Degradable antibacterial wood-plastic composite film and preparation method thereof

Abstract

The invention provides a degradable antibacterial wood-plastic composite film, which comprises the following components: 50-100 parts of PBAT (poly (butylene adipate-co-terephthalate)); 20 to 60 parts of PLA (polylactic acid); 5-20 parts of modified cellulose; 0.5 to 10 parts of six-functional group polyurethane acrylate; 0.1 to 2.0 parts of a chain extender; 0.1 to 0.8 part of a plasticizer; 0.1 to 1 part of a lubricant; the invention provides a method for preparing a novel material by using wood residues by taking the residues obtained after taxol is extracted from taxus chinensis as an example, and the recycling of recyclable wood wastes is promoted. The problem of poor antibacterial ability of a common plastic film is solved; and wood-plastic compounding does not affect the degradation performance of the degradable plastic base material, and white pollution can be effectively reduced.

Description

Technical Field

[0001] The invention relates to the field of composite films, and in particular to a degradable antibacterial wood-plastic composite film and a preparation method thereof. Background Art

[0002] Traditional plastic films are non-degradable and pollute the environment. Plastic films have poor antibacterial properties, which limits their scope of use. The residues left after the extraction of some medicinal plant ingredients are randomly composted or landfilled, and their potential value is not fully explored.

[0003] In order to actively respond to the national call for "carbon peak and carbon neutrality" and reduce white pollution, while health and antibacterial products are increasingly attracting people's attention, it is urgent to develop environmentally friendly materials with antibacterial effects from the perspective of materials. In recent years, wood-plastic composites have attracted much attention and relevant research in domestic and foreign academic and industry circles. It is defined as the use of plastic polymers and plant fibers such as wood powder, rice husks, and bamboo powder to mix into new wood materials, which are widely used in decorative panels, packaging and other fields. Among many polymer materials, polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT) have attracted widespread attention due to their good biodegradability, but the use of these two materials alone has certain limitations. In the past few years, researchers have done a lot of research on PLA and PBAT and their blends, but the cost issue has always been an important factor that plagues their market application. In this regard, adding appropriate fillers during blending can reduce the amount of PLA and PBAT, thereby reducing costs. Among a series of fillers, plant fillers have become the preferred fillers for blending and modification of degradable plastics because they are derived from natural products and have degradability.

[0004] The yew is an ancient tree species with medical value. The ancient Chinese medical classic "Compendium of Materia Medica" has made detailed records of the yew, believing that the yew can regulate menstruation and promote diuresis, and has special therapeutic effects on kidney disease, gastrointestinal disease, diabetes, typhoid fever, and cholera. It is often used for treatment, health preservation, and physical fitness. The most important thing is that scientists have discovered a substance called paclitaxel in the yew, which is extracted and made into medicine, becoming one of the drugs for treating metastatic ovarian cancer and breast cancer. Therefore, yew is widely used for drug extraction. However, the artificial cultivation of yew is not only time-consuming and labor-intensive, but also ecologically unfriendly. The content of paclitaxel in the plant body is very small, and the content of ordinary varieties is about 0.01%. It takes 6 yew trees with an age of 60-100 years to cure an ovarian cancer patient. Therefore, after the extraction of paclitaxel, a very large amount of plant residues are left. The current common treatment method for this type of plant residues is direct composting. The potential value of the residues has not been fully utilized, which has caused a waste of resources to a certain extent. We found that there are a lot of plant fibers in the yew residue after paclitaxel extraction, which can be used as high-quality filling materials for biodegradable polymers. If the cellulose in the discarded yew residue can be extracted and blended into the PLA / PBAT composite material to obtain a new bio-based degradable material, it will not only not reduce the degradable properties of the material itself, but also reduce costs and promote the chemical recycling process of recyclable waste, which has strong practical significance. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention proposes a degradable antibacterial wood-plastic composite film and a preparation method. Taking the residue after paclitaxel extraction from yew as an example, the present invention proposes a method of using wood residues to prepare new materials, which promotes the recycling of recyclable wood waste. The problem of poor antibacterial ability of ordinary plastic films is solved; wood-plastic composite does not affect the degradation performance of degradable plastic substrates, and can effectively reduce white pollution.

[0006] To achieve the above object, the present invention provides the following technical solutions: A degradable antibacterial wood-plastic composite film comprises the following components: 50-100 parts of PBAT; 20-60 parts of PLA; 5-20 parts of modified cellulose; 0.5-10 parts of hexafunctional polyurethane acrylate; 0.1-2.0 parts of chain extender; 0.1-0.8 parts of plasticizer; 0.1-1 parts of lubricant; 0.1-0.3 parts of antioxidant, 0.1-0.3 parts of light stabilizer and 1.0-4.0 parts of talc.

