JPH07331140A - Conductive silicone ink composition and its production - Google Patents

Abstract

PURPOSE:To obtain a conductive compsn. which is excellent in storage stability, adheres strongly to an adherend even after sulfurization, and has conductivity hardly changing with environmental temp. by compounding a specific polyorganosiloxane, a specific acetylene black, a specific silane, and a solvent. CONSTITUTION:This compsn.contains 100 pts.wt. polyorganosiloxane represented by the mean unit formula (wherein R is a monovalent hydrocarbon group; and a is 1.98-2.02), 10-100 pts.wt. carbon black produced by the exothermal decomposition of acetylene and having a chlorine liq. absorption of 12ml/5g or lower and an iodine adsorption of 50mg/g or lower, 100-1,000 pts.wt. solvent, and a silane or low-polymn.-degree polysiloxane having at least two moisture- hydrolyzable groups bonded to Si atoms through 0 or N atoms in an amt. of the hydrolyzable groups of 10-500 times that of silanol groups contained in the polyorganosiloxane and gives a coating film with a smooth surface.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention provides a conductive film which is excellent in storage stability, firmly adheres to an adherend after curing, has little change in conductivity due to environmental temperature changes, and has a smooth surface condition. -Related silicone ink composition.

[0002]

TECHNICAL BACKGROUND AND PROBLEMS OF THE INVENTION A liquid silicone composition prepared by using a curable polyorganosiloxane as a base polymer and diluting it with a solvent makes use of its excellent properties such as heat resistance and weather resistance for coating and marking. Widely used for various purposes. In particular, a conductive liquid silicone composition to which conductivity is imparted by blending conductive carbon black is used for applications such as a switching function and an electric circuit by utilizing its characteristics. However, the conventional conductive carbon black-containing liquid silicone composition is
The dispersibility or solubility of the conductive carbon black in a solvent is extremely poor, and since it is easily separated even after it is once dissolved, it is difficult to obtain a uniform and stable dispersion liquid or solution. In addition, there is a problem that the conductivity changes greatly depending on the ambient temperature, and there is a problem with the adhesiveness which is particularly important when using this as an ink.

As a technique for solving such a problem, Japanese Patent Application Laid-Open No. 4-300965 uses an addition-curable polyorganosiloxane as a base polymer, and uses a specific carbon black, a polyorganosiloxane having both alkenyl groups at both ends and polyorganosiloxane. A conductive liquid silicone composition containing a solvent has been proposed, but depending on the curing conditions of the ink, the adhesive strength may be insufficient, the coating film may swell, or pinholes may not be generated to obtain a smooth surface condition. There was a problem.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above problems, has excellent storage stability, firmly adheres to an adherend after curing, has little change in conductivity with environmental temperature changes, and has a smooth surface condition. It is an object of the present invention to provide a conductive silicone ink composition from which a coating film can be obtained.

[0005]

The present inventors have conducted extensive studies to achieve the above object, and as a result, use a specific condensation type polyorganosiloxane as a base polymer, and use a specific carbon black, a silane containing a hydrolyzable group or a low content The present inventors have found that a composition in which a specific degree of polymerization and a specific amount of a polysiloxane are mixed together to satisfy the above object, and have completed the present invention. That is, the present invention comprises the following components
A conductive silicone ink composition containing (A), (B), (C) and (D), and components (A) and (B) are mixed and heat treated, and component (C) is added and dispersed uniformly. This is a method for producing a conductive silicone ink, in which the component (D) is blended after the treatment. (A) is represented by the average unit formula R _a SiO _{(4-a) / 2} (wherein each R represents a substituted or unsubstituted monovalent hydrocarbon group, and a represents a number from 1.98 to 2.02). Polyorganosiloxane having at least two silanol groups in one molecule; 100 parts by weight (B) Amount of chlorine absorption produced by the acetylene exothermic decomposition method
Carbon black of 12 ml / 5 g or less and iodine adsorption amount of 50 mg / g or less; 10 to 100 parts by weight (C) solvent; 100 to 1000 parts by weight (D) Moisture bonded to silicon atom by oxygen atom or nitrogen atom in one molecule A silane or low-polymerization polysiloxane having at least two hydrolyzable groups (however, when the number of silanol groups in the component (A) is two in one molecule, at least three); included in the component (A) Amount of moisture-hydrolyzable groups corresponding to 10 to 500 times the amount of silanol groups The present invention will be described in detail below.

