JP2753042B2 - Phosphor and processing method thereof - Google Patents

Description

The present invention relates to a phosphor used in a color cathode ray tube and a method for treating the phosphor.

(Prior Art) A method of forming a fluorescent film of a color cathode-ray tube generally involves preparing a phosphor slurry in which a phosphor is dispersed in an aqueous solution containing polyvinyl alcohol (PVA), ammonium bichromate and a surfactant, and then preparing the slurry. It is applied to a glass panel to form a fluorescent film. Thereafter, ultraviolet rays are irradiated through a shadow mask to cure the PVA in the irradiated portion, and then the fluorescent film other than the portion cured by development is removed to form phosphor stripes or dots.

The conditions required for the phosphor in this coating method are as follows: (1) A dense stripe or dot phosphor film is formed.

(2) No color mixing occurs.

(3) The attachment to the panel is good.

(4) In the pigment-attached phosphor, there is no pigment peeling in the slurry solution.

(5) A sufficient fluorescent film thickness is obtained (improving the sedimentation of the phosphor in the slurry solution).

And the like.

In recent years, since a color television having a high-quality phosphor film has been demanded, a more excellent phosphor satisfying the above conditions has been desired.

In order to satisfy these characteristics required at present, various improvements and developments have been made on the surface treatment of the phosphor.

For example, JP-A-54-102299, JP-B-59-8310,
A treatment method is disclosed in which a pigment-attached phosphor is brought into contact with a water-soluble organic compound solution to improve dispersibility.

Also, JP-B 60-21675, JP-B 61-46512, JP-B
62-39186 discloses a method of improving the dispersibility of a phosphor by attaching an inorganic compound to the phosphor surface.

(Problems to be Solved by the Invention) As described above, the dispersibility of the phosphor is improved to some extent by treating the phosphor with an inorganic compound or an organic compound.

However, it is still not enough given the high demands of the market. In particular, since the red fluorescent film is generally formed as a third color (applied in the order of green, blue, and red), the green and blue fluorescent films are applied on the previously formed panel surface having large irregularities. In order to form a dense and sufficiently thick fluorescent film, it is necessary that the phosphor has good dispersibility in a slurry solution and that there is no pigment peeling.

Furthermore, recently, since the production index has been accelerated to improve the work efficiency in the production of color cathode ray tubes, and a high-quality phosphor film has been required, a slurry solution of the phosphor has been applied onto the panel, and the It is necessary that the sedimentation speed of the phosphor is high to some extent, and that the formation of the fluorescent film on the panel is performed quickly.

However, in the above-described method, the sedimentation speed is not considered, and there is a problem that it takes time until the fluorescent film is formed.

In other words, the dispersibility of particles in a liquid is related to the sedimentation velocity, and particles with good dispersibility often show a low sedimentation velocity.

This is because the dispersibility of the particles is related to the force between the particles,
Particles having good dispersibility in a solution have a low force between the particles and have a good slip between the particles. Then, the particles are slid together to form a dense packing, so that the sedimentation volume value becomes small.

On the other hand, good dispersibility of particles generally means that sedimentation is difficult, and the sedimentation speed is low.

In order to increase the sedimentation speed, it is only necessary to strengthen the bonding between particles, but this causes slippage between particles, so that the sedimentation volume value increases, and sparse packing causes deterioration in the quality of the phosphor film. There was a problem.

The present invention has been made to address such a problem, there is no pigment peeling of the phosphor in the slurry solution,
Another object of the present invention is to provide a phosphor having both high dispersibility and a high sedimentation velocity, and a method for treating the phosphor.

[Constitution of the Invention] (Means for Solving the Problems) In the phosphor of the present invention, the surface of the phosphor is made of silicon dioxide,
At least one inorganic compound selected from the group consisting of zinc silicate, zinc hydroxide, aluminum silicate, zinc oxide, aluminum oxide, aluminum hydroxide, zinc sulfide, and zinc borate, and a copolymer of acrylic acid and methacrylic acid It is characterized by being coated with.

Further, the phosphor treatment method of the present invention, the phosphor surface,
Treated with at least one inorganic compound selected from the group consisting of silicon dioxide, zinc silicate, zinc hydroxide, aluminum silicate, zinc oxide, aluminum oxide, aluminum hydroxide, zinc sulfide, and zinc borate, and acrylic acid It is characterized in that a copolymer with methacrylic acid is coated at 0.001 to 0.3% by weight based on the phosphor and dried.

