Fluorine-containing polymer with high thermal conductivity and preparation method thereof

Abstract

The invention relates to the technical field of fluorine-containing polymers, in particular to a high-thermal-conductivity fluorine-containing polymer and a preparation method thereof.The high-thermal-conductivity fluorine-containing polymer is prepared from, by weight, 100 parts of fluororubber, 10-50 parts of thermal conductive filler and 1-6 parts of cross-linking agent; the fluororubber is a fluorine-containing polymer with the fluorine content larger than or equal to 50 wt%. The heat-conducting property and the heat stability of the fluorine-containing polymer can be improved, the tensile strength of the fluorine-containing polymer can be improved, the heat-conducting property and the mechanical property are synergistically improved, and the fluorine-containing polymer can be applied to a high-temperature use environment and an application scene requiring high heat dissipation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fluoropolymers, in particular to a high-thermal-conductivity fluoropolymer and a preparation method thereof. BACKGROUND

[0002] Fluororubber (FKM) is widely used in sealing, insulation and protective materials in extreme environments due to its excellent high-temperature resistance (-40℃ to 300℃), chemical corrosion resistance (oil, acid, solvent) and mechanical stability. However, traditional fluororubber is prone to heat accumulation in scenarios requiring rapid heat dissipation, resulting in material aging and other problems.

[0003] For example, Chinese patent application CN101875750A discloses a low-compression-permanent-deformation fluororubber compound and a preparation method thereof. The fluororubber compound is prepared by mixing binary fluororubber, ternary fluororubber, active magnesium oxide, ultra-fine calcium hydroxide, benzyl triphenyl phosphonium chloride, reinforcing agent, inorganic filler, release agent, vulcanizing agent and plasticizer. The preparation process includes mixing, mixing and re-mixing steps. The prepared fluororubber has the advantages of low compression permanent deformation, but the rubber mixing process is too complex, and the cost of mixing two rubbers is high, which is not suitable for industrial application. Chinese patent application CN105086294A chemically bonds modified graphene with fluororubber and ternary ethylene-propylene rubber, which can uniformly disperse the modified graphene in the rubber, thereby improving the thermal conductivity of the fluororubber. However, the heat resistance and other abilities of the fluororubber itself are reduced. SUMMARY

[0004] To solve the problems in the prior art, the present application provides a high-thermal-conductivity fluoropolymer. The preparation raw materials include, by weight fraction, 100 parts of fluororubber, 10-50 parts of thermal conductive filler and 1-6 parts of crosslinking agent. The fluororubber is a fluorine-containing polymer with a fluorine content of ≥50wt%.

[0005] In one embodiment, the preparation raw materials include, by weight fraction, 100 parts of fluororubber, 20-40 parts of thermal conductive filler and 2-4 parts of crosslinking agent.

[0006] In the present application, the fluorine content in the fluororubber is limited to ≥50wt%. On the one hand, fluorine atoms form a dense "fluorine shielding layer" in the molecular chain, which enhances the van der Waals force between the molecular chains, hinders the movement of the chain segments, and makes the structure more regular, thereby improving the thermal conductivity efficiency and the thermal stability of the chemical structure of the polymer matrix. On the other hand, the C-F bond in the high-fluorine-content polymer has strong electronegativity, which forms directional attraction with the polar sites on the surface of the thermal conductive filler, reducing the agglomeration of the filler. At the same time, the melt viscosity of the high-fluorine-content polymer is moderate, avoiding the sedimentation of the filler, and facilitating the formation of a three-dimensional network heat dissipation network.

[0007] In an embodiment, the fluororubber is selected from one or more of a vinylidene fluoride-hexafluoropropylene copolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, a vinylidene fluoride-tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, a vinylidene fluoride-trifluorochloroethylene, a tetrafluoroethylene-propylene copolymer, an ethylene-tetrafluoroethylene-perfluoroalkyl vinyl ether, a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer.

[0008] In an embodiment, the thermally conductive filler is a non-oxidized inorganic filler.

