JPH0286660A - Heat-sensitive resin composition and heat-sensitive material - Google Patents

Abstract

PURPOSE:To obtain the title composition which can discolor or fade without fail in a specified atmosphere at an elevated temperature by uniformly dispersing a pigment which can discolor or fade by heating and porous inorganic particles in a resin which can discolor by heating. CONSTITUTION:5-30wt.% resin which can discolor by heating (e.g., phenolic resin) is dissolved in an organic solvent to obtain a resin solution (A). Separately, a dispersion formed by dispersing at most 5wt.% pigment which can discolor or fade by heating [e.g., Oil Orange S (trademark)] in an organic solvent is mixed with porous inorganic particles of a mean particle diameter <=0.1mm and a pore volume of 0.5-3.0cm<3>/g, and the organic solvent is removed from the resulting mixture, and the residue is dried to obtain pigment-containing inorganic porous particles (B). Component B is added to component A, and the resulting mixture is uniformly mixed to obtain a heat-resistant resin composition. This composition is applied to a sheetlike support and dried to obtain a heat-sensitive material.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a heat-sensitive resin composition and a heat-sensitive material, and in particular,
The present invention relates to a heat-sensitive resin composition that changes color or fades under predetermined heating temperature conditions and that can be detected in the heating temperature atmosphere by the color change, and to a heat-sensitive material using the heat-sensitive resin composition.

[Prior art and its problems]

In general, for products that are manufactured through a process of heat treatment under predetermined heating conditions, such as resin molded products and rubber molded products, it is necessary to check whether the heat treatment was performed under appropriate temperature conditions. It is necessary to do L'2.

Conventionally, two convenient means used to check whether or not the treatment has been carried out under the above-mentioned appropriate temperature conditions include liquid temperature-sensing paints that change color when the temperature reaches a predetermined temperature, and liquid temperature-sensing paints that have thermal properties. Temperature-sensing sheets and the like with paint coated on the sheet are known, and by exposing these to a heated atmosphere during heat treatment in the same way as molded products and observing the color change of the temperature-sensing paint or temperature-sensing sheet. This determines whether the molded product has been heat treated under appropriate temperature conditions.

However, the temperature-sensing paint and temperature-sensing sheet whose color changes to i at the predetermined heating temperature described above change color extremely sensitively to temperature changes, and are excellent as temperature-sensing materials. It has the problem that it is difficult to obtain and is extremely expensive, so it cannot be used generally.

The present invention solves the above-mentioned problems of the conventional temperature sensing materials, and can be easily prepared from inexpensive and easily manmade materials, and can be heated in a predetermined heating temperature atmosphere compared to conventional temperature sensing materials. The object of the present invention is to provide a thermosensitive resin composition that reliably discolors or fades over time, and a thermosensitive material using the thermoplastic composition.

[Means for solving problems]

In order to achieve the above object, the thermosensitive resin composition of the present invention has a composition in which a pigment that changes color or fades when heated and inorganic porous particles are uniformly dispersed in a resin that changes color when heated, Further, the heat-sensitive material of the present invention includes a resin that changes color when heated, and a pigment that changes color or fades when heated.
It has a structure in which a heat-sensitive resin composition in which inorganic porous particles are uniformly dispersed is coated on a sheet-like substrate.

[Specific Structure of the Invention] The resin that changes color when heated, which is used in the thermosensitive resin composition of the present invention, changes color at room temperature when exposed to heating temperature conditions within a temperature range that does not cause the resin to decompose or cause scorching. Any resin can be used as long as the color of the resin under normal conditions changes under predetermined heating temperature conditions and the color change of the resin can be visually confirmed. For example, phenolic resin [for example, Unipex S , N type (manufactured by Unitika)],
Examples include polyimide resins (for example, Kelimide 601 (manufactured by Nippon Polyimide Co., Ltd.)).

