A preparation process of silica gel bag

Abstract

The present application discloses a process for preparing a silica gel bag. The process for preparing the silica gel bag comprises the following steps: (1) stirring silica gel, fumed silica / graphene composite material, surface-modified carbon nanospheres, hydroxymethyl cellulose, and a curing agent at a stirring temperature of 60-80°C for a stirring time of 1-3 hours to obtain a mixture; (2) extruding the mixture obtained in step (1) to obtain a sheet, and transporting the sheet to an injection mold for injection molding at an injection temperature of 55-65°C for a time of 30-45 seconds; after the injection molding is completed, removing the mold core, closing the mold, and then inflating the mold core. After the inflation is completed, curing is performed at a curing temperature of 180-200°C for a curing time of 3-6 minutes to obtain a silica gel bag. The silica gel bag prepared in the present application has good mechanical properties, antibacterial properties, and long-lasting antibacterial properties.

Description

Technical Field

[0001] The present application relates to the technical field of silica gel products, and in particular to a preparation process of silica gel bags. Background Art

[0002] With the improvement of people's living standards, the application of silicone products is becoming more and more extensive, such as gloves, balloons, medical equipment, toys, packaging bags, etc. Therefore, people's requirements for silicone products are also getting higher and higher. Among them, silicone bags are promoted because they are easy to carry and do not take up space. Silicone bags are usually used to store various products such as vegetables, fruits, toys, electronic components, etc. Ordinary silicone bags are made of silicone as the main raw material. Silica gel, also known as silicic acid gel, is a highly active adsorption material. The main component of silica gel is silicon dioxide, which has stable chemical properties, is non-flammable, has a porous structure, strong adsorption, can be regenerated and reused, and is convenient for the storage and storage of items.

[0003] The existing production processes of silica gel bags are mostly single-process and complicated to operate. The silica gel products produced have average performance and do not have good antibacterial ability. When silica gel bags are used to store food, long-term storage will breed bacteria, which will cause the food to deteriorate and rot, thereby limiting the application scope of silica gel bags and making them difficult to promote widely. Summary of the Invention

[0004] In order to improve the problem of poor antibacterial performance of silica gel bags, the present application provides a preparation process of silica gel bags.

[0005] This application provides a preparation process for silica gel bags, which adopts the following technical solutions:

[0006] A preparation process for a silica gel bag comprises the following steps:

[0007] (1) stirring silica gel, fumed silica / graphene composite material, surface-modified carbon nanospheres, hydroxymethyl cellulose, and a curing agent at a stirring temperature of 60-80° C. for 1-3 h to obtain a mixture;

[0008] (2) Extruding the mixture obtained in step (1) to obtain a sheet, conveying the sheet to an injection mold for injection molding, with an injection molding temperature of 55-65°C and an injection molding time of 30-45s; after the injection molding is completed, removing the mold core, then closing the mold, and then inflating the mold core. After the inflation is completed, curing is performed, with a curing temperature of 180-200°C and a curing time of 3-6min to obtain a silica gel bag.

[0009] By adopting the above technical solution, silica gel, fumed silica / graphene composite material, surface-modified carbon nanospheres, hydroxymethyl cellulose and curing agent are evenly mixed, then extruded to prepare a sheet, and then the sheet is injection molded, and then the mold is closed, inflated and cured to obtain a silica gel bag. By limiting the raw materials that are matched with the silica gel and limiting the temperature and time in each step, a silica gel bag with better comprehensive performance is obtained.

[0010] Silica gel is an amorphous silicon dioxide with a porous structure, strong adsorption, a large specific surface area and good flexibility. The fumed silica / graphene composite material combines the respective properties of fumed silica and graphene, and has excellent mechanical properties and antibacterial properties. The surface-modified carbon nanospheres have excellent antibacterial and dispersibility. The mixture of silica gel, fumed silica / graphene composite material and surface-modified carbon nanospheres has good antibacterial and good biocompatibility, which can improve the antibacterial properties of silica gel and be prepared into silica gel bags with good antibacterial properties, which helps the silica gel bags to store food.

[0011] In addition, fumed silica has a small particle size, large specific surface area, strong surface adsorption and good dispersibility. It can be loaded on the surface of the graphene sheet structure, thereby enhancing the specific surface area of ​​the graphene and subsequently enhancing the mechanical properties of the silicone. In addition, the silicone molecular chain is easy to break and the intermolecular effect is relatively small. Adding silica to reinforce the silicone improves the intermolecular effect of the silicone, thereby enhancing the tensile strength, tear strength and toughness of the silicone.

