Liquid silicone rubber and method of making

Abstract

The application belongs to the technical field of organic silicon, and discloses a kind of liquid silicone rubber and preparation method.The raw materials of liquid silicone rubber in the application include vinyl polysiloxane, nano titanium dioxide particles, hydrogenated polysiloxane, silicone resin, composite antibacterial particles and structure modifier.The composite antibacterial particles are prepared from black phosphorus nanosheet, silver nitrate and long-chain alkyl acrylate.The structure modifier is imidazole group and / or pyridine group modified siloxane.The liquid silicone rubber prepared in the application has long-lasting and efficient antibacterial performance by adding long-chain alkyl acrylate modified black phosphorus nanosheet-nano silver composite particles as composite antibacterial ions.The heat aging resistance and ultraviolet aging resistance of the silicone rubber are improved by adding modified nano titanium dioxide particles.In addition, the liquid silicone rubber in the application has good biocompatibility, and can be widely used to prepare silicone rubber products or medical silicone rubber that are in close contact with human body.

Description

Technical Field

[0001] This invention relates to the field of organosilicon technology, and in particular to a liquid silicone rubber and its preparation method. Background Technology

[0002] Liquid silicone rubber is classified into condensation-type and addition-type liquid silicone rubber according to its crosslinking mechanism. Currently, addition-type liquid silicone rubber is more widely used, as it crosslinks through a hydrosilylation mechanism and does not produce byproducts during vulcanization. Liquid silicone rubber is widely used in aerospace, automotive, shipbuilding, photovoltaic power, and medical fields, becoming one of the fundamental materials for improving the overall performance of products in many manufacturing sectors. In the medical field, liquid silicone rubber is suitable for making products of various shapes, meeting the application requirements of various medical devices and their components. It is mainly used in Class II medical devices such as medical catheters, breathing masks, and laryngeal masks for anesthesia, as well as Class III medical devices such as immediate-puncture artificial blood vessels and implantable artificial prostheses. At the same time, there are higher requirements for the performance of liquid silicone rubber, including higher requirements for its resistance to disinfection, anti-aging, breathability, hydrophobicity, and biocompatibility. Summary of the Invention

[0003] The main objective of this invention is to develop a liquid silicone rubber and its preparation method. The liquid silicone rubber obtained has a good antibacterial effect and is not prone to aging after multiple high-temperature sterilizations or ultraviolet sterilizations, thus meeting the requirements for use in high-end liquid silicone products or medical silicone devices.

[0004] To achieve the above objectives, the present invention provides a liquid silicone rubber comprising the following raw materials in parts by weight: vinyl polysiloxane: 150-200 parts; nano titanium dioxide particles: 15-25 parts; hydrogenated polysiloxane: 5-15 parts; MQ silicone resin: 30-50 parts; composite antibacterial particles: 8-18 parts; structural modifier: 2-5 parts; catalyst: 0.6-2.4 parts; inhibitor: 0.1-1 part; wherein the composite antibacterial particles are prepared from black phosphorus nanosheets, silver nitrate, and long-chain alkyl acrylates; and the structural modifier is an imidazole- and / or pyridinyl-modified siloxane.

[0005] In one embodiment, the method for preparing the composite antibacterial particles includes the following steps:

[0006] The pH of the black phosphorus nanosheet dispersion was adjusted to approximately 5-6. Silver nitrate solution was added dropwise while stirring, followed by sodium citrate solution. The mixture was reacted at 60-65°C for 1-2 hours. The precipitate was collected, washed, and vacuum dried to obtain the antibacterial particle intermediate. Long-chain alkyl acrylate was mixed with the antibacterial particle intermediate and reacted at 70-80°C for 2-3 hours. The precipitate was collected to obtain the composite antibacterial particles.

[0007] In one embodiment, the molar ratio of the black phosphorus nanosheets to the Ag+ in the silver nitrate solution in the composite antibacterial particles is 1:(4~8).

[0008] In one embodiment, the black phosphorus nanosheet dispersion contains 3wt% to 6wt% black phosphorus nanosheets.

[0009] In one embodiment, the weight ratio of the black phosphorus nanosheets to the long-chain alkyl acrylate is 1:(3~10).

[0010] In one embodiment, the nano-titanium dioxide particles are modified nano-titanium dioxide particles; the modified nano-titanium dioxide particles are nano-silica particles coated with Schiff base compounds.

[0011] In one embodiment, the method for preparing the modified nano-titanium dioxide particles includes the following steps:

[0012] Nano-titanium dioxide particles were dispersed in a dopamine solution with a concentration of 2 mg / mL to 10 mg / mL. Sodium hydroxide was added and the pH was adjusted to approximately 9 to 11. The solution temperature was maintained at 30°C to 35°C, and the reaction was carried out for 5 to 8 hours to obtain a titanium dioxide intermediate. The dialdehyde and the titanium dioxide intermediate were dispersed in anhydrous ethanol, and the temperature was maintained at 50°C to 60°C. The reaction was carried out for 3 hours with reflux condensation during the reaction. After the reaction was completed, the solid precipitate was collected and dried under vacuum to obtain the modified nano-titanium dioxide particles.

