JPH11189722A - Electrically conductive curable organopolysiloxane composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition having excellent storage stability and high electrical conductivity and useful as a silicone ink for coating, marking, electronic circuit use, etc., by including a specific silicon-functional polydiorganosiloxane, a carbon-based electrically conductive filler, a titanium- containing organic compound, etc., and a solvent. SOLUTION: The objective composition is produced by including (A) a straight-chain silicon-functional polydiorganosiloxane of the formula [R<1> is a univalent hydrocarbon group; R<2> is a group of the formula; O-SiR<3> 3- P(OR<4> )P (R<3> is a univalent hydrocarbon group; R<4> is a univalent aliphatic hydrocarbon group; P is 1-3); (n) is a number to give the component A having a viscosity of 50-100,000 cP at 25 deg.C], (B) a carbon-based electrically conductive filler, (C) an organic compound containing titanium or zirconium and (D) a solvent. The component B is preferably a carbon black produced by the exothermic decomposition of acetylene and having a chlorine liquid absorption of <=12 mL/5 g and an iodine adsorption of <=50 mg/g.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curable conductive organopolysiloxane composition having excellent storage stability, a long pot life even at room temperature and in the presence of moisture, and having high conductivity by heating for a short time. About.

[0002]

2. Description of the Related Art Conventionally, a curable conductive organopolysiloxane composition in which a carbon-based filler is blended with a curable organopolysiloxane composition so as to impart conductivity to the cured product, A composition which is diluted with a solvent to obtain an ink solvent is known, and is used for applications such as a switching function and an electric circuit.

[0003] However, in order to impart high conductivity to silicone rubber using a carbon-based filler, it is necessary to highly fill the organopolysiloxane composition with the carbon-based filler. Significantly higher and the composition becomes extremely viscous. Although it is possible to reduce the viscosity by diluting with a solvent, an extremely large amount of solvent is required to reduce the viscosity, in such a case,
It adversely affects the conductivity after curing and the strength of the cured product. Also,
Organopolysiloxane compositions containing commonly used carbon black have extremely poor dispersibility and solubility when dissolved in a solvent, and are easy to separate even after dissolution, making it possible to obtain a uniform composition. There is a disadvantage that it is difficult.

As a technique for solving such a problem, Japanese Patent Application Laid-Open No. H11-16666 discloses an electrically conductive silicone prepared by using an addition-curable polyorganosiloxane as a base polymer and blending a specific carbon black and a solvent. Although a composition has been proposed and has excellent conductivity and uniformity of the composition, the addition reaction type polyorganosiloxane composition is used. Since the process proceeds, the pot life is short, and further, there is a problem that preliminary curing is required to volatilize the solvent first when heating and curing.

JP-A-4-93359 proposes a composition in which a carbon-based filler and a polyether compound are blended with a room-temperature-curable organopolysiloxane composition. Since the composition cures in the presence of moisture therein, it cannot be used for a long time under conditions where moisture is present at room temperature.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has excellent storage stability, can be used for a long time at room temperature and in the presence of moisture, and can be cured by heating for a short time. It is another object of the present invention to provide a curable conductive organopolysiloxane composition having high conductivity.

[0007]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have used a specific silicon-functional polyorganosiloxane as a base polymer and a specific carbon-based polyorganosiloxane. The present inventors have found that a composition containing a material, an organic compound containing titanium or zirconium and a solvent satisfies the above object, and have completed the present invention.

That is, the present invention provides the following component (A):
A curable conductive organopolysiloxane composition containing (B), (C) and (D).

That is, the curable conductive polyorganosiloxane composition of the present invention has the following general formula (A):

Embedded image Wherein R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different; R ² represents —O
—SiR ³ _3-P (OR ⁴ ) _P , R ³ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different, and R ⁴ represents an unsubstituted or alkoxy-substituted group. Represents a monovalent aliphatic hydrocarbon group, P is a number of 1 to 3, and n is a viscosity of the component (A) at 25 ° C of 50 to 50.
A substantially linear silicon-functional polydiorganosiloxane, the number being 100,000 cP).
(B) a carbon-based conductive filler, (C) an organic compound containing titanium or zirconium, and (D) a solvent.

