Preparation method of antibacterial starch-based material

Abstract

The invention discloses a preparation method of an antibacterial starch-based material, and belongs to the field of polymer composites.According to the preparation method, high amylose and high amylopectin are modified respectively and then compounded, components interact, the strength and toughness are balanced, the three-dimensional network density is increased, the mesh aperture is small, and migration of an antibacterial agent is reduced; besides, after the high amylose is modified, the surface hydrophobicity is improved, the adhesion of bacteria can be reduced, after the high amylose is modified, the high amylose also has a certain effect of inhibiting the growth of the bacteria, the starch-based material is endowed with remarkable antibacterial performance by combining the synergistic effect of the added antibacterial agent, and the binding force between the reinforcing agent and a starch molecular chain can be promoted by adding the reinforcing agent, so that the antibacterial property of the starch-based material is improved. The mechanical property of the starch-based material is remarkably improved, the hectorite can also remarkably improve the barrier property of the starch-based material, so that the starch-based material has better application performance, the uniformity of a matrix is promoted through the ultrasonic-assisted effect, and the overall mechanical property is more excellent.

Description

Technical Field

[0001] The invention relates to the technical field of polymer composite materials, and in particular to a method for preparing an antibacterial starch-based material. Background Art

[0002] Starch is a natural polymer that is abundant in source, cheap and environmentally friendly. Starch exists in the form of granules in the roots, stems, leaves, fruits and other organs of major crops such as cereals, beans and potatoes. The chemical structure of starch is (C4H l0 O5)n, which can be converted from maltose to glucose through gradual hydrolysis. Due to its advantages of being renewable, low-cost, and having good biocompatibility, it is widely used in food packaging, pharmaceutical carriers, and industrial materials. However, there are a large number of hydroxyl groups in starch molecules, and a large number of intramolecular and intermolecular hydrogen bonds between hydroxyl groups, which makes it difficult for starch molecular chains to move, resulting in poor mechanical properties and limiting its application.

[0003] In addition, natural starch lacks antibacterial properties and is susceptible to microbial contamination, which also limits its application. In order to better apply starch in the prior art, starch is modified, such as chitosan and starch are physically blended and modified to give the material certain antibacterial properties, but there is uneven dispersion, antibacterial component migration, resulting in poor antibacterial effect; another example is that plant essential oils are loaded on starch materials in the prior art, but there are shortcomings of poor stability, and even material incompatibility, making it difficult to exert more excellent antibacterial properties. For example, the Chinese patent application number CN202411346320.2 discloses an antibacterial sorghum starch-based film and a preparation method, by dissolving sorghum starch, adding glucose branching enzyme, inactivating the enzyme, adding pullulanase debranching and inactivating the enzyme, and gelatinizing the debranched sorghum starch; the gelatinized sorghum starch is mixed with glycerol, malic acid and prickly ash essential oil, freeze-dried, and a sorghum starch-based film is obtained, which has the problem that the antibacterial properties of the sorghum starch-based film are not durable.

[0004] Therefore, the starch-based materials in current technology have problems with poor mechanical properties and antibacterial properties. Summary of the invention

[0005] Based on this, in order to solve the problem that starch-based materials in the prior art have poor mechanical properties and antibacterial properties, the present invention provides a method for preparing an antibacterial starch-based material, and the specific technical scheme is as follows: A method for preparing an antibacterial starch-based material, the preparation method comprising the following steps: Adding high amylose starch to the dispersion under the first stirring condition, stirring and dispersing the mixture uniformly, adding epichlorohydrin under the first stirring condition, stirring for 20 min to 30 min, then adding methyl methacrylate and diisopropylbenzene peroxide, and continuing stirring at 70° C. to 80° C. for 1 h to 2 h to obtain modified starch A; Adding high-branched starch to the dispersion under the second stirring condition, stirring and dispersing uniformly, adding sodium hypochlorite under the second stirring condition, stirring for 15 minutes to 30 minutes, and then adding cysteine, stirring at 70° C. to 85° C. for 1 hour to 2 hours, to obtain modified starch B; The modified starch A and the modified starch B are mixed to obtain a mixed modified starch, and then an antibacterial agent is added under the third stirring condition, and the mixture is stirred for 10 min to 20 min. Then, a reinforcing agent and a cross-linking agent are added, and ultrasonic assistance is applied. Then, a compatibilizer and a plasticizer are added, and the mixture is stirred for 1 h to 2 h. After degassing, casting and drying, an antibacterial starch-based material is obtained.

