Degradable material based on medium-chain and long-chain polyhydroxyalkanoate and preparation method thereof

Abstract

The invention relates to the technical field of degradable materials, in particular to a degradable material based on medium-chain and long-chain polyhydroxyalkanoate and a preparation method thereof.The degradable material comprises a lignocellulose / PHA film and biodegradable CPP films cast on the upper surface and the lower surface of the lignocellulose / PHA film; the lignocellulose / PHA film is prepared from the following components: bamboo-based lignocellulose, PHAMCL, polyvinyl alcohol resin, sodium polyacrylate, toluyl peroxide, sodium persulfate, ethylene glycol, ethanol and deionized water. According to the invention, the bamboo-based lignocellulose is compounded with medium-chain and long-chain polyhydroxyalkanoate, and the adhesion between fibers is enhanced by activating residual lignin and increasing the levels of phenolic hydroxyl groups and carboxyl groups in biomass, so that the barrier ability to water vapor and oxygen is improved; the flexible packaging bag is suitable for packaging bags, bottles, pipes, cans, boxes and other flexible packaging pieces in the industries of food, pharmacy, medical instruments, daily chemicals, stationery and the like.

Description

Technical Field

[0001] The invention relates to the technical field of degradable materials, in particular to a degradable material based on medium- and long-chain polyhydroxyalkanoate and a preparation method thereof. Background Art

[0002] Medium-chain polyhydroxyalkanoates (PHAMCL) are a class of highly biodegradable polymer materials, usually synthesized by microorganisms, with significant characteristics such as environmental protection, degradability and biodegradability. PHAMCL is not a single substance, but a polyester family composed of multiple monomers with different performance characteristics. To date, more than 100 different monomers have been discovered, covering various saturated and unsaturated, linear and branched 3-hydroxy fatty acids with 6 to 16 carbon atoms, some of which also have aliphatic or aromatic side chain structures.

[0003] Lignocellulose is one of the main raw materials for packaging paper. With its good biodegradability, low cost and large-scale production capacity, it has become a potential alternative to plastic packaging. However, packaging paper has large surface pores and poor barrier properties, which limits its wider application. Summary of the invention

[0004] The object of the present invention is to provide a degradable material based on medium- and long-chain polyhydroxyalkanoates and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned purpose, on the one hand, the present invention provides the following technical scheme: a degradable material based on medium- and long-chain polyhydroxyalkanoates, the degradable material comprising a cellulose / PHA film, and a biodegradable CPP film cast on the upper and lower surfaces of the cellulose / PHA film; the cellulose / PHA film comprises the following components by mass: 100 parts of bamboo-based cellulose, 10 to 16 parts of PHAMCL, 10 to 12 parts of polyvinyl alcohol resin, 4 to 6 parts of sodium polyacrylate, 1 to 2 parts of methyl peroxide, 0.5 to 1 part of sodium persulfate, 6 to 8 parts of ethylene glycol, 10 to 12 parts of ethanol and 60 to 80 parts of deionized water.

[0006] Optionally, the particle size of the bamboo-based wood cellulose is 40-60 meshes, and the bamboo-based wood cellulose is composed of green bamboo chips and yellow bamboo chips in a mass ratio of (1-3):1.

[0007] Optionally, the PHAMCL is isolated from a fermentation culture of Pseudomonas mendocinae, and the deposit number of Pseudomonas mendocinae is CCTCC KB 20082656; the steps of obtaining PHAMCL include: inoculating Pseudomonas mendocinae into a culture medium, culturing at 120 rpm and 30°C for 48 hours, and after the fermentation is completed, collecting the cells by centrifugation, washing with sterile water, freeze-drying, refluxing in an 80°C water bath for 12 hours with chloroform as an extract, concentrating the reflux liquid, and precipitating with cold methanol overnight to obtain a white precipitate, which is PHAMCL.

