JPS5831234B2 - Tomaku no Keiseihouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for uniformly forming a coating film made of powder and a binder over a wide area, and in particular, the present invention relates to a method for uniformly forming a coating film made of powder and a binder over a wide area. This method is effective when forming large, relatively thick coatings.

In general, when forming a coating film, it is applied by a brush coating method, spray method, squeegee method, screen method, sedimentation method, dipping method, etc., and then heated with a dryer, infrared lamp, panel heater, etc., or left to stand naturally. Various methods that suitably combine drying and curing methods have been put into practical use.

The main factors determining the quality of these coating films were the uniformity of their thickness and the homogeneity of the dispersion of the powder material.

However, in the case of coatings formed by mixing electrical material powder with a binder, the microscopic homogeneity greatly affects the properties of electrical devices that use them, especially in the drying and curing process of the coating. The uniformity of drying speed and other factors is important.

This tendency is remarkable when a thick coating film is formed using a powder material having a relatively large particle size, such as an electroluminescent material or a photoconductor.

It has become clear that in the production of image display devices using these materials, the drying speed and local non-uniformity of the drying state, that is, drying unevenness, greatly influences image characteristics.

From this point of view, the present invention provides a method for easily forming a relatively thick coating film made of electrical material powder and a binder in a microscopically homogeneous manner.

The first point is that after a mixture consisting of a powder material, a binder such as a resin, and its solvent is applied onto a substrate, during the drying process, the surface of the applied layer comes into contact with the vapor atmosphere of the solvent contained inside. In this state, the solvent gradually evaporates and dries.

As a result, when the conventional coating film is thick, it dries from the surface and the inside dries out. In extreme cases, a binder resin film forms on the surface while the inside is still wet. , defects such as the solvent remaining inside, or the solvent breaking through the surface layer during heat curing and causing the surface to become pockmarked, are removed, and the coating dries to the inside with a uniform coating. It is something.

The second step is to form the solvent atmosphere layer under conditions necessary for homogeneous drying.

This depends on many factors, such as the area of the coating film, the film thickness, the mixing ratio of the powder material and the bonding uniformity 0, the type of binder and solvent used, especially their curing temperature, boiling point, the amount used, and the ambient temperature. different.

Therefore, in relation to these factors, the thickness and height of the solvent atmosphere layer and the speed at which it is gradually removed may be appropriately selected and adjusted.

The third is a specific method that makes such adjustment extremely easy.

That is, in order to define the required thickness, a lid-like object such as a plate is provided at a height corresponding to the required thickness.

Next, in order to adjust the degree of discharge, a large number of through holes are provided on the entire surface of this lid-like object.

For example, a net-like lid may be provided.

Furthermore, in order to adjust the speed, it is effective to also provide a temperature raising mechanism by heating.

In this case, it is necessary to heat gradually and uniformly over the entire surface without causing turbulence, and an effective method is to form the lid-like object with a heating plate and provide the necessary number of through holes in it. It is.

That is, it is practical to use a panel heater made of a plate-shaped material containing a heater, a conductive glass, or the like, provided with the necessary number of through holes, and uniform temperature control can be easily achieved by adjusting the amount of current applied.

In particular, the use of conductive glass having a transparent electrode allows the dry state of the coating film to be observed from above, which is convenient for various adjustment operations.

Here, in relation to various factors, the size, shape, number, and distribution of the through holes provided in the heating plate, as well as their operating temperature and installation position (height from the coating surface) must be determined appropriately. Bye.

Furthermore, if necessary, a low speed fan can be installed above the heating plate to adjust the discharge speed.

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

Example 1 As shown in Fig. 1, the length is 20crrL1 the width is 16crrL
On a conductive glass substrate 2 having a transparent electrode 1 with a thickness of 371 m, 10 g of ZnS electroluminescent powder, 10 g of a urea resin binder (Uvan 10 S, Mitsui Koatsu), and 1.5 g of diacetone alcohol were kneaded. The coating liquid was applied by a silk screen method, and the formed coating film 3 was immediately left at the bottom of the box 4 in an undried state.