The phosphor of the present invention is coated with a copolymer of a specific inorganic compound, acrylic acid and methacrylic acid.

As the inorganic compound, zinc silicate, zinc hydroxide,
Preferred are silicon dioxide, zinc oxide, aluminum oxide, aluminum hydroxide, aluminum silicate, zinc sulfide, zinc borate and the like, and these can be used alone or as a mixture of two or more.

The coating amount of the inorganic compound varies depending on the inorganic compound used, but is usually 0.001% by weight to 0.8% by weight, preferably 0.01% by weight to 0.5% by weight.

If the coating amount of the inorganic compound is less than 0.001% by weight, the effect of the present invention cannot be obtained. This is not preferable because defects such as a phenomenon that a phosphor applied later is attached to the dot phosphor screen are likely to occur.

The copolymer of acrylic acid and methacrylic acid may be of various types having different molecular weights, but in the present invention, those having a molecular weight of 800,000 or less are preferred.

This is because those having a molecular weight of 800,000 or more have extremely high viscosity and are difficult to handle, and the phosphor obtained after coating becomes hard and has poor dispersibility in a slurry.

In addition, as long as it is a commercially available product, a copolymer of acrylic acid and methacrylic acid having a small molecular weight can also be used.

Further, the monomer ratio of the copolymer of acrylic acid and methacrylic acid in the present invention can be used as long as acrylic acid: methacrylic acid = 9: 1 to 2: 8, and acrylic acid: methacrylic acid is preferable. Acid = about 7: 3.

The coating amount of such a copolymer of acrylic acid and methacrylic acid is preferably 0.001% by weight to 0.3% by weight, more preferably 0.01% by weight to 0.1% by weight, based on the phosphor.

The coating amount of the copolymer of acrylic acid and methacrylic acid is 0.
If the amount is less than 001% by weight, the effect of the present invention cannot be obtained. On the other hand, if it exceeds 0.3% by weight, the phosphor becomes a hard lump in the drying step after coating, and it becomes difficult to finish the powder,
Further, since the pH of the phosphor is very acidic, phosphor slurries using the phosphor in this state undesirably lower the exposure sensitivity.

Further, the phosphor treatment method of the present invention, after coating the surface of the phosphor with the inorganic compound described above, further, a copolymer of acrylic acid and methacrylic acid, 0.00 with respect to the phosphor
It is characterized by being coated at 1 to 0.3% by weight and dried.

For example, when a blue light emitting phosphor is used, such a phosphor treatment is performed by a method described below.

The ZnS / Ag, Cl or pigment-adhered ZnS / Ag, Cl phosphor is put in pure water and sufficiently stirred.

Next, a fixed amount of a water glass solution is added to the stirring liquid, and the mixture is stirred.

Thereafter, in a solution containing the water glass and colloidal silica, any one of zinc sulfate, zinc chloride, zinc nitrate, etc. is added.
Two aqueous solutions are added, and the surface of the phosphor is coated with zinc silicate and silicon dioxide by a reaction between water glass and zinc.

Then, the phosphor is washed several times with pure water to remove residual ions, and then a fixed amount of a copolymer of acrylic acid and methacrylic acid is added, followed by stirring well.

This is filtered to make a cake and dried at a temperature of 100 to 200 ° C.

If the drying temperature is lower than 100 ° C., it takes a long time to dry sufficiently. On the other hand, if the temperature is higher than 200 ° C., the copolymer of acrylic acid and methacrylic acid deteriorates, which is not preferable. A more preferred temperature is between 120C and 160C.

By sieving the massive phosphor obtained after drying through a sieve, the phosphor subjected to the treatment of the present invention can be obtained.

Note that the above-described treatment method is an example of the present invention, and is not limited to the above-described zinc silicate and silicon dioxide surface treatment, but includes zinc hydroxide, zinc oxide, silicon dioxide, sulfide Phosphors whose surfaces are coated with at least one inorganic compound of zinc, zinc borate, aluminum hydroxide, aluminum oxide, and aluminum silicate are similarly treated with a copolymer of acrylic acid and methacrylic acid. The effect of can be obtained.

Further, the phosphor to which the processing method as described above is applied,
There is no particular limitation on a blue light emitting phosphor, a green light emitting phosphor, a red light emitting phosphor, and various phosphors can be used.