[0009] In an embodiment, the non-oxidized inorganic filler is a nitride inorganic filler.

[0010] In an embodiment, the nitride inorganic filler comprises boron nitride.

[0011] In an embodiment, the boron nitride is hexagonal boron nitride.

[0012] In an embodiment, the hexagonal boron nitride is flaky hexagonal boron nitride with an average particle size D50 of 10-30 μm.

[0013] In the present application, boron nitride is selected as the non-oxidized inorganic filler. On the one hand, the non-oxidized inorganic filler contains strong atomic bonds which can effectively weaken the phonon scattering phenomenon caused by lattice defects, thereby having strong thermal conductivity. On the other hand, when the boron nitride is flaky hexagonal boron nitride, the layered morphology of h-BN can form a two-dimensional thermal conduction path of "face-to-face contact" in the polymer, superimposed with the one-dimensional path of the fluororubber crystalline region, to easily build a three-dimensional thermal conduction network and accelerate heat conduction.

[0014] In an embodiment, the crosslinking agent comprises a peroxide vulcanizing agent.

[0015] In an embodiment, the peroxide vulcanizing agent comprises any one of dicumyl peroxide, di-tert-butyl peroxide, benzoperozo, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0016] In an embodiment, the peroxide vulcanizing agent is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0017] In an embodiment, the crosslinking agent comprises any one of Fluorolink 5, 2,2-bis-(3-amino-4-hydroxyphenyl)-hexafluoropropane.

[0018] In an embodiment, the raw material for preparing the high-thermal-conductivity fluoropolymer further comprises a crosslinking aid triallyl isocyanurate.

[0019] The second aspect of the present application provides a preparation method of a high-thermal-conductivity fluorine-containing polymer, at least comprising: mixing fluorine rubber and thermal conductive filler after mixing, and mixing uniformly with crosslinking agent, and then performing twice vulcanization, to obtain the high-thermal-conductivity fluorine-containing polymer.

[0020] The conditions of the twice vulcanization are as follows: one-stage vulcanization: 160-180 DEG C, 10-30 min, 3-10 Mpa;

[0021] Two-stage vulcanization: 230-290 DEG C, 10 h, 3-10 Mpa.

[0022] Beneficial effects

[0023] 1. The present application adopts a fluorine-containing polymer with a fluorine content of 50 wt%, which improves the thermal conduction efficiency and the thermal stability of the chemical structure of the polymer matrix.

[0024] 2. The present application selects non-oxidizing inorganic fillers and fluorine-containing polymers, especially non-oxidizing inorganic fillers in the form of hexagonal boron nitride with a particle size of 10-30 μm, which can further improve the thermal conductivity and thermal stability of the fluorine-containing polymer, with a thermal conductivity of >0.2 W / (m·K) and a specific heat capacity of 1.34 J / (g·K).

[0025] 3. In the present application, 100 parts of fluorine rubber with a fluorine content of 50 wt%, 10-50 parts of nitride inorganic fillers, and 1-6 parts of crosslinking agent are used, which can improve the tensile strength of the fluorine-containing polymer to more than 9 MPa.

[0026] 4. The preparation method of the high-thermal-conductivity fluorine-containing polymer provided by the present application is simple, and the obtained fluorine-containing polymer has no obvious volatile matter when used at 230 DEG C for a long time, and can be completely applied in high-temperature use environment and high-heat-dissipation-demand application scenarios. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application. The experimental methods not specified in the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments not specified by the manufacturer are all conventional products that can be purchased on the market.

[0028] Example 1

[0029] The first aspect of the present embodiment provides a high-thermal-conductivity fluorine-containing polymer, and the preparation raw materials include: 100 parts of fluorine rubber, 20 parts of thermal conductive filler, and 2.5 parts of crosslinking agent.

[0030] The fluororubber is perfluoroether rubber, model PFR95HT, from Solvay.

