JPH0625351B2 - Green light-emitting phosphor with pigment - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a green light emitting phosphor having pigment particles attached to its surface (hereinafter referred to as a pigmented green light emitting phosphor), and more particularly to a pigmented green light emitting phosphor used in a high contrast cathode ray tube for television.

[Prior art]

When green pigment particles, blue pigment particles and red pigment particles are respectively attached to the particle surfaces of the green light emitting phosphor, the blue light emitting phosphor and the red light emitting phosphor of the cathode ray tube for television, the color filter of those pigment particles is obtained. Due to the effect, a part of the undesired visible region of the emission spectrum is cut, the color purity of the emission color is increased, and the reflected light is reduced due to the absorption effect of external light by the pigment particles, so that the image contrast is improved. It is known to make a dramatic improvement (Japanese Patent Laid-Open No. 50-56146). Conventionally, blue pigments such as ultramarine blue or cobalt blue are used for blue light emitting phosphors, red pigments such as cadmium selenide, red lead, and red iron oxide are used for red light emitting phosphors, and chromium oxide is used for green light emitting phosphors. (Cr ₂ O ₃ ) and TiO ₂
-ZnO-CoO-NiO pigment (JP-A-53-1360)
No. 39) is known.

[Problems of the prior art]

The conventional green pigment attached to the surface of the green light emitting phosphor used in the high contrast cathode ray tube for television has a large particle size. A green pigment having a large particle size does not exert a sufficient color filter effect with respect to the amount of adhesion, and many pigments must be used to expect the same color filter effect. Conventional green pigment particles have an average particle size of about 0.1 to 0.5 μm, and a phosphor of about 4 to 10 μm. In this case, the pigment particles cannot be said to be sufficiently smaller than the phosphor particles, and the expected filter effect cannot be exhibited unless a considerably large amount of pigment is used. In addition, if the pigment particles are large, there is an adverse effect that they are easily separated from the phosphor. Delamination from the phosphor surface is an important issue for pigmented green emitting phosphors. This is because, when the pigment is peeled off, not only the ability to reproduce a desired contrast or color tone of the color television cathode ray tube screen is deteriorated, but also color mixing on other color dots or stripes,
The so-called "fogging" is likely to occur. Also, more adhesive is needed to control delamination, which often degrades coating properties for cathode ray tube faceplates.

[Means for Solving the Problems]