[0008] Optionally, the formula of the culture medium is: 1000 ml of distilled water, 3.8 g of disodium hydrogen phosphate, 2.65 g of potassium dihydrogen phosphate, 0.2 g of magnesium sulfate, 1 mL of trace element solution, 15 g of glucose, and 0.36 g of ammonium chloride; the formula of the trace element solution is: 1000 mL of 0.1 mol / L hydrochloric acid, 0.22 g of cobalt dichloride hexahydrate, 7.8 g of calcium chloride, 0.1 g of chromium trichloride hexahydrate, 0.12 g of nickel chloride, 0.15 g of copper sulfate pentahydrate, and 9.65 g of ferric chloride.

[0009] Optionally, the thickness ratio of the lignocellulose / PHA film and the biodegradable CPP film is (10-50):1, and the biodegradable CPP film comprises the following components by mass: 100 parts of PP homopolymer, 18 parts of PLA resin, 4 parts of PEGT / PBT-based polyether ester, 1 part of erucamide and 0.7 parts of stearic acid glyceryl.

[0010] On the other hand, the present invention also provides the following technical solution: a method for preparing a degradable material based on medium- and long-chain polyhydroxyalkanoates, comprising the following steps: S1. Heating and blending: mixing bamboo-based cellulose, PHAMCL, polyvinyl alcohol resin, methyl phenyl peroxide, sodium persulfate, ethylene glycol, ethanol and deionized water, stirring and heating to 70-76° C., and keeping the temperature for 30-90 min to obtain a suspension; S2, high-pressure homogenization: firstly, the suspension is put into a high-pressure fluid nano-homogenizer, and continuously homogenized at 241.32-275.79 MPa for 1-2 times, then the sodium polyacrylate is put into the high-pressure fluid nano-homogenizer, and continuously homogenized at 137.90-206.84 MPa for 4-5 times, and dehydrated and dried to obtain a mixture; S3, extrusion and casting: add PP homopolymer, PLA resin, PEGT / PBT-based polyether ester, erucic acid amide and stearic acid glyceryl ester to the first and second extruders respectively, set the temperature of the first and second extruders to 140-190°C, the rotation speed to 30-60rpm, melt and plasticize to obtain biodegradable CPP resin, add the mixture to the third extruder, set the temperature of the third extruder to 155-200°C, the rotation speed to 20-70rpm, melt and plasticize to obtain cellulose / PHA resin, the two groups of biodegradable CPP resins are respectively located on the upper and lower sides of the cellulose / PHA resin and cast with it through a co-extrusion die, control the co-extrusion die molding temperature to 170-190°C, and obtain the degradable material.

[0011] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention uses bamboo-based lignocellulose and medium- and long-chain polyhydroxyalkanoates to enhance the adhesion between fibers by activating the residual lignin and increasing the levels of phenolic hydroxyl and carboxyl groups in the biomass, thereby improving the barrier capacity to water vapor and oxygen. The present invention is suitable for packaging bags, bottles, tubes, cans, boxes and other soft packaging in the food, pharmaceutical, medical device, daily chemical, stationery and other industries; 2. The present invention adopts lignocellulose / PHA film and biodegradable CPP film for cast composite. Both lignocellulose / PHA film and biodegradable CPP film are degradable materials, which can be decomposed by microorganisms in the natural environment to reduce pollution to the environment. The biodegradable CPP film has excellent tensile strength, tear resistance and impact resistance, good forming stability, and effectively enhances the mechanical properties of the lignocellulose / PHA film. DETAILED DESCRIPTION

[0012] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0013] Embodiment 1: The present invention provides a degradable material based on medium- and long-chain polyhydroxyalkanoates, the degradable material comprising a lignocellulose / PHA film, and a biodegradable CPP film cast on the upper and lower surfaces of the lignocellulose / PHA film. The lignocellulose / PHA film comprises the following components by mass: 100 parts of bamboo-based lignocellulose, 10 parts of PHAMCL, 10 parts of polyvinyl alcohol resin, 4 parts of sodium polyacrylate, 1 part of toluyl peroxide, 0.5 parts of sodium persulfate, 6 parts of ethylene glycol, 10 parts of ethanol and 60 parts of deionized water. The thickness ratio of the lignocellulose / PHA film and the biodegradable CPP film is 10:1, and the biodegradable CPP film comprises the following components by mass: 100 parts of PP homopolymer, 18 parts of PLA resin, 4 parts of PEGT / PBT-based polyether ester, 1 part of erucamide and 0.7 parts of stearic acid glyceryl. The bamboo-based lignocellulose is composed of green bamboo debris and yellow bamboo debris in a mass ratio of 1:1.