[0007] As a further solution of the present invention, it includes the following components: 70 parts of PBAT; 30 parts of PLA; 5 parts of modified cellulose; 0.5 parts of hexafunctional polyurethane acrylate, 0.5 parts of chain extender; 0.3 parts of plasticizer; 0.1 parts of lubricant; 0.1 parts of antioxidant, 0.1 parts of light stabilizer, and 2.0 parts of talc.

[0008] As a further solution of the present invention, the modified cellulose is obtained by mixing and stirring cellulose extracted from Taxus chinensis with 2,2,6,6-tetramethylpiperidine-1-oxyl and nano-zinc solution, ultrasonically dispersing the mixture, filtering and drying the mixture, wherein the ratio of cellulose extracted from Taxus chinensis, 2,2,6,6-tetramethylpiperidine-1-oxyl and nano-zinc solution is 100:(1-10):(1-5), preferably 100:2:1.

[0009] As a further solution of the present invention, the chain extender is copolymerized by styrene, glyceryl methacrylate and carbodiimide, wherein the ratio of styrene, glyceryl methacrylate and carbodiimide is 1:(0.5-1):(0.1-1), preferably 1:0.5:0.5.

[0010] As a further solution of the present invention, the hexafunctional polyurethane acrylate is prepared by addition polymerization of diisocyanate, polyoxypropylene glycol and pentaerythritol triacrylate, preferably in a 1:1:1 ratio.

[0011] The present invention also provides a method for preparing a degradable antibacterial wood-plastic composite film, comprising the following steps: Step S1: extracting cellulose from the residue after paclitaxel is extracted from yew; Step S2: Modification of cellulose: cellulose extracted from Taxus chinensis is mixed with 2,2,6,6-tetramethylpiperidin-1-oxyl and nano zinc solution, and then ultrasonically dispersed, filtered and dried to obtain the obtained product; Step S3: blending: 50-100 parts of PBAT, 20-60 parts of PLA, 5-20 parts of modified cellulose, 0.5-10 parts of hexafunctional polyurethane acrylate, 0.1-2.0 parts of chain extender, 0.1-0.8 parts of plasticizer, 0.1-1 parts of lubricant, 0.1-0.3 parts of antioxidant, 0.1-0.3 parts of light stabilizer, and 1.0-4.0 parts of talc are mixed in proportion and then put into an internal mixer for blending to obtain a composite material; Step S4: putting the obtained composite material into a flat vulcanizer, setting the upper and lower plates to 190° C. and 200° C. respectively, hot pressing for 3 minutes, and taking out the obtained film after cooling to obtain a biodegradable antibacterial wood-plastic composite film.

[0012] As a further scheme of the present invention, the step S1 specifically includes: raw material pretreatment: first, the yew residue is processed into powder with an ultrafine grinder, and the particle size is 60 mesh to 300 mesh, and then placed in a blast drying oven, dried at 85°C, and dried for 20h to 24h to obtain yew dry powder; ethanol treatment: the yew dry powder is mixed with 95% industrial ethanol, boiled and refluxed for 4 hours, and then washed and dried; alkali treatment: the powder after ethanol treatment is mixed with concentrated NaOH, and stirred at 80°C for 2h; pH adjustment: H2SO4 is added to adjust the pH to neutral, and washed; centrifugation and drying: the system is placed in a centrifuge for centrifugal separation, and the solid part is dried to obtain a cellulose product.

[0013] As a further solution of the present invention, the step S3 specifically includes: placing the modified cellulose, PLA and PBAT in a vacuum oven at 60°C and drying for 24 hours; adding PBAT, PLA, modified cellulose, hexafunctional polyurethane acrylate, chain extender, plasticizer, lubricant and antioxidant in a high-speed mixer and mixing for 5 minutes, and then placing in an internal mixer, setting the first, second and third zones to 190°C, the speed to 90R / min, and the blending time to 10 minutes to obtain a degradable antibacterial wood-plastic composite material.

[0014] As a further embodiment of the present invention, the structure of the chain extender is .

[0015] As a further embodiment of the present invention, the plasticizer is tributyl citrate, the lubricant is vinyl bisstearamide, the antioxidant is Irganox 1010, and the light stabilizer is BASF 944.

[0016] The present invention has the following beneficial effects: The present invention proposes a method of preparing new materials using wood residues, which promotes the recycling of recyclable wood waste and solves the problem of poor antibacterial ability of ordinary plastic films. The wood-plastic composite does not affect the degradation performance of the degradable plastic substrate and can effectively reduce white pollution. DETAILED DESCRIPTION Example 1

[0017] A degradable antibacterial wood-plastic composite film, comprising the following components: 50-100 parts of PBAT; 20-60 parts of PLA; 5-20 parts of modified cellulose; 0.5-10 parts of hexafunctional polyurethane acrylate; 0.1-2.0 parts of chain extender; 0.1-0.8 parts of plasticizer; 0.1-1 parts of lubricant; 0.1-0.3 parts of antioxidant, 0.1-0.3 parts of light stabilizer, and 1.0-4.0 parts of talc Preferably, the composition includes the following ingredients: 70 parts of PBAT; 30 parts of PLA; 5 parts of modified cellulose; 0.5 parts of hexafunctional polyurethane acrylate, 0.5 parts of chain extender; 0.3 parts of plasticizer; 0.1 parts of lubricant; 0.1 parts of antioxidant, 0.1 parts of light stabilizer, and 2.0 parts of talc.

