JPH02278688A - Heat insulating board or heating board - Google Patents

Abstract

PURPOSE:To enable safe and effective heat insulating and heating by coating a heat generator with an insulating layer, and providing an adiabatic layer for covering the exothermic body and the insulating layer as a whole. CONSTITUTION:An insulating layer 2 is disposed under a substrate 1 made of aluminum. The insulating layer 2 is prepared by a heat resistant resin, for example, a resin composition incorporating Al2O3 into a polyimide resin. An exothermic body 3 is disposed under the insulating layer 2 provided with an electrode terminal 4. The exothermic body 3 is coated with a heat generating film incorporating polyimide resin into globular graphite, followed by heat treatment. The electrode terminal 4 is a Ni-galvanized copper wire network, and is disposed at both ends of the heat generating film. Therefore, heat insulating and heating can be obtained with high safety and practicability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat-retaining or heating plate, and particularly to a heat-retaining or heating plate comprising a heating element whose temperature can be automatically controlled.

[Conventional technology]

Heaters include gas stoves, electric heaters, etc. These conventional heaters use gas combustion, red-hot nichrome wire heaters,
Most of them consist of red-hot heaters such as red-hot sheathed heaters and red-hot silicone heaters.

[Problem to be solved by the invention]

Conventionally, in ordinary households, the thermal power or temperature of gas stoves, incandescent heaters, etc. is controlled manually in most cases. Therefore, for example, if something spills out of the pot while cooking tempura, or if you forget to turn the pot on, or if you are careless, the oil will overheat and the temperature of the oil will rise to 200 degrees, causing a fire. There is. There are some that come with a temperature sensor to adjust the temperature, but they are extremely expensive and have limited functionality. In order to avoid such dangers and to obtain dishes with excellent results, there is a desire for a heating plate that can always be adjusted to a specific temperature without causing overheating, and also a heating plate that does not cause overheating. This is what is desired.

[Means to solve the problem]

The present inventor previously proposed a conductive heat-generating paint (Japanese Patent Application No. 62263954) containing carbon powder mainly consisting of particles consisting of spherical bodies with a particle size of 500 μm or less and a synthetic resin as main components.
and proposed a conductive heating element (Japanese Patent Application No. 62-263955) whose temperature can be automatically controlled, which is made by applying the paint to a solid surface of a desired shape provided with electrode terminals to form a conductive coating film. However, as a result of further research on the application of this conductive heating element, it was discovered that heating plates made of conductive heating elements that can automatically control the temperature solved the problems that conventional heaters such as stoves had. The present invention was achieved based on the discovery that this is the case.

That is, the present invention provides an insulating layer on the outer bottom of the substrate, a heating element whose temperature can be automatically controlled on the insulating layer, a heat insulating layer covering the heating element and the entire insulation layer. The present invention relates to a temperature-controllable heat-retaining or heating plate characterized by being provided with a layer.

Examples of the substrate include metals such as iron, copper, aluminum, stainless steel, and alloys. Aluminum is preferred because it conducts heat well and does not rust.

Metals have good thermal conductivity, great strength, and are beautiful. Ceramics and foamed ceramics can also be used.

The electrically insulating layer is made of a heat-resistant resin such as polyimide resin, polyamide resin, epoxy resin, polyfluorocarbon resin, etc., and a heat-resistant filler such as AQ203Zr02.
A resin composition in which powders of SiC2, MgO, Cr2O3, SiC2, titanocarbosilane, etc. are mixed is used. The mixing ratio of the heat-resistant filler and the heat-resistant resin can be selected arbitrarily, but is 1:0.2 or more, preferably 1:0.7-
It is 1.8. A heat-resistant filler conducts heat more easily than a resin, but if the resin is less than 0.2, the strength will decrease and it will be difficult to apply. The thickness of the insulating layer is 0.1-1 ni
It is assumed to be about n.

Further, as an electrical insulating layer, Ni and Cr are used on the metal plate.

