SU924075A1 - Method for producing phosphors based on zink or zink and cadmium sulphides - Google Patents

Description

The invention relates to a technology for the production of phosphors based on zinc or zinc and cadmium, which are used in the electronic industry for the manufacture of screens of electron-optical converters and ⁵ picture tubes of black-and-white and color television, as well as in the manufacture of inorganic paints.

A known method of producing zinc sulfides and cadmium by their deposition from solutions of salts, such as sulfates, hydrogen sulfide. Precipitation is carried out by bubbling hydrogen sulfide through a solution of salt with stirring [1].

However, to obtain sufficient precipitation of zinc sulfide uniformly dispersed composition of the present method is required stabilization uelo- _m Vij deposition on the pH and salt concentration and the presence in the solution of surfactant.

In addition, hydrogen sulfide is a toxic, flammable and explosive gas. ,.

There is also a method of producing phosphors based on zinc or zinc and cadmium sulfides by calcining a mixture of oxides of the indicated metals, sulfur, activator compounds - copper and silver, a coactivator and fluxes at 750- $ 50 ° C, followed by washing and drying of the obtained product [2].

The disadvantage of this method is that when it is used, cathodoluminophores with a small particle size are obtained in a narrow range from 0.1 to 1.5 μm, which limits or even makes it impossible to use the phosphor in industry.

In industry, for various purposes, phosphors are used, characterized by different particle size distributions. For half-screens of electron-optical converters3 92407!

With high resolution, phosphors with a high content of fine fractions from 1 to 3 μm must be used. Grains less than 1 micron in size prevent a good screen structure.

For color television picture tubes, phosphors are required, containing mainly particles no larger than 14 and no less than 2 microns in size. Grains ₁₀ of 2 μm in size create a veil on the screens of color television picture tubes, which prevents the production of pure colors. To screen kinescope black and white television, and URD ₅ GIH devices used in the electronic industry and for the manufacture of inorganic inks also require phosphors-powders with a strictly regulated ₂₀ degrees of dispersed NOSTA.

In the known method, the feedstock is not characterized by the degree of dispersion and the possibility of obtaining sulfide phosphors of ₂₅ ditches with a large grain size and with a given fractional composition is not provided.

The purpose of the invention is to increase the output of phosphors based on zinc or zinc and cadmium sulfides with a predetermined dispersion composition for screens of electron-optical converters, color and black-and-white television picture tubes and other intended purposes, depending on the dispersion of these sulfides.

This goal is achieved by the method of producing phosphors based on zinc or zinc and cadmium sulfides by heat treatment of a charge from oxides of the corresponding metals with a specific surface area corresponding to the dispersion of the target product, sulfur, compounds of activators and co-activator and fluxes, at 600 “700 ° C, followed by calcination of the obtained product, washing and drying it.

Moreover, to obtain a phosphor based on zinc and cadmium sulfide for screens of electron-optical converters with a particle size of ⁵⁰ up to 4 μm and at least 60%, zinc oxide with a specific surface of 7 “9 M7G is taken and the charge is calcined at 700-800 ° С in the air.

To obtain green phosphors of ⁵⁵ luminosity based on zinc and cadmium sulfides for screens of color television picture tubes with a content of particles ranging in size from 3 to 10 μm, 70-90% zinc oxide is taken with a specific surface of 2-4.5 m ^ / g and calcination carried out at 900-1000 ° C under coal. ·

- To obtain a yellow-green phosphor of a glow based on zinc and cadmium sulfides with a particle content of up to 3 μm not more than 15%, zinc oxide is used with a specific surface of not more than 3.5 m ^ / g and calcination is carried out at 750-850 ^ 0 in air .

To obtain a blue phosphor based on zinc sulfide and a yellow phosphor based on zinc and cadmium sulfides, the starting zinc oxide is used as a component for black-and-white television with a specific surface area of 4.3 to 7.0 and 4.3 to 5.5 μ ^ί / γ and calcination are carried out in air at 850-950 and 700-800 ° С, respectively, for 1-2 hours.

