JPS6160741A - Pressure-sensitive, reversely variable resistance electroconductive rubber and its production - Google Patents

Abstract

PURPOSE:To obtain the title inexpensive rubber easily in good efficiency, by laying a semiconductive rubber on a transfer film on which a pattern of an electroconductive material is printed and transferring the pattern to the rubber by heating. CONSTITUTION:A semiconductive rubber (A) of a volume resistivity of 10<4>-10<7> OMEGA.cm a JIS A hardness of 40-90 is obtained by kneading 100pts.wt. base (a) such as silicone rubber with 5-10pts.wt. carbon black (b) (e.g., Ketjen black) of an average particle diameter of 0.01-0.2mu and a vulcaniziang agent (c). An electroconductive material (B) of a volume resistivity of 1-10<2>OMEGA.cm is obtained by kneading 100pts.wt. component (a) with 20-50pts.wt. components (b) and (c). Material (B) is applied to the surface of a transfer film of good releasability such as a PE film by screen printing to form a pattern of a height of 5-10mu and a space <=2mm on the film. Rubber (A) is laid on said transfer film, the pattern is transferred to rubber (A) by application of heat and pressure, and the transfer film is peeled off to obtain a pressure-sensitive, reversely vari able resistance electroconductive rubber.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a pressure-sensitive reverse variable resistance conductive comb and a method for manufacturing the same. The present invention relates to a pressure-sensitive reverse variable resistance conductive rubber in which the resistance changes depending on the applied pressure in a conductive rubber exhibiting resistance or insulation, and a method for producing the pressure-sensitive reverse variable resistance conductive rubber. .

[Background of the invention]

As a pressure-sensitive conductive rubber that exhibits insulating properties when no pressure is applied and exhibits conductivity when pressurized, there is a known pressure-sensitive conductive rubber that is formed into a desired shape and has a micropattern of an insulating material formed on the surface of the conductive rubber.

This pressure-sensitive conductive rubber is made by forming patterns 2 made of an insulating material at intervals on a semi-conductive rubber 1, as shown in FIG. 1 (al). is pressed by the electrode 3 with a pressure P (see Fig. 1 (bl)).
The pattern 2 is buried in the semiconductive rubber 1 and deformed and flattened, so that the semiconductive rubber 1 becomes the electrode 3.
(See Figure 1 (C)).Since the electrode 3'' is also bonded to the back side of this pressure-sensitive conductive rubber, a current will flow between the electrodes 3 and 3'. .

The pressure-sensitive conductive rubber described above is a so-called on-off switch that exhibits insulation when no pressure is applied and conductivity when pressure is applied, and has the opposite function, that is, when no pressure is applied. Pressure-sensitive conductive rubber, which exhibits conductivity or low resistance when pressure is applied, and insulating or high resistance when pressure is applied, has not been manufactured previously, and furthermore, it gradually becomes more insulating than conductive in proportion to the pressure load. There was also no pressure-sensitive reverse variable resistance conductive rubber that would increase the resistance.

Further, in the pressure-sensitive conductive rubber as described above, the pattern 2 made of the insulating material is formed by forming an insulating material photoresist on the semiconductive rubber 1 and exposing this photoresist to a predetermined pattern using a mercury lamp or the like. It is manufactured by etching and forming a pattern 2 on a semiconductive rubber 1.

However, this method of forming the pattern 2 by photoetching requires pretreatment such as oxygen plasma treatment to improve the adhesion between the semiconductive rubber 1 and the insulating material pattern 2. At the same time, it has the disadvantage that it requires various difficult-to-control processes, such as the process of forming a photoresist, the process of covering with a patterned mask and exposing it to light, and the chemical etching of unexposed areas.
This method has the disadvantage of being expensive to manufacture and not suitable for mass production.

[Summary of the invention]

The present invention has been made in view of the above-mentioned points, and provides a variable resistance pressure-sensitive conductive rubber whose resistance increases depending on the pressure load condition, which has not existed in the past, that is, a pressure-sensitive reverse variable resistance conductive rubber. Another object of the present invention is to provide a method for easily and inexpensively manufacturing such a pressure-sensitive reverse variable resistance conductive rubber.