The polyorganosiloxane as the component (A) is mainly linear, but a part of the polyorganosiloxane may form a branched or three-dimensional structure, and a homopolymer, copolymer or It may be a mixture thereof. Examples of the substituted or unsubstituted monovalent hydrocarbon group R 1 of this polyorganosiloxane include an alkyl group such as methyl, ethyl and propyl; an alkenyl group such as vinyl, allyl and butenyl; an aryl such as phenyl, xenyl and naphthyl. Groups; cycloalkyl groups such as cyclohexyl; cycloalkenyl groups such as cyclohexenyl; aralkyl groups such as benzyl; alkylaryl groups such as tolyl and xylyl. The monovalent hydrocarbon group R directly bonded to the silicon atom of this polyorganosiloxane is preferably mainly a methyl group.

The component (B), carbon black, is one of the components that characterize the present invention and imparts excellent conductivity and moderately suppresses the viscosity of the ink composition. Produced chlorine absorption 12ml / 5g
Hereinafter, the iodine adsorption amount is 50 mg / g or less. The meanings of these quality characteristics are as follows. That is, the chlorine absorption amount specified in JIS K 1469 (acetylene black) is an index showing the degree of development of the structure "chain structure of carbon primary particles".
It is known that the amount of iodine adsorbed in 1474 "Test method for powdered activated carbon" is an index showing the strength of the structure. Here, when imparting conductivity to the rubber composition,
The more the structure is developed, that is, the chlorine absorption amount is larger and the structure is stronger, that is, the iodine adsorption amount is larger, the secondary contact probability of carbon increases, and the structure is destroyed by the stress of mixing or kneading. It is considered more desirable because it is hard to be done. However, in the case of silicone polymers, which are significantly softer than other organic polymers, the general idea does not apply, and a proper structure is required to enable uniform dispersion. That is, in order to impart good workability to the compound or composition and to impart good conductivity, the chlorine absorption amount of acetylene black is 12
It is necessary that the amount is not more than ml / 5g and the iodine adsorption amount is not more than 50mg / g. When any of the values exceeds the above values, good workability and good conductivity cannot be imparted. Absent. If the blending amount of this component (B) is too small, good conductivity cannot be imparted, and if it is too large, the mechanical properties of the conductive coating film obtained by curing this will decrease, so the component ( A) Use in the range of 10 to 100 parts by weight with respect to 100 parts by weight.

The solvent of the component (C) is for obtaining good workability as an ink and includes toluene, xylene, cyclohexane, n-hexane, n-heptane, n-octane, naphtha, mineral spirits and petroleum benzine. Hydrocarbon solvent; halogenated hydrocarbon solvent such as chloroform, carbon tetrachloride, trichloroethylene, perchloroethylene, 1,1,1-trichloroethane, perfluoropropane; propyl ether, n-butyl ether, anisole, tetrahydrofuran, ethylene glycol , Ether solvents such as diethyl ether; ester solvents such as ethyl acetate, butyl acetate, amyl acetate; acetone;
Ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and acetophenone; alcohol solvents such as methanol, ethanol, isopropanol, butanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, ethylene glycol, propylene glycol; hexamethyldi Chain-like siloxane solvents such as siloxane, tetramethyldiphenyldisiloxane, octamethyltrisiloxane, decamethyltetrasiloxane; hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, heptamethylphenylcyclotetrasiloxane, heptamethylvinylcyclotetrasiloxane , A cyclic siloxane-based solvent such as decamethylcyclopentasiloxane. This ingredient
For (C), these solvents may be used alone or in combination of two or more kinds. When the amount of this component (C) is too small, it is difficult to obtain good workability as an ink,
If it is too large, a sufficient film thickness cannot be obtained as a conductive coating film, so it is used in the range of 100 to 1000 parts by weight per 100 parts by weight of component (A).

