Silicone rubber for use in dirty environments, method of manufacture, articles and uses

Abstract

The application discloses a kind of for dirty environment silicon rubber, preparation method, article and application, the steps of preparation method are as follows: (1) part of methyl vinyl silicone rubber raw rubber is plasticized to obtain plasticized raw rubber; (2) part of methyl vinyl silicone rubber raw rubber, part or all internal lubricant, part of reinforcing filler and part of structure control agent are premixed and heat treated to form a pre-compounded masterbatch with uniform dispersion of lubricant; (3) the plasticized raw rubber, pre-compounded masterbatch, remaining reinforcing filler, antibacterial agent, heat stabilizer and / or antioxidant, vulcanization inhibitor and crosslinking agent are sequentially added and fully mixed to form a uniform rubber compound, obtaining a uniformly mixed rubber compound; (4) the uniformly mixed rubber compound is molded and then subjected to a primary vulcanization reaction; (5) the primary vulcanized product is subjected to a secondary vulcanization reaction. The prepared silicon rubber can be used to prepare O-ring, sealing strip, shower hose or kitchen utensil handle and other products.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a silicone rubber for use in dirty environments, its preparation method, products and applications. Background Technology

[0002] Silicone rubber is widely used in sealing, medical, and kitchen and bathroom applications due to its excellent resistance to high and low temperatures, weather resistance, electrical insulation, and physiological inertness. In bathroom and cleaning appliance scenarios, silicone rubber components (such as O-rings, sealing strips, shower hoses, and handle covers) are often in dynamic contact and immersion states. However, the inherently high coefficient of friction of silicone rubber can lead to problems such as high starting torque, high operating resistance, accelerated wear, increased energy consumption, and a degraded user experience for dynamic seals (such as O-rings and rotary shaft seals).

[0003] Currently, to reduce the coefficient of friction of silicone rubber, the industry typically employs the following methods: First, graphite, molybdenum disulfide, and polytetrafluoroethylene (PTFE) powder can be added as solid lubricants to reduce the coefficient of friction. While this method can reduce the coefficient of friction to some extent, the poor interfacial compatibility between the solid lubricant particles and the silicone rubber matrix, acting as stress concentration points, significantly degrades the material's tensile strength, tear strength, and especially the crucial elastic recovery performance. Furthermore, at high filler levels, the material may even become stiff, losing the core advantages of an elastomer. Simultaneously, this method can lead to material opacity and potentially introduce biocompatibility risks, limiting its application in high-end bathroom and health-related products. Second, low molecular weight silicone oil can also be added as a lubricant to reduce the coefficient of friction; however, these small-molecule lubricants readily migrate from the silicone rubber matrix and precipitate onto the surface. While this provides lubrication in the short term, it is not sustainable, and the precipitated lubricant can contaminate the contact medium (such as water and detergents), potentially affecting subsequent bonding or coating processes. Third, a coating can be applied to the surface of silicone rubber to reduce the coefficient of friction; however, the adhesion between the coating and the silicone rubber substrate is limited, and it is prone to wear and peeling under dynamic friction and immersion in media, resulting in poor durability. In addition, coating processes are usually complex, costly, and difficult to cover all surfaces of complex structural components.

[0004] Furthermore, bathroom and cleaning product environments are typically humid, experience significant temperature fluctuations, and are rich in organic matter, making them highly susceptible to the growth of bacteria, mold, and other microorganisms, impacting hygiene, safety, and user experience. Conventional silicone rubber itself does not possess antibacterial properties and usually requires the addition of antibacterial agents. Commonly used organic antibacterial agents (such as quaternary ammonium salts) or inorganic antibacterial agents (such as silver ions and nano-zinc oxide) typically have weak bonding with the matrix and exist in a physically blended form. These antibacterial agents are prone to gradual migration and loss during the mixing, vulcanization, and long-term use of silicone rubber, resulting in a short antibacterial effective period and potentially leading to biotoxicity or environmental accumulation problems. Physical addition methods can also lead to uneven dispersion of antibacterial agents within the material or decomposition and inactivation under high-temperature processing.

