JPS6251987B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to the production of an organic film used as a base for forming a metal reflective film after forming a phosphor layer on the inner surface of the panel in the manufacturing process of cathode ray tubes, such as color picture tubes. The present invention relates to the composition of a filming emulsion used for forming the film. [Background of the Invention] Generally, when forming the phosphor surface of a color picture tube, a phosphor layer consisting of three color phosphors of green, blue, and red is formed on the inner surface of the panel, and then aluminum is vapor-deposited. In order to make this reflective film smooth and highly reflective, a filming process is performed prior to aluminum vapor deposition. This filming step is a step in which unevenness on the surface of the phosphor layer is smoothed by covering it with an acrylic resin film, and methods include the lacquer method and the emulsion method. The present invention relates to this emulsion method. Generally, the acrylic emulsion conventionally used in the emulsion method is manufactured by Rohm & Hass in the United States.
Rophlex B-74 or Primal B-74 manufactured by Nippon Acrylic Co., Ltd., both of which contain emulsion polymerization of methyl methacrylate, methyl acrylate, and acrylic acid. By the way, one of the most important things in the filming process is to make the formed film smooth in order to increase the reflectance of the aluminum vapor-deposited film and improve the brightness of the fluorescent surface. It is necessary to make the film thicker. However, the thicker and smoother the film is, the more likely it is that the aluminum film will blister or peel off as shown in FIG. 1 due to decomposed gases from acrylic resin or the like during the baking process after aluminum deposition. In Fig. 1, 1 is the face panel;
2a, 2b, and 2c are picture elements made of green, blue, and red phosphors, respectively; 3a is an aluminum film; and 3b is an aluminum bulge. For this reason, conventionally, as shown in Figures 2a (front view) and b (enlarged sectional view), cracks are created in the film around the phosphor picture element, and the cracks in the aluminum film that occur in this area are removed. Measures are taken to prevent blistering and peeling by allowing decomposition gas to escape. The following compositions of typical filming liquids for this method are known. [Acrylic emulsion (RhoplexB-74) 13-18wt% (solid content) PVA borate ester (Unisize) 0.2-1wt% Colloidal silica 0.2-1wt% Hydrogen peroxide 0.1-1wt% Ammonia Appropriate amount for adjusting PH value Water Remainder] However, this method has the following drawbacks. That is, as mentioned above, the filming liquid must be a mixture of many different materials;
The film formed is hard and tends to cause cracks in the phosphor picture element, reducing the brightness of the phosphor surface. [Object of the Invention] The present invention was made in view of the above circumstances, and its purpose is to provide a material that has a simple composition, is soft, does not damage the phosphor pixels, and effectively prevents aluminum from blistering. It is an object of the present invention to provide a filming emulsion for a cathode ray tube, which can form a film capable of forming a film. [Summary of the invention] In order to achieve such an object, the present invention has the following features:
In addition to methyl methacrylate and ethyl acrylate, n-butyl methacrylate, which has a low thermal decomposition temperature and forms a soft and stretchable film, is used as the copolymerizing composition of the acrylic resin to be emulsion polymerized. Hereinafter, the present invention will be explained in detail using Examples. [Embodiments of the Invention] An acrylic emulsion having the following copolymer composition is used.

〔Effect of the invention〕

As explained above, according to the present invention, by using a copolymer of methyl methacrylate, ethyl acrylate, and n-butyl methacrylate as an acrylic emulsion, the amount of film produced per unit time during baking can be reduced. Since the amount of pyrolysis gas can be reduced, aluminum blisters can be effectively prevented without using a variety of materials as in the past. In addition, the formed film is soft and does not damage the phosphor picture elements.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing how aluminum blisters occur when filming is performed using a conventional filming emulsion, and Figs. 2 a and b are cross-sectional views showing conventional measures to prevent aluminum blisters. 3 are graphs showing the effects of the present invention in comparison with the conventional one.

Claims (1)

[Claims] 1. A filming emulsion for cathode ray tubes whose main component is an acrylic emulsion obtained by copolymerizing methyl methacrylate, ethyl acrylate, and n-butyl methacrylate.