JPH02252767A - Red pigment, pigment-coated phosphor and cathode ray tube - Google Patents

Abstract

PURPOSE:To obtain a red pigment having an excellent brightness and contrast characteristics, comprising a complex compd. of gold and iron represented by a specific formula, and being suitable as the red pigment for a pigment- coated phosphor for a color picture tube. CONSTITUTION:A red pigment comprising a complex compd. represented by the general formula, xAu.Fe2O3 (wherein 0.001<=x<=0.1). The complex compd., being capable of giving an excellent brightness and contrast characteristics, is most suitable as the red pigment for a pigment-coated phosphor for a picture tube. By using as the base of the pigment an iron oxide which, though being capable of improving the contrast only a little, thermally changes its own color slightly, causing gold sulfide to deposit on the surface of the particles of the iron oxide, and annealing the particles in air, the red pigment having a ratio of spectral reflectance at 620-630nm to that at 540-550nm larger than the ratio in the conventionally used red oxide is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a novel red pigment and a pigment-coated phosphor for use in the phosphor screen of a cathode ray tube.

(Prior Art) In order to improve the contrast of images projected on a cathode ray tube, for example, a color picture tube, it is a known technique to use a pigment to reduce the reflection of external light on a phosphor screen. Publication No. 50-56146).

Currently, the most commonly used red pigments are:
It is iron oxide Fe, Ox (hereinafter referred to as red iron oxide) described in JP-A-53-14177, etc., and has excellent heat resistance and chemical resistance (acid and alkali resistance).

(Problems to be Solved by the Invention) However, the above red iron oxide does not have sufficient filter properties, and it is desired to improve the image quality (contrast, luminance, etc.) of a phosphor film formed using a red light emitting phosphor coated with red iron oxide. ing. In particular, it has become clear that compared to other red pigments, the effect of improving contrast is small, and the reduction in brightness of the phosphor due to red iron coating is considerably large.

The present invention solves the problems of the conventional pigment-coated phosphor described above,
The purpose is to obtain excellent brightness and contrast characteristics.

[Structure of the invention]

(Means and effects for solving the problem) As a result of synthetic research on various materials that can be used as red pigments, the present inventors found that the general formula xAu-Fe20
．． It has been found that a composite compound of gold and iron represented by the formula (0.001≦x≦0.1) is most suitable as a red pigment for a pigment-coated phosphor for a color picture tube. In other words, the present invention improves brightness and contrast characteristics by using iron oxide as a matrix, which has little contrast improvement effect, but which does not change the body color thermally, and by precipitating gold sulfide on the surface of the iron oxide particles and annealing in air. An excellent red pigment made of a composite compound of gold and iron has a ratio of 620 to 630 nm/540 to 550, which affects the spectral reflectance characteristics, which is larger than that of conventional red iron.It has substantially the same characteristics as conventional red iron. However, if X exceeds 0.1, the above 620
- The reflectance at 630 nm is extremely reduced, which is undesirable.
Note that the average particle diameter is preferably in the range of 0.1 to 14.

As is clear from this composition, the red pigment of the present invention is a substance that is chemically stable against water and acids, and because it undergoes a firing process during the pigment manufacturing process, it is also stable against heat. , which is extremely effective as a pigment for pigment-coated phosphors. 6 Figure 1 shows the red pigment 0.03Au-Fe of the present invention.
20. This figure shows the relationship between the spectral reflection characteristics of conventional red iron oxide and the spectral reflection characteristics of conventional red iron. The vertical axis in FIG. 1 represents the reflectance in logarithm. Note that this reflectance was measured using an apparatus based on JIS-Z8722.

Further, the red-emitting phosphor coated with the pigment of the present invention is a europium-activated yttrium oxysulfide phosphor.

At least one selected from europium-activated yttrium oxide phosphor and europium-activated yttrium vanadate phosphor, and as shown in the following examples,
It was found that the luminance was higher than that of conventional red-emitting phosphors coated with red iron oxide. The reason for this is presumed to be that by using the gold-incorporated pigment, charge-up due to cathode rays is reduced in the phosphor as a whole, resulting in improved brightness.

