JPH04214789A - Fluorescent material for cathode ray tube and surface treatment - Google Patents

Abstract

PURPOSE:To provide the subject material having sharp dots and stripes, having good adhesive characteristics and having little haze. CONSTITUTION:A compound containing indium, zirconium or antimony is adhered to the surfaces of fluorescent material particles through SiO2. The SiO2 can be strongly adhered to the surfaces of the particles, and the particles can have excellent dispersibility and strong adhesivity and can form excellent fluorescent surface hardly having haze.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor for cathode ray tubes that has excellent coating properties on cathode ray tubes and a method for surface treatment thereof.

0002

2. Description of the Related Art The phosphor screen of a color cathode ray tube is formed into dots or stripes by applying a phosphor slurry to a face plate and using a photographic printing method. The phosphor slurry used is a phosphor slurry dispersed in a photosensitive resin solution containing ammonium dichromate, PVA (polyvinyl alcohol), and a surfactant.

The phosphor screen formed in this manner is mainly required to have the following characteristics. a. Forming dense dots or stripes with uniform film thickness. b. Sharp dots or stripes. In other words, each color of phosphor is applied so that all dots or stripes are applied at predetermined positions and in a predetermined shape and width. c Dots or stripes must not peel off from the faceplate. d No color mixing of phosphor particles. Applied in dots or stripes, the red, blue, and
The green phosphor particles do not overlap with the adjacent light-emitting component of a different color. In other words, there is no color mixture. e
No haze. That is, after forming the dots or stripes constituting the luminescent component, no excess portion that is washed away remains on the face plate.

The above characteristics are affected by the surface condition of the phosphor. For this reason, phosphors have been developed in which various surface treatment substances are attached to the phosphor.

SiO2 is the most easily used surface treatment material that adheres to the phosphor. The surface treatment substance is Si
A phosphor containing O2 is produced by adding a silicate compound to a phosphor suspension and adding an aqueous solution of Zn, Al, Mg, Ba, Ca, etc. to the phosphor suspension to produce a silicate compound.

Japanese Patent Publication No. 50-15747 discloses a method of surface treating a phosphor by adding potassium water glass and zinc sulfate to an aqueous suspension of the phosphor. In addition, the special public corporation Showa 6
Japanese Patent No. 1-46512 discloses a phosphor in which silica, a zinc compound, and an aluminum compound are attached to the phosphor.

[0007]

[Problems to be Solved by the Invention] The phosphors described in the above publications were still insufficient to satisfy all of the characteristics a to e above.

For example, when zinc silicate is attached to the phosphor, the dispersibility in the photosensitive resin solution improves, and the characteristics a, b, and c can be satisfied. However, the characteristics of d and e were not satisfactory because the phosphor particles were scattered to neighboring dots. Further, phosphors surface-treated with potassium water glass and zinc sulfate also have the drawback that they cannot fully satisfy all of the characteristics a to e.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a phosphor for cathode ray tubes that satisfies all of the above properties and has excellent coating properties, and a method for manufacturing the same.

0010

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted intensive research on surface treatment substances and surface treatment methods. As a result, by attaching SiO2 to a phosphor for a cathode ray tube via a compound containing indium, zirconium, or antimony, it was possible to satisfy all of the above characteristics.

That is, the surface treatment substance that is attached to the surface of the phosphor is prepared by adding an aqueous silicate solution or a solution containing colloidal silica and indium, zirconium, or antimony to an aqueous suspension containing the phosphor, and adjusting the pH. By surface treating the phosphor with this compound, we succeeded in obtaining a phosphor for cathode ray tubes with excellent coating properties.

[0012] In the surface treatment method for obtaining the phosphor of the present invention, the phosphor is treated in the following steps. ■ Adding an aqueous silicate solution or colloidal silica and a solution containing indium, zirconium or antimony to the aqueous suspension containing the phosphor. (2) An alkali or acid is added to the phosphor suspension to adjust the pH of the suspension to 4 to 10, and a surface treatment substance obtained from silica, etc. and indium, etc. added to the phosphor particles is adhered to the phosphor particles. ■ After that, wash the phosphor with water,
Separate and dry.

Furthermore, in the present invention, in addition to a silicate aqueous solution or a solution containing colloidal silica and indium, zirconium or antimony, a solution containing zinc and/or aluminum may also be added to the phosphor suspension. can.

