Conductive fluororubber based on in-situ polymerization ionic liquid-polyurethane modification as well as preparation method and application of conductive fluororubber
By chemically bonding ionic liquids and polyurethane modifiers through in-situ polymerization, the problem of synergistic improvement of mechanical and electrical properties in the conductive modification of fluororubber was solved, and conductive fluororubber suitable for high-end functional devices was prepared.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 四川道弘新材料股份有限公司
- Filing Date
- 2026-03-30
- Publication Date
- 2026-05-12
AI Technical Summary
Existing fluororubber conductive modification technologies struggle to achieve excellent conductivity while maintaining mechanical properties. Furthermore, traditional methods suffer from problems such as filler agglomeration, poor interfacial compatibility, and uneven conductivity, failing to meet the requirements of high-end functional devices.
In situ polymerization of ionic liquid-polyurethane modifier is used to chemically bond the ionic liquid into the polyurethane molecular chain, and conductive fluororubber is prepared through in situ polymerization reaction to form a stable conductive network, improve interfacial compatibility and avoid filler agglomeration.
The conductive and mechanical properties of fluororubber have been synergistically improved, resulting in fluororubber with both high conductivity and excellent mechanical properties, which is suitable for aerospace, new energy vehicles, semiconductors and flexible wearable devices.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of chemical materials, specifically relating to a conductive fluororubber modified by in-situ polymerized ionic liquid-polyurethane, its preparation method, and its uses. Background Technology
[0002] Fluororubber (FKM), a special synthetic rubber, possesses excellent resistance to high temperatures, oils, solvents, acids and alkalis, and weathering. It has irreplaceable applications in extreme environments such as aerospace, automotive manufacturing, electronics, and petrochemicals. With the rapid development of strategic emerging industries such as high-end manufacturing, new energy vehicles, semiconductors, and flexible electronics, the demand for functional materials continues to rise. Conductivity modification of fluororubber has become a key direction for expanding its application areas. Especially in functional devices such as conductive seals, electrostatic protection, electromagnetic shielding, and flexible sensors, the demand for conductive fluororubber is increasingly urgent. It not only needs to meet the requirements of weather resistance and dielectric resistance in extreme environments but also needs to possess stable conductivity and good mechanical compatibility.
[0003] However, due to the inherent structural characteristics of fluororubber and the limitations of existing modification technologies, the conductive modification of fluororubber still suffers from several key performance shortcomings, making it difficult to meet the stringent requirements of high-end functional devices. Specifically: First, the highly symmetrical distribution of fluorine atoms in the fluororubber molecular chain gives it a strong nonpolar characteristic, with weak intermolecular forces and a lack of conductive active sites, resulting in extremely high volume resistivity and a lack of natural conductivity. Second, current technologies mainly modify fluororubber by adding conductive fillers (such as carbon black, carbon nanotubes, metal particles, graphene nanotubes, etc.). However, a certain amount of conductive filler is required to form a continuous conductive network to meet the required conductivity. Adding a large amount of conductive filler significantly damages the inherent mechanical properties of fluororubber, such as elasticity, toughness, and tensile strength, leading to stress concentration, embrittlement, and other problems. It also significantly increases the difficulty of processing such as mixing and sheeting. First, the high degree of conductivity increases production costs and makes it difficult to adapt to the deformation requirements of flexible devices. Second, the polarity difference between conductive fillers (especially carbon-based and metal-based fillers) and fluororubber matrices is large, resulting in poor interfacial compatibility. Agglomeration is prone to occur during mixing and subsequent use, which not only leads to uneven distribution of conductivity and insufficient stability, making it impossible to achieve long-term stable conductivity, but also disrupts the continuity of the fluororubber matrix, further deteriorating the material's resistance to oil, solvents, high-temperature aging, and other environmental properties, shortening the lifespan of the device. Third, ionic liquids have excellent conductivity, thermal stability, and non-volatile properties, and are expected to be used in fluororubber to build a stable conductive network to improve its conductivity. However, the interfacial compatibility between ionic liquids and fluororubber matrices is poor, and direct addition is prone to migration and leakage problems, making it difficult to form a uniform and stable conductive network and failing to achieve a synergistic improvement in conductivity and mechanical properties.
