CN115595008A

CN115595008A - Conductive micro powder for polymer-based PTC (Positive temperature coefficient) material, preparation method of conductive micro powder and PTC self-temperature-control coating

Info

Publication number: CN115595008A
Application number: CN202211153557.XA
Authority: CN
Inventors: 王明科; 张忠厚; 韩琳; 程伟伟; 王亚男; 任可可; 林宝德; 陈荣源; 张赛; 温阳
Original assignee: Zhengzhou Light Industry Technology Research Institute Co ltd; Henan Puliteke New Material Co ltd
Current assignee: Zhengzhou Light Industry Technology Research Institute Co ltd; Henan Puliteke New Material Co ltd
Priority date: 2022-09-21
Filing date: 2022-09-21
Publication date: 2023-01-13

Abstract

The invention relates to conductive micro powder for a polymer-based PTC material, a preparation method thereof and a PTC self-temperature-control coating, belonging to the technical field of polymer-based PTC materials. The conductive micro powder comprises a solid filler for a polymer-based PTC material and a crystalline organic substance layer coated on the surface of the solid filler for the polymer-based PTC material; the solid filler for the polymer-based PTC material comprises a conductive carbon material; the main component of the crystalline organic matter layer is a crystalline organic matter, and the mass ratio of the conductive carbon material to the crystalline organic matter is 10-120; the grain diameter of the conductive micro powder is less than or equal to 80 mu m. The conductive micro powder can obviously inhibit the NTC phenomenon of the polymer-based PTC material and improve the safety of the polymer-based PTC material.

Description

Conductive micro powder for polymer-based PTC (Positive temperature coefficient) material, preparation method of conductive micro powder and PTC self-temperature-control coating

Technical Field

The invention relates to conductive micro powder for a polymer-based PTC material, a preparation method thereof and a PTC self-temperature-control coating, belonging to the technical field of polymer-based PTC materials.

Background

PTC (positive temperature coefficient) materials, i.e. positive temperature coefficient materials, have a non-linear change in resistance with the increase of temperature, and self-adjust along a specific transformation curve, and the resistivity can jump by several orders of magnitude within a specific temperature range, thus completing the transformation from conductive materials or semi-conductive materials to insulating materials. The special temperature response capability endows the switch with a response characteristic, and the switch has wide application in the fields of smart home, electric heating sensing, heat preservation buildings, new energy lithium batteries and the like. PTC materials are divided into two major classes, ceramic-based PTC materials and polymer-based PTC materials. The PTC material based on ceramic matrix mainly induces the increase or decrease of the resistivity by depending on the change of the material grain boundary barrier potential barrier under different temperatures, the adjustment and control of the resistivity and the PTC characteristic are completed by adding donor elements and acceptor elements with different types and proportions under normal conditions, the technology of the PTC material based on ceramic matrix is already about to be perfect at present, and a series of temperature control products can be widely seen in the market.

Compared with ceramic-based PTC materials, polymer PTC materials have the advantages of easily available raw materials, low price, light weight, easy processing and preparation, low room temperature resistivity and the like, and also have many excellent properties of high polymer materials, so the polymer PTC materials are increasingly attracted by people. The self-temperature control characteristic of the polymer-based PTC material is from the damage of a conductive network caused by the thermal expansion of a resin matrix, and the service temperature of the polymer-based PTC material is influenced by the glass transition temperature and the melting point of the polymer matrix. The common polymer-based PTC material on the market is a composite material formed by filling a certain amount of carbon conductive filler in a polymer, mainly medium-low temperature electric heating series products are used, the temperature control temperature is generally less than or equal to 80 ℃, most high temperature is ceramic-based PTC material, and the common polymer-based PTC material cannot be made into coating and is limited in application in many occasions. In addition, from the current industrialized products, most of the PTC self-temperature control components often exist in a three-dimensional block shape and are hard, so that the application of the PTC self-temperature control components in a complex or narrow area is greatly limited. The PTC coating has the characteristic of flexible use, and can get rid of the limitation of the use environment on the PTC material. For example, chinese patent application No. CN108912990A discloses an aqueous PTC nanocarbon electrothermal coating, which is composed of a conductive carbon material, polymer micropowder, an auxiliary agent, aqueous binder resin and water, and its basic composition and weight percentage are: 1-20% of conductive carbon material, 2-15% of polymer micro powder, 1-10% of assistant, 10-30% of water-based bonding resin and the balance of water; wherein the polymer micropowder is crystalline thermoplastic polymer powder with particle size of 200 nm-5 μm, or any one or combination of polyethylene, polypropylene, nylon, polyethylene terephthalate, polybutylene terephthalate and polyformaldehyde. The water-based PTC nano carbon electric heating coating utilizes the crystallization-softening transformation in the thermal cycle of the crystalline thermoplastic polymer to drive the change of the nano carbon conductive network, thereby changing the resistance inside the coating, obtaining the positive temperature resistance (PTC) effect, realizing the regulation and control of the power of the electric heating coating and obtaining the safe and efficient electric heating coating. However, when the conductive carbon material and the polymer micro powder are adopted for preparing the coating, the coating is independently added into the system, the PTC strength can only reach 5 at most, and thermal runaway can easily occur when the voltage is unstable or the local temperature is increased, which is unfavorable for the use safety of the coating; in addition, crystallization-softening transition is taken as a main factor for regulating and controlling a conductive network in the PTC electric heating coating, when the temperature approaches to a softening point or a melting point of a polymer, mutually communicated polymer molecules are subjected to thermal deformation, the molecular chain moves violently, the shrinkage recovery performance and the recovery performance of spatial arrangement of the mutually communicated polymers are influenced after the temperature is reduced, the room temperature resistance recovery performance under long-term use is unfavorable, the problems of room temperature resistance increase and the like easily occur in the later period, and the service life of the PTC electric heating coating is influenced.

Disclosure of Invention

The invention aims to provide conductive micro powder for a polymer-based PTC material, which can solve the problems that a PTC electric heating coating is easy to generate thermal runaway and the room temperature resistance is easy to increase after long-term use.

The invention also provides a preparation method of the conductive micro powder for the polymer-based PTC material.

The invention also provides a PTC self-temperature-control coating which has excellent high-temperature stability.

In order to achieve the above object, the conductive fine powder for a polymer-based PTC material of the present invention adopts the technical scheme that:

a conductive micropowder used for polymer-based PTC material, comprising solid filler for polymer-based PTC material and crystalline organic substance layer coated on the surface of the solid filler for polymer-based PTC material; the solid filler for the polymer-based PTC material comprises a conductive carbon material; the main component of the crystalline organic matter layer is crystalline organic matter, and the mass ratio of the conductive carbon material to the crystalline organic matter is 10-120; the particle size of the conductive micro powder is less than or equal to 80 mu m.

According to the conductive micro powder for the polymer-based PTC material, the surface of the conductive carbon material is coated with the crystalline organic matter, so that on one hand, the conductive carbon material can be in a state of clear particle size, the agglomeration of the conductive carbon material is well limited, and meanwhile, the crystalline organic matter on the surface of the conductive carbon material has excellent compatibility with matrix resin, and the uniform dispersion of the conductive carbon material in the coating can be promoted; on the other hand, the conductive carbon material can be distributed in the resin system in an isolated island form due to the blocking effect of the crystalline organic substance. Under the room temperature state, the carbon materials of different types form a rich and compact conductive network with each other, and the PTC material is endowed with excellent room temperature resistivity and electrothermal property.

