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

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

A kind of conductive micropowder for polymer base PTC material and preparation method thereof, PTC self-contained Temperature Control Coating

technical field

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

Background technique

PTC (positive temperature coefficient) material, that is, positive temperature coefficient material, the resistance will show a nonlinear change with the increase of temperature, and it will self-regulate along a specific transformation curve. The resistivity can jump by multiple orders of magnitude in a specific temperature range. Complete the transition from conductive or semiconductive materials to insulating materials. This special temperature response ability gives it a switch response characteristic, which has a wide range of applications in smart home, electrothermal sensing, thermal insulation buildings, new energy lithium batteries and other fields. Among them, PTC materials are divided into two categories: ceramic-based PTC materials and polymer-based PTC materials. Ceramic-based PTC materials mainly depend on the increase or decrease of resistivity induced by the change of material grain boundary barrier at different temperatures. Usually, different types and proportions of donor elements and acceptor elements are added to complete the resistivity and The control of PTC characteristics, the current PTC material technology based on ceramic base has been perfected, and a series of temperature control products can be seen in the market.

Compared with ceramic-based PTC materials, polymer PTC materials have the advantages of easy availability of raw materials, cheap price, light weight, easy processing and preparation, and low room temperature resistivity. At the same time, they also have many excellent properties of polymer materials, so they are increasingly popular. focus on. The self-temperature control characteristic of polymer-based PTC materials comes from the destruction of the conductive network caused by the thermal expansion of the resin matrix, and the service temperature of polymer-based PTC materials is affected by the glass transition temperature and melting point of the polymer matrix. The common polymer-based PTC materials on the market are mainly composite materials formed by filling a certain amount of carbon-based conductive fillers in the polymer. They are mainly medium and low temperature electric heating series products. The temperature control temperature is generally ≤80°C, and the high temperature is mostly ceramics. PTC-based materials cannot be made into coatings, and their applications are limited in many occasions. In addition, judging from the current industrialized products, most PTC self-temperature-controlling components often exist in three-dimensional blocks and are hard in texture, which greatly limits their application in complex or narrow areas. The PTC coating has the characteristics of flexible use, which can get rid of the restrictions of the use environment on PTC materials. For example, the Chinese invention patent application with document number CN108912990A discloses a water-based PTC nano-carbon electrothermal coating, which is composed of conductive carbon material, polymer powder, additives, water-based adhesive resin and water. The basic composition and weight percentage are: Conductive carbon material 1-20%, polymer micropowder 2-15%, additive 1-10%, water-based binder resin 10-30%, and the balance is water; the polymer micropowder is crystalline thermoplastic polymer powder, The particle size is 200 nanometers to 5 microns, or any one or combination of polyethylene, polypropylene, nylon, polyethylene terephthalate, polybutylene terephthalate, and polyoxymethylene. The water-based PTC nano-carbon electrothermal coating utilizes the crystallization-softening transition in the thermal cycle of crystalline thermoplastic polymers to drive the change of the nano-carbon conductive network, thereby changing the internal resistance of the coating, obtaining the positive temperature resistance (PTC) effect, and realizing the electric resistance. The regulation of heating paint power can obtain safe and efficient electric heating coating. However, it uses conductive carbon material and polymer micropowder to add to the system independently during the preparation of the coating. The highest PTC strength can only reach 5. When the voltage is unstable or the local temperature rises, thermal runaway is easy to occur, which is very important for its safety. Unfavorable; and in the PTC electrothermal coating, the crystallization-softening transition is used as the main factor to regulate the conductive network. When the temperature tends to the softening point or melting point of the polymer, the polymer molecules connected to each other undergo thermal deformation, the molecular chain moves violently, and the temperature drops The shrinkage recovery and spatial arrangement recovery of polymers that are connected to each other will be affected, which is not good for the room temperature resistance recovery under long-term use, and problems such as room temperature resistance increase will easily occur in the later period, which will affect its service life.

Contents of the invention

The purpose of the present invention is to provide a conductive micropowder used in polymer-based PTC materials, which can solve the problems that PTC electrothermal coatings are prone to thermal runaway and long-term use is prone to increase in room temperature resistance.

The invention also provides a method for preparing conductive micropowder used in polymer-based PTC materials.

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

In order to achieve the above object, the technical scheme adopted for the conductive micropowder of the polymer-based PTC material of the present invention is:

A conductive micropowder for a polymer-based PTC material, comprising a solid filler for a polymer-based PTC material and a crystalline organic layer coated on the surface of the solid filler for a polymer-based PTC material; the polymer-based PTC material The solid filler includes conductive carbon material; the main component of the crystalline organic layer is crystalline organic matter, and the mass ratio of conductive carbon material to crystalline organic matter is 10-120:10-50; the particle size of the conductive fine powder is ≤ 80 μm.

The conductive micropowder for polymer-based PTC materials of the present invention coats crystalline organic matter on the surface of the conductive carbon material. Reunion, and the crystalline organic matter on the surface of the conductive carbon material has excellent compatibility with the matrix resin, which can promote the uniform dispersion of the conductive carbon material in the coating; on the other hand, due to the barrier effect of the crystalline organic matter, it can make the conductive carbon material The materials are distributed in the resin system in the form of "islands". At room temperature, different types of carbon materials form a rich and dense conductive network with each other, endowing PTC materials with excellent room temperature resistivity and electrothermal properties.

In addition, due to the special structural relationship between the conductive carbon material and the crystalline organic matter in the conductive micropowder of the present invention, the NTC phenomenon of the polymer-based PTC material can be significantly suppressed, and the safety of the polymer-based PTC material can be improved. This is because the coating structure makes The crystalline organic matter exists in the form of "islands", and in most cases, it is independently distributed in the resin matrix, with only a small amount of bonding; therefore, even if the temperature is locally increased, the molten crystalline organic matter will be firmly fixed by the matrix resin. In its narrow space, it inhibits the rearrangement of conductive carbon materials to form a new conductive network, thereby effectively inhibiting the NTC phenomenon of polymer-based PTC materials and improving their electrical recovery. At the same time, because the crystalline organic matter is coated on the surface of the conductive carbon material, a slight expansion can force the adjacent carbon materials to separate, thereby causing the destruction of the conductive network and providing it with a higher PTC strength.

Further, the melting point of the crystalline organic matter is T, 40°C≤T<80°C or T≥80°C; when 40°C≤T<80°C, the crystalline organic matter is a crystalline polymer and/or a non-polymer Type crystalline organic matter; when T≥80°C, the crystalline organic matter is a crystalline polymer.

Further, 40°C≤T<80°C, the crystalline polymer is polyethylene glycol (PEG), ethylene-vinyl acetate copolymer (EVA), oxidized polyethylene wax (OPE), polycaprolactone (PCL) One or any combination of these, the non-polymer crystalline organic matter is one or any combination of palmitic acid, lauric acid, and 12-hydroxystearic acid; or 80°C≤T≤120°C, the crystallization The polymers are 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), chlorinated polyethylene (CPE), or any combination.

