Full-biodegradable bamboo fiber film material and preparation method thereof

Abstract

The invention relates to the technical field of biodegradable materials, and discloses a full-biodegradable bamboo fiber film material and a preparation method thereof, the full-biodegradable bamboo fiber film material comprises the following raw materials by weight: 30-50 parts of modified bamboo fiber, 20-40 parts of a biodegradable polymer, 3-8 parts of a plasticizer, and 1-5 parts of a cross-linking agent. Acrylic acid grafted hydroxyethyl methylacrylate is grafted to epoxy resin containing azobenzene side chains to form a grafting product of a latticed structure, and the grafting product and hydroxyl groups on bamboo fibers form ether bonds to modify the bamboo fibers. The latticed structure can effectively improve the mechanical property of the film, and azobenzene is grafted to the side chain of bisphenol A epoxy resin, so that the epoxy resin has better degradability.

Description

Technical Field

[0001] The present invention relates to the technical field of biodegradable materials, and particularly to a fully biodegradable bamboo fiber film material and a preparation method thereof. Background Art

[0002] Traditional plastic films are difficult to degrade, causing serious environmental pollution. Although existing biodegradable materials (such as polylactic acid PLA and polybutylene succinate PBS) can be degraded, they have problems such as high cost, insufficient mechanical properties, and harsh degradation conditions. Bamboo fiber, as a natural renewable resource, has a high cellulose content and excellent mechanical properties, but it is brittle and has poor barrier properties when formed into a film alone. In the prior art, when bamboo fiber is compounded with other polymers, the performance is often unstable due to poor interfacial compatibility. Therefore, there is an urgent need for a bamboo fiber film material with low cost, high performance, and complete biodegradability. Summary of the Invention

[0003] (1) Technical Problems to be Solved

[0004] In view of the deficiencies of the prior art, the present invention provides a fully biodegradable bamboo fiber film material and a preparation method thereof.

[0005] (2) Technical Solutions

[0006] To achieve the above object, the present invention provides the following technical solutions: A fully biodegradable bamboo fiber film material, which is composed of the following raw materials in parts by weight:

[0007] 30 - 50 parts of modified bamboo fiber, 20 - 40 parts of biodegradable polymer, 3 - 8 parts of plasticizer, and 1 - 5 parts of crosslinking agent.

[0008] Preferably, the preparation method of the modified bamboo fiber is as follows:

[0009] S1. Select healthy moso bamboo aged 3 - 5 years, remove the diseased and pest - infested parts, cut it into small sections of 3 - 5 cm, wash and dry it, crush it into bamboo chips with a particle size of 1 - 3 mm using a crusher, and use the steam explosion method with a pressure of 1.5 - 2.0 MPa and a pressure - holding time of 3 - 5 min to separate the bamboo fiber;

[0010] S2. Add hydroxyethyl methacrylate to deionized water, stir evenly, pass nitrogen, heat up to 60 - 80 °C, add the initiator potassium persulfate, slowly dropwise add acrylic acid monomer, add the crosslinking agent N,N’ - methylenebisacrylamide, and react for 2 - 5 h to obtain acrylic acid - grafted hydroxyethyl methacrylate;

[0011] S3. Under ice bath conditions, dissolve aniline in hydrochloric acid, slowly add an aqueous solution of sodium nitrite dropwise to obtain a diazonium salt; dissolve phenol in a 2 mol / L sodium hydroxide solution, slowly add the diazonium salt, adjust the pH to 8 - 9, stir and react for 1 - 5 h, filter to obtain a precipitate, dissolve the precipitate in tetrahydrofuran, add lithium aluminum hydride, reflux and react for 3 - 8 h, filter, and recrystallize with ethanol to obtain 4 - aminoazobenzene;

[0012] S4. Dissolve bisphenol A epoxy resin in acetone, add 4 - aminoazobenzene, dropwise add triethylamine, heat up to reflux and stir for 5 - 10 h, pour it into methanol to precipitate, filter, wash and dry to obtain an epoxy resin containing an azobenzene side chain;

