Anti-aging silica gel sealing element and preparation method thereof

Abstract

The invention relates to the field of sealing materials and preparation, in particular to an anti-aging silica gel sealing element and a preparation method thereof. The composition is composed of the following raw materials in percentage by weight: 15-35% of silicon dioxide; 60 to 80% of polysiloxane; 1 to 5% of dimethyl polysiloxane; the balance is a vulcanizing agent; the polysiloxane is prepared from vinyl type polysiloxane, polyhedral oligomeric silsesquioxane, cyclic polysiloxane, linear-functionalized silicone oil and branched / oligomeric polysiloxane; the polysiloxane is prepared from vinyl type polysiloxane, polyhedral oligomeric silsesquioxane, cyclic polysiloxane, linear-functionalized silicone oil and branched / oligomeric polysiloxane; the linear-functionalized silicone oil is epoxy phenyl silicone oil and / or phenyl silicone oil containing hydrogen on the end side; the polyhedral oligomeric silsesquioxane is prepared from acrylic ester type polyhedral oligomeric silsesquioxane and silanol type polyhedral oligomeric silsesquioxane; the raw materials in polysiloxane are compounded according to a specific ratio to form a synergistic effect of main chain support-branch chain function-crosslinking reinforcement, a multi-mechanism crosslinking system is constructed, the network compactness and the structural stability are improved, and the sealing performance and the aging resistance of the sealing element are enhanced.

Description

Technical Field

[0001] This application relates to the field of sealing materials and their preparation, and in particular to an aging-resistant silicone sealant and its preparation method. Background Technology

[0002] Silicone seals have been widely used in numerous fields due to their unique advantages. Silicone material possesses excellent elasticity, enabling it to form a tight fit between components of different shapes and sizes, effectively preventing the leakage of liquids, gases, and other substances. Simultaneously, it exhibits good flexibility, withstanding a certain degree of deformation without damage, adapting to various complex working environments. Furthermore, silicone is chemically stable, exhibiting good resistance to most chemical substances, and is non-toxic, odorless, and biocompatible, making it an ideal sealing material in fields with extremely high safety and hygiene requirements, such as medical, food, and electronics. In the medical field, silicone seals play an indispensable role, especially when used in medical equipment such as color Doppler ultrasound machines that come into short-term contact with the human body. Silicone seals must not only ensure the internal sealing of the equipment to prevent liquid or gas leakage from affecting its normal operation, but also ensure that they do not cause any harm to the human body during contact.

[0003] In practical applications, existing technologies employ a series of measures to improve the aging resistance of silicone seals. One common method is the addition of antioxidants, which can inhibit the oxidation reaction of silicone materials under oxygen conditions, thus slowing down the aging process. Additionally, some existing technologies attempt to introduce fluorine-containing substances to improve the weather resistance of silicone seals. Fluorine-containing substances have high chemical stability and corrosion resistance, and can enhance silicone's resistance to substances such as alcohol and medical gels to some extent. Meanwhile, some sealing gaskets with superior sealing performance also exist, meeting the basic sealing requirements of medical devices.

[0004] However, existing technologies have significant drawbacks. Simply adding antioxidants is often insufficient to comprehensively address the performance issues of silicone seals in terms of alcohol and medical gel resistance. In practical applications, silicone seals with added antioxidants still exhibit inadequate alcohol resistance; their performance gradually declines after prolonged contact with alcohol disinfectants, failing to meet the requirements for long-term stable use of medical devices. Introducing substances such as fluorine poses serious potential hazards. Fluorine compounds may possess certain biotoxicity and environmental persistence. When used in medical devices with short-term contact with the human body, they may enter the body through skin contact or equipment leakage, posing potential health risks. Furthermore, the production and processing of fluorine-containing substances are complex, costly, and environmentally polluting. In addition, some existing gaskets have significant shortcomings in simultaneously achieving resistance to yellowing and alcohol, resulting in a gradual decline in sealing performance under long-term exposure to alcohol disinfectants and medical gels, failing to provide long-term reliable sealing for medical devices. Summary of the Invention

[0005] Based on achieving better sealing and mechanical properties, this application further improves the resistance to ultraviolet light, heat, oxygen, and alcohol, reducing problems such as yellowing, swelling, and poor sealing that occur when silicone seals are used in medical devices. It provides an aging-resistant silicone seal and its preparation method.