The difference of the proposed method lies in the fact that zinc oxide in the initial charge is used with a specific surface corresponding to the dispersion of the target product, and the charge is heat treated at 600-700 ° C before calcination.

Additional distinguishing features of the method are determined by the fact that zinc oxide is used with a specific particle size to obtain the specified phosphors for the intended purpose and the charge is calcined under appropriate conditions.

In this case, to obtain phosphors of yellow and blue color, the use of zinc oxide with a specific specific surface and particle size and a certain calcination temperature is provided.

The degree of dispersion of zinc oxide powder by this method, subject to preliminary heat treatment of the mixture, thus determines the particle size distribution of the resulting phosphor and, accordingly, its color properties and purpose.

In the process of heat treatment of the mixture at 6 ° C ~ 7 ° C, sulfonation of zinc oxide occurs, and with subsequent calcination, the formation of luminescent properties and crystal growth.

The indicated heat treatment interval promotes a more complete conversion of the starting oxide to sulfide; at higher temperatures, the starting zinc oxide particles are coated from the surface with a continuous film of zinc sulfide, which prevents further sulfonation of the oxide.

In this case, the dispersion of the initial zinc oxide is characterized by the specific surface, since it is almost impossible to determine its particle size distribution by the size of the particles. Powders with a larger specific surface have a smaller particle size and vice versa. Different batches of zinc oxide have a specific surface area of 2 to 9 m / g. To obtain zinc oxide with a specific surface of more than 2 and less than 9 m ^ / g, different powders of zinc oxide are mixed in the required ratio.

Similarly treated with powders of cadmium oxide or cadmium salt, decomposing to oxide by calcination.

In the case of the manufacture of phosphors for screens of electron-optical converters, zinc oxide is used with a specific surface area of 4.3 to 9 M7G, which makes it possible to obtain phosphors with the required grain size, namely from 40 to 80% of particles no larger than 4 microns, and with a structure grain providing a good packaging of the screen coating. In this case, there are practically no particles smaller than 1 μm.

Zinc oxide ^ with a specific surface area of less than 4.5 m / g cannot be used for these purposes, since the yield of the fine fraction decreases and the screen structure of the electron-optical converter and its resolution deteriorate.

In the case of the preparation of phosphors for color television screens, zinc oxide with a specific surface area of 2.0 to 4.5 m ^ / g is used.

In this case, the range of particle size distribution decreases, i.e. The phosphor contains a larger number of particles of one fraction, namely 70 ~

80% of particles ranging in size from 3 to 10 microns, which meets the requirements for these phosphors. In some cases, phosphors with a fraction of particles up to 3 μm of no more than 15% are prepared for screens of special tubes, while zinc oxide with a specific surface of not more than 3.5 m ^ / g is used <0. ¹

Thus, the use of zinc and cadmium oxides with different specific surfaces can significantly expand the range of phosphors made from them, and eliminates the fractionation operation.

Phosphors obtained from oxides are not inferior in luminosity and color coordinates to phosphors obtained from sulfides, and surpass the latter in particle structure and particle size distribution.

Example 1. Mix 345 g of cadmium oxide, 655 g of zinc oxide with a specific surface of 8 m ^ / g, g of activated enriched charge · Ζη8 - Λβ · аaCl, containing, g:

Ζηδ 100, Αβ 0.8, MaCl 100, and 400 g of sulfur. The mixture is calcined in air at 650-670 ° C for 45 minutes and then 750-800 ° C for 60 minutes. The resulting product is washed with acetic acid and then with water to pH = 7.0.

The phosphor is washed on a Buchner funnel and dried at 170 ° C.

The resulting phosphor contains 70% of particles up to 4 μm in size with a brightness and color of luminescence the same as that of a phosphor prepared on a sulfide basis, composition Ζηδ 5-5 · '

- С <] 5 ₄₅ · Αβ (8 · 10 ' ⁹ %) Ν; ιίΙ (1%) and containing 24% of particles up to 4 microns in size.

