Low-temperature-resistant low-leakage breathing valve composite diaphragm and preparation method and application thereof

Abstract

The present application relates to the technical field of breathing valve sealing, and discloses a low-temperature-resistant and low-leakage breathing valve composite diaphragm as well as a preparation method and application thereof. The composite diaphragm comprises a polymer sheet layer and a hydrophobic modified fluorosilicone rubber composite material layer, wherein the thickness of the polymer sheet layer is 0.1-1.2 mm; the hydrophobic modified fluorosilicone rubber composite material layer is prepared from a raw material composition containing fluorosilicone rubber, a hydrophobic modifier, inorganic fillers, an acid absorbent, a vulcanizing agent, a release agent and a colorant. The composite diaphragm provided by the present application has a leakage of 0.0010 m 3 / hour at most when used in a breathing valve with a nominal diameter of 150 mm or below at a temperature of 20 DEG C and a 0.75 times opening pressure of a storage tank, and a leakage of 0.0066 m 3 / hour at most when used in a breathing valve with a nominal diameter of 200 mm or above at a temperature of 20 DEG C and a 0.75 times opening pressure of a storage tank, which is superior to the API 2000 standard; meanwhile, the breathing valve does not freeze at a temperature as low as -40 DEG C and can be normally opened.

Description

Technical Field

[0001] This invention relates to the field of breather valve sealing technology, specifically to a low-temperature resistant, low-leakage breather 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 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. 3 The leakage volume is significantly higher than current international standards. Meanwhile, most of China's oil-producing areas are located in high-latitude, high-altitude regions, characterized by large diurnal temperature variations and extremely low winter outdoor temperatures. This makes it easy for the breather valve diaphragm to freeze and fail to open, seriously threatening the production safety of petrochemical storage tank areas. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of traditional breather valve diaphragms being prone to freezing at low temperatures, having high leakage rates, and posing significant safety risks. This invention provides a low-temperature resistant, low-leakage composite diaphragm for breather valves, along with its preparation method and application. The composite diaphragm described in this invention, as a sealing material for tank breather valves, is resistant to low temperatures and exhibits low leakage.

[0005] To achieve the above objectives, the present invention provides a low-temperature resistant, low-leakage breather valve composite diaphragm, the composite diaphragm comprising a polymer sheet layer and a hydrophobic modified fluorosilicone rubber composite material layer.

[0006] The thickness of the polymer sheet is 0.1–1.2 mm.

[0007] The hydrophobic modified fluorosilicone rubber composite material layer is made from a raw material composition containing fluorosilicone rubber, hydrophobic modifier, inorganic filler, acid absorber, vulcanizing agent, release agent and colorant.

[0008] Preferably, the polymer sheet forming the polymer layer is selected from one or more of polyetheretherketone, polytetrafluoroethylene, and polyimide.

[0009] Preferably, in the raw material composition, the fluorosilicone rubber is selected from one or more of FEM26, FEM246 and FEM2802.

[0010] Preferably, in the raw material composition, the hydrophobic modifier is selected from one or more of hexadecyltrimethoxysilane, dimethyldiethoxysilane, and dimethyldichlorosilane.

[0011] Preferably, in the raw material composition, the inorganic filler is selected from one or more of calcium silicate, magnesium silicate, aluminum silicate, calcium carbonate, barium sulfate, diatomaceous earth, and graphite.

[0012] 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.

[0013] Preferably, in the raw material composition, the vulcanizing agent is 2,2-(4-hydroxyphenyl)hexafluoropropane and / or 2,5-dimethyl-2,5-di-tert-butylperoxide.

[0014] Preferably, in the raw material composition, the release agent is selected from one or more of zinc stearate, ammonium stearate, and paraffin wax.

[0015] Preferably, in the raw material composition, the colorant is selected from one or more of iron oxide red, colloidal graphite and carbon black.

[0016] Preferably, in the raw material composition, the weight ratio of the fluorosilicone rubber, the hydrophobic modifier, the inorganic filler, the acid absorber, the vulcanizing agent, the mold release agent, and the colorant is 100:0.2~5:10~40:0.001~15:0.001~5:0.1~2:0.001~3.

[0017] Preferably, the hydrophobic modified fluorosilicone rubber composite material layer further contains a vulcanization accelerator.

[0018] Preferably, the weight ratio of the fluorosilicone rubber to the vulcanization accelerator is 100:0.001 to 2.

[0019] Preferably, the vulcanization accelerator is benzyltriphenylphosphine chloride and / or triallyl isocyanurate.

[0020] Preferably, the thickness ratio of the polymer sheet to the hydrophobic modified fluorosilicone rubber composite layer is 1:1 to 4.

[0021] A second aspect of the present invention provides a method for preparing the low-temperature resistant, low-leakage breather valve composite diaphragm described in the first aspect, the method comprising:

[0022] (1) Hydrophobic modified fluorosilicone rubber composite material: The raw material composition is mixed and then the resulting product is refined multiple times to obtain a hydrophobic modified fluorosilicone rubber composite material.

[0023] (2) Preparation of composite membranes:

[0024] The polymer sheet and the hydrophobic modified fluorosilicone rubber composite material are thermally bonded together and then vulcanized to obtain a composite film.

[0025] 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.

[0026] 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.

[0027] Preferably, in step (2), the conditions for thermal bonding include: a temperature of 150-160°C and a time of 1-10 min.

[0028] Preferably, in step (2), the vulcanization conditions include: a temperature of 180–220°C and a time of 8–24 hours.

[0029] The third aspect of the present invention provides a low-temperature resistant, low-leakage breather valve composite diaphragm prepared by the method described in the second aspect above.

[0030] 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.

