JPH08281703A - Manufacture of key-top-integrated keyboard switch - Google Patents

Abstract

PURPOSE: To improve the wear resistance of a two-color molded switch having high using frequency by surrounding the periphery of each key with a skirt part having a specific thickness, and using composition having specific hardness and containing aromatic polyester polymer as a main ingredient as a thermoplastic elastomer composition for a molding in which the entirety is connected with the periphery formed as a platelike part. CONSTITUTION: A key top group 6 injected by a plurality of pin gates 2 from a fixed side mold plate 1 is molded by thermoplastic resin in a first mold, the plate 1 is replaced with a second mold while the key top molding remains stuck to a movable side mold plate 5, the elastomer composition is injected from a pin gate 10 provided on the rear surface of each key, heat fusion bonded to the rear surface of each key top, integrated from the gate 10 provided with each key, the periphery of each key is surrounded by a thin skirt part 12 having a thickness of 0.1 to 0.25mm, and a molding in which the entirety is connected with the periphery as the plate state. The composition having hardness JISA 75 to 95 degrees and containing the aromatic polyester polymer as a main ingredient is used for the elastomer composition used here.

Description

Detailed Description of the Invention

[Field of Industrial Application] In addition to telephones, the present invention relates to switches (hereinafter referred to as SW) in various fields such as general household appliances, OA electric equipment, transportation machines, and general machines. In particular, the present invention is a push button type SW, and since the character portion of the display is formed in two colors, it does not disappear forever. Therefore, it is suitable for a switch that is heavily used or a device that is used in a bad environment. Further, although it is necessary to use a two-color molding machine for the key top and the SW part, an integrated product can be manufactured in one step, so that it can be rationalized significantly and the cost can be made lower than before. In addition, since the character display portion is a thermoplastic elastomer (hereinafter referred to as TPE), it is hard to slip when touched with a finger and is unlikely to be pressed by mistake. Furthermore, if you get used to it, you can distinguish the numeric characters by touching your fingers, which is convenient for use by amblyopia and blind people. It can also be used for welfare-related SW.

[0002]

2. Description of the Related Art A keyboard switch (hereinafter referred to as KBSW) is simply a group of SWs. A phone near me,
There are remote controllers for TVs and AVs, remote controllers for air conditioners, pocket computers (personal computers), personal computers, etc., but the most used of these is silicone rubber KBS.
W. In a telephone, a personal computer, and a slightly higher-grade pocket computer, a resin key top is placed on the silicone rubber KBSW. In these KBSWs that are frequently used, if the display on the upper surface of the key is printed and may be worn away, the resin key top formed by two-color molding is usually used. For example, of the telephone switches SW, almost all non-home telephones called business phones are KBSWs using a two-color molded key top. The two-color molding is considered to be a completed technology, and the key top is also inexpensive, but when looking at the switch as a whole, several steps are required, so the price is silicone rubber KBS.
It will be an additional price for W parts and resin key top parts. In that sense, there is room for rationalization.

[0003]

[Problems to be solved] There is a need for a technology that has the advantage of a two-color molded key top in which the display does not disappear permanently, and has the function of a SW at the same time, and that can be supplied at a low cost comprehensively in a short process To be Also, the SW of "5" is provided with a small protrusion in the center for the blind and amblyopia, but it should be easier to understand. By analogy with the knowledge gained in the past, thermoplastic elastomers (TP
E) is considered and can be seen in patents. Therefore,
If the resin of the key top and the TPE as the SW material have a property of being heat-sealed to each other, the key top and the SW portion can basically be integrally molded. In addition, in order to make the above-mentioned technique more meaningful, the present inventor can perform both the two-color molding of the key top display and the two-color molding of the fusion of the key top and the SW part by one two-color molding. I thought it was effective to do. However, this cannot be performed by using the conventional two-color molding method.
This is because the purpose of conventional two-color molding was not for such usage. Also, in the case of character display by two-color molding, there are very few examples in which the thermoplastic elastomer is used for the character part, since it is only temporarily used in the AV home appliance SW. In particular, there is no example of a frequently used SW such as the telephone KBSW. It is considered that the abrasion resistance of the thermoplastic elastomer is generally lower than that of the resin, which has stopped the idea.

