JPS5998164A - Pressure-sensitive conductive silicone rubber composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Technique of the Invention 11 Field of J] The present invention relates to a pressure-sensitive conductive silicone rubber composition, and more specifically, a pressure-sensitive conductive silicone rubber composition that exhibits high resistance when no pressure is applied and low resistance when pressure is applied. The present invention is directed to conductive silicone rubber compositions.

[Problems in the Background Art] Conventionally, a pressure-sensitive resistor, which is made by dispersing conductive metal particles in a polymer elastomer and exhibits high resistance when no pressure is applied and low resistance when pressure is applied, has been used. It is generally used as a switch element in equipment.

In such a pressure-sensitive resistor, one of the important requirements for obtaining good pressure-sensitive conductivity is to uniformly disperse the conductive metal particles in the polymer elastomer.
There is.

In the method of uniformly dispersing conductive metal particles into a polymer elastomer, the surface of the conductive metal particles is treated with a rubber-like insulating binder beforehand, and then this is poured into a polymer elastomer. Dispersion and mixing (Unexamined Japanese Patent Publication No. 51-7
3300 (Japanese Patent Application Laid-open No. 125796/1983), or a method is known in which the material is treated with a silane cobbling agent and then dispersed and mixed in a polymeric 1-mer. According to these methods, the dispersion state of conductive metal particles is improved and oxidative deterioration of the particle surface is prevented, and C1 stability and durability are improved. This method was not necessarily satisfactory because the pressure was high, the effect was insufficient, and special operations such as pulverization were required after the conductive metal particles were processed.

Furthermore, magnetic metal particles are dispersed in the elastomer,
By applying a parallel magnetic field when forming into a sheet,
A method of increasing the resistance change due to pressurization and lowering the operating pressure is also known (Japanese Patent Application Laid-Open No. 53-897).
This method requires very special equipment because it is necessary to perform molding under a magnetic field, and has the disadvantage that it is not very versatile and can only be applied to sheet-shaped molded products.

[Object of the Invention] The present invention has been made to solve these conventional problems, and it is an object of the present invention to provide a novel pressure-sensitive conductive silicone rubber composition that eliminates all of the above-mentioned conventional disadvantages.

[Summary of the Invention] The above object is to create a silicone rubber composition in which 100 to 2000 parts by weight of conductive metal particles surface-treated with a -C1 platinum compound are blended with 100 parts by weight of the silicone rubber composition. achieved.

As the silicone rubber composition used in the present invention, either a room temperature curable silicone rubber or a heat vulcanizable silicone rubber can be freely selected depending on the purpose.

The conductive metal particles used in the present invention include single conductive metal particles such as known iron, copper, chromium, zinc, silver, nickel, cobalt, and aluminum, and conductive alloys made of two or more of these metal elements. Nickel, iron,
Single conductive metal particles such as copper are suitable. The particle diameter of these conductive metal particles is empirically 0.1 to 100 μm.
There is a suitable C, and the shape is not particularly limited, but
A spherical or star shape is preferable from the viewpoint of dispersibility.

The platinum compound that can be used in the present invention is not particularly limited, and any platinum compound that is soluble in an appropriate solvent and can be used as a catalyst for hydrosilylation reactions that are well known in the art. Any platinum compound can be used.

Specifically, examples include well-known chloroplatinic acid and its salts, platinum-olefin complexes as shown in Japanese Patent Publication No. 39-19259, and alcohols as shown in Reference Example 1 of Japanese Patent Publication No. 43-27853. and chloroplatinic acid hexahydrate (H2Pt 06 .6H20) (7) Reaction mixture, platinum-unsaturated group-containing siloxane complex as shown in Japanese Patent Publication No. 46-29731, Japanese Patent Publication No. 51-8926 A complex of vinylsiloxane and platinum as shown in Japanese Patent Publication No. 53-775, a complex of platinum and 1,3-divinyltetramethyldisi[1xane], a complex of triorganophosphine or bosphite and platinum as shown in Japanese Patent Publication No. 53-775, Examples include complexes of acetylacetonate platinum complex, 1-1 cyclic diene, and platinum. Among these platinum compounds, preferred in the present invention are DX, which have high solubility in various solvents and are easy to handle, complexes of unsaturated group-containing siloxane and platinum, and reaction mixtures of aliphatic alcohol and platinum. .

Further, the surface-treated conductive metal particles necessary for the pressure-sensitive conductive silicone rubber composition of the present invention are blended in an optimum amount of 100 to 2000 parts by weight per 100 parts of the silicone rubber composition. varies slightly depending on the particle size of the conductive metal particles, the type of metal, and the type of silicone rubber composition.

If the amount of conductive metal particles is less than 100 parts by weight, the conductivity during operation will generally decrease and an insulating state will result;
If the amount exceeds 0.00 parts by weight, the silicone rubber tends to become conductive even when no pressure is applied, and furthermore, the physical properties of the silicone rubber after curing deteriorate significantly, which is not preferable.