[0013] S5. Add hydroxyethyl methacrylate to dichloromethane, add N,N - dimethylformamide, and react for 2 - 5 h to obtain methacryloyl chloride; add the epoxy resin containing an azobenzene side chain, methacryloyl chloride, and triethylamine to toluene, stir and react for 2 - 6 h, add acrylic acid - grafted hydroxyethyl methacrylate and azobisisobutyronitrile to the reaction system, heat up to reflux, and stir and react for 6 - 10 h to obtain a network - shaped epoxy resin grafted product containing an azobenzene side chain;

[0014] S6. Immerse bamboo fibers in a sodium hydroxide solution with a mass fraction of 5 - 10%, stir at 60 - 80 °C for 30 - 60 min, wash with water until neutral, add to the network - shaped epoxy resin grafted product containing an azobenzene side chain and stir evenly, add the cross - linker glutaraldehyde and the initiator potassium persulfate, heat up to 60 - 80 °C and react for 2 - 6 h to obtain modified bamboo fibers.

[0015] Preferably, in step S2, the mass ratio of hydroxyethyl methacrylate, initiator potassium persulfate, acrylic acid monomer, and cross - linker N,N’ - methylenebisacrylamide is 1:0.01 - 0.03:0.3 - 0.5:0.01 - 0.03.

[0016] Preferably, in step S3, the mass ratio of aniline, sodium nitrite, phenol, and lithium aluminum hydride is 1:0.7 - 0.9:1.1 - 1.3:0.3 - 0.6.

[0017] Preferably, in step S4, the mass ratio of bisphenol A epoxy resin, 4 - aminoazobenzene, and triethylamine is 100:3 - 8:0.1 - 0.3.

[0018] Preferably, in step S5, the mass ratio of hydroxyethyl methacrylate, dichloromethane, epoxy resin containing an azobenzene side chain, triethylamine, acrylic acid - grafted hydroxyethyl methacrylate, and azobisisobutyronitrile is 1:1.5 - 3:5 - 8:0.05 - 0.08:0.8 - 1.2:0.1 - 0.3.

[0019] Preferably, in step S6, the mass ratio of bamboo fiber, epoxy resin grafting product with grid-like azobenzene side chain, cross-linking agent glutaraldehyde, and initiator potassium persulfate is 1: 0.5-2: 0.05-0.1: 0.01-0.05.

[0020] Preferably, the biodegradable polymer is one of PLA, PBS, and PBAT.

[0021] Preferably, the plasticizer is one of glycerol, citrate ester, and polyethylene glycol.

[0022] Preferably, the cross-linking agent is one of epoxidized soybean oil, epoxidized lignin, or epoxidized tannic acid.

[0023] Preferably, the preparation method is as follows: Put the modified bamboo fiber, biodegradable polymer, plasticizer, and cross-linking agent into a high-speed mixer, stir at a speed of 500-800 rpm for 5-10 minutes, extrude with a twin-screw extruder, set the temperature to 140-180 °C, and blow with a blown film machine, set the temperature to 150-180 °C.

[0024] (III) Beneficial technical effects

[0025] Hydroxyethyl methacrylate and acrylic acid monomer undergo esterification of hydroxyl and carboxyl groups to obtain acrylic acid grafted hydroxyethyl methacrylate; 4-aminoazobenzene is grafted onto bisphenol A epoxy resin, and the amino group and epoxy group undergo ring-opening addition reaction to produce a hydroxy side chain containing azobenzene. Through the initiation of a free radical initiator, an acyl chloride group is introduced onto the side chain hydroxyl, and then grafted with acrylic acid grafted hydroxyethyl methacrylate containing a double bond to form a grafting product with a grid-like structure, which forms an ether bond with the hydroxyl group on the bamboo fiber to modify the bamboo fiber. The grid-like structure can effectively improve the mechanical properties of the film, and by grafting azobenzene onto the side chain of bisphenol A epoxy resin, the epoxy resin can have better degradability. Specific embodiments

[0026] The parts in the examples are all parts by weight.

