Preparation method of high-strength and high-antibacterial modified silicone rubber material

Abstract

The invention discloses a preparation method of a high-strength and high-antibacterial modified silicone rubber material, graphene oxide powder containing a silane coupling agent is subjected to water vapor treatment to improve the degree of freedom of graphene oxide sheets, and in the process of compounding with raw silicone rubber, the degree of freedom of the graphene oxide sheets is improved by virtue of the combination effect of silica gel molecules and the graphene oxide sheets, so that the high-strength and high-antibacterial modified silicone rubber material is obtained. Graphene oxide sheets are gradually dissociated into sheet structures, and a uniform reduced graphene oxide / silica gel composite system is formed under the action of a reducing agent. According to the system, stress can be effectively transmitted to graphene sheets, the tensile resistance and tear resistance of silica gel are remarkably improved, and meanwhile, due to the existence of the reduced graphene oxide sheets, the overall antibacterial property of the material is remarkably improved.

Description

Technical Field

[0001] The invention relates to the field of silicone rubber materials, in particular to a method for preparing a high-strength and highly antibacterial modified silicone rubber material. Background Art

[0002] Silicone rubber is a polymer elastic material with silicon-oxygen bonds as the main chain and organic groups attached to silicon atoms. It has excellent high temperature resistance, low temperature resistance, weather resistance, electrical insulation and good biocompatibility. Due to these characteristics, silicone is widely used in medical, electronic, automotive, construction and daily necessities. Silicone materials can be divided into various types such as heat vulcanization type, room temperature vulcanization type, liquid type, etc. according to their cross-linking density, molecular structure and performance, in order to meet the needs of various application scenarios.

[0003] Although silicone rubber has outstanding advantages, it still lacks in mechanical properties, especially tensile and tear resistance, which limits its use in some applications that require high-strength materials. In addition, the antibacterial properties of silicone are not enough to meet the needs of certain specific occasions, such as medical supplies and pet supplies, which have higher requirements for the antibacterial properties of materials. In order to meet these needs, researchers have explored a variety of modification methods, including filling reinforcement, blending modification, etc. For example, the hardness and heat resistance of silicone can be improved by adding inorganic fillers such as calcium carbonate and zinc oxide, but these methods often sacrifice the flexibility and elasticity of the material. In addition, through blending modification, such as mixing with other polymer materials such as polyester and polyether, the mechanical properties of silicone can be improved to a certain extent, but these methods are often costly and complex processes.

[0004] In recent years, graphene has received extensive attention due to its high strength, high electrical and thermal conductivity, and excellent processing performance, and the development of graphene composite silicone products has also developed rapidly. However, during the blending and modification process, the dispersion problem of graphene powder has gradually become prominent. On the one hand, it is difficult to effectively disperse it through external forces due to the serious stacking of graphene itself. On the other hand, the bonding force between graphene and silicone is insufficient, and it is also difficult to improve the dispersion effect of graphene sheets from the perspective of chemical action. Therefore, the preparation of high-performance graphene-modified silicone materials is still a major problem, which restricts the development of related industries. Summary of the invention

[0005] In view of the problems raised in the background technology, the present invention provides a method for preparing a high-strength and highly antibacterial modified silicone rubber material, which significantly improves the mechanical properties and antibacterial properties of silicone rubber by introducing a unique graphene oxide additive. The specific preparation steps include:

[0006] (1) adding a silane coupling agent to a graphene oxide slurry, mixing the mixture evenly, and spray drying the mixture to obtain a modified graphene oxide powder, wherein the mass ratio of the silane coupling agent to the graphene oxide is 0.5-3:10, and the concentration of the graphene oxide slurry is 3-15 mg / g; (2) fumigating the modified graphene oxide powder in a water vapor atmosphere to obtain water vapor-treated modified graphene oxide powder; (3) mixing 0.5-10 parts of the modified graphene oxide powder treated with water vapor with 100 parts of silicone rubber raw rubber, 10-30 parts of inorganic filler, 10 parts of sodium ascorbate, and 1-2 parts of antioxidant to obtain a modified raw rubber; (4) The modified raw rubber is mixed with 0.5 to 2 parts of sulfur and 2 to 3 parts of an accelerator and then hot-pressed and vulcanized to obtain a high-strength and highly antibacterial modified silicone rubber material.

[0007] Furthermore, the solvent of the graphene oxide slurry in step (1) is a mixture of one or more of water, DMF, DMSO, and NMP, and the diameter of the graphene oxide flakes is 2 to 50 μm. The silane coupling agent contains one or more of an amino group, an epoxy group, and an isocyanate group. By mixing graphene oxide with the silane coupling agent, the bonding force between graphene oxide and silica gel molecules is enhanced, laying a foundation for dispersing graphene oxide flakes in subsequent processing.

