JP2001093707A - Pressure-sensitive conductive composition and pressure- sensitive conducting sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure-sensitive conductive composition, where increase of resistance caused by increase of temperature can be compensated and temperature dependence on pressure-sensing characteristic is reduced. SOLUTION: This pressure-sensitive conductive component is composed of three components where organic polymer as matrix, conductive particles, and electric resistance powder which has NTC characteristic and electric resistivity of 100 Ωcm to 500 MΩ cm which is measured by applying a pressure of 5 kgf/cm2 at 25 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive conductive composition and a pressure-sensitive conductive sensor having a property of changing an electric resistance value by applying a pressure.

[0002]

2. Description of the Related Art Pressure-sensitive conductive compositions having the property of changing the electric resistance value by applying pressure are widely known. For example, Japanese Patent Publication No. 56-187 discloses a pressure-sensitive conductive elastic composition composed of a base material made of an organic flexible material and artificial graphite particles whose corners are dropped. JP-A-59-98164 discloses a pressure-sensitive conductive silicone rubber composition containing 100 to 2000 parts by weight of conductive metal particles surface-treated with a platinum compound per 100 parts by weight of a silicone rubber composition. Is disclosed.

[0003] Further, an organic polymer as a matrix,
A pressure-sensitive conductive composition comprising at least three components of conductive particles and electric resistance powder is described in, for example, JP-A No. 2-18.
No. 6604 discloses a pressure-sensitive resistance-change-type conductive composition containing an organic polymer material, a conductive material, a semiconductor material having an electrical conductivity of 1/100 or less of the conductive material, and an insulating material. It is known.

Further, Japanese Patent Publication No. 7-87123 discloses a binder 100 made of at least one resin selected from vinyl chloride resin, vinyl acetate resin, vinyl chloride, vinyl acetate copolymer resin, and modified resins thereof. 30 to 180 parts by weight of flaky graphite with respect to parts by weight, and 50 or more of one or more materials selected from a semiconductor material and an insulating material having an electrical conductivity of 1/100 or less of the graphite.
There is a pressure-sensitive resistance-change-type conductive and film-forming composition used as a switch element containing about 340 parts by weight and an organic solvent.

Also, Japanese Patent Application No. Hei 10-640 filed by the present applicant.
No. 11 discloses a green compact obtained by pressing 50 to 200 parts by weight of carbon particles having an average particle diameter of 2 to 50 μm with respect to 100 parts by weight of liquid rubber at 4.9 × 10 ⁵ Pa (5 kg / cm ² ). Has a specific electrical resistance of 10Ω · cm to 200MΩ · cm
And 0.1 to 5 parts by weight of a high-resistance powder having an average particle diameter of 0.05 μm to 5 μm. Examples to the resistance value ratio under no pressure time and the maximum load applied 10 ⁵ or more by incorporating a high-resistance powder (600Ω~> 100MΩ) is disclosed.

[0006]

However, a conventional pressure-sensitive conductive sensor using a pressure-sensitive conductive composition has a large temperature-dependent pressure-sensitive characteristic. For example, a resistance value of 5 to 20 ° C. to 60 ° C.
The handling was difficult due to the change in the order of magnitude. In this conventional pressure-sensitive conductive sensor, when the temperature decreases, the resistance value decreases and the change range of the resistance value from no load to the maximum load decreases, and conversely, as the temperature increases, the resistance value increases and the resistance value increases from no load to the maximum load. Becomes larger. This is due to expansion and contraction of the matrix polymer, which is a dispersion medium of the conductor, due to heat. That is, when the temperature increases, the matrix polymer expands, the interval between the conductors increases, and the electric resistance increases. On the other hand, when the temperature decreases, the opposite phenomenon occurs and the electric resistance decreases.

[0007]

The present invention provides a pressure-sensitive conductive composition having NTC characteristics (Negative Temperature Coefficient:
By blending an electric resistance powder having an electric resistance value that decreases as the temperature increases, the increase in resistance value due to an increase in temperature is compensated for, and the temperature dependence of pressure-sensitive characteristics is reduced. .

