JP2983586B2 - Undercoat agent composition for CRT aluminum back - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an undercoat agent used for forming a metal back layer using a metal such as aluminum on a phosphor screen of a CRT.

[Conventional technology]

CRTs have been used for various applications as displays, but with the diversification and high density of information in recent years, there has been a demand for even higher performance, especially high-definition displays. However, the higher the definition, the lower the luminance, and the practicality is naturally limited.

Conventionally, in order to prevent the luminance from lowering while improving the definition, a method has been conventionally used in which a phosphor layer is formed, a metal back layer using a metal such as aluminum is formed, and the reflection is used. . In this method, generally, a film is formed on the phosphor layer using an emulsion obtained by emulsifying a resin in water, and a metal back layer is formed on the film, or water is formed on the phosphor layer. Then, a resin dissolved in a solvent is applied on a water film, and a metal back layer is formed on the resin film.

[Problems to be solved by the invention]

Among the above two methods, the method of forming a metal back using an emulsion involves a large amount of volatile gas at the time of firing, and the metal back layer is lifted from the phosphor surface by the volatile gas (so-called “blistering”). Therefore, there is a limit in smoothing the metal back layer. Further, in the method of forming a metal back using a resin dissolved in a solvent, it is difficult to form a water film because the phosphor layer is water repellent,
Alternatively, in addition to the drawbacks such as the inability to maintain the smoothness of the water film, it is difficult to form a uniform layer of the solvent-based resin on the water film, resulting in unevenness of the film surface, pinholes, cracks, etc. It had many practical problems. In particular, formation of a solvent-based resin film on a water film requires smoothness of the resin film as the brightness is increased, and the larger the area, the larger the amount of gas generated. Therefore, it is necessary to reduce the film thickness, but the ratio of the area to the film thickness becomes very large, and it becomes difficult to form the film.
A composition for forming a solvent-based resin film corresponding to high definition has not been obtained.

[Means for solving the problem]

The present inventors have conducted intensive studies on the above problems,
As an undercoating agent for obtaining an aluminum back surface, suitable for high-brightness, high-definition CRT, a composition that can form a solvent-based resin film that is smooth on the phosphor screen and free of pinholes and cracks Found and arrived at the present invention.

That is, the undercoat agent for a CRT aluminum back of the present invention is methyl methacrylate, ethyl methacrylate,
Normal propyl methacrylate, isopropyl methacrylate, normal butyl methacrylate, and
A solvent containing 90 to 100% by weight of at least one alkyl methacrylate selected from isobutyl methacrylate and 1 to 7 parts by weight of an acrylic resin containing 0 to 10% by weight of an ethylenically unsaturated monomer; and a solvent 99 containing 80% by weight or more of toluene. And up to 93 parts by weight.

The alkyl methacrylate component used in the present invention is selected from those satisfying conditions such as good calcination properties and few impurities.The inside of the CRT is in a high vacuum, and is irradiated with an electron beam. It does not contain sintering residues or impurities, particularly heavy metals, halogens, etc., which pose a problem under severe conditions.

These monomers are generally polymerized by a general method, but suspension polymerization or bulk polymerization, which has a small amount of impurity residues, is recommended. In addition, since the decomposition rate of each polymer is different due to depolymerization, it is necessary to adjust the balance between the amount of gas generated during firing and the heating rate. If the amount of generated gas is too large, blistering occurs, and if the amount of generated gas is small, the firing step takes too much time and is not practical. Most preferred are polymers containing at least 70% isobutyl methacrylate.

Next, the molecular weight of the polymer is a major factor in determining the viscosity of the solution after it is made into a solution with a solvent, and determines the ease of application of the solution. The molecular weight is more preferably from 40,000 or more to 300,000 or less. If it is less than 40,000, the strength is insufficient at the time of film formation, and defects such as cracks and pinholes are likely to occur. On the other hand, if it is more than 300,000, it is difficult to balance the viscosity of the solution at the time of film formation and at the time of drying. The preferable range is 150,000 to 300,000, and the undercoat film having a small number of pinholes and having a thickness of 3 μm or less can have sufficient strength to withstand post-processes such as aluminum vapor deposition.

Further, the solvent is a water film already applied to the phosphor layer,
An organic solvent having no affinity is desirable, and an organic solvent containing 80% by weight or more of toluene is particularly preferable. Solvents determine the drying speed during coating and have a significant effect on film formation.
To form a solvent-based resin film of several microns or less on a screen of inches or more, toluene is preferable.

When the viscosity of the undercoat agent is in the range of 1 to 5 centistokes, the coating condition range is wide, and it is possible to apply evenly from a small tube of several inches to a large tube of 30 inches or more.

