Flame-retardant and oil-resistant inner-fluorine and outer-silicon rubber tube material and preparation method thereof

Abstract

The present application relates to the technical field of rubber tube, and particularly relates to a flame-retardant oil-resistant inner-fluorine outer-silicon rubber tube material and a preparation method thereof. The flame-retardant oil-resistant inner-fluorine outer-silicon rubber tube material comprises, from inside to outside, an inner-fluorine rubber layer, a calendered cloth layer and a silicon rubber layer. The inner-fluorine rubber layer is prepared from the following raw materials in parts by weight: FKM mixed rubber 50-70 parts, FVMQ mixed rubber 40 parts; wherein the FKM mixed rubber is prepared from the following raw materials in parts by weight: FKM 60-80 parts, carbon black 15-25 parts, barium sulfate 8-14 parts, modified magnesium hydroxide whisker 5-10 parts, plasticizer 6-12 parts, vulcanization aid 2-6 parts; and the FVMQ mixed rubber is prepared from the following raw materials in parts by weight: FVMQ 20-28 parts, polytetrafluoroethylene micro powder 6-12 parts, lignin sulfonate 4-8 parts, lubricant 0.5-2.5 parts. The rubber tube material prepared by the present application has not only good mechanical properties, but also high flame retardancy and good oil resistance.

Description

Technical Field

[0001] This invention relates to the field of hose technology, specifically to a flame-retardant and oil-resistant inner fluoropolymer outer silicone tube material and its preparation method. Background Technology

[0002] In fields such as automotive fuel delivery, industrial fluid transmission, hydraulic systems for electromechanical equipment, and high-temperature chemical processes, pipeline materials constantly face complex operating conditions including high temperatures, oil erosion, open flame hazards, and mechanical bending. This places stringent requirements on the oil resistance, flame retardancy, high and low temperature tolerance, and structural stability of the pipe materials. Silicone, with its excellent high and low temperature resistance, flexibility, insulation, and aging resistance, has become the mainstream outer layer material for special hoses. Fluorinated polymers, on the other hand, possess extremely strong oil resistance, chemical corrosion resistance, and low permeability, effectively blocking the erosion of oil and hydrocarbon media. Therefore, fluorinated inner and silicone outer composite pipes have become core pipeline accessories suitable for harsh operating conditions and are widely used in various high-risk fluid transportation scenarios, becoming a key research focus in this field.

[0003] Patent CN10686386B discloses a method for preparing an inner fluorine and outer silicone automotive hose. The method involves weighing various materials required for different silicone rubber formulations according to the formula proportions, mixing the silicone rubber (excluding the vulcanizing agent) and other ingredients in a mixing mill, letting the mixed silicone rubber stand for 24 hours, adding the vulcanizing agent, and mixing again. After the second mixing, the hose is calendered into sheets. Similarly, various materials required for different fluororubber formulations are weighed according to the formula proportions and mixed evenly on a rubber mixing mill. Both mixed rubbers are left to stand for 24 hours, then mixed again in a rubber mixing mill until uniform, and finally calendered into sheets. A mold is used for the product; the molded product is placed in a vulcanizing tank for a first-stage vulcanization. After this step, the outer film is removed from the mold for a second-stage vulcanization. After the entire molding process is complete, the hose is cleaned and the end is cut to obtain the final product.