[0013] In one embodiment, the weight ratio of the dopamine, the dialdehyde, and the nano-titanium dioxide particles is (3~5.5):(0.5~0.9):(0.6~1.5).

[0014] In one embodiment, the dialdehyde is selected from any two of glyoxal, p-hydroxybenzaldehyde, furanaldehyde, cinnamaldehyde, vanillin, o-vanillin, and salicylaldehyde.

[0015] In one embodiment, the structural modifier is selected from at least one of 2-(4-pyridylethyl)triethoxysilane, 3-pyridyltrimethoxysilane, 1-(trimethyl)-1H-imidazolium, 3-(1-imidazolium)propyltriethoxysilane, and N-imidazoliumpropyltrimethoxysilane.

[0016] In one embodiment, the inhibitor is an alkynol compound.

[0017] In one embodiment, the catalyst is a cassette catalyst.

[0018] The present invention also proposes a method for preparing the liquid silicone rubber, the method comprising the following steps:

[0019] S1. Mix 50 to 100 parts of vinyl polysiloxane with all the nano titanium dioxide particles, composite antibacterial particles and structural modifier, knead, knead at 120°C to 20°C for 10 to 20 minutes, discharge and let stand for 5 to 10 hours, then knead at room temperature for 1 to 3 hours to obtain the base rubber.

[0020] S2. Add 15 to 60 parts of vinyl polysiloxane to half of the base adhesive prepared in step S1 and disperse evenly. Then add all of the MQ silicone resin and catalyst and mix evenly. Degas under vacuum to obtain component A. Add the remaining vinyl polysiloxane to the remaining base adhesive prepared in step S1 and disperse evenly. Then add all of the hydrogenated polysiloxane and mix evenly. Add all of the inhibitor and mix. Degas under vacuum to obtain component B.

[0021] S3. Mix component A and component B, place them in a mold and vulcanize to obtain liquid silicone rubber.

[0022] In one embodiment, in step S3, the vulcanization temperature is 130℃~180℃, the vulcanization pressure is 3MPa~5MPa, and the vulcanization time is 20min~30min.

[0023] The technical solution of this invention uses long-chain alkyl acrylate-modified black phosphorus nanosheets-silver nanoparticles as composite antibacterial ions in liquid silicone rubber. The synergistic antibacterial effect of black phosphorus nanosheets and silver nanoparticles achieves a long-lasting antibacterial effect. Furthermore, due to the migration of long-chain alkyl acrylates within the silicone rubber matrix, the composite antibacterial particles can migrate and accumulate on the surface of the molded silicone rubber, allowing them to maintain good antibacterial performance even with a small addition amount. This application also incorporates Schiff base-coated nano-titanium dioxide particles, prepared by in-situ polymerization, into the silicone rubber base material. By coating the filler surface with a hydrophobic and heat-resistant layer, uniform dispersion of the titanium dioxide particles is achieved, effectively reducing the damage of ultraviolet light to the silicone rubber's properties and significantly improving its heat aging and UV aging resistance. In addition, this application employs specific structural modifiers, which on the one hand inhibit the escape of heavy metal ions or volatile organic molecules from the silicone rubber, and on the other hand restrict the movement of silicone rubber molecular chains and promote the dispersion of the two fillers within the matrix to prevent agglomeration, thereby improving the material's uniformity. The liquid silicone rubber prepared in this application has good biocompatibility and antibacterial properties, a simple preparation process, strong aging resistance, and good economic value. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. 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.

[0025] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0026] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0027] The technical problem addressed by this application is that high-end civilian silicone rubber products or medical silicone rubber products have high requirements for the antibacterial properties, low toxicity, and human biocompatibility of silicone rubber. In addition, due to sterilization requirements, silicone rubber products need to be frequently steam sterilized or ultraviolet sterilized, which will accelerate the aging of silicone rubber. Therefore, it is necessary to develop a silicone rubber with good antibacterial effect, high temperature resistance, and ultraviolet aging resistance.

[0028] To address the aforementioned technical issues, a liquid silicone rubber and its preparation method have been developed, exhibiting good bacterial inhibition effects. Furthermore, it is not prone to aging after repeated high-temperature or ultraviolet sterilization, thus meeting the requirements for use in high-end liquid silicone products or medical silicone devices.

[0029] This invention proposes a liquid silicone rubber comprising the following raw materials in parts by weight: vinyl polysiloxane: 150-200 parts; nano-titanium dioxide particles: 15-25 parts; hydrogenated polysiloxane: 5-15 parts; MQ silicone resin: 30-50 parts; composite antibacterial particles: 8-18 parts; structural modifier: 2-5 parts; catalyst: 0.6-2.4 parts; inhibitor: 0.1-1 part; wherein the composite antibacterial particles are prepared from black phosphorus nanosheets, silver nitrate, and long-chain alkyl acrylates; and the structural modifier is an imidazole- and / or pyridinyl-modified siloxane.

