A degradable material based on medium and long chain polyhydroxyalkanoate and a preparation method thereof

Abstract

The application 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, which comprises 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: bamboo-based lignocellulose, PHA MCL, polyvinyl alcohol resin, sodium polyacrylate, toluene-p-xylyl peroxide, sodium persulfate, ethylene glycol, ethanol and deionized water. The bamboo-based lignocellulose and the medium and long chain polyhydroxyalkanoate are compounded, the adhesion between fibers is enhanced by activating the residual lignin and increasing the level of phenolic hydroxyl and carboxyl in the biomass, the barrier ability to water vapor and oxygen is improved, and the application is suitable for the packaging bags, bottles, tubes, cans, boxes and other soft packaging parts of the food, pharmaceutical, medical device, daily chemical, stationery and other industries.

Description

Technical Field

[0001] This invention relates to the field of biodegradable materials technology, specifically to a biodegradable material based on medium- and long-chain polyhydroxy fatty acid esters and its preparation method. Background Technology

[0002] Medium- and long-chain polyhydroxyalkanoates (PHAMCLs) are a class of highly biodegradable polymers, typically synthesized by microorganisms, and possess significant characteristics such as environmental friendliness, biodegradability, and biodegradability. PHAMCLs are not a single substance but rather a family of polyesters composed of various monomers with different performance characteristics. To date, over 100 different monomers have been discovered, encompassing various saturated and unsaturated, straight-chain and branched 3-hydroxy fatty acids with 6 to 16 carbon atoms, some of which also possess aliphatic or aromatic side-chain structures.

[0003] Lignocellulose is one of the most important raw materials in packaging paper production. Its good biodegradability, low cost, and large-scale production capacity have made it a potential alternative to plastic packaging. However, the large surface porosity and poor barrier properties of packaging paper limit its wider application. Summary of the Invention

[0004] The purpose of this invention is to provide a biodegradable material based on medium- and long-chain polyhydroxy fatty acid esters and its preparation method, so as to solve the problems mentioned in the background art.

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

[0006] Optionally, the bamboo-based lignocellulose has a particle size of 40-60 mesh and is composed of moso bamboo green fragments and moso bamboo yellow fragments in a mass ratio of (1-3):1.

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

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

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

[0010] On the other hand, the present invention also provides the following technical solution: a method for preparing a biodegradable material based on medium- and long-chain polyhydroxy fatty acid esters, comprising the following steps:

[0011] S1. Heating and blending: Bamboo-based lignocellulose, PHAMCL, polyvinyl alcohol resin, toluene peroxide, sodium persulfate, ethylene glycol, ethanol and deionized water are mixed, stirred and heated to 70-76℃, and kept at this temperature for 30-90 minutes to obtain a suspension.

[0012] S2. High-pressure homogenization: First, the suspension is put into a high-pressure fluid nano-homogenizer and homogenized continuously 1 to 2 times at 241.32 to 275.79 MPa. Then, sodium polyacrylate is put into the high-pressure fluid nano-homogenizer and homogenized continuously 4 to 5 times at 137.90 to 206.84 MPa. After dehydration and drying, a mixture is obtained.

[0013] S3. Extrusion and Casting: PP homopolymer, PLA resin, PEGT / PBT-based polyether ester, erucamide, and glyceryl stearate are added to the first and second extruders respectively. The temperatures of the first and second extruders are set to 140–190°C and the rotation speed is set to 30–60 rpm. After melting and plasticizing, biodegradable CPP resin is obtained. The mixture is added to the third extruder. The temperature of the third extruder is set to 155–200°C and the rotation speed is set to 20–70 rpm. After melting and plasticizing, lignocellulose / PHA resin is obtained. The two groups of biodegradable CPP resin are located on the upper and lower sides of the lignocellulose / PHA resin respectively and are cast through a co-extrusion die. The forming temperature of the co-extrusion die is controlled at 170–190°C to obtain the biodegradable material.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. This invention uses bamboo-based lignocellulose and medium- and long-chain polyhydroxy fatty acid esters to enhance the adhesion between fibers by activating residual lignin and increasing the levels of phenolic hydroxyl and carboxyl groups in biomass, thereby improving the barrier properties against water vapor and oxygen. It is suitable for flexible packaging such as bags, bottles, tubes, cans, and boxes in the food, pharmaceutical, medical device, daily chemical, and stationery industries.

