A degradable resin and preparation method

Abstract

The present invention relates to the technical field of polyurethane resins and discloses a degradable resin and a preparation method. The degradable resin of the present invention comprises 100 parts by weight of polylactic acid diol, 24-35 parts by weight of diisocyanate monomer, 4-16 parts by weight of modified cellulose, etc. Cellulose itself has good biodegradability. At the same time, the modified cellulose contains a large number of biodegradable ester groups, which further improves the biodegradability of the polyurethane resin. The modified cellulose also contains a large number of hydrophilic sulfonic acid anions and quaternary ammonium salt cations, which endow the polyurethane resin with good hydrophilic water absorption, promote the hydrolysis of polylactic acid molecular chains and cellulose ester groups in the polyurethane resin, thereby improving the hydrolysis weight loss rate of the resin and showing excellent degradation performance.

Description

Technical Field

[0001] The present invention relates to the technical field of polyurethane resins, in particular to a degradable resin and a preparation method thereof. Background Art

[0002] Polyurethane is a high-performance polymer resin with high mechanical strength, high toughness, and excellent heat resistance. It is widely used in coatings, insulation materials, medical supplies, and disposable hygiene products. Polyurethane made from raw materials such as polylactic acid diol and polyester polyol is biodegradable, environmentally friendly, and has low pollution, conforming to the concept of green chemistry and possessing broad application prospects.

[0003] Adding biomass resources such as cellulose to polyurethane can improve its performance such as being degradable. Cellulose is cheap and easy to obtain, biodegradable, and contains a large amount of active hydroxyl groups. It can react with reagents such as 3-chloro-2-hydroxypropyltrimethylammonium chloride and chlorosulfonic acid to generate cationic cellulose, sulfonated cellulose, etc. Cellulose can also react with prepolymer monomers such as diisocyanates and acrylates to prepare composite materials such as polyurethane, acrylic resin, and polylactic acid. Announcement number is that the Chinese patent CN106947051B discloses a kind of polyurethane-grafted cellulose nanocrystal and preparation method thereof, polyurethane chains are grafted onto the cellulose nanocrystal surface, solves the problems such as the poor dispersibility of cellulose nanocrystal in organic solvents and polymer matrices, but this patent does not solve the problem that the biodegradability and hydrolyzability of cellulose polyurethane composite material are poor. Summary of the Invention

[0004] (1) Technical problems solved: In response to the shortcomings of the existing technology, the present invention provides a degradable resin and a preparation method, which solves the problem of poor biodegradation and hydrolysis performance of polyurethane resin.

[0005] (II) Technical Solution: A biodegradable resin and preparation method, the biodegradable resin comprising 100 parts by weight of polylactic acid diol, 24-35 parts by weight of diisocyanate monomer, 2.1-3.3 parts by weight of diol chain extender, 4-16 parts by weight of modified cellulose, and 0.1-0.16 parts by weight of an organotin catalyst. The preparation method of the biodegradable resin is as follows:

[0006] (1) Add cellulose, a modifier, and 4-dimethylaminopyridine to tetrahydrofuran, heat and stir, then cool in an ice-water bath, add dicyclohexylcarbodiimide, and after the reaction, concentrate the solution under reduced pressure, wash with ethanol, and dry to obtain modified cellulose. The reaction formula is:

[0007] .

[0008] (2) Dry polylactic acid diol, diisocyanate monomer, and organotin catalyst are mixed and reacted at 70-80°C in a nitrogen atmosphere for 2-3 hours. Then, diol chain extender, modified cellulose, and acetone solvent are added. The temperature is lowered to 40-50°C and the reaction is continued for 1-2 hours. The acetone solvent is removed and the mixture is dried to obtain a biodegradable resin.

[0009] Furthermore, the diisocyanate monomer includes isophorone diisocyanate, toluene diisocyanate, hexamethylene diisocyanate or diphenylmethane diisocyanate.

[0010] Furthermore, the diol chain extender includes ethylene glycol, 1,4-butanediol, 1,6-hexanediol or diethylene glycol.

[0011] Furthermore, the organotin catalyst is dibutyltin dilaurate.

[0012] Furthermore, in (1), the amount of cellulose is 100 parts by weight, the modifier is 40-120 parts by weight, 4-dimethylaminopyridine is 12-40 parts by weight, and dicyclohexylcarbodiimide is 28-86 parts by weight.

[0013] Furthermore, the reaction in (1) is stirred at 15-40°C for 18-36 hours.

[0014] Furthermore, the preparation method of the modifier is as follows: 54-80 parts by weight of succinic anhydride, 100 parts by weight of hydroxyethyl betaine, and 3-6 parts by weight of pyridine are added to toluene, heated to 70-90°C, stirred for reaction for 18-24 hours, concentrated under reduced pressure, washed with acetone, and then recrystallized and purified in water to obtain the modifier. The reaction formula is:

[0015] .