Blue light-emitting phosphors include ZnS / Ag, Cl, ZnS / Ag, Al, cobalt aluminate pigment coated ZnS / Ag, Cl, and ultramarine pigment coated Z
nS / Ag, Cl, ultramarine pigment-coated ZnS / Ag, Al, etc. are exemplified, and green light-emitting phosphors include ZnS / Cu, Au, Al, ZnS / Cu, Al, (Z
n, Cd) S / Cu, Al and the like.

Further, as red light emitting phosphors, Y ₂ O ₂ S / Eu, Y ₂ O ₃ / E
u, YVO ₄ / Eu, Bengala pigment-coated Y ₂ O ₂ S / Eu, and the like.

(Action) In the present invention, the surface of the phosphor is coated with a selected inorganic compound and further a copolymer of acrylic acid and methacrylic acid.

By such a coating treatment, in the pigment-coated phosphor, pigment peeling is reduced, and further, both the dispersibility of the phosphor in a slurry solution and the sedimentation speed are improved.

Therefore, a fluorescent film is quickly formed on the panel surface, and a dense and high-quality fluorescent film having a sufficient film thickness can be obtained.

(Example) Hereinafter, an example of the present invention will be described.

Example 1 First, 1 kg of a Y ₂ O ₂ S / Eu phosphor is dispersed in 8 l of pure water. 3.3 cc of water glass (containing 25% of Si) is added to the dispersion and stirred for 20 minutes, and then 0.4 mol / l of zinc sulfate (ZnSO ₄ )
After adding 33 cc of the solution, the mixture was stirred for 30 minutes.

After stirring, the phosphor is allowed to settle, and the supernatant is removed by decantation. Next, the phosphor was washed three times with 10 l of pure water, and then 200 cc of a 5% solution of a copolymer of acrylic acid and methacrylic acid having a molecular weight of 4000 was added, and pure water was added until the total amount became 1 for 60 minutes. Stirred. This was directly filtered by suction to obtain a phosphor particle dispersion in a cake state, and then dried at 150 ° C.

After drying, it is sieved with a 400 mesh sieve to obtain Y ₂ O ₂ S / E
u The surface of the phosphor is coated with 0.022% by weight of zinc silicate,
A phosphor coated with about 0.1% by weight of a copolymer of acrylic acid and methacrylic acid was obtained.

The dispersibility of the obtained phosphor in a slurry solution was measured.

The above-mentioned dispersibility is a value indicated by the sedimentation volume. A phosphor slurry is prepared by a usual method, and a certain amount thereof is put into a sedimentation tube.
The volume of the sedimented phosphor after 20 hours was read. The larger the value of the sedimentation volume (cc), the lower the dispersibility.

Further, the phosphor slurry thus obtained was applied on a cathode ray tube panel by a usual slurry method to form a phosphor film.

The formed fluorescent film had a high density and a sufficient film thickness, and the luminous luminance was measured. As a result, a luminous luminance higher than that of the fluorescent film not treated with the phosphor of the present invention was obtained.

The same effect as above was obtained even when the drying temperature was changed from 100 ° C to 200 ° C.

 Table 1 shows the results.

Furthermore, using the phosphor obtained by the treatment method of the present invention, a phosphor treated only with a copolymer of acrylic acid and methacrylic acid, and a phosphor treated only with zinc silicate, respectively, Was prepared, and a certain amount of the slurry solution was withdrawn into a sedimentation tube, and the sedimentation speed was examined.

The result is shown in FIG. The solid line is a phosphor whose surface is coated with a zinc silicate and a copolymer of acrylic acid and methacrylic acid according to the treatment method of the present invention, and the two-dotted oblique lines are treated only with a copolymer of acrylic acid and methacrylic acid. The dotted line shows the phosphor treated with only zinc silicate.

The horizontal axis shows the sedimentation time, and the vertical axis shows the value of the scale of the sedimentation tube, from which the position of the sedimentation interface was read.

As is clear from the figure, in the phosphor of the present invention shown by the solid line, the sedimentation interface descended faster than other phosphors, and the sedimentation speed was improved.

Example 2 First, 1 kg of ZnS / Ag, Cl phosphor was dispersed in 8 l of pure water. To this dispersion was added 3 cc of water glass (containing 25% of Si), and then 10 cc of a 10% colloidal silica solution, followed by stirring for 20 minutes. Then, 0.4 mol / l zinc sulfate (ZnSO ₄ ) solution 30
Add cc and stir for 30 minutes, after stirring, sediment the phosphor,
The supernatant was removed by decantation.