[0027] Example 1

[0028] The preparation method of the modified bamboo fiber is as follows:

[0029] S1. Select healthy moso bamboo aged 3-5 years, remove the pest and disease parts, cut it into 3 cm small sections, wash and dry it, crush it into bamboo chips with a particle size of 1-3 mm with a crusher, and use the steam explosion method with a pressure of 1.5 MPa and a pressure holding time of 3 minutes to separate the bamboo fiber.

[0030] S2. Add 30 parts of 2-hydroxyethyl methacrylate to 100 parts of deionized water, stir evenly, pass nitrogen, heat up to 60 °C, add 0.3 part of initiator potassium persulfate, slowly dropwise add 9 parts of acrylic acid monomer, add 0.3 part of crosslinking agent N,N'-methylenebisacrylamide, react for 2 h to obtain acrylic acid grafted 2-hydroxyethyl methacrylate.

[0031] S3. Under ice bath conditions, dissolve 10 parts of aniline in hydrochloric acid, slowly dropwise add 20 parts of aqueous sodium nitrite solution to prepare a diazonium salt; dissolve 11 parts of phenol in 2 mol / L sodium hydroxide solution, slowly add the diazonium salt, adjust the pH to 8, stir and react for 1 h, filter to obtain a precipitate, dissolve the precipitate in tetrahydrofuran, add 3 parts of lithium aluminum hydroxide, reflux and react for 3 h, filter, and recrystallize with ethanol to obtain 4-aminoazobenzene.

[0032] S4. Dissolve 100 parts of bisphenol A epoxy resin in acetone, add 3 parts of 4-aminoazobenzene, dropwise add 0.1 part of triethylamine, heat up to reflux and stir for 5 h, pour into methanol to precipitate, filter, wash and dry to obtain an epoxy resin containing an azobenzene side chain.

[0033] S5. Add 20 parts of 2-hydroxyethyl methacrylate to 30 parts of dichloromethane, add 80 parts of N,N-dimethylformamide, react for 2 h to obtain methacryloyl chloride; add 100 parts of epoxy resin containing an azobenzene side chain, methacryloyl chloride, and 1 part of triethylamine to toluene, stir and react for 2 h, add 16 parts of acrylic acid grafted 2-hydroxyethyl methacrylate and 2 parts of azobisisobutyronitrile to the reaction system, heat up to reflux, stir and react for 6 h to obtain a network-shaped epoxy resin grafted product containing an azobenzene side chain.

[0034] S6. Immerse 50 parts of bamboo fiber in a 5% sodium hydroxide solution by mass, stir at 60 °C for 30 min, wash with water until neutral, add to 25 parts of the network-shaped epoxy resin grafted product containing an azobenzene side chain and stir evenly, add 2.5 parts of crosslinking agent glutaraldehyde and 0.5 part of initiator potassium persulfate, heat up to 60 °C and react for 2 h to obtain modified bamboo fiber.

[0035] The preparation method of the fully biodegradable bamboo fiber film material is as follows:

[0036] Put 30 parts of modified bamboo fiber, 20 parts of biodegradable polymer, 3 parts of plasticizer, and 1 part of crosslinking agent into a high-speed mixer, stir at 500 rpm for 5 min, extrude with a twin-screw extruder, set the temperature to 140 °C, and blow with a blown film machine, set the temperature to 150 °C.

[0037] Example 2

[0038] The preparation method of the modified bamboo fiber is as follows:

[0039] S1. Select healthy moso bamboos aged 3 - 5 years, remove the parts damaged by pests and diseases, cut them into 4 - cm small sections, wash with water and dry, crush them into bamboo chips with a particle size of 1 - 3 mm using a pulverizer, and use the steam explosion method with a pressure of 1.8 MPa and a pressure - holding time of 4 min to separate bamboo fibers.

[0040] S2. Add 30 parts of hydroxyethyl methacrylate to 125 parts of deionized water, stir evenly, pass nitrogen, heat up to 70 °C, add 0.6 part of initiator potassium persulfate, slowly drop - wise add 12 parts of acrylic acid monomer, add 0.6 part of cross - linker N,N’ - methylenebisacrylamide, and react for 3 h to obtain acrylic - grafted hydroxyethyl methacrylate.