[0006] Furthermore, the dispersion is obtained by mixing ethanol, sodium citrate and water in a volume ratio of (10-15):(1-2):50.

[0007] Furthermore, the weight ratio of the high-amylose starch, epichlorohydrin, methyl methacrylate and dicumyl peroxide is (15-20): (3-7): (1-5): (1-2).

[0008] Furthermore, the weight ratio of the high-branched starch, sodium hypochlorite and cysteine ​​is (15-20): (7-12): (1-5).

[0009] Furthermore, the mass ratio of the modified starch A to the modified starch B is (3~5):(5~7); the added amount of the antibacterial agent accounts for 1%~5% of the mass of the mixed modified starch; the added amount of the enhancer accounts for 1%~10% of the mass of the mixed modified starch; the added amount of the cross-linking agent accounts for 1%~2% of the mass of the mixed modified starch; the added amount of the compatibilizer accounts for 1%~3% of the mass of the mixed modified starch; and the added amount of the plasticizer accounts for 5%~12% of the mass of the mixed modified starch.

[0010] Furthermore, the preparation method of the antibacterial agent is: Polyhexamethyleneguanidine and 2-methoxyphenothiazine are added to an ethanol solution, heated to 55°C~65°C, and then aminosilane-modified mesoporous silica is added. The solution is vacuumed for 1min~5min, and then stirred at a speed of 100r / min~200r / min for 1h~3h. After drying and ball milling, an antibacterial agent is obtained.

[0011] Furthermore, the preparation method of the enhancer is: Methyltrimethoxysilane and hexadecyltrimethoxysilane are mixed to obtain a mixed solution, and then laponite and chopped activated carbon fibers are added to the mixed solution, stirred for 1 h to 2 h, and subjected to centrifugal, drying and ball milling treatments to obtain a reinforcing agent.

[0012] Furthermore, the cross-linking agent is at least one of citric acid, boric acid, glyoxal and glutaraldehyde.

[0013] Furthermore, the compatibilizer is at least one of polyvinyl alcohol, polycaprolactone, and linear low-density polyethylene grafted with glycidyl methacrylate.

[0014] Furthermore, the frequency of the ultrasonic-assisted effect is 15KHz~30KHz, the power is 50W~60W, and the time is 5min~15min.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention modifies high-amylose starch to obtain modified starch A, which forms a more excellent dense crystalline region and inhibits intermolecular hydrogen bonds, which helps to improve tensile strength. The modified starch B obtained by modifying high-branched starch has a highly branched structure that helps to improve elongation at break. After mixing, the two components interact with each other, which helps to balance strength and toughness, and the three-dimensional network density is increased, the mesh aperture is small, and the migration of antibacterial agents is reduced; in addition, after the high-amylose starch is modified, the surface hydrophobicity is improved, which can reduce bacterial attachment, and the high-branched starch also has a certain effect of inhibiting bacterial growth after modification.

[0016] 2. The present invention adds an antibacterial agent to give the starch-based material significant antibacterial properties, and the antibacterial agent is compounded with polyhexamethylene guanidine and 2-methoxyphenothiazine to achieve synergistic antibacterial properties. The adsorption of aminosilane-modified mesoporous silica can reduce the migration risk of the antibacterial agent, and can also be grafted with modified starch A and modified starch B. After multiple cross-linking, not only can the interaction between free hydroxyl groups on the starch molecular chain be effectively reduced, but the probability of migration of the effective ingredients can also be further reduced, and a certain sustained-release effect can be achieved, thereby achieving a long-term and stable antibacterial purpose. In addition, the antibacterial agent has better compatibility in the starch-based material and can also improve the mechanical properties of the starch-based material.

[0017] 3. The reinforcing agent prepared by the present invention forms an organic-inorganic hybrid structure, silane can promote the binding force between the reinforcing agent and the starch molecular chain, the compatibility is better, and the short-cut activated carbon fiber can be interlaced with the lithium soapstone, which significantly improves the mechanical properties of the starch-based material.