[0030] It should be noted that the composite antibacterial particles in this invention are black phosphorus nanosheets-silver nanocomposite particles modified with long-chain alkyl acrylates. The long-lasting antibacterial effect is achieved through the synergistic antibacterial action of black phosphorus nanosheets and silver nanosheets. Due to the repulsive effect of the polar groups of long-chain alkyl acrylates on the liquid silicone rubber base material, the composite antibacterial particles can migrate and accumulate on the surface of the prepared silicone rubber, so that the composite antibacterial particles can still exert good antibacterial performance even with a small amount added. In addition, long-chain alkyl acrylates have good hydrophobic and oleophobic properties. Combined with the dense surface of silicone rubber, the prepared liquid silicone rubber has the characteristics of stain resistance and easy cleaning. It should also be noted that the structural modifier in this invention is an imidazole- and / or pyridinyl-modified siloxane. On the one hand, the imidazole- and / or pyridinyl-modified siloxane has a strong coordination ability, which can fix heavy metal ions in silicone rubber and reduce the cytotoxicity of the prepared silicone rubber product. On the other hand, the imidazole- or pyridinyl structural modifier can chemically crosslink or physically entangle with the active groups on the surface of antibacterial composite particles, such as hydroxyl, carboxyl, long-chain alkyl groups, and active groups in the Schiff base structure on the surface of nano-titanium dioxide particles, so that the filler molecules maintain a reasonable spacing and uniform dispersion in the silicone rubber matrix, while also improving the elongation and tensile strength of liquid silicone rubber.

[0031] In one embodiment, the method for preparing the composite antibacterial particles includes the following steps:

[0032] The pH of the black phosphorus nanosheet dispersion was adjusted to approximately 5-6. Silver nitrate solution was added dropwise while stirring, followed by sodium citrate solution. The mixture was reacted at 60-65°C for 1-2 hours. The precipitate was collected, washed, and vacuum dried to obtain the antibacterial particle intermediate. Long-chain alkyl acrylate was mixed with the antibacterial particle intermediate and reacted at 70-80°C for 2-3 hours. The precipitate was collected to obtain the composite antibacterial particles.

[0033] It should be noted that the layered structure of black phosphorus nanosheets contains certain active sites on its surface, such as edge defects or functional groups, which facilitate the adsorption and reduction of metal ions. This invention uses an in-situ reduction method to load silver nanoparticles onto the surface of black phosphorus nanosheets (BPNS). To effectively avoid metal particle aggregation and improve the uniformity of loading, it is necessary to ensure that silver ions are uniformly dispersed in the black phosphorus nanosheet dispersion before the reaction, and also to ensure a mild reaction and extended reaction time. Grafting long-chain alkyl acrylates onto the surface of the black phosphorus nanosheet-silver nanoparticle composite effectively inhibits water and oxygen erosion, maintains the activity of the composite antibacterial particles, and enhances the compatibility of the composite antibacterial particles with the silicone rubber matrix.

[0034] In a preferred embodiment, the composite antibacterial particles contain black phosphorus nanosheets and Ag in the silver nitrate solution. + The molar ratio is 1:(4~8).

[0035] In a preferred embodiment, the silver nitrate solution comprises 3 wt% to 5 wt% AgNO3.

[0036] In a preferred embodiment, the black phosphorus nanosheet dispersion contains 3wt% to 6wt% black phosphorus nanosheets.

[0037] In a preferred embodiment, the weight ratio of the black phosphorus nanosheets to the long-chain alkyl acrylate is 1:(3~10).

[0038] In a preferred embodiment, the long-chain alkyl acrylate is selected from at least one of octyl acrylate, lauryl acrylate, hexadecyl acrylate, and octadecyl acrylate.

[0039] In one embodiment, the nano-titanium dioxide particles are modified nano-titanium dioxide particles; the modified nano-titanium dioxide particles are nano-titanium dioxide particles coated with Schiff base compounds.

[0040] In a preferred embodiment, the particle size of the nano-titanium dioxide particles is 30nm~100nm.

[0041] It should be noted that when silicone rubber is exposed to the outdoors or in environments containing ultraviolet radiation for a long time, the aging of the silicone rubber material will be accelerated, and it may even lead to the breakage of the molecular chain and damage to the molecular structure, thereby causing the material's performance to deteriorate or even be completely lost. In this invention, nano-titanium dioxide particles are used instead of conventional fumed silica particles. As a commonly used ultraviolet shielding agent, nano-titanium dioxide particles can effectively scatter and reflect ultraviolet rays. When the surface of the nano-titanium dioxide particles is coated with a Schiff base compound for synergistic effect, the complexity of the material surface and the change in refractive index can be further increased, thereby scattering ultraviolet rays more effectively. Schiff bases have strong antioxidant capabilities, can capture free radicals, reduce the oxidation reaction caused by ultraviolet radiation, and thus slow down the aging process of silicone rubber.

[0042] In one embodiment, the method for preparing the modified nano-titanium dioxide particles includes the following steps:

[0043] Nano-titanium dioxide particles were dispersed in a dopamine solution with a concentration of 2 mg / mL to 10 mg / mL. Sodium hydroxide was added and the pH was adjusted to approximately 9 to 11. The solution temperature was maintained at 30°C to 35°C, and the reaction was carried out for 5 to 8 hours to obtain a titanium dioxide intermediate. The dialdehyde and the titanium dioxide intermediate were dispersed in anhydrous ethanol, and the temperature was maintained at 50°C to 60°C. The reaction was carried out for 3 hours with reflux condensation during the reaction. After the reaction was completed, the solid precipitate was collected and dried under vacuum to obtain the modified nano-titanium dioxide particles.