[0031] The composite diaphragm provided by the present invention comprises a polymer sheet layer of a specific thickness and a specific hydrophobic modified fluorosilicone rubber composite material layer. The composite diaphragm can delay the freezing time of the breather valve, reduce the adhesion strength of the ice layer, and enable the breather valve to open normally in a low-temperature environment. At the same time, the hydrophobic modified fluorosilicone rubber composite material layer can maintain good elasticity in the leakage range from 0.75 times the opening pressure of the breather valve to below the opening pressure, thereby reducing the leakage of the breather valve.

[0032] Furthermore, the leakage rate of the composite diaphragm provided by this invention at a temperature of 20°C and an opening pressure of 0.75 times that of the tank's breather valve is as follows: for diaphragms with a nominal diameter of 150 mm or less, the leakage rate can be as low as 0.0010 m³ / hour. 3 For diaphragms with a nominal diameter of 200 mm or more, the leakage rate can be as low as 0.0066 m³ / hour. 3 It is superior to the API2000 standard; at the same time, the breathing valve does not freeze and can be opened normally when the temperature is as low as -40℃. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating the preparation of a low-temperature resistant, low-leakage breather valve composite diaphragm as described in this invention. Detailed Implementation

[0034] 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.

[0035] 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.

[0036] The first aspect of this invention provides a low-temperature resistant, low-leakage breather valve composite diaphragm, the composite diaphragm comprising a polymer sheet layer and a hydrophobic modified fluorosilicone rubber composite material layer. The hydrophobic modified fluorosilicone rubber composite material layer is bonded to one side of the polymer sheet layer.

[0037] In this invention, the polymer sheet supports the composite diaphragm, preventing the diaphragm from being too soft and sagging at the edges, which could 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 hydrophobic modified fluorosilicone rubber composite material layer provides the composite diaphragm with hydrophobicity and elasticity. The hydrophobic modification reduces the adhesion of water droplets, thereby avoiding or reducing frost and ensuring that the breather valve can open at low temperatures. Appropriate elastic deformation gives the breather valve excellent sealing performance.

[0038] 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.

[0039] In this invention, the thickness of the polymer sheet is 0.1–1.2 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, 1 mm, 1.1 mm, or 1.2 mm.

[0040] In this invention, the polymer sheet refers to the material that forms 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 forming the polymer sheet layer can be selected from one or more of polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE), and polyimide (PI).

[0041] 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.

[0042] Through research, the inventors discovered that in this invention, the composite membrane composed of a hydrophobic modified fluorosilicone rubber composite material layer prepared from raw materials containing fluorosilicone rubber and hydrophobic modifier, and the polymer sheet layer, as a sealing material for the breather valve, can not only significantly reduce leakage, but also ensure that the breather valve does not freeze at temperatures as low as -40°C.

[0043] In this invention, the hydrophobically modified fluorosilicone rubber composite material layer is prepared from a raw material composition containing fluorosilicone rubber, a hydrophobic modifier, an inorganic filler, an acid absorber, a vulcanizing agent, a release agent, and a colorant. The hydrophobically modified fluorosilicone rubber composite material layer is obtained by mixing, refining, thermally bonding, and vulcanizing the raw material composition.

[0044] In this invention, the fluorosilicone rubber can be any of the types well known to those skilled in the art, as long as it can maintain its rubber form at -40 to -50°C. In a specific embodiment, the fluorosilicone rubber in the raw material composition can be selected from one or more of FEM26, FEM246, and FEM2802.

[0045] According to the present invention, the hydrophobic modifier is used to modify fluorosilicone rubber to delay freezing time, reduce ice adhesion strength, and ensure that the breather valve can open normally in low-temperature environments. In a preferred embodiment, the hydrophobic modifier is selected from one or more of hexadecyltrimethoxysilane, dimethyldiethoxysilane, and dimethyldichlorosilane.

[0046] In this invention, the inorganic filler can be a conventional choice in the art, as long as it can provide adequate filling. 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, further reducing the leakage of the breather valve, and ensuring that the breather valve does not freeze at temperatures as low as -40°C, the inorganic filler in the raw material composition is selected from one or more of calcium silicate, magnesium silicate, aluminum silicate, calcium carbonate, barium sulfate, diatomaceous earth, and graphite.

[0047] In this invention, the acid absorber refers to a medium capable of effectively neutralizing substances such as hydrogen fluoride released during the vulcanization of fluororubber. The acid absorber can be a conventional choice in the art, such as a metal oxide or metal hydroxide, as long as it can neutralize hydrogen fluoride. In a preferred embodiment, the acid absorber in the raw material composition 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 any conventional choice in the art, as long as it enables the fluorosilicone rubber molecules to form a three-dimensional network. In a preferred embodiment, the vulcanizing agent in the raw material composition can be 2,2-(4-hydroxyphenyl)hexafluoropropane and / or 2,5-dimethyl-2,5-di-tert-butylperoxide.

[0049] According to the present 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 low-temperature elastic properties of the hydrophobic modified fluorosilicone rubber composite material layer, thereby reducing the leakage of the breather valve, and ensuring that the breather valve does not freeze when the temperature is as low as -40°C, it is necessary to reasonably control the dosage of the fluorosilicone rubber, the hydrophobic modifier, the inorganic filler, the acid absorbent, the vulcanizing agent, the release agent, and the colorant.

[0052] In a specific embodiment, the weight ratio of the fluorosilicone rubber, the hydrophobic modifier, the inorganic filler, the acid absorber, the vulcanizing agent, the mold release agent, and the colorant in the raw material composition can be 100:0.2-5:10-40:0.001-15:0.001-5:0.1-2:0.001-3, for example 100:5:20:5:3:1:2, 100:3:40: 10:2:0.5:1, 100:2:10:15:1:2:3, 100:4:30:3:5:1.5:0.1, 100:1:10:8:4:0.8:0.5, 100:0.2:25:12:0.1:1.2:2.5, 100:0.5:35:9:2.5:0.1:1.5, 100:3.5:45:13.5:4.5:1.8:2.8.