Further, the mass ratio of the conductive carbon material to the crystalline organic matter is 42-57:50, for example, 45-56.7:50 or 42.8-52.5:50.

Further, the conductive carbon material is graphene-based two-dimensional carbon material, superconducting carbon black and carbon fiber; the mass ratio of graphene-based two-dimensional carbon material, superconducting carbon black, carbon fiber and crystalline organic matter is 5-30 :5～40:0～50:10～50, preferably 16～30:11～20:5～15:50, such as 16.6～30:13.3～20:5～13.4:50 or 17.1～25:11.4 ~13.4:8.3~14.3:50. The sheet diameter of the graphene-like two-dimensional carbon material is 300nm-15μm; the particle size of the superconducting carbon black is 35-300nm; the monofilament diameter of the carbon fiber is 1-10μm, and the aspect ratio is 2-15 :1.

Further, the particle size of the conductive fine powder is ≤75 μm. The average particle size of the conductive fine powder is 10-30 μm, for example, 21-28 μm.

Further, the graphene-like two-dimensional carbon material is one or any combination of single-layer graphene, multilayer 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 also includes an inorganic thermally conductive filler; the mass ratio of the inorganic thermally conductive filler to the crystalline organic matter is 5-30:10-50, preferably 13-20:50, for example, 13.3 ~20:50 or 14.2~20:50.

The technical scheme adopted in the preparation method of the conductive micropowder for polymer-based PTC material of the present invention is:

A method for preparing conductive micropowder for polymer-based PTC materials, comprising the steps of: drying the mixed slurry into solids, and then crushing into micropowder; the mixed slurry is to disperse the polymer-based PTC materials with solid fillers Obtained from a crystalline organic matter emulsion; the solid filler for the polymer-based PTC material includes a conductive carbon material; the mass ratio of the conductive carbon material to the crystalline organic matter in the crystalline organic matter emulsion is 10-120:10-50; The particle size of the conductive micropowder is ≤80 μm.

The preparation method for the polymer-based PTC material conductive micropowder of the present invention can improve the degree of uniform dispersion of the solid filler for the polymer-based PTC material in the prepared conductive micropowder.

Further, the particle size of the conductive fine powder is ≤75 μm. The average particle size of the conductive fine powder is 10-30 μm, for example, 21-28 μm.

Further, the mass ratio of the conductive carbon material to the crystalline organic matter in the crystalline organic matter emulsion is 27-34:30-35.

Further, the melting point of the crystalline organic matter is T, 40°C≤T<80°C or T≥80°C; when 40°C≤T<80°C, the crystalline organic matter is a crystalline polymer and/or a non-polymer Type crystalline organic matter; when T≥80°C, the crystalline organic matter is a crystalline polymer.

Further, when 40°C≤T<80°C, the crystalline polymer is one or any combination of polyethylene glycol, ethylene-vinyl acetate copolymer, oxidized polyethylene wax, and polycaprolactone, and the non-polymeric The physical form of crystalline organic matter is one or any combination of palmitic acid, lauric acid, and 12-hydroxystearic acid; or 80°C≤T≤120°C, and the crystalline polymer is polyethylene, polyethylene wax, polypropylene , ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-acrylic acid copolymer, polyethylene oxide, polyvinyl chloride, chlorinated polyethylene, or any combination thereof. For example, VA content in ethylene-vinyl acetate copolymer is 28% or 40%. For example, the crystalline polymer is polyethylene glycol with a melting point of 58-63°C, ethylene-vinyl acetate copolymer with a melting point of 70°C, or stearic acid with a melting point of 60-65°C; Ethylene wax, polyethylene oxide with a melting point of 85-90°C or ethylene-vinyl acetate copolymer with a melting point of 95°C.

Further, the conductive carbon material is composed of the following components in parts by weight: 5-30 parts of graphene-based two-dimensional carbon material, 5-40 parts of superconducting carbon black, and 0-50 parts of carbon fiber, that is to say: The conductive carbon material is composed of graphene two-dimensional carbon material, superconducting carbon black and carbon fiber, and the mass ratio of graphene two-dimensional carbon material, superconducting carbon black and carbon fiber is 5-30:5-40:0-50. Further, the mass ratio of graphene two-dimensional carbon material, superconducting carbon black and carbon fiber is 16-30:11-20:5-15:50, for example, 16.6-30:13.3-20:5-13.4:50 Or 17.1～25:11.4～13.4:8.3～14.3:50. The mass ratio of the graphene-based two-dimensional carbon material to the crystalline organic matter is 5-30:10-50, preferably 16-30:50, such as 16.6-30:50 or 17.1-25:50.

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

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

Further, the crystalline organic matter emulsion is formed by dispersing the crystalline organic matter in water; the preparation method of the crystalline organic matter emulsion includes the following steps: heating the crystalline organic matter, emulsifier and dispersant to a temperature above the melting point of the crystalline organic matter and melting and mixing Mix well, then add water to disperse and emulsify under the set pressure and set temperature. The boiling point of water under the set pressure is not lower than the melting point of crystalline organic matter, and the set temperature is not higher than the boiling point of water under the set pressure.

Further, the emulsifier is an anionic emulsifier and/or a nonionic emulsifier; the anionic emulsifier is one of alkyl sulfate, alkyl sulfonate, alkylbenzene sulfonate or Any combination; the alkylsulfate is sodium dodecylsulfate; the alkylsulfonate is sodium dodecylsulfonate; the alkylbenzenesulfonate is sodium dodecylbenzenesulfonate The nonionic emulsifier is one or any combination of alkylphenol polyoxyethylene ether emulsifier, sorbitan fatty acid ester emulsifier, polyoxyethylene sorbitan fatty acid ester emulsifier; The alkylphenol polyoxyethylene ether emulsifier is one or any combination of OP-6, OP-7, OP-8, OP-9; the sorbitan fatty acid ester emulsifier is Span 40, Span60 , Span 80 or any combination; the polyoxyethylene sorbitan fatty acid ester emulsifier is one or any combination of Tween-20, Tween-40, Tween-60.

Further, the dispersant is one or any combination of fatty acid dispersant, aliphatic amide dispersant, glyceride dispersant; the fatty acid dispersant is myristic acid, palmitic acid, stearic acid One of or any combination of; the aliphatic amide dispersant is one or any combination of stearic acid amide, erucamide, oleic acid amide, oleic acid diethanolamide, vinylbisstearamide; The glyceride dispersant is one or any combination of glyceryl caprate, glyceryl dioleate, and monoglyceride stearate.

Further, the solid filler for the polymer-based PTC material also includes an inorganic thermally conductive filler, and the mass ratio of the inorganic thermally conductive filler to the crystalline organic compound in the crystalline organic compound emulsion is 5-30:10-50, preferably 13-50 20:50, for example 13.3-20:50 or 14.2-20:50; the particle size of the inorganic thermally conductive filler is 50nm-5μm, preferably 1.3-5μm, for example 1.3-1.5μm or 3-5μm.