[0008] Furthermore, the water vapor fumigation time in step (2) is 5 to 30 minutes, and the fumigation temperature is 90 to 120° C. In the water vapor atmosphere, the oxygen-containing functional groups on the surface of the graphene oxide sheets adsorb a large number of water molecules, which reduces the binding force between the graphene oxide sheets, improves the freedom of movement of the graphene oxide sheets, and makes it easier to dissociate and stretch into a sheet structure under the action of external force, so that the mechanical properties and antibacterial properties of the reduced graphene oxide are better realized.

[0009] Furthermore, the antioxidant in step (3) is a phosphite antioxidant. The mixing temperature is 45 to 60°C, and the mixing time is 10 to 30 minutes. The inorganic filler is a mixture of one or more of alumina, titanium dioxide, quartz powder, kaolin, talc, and calcium carbonate. Selecting a reasonable mixing time and temperature helps the graphene oxide paper group to dissociate under the action of external force and restore the flaky structure. The addition of sodium ascorbate causes the graphene oxide to undergo a reduction reaction during the mixing process, the oxygen-containing groups are removed and gas is generated, and some micropores are generated in the silica gel. At the same time, the structure of the graphene oxide is restored and the mechanical properties are improved. Reducing the graphene oxide retains some unreacted groups, which helps to achieve the antibacterial properties of the composite silica gel.

[0010] Furthermore, the accelerator in step (4) is a sulfonamide accelerator.

[0011] Furthermore, the hot pressing vulcanization temperature in step (5) is 120-200°C.

[0012] Beneficial effects of the present invention: (1) Achieve molecular-level uniform dispersion of graphene oxide sheets: After spray drying, the graphene oxide sheets are wrinkled and overlapped to form paper-like graphene oxide powders. Due to their own stacking effect, graphene oxide sheets are difficult to unfold simply by mechanical action to restore their sheet structure, especially under heating or reducing atmospheres, and it is more difficult to achieve unfolding with the removal of groups. In the prior art, there are reports on using the characteristics of polymer precursors to gradually dissociate graphene oxide powders into sheets before / during polymerization to achieve uniform compounding (such as CN107325268B). However, restoring the morphology of graphene oxide powders to sheets in non-in-situ polymerization systems is still a major problem. For the preparation of silica gel, whether it is mixing in the solid state or mixing with high-viscosity liquid silica gel, it is not conducive to the dissociation of the graphene oxide paper structure. The present invention discovers for the first time that graphene oxide powder can absorb moisture under water vapor, introducing a free movement environment between highly wrinkled graphene oxide sheets, so that under solid-state mixing, it can also unfold into sheets along with silica gel molecules by relying on the action of silane coupling agent and tightly combine with silica gel molecules to form a high-strength and highly antibacterial composite material.

[0013] (2) Unique microporous structure: The small amount of water vapor introduced evaporates during the subsequent mixing, forming some micropores in the system. In addition, the added sodium ascorbate undergoes a reduction reaction with graphene oxide, and the oxygen-containing functional groups on the surface of graphene oxide are removed in the form of gas, further forming a microporous structure and effectively reducing the density of the silica gel matrix. At the same time, the reduced graphene oxide has better mechanical properties, which improves the tensile and tear resistance of the composite silica gel.

[0014] (3) Easy to prepare on an industrial scale: On the basis of conventional silica gel production, a small amount of graphene oxide powder is added, and only water vapor is used to treat the graphene oxide. The whole process is environmentally friendly, and the equipment and raw materials are simple and easy to obtain, which is particularly suitable for large-scale preparation applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the morphology of the modified graphene oxide powder prepared in Example 1 of the present invention.

[0016] Figure 2 This is the cross-sectional microscopic morphology of the modified silicone rubber material prepared in Example 1 of the present invention.

[0017] Figure 3 This is the cross-sectional microscopic morphology of the modified silicone rubber material prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0018] The embodiments of the present invention are further described below with reference to a plurality of embodiments.

[0019] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0020] The raw materials used in the present invention, unless otherwise specified, are conventional commercially available products; the methods used in the present invention, unless otherwise specified, are conventional methods in the art.

[0021] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms of "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings. The terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first" and "second" can explicitly or implicitly include one or more of the features.

[0022] In the description of the present invention, “plurality” means two or more than two, unless clearly defined otherwise.