The present inventors repeated a number of experiments on cobalt blue, which has been conventionally used as blue filter particles on the surface of a blue light emitting phosphor, and as a result, cobalt blue represented by (CoO) n.Al ₂ O ₃ was obtained. , N value of 1 or more was used and the average particle diameter was limited to a specific range, whereby a green pigment for a phosphor, which is superior to conventional green pigments, could be realized. It is known that the color of the (CoO) n.Al ₂ O ₃ pigment changes depending on the value of n. The value of n is small, 0.5
In the following, a bright blue color is given, and a deeper blue color is given in 0.5 to 1.0, which is used as a blue pigment of cobalt blue. However, when n is 1.0 or more, the color is green and the lightness is low, and the entire color is dark green. As shown in FIG. 2, cobalt blue having an n value of 1 or more is a conventional preferable green pigment of TiO ₂ —ZnO—.
Compared with CoO-NiO pigment, the reflectance is extremely low,
It is hard to imagine a preferable green pigment. In particular, TiO ₂ -Z
The nO-CoO-NiO pigment shows excellent reflectance in the green range of 500 to 550 nm, whereas (CoO) n.Al ₂ O ₃ with n = 1.52 has a much higher reflectance in this range. It doesn't get expensive. Therefore, cobalt blue, which has a high n value, has a dark green color as a whole, and never exhibits desirable characteristics as a green pigment. However, the inventors of the present invention realized a phosphor having a contrast superior to that of the conventional phosphors by forming, as fine particles, a unique cobalt blue having a high n value, which does not show excellent characteristics, on the surface of the phosphor. I succeeded in doing so. Therefore, the green pigment used in the present invention has a value of n represented by (CoO) n.Al ₂ O ₃ of 1.0 to 2.6, preferably n is 1.2 to 2.0. Uses a green pigment. What is more characteristic is that (CoO) n · used in the present invention.
The Al ₂ O ₃ green pigment has an average particle size of 0.001 to 0.001.
It is adjusted within the range of 0.1 μm and is extremely thin as compared with the conventional green pigment. On the other hand, the green light-emitting phosphors used in the pigmented phosphor of the present invention are all phosphors whose emission color is green, for example, copper-activated chlorine co-activated zinc sulfide phosphor (ZnS: Cu, Cl),
Copper-activated aluminum co-activated zinc sulfide phosphor (ZnS: C
u, Al), copper and gold activated aluminum co-activated zinc sulfide phosphor (ZnS: Cu, Au, Al), gold activated aluminum co-activated zinc sulfide phosphor (ZnS: Au, Al), copper activated Chlorine co-activated zinc cadmium sulfide phosphor [(Zn, C
d) S: Cu, Cl], copper activated aluminum co-activated zinc cadmium sulfide phosphor (Zn, Cd) S: Cu, A
l), self-activated zinc oxide phosphor (ZnO: Zn), manganese activated zinc silicate phosphor (Zn ₂ SiO ₄ : Mn),
Manganese-activated arsenic co-activated zinc silicate phosphor (Zn ₂ Si
O ₄ : Mn, As) and the like, and all of them can be used. The preferable reflectance of (CoO) n.Al ₂ O ₃ attached to the surface of the phosphor of the present invention and showing particularly excellent characteristics is the region surrounded by the curves a and b in FIG. However, in the measurement of FIG. 1, the reflectance of the barium sulfate powder was set to 100%. The reflectance is measured by barium sulfate powder or (Co
O) n.Al ₂ O ₃ powder is pressed by a glass plate with a smooth surface at a surface pressure of 10 kg / cm ^{2 to} a sufficient thickness, and the reflectance of the pressed surface is measured using an integrating sphere. did. At the time of measurement, the light was illuminated almost perpendicularly to the surface of the material, and the light diffusely reflected in all directions except the direction of the specularly reflected light was integrated and received. The illumination light does not include a ray having an inclination of 5 degrees or more with respect to the center line of the illumination ray bundle, and the inclination of the center line of the illumination ray bundle should be within 10 degrees with respect to the normal to the sample surface. It was measured. On the surface of the above-mentioned green light emitting phosphor, (CoO) n.Al ₂ O ₃
The method for producing the green light-emitting phosphor with pigment by adhering the green pigment particles may be any of an inorganic adhesive method, an inorganic / organic adhesive common method, and an organic adhesive method.

[Action]