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

The technical scheme adopted by the PTC self-temperature-control coating of the present invention is:

A PTC self-temperature-controlling paint, comprising resin emulsion and conductive micropowder and additives dispersed in the resin emulsion; said conductive micropowder is the above-mentioned conductive micropowder for polymer-based PTC materials or the above-mentioned conductive micropowder for polymer-based PTC materials The preparation method of the micropowder is the conductive micropowder used for polymer-based PTC materials.

The PTC self-temperature control coating of the present invention, compared with the common low-temperature PTC self-temperature control coating, belongs to the high-temperature segment PTC self-temperature control coating, and the electrothermal film formed after coating has good electrical recovery, heat generation stability and low Room temperature resistance, and has excellent high and low temperature stability, no thermal aging even if used for a long time, good self-temperature control effect, high safety in use, and has broad application prospects. The PTC self-temperature-controlling paint of the present invention has a simple preparation process, and only needs to mix the raw materials. The construction process is flexible, easy to print into various shapes, and has good customizable properties.

In particular, the melting point of the crystalline polymer in the conductive micropowder is 80-120°C, and the crystalline polymer is polyethylene, polyethylene wax, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-acrylic acid When one or any combination of copolymers, polyethylene oxide, polyvinyl chloride, and chlorinated polyethylene, the PTC self-temperature-controlling coating of the present invention has good self-temperature-controlling properties between 75-110°C, filling the market Blank on the PTC material temperature range.

Further, the mass ratio of the solid matter in the resin emulsion to the crystalline organic matter in the conductive fine powder is 30-60:10-50, preferably 45-60:30-35.

It can be understood that the resin emulsion of the present invention is an aqueous resin emulsion, and when the resin in the resin emulsion is a 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 that of the conductive micropowder. The melting point of the organic matter; when the resin in the resin emulsion is a thermosetting polymer, the heat distortion temperature of the polymer formed by the resin after the PTC self-temperature control coating is cured is not lower than the melting point of the crystalline organic matter in the conductive micropowder. Further, the resin emulsion is one or any combination of polyurethane emulsion, acrylic emulsion, acrylate emulsion, silicone 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 water-based resin emulsion can be either a one-component water-based resin emulsion or a two-component water-based resin emulsion. It can be understood that the one-component water-based resin emulsion is a self-crosslinking water-based resin emulsion. For example, epoxy resin emulsion and polyurethane emulsion can be two-component or one-component.

Further, the additive includes a defoamer and a leveling agent; the mass ratio of the defoamer, leveling agent and resin emulsion is 3-50:3-50:1000, preferably 5-50:5-50 :1000.

Further, the defoamer is a silicone type defoamer and/or a polyether modified silicone type defoamer; the leveling agent is an acrylic leveling agent, an acrylic leveling agent, a silicone One or any combination of leveling agents; the main component of the acrylic leveling agent is acrylic acid homopolymer and/or acrylic acid copolymer, and the molecular weight of acrylic acid homopolymer and acrylic acid copolymer is 6000～20000; The main component of the silicone leveling agent is polydimethylsiloxane and/or polyether modified polydimethylsiloxane; the main component of the silicone type defoamer is polydimethylsiloxane alkane, the polyether modified silicone defoamer is one or any combination of aminopolyether silicone defoamer, alkoxy polyether silicone defoamer, hydroxyl polyether silicone defoamer .

Further, the defoamer is one or any combination of BYK-024 silicone defoamer, BYK-067A silicone defoamer, BYK-028 silicone defoamer, and the leveling agent is BYK - One or any combination of 349 silicone leveling agent, BYK-380 acrylic leveling agent, BYK-333 polyether modified silicone leveling agent.

Description of drawings

Fig. 1 is the performance test result figure of the electrothermal film that adopts embodiment 13～15 and the PTC self-temperature control coating of comparative example 1～2 to make in experimental example 1;

Fig. 2 is a graph showing the performance test results of the electrothermal film prepared by using the PTC self-temperature-controlling coatings of Examples 16-18 and Comparative Examples 2-3 in Experimental Example 2.

detailed description

The technical solution of the present invention will be further described below in combination with specific embodiments.

Example 1

The conductive micropowder that is used for polymer-based PTC material of the present embodiment comprises the solid filler of polymer-based PTC material and the crystalline organic layer that is coated on the surface of solid filler for polymer-based PTC material; The polymer-based PTC material is solid The filler is graphite-like two-dimensional carbon material, superconducting carbon black, carbon fiber and aluminum nitride, and the mass ratio of graphene-like two-dimensional carbon material, superconducting carbon black, carbon fiber and aluminum nitride is 150:100:30:100. The graphene-like two-dimensional carbon material is multi-layer graphene, with a sheet diameter of 5-8 μm, and the superconducting carbon black is Ketjen Black, with a particle size of 35-70 nm; the single filament diameter of carbon fiber is 6.5 μm, and the aspect ratio is 2-15 : 1; the particle size of aluminum nitride is 3-5 μm; the main component of the crystalline organic layer is polyethylene oxide, and the melting point is 85-90 ° C; the mass ratio of graphite-like two-dimensional carbon material to polyethylene oxide is 150:300 ; The particle size of the conductive micropowder is ≤75 μm, and the average particle size is 26 μm.

The conductive micropowder used in the polymer-based PTC material of this example can be prepared by the method of Example 7.

Example 2

The conductive micropowder that is used for polymer-based PTC material of the present embodiment comprises the solid filler of polymer-based PTC material and the crystalline organic layer that is coated on the surface of solid filler for polymer-based PTC material; The polymer-based PTC material is solid The filler is graphite-like two-dimensional carbon material, superconducting carbon black, carbon fiber and silicon carbide, the mass ratio of graphene-like two-dimensional carbon material, superconducting carbon black, carbon fiber and aluminum nitride is 100:120:50:80, graphite The alkene-based two-dimensional carbon material is multilayer graphene oxide with a sheet diameter of 0.8-5 μm, and the superconducting carbon black is acetylene carbon black with a particle size of 30-45 nm; the monofilament diameter of carbon fiber is 5 μm, and the aspect ratio is 2-15 : 1; the particle size of silicon carbide is 1.3-1.5 μm; the main component of the crystalline organic layer is polyethylene wax, and the melting point is 100-105 ° C; the mass ratio of graphite two-dimensional carbon material to polyethylene wax is 100:300; The particle size of the conductive fine powder is ≤75 μm, and the average particle size is 25 μm.

