Compostable and degradable bio-based film and preparation method thereof

Abstract

The invention relates to the technical field of bio-based films, in particular to a compostable and degradable bio-based film and a preparation method thereof. The bio-based film prepared by the invention comprises the following components: polyurethane, wherein the polyurethane is obtained by reacting a polyol polymer, a chain extender and an isocyanate compound; the polysaccharide polymer is obtained through a polysaccharide molecule cross-linking reaction; the plant polysaccharide is selected from astragalus polysaccharide, Chinese yam polysaccharide, bletilla striata polysaccharide, pachymaran, soybean polysaccharide, glycyrrhiza polysaccharide, polygonatum polysaccharide, fucoidin or dandelion polysaccharide.

Description

Technical Field

[0001] The present disclosure relates to the technical field of bio-based films, and particularly to a compostable and degradable bio-based film and a preparation method thereof. Background Art

[0002] Since the 20th century, the environmental pollution problems caused by discarded polymer materials have received much attention. So far, an effective method proposed by researchers is to use biomass as raw materials to synthesize bio-based products with practical application value and clean and pollution-free through physical or chemical methods; bio-based polymers can be divided into natural bio-based polymer materials and synthetic bio-based polymer materials according to their sources. Among them, natural bio-based polymer materials widely exist in animals and plants in nature and can be directly obtained through certain extraction methods, such as chitosan, etc.; synthetic bio-based polymer materials include polylactic acid, polyurethane, etc.

[0003] As a common polymer resin on the market at present, polyurethane is widely used in agricultural production, civil life, construction, biological medicine and other fields by virtue of its good physical and mechanical properties, easily adjustable chemical structure and good biocompatibility. Summary of the Invention

[0004] The present disclosure provides a compostable and degradable bio-based film and a preparation method thereof to solve the deficiencies in the related art.

[0005] According to the first aspect of the embodiments of the present disclosure, a compostable and degradable bio-based film is provided. The bio-based film comprises the following components: (1) polyurethane; the polyurethane is obtained by the reaction of a polyol polymer, a chain extender and an isocyanate compound; (2) a polysaccharide polymer obtained by a polysaccharide molecule crosslinking reaction.

[0006] In one aspect of the present disclosure, the polyol polymer is selected from at least one of polypropylene glycol, polyethylene glycol, polytetrahydrofuran glycol, polycarbonate diol and polycaprolactone diol.

[0007] In one aspect of the present disclosure, the chain extender is selected from at least one of ethylene glycol, 1,4-butanediol, hydroquinone bis(2-hydroxyethyl) ether, trimethylolpropane, ethylenediamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 4,4'-methylenebis(3-chloro-2,6-diethylaniline) or diethyltoluenediamine.

[0008] In one aspect of the present disclosure, the isocyanate compound is selected from dimer acid diisocyanate.

[0009] In one aspect of the present disclosure, the dimer acid diisocyanate is selected from compounds having the following structural formula A: ; wherein, a, b, c, and d are each independently selected from integers of 3 - 12; preferably, a, b, c, and d are each independently selected from integers of 5 - 9.

[0010] In one aspect of the present disclosure, the dimer acid diisocyanate is selected from the following compound A-1: .

[0011] In the present disclosure, it is prepared using a bio-based material.

[0012] In one aspect of the present disclosure, the polysaccharide molecule is selected from modified plant polysaccharides, and the plant polysaccharides are selected from at least one of astragalus polysaccharide, yam polysaccharide, bletilla striata polysaccharide, poria cocos polysaccharide, soybean polysaccharide, licorice polysaccharide, polygonatum sibiricum polysaccharide, fucoidan, or dandelion polysaccharide.

[0013] In one aspect of the present disclosure, the modified plant polysaccharide is a plant polysaccharide modified by degradation and amination.

[0014] In one aspect of the present disclosure, the modified plant polysaccharide is prepared through the following steps: preparing a plant polysaccharide, adding the plant polysaccharide to a trifluoroacetic acid solution, and obtaining the degraded plant polysaccharide through heating, stirring, and dialysis; then reacting the degraded plant polysaccharide with 3-dimethylaminopropylamine to obtain the aminated modified plant polysaccharide.

[0015] According to the second aspect of the embodiments of the present disclosure, a method for preparing the aforementioned bio-based film is provided, and the method includes the following steps: Step 1: Prepare a dimer acid diisocyanate having the structure of Formula A; Step 2: Prepare a plant polysaccharide, which is selected from at least one of astragalus polysaccharide, yam polysaccharide, bletilla striata polysaccharide, poria cocos polysaccharide, soybean polysaccharide, licorice polysaccharide, polygonatum sibiricum polysaccharide, fucoidan, or dandelion polysaccharide; Step 3: Modify the plant polysaccharide to obtain a modified plant polysaccharide; Step 4: Mix a polyol polymer, the prepared dimer acid diisocyanate, and a catalyst, and then carry out polymerization; Step 5: Add a chain extender, the prepared modified plant polysaccharide, and a crosslinking agent to the system in Step 4, continue the reaction, and then add a terminator to obtain the material of Step 5; Step 6: Post-treat the material of Step 5 to obtain the bio-based film.

[0016] In one aspect of the present disclosure, the dimer acid diisocyanate having the structure of Formula A is compound A-1, and Step 1 includes the following steps: Step 1-1: Dimeric tall oil fatty acid is subjected to acyl chlorination reaction to obtain dimeric tall oil fatty acid acyl chloride; ; Step 1-2: The dimeric tall oil fatty acid acyl chloride is reacted with sodium azide to obtain compound A-1; 。

[0017] In one aspect of the present disclosure, Step 2 includes the following steps: Step 2-1: The plant raw material is crushed and sieved to obtain plant raw material powder; Step 2-2: The plant raw material powder is subjected to a defatting process to obtain defatted plant raw material; Step 2-3: The defatted plant raw material is subjected to hot water extraction to obtain crude plant polysaccharide; Step 2-4: The crude plant polysaccharide is subjected to a protein removal process and an alcohol precipitation process to obtain the plant polysaccharide.

[0018] In one aspect of the present disclosure, Step 3 includes the following steps: Step 3-1: The plant polysaccharide is added to trifluoroacetic acid solution, and after heating, stirring and dialysis, the degraded plant polysaccharide is obtained; Step 3-2: The degraded plant polysaccharide is reacted with 3-dimethylaminopropylamine to obtain amino-modified plant polysaccharide.

[0019] In one aspect of the present disclosure, the terminator is selected from at least one of n-butanol, cyclohexanol, ethanolamine, diethanolamine, N,N-diethylamine and N,N-dibutylamine.

[0020] In one aspect of the present disclosure, the crosslinking agent is selected from glutaraldehyde.

[0021] In one aspect of the present disclosure, the catalyst is selected from tin catalysts, titanium catalysts, germanium catalysts, antimony catalysts or metallocene catalysts.

[0022] The technical solutions provided by the embodiments of the present disclosure may include the following beneficial effects: As can be seen from the above embodiments, the present disclosure prepares a novel compostable polyurethane film, which combines polyurethane segments with a crosslinked plant polysaccharide structure and has a better degradation effect than using starch in the prior art; in addition, the antibacterial, antioxidant and other functions of the plant polysaccharide itself can still play a role, so it has broad prospects in the field of medical / cosmetic dressings.

[0023] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. Detailed Description

[0024] To make the objectives, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be clearly and completely described below in conjunction with the embodiments. Apparently, the described embodiments are some but not all of the embodiments of the present application. The embodiments described herein are illustrative in nature and are provided to provide a basic understanding of the present application. The embodiments of the present application should not be construed as a limitation on the present application.

[0025] For the sake of brevity, only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form a range not explicitly recited; and any lower limit can be combined with other lower limits to form a range not explicitly recited, and similarly any upper limit can be combined with any other upper limit to form a range not explicitly recited. In addition, each individually disclosed point or single numerical value itself can be used as a lower or upper limit and combined with any other point or single numerical value or with other lower or upper limits to form a range not explicitly recited.

[0026] In this document, the terms "comprising", "including" or any other variation thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or also elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of additional identical elements in the process, method, article or device comprising said element.

[0027] In the description herein, unless otherwise specified, "above" and "below" include the number itself.

[0028] Unless otherwise specified, the terms used in this disclosure have the well-known meanings commonly understood by those skilled in the art. Unless otherwise specified, the numerical values of the various parameters mentioned in this disclosure can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the embodiments of this disclosure).

[0029] The term "about" is used to describe and account for small variations. When used in connection with an event or circumstance, the term can refer to instances where the event or circumstance occurs precisely and instances where it occurs very nearly. For example, when used in connection with a numerical value, the term can refer to a range of variation of less than or equal to ±10% of that numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. Additionally, quantities, ratios, and other numerical values are sometimes presented in range format in this document. It should be understood that such range formats are for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly specified as range limits but also all individual numerical values or sub-ranges subsumed within that range as if each numerical value and sub-range were explicitly specified.

[0030] A list of items joined by the term "at least one of", "at least one in", "at least one kind in", or other similar terms can mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A can include a single component or multiple components. Item B can include a single component or multiple components. Item C can include a single component or multiple components.

[0031] The present disclosure provides a method for preparing a compostable and biodegradable biobased film, the method comprising the following steps: Step 1: Prepare a dimer diisocyanate (Compound A-1) having the following structure;

[0032] Step 2: Prepare a plant polysaccharide, the plant polysaccharide being selected from at least one of astragalus polysaccharide, yam polysaccharide, bletilla striata polysaccharide, poria cocos polysaccharide, soybean polysaccharide, licorice polysaccharide, polygonatum polysaccharide, fucoidan, or dandelion polysaccharide; Step 3: Chemically degrade and amino-modify the plant polysaccharide to obtain a modified plant polysaccharide; Step 4: Mix a polyol polymer, the prepared dimer diisocyanate, and a catalyst and then carry out polymerization; Step 5: Add a chain extender, the prepared modified plant polysaccharide, and a crosslinking agent to the system of Step 4, continue the reaction, and then add a terminator to obtain the material of Step 5; Step 6: Post-treat the material of Step 5 to obtain the biobased film.