[0005] Therefore, it is essential to develop a silicone rubber with low coefficient of friction, high elastic recovery rate, long-lasting antibacterial properties, and excellent durability, as well as its preparation method. Summary of the Invention

[0006] The purpose of this invention is to provide a silicone rubber, its preparation method, its product, and its application for use in dirty environments.

[0007] To achieve the above objectives, the solution of the present invention is: A method for preparing silicone rubber for use in dirty environments includes the following steps: (1) A portion of methyl vinyl silicone rubber raw rubber is plasticized to obtain plasticized raw rubber; (2) A portion of methyl vinyl silicone rubber raw rubber, a portion or all of the internal lubricant, a portion of the reinforcing filler and all of the structure control agent are premixed and heat-treated to form a pre-composite masterbatch with uniformly dispersed lubricant; wherein the internal lubricant is one of polyether-siloxane macromolecule or fluorinated polyether-siloxane macromolecule; (3) The raw rubber obtained in step (1), the pre-composite masterbatch obtained in step (2), the remaining reinforcing filler, antibacterial agent, heat stabilizer, antioxidant, vulcanization inhibitor and crosslinking agent are added in sequence and then fully mixed to obtain a uniformly mixed rubber compound. (4) After the uniformly mixed rubber compound obtained in step (3) is molded, a vulcanization reaction is carried out. The specific conditions are: the reaction temperature is 160-170℃, the reaction time is 5-15 minutes, and the pressure is variable pressure vulcanization technology; a vulcanized product is obtained. (5) The product obtained in step (4) after one-stage vulcanization is subjected to a two-stage vulcanization reaction. The specific conditions are: treatment at 180-200℃ for 2-4 hours to obtain the silicone rubber for dirty environments.

[0008] Preferably, the polyether-siloxane macromolecule is prepared by reacting vinyl-terminated dimethyl polysiloxane, hydrogen-containing silicone oil, and allyl methoxy polyoxyethylene ether under the catalysis of a platinum catalyst; the fluorinated polyether-siloxane macromolecule can be prepared by reacting diallyl perfluoropolyether, allyl methoxy polyoxyethylene ether, vinyl-terminated dimethyl polysiloxane, and hydrogen-containing silicone oil under the catalysis of a platinum catalyst.

[0009] Preferably, the structuring control agent is one of vinyl hydroxyl silicone oil or hydroxyl silicone oil.

[0010] Preferably, the antibacterial agent is surface-silanized copper-loaded nano-silica.

[0011] Preferably, the reinforcing filler is fumed silica.

[0012] Preferably, the specific conditions for the pressure swing vulcanization technology described in step (4) are: applying a lower pressure in the early stage of vulcanization, and then increasing to the normal vulcanization pressure.

[0013] Preferably, the two-stage vulcanization reaction described in step (5) is carried out in a blower oven.

[0014] The silicone rubber prepared by the aforementioned method for use in dirty environments comprises, by weight, the following components: methyl vinyl silicone rubber raw rubber: 100 parts; reinforcing filler: 20-60 parts; crosslinking agent: 0.5-3 parts; structural control agent: 1-5 parts; internal lubricant: 1-15 parts; antibacterial agent: 0.5-10 parts; heat stabilizer: 0.1-3 parts; antioxidant: 0.1-2 parts; vulcanization inhibitor: 0.01-0.5 parts; wherein the internal lubricant is a polyether-siloxane macromolecule, the molecular structure of which includes a polydimethylsiloxane backbone, polyether segments, and at least one reactive functional group that can be co-vulcanized with the silicone rubber matrix; the antibacterial agent is surface-silanized copper-loaded nano-silica.

[0015] The aforementioned method produces silicone rubber products for use in dirty environments, wherein the products are O-rings, sealing strips, shower hoses, or kitchen utensil handles.

[0016] The aforementioned method is used to prepare silicone rubber for dirty environments in the manufacture of seals or contact parts for bathroom or cleaning products.

