Medical liquid silica gel and preparation method thereof

Abstract

The invention discloses medical liquid silica gel and a preparation method thereof, and relates to the technical field of silica gel materials. The method comprises the following steps: drying vinyl-terminated polydimethylsiloxane with a side chain containing vinyl, and carrying out addition reaction on part of polydimethylsiloxane and dehydrated 1H, 1H, 2H, 2H-perfluorodecyl dimethyl silane to obtain a fluorine-containing modified liquid silica gel matrix; the preparation method comprises the following steps: coating dopamine-coated nano-diamond with a silicon dioxide layer, and then grafting vinyl trimethoxy silane and octyl triethoxy silane, so as to prepare a modified wear-resistant filler; the preparation method comprises the following steps: mixing a fluorine-containing modified liquid silica gel matrix, a modified wear-resistant filler, vinyl MQ silicon resin and a catalyst to prepare a component A; mixing the residual dry base rubber with hydrogen-containing silicone oil and 3-methyl-1-butyne-3-alcohol to prepare a component B; and finally, mixing and curing the component A and the component B. The prepared liquid silica gel has excellent wear resistance and mechanical properties, and is suitable for the field of medical apparatuses and instruments.

Description

Technical Field

[0001] This invention relates to the field of silicone material technology, specifically to a medical liquid silicone and its preparation method. Background Technology

[0002] Liquid silicone, an addition-type silicone material with vinyl-terminated polydimethylsiloxane as its core matrix, has become one of the most widely used polymer materials in the medical field due to its excellent biocompatibility, low-temperature flexibility, high and low temperature resistance, chemical stability, and good molding and processability. It also meets medical biological evaluation standards and medical material requirements. It is extensively used in medical catheters, interventional device accessories, medical dynamic seals, medical aesthetic consumables, dental medical devices, and respiratory circuit connectors, playing an irreplaceable role in clinical diagnosis and treatment and the operation of medical equipment. However, in actual medical applications, most medical liquid silicone products are subjected to dynamic friction, reciprocating contact, or mechanical extrusion for extended periods. The inherent insufficient wear resistance of traditional medical liquid silicone becomes particularly prominent, becoming a key bottleneck limiting its further application in high-end medical fields. For example, the insertion and removal of medical interventional catheters generates continuous interfacial friction, the dynamic sealing of medical seals involves repeated abrasive contact, and repeated use of cosmetic medical consumables also leads to surface friction damage. In these scenarios, traditional liquid silicone is prone to surface scratches, abrasions, and even substrate peeling, which not only significantly shortens the lifespan of medical products and increases the maintenance and replacement costs of medical equipment and clinical use costs, but more seriously, the silicone microparticles generated by wear are prone to dissolution and migration, potentially causing medical safety risks such as inflammation, thrombosis, and foreign body reactions in human tissues. Furthermore, the wear and damage on the product surface can also become attachment sites for bacteria and microorganisms, increasing the probability of clinical infection. In addition, high-end medical devices place higher demands on the wear resistance of silicone products, and the wear rate of traditional liquid silicone is insufficient to meet the needs of precision interventional devices and long-lasting medical seals. Summary of the Invention

[0003] The purpose of this invention is to provide a medical liquid silicone and its preparation method to solve the technical problems mentioned in the background.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing medical-grade liquid silicone includes the following steps: (1) Polydimethylsiloxane with vinyl-terminated end and vinyl-containing side chains is vacuum dried to obtain a dry base adhesive, and then divided into two portions of dry base adhesive. (2) Dehydrate 1H,1H,2H,2H-perfluorodecyldimethylsilane to obtain dehydrated fluorosilane; (3) Under the protection of inert gas, the first dry base glue obtained in step (1) is added to dehydrated fluorosilane in the presence of platinum-vinylsiloxane complex catalyst. After the reaction, the unreacted monomers are removed by vacuum to obtain fluorine-modified liquid silica matrix. (4) Disperse nanodiamonds in a solvent, add dopamine hydrochloride to carry out a polymerization reaction, and form a polydopamine coating layer on the surface of nanodiamonds to obtain PDA@ND powder; (5) A silica layer is coated on the outside of PDA@ND powder by hydrolysis and polycondensation reaction of tetraethyl orthosilicate to obtain PDA@ND@SiO2 dense core-shell filler; (6) Vinyltrimethoxysilane and octyltriethoxysilane were grafted onto the surface of PDA@ND@SiO2 dense core-shell filler to obtain modified wear-resistant filler; (7) Fluorine-modified liquid silica matrix, modified wear-resistant filler, vinyl MQ silicone resin and platinum-vinylsiloxane complex catalyst are mixed, and then ground, dispersed and degassed to obtain component A; (8) Mix the second portion of the dried base adhesive reserved in step (1), the hydrogen-containing silicone oil, and 3-methyl-1-butyn-3-ol to obtain component B; (9) Mix component A and component B evenly, degas and heat to cure, and you will get the product.