[0033] In the present disclosure, in Step 1, dimerized tall oil fatty acid is first reacted with bis(trichloromethyl) carbonate to obtain dimerized tall oil fatty acid chloride:

[0034] Then, the dimerized tall oil fatty acid chloride is reacted with sodium azide to obtain Compound A-1:

[0035] The reaction of dimerized tall oil fatty acid chloride and sodium azide is a typical Curtius rearrangement reaction. First, the azide attacks the carbonyl carbon atom of the acyl chloride to undergo nucleophilic addition, and then the chloride ion is eliminated to form the nucleophilic substitution product acyl azide. The latter releases nitrogen gas under heating conditions and simultaneously obtains an isocyanate.

[0036] In the present disclosure, Step 1 specifically includes: adding a dimerized tall oil fatty acid - toluene solution (300 - 400 mL) with a molar concentration of 0.50 mol / L and the catalyst dimethylformamide into a reaction flask. Under the condition of a temperature of 70°C - 80°C and with stirring, a toluene solution (100 - 150 mL) containing 0.05 - 0.1 mol of bis(trichloromethyl) carbonate is added dropwise. After the addition, the reaction continues for 1 hour, and then it is cooled to room temperature. After filtration and rotary evaporation to remove toluene, dimerized tall oil fatty acid chloride is obtained. Then, sodium azide and 120 mL of deionized water are added to the reaction flask. At a temperature of 10°C and with stirring, a 200 mL acetone solution containing the previously obtained dimerized tall oil fatty acid chloride is added dropwise. After the addition, the reaction continues for 30 min, then 300 mL of n-hexane is added, and after stirring for 10 minutes, it is kept warm and allowed to stand for layering. The n-hexane layer is separated out, and then it is washed with cold water at 5°C and dried with anhydrous sodium sulfate to obtain a n-hexane solution of dimerized tall oil fatty acid azide. Then, 300 mL of n-hexane is added to the reaction flask. At a temperature of 65°C - 70°C and with stirring, the n-hexane solution of the previously obtained dimerized tall oil fatty acid azide is added dropwise. After the addition, the reaction continues for 30 minutes, and the n-hexane is evaporated to obtain Compound A-1.

[0037] In the present disclosure, step 2 is a process for preparing plant polysaccharides, wherein the plant polysaccharides are selected from at least one of astragalus polysaccharide, yam polysaccharide, bletilla striata polysaccharide, poria cocos polysaccharide, soybean polysaccharide, licorice polysaccharide, polygonatum sibiricum polysaccharide, fucoidan or dandelion polysaccharide. In the present disclosure, step 2 specifically includes: pulverizing the plant raw material and then sieving it to obtain a plant raw material powder; subjecting the plant raw material powder to a defatting process to obtain the defatted plant raw material; subjecting the defatted plant raw material to hot water extraction to obtain a crude plant polysaccharide; and subjecting the crude plant polysaccharide to a deproteinization process and an ethanol precipitation process to obtain the plant polysaccharide. In the present disclosure, the specific process of step 2 is not limited to the above, and the deproteinization process and the defatting process can also be carried out before or after the hot water extraction process; papain and other enzymes can also be added during the hot water extraction process for auxiliary enzymatic hydrolysis, or ultrasonic waves can be used for auxiliary extraction; for different plant raw materials, the steps of deproteinization and / or decolorization can also be omitted. The specific process of step 2 can be adaptively changed according to different plant raw materials.

[0038] In the present disclosure, when the plant polysaccharide is selected from yam polysaccharide, the preparation process of the yam polysaccharide includes: Step 7-1: Provide fresh yam as the plant raw material, peel and cut the fresh yam into pieces to obtain the cut yam; Step 7-2: Add the cut yam to water with a mass 8-16 times that of the yam, and obtain a yam homogenate after pulping; Step 7-3: Centrifuge the yam homogenate to obtain the centrifuged supernatant of the yam homogenate; Step 7-4: Filter the centrifuged supernatant of the yam homogenate to remove starch to obtain a filtrate; Step 7-5: Adjust the pH of the filtrate to 3.2-3.8, and then obtain a suspension through stirring; Step 7-6: Centrifuge the suspension; Step 7-7: Take the supernatant, adjust the pH to 6-8, and then perform ultrafiltration using an ultrafiltration membrane with a molecular cut-off of 5000 at 0.03-0.05 MPa; Step 7-8: Subject the retained part to vacuum freeze-drying to obtain yam polysaccharide.

[0039] In the present disclosure, when the plant polysaccharide is selected from polygonatum sibiricum polysaccharide, the preparation process of the polygonatum sibiricum polysaccharide includes: Step 8-1: Cut the dried polygonatum sibiricum into thin slices with a thickness of 0.2-1.0 mm; then put the thin slices into a pulverizer for pulverization, and the pulverization particle size is 0.05-0.1 mm; obtain polygonatum sibiricum powder; Step 8-2: Add the polygonatum sibiricum powder to petroleum ether with a mass 3-5 times that of the polygonatum sibiricum powder, and then reflux at a temperature of 60°C-70°C for 2 times, each reflux for 1-2 h, to complete the defatting process; Step 8-3: Recover petroleum ether. Add polygonatum sibiricum powder into water with a mass 15-20 times that of the polygonatum sibiricum, and perform ultrasonic-assisted extraction at 50°C - 60°C with a frequency of 30 - 35 kHz for two times, 20 minutes each time; Step 8-4: Filter and concentrate the extracted mixed system under reduced pressure to obtain the concentrated extract; Step 8-5: Add activated carbon to the concentrated extract for decolorization; Step 8-6: Separate the solid and liquid of the decolorized extract, then add absolute ethanol with a mass 4 times that of the extract for ethanol precipitation, and let it stand overnight; then centrifuge and dry to obtain polygonatum sibiricum polysaccharide.

[0040] In the present disclosure, when the plant polysaccharide is selected from bletilla striata polysaccharide, the preparation process of the bletilla striata polysaccharide includes: Step 9-1: Crush the bletilla striata rhizome into pieces and sieve through a 20-50 mesh sieve to obtain bletilla striata powder; Step 9-2: Place the bletilla striata powder in a Soxhlet extractor, add petroleum ether with a mass 3-5 times that of the bletilla striata powder, reflux for 4 h, and the reflux temperature is selected from 75°C - 85°C to complete the degreasing process; Step 9-3: Recover petroleum ether. Add the bletilla striata powder into an aqueous urea solution with a mass 10-15 times that of the bletilla striata, and the urea concentration in the aqueous urea solution is selected from 1-3 mol / L; perform water bath at 65°C - 75°C for 10-20 h; Step 9-4: Filter and concentrate the extracted mixed system under reduced pressure to obtain the concentrated extract; Step 9-5: Add 95% ethanol with a mass 3 times that of the extract to the concentrated extract for ethanol precipitation, and let it stand overnight; then wash and dry to obtain bletilla striata polysaccharide.

[0041] In the present disclosure, when the plant polysaccharide is selected from soybean polysaccharide, the preparation process of the soybean polysaccharide includes: Step 10-1: Crush the soybean residue into powder and sieve through a 50-80 mesh sieve to obtain soybean powder; Step 10-2: Add the soybean powder into water with a mass 4-8 times that of the soybean powder, heat at 80°C - 95°C for 2-3 h, and then filter to obtain the extract; Step 10-3: After centrifuging the extract, take the supernatant, adjust the pH value to 5.5-6.0, then add 95% ethanol with a mass 2 times that of the supernatant, centrifuge again, and take the precipitate; wash and dry the precipitate to obtain crude soybean polysaccharide; Step 10-4: Dissolve the crude soybean polysaccharide in an appropriate amount of water, and use the Sevag method to remove the free protein in the crude soybean polysaccharide: Mix the crude soybean polysaccharide solution and the Sevag reagent in a volume ratio of 4:1, shake for 10 min, place it in a separatory funnel, let it stand and separate into a supernatant, an intermediate protein layer, and a lower organic phase. Take the supernatant, and repeat the above operation 5 times to obtain the crude soybean polysaccharide supernatant; Step 10-5: Concentrate the crude soybean polysaccharide supernatant and place it in a dialysis bag, and dialyze it in running water for 48 h; Add 95% ethanol to the solution after dialysis treatment again, and after stirring, centrifuging, washing, and freeze-drying, the soybean polysaccharide is obtained.

[0042] In the present disclosure, Step 3 includes: adding the prepared plant polysaccharide to trifluoroacetic acid solution, and obtaining the degraded plant polysaccharide through heating, stirring, and dialysis; then subjecting the degraded plant polysaccharide to an amination reaction to obtain the aminated modified plant polysaccharide.

[0043] In the art, plant polysaccharides have characteristics such as large molecular weight, high degree of polymerization, complex structure, and high viscosity. In the present disclosure, by appropriately degrading macromolecular plant polysaccharides into polysaccharide fragments with a certain molecular weight, the utilization rate of polysaccharides can be improved, thereby further enhancing their binding ability with polyurethane fragments and compostable degradation ability. The present disclosure uses the acid degradation method in chemical degradation methods, which has simple operation, but oxidative degradation method, free radical degradation method, and enzymatic degradation method can also be used, and it is not limited thereto.

[0044] In the art, in the polymerization reaction of polyurethane, for the prepolymer formed by polyol / ether and isocyanate compounds, its end group has an isocyanate group; in the present disclosure, the plant polysaccharide is aminated and modified, and the amino group it has can bind to the isocyanate end group of the prepolymer. At the same time, the plant polysaccharide undergoes a cross-linking reaction under the action of acid and cross-linking agent; thereby forming an intertwined network of polyurethane chain segments and plant polysaccharide chain segments. The role of amination modification is to increase amino groups in the plant polysaccharide structure, which can not only bind to the isocyanate end group of the polyurethane prepolymer, but also form hydrogen bonds with the hydroxyl groups of polyol compounds in the polyurethane chain segments, further enhancing the mechanical properties of the polyurethane material.