FIG. 2 shows that the (CoO) n.Al ₂ O ₃ -based green pigment (curve a) used in the pigmented green light-emitting phosphor of the present invention and the conventional green pigment have a relatively high contrast effect. 3 shows a spectral reflectance curve of a (TiO ₂ —ZnO—CoO—NiO) -based green pigment (curve b) that is used. From this figure, the conventional green pigment represented by the curve b has a high reflectance in the range of 500 nm to 550 nm, which corresponds to green emission, and a low reflectance in the range of 500 nm or less or 550 nm or more. It is expected that the effect of the green pigment attached to the surface of the green light emitting phosphor used in the high contrast cathode ray tube for John as a filter material is excellent. On the other hand, the green pigment used in the phosphor of the present invention has a lower reflectance as a whole as compared with the curve b, as shown by the curve a, and the body color is dark green. Seems unsuitable. However, the present inventor has conducted experiments to find that the (CoO) n.Al ₂ O ₃ -based green pigment used in the present invention has a very small average particle size of 0.001 to 0.1 μm, as compared with the conventional green pigment. By doing so, it was discovered that the hiding power of the phosphor surface can be increased and the reflectance is low, so that an excellent contrast effect can be obtained with a small amount of adhesion. In FIG. 3, a green pigment with n = 1.52, namely (Co
O) _1.52・ Al ₂ O ₃ green pigment and conventional pigment (TiO 2
_(2- ZnO-CoO-NiO) -based green pigment is separately attached to the surface of ZnS: Cu, Al green light-emitting phosphor, and the relative reflectance is shown with respect to the attached amount. Here, the specific reflectance was measured by the following method. 3124K
The sample is irradiated with a light source having an energy distribution of 3 and the tristimulus value (CIE colorimetric method) of reflected light at 380 to 780 nm is measured. Calculate for the amount of pigment attached. As described above, the (CoO) _1.52 · Al ₂ O ₃ -based green pigment (curve a) has only 1/3 to 1/4 that of the conventional TiO ₂ —ZnO—CoO—NiO green pigment (curve b). The amount shows the same relative reflectance. Thus, the green pigment used in the present invention (Co
O) n.Al ₂ O ₃ -based green pigment particles can reduce the amount of adhesion as compared with the conventional green pigment, so that the amount of peeling also decreases according to the amount of adhesion, and thus the cathode ray tube for a color television. Retains the ability to reproduce the excellent color tones of the screen,
Color mixing on other color dots or stripes can be suppressed. In addition, not only the pigment but also the required adhesive can be reduced, so that the coating characteristics are significantly improved, which is very advantageous for manufacturing a cathode ray tube. Next, for use in the present invention _{(CoO) 1.52 · Al 2 O} 3 based green pigment, and a conventional _(TiO 2 -ZnO-CoO-N
iO) based green light-emitting phosphor, ZnS: Cu. The contrast of the pigmented phosphor attached to the Al green light emitting phosphor was compared. As a contrast comparison method, relative emission brightness and relative reflectance were measured for various amounts of pigment attached. The results are shown in FIG. In this case, the relative reflectance and the relative light emission brightness of the phosphor to which the pigment is not attached are set to 100%. From FIG. 4, the green light-emitting phosphor with a pigment of the present invention (curve a)
In the practical range of the relative reflectance of 60% to 100%, the relative emission brightness is higher than that of the conventional phosphor (curve b),
That is, it can be seen that the contrast is high. In addition to this, a heating process at 450 ° C. is included in the cathode ray tube manufacturing process, and due to this heating, there is often a problem that the brightness of the conventional phosphor is lowered. The cause is the thermal stability of the attached pigment. The phosphor of the present invention in which the (CoO) _{1.52.Al 2} O ₃ green pigment used in the present invention is adhered to the ZnS: Cu, Al green light emitting phosphor, the result of the heating test at 450 ° C. for 30 minutes shows the brightness Although the decrease is 1%, TiO ₂ —ZnO—Co
The conventional phosphor in which the O—NiO green pigment is attached to the ZnS: Cu, Al green light emitting phosphor is the same as the result of the heating test.
The brightness was reduced by 8%. As described above, the phosphor of the present invention can improve the contrast by adhering a small amount of the pigment on the surface, and has a greater contrast effect than the phosphor having the conventional green pigment adhered. Also, by reducing the amount of pigment adhesion, the amount of adhesive can be reduced, and as a result, the coating characteristics are improved. In addition, (CoO) n ・ Al
_{The 2} O ₃ -based pigment has high thermal stability, is less likely to cause a decrease in the brightness of the phosphor, and has obtained good results.

[Preferred embodiment]