[0005] In the technical solution of this invention, the wear resistance of liquid silicone is improved synergistically from the following aspects: (1) The monofunctional hydrofluorosilane 1H,1H,2H,2H-perfluorodecyldimethylsilane is covalently grafted onto the side chain vinyl of polydimethylsiloxane with high vinyl content. This avoids gelation of the system during the grafting process through the design of a single reaction site, maintains the processing fluidity of liquid silicone, and achieves permanent anchoring of low-friction fluoroalkyl segments on the siloxane molecular chain, eliminating the defects of easy migration and precipitation of traditional physical blended fluorine additives and rapid decay of wear resistance. The perfluoro long-chain alkyl grafted onto the molecular chain has extremely low surface energy and will spontaneously accumulate on the material surface during the material curing process, which can significantly reduce the friction coefficient of the material surface and greatly reduce the interfacial adhesion between the friction pair and the silicone surface during the friction process. This reduces the probability of adhesive wear at its source. Simultaneously, the grafted perfluorinated long chains can form molecular-level physical entanglements through hydrophobic interactions and van der Waals forces, significantly improving the cohesive strength and shear resistance of the silicone matrix without compromising its flexibility. This effectively inhibits the slippage, deentanglement, and breakage of siloxane molecular chains during friction, reducing fatigue wear of the matrix. Furthermore, the selected vinyl-based adhesive retains sufficient crosslinkable vinyl sites after fluoroalkyl grafting, forming a uniform and dense three-dimensional crosslinked network during subsequent curing. This further enhances the matrix's resistance to deformation, preventing surface damage, peeling, and wear caused by localized stress concentration during friction. This results in a significant improvement in the intrinsic wear resistance of the silicone matrix, and the modified matrix exhibits stable performance, fully meeting the long-term usage requirements of medical applications.(2) Through multi-layer core-shell structure design, surface active site grafting and covalent cross-linking network weaving, a functionalized wear-resistant filler with a rigid wear-resistant core, interface layer and active grafted outer layer was constructed, maximizing the filler reinforcement effect; the core adopts medical-grade nanodiamond with ultra-high hardness, which has excellent wear resistance and load-bearing capacity. During the friction process, it can bear the main load of the friction interface, transforming the point contact between the friction pair and the silicone matrix into surface contact, greatly reducing contact stress, reducing plastic deformation and adhesive wear of the silicone matrix, thereby enhancing the phase layer and directly improving the wear resistance of the material; through polydopamine coating and in-situ growth of dense silica shell, a complete core-shell coating structure was constructed. The anchoring effect of the polydopamine layer achieved the monodispersion of nanodiamond, avoiding stress concentration and local wear caused by hard agglomeration of nanoparticles. Furthermore, the dense, non-porous silica shell completely blocks the poisoning pathway of polydopamine to the platinum catalyst, ensuring the complete progress of the subsequent curing reaction and forming a uniform and complete three-dimensional cross-linked network. This avoids the problems of insufficient matrix strength and accelerated wear caused by incomplete curing. Through surface grafting of vinyltrimethoxysilane, high-density vinyl active sites are anchored on the surface of the core-shell filler. During the final hydrosilylation curing process, the vinyl groups on the filler surface can undergo an addition reaction with hydrogen-containing silicone oil, permanently weaving the rigid filler into the three-dimensional cross-linked network of the silicone matrix in the form of covalent bonds. This constructs a continuous stress transfer network of matrix, covalent bonds, and rigid filler, which can efficiently transfer and disperse the local stress generated during friction through the rigid filler, inhibit the generation and propagation of microcracks on the silicone surface, and significantly reduce the fatigue wear of the material.

[0006] As a preference, in step (3), the mass ratio of the first dry base adhesive to the dehydrated fluorosilane is 90:(7-9).

[0007] As a preference, in step (4), the mass ratio of nanodiamond to dopamine hydrochloride is 8:(2-3).

[0008] As a preference, in step (5), the mass ratio of PDA@ND powder to tetraethyl orthosilicate is 5:(13-16).

[0009] As a preference, in step (6), the mass ratio of PDA@ND@SiO2 dense core-shell filler to vinyltrimethoxysilane is 4:(1-2).

[0010] As a preference, in step (6), the mass ratio of PDA@ND@SiO2 dense core-shell filler to octyltriethoxysilane is 4:(0.5-1.0).

[0011] As a preference, in step (7), the mass ratio of the fluorinated modified liquid silicone matrix, the modified wear-resistant filler, and the vinyl MQ silicone resin is 98:(3-5):(3-5).

[0012] The present invention found in experiments that due to the huge stiffness difference between the high-hardness nanodiamond and silica shell and the extremely soft fluorinated liquid silicone matrix, and the extremely low surface energy of the fluorinated matrix, the polar silica shell will instinctively repel the microscopic wetting, resulting in poor microscopic wetting. This dual defect makes it impossible for frictional stress to be smoothly transmitted, but instead it is all concentrated on the thin interfacial covalent bonds, which eventually leads to interfacial tearing and filler detachment, affecting the improvement of the wear resistance of silicone. To solve this technical problem, this invention introduces octyltriethoxysilane and vinyl MQ silicone resin, constructing a stepped modulus transition zone at the interface through the synergistic assembly of the two substances. The core principle is as follows: First, co-grafting treatment is performed on the filler surface. The lipophilic, flexible, long aliphatic chain with eight carbon atoms in octyltriethoxysilane neutralizes the polarity of the silica shell, completely overcoming the "fluorine repulsion" effect of the fluorine-containing matrix, achieving efficient and dense wetting of the filler by the base resin. Simultaneously, this flexible long chain acts as a molecular-level spring damper under stress, effectively absorbing and dissipating instantaneous frictional impact energy. Then, a semi-rigid three-dimensional network reinforcing agent, vinyl MQ silicone resin, with a size of 1-3 nm, is introduced into the matrix. It automatically accumulates on the octyl... Around the long-chain affinity-treated filler, and during the final hydrosilylation curing process, it not only covalently crosslinks with the matrix and filler through its own vinyl groups, but also forms a deep physical entanglement with the octyl flexible long chains on the filler surface. The synergistic effect of these two substances constructs a modulus gradient band at the microscopic interface, consisting of a rigid diamond core, a hard silica shell, a flexible octyl buffer spring, a semi-rigid MQ resin transition bridge, and a soft, low-friction fluorinated matrix. This allows high-frequency frictional stress to be smoothly reduced and dissipated layer by layer like waves, completely eliminating interfacial stress concentration points. This not only increases the tear fatigue life of the interfacial covalent bonds by several times, but also further improves the overall dynamic wear resistance of liquid silicone without increasing high costs.

