JPH04220469A - Conductive coating composition - Google Patents

Abstract

PURPOSE:To provide a water-based composition for forming a water-resistant and solvent-resistant conductive coating film effective in preventing electrostatic troubles arising in the field of electronics or the like. CONSTITUTION:A composition prepared by mixing 70-97wt.% water-soluble, ionically conductive resin with 3-30wt.% thermally cross-linking monomer. When applied and heated, this composition can form a water-resistant and solvent- resistant transparent coating film having an excellent conductivity (surface resistivity) of about 10<7>OMEGA/square.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention relates to a composition for forming a conductive coating film, particularly for forming a conductive coating film for effectively preventing electrostatic damage occurring in equipment parts and devices in the field of electronics. The present invention relates to a composition.

0002

[Prior Art] As an antistatic treatment for plastic substrates, etc., a certain type of surfactant is applied to the surface of the plastic substrate or mixed into the plastic substrate. Conductive materials such as carbon are kneaded into the base material.

[0003] In these known antistatic treatments, the method of applying a surfactant to a plastic substrate generally results in a coating film that is poor in water resistance and may easily separate from the surface. At the same time, there are many problems with durability, such as the paint film becoming sticky or deteriorating due to moisture adsorption, and the surface resistance value of the paint film is generally 109 ohms/square or more, which is not considered to be a sufficiently conductive paint film. There are many difficult things. Furthermore, although the method of kneading carbon or the like into a plastic base material has fewer problems than the above-mentioned processing means, it does have the problem that the transparency of the obtained product is inhibited by the conductive material such as carbon mixed in. Therefore, in IC chip storage containers, etc., which require transparency as well as antistatic performance, antistatic treatment with even better performance is required. As disclosed in the publication, a technique has been developed in which a water-soluble ion conductive resin is blended with a photopolymerizable monomer and a water-resistant conductive coating is formed by irradiation with ultraviolet rays.

0004

[Problem to be solved by the invention] Said Japanese Patent Publication Publication No. 61-24
The antistatic technology using ultraviolet irradiation disclosed in Publication No. 413, etc., has a surface resistance value of approximately 1010 or less of the surface resistance of the film obtained by this method, compared to the case of using the above-mentioned surfactant or carbon. Although it has the advantage of being able to apply UV rays, it requires preliminary treatment such as corona discharge treatment on the object to be coated in advance when forming a coating film, and it also requires equipment for UV irradiation after coating, making it difficult to operate and equipment. There are many restrictions, and the economic burden caused by these is unavoidable.

In view of the current situation, the present invention has been developed as a result of intensive research and testing, and has been developed to achieve water resistance and resistance by crosslinking in an aqueous solvent and at a relatively low temperature, without using organic solvents that cause pollution. A composition for forming a conductive coating film that has excellent solvent properties and is capable of producing a transparent conductive polymer coating film has been completed.

[0006]

[Means for Solving the Problems] The conductive coating composition of the present invention contains a water-soluble ion conductive resin (A) of 70 to 97%
% by weight and a thermally crosslinkable monomer (B) in a range of 3 to 30% by weight.

Specifically, the water-soluble ionically conductive resin (A) constituting the conductive coating composition of the present invention has a cationic quaternary ammonium base in its side chain, and A monofunctional vinyl monomer having a polymerizable double bond, a monofunctional vinyl monomer having a hydroxyl group that serves as a crosslinking reactive group,
This is a copolymer obtained by copolymerizing these monomers with other polymerizable vinyl monomers.

[0008] In the copolymer, there is a cationic quaternary group in the side chain.
Examples of monofunctional vinyl monomers having an ammonium base and a polymerizable double bond at the terminal include dimethylaminoethyl acrylate quaternary compounds, dimethylaminoethyl methacrylate quaternary compounds, and diethylaminoethyl acrylate quaternary compounds. , diethylaminoethyl methacrylate quaternary compound, methylethylaminoethyl acrylate quaternary compound, methylethylaminoethyl methacrylate quaternary compound, dimethylaminostyrene quaternary compound, diethylaminostyrene quaternary compound, methylethylaminostyrene quaternary compound, etc. These can be used alone or in combination of two or more. On the other hand, examples of the monofunctional vinyl monomer having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxyethyl acrylate,
-Hydroxyethyl methacrylate. Other polymerizable vinyl monomers that can be copolymerized with these monomers include acrylic acid alkyl esters such as methyl acrylate and ethyl acrylate, and methacrylic acid alkyl asters such as methyl methacrylate and ethyl methacrylate. , styrene, vinyl toluene, vinyl acetate and the like.