[0017] The principle of the method for preparing silicone rubber for dirty environments provided by this invention is as follows: The method for preparing silicone rubber for dirty environments provided by this invention is an improvement on the mature high-temperature vulcanization (HTV) process. It introduces innovative process steps such as pre-composite masterbatch, two-step vulcanization, and pressure swing vulcanization. Through the synergistic effect of these steps, precise control of the microstructure of the material is achieved. Specifically, the method provided by this invention first involves plasticizing raw methyl vinyl silicone rubber in a two-roll mill or internal mixer to reduce molecular chain entanglement and improve processability. Then, a portion or all of the internal lubricant, a portion of the raw methyl vinyl silicone rubber, a portion of the reinforcing filler, and a portion of the structure control agent are premixed, heat-treated, and thoroughly sheared to form a pre-composite masterbatch with uniformly dispersed lubricant. This step aims to address the compatibility issue between the lubricant and the matrix in advance, ensuring no agglomerates in the final compound. The internal lubricant, polyether-siloxane, contains both polydimethylsiloxane segments compatible with the silicone rubber matrix and hydrophilic lubricating polyether segments, while also retaining unreacted vinyl groups. This allows it to be well-compatible with the matrix and participate in the crosslinking reaction during vulcanization through vinyl groups. Next, the remaining components are added sequentially and thoroughly mixed to form a homogeneous compound. The mixing process employs programmed temperature control and applies high shear force at specific stages to ensure thorough dispersion of each functional component. Finally, a vulcanization reaction is carried out to remove volatile small molecules, promoting the improvement of the silicone rubber network structure and the firm fixation of functional components. In one stage of the vulcanization process, pressure swing vulcanization technology can be used: a lower pressure (e.g., 3-8 MPa) is applied in the early stage of vulcanization (e.g., the first 2 minutes), and then the pressure is increased to the normal vulcanization pressure (e.g., 10-15 MPa). This technology helps to guide the lubricating components to accumulate in the surface area of ​​the matrix, forming a lubricating functional gradient material, thereby achieving the effect of "external smoothness and internal toughness".

[0018] The advantages of the silicone rubber for dirty environments and the preparation method thereof provided by this invention are as follows: 1. The method for preparing silicone rubber for dirty environments provided by the present invention uses an internal lubricant with reactive functional groups, which is chemically bonded to form part of the crosslinked network of silicone rubber during the vulcanization process. This not only provides a durable and stable low coefficient of friction (e.g., the coefficient of friction can be as low as 0.31, and after 10,000 cycles of reciprocating friction, the coefficient of friction remains stable at 0.32), but also maximizes the preservation of the inherent high elastic recovery rate of silicone rubber (e.g., the elongation at break can be maintained above 700%). It successfully solves the core contradiction of the degradation of elastic and other mechanical properties caused by traditional solid lubricants.

[0019] 2. The method for preparing silicone rubber for dirty environments provided by this invention uses surface-silanized copper-loaded nano-silica as an antibacterial agent. After hydrolysis of its silanoxy groups, it can form strong Si-O-Si covalent bonds with reinforcing fillers (fumed silica) or silicone rubber chains, effectively "locking" the antibacterial cationic centers within the rubber network. The antibacterial components do not migrate out, achieving long-lasting antibacterial effects (e.g., antibacterial rate >99%), while avoiding performance degradation and potential safety risks caused by antibacterial agent loss.

[0020] 3. The silicone rubber prepared by this invention for use in dirty environments not only has stable mechanical and frictional properties over a long period of time, but also has excellent water resistance, chemical resistance (such as detergents), heat resistance (such as hot water), and aging resistance. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to embodiments. It should also be understood that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. The specific mass, reaction time, temperature, process parameters, etc., in the examples are merely examples within a suitable range. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention.

[0022] Unless otherwise specified, all reagents used are commercially available and were not further purified before use.

