阅读说明：本技术 一种高稳定性ptc材料 (High-stability PTC material ) 是由 袁建波 于 2021-08-05 设计创作，主要内容包括：本发明提供一种高稳定性PTC材料,由高分子基材、导电填料、以及内部反应生成盐构成；高分子基材占高稳定性PTC材料体积分数的40％～70％,导电填料占30％～60％；高分子基材由均匀分散的第一组分聚合物和第二组分聚合物构成；第二组分聚合物为阴离子离聚物,占所述高稳定性PTC材料体积分数的5％～10％；导电填料表面被阳离子聚合物修饰,均匀分散于所述聚合物基体之中；阴离子离聚物所含的对阳离子与阳离子聚合物的对阴离子形成内部反应生成盐。制成的PPTC电路保护元件具有更高的保持电流,以及更优的耐压耐流性能。制成的PPTC自限温发热膜具有更高的加热启动速率,长期使用加热速率衰减更低。(The invention provides a high-stability PTC material, which consists of a high-molecular base material, a conductive filler and an internal reaction generated salt; the polymer base material accounts for 40-70% of the volume fraction of the high-stability PTC material, and the conductive filler accounts for 30-60%; the polymer base material is composed of a first component polymer and a second component polymer which are uniformly dispersed; the second component polymer is an anionic ionomer and accounts for 5-10% of the volume fraction of the high-stability PTC material; the surface of the conductive filler is modified by cationic polymer and is uniformly dispersed in the polymer matrix; the counter cation contained in the anionic ionomer reacts internally with the counter anion of the cationic polymer to form a salt. The PPTC circuit protection element has higher holding current and better voltage and current resistance. The prepared PPTC self-temperature-limiting heating film has higher heating starting rate and lower heating rate attenuation after long-term use.)

1. A high-stability PTC material is characterized in that: the conductive filler is composed of a high molecular base material, a conductive filler and an internal reaction generated salt; the polymer base material accounts for 40-70% of the volume fraction of the high-stability PTC material, and the conductive filler accounts for 30-60% of the volume fraction of the high-stability PTC material; the polymer base material is composed of a first component polymer and a second component polymer which are uniformly dispersed; the second component polymer is an anionic ionomer, and the anionic ionomer accounts for 5-10% of the volume fraction of the high-stability PTC material; the surface of the conductive filler is modified by a cationic polymer and is uniformly dispersed in the polymer matrix; the cation pair contained in the anionic ionomer and the anion pair of the cationic polymer form an internal reaction to generate salt.

2. A high stability PTC material according to claim 1, wherein: the first component polymer comprises one of polyethylene, polypropylene, polyvinylidene fluoride, polyamide, polyester, polyphenyl ether, polyphenyl thioether, polyformaldehyde, phenolic resin, epoxy resin and polyhexafluoropropylene, and a copolymer and a mixture thereof.

3. A high stability PTC material according to claim 1, wherein: the anionic ionomer comprises one of sulfonic acid resin and acrylic resin; the cation pair contained in the anionic ionomer is one or the combination of zinc ion, magnesium ion and calcium ion.

4. A high stability PTC material according to claim 1, wherein: the conductive filler comprises one or the combination of cationic polymer modified metal particles, metal carbide particles, metal boride particles, carbon black, chopped carbon nanotubes and graphene.

5. A high stability PTC material according to claim 1, wherein: the cationic polymer is polyquaternary ammonium salt; the counter anion contained in the cationic ionomer is one or the combination of chloride ion and bromide ion.

6. A high stability PTC material according to claim 1, wherein: the preparation method of the conductive filler comprises the following steps: uniformly stirring the solvent, the cationic polymer, the coupling agent and the conductive particles, pumping the mixture into a sand mill, grinding and dispersing the mixture until the average particle size is less than 100 nanometers, and freeze-drying the mixture to obtain the conductive filler modified with the cationic polymer on the surface.

7. A high stability PTC material according to any one of claims 1 to 6, wherein: the processing method of the high-stability PTC material comprises the steps of adding the granules of the high-molecular base material and the conductive filler into an internal mixer for mixing, and molding a sheet by adopting an open mixing calendaring or extrusion mode.