[0004] In summary, existing research largely focuses on single-path modifications such as single conductive filler modification or physical addition of ionic liquids. While these methods can improve the conductivity of fluororubber to some extent, they fail to overcome the bottleneck of achieving a synergistic balance between conductivity and mechanical properties, thus failing to meet the needs of high-end functional devices in fields such as aerospace, new energy vehicles, semiconductors, and flexible wearables. Therefore, developing a conductive modification technology for fluororubber that can synergistically improve both conductivity and mechanical properties has significant practical implications and industrial application value. Summary of the Invention
[0005] The purpose of this invention is to provide a conductive fluororubber based on in-situ polymerized ionic liquid-polyurethane modification, its preparation method, and its uses.
[0006] This invention provides a fluororubber, which is made from raw materials comprising the following parts by weight: 50-90 parts of fluororubber raw rubber, 10-50 parts of in-situ polymerized ionic liquid-polyurethane modifier, 1-3 parts of vulcanizing agent, 0.5-2 parts of vulcanization accelerator, and 2-5 parts of acid scavenger; the mass ratio of the fluororubber raw rubber to the in-situ polymerized ionic liquid-polyurethane modifier is 1:1 to 9:1; the in-situ polymerized ionic liquid-polyurethane modifier is obtained by in-situ polymerization of raw materials including polyol, isocyanate, chain extender and ionic liquid.
[0007] Furthermore, the raw materials also include 5-15 parts of reinforcing filler and 0.1-1 parts of internal release agent.
[0008] Further, the vulcanizing agent is selected from at least one of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexyn-3, or dicumyl peroxide; the vulcanization accelerator is selected from at least one of triallyl isocyanurate, trimethylolpropane trimethacrylate, or divinylbenzene; the reinforcing filler is selected from at least one of calcium silicate, diatomaceous earth VM56, and calcium carbonate; the acid absorber is selected from at least one of zinc oxide, calcium oxide, and magnesium oxide; and the internal release agent is selected from at least one of No. 2 wax, WS280, and FPA-1.
[0009] Furthermore, the in-situ polymerized ionic liquid-polyurethane modifier is prepared from raw materials comprising the following parts by weight: 8-12 parts isocyanate, 30-35 parts polyol, 1-5 parts ionic liquid, and 1-3 parts chain extender.
[0010] Further, the isocyanate is selected from at least one of diphenylmethane diisocyanate, toluene diisocyanate, and hexamethylene diisocyanate; the polyol is selected from at least one of polycarbonate diol, polytetrahydrofuran diol, and polycaprolactone diol; the ionic liquid is a functionalized ionic liquid containing active hydroxyl or amino groups; and the chain extender is selected from at least one of ethylene glycol, 1,4-butanediol, and diethanolamine.
[0011] Further, the functionalized ionic liquid containing active hydroxyl groups is selected from at least one of 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, 1-hydroxyethyl-3-methylimidazolium chloride, 1-hydroxyethyl-3-methylimidazolium hexafluorophosphate, and 1-hydroxypropyl-3-methylimidazolium tetrafluoroborate; the functionalized ionic liquid containing active amino groups is selected from at least one of 1-aminopropyl-3-methylimidazolium hexafluorophosphate, 1-aminopropyl-3-methylimidazolium tetrafluoroborate, 1-aminopropyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-aminoethyl-3-methylimidazolium tetrafluoroborate; and the number average molecular weight of the polyol is 1000~3000.
