Background
The adhesive tape industry is a technological industry which extends the ancient fine chemical technology and gradually carries out technological transformation, the product is extended from an adhesive tape nasal medical series adhesive tape and is divided into six series products of packaging series adhesive tape, label paper series adhesive tape, special adhesive tape and high-temperature-resistant series adhesive tape which are fashion computer spray painting series adhesive tape, the application field of the product is wide, and the product is widely covered by basic foods, medicines, sanitary materials, beauty and health products, five-way supplies, religious supplies, office equipment, photographic equipment, advertisements, printing, papermaking, shoemaking and spinning, and is widely developed into the industries of high-tech industries such as electronics, motors, communication equipment, petroleum industry, automobile industry, shipbuilding industry, aerospace industry and the like, and is one of the indispensable materials with large usage in daily life, but the development of the adhesive tape material is greatly restricted because the traditional adhesive tape product is mainly made of polyvinyl chloride and is difficult to recover and degrade. According to the incomplete statistics in 2019, the total length of the adhesive tape used in the express delivery field in China can reach 480 hundred million meters, which is equivalent to 1200 circles around the earth equator, and the huge use amount brings great pressure to the degradation treatment link.
The polylactic acid material is used as a bio-based environment-friendly material, has wide sources, mainly adopts corn, wheat and other crops, can be completely degraded into H2 O and CO2 in a period of months to years, has zero pollution to soil, and is a completely natural circulation type biodegradable material. The polylactic acid material can be applied in various fields, such as industry and agriculture, the polylactic acid mulching film can inhibit release of herbicide so as to protect crops, the polylactic acid material can be used for manufacturing heart stents, sterile non-woven fabrics and the like in the medical biology field, and the polylactic acid material has certain antibacterial performance due to the self structure in the clothing textile field and can be used for processing diaper, underwear and the like.
The chitosan is an alkaline cationic polysaccharide prepared by deacetylation of chitin, is a natural bacteriostatic agent, has broad spectrum, belongs to a green and environment-friendly biological bacteriostatic material, can promote tissue repair and wound healing, has rich sources, is nontoxic and pollution-free, has good biocompatibility and biodegradability, has strong broad-spectrum bacteriostatic performance, has good bactericidal effect on common pathogenic bacteria represented by escherichia coli, staphylococcus aureus, candida albicans and the like, and is mainly applied to industries such as food, medicine, agricultural seeds, daily chemical industry, industrial wastewater treatment and the like.
Polylactic acid and chitosan have good biocompatibility, degradability and absorbability, and modified products of the polylactic acid and the chitosan have been widely applied to the medical field. The slow release performance, mechanical property, biocompatibility, degradability and the like of the material can be regulated and controlled by changing the molecular structure and aggregation state morphology of the polymer, so that biomedical materials with different purposes are prepared.
Chinese patent CN113980598a discloses a method for preparing a PLA-based degradable adhesive tape, which comprises uniformly stirring a mixture containing polylactic acid (PLA), adipic acid-butylene terephthalate copolymer (PBAT), starch, a cross-linking agent and a plasticizer to obtain a mixture, extruding, blowing a film, drying to obtain a semi-finished film, using the semi-finished film as a base material layer of the adhesive tape, coating a release layer material on one side of the base material layer, preparing a release layer, coating an adhesive layer material on the other side of the base material layer, and preparing an adhesive layer. The degradable adhesive tape produced by the patent has the advantages of environmental protection, good water resistance and flexibility, but has the defects of single performance, no bacteriostasis and limitation in clinical medical application.
Chinese patent CN109749646a discloses a bacteriostatic single-layer non-woven fabric adhesive tape, which is formed by compounding a non-woven fabric layer and an adhesive layer, wherein the non-woven fabric is prepared by dipping a reverse 8-methyl-N-vanillyl-6-nonenylamide modified chitosan acidic solution, and the adhesive part consists of starch, compound modified nano tourmaline powder, succinic anhydride, hydrogen peroxide, sodium stearoyl lactate and deionized water. The preparation method has the advantages that the composite modified tourmaline powder is uniformly dispersed in the adhesive, so that the non-woven fabric adhesive tape has excellent antibacterial effect and antibacterial lasting effect, but has the defects that most non-woven fabrics are processed by polypropylene, natural degradation is difficult to realize, and sustainable development is not facilitated.