[0013] As a preference, in step (8), the mass ratio of the second dry base adhesive, the hydrogen-containing silicone oil, and 3-methyl-1-butyn-3-ol is 80:(18-20):(0.1-0.2).

[0014] As a preference, in step (9), the mass ratio of component A to component B is 1:(0.9 to 1.1).

[0015] A medical-grade liquid silicone is prepared by the method described above.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. Low-friction perfluoroalkyl groups are covalently grafted onto the silicone backbone, preventing the migration of additives and reducing the coefficient of friction and adhesive wear from the source.

[0017] 2. A dense structure with nanodiamond as the core and silica as the shell is adopted to achieve monodispersion and isolate catalyst poisoning; the filler is covalently bonded into the cross-linked network through surface grafting, which can efficiently disperse friction load.

[0018] 3. By utilizing the synergistic effect of octyl flexible long chains and semi-rigid MQ resin, a modulus transition zone is constructed between the filler and the matrix, which dissipates impact energy, improves the interfacial tear fatigue life, and further optimizes dynamic wear resistance. Attached Figure Description

[0019] Figure 1 This is a low-magnification SEM image of the liquid silicone surface prepared in Example 1 of the present invention.

[0020] Figure 2 This is a high-magnification SEM image of the surface of the liquid silicone prepared in Example 1 of the present invention.

[0021] Figure 3 This is the XPS spectrum of the liquid silicone surface prepared in Example 1 of the present invention.

[0022] Figure 4 The image shows the XRD pattern of the liquid silica gel prepared in Example 1 of this invention. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1 A method for preparing medical-grade liquid silicone includes the following steps: (1) Place 200 parts by weight of polydimethylsiloxane with vinyl-terminated end and vinyl-containing side chains (total vinyl content 1.2wt%) into a vacuum drying oven, set the temperature to 110℃ and the vacuum degree to -0.095MPa, and dry for 3 hours. After drying, cool to room temperature under nitrogen protection, weigh out 90 parts by weight as the first dry base adhesive, and weigh out 80 parts by weight as the second dry base adhesive for later use.

[0025] (2) Take 8 parts by weight of 1H,1H,2H,2H-perfluorodecyldimethylsilane, add 0.8 parts by weight of 4A molecular sieve that has been activated at 120℃, seal and let stand at room temperature at 25℃ for 24h to dehydrate, filter to remove molecular sieve, and obtain dehydrated fluorosilane.

[0026] (3) In a closed reactor under nitrogen protection, add 90 parts by weight of the first dry base adhesive and 8.5 parts by weight of dehydrated fluorosilane, and then add 0.1 parts by weight of platinum-vinylsiloxane complex catalyst. Set the temperature to 80°C and the stirring speed to 400 rpm, and keep the reaction at this temperature for 6 hours. After the reaction is completed, raise the temperature of the system to 100°C, turn on the vacuum pump to evacuate the vacuum to -0.095 MPa, and continue to volatilize for 1 hour to remove unreacted monomers. Then cool down to room temperature and weigh 98 parts by weight as fluorine-modified liquid silica matrix for later use.

[0027] (4) Take 8 parts by weight of nanodiamond with a particle size of 40 nm, add it to a mixed solvent of anhydrous ethanol and deionized water in a volume ratio of 3:1, stir mechanically for 10 min and sonicate in an ice-water bath for 45 min, then centrifuge at 8000 rpm to remove the supernatant, and redisperse the substrate in 0.05 mol / L Tris-HCl aqueous buffer (pH=8.5); add 2.8 parts by weight of dopamine hydrochloride, and under open conditions with slow air circulation and complete protection from light, set the temperature at 28℃ and the stirring speed at 300 rpm for 18 h. After the reaction, centrifuge and wash, and vacuum dry at 60℃ for 12 h to obtain PDA@ND powder.

[0028] (5) Take 5 parts by weight of the above PDA@ND powder and add it to a mixture of anhydrous ethanol and deionized water in a volume ratio of 4:1. Disperse it evenly by sonication for 30 min and add ammonia water to adjust the pH to 9.5. Heat the mixture to 35°C in a sealed reactor and add anhydrous ethanol containing 15 parts by weight of tetraethyl orthosilicate at a rate of 0.8 mL / min. Keep the mixture warm and stir for 8 h. After the reaction is completed, centrifuge and wash it 4 times with anhydrous ethanol. Dry it under vacuum at 60°C for 12 h to obtain PDA@ND@SiO2 dense core-shell filler.

[0029] (6) Take 4 parts by weight of the above PDA@ND@SiO2 dense core-shell filler and add it to a mixture of anhydrous ethanol and deionized water in a volume ratio of 9:1. Add glacial acetic acid to adjust the pH to 4.5. Then add 1.8 parts by weight of vinyltrimethoxysilane and 0.9 parts by weight of octyltriethoxysilane. Heat to 60°C and stir for 6 hours. After the reaction is completed, centrifuge and wash 3 times. Dry under vacuum at 60°C for 12 hours to obtain the modified wear-resistant filler.

[0030] (7) 98 parts by weight of fluorine-modified liquid silica matrix, 4.5 parts by weight of modified wear-resistant filler, 4.5 parts by weight of vinyl MQ silicone resin, and 0.6 parts by weight of platinum-vinylsiloxane complex catalyst were added to the mixing tank of a planetary mixer with rotation and revolution. The mixer was set to rotate at 2000 rpm and revolve at 800 rpm for 5 min. Then it was ground for 3 passes by a three-roll mill. After grinding, the mixing tank was returned and degassed at 1000 rpm and -0.095 MPa vacuum for 3 min to obtain component A.

