JPH03157479A - Frozen block of fluorescent slurry and production thereof - Google Patents

Abstract

PURPOSE:To obtain a frozen block having excellent dispersion stability and giving an excellent fluorescent layer by freezing a fluorescent slurry composed of a mixture of water and a fluorescent material at a specific ratio. CONSTITUTION:The objective frozen block is produced by freezing a fluorescent slurry obtained by mixing (A) water and (B) a fluorescent material composed of e.g. a sulfide fluorescent material containing at least one kind of element such as silver, copper or gold as a main activator and a rare-earth oxy sulfide or rare-earth aluminate fluorescent material, etc., containing at least one kind of element such as Eu or Tb as a main activator at a weight ratio (A:B) of 1:(1-100) [preferably 1:(4-50)]. The fluorescent slurry to be frozen is preferably incorporated with 0.001-2.0wt.% of a surfactant such as sodium napthalenesulfonate to secure the dispersion stability of the fluorescent material.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a frozen mass of a phosphor slurry suitable for storing and transporting a phosphor, as well as preparing a slurry for forming a coating film, and a manufacturing method thereof.

(Prior art) Conventionally, phosphors are synthesized by blending raw materials and firing, washing with water, dispersing and classifying, drying, storing in a container as a powder, and sending it to the user, where it is mixed with water, binder, etc. (Polyvinyl alcohol, dichromic acid, water glass, etc.) is added to prepare a phosphor slurry, which is then applied to cathode ray tubes, etc. Color TVs use a large amount of phosphor, so it is normal! It can be stored for a month, or up to a year (as it may be stored, long-term storage stability is also required).

However, the phosphor slurry undergoes changes in viscosity and P content over a period of several hours to several days, and a phosphor screen coated with the slurry may suffer from pinholes, uneven coating, cracks, and the like. This is thought to be due to changes in particle size distribution and slurry composition, as well as bacteria entering from the water or air. Therefore, it is not possible to store the phosphor as a slurry.1. As shown in section L, it is washed with water, dried, stored as a powder, transported, and reconstituted into a water slurry for use.

(Problems to be Solved by the Invention) Incidentally, in order to obtain a good phosphor screen, it is important that the phosphor particles are uniformly dispersed in medium-sized particles in the water slurry during coating.

Therefore, care must be taken to preserve single particles during the process of obtaining dry powder from the dispersed and classified water-washed slurry, the storage period of the powder, and the process of dispersing the powder in water to form a slurry again. operation is required. However, since phosphors are fine particles and highly active, even phosphors that have been dispersed and classified will re-agglomerate upon drying, and may also be pushed down by their own weight, making it impossible to avoid agglomeration. It was complicated.

Therefore, the present invention solves the above-mentioned problems, and the #J
The phosphor is transported from the phosphor manufacturer to the user's hands without causing any change in particle size distribution or slurry composition.
It is an object of the present invention to provide a frozen mass of phosphor slurry that can be stored and a method for producing the same.

(Means for Solving the Problems) The present invention provides a method for adjusting the weight ratio of water and phosphor from l=1 to I:IG.
A frozen lump of the phosphor slurry is obtained by adding a surfactant to the phosphor slurry adjusted to O, if necessary, and freezing this, and This is a method for producing a frozen lump of phosphor slurry, which is characterized by cooling and freezing the slurry in a small or moisture-impermeable container.

(Function) The phosphor slurry frozen mass of the present invention contains water and phosphor! rI
It is obtained by freezing a slurry adjusted to a m ratio in the range of 1:1 to 1:100. There are more inconveniences such as the amount of water in the streetcar than the phosphor (as a result, precipitation tends to occur before freezing, storage, transportation, thawing, etc. become a huge burden, and furthermore, the preparation of the phosphor slurry after thawing becomes complicated). (The problem mentioned above is that if long-distance transportation is not required, the water and phosphor may be mixed at a weight ratio of 3:1 by using appropriate surfactants, etc.).
(can be effectively put into practical use within the range of 1:100),
On the other hand, below the lower limit, there is a risk that the phosphor particles will aggregate before freezing. From these points, preferably l:
It is best to adjust it within the range of 4 to I:50. Considering the dispersion stability before and after thawing, the water content is 15% by volume.
Hereinafter, it is preferable to adjust the amount to 10% by weight or less.