Chinese patent CN115141563a discloses a full-biodegradable adhesive tape and a preparation method thereof, wherein the substrate layer of the full-biodegradable adhesive tape is prepared from raw materials including poly adipic acid/butylene terephthalate, corn starch, poly propylene carbonate, plasticizer and coupling agent, the adhesive layer is prepared from raw materials including oxidized starch, diluent, cross-linking agent, thickener, titanium dioxide and water, and the release layer is silicone oil release agent. The adhesive tape has the advantages that the substrate layer and the adhesive layer of the adhesive tape are all biodegradable materials, the adhesive tape has basic physical properties, can be biodegradable, is environment-friendly and has no harm to the environment, but has the defects that the production process is complex, the antibacterial function is not realized, and the DMP, DEP, DOP contained in the plasticizer is the pollutant which is preferentially controlled by the environment in China and does not realize complete environment-friendly degradation.
Disclosure of Invention
The invention aims to provide an antibacterial adhesive tape based on the low polylactic acid, which has the characteristics of biodegradation and antibacterial property, is beneficial to environmental protection, can be applied to the fields of biomedicine, food packaging materials and the like, and simultaneously provides a preparation method of the antibacterial adhesive tape based on the low polylactic acid.
The antibacterial adhesive tape based on the low polylactic acid comprises a backing material, an adhesive layer and a release agent layer, wherein the adhesive layer is arranged on the upper surface of the backing material, the release agent layer is arranged on the lower surface of the backing material, the adhesive in the adhesive layer is antibacterial adhesive, and the antibacterial adhesive is prepared from the low polylactic acid, antibacterial polylactic acid, polyurethane elastomer, an antioxidant and a softener,
The preparation method of the antibacterial polylactic acid comprises the following steps:
(1) Under the protection of nitrogen, adding polylactic acid and a coupling agent into dichloromethane, stirring for reaction, and then cooling to room temperature to obtain a mixed solution;
(2) Adding diethyl ether into the mixed solution obtained in the step (1) to separate out solid powder, and carrying out suction filtration on the separated solid powder to obtain polylactic acid with carbonyl imidazole terminal groups;
(3) Under the protection of nitrogen, adding the polylactic acid with carbonyl imidazole end groups, chitosan and 4-dimethylaminopyridine obtained in the step (2) into dimethyl sulfoxide, stirring for reaction, cooling to room temperature, adding isopropanol to separate out solid powder, and performing suction filtration to obtain the antibacterial polylactic acid.
The molecular weight of the polylactic acid in the step (1) is 2 ten thousand-10 ten thousand.
The coupling agent in the step (1) is N, N' -Carbonyl Diimidazole (CDI).
The mass ratio of the polylactic acid to the coupling agent to the dichloromethane in the step (1) is 40-50:30-40:80-90.
The stirring reaction temperature in the step (1) is 30-60 ℃, and the stirring reaction time is 6-9h.
The mass ratio of the diethyl ether to the coupling agent in the step (2) is 40-50:30-40.
The mass ratio of the chitosan, the 4-dimethylaminopyridine, the dimethyl sulfoxide, the isopropanol and the polylactic acid in the step (3) is 30-40:1-2:30-40:30-40:40-50.
The stirring reaction temperature in the step (3) is 30-60 ℃, and the stirring reaction time is 36-72h.
The molecular weight of the oligomeric lactic acid is 600-1000.
The polyurethane elastomer is one or more of Toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI), p-phenylene diisocyanate (PPDI) or Naphthalene Diisocyanate (NDI).
The antioxidant is antioxidant 1076.
The softener is naphthenic oil KN-6.
The antibacterial adhesive is prepared from the following raw materials in parts by weight:
the preparation method of the antibacterial adhesive comprises the following steps:
(1) Heating and stirring the softener under the protection of nitrogen to obtain a preheated softener;
(2) Under the protection of nitrogen, adding the low polylactic acid, the antibacterial polylactic acid, the antioxidant and the polyurethane elastomer into the preheated softener obtained in the step (1), heating and mixing, discharging, and cooling to obtain the antibacterial adhesive.
The heating temperature in the step (1) is 80-100 ℃, and the stirring time is 0.5-2.5h.
The heating temperature in the step (2) is 100-120 ℃ and the mixing time is 1-3h.
The release agent in the release agent layer is methyl vinyl silicone rubber.
The backing material is a polylactic acid film.
The molecular weight of polylactic acid in the polylactic acid film is 5 ten thousand to 15 ten thousand, and the film thickness of the polylactic acid film is 0.05 to 0.15mm.
