JP2781799B2 - Cover member for hard key top push button switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cover member for a hard key top push button switch, in particular, a key top portion made of a high hardness resin.
The present invention relates to a cover member for a hard key top push button switch , which is useful for telephones, OA equipment, home electric appliances, and the like.

[0002]

2. Description of the Related Art A cover member for a hard push button switch which has a good feel to the hard finger and excellent operability, and also has a good spring characteristic when pressed, has a skirt portion, a base portion and a contact portion made of silicone rubber. It is considered that the top part is formed by heating and curing a liquid material obtained by adding a curing agent, a coloring agent, etc. to oligomers or monomers alone such as acrylic, unsaturated polyester, methacrylic, or a combination thereof. ing. These have an advantage that they have a hard finger touch, and oil and fats such as esters do not permeate from the key top portion and contaminate the conductive contacts, and can be applied to thin products and products with large keys.

[0003] However, this kind of cover member for a hard push button switch is manufactured by forming a key top portion of a mold heated to a temperature at which a liquid material of a high hardness resin and an uncured silicone rubber are thermally cured. Carving filled with such injection device interrupt section, the liquid material is semi-cured, at but tacky is kept lost fluidity, thin movable part silicone rubber uncured, carving for base formation This is done by filling the filling part, integrating it with the previously filled key top part, completely curing it, and removing it from the mold. All of them cannot be processed by the device alone, and some of them are performed manually.

[0004]

However, in the method of manufacturing a cover member for a hard push button switch according to the conventional method ,
3 and as shown in the longitudinal sectional view in FIG. 4, the hard push button interrupt Carving of the key top portion 32 for molding of the switch cover member 31 <br/> viewed 4 2 high hardness resin 33 filled in the , carving because of its tendency to shrink heat curing molding process in the interrupt section 4 2, then the thin movable portion 34 and the base portion 35 and the silicone rubber 36 filled to form a can, at the original high hardness resin 33 in addition would Nde input Ri write to the part 37 of the key top portion 32 should be made form, there is a disadvantage that the size of the key top portion 32 itself accuracy evil Ru box. Also when filling the liquid material having high hardness resin 33 in the interrupt section 4 2 Carving, due to poor liquid surface leveling property of high hardness resins 33,
Irregularities Raw the boundary between the high hardness resin 33 and the silicone rubber 36
Flip is also disadvantageous in that Ru lowers the mechanical strength of the product.

[0005] Further, the key top portion made with the high hardness resins which are conventionally used, because they tend to yellow when heated, the silicon <br/> Kongomu apply sufficient heat during after-curing to remove low molecular weight siloxanes contained
Can not Rukoto, areas where low resistance is required in the contact portions
In addition , it is not possible to dry and harden the ink after printing characters etc. on the top of the key top part ,
There is a disadvantage that the adhesive strength of the ink is weakened. In addition,
Conventional high hardness resin forming the key top portion, the thermosetting is not completed, some as strong said skin irritation
There is also a slight problem with the irritating odor generated during heat curing.

[0006]

According to the present invention, a cover member for a hard key top push button switch according to the present invention is a methyl silicone resin.
Resin, phenyl silicone resin, dimethyl diphenyl resin
Silicone resin and methylphenyl silicone resin
The key top part made of a high-hardness silicone resin with a Shore D hardness of 40 or more selected from the key top part of the thin movable part and the base part made of elastic silicone rubber.
It is characterized in that it is formed integrally with the base part .

That is, the present inventors have conducted various studies to develop a cover member for a hard key top push button switch which solves the above-mentioned disadvantages and disadvantages of the prior art.
If work made by the high hardness silicone resin, the key after curing
In addition to Shore D hardness of the top portion is made to those of more than 40, hard
Of the previous ones is small skin irritation even liquid material, also be a polymer compound may be a low viscosity and liquid material, it is solidified without much to generate gas It is possible to obtain a key top portion having good dimensional accuracy by casting, since the material does not shrink during curing, and found that the thin movable portion and the base portion can be obtained. If it is formed of conventional silicone rubber, it will adhere well to the high-hardness silicone resin at the base of the key top portion, so that the desired cover member for the hard key top push button switch can be easily and advantageously integrated. Molding
Ensure that can be obtained as to the present invention has been completed. This will be described in more detail below.