Go is thermally sprayed to form an intermediate layer, and then A1□03 (white alumina) is applied as an oxidation layer on top of the intermediate layer.

ZrO, MgO, Cab, 5in2, 5i203°Y2
O3 alone or a mixture, or a compound containing these ceramics as the main component, coated by plasma spraying, chemical vapor deposition (CVD), explosive spraying, or as a nitriding system, A]N, Si3N4゜BN, etc. The purpose can also be achieved by thermal spraying SjC, ZrxCry, etc. as a carbonized material.

The thickness of Nj, Cr as an intermediate layer is about 20-50μ
m, and the main thermal spray material is ha170. +Y.

03, Zr○+MgO+Ca○, 5jO2 (or 5i203)+MgO+Y2O3+B, and the thickness of these is 100 to 300 μm. These spray materials are selected to match the coefficient of thermal expansion of the substrate metal.

As a result, a heating element with good insulation properties and good thermal conductivity can be obtained, and is durable at high temperatures. The heat resistance temperature of ceramics and polyimide + A1□o3, which are heat-resistant insulators, is 500°C and 250°C1, and the thermal conductivity is 1.0~
1.2 and 0.2(cal,/cm-de(<5ee
), and the temperature variations are ±2°C and ±5°C.

The conductive heating element, which is provided at the bottom of a substrate having an insulating layer and whose temperature can be automatically controlled, has electrode terminals provided at desired intervals on the bottom insulating layer of the substrate, and particles made of spherical bodies with a particle diameter of 0.5 μm or more and 500 μm or less. It is obtained by providing a conductive coating film containing mainly carbon powder and synthetic resin. The electrode terminals are made of copper, aluminum, copper plated with nickel or tin, wires, plates, nets, etc., and are installed on both sides. This heating element can also be made by coating or impregnating the surface of a substrate with electrode terminals in a desired shape with a conductive paint similar to that described in "-", and can also be provided on the above-mentioned insulating layer. . This substrate may be made of plastic, ceramics, wood, fiber, paper, electrically insulating heated metal material, or other materials.

Spherical carbon particles are produced by polycondensation of low-molecular compounds by heat-treating bituminous materials such as coal tar, coal tar pitch, and heavy petroleum oil at a temperature of 350°C to 500°C for a long time using a method such as Tiller. Meso carbon microbeads (meso carbon m1cr) are produced by repeating the reaction, polymerizing them, and separating optically anisotropic spheres from the produced carbon.
Alternatively, it is produced by graphitizing nearly spherical coke, which is carbonized synthetic resin, through heat treatment reduction at several hundred degrees to several hundred degrees in three steps.

In addition, the synthetic resins used include, for example, polyimide resin, polyamide 1 (resin, polyphenylene oxide resin, silicone resin, polytitanocarbosilane resin, phenol resin, epoxy resin, polyparahenic acid resin, polyurethane resin, polyester resin, polynylene resin, etc.). These include ether ketone resin, polyphenylene sulfide resin, polyflon resin, polyolefin resin, vinyl chloride resin, etc., and a resin having a softening temperature or decomposition temperature can be selected depending on the desired target temperature of the coating film.

The ratio of the carbon particles to the synthetic resin binder of the present invention depends on the desired heating temperature, the size of the heating surface, etc.
Various selections are made depending on the type and combination of synthetic resin, etc., but - for boat fishing, 100 parts by weight of carbon powder (hereinafter referred to as parts)
10 to 190 parts, preferably 20 to 60 parts.

If the proportion of synthetic resin is less than 10 parts, a product with a small resistance value and a high-temperature heating element (applicable to those with a wide heating surface) can be obtained, but the coating film strength is insufficient and the temperature coefficient of electrical resistance is low. becomes small and temperature unevenness tends to occur. On the other hand, if the amount of the synthetic resin is 190 parts or more, the current necessary for heat generation cannot be obtained (the resistance value becomes excessive), making it unsuitable for practical temperatures. That is, the electrical resistance value is 0.5 Ω/mouth at room temperature (Ω/mouth represents the electrical resistance value for a square area)
If it is less than 300Ω/mouth, the current will be too low, resulting in an excessively uneven high temperature, and if it exceeds 300Ω/mouth, the current will be insufficient, the power will drop, and it will be difficult to obtain the desired temperature.