[0044] It should be noted that the present invention forms a Schiff base compound coating layer on the surface of nano-titanium dioxide particles by sequentially using dopamine and dialdehyde in situ polymerization. By coating the filler surface with a hydrophobic and heat-resistant layer, the uniform dispersion of titanium dioxide particles in silicone rubber matrix is ​​achieved, and a three-dimensional cross-linked network structure of Schiff base compounds is constructed in silicone rubber matrix through the dispersion of filler. Schiff base compounds have good thermal shock resistance and stability, and the three-dimensional structure formed on the filler surface can significantly improve the heat aging resistance of silicone rubber.

[0045] In a preferred embodiment, the weight ratio of the dopamine, the dialdehyde, and the nano-titanium dioxide particles is (3~5.5):(0.5~0.9):(0.6~1.5).

[0046] In one embodiment, the dialdehyde is selected from any two of glyoxal, p-hydroxybenzaldehyde, furanaldehyde, cinnamaldehyde, vanillin, o-vanillin, and salicylaldehyde.

[0047] It should be noted that by using specific types of aldehydes to react with dopamine to generate Schiff base compounds, the aldehydes used in this invention are all low in toxicity and have high antibacterial properties. On the one hand, they can synergistically enhance the antibacterial effect; on the other hand, different aldehydes contain different active groups and structures, which can strengthen the cross-linking stability.

[0048] In a preferred embodiment, the mass ratio of the two different aldehydes in the dual aldehydes is (1~2):(12~15).

[0049] In one embodiment, the structural modifier is selected from at least one of 2-(4-pyridylethyl)triethoxysilane, 3-pyridyltrimethoxysilane, 1-(trimethyl)-1H-imidazolium, 3-(1-imidazolium)propyltriethoxysilane, and N-imidazoliumpropyltrimethoxysilane.

[0050] It should be noted that, in this invention, by adding siloxanes modified with imidazole and / or pyridyl groups as structural modifiers, on the one hand, the strong coordination ability of these modifiers fixes heavy metal ions within the silicone rubber, thereby reducing the cytotoxicity of the silicone rubber product; on the other hand, the imidazole or pyridyl groups in the structural modifiers can chemically crosslink or physically entangle with the active groups on the surface of the antibacterial composite particles and the active groups in the Schiff base structure on the surface of the nano-titanium dioxide particles, so that the filler molecules maintain a reasonable spacing and uniform dispersion within the silicone rubber matrix, while also improving the elongation of the liquid silicone rubber and giving it a certain degree of flexibility.

[0051] In one embodiment, the inhibitor is an alkynol compound.

[0052] In one embodiment, the catalyst is a cassiterite catalyst.

[0053] In a preferred embodiment, the vinyl polysiloxane comprises terminal vinyl silicone oil and side-chain vinyl silicone oil, wherein the viscosity of the terminal vinyl silicone oil is 50,000 cs to 60,000 cs; the viscosity of the side-chain vinyl silicone oil is 1,000 cs to 10,000 cs, and the vinyl content is 0.5 wt% to 1 wt%.

[0054] In a preferred embodiment, the vinyl polysiloxane comprises terminal vinyl silicone oil and side-chain vinyl silicone oil in a weight ratio of (2~3.5):(0.8~1.3).

[0055] In a preferred embodiment, the end groups and side chain groups of the hydrogenated polysiloxane contain silane groups, wherein the hydrogen content is 0.2wt%-0.8wt%.

[0056] In a preferred embodiment, the vinyl content in the MQ silicone resin is 0.1% to 4%, the M / Q value is 1 to 1.5, and the number average molecular weight is 2000 g / mol to 5000 g / mol.

[0057] It should be noted that the vinyl polysiloxane used in this invention employs a combination of terminal vinyl silicone oil and side-chain vinyl silicone oil, which allows for the control of the crosslinking density of the resulting liquid silicone rubber at a reasonable level, enabling the liquid silicone rubber to possess good flexibility and a pleasant tactile feel while maintaining a certain strength. Furthermore, the addition of a specific MQ silicone resin can significantly improve the compression set properties of the silicone rubber.

[0058] This invention also provides a method for preparing liquid silicone rubber, comprising the following steps:

[0059] S1. Mix 50 to 100 parts of vinyl polysiloxane with all the nano titanium dioxide particles, composite antibacterial particles and structural modifier, knead, knead at 120°C to 20°C for 10 to 20 minutes, discharge and let stand for 5 to 10 hours, then knead at room temperature for 1 to 3 hours to obtain the base rubber.

[0060] S2. Add 15 to 60 parts of vinyl polysiloxane to half of the base adhesive prepared in step S1 and disperse evenly. Then add all of the MQ silicone resin and catalyst and mix evenly. Degas under vacuum to obtain component A. Add the remaining vinyl polysiloxane to the remaining base adhesive prepared in step S1 and disperse evenly. Then add all of the hydrogenated polysiloxane and mix evenly. Add all of the inhibitor and mix. Degas under vacuum to obtain component B.

[0061] S3. Mix component A and component B, place them in a mold and vulcanize to obtain liquid silicone rubber.

