JPH0678180B2 - Thermochromic film formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a method for forming a thermochromic film which is used for a door glass of an oven toaster.

[Prior art]

Conventionally, there is no example in which a thermochromic film is formed on a glass plate reaching 200 ° C to 300 ° C. For door glass such as oven toaster, 200 ℃ ~ 3
The temperature was relatively high at 00 ° C, and temperature control materials such as paints using thermochromic materials that were commercially available in the past could not be used at all because the heat resistance temperature was low (100 ° C or less).

Therefore, the same applicant developed a thermochromic material having a high heat resistance temperature in view of this point and applied for it on May 15, 1987 (Japanese Patent Application No. 62-119599).

The thermochromic material is composed of a ceramic inorganic compound containing thallium chromate as a main component, and has the characteristic of turning yellow at normal temperature and turning orange when the temperature rises. Use chromic ink. Then, as shown in FIG. 5, a black ink 12 is used as a base on the borosilicate tempered glass surface 11 for silk screen printing, and a yellow dummy color 13 (the color does not change with temperature) and the thermochromic ink.
If 14 is applied and the baking temperature is increased, the tempering effect of the tempered glass 11 is taken during the firing, and there is a drawback that the glass is broken at the temperature (200 ° C to 300 ° C) during operation of the oven toaster, However, when an organic binder is used so that it can be baked at a low temperature, there is not only a problem such as heat-resistant yellowing, but also baking must be performed after applying the thermochromic ink on the glass surface after the strengthening treatment. However, the glass strengthening treatment and the thermochromic ink baking treatment are required in two steps, and there is a drawback that the cost becomes high.

[Means for solving problems]

According to the present invention, as shown in FIGS. 1 to 4, after forming a pattern film on the surface of an unstrengthened glass plate of borosilicate glass with a thermochromic ink of an inorganic compound ceramic mixed with a frit binder, The thermochromic ink is baked at the same time as the glass plate is strengthened.

[Action]

According to the present invention, the pattern film formed by the thermochromic ink is dried and baked at the same time as the borosilicate glass is strengthened, so that the conventional glass strengthening effect is lost when the thermochromic ink is baked. In addition to eliminating the inconvenience of being damaged, the manufacturing process can be omitted because the processing steps are integrated.

〔Example〕

Reference numeral 1 is an electric cooker body such as an oven toaster, 2 is an opening / closing door for opening and closing a front opening of the electric cooker body 1, and is composed of a door frame 3 and a borosilicate tempered glass plate 4, A handle 5 is attached above the center of the glass plate 4.

Reference numeral 6 denotes a dangerous temperature display portion formed in the upper left corner of the glass plate 4, and a black portion 7 is formed on the back surface of the glass plate 4 by stamping an appropriate pattern (design) with a commercially available black paint. The blanked part of part 7 (pattern part)
Is coated with a thermochromic ink 8 containing thallium chromate (Tl ₂ CrO ₄ ) as a main component to form a pattern film 9, and the same color as the room temperature color of the thermochromic ink 8 is formed on at least one side edge of the black portion. The yellow portion 10 (which is the reference color) is formed.

The thermochromic ink 8 (accurately, the thermochromic material in the ink) turns yellow at room temperature and changes to orange in a high temperature range of 200 ° C. or higher. By utilizing the action of changing color from yellow to orange, It is displayed that the glass plate 4 is in a dangerous temperature state.

The method for forming the pattern film 9 will be described in more detail below. First, the composition of the ink 7a forming the black portion 7 is Si
_{O 2, B 2 O 3,} PbO to aid as a main component _{Na 2 O, K 2 O,} CdO, ZnO 2, T
An ink is prepared by mixing a metal oxide of Cu, Cr, Mn as a black pigment into a frit containing i ₂ O, and further adding a binder of polymethylmethacrylate and a terpene as a solvent.

The ink 10a forming the yellow portion 10 is a dummy color for the pattern film 9 and has the same yellow composition that does not change in color and withstands high temperatures, and its composition is mainly B ₂ O _3.
ZnO, Bi ₂ O ₃ frit, mixed with a pigment component that is toned to a specified yellow color, that is, a complex oxide of Pb and Sb, a complex oxide of Ti, Ni, Sb, and as a binder and a solvent. Contains polymethylmethacrylate and terpen.

The composition of the thermochromic ink 8 for forming the pattern film 9 includes a thermochromic powder containing thallium chromate as a main component and a frit binder (SiO ₂ , B ₂ O).
₃ and PbO as the main components and mixed with Na ₂ O, K ₂ O, CdO, ZnO ₂ , TiO ₂ and Li ₂ O as auxiliary agents), polymethylmethacrylate binder and terpene solvent Mix these to make an ink, and add fine powder of aluminum oxide (particle size: 0.1μ
˜1.0 μ).

The compounding ratio at this time is a weight ratio of :: = 1: 1: 0.1 to 0.3.

Then, a black portion 7 is formed on the back surface of the unstrengthened glass of the borosilicate glass plate 4 by using the black ink 7a to print out a pattern, and then the ink 10 is formed.
A yellow portion 10 is formed with a, and a pattern film 9 is formed with the thermochromic ink 8. Then, the glass plate 4 is strengthened.

That is, it is kept in an atmosphere of 700 ° C. for about 3 minutes and then rapidly cooled by air. By the strengthening process of the glass plate 4, the danger display portion 6 formed of the above-described three kinds of ink is fired at the same time as the strengthening process of the glass plate 4. At this time, the aluminum oxide mixed in the thermochromic ink 8 suppresses the boiling phenomenon of the thermochromic ink 8 and also acts as a thickener to increase the viscosity of the ink 8 to form a pattern generated during baking as in the conventional case. The bleeding of the film 9 and the outflow (protrusion) to the outside are prevented.

〔effect〕

Since the present invention is configured as described above, it is possible to increase the baking temperature by using a frit-based binder for the thermochromic ink, and to provide heat resistance, adhesion resistance, and heat yellowing. By not blocking the color change of the thermochromic ink, the color change can be visually recognized, and the borosilicate glass strengthening process and the thermochromic film baking can be performed in one process. A remarkable effect that the process is simple and the manufacturing cost can be reduced can be obtained.

[Brief description of drawings]

FIG. 1 is a front view of an electric cooker on which a pattern film is formed by the method of the present invention, FIG. 2 is a longitudinal sectional view of an essential part of the electric cooker, FIG. 3 is a front view of FIG. 2, and FIG. FIG. 2 is a rear view and FIG. 5 is a front view of a conventional main part. 4: Borosilicate glass, 8: Thermochromic ink, 9:
Pattern film.

Claims (1)

[Claims] 1. A non-strengthened glass plate of borosilicate glass, a pattern film is formed on the surface of an inorganic compound ceramic thermochromic ink mixed with a frit binder, and the glass plate is then tempered at the same time as the tempering treatment. A method for forming a thermochromic film, which comprises firing a chromic ink.