field. Is the average value of the diameters measured for these particles. In addition, for non-spherical particles, the diameter of a circle having the same area as the cross-sectional area of the particle was regarded as the particle size and converted.

Examples of the plasticizer which is the component (C) include a process oil or a softening agent for mineral oil rubber called extension oil, dioctyl phthalate, dibutyl phthalate, diethyl phthalate, butyl benzyl phthalate, di-2-. Phthalates such as ethylhexyl phthalate, diisodecyl phthalate, diundecyl phthalate, diisononyl phthalate, tricresyl phosphate, triethyl phosphate, tributyl phosphate, tri-2-ethylhexyl phosphate,
Trimethyl phosphate, tributoxyethyl phosphate, tris-chloroethyl phosphate, tris-dichloropropyl phosphate, condensed phosphoric acid ester, triphenyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, 2-ethylhexyl diphenyl phosphate , Trilauryl phosphate, tricetyl phosphate, tristearyl phosphate, trioleyl phosphate and other phosphoric acid esters, trimellitic acid octyl ester, trimellitic acid isononyl ester, trimellitic acid isodecyl ester and other trimellitic acid esters, Dipentaerythritol esters, dioctyl adipate, dimethyl adipate, di-
2-ethylhexyl adipate, diisobutyl adipate, dibutyl adipate, diisodecyl adipate, dibutyl diglycol adipate, di-2-ethylhexyl azelate, dioticule azelate, dioctyl sebacate, di-2-ethylhexyl sebacate, methylacetyl ricinolate, etc. Fatty acid esters, pyromellitic acid esters such as octyl pyromellitic acid, epoxidized soybean oil, epoxidized linseed oil, epoxy plasticizers such as epoxidized fatty acid alkyl ester (eg epoxidized fatty acid octyl ester), adipic acid ether Examples include polyether plasticizers such as esters, polyether esters, and polyethers. These plasticizers can be used alone or in combination of two or more.

The plasticizer which is the component (C) is used for the purpose of improving the fluidity of the thermoplastic elastomer composition and lowering the hardness thereof. The component (A) is used depending on the purpose of use of the plasticizer. Those which act selectively on (B) components, or those which act on (A) components and (B)
Those that act on both components can be appropriately selected.

When a plasticizer is used, from the viewpoint of compatibility with other components, phthalates, phosphates, epoxy plasticizers, polyether plasticizers,
It is preferable to use trimellitic acid esters and the like, and it is particularly preferable to use phthalic acid esters, trimellitic acid esters and polyether plasticizers. By using such a plasticizer, it is possible to prevent bleeding from occurring in the obtained molded product.

The polyorganosiloxane as the component (D) has the effect of improving the releasability from the mold when the push button member is manufactured by injection molding.

Specific examples of the polyorganosiloxane include dimethylpolysiloxane, methylpolysiloxane,
Examples thereof include methylphenyl polysiloxane, methyl hydrogen polysiloxane, and those obtained by modifying a part of these polysiloxanes with an epoxy group or an amino group.
Among these, dimethylpolysiloxane is preferable, and particularly preferable is one having a viscosity of 1 at 25 ° C.
It is a silicone oil composed of 0 to 30000 cs dimethylpolysiloxane.

In the above, the ratio of the components (A), (B) and (C) used is as follows: (A) component: (B) component:
Component (C) is 50 to 98% by weight: 2 to 20% by weight: 0
30% by weight, preferably 60 to 95% by weight: 5
15% by weight: 0 to 25% by weight, more preferably 70 to
95% by weight: 5 to 10% by weight: 0 to 20% by weight.

When the ratio of the component (A) is less than 50% by weight, the composition has low processability, and the push button member obtained from the composition has low mechanical strength. Become. Further, the ratio of the component (A) is 95
When the content is more than 10% by weight, the composition has low flexibility, so that the push button member obtained from the composition has a heavy switching operation feeling.

When the proportion of the component (B) is less than 2% by weight, the composition has a low flexibility, so that the push button member has a heavy switching operation feeling.
Further, when the proportion of the component (B) exceeds 20% by weight, the composition has low processability, and
The push button member obtained from the composition has low mechanical strength.