[0045] In the present disclosure, the catalyst is selected from tin catalysts, titanium catalysts, germanium catalysts, antimony catalysts, or metallocene catalysts; the terminator is selected from n-butanol, cyclohexanol, ethanolamine, diethanolamine, N,N-diethylamine, or N,N-dibutylamine; the cross-linking agent is selected from glutaraldehyde; but it is not limited thereto.

[0046] In the present disclosure, the material obtained in step 5 is pellets, and the post-treatment process in step 6 includes: putting the pellets obtained in step 5 into a low-speed mixer, premixing for 30 minutes, then entering a crystallization dryer through a rotary valve for drying and crystallization treatment, and then performing an extrusion process through an extruder. The melt extruded by the extruder is extruded through a die head and cooled to obtain a film material.

[0047] In the present disclosure, polycarbonate diol (PCD-2000) and polycaprolactone diol (PCL-2000) are used as polyol polymers, and 1,4-butanediol (BDO) is used as a chain extender; however, it is not limited thereto.

[0048] The present disclosure will be further elaborated below in conjunction with examples. It should be understood that these examples are only used to illustrate the present disclosure and not to limit the scope of the present disclosure.

[0049] Example: Example 1: Example 1 includes the following steps: 1. Preparation of Compound A-1: Add a toluene solution of dimeric tall oil fatty acid with a molar concentration of 0.50 mol / L (400 mL) and a catalyst, dimethylformamide (0.35 mL), to a reaction flask. While maintaining the temperature at 80 °C and stirring, add dropwise a toluene solution (150 mL) containing 0.1 mol of bis(trichloromethyl) carbonate. After the addition is complete, continue the reaction for 1 hour, then cool to room temperature. After filtration and rotary evaporation to remove toluene, dimeric tall oil fatty acid chloride is obtained; then add 15 g of sodium azide and 120 mL of deionized water to the reaction flask. While maintaining the temperature at 10 °C and stirring, add dropwise a 200 mL acetone solution containing the previously obtained dimeric tall oil fatty acid chloride. After the addition is complete, continue the reaction for 30 min, then add 300 mL of n-hexane, stir for 10 minutes, keep warm and let it stand for layering. Separate the n-hexane layer, then wash it with cold water at 5 °C and dry it with anhydrous sodium sulfate to obtain a n-hexane solution of dimeric tall oil fatty acid azide. Then add 300 mL of n-hexane to the reaction flask. While maintaining the temperature at 70 °C and stirring, add dropwise the previously obtained n-hexane solution of dimeric tall oil fatty acid azide. After the addition is complete, continue the reaction for 30 minutes, and evaporate the n-hexane to obtain Compound A-1.

[0050] 2. Preparation of Modified Plant Polysaccharide (Soybean Polysaccharide): 70 g of soybean residue was pulverized and passed through a 50-mesh sieve to obtain soybean powder. The soybean powder was added to water with a mass six times that of the soybean powder and heated at 90 °C for 2.5 h, and then filtered to obtain an extract. After centrifuging the extract, the supernatant was taken, the pH value was adjusted to 5.5, and then 95% ethanol with a mass twice that of the supernatant was added. After centrifuging again (4500 r / min, 5 min), the precipitate was taken. The precipitate was washed (washed with water and acetone once each) and freeze-dried to obtain crude soybean polysaccharide. The crude soybean polysaccharide was dissolved in an appropriate amount of water to obtain a crude soybean polysaccharide solution. The Sevag method was used to remove free protein from the crude soybean polysaccharide: The crude soybean polysaccharide solution and Sevag reagent were mixed at a volume ratio of 4:1, shaken for 10 min, placed in a separatory funnel, and allowed to stand to be divided into a supernatant, an intermediate protein layer, and a lower organic phase. The supernatant was taken, and the above operation was repeated 5 times to obtain a crude soybean polysaccharide supernatant. The crude soybean polysaccharide supernatant was concentrated and placed in a dialysis bag (with a molecular weight cut-off of 2000 Da) and dialyzed in running water for 48 h. 95% ethanol with a mass twice that of the solution after dialysis treatment was added again, and after stirring, centrifuging, washing, and freeze-drying, soybean polysaccharide was obtained.

[0051] The prepared soybean polysaccharide was added to a trifluoroacetic acid solution (150 mL, 0.3 mol / L). After heating and stirring for 30 min, the temperature was lowered to room temperature, and then dialysis (with a molecular weight cut-off of 1000 Da) was carried out to obtain degraded soybean polysaccharide; The degraded soybean polysaccharide was added to 150 mL of isopropanol and stirred evenly; then argon was introduced, and 8 mL of 3-dimethylaminopropylamine was added, and stirring was continued evenly; 15 mL of a sodium hydroxide solution with a mass concentration of 10% was added dropwise to the flask. After sufficient reaction, the product was filtered, washed with absolute ethanol, filtered, and dried to obtain amino-modified soybean polysaccharide.

[0052] 3. Preparation of Polyurethane Granules: 150 parts by weight of polycarbonate diol (PCD-2000) and 120 parts by weight of polycaprolactone diol (PCL-2000) were melted at about 110 °C and then cooled to 60 °C, and then added to a reactor. The temperature was maintained at 60 °C, and then 15 parts by weight of compound A-1 and 2 parts by weight of the catalyst dimethyltin acid ester were added under rapid stirring, and nitrogen was introduced for protection. The reaction was carried out at a constant temperature for 2.5 h to obtain a prepolymer; then 10 parts by weight of amino-modified soybean polysaccharide, 2 parts by weight of maleic anhydride, 1 part by weight of glutaraldehyde, and 50 parts by weight of the chain extender 1,4-butanediol were added under stirring, and the reaction was continued for 2 h. Then 25 parts by weight of the terminator diethanolamine was added, and after washing and drying, the polyurethane granules of Example 1 were obtained.

[0053] 4. Preparation of polyurethane film: The obtained pellets are put into a low-speed mixer and premixed for 30 minutes, then enter a crystallization dryer through a rotary valve for drying and crystallization treatment, and then go through an extrusion process by an extruder. The melt extruded by the extruder is extruded through a die head and cooled to obtain the film material of Example 1.

[0054] Example 2: Example 2 includes the following steps: 1. Preparation of compound A-1: Add a solution of dimeric tall oil fatty acid - toluene (400 mL) with a molar concentration of 0.50 mol / L and a catalyst dimethylformamide (0.35 mL) into a reaction flask. While maintaining a stirring state at a temperature of 80 °C, dropwise add a toluene solution (150 mL) containing 0.1 mol of bis(trichloromethyl) carbonate. After the addition, continue the reaction for 1 hour, then cool to room temperature. After filtration and rotary evaporation to remove toluene, dimeric tall oil fatty acid chloride is obtained; then add 15 g of sodium azide and 120 mL of deionized water into the reaction flask. While stirring at a temperature of 10 °C, dropwise add a 200 mL acetone solution containing the previously obtained dimeric tall oil fatty acid chloride. After the addition, continue the reaction for 30 min, then add 300 mL of n-hexane, stir for 10 minutes, keep warm and let it stand for stratification, separate the n-hexane layer, then wash with cold water at 5 °C and dry with anhydrous sodium sulfate to obtain a n-hexane solution of dimeric tall oil fatty acid azide. Then add 300 mL of n-hexane into the reaction flask. While stirring at a temperature of 70 °C, dropwise add the previously obtained n-hexane solution of dimeric tall oil fatty acid azide. After the addition, continue the reaction for 30 minutes, evaporate n-hexane to obtain compound A-1.

[0055] 2. Preparation of modified plant polysaccharide (yam polysaccharide): Use fresh yam as the raw material. Peel and cut the fresh yam to obtain 60 g of cut yam. Add the cut yam into 600 mL of water, and after beating, obtain yam homogenate. Then centrifuge the yam homogenate at 2000 r / min for 5 min, then collect the supernatant and filter it. Then adjust the pH to about 3.5 with 0.5 mol / L hydrochloric acid, then stir for 30 min to obtain a suspension, and centrifuge the suspension at 3500 r / min for 5 min; then collect the supernatant and adjust the pH to about 7 with 0.1 mol / L hydrochloric acid and 0.1 mol / L NaOH, then under 0.03 - 0.05 MPa, use an ultrafiltration membrane with a molecular cut-off of 5000 for ultrafiltration; the retained part is vacuum freeze-dried to obtain yam polysaccharide.

[0056] Add the prepared yam polysaccharide into trifluoroacetic acid solution (200 mL, 0.3 mol / L). After heating and stirring for 30 min, cool to room temperature, and then obtain degraded yam polysaccharide through dialysis (cut-off molecular weight is 1000 Da); Add the degraded yam polysaccharide to 200 mL of isopropanol and stir evenly; then introduce argon and add 10 mL of 3-dimethylaminopropylamine, and continue to stir evenly; add 20 mL of a sodium hydroxide solution with a mass concentration of 10% dropwise to the flask. After sufficient reaction, filter the product, wash it with absolute ethanol, filter and dry it to obtain the amino-modified yam polysaccharide.

[0057] 3. Preparation of polyurethane pellets: Take 150 parts by weight of polycarbonate diol (PCD-2000) and 120 parts by weight of polycaprolactone diol (PCL-2000), melt them at about 110 °C, then cool to 60 °C, and then add them to a reactor. Keep the temperature at 60 °C, then add 15 parts by weight of compound A-1 and 2 parts by weight of the catalyst dimethyltin acid ester under rapid stirring, and introduce nitrogen for protection. Keep the temperature for reaction for 2.5 h to obtain a prepolymer; then add 10 parts by weight of the amino-modified yam polysaccharide, 2 parts by weight of maleic anhydride, 1 part by weight of glutaraldehyde and 50 parts by weight of the chain extender 1,4-butanediol under stirring, and continue to react for 2 h. Then add 25 parts by weight of the terminator diethanolamine, and after washing and drying, obtain the polyurethane pellets of Example 2.