Examples of the present invention will be described below. Example 1 0.1 part by weight of potassium silicate (K ₂ SiO ₃ ) was dissolved in water to prepare a 0.05% aqueous solution. In this 0.05% aqueous solution, a copper-activated aluminum co-activated zinc sulfide green light-emitting phosphor (ZnS: Cu, Al) 100 having an average particle size of 7 μm was added.
Parts by weight were added and sufficiently dispersed until primary particles were obtained using a stirrer. Thus, a phosphor dispersion liquid was obtained. On the other hand, 0.0005 parts by weight of potassium silicate was dissolved in water to prepare a 0.001% aqueous solution. This 0.001%
Aqueous solution with average particle size of about 0.008μm (CoO)
_0.12 parts by weight of 1.52.Al ₂ O ₃ green pigment particles (manufactured by BASF) were added and sufficiently dispersed by a ball mill until uniform. Thus, a pigment particle dispersion liquid was obtained. Next, the phosphor dispersion liquid and the pigment particle dispersion liquid are mixed while stirring, and aluminum nitrate [Al (NO ₃ ) ₃ ] 0.005 is added.
Parts by weight were gradually added. Then, the pH of the mixed solution was adjusted to 7. After standing, the supernatant was removed by decantation, the precipitate was washed with water, the water was sufficiently removed by filtration, and then dried to obtain the pigmented green-emitting phosphor of the present invention. For comparison, green pigment particles (CoO) _1.52
Instead of Al ₂ O ₃ green pigment particles (TiO ₂ —ZnO
Using the —CoO—NiO) -based green pigment particles, a conventional pigmented phosphor was manufactured in exactly the same manner as described above. Example 2 0.1 part by weight of potassium silicate was dissolved in water to give 0.05%
An aqueous solution was prepared. To this 0.05% aqueous solution, 100 parts by weight of a copper-activated aluminum co-activated zinc sulfide green light-emitting phosphor (ZnS: Cu, Al) having an average particle diameter of 7 μm and 0.5 parts by weight of an acrylic emulsion were added. Using a stirrer, the particles were dispersed sufficiently uniformly to form primary particles. Thus, a phosphor dispersion liquid was obtained. On the other hand, 0.0025 parts by weight of potassium silicate was dissolved in water to prepare a 0.0025% aqueous solution. This 0.002
A 5% aqueous solution having a mean particle size of about 0.008 μm (Co
O) _0.52 parts by weight of _1.52 Al ₂ O ₃ green pigment particles were added and sufficiently dispersed until uniform. Thus, a pigment particle dispersion liquid was obtained. Next, the phosphor dispersion liquid and the pigment particle dispersion liquid were mixed with stirring, and 0.05 part by weight of aluminum nitrate was gradually added. Then the pH of the mixture
The value was adjusted to 7. After standing, the supernatant was removed by decantation, the precipitate was washed with water, the water content was sufficiently removed by filtration, and then dried to obtain a pigmented phosphor of the present invention. Example 3 0.5 part by weight of carboxymethyl cellulose was dissolved in water to prepare a 0.25% carboxymethyl cellulose aqueous solution. This 0.25% aqueous solution has an average particle size of 7μ.
100 parts by weight of copper-activated aluminum co-activated zinc sulfide green light-emitting phosphor (ZnS: Cu, Al) of m were added and sufficiently dispersed until primary particles were obtained using a stirrer. Thus, a phosphor dispersion liquid was obtained. On the other hand, 0.0035 parts by weight of carboxymethyl cellulose was dissolved in water to prepare a 0.0035% aqueous solution. This 0.0035% aqueous solution has an average particle size of about 0.008.
0.7 parts by weight of (CoO) _{1.52.Al 2} O ₃ green pigment particles having a size of μm were added and sufficiently dispersed by a ball mill until uniform. Thus, a pigment particle dispersion liquid was obtained.
Next, the phosphor dispersion liquid and the pigment particle dispersion liquid were mixed while stirring. Thereafter, the water content was sufficiently removed by filtration and then dried to obtain the pigmented phosphor of the present invention.

