JP3029851B2 - How to create phosphor screen - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for forming a fluorescent screen such as a color picture tube.

(Prior Art) The phosphor film of a color picture tube is formed by applying a phosphor slurry on the inner surface of a face plate, drying, applying a shadow mask having a predetermined pattern, exposing it to light, and then washing it with warm water. The phosphor in the unexposed portions is removed to form phosphor dots or stripes. By this optical printing method, green, blue and red light emitting phosphor films are sequentially formed.

The photosensitive phosphor slurry used here is composed of a slurry in which phosphor powder, a photosensitive resin, and a sensitizer are mixed with water, and further improves the dispersibility of the phosphor and suppresses foaming of the slurry. Therefore, a small amount of nonionic surfactant may be added.

JP-A-53-45965 discloses that the above-mentioned surfactant is deposited on a face plate in a phosphor slurry containing a pluronic nonionic surfactant for the purpose of improving dispersibility and film forming property. In order to prevent poor color mixing, poor coarse film, poor coating and poor thermal fogging due to precipitation, a sulfate-based surfactant manufactured by Toho Chemical Co., Ltd. was used against a Pluronic type nonionic surfactant such as Pluronic L-92. It describes that an anionic surfactant of the agent Alscope LP-30 or a nonionic surfactant of Nonion LT-221 manufactured by NOF Corporation is used in combination.

Japanese Patent Application Laid-Open No. Sho 64-74286 discloses that, in order to improve the adhesive strength of a phosphor, a phosphor slurry containing a polyacrylate or polymethacrylate compound is added to Daiichi Kogyo Seiyaku Co., Ltd. It is described to add a nonionic surfactant of Tween-20 manufactured by Tsubaki Corporation.

Incidentally, the cloud points of Pluronic L-92 and Nonion LT-221 described in JP-A-53-45965 are 2
6 ° C and 85 ° C, described in JP-A-64-742286.
The cloud point of Tween-20 is above 100 ° C.

(Problems to be Solved by the Invention) However, the above-mentioned surfactant has a certain effect on the dispersibility of the phosphor, the defoaming property of the slurry, the defect of the fluorescent film, etc. Since the substance was separated and bleeding, unevenness, dropping and the like were generated from the face plate, it was not always possible to obtain a sufficiently good phosphor coating film.

The present invention uses a phosphor slurry which solves the above-mentioned disadvantages, suppresses the separation of oily substances, and has excellent dispersibility of the phosphor and defoaming property of the slurry, in consideration of the balance with the application conditions. By doing so, it is intended to provide a method capable of producing a high quality phosphor screen.

(Means for Solving the Problems) The present invention provides a method for preparing a phosphor screen by applying a phosphor slurry containing a phosphor powder, a binder and a surfactant to a substrate, wherein the surfactant has a cloud point of Using a nonionic surfactant having a temperature in the range of 30 to 75 ° C., the temperature of the substrate in the range of 29 to 50 ° C., and a temperature lower than the cloud point temperature of the nonionic surfactant. A method for producing a phosphor screen, characterized in that the phosphor is adjusted and coated on the substrate.

As the nonionic surfactant usable in the present invention, a polyethylene glycol type nonionic surfactant, in particular, a polypropylene glycol ethylene oxide adduct, a polyoxyalkylene polyol, a polyoxyethylene polyoxypropylene block polymer, a polyoxyethylene alkyl ether, Those containing polyoxyethylene alkylphenyl ether or the like as a main component and having the above cloud point are preferred. In this case, the cloud point was measured with a 1% by weight aqueous solution of a surfactant.

Further, the phosphor slurry of the present invention, in addition to the above essential components, well-known anionic or cationic surfactant, 75
A nonionic surfactant having a cloud point exceeding ℃, a sensitizer,
Preservatives and other additives (such as acrylic emulsion)
Can be added as appropriate.

(Effect) The present inventors, while examining the problems of the phosphor slurry containing the nonionic surfactant, focused on the cloud point of the nonionic surfactant.
A patent application has been filed for the invention of a phosphor slurry containing a nonionic surfactant having a cloud point in the range of not lower than 75 ° C. and preferably not higher than 32 ° C. and 60 ° C.

Here, the cloud point is a temperature at which when a transparent aqueous solution of a nonionic surfactant is gradually heated, the surfactant is suddenly separated as fine droplets, and the whole becomes cloudy. Upon cooling, the surfactant dissolves again.