[0058] 4. Preparation of polyurethane film: Put the obtained pellets into a low-speed mixer and premix for 30 minutes, then enter a crystallization dryer through a rotary valve for drying and crystallization treatment, and then carry out an extrusion process through an extruder. The melt extruded by the extruder is extruded through a die head and cooled to obtain the film material of Example 2.

[0059] Example 3: Example 3 includes the following steps: 1. Preparation of compound A-1: Add a solution of dimeric tall oil acid-toluene with a molar concentration of 0.50 mol / L (400 mL) and the catalyst dimethylformamide (0.35 mL) to a reaction flask. Under the condition of a temperature of 80 °C and continuous stirring, add dropwise a toluene solution (150 mL) containing 0.1 mol of bis(trichloromethyl) carbonate. After the addition is complete, continue to react for 1 hour, then cool to room temperature. After filtration and rotary evaporation to remove toluene, obtain dimeric tall oil acid chloride; then add 15 g of sodium azide and 120 mL of deionized water to the reaction flask. At a temperature of 10 °C and under stirring, add dropwise a 200 mL acetone solution containing the previously obtained dimeric tall oil acid chloride. After the addition is complete, continue to react for 30 min, then add 300 mL of n-hexane, stir for 10 minutes, keep the temperature and let it stand for stratification, separate the n-hexane layer, and then wash with cold water at 5 °C and dry with anhydrous sodium sulfate to obtain a n-hexane solution of dimeric tall oil acid azide. Then add 300 mL of n-hexane to the reaction flask. At a temperature of 70 °C and under stirring, add dropwise the previously obtained n-hexane solution of dimeric tall oil acid azide. After the addition is complete, continue to react for 30 minutes, and evaporate n-hexane to obtain compound A-1.

[0060] 2. Preparation of modified plant polysaccharide (Polygonatum sibiricum polysaccharide): Cut the dried Polygonatum sibiricum into thin slices with a thickness of 0.3 - 0.5 mm; then put the thin slices into a pulverizer for pulverization, and the pulverization particle size is 0.05 - 0.1 mm; 50 g of Polygonatum sibiricum powder is obtained; add the Polygonatum sibiricum powder to 250 mL of petroleum ether, and then reflux at 65 °C for 2 times, with each reflux for 1.5 h to complete the degreasing process; recover the petroleum ether, add the Polygonatum sibiricum powder to 1800 mL of water, and use ultrasonic wave with a frequency of 35 kHz for assisted extraction at 50 °C, extract twice, each time for 20 minutes; filter and concentrate the extracted mixed system under reduced pressure to 1 / 8 of the original volume to obtain the concentrated extract; add an appropriate amount of activated carbon to the concentrated extract for decolorization, then separate the solid and liquid of the decolorized extract, add 1000 mL of absolute ethanol for alcohol precipitation, and let it stand overnight; then through centrifugation and drying, Polygonatum sibiricum polysaccharide is obtained.

[0061] Add the prepared Polygonatum sibiricum polysaccharide to trifluoroacetic acid solution (200 mL, 0.3 mol / L), after heating and stirring for 30 min, cool down to room temperature, and then obtain the degraded Polygonatum sibiricum polysaccharide through dialysis (cut-off molecular weight is 1000 Da); Add the degraded Polygonatum sibiricum polysaccharide to 150 mL of isopropanol, stir evenly; then introduce argon gas, and add 8 mL of 3-dimethylaminopropylamine, continue to stir evenly; dropwise add 15 mL of sodium hydroxide solution with a mass concentration of 10% into the flask, after sufficient reaction, filter the product, wash it with absolute ethanol, filter and dry it to obtain the amino-modified Polygonatum sibiricum polysaccharide.

[0062] 3. Preparation of polyurethane pellets: Take 150 parts by weight of polycarbonate diol (PCD - 2000) and 120 parts by weight of polycaprolactone diol (PCL - 2000), melt them at about 110 °C, then cool to 60 °C, and then add them to a reactor, keep the temperature at 60 °C, then add 15 parts by weight of compound A - 1 and 2 parts by weight of catalyst dimethyltin acid ester under rapid stirring, and introduce nitrogen for protection, keep the temperature for reaction for 2.5 h to obtain a prepolymer; then add 10 parts by weight of amino-modified Polygonatum sibiricum polysaccharide, 2 parts by weight of maleic anhydride, 1 part by weight of glutaraldehyde and 50 parts by weight of chain extender 1,4-butanediol under stirring, continue to react for 2 h, then add 25 parts by weight of terminator diethanolamine, and obtain the polyurethane pellets of Example 3 after washing and drying.

[0063] 4. Preparation of polyurethane film: The obtained pellets were put into a low-speed mixer and premixed for 30 minutes, then entered a crystallization dryer through a rotary valve for drying and crystallization treatment, and then passed through an extruder for the extrusion process. The melt extruded from the extruder was extruded through a die head and cooled to obtain the film material of Example 3.

[0064] Example 4: Example 4 includes the following steps: 1. Preparation of compound A-1: A toluene solution (400 mL) of dimeric tall oil fatty acid with a molar concentration of 0.50 mol / L and a catalyst, dimethylformamide (0.35 mL), were added to a reaction flask. While maintaining the temperature at 80 °C and stirring, a toluene solution (150 mL) containing 0.1 mol of bis(trichloromethyl) carbonate was added dropwise. After the addition, the reaction continued for 1 hour, then cooled to room temperature. After filtration and rotary evaporation to remove toluene, dimeric tall oil fatty acid chloride was obtained. Then, 15 g of sodium azide and 120 mL of deionized water were added to the reaction flask. While maintaining the temperature at 10 °C and stirring, a 200 mL acetone solution containing the previously obtained dimeric tall oil fatty acid chloride was added dropwise. After the addition, the reaction continued for 30 min, then 300 mL of n-hexane was added, and after stirring for 10 minutes, it was kept warm and allowed to stand for stratification. The n-hexane layer was separated, then washed with cold water at 5 °C and dried with anhydrous sodium sulfate to obtain a n-hexane solution of dimeric tall oil fatty acid azide. Then, 300 mL of n-hexane was added to the reaction flask. While maintaining the temperature at 70 °C and stirring, the previously obtained n-hexane solution of dimeric tall oil fatty acid azide was added dropwise. After the addition, the reaction continued for 30 minutes, and n-hexane was evaporated to obtain compound A-1.

[0065] 2. Preparation of modified plant polysaccharide (Bletilla striata polysaccharide): The sliced tubers of Bletilla striata were crushed and passed through a 50-mesh sieve to obtain 60 g of Bletilla striata powder. The Bletilla striata powder was placed in a Soxhlet extractor, 400 mL of petroleum ether was added, and it was refluxed at 80 °C for 4 h to complete the degreasing process. The petroleum ether was recovered, and the Bletilla striata powder was added to 700 mL of a 2 mol / L urea aqueous solution, and it was bathed at 70 °C for 12 h. The extracted solution was filtered and concentrated under reduced pressure (concentrated to 1 / 4 of the original volume) to obtain a concentrated extract. 800 mL of 95% ethanol was added to the concentrated extract for alcohol precipitation, and it was left overnight to collect the precipitate. Then, after washing and drying, Bletilla striata polysaccharide was obtained.

[0066] The prepared Bletilla striata polysaccharide was added to a trifluoroacetic acid solution (200 mL, 0.3 mol / L). After heating and stirring for 30 min, it was cooled to room temperature, and then dialyzed (cut-off molecular weight of 1000 Da) to obtain degraded Bletilla striata polysaccharide. The degraded Bletilla striata polysaccharide was added to 150 mL of isopropanol and stirred evenly; then argon was introduced, and 8 mL of 3-dimethylaminopropylamine was added, and stirring was continued evenly; 15 mL of a sodium hydroxide solution with a mass concentration of 10% was added dropwise into the flask. After sufficient reaction, the product was filtered, washed with absolute ethanol, filtered, and dried to obtain the amino-modified Bletilla striata polysaccharide.

[0067] 3. Preparation of polyurethane pellets: Take 150 parts by weight of polycarbonate diol (PCD-2000) and 120 parts by weight of polycaprolactone diol (PCL-2000), melt them at about 110 °C, then cool to 60 °C, and then add them to a reactor, keeping the temperature at 60 °C. Then, 15 parts by weight of compound A-1 and 2 parts by weight of the catalyst dimethyltin acid ester were added under rapid stirring, and nitrogen was introduced for protection. The reaction was carried out at a constant temperature for 2.5 h to obtain a prepolymer; then, 10 parts by weight of the amino-modified Bletilla striata polysaccharide, 2 parts by weight of maleic anhydride, 1 part by weight of glutaraldehyde, and 50 parts by weight of the chain extender 1,4-butanediol were added under stirring, and the reaction was continued for 2 h. Then, 25 parts by weight of the terminator diethanolamine was added, and after washing and drying, the polyurethane pellets of Example 4 were obtained.

[0068] 4. Preparation of polyurethane film: The obtained pellets were put into a low-speed mixer and premixed for 30 minutes, then entered a crystallization dryer through a rotary valve for drying and crystallization treatment, and then were extruded through an extruder. The melt extruded by the extruder was extruded through a die head and cooled to obtain the film material of Example 4.

[0069] Example 5: Example 5 includes the following steps: 1. Preparation of compound A-1: A toluene solution (400 mL) of dimeric tall oil fatty acid with a molar concentration of 0.50 mol / L and the catalyst dimethylformamide (0.35 mL) were added to a reaction flask. Under the condition of a temperature of 80 °C and continuous stirring, a toluene solution (150 mL) containing 0.1 mol of bis(trichloromethyl) carbonate was added dropwise. After the addition, the reaction was continued for 1 hour, and then cooled to room temperature. After filtration, toluene was removed by rotary evaporation to obtain dimeric tall oil fatty acid chloride; then, 15 g of sodium azide and 120 mL of deionized water were added to the reaction flask. At a temperature of 10 °C and under stirring, a 200 mL acetone solution containing the previously obtained dimeric tall oil fatty acid chloride was added dropwise. After the addition, the reaction was continued for 30 min, then 300 mL of n-hexane was added, stirred for 10 minutes, and then kept warm and allowed to stand for stratification. The n-hexane layer was separated, and then washed with cold water at 5 °C and dried with anhydrous sodium sulfate to obtain a n-hexane solution of dimeric tall oil fatty acid azide. Then, 300 mL of n-hexane was added to the reaction flask. At a temperature of 70 °C and under stirring, the previously obtained n-hexane solution of dimeric tall oil fatty acid azide was added dropwise. After the addition, the reaction was continued for 30 minutes, and n-hexane was evaporated to obtain compound A-1.

