JPH08315730A - Undercoat resin to form metal reflecting film inside cathode ray tube - Google Patents

Abstract

PURPOSE: To prevent the flotation and separation of aluminum by increasing the range of a firing temperature, using organic resin with different firing temperature zones, and firing at a specified temperature rise speed. CONSTITUTION: Undercoat organic resin used to form a fluorescent metal reflecting film inside a cathode ray tube has a temperature difference from the beginning of firing to the end to be set 90 deg.C or more when a temperature rise speed during firing under an air atmosphere is 7 deg.C/min. As the organic resin, organic resin mainly containing acrylic resin is used from the point of firing, independently or two or more types combined. If two or more types combined, the mixture ratio of both components is selected in a preset range in consideration of preventing the flotation of the metal reflecting film. If required, various types of additives are applied to prevent the blister of the metal reflecting film during firing. Such undercoat resin to form the metal reflecting film is used to effectively prevent the flotation and separation of aluminum and keep high reflectivity with excellent smoothness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a cathode ray tube (hereinafter referred to as CR
(Referred to as T), the present invention relates to an undercoat resin used as a base for forming a metal reflective film such as aluminum after forming a phosphor layer on the inner surface of the panel.

[0002]

2. Description of the Related Art CRTs are used for various purposes as displays, but in recent years, with the diversification of information and the increase in density, higher performance and higher definition display have been required.
However, the higher the resolution of the CRT, the lower the brightness, and the practicality naturally has its limit. Therefore, in order to prevent a decrease in luminance while achieving higher definition, a method of forming a metal reflection film by depositing a metal such as aluminum after forming a phosphor layer on the inner surface of the panel and utilizing a light reflection effect Was taken.

[0003]

However, this method cannot efficiently reflect light to the front surface of the CRT because a metal reflection film having a mirror effect cannot be obtained due to the unevenness of the phosphor layer surface. Therefore, at present, a filming process is usually performed in which irregularities on the surface of the phosphor layer are covered with an organic material layer (hereinafter referred to as an undercoat film) that can be fired in advance to form a film having a smooth surface. In this method, a metal reflection film is formed by subjecting the undercoat film to a metal vapor deposition, followed by firing to decompose and remove the undercoat film.

Specific methods for forming an undercoat film are roughly classified into a method in which an emulsion in which a resin is dispersed in water is applied to the surface of a phosphor layer and dried, and a method of forming a water film on the surface of the phosphor layer, Next, there is a water film method in which a resin dissolved in a solvent is applied onto the water film and dried. Since the former emulsion method is a one-component type, it is necessary to apply a large amount of emulsion to fill the irregularities on the phosphor layer surface to form a smooth surface, so the undercoat film is removed by baking. There is a large amount of gas volatilized when doing, the metal reflective film is peeled from the phosphor layer by this volatile gas,
The so-called "blistering" phenomenon such as floating easily occurs, and there is a limit in achieving a high degree of smoothness of the metal reflective film. On the other hand, the latter water film method is a wet-on-wet method obtained by forming a water film on the phosphor layer surface and applying and drying a resin dissolved in a solvent on the water film surface, and thus the former method. The undercoat film formed has a smaller resin thickness than that of No. 1, and the amount of volatile gas when the metal is vapor-deposited on the film and then removed by firing is small. However, even with this method, in order to form a smooth metal reflection film, the water film or the undercoat film must be thickened, and as in the former emulsion method, the "blistering" phenomenon occurs in the metal reflection film. In addition, there is an essential problem that there is a limit in obtaining a smooth mirror surface of the metal reflection film necessary for improving the brightness of the CRT.