The component (A) is a base polymer in the composition of the present invention, and is a substantially linear silicon-functional polyorganosiloxane represented by the above-mentioned general formula. Is also good. The terminal group R ² is a silicon-functional siloxy unit having at least one silicon-functional group OR ⁴ . That is, the component (A) has at least one silicon-functional OR ⁴ group at each end of the molecule.

R ¹ is a substituted or unsubstituted monovalent hydrocarbon radical which may be the same or different. R ¹
And alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl and dodecyl; alkenyl groups such as vinyl and allyl; aryl groups such as phenyl, tolyl and xylyl;
Aralkyl groups such as -phenylethyl, 2-phenylpropyl; and those in which some of the hydrogen atoms of these hydrocarbon groups have been replaced with other atoms or groups, ie, chloromethyl, 3-chloropropyl, 3,3,3-
Halogenated alkyl groups such as trifluoropropyl;
A substituted hydrocarbon group such as a cyanoalkyl group such as 3-cyanopropyl is exemplified. Of these, 85% or more of all organic groups are methyl groups because of ease of synthesis, component (A) having a low viscosity relative to the molecular weight, and imparting good physical properties to the cured composition. It is particularly preferable that substantially all organic groups are methyl groups.

R bonded to the silicon atom of the terminal group R ^2
3 may be the same or different, and R ¹
Is a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different, and examples thereof are the same as those of R ¹ .
Synthesis is easy, since the reactivity of the OR ⁴ is superior,
A methyl group or a vinyl group is preferred.

R ⁴ is an organic group constituting a part of the silicon functional group OR ⁴ present in at least one terminal group R ² and bonding to the silicon atom via an oxygen atom. R ⁴ is an alkyl group such as methyl, ethyl, propyl, or butyl; 2-methoxyethyl, 2-ethoxyethyl, 2-
Illustrative are alkoxy-substituted alkyl groups such as butoxyethyl, 3-methoxypropyl, 4-methoxybutyl; and alkenyl groups such as isopropenyl, which may be the same or different. Because of the ease of synthesis, the physical properties of the composition before curing, the stability during storage, the curability, the economy, and the use in a wide range of applications, methyl, ethyl,
2-methoxyethyl and isopropenyl are preferred,
Methyl groups are most preferred.

The number p of the silicon functional group OR ⁴ in the terminal group R ² is 1 to 3. Among them, p is most preferably 3 because of excellent reactivity.

As the component (A) of the present invention, specifically,
α, ω-bis (methyldimethoxysilyl) polydimethylsiloxane, α, ω-bis (triethoxysilyl) polydimethylsiloxane, α, ω-bis (trimethoxysilyl) polydimethylsiloxane, α, ω-bis [methylbis ( 2-methoxyethyl) silyl] polydimethylsiloxane, α, ω-bis (methyldiethoxysilyl) polydimethylsiloxane and the like.

It also provides excellent mechanical properties after curing,
In addition, from the ease of compounding the carbon-based filler, n of component (A)
Has a viscosity at 25 ° C. of 50 to 100,0
00 cP, preferably between 500 and 20,000 cP. When the viscosity is at the end of 50 cP, the mechanical strength after curing is low. On the other hand, when the viscosity exceeds 100,000 cP, it becomes difficult to mix the carbon-based filler.

The component (A) of the present invention can be used alone or
You may use 2 or more types together.

The carbon-based filler as the component (B) in the present invention is one of the components of the present invention which imparts excellent conductivity and moderately suppresses the viscosity of the composition. Examples thereof include carbon black such as acetylene black, furnace black, thermal black, lamp black, and channel black, carbon fiber, and graphite. In particular, a chlorine absorption of 12 ml / 5 g produced by an acetylene exothermic decomposition method. Hereinafter, carbon black having an iodine adsorption amount of 50 mg / g or less is suitable for achieving the object of the present invention.

The meaning of these quality characteristics is as follows. That is, the chlorine absorption amount specified in JIS K1469 (acetylene black) is an index indicating the degree of development of the structure “chain structure of primary carbon particles”, and iodine adsorption specified in JIS K 1474 “Test method for powdered activated carbon”. It is known that quantity is an indicator of the strength of a structure.

