KR100197201B1 - Sheet-like heating material - Google Patents

Abstract

The present invention relates to a planar heating element, in order to provide a new resistance heating element that is safe and excellent in plasticity and convenient to use. And a low molecular weight organic compound are formed by coating a thermosensitive element or a resistance heating element having a self-temperature control characteristic on a cloth-like base material.

By using such a planar heating element, even with repeated use, the change in resistance value is extremely small and has stable temperature and conduction characteristics, and there is no fear of local overheating, and it is a molecular level sensor that senses magnetic temperature at various stages. And it is possible to provide a planar heating element having a control function.

Description

Planar heating element

1 is a graph showing the relationship between the element surface temperature and the resistance value when the applied voltage of the planar heating element obtained in Example 1 is changed.

2 is a graph showing the temperature rising characteristic of FIG.

3 is a graph showing the temperature rise characteristic of the planar heating element similarly obtained in Example 2. FIG.

The present invention has a new resistance heat generation function that has a magnetic temperature control function in a low temperature region of about 100 ° C. or less, and does not require a complicated and incomplete temperature detection device and a safety fuse for preventing overheating. A surface heating element provided with an element.

Background Art Conventionally, conductive materials such as graphite, carbon black or metal powders are mixed with thermosetting resins or thermoplastic resins to form conductive resins or semiconductive resins, and they are widely used as electronic components or heating elements by utilizing excellent properties of these organic materials. However, their fatal drawback is that they lack stability and are not reliable. In particular, changes over time after long-term use could not be avoided.

For example, it has a stable temperature-conducting characteristic in a low temperature region of about 100 ° C. or less, and there is no change over time in the electrical resistance value even after repeated heating and cooling, and a large change in positive characteristic in a specific temperature detection and a specific temperature region There is a demand for the development of a resistance heating element having excellent stability having a magnetic temperature control function.

As a result of earnestly examining to solve the above problems, the present inventors have found that graphite or carbon black as a heat generating element of a self-temperature controlling plane heating element has a solid covalent bonding structure in the form of a two-dimensional typical hexagonal crystal plane, and the bonding force between the planar layers is improved. It is relatively loose and slips well, but has considerable adsorption force and exhibits insulation as interplanetary swelling, degeneracy, and so-called conjugated covalent bonds in two-dimensional planes, but between layers has the same conductivity as metal due to the presence of so-called π electron clouds. Part of the derivatives adsorbed by adsorbing derivatives having strong adsorption characteristics between the layers of graphite or carbon black by enlarging the interlayer distance while invading crystalline low molecular weight organic compounds between the upper and lower inorganic layers, Crosslinking by substituting the whole quantity or by adsorbing directly with the inorganic layer, and It reached to complete the present invention by finding that it is possible to freely control the resistance between the conductive layer by changing the molecular length of the bridge.

That is, the planar heating element of the present invention is a cloth (fabric) form of a thermosensitive element or a resistance heating element having a self-temperature control characteristic formed by combining a low dimensional material mainly composed of a crosslinked polymer and a linear polymer on graphite or carbon black. It is characterized by being coated on a base material.

The device of the planar heating element according to the present invention is composed of an organic solvent in which conductive monomer or carbon black is mixed with a monomer of a crosslinked polymer and a fine powder or a liquid polymer and a low molecular weight organic compound of a linear polymer compound which is a low dimensional material. The mixed and polymerized solution can be prepared by incorporating copper foil into a cotton fabric woven into a 1 mm gap of cotton # 20 twin yarns, for example, by coating or impregnating the embedded substrate with reaction drying.

Here, the liquid polymer refers to a liquid phase made of a high molecular weight polymer or a condensate molecule generated by repeating the same or similar reactions of a low molecular weight compound and having a viscous and dense liquid phase. As a substance to be shown, it is the same as a polymer by narrow discussion. These liquid polymers can be classified into naturally occurring natural polymers such as cellulose or protein and artificially made synthetic polymers such as polyethylene. Since proteins and nucleic acids are called biopolymers, they are not simple polymers. It is not usually called a polymer. In general, the properties of polymers are due to their high molecular weight and very large volume of molecules compared to low molecular systems. For example, polymers have a very large aggregation energy due to the aggregation energy of many atomic groups in the molecular chain. have. Therefore, the polymer (broad polymer) does not become a gas, and the molten polymer exhibits a viscous liquid phase.

