JPS5931053B2 - Kankoseisoseibutsu - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photosensitive composition containing polyvinyl alcohol (hereinafter referred to as PVA) as a main component, that is, a so-called phosphor slurry, and particularly to specifying a solvent in the phosphor slurry. Therefore, it has already been formed.

The purpose of this invention is to enable a plurality of colors of fluorescent films to be applied separately without deteriorating the film retention of the underlying exposed coating film, that is, the fluorescent film. At the same time, it is intended to improve various properties of the phosphor slurry, such as defoaming effect, lower viscosity, and quick drying properties.
In an electronic tube such as a color television picture tube or a color fluorescent display tube, each color of phosphor, for example, red, green, and blue phosphors, has a color phosphor surface painted in a predetermined pattern. .

Usually, to form this color fluorescent surface, a phosphor slurry of each color is used, which is obtained by kneading PVA as a photocurable binder and phosphor powder of each color with a solvent. First, a phosphor slurry of one color is applied to the inner surface of a substrate on which a phosphor surface is to be formed, such as a picture tube panel, and then exposed to light in a predetermined pattern. The fluorescent film of the first color is formed by washing and removing the film. Next, after coating the entire surface including the first color fluorescent film with a second color phosphor slurry, the same process is repeated to form a second color fluorescent film, and the same method is used thereafter. Then, a third color fluorescent film is formed. by the way.

As a solvent in a phosphor slurry containing PVA as a main component, water or a solvent containing water as a main component and a slight amount of alcohol has generally been used. However, in the case of a phosphor slurry using water or water containing a small amount of alcohol as a solvent, when coating multiple colors of fluorescing films as described above, it is difficult to use the phosphor of the second color. When the body slurry or the third color phosphor slurry is coated on the entire surface, the first color phosphor film or the second color phosphor film that has already been formed is oxidized by the solvent in the phosphor slurry. There was a risk that the coating would be partially dissolved and the film retention of the lower layer fluorescent film would be deteriorated. In particular, this phenomenon is related to low molecular weight PV, which the applicant previously developed in order to increase the packing density of the phosphor and obtain a phosphor film with high luminance.
This was noticeable in the phosphor slurry containing A as the main component. This means that the water solubility of low molecular weight PVA is higher than that of high molecular weight PVA.
This is because it is larger than A and has a wide molecular weight distribution even when it is a single PVA, so when it is exposed, the molecular weight of PVA in the exposed area does not disintegrate and the exposed area with low molecular components is applied next. It was dissolved by the solvent (water) of the phosphor slurry. In order to facilitate understanding of the present invention, a phosphor slurry mainly composed of low molecular weight PVA as previously proposed will be described.

This phosphor slurry has an average molecular weight of 10,000 to 500.
00 so-called low molecular weight PVA and 4 to 10 of this PVA
It has double the amount (weight) of phosphor and is dissolved in a solvent so that the solid content is 30% (weight) or more. Examples of PVA having an average molecular weight Xr of 10,000 to 50,000 include Denkapoval B-05 and Gohsenol GL-05.
, Kuraray PVA2O5 (both are trade names and the average price is about 20,000), etc. can be used. Incidentally, PVA used in conventional phosphor slurry has an Mn of 60,000 or more. In the above phosphor slurry, 10,000 to 50
000 PVA is specified because if the M number is less than 10,000, it will lose its properties as a polymer and its function as a binder will be insufficient, and if the M number exceeds 50,000, it is expected that the packing density of the phosphor will improve. This is because it becomes impossible to do so. In addition, the reason why the amount of phosphor is selected to be 4 to 10 times the weight of PVA is that if the amount is less than 4 times, the packing density of the phosphor cannot be expected to improve, and if the amount exceeds 10 times, the amount of phosphor particles will be reduced. This is because the voids cannot be sufficiently filled with the binder, ie, PVA, and the strength of the coating film itself decreases. This phosphor and P
Most preferably, the ratio of VA is selected to be approximately 7:1 (by weight). Furthermore, the solid content in the slurry, i.e. mainly P
The reason why the sum (weight) of each content of VA and phosphor is selected to be 30% or more is because if it is less than 30%, no improvement in the packing density of the phosphor can be expected. According to the phosphor slurry using such low molecular weight PVA, a high phosphor packing density can be obtained with a small film thickness, so that a phosphor film with high luminance can be formed. On the other hand, when using a phosphor slurry, it is desired that even if foaming occurs when it is applied, the foam disappears within a short period of time, that is, it has a good defoaming effect.

