JPS6335668A - Production of electrically conductive paint - Google Patents

Abstract

PURPOSE:To produce an electrically conductive paint capable of forming a coating film having excellent electrical conductivity and transparency on a substrate such as glass, by dissolving or dispersing electrically conductive fine powder prepd. from an Sn compd. or an In compd. and a binder resin in a solvent. CONSTITUTION:While an aq. soln. of a tin compd. or an indium compd. is kept at a pH of 8-12, said compd. is gradually hydrolyzed to form a sol contg. colloidal particles. The sol is dried, fired and crushed. The resulting electrically conductive fine powder (A) and a binder resin (B) are dissolved or dispersed in a solvent to obtain an electrically conductive paint. According to the above method, electrically conductive fine powder having an average particle size of not larger than 0.4mu in the paint and a sharp particle size distribution can be obtd. The paint contg. the fine particles has excellent surface smoothness and contains only a small amount of coarse particles having a particle size of not larger than 0.8mu so that it has excellent transparency.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for producing a conductive coating material, and more particularly to a method for producing a conductive coating material capable of forming a conductive coating film with excellent transparency.

Technical aspects of the invention and its problems In recent years, prevention of static electricity on transparent substrates such as glass or plastics has been increasingly attempted by imparting conductivity to the substrates.

Conventionally, in order to impart conductivity to a base material, the surface of the base material is coated with a paint that is made conductive by mixing carbon fibers, metal fibers, carbon fibers, or metal fibers. has been carried out. However, with this paint, the paint film is gray and [
J. Since it is black, there was a problem that the color tone of the single material was 11. This is carbon disguise,
At the end of the metal (cedar), the carbon fiber or metal fiber itself absorbs light.

In addition, in order to impart conductivity to the base material, 71 coats the surface of the base material with a conductive paint made by dispersing or dissolving conductive powder and binder resin in a solvent to form a conductive coating. The method of forming the structure has fluctuated widely.

In order to form conductive coatings with excellent clarity, tin oxide, indium oxide, and the like have been used as conductive materials.

However, when trying to form a clear conductive paint film using conductive particles such as tin oxide and indium oxide as conductive powder, the problem is that the transparency is not necessarily satisfactory. was necessary.

In order to solve the problems associated with the transparency of such a transparent conductive coating film, for example, IS Publication No. 61-9343 discloses that it is made of tin oxide containing antimony and has an average particle size that is visible to visible light. An electrically conductive paint using a powder having a conductivity of 0.2 μm or less, which is smaller than the wavelength of

However, in the conductive paint disclosed in Japanese Patent Publication No. 61-9343, an aqueous solution in which a specific amount of tin chloride and antimony chloride are dissolved is poured into heated water to hydrolyze the chloride, and the precipitate is precipitated. After filtering and washing, 11
Since conductive powder with a diameter of 0.2 μm or less is produced by oral heat treatment, the following problems have arisen. However, as disclosed in the above-mentioned publication, when a precursor of conductive fine powder is precipitated in a liquid by hydrolyzing a halide, the precipitate is an agglomeration of extremely fine primary particles. is. Therefore, after filtering and washing the precipitate, the fine powder obtained by heat treatment is generally broad in particle size due to sintering of secondary particles.

Therefore, when mixing and dispersing conductive fine powder into plastics or paints, it is necessary to crush and cover the sintered fine powder in order to make the mixing and dispersion uniform. However, the conductive fine powder produced through the above-mentioned precipitation process before heat treatment has an extremely small particle size and high surface activity, so the bond between particles is strong and sintering occurs during heat treatment. is progressing, and the above-mentioned pulverization is not necessarily easy. In addition, even if the average particle size is reduced by pulverization, it is not possible to obtain conductive particles with a sharp particle size (i5), and since particles inherently have strong cohesive force, it is difficult to obtain conductive particles that have a sharp particle size. There was a problem in that a relatively large amount of surfactant had to be used to prevent agglomeration.

Purpose of the Invention The present invention is intended to solve the above-mentioned problems associated with the prior art, and it is necessary to form a conductive and transparent coating film on a substrate such as glass or plastic. It is an object of the present invention to provide a method for manufacturing such a conductive coating A'31.