[0004] However, existing conventional fluorine-insulated and silicone-insulated composite pipes have simple formulations and lack targeted optimization of the flame-retardant system. They are prone to combustion and dripping in high-temperature and high-heat environments, resulting in low fire safety levels. They are unsuitable for high-risk working conditions involving confined spaces, high temperatures, and flammable and explosive environments, and fail to meet the current demands for industrial equipment upgrades and safe production. Therefore, developing a flame-retardant and oil-resistant fluorine-insulated and silicone-insulated pipe material with superior overall performance and adaptability to complex and harsh working conditions has become a key focus and urgent need in this field of technological research. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of this invention is to obtain an inner fluorine and outer silicone tube material that not only has good mechanical properties, but also high flame retardancy and good oil resistance.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a flame-retardant and oil-resistant inner fluoropolymer and outer silicone tube material. The tube material comprises, from the inside out, an inner fluoropolymer layer, a calendered fabric layer, and a silicone layer. The inner fluoropolymer layer, by weight, comprises the following raw materials: 50-70 parts of FKM compound and 40 parts of FVMQ compound. The FKM compound, by weight, comprises the following raw materials: 60-80 parts of FKM; 15-25 parts of carbon black; 8-14 parts of barium sulfate; 5-10 parts of modified magnesium hydroxide whiskers; 6-12 parts of plasticizer; and 2-6 parts of vulcanization aid. The FVMQ compound, by weight, comprises the following raw materials: 20-28 parts of FVMQ; 6-12 parts of polytetrafluoroethylene micropowder; 4-8 parts of lignin sulfonate; and 0.5-2.5 parts of lubricant.

[0007] In some embodiments, the method for preparing the modified magnesium hydroxide whiskers includes the following steps: (1) Add magnesium hydroxide whiskers to deionized water and adjust the pH to 4-5 with acetic acid. Stir and activate at 50-60°C for 1-2 hours. Filter, wash and dry to obtain pretreated magnesium hydroxide whiskers. (2) Add the pretreated magnesium hydroxide whiskers prepared in step (1) to the solvent, adjust the pH to 5-6 with acetic acid, add silane coupling agent, stir and react at 60-70°C for 2-3h, then add 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt and catalyst, heat to 70-85°C, stir and react for 4-6h, filter, wash and dry, grind and sieve to obtain modified magnesium hydroxide whiskers.

[0008] Traditional magnesium hydroxide whiskers have a high surface polarity, making them prone to agglomeration when directly added to a non-polar FKM matrix, thus hindering their reinforcing and flame-retardant effects. This invention addresses this by using acetic acid activation to etch more active hydroxyl groups onto the whisker surface, providing abundant reaction sites for subsequent coupling. Then, a silane coupling agent combined with 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt is used for functional modification, constructing an organic coating layer rich in imidazole ionic liquid on the whisker surface. This significantly reduces the surface energy of the whiskers and greatly enhances their affinity for the FKM molecular chains. The fluorosulfonylimide groups in the ionic liquid form a strong interfacial interaction with the fluororubber matrix, achieving nanoscale uniform dispersion of the whiskers in the rubber phase. Furthermore, the imidazole ionic liquid layer anchored to the whisker surface has both catalytic and char-forming effects, enabling combustion... Catalysis promotes the dehydration and char formation of the FKM and FVMQ matrix, creating a dense and stable heat-insulating protective char layer. Simultaneously, water vapor released from the whisker decomposition carries away heat and dilutes combustible gases. This synergistic mechanism of solid-phase char formation and gas-phase flame retardancy allows the material to maintain excellent flame-retardant properties even under flame impact. Furthermore, the high specific surface area of ​​the whiskers and their strong interfacial bonding with the matrix create a "maze effect," extending the penetration path of oil molecules within the adhesive layer and effectively reducing the swelling rate. On the other hand, the fluorinated ionic liquid component on the whisker surface possesses excellent oleophobic properties, establishing a molecular-level oil penetration barrier at the filler-matrix interface, preventing oil from diffusing into the adhesive layer. This microstructural design breaks through the technical bottleneck of traditional oil-resistant rubber formulations where flame retardancy and oil resistance are difficult to achieve simultaneously.

[0009] In some embodiments, the silane coupling agent in step (1) is a silane coupling agent containing an epoxy group.

[0010] In some embodiments, the mass ratio of the pretreated magnesium hydroxide whiskers to the silane coupling agent in step (2) is 1:(0.02-0.06).

[0011] In some embodiments, the mass ratio of the pretreated magnesium hydroxide whiskers to 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt in step (2) is 1:(0.03-0.08).

[0012] In some embodiments, the amount of catalyst added is 1-3% of the mass of 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt.

[0013] In some embodiments, the D50 of the polytetrafluoroethylene micropowder is 5-10 μm.

[0014] In some embodiments, the silicone layer is prepared from a silicone sheet, which is prepared from a compound flame retardant and methyl vinyl silicone rubber, methyl MQ silicone resin and bis(2,5-dimethyl) sulfide.