The preparation method of the antibacterial adhesive tape based on the oligomeric lactic acid comprises the steps of firstly coating a release agent on one surface of a backing material, then heating and softening an adhesive, coating the adhesive on the other surface of the backing material, cooling to room temperature, and solidifying to obtain the antibacterial adhesive tape based on the oligomeric lactic acid.
The release agent is coated on the backing material in an amount of 0.5-2.5g/m2.
The adhesive is coated on the backing material in an amount of 0.5-2.5g/m2.
The heating temperature is 95-105 ℃.
The antibacterial polylactic acid is prepared by performing a crosslinking reaction on polylactic acid and N, N' -Carbonyl Diimidazole (CDI) with high activity to obtain polylactic acid (PLA-CI) with carbonyl imidazole end groups, and then performing a further crosslinking reaction on PLA-CI and chitosan under the action of 4-Dimethylaminopyridine (DMAP) serving as a catalyst. Compared with polylactic acid, the antibacterial polylactic acid is chemically modified by chitosan with antibacterial activity, so that the antibacterial rate is improved. Compared with the physical blending composition of polylactic acid and chitosan, the invention adopts the coupling agent to connect the polylactic acid and the chitosan through covalent bonds, so that a material system is more stable, components are prevented from being physically separated out, and the antibacterial long-acting performance is improved.
The preparation mechanism of the antibacterial polylactic acid is as follows:
The invention adopts the low polylactic acid as the tackifier and the antibacterial polylactic acid as the antibacterial active component. Wherein the antibacterial polylactic acid is prepared by connecting chitosan to polylactic acid through a covalent bond. If chitosan is used alone, the chitosan has poor compatibility with other components, phase separation is easy to occur, and the chitosan is easy to separate out. After the chitosan is connected to the polylactic acid, the polylactic acid has good compatibility with other components, and the chitosan can be well dispersed in an adhesive system under the belt of the polylactic acid structure, so that the problems of phase separation and precipitation are solved. The polylactic acid and the oligomeric lactic acid have the same chemical structure and different molecular weights, the oligomeric lactic acid has small molecular weight and strong fluidity, and the use of the oligomeric lactic acid is beneficial to further improving the dispersibility and the intersolubility of the antibacterial polylactic acid. The formula system with the synergistic effect of the oligomeric lactic acid and the antibacterial polylactic acid not only can obtain the adhesive tape material with stable physical and chemical properties, but also has good antibacterial activity and antibacterial long-acting property. The raw materials used for preparing the adhesive tape have good degradability, so that the prepared adhesive tape also has good degradability, and is convenient for post-treatment after the adhesive tape is used, thereby not only meeting the special requirements in the fields of medical and health, packaging materials and the like, but also reducing environmental burden and meeting the requirement of sustainable development.
The beneficial effects of the invention are as follows:
(1) The surface of chitosan contains a large number of active groups such as amino groups, hydroxyl groups and the like, one of the end groups of polylactic acid is hydroxyl, an active site is provided for the crosslinking reaction, and the two groups of polylactic acid and the active site can be combined through a covalent bond by a coupling agent to obtain the antibacterial polylactic acid with stable chemical structure, so that the antibacterial activity of the polylactic acid is improved.
(2) The antibacterial polylactic acid and the oligomeric lactic acid adopted by the invention have the same polylactic acid structure, have good intersolubility according to the principle of similar compatibility, have small molecular weight and strong fluidity, and adopt a formula system with synergistic action of the antibacterial polylactic acid and the polylactic acid, thereby being beneficial to improving the uniformity and the stability of the adhesive and being beneficial to regulating and controlling the viscoelasticity of the adhesive so as to obtain good bonding performance.
(3) The antibacterial adhesive tape based on the oligomeric lactic acid, which is prepared by the invention, relates to degradable materials, has good biological activity while maintaining stable chemical properties and physical properties, can be degraded in natural environment, is an environment-friendly practical high polymer material, and is suitable for wide popularization and application.
Detailed Description
The invention is further described below with reference to examples.
Example 1
The preparation method of the antibacterial polylactic acid comprises the following steps:
(1) 40 parts of polylactic acid (molecular weight: 3 ten thousand) and 30 parts of coupling agent CDI were dissolved in 80 parts of methylene chloride under the protection of nitrogen, reacted for 8 hours under stirring at 50 ℃, and then cooled to room temperature to obtain a mixed solution.