A monofunctional vinyl monomer (X) having a cationic quaternary ammonium base and having a polymerizable double bond at the terminal in this water-soluble ion-conductive resin (A).
The copolymerization ratio of the monofunctional vinyl monomer (Y) having a hydroxyl group, and the other polymerizable vinyl monomer (Z) is (
The polymerization ratio of Y+Z)/X is preferably in the range of 5/1 to 2/1. If this polymerization ratio exceeds 5/1, the water solubility of the ion conductive resin (A) may decrease or the cationic type polymerization ratio may decrease. As a result, the ratio of the monofunctional vinyl monomer (X) having a quaternary ammonium base and a polymerizable double bond at the end decreases, making it impossible to obtain a coating film with the desired surface resistance value. . Moreover, when the polymerization ratio is less than 2/1, the water resistance of the coating film tends to decrease, and the resulting coating film has increased stickiness and blocking properties. In addition, the polymerization ratio of (X+Z)/Y is preferably in the range of 10/1 to 15/1, and if this polymerization ratio exceeds 15/1, the monofunctional Birunimonomer (Y) having a hydroxyl group will decrease. Therefore, when the thermally crosslinkable monomer (B) is added, the resulting crosslinkability is insufficient, making it impossible to obtain a coating film with the desired water and solvent resistance. In addition, when the polymerization ratio is less than 10/1, the amount of monofunctional vinyl monomer (Y) having a hydroxyl group increases as a result,
A coating film with the desired water and solvent resistance cannot be obtained.

The other thermally crosslinkable monomer (B) constituting the conductive coating composition of the present invention is specifically an epoxy compound having 2 to 4 glycidyl groups; Examples include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, diglycerol poly Examples include glycidyl ether, and one or two of these
More than one species can be used.

The blending range of the water-soluble ion conductive resin (A) and the thermally crosslinkable monomer (B) is as follows:
70 to 97% by weight of A) and 30 to 3% by weight of monomer (B). If the ion conductive resin (A) is less than 70% by weight, the thermally crosslinkable monomer (B) will be excessive, and the resulting coating film will have improved water resistance and solvent resistance, but will not have the desired surface resistance. A film of value cannot be obtained. Water-soluble ion conductive resin (
When A) exceeds 97% by weight, the amount of thermally crosslinkable monomer (B) decreases, resulting in a decrease in the reactivity of the crosslinking reaction and a coating that cannot achieve the desired water and solvent resistance. It becomes difficult to obtain a membrane. In addition, water-soluble ion conductive resin (A),
When forming a coating film using a composition consisting of a thermally crosslinkable monomer (B), organic Alternatively, it is desirable to use a small amount of a crosslinking curing agent consisting of an inorganic alkaline compound, such as an amine, a polyamine, an amidoamine, a polyamidoamine, an imidazole, an alkali metal carbonate, or a derivative thereof.

0012

[Operation] The coating film forming composition of the present invention is an aqueous composition prepared by blending a water-soluble ion conductive resin (A) and a thermally crosslinkable monomer (B) in a predetermined ratio. By applying this aqueous composition to the surface of the object to be coated and heating it, the coating film is crosslinked and cured by a thermal crosslinking reaction between the ion conductive resin (A) and the thermally crosslinkable monomer (B). This process forms a transparent, water- and solvent-resistant cured film.

In particular, the water-soluble ion conductive resin (A) used for the purpose of imparting water solubility and conductivity has a cation type quaternary ammonium base in the side chain and a polymerizable polymer at the terminal. Copolymerization of a water-soluble monofunctional vinyl monomer that has formed a double bond, a water-insoluble monofunctional vinyl monomer that has a hydroxyl group that serves as a crosslinking reaction group, and another polymerizable vinyl monomer. The thermally crosslinkable monomer (B) blended into this is composed of an epoxy compound having 2 to 4 glycidyl groups, and this compound is used to form a coating film. By adding a small amount of a crosslinking curing agent made of an organic or inorganic alkaline compound to the composition, it is possible to easily crosslink by heating at a relatively low temperature and form an excellent cured film in a short time and reliably.

[0014]

EXAMPLES The conductive coating film-forming composition of the present invention will be explained in more detail below with reference to Examples and Comparative Examples.