In addition, due to the special structural relationship between the conductive carbon material and the crystalline organic matter in the conductive micro powder, the NTC phenomenon of the polymer-based PTC material can be obviously inhibited, and the safety of the polymer-based PTC material is improved, because the crystalline organic matter exists in an isolated island form due to a coating structure, the crystalline organic matter is independently distributed in a resin matrix in most cases and only a small amount of the crystalline organic matter is bonded; therefore, even if the temperature is locally increased, the molten crystalline organic substance can be firmly fixed in a narrow space by the matrix resin, and the rearrangement of the conductive carbon material to form a new conductive network is inhibited, so that the NTC phenomenon of the polymer-based PTC material is effectively inhibited, and the electrical recovery of the polymer-based PTC material is improved. Meanwhile, because the crystalline organic matter is coated on the surface of the conductive carbon material, the carbon materials adjacent to each other can be forced to separate by slight expansion, so that the damage of the conductive network is caused, and higher PTC strength is provided for the conductive network.

Further, the melting point of the crystalline organic matter is T, and T is more than or equal to 40 ℃ and less than 80 ℃ or T is more than or equal to 80 ℃; t is more than or equal to 40 ℃ and less than 80 ℃, and the crystalline organic matter is a crystalline polymer and/or a non-polymer crystalline organic matter; when T is more than or equal to 80 ℃, the crystalline organic matter is a crystalline polymer.

Further, T is more than or equal to 40 ℃ and less than 80 ℃, the crystalline polymer is one or any combination of polyethylene glycol (PEG), ethylene-vinyl acetate copolymer (EVA), oxidized polyethylene wax (OPE) and Polycaprolactone (PCL), and the non-polymer crystalline organic matter is one or any combination of palmitic acid, lauric acid and 12-hydroxystearic acid; or T is more than or equal to 80 ℃ and less than or equal to 120 ℃, and the crystalline polymer is one or any combination of Polyethylene (PE), polyethylene wax (PEW), polypropylene (PP), ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), ethylene-acrylic acid copolymer (EAA), polyethylene oxide (PEO), polyvinyl chloride (PVC) and Chlorinated Polyethylene (CPE).

Further, the mass ratio of the conductive carbon material to the crystalline organic substance is 42 to 57, for example, 45 to 56.7 or 42.8 to 52.5.

Further, the conductive carbon material is a graphene two-dimensional carbon material, superconducting carbon black and carbon fiber; the mass ratio of the graphene-based two-dimensional carbon material, the superconducting carbon black, the carbon fibers and the crystalline organic material is (5-30). The sheet diameter of the graphene two-dimensional carbon material is 300nm-15 mu m; the grain size of the superconducting carbon black is 35-300nm; the monofilament diameter of the carbon fiber is 1-10 μm, and the length-diameter ratio is 2-15.

Furthermore, the grain diameter of the conductive micro powder is less than or equal to 75 mu m. The conductive fine powder has an average particle diameter of 10 to 30 μm, for example, 21 to 28 μm.

Further, the graphene two-dimensional carbon material is one or any combination of single-layer graphene, multi-layer graphene and graphene oxide; the superconducting carbon black is acetylene carbon black and/or ketjen black.

Further, the solid filler for the polymer-based PTC material further comprises an inorganic heat conductive filler; the mass ratio of the inorganic heat-conducting filler to the crystalline organic substance is 5 to 30, preferably 13 to 20, for example 13.3 to 20.

The preparation method of the conductive micro powder for the polymer-based PTC material adopts the technical scheme that:

a preparation method of conductive micro powder for a polymer-based PTC material comprises the following steps: drying the mixed slurry into solid, and then crushing into micro powder; the mixed slurry is obtained by dispersing solid fillers for the polymer-based PTC material in crystalline organic emulsion; the solid filler for the polymer-based PTC material comprises a conductive carbon material; the mass ratio of the conductive carbon material to the crystalline organic matter in the crystalline organic matter emulsion is 10-120; the grain diameter of the conductive micro powder is less than or equal to 80 mu m.

The preparation method of the conductive micro powder for the polymer-based PTC material can improve the dispersion uniformity of the solid filler for the polymer-based PTC material in the prepared conductive micro powder.

Furthermore, the particle size of the conductive micro powder is less than or equal to 75 microns. The conductive fine powder has an average particle diameter of 10 to 30 μm, for example, 21 to 28 μm.

Further, the mass ratio of the conductive carbon material to the crystalline organic substance in the crystalline organic substance emulsion is 27 to 34.

Furthermore, the melting point of the crystalline organic matter is T, and T is more than or equal to 40 ℃ and less than 80 ℃ or T is more than or equal to 80 ℃; t is more than or equal to 40 ℃ and less than 80 ℃, and the crystalline organic matter is crystalline polymer and/or non-polymeric crystalline organic matter; when T is more than or equal to 80 ℃, the crystalline organic matter is a crystalline polymer.

Further, T is more than or equal to 40 ℃ and less than 80 ℃, the crystalline polymer is one or any combination of polyethylene glycol, ethylene-vinyl acetate copolymer, oxidized polyethylene wax and polycaprolactone, and the non-polymer crystalline organic matter is one or any combination of palmitic acid, lauric acid and 12-hydroxystearic acid; or T is more than or equal to 80 ℃ and less than or equal to 120 ℃, and the crystalline polymer is one or any combination of polyethylene, polyethylene wax, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-acrylic acid copolymer, polyoxyethylene, polyvinyl chloride and chlorinated polyethylene. For example, the ethylene-vinyl acetate copolymer has a VA content of 28% or 40%. For example, the crystalline polymer is polyethylene glycol with melting point of 58-63 deg.C, ethylene-vinyl acetate copolymer with melting point of 70 deg.C or stearic acid with melting point of 60-65 deg.C, or the crystalline polymer is polyethylene wax with melting point of 100-105 deg.C, polyethylene oxide with melting point of 85-90 deg.C or ethylene-vinyl acetate copolymer with melting point of 95 deg.C.

Further, the conductive carbon material comprises the following components in parts by weight: 5-30 parts of graphene two-dimensional carbon material, 5-40 parts of superconducting carbon black and 0-50 parts of carbon fiber, namely: the conductive carbon material is composed of a graphene two-dimensional carbon material, superconducting carbon black and carbon fibers, and the mass ratio of the graphene two-dimensional carbon material to the superconducting carbon black to the carbon fibers is 5-30. Further, the mass ratio of the graphene two-dimensional carbon material, the superconducting carbon black and the carbon fiber is 16 to 30. The mass ratio of the graphene-based two-dimensional carbon material to the crystalline organic material is 5 to 30, preferably 16 to 30, for example, 16.6 to 30.

Further, the sheet diameter of the graphene-based two-dimensional carbon material is 300nm to 15 μm, preferably 0.5 to 8 μm, for example, 0.5 to 3 μm, 0.8 to 5 μm, or 5 to 8 μm; the particle size of the superconducting carbon black is 30-300nm, preferably 30-240 nm, such as 30-45nm, 45-70 nm or 200-240nm; the carbon fibers have a filament diameter of 1 to 10 μm, for example 2.6 μm, 5 μm or 6.5 μm, and an aspect ratio of 2 to 15.

Further, the superconducting carbon black is acetylene carbon black and/or ketjen black; the graphene two-dimensional carbon material is one or any combination of single-layer graphene, multi-layer graphene and graphene oxide.

Further, the crystalline organic substance emulsion is formed by dispersing crystalline organic substances in water; the preparation method of the crystalline organic substance emulsion comprises the following steps: heating the crystalline organic matter, the emulsifying agent and the dispersing agent to a temperature higher than the melting point of the crystalline organic matter, melting and uniformly mixing, and then adding water to carry out dispersion and emulsification under set pressure and set temperature to obtain the composite material. The boiling point of water at the set pressure is not lower than the melting point of the crystalline organic substance, and the set temperature is not higher than the boiling point of water at the set pressure.

