Preparation method of high-toughness degradable bio-based film

Abstract

The invention discloses a preparation method of a high-toughness degradable bio-based film, which comprises the following steps: 1, dissolving woody grease, 2, 5-furandimethanol, diisocyanate and a catalyst in a good solvent according to a certain molar ratio, and reacting at 60-80 DEG C for 6-9 hours to prepare a precursor 1 containing a furan ring; and 2, dissolving the precursor 1 containing the furan ring and the maleimide modified cellulose in a good solvent according to a certain mass ratio, then pouring the solution into a mold, and after the solvent is volatilized, reacting at 30-50 DEG C for 6-12 hours to prepare the high-toughness degradable bio-based film. The bio-based film disclosed by the invention has the advantages of green and sustainable raw materials, high toughness and degradability, and can be applied to the fields of agricultural mulching films and the like.

Description

Technical Field

[0001] The present invention relates to a method for preparing a high-strength, tough and degradable bio-based film. Background Art

[0002] With the growth of the global population and the development of agricultural intensification, the annual consumption of agricultural mulch films has exceeded one million tons, which plays an important role in soil heat preservation, water retention and weed control. However, the current mainstream mulch films are still mainly made of petroleum-based polyethylene (PE) materials. Their non-degradable characteristics lead to a large amount of waste mulch films remaining in the soil, forming microplastic pollution, destroying the soil microbial community structure, and entering the human food system through crop absorption, threatening ecological safety and human health. Although starch-based, polylactic acid (PLA) and other degradable mulch films have been gradually promoted, problems such as high brittleness, poor weather resistance, and uncontrollable degradation period still restrict their large-scale application. There is an urgent need to develop a new type of bio-based film with both high mechanical properties and controllable degradability.

[0003] As a natural renewable resource with important application potential, woody oil contains rich hydroxyl and long-chain fatty acid structures in its molecules. It can be used to prepare bio-based polyols or polyurethane polymers through reactions such as esterification, epoxidation, and isocyanate chemistry, and is one of the ideal raw materials to replace petroleum-derived monomers. However, pure woody oil-based polymers often have low mechanical strength due to insufficient crosslinking density, and it is difficult to meet the stringent requirements of complex field application scenarios such as agricultural mulch films and degradable packaging for material weather resistance, creep resistance and other properties. In addition, the highly stable chemical bonds in its structure make it difficult to degrade. To address the above technical bottlenecks, many researchers have focused on cellulose modification research. As the most abundant natural polymer in nature, cellulose has high crystallinity, biocompatibility and degradability, and is an ideal reinforcing filler to improve the mechanical properties of bio-based materials. The abundant hydroxyl groups on its surface are conducive to introducing dynamic covalent bonds through chemical modification, constructing a dynamic covalent crosslinking network with an elastomeric matrix, and improving the mechanical properties of the polymer. At the same time, the reversible characteristics and weak bond energy of dynamic covalent bonds itself improve the degradation performance of bio-based materials.

[0004] This patent innovatively proposes a method for preparing a high-strength, tough and degradable bio-based film based on a dynamic covalent crosslinking network, aiming to develop a green, sustainable, high-strength, tough and degradable bio-based film that can meet the stringent use requirements of agriculture. Summary of the Invention

[0005] Object of the Invention: One of the objects of the present invention is to provide a method for preparing a high-strength, tough and biodegradable bio-based film. This high-strength, tough and biodegradable bio-based film not only has excellent mechanical properties but also exhibits excellent biodegradability, realizing the high-value utilization of polymers while promoting the development of the "dual-carbon strategy". Another object of the present invention is to provide a method for preparing a high-strength, tough and biodegradable bio-based film, which has the characteristics of simple and rapid operation and good repeatability.

[0006] Technical Solution: A high-strength, tough and biodegradable bio-based film described in the present invention has the following general structural formula:

[0007]

[0008] Wherein, R is the characteristic functional group of microcrystalline cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, which is any one of H or -CH3, -CH2CH3, -CH2CH2OH, -CH2CH2CH2OH, -CH2COOH; R1 is the characteristic structure of castor oil, palm oil, hydroxylated epoxidized soybean oil; R2 is the structural unit of diisocyanate.