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

Example 3

The conductive micropowder that is used for polymer-based PTC material of the present embodiment comprises the solid filler of polymer-based PTC material and the crystalline organic layer that is coated on the surface of solid filler for polymer-based PTC material; The polymer-based PTC material is solid The filler is graphite-like two-dimensional carbon material, superconducting carbon black, carbon fiber and silicon carbide, the mass ratio of graphene-like two-dimensional carbon material, superconducting carbon black, carbon fiber and aluminum nitride is 180:80:80:120, graphite The olefinic two-dimensional carbon material is multi-layer graphene, with a sheet diameter of 0.5-3μm, and the superconducting carbon black is acetylene carbon black, with a particle size of 200-240nm; the single filament diameter of carbon fiber is 2.6μm, and the aspect ratio is 2-15: 1. The particle size of aluminum nitride is 3-5μm; the main component of the crystalline organic layer is ethylene-vinyl acetate copolymer (VA content 28%), and the melting point is 95°C; graphite-based two-dimensional carbon material and ethylene-vinyl acetate copolymer The mass ratio of the powder is 180:300; the particle size of the conductive micropowder is ≤75 μm, and the average particle size is 21 μm.

The conductive micropowder used in the polymer-based PTC material of this example can be prepared by the preparation method of Example 9.

Example 4

The conductive micropowder that is used for polymer-based PTC material of the present embodiment comprises the solid filler of polymer-based PTC material and the crystalline organic layer that is coated on the surface of solid filler for polymer-based PTC material; The polymer-based PTC material is solid The filler is graphene-like two-dimensional carbon material, superconducting carbon black, carbon fiber and silicon carbide, and the mass ratio of graphene-like two-dimensional carbon material, superconducting carbon black, carbon fiber and silicon carbide is 150:80:50:110; The graphene-like two-dimensional carbon material is multilayer graphene, with a sheet diameter of 5-8μm; the superconducting carbon black is acetylene carbon black, with a particle size of 30-45nm; the single filament diameter of carbon fiber is 6.5μm, and the aspect ratio is 2-15 : 1; the particle size of silicon carbide is 1.3-1.5 μm; the crystalline organic layer is composed of polyethylene glycol 20000, OP-6, Span80 and glyceryl caprylate, and the melting point of polyethylene glycol is 58-63 ° C; polyethylene glycol The mass ratio of diol and graphene-based two-dimensional carbon material is 300:150. The particle size of the conductive fine powder in this embodiment is ≤75 μm, and the average particle size is 28 μm.

The conductive fine powder used in the polymer-based PTC material of this embodiment can be prepared by the preparation method of Embodiment 10.

Example 5

The conductive micropowder that is used for polymer-based PTC material of the present embodiment comprises the solid filler of polymer-based PTC material and the crystalline organic layer that is coated on the surface of solid filler for polymer-based PTC material; The polymer-based PTC material is solid The filler is graphene-like two-dimensional carbon material, superconducting carbon black and carbon fiber, and the mass ratio of graphene-like two-dimensional carbon material, superconducting carbon black and carbon fiber is 130:100:85:120; graphene-like two-dimensional carbon The material is multilayer graphene oxide with a sheet diameter of 0.8-5μm, the superconducting carbon black is Ketjen black with a particle size of 35-70nm; the monofilament diameter of carbon fiber is 5μm, and the aspect ratio is 2-15:1; silicon carbide The particle size is 1.3-1.5μm; the crystalline organic layer is composed of ethylene-vinyl acetate copolymer (40% VA content), sodium lauryl sulfate, OP-10 and oleic acid amine, and the ethylene-vinyl acetate copolymer The melting point is 70°C; the mass ratio of ethylene-vinyl acetate copolymer to graphene-like two-dimensional carbon material is 300:130. The particle size of the conductive fine powder in this embodiment is ≤75 μm, and the average particle size is 21 μm.

The conductive micropowder used in the polymer-based PTC material of this example can be prepared by the preparation method of Example 11.

Example 6

The conductive micropowder that is used for polymer-based PTC material of the present embodiment comprises the solid filler of polymer-based PTC material and the crystalline organic layer that is coated on the surface of solid filler for polymer-based PTC material; The polymer-based PTC material is solid The filler is graphene-like two-dimensional carbon material, superconducting carbon black, carbon fiber and aluminum nitride, and the mass ratio of graphene-like two-dimensional carbon material, superconducting carbon black, carbon fiber and silicon carbide is 120:80:100:100 ; The graphene-like two-dimensional carbon material is multi-layer graphene, with a sheet diameter of 0.5-3 μm, and the superconducting carbon black is acetylene carbon black, with a particle size of 30-45 nm; the single filament diameter of carbon fiber is 2.6 μm, and the aspect ratio is 2- 15:1; the particle size of aluminum nitride is 3-5μm; the crystalline organic layer is composed of stearic acid, polyvinyl alcohol and monoglyceride stearate, and the melting point of stearic acid is 60-65°C; stearic acid and graphene The mass ratio of the quasi-two-dimensional carbon material is 350:120. The particle size of the conductive fine powder in this embodiment is ≤75 μm, and the average particle size is 27 μm.

The conductive micropowder used in the 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 micropowder that is used for polymer-based PTC material of the present embodiment, comprises the following steps:

1) Weigh 300g of polyethylene oxide, 54g of polyvinyl alcohol, and 30g of monoglyceride stearate in a reactor, heat up to 105°C to completely melt the polyethylene oxide, and stir evenly; the melting point of the polyethylene oxide used is 85-90°C;

Then take 500mL of deionized water at 100°C and slowly add it into the reaction kettle maintained at 105°C, pressurize the reaction kettle to 3-6MPa, and then disperse at 105°C at a speed of 600r/min for 0.5h at a high speed to make polyoxyethylene Complete emulsification to obtain a crystalline polymer emulsion;

2) Continue to maintain the temperature of the reactor at 105°C, add 150g of graphene-based two-dimensional carbon material, 100g of superconducting carbon black, 30g of carbon fiber, and 100g of aluminum nitride into the reactor, and then continue to disperse and mix at 105°C for 1 hour Evenly, mixed slurry is obtained; the graphene-like two-dimensional carbon material used is multi-layer graphene, with a sheet diameter of 5-8 μm; the superconducting carbon black is Ketjen black, with a particle size of 35-70nm; 6.5μm, the aspect ratio is 2-15:1; the particle size of aluminum nitride is 3-5μm;

Slowly cool the mixed slurry to room temperature, vacuum freeze-dry to obtain a freeze-dried product; freeze-dried the freeze-dried product, and use a 200-mesh sieve to sieve the ground product 4 times after grinding to obtain a polymer-based PTC material. Conductive fine powder with a particle size of ≤75 μm and an average particle size of 26 μm.

