JPH04292670A - Electrically conductive ink composition and contact member - Google Patents

Abstract

PURPOSE:To obtain an electrically conductive ink composition excellent in adhesion to insulating silicone rubbers by blending a curable composition containing an organopolysiloxane, a crosslinking agent and electrically conductive carbon particles with a specific silazane compound. CONSTITUTION:An electrically conductive ink composition is obtained by blending (A) a curable composition containing (i) an organopolysiloxane having preferably >=2 alkenyl groups in one molecule and 100-200000cSt viscosity at 25 deg.C, (ii) a cross-linking agent which is an organohydrogenpolysiloxane having preferably >=2 hydrogen atoms bonded to silicon atom in one molecule and (iii) electrically conductive carbon particles with (B) a silazane compound expressed by the formula [R<1>, R<2> and R<3> are (un)substituted monofunctional hydrocarbon group]. The aforementioned ink composition is suitable for producing contact parts such as keyboards of electronic calculators, personal computers or telephone sets.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive ink composition and a contact member that can be suitably used for manufacturing contact members such as keyboards for office automation equipment such as calculators, personal computers, and telephones.

0002

[Prior Art and Problems to be Solved by the Invention] Silicone elastomer compositions can be made electrically conductive by adding and mixing metal particles such as silver and nickel and electrically conductive particles such as various forms of carbon black. can be granted. On the other hand, addition-curing adhesive compositions based on organopolysiloxanes having alkenyl groups such as vinyl groups bonded to silicon atoms have been known for some time, but these adhesive compositions still have insufficient adhesive properties. Moreover, there are problems in workability, especially in terms of viscosity.

For this reason, when manufacturing contact members such as keyboards for OA equipment such as calculators, personal computers, and telephones, conductive particles such as carbon black are traditionally contained within an insulator such as plastic or silicone rubber. A method of embedding and molding a cured conductive silicone rubber product, and a method of pasting a cured conductive silicone rubber product on the insulator have been adopted.

However, in these methods, it is necessary to first cure the conductive silicone rubber composition, and then manufacture contact parts (commonly known as "beans") by punching or the like, and embed them in the required parts of the insulator or attach them. If the number of contacts is large, such as a keyboard, or if the shape of the contacts is complex, such as a horseshoe or a rectangle with a hole in the center, it is very difficult to mold and there is a risk of defective products. The disadvantage is that the rate is high.

In contrast to such a method of embedding or pasting a cured conductive silicone rubber material in an insulator, Japanese Patent Publication No. 61-34982 discloses a method in which a non-conductive silicone rubber and a conductive silicone rubber blended with carbon black are integrated. We are proposing a method to do so. However, the method for this integration is to first cure a conductive silicone rubber composition containing carbon black, and then form a layer of a non-conductive addition-curing silicone rubber composition containing no carbon black on this cured layer. In this way, the conductive silicone rubber composition containing carbon black is first cured, and then the silicone rubber composition containing no carbon black is cured on this cured layer. Otherwise, it is difficult to integrate the two, so first a cured layer of non-conductive silicone rubber containing no carbon black is formed, and then a layer of a conductive silicone rubber composition containing carbon black is formed on it. , it is difficult to harden and integrate.

On the other hand, it is also conceivable to use a conductive ink composition instead of the conductive silicone rubber composition to form the contact portions of the keyboard. However, although the above-mentioned problems can be solved by using a conductive ink composition, a non-elastomeric conductive ink composition has the problem that cracks are likely to form in the contact portion after adhesion. In addition, in non-silicone elastomer-based conductive ink compositions, if the insulating base material is a cured silicone rubber material, elastomer-based conductive ink compositions may not adhere or have poor adhesive properties. Although silicone elastomer-based conductive ink compositions have good adhesion and adhesion to silicone rubber insulators, they tend to form organosilicone insulating layers on their surface layers, so high conductivity is required. In addition, when adding a solvent to reduce the viscosity of the composition, the binder silicone oil and conductive particles such as carbon black, Ni powder, and Ag-coated beads cannot be used for contact parts. If the bonding properties with the conductive particles are insufficient, the problem arises that the dispersion of the conductive particles becomes non-uniform, making it difficult to obtain uniform conductivity.

