JPS60235317A - Pushbutton switch member - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a push-button switch member, and particularly to a push-button switch member in which a key top portion having excellent strength and wear resistance is integrally molded with a dome-shaped elastic body portion.

Rubber pushbutton switch members are commonly used as keyboard components for input devices of various electrical and electronic devices such as desktop computers, computers, telephones, and typewriters, but these have conductive rubber contacts. Since the dome-shaped elastic body portion and the key top portion are integrally molded from the same rubber material, it is advantageous in that costs can be reduced by reducing the number of parts of the keyboard and streamlining the assembly process. These rubber pushbutton switches are often made of silicone rubber, which has excellent electrical properties.

Since this dome-shaped elastic body part and the key top are integrally molded, the key top part is usually made of silicone rubber, but since silicone rubber is easily charged with static electricity, there is a risk of foreign matter adhering to the key top. However, since the silicone rubber is used in comparison terms and conditions, there may be problems with the feel of keys that are pressed many times), and what's more, the silicone-based ink characters printed on the key tops during use. The disadvantage is that the symbol disappears due to kite wear.

Therefore, it has been proposed to make this key top part from other plastic materials with high hardness, but if it is made of dome-shaped elastic material or silicone rubber, it is difficult for the silicone rubber to adhere to other plastic materials. and
In that case, it is necessary to apply a primer composition consisting of various silane compounds, which complicates the assembly process.
The disadvantage is that it is not economical.

The present invention relates to a push-button switch part that solves these disadvantages.The key top part is molded from a thermosetting silicone-modified epoxy resin, a liquid silicone rubber composition is applied to this surface, and then thermosetting is performed. This is characterized in that the push button switch member is integrally formed by placing silicone rubber thereon and heating and pressurizing it.

In other words, the present inventors have conducted various studies on methods for obtaining an integrally molded push button switch whose dome-shaped elastic body is made of silicone rubber, which has a key top section with high hardness, strength, and abrasion resistance. , when this key top part is especially molded with a silicone-modified epoxy resin, this molded body will be completely adhered to the liquid silicone rubber composition without the use of a primer composition, and the cured film of this liquid silicone rubber will naturally have a dome shape. Since it is completely bonded to the thermosetting silicone rubber that makes up the elastic body, it is said that if these materials are molded according to conventional methods, it is possible to easily obtain an integrally molded push button switch member. Since the key top part of this key is mainly made of epoxy resin, which has a hardness of 1 strength and excellent wear resistance, there is no risk of foreign matter adhering to it.

The present invention was completed by confirming that the surface display does not disappear and the touch feel is also excellent. The f-type epoxy resin is composed of an epoxy resin, its curing agent, and organopolysiloxane, and any of these may be known. Therefore, this epoxy resin has a small number of epoxy bonds (at least 2
There is no particular restriction on the molecular structure and molecular weight as long as the compound has 2,2'-bis(4-hydroxyphenyl)propane or its chloride diglycidyl ether-butadiene dieboxide, Vinylcyclohexene dioxide, diglycidyl ether of resorcinol, 1,4-bis(2,3-epoxypropoxy)benzene, 4,4'-bis(2,3-epoxypropoxy)diphenyl ether, 1,4-bis(2) ，
3-epoxypropoxy)cyclohexene-bis(3,
Epoxyglycidyl ether or polyglycidyl ester obtained by combining epichlorohydrin with 4-epoxy-6-methylcyclohexylmethyl), 'l,2-dioxybenzene or resorcinol-polyhydric phenol or polyhydric alcohol. .

Examples include epoxy novolac obtained by condensing a novolac type phenolic resin (or 10-genated novolac type phenolic resin) and epichlorohydrin, epoxidized polyolefins obtained by 1) epoxidation by a peroxidation method, and epoxidized polyfridiene. However, they may also be used in combination with monoepoxy compounds such as styrene oxide, cyclohexene oxide, propylene oxide, methyl glycidyl ether, ethyl glycidyl ether, phenyl glycidyl ether, allyl glycidyl ether-octylene oxide dodecene oxide, and the like.

Furthermore, various conventionally known curing agents can be used.