The pigment that changes color or fades when heated is used in the thermosensitive resin composition of the present invention, and when exposed to heating temperature conditions within a temperature range that does not cause the resin that changes color when heated to decompose or cause scorching. Any pigment can be used as long as the color of the pigment under normal conditions at room temperature changes by discoloration or fading under predetermined heating temperature conditions, and the color change of the pigment can be visually confirmed, for example, Orange pigment Oil Orange PS (trade name, manufactured by Orient Chemical Co., Ltd.), green pigment Oil Blue 2-N (trade name, manufactured by Orient Chemical Co., Ltd.), red pigment ROB-B (trade name, manufactured by Orient Chemical Co., Ltd.), Examples include Spirit Black (trade name, manufactured by Orient Chemical Co., Ltd.), which is a black pigment.

The inorganic porous particles used in the thermosensitive resin composition of the present invention preferably have an average particle size of 0.1 mm or less, and have a pore volume of 0.5 to 3.0 cffl/g.
For example, silica-based porous particles [for example, Thyloid 244 (average particle size 1.8 μm, pore volume 1.6 ml/g) (manufactured by Fuji Davison Chemical Co., Ltd.)] are representative examples. It will be done.

The preferable mixing ratio of the pigment and resin to the inorganic porous particles varies depending on the pore volume of the inorganic porous particles, but the total volume of the pigment and resin components to the pore volume of the inorganic porous particles is 1 to 10. It is preferable to add the amount in a range of about twice as much.

In order to uniformly disperse the pigment that changes color or fades when heated and the inorganic porous particles in the resin that changes color when heated, first, the resin is dissolved in an organic solvent and
Prepare a weight percent resin solution.

On the other hand, the pigment is dispersed in an organic solvent to prepare a pigment dispersion having a pigment concentration of 5% by weight or less, and the inorganic porous particles are added to this pigment dispersion, stirred and mixed, and then an organic solvent is removed and dried to obtain pigmented inorganic porous particles.

Next, the inorganic porous particles to which the pigment has been added are added to the resin solution prepared above, stirred and mixed, and uniformly dispersed to obtain the thermosensitive resin composition of the present invention.

In the heat-sensitive resin composition according to the present invention prepared above, since the inorganic porous particles are uniformly dispersed in the resin and pigment components, oxygen in the air does not penetrate into the resin and pigment components. Therefore, under heating temperature conditions, the entire thermosensitive resin composition uniformly, quickly, and reliably changes color or fades. Furthermore, by changing the color in two stages: the temperature at which the resin changes color and the temperature at which the pigment changes color or fades, it becomes possible to detect more precise heating temperature conditions.

The heat-sensitive resin composition according to the present invention configured as described above can be used as a temperature-sensing material because the heat-sensitive resin composition alone changes color or fades when exposed to an atmosphere at a predetermined heating temperature. By coating the thermosensitive resin composition of the present invention on a sheet-like base material to obtain a thermosensitive material, a temperature-sensing material that can be used more easily can be obtained.

As the sheet-like base material used in the heat-sensitive material according to the present invention, heat-resistant sheet-like members such as glass cloth, glass fiber nonwoven fabric, ceramic sheets, metal plates, etc. can be used without limitation. Sheet-like base materials preferably used for the heat-sensitive material include glass cloth,
It is a metal plate.

In order to prepare a heat-sensitive material according to the present invention by coating the heat-sensitive resin composition according to the present invention on the above-mentioned sheet-like base material, pigments and inorganic porous particles are added to the resin solution obtained at the time of preparing the heat-sensitive resin composition. It can be easily prepared by impregnating the sheet-like base material in a dispersion in which the dispersion is uniformly dispersed, or by applying the dispersion on the sheet-like base material by a conventional method and then drying the dispersion. .

In the heat-sensitive material according to the present invention obtained above, the resin component and pigment component are coated on the sheet-like base material in a state in which the inorganic porous particles are uniformly dispersed.
Oxygen in the air easily penetrates into resin components and pigment components,
Under heating temperature conditions, the resin components and pigment components in the resin composition are heated uniformly, quickly, and reliably, almost unaffected by the thickness of the thermosensitive resin composition applied onto the sheet-like substrate. It may change color due to discoloration or fading. Furthermore, by changing the color in two stages: the temperature at which the resin changes color and the temperature at which the pigment changes color or fades, it becomes possible to detect more precise heating temperature conditions.