Hardeners can also be added to facilitate dry assimilation or hardening of the paint or paste in a short time.

These curing agents can be selected depending on the resin, and include aliphatic or aromatic polyamines, polyisocyanates,
Common hardening agents such as polyamides, amines, thioureas, acid anhydrides, etc. are used.

In addition, stabilizers, plasticizers, antioxidants, etc. may be used as appropriate.

In the case of a large heat generating surface, 1 at normal temperature with low electrical resistance.
If the area is small, a resistor with a high electrical resistance of 250Ω/hole at room temperature is used, and generally a material with an intermediate value is used. In addition, in the present invention, the surface temperature of the heating element can be adjusted to any temperature up to about 450°C by combining the graphite size, heat treatment temperature, paint composition, coating thickness, applied voltage, etc.
It can be obtained stably for a long time (at an environmental temperature of -30°C to +40°C).

In the case of the insulating or heating plate of the present invention, the temperature of the heating element is approximately 40°C.
It can be stably held at a desired specific temperature between 'C to 450'C for a long time. For example, to keep the floor or sauna warm at about 40°C, for panel heaters or sauna inner wall panels, attach a cloth that emits far infrared rays to 60-100°C, and for cake heating plates, heat at 200°C or a fish grill heating plate. It is adjusted to various temperatures, such as 450°C.

This coating material mainly composed of carbon particles and synthetic resin can be applied to various coating methods such as brush coating, roller coating, spray coating, electrostatic coating, electrodeposition coating, powder coating, etc. Other additives or auxiliaries can be added depending on the dipping application.

These additives and auxiliaries can be, for example, diluting solvents, anti-settling agents or dispersants, antioxidants, other pigments and other necessary additives.

The thickness of the conductive exothermic coating film is not limited to 0.3 mn+.
~7 own is appropriate.

The temperature of the heating element of the present invention is automatically controllable, and the electrical resistance increases at a specific temperature, and the temperature coefficient of electrical resistance rapidly increases (FIG. 2).

This heating element usually has an insulating partition on the heat-generating coating, and by changing the resistance value, the electric power (watts) can be adjusted, and the temperature of the heating plate can be further adjusted. That is, as shown in FIG. 4, the exothermic coating film is partitioned by an insulating partition 8, electrode terminals A, B, C, X, and Y are provided, and resistance is established between XA, X-B, and X-C. The power (watts) can be adjusted by using the change in the magnitude of the value. Also, by changing the thickness of the coating between X-Y, A-1, AB, and BC, and changing the content of conductive particles, the power can be arbitrarily set to strong, medium, or weak. I can do it. This further prevents overheating of the heating plate and at the same time saves power.

The outside of the heating element is covered with an insulating layer. This insulating layer may be the same as the above-mentioned insulating layer, and may be made of a mixture of heat-resistant resin and heat-resistant filler, and may have the same thickness.

The heating element covered with the insulation layer is then completely covered with a further insulation layer. The material of this heat insulating layer is A]2031S
It is made of fibers such as JO2, wool, glass fibers, foamed ceramic plates, foamed glass plates, etc., and its thickness can be 10 to 100 m depending on the allowable temperature.

The size of one side of the heat insulation plate or heating plate is 10~] OOOa
It is n.

The heating plate and heat-retaining plate of the present invention can be used, for example, as a heating plate for cake baking, a heating plate for grilling fish, a heating plate for grilled meat, a panel heater or a sauna inner wall board, an indoor heater, a floor of a fixed-temperature warehouse, a heating plate, or a wall heat-insulating board. It is effective as a heat insulating board such as a roof heat insulating board.