Therefore, the pressure-sensitive reverse variable resistance conductive rubber according to the present invention is obtained by forming a conductive material pattern on a semiconductive rubber made semiconductive by adding carbon black to make it conductive. This is a characteristic feature.

In addition, the method for producing the pressure-sensitive reverse variable resistance conductive rubber according to the present invention involves screen printing a pattern of a conductive material made conductive by adding carbon black to a transfer film having good mold releasability. The printed transfer film is laminated on a semiconductive rubber made semiconductive by adding carbon black, and the pattern is transferred onto the semiconductive rubber by heating, and then the transfer film is peeled off. This is a characteristic feature.

According to the present invention, a semiconductive rubber added with carbon black and a conductive material are used, and a pattern of the conductive material is formed on the semiconductive rubber. It has the advantage of being a variable resistance conductive rubber.

Further, according to the method for producing a pressure-sensitive reverse variable resistance conductive rubber according to the present invention, a predetermined pattern is screen printed on a transfer film, and this pattern is laminated on a semiconductive rubber and heated, or a pressure is applied together with heating. Since the transfer is carried out under load, a conductive material pattern can be easily and inexpensively formed on the semiconductive rubber. Furthermore, since the pattern is thermally transferred from the transfer film, the adhesiveness between the semiconductive rubber and the conductive material pattern is improved, and there is an advantage that a pressure-sensitive reverse variable resistance conductive rubber that can be used practically without any problems can be produced.

[Detailed description of the invention]

The present invention will be explained in more detail.

The base material of the semiconductive rubber used in the present invention may be any material as long as it has elasticity.
For example, silicone rubber, NBI? .

Polybutadiene, natural rubber, polyisoprene, 5BR1
It can be neorene, El'DH, urethane rubber, etc.

As a conductive material for imparting semiconductivity to such a rubber material, carbon black powder such as Ketjen blank or acetylene blank is used.

Further, the amount of carbon black powder added is preferably 5 to 10 parts by weight per 100 parts by weight of rubber.

If it is less than 5 parts by weight, the desired conductivity cannot be obtained;
On the other hand, if it exceeds 10 parts by weight, the conductivity becomes too good and it can no longer be called semiconductive.

The average particle size of the carbon black powder is preferably 0.
．． 0.01 to 0.2 μm, particularly preferably 0.01 to 0.05 μm. If the average particle size is less than 0.01 μm, the desired conductivity cannot be obtained even if a predetermined amount of carbon black powder is added, and if it exceeds 0.2 m,
This is because it significantly enhances the basic performance of the rubber material.

The volume resistivity of such semiconductive rubber is preferably 1
04-10'Ω country. If it is smaller than 104Ω, the difference in volume resistivity with the conductive rubber will be too small, making it difficult for the conductive rubber of the pressure-sensitive reverse variable resistor to respond, and if it exceeds 107Ω, the difference in volume resistivity with the conductive rubber will be too small. This is because the difference is too large, making it difficult to use as a conductive rubber for pressure-sensitive reverse variable resistance.

Further, the hardness of this semiconductive rubber is preferably JIS
A hardness is preferably 40 to 90, hardness is 4
If it is less than 0, there is too much elasticity and the insulation properties will be exhibited with a small pressure, which is not practical.
If it exceeds this value, it will become too hard and will not exhibit insulation properties unless a large pressure load is applied, so it is not practical.

In the present invention, the conductive material formed on the semiconductive rubber as described above is one to which carbon black is added. Examples of base materials for such conductive materials include silicone rubber, NBR, polybutadiene, natural rubber, polyisoprene, and 58) 1 which are used as base materials for the above-mentioned semiconductive rubber.

Examples include neoprene, EPDM, and urethane rubber.

As the carbon black powder to be added, Ketjen blank, acetylene black, etc. can be used as described above, and the preferable particle size thereof is 0.01 as described above.
~0.2μm, particularly preferably 0°01~0.05μm
It is m. The average particle size is less than 0.01 μm,
This is because even if a predetermined amount of carbon black powder is added, the desired conductivity cannot be obtained, and if it exceeds 0.2 μm, the basic performance of the base material will be significantly impaired.

