JPH06101274B2 - Cover member for rubber switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention has a cover member for a rubber switch, and in particular, has a glossy surface similar to plastic, metal, etc. in terms of appearance, design and finger feel. In addition, the present invention relates to a rubber switch cover member that is useful for calculators, remote controllers, telephones, etc., in which the characters displayed on the key tops are not worn.

(Prior Art) The cover member for key switches is generally made of synthetic rubber such as silicone rubber, chloroprene rubber, ethylene propylene rubber, etc., but its moldability, pressing force as a switch, restoring force, and ensuring elasticity etc. From this point of view, rubber with a hardness of about 30 to 70 Hs is used for this, and since this mold is also considered as a matte surface in terms of manufacturing cost, this product usually has a hard surface. It has a matte surface of 30 to 70 Hs.

However, since this surface has a matte surface, it has many demerits in terms of appearance, and since it is made of rubber, it has adhesiveness and cannot be smoothly pressed. Also,
Since the rubber having a character display consisting of an ink layer on the key top part is too soft, the ink layer can not follow the deformation of the rubber when repeatedly pressed and may peel off, so recently hard plastic, Although the use of metal key tops is increasing, they have the disadvantage of being expensive.

(Structure of the Invention) The present invention relates to a cover member for a rubber switch that solves such disadvantages. The cover member for a key top made of rubber is 1) General formula R ¹ Si (OH) ₃ (where R ¹ is a silicone compound represented by an organic group having 10 or more carbon atoms, and 2) A) a general formula. (Wherein R ² is the same or different monovalent hydrocarbon group selected from methyl group, ethyl group, vinyl group and phenyl group, l
Is a vinyl group represented by 100 to 10,000) 0.05 to 3.0
100 parts by weight of organopolysiloxane containing mol%, B) General formula R ³ mSiO _{4 -m / 2} (R ³ is the same or different monovalent hydrocarbon group selected from methyl group, vinyl group and phenyl group, m Is 5 to 50 parts by weight of an organopolysiloxane containing 0.1 to 10 mol% of a vinyl group represented by 1 or 2), and C) a general formula. (Wherein R ⁴ is a hydrogen atom, an atom or a group selected from a methyl group, an ethyl group, and a phenyl group, n is an integer of 10 to 1,000), and hydrogen bonded to at least two silicon atoms in the molecule. 0.5 to 30 parts by weight of an atom-containing organohydrogenpolysiloxane, D) a mixture of a catalytic amount of platinum or a flexible silicone resin component containing a platinum compound in a weight ratio of 1: 1 to 1:30. A reactive transparent organopolysiloxane composition is diluted with a solvent such as toluene, xylene, or mineral spirits as needed, and is applied and dried. A flexible transparent film layer having a surface hardness of 70 to 95 Hs. And a surface having a gloss level of 35 to 95% is formed.

That is, as a result of various studies on the method of modifying the conventional cover member for a rubber switch having a matte surface, the present inventors have found that the above-mentioned surface of the key top portion of the rubber switch member formed by molding rubber is used. By providing a transparent silicone-based coating layer, the surface of this key top has a hardness of 70 to 95 Hs.
And, if the glossiness is 35 to 95%, this key top part has the same excellent appearance as hard plastic and metal, and since it is not sticky, the pressing operation is smooth. In addition, it is found that the character display can be of an excellent quality in that the character display is covered with a light-transmitting (transparent) film layer so that the character is not peeled or worn. In order to make the surface of this type of rubber switch cover member glossy, it was necessary to polish the surface of the molding die, which greatly increased the cost of manufacturing the die. It was confirmed that the target product can be obtained at a low cost because it is sufficient to form a silicone-based transparent film layer, and the present invention was completed by conducting research on the type of silicone used here and the processing method.

The shape, material, and color tone of the rubber switch cover member of the present invention may be those used in the push button portion of the known switch member (keyboard cover member) of this type, and therefore the sliding portion is opposite to this. Elastic arm rods made of elastic, push button elastic metal plate bodies having different sizes, strokes, loads, and appearances can be appropriately selected and used in combination. The elastic switch member is made of natural rubber or diene-based synthetic rubber such as polybutadiene, polyisoprene, SBR, and neoprene, ethylene-propylene-based, urethane-based, polyester-based, silicone-based synthetic rubber, or a combination thereof. However, it is preferable to use a silicone rubber having excellent heat resistance, weather resistance and electric insulation. On the other hand, for those using a metal plate, those made of stainless steel, phosphor bronze, beryllium copper, or those plated with gold or silver on which a plate-shaped body is pressed into an inverted arm to impart elasticity And it is sufficient. In addition, it is optional to apply an appropriate primer to the joint portion with the silicone rubber in order to enhance the adhesiveness with the silicone rubber described later.