(2) Adding 40 parts of diethyl ether into the mixed solution obtained in the step (1) to precipitate solid powder, and carrying out suction filtration on the precipitated solid powder to obtain polylactic acid (PLA-CI) with carbonyl imidazole terminal groups.
(3) And (3) under the protection of nitrogen, dissolving the PLA-CI obtained in the step (2), 30 parts of chitosan and1 part of 4-Dimethylaminopyridine (DMAP) in 35 parts of dimethyl sulfoxide (DMSO), stirring at 50 ℃ for reaction for 48 hours, cooling to room temperature, adding 40 parts of isopropanol to separate out solid powder, and carrying out suction filtration to obtain the antibacterial polylactic acid.
The composition of the bacteriostatic adhesive is shown in table 1.
Table 1 composition of bacteriostatic adhesive of example 1
The preparation method of the antibacterial adhesive comprises the following steps:
(1) Under the protection of nitrogen, adding naphthenic oil KN-6 into a reaction vessel, heating to 100 ℃, and stirring for 2 hours to obtain preheated naphthenic oil KN-6;
(2) Under the protection of nitrogen, adding the oligomeric lactic acid, the antibacterial polylactic acid, the antioxidant 1076 and the polyurethane elastomer (the mass ratio of TDI to MDI is 2:1) into the preheated naphthenic oil KN-6 obtained in the step (1), heating to 100 ℃, mixing for 2 hours, discharging, and cooling to obtain the antibacterial adhesive.
The preparation method of the antibacterial adhesive tape based on the oligomeric lactic acid comprises the following steps:
(1) Coating a release agent on one surface of a polylactic acid film backing material by using a coating machine, wherein the coating amount is 0.5g/m2, the molecular weight of polylactic acid in the polylactic acid film is 5 ten thousand, and the film thickness of the polylactic acid film is 0.05mm;
(2) And heating the antibacterial adhesive to 100 ℃ for softening, coating the antibacterial adhesive on the other side of the backing material, wherein the coating amount is 0.5g/m2, and cooling and solidifying at room temperature to obtain the antibacterial adhesive tape based on the polylactic acid.
Annular initial adhesion test the annular initial adhesion of the tape was measured to be 7.63N using GB/T31125-2014.
180 DEG peel force Using GB/T2792-2014, the 180 DEG peel force of the tape was measured to be 0.569kgf.
Aging degradation test 1cm square with a thickness of 0.1mm was prepared and placed in a small glass bottle of phosphate buffer solution (Tris-HCl buffer system) with pH=8.0, the concentration of proteinase K (Genview) in the bottle was 0.2mg/ml, the temperature was set at 45℃and the shaking speed was 140 rpm. Samples were taken at specified time intervals, washed with distilled water, dried under vacuum until constant weight, and then the mass of the samples was measured. The weight loss rate (WL) of the sample was calculated by the following formula: Where mo is the weight of the sample before degradation and mi is the weight of the sample after degradation. The ML after 7 days of degradation was found to be 76% and the ML after 30 days of degradation was found to be 89%.
Antibacterial property test, cutting the adhesive tape into a disc (phi 10.0 cm), washing and drying the adhesive layer, and detecting antibacterial properties of the adhesive layer of the disc against three bacteria by a film adhesion method, wherein the used bacteria are staphylococcus aureus (S.aureus ATCC 29213), escherichia coli (E.coli ATCC 25922) and candida albicans (C.albicans ATCC 10231). Firstly, mixing the freeze-dried bacteria of each strain by using a Sahnikovia culture solution, taking 2ml of bacterial suspension, culturing for 24 hours at a constant temperature of 37 ℃, and completing the activation of the freeze-dried bacteria after 2 times of transfer by using an inoculating loop. Then, 1X 105 CFU/mL of bacterial suspension is prepared by a Maillard turbidimetry method, 0.2mL of diluted bacterial suspension is dripped on the surface of a sample of a tape wafer to be detected, a sterilized polyethylene film is covered, and the solution is subjected to anaerobic culture at 37 ℃ for 48 hours (80% N2,10％CO2,10％ H2). Finally, the tape wafer sample and polyethylene film were eluted thoroughly with 20mL of 0.9% NaCl aqueous solution, after shaking up, 500. Mu.L of the eluate was inoculated into TSA medium, and after culturing for 24 hours, colonies were counted. And repeatedly detecting each group of adhesive tape wafer samples for 5 times, and taking a colony counting average value to calculate the bacteriostasis rate, wherein the bacteriostasis rate is = (the number of recovered bacteria of a blank control sample-the number of recovered bacteria of an experimental group sample)/the number of recovered bacteria of the blank control sample is multiplied by 100%. The antibacterial rate of S.aureus is 97.32%, the antibacterial rate of E.coli is 97.10% and the antibacterial rate of C.albicans is 96.69% for the newly prepared adhesive tape. And (3) carrying out an accelerated ageing experiment on the adhesive tape sample, namely storing the adhesive tape sample in a 55 ℃ incubator for 21 days, taking out, and repeating the antibacterial performance test to obtain that the antibacterial rate of S.aureus of the adhesive tape after 21 days of ageing is 94.45%, the antibacterial rate of E.coll is 93.26% and the antibacterial rate of C.albicans is 93.07%.
