Preparation method of an antibacterial starch-based material

Abstract

The present invention discloses a preparation method of an antibacterial starch-based material, belonging to the field of polymer composite materials. In the present invention, high amylose starch and high amylopectin starch are respectively modified and then compounded. The components interact with each other, which helps to balance strength and toughness, and the three-dimensional network density increases, the grid pore size is small, reducing the migration of antibacterial agents. In addition, after the high amylose starch is modified, its surface hydrophobicity is improved, which can reduce bacterial attachment. After the high amylopectin starch is modified, it also has a certain effect of inhibiting bacterial growth. Combined with the addition of antibacterial agents and their synergistic effect, the starch-based material is endowed with significant antibacterial properties. The subsequent addition of reinforcing agents can promote the binding force between the reinforcing agents and the starch molecular chains, significantly improving the mechanical properties of the starch-based material. Moreover, lithium saponite can also significantly improve the barrier properties of the starch-based material, making it have better application performance. The ultrasonic-assisted effect promotes the uniformity of the matrix, and the overall mechanical properties are more excellent.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer composites, and more specifically, to a preparation method of an antibacterial starch-based material. Background Art

[0002] Starch is a natural polymer that is rich in sources, low in price, and environmentally friendly. Starch exists widely in the roots, stems, leaves, fruits and other organs of major crops such as cereals, legumes, and tubers in the form of granules. The chemical structural formula of starch is (C 4 H l0 O 5 )n, and it can be gradually hydrolyzed from maltose to glucose. Due to its advantages such as 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 there are 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 restricting its application.

[0003] In addition, natural starch lacks antibacterial properties and is vulnerable to microbial contamination, which also restricts its application. In the prior art, in order to better apply starch, starch is modified, such as physically blending and modifying chitosan with starch to endow the material with certain antibacterial properties, but there are problems such as uneven dispersion and migration of antibacterial components, resulting in poor antibacterial effects; another example is that plant essential oils are loaded on starch materials in the prior art, but there are disadvantages such as poor stability, and even material incompatibility, making it difficult to exert more excellent antibacterial properties. For example, the patent with 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 for debranching and then inactivating the enzyme, gelatinizing the debranched sorghum starch; adding glycerol, malic acid and Chinese prickly ash essential oil to the gelatinized sorghum starch and freeze-drying to obtain the sorghum starch-based film, and this sorghum starch-based film has the problem of non-persistent antibacterial performance.

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

[0005] Based on this, in order to solve the problems of poor mechanical properties and antibacterial properties of starch-based materials in the prior art, the present invention provides a preparation method of an antibacterial starch-based material, and the specific technical solution is as follows:

[0006] A preparation method of an antibacterial starch-based material, the preparation method includes the following steps:

[0007] Add high amylose starch to the dispersion liquid under the first stirring condition, stir and disperse evenly, add epichlorohydrin under the first stirring condition, stir and process for 20 min to 30 min, then add methyl methacrylate and diisopropylbenzene peroxide, and continue to stir and process at 70 °C to 80 °C for 1 h to 2 h to obtain modified starch A;

[0008] Add high-branched starch to the dispersion liquid under the second stirring condition, stir and disperse evenly, add sodium hypochlorite under the second stirring condition, stir and process for 15 min to 30 min, then add cysteine, and continue to stir and process at 70 °C to 85 °C for 1 h to 2 h to obtain modified starch B;

[0009] Mix the modified starch A and the modified starch B to obtain a mixed modified starch, then add an antibacterial agent under the third stirring condition, stir and process for 10 min to 20 min, then add a reinforcing agent and a crosslinking agent, with ultrasonic assistance, then add a compatibilizer and a plasticizer, stir and process for 1 h to 2 h, and after defoaming treatment, casting treatment and drying treatment, an antibacterial starch-based material is obtained.

[0010] Further, the dispersion liquid is obtained by mixing ethanol, sodium citrate and water with a volume ratio of (10 - 15):(1 - 2):50.

[0011] Further, the weight part ratio of the high amylose starch, epichlorohydrin, methyl methacrylate and diisopropylbenzene peroxide is (15 - 20):(3 - 7):(1 - 5):(1 - 2).

[0012] Further, the weight part ratio of the high-branched starch, sodium hypochlorite and cysteine is (15 - 20):(7 - 12):(1 - 5).