Further, the emulsifier is an anionic emulsifier and/or a nonionic emulsifier; the anionic emulsifier is one or any combination of alkyl sulfate, alkyl sulfonate and alkylbenzene sulfonate; the alkyl sulfate is sodium dodecyl sulfate; the alkyl sulfonate is sodium dodecyl sulfonate; the alkylbenzene sulfonate is sodium dodecyl benzene sulfonate; the non-ionic emulsifier is one or any combination of alkylphenol polyoxyethylene ether emulsifier, sorbitan fatty acid ester emulsifier and polyoxyethylene sorbitan fatty acid ester emulsifier; the alkylphenol polyoxyethylene ether emulsifier is one or any combination of OP-6, OP-7, OP-8 and OP-9; the sorbitan fatty acid ester emulsifier is one or any combination of Span 40, span60 and Span 80; the polyoxyethylene sorbitan fatty acid ester emulsifier is one or any combination of Tween-20, tween-40 and Tween-60.

Further, the dispersing agent is one or any combination of a fatty acid dispersing agent, a fatty amide dispersing agent and a glyceride dispersing agent; the fatty acid dispersant is one or any combination of myristic acid, palmitic acid and stearic acid; the aliphatic amide dispersant is one or any combination of stearic acid amide, erucic acid amide, oleic acid diethanol amide and vinyl distearamide; the glyceride dispersant is one or any combination of caprylic capric glyceride, diglyceride and stearic acid monoglyceride.

Further, the solid filler for the polymer-based PTC material further comprises an inorganic heat-conducting filler, wherein the mass ratio of the inorganic heat-conducting filler to the crystalline organic substance in the crystalline organic substance emulsion is 5-30; the particle size of the inorganic heat-conducting filler is 50nm to 5 μm, preferably 1.3 to 5 μm, for example, 1.3 to 1.5 μm or 3 to 5 μm.

It is understood that the inorganic thermally conductive filler is a semiconductor filler and/or a non-electrically conductive filler. The inorganic heat conductive filler has a regular crystal structure. Further, the inorganic heat conducting filler is selected from one or any combination of silicon carbide, silicon dioxide, boron nitride and aluminum nitride.

The PTC self-temperature-control coating adopts the technical scheme that:

a PTC self-temperature-control coating comprises a resin emulsion, conductive micro powder and an additive, wherein the conductive micro powder and the additive are dispersed in the resin emulsion; the conductive micro powder is the conductive micro powder for the polymer-based PTC material or the conductive micro powder for the polymer-based PTC material prepared by the preparation method of the conductive micro powder for the polymer-based PTC material.

Compared with the common low-temperature PTC self-temperature control coating, the PTC self-temperature control coating belongs to a high-temperature PTC self-temperature control coating, and the electrothermal film formed after coating has good electrical resilience, heating stability, low room temperature resistance, excellent high and low temperature stability, no thermal aging even if the coating is used for a long time, good self-temperature control effect, high use safety and wide application prospect. The PTC self-temperature-control coating disclosed by the invention is simple in preparation process, can be prepared by only uniformly mixing all the raw materials, is flexible in construction process, is easy to print into various shapes, and has good customizable attributes.

Particularly, the melting point of the crystalline polymer in the conductive micro powder is 80-120 ℃, and when the crystalline polymer is one or any combination of polyethylene, polyethylene wax, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-acrylic acid copolymer, polyethylene oxide, polyvinyl chloride and chlorinated polyethylene, the PTC self-temperature control coating has good self-temperature control characteristic at 75-110 ℃, and fills the gap in the temperature range of the commercial PTC material.

Further, the mass ratio of the solid matter in the resin emulsion to the crystalline organic matter in the conductive fine powder is 30 to 60, preferably 45 to 60.

It can be understood that the resin emulsion of the invention is water-based resin emulsion, and when the resin in the resin emulsion is thermoplastic polymer, the melting point or softening point of the polymer formed by the resin after the PTC self-temperature-control coating is cured is higher than the melting point of the crystalline organic matter in the conductive micro powder; when the resin in the resin emulsion is a thermosetting polymer, the thermal deformation temperature of the polymer formed after the PTC self-temperature-control coating is cured is not lower than the melting point of the crystalline organic matter in the conductive micro powder. Further, the resin emulsion is one or any combination of polyurethane emulsion, acrylic emulsion, acrylate emulsion, organic silicon emulsion and epoxy resin emulsion; the solid content of the resin emulsion is 30-60%. For example, the acrylate emulsion is any one or any combination of silicone-acrylic emulsion, styrene-acrylic emulsion and pure acrylic emulsion. Further, the aqueous resin emulsion may be a one-component aqueous resin emulsion or a two-component aqueous resin emulsion. It is understood that the one-component aqueous resin emulsion is a self-crosslinking aqueous resin emulsion. For example, the epoxy resin emulsion and the polyurethane emulsion may be two-component emulsions or may be one-component emulsions.

Further, the additives include a defoaming agent and a leveling agent; the mass ratio of the defoaming agent to the leveling agent to the resin emulsion is 3-50.

Further, the defoaming agent is an organic silicon type defoaming agent and/or a polyether modified organic silicon type defoaming agent; the leveling agent is one or any combination of an acrylic leveling agent, an acrylate leveling agent and an organic silicon leveling agent; the main component of the acrylic leveling agent is acrylic acid homopolymer and/or acrylic acid copolymer, and the molecular weight of the acrylic acid homopolymer and the molecular weight of the acrylic acid copolymer are both 6000 to 20000; the main component of the organic silicon leveling agent is polydimethylsiloxane and/or polyether modified polydimethylsiloxane; the main component of the organic silicon type defoaming agent is polydimethylsiloxane, and the polyether modified organic silicon type defoaming agent is one or any combination of an amino polyether organic silicon defoaming agent, an alkoxy polyether organic silicon defoaming agent and a hydroxyl polyether organic silicon defoaming agent.

Further, the defoaming agent is one or any combination of a BYK-024 organic silicon defoaming agent, a BYK-067A organic silicon defoaming agent and a BYK-028 organic silicon defoaming agent, and the leveling agent is one or any combination of a BYK-349 organic silicon leveling agent, a BYK-380 acrylic leveling agent and a BYK-333 polyether modified organic silicon leveling agent.

Drawings

FIG. 1 is a graph showing the results of performance tests of an electrothermal film prepared in Experimental example 1 by using PTC self-temperature-controlling coatings of examples 13 to 15 and comparative examples 1 to 2;

FIG. 2 is a graph showing the results of performance tests of the electric heating films prepared in Experimental example 2 by using the PTC self-temperature-controlling paints of examples 16 to 18 and comparative examples 2 to 3.

Detailed Description

The technical solution of the present invention will be further described with reference to the following embodiments.

Example 1

The conductive micro powder for the polymer-based PTC material comprises a solid filler for the polymer-based PTC material and a crystalline organic substance layer coated on the surface of the solid filler for the polymer-based PTC material; the solid filler for the polymer-based PTC material is graphite two-dimensional carbon material, superconducting carbon black, carbon fiber and aluminum nitride, the mass ratio of the graphene two-dimensional carbon material to the superconducting carbon black to the carbon fiber to the aluminum nitride is 150; the monofilament diameter of the carbon fiber is 6.5 μm, and the length-diameter ratio is 2-15; the grain diameter of the aluminum nitride is 3-5 μm; the main component of the crystalline organic substance layer is polyoxyethylene, and the melting point is 85-90 ℃; the mass ratio of the graphite two-dimensional carbon material to the polyethylene oxide is 150; the particle size of the conductive micro powder is less than or equal to 75 μm, and the average particle size is 26 μm.

