JP4435710B2 - Panel pin paint for cathode ray tube - Google Patents

Description

  The present invention relates to a paint for forming a panel pin that conducts to a panel contact pin of a cathode ray tube.

The tube of the cathode ray tube is formed by combining a funnel portion having a conductive film formed on the inner surface and a panel portion having a fluorescent screen or the like on the inner surface with a frit glass as an adhesive, and then having a temperature of about 400 to 450 ° C. Calcination is performed in the air (this process is called “frit baking”) and integrated. By this frit baking, a conductive film that conducts electricity from the aluminum vapor deposition film on the inner surface of the panel portion to the outside through the panel contact pin is also formed.
The basic composition of the panel pin paint for forming the conductive film is a conductive substance, a binding substance, and a paint substance. The conductive material is a carbon-based material such as graphite or carbon black, or a metal material such as nickel or aluminum, but graphite particles are generally used from the viewpoint of chemical stability and cost. As the binding material, a glass component is used to bond glass as a base material of a cathode ray tube and aluminum as a conduction point. As the coating material, water and an aqueous dispersion material are selected in the case of an aqueous medium, and an organic solvent and a dispersion material compatible with the solvent are selected in the case of a solvent-based medium.
In the frit baking process, the coating material by the panel pin paint burns away the dispersed material in the coating film, and the glass component is softened to be in a molten state. Thereafter, the glass component is cooled and solidified to have adhesive force and conductivity required as a film.
Conventionally, in the case of solvent-based paints, lead borate (PbO—B ₂ O ₃ ) -based glass containing lead oxide has been used as the glass component of the binding substance.
In addition, from the standpoint of the environment in recent years, there has been an active movement not to use materials containing lead substances (lead-free). This tendency is the same in the above-mentioned cathode ray tube manufacturing, and there is a tendency to refrain from adopting lead borate glass containing lead oxide as much as possible.

The present invention provides lead by using an alternative substance that plays an equivalent or higher role in terms of adhesion and conductivity even after firing at 400 to 450 ° C., which was obtained only with PbO—B ₂ O ₃ based powder glass. The object is to obtain an organic solvent-based paint for panel pins that does not contain any of the above.

In order to solve the above-mentioned problems, the present invention first selects a lead-free composition having a softening temperature of 450 ° C. or lower and a glassy low-melting substance (vanadate powder glass or the like) as a glass component.
Secondly, lead-free glass (vanadate powder glass or the like) is 10 to 30 wt%, conductive agent (graphite) is 5 to 30 wt%, binder resin (acrylic resin or the like) is 5 to 20 wt%, and organic It adjusted to the mixture ratio which makes a solvent (toluene, ethyl acetate, etc.) the remainder.
Thirdly, the average particle diameter (d ₅₀ ) of the vanadate glass is adjusted in the range of 1 to ₅ μm in order to balance the specific gravity with the conductive agent (graphite) and to obtain the optimum values of adhesion and conductivity. did. Note that glass particles, with an average particle diameter (d _50), it is also necessary to consider the particle size range. If the maximum particle size is too large, the unevenness of the resulting film will be remarkable, which is not preferable. On the other hand, if the minimum particle size is too small, the surface area of the glass particles increases, so it is necessary to increase the amount of the binder resin for dispersing the particles, and miniaturization increases the cost of pulverization and the like, which is not economical. According to the study of the present inventor, it was found that the particle diameter is preferably in the range of 0.01 to 100 μm.
It was found that an organic solvent-based panel pin paint containing no lead can be obtained by adjusting to the contents described in the above first to third.
In the present invention, a lead-free glass having a softening temperature of 450 ° C. or lower, preferably 400 ° C. or lower, particularly preferably a softening temperature of 370 ° C. or lower is used as the glass material for the reasons described later. The lead-free glass is preferably a vanadium-containing glass, and the vanadate powder glass is particularly preferable as an example of these. In addition, other than vanadium-containing glass, lead-free glass such as borate glass or phosphate glass can be used as the glass particles of the present invention as long as it satisfies the glass temperature characteristics (softening temperature is 450 ° C. or lower). In addition to the above acrylic resin, a phenol resin, an epoxy resin, or the like can be used as the binder resin. Furthermore, as organic solvents, general paint solvents such as toluene and ethyl acetate, alcohol-based and ester-based solvents can be used.