[0007] Therefore, it is desired to develop a silicone elastomer-based conductive ink composition that can be widely used in the production of contact members such as keyboards for various office automation equipment.

The present invention has been made in response to the above-mentioned needs, and has excellent adhesion and adhesion to various insulating base materials, especially insulating silicone rubber, and can be applied to these base materials without any restrictions on the curing order, resulting in productivity. An object of the present invention is to provide a conductive ink composition that can form a conductive pattern well and can therefore be suitably used for manufacturing contact members such as keyboards, and a contact member formed using the composition.

[0009]

[Means and Effects for Solving the Problems] As a result of extensive studies to achieve the above object, the present inventor has developed a curable composition containing an organopolysiloxane, a crosslinking agent, and conductive carbon particles using the following general formula. It has been found that the above-mentioned problems can be solved by blending the silazane compound shown in (1).

0010

[Chemical formula 2] (However, R1, R2, and R3 in the formula are each a substituted or unsubstituted monovalent hydrocarbon group.)

That is, the above (1) is added to a curable composition containing an organopolysiloxane, a crosslinking agent, and conductive carbon particles.
The conductive ink composition containing the silazane compound of the formula has excellent adhesion and adhesion to various insulating substrates, especially insulating silicone rubber, and the conductive carbon particles have the above-mentioned (
1) The surface is treated with the silazane compound of the formula to increase the bonding strength (binder strength) with the organopolysiloxane, and there is almost no decrease in viscosity, resulting in excellent dispersion stability after solvent dilution and abrasion resistance of the resulting cured product. , it also imparts appropriate thixotropic properties. Moreover, a silicone insulating layer is not formed on the surface layer of the cured product, and the composition of the present invention can be applied, for example, to a pre-cured insulating silicone rubber layer on a base material and cured, or By applying it to an uncured insulating silicone rubber layer and heating and curing both at the same time, it is possible to integrally form an insulating silicone rubber layer and a conductive silicone rubber layer. The inventors have discovered that the contact portions of keyboards and the like having various complex conductive patterns can be easily formed by employing the method, and have come to form the present invention.

Therefore, the present invention provides a conductive ink composition in which the silazane compound of general formula (1) is blended into a curable composition containing an organopolysiloxane, a crosslinking agent, and conductive carbon particles, and a conductive ink composition of the composition. A contact member having a conductive layer printed thereon is provided.

[0013] To explain the present invention in more detail below, the conductive ink composition of the present invention is produced by adding a specific silazane compound to a curable composition containing an organopolysiloxane, its crosslinking agent, and conductive carbon particles. This is what happens. In this case, as for the curable composition containing organopolysiloxane and its crosslinking agent, there is no restriction on the crosslinking method, and an organopolysiloxane component and its crosslinking agent component according to a known organopolysiloxane crosslinking method are used. However, when a contact member is manufactured by printing the conductive ink composition of the present invention by coating on an insulating material and curing it, surface tack may remain if a crosslinking method using an organic peroxide is adopted. Therefore, it is desirable to use a condensation reaction type or addition reaction type organopolysiloxane composition as the curable composition. In particular, in the case of a condensation reaction type, it is difficult to use a coating method such as screen printing because the surface film forms quickly. However, addition-curing type organopolysiloxane compositions do not have such disadvantages, so addition-curing organopolysiloxane compositions are suitable for manufacturing contact members such as keyboards. most preferred.

Such an addition-curing organopolysiloxane composition can be composed of known components, but the organopolysiloxane has at least two alkenyl groups in one molecule and has a viscosity at 25°C. It is preferable to use an organopolysiloxane of 100 to 200,000 cs, use an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms in one molecule as a crosslinking agent, and add platinum or a platinum compound catalyst.

To explain this addition-curable organopolysiloxane composition in more detail, the organopolysiloxane as the main ingredient has at least two alkenyl groups in one molecule and has a viscosity of 100 to 100°C at 25°C.
It is in the range of 200000cs, and in this case,
Examples of the alkenyl group include a vinyl group, an allyl group, a methacryl group, and a hexenyl group. Further, as organic groups other than alkenyl groups, monovalent hydrocarbon groups such as methyl, ethyl, propyl, trifluoropropyl, and phenyl groups can be included.