Example 8

The preparation method of the conductive micropowder that is used for polymer-based PTC material of the present embodiment, comprises the following steps:

1) Weigh 300g of polyethylene wax, 50g of OP-6, 4g of Span80, and 30g of vinyl bisstearamide in a reaction kettle, heat up to 115°C to completely melt the polyethylene wax, and stir evenly; the polyethylene The melting point of wax is 100-105°C;

Then take 500mL of deionized water at 100°C and slowly add it into the reactor at 115°C maintained at a temperature of 115°C, pressurize the reactor at 3-6MPa, and then disperse at 115°C at a speed of 750r/min for 0.5h at a high speed to make polyethylene The wax is completely emulsified to obtain a crystalline polymer emulsion;

2) Continue to maintain the temperature of the reactor at 115°C, add 100g of graphene-based two-dimensional carbon material, 120g of superconducting carbon black, 50g of carbon fiber, and 80g of silicon carbide into the reactor, and then continue to disperse at 115°C for 1 hour and mix well , to obtain a mixed slurry; the graphene-based two-dimensional carbon material used is multilayer graphene oxide, with a sheet diameter of 0.8-5 μm; the superconducting carbon black is acetylene carbon black, with a particle size of 30-45 nm; the monofilament of carbon fiber The diameter is 5 μm, and the aspect ratio is 2-15:1; the particle size of silicon carbide is 1.3-1.5 μm;

Slowly cool the mixed slurry to room temperature, vacuum freeze-dry to obtain a freeze-dried product; freeze-dried the freeze-dried product, and use a 200-mesh sieve to sieve the ground product 4 times after grinding to obtain a polymer-based PTC material. Conductive fine powder with an average particle size of 25 μm.

Example 9

The preparation method of the conductive micropowder that is used for polymer PCT material of the present embodiment, comprises the following steps:

1) Weigh 300g of ethylene-vinyl acetate copolymer (VA content 28%), 40g of sodium lauryl sulfate, 20g of OP-10, and 30g of stearic acid amide in a reaction kettle, and heat up to 100°C to make ethylene-acetic acid The ethylene copolymer is completely melted and stirred evenly; the melting point of the ethylene-vinyl acetate copolymer used is 95°C;

Then take 500mL of deionized water at 100°C and slowly add it into the reactor, pressurize the reactor to 3-6MPa, and then disperse at 100°C at a speed of 700r/min for 0.5h at a high speed to completely emulsify the ethylene-vinyl acetate copolymer. obtaining a crystalline polymer emulsion;

2) Continue to maintain the temperature of the reactor at 100°C, add 180g of graphene, 80g of superconducting carbon black, 80g of carbon fiber, and 120g of aluminum nitride into the reactor, and then continue to disperse at 100°C for 1 hour and mix evenly to obtain a mixed slurry material; the graphene used is multilayer graphene with a sheet diameter of 0.5-3μm; the superconducting carbon black is acetylene carbon black with a particle size of 200-240nm; the monofilament diameter of carbon fiber is 2.6μm, and the aspect ratio is 2 -15:1; the particle size of aluminum nitride is 3-5μm;

Slowly cool the mixed slurry to room temperature, vacuum freeze-dry to obtain a freeze-dried product; freeze-dried the freeze-dried product, and use a 200-mesh sieve to sieve the ground product 4 times after grinding to obtain a polymer-based PTC material. Conductive fine powder with an average particle size of 21 μm.

Example 10

The preparation method of the conductive micropowder that is used for polymer-based PTC material of the present embodiment, comprises the following steps:

1) Weigh 300g of polyethylene glycol, 50g of OP-6, 4g of Span80, and 30g of caprylic capric acid glyceride in a reaction kettle, heat up to 85°C to completely melt the polyethylene glycol, and stir evenly; polyethylene glycol The melting point is 58-63°C;

Then take 500mL of 85°C deionized water and slowly add it into the reaction kettle maintained at 85°C, and then disperse at a high speed of 700r/min at 85°C for 0.5h to completely emulsify the polyethylene glycol to obtain a crystalline polymer emulsion;

2) Continue to maintain the temperature of the reactor at 85°C, add 150g of graphene-based two-dimensional carbon material, 80g of superconducting carbon black, 50g of carbon fiber, and 110g of silicon carbide into the reactor, and then continue to disperse at 85°C for 1 hour and mix well , to obtain a mixed slurry; the graphene-like two-dimensional carbon material used is multilayer graphene with a sheet diameter of 5-8 μm, and the superconducting carbon black is acetylene carbon black with a particle size of 30-45nm; the single filament diameter of the carbon fiber is 6.5 μm, the aspect ratio is 2-15:1; the particle size of silicon carbide is 1.3-1.5μm;

Slowly cool the mixed slurry to room temperature, vacuum freeze-dry to obtain a freeze-dried product; freeze-dried the freeze-dried product, and use a 200-mesh sieve to sieve the ground product 4 times after grinding to obtain a polymer-based PTC material. Conductive fine powder with an average particle size of 28 μm.

Example 11

The preparation method of the conductive micropowder that is used for polymer-based PTC material of the present embodiment, comprises the following steps:

1) Weigh 300g of ethylene-vinyl acetate copolymer (40% VA content), 30g of sodium lauryl sulfate, 18g of OP-10, and 40g of oleic acid amine and place it in a reaction kettle, heat up to 90°C to make ethylene-vinyl acetate The copolymer is completely melted and stirred evenly; the melting point of ethylene-vinyl acetate copolymer (40% VA content) is 70°C;

Then take 500mL of deionized water at 90°C and slowly add it into the reaction kettle, and then disperse at a high speed of 750r/min at 90°C for 0.5h to completely emulsify the ethylene-vinyl acetate copolymer to obtain a crystalline polymer emulsion;

2) Continue to maintain the temperature of the reactor at 90°C, add 130g of graphene-based two-dimensional carbon material, 100g of superconducting carbon black, 85g of carbon fiber, and 120g of silicon carbide into the reactor, and then continue to disperse at 90°C for 1 hour and mix well , to obtain a mixed slurry; the graphene-like two-dimensional carbon material used is multilayer graphene oxide, with a sheet diameter of 0.8-5 μm; the superconducting carbon black is Ketjen black, with a particle size of 35-70nm; the monofilament diameter of the carbon fiber 5μm, the aspect ratio is 2-15:1; the particle size of silicon carbide is 1.3-1.5μm;

Slowly cool the mixed slurry to room temperature, vacuum freeze-dry to obtain a freeze-dried product; freeze-dried the freeze-dried product, and use a 200-mesh sieve to sieve the ground product 4 times after grinding to obtain a polymer-based PTC material. Conductive fine powder with an average particle size of 21 μm.

Example 12

The preparation method of the conductive micropowder that is used for polymer-based PTC material of the present embodiment, comprises the following steps:

1) Weigh 350g of stearic acid, 50g of polyvinyl alcohol, and 30g of monoglyceride stearate in a reaction kettle, heat up to 80°C to completely melt the stearic acid, and stir evenly; the melting point of stearic acid is 60- 65°C;

Then take 500mL of deionized water at 85°C and slowly add it into the reaction kettle, and disperse at a high speed of 600r/min at 80°C for 0.5h to completely emulsify the stearic acid;

2) After the emulsification is complete, add 120g of graphene-based two-dimensional carbon material, 80g of superconducting carbon black, 100g of carbon fiber, and 100g of aluminum nitride into the reactor, and continue to disperse for 1 hour at a high temperature to obtain a mixed slurry; The graphene-like two-dimensional carbon material is multilayer graphene, with a sheet diameter of 0.5-3μm; the superconducting carbon black is acetylene carbon black, with a particle size of 30-45nm; the single filament diameter of carbon fiber is 2.6μm, and the aspect ratio is 2-15 : 1; the particle size of aluminum nitride is 3-5 μm;

Slowly cool the mixed slurry to room temperature, vacuum freeze-dry to obtain a freeze-dried product; freeze-dried the freeze-dried product, and use a 200-mesh sieve to sieve the ground product 4 times after grinding to obtain a polymer-based PTC material. Conductive fine powder with an average particle size of 27μm.