[0023] The synthesis steps of the polyether-siloxane macromolecular internal lubricant used in some embodiments of the present invention are as follows: (1) Add 100g of vinyl-terminated dimethyl polysiloxane (molecular weight approximately 50,000, vinyl content 0.15 mol%), 8g of 202 hydrogen-containing silicone oil (hydrogen content 0.5%), 30g of allyl methoxy polyoxyethylene ether (molecular weight approximately 1000) and 150ml of toluene to a dry four-necked flask equipped with a stirrer, thermometer, condenser and nitrogen inlet tube. Then turn on the nitrogen and slowly ventilate for 20 minutes to replace the air in the reaction flask and maintain a slight positive nitrogen pressure. Add approximately 0.06g of Karstedt platinum catalyst (platinum concentration 3%) while stirring. (2) The reaction system was slowly heated to 90°C and the reaction was continued at this temperature for 7 hours. The heating was then stopped and the reaction solution was cooled to room temperature. The solvent toluene was removed by vacuum distillation in a rotary evaporator at a water bath temperature of 85°C to obtain a pale yellow, viscous liquid product, which is the polyether-siloxane macromolecular internal lubricant. The obtained lubricant is named Lub-1.

[0024] The synthesis steps of the fluorinated polyether-siloxane macromolecular internal lubricant used in some embodiments of the present invention are as follows: (1) Add 100g of vinyl-terminated dimethyl polysiloxane (molecular weight approximately 50,000, vinyl content 0.15 mol%), 10g of 202 hydrogen-containing silicone oil (hydrogen content 0.5%), 20g of allyl methoxy polyoxyethylene ether (molecular weight approximately 1000), 150ml of toluene and 30ml of trifluorotoluene to a dry four-necked flask equipped with a stirrer, thermometer, condenser and nitrogen inlet tube. Then turn on the nitrogen and slowly ventilate for 20 minutes to replace the air in the reaction flask and maintain a slight positive nitrogen pressure. Add approximately 0.06g of Karstedt platinum catalyst (platinum concentration 3%) while stirring. (2) Slowly heat the reaction system to 95°C and continue the reaction at this temperature for 2 hours. Then, slowly add 20g of dielyl perfluoropolyether (there is no commercial product on the market, so it needs to be made in-house) into the reaction flask through a constant pressure dropping funnel over 30 minutes. Continue the reaction of the resulting mixture at 95°C for about 4.5 hours and then stop heating. Cool the reaction solution to room temperature. Use a rotary evaporator to distill under reduced pressure at a water bath temperature of 90°C. The resulting slightly yellow transparent viscous liquid after removing the solvent is the internal lubricant of the fluorinated polyether-siloxane macromolecule. The obtained lubricant is named Lub-2.

[0025] The specific preparation steps for homemade dielyl perfluoropolyether are as follows: Under nitrogen protection, add 200 ml of anhydrous THF to a dry three-necked flask. Then, cool the THF to 0°C in an ice bath. Slowly add 4 g of NaH (60% dispersion, containing approximately 2.4 g of pure NaH, 0.1 mol, added in 4 batches of 1 g each). Continue stirring the resulting mixture at 0°C for 15 minutes. Slowly add 50 g of perfluoropolyether glycol (preheated to 40°C to reduce viscosity), controlling the dropping rate at 2-3 drops / second. After the addition is complete, remove the ice bath, allow it to warm naturally to room temperature, and continue stirring for 1 hour until no bubbles are generated (sodium alkoxide is completely formed) and the solution becomes clear. Add 14 g of allyl bromide and 20 ml of... After mixing with THF, the mixture was slowly added dropwise to a three-necked flask through a constant-pressure dropping funnel. After the addition was complete, the mixture was stirred at room temperature for 2 hours, then heated to 40°C and stirred for another 6 hours. The three-necked flask was then placed in an ice bath to cool to 0°C. 50 ml of anhydrous methanol was slowly added dropwise to the three-necked flask (in 5 batches of 10 ml each) to quench unreacted NaH. Then, 100 ml of saturated sodium chloride solution was added dropwise, and the mixture was stirred for 15 minutes. After standing, the reaction solution was transferred to a separatory funnel and washed with 100 ml of n-hexane at least twice. The lower layer of perfluoropolyether phase was collected. 20 g of anhydrous sodium sulfate was added to the obtained perfluoropolyether phase, and the mixture was dried for 30 minutes before filtration. The filtrate was then rotary evaporated at 45°C for 2 hours to obtain a pale yellow transparent oil, which is diallyl perfluoropolyether.