Next, the phosphor was washed three times with 10 l of pure water, and then had a molecular weight of 72.
5% of a copolymer of acrylic acid and methacrylic acid of 000
Add 20 cc of the solution and add pure water until the total volume is 1.
Stirred for 60 minutes.

This was directly filtered by suction to obtain a phosphor particle dispersion in a cake state, and then dried at 180 ° C. After drying, the surface of the ZnS / Ag, Cl phosphor was sieved with a 400 mesh
A phosphor was obtained, which was coated with SiO ₂ by weight% and zinc silicate by 0.02 weight%, and further coated with a copolymer of acrylic acid and methacrylic acid by 0.01 weight%.

The dispersibility of the phosphor obtained by the above treatment in the slurry solution was measured.

Further, this slurry was applied on a cathode ray tube panel by a usual slurry method, and the emission luminance of the formed fluorescent film was examined.

Table 1 shows the results. The drying temperature should be 100
The same effect as above was obtained even when the temperature was changed up to 200 ° C.

Example 3 1 kg of ZnS / Cu, Al phosphor was dispersed in 8 l of pure water. To this dispersion, 100 cc of a 1% ZnO dispersion was added and stirred for 20 minutes.
Next, 50 cc of a 0.4 mol / l zinc sulfate (ZnSO ₄ ) solution was added, followed by stirring for 20 minutes.

After stirring, the phosphor was allowed to settle, and the supernatant was removed by decantation. Next, the phosphor was washed three times with 10 l of pure water, 100 cc of a 5% solution of a copolymer of acrylic acid and methacrylic acid having a molecular weight of 28,000 was added, and pure water was added until the total amount became 1. Stirred for minutes.

This was directly filtered by suction to obtain a phosphor particle dispersion in a cake state, and then dried at 160 ° C. After drying, by sieving with a 400 mesh sieve, the surface of the ZnS / Cu
Coated with 0.1% by weight zinc oxide and 0.12% by weight zinc hydroxide,
Further, a phosphor coated with 0.05% by weight of a copolymer of acrylic acid and methacrylic acid was obtained.

The dispersibility of the phosphor obtained by the above treatment in the slurry solution was measured.

Further, this slurry was applied on a cathode ray tube panel by a usual slurry method, and the emission luminance of the formed fluorescent film was examined.

Table 1 shows the results. The drying temperature should be 100
The same effect as above was obtained even when the temperature was changed up to 200 ° C.

Example 4 1 kg of ZnS / Cu, Au, Al phosphor was dispersed in 8 l of pure water.
To this dispersion, 1.5 cc of 25% water glass, 10 cc of 10% colloidal silica solution, and 3 cc of 50% Al ₂ (SO ₄ ) ₃ solution were sequentially added, followed by stirring for 20 minutes.

 Then, the mixture was adjusted to pH 5.8 with a 10% KOH solution and stirred for 30 minutes.

After stirring, the phosphor was allowed to settle, and the supernatant was removed by decantation. Next, the phosphor was washed three times with 10 liters of pure water, and then 40 cc of a 5% solution of a copolymer of acrylic acid and methacrylic acid having a molecular weight of 200,000 was added, and pure water was added until the total amount became 1. Stirred for 60 minutes.

This was directly filtered by suction to obtain a phosphor particle dispersion in a cake state, and then dried at 150 ° C. After drying, the surface of the ZnS / Cu, Au, Al phosphor was reduced to 0.
A phosphor coated with 1% by weight of silicon dioxide and 0.08% by weight of aluminum silicate and further coated with a copolymer of acrylic acid and methacrylic acid of 0.02% by weight was obtained.

The dispersibility of the phosphor obtained by the above treatment in the slurry solution was measured.

Further, this slurry was applied on a cathode ray tube panel by a usual slurry method, and the emission luminance of the formed fluorescent film was examined.

 Table 1 shows the results.

The same effect as above was obtained even when the drying temperature was changed from 100 to 200 ° C.

Example 5 1 kg of ultramarine blue pigment-coated ZnS / Ag, Cl phosphor using gelatin and gum arabic resin as an adhesive was dispersed in 8 l of pure water. 25 cc of 11% sodium tetraborate (Na ₂ B ₄ O ₇ ) solution
Was added and stirred for 30 minutes.