[0062] In one embodiment, in step S3, the vulcanization temperature is 130℃~180℃, the vulcanization pressure is 3MPa~5MPa, and the vulcanization time is 20min~30min.

[0063] The present invention will be further illustrated below through specific embodiments:

[0064] This invention does not impose specific restrictions on the source of raw materials. The sources of raw materials in the various embodiments of this invention are as follows:

[0065] Vinyl-terminated silicone oil, purchased from Jiangxi Lanxing Xinghuo Organosilicon Co., Ltd., product number 621V60000, viscosity 60000cs;

[0066] Side-chain vinyl silicone oil, purchased from Shin-Etsu Chemical, product number KF-99T, viscosity approximately 1,000 cs~2,000 cs, vinyl content 0.5wt%~0.6wt%.

[0067] Hydrogenated polysiloxane, purchased from Jiangxi Lanxing Xinghuo Organosilicon Co., Ltd., item number 626V9H4, contains silane groups in both the end groups and side chain groups, with an average hydrogen content of 0.4wt%.

[0068] MQ silicone resin, purchased from Wynca Group, product number WX-MQ101, vinyl content: approximately 1wt%~1.5wt%, M / Q value: 1~1.2; number average molecular weight: 3500~5000.

[0069] Black phosphorus nanosheets, purchased from XFNANO, catalog number 101927 - Black phosphorus nanosheet dispersion (approximately 4 wt% concentration, solvent: water).

[0070] The nano-titanium dioxide particles were purchased from Shanghai Maclean Biochemical Technology Co., Ltd., model number T818931, with an average particle size of approximately 40 nm.

[0071] Platinum catalyst, purchased from Ziyue, model PL-56, platinum concentration approximately 5000ppm.

[0072] Example 1

[0073] The liquid silicone rubber in Example 1 comprises the following raw materials in parts by weight:

[0074] Vinyl polysiloxane: 160 parts by weight; Nano titanium dioxide particles: 20 parts by weight; Hydrogenated polysiloxane: 12 parts by weight; MQ silicone resin: 33 parts by weight; Composite antibacterial particles: 10 parts by weight; Structural modifier: 3 parts by weight; Catalyst: 1.2 parts by weight; Inhibitor: 0.6 parts by weight;

[0075] In Example 1, the vinyl polysiloxane comprises 115 parts by weight of terminal vinyl silicone oil and 45 parts by weight of side-chain vinyl silicone oil; the structural modifier is N-imidazolium propyltrimethoxysilane; the inhibitor is 1-ethynyl-1-cyclohexanol; and the catalyst is platinum catalyst PL-56.

[0076] The preparation process of the composite antibacterial particles in Example 1 includes the following steps:

[0077] The pH of the black phosphorus nanosheet dispersion was adjusted to 5-6, and a 5 wt% silver nitrate solution was added dropwise while stirring. After the addition was complete, the mixture was stirred evenly, and an excess sodium citrate solution was added. The mixture was reacted at 60°C for 1 hour, the precipitate was collected, washed, and vacuum dried to obtain the antibacterial particle intermediate.

[0078] Hexadecyl acrylate was mixed with the antibacterial particle intermediate and stirred at 80°C for 2 hours. The precipitate was collected to obtain composite antibacterial particles.

[0079] Among them, the black phosphorus nanosheets in the black phosphorus nanosheet dispersion and Ag in the silver nitrate solution + The molar ratio is approximately 1:4.5; the weight ratio of black phosphorus nanosheets to hexadecyl acrylate is approximately 1:4.

[0080] The preparation method of liquid silicone rubber in Example 1 includes the following steps:

[0081] S1. Under normal temperature and nitrogen atmosphere protection, 55 parts by weight of terminal vinyl silicone oil, 25 parts by weight of side chain vinyl silicone oil, 20 parts by weight of nano titanium dioxide particles, 10 parts by weight of composite antibacterial particles, and 3 parts by weight of structural modifier are mixed, kneaded, and kneaded at 160°C for 20 minutes. The mixture is discharged, allowed to stand for 5 hours, and kneaded at room temperature for 1 hour to obtain a base rubber with a total weight of 113 parts by weight.

[0082] S2. Add 30 parts by weight of terminal vinyl silicone oil and 10 parts by weight of side-chain vinyl silicone oil to 56.5 parts by weight of the base adhesive obtained in step S1, then add 33 parts by weight of MQ silicone resin and 1.2 parts by weight of catalyst, mix evenly, and degas under vacuum to obtain component A; add 30 parts by weight of terminal vinyl silicone oil and 10 parts by weight of side-chain vinyl silicone oil to 56.5 parts by weight of the base adhesive obtained in step S1, then add 12 parts by weight of hydrogenated polysiloxane and 0.6 parts by weight of inhibitor, mix evenly, and degas under vacuum to obtain component B;

[0083] S3. Mix component A and component B, place them in a mold for vulcanization, control the vulcanization temperature at 140°C, the vulcanization pressure at 3MPa, and the vulcanization time at about 20 minutes to obtain liquid silicone rubber.

