JP2005347650A - Ptc (positive temperature coefficient) efficiency reinforcement agent and macromolecular ptc composition added by it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a PTC efficiency agent, which indicates a big resistance change because of a rapid rising of PTC characteristic, and has a low resistance at normal temperature, furthermore can obtain a stable PTC composition of the PTC characteristic after repeat switching operation, a PTC composition using it and a PTC heating element. <P>SOLUTION: The PTC efficiency agent mainly consisting of a fatty acid amide, a macromolecular PTC composition characterized by containing the PTC efficiency reinforcement agent, and the PTC heating element which are characterized in that the fatty acid amide is one kind or two kinds or more from among a stearic acid amide, an oleic acid amide, a lauric acid amide, a palmitic acid amide, an erucic acid amide, a behen acid amide, an ethylene bisstearic acid amide, an ethylene bislauric acid amide, an N-oleic palmit amide, and a N-stearyl erucic amide. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a PTC efficiency enhancer that increases the PTC efficiency of a conductive composition having PTC (Positive Temperature Coefficient), a PTC composition using the PTC efficiency enhancer, and a PTC planar heating element. The present invention further relates to a method for enhancing PTC efficiency using the PTC efficiency enhancer.

Conventionally, as a composition having PTC characteristics, an inorganic conductive composition (ceramic PTC composition) such as barium titanate (BaTiO ₃ ) doped with a small amount of oxide to make a semiconductor, or a highly crystalline composition such as polyethylene An organic conductive composition (polymer PTC composition) in which a powder such as carbon black having conductivity in molecules is kneaded is known. Here, the PTC composition has a resistance value R inherent to the material and a current value I applied to the element, and generates heat by so-called Joule heat heating (I ² R heating). Therefore, the PTC composition is relatively large in the PTC composition. When current flows, heat is generated and the resistance value increases.
These PTC compositions generate heat when electricity flows and can be used as a heater.

For example, as a heater using a polymer PTC composition, JP-A-7-335378 discloses a PTC composition comprising an amorphous polymer, a conductive filler, and crystalline polymer particles that are incompatible with the amorphous polymer. A method for producing a PTC heating element is disclosed, in which a paste in which an object is dispersed in an organic solvent is applied on a flexible circuit board film provided with a metal foil as a conductive layer and dried.
JP-A-8-120182 discloses a PTC composition comprising an amorphous polymer, crystalline polymer particles incompatible with the amorphous polymer, conductive carbon black, graphite and an inorganic filler, and the PTC. A planar heating element is disclosed in which a crosslinked product of the composition is disposed on a conductive layer formed on a resin film substrate.
Furthermore, Japanese Patent Application Laid-Open No. 2003-109803 discloses a flexible PTC planar heating element and a method for manufacturing the same. The PTC planar heating element includes a flexible porous body, a pair of flexible electrodes disposed at a distance from the flexible porous body, and a pair of flexible electrodes electrically connected to the pair of flexible electrodes. It consists of the flexible PTC resistor provided by connection and the flexible coating material which covers these, and the flexible electrode and the flexible PTC resistor are formed by screen printing.

  It is said that the PTC characteristic of a polymer composition is basically expressed by the following mechanism. That is, at a temperature lower than the crystal melting point of the polymer component of the composition, since the conductive particles dispersed in the amorphous region of the polymer component are in contact with each other, a conductive route is formed and exhibits low resistance. As the temperature rises, the crystalline region of the polymer component dissolves, the volume of the amorphous region increases, and the distance between the conductive particles increases, so that the conductive route is cut and high resistance is exhibited. And when the temperature of the said composition falls to normal temperature, since the distance between particle | grains of electroconductive particle approaches again by the reduction | decrease of the volume of the amorphous area | region of a polymer component, a conductive route is re-formed and it becomes low resistance.

  As performance required as a PTC composition, the rise of the PTC characteristic is abrupt and shows a large resistance change, the resistance at normal temperature is small, the characteristic stability after repeated switching operation, in particular, the resistance does not change, Etc. This is because, as a characteristic of PTC heaters, etc., the rate of temperature rise after switching on is fast, and when the temperature rises above a certain level, the resistance suddenly rises and the energization stops automatically. This is because it is necessary to prevent accidents. Furthermore, these PTC characteristics are required to remain unchanged after repeated energization.