Example 2
The preparation method of the antibacterial polylactic acid comprises the following steps:
(1) 40 parts of polylactic acid (molecular weight: 6 ten thousand) and 30 parts of CDI as a coupling agent were dissolved in 80 parts of methylene chloride under nitrogen protection, reacted for 7 hours under stirring at 40 ℃, and then cooled to room temperature to obtain a mixed solution.
(2) 50 Parts of diethyl ether is added into the mixed solution obtained in the step (1) to precipitate solid powder, and the precipitated solid powder is subjected to suction filtration to obtain polylactic acid (PLA-CI) with carbonyl imidazole terminal groups.
(3) And (3) under the protection of nitrogen, dissolving the PLA-CI obtained in the step (2), 40 parts of chitosan and 2 parts of 4-Dimethylaminopyridine (DMAP) in 40 parts of dimethyl sulfoxide (DMSO), stirring at 50 ℃ for reaction for 48 hours, cooling to room temperature, adding 40 parts of isopropanol, precipitating solid powder, and carrying out suction filtration to obtain the antibacterial polylactic acid.
The composition of the bacteriostatic adhesive is shown in table 2.
TABLE 2 composition of bacteriostatic adhesive of example 2
The preparation method of the antibacterial adhesive comprises the following steps:
(1) Under the protection of nitrogen, adding naphthenic oil KN-6 into a reaction vessel, heating to 90 ℃ and stirring for 1.5h to obtain preheated naphthenic oil KN-6;
(2) Under the protection of nitrogen, adding the oligomeric lactic acid, the antibacterial polylactic acid, the antioxidant 1076 and the TDI into the preheated naphthenic oil KN-6 obtained in the step (1), heating to 150 ℃, mixing for 1h, discharging, and cooling to obtain the antibacterial adhesive.
The preparation method of the antibacterial adhesive tape based on the oligomeric lactic acid comprises the following steps:
(1) Coating a release agent on one surface of a polylactic acid film backing material by using a coating machine, wherein the coating amount is 1.5g/m2, the molecular weight of polylactic acid in the polylactic acid film is 8 ten thousand, and the film thickness of the polylactic acid film is 0.1mm;
(2) And heating the antibacterial adhesive to 95 ℃ for softening, coating the antibacterial adhesive on the other side of the backing material, wherein the coating amount is 1.5g/m2, and cooling and solidifying at room temperature to obtain the antibacterial adhesive tape based on the polylactic acid.
Ring-shaped primary adhesion test the test method was the same as in example 1. The annular primary adhesion was measured to be 7.49N;
180 ° peel force test method was the same as in example 1. 180 ° peel force was measured to be 0.557kgf;
degradation by aging test the test method was the same as in example 1. The ML after 7 days of degradation was found to be 70% and the ML after 30 days of degradation was found to be 88%.
Antibacterial property test the test method was the same as in example 1. The antibacterial rate of S.aureus is 97.89%, the antibacterial rate of E.coli is 98.01%, and the antibacterial rate of C.albicans is 97.69% for the newly prepared adhesive tape. The antibacterial rate of S.aureus of the adhesive tape after 21 days of aging is 95.19%, the antibacterial rate of E.coli is 94.13%, and the antibacterial rate of C.albicans is 94.72%.
Example 3
The preparation method of the antibacterial polylactic acid comprises the following steps:
(1) 40 parts of polylactic acid (molecular weight: 8 ten thousand) and 40 parts of coupling agent CDI were dissolved in 90 parts of methylene chloride under the protection of nitrogen, reacted for 9 hours under stirring at 60 ℃, and then cooled to room temperature to obtain a mixed solution.