[0031] The heat-conducting filler is powdered hexagonal boron nitride, with an average particle size D50 of 10 μm, from 3M.

[0032] The crosslinking agent is 2,5-dimethyl-2,5-di(tert-butyl peroxy)hexane.

[0033] The second aspect of the embodiment provides a preparation method of high-heat-conducting fluoropolymer, comprising: mixing fluororubber and heat-conducting filler to obtain a masterbatch;

[0034] Adding a crosslinking agent to the masterbatch, and performing twice vulcanization to obtain the high-heat-conducting fluoropolymer.

[0035] The conditions of the twice vulcanization are: one-stage vulcanization conditions: 170℃, 20min, 5Mpa; two-stage vulcanization conditions: 260℃, 10h, 5Mpa.

[0036] Example 2

[0037] The first aspect of the embodiment provides a high-heat-conducting fluoropolymer, and the preparation raw materials include, by weight fraction, 100 parts of fluororubber, 20 parts of heat-conducting filler, and 2.5 parts of crosslinking agent.

[0038] The fluororubber is perfluoroether rubber, model PFR95HT, from Solvay. The heat-conducting filler is flaky hexagonal boron nitride, with an average particle size D50 of 10 μm, from 3M.

[0039] The crosslinking agent is 2,5-dimethyl-2,5-di(tert-butyl peroxy)hexane.

[0040] The remaining embodiments are the same as those of Example 1.

[0041] Example 3

[0042] The first aspect of the embodiment provides a high-heat-conducting fluoropolymer, and the preparation raw materials include, by weight fraction, 100 parts of fluororubber, 20 parts of heat-conducting filler, and 2.5 parts of crosslinking agent.

[0043] The fluororubber is perfluoroether rubber, model PFR95HT, from Solvay. The heat-conducting filler is flaky hexagonal boron nitride, with an average particle size D50 of 20 μm, from 3M.

[0044] The crosslinking agent is 2,5-dimethyl-2,5-di(tert-butyl peroxy)hexane.

[0045] The remaining embodiments are the same as those of Example 1.

[0046] Example 4

[0047] The first aspect of the embodiment provides a high-thermal-conductivity fluoropolymer, and raw materials for preparation include, in terms of parts by weight, 100 parts of fluoroelastomer, 30 parts of thermal conductive filler, and 2.5 parts of crosslinking agent.

[0048] The fluoroelastomer is perfluoroether rubber, model PFR95HT, from Solvay.

[0049] The thermal conductive filler is flaky hexagonal boron nitride, with an average particle size D50 of 20 μm, from 3M.

[0050] The crosslinking agent is 2,5-dimethyl-2,5-di(tert-butyl peroxy) hexane.

[0051] The remaining embodiments are the same as those in Embodiment 1.

[0052] Embodiment 5

[0053] The first aspect of the embodiment provides a high-thermal-conductivity fluoropolymer, and raw materials for preparation include, in terms of parts by weight, 100 parts of fluoroelastomer, 40 parts of thermal conductive filler, and 2.5 parts of crosslinking agent.

[0054] The fluoroelastomer is perfluoroether rubber, model PFR95HT, from Solvay.

[0055] The thermal conductive filler is flaky hexagonal boron nitride, with an average particle size D50 of 20 μm, from 3M.

[0056] The crosslinking agent is 2,5-dimethyl-2,5-di(tert-butyl peroxy) hexane.

[0057] The remaining embodiments are the same as those in Embodiment 1.

[0058] Embodiment 6

[0059] The first aspect of the embodiment provides a high-thermal-conductivity fluoropolymer, and raw materials for preparation include, in terms of parts by weight, 100 parts of fluoroelastomer, 20 parts of thermal conductive filler, and 2.5 parts of crosslinking agent.

[0060] The fluoroelastomer is high-fluorine rubber, model Viton A-500, from Komocem (Shanghai) Co., Ltd.

[0061] The crosslinking agent is Fluorine Union No. 5, from Sanming Haisifeng Chemical Co., Ltd.