The aforementioned carbon black powder is preferably a rubber material 10
0 parts by weight, 20 to 50 parts by weight, particularly preferably 2 parts by weight.
The amount is 0 to 30 parts by weight. If it is less than 20 parts by weight, there is a risk that it will not exhibit electrical conductivity, while if it exceeds 50 parts by weight, the basic performance of the rubber material, such as tensile strength and compression set, will be impaired.

The volume resistivity of such a conductive material is preferably 1 to 1.
If the 0 volume resistivity, which is 02Ω, is smaller than 1Ω, the difference in volume resistivity with the semiconductive rubber becomes too large.
Pressure sensitive reverse variable resistance conductive rubber <<, also 102Ω
This is because if it is larger than this value, the resistivity of the body 82 with the semiconductive rubber becomes too small, making it difficult to create a pressure-sensitive reverse variable resistance.

Although a pattern is formed on the semiconductive rubber using the conductive material as described above, the shape of the semiconductive pattern is not fundamentally limited in the present invention. As shown in FIG. 2, it may be a pattern in which cubic insulating materials are formed at predetermined intervals.

The hardness of this pattern is preferably JIS A hardness,
A value of 40 to 90 is good; if it exceeds 90, it will become too hard and will not deform even when a large pressure load is applied, making it difficult to become a pressure-sensitive reverse variable resistance conductive rubber. If it is less than 40, it will be too soft. Therefore, it deforms with a small pressure load, making it difficult to become a pressure-sensitive reverse variable resistance conductive rubber.

Although the height of this pattern is basically not limited, it is preferably 5 to 10 us. If the height is less than 5 μm, the change in volume resistivity due to pressure will be steep, and if the height is less than 10 μm, If it exceeds this, a large amount of pressure will be required to increase the volume resistivity, making it impractical.

Furthermore, it is preferable that the spacing between the patterns is 2 or less. If it exceeds 211+, the change in volume resistivity due to pressure load will be too small to be practical.

The method for producing the pressure-sensitive reverse variable resistance conductive rubber according to the present invention is basically not limited, and conventional methods can be used effectively. However, in order to manufacture it cheaply and easily, it is preferable to use a method for manufacturing a pressure-sensitive reverse variable resistance conductive rubber according to the present invention, which will be described later.

According to the method for producing a pressure-sensitive reverse variable resistance conductive rubber according to the present invention, a predetermined pattern of conductive material is screen printed on a transfer film having good mold releasability.

The transfer film according to the present invention is not fundamentally limited as long as it has good mold release properties, and various types can be selected depending on the semiconductive rubber used, the type of ink for pattern printing, etc. As such a transfer film with good mold release properties, for example, polyester film, polyethylene film, paper coated with a silicone mold release agent, etc. can be effectively used.

Further, the conductive pattern ink to be printed on such a transfer film can also be determined functionally depending on the type of the base material of the conductive material, the type of the transfer film, etc. For example, silicone rubber, NBR, polybutadiene, natural rubber, polyisoprene, SBI+.

Conductive inks made by adding a predetermined amount of carbon black powder to neoprene, EPDM, urethane rubber, or rubber-based inks can be effectively used.

Next, as described above, a transfer film printed with a predetermined conductive pattern is laminated on the semiconductive rubber, and heat and pressure are applied to thermally transfer the predetermined pattern.

Next, a transfer film having a conductive material pattern screen-printed thereon is laminated on such semiconductive rubber, and heat transfer is performed.

Such a heat transfer process is for transferring the conductive material pattern formed on the transfer film to the semiconductive rubber, and the heat transfer conditions are basically as follows.

The heating temperature varies depending on the material of the subject, and is roughly selected based on the thermal softening point of the subject, but if the temperature is low, adhesion will be poor;
The specified pattern is not transferred.

Furthermore, if the temperature is too high, the pattern may collapse (ink bleed) or the transfer from the release film may deteriorate.

It is best to select an appropriate pressure depending on the shape and strength of the subject. If the pressure is too strong, the subject may be deformed or destroyed, and if it is too weak, only a partial transfer may be possible. This is because there are things that cannot be done.