The panel pin paint for conducting to the panel pin of the cathode ray tube of the present invention does not use any PbO-B ₂ O ₃ glass, and therefore does not contain any lead component and does not cause environmental pollution. Even after baking (frit bake) at 450 ° C., it exhibits adhesion and conductivity that are equal to or higher than when lead-containing glass is used.

  The following examples illustrate the best mode for carrying out the present invention.

1. Selection of Powdered Glass Table 1 shows examples of examination of powdered glass with a blending ratio of 25% by weight of powdered glass, 10% by weight of graphite and 5% by weight of acrylic resin. In order to obtain a necessary adhesive force by baking at 400 to 450 ° C., powder glasses having a glass softening temperature or lower of PbO—B ₂ O ₃ powder glass, that is, three types of vanadate powder glasses having a softening temperature of 450 ° C. or lower are used. The PbO—B ₂ O ₃ system powder glass and the phosphate powder glass (1) and (2) having a high glass transition point were used. As a result, the glass softening temperature of vanadate powder glass is low, and in some cases, tape peeling shows 0/100 and good results in a tape peeling (cross cut) test after baking at 450 ° C. for 10 minutes. However, the specific resistance was 1.1 Ω · cm, showing a resistance value approximately twice that of the PbO—B ₂ O ₃ powder glass, and adjustment by the blending amount was examined.

2. Examination of blending amount Table 2 shows an example of blending amount. In order to improve the adhesiveness at room temperature, it is necessary to blend 5 wt% or more of acrylic resin, and in order to obtain sufficient adhesiveness after baking at 450 ° C. for 10 minutes, 10 wt% of vanadate powder glass is required. Met. Nevertheless, the conductivity (specific resistance) after 10 minutes at 450 ° C. was low and good compared to 1.1 Ω · cm.
From the results of Table 2, it was found that the blending amount of the binder resin is preferably 5 to 20 wt%, the vanadate powder glass is 10 to 30 wt%, and the graphite is preferably 5 to 30 wt%. The average particle size (d ₅₀ ) of the vanadate powder glass used in Examples 1 and 2 is 0.7 μm.

3. Examination of average particle diameter of vanadate powder glass Table 3 shows an examination example based on the average particle diameter (d ₅₀ ) of vanadate powder glass. The coarser the average particle diameter, the faster the sedimentation rate of powder glass (specific gravity 4.3) with higher specific gravity, and graphite (specific gravity 2.2) remains on the surface layer by firing at 450 ° C. for 10 minutes. Although improved, the surface layer (graphite portion) peels off when the tape is peeled off. Further, if the particle size is made fine, the surface layer is covered with glass, so that the conductivity is deteriorated. From this result, it was found that the average particle diameter (d ₅₀ ) is preferably 5 μm or less (Formulation Examples 10 to 14).

Table 4 shows a comparison of evaluation results of paints using lead oxide and lead-free glass of the present invention.
The present invention can be replaced since it is configured as shown in Table 4, lead-free and PbO-B ₂ O ₃ -based glass powder those using the same quality panel pins paints with vanadate powdered glass.

The panel pin paint of the present invention does not contain any lead component, and has the same performance as a paint using a conventional PbO-B ₂ O ₃ based powder glass in both adhesive strength and conductivity. It is used as a paint for panel pins that conducts to the panel pins of the considered cathode ray tube.

Claims (2)

In the panel pin paint that conducts to the panel pin of the cathode ray tube, the compounding amount of the graphite particles is 5 to 30% by mass, the compounding amount of the vanadium-containing glass particles is 10 to 30% by mass, and the compounding amount of the binder resin is 5 to 20% by mass. and the amount of the organic solvent and the balance, panel pin paints a cathode ray tube said glass particles, wherein the glass softening temperature of 450 ° C. or less. 2. The panel pin paint for a cathode ray tube according to claim 1, wherein the vanadium-containing glass particles have an average particle diameter in the range of 1 to 5 [mu] m.