[0004]

The present inventors have arrived at the present invention as a result of diligent efforts to solve the above problems.
That is, according to the present invention, a movable mold plate having the same or the same shape is used for the first mold and the second mold, and in the first mold, the thermoplastic resin is injected from the fixed mold plate with a plurality of pin gates to form a key. A pin gate in which a top group is molded, and thereafter, the fixed side template is replaced with a second mold while each key top molded article is attached to the movable side template, and the thermoplastic elastomer composition is provided on the back surface of each key. It is injected from the bottom of each key top and heat-bonded to the back surface of each key top to integrate each key and the thickness around each key is 0.1
A push-button switch is obtained by enclosing a skirt with a thin skirt of 0.25 mm and connecting the whole with the periphery of the skirt as a plate. A method for producing a keyboard switch integrated with a keytop, characterized in that a composition comprising an aromatic polyester polymer as a main component and having a hardness of JIS A 75 to 95 degrees is used in a thermoplastic elastomer composition. Is. In addition, the key top is molded so that the thermoplastic resin does not enter into the character part by making a character-shaped protrusion in the part of the fixed mold plate of the first die that contacts the back surface of each key. The key top integrated type characterized in that the thermoplastic elastomer composition enters into the second mold and the thermoplastic elastomer composition displays characters and the like in the thermoplastic resin on the key top surface. A method for manufacturing a keyboard switch can be provided. Furthermore, in the part of the movable side template that touches the upper surface of each key, a pin is installed on the movable side template in the part corresponding to the character that has an island area separated from the outside in part of the display character. However, at the time of injection with the first mold, the pin tip is slightly inserted in the switch side from the height of the key top upper surface, and when ejecting with the second mold, the pin tip should be returned to the same surface as the key top upper surface height. The present invention provides a method for manufacturing a keyboard switch integrated with a keytop, which is provided with a mechanism capable of performing the above.

The present invention will be described in detail below. First, the materials used will be described. The thermoplastic polyester elastomer composition used in the second mold preferably contains a thermoplastic polyester elastomer (hereinafter TPEE) in an amount of 50 to 100% by weight, more preferably 60 to 10%.
The content of 0% by weight, more preferably 70 to 100% by weight, is used, and the TPEE is preferably aromatic. The preferred TPEE is described in detail below.

The TPEE polymer is preferably a polymer compound in which a hard segment such as an aromatic high melting point crystalline polyester is linked to a soft segment such as a low melting point polyether or polyester block.
The polyester unit of the hard segment is composed of an aromatic acid component and a polyol component. The acid component is preferably terephthalic acid. The polyol component is preferably a glycol having 2 to 12 carbon atoms, butane diol is particularly preferable. When the polyalkylene glycol unit is used as the low melting point polymer segment which is the soft segment,
Polyethylene glycol, polypropylene glycol,
Polytetramethylene glycol and the like can be preferably used. When using an aliphatic polyester unit, succinic acid, adipic acid, sebacic acid, as an acid component,
Decanedicarboxylic acid has 2 to 2 carbon atoms as a diol component.
Twelve glycols can be preferably used. The hard segment and the soft segment are 70:30 to 30:
Those copolymerized in a weight ratio of 70 are most preferably used as the TPEE of the present invention. Since the above-mentioned TPEE has a high melting point among the thermoplastic elastomers, it has a small creep property and a high abrasion resistance even at a relatively high temperature. That is, it is close to rubber. Also, the glass transition temperature is sufficiently low, which is also close to that of rubber. Therefore, the brittleness at low temperature is small.

As the TPEE composition, the above-mentioned TPEE is used.
Used in an amount of 50 to 100% by weight. TPEE
Other than these, rubber, a plasticizer, a pigment, other additives, and the like are included. Various compositions have been devised depending on the application, and there are also components added to improve moldability. For example, the addition of a proper amount of rubber increases the durability of the bent portion. Further, addition of a plasticizer is very effective in adjusting the hardness of the composition. The TPEE composition is, for example, K for telephones
When used in BSW, it is required to have excellent moldability to withstand mass production, excellent keystroke durability (repeated bending resistance), and controllability of hardness to match the desired button pressing pressure. The hardness of the TPEE composition suitable for the present invention is 75 to 95 degrees in JIS A, and more preferably 80 to 93 degrees. If it is 75 degrees or less, the abrasion resistance of the key top display portion tends to be poor. At 93 degrees or higher, the SW is too hard to fit in. The thermoplastic resin used for the key top can basically be used if it has a heat fusion property to the TPEE composition used. The polycarbonate resin was the best in the heat fusion test results for the TPEE composition that is preferably used in the present invention. That is, a polycarbonate resin (hereinafter referred to as PC) or an alloy of PC and ABS resin could be preferably used.