At least two moisture-hydrolyzable groups bonded to a silicon atom by an oxygen atom or a nitrogen atom in one molecule of the component (D) (provided that two silanol groups in the component (A) are two per molecule). In the case of, at least 3) silane or low polymerization degree polysiloxane is
It has the function of hardening (A) to (C) and the function of imparting adhesiveness. In the component (D), examples of the moisture-hydrolyzable group bonded to a silicon atom by an oxygen atom include an alkoxy group, a vinyloxy group, an N, N-diorganoaminoxy group and a ketoxime group, and a silicon atom by a nitrogen atom. Moisture-hydrolyzable groups bonded to N include N,
Examples thereof include N-diorganoamino group, N-organoamide group, and isocyanate group. When three or more silanol groups are present in one molecule of such a moisture-hydrolyzable group component (A), it is sufficient that at least two silanol groups are present in one molecule, and two silanol groups are present in one molecule of component (A). When you do 1
There must be at least 3 in the molecule. If this requirement is satisfied, this component may be a silane or a low polymerization degree polysiloxane. The silane includes not only silane having a single silicon atom in the narrow sense, but also disilane and a silane compound in which silicon atoms are connected to each other by a hydrocarbon group. When this component has a silicon atom-bonded organic group, examples of this organic group include an alkyl group, an alkenyl group, an aryl group, and a substituted alkyl group. Specific examples of the component (D) include methyltrimethoxysilane, methyltri (methylethylketoxime) silane,
Ethyltri (methylethylketoxime) silane, vinyltri (methylethylketoxime) silane, phenyltri (methylethylketoxime) silane, methyltriacetoxysilane, vinyltriacetoxysilane, phenyltriacetoxysilane, dimethyldiacetoxysilane, methylethoxydiacetoxysilane, methyltri ( N, N
-Diethylaminoxy) silane, vinyltri (N, N-)
Diethylaminoxy) silane, vinyltri (N-cyclohexylamino) silane, vinyltri (α-methylvinyloxy) silane, vinyltri (N-methylacetamido) silane, tetraacetoxysilane, tetra (methylethylketoxime) silane, diethoxydi (methylethylketoxime) silane , Dimethyltetraacetoxydisiloxane, divinyltetra (methylethylketoxime)
Disiloxane, trivinylpentaethoxysiloxane,
formula

[0010]

[Chemical 1]

Examples thereof include low molecular weight polysiloxanes represented by: As the component (D), these silanes or low-polymerization degree polysiloxanes may be used alone or in combination of two or more kinds. When two or more kinds are mixed and used, a silane or a low-polymerization degree polysiloxane having an alkyl group as an organic group bonded to a silicon atom other than a moisture-hydrolyzable group and a silicon atom other than the moisture-hydrolyzable group are bonded. It is preferable to use a mixture of a silane having an alkenyl group as the organic group or a low-polymerization degree polysiloxane. If the amount of this component (D) is too small, good curability cannot be obtained, and if it is too large, the coating film shrinks during ink curing and a good surface condition cannot be obtained.
The amount of moisture-hydrolyzable groups is 10 to 500 times the amount of silanol groups contained in (A), preferably 20 to 20.
It is used in the amount range equivalent to 0 times.

Although not essential in the present invention, it is desirable to incorporate (E) vinylalkoxysilane as an adhesion-imparting agent for further improving the adhesiveness. As this (E) component,
Examples thereof include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinylmethyldimethoxysilane, and dimethylvinylmethoxysilane. The amount of component (E) compounded is 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, per 100 parts by weight of component (A).