【The invention's effect】

The pigmented green light-emitting phosphor of the present invention is a green pigment particle whose body color is specified by using cobalt aluminate of the specified cobalt composition, and further, the average particle diameter of the green pigment particles is small. Have been identified. The general formula is (CoO) n
The cobalt aluminate used as Al ₂ O ₃ becomes bright blue when the value of n is 0.5 or less, and deep blue when it is in the range of 0.5 to 1. Cobalt aluminate is used for blue pigments with an n value in the range of 0.5 to 1. When the value of n is larger than 1, as shown by the curve b in FIG. 1, the total reflectance is significantly reduced in the visible light region. Looking at the reflection characteristics, it does not show the filter-like characteristics that can be used for pigments. However, when the average particle diameter of this cobalt aluminate was set to a specific range and it was attached to the surface of the green light emitting phosphor, an extremely excellent property that is superior to the properties of the conventional pigmented green light emitting phosphor, that is, conventional We succeeded in further improving the contrast compared with the conventional pigmented green light-emitting phosphor by attaching a very small amount of pigment, which is a fraction of the above. Furthermore, since the pigmented green light-emitting phosphor of the present invention can improve the contrast with a small amount of pigment, it is possible to effectively prevent the harmful effect of the pigment peeling from the phosphor surface. The peeling of the pigment from the phosphor particles reduces the ability of the cathode ray tube for a color television to reproduce the contrast or color tone. In addition, color mixing on other color dots or stripes,
Causes so-called "fog". In order to suppress peeling,
The use of a large amount of adhesive deteriorates the coating characteristics for the cathode ray tube face plate. Since the pigmented green light-emitting phosphor of the present invention has excellent characteristics by reducing the amount of pigment adhered, it is possible to reduce peeling of the pigment by using a small amount of adhesive. Therefore, without deteriorating the coating characteristics,
Achieves a feature that can minimize fogging.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows preferable characteristics when attached to the surface of a phosphor (C
oO) graph showing reflectivity of n · _Al 2 _{O 3,} Figure 2 shows the spectral reflectance of the are _{(CoO) n · Al 2 O} 3 phosphor and conventional green pigment used in the present invention the graph, the Fig. 3 is a graph showing the relative reflectance of the phosphor with respect to the amount of green pigment attached,
FIG. 4 is a graph showing the relative reflectance of the present invention and the conventional phosphor.

Claims (8)

[Claims] 1. The surface of a green-emitting phosphor has the general formula (Co
O) n.Al ₂ O _{3 In the} pigmented green light-emitting phosphor formed by adhering green pigment particles, the value of n in the general formula is specified in the range of 1.0 ≦ n ≦ 2.6, and The average particle size of the green pigment particles is 0.001
A green light-emitting phosphor with a pigment characterized by being specified to 0.1 μm. 2. The pigment-containing green light-emitting phosphor according to claim 1, wherein the value of n is within the range of 1.2 ≦ n ≦ 2.0. 3. The reflectance of the (CoO) n.Al ₂ O ₃ green pigment particles is surrounded by the curves a and b in FIG. 1 when the reflectance of the barium sulfate powder is 100%. The pigmented green-emitting phosphor according to claim (1), which is within the region. 4. The pigment-containing green light-emitting phosphor according to claim 1, wherein the amount of the green pigment particles attached is in the range of 0.01 to 3% by weight based on the green light-emitting phosphor. 5. A matrix of a green-emitting phosphor is zinc sulfide (ZnS).
S) and contains at least one of copper (Cu) and gold (Au) as an activator, and aluminum (Al), chlorine (Cl), fluorine (F), bromine (as a co-activator). The pigment-containing green light-emitting phosphor according to claim (1), which contains at least one of Br) and iodine (I). 6. A matrix of a green light emitting phosphor is a zinc cadmium sulfide [(Zn, Cd) S] phosphor, and contains at least one of Cu, Ag and Au as an activator,
The pigmented green light-emitting phosphor according to claim (1), which contains at least one of Al, Cl, F, Br, and I as a coactivator. 7. A green light emitting phosphor is Zn ₂ SiO ₄ : M.
n, Zn ₂ SiO ₄ : Mn, As, ZnO: Zn. The pigmented green light-emitting phosphor according to claim (1). 8. The green-emitting phosphor is Ln ₂ O ₂ S: Tb,
Y ₃ Al ₂ (AlO ₄ ) ₃ : Tb, Y ₂ SiO ₅ : Tb
The green light-emitting phosphor with a pigment according to claim (1), which is any of the above. (However, Ln is at least one of Y, La, and Gd)