[0012] Further, the in-situ polymerized ionic liquid-polyurethane modifier is prepared by the following steps: (1) dehydrating the polyol, adding isocyanate and catalyst to react and obtain a mixed system; (2) adding chain extender, ionic liquid and organic solvent to the mixed system to react, and drying after the reaction to obtain the in-situ polymerized ionic liquid-polyurethane modifier.
[0013] Further, the catalyst is 0.01 to 0.1 parts by weight; the organic solvent is 40 to 60 parts by weight; the catalyst is selected from at least one of dibutyltin dilaurate and triethylenediamine; the organic solvent is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, and ethyl acetate.
[0014] Further, in step (1), the polyol is dehydrated under vacuum at 100~110℃ for 1~2h, cooled to 80~100℃, and isocyanate and catalyst are added and reacted for 2~3h to obtain a mixed system; in step (2), the reaction temperature is 40~60℃, the time is 15~18h, and the drying temperature is 80~100℃.
[0015] The present invention also provides a method for preparing fluororubber, including the following steps: (1) mixing: plasticizing the fluororubber raw rubber, then adding the in-situ polymerized ionic liquid-polyurethane modifier and mixing evenly, then adding the reinforcing filler and acid absorber and mixing evenly, then adding the vulcanizing agent, vulcanization accelerator and internal release agent and mixing, and after open milling, thin pass, sheeting and standing, performing secondary re-milling to obtain the mixed rubber; (2) vulcanization: molding the mixed rubber in a mold, and then performing secondary vulcanization to obtain the final product.
[0016] Further, in step (1), the plasticizing temperature is 50~60℃, the rotation speed is 30~40rpm, and the time is 8~10min; the mixing time for adding in-situ polymerized ionic liquid-polyurethane modifier is 10~15min; the mixing speed for adding reinforcing filler and acid absorbent is 10~20rpm and the time is 8~12min; the mixing time for adding vulcanizing agent, vulcanization accelerator and internal release agent is 5~10min; and the standing time is greater than 24h. In step (2), the molding conditions are 170~180℃, 10~20MPa, and 5~15min; and the secondary vulcanization conditions are 170~180℃ and 2~3h.
[0017] The present invention also provides the use of fluororubber in the preparation of conductive seals, electrostatic protection components, electromagnetic shielding elements and flexible sensors.
[0018] This invention introduces an in-situ polymerized ionic liquid-polyurethane modifier into the preparation system of fluororubber, chemically bonding the ionic liquid to the polyurethane molecular chain. This solves the problems of easy migration and leakage caused by the physical addition of ionic liquids in traditional methods, ensuring the long-term stability of the conductivity of fluororubber. Excellent conductivity can be achieved without adding a large amount of conductive filler. At the same time, polyurethane acts as a "bridge," effectively improving the interfacial compatibility between the ionic liquid and fluororubber, avoiding the performance degradation caused by the agglomeration of conductive filler, and enabling the modifier to be uniformly dispersed in the fluororubber matrix, constructing a continuous and stable ionic conductive network, and significantly improving the conductivity uniformity of fluororubber.
[0019] Furthermore, this invention precisely controls the mass ratio of fluororubber raw rubber and in-situ polymerized ionic liquid-polyurethane modifier. When the mass ratio is between 1:1 and 9:1, the conductivity and elongation at break of fluororubber can be improved simultaneously while maintaining high hardness and tensile strength. When the mass ratio is less than 1:1, the elongation at break, hardness, and tensile strength of the resulting fluororubber are significantly reduced, which is detrimental to the mechanical properties of fluororubber.
[0020] In summary, this invention utilizes in-situ polymerization to prepare an in-situ polymerized ionic liquid-polyurethane modifier. By adding the in-situ polymerized ionic liquid-polyurethane modifier and controlling its mass ratio with fluororubber raw material, a synergistic improvement in the conductivity and toughness of fluororubber is achieved. This results in a fluororubber with both high conductivity and excellent mechanical properties, which can meet the comprehensive performance requirements of aerospace, new energy vehicles, semiconductors, and flexible wearable devices for material conductivity, sealing, and protection. It also shows promising application prospects in conductive sealing, electrostatic protection, electromagnetic shielding, and flexible sensors.