[0084] Example 2

[0085] The liquid silicone rubber in Example 2 comprises the following parts by weight of raw materials:

[0086] Vinyl polysiloxane: 200 parts by weight; Nano titanium dioxide particles: 15 parts by weight; Hydrogenated polysiloxane: 5 parts by weight; MQ silicone resin: 50 parts by weight; Composite antibacterial particles: 8 parts by weight; Structural modifier: 2 parts by weight; Catalyst: 2 parts by weight; Inhibitor: 0.6 parts by weight;

[0087] In Example 2, the vinyl polysiloxane comprises 145 parts by weight of terminal vinyl silicone oil and 55 parts by weight of side-chain vinyl silicone oil; the structural modifier is 3-pyridyltrimethoxysilane; the inhibitor is 1-ethynyl-1-cyclohexanol; and the catalyst is platinum catalyst PL-56.

[0088] The preparation process of the composite antibacterial particles in Example 2 is the same as that in Example 1.

[0089] The preparation method of liquid silicone rubber in Example 2 includes the following steps:

[0090] S1. Under normal temperature and nitrogen atmosphere protection, 90 parts by weight of terminal vinyl silicone oil, 30 parts by weight of side chain vinyl silicone oil, 15 parts by weight of nano titanium dioxide particles, 8 parts by weight of composite antibacterial particles, and 2 parts by weight of structural modifier are mixed, kneaded, and kneaded at 160°C for 20 minutes. The mixture is discharged, allowed to stand for 5 hours, and kneaded at room temperature for 1 hour to obtain a base rubber with a total weight of 145 parts by weight.

[0091] S2. Add 30 parts by weight of terminal vinyl silicone oil and 10 parts by weight of side-chain vinyl silicone oil to 72.5 parts by weight of the base adhesive obtained in step S1, then add 50 parts by weight of MQ silicone resin and 2 parts by weight of catalyst, mix evenly, and degas under vacuum to obtain component A; add 25 parts by weight of terminal vinyl silicone oil and 15 parts by weight of side-chain vinyl silicone oil to 72.5 parts by weight of the base adhesive obtained in step S1, then add 5 parts by weight of hydrogenated polysiloxane and 0.6 parts by weight of inhibitor, mix evenly, and degas under vacuum to obtain component B;

[0092] S3. Mix component A and component B, place them in a mold for vulcanization, control the vulcanization temperature at 180°C, the vulcanization pressure at 3MPa, and the vulcanization time at about 20 minutes to obtain liquid silicone rubber.

[0093] Example 3

[0094] The liquid silicone rubber in Example 3 comprises the following raw materials in parts by weight:

[0095] Vinyl polysiloxane: 150 parts by weight; Nano titanium dioxide particles: 25 parts by weight; Hydrogenated polysiloxane: 15 parts by weight; MQ silicone resin: 30 parts by weight; Composite antibacterial particles: 18 parts by weight; Structural modifier: 5 parts by weight; Catalyst: 2 parts by weight; Inhibitor: 1 part by weight;

[0096] In Example 3, the vinyl polysiloxane comprises 110 parts by weight of terminal vinyl silicone oil and 40 parts by weight of side-chain vinyl silicone oil; the structural modifier is 3-pyridyltrimethoxysilane; the inhibitor is 1-ethynyl-1-cyclohexanol; and the catalyst is platinum catalyst PL-56.

[0097] The preparation process of the composite antibacterial particles in Example 3 is the same as that in Example 1.

[0098] The preparation method of liquid silicone rubber in Example 3 includes the following steps:

[0099] S1. Under normal temperature and nitrogen atmosphere protection, 60 parts by weight of terminal vinyl silicone oil, 25 parts by weight of side chain vinyl silicone oil, 25 parts by weight of nano titanium dioxide particles, 18 parts by weight of composite antibacterial particles, and 5 parts by weight of structural modifier are mixed, kneaded, and kneaded at 160°C for 20 minutes. The mixture is discharged, allowed to stand for 5 hours, and kneaded at room temperature for 1 hour to obtain a base rubber with a total weight of 133 parts by weight.

[0100] S2. Add 30 parts by weight of terminal vinyl silicone oil and 10 parts by weight of side-chain vinyl silicone oil to 66.5 parts by weight of the base adhesive obtained in step S1, then add 30 parts by weight of MQ silicone resin and 2 parts by weight of catalyst, mix evenly, and degas under vacuum to obtain component A; add 20 parts by weight of terminal vinyl silicone oil and 5 parts by weight of side-chain vinyl silicone oil to 66.5 parts by weight of the base adhesive obtained in step S1, then add 15 parts by weight of hydrogenated polysiloxane and 1 part by weight of inhibitor, mix evenly, and degas under vacuum to obtain component B;

[0101] S3. Mix component A and component B, place them in a mold for vulcanization, control the vulcanization temperature at 160°C, the vulcanization pressure at 5MPa, and the vulcanization time at about 20 minutes to obtain liquid silicone rubber.

[0102] Example 4

[0103] Example 4 is based on Example 1, except that the nano-titanium dioxide particles in Example 4 are modified nano-titanium dioxide particles, and the preparation method includes the following steps:

[0104] Nano-titanium dioxide particles were dispersed in a dopamine solution with a concentration of approximately 5 mg / mL. Sodium hydroxide was added and the pH was adjusted to approximately 9-11. The solution temperature was maintained at 35°C, and the reaction was carried out for 5 hours to obtain a titanium dioxide intermediate. The dialdehyde and the titanium dioxide intermediate were dispersed in anhydrous ethanol, and the temperature was maintained at 60°C. The reaction was carried out for 3 hours with reflux condensation during the reaction. After the reaction was completed, the solid precipitate was collected and dried under vacuum to obtain modified nano-titanium dioxide particles.