[0012] Graphene is a new material composed of carbon atoms tightly stacked into a single-layer two-dimensional honeycomb lattice structure. It has a high specific surface area and high flexibility. Graphene loaded with fumed silica is mixed with silica gel. Fumed silica can be loaded in the porous structure of silica gel. At the same time, graphene can entangle with silica gel molecules, thereby enhancing the adhesion between the fumed silica / graphene composite material and the silica gel molecules, and further enhancing the tensile strength, tear strength and toughness of the silica gel molecules. Hydroxymethyl cellulose has a certain viscosity, and when combined with silica gel, it further enhances the viscoelasticity of silica gel, while helping to mix the components evenly and fuse the components with each other, thereby improving the comprehensive properties of silica gel such as mechanical properties and antibacterial properties.

[0013] Preferably, in parts by weight, the silica gel comprises 70-80 parts, the fumed silica / graphene composite material comprises 12-18 parts, the surface-modified carbon nanospheres comprises 5-10 parts, the hydroxymethyl cellulose comprises 3-8 parts, and the curing agent comprises 1-3 parts.

[0014] By adopting the above technical solution and further limiting the raw material components, a silica gel bag with excellent mechanical and antibacterial properties is obtained. The combination of fumed silica / graphene composite materials and surface-modified carbon nanospheres improves the antibacterial properties, tensile properties and tear strength of the silica gel material, while hydroxymethyl cellulose helps to mix the raw materials evenly, resulting in a silica gel bag with better performance.

[0015] Preferably, the method for preparing the fumed silica / graphene composite material comprises the following steps:

[0016] (1) dispersing graphene in an ethanol solution, ultrasonicating for 1-3 hours, then adding polylactic acid, ethylenediamine and silane coupling agent, and stirring at a temperature of 60-75° C. for 6-8 hours to obtain a mixture;

[0017] (2) mixing fumed silica, nano copper oxide, and microcrystalline wax, and stirring at a temperature of 80-90° C. for 30-45 minutes to obtain a second mixture;

[0018] (3) Mixing the mixture 1 obtained in step (1) and the mixture 2 obtained in step (2), stirring at a temperature of 90-105° C. for 60-80 min to obtain a mixture 3; placing the mixture 3 in a drying oven at 60-80° C. for 2-4 h to obtain a fumed silica / graphene composite material.

[0019] By adopting the above technical solution, graphene, polylactic acid, ethylenediamine and silane coupling agent are mixed, graphene has excellent mechanical properties and ultra-high specific surface area, polylactic acid has good biocompatibility, gloss, transparency and bacterial resistance, graphene is evenly dispersed in the polylactic acid matrix, graphene and polylactic acid molecular chains produce enhanced mechanical interlocking, and at the same time, the hydrogen bond between graphene and polylactic acid enhances the interface bonding between the two, further improving the tensile strength, tear strength and antibacterial properties of the composite material. In addition, the silane coupling agent is grafted onto the graphene surface to increase The spatial structure of graphene is changed, and the small molecule of ethylenediamine can adjust the spatial distance of the two-dimensional channels in graphene. Graphene changes the tissue microstructure and the spatial distance of the two-dimensional channels through cross-linking of ethylenediamine and silane coupling agent, and is filled with fumed silica and nano-copper oxide. Fumed silica has good mechanical properties, and nano-copper oxide has excellent adhesion and antibacterial properties, thereby increasing the mechanical properties and antibacterial properties of the composite material; microcrystalline wax has strong water and moisture permeability, bending resistance, plasticity and flexibility, thereby improving the comprehensive performance of the composite material and having a good protective effect.

[0020] Preferably, the mass ratio of the graphene, polylactic acid and fumed silica is 1:25-35:0.3-0.8.

[0021] By adopting the above technical solution, the mass ratio of graphene, polylactic acid and fumed silica is controlled to obtain a composite material with excellent mechanical properties and antibacterial properties. There is a synergistic effect between graphene, polylactic acid and fumed silica. Polylactic acid and graphene are combined to obtain a network structure, which increases the mechanical properties and antibacterial properties of graphene. Fumed silica is loaded in the network structure formed by polylactic acid and graphene, further increasing the mechanical properties of the composite material.

[0022] Preferably, the silane coupling agent is silane coupling agent KH570.

[0023] By adopting the above technical solution, silane coupling agent KH570 is used to prepare silica gel bags. Adding silane coupling agent KH570 can improve the adhesion to the silica gel material, increase water resistance, and reduce the curing temperature. Through the combination of covalent bonds and hydrogen bonds, silane is attached to the surface of the silica gel material, thereby playing a role in modifying the surface of the silica gel material.

