JPH0678179B2 - 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 had low heat resistance (100 ° C or less) and could not be used at all.

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 property of turning yellow at room temperature and turning orange when the temperature rises. Use thermochromic ink. Then, as shown in FIG. 5, a black ink 12 is used as a base for silk screen printing on the surface 11 of the borosilicate tempered glass, and a yellow dummy color 13 is formed thereon.
(The color does not change with temperature) and the thermochromic ink 14 is applied and baked.

[Problems to be solved by the invention]

However, since the baking temperature of the thermochromic ink 14 is extremely high at 650 ° C to 700 ° C, the frit which is the binder of the thermochromic ink 14 and the thallium chromate of the thermochromic material are melted and flowed out by the high temperature heating during the baking. However, there is a drawback that the pattern value is bleeding or the ink is squeezed out of the black ink portion 12 which is the base, thereby deteriorating the commercial value.

Therefore, try variously changing the frit component of the binder in the thermochromic ink 14, or change the compounding ratio of the binder and the thermochromic pigment, or change the firing temperature, change the binder of the black ink 12 of the base. But I couldn't improve it at all.

[Means for solving problems]

As shown in FIGS. 1 to 4, the present invention forms a pattern film on the surface of a glass plate with an inorganic compound-based thermochromic ink in which a frit-based binder and aluminum oxide powder are mixed, and then, in a high temperature atmosphere. I try to bake.

[Action]

According to the present invention, the thermochromic ink causes a boiling phenomenon because it becomes a high temperature at the time of baking the pattern film formed of the thermochromic ink, but at this time, the aluminum oxide powder mixed in the thermochromic ink causes the boiling phenomenon. And the action of a thickening agent that increases the viscosity of the ink are prevented, and the conventional pattern film bleeding and outflow to the outside can be prevented.

〔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.

When the amount of aluminum oxide added to the thermochromic ink 8 is 0.1% or less by weight, bleeding occurs, and when 0.3% or more is added, the color change of the thermochromic material is affected, which is not preferable. or,
When aluminum oxide was added, the color tone at room temperature became vivid, and the color change was visually recognized better than when the aluminum oxide was not added.

〔effect〕

Since the present invention is configured as described above, the aluminum oxide added to the thermochromic ink can prevent the bleeding of the pattern film during firing and the outflow to the outside, and the finish of the pattern film becomes good, and It is possible to exert various remarkable effects such that the color change performance of the chromic material is also improved.

[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 (2)

[Claims] 1. A thermochromic coating formed by forming a pattern coating on a glass plate surface with an inorganic compound-based ceramic thermochromic ink in which a frit-based binder and aluminum oxide powder are mixed, and then firing in a high temperature atmosphere. Forming method. 2. The method for forming a thermochromic film according to claim 1, wherein the aluminum oxide powder is blended with a thermochromic pigment powder in a weight ratio of 0.1 to 0.3.