Highly oxygen-permeable silicone rubber membrane and method for producing the same

Abstract

The application discloses a kind of high oxygen permeability silicone rubber membrane and its preparation method, comprising the following steps: step S1, base material is added to internal mixer, make base material sufficiently plasticized and form uniform continuous phase;Step S2, reinforcing filler is added to the uniform system obtained in step S1, so that reinforcing filler is evenly distributed in base material to form nano reinforcing structure;Step S3, the dispersion obtained in step S2 is cooled, and functional material is added to the dispersion, so that functional material is evenly distributed in base material;Step S4, the rubber obtained in step S3 is placed in an open mill for roll wrapping treatment, crosslinking agent is uniformly dispersed by adding crosslinking agent, and then calendered into a sheet;Step S5, the sheet obtained in step S4 is placed in a hot press, primary vulcanization is carried out, the thickness of the film is controlled, and then secondary vulcanization is carried out to obtain a film product.The preparation method provided by the application can improve the oxygen transfer efficiency, mechanical strength and biocompatibility of the film material.

Description

Technical Field

[0001] This invention relates to the field of membrane materials technology, and in particular to a high oxygen permeability silicone rubber membrane and its preparation method. Background Technology

[0002] Membrane aerated biofilm reactor (MABR) technology is a novel wastewater treatment and water remediation technology that combines membrane aeration and biofilm processes. This technology is applicable to wastewater treatment plant upgrades, advanced nitrogen removal systems for industrial wastewater (including high-ammonia-nitrogen or high-organic-load wastewater from food processing, pharmaceuticals, and chemicals), in-situ remediation systems for polluted rivers and lakes, aquaculture wastewater recycling systems, landfill leachate biological denitrification systems, and decentralized integrated wastewater treatment equipment. It is particularly suitable for wastewater treatment scenarios requiring in-situ expansion, enhanced denitrification, and reduced aeration energy consumption within existing structures.

[0003] MABR technology uses oxygen-permeable hollow fiber membranes as a carrier to achieve bubble-free oxygen supply. Oxygen is transferred to the water outside the membrane through the membrane wall via dissolution-diffusion under a certain pressure (typically 10–50 kPa), without forming bubbles. Microorganisms attach to the outer surface of the hollow fiber membrane and form a biofilm structure. Oxygen diffuses from the inside of the membrane to the outside, while organic pollutants and ammonia nitrogen in the water diffuse back towards the membrane surface, forming a counter-mass transfer structure at the biofilm interface. This enables simultaneous nitrification and denitrification reactions, achieving highly efficient removal of pollutants such as nitrogen and phosphorus. This technology has been applied in the upgrading and renovation of municipal wastewater treatment plants, deep denitrification of industrial wastewater, and ecological restoration of polluted water bodies, and has significant advantages in enhanced denitrification and energy conservation for high-ammonia nitrogen wastewater.

[0004] MABR systems can directly deploy membrane modules within the aerobic zone of traditional activated sludge processes, replacing microporous aeration devices such as aeration discs and aeration pipes, achieving highly efficient oxygen supply without altering the original tank structure. Because oxygen diffuses into the water in molecular form through the membrane wall, avoiding bubble loss, oxygen utilization is significantly improved, and overall system energy consumption is markedly reduced. Therefore, MABR technology is particularly suitable for in-situ expansion and upgrade projects of semi-buried, fully buried, and partially submerged wastewater treatment plants.

[0005] The key to MABR technology lies in the structural design and performance control of oxygen-permeable hollow fiber membrane materials. As a core functional material, the hollow fiber membrane must simultaneously meet the following requirements: it must have a high oxygen permeability coefficient and oxygen transfer rate to ensure sufficient oxygen supply to the inner layer of the biofilm; it must have good mechanical strength and pressure resistance to withstand long-term continuous aeration operation; it must have good biocompatibility to promote rapid attachment and stable growth of microorganisms; and it must have long-term operational stability to avoid material aging and performance degradation.

[0006] Existing membrane materials used in gas transfer and membrane aeration include polyvinylidene fluoride (PVDF), polyether materials, and polydimethylsiloxane (PDMS). Different materials exhibit varying gas transfer mechanisms and performance characteristics. Some membrane materials primarily rely on their microporous structure for gas transfer, which may lead to gas escape, pore fouling, or decreased mass transfer performance during operation. While some hydrophilic polymer materials possess a certain degree of surface hydrophilicity, their gas permeability, mechanical stability, and long-term durability still have room for improvement. Polydimethylsiloxane (PDMS) possesses a flexible silicon-oxygen backbone and high gas permeability. After cross-linking and curing, PDMS forms a three-dimensional network structure. Oxygen can first dissolve in the PDMS material, then diffuse within the membrane material through molecular chain movement, and further transfer to the surrounding water. Therefore, PDMS membrane materials can achieve gas transfer via a dissolution-diffusion mechanism, making them the most promising application material in membrane aeration and gas separation.

