Breathing valve composite diaphragm, its preparation method and application

Abstract

This invention relates to the field of breather valve sealing technology, and discloses a composite diaphragm for breather valves, its preparation method, and its application. The composite diaphragm comprises a polymer sheet layer and a fluororubber composite material layer, wherein the thickness of the polymer sheet layer is 0.1–1 mm; the fluororubber composite material layer is prepared from a raw material composition containing fluororubber, inorganic fillers, chopped fibers, acid absorbers, vulcanizing agents, release agents, and colorants. The leakage rate of the composite diaphragm provided by this invention at a temperature of 20°C and 0.75 times the opening pressure of the breather valve in a storage tank is as follows: for a diaphragm used in a breather valve with a nominal diameter of 150 mm, the leakage rate can be as low as 0.0002 m³ / hour. 3 The diaphragm used in a breather valve with a nominal diameter of 200mm can achieve a leakage rate as low as 0.0011m³ per hour. 3 It is far below the relevant standards for leakage of breather valves at home and abroad, and has excellent high temperature resistance.

Description

Technical Field

[0001] This invention relates to the field of breathing valve sealing technology, specifically to a breathing valve composite diaphragm, its preparation method, and its application. Background Technology

[0002] A breather valve is a valve that ensures the storage tank is isolated from the atmosphere within a certain pressure range, while allowing it to breathe when the pressure exceeds or falls below this range. Its function is to prevent damage to the storage tank due to overpressure or vacuum, and to reduce evaporation losses of the stored medium. Installing a breather valve not only reduces gas emissions from the tank, thus lowering atmospheric pollution, but also prevents damage from overpressure or instability from excessive vacuum, contributing to both safety and environmental protection.

[0003] Currently, domestic research on breather valve design mainly focuses on gas flow above the opening pressure, while the gas leakage rate in the leakage range above and below the opening pressure (0.75 times the opening pressure) has not received sufficient attention. In fact, with the trend towards centralized and large-scale tank farms, this overlooked gas leakage could potentially lead to increased flammable gas concentrations within the tank farm, raising the risk of fire and explosion. Therefore, the American Petroleum Institute (API), in its breather valve standard API Std 2000, clearly stipulates that for breather valves with a nominal diameter less than 150 mm, the maximum leakage rate must not exceed 0.014 m³ / h. 3 For breather valves with a nominal diameter greater than 200mm, the maximum leakage rate per hour must not exceed 0.142m³. 3 The most stringent international standard for leakage control is the standard in some regions (of Germany) that requires breather valves with a nominal diameter of less than 150 mm to have a maximum leakage rate of no more than 0.0017 m³ / hour. 3 For breather valves with a nominal diameter greater than 200mm, the maximum leakage rate per hour must not exceed 0.0045m³. 3 Currently, domestic research and development of breather valves mainly focuses on mechanical structures. However, due to the repeated opening and closing of breather valves during use, coupled with the large amount of corrosive components in oil and gas, mechanical seals are easily damaged and fail, leading to increased leakage. Therefore, a reasonable mechanical structure combined with a high-efficiency sealing rubber diaphragm is necessary to achieve long-term low leakage in breather valves. However, limited by diaphragm materials, my country's breather valve industry standard SY / T0511-2010 stipulates that the maximum leakage rate per hour for breather valves with a nominal diameter of less than 150mm must not exceed 0.04m³. 3 For breather valves with a nominal diameter greater than 200mm, the maximum leakage rate must not exceed 0.4m³ per hour. 3The leakage volume was significantly higher than current international standards. This high leakage volume not only increases the safety risks of my country's petrochemical storage tank areas, posing a significant threat to people's peaceful lives, but also restricts my country's path towards domestically developed petrochemical oil and gas storage solutions. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of high leakage and high safety risks associated with traditional breather valve diaphragms (gaskets) in the prior art, and to provide a composite diaphragm for breather valves, its preparation method, and its application. The composite diaphragm provided by this invention can achieve low leakage in tank breather valves and has excellent high-temperature resistance.

[0005] To achieve the above objectives, the present invention provides a breather valve composite diaphragm, the composite diaphragm comprising a polymer sheet layer and a fluororubber composite material layer, wherein the thickness of the polymer sheet layer is 0.1 to 1 mm; and the fluororubber composite material layer is made from a raw material composition containing fluororubber, inorganic filler, chopped fiber, acid absorber, vulcanizing agent, mold release agent and colorant.

[0006] Preferably, the polymer sheet in the polymer layer is selected from one or more of polyetheretherketone, polytetrafluoroethylene and polyimide.

[0007] Preferably, in the raw material composition, the fluororubber is type 26 fluororubber or type 246 fluororubber.

[0008] Preferably, in the raw material composition, the inorganic filler is selected from one or more of silica, calcium silicate, magnesium silicate, aluminum silicate, calcium carbonate, barium sulfate, diatomaceous earth, graphite, silicon nitride, and boron nitride.

[0009] Preferably, in the raw material composition, the chopped fibers are selected from one or more of aramid fibers, glass fibers, carbon fibers, and ceramic fibers.

[0010] Preferably, the length of the chopped fiber is 1 to 5 mm.

[0011] Preferably, in the raw material composition, the acid absorbent is selected from one or more of magnesium oxide, calcium oxide, zinc oxide and calcium hydroxide.

[0012] Preferably, in the raw material composition, the vulcanizing agent is selected from one or more of N,N'-biscinnamaldehyde-1,6-hexanediamine, 2,2-(4-hydroxyphenyl)hexafluoropropane, dicumyl peroxide and 2,5-dimethyl-2,5-ditert-butylperoxide.

[0013] Preferably, in the raw material composition, the release agent is selected from one or more of zinc stearate, ammonium stearate, and paraffin wax.

[0014] Preferably, in the raw material composition, the colorant is selected from one or more of iron oxide red, colloidal graphite and carbon black.

[0015] Preferably, in the raw material composition, the weight ratio of the fluororubber, the inorganic filler, the chopped fiber, the acid absorber, the vulcanizing agent, the mold release agent and the colorant is 100:10~60:10~30:0.001~20:0.001~5:0.2~2:0.001~3.

[0016] Preferably, the raw material composition further contains a vulcanization accelerator.