[0070] 2. Preparation of modified plant polysaccharide (soybean polysaccharide): 70 g of soybean residue was crushed and sieved through a 50-mesh sieve to obtain soybean powder; the soybean powder was added to water with a mass six times that of the soybean powder, heated at 90 °C for 2.5 h, and then filtered to obtain an extract; after centrifuging the extract, the supernatant was taken, the pH value was adjusted to 5.5, and then 95% ethanol with a mass twice that of the supernatant was added. After centrifuging again (4500 r / min, 5 min), the precipitate was taken; the precipitate was washed (washed with water and acetone once each) and freeze-dried to obtain crude soybean polysaccharide; the crude soybean polysaccharide was dissolved in an appropriate amount of water to obtain a crude soybean polysaccharide solution, and the Sevag method was used to remove the free protein in the crude soybean polysaccharide: the crude soybean polysaccharide solution and Sevag reagent were mixed at a volume ratio of 4:1, shaken for 10 min, placed in a separatory funnel, and allowed to stand to be divided into a supernatant, an intermediate protein layer, and a lower organic phase. The supernatant was taken, and the above operation was repeated 5 times to obtain a crude soybean polysaccharide supernatant; the crude soybean polysaccharide supernatant was concentrated and placed in a dialysis bag (with a molecular weight cut-off of 2000 Da) and dialyzed in running water for 48 h; 95% ethanol with a mass twice that of the solution after dialysis treatment was added again, and after stirring, centrifuging, washing, and freeze-drying, soybean polysaccharide was obtained.

[0071] The prepared soybean polysaccharide was added to 150 mL of isopropanol and stirred evenly; then argon was introduced, and 8 mL of 3-dimethylaminopropylamine was added, and stirring was continued evenly; 15 mL of a 10% sodium hydroxide solution by mass was added dropwise to the flask. After sufficient reaction, the product was filtered, washed with absolute ethanol, filtered, and dried to obtain amino-modified soybean polysaccharide.

[0072] 3. Preparation of polyurethane pellets: 150 parts by weight of polycarbonate diol (PCD-2000) and 120 parts by weight of polycaprolactone diol (PCL-2000) were melted at about 110 °C and then cooled to 60 °C, and then added to a reactor, maintaining the temperature at 60 °C. Then, 15 parts by weight of compound A-1 and 2 parts by weight of the catalyst dimethyltin acid ester were added under rapid stirring, and nitrogen was introduced for protection. The reaction was carried out at a constant temperature for 2.5 h to obtain a prepolymer; then, 10 parts by weight of amino-modified soybean polysaccharide, 2 parts by weight of maleic anhydride, 1 part by weight of glutaraldehyde, and 50 parts by weight of the chain extender 1,4-butanediol were added under stirring, and the reaction was continued for 2 h. Then, 25 parts by weight of the terminator diethanolamine was added. After washing and drying, the polyurethane pellets of Example 5 were obtained.

[0073] 4. Preparation of polyurethane film: The obtained pellets are put into a low-speed mixer and premixed for 30 minutes, then enter a crystallization dryer through a rotary valve for drying and crystallization treatment, and then undergo an extrusion process through an extruder. The melt extruded from the extruder is extruded through a die head and cooled to obtain the film material of Example 5.

[0074] The difference between Example 5 and Example 1 is that the soy polysaccharide prepared in Example 5 does not undergo a degradation process.

[0075] Example 6: Example 6 includes the following steps: 1. Preparation of compound A-1: A toluene solution (400 mL) of dimeric tall oil fatty acid with a molar concentration of 0.50 mol / L and a catalyst, dimethylformamide (0.35 mL), are added to a reaction flask. While maintaining a stirring state at a temperature of 80 °C, a toluene solution (150 mL) containing 0.1 mol of bis(trichloromethyl) carbonate is added dropwise. After the addition, the reaction continues for 1 hour, and then it is cooled to room temperature. After filtration and rotary evaporation to remove toluene, dimeric tall oil fatty acid acyl chloride is obtained. Then, 15 g of sodium azide and 120 mL of deionized water are added to the reaction flask. While stirring at a temperature of 10 °C, a 200 mL acetone solution containing the previously obtained dimeric tall oil fatty acid acyl chloride is added dropwise. After the addition, the reaction continues for 30 min, then 300 mL of n-hexane is added, and after stirring for 10 minutes, it is kept warm and allowed to stand for layer separation. The n-hexane layer is separated, and then it is washed with cold water at 5 °C and dried with anhydrous sodium sulfate to obtain a n-hexane solution of dimeric tall oil fatty acid acyl azide. Then, 300 mL of n-hexane is added to the reaction flask. While stirring at a temperature of 70 °C, the previously obtained n-hexane solution of dimeric tall oil fatty acid acyl azide is added dropwise. After the addition, the reaction continues for 30 minutes, and the n-hexane is evaporated to obtain compound A-1.

[0076] 2. Preparation of modified plant polysaccharide (soybean polysaccharide): 70 g of soybean dregs were crushed and screened through a 50-mesh sieve to obtain soybean powder; the soybean powder was added to water with a mass 6 times that of the soybean powder, heated at 90 °C for 2.5 h, and then filtered to obtain an extract; after centrifuging the extract, the supernatant was taken, the pH value was adjusted to 5.5, and then 95% ethanol with a mass 2 times that of the supernatant was added. After centrifuging again (4500 r / min, 5 min), the precipitate was taken; the precipitate was washed (washed with water and acetone once each) and freeze-dried to obtain crude soybean polysaccharide; the crude soybean polysaccharide was dissolved in an appropriate amount of water to obtain a crude soybean polysaccharide solution, and the Sevag method was used to remove free protein in the crude soybean polysaccharide: the crude soybean polysaccharide solution and Sevag reagent were mixed at a volume ratio of 4:1, shaken for 10 min, placed in a separatory funnel, and left to stand to be divided into a supernatant, an intermediate protein layer, and a lower organic phase. The supernatant was taken, and the above operation was repeated 5 times to obtain a crude soybean polysaccharide supernatant; the crude soybean polysaccharide supernatant was concentrated and placed in a dialysis bag (with a molecular weight cut-off of 2000 Da) and dialyzed in running water for 48 h; 95% ethanol with a mass 2 times that of the solution after dialysis treatment was added again, and after stirring, centrifuging, washing, and freeze-drying, soybean polysaccharide was obtained.

[0077] The prepared soybean polysaccharide was added to a trifluoroacetic acid solution (150 mL, 0.3 mol / L). After heating and stirring for 30 min, the temperature was lowered to room temperature, and then it was dialyzed (with a molecular weight cut-off of 1000 Da) to obtain degraded soybean polysaccharide; 3. Preparation of polyurethane pellets: 150 parts by weight of polycarbonate diol (PCD-2000) and 120 parts by weight of polycaprolactone diol (PCL-2000) were melted at about 110 °C and then cooled to 60 °C. Then they were added to a reactor, and the temperature was maintained at 60 °C. Then, 15 parts by weight of compound A-1 and 2 parts by weight of the catalyst dimethyltin acid ester were added under the state of rapid stirring, and nitrogen was introduced for protection. The reaction was carried out at a constant temperature for 2.5 h to obtain a prepolymer; then, 10 parts by weight of degraded and modified soybean polysaccharide, 2 parts by weight of maleic anhydride, 1 part by weight of glutaraldehyde, and 50 parts by weight of the chain extender 1,4-butanediol were added under the stirring state, and the reaction continued for 2 h. Then, 25 parts by weight of the terminator diethanolamine was added, and after washing and drying, the polyurethane pellets of Example 1 were obtained.

[0078] 4. Preparation of polyurethane film: The obtained pellets were put into a low-speed mixer and premixed for 30 minutes, then entered a crystallization dryer through a rotary valve for drying and crystallization treatment, and then passed through an extruder for the extrusion process. The melt extruded by the extruder was extruded through a die head and cooled to obtain the film material of Example 6.

[0079] Example 6 is different from Example 1 in that the soy polysaccharide prepared in Example 6 did not undergo an amination modification process.

[0080] Example 7: Example 7 includes the following steps: 1. Preparation of Compound A-1: Add a toluene solution of dimeric tall oil fatty acid with a molar concentration of 0.50 mol / L (400 mL) and the catalyst dimethylformamide (0.35 mL) to a reaction flask. While maintaining a temperature of 80 °C and stirring, add dropwise a toluene solution (150 mL) containing 0.1 mol of bis(trichloromethyl) carbonate. After the addition, continue the reaction for 1 hour, then cool to room temperature. After filtration and rotary evaporation to remove toluene, dimeric tall oil fatty acid acyl chloride is obtained. Then, add 15 g of sodium azide and 120 mL of deionized water to the reaction flask. While maintaining a temperature of 10 °C and stirring, add dropwise a 200 mL acetone solution containing the previously obtained dimeric tall oil fatty acid acyl chloride. After the addition, continue the reaction for 30 min, then add 300 mL of n-hexane, stir for 10 minutes, keep warm and let it stand for stratification. Separate the n-hexane layer, then wash it with cold water at 5 °C and dry it with anhydrous sodium sulfate to obtain a n-hexane solution of dimeric tall oil fatty acid acyl azide. Then, add 300 mL of n-hexane to the reaction flask. While maintaining a temperature of 70 °C and stirring, add dropwise the previously obtained n-hexane solution of dimeric tall oil fatty acid acyl azide. After the addition, continue the reaction for 30 minutes, and evaporate the n-hexane to obtain Compound A-1.

