JP5352638B2 - Method for producing conductive paint and method for forming conductive coating film using the conductive paint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for industrially and economically advantageously forming a coating film having excellent conductivity, and to provide a conductive coating material to be used in the method. <P>SOLUTION: This conductive coating material is composed of a first liquid containing a conductive oxide but substantially not containing a curable component, and a second liquid containing a curable component, where in the first liquid, water and a non-aqueous solvent such as N-methylformamide, dimethylsulfoxide, ethylene glycol, 4-butyrolactone, acetamide and 1,3-dimethyl-2-imidazolidinone are formulated as the dispersant. After forming a layer containing the conductive oxide by applying the first liquid on a substrate, the second liquid is applied thereon and the curable component is cured to form the conductive coating film. This invention can simply impart excellent conductivity to the substrate. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a conductive paint and a method for forming a conductive coating film using the same, and more particularly to a method for forming a conductive coating film having high conductivity and transparency and having an antistatic effect.

  Various transparent substrates such as display surfaces of display devices such as cathode ray tubes, liquid crystal displays, window materials for clean rooms, plastics and glass used as packaging materials for electronic components, or films used for overhead displays and photographs, Generally, it is an insulator and is easily charged with static electricity. For this reason, dust and dirt are likely to adhere to the surface, and electronic devices and the like may cause malfunction.

  Therefore, in order to prevent electrification, conductive oxides such as tin oxide, indium oxide, and zinc oxide are usually deposited by sputtering or applied to a coating agent or paint. Among these conductive oxides, those having fine particles, for example, spherical particles having an average particle size of 0.1 μm or less, have the property of transmitting visible light, so that the transparent group as described above is used. Suitable for use on materials. However, vapor deposition requires a large-scale apparatus, is not suitable for mass production, and is a high-cost method. In the method of applying a coating agent or paint, the curable component compounded therein is insulative, so it is high. There was a problem that conductivity could not be obtained.

  The present invention solves the problems of the prior art described above, and provides a method for forming a coating film having excellent conductivity in an industrially and economically advantageous manner and a conductive paint used in the method.

  As a result of intensive research, the inventor of the present invention 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 substantially does not contain a curable component, On the other hand, when a second liquid containing a curable component is included in the second liquid, and after applying the first liquid containing the conductive oxide, the second liquid containing the curable component is applied and cured. The inventors have found that a coating film having excellent conductivity can be easily obtained and completed the present invention.

  That is, the present invention is a conductive paint comprising a conductive oxide, water, a first liquid containing a non-aqueous solvent having a relative dielectric constant of 35 or higher and a boiling point of 100 ° C. or higher, and a second liquid containing a curable component. is there. The present invention also provides a conductive coating film in which the first liquid of the conductive coating 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. It is the formation method. Furthermore, in the present invention, the first liquid of the conductive paint is applied to the surface of the article to form a layer containing a conductive oxide, and then the second liquid is applied thereon to cure the curable component. A method for producing an article having a conductive coating film.

  The present invention relates to a two-component conductive material comprising a conductive oxide, water, a first liquid containing a non-aqueous solvent having a relative dielectric constant of 35 or higher and a boiling point of 100 ° C. or higher, and a second liquid containing a curable component. After applying the first liquid compounded with conductive oxide and applying the second liquid compounded with a curable component, it is insulative at the contact point between the conductive oxide and the substrate. It is presumed that the curable component is difficult to intervene, and aggregation of the conductive oxide can be prevented, so that excellent conductivity can be easily imparted to the substrate. This coating method is industrially and economically advantageous compared to the vapor deposition method, and also has high coating film hardness, so that the two-component conductive paint of the present invention imparts conductivity to various substrates. It can be used as an electrical conductivity imparting agent for general households as well as industrial applications for producing articles having a conductive coating film. Furthermore, when conductive oxide fine particles are used, a coating film having excellent transparency and conductivity can be obtained, and thus it is particularly useful as an antistatic material for transparent substrates such as glass, plastics, and films. .