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a pressure-sensitive conductive composition comprising at least three components of an organic polymer as a matrix, conductive particles, and an electric resistance powder. It is a pressure-sensitive conductive composition characterized by satisfying the conditions. (1) The compounding amount is 0.1 to 100 parts by weight of the organic polymer.
10 parts by weight. (2) The specific electric resistance measured under a pressure of 5 kgf / cm ² at 25 ° C. is 100 Ω · cm to 500 MΩ · c.
m. (3) Having NTC characteristics.

Further, there is provided a pressure-sensitive conductive composition wherein the organic polymer is an addition type liquid silicone rubber. Further, a pressure-sensitive conductive composition comprising at least three components of an organic polymer as a matrix, conductive particles, and electric resistance powder, wherein the electric resistance powder satisfies the above three conditions, A pressure-sensitive conductive sensor provided above.

The electric resistance powder used in the pressure-sensitive conductive composition of the present invention is a powder having an NTC characteristic that a resistance value changes with temperature (negative temperature coefficient). Further, 0.1 parts by weight of the organic polymer as the matrix is 0.1 part by weight.
It is preferable to mix 10 parts by weight to 10 parts by weight. When the amount is less than 0.1 part by weight, the effect of NTC characteristics is not exhibited due to a small amount of compounding. Absent.

Further, at 25 ° C., 5 kgf / cm ²
The specific electrical resistance measured under pressure of 100Ω · cm ~
It is preferably 500 MΩ · cm. If it is less than 100 Ω · cm, the effect of changing the resistance value change ratio is not sufficient, and if it is more than 500 MΩ · cm, the pressure-sensitive characteristics are not smooth, which is not preferable. A more preferable range of the compounding amount and the specific electric resistance value depends on the particle size of the electric resistance powder. For example, when the particle size is 0.01 μm to 2 μm, the compounding amount is 0.2.
Parts by weight to 3 parts by weight are preferable, and the specific electric resistance value is 100 k.
Ω · cm to 100 MΩ · cm is preferable.

The organic polymer of the present invention comprises SBR, NBR,
Rubber-like elastic materials such as BR, CR, urethane rubber, silicone rubber, vinyl chloride resin, vinyl acetate resin and soft synthetic resins can be used, but they have cold resistance and heat resistance, and are applicable to pressure-sensitive conductive materials. The addition type liquid silicone rubber is most preferable because it can be used as a composition and the crosslinking curing time is short. The conductive particles used in the present invention,
Graphite particles, metal particles, and the like can be used, but glassy carbon particles are most preferable in consideration of high hardness, high wear resistance, excellent chemical stability, and the like.

Now, the present invention will be described in further detail with reference to Examples. The pressure-sensitive conductive sensors prepared in Examples and Comparative Examples are wound with a high-rigidity film in order to reduce both the hysteresis and the temperature dependency of the pressure-sensitive characteristics at the time of pressurization and decompression. It is not limited to this mode.

Example 1 An NTC powder was produced by the following method. Purity 9
4 g of 9.9% manganese carbonate and 1 g of cobalt oxide having a purity of 99.95% are placed in an alumina crucible, heated and maintained at 400 ° C. for 2 hours in an electric furnace in an air atmosphere, and then heated to 1200 ° C. and maintained for 2 hours. . After slow cooling, the calcined powder taken out of the furnace was ground and then sedimented and classified in methanol to obtain an NTC powder having a particle diameter of 2 μm or less.

When a pressure of 5 kgf / cm ² was applied to the produced NTC powder and the electric resistance and its temperature dependency were measured, the electric resistance was 30 MΩ · cm at 26 ° C.
The temperature dependency was 5700 as a B constant value (commonly used in NTC thermistor characteristic display) (26 ° C .: 30 M).
Ω, 40 ° C .: 14 MΩ, 60 ° C .: 4.3 MΩ).

A pressure-sensitive conductive composition was prepared in the following manner.
Addition type liquid silicone rubber (SE1740, manufactured by Toray Dow Corning Silicone Co., Ltd.) was used as the matrix.
00 parts by weight (20 g) and 120 parts by weight of spherical glassy carbon particles (ICB1020 manufactured by Nippon Carbon Co., Ltd.) having an average particle diameter of 10 μm as conductive particles.
g), and 1 part by weight (0.2 g) of the NTC powder was mixed with stirring. This mixture was rolled with an ink roll (Otto He He, Germany) having a diameter of 35 mm and a gap adjusted to about 0.05 mm.
The product was passed twice through Model-35 (manufactured by Rmann) to obtain a pressure-sensitive conductive composition.