[0024] Preferably, the method for preparing the surface-modified carbon nanospheres comprises the following steps:

[0025] (1) calcining the carbon nanospheres at a temperature of 300-400° C. for 1-3 h, then immersing them in malic acid for 1-3 h, and washing them with water to obtain pretreated carbon nanospheres;

[0026] (2) Dispersing the carbon nanospheres obtained in step (1) in a silver nitrate solution, stirring for 12-20 hours, then adding polyester fiber, thiol and dispersant, and continuing to stir for 30-50 minutes to obtain surface-modified carbon nanospheres.

[0027] By adopting the above technical solution, the carbon nanospheres have a microstructure with low density, high specific surface area and high pore volume. The carbon nanospheres are calcined at high temperature to remove organic impurities in the carbon nanospheres, further expand the pores of the carbon nanospheres, and increase the specific surface area of ​​the carbon nanospheres. Malic acid further removes organic impurities in the carbon nanospheres, thereby ensuring a large pore structure of the carbon nanospheres and increasing the dispersibility of the carbon nanospheres, which is conducive to the subsequent loading of silver ions.

[0028] Carbon nanospheres and silver nitrate are mixed so that silver ions are loaded on the carbon nanospheres, thereby increasing the antibacterial properties of the carbon nanospheres. Polyester fibers have high tensile strength, breaking strength and elasticity. Polyester fibers are adsorbed on the surface of the carbon nanospheres. At the same time, polyester fibers and silver ions adsorb each other. The carbon nanospheres and polyester fibers are entangled with each other to form a network structure, thereby increasing the probability of silver ion loading. Thiols further modify the carbon nanospheres. The carbon nanotube balls and thiol groups are covalently bonded, thereby increasing the molecular structure of the carbon nanospheres and the adsorption effect of the carbon nanospheres. This promotes the loading of silver ions and improves the mechanical properties and antibacterial properties of the carbon nanospheres.

[0029] Preferably, the usage ratio of the carbon nanospheres, silver nitrate solution and polyester fiber is 1 g:10-16 mL:0.3-0.9 g.

[0030] By adopting the above technical solution, the usage ratio of carbon nanospheres, silver nitrate and polyester fibers is controlled within a certain range, and surface-modified carbon nanospheres with excellent mechanical properties and antibacterial properties are obtained. There is a synergistic effect between the carbon nanospheres, silver nitrate and polyester fibers. Silver ions and polyester fibers are loaded on the carbon nanospheres, and silver ions are also loaded on the polyester fibers. The polyester fibers and carbon nanospheres are entangled with each other, increasing the spatial structure of the carbon nanospheres, which in turn helps to load the silver ions and further improve the mechanical properties and antibacterial properties of the carbon nanospheres.

[0031] Preferably, the dispersant is one or more of polyvinyl alcohol 1788, polyvinyl alcohol 124 and polyethylene glycol.

[0032] By adopting the above technical solution, the dispersant helps to disperse the graphene, solving the problem of agglomeration of graphene powder caused by Brownian motion and the polarity between particles.

[0033] Preferably, the curing agent is γ-aminopropyltrimethoxysilane and / or N-phenyl-γ-aminopropyltrimethoxysilane.

[0034] By adopting the above technical solution, the addition of the curing agent helps the curing and molding of the silicone bag, and is an additive that can solidify the liquid silicone.

[0035] Preferably, in step (2), the extrusion production temperature is: zone 1: 195-200°C, zone 2: 210-220°C, zone 3: 210-220°C, zone 4: 230-240°C, zone 5: 245-255°C, zone 6: 240-255°C, die head temperature: 245-255°C, material temperature: 250-260°C.

[0036] By adopting the above technical solution and setting a suitable extrusion temperature, it is helpful to obtain a uniformly mixed sheet.

[0037] In summary, this application has the following beneficial effects:

[0038] 1. In the present application, silica gel, fumed silica / graphene composite material, surface-modified carbon nanospheres, hydroxymethyl cellulose and a curing agent are mixed evenly, and then extruded to prepare a sheet, which is then injection molded, and then molded, inflated and cured to obtain a silica gel bag. By limiting the raw materials to be matched with the silica gel and limiting the temperature and time in each step, a silica gel bag with better comprehensive performance is obtained.

