CN-116589722-B - High-strength high-light-transmittance bio-based polyurethane film and preparation method thereof

Abstract

The invention belongs to the field of bio-based functional polymer materials, and particularly relates to a high-strength high-light-transmittance bio-based polyurethane film and a preparation method thereof. The invention prepares malic acid polyol by utilizing the reaction of malic acid and aromatic ring dihydric alcohol, then carries out polymerization reaction with isocyanate, uses a small molecule chain extender to carry out chain extension, and ends-capped coumarin derivative monomer to prepare the bio-based polyurethane. And then a casting method and ice bath cooling treatment are adopted to obtain the bio-based polyurethane film which has high light transmittance, good mechanical property and biodegradability. The invention belongs to a renewable material of biological base source, and has potential application prospect in the fields of crop mulching films, packaging materials and the like.

Inventors

• WANG YANNING
• LI RUIDONG
• LI NING
• ZHANG XIAOYU
• LIN WENBO
• CHEN SHENGNAN
• Tong Xinlin
• LI JINCHUN
• SUN XIAOYU
• LIU YIXUAN

Assignees

• 常州大学

Dates

Publication Date

20260505

Application Date

20230609

Claims (7)

1. 1. The preparation method of the high-strength high-light-transmittance bio-based polyurethane film is characterized by comprising the following steps of: (1) Uniformly mixing malic acid with aromatic ring dihydric alcohol, adding a catalyst dissolved in an organic solvent, reacting under the protection of 130-140℃, N 2 until the acid value is reduced to 1mg KOH/g, stopping the reaction, and cooling to obtain malic acid polyhydric alcohol, wherein the aromatic ring dihydric alcohol is any one of 1, 4-benzenediol, hydroquinone bishydroxyethyl ether, resorcinol bishydroxyethyl ether or bisphenol A, and the molar ratio of the malic acid to the aromatic ring dihydric alcohol is 1:2; (2) Dehydrating malic acid polyol, mixing the dehydrated malic acid polyol with isocyanate and an organotin catalyst, dissolving the mixture in an organic solvent, reacting for 2 hours at 75-85 ℃ to obtain an isocyanato-terminated bio-based polyurethane prepolymer, dissolving the bio-based polyurethane prepolymer and a small molecular chain extender in the organic solvent, and reacting for 1 hour at 35-45 ℃ to obtain isocyanato-terminated bio-based polyurethane, wherein the molar ratio of the malic acid polyol to the isocyanate is 3:1, and the molar ratio of the small molecular chain extender to the malic acid polyol is 1.5:1; (3) Dissolving coumarin derivative monomer and bio-based polyurethane prepared in the step (2) in an organic solvent, reacting for 1h at 35-45 ℃ to obtain the bio-based polyurethane capped by the coumarin derivative monomer, dissolving the bio-based polyurethane capped by the coumarin derivative monomer in the organic solvent, pouring the bio-based polyurethane into a polytetrafluoroethylene plate, placing the polytetrafluoroethylene plate into a baking oven, drying at 80 ℃ for 24-48h, placing the polytetrafluoroethylene plate into an ice bath, and cooling for 30min to obtain the high-strength high-light-transmittance bio-based polyurethane film, wherein the coumarin derivative monomer is any one of 7-hydroxycoumarin or 4-methylumbelliferone, and the molar ratio of the coumarin derivative monomer to malic acid polyol is 3:1.
2. 2. The method for preparing a high-strength high-light-transmittance bio-based polyurethane film according to claim 1, wherein the catalyst in the step (1) is any one of dibutyltin dilaurate, tetrabutyl titanate or zinc acetate.
3. 3. The method for preparing a high-strength high-light-transmittance bio-based polyurethane film according to claim 1, wherein the catalyst is used in an amount of 0.25 to 0.5wt% of malic acid in the step (1).
4. 4. The method for preparing the high-strength high-light-transmittance bio-based polyurethane film according to claim 1, wherein isocyanate in the step (2) is any one of isophorone diisocyanate, 2, 4-toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate or hexamethylene diisocyanate, and the organotin catalyst is any one of dibutyltin dilaurate or stannous octoate.
5. 5. The method for preparing the high-strength high-light-transmittance bio-based polyurethane film according to claim 1, wherein in the step (2), the organic tin catalyst is used in an amount of 0.25-0.5wt% of malic acid polyol, and the small molecule chain extender is any one of ethylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol or 1, 4-cyclohexanediol.
6. 6. The method for preparing a high-strength high-light-transmittance bio-based polyurethane film according to claim 1, wherein the organic solvent is any one of N, N-dimethylformamide, acetone, ethyl acetate, butyl acetate or dichloromethane.
7. 7. A high strength, high light transmission bio-based polyurethane film prepared according to the method of any one of claims 1-6, wherein the structural formula is shown in formula I: , wherein the R 1 structure is from 、 、 Or (b) Any of the R 2 structures is from 、 、 、 Or (b) Any of the R 3 structures is from 、 、 、 、 Or (b) Any of the R 4 structures is from Or (b) Any one of them.