[0007] However, existing PDMS membrane materials still have some shortcomings. PDMS material itself is relatively soft, with limited modulus and tensile strength, which may lead to deformation under long-term stress or pressure, affecting the dimensional stability and service life of the membrane material. PDMS surface is highly hydrophobic, which may hinder the initial attachment of microorganisms to the material surface. In complex aquatic environments, the membrane material may also experience surface fouling, aging, or a decline in gas transfer performance during long-term use. Furthermore, improving the oxygen mass transfer rate usually requires reducing the membrane wall thickness, but thinning the membrane wall further reduces mechanical strength, making it difficult to balance oxygen transfer performance with structural stability. Summary of the Invention

[0008] The purpose of this invention is to provide a highly oxygen-permeable silicone rubber membrane and its preparation method, which can improve the oxygen transfer efficiency, mechanical properties and biocompatibility of the membrane material.

[0009] Based on the above problems, the technical solution provided by the present invention is as follows:

[0010] A method for preparing a highly oxygen-permeable silicone rubber membrane includes the following steps:

[0011] Step S1: Add the matrix material to the internal mixer, control the temperature at 80-120℃, and mix for 5-10 minutes to fully plasticize the matrix material and form a uniform and continuous phase;

[0012] Step S2: Add reinforcing filler to the homogeneous system obtained in step S1, and mix at 80-120°C for 30-50 minutes to make the reinforcing filler uniformly distributed in the matrix material to form a nano-reinforcing structure.

[0013] Step S3: Cool the system to 40-60°C, add functional materials to the dispersion obtained in step S2 and mix for 10-30 minutes to ensure that the functional materials are evenly distributed in the matrix material, and then discharge the rubber compound from the internal mixer.

[0014] Step S4: Place the rubber compound obtained in step S3 into a two-roll mill for roll wrapping treatment, add crosslinking agent at 20-25°C and mix for 10-25 minutes to make the crosslinking agent evenly dispersed, and then calender into 500μm thin sheets.

[0015] Step S5: Place the sheet obtained in step S4 into a hot press and perform a first vulcanization at 120-150°C and 15-20MPa for 5-15 minutes, controlling the film thickness to be 100-200μm. Then, perform a second vulcanization at 120-140°C for 1-3 hours to form a stable three-dimensional cross-linked network structure and obtain a film product with high oxygen permeability.

[0016] In some of these embodiments, the matrix material in step S1 is methyl vinyl silicone rubber raw rubber and vinyl polydimethylsiloxane, with a mass ratio of (60-80):(10-30).

[0017] In some embodiments, the number average molecular weight of the methyl vinyl silicone rubber raw rubber is 100,000 to 650,000, and the vinyl content is 0.10 to 0.30 wt%; the vinyl polydimethylsiloxane has a vinyl-terminated structure, a viscosity of 500 to 1500 mPa·s, and a vinyl content of 0.10 to 0.35 wt%. By compounding raw rubber with different molecular weights and vinyl contents with polysiloxane, a wide molecular weight distribution system is constructed, which is beneficial to forming a uniform and stable crosslinking network, thereby improving film-forming performance and mechanical properties while ensuring processing fluidity.

[0018] In some embodiments, the reinforcing filler in step S2 is fumed nano silica, and the mass ratio of the reinforcing filler to the matrix material is (30-60):(70-90). The fumed nano silica forms a nanoscale reinforcing network structure in the matrix, which improves the tensile strength and tear strength of the material. At the same time, by controlling the specific surface area and the degree of surface modification, the free volume distribution inside the silicone rubber is optimized, which enhances the mechanical properties while maintaining or improving the continuity of the oxygen diffusion channels, thereby improving the oxygen permeability.

[0019] In some embodiments, the fumed nano silica is hydrophobic fumed silica that has been surface-modified with hexamethyldisilazane, dimethyldichlorosilane or dimethylsiloxane.

[0020] In some embodiments, the reinforcing material has a specific surface area of ​​150–300 m² / g and a surface carbon content of 0.5–3%.