When the ratio of the component (C) exceeds 30% by weight, the push button member obtained from the composition has
Bleed-out of the plasticizer occurs, which is not preferable in practice.

The proportion of the component (D) used is 0.01 to 2 parts by weight, preferably 0, based on 100 parts by weight of the mixed component of the components (A), (B) and (C). ．
The amount is 01 to 1 part by weight, more preferably 0.01 to 0.5 part by weight, and particularly preferably 0.01 to 0.2 part by weight.

The ratio of the component (D) is such that the components (A) and (B)
When the amount of the component and the component (C) is less than 0.01 parts by weight based on 100 parts by weight of the mixed component, the composition has low releasability as a molding material. , The deformable part with a small thickness is likely to be deformed. Further, if the proportion of the component (D) exceeds 2 parts by weight, the push button member obtained from the composition is liable to bleed out of the component (D), which is not preferable in practice.

In the above composition, if necessary, various additives such as known molding aids such as a crystal nucleating agent and a lubricant,
Well-known antioxidants, heat- and weather-resistant stabilizers such as ultraviolet absorbers, antistatic agents, release agents and the like can be added.

In manufacturing the push button member,
As a material to be supplied to an injection molding machine, it is preferable to use a material in which the above components are melt-kneaded by various extruders, Banbury mixers, kneaders, mixing rolls, and combinations thereof. In melt-kneading, the addition order of each component is not particularly limited, for example, all components can be kneaded at the same time, or after kneading any component, other components may be added and kneaded. it can.

As the component (D), for example, a method in which the components (A), (B) and (C) are melt-kneaded and mixed with a Henschel mixer, ribbon blender, tumbler, etc., (A) It can be added by a method of adding the components during or after the polymerization step. Alternatively, the master batch may be prepared by previously mixing the component (D) with the component (A) at a high concentration, and the master batch may be mixed so that the final ratio is obtained.

The composition obtained as described above preferably has a JIS A hardness of 55 to 90. When the JIS A hardness is less than 55, the push button member obtained from the composition has insufficient click feeling and has low responsiveness as a switch. JIS
When the A hardness exceeds 90, the push button member obtained from the composition has a large load necessary to press the push button member, and thus has low responsiveness as a switch.

The method for producing a push-button member for an illuminated keyboard switch according to the present invention is an injection molding method using the above thermoplastic polyester elastomer composition as a molding material. That is, in the injection molding machine, the molding material charged into the hopper is melted by rotating the screw to fill the tip portion of the cylinder, and then the screw is driven by a piston to melt the molding material into a mold. Injection injection into the cavity. Then, after the molding material in the cavity is cooled and solidified by this mold, the mold is opened and the molded product is taken out to obtain a push button member.

In the manufacturing method of the present invention, as the mold, a mold provided with a pin gate opening to a portion corresponding to the thin portion of the pressed portion in the cavity is used.

FIG. 2 is an explanatory view showing a part of the construction of an example of an injection molding die which can be used in the manufacturing method of the present invention. This injection molding die is configured as a three-piece die including a runner stripper plate 50, a fixed-side die plate 51, and a movable-side die plate 52.

Specifically, a fixed-side mold plate 51 is separably provided on the lower surface side of the runner stripper plate 50, and a movable-side mold plate 52 is arranged on the lower surface side of the fixed-side mold plate 51. A cavity 62 is formed by a space surrounded by the side mold plate 51 and the movable side mold plate, and a runner 60 is formed in the runner stripper plate 50 and the fixed side mold plate 51 in communication with a sprue (not shown), and further fixed. A gate 61 is formed on the side template 51 so as to communicate from the runner 60 to the cavity 62. Further, the movable side mold plate 52 is ejected at one end thereof to release the molded product from the ejector pin 5.
3 is provided.

The gate 61 is a pin gate, and is provided so as to open in the center of the end face of the columnar portion 54 corresponding to the recess K of the pressed portion 11 of the fixed-side template 51. When the target push button member has a plurality of pressed portions, the gate 61 is provided in each of the columnar portions corresponding to the recesses of the pressed portions. The opening diameter of the gate 61 is preferably 0.2 mm to 0.8 mm.