Example 13

The PTC self-temperature control coating of this embodiment is composed of resin emulsion, conductive micropowder, BYK-024 silicone defoamer, BYK-349 silicone leveling agent and other additives; the resin emulsion is Dow YS-3018 waterborne polyurethane The dispersion has a solid content of 45%, and the softening point of the polymer formed after the resin emulsion is cured after the PTC self-temperature control coating is greater than 90°C. The conductive micropowder is the conductive micropowder used for polymer-based PTC materials prepared in Example 7, and other additives are Dezhong N-2496 water-based thickener and Jiangsu Feiya Chemical KY616-3 hindered phenolic antioxidant; polyurethane emulsion , The mass ratio of polyethylene oxide, BYK-024 silicone defoamer, BYK-349 silicone leveling agent, and other additives contained in the conductive micropowder is 1000:300:30:30:10.

The preparation method of the PTC self-temperature control coating in this embodiment includes the following steps: adding conductive fine powder to the resin emulsion, and then adding BYK-024 silicone defoamer, BYK-349 silicone leveling agent and other additives , Disperse and mix at room temperature for 0.5h to obtain a PTC self-temperature-controlling coating.

Example 14

The PTC self-temperature control coating of the present embodiment is made of resin emulsion, conductive micropowder, BYK-067A organic silicon defoamer, BYK-380 acrylic leveling agent and other auxiliary agents; the resin emulsion is Qingdao Gudao Chemical 8912 silicon acrylic emulsion, solid The content is 45%, the softening point of the polymer formed by the resin emulsion after the PTC self-temperature control coating is cured is> 105 ° C, and the conductive fine powder is the conductive fine powder for polymer-based PTC materials prepared by the preparation method of Example 8, Other additives are Dezhong N-2496 water-based thickener and Jiangsu Feiya Chemical KY616-3 hindered phenolic antioxidant; acrylic emulsion, polyethylene wax in conductive micropowder, BYK-067A silicone defoamer, BYK-380 The mass ratio of acrylic leveling agent to other additives is 1000:300:20:20:10.

The preparation method of the PTC self-temperature-control coating in this embodiment includes the following steps: adding conductive fine powder to the resin emulsion, and then adding BYK-067A silicone defoamer, BYK-380 acrylic leveling agent and other additives, Disperse and mix at room temperature for 0.5h to obtain a PTC self-temperature-controlling coating.

Example 15

The PTC self-temperature control coating in this embodiment is composed of resin emulsion, conductive micropowder, BYK-028 silicone defoamer, BYK-333 polyether modified silicone leveling agent and other additives; the resin emulsion is Dow RSN- 8016 silicone resin, the solid content is 60%, the softening point of the polymer formed by the resin emulsion after the PTC self-temperature control coating is cured is >95°C, and the conductive micropowder is prepared by the preparation method of Example 9 for polymer-based Conductive micropowder of PTC materials, other additives are Dezhong N-2447 silicone thickener, Jiangsu Feiya chemical KY616-3 hindered phenolic antioxidant; silicone emulsion, ethylene-vinyl acetate copolymer in conductive micropowder, BYK The mass ratio of -028 silicone defoamer, BYK-333 polyether modified silicone leveling agent and other additives is 1000:300:15:15:10.

The preparation method of the PTC self-temperature control coating in this embodiment includes the following steps: adding conductive micropowder to the resin emulsion, and then adding BYK-028 silicone defoamer and BYK-333 polyether modified silicone leveling agent And other additives, disperse and mix at room temperature for 0.5h to get PTC self-temperature control coating.

Example 16

The PTC self-temperature control coating in this embodiment is composed of resin emulsion, conductive micropowder, BYK-024 organic silicon defoamer, BYK-349 organic silicon leveling agent and other additives; the resin emulsion used is Dow Easy Tough TM2468A pure acrylic emulsion, with a solid content of 50.5%, the softening point of the polymer formed by the resin emulsion after the PTC self-temperature control coating is cured > 80°C; the conductive powder used is the polymer-based PTC prepared in Example 10 Conductive micropowder of materials, other additives used are Dezhong N-2496 water-based thickener and Jiangsu Feiya chemical KY616-3 hindered phenolic antioxidant; acrylic emulsion, polyethylene glycol 20000 in conductive micropowder, BYK- The mass ratio of 024 silicone defoamer, BYK-349 silicone leveling agent and other additives is 1000:300:3:3:10.

The preparation method of the PTC self-temperature control coating in this embodiment includes the following steps: adding conductive fine powder into the resin emulsion, and then adding BYK-024 silicone defoamer, BYK-349 silicone leveling agent and other additives, Disperse and mix at room temperature for 0.5h to obtain a PTC self-temperature-controlling coating.

Example 17

The PTC self-temperature-controlling paint in this embodiment is composed of resin emulsion, conductive micropowder, BYK-067A silicone defoamer, BYK-380 acrylic leveling agent and other additives; the resin emulsion used is Dow Yida TM2468A Pure acrylic emulsion, the solid content is 50.5%, the softening point of the polymer formed by the resin emulsion after the PTC self-temperature control coating is cured> 80 ℃; Conductive micropowder of materials; other additives used are Dezhong N-2496 water-based thickener and Jiangsu Feiya Chemical KY616-3 hindered phenolic antioxidant; acrylic emulsion, ethylene-vinyl acetate copolymer in conductive micropowder, BYK The mass ratio of -067A silicone defoamer, BYK-380 acrylic leveling agent and other additives is 1000:300:4:3.5:10.

The preparation method of the PTC self-temperature control coating of this embodiment includes the following steps: adding conductive fine powder into the resin emulsion, and then adding BYK-067A silicone defoamer, BYK-380 acrylic leveling agent and other additives, Disperse and mix at room temperature for 0.5h to obtain a PTC self-temperature-controlling coating.

Example 18

The PTC self-temperature control coating in this embodiment is composed of resin emulsion, conductive micropowder, BYK-028 silicone defoamer, BYK-333 polyether modified silicone leveling agent and other additives; the resin emulsion used is Guangzhou Jiahao Chemical Technology JH7506 silicone resin, the solid content is 50%, the softening point of the polymer formed after the resin emulsion is cured by the PTC self-temperature control coating is >65°C; the conductive micropowder used is prepared in Example 12 for Conductive micropowder of polymer-based PTC materials; other additives used are Dezhong N-2447 silicone thickener, Jiangsu Feiya Chemical KY616-3 hindered phenolic antioxidant; silicone emulsion, stearin in conductive micropowder The mass ratio of acid, BYK-028 silicone defoamer, BYK-333 polyether modified silicone leveling agent and other additives is 1000:350:5:3:10.