[0016] 2. This invention uses lignocellulose / PHA film and biodegradable CPP film for casting composite. Both lignocellulose / PHA film and biodegradable CPP film are biodegradable materials that can be decomposed by microorganisms in the natural environment, reducing environmental pollution. Biodegradable CPP film has good tensile strength, tear resistance and impact resistance, good forming stability, and effectively enhances the mechanical properties of lignocellulose / PHA film. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1: This invention provides a biodegradable material based on medium- and long-chain polyhydroxyalkanoates (PHA). The biodegradable material includes a lignocellulose / PHA membrane and a biodegradable CPP film cast on the upper and lower surfaces of the lignocellulose / PHA membrane. The lignocellulose / PHA membrane comprises, by weight, the following components: 100 parts bamboo-based lignocellulose, 10 parts PHAMCL, 10 parts polyvinyl alcohol resin, 4 parts sodium polyacrylate, 1 part benzoyl peroxide, 0.5 parts sodium persulfate, 6 parts ethylene glycol, 10 parts ethanol, and 60 parts deionized water. The thickness ratio of the lignocellulose / PHA membrane to the biodegradable CPP film is 10:1. The biodegradable CPP film comprises, by weight, the following components: 100 parts PP homopolymer, 18 parts PLA resin, 4 parts PEGT / PBT-based polyether ester, 1 part erucamide, and 0.7 parts glyceryl stearate. The bamboo-based lignocellulose is composed of bamboo green and yellow fragments in a 1:1 weight ratio.

[0019] This invention also provides a method for preparing the above-mentioned biodegradable material based on medium- and long-chain polyhydroxy fatty acid esters, comprising the following steps:

[0020] S1. Heating and blending: Bamboo-based lignocellulose, PHAMCL, polyvinyl alcohol resin, toluene peroxide, sodium persulfate, ethylene glycol, ethanol and deionized water are mixed, stirred and heated to 70°C, and kept at this temperature for 30 minutes to obtain a suspension.

[0021] S2. High-pressure homogenization: First, the suspension is put into a high-pressure fluid nano-homogenizer and homogenized once continuously at 241.32 MPa. Then, sodium polyacrylate is put into the high-pressure fluid nano-homogenizer and homogenized four times continuously at 137.90 MPa. After dehydration and drying, a mixture is obtained.

[0022] S3. Extrusion and Casting: PP homopolymer, PLA resin, PEGT / PBT-based polyether ester, erucamide, and glyceryl stearate are added to the first and second extruders respectively. The temperature of the first and second extruders is set to 140℃ and the rotation speed is 30 rpm. After melting and plasticizing, biodegradable CPP resin is obtained. The mixture is added to the third extruder. The temperature of the third extruder is set to 155℃ and the rotation speed is 20 rpm. After melting and plasticizing, lignocellulose / PHA resin is obtained. The two groups of biodegradable CPP resin are located on the upper and lower sides of the lignocellulose / PHA resin respectively and cast through a co-extrusion die. The forming temperature of the co-extrusion die is controlled at 170℃ to obtain the biodegradable material.

[0023] Example 2: This invention provides a biodegradable material based on medium- and long-chain polyhydroxyalkanoates (PHA). The biodegradable material includes a lignocellulose / PHA membrane and a biodegradable CPP film cast on the upper and lower surfaces of the lignocellulose / PHA membrane. The lignocellulose / PHA membrane comprises, by weight, the following components: 100 parts bamboo-based lignocellulose, 12 parts PHAMCL, 11 parts polyvinyl alcohol resin, 5 parts sodium polyacrylate, 1.5 parts benzoyl peroxide, 0.7 parts sodium persulfate, 7 parts ethylene glycol, 11 parts ethanol, and 70 parts deionized water. The thickness ratio of the lignocellulose / PHA membrane to the biodegradable CPP film is 25:1. The biodegradable CPP film comprises, by weight, the following components: 100 parts PP homopolymer, 18 parts PLA resin, 4 parts PEGT / PBT-based polyether ester, 1 part erucamide, and 0.7 parts glyceryl stearate. The bamboo-based lignocellulose is composed of bamboo green and bamboo yellow fragments in a weight ratio of 2:1.