[0015] In some embodiments, the calendered fabric layer is prepared from calendered fabric, and the method for preparing the calendered fabric includes the following steps: The fumed silica gel is mixed on an open mill for 10-15 minutes, then sheeted with a thickness of 0.1-0.3 mm. After resting, it is re-mixed on the open mill and then calendered at 60-70℃ on a calender to obtain calendered fabric, which is then cut.

[0016] The second aspect of this invention provides a method for preparing a flame-retardant and oil-resistant inner fluoropolymer and outer silicone tubing material, comprising the following steps: S1. FKM is mixed with carbon black, barium sulfate, modified zinc oxide whiskers, plasticizer, and vulcanization aid on a low-temperature roller to obtain FKM compound; FVMQ is mixed with lignin sulfonate, polytetrafluoroethylene micro powder, and lubricant on a high-temperature roller to obtain FVMQ compound. S2. After the FKM compound and FVMQ compound obtained in step S1 are left to stand, they are added to the internal mixer for mixing; during the mixing process in the internal mixer, the mixture is stretched 5-10 times, and then sheeted on a calender to obtain fluororubber. S3. The fluororubber obtained in step S2 is wound onto a straight mandrel to form an inner fluororubber layer. Calendered fabric is wound onto the surface of the inner fluororubber layer to form a calendered fabric layer. A silicone sheet is wound onto the surface of the calendered fabric layer to form a silicone layer. Finally, a PET film is wound onto the outermost layer to obtain a mandrel-supported tube blank. The thickness of the inner fluororubber layer is 0.1-0.3 mm. S4. Exhaust the mandrel-supported tube blank obtained in step S4 on an exhaust machine. After exhausting, remove the tube blank from the straight mandrel to obtain the tube blank sleeve. S5. Place the tube blank obtained in step S4 onto the mold of the required shape, place it in a vulcanizing tank for vulcanization, remove the obtained tube from the mold after exiting the tank, remove the PET film for secondary vulcanization, clean, cut, inspect, package and store to obtain an inner fluorine outer silicone tube.

[0017] In some embodiments, the vulcanization temperature in step S5 is 150-175°C and the time is 30-60 min, while the secondary vulcanization temperature is 180-190°C and the time is 2-3 h.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention prepares an inner fluorinated rubber layer by using FKM compound rubber and FVMQ compound rubber, and then combines it with calendered cloth and silicone sheet to prepare an inner fluorinated outer silicone tube material, which not only has good mechanical properties, but also has high flame retardancy and good oil resistance.

[0019] (2) In this invention, the active hydroxyl groups of the whiskers are first increased by acetic acid activation, and then an organic coating layer is constructed on the surface of the whiskers by composite modification with silane coupling agent and imidazole ionic liquid. This modification method improves the compatibility between the whiskers and the matrix, achieves uniform dispersion at the nanoscale, enhances the flame retardant performance by relying on the synergistic effect of solid-phase char formation and gas-phase flame retardancy, and improves the oil resistance of the material by utilizing the labyrinth effect and the oleophobic properties of ionic liquid, thus overcoming the technical problem of not being able to achieve both flame retardancy and oil resistance. Detailed Implementation

[0020] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0021] In the following examples and comparative examples, the compounds and related reagents used were all commercially available. The polytetrafluoroethylene (PTFE) micropowder was grade F284, D50=9μm, and manufactured by Solvay. The carbon black was purchased from Tianjin Baochi Chemical Technology Co., Ltd., model N990. The plasticizer was purchased from Shanzhen Industrial (Shanghai) Co., Ltd., model RS-107. The magnesium hydroxide whiskers were single-crystal fibrous, with a diameter of 0.05-1μm and a length of 2-20μm, and were purchased from Yingkou Wesker Chemical Co., Ltd. FVM Q was purchased from Renze District Shuode Rubber & Plastic Sealing Parts Factory, model A01; FKM grade is G902; methyl MQ silicone resin grade is AM-8080, purchased from Shandong Qisheng New Material Technology Co., Ltd.; methyl vinyl silicone rubber, vinyl content 0.15-0.2 mol%, purchased from Shenzhen Huacan Silicone Rubber Technology Co., Ltd.; lubricant is Rheinland 25, manufacturer is Rheinland Chemicals; ammonium polyphosphate was purchased from Shandong Huian Chemical Co., Ltd.; sodium lignosulfonate was purchased from Donghao Chemical (Shandong) Co., Ltd.