The switch member may be either entirely insulative or electrically conductive, but normally the contact portion is electrically conductive and the dome portion is electrically insulating. It may be made by a large number of known methods such as compression molding, injection molding and transfer molding.

The molded switch member made of rubber has a silicone-based transparent coating layer formed on the surface of the key top portion thereof to be a cover member for a rubber switch. This silicone-based transparent coating layer is formed. As the silicone (paint), a silicone compound represented by the general formula R ¹ Si (OH) ₃ (where R ¹ is an organic group having 10 or more carbon atoms) dissolved in toluene, xylene, etc. may be used. In order to impart flexibility, 1) a silicone compound represented by the general formula R ¹ Si (OH) ₃ (where R ¹ is an organic group having 10 or more carbon atoms), and 2) A) a general formula (Wherein R ² is the same or different monovalent hydrocarbon group selected from methyl group, ethyl group, vinyl group and phenyl group, l
Is a vinyl group represented by 100 to 10,000) 0.05 to 3.0
100 parts by weight of organopolysiloxane containing 100% by mole, B) General formula An organopolysiloxane containing 0.1 to 10 mol% of a vinyl group represented by (R ³ is the same or different monovalent hydrocarbon group selected from a methyl group, a vinyl group and a phenyl group, and m is 1 or 2) 5 50 parts by weight, C) general formula (Wherein R ⁴ is a hydrogen atom, an atom or a group selected from a methyl group, an ethyl group, and a phenyl group, n is an integer of 10 to 1,000), and hydrogen bonded to at least two silicon atoms in the molecule. 0.5 to 30 parts by weight of an organohydrogenpolysiloxane having atoms, D) a flexible silicone resin component comprising a catalytic amount of platinum or a platinum-based compound and mixed at a weight ratio of 1: 1 to 1:30 If necessary, an addition reaction type organopolysiloxane composition may be added with toluene,
It may be diluted with a solvent such as xylene or mineral spirit, applied to a place where a film layer is to be formed, and then heated at 200 ° C. for an hour to be cured.

The general formula of the flexible silicone resin component R ² mSiO _{4-m / 2} and If the weight part of the product is outside the specified range, the gloss will not be within the range of 35 to 95% and the gloss will be lost and the appearance will be inferior. May become difficult to recognize, and the surface hardness may not fall within the range of 75 to 95 Hs, and the pressing operation may not be smooth.

The ratio of the silicone compound represented by the general formula R ¹ Si (OH) ₃ to the flexible silicone resin component must be 1: 1 to 1:30, which is represented by R ¹ Si (OH ₃ ). If the amount of the silicone compound contained is greater than that of the flexible silicone resin component, the flexibility as a rubber switch cover member will be lost and the pressing operation will not only deteriorate, but also the transparent film layer on the key top will be cracked with repeated pressing. However, if the flexible silicone resin component is blended in excess of the specified ratio, the glossiness will not change, but the surface hardness will be 75-95Hs.
It will not fit in the range of and the pressing operation will not be smooth.

Since this coating layer is transparent (translucent), the rubber switch cover member may be colored in advance if desired. Also, when a character display is printed on the key top, the silicone-based transparent film layer covers the character display,
Peeling and abrasion of the character display will not occur.

If the characters are made of rubber other than silicone rubber, the surface of the transparent coating layer should be treated with a silicone primer composition and a surfacer in order to firmly adhere it to the rubber switch member. It is good to have

Next, the rubber switch cover member of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a vertical sectional view of a rubber switch cover portion 1 of the present invention, which is a key top of a rubber switch member including a key top portion 2, a dome portion 3 and a leg portion 4. Although the silicone-based transparent coating layer 5 is provided on the surface of the portion 2, this may be provided by previously printing the character display 6 on the surface of the key top portion 2.

(Effect) The rubber switch cover member 1 of the present invention is provided with a silicone-based coating layer on the surface of the key top portion 2. This silicone-based coating layer is made of the thermosetting silicone paint as described above. It has a hardness of 70-95Hs, for example 80-95Hs and a gloss of 35-95%, for example 60-85%, so it can be made of hard plastic or aluminum, chrome etc. Since it has the same glossiness as that of metal, the appearance is different from that of rubber, and its finger feel is not sticky like the conventional rubber switch cover member, but it is pressed. There is an advantage that the operation can be carried out smoothly and the displayed characters are not peeled off or worn.