[0013] Further, the mass ratio of the modified starch A to the modified starch B is (3 - 5):(5 - 7); the addition amount of the antibacterial agent accounts for 1% - 5% of the mass of the mixed modified starch; the addition amount of the reinforcing agent accounts for 1% - 10% of the mass of the mixed modified starch; the addition amount of the crosslinking agent accounts for 1% - 2% of the mass of the mixed modified starch; the addition amount of the compatibilizer accounts for 1% - 3% of the mass of the mixed modified starch; the addition amount of the plasticizer accounts for 5% - 12% of the mass of the mixed modified starch.

[0014] Further, the preparation method of the antibacterial agent is:

[0015] Add polyhexamethylene guanidine and 2-methoxyphenothiazine to an ethanol solution, heat it to 55°C - 65°C, then add amino-silane-modified mesoporous silica, evacuate for 1 min - 5 min, and then stir at a rotation speed of 100 r / min - 200 r / min for 1 h - 3 h. After drying and ball milling, an antibacterial agent is obtained.

[0016] Further, the preparation method of the reinforcing agent is as follows:

[0017] Mix methyltrimethoxysilane and cetyltrimethoxysilane to obtain a mixed solution, then add lithium soapstone and short-cut activated carbon fibers to the mixed solution, stir for 1 h - 2 h, and after centrifugation, drying and ball milling, a reinforcing agent is obtained.

[0018] Further, the cross-linking agent is at least one of citric acid, boric acid, glyoxal and glutaraldehyde.

[0019] Further, the compatibilizer is at least one of polyvinyl alcohol, polycaprolactone, and linear low-density polyethylene grafted with glycidyl methacrylate.

[0020] Further, the frequency of the ultrasonic assistance is 15 KHz - 30 KHz, the power is 50 W - 60 W, and the time is 5 min - 15 min.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. In the present invention, high amylose starch is modified to obtain modified starch A, forming a more excellent dense crystalline region and inhibiting intermolecular hydrogen bonds, which helps to improve the tensile strength. Modified starch B obtained by modifying high amylopectin starch has a highly branched structure that helps to improve the 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 increases, the grid pore size is small, reducing the migration of the antibacterial agent; in addition, after the modification of high amylose starch, the surface hydrophobicity is improved, reducing bacterial adhesion, and after the modification of high amylopectin starch, it also has a certain effect of inhibiting bacterial growth.

[0023] 2. The present invention adds an antibacterial agent, endowing the starch-based material with significant antibacterial properties. The antibacterial agent is compounded with polyhexamethylene guanidine and 2-methoxyphenothiazine to have a synergistic antibacterial effect. Through the adsorption of amino-silane-modified mesoporous silica, the migration risk of the antibacterial agent can be reduced, and it can also be grafted with modified starch A and modified starch B. After multiple cross-linkings, not only the interaction between free hydroxyl groups on the starch molecular chain is effectively reduced, but also the probability of the migration of the active ingredient is further reduced, and a certain slow-release effect is achieved, achieving a long-term and stable antibacterial purpose; in addition, the antibacterial agent has more excellent compatibility in the starch-based material and can also improve the mechanical properties of the starch-based material.

[0024] 3. The reinforcing agent prepared by the present invention forms an organic-inorganic hybrid structure. The silane can promote the binding force between the reinforcing agent and the starch molecular chain, with more excellent compatibility. Moreover, the short-cut activated carbon fiber can interleave with the lithium saponite, significantly improving the mechanical properties of the starch-based material.

[0025] 4. Through the cavitation effect and mechanical vibration assisted by ultrasound in the present invention, the uniformity of the material is promoted and the crosslinking degree of the system is promoted, which helps to further improve the mechanical properties and barrier properties of the starch-based material. Specific Embodiments

[0026] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with its embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the protection scope of the present invention.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein 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 of the related listed items.