[0026] The synthesis steps of the antibacterial agents used in some embodiments of the present invention are as follows: (1) 2.5 g of carbon microspheres (particle size between 5 and 30 micrometers) were added to 90 ml of 1 mol / L hydrochloric acid solution and stirred until homogeneous. Then, 4.25 g of tetraethyl orthosilicate was slowly added, followed by 75 ml of ethanol solution containing 0.91 g of copper acetate. The resulting mixture was stirred at room temperature for 2 hours to obtain a silica sol containing copper ions. The obtained sol was transferred to a microwave reactor for thermal aging treatment: the microwave reaction was carried out for 1.5 hours at a microwave power of 350 W and a temperature of 60 °C. After the reaction was completed, the mixture was allowed to cool to room temperature and then separated by centrifugation. The resulting solid was washed sequentially with 30 ml of water, 30 ml of a water-methanol mixture (volume ratio 1:1), 30 ml of methanol, and 30 ml of acetone. After washing, the solid was vacuum dried overnight at 60 °C. Subsequently, the dried solid powder was evenly spread in a corundum crucible and then placed in a microwave sintering furnace. The microwave power was set to 1200 W, and the mixture was sintered in air at 450°C for 30 minutes to obtain copper-loaded nano-silica. (2) Disperse 2g of copper-loaded nano-silica powder obtained in step (2) in 50 mL of anhydrous ethanol, sonicate for 30 minutes, add 0.12 g of vinyltrimethoxysilane to the resulting suspension, and then reflux the resulting mixture at 80°C for 4 hours under nitrogen protection. After the reaction, centrifuge and wash the resulting solid three times with anhydrous ethanol. Place the washed solid in a vacuum drying oven and dry at 80°C for 12 hours to obtain surface-silanized copper-loaded nano-silica. Add 0.1 g of the prepared surface-silanized copper-loaded nano-silica to 10 g of epoxy resin, sonicate and let stand for 24 hours without sedimentation, indicating that it has excellent dispersibility in organic systems.

[0027] Example 1: The preparation steps for silicone rubber used in bathroom seals (O-rings) for dirty environments are as follows: (1) Place 1000g of methyl vinyl silicone rubber raw rubber (model 110-2, vinyl content 0.15 mol%) in a two-roll mill, set the roller temperature to below 50℃, the roller gap to about 1mm, and pass through the mill 5 times to form a uniform plasticized rubber. (2) Place 800g of lubricant Lub-1, 2000g of methyl vinyl silicone rubber raw rubber, 750g of fumed silica and 150g of hydroxyl silicone oil in a mixer; mix at 80°C and 60rpm for 15 minutes to prepare a pre-composite masterbatch with uniform lubricant dispersion.

[0028] (3) Set the roller temperature on the open mill to 45°C, and then add the components in the following order: add 800g of the plasticized rubber obtained in step (1), add the pre-composite masterbatch prepared in step (2), and mix thoroughly; then add 100g of fumed silica, and after the powder is fully absorbed and the roller is smooth, add in sequence: 30g of surface silanized copper-loaded nano silica, 5g of heat stabilizer cerium hydroxide and 3g of antioxidant 1010, and mix thoroughly; then add 0.5g of vulcanization inhibitor methylbutyninol, and mix thoroughly; finally add 10g of crosslinking agent DBPMH; the entire operation requires multiple triangular wrapping (at least 8 times) to ensure that each component is evenly dispersed; the total mixing time is controlled at about 25 minutes; and a uniformly mixed rubber compound is obtained. (4) Fill the uniformly mixed rubber material obtained in step (3) into the preheated O-ring mold, set the mold temperature to 165℃, and then place the mold on a flat vulcanizing machine for a first-stage vulcanization reaction. The specific conditions are: the reaction temperature is 165℃, and the reaction pressure adopts variable pressure vulcanization technology. Specifically, after the mold is closed, the pressure is controlled at 5MPa for 0-1 minutes; the pressure rises to 8MPa for 1-3 minutes; the pressure is maintained at 12MPa for 3-10 minutes, and the total vulcanization time is 10 minutes to obtain the first-stage vulcanized product. (5) Take out the first vulcanized O-ring blank (with a small amount of flash) obtained in step (4) from the mold and put it into the blower oven for a second vulcanization reaction. The specific conditions are: reaction temperature is 200℃ and reaction time is 2 hours. After the reaction is completed, trim the flash to obtain a finished O-ring with a smooth surface and accurate dimensions.