[0018] More preferably, the modified cellulose is obtained by mixing cellulose extracted from Taxus chinensis with 2,2,6,6-tetramethylpiperidine-1-oxyl and nano-zinc solution, stirring, ultrasonically dispersing, filtering and drying, wherein the ratio of cellulose extracted from Taxus chinensis, 2,2,6,6-tetramethylpiperidine-1-oxyl and nano-zinc solution is 100:(1-10):(1-5), preferably 100:2:1; Furthermore, the chain extender is copolymerized with styrene, methacrylate glycerol, and carbodiimide, wherein the ratio of styrene, methacrylate glycerol, and carbodiimide is 1: (0.5-1): (0.1-1), preferably 1: 0.5: 0.5; The hexafunctional polyurethane acrylate is prepared by addition polymerization of diisocyanate, polyoxypropylene glycol and pentaerythritol triacrylate, preferably in a 1:1:1 ratio. Example 2

[0019] A method for preparing a degradable antibacterial wood-plastic composite film comprises the following steps: Step S1: extracting cellulose from the residue after paclitaxel is extracted from yew; Step S2: Modification of cellulose: cellulose extracted from Taxus chinensis is mixed with 2,2,6,6-tetramethylpiperidin-1-oxyl and nano zinc solution, and then ultrasonically dispersed, filtered and dried to obtain the obtained product; Step S3: blending: 50-100 parts of PBAT, 20-60 parts of PLA, 5-20 parts of modified cellulose, 0.5-10 parts of hexafunctional polyurethane acrylate, 0.1-2.0 parts of chain extender, 0.1-0.8 parts of plasticizer, 0.1-1 parts of lubricant, 0.1-0.3 parts of antioxidant, 0.1-0.3 parts of light stabilizer, and 1.0-4.0 parts of talc are mixed in proportion and then put into an internal mixer for blending to obtain a composite material; Step S4: putting the obtained composite material into a flat vulcanizer, setting the upper and lower plates to 190° C. and 200° C. respectively, hot pressing for 3 minutes, and taking out the obtained film after cooling to obtain a biodegradable antibacterial wood-plastic composite film.

[0020] Among them, step S1 specifically includes: raw material pretreatment: first, the yew residue is processed into powder with an ultrafine grinder, and the particle size is 60 mesh to 300 mesh, and then placed in a blast drying oven, dried at 85°C, and dried for 20h to 24h to obtain yew dry powder; ethanol treatment: the yew dry powder is mixed with 95% industrial ethanol, boiled and refluxed for 4 hours, and then washed and dried; alkali treatment: the powder after ethanol treatment is mixed with concentrated NaOH, stirred at 80°C for 2h; pH adjustment: H2SO4 is added to adjust the pH to neutral, and washed; centrifugation and drying: the system is placed in a centrifuge for centrifugal separation, and the solid part is dried to obtain a cellulose product; step S3 specifically includes: the antibacterial enhanced cellulose (modified cellulose) and PLA and PBAT are placed in a vacuum oven and dried at 60°C for 24h; PBAT and PLA are added in a high-speed mixer , modified cellulose, hexafunctional polyurethane acrylate, chain extender, plasticizer, lubricant, and antioxidant were mixed for 5 minutes, and then put into an internal mixer, and the first, second, and third zones were all set to 190°C, the speed was 90R / min, and the blending time was 10min to obtain a biodegradable antibacterial wood-plastic composite material; the structure of the chain extender is ; The plasticizer is tributyl citrate, the lubricant is vinyl bisstearamide, the antioxidant is Irganox 1010, and the light stabilizer is BASF 944. Example 3

[0021] A method for preparing a degradable antibacterial wood-plastic composite film comprises the following steps: Extracting cellulose from the residue after paclitaxel extraction using yew 1. Raw material pretreatment: First, the yew residue is processed into powder with an ultra-fine grinder, and the particle size is 60 mesh to 300 mesh, and then placed in a blast drying oven and dried at 85°C for 20h to 24h to obtain yew dry powder; 2. Ethanol treatment: Mix the dry powder of Taxus chinensis with 95% industrial ethanol, boil and reflux for 4 hours, then wash and dry.