By using the mold having such a structure, when the molding material is injected and injected into the cavity 62 of the mold, molding is performed also in the portion corresponding to the deformable portion having a small thickness in the cavity 62. The reliable filling of the material results in the desired pushbutton member which closely follows the morphology of the cavity 62 with great precision.

Further, the above-mentioned specific thermoplastic polyester elastomer composition used as the molding material has the characteristics that the viscosity in the molten state is low and the tensile strength in the solidified state is high.
When the movable-side mold plate 52 is opened from the fixed-side mold plate 51 in a state of being cooled after being injected and injected into the mold 2, the molded product can be gated without damaging the thin-walled portion of the pressed portion of the molded product. As a result, the push button member having a thin portion in the pressed portion can be advantageously manufactured. Furthermore, since the specific thermoplastic polyester elastomer composition has a light-dispersing property, the obtained push button member may have an uneven gate mark in the thin portion of the pressed portion,
The light transmitted through the thin portion is excellent in uniformity.

FIG. 3 is an explanatory sectional view showing an example of the illuminated keyboard switch of the present invention. In this illuminated keyboard switch, the above-mentioned push button member 10 is arranged on the substrate 20 provided with the conductive member 21, and the cover member 40 is arranged on the push button member 10. Then, on the bottom surface of the pressed portion 11 of the push button member 10, a contact member 15 formed by printing, for example, conductive ink is provided at a position facing the conductive member 21, and the thin portion of the pressed portion 11 is provided. A light-emitting member 30 is arranged below the element 14. In addition, in the periphery of the light emitting member 30 on the substrate 20, a vent hole 22 is provided so as to penetrate the substrate 20 in order to release heat from the light emitting member 30.

On the upper surface of the pressed portion 11 of the push button member 10, a display portion (not shown) showing characters, numbers, symbols and the like is provided. As a method of forming such a display portion, a method of providing a light-shielding film having a light-transmitting portion having a form of a character to be displayed on the pressed portion 11 by pad printing, screen printing, etc. A method of baking and coating a light-shielding material in a state where characters and the like to be formed on the portion 11 are covered with a masking material, and then peeling off the masking material, and baking-coating the light-shielding material on the entire surface of the pressed portion 11. Then, a method of cutting and removing a portion such as a character with a laser can be mentioned.

As the light emitting member 30, a light emitting diode can be used. When using this light emitting diode, the temperature of the push button member 10 rises due to heat generation of the light emitting diode, but it is not preferable that this temperature be 100 ° C. or higher for a long time. From this point of view, it is preferable to use a small light emitting diode of a few mW class. Further, as shown in FIG. 3, by providing the ventilation hole 22, it is possible to suppress the temperature rise of the push button member 10 due to the heat generation of the light emitting diode.

In the illuminated keyboard switch of the present invention, as shown in FIG. 4, a key top member 16 made of transparent resin is provided on the pressed portion 11 of the push button member 10. Good.

Examples of the transparent resin material for forming the key top member 16 include transparent ABS resin, acrylic resin, polycarbonate resin, polystyrene resin and the like.

When such a key top member 16 is provided, a display portion showing characters, numbers, symbols, etc. is formed on the upper surface of the key top member 16. Examples of the method of forming the display portion include the same method as the method of forming the display portion on the upper surface of the pressed portion 11 described above.

The illuminated keyboard switch provided with the key top member 16 has a hard feel like resin or metal when the key is pressed. Further, since the display portion is formed on the upper surface of the key dop member 16, the display portion can be easily replaced.

Specific examples of the illuminated keyboard switch according to the present invention will be described below, but the present invention is not limited thereto.