[0062] The thermal conductive filler is flaky hexagonal boron nitride, with an average particle size D50 of 20 μm, from 3M.

[0063] The remaining embodiments are the same as those in Embodiment 1.

[0064] Embodiment 7

[0065] The embodiment of the present application is identical to that of Example 1, except that the fluorine content of the fluororubber is 68wt%, and the model is GB600, from KUMHO CHEMICAL (SHANGHAI) CO., LTD.

[0066] The crosslinking agent is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0067] The raw material for preparing the high-thermal-conductivity fluoropolymer further includes a crosslinking aid TAIC (triallyl isocyanurate) 2 parts.

[0068] Example 8

[0069] The embodiment of the present application is identical to that of Example 1, except that the fluorine content of the fluororubber is 72.6wt%, and the model is G806, from ZHONGHAO CHENGLV CHEMICAL RESEARCH INSTITUTE CO., LTD.

[0070] The crosslinking agent is 2,2-bis-(3-amino-4-hydroxyphenyl)-hexafluoropropane.

[0071] Example 9

[0072] The embodiment of the present application is identical to that of Example 1, except that the fluorine content of the fluororubber is 72.5wt%, and the model is PFR1055B, from SINOCHINA.

[0073] The crosslinking agent is 2,2-bis-(3-amino-4-hydroxyphenyl)-hexafluoropropane.

[0074] Example 10

[0075] The embodiment of the present application is identical to that of Example 1, except that the fluorine content of the fluororubber is 53wt%, and the model is 400E, from AGC.

[0076] The crosslinking agent is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0077] The raw material for preparing the high-thermal-conductivity fluoropolymer further includes a crosslinking aid TAIC (triallyl isocyanurate) 2 parts.

[0078] Comparative Example 1

[0079] The first aspect of the present comparative example provides a fluoropolymer, and the raw material for preparing the fluoropolymer includes, in terms of parts by weight, 100 parts of fluororubber and 2.5 parts of crosslinking agent.

[0080] The fluororubber is perfluoroether rubber, and the model is PFR95HT, from SINOCHINA. The crosslinking agent is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0081] The remaining embodiments are the same as Example 1.

[0082] Comparative Example 2

[0083] The first aspect of the present comparative example provides a fluoropolymer, the raw materials for preparation include: 100 parts of fluoroelastomer, 20 parts of thermal conductive filler, 2.5 parts of crosslinking agent, by weight.

[0084] The fluoroelastomer is perfluoroether rubber, model PFR95HT, from Solvay. The thermal conductive filler is nano-amorphous boron nitride (a-BN), from Nippon Chemical Group.

[0085] The crosslinking agent is 2,5-dimethyl-2,5-di(tert-butyl peroxy) hexane.

[0086] The remaining embodiments are the same as Example 1.

[0087] Comparative Example 3

[0088] The first aspect of the present comparative example provides a fluoropolymer, the raw materials for preparation include: 100 parts of fluoroelastomer, 20 parts of thermal conductive filler, 2.5 parts of crosslinking agent, by weight.

[0089] The fluoroelastomer is perfluoroether rubber, model PFR95HT, from Solvay. The thermal conductive filler is wet mica, from BASF.

[0090] The crosslinking agent is 2,5-dimethyl-2,5-di(tert-butyl peroxy) hexane.

[0091] The remaining embodiments are the same as Example 1.

[0092] Comparative Example 4

[0093] The first aspect of the present comparative example provides a fluoropolymer, the raw materials for preparation include: 100 parts of fluoroelastomer, 20 parts of thermal conductive filler, 2.5 parts of crosslinking agent, by weight.

[0094] The fluoroelastomer is perfluoroether rubber, model PFR95HT, from Solvay.

[0095] The thermal conductive filler is a-silicon nitride, from Denka.

[0096] The crosslinking agent is 2,5-dimethyl-2,5-di(tert-butyl peroxy) hexane.

[0097] The remaining embodiments are the same as Example 1.