[0016] (III) Beneficial technical effects: The present invention utilizes the carboxyl group of the modifier to undergo an esterification reaction with the hydroxyl group of cellulose to obtain modified cellulose, thereby introducing multiple ester groups, as well as sulfonic acid anions and quaternary ammonium salt cations into the cellulose matrix.

[0017] The invention uses polylactic acid diol and diisocyanate monomer as polymerization monomers, and adds modified cellulose during the polyurethane chain extension reaction. The cellulose itself has good biodegradability, and the modified cellulose contains a large number of biodegradable ester groups, which further improves the biodegradability of the polyurethane resin. In addition, the modified cellulose contains a large number of hydrophilic sulfonic acid anions and quaternary ammonium salt cations, which endows the polyurethane resin with good hydrophilic water absorption, promotes the hydrolysis of polylactic acid molecular chains and cellulose ester groups in the polyurethane resin, thereby improving the hydrolysis weight loss rate of the resin and showing excellent degradation performance. DETAILED DESCRIPTION

[0018] In order to make the technical solution of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below. It should be noted that the following embodiments are only used to better understand the technical solution of the present invention and should not be understood as limiting the present invention.

[0019] Cellulose model TL-003 was purchased from Nanjing Tianlu Nano Technology Co., Ltd. Sulfonated modified cellulose model TL-005 was purchased from Nanjing Tianlu Nano Technology Co., Ltd. Cationic cellulose was purchased from Hubei Xinjiecheng Chemical Technology Co., Ltd.

[0020] Hydroxyethyl betaine was prepared according to the method of the journal J. Chem. Sci. Volume 128, pages 1277–1284, (2016) in the literature "Functionalized dicationic ionic liquids: Green and efficient alternatives for catalysts in phthalate plasticizers preparation": 100 mmol of N,N-dimethylethanolamine was added to 120 mL of toluene, and after stirring, 100 mmol of 1,4-butane sultone was added dropwise at 0°C, heated to 110°C, and refluxed under condensation for 12 hours. After filtering, the precipitate was washed with ether and dried to obtain hydroxyethyl betaine with the structural formula . Example 1

[0021] (1) Add 5.4 g of succinic anhydride, 10 g of hydroxyethyl betaine, and 0.6 g of pyridine to 150 mL of toluene, heat to 70 °C, stir and react for 24 h, concentrate under reduced pressure, wash the product with acetone, and then recrystallize and purify it in water to obtain a modifier.

[0022] (2) To 2 L of tetrahydrofuran, add 30 g of cellulose, 12 g of a modifier, and 3.6 g of 4-dimethylaminopyridine. Heat and stir, then cool in an ice-water bath. Add 8.4 g of dicyclohexylcarbodiimide and stir at 20 °C for 18 h. Concentrate the solution under reduced pressure, wash with ethanol, and dry to obtain modified cellulose.

[0023] (3) 500 g of dried polylactic acid diol 2000, 154 g of isophorone diisocyanate, and 0.6 g of dibutyltin dilaurate were mixed and reacted at 80 °C in a nitrogen atmosphere for 2 h. Then, 16.5 g of chain extender 1,4-butanediol, 20 g of modified cellulose, and 0.9 L of acetone solvent were added. The temperature was lowered to 45 °C and reacted for 1 h. The acetone solvent was removed and the mixture was dried to obtain a biodegradable resin. Example 2

[0024] (1) Add 8 g of succinic anhydride, 10 g of hydroxyethyl betaine, and 0.3 g of pyridine to 200 mL of toluene, heat to 90 °C, stir and react for 18 h, concentrate under reduced pressure, wash the product with acetone, and then recrystallize and purify it in water to obtain a modifier.

[0025] (2) Add 30 g of cellulose, 20 g of a modifier, and 6 g of 4-dimethylaminopyridine to 2 L of tetrahydrofuran, heat with stirring, and then cool in an ice-water bath. Add 14 g of dicyclohexylcarbodiimide and stir at 15 °C for 36 h. Concentrate the solution under reduced pressure, wash with ethanol, and dry to obtain modified cellulose.

[0026] (3) 500 g of dried polylactic acid diol 2000, 175 g of diphenylmethane diisocyanate, and 0.6 g of dibutyltin dilaurate were mixed and reacted at 70 °C in a nitrogen atmosphere for 3 h. Then, 14.6 g of chain extender 1,6-hexanediol, 40 g of modified cellulose, and 1 L of acetone solvent were added. The temperature was lowered to 40 °C and reacted for 2 h. The acetone solvent was removed and the mixture was dried to obtain a biodegradable resin. Example 3

[0027] (1) Prepare the modifier according to the method of Example 1.

[0028] (2) To 2.5 L of tetrahydrofuran, add 30 g of cellulose, 28 g of a modifier, and 9.3 g of 4-dimethylaminopyridine. Heat and stir, then cool in an ice-water bath. Add 19.5 g of dicyclohexylcarbodiimide and stir at 40 °C for 18 h. Concentrate the solution under reduced pressure, wash with ethanol, and dry to obtain modified cellulose.