The optimal range of the resin concentration in the solution varies depending on the molecular weight of the resin and the coating conditions, but it is sufficient if it is 1% or more and 7% or less. In addition, unevenness and scratches occur on the aluminum deposition film.
On the other hand, if it is 7% or more, the film thickness becomes too large, the amount of generated gas also increases, blistering occurs, and the solution viscosity is high, so that the film becomes uneven.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to Examples. In addition,% and part in an Example show a weight% and a weight part, respectively.

Example 1 Production of Acrylic Resin 800 parts of water was charged into a 5 liter four-necked flask, and 1 part of polyvinyl alcohol (a degree of saponification of 88% and a degree of polymerization of 1000) was dissolved. A monomer solution obtained by dissolving 2.0 parts of azobisisobutyronitrile in 100 parts of isobutyl methacrylate is charged into a flask, and after being purged with nitrogen gas, heated to 80 ° C. with vigorous stirring under a nitrogen gas stream. . 2
After an hour, raise the temperature to 90 ° C. and heat for a further 2 hours. Then, the mixture is heated to 120 ° C., and the remaining monomer is distilled off together with water. The resulting slurry was filtered, washed, and dried with a hot air dryer at 50 ° C. to obtain an acrylic resin (sample name A) as white granular powder. The polymerization rate was 98% and the molecular weight was 100,000.

Evaluation of Undercoating Agent Using toluene as a solvent, an undercoating agent in which 6 parts of acrylic resin A was dissolved in 100 parts of solvent was spray-coated on the fluorescent screen of a 29-inch cathode ray tube which had been previously treated with a water film.
After the solvent and water were dried, aluminum was deposited and baked to obtain a color CRT. There was no luminance unevenness.

 Table 2 shows the results.

Examples 2 to 4 In the same manner as in Example 1, acrylic resins (sample names B, C, and D) shown in Table 1 were polymerized, and the undercoat agent was evaluated.

 Table 2 shows the results.

Comparative Example 1 An aluminum coating was performed by adjusting the undercoat agent in the same manner as in Example 1 except that the acrylic resin of Sample E was used as the resin for the undercoat agent, and evaluated.

As a result, there were many irregularities in the undercoat film, and there were many residues even after firing, and the function as a CRT could not be satisfied. Table 2 shows the evaluation results.

Comparative Example 2 The composition of the undercoat agent was changed to an acrylic resin (sample B).
A color CRT was obtained in the same manner as in Example 1, except that 5 parts, 30 parts of ethyl acetate, 40 parts of methyl ethyl ketone, and 30 parts of toluene were used. The undercoat layer had many irregularities and low luminance.

 Table 2 shows the results.

Comparative Example 3 The composition of the undercoat agent was changed to an acrylic resin (sample C).
A color CRT was obtained in the same manner as in Example 1 except that 12 parts, 90 parts of toluene and 10 parts of ethyl acetate were used. There were floating aluminum (blisters) at the four corners of the effective screen, and the entire screen was uneven and the brightness was low.

 Table 2 shows the results.

Comparative Example 4 A film was formed on the phosphor surface using an emulsion (trade name: Primal B-74, manufactured by Nippon Acrylic Co., Ltd.) as an undercoat agent, and after drying, aluminum deposition was performed. After forming a color cathode ray tube, the luminance was measured. However, under the same conditions as in Example 1, blisters occurred during firing, so that firing required five times the time of Example 1.

 Table 2 shows the results.

[Effects of the Invention] As demonstrated by the results of the examples, the composition of the present invention satisfies the technical requirements for CRTs of high brightness and high definition, and uses the composition of the present invention. By doing
Higher brightness than conventional emulsions, higher workability, higher productivity and higher brightness CR
You can get T.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shuichiro Tokuda 4-1-160 Sunadabashi, Higashi-ku, Nagoya City, Aichi Prefecture Inside Mitsubishi Rayon Co., Ltd. Product Development Research Center (72) Inventor Masanori Itakura 4-1-1 Sunadabashi, Higashi-ku, Nagoya City, Aichi Prefecture No. 60 Examiner, Mitsubishi Rayon Co., Ltd. Product Development Laboratory Shinichi Omori (56) References JP-A-58-14444 (JP, A) JP-A-51-71837 (JP, A) JP-A-54-27355 (JP) , A) JP 47-48263 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01J 9/22

Claims (1)

(57) [Claims] 1. A method selected from methyl methacrylate, ethyl methacrylate, normal propyl methacrylate, isopropyl methacrylate, normal butyl methacrylate and isobutyl methacrylate.
90 to 100% by weight of at least one alkyl methacrylate, 1 to 7 parts by weight of an acrylic resin composed of 0 to 10% by weight of an ethylenically unsaturated monomer, and 99 to 93 parts by weight of a solvent containing 80% by weight or more of toluene. CRT characterized by the following:
Undercoat agent for aluminum back.