[0018] 4. The present invention promotes the uniformity of the material and the degree of cross-linking of the system through the ultrasound-assisted cavitation effect and mechanical vibration, which helps to further improve the mechanical properties and barrier properties of the starch-based material. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with its embodiments. It should be understood that the specific implementation methods described herein are only used to explain the present invention and do not limit the protection scope of the present invention.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0021] A method for preparing an antibacterial starch-based material in one embodiment of the present invention comprises the following steps: Adding high amylose starch to the dispersion under the first stirring condition, stirring and dispersing the mixture uniformly, adding epichlorohydrin under the first stirring condition, stirring for 20 min to 30 min, then adding methyl methacrylate and diisopropylbenzene peroxide, and continuing stirring at 70° C. to 80° C. for 1 h to 2 h to obtain modified starch A; Adding high-branched starch to the dispersion under the second stirring condition, stirring and dispersing uniformly, adding sodium hypochlorite under the second stirring condition, stirring for 15 minutes to 30 minutes, and then adding cysteine, stirring at 70° C. to 85° C. for 1 hour to 2 hours, to obtain modified starch B; The modified starch A and the modified starch B are mixed to obtain a mixed modified starch, and then an antibacterial agent is added under the third stirring condition, and the mixture is stirred for 10 min to 20 min. Then, a reinforcing agent and a cross-linking agent are added, and ultrasonic assistance is applied. Then, a compatibilizer and a plasticizer are added, and the mixture is stirred for 1 h to 2 h. After degassing, casting and drying, an antibacterial starch-based material is obtained.

[0022] In one embodiment, the dispersion is obtained by mixing ethanol, sodium citrate and water in a volume ratio of (10-15): (1-2): 50. The present invention configures a specific dispersion to promote uniform dispersion of starch in the dispersion and reduce agglomeration.

[0023] In one embodiment, when preparing modified starch A, the weight ratio of the high amylose starch to the dispersion is (15-20): (40-60).

[0024] In one embodiment, when preparing modified starch B, the weight ratio of the high-branched starch to the dispersion is (15-20): (40-60).

[0025] In one embodiment, the rotation speed of the first stirring condition is 300 r / min~500 r / min.

[0026] In one embodiment, the weight ratio of the high amylose starch, epichlorohydrin, methyl methacrylate and dicumyl peroxide is (15-20): (3-7): (1-5): (1-2).

[0027] In one embodiment, the rotation speed of the second stirring condition is 800 r / min~1500 r / min.

[0028] In one embodiment, the weight ratio of the high-branched starch, sodium hypochlorite and cysteine ​​is (15-20): (7-12): (1-5).

[0029] In one embodiment, the high amylose starch is high amylose corn starch with a molecular weight of (1.0-1.5)×10 5 Da.

[0030] In one embodiment, the high-branched starch is high-branched cassava starch with a molecular weight of (1.1-1.3)×10 8 Da.

[0031] In one embodiment, the content of amylose in the high-amylose corn starch is ≥80%.

[0032] In one embodiment, the content of amylopectin in the high-branched cassava starch is ≥80%.

[0033] In one embodiment, the mass ratio of the modified starch A and the modified starch B is (3~5):(5~7); the added amount of the antibacterial agent accounts for 1%~5% of the mass of the mixed modified starch; the added amount of the enhancer accounts for 1%~10% of the mass of the mixed modified starch; the added amount of the cross-linking agent accounts for 1%~2% of the mass of the mixed modified starch; the added amount of the compatibilizer accounts for 1%~3% of the mass of the mixed modified starch; and the added amount of the plasticizer accounts for 5%~12% of the mass of the mixed modified starch.

[0034] In one embodiment, the rotation speed of the third stirring condition is 500 r / min~1000 r / min.

[0035] In one embodiment, the preparation method of the antibacterial agent is: Polyhexamethyleneguanidine and 2-methoxyphenothiazine are added to an ethanol solution, heated to 55°C~65°C, and then aminosilane-modified mesoporous silica is added. The solution is vacuumed for 1min~5min, and then stirred at a speed of 100r / min~200r / min for 1h~3h. After drying and ball milling, an antibacterial agent is obtained.

[0036] In one embodiment, in the method for preparing the antibacterial agent, the volume ratio of ethanol to water in the ethanol solution is (3-5): (10-15).