Specific examples of such organopolysiloxanes include the following.

[0017]

embedded image (In the above formula, p is 2 or 3, s, u and w are positive integers, and t, v and x are 0 or positive integers.)

00
18] The above-mentioned organopolysiloxane may be used alone or in combination of two
It may be a mixture of more than one species, or it may have a partially branched structure.

Furthermore, the organohydrogenpolysiloxane that acts as a crosslinking agent for the alkenyl group-containing organopolysiloxane has two or more silicon-bonded hydrogen atoms in one molecule; The siloxane may have a linear, branched, or cyclic structure, or may be a mixture thereof. Specifically, the following can be exemplified.

[0020]

[Chemical formula 4] (However, in the above formula, b, c, d, e, f, g, and i each represent 0 or a positive integer, and h represents an integer of 2 or more.)

[0021]

embedded image (However, in the above formula, R4 represents a hydrogen atom, a monovalent hydrocarbon group, or a triorganosiloxy group.)

[0022] The organohydrogenpolysiloxane may be used in an amount sufficient to supply 2 to 30 silicon-bonded hydrogen atoms per alkenyl group contained in the alkenyl group-containing organopolysiloxane. It is suitable and more preferably used in a ratio of 5 to 20.

The platinum or platinum compound catalyst added to both organopolysiloxanes is an addition reaction catalyst,
Acts as a curing accelerator. Examples of platinum or platinum compound catalysts include solid platinum supported on a carrier such as platinum black, alumina, or silica, chloroplatinic acid, alcohol-modified chloroplatinic acid, a complex of chloroplatinic acid and an olefin, and platinum and olefin. Examples include complexes with vinyl siloxane, but are not limited to these.

[0024] When using these catalysts, if they are solid catalysts, it is preferable to crush them finely in order to improve their dispersibility, or to use a carrier with a small particle size and a large specific surface area. Further, as for chloroplatinic acid or a complex of chloroplatinic acid and an olefin, it is desirable to use these by dissolving them in a solvent such as alcohol, ketone, ether or hydrocarbon.

[0025] The amount of these catalysts to be used can be adjusted to obtain a desired curing speed, but from an economic standpoint or to obtain a good cured product, it is preferable to use them in the following proportions. It is. That is, for those that are compatible with the siloxane component, such as alcohol-modified or vinyl siloxane-modified chloroplatinic acid, the amount is 0.1 to 100 ppm (in terms of platinum) based on the total amount of both organopolysiloxanes, and platinum black, etc. For solid catalysts, 20-500 ppm
(in terms of platinum).

[0026] The curable composition constituting the conductive ink composition of the present invention imparts conductivity to the ink composition.
Contains conductive carbon particles. As the conductive carbon particles, conventionally known ones that are normally used in conductive rubber compositions can be used, and specifically, Continex CF (manufactured by Continental Carbon Co., Ltd.), Vulcan C (manufactured by Cabot Corporation) can be used. Conductive furnace black (CF) such as ), super conductive furnace black (SCF) such as Continex SCF (manufactured by Continental Carbon), Vulcan SC (manufactured by Cabot), Asahi HS-500 (manufactured by Asahi Carbon), Vulcan XC -72
Extra Conductive Furnace Black (XCF) such as (manufactured by Cabot), Conductive Channel Black (CC) such as Kolux L (manufactured by Degussa)
, Denka Acetylene Black, Denka Black HS-100
Acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd.), 150
Examples include furnace black and channel black that are heat-treated at a high temperature of about 0° C., and Ketjenblack EC (manufactured by Akzo Corporation), which is a type of furnace black.

[0027] If the conductive carbon particles have a high sulfur content, when the conductive ink composition is an addition-curing organopolysiloxane composition, catalyst poisoning of the platinum or platinum compound catalyst may occur during long-term storage. Since this may deteriorate the curability of the composition, those with a relatively low sulfur content, particularly those based on acetylene black, are preferably used. Further, the specific surface area of the conductive carbon particles is appropriately selected and is not particularly limited, but those having a specific surface area of 2 to 1000 m2/g can be used.