In order to achieve these objectives, the following reports have been made.
For example, International Publication No. WO01 / 057889 shows PTC behavior at a relatively low temperature, is sensitive to PTC behavior and is excellent in repeated stability of PTC behavior, has no fluidity even after temperature rise, and PTC A conductive polymer composition in which 5 to 150 parts by weight of a conductive powder is dispersed in 100 parts by weight of a crystalline polymer for the purpose of providing a composition having a temperature range that exhibits high resistance as an element, Conductive polymer composition having PTC characteristics, characterized in that the crystalline polymer undergoes crystal transition, and trans-1,4-polybutadiene having 85% or more of trans-1,4 bonds in the crystalline polymer A conductive polymer composition is disclosed.

  In JP-A-10-116702, 550 to 1000 parts by weight of titanium carbide powder having an average particle diameter of 0.1 to 5 μm is blended with 100 parts by weight of crystalline polymer, and the titanium carbide powder is silane. Disclosed is a PTC composition characterized by being surface treated with a compound coupling agent.

However, according to the invention described in International Publication No. WO01 / 057889, the polymer in the composition must be limited to a specific type, and various types of polymer PTC compositions that are currently widely used. However, there was a drawback that the polymer cannot be used. In addition, according to the invention described in Japanese Patent Application Laid-Open No. 10-116702, there is a problem that it takes time and cost for surface treatment of titanium carbide powder with a silane compound coupling agent, resulting in poor productivity.
International Publication WO01 / 057889 JP-A-10-116702

  As a result of intensive studies to solve the above problems, the present inventors have found that when a certain compound is added to a PTC composition as a PTC efficiency enhancer, the PTC performance is greatly improved. It was.

The PTC efficiency enhancer according to claim 1 of the present invention is a polymer PTC composition having a crystalline polymer and a conductive powder, which is added to the polymer PTC composition to increase the PTC efficiency. An enhancer, characterized by comprising a fatty acid amide as a main component.
As described in claim 2, the fatty acid amide is stearic acid amide, oleic acid amide, lauric acid amide, palmitic acid amide, erucic acid amide, behenic acid amide, ethylene bis stearic acid amide, ethylene bis lauric acid amide, One or more of N-oleyl palmitoamide and N-stearyl erucamide are characterized.
The polymer PTC composition of the present invention is characterized in that, in the polymer PTC composition having a crystalline polymer and a conductive powder, the polymer PTC composition of the present invention contains the PTC efficiency enhancer. To do.
Furthermore, as described in claim 4, the PTC heating element of the present invention is characterized by using a polymer PTC composition containing the PTC efficiency enhancer.
According to a fifth aspect of the present invention, there is provided a method for enhancing the PTC efficiency of the present invention by adding a fatty acid amide to a polymer PTC composition having a crystalline polymer and a conductive powder. It is characterized by enhancing the PTC efficiency of the product.

  According to the present invention, when a PTC efficiency enhancer mainly composed of a fatty acid amide or the like is added to the PTC composition, the PTC efficiency of the carbon-polymer PTC composition can be remarkably increased. That is, when the PTC efficiency enhancer of the present invention is added to the polymer PTC composition, the rise of the PTC characteristic is abrupt and shows a large resistance change, the ascending / descending cycle is almost the same path, the resistance at room temperature is small, and it is repeated. A PTC composition having stable PTC characteristics after the switching operation can be obtained. Furthermore, the PTC heating element which consists of a PTC composition which added the PTC efficiency enhancer of this invention can be made into the suitable thing which has the said characteristic.

(PTC efficiency enhancer)
As the PTC efficiency enhancer of the present invention, fatty acid amide can be mainly used.
As the fatty acid amides, aliphatic monoamides and aliphatic bisamides are suitable. Specifically, lauric acid amide, palmitic acid amide, oleic acid amide, stearic acid amide, behenic acid amide, erucic acid amide, N-oleyl palmi Toamide, N-stearyl erucamide, N-palmityl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl-12-hydroxystearic acid amide, N-oleyl-12-hydroxystearic acid amide, N-methylol stearin Acid amide, N-methylol behenic acid amide, methylene bis stearic acid amide, methylene bis lauric acid amide, methylene bis (12-hydroxystearic acid amide), ethylene biscapric acid amide, ethylene bis lauric acid amide, ethyl Bisstearic acid amide, ethylene bisisostearic acid amide, ethylene bis (12-hydroxystearic acid amide), ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene bis ( 12-hydroxystearic acid amide), butylene bis stearic acid amide, methylene bis oleic acid amide, ethylene bis oleic acid amide, ethylene bis erucic acid amide, hexamethylene bis oleic acid amide, 1,3-xylylene bis stearic acid amide, N-butyl-N′-stearyl urea, N-phenyl-N′-stearyl urea, N, N′-distearyl urea and the like can be mentioned.
As the aliphatic amide compound, stearic acid amide, oleic acid amide, lauric acid amide, palmitic acid amide, erucic acid amide, behenic acid amide, ethylene bis stearic acid amide, ethylene bis lauric acid amide, N-oleyl palmitoamide, N -Stearyl erucamide is preferable, and stearic acid amide and ethylenebisstearic acid amide are more preferable.