[0014] The present invention also provides a method for preparing the above-mentioned degradable material based on medium- and long-chain polyhydroxyalkanoates, comprising the following steps: S1. Heating and blending: mixing bamboo-based lignocellulose, PHAMCL, polyvinyl alcohol resin, methyl benzoyl peroxide, sodium persulfate, ethylene glycol, ethanol and deionized water, stirring and heating to 70° C., keeping the temperature for 30 min, to obtain a suspension; S2, high-pressure homogenization: firstly, the suspension is put into a high-pressure fluid nano-homogenizer, and homogenized continuously at 241.32 MPa for one time, and then the sodium polyacrylate is put into a high-pressure fluid nano-homogenizer, and homogenized continuously at 137.90 MPa for four times, and then dehydrated and dried to obtain a mixture; S3, extrusion and casting: add PP homopolymer, PLA resin, PEGT / PBT-based polyether ester, erucic acid amide and stearic acid glyceryl ester to the first and second extruders respectively, set the temperature of the first and second extruders to 140°C, the rotation speed to 30rpm, melt and plasticize to obtain biodegradable CPP resin, add the mixture to the third extruder, set the temperature of the third extruder to 155°C, the rotation speed to 20rpm, melt and plasticize to obtain cellulose / PHA resin, the two groups of biodegradable CPP resins are respectively located on the upper and lower sides of the cellulose / PHA resin and cast with it through a co-extrusion die, control the co-extrusion die molding temperature to 170°C, and obtain a degradable material.

[0015] Embodiment 2: The present invention provides a degradable material based on medium- and long-chain polyhydroxyalkanoates, the degradable material comprising a lignocellulose / PHA film, and a biodegradable CPP film cast on the upper and lower surfaces of the lignocellulose / PHA film. The lignocellulose / PHA film comprises the following components by mass: 100 parts of bamboo-based lignocellulose, 12 parts of PHAMCL, 11 parts of polyvinyl alcohol resin, 5 parts of sodium polyacrylate, 1.5 parts of benzoyl peroxide and 0.7 parts of sodium persulfate, 7 parts of ethylene glycol, 11 parts of ethanol and 70 parts of deionized water. The thickness ratio of the lignocellulose / PHA film and the biodegradable CPP film is 25:1, and the biodegradable CPP film comprises the following components by mass: 100 parts of PP homopolymer, 18 parts of PLA resin, 4 parts of PEGT / PBT-based polyether ester, 1 part of erucamide and 0.7 parts of stearic acid glyceryl. The bamboo-based lignocellulose is composed of green bamboo debris and yellow bamboo debris in a mass ratio of 2:1.

[0016] The present invention also provides a method for preparing the above-mentioned degradable material based on medium- and long-chain polyhydroxyalkanoates, comprising the following steps: S1. Heating and blending: mixing bamboo-based cellulose, PHAMCL, polyvinyl alcohol resin, methyl benzoyl peroxide, sodium persulfate, ethylene glycol, ethanol and deionized water, stirring and heating to 72° C., keeping the temperature for 55 min, and obtaining a suspension; S2, high-pressure homogenization: firstly, the suspension is put into a high-pressure fluid nano-homogenizer, and homogenized continuously at 258.55 MPa for one time, then the sodium polyacrylate is put into a high-pressure fluid nano-homogenizer, and homogenized continuously at 172.37 MPa for four times, and then dehydrated and dried to obtain a mixture; S3, extrusion and casting: add PP homopolymer, PLA resin, PEGT / PBT-based polyether ester, erucic acid amide and stearic acid glyceryl ester to the first and second extruders respectively, set the temperature of the first and second extruders to 160°C, the rotation speed to 40rpm, melt and plasticize to obtain biodegradable CPP resin, add the mixture to the third extruder, set the temperature of the third extruder to 170°C, the rotation speed to 30rpm, melt and plasticize to obtain cellulose / PHA resin, the two groups of biodegradable CPP resins are respectively located on the upper and lower sides of the cellulose / PHA resin and cast with it through a co-extrusion die, control the co-extrusion die molding temperature to 180°C, and obtain a degradable material.