The conductive fine powder for a polymer-based PTC material of this example can be prepared by the method of example 7.

Example 2

The conductive micro powder for the polymer-based PTC material comprises a solid filler for the polymer-based PTC material and a crystalline organic substance layer coated on the surface of the solid filler for the polymer-based PTC material; the solid filler for the polymer-based PTC material is graphite two-dimensional carbon material, superconducting carbon black, carbon fiber and silicon carbide, the mass ratio of the graphite two-dimensional carbon material to the superconducting carbon black to the carbon fiber to the aluminum nitride is 100; the monofilament diameter of the carbon fiber is 5 mu m, and the length-diameter ratio is 2-15; the grain diameter of the silicon carbide is 1.3-1.5 mu m; the main component of the crystalline organic layer is polyethylene wax, and the melting point is 100-105 ℃; the mass ratio of the graphite two-dimensional carbon material to the polyethylene wax is 100; the particle size of the conductive micro powder is less than or equal to 75 mu m, and the average particle size is 25 mu m.

The conductive fine powder for a polymer-based PTC material of this example can be prepared by the preparation method of example 8.

Example 3

The conductive micro powder for the polymer-based PTC material comprises a solid filler for the polymer-based PTC material and a crystalline organic substance layer coated on the surface of the solid filler for the polymer-based PTC material; the solid filler for the polymer-based PTC material is graphite two-dimensional carbon material, superconducting carbon black, carbon fiber and silicon carbide, the mass ratio of the graphene two-dimensional carbon material to the superconducting carbon black to the carbon fiber to the aluminum nitride is 180; the monofilament diameter of the carbon fiber is 2.6 mu m, and the length-diameter ratio is 2-15; the grain diameter of the aluminum nitride is 3-5 μm; the main component of the crystalline organic layer is ethylene-vinyl acetate copolymer (VA content is 28%), and the melting point is 95 ℃; the mass ratio of the graphite two-dimensional carbon material to the ethylene-vinyl acetate copolymer is 180; the particle size of the conductive micro powder is less than or equal to 75 μm, and the average particle size is 21 μm.

The conductive fine powder for a polymer-based PTC material of this example can be prepared by the preparation method of example 9.

Example 4

The conductive micro powder for the polymer-based PTC material comprises a solid filler for the polymer-based PTC material and a crystalline organic substance layer coated on the surface of the solid filler for the polymer-based PTC material; the solid filler for the polymer-based PTC material is a graphene two-dimensional carbon material, superconducting carbon black, carbon fiber and silicon carbide, wherein the mass ratio of the graphene two-dimensional carbon material to the superconducting carbon black to the carbon fiber to the silicon carbide is 150; the graphene two-dimensional carbon material is multilayer graphene with the sheet diameter of 5-8 mu m; the superconducting carbon black is acetylene carbon black with the particle size of 30-45nm; the monofilament diameter of the carbon fiber is 6.5 μm, and the length-diameter ratio is 2-15; the grain diameter of the silicon carbide is 1.3-1.5 μm; the crystalline organic layer consists of polyethylene glycol 20000, OP-6, span80 and caprylic/capric glyceride, and the melting point of the polyethylene glycol is 58-63 ℃; the mass ratio of the polyethylene glycol to the graphene-based two-dimensional carbon material is 300. The conductive fine powder of this example had a particle size of 75 μm or less and an average particle size of 28 μm.

The conductive fine powder for a polymer-based PTC material of this example can be prepared by the preparation method of example 10.

Example 5

The conductive micro powder for the polymer-based PTC material comprises a solid filler for the polymer-based PTC material and a crystalline organic substance layer coated on the surface of the solid filler for the polymer-based PTC material; the solid filler for the polymer-based PTC material is a graphene two-dimensional carbon material, superconducting carbon black and carbon fiber, wherein the mass ratio of the graphene two-dimensional carbon material to the superconducting carbon black to the carbon fiber is (130); the graphene two-dimensional carbon material is multilayer graphene oxide, the sheet diameter is 0.8-5 mu m, the superconducting carbon black is Keqin black, and the particle diameter is 35-70nm; the monofilament diameter of the carbon fiber is 5 mu m, and the length-diameter ratio is 2-15; the grain diameter of the silicon carbide is 1.3-1.5 μm; the crystalline organic layer consists of ethylene-vinyl acetate copolymer (VA content 40%), sodium dodecyl sulfate, OP-10 and oleic acid amine, and the melting point of the ethylene-vinyl acetate copolymer is 70 ℃; the mass ratio of the ethylene-vinyl acetate copolymer to the graphene-based two-dimensional carbon material is 300. The conductive fine powder of this example had a particle size of 75 μm or less and an average particle size of 21 μm.

The conductive fine powder for a polymer-based PTC material of this example can be prepared by the preparation method of example 11.

Example 6

The conductive micro powder for the polymer-based PTC material comprises a solid filler for the polymer-based PTC material and a crystalline organic substance layer coated on the surface of the solid filler for the polymer-based PTC material; the solid filler for the polymer-based PTC material is a graphene two-dimensional carbon material, superconducting carbon black, carbon fiber and aluminum nitride, and the mass ratio of the graphene two-dimensional carbon material to the superconducting carbon black to the carbon fiber to the silicon carbide is 120; the graphene two-dimensional carbon material is multilayer graphene with the sheet diameter of 0.5-3 mu m, and the superconducting carbon black is acetylene carbon black with the particle diameter of 30-45nm; the monofilament diameter of the carbon fiber is 2.6 mu m, and the length-diameter ratio is 2-15; the grain diameter of the aluminum nitride is 3-5 μm; the crystalline organic layer consists of stearic acid, polyvinyl alcohol and stearic acid monoglyceride, and the melting point of the stearic acid is 60-65 ℃; the mass ratio of the stearic acid to the graphene-based two-dimensional carbon material is 350. The conductive fine powder of this example had a particle size of 75 μm or less and an average particle size of 27 μm.

The conductive fine powder for a polymer-based PTC material of this example can be prepared by the preparation method of example 12.

Example 7

The preparation method of the conductive micro powder for the polymer-based PTC material of the embodiment comprises the following steps:

1) Weighing 300g of polyoxyethylene, 54g of polyvinyl alcohol and 30g of glyceryl monostearate, placing the materials in a reaction kettle, heating to 105 ℃ to completely melt the polyoxyethylene, and uniformly stirring; the melting point of the adopted polyoxyethylene is 85-90 ℃;

then, slowly adding 500mL of deionized water at 100 ℃ into a reaction kettle with the temperature maintained at 105 ℃, pressurizing the reaction kettle for 3-6MPa, and then dispersing at the temperature of 105 ℃ at a high speed of 600r/min for 0.5h to completely emulsify polyoxyethylene to obtain crystalline polymer emulsion;

2) Continuously maintaining the temperature of the reaction kettle at 105 ℃, adding 150g of graphene two-dimensional carbon material, 100g of superconducting carbon black, 30g of carbon fiber and 100g of aluminum nitride into the reaction kettle, and then continuously dispersing at 105 ℃ for 1 hour to uniformly mix to obtain mixed slurry; the graphene two-dimensional carbon material is multilayer graphene with the sheet diameter of 5-8 mu m; the superconducting carbon black is ketjen black with the particle size of 35-70nm; the monofilament diameter of the carbon fiber is 6.5 μm, and the length-diameter ratio is 2-15; the grain diameter of the aluminum nitride is 3-5 μm;

slowly cooling the mixed slurry to room temperature, and performing vacuum freeze-drying to obtain a freeze-dried substance; and (3) freeze-grinding the freeze-dried substance, and sieving the ground substance for 4 times by using a 200-mesh sieve after grinding to obtain the conductive micro powder for the polymer-based PTC material, wherein the particle size of the conductive micro powder is less than or equal to 75 microns, and the average particle size of the conductive micro powder is 26 microns.