[0008]

[Action] hard key top cover member for push button switch of the present invention, the key top portion is Shore D hardness made form more than 40 of the high hardness silicone resin, in addition to having excellent hard finger touch, fats Also has the effect of preventing the penetration of minutes,
Since no contract upon heating may dimensional accuracy, the silicone rubber of the thin-walled movable portion and the base portion covers the key top portion is also referred to as nor yellowing upon heating
It has advantages . Further, there is no fear that the film is accompanied by film irritation or pungent odor during production.

[0009]

High hardness silicone resin used in the key top portion have your hard key cover member for the top push button switch of the present invention DETAILED DESCRIPTION OF THE INVENTION, the chemical structure is the backbone siloxane
Although silicone resin that has a down skeleton is found using, this crosslinking density is high, easily obtained a three-dimensional crosslinked structure, is preferably easily obtained silicone resin also block copolymers
No.

The high-hardness silicone resin is selected from methyl silicone resin, phenyl silicone resin, dimethyldiphenyl silicone resin and methylphenyl silicone resin , and these give a molded product having a high Shore D hardness of 40 or more. Furthermore, to the high-hardness silicone resin may be a liquid material low viscosity even polymeric material, because during thermal curing shrinkage is small good dimensional accuracy, thus interrupt portion carving for the key top portion formed in be cured, to where the thin movable portion and does not mix the silicone <br/> Ngomu for the base portion, the liquid material surface cohesive energy is low, when heated viscosity reduction accelerated above 100 ° C. Therefore , when the resin is dropped and filled into the mold, it easily levels in the mold, and the boundary between the silicone rubber and the silicone rubber to be filled thereafter is not uneven.

Further , since this high-hardness silicone resin has a siloxane bond in the main chain, even if it is in a liquid state before curing, it has low skin irritation and causes eczema and rash even if used for a long time. There is no danger, and the key top made from this does not turn yellow even when heated, so sufficient heat treatment is possible, and the adhesion to letters, symbols, etc. printed on the top of the key top is strong Have the advantage of becoming
In addition , since the obtained key top part has excellent heat resistance, cold resistance, ozone resistance, and chemical resistance, the cover member for the hard key top push button switch using this has a hard finger touch, It has the advantage of having excellent environmental characteristics because it has a permeation-preventing property.

The viscosity of the liquid material of the high-hardness silicone resin may be any, but it is preferable that the viscosity is not more than 500 poise for filling in a mold. Dropping and filling can be performed with a discharge device, for example, a plunger pump dispenser, a roller tube pump dispenser, a piano touch tube pump dispenser, an air dispenser, or the like. In addition,
Curing mechanism of the high hardness silicone resin forming the key top portion is an addition reaction, radical reaction, it may be adopted any of the co-reaction of the addition reaction and radical reaction.

The key top thus produced may be printed or painted with characters such as letters, numbers, and symbols on the top surface. In this case, the key top has a high hardness as described above. Because it is made of silicone resin,
The inks and paints used here are preferably composed of the same or similar components as this high-hardness silicone resin, with a coloring agent, a crosslinking agent, a diluent, etc., for example, the key top part is made of methyl silicone resin. In this case, the ink or paint is also of a methyl silicone resin type, and when it is made of a phenyl silicone resin, the ink or paint is preferably of a phenyl silicone resin type. This printing ink has an addition reaction, a condensation reaction,
Consists of radical reaction or addition reaction and radical reaction
Cured by any reaction mechanism of co-reaction.

