JPH0456869B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to phosphor slurries containing phosphate phosphors. More specifically, it relates to a phosphor slurry made of a phosphate phosphor by adding a specific amount of a specific additive to the phosphor slurry to stabilize the phosphor and prevent a decrease in brightness. .

Phosphate phosphors (hereinafter simply or abbreviated as phosphate phosphors when necessary), which are mainly composed of orthophosphates of divalent metals containing zinc, emit high-intensity red light when excited by electron beams. and is usually used in phosphors for cathode ray tubes. In addition, this phosphor has a long 10% afterglow time (the time required for the luminance to drop to 10% after excitation stops), so it is particularly useful for computer terminal displays among cathode ray tubes. It is widely used in display cathode ray tubes that have a slower scanning speed than color television cathode ray tubes, such as display devices for equipment and aircraft control systems.

This type of phosphate phosphor has, for example, a compositional formula of
Zn ₃ (PO ₄ ) ₂ : The basic composition is a phosphate phosphor represented by Mn, and it is manufactured using known technology (for example,
No. 56-121258, which was proposed earlier by the present applicant.
No., JP-A-56-136873, JP-A-57-87487,
As shown in Japanese Patent Application Laid-Open No. 58-40380, a part of the parent substance is substituted, or other activators and additives are included in the composition. however,
These phosphate phosphors have poor chemical stability, and when suspended in an aqueous ammonium dichromate polyvinyl alcohol solution, for example, the phosphor slurry changes over time due to deterioration of the phosphor. be observed.

In other words, as time passes after the slurry is prepared, the pH of the slurry decreases and shifts from neutral to weakly acidic.As a result, the viscosity of the slurry gradually increases over time, and the fluidity of the slurry decreases. It loses its properties and eventually becomes semi-solid. Therefore, various problems occur in the coating process. for example,
Not only is it difficult to control the film thickness and correction is required due to changes in exposure and development conditions over time, but if the slurry is left for a long time, coating and exposure and development of the coating film become impossible. This has caused problems such as uneven coating and even unusability. In addition, as time passes after preparing the slurry, the phosphate phosphor hydrolyzes and becomes a non-luminescent hydrated salt starting from the surface of the phosphor. There was also the problem of a decrease in

In order to avoid this problem, various measures have been taken to prevent the water from remaining wet for a long time during the post-baking process during phosphor manufacturing and during the cathode ray tube phosphor film production process, but these techniques require special processing methods. requires
This could not be said to be desirable not only technically but also economically. It has also been proposed to solve the above problem by adding a specific surfactant. (Unexamined Japanese Patent Publication No. 57-212285) However,
When the amount of surfactant used increases, the amount of residual carbon in the resulting fluorescent film (after firing) increases, leading to a problem of lowering the brightness of the fluorescent film. Further, for this reason, there was a problem that sufficient effects could not be expected even if the amount used was reduced.

Therefore, it is an object of the present invention to contain a stable phosphate phosphor that does not significantly change the viscosity of the phosphor slurry due to hydrolysis or the like and does not cause a decrease in the brightness of the phosphor and the resulting phosphor film. An object of the present invention is to provide a phosphor slurry.

In order to achieve the above object, the present inventors have conducted extensive research on phosphor slurries containing phosphate phosphors, and as a result, the inventors have found that a specific amount of at least one of magnesium, strontium and barium compounds has been added to the phosphor slurry. The present invention was completed based on the discovery that the above object can be achieved by including it in the light slurry.

The phosphor slurry of the present invention is characterized in that it contains a phosphate phosphor and at least one of oxides or hydroxides of magnesium, strontium, and barium in an amount of 0.01 to 2% by weight based on the phosphate phosphor. It is something to do.

The present invention will be explained in detail below.

The phosphor slurry of the present invention is obtained by dispersing (dissolving) in an aqueous solution a compound containing a phosphate phosphor and a specific amount of at least one of the oxides or hydroxides of magnesium, strontium, and barium. Used to obtain fluorescent coatings for tubes, etc. Therefore, when a fluorescent film is formed by exposure to light, the phosphor slurry of the present invention further contains a photosensitive resin such as polyvinyl alcohol or dichromate in the slurry; When a fluorescent film is prepared using the above-mentioned slurry, a binder such as water glass is further included in the slurry. Further, a small amount of surfactant is added to this if necessary.

In the method for producing a phosphor slurry of the present invention, when the phosphor is mixed into the slurry, a compound containing a specific amount of at least one of the oxides or hydroxides of magnesium, strontium, and barium may be added at the same time. Alternatively, it can be obtained by producing a phosphor with a compound containing at least one of the above oxides or hydroxides attached to the surface of the phosphor, and adding this phosphor to a slurry. .

FIG. 1 shows the change in pH of the phosphor slurry of the present invention thus obtained with respect to time. 1st
Curve a in the figure is the phosphor slurry of the present invention, and curve b is a conventional phosphor slurry that does not contain any oxides or hydroxides of magnesium, strontium, and barium. As is clear from Figure 1, the PH of the conventional phosphor slurry changes to acidic over time, whereas the slurry of the present invention slightly changes the PH, but goes beyond the neutral range. It is stable and does not fall off.

Moreover, the change in slurry viscosity at this time is shown in FIG. Curve a in FIG. 2 is the phosphor slurry of the present invention, and curve b is the conventional phosphor slurry. As is clear from FIG. 2, the viscosity of the conventional phosphor slurry changes significantly over time and cannot be put to practical use, but the slurry of the present invention shows almost no change in viscosity. Therefore, the phosphor slurry of the present invention significantly improves coating unevenness caused by viscosity changes during coating, which has been a problem in the past, and since the surface of the phosphor is difficult to decompose, the brightness of the phosphor can be improved. There is almost no deterioration.