[0039] 2. The present application has a porous structure, strong adsorption, a large specific surface area, and good flexibility. The fumed silica / graphene composite material combines the respective properties of fumed silica and graphene, and has excellent mechanical properties and antibacterial properties. The surface-modified carbon nanospheres have excellent antibacterial and dispersibility. The mixture of silica gel, fumed silica / graphene composite material and surface-modified carbon nanospheres has good antibacterial and good biocompatibility, which can improve the antibacterial properties of silica gel and be prepared into silica gel bags with good antibacterial properties, which helps the silica gel bags to store food.

[0040] 3. The fumed silica in this application has a small particle size, a large specific surface area, strong surface adsorption and good dispersibility. It can be loaded on the surface of the graphene sheet structure, thereby enhancing the specific surface area of ​​the graphene and subsequently enhancing the mechanical properties of the silica gel. In addition, the silica gel molecular chain is easy to break and the intermolecular interaction is relatively small. The addition of silica gel can reinforce the silica gel, improve the interaction between silica gel molecules, and thereby enhance the tensile strength, tear strength and toughness of the silica gel. DETAILED DESCRIPTION

[0041] The present application is further described in detail below with reference to the embodiments.

[0042] The raw materials used in the examples and comparative examples can all be obtained commercially, wherein the silane coupling agent is silane coupling agent KH570, the dispersant is polyvinyl alcohol 1788, and the curing agent is γ-aminopropyltrimethoxysilane.

[0043] Preparation example of fumed silica / graphene composite material

[0044] Preparation Example 1-1

[0045] A method for preparing a fumed silica / graphene composite material comprises the following steps:

[0046] (1) 1 kg of graphene was dispersed in 2 L of ethanol solution, ultrasonicated for 3 h, and then polylactic acid, 0.1 kg of ethylenediamine and 0.03 kg of silane coupling agent were added, and stirred at 70 ° C for 7 h to obtain a mixture 1;

[0047] (2) Mix fumed silica, 0.01 kg of nano copper oxide, and 0.3 kg of microcrystalline wax, and stir at 85° C. for 35 minutes to obtain a second mixture;

[0048] (3) Mixing the mixture 1 obtained in step (1) and the mixture 2 obtained in step (2), stirring at a temperature of 100° C. for 70 minutes to obtain a mixture 3; placing the mixture 3 in a drying oven at 70° C. for 3 hours to obtain a fumed silica / graphene composite material, wherein the mass ratio of graphene, polylactic acid and fumed silica is 1:30:0.5.

[0049] Preparation Example 1-2

[0050] The difference from Preparation Example 1-1 is that polylactic acid is not added in step (1).

[0051] Preparation Examples 1-3

[0052] The difference from Preparation Example 1-1 is that in step (1), ethylenediamine is not added.

[0053] Preparation Examples 1-4

[0054] The difference from Preparation Example 1-1 is that the mass ratio of graphene, polylactic acid and fumed silica is 1:25:0.3.

[0055] Preparation Examples 1-5

[0056] The difference from Preparation Example 1-1 is that the mass ratio of graphene, polylactic acid and fumed silica is 1:35:0.8.

[0057] Preparation Examples 1-6

[0058] The difference from Preparation Example 1-1 is that the mass ratio of graphene, polylactic acid and fumed silica is 1:45:0.1.

[0059] Preparation Examples 1-7

[0060] The difference from Preparation Example 1-1 is that the mass ratio of graphene, polylactic acid and fumed silica is 1:15:1.2.

[0061] Preparation Examples 1-8

[0062] The difference from Preparation Example 1-1 is that in step (2), no nano copper oxide is added.

[0063] Preparation example of surface-modified carbon nanospheres

[0064] Preparation Example 2-1

[0065] The preparation method of surface-modified carbon nanospheres comprises the following steps:

[0066] (1) 1.2 kg of carbon nanospheres were calcined at 350 °C for 2 h, then immersed in 1.8 L of malic acid for 3 h, and washed with water to obtain pretreated carbon nanospheres;

[0067] (2) The carbon nanospheres obtained in step (1) were dispersed in a 0.1 mol / L silver nitrate solution and stirred for 18 h, and then polyester fiber, 0.2 kg of thiol and 0.05 kg of dispersant were added and stirred for 40 min to obtain surface-modified carbon nanospheres, wherein the amount ratio of carbon nanospheres, silver nitrate solution and polyester fiber was 1 g:14 mL:0.6 g.

[0068] Preparation Example 2-2

[0069] The difference from Preparation Example 2-1 is that in step (1), the carbon nanospheres are not calcined.

[0070] Preparation Example 2-3

[0071] The difference from Preparation Example 2-1 is that in step (1), polyester fiber is not added.

