JPS6014053B2 - Phosphor recovery and purification method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a novel method for recovering and purifying crab photophores.

More specifically, we will discuss how to efficiently collect, purify, and recycle the scale phosphor coating process using a honey phosphor slurry, especially the cleaning water and/or developing water used in the manufacturing process of luminescent screens for color cathode ray tubes. The present invention relates to a method for collecting and purifying crab photons that can be used. Hereinafter, a method for manufacturing a luminescent screen will be explained using a method for manufacturing a luminescent screen for a color cathode ray tube as a representative example.

The luminescent screen of a color cathode ray tube, for example, is made by repeatedly applying and drying a photosensitive phosphor slurry forming three types of light emitting elements G, B, and R on a face panel to form a photosensitive phosphor coating. This coating film is exposed to light to form a latent image of the light emitting elements, and this is developed to expose the light emitting elements.

Next, the process of forming a light emitting element in the manufacturing process of a light emitting screen for a color cathode ray tube and the light emitting screen for a color cathode ray tube will be explained using the drawings.

FIG. 1 is a flowchart of a process for forming a light emitting element in a process for manufacturing a light emitting screen for a color cathode ray tube.

FIG. 2 is a partially cutaway explanatory diagram showing a luminescent screen of a color cathode ray tube.

FIG. 3 is a partially enlarged explanatory diagram showing a luminescent screen of a color cathode ray tube.

In FIGS. 2 and 3, 1 is the face panel of a color cathode ray tube, 2 is a light emitting element formed on the face panel 1 [2G, 2B and 2R are three types of light emitting elements],
3 is a skirt portion of the face panel 1.

First, the crab phosphor particles to be applied are suspended in pure water, and then polyvinyl alcohol, ammonium dichromate, a dispersant,
After adding an antifoaming agent, a sensitizer, etc. to make a photosensitive phosphor slurry, the photosensitive phosphor slurry is applied onto the washed and dried face panel 1 as shown in FIGS. 1 to 3, A photosensitive crab coating film is formed by drying, and this coating film is exposed to light through a shadow mask to form a latent image of the light emitting elements 2 (2G, 2B and 2R are three types of light emitting elements). This is developed by spraying pure water to expose the light emitting element 2.

Of the photosensitive crab phosphor slurry applied in this step, the photosensitive crab phosphor slurry remaining on the skirt portion 3 of the face panel 1 is washed and removed with washing water, and is carried out together with the washing water in the crab phosphor recovery step. During development, the unexposed portion of the photosensitive crab photo-material slurry is sent together with developing water to a crab photo-material recovery step. The washing water and/or developing water containing this photosensitive crab photoform slurry is dehydrated using a centrifuge, and the resulting dehydrated product is washed with water, decantation is repeated, and dehydrated using a centrifugal separator again. It is reused as a material for photosensitive crab slurry. However, as mentioned above, it is prepared using crab photons recovered by repeated dehydration and washing from washing water and/or developing water containing photosensitive crab photons slurry, that is, recovered crab photons recovered by conventional methods. In the photosensitive crab photo coating film formed using the photosensitive crab photo slurry, defects such as oil spots and pinholes occur in the photosensitive crab photo coating film. There is a drawback.

Next, using drawings, we will explain the photosensitive crab phosphor coating film that is formed on the face panel when using the photosensitive crab phosphor slurry prepared using the crab phosphor recovered by the conventional method. .

Figure 4 is a partial cutout showing the photosensitive backlight coating film formed on the face panel of a face panel using a photosensitive crab photon slurry prepared using crab photons recovered by a conventional method. It is an explanatory diagram.

In FIG. 4, 1' is a face panel of a color cathode ray tube, 2 is a light emitting element formed on the face panel 1,
3 is a skirt portion of the face panel 1, 4 is a circular extremely thin portion of the photosensitive halo coating, and 5 is a striped extremely thin portion of the photosensitive halo coating.