[0031] (8) In another clean mixing tank, add 80 parts by weight of the reserved second dry base adhesive, add 0.18 parts by weight of 3-methyl-1-butyn-3-ol and mix manually until uniform. Then add 19.5 parts by weight of hydrogen-containing silicone oil and mix under normal pressure for 2 minutes in a planetary mixer to obtain component B.

[0032] (9) Weigh 100 parts by weight of component A and 105 parts by weight of component B, combine them into a vacuum planetary tank, set the rotation speed to 1500 rpm and the vacuum degree to -0.095 MPa, stir and mix and degas for 3 min; inject the uniformly mixed material into a polytetrafluoroethylene mold, place it in a flat vulcanizing machine, and hot press and initially cure for 10 min at 5 MPa pressure and 110℃, then raise the temperature to 150℃ for secondary curing for 40 min, cool down and open the mold, and place the product in a 120℃ vacuum oven for post-treatment for 2 h to obtain medical liquid silicone.

[0033] Example 2 A method for preparing medical-grade liquid silicone includes the following steps: (1) Place 200 parts by weight of polydimethylsiloxane with vinyl-terminated end and vinyl-containing side chains (total vinyl content 1.2wt%) into a vacuum drying oven, set the temperature to 110℃ and the vacuum degree to -0.095MPa, and dry for 3 hours. After drying, cool to room temperature under nitrogen protection, weigh out 90 parts by weight as the first dry base adhesive, and weigh out 80 parts by weight as the second dry base adhesive for later use.

[0034] (2) Take 8 parts by weight of 1H,1H,2H,2H-perfluorodecyldimethylsilane, add 0.8 parts by weight of 4A molecular sieve that has been activated at 120℃, seal and let stand at room temperature at 25℃ for 24h to dehydrate, filter to remove molecular sieve, and obtain dehydrated fluorosilane.

[0035] (3) In a closed reactor under nitrogen protection, add 90 parts by weight of the first dry base adhesive and 7.5 parts by weight of dehydrated fluorosilane, and then add 0.1 parts by weight of platinum-vinylsiloxane complex catalyst. Set the temperature to 80°C and the stirring speed to 400 rpm, and keep the reaction at this temperature for 6 hours. After the reaction is completed, raise the temperature of the system to 100°C, turn on the vacuum pump to draw the vacuum to -0.095 MPa, and continue to volatilize for 1 hour to remove unreacted monomers. Then cool down to room temperature and weigh 98 parts by weight as fluorine-modified liquid silica matrix for later use.

[0036] (4) Take 8 parts by weight of nanodiamond with a particle size of 40 nm, add it to a mixed solvent of anhydrous ethanol and deionized water in a volume ratio of 3:1, stir mechanically for 10 min and sonicate in an ice-water bath for 45 min, then centrifuge at 8000 rpm to remove the supernatant, and redisperse the substrate in 0.05 mol / L Tris-HCl aqueous buffer (pH=8.5); add 2.3 parts by weight of dopamine hydrochloride, and under open conditions with slow air circulation and complete protection from light, set the temperature at 28℃ and the stirring speed at 300 rpm for 18 h. After the reaction, centrifuge and wash, and vacuum dry at 60℃ for 12 h to obtain PDA@ND powder.

[0037] (5) Take 5 parts by weight of the above PDA@ND powder and add it to a mixture of anhydrous ethanol and deionized water in a volume ratio of 4:1. Disperse it evenly by sonication for 30 min and add ammonia water to adjust the pH to 9.5. Heat the mixture to 35°C in a sealed reactor and add anhydrous ethanol mixture containing 14 parts by weight of tetraethyl orthosilicate at a rate of 0.8 mL / min. Keep the mixture warm and stir for 8 h. After the reaction is completed, centrifuge and wash it 4 times with anhydrous ethanol. Dry it under vacuum at 60°C for 12 h to obtain PDA@ND@SiO2 dense core-shell filler.

[0038] (6) Take 4 parts by weight of the above PDA@ND@SiO2 dense core-shell filler and add it to a mixture of anhydrous ethanol and deionized water in a volume ratio of 9:1. Add glacial acetic acid to adjust the pH to 4.5. Then add 1.2 parts by weight of vinyltrimethoxysilane and 0.6 parts by weight of octyltriethoxysilane. Heat to 60°C and stir for 6 hours. After the reaction is completed, centrifuge and wash 3 times. Dry under vacuum at 60°C for 12 hours to obtain the modified wear-resistant filler.

[0039] (7) 98 parts by weight of fluorine-modified liquid silica matrix, 3.5 parts by weight of modified wear-resistant filler, 3.5 parts by weight of vinyl MQ silicone resin, and 0.6 parts by weight of platinum-vinylsiloxane complex catalyst were added to the mixing tank of a planetary mixer with rotation and revolution. The mixer was set to rotate at 2000 rpm and revolve at 800 rpm for 5 min. Then it was ground for 3 passes by a three-roll mill. After grinding, the mixing tank was returned and degassed at 1000 rpm and -0.095 MPa vacuum for 3 min to obtain component A.

[0040] (8) In another clean mixing tank, add 80 parts by weight of the reserved second dry base adhesive, add 0.12 parts by weight of 3-methyl-1-butyn-3-ol and mix manually until uniform. Then add 18.5 parts by weight of hydrogen-containing silicone oil and mix under normal pressure for 2 minutes in a planetary mixer to obtain component B.