Example 8

The preparation method of the conductive micro powder for the polymer-based PTC material comprises the following steps:

1) Weighing 300g of polyethylene wax, 50g of OP-6, 4g of Span80 and 30g of vinyl bis stearamide, placing the polyethylene wax, the OP-6, the Span80 and the vinyl bis stearamide into a reaction kettle, heating to 115 ℃ to completely melt the polyethylene wax, and uniformly stirring; the melting point of the adopted polyethylene wax is 100-105 ℃;

then, slowly adding 500mL of deionized water at 100 ℃ into a reaction kettle at 115 ℃, pressurizing the reaction kettle to 3-6MPa, and then dispersing at the temperature of 115 ℃ at a high speed of 750r/min for 0.5h to completely emulsify the polyethylene wax to obtain a crystalline polymer emulsion;

2) Continuously maintaining the temperature of the reaction kettle at 115 ℃, adding 100g of graphene two-dimensional carbon material, 120g of superconducting carbon black, 50g of carbon fiber and 80g of silicon carbide into the reaction kettle, and then continuously dispersing for 1 hour at 115 ℃ and uniformly mixing to obtain mixed slurry; the adopted graphene two-dimensional carbon material is multilayer graphene oxide, and the sheet diameter is 0.8-5 mu m; the superconducting carbon black is acetylene carbon black with the particle size of 30-45nm; the monofilament diameter of the carbon fiber is 5 mu m, and the length-diameter ratio is 2-15; the grain diameter of the silicon carbide is 1.3-1.5 mu m;

slowly cooling the mixed slurry to room temperature, and performing vacuum freeze-drying to obtain a freeze-dried substance; and (3) freeze-drying the substance, and sieving the substance for 4 times by using a 200-mesh sieve after the grinding is finished to obtain the conductive micro powder for the polymer-based PTC material, wherein the average particle size is 25 mu m.

Example 9

The preparation method of the conductive micro powder for the polymer PCT material comprises the following steps:

1) Weighing 300g of ethylene-vinyl acetate copolymer (with the VA content of 28%), 40g of sodium dodecyl sulfate, 20g of OP-10 and 30g of stearic acid amide, placing the materials in a reaction kettle, heating to 100 ℃ to completely melt the ethylene-vinyl acetate copolymer, and uniformly stirring; the melting point of the adopted ethylene-vinyl acetate copolymer is 95 ℃;

then, slowly adding 500mL of deionized water at 100 ℃ into the reaction kettle, pressurizing the reaction kettle to 3-6MPa, and then dispersing at 100 ℃ at a high speed of 700r/min for 0.5h to completely emulsify the ethylene-vinyl acetate copolymer to obtain a crystalline polymer emulsion;

2) Continuously maintaining the temperature of the reaction kettle at 100 ℃, adding 180g of graphene, 80g of superconducting carbon black, 80g of carbon fiber and 120g of aluminum nitride into the reaction kettle, and then continuously dispersing for 1 hour at 100 ℃ and uniformly mixing to obtain mixed slurry; the adopted graphene is multilayer graphene, and the sheet diameter is 0.5-3 mu m; the superconducting carbon black is acetylene carbon black with the particle size of 200-240nm; the monofilament diameter of the carbon fiber is 2.6 μm, and the length-diameter ratio is 2-15; the grain diameter of the aluminum nitride is 3-5 μm;

slowly cooling the mixed slurry to room temperature, and performing vacuum freeze-drying to obtain a freeze-dried substance; and (3) freeze-drying the substance, and sieving the substance for 4 times by using a 200-mesh sieve after the grinding is finished to obtain the conductive micro powder for the polymer-based PTC material, wherein the average particle size is 21 mu m.

Example 10

1) Weighing 300g of polyethylene glycol, 50g of OP-6, 4g of Span80 and 30g of caprylic capric glyceride, placing the materials in a reaction kettle, heating to 85 ℃ to completely melt the polyethylene glycol, and uniformly stirring; the melting point of the polyethylene glycol is 58-63 ℃;

then, slowly adding 500mL of deionized water at 85 ℃ into a reaction kettle with the temperature maintained at 85 ℃, and then dispersing at 85 ℃ at a high speed of 700r/min for 0.5h to completely emulsify the polyethylene glycol to obtain a crystalline polymer emulsion;

2) Continuously maintaining the temperature of the reaction kettle at 85 ℃, adding 150g of graphene two-dimensional carbon material, 80g of superconducting carbon black, 50g of carbon fiber and 110g of silicon carbide into the reaction kettle, and then continuously dispersing at 85 ℃ for 1 hour to uniformly mix to obtain mixed slurry; the adopted graphene two-dimensional carbon material is multilayer graphene with the sheet diameter of 5-8 mu m, and the superconducting carbon black is acetylene carbon black with the particle diameter of 30-45nm; the monofilament diameter of the carbon fiber is 6.5 μm, and the length-diameter ratio is 2-15; the grain diameter of the silicon carbide is 1.3-1.5 μm;

slowly cooling the mixed slurry to room temperature, and performing vacuum freeze-drying to obtain a freeze-dried substance; and (3) freeze-grinding the freeze-dried substance, and sieving the ground substance for 4 times by using a 200-mesh sieve after grinding to obtain the conductive micro powder for the polymer-based PTC material, wherein the average particle size is 28 microns.

Example 11

1) Weighing 300g of ethylene-vinyl acetate copolymer (the VA content is 40%), 30g of sodium dodecyl sulfate, 18g of OP-10 and 40g of amine oleate, placing the materials in a reaction kettle, heating to 90 ℃ to completely melt the ethylene-vinyl acetate copolymer, and uniformly stirring; the melting point of the ethylene-vinyl acetate copolymer (VA content 40%) is 70 ℃;

then, slowly adding 500mL of deionized water at 90 ℃ into the reaction kettle, and then dispersing at high speed for 0.5h at 90 ℃ at a rotating speed of 750r/min to completely emulsify the ethylene-vinyl acetate copolymer to obtain a crystalline polymer emulsion;

2) Continuously maintaining the temperature of the reaction kettle at 90 ℃, adding 130g of graphene two-dimensional carbon material, 100g of superconducting carbon black, 85g of carbon fiber and 120g of silicon carbide into the reaction kettle, and then continuously dispersing for 1 hour at 90 ℃ and uniformly mixing to obtain mixed slurry; the graphene two-dimensional carbon material is multilayer graphene oxide, and the sheet diameter is 0.8-5 mu m; the superconducting carbon black is Keqin black with particle size of 35-70nm; the monofilament diameter of the carbon fiber is 5 mu m, and the length-diameter ratio is 2-15; the grain diameter of the silicon carbide is 1.3-1.5 mu m;

slowly cooling the mixed slurry to room temperature, and performing vacuum freeze-drying to obtain a freeze-dried substance; and (3) freeze-grinding the freeze-dried substance, and sieving the ground substance for 4 times by using a 200-mesh sieve after grinding to obtain the conductive micro powder for the polymer-based PTC material, wherein the average particle size is 21 mu m.