[0022] Unless otherwise specified, the post-processing steps such as "washing" and "drying" used below are routine operations for those skilled in the art, and can be selected according to actual operations.

[0023] Preparation Example 1 The preparation method of modified magnesium hydroxide whiskers-1 includes the following steps: (1) Add 20g of magnesium hydroxide whiskers to 500ml of deionized water and adjust the pH to 4 with acetic acid. Stir and activate at 55°C for 1.5h. Filter, wash and dry to obtain pretreated magnesium hydroxide whiskers. (2) Add 10g of the pretreated magnesium hydroxide whiskers prepared in step (1) to 500ml of 97wt% ethanol solution, adjust the pH to 5.5 with acetic acid, add 0.5g of γ-glycidyl etheroxypropyltrimethoxysilane, stir and react at 65°C for 2.5h, then add 0.5g of 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and 0.01g of triethylamine, heat to 75°C, stir and react for 5h, filter while hot, wash and dry with anhydrous ethanol, grind and pass through a 200-mesh sieve to obtain modified magnesium hydroxide whiskers-1.

[0024] Preparation Example 2 The preparation method of modified magnesium hydroxide whiskers-2 is the same as that in preparation example 1, except that the amount of γ-glycidoxypropyltrimethoxysilane added is 0.8g.

[0025] Preparation Example 3 The preparation method of modified magnesium hydroxide whiskers-3 is the same as that in Preparation Example 1, except that the amount of 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt added is 0.9g.

[0026] Preparation Example 4 The method for preparing calendered fabric includes the following steps: The fumed silica gel was mixed on a two-roll mill for 12 minutes, then sheeted with a thickness of 0.2 mm. After resting for 24 hours, it was re-mixed on the two-roll mill and then calendered at 65°C on a calender to obtain calendered fabric, which was then cut.

[0027] Preparation Example 5 The preparation method of silicone sheet-1 includes the following steps: 1) Mix 30g of ammonium polyphosphate and 20g of melamine cyanurate evenly, add 1ml of 95wt% ethanol aqueous solution containing 0.1g KH550 at 1000rpm, stir at 80℃ for 20min to obtain the compound flame retardant. 2) By weight, 100 parts of methyl vinyl silicone rubber were plasticized in a kneader for 5 minutes. 24 parts of methyl MQ silicone resin were added in three batches and mixed evenly. Then, 10 parts of the compound flame retardant obtained in step 1) were added in three batches and mixed for 15 minutes. After the sheet was cooled and left to stand for 24 hours, 2 parts of bis(2,5) vulcanizing agent were added at a roller temperature of 45°C. The sheet was passed through 8 times and the thickness of the sheet was 0.3 mm to obtain silicone sheet-1.

[0028] Preparation Example 6 The preparation method of silicone sheet-2 includes the following steps: 1) Mix 30g of ammonium polyphosphate and 20g of melamine cyanurate evenly to obtain a compound flame retardant; 2) By weight, 100 parts of methyl vinyl silicone rubber were plasticized in a kneader for 5 minutes. 24 parts of methyl MQ silicone resin were added in three batches and mixed evenly. Then, 20 parts of the compound flame retardant obtained in step 1) were added in three batches and mixed for 15 minutes. After the sheet was cooled and left to stand for 24 hours, 2 parts of bis(2,5) vulcanizing agent were added at a roller temperature of 45°C. The sheet was passed through 8 times and the thickness of the sheet was 0.3 mm to obtain silicone sheet-2.