[0021] Obviously, based on the above description of the present invention, and according to common technical knowledge and conventional methods in the field, various other modifications, substitutions or alterations can be made without departing from the basic technical concept of the present invention.
[0022] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following embodiments. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Detailed Implementation
[0023] The raw materials and equipment used in this invention are all known products, obtained by purchasing commercially available products.
[0024] In a specific embodiment of the present invention, the fluororubber raw material is a domestically produced peroxyfluororubber with a Mooney viscosity (ML1+10, 121℃) of 28, purchased from Dongyue Fluorosilicon Technology Group Co., Ltd., and the model is 246 fluororubber.
[0025] Example 1: Preparation of Fluororubber 1.1 Preparation of in-situ polymerized ionic liquid-polyurethane modifier Formula (parts by weight): 10 parts diphenylmethane diisocyanate (MDI), 33 parts polytetrahydrofuran diol (number average molecular weight 2000), 3 parts ionic liquid (1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt), 2 parts chain extender (1,4-butanediol), 0.05 parts catalyst (dibutyltin dilaurate), and 52 parts organic solvent (N,N-dimethylformamide); Prepare according to the formula as follows: (1) Add polytetrahydrofuran diol to the reaction vessel and dehydrate it under vacuum at 110°C for 1 hour to remove moisture; (2) Cool the dehydrated polytetrahydrofuran diol to 90°C, add MDI and catalyst and react for 3 hours to obtain a mixed system; (3) Control the reaction temperature to 60℃, add chain extender, ionic liquid and organic solvent to the mixed system, react for 16h, pour into a mold, remove the solvent in an oven at 100℃, and obtain in-situ polymerized ionic liquid-polyurethane modifier.
[0026] 1.2 Preparation of Conductive Fluororubber Formula (parts by weight): 90 parts of fluororubber raw rubber, 10 parts of in-situ polymerized ionic liquid-polyurethane modifier, 2.5 parts of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 2 parts of triallyl isocyanurate, 15 parts of calcium silicate, 5 parts of zinc oxide, and 1 part of internal release agent (WS280). Prepare according to the formula as follows: (1) Mixing: Add the fluororubber raw rubber to the internal mixer, control the temperature at 50℃ and the speed at 30rpm, and plasticize for 8min; then add the in-situ polymerized ionic liquid-polyurethane modifier and continue mixing for 10min; then reduce the speed of the internal mixer to 15rpm, slowly add calcium silicate and zinc oxide, and mix at low speed for 8min; then add 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, triallyl isocyanurate and internal release agent, mix for 8min, transfer to the open mill and pass through the triangular bag 5 times to get the sheet, let it stand for 24h and then perform a second re-mixing to obtain the compound rubber; (2) Vulcanization: The compound rubber is placed into a mold and molded in a flat vulcanizing machine at 180°C, 14MPa and 10min. Then it is vulcanized in an oven at 180°C for 2 hours to obtain fluororubber.
[0027] Example 2: Preparation of Fluororubber Referring to Example 1, the only difference is that in the formulation of 1.2, the fluororubber raw rubber is 90 parts and the in-situ polymerized ionic liquid-polyurethane modifier is 30 parts.
[0028] Example 3: Preparation of Fluororubber Referring to Example 1, the only difference is that in the formulation of 1.2, the fluororubber raw rubber is 50 parts and the in-situ polymerized ionic liquid-polyurethane modifier is 50 parts.
[0029] Comparative Example 1: Preparation of Fluororubber Referring to Example 1, the only difference is that in the formulation of 1.2, the fluororubber raw rubber is 40 parts and the in-situ polymerized ionic liquid-polyurethane modifier is 60 parts.