Example 12

1) Weighing 350g of stearic acid, 50g of polyvinyl alcohol and 30g of stearic acid monoglyceride, placing the stearic acid, the polyvinyl alcohol and the stearic acid monoglyceride into a reaction kettle, heating to 80 ℃ to completely melt the stearic acid, and uniformly stirring; the melting point of the stearic acid is 60-65 ℃;

then, slowly adding 500mL of deionized water at 85 ℃ into the reaction kettle, and dispersing at a high speed of 600r/min for 0.5h at 80 ℃ to completely emulsify stearic acid;

2) After complete emulsification, adding 120g of graphene two-dimensional carbon material, 80g of superconducting carbon black, 100g of carbon fiber and 100g of aluminum nitride into the reaction kettle, and continuously dispersing for 1h at a high temperature to obtain mixed slurry; the adopted graphene two-dimensional carbon material is multilayer graphene with the sheet diameter of 0.5-3 mu m; the superconducting carbon black is acetylene carbon black with the particle size of 30-45nm; the monofilament diameter of the carbon fiber is 2.6 μm, and the length-diameter ratio is 2-15; the grain diameter of the aluminum nitride is 3-5 μm;

slowly cooling the mixed slurry to room temperature, and performing vacuum freeze-drying to obtain a freeze-dried substance; and (3) freeze-grinding the freeze-dried substance, and sieving the ground substance for 4 times by using a 200-mesh sieve after grinding to obtain the conductive micro powder for the polymer-based PTC material, wherein the average particle size is 27 mu m.

Example 13

The PTC self-temperature-control coating comprises resin emulsion, conductive micro powder, a BYK-024 organic silicon defoamer, a BYK-349 organic silicon leveling agent and other auxiliaries; the resin emulsion is a Dow YS-3018 aqueous polyurethane dispersion, the solid content is 45%, and the softening point of a polymer formed after the resin emulsion is cured in the PTC self-temperature-control coating is more than 90 ℃. The conductive micro powder is the conductive micro powder for the polymer-based PTC material prepared in the embodiment 7, and other auxiliary agents are a Dezhong N-2496 aqueous thickener and a Jiangsu Feiyan chemical KY616-3 hindered phenol antioxidant; the mass ratio of polyethylene oxide, BYK-024 organic silicon defoamer, BYK-349 organic silicon flatting agent and other auxiliary agents contained in the polyurethane emulsion and the conductive micro powder is 1000.

The preparation method of the PTC self-temperature-control coating of the embodiment comprises the following steps: and adding the conductive micro powder into the resin emulsion, then adding the BYK-024 organic silicon defoamer, the BYK-349 organic silicon flatting agent and other auxiliaries, dispersing at room temperature for 0.5h, and uniformly mixing to obtain the PTC self-temperature-control coating.

Example 14

The PTC self-temperature-control coating of the embodiment is prepared from resin emulsion, conductive micro powder, BYK-067A organic silicon defoamer, BYK-380 acrylic leveling agent and other auxiliary agents; the resin emulsion is Qingdao ancient chemical 8912 silicone-acrylate emulsion, the solid content is 45 percent, the softening point of a polymer formed after the resin emulsion is cured in the PTC self-temperature-control coating is more than 105 ℃, the conductive micro powder is the conductive micro powder for the polymer-based PTC material prepared by the preparation method of the embodiment 8, and other auxiliary agents are a Delzhong N-2496 aqueous thickening agent and a Jiangsu Feiya chemical KY616-3 hindered phenol antioxidant; the mass ratio of the polyethylene wax in the acrylic emulsion and the conductive micro powder, the BYK-067A organic silicon defoaming agent, the BYK-380 acrylic acid leveling agent and other auxiliary agents is 1000.

The preparation method of the PTC self-temperature-control coating of the embodiment comprises the following steps: and adding the conductive micro powder into the resin emulsion, then adding a BYK-067A organic silicon defoamer, a BYK-380 acrylic acid flatting agent and other auxiliaries, dispersing at room temperature for 0.5h, and uniformly mixing to obtain the PTC self-temperature-control coating.

Example 15

The PTC self-temperature-control coating of the embodiment consists of resin emulsion, conductive micro powder, BYK-028 organic silicon defoamer, BYK-333 polyether modified organic silicon flatting agent and other auxiliaries; the resin emulsion is Dow RSN-8016 organic silicon resin, the solid content is 60%, the softening point of a polymer formed by the resin emulsion after the PTC self-temperature-control coating is cured is more than 95 ℃, the conductive micro powder is the conductive micro powder for the polymer-based PTC material prepared by the preparation method of the embodiment 9, and other auxiliary agents are a German-Zhongn-2447 organic silicon thickener and a Jiangsu Feiyan chemical KY616-3 hindered phenol antioxidant; the weight ratio of the ethylene-vinyl acetate copolymer in the organic silicon emulsion and the conductive micro powder, BYK-028 organic silicon defoamer, BYK-333 polyether modified organic silicon flatting agent and other auxiliary agents is 1000.

The preparation method of the PTC self-temperature-control coating of the embodiment comprises the following steps: and adding the conductive micro powder into the resin emulsion, then adding a BYK-028 organic silicon defoaming agent, a BYK-333 polyether modified organic silicon flatting agent and other auxiliaries, dispersing at room temperature for 0.5h, and uniformly mixing to obtain the PTC self-temperature-control coating.

Example 16

The PTC self-temperature-control coating of the embodiment consists of resin emulsion, conductive micro powder, a BYK-024 organic silicon defoamer, a BYK-349 organic silicon flatting agent and other auxiliaries; the adopted resin emulsion is a Dow Yitouda TM2468A pure acrylic emulsion, the solid content is 50.5 percent, and the softening point of a polymer formed by the resin emulsion after the PTC self-temperature-control coating is cured is more than 80 ℃; the adopted conductive micro powder is the conductive micro powder for the polymer-based PTC material prepared in the embodiment 10, and the adopted other auxiliary agents are a Dezhong N-2496 aqueous thickening agent and a Jiangsu Feiyan chemical KY616-3 hindered phenol antioxidant; the mass ratio of polyethylene glycol 20000, BYK-024 organic silicon defoamer, BYK-349 organic silicon flatting agent and other auxiliary agents in the acrylic emulsion and the conductive micro powder is 1000.

The preparation method of the PTC self-temperature-control coating of the embodiment comprises the following steps: and adding the conductive micro powder into the resin emulsion, then adding a BYK-024 organic silicon defoaming agent, a BYK-349 organic silicon flatting agent and other auxiliaries, dispersing at room temperature for 0.5h, and uniformly mixing to obtain the PTC self-temperature-control coating.

Example 17

The PTC self-temperature-control coating of the embodiment consists of resin emulsion, conductive micro powder, a BYK-067A organic silicon defoaming agent, a BYK-380 acrylic acid leveling agent and other auxiliary agents; the adopted resin emulsion is Dow Yilingda TM2468A pure acrylic emulsion, the solid content is 50.5 percent, and the softening point of a polymer formed by the resin emulsion after the PTC self-temperature-control coating is cured is more than 80 ℃; the conductive fine powder used was the conductive fine powder for the polymer-based PTC material prepared in example 11; the adopted other auxiliary agents are Dezhong N-2496 aqueous thickening agent and Jiangsu Feiyan chemical KY616-3 hindered phenol antioxidant; the mass ratio of the ethylene-vinyl acetate copolymer in the acrylic emulsion and the conductive micro powder, the BYK-067A organic silicon defoaming agent, the BYK-380 acrylic acid leveling agent and other auxiliary agents is 1000.

