JPH04242003A - Conductive paste - Google Patents

Abstract

PURPOSE:To provide conductive paste contributory to decrease a difference between a temperature in a portion where the conductive paste is printed and a temperature in a portion where the conductive paste is not printed in heating a glass plate, where the conductive paste is partly printed. CONSTITUTION:Bus bars 3 for supplying a current and heating wires 4 for connecting the bus bars 3, 3 are printed on a surface of a window glass plate 1 on a room side by the use of a ceramic collar 2 and silver paste as conductive paste. A coloring material is added into frit constituting the silver paste.

Description

Description: FIELD OF INDUSTRIAL APPLICATION The present invention relates to a conductive paste that can be used as a material for hot wires formed on rear window glasses of automobiles for the purpose of defogging. [0002] The hot wire formed on the rear window glass of an automobile is created by screen printing a conductive paste made by kneading metal powder such as silver, frit (low melting point lead glass), resin, and diluted oil onto the glass surface. It is formed by printing at 600° C. or higher simultaneously with heating during glass bending or rapid cooling strengthening. [0003] Problems to be Solved by the Invention: The conventional conductive paste described above has high heat reflectivity, and when heating glass, the temperature of the part printed with the conductive paste does not rise, and the temperature of the part not printed is the same. The difference becomes larger. As a result, uneven reflection distortion occurs between the printed portion and the unprinted portion, and the strength of the glass itself is also reduced. Particularly in the rear window glass of an automobile, a ceramic color is sometimes applied to hide the joint between the molding and the window glass at the periphery of the window frame from the outside. In this case, ceramic color and conductive paste are printed and fired, but
As described above, since the conductive paste has high heat reflectivity, firing defects occur in the overlapping portions of the ceramic collar. [Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention adds a coloring agent to the frit of a conductive paste made by kneading a metal powder such as silver, a frit, a resin, and a diluent oil. . [Operation] When firing the conductive paste, the surface of the metal powder is covered with the frit, and the surface layer is further covered with the frit. Therefore, when a coloring material is added to the frit, the heat reflectance of the conductive paste becomes lower (the thermal emissivity becomes higher), and the temperature difference between the printed part and the non-printed part during firing becomes smaller. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below with reference to the accompanying drawings. FIG. 1 is a diagram showing an automobile window glass coated with a conductive paste according to the present invention. In the figure, reference numeral 1 indicates an automobile rear window glass before firing, and a ceramic color 2 is provided on the periphery of the surface of the rear window glass 1 that becomes the indoor side to hide the adhesive part of the window glass to the window frame. The busbars 3 for power supply and the hot wires 4 connecting these busbars 3 are printed by screen printing using silver paste, which is a conductive paste. The bus bar 3 and the ceramic collar 2 partially overlap. By the way, the frit constituting the conductive paste is generally made of PbO, SiO2 and B2O3, but in the present invention, Fe2+, N
Colorants such as i2+, Co2+, Cu2+, Cr3+ or V3+ are added. [0010] Next, Table 1 shows the results of comparing specific examples in which the proportion of colorant added was varied and comparative examples in which no colorant was added in terms of reflection distortion and glass strength. However, other conditions in Examples and Comparative Examples are as follows. [0011] The component ratio of the silver paste is 80% by weight of silver.
, the frit is 3% by weight, the resin is 3% by weight, the diluent oil is 14% by weight, the viscosity of the silver paste is 200 poise, the glass on which the silver paste is printed is 200mm in length and width and 3m thick.
m, print area is 40 x 40 mm, firing temperature is 650
℃, baking time is 2 minutes, print thickness after baking is 15μm
And so. Further, the component proportions, visible light transmittance (C light source) and solar radiation transmittance in terms of 1 mm thickness of the frits of each Example and Comparative Example are as follows. (Example 1) PbO 76.6
Weight% SiO2
9.2% by weight B2 O3
9.2% by weight visible light transmittance
72% solar radiation transmittance
48% 0014] (
Example 2) PbO 76.6
Weight% SiO2
9.2% by weight B2 O3
4.2wt% Al2O3
4.0% by weight FeO
6.0% by weight visible light transmittance 36% solar radiation transmittance 32
% (Example 3) PbO 76.6
Weight% SiO2
9.2% by weight B2 O3
4.2wt% Al2O3
4.0% by weight FeO
5.0% by weight NiO
0.5% by weight C
0.5
Weight% visible light transmittance
0.7% solar radiation transmittance
8.0% 0016] (Comparative example; current product) PbO
70wt% SiO2
15% by weight B2 O3
15% by weight visible light transmittance
90% solar radiation transmittance 85% 00
[Table 1] [Effects of the Invention] As is clear from the above explanation and Table 1, according to the present invention, a coloring material is added in the frit to wrap the surface of the metal powder of the conductive paste and cover the surface layer. By adding , the heat reflectance of the conductive paste can be kept low during firing, so the temperature of the part printed with the conductive paste does not rise and the difference in temperature from the part not printed becomes small. As a result, the occurrence of uneven reflection distortion can be suppressed, and a decrease in glass strength can be prevented. Further, even when ceramic colors are printed in layers, the ceramic colors will not fail in firing.

[Brief explanation of the drawing]

[Fig. 1] A diagram showing an automobile window glass coated with a conductive paste according to the present invention.

[Explanation of symbols]

1...Rear window glass, 2...Ceramic color, 3...
Bus bar, 4...heat wire.

Claims (2)

[Claims] 1. A conductive paste made by kneading a metal powder such as silver, a frit, a resin, and a diluent oil, characterized in that a coloring agent is added to the frit. 2. The conductive paste according to claim 1, wherein the addition ratio of the colorant is such that the solar radiation transmittance of the frit is 50% or less when converted to a thickness of 1 mm.