[0017] Preferably, the weight ratio of the fluororubber to the vulcanization accelerator is 100:0.001 to 2.

[0018] Preferably, the vulcanization accelerator is benzyltriphenylphosphine chloride and / or triallyl isocyanurate.

[0019] Preferably, the thickness ratio of the polymer sheet to the fluororubber composite layer is 1:1 to 4.

[0020] A second aspect of the present invention provides a method for using the aforementioned breathing valve composite diaphragm, the method comprising:

[0021] (1) Preparation of fluororubber composite material: The raw material composition is mixed and then the resulting product is refined multiple times to obtain fluororubber composite material;

[0022] (2) Preparation of composite membranes:

[0023] The polymer sheet and the fluororubber composite material are thermally bonded together and then vulcanized to obtain a composite film.

[0024] Preferably, in step (1), the mixing conditions include: a temperature of 50-80°C, a time of 15-60 min, and a rotation speed of 20-60 rpm.

[0025] Preferably, in step (1), the refining conditions include: a temperature of 100-140°C, a refining cycle of 10-30 times, and a roller gap of 0.2-4 mm.

[0026] Preferably, in step (2), the conditions for thermal bonding include: a temperature of 150-160°C and a time of 1-10 min.

[0027] Preferably, in step (2), the vulcanization conditions include a temperature of 180–240°C and a time of 8–24 hours.

[0028] A third aspect of the present invention provides a breather valve composite diaphragm prepared by the method described above.

[0029] The fourth aspect of the present invention provides a composite diaphragm as described above, or the application of the composite diaphragm as described above, as a sealing material for a breather valve.

[0030] The composite diaphragm for a breathing valve provided by this invention comprises a polymer sheet layer of a specific thickness and a fluororubber composite material layer of a specific composition. This composite diaphragm has good yield deformation in the leakage range from above 0.75 times the opening pressure of the breathing valve to below the opening pressure, thereby reducing the leakage of the breathing valve. At the same time, the composite diaphragm for a breathing valve provided by this invention has excellent high temperature resistance.

[0031] Furthermore, the leakage rate of the composite diaphragm provided by this invention at a temperature of 20°C and a breather valve opening pressure of 0.75 times is as follows: for a breather valve with a nominal diameter of 150 mm, the leakage rate can be as low as 0.0002 m³ / h. 3 The diaphragm used in a breather valve with a nominal diameter of 200mm can achieve a leakage rate as low as 0.0011m³ per hour. 3 This is far below the relevant standards for leakage of breather valves both domestically and internationally. In this invention, the "nominal diameter" refers to the nominal diameter of the breather valve connecting flange. Attached Figure Description

[0032] Figure 1 This is a flowchart of the preparation of the breathing valve composite diaphragm according to the present invention. Detailed Implementation

[0033] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0034] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0035] A first aspect of the present invention provides a breather valve composite diaphragm, the composite diaphragm comprising a polymer sheet layer and a fluororubber composite material layer. The fluororubber composite material layer is bonded to one side of the polymer sheet layer.

[0036] In this invention, the polymer sheet supports the composite diaphragm, preventing the diaphragm from being too soft and sagging at the edges, which would cause leakage in the breather valve. Lubricants and thermal conductive agents are added during the pretreatment of the polymer sheet, giving it good lubricity, thermal conductivity, and anti-friction properties. The fluororubber composite layer has good elasticity, and appropriate elastic deformation gives the breather valve excellent sealing performance. Combining the polymer sheet and the fluororubber composite layer can significantly reduce the leakage of the breather valve.

[0037] In this invention, the thickness of the polymer sheet should be appropriate. If it is too thick, the membrane will be too hard overall and the surface will be uneven and concave, which will not achieve the effect of reducing the leakage of the breather valve.

[0038] In this invention, the thickness of the polymer sheet is 0.1–1 mm. In specific embodiments, the thickness of the polymer sheet can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1 mm.

[0039] In this invention, the polymer sheet refers to the material forming the polymer sheet layer. In specific embodiments, the polymer sheet forming the polymer sheet layer can be a material well known to those skilled in the art. In a preferred embodiment, the polymer sheet in the polymer sheet layer can be selected from one or more of polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE), and polyimide (PI).

[0040] In a specific embodiment, the polymer sheet is entirely formed of polymer sheet material, and the polymer sheet material needs to be pretreated before use. The pretreatment includes: adding lubricant and thermal conductive agent to enhance its lubricity, thermal conductivity and anti-friction properties, and performing surface treatment on the polymer sheet material.

[0041] Through research, the inventors discovered that, in this invention, a composite membrane composed of a fluororubber composite material layer prepared from a raw material containing fluororubber and the polymer sheet layer, as a sealing material for a breather valve, can significantly reduce leakage.

[0042] In this invention, the fluororubber composite material layer is made from a raw material composition containing fluororubber, inorganic fillers, chopped fibers, acid absorbers, vulcanizing agents, release agents, and colorants. The fluororubber composite material layer is obtained by mixing, refining, thermally bonding, and vulcanizing the raw material composition. Adding chopped fibers to the fluororubber composite material layer helps maintain the dimensional stability of the composite film, increases its deformation recovery ability, and improves its high-temperature resistance.

[0043] In this invention, the fluororubber can be any fluororubber well-known in the art, as long as it can maintain the gasket shape and mechanical strength in oily, acidic, or alkaline environments. In a specific embodiment, the fluororubber in the raw material composition can be type 26 fluororubber and / or type 246 fluororubber.

[0044] In this invention, the inorganic filler can be a conventional choice in the art, as long as it can fill the rubber. In a preferred embodiment, in order to ensure that the diaphragm has good yield deformation in the leakage range above and below the opening pressure of the breather valve, and to further reduce the leakage of the breather valve, the inorganic filler in the raw material composition is selected from one or more of silica, calcium silicate, magnesium silicate, aluminum silicate, calcium carbonate, barium sulfate, diatomaceous earth, graphite, silicon nitride, and boron nitride.

[0045] In the composite membrane described in this invention, the chopped fibers can be various fibers well known to those skilled in the art. In a preferred embodiment, the chopped fibers are selected from one or more of aramid fibers, glass fibers, carbon fibers, and ceramic fibers.