[0017] Embodiment 3: The present invention provides a degradable material based on medium- and long-chain polyhydroxyalkanoates, the degradable material comprising a lignocellulose / PHA film, and a biodegradable CPP film cast on the upper and lower surfaces of the lignocellulose / PHA film. The lignocellulose / PHA film comprises the following components by mass: 100 parts of bamboo-based lignocellulose, 14 parts of PHAMCL, 11 parts of polyvinyl alcohol resin, 5 parts of sodium polyacrylate, 1.8 parts of benzoyl peroxide, 0.8 parts of sodium persulfate, 7 parts of ethylene glycol, 11 parts of ethanol and 75 parts of deionized water. The thickness ratio of the lignocellulose / PHA film and the biodegradable CPP film is 45:1, and the biodegradable CPP film comprises the following components by mass: 100 parts of PP homopolymer, 18 parts of PLA resin, 4 parts of PEGT / PBT-based polyether ester, 1 part of erucamide and 0.7 parts of stearic acid glyceryl. The bamboo-based lignocellulose is composed of green bamboo debris and yellow bamboo debris in a mass ratio of 2:1.

[0018] The present invention also provides a method for preparing the above-mentioned degradable material based on medium- and long-chain polyhydroxyalkanoates, comprising the following steps: S1. Heating and blending: mixing bamboo-based lignocellulose, PHAMCL, polyvinyl alcohol resin, methyl benzoyl peroxide, sodium persulfate, ethylene glycol, ethanol and deionized water, stirring and heating to 74° C., keeping the temperature for 70 min, and obtaining a suspension; S2, high-pressure homogenization: firstly, the suspension is put into a high-pressure fluid nano-homogenizer, and homogenized continuously for 2 times at 272.34 MPa, then the sodium polyacrylate is put into a high-pressure fluid nano-homogenizer, and homogenized continuously for 5 times at 189.61 MPa, and dehydrated and dried to obtain a mixture; S3, extrusion and casting: add PP homopolymer, PLA resin, PEGT / PBT-based polyether ester, erucic acid amide and stearic acid glyceryl ester to the first and second extruders respectively, set the temperature of the first and second extruders to 180°C, the rotation speed to 50rpm, melt and plasticize to obtain biodegradable CPP resin, add the mixture to the third extruder, set the temperature of the third extruder to 185°C, the rotation speed to 60rpm, melt and plasticize to obtain cellulose / PHA resin, the two groups of biodegradable CPP resins are respectively located on the upper and lower sides of the cellulose / PHA resin and cast with it through a co-extrusion die, control the co-extrusion die molding temperature to 185°C, and obtain a degradable material.

[0019] Embodiment 4: The present invention provides a degradable material based on medium- and long-chain polyhydroxyalkanoates, the degradable material comprising a lignocellulose / PHA film, and a biodegradable CPP film cast on the upper and lower surfaces of the lignocellulose / PHA film. The lignocellulose / PHA film comprises the following components by mass: 100 parts of bamboo-based lignocellulose, 16 parts of PHAMCL, 12 parts of polyvinyl alcohol resin, 6 parts of sodium polyacrylate, 2 parts of benzoyl peroxide, 1 part of sodium persulfate, 8 parts of ethylene glycol, 12 parts of ethanol and 80 parts of deionized water. The thickness ratio of the lignocellulose / PHA film to the biodegradable CPP film is 50:1, and the biodegradable CPP film comprises the following components by mass: 100 parts of PP homopolymer, 18 parts of PLA resin, 4 parts of PEGT / PBT-based polyether ester, 1 part of erucamide and 0.7 parts of stearic acid glyceryl. The bamboo-based lignocellulose is composed of green bamboo debris and yellow bamboo debris in a mass ratio of 3:1.