Figure 3 shows the phosphor slurry containing at least one of the oxides or hydroxides of magnesium, strontium, and barium, and the content and aging of the phosphor slurry for 100 hours (during the coating process). Similarly, it is a diagram showing the relationship between the slurry viscosity (Cp) and the time it takes to put it in a mill and rotate it, where curve 1 shows the case of strontium oxide and curve 2 shows the case of barium oxide.

As is clear from Figure 3, the above content, which has the effect of lowering the slurry viscosity,
It is in the range of 0.01 to 10.0% by weight per 100 parts by weight.
However, if the above content is increased, there are problems such as a decrease in the brightness of the fluorescent film and a decrease in exposure sensitivity when exposed in the process of manufacturing the fluorescent film, so the range that can be used practically is 0.01 ~2.0% by weight. In the present invention, the above content is from 0.05 to
A range of 1.0% by weight is more preferred, and strontium oxides or hydroxides exhibit particularly good effects.

In addition, in the present invention, when a smaller amount of surfactant is used in combination, the effect is significantly improved. The surfactant used here is an anionic surfactant, such as a combination with a formalin condensate of naphthalenesulfone hydrochloric acid, etc., is recommended. By using a surfactant in combination, the content of the present invention exhibits a remarkable effect even at a small amount (0.01 to 1.0% by weight), and the surfactant used at this time has a concentration of 0.05% by weight with respect to the phosphor. -0.5% by weight, preferably 0.05-0.2% by weight, and the amount used may be small.

By using both in combination in this way, a more stable phosphor slurry can be obtained, and since at least one of the oxides or hydroxides of magnesium, strontium, and barium and the surfactant used are small, A good fluorescent film can be obtained since there is little decrease in brightness or exposure sensitivity and there is little residual carbon.

The phosphate phosphor of the present invention that can provide a good high-brightness fluorescent film by containing oxides or hydroxides of magnesium, strontium, and barium is a phosphate phosphor having the above compositional formula. It also includes conventionally well-known phosphate phosphors containing other alkaline earth metals or rare earth metals, as well as halogens and the like.

Next, the present invention will be explained with reference to Examples.

Example 1 Zn ₃ (PO ₄ ) ₂ : After adding 0.1 g of strontium oxide per 100 g of Mn phosphor and mixing thoroughly, the mixture was poured into an aqueous solution containing polyvinyl alcohol and ammonium dichromate, which are necessary for television cathode ray tubes. Then, a phosphor slurry was prepared. This phosphor slurry, as shown by curve a in FIGS. 1 and 2, exhibited a significantly more pronounced effect than the conventional phosphor slurry (curve b). This phosphor slurry
After aging for 70 hours, a fluorescent film was prepared using a conventional method, and a good, high-luminance fluorescent film was obtained.

Example 2 Zn ₃ (PO ₄ ) ₂ : After mixing 0.25 g of strontium chloride (SrCl ₂ .6H ₂ O) per 100 g of Mn phosphor, aqueous sodium hydroxide solution was added until the pH reached 13.
Example 1 was carried out using a phosphor obtained by gradually adding Sr(OH) ₂ to the surface of the phosphor.
A phosphor slurry of the present invention was obtained in the same manner as described above. This phosphor slurry showed almost the same good effects as shown in Example 1.

Example 3 A phosphor slurry of the present invention was obtained in exactly the same manner as in Example 2, except that 0.1 g of strontium nitrate was used instead of 0.25 g of strontium chloride (SrCl ₂ .6H ₂ O). This phosphor slurry exhibited good effects similar to those shown in Example 1.

Example 4 A phosphor slurry of the present invention was obtained in exactly the same manner as in Example 1 except that 0.5 g of barium oxide was used instead of 0.1 g of strontium oxide. Viscosity and pH after aging this phosphor slurry for 70 hours
The phosphor film did not change much from when the slurry was prepared, and the phosphor film obtained using this phosphor slurry had high brightness and was uniform.

Example 5 Zn ₃ (PO ₄ ) ₂ : After adding 0.03 g of strontium oxide per 100 g of Mn phosphor and mixing thoroughly, this was mixed with polyvinyl alcohol, ammonium dichromate, and anionic naphthalene sulfonate as a surfactant. 0.1g of formalin condensate (the above phosphor)
(per 100g) to create a phosphor slurry. This phosphor slurry was prepared in Example 1.
showed similar effects.

As described above, the phosphor slurry of the present invention exhibits extremely good stability compared to conventional phosphor slurries, and the obtained phosphor film is also uniform and has high brightness, so it is suitable for industrial implementation. , showing extremely remarkable effects.

[Brief explanation of drawings]

FIG. 1 is a graph showing the change in pH of the phosphor slurry of the present invention (curve a) and the conventional phosphor slurry (curve b) over time, and FIG. 2 is a graph showing the change in slurry viscosity of the slurry over time. , FIG. 3 is a graph showing the relationship between the contents of strontium oxide and barium oxide in the phosphor slurry of the present invention and the viscosity of the slurry.

Claims (1)

[Claims] 1. The phosphor slurry contains a phosphate phosphor and at least one of oxides or hydroxides of magnesium, strontium, and pallium in an amount of 0.01 to 2% by weight based on the phosphate phosphor. A fluorescent slurry characterized by: