JPS6227474A - Production of electrically conductive coating fluid - Google Patents

Abstract

PURPOSE:To produce the title coating soln. which causes neither agglomeration nor precipitation of an ultrafine powder of tin oxide and which can maintain a uniform composition over a long period of time, by mixing a predried ultrafine powder of tin oxide and a binder resin with a dehydrated solvent. CONSTITUTION:A tin oxide dispersion obtd. by dispersing an ultrafine particle of tin oxide immediately after predrying in a dispersant soln. immediately after dehydration is mixed with a binder resin soln. obtd. by dissolving a binder resin immediately after predrying in a solvent immediately after dehydration.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing an electrically conductive coating liquid by dispersing ultrafine tin oxide particles in a solvent containing a binder resin.

[Conventional technology]

The above-mentioned type of conductive coating liquid is suitable for use as a coating agent for reducing the surface electrical resistance of plastic materials and preventing dust adsorption.

Conventionally, such conductive coating liquids are made by using ultrafine particles of tin oxide doped with antimony trioxide, which have a zero resistance to tin oxide.
．． A tin oxide dispersion was prepared by mixing 5 to 5 tmt% of a dispersant into a solution, and the tin oxide dispersion was mixed with a binder resin solution.

In such conventional methods, aromatic solvents such as xylene and toluene, or solvents belonging to ketones such as methyl isobutyl ketone and methyl ethyl ketone are used as the solvent for the dispersant, and a surfactant (for example, -Product name 5AS-13 manufactured by Industrial Pharmaceutical Department, Product name 93 manufactured by Ajinomoto ■
etc.) are used, and as the tin oxide ultrafine particles, for example, Mitsubishi Metals' product name T-1 or the like is used. On the other hand, the binder resin used is, for example, vinyl chloride resin, acrylic resin, polyester resin, etc., and the binder resin solvent is cyclohexanone or methyl isobutyl ketone.

Solvents, solvents, aromatic solvents, etc. are used. Further, a stirring device such as a homogenizer, a ball mill, or a sand mill is used to mix the ultrafine tin oxide particles and the dispersant solution, and to mix the tin oxide dispersion and the binder resin solution.

[Problem that the invention seeks to solve]

However, if a conductive coating solution produced by the above conventional method is left to stand after production, the ultrafine tin oxide particles often separate from other components and aggregate or precipitate within several days.

As a result of repeated investigations on this point, the inventor of the present application has found that the agglomeration and precipitation of ultrafine tin oxide particles is due to a small amount of water being adsorbed and supported on the surface of ultrafine tin oxide particles before being mixed into the dispersant solution.2. We found out that water is contained in the solvent of the binder resin and the solvent of the binder resin, and furthermore, we found that water is adsorbed and supported on ultrafine tin oxide particles and that water is contained in the solvent. I found out that the previous one was being saved.

The present invention was made as a result of such research, and the tin oxide ultrafine particles dispersed in the conductive coating solution do not aggregate or precipitate even if left for a long period of time after manufacture, and can be maintained for a long period of time. The purpose of the present invention is to propose a method for producing a conductive coating liquid that maintains a uniform composition throughout.

[Means for solving problems]

In order to solve the above problems, the present invention provides a method for producing a conductive coating liquid in which a tin oxide dispersion prepared by mixing ultrafine tin oxide particles into a dispersant solution is mixed with a binder resin solution. Pre-drying the ultrafine particles immediately before mixing them into the dispersant solution, dehydrating the dispersant solvent and binder resin solvent immediately before dissolving the dispersant and binder resin, and further dissolving the binder resin in the solvent. The main point is to pre-dry it.

[For production]

According to the above means, water adsorbed and carried on the surface of ultrafine tin oxide particles mixed into the dispersant solution is removed prior to mixing into the solution. In addition, water contained in the solvent of the dispersant and the solvent of the binder resin is removed prior to dissolving the dispersant and the binder resin in these solvents. Furthermore, the binder resin is pre-dried immediately before being dissolved in the solvent.

The method of the present invention will be explained below with reference to experimental examples.

[Experiment example]

A tin oxide dispersion and a binder resin solution were prepared separately by the method described below.

(Preparation of al tin oxide dispersion) Xylene 41 immediately after adding an appropriate amount of silica gel and dehydrating
2.06g of Ajinomoto brand 9s as a dispersant was dissolved in 2.5 cc, and tin oxide ultrafine particles (pre-dried by standing in a dryer at 105.5°C for 3 hours) were added to this dispersant solution. 206° (4 g) of T-1 (trade name, manufactured by Mitsubishi Metals Ltd.) was mixed in and dispersed in a ball mill with a diameter of 15 CI11 for about 2 days.