[0028] A preparation method of an antibacterial starch-based material in an embodiment of the present invention, the preparation method comprising the following steps:

[0029] Add high amylose starch to the dispersion liquid under the first stirring condition, stir and disperse evenly, add epichlorohydrin under the first stirring condition, stir and process for 20 min to 30 min, then add methyl methacrylate and diisopropylbenzene peroxide, and continue to stir and process at 70°C to 80°C for 1 h to 2 h to obtain modified starch A;

[0030] Add high-branched starch to the dispersion liquid under the second stirring condition, stir and disperse evenly, add sodium hypochlorite under the second stirring condition, stir and process for 15 min to 30 min, then add cysteine, and continue to stir and process at 70°C to 85°C for 1 h to 2 h to obtain modified starch B;

[0031] Mix the modified starch A and the modified starch B to obtain a mixed modified starch, then add an antibacterial agent under the third stirring condition, stir and process for 10 min to 20 min, then add a reinforcing agent and a crosslinking agent, with ultrasonic assistance, then add a compatibilizer and a plasticizer, stir and process for 1 h to 2 h, and after defoaming treatment, casting treatment and drying treatment, obtain the antibacterial starch-based material.

[0032] In one embodiment, the dispersion is obtained by mixing ethanol, sodium citrate, and water at a volume ratio of (10~15):(1~2):50. The present invention prepares a specific dispersion, which can promote the uniform dispersion of starch in the dispersion and reduce the phenomenon of aggregation.

[0033] In one embodiment, when preparing modified starch A, the weight ratio of the high amylose starch to the dispersion is (15~20):(40~60).

[0034] In one embodiment, when preparing modified starch B, the weight ratio of the high amylopectin starch to the dispersion is (15~20):(40~60).

[0035] In one embodiment, the rotation speed of the first stirring condition is 300 r / min to 500 r / min.

[0036] In one embodiment, the weight ratio of the high amylose starch, epichlorohydrin, methyl methacrylate, and diisopropylbenzene peroxide is (15~20):(3~7):(1~5):(1~2).

[0037] In one embodiment, the rotation speed of the second stirring condition is 800 r / min to 1500 r / min.

[0038] In one embodiment, the weight ratio of the high amylopectin starch, sodium hypochlorite, and cysteine is (15~20):(7~12):(1~5).

[0039] In one embodiment, the high amylose starch is high amylose corn starch with a molecular weight of (1.0~1.5)×10 5 Da.

[0040] In one embodiment, the high amylopectin starch is high amylopectin cassava starch with a molecular weight of (1.1~1.3)×10 8 Da.

[0041] In one embodiment, the content of amylose in the high amylose corn starch is ≥80%.

[0042] In one embodiment, the content of amylopectin in the high amylopectin cassava starch is ≥80%.

[0043] In one embodiment, the mass ratio of the modified starch A to the modified starch B is (3 - 5):(5 - 7); the addition amount of the antibacterial agent accounts for 1% - 5% of the mass of the mixed modified starch; the addition amount of the reinforcing agent accounts for 1% - 10% of the mass of the mixed modified starch; the addition amount of the cross-linking agent accounts for 1% - 2% of the mass of the mixed modified starch; the addition amount of the compatibilizer accounts for 1% - 3% of the mass of the mixed modified starch; the addition amount of the plasticizer accounts for 5% - 12% of the mass of the mixed modified starch.

[0044] In one embodiment, the rotation speed of the third stirring condition is 500 r / min - 1000 r / min.

[0045] In one embodiment, the preparation method of the antibacterial agent is as follows:

[0046] Add polyhexamethylene guanidine and 2-methoxyphenothiazine into an ethanol solution, heat it to 55°C - 65°C, then add amino-silane modified mesoporous silica, evacuate for 1 min - 5 min, and then stir and process at a rotation speed of 100 r / min - 200 r / min for 1 h - 3 h. After drying treatment and ball milling treatment, an antibacterial agent is obtained.

[0047] In one embodiment, in the preparation method of the antibacterial agent, the volume ratio of ethanol to water in the ethanol solution is (3 - 5):(10 - 15).

[0048] In one embodiment, the weight part ratio of polyhexamethylene guanidine, 2-methoxyphenothiazine, the ethanol solution and amino-silane modified mesoporous silica is (1 - 5):(1 - 3):(15 - 30):(3 - 9).

[0049] In one embodiment, the specific surface area of the amino-silane modified mesoporous silica > 500 m² / g.

[0050] In one embodiment, the preparation method of the reinforcing agent is as follows:

[0051] Mix methyltrimethoxysilane and cetyltrimethoxysilane to obtain a mixed solution, then add hectorite and short cut activated carbon fibers to the mixed solution, stir for 1 h - 2 h, and after centrifugation, drying and ball milling treatment, a reinforcing agent is obtained.