Summary of the Invention The method for producing a conductive paint according to the present invention comprises (a) adding an aqueous solution of a tin compound or an indium compound to 8 to 12 p.p.
A sol containing colloidal particles is generated by gradually hydrolyzing the compounds in the liquid by holding it under H conditions,
Next, this sol is dried, fired, and then pulverized to obtain a conductive fine powder, and (b) a binder resin, which is then dissolved or dispersed in a solvent.

According to the method for producing a conductive paint according to the present invention, conductive fine particles having an average particle size of 0.4 μm or less and a sharp particle size distribution in the paint can be obtained, and conductive particles containing the conductive fine particles can be obtained. Paints have excellent surface smoothness and contain only a small amount of coarse particles of 0.8 μm or more, so their transparency is also lacking.

DETAILED DESCRIPTION OF THE INVENTION The method for producing the conductive +1 paint according to the present invention will be specifically described below.

The method for producing a conductive paint according to the present invention includes dissolving (a) conductive paint (1'l') end and (b) binder) wound fat in a solvent. -Or it is characterized by avoiding dispersion.

First, to explain the method for preparing this electrically conductive [1] fine powder, this (a) 4-electrically conductive powder is prepared by maintaining an aqueous solution of a tin compound or an indium compound under pt1 conditions of 8 to 12. A sol containing colloidal particles is produced by gradually hydrolyzing the compound, and this sol is then dried, processed, calcined, and then pulverized.

As a starting material, a tin compound or an indium compound that is water-soluble and can be hydrolyzed within a pH range of 8-12 is used, specifically, a tin compound such as potassium stannate, sodium stannate, or indium nitrate. , indium compounds such as indium sulfate can be used.

When the metal species contained in the aqueous solution of a tin compound or indium compound (hereinafter referred to as raw material liquid) is either tin or indium, the resulting fine powder is tin oxide or indium oxide, respectively. However, by dissolving a small amount of different metals in the raw material liquid, conductive fine powder doped with different metals can be produced.

For example, by dissolving a small amount of tartarite (potassium antimonyl tartrate) or ammonium fluoride in a raw material liquid containing a tin compound, a conductive material in which antimony or fluorine is doped with soot' oxide is used. 1n of fine powder
It can be added to the raw material liquid containing the indium compound.
By dissolving a small amount of a tin compound, a conductive fine powder in which indium oxide is doped with tin can be obtained.

The conductive fine powder doped with a different metal can also be obtained by impregnating the tin oxide or indium oxide obtained as described above with an aqueous solution containing a compound of a different metal and then firing it. Can be done.

The concentration of the tin compound or indium compound contained in the raw material liquid can be arbitrarily selected, but it is generally preferred that it be in the range of 5 to 30%.

The tin compound or indium compound contained in the above raw stone liquid is mixed with a different metal compound as a dopant when the compound of a different metal is coexisting with DI-18~
During the hydrolysis reaction, I)H in the reaction system must always be maintained in the range of 8 to 12. If the pH of the reaction system is less than D1-18, the particle size of the resulting conductive fine particles will be broad; Metal hydroxides are undesirable because they precipitate and cannot be dissolved in the liquid as colloidal particles, making it impossible to prepare a sol. On the other hand, if the pH of the reaction system exceeds 12, although it is not impossible to prepare a sol, the alkaline content cannot be sufficiently removed when washing the colloid particles filtered from the sol, resulting in a
This is undesirable because it reduces the conductivity of the fine powder.

Therefore, when carrying out a hydrolysis reaction of a tin compound or an indium compound, specifically, pf-18 to pf-1
Prepare a reactor containing water in step 2, and if the raw material liquid is alkaline, feed the raw stone liquid and the acidic liquid at a rate that does not exceed l) H or D) 2 within the predetermined range in the reactor. It is preferable to gradually and slowly add the mixture to the reactor. Moreover, when the raw material liquid is acidic, it is preferable to pour the raw material liquid and the alkaline liquid into the reactor in the same manner as above. There is no particular limit to the solid content concentration of the sol solution produced in the reactor, and generally speaking, the higher the SL, the broader the distribution of the dispersion of the colloid particles produced.

The reaction temperature for hydrolysis can be arbitrarily selected usually within the range of 30-90'C.