The cause of such "blistering" phenomenon is that (a) there is a shortage of volatile gas escape holes at the contact portion between the metal reflection film and the phosphor layer, and (b) thick film of the undercoat film. It has been considered that the amount of volatile gas at the time of firing increases with the increase in temperature. Therefore, in order to prevent the "blistering" phenomenon of the metal reflection film, a method of thinning the undercoat film or a method of generating a volatile gas little by little by making the firing removal time of the undercoat film extremely long is taken. Came. However, when the thickness of the undercoat film is reduced, it is not possible to sufficiently fill the irregularities on the phosphor surface, and it is not possible to form a smooth metal reflection film that can improve the brightness. Further, when the baking time of the undercoat film was made extremely long, it was possible to form a metal reflection film having smoothness capable of improving the brightness of the CRT, but the productivity is extremely lowered. Occurred.

In order to solve these problems, Japanese Patent Publication No.
JP-A-7-24416 discloses a filming solution comprising an acrylic emulsion, a poval boric acid complex, and hydrogen peroxide. This method forms cracks and pores in the undercoat film covering the phosphor layer by the action of the poval borate complex and hydrogen peroxide, and forms pores for venting the volatile gas generated during firing. This is to prevent blistering during firing. However, even in this method, in order to improve the smoothness of the undercoat film, the undercoat film may be thickened,
If the firing rate is increased to improve productivity, "blistering" occurs and it is impossible to obtain a metal reflective film having a mirror effect.

An object of the present invention is to provide a smooth metal reflection film having good productivity without roughening, peeling, blistering, etc. in order to obtain a CRT having high definition and high brightness. An object is to provide an undercoat resin that can be formed.

[0008]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have found that the temperature difference from the firing start temperature to the firing end temperature of the undercoat resin for forming a metal reflection film, that is, the firing temperature range is determined. It has been found that the above problems can be solved by widening the gas and gradually generating the decomposed gas, and the present invention has been completed.

That is, according to the present invention, an undercoat organic resin used for forming a phosphor metal reflection film on the inner surface of a cathode ray tube is
The temperature rising rate when firing in an air atmosphere is 7 ° C./min, and the temperature difference from the start of firing to the end of firing is 90 ° C. or more. Further, it has been found that it is preferable to use a mixture of organic resins having different firing temperature regions in order to obtain an undercoat resin having such a wide firing temperature range.

The present invention will be described in detail below. The undercoat resin of the present invention is 5-10 in an air atmosphere.
An organic resin having a temperature difference of 90 ° C. or more from the start of firing to the end of firing, which is fired at a temperature rising rate of ° C./min. Preferably, firing is performed in an air atmosphere at a temperature rising rate in the range of 5 to 10 ° C / minute, particularly preferably in the range of 7 to 8 ° C / minute, and the temperature difference from the start of firing to the end of firing is 100 ° C or more. Is. When the temperature difference from the start of firing of the undercoat film to the end of firing is less than 90 ° C., the metal reflection film is lifted or peeled from the phosphor surface in the firing process performed after metal deposition on the undercoat film.

Further, the present inventors have found that in order to obtain such an undercoat resin having a wide baking temperature range, it is preferable to use a mixture of organic resins having different baking temperature regions. The undercoat resin of the present invention has a firing start temperature of less than 260 ° C. and a firing end temperature of 290 ° C. or higher when fired at a temperature rising rate of 7 ° C./min in an air atmosphere.
Organic resin (A) below 60 ° C and 7 ° C / in air atmosphere
It is preferable to use an organic resin (B) having a firing start temperature of 260 ° C. or more and 300 ° C. or less and a firing end temperature of 360 ° C. or more when fired at a heating rate of a minute.

The organic resin used as the component (A) and the component (B) is preferably an organic resin containing a (meth) acrylic resin as a main component from the viewpoint of baking property. Specifically, a (meth) acrylate monomer, an acid monomer or the like may be used alone or in combination of two or more.

Specific examples thereof include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, sec-butyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate and 2-ethylhexyl methacrylate. , 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and other methacrylate monomers, methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-
Butyl acrylate, sec-butyl acrylate, t
ert-butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, benzyl acrylate, and other acrylate monomers, methacrylic acid, acrylic acid, itaconic acid, and other acid monomers, and the like. Examples thereof include polymers and / or copolymers.

These may be used alone or in combination of two or more.