[0021] In some embodiments, the functional filler in step S3 is one or more of polysilsesquioxane, silicone resin, and diatomaceous earth, and the mass ratio of the functional filler to the matrix material is (5-15):(70-90). The functional filler achieves synergistic regulation of the crosslinked network structure and surface properties of silicone rubber through molecular-scale rigid node construction, micron-scale structural support, and surface hydrophilicity control, thereby improving the biocompatibility of the material while balancing oxygen permeability and mechanical strength.

[0022] In some embodiments, the polysilsesquioxane has the structural formula (RSiO). 1.5 ) n , where R is selected from methyl, vinyl or phenyl.

[0023] In some embodiments, the silicone resin is an MQ type or a T type silicone resin, with an M / Q molar ratio of 0.7 to 1.0; and the diatomaceous earth has a median particle size of 5 to 20 μm.

[0024] In some embodiments, the crosslinking agent in step S4 is platinum water and hydrogen-containing silicone oil. The amount of platinum water is 0.02-0.5% of the matrix mass, and the amount of hydrogen-containing silicone oil is 0.5-4% of the matrix mass. During hot-pressing vulcanization, vinyl groups and Si-H groups undergo an addition reaction under platinum catalysis to form Si-C crosslinking bonds, thereby constructing a uniform and stable three-dimensional crosslinking network structure, which endows the silicone film with good film-forming properties and mechanical strength.

[0025] In some embodiments, the platinum water is a catalyst solution formed by dispersing chloroplatinic acid in a polysiloxane system, with a platinum content of 8000-18000 ppm; the hydrogen-containing silicone oil has a hydrogen-containing structure with end-side groups and a hydrogen content of 0.1-0.5%.

[0026] A highly oxygen-permeable silicone rubber membrane prepared according to any one of the above methods.

[0027] Compared with the prior art, the advantages of the present invention are:

[0028] 1. By introducing organic-inorganic hybrid molecules such as polysilsesquioxane and silicone resin into a silicone rubber matrix, and combining them with a fumed silica nano-reinforcement system, a multi-level composite structure is constructed, consisting of a molecular-scale cross-linked network, nanoscale rigid nodes, and micrometer-scale reinforcing structures. On the one hand, by controlling the intersegmental spacing and free volume distribution of the polysiloxane chains, stable and continuous oxygen diffusion channels are formed, significantly improving the oxygen permeability of the material. On the other hand, through the synergistic reinforcement effect of the hybrid filler and the reinforcing filler, tensile strength and tear strength are improved while maintaining a high elongation at break, achieving synergistic optimization of oxygen permeability and mechanical properties. This solves the technical problem in existing technologies where reinforcing fillers increase strength but reduce oxygen permeability.

[0029] 2. By introducing diatomaceous earth to regulate the microstructure and hydrophilic properties of the film surface, the tendency of protein adsorption on the material surface is reduced, and the compatibility and safety when in contact with aquatic microorganisms are improved. At the same time, a platinum-catalyzed addition-curing sulfurization system is used to form a uniform and stable three-dimensional cross-linked network structure with no by-products generated, high structural stability, and excellent long-term reliability.

[0030] 3. The preparation method has clear process steps, and the temperature, pressure and time parameters are controllable. It is suitable for continuous film formation processes such as calendering or casting, and has good repeatability and industrial scale-up feasibility, which can meet the needs of large-scale production. Detailed Implementation

[0031] The above-described solution will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. The implementation conditions used in the embodiments may be further adjusted according to the conditions of specific manufacturers, and the implementation conditions not specified are generally those in routine experiments.

[0032] Example 1

[0033] A method for preparing a highly oxygen-permeable silicone rubber membrane, comprising the following steps: (The method involves modifying a polysilsesquioxane to obtain a highly oxygen-permeable and tensile-resistant silicone rubber membrane.)

[0034] Step S1: Add 75 parts of methyl vinyl silicone rubber raw rubber and 20 parts of vinyl polydimethylsiloxane to a mixer, heat to 80°C, and mix at this temperature for 10 minutes to fully plasticize the two matrix materials and form a uniform continuous phase.

[0035] Step S2: Add 35 parts of hexamethyldisilazane-modified fumed silica to the mixture obtained in step S1, wherein the fumed silica has a specific surface area of ​​200 m² / g.

[0036] The temperature of the internal mixer is controlled to rise to 100°C, and the mixture is mixed at this temperature for 35 minutes to allow the fumed silica to be uniformly dispersed in the silicone rubber matrix, forming a nanoscale reinforcing structure.