The pressure-sensitive conductive silicone rubber composition of the present invention has a predetermined amount of conductive metal particles subjected to C surface treatment using a platinum compound, so that the electrical resistance changes greatly between when pressurized and when not pressurized. , and has low operating pressure and high sensitivity.

Further, in the present invention, since a silicone rubber composition is used as the base rubber, a product can be obtained that has excellent weather resistance, heat resistance, and durability compared to the case where a general organic rubber is used. If necessary, it is also possible to dilute this composition with a solvent to adjust the viscosity to an appropriate level and print it directly onto the electrode by means such as screen printing to obtain a highly reliable and inexpensive pressure-sensitive conductive film. be.

``Examples of the Invention'' The present invention will be described in detail with Examples below, but the present invention is not limited to the following Examples, and the composition and other changes may be made within the scope of the gist of the present invention. can be changed arbitrarily. In addition, in the following explanation, all "divisions" are C.
Indicates "parts by weight".

[Synthesis of platinum compounds]

(1) Synthesis of a complex of unsaturated group-containing siloxane and platinum Tetramethyl-1,3,5,/- in a mixture of 1 to silium parts of chloroplatinic acid, 9 parts of ethyl alcohol, and 2.5 parts of sodium bicarbonate Tetravinylcyclotetrasiloxane was added and the mixture was heated to 70-75°C for 1 hour, then the temperature was raised to 95°C with nitrogen bubbling and heated to 2
Volatile components were removed under reduced pressure of 5 mm l-1a.

The thus obtained mixture of yellow liquid and solid was cooled and then filtered to obtain a pale yellow transparent liquid. Chemical analysis of this liquid showed that it contained 0.8 atoms of chlorine per atom of platinum, and 0.020 atoms of platinum per gram of the mixture.

(2) Synthesis of a complex between aliphatic alcohol and platinum.

In 10 parts of octyl alcohol, chloroplatinic acid hexahydrate (H
Dissolve 1 part of 2Ptcj2s 6H20) and heat the solution at 75-80°C for 2011 days at a pressure of 25 mm HrJ.
Heat this a! All of the water J5 and hydrogen chloride distilled into the tank was removed. The pressure was then reduced to 5 mm HQ and unreacted octyl alcohol was removed to obtain a dark reddish-brown liquid at 0.degree. The results of chemical analysis of this mixture were 3.5 atoms of chlorine for each atom of platinum, and 0.0 atoms of platinum for each atom of the mixture.
．． It was shown that it contained 35g.

[Production of conductive metal particles treated with platinum compound] [i] Platinum-
Production of siloxane complex treated nickel particles.

Nickel carbonyl 7) Average particle size obtained from X et al. 3-7 μm
For 100 parts of nickel particles, the above (1) C(f
1% by weight of vinylsiloxane-coordinated platinum complex
100 parts of xylene solution was added.

Next, this was stirred and heated using the 1-channel h method, and allowed to flow rapidly for 4 hours. Thereafter, the complex-treated powder thus obtained was filtered, washed, and heated at 150° C. for 2 hours to obtain platinum-siloxane complex-treated nickel particles.

The platinum-siloxane complex-treated nickel particles thus obtained were completely hydrophobized.

Examples 1 to 9 in which the above-mentioned nickel particles are shown below
Served.

[111 Preparation of nickel particles treated with platinum-aliphatic alcohol complex For 100 parts of nickel particles with an average particle diameter of 3 to 7 μm obtained from nickel carbonyl, 0.0 parts of the platinum-aliphatic alcohol complex obtained in the above (2) is added. 100 parts of an 8% xylene solution was added. The same operation as in [I] was added to this to obtain platinum-aliphatic alcohol complex-treated nickel particles. These nickel particles were used in Examples 10 to 12 shown below.

Examples 1 to 3 Additive silicone rubber (Toshiba Silicone ((TSE made in the US)
3221) 100 parts of platinum-siloxane complex-treated nickel particles [I] were mixed in the amounts shown in Table 1 to obtain a pressure-sensitive conductive silicone rubber composition. Further, this composition was diluted with C by adding xylene until it became screen-printable, thereby obtaining a paste-like pressure-sensitive conductive silicone rubber composition.

The paste-like composition thus obtained was
Print with a film thickness of about 100 μm in a pattern of l cm,
It was heated and cured at 150°C for 1 hour. Table 1 shows the electrical conductivity properties of the pressure-sensitive conductive film obtained under pressure and non-pressure conditions.

In addition, as Comparative Examples 1 to 3, compositions were prepared in the same manner as in Examples 1 to 3 except that the nickel particles were used untreated, and the compositions were printed at °C to obtain films. . The results of the comparative examples are shown in Table 1 together with the examples. Further, the pressure car resistance characteristics of Examples 1 to 3 and Comparative Examples 1 to 3 were as shown in the drawings.