  The reason why the fatty acid amide improves the PTC characteristics is not clear at present, but the fatty acid amide has a relatively high molecular weight and a small degree of freedom between molecules. It is considered that the dense state and the state where the contact of the conductive particles deteriorates can be reversibly repeated.

  Various other additives can also be added to the PTC efficiency enhancer of the present invention. Examples of the additive include a coupling agent; a flame retardant such as an antimony compound, a phosphorus compound, a chlorine compound, and a bromine compound; an antioxidant; and a stabilizer.

<PTC composition>
The PTC composition of the present invention is a polymer PTC composition comprising a crystalline polymer and a conductive powder, and is characterized by containing the PTC efficiency enhancer.

As the crystalline polymer used in the PTC composition of the present invention, any polymer can be used as long as it can adhere to the base material and retain the conductive substance.
Specific examples include polyolefin, polyester, polyamide, polyurethane, polyether, polycarbonate, polyacetal, polysulfone, polyvinyl chloride, fluororesin, polyalkylene oxide, and polyphenylene oxide.
It is desirable to use polyolefin, polyester, polyamide, polyurethane, fluororesin, etc. in order to flexibly cope with external pressure such as bending, bending, and pressurization.

Examples of the polyolefin include polyethylene, polybutadiene, polyethylene acrylate, polypropylene, polystyrene, chlorinated polyethylene, chlorosulfonated ethylene, polyfluorinated ethylene, and styrene-acrylonitrile copolymer.
Examples of the polyalkylene oxide include polyethylene oxide.
Polyurethane is preferable because it is composed of a polymer of a hard segment and a soft segment, so that a composition suitable for the intended use can be obtained.

Examples of the polyester include polyethylene terephthalate and polybutylene terephthalate. As the other polyester, a general crystalline polyester containing an alcohol component composed of a divalent or higher polyhydric alcohol and a carboxylic acid component composed of a divalent or higher polyvalent carboxylic acid compound can be used. It is preferable to use a diol having 2 to 6 carbon atoms for the alcohol component and fumaric acid for the carboxylic acid component.
Other alcohol components include 1,4-butanediol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4-butenediol, , 2-pentanediol and other C2-C6 diols, and condensates of C2-C6 diols, diethylene glycol, triethylene glycol, 1,8-octanediol, 1,4-cyclohexanedimethanol, dipropylene C7-20 aliphatic diols such as glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, hydrogenated bisphenol A, and their condensates, sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentae Thritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerin, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, tri Examples thereof include trihydric or higher polyhydric alcohols such as methylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.
As carboxylic acid components that can be used in addition to fumaric acid, maleic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, Azelaic acid, malonic acid, succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or alkenyl group having 2 to 20 carbon atoms such as dodecenyl succinic acid and octyl succinic acid, and anhydrides and alkyl esters of these acids, etc. Divalent carboxylic acid compounds such as derivatives, 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4- Butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2 Methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, empor trimer acid and their Examples thereof include trivalent or higher carboxylic acid compounds such as acid anhydrides and derivatives such as alkyl esters.
The weight average molecular weight of the polyester is preferably in the range of 3 to 80,000.