[0053] In this invention, the addition of a vulcanization accelerator to the raw materials used to prepare the hydrophobic modified fluorosilicone rubber 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 fluorosilicone rubber 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, 100:1, 100:1.2, 100:1.4, 100:1.5, 100:1.6, 100:1.8, or 100:2.

[0054] In this invention, to meet basic usage requirements, the thicknesses of the polymer sheet and the hydrophobic modified fluorosilicone rubber composite material layer need to satisfy a certain relationship. In a specific embodiment, the thickness of the hydrophobic modified fluorosilicone rubber composite material layer is approximately equal to the thickness of the polymer sheet, or the thickness of the hydrophobic modified fluorosilicone rubber composite material layer is slightly thicker than the polymer sheet. In a preferred embodiment, the thickness ratio of the polymer sheet to the hydrophobic modified fluorosilicone rubber composite material 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] A second aspect of the present invention provides a method for preparing the low-temperature resistant, low-leakage breather valve composite diaphragm described above, the method comprising:

[0056] (1) Preparation of hydrophobic modified fluorosilicone rubber composite material: The raw material composition is mixed and then the resulting product is refined multiple times to obtain hydrophobic modified fluorosilicone rubber composite material.

[0057] (2) Preparation of composite membranes:

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

[0059] The method of the present invention first prepares a hydrophobic modified fluorosilicone rubber composite material by mixing and refining, and then thermally bonds and vulcanizes the polymer sheet with the hydrophobic modified fluorosilicone rubber composite material to bond the hydrophobic modified fluorosilicone rubber composite material with the polymer sheet to obtain a composite film including a hydrophobic modified fluorosilicone rubber 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 Guangdong Lina Company LN-300 model mixing machine.

[0061] In the method described in this invention, the refining process can be carried out 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, 120°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 carried out using a Shunfuchang XKJ-480 model mixing mill. In this invention, one refining cycle refers to the rollers rolling over the mixed raw materials once.

[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 conditions can be performed according to conventional practices in the art. To prolong the freezing time of the breather valve, reduce the adhesion strength of the ice layer, ensure the breather valve can open normally in low-temperature environments, and maintain good elasticity of the fluorosilicone rubber in the leakage range above and below the breather valve's opening pressure (0.75 times the opening pressure), thereby reducing the leakage of the breather valve, the vulcanization conditions can be controlled within an appropriate range. In a preferred embodiment, in step (2), the vulcanization temperature is 180–220°C, for example, 180°C, 190°C, 200°C, 210°C, or 220°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 low-temperature resistant, low-leakage breather valve composite diaphragm includes the following steps:

[0065] (1) Preparation of fluorohydrophobic modified fluorosilicone rubber composite material: Fluorosilicone rubber, hydrophobic modifier, inorganic filler, acid absorber, vulcanizing agent, release agent and colorant are mixed. The mixing temperature is 50-80℃, the time is 15-60min, and the rotation speed is 20-60 rpm. The weight ratio of the fluorosilicone rubber, inorganic filler, acid absorber, vulcanizing agent, release agent and colorant is 100:0.2-5:10-40:0.001-15:0.001-5:0.1-2:0.001-3. 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 hydrophobic modified fluorosilicone rubber composite material.

[0066] (2) Preparation of composite membranes:

[0067] The polymer sheet with a thickness of 0.1 to 1.2 mm and the hydrophobic modified fluorosilicone rubber composite material are thermally bonded at a temperature of 150 to 160°C for 1 to 10 minutes, and then vulcanized at a temperature of 180 to 220°C for 8 to 24 hours to obtain a composite film.

[0068] In another specific embodiment, the method for preparing the low-temperature resistant, low-leakage breather valve composite diaphragm includes the following steps:

[0069] (1) Preparation of hydrophobic modified fluorosilicone rubber composite material: Fluorosilicone rubber, hydrophobic modifier, inorganic filler, acid absorber, vulcanizing agent, release agent, colorant and vulcanization accelerator are mixed. The mixing temperature is 50-80℃, the time is 15-60min, and the rotation speed is 20-60 rpm. The weight ratio of the fluorosilicone rubber, inorganic filler, acid absorber, vulcanizing agent, release agent and colorant is 100:0.2-5:10-40:0.001-15:0.001-5:0.1-2:0.001-3. 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 hydrophobic modified fluorosilicone rubber composite material.

[0070] (2) Preparation of composite membranes:

[0071] The polymer sheet with a thickness of 0.1 to 1.2 mm and the hydrophobic modified fluorosilicone rubber composite material are thermally bonded at a temperature of 150 to 160°C for 1 to 10 minutes, and then vulcanized at a temperature of 180 to 220°C for 8 to 24 hours to obtain a composite film.

[0072] The third aspect of the present invention provides a low-temperature resistant, low-leakage breather valve composite diaphragm prepared by the method described in the second aspect above.

[0073] The composite diaphragm prepared by the method described in this invention, when used in breather valves with a nominal diameter of 150 mm or less, exhibits a leakage rate as low as 0.0010–0.0052 m³ at a temperature of 20°C and 0.75 times the opening pressure of the tank breather valve. 3 The composite diaphragm prepared by the method described in this invention, when used in breather valves with a nominal diameter of 200 mm or larger, exhibits a leakage rate as low as 0.0066–0.0296 m³ / s at a temperature of 20°C and 0.75 times the opening pressure of the tank breather valve. 3 In this invention, the "nominal diameter" refers to the nominal diameter of the breather valve connecting flange.

[0074] 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.

[0075] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited thereto.