[0022] 3. Alkali treatment: Mix the ethanol-treated powder with concentrated NaOH and stir at 80 °C for 2 h.

[0023] 4. Adjust pH: Add H2SO4 to adjust pH to neutral and wash.

[0024] 5. Centrifugation and drying: Place the system in a centrifuge for centrifugal separation, and dry the solid part to obtain a cellulose product.

[0025] Modification of cellulose The cellulose extracted from the above-mentioned yew was mixed with 2,2,6,6-tetramethylpiperidine-1-oxyl and nano-zinc solution, and then ultrasonically dispersed, filtered and dried. Compared with ordinary cellulose, the antibacterial ability of the treated cellulose is significantly enhanced, and the introduction of 2,2,6,6-tetramethylpiperidine-1-oxyl gives a large number of carboxyl groups on the cellulose surface, reducing the effect of inorganic nanoparticle chelation on the compatibility of cellulose, improving the surface activity of cellulose, and promoting the subsequent composite process.

[0026] Blending 1. Dehydration of substrate: Place the antibacterial enhanced cellulose, PLA and PBAT in a vacuum oven at 60°C and dry for 24 hours.

[0027] 2. Preparation of mixture: Add all materials of a biodegradable antibacterial wood-plastic composite film into a high-speed mixer and mix for 5 minutes.

[0028] 3. Preparation of wood-plastic composite materials: The mixture was put into an internal mixer, and the first, second and third zones were all set to 190° C., the speed was 90 R / min, and the blending time was 10 min to obtain a biodegradable and antibacterial wood-plastic composite material.

[0029] 4. Film preparation: The obtained composite material is placed in a flat vulcanizer, the upper and lower plates are set to 190° C. and 200° C. respectively, hot pressed for 3 minutes, and the obtained film is taken out after cooling to obtain the target product of the present invention, the degradable antibacterial wood-plastic composite film. Example 4

[0030] A degradable antibacterial wood-plastic composite film is composed of the following components: 70 parts of PBAT, 30 parts of PLA, 5 parts of modified cellulose, 0.5 parts of hexafunctional polyurethane acrylate, 0.5 parts of chain extender, 0.3 parts of plasticizer, 0.1 parts of lubricant, 0.1 parts of antioxidant, 0.1 parts of light stabilizer and 2.0 parts of talc.

[0031] in, The antibacterial agent is 0.1% nano zinc solution. The chain extender is copolymerized with styrene, methacrylate glycerol, and carbodiimide. It has multiple epoxy groups and more reaction sites than commonly used chain extenders. Carbodiimide is added, and this group can react with the carboxyl group and free hydrogen generated by hydrolysis to form a stable ureide structure, so that the chain extender has the function of enhancing the hydrolysis resistance of the base material. The structure of the chain extender is shown as follows:

[0032] The chain extension principle of this chain extender is that the epoxy group reacts with the carboxyl and hydroxyl groups in PLA and PBAT, as well as the hydroxyl groups of cellulose to extend the chain and increase the capacity.

[0033] With hydroxyl: With carboxyl group:

[0034] Commonly used chain extenders such as diols and diamines generally contain only two reaction sites. However, this copolymerized chain extender has a significantly increased number of reaction sites due to the synergistic effect of styrene, methacrylate glycerol and carbodiimide, as well as the presence of multiple epoxy groups. It can react with the base material at more locations, thereby more effectively achieving the expansion and cross-linking of the molecular chain and improving the overall performance of the material. Compared with most commonly used chain extenders, the carbodiimide group in this chain extender gives it a unique anti-hydrolysis function. In a humid or harsh use environment, the base material is prone to hydrolysis, resulting in a decrease in performance. This chain extender can inhibit the hydrolysis reaction through the reaction of carbodiimide with the hydrolysis product, maintain the performance stability of the material, and extend the service life of the material, giving it a clear advantage in fields with high requirements for hydrolysis resistance. Among them, the addition of styrene can bring a rigid benzene ring structure to the chain extender, which helps to improve the strength and rigidity of the base material. At the same time, styrene has a high polymerization activity and can participate in the formation of polymer chains in the copolymerization reaction, so that the chain extender and the matrix material have better compatibility, thereby improving the comprehensive performance of the material; methacrylate glycerol: This monomer contains polymerizable double bonds and highly active hydroxyl and ester functional groups. The double bond can participate in the copolymerization reaction, allowing the chain extender to be connected to the polymer main chain; the hydroxyl group provides an active site for reacting with other functional groups, which can further react chemically with the functional groups in the matrix material to enhance the binding force between the chain extender and the matrix; the presence of the ester group also helps to adjust the hydrophilicity and hydrophobicity of the chain extender, thereby affecting the processing performance and final performance of the material; the introduction of the carbodiimide group is one of the key features of this chain extender. It can react with the carboxyl group and free hydrogen produced by hydrolysis to generate a stable ureide structure. This reaction can effectively consume the acidic substances and active hydrogen produced by hydrolysis, thereby preventing the further progress of the hydrolysis reaction and significantly enhancing the anti-hydrolysis performance of the matrix material. The presence of multiple epoxy groups significantly increases the reaction sites of the chain extender. When reacting with the matrix material, the epoxy group can undergo a ring-opening addition reaction with a variety of functional groups containing active hydrogen, such as hydroxyl and amino groups, to form a strong chemical bond. This can not only effectively expand the molecular chain, increase the molecular weight and segment length of the material, but also form a cross-linked network structure in the matrix material, further improving the mechanical properties, heat resistance and dimensional stability of the material.