The preparation method of the PTC self-temperature control coating of this embodiment includes the following steps: adding conductive micropowder to the resin emulsion, and then adding BYK-028 silicone defoamer, BYK-333 polyether modified silicone leveling agent and For other additives, disperse and mix at room temperature for 0.5h to obtain a PTC self-temperature-controlling coating.

Comparative example 1

The preparation method of the conductive micropowder of this comparative example comprises the following steps:

1) Weigh 300g of thermoplastic polyurethane elastomer rubber (TPU), 30g of sodium dodecylsulfonate, 20g of OP-10, and 30g of glyceryl caprylate and place it in a reaction kettle, heat up to 115°C to completely melt the TPU, and Stir evenly; the melting point of the TPU used is 98°C;

Take 500mL of deionized water at 100°C and slowly add it into the reaction kettle maintained at 115°C, then pressurize the reaction kettle to 3-6MPa, and then disperse at 115°C at a speed of 600r/min for 0.5h at a high speed to completely emulsify the TPU;

2) Continue to maintain the reaction temperature at 115°C, add 150g of graphene-based two-dimensional carbon material, 100g of superconducting carbon black, 50g of carbon fiber, and 100g of silicon carbide into the reactor, and then continue to disperse at 115°C for 1 hour and mix well , to obtain a mixed slurry; the graphene-like two-dimensional carbon material is multilayer graphene oxide, and the graphene sheet diameter is 0.8-5 μm, and the superconducting carbon black is acetylene carbon black, and the particle diameter is 30-45nm; the monofilament diameter of the carbon fiber 5μm, the aspect ratio is 2-15:1; the particle size of silicon carbide is 1.3-1.5μm;

Slowly cool the mixed slurry to room temperature, and then vacuum freeze-dry to obtain a freeze-dried product; after grinding, use a 200-mesh screen to sieve the ground product 4 times to obtain conductive micropowder for polymer-based PTC materials, with an average particle size of The diameter is 24 μm.

Comparative example 2

The preparation method of the conductive micropowder of this comparative example comprises the following steps:

1) Weigh 300g of thermoplastic polyurethane elastomer rubber (TPU), 30g of sodium dodecylsulfonate, 20g of OP-10, and 30g of glyceryl caprylate and place it in a reaction kettle, heat up to 80°C to completely melt the TPU, and Stir evenly; the melting point of the TPU used is 60°C;

Take 500mL of deionized water at 85°C and slowly add it into the reaction kettle maintained at 115°C, then pressurize the reaction kettle to 3-6MPa, and then disperse at 115°C at a speed of 600r/min for 0.5h at a high speed to completely emulsify the TPU;

2) Continue to maintain the reaction temperature at 85°C, add 150g of graphene-based two-dimensional carbon material, 80g of superconducting carbon black, 50g of carbon fiber, and 110g of silicon carbide into the reactor, and then continue to disperse at 85°C for 1 hour and mix well , to obtain a mixed slurry; the graphene-like two-dimensional carbon material is multilayer graphene, with a sheet diameter of 5-8 μm, and the superconducting carbon black is acetylene carbon black, with a particle diameter of 30-45 nm; the single filament diameter of the carbon fiber is 6.5 μm, and the length The diameter ratio is 2-15:1; the particle size of silicon carbide is 1.3-1.5μm;

Slowly cool the mixed slurry to room temperature, and then vacuum freeze-dry to obtain a freeze-dried product; after grinding, use a 200-mesh screen to sieve the ground product 4 times to obtain conductive micropowder for polymer-based PTC materials, with an average particle size of The diameter is 28μm;

Comparative example 3

The only difference between the PCT self-temperature-controlling paint in this comparative example and the PTC self-temperature-controlling paint in Example 14 is that the conductive fine powder used in this comparative example is the conductive fine powder prepared in Comparative Example 1.

Comparative example 4

The difference between the PCT self-temperature-controlling coating of this comparative example and the PTC self-temperature-controlling coating of Example 13 is only that: the conductive micropowder adopted in this comparative example is replaced by graphene-like two-dimensional carbon material, superconducting carbon black, carbon fiber and nitrogen The filler composed of aluminum oxide, the mass ratio of graphene-like two-dimensional carbon material, superconducting carbon black, carbon fiber and aluminum nitride is 150:100:30:100; the graphene-like two-dimensional carbon material, superconducting Carbon black, carbon fiber and aluminum nitride are the same as in Example 7.

Comparative example 5

The only difference between the PCT self-temperature-controlling paint in this comparative example and the PTC self-temperature-controlling paint in Example 17 is that the conductive fine powder used in this comparative example is the conductive fine powder prepared in Comparative Example 2.

Experimental example 1

The specifications of the PTC self-temperature-controlling coatings of Examples 13 to 15 and Comparative Examples 1 to 2 are made by screen printing respectively, and the length * width * thickness is an electrothermal film of 115mm * 45.75mm * 30 μm, on both sides (115mm ×30μm surface) was coated with conductive silver paste, and subjected to a temperature resistance test at room temperature -110°C and multiple power-on tests, and the relevant data were obtained as shown in Figure 1 and Table 1.

Table 1 Test results of resistance temperature test and multiple power-on tests

Experimental example 2

The PTC self-temperature-controlling coatings of Examples 16-18 and Comparative Examples 2-3 were made into an electrothermal film with specifications of length × width × thickness 115mm × 45.75mm × 30 μm by screen printing, and the two sides (115mm × 30μm surface) was coated with conductive silver paste, and subjected to a temperature resistance test at room temperature -70°C and multiple power-on tests, and the relevant data were obtained as shown in Figure 2 and Table 2.

Table 2 Test results of temperature resistance test and multiple power-on tests

Claims (19)