<Example 1> 90 parts by weight of a thermoplastic polyester elastomer "PIBIFLEX 35M (manufactured by Enichem Polymeri)" and acrylonitrile butadiene rubber "JSR / N230S (manufactured by Nippon Synthetic Rubber Co., Ltd.)" 10
Parts by weight and polyorganosiloxane "Silicone oil SH (Toray Dow Corning Silicone)" 0.05
And 2 parts by weight with a Henschel mixer
With a screw extruder, the heating temperature was 200 ° C. and the screw rotation speed was 150 r.p.m. p. m. 20 parts by weight of a plasticizer "SANSOCIZER DUP (manufactured by Shin Nippon Science Co., Ltd.)" was added in the middle of the twin-screw extruder during the kneading, and a pelletized molding material made of a thermoplastic polyester elastomer composition was added. Was prepared. The JIS A hardness of this molding material was 86. The above-mentioned thermoplastic polyester elastomer "PIB
"IFLEX 35M" is a multi-block polymer in which hard segments of aromatic polyester (polybutylene terephthalate) and soft segments of polyether (polytetramethylene glycol) are alternately linked, and has a molecular weight of 100,000 to 150,000 and a softening point of It has a 175 ° C. and JIS A hardness of 93.

According to the structure shown in FIG. 2, using S55C type general metal steel, the thickness of the portion corresponding to the deformable portion in the cavity is 0.2 mm, the thickness of the portion corresponding to the thin portion is 1.5 mm, the thin portion The area corresponding to the area is 7m
A mold A having m ² and a pin gate diameter of 0.6 mm was produced.

After the above molding material is sufficiently dried, the molding temperature is 210 ° C. by an injection molding machine equipped with a mold A.
A push button member was manufactured by molding under the conditions of. In the above molding process, when the movable side mold plate is opened from the fixed side mold plate in a state where the molding material is cooled after being injected and injected into the cavity, the thin portion of the pressed portion in the molded product is damaged. The molded product was separated from the gate without any use, and the resulting push button member had a slight appearance of the gate on the lower surface of the thin portion of the pressed portion, and had a good appearance. Moreover, the defective rate was 0.1% or less.

Evaluation The following items were evaluated for the obtained push button members. [Translucency] The total light transmittance of the pressed portion of the push button member was measured by converting a sample obtained by hollowing out the thin portion of the pressed portion with a razor to 100%.

[Sensing of Switching Operation] The pressing load and click rate of the push button member were measured. Here, the pressing load and the click rate are measured as follows. Maximum load Press the pressed part of the push button member installed on the board,
The operating load measured when the bottom surface of the pressed portion contacts the substrate is called pressing load. In this embodiment, 2 mm / s
The pressing load when pressed at a speed of ec was obtained. Click rate When the pressed portion of the push button member is pressed, the relationship shown in FIG. 5 is obtained between the measured operating load and the stroke. In this figure, that CTR the ratio of the difference of the operation load P ₂ at the operating load P ₁ and a minimum peak for operating the load P ₁ at the maximum peak. That is,
The click rate α is α = (P ₁ −P ₂ ) / P ₁ × 100
(%) Is required. In this embodiment, 2 mm / s
The click rate when pressed at a speed of ec was obtained.

[Durability of Variable Shaped Portion] The push button member obtained in Example 1 was subjected to a keying test of the push button member using an ABS resin keying rod having an outer diameter of 5 mm. The number of times deformation and cracking of the sample occurred was determined. The results are shown in Table 1 above.

Comparative Example 1 A push button member was produced in the same manner except that EMMA resin “Acryft WH501 (manufactured by Sumitomo Chemical Co., Ltd.)” which was a copolymer of ethylene and methyl methacrylate was used as a molding material. did. E above
The MMA resin "Acryft WH501" has a content ratio of ethylene and methyl methacrylate of 80% by weight: 20% by weight, a melt flow rate according to JIS K6370-1981 of 70 g / 10 minutes, a JIS A hardness of 90, and a softening point of 101 ° C. belongs to. In the above molding process, when the movable side mold plate is opened from the fixed side mold plate in a state where the molding material is injected and injected into the cavity and then cooled, the molded product is not smoothly separated from the gate and is pressed. A defective product such as a large gate mark formed in the thin portion of the portion or a deformed thin portion of the pressed portion was generated, and the defective rate reached 50%.

A non-defective product was selected from the obtained push-button members, and the non-defective push-button member was evaluated in the same manner as in Example 1 in terms of translucency, switching operation feeling, and durability of the deformable portion. The results are shown in Table 1.