[0029] The prepared O-rings were subjected to the following performance tests: 1. Friction coefficient test: The ball-disc friction and wear tester was used. The mating part was a stainless steel ball (6mm in diameter), the load was 5N, the sliding speed was 50mm / s, and the test time was 30 minutes. Test results: The initial dynamic friction coefficient of the prepared O-ring sample was 0.36. After 10,000 cycles of reciprocating friction, the friction coefficient stabilized at 0.37.

[0030] 2. Mechanical properties were tested according to the relevant national standards, as follows: The tensile stress-strain properties were determined according to the national standard GB / T 528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber". The results showed that the tensile strength of the prepared O-ring was 9.6 MPa, the elongation at break was 670%, and the tear strength was 33 kN / m.

[0031] Hardness testing was conducted according to the national standard GB / T 531.1-2008 "Test Methods for Indentation Hardness of Vulcanized Rubber or Thermoplastic Rubber - Part 1: Shore Hardness Tester Method (Shore Hardness)". The results show that the prepared O-ring has a hardness of 83HA, making it suitable for high-pressure applications.

[0032] Compression set was determined according to the national standard GB / T 7759.1-2015 "Determination of Compression Set of Vulcanized Rubber or Thermoplastic Rubber - Part 1: High Temperature Conditions". The results showed that the O-ring prepared had a compression set of only 7% under the conditions of 200℃ and 20MPa, exhibiting excellent resistance to compression set.

[0033] The wear resistance test was conducted according to the national standard GB / T 1689-1998 "Determination of Abrasion Resistance of Vulcanized Rubber (Rotating Roller Abrasion Tester Method)". The results showed that the O-rings prepared after the wear resistance test had a wear amount controlled within 0.2 mm and no cracks appeared, indicating that they have a long service life under dynamic working conditions.

[0034] The dynamic sealing test was conducted according to the national standard GB / T 3452.2-2007 "Performance Test Specification for O-rings for Hydraulic and Pneumatic Use". The results show that after 100,000 cycles, the wear of the prepared O-ring was only 0.1 mm, and no cracks appeared, demonstrating good dynamic sealing performance.

[0035] The low-temperature brittleness test was conducted according to the national standard GB / T 1682-1994 "Determination of Low-Temperature Brittleness of Vulcanized Rubber (Single Sample Method)". The results showed that the prepared O-rings did not exhibit brittle fracture at -40℃, indicating that they have good low-temperature performance.

[0036] 3. Antibacterial properties were determined according to ISO 22196, using Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 6538 as the bacterial strains. The results showed that the prepared O-rings had an antibacterial rate greater than 99.9% against both bacterial strains. After soaking the O-rings in hot water at 90℃ for 168 hours, the antibacterial rate remained greater than 99%. 4. Dynamic friction-thermal immersion cycle test conditions are as follows: Simulating a bathroom environment: The O-ring samples were immersed in an aqueous solution containing 1% sodium dodecylbenzenesulfonate at 60℃ and subjected to periodic reciprocating friction (1000 times per hour) and 100 cycles before friction performance testing. The results show that the friction coefficient of the prepared O-ring remains stable, with a fluctuation range of ±0.12, and no obvious wear or cracks on the surface.