[0081] 2. Preparation of modified plant polysaccharide (yam polysaccharide): Use fresh yam as the raw material. Peel and cut the fresh yam to obtain 60 g of cut yam. Add the cut yam to 600 mL of water, and after pulping, obtain yam homogenate. Then, centrifuge the yam homogenate at 2000 r / min for 5 min, then collect the supernatant and filter it. Then, adjust the pH to about 3.5 with 0.5 mol / L hydrochloric acid, then stir for 30 min to obtain a suspension. Centrifuge the suspension at 3500 r / min for 5 min. Then, collect the supernatant and adjust the pH to about 7 with 0.1 mol / L hydrochloric acid and 0.1 mol / L NaOH. Then, under 0.03 - 0.05 MPa, perform ultrafiltration using an ultrafiltration membrane with a molecular cut-off of 5000. The retained part is vacuum freeze-dried to obtain yam polysaccharide.

[0082] Add the prepared yam polysaccharide to 200 mL of isopropanol and stir evenly. Then, introduce argon gas and add 10 mL of 3-dimethylaminopropylamine, and continue to stir evenly. Add dropwise 20 mL of a 10% sodium hydroxide solution by mass concentration to the flask. After sufficient reaction, filter the product, wash it with absolute ethanol, filter and dry it to obtain aminated modified yam polysaccharide.

[0083] 3. Preparation of polyurethane pellets: Take 150 parts by weight of polycarbonate diol (PCD-2000) and 120 parts by weight of polycaprolactone diol (PCL-2000). After melting at about 110°C, cool to 60°C, then add them to a reactor, keep the temperature at 60°C, and then add 15 parts by weight of compound A-1 and 2 parts by weight of the catalyst dimethyltin acid ester under rapid stirring. Then introduce nitrogen for protection and carry out a heat preservation reaction for 2.5 h to obtain a prepolymer. Then add 10 parts by weight of amino-modified yam polysaccharide, 2 parts by weight of maleic anhydride, 1 part by weight of glutaraldehyde, and 50 parts by weight of the chain extender 1,4-butanediol under stirring, and continue the reaction for 2 h. Then add 25 parts by weight of the terminator diethanolamine. After washing and drying, the polyurethane pellets of Example 7 are obtained.

[0084] 4. Preparation of polyurethane film: Put the obtained pellets into a low-speed mixer and premix for 30 minutes, then enter a crystallization dryer through a rotary valve for drying and crystallization treatment, and then carry out an extrusion process through an extruder. The melt extruded by the extruder is extruded through a die head and cooled to obtain the film material of Example 7.

[0085] The difference between Example 7 and Example 1 is that the yam polysaccharide prepared in Example 7 did not undergo a degradation process.

[0086] Example 8: Example 8 includes the following steps: 1. Preparation of compound A-1: Add a toluene solution (400 mL) of dimeric tall oil fatty acid with a molar concentration of 0.50 mol / L and the catalyst dimethylformamide (0.35 mL) to a reaction flask. While maintaining the temperature at 80°C and stirring, dropwise add a toluene solution (150 mL) containing 0.1 mol of bis(trichloromethyl) carbonate. After the addition, continue the reaction for 1 hour, then cool to room temperature. After filtration and rotary evaporation to remove toluene, dimeric tall oil fatty acid chloride is obtained. Then add 15 g of sodium azide and 120 mL of deionized water to the reaction flask. While maintaining the temperature at 10°C and stirring, dropwise add a 200 mL acetone solution containing the previously obtained dimeric tall oil fatty acid chloride. After the addition, continue the reaction for 30 min, then add 300 mL of n-hexane, stir for 10 minutes, keep warm and let it stand for stratification, separate the n-hexane layer, then wash with cold water at 5°C and dry with anhydrous sodium sulfate to obtain a n-hexane solution of dimeric tall oil fatty acid azide. Then add 300 mL of n-hexane to the reaction flask. While maintaining the temperature at 70°C and stirring, dropwise add the previously obtained n-hexane solution of dimeric tall oil fatty acid azide. After the addition, continue the reaction for 30 minutes, and evaporate n-hexane to obtain compound A-1.

[0087] 2. Preparation of Modified Plant Polysaccharide (Chinese Yam Polysaccharide): Fresh Chinese yam is provided as the raw material. The fresh Chinese yam is peeled and cut into pieces, and a total of 60 g of cut Chinese yam is obtained. The cut Chinese yam is added to 600 mL of water, and after beating, a Chinese yam homogenate is obtained. Then, the Chinese yam homogenate is centrifuged at 2000 r / min for 5 min, and then the supernatant is collected and filtered. Then, 0.5 mol / L hydrochloric acid is used to adjust the pH to about 3.5, and then stirred for 30 min to obtain a suspension. The suspension is centrifuged at 3500 r / min for 5 min; then the supernatant is collected and 0.1 mol / L hydrochloric acid and 0.1 mol / L sodium hydroxide are used to adjust the pH to about 7, and then ultrafiltration is carried out using an ultrafiltration membrane with a molecular cut-off of 5000 under 0.03 - 0.05 MPa; the retained part is vacuum freeze-dried to obtain Chinese yam polysaccharide.

[0088] The prepared Chinese yam polysaccharide is added to a trifluoroacetic acid solution (200 mL, 0.3 mol / L). After heating and stirring for 30 min, it is cooled to room temperature, and then dialyzed (with a cut-off molecular weight of 1000 Da) to obtain degraded Chinese yam polysaccharide; 3. Preparation of Polyurethane Granules: Take 150 parts by weight of polycarbonate diol (PCD - 2000) and 120 parts by weight of polycaprolactone diol (PCL - 2000), melt them at about 110 °C, then cool to 60 °C, and then add them to a reactor, maintaining the temperature at 60 °C. Then, 15 parts by weight of compound A - 1 and 2 parts by weight of the catalyst dimethyltin acid ester are added under rapid stirring, and nitrogen is introduced for protection. The reaction is carried out at a constant temperature for 2.5 h to obtain a prepolymer; then, 10 parts by weight of degraded and modified Chinese yam polysaccharide, 2 parts by weight of maleic anhydride, 1 part by weight of glutaraldehyde, and 50 parts by weight of the chain extender 1,4 - butanediol are added under stirring, and the reaction continues for 2 h. Then, 25 parts by weight of the terminator diethanolamine is added, and after washing and drying, the polyurethane granules of Example 8 are obtained.

[0089] 4. Preparation of Polyurethane Film: The obtained granules are put into a low-speed mixing blender and premixed for 30 minutes, then enter a crystallization dryer through a rotary valve for drying and crystallization treatment, and then are extruded through an extruder. The melt extruded by the extruder is extruded through a die head and cooled to obtain the film material of Example 8.

[0090] The difference between Example 8 and Example 1 is that the Chinese yam polysaccharide prepared in Example 8 does not undergo the process of amination modification.

[0091] Example 9 includes the following steps: 1. Preparation of modified plant polysaccharide (soybean polysaccharide): Crush 70 g of soybean dregs and pass through a 50-mesh sieve to obtain soybean powder; add the soybean powder to water with a mass 6 times that of the soybean powder, heat at 90 °C for 2.5 h, and then filter to obtain an extract; after centrifuging the extract, take the supernatant, adjust the pH value to 5.5, then add 95% ethanol with a mass 2 times that of the supernatant, and after centrifuging again (4500 r / min, 5 min), take the precipitate; wash the precipitate (wash once with water and once with acetone), and then obtain crude soybean polysaccharide after freeze-drying; dissolve the crude soybean polysaccharide in an appropriate amount of water to obtain a crude soybean polysaccharide solution, and use the Sevag method to remove free protein in the crude soybean polysaccharide: mix the crude soybean polysaccharide solution and Sevag reagent in a volume ratio of 4:1, shake for 10 min, place in a separating funnel, and let it stand to be divided into supernatant, intermediate protein layer and lower organic phase, take the supernatant, and repeat the above operation 5 times to obtain a crude soybean polysaccharide supernatant; concentrate the crude soybean polysaccharide supernatant and place it in a dialysis bag (cut-off molecular weight is 2000 Da), and dialyze in running water for 48 h; add 95% ethanol with a mass 2 times that of the solution after dialysis treatment again, stir, centrifuge, wash and freeze-dry to obtain soybean polysaccharide.

[0092] Add the prepared soybean polysaccharide to trifluoroacetic acid solution (150 mL, 0.3 mol / L), heat and stir for 30 min, then cool to room temperature, and then obtain degraded soybean polysaccharide after dialysis (cut-off molecular weight is 1000 Da); Add the degraded soybean polysaccharide to 150 mL of isopropanol, stir evenly; then introduce argon gas, and add 8 mL of 3-dimethylaminopropylamine, and continue to stir evenly; drop 15 mL of sodium hydroxide solution with a mass concentration of 10% into the flask, filter the product after sufficient reaction, wash with absolute ethanol, filter and dry to obtain amino-modified soybean polysaccharide.

[0093] 2. Preparation of polyurethane pellets: Take 150 parts by weight of polycarbonate diol (PCD-2000) and 120 parts by weight of polycaprolactone diol (PCL-2000), melt at about 110 °C, then cool to 60 °C, and then add them to a reactor, keep the temperature at 60 °C, and then add 15 parts by weight of compound A-1 and 2 parts by weight of catalyst dimethyltin acid ester under rapid stirring, and introduce nitrogen for protection, keep the temperature and react for 2.5 h to obtain a prepolymer; then add 10 parts by weight of isophorone diisocyanate (IPDI), 2 parts by weight of maleic anhydride, 1 part by weight of glutaraldehyde and 50 parts by weight of chain extender 1,4-butanediol under stirring, continue to react for 2 h, and then add 25 parts by weight of terminator diethanolamine, and obtain the polyurethane pellets of Example 9 after washing and drying.

[0094] 4. Preparation of polyurethane film: The obtained pellets are put into a low-speed mixer and premixed for 30 minutes, then enter a crystallization dryer through a rotary valve for drying and crystallization treatment, and then undergo an extrusion process through an extruder. The melt extruded from the extruder is extruded through a die head and cooled to obtain the film material of Example 9.

