JPS6223420B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of forming a graphic powder coating layer on a transparent substrate. In particular, the present invention relates to an improvement in the method of forming a patterned powder coating layer suitable for producing a fluorescent surface of a color cathode ray tube.

The production of a color cathode ray tube fluorescent surface will be described below as an example.

The inner surface of the screen portion (face plate) of a color cathode ray tube is coated with three types of phosphors that emit red, green, and blue light in the form of dots or stripes. A conventional method for forming this phosphor coating layer is as follows. First, a layer of a mixture of a first color phosphor and a photosensitive resin is formed on the inner surface of the face plate. A mixture of polyvinyl alcohol and ammonium dichromate is commonly used as a photosensitive resin. This layer is usually formed by applying a mixture of a photopolymer solution and a phosphor to the inner surface of the faceplate and drying. This layer is then irradiated with ultraviolet light through the holes in the shadow mask. The ultraviolet irradiation position at this time corresponds to the position where the electron beam for causing the phosphor to emit light strikes, that is, the position where the phosphor is to be fixed. The photosensitive resin in the area exposed to the ultraviolet rays becomes insolubilized, thereby making the entire layer in that area insolubilized. The layer is then washed with a solvent (usually water), leaving only the portions that have been insolubilized by UV irradiation remaining on the face plate surface, and the remaining layers are dissolved and removed. Next, similar processing is performed for the second color phosphor and the third color phosphor.

As described above, the manufacturing process for the fluorescent surface of color cathode ray tubes is complex and requires multiple wet coatings and
This simplification is highly desirable since repeated washing and drying steps are required.

For this reason, some of the inventors previously proposed a method for forming a fluorescent surface of a color cathode ray tube using a significantly simpler process than the conventional method in Japanese Patent Application No. 52-41465 (Japanese Patent Publication No. 57-20651). Proposed. This method was completed based on the new knowledge that photodecomposition products of aromatic diazonium salts have the ability to accept powder particles, and is a method for forming a patterned powder coating layer on the surface of a substrate. (1) The first step of applying an aromatic diazonium salt or a photosensitive composition containing an aromatic diazonium salt as a photosensitive component that becomes sticky upon exposure to the substrate surface to form a thin layer; (2) applying the thin layer to the surface of the substrate; a second step in which the exposed area is made sticky by exposing the exposed area to light; and (3) powder particles are brought into contact with the thin layer after exposure, and the powder particles are The method is characterized in that it includes a third step of making the thin layer receive the.

However, the sensitivity of the diazonium salt used in such a method is not necessarily higher than that of a mixture of polyvinyl alcohol and ammonium dichromate, which is a conventional photosensitive resin.

The present invention aims to improve this problem and shorten the exposure time through a shadow mask.

The present invention utilizes the fact that the aromatic diazonium salt used as the photosensitive component is generally colored and has high photodecomposition efficiency, so it decomposes one after another starting from the surface that is exposed to light. It is characterized in that back exposure is performed from the transparent substrate side on which the powder coating layer is formed, that is, from the face plate side in the case of manufacturing color cathode ray tubes.

That is, as shown in FIG. 1a, the photosensitive composition 1 containing the diazonium salt is exposed in advance to ultraviolet light from the face plate 4 side, and the diazonium salt is applied to the surface of the diazonium salt to the extent that the film surface 2 of the diazonium salt does not become sticky. decompose. Next, as shown in FIG. 1b, exposure is carried out through a shadow mask 5 to impart adhesiveness to the position where the phosphor is to be attached. This method allows the exposure time through the shadow mask to be shortened. In the figure, 3
indicates the decomposed part of the diazonium salt.

As mentioned above, by performing one back exposure in advance, all three exposures can be shortened to deposit three colored phosphor layers, thereby reducing the total exposure dose. .

The aromatic diazonium salt used in the present invention is
These include those described in the specification of Japanese Patent Application No. 52-41465.