[0009] The present invention also provides a method for preparing a high-strength, tough and biodegradable bio-based film, and the steps are as follows:

[0010] (1) Dissolve woody oil, 2,5-furandimethanol, diisocyanate and catalyst in a good solvent according to a certain molar ratio and react at 60 - 80 °C for 6 - 9 h to prepare a furan ring-containing precursor 1;

[0011] (2) Dissolve the furan ring-containing precursor 1 and maleimide-modified cellulose in a good solvent according to a certain mass ratio, pour it into a mold, and react at 30 - 50 °C for 6 - 12 h after the solvent volatilizes to prepare a high-strength, tough and biodegradable bio-based film.

[0012] In the above step (1), the molar ratio of woody oil, 2,5-furandimethanol, diisocyanate and catalyst is [woody oil]:[2,5-furandimethanol]:[diisocyanate]:[catalyst] = 1 - 1.50:1:1.5 - 2:0.003 - 0.006.

[0013] Among them, the woody oil is any one of castor oil, palm oil, and hydroxylated epoxy soybean oil; the diisocyanate is any one of 2,4-diphenylmethane diisocyanate, toluene-2,4-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and p-phenylene diisocyanate; the catalyst is any one of stannous octoate, dibutyltin dilaurate, triethylenediamine, tetramethylbutanediamine, triethylenediamine, and tetramethylbutanediamine; the good solvent is any one of N,N-dimethylformamide, dimethyl sulfoxide, toluene, and tetrahydrofuran.

[0014] In the above step (2), the mass ratio of the furan ring-containing precursor 1 to the maleimide-modified cellulose is [furan ring-containing precursor 1]:[maleimide-modified cellulose]=1:0.025-0.075.

[0015] Among them, the maleimide-modified cellulose is any one of maleimide-modified methyl cellulose, maleimide-modified ethyl cellulose, maleimide-modified hydroxyethyl cellulose, maleimide-modified hydroxypropyl cellulose, maleimide-modified carboxymethyl cellulose, and maleimide-modified microcrystalline cellulose; the good solvent is any one of N,N-dimethylformamide, dimethyl sulfoxide, toluene, and tetrahydrofuran.

[0016] Beneficial effects:

[0017] (1) The preparation method of the high-strength, tough and degradable bio-based film involved in the present invention has the characteristics of simple preparation and good repeatability.

[0018] (2) The high-strength, tough and degradable bio-based film involved in the present invention can be used as a new type of bio-based film for farmland. In addition to having excellent mechanical properties, it can be degraded by about 90% within 70 days through soil burial, meeting the requirements of the green development strategy and being applicable to a wider range of applications. Description of the drawings

[0019] Figure 1 It is the uniaxial tensile stress-strain curve of the high-strength, tough and degradable bio-based film in Example 1.

[0020] Figure 2 It is the curve of the residual mass of the high-strength, tough and degradable bio-based film in Example 1 and the soil burial time. Detailed implementation manners

[0021] The present invention will be further described in detail below with reference to examples.

[0022] The raw materials and reagents in the following examples are all commercially available.

[0023] Example 1: Preparation of a high-strength, tough and degradable bio-based film using ethyl cellulose

[0024] First step: Castor oil, 2,5-furandimethanol, 2,4-diphenylmethane diisocyanate, and dibutyltin dilaurate were dissolved in tetrahydrofuran at a molar ratio of [castor oil]:[2,5-furandimethanol]:[2,4-diphenylmethane diisocyanate]:[dibutyltin dilaurate]=1.30:1:1.80:0.006 and reacted at 70 °C for 7 h to prepare precursor 1.

[0025] Second step: The furan ring-containing precursor 1 and maleimide-modified ethyl cellulose were dissolved in tetrahydrofuran at a mass ratio of [furan ring-containing precursor 1]:[maleimide-modified ethyl cellulose]=1:0.05 and heated at 40 °C for 12 h to prepare a high-strength, tough, and degradable bio-based film.

