JPS59102932A - Coating of electrically-conductive transparent paint - Google Patents

Abstract

PURPOSE:To obtain a coated film having improved electrical conductivity and transparency with preventing agglomeration and caking of fine powder of metal, by dehydrating an electrically-conductive transparent paint consisting of specific fine powder of metal oxide, a binder, and a solvent with a dehydrating agent, followed by applying it to the surface of a molded article. CONSTITUTION:An electrically-conductive transparent paint comprising fine powder of metal oxide(preferably <=0.4mum average particle diameter) consisting essentially of copper oxide containing 0.1-20wt% anitomony, a binder(e.g., polyvinyl chloride, etc.) and a solvent(a solvent dissolving the binder such as methyl ethyle ketone, etc.) is dehydrated with a dehydrating agent(e.g., silica gel, etc.) before it is agglomerated or caked), and it is applied to a molded article of synthetic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of applying a conductive transparent paint containing fine metal oxide powder to the surface of a synthetic resin molded article while maintaining stable quality of the paint.

A fine metal oxide powder is solidified on the surface of a synthetic resin molding, and the surface is given electrical properties.As a method, a paint containing a fine metal oxide powder dispersed in a binder and a solvent is used.
There is a method of applying it evenly to the surface of the finished product.

In recent years, coating films applied to synthetic resin molded articles such as packaging materials for electronic parts are often required to have both electrical conductivity and transparency.

Therefore, the particle size of the metal oxide fine powder contained in the conductive paint is as fine as possible (average particle size of 0 g μm or more).
By doing so, transparency is improved.

However, even with paints using such fine metal oxide powders, a coagulation phenomenon occurs during application and storage ((a coagulation phenomenon in which the metal fine powders contained in the paint separate from other components, coagulate, and settle). can be seen.When this coagulated paint is applied,
An increase in the surface resistivity of the coating film, opacity of the coating film, and poor appearance are likely to occur.

As a result of intensive studies to prevent the above-mentioned troubles, the inventors of the present invention found that the main cause of the above-mentioned coagulation phenomenon is the moisture contained in the paint and the moisture absorbed from the surrounding air. It has been found that such minute amounts of moisture are absorbed into the surface of the metal oxide fine powder, increasing the affinity between the particles, and as a result, the metal fine powder coagulates and coagulates.

The present invention has been made based on this knowledge, and after contacting a conductive transparent paint containing a metal oxide fine powder made of tin oxide, a binder, and a bath agent as components with a dehydrating agent Q and dehydrating it. , a method of applying a conductive transparent paint, the main feature of which is applying it to the surface of a synthetic resin molded article.

The metal oxide fine powder used in the present invention contains antimony in O
/~20% by weight, the remainder being substantially tin oxide, and the average particle size is 0/1. It is preferable that the thickness be less than .mu.m because it can improve effects such as conductivity. Here, to explain the average particle size of the lung, a polyethylene cylindrical container (inner diameter 'i', 5 nunφ,
6g of fine metal powder and 1Occ of water in a container (10occ)
(2) Sintered alumina ball 5 with a diameter of about 10 rmnφ
After rotating this container at a rotation speed of 90 Or, p, m for 10 hours, the contents except for the sintered alumina balls were placed in a centrifugal sedimentation II container. The powder is allowed to settle while changing the rotation speed and rotation time, and the weight of each settled powder is measured. Based on the measurement results, a particle size distribution is created, and the
The cumulative value of 0% was taken as the average particle size.

Furthermore, the binder may be one that is used in ordinary conductive paints, such as polysaltyl vinyl, polyester, polystyrene, polyvinyl alcohol, and mixtures thereof.

Furthermore, the solvents are those that dissolve the binders mentioned above, such as methyl ethyl ketone, nclohexane, ethyl acetate,
Tetrahydrofuran, cellosolve acetate, toluene, mixtures thereof, and the like can be used. In addition, surfactant,
Thickeners may also be added.