[0080]

[Table 1]

As is clear from Table 1, the push button member of the present invention is the push button member obtained in Example 1, which is excellent in switching operation feeling and has high durability of the deformable portion.
Moreover, the pressed portion has a high translucency. Also, when the pressing load was measured after 1 million keystrokes, 1
It was 30 g. In the keystroke test, by shifting the keystroke position from the center of the key, a keystroke test is also performed at a position where the peripheral part of the end surface of the keystick stick on the pressing side touches the thin portion of the pressed part of the pushbutton member. But 1
When the thin portion and the deformed portion of the pressed portion were observed after 10 million keystrokes, no deformation or crack was observed.

On the other hand, in the push button member obtained in Comparative Example 1, cracks were found in the deformed portion by 5000 keystrokes, and the pressing load at this time was 100 g, which was before the keystroke test. It decreased to 50% or less of the pressing load. Further, in the same manner as in Example 1, a keying test was conducted at a position where the peripheral portion of the end surface on the pressing side of the keying rod was in contact with the thin portion of the pressed portion of the push button member, but after 5000 times of keying, The thin part of the pressed part was destroyed.

Further, with respect to the push button member obtained in Example 1, red, green, and
An illuminated keyboard switch was made using a yellow 1 mw light emitting diode, and an illumination confirmation test was performed in a room equipped with a 32 W + 28 W fluorescent lamp.
It was possible to confirm the light emission even from a distant position. Further, when the light emitting member was turned on and the illuminated state was observed from above the pressed portion, non-uniformity of the brightness caused by the traces of the gate was not recognized.

Reference Example The pressing load and the click rate were measured for the remote control switch “Display TV remote control G0501 (manufactured by Sharp)” which is a keyboard switch made of silicone rubber. This remote control switch has 20 pressed parts per unit.
It measured about each to-be-pressed part of 0 sample.

As a result, as for the pressing load, the average of all the pressed portions was 95 g, the maximum value was 145 g, and the minimum value was 68 g. The difference between the maximum value and the minimum value of the pressing load of each remote control switch is 40 g on average, and the maximum is 65 g.
g, the minimum is 32 g, and there was a large variation in the pressing load of each pressed portion in one remote control switch. The click rate was 8% on average for all the pressed parts, which was extremely low.

[Comparative Manufacturing Example] As shown in FIG. 6, a protrusion is provided at the center of the molding surface corresponding to the bottom surface of the pressed portion of the fixed-side template 51, and a gate 61 is provided at the center of the protrusion. Except for the above, a mold B was prepared in the same manner as the mold A, and a push button member was manufactured in the same manner as in Example 1 except that this mold B was used. When observing the deformable portion of the obtained push button member, it was found that the deformable portion had a non-uniform thickness and that the thickness of the deformable portion was larger than the target thickness, especially in the portion near the gate position. Tended to be.
In addition, a large number of defective products with welds were generated in the portion of the bottom surface of the pressed portion far from the gate position, increasing the defective product generation rate. It was very difficult to reduce the defective product generation rate.

[Comparative Example 2] As shown in FIG. 7, a metal mold was used except that a recess was provided in the center of the columnar portion 54 of the fixed-side template 51, and a gate 61 was provided in the center of the bottom surface of this recess. A mold C was prepared in the same manner as A, and a push button member was manufactured in the same manner as in Example 1 except that this mold B was used. The push button member obtained by this mold C has a circular thick portion with a thickness of 1.5 mm and a diameter of 1.5 mm in the center of the pressed portion, and the area around the thick portion is Is 5
A thin portion of mm ² is formed. The obtained push button member had insufficient translucency in the pressed portion. An illuminated keyboard switch was constructed in the same manner as in Example 1 except that this push button member was used, the light emitting member was turned on, and the illuminated state was observed from above the pressed portion. The central part of the was dark, making it unsuitable as an illuminated keyboard switch.

Comparative Example 3 A push button member was manufactured in the same manner as in Comparative Example 1 except that the mold C was used. In the above molding process, the defective rate was about 0.1, which is the same as that in Example 1.
% Or less. The obtained push button member had insufficient translucency in the pressed portion, and was about half the translucency in the pressed portion of the push button member according to Comparative Example 1.