[0037] In one embodiment, the weight ratio of the polyhexamethylene guanidine, 2-methoxyphenothiazine, ethanol solution and aminosilane-modified mesoporous silica is (1-5): (1-3): (15-30): (3-9).

[0038] In one embodiment, the specific surface area of ​​the aminosilane-modified mesoporous silica is >500 m² / g.

[0039] In one embodiment, the preparation method of the enhancer is: Methyltrimethoxysilane and hexadecyltrimethoxysilane are mixed to obtain a mixed solution, and then laponite and chopped activated carbon fibers are added to the mixed solution, stirred for 1 h to 2 h, and subjected to centrifugal, drying and ball milling treatments to obtain a reinforcing agent.

[0040] In one embodiment, the weight ratio of methyltrimethoxysilane, hexadecyltrimethoxysilane, hectorite and chopped activated carbon fibers is (10-30): (10-30): (1-5): (3-9).

[0041] In one embodiment, the average diameter of the hectorite is 25nm~30nm, and the thickness is 0.5nm~2nm.

[0042] In one embodiment, the average diameter of the chopped activated carbon fibers is 5 μm to 15 μm, and the length is 100 μm to 300 μm.

[0043] In one embodiment, the cross-linking agent is at least one of citric acid, boric acid, glyoxal and glutaraldehyde.

[0044] In one embodiment, the compatibilizer is at least one of polyvinyl alcohol, polycaprolactone, and linear low-density polyethylene grafted with glycidyl methacrylate.

[0045] In one embodiment, the plasticizer is at least one of glycerol, sorbitol, ethanol and acetyl tributyl citrate.

[0046] In one embodiment, the frequency of the ultrasonic assistance is 15KHz~30KHz, the power is 50W~60W, and the time is 5min~15min.

[0047] After the above scheme is optimized, a starch-based material with excellent mechanical and antibacterial properties can be obtained.

[0048] The embodiments of the present invention will be described in detail below with reference to specific examples. Embodiment 1:

[0049] A method for preparing an antibacterial starch-based material comprises the following steps: According to the weight ratio, 3 parts of polyhexamethylene guanidine and 3 parts of 2-methoxyphenothiazine were added to 20 parts of ethanol solution (the volume ratio of ethanol to water was 3:10), heated to 55°C, and then 8 parts of aminosilane-modified mesoporous silica were added, vacuumed for 1 minute, and then stirred at a speed of 100 r / min for 2 hours. After drying and ball milling, an antibacterial agent was obtained; According to the weight ratio, 15 parts of methyltrimethoxysilane and 15 parts of hexadecyltrimethoxysilane were mixed to obtain a mixed solution, and then 3 parts of hectorite and 7 parts of short-cut activated carbon fibers were added to the mixed solution, stirred for 1 hour, and subjected to centrifugal, drying and ball milling treatment to obtain a reinforcing agent; According to the weight ratio, 20 parts of high-amylose corn starch were added to 50 parts of dispersion (mixed by ethanol, sodium citrate and water in a volume ratio of 10:1:50) at a rotation speed of 300 r / min, and stirred to disperse evenly, and 5 parts of epichlorohydrin were added at 300 r / min, stirred for 25 minutes, and then 3 parts of methyl methacrylate and 1 part of diisopropylbenzene peroxide were added, and the stirring was continued at 75°C for 2 hours to obtain modified starch A; According to the weight ratio, 18 parts of high-branch cassava starch were added to 48 parts of dispersion liquid (mixed by ethanol, sodium citrate and water in a volume ratio of 10:1:50) at a rotation speed of 1000 r / min, and stirred and dispersed uniformly, and 7 parts of sodium hypochlorite were added at a rotation speed of 1000 r / min, and stirred for 30 minutes, and then 4 parts of cysteine ​​were added, and the stirring was continued at 80°C for 1 hour to obtain modified starch B; Modified starch A and modified starch B are mixed in a mass ratio of 4:6 to obtain a mixed modified starch, and then an antibacterial agent is added in an amount of 3% of the mass of the mixed modified starch at a rotation speed of 800 r / min, and the mixture is stirred for 15 minutes. Then, an enhancer is added in an amount of 5% of the mass of the mixed modified starch and citric acid is added in an amount of 1% of the mass of the mixed modified starch, and ultrasonic assistance is performed with a frequency of 20 KHz, a power of 50 W, and a time of 5 minutes. Then, polyvinyl alcohol is added in an amount of 1% of the mass of the mixed modified starch and glycerol is added in an amount of 8% of the mass of the mixed modified starch, and the mixture is stirred for 1 hour, followed by degassing, casting and drying to obtain an antibacterial starch-based material. Embodiment 2:

[0050] A method for preparing an antibacterial starch-based material comprises the following steps: According to the weight ratio, 4 parts of polyhexamethylene guanidine and 2 parts of 2-methoxyphenothiazine were added to 20 parts of ethanol solution (the volume ratio of ethanol to water was 3:10), heated to 60°C, and then 9 parts of aminosilane-modified mesoporous silica were added, vacuumed for 1 minute, and then stirred at a speed of 100 r / min for 2 hours. After drying and ball milling, an antibacterial agent was obtained; According to the weight ratio, 15 parts of methyltrimethoxysilane and 15 parts of hexadecyltrimethoxysilane were mixed to obtain a mixed solution, and then 4 parts of hectorite and 6 parts of short-cut activated carbon fibers were added to the mixed solution, stirred for 1 hour, and subjected to centrifugal, drying and ball milling treatment to obtain a reinforcing agent; According to the weight ratio, 19 parts of high-amylose corn starch were added to 50 parts of dispersion liquid (mixed by ethanol, sodium citrate and water in a volume ratio of 10:1:50) at a rotation speed of 300 r / min, and stirred to disperse evenly, and 6 parts of epichlorohydrin were added at 300 r / min, stirred for 30 minutes, and then 4 parts of methyl methacrylate and 1 part of diisopropylbenzene peroxide were added, and the stirring was continued at 75°C for 2 hours to obtain modified starch A; According to the weight ratio, 20 parts of high-branch cassava starch were added to 50 parts of dispersion liquid (mixed by ethanol, sodium citrate and water in a volume ratio of 10:1:50) at a rotation speed of 1000 r / min, and stirred to disperse evenly, and 8 parts of sodium hypochlorite were added at a rotation speed of 1000 r / min, and stirred for 30 minutes, and then 5 parts of cysteine ​​were added, and the stirring was continued at 85°C for 1 hour to obtain modified starch B; Modified starch A and modified starch B are mixed in a mass ratio of 5:5 to obtain a mixed modified starch, and then an antibacterial agent is added in an amount of 4% of the mass of the mixed modified starch at a rotation speed of 800 r / min, and the mixture is stirred for 20 minutes. Then, an enhancer is added in an amount of 4% of the mass of the mixed modified starch and citric acid is added in an amount of 1% of the mass of the mixed modified starch, and ultrasonic assistance is performed with a frequency of 20 KHz, a power of 50 W, and a time of 5 minutes. Then, polycaprolactone is added in an amount of 1% of the mass of the mixed modified starch and glycerol is added in an amount of 8% of the mass of the mixed modified starch, and the mixture is stirred for 1 hour, followed by degassing, casting and drying to obtain an antibacterial starch-based material. Embodiment 3:

[0051] A method for preparing an antibacterial starch-based material comprises the following steps: According to the weight ratio, 5 parts of polyhexamethylene guanidine and 1 part of 2-methoxyphenothiazine were added to 20 parts of ethanol solution (the volume ratio of ethanol to water was 3:10), heated to 55°C, and then 8 parts of aminosilane-modified mesoporous silica were added, vacuumed for 1 minute, and then stirred at a speed of 100 r / min for 2 hours. After drying and ball milling, an antibacterial agent was obtained; According to the weight ratio, 15 parts of methyltrimethoxysilane and 15 parts of hexadecyltrimethoxysilane were mixed to obtain a mixed solution, and then 4 parts of hectorite and 6 parts of short-cut activated carbon fibers were added to the mixed solution, stirred for 1 hour, and subjected to centrifugal, drying and ball milling treatment to obtain a reinforcing agent; According to the weight ratio, 18 parts of high-amylose corn starch were added to 48 parts of dispersion liquid (mixed by ethanol, sodium citrate and water in a volume ratio of 10:1:50) at a rotation speed of 300 r / min, and the mixture was evenly dispersed by stirring. Then, 7 parts of epichlorohydrin were added at a rotation speed of 300 r / min, and the mixture was stirred for 30 minutes. Then, 5 parts of methyl methacrylate and 1 part of diisopropylbenzene peroxide were added, and the mixture was stirred for 2 hours at 80°C to obtain modified starch A. According to the weight ratio, 20 parts of high-branch cassava starch were added to 50 parts of dispersion liquid (mixed by ethanol, sodium citrate and water in a volume ratio of 10:1:50) at a rotation speed of 1000 r / min, and stirred to disperse evenly, and 7 parts of sodium hypochlorite were added at a rotation speed of 1000 r / min, and stirred for 25 minutes, and then 5 parts of cysteine ​​were added, and the stirring was continued at 85°C for 1 hour to obtain modified starch B; Modified starch A and modified starch B are mixed in a mass ratio of 4:6 to obtain a mixed modified starch, and then an antibacterial agent is added in an amount of 5% of the mass of the mixed modified starch at a rotation speed of 1000 r / min, and the mixture is stirred for 20 minutes. Then, an enhancer is added in an amount of 4% of the mass of the mixed modified starch and citric acid is added in an amount of 1% of the mass of the mixed modified starch, and ultrasonic assistance is performed with a frequency of 20 KHz, a power of 50 W, and a time of 5 minutes. Then, polyvinyl alcohol is added in an amount of 1% of the mass of the mixed modified starch and glycerol is added in an amount of 10% of the mass of the mixed modified starch, and the mixture is stirred for 1 hour, followed by degassing, casting and drying to obtain an antibacterial starch-based material.

[0052] Comparative Example 1: The difference between Comparative Example 1 and Example 3 is that modified starch A is not added in Comparative Example 1, and the rest is the same as Example 3.

[0053] Comparative Example 2: The difference between Comparative Example 2 and Example 3 is that modified starch B is not added in Comparative Example 2, and the rest is the same as Example 3.

[0054] Comparative Example 3: The difference between Comparative Example 3 and Example 3 is that the high-branched cassava starch in Comparative Example 3 is not modified by cysteine, and the rest is the same as Example 3.

[0055] Comparative Example 4: The difference between Comparative Example 4 and Example 3 is that in Comparative Example 4, corn starch and cassava starch are mixed in a mass ratio of 4:6 to obtain mixed starch, and the rest is the same as Example 3. That is, the preparation method of the comparative sample in Comparative Example 4 is as follows: Corn starch and cassava starch are mixed in a mass ratio of 4:6 to obtain mixed starch, and then an antibacterial agent is added in an amount of 5% of the mass of the mixed modified starch at a rotation speed of 1000 r / min, and the mixture is stirred for 20 minutes. Then, an enhancer is added in an amount of 4% of the mass of the mixed modified starch and citric acid is added in an amount of 1% of the mass of the mixed modified starch, and ultrasonic assistance is performed with a frequency of 20 KHz, a power of 50 W, and a time of 5 minutes. Then, polyvinyl alcohol is added in an amount of 1% of the mass of the mixed modified starch and glycerol is added in an amount of 10% of the mass of the mixed modified starch, and the mixture is stirred for 1 hour, followed by degassing, casting and drying to obtain an antibacterial starch-based material.

[0056] Comparative Example 5: The difference between Comparative Example 5 and Example 3 is that polyhexamethylene guanidine is not added to the antibacterial agent of Comparative Example 5, and the rest is the same as Example 3.

[0057] Comparative Example 6: The difference between Comparative Example 6 and Example 4 is that 2-methoxyphenothiazine is not added to the antibacterial agent of Comparative Example 6, and the rest is the same as Example 3.

[0058] Comparative Example 7: The difference between Comparative Example 7 and Example 3 is that conventional silica is used in Comparative Example 7 to replace the aminosilane-modified mesoporous silica, and the rest is the same as Example 3.

[0059] Comparative Example 8: The difference between Comparative Example 8 and Example 3 is that no antibacterial agent is added in Comparative Example 8, and the rest is the same as Example 3.

[0060] Comparative Example 9: The difference between Comparative Example 9 and Example 3 is that the reinforcing agent in Comparative Example 9 is a single hectorite which is directly added and used, and the rest is the same as Example 3.

[0061] Comparative Example 10: The difference between Comparative Example 10 and Example 3 is that the reinforcing agent in Comparative Example 10 is a single chopped activated carbon fiber and is directly added for use, and the rest is the same as Example 3.