The amount of the conductive carbon particles to be blended is appropriately selected and is not particularly limited, but is from 50 to 20 parts (parts by weight, hereinafter the same) based on 100 parts (parts by weight, hereinafter the same) of organopolysiloxane as the main ingredient.
It is preferably 0 parts, especially 80 to 150 parts. 50
If the silicone insulating layer is easily formed on the surface layer of the cured product in single-sided open curing systems (coating, screen printing, etc.), the surface resistance increases and the desired conductivity cannot be obtained. If it exceeds 200 parts, not only will the blending operation be difficult, but the siloxane content of the binder will decrease, resulting in a decrease in the abrasion properties of the cured product.
It may not be of practical use.

The conductive ink composition of the present invention contains a silazane compound as an essential component, which increases the binding force between the conductive carbon particles and the siloxane component and reduces the viscosity of the conductive ink composition. A compound represented by the following general formula (1) is used.

[0030]

[C6]

Here, R1, R2, R3 in formula (1)
are substituted or unsubstituted monovalent hydrocarbon groups, for example, monovalent hydrocarbon groups having 1 to 8 carbon atoms such as methyl group, ethyl group, vinyl group, phenyl group, trifluoropropyl group are preferable. . Furthermore, in an addition reaction type conductive ink composition, the presence of a vinyl group or a phenyl group in the silazane compound molecule of formula (1) further increases the binder force between the conductive carbon particles and the siloxane component, resulting in a conductive ink composition. Since the dispersion stability of the composition after dilution with a solvent and the abrasion resistance of the cured product can be improved, it is preferable that R1, R2, and R3 contain a vinyl group or a phenyl group.

Such a silazane compound of formula (1) is
It has a higher boiling point than the silazane compound represented by the following general formula (2), and also has a higher boiling point than the R4 3Si- group of the formula (2).
) In the formula, the -(R2SiR3)- group has high reactivity, so
It is very efficient when performing heat treatment with conductive carbon particles, and by using the silazane compound of formula (1), the thixotropic property of the conductive ink composition can be made suitable for screen printing. It is possible.

[0033]

[C7]

Specific examples of the silazane compound of the above formula (1) include compounds of the following formulas (3) to (6). Note that these silazane compounds can be used alone or in a mixture of two or more.

[0035]

[Image Omitted] The amount of the silazane compound of the above formula (1) is not particularly limited, but it is preferably selected depending on the amount of conductive carbon particles used and the specific surface area of the particles used. The amount is preferably 0.05 to 1 part by weight, more preferably 0.1 to 0.8 part by weight per 100 m2 of surface area. If the amount of the silazane compound is too large, not only is it economically disadvantageous, but the hardness of the rubber after curing may become too high or the reinforcing properties may decrease.

In addition to the above-mentioned components, the conductive ink composition of the present invention has one or more hydrogen atoms bonded to a silicon atom in one molecule, and further contains at least one of an alkoxy group and an epoxy group. It is preferable to blend an organopolysiloxane, and by blending this organopolysiloxane, it becomes possible to significantly improve adhesiveness. This organopolysiloxane acts to improve self-adhesion to the substrate to which the conductive ink composition is applied. As such organopolysiloxane, for example, Japanese Patent Publication No. 53-21026
Those having an alkoxysiloxy group disclosed in Japanese Patent Publication No. 53-13508, those having an epoxy-containing hydrocarbon group disclosed in Japanese Patent Publication No. 59-5219, and the alkoxysiloxy group and epoxy-containing hydrocarbon group disclosed in Japanese Patent Publication No. 59-5219. Those having the following are preferably used. More specifically,
Although not limited thereto, the following silicon compounds can be exemplified.

[0037]

embedded image These can also be used by increasing the degree of polymerization as appropriate depending on the purpose.

The above-mentioned organopolysiloxane is preferably used in an amount of 0.5 to 20 parts, particularly 1 to 10 parts, per 100 parts of the organopolysiloxane which is the main ingredient of the present invention.