1. A conductive micropowder for polymer-based PTC material, characterized in that: comprise a polymer-based PTC material solid filler and a crystalline organic layer coated on the polymer-based PTC material solid filler surface; The solid filler for the polymer-based PTC material includes a conductive carbon material; the main component of the crystalline organic layer is a crystalline organic material, and the mass ratio of the conductive carbon material to the crystalline organic material is 10-120:10-50; The particle size of the conductive fine powder is ≤80μm. 2. The conductive micropowder for polymer-based PTC materials according to claim 1, characterized in that: the melting point of the crystalline organic matter is T, 40°C≤T<80°C or T≥80°C; 40°C≤ When T<80°C, the crystalline organic matter is a crystalline polymer and/or non-polymer crystalline organic matter; when T≥80°C, the crystalline organic matter is a crystalline polymer. 3. The conductive micropowder for polymer-based PTC materials according to claim 2, characterized in that: 40°C≤T<80°C, the crystalline polymer is polyethylene glycol, ethylene-vinyl acetate copolymer, One or any combination of 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 80°C≤T≤120°C, the crystalline polymer is polyethylene, polyethylene wax, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-acrylic acid copolymer, polyethylene oxide, One or any combination of polyvinyl chloride and chlorinated polyethylene. 4. the conductive micropowder for polymer base PTC material according to claim 1, is characterized in that: described conductive carbon material is graphene class two-dimensional carbon material, superconducting carbon black and carbon fiber; Graphene class two-dimensional carbon material The mass ratio of carbon material, superconducting carbon black, carbon fiber and crystalline organic matter is 5-30:5-40:0-50:10-50; the sheet diameter of the graphene-like two-dimensional carbon material is 300nm-15μm The particle size of the superconducting carbon black is 35-300nm; the monofilament diameter of the carbon fiber is 1-10μm, and the aspect ratio is 2-15:1; the average particle size of the conductive micropowder is 10-30μm. 5. the conductive micropowder for polymer-based PTC material according to claim 4, characterized in that: said graphene-like two-dimensional carbon material is one of single-layer graphene, multilayer graphene, graphene oxide One or any combination; the superconducting carbon black is acetylene black and/or Ketjen black. 6. The conductive micropowder for polymer-based PTC material according to any one of claims 1 to 4, characterized in that: the solid filler for the polymer-based PTC material also includes an inorganic heat-conducting filler; the inorganic heat-conducting filler and The mass ratio of crystalline organic matter is 5-30:10-50. 7. A preparation method for conductive micropowder of polymer-based PTC material, characterized in that: comprising the steps of: drying the mixed slurry into solid, and then breaking into micropowder; The mixed slurry is obtained by dispersing the solid filler for the polymer-based PTC material in the crystalline organic emulsion; the solid filler for the polymer-based PTC material includes a conductive carbon material; the conductive carbon material and the crystalline organic emulsion The mass ratio of the crystalline organic matter is 10-120:10-50; the particle diameter of the conductive fine powder is ≤80 μm. 8. The method for preparing conductive micropowder for polymer-based PTC materials according to claim 7, characterized in that: the melting point of the crystalline organic matter is T, 40°C≤T<80°C or T≥80°C; When 40°C≤T<80°C, the crystalline organic matter is a crystalline polymer and/or non-polymer crystalline organic matter; when T≥80°C, the crystalline organic matter is a crystalline polymer. 9. The method for preparing conductive micropowder for polymer-based PTC materials according to claim 8, characterized in that: 40°C≤T<80°C, the crystalline polymer is polyethylene glycol, ethylene-vinyl acetate One or any combination of copolymer, oxidized polyethylene wax, and polycaprolactone, and the non-polymer crystalline organic compound is one or any combination of palmitic acid, lauric acid, and 12-hydroxystearic acid; or 80°C≤T≤120°C, the crystalline polymer is polyethylene, polyethylene wax, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-acrylic acid copolymer, polyethylene oxide, One or any combination of polyvinyl chloride and chlorinated polyethylene. 10. the preparation method of the conductive micropowder that is used for polymer base PTC material according to claim 7, is characterized in that: described conductive carbon material is made up of the component of following parts by weight: graphene class two-dimensional carbon material 5 ～30 parts, 5～40 parts of superconducting carbon black, 0～50 parts of carbon fiber; the mass ratio of the graphene-based two-dimensional carbon material to the crystalline organic matter is 5～30:10～50; the graphene-based The sheet diameter of the two-dimensional carbon material is 300nm-15μm; the particle size of the superconducting carbon black is 30-300nm; the monofilament diameter of the carbon fiber is 1-10μm, and the aspect ratio is 2-15:1; the conductive The average particle diameter of the fine powder is 10-30 μm. 11. the preparation method of the conductive micropowder that is used for polymer base PTC material according to claim 10, is characterized in that: described superconducting carbon black is acetylene carbon black and/or ketjen black; The dimensional carbon material is one or any combination of single-layer graphene, multi-layer graphene, and graphene oxide. 12. the preparation method of the conductive micropowder that is used for polymer base PTC material according to claim 7, is characterized in that: described crystalline organic matter emulsion is that crystalline organic matter is dispersed in water and forms; The crystalline organic matter emulsion The preparation method comprises the following steps: heating the crystalline organic matter, emulsifier and dispersant to above the melting point of the crystalline organic matter, melting and mixing, and then adding water to disperse and emulsify at a set pressure and set temperature to obtain; The boiling point under constant pressure is not lower than the melting point of crystalline organic matter, and the set temperature is not higher than the boiling point of water under the set pressure. 13. the preparation method of the conductive micropowder that is used for polymer base PTC material according to claim 12, is characterized in that: described emulsifying agent is anionic emulsifying agent and/or nonionic emulsifying agent; Described anionic emulsifying agent The agent is one or any combination of alkyl sulfate, alkyl sulfonate, alkylbenzene sulfonate; the nonionic emulsifier is alkylphenol polyoxyethylene ether emulsifier, sorbitan fat One or any combination of ester emulsifiers, polyoxyethylene sorbitan fatty acid ester emulsifiers; the dispersant is one of fatty acid dispersants, aliphatic amide dispersants, and glyceride dispersants species or any combination. 14. the preparation method of the conductive micropowder that is used for polymer-based PTC material according to claim 7, is characterized in that: described polymer-based PTC material solid filler also comprises inorganic heat-conducting filler, and described inorganic heat-conducting filler and crystallization The mass ratio of the crystalline organic matter in the latex organic matter emulsion is 5-30:10-50; the particle diameter of the inorganic heat-conducting filler is 50 nm-5 μm. 15. the preparation method of the conductive micropowder that is used for polymer-based PTC material according to claim 14, is characterized in that: described inorganic heat-conducting filler is selected from silicon carbide, silicon dioxide, boron nitride, aluminum nitride One or any combination. 16. A PTC self-temperature-controlling coating, characterized in that: it includes resin emulsion and conductive micropowder and additives dispersed in the resin emulsion; Conductive micropowder of PTC-based materials or conductive micropowder for polymer-based PTC materials prepared by the preparation method according to any one of claims 7-15. 17. The PTC self-temperature-controlling paint according to claim 16, characterized in that: the mass ratio of the solid matter in the resin emulsion to the crystalline organic matter in the conductive fine powder is 30-60:10-50. 18. The PTC self-temperature control coating according to claim 16, characterized in that: the resin emulsion is one or any combination of polyurethane emulsion, acrylic emulsion, acrylate emulsion, silicone emulsion, epoxy resin emulsion; The solid content of the resin emulsion is 30-60%. 19. The PTC self-temperature control coating according to claim 16, characterized in that: the additives include defoamers and leveling agents; the mass ratio of the defoamers, leveling agents and resin emulsions is 3 to 50 :3～50:1000; the defoamer is a silicone type defoamer and/or polyether modified silicone type defoamer; the leveling agent is an acrylic leveling agent, an acrylic leveling agent One or any combination of agent, silicone leveling agent.

Images