[0014] On the other hand, the thin movable portion and the base portion of the cover member for push button switch of the present invention is being created made of silicone rubber having elasticity, the silicone rubber is used in the manufacture of the cover member for push button switch conventionally In particular, the average unit formula of the thermosetting type is _Ra
Represented by SiO _{4-a / 2} , wherein R is an alkyl group such as a methyl group, an ethyl group, a propyl group, or a butyl group, an alkenyl group such as a vinyl group or an allyl group, an aryl group such as a phenyl group or a tolyl group, or The same or different unsubstituted or substituted chloromethyl groups, trifluoropropyl groups, cyanoethyl groups, etc., in which part or all of the hydrogen atoms bonded to the carbon atoms of the group are substituted with halogen atoms, cyano groups, etc. The monovalent hydrocarbon group may have a in which a is from 1.90 to 2.05, wherein at least 80 mol% of R is a methyl group and 0.1 to 0.5 mol% is a vinyl group. C., the viscosity at 25 ℃ is 100c S or more, preferably it is preferred to those based on organopolysiloxane is 1,000C S or more, which is be of a self-adhesive also Kill.

The silicone rubber is generally compounded with a silica filler. Examples of the filler include fumed silica, wet silica, quartz powder, and diatomaceous earth. However, it is preferable that these particles have a particle size of 50 μm or less, and the addition amount is preferably in the range of 20 to 200 parts by weight based on 100 parts by weight of the organopolysiloxane. This composition may contain a silane containing an alkoxy group, a silanol group or the like as a dispersant, and may further contain an inorganic or organic pigment for coloring.

The silicone rubber composition contains a cross-linking agent for curing the silicone rubber composition. The silicone rubber composition preferably has a one-minute half-life of 120 ° to 180 ° C. or less. Peroxide, dichlorobenzoyl peroxide, butylperoxy-2-octylhexanate, 2,5-dimethyl-2,5-dibenzoylperoxyhexane, butylperoxylaurate, cyclohexane peroxide, butylperoxyisopropyl carbonate, those radical reaction type exemplified by such butylperoxy allyl carbonate is employed
You. In this silicone rubber composition, the organopolysiloxane contains an aliphatic unsaturated group such as an alkenyl group, and the organopolysiloxane contains at least two hydrogen atoms bonded to silicon atoms in the molecule. An addition reaction type comprising empolysiloxane and chloroplatinic acid or a platinum-based complex, or a platinum catalyst comprising a complex salt of chloroplatinic acid and an alcohol, aldehyde, olefin, or vinylsiloxane may be used.

[0017] To obtain a hard key top cover member for push button switch of the present invention, the crosslinking agent optionally to the high hardness silicone resin uncured, the curing agent, a coloring agent, a liquid material or the like is added stabilizers, the both of the silicone rubber of the liquid and uncured interrupt portion engraving for the key top portion forming the mold being heated to a temperature capable thermosetting, dropwise filled by using a discharge device, the liquid material semi-cured, but is kept tacky was lost its fluidity, filling the silicone rubber of the uncured thin movable portion, the interrupt unit engraving for base formation,
Integrated with the key top portion is filled earlier with the key top portion base it is sufficient to completely cure. Although some of the compounding step of the molding operation and the liquid body also rely on manual, the liquid material is skin irritation less,
This operation can be performed safely because the gas generated during the heat curing is also less irritating.

The cover member for a hard key top push button switch of the present invention thus produced is shown in FIG.
As shown, the key top portion 2 of the rigid key tops for push button switch cover member 1 is <br/> work made by the high hardness of the silicone resin 3, a thin movable portion 4 and the base part 5 has elasticity Although the work made of silicone rubber 6, since the high-hardness silicone resin 3 is of good low leveling property of the surface cohesive energy, high hardness silicone resin 23 as shown in FIG. 2 is a key top portion for forming be easily leveled in the carving interrupt unit 22, a silicone rubber 6 which is filled in here, the unevenness in the key top base portions 7 of the boundary of their occurrence
Without Rukoto to be integrally molded.