[0072] Preparation Example 2-4

[0073] The difference from Preparation Example 2-1 is that the usage ratio of carbon nanospheres, silver nitrate and polyester fiber is 1 g:16 mL:0.9 g.

[0074] Preparation Example 2-5

[0075] The difference from Preparation Example 2-1 is that the usage ratio of carbon nanospheres, silver nitrate and polyester fiber is 1 g:10 mL:0.3 g.

[0076] Preparation Example 2-6

[0077] The difference from Preparation Example 2-1 is that the usage ratio of carbon nanospheres, silver nitrate and polyester fiber is 1 g:6 mL:0.1 g.

[0078] Preparation Example 2-7

[0079] The difference from Preparation Example 2-1 is that the usage ratio of carbon nanospheres, silver nitrate and polyester fiber is 1 g:20 mL:1.2 g.

[0080] Preparation Example 2-8

[0081] The difference from Preparation Example 2-1 is that in step (2), no thiol is added.

[0082] Example

[0083] Example 1

[0084] A preparation process for a silica gel bag comprises the following steps:

[0085] (1) stirring silica gel, fumed silica / graphene composite material, surface-modified carbon nanospheres, hydroxymethyl cellulose, and a curing agent at a stirring temperature of 70° C. for 2 h to obtain a mixture;

[0086] (2) Extruding the mixture obtained in step (1) to obtain a sheet, and conveying the sheet to an injection mold for injection molding, with an injection molding temperature of 60° C. and an injection molding time of 40 s; after the injection molding is completed, removing the mold core, then closing the mold, and then inflating the mold core. After the inflation is completed, curing is performed, with a curing temperature of 190° C. and a curing time of 5 min to obtain a silica gel bag; in step (2), the extrusion production temperature is: zone 1: 195° C., zone 2: 210° C., zone 3: 220° C., zone 4: 230° C., zone 5: 245° C., zone 6: 255° C., die head temperature: 245° C., and material temperature: 260° C.

[0087] By weight, 75kg of silica gel, 16kg of fumed silica / graphene composite material, 8kg of surface-modified carbon nanospheres, 5kg of hydroxymethyl cellulose, and 2kg of curing agent;

[0088] The fumed silica / graphene composite material was prepared using Preparation Example 1-1; and the surface-modified carbon nanospheres were prepared using Preparation Example 2-1.

[0089] Example 2

[0090] A preparation process for a silica gel bag, which differs from Example 1 in that the fumed silica / graphene composite material is prepared using Preparation Example 1-2.

[0091] Example 3

[0092] A preparation process for a silica gel bag, which differs from Example 1 in that the fumed silica / graphene composite material is prepared using Preparation Examples 1-3.

[0093] Example 4

[0094] A preparation process for a silica gel bag, which differs from Example 1 in that the fumed silica / graphene composite material is prepared using Preparation Examples 1-4.

[0095] Example 5

[0096] A preparation process for a silica gel bag, which differs from Example 1 in that the fumed silica / graphene composite material is prepared using Preparation Examples 1-5.

[0097] Example 6

[0098] A preparation process for a silica gel bag, which differs from Example 1 in that the fumed silica / graphene composite material is prepared using Preparation Examples 1-6.

[0099] Example 7

[0100] A preparation process for a silica gel bag, which differs from Example 1 in that the fumed silica / graphene composite material is prepared using Preparation Examples 1-7.

[0101] Example 8

[0102] A preparation process for a silica gel bag, which differs from Example 1 in that the fumed silica / graphene composite material is prepared using Preparation Examples 1-8.

[0103] Example 9

[0104] A preparation process for a silica gel bag, which differs from Example 1 in that the surface-modified carbon nanospheres are prepared using Preparation Example 2-2.

[0105] Example 10

[0106] A preparation process for a silica gel bag is different from Example 1 in that the surface-modified carbon nanospheres are prepared using Preparation Example 2-3.

[0107] Example 11

[0108] A preparation process for a silica gel bag is different from Example 1 in that the surface-modified carbon nanospheres are prepared using Preparation Examples 2-4.

[0109] Example 12

[0110] A preparation process for a silica gel bag is different from Example 1 in that the surface-modified carbon nanospheres are prepared using Preparation Examples 2-5.

[0111] Example 13

[0112] A preparation process for a silica gel bag is different from Example 1 in that the surface-modified carbon nanospheres are prepared using Preparation Examples 2-6.

[0113] Example 14

[0114] A preparation process for a silica gel bag is different from Example 1 in that the surface-modified carbon nanospheres are prepared using Preparation Examples 2-7.