[0006] Firstly, an aging-resistant silicone sealant is composed of the following raw materials by weight percentage: 15-35% silicon dioxide; Polysiloxane 60-80%; Dimethylpolysiloxane 1-5%; The remainder is vulcanizing agent; The polysiloxane is composed of vinyl polysiloxane, cage-like polysilsesquioxane, cyclic polysiloxane, linear-functionalized silicone oil, and branched / oligomeric polysiloxane in a weight ratio of 10:(0.5-1):(1-3):(1-5):(2-3); The linear-functionalized silicone oil is an epoxy-based phenyl silicone oil and / or an end-side hydrogen-containing phenyl silicone oil; The cage-like polysilsesquioxane is composed of acrylate-type cage-like polysilsesquioxane and silanol-type cage-like polysilsesquioxane.

[0007] By precisely controlling the raw material composition and distribution ratio of silicone sealants, a multi-dimensional synergistic polymer network structure is constructed, enabling the raw materials to complement and enhance each other's performance, thus endowing the product with excellent sealing stability and long-term aging resistance. With a polysiloxane composite system of specific proportions as the core, each component surrounds a basic network built around vinyl-type polysiloxane, forming a synergistic effect of "main chain support - branch chain function - cross-linking reinforcement," providing core assurance for sealing performance and aging resistance.

[0008] The various polysiloxane components and the vulcanizing agent work synergistically to form a multi-mechanism crosslinking system of "hydrosilicon addition-epoxy ring opening-hydrogen bonding," which improves the density of the network and enhances the structural stability of the seal. Silica, as a key inorganic filler, achieves a synergistic effect of "interfacial reinforcement-uniform dispersion" with the organic phase through the functional design of the polysiloxane composite system. This improves its dispersion uniformity and interfacial bonding force between the inorganic filler and the organic matrix, fully leveraging the reinforcing effect of silica and reducing stress concentration and aging defects caused by filler agglomeration.

[0009] Through the synergistic effect of all components, the sealing performance and aging resistance of the seal are comprehensively improved. In terms of sealing performance, the "rigid-flexible" synergistic network structure of the polysiloxane system, combined with the reinforcing effect of silica, gives the seal excellent elastic resilience and good mechanical strength, enabling it to maintain a tight fit to the sealing surface for a long time and effectively prevent media leakage. Dimethyl polysiloxane can improve the mixing uniformity of each component, form a protective film on the surface of the seal, reduce frictional loss of the sealing surface, and improve sealing stability.

[0010] In terms of aging resistance, the dense cross-linked network constructed by the multi-component synergy and the protective effect of functional groups give the seal excellent resistance to aging and yellowing, corrosion and swelling. It can block the penetration of ultraviolet rays and corrosive media, reduce the swelling rate, avoid the migration and precipitation of small molecule components, reduce aging failure caused by component loss, and enable the seal to maintain stable sealing performance and appearance during long-term use.

[0011] As the "initiator" of the cross-linking reaction, the vulcanizing agent activates the active sites of each polysiloxane component, ensuring the full progress of the multi-dimensional cross-linking reaction. It also synergistically regulates the cross-linking rate with dimethyl polysiloxane, guaranteeing the uniformity and stability of the sealing structure. Simultaneously, all components exhibit good biocompatibility, meeting the material safety requirements of medical devices. This effectively addresses the aging and failure issues that arise during high-frequency sterilization and long-term operation of medical devices, reducing equipment maintenance costs and improving the reliability and safety of medical device operation.

[0012] Preferably, the ratio of the amount of epoxy-based phenyl silicone oil to the amount of end-side hydrogen-containing phenyl silicone oil is 1:(1-3).

[0013] Epoxy-based phenyl silicone oil and end-hydrogen-containing phenyl silicone oil were compounded at a ratio of 1:(1-3). The two products exhibited a synergistic effect, further enhancing the overall performance of silicone sealants. The epoxy groups of the epoxy-based phenyl silicone oil could undergo ring-opening reactions with the silanol groups of cage-like polysilsesquioxanes and the active groups of branched / oligomeric polysiloxanes, forming stronger chemical bonds. The hydrogen-containing groups of the end-hydrogen-containing phenyl silicone oil could combine with the vinyl groups of vinyl-type polysiloxanes through hydrosilylation reactions. Simultaneously, the introduction of phenyl groups improved the material's resistance to UV aging and high-temperature performance. After compounding, the stability and aging resistance of the cross-linked network were strengthened through a synergistic mechanism of "group reaction-functional superposition."

