A fluorine-silicon rubber-plastic alloy-based PTC material and preparation method thereof

Abstract

The present invention discloses a fluorosilicone rubber-plastic alloy-based PTC material, which comprises, by weight: 75-90 parts of fluoroplastics, 10-25 parts of silicone rubber, 15-30 parts of conductive powder, 5-15 parts of compatibilizer, 5-15 parts of zinc oxide, 1-3 parts of calcium carbonate, 0.1-1 parts of coupling agent, 0.25-1.25 parts of cerium oxide, and 0.2-0.5 parts of cross-linking agent. Compared with the prior art, the beneficial effect of the present invention is that the heating belt prepared by using the PTC material of the present invention has excellent performance in terms of maximum maintenance temperature, maximum bearing temperature, PTC strength, room temperature resistivity, tensile strength, elongation at break, thermal stability, etc., and meets the performance requirements of ultra-high temperature (200°C) heating belt products.

Description

Technical Field

[0001] The invention relates to the technical field of chemical engineering, and in particular to a fluorosilicone rubber-plastic alloy-based PTC material and a preparation method thereof. Background Art

[0002] In recent years, with the increasing scarcity of global energy resources and the increasingly prominent environmental pollution problem, the replacement of traditional energy resource consumption with electric energy has become the mainstream today. In the field of heating industry, electric heating has gradually replaced traditional steam, coal and hot water heating forms and become the first choice for heating and heat preservation.

[0003] Generally speaking, self-controlling temperature electric heating cables can be divided into low temperature, medium temperature, high temperature and ultra-high temperature series according to the temperature level, and the technical difficulty becomes greater with the increase of temperature level. There is relatively little research on products with temperature levels above high temperature, and there is a lack of ultra-high temperature (200℃) heating cable products with stable performance. Summary of the invention

[0004] In order to solve the problems mentioned in the above background technology, the present invention provides a fluorosilicone rubber-plastic alloy-based PTC material and a preparation method thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The first aspect of the present invention provides a fluorosilicone rubber-plastic alloy-based PTC material, which includes, by mass, 75-90 parts of fluoroplastic, 10-25 parts of silicone rubber, 15-30 parts of conductive powder, 5-15 parts of compatibilizer, 5-15 parts of zinc oxide, 1-3 parts of calcium carbonate, 0.1-1 parts of coupling agent, 0.25-1.25 parts of cerium oxide, and 0.2-0.5 parts of cross-linking agent.

[0007] Preferably, the preparation method of the conductive powder is as follows:

[0008] Carbon black powder and graphite powder are dispersed in an ethanol aqueous solution, stirred and heated, 3,3,3-trifluoropropyltrimethoxysilane is added, heated and stirred for reaction, dried, cooled, Tris (trishydroxymethylaminomethane) and dopamine are added, the pH of the system is adjusted to 8.5, stirred for reaction, washed with water, washed with ethanol, and dried to obtain a conductive powder.

[0009] Preferably, the preparation method of the compatibilizer is as follows:

[0010] Under nitrogen protection, 1,3,5-trimethyl-1,3,5-tri(3,3,3-trifluoropropyl)cyclotrisiloxane and tetrabutylammonium hydroxide are uniformly mixed and heated for reaction to obtain a catalyst;

[0011] Under nitrogen protection, 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane and a catalyst are uniformly mixed, heated for reaction, and deionized water is added for end-capping to obtain hydroxyl-terminated polyfluorosilicone, i.e., a compatibilizer.

[0012] Preferably, the mass ratio of the carbon black powder, graphite powder, 3,3,3-trifluoropropyltrimethoxysilane, Tris (trishydroxymethylaminomethane), and dopamine is 100: (10-20): (5-15): (10-30): (80-120).

[0013] Preferably, the mass concentration of the ethanol aqueous solution is 60-80%.

[0014] Preferably, the mass ratio of the 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane to tetrabutylammonium hydroxide is 100:(5-15).