〔Effect of the invention〕

As described above, the present invention constitutes a thermosensitive resin composition by uniformly dispersing inorganic porous particles in a resin material that changes color when heated and a pigment that changes color or fades, which are inexpensive and easily available. Things are easy to prepare;
In addition, it can be supplied at low cost, and when exposed to predetermined heating temperature conditions, the inorganic porous particles in which the resin and pigment components are uniformly dispersed make it easier for oxygen in the air to permeate the resin and pigment. The heat-sensitive resin composition changes color uniformly, quickly, and reliably in two stages: the discoloration or fading temperature of the pigment and the discoloration temperature of the resin. In the case of a heat-sensitive material coated with a heat-sensitive material, the heat-sensitive resin composition can be heated at two stages: the discoloration or fading temperature of the pigment and the discoloration temperature of the resin, almost unaffected by the thickness of the heat-sensitive resin composition coated. The color changed uniformly, quickly, and reliably, and the molded product was heat-treated in an appropriate temperature atmosphere by placing some of the cut pieces in a heating furnace with the molded product material. This has excellent effects such as being able to easily and reliably check whether the heat-sensitive material has changed color by observing the color change.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the embodiments of the present invention are not limited thereto.

Example 1 Oil Orange PS, an orange pigment that fades when heated
(trade name, manufactured by Orient Chemical Co., Ltd.) in toluene to prepare 100 ml of a 1% by weight pigment dispersion, and add silica-based porous beads [Syroid 244 (Fuji Davison Chemical) as inorganic porous particles to this pigment dispersion. After stirring and mixing, toluene was removed and drying was performed to obtain pigmented inorganic porous particles.

On the other hand, 300 ml of a 10% by weight ethanol resin solution was prepared by dissolving a phenolic resin (Unihex S (manufactured by Unitika)) as a resin that changes color upon heating in ethanol. The particles were added and mixed by stirring to prepare a dispersion.

Next, a tape-shaped glass cloth [Glass Cloth Tape WF3005N (manufactured by Nittobo Co., Ltd.)] was added to the dispersion prepared above.
], dried, and coated with the thermosensitive resin composition of the present invention on a glass cloth to prepare thermosensitive material sample No. 1.

Comparative Example 1 Comparative heat-sensitive material sample No.
, 2 was prepared.

The heat-sensitive material samples No. 1 and 2 obtained above were placed in an electric furnace, and the temperature was gradually raised from room temperature to 240° C. over 10 hours, and the color change of the samples was visually observed.

In sample No. 1 according to the present invention taken out after 5 hours (under heating conditions of 140°C), the orange color of the sample at normal room temperature faded and changed to pale yellow. In sample No. 2, the orange color still remained. In addition, sample No. 1 according to the present invention taken out after the 10th hour (under heating conditions of 240'C) had further discolored to reddish brown, while comparative sample No. 2 had no discoloration to reddish brown. It wasn't enough.

In other words, according to the heat-sensitive material described above, the color change occurs quickly, uniformly over the entire surface, and reliably, and in one sample, the color change temperature of the resin and the color change or fading temperature of the pigment (as described above) In this example, it is possible to detect whether each heating temperature stage (140°C and 240°C) has passed, and when heat-treating the molded product material, the heat-sensitive material according to the present invention is placed in the heating furnace together with the molded product material. By placing the heat-sensitive material in the same manner, it is possible to check whether the inside of the heating furnace has reached a predetermined temperature and whether or not the intended heat treatment has been performed by checking the color change of the heat-sensitive material.

Claims (4)

[Claims] (1) A thermosensitive resin composition characterized in that a pigment that changes color or fades when heated and inorganic porous particles are uniformly dispersed in a resin that changes color when heated. (2) A heat-sensitive material characterized by coating a sheet-like base material with a heat-sensitive resin composition in which a pigment that changes color or fades when heated and inorganic porous particles are uniformly dispersed in a resin that changes color when heated. . (3) The thermosensitive resin composition according to claim 1, wherein the resin that changes color upon heating is a phenol resin or a polyimide resin. (4) The thermosensitive resin composition according to claim 1, wherein the inorganic porous particles are silica-based porous particles having an average particle size of 1 mm or less.