Then, 20 cc of a 0.4 mol / l zinc sulfate (ZnSO ₄ ) solution was added, and the mixture was stirred for 30 minutes.

After stirring, the phosphor was allowed to settle, and the supernatant was removed by decantation. Next, the phosphor was washed three times with 10 liters of pure water, and then 10 cc of a 5% solution of a copolymer of acrylic acid and methacrylic acid having a molecular weight of 15,000 was added, and pure water was added until the total amount became 1. Stirred for 60 minutes.

This was directly filtered by suction to obtain a phosphor particle dispersion in a cake state, and then dried at 100 ° C. After drying, the surface of the ultramarine blue pigment-coated ZnS / Ag, Cl phosphor is coated with 0.09% by weight of zinc borate by sieving with a 400 mesh sieve, and a copolymer of 0.005% by weight of acrylic acid and methacrylic acid is obtained. Was obtained.

The dispersibility of the phosphor obtained by the above treatment in the slurry solution was measured.

Further, this slurry was applied on a cathode ray tube panel by a usual slurry method, and the emission luminance of the formed fluorescent film was examined.

 Table 1 shows the results.

In this example, since gelatin and gum arabic resin are used, if the drying temperature is set to 100 ° C. or higher, the quality of the resin deteriorates, which is not preferable.

Example 6 Cobalt blue pigment-coated ZnS / Ag and Cl phosphors (1 kg) using an acrylic emulsion resin as an adhesive were dispersed in 8 l of pure water. To this dispersion was added 5 cc of 25% water glass and stirred well, then 10 cc of 10% Al ₂ O ₃ dispersion and 0.4 mol / l Zn
Successively added and SO ₄ solution 50 cc, and stirred for 30 minutes.

After stirring, the phosphor was allowed to settle, and the supernatant was removed by decantation.

Next, the phosphor was washed three times with 10 l of pure water, and then the molecular weight was 2
5% of 8,000 acrylic acid and methacrylic acid copolymer
Add 60 cc of the solution and add pure water until the total amount is 1.
Stirred for 60 minutes. This was directly subjected to suction filtration to obtain a phosphor particle dispersion in a cake state, and then dried at 150 ° C.

After drying, the surface of the cobalt blue pigment-coated ZnS / Ag, Cl phosphor is 0.1% by weight by sieving with a 400 mesh sieve.
A phosphor was obtained which was coated with aluminum oxide (Al ₂ O ₃ ) and 0.03% by weight of zinc silicate, and further coated with 0.03% by weight of a copolymer of acrylic acid and methacrylic acid.

The dispersibility of the phosphor obtained by the above treatment in a slurry solution and the pigment release rate were measured.

The pigment removal rate indicates the pigment removal rate of the pigment-attached phosphor in the slurry after stirring the ordinary phosphor slurry for 7 days.

Further, this slurry was applied on a cathode ray tube panel by a usual slurry method, and the emission luminance of the formed fluorescent film was examined.

Table 1 shows the results. The drying temperature should be 100
The same effect as above was obtained even when the temperature was changed up to 200 ° C.

Dispersed red iron oxide pigment coated Y ₂ O ₂ S / Eu phosphor 1kg was the adhesive Example 7 Acrylic emulsion resin in pure water 8l. 25 cc of a 10% Al (NO ₃ ) ₃ solution was added to the dispersion, the pH was adjusted to 8.5 with dilute aqueous ammonia, and the mixture was stirred for 30 minutes.

After stirring, the phosphor was allowed to settle, and the supernatant was removed by decantation. Next, the phosphor was washed three times with 10 l of pure water, and then 600 cc of a 5% solution of a copolymer of acrylic acid and methacrylic acid having a molecular weight of 3000 was added, and pure water was added until the total amount became 1. Stirred for 60 minutes.

This was directly filtered by suction to obtain a phosphor particle dispersion in a cake state, and then dried at 150 ° C.

After drying, the surface of the bengara-coated Y ₂ O ₂ S / Eu phosphor is coated with 0.05% by weight of aluminum hydroxide by sieving through a 400 mesh sieve, and 0.03% by weight of acrylic acid and methacrylic acid A phosphor coated with a polymer was obtained.

The dispersibility of the phosphor obtained by the above treatment in a slurry solution and the pigment release rate were measured.