[0015] Preferably, the mass ratio of the 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane, the catalyst and deionized water is 100:(5-15):(1-3).

[0016] Preferably, the fluoroplastic is a copolymer of perfluorovinyl ether and tetrafluoroethylene, and the silicone rubber is methyl vinyl silicone rubber.

[0017] Preferably, the coupling agent is isopropyl tri(dioctyl pyrophosphate) titanate, and the crosslinking agent is di-tetra-sulfurizer.

[0018] The second part of the present invention provides a method for preparing the above-mentioned PTC material, wherein fluoroplastic, silicone rubber, conductive powder, compatibilizer, zinc oxide, calcium carbonate, coupling agent, cerium oxide, and crosslinking agent are premixed, melt-mixed, and extruded and granulated to obtain the PTC material.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The heating tape prepared using the PTC material of the present invention has excellent performance in terms of maximum maintenance temperature, maximum withstand temperature, PTC strength, room temperature resistivity, tensile strength, elongation at break, thermal stability, etc., meeting the performance requirements of ultra-high temperature (200°C) heating tape products.

[0021] 2. The present invention modifies the surface of carbon black powder and graphite powder by using a fluorine-containing silane coupling agent (3,3,3-trifluoropropyltrimethoxysilane), and then polymerizes dopamine on the surface of the modified powder to obtain a modified powder coated with polydopamine. There are a large number of hydroxyl groups on the polydopamine, which can form hydrogen bonds with carbon black and graphite to form polydopamine with a cross-linked network structure, thereby achieving uniform coating on the surface of the modified powder.

[0022] 3. The compatibilizer of the present invention is prepared by ring-opening polymerization of 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane, and end-capping with the addition of deionized water to obtain hydroxyl-terminated polyfluorosilicone. Under the action of the compatibilizer, when the conductive powder (modified powder coated with polydopamine) is melt-mixed with fluoroplastics and silicone rubber, the deformation of the fluorosilicone rubber-plastic alloy molecular chain can be suppressed under the action of hydrogen bonds, van der Waals forces, etc., thereby achieving a better dispersion effect and improving the performance of the PTC material. DETAILED DESCRIPTION

[0023] Unless otherwise specified, the raw materials and reagents used in the present invention are commercially available or can be prepared by known methods.

[0024] Some of the raw materials come from the following sources:

[0025] Fluoroplastic: Chemours PFA-345;

[0026] Silicone rubber: Wacker R401 / 40;

[0027] Carbon black powder: ENSACO-260G;

[0028] Graphite powder: Dongkai graphite 1000 mesh;

[0029] Cross-linking agent: AkzoNobel, di-tetra-vulcanizing agent.

[0030] Preparation Example 1

[0031] Disperse 100g of carbon black powder and 15g of graphite powder in 2L of 70% ethanol aqueous solution, stir and heat to 50°C, add 10g of 3,3,3-trifluoropropyltrimethoxysilane, stir and react at 60°C for 2h, dry, cool to 25°C, add 20g of Tris (trishydroxymethylaminomethane) and 100g of dopamine, adjust the pH of the system to 8.5, stir and react at 40°C for 10h, wash with water, wash with ethanol, and dry to obtain a conductive powder.

[0032] Preparation Example 2

[0033] The difference between this preparation example and preparation example 1 is that:

[0034] Disperse 100g of carbon black powder and 10g of graphite powder in 2L of 70% ethanol aqueous solution;

[0035] The rest is exactly the same as Preparation Example 1.

[0036] Preparation Example 3

[0037] The difference between this preparation example and preparation example 1 is that:

[0038] Disperse 100g of carbon black powder and 20g of graphite powder in 2L of 70% ethanol aqueous solution;

[0039] The rest is exactly the same as Preparation Example 1.

[0040] Preparation Example 4

[0041] The difference between this preparation example and preparation example 1 is that:

[0042] Disperse 100g of carbon black powder and 0g of graphite powder in 2L of 70% ethanol aqueous solution;

[0043] The rest is exactly the same as Preparation Example 1.