[0089]

The illuminated push-button member for a keyboard switch according to the present invention has high productivity, excellent switching operation feeling, and high durability of the deformable portion, while being sufficiently high in the pressed portion. Since it has a light-transmitting property, a long service life can be obtained, and moreover, light from the light-emitting member provided below the pressed portion is sufficiently transmitted, and characters, numbers, symbols, etc. can be displayed on the pressed portion. It is possible to obtain an illuminated keyboard switch that displays.

Further, according to the manufacturing method of the present invention, it is possible to advantageously manufacture the illuminated button switch pushbutton member having the thin portion in the pressed portion and the deformable portion having a small thickness.

[Brief description of drawings]

FIG. 1 is an explanatory sectional view showing an example of a push button member for an illuminated keyboard switch of the present invention.

FIG. 2 is an explanatory diagram showing a part of the configuration of an example of an injection molding die that can be used in the manufacturing method of the present invention.

FIG. 3 is an explanatory sectional view showing an example of an illuminated keyboard switch of the present invention.

FIG. 4 is an explanatory sectional view showing an example of an illuminated keyboard switch provided with a key dopp member.

FIG. 5 is a characteristic curve diagram showing a relationship between an operating load and a stroke when a pressed portion is pressed.

FIG. 6 is an explanatory view showing a part of the structure of a die used in a comparative manufacturing example, in which a gate is provided on a protrusion provided on a molding surface corresponding to the bottom surface of the pressed portion of the fixed-side template. .

FIG. 7 is an explanatory diagram showing a part of the configuration of a mold used in Comparative Examples 2 and 3 and having a gate provided on the bottom surface of a recess provided in the center of the columnar portion of the fixed-side template. .

[Explanation of symbols]

10 push button member 11 pressed portion 12 variable shape portion 13 support portion 14 thin portion K recess 15 contact member 16 key top member 20 substrate 21 conductive member 22 vent hole 30 light emitting member 40 cover member 50 runner stripper plate 51 fixed side type Plate 52 Movable Side Mold Plate 53 Ejector Pin 54 Columnar Part 60 Runner 61 Gate 62 Cavity

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C08L 33:00 83:04) (72) Inventor Shinichi Takayama 6-9-6 Ikegami, Ota-ku, Tokyo Birdy Products Limited Company

Claims (5)

[Claims] 1. A push button member obtained by molding a thermoplastic polyester elastomer composition, wherein a deformable portion having a small wall thickness is integrally formed so as to extend outward from an outer peripheral edge of a pressed portion. The deformable portion has a thickness of 0.05 mm to 0.4 mm, and the pressed portion has a thin portion having a thickness of 0.5 mm to 3 mm, and the thin portion serves as a light transmitting portion. A push button member for an illuminated keyboard switch, which is characterized in that 2. A thermoplastic polyester elastomer composition comprising 50 to 98% by weight of a thermoplastic polyester elastomer.
And diene rubber and / or acrylic rubber 2 to 2
To 100 parts by weight of a mixed component consisting of 0% by weight and a plasticizer of 0 to 30% by weight, polyorganosiloxane 0.0
The push button member for an illuminated keyboard switch according to claim 1, wherein the push button member comprises 1 to 2 parts by weight. 3. A substrate, a push button member for an illuminated keyboard switch according to claim 1, which is arranged on the substrate, and a pressed portion of the illuminated keyboard switch push button member. An illuminated keyboard switch comprising: a contact member provided on a bottom surface; and a light emitting member provided below a thin portion of a pressed portion of the illuminated keyboard switch push button member. 4. The illuminated keyboard switch according to claim 3, wherein a key top member made of transparent resin is provided on the pressed portion of the push button member. 5. The method for manufacturing a push-button member for an illuminated keyboard switch according to claim 1 or 2, wherein a pin gate opening to a portion corresponding to a thin portion of the pressed portion in the cavity is provided. A method for manufacturing a push-button member for an illuminated keyboard switch, comprising a step of injection molding with a mold.