[0046] Specifically, the length of the chopped fibers can be 1 to 5 mm.

[0047] In this invention, the acid absorber refers to an additive capable of absorbing acidic substances released during the preparation of fluororubber composite materials. The acid absorber can be a conventional choice in the art, as long as it can absorb the acidic substances released during the preparation of fluororubber composite materials. In a preferred embodiment, in the raw material composition, the acid absorber is selected from one or more of magnesium oxide, calcium oxide, zinc oxide, and calcium hydroxide.

[0048] In this invention, the vulcanizing agent can be a conventional choice in the art. In a specific embodiment, in the raw material composition, the vulcanizing agent is selected from one or more of N,N'-biscinnamaldehyde-1,6-hexanediamine, 2,2-(4-hydroxyphenyl)hexafluoropropane, dicumyl peroxide, and 2,5-dimethyl-2,5-di-tert-butylperoxide.

[0049] In this invention, the release agent can be a release agent well known to those skilled in the art. In a specific embodiment, in the raw material composition, the release agent is selected from one or more of zinc stearate, ammonium stearate, and paraffin wax.

[0050] In this invention, the colorant can be any colorant well-known to those skilled in the art, as long as it can color the composite film. In a specific embodiment, the colorant in the raw material composition is selected from one or more of iron oxide red, colloidal graphite, and carbon black.

[0051] In this invention, in order to improve the yield recovery performance of the fluororubber composite material layer and thereby reduce the leakage of the breather valve, it is necessary to reasonably control the amount of the fluororubber, the inorganic filler, the acid absorber, the vulcanizing agent, the release agent and the colorant.

[0052] In this invention, in a specific embodiment, the weight ratio of the fluororubber, the inorganic filler, the chopped fiber, the acid absorber, the vulcanizing agent, the mold release agent, and the colorant in the raw material composition can be 100:10~60:0.001~20:0.001~5:0.2~2:0.001~3.

[0053] In this invention, the addition of a vulcanization accelerator to the raw materials used to prepare the fluororubber composite layer is selected according to actual needs. In a specific embodiment, the raw material composition also contains a vulcanization accelerator. In a preferred embodiment, the weight ratio of the fluororubber to the vulcanization accelerator is 100:0.001 to 2, for example, 100:0.001, 100:0.1, 100:0.2, 100:0.5, 100:0.6, 100:0.7, 100:0.8, 100:0.9, or 100:1. Specifically, the vulcanization accelerator is benzyltriphenylphosphine chloride and / or triallyl isocyanurate.

[0054] In this invention, to meet basic usage requirements, the thicknesses of the polymer sheet and the fluororubber composite layer need to satisfy a certain relationship. In specific embodiments, the thickness of the fluororubber composite layer is approximately equal to the thickness of the polymer sheet, or the thickness of the fluororubber composite layer is greater than that of the polymer sheet. In a preferred embodiment, the thickness ratio of the polymer sheet to the fluororubber composite layer is 1:1 to 4, for example, 1:1, 1:1.2, 1:1.4, 1:1.5, 1:1.6, 1:1.8, 1:2, 1:2.2, 1:2.4, 1:2.5, 1:2.6, 1:2.8, 1:3, 1:3.2, 1:3.4, 1:3.6, 1:3.8, or 1:4.

[0055] The second aspect of this invention provides a method for preparing the breathing valve composite diaphragm described in the first aspect, such as... Figure 1 As shown, the method includes:

[0056] (1) Preparation of fluororubber composite material: The raw material composition is mixed and then the resulting product is refined multiple times to obtain fluororubber composite material;

[0057] (2) Preparation of composite membranes:

[0058] The polymer sheet and the fluororubber composite material are thermally bonded together and then vulcanized to obtain a composite film.

[0059] The method of the present invention first prepares fluororubber composite material by mixing and refining, and then thermally bonds and vulcanizes the polymer sheet with the fluororubber composite material to obtain a composite film including a fluororubber composite material layer and a polymer sheet layer.

[0060] In this invention, the mixing process can be performed according to conventional operations in the art. In a preferred embodiment, in step (1), the mixing temperature can be 50–80°C, for example, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C. In a preferred embodiment, in step (1), the mixing time can be 15–60 min, for example, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, or 60 min. In a preferred embodiment, in step (1), the mixing speed can be 20–60 rpm, for example, 20 rpm, 25 rpm, 30 rpm, 35 rpm, 40 rpm, 45 rpm, 50 rpm, 55 rpm, or 60 rpm. In this invention, the mixing is performed using a Baisheng Company BL-6175-B model mixing machine.

[0061] In the method described in this invention, the refining process can be performed according to conventional operations in the art. In a preferred embodiment, in step (1), the refining temperature is 100–140°C, for example, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, or 140°C. In a preferred embodiment, in step (1), the number of refining cycles is 10, 15, 20, 25, or 30. In a preferred embodiment, the roller gap is 0.2–4 mm, for example, 0.2 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, or 4 mm. In this invention, the refining is performed using a Meissen Machinery MRM480 ​​mixing mill. In this invention, one refining cycle refers to the rollers rolling once over the mixed raw material.

[0062] In the method described in this invention, the thermal bonding can be a conventional choice in the art. In a preferred embodiment, in step (2), the thermal bonding temperature is 150–160°C, for example, 150°C, 151°C, 152°C, 153°C, 154°C, 155°C, 156°C, 157°C, 158°C, 159°C, or 160°C. In a preferred embodiment, in step (2), the thermal bonding time is 1–10 min, for example, 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, or 10 min.

[0063] In the method described in this invention, the vulcanization process can be carried out according to conventional operations in the art. To ensure the diaphragm has good yield deformation in the leakage range above and below the breather valve's opening pressure (0.75 times the opening pressure), and to further reduce the breather valve leakage, the vulcanization conditions can be controlled within an appropriate range. In a preferred embodiment, in step (2), the vulcanization temperature can be 180–240°C, for example, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, or 240°C. In a preferred embodiment, in step (2), the vulcanization time is 8–24 hours, for example, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, or 24 hours.