The conductive silicone ink composition according to the present invention is obtained by mixing the above-mentioned components (A) to (D) and (E) with a universal kneader, and further, if necessary, the consistency, viscosity and Dry process silica, wet process silica, silicas whose surfaces are hydrophobized with silanes or siloxanes, silica aerogels for adjusting the strength of the cured film, etc.
For thickeners / thickeners such as diatomaceous earth, fine quartz powder, talc, and thixotropic agents, and for adjusting the curability,
Carboxylic acid metal salts such as iron octoate, cobalt octoate, manganese octoate, zinc octoate, tin naphthenate, tin carbylate, tin oleate: dibutyltin diacetate, dibutyltin dioctoate, dibutyltin dilaurate, dibutyltin dioleate, diphenyltin diacetate, Organotin compounds such as dibutyltin oxide, dibutyltin dimethoxide, dibutylbis (triethoxysiloxy) tin, dioctyltin dilaurate: tetrabutyl titanate, tetra-2-ethylhexyl titanate, triethanolamine titanate, tetra (isopropenyloxy) titanate, etc. Organic titanic acid ester: Organosiloxy titanium, β-carbonyl titanium and other organic titanium compounds: Alkoxyl Etc. Miniumu compound, further other known fillers, plasticizers, colorants, heat resistance improvers, flame retardants, may be fungicides, etc. are blended in a range not impairing the effects of the present invention.

The composition of the present invention is prepared by uniformly mixing the components (A) and (B), then heating and stirring at a temperature of 100 ° C. or higher for 30 minutes or more, or letting the mixture stand until the temperature is safe. After cooling, add component (C), and then disperse evenly
Blend (D) and mix until uniform. The heat treatment in this production method is performed in order to suppress separation when the composition according to the present invention is further diluted with a solvent or the like. Also ingredients
The compounding of (C) before the component (D) is carried out for the purpose of stabilizing the particle size of the composition according to the present invention. This manufacturing method does not need to be performed in an atmosphere in which moisture is shielded, but the component (D)
When blending and dispersing, it is preferable to perform in an atmosphere in which moisture is blocked.

[0015]

EXAMPLES The present invention will be described below with reference to examples.
In the examples, all parts are parts by weight. Example 1 having a silanol group at both ends and having a viscosity at 25 ° C. of about
Kneading 100 parts of 3000 cP polydimethylsiloxane and 65 parts of carbon black manufactured by acetylene exothermic decomposition method with chlorine absorption of 10 ml / 5 g and iodine adsorption of 48 mg / g at 150 ° C for 2 hours using a universal kneader. After that, it was uniformly diluted with 450 parts of Exxon naphtha No. 5, and then 30 parts of methyltri (methylethylketoxime) silane and 10 parts of vinyltri (methylethylketoxime) silane were mixed to obtain a conductive silicone ink composition. It was This composition is used as a heat vulcanizing type silicone rubber TSE221 manufactured by Toshiba Silicone Co., Ltd.
It was transferred onto a -5U molded sheet by using a brass stamper and heat-cured for 5 minutes in an oven set at 200 ° C to observe the surface condition of the coating film and the adhesiveness with the molded sheet.
The results are shown in Table 1. Furthermore, this composition is coated on a polyester film and dried to form a coating layer with a thickness of about 50 μm, which is then pre-dried in an oven at 80 ° C for 20 minutes and then heated in an oven at 200 ° C for 1 hour. To complete the curing. After cooling this to room temperature once, the volume resistivity of the silicone coating film formed by changing the temperature condition of the atmosphere was measured. The results are shown in Table 2. Comparative Examples 1 to 3 having vinyl groups at both ends, the viscosity at 25 ℃ is about 3000
100 parts of cP polydimethylsiloxane and 65 parts of carbon black produced by the acetylene exothermic decomposition method with chlorine absorption of 10 ml / 5 g and iodine adsorption of 48 mg / g are heated and kneaded for 2 hours at 150 ° C using a universal kneader. After that, it was uniformly diluted with 450 parts of Exxon's naphtha No. 5 and used as a crosslinking agent component.
2 parts of polymethylhydrogensiloxane containing 0.9% by weight of Si-H group and blocked at both ends with trimethylsilyl groups and having a viscosity of 20 cP, 3,5-dimethyl-1-hexyne-3-ol as a reaction inhibitor 0.3 part, formula