  The conductive paint of the present invention is composed of a first liquid that contains a conductive oxide and substantially does not contain a curable component, and a second liquid that contains a curable component. Since the conductive oxide compounded in the first liquid is generally hydrophilic, the conductive oxide is dispersed and stabilized when an organic solvent is used as the dispersion medium in the composition of the first liquid that does not contain a curable component. In order to achieve this, it is necessary to add a surfactant or to treat a coupling agent. However, since the surfactant and the coupling agent are insulative, they cause a decrease in conductivity. On the other hand, when water is used as the dispersion medium of the first liquid, the dispersion can be stabilized by adjusting to a specific pH. However, since water has a large surface tension, the conductive oxide tends to aggregate when evaporating. Conductivity and transparency cannot be obtained. For this reason, in the present invention, by using water, a non-aqueous solvent having a relative dielectric constant of 35 or higher and a boiling point of 100 ° C. or higher as the first liquid dispersion medium containing the conductive oxide, It 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 later to form a layer containing a conductive oxide, the second liquid is applied to cure the curable component to form a coating film. A highly conductive coating film is obtained. This is presumed to be because an insulating curable component is unlikely to intervene at the contact point between the conductive oxide and the substrate, and a conductive path is easily formed.

  As the non-aqueous solvent to be blended in the first liquid, the relative dielectric constant may be 35 or more as described above, more preferably in the range of 35 to 200, and the boiling point may be 100 ° C. or more. The thing of the range of 100-250 degreeC is more preferable. As such a non-aqueous solvent, N-methylformamide (dielectric constant 190, boiling point 197 ° C.), dimethyl sulfoxide (relative dielectric constant 45, boiling point 189 ° C.), ethylene glycol (relative dielectric constant 38, boiling point 226 ° C.), 4-butyrolactone (relative permittivity 39, boiling point 204 ° C.), acetamide (relative permittivity 65, boiling point 222 ° C.), 1,3-dimethyl-2-imidazolidinone (relative permittivity 38, boiling point 226 ° C.), formamide ( Specific dielectric constant 111, boiling point 210 ° C.), N-methylacetamide (relative dielectric constant 175, boiling point 205 ° C.), furfural (relative dielectric constant 40, boiling point 161 ° C.) and the like. Can be used. The content of the non-aqueous solvent is preferably in the range of 0.15 to 20 parts by weight, more preferably 0.15 to 15 parts by weight with respect to 1 part by weight of water contained in the first liquid.

Further, if the surface tension of the non-aqueous solvent is small, unevenness in the coating film hardly occurs, and smoothness with less wrinkles and wrinkles is excellent, which is preferable, and a surface tension of 50 × 10 ⁻³ N / m or less is preferable. more preferably those having, particularly preferably in the range of ^{10 × 10 -3 ~50 × 10 -3} N / m. As such, 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 × 10 ⁻³ N / m) and the like.

As the conductive oxide to be blended in the first liquid, known ones can be used, for example, tin oxide, indium oxide, zinc oxide, etc., and one or more of these can be used. The conductive oxide may be doped with one or more different elements such as Sb, F, W, Ga, Sn, In, and Al for the purpose of further increasing the conductivity, and in particular tin oxide. And a combination of Sb, F or W, indium oxide and Sn, zinc oxide and F, Al, Ga, In or Sb is particularly preferable. Furthermore, for the purpose of improving dispersibility, the surface of the conductive oxide can be coated with an oxide such as Si, W, Zr, Al or a hydrated oxide. The shape of the conductive oxide is not particularly limited, such as a spherical shape, a needle shape, a resin shape, or a 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. Although the compounding quantity of an electroconductive oxide can be set suitably, it is preferable to contain in the range of 0.5-50 weight% in the 1st liquid, and 0.5-20 weight% is more preferable.

  The conductive oxide has the property of being dispersed and stabilized 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, the first liquid of the conductive paint of the present invention is preferably prepared by adjusting the pH of water according to the isoelectric point of the conductive oxide used and dispersing the conductive oxide in this water. The first liquid is prepared by adding the non-aqueous solvent to the liquid in which the product is dispersed. Other additives, solvents and the like may be appropriately added to the first liquid. For dispersing the conductive oxide, a dispersing machine such as a sand mill, a line mill, or a colloid mill may be used as necessary. Examples of basic compounds used for pH adjustment include alkali metal or alkaline earth metal hydroxides such as sodium hydroxide, potassium hydroxide, and calcium hydroxide, ammonium compounds such as ammonia, and amines as acidic compounds. Examples thereof include inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid, and organic acids such as formic acid, acetic acid and propionic acid.