It is preferable to add a surfactant to the frozen phosphor slurry to ensure the dispersion stability of the phosphor. Any of anionic, nonionic, and cationic surfactants can be used, and can be appropriately selected depending on the binder added during coating. Specifically, sodium naphthalene sulfonate, sodium lignin sulfonate, and sodium riboflavin phosphate can be used. The appropriate amount of surfactant to be added is 1 to 2.0% by weight, preferably 0.05 to 1.0% by weight of Q, OO based on the fluorescent weight Fd. By adding this surfactant, slurry preservation before and after freezing, a
; iIIM becomes extremely easy and is also very effective for producing fluorescent films.

Furthermore, the phosphor used in the present invention may be subjected to surface treatment as necessary before freezing.

As the surface treatment agent used here, for example, ]s
A1% 71% Inorganic compounds such as Zn and Zr, and organic compounds such as gelatin can be mentioned, but silica compounds, hydroxides of lead, and oxides of zinc are particularly recommended (Japanese Patent Publication No. 60-21675 No., Special Publication No. 61-465
No. 12, Japanese Patent Application No. 63-330648).

Furthermore, a binder or the like that is normally added at the time of coating may be added to this phosphor slurry before freezing.

In the present invention, by obtaining a phosphor coating slurry without drying after phosphor synthesis, water washing, etc., remarkable effects as described above can be achieved. A frozen mass obtained by freezing a phosphor slurry obtained by adding water without an aggregation period after washing and drying is also included in the present invention. This is because these frozen blocks also have superior dispersion stability and can yield a good fluorescent film compared to the conventional method of storing and transporting them in powder form.

Although the present invention is effective for any type of phosphor, its effect is particularly remarkable for color television phosphors that require the production of fine phosphor films. Examples of this type of phosphor include sulfide-based phosphors that use at least one of silver, copper, gold, etc. as the L activator, and phosphors that use at least one of europium, terbium, etc. as the main activator. Examples include acid sulfide-based or rare aluminate-based phosphors.

The phosphor slurry frozen mass of the present invention is prepared by firing the phosphor, washing it with water, adjusting the slurry concentration, adding an interfacial viscosity agent, etc. as necessary, and then cooling and freezing. The frozen mass is
The phosphor slurry may be frozen and then placed in a container, or the phosphor slurry placed in a container may be frozen. The container used here is preferably made of a material with low moisture permeability or a material with no moisture permeability. In containers with high moisture permeability, such as paper bags, the weight ratio of phosphor to water changes due to freeze-drying, making it necessary to adjust the slurry concentration after thawing. Furthermore, conventional powdered phosphors must be stored in full-scale containers such as cans and kept dry. However, since the frozen mass of the present invention retains its shape, it can be frozen in a simple container such as an organic resin film, transported to the container by a refrigerator truck, and stored in a freezer. You can also.

(Example 1) Zinc sulfide (ZnS) 200g, copper nitrate [Cu(110
-)t311.0] 1.52 g, aluminum acetate fA1. o(CIl,C00)4・411yO]2.
8g, bismuth iodide (BiI3) 0.2g.

After filling an alumina crucible with 2.0 g of sulfur'F+ (S), it was placed in an electric furnace and heated for 1 hour in an atmosphere of carbon-containing compound vapor.
It was fired for 2 hours at a temperature of 0.000°C. The fired product is crushed, washed with water, and classified, and the resulting phosphor slurry is mixed with water and phosphor (Zn).
After adjusting the weight ratio of S:Cu, AI) to 1:9, a 10% surfactant solution (Daiichi Kogyo Seiyaku, Tveen-20
) was added to the phosphor in an amount of 0.1% by weight, placed in a polyethylene container, and frozen in a freezer to obtain a frozen mass of phosphor slurry.

This frozen mass was stored in a freezer for 10 days, then thawed naturally, and water, polyvinyl alcohol, and In ammonium chromate were added to obtain a phosphor coating slurry. This phosphor and cloth slurry is extremely easy to adjust compared to conventional slurries, and pinholes and uneven coating were significantly reduced in coating tests.