By gradually hydrolyzing the raw material liquid under the conditions 1))-1 above, the tin or indium compound becomes colloidal particles consisting of a compound, a hydrous oxide, or a hydroxide, and these particles are used as a dispersoid. A sol solution is prepared.

In this case, if a dopant coexists in the raw stone liquid, it is considered to be a colloidal particle containing the dopant. The average particle size of the colloidal particles obtained by hydrolysis is 0.05~
0.3 μ, preferably in the range of 0.07 to 0.2 μ, and the particle size tri is usually 80% or more of the total particles - L is in the range of 0.5 times to 1.5 (g) of the average particle size. The average particle size of the colloidal particles can be controlled by changing the amount and feed rate of the raw material liquid supplied to the hydrolysis reaction system. The lower the temperature, the more the particle size distribution becomes V-shaped.

In addition, the slower the feed rate of the raw material liquid, the greater the growth of colloid particles can be avoided.

After preparing the sol solution, the sol 11 is reduced by 1 to collect colloidal particles, and the colloidal particles are washed to remove by-product salts and other substances adhering to the particles, and then dried.
By further firing and then pulverizing, a conductive fine powder can be obtained. The particles filtered from the sol are
Sintered to some extent during the firing process, the average particle size of the powder is 20 ~
Although it is about 50μ7n, the specific surface area of this powder is less than 50μ,·′3. On the other hand, 1'! is produced through a conventionally known precipitation and release process. 1) The final specific surface area is
70 to 100rrt/';i. This indicates that the 1q fine powder of the present invention is composed of larger primary particles than the conventional fine powder. The fine powder obtained in this way can also be easily released from its sintered state by crushing, and by using Tsutomi's crushing means, the average particle in the paint has a conductivity of about 0.2 to 0.4μ5. A fine powder can be obtained. The fine powder thus obtained contains only a small amount of coarse particles of, for example, 0.8 μm or more.

13. The pulverization of (a) conductive fine particles may be carried out before mixing with other components such as (b) a binder (such as a binder). It can also be carried out after mixing with other components.The conductive fine particles can be pulverized by conventional pulverization methods such as an attritor, sand mill, ball mill, three-roll mill, etc. Or available.

(1)) The binder resin used in the present invention includes:
Conventionally, conductive coating A'3 is widely used as a binder resin. Specifically, for example, vinyl chloride resin, m-acid vinyl resin, polynisdel (Anan), acrylic (1-fat), urethane-based, II + resin, epoxy-based resin, polycarbonate-based resin, melamine-based resin, butyral-based resin, polyimide resins, polysulfones (1), polyethersulfones (5)
Oil or ultraviolet curing resin is used. Furthermore, a mixture of the above resins or a military uniform combination of the above 11 and 4 resins can also be used.

The mixing ratio of the above (a) conductive fine powder and (b) binder, ) or 1 fat is such that (a) conductive fine powder is 40.-55% fat, preferably 60-90
It is preferred that an amount of Iffi% is used.

fa) If the amount of conductive fine particles is less than 40% by weight, the conductivity of the resulting coating film will be poor, while if it exceeds 96% by weight, the adhesion between the coating film and the substrate and the transparency of the resulting coating film will be reduced. This is not desirable because it worsens the

The method for producing a conductive paint according to the present invention is characterized by dissolving or dispersing each of the above components in a solvent. Specific examples include methyl ethyl ketone, methyl isobutyl ketone, toluene, cyclohegiline, isopropanol, n-
Butanol and the like can be used alone or in combination. This drug is a coating film of conductive paint on a substrate.
It is used in an amount so that the viscosity is as high as possible. Furthermore, when a water-soluble Bingu resin is used, water can be used as a solvent.

When preparing a conductive paint, in addition to the above (a) conductive oxide powder and (b) binder resin, conductive 4 fine (
3) In order to improve the dispersibility of the powder and prevent particles from re-agglomerating, a surfactant can be added, and a wide range of surfactants such as anionic, nonionic, and cationic surfactants can be used. Can be done. Furthermore, a coupling agent can be added to the conductive paint in order to improve the dispersibility of the conductive fine powder and prevent the particles from re-agglomerating. As such a coupling agent, a silane-based, titanium-based, aluminum-based, zirconium-based, or magnesium-based coupling agent is used.