[0037] Example 2: The preparation of silicone rubber for dirty environments is described in Example 1, except that the lubricant Lub-1 is replaced with Lub-2. All other steps are the same as in Example 1 to obtain silicone rubber with fluorinated hydrocarbon segment modified siloxane lubricant.

[0038] The obtained silicone rubber was made into O-rings and its performance was tested according to Example 1; the results are as follows: The initial dynamic friction coefficient of the prepared O-ring sample was 0.31, and after 10,000 cycles of reciprocating friction, the friction coefficient stabilized at 0.32.

[0039] The prepared O-ring has a tensile strength of 11.7 MPa, an elongation at break of 720%, and a tear strength of 42 kN / m.

[0040] The hardness of the prepared O-ring is 76HA. The prepared O-ring exhibited a compression set of only 4% under conditions of 200℃ and 20MPa, demonstrating excellent resistance to compression deformation.

[0041] The O-rings prepared underwent wear resistance testing, and the wear amount was controlled within 0.1 mm without any cracks appearing.

[0042] The prepared O-rings showed only 0.1 mm of wear after 100,000 cycles and no cracks appeared, demonstrating good dynamic sealing performance.

[0043] The prepared O-rings did not exhibit brittle fracture at -60℃, indicating that they have good low-temperature performance.

[0044] The prepared O-rings exhibited antibacterial rates greater than 99.9% against both bacterial strains. Even after immersing the O-rings in 90°C hot water for 168 hours, their antibacterial rate remained greater than 99%. The prepared O-rings maintained a stable coefficient of friction after dynamic friction-thermal immersion cycle testing, with a fluctuation range of ±0.06, and no obvious wear or cracks on the surface.

[0045] This demonstrates that the use of the fluorinated lubricant Lub-2 effectively improves the mechanical properties of silicone rubber and its adaptability to complex chemical environments.

[0046] Example 3: The preparation of silicone rubber and O-rings for dirty environments is based on Example 1, except that the pressure conditions of the first vulcanization reaction in step (4) are changed to a constant pressure of 12 MPa throughout the entire first vulcanization reaction, while the other conditions are the same as in Example 1.

[0047] The performance of the prepared O-ring was tested according to Example 1: the main focus was on the effect of variable pressure vulcanization on the coefficient of friction, while other performance differences were not significant; the results showed that the initial dynamic coefficient of friction of the prepared O-ring sample was 0.38, and after 10,000 cycles of reciprocating friction, the coefficient of friction stabilized at 0.41.

[0048] It can be seen that the O-ring sample prepared by pressure swing vulcanization in Example 1 exhibits a lower surface friction coefficient. This is mainly because pressure swing vulcanization technology can guide the lubricating components to accumulate in the surface area of ​​the matrix, forming a silicone rubber material with gradient lubrication function.

[0049] Comparative Example 1: The preparation of silicone rubber and O-rings for dirty environments is described in Example 1, except that the lubricant in step (2) is replaced with polydimethylsiloxane oil; the amount of copper-loaded nano-silica with silanized antibacterial agent in step (2) is adjusted to 0; and all other conditions are the same as in Example 1.

[0050] The performance of the prepared O-rings was tested according to Example 1, and the results are as follows: The initial dynamic friction coefficient of the prepared O-ring sample was 0.55, and after 10,000 cycles of reciprocating friction, the friction coefficient stabilized at 0.61.

[0051] The prepared O-ring has a tensile strength of 8.9 MPa, an elongation at break of 570%, and a tear strength of 31 kN / m.

[0052] The hardness of the prepared O-ring is 78HA. The prepared O-ring had a compression set of 10% under conditions of 200℃ and 20MPa.

[0053] The O-rings prepared underwent wear resistance testing, and the wear amount was controlled within 0.4 mm, with slight cracks appearing.

[0054] The prepared O-rings exhibited slight brittle fracture at -30℃.

[0055] The prepared O-ring showed an antibacterial rate of 8.2% against Escherichia coli and an antibacterial rate of 11.6% against Staphylococcus aureus. The friction coefficient of the prepared O-ring was tested under dynamic friction-thermal immersion cycle test. The friction coefficient fluctuated within the range of ±0.33, and the surface showed slight wear and cracks.