  As the curable component to be blended with the second liquid, inorganic materials such as alkyl silicate and alkyl titanate, and organic materials such as acrylic, alkyd, polyester, urethane and epoxy can be used. Any of ultraviolet curing type and the like may be used. The compounding quantity of a sclerosing | hardenable component can be set suitably.

  The first liquid and the second liquid contain fillers such as colloidal silica and fine particle titanium oxide, various additives, and colorants as long as the conductivity and transparency are not impaired in addition to the above components. In addition, solvents such as alcohols, ketones, esters, aromatics, and aliphatics may be contained.

In order to form a conductive coating film using the two-component conductive paint of the present invention, first, spin coating, dip coating, bar coating, spray coating, etc. are applied to the base material using the first liquid containing a conductive oxide. After applying the above method to form a layer containing a conductive oxide on the surface of the base material, the second liquid is applied by the same method, and heated and dried to cure the curable component and become conductive. An oxide is fixed and a conductive coating film is formed on the surface of the substrate. The conductive coating film thus obtained has a surface resistance of, for example, 1 × 10 ⁷ Ω / □ or less. Although there is no restriction | limiting in particular in the film thickness at the time of application | coating of a 1st liquid and a 2nd liquid, when workability | operativity and leveling property are considered, it is preferable to set it as the range of 0.01-10 micrometers in all. Using such a forming method, an article having a conductive coating film on the surface can be produced. Various articles can be targeted, for example, plastic products, film products, paper products, glass products, ceramic products, etc. Specifically, display devices such as cathode ray tubes and liquid crystal displays, clean rooms, etc. And window materials such as electronic parts, packaging materials such as electronic parts, overhead displays and films used for photographs.

  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-100P doped with antimony (manufactured by Ishihara Sangyo Co., Ltd .: specific surface area 70 m ² / g) was added to water to a concentration of 30% by weight, and the pH was adjusted with an aqueous sodium hydroxide solution. Was adjusted to 8 and then ground in a sand mill for 3 hours to obtain an SN-100P aqueous dispersion. Using this aqueous dispersion, the following formulation was mixed with a disper to obtain a two-component conductive paint of the present invention (sample A) consisting of a first liquid and a second liquid. In addition, 3 weight% of SN-100P is mix | blended with the 1st liquid, and the compounding quantity of acetamide is 0.24 weight part with respect to 1 weight part of water in a 1st liquid.

First liquid SN-100P aqueous dispersion 4.0 g
25.0 g of water
Ethylene glycol monobutyl ether 5.0 g
Acetamide 6.0 g

Second liquid methyl silicate 51 (manufactured by Colcoat Co.) 4.6 g
Ethanol 9.0 g
2-Propanol 46.8 g
1-methoxy-2-propanol 173.0 g
1.0 g of water
20% hydrochloric acid 0.03g

  Example 2 A two-component conductive paint (sample B) of the present invention was obtained in the same manner as in Example 1 except that acetamide was replaced with dimethyl sulfoxide.

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

  Example 4 A two-component conductive paint (sample D) of the present invention was obtained in the same manner as in Example 1 except that acetamide was replaced with ethylene glycol.

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

  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 paint (sample G) of the present invention was obtained in the same manner as in Example 1 except that the formulation of the first solution was changed to the following in Example 1. In addition, 3 weight% of SN-100P is mix | blended with the 1st liquid, and the compounding quantity of acetamide is 11 weight part with respect to 1 weight part of water in a 1st liquid.

First liquid SN-100P aqueous dispersion 4.0 g
1.0 g of water
Acetamide 12.0 g
N, N-dimethylformamide 12.0 g
2-Propanol 11.0 g

Comparative Example 1 In Example 1, except that acetamide was replaced with 1-butanol (relative dielectric constant 18, surface tension 25 × 10 ⁻³ N / m), the same procedure as in Example 1 was carried out. An aggregate of −100 P was formed, and no conductive paint was obtained.