[0041] (9) Weigh 100 parts by weight of component A and 95 parts by weight of component B, combine them into a vacuum planetary tank, set the rotation speed to 1500 rpm and the vacuum degree to -0.095 MPa, stir and mix and degas for 3 min; inject the uniformly mixed material into a polytetrafluoroethylene mold, place it in a flat vulcanizing machine, and hot press and initially cure for 10 min at 5 MPa pressure and 110℃, then raise the temperature to 150℃ for secondary curing for 40 min, cool down and open the mold, and place the product in a 120℃ vacuum oven for post-treatment for 2 h to obtain medical liquid silicone.

[0042] Example 3 A method for preparing medical-grade liquid silicone includes the following steps: (1) Place 200 parts by weight of polydimethylsiloxane with vinyl-terminated end and vinyl-containing side chains (total vinyl content 1.2wt%) into a vacuum drying oven, set the temperature to 110℃ and the vacuum degree to -0.095MPa, and dry for 3 hours. After drying, cool to room temperature under nitrogen protection, weigh out 90 parts by weight as the first dry base adhesive, and weigh out 80 parts by weight as the second dry base adhesive for later use.

[0043] (2) Take 8 parts by weight of 1H,1H,2H,2H-perfluorodecyldimethylsilane, add 0.8 parts by weight of 4A molecular sieve that has been activated at 120℃, seal and let stand at room temperature at 25℃ for 24h to dehydrate, filter to remove molecular sieve, and obtain dehydrated fluorosilane.

[0044] (3) In a closed reactor under nitrogen protection, add 90 parts by weight of the first dry base adhesive and 8 parts by weight of dehydrated fluorosilane, and then add 0.1 parts by weight of platinum-vinylsiloxane complex catalyst. Set the temperature to 80°C and the stirring speed to 400 rpm, and keep the reaction at this temperature for 6 hours. After the reaction is completed, raise the temperature of the system to 100°C, turn on the vacuum pump to evacuate the vacuum to -0.095 MPa, and continue to volatilize for 1 hour to remove unreacted monomers. Then cool down to room temperature and weigh 98 parts by weight as fluorine-modified liquid silica matrix for later use.

[0045] (4) Take 8 parts by weight of nanodiamond with a particle size of 40 nm, add it to a mixed solvent of anhydrous ethanol and deionized water in a volume ratio of 3:1, stir mechanically for 10 min and sonicate in an ice-water bath for 45 min, then centrifuge at 8000 rpm to remove the supernatant, and redisperse the substrate in 0.05 mol / L Tris-HCl aqueous buffer (pH=8.5); add 2.5 parts by weight of dopamine hydrochloride, and under open conditions with slow air circulation and complete protection from light, set the temperature at 28℃ and the stirring speed at 300 rpm for 18 h. After the reaction, centrifuge and wash, and vacuum dry at 60℃ for 12 h to obtain PDA@ND powder.

[0046] (5) Take 5 parts by weight of the above PDA@ND powder and add it to a mixture of anhydrous ethanol and deionized water in a volume ratio of 4:1. Disperse it evenly by sonication for 30 min and add ammonia water to adjust the pH to 9.5. Heat the mixture to 35°C in a sealed reactor and add anhydrous ethanol mixture containing 14.5 parts by weight of tetraethyl orthosilicate at a rate of 0.8 mL / min. Keep the mixture warm and stir for 8 h. After the reaction is completed, centrifuge and wash it 4 times with anhydrous ethanol. Dry it under vacuum at 60°C for 12 h to obtain PDA@ND@SiO2 dense core-shell filler.

[0047] (6) Take 4 parts by weight of the above PDA@ND@SiO2 dense core-shell filler and add it to a mixture of anhydrous ethanol and deionized water in a volume ratio of 9:1. Add glacial acetic acid to adjust the pH to 4.5. Then add 1.5 parts by weight of vinyltrimethoxysilane and 0.8 parts by weight of octyltriethoxysilane. Heat to 60°C and stir for 6 hours. After the reaction is completed, centrifuge and wash 3 times. Dry under vacuum at 60°C for 12 hours to obtain the modified wear-resistant filler.

[0048] (7) 98 parts by weight of fluorine-modified liquid silica matrix, 4 parts by weight of modified wear-resistant filler, 4 parts by weight of vinyl MQ silicone resin, and 0.6 parts by weight of platinum-vinylsiloxane complex catalyst were added to the mixing tank of a planetary mixer with rotation and revolution. The mixer was set to rotate at 2000 rpm and revolve at 800 rpm for 5 min. Then it was ground for 3 passes by a three-roll mill. After grinding, the mixing tank was returned and degassed at 1000 rpm and -0.095 MPa vacuum for 3 min to obtain component A.

[0049] (8) In another clean mixing tank, add 80 parts by weight of the reserved second dry base adhesive, add 0.15 parts by weight of 3-methyl-1-butyn-3-ol and mix manually until uniform. Then add 19 parts by weight of hydrogen-containing silicone oil and mix under normal pressure for 2 minutes in a planetary mixer to obtain component B.

[0050] (9) Weigh 100 parts by weight of component A and 100 parts by weight of component B, combine them into a vacuum planetary tank, set the rotation speed to 1500 rpm and the vacuum degree to -0.095 MPa, stir and mix and degas for 3 min; inject the uniformly mixed material into a polytetrafluoroethylene mold, place it in a flat vulcanizing machine, and hot press and initially cure for 10 min at 5 MPa pressure and 110℃, then raise the temperature to 150℃ for secondary curing for 40 min, cool down and open the mold, and place the product in a 120℃ vacuum oven for post-treatment for 2 h to obtain medical liquid silicone.