[0014] Preferably, the acrylate-type cage-like polysilsesquioxane is acryloyloxypropyl-glycidyl etheroxypropyl cage-like polysilsesquioxane and / or methacryloyloxypropyl cage-like polysilsesquioxane.

[0015] An interlocking cross-linked network with multiple reactive sites was constructed, achieving simultaneous improvement in network rigidity and toughness. This enhanced the overall rigidity and density of the entire cross-linked network, effectively resisting the penetration and swelling of alcohol molecules, endowing the material with superior tear resistance and toughness, avoiding embrittlement, and ensuring the structural integrity of the seal during long-term compression-rebound cycles. Furthermore, it achieved "interfacial synergy" with linear-functionalized silicone oil and fillers, realizing directional optimization of performance, improving the compatibility and stress transfer efficiency between inorganic fillers and the organic matrix, enriching UV-resistant and anti-yellowing phenyl groups in the material interface region susceptible to external corrosion, achieving "precise defense" against aging, improving cross-linking uniformity and network strength, and maintaining the material's excellent elasticity and low compression set. This resulted in a breakthrough in overall performance.

[0016] In the ethanol swelling resistance test, the volume change rate is less than 1%, the tensile strength retention rate is greater than 93%, the yellowing index increase is reduced and the appearance is well maintained in the UV aging resistance test, the deformation recovery rate is higher, the sealing force attenuation rate is extremely low and the service life is significantly extended in the long-term compression set test, and the mechanical properties are tensile strength ≥8.5MPa and elongation at break ≥550%.

[0017] Preferably, the silanol-type cage-like polysilsesquioxane is heptaisobutyltrisilanol cage-like polysilsesquioxane and / or octaphenyltetrasilanol double-clip type polysilsesquioxane.

[0018] The silanol-type cage-like polysilsesquioxane is limited to heptaisobutyltrisilanol cage-like polysilsesquioxane and / or octaphenyltetrasilanol double-clip type polysilsesquioxane. It is combined with polysiloxane composed of vinyl-type polysiloxane, cage-like polysilsesquioxane, cyclic polysiloxane, linear-functionalized silicone oil, and branched / oligomeric polysiloxane in a specific weight ratio, as well as silica, dimethyl polysiloxane and vulcanizing agent, to construct a multi-dimensional synergistic polymer network structure. This allows the raw materials to form a complementary and reinforcing effect at the performance level, improving the sealing stability and long-term aging resistance of the seal, and meeting the stringent requirements of medical equipment for material durability and safety.

[0019] In the cross-linking system, silanol-type cage-like polysilsesquioxanes form hydrogen bonds with the hydroxyl groups of silica, constructing inorganic-organic cross-linking points and enhancing the network's density and structural stability. Simultaneously, in conjunction with other components in the polysiloxane system, it improves the dispersion uniformity of silica and the interfacial bonding force between the inorganic filler and the organic matrix, fully leveraging the reinforcing effect of silica and reducing stress concentration and aging defects caused by filler agglomeration. The dense cross-linked network constructed by the multi-component synergy and the protective effect of functionalized groups endow the seal with excellent resistance to aging, yellowing, corrosion, and swelling. The strong chemical bonds between components prevent the migration and precipitation of small molecules, reducing aging failure caused by component loss, and ensuring stable sealing performance and appearance during long-term use of medical equipment.

[0020] Preferably, the cyclic polysiloxane is methacryloyloxypropylcyclotetrasiloxane.

[0021] The cyclotetrasiloxane backbone of methacryloyloxypropylcyclotetrasiloxane can form "flexible buffer segments" in the network, significantly improving the low-temperature elasticity and processing fluidity of the seal and reducing internal stress during molding. The methacryloyloxypropyl groups on its molecular chain act as highly active reaction sites, capable of free radical copolymerization with the vinyl groups of vinyl-type polysiloxanes, and forming synergistic reactions with the acrylate groups of acryloyloxypropyl-glycidyloxypropyl cage-type polysilsesquioxane and methacryloyloxypropyl cage-type polysilsesquioxane, strengthening the bond with rigid units. It can also crosslink with the branch sites of branched / oligomeric polysiloxanes, filling gaps in the main chain network and constructing a "cyclic-linear-branched" interwoven multi-element network structure, enhancing network integrity and resistance to deformation. Combined with the "rigid-flexible" synergistic network structure of the polysiloxane system, the reinforcing effect of silica, and the crosslinking enhancement effect of pentamethylphenyl dihydrotrisiloxane, the seal possesses excellent elastic resilience and mechanical strength, preventing media leakage.