[0030] Comparative Example 2: Preparation of Fluororubber Referring to Example 1, the only difference is that in the formulation of 1.2, the fluororubber raw rubber is 100 parts, and no in-situ polymerized ionic liquid-polyurethane modifier is added.
[0031] Experimental Examples and Performance Testing of Fluororubber 1. Experimental Methods The Shore A hardness of the sample was tested according to GB / T 531.1-2008 standard.
[0032] According to GB / T 528-2009 standard, the tensile strength and elongation at break of the samples were tested.
[0033] According to GB / T 1410-2006 standard, the volume resistivity of the sample was tested.
[0034] 2. Experimental Results As shown in Table 1, compared with Comparative Example 2 without the addition of in-situ polymerized ionic liquid-polyurethane modifier, the volume resistivity of the fluororubber prepared in Examples 1-3 and Comparative Example 1 after the addition of in-situ polymerized ionic liquid-polyurethane modifier was significantly reduced, indicating that the addition of in-situ polymerized ionic liquid-polyurethane modifier can improve the conductivity of fluororubber.
[0035] Further comparison of Examples 1-3 and Comparative Example 1 shows that as the mass ratio of fluororubber raw rubber to in-situ polymerized ionic liquid-polyurethane modifier decreases, i.e., the proportion of in-situ polymerized ionic liquid-polyurethane modifier increases, the conductivity of the obtained fluororubber increases. Meanwhile, compared to Comparative Example 2 without the addition of in-situ polymerized ionic liquid-polyurethane modifier, the fluororubber obtained in Examples 1-3 with a mass ratio of fluororubber raw rubber to in-situ polymerized ionic liquid-polyurethane modifier of 1:1 to 9:1 exhibits significantly improved elongation at break, while its Shore hardness and tensile strength remain at a high level. However, the fluororubber obtained in Comparative Example 1 with a mass ratio of fluororubber raw rubber to in-situ polymerized ionic liquid-polyurethane modifier of 4:6 shows a significant decrease in hardness, tensile strength, and elongation at break (compared to Comparative Example 2, its tensile strength decreased by 37.3%, and its elongation at break decreased by 13.2%).
[0036] The above results indicate that adding an in-situ polymerized ionic liquid-polyurethane modifier can improve the conductivity of fluororubber. However, the mass ratio of fluororubber raw rubber to in-situ polymerized ionic liquid-polyurethane modifier needs to be controlled within a specific range (1:1 to 9:1 used in Examples 1 to 3) in order to simultaneously improve the conductivity and elongation at break of fluororubber while maintaining high hardness and tensile strength.
[0037] Table 1. Performance test data of fluororubber In summary, this invention utilizes in-situ polymerization to prepare an in-situ polymerized ionic liquid-polyurethane modifier. By adding the in-situ polymerized ionic liquid-polyurethane modifier and controlling its mass ratio with fluororubber raw material, fluororubber exhibiting both high conductivity and excellent mechanical properties is obtained. Experiments demonstrate that when the mass ratio of fluororubber raw material to in-situ polymerized ionic liquid-polyurethane modifier is between 1:1 and 9:1, the conductivity and elongation at break of the fluororubber can be improved simultaneously while maintaining high hardness and tensile strength. When the mass ratio of fluororubber raw material to in-situ polymerized ionic liquid-polyurethane modifier is less than 1:1, the elongation at break, hardness, and tensile strength of the resulting fluororubber are significantly reduced, which is detrimental to the mechanical properties of the fluororubber.
Claims
1. A fluororubber, characterized in that, It is made from raw materials comprising the following parts by weight: 50-90 parts of fluororubber raw rubber, 10-50 parts of in-situ polymerized ionic liquid-polyurethane modifier, 1-3 parts of vulcanizing agent, 0.5-2 parts of vulcanization accelerator, and 2-5 parts of acid scavenger; the mass ratio of the fluororubber raw rubber to the in-situ polymerized ionic liquid-polyurethane modifier is 1:1 to 9:1; the in-situ polymerized ionic liquid-polyurethane modifier is prepared by in-situ polymerization of raw materials including polyol, isocyanate, chain extender and ionic liquid.