(Example 2) Yttrium oxide (Y, O,) 109.75 g, terbium oxide (Tb, 0?) 4.673 g, dysprosium oxide (DV*0s) 0.56 g, sulfur (S) 60 g
, 40 g of sodium carbonate (NafCOs), and IO g of potassium phosphate (KffiPO4-3H,0) were thoroughly mixed, filled into an alumina crucible, and fired at 1200° C. for 2 hours. Thereafter, the mixture was washed with water, dispersed, and classified to obtain a phosphor slurry.

The median particle size of the phosphor in the slurry was measured using a Coulter counter and was found to be 4.0 uvr. On the other hand, water and phosphors (Y, O, S: Tb, D
The weight ratio with r) was adjusted to 1:]0, and then Example 1
A phosphor slurry frozen mass was prepared in the same manner as described above. This frozen mass was left to stand for 100 days, then thawed and the average particle diameter of the phosphor was measured again, and there was no change at all from that before freezing.

(Example 3) 2000 g of zinc sulfide (ZnS), silver nitrate (AgNO-
)0.32g, gallium nitrate [Ga(No-)s・8■
, 0 1.15g.

10 g of sodium chloride (Mail) and log of magnesium chloride (MgClt) were thoroughly mixed, filled in a quartz crucible, and fired at 950° C. for 3 hours. Thereafter, a phosphor slurry was prepared by washing with water, dispersing, and classifying. Add 30 ml of sodium citrate solution to this phosphor slurry and stir well, then add 40 @ 1 of 10% zinc sulfate solution, stir well again, suspend, and gradually add 2% sodium hydroxide solution. was added to adjust PIIJI to 5, and a surface treatment substance containing zinc ions and polycarboxylic acid ions was attached to the surface of the phosphor. This phosphor slurry contains water and phosphor (ZnS:Ag, Ga.

After adjusting the small amount ratio of CI) to 1:15, the mixture was placed in a polyethylene terephthalate container and frozen in a freezer to obtain a frozen phosphor slurry mass.

After storing this frozen mass for one month, it was thawed in a microwave oven, a phosphor coating slurry was prepared in the same manner as in Example], and a coating test was conducted. It was found that the adjustment was extremely easy compared to the conventional one. It was possible to obtain a good fluorescent film with few pinholes and coating unevenness.

(Example 4) The synthesized Y*OtS:14u phosphor was washed with water, dispersed,
After classification, the surface was treated with silica and zinc hydroxide, and immediately after drying, water was added to prepare a phosphor slurry with a ratio of water to phosphor of 1:4, which had the same surface activity as in Example 1. After adding the agent, the mixture was frozen to obtain a frozen phosphor slurry mass.

After storing this frozen mass for 100 days, it was broken down into small pieces using a crane jar, and after natural thawing for 24 hours, a phosphor or cloth slurry was prepared and a coating test was performed. This process was extremely easy, and a good fluorescent film with few pinholes and uneven coating could be obtained.

(Effects of the Invention) By adopting the configuration described above, the present invention is freed from the complexity of handling the conventional powdered phosphor, and freezes the phosphor as it is in a particle size suitable for coating. fixed inside,
At the time of use, a phosphor slurry of a predetermined slurry e[f in which the particles are uniformly dispersed can be obtained by simply thawing it in a container, and in the meantime, it can be stored and stored in a simple container. Now it can be transported. In addition, the drying process in the phosphor manufacturing process and/or the slurry preparation process for dispersing the powdered phosphor in water for coating) is no longer necessary, making it possible to significantly simplify the process. .

Claims (3)

[Claims] (1) The weight ratio of water and phosphor is 1:1 to 1:100.
A frozen lump of phosphor slurry, which is obtained by freezing a phosphor slurry adjusted to (2) The frozen mass of the phosphor slurry according to claim 1, wherein the phosphor slurry contains a surfactant. (3) A frozen lump of a phosphor slurry, which is characterized in that after preparing the phosphor slurry according to claim (1) or (2), the phosphor slurry is placed in a small moisture-permeable or non-moisture-permeable container and cooled and frozen. manufacturing method.