By the way, the phosphor slurry is used at room temperature, but if the phosphor film forming step is examined in detail, the next phosphor slurry is applied to the face plate washed with hot water in the developing step for forming the phosphor film in the preceding stage. Therefore, the phosphor slurry may be heated on the heated face plate surface, heated by a pump or the like in a slurry supply system, or the adjusted slurry may be left for a long time. I do. At this operating temperature,
The temperature of the face plate surface becomes the highest,
There is a risk of exceeding the cloud point of the surfactant.

On the other hand, since the phosphor slurry maintains the dispersibility of the phosphor even by the nonionic surfactant attached to the phosphor surface, the surfactant loses surface activity when the surfactant has a cloud point or higher. Secondary aggregation begins between the phosphor particles. Even though the nonionic surfactant aqueous solution is once heated to a cloud point or higher and becomes cloudy, the surfactant can be dissolved by cooling, but the secondary aggregated phosphor slurry is cloudy. It is not easily deagglomerated only by cooling to below the point, and if it is applied as it is, the above described fluorescent film defect occurs. Also, if the temperature of the face plate surface is higher than the cloud point, the slurry temperature will exceed the cloud point on the face plate surface during application, causing the aggregation of phosphors and contamination of the face plate surface due to the insolubilization of the nonionic surfactant. As a result, a rough film defect of another phosphor screen such as a repelling defect also occurs.

Further, when a nonionic surfactant having a cloud point of more than 75 ° C. is used, the defoaming effect and the like are reduced, and defects such as cissing caused by air bubbles occur again.

However, it has been found that when the temperature of the face plate surface largely deviates from the cloud point temperature in addition to the cloud point of the nonionic surfactant, the above-mentioned effects of the nonionic surfactant cannot be enjoyed. Therefore, when examining the relationship between the degree of the divergence and the effect, the range in which the effect can be enjoyed is, in using the specific nonionic surfactant, the temperature of the face plate surface is set to 20 to 50 ° C. It has been found that it is preferable to keep the temperature within the range and below the cloud point of the nonionic surfactant used. At this time, it was found that the temperature of the face plate was preferably closer to the cloud point.

Therefore, in the present invention, 30 ~ 75 ℃, preferably 32 ~ 60 ℃
A nonionic surfactant having a cloud point in the range of, the above temperature lower than the temperature of the cloud point, more preferably 30 to 45 ° C
By adjusting the temperature of the face plate surface, it is possible to apply the phosphor slurry while securing the dispersibility of the phosphor and the defoaming property of the slurry, thereby forming a high quality phosphor film. .

(Example 1) ZnS: Cu, Al green light emitting phosphor 100 parts by weight Pure water 150 parts by weight Polyvinyl alcohol 10% aqueous solution 90 parts by weight Sodium dichromate 10% solution 8 parts by weight Sensitizer 2 parts by weight Anionic surfactant 20% solution 0.05 parts by weight Polypropylene glycol ethylene oxide adduct 5
% Solution (cloud point: 34 ° C.) 1 part by weight The above materials are thoroughly mixed and stirred to prepare a green light emitting phosphor slurry, 10 ml of the slurry is put in a 30 ml test tube, and a rubber stopper is put on the tube, and then up and down by hand. Was shaken 30 times, and allowed to stand for 5 minutes, and then the height of the foam was measured. The remaining slurry was placed in a plastic container and rolled for 16 hours, but no foam was generated. While maintaining the slurry at 23 ° C. and adjusting the temperature of the face plate surface to 31 ° C., 14
It was applied to 10 inch panels, and the number of panels having defective foaming of the fluorescent film and defective repelling was examined.

As a result, in the foaming test, only one layer of foam was recognized,
Excellent defoaming properties of the slurry were confirmed. Also, the fluorescent film
All 10 sheets were extremely good, with no defective foaming and no repelling.

(Comparative Example 1) The nonionic surfactant was omitted from the raw materials of Example 1,
A phosphor slurry was prepared and subjected to a foaming test in the same manner as in Example 1. Further, the remaining phosphor slurry was placed in a plastic container and rolled for 16 hours to remove generated bubbles, and then applied to a panel in the same manner as in Example 1 to perform an application test of a phosphor film.

As a result, in the foaming test, the foam height was 31 mm.
In the application test of the fluorescent film, although there was no repelling defect, defective foaming was observed in 2 out of 10 sheets.

(Comparative Example 2) In the raw material of Example 1, a nonionic surfactant was used at a cloud point.
A phosphor slurry was prepared by changing to polypropylene glycol ethylene oxide adduct at 18 ° C., and a foaming test and a coating test of a phosphor film were performed in the same manner as in Example 1.