Furthermore, in order to further improve the adhesive properties, compounds that enhance the adhesive effect, such as triallyl isocyanurate, triallyl trimellitate, and compounds modified with siloxane, may be added to the composition of the present invention. For example, one or more compounds having the following structures can be added.

[0040]

[Chemical formula 10]

[0041]

[Chemical formula 11]

[0042]

[Chemical formula 12]

[0043]

[Formula 13] Note that the amount of the above compound is as follows:
It is selected as appropriate and is not particularly limited, but it is preferably used in an amount of about 0.5 to 3 parts per 100 parts of the main organopolysiloxane.

[0044] In addition, in order to reinforce the strength of the cured product, the composition of the present invention is used in Japanese Patent Publication No. 38-26771 and Japanese Patent Publication No. 45-1989.
SiO2 unit disclosed in 9476 publication etc., CH
2=CH(R'2)-SiO0.5 unit and R'3-S
It is also possible to add an organopolysiloxane having a resin structure containing 0.5 units of iO (R' is a monovalent hydrocarbon group containing no unsaturated aliphatic group). The amount of the organopolysiloxane added is not particularly limited, but it is preferably used within a range of 30 parts or less based on 100 parts of the main organopolysiloxane. If the amount added exceeds 30 parts, not only will it be economically disadvantageous, but the rubber after curing may become hard and brittle.

Furthermore, for the purpose of controlling the curing speed of the composition, CH2 disclosed in Japanese Patent Publication No. 10947/1983
=CHR'Organopolysiloxane containing SiO units (R' is the same as R' above), U.S. Patent No. 3,445,42
The acetylene compound disclosed in U.S. Pat. No. 0, the ionic heavy metal compound disclosed in U.S. Pat. No. 3,532,649, and the like can be blended. Furthermore, a non-functional organosiloxane may be blended to improve the thermal shock resistance, flexibility, etc. of the cured product.

In addition, other optional components such as red red iron, black red iron, cerium oxide, etc., heat resistance improvers, flame retardant agents such as benzotriazole, zinc carbonate, and manganese carbonate, addition reaction control agents such as acetylene compounds, A foaming agent and the like may also be appropriately blended.

The conductive ink composition of the present invention preferably contains a solvent in order to adjust its viscosity and improve workability. As this solvent, when the composition is an addition-curing type, a volatile organic compound is suitably used; Almost all volatile organic compounds can be used, except for organic compounds that have an alkenyl group therein and disrupt the crosslinking balance. Specifically, volatile organic compounds include aromatic hydrocarbons such as benzene, toluene, xylene, and ethylenebenzene, aliphatic hydrocarbons such as hexane and octane, methyl acetate, ethyl acetate,
Esters such as isobutyl acetate, cyclic ethers such as furan and tetrahydrofuran, 1-propyl ether, n
-Ethers such as butyl ether and anisole; cyclic siloxanes such as octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane; chain siloxanes such as hexamethyldisiloxane, octamethyltrisiloxane and decamethyltetrasiloxane; Examples include chlorinated hydrocarbons such as chloroethylene and trichloroethylene, and fluorinated hydrocarbons such as octafluoropropane, and these solvents can be used alone or in a mixture of two or more. Among these, those having a boiling point of 130 to 200°C are preferably used, and in particular, a solvent containing 60% by weight or more of an aromatic solvent having a boiling point within the above range is suitable. The amount of the solvent to be used is appropriately selected, but it is preferably 50 to 2,000 parts, particularly 200 to 1,000 parts, based on 100 parts of the main organopolysiloxane.

The method for producing the ink composition of the present invention is not particularly limited, and it can be produced by kneading the above components and diluting with a solvent if necessary. A method of heat treatment in a kneader or the like together with siloxane and conductive carbon particles is preferably employed. In this case, the heating temperature is 50 to 200
The temperature is preferably 100 to 160°C, and water may be added to the system to further promote decomposition.