Further, this slurry was applied on a cathode ray tube panel by a usual slurry method, and the emission luminance of the formed fluorescent film was examined.

 Table 1 shows the results.

The same effect as above was obtained even when the drying temperature was changed from 100 to 200 ° C.

Example 8 1 kg of a Y ₂ O ₂ S / Eu phosphor was dispersed in 8 l of pure water. next
20 cc of a 0.4 mol / l zinc sulfate (ZnSO ₄ ) solution was added, followed by thorough stirring.

Further, 4 cc of ammonium polysulfide solution (commercially available) was added, and the mixture was stirred for 30 minutes.

After stirring, the phosphor was allowed to settle, and the supernatant was removed by decantation. Next, the phosphor was washed three times with 10 l of pure water, and then 50 cc of a 5% solution of a copolymer of acrylic acid and methacrylic acid having a molecular weight of 21,000 was added, and pure water was added until the total amount became 1 for 60 minutes. Stirred. This was directly subjected to suction filtration to obtain a phosphor particle dispersion in a cake state, and then dried at 150 ° C.

After drying, it is sieved with a 400 mesh sieve to obtain Y ₂ O ₂ S / E
u The phosphor surface is coated with 0.06% by weight zinc sulfide,
A phosphor coated with 25% by weight of a copolymer of acrylic acid and methacrylic acid was obtained.

The dispersibility of the obtained phosphor in a slurry solution was measured.

Further, this slurry was applied on a cathode ray tube panel by a usual slurry method, and the emission luminance of the formed fluorescent film was examined. Table 1 shows the results.

The same effect as above was obtained even when the drying temperature was changed from 100 to 200 ° C.

In Table 1, the emission luminance is a value obtained by comparing the phosphors used in the examples with the phosphors not subjected to the treatment according to the present invention.

In addition, dispersibility and pigment peeling, the results of each example,
The results of the comparative examples in which the treatment according to the present invention was not performed for each example are shown side by side.

As is clear from the above results, in the present invention, by combining the selected inorganic compound and the copolymer of acrylic acid and methacrylic acid at a coating amount within the above range, it is obtained by the single treatment. The effect of the property improvement which was not obtained was obtained.

That is, the dispersibility of the phosphor in the slurry solution and the pigment adhesion were further improved, and the phosphor sedimentation rate in the phosphor slurry was improved.

In particular, due to the faster phosphor sedimentation rate in the slurry solution, when forming the phosphor film by applying the slurry on the panel, a high-quality phosphor with high density A film could be formed in a short time.

[Effects of the Invention] The phosphor of the present invention has a surface coated with a selected inorganic compound and a copolymer of acrylic acid and methacrylic acid.

Therefore, the dispersibility of the phosphor in the slurry solution and the pigment adhesion can be improved, and the phosphor sedimentation rate in the slurry solution can be improved.

[Brief description of the drawings]

FIG. 1 is a graph comparing the sedimentation speed of a phosphor in a slurry solution using a Y ₂ O ₂ S / Eu phosphor. The horizontal axis indicates the sedimentation time, and the vertical axis indicates the position of the sedimentation interface. The solid line is a phosphor whose surface is coated with a zinc silicate and a copolymer of acrylic acid and methacrylic acid according to the treatment method of the present invention, and the two-dotted oblique lines are treated only with a copolymer of acrylic acid and methacrylic acid. And the dotted line represents the phosphor treated only with zinc silicate.

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Hiroyasu Yajima 72 Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba Electronic Device Engineering Co., Ltd. (56) References JP-A-57-149381 (JP, A) 2-178387 (JP, A)

Claims (2)

(57) [Claims] The surface of the phosphor is at least one selected from the group consisting of silicon dioxide, zinc silicate, zinc hydroxide, aluminum silicate, zinc oxide, aluminum oxide, aluminum hydroxide, zinc sulfide, and zinc borate. A phosphor characterized by being coated with a kind of inorganic compound and a copolymer of acrylic acid and methacrylic acid. 2. The method of claim 1, wherein the surface of the phosphor is at least one selected from the group consisting of silicon dioxide, zinc silicate, zinc hydroxide, aluminum silicate, zinc oxide, aluminum oxide, aluminum hydroxide, zinc sulfide, and zinc borate. A method for treating a phosphor, characterized in that the phosphor is coated with a copolymer of acrylic acid and methacrylic acid in an amount of 0.001 to 0.3% by weight and dried.