[0064] In one specific embodiment, the method for preparing the breathing valve composite diaphragm includes the following steps:

[0065] (1) Preparation of fluororubber composite material: Fluororubber, inorganic filler, chopped fiber, acid absorber, vulcanizing agent, release agent and colorant are mixed. The mixing temperature is 50-80℃, the mixing time is 15-60min, and the rotation speed is 20-60 rpm. The weight ratio of the fluororubber, inorganic filler, chopped fiber, acid absorber, vulcanizing agent, release agent and colorant is 100:10-60:10-30:0.001-20:0.001-5:0.2-2:0.001-3. Then the obtained product is refined 10-30 times. The refining temperature is 100-140℃ and the roller gap is 0.2-4mm to obtain fluororubber composite material.

[0066] (2) Preparation of composite membranes:

[0067] A polymer sheet with a thickness of 0.1 to 1 mm and the fluororubber composite material are thermally bonded at a temperature of 150 to 160°C for 1 to 10 minutes, followed by vulcanization at a temperature of 180 to 240°C for 8 to 24 hours to obtain a composite film.

[0068] In another specific embodiment, the method for preparing the breathing valve composite diaphragm includes the following steps:

[0069] (1) Preparation of fluororubber composite material: Fluororubber, inorganic filler, chopped fiber, acid absorber, vulcanizing agent, release agent, colorant and vulcanization accelerator are mixed. The mixing temperature is 50-80℃, the mixing time is 15-60min, and the rotation speed is 20-60 rpm. The weight ratio of the fluororubber, inorganic filler, chopped fiber, acid absorber, vulcanizing agent, release agent and colorant is 100:10-60:10-30:0.001-20:0.001-5:0.2-2:0.001-3:0.001-2. Then the obtained product is refined 10-30 times. The refining temperature is 100-140℃ and the roller gap is 0.2-4mm to obtain fluororubber composite material.

[0070] (2) Preparation of composite membranes:

[0071] A polymer sheet with a thickness of 0.1 to 1 mm and the fluororubber composite material are thermally bonded at a temperature of 150 to 160°C for 1 to 10 minutes, followed by vulcanization at a temperature of 180 to 240°C for 8 to 24 hours to obtain a composite film.

[0072] A third aspect of this invention provides a super-breathing valve composite diaphragm prepared by the method described above. The breathing valve composite diaphragm prepared by the method of this invention has low valve leakage and good high-temperature resistance.

[0073] The fourth aspect of the present invention provides the application of the composite diaphragm described in the first aspect or the composite diaphragm described in the third aspect as a sealing material for a breather valve.

[0074] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited thereto.

[0075] In this invention, the fluororubber 246 was purchased from LG Corporation of South Korea and has a density of 1.5 g / cm³. 3 Tensile strength 450 kg / cm 2 The fluororubber 26 was purchased from Shandong Huaxia Shenzhou Company, with a density of 1.8 g / cm³. 3 Tensile strength 135 kg / cm 2 .

[0076] Example 1

[0077] (1) Preparation of fluororubber composite materials:

[0078] Fluororubber (10 kg of fluororubber 246), inorganic filler (6 kg of aluminum silicate), chopped fibers (1 kg of aramid fibers with a length of 1 mm), acid absorber (1 kg of calcium oxide), vulcanizing agent (0.2 kg of N,N'-biscinnamaldehyde-1,6-hexanediamine), release agent (0.02 kg of zinc stearate), and colorant (0.3 kg of colloidal graphite) were added to a mixer and mixed at a speed of 60 rpm, a temperature of 60°C, and a time of 15 min. The resulting product was then refined 10 times with a roller gap of 0.2 mm and a roller temperature of 140°C to obtain a fluororubber composite material.

[0079] (2) Preparation of composite membranes:

[0080] Fluororubber composite material was spread on a 0.1 mm thick PEEK polymer sheet and thermally bonded at a temperature of 160 °C for 1 min to obtain a pre-cured composite film. The film was then vulcanized at 240 °C for 8 h to obtain a composite film A1 consisting of a 0.2 mm fluororubber composite material layer and a 0.1 mm PEEK polymer sheet layer.

[0081] Example 2

[0082] (1) Preparation of fluororubber composite materials:

[0083] Fluororubber (10 kg of fluororubber 26), inorganic fillers (0.5 kg of silica, 0.3 kg of calcium silicate, 0.1 kg of magnesium silicate and 0.1 kg of boron nitride), chopped fibers (1 kg of 5 mm glass fiber and 2 kg of 2 mm carbon fiber), acid absorber (1 kg of magnesium oxide), vulcanizing agent (0.5 kg of N,N'-biscinnamaldehyde-1,6-hexanediamine), release agent (0.02 kg of paraffin wax), and colorant (0.2 kg of iron oxide red) were added to a mixer and mixed at a speed of 20 rpm, a temperature of 80°C, and a time of 60 min. The resulting product was then refined 20 times with a roller gap of 2 mm and a roller temperature of 100°C to obtain a fluororubber composite material.

[0084] (2) Preparation of composite membranes:

[0085] Fluororubber composite material is spread on a 0.5 mm thick PTFE polymer sheet and thermally bonded at a temperature of 150 °C for 10 min to obtain a pre-cured composite film. The film is then vulcanized at 180 °C for 24 h to obtain a composite film A2 consisting of a 2 mm fluororubber composite material layer and a 0.5 mm PTFE polymer sheet layer.

[0086] Example 3

[0087] (1) Preparation of fluororubber composite materials:

[0088] Fluororubber (10 kg of fluororubber 246), inorganic fillers (1 kg of calcium carbonate, 1 kg of diatomaceous earth, 0.5 kg of calcium silicate, and 0.1 kg of graphite), chopped fibers (0.5 kg of 2 mm ceramic fibers and 1.5 kg of 3 mm glass fibers), acid absorber (1 kg of calcium hydroxide), vulcanizing agent (0.02 kg of 2,2-(4-hydroxyphenyl)hexafluoropropane), vulcanization accelerator (0.02 kg of benzyltriphenylphosphine chloride), mold release agent (0.02 kg of ammonium stearate), and colorant (0.03 kg of iron oxide red) were added to a mixer and mixed at a speed of 30 rpm, a temperature of 70°C, and a time of 40 min. The resulting product was then refined 30 times with a roller gap of 4 mm and a roller temperature of 120°C to obtain a fluororubber composite material.