[0029] Example 1 A flame-retardant and oil-resistant inner fluoropolymer and outer silicone tubing material, wherein the tubing material comprises, from the inside out, an inner fluoropolymer layer, a calendered fabric layer, and a silicone layer. The inner fluoropolymer layer, by weight, comprises the following raw materials: 60 parts of FKM compound and 40 parts of FVMQ compound. The FKM compound, by weight, comprises the following raw materials: 70 parts of FKM; 20 parts of carbon black; 11 parts of barium sulfate; 8 parts of modified magnesium hydroxide whiskers-1; 9 parts of plasticizer; and 5 parts of vulcanizing agent TAIC. The FVMQ compound, by weight, comprises the following raw materials: 24 parts of FVMQ; 9 parts of polytetrafluoroethylene micropowder; 6 parts of sodium lignosulfonate; and 1.5 parts of lubricant.

[0030] The preparation method of the flame-retardant and oil-resistant inner fluoropolymer outer silicone tubing material in this embodiment includes the following steps: S1. Mix FKM with carbon black, barium sulfate, modified zinc oxide whiskers-1, plasticizer, and vulcanization aid TAIC evenly on a low-temperature roller to obtain FKM compound; mix FVMQ with sodium lignosulfonate, polytetrafluoroethylene micro powder, and lubricant evenly on a high-temperature roller to obtain FVMQ compound. S2. After the FKM compound and FVMQ compound obtained in step S1 are left to stand for 24 hours, they are added to the internal mixer for mixing. During the mixing process in the internal mixer, the mixture is stretched 8 times, and then sheeted on a calender to obtain fluororubber. The calendering temperature is 65℃ and the sheet thickness is 0.2mm. S3. The fluororubber obtained in step S2 is wound onto a straight mandrel to form an inner fluororubber layer. Four layers of calendered fabric are wound around the surface of the inner fluororubber layer to obtain a calendered fabric layer with a thickness of 0.8 mm. A layer of silicone sheet-1 is wound around the surface of the calendered fabric layer to obtain a silicone layer with a thickness of 0.3 mm. Finally, a PET film is wound around the outermost layer to obtain a mandrel-supported tube blank. The thickness of the inner fluororubber layer is 0.2 mm. S4. Exhaust the mandrel-supported tube blank obtained in step s4 twice on an exhaust machine. After exhausting, remove the tube blank from the straight mandrel to obtain the tube blank sleeve. S5. Place the tube blank obtained in step S4 onto the mold of the required shape, place it in a vulcanizing tank for primary vulcanization at a temperature of 160℃ for 45 minutes. After removing it from the tank, remove the obtained tube from the mold and remove the PET film for secondary vulcanization at a temperature of 185℃ for 2.5 hours. Clean, cut, inspect, package and store to obtain an inner fluorine outer silicone tube.

[0031] Example 2 A flame-retardant and oil-resistant inner fluoropolymer and outer silicone tubing material, wherein the tubing material comprises, from the inside out, an inner fluoropolymer layer, a calendered fabric layer, and a silicone layer. The inner fluoropolymer layer, by weight, comprises the following raw materials: 50 parts of FKM compound and 40 parts of FVMQ compound. The FKM compound, by weight, comprises the following raw materials: 60 parts of FKM; 15 parts of carbon black; 8 parts of barium sulfate; 5 parts of modified magnesium hydroxide whiskers-1; 6 parts of plasticizer; and 2 parts of vulcanizing agent TAIC. The FVMQ compound, by weight, comprises the following raw materials: 20 parts of FVMQ; 6 parts of polytetrafluoroethylene micropowder; 4 parts of sodium lignosulfonate; and 0.5 parts of lubricant.