[0095] Example 10: The steps of Example 10 are the same as those of Example 9, except that p-phenylene diisocyanate (PPDI) is used instead of isophorone diisocyanate (IPDI).

[0096] Example 11: 1. Preparation of Compound A-1: A toluene solution (400 mL) of dimeric tall oil fatty acid with a molar concentration of 0.50 mol / L and catalyst dimethylformamide (0.35 mL) are added to a reaction flask. While maintaining a stirring state at a temperature of 80 °C, a toluene solution (150 mL) containing 0.1 mol of bis(trichloromethyl) carbonate is added dropwise. After the addition, the reaction continues for 1 hour, then it is cooled to room temperature. After filtration and rotary evaporation to remove toluene, dimeric tall oil fatty acid chloride is obtained; then 15 g of sodium azide and 120 mL of deionized water are added to the reaction flask. While stirring at a temperature of 10 °C, a 200 mL acetone solution containing the previously obtained dimeric tall oil fatty acid chloride is added dropwise. After the addition, the reaction continues for 30 min, then 300 mL of n-hexane is added, and after stirring for 10 minutes, it is kept warm and allowed to stand for layering. The n-hexane layer is separated, then washed with cold water at 5 °C and dried with anhydrous sodium sulfate to obtain a n-hexane solution of dimeric tall oil fatty acid azide. Then 300 mL of n-hexane is added to the reaction flask. While stirring at a temperature of 70 °C, the previously obtained n-hexane solution of dimeric tall oil fatty acid azide is added dropwise. After the addition, the reaction continues for 30 minutes, and n-hexane is evaporated to obtain Compound A-1.

[0097] 2. Preparation of Modified Plant Polysaccharide (Soybean Polysaccharide): 70 g of soybean dregs were crushed and sieved through a 50-mesh sieve to obtain soybean powder; the soybean powder was added to water with a mass six times that of the soybean powder, heated at 90 °C for 2.5 h, and then filtered to obtain an extract; after centrifuging the extract, the supernatant was taken, the pH value was adjusted to 5.5, and then 95% ethanol with a mass twice that of the supernatant was added. After centrifuging again (4500 r / min, 5 min), the precipitate was taken; the precipitate was washed (washed with water and acetone once each) and freeze-dried to obtain crude soybean polysaccharide; the crude soybean polysaccharide was dissolved in an appropriate amount of water to obtain a crude soybean polysaccharide solution, and the Sevag method was used to remove the free protein in the crude soybean polysaccharide: the crude soybean polysaccharide solution and Sevag reagent were mixed in a volume ratio of 4:1, shaken for 10 min, placed in a separatory funnel, and allowed to stand to be divided into a supernatant, an intermediate protein layer, and a lower organic phase. The supernatant was taken, and the above operation was repeated 5 times to obtain a crude soybean polysaccharide supernatant; the crude soybean polysaccharide supernatant was concentrated and placed in a dialysis bag (with a molecular weight cut-off of 2000 Da) and dialyzed in running water for 48 h; 95% ethanol with a mass twice that of the solution after dialysis treatment was added again, and after stirring, centrifuging, washing, and freeze-drying, soybean polysaccharide was obtained.

[0098] The prepared soybean polysaccharide was added to trifluoroacetic acid solution (150 mL, 0.3 mol / L), heated and stirred for 30 min, cooled to room temperature, and then dialyzed (with a molecular weight cut-off of 1000 Da) to obtain degraded soybean polysaccharide; The degraded soybean polysaccharide was added to 100 mL of isopropanol, and then 50 mL of 0.5 mol / L NaOH solution was added. It was stirred at room temperature for 30 min, and then 2.5 g of chloroacetic acid was dissolved in 50 mL of isopropanol and added. The temperature was raised to 70 °C and stirred for 3 h, and then cooled to room temperature. The pH was adjusted to 7.4 with glacial acetic acid, and after dialysis, rotary evaporation concentration, and freeze-drying, carboxymethylated modified soybean polysaccharide was obtained.

[0099] 3. Preparation of Polyurethane Granules: 150 parts by weight of polycarbonate diol (PCD-2000) and 120 parts by weight of polycaprolactone diol (PCL-2000) were melted at about 110 °C, cooled to 60 °C, and then added to a reactor, maintaining the temperature at 60 °C. Then, 15 parts by weight of Compound A-1 and 2 parts by weight of the catalyst dimethyltin acid ester were added under rapid stirring, and nitrogen was introduced for protection. The reaction was carried out at a constant temperature for 2.5 h to obtain a prepolymer; then, 10 parts by weight of carboxymethylated modified soybean polysaccharide, 2 parts by weight of maleic anhydride, 1 part by weight of glutaraldehyde, and 50 parts by weight of the chain extender 1,4-butanediol were added under stirring, and the reaction continued for 2 h. Then, 25 parts by weight of the terminator diethanolamine was added, and after washing and drying, the polyurethane granules of Example 11 were obtained.

[0100] 4. Preparation of polyurethane film: The obtained pellets are put into a low-speed mixer and premixed for 30 minutes, then enter a crystallization dryer through a rotary valve for drying and crystallization treatment, and then go through an extrusion process by an extruder. The melt extruded by the extruder is extruded through a die head and cooled to obtain the film material of Example 11.

[0101] Example 12: The steps of Example 12 are basically the same as those of Example 1, except that the modified soy polysaccharide is replaced by chitosan.

[0102] Comparative Example 1: Comparative Example 1 includes the following steps: 1. Preparation of Compound A-1: A toluene solution (400 mL) of dimeric tall oil fatty acid with a molar concentration of 0.50 mol / L and a catalyst dimethylformamide (0.35 mL) are added to a reaction flask. While maintaining the temperature at 80 °C and stirring, a toluene solution (150 mL) containing 0.1 mol of bis(trichloromethyl) carbonate is added dropwise. After the addition, the reaction continues for 1 hour, and then it is cooled to room temperature. After filtration and rotary evaporation to remove toluene, dimeric tall oil fatty acid chloride is obtained; then 15 g of sodium azide and 120 mL of deionized water are added to the reaction flask. While maintaining the temperature at 10 °C and stirring, a 200 mL acetone solution containing the previously obtained dimeric tall oil fatty acid chloride is added dropwise. After the addition, the reaction continues for 30 min, then 300 mL of n-hexane is added, and after stirring for 10 minutes, it is kept warm and allowed to stand for stratification. The n-hexane layer is separated, and then it is washed with cold water at 5 °C and dried with anhydrous sodium sulfate to obtain a n-hexane solution of dimeric tall oil fatty acid azide. Then 300 mL of n-hexane is added to the reaction flask. While maintaining the temperature at 70 °C and stirring, the n-hexane solution of dimeric tall oil fatty acid azide obtained above is added dropwise. After the addition, the reaction continues for 30 minutes, and the n-hexane is evaporated to obtain Compound A-1.

[0103] 2. Preparation of modified starch: 50 g of amylose is added to 150 mL of isopropanol and stirred evenly; then argon is introduced, and 8 mL of 3-dimethylaminopropylamine is added and stirred evenly; 15 mL of a 10% sodium hydroxide solution by mass is added dropwise to the flask. After full reaction, the product is filtered, washed with absolute ethanol, filtered, and dried to obtain amino-modified starch.

[0104] 3. Preparation of polyurethane pellets: Take 150 parts by weight of polycarbonate diol (PCD-2000) and 120 parts by weight of polycaprolactone diol (PCL-2000). After melting at about 110°C, cool to 60°C, then add them to a reactor, keep the temperature at 60°C, and then add 15 parts by weight of compound A-1 and 2 parts by weight of the catalyst dimethyltin acid ester under rapid stirring, and introduce nitrogen for protection. Keep the temperature for reaction for 2.5 h to obtain a prepolymer; then add 10 parts by weight of amino-modified starch, 2 parts by weight of maleic anhydride, 1 part by weight of glutaraldehyde, and 50 parts by weight of chain extender 1,4-butanediol under stirring, and continue the reaction for 2 h. Then add 25 parts by weight of terminator diethanolamine, and after washing and drying, obtain the polyurethane pellets of Comparative Example 1.

[0105] 4. Preparation of polyurethane film: Put the obtained pellets into a low-speed mixer and premix for 30 minutes, then enter a crystallization dryer through a rotary valve for drying and crystallization treatment, and then carry out an extrusion process through an extruder. The melt extruded by the extruder is extruded through a die head and cooled to obtain the film material of Comparative Example 1.

[0106] Comparative Example 2: Comparative Example 2 includes the following steps: 1. Preparation of compound A-1: Add a toluene solution of dimeric tall oil fatty acid with a molar concentration of 0.50 mol / L (400 mL) and the catalyst dimethylformamide (0.35 mL) to a reaction flask. Under the condition of a temperature of 80°C and continuous stirring, dropwise add a toluene solution (150 mL) containing 0.1 mol of bis(trichloromethyl) carbonate. After the addition is complete, continue the reaction for 1 hour, then cool to room temperature. After filtration and rotary evaporation to remove toluene, obtain dimeric tall oil fatty acid acyl chloride; then add 15 g of sodium azide and 120 mL of deionized water to the reaction flask. Under the condition of a temperature of 10°C and stirring, dropwise add a 200 mL acetone solution containing the previously obtained dimeric tall oil fatty acid acyl chloride. After the addition is complete, continue the reaction for 30 min, then add 300 mL of n-hexane, stir for 10 minutes, keep the temperature and let it stand for layering, separate the n-hexane layer, then wash with cold water at 5°C and dry with anhydrous sodium sulfate to obtain a n-hexane solution of dimeric tall oil fatty acid acyl azide. Then add 300 mL of n-hexane to the reaction flask. Under the condition of a temperature of 70°C and stirring, dropwise add the previously obtained n-hexane solution of dimeric tall oil fatty acid acyl azide. After the addition is complete, continue the reaction for 30 minutes, and evaporate n-hexane to obtain compound A-1.