[0044] Preparation Example 5

[0045] The difference between this preparation example and preparation example 1 is that:

[0046] Disperse 100g of carbon black powder and 30g of graphite powder in 2L of 70% ethanol aqueous solution;

[0047] The rest is exactly the same as Preparation Example 1.

[0048] Preparation Example 6

[0049] Under nitrogen protection, 10 g of 1,3,5-trimethyl-1,3,5-tri(3,3,3-trifluoropropyl)cyclotrisiloxane and 1 g of tetrabutylammonium hydroxide were mixed evenly, heated to 75° C. and reacted for 2 h to obtain a catalyst.

[0050] Under nitrogen protection, 100 g of 1,3,5-trimethyl-1,3,5-tri(3,3,3-trifluoropropyl)cyclotrisiloxane and 10 g of catalyst were mixed evenly, reacted at 70 ° C for 1 h, heated to 90 ° C for 2 h, and then 2 g of deionized water was added for end-capping. The mixture was stirred and heated to 160 ° C and reacted for 1 h to obtain hydroxyl-terminated polyfluorosilicone, i.e., a compatibilizer. Example 1

[0051] A method for preparing a fluorosilicone rubber-plastic alloy-based PTC material comprises the following steps: premixing 80 parts of fluoroplastic, 15 parts of silicone rubber, 20 parts of conductive powder (Preparation Example 1), 10 parts of a compatibilizer (Preparation Example 6), 10 parts of zinc oxide, 2 parts of calcium carbonate, 0.5 parts of a coupling agent, 0.75 parts of cerium oxide, and 0.35 parts of a crosslinking agent, and melt-kneading the premixed materials at 310-330° C. for 10-30 minutes, and extruding and granulating to obtain the PTC material. Example 2

[0052] The difference between this embodiment and embodiment 1 is that:

[0053] 15 parts of conductive powder (Preparation Example 1);

[0054] The rest is exactly the same as in Example 1. Example 3

[0055] The difference between this embodiment and embodiment 1 is that:

[0056] 30 parts of conductive powder (Preparation Example 1);

[0057] The rest is exactly the same as in Example 1. Example 4

[0058] The difference between this embodiment and embodiment 1 is that:

[0059] 20 parts of conductive powder (Preparation Example 2);

[0060] The rest is exactly the same as in Example 1. Example 5

[0061] The difference between this embodiment and embodiment 1 is that:

[0062] 20 parts of conductive powder (Preparation Example 3);

[0063] The rest is exactly the same as in Example 1.

[0064] Comparative Example 1

[0065] The difference between this comparative example and Example 1 is that:

[0066] 20 parts of conductive powder (Preparation Example 4);

[0067] The rest is exactly the same as in Example 1.

[0068] Comparative Example 2

[0069] The difference between this comparative example and Example 1 is that:

[0070] 20 parts of conductive powder (Preparation Example 5);

[0071] The rest is exactly the same as in Example 1.

[0072] Comparative Example 3

[0073] The difference between this comparative example and Example 1 is that:

[0074] Compatibilizer 0 parts;

[0075] The rest is exactly the same as in Example 1.

[0076] Results and Testing

[0077] The PTC materials prepared in Examples 1-5 and Comparative Examples 1-3 were co-extruded with two parallel nickel-plated copper wires to obtain corresponding PTC heating cables, which were subjected to mechanical and electrical tests. The results are shown in Table 1.

[0078] Among them, the thermal stability is based on the standard requirements of IEC60079-30-1. Long-term hot and cold cycles (1500 times, 750 hours) are performed at room temperature and maximum operating temperature, and the thermal stability of the product is evaluated by the power retention rate before and after the cycle.

[0079] Table 1

[0080]

[0081] From Table 1 and Examples 1-5, it can be seen that the heating tape prepared using the PTC material of the present invention has excellent performance in terms of maximum maintenance temperature, maximum tolerance temperature, PTC strength, room temperature resistivity, tensile strength, elongation at break, thermal stability, etc.