As can be seen from Figure 1, the reflectance of the pigment of the present invention is lower overall than that of conventional red phosphor, but the reflectance in the wavelength range of 540 to 550 nm, which has a negative effect on contrast, and the red phosphor Taking the ratio of the reflectance in the vicinity of the emission wavelength of 620 to 630 nm, (this ratio is the reflectance of 540 to 550 nm and 620 to 630 nm in the logarithmic graph of the reflectance in
It is proportional to the difference in reflectance in nm. ) It can be seen that the red pigment of the present invention has significantly better brightness and contrast characteristics. Furthermore, the present invention is characterized by a cathode ray tube equipped with a phosphor film in which the pigment-coated phosphor of the present invention is formed on the inner surface of a panel constituting an envelope. characteristics can be obtained. Therefore, it is possible to improve the fluorescence sensitivity during the formation of the fluorescent film, and also to improve the luminance of light emission.

The pigment coating amount of the pigment-coated phosphor of the present invention is preferably in the range of 0.03 to 5% by weight. If it is less than 0.03% by weight, there is almost no contrast improvement effect.

If it exceeds 5% by weight, the brightness of the phosphor will drop significantly, which is not preferable. Furthermore, the average particle size of the phosphor is

3-10. The range is preferably 4 to 8 μs, and more preferably 4 to 8 μs.

(Example) Hereinafter, the method for producing a red pigment of the present invention will be briefly described. While iron oxide powder is dispersed and stirred in pure water, an appropriate amount of gold chloride oxidation solution is added. Next, ammonium sulfide or an aqueous alkali sulfide solution is added to and mixed with this dispersion to precipitate gold sulfide on the surface of the iron oxide particles. Stirring is stopped, one particle is precipitated, the supernatant liquid is discarded, the particles are washed several times with pure water, and then filtered and dried. This substance has a dark brown body color, and by firing it in air at 400 to 800°C, the red pigment of the present invention can be obtained.

Next, the pigment-coated phosphor of the present invention can be prepared by preparing a pigment dispersion in which the pigment obtained as described above is thoroughly dispersed in a ball mill using balls such as silica balls or alumina balls and pure water. It is manufactured by the method described below. Disperse the europium-activated yttrium oxysulfide phosphor in pure water, add a certain amount of the pigment dispersion of the present invention obtained above, add a specified amount of the zero-order acrylic emulsion, and stir thoroughly. After that, sulfuric acid, liquid acid.

The pH is adjusted to 2 to 4 using a mineral acid such as nitric acid, and pigment particles are attached to the surface of the phosphor particles using an acrylic emulsion as a binder. Pigment coated phosphor thus obtained as required.

After dispersion treatment and surface treatment, it is filtered and dried. After drying, the phosphor is subjected to a sieving process to obtain the pigment-coated phosphor of the present invention.

In addition to the above manufacturing method, other methods are already known.

For example, a method using gelatin and gum arabic (Japanese Unexamined Patent Publication No. 5
3-5088), a method using an acidic polymer and a basic polymer (JP 57-7190), a method using an electrostatic coating method (JP 52-133088)
, a production method using a copolymerization method (Japanese Unexamined Patent Publication No. 53-3980), etc. can be applied.

Hereinafter, the present invention will be explained in detail with reference to specific examples.

Example 1 LOOg of iron oxide is dispersed and stirred in pure water, 120 cc of a 5% chloroauric acid aqueous solution is added thereto, and the mixture is thoroughly stirred.

Next, 20 cc of an aqueous ammonium sulfide solution is added to deposit gold sulfide on the surface of the iron oxide particles. This solid substance is filtered, washed with pure water, filtered and dried. After drying, a 0.03Au-Fe20° red pigment can be obtained by firing at 600°C for 1 hour.

The pigment obtained above is sufficiently dispersed by adding silica balls and pure water to prepare a 10% pigment dispersion.

On the other hand, europium-activated yttrium oxysulfide phosphor IKg
Disperse and stir in 5 liters of pure water, then add 100g of the 10% pigment dispersion prepared earlier and stir well.
Add 2 cc of acrylic emulsion resin (45%), stir, and then adjust the pH to 2.5 with dilute sulfuric acid.

Next, after washing three times with pure water, the solid content is precipitated and dispersed in a ball mill, followed by washing with water, filtration, and drying. After drying, it is sieved through a 400-mesh sieve to obtain a pigment-coated phosphor in which the surface of the europium-activated oxysulfide iodine phosphor is coated with 1% by weight of the pigment of the present invention.