[Effect]

The heat retention or heating plate of the present invention does not require any other means or operation, and uses a heating element that can constantly maintain a specific temperature and whose temperature can be controlled, so it can safely and effectively retain heat. It becomes possible.

〔Example〕

Examples of the present invention will be described below with reference to the drawings, but the present invention is not limited to these examples.

Example 1 FIG. 1 shows a heat insulating or heating plate of the present invention. In FIG. 1, a substrate 1 is made of aluminum (or copper, iron, stainless steel, etc.), and an insulating layer 2 is provided on the bottom of the substrate. The insulating layer 2 is made of heat-resistant resin, such as polyimide resin, and Al2O3 in a weight ratio of l:o, 2 or more.
It is preferably obtained from a resin composition blended in a ratio of 1:1, and its film thickness is 0.1 to 1 m. A heating element 3 (20×20(1)) is installed below the insulating layer. The heating element 3 has an electrode terminal 4 provided on the insulating layer, and has a thickness of 10 to 20 μm.
0.33 parts of polyimide resin per 1 part by weight of spherical graphite of φ
A heat-generating coating film consisting of a mixture in the proportion of 3 parts by weight
It was coated to a thickness of +m and was heat treated at around 200°C. Electrode terminals are Nj plated 0, 2 to III.
This is a copper wire net of IIIφ, which is provided at both ends of the heat-generating coating. This heating element showed a temperature-resistance curve shown in FIG. 2, and exhibited a characteristic in which the electrical resistance rapidly increased at 200°C. The time-temperature curve of the heating plate provided with this heating element is as shown in FIG. 3, and showed a constant temperature after a specific time.

As shown in Figure 4, a heating element (20 cm x 20 cm
m) with an insulating partition 8, for example, between X and A 9Q+90=]8Q Between X and B 18Ω+9Ω=27Ω Between X and -C 27Ω+9Ω=36Ω,
When 100V is applied to each of these, between X-A = 555W, between X-B = 370W, and between x-C = 278W (A, B, C, X, and Y are lead wires), making three-stage switching possible. As shown in FIG. 5, it is practical to save power by energizing X-A for the first 17 minutes and then switching to X-C. Also, if a pot or kettle is placed on the heating plate, the temperature will drop temporarily, and the temperature can be adjusted by switching to X-A or X--B depending on how the temperature drops.

That is, as shown in FIG. 3, since the resistance values of X-A, X-B, and XC are different, the time required to reach the maximum temperature is different, and this difference can be utilized.

The heating element 3 is covered with an insulating layer WI5, and this insulating layer has the same composition as the insulating layer 2 or is made of polyamide resin and SiO2, and has a thickness of 0.1~
IWl.

A heat insulating layer 6 is then provided which completely covers the insulating coated heating element 3. This is a low density ceramic heat insulating mat with a thickness of 1O-100n*n, preferably 3O-50na+.

When a kettle containing IQ water was placed on this heating plate (heating temperature 200°C) and the water was boiled, the IQ water boiled in 20 minutes.

Example 1 A mixture of 1.6 parts by weight of one-component polyepoxy resin (including 0.8 parts by weight of hardening agent) per 1 part by weight of spherical graphite with a diameter of 10 to 20 μm was applied. A heat insulating plate with a size of 30 an x 30 cm was obtained by the same operation as in Example 1, except that heat curing was carried out at °C for 5 hours to obtain an exothermic coating film 2IIWll.

As shown in FIG. 6, a heat insulating piece was placed on the coating surface 2 which had been heated to 40° C., and the temperature was measured at point A and point B under the heat insulating piece. Figure 7 is 0.05111att;/c+i
It is a graph showing the temperature difference between the temperature at point B and the temperature at point A of the heating element obtained from paint (,) and paint (b) with respect to the current application time with input power of f. With the heat insulating plate (a) of the present invention, there is only a rise of about 2°C (42°C) after 10 minutes, whereas with the heat insulating plate (a) of the present invention, there is a rise of only about 2°C (42°C) after 10 minutes.
In b), the temperature rose to about 45°C (85°C).