[0023] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0024] Example 1 (1) Adding KH550 silane coupling agent to graphene oxide aqueous dispersion, mixing evenly and spray drying to obtain modified graphene oxide powder, wherein the mass ratio of silane coupling agent to graphene oxide is 1:10, the concentration of graphene oxide slurry is 3 mg / g, and the flake diameter of graphene oxide is 40-50 μm; (2) placing the modified graphene oxide powder in a water vapor atmosphere for fumigation for 10 minutes at a fumigation temperature of 90° C. to obtain water vapor-treated modified graphene oxide powder; (3) mixing 1 part of the modified graphene oxide powder treated with water vapor with 100 parts of silicone rubber raw rubber, 10 parts of aluminum oxide, 10 parts of sodium ascorbate, and 1 part of phosphite at 45° C. for 10 minutes to obtain a modified raw rubber; (4) The modified raw rubber is mixed with 1 part of sulfur and 2 parts of CZ accelerator and then hot-pressed and vulcanized at 200°C to obtain a high-strength and highly antibacterial modified silicone rubber material.

[0025] The morphology of the modified graphene oxide powder prepared in step (1) is as follows: Figure 1 As shown, it is a paper ball-like morphology, composed of highly wrinkled graphene oxide sheets. The modified silicone rubber material obtained in step (4) is a black block, and its microscopic morphology is as follows Figure 2 As shown, it can be found that the interior is uniform and free of foreign matter, and there are no obvious particles or wrinkles. Its tensile strength is 7.36 MPa, its elongation at break is 217%, and its antibacterial properties against Staphylococcus aureus, Escherichia coli and Candida albicans are 98%, 96% and 92% respectively.

[0026] Example 2 (1) Adding KH550 silane coupling agent to graphene oxide aqueous dispersion, mixing evenly and spray drying to obtain modified graphene oxide powder, wherein the mass ratio of silane coupling agent to graphene oxide is 0.5:10, the concentration of graphene oxide slurry is 10 mg / g, and the flake diameter of graphene oxide is 2-10 μm; (2) placing the modified graphene oxide powder in a water vapor atmosphere for fumigation for 5 minutes at a fumigation temperature of 90° C. to obtain water vapor-treated modified graphene oxide powder; (3) mixing 5 parts of the modified graphene oxide powder treated with water vapor with 100 parts of silicone rubber raw rubber, 10 parts of aluminum oxide, 10 parts of sodium ascorbate, and 2 parts of phosphite at 45° C. for 10 minutes to obtain a modified raw rubber; (4) The modified raw rubber was mixed with 1.5 parts of sulfur and 2.5 parts of CZ accelerator and then hot-pressed and vulcanized at 200°C to obtain a high-strength and highly antibacterial modified silicone rubber material.

[0027] The obtained modified silicone rubber material has a tensile strength of 8.29 MPa and an elongation at break of 196%. Its antibacterial properties against Staphylococcus aureus, Escherichia coli and Candida albicans are 99%, 97% and 94%, respectively.

[0028] Example 3 (1) Adding KH560 silane coupling agent to graphene oxide DMF dispersion, mixing evenly and spray drying to obtain modified graphene oxide powder, wherein the mass ratio of silane coupling agent to graphene oxide is 3:10, the concentration of graphene oxide slurry is 15 mg / g, and the flake diameter of graphene oxide is 2-10 μm; (2) placing the modified graphene oxide powder in a water vapor atmosphere for fumigation for 30 minutes at a fumigation temperature of 120° C. to obtain water vapor-treated modified graphene oxide powder; (3) mixing 10 parts of the modified graphene oxide powder treated with water vapor with 100 parts of silicone rubber raw rubber, 30 parts of aluminum oxide, 10 parts of sodium ascorbate, and 2 parts of phosphite at 60° C. for 30 minutes to obtain a modified raw rubber; (4) The modified raw rubber is mixed with 2 parts of sulfur and 3 parts of NOBS accelerator and then hot-pressed and vulcanized at 150°C to obtain a high-strength and highly antibacterial modified silicone rubber material.

[0029] The obtained modified silicone rubber material has a tensile strength of 8.66 MPa, an elongation at break of 172%, and antibacterial properties against Staphylococcus aureus, Escherichia coli, and Candida albicans of 99%, 96%, and 93%, respectively.

[0030] Example 4 (1) Adding KH560 silane coupling agent to a water / DMF mixed dispersion of graphene oxide, mixing evenly and spray drying to obtain modified graphene oxide powder, wherein the mass ratio of silane coupling agent to graphene oxide is 1:10, the concentration of graphene oxide slurry is 8 mg / g, and the flake diameter of graphene oxide is 20-30 μm; (2) fumigating the modified graphene oxide powder in a water vapor atmosphere for 20 minutes at a fumigation temperature of 100° C. to obtain water vapor-treated modified graphene oxide powder; (3) mixing 0.5 parts of the modified graphene oxide powder treated with water vapor with 100 parts of silicone rubber raw rubber, 20 parts of aluminum oxide, 10 parts of sodium ascorbate, and 2 parts of phosphite at 50° C. for 20 minutes to obtain a modified raw rubber; (4) The modified raw rubber is mixed with 2 parts of sulfur and 2 parts of NOBS accelerator and then hot-pressed and vulcanized at 120°C to obtain a high-strength and highly antibacterial modified silicone rubber material.