The compounds attached to the surface of the phosphor of the present invention will now be explained. It has long been known that silica sol can be aggregated by adding an electrolyte such as zinc sulfate or aluminum sulfate to a solution containing silica sol and adjusting the pH. Taking aluminum as an example, this reaction is explained to be the result of three reaction steps (a), (b) and (c) below. (Inorganic Chemistry Complete Book Si,
P295, Maruzen).

(a) Generation of a flocculant by hydrolysis and polymerization of aluminum; (b) Destabilization of the sol by specific adsorption of isopolycations that reduce the surface potential of colloidal particles;
(c) collisions due to movement of colloidal particles due to Brownian motion or velocity gradients;

Similarly, in the present invention, taking indium as an example, when an aqueous solution containing colloidal silica and indium is added and the pH is adjusted, In(OH)3 is produced and the colloidal silica is aggregated to form phosphor particles. Adheres to surfaces. In this state, the compounds attached to the surface of the phosphor particles are SiO2.nH2O (n≧0) and I
n(OH)3, or a coprecipitate of silica and indium. When the phosphor is separated and dried, SiO2 and In(
OH)3, or SiO2 and In2O3・nH2O
(n≧0), or a mixed crystal of silica and indium hydrate is considered to be attached.

In any case, when a surface treatment substance is attached to a phosphor, it is not possible to identify the substance attached to the surface using a surface analysis device such as X-ray diffraction, so FIGS. 4. As a blank test, an aqueous indium chloride solution was added to a solution containing colloidal silica,
After adjusting the pH to 7.5 with aqueous ammonia and washing and separating the precipitate generated, the precipitate was incubated at 100°C for 3 hours for 10
The X-ray diffraction patterns of each precipitate when dried at 0°C for 12 hours, 150°C for 3 hours, and 200°C for 3 hours are shown in order.

As shown in FIGS. 1 to 4, when the precipitates were dried under the respective conditions, In(OH)3 peaks were detected in all cases. When the drying temperature was 200° C., unspecified peaks appeared in addition to the peaks of In2O3 and In(OH)3.

FIGS. 5 to 7 also show, as a blank test, a precipitate obtained by adding an aqueous solution of indium sulfate to a solution containing colloidal silica and adjusting the pH in the same manner at 100°C, 150°C, and 200°C. The figure shows the X-ray diffraction pattern of each precipitate after drying for 3 hours. In these figures, the peak of In(OH)3 is also marked with ●,
The In2O3 peak is indicated by a circle. When indium sulfate is used instead of indium chloride, the resulting compound becomes nearly amorphous, making it difficult to detect peaks, but when dried at 100°C and 150°C, peaks that appear to be indium hydroxide can be detected. .

FIGS. 8 to 10 also show, as a blank test, that antimony chloride (SbCl3) aqueous solution was added to a solution containing colloidal silica, and the pH was adjusted to 7.5 with aqueous ammonia. After washing the precipitate with water and separating it, it was heated at 100℃, 150℃, 20
The X-ray diffraction pattern of each precipitate when dried at 0° C. for 3 hours is shown.

Antimony (III) chloride is thought to be partially hydrolyzed in an aqueous solution to generate SbOCl, but when used as a flocculant for colloidal silica, SbOCl cannot be detected in these X-ray diffraction patterns. zu, Sb4O
A peak that appears to be 5Cl2 or Sb2O3 is detected.

FIGS. 11 to 13 show, as a blank test, a precipitate formed by adding a zirconium chloride (ZrCl4) aqueous solution to a solution containing colloidal silica and adjusting the pH to 7.5 with aqueous ammonia. After washing with water and separating, 100℃, 150℃, 20℃
The X-ray diffraction pattern of each precipitate when dried at 0° C. for 3 hours is shown.

[0023] In this case as well, the ZrO2 peak cannot be detected, and each precipitate is amorphous, making it impossible to specify what kind of compound the added zirconium is.

In the X-ray diffraction diagrams of the precipitates produced from the colloidal silica and the metal ions shown in FIGS. 1 to 13, some weak peaks appear, but it is clear that the added metal ions are Most of the silica is thought to be in the form of hydrates or basic salts, and since silica is amorphous, it is not possible to specify what kind of compound it exists in.

Substances attached to the surface of the phosphor particles of the present invention can be obtained by adding a silicate aqueous solution or colloidal silica and a solution containing indium, zirconium or antimony to a phosphor suspension. By adjusting the pH, SiO2 is attached to the surface of the phosphor particles via a compound containing indium, zirconium, or antimony.

