JPH10310698A - Conductive surface heated composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a surface heater composition usable at a high temp. by adding conductive particles to a solvent-soluble block polyimide resin prepd. by the polycondensation of an arom. diamine and a tetracarboxylic dianhydride in the presence of a catalyst comprising a lactone and a base. SOLUTION: The arom. Diamine for producing the block polyimide resin is selected from among 1,4-benzenediamine, 2,2-bis[4-(4-aminophenoxy) phenyl]propane, diaminosiloxane, etc. The tetracarboxylic dianhydride is selected from among biphenyltetracarboxylic dianhydride, benzophenonetetracarboxylic dianhydride, etc. A metal powder, graphite, and a carbon black are examples of the conductive particles. The particles are added to an org. polar solvent soln. contg. 10-40 wt.% block polyimide resin to give a high-viscosity conductive paste, which is uniformly applied to a heat-resistant insulating substrate having printed electrodes formed thereon for sending an electric current and dried to give the conductive surface heater.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive sheet heating element composition having stable electric characteristics at a high temperature, and more particularly to a conductive sheet heating element composition which can be used as a heating element of electric appliances.

[0002]

2. Description of the Related Art Conventionally, it has been known to mix a conductive powder with a synthetic resin or the like to obtain a conductive planar heating element composition. Examples of this type of planar heating element include, for example, a conductive planar heating element composition in which a resin component is polyethylene resin, polypropylene resin, polyester resin, or silicone resin, and conductive carbon black or graphite is kneaded as a conductive particle component. An object configured as an object is known (Japanese Patent Laid-Open No. 6-215907).

[0003]

However, in the above-mentioned conductive sheet heating element, the upper limit of the practical heat-resistant temperature of the resin constituting the conductive sheet heating element is, for example, polyethylene resin. Since it is about 90 ° C. and about 110 ° C. even in the case of polyester resin,
In the case of a sheet heating element made of such a resin component, the use temperature range is limited to a temperature lower than or equal to the upper limit temperature, and thus the use of an electric appliance equipped with the sheet heating element is limited. An object of the present invention is to provide a sheet heating element which can be used at a high temperature by improving the conventional sheet heating element having these problems.

[0004]

DISCLOSURE OF THE INVENTION The conductive sheet heating element of the present invention has solved the above-mentioned problems, and uses a block copolymer polyimide having heat resistance at a high temperature as a matrix resin component. It is characterized by:

[0005] Polyimide does not lose its flexibility even at an extremely low temperature of -200 ° C, has a decomposition onset temperature of 500 ° C or higher and can be used for a long time at a high temperature, and is widely used in the electronics field.

However, conventional polyimides must be processed with a polyamic acid and are difficult to dissolve in a solvent, so that molding and screen printing are difficult.
There was a problem in using it as a sheet heating element. The polyimide of the present invention is a block copolymerized polyimide, and the properties of the polymer required for the sheet heating element can be changed by selecting a copolymerized component of the block polyimide. For example, by introducing an adhesive group, the affinity and adhesion to metal particles and carbon particles can be increased (US Pat. No. 5,502,143).

The heat-resistant sheet heating element of the present invention is:
A conductive sheet heating element composition comprising a polyimide resin component obtained by polycondensing an aromatic diamine and a tetracarboxylic dianhydride in the presence of a catalyst comprising a lactone and a base, and a conductive particle component.

In the present invention, the polyimide resin is a conductive sheet heating element composition comprising a solvent-soluble block polyimide resin component obtained by a sequential reaction and a conductive particle component.