Polyamides include polymers and copolymers obtained from ε-caprolactam, 6-aminocaproic acid, ω-enantolactam, 7-aminoheptanoic acid, 11-aminoundecanoic acid, 9-aminononanoic acid, α-pyrrolidone, α-piperidone and the like. A polymer is mentioned.
For example, nylon 6 by ring-opening polymerization of ε-caprolactam, nylon 66 by condensation polymerization of hexanemethylenediamine and sebacic acid, nylon 610 by condensation polymerization of hexanemethylenediamine and sebacic acid, ring-opening polymerization of ω-laurolactam or 12-aminododecane Examples thereof include nylon 12 by acid, and copolymer nylon having two or more components as described above.
Moreover, nylon MXD6 which is a crystalline thermoplastic polymer obtained from metaxylenediamine (MXDA) and adipic acid is mentioned. Furthermore, nylon 46 obtained from 1,4-diamine butane and adipic acid is mentioned. Further, methoxymethylated polyamide in which hydrogen of amide bond of nylon resin is substituted with methoxymethyl group can be mentioned. Furthermore, aromatic polyamide obtained from terephthalic acid and paraphenylenediamine can also be mentioned.
The molecular weight of the polyamide is not particularly limited, but those having an average molecular weight of 8,000 to 50,000, particularly 10,000 to 30,000 are preferred.

  The above polymers can be used alone or as a blend polymer in which at least one selected from these is mixed. The type and composition ratio of the polymer can be appropriately selected according to the desired performance and application.

  The crystalline polymer may be not only a homopolymer or a blend polymer but also a block copolymer having a crystalline block. Specifically, ethylene-acrylic acid copolymer having ethylene as a crystalline block, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer Polymer, ethylene-acrylic acid ester-maleic anhydride copolymer, ethylene-octene copolymer, ethylene-glycidyl methacrylate copolymer, ethylene-vinyl acetate copolymer ketone compound, fluorinated ethylene-propylene copolymer, etc. And amide-ester copolymers having polyamide as a crystalline block.

  These polymers preferably have a softening point of 30 to 150 ° C. and higher than a set switching temperature. When the softening point is lower than the above range, the heat resistance is inferior. When the softening point is higher than the above temperature, the PTC characteristic is inferior. The softening point is measured by a differential scanning calorimeter (DSC).

The conductive powder includes carbon fine particles such as graphite, carbon black, and carbon whisker, metal fine particles such as metal powder and metal foil, and synthetic resin fine particles such as potassium titanate, mica, acrylic resin, and melamine resin. Alternatively, conductive fine particles surface-treated with a metal can be used. The particle size of the conductive powder is generally preferably in the range of 0.010 to 50 μm.
The addition amount of the conductive powder is set in the range of 30 to 150 parts by weight with respect to 100 parts by weight of the polymer component. By adjusting the addition amount in the above range, the planar heating element The switching temperature can be adjusted as appropriate. If the blending amount of the conductive powder is lower than 30 parts by weight, heat generation cannot be sufficiently performed, while if it is higher than 150 parts by weight, desired PTC characteristics cannot be expressed.

  In the PTC composition of the present invention, the addition amount of the PTC efficiency enhancer is in the range of 0.4 to 50 parts by weight, preferably 0.4 to 30 parts by weight with respect to 100 parts by weight of the polymer component. It is preferable to be in the range. When the blending amount of the PTC efficiency enhancer is lower than 0.4 parts by weight, the effect as the PTC enhancer of the present invention cannot be sufficiently exhibited.

(Method for producing PTC composition)
The method for producing the PTC composition of the present invention includes (i) a method of thermally melting a crystalline polymer and dispersing the PTC efficiency enhancer and conductive powder of the present invention in this, and (ii) Any of the methods of dissolving molecules and dispersing the PTC efficiency enhancer and conductive powder of the present invention in the molecules can be used.
In the case of the former method, a polymer selected from the above crystalline polymer group is heated to a melting temperature or higher, a PTC efficiency enhancer selected from the above aliphatic amide group, and graphite, carbon black, metal powder Conductive powder selected from the above is added and kneaded until a uniform dispersion is obtained.
In the latter method, the PTC composition is produced in the following order. That is, (1) A solvent is put into a stirring vessel and heated to a temperature of 60 to 160 ° C. (2) Add a polymer selected from the crystalline polymer group described above. (3) As a PTC efficiency enhancer of the present invention, a compound selected from the above aliphatic amide group is added, and stirring is continued until all solid components are dissolved. (4) Add conductive powder selected from graphite, carbon black, metal powder, etc. and stir until a smooth paste is formed. (5) The paste is kneaded until a substantially uniform dispersion of conductive powder is obtained.

  In preparing the PTC composition, various additives may be mixed as necessary in addition to the crystalline polymer, the PTC efficiency enhancer, and the conductive powder. Examples of the additive include a coupling agent; a flame retardant such as an antimony compound, a phosphorus compound, a chlorine compound, and a bromine compound; an antioxidant; and a stabilizer.

