JPH07777B2 - Fluorescent paste composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a phosphor paste composition for forming a phosphor layer in a fluorescent display device.

[Conventional technology]

Conventionally, in order to form a fluorescent surface in a fluorescent display device, a fluorescent paste composition is prepared by kneading a vehicle consisting of fluorescent powder, an organic polymer binder and a solvent to form a fluorescent surface. Screen printing the phosphor paste composition in a desired pattern on the substrate to be, after removing the solvent by drying, the phosphor layer by pyrolytically removing the organic polymer binder by firing. Had formed.

As the vehicle used in the conventional fluorescent paste, an acrylic resin or a cellulose derivative is used as an organic polymer binder, which is used in an organic solvent such as ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, and terpineol. The one that was melted was used.

[Problems to be Solved by the Invention] However, in the conventional phosphor paste composition, when the organic polymer binder is thermally decomposed during firing, it adversely affects the phosphor, and the surface of the phosphor deteriorates. However, the luminescent properties of the phosphor are remarkably deteriorated, so that the desired luminance cannot be obtained, or the color when emitting light becomes cloudy, so that the desired luminescent color cannot be obtained.

Further, when a phosphor layer that emits a reddish color is formed by a conventional phosphor paste composition, a desired color is emitted if the film thickness is 30 μm or more, but if the film thickness is thinner than that, It does not emit light of a desired color, and when the film thickness is 15 μm or less, it does not emit light at all. This is because the phosphor density per unit area is low, and it is well known that if the phosphor density per unit area is increased, the emission characteristics are improved, so if the phosphor layer is higher than the conventional phosphor layer. If it is possible to form a fluorescent layer having a high optical density, it is possible to obtain the same emission brightness as that of the conventional one with less power consumption than the conventional one. However, there has been no phosphor paste composition capable of forming such a phosphor layer.

[Means for Solving the Problems]

The present inventor has conducted extensive studies in order to solve such problems, and as a result, blends an ethylenically unsaturated compound in a vehicle and utilizes shrinkage during thermal polymerization of this particular ethylenically unsaturated compound. The present invention has been completed based on the finding that the fluorescent substance density can be increased by packing the fluorescent substance particles.

That is, at least one organic polymer bond selected from the group consisting of ethylenically unsaturated compounds having two or more acryloyl groups or methacryloyl groups, which are polymerized by heating, cellulose ethers, cellulose esters, and acrylic copolymers is used. Fluorescent substance obtained by kneading a fluorescent substance powder with a vehicle composed of one or more kinds of organic solvents selected from the following substances and glycol ethers, glycol esters, glycol ether esters, ketones, ketone alcohols and alkoxy esters. A body paste composition is provided.

The ethylenically unsaturated compound having two or more acryloyl groups or methacryloyl groups which is polymerized by heating in the present invention preferably has a volume that shrinks after thermal polymerization. It is not preferable to use an ethylenically unsaturated compound having a small volume shrinkage ratio after the thermal polymerization as compared with that before the thermal polymerization because a sufficient phosphor density cannot be obtained. Further, it is not preferable to use an ethylenically unsaturated compound having a too high shrinkage rate, because the dimensional accuracy of the pattern after firing will be deteriorated. As an approximate guide, it is preferable to use an ethylenically unsaturated compound having a volumetric shrinkage ratio of 5 to 20% after thermal polymerization with respect to before thermal polymerization.

Specifically as such an ethylenically unsaturated compound,
Polyethylene glycol diacrylates and dimethacrylates such as diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, polyalkylene glycol diacrylates, poly Alkylene glycol dimethacrylates, hentaerythritol triacrylate, pentaerythritol trimethacrylate, pentaerythritol diacrylate, pentaerythritol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, 2,2-dimethylpropanediacrylate, 2,2 -Zimechi And the like propane dimethacrylate, but it is not limited thereto. These may be used alone or in combination of two or more.

One or more organic polymer binders selected from the cellulose ethers, cellulose esters and acrylic copolymers used in the present invention are those used in conventional phosphor paste compositions, such as methyl cellulose and ethyl cellulose. , Hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, and other cellulose ethers, cellulose acetate and other cellulose esters, and acrylic copolymers.

The organic polymer engaging material used in the present invention has a molecular weight of 10,000.
~ 2,000,000, preferably in the range of 80,000 to 1,000,000 is used. When the molecular weight is less than 10,000, the adhesion to the substrate decreases and the phosphor powder retaining property decreases, which is not preferable. If the molecular weight exceeds 2,000,000, it becomes difficult to decompose and evaporate the organic polymer bound material during firing.

In the present invention, the phosphor paste composition is patterned using a screen printing method on a substrate. When patterning using a screen printing method, it is not preferable to use a solvent having a high evaporation rate such as water because the screen mesh will be clogged. Therefore, in the present invention, it is preferable to use an organic solvent that has good compatibility with the ethylenically unsaturated compound and the organic polymer conjugate and has a slower evaporation rate than water and the like.