[0024] This invention also provides a method for preparing the above-mentioned biodegradable material based on medium- and long-chain polyhydroxy fatty acid esters, comprising the following steps:

[0025] S1. Heating and blending: Bamboo-based lignocellulose, PHAMCL, polyvinyl alcohol resin, toluene peroxide, sodium persulfate, ethylene glycol, ethanol and deionized water are mixed, stirred and heated to 72°C, and kept at that temperature for 55 min to obtain a suspension.

[0026] S2. High-pressure homogenization: First, the suspension is put into a high-pressure fluid nano-homogenizer and homogenized once continuously at 258.55 MPa. Then, sodium polyacrylate is put into the high-pressure fluid nano-homogenizer and homogenized four times continuously at 172.37 MPa. After dehydration and drying, a mixture is obtained.

[0027] S3. Extrusion and Casting: PP homopolymer, PLA resin, PEGT / PBT-based polyether ester, erucamide, and glyceryl stearate are added to the first and second extruders respectively. The temperature of the first and second extruders is set to 160℃ and the rotation speed is 40 rpm. After melting and plasticizing, biodegradable CPP resin is obtained. The mixture is added to the third extruder. The temperature of the third extruder is set to 170℃ and the rotation speed is 30 rpm. After melting and plasticizing, lignocellulose / PHA resin is obtained. The two groups of biodegradable CPP resin are located on the upper and lower sides of the lignocellulose / PHA resin respectively and cast through a co-extrusion die. The forming temperature of the co-extrusion die is controlled at 180℃ to obtain the biodegradable material.

[0028] Example 3: This invention provides a biodegradable material based on medium- and long-chain polyhydroxyalkanoates (PHA). The biodegradable material includes a lignocellulose / PHA membrane and a biodegradable CPP film cast on the upper and lower surfaces of the lignocellulose / PHA membrane. The lignocellulose / PHA membrane comprises, by weight, the following components: 100 parts bamboo-based lignocellulose, 14 parts PHAMCL, 11 parts polyvinyl alcohol resin, 5 parts sodium polyacrylate, 1.8 parts benzoyl peroxide, 0.8 parts sodium persulfate, 7 parts ethylene glycol, 11 parts ethanol, and 75 parts deionized water. The thickness ratio of the lignocellulose / PHA membrane to the biodegradable CPP film is 45:1. The biodegradable CPP film comprises, by weight, the following components: 100 parts PP homopolymer, 18 parts PLA resin, 4 parts PEGT / PBT-based polyether ester, 1 part erucamide, and 0.7 parts glyceryl stearate. The bamboo-based lignocellulose is composed of bamboo green and yellow fragments in a weight ratio of 2:1.

[0029] This invention also provides a method for preparing the above-mentioned biodegradable material based on medium- and long-chain polyhydroxy fatty acid esters, comprising the following steps:

[0030] S1. Heating and blending: Bamboo-based lignocellulose, PHAMCL, polyvinyl alcohol resin, toluene peroxide, sodium persulfate, ethylene glycol, ethanol and deionized water are mixed, stirred and heated to 74°C, and kept at this temperature for 70 min to obtain a suspension.

[0031] S2. High-pressure homogenization: First, the suspension is put into a high-pressure fluid nano-homogenizer and homogenized twice at 272.34 MPa. Then, sodium polyacrylate is put into the high-pressure fluid nano-homogenizer and homogenized five times at 189.61 MPa. After dehydration and drying, a mixture is obtained.