[0035] Hexafunctional polyurethane acrylate is prepared by addition polymerization of diisocyanate, polyoxypropylene glycol, and pentaerythritol triacrylate. The isocyanate group in the diisocyanate can fully react with the hydroxyl group, and the synthetic product is more uniform with less by-products, thereby reducing the impact of impurities on the performance of the matrix material. At the same time, the molecule contains acrylic functional groups and carbamate bonds, which promote the connection between each molecular chain and help improve the flexibility of the material. The hexafunctional polyurethane acrylate molecule contains both acrylic functional groups and carbamate bonds. During the polymerization process, the acrylic functional group can undergo cross-linking reactions with other molecules containing unsaturated bonds to form a three-dimensional network structure, which increases the cross-linking density and strength of the material, thereby enhancing the reactivity with the chain extender and improving the performance of the material. The carbamate bond itself has good flexibility and elasticity, and can play the role of "flexible connection" between molecular chains, making the connection between each molecular chain more compact and elastic, thereby significantly improving the flexibility of the material. This unique molecular structure allows the material to have high strength while maintaining good flexibility and impact resistance.

[0036] The plasticizer is tributyl citrate. The lubricant is vinyl bis stearamide, The antioxidant is Irganox 1010, The light stabilizer was BASF 944.

[0037] The method for preparing a degradable antibacterial wood-plastic composite film comprises the following steps: 1. Extracting cellulose from the residue after extracting paclitaxel from yew 1. Raw material pretreatment: First, the yew residue is processed into powder using an ultra-fine grinder, passed through a 100-mesh sieve, and then placed in a blast drying oven and dried at 85°C. After drying for 24 hours, the yew dry powder is obtained; 2. Ethanol treatment: Mix the dried yew powder with 95% industrial ethanol, boil and reflux for 4 hours, then wash and dry. Mixing with 95% industrial ethanol, boiling and reflux for 4 hours can effectively remove some alcohol-soluble impurities in the residue, such as residual paclitaxel, pigments, and some small organic molecules. The removal of these impurities helps to improve the purity of cellulose.

[0038] 3. Alkali treatment: Mix the ethanol-treated powder with concentrated NaOH and stir at 80 °C for 2 h.

[0039] 4. Adjust pH: Add H2SO4 to adjust pH to neutral, and wash. Adding H2SO4 to adjust pH to neutral is to neutralize the alkaline substances in the system after alkali treatment, to avoid the adverse effects of residual alkali on the performance of cellulose products, and to prevent the degradation of cellulose or other chemical reactions caused by the alkaline environment during subsequent treatment or use.

[0040] 5. Centrifugation and drying: Place the system in a centrifuge for centrifugal separation, and dry the solid part to obtain a cellulose product. Mix the ethanol-treated powder with concentrated NaOH at 80°C and stir for 2 hours. The main purpose is to use the alkali solution to react chemically with lignin, hemicellulose and other components in cellulose to dissolve or degrade impurities such as lignin and hemicellulose, thereby separating them from cellulose. Alkali treatment can significantly improve the purity and reactivity of cellulose, making it easier for subsequent processing and application.

[0041] 2. Modification of cellulose The cellulose extracted from the above-mentioned yew was mixed with 2,2,6,6-tetramethylpiperidin-1-oxyl and nano zinc solution, and then ultrasonically dispersed, filtered and dried. When the cellulose extracted from the yew was mixed and stirred with TEMPO, TEMPO could react with the functional groups such as hydroxyl groups on the surface of cellulose, which would have a certain surface modification effect on cellulose and change the surface properties of cellulose, thereby enhancing the compatibility and reactivity with hexafunctional polyurethane acrylate and chain extender.

[0042] 3. Blending 1. Dehydration of substrate: Place the antibacterial enhanced cellulose, PLA and PBAT in a vacuum oven at 60°C and dry for 24 hours.

[0043] 2. Preparation of mixture: Add all materials for preparing the biodegradable antibacterial wood-plastic composite film into a high-speed mixer and mix for 5 minutes to prepare a mixture.