[0076] In this invention, the leakage amount is measured according to the following method:

[0077] After the composite diaphragms obtained in the following examples and comparative examples were cut and processed, they were left to stand for 24 hours in an environment of 20°C and 60% humidity. Then, they were tested according to the leakage test in SY / T 0511-2010 8.6. The specific process is as follows: the composite diaphragms are installed on the valve discs of breather valves with different nominal diameters. The valve disc counterweight is 1350Pa. The breather valves are then installed on the breather valve test platform. The pressure is adjusted to 1012Pa (0.75 times the opening pressure). The leakage of the breather valve is measured. The value is recorded once every minute for a total of three times. The arithmetic mean is taken as the leakage of the breather valve of the storage tank when the pressure is not lower than 0.75 times the opening pressure (1012Pa).

[0078] In this invention, the all-weather breathing valve low-temperature opening pressure test is performed according to SY / T 0511-2010 8.7, with a test temperature of -40℃ and an input air humidity of 80%.

[0079] In this invention, the fluorosilicone rubbers FEM26, FEM246 and FEM2802 were purchased from Shanghai Sanai New Materials Co., Ltd.

[0080] Example 1

[0081] (1) Preparation of hydrophobically modified fluorosilicone rubber composite material:

[0082] Fluorosilicone rubber (10 kg of fluorosilicone rubber FEM26), hydrophobic modifier (0.5 kg of dimethyldichlorosilane), inorganic filler (4 kg of calcium silicate), acid scavenger (1 kg of calcium oxide), vulcanizing agent (0.2 kg of N,N'-biscinnamaldehyde-1,6-hexanediamine), release agent (0.2 kg of aluminum silicate and 0.2 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 50°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 hydrophobic modified fluorosilicone rubber composite material.

[0083] (2) Preparation of composite membranes:

[0084] The hydrophobic modified fluorosilicone rubber composite material was spread on a 0.1 mm thick PI 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 220 °C for 8 h to obtain a composite film A1 consisting of a 0.2 mm hydrophobic modified fluorosilicone rubber composite material layer and a 0.1 mm PI polymer sheet layer.

[0085] After being left to stand, the composite diaphragm A1 is cut to obtain diaphragm 1a with a nominal diameter of 80 mm, diaphragm 1b with a nominal diameter of 100 mm, diaphragm 1c with a nominal diameter of 150 mm, diaphragm 1d with a nominal diameter of 200 mm, diaphragm 1e with a nominal diameter of 250 mm, and diaphragm 1f with a nominal diameter of 300 mm.

[0086] According to SY / T 0511-2010 8.7, the breathing valve was not frozen and could be opened normally.

[0087] According to SY / T 0511-2010 8.6, the leakage of the above composite diaphragm was tested, and the results are shown in Table 1.

[0088] Table 1

[0089] Composite membrane number Breather valve nominal diameter / mm <![CDATA[Maximum leakage rate m 3 / h]]> 1a 80 0.0016 1b 100 0.0039 1c 150 0.0052 1d 200 0.0085 1e 250 0.0127 1f 300 0.0194

[0090] Example 2

[0091] (1) Preparation of hydrophobically modified fluorosilicone rubber composite material:

[0092] Fluorosilicone rubber (10 kg of fluorosilicone rubber FEM26), hydrophobic modifier (0.02 kg of hexadecyltrimethoxysilane), inorganic filler (0.5 kg of calcium silicate, 0.3 kg of magnesium silicate, and 0.2 kg of graphite), acid scavenger (1.5 kg of magnesium oxide), vulcanizing agent (0.5 kg of 2,2-(4-hydroxyphenyl)hexafluoropropane), release agent (0.01 kg of paraffin wax), colorant (0.2 kg of iron oxide red), and vulcanization accelerator (0.2 kg of benzyltriphenylphosphine chloride) 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 hydrophobic modified fluorosilicone rubber composite material.

[0093] (2) Preparation of composite membranes:

[0094] The hydrophobic modified fluorosilicone rubber composite material was laid on a 0.5 mm thick PEEK polymer sheet and thermally bonded at a temperature of 150 °C for 10 min to obtain a pre-cured composite film. The film was then vulcanized at 180 °C for 24 h to obtain a composite film A2 consisting of a 2 mm hydrophobic modified fluorosilicone rubber composite material layer and a 0.5 mm PEEK polymer sheet layer.

[0095] After being left to stand, the composite diaphragm A2 is cut to obtain diaphragm 2a with a nominal diameter of 80 mm and diaphragm 2b with a nominal diameter of 100 mm and diaphragm 2c with a nominal diameter of 150 mm and diaphragm 2d with a nominal diameter of 200 mm and diaphragm 1e with a nominal diameter of 250 mm and diaphragm 1f with a nominal diameter of 300 mm and diaphragm respectively.

[0096] According to SY / T 0511-2010 8.7, the breathing valve was not frozen and could be opened normally.

[0097] According to SY / T 0511-2010 8.6, the leakage of the above composite diaphragm was tested, and the results are shown in Table 2.

[0098] Table 2

[0099] Composite membrane number Breather valve nominal diameter / mm <![CDATA[Maximum leakage rate m 3 / h]]> 2a 80 0.0012 2b 100 0.0028 2c 150 0.0049 2d 200 0.0072 2e 250 0.0097 2f 300 0.0141

[0100] Example 3

[0101] (1) Preparation of hydrophobically modified fluorosilicone rubber composite material:

[0102] Fluorosilicone rubber (10 kg of fluorosilicone rubber FEM2802), hydrophobic modifier (0.2 kg of dimethyldiethoxysilane), inorganic filler (1 kg of calcium carbonate, 1 kg of diatomaceous earth, 0.5 kg of barium sulfate and 0.1 kg of graphite), acid scavenger (0.5 kg of zinc oxide and 0.5 kg of calcium hydroxide), vulcanizing agent (0.1 kg of 2,2-(4-hydroxyphenyl)hexafluoropropane), release agent (0.01 kg of ammonium stearate), colorant (0.03 kg of iron oxide red), and vulcanization accelerator (0.1 kg of benzyltriphenylphosphine chloride) 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 hydrophobic modified fluorosilicone rubber composite material.