Here, when imparting conductivity to the rubber composition, the more developed the structure, that is, the larger the amount of chlorine absorbed, and the stronger the structure, that is, the larger the amount of adsorbed iodine, the more the carbon becomes. It is considered more desirable because the probability of secondary contact increases and the structure is less likely to be broken by the stress of mixing or kneading.

However, the silicone-based polymer, which is much softer than other organic polymers, does not apply the conventional wisdom, and requires an appropriate structure to enable uniform dispersion.

That is, in order to impart good workability to the compound or the composition and to give good conductivity, the acetylene black should have a chlorine absorption of 12 ml / 5.
g or less and the iodine adsorption amount must be 50 mg / g or less. If any of the values exceeds the above values, good workability and good conductivity cannot be imparted.

If the amount of the component (B) is too small, good conductivity cannot be imparted. If the amount is too large, the mechanical properties of the conductive coating film obtained by curing the component deteriorate. It is used in an amount of 10 to 100 parts by weight, preferably 30 to 80 parts by weight, based on 100 parts by weight of the component (A).

The component (B) of the present invention can be used alone or
Also, two or more kinds may be used in combination.

The component (C) used in the present invention is used for curing the composition of the present invention. The component (C) includes titanium tetraethoxide, titanium tetra-n-propoxide, titanium tetraisotoxide. Propoxide, titanium tetra-n-butoxide, titanium tetra-sec-butoxide, titanium tetrakis (2-ethylhexyl oxide)
Or a partially hydrolyzed condensate thereof; titanium triisopropoxypropylene glycolate, titanium triisopropoxyoctylene glycolate, titanium di-n-butoxybishexylene glycolate, titanium di- titanium glycolates such as n-butoxybisoctylene glycolate and titanium bis (octylene glycolate); titanium alkoxide derivatives such as triethanolamine titanate; diisopropoxybis (acetylacetonato) titanium; -Propanedioxybis (acetylacetonato) titanium, bis (acetylacetonato) titanyl, tetrakis (acetylacetonato) titanium, diisopropoxybis (methylacetoacetato) titanium, diisopropoxybis (ethy Asetoasetato) titanium, 1,3
Titanium chelate compounds such as propanedioxybis (ethylacetoacetato) titanium; zirconium tetra-
Examples include zirconium alkoxides such as n-butoxide and partially hydrolyzed condensates thereof; zirconium chelate compounds such as tetrakis (acetylacetonato) zirconium and dibutoxybis (ethylacetoacetato) zirconium.

The component (C) exerts its curing performance particularly when the component (A) contains an alkoxy group.

The amount of the component (C) is 100 parts.
0.01 to 10 parts by weight per part by weight, preferably 0.1 to 10 parts by weight
-5 parts by weight. At the end of 0.01 part by weight, it does not act sufficiently as a curing catalyst. Conversely, when the amount exceeds 10 parts by weight, it has no effect corresponding to the blending amount and is not only meaningless but also economically disadvantageous. And storage stability is deteriorated.

The component (C) of the present invention can be used alone or
Also, two or more kinds may be used in combination.

The solvent of the component (D) is (A), (B)
And for uniformly dispersing or dissolving the mixture of component (C) and having a role of adjusting the viscosity according to the application. Such solvents include toluene, xylene, cyclohexane, n-hexane, n-heptane, n-octane,
Hydrocarbon solvents such as naphtha, mineral spirits and petroleum benzene; halogenated hydrocarbon solvents such as chloroform, hydrogen tetrachloride, trichloroethylene, perchloroethylene, 1.1.1-trichloroethane, perfluoropropane; propyl ether , N-butyl ether,
Ether solvents such as anisole, tetrahydrofuran and ethylene glycol diethyl ether; ester solvents such as ethyl acetate, butyl acetate and amyl acetate;
Ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and acetophenone; methanol, ethanol, isopropanol, butanol, 2-
Alcohol solvents such as methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, ethylene glycol and propylene glycol; chains such as hexamethyldisiloxane, tetramethyldiphenyldisiloxane, octamethyltrisiloxane, and decamethyltetrasiloxane Siloxane solvents; hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane,
Examples thereof include cyclic siloxane solvents such as heptamethylphenylcyclotetrasiloxane, heptamethylvinylcyclotetrasiloxane, and decamethylcyclopentasiloxane. The amount of the solvent is not particularly limited, but is usually 50 to 1000 parts by weight, preferably 100 to 500 parts by weight, per 100 parts by weight of the component (A).