(2) 50 Parts of diethyl ether is added into the mixed solution obtained in the step (1) to precipitate solid powder, and the precipitated solid powder is subjected to suction filtration to obtain polylactic acid (PLA-CI) with carbonyl imidazole terminal groups.
(3) And (3) under the protection of nitrogen, dissolving the PLA-CI obtained in the step (2), 40 parts of chitosan and 2 parts of 4-Dimethylaminopyridine (DMAP) in 40 parts of dimethyl sulfoxide (DMSO), stirring at 60 ℃ for reaction for 72 hours, cooling to room temperature, adding 40 parts of isopropanol, precipitating solid powder, and carrying out suction filtration to obtain the antibacterial polylactic acid.
The composition of the bacteriostatic adhesive is shown in table 3.
TABLE 3 composition of bacteriostatic adhesive of example 3
The preparation method of the antibacterial adhesive comprises the following steps:
(1) Under the protection of nitrogen, adding naphthenic oil KN-6 into a reaction vessel, heating to 80 ℃, and stirring for 2.5h to obtain preheated naphthenic oil KN-6;
(2) Under the protection of nitrogen, adding the oligomeric lactic acid, the antibacterial polylactic acid, the antioxidant 1076 and the polyurethane elastomer (the mass ratio of PPDI to NDI is 5:1) into the preheated naphthenic oil KN-6 obtained in the step (1), heating to 120 ℃, mixing for 3 hours, discharging, and cooling to obtain the antibacterial adhesive.
The preparation method of the antibacterial adhesive tape based on the oligomeric lactic acid comprises the following steps:
(1) Coating a release agent on one surface of a polylactic acid film backing material by using a coating machine, wherein the coating amount is 2g/m2, the molecular weight of polylactic acid in the polylactic acid film is 15 ten thousand, and the film thickness of the polylactic acid film is 0.15mm;
(2) And heating the antibacterial adhesive to 105 ℃ for softening, coating the antibacterial adhesive on the other side of the backing material, wherein the coating amount is 2g/m2, and cooling and solidifying at room temperature to obtain the antibacterial adhesive tape based on the polylactic acid.
Ring-shaped primary adhesion test the test method was the same as in example 1. The annular primary adhesion was measured to be 7.56N;
180 ° peel force test method was the same as in example 1. 180℃peel force of 0.560kgf was measured;
Degradation by aging test the test method was the same as in example 1. The ML after 7 days of degradation was 73% and the ML after 30 days of degradation was 89%.
Antibacterial property test the test method was the same as in example 1. The antibacterial rate of S.aureus is 97.72%, the antibacterial rate of E.coli is 97.81%, and the antibacterial rate of C.albicans is 97.12% for the newly prepared adhesive tape. The antibacterial rate of S.aureus of the adhesive tape after 21 days aging is 94.79%, the antibacterial rate of E.coli is 93.88%, and the antibacterial rate of C.albicans is 92.95%.
Comparative example 1
The composition of the bacteriostatic adhesive is shown in table 4.
TABLE 4 composition of bacteriostatic adhesive of comparative example 1
The preparation method of the antibacterial adhesive comprises the following steps:
(1) Under the protection of nitrogen, adding naphthenic oil KN-6 into a reaction vessel, heating to 100 ℃, and stirring for 2 hours to obtain preheated naphthenic oil KN-6;
(2) Under the protection of nitrogen, adding the oligomeric lactic acid, the polylactic acid, the chitosan, the antioxidant 1076 and the polyurethane elastomer (the mass ratio of TDI to MDI is 2:1) into the preheated naphthenic oil KN-6 obtained in the step (1), heating to 100 ℃, mixing for 2 hours, discharging, and cooling to obtain the antibacterial adhesive.
The other steps are the same as in example 1.
Ring-shaped primary adhesion test the test method was the same as in example 1. The loop tack was measured to be 5.45N.
180 ° Peel force test method was the same as in example 1. 180℃peel force was measured to be 0.296kgf.
Degradation by aging test the test method was the same as in example 1. ML after 7 days of degradation was 82% and ML after 30 days of degradation was 94%.
Antibacterial property test the test method was the same as in example 1. The antibacterial rate of S.aureus is 84.61%, the antibacterial rate of E.coli is 83.93%, and the antibacterial rate of C.albicans is 83.51% for the newly prepared adhesive tape. The antibacterial rate of S.aureus of the adhesive tape after 21 days aging is 58.82%, the antibacterial rate of E.coli is 58.01%, and the antibacterial rate of C.albicans is 57.40%.