[0019]

Next, examples of the present invention and comparative examples will be described. Example 1 Dimethyldiphenylsilicone resin as a high-hardness silicone resin, X321195 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) 100 parts by weight of crosslinking agent CX-1195 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) 10 parts by weight , Curing catalyst X-93-555
[Trade name of Shin-Etsu Chemical Co., Ltd.] A base material containing 0.4 parts by weight, and a colorant / STVX683
A key heated to 150 ° C. using an air dispenser AD3000VH [trade name of Iwashita Engineering Co., Ltd.] was added to a mixture obtained by adding 1 part by weight of [Daneichi Seika Industry Co., Ltd.]. was added dropwise charged into interrupt portion engraving for the top portion formed.

Then, the dropped liquid is semi-cured,
30 seconds after the loss of fluidity, silicone rubber compound KE-9510U [trade name of Shin-Etsu Chemical Co., Ltd.] 100
A crosslinking agent, PERHEXA 25B [manufactured by NOF Corp. trade name made by blending 1 part by weight of the formulation was filled into interrupt portion engraving of a mold for forming a thin movable portion and the base portion to the weight parts, the molding pressure
When heat compression molding was performed under the conditions of 100 kg / cm ² and molding time of 10 minutes, the key top part was the thin movable part and the key of the base part .
It is integrally molded cover member for push button switch obtained in the top section base.

Next, 20 parts by weight of titanium oxide A-220 (trade name, manufactured by Ishihara Sangyo Co., Ltd.) was added to 100 parts by weight of the above dimethyldiphenyl silicone resin on the top surface of the key top portion of the cover member for the push button switch, and kneaded. Then, a white paste-like ink having a viscosity of 300 poise with toluene as a diluent was screen-printed and dried in a drying oven at 200 ° C. for 60 minutes. Since the key top part is made of the above-mentioned high hardness silicone resin, it has an excellent hard finger touch because it has a Shore D hardness of 40 or more, has a good appearance, does not yellow when heated, and has an unusual odor. Nonetheless, the adhesion between the key top portion and the thin movable portion and between the key top portion and the ink were strong and reliable.

Embodiment 2 The cover member for the hard key top push button switch of Embodiment 1 is
After molding 100 sheets, the presence or absence of the silicone rubber wrapping around the key top part, the yellowing of the key top part, and the dimensional accuracy of the pitch (key pitch) between the key top parts were determined. As shown in the figure, the number of wraparounds of the silicone rubber and the dimensional accuracy of the key pitch were poor as few as 5 sheets, and no yellowing occurred.

COMPARATIVE EXAMPLE 1 A conventional hard key top push button switch cover member was molded in the same mold as in Example 1 except that only the key top portion was formed of an acrylic resin, and whether or not the silicone rubber wrapped around the key top portion. yellowing of the presence or absence of the key top portion, where it is determined the quality of the dimensional accuracy of the pitch (key pitch) between the key top portion, Ri Contact and was shown in Table 1 below, the silicone rubber wraparound and key pitch of dimensional accuracy of There were as many as 85 bad ones, all yellowing.

[0024]

[Table 1]

Example 3 The cover member for a hard key top push button switch of the present invention obtained in Example 1 was after-cured under the drying furnace conditions shown in Table 2, and the yellowing of the key top portion, the degree of polymerization, 10 following measurement by gas chromatography of the low molecular siloxane content, was subjected to a scratch test of printed characters by the nail for adhesion strength confirmation of the ink, also shown in Table 2
Were with your is, the yellowing of the key top portion not also not occur in any condition, 200 ° C. for at least 15 minutes if it is possible to take into drying furnace adhesion strength of the ink is also substantially better low molecular siloxane content is also 1,000 ppm or less I was able to.