[0052] In one embodiment, the weight part ratio of methyltrimethoxysilane, cetyltrimethoxysilane, hectorite and short cut activated carbon fibers is (10 - 30):(10 - 30):(1 - 5):(3 - 9).

[0053] In one embodiment, the average diameter of the hectorite is 25 nm - 30 nm, and the thickness is 0.5 nm - 2 nm.

[0054] In one embodiment, the average diameter of the chopped activated carbon fiber is 5 μm to 15 μm, and the length is 100 μm to 300 μm.

[0055] In one embodiment, the crosslinking agent is at least one of citric acid, boric acid, glyoxal, and glutaraldehyde.

[0056] In one embodiment, the compatibilizer is at least one of polyvinyl alcohol, polycaprolactone, and linear low density polyethylene graft glycidyl methacrylate.

[0057] In one embodiment, the plasticizer is at least one of glycerol, sorbitol, ethanol, and tributyl acetylcitrate.

[0058] In one embodiment, the frequency of the ultrasonic assistance is 15 KHz to 30 KHz, the power is 50 W to 60 W, and the time is 5 min to 15 min.

[0059] After the above scheme is optimized, a starch-based material with excellent mechanical properties and antibacterial properties can be obtained.

[0060] The implementation scheme of the present invention will be described in detail below in conjunction with specific embodiments. Example 1:

[0061] A preparation method of an antibacterial starch-based material includes the following steps:

[0062] By weight ratio, add 3 parts of polyhexamethylene guanidine and 3 parts of 2-methoxyphenothiazine into 20 parts of an ethanol solution (the volume ratio of ethanol to water is 3:10), heat to 55 °C, then add 8 parts of amino-silane-modified mesoporous silica, evacuate for 1 min, and then stir at a speed of 100 r / min for 2 h. After drying treatment and ball milling treatment, an antibacterial agent is obtained;

[0063] By weight ratio, mix 15 parts of methyltrimethoxysilane and 15 parts of cetyltrimethoxysilane to obtain a mixed solution, then add 3 parts of lithium soapstone and 7 parts of chopped activated carbon fiber to the mixed solution, stir for 1 h, and after centrifugation, drying, and ball milling treatment, a reinforcing agent is obtained;

[0064] By weight ratio, add 20 parts of high amylose corn starch to 50 parts of a dispersion liquid (obtained by mixing ethanol, sodium citrate, and water in a volume ratio of 10:1:50) under the condition of a rotation speed of 300 r / min, stir and disperse evenly, and add 5 parts of epichlorohydrin under the condition of 300 r / min, stir for 25 min, then add 3 parts of methyl methacrylate and 1 part of diisopropylbenzene peroxide, and continue to stir at 75 °C for 2 h to obtain modified starch A;

[0065] By weight ratio, add 18 parts of high-branched tapioca starch to 48 parts of a dispersion (obtained by mixing ethanol, sodium citrate, and water in a volume ratio of 10:1:50) under the condition of a rotation speed of 1000 r / min, stir and disperse evenly, and under the condition of a rotation speed of 1000 r / min, add 7 parts of sodium hypochlorite, stir for 30 min, then add 4 parts of cysteine, and continue to stir at 80 °C for 1 h to obtain modified starch B;

[0066] Mix modified starch A and modified starch B with a mass ratio of 4:6 to obtain a mixed modified starch. Then, add an antibacterial agent with an addition amount accounting for 3% of the mass of the mixed modified starch under the condition of a rotation speed of 800 r / min, stir for 15 min, then add a reinforcing agent with an addition amount accounting for 5% of the mass of the mixed modified starch and citric acid with an addition amount accounting for 1% of the mass of the mixed modified starch. Carry out ultrasonic assistance with a frequency of 20 KHz, a power of 50 W, and a time of 5 min. Then add polyvinyl alcohol with an addition amount accounting for 1% of the mass of the mixed modified starch and glycerol with an addition amount accounting for 8% of the mass of the mixed modified starch, stir for 1 h, and then carry out defoaming treatment, casting treatment, and drying treatment to obtain an antibacterial starch-based material. Example 2:

[0067] A preparation method of an antibacterial starch-based material, comprising the following steps:

[0068] By weight ratio, add 4 parts of polyhexamethylene guanidine and 2 parts of 2-methoxyphenothiazine to 20 parts of an ethanol solution (the volume ratio of ethanol to water is 3:10), heat to 60 °C, then add 9 parts of amino-silane-modified mesoporous silica, evacuate for 1 min, and then stir at a rotation speed of 100 r / min for 2 h. After drying treatment and ball milling treatment, obtain an antibacterial agent;

[0069] By weight ratio, mix 15 parts of methyltrimethoxysilane and 15 parts of cetyltrimethoxysilane to obtain a mixed solution. Then, add 4 parts of lithium soapstone and 6 parts of short-cut activated carbon fibers to the mixed solution, stir for 1 h, and after centrifugation, drying, and ball milling treatment, obtain a reinforcing agent;

[0070] By weight ratio, add 19 parts of high-amylose corn starch to 50 parts of a dispersion (obtained by mixing ethanol, sodium citrate, and water in a volume ratio of 10:1:50) under the condition of a rotation speed of 300 r / min, stir and disperse evenly, and under the condition of 300 r / min, add 6 parts of epichlorohydrin, stir for 30 min, then add 4 parts of methyl methacrylate and 1 part of diisopropylbenzene peroxide, and continue to stir at 75 °C for 2 h to obtain modified starch A;

[0071] By weight ratio, 20 parts of high-branched cassava starch are added to 50 parts of a dispersion liquid (obtained by mixing ethanol, sodium citrate, and water in a volume ratio of 10:1:50) under the condition of a rotation speed of 1000 r / min, stirred and dispersed evenly, and under the condition of a rotation speed of 1000 r / min, 8 parts of sodium hypochlorite are added, stirred for 30 min, then 5 parts of cysteine are added, and stirring is continued at 85 °C for 1 h to obtain modified starch B;

[0072] Modified starch A and modified starch B with a mass ratio of 5:5 are mixed to obtain a mixed modified starch, and then an antibacterial agent with an addition amount accounting for 4% of the mass of the mixed modified starch is added under the condition of a rotation speed of 800 r / min, stirred for 20 min, then an enhancer with an addition amount accounting for 4% of the mass of the mixed modified starch and citric acid with an addition amount accounting for 1% of the mass of the mixed modified starch are added, ultrasonic assistance is carried out with a frequency of 20 KHz, a power of 50 W, and a time of 5 min, then polycaprolactone with an addition amount accounting for 1% of the mass of the mixed modified starch and glycerol with an addition amount accounting for 8% of the mass of the mixed modified starch are added, stirred for 1 h, and then defoaming treatment, casting treatment, and drying treatment are carried out to obtain an antibacterial starch-based material. Example 3:

[0073] A preparation method of an antibacterial starch-based material includes the following steps:

[0074] By weight ratio, 5 parts of polyhexamethylene guanidine and 1 part of 2-methoxyphenothiazine are added to 20 parts of an ethanol solution (the volume ratio of ethanol to water is 3:10), heated to 55 °C, then 8 parts of amino-silane-modified mesoporous silica are added, vacuum is pumped for 1 min, and then stirring treatment is carried out at a rotation speed of 100 r / min for 2 h, and after drying treatment and ball milling treatment, an antibacterial agent is obtained;

[0075] By weight ratio, 15 parts of methyltrimethoxysilane and 15 parts of cetyltrimethoxysilane are mixed to obtain a mixed liquid, then 4 parts of lithium soapstone and 6 parts of short-cut activated carbon fibers are added to the mixed liquid, stirred for 1 h, and after centrifugation, drying, and ball milling treatment, an enhancer is obtained;

[0076] By weight ratio, 18 parts of high-amylose corn starch are added to 48 parts of a dispersion liquid (obtained by mixing ethanol, sodium citrate, and water in a volume ratio of 10:1:50) under the condition of a rotation speed of 300 r / min, stirred and dispersed evenly, and under the condition of a rotation speed of 300 r / min, 7 parts of epichlorohydrin are added, stirred for 30 min, then 5 parts of methyl methacrylate and 1 part of diisopropylbenzene peroxide are added, and stirring is continued at 80 °C for 2 h to obtain modified starch A;