2. The fluororubber according to claim 1, characterized in that, The raw materials also include 5-15 parts of reinforcing filler and 0.1-1 parts of internal release agent.
3. The fluororubber according to claim 2, characterized in that, The vulcanizing agent is selected from at least one of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexyn-3, or dicumyl peroxide; the vulcanization accelerator is selected from at least one of triallyl isocyanurate, trimethylolpropane trimethacrylate, or divinylbenzene; the reinforcing filler is selected from at least one of calcium silicate, diatomaceous earth VM56, and calcium carbonate; the acid absorber is selected from at least one of zinc oxide, calcium oxide, and magnesium oxide; and the internal release agent is selected from at least one of No. 2 wax, WS280, and FPA-1.
4. The fluororubber according to claim 1, characterized in that, The in-situ polymerized ionic liquid-polyurethane modifier is prepared from raw materials comprising the following parts by weight: 8-12 parts isocyanate, 30-35 parts polyol, 1-5 parts ionic liquid, and 1-3 parts chain extender.
5. The fluororubber according to claim 4, characterized in that, The isocyanate is selected from at least one of diphenylmethane diisocyanate, toluene diisocyanate, and hexamethylene diisocyanate; the polyol is selected from at least one of polycarbonate diol, polytetrahydrofuran diol, and polycaprolactone diol; the ionic liquid is a functionalized ionic liquid containing active hydroxyl or amino groups; and the chain extender is selected from at least one of ethylene glycol, 1,4-butanediol, and diethanolamine.
6. The fluororubber according to claim 5, characterized in that, The functionalized ionic liquid containing active hydroxyl groups is selected from at least one of 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, 1-hydroxyethyl-3-methylimidazolium chloride, 1-hydroxyethyl-3-methylimidazolium hexafluorophosphate, and 1-hydroxypropyl-3-methylimidazolium tetrafluoroborate; the functionalized ionic liquid containing active amino groups is selected from at least one of 1-aminopropyl-3-methylimidazolium hexafluorophosphate, 1-aminopropyl-3-methylimidazolium tetrafluoroborate, 1-aminopropyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-aminoethyl-3-methylimidazolium tetrafluoroborate; the number average molecular weight of the polyol is 1000~3000.
7. The fluororubber according to any one of claims 4-6, characterized in that, The in-situ polymerized ionic liquid-polyurethane modifier is prepared by the following steps: (1) dehydrating the polyol, adding isocyanate and catalyst to react and obtain a mixed system; (2) adding chain extender, ionic liquid and organic solvent to the mixed system to react and dry after the reaction to obtain the in-situ polymerized ionic liquid-polyurethane modifier.
8. The fluororubber according to claim 7, characterized in that, The catalyst has a weight ratio of 0.01 to 0.1 parts; the organic solvent has a weight ratio of 40 to 60 parts; the catalyst is selected from at least one of dibutyltin dilaurate and triethylenediamine; the organic solvent is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, and ethyl acetate.
9. The method for preparing fluororubber according to any one of claims 1-8, characterized in that, The steps include: (1) Mixing: Plasticize the fluororubber raw rubber, then add the in-situ polymerized ionic liquid-polyurethane modifier and mix evenly, then add the reinforcing filler and acid absorber and mix evenly, then add the vulcanizing agent, vulcanization accelerator and internal release agent and mix, after open milling, thin pass, sheeting and resting, perform secondary re-milling to obtain the mixed rubber; (2) Vulcanization: Mold the mixed rubber in the mold and then perform secondary vulcanization to obtain the final product.
10. Use of the fluororubber according to any one of claims 1-8 in the preparation of conductive seals, electrostatic protection components, electromagnetic shielding elements and flexible sensors.