The organic solvent of the present invention is diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monoethyl ether. Butyl ether acetate, propylene glycol monobutyl ether, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, methoxybutyl acetate, diacetone alcohol, isophorone diisobutyl ketone, terpineol, etc. Yes, these can be used alone, or two
Used in combination of two or more species.

The phosphor powder used in the present invention is ZnO: Zn, (Zn: C
d) S: Ag, ZnS (Cu, Al), ZnS: Ag, Y ₂ O ₂ S: Eu, ZnS: Zn, etc. which have been conventionally known can be used.

In the present invention, if desired, a photopolymerization initiator for photopolymerizing the ethylenically unsaturated compound may be added. By incorporating a photopolymerization initiator, patterning can be performed by photolithography instead of the screen printing method. As such a photopolymerization initiator, a generally known one can be used. For example, anthraquinones such as ethylanthraquinone, benzanthraquinone and diaminoanthraquinone,
Benzophenone, benzophenones such as 4,4′-bis (dimethylamino) benzophenone, isobutyl benzoin ether, isopropyl benzoin ether, benzoin ethyl ether, benzoin ethers such as benzoin methyl ether, 2,4-diethylthioxanthone,
Thioxanthones such as 2-chlorothioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, and 2-methylthioxanthone, 2,2-dimethoxy-2
-Phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 1,1-cycloloacetophenone,
2-Methyl-1- [4- (methylthio) phenyl] -2
-There are acetophenones such as morpholino-1-propanone. These may be used alone or in combination of two or more.

The blending ratio of each component in the present invention is the organic polymer conjugate
With respect to 100 parts by weight, the ethylenically unsaturated compound is preferably in the range of 30 to 200 parts by weight, and when a photopolymerization initiator is added,
The range of 0.01 to 25 parts by weight is preferable. If the blending ratio of the ethylenically unsaturated compound is less than 30 parts by weight, the effect of the present invention cannot be obtained, and if it exceeds 200 parts by weight, sticking tends to occur, which is not preferable.

In the present invention, the viscosity of the phosphor paste composition is adjusted, and an organic solvent is added in order to obtain a viscosity suitable for the screen printing method. The phosphor paste composition of the present invention is 100
It is preferably used with a viscosity in the range of to 3000 p, particularly preferably in the range of 500 to 2000 p. The mixing ratio of the organic solvent at this time is in the range of 100 to 2000 parts by weight based on 100 parts by weight of the total amount of the organic polymer binder and the ethylenically unsaturated compound.

The mixing ratio of the phosphor powder varies depending on the kind of the phosphor powder, but as a rough guide, it should be 80 to 700 parts by weight based on 100 parts by weight of the total amount of the organic polymer binder and the ethylenically unsaturated compound. Is preferred. If the blending ratio of the phosphor powder is less than this range, sufficient strength cannot be maintained after firing, or the phosphor density is lowered, and sufficient emission brightness cannot be obtained. If the blending ratio is more than this range, it becomes difficult to hold the phosphor powder by the resin component, and the pattern formed by printing or photolithography may be collapsed before firing.

Further, additives such as thermal polymerization inhibitors such as hydroquinone, tert-butylhydroquinone, benzoquinone and catechol, dyes, pigments and defoaming agents can be added to the phosphor paste composition of the present invention as required.

Next, a method for forming a phosphor layer using the phosphor paste composition of the present invention will be described.

The phosphor paste composition of the present invention adjusted to have an appropriate viscosity is printed on the surface of the substrate by a screen printing method in a desired pattern so that the film thickness after drying is 10 to 30 μm.
Dry at -80 ° C for 15-20 minutes.

Then, the temperature is gradually raised in the firing furnace to perform firing. The ethylenically unsaturated compound undergoes thermal polymerization during heating to shrink, and is then thermally decomposed and removed together with the organic polymer binder. The firing temperature at this time varies depending on the type of phosphor powder used, but as a rough guide, the maximum temperature is 500 to 600 ° C.
It is a degree. The film thickness of the phosphor layer after firing is about 8 to 30 μm.

When forming a pattern by photolithography, a phosphor paste composition containing a photopolymerization initiator is applied to the entire surface of the substrate by a screen printing method, and after drying, a mask having a desired pattern is formed. Irradiate with actinic rays through. The exposure amount at this time is in the range of ^{20 to} 600 mJ / cm ² when using, for example, an ultrahigh pressure mercury lamp.

Next, the unexposed area is removed by development using water or an organic solvent. In the case of spray development, the development time is 40 to 90 seconds at room temperature. After the development process, dry it immediately with a dryer,
Then, firing is performed to form a patterned phosphor layer.

〔Example〕

 Examples of the present invention will be shown below and will be described in more detail.

Example 1 10 parts by weight of tetraethylene glycol diacrylate, 30 parts by weight of a copolymer of methyl methacrylate and β-hydroxyethyl acrylate (weight ratio 90:10, average molecular weight 50,000), 90 parts by weight of diethylene glycol monoethyl ether acetate, Defoamer 0.1 parts by weight, phosphor powder (ZnO: Zn) 2
71.2 parts by weight was kneaded with a three-roll mill to prepare a phosphor paste composition. The viscosity at this time was 1500 p at 25 ° C. when measured with a B-type rotational viscometer.