[0022] Synergistically, it improves the mixing uniformity of each component with dimethyl polysiloxane, forms a protective film on the surface of the seal, reduces frictional loss of the sealing surface, and improves sealing stability. Its cyclic structure and the cage-like structure of cage-like polysilsesquioxane form a "double physical barrier". Branched tetradecyl hexasiloxane fills the barrier gaps, and quadruple protection can effectively block the penetration of ultraviolet rays and corrosive media. The methyl side chain enhances the barrier to non-polar media, achieving all-round corrosion protection. Combined with the conjugated structure of phenyl groups and dense cross-linked network, the seal has excellent resistance to aging and yellowing, corrosion and swelling, and maintains stable sealing performance and appearance during long-term use of medical equipment.

[0023] Preferably, the branched / oligomeric polysiloxane is branched tetradecyl hexasiloxane and / or pentamethylphenyl dihydrotrisiloxane.

[0024] The "rigid-flexible" synergistic network structure of the polysiloxane system, combined with the reinforcing effect of silica, gives the seal both excellent elastic resilience and good mechanical strength, enabling it to maintain a tight fit with the sealing surface for a long time and effectively prevent media leakage. Dimethyl polysiloxane can synergistically improve the mixing uniformity of each component with branched tetradecyl hexasiloxane, while forming a protective film on the surface of the seal to reduce frictional wear on the sealing surface and further improve sealing stability.

[0025] The dense cross-linked network constructed by multiple components and the protective effect of functional groups give the seals excellent resistance to aging, yellowing, corrosion, and swelling. The cage-like structure of the cage-like polysilsesquioxane and the cyclic structure of the methacryloyloxypropylcyclotetrasiloxane form a "double physical barrier." The short-chain branched structure of the branched tetradecylmethylhexasiloxane can fill the barrier gaps, and the phenyl group of the pentamethylphenyldihydrotrisiloxane and the phenyl group of the linear-functionalized silicone oil form a "conjugated protective layer." This quadruple protection can effectively block the penetration of ultraviolet rays and corrosive media. Among them, the methyl side chain of the methacryloyloxypropylcyclotetrasiloxane enhances the barrier properties against non-polar media, the ether bond structure of the acryloyloxypropyl-glycidyl etheroxypropyl cage-like polysilsesquioxane strengthens the protection against polar media, and the pentamethylphenyldihydrotrisiloxane improves the resistance to acid and alkali disinfectants, achieving all-round corrosion protection.

[0026] The conjugated structure of the phenyl group can absorb ultraviolet energy and reduce photo-aging breakage of molecular chains; the dense cross-linked network can prevent corrosive media from penetrating into the material and reduce the swelling rate; at the same time, the strong chemical bonds between the components prevent the migration and precipitation of small molecule components, reduce aging failure caused by component loss, and enable the seal to maintain stable sealing performance and appearance during long-term use of medical equipment.

[0027] Preferably, the silica has a particle size of 1-30 micrometers.

[0028] Based on silicone seals composed of silica, polysiloxane, dimethylpolysiloxane, and vulcanizing agent in specific weight percentages, controlling the silica particle size to 1-30 micrometers helps improve the dispersion uniformity of silica in the polysiloxane system, strengthens the interfacial bonding force between inorganic fillers and organic matrix, fully utilizes the reinforcing effect of silica, reduces stress concentration and aging defects caused by filler agglomeration, and thus improves the mechanical properties and aging resistance of the seal.

[0029] Preferably, the vulcanizing agent is one of bis(2,5-diphenyl), bis(2,4-diphenyl), or platinum water.

[0030] Dual-25, Dual-24, and Platinum Water, as vulcanizing agents, can precisely activate the active sites of each polysiloxane component, ensuring that the multi-dimensional cross-linking reaction proceeds fully; in synergy with dimethyl polysiloxane, they can regulate the cross-linking rate, avoiding internal stress and defects caused by excessively rapid cross-linking, and ensuring the uniformity and stability of the sealing structure.

[0031] Preferably, the dimethylpolysiloxane is dimethyl silicone oil.

[0032] Dimethyl silicone oil can synergistically improve the mixing uniformity of each component with branched tetradecyl hexasiloxane, while forming a protective film on the surface of the seal to reduce frictional loss of the sealing surface and further improve sealing stability. The synergistic effect of the vulcanizing agent and dimethyl silicone oil can regulate the crosslinking rate and avoid internal stress and defects caused by excessive crosslinking, further ensuring the uniformity and stability of the seal structure.