<PTC heating element>
As the PTC heating element of the present invention, for example, a substrate formed by forming the polymer PTC composition of the present invention into a sheet, electrodes disposed on the substrate at predetermined intervals, and a synthetic resin coating the substrate A sheet heating element that has a structure in which the chain of the conductive material is partially broken by the thermal expansion of the base body as the temperature rises to increase its electrical resistance. Can do. Furthermore, this planar heating element can be placed on the underfloor material of the building so as to cover the underfloor material and applied as a floor heating structure of the building. However, the polymer PTC composition of the present invention is not limited to these and can be applied to general heating elements.

(Method of enhancing PTC efficiency)
The method for enhancing the PTC efficiency of the present invention is a method of adding a PTC efficiency enhancer comprising a fatty acid amide as a main component to a PTC composition comprising a crystalline polymer and a conductive powder. It is characterized by enhancing the PTC efficiency.
In the method for enhancing PTC efficiency of the present invention, the amount of the PTC efficiency enhancer added is in the range of 0.4 to 50 parts by weight, preferably 0.4 to 100 parts by weight of the crystalline polymer component. The range is preferably from 30 to 30 parts by weight. When the compounding amount of the PTC efficiency enhancer is lower than 0.4 parts by weight, the effect as the PTC enhancer of the present invention cannot be sufficiently exhibited. On the other hand, if it is higher than 50 parts by weight, desired PTC characteristics cannot be expressed.
As a criterion for increasing the PTC efficiency, an equation of PTC efficiency (P) = R _max / R _{20 ° C.} (R _max represents an electric resistance maximum value and R _{20 ° C.} represents an electric resistance value at 20 ° C.) is used. be able to.

   EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example, this invention is not limited to this range.

(Example 1)
The polymer was heated to a melting temperature or higher, and a PTC efficiency enhancer selected from aliphatic amides and a conductive powder selected from graphite, carbon black, and metal powder were added and kneaded until a uniform dispersion was obtained. .
As a polymer, 48 parts by weight of “J-Rex EEA A6200” (ethylene-ethacrylate copolymer resin, manufactured by Nippon Polyethylene Co., Ltd.) and 12 parts by weight of “Fatty Acid Amide T” (manufactured by Kao Corporation) as a PTC efficiency reinforcing agent Using. Further, 40 parts by weight of graphite “JSP” (manufactured by Nippon Graphite Industry Co., Ltd.) was added as a conductive powder.
This was extruded to form a sheet having a thickness of 1 mm, the sheet was cut into a size of 100 mm × 80 mm, and copper paint was applied to form an electrode. The gap between the electrodes was 70 mm, the electrode length was 100 mm, and the electrode width was 10 mm. An aluminum foil was adhered to the electrode with silver paint to form a lead, and the electrical resistance at each temperature was measured under temperature control in an air thermostat. Resistance measurements were taken into a computer via the GPIB interface using Agilent 3490A-Date acquisition switching unit and 34901A-20 channel multiplexer.
The temperature increase / decrease cycle was repeated 10 times between 0 ° C. and 100 ° C. Since the data fluctuated at the beginning of the cycle, data up to the fourth cycle was not used, and data of 5 to 10 cycles are shown in Table 1 as a result. A graph of 5 to 10 cycles is shown in FIG. The electrical resistance of 108Ω or more was not measurable due to the equipment.

(Example 2)
The same procedure as in Example 1 except that 12 parts by weight of “Fatty Acid Amide S” (manufactured by Kao Corporation) was added as a PTC efficiency reinforcing agent. The results for 5 to 10 cycles are shown in Table 1. A graph of 5 to 10 cycles is shown in FIG.

(Example 3)
48 parts by weight of “Lexpearl RB6200” (ethylene-methyl acrylate copolymer resin, manufactured by Nippon Polyethylene Co., Ltd.) is dissolved as a polymer, and 12 parts by weight of “Nutron 2” (Nippon Seika Co., Ltd.) as a PTC efficiency reinforcing agent. (Made by Co., Ltd.) was dissolved. As the conductive powder, 38 parts by weight of graphite “JSP” (manufactured by Nippon Graphite Industries Co., Ltd.) and 2 parts by weight of carbon black “4500” (manufactured by Tokai Carbon Co., Ltd.) were added.
Other conditions were the same as in Example 1. The results for 5 to 10 cycles are shown in Table 1. A graph of 5 to 10 cycles is shown in FIG.