[0041] S3. Under ice - bath conditions, dissolve 10 parts of aniline in hydrochloric acid, slowly drop - wise add 25 parts of sodium nitrite aqueous solution to prepare a diazonium salt; dissolve 12 parts of phenol in 2 mol / L sodium hydroxide solution, slowly add the diazonium salt, adjust the pH to 9, stir and react for 3 h, filter to obtain a precipitate, dissolve the precipitate in tetrahydrofuran, add 4 parts of lithium aluminum hydroxide, reflux and react for 6 h, filter, and recrystallize with ethanol to obtain 4 - aminoazobenzene.

[0042] S4. Dissolve 100 parts of bisphenol A epoxy resin in acetone, add 5 parts of 4 - aminoazobenzene, drop - wise add 0.2 part of triethylamine, heat up to reflux and stir for 7 h, pour it into methanol to precipitate, filter, wash and dry to obtain an epoxy resin containing an azobenzene side chain.

[0043] S5. Add 20 parts of hydroxyethyl methacrylate to 45 parts of dichloromethane, add 120 parts of N,N - dimethylformamide, and react for 3 h to obtain methacryloyl chloride; add 100 parts of epoxy resin containing an azobenzene side chain, methacryloyl chloride, and 1.2 parts of triethylamine to toluene, stir and react for 4 h, add 20 parts of acrylic - grafted hydroxyethyl methacrylate and 3 parts of azobisisobutyronitrile to the reaction system, heat up to reflux, and stir and react for 8 h to obtain a grid - shaped epoxy resin grafted product containing an azobenzene side chain.

[0044] S6. Immerse 50 parts of bamboo fibers in a 7% sodium hydroxide solution by mass, stir at 70 °C for 45 min, wash with water until neutral, add them to 60 parts of the grid - shaped epoxy resin grafted product containing an azobenzene side chain and stir evenly, add 4 parts of cross - linker glutaraldehyde and 1.5 parts of initiator potassium persulfate, heat up to 70 °C and react for 4 h to obtain modified bamboo fibers.

[0045] The preparation method of the fully biodegradable bamboo fiber film material is as follows:

[0046] Put 40 parts of modified bamboo fibers, 30 parts of biodegradable polymer, 5 parts of plasticizer, and 3 parts of cross - linker into a high - speed mixer, stir at 600 rpm for 10 min, extrude with a twin - screw extruder, set the temperature to 160 °C, and blow with a blown - film machine, set the temperature to 160 °C.

[0047] Example 3

[0048] The preparation method of the modified bamboo fiber is as follows:

[0049] S1. Select healthy moso bamboo aged 3 - 5 years, remove the parts damaged by pests and diseases, cut it into small sections of 5 cm, wash and dry it with water, crush it into bamboo chips with a particle size of 1 - 3 mm by a pulverizer, and use the steam explosion method with a pressure of 2.0 MPa and a pressure - holding time of 5 min to separate the bamboo fiber.

[0050] S2. Add 30 parts of hydroxyethyl methacrylate to 150 parts of deionized water, stir evenly, pass nitrogen, heat up to 80 °C, add 0.9 part of initiator potassium persulfate, slowly drop - add 15 parts of acrylic acid monomer, add 0.9 part of cross - linker N,N’ - methylenebisacrylamide, and react for 5 h to obtain acrylic acid grafted hydroxyethyl methacrylate.

[0051] S3. Under ice - bath conditions, dissolve 10 parts of aniline in hydrochloric acid, slowly drop - add 30 parts of sodium nitrite aqueous solution to prepare a diazonium salt; dissolve 13 parts of phenol in 2 mol / L sodium hydroxide solution, slowly add the diazonium salt, adjust the pH to 9, stir and react for 5 h, filter to obtain a precipitate, dissolve the precipitate in tetrahydrofuran, add 6 parts of lithium aluminum hydroxide, reflux and react for 8 h, filter, and recrystallize with ethanol to obtain 4 - aminoazobenzene.

[0052] S4. Dissolve 100 parts of bisphenol A epoxy resin in acetone, add 8 parts of 4 - aminoazobenzene, drop - add 0.3 part of triethylamine, heat up to reflux and stir for 10 h, pour it into methanol to precipitate, filter, wash and dry to obtain an epoxy resin containing an azobenzene side chain.