[0098] Comparative Example 5

[0099] The specific implementation of the comparative example is the same as example 1, except that the fluorine content of the fluorine-containing rubber (fluorosilicone rubber) is 28wt%, and the model is FSE 7360 from Mfg Hi-New Material Group.

[0100] Comparative example 6

[0101] The specific implementation of the comparative example is the same as example 1, except that the preparation raw materials include, by weight: 100 parts of silicone rubber, 20 parts of heat-conducting filler, and 2.5 parts of crosslinking agent.

[0102] The model of the silicone rubber is SR3250U from Shensin.

[0103] Performance test

[0104] 1. The samples prepared in examples 1-6 and comparative examples 1-4 were tested for thermal conductivity, specific heat capacity, tensile strength, and elongation at break, and the test results are shown in Table 1. The test standards are as follows:

[0105] Thermal conductivity: ASTM C177;

[0106] Specific heat capacity: ASTM E1269;

[0107] Tensile strength: ASTM D 412-Test Method B;

[0108] Elongation at break: ASTM D 412-Test Method B.

[0109] 2. The same mass and size samples prepared in examples 6-10 and comparative examples 5-6 were wrapped around a heating wire (300Ω / m), and the samples were connected to electricity for 10 hours at 230 degrees. It was observed that the samples of comparative examples 5-6 had a burnt smell, while the samples prepared in examples 6-10 were intact, indicating that the samples prepared in the examples of the present application have better heat resistance than the comparative examples.

[0110] Table 1

[0111]

[0112]

[0113] As can be seen from the test results in Table 1, the thermal conductivity of the fluorine-containing polymer prepared in examples 1-5 is >0.2 W / (m·K), the specific heat capacity is ≥1.34 J / (g·K), the tensile strength is greater than 9 MPa, and the elongation at break is up to 9.9%. The polymer can improve the heat-conducting effect while maintaining the mechanical properties of the material.

Claims

1. A high thermal conductivity fluorinated polymer, characterized in that: The raw materials for preparation include, by weight: 100 parts of fluororubber, 10-50 parts of thermal conductive filler, and 1-6 parts of crosslinking agent; the fluororubber is a fluorine-containing polymer with a fluorine content of ≥50wt%.

2. The high thermal conductivity fluorinated polymer according to claim 1, characterized in that Calculated by weight, the raw materials include: 100 parts of fluororubber, 20-40 parts of thermal conductive filler, and 2-4 parts of cross-linking agent.

3. The high thermal conductivity fluorinated polymer according to claim 2, characterized in that The fluororubber is selected from one or more of vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride-tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, vinylidene fluoride-chlorotrifluoroethylene, tetrafluoroethylene-propylene copolymer, ethylene-tetrafluoroethylene-perfluoroalkyl vinyl ether, and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer.

4. The high thermal conductivity fluorinated polymer according to claim 1, wherein The thermally conductive filler is a non-oxidizing inorganic filler.

5. The high thermal conductivity fluorinated polymer according to claim 4, characterized in that The non-oxidative inorganic filler is a nitride inorganic filler.

6. The high thermal conductivity fluorinated polymer according to claim 5, characterized in that The nitride-based inorganic filler includes boron nitride.

7. The high thermal conductivity fluorinated polymer according to claim 6, characterized in that The boron nitride is hexagonal boron nitride.

8. The high thermal conductivity fluorinated polymer according to claim 1, wherein The cross-linking agent includes a peroxide curing agent.

9. The high thermal conductivity fluorinated polymer according to claim 8, characterized in that The peroxide curing agent includes any one of dicumyl peroxide, di-tert-butyl peroxide, diphenylmethane peroxide, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

10. A method for preparing a high thermal conductivity fluorinated polymer according to any one of claims 1 to 9, characterized in that: At least: The fluororubber and the thermal conductive filler are kneaded and evenly mixed with the cross-linking agent, and then vulcanized twice to obtain the high thermal conductive fluorine-containing polymer.

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