When two or more kinds of monomers are used here, the firing temperature varies depending on the combination, but generally, the firing start temperature is less than 260 ° C. is the methacrylate monomer, and the firing start temperature is 260 ° C. Since the acrylate monomer, the acid monomer and the like are mentioned above, the temperature difference between the firing start temperature and the firing end temperature may be adjusted and used in consideration of these.

For example, when the firing start temperature of the component (A) is less than 260 ° C., n-butyl methacrylate,
Monomers or copolymers of monomers such as 2-ethylhexyl methacrylate, methyl methacrylate, and i-butyl methacrylate, or acrylate monomers and acid monomers may be used in combination at a ratio of 5% or less. When the firing temperature of the component (B) is 260 ° C. or higher, 10% of acrylate such as ethyl acrylate is used.
% Or more.

The mixing ratio of the components (A) and (B) is (A) / (B) = 10 in consideration of prevention of floating of the metal reflection film.
It is preferably in the range of / 90 to 90/10 (weight ratio), and more preferably in the range of 20/80 to 80/20 (weight ratio). When the mixing ratio of the component (A) and the component (B) is out of the range of 10/90 to 90/10 (weight ratio), the amount of gas generated for the minor component is small, and therefore the temperature from the start of firing to the end of firing is small. It becomes difficult to make the difference 90 ° C. or more, and the effect of preventing the metal reflective film from floating cannot be obtained.

The method of forming a film using the undercoat resin of the present invention is not particularly limited, such as an emulsion method and a water film method. However, even in the emulsion method in which it is necessary to thicken the film to obtain a particularly smooth coating film,
It can be preferably used. The film thickness of the undercoat film is not particularly limited, but since it is usually 1 μm or less, it does not affect the firing rate and firing temperature.

The undercoat resin of the present invention includes
As various additives for preventing blistering of the metal reflective film during firing, known additives such as polyvinyl alcohol borate complex, colloidal silica, and ammonium oxalate may be added.

[0020]

EXAMPLES The present invention will be described below with reference to examples. In addition, the part in an Example shows a weight part. Moreover, the values of the respective physical properties shown in the examples are the values measured by the following methods.

(1) MFT (minimum film forming temperature): A minimum film forming temperature measuring device (manufactured by Takabayashi Rika Co., Ltd.) is used to coat and dry the emulsion on a metal plate having a continuous temperature gradient. The minimum temperature at which a uniform film without cracks was formed was measured. (2) Particle size: Measured by a light scattering method using laser light as a light source (Otsuka Electronics Co., Ltd .; trade name: DLS-600). (3) Measurement of firing temperature: The undercoat resin film was heated to 450 ° C. at a heating rate of 7 ° C./min in an air atmosphere with a thermal analysis device (manufactured by Vacuum Riko Co., Ltd .; trade name TGD9600), and was kept as it was. Hold for 30 minutes to measure the weight loss behavior. As shown in FIG. 1, the results are shown in FIG. 1, where the horizontal axis represents temperature and the vertical axis represents sample weight, and a schematic diagram of a weight decrease curve was prepared. Firing start temperature 1 and firing end temperature 2 were determined at the intersections of the contacts. . (4) Evaluation of aluminum floating: The aluminum vapor deposition film provided on the phosphor surface after the baking treatment was visually measured. ○: No aluminum float △: Partially water bubble-like aluminum float of 5 mmφ or more occurred ×: Aluminum float occurred in less than half of the phosphor surface area × ×: Full aluminum float and aluminum peeling occurred

<Manufacturing Method of Emulsion> [Synthesis Example 1] A 2 liter separable flask was charged with 6 parts of water.
30 parts, 8.0 parts of sodium lauryl sulfate (manufactured by Kao Corporation, trade name Emeral 0) and 2.0 parts of potassium persulfate were added, and a mixture of 388 parts of n-butyl methacrylate and 12 parts of methacrylic acid was added. In addition, heat polymerization was performed at 70 ° C. for 6 hours in a nitrogen atmosphere to obtain an emulsion (A). The evaluation results of the obtained emulsion (A) are shown in Table 1.