[0033] Secondly, an aging-resistant silicone sealant is obtained by the following method: According to the weight percentage: weigh silicon dioxide, polysiloxane, and dimethylpolysiloxane, mix them evenly, and knead them to obtain a mixture; then mix the vulcanizing agent with the mixture evenly, put it into a mold, and vulcanize it to obtain a silicone seal.

[0034] Silica, polysiloxane, and dimethylpolysiloxane are weighed and mixed evenly according to their weight percentages and then kneaded. After adding a vulcanizing agent and kneading, the mixture is vulcanized and molded. This process allows the raw materials to fully mix and react. Under the synergistic effect of the polysiloxane composite system, silica, dimethylpolysiloxane, and vulcanizing agent, the seal has excellent elastic recovery and mechanical strength, effectively preventing media leakage. It also has good resistance to aging, yellowing, corrosion, and swelling. At the same time, the good biocompatibility of each component meets the material safety requirements of medical devices.

[0035] In summary, this application includes at least one of the following beneficial technical effects: 1. The raw materials in polysiloxane are compounded in a specific ratio to form a synergistic effect of "main chain support - branch chain function - cross-linking enhancement", constructing a multi-mechanism cross-linking system of "hydrosilicon addition - epoxy ring opening - hydrogen bonding", which improves network density and structural stability, and enhances the sealing performance and aging resistance of the seals. 2. The linear-functionalized silicone oil is composed of epoxy-based phenyl silicone oil and end-side hydrogen-containing phenyl silicone oil. The two work synergistically to enhance the stability and aging resistance of the cross-linked network. Combined with the polysiloxane system and silica, it reduces the compression set of the seal, improves mechanical properties, optimizes sealing performance, and ensures a long-term stable sealing effect. 3. Cage-type polysilsesquioxane is composed of acrylate-type cage-type polysilsesquioxane and silanol-type cage-type polysilsesquioxane. The silanol-type cage-type polysilsesquioxane is heptaisobutyltrisilanol cage-type polysilsesquioxane and / or octaphenyltetrasilanol double-clip type polysilsesquioxane. The acrylate-type cage-type polysilsesquioxane is acryloyloxypropyl-glycidyloxypropyl cage-type polysilsesquioxane and / or methacryloyloxypropyl cage-type polysilsesquioxane. They work synergistically and, when combined with other systems in polysiloxane, further enhance the sealing properties of the seal, making it resistant to aging and yellowing, corrosion and swelling, reducing the swelling rate, and minimizing failures caused by aging and component loss. It is suitable for medical devices. Detailed Implementation

[0036] The present application will be further described in detail below with reference to the embodiments.

[0037] Introduction to some raw materials: Vinyl polysiloxanes have a number-average molecular weight of 10,000-20,000 and a vinyl content of 1.3-1.9%. Dimethyl silicone oil CAS No.: 63148-62-9; Pentamethylphenyl dihydrotrisiloxane CAS No.: 17962-34-4; IOTA-279 epoxy-based phenyl silicone oil; IOTA234, a hydrogen-containing phenyl silicone oil with end-side hydride. Branched tetradecyl hexasiloxane IOTA 20576; Acryloyloxypropyl-glycidyl oxypropyl cage-type polysilsesquioxane cotion® POSS4029; Octaphenyltetrasilyl alcohol double-ply polysilsesquioxane Ecotion® DDSQ501; Heptaisobutyltrisilyl alcohol cage-like polysilsesquioxane Ecotion® POSS201; Methacryloxypropyl cage-type polysilsesquioxane Ecotion® CTS102; The molecular structure of methacryloyloxypropylcyclotetrasiloxane is as follows: . Example

[0038] Example 1 An aging-resistant silicone sealant is obtained by the following method: Polysiloxane: Composed of vinyl polysiloxane, cage-like polysilsesquioxane, cyclic polysiloxane, linear-functionalized silicone oil, and branched / oligomeric polysiloxane in a weight ratio of 10:0.5:2.5:4:2.

[0039] The cage-like polysilsesquioxane is composed of acrylate-type cage-like polysilsesquioxane and silanol-type cage-like polysilsesquioxane in a weight ratio of 1:1.