Example 4
48 parts by weight of “Acrylift WH401” (ethylene-methyl methacrylate copolymer resin, MMA 20 wt%, manufactured by Sumitomo Chemical Co., Ltd.) is dissolved as a polymer, and 12 parts by weight of “Fatty Acid Amide 0- N "(manufactured by Kao Corporation) was dissolved. As conductive powder, 40 parts by weight of graphite “JSP” (manufactured by Nippon Graphite Industry Co., Ltd.) was added.
Other conditions were the same as in Example 1. The results for 5 to 10 cycles are shown in Table 1. A graph of 5 to 10 cycles is shown in FIG.

(Example 5)
48 parts by weight of “Acrylift WK402” (ethylene-methyl methacrylate copolymer resin, containing MMA 25 wt%, manufactured by Sumitomo Chemical Co., Ltd.) is dissolved as a polymer, and 12 parts by weight of “fatty acid amide 0- N "(manufactured by Kao Corporation) was dissolved. As conductive powder, 40 parts by weight of graphite “JSP” (manufactured by Nippon Graphite Industry Co., Ltd.) was added.
Other conditions were the same as in Example 1. The results for 5 to 10 cycles are shown in Table 1. Moreover, the graph of 5-10 cycles was shown in FIG.

(Example 6)
48 parts by weight of “Acrylift WK402” (ethylene-methyl methacrylate copolymer resin, MMA containing 25 wt%, manufactured by Sumitomo Chemical Co., Ltd.) is dissolved as a polymer, and 12 parts by weight of “Excel T-95 is used as a PTC efficiency reinforcing agent. (Made by Kao Corporation) was dissolved. As conductive powder, 40 parts by weight of graphite “JSP” (manufactured by Nippon Graphite Industry Co., Ltd.) was added.
Other conditions were the same as in Example 1. The results for 5 to 10 cycles are shown in Table 1. A graph of 5 to 10 cycles is shown in FIG.

(Example 7)
48 parts by weight of “Lexpearl RB6200” (ethylene-methyl acrylate copolymer resin, manufactured by Nippon Polyethylene Co., Ltd.) is dissolved as a polymer, and 12 parts by weight of “Fatty Acid Amide E” (Kao Corporation) is used as a PTC efficiency reinforcing agent. Made) was dissolved. As conductive powder, 40 parts by weight of graphite “JSP” (manufactured by Nippon Graphite Industry Co., Ltd.) was added.
Other conditions were the same as in Example 1. The results for 5 to 10 cycles are shown in Table 1. A graph of 5 to 10 cycles is shown in FIG.

(Example 8)
48 parts by weight of “J-Rex EEA A6200” (ethylene-ethacrylate copolymer resin, manufactured by Nippon Polyethylene Co., Ltd.) as a polymer, and 12 parts by weight of “Fatty Acid Amide S” (manufactured by Kao Corporation) as a PTC efficiency reinforcing agent Using. Further, 40 parts by weight of graphite “JSP” (manufactured by Nippon Graphite Industry Co., Ltd.) was added as a conductive powder.
Other conditions were the same as in Example 1. The results for 5 to 10 cycles are shown in Table 1. A graph of 5 to 10 cycles is shown in FIG.

Example 9
As a polymer, 48 parts by weight of “J-Rex EEA A6200” (ethylene-ethacrylate copolymer resin, manufactured by Nippon Polyethylene Co., Ltd.) and as a PTC efficiency reinforcing agent, 12 parts by weight of “Nutron 2” (manufactured by Nippon Seika Co., Ltd.) ) Was dissolved. As the conductive powder, 38 parts by weight of graphite “JSP” (manufactured by Nippon Graphite Industries Co., Ltd.) and 2 parts by weight of carbon black “4500” (manufactured by Tokai Carbon Co., Ltd.) were added.
Other conditions were the same as in Example 1. The results for 5 to 10 cycles are shown in Table 1. A graph of 5 to 10 cycles is shown in FIG.