[0015]

[Example 1] Methyl methacrylate/ethyl acrylate/2-hydroxyethyl methacrylate/dimethylaminoethyl methacrylate quaternary compounds were copolymerized in a weight composition ratio of 46/21/7.6/25.4. A combined aqueous solution was obtained. To this aqueous copolymer solution, 4% by weight of glycerol polyglycidyl ether was added as an epoxy compound based on the solid content of the copolymer, and 2-methylimidazole was added as a crosslinking curing agent based on 2% of the glycerol polyglycidyl ether. 5% by weight was added and mixed to obtain an aqueous solution of a coating film forming composition. This aqueous solution was applied onto a polyethylene terephthalate (hereinafter referred to as PET) film to a dry film thickness of 2 microns and cured by heating at a temperature of 100° C. for 10 seconds to obtain a transparent cured film. The results of various physical property tests conducted on this cured film were as follows. (1) Measurement of surface resistance value; temperature 25℃, relative humidity 20%
(2) Adhesion test with PET: 100/100 by cross-cut peeling method (3) Water resistance and solvent resistance test: The cured film before and after the test was tested in various ways. immersed in a solvent (including water), left for 16 hours at a room temperature of 25°C and a humidity of 50% RH, and then dried.
The surface resistance value (ohm/square) was measured and compared. The results of this water resistance and solvent resistance test are shown in Table 1.

[0016]

[Table 1] ┌──────────┬──────
─┬───────┐ │ Melt
Agent │ Before test │ After test │ ├────────
─┼───────┼───────┤
│Water │1.6×1
07 │1.2×107 │ ├────
──────┼────────┼────────┤
│Isopropanol │2.6×107
│2.3×107 │ ├─────
────┼────────┼────────┤
│Methyl ethyl ketone│4.6×107 │2
．． 0×107 │ ├────────
─┼───────┼───────┤
│Ethyl acetate │5.1×107 │
3.4×107 │ ├───────
──┼────────┼────────┤
│Toluene │1.6×107
│3.6×107 │ └─────
────┴────────┴────────┘

001
7]

[Example 2] Methyl methacrylate/ethyl acrylate/2-hydroxyethyl methacrylate/dimethylaminoethyl methacrylate quaternary compounds were used in a weight composition ratio of 51.5/15/7.8/25.7. An aqueous copolymer solution was obtained by polymerization. To this aqueous copolymer solution, 4% by weight of polyethylene glycol diglycidyl ether as an epoxy compound was added based on the solid content of the copolymer. Furthermore, 1.0% by weight of sodium sesquicarbonate was added as a crosslinking curing agent to the polyethylene glycol diglycidyl ether to obtain an aqueous solution of a coating film forming material. This aqueous solution was applied onto a PET film to a dry film thickness of 2 microns, and the temperature was 15.
It was crosslinked and cured at 0°C for 30 seconds. The physical properties of this cured film were almost the same as in Example 1 above.

[0018]

Effects of the Invention The conductive film-forming composition of the present invention is composed of an aqueous composition containing a water-soluble ion conductive resin and a thermally crosslinkable monomer in a predetermined range. By applying the product to the surface of the object to be coated, preferably in the presence of a crosslinking curing agent, and heating it, it can be crosslinked and cured to easily obtain an electrically conductive cured film. The coating film formed by this conductive coating film-forming composition is transparent, has excellent water resistance and solvent resistance, and has a surface resistance value of approximately 107 ohms/square at 50%RH humidity. It has outstanding conductive performance. This conductive film-forming composition is an aqueous composition that uses water as a solvent, so it is extremely safe to handle, and the film is formed by cross-linking and curing the film simply by heating. Therefore, there is no need to use complicated operations or excessive equipment, such as the formation of a conductive coating film using ultraviolet irradiation, as described above.
Combined with its outstanding conductive performance, it has great practical value.

Claims (2)

[Claims] Claim 1: Water-soluble ion conductive resin (A)
A composition for forming a conductive coating film, comprising an aqueous composition containing 0 to 97% by weight and a thermally crosslinkable monomer (B) in a range of 3 to 30% by weight. [Claim 2] The water-soluble ion conductive resin (A)
has a cationic quaternary ammonium base in the side chain,
A water-soluble copolymer made by copolymerizing a monofunctional vinyl monomer with a polymerizable double bond at the end, a monofunctional vinyl monomer with a hydroxyl group, and another polymerizable vinyl monomer. The composition for forming a conductive coating film according to claim 1, characterized in that
3. The composition for forming a conductive coating film according to claim 1, wherein the thermally crosslinkable monomer (B) is an epoxy compound having 2 to 4 glycidyl groups.