[0016]

[Chemical 2]

A mixture of 2 parts of the compound represented by the formula and 1% by weight of chloroplatinic acid in isopropyl alcohol as a curing catalyst was added to the above polydimethylsiloxane in an amount of 20 ppm as platinum atom and kneaded. To obtain a composition of Comparative Example 1 uniformly dispersed. Further, the composition of Comparative Example 2 in which the amount of the reaction inhibitor in Comparative Example 1 was increased to 0.6 part and the composition of Comparative Example 3 in which the amount of the reaction inhibitor was increased to 0.9 part were obtained, For these, as in Example 1, a thermal vulcanization type silicone rubber T manufactured by Toshiba Silicone Co., Ltd.
It was transferred onto a SE221-5U molded sheet using a brass stamper and heat-cured for 5 minutes in an oven set at 200 ° C. to observe the surface state of the coating film and the adhesiveness with the molded sheet. The results are shown in Table 1.

[0018]

[Table 1]

As shown in Table 1, it can be seen that the composition of Example 1 shows a remarkable improving effect on the surface condition of the coating film and the adhesiveness between the molded sheet.

Comparative Example 4 Instead of the carbon black used in Example 1, a chlorine absorption amount of 16 ml / 5 g produced by the acetylene exothermic decomposition method,
Comparative Example 4 using carbon black having an iodine adsorption amount of 58 mg / g was coated on a polyester film and dried in the same manner as in Example 1 to form a coating layer having a thickness of about 50 μm. It was pre-dried in an oven for 20 minutes and then heated in an oven at 200 ° C for 1 hour to complete curing. After cooling this to room temperature once, the volume resistivity of the silicone coating film formed by changing the temperature condition of the atmosphere was measured. The results are shown in Table 2.

[0021]

[Table 2]

As shown in Table 2, it can be seen that the composition of Example 1 shows a remarkable improving effect on the stability of the conductivity due to the change in the ambient temperature.

Examples 2 to 3 For Example 2 in which the amount of naphtha No. 5 was 150 parts and Example 3 in which the amount of naphtha No. 5 was 750 parts in Example 1, brass stampers were used. The silicone rubber molded sheet was used and cured, and the transferability was evaluated. The results are shown in Table 3. Comparative Examples 5 to 6 Similar to Examples 2 and 3, Comparative Example 5 in which the amount of naphtha No. 5 was 50 parts in Example 1 and Comparative Example 6 in which the amount of naphtha No. 5 was 1050 parts were used. Evaluated to. The results are shown in Table 3.

[0024]

[Table 3]

As shown in Table 3, it can be seen that the compositions of Examples 2 and 3 have good transferability.