The conductive ink composition of the present invention can be applied to a substrate made of various electrically insulating resistors, cured, and used for manufacturing contact members such as keyboards, etc.
In this case, the electrical insulation resistor has a volume resistance of 1010
A material having a resistance of Ω·cm or more is preferably used. Further, its properties may be resin-like or elastic.Specifically, such electrical insulation resistors may be resin-like, such as ABS resin, PET resin, acrylic resin, polycarbonate resin, PBT. Examples include thermoplastic resins such as resins, PPS resins, and thermosetting resins such as epoxy resins and urethane resins. If the base material is hard resin,
Preferably, the conductive silicone rubber has a thickness of about 0.5 to 3 mm. If the thickness is less than 0.5 mm, not only will it feel bad when you press the key, but also a large amount of distortion will be applied to the interface between the board and the conductive silicone rubber, which may cause problems with adhesive durability. Furthermore, when coating a material with a thickness exceeding 3 mm, it may not only be industrially difficult but also economically disadvantageous. In addition to silicone rubber, various synthetic rubbers can be used as base materials for the elastic body, but especially in the production of keyboards, silicone rubber is preferably used from the viewpoint of electrical insulation and durability. The above-mentioned conductive ink composition is applied to the portion of the molded body that will become the contact point by an appropriate printing method such as a screen printing method to a thickness of an appropriate pattern (usually 5 to 50 mm).
Keyboards and the like can be made by applying the resin to a thickness of about 0 μm) and curing it. In this case, according to the composition of the present invention, an ink composition made of a conductive silicone rubber composition can be applied and cured to an insulating silicone rubber cured product that does not contain carbon black. Furthermore, after curing the insulating silicone rubber composition in advance and completing the curing through after-curing, the conductive ink composition of the present invention may be applied and cured by heating. The composition has good adhesion and adhesion with the insulating silicone rubber composition as a base material, and therefore, it can be applied onto a base material (primarily cured molded product) made of the insulating silicone rubber composition. After applying the conductive ink composition of the invention, it is also possible to after-cure both to perform curing and adhesion at the same time. When the conductive ink composition of the present invention is applied to the above substrate and cured by heating in this way,
A silicone rubber product in which a conductive silicone rubber layer and an insulating silicone rubber layer are integrated can be obtained. In addition, when forming a cured layer of the composition of the present invention on an insulating silicone rubber molded article, a primer can be used if necessary, although it is not essential.

[0050]

Effects of the Invention The conductive ink composition of the present invention has excellent adhesion and adhesion to various insulating substrates, especially insulating silicone rubber, has almost no decrease in viscosity, and is easily dispersed after dilution with a solvent. Excellent stability and abrasion resistance of the resulting cured product. Therefore, the composition of the present invention is suitably used for manufacturing contact members for keyboards, etc. In particular, contact members in which a conductive layer of the composition of the present invention is printed on an insulating silicone rubber molded body can be manufactured by screen printing, etc. By this method, contact parts such as keyboards having complicated conductive patterns can be easily formed. It is possible to obtain a contact member having a conductive contact layer with excellent adhesion even if it is coated on an insulating silicone rubber molded body that is only cured and cured at the same time, and is also excellent in terms of production efficiency. .

[0051]

[Examples] The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited to the following Examples. Note that all parts in each example are parts by weight. Also,
Viscosity indicates the value at 25°C.

[Example 1] 100 parts of a linear dimethylpolysiloxane having a viscosity of 1000 cs and having both ends capped with dimethylvinylsilyl groups, 10 parts of a silazane compound represented by the following formula (7), and 3 parts of water were added. 70 parts of acetylene black (manufactured by Denki Kagaku Co., Ltd.) having a specific surface area of 60 m 2 /g was added, and the mixture was heated and kneaded at 150 to 160° C. for 4 hours using a kneader.

[0053]

[Chemical formula 14]

After kneading, cool to room temperature and add 0.12% octanol solution of chloroplatinic acid (2% by weight as platinum).
1 part, 0.30 parts of ethynylcyclohexanol, and 1.8 parts of triallyl isocyanurate were added and kneaded. Next, this was mixed by three rolls, followed by 600 parts of mineral spirit and 13 parts of a crosslinking agent represented by the following formula (8).
Conductive ink composition I was prepared by adding and dissolving 5 parts and 6.0 parts of a compound represented by the following formula (9) as an adhesion aid into a mixed solution.