[0105] The weight ratio of dopamine, dialdehyde, and nano-titanium dioxide particles is approximately 3:0.8:8; the dialdehyde includes vanillin and glyoxal in a weight ratio of 2:0.5.

[0106] The preparation method of the liquid silicone rubber in Example 4 is the same as that in Example 1.

[0107] Example 5

[0108] Example 5 is based on Example 2, except that the nano-titanium dioxide particles in Example 5 are modified nano-titanium dioxide particles, and the preparation method of the modified nano-titanium dioxide particles is the same as that in Example 4.

[0109] The preparation method of the liquid silicone rubber in Example 5 is the same as that in Example 2.

[0110] Example 6

[0111] Example 6 is based on Example 3, except that the nano-titanium dioxide particles in Example 6 are modified nano-titanium dioxide particles, and the preparation method of the modified nano-titanium dioxide particles is the same as that in Example 4.

[0112] The preparation method of the liquid silicone rubber in Example 6 is the same as that in Example 3.

[0113] Example 7

[0114] Example 7 is based on Example 4, except that the structural modifier in Example 7 is replaced with an equal amount of 3-pyridyltrimethoxysilane.

[0115] Example 8

[0116] Example 8 is based on Example 4, except that in the preparation process of the modified nano-titanium dioxide particles in Example 8, a single type of glyoxal is used instead of two aldehydes.

[0117] Comparative Example 1

[0118] Comparative Example 1 is based on Example 1, except that black phosphorus nanosheets are not used in the preparation of the composite antibacterial particles. The preparation method of the composite antibacterial particles in Comparative Example 1 includes the following steps:

[0119] The pH of the silver nitrate solution was adjusted to approximately 5-6, and an excess of sodium citrate solution was added. The mixture was kept at 60°C for 1 hour, and the precipitate was collected, washed, and dried to obtain an antibacterial particle intermediate. Cetyl acrylate was mixed with the antibacterial particle intermediate, and the mixture was stirred at 80°C for 2 hours. The precipitate was collected to obtain composite antibacterial particles.

[0120] Comparative Example 2

[0121] Comparative Example 2 is based on Example 1, except that the structural modifier is replaced by an equal amount of propyltrimethoxysilane instead of N-imidazolium propyltrimethoxysilane.

[0122] Comparative Example 3

[0123] Comparative Example 3 is based on Example 4, except that the structural modifier is replaced by an equal amount of propyltrimethoxysilane instead of N-imidazolium propyltrimethoxysilane.

[0124] Comparative Example 4

[0125] Comparative Example 4 is based on Example 1, except that the amount of MQ silicone resin is changed from 33 parts by weight to 10 parts by weight.

[0126] Performance testing

[0127] 1. The tensile strength (MPa) and elongation at break (%) of the 2 mm thick liquid silicone rubber sheets of Examples 1-8 and Comparative Examples 1-4 were determined according to standard GBT528-2008.

[0128] 2. The Shore A hardness of the 2 mm thick liquid silicone rubber sheets of Examples 1-8 and Comparative Examples 1-4 was determined according to standard GB / T 531.1-2008.

[0129] 3. Referring to standard GB / T 528-2009, the tensile strength and elongation at break changes of 2mm thick liquid silicone rubber sheets from Examples 1-8 and Comparative Examples 1-4 after UV aging tests were determined. The UV aging test conditions included: a 20W UV lamp, a wavelength of 253.78nm, and a UV irradiation intensity controlled at approximately 120 (VM / cm²). 2 The changes in tensile strength and elongation at break were measured after aging times of 200 h and 400 h, respectively.

[0130] 4. The high-temperature heating rapid aging method was used to determine the change rate of tensile strength and the change rate of elongation at break of the liquid silicone rubber of Examples 1-8 and Comparative Examples 1-4 after heating at 150°C for 48h, 96h and 144h.

[0131] 5. The antibacterial activity R values ​​of the liquid silicone rubbers in Examples 1-8 and Comparative Examples 1-4 against Staphylococcus aureus ATCC6538 and Escherichia coli ATCC8739 were determined according to standard GB / T31402-2015. The calculation of the antibacterial activity R value is: R=(Ut-Uo)-(At-Uo)=Ut-At, where Uo is the logarithmic mean of the number of viable bacteria after inoculation at time "0" in the control sample, in cfu / cm³. 2 Ut represents the average viable bacterial count of the control sample after 24 hours of inoculation, expressed in cfu / cm³. 2 At—The average number of viable bacteria on the antibacterial sample after 24 hours of incubation, expressed in cfu / cm³. 2 .

[0132] The measurement results are shown in Tables 1 and 2.