[0115] Example 15

[0116] A preparation process for a silica gel bag is different from Example 1 in that the surface-modified carbon nanospheres are prepared using Preparation Examples 2-8.

[0117] Example 16

[0118] A preparation process of a silica gel bag, which differs from Example 1 in that, by weight, 70 kg of silica gel, 12 kg of fumed silica / graphene composite material, 5 kg of surface-modified carbon nanospheres, 3 kg of hydroxymethyl cellulose, and 3 kg of curing agent are used.

[0119] Example 17

[0120] A preparation process of a silica gel bag, which differs from Example 1 in that, by weight, 80 kg of silica gel, 18 kg of fumed silica / graphene composite material, 10 kg of surface-modified carbon nanospheres, 8 kg of hydroxymethyl cellulose, and 1 kg of curing agent are used.

[0121] Example 18

[0122] A preparation process of a silica gel bag, which differs from Example 1 in that, by weight, 85 kg of silica gel, 8 kg of fumed silica / graphene composite material, 3 kg of surface-modified carbon nanospheres, 1 kg of hydroxymethyl cellulose, and 5 kg of curing agent are used.

[0123] Example 19

[0124] A preparation process of a silica gel bag, which differs from Example 1 in that, by weight, 60 kg of silica gel, 28 kg of fumed silica / graphene composite material, 15 kg of surface-modified carbon nanospheres, 10 kg of hydroxymethyl cellulose, and 0.5 kg of curing agent are used.

[0125] Comparative Example

[0126] Comparative Example 1

[0127] A preparation process for a silica gel bag, which differs from Example 1 in that no fumed silica / graphene composite material is added.

[0128] Comparative Example 2

[0129] A preparation process for a silica gel bag, which differs from Example 1 in that an equal amount of fumed silica is used instead of the fumed silica / graphene composite material.

[0130] Comparative Example 3

[0131] A preparation process for a silica gel bag, which differs from Example 1 in that an equal amount of graphene is used instead of the fumed silica / graphene composite material.

[0132] Comparative Example 4

[0133] A preparation process for a silica gel bag, which differs from Example 1 in that surface-modified carbon nanospheres are not added.

[0134] Comparative Example 5

[0135] A preparation process for a silica gel bag differs from that of Example 1 in that an equal amount of carbon nanospheres is used instead of the surface-modified carbon nanospheres.

[0136] Performance Testing The silica gel bags prepared in Examples 1-19 and Comparative Examples 1-5 were subjected to performance testing, wherein the tensile strength was tested according to GB / T1040-1992, the tear strength was tested according to QB / T1130-1991, and the antibacterial property was tested according to GB / T21510-2008. The results are shown in Table 1.

[0137] Table 1 Test data of embodiments and comparative examples

[0138]

[0139]

[0140] As can be seen from Table 1, the silica gel bags prepared in Examples 1, 4-5, 11-12 and 16-17 of the present application have good mechanical properties and antibacterial properties, with a tensile strength of 35 MPa, an elongation at break of 390%, a tear strength of 120 kN / m, an initial antibacterial rate of 99.8%, and an antibacterial rate of about 97.2% after 3 months of use. This shows that the prepared silica gel bags have excellent mechanical properties, antibacterial properties and antibacterial durability, which are helpful for the storage of food in silica gel bags.

[0141] In Example 2, polylactic acid is not added to the fumed silica / graphene composite material. As can be seen from Table 1, the prepared silica gel bag has a tensile strength of 24 MPa, an elongation at break of 379%, a tear strength of 109 kN / m, an initial antibacterial rate of 91.2%, and an antibacterial rate of 86.1% after 3 months of use, indicating that the addition of polylactic acid affects the mechanical properties and antibacterial properties of the fumed silica / graphene composite material, thereby affecting the comprehensive performance of the subsequent silica gel bag. Graphene is dispersed in the polylactic acid matrix, and produces enhanced mechanical interlocking with the polylactic acid molecular chain, thereby improving the tensile strength, tear strength and antibacterial properties of the composite material.

[0142] In Example 3, no ethylenediamine is added to the fumed silica / graphene composite material. As can be seen from Table 1, the tensile strength of the prepared silica gel bag is 29 MPa, the elongation at break is 383%, the tear strength is 115 kN / m, the initial antibacterial rate is 95.7%, and the antibacterial rate after 3 months of use is 91.1%. In Example 8, no nano-copper oxide is added in step (2), indicating that the addition of ethylenediamine and nano-copper oxide affects the mechanical properties of the fumed silica / graphene composite material. The small ethylenediamine molecule can adjust the spatial distance of the two-dimensional channel in the graphene. The graphene is cross-linked by ethylenediamine and silane coupling agent to change the microstructure of the tissue and the spatial distance of the two-dimensional channel, and the fumed silica and nano-copper oxide are filled in between, thereby improving the mechanical properties of the composite material.