[0053] S5. Add 20 parts of hydroxyethyl methacrylate to 60 parts of dichloromethane, add 160 parts of N,N - dimethylformamide, and react for 5 h to obtain methacryloyl chloride; add 100 parts of the epoxy resin containing an azobenzene side chain, methacryloyl chloride, and 1.6 parts of triethylamine to toluene, stir and react for 6 h, add 24 parts of acrylic acid grafted hydroxyethyl methacrylate and 6 parts of azobisisobutyronitrile to the reaction system, heat up to reflux, and stir and react for 10 h to obtain a grid - shaped epoxy resin grafted product containing an azobenzene side chain.

[0054] S6. Immerse 50 parts of bamboo fiber in a 10% sodium hydroxide solution by mass fraction, stir at 80 °C for 60 min, wash with water until neutral, add it to 100 parts of the grid - shaped epoxy resin grafted product containing an azobenzene side chain and stir evenly, add 5 parts of cross - linker glutaraldehyde and 2.5 parts of initiator potassium persulfate, heat up to 80 °C and react for 6 h to obtain the modified bamboo fiber.

[0055] The preparation method of the fully biodegradable bamboo fiber film material is as follows:

[0056] Put 50 parts of modified bamboo fiber, 40 parts of biodegradable polymer, 8 parts of plasticizer, and 5 parts of crosslinking agent into a high-speed mixer, stir at 800 rpm for 10 min, extrude with a twin-screw extruder, set the temperature to 180 °C, and blow film with a film blowing machine, set the temperature to 180 °C.

[0057] Comparative Example 1: Do not perform the steps in S4, conduct a modification experiment with bisphenol A epoxy resin, and the remaining processes are the same as in Example 1.

[0058] Comparative Example 2: Do not modify the bamboo fiber, and the remaining processes are the same as in Example 1.

[0059] Performance test: Make the films with a thickness of 100 μm from Examples 1 to 3 and Comparative Examples 1 and 2, test the biodegradability according to ASTM D 5511-2018, and test the tensile strength. The results are shown in Table 1;

[0060] Table 1

[0061]

[0062]

[0063] As can be seen from Table 1, compared with the examples, the biodegradation rate of Comparative Example 1 is significantly lower than that of the examples, and the tensile strength is slightly lower than that of the examples, indicating that the grafting experiment of the azobenzene side chain of bisphenol A epoxy resin in step S4 can effectively improve the biodegradation rate of epoxy resin. Compared with the examples, the tensile strength of Comparative Example 2 is lower, indicating that the modification of bamboo fiber with the epoxy resin grafting product containing a grid-like azobenzene side chain can significantly improve its mechanical strength.

[0064] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. The fully biodegradable bamboo fiber film material is characterized in that It consists of the following raw materials in parts by weight: 30 - 50 parts of modified bamboo fiber, 20 - 40 parts of biodegradable polymer, 3 - 8 parts of plasticizer, 1 - 5 parts of crosslinking agent.