Also, when heat-curing at 120°C, the temperature is 47°C + 2°C (49°C
), and the conventional one is 47°C + 45°C (92°
C).

As the insulating layer of the metal plate, a thin Ni-Cr intermediate alloy layer is thermally sprayed and fixed, and then A1□03 ceramic is thermally sprayed and a conductive exothermic paint is applied at 70 to 300℃. A heating element (1
50°C, 300°C and 400°C). Experiments were conducted in which each of these devices was energized for a long period of time to generate heat, and was repeatedly switched on and off every 30 minutes, but there were no cracks or peeling accidents, and stable time-temperature curves were obtained for each.

Furthermore, when 30% polytitanocarbosilane is blended with spherical graphite, the resistance becomes 4Ω/hole at room temperature (approx. 8Ω/hole at 50%), and when 100V is applied to a 30cm square, it becomes 360℃ (280℃).
A surface temperature of 10°C was obtained.

As is clear from this, the heat insulating plate of the present invention does not cause local overheating, exhibits an automatic temperature control function, and can maintain a specific temperature without requiring any other means.

Since the heat retention or heating plate of the present invention is equipped with a heating element that can automatically control the temperature, it does not require a thermostat or the like like conventional heat retention or heating plates, that is, it does not require any other means. It can be said to be a novel thermal insulation or heating plate that is highly safe, inexpensive, and highly practical.

[Brief explanation of drawings]

Fig. 1 is a side cross-sectional view of the insulating or heating plate of the present invention, Fig. 2 is a temperature-resistance curve diagram of the insulating or heating plate of the present invention, and Fig. 3 is a time-temperature curve diagram of the insulating or heating plate of the present invention. , FIG. 4 is a state diagram of the heat-generating coating film with insulating partitions, and FIG. 5 is a diagram showing that the temperature of the heating plate of the present invention is adjusted by insulating partitions.
Fig. 6 is a schematic diagram showing the temperature measurement position for measuring the local overheating state when the insulation piece is placed, and Fig. 7 is a diagram showing the local overheating state of the heat insulation plate, where 1 is the board, 2 is the insulation layer,
3 is a heating element, 4 is an electrode terminal, 5 is an insulating layer, 6 is a heat insulating layer,
7 is a heat insulating piece, and D and E are temperature measurement points.

Claims (6)

[Claims] (1) An insulating layer is provided on the outside or bottom of the board, a heating element whose temperature can be automatically controlled is provided on the insulating layer, the heating element is covered with an insulating layer, and a heat insulating layer covers the entire heating element and insulating layer. A temperature-controllable heat retention or heating plate characterized by being provided with. (2) A conductive coating film in which a heating element whose temperature can be automatically controlled has an electrode terminal attached to an insulating layer, and a synthetic resin and carbon powder mainly containing particles consisting of spherical bodies with a particle size of 0.5 μm or more and 500 μm or less The insulation or heating plate according to claim 1, which is a heating element formed with. (3) A conductive coating film containing synthetic resin and carbon powder mainly containing particles consisting of spherical bodies with a particle diameter of 0.5 μm or more and 500 μm or less is applied to a substrate on which a heating element whose temperature can be automatically controlled is provided with an electrode terminal. 2. The heat retaining or heating plate according to claim 1, which is a heating element comprising a heating element. (4) The insulation or heating plate according to claim 1, wherein the substrate is made of a metal material. (5) The insulation or heating plate according to claim 1, wherein the insulating layer is made of a composition containing polyimide resin and Al_2O_3. (6) The insulation or heating plate according to claim 1, wherein the insulating layer is formed by thermally spraying Ni, Cr, Co, or an alloy thereof to form an intermediate layer, and then thermally spraying ceramics thereon.