[0051] Example 4 A method for preparing medical-grade liquid silicone includes the following steps: (1) Place 200 parts by weight of polydimethylsiloxane with vinyl-terminated end and vinyl-containing side chains (total vinyl content 1.2wt%) into a vacuum drying oven, set the temperature to 110℃ and the vacuum degree to -0.095MPa, and dry for 3 hours. After drying, cool to room temperature under nitrogen protection, weigh out 90 parts by weight as the first dry base adhesive, and weigh out 80 parts by weight as the second dry base adhesive for later use.

[0052] (2) Take 8 parts by weight of 1H,1H,2H,2H-perfluorodecyldimethylsilane, add 0.8 parts by weight of 4A molecular sieve that has been activated at 120℃, seal and let stand at room temperature at 25℃ for 24h to dehydrate, filter to remove molecular sieve, and obtain dehydrated fluorosilane.

[0053] (3) In a closed reactor under nitrogen protection, add 90 parts by weight of the first dry base adhesive and 9 parts by weight of dehydrated fluorosilane, and then add 0.1 parts by weight of platinum-vinylsiloxane complex catalyst. Set the temperature to 80°C and the stirring speed to 400 rpm, and keep the reaction at this temperature for 6 hours. After the reaction is completed, raise the temperature of the system to 100°C, turn on the vacuum pump to evacuate the vacuum to -0.095 MPa, and continue to volatilize for 1 hour to remove unreacted monomers. Then cool down to room temperature and weigh 98 parts by weight as fluorine-modified liquid silica matrix for later use.

[0054] (4) Take 8 parts by weight of nanodiamond with a particle size of 40 nm, add it to a mixed solvent of anhydrous ethanol and deionized water in a volume ratio of 3:1, stir mechanically for 10 min and sonicate in an ice-water bath for 45 min, then centrifuge at 8000 rpm to remove the supernatant, and redisperse the substrate in 0.05 mol / L Tris-HCl aqueous buffer (pH=8.5); add 3 parts by weight of dopamine hydrochloride, and under open conditions with slow air circulation and complete protection from light, set the temperature at 28℃ and the stirring speed at 300 rpm for 18 h. After the reaction, centrifuge and wash, and vacuum dry at 60℃ for 12 h to obtain PDA@ND powder.

[0055] (5) Take 5 parts by weight of the above PDA@ND powder and add it to a mixture of anhydrous ethanol and deionized water in a volume ratio of 4:1. Disperse it evenly by sonication for 30 min and add ammonia water to adjust the pH to 9.5. Heat the mixture to 35°C in a sealed reactor and add anhydrous ethanol containing 16 parts by weight of tetraethyl orthosilicate dropwise at a rate of 0.8 mL / min. Keep the mixture warm and stir for 8 h. After the reaction is completed, centrifuge and wash it 4 times with anhydrous ethanol. Dry it under vacuum at 60°C for 12 h to obtain PDA@ND@SiO2 dense core-shell filler.

[0056] (6) Take 4 parts by weight of the above PDA@ND@SiO2 dense core-shell filler and add it to a mixture of anhydrous ethanol and deionized water in a volume ratio of 9:1. Add glacial acetic acid to adjust the pH to 4.5. Then add 2 parts by weight of vinyltrimethoxysilane and 1.0 parts by weight of octyltriethoxysilane. Heat to 60°C and stir for 6 hours. After the reaction is completed, centrifuge and wash 3 times. Dry under vacuum at 60°C for 12 hours to obtain the modified wear-resistant filler.

[0057] (7) 98 parts by weight of fluorine-modified liquid silica matrix, 5 parts by weight of modified wear-resistant filler, 5 parts by weight of vinyl MQ silicone resin, and 0.6 parts by weight of platinum-vinylsiloxane complex catalyst were added to the mixing tank of a planetary mixer with rotation and revolution. The mixer was set to rotate at 2000 rpm and revolve at 800 rpm for 5 min. Then it was ground for 3 passes by a three-roll mill. After grinding, the mixing tank was returned and degassed at 1000 rpm and -0.095 MPa vacuum for 3 min to obtain component A.

[0058] (8) In another clean mixing tank, add 80 parts by weight of the reserved second dry base adhesive, add 0.2 parts by weight of 3-methyl-1-butyn-3-ol and mix manually until uniform, then add 20 parts by weight of hydrogen-containing silicone oil, and mix under normal pressure for 2 minutes in a planetary mixer to obtain component B.

[0059] (9) Weigh 100 parts by weight of component A and 110 parts by weight of component B, combine them into a vacuum planetary tank, set the rotation speed to 1500 rpm and the vacuum degree to -0.095 MPa, stir and mix and degas for 3 min; inject the uniformly mixed material into a polytetrafluoroethylene mold, place it in a flat vulcanizing machine, and hot press and initially cure for 10 min at 5 MPa pressure and 110℃, then raise the temperature to 150℃ for secondary curing for 40 min, cool down and open the mold, and place the product in a 120℃ vacuum oven for post-treatment for 2 h to obtain medical liquid silicone.

[0060] Example 5 A method for preparing medical-grade liquid silicone includes the following steps: (1) Place 200 parts by weight of polydimethylsiloxane with vinyl-terminated end and vinyl-containing side chains (total vinyl content 1.2wt%) into a vacuum drying oven, set the temperature to 110℃ and the vacuum degree to -0.095MPa, and dry for 3 hours. After drying, cool to room temperature under nitrogen protection, weigh out 90 parts by weight as the first dry base adhesive, and weigh out 80 parts by weight as the second dry base adhesive for later use.

