JP2906715B2 - Phosphor for cathode ray tube and surface treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor for a cathode ray tube having excellent coating properties on a cathode ray tube and a method for treating the surface of the phosphor.

[0002]

2. Description of the Related Art The phosphor screen of a color cathode ray tube is formed in a dot or stripe shape by applying a phosphor slurry to a face plate and using a photographic printing method. As the phosphor slurry, one obtained by dispersing the phosphor slurry in a photosensitive resin solution containing ammonium bichromate, PVA (polyvinyl alcohol) and a surfactant is used.

The phosphor screen thus formed is required mainly to have the following characteristics. a Forming dense dots or stripes with a uniform film thickness. b The dots or stripes must be sharp. That is, the phosphor of each color is applied, and all dots or stripes are applied at predetermined positions in a predetermined shape and width. c Dots or stripes do not come off the faceplate. d There is no mixing of phosphor particles. The red, blue, and green phosphor particles, which are applied in a dot or stripe shape and constitute each light emitting component, do not overlap with adjacent light emitting components of different colors. That is, there is no color mixing. e No haze. That is, after forming the dots or stripes that constitute the light emitting component, no surplus 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 in which a number of surface treatment substances are attached to phosphors have been developed.

There is SiO ₂ as a surface treatment substance which is most easily used after adhering to the phosphor. The surface treatment substance is SiO
_The phosphor containing ₂ is produced by adding a silicate compound to a phosphor suspension and adding an aqueous solution of Zn, Al, Mg, Ba, Ca, or the like to generate 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, Tokiko Sho 6
JP-A-46512 discloses a phosphor in which silica, a zinc compound and an aluminum compound are attached to the phosphor.

[0007]

The phosphors described in the above publications are still insufficient to satisfy all of the above characteristics a to e.

For example, when zinc silicate is adhered to the phosphor, the dispersibility in the photosensitive resin solution is improved, and the characteristics a, b, and c can be satisfied. However, the phosphor particles scattered to the next dot, and the characteristics d and e were not satisfactory. The phosphor surface-treated with potash water glass and zinc sulfate also has a drawback that it cannot sufficiently satisfy all the characteristics a to e.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fluorescent material for a cathode ray tube, which satisfies all the above characteristics and has excellent coating characteristics, and a method for producing the same.

[0010]

Means for Solving the Problems In order to achieve the above object, the present inventors have made intensive studies on a surface treatment substance and a surface treatment method. As a result, all of the above characteristics were successfully satisfied by depositing SiO ₂ on the phosphor for a cathode ray tube by the action of a compound containing indium, zirconium or antimony.

That is, the surface treatment substance attached to the surface of the phosphor is prepared by adding a silicate aqueous solution or a solution containing colloidal silica and indium, zirconium or antimony to an aqueous suspension containing the phosphor, and adjusting the pH. It is a compound which is obtained, and succeeded in obtaining a phosphor for a cathode ray tube having excellent coating properties by subjecting the phosphor to a surface treatment.

In the surface treatment method for obtaining a phosphor of the present invention, the phosphor is treated in the following steps. An aqueous silicate solution or colloidal silica and a solution containing indium, zirconium or antimony are added to the aqueous suspension containing the phosphor. An alkali or an 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 or the like and indium or the like added to the phosphor particles is attached. After that, the phosphor is washed with water, separated,
dry.

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

Here, the compound attached to the surface of the phosphor of the present invention will be described. It has long been known that silica sol aggregates by adding an electrolyte such as zinc sulfate or aluminum sulfate to a solution containing silica sol and adjusting the pH. This reaction is described as being the result of the following three reaction steps (a), (b) and (c), taking, for example, aluminum. (Inorganic chemistry book Si,
P295, Maruzen).