(Hereafter, the margin) * Unit 2 parts (hereinafter, the margin) Examples 4 to 6 Heat-curable silicone rubber (XE53 manufactured by Toshiba Silicone ■)
13U) 100 parts of N] were mixed with platinum-siloxane complex-treated nickel particles as shown in Table 2, and 2,5-dimethyl-2,5-ditertiary was added as a vulcanizing agent. - Add 1 part of butyl peroxyhexane (50% paste) and
Press vulcanization was performed for a minute to obtain a sheet of a pressure-sensitive conductive silicone rubber composition having a thickness of 0.51 mm. Further, as Comparative Examples 4 to 6, flow sheets were obtained in the same manner as in Examples 4 to 6, except that the nickel particles were used without being treated.

Table 2 shows the electrical conductivity properties of the obtained pressure-sensitive conductive sheet under pressure and non-pressure.

*Unit 2 parts (hereinafter referred to as blank space) Examples 7 to 9 10,000 cP at 25°C with 10 ppm of platinum catalyst
Table 3 shows the platinum-siloxane complex-treated nickel particles obtained in (I) for 100 parts of a vinyl group-terminated dimethylpolysiloxane polymer having a viscosity of tm.
A base composition was obtained. To this, a cross-linking agent component, which is a branched organohydrodiemboric U xane having H(CH3) 2SiO+/2 units as a cross-linking agent and an addition reaction inhibitor blended at 0.5 times 4%, was added and mixed. A conductive silicone rubber composition was prepared. This product can be screen printed even without solvent, and continued in Examples 1 to 3.
After printing with the screen printing pattern using 'c, 1
It was heated and cured at 50° C. for 30 minutes to obtain a pressure-sensitive conductive film. Table 3 shows the electrical conductivity properties of the pressure-sensitive conductive film obtained under pressure and non-pressure.

(Left below) *Unit two-part Examples 10 to 12 Additive silicone rubber (Toshiba silicone (1 wooden TSE)
3221) 100 copies vs. r (II) -r4
The platinum-aliphatic alcohol complex-treated nickel particles were mixed in the amounts shown in Table 4 to obtain a pressure-sensitive conductive silicone rubber composition. This composition was further diluted by adding xylene to a viscosity that could be screen-printed to obtain a paste-like pressure-sensitive conductive silicone rubber composition. The thus obtained paste composition was then used in Example 1.
After printing with the screen printing pattern used in ~3,
It was cured by heating at 50"C for 11 hours. The electrical conductivity properties of the obtained pressure-sensitive conductive film under pressure and non-pressure are shown in Table 4.

In addition, as Comparative Examples 7 to 9, compositions were prepared in the same manner as in Examples 10 to 12, except that the nickel particles were used untreated, and the compositions were printed to form a film. =,
The results of the comparative examples are shown in Table 1 together with the examples.

(The following is a blank space) This treated powder was mixed with heat-curable silicone rubber (Toshiba Silicone (Tai-made XE5313U) in the amounts shown in Table 5, and press-vulcanized in the same manner as in Examples 4 to 6 to give a thickness of 0. A pressure-sensitive conductive silicone rubber sheet of .5cn was obtained. Also, as Comparative Examples 10 and 11,
Examples 4-6 except that the copper particles were used untreated.
A C vulcanized sheet was obtained in the same manner as above.

Table 5 shows the conductive properties of the pressure-sensitive conductive sheet obtained under pressure and without pressure.

(Margin below) *Unit double placement part

[Brief explanation of the drawing]

The drawing is a graph showing pressure-resistance value characteristics of an embodiment of the present invention. Representative Patent Attorney Suyama Sa - UekH￥-Ff <$/cm”>

Claims (1)

Scope of Claims: (1) 100 parts by weight of a silicone rubber composition contains 100 parts by weight of conductive metal particles whose surface has been treated with a platinum compound.
A pressure-sensitive conductive silicone rubber composition containing ~2000 parts by weight. (2) The pressure-sensitive conductive silicone rubber composition according to claim 1, wherein the silicone rubber composition is an air temperature curable silicone rubber. (3) The pressure-sensitive conductive silicone rubber composition according to claim 1, wherein the silicone rubber composition is a heat-curable silicone rubber. (,4) The pressure-sensitive conductive silicone rubber composition according to any one of claims '1 to 3, wherein the platinum compound is a complex of unsaturated group-containing siloxane and platinum. (5> The platinum compound is aliphatic alcohol and platinum chloride fl
(f) The pressure-sensitive conductive silicone rubber composition according to any one of claims 1 to 3, which is a reaction mixture with hexahydrate (1-12PtCβ6.6H20). (6) Conductive The pressure-sensitive conductive silicone rubber composition according to any one of claims 1 to 5, wherein the conductive metal particles are single conductive metal particles. (7) The conductive metal particles are at least The pressure-sensitive conductive silicone comb composition according to any one of claims 1 to 5, which is an alloy particle consisting of two types of metal elements. (8) The conductive metal particles have a particle size of 0.1. The pressure-sensitive conductive silicone rubber composition according to any one of claims 1 to 7, which is conductive metal particles of ~100 μm.