PRI me R. 2

830 g of zinc oxide with a capacity of 9 m * / g, 170 g of cadmium oxide with a specific surface of 2 m ^ / g, 20 g of activated enrichment mixture Ζηδ - Αβ · Masl composition, g: Ζηδ 100,

Αβ 0.8 in the form of silver nitrate, ΝίΐϋΙ 100 and 380 g of sulfur.

The mixture is calcined in air at 65 ° ^- 67 ° C for 45 minutes and then at 780-880 ° C for 60 minutes. The phosphor is washed with acetic acid and then with water to pH = 7.0. The resulting phosphor contains 75% of particles up to 4 microns in size.

Example 3 - Prepare a mixture analogously to example 2, but zinc oxide is taken with a specific surface

3.5 m ^ / g. The resulting phosphor contains 48% of particles up to 4 μm.

Example 4. Mix 900 g of ₄ zinc oxide with a specific surface of m ^ / g, 100 cadmium oxide, 10 g of enriched charge Ζηδ-Cu *. A1 composition,

The specific surface area is mixed over 92 * 1075 g: Ζη5 100, Cu 0.8, ΑΙ 1.2 in the form of chlorides and 1.09 kg of sulfur.

The mixture is calcined under a low-carbon sleep at 700, and then at. 9θ0 ^ο 0. The resulting phosphor for color television has a particle division:

Size, microns oz o- * "

0-6 th 0-14 next distribution% of particles 3

Example 5. To prepare the blue components of the black-and-white television 15 mixed 1 kg of zinc oxide with a specific surface area of 5 »5 m ^ / g 15 g of sodium chloride, 5 g of magnesium chloride and 10 g of a concentrated mixture Ζηδ · Αβ containing, g: 20

Ζηδ 100 and Αβ 0.5 and 590 g of sulfur.

The mixture is calcined in air, first at 700 ° C for 1 h, and then at 900 ^σ 0 for 2 h. The phosphor is washed with acetic acid and 25 water to pH = 7.0. The resulting phosphor has the following particle distribution:

Size, microns % particles 0-4.7 8 thirty 0-6.6 21 0-16 86 16 14

Example 6. The same as in Example 5, but zinc oxide is taken with a specific surface area of 4.3 m7 g.

The resulting phosphor has the following

total particle distribution: Size, microns Up to 4.7 Up to 6.6 Up to 16 % particles 5 16 82 18 For cooking 40 Etc 16 and mer 7. yellow white Components television phosphor black mixed 510 g 45

surface area zinc oxide

5.5 m ^g / g, 490 g of cadmium oxide (or 660 g of cadmium carbonate), 12 g of sodium chloride, 10 g of concentrated 50 charge (containing 100 g of Ζηδ and 0.3 g of Αβ), 490 g of sulfur. The mixture is calcined at 65 ° C. for 1 hour and then at 800 ° C. for 1 hour. The phosphor is treated with acetic acid and 55 washed with water.

The resulting phosphor has the following particle distribution:

Size, μm 0-4.7 0-6.6 0-16% of particles 18 30 95 5

Example 8. Same as in example 8, but zinc oxide was taken with a specific surface of 4.3 m ^ / g.

The resulting phosphor has the following particle distribution:

Size, microns% of particles

0-4.7 thirteen 0-6.6 23 0-16 89 16 eleven

Example 9 · For the preparation of inorganic paints of yellow-orange (I), orange (II) and red-orange (III) colors, batches of the following compositions are prepared, g:

I II

ΖηΟ 544 490

III

416

saso ₃ 366 430 540 ΜβδΙ ^ 122 125 122 SASTs 5 5 5 Si 40 40 40 as enriched charge) 5 500 500 500

Zinc oxide is taken with a specific surface area of at least 3 m ^ / g.

Calcination of the charge is carried out first at 6 ° C for 2 hours, and then at 650-750 ^σ 0 for 2/3 hours in air.

Example 10. The same as in example 5, but zinc oxide is taken with a specific surface area of 4.3 m ^ / g.