The preparation method of the PTC self-temperature-control coating comprises the following steps: and adding the conductive micro powder into the resin emulsion, then adding a BYK-067A organic silicon defoaming agent, a BYK-380 acrylic acid leveling agent and other auxiliaries, dispersing at room temperature for 0.5h, and uniformly mixing to obtain the PTC self-temperature-control coating.

Example 18

The PTC self-temperature-control coating of the embodiment consists of resin emulsion, conductive micro powder, BYK-028 organic silicon defoamer, BYK-333 polyether modified organic silicon flatting agent and other additives; the adopted resin emulsion is JH7506 organic silicon resin in Guangzhou Jia trench chemical technology, the solid content is 50 percent, and the softening point of a polymer formed by the resin emulsion after the PTC self-temperature-control coating is cured is more than 65 ℃; the conductive fine powder used was the conductive fine powder for the polymer-based PTC material prepared in example 12; the adopted other auxiliary agents are Dezhong N-2447 organic silicon thickening agent and Jiangsu Feiyan chemical KY616-3 hindered phenol antioxidant; the mass ratio of stearic acid, BYK-028 organic silicon defoamer, BYK-333 polyether modified organic silicon flatting agent and other auxiliary agents in the organic silicon emulsion and the conductive micro powder is 1000.

The preparation method of the PTC self-temperature-control coating of the embodiment comprises the following steps: and adding the conductive micro powder into the resin emulsion, then adding a BYK-028 organic silicon defoamer, a BYK-333 polyether modified organic silicon flatting agent and other auxiliaries, dispersing at room temperature for 0.5h, and uniformly mixing to obtain the PTC self-temperature-control coating.

Comparative example 1

The preparation method of the conductive fine powder of the comparative example includes the steps of:

1) Weighing 300g of thermoplastic polyurethane elastomer rubber (TPU), 30g of sodium dodecyl sulfate, 20g of OP-10 and 30g of caprylic capric glyceride, placing the materials in a reaction kettle, heating to 115 ℃ to completely melt the TPU, and uniformly stirring; the melting point of the adopted TPU is 98 ℃;

slowly adding 500mL of deionized water at 100 ℃ into a reaction kettle with the temperature maintained at 115 ℃, pressurizing the reaction kettle for 3-6MPa, and then dispersing at the temperature of 115 ℃ at a high speed of 600r/min for 0.5h to completely emulsify TPU;

2) Continuously maintaining the temperature of the reaction degree at 115 ℃, adding 150g of graphene two-dimensional carbon material, 100g of superconducting carbon black, 50g of carbon fiber and 100g of silicon carbide into the reaction kettle, and then continuously dispersing for 1 hour at 115 ℃ to uniformly mix to obtain mixed slurry; the graphene two-dimensional carbon material is multilayer graphene oxide, the sheet diameter of the graphene is 0.8-5 mu m, the superconducting carbon black is acetylene carbon black, and the particle diameter is 30-45nm; the monofilament diameter of the carbon fiber is 5 mu m, and the length-diameter ratio is 2-15; the grain diameter of the silicon carbide is 1.3-1.5 mu m;

slowly cooling the mixed slurry to room temperature, and then performing vacuum freeze-drying to obtain a freeze-dried substance; and (3) sieving the ground material for 4 times by using a 200-mesh sieve after grinding to obtain the conductive micro powder for the polymer-based PTC material, wherein the average particle size is 24 mu m.

Comparative example 2

1) Weighing 300g of thermoplastic polyurethane elastomer rubber (TPU), 30g of sodium dodecyl sulfate, 20g of OP-10 and 30g of caprylic capric glyceride, placing the materials in a reaction kettle, heating to 80 ℃ to completely melt the TPU, and uniformly stirring; the melting point of the adopted TPU is 60 ℃;

slowly adding 500mL of deionized water at 85 ℃ into a reaction kettle with the temperature maintained at 115 ℃, pressurizing the reaction kettle for 3-6MPa, and then dispersing at the temperature of 115 ℃ at a high speed of 600r/min for 0.5h to completely emulsify TPU;

2) Continuously maintaining the temperature of the reaction degree at 85 ℃, adding 150g of graphene two-dimensional carbon material, 80g of superconducting carbon black, 50g of carbon fiber and 110g of silicon carbide into the reaction kettle, and then continuously dispersing for 1 hour at 85 ℃ and uniformly mixing to obtain mixed slurry; the graphene two-dimensional carbon material is multilayer graphene with the sheet diameter of 5-8 mu m, and the superconducting carbon black is acetylene carbon black with the particle diameter of 30-45nm; the monofilament diameter of the carbon fiber is 6.5 μm, and the length-diameter ratio is 2-15; the grain diameter of the silicon carbide is 1.3-1.5 mu m;

slowly cooling the mixed slurry to room temperature, and then carrying out vacuum freeze-drying to obtain a freeze-dried substance; sieving the ground material for 4 times by using a 200-mesh sieve after grinding to obtain conductive micro powder for the polymer-based PTC material, wherein the average particle size is 28 microns;

comparative example 3

The PCT self-regulating temperature coating of this comparative example differs from the PTC self-regulating temperature coating of example 14 only in that: the conductive fine powder used in this comparative example was the conductive fine powder prepared in comparative example 1.

Comparative example 4

The PCT self-regulating temperature coating of this comparative example differs from the PTC self-regulating temperature coating of example 13 only in that: the conductive micro powder adopted by the comparative example replaces a filler consisting of a graphene two-dimensional carbon material, superconducting carbon black, carbon fibers and aluminum nitride, and the mass ratio of the graphene two-dimensional carbon material to the superconducting carbon black to the carbon fibers to the aluminum nitride is 150; the graphene-based two-dimensional carbon material, the superconducting carbon black, the carbon fiber and the aluminum nitride used were the same as in example 7.

Comparative example 5

The PCT self-regulating temperature coating of this comparative example differs from the PTC self-regulating temperature coating of example 17 only in that: the conductive fine powder used in this comparative example was the conductive fine powder prepared in comparative example 2.

Experimental example 1

The PTC self-temperature-control paints of examples 13 to 15 and comparative examples 1 to 2 were prepared by screen printing using an electric heating film having a length × width × thickness of 115mm × 45.75mm × 30 μm, both sides (115 mm × 30 μm sides) were coated with conductive silver paste, and subjected to a temperature resistance test at room temperature-110 ℃ and a plurality of energization tests, and the data obtained are shown in fig. 1 and table 1.

TABLE 1 test results of temperature resistance test and multiple power-on test

Experimental example 2

The PTC self-temperature-control paints of examples 16 to 18 and comparative examples 2 to 3 were respectively prepared into an electric heating film having a length × width × thickness of 115mm × 45.75mm × 30 μm by screen printing, both side surfaces (115 mm × 30 μm surfaces) were coated with conductive silver paste, and subjected to a temperature resistance test at room temperature of-70 ℃ and a plurality of energization tests, and the data obtained are shown in fig. 2 and table 2.

TABLE 2 test results of temperature resistance test and multiple energization test

Claims

1. A conductive fine powder for a polymer-based PTC material, characterized in that: the solid filler comprises a solid filler for a polymer-based PTC material and a crystalline organic layer coated on the surface of the solid filler for the polymer-based PTC material; the solid filler for the polymer-based PTC material comprises a conductive carbon material; the main component of the crystalline organic matter layer is crystalline organic matter, and the mass ratio of the conductive carbon material to the crystalline organic matter is 10-120; the grain diameter of the conductive micro powder is less than or equal to 80 mu m.