[0143] In Examples 6-7, the mass ratio of graphene, polylactic acid and fumed silica is changed. Compared with Examples 1 and 2-5, the mechanical properties and antibacterial properties test data of the prepared silica gel bags are better than those of Examples 2-3, but worse than those of Examples 1 and 4-5, indicating that there is a synergistic effect between graphene, polylactic acid and fumed silica. Polylactic acid and graphene are combined to obtain a network structure, which increases the mechanical properties and antibacterial properties of graphene. Fumed silica is loaded in the network structure formed by polylactic acid and graphene, further increasing the mechanical properties of the composite material.

[0144] The carbon nanospheres in the surface-modified carbon nanospheres of Example 9 were not calcined. As can be seen from Table 1, the prepared silica gel bag had a tensile strength of 31 MPa, an elongation at break of 375%, a tear strength of 110 kN / m, an initial antibacterial rate of 90.1%, and an antibacterial rate of 85.4% after 3 months of use, indicating that calcination can remove organic impurities in the carbon nanospheres and further expand the pores of the carbon nanospheres, which is conducive to the subsequent loading of silver ions, thereby improving the antibacterial properties of the silica gel bag.

[0145] In Example 10, polyester fiber is not added to the surface-modified carbon nanospheres. As can be seen from Table 1, the prepared silica gel bag has a tensile strength of 25 MPa, an elongation at break of 380%, a tear strength of 109 kN / m, an initial antibacterial rate of 91.6%, and an antibacterial rate of 85.3% after 3 months of use. In Example 15, no thiol is added in step (2). The mechanical properties and antibacterial properties of the silica gel bag are significantly decreased compared with those in Example 1, indicating that polyester fiber has high tensile strength, breaking strength and elasticity. The polyester fiber is adsorbed on the surface of the carbon nanospheres, increasing the probability of silver ion loading. In addition, thiol further modifies the carbon nanospheres, and the carbon nanotube balls and thiol groups are covalently bonded, thereby increasing the molecular structure of the carbon nanospheres and increasing the adsorption effect of the carbon nanospheres, promoting the loading of silver ions, and thus improving the mechanical properties and antibacterial properties of the carbon nanospheres.

[0146] In Examples 13-14, the dosage ratio of carbon nanospheres, silver nitrate and polyester fibers was changed. Compared with Examples 1 and 9-12, the mechanical properties and antibacterial properties test data of the prepared silica gel bags were better than those of Examples 9-10, but worse than those of Examples 1 and 11-12, indicating that there was a synergistic effect between the carbon nanospheres, silver nitrate and polyester fibers. Silver ions and polyester fibers were loaded on the carbon nanospheres, and silver ions were also loaded on the polyester fibers. The polyester fibers and carbon nanospheres were entangled with each other, increasing the spatial structure of the carbon nanospheres, thereby contributing to the loading of silver ions and further improving the mechanical properties and antibacterial properties of the carbon nanospheres.

[0147] Examples 18-19 changed the amount of raw materials used in the preparation process of the silica gel bag. As can be seen from Table 1, compared with Example 1, the tensile strength, elongation at break, tear strength and antibacterial properties were greatly reduced, indicating that the silica gel bag has good mechanical strength, antibacterial properties and antibacterial durability when the raw material components are mixed according to a certain content ratio. The change in the amount of each raw material affects the comprehensive properties of the silica gel bag, such as mechanical properties and antibacterial properties.

[0148] Comparative Example 1 does not add the fumed silica / graphene composite material, and Comparative Example 4 does not add the surface-modified carbon nanospheres. As can be seen from Table 1, the tensile strength of the prepared silica gel bag reaches about 15 MPa, the elongation at break is about 350%, the tear strength is about 93 kN / m, the initial antibacterial rate is about 82%, and the antibacterial rate after 3 months of use is about 65%, indicating that the fumed silica / graphene composite material and surface-modified carbon nanospheres prepared in this application have good mechanical properties and antibacterial properties, and are subsequently used in the preparation of silica gel bags, thereby improving the mechanical properties, antibacterial properties and antibacterial durability of the silica gel bags.

