JP2003020449A - Electroconductive coating material and method for forming electroconductive coated film using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for industrially and economically advantageously forming a coated film having excellent electroconductivity, and further to provide an electroconductive coating material usable in the method. SOLUTION: This electroconductive coating material is constituted of a first liquid containing an electroconductive oxide, and substantially free from a curing component, and a second liquid containing the curing component. The first liquid is obtained by formulating water as a disperser, and a nonaqueous solvent such as N-methylformide, dimethylsulfoxide, ethylene glycol, 4-butyrolactone, acetamide and 1,3-dimethyl-2-imidazolidinone, with the oxide. The electroconductive coated film is formed by coating the first liquid on a base material to form a layer containing the electroconductive oxide, and coating the second liquid on the resultant layer to cure the curable component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive coating material and a method for forming a conductive coating film using the same, and particularly to forming a conductive coating film having high conductivity and transparency and having an antistatic effect. Regarding the method.

[0002]

2. Description of the Prior Art Plastics and glass used for display surfaces of display devices such as cathode ray tubes and liquid crystal displays, window materials in clean rooms, packaging materials for electronic parts, and various transparent materials such as films used for overhead displays and photographs. The conductive substrate is generally an insulator and is easily charged with static electricity. For this reason, dust or dirt is likely to adhere to the surface, and the electronic device or the like may malfunction.

Therefore, in order to prevent electrification, it is usual to deposit a conductive oxide such as tin oxide, indium oxide or zinc oxide by sputtering or to mix it with a coating agent or paint and apply it. ing. Among these conductive oxides, fine particles, for example, spherical particles having an average particle diameter of 0.1 μm or less have a property of transmitting visible light, and therefore, the transparent group as described above is used. Suitable for use in wood. However, vapor deposition requires a large-scale device, is not suitable for mass production, and is a high-cost method. In the method of applying a coating agent or paint, since the curable component blended with it is insulative, it is expensive. There is a problem that conductivity cannot be obtained.

[0004]

SUMMARY OF THE INVENTION The present invention solves the problems of the prior art described above, and industrially and economically forms a coating film having excellent electroconductivity and the electroconductivity used for the method. The present invention provides a conductive paint.

[0005]

Means for Solving the Problems As a result of intensive studies by the present inventors, the first liquid contains a conductive oxide, water as a dispersion medium, a non-aqueous solvent having a high relative dielectric constant and a high boiling point, and The second liquid is a two-component conductive paint that does not contain a curable component, and the second liquid contains a curable component. The present invention has been completed by finding that a coating film having excellent conductivity can be easily obtained by applying and curing two liquids.

That is, the present invention is a conductive liquid comprising a conductive oxide, a first liquid containing water and a non-aqueous solvent having a relative dielectric constant of 35 or more and a boiling point of 100 ° C. or more, and a second liquid containing a curable component. It is a paint. In addition, the present invention is a conductive coating film in which the first liquid of the conductive coating material is applied to a substrate to form a layer containing a conductive oxide, and then the second liquid is applied to cure the curable component. Is a method of forming. Furthermore, the present invention applies the first liquid of the above-mentioned conductive paint to the surface of an article to form a layer containing a conductive oxide, and then applies the second liquid thereon to cure the curable component. A method for producing an article having a conductive coating film.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The conductive coating material of the present invention comprises a first liquid containing a conductive oxide and containing substantially no curable component, and a second liquid containing a curable component. . Since the conductive oxide compounded in the first liquid is generally hydrophilic, when an organic solvent is used as a dispersion medium in the composition of the first liquid containing no curable component, the conductive oxide is dispersed and stabilized. To do so, it is necessary to add a surfactant or treat the coupling agent. However, since the surface active agent and the coupling agent are insulative, they become a factor to reduce the conductivity. On the other hand, when water is used as the dispersion medium of the first liquid, the dispersion can be stabilized by adjusting it to a specific pH. However, since the surface tension of water is large, the conductive oxide easily aggregates when evaporated, which is desirable. The conductivity and transparency of can not be obtained. For this reason, in the present invention, by using water and a non-aqueous solvent having a relative dielectric constant of 35 or more and a boiling point of 100 ° C. or more as a dispersion medium of the first liquid in which the conductive oxide is mixed, The present invention is intended to stabilize the dispersion of the conductive oxide and prevent aggregation when the first liquid containing the conductive oxide is applied. When such a first liquid is applied to a substrate according to the method described below to form a layer containing a conductive oxide, a second liquid is applied to cure a curable component to form a coating film, which is excellent. A coating film having excellent conductivity is obtained. It is presumed that this is because it is difficult for an insulative curable component to intervene at the contact point between the conductive oxide and the base material, and a conductive path is easily formed.