[0077] By weight ratio, 20 parts of high-branched cassava starch were added to 50 parts of a dispersion (obtained by mixing ethanol, sodium citrate, and water in a volume ratio of 10:1:50) under the condition of a rotation speed of 1000 r / min, stirred and dispersed evenly, and under the condition of a rotation speed of 1000 r / min, 7 parts of sodium hypochlorite were added, stirred for 25 min, then 5 parts of cysteine were added, and stirring was continued at 85 °C for 1 h to obtain modified starch B;

[0078] Modified starch A and modified starch B with a mass ratio of 4:6 were mixed to obtain a mixed modified starch. Then, under the condition of a rotation speed of 1000 r / min, an antibacterial agent with an addition amount accounting for 5% of the mass of the mixed modified starch was added, stirred for 20 min, then an enhancer with an addition amount accounting for 4% of the mass of the mixed modified starch and citric acid with an addition amount accounting for 1% of the mass of the mixed modified starch were added. Ultrasonic assistance was carried out with a frequency of 20 KHz, a power of 50 W, and a time of 5 min. Then, polyvinyl alcohol with an addition amount accounting for 1% of the mass of the mixed modified starch and glycerol with an addition amount accounting for 10% of the mass of the mixed modified starch were added, stirred for 1 h, and then defoaming treatment, casting treatment, and drying treatment were carried out to obtain an antibacterial starch-based material.

[0079] Comparative Example 1:

[0080] The difference between Comparative Example 1 and Example 3 is that modified starch A was not added in Comparative Example 1, and the others were the same as in Example 3.

[0081] Comparative Example 2:

[0082] The difference between Comparative Example 2 and Example 3 is that modified starch B was not added in Comparative Example 2, and the others were the same as in Example 3.

[0083] Comparative Example 3:

[0084] The difference between Comparative Example 3 and Example 3 is that the high-branched cassava starch in Comparative Example 3 was not modified with cysteine, and the others were the same as in Example 3.

[0085] Comparative Example 4:

[0086] The difference between Comparative Example 4 and Example 3 is that corn starch and cassava starch with a mass ratio of 4:6 were mixed to obtain a mixed starch, and the others were the same as in Example 3. That is, the preparation method of the comparative sample in Comparative Example 4 is as follows:

[0087] Mix corn starch and tapioca starch with a mass ratio of 4:6 to obtain mixed starch. Then, add an antibacterial agent with an addition amount of 5% of the mass of the mixed modified starch under the condition of a rotation speed of 1000 r / min, and stir for 20 min. Then, add a reinforcing agent with an addition amount of 4% of the mass of the mixed modified starch and citric acid with an addition amount of 1% of the mass of the mixed modified starch. Carry out ultrasonic assistance with a frequency of 20 KHz, a power of 50 W, and a time of 5 min. Then, add polyvinyl alcohol with an addition amount of 1% of the mass of the mixed modified starch and glycerol with an addition amount of 10% of the mass of the mixed modified starch, stir for 1 h, and then carry out defoaming treatment, casting treatment, and drying treatment to obtain an antibacterial starch-based material.

[0088] Comparative Example 5:

[0089] The difference between Comparative Example 5 and Example 3 is that polyhexamethylene guanidine is not added to the antibacterial agent in Comparative Example 5, and the others are the same as in Example 3.

[0090] Comparative Example 6:

[0091] The difference between Comparative Example 6 and Example 4 is that 2-methoxyphenothiazine is not added to the antibacterial agent in Comparative Example 6, and the others are the same as in Example 3.

[0092] Comparative Example 7:

[0093] The difference between Comparative Example 7 and Example 3 is that conventional silica is used to replace amino-silane-modified mesoporous silica in Comparative Example 7, and the others are the same as in Example 3.

[0094] Comparative Example 8:

[0095] The difference between Comparative Example 8 and Example 3 is that no antibacterial agent is added in Comparative Example 8, and the others are the same as in Example 3.

[0096] Comparative Example 9:

[0097] The difference between Comparative Example 9 and Example 3 is that the reinforcing agent in Comparative Example 9 is a single lithium saponite and is directly added for use, and the others are the same as in Example 3.

[0098] Comparative Example 10:

[0099] The difference between Comparative Example 10 and Example 3 is that the reinforcing agent in Comparative Example 10 is a single short-cut activated carbon fiber and is directly added for use, and the others are the same as in Example 3.