When these bubbles form a phosphor film, they create pinholes, resulting in a decrease in the packing density of the phosphor and a decrease in luminance. or,
In a phosphor slurry, a low viscosity is desired because the lower the viscosity of the phosphor slurry, the higher the packing density of the phosphor. Furthermore, it is desirable that the phosphor slurry has excellent quick drying properties, since workability can be expected to improve if the coating film dries quickly after being applied. In view of the above-mentioned points, the present invention provides a photosensitive composition containing PVA as a main component, that is, a phosphor sumuri, which reduces the film retention of the exposed coating film of the lower layer, that is, the fluorescent film that has already been formed. The object of the present invention is to provide a phosphor slurry that can form a good phosphor film without causing deterioration.

Furthermore, the present invention provides a phosphor slurry with excellent defoaming effect, low viscosity, quick drying property, etc. In the present invention, a photosensitive composition containing PVA as a main component, that is, a phosphor slurry In the phosphor slurry, a solvent consisting of water as the main component and a predetermined amount of volatile non-solvent is used as the solvent in the phosphor slurry. It is a so-called non-solvent for PVA, and the amount of this non-solvent added is such that it dissolves the largest molecular weight component of PVA within a practical range, and
The amount of the non-solvent to be added is selected to be an amount that does not deteriorate the film retention of the already formed lower layer fluorescent film within a practical range.The amount of the non-solvent to be added varies depending on the molecular weight of PVA as the main component.

As a non-solvent, it is compatible with water and has a solubility parameter (
cohesive energy density) δ is as small as possible, that is, δ
= 8 to 20, and is preferably volatile. Here, the solubility parameter δ was specified to be in the range of 8 to 20 as the non-solvent condition because δ was 8.
If δ is less than 20, it will not dissolve in water, and if δ exceeds 20, it will approach the solubility parameter of water, and the effect of lowering the solubility in the underlying fluorescent film cannot be expected. Furthermore, the reason why a non-solvent with good volatility was selected is that the coating film of the phosphor slurry dries quickly and workability can be improved.

The table below lists some of the volatile nonsolvents applicable to the present invention and shows the solubility parameter δ of each nonsolvent in comparison with water.

In the present invention, one or more nonsolvents as shown in the table above are mixed with water to form a solvent for a phosphor slurry containing PVA as a main component.

Next, we will discuss the film retention, antifoaming properties, viscosity, etc. of the phosphor slurry using a solvent made by dissolving the above non-solvent in water. Figure 1 shows the non-solvents listed in the table above. In a PVA photosensitive liquid (in this example, a PVA photosensitive liquid with an average molecular weight Mn of about 20,000) dissolved in a solvent made by mixing acetone, tetrahydrone furan, dimethylformamide, isopropyl alcohol, and methanol with water. , the film retention properties of the exposed and unexposed coatings when the volume fraction of each non-solvent was changed, that is, the PVA photosensitive solution was applied to the entire surface including the already formed exposed coating film in a predetermined pattern. FIG. 2 is a relationship diagram showing the film retention of the lower exposed coating film and the solubility of the unexposed portion of the PVA photosensitive film in a fixing solution when exposed and fixed (developed).

In the figure, the vertical axis shows the coating film residual rate, and the horizontal axis shows the volume fraction of each nonsolvent. The solid line shows the residual characteristics of the lower exposed coating film due to the solvent in the PVA photosensitive solution when the PVA photosensitive solution is applied. Curve a1 shows the lower limit when acetone is used, and curve A5 shows the lower limit when using each of the other non-solvents. show. Also, the dotted line is PVA
The residual characteristics of the unexposed area when a photosensitive liquid is applied, exposed and fixed in a predetermined pattern, curve B1 is when acetone is used, curve B2 is when tetrahydrofuran is used, and curve B3 is when dimethylformamide is used. , curve B4
Curve B5 is the case when isopropyl alcohol is used, and curve B5 is the case when methanol is used. As is clear from FIG. 1, for example, in the case of a solvent containing 100% water, the coating residual rate of the lower exposed coating film is as low as about 45%, making it inappropriate to use water as a solvent for PVA photosensitive liquids. However, in the case of a solvent in which a non-solvent is mixed with water, the coating film residual rate of the lower exposed coating film increases as the non-solvent increases, making it suitable as a solvent for PVA photosensitive solutions. In addition, in the case of the remaining coating film in the unexposed area, for example, in the case of acetone, its volume fraction is O until about 25%, and beyond this point, an insoluble area appears (see curve B). Therefore, for example, when acetone is used as a solvent for a photosensitive composition mainly composed of PVA with an average molecular weight of 20,000, it is prepared by mixing water with a practical range of acetone at around 25% volume or less. The composition is preferred. Although not shown in the figure, as the average molecular weight of PVA changes, that is, as the average molecular weight decreases, the curve b1 shifts to the right side of the figure, and the practical range of acetone as a solvent falls within the above 25.
It tends to expand more than the volume %. In addition, solvents using various non-solvents other than acetone also improve the retention of the lower exposed coating film, and among them, the solvent using acetone (curves Al and bl) was found to be the most effective. It will be done. It is desirable for the solvent used in the present invention to have as little non-solvent content as possible in view of manufacturing costs, etc. However, as shown in the results in Figure 1, there are exceptions as the amount of non-solvent can be reduced. However, in general, the smaller the solubility parameter δ value of a nonsolvent, the higher the coating film retention rate of the lower exposed coating film tends to be. Figure 2 shows the relationship between the time for the bubbles to disappear and the volume fraction of acetone when the PVA photosensitive liquid is bubbled in a PVA photosensitive liquid in which 5% by weight of PVA is dissolved in a solvent made of a mixture of water and acetone. FIG.