The resulting phosphor has the following particle distribution:

Size, microns% of particles

oh 4 0-4 . 24 0-10 92 0-14 96

In the table. 1-3 shows data on the particle size distribution of sulfide phosphors depending on the specific surface area of the initial zinc oxide.

92 * »075 Yu

Table 1

Dependence of the particle size distribution of the phosphor Ζηδ ^^ * Аg · 1аС1 on the specific surface of zinc oxide

The specific surface of zinc oxide, m ¹ / g % phosphor particles in size, microns 0-3 0-4 0-6 0-10 0-14 2.10 6 12 57 89 95 3,55 fifteen 34 72 90 93 4.30 20 42 80 90 93 5.50 25 fifty 82 90 93 6.94 34 66 84 90 93 9.00 45 80 89 54 95

Note. The modes of heat treatment and calcination are 65 ° C and 75 ° C.

table 2

Dependence of the particle size distribution of the phosphor Ζηδ · Cu ‘A1 (C1) on the specific surface of zinc oxide

Specific% of phosphor particles in size, microns

zinc oxide surface, m ^ / g 0-3 0-4 0-6 0-10 0-14 2.10 2 ¹² 54 91 96 2,55 4 thirteen 58 89 95 3,55 3 thirteen 59 92 94 4.30 5 19 65 91 95 4,50 7 25 bz 90 96 5.50 40 78 95 99

Note. Modes of heat treatment and calcination of 700 and E80 ° C

1

Table 3

Dependence of the particle size distribution of the phosphor Ζη5 Α Αβ · MaC! * ΜβίΤ ^ on the specific surface of zinc oxide

The specific surface of zinc oxide, m ν g ' % phosphor particles in size, microns 0-4.7 0-6.6 0-16 16 3,55 2 10 71 29th 4.30 5 16 82 18 5.50 8 21 86 14 6.94 12  27 90 10 9.00 18 32 93 7

Note Heat treatment and calcination modes

The technical and economic advantage of the invention is determined by reducing the loss of sulfide phosphors based on zinc or zinc and cadmium sulfides by eliminating the operation of fractioning the phosphor and eliminating the irretrievable loss of particles not ₃₀ corresponding in size to the requirements of the standard. Moreover, the phosphors of the present invention have a more uniform particulate composition and better grain structure that an increase of the quality of creases ₃₅ screens.

Claims (5)

Formula inventions "About 1. A method of producing phosphors based on zinc sulfide, or zinc and cadmium, comprising the calcination of the charge of the respective metal oxides, sulfur compounds activators trench _45, the co-activator and smoother, followed by washing and drying the resulting product, characterized in that in order to increase the yield a phosphor with a given dispersion composition, zinc oxide in the initial charge is used with a specific surface corresponding to the dispersion of the target product, and the mixture is heat treated before calcination at 6 ° -7 ° C. ⁵⁵ 2. The method according to claim 1, characterized in that for the production of phosphors based on zinc sulfide 700 and 900 C and cadmium for screens of electron-optical converters with a particle size of up to L micron of at least 60%, zinc oxide is taken with a specific surface of 7 “9 m ^ / g and the mixture is calcined at 700800 ° C in air. 3. The method according to claim 1, characterized in that to obtain a green phosphor of a glow based on zinc and cadmium sulfides for screens of color television picture tubes with a particle content of 3 to 10 μm, 70-90% zinc oxide is taken with a specific surface of 2 -4.5 M7G and calcination is carried out at 900-1000 ° C under coal. 4. The method according to p. 3.6 μm not more than 15% zinc oxide is used with a specific surface of not more than 3.5 m ^ / g and calcination is carried out at 750-850 ° C for an hour in air. 5. The method according to π.1, with the fact that to obtain a blue phosphor of zinc sulfide and a yellow phosphor based on zinc sulfides and cadmium as components of a phosphor for black-and-white television, the initial zinc oxide is used with a specific surface area of 4.3 to 7.0 and 4.3 to 5.5 m ^ / g 92 * 4075 and calcination are carried out in air at 850-950 and 700-800 ° C, respectively, for 1-2 hours. "