[0103] (2) Preparation of composite membranes:

[0104] The hydrophobic modified fluorosilicone rubber composite material was laid on a 1 mm thick PTFE polymer sheet and thermally bonded at a temperature of 150 °C for 5 min to obtain a pre-cured composite film. The film was then vulcanized at 200 °C for 16 h to obtain a composite film A3 consisting of a 4 mm hydrophobic modified fluorosilicone rubber composite material layer and a 1 mm PTFE polymer sheet layer.

[0105] After being left to stand, the composite diaphragm A3 is cut to obtain diaphragms 3a (nominal diameter 80mm), 3b (nominal diameter 100mm), 3c (nominal diameter 150mm), 3d (nominal diameter 200mm), 3e (nominal diameter 250mm), and 3f (nominal diameter 300mm).

[0106] According to SY / T 0511-2010 8.7, the breathing valve was not frozen and could be opened normally.

[0107] According to SY / T 0511-2010 8.6, the leakage of the above composite diaphragm was tested, and the results are shown in Table 3.

[0108] Table 3

[0109] Composite membrane number Breather valve nominal diameter / mm <![CDATA[Maximum leakage rate m 3 / h]]> 3a 80 0.0018 3b 100 0.0039 3c 150 0.0050 3d 200 0.0091 3e 250 0.0187 3f 300 0.0296

[0110] Example 4

[0111] (1) Preparation of hydrophobically modified fluorosilicone rubber composite material:

[0112] Fluorosilicone rubber (4 kg of fluorosilicone rubber FEM2802 and 6 kg of fluorosilicone rubber FEM26), hydrophobic modifier (0.3 kg of dimethyldichlorosilane), inorganic filler (2 kg of magnesium silicate, 1 kg of calcium carbonate and 0.2 kg of graphite), acid scavenger (0.5 kg of calcium oxide and 0.5 kg of calcium hydroxide), vulcanizing agent (0.01 kg of dicumyl peroxide), release agent (0.1 kg of paraffin wax), colorant (0.2 kg of iron oxide red), and vulcanization accelerator (0.01 kg of triallyl isocyanurate) 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 hydrophobic modified fluorosilicone rubber composite material.

[0113] (2) Preparation of composite membranes:

[0114] The hydrophobic modified fluorosilicone rubber composite material was laid on a 0.6 mm thick PTFE polymer sheet and thermally bonded at a temperature of 160 °C for 6 min to obtain a pre-cured composite film. The film was then vulcanized at 220 °C for 12 h to obtain a composite film A4 consisting of a 0.6 mm hydrophobic modified fluorosilicone rubber composite material layer and a 0.6 mm PTFE polymer sheet layer.

[0115] After being left to stand, the composite diaphragm A4 is cut to obtain diaphragms 4a (nominal diameter 80mm), 4b (nominal diameter 100mm), 4c (nominal diameter 150mm), 4d (nominal diameter 200mm), 4e (nominal diameter 250mm), and 4f (nominal diameter 300mm).

[0116] According to SY / T 0511-2010 8.7, the breathing valve was not frozen and could be opened normally.

[0117] According to SY / T 0511-2010 8.6, the leakage of the above composite diaphragm was tested, and the results are shown in Table 4.

[0118] Table 4

[0119]

[0120]

[0121] Example 5

[0122] (1) Preparation of hydrophobically modified fluorosilicone rubber composite material:

[0123] Fluorosilicone rubber (5 kg of FEM26 and 5 kg of FEM246), hydrophobic modifier (0.5 kg of dimethyldichlorosilane), inorganic fillers (1 kg of calcium silicate, 0.8 kg of magnesium silicate, 0.3 kg of calcium carbonate and 0.2 kg of graphite), acid scavenger (0.8 kg of calcium oxide and 0.4 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 (0.15 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 hydrophobic modified fluorosilicone rubber composite material.

[0124] (2) Preparation of composite membranes:

[0125] The hydrophobic modified fluorosilicone 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 210 °C for 16 h to obtain a composite film A5 consisting of a 1 mm hydrophobic modified fluorosilicone rubber composite material layer and a 0.5 mm PTFE polymer sheet layer.

[0126] After being left to stand, the composite diaphragm A5 is cut to obtain diaphragms 5a (nominal diameter 80mm), 5b (nominal diameter 100mm), 5c (nominal diameter 150mm), 5d (nominal diameter 200mm), 5e (nominal diameter 250mm), and 5f (nominal diameter 300mm).

[0127] According to SY / T 0511-2010 8.7, the breathing valve was not frozen and could be opened normally.

[0128] According to SY / T 0511-2010 8.6, the leakage of the above composite diaphragm was tested, and the results are shown in Table 5.

[0129] Table 5

[0130] Composite membrane number Breather valve nominal diameter / mm <![CDATA[Maximum leakage rate m 3 / h]]> 5a 80 0.0011 5b 100 0.0026 5c 150 0.0050 5d 200 0.0066 5e 250 0.0082 5f 300 0.0111

[0131] Example 6

[0132] The method was implemented according to Example 5, except that the inorganic filler consisted of 1.5 kg of magnesium silicate and 0.8 kg of diatomaceous earth. The specific operation was as follows:

[0133] (1) Preparation of hydrophobically modified fluorosilicone rubber composite material:

[0134] Fluorosilicone rubber (10 kg of fluorosilicone rubber FEM26), hydrophobic modifier (0.5 kg of dimethyl dichlorosilane), inorganic filler (1.5 kg of magnesium silicate and 0.8 kg of diatomaceous earth), acid absorber (0.8 kg of calcium oxide and 0.4 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 (0.15 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 hydrophobic modified fluorosilicone rubber composite material.