[0061] (2) Take 8 parts by weight of 1H,1H,2H,2H-perfluorodecyldimethylsilane, add 0.8 parts by weight of 4A molecular sieve that has been activated at 120℃, seal and let stand at room temperature at 25℃ for 24h to dehydrate, filter to remove molecular sieve, and obtain dehydrated fluorosilane.

[0062] (3) In a closed reactor under nitrogen protection, add 90 parts by weight of the first dry base adhesive and 7 parts by weight of dehydrated fluorosilane, and then add 0.1 parts by weight of platinum-vinylsiloxane complex catalyst. Set the temperature to 80°C and the stirring speed to 400 rpm, and keep the reaction at this temperature for 6 hours. After the reaction is completed, raise the temperature of the system to 100°C, turn on the vacuum pump to evacuate the vacuum to -0.095 MPa, and continue to volatilize for 1 hour to remove unreacted monomers. Then cool down to room temperature and weigh 98 parts by weight as fluorine-modified liquid silica matrix for later use.

[0063] (4) Take 8 parts by weight of nanodiamond with a particle size of 40 nm, add it to a mixed solvent of anhydrous ethanol and deionized water in a volume ratio of 3:1, stir mechanically for 10 min and sonicate in an ice water bath for 45 min, then centrifuge at 8000 rpm to remove the supernatant, and redisperse the substrate in 0.05 mol / L Tris-HCl aqueous buffer (pH=8.5); add 2 parts by weight of dopamine hydrochloride, and under open conditions with slow air circulation and complete protection from light, set the temperature at 28℃ and the stirring speed at 300 rpm for 18 h. After the reaction, centrifuge and wash, and vacuum dry at 60℃ for 12 h to obtain PDA@ND powder.

[0064] (5) Take 5 parts by weight of the above PDA@ND powder and add it to a mixture of anhydrous ethanol and deionized water in a volume ratio of 4:1. Disperse it evenly by sonication for 30 min and add ammonia water to adjust the pH to 9.5. Heat the mixture to 35°C in a sealed reactor and add anhydrous ethanol containing 13 parts by weight of tetraethyl orthosilicate dropwise at a rate of 0.8 mL / min. Keep the mixture warm and stir for 8 h. After the reaction is completed, centrifuge and wash it 4 times with anhydrous ethanol. Dry it under vacuum at 60°C for 12 h to obtain PDA@ND@SiO2 dense core-shell filler.

[0065] (6) Take 4 parts by weight of the above PDA@ND@SiO2 dense core-shell filler and add it to a mixture of anhydrous ethanol and deionized water in a volume ratio of 9:1. Add glacial acetic acid to adjust the pH to 4.5. Then add 1 part by weight of vinyltrimethoxysilane and 0.5 parts by weight of octyltriethoxysilane. Heat to 60°C and stir for 6 hours. After the reaction is completed, centrifuge and wash 3 times. Dry under vacuum at 60°C for 12 hours to obtain the modified wear-resistant filler.

[0066] (7) 98 parts by weight of fluorine-modified liquid silica matrix, 3 parts by weight of modified wear-resistant filler, 3 parts by weight of vinyl MQ silicone resin, and 0.6 parts by weight of platinum-vinylsiloxane complex catalyst were added to the mixing tank of a planetary mixer with rotation and revolution. The mixer was set to rotate at 2000 rpm and revolve at 800 rpm for 5 min. Then it was ground for 3 passes by a three-roll mill. After grinding, the mixing tank was returned and degassed at 1000 rpm and -0.095 MPa vacuum for 3 min to obtain component A.

[0067] (8) In another clean mixing tank, add 80 parts by weight of the reserved second dry base adhesive, add 0.1 parts by weight of 3-methyl-1-butyn-3-ol and mix manually until uniform, then add 18 parts by weight of hydrogen-containing silicone oil, and mix under normal pressure for 2 minutes in a planetary mixer to obtain component B.

[0068] (9) Weigh 100 parts by weight of component A and 90 parts by weight of component B, combine them into a vacuum planetary tank, set the rotation speed to 1500 rpm and the vacuum degree to -0.095 MPa, stir and mix and degas for 3 min; inject the uniformly mixed material into a polytetrafluoroethylene mold, place it in a flat vulcanizing machine, and hot press and initially cure for 10 min at 5 MPa pressure and 110℃, then raise the temperature to 150℃ for secondary curing for 40 min, cool down and open the mold, and place the product in a 120℃ vacuum oven for post-treatment for 2 h to obtain medical liquid silicone.

[0069] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the fluorine-modified liquid silica matrix in step 7 is replaced with an equal mass of dried polydimethylsiloxane with vinyl-terminated end groups and vinyl-containing side chains.

[0070] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that the modified wear-resistant filler in step 7 is replaced with an equal mass of nanodiamond.

[0071] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that octyltriethoxysilane is not added in step 6, and vinyl MQ silicone resin is not added in step 7.

[0072] Comparative Example 4: The difference between Comparative Example 4 and Example 1 is that octyltriethoxysilane is not added in step 6.

[0073] Comparative Example 5: The difference between Comparative Example 5 and Example 1 is that vinyl MQ silicone resin is not added in step 6.

[0074] Performance testing: 1. Abrasion Resistance Test: The test was conducted according to GB / T 1689-2014 "Determination of Abrasion Resistance of Vulcanized Rubber (using Akron Abrasion Tester)". The test samples were prepared as cylindrical specimens with a diameter of 16.0 mm ± 0.2 mm and a thickness of 8.0 mm ± 0.2 mm. After conditioning in an environment of 23℃ and 50% relative humidity for 24 hours, the specimens were mounted on the Akron abrasion tester. The grinding wheel speed was set to 76 r / min, the specimen tilt angle to 15°, and the load to 26.7 N. After 1000 revolutions of pre-grinding, the initial mass of the specimen was weighed. After 1.61 km (4000 revolutions) of formal abrasion, the mass of the specimen was weighed again. The abrasion volume was calculated based on the specimen density. The abrasion resistance of the sample was finally characterized by the wear rate. Each group of specimens was tested in parallel three times, and the arithmetic mean was taken as the final result. The test results are shown in Table 1.