[0040] The linear-functionalized silicone oil is an epoxy-phenyl silicone oil; the acrylate-type cage-like polysilsesquioxane is an acryloyloxypropyl-glycidyl oxypropyl cage-like polysilsesquioxane; the silanol-type cage-like polysilsesquioxane is a heptaisobutyltrisilol cage-like polysilsesquioxane.

[0041] Dimethylpolysiloxane is dimethyl silicone oil; silica has a particle size of 5 micrometers.

[0042] By weight percentage: Weigh silica, polysiloxane, and dimethylpolysiloxane and place them in a kneader. Stir at 60 rpm while simultaneously raising the temperature to 155°C at a rate of 2°C / min. Knead and maintain the temperature for 2 hours to obtain a mixture. Then, place the vulcanizing agent (bis(2,5)) and the mixture into a two-roll mill and use a continuous triangular-wrapping mixing process: first, wrap the material around the roller until the surface is smooth and free of particles, then repeatedly wrap it in a triangular shape 15 times, for a total mixing time of 20 minutes, until the vulcanizing agent and the base rubber compound form a homogeneous system, obtaining a mixed rubber compound. Then, place the mixed rubber compound into a mold and vulcanize for 10 minutes at a temperature of 160°C to obtain silicone sealant. The above raw material dosages are detailed in Table 1.

[0043] Example 2-3 The difference between Examples 2-3 and Example 1 is that the amount of raw materials used is different, as shown in Table 1. Table 1. Raw material usage (by weight percentage) for Examples 1-3

[0044] Example 4 The difference between Example 4 and Example 2 is that the linear-functionalized silicone oil is an end-side hydrogen-containing phenyl silicone oil.

[0045] Example 5 The difference between Example 5 and Example 2 is that the linear-functionalized silicone oil is composed of epoxy-based phenyl silicone oil and end-side hydrogen-containing phenyl silicone oil in a weight ratio of 1:1.

[0046] Example 6 The difference between Example 6 and Example 5 is that the acrylate-type cage-like polysilsesquioxane is methacryloyloxypropyl cage-like polysilsesquioxane.

[0047] Example 7 The difference between Example 7 and Example 5 is that the acrylate-type cage-like polysilsesquioxane is composed of acryloyloxypropyl-glycidyloxypropyl cage-like polysilsesquioxane and methacryloyloxypropyl cage-like polysilsesquioxane in a weight ratio of 1:3.

[0048] Example 8 The difference between Example 8 and Example 7 is that the silanol-type cage-like polysilsesquioxane is composed of heptaisobutyltrisilanol cage-like polysilsesquioxane and octaphenyltetrasilanol double-clip type polysilsesquioxane in a weight ratio of 3:1.

[0049] Example 9 The difference between Example 9 and Example 2 is that the branched / oligomeric polysiloxane is pentamethylphenyldihydrotrisiloxane.

[0050] Example 10 The difference between Example 10 and Example 2 is that the branched / oligomeric polysiloxane is composed of branched tetradecyl hexasiloxane and pentamethylphenyl dihydrotrisiloxane in a weight ratio of 2:1.

[0051] Example 11 The difference between Example 11 and Example 9 is that the branched / oligomeric polysiloxane is composed of branched tetradecyl hexasiloxane and pentamethylphenyl dihydrotrisiloxane in a weight ratio of 2:1.

[0052] Comparative Example Comparative Example 1 The difference between Comparative Example 1 and Example 2 is that the cage-like polysilsesquioxane is replaced with an equal amount of vinyl-type polysiloxane.

[0053] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that linear-functionalized silicone oil is replaced with an equal amount of vinyl polysiloxane.

[0054] Comparative Example 3 The difference between Comparative Example 3 and Example 2 is that the cage-like polysilsesquioxane, cyclic polysiloxane, linear-functionalized silicone oil, and branched / oligomeric polysiloxane are all replaced with vinyl polysiloxane in equal amounts.

[0055] Performance testing The mixed rubber compounds obtained from Examples 1-12 and Comparative Examples 1-3 were then placed in a mold and vulcanized for 10 minutes at a temperature of 160°C to obtain several samples for the following experimental tests.

[0056] 1. Mechanical properties The tensile strength and elongation at break were tested according to GB / T 528-2009 (Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber); dumbbell-shaped type 1 specimen (2 mm thick); test conditions: tensile speed 500 mm / min, room temperature 23℃; test instrument: electronic universal testing machine; biocompatibility test: the test was conducted according to GB / T16886.5-2003, in which the mechanical properties were considered qualified when the tensile strength ≥8.5 MPa and the elongation at break ≥550%.