In the method for producing a conductive paint according to the present invention, (a) a conductive powder (b) a binder (adding a resin etc. to a solvent and then a binder) or Although uniformly dispersed, the (a) conductive fine powder may be pulverized at the same time as described above in the kneading of (a) the conductive fine powder and (b) the binder resin [14].

The conductive paint produced in accordance with the present invention is coated on a substrate using conventional methods such as bar code method, spray method, roll coating method, spinner method, dip method, tire bar method, and air knife method. A coating film 11 is applied by methods such as gravure printing, screen printing, etc., and then dried to form a conductive coating film of 1q.

Effects of the Invention According to the method for producing conductive raw paint according to the present invention, conductive fine particles having an average particle size of 0.4μ7n or less and a sharp particle size distribution in the paint can be obtained; The conductive paint containing Hλ has excellent conductivity, has a smooth surface, and has a rough surface of 0.8 μm or more. It is also excellent.

The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 316.0 g of tin-shun potassium and 38.47 g of tartarite were
A raw J'il solution was prepared by dissolving it in water 6867.

Add the above raw material solution together with nitric acid over 12 hours to 1 oooy of water heated to 50 ° C and stirred,
1) in the system and hydrolyzed in H8,5, sol) 1
I got the evening. Colloidal particles are filtered from this sol solution, washed to remove by-product salts, and then dried,
The mixture was calcined at 650 C for 3 hours and then in air at 650 C for 2 hours to obtain a fine powder (if! To the end). (Add and mix the q powder Δ1507 and Boudral resin 647 in i-propatool/n-butanol (=ilift ratio)/1> ratio/1 agent 50 (l), and grind this with a sand mill for 2 hours. A conductive image O'31 was obtained.

This coating: R31 was applied to a thickness of 100 using bar coater #6.
A coating film was obtained by applying it to a μ PFT film and drying it at 110°C for 30 minutes.Example 2 Example 1 I'! /') powder A150y and melamine resin 26.5y are mixed with methyl ethyl ketone/;~luene (
The mixture was mixed with 200 y of a kneading solvent (with an ω ratio of 1/1) and ground in a Nando mill for 1 hour to obtain IJ'E+.

Temporarily apply this paint to the glass using bar coater #6.
Let it dry for 150'010 minutes and then dry the paint film.

Example 3 Powder △150tj obtained in Example 1 and PVC/Vinyl Acetate Copolymer Resin 1509 were mixed in 500g of a mixed solvent of methane/toluene (drying ratio 1/1). 3 hours in a lint mill? ,'j,! It's time to put the paint on it.

Apply this paint to a 100μ PET film using a spinner (2000r, p, m, ) at 110°C.
A coating film was obtained by drying for 10 minutes.

Comparative Example 1 A solution was prepared by dissolving 173 g of tin chloride and 20.9≦1 antimony chloride in 300 cck of methanol. 90
The above solution was added over 4 hours to 30,000 °C of water under stirring to carry out hydrolysis.The formed precipitate was separated and washed, and after drying, °
A coating film was prepared under the same conditions as in Example 1 except that a fine powder was obtained by baking at C for 2 hours.

Example 4! A solution of i1'l Rin indium 79.97 dissolved in water 6867 and potassium stannate 12.7S7 at 10,000%
A solution was prepared in potassium water solution. 50'
The above-mentioned indium nitrate solution and potassium stannate solution were added over 2 hours to 1 oooy of water heated to a temperature of Decomposition was performed to obtain a sol solution.

After removing colloidal particles from this sol solution and washing 1 to remove by-product salts, the particles were dried, calcined in air at 350'C for 3 hours, and roughly heated in air at 600'C for 2 hours. Calcinate to obtain a fine powder (■da ((shi) powder B). Obtained!: Powder B15 (L) and UV curing resin 647 are mixed with isophorone 500
9 and pulverize it with three rolls to make a paint. This paint was screen-printed onto glass and cured with ultraviolet light to obtain a paint film.

The average particle diameter of the conductive fine particles contained in the paints obtained in the above Examples and Comparative Examples and 0.8μIr1. More coarse 1! Using a centrifugal particle size measuring device (Horiage Manufacturing Co., Ltd.), the content of Q-koi was adjusted to 5000r, I), and the solid content of the measurement sample liquid was adjusted to 0.5% by weight.