[0044] 3. Preparation of wood-plastic composite materials: put the mixture into the internal mixer, set the first, second and third zones to 190℃, the speed to 90R / min, and the blending time to 10min to obtain a degradable antibacterial wood-plastic composite material. The first, second and third zones of the internal mixer are all set to 190℃ so that the mixture can be fully melted and mixed at this temperature. Within this temperature range, polymers such as PLA and PBAT can achieve appropriate fluidity, which is convenient for sufficient physical and chemical reactions with other components such as antibacterial reinforced cellulose to form a uniform composite material structure. If the temperature is too low, the material cannot be fully melted and the mixing effect is poor; if the temperature is too high, it may cause material degradation and affect the performance of the composite material.

[0045] 4. Film preparation: The obtained composite material is placed in a flat vulcanizer, the upper and lower plates are set to 190° C. and 200° C. respectively, hot pressed for 3 minutes, and the obtained film is taken out after cooling to obtain the target product of the present invention, the degradable antibacterial wood-plastic composite film. Example 5

[0046] A degradable antibacterial wood-plastic composite film is composed of the following components: 70 parts of PBAT, 30 parts of PLA, 10 parts of modified cellulose, 1.0 parts of hexafunctional polyurethane acrylate, 1.0 parts of chain extender, 0.3 parts of plasticizer, 0.1 parts of lubricant, 0.2 parts of antioxidant, 0.2 parts of light stabilizer and 2.0 parts of talc.

[0047] in, The antibacterial agent is 0.1% nano zinc solution. The chain extender is made by copolymerization of styrene, glyceryl methacrylate and carbodiimide. Hexafunctional polyurethane acrylate is prepared by addition polymerization of diisocyanate, polyoxypropylene glycol and pentaerythritol triacrylate.

[0048] The plasticizer is tributyl citrate. The lubricant is vinyl bis stearamide, The antioxidant is Irganox 1010, The light stabilizer was BASF 944.

[0049] The method for preparing a degradable antibacterial wood-plastic composite film comprises the following steps: 1. Extracting cellulose from the residue after extracting paclitaxel from yew 1. Raw material pretreatment: First, the yew residue is processed into powder using an ultra-fine grinder, passed through a 100-mesh sieve, and then placed in a blast drying oven and dried at 85°C. After drying for 24 hours, the yew dry powder is obtained; 2. Ethanol treatment: Mix the dry powder of Taxus chinensis with 95% industrial ethanol, boil and reflux for 4 hours, then wash and dry.

[0050] 3. Alkali treatment: Mix the ethanol-treated powder with concentrated NaOH and stir at 80 °C for 2 h.

[0051] 4. Adjust pH: Add H2SO4 to adjust pH to neutral and wash.

[0052] 5. Centrifugation and drying: Place the system in a centrifuge for centrifugal separation, and dry the solid part to obtain a cellulose product.

[0053] 2. Modification of cellulose The cellulose extracted from the above Taxus chinensis is mixed with 2,2,6,6-tetramethylpiperidin-1-oxyl and nano zinc solution, stirred, ultrasonically dispersed, filtered and dried.

[0054] 3. Blending 1. Dehydration of substrate: Place the antibacterial enhanced cellulose, PLA and PBAT in a vacuum oven at 60°C and dry for 24 hours.

[0055] 2. Preparation of mixture: Add all the above materials into a high-speed mixer and mix for 5 minutes to prepare a mixture.

[0056] 3. Preparation of wood-plastic composite materials: The mixture was put into an internal mixer, and the first, second and third zones were all set to 190° C., the speed was 90 R / min, and the blending time was 10 min to obtain a biodegradable and antibacterial wood-plastic composite material.

[0057] 4. Film preparation: The obtained composite material is placed in a flat vulcanizer, the upper and lower plates are set to 190° C. and 200° C. respectively, hot pressed for 3 minutes, and the obtained film is taken out after cooling to obtain the target product of the present invention, the degradable antibacterial wood-plastic composite film. Example 6

[0058] A degradable antibacterial wood-plastic composite film is composed of the following components: 70 parts of PBAT, 30 parts of PLA, 15 parts of modified cellulose, 1.5 parts of hexafunctional polyurethane acrylate, 1.5 parts of chain extender, 0.3 parts of plasticizer, 0.1 parts of lubricant, 0.3 parts of antioxidant, 0.3 parts of light stabilizer and 2.0 parts of talcum powder.

[0059] in, The antibacterial agent is 0.1% nano zinc solution. The chain extender is copolymerized with styrene, glyceryl methacrylate and carbodiimide. The hexafunctional polyurethane acrylate is prepared by addition polymerization of diisocyanate, polyoxypropylene glycol and pentaerythritol triacrylate. The plasticizer is tributyl citrate, The lubricant is vinyl bisstearamide, The antioxidant is Irganox 1010, The light stabilizer is BASF 944.