[0057] 2) Sealing performance Compression set: ISO 815-1:2019 (vulcanized rubber or thermoplastic rubber - determination of compression set - Part 1: at room temperature, high temperature and low temperature) Sample size: Φ29mm×12.5mm (O-ring standard sample); Test conditions: 70℃, compression rate 25%, held for 22 hours; Calculation method: Permanent deformation rate = (thickness before compression - thickness after recovery) / (thickness before compression × compression rate) × 100%.

[0058] 3) Weather resistance UV aging and yellowing: Refer to ISO 4892-3:2016 (Plastics - Laboratory light source exposure - Part 3: Fluorescent UV lamps); such as medical equipment such as UV disinfection carts / disinfection lamps (disinfection lamp cover sealing ring, equipment housing waterproof sealing gasket, UV generator interface sealing parts), endoscopes, biochemical analyzers / immunoassay analyzers, ultrasound diagnostic instruments, laser treatment equipment (dermatology, ophthalmology), etc., are easily exposed to UV light directly or indirectly during use.

[0059] Sample size: 50mm×50mm×2mm (consistent with the actual thickness of the seal); Test conditions: UV-A lamp (wavelength 340nm), irradiance 0.89W / (m²・nm), temperature 60℃, relative humidity 50%, continuous irradiation for 1000h; Testing instrument: Colorimeter (CIE Lab system), used to test the growth rate of yellowness index (YI).

[0060] Thermal-oxidative aging yellowing: Refer to ISO 188:2011 (Accelerated aging and heat resistance tests for vulcanized rubber or thermoplastic rubber); Sample size: 50mm×50mm×2mm; Test conditions: Place statically in a hot air aging oven at 120°C for 720h; Test instrument: Color difference meter. Test the yellowing growth rate of the yellowness index (YI).

[0061] The above-mentioned yellowing growth rate of the yellowness index (YI) = the absolute value of the yellowness index (YI) before ultraviolet / thermal-oxidative aging minus the yellowness index (YI) after ultraviolet / thermal-oxidative aging, then divided by the yellowness index (YI) before ultraviolet / thermal-oxidative aging, and finally multiplied by 100%.

[0062] The above-mentioned classification of the yellowing growth rate: Grade A ≤ 25%; 25% < Grade B ≤ 50%; 50% < Grade C ≤ 100%; 100% < Grade D ≤ 120%; Grade E > 120%.

[0063] Alcohol immersion corrosion / swelling: Refer to ASTM D471:2016 (Rubber properties - Effect of immersion in liquids) Sample size: dumbbell shape (standard specimen of GB / T 528-2009); Test medium: 75% medical ethanol (common medical disinfectant); Test conditions: Immerse for 72h at 50°C, stir once every 12h during the period; Calculate the volume change rate and the retention rate of tensile strength. If the volume change rate is less than 1%, it is considered qualified.

[0064] The above experimental data are shown in Table 2 for details Table 2 Experimental data of Examples 1-12 and Comparative Examples 1-3

[0065] Combined with the test data of Example 2 and Comparative Examples 1-3 (see Table 1 for details), the significant performance advantages of the technical solution of this application can be clearly seen. The specific analysis is as follows: Comparison of mechanical properties and sealing performance: The mechanical properties (such as tensile strength, elongation at break, etc.) and volume change rate of Comparative Examples 1-3 did not reach the preset qualified standards, and the core sealing performance index - compression set rate was significantly higher than that of Example 2, indicating that the stability of its sealing structure is insufficient and sealing failure is likely to occur during long-term use; while Example 2 achieved double compliance of mechanical properties and sealing performance through the compounding design of a specific polysiloxane system, with a lower compression set rate and can maintain a tight fit of the sealing surface for a long time.

[0066] Comparison of corrosion and swelling resistance performance: In the corrosion / swelling test of immersion in 75% medical ethanol, the tensile strength retention rates of Comparative Examples 1-3 were all lower than those of Example 2, indicating that their cross-linked network was not dense enough, and ethanol easily penetrated, causing damage to the internal structure of the material and significant performance degradation. In contrast, the tensile strength retention rate of Example 2 was higher (≥93%), which fully demonstrates that the compound system of this application can effectively block the penetration of corrosive media and has better corrosion and swelling resistance.