[0075] 2. Dynamic Friction Coefficient Test: The test was conducted according to GB / T 10006-2021 "Determination of Friction Coefficient of Plastic Films and Sheets". The test sample was cut into rectangular specimens of 120mm × 60mm with a thickness of 2mm. Medical-grade 304 stainless steel was used as the friction pair. In an environment of 23℃ and 50% relative humidity, a friction coefficient tester was set to a test speed of 100mm / min and a test stroke of 70mm. The dynamic friction coefficient between the sample and the stainless steel plate was recorded. Each group of samples was tested in parallel five times. After removing the first and last abnormal data, the arithmetic mean was taken as the final result. The test results are shown in Table 1.

[0076] 3. Tensile Strength and Elongation at Break Test: Tests were conducted according to GB / T 528-2009 "Determination of Tensile Properties of Vulcanized Rubber or Thermoplastic Rubber". The test samples were molded into type 1 dumbbell-shaped specimens with a thickness of 2.0 mm ± 0.2 mm. After conditioning for 24 hours at 23℃ and 50% relative humidity, the tensile strength and elongation at break of the specimens were tested using a universal electronic tensile testing machine with a tensile speed of 500 mm / min. Each group of specimens was tested in parallel for 5 times, and the arithmetic mean was taken as the final result. The test results are shown in Table 1.

[0077] 4. Shore A Hardness Test: The test was conducted according to ASTM D2240-2021, "Standard Test Method for Hardness of Rubber". The test samples were stacked to a thickness of not less than 6 mm, ensuring a smooth surface free of bubbles and mechanical defects. After conditioning for 1 hour in an environment of 23℃ and 50% relative humidity, five points were tested at different locations on the sample using a Shore A hardness tester, with a minimum distance of 6 mm between each test point. The arithmetic mean was taken as the final hardness result. The test results are shown in Table 1.

[0078] Table 1:

[0079] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing medical-grade liquid silicone, characterized in that, Includes the following steps: (1) Polydimethylsiloxane with vinyl-terminated end and vinyl-containing side chains is vacuum dried to obtain a dry base adhesive, and then divided into two portions of dry base adhesive. (2) Dehydrate 1H,1H,2H,2H-perfluorodecyldimethylsilane to obtain dehydrated fluorosilane; (3) Under the protection of inert gas, the first dry base glue obtained in step (1) is added to dehydrated fluorosilane in the presence of platinum-vinylsiloxane complex catalyst. After the reaction, the unreacted monomers are removed by vacuum to obtain fluorine-modified liquid silica matrix. (4) Disperse nanodiamonds in a solvent, add dopamine hydrochloride to carry out a polymerization reaction, and form a polydopamine coating layer on the surface of nanodiamonds to obtain PDA@ND powder; (5) A silica layer is coated on the outside of PDA@ND powder by hydrolysis and polycondensation reaction of tetraethyl orthosilicate to obtain PDA@ND@SiO2 dense core-shell filler; (6) Vinyltrimethoxysilane and octyltriethoxysilane were grafted onto the surface of PDA@ND@SiO2 dense core-shell filler to obtain modified wear-resistant filler; (7) Fluorine-modified liquid silica matrix, modified wear-resistant filler, vinyl MQ silicone resin and platinum-vinylsiloxane complex catalyst are mixed, and then ground, dispersed and degassed to obtain component A; (8) Mix the second portion of the dried base adhesive reserved in step (1), the hydrogen-containing silicone oil, and 3-methyl-1-butyn-3-ol to obtain component B; (9) Mix component A and component B evenly, degas and heat to cure, and you will get the product.

2. The method for preparing medical liquid silicone according to claim 1, characterized in that, In step (3), the mass ratio of the first dry base adhesive to the dehydrated fluorosilane is 90:(7-9).

3. The method for preparing medical liquid silicone according to claim 1, characterized in that, In step (4), the mass ratio of nanodiamond to dopamine hydrochloride is 8:(2-3).

4. The method for preparing medical liquid silicone according to claim 1, characterized in that, In step (5), the mass ratio of PDA@ND powder to tetraethyl orthosilicate is 5:(13-16).

5. The method for preparing medical liquid silicone according to claim 1, characterized in that, In step (6), the mass ratio of PDA@ND@SiO2 dense core-shell filler to vinyltrimethoxysilane is 4:(1-2).

6. The method for preparing medical liquid silicone according to claim 1, characterized in that, In step (6), the mass ratio of PDA@ND@SiO2 dense core-shell filler to octyltriethoxysilane is 4:(0.5~1.0).

7. The method for preparing medical liquid silicone according to claim 1, characterized in that, In step (7), the mass ratio of the fluorine-modified liquid silicone matrix, the modified wear-resistant filler, and the vinyl MQ silicone resin is 98:(3-5):(3-5).

8. The method for preparing medical liquid silicone according to claim 1, characterized in that, In step (8), the mass ratio of the second dry base adhesive, hydrogen-containing silicone oil, and 3-methyl-1-butyn-3-ol is 80:(18-20):(0.1-0.2).

9. The method for preparing medical liquid silicone according to claim 1, characterized in that, In step (9), the mass ratio of component A to component B is 1:(0.9 to 1.1).

10. A medical liquid silicone, characterized in that, It is prepared by the method described in any one of claims 1-9 above.

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