A pressure-sensitive conductive sensor was manufactured by the following method. FIG. 1 shows the configuration of the pressure-sensitive conductive sensor of the present embodiment.
The above pressure-sensitive conductive composition is placed at the center at 5.5 mm × 5.5 m.
After coating on a substrate 2 having a width of 9 mm and a length of 50 mm provided with an area of a comb-shaped electrode 1 having a size of m, and curing by heating at 100 ° C. for 1 hour, a semi-cylindrical shape having an arc-shaped cross section with a radius of curvature of 5 mm is formed. Shaving, and a thickness of 12.5 in the comb electrode area
15 mm wide polyimide film (Ube Industries, Ltd.)
(UPILEX 12.5S) 4 was wound to obtain a pressure-sensitive conductive sensor. In FIG. 2, the pressure-sensitive conductive sensor produced is pressed with a 5.5 mm-diameter hard plastic presser having a flat bottom, and the pressure-sensitive characteristics at 9 ° C., 26 ° C., 45 ° C., and 61 ° C. are measured. The resulting pressure-sensitive properties were shown.

[0017]

Comparative Example 1 A pressure-sensitive conductive composition was prepared by the following method.
Addition type liquid silicone rubber (SE1740, manufactured by Toray Dow Corning Silicone Co., Ltd.) was used as the matrix.
00 parts by weight (20 g) and an average particle diameter of 1 as conductive particles
120 parts by weight of 24 μm spherical glassy carbon particles (ICB1020 manufactured by Nippon Carbon Co., Ltd.)
g) and titanium oxide (A-1 manufactured by Ishihara Sangyo Co., Ltd.) in order to further increase the resistance value change range per unit additional load.
0.5) (0.1 g) was stirred and mixed. This mixture is adjusted to a gap of about 0.05 mm and has a diameter of 35 m.
m ink roll (Otto Hermann, Germany)
Model-35) twice to obtain a pressure-sensitive conductive composition. A pressure-sensitive conductive sensor was produced in the same manner as in Example 1. FIG. 3 shows the prepared pressure-sensitive conductive sensor with a diameter of 5.5 m.
m with a flat hard plastic presser.
The measured pressure-sensitive characteristics at 27 ° C., 27 ° C., 44 ° C., and 62 ° C. showed the obtained pressure-sensitive characteristics.

[0018]

By using the pressure-sensitive conductive composition containing the electric resistance powder having NTC characteristics of the present invention, the temperature dependence of the pressure-sensitive property of the pressure-sensitive conductive sensor using the pressure-sensitive conductive composition is improved. Sex can be made extremely small. The pressure-sensitive conductive composition of the present invention can be widely used for input devices of multimedia equipment, industrial pressure sensors, and the like.

[Brief description of the drawings]

FIG. 1 (a) A pressure-sensitive conductive sensor using the pressure-sensitive conductive composition of Example 1 (b) Comb-shaped electrode substrate

FIG. 2 is a pressure-sensitive characteristic of Example 1.

FIG. 3 shows pressure-sensitive characteristics of Comparative Example 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Comb-shaped electrode 2 Substrate 3 Pressure-sensitive conductive elastic body 4 Film

Claims (3)

[Claims] 1. A pressure-sensitive conductive composition comprising at least three components of an organic polymer as a matrix, conductive particles, and an electric resistance powder, wherein the electric resistance powder comprises the following 3
A pressure-sensitive conductive composition satisfying the conditions. (1) The compounding amount is 0.1 to 100 parts by weight of the organic polymer.
10 parts by weight. (2) The specific electric resistance measured under a pressure of 5 kgf / cm ² at 25 ° C. is 100 Ω · cm to 500 MΩ · c.
m. (3) Having NTC characteristics. 2. The pressure-sensitive conductive composition according to claim 1, wherein the organic polymer is an addition-type liquid silicone rubber. 3. A pressure-sensitive conductive sensor, wherein the pressure-sensitive conductive composition according to claim 1 is provided on an electrode.