In other words, in the process of manufacturing a luminescent screen for a color cathode ray tube using a photosensitive halophoton slurry prepared using crab phosphor recovered by the conventional method, the face panel is finally manufactured as shown in FIG. 4. The photosensitive crab phosphor coating film formed by applying the photosensitive crab phosphor slurry above in step 1 has a thin circular shape with a diameter of about 2 sides, a part 4 and/or a length about 5 sides. , Part 6, where the coating film becomes extremely thin, looks like a 0.5 to 1 willow streak.

Since these coating films are extremely thin and there are almost no crab phosphor particles in the defective parts 4 and 5, when the light emitting element 2 is formed by the photo printing method, a part of the light emitting element 2 is missing. The condition will be the same as that of the above condition, and a normal light emitting element 2 cannot be obtained. Therefore, the photosensitive crab photoform slurry prepared using the recovered crab photoforms had to be discarded as a defective product, which was extremely uneconomical. The present invention eliminates the above-mentioned disadvantages and provides a method for producing photosensitive crab coatings from washing water and/or developing water containing photosensitive crab slurry used in the manufacture of luminescent screens such as color cathode ray tubes. The present invention provides a method for recovering and refining crab photons that can be reused as a material for photosensitive crab photons slurry without producing the defective parts.

The present inventors have disclosed that photosensitive crab phosphors prepared using crab phosphor recovered from washing water and/or developing water containing photosensitive phosphor slurry used in the manufacture of luminescent screens such as color cathode ray tubes, etc. As a result of a thorough investigation into the causes of the defects mentioned above in the presses that use body slurry, we found that
It was revealed that the cause of this was due to surfactants such as dispersants and antifoaming agents added during the preparation of the photosensitive crab slurry.

In other words, these surfactants are thermally denatured while adsorbed to the crab photons during the drying process of the coating film formed by applying the photosensitive crab photons slurry or the centrifugation step in the recovery process of the crab photosensors. It is presumed that the above-mentioned defects occur in the photosensitive crab phosphor coating as a result of interaction with other substances, such as oil, mixed in the photosensitive crab phosphor slurry. This is because the photosensitive crab phosphor coating film formed on the paint using the photosensitive crab phosphor slurry prepared using the crab phosphor recovered from the photosensitive crab phosphor slurry that does not contain a surfactant. This is because the defective portion does not occur. However, based on the above findings, the present inventor has conducted extensive research on methods for removing degraded surfactants, and as a result,
The inventors have discovered that the degraded surfactant can be efficiently removed by using isotactic polypropylene as the material for the removal material, and have completed the present invention.

That is, the present invention provides a method for recovering crab photons from washing water and/or developing water containing a crab photon slurry used in a photographic printing method, in which the recovered crab photons are washed with water one or more times and then recovered. Recovery of crab phosphor, characterized by reacting the crab phosphor suspended in pure water with an isotactic polypropylene nonwoven fabric or filtering it using an isotactic polypropylene furnace cloth. This relates to a purification method, and includes photosensitive crab light prepared using conventionally recovered fin photons by treating them with an isotactic polypropylene nonwoven fabric or furnace cloth during purification of the recovered fin photons. The drawbacks mentioned above, such as the occurrence of circular or streak-like extremely thin spots on the photosensitive crab coating film formed on the face panel as in body slurry, have been completely eliminated, and the recovered honey has been completely eliminated. Even if the phosphor is reused as a material for photosensitive nectar slurry, extremely thin areas in the form of circles or streaks occur on the phosphor coating formed on the face panel. A very remarkable effect is obtained in that a photosensitive honey phosphor slurry can be obtained which can form a uniform photosensitive phosphor coating film without any oxidation.

In the method of the present invention, the photosensitive crab phosphor slurry to which the crab phosphor is recovered and purified includes, for example, copper and aluminum co-activated zinc sulfide green-emitting crab phosphor, europium-activated yttrium oxysulfide red-emitting honey. A typical photosensitive phosphor slurry used in the production of luminescent screens such as color brown screens made of phosphors and the like can be mentioned.

In the nonwoven fabric or furnace cloth made of isotactic polypropylene using the method of the present invention, the physical properties of the isotactic polypropylene that is the base material include a specific gravity of 0.85 to
0.95, average degree of polymerization 1000~loo0 or higher melting point 165
-176°C and a softening point of 150-154°C.