[0026] After the conventional hard keytop push button switch cover member formed with an acrylic resin key top portion obtained in Comparative Example 2 Comparative Example 1, in the same manner as in Example 3 in a drying furnace conditions shown in Table 2 Cure, yellowing of key top part, polymerization degree 10
Was examined the adhesion strength of the ink by scratching test according pawl for confirmation of adhesion strength measurement and ink by gas chromatography of the low molecular siloxane content of less, next result of As are shown in Table 2, complete adhesion Under the drying conditions for obtaining the strength, the key top portion was yellowed, and conversely, at a temperature not yellowing, only an insufficient adhesion strength was obtained.

[0027]

[Table 2]

[0028] was examined by using a monitor of 7 people the production at the time of the pungent smell of hard key top cover member for push button switch of the fourth embodiment the present invention,
All as shown in Table 3 did not feel the pungent odor.

[0029] Comparative Example 3 for conventional hard keyboard cover member for push button switch manufactured by the method used in Comparative Example 2, using the seven monitor odor vapor generated during thermal curing during fabrication
Where tone solid, the results of as shown in Table 3 of the following was obtained.

[0030]

[Table 3]

[0031]

According to the cover member for a hard key top push button switch of the present invention , the key top portion has a Shore D hardness of 40 or more.
Since the serial has a high hardness degree silicone resins, there is a rigid finger touch, even when heated without yellowing, also silicone rubber key top portion when integrally molded with silicone rubber so that excellent dimensional precision There is no fogging, and no irregularities occur at the boundary between the key top portion and the silicone rubber . In addition, the high-hardness silicone resin in liquid form before curing does not have skin irritation or irritating odor, so it is safe to work and prints characters and symbols provided on the top surface of the key top part , adhesion to painted surface This has the advantage of being good.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a cover member for a hard key top push button switch of the present invention.

During the production of rigid key tops for push button switch cover member of the present invention; FIG is a longitudinal sectional view showing the leveling of the high hardness silicone resin in the interrupt portion carving of the key top portion for forming.

FIG. 3 is a longitudinal sectional view of a conventional cover member for a hard key top push button switch.

[4] in the manufacture of conventional hard keytop pushbutton switch cover member is a longitudinal sectional view showing the leveling of the high-hardness resin liquid material in the interrupt portion carving for the key top portion formed.

[Description of Signs] 1 , 31 ... cover member for push button switch, 2, 32 ... key top part, 3, 23, 33 ... high hardness silicone resin, 4, 34 ... thin movable part, 5, 35 ... base part, 6 , 36 ... silicone rubber, 7 ... key top base portions, 22, 42 ... Carving interrupt unit, 37 ... silicone rubber yelling around a portion of the key top portion.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01H 13/14 H01H 3/12 H01H 11/00

Claims (5)

(57) [Claims] 1. A methylsilicone resin, phenylsilico
Resin, dimethyldiphenyl silicone resin and
Shore D selected from methyl phenyl silicone resin
Key made of high-hardness silicone resin with hardness of 40 or more
The top portion, made of silicone rubber having elasticity
The thin-walled moving part and the base of the key top part of the base
A cover member for a push button switch of a hard key top portion characterized by being formed. Wherein said high hardness silicone resin is cured before
The cover member for a hard key top push button switch according to claim 1, wherein the viscosity of the cover member is 500 poise or less. Wherein the high hardness silicone resin, addition reaction,
Radical reaction or addition reaction and radical reaction with coreactant either hard key top cover member for push button switch of claim 1, wherein those which are cured by reaction Organization of consisting of. Wherein said silicone rubber is an addition reaction or any hard key tops for push button switch cover member according to claim 1, wherein those which are cured by reaction mechanisms of radical reaction. 5. The printing head according to claim 1, wherein the key top portion is formed on a top surface thereof by a printing ink which is cured by any reaction mechanism of an addition reaction, a condensation reaction, a radical reaction or a co-reaction composed of an addition reaction and a radical reaction. Signs such as letters and symbols are provided
The cover member for a hard key top push button switch according to claim 1, wherein