The mold structure and molding method will be described. FIG.
Shows an example of the structure of the first mold. 1 is a fixed-side template, 2 is a pin gate, and 3 and 4 are protrusions in the shape of letters and numbers. 3 indicates the case of letters and numbers such as "4" and "6" with island areas in the letters, and 4 indicates the case of letters and numbers such as "2" and "5" that does not include island areas. There is. Reference numeral 5 is a movable side mold plate, and 6 is a hollow portion sandwiched between both mold plates to form a resin molded product. Special pin 7 is "0", "4",
It is a pin that serves as a gate for sending the thermoplastic resin into the islands of letters and numbers having islands surrounded by lines such as "6", "8", "9", "#", and surrounds the islands. The portion corresponding to the line is projected to the middle of 6, and the resin can pass through the gap formed by the tip of the pin 7 and the fixed-side mold plate 1. A movable plate 8 is connected to the special pin 7 and is pressed against the movable side mold plate when the thermoplastic resin is injected.

The thermoplastic resin is emptied from the pin gate 2 into the cavity portion 6.
Inject and cool. When the mold is opened, first the pin gate portion 2 is pulled out, and then the space between the mold plate 1 and the mold plate 5 is opened, but the key top formed of thermoplastic resin in the space 6 is adjusted by adjusting the draft angle and the like. Leave the shape attached to template 1. After that, the fixed-side mold plate 1 is replaced with the fixed-side mold plate 2 and the molding is performed by the second mold. FIG. 2 shows a structural example of the second mold. 9 is a fixed-side mold plate of the second mold, and 10
Is the pin gate. From the pin gate 10 to the TPE in the gap between the template 5, the template 9 and the solidified key top 6 '.
The E composition is injected. Prior to injection, the special pin 7 is lowered from the original position and the pin tip is at the same height as the top surface of the key top. By doing so, the space formed by the special pin 7 is also filled with the TPEE composition. TP
The EE composition fills the switch portion 11, the skirt portion 12, and the base portion 13, and also fills the numeral and numeral portions 3, 4 to form the KBSW basic structure.

The skirt portion 12 has a thickness of 0.1 to 0.25.
It is preferable that the width is about 1 mm and the tilt angle is about 45 degrees in terms of usability. After cooling, the ejector pin 15 is driven to release the molded product. An example of the molded product is shown in FIG. If a conductive ink containing carbon is printed on the back surface portion 14 of the switch portion 11 of this molded product, a keytop-integrated keyboard switch with a display can be obtained. FIG. 4 shows an example of characters on the upper surface of the key top of the molded product. Numbers having island areas, for example, "4" and "5" are displayed by the special pin 7.

[0011]

According to the present invention, by using a two-color molding machine using a TPEE composition and a thermoplastic resin as raw materials,
In the process, all molding except the conductive printing process can be performed. Therefore, the process can be simplified and the cost can be greatly reduced. According to the present invention, since the display of the key is made by two-color molding, the display does not disappear even when the key is used frequently or in a place where the environment is bad. According to the present invention, the contact feeling of the letters and numbers is soft and non-slip, and it is less likely to make a mistake in pressing. In addition, since the contact feeling of the letters and numbers is different from that of the ground portion, it is possible to supply an easy-to-use SW to a blind person or a visually impaired person.

[0012]

【Example】

Example 1 90 parts by weight of TPEE "PIBIFLEX 35M (manufactured by Enichem Polymeri)", 10 parts by weight of acrylonitrile butadiene rubber "JSR / NBR230S" (manufactured by Nippon Synthetic Rubber Co., Ltd.), and polyorganosiloxane "silicone oil SH ( Toray Dow Corning Silicone Co., Ltd.) "by 0.05 parts by weight using a Henschel mixer, and then kneaded by a twin-screw extruder at a heating temperature of 200 ° C. During the kneading, a plasticizer" 20 parts by weight of "Sanso Sizer DUP (manufactured by Shin-Nippon Science Co., Ltd.)" was added to produce a pellet-shaped molding material. This TPEE
The JISA hardness of the composition was 85.