Further, the aromatic diamine of the block polyimide resin component is 1,4-benzenediamine, 1,3-benzenediamine, 6-methyl-1,3-benzenediamine,
4,4'-diamino-3,3'dimethoxy-1,1'-
Biphenyl, 4,4'-methylenebis (benzeneamine), 4,4'-oxybis (benzeneamine), 3,
4′-oxybis (benzeneamine), 4,4′-thiobis (benzeneamine), 4,4′-sulfonyl (benzeneamine), 3,3′-sulfonyl (benzeneamine), 1-methylethylidine 4,4 '-Bis (benzeneamine), 1-trifluoromethyl 2,2,2 trifluoroethylidine 4,4'-bis (benzeneamine),
4,4′-diaminobenzanilide, 3,5-diaminobenzoic acid, 2,6-diaminopyridine, 2,2bis (4
(4-aminophenoxy) phenyl) propane, 2,2
Bis (4 (4-aminophenoxy) phenyl) sulfone, 1,4-bis (4-aminophenoxy) benzene,
It comprises at least one component selected from 1,3-bis (3-aminophenoxy) benzene, diaminosiloxane and 9,9′-bis (4-aminophenyl) fluorene, and the tetracarboxylic dianhydride is Biphenyltetracarboxylic dianhydride, benzophenonetetracarboxylic dianhydride, 4,4 ′-(2,2,2-trifluoro-
1- (trifluoromethyl) ethylidene) bis (1,2
-Benzenetetracarboxylic dianhydride, bis (dicarboxyphenyl) ether dianhydride, pyromellitic dianhydride, naphthaletetracarboxylic dianhydride, bicyclo (2,2,2) -oct-7-ene -2, 3, 5, 6-
The above-mentioned conductive sheet heating element composition comprising at least one component selected from tetracarboxylic dianhydrides.

The conductive particle component may be at least one selected from metal powder, metal fiber, graphite, carbon black, carbon fiber, and metal oxide, or a mixture thereof. Is a conductive sheet heating element composition. As these conductive particles, 1
Those having a particle size of -100 millimicrons are preferred. These conductive particle components are contained in a mixing ratio suitable for achieving the desired resistivity of the intended conductive planar heating element composition, usually 10 to 80% by weight based on the resin composition, and more preferably. And 30 to 60% by weight of the resin composition. In addition, it is also possible to mix additives and pigment components which do not have conductivity by themselves into the conductive particle component depending on the required characteristics of the product in some cases.
As these additives and pigment particle components, an inert stabilizer,
Antioxidants, dispersants and the like are included. These additives and pigment particle components are usually used in a considerably smaller mixing amount than the conductive particle components. As these additives and pigment particle components, fine particles of alumina, silica, titanium oxide, magnesium oxide and the like are used.

In the polymerization reaction of the block copolymerized polyimide of the present invention, an organic polar solvent is used, and these solvents include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, Tetramethylurea, dimethylsulfoxide, sulfolane, tetrahydrofuran and the like are used alone or as a mixture.

In the polymerization reaction of the block copolymerized polyimide of the present invention, a catalyst for accelerating the polymerization reaction is used. As the catalyst system, valerolactone as an acid catalyst,
A combination of pyridine, methylmorpholine and the like as a base catalyst is used. Water generated by the imidization reaction during the reaction is removed from the reaction system as an azeotrope with xylene, toluene and the like.

The conductive sheet heating element composition of the present invention is usually prepared by adding a necessary amount of conductive particles and / or a polymer solution containing an organic polar solvent containing (10-40)% by weight of a block copolymerized polyimide. , Additives and pigment particle components are sufficiently mixed to form a uniform, high-viscosity paste. The high-viscosity paste composition in a uniform state is preliminarily printed on a heat-resistant insulating substrate by a printed circuit of a copper wire, a silver wire, a nickel wire, or a conductive ink so that necessary electricity can be supplied to the heating element. A coating is formed on the designed electrode by directly applying it uniformly or by applying it uniformly by screen printing.

According to the present invention, the organic polar solvent in the high-viscosity paste composition uniformly coated on the substrate having the electrodes is evaporated and dried using a hot air drier, an infrared drier or the like. Can be obtained. As the heat-resistant insulating substrate of the conductive planar heating element composition of the present invention, a polyimide film, synthetic mica, ceramic, glass cloth, or the like is used.

Further, by applying the above-mentioned uniform high-viscosity paste composition directly to the insulated surface of an electric appliance instead of the heat-resistant insulating substrate, the sheet heating element of the present invention can be obtained. It is possible.