[0037] Step S3: Cool the internal mixer to 50°C, add 7 parts of polysilsesquioxane to the mixing system obtained in step S2, and continue mixing at 50°C for 15 minutes to uniformly disperse the polysilsesquioxane in the rubber compound system to obtain rubber compound A.

[0038] Step S4: Transfer rubber compound A to a two-roll mill, control the mill roll temperature at 25°C, and add platinum solution and hydrogen-containing silicone oil under two-roll conditions for mixing.

[0039] The platinum solution contains 16,000 ppm of platinum, and the amount of platinum solution added is 0.1% of the total mass of the matrix material.

[0040] The hydrogen content in the hydrogen-containing silicone oil is 0.2%, and the amount of hydrogen-containing silicone oil added is 3% of the total mass of the matrix material.

[0041] Mix on a two-roll mill for 20 minutes to ensure the crosslinking agent is evenly dispersed in the rubber compound, thus obtaining rubber compound B.

[0042] Step S5: Place the adhesive material B in a mold for molding and press it into a film with a thickness of 100μm.

[0043] The vulcanization conditions are as follows:

[0044] Molding temperature: 140℃; Molding pressure: 20 MPa; Molding time: 10 minutes.

[0045] After the first vulcanization, the film is transferred to an oven for a second vulcanization, with the temperature controlled at 130℃ and the vulcanization time at 2 hours. After the second vulcanization is completed, it is cooled to room temperature, and the resulting product is a polysilsesquioxane-modified high oxygen-permeable silicone rubber film.

[0046] Example 2

[0047] A method for preparing a highly oxygen-permeable silicone rubber membrane, comprising the following steps:

[0048] Step S1: Add 65 parts of methyl vinyl silicone rubber raw rubber and 10 parts of vinyl polydimethylsiloxane to a mixer, heat to 80°C, and mix at this temperature for 10 minutes to fully plasticize the two matrix materials and form a uniform continuous phase.

[0049] Step S2: Add 45 parts of fumed silica modified with dimethyldichlorosilane to the mixture obtained in step S1. The specific surface area of ​​the fumed silica is 300 m² / g.

[0050] The temperature of the internal mixer is controlled to rise to 100°C, and the mixture is mixed at this temperature for 40 minutes to allow the fumed silica to be uniformly dispersed in the silicone rubber matrix, forming a nanoscale reinforcing structure.

[0051] Step S3: Cool the internal mixer to 50°C, add 10 parts of silicone resin to the mixing system obtained in step S2, and continue mixing at 50°C for 15 minutes to uniformly disperse the silicone resin in the rubber system, thus obtaining rubber compound A.

[0052] Step S4: Transfer rubber compound A to a two-roll mill, control the mill roll temperature at 25°C, and add platinum solution and hydrogen-containing silicone oil under two-roll conditions for mixing.

[0053] The platinum solution contains 10,000 ppm of platinum, and the amount of platinum solution added is 0.2% of the total mass of the matrix material.

[0054] The hydrogen content in the hydrogen-containing silicone oil is 0.1%, and the amount of hydrogen-containing silicone oil added is 1% of the total mass of the matrix material.

[0055] Mix on a two-roll mill for 20 minutes to ensure the crosslinking agent is evenly dispersed in the rubber compound, thus obtaining rubber compound B.

[0056] Step S5: Place the adhesive material B in a mold for molding and press it into a film with a thickness of 100μm.

[0057] The vulcanization conditions are as follows:

[0058] Molding temperature: 140℃; Molding pressure: 20 MPa; Molding time: 10 minutes.

[0059] After the first vulcanization, the film is transferred to an oven for a second vulcanization, with the temperature controlled at 130℃ and the vulcanization time at 2 hours. After the second vulcanization is completed, it is cooled to room temperature, and the resulting product is a silicone resin modified high oxygen permeable silicone rubber film.

[0060] Example 3

[0061] A method for preparing a highly oxygen-permeable silicone rubber membrane, comprising the following steps: [Details of steps would be inserted here]

[0062] Step S1: Add 75 parts of methyl vinyl silicone rubber raw rubber and 10 parts of vinyl polydimethylsiloxane to a mixer, heat to 80°C, and mix at this temperature for 10 minutes to fully plasticize the two matrix materials and form a uniform continuous phase.

[0063] Step S2: Add 50 parts of dimethylsiloxane-modified fumed silica to the mixture obtained in step S1, wherein the fumed silica has a specific surface area of ​​150 m² / g.