(b) Preparation of binder resin solution Add a suitable amount of silica gel to 412.5 cc of cyclohexanone immediately after dehydration, and dry at 50 to 60°C. Polyvinyl chloride resin (trade name: Lyuron 800BL) 41.
3 g was dissolved, and 1.24 g of Nitto Kasei ■ trade name 112000E was mixed therein as a stabilizer.

Next, a binder resin solution was mixed into the tin oxide dispersion prepared by the above method, and a conductive coating liquid was prepared by performing a dispersion treatment for 3 days using the above ball mill.

On the other hand, as a comparative example, the above-described pre-drying of ultrafine tin oxide particles, xylene, and cyclohexanone were used.

A conductive coating liquid was prepared under the same conditions as above except that the polyvinyl chloride resin was not dehydrated.

[Consideration of experimental results]

The conductive coating liquid according to the method of the present invention prepared in the above experimental example showed almost no aggregation or precipitation of ultrafine tin oxide particles even after long-term storage for about 3 months. Furthermore, the surface condition of the plastic plate after the conductive coating liquid was applied to the plastic plate after storage for the above-mentioned period was good.

On the other hand, in the conductive coating liquid according to the comparative example, ultrafine tin oxide particles began to precipitate during storage for several days after preparation.

In the method of the present invention, as the solvent for the dispersant, in addition to the above-mentioned xylene, aromatic solvents such as toluene and solvents belonging to ketones such as methyl isobutyl ketone and methyl ethyl ketone can be used, and as the binder resin, the above-mentioned polyvinyl chloride can be used. In addition to resins, acrylic resins and polyester resins can be used, and as solvents for the binder resin, in addition to the above-mentioned cyclohexanone, methyl isobutyl ketone, cellosolve, aromatic solvents, etc. can be used, and as dehydrating agents, the above-mentioned solvents can be used. In addition to silica gel, zeolite etc. can also be used.

〔Effect of the invention〕

According to the present invention, it is possible to produce a conductive coating liquid with stable quality, which does not cause agglomeration or precipitation of ultrafine tin oxide particles even if left for a long period of time.

By the way, in the method of the present invention, by pre-drying the tin oxide fine particles immediately before mixing them into the dispersant solution, it is possible to prevent the water adsorbed and supported on the surface of the particles from being mixed into the dispersant solution, and also to prevent the water adsorbed on the surface of the tin oxide particles from being mixed into the dispersant solution. By dehydrating the dispersant and binder resin immediately before dissolving them in each solvent of the resin, and pre-drying the binder resin before dissolving it in the solvent, it is possible to prevent water from entering the dispersant solution or binder resin solution. This is to prevent

Regarding such a method of the present invention, it is also conceivable to remove moisture from the conductive coating liquid by adding a dehydrating agent such as silica gel or zeolite into the conductive coating liquid after manufacturing the conductive coating liquid. However, with this method, it is difficult to sufficiently remove the moisture adsorbed and supported on the ultrafine tin oxide particles before they are mixed into the dispersant solution, and compared to the method of the present invention in which the moisture is removed by pre-drying. There is a marked difference in the effects. Furthermore, when a dehydrating agent is added to a conductive coating liquid, the binder resin dissolved in the coating liquid adheres to the dehydrating agent, making it difficult to separate the dehydrating agent, and even if it is separated, the dehydrating agent is Since the surface is covered with a resin film made of binder resin, it is difficult to regenerate it. The same can be said of the case where water is removed by adding a dehydrating agent to the binder resin solution. Therefore, the method of the present invention, which does not cause such inconvenience, enables the dehydrating agent to be recycled and reused, and can be said to be a highly economical method.

Note that the method of the present invention only mentions pre-drying the ultrafine tin oxide particles, dehydrating the dispersant and binder resin solvents before use, and pre-drying the binder resin. This is not to exclude dehydration of the dispersant before use. That is, the dispersant solution can be easily dehydrated by adding a dehydrating agent such as silica gel, and the dehydrating agent can be easily recycled and reused.
The dispersant may be dehydrated before use, and it is preferable to perform this operation in order to suppress agglomeration and precipitation of ultrafine tin oxide particles in the conductive coating liquid.

Claims (1)

[Claims] (1) In a method for producing a conductive coating liquid in which a tin oxide dispersion prepared by mixing ultrafine tin oxide particles into a dispersant solution is mixed with a binder resin solution, ultrafine tin oxide particles are mixed into the dispersant solution. In addition to pre-drying immediately before
A method for producing a conductive coating liquid, which comprises dehydrating a dispersant solvent and a binder resin solvent immediately before dissolving the dispersant and binder resin, and pre-drying the binder resin immediately before dissolving the binder resin in the solvent.