[0089] (2) Preparation of composite membranes:

[0090] Fluororubber composite material is spread on a 1 mm thick PI polymer sheet and thermally bonded at a temperature of 150 °C for 5 min to obtain a pre-cured composite film. The film is then vulcanized at 200 °C for 16 h to obtain a composite film A3 consisting of a 4 mm fluororubber composite material layer and a 1 mm PI polymer sheet layer.

[0091] Example 4

[0092] (1) Preparation of fluororubber composite materials:

[0093] Fluororubber (10 kg of fluororubber 26), inorganic fillers (4 kg of aluminum silicate, 1 kg of barium sulfate, 0.05 kg of silicon nitride and 0.2 kg of graphite), chopped fibers (1 kg of 1 mm aramid fiber and 1 kg of 2 mm glass fiber), acid absorber (1 kg of calcium oxide and 0.5 kg of calcium hydroxide), vulcanizing agent (0.01 kg of dicumyl peroxide), vulcanization accelerator (0.01 kg of triallyl isocyanurate), release agent (0.02 kg of paraffin wax), and colorant (0.2 kg of iron oxide red) were added to a mixer and mixed at a speed of 40 rpm, a temperature of 65°C, and a time of 30 min. The resulting product was then refined 30 times with a roller gap of 0.5 mm and a roller temperature of 130°C to obtain a fluororubber composite material.

[0094] (2) Preparation of composite membranes:

[0095] Fluororubber composite material is laid on a 0.6 mm thick PTFE polymer sheet and thermally bonded at a temperature of 160 °C for 7 min to obtain a pre-cured composite film. The film is then vulcanized at 220 °C for 12 h to obtain a composite film A4 consisting of a 0.6 mm fluororubber composite material layer and a 0.6 mm PTFE polymer sheet layer.

[0096] Example 5

[0097] (1) Preparation of fluororubber composite materials:

[0098] Fluororubber (10 kg of fluororubber 246), inorganic fillers (1 kg of calcium silicate, 1 kg of magnesium silicate, 0.5 kg of calcium carbonate and 0.1 kg of graphite), chopped fibers (1.5 kg of 2 mm aramid fibers), acid absorbent (0.5 kg of calcium oxide and 0.5 kg of calcium hydroxide), vulcanizing agent (0.01 kg of 2,5-dimethyl-2,5-di-tert-butylperoxide), vulcanization accelerator (0.01 kg of triallyl isocyanurate), release agent (0.01 kg of paraffin wax), and colorant (0.15 kg of iron oxide red) were added to a mixer and mixed at a speed of 50 rpm, a temperature of 70°C, and a time of 30 min. The resulting product was then refined 30 times with a roller gap of 1 mm and a roller temperature of 140°C to obtain a fluororubber composite material.

[0099] (2) Preparation of composite membranes:

[0100] Fluororubber composite material is spread on a 0.5 mm thick PTFE polymer sheet and thermally bonded at a temperature of 160 °C for 10 min to obtain a pre-cured composite film. The film is then vulcanized at 240 °C for 16 h to obtain a composite film A5 consisting of a 2 mm fluororubber composite material layer and a 0.5 mm PTFE polymer sheet layer.

[0101] Example 6

[0102] The method was implemented according to Example 5, except that the inorganic filler consisted of 0.5 kg of silica, 1 kg of silicon nitride, and 1.1 kg of boron nitride. The specific operation was as follows:

[0103] (1) Preparation of fluororubber composite materials:

[0104] Fluororubber (10 kg of fluororubber 246), inorganic fillers (0.5 kg of silica, 1 kg of silicon nitride, and 1 kg of boron nitride), chopped fibers (1.5 kg of 2 mm aramid fibers), acid absorber (0.5 kg of calcium oxide and 0.5 kg of calcium hydroxide), vulcanizing agent (0.01 kg of 2,5-dimethyl-2,5-di-tert-butylperoxide), vulcanization accelerator (0.01 kg of triallyl isocyanurate), release agent (0.01 kg of paraffin wax), and colorant (0.15 kg of iron oxide red) were added to a mixer and mixed at a speed of 50 rpm, a temperature of 70°C, and a time of 30 min. The resulting product was then refined 30 times with a roll gap of 1 mm and a roll temperature of 140°C to obtain a fluororubber composite material.

[0105] (2) Preparation of composite membranes:

[0106] Fluororubber composite material is laid on a 0.5 mm thick PTFE polymer sheet and thermally bonded at a temperature of 160 °C for 10 min to obtain a pre-cured composite film. The film is then vulcanized at 240 °C for 16 h to obtain a composite film A6 consisting of a 1 mm fluororubber composite material layer and a 0.5 mm PTFE polymer sheet layer.

[0107] Example 7

[0108] The method was implemented according to Example 5, except that the inorganic filler consisted of 1 kg of aluminum silicate and 1.6 kg of diatomaceous earth. The specific operation was as follows:

[0109] (1) Preparation of fluororubber composite materials:

[0110] Fluororubber (10 kg of fluororubber 246), inorganic fillers (1 kg of aluminum silicate and 1.6 kg of diatomaceous earth), chopped fibers (1.5 kg of 2 mm aramid fibers), acid absorbent (0.5 kg of calcium oxide and 0.5 kg of calcium hydroxide), vulcanizing agent (0.01 kg of 2,5-dimethyl-2,5-di-tert-butylperoxide), vulcanization accelerator (0.01 kg of triallyl isocyanurate), release agent (0.01 kg of paraffin wax), and colorant (0.15 kg of iron oxide red) were added to a mixer and mixed at a speed of 50 rpm, a temperature of 70°C, and a time of 30 min. The resulting product was then refined 30 times with a roller gap of 1 mm and a roller temperature of 140°C to obtain a fluororubber composite material.

[0111] (2) Preparation of composite membranes:

[0112] Fluororubber composite material is spread on a 0.5 mm thick PTFE polymer sheet and thermally bonded at a temperature of 160 °C for 10 min to obtain a pre-cured composite film. The film is then vulcanized at 240 °C for 16 h to obtain a composite film A7 consisting of a 1 mm fluororubber composite material layer and a 0.5 mm PTFE polymer sheet layer.