[0032] The preparation method of the flame-retardant and oil-resistant inner fluoropolymer outer silicone tubing material in this embodiment includes the following steps: S1. Mix FKM with carbon black, barium sulfate, modified zinc oxide whiskers-1, plasticizer, and vulcanization aid TAIC evenly on a low-temperature roller to obtain FKM compound; mix FVMQ with sodium lignosulfonate, polytetrafluoroethylene micro powder, and lubricant evenly on a high-temperature roller to obtain FVMQ compound. S2. After the FKM compound and FVMQ compound obtained in step S1 are left to stand for 24 hours, they are added to the internal mixer for mixing. During the mixing process in the internal mixer, the mixture is stretched 8 times, and then sheeted on a calender to obtain fluororubber. The calendering temperature is 65℃ and the sheet thickness is 0.2mm. S3. The fluororubber obtained in step S2 is wound onto a straight mandrel to form an inner fluororubber layer. Four layers of calendered fabric are wound around the surface of the inner fluororubber layer to obtain a calendered fabric layer with a thickness of 0.8 mm. A layer of silicone sheet-1 is wound around the surface of the calendered fabric layer to obtain a silicone layer with a thickness of 0.3 mm. Finally, a PET film is wound around the outermost layer to obtain a mandrel-supported tube blank. The thickness of the inner fluororubber layer is 0.2 mm. S4. Exhaust the mandrel-supported tube blank obtained in step s4 twice on an exhaust machine. After exhausting, remove the tube blank from the straight mandrel to obtain the tube blank sleeve. S5. Place the tube blank obtained in step S4 onto the mold of the required shape, place it in a vulcanizing tank for primary vulcanization at a temperature of 150℃ for 60 minutes. After removing it from the tank, remove the obtained tubing from the mold and remove the PET film for secondary vulcanization at a temperature of 180℃ for 3 hours. Clean, cut, inspect, package and store to obtain an inner fluorine outer silicone tube.

[0033] Example 3 A flame-retardant and oil-resistant inner fluoropolymer and outer silicone tubing material, wherein the tubing material comprises, from the inside out, an inner fluoropolymer layer, a calendered fabric layer, and a silicone layer. The inner fluoropolymer layer, by weight, comprises the following raw materials: 70 parts of FKM compound and 40 parts of FVMQ compound. The FKM compound, by weight, comprises the following raw materials: 80 parts of FKM; 25 parts of carbon black; 14 parts of barium sulfate; 5 parts of modified magnesium hydroxide whiskers-1; 6 parts of plasticizer; and 2 parts of vulcanizing agent TAIC. The FVMQ compound, by weight, comprises the following raw materials: 20 parts of FVMQ; 6 parts of polytetrafluoroethylene micropowder; 4 parts of sodium lignosulfonate; and 0.5 parts of lubricant.

[0034] The preparation method of the flame-retardant and oil-resistant inner fluoropolymer outer silicone tubing material in this embodiment includes the following steps: S1. Mix FKM with carbon black, barium sulfate, modified zinc oxide whiskers-1, plasticizer, and vulcanization aid TAIC evenly on a low-temperature roller to obtain FKM compound; mix FVMQ with sodium lignosulfonate, polytetrafluoroethylene micro powder, and lubricant evenly on a high-temperature roller to obtain FVMQ compound. S2. After the FKM compound and FVMQ compound obtained in step S1 are left to stand for 24 hours, they are added to the internal mixer for mixing. During the mixing process in the internal mixer, the mixture is stretched 8 times, and then sheeted on a calender to obtain fluororubber. The calendering temperature is 65℃ and the sheet thickness is 0.2mm. S3. The fluororubber obtained in step S2 is wound onto a straight mandrel to form an inner fluororubber layer. Four layers of calendered fabric are wound around the surface of the inner fluororubber layer to obtain a calendered fabric layer with a thickness of 0.8 mm. A layer of silicone sheet-1 is wound around the surface of the calendered fabric layer to obtain a silicone layer with a thickness of 0.3 mm. Finally, a PET film is wound around the outermost layer to obtain a mandrel-supported tube blank. The thickness of the inner fluororubber layer is 0.2 mm. S4. Exhaust the mandrel-supported tube blank obtained in step s4 twice on an exhaust machine. After exhausting, remove the tube blank from the straight mandrel to obtain the tube blank sleeve. S5. Place the tube blank obtained in step S4 onto the mold of the required shape, place it in a vulcanizing tank for primary vulcanization at a temperature of 175℃ for 30 minutes. After removing it from the tank, remove the obtained tube from the mold and remove the PET film for secondary vulcanization at a temperature of 190℃ for 2 hours. Clean, cut, inspect, package and store to obtain an inner fluorine outer silicone tube.