The phosphors used in the present invention are generally known as phosphors for cathode ray tubes, and include zinc sulfide phosphors, zinc phosphate phosphors, zinc silicate phosphors, and yttrium oxysulfide. phosphors, yttrium oxide phosphors, indium borate phosphors, etc. can be used.

As the aqueous silicate solution added to the phosphor suspension, an aqueous silicate solution such as sodium silicate or potassium silicate can be used. Colloidal silica is also often used.

As the solution containing indium, for example, an aqueous solution of indium sulfate, indium chloride, indium nitrate, etc. can be used.

The antimony-containing solution may be, for example, an aqueous solution of antimony chloride, antimony sulfate, etc. There are trivalent and pentavalent antimony, and either of them may be used.

[0030] As the solution containing zirconium, an aqueous solution of zirconium chloride, zirconium sulfate, zirconium acetate, etc. can be used, and either of the trivalent and tetravalent zirconium types may be used.

[0031] The present invention may also be combined with the conventional method of depositing SiO2 using an aqueous solution containing zinc, aluminum, etc., and the aqueous solution contains zinc or aluminum sulfate or chloride as well as indium. , nitrate, etc. can be used.

The pH of the phosphor suspension can be adjusted by adding a solution containing indium, zirconium or antimony.
Adjust to a range of 4 to 10 so that O2 is attached to the surface of the phosphor particles. NaOH, KOH, NH4OH, etc. can be used as the alkali added for pH adjustment. CH3COOH, HCl, HNO3, H2SO4, etc. can be used as the acid.

The amount of the silicic acid-containing aqueous solution or colloidal silica added to the phosphor suspension is determined by the amount contained therein.
In terms of the amount of SiO2, it is usually 0.01 parts by weight or more and 3 parts by weight or less, preferably 0 parts by weight, per 100 parts by weight of the phosphor.
．． Adjust to a range of 0.05 parts by weight or more and 1.0 parts by weight or less.

The amount of indium, zirconium or antimony added to the phosphor suspension is determined by the amount contained in the aqueous solution.
The amount of these metals is usually adjusted to a range of 0.0005 parts by weight or more and 1.0 parts by weight or less, preferably 0.01 parts by weight or more and 0.5 parts by weight or less, per 100 parts by weight of the phosphor. .

[0035] Furthermore, when an aqueous solution containing zinc and/or aluminum is added to the phosphor suspension, the amount thereof is calculated in the same manner as 100 parts by weight of the phosphor.
Each content is adjusted to be more than 0 parts by weight and less than 0.1 parts by weight, preferably more than 0.001 parts by weight and less than 0.05 parts by weight.

The above range is adjusted when the amount of SiO2 is 3 parts by weight or more, the amount of indium etc. is 1 part by weight or more, or the amount of zinc and aluminum is each 0.1 part by weight or more or the total amount thereof is 3 parts by weight or more. This is because if the amount is 0.1 part by weight or more, the dispersibility of the obtained phosphor in the photosensitive resin solution becomes poor.

In the surface treatment method of the present invention, SiO2, indium, etc., zinc,
The optimum amount of aluminum to be added is 0.08 to 0.8 parts by weight of SiO2, 0.03 to 0.5 parts by weight of indium, etc., and 0.00 parts of zinc and aluminum to 100 parts by weight of the phosphor. The range is 0.01 or more and 0.05 parts by weight or less.

Furthermore, the surface treatment method of the present invention does not specify the drying conditions for the phosphor to which the surface treatment substance is attached. However, preferably, the drying temperature of the phosphor is preferably 8
Adjust to a range of 0°C to 200°C. This is because drying or baking at a temperature of 200° C. or higher tends to deteriorate the dispersibility of the phosphor.

[0039]

[Operation] FIG. 14 shows that 0.1 parts of colloidal silica is added to a phosphor suspension containing 100 parts by weight of ZnS:Ag,Al phosphor.
parts by weight, and further added indium sulfate aqueous solution in varying amounts to adjust the pH to 7.5,
0.1 weight of colloidal silica was added to a phosphor suspension containing the surface-treated phosphor of the present invention obtained by washing with water, separating and drying at 150°C for 3 hours, and 100 parts by weight of ZnS:Ag,Al phosphor. % and then added zinc sulfate aqueous solution in varying amounts to adjust the pH to 7.4,
FIG. 3 is a diagram showing a comparison of dispersibility with a conventional surface-treated phosphor obtained by washing with water, separating, and drying at 150° C. for 3 hours.