[0032] S3. Extrusion and Casting: PP homopolymer, PLA resin, PEGT / PBT-based polyether ester, erucamide, and glyceryl stearate are added to the first and second extruders respectively. The temperature of the first and second extruders is set to 180℃ and the rotation speed is 50 rpm. After melting and plasticizing, biodegradable CPP resin is obtained. The mixture is added to the third extruder. The temperature of the third extruder is set to 185℃ and the rotation speed is 60 rpm. After melting and plasticizing, lignocellulose / PHA resin is obtained. The two groups of biodegradable CPP resin are located on the upper and lower sides of the lignocellulose / PHA resin respectively and cast through a co-extrusion die. The forming temperature of the co-extrusion die is controlled at 185℃ to obtain the biodegradable material.

[0033] Example 4: This invention provides a biodegradable material based on medium- and long-chain polyhydroxyalkanoates (PHA). The biodegradable material includes a lignocellulose / PHA membrane and a biodegradable CPP film cast on the upper and lower surfaces of the lignocellulose / PHA membrane. The lignocellulose / PHA membrane comprises, by weight, the following components: 100 parts bamboo-based lignocellulose, 16 parts PHAMCL, 12 parts polyvinyl alcohol resin, 6 parts sodium polyacrylate, 2 parts benzoyl peroxide, 1 part sodium persulfate, 8 parts ethylene glycol, 12 parts ethanol, and 80 parts deionized water. The thickness ratio of the lignocellulose / PHA membrane to the biodegradable CPP film is 50:1. The biodegradable CPP film comprises, by weight, the following components: 100 parts PP homopolymer, 18 parts PLA resin, 4 parts PEGT / PBT-based polyether ester, 1 part erucamide, and 0.7 parts glyceryl stearate. The bamboo-based lignocellulose is composed of bamboo green and yellow fragments in a weight ratio of 3:1.

[0034] This invention also provides a method for preparing the above-mentioned biodegradable material based on medium- and long-chain polyhydroxy fatty acid esters, comprising the following steps:

[0035] S1. Heating and blending: Bamboo-based lignocellulose, PHAMCL, polyvinyl alcohol resin, toluene peroxide, sodium persulfate, ethylene glycol, ethanol and deionized water are mixed, stirred and heated to 76°C, and kept at that temperature for 90 min to obtain a suspension.

[0036] S2. High-pressure homogenization: First, the suspension is put into a high-pressure fluid nano-homogenizer and homogenized twice at 275.79 MPa. Then, sodium polyacrylate is put into the high-pressure fluid nano-homogenizer and homogenized five times at 206.84 MPa. After dehydration and drying, a mixture is obtained.

[0037] S3. Extrusion and Casting: PP homopolymer, PLA resin, PEGT / PBT-based polyether ester, erucamide, and glyceryl stearate are added to the first and second extruders respectively. The temperature of the first and second extruders is set to 190℃ and the rotation speed is 60 rpm. After melting and plasticizing, biodegradable CPP resin is obtained. The mixture is added to the third extruder. The temperature of the third extruder is set to 200℃ and the rotation speed is 70 rpm. After melting and plasticizing, lignocellulose / PHA resin is obtained. The two groups of biodegradable CPP resin are located on the upper and lower sides of the lignocellulose / PHA resin respectively and cast through a co-extrusion die. The forming temperature of the co-extrusion die is controlled at 190℃ to obtain the biodegradable material.

[0038] In Examples 1-4, the particle size of bamboo-based lignocellulose was 40-60 mesh. PHAMCL was isolated from the fermentation culture of Pseudomonas mendoza, whose preservation number was CCTCC KB 20082656. The steps to obtain PHAMCL included: inoculating Pseudomonas mendoza into a culture medium and culturing it at 120 rpm and 30°C for 48 h. After fermentation, the cells were collected by centrifugation, washed with sterile water, freeze-dried, and refluxed in an 80°C water bath for 12 h with chloroform as the extraction solution. The reflux solution was concentrated and precipitated overnight with cold methanol to obtain a white precipitate, which was PHAMCL.

[0039] In addition, the culture medium formula is as follows: 1000ml distilled water, 3.8g disodium hydrogen phosphate, 2.65g potassium dihydrogen phosphate, 0.2g magnesium sulfate, 1mL trace element solution, 15g glucose, and 0.36g ammonium chloride; the trace element solution formula is as follows: 1000mL 0.1mol / L hydrochloric acid, 0.22g cobalt dichloride hexahydrate, 7.8g calcium chloride, 0.1g chromium trichloride hexahydrate, 0.12g nickel chloride, 0.15g copper sulfate pentahydrate, and 9.65g ferric chloride.