A slurry was prepared using the phosphor of the present invention thus obtained, and applied onto a cathode ray tube panel using a conventional method, and the luminance of the formed phosphor film was measured.

As a result, it was confirmed that the brightness was improved by 9% compared to the pigment-coated phosphor using conventional red iron oxide and having the same contrast characteristics as the present example.

An example of a cathode ray tube provided with a phosphor film made of the above-mentioned phosphor is shown in FIG. 2. The cathode ray tube includes a panel 1, and a funnel 2 and a neck 3 sealed to the panel 1. Then, an envelope 4 is constructed, and an electron gun 5 is inserted into the neck 3.

A fluorescent film 6 is formed on the inner surface of the panel 1, and the electron beam emitted by the electron gun 5 hits the fluorescent film 6.
It emits light when excited.

Example 2 100 g of iron oxide is dispersed and stirred in pure water, 120 cc of a 5% chloroauric acid aqueous solution is added thereto, and the mixture is thoroughly stirred.

Next, 20 cc of an aqueous ammonium sulfide solution is added to deposit gold sulfide on the surface of the iron oxide particles. This solid substance is filtered and washed with pure water, then filtered and dried. After drying, a 0.03Au-FewO1 red pigment can be obtained by firing at 600°C for 1 hour.

The pigment obtained above is sufficiently dispersed by adding silica balls and pure water to prepare a 10% pigment dispersion. On the other hand, 1 kg of europium-activated yttrium oxysulfide phosphor was dispersed and stirred in 5 liters of pure water.
After adding 5 g of pigment dispersion and stirring well, 0.5 cc of acrylic emulsion resin (45%) is added, and after stirring, the pH is adjusted to 2.5 with dilute sulfuric acid. Then, after washing three times with pure water.

After settling the solid content and dispersing it in a ball mill, it is washed with water, filtered and dried. After drying, it is sieved with a 400-mesh sieve to coat the surface of the europium-activated yttrium oxysulfide phosphor with 0.05% by weight of the pigment of the present invention. A coated pigment-coated phosphor can be obtained.

A slurry was prepared using the phosphor of the present invention thus obtained, and applied onto a cathode ray tube panel using a conventional method, and the luminance of the formed phosphor film was measured.

As a result, it was confirmed that the luminance was improved by 8% compared to the pigment-coated phosphor using conventional red iron phosphor and having the same contrast characteristics as the present example.

Example 3 In the same manner as in Example 1, 100 g of iron oxide, 360 cc of a 5% chloroauric acid aqueous solution, and 50 cc of an ammonium sulfide aqueous solution were used to obtain a 0.09 Au-Fe, O, red pigment. The pigment obtained above is sufficiently dispersed by adding silica balls and pure water to prepare a 10% pigment dispersion. On the other hand, 1 kg of eurobium-activated yttrium oxysulfide phosphor was dispersed and stirred in 5 liters of pure water, then 10 g of the 10% pigment dispersion prepared earlier was added, stirred thoroughly, and 2 cc of acrylic emulsion resin (45%) was added. After stirring, adjust the pH to 3 with dilute hydrochloric acid. After washing three times with pure water, the solid content is precipitated and dispersed in a ball mill, washed with water, filtered and dried. After drying, the mixture is sieved through a 400-mesh sieve to obtain a pigment-coated phosphor in which the surface of the europium-activated yttrium oxysulfide phosphor is coated with 0.1% by weight of the pigment of the present invention.

A slurry was prepared using the phosphor of the present invention thus obtained, and applied onto a cathode ray tube panel using a conventional method, and the luminance of the formed phosphor film was measured.

As a result, it was confirmed that the luminance was improved by 6% compared to the pigment-coated phosphor using conventional red iron oxide and having the same contrast characteristics as the present example.

Example 4 In the same manner as in Example 1, 100 g of iron oxide, 10 cc of 5% chloroauric acid aqueous solution, and 2 cc of ammonium sulfide aqueous solution were used to prepare o, oozz^u-Fe, 0. A red pigment was obtained. The pigment obtained by the above method is sufficiently dispersed by adding silica balls and pure water to prepare a 10% pigment dispersion.