[0062] Comparative Example 11: The difference between Comparative Example 11 and Example 3 is that Comparative Example 11 is not subjected to ultrasonic assistance, and the rest is the same as Example 3.

[0063] The samples prepared in Examples 1 to 3 and the comparative samples prepared in Comparative Examples 1 to 11 were subjected to mechanical property tests and surface water contact angle tests, and the results are shown in Table 1 below.

[0064] The tensile strength and elongation at break were tested according to GB / T1040.3-2006. The water contact angle was tested using a wetting angle tester.

[0065] Table 1: Test results 1 Category Tensile strength / MPa Elongation at break / % Water contact angle / ° Example 1 48.9 68.7 96.4 Example 2 49.1 68.9 97.1 Example 3 49.2 69.2 97.3 Comparative Example 1 42.6 59.7 85.2 Comparative Example 2 40.7 51.8 81.7 Comparative Example 3 44.2 53.7 82.6 Comparative Example 4 26.7 30.4 73.8 Comparative Example 5 46.2 67.5 95.8 Comparative Example 6 44.5 53.7 95.3 Comparative Example 7 40.1 48.9 86.1 Comparative Example 8 36.9 43.1 85.5 Comparative Example 9 37.8 46.3 90.7 Comparative Example 10 39.4 49.1 89.8 Comparative Example 11 46.9 63.7 88.4 From the data analysis of Table 1, it can be seen that after the present invention is optimized by the composition, a starch-based material with excellent mechanical properties can be obtained as a whole, and the surface moisture adsorption can be reduced, which has a positive effect on antibacterial. Specifically, compared with Example 3, in Comparative Examples 1 to 4, due to the different starches used, the mechanical properties are obviously worse than those in Example 3, and in Comparative Example 4, due to the lack of modification, the surface is more likely to absorb moisture; the composition of the antibacterial agent in Comparative Examples 5 to 8 is different, and the mechanical properties and water resistance of the comparison samples are also worse than those in Example 3, indicating that the addition of the antibacterial agent has a certain effect on the mechanical properties and water resistance of the starch-based material; the composition of the reinforcing agent in Comparative Examples 9 to 10 is different, which has a significant effect on the mechanical properties of the material, indicating that the reinforcing agent added in this application also has a synergistic effect, which can significantly improve the mechanical properties of the material and have a certain effect on water resistance; Comparative Example 11 has not been ultrasonically assisted, but the mechanical properties of the material have decreased, and the water resistance is also worse than that of Example 3, indicating that the ultrasonic assisted effect can promote a more uniform matrix and help improve the mechanical properties. On the whole, this application is a complete technical solution. Through the optimization of components and processes, the components interact with each other to obtain starch-based materials with significant mechanical and antibacterial properties.

[0066] In addition, the samples of Examples 1 to 3 and the comparative samples of Comparative Examples 1 to 11 were tested for antibacterial performance and long-term antibacterial performance, and the results are shown in Table 2.

[0067] Antibacterial experiment: Escherichia coli was used as the test bacteria, and the antibacterial performance was tested according to the standard of QB / T2591-2003, using the film sticking method for testing. The contact time between the samples of Examples 1 to 3 and the comparative samples of Comparative Examples 1 to 11 and the test bacteria was 24 hours, respectively. The total colony count was determined according to the standard of GB / T4789.2-2003.

[0068] Long-term antibacterial test: The samples of Examples 1 to 3 and the comparative samples of Comparative Examples 1 to 11 were immersed in water, stirred at a temperature of 30° C., the water was changed every 12 hours, stirred for 15 days, and then the long-term antibacterial rate was tested.