[0031] The obtained modified silicone rubber material has a tensile strength of 7.19 MPa, an elongation at break of 235%, and antibacterial properties against Staphylococcus aureus, Escherichia coli, and Candida albicans of 98%, 95%, and 91%, respectively.

[0032] Comparative Example 1 (1) Adding KH550 silane coupling agent to graphene oxide aqueous dispersion, mixing evenly and spray drying to obtain modified graphene oxide powder, wherein the mass ratio of silane coupling agent to graphene oxide is 1:10, the concentration of graphene oxide slurry is 3 mg / g, and the flake diameter of graphene oxide is 40-50 μm; (2) mixing 1 part of modified graphene oxide powder with 100 parts of silicone rubber raw rubber, 10 parts of aluminum oxide, 10 parts of sodium ascorbate, and 1 part of phosphite at 45° C. for 10 minutes to obtain modified raw rubber; (3) The modified raw rubber is mixed with 1 part of sulfur and 2 parts of CZ accelerator and then hot-pressed and vulcanized at 200°C to obtain a high-strength and highly antibacterial modified silicone rubber material.

[0033] The microstructure of the modified silicone rubber material is as follows: Figure 3 As shown, it is obvious that there are specific wrinkles, proving that the graphene oxide particles that have not been fumigated with water vapor cannot dissociate and return to sheets under the action of silica gel molecules. Its tensile strength is 4.54 MPa and its elongation at break is 134%. This is because graphene is still dispersed in particles and cannot effectively conduct external forces, and microscopic phase separation produces stress concentration points, which are more likely to produce tensile fractures. The antibacterial properties against Staphylococcus aureus, Escherichia coli and Candida albicans are 87%, 87% and 85% respectively, which are also significantly lower than Example 1. This is because the unfolded graphene oxide sheets cannot fully expose the surface groups, resulting in a decrease in the oxidative stress effect on bacteria, making it difficult to achieve efficient antibacterial.

Claims

1. A method for preparing a high-strength and highly antibacterial modified silicone rubber material, characterized in that: The steps include: (1) adding a silane coupling agent to a graphene oxide slurry, mixing the mixture evenly, and then spray drying the mixture to obtain a modified graphene oxide powder, wherein the mass ratio of the silane coupling agent to the graphene oxide is 0.5-3:10, and the concentration of the graphene oxide in the graphene oxide slurry is 3-15 mg / g; (2) fumigating the modified graphene oxide powder in a water vapor atmosphere to obtain water vapor-treated modified graphene oxide powder; (3) mixing 0.5-10 parts of the modified graphene oxide powder treated with water vapor with 100 parts of silicone rubber raw rubber, 10-30 parts of inorganic filler, 10 parts of sodium ascorbate, and 1-2 parts of antioxidant to obtain a modified raw rubber; (4) The modified raw rubber is mixed with 0.5 to 2 parts of sulfur and 2 to 3 parts of an accelerator and then hot-pressed and vulcanized to obtain a high-strength and highly antibacterial modified silicone rubber material.

2. The method according to claim 1, characterized in that The solvent of the graphene oxide slurry in step (1) is a mixture of one or more of water, DMF, DMSO, and NMP, and the flake diameter of the graphene oxide is 2 to 50 μm.

3. The method according to claim 1, characterized in that The silane coupling agent in step (1) contains one or more of an amino group, an epoxy group, and an isocyanate group.

4. The preparation method according to claim 1, characterized in that: The water vapor fumigation time in step (2) is 5 to 30 minutes, and the fumigation temperature is 90 to 120°C.

5. The preparation method according to claim 1, characterized in that: The antioxidant in step (3) is a phosphite antioxidant.

6. The preparation method according to claim 1, characterized in that: The inorganic filler in step (3) is a mixture of one or more of alumina, titanium dioxide, quartz powder, kaolin, talc, and calcium carbonate.

7. The preparation method according to claim 1, characterized in that: The mixing temperature in step (3) is 45 to 60° C., and the mixing time is 10 to 30 minutes.

8. The preparation method according to claim 1, characterized in that: The accelerator in step (4) is a sulfonamide accelerator.

9. The preparation method according to claim 1, characterized in that: The hot pressing vulcanization temperature in step (5) is 120-200°C.

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