Examples 4 to 5 In Example 1, the amount of methyltri (methylethylketoxime) silane compounded was 3.75 parts, and the amount of vinyltri (methylethylketoxime) silane compounded was 1.25 parts (moisture-hydrolyzable group amount relative to silanol group amount). Of about 11 times), and the compounding amount of methyltri (methylethylketoxime) silane was 120 parts, and the compounding amount of vinyltri (methylethylketoxime) silane was 40 parts (moisture-hydrolyzable group amount relative to silanol group amount). Example 5 in which the temperature was about 350 times) was transferred onto a silicone rubber molded sheet using a brass stamper and heat-cured for 5 minutes in an oven set at 200 ° C to improve the surface condition and curability of the coating film. I observed. The results are shown in Table 4. Comparative Examples 6 to 7 In Example 1, the compounding amount of methyltri (methylethylketoxime) silane was 1.5 parts, and the compounding amount of vinyltri (methylethylketoxime) silane was 0.5 part (the amount of moisture-hydrolyzable groups was about 4.4 relative to the amount of silanol groups). Comparative Example 6 and the compounding amount of methyltri (methylethylketoxime) silane was 240 parts, and the compounding amount of vinyltri (methylethylketoxime) silane was 80 parts (based on the silanol group amount,
Regarding Comparative Example 7 in which the amount of moisture-hydrolyzable groups was about 700 times), a brass stamper was used to transfer the composition onto a silicone rubber molded sheet, which was then heat-cured for 5 minutes in an oven set at 200 ° C. to form a coating film. The curability and surface condition were observed. The results are shown in Table 4.

[0027]

[Table 4]

As shown in Table 4, it can be seen that the compositions of Examples 4 and 5 show good results in the curability and surface condition of the coating film.

Comparative Example 8 Comparative Example 8 was carried out in the same manner as in Example 1 except that the heating and kneading was not performed, and the presence or absence of liquid separation of the composition was evaluated under the conditions of standing at 25 ° C. for 70 hours. . The results are shown in Table 5.

[0030]

[Table 5]

As shown in Table 5, it can be seen that the composition of Example 1 exhibits good storage stability.

Comparative Example 9 Comparative Example 9 was carried out in the same manner as in Example 1 except that the solvent was mixed in the last time in Example 1, and the production was repeated 5 times. Examined. The results are shown in Table 6.

[0033]

[Table 6]

As shown in Table 6, it can be seen that the composition of Example 1 shows good results in stabilizing the production viscosity.

Example 6 The composition of Example 1 was further supplemented with 2 parts of vinyltriethoxysilane.
Parts to obtain the composition of Example 6, which was transferred to a molded sheet of thermal vulcanizing silicone rubber TSE221-5U manufactured by Toshiba Silicone Co., Ltd. using a brass stamper in the same manner as in Example 1. Then, it was cured by heating in an oven set to 200 ° C. for 5 minutes, and the surface condition of the coating film and the adhesiveness to the molded sheet were observed, and all were very good.

Claims (4)

[Claims] 1. The following components (A), (B), (C) and (D)
A conductive silicone ink composition containing: (A) is represented by the average unit formula R _a SiO _{(4-a) / 2} (wherein each R represents a substituted or unsubstituted monovalent hydrocarbon group, and a represents a number from 1.98 to 2.02). Polyorganosiloxane having at least two silanol groups in one molecule; 100 parts by weight (B) Amount of chlorine absorption produced by the acetylene exothermic decomposition method
Carbon black of 12 ml / 5 g or less and iodine adsorption amount of 50 mg / g or less; 10 to 100 parts by weight (C) solvent; 100 to 1000 parts by weight (D) Moisture bonded to silicon atom by oxygen atom or nitrogen atom in one molecule A silane or low-polymerization polysiloxane having at least two hydrolyzable groups (however, when the number of silanol groups in the component (A) is two in one molecule, at least three); included in the component (A) Moisture-hydrolyzable groups equivalent to 10 to 500 times the amount of silanol groups 2. The component (D) is a silane or low-polymerization degree polysiloxane having an alkyl group as an organic group bonded to a silicon atom other than the moisture-hydrolyzable group, and a silicon atom other than the moisture-hydrolyzable group. The conductive silicone ink composition according to claim 1, which is a mixture of a silane having an alkenyl group as the organic group or a low-polymerization degree polysiloxane. 3. The composition further comprises 0.01 to 10 parts by weight of (E) vinylalkoxysilane as an adhesion promoter.
Or the conductive silicone ink composition according to item 2. 4. The components (A) and (B) are mixed and heat-treated,
A method for producing a conductive silicone ink, which comprises adding the component (C) and uniformly dispersing the component (D).