Next, this phosphor paste composition was printed on a glass substrate for a fluorescent display tube through a screen on which a predetermined pattern was formed so that the film thickness after drying would be 30 μm, and at 20 ° C., 20
After drying for 1 minute, it was baked at 500 ° C. for 10 minutes to obtain a phosphor layer having a desired pattern. A fluorescent display tube was created using this substrate, and the luminous flux was measured to be 9lm.
(Lumen), which is about 50% higher than that of a fluorescent display tube prepared using a conventional fluorescent paste composition.

Example 2 15 parts by weight of trimethylolpropane triacrylate and 30 parts by weight of hydroxypropyl cellulose (average molecular weight of about 100,000), 90 parts by weight of diethylene glycol monoethyl ether, 0.1 part by weight of antifoaming agent, phosphor powder ((Zn: Cd ) S: Ag) 271.
Two parts by weight were kneaded with a three-roll mill to prepare a phosphor paste composition. The viscosity at this time was 1550 p at 25 ° C. when measured with a B-type rotational viscometer.

Next, a fluorescent layer having a film thickness of 10 μm was formed in the same manner as in Example 1 to prepare a fluorescent display tube. As a result, favorable light emission was performed without discoloration.

Example 3 30 parts by weight of pentaerythritol triacrylate, 30 parts by weight of hydroxypropyl cellulose (average molecular weight 60,000), 2-methyl- [4- (methylthio) phenyl] -2
-Morpholino-1-propanone 2 parts by weight, 2,4-diethylthioxanthone 0.6 parts by weight, methylhydroquinone 0.1
5 parts by weight, antifoaming agent 0.1 parts by weight, oil blue # 603 (manufactured by Orient Chemical Co.) 0.05 parts by weight, N, N-diethylaniline
0.03 parts by weight, diethylene glycol monoethyl ether
A phosphor paste composition was prepared by kneading 100 parts by weight and 160 parts by weight of phosphor powder (ZnO: Zn) with a three-roll mill. The viscosity at this time was measured with a B-type rotational viscometer and found to be 25 ° C.
It was 850p.

Next, this phosphor paste composition was applied to the entire surface of a glass substrate for a fluorescent display tube through a 150-mesh screen, allowed to stand for 10 minutes, dried at 80 ° C. for 20 minutes, and allowed to stand at room temperature. . Then, 200 mJ / cm ² of ultraviolet rays were selectively irradiated with a 3 KW ultra-high pressure mercury lamp through a mask having a predetermined pattern, and spray development was performed with water for 1 minute. 1 at 500 ℃
Film thickness with 100 μm square dot pattern after baking for 0 minutes
When a phosphor layer having a thickness of 10 μm was formed to prepare a fluorescent display tube, the same results as in Example 1 were obtained.

Comparative Example 1 A phosphor paste having the same composition as in Example 1 except that tetraethylene glycol diacrylate was removed was prepared, and a fluorescent display tube was prepared in the same manner as in Example 1 below. Was 6 lm.

Comparative Example 2 25 parts by weight of ethyl cellulose (N-50 manufactured by Hercules Co., Ltd.), 500 parts by weight of ethylene glycol monobutyl acetate, and 780 parts by weight of phosphor powder (ZnO: Zn) were kneaded with a three-roll mill to prepare a phosphor paste composition. The thing was prepared.

Next, this phosphor paste composition was printed on a glass substrate for a fluorescent display tube through a screen having a predetermined pattern so that the film thickness after drying was 30 μm, and dried at 90 ° C. for 20 minutes. Then, it was baked at 540 ° C. for 10 minutes to obtain a phosphor layer having a desired pattern. A fluorescent display tube was prepared using this substrate, and the luminous flux was measured and found to be 6 lm.

Comparative Example 3 25 parts by weight of ethyl cellulose (N-50 manufactured by Hercules), ethylene glycol monobutyl ether acetate
A phosphor paste composition was prepared by using 500 parts by weight of phosphor powder ((Zn: Cd) S: Ag) of 780 parts by weight, and a 10 μm-thick phosphor film was prepared on a glass substrate in the same manner as in Comparative Example 2. When a phosphor layer was formed and a fluorescent display tube was prepared, a desired red emission color was not obtained.

〔The invention's effect〕

According to the present invention, since a specific ethylenically unsaturated compound is blended in the phosphor paste composition, volume shrinkage due to thermal polymerization can increase the phosphor density in the composition, and is excellent in light emission characteristics. It is possible not only to form a fluorescent layer, but also to emit a favorable light without discoloring as a thin film, so that it is possible to save power consumption.

Claims (1)

[Claims] 1. At least one organic polymer selected from ethylenically unsaturated compounds having at least two acryloyl groups or methacryloyl groups which are polymerized by heating, cellulose ethers, cellulose esters and acrylic copolymers. Conjugates and glycol ethers,
A phosphor, which is obtained by kneading a phosphor powder with a vehicle made of one or more organic solvents selected from glycol esters, glycol ether esters, ketones, ketone alcohols and alkoxy esters. Paste composition.