Results analysis the loop tack, 180 peel force of the bacteriostatic tape of comparative example 1 was reduced compared to example 1, mainly because the chitosan component was added to the adhesive system by physical blending, and the compatibility with other components was relatively poor, thereby affecting the adhesive properties. The antibacterial rate of the newly prepared adhesive tape is reduced, because the compatibility of chitosan and other components of the adhesive is poor, the chitosan is easy to separate and separate out, the chitosan is partially removed in the washing step of the sample pretreatment of the antibacterial performance test, so that the antibacterial rate is reduced, the adhesive system is more easy to separate out the chitosan after the adhesive tape is aged, and more chitosan is removed in the washing step of the sample pretreatment of the antibacterial performance test, so that the antibacterial rate of the adhesive tape is lower after 21 days of aging. The degradation rate of the tape of comparative example 1 was increased compared to example 1, because the chitosan was free from the adhesive system, resulting in a decrease in physical stability, which is manifested by an increase in degradation rate.
Comparative example 2
The composition of the bacteriostatic adhesive was not added with bacteriostatic polylactic acid, and the other steps were the same as in example 1.
Ring-shaped primary adhesion test the test method was the same as in example 1. The loop tack was measured to be 7.30N.
180 ° Peel force test method was the same as in example 1. 180℃peel force was measured to be 0.538kgf.
Degradation by aging test the test method was the same as in example 1. The ML after 7 days of degradation was found to be 78% and the ML after 30 days of degradation was found to be 90%.
Antibacterial property test the test method was the same as in example 1. The antibacterial rate of S.aureus is 24.51%, the antibacterial rate of E.coli is 23.07%, and the antibacterial rate of C.albicans is 25.16% for the newly prepared adhesive tape. The antibacterial rate of S.aureus of the adhesive tape after 21 days aging is 11.68%, the antibacterial rate of E.coli is 10.40%, and the antibacterial rate of C.albicans is 10.42%.
The results of analysis show that the annular initial adhesion and 180-degree peeling force of the antibacterial adhesive tape in comparative example 2 are not greatly changed compared with those of example 1, which indicates that the antibacterial polylactic acid has no obvious influence on the adhesive property. The antibacterial rate of the newly prepared adhesive tape is obviously reduced due to the lack of antibacterial polylactic acid serving as a main antibacterial active component, the weak antibacterial effect is derived from the antibacterial rate of the oligomeric lactic acid in the adhesive tape, and the antibacterial rate of the adhesive tape after 21 days of aging is reduced due to the fact that the oligomeric lactic acid is easy to decompose, and decomposition products are removed in a flushing step of antibacterial test pretreatment, so that the measured antibacterial rate is reduced.
Comparative example 3
The composition of the bacteriostatic adhesive was not supplemented with oligomeric lactic acid, and the procedure was otherwise as in example 1.
Ring-shaped primary adhesion test the test method was the same as in example 1. The loop tack was measured to be 3.93N.
180 ° Peel force test method was the same as in example 1. 180℃peel force was measured to be 0.144kgf.
Degradation by aging test the test method was the same as in example 1. The ML after 7 days of degradation was found to be 70% and the ML after 30 days of degradation was found to be 81%.
Antibacterial property test the test method was the same as in example 1. The antibacterial rate of S.aureus is 87.16%, the antibacterial rate of E.coli is 86.53%, and the antibacterial rate of C.albicans is 86.90% for the newly prepared adhesive tape. The antibacterial rate of S.aureus of the adhesive tape after 21 days aging is 75.72%, the antibacterial rate of E.coli is 76.08%, and the antibacterial rate of C.albicans is 75.99%.
Results analysis the loop tack, 180 ° peel force, of the bacteriostatic tape of comparative example 3 was significantly reduced compared to example 1 due to the lack of oligomeric lactic acid as a tackifier, which component acts to adjust the viscoelastic properties in the adhesive layer, with an imbalance in viscoelastic properties resulting in reduced adhesive properties. Compared with example 1, the antibacterial rate of the freshly prepared adhesive tape is reduced, because the oligomeric lactic acid can improve the dispersibility and the intersolubility of the antibacterial polylactic acid when the oligomeric lactic acid and the antibacterial polylactic acid are used cooperatively, and the antibacterial polylactic acid is not uniformly dispersed in the adhesive system when the oligomeric lactic acid is absent, so that the measured antibacterial rate is reduced. Because the dispersion of the antibacterial polylactic acid is not uniform enough, the antibacterial polylactic acid is partially removed in the flushing step of sample pretreatment of the antibacterial performance test for the aged adhesive tape, so that the measured antibacterial rate is reduced. The degradation rate of comparative example 3 was reduced compared to example 1, because the oligolactic acid is the most degradable component of the tape, and thus the degradation rate was reduced without the addition of oligolactic acid.