[0135] (2) Preparation of composite membranes:

[0136] The hydrophobic modified fluorosilicone rubber composite material was 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 was then vulcanized at 210 °C for 16 h to obtain a composite film A6 consisting of a 1 mm hydrophobic modified fluorosilicone rubber composite material layer and a 0.5 mm PTFE polymer sheet layer.

[0137] After being left to stand, the composite diaphragm A6 is cut to produce diaphragms 6a (nominal diameter 80mm), 6b (nominal diameter 100mm), 6c (nominal diameter 150mm), 6d (nominal diameter 200mm), 6e (nominal diameter 250mm), and 6f (nominal diameter 300mm).

[0138] According to SY / T 0511-2010 8.7, the breathing valve was not frozen and could be opened normally.

[0139] According to SY / T 0511-2010 8.6, the leakage of the above composite diaphragm was tested, and the results are shown in Table 6.

[0140] Table 6

[0141] Composite membrane number Breather valve nominal diameter / mm <![CDATA[Maximum leakage rate m 3 / h]]> 6a 80 0.0014 6b 100 0.0025 5c 150 0.0046 6d 200 0.0094 6e 250 0.0152 6f 300 0.0265

[0142] Example 7

[0143] The method was implemented according to Example 5, except that the inorganic filler was 1 kg of aluminum silicate and 1.3 kg of barium sulfate. The specific operation was as follows:

[0144] Fluorosilicone rubber (10 kg of fluorosilicone rubber FEM246), hydrophobic modifier (0.5 kg of dimethyl dichlorosilane), inorganic filler (1 kg of aluminum silicate and 1.3 kg of barium sulfate), acid scavenger (0.8 kg of calcium oxide and 0.4 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 (0.15 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 hydrophobic modified fluorosilicone rubber composite material.

[0145] (2) Preparation of composite membranes:

[0146] The hydrophobic modified fluorosilicone 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 210 °C for 16 h to obtain a composite film A7 consisting of a 1 mm hydrophobic modified fluorosilicone rubber composite material layer and a 0.5 mm PTFE polymer sheet layer.

[0147] After being left to stand, the composite diaphragm A7 is cut to produce diaphragms 7a (nominal diameter 80mm), 7b (nominal diameter 100mm), 7c (nominal diameter 150mm), 7d (nominal diameter 200mm), 7e (nominal diameter 250mm), and 7f (nominal diameter 300mm).

[0148] According to SY / T 0511-2010 8.7, the breathing valve was not frozen and could be opened normally.

[0149] According to SY / T 0511-2010 8.6, the leakage of the above composite diaphragm was tested, and the results are shown in Table 7.

[0150] Table 7

[0151] Composite membrane number Breather valve nominal diameter / mm <![CDATA[Maximum leakage rate m 3 / h]]> 7a 80 0.0010 7b 100 0.0018 7c 150 0.0041 7d 200 0.0073 7e 250 0.0104 7f 300 0.0170

[0152] Example 8

[0153] The method described in Example 5 was followed, except that no vulcanization accelerator was added. The specific operation was as follows:

[0154] (1) Preparation of hydrophobically modified fluorosilicone rubber composite material:

[0155] Fluorosilicone rubber (10 kg of fluorosilicone rubber FEM246), hydrophobic modifier (0.5 kg of dimethyldichlorosilane), inorganic filler (1 kg of calcium silicate, 0.8 kg of magnesium silicate, 0.3 kg of calcium carbonate and 0.2 kg of graphite), acid scavenger (0.8 kg of calcium oxide and 0.4 kg of calcium hydroxide), vulcanizing agent (0.01 kg of dicumyl peroxide), release agent (0.02 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 hydrophobic modified fluorosilicone rubber composite material.

[0156] (2) Preparation of composite membranes:

[0157] The hydrophobic modified fluorosilicone rubber composite material was 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 was then vulcanized at 210 °C for 16 h to obtain a composite film A8 consisting of a 1 mm hydrophobic modified fluorosilicone rubber composite material layer and a 0.5 mm PTFE polymer sheet layer.

[0158] After being left to stand, the composite diaphragm A8 is cut to produce diaphragms 8a (nominal diameter 80mm), 8b (nominal diameter 100mm), 8c (nominal diameter 150mm), 8d (nominal diameter 200mm), 8e (nominal diameter 250mm), and 8f (nominal diameter 300mm).

[0159] According to SY / T 0511-2010 8.7, the breathing valve was not frozen and could be opened normally.

[0160] According to SY / T 0511-2010 8.6, the leakage of the above composite diaphragm was tested, and the results are shown in Table 8.

[0161] Table 8

[0162] Composite membrane number Breather valve nominal diameter / mm <![CDATA[Maximum leakage rate m 3 / h]]> 8a 80 0.0011 8b 100 0.0027 8c 150 0.0051 8d 200 0.0068 8e 250 0.0097 8f 300 0.0115

[0163] Example 9

[0164] The method described in Example 5 is followed, except that the vulcanization temperature is 190°C. The specific operation is as follows:

[0165] (1) Preparation of hydrophobically modified fluorosilicone rubber composite material:

[0166] Fluorosilicone rubber (10 kg of fluorosilicone rubber FEM246), hydrophobic modifier (0.5 kg of dimethyldichlorosilane), inorganic filler (1 kg of calcium silicate, 0.8 kg of magnesium silicate, 0.3 kg of calcium carbonate and 0.2 kg of graphite), acid scavenger (0.8 kg of calcium oxide and 0.4 kg of calcium hydroxide), vulcanizing agent (0.01 kg of dicumyl peroxide), release agent (0.02 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 hydrophobic modified fluorosilicone rubber composite material.