The present invention will be explained in detail below.

Example Composition (1) having the following composition was kneaded with a roll to produce a semiconductive rubber.

Composition I Silicone rubber 10 parts by weight Ketjen blank (straight flea 0.03-0.1 pm)
10 ffli part vulcanizing agent
3 parts by weight of Composition (2) having the following composition was also kneaded with a roll to prepare a conductive rubber.

Composition ■ Silicone rubber 100 parts by weight Ketjenblack (diameter 0.03-0.1 μm) 3
0 M 3 parts by weight of part vulcanizing agent Next, composition (2) was screen printed on the polyester film as a transfer film in a pattern as shown in Figure 2 to form a conductive material pattern on the polyester film. .

A transfer film (polyester film) on which the conductive material pattern described above was printed was laminated on the semiconductive rubber (composition I), and after heat-forming at 170°C for 11 minutes, the transfer film was peeled off and a predetermined 4 A conductive material pattern was formed on semiconductive rubber.

FIG. 3 shows the change in volume resistivity of the test piece prepared in this manner due to the application of pressure.

As is clear from FIG. 3, the volume resistivity of the pressure-sensitive reverse variable resistance conductive rubber according to the present invention increases in accordance with the pressure load, and it is found that the pressure-sensitive reverse variable resistance conductive rubber exhibits good pressure-sensitive reverse variable resistance.

Furthermore, after applying pressure, the change in volume resistivity (A″) when the pressure is released is shown in Figure 4. It became clear that the hysteresis was small, not much different from the change (8°).

〔Effect of the invention〕

As explained above, according to the pressure-sensitive variable reverse resistance conductive rubber according to the present invention, a pattern of conductive material is provided on the semiconductive rubber, thereby providing a pressure-sensitive variable reverse resistance conductive rubber that has not been available in the past. be able to.

Furthermore, the pressure-sensitive reverse variable resistance conductive rubber according to the present invention exhibits good pressure-sensitive reverse variable resistance, and since inexpensive carbon black is used as the conductive powder, it has the advantage that it can be manufactured at low cost.

Further, according to the method for producing a pressure-sensitive variable resistance conductive rubber according to the present invention, since a conductive material pattern is basically formed by screen printing, it is possible to efficiently and easily produce a pressure-sensitive variable resistance conductive rubber. Manufacturable. Therefore, there is an advantage that the cost of the pressure-sensitive reverse variable resistance conductive rubber can be further significantly reduced.

Furthermore, since the conductive material pattern screen printed on the transfer film is transferred to the semiconductive rubber, there is an advantage that the peel strength of the conductive material pattern with the semiconductive rubber is extremely good.

[Brief explanation of the drawing]

Figure 1(a) is a perspective view showing pressure-sensitive conductive rubber, Figure 1(f)
b), Fig. 1(C) is a cross-sectional view showing the state when this pressure-sensitive conductive rubber is compressed, Fig. 2 is a front view showing an example of the conductive material pattern, and Fig. 3 is a cross-sectional view showing the state when this pressure-sensitive conductive rubber is compressed. Figure ff14 is a graph showing changes in volume resistivity due to pressure loading of the pressure-sensitive reverse variable resistance conductive rubber manufactured by the method, and FIG. 14 is a graph showing changes in volume resistivity after pressure is released. 1... Conductive rubber, 2... Insulating material pattern, 3
···electrode. Applicant's agent Masaki Amemiya Figure 1 (a) (b) (c) Procedural amendment (Hitomi dated 1139, 1939)

Claims (2)

[Claims] (1) A pressure-sensitive reverse variable resistance conductive rubber, characterized in that a pattern of conductive material made conductive by adding carbon black is formed on a semiconductive rubber made semiconductive by adding carbon black. (2) Screen-print a pattern of conductive material made conductive by adding carbon black to a transfer film with good mold releasability, and make the transfer film with the predetermined pattern printed on it by adding carbon black to make it semi-conductive. A method for producing a pressure-sensitive reverse variable resistance conductive rubber, which comprises laminating the conductive rubber on a semiconductive rubber, heating the pattern, transferring the pattern onto the semiconductive rubber, and then peeling off the transfer film.