[0113] Example 8

[0114] The method described in Example 5 was followed, except that no vulcanization accelerator was added. The specific operation was as follows:

[0115] (1) Preparation of fluororubber composite materials:

[0116] Fluororubber (10 kg of fluororubber 246), inorganic fillers (1 kg of calcium silicate, 1 kg of magnesium silicate, 0.5 kg of calcium carbonate and 0.1 kg of graphite), chopped fibers (1.5 kg of 2 mm aramid fibers), acid absorbent (0.5 kg of calcium oxide and 0.5 kg of calcium hydroxide), vulcanizing agent (0.01 kg of 2,5-dimethyl-2,5-di-tert-butylperoxide), release agent (0.01 kg of paraffin wax), and colorant (0.15 kg of iron oxide red) were added to a mixer and mixed at a speed of 50 rpm, a temperature of 70°C, and a time of 30 min. The resulting product was then refined 30 times with a roller gap of 1 mm and a roller temperature of 140°C to obtain a fluororubber composite material.

[0117] (2) Preparation of composite membranes:

[0118] Fluororubber composite material is spread on a 0.5 mm thick PTFE polymer sheet and thermally bonded at a temperature of 160 °C for 10 min to obtain a pre-cured composite film. The film is then vulcanized at 240 °C for 16 h to obtain a composite film A8 consisting of a 1 mm fluororubber composite material layer and a 0.5 mm PTFE polymer sheet layer.

[0119] Example 9

[0120] The method described in Example 5 is followed, except that the vulcanization temperature is 190°C. The specific operation is as follows:

[0121] (1) Preparation of fluororubber composite materials:

[0122] Fluororubber (10 kg of fluororubber 246), inorganic fillers (1 kg of calcium silicate, 1 kg of magnesium silicate, 0.5 kg of calcium carbonate and 0.1 kg of graphite), chopped fibers (1.5 kg of 2 mm aramid fibers), acid absorbent (0.5 kg of calcium oxide and 0.5 kg of calcium hydroxide), vulcanizing agent (0.01 kg of 2,5-dimethyl-2,5-di-tert-butylperoxide), vulcanization accelerator (0.01 kg of triallyl isocyanurate), release agent (0.01 kg of paraffin wax), and colorant (0.15 kg of iron oxide red) were added to a mixer and mixed at a speed of 50 rpm, a temperature of 70°C, and a time of 30 min. The resulting product was then refined 30 times with a roller gap of 1 mm and a roller temperature of 140°C to obtain a fluororubber composite material.

[0123] (2) Preparation of composite membranes:

[0124] Fluororubber composite material is spread on a 0.5 mm thick PTFE polymer sheet and thermally bonded at a temperature of 160 °C for 10 min to obtain a pre-cured composite film. The film is then vulcanized at 190 °C for 16 h to obtain a composite film A9 consisting of a 1 mm fluororubber composite material layer and a 0.5 mm PTFE polymer sheet layer.

[0125] Example 10

[0126] The method described in Example 5 was followed, except that the thickness of the PTFE polymer sheet was 0.8 mm. The specific operation was as follows:

[0127] (1) Preparation of fluororubber composite materials:

[0128] Fluororubber (10 kg of fluororubber 246), inorganic fillers (1 kg of calcium silicate, 1 kg of magnesium silicate, 0.5 kg of calcium carbonate and 0.1 kg of graphite), chopped fibers (1.5 kg of 2 mm aramid fibers), acid absorbent (0.5 kg of calcium oxide and 0.5 kg of calcium hydroxide), vulcanizing agent (0.01 kg of 2,5-dimethyl-2,5-di-tert-butylperoxide), vulcanization accelerator (0.01 kg of triallyl isocyanurate), release agent (0.01 kg of paraffin wax), and colorant (0.15 kg of iron oxide red) were added to a mixer and mixed at a speed of 50 rpm, a temperature of 70°C, and a time of 30 min. The resulting product was then refined 30 times with a roller gap of 1 mm and a roller temperature of 140°C to obtain a fluororubber composite material.

[0129] (2) Preparation of composite membranes:

[0130] Fluororubber composite material is spread on a 0.8 mm thick PTFE polymer sheet and thermally bonded at a temperature of 160 °C for 10 min to obtain a pre-cured composite film. The film is then vulcanized at 240 °C for 16 h to obtain a composite film A10 consisting of a 1 mm fluororubber composite material layer and a 0.8 mm PTFE polymer sheet layer.

[0131] Comparative Example 1

[0132] The method described in Example 5 was followed, except that the thickness of the PTFE polymer sheet was 1.5 mm. The specific operation was as follows:

[0133] (1) Preparation of fluororubber composite materials:

[0134] Fluororubber (10 kg of fluororubber 246), inorganic fillers (1 kg of calcium silicate, 1 kg of magnesium silicate, 0.5 kg of calcium carbonate and 0.1 kg of graphite), chopped fibers (1.5 kg of 2 mm aramid fibers), acid absorbent (0.5 kg of calcium oxide and 0.5 kg of calcium hydroxide), vulcanizing agent (0.01 kg of 2,5-dimethyl-2,5-di-tert-butylperoxide), vulcanization accelerator (0.01 kg of triallyl isocyanurate), release agent (0.01 kg of paraffin wax), and colorant (0.15 kg of iron oxide red) were added to a mixer and mixed at a speed of 50 rpm, a temperature of 70°C, and a time of 30 min. The resulting product was then refined 30 times with a roller gap of 1 mm and a roller temperature of 140°C to obtain a fluororubber composite material.

[0135] (2) Preparation of composite membranes:

[0136] Fluororubber composite material was spread on a 1.5 mm thick PTFE polymer sheet and thermally bonded at a temperature of 160 °C for 10 min to obtain a pre-cured composite film. The film was then vulcanized at 240 °C for 16 h to obtain a composite film B1 consisting of a 2 mm fluororubber composite material layer and a 1.5 mm PTFE polymer sheet layer.