[0064] The temperature of the internal mixer is controlled to rise to 100°C, and the mixture is kneaded at this temperature for 45 minutes to allow the fumed silica to be uniformly dispersed in the silicone rubber matrix, forming a nanoscale reinforcing structure.

[0065] Step S3: Cool the internal mixer to 50°C, add 5 parts of diatomaceous earth to the mixing system obtained in step S2, and continue mixing at 50°C for 15 minutes to evenly disperse the diatomaceous earth in the rubber compound system to obtain rubber compound A.

[0066] Step S4: Transfer rubber compound A to a two-roll mill, control the mill roll temperature at 25°C, and add platinum solution and hydrogen-containing silicone oil under two-roll conditions for mixing.

[0067] The platinum solution contains 8000 ppm of platinum, and the amount of platinum solution added is 0.4% of the total mass of the matrix material.

[0068] The hydrogen content in the hydrogen-containing silicone oil is 0.4%, and the amount of hydrogen-containing silicone oil added is 1% of the total mass of the matrix material.

[0069] Mix on a two-roll mill for 20 minutes to ensure the crosslinking agent is evenly dispersed in the rubber compound, thus obtaining rubber compound B.

[0070] Step S5: Place the adhesive material B in a mold for molding and press it into a film with a thickness of 100μm.

[0071] The vulcanization conditions are as follows:

[0072] Molding temperature: 140℃; Molding pressure: 20 MPa; Molding time: 10 minutes.

[0073] After the first vulcanization, the film is transferred to an oven for a second vulcanization, with the temperature controlled at 130℃ and the vulcanization time at 2 hours. After the second vulcanization is completed, it is cooled to room temperature, and the resulting product is a diatomaceous earth modified high oxygen permeable silicone rubber film.

[0074] Example 4

[0075] A method for preparing a highly oxygen-permeable silicone rubber membrane, comprising the following steps: A highly oxygen-permeable and tensile-resistant silicone rubber membrane modified from polysilsesquioxane and silicone resin.

[0076] Step S1: Add 75 parts of methyl vinyl silicone rubber raw rubber and 20 parts of vinyl polydimethylsiloxane to a mixer, heat to 80°C, and mix at this temperature for 10 minutes to fully plasticize the two matrix materials and form a uniform continuous phase.

[0077] Step S2: Add 35 parts of hexamethyldisilazane-modified fumed silica to the mixture obtained in step S1, wherein the fumed silica has a specific surface area of ​​200 m² / g.

[0078] The temperature of the internal mixer is controlled to rise to 100°C, and the mixture is mixed at this temperature for 35 minutes to allow the fumed silica to be uniformly dispersed in the silicone rubber matrix, forming a nanoscale reinforcing structure.

[0079] Step S3: Cool the internal mixer to 50°C, add 5 parts of polysilsesquioxane and 7 parts of silicone resin to the mixing system obtained in step S2, and continue mixing at 50°C for 15 minutes to uniformly disperse the polysilsesquioxane and silicone resin in the rubber compound system to obtain rubber compound A.

[0080] Step S4: Transfer rubber compound A to a two-roll mill, control the mill roll temperature at 25°C, and add platinum solution and hydrogen-containing silicone oil under two-roll conditions for mixing.

[0081] The platinum solution contains 16,000 ppm of platinum, and the amount of platinum solution added is 0.1% of the total mass of the matrix material.

[0082] The hydrogen content in the hydrogen-containing silicone oil is 0.4%, and the amount of hydrogen-containing silicone oil added is 1% of the total mass of the matrix material.

[0083] Mix on a two-roll mill for 20 minutes to ensure the crosslinking agent is evenly dispersed in the rubber compound, thus obtaining rubber compound B.

[0084] Step S5: Place the adhesive material B in a mold for molding and press it into a film with a thickness of 100μm.

[0085] The vulcanization conditions are as follows:

[0086] Molding temperature: 140℃; Molding pressure: 20 MPa; Molding time: 10 minutes.

[0087] After the first vulcanization, the film is transferred to an oven for a second vulcanization, with the temperature controlled at 130℃ and the vulcanization time at 2 hours. After the second vulcanization is completed, it is cooled to room temperature, and the resulting product is a high oxygen permeable silicone rubber film modified by polysilsesquioxane and silicone resin.

[0088] Example 5

[0089] A method for preparing a highly oxygen-permeable silicone rubber membrane, comprising the following steps: The method involves preparing a highly oxygen-permeable and tensile-resistant silicone rubber membrane modified from silicone resin and diatomaceous earth.

