Photoresist and method of manufacturing the color cathode-ray tube by use thereof

Photoresist for forming the phosphor screen of color cathode-ray tube made up of the composition rate of pure water 10-50%, polyvinyl alcohol 5-30%, dichromate potassium salt 0.5-5%, diethylene glycol 0.5-10%, ethylene glycol 0.5-5%, urea 0.5-10%, acetamide 0.5-5%, butanediol 0.5-10%, paraaldehyde 0.5-5%, dioxane 0.5-5%, a surfactant 0.5-5%.

FIELD OF THE INVENTION 
The present invention relates to photoresist for forming the phosphor 
screen of the color cathode-ray tube and the method of manufacturing the 
phosphor screen by use thereof. 
BACKGROUND OF THE INVENTION 
In the inner side at the face plate of the color cathode-ray tube, three 
color phosphor patterns are arranged and so form the phosphor screen. 
As the method these phosphors are spread to form a designated pattern in 
the inner side of the face plate, it is done slurry spread method by using 
photoresist blended with the phosphor and dry method by sensitizer with 
diazonium salt, diazonium salt is resolved to be exposed to mercury 
excited ultraviolet and then have adhesion in that ZnCl.sub.2 absorbs the 
moisture in the air. 
The method of manufacturing the sensitizer by using these methods is 
disclosed Korean Patent 83-3421, filed July 25, 1983 and Korean Patent 
Application No. 83-3645, filed Aug. 4, 1983, etc. 
As the former slurry spread method develops by washing unexposed part after 
spreading the phosphor slurry to the inner side of the face plate and 
exposing the only designated part through the shadow mask, there is an 
disadvantage that the exposure time is long because the photosensitivity 
is low and that it is unable to obtain the minute and phosphor pattern 
because exposed ultraviolet causes light scattering on the surface of the 
phosphor. 
As the latter dry method is to spread the sensitizer in the inner side of 
the face plate and dry, then adhere by exposing and scattering the 
phosphor, where in wash phosphor remaining in unexposing area by blowing 
air and to form by destroying the tack which reveal the exposed sensitizer 
through dose of roading materials, it is able to obtain the good phosphor 
pattern than the predescribed slurry spread method, but it is difficult to 
remove the phosphor remaining to unexposed area clearly on account of 
removing by blowing air, there occurs color-remaining at the next time to 
spread the fluorescent film. 
The clearness of the picture at the color cathode-ray tube is influenced by 
how fine, straight, right trio color phosphor patterns of red, blue, green 
can be formed. 
SUMMARY OF THE INVENTION 
The object of the present invention is to provide photoresist that is no 
variation of the tack after exposure and dry, dry temperature range to be 
wide. 
The other object of the present invention is to provide method of forming 
the phosphor screen obtainable systematic and clear high-fine phosphor 
screen by using predescribed photoresist. 
According to this, the photoresist of the present invention is made up at a 
rate pure water 10-50%, polyvinyl alcohol 5-30%, dichromate salt 0.5-5%, 
diethylene glycol 0.5-5%, ethylene glycol 0.5-5%, urea 0.5-5%, acetamide 
0.5-5%. Butanediol 0.5-10%. paraaldehyde 0.5-5%, dioxane 0.5-5%, a 
sulfactant 0.5-5%. 
And the method of forming phosphor by using predescribed composition is 
followed to spread predescribed composition in the inner side of the face 
plate of the color cathode-ray tube and expose, dry, then adhere to 
exposed area by light scattering the phosphor, after removal of the 
phosphor of unexposed area by water, process flow of contraction, 
adherence the phosphor screen by managing with boric acid.