This figure shows that 7.5 g of phosphor with each surface treatment substance attached is treated with ammonium dichromate and PVA.
The phosphor is dispersed in 15 ml of a solution containing phosphor and a surfactant, placed in a centrifuge tube, and centrifuged at 1000 rpm for 15 minutes.The volume of sedimentation represents the dispersibility of the phosphor. A phosphor with excellent dispersibility has a slow sedimentation rate and a small sedimentation volume.

As is clear from this figure, the phosphor to which the indium-containing surface treatment substance is attached has a smaller settling volume and better dispersibility than the conventional phosphor to which the zinc-containing surface treatment substance is attached. has been improved.

Table 1 shows a comparison of the peeling rates of SiO2 attached to the surface of the surface-treated phosphor of the present invention and the conventional surface-treated phosphor. The peeling rate of SiO2 was measured as follows.

A coating slurry was formed by mixing a certain amount of phosphor into an ordinary coating solution containing dichromate, etc., and the coating slurry was refluxed for a certain period of time using a pump used in the actual cathode ray tube coating process. After that, separate the phosphor,
After washing with water three times, the SiO adhering to the phosphor dries.
The two amounts were analyzed, and the amount of SiO2 that was peeled off was measured from the amount of SiO2 that was initially attached. Note that ZnS: Cu, Au
The phosphor contains 0.3% by weight of SiO2, In, Sb, Zr,
Phosphors to which 0.05% by weight of Zn was attached were used.

[Table 1]

[0044] The present invention provides SiO
2 can be firmly attached to the surface of the phosphor. Therefore, peeling of SiO2 on the surface of the phosphor is reduced, and the dispersibility of the phosphor is improved, resulting in a phosphor for cathode ray tubes that is less likely to cause haze and has excellent adhesive strength. Further, even when conventional zinc and aluminum are used in combination, a phosphor exhibiting good coating properties can be obtained.

[0045]

【Example】

(Examples 1 to 13) Phosphors of the present invention were obtained through the following steps (1) to (2). (2) Suspend 200 g of phosphor for cathode ray tubes in 600 ml of ion-exchanged water to make a phosphor suspension. ■ Adding an aqueous solution containing colloidal silica, granular silica or silicic acid to the phosphor suspension. The SiO2 equivalent content of the silica added is shown in Tables 2 to 5. ■ Adding an aqueous solution containing indium, zirconium or antimony to the phosphor suspension. Tables 2 to 5 show the metal contents of the aqueous solutions of metal In, Sb, and Zr to be added and their amounts added. ■
While stirring the suspension, add the alkali or acid dropwise,
Adjust pH. After that, stirring is stopped and the mixture is left standing to allow the phosphor to settle. The type of acid or alkali to be added and the pH are shown in Tables 2 to 5. ■ Wait for the phosphor to settle down sufficiently, discard the supernatant, add water again, stir and let stand to settle the phosphor. After repeating this operation three times and washing with water, the phosphor is separated by suction filtration using a Nutsche filter lined with filter paper. ■ Take out the phosphor from Nutsche 8
Dry at 0°C to 200°C for 2 to 8 hours. (2) The dried phosphor is passed through a 380 mesh sieve to obtain the phosphor of the present invention, and then subjected to each test.

The conditions in the above examples are shown in Tables 2 to 5. In these tables, the type of phosphor for cathode ray tubes used is shown in (■), the concentration, type and amount of the aqueous solution containing silica is shown in (■), the concentration of the aqueous solution containing indium, etc.
The type and amount added are shown in (), the type of alkali or acid added dropwise, the pH of the suspension are shown in (), and the drying temperature and drying time are shown in ().

[0047]

[Table 2]

[0048]

[Table 3] *In the table, 2% In(NO3)3, 1% Z
n(SO4)2 means In content 2%, Zn content 2%
This is the meaning of

[0049]

[Table 4]

[0050]

[Table 5] [Comparative Examples 1 to 13] In the steps ① to ② of the example, the aqueous solution containing indium etc. in ① was replaced with an aqueous solution containing Zn or Al, and the rest was carried out in the same manner as in the example. A conventional surface-treated phosphor was obtained. These are shown in Tables 6 to 9.