8. A high stability PTC material according to any one of claims 1 to 6, wherein: taking the high-stability PTC material as a core layer, and compounding conductive metal foils on two surfaces to manufacture a PTC functional element; the conductive metal foil comprises one of copper foil, silver foil, nickel foil and nickel-plated copper foil, the conductive metal foil comprises a rough surface and a smoother surface, the rough surface is directly contacted with the high-stability PTC material core layer, and the smoother surface of the metal foil is respectively welded with the conductive part and connected in series in a protected circuit, so that the overcurrent and overtemperature protection effect is achieved.

9. A high stability PTC material according to any one of claims 1 to 6, wherein: the processing method of the high-stability PTC material comprises the steps of adding the granules of the high-molecular base material and the conductive filler into a solvent for dissolving and dispersing, coating the obtained dispersion liquid on the base material, and drying to obtain the high-stability PTC film material; the solvent comprises one or a mixed solvent of N-methylpyrrolidone, N-dimethylformamide and N, N-dimethylacetamide; the coating method comprises one of knife coating, roller coating and printing.

10. A high stability PTC material according to any one of claims 1 to 6, wherein: the high-stability PTC material is made into a film and compounded on a metal foil, the metal foil is etched into a finger electrode shape, a heat-conducting insulating glue layer is attached to two surfaces of the high-stability PTC material film attached with the finger electrode, and the finger electrode is used for leading out the electrical property and is used for a self-temperature-limiting heating element; the conductive metal foil comprises one of copper foil, nickel foil and nickel-plated copper foil, the conductive metal foil comprises a rough surface and a smoother surface, and the rough surface is in direct contact with the high-stability PTC material core layer.

Technical Field

The invention belongs to the technical field of new materials, and particularly relates to a high-stability PTC material.

Background

The polymer-based PTC composite material (PPTC) is prepared by taking a polymer as a matrix and conductive filler in the polymer as a raw material, wherein the content of the conductive filler exceeds a percolation threshold, a lower resistance value can be maintained at normal temperature, and when the temperature rises, the resistance change reaction in a specific temperature range is sharp and sharply rises. The element made of PPTC material is connected in series in an electronic circuit, a circuit can be kept at normal working temperature and rated current, the resistance is sharply increased under the over-temperature or high-current state to realize circuit shutdown, and the element can automatically recover the low-resistance state after fault removal, thereby playing the self-recovery protection role in the circuit. Based on the advantage of reusability of PPTC materials, the PPTC materials are widely applied to electronic circuits. The PPTC material can also be used as a self-temperature-limiting heating material, when a power supply is switched on, the PTC high polymer material in the PPTC material is heated to expand, the resistance is increased, the heating power is reduced, and the temperature is reduced; when the temperature is reduced, the PTC polymer material inside shrinks when cooled, the resistance is reduced, the heating power is increased, and the temperature is increased, so that the effect of automatically adjusting the temperature is achieved.

For PPTC circuit protection elements, a lower resistance value is required to enable stable power retention under rated operating current conditions, a higher voltage and current withstand capability under operating conditions, and a better recovery capability after repeated operation. Research shows that after repeated action of the traditional PPTC material, the defects of the interface between the polymer and the conductive particles caused by polymer expansion and contraction are important factors for increasing the resistance and deteriorating the voltage and current resistance. For a PPTC self-temperature-limiting heating device, a lower resistance value is also needed to obtain a larger starting heating power, and meanwhile, the starting power is reduced, the heating rate is attenuated, and the stable temperature drifts are caused by interface defects. Therefore, it is necessary to develop a high-stability PTC material.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the present invention provides a high-stability PTC material and a recoverable fuse, which are used to solve the problems of the PPTC protection element in the prior art such as voltage endurance and resistance stability in repeated operation.

In order to achieve the above objects and other related objects, the present invention provides a high stability PTC material, which comprises a polymer substrate, a conductive filler, and an internal reaction-generated salt; the polymer base material accounts for 40-70% of the volume fraction of the high-stability PTC material, and the conductive filler accounts for 30-60% of the volume fraction of the high-stability PTC material; the polymer base material is composed of a first component polymer and a second component polymer which are uniformly dispersed; the second component polymer is an anionic ionomer, and the anionic ionomer accounts for 5-10% of the volume fraction of the high-stability PTC material; the surface of the conductive filler is modified by a cationic polymer and is uniformly dispersed in the polymer matrix; the counter cation contained in the anionic ionomer reacts with the counter anion of the cationic polymer to form a salt in an internal reaction.