[0137] Comparative Example 2

[0138] The method described in Example 5 was followed, except that nitrile rubber (purchased from LG Corporation, Korea, grade LGB3250) was used instead of fluororubber. The specific operation was as follows:

[0139] (1) Preparation of nitrile rubber composite material:

[0140] Nitrile rubber (10 kg), inorganic fillers (1 kg calcium silicate, 1 kg magnesium silicate, 0.5 kg calcium carbonate and 0.1 kg graphite), chopped fibers (1.5 kg 2 mm aramid fibers), acid absorber (0.5 kg calcium oxide and 0.5 kg calcium hydroxide), vulcanizing agent (0.01 kg 2,5-dimethyl-2,5-di-tert-butylperoxide), vulcanization accelerator (0.01 kg triallyl isocyanurate), mold release agent (0.01 kg paraffin wax), and colorant (0.15 kg iron oxide red) were added to a mixer and mixed at a speed of 50 rpm, a temperature of 70°C, and a time of 30 min. The resulting product was then refined 30 times with a roller gap of 1 mm and a roller temperature of 140°C to obtain a nitrile rubber composite material.

[0141] (2) Preparation of composite membranes:

[0142] The nitrile rubber composite material was laid on a 0.5 mm thick PTFE polymer sheet and thermally bonded at a temperature of 160 °C for 10 min to obtain a pre-cured composite film. The film was then vulcanized at 240 °C for 16 h to obtain a composite film B2 consisting of a 2 mm nitrile rubber composite material layer and a 0.5 mm PTFE polymer sheet layer.

[0143] Comparative Example 3

[0144] The method described in Example 5 was followed, except that short-cut fibers were not added during the preparation of the fluororubber composite material. The specific steps were as follows:

[0145] (1) Preparation of fluororubber composite materials:

[0146] Fluororubber (10 kg of fluororubber 246), inorganic fillers (1 kg of calcium silicate, 1 kg of magnesium silicate, 0.5 kg of calcium carbonate and 0.1 kg of graphite), acid scavenger (0.5 kg of calcium oxide and 0.5 kg of calcium hydroxide), vulcanizing agent (0.01 kg of 2,5-dimethyl-2,5-di-tert-butylperoxide), vulcanization accelerator (0.01 kg of triallyl isocyanurate), release agent (0.01 kg of paraffin wax), and colorant (0.15 kg of iron oxide red) were added to a mixer and mixed at a speed of 50 rpm, a temperature of 70°C, and a time of 30 min. The resulting product was then refined 30 times with a roller gap of 1 mm and a roller temperature of 140°C to obtain a fluororubber composite material.

[0147] (2) Preparation of composite membranes:

[0148] Fluororubber composite material is spread on a 0.5 mm thick PTFE polymer sheet and thermally bonded at a temperature of 160 °C for 10 min to obtain a pre-cured composite film. The film is then vulcanized at 240 °C for 16 h to obtain composite film B3 consisting of a 2 mm fluororubber composite material layer and a 0.5 mm PTFE polymer sheet layer.

[0149] Comparative Example 4

[0150] The method of Example 1 is implemented, except that the fluororubber composite material does not use chopped fibers.

[0151] (1) Preparation of fluororubber composite materials:

[0152] Fluororubber (10 kg of fluororubber 246), inorganic filler (6 kg of aluminum silicate), acid scavenger (1 kg of calcium oxide), vulcanizing agent (0.2 kg of N,N'-biscinnamaldehyde-1,6-hexanediamine), release agent (0.02 kg of zinc stearate), and colorant (0.3 kg of colloidal graphite) were added to a mixer and mixed at a speed of 60 rpm, a temperature of 60°C, and a time of 15 min. The resulting product was then refined 10 times with a roller gap of 0.2 mm and a roller temperature of 140°C to obtain a fluororubber composite material.

[0153] (2) Preparation of composite membranes:

[0154] Fluororubber composite material was laid on a 0.1 mm thick PEEK polymer sheet and thermally bonded at a temperature of 160 °C for 1 min to obtain a pre-cured composite film. The film was then vulcanized at 240 °C for 8 h to obtain a composite film B4 consisting of a 0.2 mm fluororubber composite material layer and a 0.1 mm PEEK polymer sheet layer.

[0155] Test Example 1

[0156] The maximum leakage of the composite materials prepared in the test examples and comparative examples was determined, and the test results are shown in Table 1. The test method was as follows:

[0157] The composite membranes A1-A10 and B1-B4 prepared in the examples and comparative examples were cut after being left to stand to obtain membranes 1a-10a, B1a, B2a, B3a, and B4a that are matched with breathing valves with a nominal diameter of 150 mm, and membranes 1b-10b, B1b, B2b, B3b, and B4b that are matched with breathing valves with a nominal diameter of 200 mm. The tank was left to stand for 24 hours at 20℃ and 60% humidity. The leakage test was conducted according to SY / T0511-2010 8.6. The specific procedure was as follows: the composite diaphragm was installed on the valve disc of the breather valve with different nominal diameters. The valve disc counterweight was 1350Pa. The breather valve was then installed on the breather valve test platform. The pressure was adjusted to 1012Pa (0.75 times the opening pressure). The leakage of the breather valve was measured. The value was recorded once every minute for a total of three times. The arithmetic mean was taken as the leakage of the tank breather valve when the pressure was not lower than 0.75 times the opening pressure (1012Pa).

[0158] Table 1

[0159]

[0160]

[0161] Test Example 2

[0162] The high-temperature resistance of the composite films prepared in Examples 1 and 5 and Comparative Examples 3 and 4 was tested, and the results are shown in Table 2. The high-temperature resistance was determined using the following methods:

[0163] According to GB / T 528-2009, composite films A1 and A5 prepared in Examples 1 and 5, and composite films B3 and B4 prepared in Comparative Examples 3 and 4 were cut into several type 2 dumbbell specimens. The four types of specimens were placed in air ovens at 80℃, 100℃, and 120℃ respectively, and heated continuously for 48 hours, 96 hours, and 168 hours, respectively. Their tensile strength, rate of change of tensile strength, elongation at break, and rate of change of elongation at break were tested.

[0164] Table 2

[0165]

[0166]

[0167] As can be seen from Table 1, the breathing valve composite diaphragm prepared according to the method of the examples has a low leakage rate; in Comparative Example 1, the PTFE polymer sheet is too thick, and the leakage rate of the breathing valve increases significantly; in Comparative Example 2, replacing nitrile rubber with fluororubber significantly increases the leakage rate of the breathing valve; in Comparative Examples 3 and 4, without adding short-cut fibers, the leakage rate of the breathing valve is comparable to that of the examples.