[0026] Figure 1 For the tensile stress-strain curve of the high-strength, tough, and degradable bio-based film in Example 1, it can be seen from the figure that the tensile strength of the bio-based film can reach 25.61 MPa and the toughness is 43.45 MJ / m 3 .

[0027] Figure 2 For the graph of the soil burial time and residual mass of the high-strength, tough, and degradable bio-based film in Example 1, it can be seen from the figure that after 70 days of soil burial, the residual mass of the bio-based film can be reduced to less than 10%.

[0028] Example 2: Preparation of a high-strength, tough, and degradable bio-based film using methyl cellulose

[0029] First step: Castor oil, 2,5-furandimethanol, hexamethylene diisocyanate, and dibutyltin dilaurate were dissolved in toluene at a molar ratio of [castor oil]:[2,5-furandimethanol]:[2,4-diphenylmethane diisocyanate]:[dibutyltin dilaurate]=1.40:1:1.90:0.005 and reacted at 60 °C for 9 h to prepare precursor 1.

[0030] Second step: The furan ring-containing precursor 1 and maleimide-modified methyl cellulose were dissolved in toluene at a mass ratio of [furan ring-containing precursor 1]:[maleimide-modified methyl cellulose]=1:0.025 and heated at 50 °C for 9 h to prepare a high-strength, tough, and degradable bio-based film.

[0031] Example 3: Preparation of a high-strength, tough, and degradable bio-based film using hydroxyethyl cellulose

[0032] First step: Dissolve palm oil, 2,5-furandimethanol, isophorone diisocyanate, and stannous octoate in dimethyl sulfoxide according to the molar ratio of [palm oil]:[2,5-furandimethanol]:[isophorone diisocyanate]:[stannous octoate] = 1.40:1:1.90:0.006, and react at 70 °C for 9 h to prepare precursor 1;

[0033] Second step: Dissolve precursor 1 containing a furan ring and maleimide-modified hydroxyethyl cellulose in dimethyl sulfoxide according to the mass ratio of [precursor 1 containing a furan ring]:[maleimide-modified hydroxyethyl cellulose] = 1:0.075, and heat at 30 °C for 12 h to prepare a high-strength, tough, and degradable bio-based film.

[0034] Example 4: Preparation of a high-strength, tough, and degradable bio-based film using hydroxypropyl cellulose

[0035] First step: Dissolve hydroxylated epoxidized soybean oil, 2,5-furandimethanol, p-phenylene diisocyanate, and triethylenediamine in toluene according to the molar ratio of [hydroxylated epoxidized soybean oil]:[2,5-furandimethanol]:[p-phenylene diisocyanate]:[triethylenediamine] = 1.20:1:1.60:0.006, and react at 60 °C for 9 h to prepare precursor 1;

[0036] Second step: Dissolve precursor 1 containing a furan ring and maleimide-modified hydroxypropyl cellulose in toluene according to the mass ratio of [precursor 1 containing a furan ring]:[maleimide-modified hydroxypropyl cellulose] = 1:0.075, and heat at 30 °C for 12 h to prepare a high-strength, tough, and degradable bio-based film.

[0037] Example 5: Preparation of a high-strength, tough, and degradable bio-based film using carboxymethyl cellulose

[0038] First step: Dissolve hydroxylated epoxidized soybean oil, 2,5-furandimethanol, dicyclohexylmethane diisocyanate, and dibutyltin dilaurate in dimethyl sulfoxide according to the molar ratio of [hydroxylated epoxidized soybean oil]:[2,5-furandimethanol]:[dicyclohexylmethane diisocyanate]:[dibutyltin dilaurate] = 1.20:1:1.60:0.004, and react at 70 °C for 8 h to prepare precursor 1;

[0039] Second step: Dissolve precursor 1 containing a furan ring and maleimide-modified carboxymethyl cellulose in dimethyl sulfoxide according to the mass ratio of [precursor 1 containing a furan ring]:[maleimide-modified carboxymethyl cellulose] = 1:0.05, and heat at 40 °C for 9 h to prepare a high-strength, tough, and degradable bio-based film.