[0067] Comparison of resistance to aging and yellowing: UV aging yellowing: The yellowness index (YI) growth rate of Example 2 reached the C-level standard (50% < C-level ≤ 100%), while Comparative Examples 1-3 were all at the D-level (100% < D-level ≤ 120%), and some even reached the E-level (E-level > 120%). This indicates that the seal of this application can effectively suppress yellowing under long-term UV irradiation and has better appearance stability. Thermo-oxidative aging and yellowing: The YI growth rate of Example 2 reached the B-level standard (25% < B-level ≤ 50%), while Comparative Examples 1-3 did not reach the B-level, further confirming that the anti-aging and yellowing ability of the system in this application is more comprehensive.

[0068] In summary, the above data fully demonstrates that this application, through the precise compounding of vinyl polysiloxane, cage-like polysilsesquioxane, cyclic polysiloxane, linear-functionalized silicone oil, and branched / oligomeric polysiloxane, achieves a synergistic effect among the components: on the one hand, it constructs a dense and stable multi-mechanism cross-linked network, enhancing mechanical and sealing properties; on the other hand, through the synergistic protection of functional groups and the physical barrier of the network structure, it significantly improves the resistance to aging, yellowing, corrosion, and swelling. Ultimately, this application's silicone seals possess more balanced and superior comprehensive performance, fully meeting the stringent requirements of high-end medical equipment for seals.

[0069] Biocompatibility tests were conducted on the samples obtained from Examples 1-11 and Comparative Examples 1-3. The biotoxicity scores of Examples 1-11 and Comparative Examples 1-3 were 0 [tested according to GB / T16886.5-2003, where: no cytotoxicity (0), slight cytotoxicity (1), moderate cytotoxicity (2), severe cytotoxicity (3)].

[0070] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. An aging-resistant silicone sealant, characterized in that, It consists of the following raw materials by weight percentage: 15-35% silicon dioxide; Polysiloxane 60-80%; Dimethylpolysiloxane 1-5%; the balance is a vulcanizing agent; The polysiloxane is composed of vinyl polysiloxane, cage-like polysilsesquioxane, cyclic polysiloxane, linear-functionalized silicone oil, and branched / oligomeric polysiloxane in a weight ratio of 10:(0.5-1):(1-3):(1-5):(2-3); The linear-functionalized silicone oil is an epoxy-based phenyl silicone oil and / or an end-side hydrogen-containing phenyl silicone oil; the cage-like polysilsesquioxane is composed of acrylate-type cage-like polysilsesquioxane and silanol-type cage-like polysilsesquioxane.

2. The aging-resistant silicone sealant according to claim 1, characterized in that: The ratio of the amount of epoxy-based phenyl silicone oil to the amount of end-side hydrogen-containing phenyl silicone oil is 1:(1-3).

3. The aging-resistant silicone sealant according to claim 1, characterized in that: The acrylate-type cage-like polysilsesquioxane is acryloyloxypropyl-glycidyl etheroxypropyl cage-like polysilsesquioxane and / or methacryloyloxypropyl cage-like polysilsesquioxane.

4. The aging-resistant silicone sealant according to claim 1, characterized in that: The silanol-type cage-like polysilsesquioxane is heptaisobutyltrisilanol cage-like polysilsesquioxane, or is composed of heptaisobutyltrisilanol cage-like polysilsesquioxane and octaphenyltetrasilanol double-clip type polysilsesquioxane.

5. The aging-resistant silicone sealant according to claim 1, characterized in that: The cyclic polysiloxane is methacryloyloxypropylcyclotetrasiloxane.

6. The aging-resistant silicone sealant according to claim 1, characterized in that: The branched / oligomeric polysiloxane is branched tetradecyl hexasiloxane and / or pentamethylphenyl dihydrotrisiloxane.

7. The aging-resistant silicone sealant according to claim 1, characterized in that: The silica has a particle size of 1-30 micrometers.

8. The aging-resistant silicone sealant according to claim 1, characterized in that: The vulcanizing agent is one of bis(2,5), bis(2,4), or platinum water.

9. The aging-resistant silicone sealant according to claim 1, characterized in that: The dimethylpolysiloxane is dimethyl silicone oil.

10. An aging-resistant silicone seal as described in any one of claims 1-9, characterized in that, The following method is used to obtain the silicone sealant: Weigh out silica, polysiloxane, and dimethylpolysiloxane by weight percentage, mix them evenly, and then knead them to obtain a mixture; then mix the vulcanizing agent with the mixture evenly, put it into a mold, and vulcanize it to obtain a silicone sealant.

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