[0016]

According to the conductive sheet heating element composition of the present invention, the block copolymer polyimide which is a resin component constituting the sheet heating element has extremely high heat resistance, so that it cannot be reached with conventional resin components. Not only can the temperature of the heating element be raised up to a high temperature range in the temperature range, but there is no burning during abnormal heating. Therefore, an electric appliance to which the planar heating element of the present invention is applied can be used at a high temperature.

[0017]

【Example】

Example 1 A 2 L separable three-necked flask equipped with a stainless steel anchor stirrer is fitted with a cooling tube with a ball equipped with a moisture separation trap. Heating and stirring while passing nitrogen gas, 3,4,3 ′, 4′-benzophenonetetracarboxylic dianhydride 116.0 g (0.36 mol),
21.99 g (0.18 mol) of 4-diaminotoluene,
5.4 g (0.054 mol) of γ-valerolactone, 8.5 g (0.1 mol) of pyridine, 400 g of N-methylpyrrolidone and 50 g of toluene are charged. After stirring at room temperature under a nitrogen atmosphere at 200 rpm × 30 minutes, the temperature was raised to 180 ° C., and the mixture was stirred at 200 rpm for 1 hour. After air cooling, 15 g of an azeotropic content of toluene-water is removed. Add bis (3
-Aminophenoxy) -4,4'-diphenylsulfone 77.85 g (0.18 mol), N-methylpyrrolidone 74 g and toluene 60 g are added. After stirring for 1 hour at room temperature under a nitrogen atmosphere, the temperature was increased to 180 ° C., and 200 rpm
For 3.5 hours. During this time, the azeotropic content of toluene-water was removed. The polymer concentration of the polyimide solution thus obtained was 30% by weight. This reaction solution was N-
Upon diluting the polymer concentration with methylpyrrolidone at 15% by weight, the solution viscosity was 470 centipoise at room temperature on a bubble viscometer. Further, when the molecular weight of this polymer was measured by high performance liquid chromatography, the number average molecular weight (Mn) was 27,000 in terms of styrene, the weight average molecular weight (Mw) was 67,800, and Mw / Mn =
It was 2.51. This polyimide was poured into methanol to make a powder and subjected to thermal analysis. The glass transition temperature (Tg) is
266-284 ° C, and decomposition initiation temperature was 522 ° C.

For 100 parts by weight of the reaction solution (block copolymerized polyimide solution) (C), 1 part of carbon black (Denka Black, manufactured by Denki Kagaku Kogyo Co., Ltd.) and one part of graphite (Graphite CSSP / product of Nippon Graphite Industry Co., Ltd.) Twenty parts by weight of the conductive particles having a mixing ratio of 1: 1 were sufficiently kneaded to prepare a uniform conductive paste.

The above-mentioned conductive paste is applied to a polyimide film (Kapton / Toray Dupont Co., Ltd.) whose electrodes are previously formed with silver conductive ink by a screen printing method to a thickness of 25 μm (solid content). Standard), and then apply 180 in an infrared dryer.
By drying at 20 ° C. for 20 minutes, a flexible sheet heating element was obtained.

The resistance of the conductive sheet heating element composition is 2
By applying an alternating current of 100 V to the electrodes at 00 ohms, the surface temperature of this conductive sheet heating element is 362 ° C.
(Measured with an infrared thermometer). The energization was continued for 3 hours, and it was confirmed that the surface temperature was stable. Thereafter, the energization was stopped, and one hour later, the energization was performed again for 2 hours under the above conditions, the surface temperature of the conductive sheet heating element was measured, and the same experiment was repeated for 500 hours. It was 2 ohms. Measure the surface temperature of this conductive sheet heating element, 365 ° C (measured with an infrared thermometer)
At room temperature. Further, it was confirmed that the surface temperature was stable in the above-mentioned state during energization.