[0090] Step S1: Add 75 parts of methyl vinyl silicone rubber raw rubber and 10 parts of vinyl polydimethylsiloxane to a mixer, heat to 80°C, and mix at this temperature for 10 minutes to fully plasticize the two matrix materials and form a uniform continuous phase.

[0091] Step S2: Add 50 parts of dimethyldisiloxane-modified fumed silica to the mixture obtained in step S1, wherein the fumed silica has a specific surface area of ​​150 m² / g.

[0092] The temperature of the internal mixer is controlled to rise to 100°C, and the mixture is kneaded at this temperature for 45 minutes to allow the fumed silica to be uniformly dispersed in the silicone rubber matrix, forming a nanoscale reinforcing structure.

[0093] Step S3: Cool the internal mixer to 50°C, add 7 parts of silicone resin and 5 parts of diatomaceous earth to the mixing system obtained in step S2, and continue mixing at 50°C for 15 minutes to uniformly disperse the silicone resin and diatomaceous earth in the rubber system to obtain rubber compound A.

[0094] Step S4: Transfer rubber compound A to a two-roll mill, control the mill roll temperature at 25°C, and add platinum solution and hydrogen-containing silicone oil under two-roll conditions for mixing.

[0095] The platinum solution contains 10,000 ppm of platinum, and the amount of platinum solution added is 0.2% of the total mass of the matrix material.

[0096] The hydrogen content in the hydrogen-containing silicone oil is 0.2%, and the amount of hydrogen-containing silicone oil added is 3% of the total mass of the matrix material.

[0097] Mix on a two-roll mill for 20 minutes to ensure the crosslinking agent is evenly dispersed in the rubber compound, thus obtaining rubber compound B.

[0098] Step S5: Place the adhesive material B in a mold for molding and press it into a film with a thickness of 100μm.

[0099] The vulcanization conditions are as follows:

[0100] Molding temperature: 140℃; Molding pressure: 20MPa; Molding time: 10 minutes.

[0101] After the first vulcanization, the film is transferred to an oven for a second vulcanization, with the temperature controlled at 130℃ and the vulcanization time at 2 hours. After the second vulcanization is completed, it is cooled to room temperature, and the resulting product is a high oxygen permeable silicone rubber film modified with silicone resin and diatomaceous earth.

[0102] Comparative Example 1

[0103] A silicone rubber film, a basic silicone rubber film prepared from the basic components of the formulation of the present invention, specifically includes the following steps:

[0104] Step S1: Add 85 parts of methyl vinyl silicone rubber raw rubber to a mixer, heat to 80°C, and mix at this temperature for 10 minutes to fully plasticize the matrix material and form a uniform and continuous phase.

[0105] Step S2: Add 35 parts of hexamethyldisilazane-modified fumed silica to the mixture obtained in step S1, wherein the fumed silica has a specific surface area of ​​200 m² / g.

[0106] The temperature of the internal mixer is controlled to rise to 100℃, and the mixture is mixed at this temperature for 35 minutes to allow the fumed silica to be uniformly dispersed in the silicone rubber matrix, forming a nanoscale reinforcing structure, thus obtaining rubber compound A.

[0107] Step S3: Transfer rubber compound A to a two-roll mill, control the mill roll temperature at 25°C, and add platinum solution and hydrogen-containing silicone oil under two-roll conditions for mixing.

[0108] The platinum solution contains 16,000 ppm of platinum, and the amount of platinum solution added is 0.1% of the total mass of the matrix material.

[0109] The hydrogen content in the hydrogen-containing silicone oil is 0.2%, and the amount of hydrogen-containing silicone oil added is 3% of the total mass of the matrix material.

[0110] Mix on a two-roll mill for 20 minutes to ensure the crosslinking agent is evenly dispersed in the rubber compound, thus obtaining rubber compound B.

[0111] Step S4: Place the adhesive material B in a mold for molding and press it into a film with a thickness of 100μm.

[0112] The vulcanization conditions are as follows:

[0113] Molding temperature: 140℃; Molding pressure: 20 MPa; Molding time: 10 minutes.

[0114] After the first vulcanization, the film is transferred to an oven for a second vulcanization, with the temperature controlled at 130°C and the vulcanization time at 2 hours. After the second vulcanization is completed, it is cooled to room temperature, and the resulting product is the silicone rubber film with the basic formula.