[0035] Example 4 A flame-retardant and oil-resistant inner fluorine and outer silicone tube material and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that modified magnesium hydroxide whiskers-1 are replaced with modified magnesium hydroxide whiskers-2 in equal amounts.

[0036] Example 5 A flame-retardant and oil-resistant inner fluorine outer silicone tube material and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that modified magnesium hydroxide whiskers-1 are replaced with modified magnesium hydroxide whiskers-3 in equal amounts.

[0037] Example 6 A flame-retardant and oil-resistant inner fluorine outer silicone tube material and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that silicone sheet-1 is replaced with silicone sheet-2 in equal amounts.

[0038] Comparative Example 1 A flame-retardant and oil-resistant inner fluorine outer silicone tube material and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that the modified magnesium hydroxide whiskers-1 are replaced with magnesium hydroxide whiskers in equal amounts.

[0039] Performance testing The flame-retardant and oil-resistant inner fluoropolymer and outer silicone tubing materials obtained in each embodiment and comparative example were subjected to the following tests: 1. Tensile strength: Tested according to GB / T 528-2009; 2. Flame retardancy: Tested according to GB / T 10707-2008; 3. Oil resistance: According to GB / T 1690-2010 test, the hose material was immersed in IRM 903# standard oil at 150℃ for 72h, and the volume change rate (ΔV, %) was determined by the water displacement method. Volume change rate = (volume after immersion - volume before immersion) / volume before immersion × 100%.

[0040] The test results are shown in Table 1: Table 1

[0041] As shown in Table 1, the hose materials prepared in Examples 1-3 exhibit good mechanical properties, flame retardancy, and oil resistance. A comparison of the data from Example 4 and Example 1 reveals that changing the ratio of silane coupling agent to pretreated magnesium hydroxide whiskers leads to excessive silane coupling agent forming multilayer adsorption on the surface of the magnesium hydroxide whiskers, creating new stress concentration points and causing a decrease in the mechanical properties of the hose material. A comparison of the data from Example 5 and Example 1 shows that changing the ratio of pretreated magnesium hydroxide whiskers to 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide may affect the crosslinking of silane and rubber. The reaction reduces the continuity of the flame-retardant char layer, thus decreasing the flame retardancy of the hose material. A comparison between Example 6 and Example 1 shows that ammonium polyphosphate and melamine cyanurate are unevenly dispersed in the silicone matrix, failing to form a continuous flame-retardant char layer, thus reducing the flame retardancy of the hose material. A comparison between Comparative Example 1 and Example 1 shows that unmodified magnesium hydroxide whiskers have poor compatibility with the fluororubber matrix, easily forming stress concentration points, leading to a decrease in the mechanical properties of the hose material. Simultaneously, the agglomerated whiskers cannot uniformly block heat, and oil easily penetrates into the interface gaps, resulting in a decrease in the flame retardancy and oil resistance of the hose material.

[0042] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A flame-retardant and oil-resistant inner fluoropolymer and outer silicone tubing material, characterized in that, The hose material, from the inside out, consists of an inner fluoropolymer layer, a calendered fabric layer, and a silicone layer. The inner fluoropolymer layer, by weight, comprises the following raw materials: 50-70 parts of FKM compound and 40 parts of FVMQ compound. The FKM compound, by weight, comprises the following raw materials: 60-80 parts of FKM; 15-25 parts of carbon black; 8-14 parts of barium sulfate; 5-10 parts of modified magnesium hydroxide whiskers; 6-12 parts of plasticizer; and 2-6 parts of vulcanization aid. The FVMQ compound, by weight, comprises the following raw materials: 20-28 parts of FVMQ; 6-12 parts of polytetrafluoroethylene micropowder; 4-8 parts of lignin sulfonate; and 0.5-2.5 parts of lubricant.