[0051]

[Table 6]

[0052]

[Table 7]

[0053]

[Table 8]

[0054]

[Table 9]

(Comparison of coating properties between Examples and Comparative Examples) The phosphors obtained in Examples 1 to 13 and the corresponding Comparative Examples 1 to 13 were coated with ammonium dichromate, PVA, and a surfactant. After dispersing the sample in a photosensitive resin solution and applying it to a face plate, it was exposed to light using a striped shadow mask, and the coating characteristics were evaluated.

[Comparison of Sharpness in Coating Characteristics] Stripes formed of a phosphor with excellent dispersibility have straight parallel edges. Stripes formed of a phosphor with poor dispersibility have uneven edges, resulting in parallel wavy lines. Therefore, when taking the ratio of wavy line length/straight line distance, a sharp phosphor has a ratio close to 1.

[Comparison of Adhesive Strength of Phosphors] A phosphor slurry is applied to a face plate and dried. Thereafter, when a striped shadow mask is applied and exposed, a variable transmittance filter is installed between the exposure light source and the shadow mask. The stripe width of the phosphor screen formed when exposed with a filter with 100% transmittance is 18
The filter transmittance is set to 0 μm, and the exposure amount is decreased by gradually decreasing the filter transmittance. As the exposure amount decreases,
The width of the stripes on the phosphor screen becomes narrower, and stripes eventually peel off. Therefore, the stripe width was evaluated as the adhesive strength of the phosphor. In other words, it can be considered that the smaller the stripe width that begins to peel off, the stronger the adhesive force of the phosphor is.

[Comparison of haze] This characteristic is as follows: After exposure and cleaning, unit phosphor screen (1 mm2)
The number of phosphors remaining in areas other than the surrounding stripes was counted by microscopic observation, and the average of the three locations was taken, and 3 or less were judged as excellent, 4 or more as good, and 10 or more as poor. The above measurement results are shown in Tables 10 and 11.

[0059]

[Table 10]

[0060]

[Table 11]

[0061]

As described above, the phosphor for cathode ray tubes according to the present invention has Si on its surface due to the action of compounds such as indium, zirconium, or antimony attached to the phosphor.
O2 can be firmly attached, and in addition to dispersibility, it has excellent adhesive strength, and an excellent phosphor screen with almost no haze can be formed.

[0062]

[Brief explanation of the drawing]

[Figure 1] X-ray diffraction diagram of deposits on the surface of the phosphor of the present invention

[Figure 2] X of deposits on the surface of the phosphor of the present invention
line diffraction diagram

[Figure 3] X-ray diffraction diagram of deposits on the surface of the phosphor of the present invention

[Figure 4] X-ray diffraction diagram of deposits on the surface of the phosphor of the present invention

[Figure 5] X-ray diffraction diagram of deposits on the surface of the phosphor of the present invention

[Figure 6] X-ray diffraction diagram of deposits on the surface of the phosphor of the present invention

[Figure 7] X-ray diffraction diagram of deposits on the surface of the phosphor of the present invention

[Figure 8] X-ray diffraction diagram of deposits on the surface of the phosphor of the present invention

[Figure 9] X-ray diffraction diagram of deposits on the surface of the phosphor of the present invention

[Figure 10]
X-ray diffraction diagram of deposits on the surface of the phosphor of the present invention

[Figure 11]
X-ray diffraction diagram of deposits on the surface of the phosphor of the present invention

[Figure 12]
X-ray diffraction diagram of deposits on the surface of the phosphor of the present invention

[Figure 13
] X-ray diffraction diagram of deposits on the surface of the phosphor of the present invention

[Figure 1
4] A diagram showing a comparison of the dispersibility of the phosphor of the present invention and a conventional phosphor.

Claims (2)

[Claims] [Claim 1] SiO through a compound containing indium, zirconium or antimony on the surface of the phosphor particles.
A phosphor for a cathode ray tube, characterized in that: 2 is attached thereto. 2. Adding a silicate aqueous solution or colloidal silica and a metal-containing solution to a suspension containing a phosphor,
In a surface treatment method in which a surface treatment substance containing silica is attached to the surface of a phosphor by adjusting the pH of a suspension, the metal-containing solution is a solution containing any one of indium, zirconium, or antimony. A method for surface treatment of a phosphor, characterized by the following.