[0115] Comparative Example 2

[0116] A silicone rubber film, prepared from commercially available internally mixed rubber, specifically includes the following steps:

[0117] Step S1: Transfer the commercially available internally mixed rubber compound A to a two-roll mill, control the mill roll temperature at 25°C, and add platinum solution and hydrogen-containing silicone oil under two-roll conditions for mixing.

[0118] The platinum solution contains 16,000 ppm of platinum, and the amount of platinum solution added is 0.1% of the total mass of the matrix material.

[0119] The hydrogen content in the hydrogen-containing silicone oil is 0.2%, and the amount of hydrogen-containing silicone oil added is 3% of the total mass of the matrix material.

[0120] Mix on a two-roll mill for 20 minutes to ensure the crosslinking agent is evenly dispersed in the rubber compound, thus obtaining rubber compound B.

[0121] Step S2: Place the adhesive material B in a mold for molding and press it into a film with a thickness of 100μm.

[0122] The vulcanization conditions are as follows:

[0123] Molding temperature: 140℃; Molding pressure: 20 MPa; Molding time: 10 minutes.

[0124] After the first vulcanization, the film is transferred to an oven for a second vulcanization, with the temperature controlled at 130℃ and the vulcanization time at 2 hours. After the second vulcanization is completed, it is cooled to room temperature, and the resulting product is the commercially available silicone rubber film.

[0125] Raw material source:

[0126] (1) Methyl vinyl silicone rubber raw rubber: Hosheng Silicon Industry's 110 raw rubber;

[0127] (2) Vinyl polydimethylsiloxane: Vinyl silicone oil from Hosheng Silicon Industry;

[0128] (3) Fumed silica: Huifu Nanomaterials' hydrophobic series of fumed silica;

[0129] (4) Polysilsesquioxane: Guangzhou Yixin Technology;

[0130] (5) Diatomaceous earth: Merck's Celite diatomaceous earth;

[0131] (6) Hydrogen-containing silicone oil: self-made.

[0132] Performance testing methods:

[0133] (1) Oxygen permeability test: The oxygen permeability coefficient and solubility coefficient of the silicone rubber film were determined using a differential pressure gas permeation instrument (Labthink, VAC-V2) at a test temperature of 25℃;

[0134] (2) Mechanical property testing: Dumbbell-I type specimens were made from silicone rubber film, and the tensile strength, elongation at break and tear strength of the specimens were determined using a universal testing machine (Instron, 3400).

[0135] (3) Surface performance testing: The surface flow potential of the thin film was tested using a solid surface charge meter (Anton Paar, SurPASS 3) with a clamp measuring cell; the hydrophilic and hydrophobic properties of the thin film surface were tested using a contact angle meter (Dataphysics OCA500) with anhydrous ethanol as the test solvent; the surface roughness of the thin film was tested using an atomic force microscope (Bruker, MultiMode8) in Tapping mode.

[0136] (4) Biofilm thickness test: Take domestic sewage (ammonia nitrogen concentration 50mg / L, COD concentration 220mg / L) from the sewage treatment plant and conduct a biofilm adhesion study on the silicone rubber membrane. After 10 days of biofilm attachment, use an optical microscope to test the biofilm thickness in different areas.

[0137] The test data for the above embodiments and comparative examples are shown in Table 1:

[0138] Table 1 Test parameters for silicone rubber membrane

[0139]

[0140] Among the parameters mentioned above, the oxygen permeability coefficient determines the high oxygen permeability of the silicone membrane. The solubility coefficient is a key factor affecting the oxygen permeability coefficient; increasing the solubility coefficient helps enhance oxygen permeability. Tear strength, elongation at break, and tensile strength collectively reflect the mechanical properties of silicone materials. Adjusting the formulation can improve tensile and tear strength, but usually reduces elongation at break; a balance must be struck to obtain optimal mechanical properties. Surface potential, contact angle, surface roughness, and biofilm thickness collectively determine the membrane surface structure and biocompatibility, enabling the silicone membrane to achieve rapid attachment and stable operation.

[0141] As can be seen from the data in the table above, Comparative Example 1 shows improved oxygen permeability and biocompatibility compared to commercially available PDMS membranes (Comparative Example 2). In each example, raw rubber with different molecular weights and vinyl contents was compounded with polysiloxane. Modification with polysilsesquioxane and / or silicone resin can improve the mechanical strength and oxygen permeability of the membrane. Modification with diatomaceous earth can improve the biocompatibility of the membrane. When silicone resin and diatomaceous earth are added simultaneously, the membrane performance is optimal (as in Example 5).