2. The flame-retardant and oil-resistant inner fluoropolymer and outer silicone tubing material according to claim 1, characterized in that, The method for preparing the modified magnesium hydroxide whiskers includes the following steps: (1) Add magnesium hydroxide whiskers to deionized water and adjust the pH to 4-5 with acetic acid. Stir and activate at 50-60°C for 1-2 hours. Filter, wash and dry to obtain pretreated magnesium hydroxide whiskers. (2) Add the pretreated magnesium hydroxide whiskers prepared in step (1) to the solvent, adjust the pH to 5-6 with acetic acid, add silane coupling agent, stir and react at 60-70°C for 2-3h, then add 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt and catalyst, heat to 70-85°C, stir and react for 4-6h, filter, wash and dry, grind and sieve to obtain modified magnesium hydroxide whiskers.

3. The flame-retardant and oil-resistant inner fluoropolymer and outer silicone tubing material according to claim 2, characterized in that, The silane coupling agent mentioned in step (1) is a silane coupling agent containing epoxy groups.

4. The flame-retardant and oil-resistant inner fluoropolymer and outer silicone tubing material according to claim 2, characterized in that, The mass ratio of the pretreated magnesium hydroxide whiskers to the silane coupling agent in step (2) is 1:(0.02-0.06).

5. The flame-retardant and oil-resistant inner fluoropolymer and outer silicone tubing material according to claim 2, characterized in that, The mass ratio of the pretreated magnesium hydroxide whiskers to 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt in step (2) is 1:(0.03-0.08).

6. The flame-retardant and oil-resistant inner fluoropolymer and outer silicone tubing material according to claim 1, characterized in that, The D50 of the polytetrafluoroethylene micropowder is 5-10 μm.

7. The flame-retardant and oil-resistant inner fluoropolymer and outer silicone tubing material according to claim 1, characterized in that, The silicone layer is made from a silicone sheet, which is prepared by compounding flame retardants, methyl vinyl silicone rubber, methyl MQ silicone resin and bis(2,5) vulcanizing agent.

8. The flame-retardant and oil-resistant inner fluoropolymer and outer silicone tubing material according to claim 1, characterized in that, The calendered fabric layer is prepared from calendered fabric, and the method for preparing the calendered fabric includes the following steps: The fumed silica gel is mixed on an open mill for 10-15 minutes, then sheeted with a thickness of 0.1-0.3 mm. After resting, it is re-mixed on the open mill and then calendered at 60-70℃ on a calender to obtain calendered fabric, which is then cut.

9. A method for preparing a flame-retardant and oil-resistant inner fluoropolymer and outer silicone tubing material according to any one of claims 1-8, characterized in that, Includes the following steps: S1. FKM is mixed with carbon black, barium sulfate, modified zinc oxide whiskers, plasticizer, and vulcanization aid on a low-temperature roller to obtain FKM compound; FVMQ is mixed with lignin sulfonate, polytetrafluoroethylene micro powder, and lubricant on a high-temperature roller to obtain FVMQ compound. S2. After the FKM compound and FVMQ compound obtained in step S1 are left to stand, they are added to the internal mixer for mixing; during the mixing process in the internal mixer, the mixture is stretched 5-10 times, and then sheeted on a calender to obtain fluororubber. S3. The fluororubber obtained in step S2 is wound onto a straight mandrel to form an inner fluororubber layer. Calendered fabric is wound onto the surface of the inner fluororubber layer to form a calendered fabric layer. A silicone sheet is wound onto the surface of the calendered fabric layer to form a silicone layer. Finally, a PET film is wound onto the outermost layer to obtain a mandrel-supported tube blank. The thickness of the inner fluororubber layer is 0.1-0.3 mm. S4. Exhaust the mandrel-supported tube blank obtained in step S4 on an exhaust machine. After exhausting, remove the tube blank from the straight mandrel to obtain the tube blank sleeve. S5. Place the tube blank obtained in step S4 onto the mold of the required shape, place it in a vulcanizing tank for vulcanization, remove the obtained tube from the mold after exiting the tank, remove the PET film for secondary vulcanization, clean, cut, inspect, package and store to obtain an inner fluorine outer silicone tube.

10. The method for preparing the flame-retardant and oil-resistant inner fluoropolymer and outer silicone tubing material according to claim 9, characterized in that, The temperature for the first vulcanization in step S5 is 150-175℃ and the time is 30-60 min, while the temperature for the second vulcanization is 180-190℃ and the time is 2-3 h.

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