2. The conductive fine powder for a polymer-based PTC material according to claim 1, wherein: the melting point of the crystalline organic matter is T, and T is more than or equal to 40 ℃ and less than 80 ℃ or T is more than or equal to 80 ℃; t is more than or equal to 40 ℃ and less than 80 ℃, and the crystalline organic matter is crystalline polymer and/or non-polymeric crystalline organic matter; when T is more than or equal to 80 ℃, the crystalline organic matter is a crystalline polymer.

3. The conductive fine powder for a polymer-based PTC material according to claim 2, wherein: t is more than or equal to 40 ℃ and less than 80 ℃, the crystalline polymer is one or any combination of polyethylene glycol, ethylene-vinyl acetate copolymer, oxidized polyethylene wax and polycaprolactone, and the non-polymer crystalline organic matter is one or any combination of palmitic acid, lauric acid and 12-hydroxystearic acid;

or T is more than or equal to 80 ℃ and less than or equal to 120 ℃, and the crystalline polymer is one or any combination of polyethylene, polyethylene wax, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-acrylic acid copolymer, polyoxyethylene, polyvinyl chloride and chlorinated polyethylene.

4. A conductive micropowder for polymer-based PTC material according to claim 1, characterized in that: the conductive carbon material is a graphene two-dimensional carbon material, superconducting carbon black and carbon fiber; the mass ratio of the graphene two-dimensional carbon material to the superconducting carbon black to the carbon fiber to the crystalline organic matter is 5-30; the sheet diameter of the graphene two-dimensional carbon material is 300nm-15 mu m; the grain diameter of the superconducting carbon black is 35-300nm; the monofilament diameter of the carbon fiber is 1-10 μm, and the length-diameter ratio is 2-15; the average grain diameter of the conductive micro powder is 10-30 mu m.

5. The conductive fine powder for a polymer-based PTC material according to claim 4, wherein: the graphene two-dimensional carbon material is one or any combination of single-layer graphene, multi-layer graphene and graphene oxide; the superconducting carbon black is acetylene carbon black and/or ketjen black.

6. The conductive fine powder for a polymer-based PTC material according to any one of claims 1 to 4, wherein: the solid filler for the polymer-based PTC material also comprises an inorganic heat-conducting filler; the mass ratio of the inorganic heat-conducting filler to the crystalline organic matter is 5-30.

7. A preparation method of conductive micro powder for polymer-based PTC material is characterized in that: the method comprises the following steps: drying the mixed slurry into solid, and then crushing into micro powder;

the mixed slurry is obtained by dispersing solid fillers for the polymer-based PTC material in crystalline organic emulsion; the solid filler for the polymer-based PTC material comprises a conductive carbon material; the mass ratio of the conductive carbon material to the crystalline organic matter in the crystalline organic matter emulsion is 10-120; the particle size of the conductive micro powder is less than or equal to 80 mu m.

8. The method for preparing conductive fine powder for polymer-based PTC material according to claim 7, wherein: the melting point of the crystalline organic matter is T, and T is more than or equal to 40 ℃ and less than 80 ℃ or T is more than or equal to 80 ℃; t is more than or equal to 40 ℃ and less than 80 ℃, and the crystalline organic matter is a crystalline polymer and/or a non-polymer crystalline organic matter; when T is more than or equal to 80 ℃, the crystalline organic matter is a crystalline polymer.

9. The method for preparing conductive fine powder for polymer-based PTC material according to claim 8, wherein: t is more than or equal to 40 ℃ and less than 80 ℃, the crystalline polymer is one or any combination of polyethylene glycol, ethylene-vinyl acetate copolymer, oxidized polyethylene wax and polycaprolactone, and the non-polymer crystalline organic matter is one or any combination of palmitic acid, lauric acid and 12-hydroxystearic acid;

10. The method for preparing conductive fine powder for polymer-based PTC material according to claim 7, wherein: the conductive carbon material comprises the following components in parts by weight: 5-30 parts of graphene two-dimensional carbon material, 5-40 parts of superconducting carbon black and 0-50 parts of carbon fiber; the mass ratio of the graphene two-dimensional carbon material to the crystalline organic matter is 5-30; the sheet diameter of the graphene two-dimensional carbon material is 300nm-15 mu m; the grain diameter of the superconducting carbon black is 30-300nm; the monofilament diameter of the carbon fiber is 1-10 μm, and the length-diameter ratio is 2-15; the average grain diameter of the conductive micro powder is 10-30 mu m.

11. The method for preparing conductive fine powder for polymer-based PTC material according to claim 10, wherein: the superconducting carbon black is acetylene carbon black and/or ketjen black; the graphene two-dimensional carbon material is one or any combination of single-layer graphene, multi-layer graphene and graphene oxide.

12. The method for preparing conductive fine powder for polymer-based PTC material according to claim 7, wherein: the crystalline organic substance emulsion is formed by dispersing a crystalline organic substance in water; the preparation method of the crystalline organic substance emulsion comprises the following steps: heating the crystalline organic matter, the emulsifying agent and the dispersing agent to a temperature higher than the melting point of the crystalline organic matter, melting and uniformly mixing, and then adding water to carry out dispersion and emulsification under set pressure and set temperature to obtain the composite material; the boiling point of water at the set pressure is not lower than the melting point of the crystalline organic substance, and the set temperature is not higher than the boiling point of water at the set pressure.

13. The method for preparing conductive fine powder for a polymer-based PTC material according to claim 12, wherein: the emulsifier is an anionic emulsifier and/or a nonionic emulsifier; the anionic emulsifier is one or any combination of alkyl sulfate, alkyl sulfonate and alkyl benzene sulfonate; the non-ionic emulsifier is one or any combination of alkylphenol polyoxyethylene ether emulsifier, sorbitan fatty acid ester emulsifier and polyoxyethylene sorbitan fatty acid ester emulsifier; the dispersing agent is one or any combination of fatty acid dispersing agent, fatty amide dispersing agent and glyceride dispersing agent.

14. The method for preparing conductive fine powder for polymer-based PTC material according to claim 7, wherein: the solid filler for the polymer-based PTC material also comprises an inorganic heat-conducting filler, wherein the mass ratio of the inorganic heat-conducting filler to the crystalline organic matter in the crystalline organic matter emulsion is (5-30); the particle size of the inorganic heat-conducting filler is 50 nm-5 mu m.

15. The method for preparing conductive fine powder for polymer-based PTC material according to claim 14, wherein: the inorganic heat conducting filler is selected from one or any combination of silicon carbide, silicon dioxide, boron nitride and aluminum nitride.

16. A PTC temperature self-control coating is characterized in that: comprises resin emulsion, conductive micro powder and additive which are dispersed in the resin emulsion; the conductive fine powder is the conductive fine powder for polymer-based PTC materials according to any one of claims 1 to 6 or the conductive fine powder for polymer-based PTC materials prepared by the preparation method according to any one of claims 7 to 15.

17. A PTC self temperature controlling coating according to claim 16, wherein: the mass ratio of the solid matters in the resin emulsion to the crystalline organic matters in the conductive micro powder is 30-60.

18. A PTC self temperature controlling coating according to claim 16, wherein: the resin emulsion is one or any combination of polyurethane emulsion, acrylic emulsion, acrylate emulsion, organic silicon emulsion and epoxy resin emulsion; the solid content of the resin emulsion is 30-60%.

19. A PTC self temperature controlling coating according to claim 16, wherein: the additive comprises a defoaming agent and a leveling agent; the mass ratio of the defoaming agent to the leveling agent to the resin emulsion is 3-50; the defoaming agent is an organic silicon defoaming agent and/or a polyether modified organic silicon defoaming agent; the leveling agent is one or any combination of an acrylic leveling agent, an acrylate leveling agent and an organic silicon leveling agent.