[0060] A method for preparing a degradable antibacterial wood-plastic composite film comprises the following steps: 1. Extracting cellulose from the residue after extracting paclitaxel from yew 1. Raw material pretreatment: First, the yew residue is processed into powder using an ultra-fine grinder, passed through a 100-mesh sieve, and then placed in a blast drying oven and dried at 85°C. After drying for 24 hours, the yew dry powder is obtained; 2. Ethanol treatment: Mix the dry powder of Taxus chinensis with 95% industrial ethanol, boil and reflux for 4 hours, then wash and dry.

[0061] 3. Alkali treatment: Mix the ethanol-treated powder with concentrated NaOH and stir at 80 °C for 2 h.

[0062] 4. Adjust pH: Add H2SO4 to adjust pH to neutral and wash.

[0063] 5. Centrifugation and drying: Place the system in a centrifuge for centrifugal separation, and dry the solid part to obtain a cellulose product.

[0064] 2. Modification of cellulose The cellulose extracted from the above Taxus chinensis is mixed with 2,2,6,6-tetramethylpiperidin-1-oxyl and nano zinc solution, stirred, ultrasonically dispersed, filtered and dried.

[0065] 3. Blending 1. Dehydration of substrate: Place the antibacterial enhanced cellulose, PLA and PBAT in a vacuum oven at 60°C and dry for 24 hours.

[0066] 2. Preparation of mixture: Add all the above materials into a high-speed mixer and mix for 5 minutes to prepare a mixture.

[0067] 3. Preparation of wood-plastic composite materials: The mixture was put into an internal mixer, and the first, second and third zones were all set to 190° C., the speed was 90 R / min, and the blending time was 10 min to obtain a biodegradable and antibacterial wood-plastic composite material.

[0068] 4. Film preparation: Put the composite material obtained in step 3 into a flat vulcanizer, set the upper and lower plates to 190° C. and 200° C. respectively, and hot press for 3 minutes. After cooling, take out the obtained film to obtain the target product of the present invention, the degradable antibacterial wood-plastic composite film.

[0069] Comparative Example 1: Compared with Example 5, the yew powder is not subjected to cellulose extraction treatment, antibacterial enhancement treatment, and hexafunctional polyurethane acrylate and chain extender are not added.

[0070] Comparative Example 2: Compared with Example 5, the antibacterial enhancer is an unsaturated alkyl quaternary ammonium salt.

[0071] Comparative Example 3: Compared with Example 5, the chain extender is styrene-glycidyl methacrylate oligomer.

[0072] Comparative Example 4: Compared with Example 5, the chain extender adopts propylene oxide.

[0073] Table 1 Performance test: project Stress(MPa) strain(%) Escherichia coli antibacterial rate (%) Degradation start time (days) Example 4 12.6 579 99 21 Example 5 13.1 597 99 23 Example 6 12.3 585 99 25 Comparative Example 1 10.1 260 59 6 Comparative Example 2 11.9 573 91 36 Comparative Example 3 11.4 564 99 26 Comparative Example 4 11.3 527 99 23 The above test adopts the following standards: Tensile test adopts: GB / T 1040.3-2006 Antibacterial test: ASTM E 2149-20 Degradation test adopted: GB / T 33797-2017 As shown in Table 1, the wood-plastic composite film prepared by this scheme has good tensile properties and antibacterial properties. After adding relevant additives, the degradation start time is extended to a certain extent, but it does not fundamentally change its degradability. It can be widely used in the preparation of green packaging and film bags.

[0074] The technical principle of the present invention is described above in combination with the specific embodiments, which are only preferred implementations of the present invention. The protection scope of the present invention is not limited to the above embodiments, and all technical solutions under the idea of ​​the present invention belong to the protection scope of the present invention. Those skilled in the art can think of other specific implementations of the present invention without creative work, and these methods will fall within the protection scope of the present invention.

Claims

1. A degradable antibacterial wood-plastic composite film, characterized in that: The composition includes the following ingredients: 50-100 parts of PBAT; 20-60 parts of PLA; 5-20 parts of modified cellulose; Hexafunctional polyurethane acrylate 0.5-10 parts; chain extender 0.1-2.0 parts; plasticizer 0.1-0.8 parts; lubricant 0.1-1 parts; antioxidant 0.1-0.3 parts, light stabilizer 0.1-0.3 parts, talc 1.0-4.0 parts.

2. The degradable antibacterial wood-plastic composite film according to claim 1, characterized in that: The composition includes the following ingredients: 70 parts of PBAT; 30 parts of PLA; 5 parts of modified cellulose; 0.5 parts of hexafunctional polyurethane acrylate, 0.5 parts of chain extender; 0.3 parts of plasticizer; 0.1 parts of lubricant; 0.1 parts of antioxidant, 0.1 parts of light stabilizer, 2.0 parts of talc.