Optionally, the first component polymer comprises one of polyethylene, polypropylene, polyvinylidene fluoride, polyamide, polyester, polyphenylene oxide, polyphenylene sulfide, polyoxymethylene, phenolic resin, epoxy resin, polyhexafluoropropylene, and copolymers and mixtures thereof.

Optionally, the anionic ionomer comprises one of a sulfonic acid-based resin, an acrylic resin; the cation pair contained in the anionic ionomer is one or the combination of zinc ion, magnesium ion and calcium ion.

Optionally, the conductive filler comprises one or a combination of cationic polymer-modified metal particles, metal carbide particles, metal boride particles, carbon black, chopped carbon nanotubes, graphene.

Optionally, the cationic polymer is a polyquaternary ammonium salt; the counter anion contained in the cationic ionomer is one or the combination of chloride ion and bromide ion.

Optionally, the preparation method of the conductive filler comprises: uniformly stirring the solvent, the cationic polymer, the coupling agent and the conductive particles, pumping the mixture into a sand mill, grinding and dispersing the mixture until the average particle size is less than 100 nanometers, and freeze-drying the mixture to obtain the conductive filler modified with the cationic polymer on the surface.

Optionally, in the processing method of the high-stability PTC material, the granules of the polymer base material and the conductive filler are added into an internal mixer for mixing, and a sheet is formed by open mill calendering or extrusion.

Optionally, the high-stability PTC material is used as a core layer, and conductive metal foils are compounded on two surfaces of the core layer to manufacture a PTC functional element; the conductive metal foil comprises one of copper foil, silver foil, nickel foil and nickel-plated copper foil, the conductive metal foil comprises a rough surface and a smoother surface, the rough surface is directly contacted with the high-stability PTC material core layer, and the smoother surface of the metal foil is respectively welded with the conductive part and connected in series in a protected circuit, so that the overcurrent and overtemperature protection effect is achieved.

Optionally, in the processing method of the high-stability PTC material, the granules of the polymer substrate and the conductive filler are added into a solvent to be dissolved and dispersed, the obtained dispersion liquid is coated on the substrate, and the substrate is dried to obtain a high-stability PTC film; the solvent comprises one or a mixed solvent of N-methylpyrrolidone, N-dimethylformamide and N, N-dimethylacetamide; the coating method comprises one of knife coating, roller coating and printing.

Optionally, the high-stability PTC material is made into a thin film and compounded on a metal foil, the metal foil is etched into a finger electrode shape, a heat-conducting insulating glue layer is attached to two surfaces of the high-stability PTC material film attached with the finger electrode, and the finger electrode is used for leading out electrical property and is used for a self-temperature-limiting heating element; the conductive metal foil comprises one of copper foil, nickel foil and nickel-plated copper foil, the conductive metal foil comprises a rough surface and a smoother surface, and the rough surface is in direct contact with the high-stability PTC material core layer.

As described above, the high-stability PTC material of the present invention has the following advantageous effects: the cationic polymer attached to the conductive particles is connected with a large number of charges and hydrogen bonds in the anionic ionomer in the matrix, so that the generation of interface defects can be effectively reduced in the polymer expansion and contraction process of repeated action, a charge system formed by the cationic polymer and the anionic ionomer is favorable for reducing the matrix resistance, and lower volume resistance is obtained under the condition of the same volume fraction of the conductive particles. Meanwhile, uniformly dispersed divalent salt is generated in the material, so that the flame retardant effect is achieved, no flame retardant is required to be additionally added, and the material has higher compatibility in a matrix. The PPTC circuit protection element has higher holding current and better voltage and current resistance. The prepared PPTC self-temperature-limiting heating film has higher heating starting rate under rated voltage and lower heating rate attenuation after long-term use.

Drawings

Fig. 1 is a schematic structural diagram of a circuit protection device made of a high-stability PTC material according to the present invention. 1-a layer of PPTC material; 2-metal electrodes.

Fig. 2 is a schematic structural diagram of a self-temperature-limiting heating element made of a high-stability PTC material according to the present invention. A layer of 3-PPTC material; 4-metal interdigitated electrodes.

Detailed Description

The following description of the embodiments of the present invention is provided by way of specific examples, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

Example 1 (control sample):

PVDF and titanate coupling agent are added into an internal mixer, and tungsten carbide powder is added after 3-5 minutes, wherein the volume ratio of the PVDF to the titanate coupling agent to the tungsten carbide powder is 49: 1: 50%. Continuously banburying for 15 minutes, discharging, and calendering the obtained PPTC material by an open mill to obtain a sheet with the thickness of 0.30 mm. The sheet is placed between two layers of nickel-plated copper foils and tightly bonded together by a hot-pressing method. And finally, manufacturing the PPTC element A with the thickness of 4mm by 3mm through a punching process.