The component (D) of the present invention can be used alone or
Two or more kinds may be used in combination.

In the composition of the present invention, component (A) 10
0 parts by weight, 10 to 100 parts by weight of component (B), 0.01 to 10 parts by weight of component (C) and 50 to 1000 of component (D)
Parts by weight, and (A)
100 parts by weight of the component, 30 to 80 parts by weight of the component (B),
0.1 to 5 parts by weight of component (C) and 100 to 100 parts of component (D)
More preferably, 500 parts by weight is contained.

Further, in the curable conductive organopolysiloxane composition of the present invention, the above (A), (B),
In addition to the essential components (C) and (D), fumed silica,
Silica-based fillers such as precipitated silica; titanium dioxide;
Reinforcing agents such as aluminum oxide, quartz powder, talc and bentonite; fibrous fillers such as asbestos, glass fibers and organic fibers; coloring agents such as pigments and dyes; adhesives such as γ-aminopropyltriethoxysilane Heat-resistant additives such as red iron oxide and cerium oxide; cold-resistant additives; flame retardants; plasticizers; processing aids;
A dehydrating agent; a rust preventive and the like can be appropriately added as needed.

The composition of the present invention may be used at a temperature of 100 ° C. to 25 ° C.
The composition is cured by heating at a temperature of 0 ° C, preferably 130 ° C to 200 ° C. That is, since the composition is not cured at room temperature or cured by ultraviolet irradiation, it has excellent storage stability and light stability.

Although the use of the composition of the present invention is not particularly limited, it can be used as a silicone ink for painting and marking, and can be used for a switching function and an electronic circuit because of its excellent conductivity.

[0035]

Now, the present invention will be described in further detail with reference to Examples and Comparative Examples. In the examples,
All “parts” indicate “parts by weight”, and all physical property values such as viscosity are values at 25 ° C. and 60% relative humidity.

Example 1 α, ω having a viscosity of 3,000 cP
100 parts of bis (methyldimethoxysilyl) polydimethylsiloxane, 48 mg / g of iodine adsorbed by acetylene exothermic decomposition method, 10 ml / 5 of chlorine adsorbed liquid
g of carbon black in 1 part using a universal kneader.
After heating and kneading at 50 ° C. for 2 hours, 1 part of titanium tetra-n-butoxide was added, and Naphtha No.
5 was uniformly diluted with 400 parts to obtain a curable conductive organopolysiloxane composition.

Storage stability of the composition thus obtained,
The pot life in the presence of moisture at normal temperature, the conductivity after curing, and the adhesion to the formed silicone rubber sheet were evaluated as follows.

The storage stability was evaluated by placing the above-mentioned composition in a glass bottle, sealing it, and allowing it to stand at 50 ° C. for 3 days, returning it to room temperature, and measuring its viscosity.

The pot life at normal temperature and in the presence of moisture is determined by placing the above composition in a glass bottle and leaving it unsealed at 25 ° C. and a relative humidity of 60%, and measuring the change in viscosity over time. Was evaluated. Further, this composition was dried on a polyester film and applied so as to have a thickness of about 50 μm, and this was heated in an oven at 180 ° C. for 10 minutes to complete the curing. Once cooled to room temperature, the volume resistivity after curing was measured using a digital multimeter manufactured by Advantest Corporation.

Further, this composition was applied on a sheet of heat-curable silicone rubber TSE221-5U manufactured by Toshiba Silicone Co., Ltd., heated and cured in an oven at 180 ° C. for 10 minutes, and the adhesion to the formed sheet was observed. did.