Next, as for the dehydrating agent used in the present invention, ordinary dehydrating agents can be used. Dehydrating agent + (C+s) is divided into adsorption type and absorption type depending on the dehydration mechanism, but the adsorption type is advantageous in terms of cost because it can be used repeatedly.In other words, with adsorption type dehydrating agent, water is absorbed into the dehydrating agent. Moisture in the paint is removed by being adsorbed into its own fine pores, but this adsorbed water can be easily removed from the dehydrating agent by heating or reducing the pressure, so do not perform this operation. The above-mentioned adsorption type dehydrating agents include synthetic or natural zeolite, aluminum oxide, silica gel, etc. Absorption type dehydrating agents chemically absorb moisture. It forms a hydrate, and examples include calcium chloride and phosphorus pentoxide.

In the present invention, the conductive paint is brought into contact with the dehydrating agent,
After dehydration, it is necessary to apply the paint to the surface of the synthetic resin molding. Dehydration method 1 Shishi is the method of holding the dehydrating agent in the paint container, the method of holding the dehydrating agent in the paint storage tank or application pan during the coating process, and the method of filling the dehydrating agent. A dehydration tower is installed during the coating process, and coating
There are methods such as passing the paint through a dehydration tower before coating, and circulating the remaining liquid after coating and passing it through the dehydration tower. The above method may be used in combination to improve the effect. Here, it is necessary to apply dehydration before the metal oxide fine powder in the paint coagulates, settles, and coagulates. However, no effect is observed after coagulation occurs.

Although the method of the present invention reduces the amount of water in the paint and prevents the coagulation phenomenon, there is a limit to the amount of water that can prevent this coagulation phenomenon, depending on the type and combination of binders and solvents contained in the paint. The dehydrating effect can be adjusted as appropriate by changing the contact time between the dehydrating agent and the paint or by changing the company using the dehydrating agent.

The coating method used in the present invention varies depending on the molded product, but examples include gravure coating, reverse coating, tire-bar coating, air knife coating, spraying, and brushing. Also, synthetic resin molded products icf';! , polyvinyl chloride resin, polyester MJ
JJ? Examples include films, sorts, plates, and other various molded products made of synthetic resins such as J.

Next, the present invention will be explained in detail with reference to examples.

Example A solid content containing 70% by weight of antimony, the remainder substantially consisting of tin oxide, A5 weight ratio of metal oxide fine powder with an average particle size of 02 μm, and 35% by weight of a polyester binder. Add the above-mentioned solids to each solvent having the composition shown in Table-/ so that the content becomes 25% by weight of the whole, and then add water to adjust the water content shown in Table-/ to conductivity 1. Got the paint. After stirring each of these paints for 7 minutes,
It was placed in a transparent airtight container with a dehydrating agent (zeolite) and allowed to stand still. The additional amount of dehydrating agent was set to 70% of the paint weight. As a comparative example, the same operation was performed without using a dehydrating agent. After each paint was allowed to stand, the presence or absence of coagulation of fine metal powder was visually observed. The results are shown in Table 7. The moisture content was measured using a digital microwrinkle moisture 6 (CA-0/, manufactured by Mitsubishi Chemical Industries, Ltd.) K.

Table 7 shows that although there are differences depending on the solvent composition, the use of a dehydrating agent has a significant coagulation prevention effect. Next, when the paint according to the present invention was applied to a transparent polyester film with a thickness of 2 Sμ at a coating thickness of 1μ using the barcode method, it was possible to apply it uniformly, and the obtained film had good conductivity and transparency. Ta.

However, in cases where coagulation occurred, it was difficult to apply uniformly and was not practical.

As described above, according to the method of the present invention, a conductive transparent paint with stable qualities such as conductivity and transparency can be obtained, and each;
Dogs are useful for manufacturing tmE baby materials, parts, etc.

Applicant: Mitsubishi Plastics Co., Ltd.

Claims (1)

[Claims] Contains 07-20% by weight of antimony, with the remainder being substantially (
(Metal oxide fine powder made of tin oxide, a binder,
A method for applying a conductive transparent paint, which is characterized in that the conductive transparent paint containing a solvent as a main component is applied to the surface of a synthetic resin molded article, which has been dehydrated by contacting the conductive transparent paint with a dehydrating agent.