[0167] (2) Preparation of composite membranes:

[0168] The hydrophobic modified fluorosilicone 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 190 °C for 16 h to obtain a composite film A9 consisting of a 1 mm hydrophobic modified fluorosilicone rubber composite material layer and a 0.5 mm PTFE polymer sheet layer.

[0169] After being left to stand, the composite diaphragm A9 is cut to obtain diaphragms 9a (nominal diameter 80mm), 9b (nominal diameter 100mm), 9c (nominal diameter 150mm), 9d (nominal diameter 200mm), 9e (nominal diameter 250mm), and 9f (nominal diameter 300mm).

[0170] According to SY / T 0511-2010 8.7, the breathing valve was not frozen and could be opened normally.

[0171] According to SY / T 0511-2010 8.6, the leakage of the above composite diaphragm was tested, and the results are shown in Table 9.

[0172] Table 9

[0173]

[0174]

[0175] Example 10

[0176] 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:

[0177] (1) Preparation of hydrophobically modified fluorosilicone rubber composite material:

[0178] Fluorosilicone rubber (10 kg of fluorosilicone rubber FEM246), hydrophobic modifier (0.5 kg of dimethyldichlorosilane), inorganic filler (1 kg of calcium silicate, 0.8 kg of magnesium silicate, 0.3 kg of calcium carbonate and 0.2 kg of graphite), acid scavenger (0.8 kg of calcium oxide and 0.4 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 (0.15 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 hydrophobic modified fluorosilicone rubber composite material.

[0179] (2) Preparation of composite membranes:

[0180] The hydrophobic modified fluorosilicone rubber composite material was laid 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 was then vulcanized at 210 °C for 16 h to obtain a composite film A10 consisting of a 1 mm hydrophobic modified fluorosilicone rubber composite material layer and a 0.8 mm PTFE polymer sheet layer.

[0181] After being left to stand, the composite diaphragm A10 is cut to obtain diaphragms 10a (nominal diameter 80 mm), 10b (nominal diameter 100 mm), 10c (nominal diameter 150 mm), 10d (nominal diameter 200 mm), 10e (nominal diameter 250 mm), and 10f (nominal diameter 300 mm).

[0182] According to SY / T 0511-2010 8.7, the breathing valve was not frozen and could be opened normally.

[0183] According to SY / T 0511-2010 8.6, the leakage of the above composite diaphragm was tested, and the results are shown in Table 10.

[0184] Table 10

[0185] Composite membrane number Breather valve nominal diameter / mm <![CDATA[Maximum leakage rate m 3 / h]]> 10a 80 0.0015 10b 100 0.0023 10c 150 0.0049 10d 200 0.0088 10e 250 0.0139 10f 300 0.0204

[0186] Comparative Example 1

[0187] The method described in Example 5 was followed, except that the thickness of the PTFE polymer sheet was 1.8 mm. The specific operation was as follows:

[0188] (1) Preparation of hydrophobically modified fluorosilicone rubber composite material:

[0189] Fluorosilicone rubber (5 kg of FEM26 and 5 kg of FEM246), hydrophobic modifier (0.5 kg of dimethyldichlorosilane), inorganic fillers (1 kg of calcium silicate, 0.8 kg of magnesium silicate, 0.3 kg of calcium carbonate and 0.2 kg of graphite), acid scavenger (0.8 kg of calcium oxide and 0.4 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 (0.15 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 hydrophobic modified fluorosilicone rubber composite material.

[0190] (2) Preparation of composite membranes:

[0191] The hydrophobic modified fluorosilicone rubber composite material was spread on a 1.8 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 was then vulcanized at 210 °C for 16 h to obtain a composite film B1 consisting of a 1 mm hydrophobic modified fluorosilicone rubber composite material layer and a 1.8 mm PTFE polymer sheet layer.

[0192] After being left to stand, the composite diaphragm B1 is cut to produce diaphragms B1a (nominal diameter 80mm), B1b (nominal diameter 100mm), B1c (nominal diameter 150mm), B1d (nominal diameter 200mm), B1e (nominal diameter 250mm), and B1f (nominal diameter 300mm).

[0193] According to SY / T 0511-2010 8.7, the breathing valve was found to be frozen and could not be opened normally.

[0194] According to SY / T 0511-2010 8.6, the leakage of the above composite diaphragm was tested, and the results are shown in Table 11.

[0195] Table 11

[0196] Composite membrane number Breather valve nominal diameter / mm <![CDATA[Maximum leakage rate m 3 / h]]> B1a 80 0.0972 B1b 100 0.3980 B1c 150 0.8949 B1d 200 0.9800 B1e 250 2.3775 B1f 300 3.9295

[0197] Comparative Example 2

[0198] The method described in Example 5 was followed, except that nitrile rubber (purchased from LG Corporation, Korea, grade LG B3250) was used instead of fluorosilicone rubber. The specific operation was as follows:

[0199] (1) Preparation of hydrophobically modified nitrile rubber composite material:

[0200] Nitrile rubber (10 kg), hydrophobic modifier (0.5 kg dimethyldichlorosilane), inorganic filler (1 kg calcium silicate, 0.8 kg magnesium silicate, 0.3 kg calcium carbonate and 0.2 kg graphite), acid scavenger (0.8 kg calcium oxide and 0.4 kg calcium hydroxide), vulcanizing agent (0.01 kg dicumyl peroxide), vulcanization accelerator (0.01 kg triallyl isocyanurate), release agent (0.02 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 hydrophobic modified nitrile rubber composite material.

[0201] (2) Preparation of composite membranes:

[0202] The hydrophobic modified 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 210 °C for 16 h to obtain a composite film A5 consisting of a 1 mm hydrophobic modified nitrile rubber composite material layer and a 0.5 mm PTFE polymer sheet layer.