Next, examples of the present invention will be given. Parts in the examples are parts by weight, and viscosity is a measured value at 25 ° C. Hardness and glossiness of test results are as follows. The measured values are shown.

〔hardness〕

It is measured by the spring hardness test method described in JIS K6301 Physical property test method for vulcanized rubber.

However, the hardness of the silicone-based transparent coating layer can be measured with the spring hardness tester if the sample thickness specified in JIS K6301 can be stacked up to 6 mm, but if it is less than this, for example, up to about 1 mm. When it can only be overlapped, the Wallace micro hardness tester H5A (The Wallace micro h
ardness Tester H5A) using TRHD unit (British & Int
This is measured with the International Rubber Hardness Degrees) and converted to JIS hardness Hs.

[Glossiness]

Measured by the specular gloss measurement method specified in JIS Z8741, this is a specular surface at an incident angle of 60 degrees on a glass surface with a constant value of 1.567 over the entire visible wavelength range using the 60 degree specular gloss method. The gloss value is expressed as 100%.

Example A mixture of 100 parts of thermosetting silicone rubber KE 961U [trade name of Shin-Etsu Chemical Co., Ltd.] and 2 parts of curing agent C-8 [trade name of the same company] sandblasted with Morundum # 100 on the surface Put in the processed mold, 180 ℃, 200kg / cm ²
When a rubber switch member was made by heating and pressure molding under the conditions, the key top of this product had a hardness of 58 Hs and a gloss level.
It was 0.8%.

Next, after printing letters and numbers on this key top with Sylmark [trade name of Shin-Etsu Chemical Co., Ltd.] ink, the general formula R ¹ Si (OH) ₃ (R ¹ has 17 carbon atoms) Organic compounds) and the formula 100 parts by weight of an organopolysiloxane containing 2 mol% of a vinyl group represented by and an organopolysiloxane containing 5 mol% of a vinyl group represented by R ³ nSiO _{4-m / 2} (R ³ is a methyl group or a vinyl group). 30 parts by weight of siloxane, formula (R ⁴ is hydrogen atom, methyl group) Organohydrogenpolysiloxane represented by 20 parts by weight and platinum 0.5 parts by weight of a flexible silicone resin component of 1:10 by weight ratio of addition reaction type Organopolysiloxane composition
To 100 parts of toluene 90 parts by weight of isopropylene alcohol 6
After coating with 0 parts, the thickness after solvent drying is 30 μm.
After forming a coating film that is, it was heated at 200 ℃ for 30 minutes to cure this coating film to make a flexible transparent silicone film layer. 80Hs, 85% gloss, and the characters on the key top were clearly visible because the silicone film layer was transparent.

The rubber push-button switch cover member is covered with a silicone film layer so that the characters are not peeled or worn even after 500,000 touches, and the characters are clear. Since there is no adhesiveness, the pressing operation was smooth.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of the rubber switch cover member of the present invention. 1 ... Rubber switch cover member, 2 ... Key top part, 3 ... Dome part, 4 ... Leg part, 5 ... Silicone film layer, 6 ... Character display.

Claims (1)

[Claims] 1. A silicone compound represented by the general formula R ¹ Si (OH) ₃ (wherein R ¹ is an organic group having 10 or more carbon atoms) on the surface of a rubber key top, and 2) A) general. formula (Wherein R ² is the same or different monovalent hydrocarbon group selected from methyl group, ethyl group, vinyl group and phenyl group, l
Is a vinyl group represented by 100 to 10,000) 0.05 to 3.0
100 parts by weight of organopolysiloxane containing mol%, B) General formula R ³ mSiO _{4 -m / 2} (R ³ is the same or different monovalent hydrocarbon group selected from methyl group, vinyl group and phenyl group, m Is 5 to 50 parts by weight of an organopolysiloxane containing 0.1 to 10 mol% of a vinyl group represented by 1 or 2), and C) a general formula. (Wherein R ⁴ is a hydrogen atom, an atom or a group selected from a methyl group, an ethyl group, and a phenyl group, n is an integer of 10 to 1,000), and hydrogen bonded to at least two silicon atoms in the molecule. 0.5 to 30 parts by weight of an organohydrogenpolysiloxane having atoms, D) a mixture of a catalytic amount of platinum or a flexible silicone resin component composed of a platinum compound in a weight ratio of 1: 1 to 1:30. A rubber, characterized in that it is a flexible transparent film layer made of a reactive organopolysiloxane composition and has a surface hardness of 70 to 95 Hs and a gloss of 35 to 95%. Switch cover member.