3. The degradable antibacterial wood-plastic composite film according to claim 1, characterized in that: The composition includes the following components: 70 parts of PBAT; 30 parts of PLA; 10 parts of modified cellulose; 1.0 parts of hexafunctional polyurethane acrylate; 1.0 parts of chain extender; 0.3 parts of plasticizer; 0.1 parts of lubricant; 0.2 parts of antioxidant, 0.2 parts of light stabilizer, 2.0 parts of talc.

4. The degradable antibacterial wood-plastic composite film according to claim 1, characterized in that: The invention comprises the following ingredients: 70 parts of PBAT, 30 parts of PLA, 15 parts of modified cellulose, 1.5 parts of hexafunctional polyurethane acrylate, 1.5 parts of chain extender, 0.3 parts of plasticizer, 0.1 parts of lubricant, 0.3 parts of antioxidant, 0.3 parts of light stabilizer and 2.0 parts of talc.

5. The degradable antibacterial wood-plastic composite film according to claim 2, characterized in that: The modified cellulose is obtained by mixing and stirring cellulose extracted from yew with 2,2,6,6-tetramethylpiperidine-1-oxyl and nano zinc solution, ultrasonically dispersing the mixture, filtering and drying the mixture, wherein the ratio of cellulose extracted from yew, 2,2,6,6-tetramethylpiperidine-1-oxyl and nano zinc solution is 100:(1-10):(1-5), the chain extender is copolymerized with styrene, glyceryl methacrylate and carbodiimide, wherein the ratio of styrene, glyceryl methacrylate and carbodiimide is 1:(0.5-1):(0.1-1), and the hexafunctional polyurethane acrylate is obtained by addition polymerization of diisocyanate, polyoxypropylene glycol and pentaerythritol triacrylate.

6. A method for preparing a degradable antibacterial wood-plastic composite film, characterized in that: The following steps are included: S1: Extract cellulose from the residue after paclitaxel extraction using Taxus chinensis; Step S2: Modification of cellulose: cellulose extracted from Taxus chinensis is mixed with 2,2,6,6-tetramethylpiperidin-1-oxyl and nano zinc solution, and then ultrasonically dispersed, filtered and dried to obtain the obtained product; Step S3: blending: 50-100 parts of PBAT; 20-60 parts of PLA; 5-20 parts of modified cellulose according to the proportion; 0.5-10 parts of hexafunctional polyurethane acrylate, 0.1-2.0 parts of chain extender, 0.1-0.8 parts of plasticizer, 0.1-1 parts of lubricant, 0.1-0.3 parts of antioxidant, 0.1-0.3 parts of light stabilizer and 1.0-4.0 parts of talc are mixed and then put into an internal mixer for blending to obtain a composite material; Step S4: putting the obtained composite material into a flat vulcanizer, setting the upper and lower plates to 190° C. and 200° C. respectively, hot pressing for 3 minutes, and taking out the obtained film after cooling to obtain a biodegradable antibacterial wood-plastic composite film.

7. The method for preparing a degradable antibacterial wood-plastic composite film according to claim 6, characterized in that: The step S1 specifically comprises: raw material pretreatment: firstly, the yew residue is processed into powder with an ultrafine grinder, and the particle size is 60 mesh to 300 mesh, and then placed in a blast drying oven, and dried at 85°C, and dried for 20h to 24h to obtain yew dry powder; ethanol treatment: the yew dry powder is mixed with 95% industrial ethanol, boiled and refluxed for 4 hours, and then washed and dried; alkali treatment: the powder after ethanol treatment is mixed with concentrated NaOH, and stirred at 80°C for 2h; pH adjustment: H2SO4 is added to adjust the pH to neutral, and washed; centrifugation and drying: the system is placed in a centrifuge for centrifugal separation, and the solid part is dried to obtain a cellulose product.

8. The method for preparing a degradable antibacterial wood-plastic composite film according to claim 7, characterized in that: The step S3 specifically includes: placing the modified cellulose, PLA and PBAT in a vacuum oven at 60° C. and drying for 24 hours; adding PBAT, PLA, modified cellulose, hexafunctional polyurethane acrylate, chain extender, plasticizer, lubricant and antioxidant in a high-speed mixer and mixing for 5 minutes, and then placing in an internal mixer, setting the first, second and third zones to 190° C., the speed to 90 R / min, and the blending time to 10 minutes to obtain a degradable antibacterial wood-plastic composite material.

9. The method for preparing a degradable antibacterial wood-plastic composite film according to claim 8, characterized in that: The structure of the chain extender is .

10. The method for preparing a degradable antibacterial wood-plastic composite film according to claim 9, characterized in that: The plasticizer is tributyl citrate, the lubricant is vinyl bisstearamide, the antioxidant is Irganox 1010, and the light stabilizer is BASF 944.

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