The substrate of the planar heating element is not limited to a cotton woven fabric, and may be organic or inorganic, and its traits such as plate, film, linear, woven, nonwoven, dense, porous, etc. are not a problem. Do not. As long as it does not impair the self-temperature controllable conductivity characteristic.

In the present invention, graphite or carbon black may be natural or artificial graphite, furnace black, acetylene black, or the like, and it is preferable to use one having a particle diameter of 1 µm or less, particularly 0.1 µm or less.

As the crosslinking polymer, a monomer of a thermosetting resin which forms a three-dimensional network structure, for example, an epoxy resin, a melamine resin, a polyurethane resin, a silicone resin, and a modified resin thereof is suitably used.

Examples of the linear polymer compound include olefin polymers such as polyethylene, ethylene vinyl acetate copolymer, ethylene-vinyl chloride copolymer, polypropylene, ionomer resin, and the like, and fine powder polyethylene having crystallinity is preferable.

Moreover, as a typical example as a low molecular weight organic compound, C20 or more alkane type linear hydrocarbon or its fatty acid is mentioned.

As an organic solvent or reaction inducing agent, Aromatic hydrocarbons, such as benzene, toluene, and xylene, n-butanol; alcohols such as n-propanol; Ethylene glycol; Propylene glycol; Aliphatic glycols such as 1,4-butanediol; Alicyclic diols such as cyclopentane-1,2-diol; Phenols such as hydrokinone; Ketones such as methyl ethyl ketone; Tetrahydroplan etc. are mentioned.

When preparing a resistive heating element of a planar heating element having a self-temperature control characteristic of the present invention, the compound may be blended with 10 to 60 parts of graphite and 100 to 60 parts of conductive high dimensional material composed of graphite and a crosslinked polymer. Is preferably in the range of 40 to 90 parts.

If the crosslinked polymer exceeds 90 parts, the conductivity becomes poor. If it is less than 40 parts, that is, the weight effect is insufficient even if graphite exceeds 60 parts, the basic conductivity at room temperature varies depending on the type and amount of graphite or carbon black, but the specific temperature detection and magnetic temperature control characteristics are different. You may decide uniformly about. In addition, since the crosslinked polymer is also grafted with carbon black, it becomes a matrix (matrix) of the conductive material. Therefore, the basic conductivity varies, but may be determined uniformly.

In order to stabilize conductivity, the linear (chain) polymer compound is preferably added in the range of 5 to 100 parts with respect to 100 parts by adding the compounding amount of the crosslinking polymer and the compounding amount of graphite. When it exceeds 100 parts, conductivity falls extremely and exceeds practical range.

Low molecular organic compounds, for example, the hydrocarbon is in the range of 3 to 30 parts. If it exceeds 30 parts, toughness of a product will fall and the effect of a characteristic will become insufficient at 3 parts or less.

The organic solvent is required at least 25 parts or more, but may be optionally weighted as the solvent requires dilution.

In the planar heating element having the self-temperature control characteristic of the present invention, the crosslinking polymer monomer is first grafted with graphite, and the linear polymer compound is mixed with the monomer in the process of sequentially mixing with the compounding component. . Then, the polymer is mixed while twisting each other at the same time as the polymerization reaction of the crosslinked polymer in the heat treatment process. This is judged by the homogeneity of the device product. In addition, it plays a very important role with respect to the three-dimensionalization and degree of polymerization of the cross-linked polymer in order to give flexibility to the device product and to stabilize the properties.

In this way, the linear polymer compound gives flexibility and entropy stiffness to the three-dimensional network compound that is easily cured anyway, thereby giving flexibility at low temperatures, preventing loosening at high temperatures, and tightening to stabilize the entire system. have.

The low molecular organic compound can be seen to form an interlayer compound by directly invading between the graphite layers, invading between the graphite layers by a reaction inducing agent, or strongly adsorbing to the graphite layers.

This is because the planar heating element having the self-temperature control property of the present invention withstands repeated high temperature heating (low molecular weight organic compound is much higher than the melting point, for example, up to 130 ° C for a compound having a melting point of 65 ° C) and hardly changes its characteristics. Is not supported by the experimental results.