[0055]

[Chemical formula 15]

The conductive ink composition I obtained had a viscosity of 180 poise before curing, and was coated onto a PET film using a bar coater, air-dried for 30 minutes, and then heated at 120°C to 60°C.
Heating and curing for minutes, Rubber Association Standards (``Volume resistivity test method for conductive rubber and plastics'' 2301-
1969), the volume resistivity was 1.5 Ω·cm at a thickness of 0.02 mm.

[0057] This conductive ink composition I was also applied to the contact portion (diameter 3 mm) of a molded cured sheet of peroxide-curing silicone rubber KE951 (manufactured by Shin-Etsu Chemical Co., Ltd., JISA hardness 50) to a thickness of 50 μm by screen printing.
It was applied to. After air drying for 30 minutes, it was baked and hardened at 150° C. for 60 minutes. The cured layer of this conductive ink composition was formed with good adhesion to the molded cured sheet, and a keystroke test was conducted using this as a contact key, but no interfacial peeling was observed even after 500,000 times.

[Example 2] 100 parts of a linear dimethylpolysiloxane having a viscosity of 5000 cs and having both ends capped with dimethylvinylsilyl groups, 0.8 parts of a silazane compound represented by the following formula (10), and the following ( 11) 12.0 parts of the silazane compound represented by the formula, 4 parts of water, and a specific surface area of 30 m2/
100 parts of acetylene black (manufactured by Denki Kagaku Co., Ltd.) was added, mixed in a planetary mixer, heated and mixed at 160°C for 1 hour, and further mixed with nitrogen gas at 160°C for 1 hour to remove by-product ammonia. Removed gas.

[0059]

[Chemical formula 16]

[0060] This granular material was formed into a film using three rolls, and a petroleum-based hydrocarbon mixed solvent house (manufactured by Shell Chemical Co., Ltd.) was used.
700 parts were mixed and dissolved. Next, 0.1 part of an octanol solution of chloroplatinic acid (2% by weight as platinum content),
Add and mix 1.0 part of triallyl trimellitate and 0.2 part of ethynylcyclohexanol, and further 5.0 parts of a compound represented by the following formula (1) and 4.0 parts of a compound represented by the following formula (13). were added and mixed uniformly to prepare conductive ink composition II.

[0061]

[Chemical formula 17]

The obtained conductive ink composition II had a viscosity of 5.4 poise before curing, and as in Example 1, PET
When tested by coating and curing on a film, 1.
A volume resistivity of 2 Ω·cm was obtained.

[0063] This conductive ink composition II was also applied to liquid silicone rubber KE1940-40 (for addition injection molding).
A U-shaped contact portion (width 12 mm, length 5 mm, line width 2 mm) of a molded cured product manufactured by Shin-Etsu Chemical Co., Ltd. (JISA hardness 40) was coated to a thickness of 50 μm by screen printing. After air-drying for 30 minutes, heating and curing at 150°C for 60 minutes showed good adhesion, and a keystroke test was conducted using this as a contact key, but even after 100,000 keystrokes, the contact did not crack and the interface No peeling was observed.

Claims (4)

[Claims] 1. A conductive ink composition comprising a curable composition containing an organopolysiloxane, its crosslinking agent, and conductive carbon particles, and a silazane compound represented by the following general formula (1). thing. [Chemical formula 1] (However, R1, R2, and R3 in the formula are each a substituted or unsubstituted monovalent hydrocarbon group.) 2. The curable composition has at least two alkenyl groups in one molecule as an organopolysiloxane, and has a viscosity of 100 to 200,000 cs at 25°C.
Addition curing using an organopolysiloxane which is , an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms in one molecule as a crosslinking agent, and adding platinum or a platinum compound catalyst. The conductive ink composition of claim 1, which is a type organopolysiloxane composition. 3. A contact member comprising a conductive layer of the conductive ink composition according to claim 1 or 2 printed on an insulating silicone rubber molded body. 4. The uncured conductive ink composition of claim 2 is applied to the cured insulating silicone rubber molded article, and then heated and cured, so that the conductive layer made of the conductive silicone rubber becomes the insulating silicone rubber. The contact member according to claim 3, which is formed on a molded body.