[0149] In Comparative Example 2, an equal amount of fumed silica was used to replace the fumed silica / graphene composite material, in Comparative Example 3, an equal amount of graphene was used to replace the fumed silica / graphene composite material, and in Comparative Example 5, an equal amount of carbon nanospheres was used to replace the surface-modified carbon nanospheres. As can be seen from Table 1, the tensile strength, elongation at break, tear strength, antibacterial rate and antibacterial rate of the silica gel bag after 3 months of use were significantly reduced, but the performance test data were better than those of Comparative Example 1, indicating that the performance of the silica gel bag prepared by adding only fumed silica or graphene was far worse than that by adding the fumed silica / graphene composite material prepared in this application, indicating that the composite material prepared in this application has excellent comprehensive performance; the test data of Comparative Example 5 was worse than that of Example 1, indicating that the surface-modified carbon nanospheres modified in this application have excellent mechanical properties and antibacterial properties, and improve the comprehensive performance of the silica gel bag in the subsequent preparation of silica gel bags.

[0150] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A process for preparing a silica gel bag, characterized in that: The following steps are involved: (1) stirring silica gel, fumed silica / graphene composite material, surface-modified carbon nanospheres, hydroxymethyl cellulose and a curing agent at a stirring temperature of 60-80° C. for 1-3 h to obtain a mixture; (2) Extruding the mixture obtained in step (1) to obtain a sheet, conveying the sheet to an injection mold for injection molding at an injection temperature of 55-65°C and an injection time of 30-45 seconds; after the injection molding is completed, removing the mold core, closing the mold, and then inflating the mold core. After the inflation is completed, curing is performed at a curing temperature of 180-200°C and a curing time of 3-6 minutes to obtain a silica gel bag; The preparation method of the fumed silica / graphene composite material comprises the following steps: (1) Dispersing graphene in an ethanol solution, ultrasonicating for 1-3 hours, then adding polylactic acid, ethylenediamine and silane coupling agent, stirring at a temperature of 60-75°C for 6-8 hours to obtain a mixture; (2) Mix fumed silica, nano copper oxide, and microcrystalline wax, and stir at a temperature of 80-90° C. for 30-45 minutes to obtain a second mixture; (3) Mixing the mixture 1 obtained in step (1) and the mixture 2 obtained in step (2), stirring at a temperature of 90-105°C for 60-80 minutes to obtain a mixture 3; drying the mixture 3 in a drying oven at 60-80°C for 2-4 hours to obtain a fumed silica / graphene composite material; The preparation method of the surface-modified carbon nanospheres comprises the following steps: (1) calcining the carbon nanospheres at a temperature of 300-400°C for 1-3 hours, then immersing them in malic acid for 1-3 hours, and washing them with water to obtain pretreated carbon nanospheres; (2) The carbon nanospheres obtained in step (1) are dispersed in a silver nitrate solution and stirred for 12-20 hours, and then polyester fiber, thiol and dispersant are added and stirred for 30-50 minutes to obtain surface-modified carbon nanospheres.

2. The preparation process of a silica gel bag according to claim 1, characterized in that: In parts by weight, the silica gel comprises 70-80 parts, the fumed silica / graphene composite material comprises 12-18 parts, the surface-modified carbon nanospheres comprises 5-10 parts, the hydroxymethyl cellulose comprises 3-8 parts, and the curing agent comprises 1-3 parts.

3. The preparation process of a silica gel bag according to claim 1, characterized in that: The mass ratio of the graphene, polylactic acid and fumed silica is 1:25-35:0.3-0.

8.

4. The process for preparing a silica gel bag according to claim 1, characterized in that: The silane coupling agent is silane coupling agent KH570.

5. The process for preparing a silica gel bag according to claim 1, characterized in that: The usage ratio of the carbon nanospheres, the silver nitrate solution and the polyester fiber is 1 g:10-16 mL:0.3-0.9 g.

6. The process for preparing a silica gel bag according to claim 1, characterized in that: The dispersant is one or more of polyvinyl alcohol 1788, polyvinyl alcohol 124 and polyethylene glycol.

7. The process for preparing a silica gel bag according to claim 1, characterized in that: The curing agent is γ-aminopropyltrimethoxysilane and / or N-phenyl-γ-aminopropyltrimethoxysilane.

8. The process for preparing a silica gel bag according to claim 1, characterized in that: In step (2), the extrusion production temperature is: zone 1: 195-200°C, zone 2: 210-220°C, zone 3: 210-220°C, zone 4: 230-240°C, zone 5: 245-255°C, zone 6: 240-255°C, die head temperature: 245-255°C, material temperature: 250-260°C.

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