Next, one embodiment of the method for recovering and purifying crab photons of the present invention will be described with reference to the drawings.

FIG. 5 is an explanatory diagram showing one embodiment of the apparatus used in the method for recovering and purifying crab photophores of the present invention.

In Figure 5, 6 is an isotactic polypropylene non-woven fabric, 7 is a stainless steel tank, 8 is a fly azusa feather, 9
is the motor for Azusa.

First, the photosensitive crab phosphor slurry collected together with washing water and/or developing water in the process of forming a light emitting element is dehydrated through a centrifugal separator, and the resulting crab phosphor cake is placed in tank 7, and purified water is added thereto. Then, start the loss motor 9 and wash the crab light body with water by using the deep floating feather 8.

After the crab light body cake is completely dispersed in the water, stop the chick azusa and let the crab light body float. Next, remove the upper light solution by decantation, add pure water again, rinse, and wash the crab light body with water. After the crab phosphor is completely suspended, the isotactic polypropylene nonwoven fabric 6 is hung as shown in FIG. Then, the crab photoluminescent suspension A is treated in a far-D separator to recover the crab photoforms. Furthermore, in the photoreceptor recovery and purification method of the present invention, the nectar suspension is filtered using an isotactic polypropylene oven cloth instead of oven paper.

To complete the filtration process, the filtrated fibers are backwashed, peeled off from the isotactic polypropylene nonwoven fabric, and resuspended in pure water. However, the crab photoreceptor suspension was
It is passed through a furnace using a separator and the phosphor is recovered. The recovered crab phosphor purified by the method of the present invention is dried and then reused alone or mixed with new crab phosphor to prepare a photosensitive bulk phosphor slurry.

In the method of the present invention, the photosensitive crab photon slurry prepared using the recovered crab photon that has been purified by contacting it with an isotactic polypropylene nonwoven fabric or oven cloth as described above can be recovered by a conventional method. As in the photosensitive crab photo material slurry prepared using the prepared crab photo material, the above-mentioned defective spots do not occur in the photosensitive crab photo material coating film formed on the face panel.

This is thought to be because the altered surfactant is adsorbed to the isotactic polypropylene that is the base material of the nonwoven fabric or furnace cloth. Therefore, according to the method of the present invention, even if the photosensitive crab photon slurry is prepared using the recovered crab photon, the photosensitive honey photon slurry prepared using the crab photon recovered by the secondary method is As the photosensitive phosphor coating is extremely thin and no parts are generated, the photosensitive phosphor slurry can be used effectively, which is beneficial for reducing the cost of color cathode ray tube luminescent screens. In particular, when the method of the present invention is applied to a slurry of red light-emitting phosphors consisting of rare elements, the cost reduction of the luminescent screen is significant since red light-emitting phosphors are expensive. The method of the present invention is also effective for removing surfactants that have been thermally or chemically altered in the photosensitive crab photon slurry, and the photosensitive crab photon slurry is isolized as shown in FIG. It can be applied to restore normal photosensitive crab slurry by interacting with a tactical polypropylene nonwoven fabric.

However, since unaltered surfactant is also adsorbed and removed during this process, it is necessary to add new surfactant. Next, the method for recovering and purifying crab photons of the present invention will be specifically explained with reference to Examples.

Example 1 Copper and aluminum co-activated zinc sulfide green luminescent material recovered together with washing water and developing water in the light emitting element formation process in the luminescent screen manufacturing process for color cathode ray tubes was dehydrated using a centrifugal separator. The crab light body cake 80k9 was placed in a stainless steel tongue outer container for 300 yen.
150 ml of deionized water was added to this and the crab was washed with water.