It was measured with Also, the total light transmittance of the obtained coating film (1)
, /\-'s (['') is a Heath computer (manufactured by Suga Test Instruments), and the surface resistance (Rs) is an electric current (both cells (YH
(manufactured by P. Co., Ltd.).

The results are shown in Table-1.

From Table 1, it can be seen that according to the packaging method of the conductive paint according to the present invention, the content of coarse particles with a particle size of 0.8 μm or more is small, and the conductivity, I know it's paint or 17.

Agent Patent Attorney Shunichi Suzuki Wa°to Neyama Choichimi 7U November 11, 1986 [1 1!已' [Agency Commissioner Black 1) Akira 7j Tono Riden (Manufacturing method 7 of I coating 1, contents of amendment 1) Specification 11, page 5, 1611 [13] Containing the conductive first eye maI, it says,
``The coating film produced from the conductive paint containing these conductive fine particles is corrected to be 1.1.

2) Specification: In page 5, line 17 of J-1, the phrase "has a smoothness of 11.41 points" has been amended to "has excellent smoothness."

3) il'j on page 10, line 2 for details, ro, 05
~0.3μ"ro, 05~0.3μyrtJ
1゜4) Bright; till ; t'f il) on page 10, line 3, and ro: 07~0.2μ'' should be changed to ``0.07~0.
．． 2 μIrL”.

5) In the specification μm, page 12, lines 1 to 8, it is stated that ``Specifically, for example, Jn-based vinyl resin...I1 etc.'' is replaced with ``Specifically, for example, melamine Acrylic resins such as polyethylene resins, urea resins, amine resins such as melamine resins, polyamide resins, polyimide resins, polyamide-imide resins, polyurethane resins, polyether resins, alkyl resins, etc. Polyester resins, epoxy resins, chlorinated polyether resins, polyethylene resins, polyolefin resins such as Bolibu L1 pyrene resins, polyether-1 resins, silicone resins, borisdylene resins, etc. Resin, ΔI3S resin, polyamine sulfone A resin, borini [-delsulf A 4aJ resin, polysulfone resin such as polyphenylene sulfton resin, vinyl chloride resin, vinylidene chloride resin, vinyl n-acid (li
(Vinyl resins such as resins, polyvinyl alcohol resins, polyvinyl carbazole resins, and butyral resins, fluorine resins, polyphenyl resins, oxide resins, polypyrrole resins, borine 7/raphenylene resins, ultraviolet curing resins, and cellulose derivatives, etc.) "Used."

C) In J3 on page 13, lines 2 to 5 for specification filing, the statement ``Specifically, for example, methyl edyl ketone, . Specifically, methanol, ethanol, lowobanol, i-
Alcohols such as propatool, n-butanol, i-butanol, cyahedone alcohol, and cyclohekylinol; Mejiru Zero Solve, Edil Zero Sorte,
Ethers such as carbitol, mebul carbitol, bubul carbitol, gin:1niline, f'1M
Esters such as IQ ethyl, stones such as henylene, cyclohexyl, etc., pensoles such as toluene, xylene, and turbento, N-methyl-2-pyrrolidone d3 J: Bizo derivatives, etc. Can be used alone or in combination. 1” is corrected.

7) On page 15, line 29 of the specification, the phrase "this conductive paint containing conductive fine particles is" has been replaced with "the coating film formed from this conductive paint containing conductive fine particles is". Correction Jru.

8) In the second line of page 15 of the specification, the phrase "excellent in transparency" should be changed to "excellent in transparency." Furthermore, this coating film has the effect of blocking infrared rays and ultraviolet rays. ” he corrected.

9) Page 15, line 2 of the specification (in lines 13 and 17, "100μ" is corrected to k r "I 00μIrtJ.

10) J3 in Table 1, 1900 for specifications, [average particle size]
The expression ``average particle size (μ)'' has been corrected to ``(μmrL)''.

Claims (1)

[Claims] (1) (a) A sol containing colloidal particles is produced by maintaining an aqueous solution of a tin compound or an indium compound under a pH condition of 8 to 12 and gradually hydrolyzing the compound in the solution, and then A method for producing a conductive paint, which comprises dissolving or dispersing a conductive fine powder obtained by drying, firing, and pulverizing this sol, and (b) a binder resin in a solvent.