Embodiment 2 This is the same as Embodiment 1. The mixture was heated and stirred while passing a nitrogen gas, and 64.45 g (0.2 mol) of 3,4,3 ′, 4′-benzophenonetetracarboxylic dianhydride was 12.22 g (0.1 mol) of 2,4-diaminotoluene. ), 3.0 g (0.03 mol) of γ-valerolactone and pyridine 4.
0 g (0.05 mol), N-methylpyrrolidone 400
g and 50 g of toluene. 2 at room temperature under nitrogen atmosphere
After stirring at 00 rpm × 30 minutes, the temperature was raised to 180 ° C.
The mixture was stirred at 00 rpm for 1 hour. After air cooling, 15 g of an azeotropic content of toluene-water is removed. In the above reaction solution, bicyclo (2,
2,2) -Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride 24.82 g (0.1 mol), bis (3-aminophenoxy) -4,4-diphenylsulfone 86 .5 g (0.2 mol), N-methylpyrrolidone 3
09 g and 50 g of toluene are charged. After stirring at room temperature under a nitrogen atmosphere at 200 rpm × 30 minutes, the temperature was raised to 180 ° C., and the mixture was stirred at 200 rpm for 3 hours. During this time, the azeotropic content of toluene-water was removed. This polyimide was poured into methanol to make a powder and subjected to thermal analysis. Glass transition temperature (Tg)
Was 263-272 ° C, and the decomposition initiation temperature was 470 ° C.

With respect to 100 parts by weight of this reaction solution (block copolymerized polyimide solution), carbon black (Denka Black, manufactured by Denki Kagaku Kogyo Co., Ltd.) and graphite (Graphite CSSP, manufactured by Nippon Graphite Industry Co., Ltd.)
Of the conductive particles in a mixing ratio of 1: 1.2 was sufficiently kneaded to prepare a uniform conductive paste.

The conductive paste was applied to a polyimide film (Kapton / Toray Dupont Co., Ltd.) whose electrodes were previously formed with silver conductive ink by a screen printing method to a thickness of 25 μm (based on solid content). ), And then apply 180 in an infrared dryer.
By drying at 20 ° C. for 20 minutes, a flexible conductive sheet heating element composition having a resistance value of 200 ohms was obtained.

By applying an AC voltage of 100 V to the sheet heating element, the surface temperature of the sheet heating element becomes 3
20 ° C. (measured with an infrared thermometer). The time-dependent change in the resistance value was measured in the same manner as in Example 1. After confirming that the surface temperature was stable, the resistance value of the conductive planar heating element was measured and confirmed to be 197.5 ohms.

Embodiment 3 This is the same as Embodiment 1. The mixture was heated and stirred while passing nitrogen gas, and 21.81 g (0.1 mol) of pyromellitic dianhydride and 44 g (0.0) of diaminosilane (molecular weight: 880) were used.
5 g), 2.0 g (0.02 mol) of γ-valerolactone, 2.4 g (0.022 mol) of pyridine, 250 g of N-methylpyrrolidone, and 80 g of toluene. After stirring at room temperature under a nitrogen atmosphere at 200 rpm for 30 minutes,
The temperature was raised to 180 ° C., and the mixture was stirred at 200 rpm for 1 hour. After air cooling, 15 g of an azeotropic content of toluene-water is removed. To the reaction solution, 32.22 g (0.1 mol) of 3,4,3 ′, 4′benzophenonetetracarboxylic dianhydride, 15.22 g (0.1 mol) of 3,5-diaminobenzoic acid, bis ( 3
-Aminophenoxy) -biphenylsulfone 21.63
g, N-methylpyrrolidone 261 g and toluene 50 g. After stirring at room temperature under a nitrogen atmosphere at 200 rpm × 30 minutes, the temperature was raised to 180 ° C., and the mixture was stirred at 200 rpm for 4 hours. During this time, the azeotropic content of toluene-water was removed. This polyimide was poured into methanol to make a powder and subjected to thermal analysis. The glass transition temperature (Tg) was 275 ° C., and the decomposition starting temperature was 475 ° C.