[0040] Test case

[0041] Experimental Procedure: The biodegradable materials prepared in Examples 1-4 were used as the experimental group, and a biodegradable CPP film of the same thickness as the experimental group was used as the control group. The formulation of the control group was the same as that disclosed in Examples 1-4. The control group was injection molded at an extrusion temperature of 190°C. The experimental and control groups were tested according to the "Determination of Water Vapor Transmission Performance of Plastic Films and Sheets - Cup Method for Weight Gain and Weight Loss" (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). The water vapor transmission rate and oxygen transmission rate were recorded in Table 1.

[0042] Table 1

[0043]

[0044] As shown in Table 1, the biodegradable materials prepared in Examples 1 to 4 have excellent water vapor and oxygen barrier capabilities, with Example 4 exhibiting the best water vapor and oxygen barrier capabilities, making it worthy of widespread use.

[0045] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

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

2. The biodegradable material based on medium- and long-chain polyhydroxyalkanoates according to claim 1, characterized in that: The bamboo-based lignocellulose has a particle size of 40-60 mesh and is composed of moso bamboo green fragments and moso bamboo yellow fragments in a mass ratio of (1-3):

1.

3. The biodegradable material based on medium- and long-chain polyhydroxy fatty acid esters according to claim 1, characterized in that: The PHAMCL was isolated from a fermentation culture of Pseudomonas mendoza, with the preservation number of Pseudomonas mendoza being CCTCC KB 20082656; The steps to obtain PHAMCL include: inoculating Pseudomonas mendoza into a culture medium, culturing at 120 rpm and 30°C for 48 h, collecting the cells by centrifugation after fermentation, washing with sterile water, freeze-drying, refluxing in an 80°C water bath for 12 h with chloroform as the extraction solution, concentrating the reflux solution, precipitating with cold methanol overnight, and obtaining a white precipitate, which is PHAMCL.

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

5. The biodegradable material based on medium- and long-chain polyhydroxyalkanoates according to claim 1, characterized in that: The thickness ratio of the lignocellulose / PHA membrane to the biodegradable CPP film is (10-50):

1. The biodegradable CPP film comprises the following components by mass: 100 parts PP homopolymer, 18 parts PLA resin, 4 parts PEGT / PBT-based polyether ester, 1 part erucamide and 0.7 parts glyceryl stearate.

6. A method for preparing a biodegradable material based on medium- and long-chain polyhydroxyalkanoates as described in any one of claims 1 to 5, characterized in that: Includes the following steps: S1. Heating and blending: Mix bamboo-based lignocellulose, PHAMCL, polyvinyl alcohol resin, toluene peroxide, sodium persulfate, ethylene glycol, ethanol and deionized water, stir and heat to 70-76℃, keep warm for 30-90 min to obtain a suspension. S2. High-pressure homogenization: First, the suspension is put into a high-pressure fluid nano-homogenizer and homogenized continuously 1 to 2 times at 241.32 to 275.79 MPa. Then, sodium polyacrylate is put into the high-pressure fluid nano-homogenizer and homogenized continuously 4 to 5 times at 137.90 to 206.84 MPa. After dehydration and drying, a mixture is obtained. S3. Extrusion and Casting: PP homopolymer, PLA resin, PEGT / PBT-based polyether ester, erucamide, and glyceryl stearate are added to the first and second extruders respectively. The temperatures of the first and second extruders are set to 140–190°C and the rotation speed is set to 30–60 rpm. After melting and plasticizing, biodegradable CPP resin is obtained. The mixture is added to the third extruder. The temperature of the third extruder is set to 155–200°C and the rotation speed is set to 20–70 rpm. After melting and plasticizing, lignocellulose / PHA resin is obtained. The two groups of biodegradable CPP resin are located on the upper and lower sides of the lignocellulose / PHA resin respectively and are cast through a co-extrusion die. The forming temperature of the co-extrusion die is controlled at 170–190°C to obtain the biodegradable material.

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