As a result, in the foaming test, only one layer of foam was recognized, and the defoaming property of the slurry was recognized. In addition, in the coating test of the fluorescent film, although there was no foaming defect, five out of ten sheets had defective cissing.

(Comparative Example 3) In the raw material of Example 1, a nonionic surfactant was used at a cloud point.
A phosphor slurry was prepared by changing to polyoxyethylene sorbitan monolaurate at 100 ° C., and a foaming test was performed in the same manner as in Example 1 and a coating test of a phosphor film from which bubbles were removed in the same manner as in Comparative Example 1.

As a result, in the foaming test, the foam height was 26 mm, and in the coating test of the fluorescent film, there were no cissing defects, but two foaming defects were recognized.

(Comparative Example 4) In Example 1, only the temperature of the face plate surface was set to 39.
C., the prepared phosphor slurry was applied to the face plate surface, and an application test was performed. As a result, two sheets were defective and no foaming was defective, but a coarse film defect occurred on all panels. .

(Example 2) ZnS: Ag blue light emitting phosphor with a cobalt aluminate blue pigment
100 parts by weight Pure water 150 parts by weight Polyvinyl alcohol 10% aqueous solution 90 parts by weight Sodium dichromate 10% solution 8 parts by weight Sensitizer 2 parts by weight Anionic surfactant 20% solution 0.5 parts by weight Polypropylene glycol ethylene oxide adduct 5
% Solution (cloud point: 48 ° C) 4 parts by weight The above raw materials are thoroughly stirred and mixed to prepare a blue light emitting phosphor slurry, 10 ml of the slurry is placed in a 30 ml test tube, and a rubber stopper is put on the tube, and then up and down by hand. Was shaken 30 times, and allowed to stand for 5 minutes, and then the height of the foam was measured. The remaining slurry was placed in a plastic container and rolled for 16 hours, but no foam was generated. This slurry was kept at 27 ° C, and the temperature of the face plate was adjusted to 41 ° C, and applied to 10 14-inch panels by the spin coating method, and the number of panels with foaming defects and crawl defects of the fluorescent film occurred. Was examined.

As a result, in the foaming test, only one layer of foam was recognized, and the excellent defoaming property of the slurry was confirmed. In addition, no defective foaming and no repelling defects were observed in all of the 10 fluorescent films, and extremely good fluorescent films were obtained.

(Comparative Example 5) The nonionic surfactant was omitted from the raw materials of Example 2,
A phosphor slurry was prepared and subjected to a foaming test in the same manner as in Example 1. Further, the remaining phosphor slurry was placed in a plastic container and rolled for 16 hours to remove generated bubbles, and then applied to a panel in the same manner as in Example 1 to perform an application test of a phosphor film.

As a result, in the foaming test, the foam height was 36 mm.
In the application test of the fluorescent film, although there was no repelling defect, defective foaming was observed in 2 out of 10 sheets.

(Comparative Example 6) In the raw material of Example 1, a nonionic surfactant was used at a cloud point.
A phosphor slurry was prepared by changing to a polypropylene glycol ethylene oxide adduct at 25 ° C., and a foaming test and a coating test of a phosphor film were performed in the same manner as in Example 2.

As a result, in the foaming test, only one layer of foam was recognized, and the defoaming property of the slurry was recognized. In addition, in the application test of the fluorescent film, although there was no foaming defect, all 10 sheets were defective.

(Comparative Example 7) In Example 2, only the temperature of the face plate surface was changed to 53.
C., the prepared phosphor slurry was applied to the face plate surface, and an application test was carried out. As a result, four sheets were defective and no defective foaming was found. .

(Effect of the Invention) According to the present invention, by adopting the above configuration, a phosphor slurry having excellent dispersibility of the phosphor and defoaming property of the slurry can be applied to the face plate surface under optimal conditions. The formation of a high quality fluorescent film was made possible.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Morio Hayakawa 1060 Narita, Odawara City, Kanagawa Prefecture Inside Kasei Optonics Co., Ltd. (56) References JP-A-57-3343 (JP, A) JP-A-55-72339 (JP) JP, A) JP-A-53-45965 (JP, A) JP-A-64-74286 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 9/227

Claims (1)

(57) [Claims] 1. A method of preparing a phosphor screen by applying a phosphor slurry containing a phosphor powder, a binder and a surfactant to a substrate, wherein the surfactant has a cloud point in the range of 30 to 75 ° C. Use the one containing nonionic surfactant in
A phosphor screen wherein the temperature of the substrate is in the range of 29 to 50 ° C., and the temperature is adjusted to a temperature lower than the cloud point temperature of the nonionic surfactant to be used, and a phosphor is applied to the substrate. How to create