(A) formation of a flocculant by hydrolysis and polymerization of aluminum; (b) destabilization of the sol by specific adsorption of isopolycations that reduces the surface potential of the colloidal particles; (c) Brownian motion or velocity gradient Collision due to movement of colloid particles by

Similarly, in the present invention, for example, when indium is used as an example, when an aqueous solution containing colloidal silica and indium is added and the pH is adjusted, In (OH) ₃ is generated and the colloidal silica is aggregated to form phosphor particles. Attaches to surface. In this state, the compounds adhered to the phosphor particle surface are SiO ₂ .nH ₂ O (n ≧ 0) and In (O
H) ₃ or coprecipitated silica and indium. When the phosphor is separated and dried, SiO ₂ and In (OH) ₃ ,
Alternatively, it is considered that SiO ₂ and In ₂ O ₃ .nH ₂ O (n ≧ 0) or a mixed crystal of silica and indium hydrate adheres.

In any case, in the state where the surface treatment substance is adhered to the phosphor, it is not possible to specify the substance adhering to the surface by a surface analysis device such as X-ray diffraction. As a blank test, a precipitate formed by adding an indium chloride aqueous solution to a solution containing colloidal silica and adjusting the pH to 7.5 with aqueous ammonia was washed with water and separated, and then subjected to 100 ° C. for 3 hours.
The X-ray diffraction patterns of the respective precipitates when dried at 100 ° 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 precipitate is dried under the respective conditions, all the peaks of In (OH) ₃ are detected. When the drying temperature is set to 200 ° C., peaks that cannot be identified other than the peaks of In ₂ O ₃ and In (OH) ₃ appear.

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. 3 shows X-ray diffraction patterns of the respective precipitates when each was dried for 3 hours. In these figures, the peak of In (OH) ₃ is also ●,
The peak of In ₂ O ₃ is indicated by ○. When indium sulfate is used in place of indium chloride, the resulting compound is almost amorphous, and it is difficult to detect a peak.
When dried at 100 ° C. and 150 ° C., a peak likely to be indium hydroxide can be detected.

FIGS. 8 to 10 also show a blank test in which an aqueous solution of antimony chloride (SbCl ₃ ) was added to a solution containing colloidal silica, and the pH was adjusted to 7.5 with aqueous ammonia. The precipitate was washed with water and separated, then 100 ° C, 150 ° C, 200 ° C
3 shows X-ray diffraction patterns of the respective precipitates when each was dried for 3 hours.

It is considered that antimony (III) chloride is partially hydrolyzed in an aqueous solution to form SbOCl. However, when used as a flocculant for colloidal silica, SbOCl can be detected in these X-ray diffraction patterns. Sb ₄ O ₅
A peak likely to be Cl ₂ or Sb ₂ O ₃ is detected.

FIGS. 11 to 13 show a blank test in which a zirconium chloride (ZrCl ₄ ) aqueous solution was added to a solution containing colloidal silica and the pH was adjusted to 7.5 with ammonia water. The precipitate was washed with water and separated.
FIG. 2 shows an X-ray diffraction pattern of each precipitate when dried at 3 ° C. for 3 hours.

In this case, similarly, the peak of ZrO ₂ cannot be detected, and each precipitate is amorphous, and it is not possible to specify what kind of compound the added zirconium is.

In the X-ray diffraction diagrams of the precipitates formed from the colloidal silica and the above-mentioned metal ions shown in FIGS. 1 to 13, some weak peaks appear in some of them. Most of them are considered to be hydrates or basic salts, and it is not possible to specify what kind of compound silica is present because it is amorphous.

The substance adhering to the surface of the phosphor particles of the present invention can be obtained by adding an aqueous solution of silicate or colloidal silica and a solution containing indium, zirconium or antimony to the phosphor suspension. by adjusting the pH, in which indium, S iO ₂ with a compound containing zirconium or antimony attached to the phosphor particle surface.

The phosphor used in the present invention is generally known as a phosphor for a cathode ray tube, and includes a zinc sulfide-based phosphor, a zinc phosphate-based phosphor, a zinc silicate-based phosphor, and yttrium oxysulfide. Phosphors, yttrium oxide phosphors, indium borate phosphors and the like can be used.

As the aqueous silicate solution to be 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 or the like can be used.

As the solution containing antimony, for example, an aqueous solution of antimony chloride, antimony sulfate or the like can be used, and antimony has trivalent or pentavalent, and any of them may be used.

As the solution containing zirconium, for example, an aqueous solution such as zirconium chloride, zirconium sulfate, or zirconium acetate can be used. Zirconium has trivalent or tetravalent, and any of them can be used.

In the present invention, a conventional method of depositing SiO ₂ using an aqueous solution containing zinc, aluminum or the like may be used in combination, and the aqueous solution may contain zinc or aluminum sulfate, chloride or chloride as well as indium. And aqueous solutions of nitrates and the like can be used.

The pH of the phosphor suspension is adjusted by adding a solution containing indium, zirconium or antimony,
It is adjusted in the range of 4 to 10 so that O ₂ is attached to the phosphor particle surface. NaOH, KOH, NH ₄ OH or the like can be used as the alkali added for pH adjustment. CH ₃ COOH, HCl, HNO ₃ , H ₂ SO _{4 and the} like can be used as the acid.

The amount of the aqueous solution or colloidal silica containing silicic acid to be added to the phosphor suspension is contained therein.
The amount is usually adjusted to 0.01 to 3 parts by weight, preferably 0.05 to 1.0 parts by weight, based on 100 parts by weight of the phosphor in terms of the amount of SiO ₂ .

The amount of indium, zirconium or antimony added to the phosphor suspension is contained in the aqueous solution.
In terms of the amount of the metal, the amount is usually adjusted to be 0.0005 to 1.0 part by weight, preferably 0.01 to 0.5 part by weight based on 100 parts by weight of the phosphor. .

Further, when an aqueous solution containing zinc and / or aluminum is added to the phosphor suspension, the amount thereof is also converted to 100 parts by weight of the phosphor.
Each is adjusted to more than 0 part by weight and 0.1 part by weight or less, preferably from 0.001 part by weight to 0.05 part by weight.

The above range is adjusted when the amount of SiO ₂ is at least 3 parts by weight, the amount of indium or the like is at least 1 part by weight, or the amount of zinc and aluminum is at least 0.1 part by weight or the total amount thereof. Is 0.1 part by weight or more, the dispersibility of the obtained phosphor in the photosensitive resin solution is deteriorated.

[0037] In the surface treatment method of the present invention, the SiO ₂ to be added to the phosphor suspension, and indium, zinc, optimum amount of aluminum, the phosphor 100 parts by weight, SiO ₂ is 0. The range is from 08 to 0.8 parts by weight, the content of indium and the like is from 0.03 to 0.5 parts by weight, and the amount of zinc and aluminum is from 0.01 to 0.05 parts by weight.

Further, the surface treatment method of the present invention does not specify the drying conditions of the phosphor to which the surface treatment substance is attached. However, preferably, the drying temperature of the phosphor is preferably adjusted in the range of 80C to 200C. This is because when dried or baked at 200 ° C. or more, the dispersibility of the phosphor tends to deteriorate.

[0039]

FIG. 14 shows that a phosphor suspension containing 100 parts by weight of ZnS: Ag, Al phosphor was colloidal silica 0.1%.
Parts by weight, and further, an aqueous solution of indium sulfate was added at varying amounts to adjust the pH to 7.5.
The surface-treated phosphor of the present invention obtained by washing with water, separating and drying at 150 ° C. for 3 hours, and ZnS: Ag, Al phosphor 1
0.1 parts by weight of colloidal silica was added to the phosphor suspension containing 00 parts by weight, and an aqueous solution of zinc sulfate was further added in varying amounts to adjust the pH to 7.4, followed by washing with water and separation. It is a figure which shows the dispersibility with the conventional surface treatment fluorescent substance obtained by drying at 150 degreeC for 3 hours in comparison.

This figure shows that 7.5 g of the phosphor to which each surface treatment substance was attached was mixed with ammonium bichromate and PVA.
The solution was dispersed in 15 ml of a solution containing a phosphor and a surfactant, placed in a centrifuge tube, and centrifuged at 1000 rpm for 15 minutes, and the sedimented volume represents the dispersibility of the phosphor. Phosphors with excellent dispersibility have a low sedimentation speed and a small sedimentation volume.

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

Table 1 shows a comparison between the surface-treated phosphor of the present invention and the conventional surface-treated phosphor in terms of the rate of peeling of SiO ₂ adhered to the surface. The peeling rate of SiO ₂ was measured as follows.

A predetermined amount of a phosphor is mixed with a normal coating solution containing a dichromate or the like to form a coating slurry, and the coating slurry is refluxed for a certain time by a pump used in an actual cathode ray tube coating process. Later, the phosphor is separated,
After washing with water three times, dry and adhere to the phosphor
Analyzing the ₂ amount, the amount of SiO ₂ had been deposited first, to measure the amount of SiO ₂ was peeled off. In addition, ZnS: Cu, Au phosphor is 0.3% by weight of SiO ₂ , In, Sb, Zr, Zn.
Were attached to each other by 0.05% by weight.

[Table 1]

According to the present invention, the indium, zirconium or antimony added to the phosphor suspension allows the
₂ can be firmly attached to the phosphor surface. Accordingly, since the peeling of SiO _{2 on} the surface of the phosphor is reduced, the dispersibility of the phosphor is improved, haze does not easily occur, and a phosphor for a cathode ray tube having excellent adhesive strength is obtained. Also, a phosphor exhibiting good coating characteristics can be obtained even when conventional zinc and aluminum are used in combination.

[0045]

【Example】

(Examples 1 to 13) The phosphor of the present invention was obtained by the following steps. 200 g of a phosphor for a cathode ray tube is suspended in 600 ml of ion-exchanged water to prepare a phosphor suspension. An aqueous solution containing colloidal silica, granular silica, or silicic acid is added to the phosphor suspension. Tables 2 to 5 show the content of the added silica in terms of SiO ₂ . An aqueous solution containing indium, zirconium or antimony is added to the phosphor suspension. Tables 2 to 5 show the metal contents of the added metal In, Sb, and Zr aqueous solutions and the amounts added. While stirring the suspension, an alkali or an acid is added dropwise to adjust the pH. Thereafter, the stirring is stopped and the mixture is left standing to settle the phosphor. Table 2 shows the type and pH of the acid or alkali to be added.
It is shown in Table 5. After the phosphor has settled sufficiently, the supernatant is discarded, water is added again, and the mixture is left to stir to settle the phosphor. After repeating this operation three times with water, the fluorescent substance is separated by suction filtration using a Nutsche lined with filter paper. Take out the phosphor from Nutsche 80 ℃ -20
Dry at 0 ° C. for 2 to 8 hours. The dried phosphor is passed through a 380 mesh sieve to obtain the phosphor of the present invention, which is then subjected to each inspection.

Tables 2 to 5 show the conditions in the above embodiment. In these tables, the type of the cathode ray tube phosphor to be used, the concentration of the aqueous solution containing silica, the type and the amount added, the concentration of the aqueous solution containing indium and the like,
The type and amount of addition, the type of the alkali or acid to be added dropwise, the pH of the suspension, the drying temperature and the drying time are shown.

[0047]

[Table 2]

[0048]

[Table 3] * 2% In (NO ₃ ) ₃ and 1% Zn (SO ₄ ) _{2 in the} table
It means In content 2% and Zn content 2%.

[0049]

[Table 4]

[0050]

[Table 5] [Comparative Examples 1 to 13] In the steps (1) to (3) of the examples, only the aqueous solution containing indium or the like was replaced with an aqueous solution containing Zn or Al. Obtained. The results 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 Comparative Examples 1 to 13 were prepared by mixing ammonium bichromate, PVA and a surfactant. After dispersing in a photosensitive resin solution containing the solution and applying the solution to a face plate, exposure was performed using a stripe-shaped shadow mask to evaluate the application characteristics.