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

SN-100P water dispersion 31.0 g
Methyl silicate 51 (manufactured by Colcoat Co.) 4.6 g
17.3 g of ethanol
2-propanol 3.3 g
1-methoxy-2-propanol 4.7 g
1.0 g of water
20% hydrochloric acid 0.03g

Comparative Example 3 Antimony-doped spherical tin oxide fine powder SN-100P (manufactured by Ishihara Sangyo Co., Ltd .: specific surface area 70 m ² / g) was added to ethanol to a concentration of 20% by weight, and further Dispersic as a dispersant. After adding 180 (manufactured by Big Chemie), an SN-100P ethanol dispersion was obtained by grinding with a sand mill for 3 hours. Using this ethanol dispersion, the following formulation was mixed with a disper to obtain a one-component conductive paint (sample I). The added amount of Dispersic 180 is 8 parts by weight with respect to 100 parts by weight of SN-100P.

SN-100P ethanol dispersion 47.0 g
Methyl silicate 51 (manufactured by Colcoat Co.) 4.6 g
Ethanol 1.0 g
2-propanol 3.3 g
1-methoxy-2-propanol 4.7 g
1.0 g of water
20% hydrochloric acid 0.03g

  Evaluation 1 A square glass substrate having a size of 75 mm and a thickness of 3 mm was set on a spin coater in the atmosphere at 50 ° C., and the two-component conductive paints (samples A to G) obtained in Examples 1 to 7 were used. After 1 ml of the first liquid was dropped, the conductive layer was applied by rotating at 120 rpm for 100 seconds. Then, the 2nd liquid was spin-coated on the same conditions, and it heated in 120 degreeC and 30 minutes in oven, and obtained the transparent conductive coating film. The one-component paints (samples H and I) obtained in Comparative Examples 2 and 3 were dropped onto the glass substrate, and then a transparent conductive coating film was obtained in the same manner as the two-component paint. The surface resistance of the obtained coating film was measured using a surface resistance meter (Loresta GP type, manufactured by Mitsubishi Chemical Corporation), and haze was measured using a haze meter (DH-300A type, manufactured by Nippon Denshoku Industries Co., Ltd.). Further, the pencil hardness of the coating film was measured in accordance with Japanese Industrial Standard (JIS K5400).

  Table 1 shows the results of surface resistance, haze, and pencil hardness. The two-component conductive paint of the present invention has excellent conductivity and transparency compared to a conventional one-component paint in which a conductive oxide and a curable component are dispersed in a dispersion medium. It can also be seen that an excellent coating film can be obtained. It has also been found that the conductive coating film formed using the two-component conductive paint of the present invention has a high coating film hardness and can be practically used.

  The present invention is useful as an antistatic material for transparent substrates such as glass, plastics and films.

Claims (4)

Including a conductive tin oxide, water and a nonaqueous solvent having a relative dielectric constant of 35 or more and a boiling point of 100 ° C. or more, the nonaqueous solvent is contained in a range of 0.15 to 20 parts by weight with respect to 1 part by weight of water. A method for producing a conductive paint comprising a first liquid and a second liquid containing a curable component, wherein conductive tin oxide is dispersed in water having a pH of at least 8 and then the non-aqueous solvent is added within the above range. A method for producing a conductive paint, comprising mixing at a blending amount to obtain at least a first liquid. The method for producing a conductive paint according to claim 1, wherein the non-aqueous solvent is at least one selected from 4-butyrolactone and 1,3-dimethyl-2-imidazolidinone. The first liquid of the conductive paint produced by the method according to claim 1 is applied to a substrate to form a layer containing conductive tin oxide, and then the second liquid is applied to cure the curable component. Method for forming a coating film. The first liquid of the conductive paint produced by the method according to claim 1 is applied to the surface of the article to form a layer containing conductive tin oxide, and then the second liquid is applied to cure the curable component. For producing an article having an adhesive coating.