Amine compounds such as diethylenetriamine, triethylenetetramine-diethylaminoprobylamine, N-aminoethylpiperazine I, modified aliphatic polyamines such as epoxy resin-diethylenetriamine adduct, amine-ethylene oxide adduct-cyanoethylated polyamine, bisphenol A-) Methylolallyloxyphenol, phenolic novolak resin with low degree of polymerization, epoxidized or butylated phenolic resin, urea resin, melamine resin, amine resin such as aniline resin, polysulfide resin, heptalic anhydride, hexahydrophthalic anhydride, tetrahydrocarbon Examples include organic acids or their anhydrides such as heptatalic anhydride-pyromellitic anhydride, methylnadic anhydride, dodecylsuccinic anhydride, and chlorendic anhydride.

This is 11 to 100 parts by weight of the above-mentioned epoxy resin.
It may be added in an amount of 200 parts by weight, preferably 5 to 100 parts by weight.

In addition, the silicone added to this epoxy resin has hydrogen atoms bonded to silicon atoms in its molecules.

It is necessary to use an organosilane or organosiloxane having at least two hydroxyl groups or hydrolyzable groups. , a is 1 or 2), but this organosiloxane may also contain an epoxy group (and this organosiloxane may contain R, Si Oo,, units). Although the main skeleton may be a copolymer with 8102 units, it is preferable that the average degree of polymerization of this organosiloxane is 100 or less from the viewpoint of dispersion and compatibility in the epoxy resin. If the amount of this silicone compound added to the epoxy resin is too small, the adhesion between this composition and the liquid silicone rubber described later will be insufficient, and if it is too large, the mechanical strength of the cured resin will decrease. 0.5 for 100 stacked parts
~10 parts by weight, which also improves compatibility with the epoxy resin,
It may be added after being modified with alkyd resin, acrylic acid, ester resin, etc.

This silicone-modified epoxy resin can be obtained by uniformly kneading the above-mentioned epoxy resin, curing agent, and organosilane or organopolysiloxane using a mixing device such as a heating roll or a heating kneader. The resin may be copolymerized with organosilane or organosiloxane in advance.

Also.

This silicone-modified epoxy resin contains a known inorganic filler and a catalyst for curing the epoxy resin. The composition may be colored by adding additives, pigments, etc., or it may be made conductive by adding carbon black, metal powder, metal oxide, etc., but this does not make the composition after kneading o. It is preferable to use it as a powder that has been ground to about oi to 5u.

The liquid silicone rubber composition used for this purpose may be either an addition reaction type or an organic peroxide vulcanization type as long as it is liquid at room temperature. In order to avoid this, it is preferable to use an addition reaction type that does not generate any by-products during the curing reaction. This addition reaction type liquid silicone rubber composition is known and consists of an organopolysiloxane containing an aliphatic unsaturated group 1, such as a vinyl group (=SiVi group) bonded to a silicon atom in the molecule; The viscosity at 25°C is 300-500. OOQO8 may be added with noble metals such as platinum, rhodium, palladium, or their compounds, complex salts, etc. as a catalyst, and this organic peroxide vulcanized type has a viscosity of 300 to 500,000 OOc.
It is sufficient to add a known organic peroxide and, if necessary, atomized silica or precipitated silica as a reinforcing agent to the dimethylboroxytetraxane or dimethylmethylvinylpolysiloxane of No. 8. It may be a mixture of organic peroxide vulcanization types in a ratio of 80:20 to 20:80.

In addition, the thermosetting silicone rubber used here is an organopolysiloxane with a hydroxyl group or a trimethylsilyl group or a dimethylvinylsilyl group at the end of the molecular chain, an organopolysiloxane with a functional group such as a vinyl group in the molecule, and an organic polymer. A commercially available product generally called "mirable" which contains a vulcanizing agent such as an oxide may be used, and is not particularly limited.

The push button switch member of the present invention is made by measuring a predetermined amount of the silicone-modified epoxy resin described above, and then powdering it.
After inserting into the recess of the lower mold for molding, the above-mentioned liquid silicone rubber composition is poured onto it, or it is charged in powder form and heated, and then thermosetting silicone rubber is poured onto it. The silicone-modified epoxy resin can be obtained as an integrally molded product by placing the silicone-modified epoxy resin on the resin, attaching an upper mold for molding, and then applying heat and pressure. However, if this silicone-modified epoxy resin contains the above-mentioned curing catalyst.

This may be pre-treated by heat treatment in advance, or it may be dissolved in methyl ethyl ketone, tetrahydride tetrafuran, etc. and then impregnated into glass cloth, glass fiber, etc. and dried. Good too.