1 kg of europium-activated yttrium oxysulfide phosphor
Disperse and stir in 5 liters of pure water, then add 400 g of the 10% pigment dispersion prepared earlier, stir well, and then add 3 cc of acrylic emulsion resin (45%).
After stirring, the pH was adjusted to 2.5 with dilute hydrochloric acid. After washing three times with pure water, the solid content is precipitated, dispersed in a ball mill, washed with water, filtered and dried. After drying, the pigment of the present invention is applied to the surface of the europium-activated yttrium oxysulfide phosphor by sieving through a 400-mesh sieve.
A pigment-coated phosphor with a weight percent coating can be obtained.

A slurry was prepared from the thus obtained phosphor of the present invention and applied onto a cathode ray tube panel by a conventional method, and the luminance of the formed phosphor film was measured.

As a result, it was confirmed that the luminance was improved by 6% compared to the pigment-coated phosphor using conventional red iron oxide and having the same contrast characteristics as in this example.

Example 5 A 10% pigment dispersion of the present invention obtained in Example 1 above is prepared. Europium activated yttrium oxide phosphor 1
kg is dispersed and stirred in 5 liters of pure water, then 80 g of a 10% gelatin solution is added and thoroughly stirred and dispersed. On the other hand 1
10g of 5% gum arabic aqueous solution in 20g of 0% pigment dispersion
Add and stir to disperse. Then, the phosphor dispersion liquid and the pigment dispersion liquid are mixed with stirring, and the pH of the mixed liquid is adjusted to 4 with acetic acid. After pH adjustment, the mixture is cooled to 10° C. or less, and 10 cc of formaldehyde as a hardening agent is gradually added with stirring. After standing, the solid content was washed three times with pure water, and then
Filter and dry at 100°C. After drying, the mixture is sieved through a 400-mesh sieve to obtain a pigment-coated phosphor in which the surface of the europium-activated yttrium oxide phosphor is coated with 0.2% by weight of the pigment of the present invention.

A slurry was prepared from the thus obtained phosphor of the present invention and applied onto a cathode ray tube panel by a conventional method, and the luminance of the formed phosphor film was measured.

As a result, compared to a pigment-coated phosphor with contrast characteristics equivalent to that of this example using conventional red iron oxide, 10%
An improvement in brightness was confirmed.

Example 6 In the same manner as in Example 5, a europium-activated yttrium vanadate phosphor was used, and 0.0% of the pigment of the present invention was applied to the surface of the europium-activated yttrium vanadate phosphor.
A pigment-coated phosphor with a coating of 2% by weight was obtained.

A slurry was prepared from the thus obtained phosphor of the present invention and applied onto a cathode ray tube panel by a conventional method, and the luminance of the formed phosphor film was measured.

As a result, it was confirmed that the luminance was improved by 7% compared to the pigment-coated phosphor using conventional red iron oxide and having the same contrast characteristics as the present example.

〔Effect of the invention〕

According to the invention of claim 1, it is possible to realize a red pigment having excellent chemical resistance and heat resistance.

According to the second aspect of the invention, it is possible to realize a pigment-coated phosphor that has better contrast characteristics and improved luminance compared to conventional pigment-coated phosphors.

According to the third aspect of the invention, a high quality cathode ray tube with good exposure sensitivity can be realized.

[Brief explanation of drawings]

FIG. 1 shows a red pigment of the present invention, 0.03 μm u-Fe,O. FIG. 2 is a cross-sectional view schematically showing a cathode ray tube. 1... Panel 4... Envelope 6... Fluorescent film agent Patent attorney Nori Chika Ken Yudo Take Hana Kikuo reflection

Claims (3)

[Claims] (1) General formula xAu・Fe_2O_3 (where x is 0
．． 001≦x≦0.1). (2) In a pigment-coated phosphor in which the surface of phosphor particles is coated with a pigment, the pigment has the general formula xAu.Fe_2O.
A red pigment represented by _3 (where x is 0.001≦x≦0.1) is selected from europium-activated yttrium oxysulfide phosphor, europium-activated yttrium oxide phosphor, and europium-activated yttrium vanadate. A pigment-coated phosphor comprising at least one type of phosphor coated with 0.03 to 5% by weight. (3) A cathode ray tube comprising a phosphor film formed of the pigment-coated phosphor according to claim 2 on the inner surface of a panel constituting an envelope.