DETAILED DESCRIPTION OF THE INVENTION 
The photoresist of the present invention consists of the following 
material. 
Polyvinyl alcohol: 5-30% is added. This has the specific character 
photo-bridging by Cr.sup.+++ reduced to receive the light of the 
wavelength 364 nm. That is to say, the carboxyl radical which is resolved 
product found finally during oxidation-reduction reaction forms Cl.sup.+++ 
and composition of octahedron. 
This carboxyl radical has the covalent bond as the ionized radical 
congelated with .alpha., .beta. on the structure. This point of the 
covalent bond is saturated by ionized radical of other polyvinyl alcohol 
chain and is formed 3-dimensional light bridging, then reduces fairly the 
solubility to water. 
Dichromate salt; 0.5-5% is added. It maintains the sensitivity to light 
stable from heat or the other outer effect by reaction with polyvinyl 
alcohol. 
At the present invention, the best result is obtained to use dichromatic 
potassium salt as dichromate salt. 
Diethylene glycol; 0.5-5% is added, a plasticizer is added. Ethylene 
glycol; 0.5-5% is added, sensitivity to light and condition of drying are 
determined. 
Urea and acetamide; 0.5-5is added. These materials that contain amine keep 
them dry at the moment of forming the fluorescent layer and have 
crystallization of the phosphor good by absorbing the moisture in the air. 
First class reagent of Hayashi, Japan was used in the present experiment. 
Butandiol; 0.5-10% is added. This operates as plasticizer obtained to whole 
composition. 
Paraaldehyde and dioxane; They control the speed of evaporation of the 
composition operated as plasticizer and keep the condition of dry of resin 
film sensitive to light uniformly. 
Surfactant: It is obtained by resolving Tamol 731SD sodium salt of 
polymeric carboxylic acid which can be obtained from American Rohm & Haas 
Co. with hot water 100 ml and dosing triton CF-104-5 drops. 
The composition of predescribed materials is made up as follows. 
First, stirred the diluted polyvinyl alcohol solution with pure water 
continuously at room temperatures, pour diethylene glycol and 
ethyleneglycol. 
After stirring for 10 minutes and mixing cell, add area, acetamide, 
butanediol in turns. 
On stirring continuously, mix paraaldehyde and dioxane and then dose a 
surfactant. 
The composition obtained is filtered by 400 mesh and used. The tack of the 
composition and the adjustment of the solid body are controlled by the 
adjustment of polyvinyl, pure water in accordance with distribution 
density of the fluorescent film. 
The whole content of plasticizer is limited to 20-50%. 
In the content of plasticizer is under 20 w/v %, the phosphor becomes dry 
easily and the sticking density of the fluorescent film decreases, in case 
of exceeding 50 w/v % pattern does not form on account of non dry. 
Also, predescribed composition is used as the spread of red, blue 
fluorescent film as it is, in case of green fluorescent layer it is used 
to add cohesion to increase the adhesion with the glass surface. It is 
used American Dupon Co. Ludox AM at a range 0.5-5% as a cohesion. 
The method of forming phosphor screen with predescribed composition is dome 
as the drawing of FIG. 1. 
We spread predescribed composition at the inner side of the face plate (2) 
and form first sensitivity to light(4). 
Then fix the green fluorescent layer mask(6) to the face plate(2) and 
expose. The exposed part at the first sensitivity to light(4) has the tack 
and insolubility to water, then it we eject phosphor powder, green 
fluorescent film is formed. 
The content of plasticizer of predescribed composition is 20-50 w/v %, so 
the adhesion density of the phosphor become very high. And if we collect 
exceeding scattered phosphor with a suitable capturing means like a vacuum 
inhaler, it is able to collect excess phosphor and protect the 
contamination of the phosphor. If we wash this with pure water and wash 
the phosphor of the unexposed part and remaining phosphor perfectly, green 
fluorescent layer pattern(8') remains. If we wash this with boric acid 
water, the fluorescent film pattern is contracted and adhered, it is 
obtainable an ordered and clear green fluorescent film pattern. Boric acid 
water was used 2.5%. solution. 
Red, blue fluorescent film pattern is used predescribed composition as it 
is and is obtained by the same method with green fluorescent layer 
pattern. 
The enlarged photograph of the fluorescent film pattern obtained by this 
way is FIG. 2. The magnification of fluorescent film pattern obtained by 
the former slurry spread method is shown in the photograph of FIG. 3. The 
fluorescent film pattern of the present invention displays more orderly 
and clear with the naked eye.