[Comparison of Sharpness in Coating Characteristics] A stripe formed of a phosphor having excellent dispersibility has straight edges parallel to each other. A stripe formed of a phosphor having poor dispersibility has unevenness at its edge, and becomes a parallel line of a wavy line. Therefore, when the ratio of the wavy line length / linear distance is taken, the ratio of the sharp phosphor is close to 1.

[Comparison of Adhesive Strength of Phosphor] A phosphor slurry is applied to a face plate and dried.
Thereafter, when exposing with a stripe-shaped shadow mask, a transmittance variable filter is provided between the exposure light source and the shadow mask. The stripe width of the phosphor screen formed when exposed with a filter having a transmittance of 100% is 18
It is set to 0 μm, and the light transmittance is gradually reduced to reduce the exposure. As the exposure decreases,
The stripe width of the phosphor screen becomes narrower, and stripping of the stripe eventually occurs. 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 at which peeling starts, the stronger the adhesion of the phosphor.

[Comparison of Haze] This property is obtained by, after exposure and washing, counting the number of remaining phosphors other than stripes per unit phosphor screen (1 mm ² ) by microscopic observation, averaging three places, and obtaining three The following were judged as excellent, 4 or more as good, and 10 or more as unacceptable.
The above measurement results are shown in Tables 10 and 11.

[0059]

[Table 10]

[0060]

[Table 11]

[0061]

As described above, the phosphor for a cathode ray tube according to the present invention has a surface on which Si is attached by the action of a compound such as indium, zirconium or antimony attached to the phosphor.
O ₂ can be firmly adhered, and in addition to dispersibility, it has excellent adhesive strength and can form an excellent phosphor screen with almost no haze.

[0062]

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction diagram of a deposit on the phosphor surface of the present invention.

FIG. 2 is an X-ray diffraction diagram of a deposit on the phosphor surface of the present invention.

FIG. 3 is an X-ray diffraction diagram of a deposit on the phosphor surface of the present invention.

FIG. 4 is an X-ray diffraction diagram of a deposit on the phosphor surface of the present invention.

FIG. 5 is an X-ray diffraction diagram of a deposit on the phosphor surface of the present invention.

FIG. 6 is an X-ray diffraction diagram of a deposit on the phosphor surface of the present invention.

FIG. 7 is an X-ray diffraction diagram of the deposit on the phosphor surface of the present invention.

FIG. 8 is an X-ray diffraction diagram of a deposit on the phosphor surface of the present invention.

FIG. 9 is an X-ray diffraction diagram of the deposit on the phosphor surface of the present invention.

FIG. 10 is an X-ray diffraction diagram of the deposit on the phosphor surface of the present invention.

FIG. 11 is an X-ray diffraction diagram of the deposit on the phosphor surface of the present invention.

FIG. 12 is an X-ray diffraction diagram of the deposit on the phosphor surface of the present invention.

FIG. 13 is an X-ray diffraction diagram of the deposit on the phosphor surface of the present invention.

FIG. 14 is a diagram showing a comparison between the dispersibility of the phosphor of the present invention and a conventional phosphor.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C09K 11/00-11/89 H01J 29/20

Claims (2)

(57) [Claims] To 1. A phosphor particle surfaces, indium, the pH of the aqueous solution containing zirconium or antimony 4-10
A phosphor for a cathode ray tube, wherein SiO ₂ is adhered by the action of a compound obtained by adjusting the thickness of the phosphor. 2. An aqueous solution of silicate or colloidal silica and an aqueous solution containing metal ions are added to the suspension containing the phosphor, and the pH of the suspension is adjusted to 4 to 10 to prepare the suspension of the phosphor. A surface treatment method for attaching a surface treatment substance containing silica to a surface , wherein the aqueous solution containing metal ions is an aqueous solution containing any metal ion of indium, zirconium or antimony.
A surface treatment method for a phosphor for a cathode ray tube to be used as a liquid .