[Synthesis Example 2] An emulsion was prepared in the same manner as in Synthesis Example 1 except that a mixture of 224 parts of methyl methacrylate, 144 parts of ethyl acrylate and 32 parts of methacrylic acid was used in place of the mixture of n-butyl methacrylate and methacrylic acid. (B) was obtained. The evaluation results of the obtained emulsion (B) are shown in Table 1.

[0024]

[Table 1] The abbreviations in the table are as follows. nBMA: n-butyl methacrylate MMA: methyl methacrylate EA: ethyl acrylate MAA: methacrylic acid

Example 1 <Formation of Metal Reflective Film> The emulsions obtained in Synthesis Examples 1 and 2 were mixed at a mixing ratio (A) / (B) = 20/80 (weight ratio) to form a film. Formed. The firing start temperature during the firing was 284 ° C, the firing end temperature was 384 ° C, and the temperature difference was 100 ° C. This mixed emulsion was prepared in the proportions shown below to prepare an undercoat liquid for forming a metal film. Acrylic emulsion (solid content) ... 17.0 wt% Poval borate complex ... 0.5 wt% Hydrogen peroxide ... 0.5 wt% Pure water ... 82.0 wt% This undercoat liquid is heated to 42 ° C. in advance at 14 inch CRT. On the phosphor surface, heated with a far-infrared heater, and subjected to filming treatment, and then aluminum is vapor-deposited, heated to 450 ° C. at a heating rate of 7 ° C./min in an air atmosphere, and then held for 30 minutes. Baking treatment was performed to form a metal reflection film. As a result, a uniform aluminum coating was obtained without causing aluminum floating or peeling.

[Examples 2 to 4] <Formation of Metal Reflective Film> The emulsions obtained in Synthesis Examples 1 and 2 were mixed in the proportions shown in Table 2 to form a film in the same manner as in Example 1. Then, using the obtained mixed emulsion, a metal reflective film was formed in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 1] A metal reflective film was formed in the same manner as in Example 1 except that Primal B-74 manufactured by Nippon Acrylic Science Co., Ltd. was used as the emulsion. The evaluation results are shown in Table 2.

[Comparative Examples 2 to 5] The emulsions obtained in Synthesis Examples 1 and 2 were mixed in the proportions shown in Table 2, and a film was formed in the same manner as in Example 1. Then, a metal reflective film was formed in the same manner as in Example 1 using the obtained mixed emulsion. The evaluation results are shown in Table 2.

[0029]

[Table 2]

EFFECTS OF THE INVENTION By using the undercoat resin for forming a metal reflective film of the present invention, a metal reflective film capable of effectively preventing aluminum from floating and peeling off aluminum and having high smoothness and high reflectance is formed. And the productivity of CRTs is improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a weight reduction curve during baking of an undercoat resin for forming a metal reflective film of the present invention.

Claims (3)

[Claims] 1. An undercoat organic resin layer is formed on the inner surface of a cathode ray tube, and a phosphor metal reflective film is formed on the upper surface of the organic resin layer when the undercoat organic resin layer is baked in an air atmosphere. An undercoat resin for forming a metal reflection film on the inner surface of a cathode ray tube, wherein the temperature difference from the start of firing to the end of firing is 90 ° C or more when the temperature rate is set to 7 ° C / minute. 2. The firing start temperature when firing in an air atmosphere is less than 260 ° C., and the firing end temperature is 290 ° C. or higher and 360
A mixture of an organic resin (A) having a firing temperature of 260 ° C. or higher and 300 ° C. or lower and a firing end temperature of 360 ° C. or higher when firing in an air atmosphere. And a mixing ratio thereof is organic resin (A) / organic resin (B) = 10 to 90/90 to 10 (% by weight), for forming a metal reflection film on the inner surface of a cathode ray tube according to claim 1. Undercoat resin. 3. The undercoat resin for forming a metal reflection film on the inner surface of a cathode ray tube according to claim 2, wherein the mixture of the organic resin (A) and the organic resin (B) is an acrylic emulsion.