[0133] Table 1

[0134]

[0135] Table 2

[0136]

[0137] Analysis of the data in Tables 1 and 2 shows that the use of specific structural modifiers combined with two specific functional fillers in this invention effectively reduces the damage to the properties of liquid silicone rubber caused by ultraviolet radiation and high temperatures, and effectively improves the heat aging resistance and UV aging resistance of silicone rubber. After heat aging and UV aging tests, the mechanical properties of the liquid silicone rubber of this invention are still highly retained. Furthermore, the liquid silicone rubber of this invention also has high antibacterial properties and good human biocompatibility, making it economically valuable for application in high-end civilian silicone rubber products or medical silicone rubber products.

[0138] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A liquid silicone rubber, characterized in that, The liquid silicone rubber comprises the following raw materials in parts by weight: Vinyl polysiloxane: 150 parts to 200 parts; Nano titanium dioxide particles: 15 to 25 parts; Hydrogenated polysiloxane: 5 to 15 parts; MQ silicone resin: 30-50 parts; Composite antibacterial particles: 8 to 18 parts; Structural modifier: 2 to 5 parts; Catalyst: 0.6 to 2.4 parts; Inhibitor: 0.1 to 1 part; The composite antibacterial particles are prepared from black phosphorus nanosheets, silver nitrate and long-chain alkyl acrylates; the structural modifier is an imidazole and / or pyridinyl modified siloxane. The preparation method of the composite antibacterial particles includes the following steps: The pH of the black phosphorus nanosheet dispersion was adjusted to 5-6, and silver nitrate solution was added dropwise while stirring. Then sodium citrate solution was added, and the mixture was reacted at 60℃-65℃ for 1-2 hours. The precipitate was collected, washed, and vacuum dried to obtain the antibacterial particle intermediate. The long-chain alkyl acrylate was mixed with the antibacterial particle intermediate and reacted at 70℃-80℃ for 2-3 hours. The precipitate was collected to obtain the composite antibacterial particles. In the composite antibacterial particles, the black phosphorus nanosheets and the Ag in the silver nitrate solution + The molar ratio is 1:(4~8); the black phosphorus nanosheet dispersion contains 3wt%~6wt% black phosphorus nanosheets; the weight ratio of the black phosphorus nanosheets to the long-chain alkyl acrylate is 1:(3~10).

2. The liquid silicone rubber as described in claim 1, characterized in that, The nano-titanium dioxide particles are modified nano-titanium dioxide particles; The modified nano-titanium dioxide particles are nano-silica particles coated with Schiff base compounds.

3. The liquid silicone rubber as described in claim 2, characterized in that, The preparation method of the modified nano-titanium dioxide particles includes the following steps: Nano-titanium dioxide particles were dispersed in a dopamine solution with a concentration of 2 mg / mL to 10 mg / mL. Sodium hydroxide was added and the pH was adjusted to 9 to 11. The solution temperature was maintained at 30℃ to 35℃, and the reaction was carried out for 5 to 8 hours to obtain a titanium dioxide intermediate. The dialdehyde and the titanium dioxide intermediate were dispersed in anhydrous ethanol. The temperature was maintained at 50℃ to 60℃, and the reaction was carried out for 3 hours. The mixture was refluxed while reacting. After the reaction was completed, the solid precipitate was collected and dried under vacuum to obtain the modified nano-titanium dioxide particles.

4. The liquid silicone rubber as described in claim 3, characterized in that, The weight ratio of the dopamine, the dialdehyde, and the nano-titanium dioxide particles is (3~5.5):(0.5~0.9):(0.6~1.5).

5. The liquid silicone rubber as described in claim 3, characterized in that, The dialdehyde is selected from any two of glyoxal, p-hydroxybenzaldehyde, furanaldehyde, cinnamaldehyde, vanillin, o-vanillin, and salicylaldehyde.

6. The liquid silicone rubber as described in claim 1, characterized in that, The structural modifier is selected from at least one of 2-(4-pyridylethyl)triethoxysilane, 3-pyridyltrimethoxysilane, 1-(trimethyl)-1H-imidazolium, 3-(1-imidazolium)propyltriethoxysilane, and N-imidazoliumpropyltrimethoxysilane; And / or, the inhibitor is an alkynol compound; And / or, the catalyst is a cassiterite catalyst.

7. A method for preparing liquid silicone rubber according to any one of claims 1 to 6, characterized in that, The preparation method of the liquid silicone rubber includes the following steps: S1. Mix 50 to 100 parts of vinyl polysiloxane with all the nano titanium dioxide particles, composite antibacterial particles and structural modifier, knead, knead at 120°C to 20°C for 10 to 20 minutes, discharge and let stand for 5 to 10 hours, then knead at room temperature for 1 to 3 hours to obtain the base rubber. S2. Add 15 to 60 parts of vinyl polysiloxane to half of the base adhesive prepared in step S1 and disperse evenly. Then add all of the MQ silicone resin and catalyst and mix evenly. Degas under vacuum to obtain component A. Add the remaining vinyl polysiloxane to the remaining base adhesive prepared in step S1 and disperse evenly. Then add all of the hydrogenated polysiloxane and mix evenly. Add all of the inhibitor and mix. Degas under vacuum to obtain component B. S3. Mix component A and component B, place them in a mold and vulcanize to obtain liquid silicone rubber.

8. The method for preparing liquid silicone rubber as described in claim 7, characterized in that, In step S3, the vulcanization temperature is 130℃~180℃, the vulcanization pressure is 3MPa~5MPa, and the vulcanization time is 20min~30min.

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