(Comparative Example 1)
60 parts by weight of “J-Rex EEA A6200” (ethylene-ethacrylate copolymer resin, manufactured by Nippon Polyethylene Co., Ltd.) is dissolved as a polymer, and 40 parts by weight of graphite “JSP” (Nippon Graphite Industries Co., Ltd.) is used as a conductive powder. And kneaded until a uniform dispersion is obtained.
This was extruded to form a sheet having a thickness of 1 mm, the sheet was cut into a size of 100 mm × 80 mm, and copper paint was applied to form an electrode. The gap between the electrodes was 70 mm, the electrode length was 100 mm, and the electrode width was 10 mm. When aluminum foil was bonded to this electrode with silver paint to form a lead and the electrical resistance at each temperature was measured under temperature control in an air thermostat, the initial resistance was infinite and measurement was impossible. Therefore, a sheet of 55 mm × 90 mm was prepared, silver paint was applied on both sides, and evaluation was made by volume resistance.
The resistance measurement was taken into the computer via the GPIB interface using Agilent 3490A-Date acquisition switching unit and 34901A-20 channel multiplexer as in the above example.
The temperature increase / decrease cycle was repeated 10 times between 0 ° C. and 100 ° C. Since data fluctuated at the beginning of the cycle, data up to the third cycle was not used, and data of 4 to 10 cycles are shown in Table 1 as a result. A graph of 5 to 10 cycles is shown in FIG. In FIG. 10, as described above, measurement was impossible under the same conditions as in the example, so the vertical axis of the graph was the volume resistance.

(result)
The measurement results are shown in Table 1.
From the results of Examples 1 to 9 and Comparative Example 1, the PTC efficiency enhancer of the present invention was evaluated. The evaluation was performed by calculating PTC efficiency (P) = R _max / R _{20 ° C.} (R _max represents an electric resistance maximum value, and R _{20 ° C.} represents an electric resistance value at 20 ° C.).
As a result, the enhancers of Examples 1 to 3, 8, and 9 achieved the above-described object of the present invention, and favorable results were obtained as PTC efficiency enhancers. That is, the enhancers of Examples 1 to 3, 8, and 9 had a low initial resistance value and followed substantially the same path in the lifting cycle. Further, the rise of the PTC characteristic is abrupt and shows a large resistance change, the PTC characteristic after the repeated switching operation is stable, and can be suitably added to the PTC composition as an additive for improving the PTC efficiency.
On the other hand, the additive of Examples 4-7 did not become a suitable result so that the objective of the above-mentioned this invention was achieved. Examples 4-6 were found to follow different paths in the lift cycle. Further, Example 7 followed substantially the same path in the lifting cycle, but the initial resistance value was relatively high, and the rise of the resistance value was slightly gentle.

  According to the present invention, the PTC efficiency of the polymer PTC composition can be remarkably increased by adding a PTC efficiency enhancer mainly composed of fatty acid amide or the like to the PTC composition. That is, it was possible to obtain a PTC composition and a PTC heating element having a rapid rise in PTC characteristics and a large resistance change, a low resistance at normal temperature, and a stable PTC characteristic after repeated switching operations.

It is a figure corresponding to Example 1 of the present invention. It is a figure corresponding to Example 2 of the present invention. It is a figure corresponding to Example 3 of the present invention. It is a figure corresponding to Example 4 of the present invention. It is a figure corresponding to Example 5 of the present invention. It is a figure corresponding to Example 6 of the present invention. It is a figure corresponding to Example 7 of the present invention. It is a figure corresponding to Example 8 of the present invention. It is a figure corresponding to Example 9 of the present invention. It is a figure corresponding to the comparative example 1 of this invention.

Claims (5)

  A polymer PTC composition having a crystalline polymer and a conductive powder, a PTC efficiency enhancer that is added to the polymer PTC composition to increase PTC efficiency, and comprises a fatty acid amide as a main component. A characteristic PTC efficiency enhancer.   The fatty acid amide is stearic acid amide, oleic acid amide, lauric acid amide, palmitic acid amide, erucic acid amide, behenic acid amide, ethylene bisstearic acid amide, ethylene bis lauric acid amide, N-oleyl palmitamide, N- The PTC efficiency enhancer according to claim 1, wherein the PTC efficiency enhancer is one or more of stearyl erucamides.   A polymer PTC composition having a crystalline polymer and a conductive powder, comprising the PTC efficiency enhancer according to claim 1 or 2.   A PTC heating element comprising the polymer PTC composition according to claim 3.   A method for enhancing the PTC efficiency of a polymer PTC composition by adding a fatty acid amide in a polymer PTC composition having a crystalline polymer and a conductive powder.

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