[0107] 2. Preparation of modified starch: Mix 3 mL of silane coupling agent KH560, 80 mL of acetone, and 20 mL of deionized water, add formic acid to adjust the pH value to 4.5, stir for 45 min, then add 50 g of amylose and mix for 1.5 h. Then neutralize with ammonia water and let it stand for 12 h, dry in vacuum and then break up to obtain epoxidized modified starch.

[0108] 3. Preparation of polyurethane pellets: Take 150 parts by weight of polycarbonate diol (PCD - 2000) and 120 parts by weight of polycaprolactone diol (PCL - 2000). After melting at about 110°C, cool to 60°C, then add them to a reactor, keep the temperature at 60°C, then add 15 parts by weight of compound A - 1 and 2 parts by weight of catalyst dimethyltin acid ester under rapid stirring, and introduce nitrogen for protection. Keep the temperature for reaction for 2.5 h to obtain a prepolymer; then add 10 parts by weight of epoxy - modified starch, 2 parts by weight of maleic anhydride, 1 part by weight of glutaraldehyde, and 50 parts by weight of chain extender 1,4 - butanediol under stirring, continue the reaction for 2 h, then add 25 parts by weight of terminator diethanolamine. After washing and drying, the polyurethane pellets of Comparative Example 2 are obtained.

[0109] 4. Preparation of polyurethane film: Put the obtained pellets into a low - speed mixing blender, premix for 30 minutes, then enter a crystallization dryer through a rotary valve for drying and crystallization treatment, and then carry out an extrusion process through an extruder. The melt extruded by the extruder is extruded through a die head and cooled to obtain the film material of Comparative Example 2.

[0110] Degradation ability test: Take samples with a specification of 50×50 mm from the products of Examples 1 - 11 and Comparative Examples 1 - 2, place them in a glass tank, fill with natural humus soil, control the temperature at 30°C, and let them stand naturally for biodegradation. Take them out for washing at 30 d, 60 d, and 90 d respectively, screen them with a 3 - mm sieve, take the materials on the sieve for drying, and calculate the degradation rate = (difference between the initial mass and the mass after degradation)×100% / initial mass. The specific test data are shown in Table 1.

[0111] Table 1:

[0112] Comparing Examples 1 - 4 and Examples 5 - 8, it can be seen that both degradation modification and amination modification can improve the compost biodegradability of the samples. Because the polysaccharide structure is further miniaturized after degradation, the structure cross - linked therefrom is more easily degraded under natural conditions; and amination modification can endow the polysaccharide structure with amino groups, which can combine with the isocyanate groups at the ends of the prepolymer. Thus, during the degradation process, due to the decomposition of the polysaccharide structure, the polyurethane chain segments also break, further accelerating the degradation process. Comparing Examples 9 - 11, it can be seen that the bio - based isocyanate compounds prepared in the present disclosure have better biodegradability compared to commonly used isocyanate materials; comparing Example 12 and Comparative Examples 1 - 2, it can be seen that the materials prepared in the present application also have better biodegradability compared to starch and chitosan used in the prior art.

[0113] Tensile strength test: Samples were taken from the products of Examples 1-11 and Comparative Examples 1-2, and a tensile test was carried out with reference to the GB / T528-2009 standard. The experimental results are shown in Table 2.

[0114] Table 2:

[0115] By comparing Examples 1-4, Examples 5-8 and Example 11, it can be seen that both the degradation modification and the amination modification can improve the tensile strength of the samples. This is because the amination modification can endow the polysaccharide structure with amino groups, which can combine with the isocyanate groups at the end of the prepolymer, and the amino groups can also form hydrogen bonds with the hydroxyl groups on the polyurethane segments, thereby further improving the intermolecular binding strength, so that the products of the present disclosure have better tensile properties; while the degradation modification can reduce the influence of the large space of the polysaccharide structure on the mechanical properties of the polyurethane material; the degradation modification can decompose the polysaccharide structure with a large molecular mass into a polysaccharide structure with a small molecular mass, which is conducive to improving its binding ability with the polyurethane segments. In Comparative Examples 1-2, starch was used, and its large structure affected the mechanical properties of the material.

[0116] Antibacterial ability test: The antibacterial properties of Examples 1-4, Example 12 and Comparative Examples 1-2 were tested by the shaking flask method according to QB / T2591—2003. Preparation of bacterial suspension: Take 50 μL of the original Staphylococcus aureus solution from the low-temperature storage room (-70 °C) and add it to 15 mL of sterilized Luria-Bertani (LB) culture medium, and place it in a shaker at 37 °C and 200 r / min for 6 h to obtain a bacterial suspension. After taking it out, it was diluted to 5.0×105-10.0×105 CFU / mL with sterile ultrapure water. Shaking flask method: The products of Examples 1-4, Example 12 and Comparative Examples 1-2 (1 cm×1 cm, treated by ultraviolet sterilization) were put into a 50 mL sterile triangular flask containing 10 mL of the diluted bacterial suspension, sealed with a sealing film, and shaken in a shaker at 37 °C and 200 r / min for 2 h. LB solid medium plate inoculation: Pour the molten LB solid medium into a sterile polypropylene plate, cure it under ultraviolet light for 30 min, take 100 μL of the bacterial suspension from the sample flask and evenly coat it on the solid medium with a spreading rod, seal it and invert it in a constant temperature incubator at 37 °C for incubation for 24 h, and count the number of bacterial colonies. The antibacterial durability of the samples was tested by the water extraction method. After the sample film (2 cm×2 cm) was washed for different times with water, the antibacterial effect was tested by the shaking flask method again.

[0117] The calculation formula for the antibacterial rate (R) is: R = (B−C) / B×100% (where: B is the average number of bacteria recovered per plate after 24 h of the blank sample; C is the average number of bacteria recovered per plate after 24 h of the sample plate); the results are shown in Table 3.

[0118] Table 3:

[0119] As can be seen, Examples 1-4, especially Example 4 using Bletilla striata polysaccharide, have significantly superior antibacterial ability compared to Example 12 using chitosan; while the comparative example using starch has no obvious antibacterial ability.

[0120] Those skilled in the art will readily conceive of other embodiments of the present disclosure upon considering the specification and practicing the disclosure herein. The present disclosure is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include known common general knowledge or conventional technical means in the technical field not disclosed by the present disclosure.

Claims

1. A compostable and biodegradable bio-based film, characterized in that, The bio-based film contains the following components: (1) Polyurethane; The polyurethane is obtained by the reaction of a polyol polymer, a chain extender and an isocyanate compound; (2) A polysaccharide polymer obtained by a polysaccharide molecule cross-linking reaction Among them, the isocyanate compound is selected from dimer acid diisocyanate, and the dimer acid diisocyanate is selected from compounds having the following structural formula A: , where a, b, c, and d are each independently selected from integers from 3 to 12; The polysaccharide molecule is selected from modified plant polysaccharides, and the plant polysaccharides are selected from at least one of astragalus polysaccharide, yam polysaccharide, bletilla striata polysaccharide, poria cocos polysaccharide, soybean polysaccharide, licorice polysaccharide, polygonatum sibiricum polysaccharide, fucoidan or dandelion polysaccharide.

2. The biobased film according to claim 1, wherein, The polyol polymer is selected from at least one of polypropylene glycol, polyethylene glycol, polytetrahydrofuran ether glycol, polycarbonate glycol and polycaprolactone glycol; the chain extender is selected from at least one of ethylene glycol, 1,4-butanediol, hydroquinone dihydroxyethyl ether, trimethylolpropane, ethylenediamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 4,4'-methylenebis(3-chloro-2,6-diethylaniline) or diethyltoluenediamine.

3. The bio-based film according to claim 1, wherein The dimer acid diisocyanate is selected from the following compound A-1: .

4. A method for preparing the biobased film according to any one of claims 1-3, characterized in that, The method includes the following steps: Step 1: Prepare a dimer diisocyanate having a structure of formula A; Step 2: Prepare a plant polysaccharide, which is selected from at least one of astragalus polysaccharide, yam polysaccharide, bletilla striata polysaccharide, poria cocos polysaccharide, soybean polysaccharide, licorice polysaccharide, polygonatum sibiricum polysaccharide, fucoidan or dandelion polysaccharide; Step 3: Modify the plant polysaccharide to obtain a modified plant polysaccharide; Step 4: Mix the polyol polymer, the prepared dimer diisocyanate and a catalyst, and then carry out polymerization; Step 5: Add a chain extender, the prepared modified plant polysaccharide and a cross-linking agent to the system in Step 4, continue the reaction, and then add a terminator to obtain the material of Step 5; Step 6: Post-treat the material of Step 5 to obtain the bio-based film.

5. The method according to claim 4, characterized in that, Step 1 includes the following steps: Step 1-1: Obtain dimer tall oil acid chloride through the acyl chlorination reaction of dimer tall oil acid; ; Step 1-2: React the dimerized tall oil acid acyl chloride with sodium azide to obtain compound A-1; .

6. The method according to claim 4, wherein Step 2 includes the following steps: Step 2-1: Crush the plant raw material and then screen it to obtain a plant raw material powder; Step 2-2: Subject the plant raw material powder to a degreasing process to obtain a degreased plant raw material; Step 2-3: Subject the degreased plant raw material to hot water extraction to obtain a crude plant polysaccharide; Step 2-4: Subject the crude plant polysaccharide to a deproteinization process and an alcohol precipitation process to obtain the plant polysaccharide.

7. The method according to claim 4, wherein Step 3 includes the following steps: Step 3-1: Add the plant polysaccharide to a trifluoroacetic acid solution, and obtain a degraded plant polysaccharide through heating, stirring and dialysis; Step 3-2: React the degraded plant polysaccharide with 3-dimethylaminopropylamine to obtain an amino-modified plant polysaccharide.

8. The method according to claim 4, characterized in that, The terminator is selected from at least one of n-butanol, cyclohexanol, ethanolamine, diethanolamine, N,N-diethylamine and N,N-dibutylamine, and the cross-linking agent is selected from glutaraldehyde; the catalyst is selected from tin catalysts, titanium catalysts, germanium catalysts, antimony catalysts or metallocene catalysts.

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