2. The fully biodegradable bamboo fiber film material according to claim 1, wherein: The preparation method of the modified bamboo fiber is as follows: S1. Select healthy bamboo aged 3 - 5 years, remove the parts damaged by pests and diseases, cut it into small sections of 3 - 5 cm, wash and dry it, crush it into bamboo chips with a particle size of 1 - 3 mm by a crusher, and use the steam explosion method with a pressure of 1.5 - 2.0 MPa and a pressure - holding time of 3 - 5 min to separate the bamboo fiber; S2. Add hydroxyethyl methacrylate into deionized water, stir evenly, pass nitrogen, heat up to 60 - 80 °C, add potassium persulfate as the initiator, slowly dropwise add acrylic acid monomer, add N,N'-methylenebisacrylamide as the crosslinking agent, and react for 2 - 5 h to obtain acrylic acid grafted hydroxyethyl methacrylate; S3. Under ice - bath conditions, dissolve aniline in hydrochloric acid, slowly dropwise add an aqueous solution of sodium nitrite to prepare a diazonium salt; dissolve phenol in 2 mol / L sodium hydroxide solution, slowly add the diazonium salt, adjust the pH to 8 - 9, stir and react for 1 - 5 h, filter to obtain a precipitate, dissolve the precipitate in tetrahydrofuran, add lithium aluminum hydroxide, reflux and react for 3 - 8 h, filter, and recrystallize with ethanol to obtain 4 - aminoazobenzene; S4. Dissolve bisphenol A epoxy resin in acetone, add 4 - aminoazobenzene, dropwise add triethylamine, heat up to reflux and stir for 5 - 10 h, pour it into methanol to precipitate, filter, wash and dry to obtain an epoxy resin containing an azobenzene side chain; S5. Add hydroxyethyl methacrylate into dichloromethane, add N,N - dimethylformamide, and react for 2 - 5 h to obtain methacryloyl chloride; add the epoxy resin containing an azobenzene side chain, methacryloyl chloride, and triethylamine into toluene, stir and react for 2 - 6 h, add acrylic acid grafted hydroxyethyl methacrylate and azobisisobutyronitrile to the reaction system, heat up to reflux, and stir and react for 6 - 10 h to obtain a network - shaped epoxy resin grafted product containing an azobenzene side chain; S6. Immerse the bamboo fiber in a sodium hydroxide solution with a mass fraction of 5 - 10%, stir at 60 - 80 °C for 30 - 60 min, wash with water until neutral, add it to the network - shaped epoxy resin grafted product containing an azobenzene side chain and stir evenly, add glutaraldehyde as the crosslinking agent and potassium persulfate as the initiator, heat up to 60 - 80 °C and react for 2 - 6 h to obtain the modified bamboo fiber.

3. The fully biodegradable bamboo fiber film material according to claim 2, characterized in that: In step S2, the mass ratio of hydroxyethyl methacrylate, potassium persulfate as the initiator, acrylic acid monomer, and N,N'-methylenebisacrylamide as the crosslinking agent is 1:0.01 - 0.03:0.3 - 0.5:0.01 - 0.

03.

4. The fully biodegradable bamboo fiber thin film material according to claim 2, characterized in that: In step S3, the mass ratio of aniline, sodium nitrite, phenol, and lithium aluminum hydroxide is 1:0.7 - 0.9:1.1 - 1.3:0.3 - 0.

6.

5. The fully biodegradable bamboo fiber film material according to claim 2, wherein: In step S4, the mass ratio of bisphenol A epoxy resin, 4 - aminoazobenzene, and triethylamine is 100:3 - 8:0.1 - 0.

3.

6. The fully biodegradable bamboo fiber thin film material according to claim 2, characterized in that: In the step S5, the mass ratio of 2-hydroxyethyl methacrylate, dichloromethane, epoxy resin containing azobenzene side chain, triethylamine, acrylic acid grafted 2-hydroxyethyl methacrylate, and azodiisobutyronitrile is 1: 1.5-3: 5-8: 0.05-0.08: 0.8-1.2: 0.1-0.

3.

7. The fully biodegradable bamboo fiber film material according to claim 2, wherein: In the step S6, the mass ratio of bamboo fiber, epoxy resin grafted product with grid-like azobenzene side chain, cross-linking agent glutaraldehyde, and initiator potassium persulfate is 1: 0.5-2: 0.05-0.1: 0.01-0.

05.

8. The fully biodegradable bamboo fiber film material according to claim 1, characterized in that: The biodegradable polymer is one of PLA, PBS, and PBAT; The plasticizer is one of glycerol, citrate ester, and polyethylene glycol; The cross-linking agent is one of epoxidized soybean oil, epoxidized lignin, or epoxidized tannic acid.

9. The fully biodegradable bamboo fiber film material according to any one of claims 1 to 8, characterized in that, The preparation method is as follows: Put the modified bamboo fiber, biodegradable polymer, plasticizer, and cross-linking agent into a high-speed mixer, stir at a speed of 500-800 rpm for 5-10 minutes, extrude with a twin-screw extruder, set the temperature to 140-180 °C, and blow with a blown film machine, set the temperature to 150-180 °C.

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