As the non-aqueous solvent to be mixed with the first liquid, the relative dielectric constant may be 35 or more as described above, but 35 to 2
The range of 00 is more preferable, and the boiling point may be 100 ° C. or higher, but the range of 100 to 250 ° C. is more preferable. Such non-aqueous solvents include N-methylformamide (relative permittivity 190, boiling point 197 ° C.), dimethyl sulfoxide (relative permittivity 45, boiling point 189 ° C.), ethylene glycol (relative permittivity 38, boiling point 226 ° C.), 4-
Butyrolactone (dielectric constant 39, boiling point 204 ° C), acetamide (dielectric constant 65, boiling point 222 ° C), 1,3-dimethyl-2-imidazolidinone (dielectric constant 38, boiling point 2)
26 ° C), formamide (relative dielectric constant 111, boiling point 210)
C), N-methylacetamide (relative permittivity 175, boiling point 205 ° C.), furfural (relative permittivity 40, boiling point 161)
C.) and the like, and one or more of these may be used. The content of the non-aqueous solvent is preferably 0.15 to 20 parts by weight, and more preferably 0.15 to 15 parts by weight, with respect to 1 part by weight of water contained in the first liquid.

When the surface tension of the non-aqueous solvent is small, unevenness is less likely to occur in the coating film and the smoothness with less wrinkles and creases is excellent, which is preferable. 50 × 10 ⁻³ N
It is more preferable that the surface tension is less than 10 m / m.
In the range of ^{× 10 -3 ~50 × 10 -3 N} / m are particularly preferred. Examples thereof include N-methylformamide (surface tension 38 × 10 ⁻³ N / m), dimethyl sulfoxide (surface tension 43 × 10 ⁻³ N / m), ethylene glycol (surface tension 48 × 10 ⁻³ N). / M), 4-
Butyrolactone (surface tension 44 × 10 ⁻³ N / m), acetamide (surface tension 39 × 10 ⁻³ N / m), 1,3
-Dimethyl-2-imidazolidinone (surface tension 41 x 1
0 ^-3 N / m), and the like.

Known conductive oxides can be used in the first liquid, and examples thereof include tin oxide, indium oxide and zinc oxide, and one or more of these can be used. . The conductive oxide may be Sb, F, W, Ga, Sn, In, A for the purpose of further increasing the conductivity.
One or two or more different elements such as l may be doped, and among them, tin oxide and Sb, F or W, indium oxide and Sn, zinc oxide and F, Al, Ga, In or Sb. Combinations are especially preferred. Further, for the purpose of improving dispersibility, the surface of the conductive oxide can be coated with an oxide or hydrated oxide of Si, W, Zr, Al or the like. The shape of the conductive oxide is not particularly limited, such as spherical shape, needle shape, resin shape, and plate shape. Range 20~150m ² / g, since preferably conductive oxide having a specific surface area in the range of 30~130m ² / g is excellent in transparency, and the surface energy is not too dispersion is relatively easy, It is preferable to use this. The blending amount of the conductive oxide can be appropriately set,
The first liquid is preferably contained in the range of 0.5 to 50% by weight, more preferably 0.5 to 20% by weight.