[0142] In summary, by regulating the molecular weight distribution of the organosilicon backbone, the degree of crosslinking of the silicone rubber molecular network is optimized; rigid nodes are constructed at the molecular scale using nano-reinforcing fillers and functional fillers to exert a synergistic reinforcement effect; surface functional fillers are combined to modify the membrane surface potential and micro-roughness; and the crosslinking process is precisely controlled by matching the vulcanizing agent structure. Through the above multi-dimensional synergistic regulation, the oxygen permeability, mechanical strength, and biocompatibility of the material are significantly improved, effectively solving the technical challenge of simultaneously achieving these three aspects in existing technologies.

[0143] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a highly oxygen-permeable silicone rubber membrane, characterized in that, Includes the following steps: Step S1: Add the matrix material to the internal mixer, control the temperature at 80-120℃, mix for a period of time to fully plasticize the matrix material and form a uniform continuous phase. The matrix material is methyl vinyl silicone rubber raw rubber and vinyl polydimethylsiloxane, with a mass ratio of (60-80):(10-30). Step S2: Add reinforcing filler to the homogeneous system obtained in step S1, and mix at 80-120℃ for a period of time to make the reinforcing filler uniformly distributed in the matrix material to form a nano-reinforcing structure. The reinforcing filler is fumed nano-silica, and the mass ratio of the reinforcing filler to the matrix material is (30-60):(70-90). Step S3: Cool the system to 40-60℃, add functional fillers to the dispersion obtained in step S2, and mix for a period of time to ensure the functional fillers are evenly distributed in the matrix material. Then, discharge the compound from the internal mixer. The functional fillers are one or more of polysilsesquioxane, silicone resin, and diatomaceous earth. The mass ratio of the functional fillers to the matrix material is (5-15):(70-90). The polysilsesquioxane has the structural formula (RSiO). 1.5 ) n R is selected from methyl, vinyl, or phenyl; Step S4: Place the rubber compound obtained in step S3 into a two-roll mill for roll wrapping treatment, add a crosslinking agent at 20-25°C and mix for a period of time to make the crosslinking agent evenly dispersed, and then calender into thin sheets. Step S5: Place the sheet obtained in step S4 into a hot press and perform a first vulcanization at 120-150°C and 15-20MPa for 5-15 minutes, controlling the film thickness to be 100-200μm. Then, perform a second vulcanization at 120-140°C for 1-3 hours to form a stable three-dimensional cross-linked network structure and obtain a film product with high oxygen permeability.

2. The method for preparing a high oxygen permeability silicone rubber membrane according to claim 1, characterized in that: The number average molecular weight of the methyl vinyl silicone rubber raw rubber is 100,000 to 650,000, and the vinyl content is 0.10 to 0.30 wt%; the vinyl polydimethylsiloxane has a vinyl-terminated structure, a viscosity of 500 to 1500 mPa·s, and a vinyl content of 0.10 to 0.35 wt%.

3. The method for preparing a high oxygen permeability silicone rubber membrane according to claim 1, characterized in that: The fumed nano silica is a hydrophobic fumed silica that has been surface-modified with hexamethyldisilazane, dimethyldichlorosilane or dimethylsiloxane.

4. The method for preparing a high oxygen permeability silicone rubber membrane according to claim 3, characterized in that: The reinforcing filler has a specific surface area of ​​150–300 m² / g and a surface carbon content of 0.5–3%.

5. The method for preparing a high oxygen permeability silicone rubber membrane according to claim 1, characterized in that: The silicone resin is MQ type or T type silicone resin, and the M / Q molar ratio is 0.7 to 1.0; the median particle size of the diatomaceous earth is 5 to 20 μm.

6. The method for preparing a high oxygen permeability silicone rubber membrane according to claim 1, characterized in that: The crosslinking agents in step S4 are platinum water and hydrogen-containing silicone oil. The amount of platinum water is 0.02 to 0.5% of the matrix mass, and the amount of hydrogen-containing silicone oil is 0.5 to 4% of the matrix mass.

7. The method for preparing a high oxygen permeability silicone rubber membrane according to claim 6, characterized in that: The platinum water is a catalyst solution formed by dispersing chloroplatinic acid in a polysiloxane system, with a platinum content of 8000-18000 ppm; the hydrogen-containing silicone oil has a hydrogen-containing structure at the end side group, with a hydrogen content of 0.1-0.5%.

8. A highly oxygen-permeable silicone rubber membrane prepared by the method according to any one of claims 1 to 7.

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