According to Figure 2, a small amount of acetone is mixed with water as a solvent? It is observed that the bubble disappearance time in the PVA photosensitive solution decreases rapidly even when the PVA photosensitive solution is used. Therefore, the phosphor slurry according to the present invention has an excellent antifoaming effect, and when a phosphor film is formed, pinholes are not formed and the phosphor packing density is increased.
Emission brightness can be further improved. Figure 3 shows water and water.
S, :,': Number 2, 2 = = is a characteristic curve diagram showing the relationship between the volume fraction of acetone and the viscosity of the PVA photosensitive liquid.

From this figure 3, is it possible to use a mixture of water and acetone as a solvent or to use a solvent that is 100% water? It is recognized that the viscosity of the PVA photosensitive liquid is greatly reduced compared to the case of PVA.
It is related to the ratio of the amount of phosphor to the amount of phosphor, that is, the ratio of phosphor/PVA.If the viscosity is low, this ratio can be increased, and the amount of phosphor can be increased accordingly, and as a result, The viscosity of the phosphor slurry that improves the luminance is P
When the ratio of VA to solvent (PVA/solvent) is constant, P
It also decreases by lowering the average molecular weight Mn of VA. Therefore, if the average molecular weight Mπ of PVA is constant, and P
When the VA/solvent ratio is kept constant, if a solution made by mixing water and a non-solvent such as acetone is used as a solvent for a phosphor slurry mainly composed of PVA, the viscosity of the phosphor slurry will decrease. is lower than that of the conventional one, and therefore the phosphor/P
The VA ratio can be increased, and a phosphor slurry with a higher phosphor packing density can be obtained. Figures 2 and 3 show the case where acetone is used as a non-solvent in the solvent.
A similar tendency is observed when other non-solvents shown in the above table are used.Next, examples of the phosphor slurry of the present invention will be shown.

When applied to the formation of a color fluorescent film, the phosphor slurries with the compositions shown in Examples and 0 are used to form a first color fluorescent film that has already been formed, or A good color fluorescent film is formed without degrading the second color fluorescent film.

In addition, the antifoaming effect is good, and by lowering the viscosity, the packing density of the phosphor is improved, and the luminance of light emission is improved. Furthermore, after applying the phosphor slurry, it dries quickly and improves workability. As a fixing solution for the fluorescent film using the low molecular weight PVA phosphor slurry shown in the above example, a solvent having the same composition as the solvent described in the present invention can be used. Although applied to a PVA phosphor, it can also be used for a high molecular weight PVA phosphor slurry.

However, the effects of the present invention are more pronounced when low molecular weight PVA is used than when high molecular weight PVA is used. As mentioned above, by using the phosphor slurry of the present invention, multiple colors of phosphors can be coated separately without deteriorating the film retention of the lower layer phosphor film, and furthermore, the phosphor slurry of the present invention can be applied with different colors. It has excellent effectiveness, low viscosity, and quick drying properties, and its application to color television picture tubes has tremendous benefits.

[Brief explanation of drawings]

Figure 1 shows the film retention properties of exposed and unexposed coatings when the volume fraction of the nonsolvent is changed in a PVA photosensitive solution using a solvent consisting of water and various volatile nonsolvents. The characteristic curve diagram shown in Figure 2 is PVA using a solvent consisting of water and acetone.
P when changing the volume fraction of acetone in the photosensitive solution
Figure 3, a characteristic curve diagram showing the defoaming effect of VA photosensitive liquid, shows the viscosity of PVA photosensitive liquid when the volume fraction of acetone is changed in a PVA photosensitive liquid using a solvent consisting of water and acetone. FIG.

Claims (1)

[Claims] 1. In a photosensitive composition containing polyvinyl alcohol as a main component, the solvent in the photosensitive composition dissolves the maximum molecular weight component of the polyvinyl alcohol within a practical range, and dissolves the exposed coating film of the lower layer within a practical range. 1. A photosensitive composition characterized by using a solvent obtained by dissolving in water an amount of a volatile non-solvent that does not cause deterioration.