The conductive oxide has a property of stabilizing dispersion in alkaline water when the isoelectric point is in the acidic region, and in acidic water when the isoelectric point is in the alkaline region. Therefore, it is preferable that the first liquid of the conductive coating material of the present invention adjusts the pH of water according to the isoelectric point of the conductive oxide used and disperses the conductive oxide in this water. The first liquid is prepared by adding the non-aqueous solvent to the liquid in which the substance is dispersed. Other additives, solvents and the like may be added to the first liquid as appropriate. A dispersing machine such as a sand mill, a line mill or a colloid mill may be used for dispersing the conductive oxide, if necessary. As the basic compound used for pH adjustment,
For example, alkali metal or alkaline earth metal hydroxides such as sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonium compounds such as ammonia, amines, etc., and acidic compounds such as hydrochloric acid, sulfuric acid, nitric acid, etc. Examples thereof include acids and organic acids such as formic acid, acetic acid, and propionic acid.

As the curable component to be added to the second liquid, an inorganic type such as alkyl silicate or alkyl titanate or an organic type such as acrylic, alkyd, polyester, urethane or epoxy can be used. Any of bake-curing type and ultraviolet-curing type may be used. The compounding amount of the curable component can be set appropriately.

In addition to the above-mentioned components, the above-mentioned first and second liquids contain a filler such as colloidal silica and fine particles of titanium oxide, various additives, and a coloring agent as long as the conductivity and the transparency are not impaired. It may be contained, and may also contain solvents such as alcohols, ketones, esters, aromatics and aliphatics.

In order to form a conductive coating film using the two-component conductive coating material of the present invention, first, a first liquid containing a conductive oxide is spin-coated, dip-coated, bar-coated, on a substrate. After applying a method such as spray coating to form a layer containing a conductive oxide on the surface of the base material, apply the second liquid in the same way and heat and dry to cure the curable component. Then, the conductive oxide is fixed and a conductive coating film is formed on the surface of the base material. The conductive coating film thus obtained has a surface resistance of 1 × 10 ⁷ Ω / □ or less, for example. There is no particular limitation on the film thickness of the first liquid and the second liquid when applied, but in consideration of workability and leveling property, both are 0.01 to
The range is preferably 10 μm. By using such a forming method, an article having a conductive coating film on its surface can be manufactured. As the article, various things can be targeted, for example, plastic products, film products, paper products, glass products, ceramic products, etc.,
Specific examples include cathode ray tubes, display devices such as liquid crystal displays, window materials for clean rooms, packaging materials for electronic components, films used for overhead displays and photographs, and the like.

[0015]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 Spherical tin oxide fine powder SN-10 doped with antimony
0P (manufactured by Ishihara Sangyo Co., Ltd .: specific surface area 70 m ² / g) was added to water so that the concentration was 30% by weight, and the pH was adjusted to 8 with an aqueous sodium hydroxide solution, followed by grinding with a sand mill for 3 hours. Thus, an aqueous dispersion of SN-100P was obtained.
Using this aqueous dispersion, the following formulation was mixed with a disper to obtain a two-component conductive coating material (Sample A) of the present invention consisting of a first liquid and a second liquid. 3% by weight of SN-100P was mixed in the first liquid, and the amount of acetamide was 0.24 parts by weight with respect to 1 part by weight of water in the first liquid.

[0017] First liquid SN-100P aqueous dispersion 4.0 g Water 25.0 g Ethylene glycol monobutyl ether 5.0 g Acetamide 6.0 g

[0018] Second liquid Methyl silicate 51 (made by Colcoat) 4.6 g Ethanol 9.0 g 2-propanol 46.8 g 1-methoxy-2-propanol 173.0 g Water 1.0 g 20% hydrochloric acid 0.03 g

Example 2 A two-component conductive coating material of the present invention (Sample B) was obtained in the same manner as in Example 1 except that dimethyl sulfoxide was used instead of acetamide.

Example 3 A two-component conductive coating material of the present invention (Sample C) was obtained in the same manner as in Example 1 except that N-methylformamide was used instead of acetamide.

Example 4 A two-component conductive coating material (Sample D) of the present invention was obtained in the same manner as in Example 1 except that ethylene glycol was used instead of acetamide.

Example 5 In Example 1, acetamide was replaced with 1,3-dimethyl-
A two-component conductive coating material of the present invention (Sample E) was obtained in the same manner as in Example 1 except that 2-imidazolidinone was used.

Example 6 A two-component conductive coating material (Sample F) of the present invention was obtained in the same manner as in Example 1 except that acetamide was replaced with 4-butyrolactone.

Example 7 A two-component conductive coating material of the present invention (Sample G) was obtained in the same manner as in Example 1 except that the formulation of the first liquid was changed to the following. . SN-100 was used as the first liquid.
3% by weight of P is added to 1 part by weight of water in the first liquid,
The compounding amount of acetamide is 11 parts by weight.

[0025] First liquid SN-100P aqueous dispersion 4.0 g Water 1.0 g Acetamide 12.0 g N, N-dimethylformamide 12.0 g 2-propanol 11.0 g

Comparative Example 1 The same procedure as in Example 1 was repeated except that the acetamide was replaced with 1-butanol (relative permittivity: 18, surface tension: 25 × 10 ⁻³ N / m). SN for liquid
Aggregates of -100P were formed, and a conductive paint could not be obtained.

Comparative Example 2 Using the aqueous dispersion of SN-100P of Example 1, the following formulation was mixed with a disper to obtain a one-component conductive paint (Sample H).

[0028] SN-100P aqueous dispersion 31.0 g Methyl silicate 51 (made by Colcoat) 4.6 g Ethanol 17.3 g 2-propanol 3.3 g 1-methoxy-2-propanol 4.7 g Water 1.0 g 20% hydrochloric acid 0.03 g

Comparative Example 3 Spherical tin oxide fine powder SN-10 doped with antimony
0P (manufactured by Ishihara Sangyo Co., Ltd .: specific surface area 70 m ² / g) was added to ethanol so that the concentration became 20% by weight, and Disperbic 180 (manufactured by Big Chemie) was further added as a dispersant, followed by a sand mill. By crushing for 3 hours, an ethanol dispersion of SN-100P was obtained. Using this ethanol dispersion, the following formulations were mixed with a disper to obtain a one-component conductive paint (Sample I). In addition, the addition amount of Disperbic 180 is 8 parts by weight with respect to 100 parts by weight of SN-100P.

[0030] SN-100P ethanol dispersion 47.0 g Methyl silicate 51 (made by Colcoat) 4.6 g Ethanol 1.0 g 2-propanol 3.3 g 1-methoxy-2-propanol 4.7 g Water 1.0 g 20% hydrochloric acid 0.03 g

Evaluation 1 A square glass substrate with a piece of 75 mm and a thickness of 3 mm was set to 5
Example 1 was set in a spin coater in the atmosphere of 0 ° C.
After dropping 1 ml of the first liquid of the two-component conductive coating material (Samples A to G) obtained in Nos. 7 to 100 at 120 rpm.
The conductive layer was applied by rotating for 2 seconds. After that, spin coat the second liquid under the same conditions, and place in an oven for 120
A transparent conductive coating film was obtained by heating at 30 ° C. for 30 minutes. Also,
The one-pack paints (Samples H and I) obtained in Comparative Examples 2 and 3 were
After dropping onto the glass substrate, a transparent conductive coating film was obtained in the same manner as the two-component coating material. The surface resistance of the obtained coating film was measured using a surface resistance meter (Loresta GP type, manufactured by Mitsubishi Chemical Co., Ltd.), and the haze was measured using a haze meter (DH-300A type, manufactured by Nippon Denshoku Industries Co., Ltd.). The pencil hardness of the coating film was measured according to Japanese Industrial Standards (JIS K5400).

The results of surface resistance, haze and pencil hardness are shown in Table 1.
Shown in. The two-component conductive coating material of the present invention is very excellent in conductivity as compared with a conventional one-component coating material in which a conductive oxide and a curable component are dispersed in a dispersion medium, and also has transparency. It can be seen that an excellent coating film can be obtained. It was also found that the conductive coating film formed using the two-component conductive coating material of the present invention has a high coating hardness and is at a level that can be practically used.

[0033]

[Table 1]

[0034]

The present invention comprises a conductive oxide, a first liquid containing water and a non-aqueous solvent having a relative dielectric constant of 35 or more and a boiling point of 100 ° C. or more, and a second liquid containing a curable component. It is a two-component conductive paint, and after applying the first liquid containing a conductive oxide, and then curing by applying a second liquid containing a curable component, a conductive oxide and a base material are obtained. It is presumed that the insulative curable component is unlikely to intervene at the contact point, and the conductive oxide can be prevented from aggregating, so that excellent conductivity can be easily imparted to the base material. This coating method is industrially and economically advantageous as compared with the vapor deposition method, and since the coating film hardness is high, the two-component conductive coating material of the present invention can impart conductivity to various base materials. In addition to industrial use for producing an article having a conductive coating film, it can also be used as a general household electrical conductivity imparting agent. Furthermore, when conductive oxide fine particles are used, a coating film having excellent transparency and conductivity can be obtained, so that it is particularly useful as an antistatic material for transparent base materials such as glass, plastics and films. .

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01B 13/00 503 H01B 13/00 503Z F term (reference) 4D075 AE03 BB26Z CA02 CA13 CA22 CB06 DA04 DA06 DA23 DB13 DB14 DB18 DB31 DC01 DC24 DC36 EA06 EA07 EA10 EB22 EB33 EB35 EB36 EB38 EB43 EC02 EC30 EC51 EC52 EC60 4J038 CG001 DB001 DD001 DD121 DG001 DL021 DM021 HA066 KA06 NA20 PA07 5G301 DA02 DA15 DA25 DA53 DA57 DA59 A60 DD02 5

Claims (10)

[Claims] 1. A first liquid containing a conductive oxide, water, a non-aqueous solvent having a relative dielectric constant of 35 or more and a boiling point of 100 ° C. or more, and a second liquid containing a curable component. Conductive paint that does. 2. The conductive paint according to claim 1, wherein the non-aqueous solvent has a surface tension of 50 × 10 ⁻³ N / m or less. 3. The non-aqueous solvent is at least one selected from N-methylformamide, dimethylsulfoxide, ethylene glycol, 4-butyrolactone, acetamide, and 1,3-dimethyl-2-imidazolidinone.
The conductive paint described. 4. One part by weight of water contained in the first liquid is 0.
The conductive paint according to claim 1, which contains a non-aqueous solvent in the range of 15 to 20 parts by weight. 5. The conductive paint according to claim 1, wherein the conductive oxide has a specific surface area in the range of ²⁰ to 150 m ² / g. 6. The conductive paint according to claim 1, wherein the conductive oxide is at least one selected from tin oxide, indium oxide and zinc oxide. 7. The conductive oxide is Sb, F, W, Ga, S
The conductive paint according to claim 6, which is doped with at least one element selected from n, In and Al. 8. The conductive paint according to claim 1, wherein the curable component is at least one selected from alkyl silicates, alkyl titanates, acrylic resins, alkyd resins, polyester resins, urethane resins and epoxy resins. 9. A first liquid of the conductive paint according to claim 1 is applied to a substrate to form a layer containing a conductive oxide, and then a second liquid is applied. A method for forming a conductive coating film, which cures a curable component. 10. The first liquid of the conductive coating composition according to claim 1 is applied to the surface of an article to form a layer containing a conductive oxide, and then a second layer is formed thereon. A method for producing an article having a conductive coating film, which comprises applying a liquid to cure a curable component.