[0040] Example 6: Preparation of a high-strength, tough, and degradable bio-based film using microcrystalline cellulose

[0041] First step: Castor oil, 2,5-furandimethanol, dicyclohexylmethane diisocyanate, and dibutyltin dilaurate were dissolved in N,N-dimethylformamide at a molar ratio of [castor oil]:[2,5-furandimethanol]:[dicyclohexylmethane diisocyanate]:[dibutyltin dilaurate] = 1.20:1:1.60:0.004 and reacted at 70 °C for 8 h to prepare precursor 1;

[0042] Second step: The furan ring-containing precursor 1 and maleimide-modified carboxymethyl cellulose were dissolved in N,N-dimethylformamide at a mass ratio of [furan ring-containing precursor 1]:[maleimide-modified carboxymethyl cellulose] = 1:0.05 and heated at 40 °C for 9 h to prepare a high-strength, tough, and degradable bio-based film.

[0043] Tests found that the high-strength, tough, and degradable bio-based films prepared in Examples 1-6 above had high strength and high toughness. At the same time, the discarded bio-based films could be almost completely degraded within 70 days by soil burial, demonstrating the green application potential of bio-based films in the field of agricultural mulch films and promoting the green development of the dual-carbon strategy.

Claims

1. A preparation method of a high-strength, tough and degradable bio-based film, characterized in that The general structural formula is as follows Among them, R is the characteristic functional group of microcrystalline cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and carboxymethyl cellulose, which is any one of H or -CH3, -CH2CH3, -CH2CH2OH, -CH2CH2CH2OH, -CH2COOH; R1 is the characteristic structure of castor oil, palm oil, hydroxylated epoxy soybean oil, or hydroxylated coriander fruit oil; R2 is the structural unit of diisocyanate.

2. A preparation method of a high-strength, tough and degradable bio-based film, characterized in that It includes the following steps (1) Dissolve woody oil, 2,5-furandimethanol, diisocyanate, and catalyst in a good solvent at a certain molar ratio and react at 60 - 80 °C for 6 - 9 h to prepare precursor 1 containing a furan ring; the molar ratio of the woody oil, 2,5-furandimethanol, diisocyanate, and catalyst is woody oil:2,5-furandimethanol:diisocyanate:catalyst = 1 - 1.50:1:1.5 - 2:0.003 - 0.

006. The woody oil is any one of castor oil, palm oil, and hydroxylated epoxy soybean oil; the diisocyanate is any one of 2,4-diphenylmethane diisocyanate, toluene-2,4-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and p-phenylene diisocyanate; the catalyst is any one of stannous octoate, dibutyltin dilaurate, triethylenediamine, tetramethylbutanediamine, triethylenediamine, and tetramethylbutanediamine; the good solvent is any one of N,N-dimethylformamide, dimethyl sulfoxide, toluene, and tetrahydrofuran. (2) Dissolve precursor 1 containing a furan ring and maleimide-modified cellulose in a good solvent at a certain mass ratio, pour it into a mold, and react at 30 - 50 °C for 6 - 12 h after the solvent evaporates to prepare a high-strength, tough, and degradable bio-based film. The mass ratio of precursor 1 containing a furan ring to maleimide-modified cellulose is precursor 1 containing a furan ring:maleimide-modified cellulose = 1:0.025 - 0.

075. The maleimide-modified cellulose is any one of maleimide-modified methyl cellulose, maleimide-modified ethyl cellulose, maleimide-modified hydroxyethyl cellulose, maleimide-modified hydroxypropyl cellulose, maleimide-modified carboxymethyl cellulose, and maleimide-modified microcrystalline cellulose; the good solvent is any one of N,N-dimethylformamide, dimethyl sulfoxide, toluene, and tetrahydrofuran.

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