[0020] The present invention also provides a method for preparing the above-mentioned degradable material based on medium- and long-chain polyhydroxyalkanoates, comprising the following steps: S1. Heating and blending: mixing bamboo-based lignocellulose, PHAMCL, polyvinyl alcohol resin, toluyl peroxide, sodium persulfate, ethylene glycol, ethanol and deionized water, stirring and heating to 76° C., keeping the temperature for 90 min, to obtain a suspension; S2, high-pressure homogenization: firstly, the suspension is put into a high-pressure fluid nano-homogenizer, and homogenized continuously for 2 times at 275.79 MPa, then the sodium polyacrylate is put into a high-pressure fluid nano-homogenizer, and homogenized continuously for 5 times at 206.84 MPa, and dehydrated and dried to obtain a mixture; S3, extrusion and casting: add PP homopolymer, PLA resin, PEGT / PBT-based polyether ester, erucic acid amide and stearic acid glyceryl ester to the first and second extruders respectively, set the temperature of the first and second extruders to 190°C, the rotation speed to 60rpm, melt and plasticize to obtain biodegradable CPP resin, add the mixture to the third extruder, set the temperature of the third extruder to 200°C, the rotation speed to 70rpm, melt and plasticize to obtain cellulose / PHA resin, the two groups of biodegradable CPP resins are respectively located on the upper and lower sides of the cellulose / PHA resin and cast with it through a co-extrusion die, control the co-extrusion die molding temperature to 190°C, and obtain a degradable material.

[0021] In Examples 1 to 4, the particle size of the bamboo-based cellulose is 40 to 60 meshes, and PHAMCL is isolated from a fermentation culture of Pseudomonas mendocinae, and the deposit number of Pseudomonas mendocinae is CCTCC KB 20082656; the steps of obtaining PHAMCL include: inoculating Pseudomonas mendocinae into a culture medium, culturing at 120 rpm and 30°C for 48 hours, and after the fermentation is completed, collecting the cells by centrifugation, washing with sterile water, freeze-drying, refluxing in a water bath at 80°C for 12 hours with chloroform as an extract, concentrating the reflux liquid, and precipitating with cold methanol overnight to obtain a white precipitate, namely PHAMCL.

[0022] In addition, the formula of the culture medium is: 1000ml of distilled water, 3.8g of disodium hydrogen phosphate, 2.65g of potassium dihydrogen phosphate, 0.2g of magnesium sulfate, 1mL of trace element solution, 15g of glucose, and 0.36g of ammonium chloride; the formula of the trace element solution is: 1000mL of 0.1mol / L hydrochloric acid, 0.22g of cobalt dichloride hexahydrate, 7.8g of calcium chloride, 0.1g of chromium trichloride hexahydrate, 0.12g of nickel chloride, 0.15g of copper sulfate pentahydrate, and 9.65g of ferric chloride.

[0023] Test example Test content: The biodegradable materials prepared in Examples 1 to 4 were taken as the test group, and the biodegradable CPP film of the same thickness as the test group was taken as the control group. The formula of the control group adopted the content disclosed in Examples 1 to 4, and the control group was formed by injection extrusion, and the extrusion temperature was 190°C. The test group and the control group were tested according to the "Cup Weight Gain and Weight Loss Method for Determination of Water Vapor Transmission Rate of Plastic Films and Sheets" (GB / T 1037-2021) and "Test Method for Gas Permeability of Plastic Films and Sheets Part 1: Differential Pressure Method" (GB / T 1038.1-2022), and the water vapor transmission rate and oxygen transmission rate were statistically calculated, and the results are recorded in Table 1.

[0024] Table 1

[0025] It can be seen from Table 1 that the degradable materials prepared in Examples 1 to 4 have good water vapor and oxygen barrier capabilities, and Example 4 has the best water vapor and oxygen barrier capabilities, and is worthy of promotion and use.