The above-mentioned "PIBIFLEX 35
"M" is a multi-block polymer in which a plurality of hard segments of polybutylene terephthalate, which is an aromatic polyester, and a plurality of soft segments of polytetramethylene glycol, which is a polyether, are alternately linked, and has a molecular weight of 100,000 to 150,000 and a softening point of 175 ° C,
The JIS A hardness is 93. For thermoplastics,
A black grade of polycarbonate resin "Taflon R1700 (made by Idemitsu Petrochemical Co., Ltd.)" was used.

As the first mold and the second mold, the molds shown in FIGS. 1 and 2 were used. The key top has a rectangular shape of 20 mm × 25 mm, a thickness of 3 mm, a numeral is displayed, and a line width is 1 mm. The total height from the top of the key top to the bottom of the base is 7 mm,
The thickness of the base is 1 mm and the thickness of the skirt is 0.15 m.
m, the width was 1.2 mm, and the mounting angle was 45 degrees. The height of the gap between the back surface of the switch and the bottom surface of the base portion was 1 mm (that is, the stroke was 1 mm). The number of the tips of the special pins 7 for injecting PC into the islands within the characters such as the numbers “4” and “6” was changed depending on the numbers, but it was provided at one or two places. Pin tip of special pin and mold plate 1 when molding with 1st mold
The gap formed by the above was 1.5 mm. Using a DC120 type core rotary type two-color molding machine, a molded product was obtained as designed. The contact feeling of the key top of the molded product was slightly slimy in the number part, which was preferable. There was a feeling that the number part was slightly shrunk compared to the ground part, and there was no mark of the special pin because of that. Commercially available conductive printing ink containing carbon and silver powder was screen-printed on the back surface of the key and baked at a predetermined temperature to form a keytop-integrated KBSW. The pressing pressure was 135g on average, but 1
There was no change after, 000,000 times of keystrokes. Moreover, when the contact resistance was measured by pressing SW at 250 g on the gold-plated comb-shaped contact substrate used for ordinary telephones, the average was 50 ohms, but the contact resistance after tapping 1 million times was 60 ohms and 20%. It was only an increase.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a structure of a first mold.

FIG. 2 is a schematic diagram showing the structure of a second mold.

FIG. 3 is a schematic view of a keyboard switch manufactured in an example.

FIG. 4 is an example showing a character portion on the upper surface of a key top of a keyboard molded product.

[Explanation of symbols]

 1, 9 Fixed side template 2, 10 Pin gate 3 Key top character part (line surrounding island) 4 Key top character part 5 Movable side template 6, 6'Key top (non-character part) 7 Special pin 8 Movable plate 11 Switch part (pressing part) 12 Skirt part 13 Board part 15 Ejector pin 16 Part where special pin is inserted

Claims (3)

[Claims] 1. A movable side mold plate having the same or the same shape is used for the first mold and the second mold, and in the first mold, a thermoplastic resin is injected from a fixed side mold plate by a plurality of pin gates to form a key. A pin gate in which a top group is molded, and thereafter, the fixed side template is replaced with a second mold while each key top molded article is attached to the movable side template, and the thermoplastic elastomer composition is provided on the back surface of each key. It is ejected from each key top and heat-bonded to the back of each key top to integrate each key and the thickness of the periphery of each key is 0.1 to 0.1 mm.
A push-button switch is obtained by enclosing a skirt with a thin skirt of 0.25 mm and connecting the whole with the periphery of the skirt as a plate. A method for producing a keyboard switch integrated with a keytop, characterized in that a composition containing an aromatic polyester polymer as a main component and having a hardness of JIS A 75 to 95 degrees is used for the thermoplastic elastomer composition. 2. A key top is formed so that the thermoplastic resin does not enter the character portion by forming a character-shaped projection in the portion of the fixed mold plate of the first die that contacts the back surface of each key. A patent characterized in that the thermoplastic elastomer composition enters into the character part in the second mold, and the thermoplastic elastomer composition displays characters and the like in the thermoplastic resin on the key top surface. A method for manufacturing a key top integrated keyboard switch according to claim 1. 3. The movable side template has a part corresponding to a character having an island region separated from the outside in a part of the display character in the part of the movable side template corresponding to the upper surface of each key. With the pin installed, the pin tip is slightly inserted from the height of the keytop top surface to the switch side when injecting with the first die, and the pin tip is flush with the top surface of the keytop when injecting with the second die. A method for manufacturing a keytop-integrated type keyboard switch according to claim 2, characterized in that a mechanism capable of returning is provided. [0001]