Further, this composition was added to 20 × 50 × 150.
After being placed in a mold having a diameter of 150 mm and cured at 150 ° C. for 30 minutes, and left at room temperature for 24 hours, the thermal conductivity was measured with a rapid thermal conductivity meter QTM-500 manufactured by Kyoto Electronics Industry Co., Ltd.
Table 1 shows the results.

[0042]

[Table 1] Example 2 The composition of Example 2 was obtained by using α, ω-bis (triethoxysilyl) polydimethylsiloxane having a viscosity of 3,000 cP instead of the polydimethylsiloxane in Example 1. This was evaluated in the same manner as in Example 1. The results are also shown in Table 1.

Example 3 A composition of Example 3 was obtained by using diisopropoxybis (methylacetoacetato) titanium in place of titanium tetra-n-butoxide in Example 1. This was evaluated in the same manner as in Example 1. The results are also shown in Table 1.

Example 4 Using 45 parts of carbon black in Example 1, 3 parts of zirconium tetra-n-butoxide instead of titanium tetra-n-butoxide, and 300 parts of Naphtha No5 manufactured by Exxon Co. Example 4
Was obtained. This was evaluated in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 1 A composition of Comparative Example 1 was obtained in the same manner as in Example 1 except that titanium tetra-n-butoxide was not used. This was evaluated in the same manner as in Example 1. The results are also shown in Table 1.

(Comparative Examples 2-3) α, ω in Example 1
Composition using α, ω-dihydroxypolydimethylsiloxane having a viscosity of 3,000 cP in place of bis (methyldimethoxysilyl) polydimethylsiloxane (Comparative Example 2) and dibutyltin in place of titanium tetra-n-butoxide The same evaluation as in Example 1 was performed for each of the compositions using Geoctoate (Comparative Example 3). The results are also shown in Table 1.

Comparative Example 4 A composition of Comparative Example 4 was obtained by adding 2 parts of methyltrimethoxysilane and 3 parts of hexamethyldisilazane to 100 parts of the composition of Comparative Example 3. This was evaluated in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 5 α, ω having a viscosity of 3,000 cP
-Bis (dimethylvinyl) polydimethylsiloxane 10
To 0 parts, 65 parts of the carbon black used in Example 1 was heated and kneaded at 150 ° C. for 2 hours using a universal kneader in the same manner as in Example 1, and Naphtha No.
The mixture was uniformly diluted with 00 parts, and 1 part of methyl hydrogen siloxane having a viscosity of 20 cP and chloroplatinic acid were added in an amount of 5 ppm as platinum element amount per 100 parts,
The composition of Comparative Example 5 was obtained by uniformly mixing. The same evaluation was performed for this. The results are also shown in Table 1.

As is evident from Table 1, the compositions of Examples 1 to 4 all showed little change in viscosity and were excellent in adhesion to a molded sheet and conductivity. On the other hand, the compositions of Comparative Examples 1 to 5 were too cured, did not cure, and had a large change in viscosity due to aging.

[0050]

According to the present invention, a specific silicon-functional polyorganosiloxane is used as a base polymer,
By blending a specific carbon-based filler with a titanium or zirconium-containing organic compound and a solvent,
It is excellent in storage stability, can be used for a long time even at normal temperature and in the presence of humidity, and can be cured by heating for a short time to realize a curable conductive organopolysiloxane composition having high conductivity.

[0051]

Claims (2)

[Claims] (A) General formula (A) (Wherein, R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different from each other; R ² represents —O—
Represents SiR ³ _3-P (OR ⁴ ) _P , R ³ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different, and R ⁴ represents an unsubstituted or alkoxy-substituted group. P represents a monovalent aliphatic hydrocarbon group, P is a number of 1 to 3; n represents a viscosity of the component (A) at 25 ° C. of 50 to 1;
A substantially linear silicon-functional polydiorganosiloxane having a number of
A curable conductive organopolysiloxane composition comprising (B) a carbon-based conductive filler, (C) an organic compound containing titanium or zirconium, and (D) a solvent. 2. The (B) carbon-based conductive filler has a chlorine absorption of 12 m produced by an acetylene exothermic decomposition method.
The curable conductive organopolysiloxane composition according to claim 1, wherein the composition is 1/5 g or less and the iodine adsorption amount is 50 mg / g or less.