[0100] Comparative Example 11:

[0101] The difference between Comparative Example 11 and Example 3 is that ultrasonic assistance is not carried out in Comparative Example 11, and the others are the same as in Example 3.

[0102] 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.

[0103] Among them, the tests of tensile strength and elongation at break were carried out with reference to the standard GB / T1040.3-2006. The water contact angle was measured using a wetting angle tester.

[0104] Table 1: Test Results I

[0105] Group Items 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

[0106] It can be seen from the data analysis in Table 1 that after the composition of the present invention is optimized, a starch-based material with excellent mechanical properties can be obtained as a whole, and the surface water 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 use of different starches, the mechanical properties are significantly worse than those of Example 3, and in Comparative Example 4, due to the lack of modification, the surface is more likely to adsorb water; in Comparative Examples 5 to 8, the components of the antibacterial agent are different, and the mechanical properties and water resistance of the comparative samples are also worse than those of Example 3, indicating that the addition of the antibacterial agent has a certain impact on the mechanical properties and water resistance of the starch-based material; in Comparative Examples 9 to 10, the components of the reinforcing agent are different, which has an obvious impact on the mechanical properties of the material, indicating that the addition of the reinforcing agent in this application also has a synergistic effect, which can significantly improve the mechanical properties of the material and has a certain impact on the water resistance; Comparative Example 11 was not subjected to ultrasonic assistance, but the mechanical properties of the material decreased and the water resistance was also worse than that of Example 3, indicating that the ultrasonic assistance can promote the matrix to be more uniform and help improve the mechanical properties. As a whole, as a complete technical solution, after the composition and process of this application are optimized, the components interact with each other, and a starch-based material with remarkable mechanical properties and antibacterial properties can be obtained.

[0107] In addition, the antibacterial property tests and long-term antibacterial property tests were also carried out on the samples of Examples 1 to 3 and the comparative samples of Comparative Examples 1 to 11, and the results are shown in Table 2.

[0108] Antibacterial experiment: Escherichia coli was used as the test strain. The antibacterial property was detected according to the standard of QB / T2591-2003, and the film sticking method was used 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 strain was 24 h, and the determination of the total number of colonies was carried out according to the standard of GB / T4789.2-2003.

[0109] Long-term antibacterial experiment: The samples of Examples 1 to 3 and the comparative samples of Comparative Examples 1 to 11 were respectively immersed in water, stirred at a temperature of 30 °C, the water was changed every 12 h, stirred for 15 d, and then the long-term antibacterial rate was tested.

[0110] Table 2: Test Results II

[0111] 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

[0112] It can be seen from the data analysis in Table 2 that after the composition optimization of the present invention, a starch-based three-dimensional network with increased density and small grid pore size is formed, reducing the migration of the antibacterial agent, having more excellent antibacterial properties, and the modification treatment can further improve the antibacterial properties and antibacterial persistence of the starch-based material. Overall, it has a starch-based material with more remarkable excellent antibacterial properties. Moreover, after the antibacterial agent of the present application is grafted and crosslinked with the components in the system, the migration resistance increases, and it can also further improve the long-lasting antibacterial effect of the starch-based material.

[0113] The above-described embodiments merely represent several implementation manners of the present invention, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended 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 to 30 minutes, then adding methyl methacrylate and diisopropylbenzene peroxide, and continuing stirring at 70 to 80 degrees Celsius for 1 to 2 hours 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, then adding cysteine, and continuing to stir 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 to 20 minutes, and then a reinforcing agent and a cross-linking agent are added, and ultrasonic assistance is applied, and then a compatibilizer and a plasticizer are added, and the mixture is stirred for 1 to 2 hours, and an antibacterial starch-based material is obtained after degassing, casting and drying. The preparation method of the antibacterial agent is as follows: polyhexamethylene guanidine and 2-methoxyphenothiazine are added to an ethanol solution, heated to 55°C to 65°C, and then aminosilane-modified mesoporous silica is added, vacuuming for 1min to 5min, and then stirring at a speed of 100r / min to 200r / min for 1h to 3h, and drying and ball milling are performed to obtain the antibacterial agent; The preparation method of the reinforcing agent is as follows: 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 the reinforcing agent is obtained after centrifugation, drying and ball milling.

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 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; 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 cross-linking agent is at least one of citric acid, boric acid, glyoxal and glutaraldehyde.

7. 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.

8. 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.