Next, this will be explained based on the attached drawings. In manufacturing this push button switch member, first, as shown in FIG. After heating this to 100 to 150 DEG C. to form a molten layer 4 as shown in FIG. 2, a liquid silicone rubber composition 5 is poured thereon. Then the third
figure.

As shown in Fig. 4, the molding medium 6 for forming the dome-shaped rubber elastic body is 1kl! Repair - Put the thermosetting silicone rubber 7 in this, place the molding upper mold 8 on it, heat and pressurize at 120-180°C and 5-30 kg/tri K, as shown in Figure 5. push button switch member 9
can be obtained as an integrally molded product. Note that this push button switch member 9 has a key top portion 1 made of epoxy resin.
0 and a dome-shaped elastic body part 11 made of silicone rubber, which usually has a contact part 12 made of conductive silicone rubber integrally molded in the center of the dome-shaped elastic body, and is used as a push button switch. It is put into practical use as a component.

As described above, in the push button switch member of the present invention, the structural body portion is firmly adhered to the cured film of the liquid silicone rubber composition. This gives you the advantage of being able to Mari 1
．． Since the key top of the push button switch member obtained in this way is made of plastic mainly made of epoxy resin, it has excellent hardness, strength, and abrasion resistance, and is also susceptible to static electricity. (Furthermore, various types of printing can be done on the surface using alkyd resin-based or ultraviolet curable printing ink. This means that various types of electricity such as desktop computers, typewriters, etc.
It can be advantageously used in keyboards for electronic devices.

Next, I will give an example of the present invention. The part in the example shows the overlapped part, and the viscosity shows the measured value at 25°C.
00) 70 parts of phenol novolak resin (phenol) containing 8 mol of aoN-phenylsiloxane units, both ends of the molecular chain blocked with hydroxyl groups, viscosity 5
00cS dimethyldiphenylborisyxane 5 parts, 2
- A mixture consisting of 0.3 part of phenylimidazole and 1.0 part of phthalocyanine blue was kneaded for 8 minutes with two 6-inch rolls at 90°C, and after cooling, it was crushed to have a particle size of 0.5 to
I made a silicone modified epoxy resin.

Next, 0.5 g of this silicone-modified epoxy resin was weighed and charged into the recess of the mold shown in Figure 1.
After heating it to a temperature of 1.5°C to make it into a molten state, it was made into an addition reaction type liquid silicone rubber KE-1920 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) with a viscosity of 3 (1,000 cS) and 0.
5.9 was cast, and then a medium mold was placed as shown in Figure 3, and then the thermosetting silicone rubber KE was poured.
-9610 (product name of Shin-Etsu Chemical Co., Ltd.) was charged with 3 g of a silicone rubber composition containing curing catalyst C-8 (product name of the same company), and the upper mold for molding was placed as shown in Figure 4. was placed and then heated and pressurized at 175° C. + 20 K9/crlK, whereby a push button switch member as shown in FIG. 5 was obtained as an integrally molded product.

The key top part of the push button switch member obtained here has a hardness of Shore D of 781 and a strength of 40 to 1000 rev (I
Kp load: 0817 wheel) 52, the key top portion and the dome-shaped rubber elastic body portion were completely adhered to each other, and when an attempt was made to separate them, the key top portion and the dome-shaped rubber elastic body portion were cut and destroyed.

[Brief explanation of the drawings] Figure 1 is a longitudinal cross-sectional view showing the charging of silicone-modified epoxy resin into the lower mold, and Figure 2 is a longitudinal cross-section after injecting the liquid silicone rubber composition into the lower mold. Figure 3 shows the vertical cross-section factor when a medium mold for molding a dome-shaped rubber elastic body and thermosetting silicone rubber are placed, and Figure 4 shows the vertical cross-section when a suppressing upper mold is further placed on it. The factors are shown in FIG. 5, which is a vertical cross-sectional view of a push button switch according to the present invention. 1... Lower mold - 2... Recessed part. 8.4...Silicone modified epoxy resin. 5...Liquid silicone rubber composition, 6...Medium size. 7... Thermosetting silicone rubber, 8... Upper mold. 9...Push button switch member, 10...Key top part. 11... Dome-shaped rubber elastic body part - 12... Contact part.

Claims (1)

[Claims] 1. Molding the key top part with thermosetting silicone-modified epoxy resin, applying a liquid silicone rubber composition to that surface, then placing thermosetting silicone rubber on it, heating and pressurizing it to integrally mold the push button switch member. A push-button switch member characterized by being