[0168] As can be seen from the results in Table 2, the tensile strength of the composite films prepared in Examples 1 and 5 decreased from a maximum of 11.8 N / mm² during the heating process at temperatures of 80℃ to 120℃ for 48h to 168h. 2 Reduced to a minimum of 10.5 N / mm 2 The tensile strength change rate was 0–11.0%, and the elongation at break increased from 199% to a maximum of 217%, while the elongation at break change rate increased from 0 to a maximum of 11.0%. In Comparative Examples 3 and 4, the composite films prepared underwent heating at 80℃–120℃ for 48–168 hours, with the tensile strength increasing from a maximum of 9.7 N / mm². 2 Reduced to a minimum of 6.3 N / mm 2 The tensile strength variation rate was 1.0%–25.3%, and the elongation at break increased from 234% to a maximum of 292%, with the elongation at break variation rate increasing from 0.4% to a maximum of 25.3%. It is evident that, under high-temperature conditions, the composite membranes prepared in Examples 1 and 5 exhibit higher tensile strength and lower elongation at break than those prepared in Comparative Examples 3 and 4. In other words, the composite membranes prepared in these examples possess better high-temperature resistance than those prepared in Comparative Examples 3 and 4.

[0169] Therefore, the composite diaphragm obtained by using the technical solution described in this invention has a low leakage rate in the breather valve at pressures above 0.75 times the opening pressure and below the opening pressure, and also has excellent high-temperature resistance.

[0170] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A composite diaphragm for a breathing valve, characterized in that, The breather valve composite diaphragm comprises a polymer sheet layer and a fluororubber composite material layer. The thickness of the polymer sheet is 0.1~1mm; The thickness ratio of the polymer sheet to the fluororubber composite layer is 1:1 to 4; The fluororubber composite layer is made from a raw material composition containing fluororubber, inorganic filler, chopped fiber, acid absorber, vulcanizing agent, release agent and colorant.

2. The composite diaphragm for the breathing valve according to claim 1, characterized in that, The polymer sheet forming the polymer layer is selected from one or more of polyetheretherketone, polytetrafluoroethylene, and polyimide.

3. The breathing valve composite diaphragm according to claim 1 or 2, characterized in that, In the raw material composition, the fluororubber is type 26 fluororubber and / or type 246 fluororubber.

4. The composite diaphragm for the breathing valve according to claim 1, characterized in that, In the raw material composition, the inorganic filler is selected from one or more of the following: silica, calcium silicate, magnesium silicate, aluminum silicate, calcium carbonate, barium sulfate, diatomaceous earth, graphite, silicon nitride, and boron nitride.

5. The composite diaphragm for the breathing valve according to claim 1, characterized in that, In the raw material composition, the chopped fibers are selected from one or more of aramid fibers, glass fibers, carbon fibers, and ceramic fibers.

6. The composite diaphragm for the breathing valve according to claim 1, characterized in that, The length of the chopped fibers is 1~5mm.

7. The composite diaphragm for the breathing valve according to claim 1, characterized in that, In the raw material composition, the acid absorbent is selected from one or more of magnesium oxide, calcium oxide, zinc oxide and calcium hydroxide.

8. The composite diaphragm for the breathing valve according to claim 1 or 2, characterized in that, In the raw material composition, the vulcanizing agent is selected from one or more of N,N'-biscinnamaldehyde-1,6-hexanediamine, 2,2-(4-hydroxyphenyl)hexafluoropropane, dicumyl peroxide and 2,5-dimethyl-2,5-ditert-butylperoxide.

9. The composite diaphragm for the breathing valve according to claim 1, characterized in that, In the raw material composition, the release agent is selected from one or more of zinc stearate, ammonium stearate and paraffin wax.

10. The composite diaphragm for the breathing valve according to claim 1, characterized in that, In the raw material composition, the colorant is selected from one or more of iron oxide red, colloidal graphite and carbon black.

11. The breathing valve composite diaphragm according to claim 1 or 2, characterized in that, In the raw material composition, the weight ratio of the fluororubber, the inorganic filler, the chopped fiber, the acid absorber, the vulcanizing agent, the mold release agent and the colorant is 100:10~60:10~30:0.001~20:0.001~5:0.2~2:0.001~3.

12. The composite diaphragm for the breathing valve according to claim 1, characterized in that, The raw material composition also contains a vulcanization accelerator.

13. The composite diaphragm for the breathing valve according to claim 12, characterized in that, The weight ratio of the fluororubber to the vulcanization accelerator is 100:0.001~2.

14. The breathing valve composite diaphragm according to claim 12 or 13, characterized in that, The vulcanization accelerator is benzyltriphenylphosphine chloride and / or triallyl isocyanurate.

15. A method for preparing the breathing valve composite diaphragm according to any one of claims 1-14, characterized in that, The method includes: (1) Preparation of fluororubber composite material: The raw material composition is mixed and then the resulting product is refined multiple times to obtain fluororubber composite material; (2) Preparation of composite membranes: The polymer sheet and the fluororubber composite material are thermally bonded together and then vulcanized to obtain a composite film.

16. The method according to claim 15, characterized in that, In step (1), the mixing conditions include: temperature of 50~80℃, time of 15~60min, and rotation speed of 20~60 rpm.

17. The method according to claim 15 or 16, characterized in that, In step (1), the refining conditions include: a temperature of 100~140℃, a refining cycle of 10~30 times, and a roller gap of 0.2~4mm.

18. The method according to claim 15, characterized in that, In step (2), the conditions for thermal bonding include: a temperature of 150~160℃ and a time of 1~10min.

19. The method according to claim 15, characterized in that, In step (2), the vulcanization conditions include a temperature of 180~240℃ and a time of 8~24h.

20. A breathing valve composite diaphragm prepared by the method according to any one of claims 15-19.

21. The use of the composite diaphragm of the breathing valve according to any one of claims 1-14 or the composite diaphragm of the breathing valve according to claim 20 as a sealing material for a breathing valve.

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