[0026] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A degradable material based on medium- and long-chain polyhydroxyalkanoates, characterized in that: The degradable material includes a lignocellulose / PHA film and a biodegradable CPP film cast on the upper and lower surfaces of the lignocellulose / PHA film; the lignocellulose / PHA film includes the following components by mass: 100 parts of bamboo-based lignocellulose, 10 to 16 parts of PHAMCL, 10 to 12 parts of polyvinyl alcohol resin, 4 to 6 parts of sodium polyacrylate, 1 to 2 parts of toluoyl peroxide, 0.5 to 1 part of sodium persulfate, 6 to 8 parts of ethylene glycol, 10 to 12 parts of ethanol and 60 to 80 parts of deionized water.

2. A degradable material based on medium- and long-chain polyhydroxyalkanoates according to claim 1, characterized in that: The particle size of the bamboo-based wood cellulose is 40-60 meshes, and the bamboo-based wood cellulose is composed of green bamboo debris and yellow bamboo debris in a mass ratio of (1-3):

1.

3. A degradable material based on medium- and long-chain polyhydroxyalkanoates according to claim 1, characterized in that: The PHAMCL is isolated from the fermentation culture of Pseudomonas mendocinae, and the deposit number of Pseudomonas mendocinae is CCTCC KB 20082656; The steps of obtaining PHAMCL include: inoculating Pseudomonas mendocinae into a culture medium, culturing at 120 rpm and 30°C for 48 hours, collecting the cells by centrifugation after the fermentation is completed, washing with sterile water, freeze-drying, refluxing in an 80°C water bath for 12 hours using chloroform as an extract, concentrating the reflux liquid, and precipitating with cold methanol overnight to obtain a white precipitate, which is PHAMCL.

4. A degradable material based on medium- and long-chain polyhydroxyalkanoates according to claim 3, characterized in that: The formula of the culture medium is: 1000 ml of distilled water, 3.8 g of disodium hydrogen phosphate, 2.65 g of potassium dihydrogen phosphate, 0.2 g of magnesium sulfate, 1 mL of trace element solution, 15 g of glucose, and 0.36 g of ammonium chloride; the formula of the trace element solution is: 1000 mL of 0.1 mol / L hydrochloric acid, 0.22 g of cobalt dichloride hexahydrate, 7.8 g of calcium chloride, 0.1 g of chromium trichloride hexahydrate, 0.12 g of nickel chloride, 0.15 g of copper sulfate pentahydrate, and 9.65 g of ferric chloride.

5. The degradable material based on medium- and long-chain polyhydroxyalkanoates according to claim 1, characterized in that: The thickness ratio of the lignocellulose / PHA film to the biodegradable CPP film is (10-50):1, and the biodegradable CPP film comprises the following components by mass: 100 parts of PP homopolymer, 18 parts of PLA resin, 4 parts of PEGT / PBT-based polyether ester, 1 part of erucamide and 0.7 parts of stearic acid glyceryl.

6. A method for preparing a degradable material based on medium- and long-chain polyhydroxyalkanoates according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Heating and blending: mixing bamboo-based lignocellulose, PHAMCL, polyvinyl alcohol resin, methyl benzoyl peroxide, sodium persulfate, ethylene glycol, ethanol and deionized water, stirring and heating to 70-76° C., and keeping the temperature for 30-90 min to obtain a suspension; S2, high-pressure homogenization: firstly, the suspension is put into a high-pressure fluid nano-homogenizer, and continuously homogenized at 241.32-275.79 MPa for 1-2 times, then the sodium polyacrylate is put into the high-pressure fluid nano-homogenizer, and continuously homogenized at 137.90-206.84 MPa for 4-5 times, and dehydrated and dried to obtain a mixture; S3, extrusion and casting: add PP homopolymer, PLA resin, PEGT / PBT-based polyether ester, erucic acid amide and stearic acid glyceryl ester to the first and second extruders respectively, set the temperature of the first and second extruders to 140-190°C, the rotation speed to 30-60rpm, melt and plasticize to obtain biodegradable CPP resin, add the mixture to the third extruder, set the temperature of the third extruder to 155-200°C, the rotation speed to 20-70rpm, melt and plasticize to obtain cellulose / PHA resin, the two groups of biodegradable CPP resins are respectively located on the upper and lower sides of the cellulose / PHA resin and cast with it through a co-extrusion die, control the co-extrusion die molding temperature to 170-190°C, and obtain the degradable material.

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