[0069] Table 2: Test results 2 Group Antibacterial rate / % Long-term antibacterial rate / % Example 1 99.9 99.5 Example 2 99.9 99.7 Example 3 99.9 99.8 Comparative Example 1 94.8 90.6 Comparative Example 2 92.6 85.9 Comparative Example 3 97.2 90.3 Comparative Example 4 96.3 83.4 Comparative Example 5 83.4 76.1 Comparative Example 6 79.1 71.4 Comparative Example 7 91.6 82.4 Comparative Example 8 32.9 17.5 Comparative Example 9 99.2 91.3 Comparative Example 10 99.3 96.5 Comparative Example 11 99.5 98.1 From the data analysis of Table 2, it can be seen that after the composition is optimized, the density of the starch-based three-dimensional network formed in the present invention is increased, the mesh aperture is small, the migration of the antibacterial agent is reduced, and the antibacterial performance is more excellent. The modified treatment can further improve the antibacterial performance and antibacterial durability of the starch-based material. On the whole, the starch-based material has more significant antibacterial performance. After the antibacterial agent of the present application is grafted and cross-linked with the components in the system, the migration resistance is increased, and the durable antibacterial effect of the starch-based material can be further improved.

[0070] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing an antibacterial starch-based material, characterized in that: The preparation method comprises the following steps: Adding high amylose starch to the dispersion under the first stirring condition, stirring and dispersing the mixture uniformly, adding epichlorohydrin under the first stirring condition, stirring for 20 min to 30 min, then adding methyl methacrylate and diisopropylbenzene peroxide, and continuing stirring at 70° C. to 80° C. for 1 h to 2 h to obtain modified starch A; Adding high-branched starch to the dispersion under the second stirring condition, stirring and dispersing evenly, adding sodium hypochlorite under the second stirring condition, stirring for 15 minutes to 30 minutes, and then adding cysteine, stirring at 70° C. to 85° C. for 1 hour to 2 hours, to obtain modified starch B; The modified starch A and the modified starch B are mixed to obtain a mixed modified starch, and then an antibacterial agent is added under the third stirring condition, and the mixture is stirred for 10 min to 20 min. Then, a reinforcing agent and a cross-linking agent are added, and ultrasonic assistance is applied. Then, a compatibilizer and a plasticizer are added, and the mixture is stirred for 1 h to 2 h. After degassing, casting and drying, an antibacterial starch-based material is obtained.

2. The preparation method according to claim 1, characterized in that: The dispersion is obtained by mixing ethanol, sodium citrate and water in a volume ratio of (10-15):(1-2):

50.

3. The preparation method according to claim 1, characterized in that: The weight ratio of the high-amylose starch, epichlorohydrin, methyl methacrylate and dicumyl peroxide is (15-20): (3-7): (1-5): (1-2).

4. The preparation method according to claim 1, characterized in that: The weight ratio of the high-branched starch, sodium hypochlorite and cysteine ​​is (15-20): (7-12): (1-5).

5. The preparation method according to claim 1, characterized in that: The mass ratio of the modified starch A to the modified starch B is (3~5):(5~7); the added amount of the antibacterial agent accounts for 1%~5% of the mass of the mixed modified starch; the added amount of the enhancer accounts for 1%~10% of the mass of the mixed modified starch; the added amount of the cross-linking agent accounts for 1%~2% of the mass of the mixed modified starch; the added amount of the compatibilizer accounts for 1%~3% of the mass of the mixed modified starch; and the added amount of the plasticizer accounts for 5%~12% of the mass of the mixed modified starch.

6. The preparation method according to claim 1, characterized in that: The preparation method of the antibacterial agent is: Polyhexamethyleneguanidine and 2-methoxyphenothiazine are added to an ethanol solution, heated to 55°C~65°C, and then aminosilane-modified mesoporous silica is added. The solution is vacuumed for 1min~5min, and then stirred at a speed of 100r / min~200r / min for 1h~3h. After drying and ball milling, an antibacterial agent is obtained.

7. The preparation method according to claim 1, characterized in that: The preparation method of the enhancer is: Methyltrimethoxysilane and hexadecyltrimethoxysilane are mixed to obtain a mixed solution, and then laponite and chopped activated carbon fibers are added to the mixed solution, stirred for 1 h to 2 h, and subjected to centrifugal, drying and ball milling treatments to obtain a reinforcing agent.

8. The preparation method according to claim 1, characterized in that: The cross-linking agent is at least one of citric acid, boric acid, glyoxal and glutaraldehyde.

9. The preparation method according to claim 1, characterized in that: The compatibilizer is at least one of polyvinyl alcohol, polycaprolactone, and linear low-density polyethylene grafted with glycidyl methacrylate.

10. The preparation method according to claim 1, characterized in that: The frequency of ultrasonic assistance is 15KHz~30KHz, the power is 50W~60W, and the time is 5min~15min.