[0082] By comparing Example 1 and Comparative Examples 1 and 2, it can be seen that carbon black powder and graphite powder have a very important influence on the performance of the PTC material. When no graphite powder is added (Comparative Example 1) or excessive graphite powder is added (Comparative Example 2), the PTC strength, room temperature resistivity, tensile strength, elongation at break and thermal stability of the material are significantly reduced. However, when the two are used at the same time (within a specific range), the performance of the PTC material is significantly improved, with a synergistic enhancement effect.

[0083] By comparing Example 1 and Comparative Example 3, it can be seen that whether to add a compatibilizer also has a very important influence on the performance of the PTC material. Without adding a compatibilizer, the PTC strength, room temperature resistivity, tensile strength, elongation at break and thermal stability of the material are significantly reduced.

[0084] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A fluorosilicone rubber-plastic alloy-based PTC material, characterized in that: Calculated by mass, it includes: 75-90 parts of fluoroplastics, 10-25 parts of silicone rubber, 15-30 parts of conductive powder, 5-15 parts of compatibilizer, 5-15 parts of zinc oxide, 1-3 parts of calcium carbonate, 0.1-1 parts of coupling agent, 0.25-1.25 parts of cerium oxide, and 0.2-0.5 parts of cross-linking agent; The preparation method of the conductive powder is as follows: Disperse carbon black powder and graphite powder in an ethanol aqueous solution, stir and heat, add 3,3,3-trifluoropropyltrimethoxysilane, heat and stir to react, dry, cool, add Tris (trishydroxymethylaminomethane) and dopamine, adjust the pH of the system to 8.5, stir to react, wash with water, wash with ethanol, and dry to obtain a conductive powder; The preparation method of the compatibilizer is as follows: Under nitrogen protection, 1,3,5-trimethyl-1,3,5-tri(3,3,3-trifluoropropyl)cyclotrisiloxane and tetrabutylammonium hydroxide are uniformly mixed and heated for reaction to obtain a catalyst; Under nitrogen protection, 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane and a catalyst are uniformly mixed, heated for reaction, and deionized water is added for end-capping to obtain hydroxyl-terminated polyfluorosilicone, i.e., a compatibilizer; The mass ratio of the carbon black powder, graphite powder, 3,3,3-trifluoropropyltrimethoxysilane, Tris (trishydroxymethylaminomethane), and dopamine is 100: (10-20): (5-15): (10-30): (80-120).

2. A fluorosilicone rubber-plastic alloy-based PTC material according to claim 1, characterized in that: The mass concentration of the ethanol aqueous solution is 60-80%.

3. A fluorosilicone rubber-plastic alloy-based PTC material according to claim 1, characterized in that: The mass ratio of the 1,3,5-trimethyl-1,3,5-tri(3,3,3-trifluoropropyl)cyclotrisiloxane to tetrabutylammonium hydroxide is 100:(5-15).

4. A fluorosilicone rubber-plastic alloy-based PTC material according to claim 1, characterized in that: The mass ratio of the 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane, the catalyst and deionized water is 100:(5-15):(1-3).

5. A fluorosilicone rubber-plastic alloy-based PTC material according to claim 1, characterized in that: The fluoroplastic is a copolymer of perfluorovinyl ether and tetrafluoroethylene, and the silicone rubber is methyl vinyl silicone rubber.

6. A fluorosilicone rubber-plastic alloy-based PTC material according to claim 1, characterized in that: The coupling agent is isopropyl tri(dioctyl pyrophosphate acyloxy) titanate, and the crosslinking agent is di-tetra-sulfurizer.

7. A method for preparing the PTC material according to any one of claims 1 to 6, characterized in that: Fluoroplastic, silicone rubber, conductive powder, compatibilizer, zinc oxide, calcium carbonate, coupling agent, cerium oxide and cross-linking agent are premixed, melt-kneaded, extruded and granulated to obtain the PTC material.

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