After washing with water, it was left to stand still to allow the crab phosphor to evaporate, and the supernatant liquid was removed by decantation. Then add deionized water 1 again
Isotactic polypropylene (specific gravity: 0.91, average degree of polymerization: 900Q, melting point: 170'C, softening point 150qo)
Two pieces of non-woven fabric [manufactured by Mitsubishi Rayon■, trade name: Betrel A] were hung as shown in Figure 5, and then drying was started, and after the crab phosphors were completely suspended, hanging was continued for 2 hours. . This phosphor suspension was sent to a centrifuge for dehydration, and the resulting crab phosphor cake was then dried to collect purified crab phosphor. Then, the purified recovered crab photon and the new green crab photon were mixed (weight ratio 50:50) to prepare a photosensitive crab photon slurry. The prepared photosensitive phosphor slurry was applied onto the face panel of a color cathode ray tube to form a photosensitive phosphor coating, but the resulting photosensitive phosphor coating had circular and striped shapes. There were no areas where the paint film became extremely thin.

However, in the case of a crab phosphor slurry prepared using crab phosphor recovered by a conventional method that does not use an isotactic polypropylene nonwoven fabric, approximately 70% of the resulting photosensitive phosphor coating is obtained. %, circular or streak-like extremely thin areas of the paint film were observed.

Example 2 The europium-activated yttrium oxysulfide red light-emitting material recovered together with washing water and developing water in the light-emitting element formation process in the light-emitting screen manufacturing process for color cathode ray tubes was dehydrated using a centrifuge. Put 300ml of halo cake 80k9 into the stainless steel tank,
150 ml of deionized water was added to this, and the crab phosphata was washed with water.

After washing with water, it was allowed to stand still to allow the crab phosphor to settle, and the top light solution was removed using a siphon. Next, 150 ml of deionized water was added again to suspend the crab phosphor, and the crab phosphor suspension was then poured into isotactic polypropylene (specific gravity: 0.91, average molecular weight: 10,000, melting point: 170°C). , Softening point: 1st string.0] Furnace cloth [Mitsubishi Rayon ■, product name Betrel A]
The filtered crab phosphatide was filtered using deionized water and resuspended by backwashing with deionized water.

This crab photon suspension was sent to a centrifuge for dehydration, and the resulting crab photon cake was then dried to collect purified crab photon. Next, a photosensitive crab photon slurry was prepared using the purified recovered crab photon.

The prepared photosensitive crab phosphor slurry was applied onto the face panel of a color cathode ray tube to form a photosensitive crab phosphor coating, but the resulting photosensitive crab phosphor coating had circular and streak-like shapes. There were no areas where the paint film became extremely thin.

However, in the photosensitive honey phosphor slurry prepared using the crab phosphor recovered by the conventional method that does not use isotactic polypropylene furnace cloth, about 90% of the resulting photosensitive phosphor coating is Extremely thin paint film in the form of circles or streaks,
This photosensitive crab slurry had to be discarded.

[Brief explanation of the drawing]

Figure 1 is a process diagram for forming a light emitting element in the manufacturing process of a color cathode ray tube's luminescent screen, Figure 2 is a partially cutaway explanatory diagram showing a color cathode ray tube's luminescent screen, and
The figure is a partially enlarged explanatory diagram showing the luminescent screen of a color CRT. FIG. 5 is a partially cutaway explanatory view showing the photosensitive crab photon coating film formed, and FIG. 5 is an explanatory view showing an embodiment of the apparatus used in the crab photon recovery and purification method of the present invention. (Main symbols in the drawing), 1: face panel of color cathode ray tube, 2: light emitting element formed on the face panel,
3: Skirt portion of the face panel, 4: Thin circular extremely photosensitive crab photo coating, portion, 5: Thin striped extremely photosensitive crab photo coating, portion, 6: Isotaku. Non-woven fabric made of thick polypropylene. 2 figures, 5 figures, 4 figures, 5 figures

Claims (1)

[Claims] 1. In a method for recovering phosphors from washing water and/or developing water containing a phosphor slurry used in a photographic printing method, after washing the recovered phosphor with water one or more times, 1. A method for recovering and purifying a phosphor, characterized in that the phosphor is suspended in pure water and treated with an isotactic polypropylene nonwoven fabric, or filtered using an isotactic polypropylene filter cloth.