With respect to 100 parts by weight of this reaction solution (block copolymerized polyimide solution), carbon black (Denka Black, manufactured by Denki Kagaku Kogyo Co., Ltd.) and graphite (Graphite CSSP, manufactured by Nippon Graphite Industry Co., Ltd.)
Was mixed sufficiently with 20 parts by weight of conductive particles having a mixing ratio of 1: 1.1 to prepare a uniform conductive paste.

The above-mentioned conductive paste was applied to a 25 μm paste (based on solid content) on a polyimide film (product of Kapton / Toray Dupont Co., Ltd.) in which electrodes were previously formed with silver conductive ink by screen printing. ), And apply it in an infrared dryer.
By drying at 80 ° C. for 20 minutes, a flexible conductive sheet heating element composition was obtained.

The electrode of the conductive sheet heating element composition is
By applying an AC voltage of 00 V, the surface temperature of the conductive sheet heating element became 333 ° C. (measured with an infrared thermometer). Continue energizing for 3 hours,
It was confirmed that the surface temperature was stable. Thereafter, the energization was stopped, and after one hour, the energization was performed again under the above conditions, and the surface temperature of the conductive sheet heating element was measured. The same experiment was repeated three times. I confirmed that.

[0029]

As described above, according to the present invention, it is possible to prepare a flexible conductive sheet heating element composition which can be used at a high temperature by using a block copolymerized polyimide as a resin component. The present invention can be widely used in fields such as electric appliances which conventionally used a nichrome wire as a heating element.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H05B 3/12 H05B 3/12 A 3/14 3/14 A FG 3/20 373 3/20 373

Claims (4)

[Claims] 1. A conductive sheet heating element composition comprising a polyimide resin component obtained by polycondensing an aromatic diamine and a tetracarboxylic dianhydride in the presence of a catalyst comprising a lactone and a base, and a conductive particle component. 2. A conductive sheet heating element composition comprising a solvent-soluble block polyimide resin component obtained by a sequential reaction of the polyimide resin of claim 1 and a conductive particle component. 3. An aromatic diamine of a block polyimide resin component is 1,4-benzenediamine, 1,3-benzenediamine, 6-methyl-1,3-benzenediamine, 4,4
'-Diamino-3,3'dimethoxy-1,1'-biphenyl, 4,4'-methylenebis (benzeneamine),
4,4′-oxybis (benzeneamine), 3,4′-
Oxybis (benzeneamine), 4,4′-thiobis (benzeneamine), 4,4′-sulfonyl (benzeneamine), 3,3′-sulfonyl (benzeneamine),
1-methylethylidine 4,4′-bis (benzeneamine), 1-trifluoromethyl 2,2,2 trifluoroethylidine 4,4′-bis (benzeneamine) 4,
4'-diaminobenzanilide, 3,5-diaminobenzoic acid, 2,6-diaminopyridine, 2,2bis (4 (4
-Aminophenoxy) phenyl) propane, 2,2bis (4 (4-aminophenoxy) phenyl) sulfone,
1,4-bis (4-aminophenoxy) benzene, 1,
3-bis (3-aminophenoxy) benzene, diaminosiloxane, 9,9′-bis (4-aminophenyl) fluorene and at least one component selected from tetracarboxylic dianhydride and biphenyltetra Carboxylic acid dianhydride, benzophenonetetracarboxylic acid dianhydride, 4,4 ′-(2,2,2-trifluoro-1-
(Trifluoromethyl) ethylidene) bis (1,2-benzenetetracarboxylic dianhydride, bis (dicarboxyphenyl) ether dianhydride, pyromellitic dianhydride, naphthaletetracarboxylic dianhydride, bicyclo ( 2,2,2) -Oct-7-ene-2,3,5,6-
The conductive sheet heating element composition according to claim 1, comprising at least one component selected from tetracarboxylic dianhydrides. 4. The conductive particle component comprises metal powder, metal fiber, graphite, carbon black, carbon fiber,
The conductive sheet heating element composition according to claim 1, wherein the composition comprises at least one component selected from metal oxides or a mixture thereof.