Claims

1. A method for preparing silicone rubber for use in dirty environments, characterized in that, Includes the following steps: (1) A portion of methyl vinyl silicone rubber raw rubber is plasticized to obtain plasticized raw rubber; (2) Another portion of methyl vinyl silicone rubber raw rubber, all internal lubricant, some reinforcing filler and all structure control agent are premixed and heat-treated to form a pre-composite masterbatch with uniformly dispersed internal lubricant; wherein, the internal lubricant is one of polyether-siloxane macromolecule or fluorinated polyether-siloxane macromolecule; the polyether-siloxane macromolecule is prepared by the following method: vinyl-terminated dimethyl polysiloxane, hydrogen-containing silicone oil and allyl methoxy polyoxyethylene ether are reacted under the catalysis of a platinum catalyst; the fluorinated polyether-siloxane macromolecule is prepared by the following method: dielyl perfluoropolyether, allyl methoxy polyoxyethylene ether, vinyl-terminated dimethyl polysiloxane and hydrogen-containing silicone oil are reacted under the catalysis of a platinum catalyst; (3) The raw rubber obtained in step (1), the pre-composite masterbatch obtained in step (2), the remaining reinforcing filler, antibacterial agent, heat stabilizer, antioxidant, vulcanization inhibitor and crosslinking agent are added in sequence and then fully mixed to obtain a uniformly mixed rubber compound; the antibacterial agent is copper-loaded nano-silica with surface silanization. (4) After the uniformly mixed rubber compound obtained in step (3) is molded, a vulcanization reaction is carried out. The specific conditions are: the reaction temperature is 160-170℃, the reaction time is 5-15 minutes, and the pressure is variable pressure vulcanization technology; a vulcanized product is obtained. (5) The product obtained in step (4) after one-stage vulcanization is subjected to a two-stage vulcanization reaction. The specific conditions are: treatment at 180-200℃ for 2-4 hours to obtain the silicone rubber for dirty environments.

2. The method for preparing silicone rubber for dirty environments according to claim 1, characterized in that, The structuring control agent is vinyl hydroxyl silicone oil.

3. The method for preparing silicone rubber for dirty environments according to claim 1, characterized in that, The structuring control agent is hydroxyl silicone oil.

4. The method for preparing silicone rubber for dirty environments according to claim 1, characterized in that, The reinforcing filler is fumed silica.

5. The method for preparing silicone rubber for dirty environments according to claim 1, characterized in that, The specific conditions for the pressure swing vulcanization technology described in step (4) are: apply a lower pressure in the early stage of vulcanization, and then increase it to the normal vulcanization pressure.

6. The method for preparing silicone rubber for dirty environments according to claim 1, characterized in that, The two-stage vulcanization reaction described in step (5) is carried out in a blower oven.

7. The silicone rubber for dirty environments prepared according to any one of claims 1-6, characterized in that, The silicone rubber comprises, by weight, the following components: methyl vinyl silicone rubber raw rubber: 100 parts; reinforcing filler: 20-60 parts; Crosslinking agent: 0.5-3 parts; Structure control agent: 1-5 parts; Internal lubricant: 1-15 parts; Antibacterial agent: 0.5-10 parts; Heat stabilizer: 0.1-3 parts; Antioxidant: 0.1-2 parts; Vulcanization inhibitor: 0.01-0.5 parts; wherein the internal lubricant is a polyether-siloxane macromolecule, the molecular structure of which includes a polydimethylsiloxane backbone, a polyether segment and at least one reactive functional group that can be co-vulcanized with a silicone rubber matrix.

8. An article made of silicone rubber for use in dirty environments, prepared by the method according to any one of claims 1-6, characterized in that, The products are O-rings, sealing strips, shower hoses, or kitchen utensil handles.

9. The use of a silicone rubber for dirty environments prepared by the method of any one of claims 1-6 in the preparation of seals or contact parts for bathroom or cleaning appliances.