Comparative example 4
Polyurethane elastomer is not added to the composition of the bacteriostatic adhesive, and the other steps are the same as in example 1.
Ring-shaped primary adhesion test the test method was the same as in example 1. The loop tack was measured to be 3.50N.
180 ° Peel force test method was the same as in example 1. 180℃peel force was measured to be 0.133kgf.
Degradation by aging test the test method was the same as in example 1. The ML after 7 days of degradation was found to be 78% and the ML after 30 days of degradation was found to be 90%.
Antibacterial property test the test method was the same as in example 1. The antibacterial rate of S.aureus is 97.88%, the antibacterial rate of E.coli is 97.15%, and the antibacterial rate of C.albicans is 97.73% for the newly prepared adhesive tape. The antibacterial rate of S.aureus of the adhesive tape after 21 days aging is 94.36%, the antibacterial rate of E.coli is 94.55%, and the antibacterial rate of C.albicans is 93.05%.
Results analysis the loop tack, 180 peel force, of the bacteriostatic adhesive tape of comparative example 4 was significantly reduced as compared to example 1 due to the loss of polyurethane elastomer causing an imbalance in the viscoelastic ratio of the adhesive layer and a reduction in adhesive properties. Compared with the example 1, the antibacterial rate of the freshly prepared adhesive tape and the antibacterial rate of the aged adhesive tape are not changed significantly, which indicates that the influence of the polyurethane elastomer on the antibacterial activity is small. The degradation rate was also not significantly changed compared to example 1, indicating that the polyurethane elastomer had little effect on the degradability of the tape.
The tape performance test results of examples 1-3 are shown in Table 4, and the tape performance test results of comparative examples 1-4 are shown in Table 5.
TABLE 4 adhesive tape performance test results for examples 1-3
Table 5 results of the tape Performance test of comparative examples 1 to 4
And (3) performing chemical structure analysis on the polylactic acid, chitosan and antibacterial polylactic acid by nuclear magnetic resonance (1 H NMR), wherein the solvent is CDCl3.
The1 H NMR spectrum of polylactic acid is shown in FIG. 1, and the structural formula is as follows:
carboxyl hydrogen at position 1 is at 5.36ppm, hydroxyl hydrogen at position 6 is at 4.15ppm, hydrogen at positions 4 and 5 is at 5.15ppm, and hydrogen at positions 2 and 3 is at 1.57ppm.
The1 H NMR spectrum of chitosan is shown in FIG. 2, and the structural formula is as follows:
Hydrogen at position 1 was at 1.68ppm, hydrogen at position 2 was at 1.26ppm, hydrogen at position 3 was at 2.36ppm, hydrogen at position 4 was at 2.56ppm, and hydrogen at position 5 was at 5.76ppm.
The1 H NMR spectrum of antibacterial polylactic acid is shown in figure 3, the original hydroxyl hydrogen of polylactic acid at 4.15ppm disappears due to the crosslinking reaction between hydroxyl and CDI in polylactic acid, the original amino hydrogen of chitosan at 1.68ppm reduces and shifts to the right to 1.41ppm due to the crosslinking reaction between amino and PLA-CI in chitosan, so that chitosan is connected with polylactic acid through carbonyl groups, and a large amount of ester groups exist on the polylactic acid chain to have strong electron-withdrawing effect, so that the absorption peak of chitosan shifts to the right. From the figure, characteristic peaks belonging to polylactic acid were 5.25ppm and 1.22ppm, and characteristic peaks belonging to chitosan were 5.86ppm, 2.01ppm, 2.22ppm and 1.41ppm.
By comparing nuclear magnetic spectrograms of polylactic acid, chitosan and bacteriostatic polylactic acid, as shown in fig. 4, an absorption peak shown by an arrow at A is methyl hydrogen on a polylactic acid polymer chain, the absorption peak is found to shift rightwards by 0.35ppm, an absorption peak shown by an arrow at B is amino in chitosan, the number of amino hydrogen is reduced and shifts rightwards by 0.27ppm, and the chitosan and the polylactic acid are successfully connected, and are connected through carbonyl.