Description

High-strength high-light-transmittance bio-based polyurethane film and preparation method thereof Technical Field The invention belongs to the field of bio-based functional polymer materials, and particularly relates to a high-strength high-light-transmittance bio-based polyurethane film and a preparation method thereof. Background The mulching film covering technology is used as a low-cost and practical planting technology and is widely applied to the field of agricultural planting. The technology can reduce the striking of rainwater on crops, effectively reduce the evaporation of water in soil, keep the soil at proper temperature and humidity, promote the absorption and growth and development of the crops on the water, and remarkably improve the crop yield. The agricultural mulching film is a key material of the mulching film covering technology, and the agricultural mulching film can be corroded by wind sand and rainwater in actual use, so that the agricultural mulching film material is required to have higher mechanical strength and corrosion resistance, and the growth of crops needs sufficient illumination, so that the agricultural mulching film also needs to have excellent light transmittance. The traditional agricultural mulching film material is Polyethylene (PE), and the material has excellent light transmittance but relatively poor mechanical strength and corrosion resistance. Polyurethane materials have irreplaceable functions in the fields of foam, medical equipment, adhesive/sealant, paint, packaging materials and the like due to the designability of molecular structures, and are known as universal high polymer materials. In the field of agricultural mulching films, the polyurethane material has good application prospect due to excellent corrosion resistance and mechanical properties. However, the traditional polyurethane materials are the same as the polyethylene materials, are petroleum-based materials, are non-renewable in raw materials, have no degradability in natural environment, and are stressed in sustainable development of environment and resources. Disclosure of Invention In order to solve the problems, the invention provides a high-strength high-light-transmittance bio-based polyurethane film and a preparation method thereof. The technical scheme of the invention is as follows: the preparation method of the high-strength high-light-transmittance bio-based polyurethane film comprises the following steps: (1) Uniformly mixing malic acid and aromatic ring dihydric alcohol, adding a catalyst dissolved in an organic solvent, reacting under the protection of 130-140℃, N 2 until the acid value is reduced to 1mgKOH/g, stopping the reaction, and cooling to obtain the malic acid polyhydric alcohol. Preferably, the aromatic ring dihydric alcohol is any one of 1, 4-dihydroxybenzene, hydroquinone dihydroxyethyl ether, resorcinol dihydroxyethyl ether or bisphenol A, and the catalyst is any one of dibutyl tin dilaurate, tetrabutyl titanate or zinc acetate. The molar ratio of malic acid to aromatic ring dihydric alcohol is 1:2, and the catalyst dosage is 0.25-0.5wt% of malic acid. (2) The method comprises the steps of dehydrating malic acid polyol, mixing the malic acid polyol with isocyanate and an organotin catalyst, dissolving the mixture in an organic solvent, reacting for 2 hours at 75-85 ℃ to obtain an isocyanato-terminated bio-based polyurethane prepolymer, dissolving the bio-based polyurethane prepolymer and a small molecular chain extender in the organic solvent, and reacting for 1 hour at 35-45 ℃ to obtain the isocyanato-terminated bio-based polyurethane. Preferably, the isocyanate is any one of isophorone diisocyanate, 2, 4-toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate or hexamethylene diisocyanate, and the organotin catalyst is any one of dibutyltin dilaurate or stannous octoate. The molar ratio of the malic acid polyol to the isocyanate is 3:1, the using amount of the organotin catalyst is 0.25-0.5wt% of the malic acid polyol, and the small molecular chain extender is any one of ethylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol or 1, 4-cyclohexanediol, wherein the molar ratio of the small molecular chain extender to the malic acid polyol is 1.5:1. (3) Dissolving coumarin derivative monomer and the bio-based polyurethane prepared in the step (2) in an organic solvent, reacting for 1h at 35-45 ℃ to obtain the bio-based polyurethane capped by the coumarin derivative monomer, dissolving the bio-based polyurethane capped by the coumarin derivative monomer in the organic solvent, pouring the bio-based polyurethane into a polytetrafluoroethylene plate, placing the polytetrafluoroethylene plate into a baking oven, drying at 80 ℃ for 24-48h, and placing the polytetrafluoroethylene plate into an ice bath for cooling for 30min to obtain the high-strength high-light-transmittance bio-based polyurethane film. Preferably, the