Hereinafter, the present invention will be described in detail with reference to Examples. In addition, the part of each component described in the following description represents a weight part.

Example 1

[Combination of self-temperature control conductive paint]

[Production of Test Piece of Magnetic Temperature Controlled Planar Heating Element]

As a resistivity-side application test piece, the above-mentioned compound solution was applied to a commercially available slide glass having a thickness of 1 mm x 76 mm x 26 mm with a roller at a thickness of about 20 µ, dried at room temperature, and cut off while leaving the coating film 10 mm wide. In addition, as a test piece for temperature-resistance characteristics and other characteristic tests, copper foil conductors were embedded in a cotton woven fabric of 1 mm2 of # 20 twin yarns, and embedded in a test piece base material cut to a width of 60 mm x an electrode length of 23 mm between electrodes. The above compound was impregnated, coated with two rollers (hardness 50 pressing pressure 1 kgf) of silicone rubber, and then dried at room temperature to obtain test pieces.

[Characteristic Test and Result]

The mixed solution obtained by the above formulation is a black juice, which is coated on each test piece substrate and irradiated with far-infrared rays to react the irradiated temperature at about 155 ° C. for 10 minutes to cause cracks on the surface of the coating film. Completed with nothing.

The specific resistance value of the test piece of the glass plate (glass base) was 8.5x10 <^-1> Pa-cm at 25 degreeC.

In addition, the test piece element of the cotton cloth substrate was alumina wool to keep the top and bottom of the element surface to apply a voltage. The device electrical resistance value immediately before voltage application was 13.0 KΩ and the device surface temperature was 25 DEG C. However, when AC 100V was applied, the resistance value increased proportionally to 16.8 KΩ as the temperature increased. Temperature reached 62 degreeC, hold | maintained this temperature for 8000 hours or more, and there was no temperature rise further.

Thereafter, when twice the power, ie, AC 141V, was applied to the same test pieces, the exothermic temperature was maintained at 75 ° C. for a long time, and there was no temperature increase at all. The resistance measurement of the device at this temperature rose to 23.4 KΩ.

In addition, the resistance of the device when the voltage application to the test piece device was cut off and restored to room temperature of 25.0 ° C. completely returned to 13.0 KΩ. Since this was repeated 12 times, the results were exactly the same as above, and it was confirmed that the device of the present formulation was a complete and stabilized temperature-dependent magnetic temperature control device.

FIG. 1 is a graph showing the relationship between the device surface temperature and the resistance value when the applied voltage to the test piece element obtained in this example is changed.

2 is similarly a graph showing the temperature rise characteristic, the horizontal axis represents time (minutes), and the vertical axis represents temperature (° C).

Example 2

[Combination of self-temperature control conductive paint]

[Production and Characteristic Test of Planar Heating Element Test Piece]

In the same manner as in Example 1, a planar heating element was produced by the above formulation. The specific resistance of the test pieces was 1.9 × 10 ⁻¹ dB-cm at 25 ° C. Moreover, the temperature rising characteristic is shown in FIG. Acrylic-epoxy resins have increased stability as the degree of polymerization of three-dimensional structuring advances, but on the other hand, they are very fragile (because of their fragility) as a planar heating element, which is a practical disadvantage. This defect is compensated for by ion-bonded ionomer resins.

Ionomer resins are thermoplastic elastomers (elastomers) that provide flexibility while maintaining stability in the device overall, especially at low temperatures close to room temperature. The compatibility with acryl-epoxy monomer is also very good and it mixes well.

As described above, according to the present invention, even after repeated use, the resistance value with very little change over time, stable temperature-conducting characteristics, and there is no fear of local overheating, and as a molecular level sensor, magnetic temperature detection and A planar heating element having a control function can be provided.

In addition, since the resistance heating element of the planar heating element has a property as a flexible elastomer having flexibility, abundant elasticity, and moderate rigidity even at elevated temperatures, it can be processed into various forms. It is easy and inexpensive to manufacture, so a wide range of applications is expected.

Claims (1)

A thermosensitive element or a resistance heating element having a self-temperature control characteristic is formed by mixing a crosslinked polymer monomer, a fine polymer of a linear polymer compound, or a liquid polymer and a low molecular weight organic compound, with conductive graphite or carbon black. A planar heating element, which is formed by coating a substrate.