JPS62252038A - Reclamation method of light absorption layer for cathode-ray tube - Google Patents

Abstract

PURPOSE:To make it possible to remove a defective fluorescent screen without using an oxidizing agent, producing no disorder in a light absorption layer of a black stripe type or a black matrix type,by soaking the face plate of a detective fluorescent screen placing the screen side facing downward in a pure water and applying ultrasonic waves from the lower side. CONSTITUTION:The face plate of a detective fluorescent screen produced in the manufacturing process of a cathode-ray tube is soaked in a pure water facing the fluorescent screen side downward, and ultrasonic waves of frequency 20 to 50 kHz are applied from the screen coating side at a rate 15 to 30 W per clean water 1l, to remove the phosphor, and the light absorption layer formed in the process prior to the fluorescent screen formation is reclaimed into a reusable condition. For example, after the fluorescent screen of a 14 size color cathode-ray tube of a black stripe type is formed in a slurry method with a diazo sensitizer, the face plate 1 is soaked in an ultrasonic wave cleaner 2 with a pure water therein, picked out about five minutes later, and washed by a water spray.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention relates to a method for recovering the face plate of a cathode ray tube, and in particular, to a method for recovering the face plate of a cathode ray tube, and in particular, a method for recovering the face plate of a cathode ray tube. The present invention relates to a method for regenerating a light absorption layer that allows the light absorption layer formed in a process to be reused as is.

(Prior art) In the past, when forming a phosphor screen, which is one of the manufacturing processes for color cathode ray tubes, blue, green, and red phosphors were each made of PVA.
, mixed with a photosensitizer such as ADC, spin-coated onto the inner surface of the face plate as a slurry, dried, and then baked and developed a predetermined pattern through a shadow mask. The process is repeated three times for blue, green, and red, and finally blue, A fluorescent screen with a predetermined pattern of green and red was formed. For defective phosphor screens that occurred during this process, the phosphor was removed, the face plate was reused, and the phosphor screen was formed again.

Conventionally, in the method of removing the phosphor and regenerating the face plate, the phosphor is removed by applying an oxidizing agent such as a mixture of hydrogen peroxide and aqueous ammonia to the phosphor screen of the face plate.

In addition, in the case of black stripe or black matrix type phosphor screens, in the method of applying a mixture of hydrogen peroxide and ammonia water, the carbon particles forming the black stripes and black matrix formed in the previous process also fluoresce. In some cases, they fell off during body removal work.

Furthermore, when a diazonium-based or bisazide-based photosensitizer is used as a photosensitizer in the slurry, it is impossible to remove the phosphor with a conventional mixture of hydrogen peroxide and aqueous ammonia; When using an agent such as a sodium hydroxide aqueous solution, the phosphor is removed but the black stripe and black matrix are also destroyed, making it unstable to recycle the light absorption layer (black stripe layer and black matrix layer). Met.

(Problems to be Solved by the Invention) A method for stably removing only the phosphor without peeling off the black stripe layer or the black matrix layer is proposed in, for example, Japanese Patent Laid-Open No. 57-3342.

The method involves wetting the entire surface of a defective luminescent screen with a 4% sodium hydroxide aqueous solution, allowing it to work for 1 minute, and then spraying at a water pressure of 0.5 kg/d.

On the other hand, depending on the conditions, this sodium hydroxide has the effect of removing even the graphite film, and its effect on cleaning the glass surface of the face plate is comparable to that of a hydrofluoric acid aqueous solution. There is.

All of the above methods use an oxidizing agent, and have the disadvantage that the oxidizing power is delicately adjusted.

In view of the above, the present invention is designed to remove only the defective phosphor from a defective phosphor screen without causing any abnormality in the light absorption layer of the black stripe or black matrix type. An object of the present invention is to provide a method for regenerating a light absorption layer that can remove the light absorption layer without using an oxidizing agent.

[Structure of the invention]

(Means for Solving the Problem) In the present invention, as a means of completely removing the phosphor while leaving the light absorption layer intact, a face plate with a defective phosphor screen is placed in a container filled with pure water with the phosphor screen facing downward. The method is to apply ultrasonic waves from the bottom toward the phosphor screen.

(Effect) Ultrasonic waves have the effect of exerting their cleaning power only on the phosphor, depending on the selection of the frequency and intensity.

(Example) After forming the phosphor screen of a 14-inch color cathode ray tube with a black stripe using a slurry method using a diazo photosensitive agent, the face plate (■) was made using a high-frequency output of 600 W containing about 30 Q of pure water as shown in Figure 1. , put it in an ultrasonic cleaner with an oscillation frequency of 28kHz, take it out for about 5 minutes, and spray it with water (
The pressure was 1 kg/aJ).

After that, ultraviolet rays were irradiated from the inner surface of the face plate, and examination under a microscope revealed that all of the phosphor had been removed, but the black stripe layer was not destroyed at all.

In addition, when a face plate with a similar fluorescent screen formed by an adhesive method was subjected to the same operation, all the fluorescent material was removed and the black stripe layer was not electroplated at all.

The oscillation frequency of the ultrasonic cleaner used in the present invention is 2 to 50k.
llz, and the high frequency output is 115~115 for the cleaning water IQ.
A power of 30 W is desirable, and outside this range there is a risk of stagnation of the phosphor and destruction of the light absorption layer.

〔Effect of the invention〕

As described above, according to the present invention, only the phosphor can be removed without destroying the black matrix and the black stripe layer, and the light absorption layer can be regenerated stably, which is effective in industrial production.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing an apparatus to which the present invention is applied. 1... Face plate, 2... Ultrasonic cleaning machine.

Claims (1)

[Claims] A face plate with a defective phosphor screen that occurred during the manufacturing process of a cathode ray tube is immersed in pure water with the phosphor screen side facing down, and then an ultrasonic wave with a frequency of 20 to 50 kHz is applied from the side where the phosphor screen is applied at a rate of 15 to 30 W per 1 liter of water. 1. A method for regenerating a light absorption layer of a cathode ray tube, characterized in that the light absorption layer formed in a step prior to the formation of a phosphor screen is regenerated into a reusable state by applying an electric current to remove the phosphor.