[0203] After being left to stand, the composite diaphragm B2 is cut to produce diaphragms B2a (nominal diameter 80mm), B2b (nominal diameter 100mm), B2c (nominal diameter 150mm), B2d (nominal diameter 200mm), B2e (nominal diameter 250mm), and B2f (nominal diameter 300mm).

[0204] According to SY / T 0511-2010 8.7, the breathing valve was found to be frozen and could not be opened normally.

[0205] According to SY / T 0511-2010 8.6, the leakage of the above composite diaphragm was tested, and the results are shown in Table 12.

[0206] Table 12

[0207] Composite membrane number Breather valve nominal diameter / mm <![CDATA[Maximum leakage rate m 3 / h]]> B2a 80 0.0534 B2b 100 0.1255 B2C 150 0.2972 B2d 200 0.7895 B2e 250 1.8750 B2f 300 2.6912

[0208] As can be seen from the results in Table 1-12, the composite diaphragms prepared in Examples 1-10, when used in breather valves with a nominal diameter of 150 mm or less, exhibit leakage rates as low as 0.0010–0.0052 m³ at a temperature of 20°C and 0.75 times the opening pressure of the tank breather valve. 3 Composite diaphragms used in breather valves with a nominal diameter of 200 mm and above exhibit leakage rates as low as 0.0066–0.0296 m³ / s at a temperature of 20°C and an opening pressure of 0.75 times the valve's opening pressure. 3 The breather valve did not freeze and could be opened normally. The composite diaphragms prepared in Comparative Examples 1-2, when used in breather valves with a nominal diameter of 150 mm or less, showed a leakage of 0.0534–0.8949 m³ at 20°C and 0.75 times the opening pressure of the tank breather valve. 3 The composite diaphragm, when used in breather valves with a nominal diameter of 200 mm and above, exhibits a leakage rate of 0.7895–3.9295 m³ / h at a temperature of 20°C and 0.75 times the opening pressure of the tank breather valve. 3 The breathing valve froze and could not open normally. It is evident that the composite diaphragm obtained using the technical solution described in this invention significantly reduces the leakage of the breathing valve from 0.75 times the opening pressure to below the opening pressure, and it is also resistant to low temperatures.

[0209] 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 low-temperature resistant, low-leakage breather valve composite diaphragm, characterized in that, The composite membrane comprises a polymer sheet layer and a hydrophobically modified fluorosilicone rubber composite material layer. The thickness of the polymer sheet is 0.1~1.2 mm; The hydrophobic modified fluorosilicone rubber composite material layer is made from a raw material composition containing fluorosilicone rubber, hydrophobic modifier, inorganic filler, acid absorber, vulcanizing agent, mold release agent and colorant; The polymer sheet forming the polymer layer is selected from one or more of polyetheretherketone, polytetrafluoroethylene, and polyimide; In the raw material composition, the hydrophobic modifier is selected from one or more of hexadecyltrimethoxysilane, dimethyldiethoxysilane, and dimethyldichlorosilane.

2. The composite membrane according to claim 1, characterized in that, In the raw material composition, the fluorosilicone rubber is selected from one or more of FEM26, FEM246 and FEM2802.

3. The composite membrane according to claim 1, characterized in that, In the raw material composition, the inorganic filler is selected from one or more of calcium silicate, magnesium silicate, aluminum silicate, calcium carbonate, barium sulfate, diatomaceous earth, and graphite.

4. The composite membrane according to claim 1 or 2, 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.

5. The composite membrane according to claim 1, characterized in that, In the raw material composition, the vulcanizing agent is 2,2-(4-hydroxyphenyl)hexafluoropropane and / or 2,5-dimethyl-2,5-di-tert-butylperoxide.

6. The composite membrane according to claim 1 or 2, 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.

7. The composite membrane 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.

8. The composite membrane according to claim 1 or 2, characterized in that, In the raw material composition, the weight ratio of the fluorosilicone rubber, the hydrophobic modifier, the inorganic filler, the acid absorber, the vulcanizing agent, the mold release agent, and the colorant is 100:0.2~5:10~40:0.001~15:0.001~5:0.1~2:0.001~3.

9. The composite membrane according to claim 1, characterized in that, The raw material composition also contains a vulcanization accelerator; The weight ratio of the fluorosilicone rubber to the vulcanization accelerator is 100:0.001~2; The vulcanization accelerator is benzyltriphenylphosphine chloride and / or triallyl isocyanurate.

10. The composite membrane according to claim 1, characterized in that, The thickness ratio of the polymer sheet to the hydrophobic modified fluorosilicone rubber composite layer is 1:1 to 4.

11. A method for preparing the low-temperature resistant, low-leakage breather valve composite diaphragm according to any one of claims 1-10, characterized in that, The method includes: (1) Preparation of hydrophobic modified fluorosilicone rubber composite material: The raw material composition is mixed and then the resulting product is refined multiple times to obtain hydrophobic modified fluorosilicone rubber composite material. (2) Preparation of composite membranes: The polymer sheet and the hydrophobic modified fluorosilicone rubber composite material are thermally bonded together and then vulcanized to obtain a composite film.

12. The method according to claim 11, 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.

13. The method according to claim 11 or 12, 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.

14. The method according to claim 11, characterized in that, In step (2), the conditions for thermal bonding include: a temperature of 150~160℃ and a time of 1~10min.

15. The method according to claim 11, characterized in that, In step (2), the vulcanization conditions include a temperature of 180~220℃ and a time of 8~24h.

16. A low-temperature resistant, low-leakage breather valve composite diaphragm prepared by the method according to any one of claims 11-15.

17. The use of the composite diaphragm according to any one of claims 1-10 or the composite diaphragm according to claim 16 as a sealing material for a breather valve.

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