Next, a large number of holes 5 with a diameter of 3 to 5 m are provided at intervals of about 5 m on a conductive glass plate with a thickness of 3 pairs on which transparent electrodes made of 5N02 or In2O3 (resistance value of 100 Ω - about 100 ohms) are formed on the surface. A lid-like heating plate 7 provided with voltage applying electrodes 6°6' was placed at a height H)20 (m) from the bottom.

A power source 9 is connected between the electrodes 6 and 6' at both ends via a voltage regulator 8.
connected.

For example, if the temperature of the internal solvent vapor atmosphere layer 10 is adjusted to 30 to 35°C by applying about 50μ,
It takes about 120 minutes for the entire surface to become uniformly dry.

This was taken out and cured in a hot air circulation dryer at 180° C. for 30 minutes to obtain a homogeneous coating film of about 55 μm.

The electroluminescent panel was operated by providing an AI vapor-deposited electrode thereon and applying a voltage of 150 V between it and the transparent electrode 1. The homogeneity of the light emitting characteristics was extremely good.

Example 2 Without forming the A1 electrode on the electroluminescent layer coating 3 formed in Example 1, a reflective layer made of BaTiO3 (approximately 10 μm) and an opaque layer made of carbon (approximately 10 μm) were added.
Cd Se-based photoconductor powder 4 (Bi'), 3 g of a cellulose-based resin binder (ETCEL, manufactured by Nissin Kasei), and a mixture of toluene and butyl acetate 3e as a solvent were mixed on the substrate formed by sequentially stacking the following. 300~
It was formed to a thickness of about 350 μm, and immediately placed in the same box 4 as in Example 1 in an undried state.

Next, the height H) of the same perforated conductive glass heating plate 7 is 2.
5 at the carp, and set the temperature of the solvent vapor atmosphere layer 10 to 3.
By heating the temperature to about 0 to 50°C and rotating a small, low-speed suction/exhaust fan installed at a position 20 (m) above the heating plate 7, a coating film of about 300 μm can be removed over the entire surface in about 180 minutes. Dried evenly.

This was taken out and placed in a hot air circulation dryer at 120°C.

A photoconductor layer was formed by curing for 60 minutes.

The X-ray imaging device panel obtained by forming an AI vapor-deposited electrode thereon is particularly suitable for other drying methods in forming the photoconductor layer.
For example, an X-ray converted image with excellent image quality and uniformity that could not be obtained by infrared heating, vacuum heating, hot air drying, etc. was obtained.

In addition, defects caused by uneven drying in this drying process were almost eliminated, and the effect on yield improvement was also significant.

As explained in detail above, the present invention allows a base body having a wet coating film to be placed at the bottom of a box, and a heating plate having a large number of through holes placed on top of the base body at a necessary distance. The coating film surface is always in contact with an atmosphere at a certain temperature of the solvent vapor contained therein, and the vapor atmosphere layer is gradually discharged to reproduce a large, relatively thick coating film uniformly and without uneven drying. This is an effective method to form a good shape.

In particular, the effect is even more remarkable when forming coatings in structures such as video display devices, where slight unevenness in drying subtly affects the image quality, and its industrial value is extremely significant. be.

[Brief explanation of drawings]

The figures are for a detailed explanation of the invention. 2...Substrate, 3...Coating film, through hole, 6
, 6'...electrode, 4...box, 5...7...heating plate with through holes, 9...power supply , 10...Solvent vapor atmosphere layer.

Claims (1)

[Claims] 1. A substrate coated with a mixture of powder, binder, and solvent is placed on the bottom of the box, and a heating plate with a large number of through holes is placed on the top surface at regular intervals to dry and harden. A method for forming a coating film characterized by the following.