That is, aromatic diazonium chloride/zinc chloride double salt, such as 4-dimethylaminobenzenediazonium chloride-(1)/zinc chloride double salt, 4-diethylaminobenzenediazonium chloride-(1)/zinc chloride double salt, chloride 4- Aromatic diazonium tetrafluoroborates such as (N-ethyl-N-hydroxyethylamino)benzenediazonium-(1) and zinc chloride double salt, such as 4-dimethylaminobenzenediazonium-(1)
Hydrobofluoride, 4-methoxybenzenediazonium-(1) hydroborofluoride, 2-methoxybenzenediazonium-(1) hydroborofluoride, etc., or aromatic diazonium acid sulfates, such as 4-dimethyl sulfate Aminobenzenediazonium-(1), 4-diethylaminobenzenediazonium-(1), and the like are used. Of course, two or more types may be mixed and used.

It has already been disclosed in Japanese Patent Application No. 1972-1 that it is preferable to mix an organic polymer compound and/or a surfactant for the purpose of improving the coating properties of the photosensitive composition.
41465 specification.

It is preferable that such a composition is also used in the present invention.

Organic polymer compounds include hydroxypropyl methylcellulose, gum arabic, polyvinyl alcohol, polyacrylamide, poly(N-vinylpyrrolidone), acrylamide/diacetone acrylamide copolymer, alginic acid, propylene glycol ester of alginic acid, methyl vinyl ether/maleic anhydride. One or more types of acid copolymers are used. The amount of these organic polymer compounds is 0.5 to 500% relative to the diazonium salt.
Parts by weight are preferred, and 1 to 50 parts by weight are more preferred.

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 4 parts by weight of 4-dimethylaminobenzenediazonium chloride (1) zinc chloride double salt, alginate propylene glycol ester (trade name Chimiloid)
A photosensitive composition consisting of 0.8 parts by weight (manufactured by Kimitsu Kagaku Kogyo KK) and 95.2 parts by weight of water was coated onto a glass plate by spin coating and dried to form a photosensitive thin layer with a thickness of about 0.5 μm.

For this, an ultra-high pressure mercury lamp is used to illuminate the plate glass side.
After exposure for 40 seconds at 10,000 lx, exposure was performed for 40 seconds at the same illuminance from the shadow mask side. A green-emitting phosphor was then applied to the surface of this photosensitive thin layer by dusting in air at a relative humidity of 40%. That is, the phosphor powder was sprinkled on the surface of the thin layer, and after the phosphor powder adhered to the exposed portions of the thin layer, the remaining phosphor particles were removed by air spray.

Next, the blue-emitting phosphor was applied by dusting after irradiating the light from the ultra-high-pressure mercury lamp through the holes in the shadow mask to a different position of the photosensitive thin layer from the previous exposure.

Furthermore, by the same operation, a photosensitive thin layer,
After irradiating light to a position different from the previously exposed position, a red luminescent phosphor was applied by dusting.

In this way, a mosaic-like phosphor coating layer that can be used as a phosphor surface of a color cathode ray tube was manufactured. It was confirmed that the phosphor coated layer produced in this manner became insoluble in water when exposed to a mixed gas of ammonia and water for several seconds.

On the other hand, when the above-mentioned back exposure was not performed, it was necessary to perform each exposure for 60 seconds at an illuminance of 10,000 lx through a shadow mask.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram for explaining the present invention.

Claims (1)

[Scope of Claims] 1. A method for forming a patterned powder coated layer on the surface of a substrate, in which an aromatic diazonium salt or a photosensitive composition that becomes tacky upon exposure and contains an aromatic diazonium salt as a photosensitive component is transparent. A first step of coating the substrate surface to form a thin layer, a second step of exposing the thin layer to light from the transparent substrate side within a range where the surface of the thin layer does not become sticky, and a second step of exposing the thin layer to light from the surface side. A third step in which the surface of the exposed area is made sticky by exposing the exposed area to light, and a fourth step in which powder particles are brought into contact with the exposed thin layer and the exposed area receives the powder particles. Characteristic method for forming a patterned powder coating layer.