Example 2:

PVDF and Surlyn1650 (anion ionomer containing Zn ions) are added into an internal mixer, and after 3-5 minutes, the tungsten carbide powder modified by poly (diallyldimethylammonium chloride) is added, wherein the volume ratio of the PVDF to the Surlyn1650 to the anion ionomer containing Zn ions is 45 to 5 to 50 percent. Continuously banburying for 15 minutes, discharging, and calendering the obtained PPTC material by an open mill to obtain a sheet with the thickness of 0.30 mm. The sheet is placed between two layers of nickel-plated copper foils and tightly bonded together by a hot-pressing method. And finally, manufacturing the PPTC element B with the thickness of 4mm by 3mm through a punching process.

Example 3:

adding polyamide 1012 and calcium polyacrylate into an internal mixer, and adding poly (diallyldimethylammonium chloride) -modified titanium diboride powder after 3-5 minutes, wherein the volume ratio of the polyamide 1012 to the calcium polyacrylate is 35: 5: 60%. Continuously banburying for 15 minutes, discharging, and calendering the obtained PPTC material by an open mill to obtain a sheet with the thickness of 0.30 mm. The sheet was placed between two layers of copper foil and they were bonded tightly together by thermocompression bonding. And finally, manufacturing the PPTC element C with the thickness of 4mm by 3mm through a punching process.

Example 4:

adding polyethylene and magnesium polyacrylate into an internal mixer, and adding polydiallyl dimethyl ammonium bromide modified nickel powder after 3-5 minutes, wherein the volume ratio of the polyethylene to the magnesium polyacrylate is 60% to 10% to 40%. Continuously banburying for 15 minutes, discharging, and calendering the obtained PPTC material by an open mill to obtain a sheet with the thickness of 0.30 mm. The sheet was placed between two layers of nickel foil and they were bonded tightly together by hot pressing. And finally, manufacturing a PPTC element D with the thickness of 4mm by 3mm through a punching process.

Comparing the components A and B, it can be seen that compared with the traditional coupling agent combining polymer and filler, and under the same formula system, the high-stability PTC material of the invention has lower resistance, better pressure resistance and flow resistance, and better environmental stability. Even if the series D of the elements of the Ni powder system with lower resistance and more activity is adopted, the electronic and environmental stability of the series D of the elements is superior to that of the series A of the elements of the traditional metal carbide conductive filler, and the miniaturization of the PPTC recoverable fuse is started.

Example 5 (comparative sample):

and dissolving and dispersing PVDF and graphene powder in N-methyl pyrrolidone, roller-coating on a copper foil, drying, etching the copper foil into a finger electrode, attaching a heat-conducting insulating adhesive layer to two sides of the finger electrode, and leading the finger electrode out of electrical property to prepare the self-temperature-limiting heating element E. 220V start power 290W.

Example 6

Dissolving and dispersing PVDF, magnesium polyacrylate and polydiallyldimethylammonium chloride modified graphene powder in N-methylpyrrolidone, roller-coating on a copper foil, drying, etching the copper foil to form a finger electrode, attaching a heat-conducting insulating glue layer to two sides of the finger electrode, and leading the finger electrode out of electrical property to prepare the self-temperature-limiting heating element F. 220V starts power 230W.

The self-temperature-limited heating elements of the same size as in examples 5 and 6, element F using the high-stability PTC material of the present invention, had higher heat generation starting power.

In summary, the formulation of the high-stability PTC material of the present invention, the cationic polymer attached to the conductive particles has a large amount of charges and hydrogen bonds in the anionic ionomer in the matrix, which can effectively reduce the generation of interface defects during the polymer expansion and contraction process of repeated actions, and the charge system composed of the cationic polymer and the anionic ionomer is beneficial to reducing the matrix resistance, and lower bulk resistance can be obtained under the condition of the same volume fraction of conductive particles. The PPTC circuit protection element has higher holding current and better voltage and current resistance. The prepared PPTC self-temperature-limiting heating film has higher heating starting rate under rated voltage. Therefore, the present invention effectively overcomes the disadvantages of the prior art and has a high industrial value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.