[0029] (3) 500 g of dried polylactic acid diol 2000, 137 g of toluene diisocyanate, and 0.5 g of dibutyltin dilaurate were mixed and reacted at 80 °C in a nitrogen atmosphere for 2 h. Then, 12.8 g of chain extender diethylene glycol, 50 g of modified cellulose, and 1 L of acetone solvent were added. The temperature was lowered to 50 °C and the mixture was reacted for 1 h. The acetone solvent was removed and the mixture was dried to obtain a biodegradable resin. Example 4

[0030] (1) Prepare the modifier according to the method of Example 1.

[0031] (2) To 2.5 L of tetrahydrofuran, add 30 g of cellulose, 36 g of a modifier, and 12 g of 4-dimethylaminopyridine. Heat and stir, then cool in an ice-water bath. Add 25.8 g of dicyclohexylcarbodiimide, and stir at 30 °C for 36 h. Concentrate the solution under reduced pressure, wash with ethanol, and dry to obtain modified cellulose.

[0032] (3) 500 g of dried polylactic acid diol 2000, 120 g of hexamethylene diisocyanate, and 0.8 g of dibutyltin dilaurate were mixed and reacted at 75 °C in a nitrogen atmosphere for 3 h. Then, 10.5 g of chain extender ethylene glycol, 80 g of modified cellulose, and 1 L of acetone solvent were added. The temperature was lowered to 50 °C and reacted for 1 h. The acetone solvent was removed and the mixture was dried to obtain a biodegradable resin.

[0033] Comparative Example 1

[0034] (1) 500 g of dried polylactic acid diol 2000, 154 g of isophorone diisocyanate, and 0.6 g of dibutyltin dilaurate were mixed and reacted at 80 °C in a nitrogen atmosphere for 2 h. Then, 16.5 g of chain extender 1,4-butanediol, 20 g of cellulose, and 0.9 L of acetone solvent were added. The temperature was lowered to 45 °C and the mixture was reacted for 1 h. The acetone solvent was removed and the mixture was dried to obtain a biodegradable resin.

[0035] Comparative Example 2

[0036] (1) Add 30g of cellulose and 12g of monoethyl succinate (structural formula: ), 3.6 g of 4-dimethylaminopyridine, heated with stirring and then cooled in an ice-water bath, 8.4 g of dicyclohexylcarbodiimide was added, and the mixture was stirred at 20°C for 18 hours. The solution was concentrated under reduced pressure, washed with ethanol, and dried to obtain modified cellulose.

[0037] (2) 500 g of dried polylactic acid diol 2000, 154 g of isophorone diisocyanate, and 0.6 g of dibutyltin dilaurate were mixed and reacted at 80 °C in a nitrogen atmosphere for 2 h. Then, 16.5 g of chain extender 1,4-butanediol, 20 g of modified cellulose, and 0.9 L of acetone solvent were added. The temperature was lowered to 45 °C and reacted for 1 h. The acetone solvent was removed and the mixture was dried to obtain a biodegradable resin.

[0038] Comparative Example 3

[0039] (1) 500 g of dried polylactic acid diol 2000, 154 g of isophorone diisocyanate, and 0.6 g of dibutyltin dilaurate were mixed and reacted at 80 °C in a nitrogen atmosphere for 2 h. Then, 16.5 g of chain extender 1,4-butanediol, 20 g of sulfonated modified cellulose, and 0.9 L of acetone solvent were added. The temperature was lowered to 45 °C and reacted for 1 h. The acetone solvent was removed and the mixture was dried to obtain a biodegradable resin.

[0040] Comparative Example 4

[0041] (1) 500 g of dried polylactic acid diol 2000, 154 g of isophorone diisocyanate, and 0.6 g of dibutyltin dilaurate were mixed and reacted at 80 °C in a nitrogen atmosphere for 2 h. Then, 16.5 g of chain extender 1,4-butanediol, 20 g of cationic cellulose, and 0.9 L of acetone solvent were added. The temperature was lowered to 45 °C and the mixture was reacted for 1 h. The acetone solvent was removed and the mixture was dried to obtain a biodegradable resin.

[0042] The biodegradability and biodegradation rate of polyurethane resin were tested according to GB / T 19277.2-2013 standard, and the test time was 30 days.

[0043] Weigh the polyurethane resin, add it to deionized water, heat it to 80°C, and keep it warm for 7 days. Remove the polyurethane resin, wash it with water, dry it, and weigh it. Calculate the hydrolysis weight loss W: W = (m0 - m0) / m0 × 100%. m0 is the mass before hydrolysis, and m is the mass after hydrolysis.

[0044] The tensile strength of polyurethane resin is tested according to GB / T 1040.1-2018 standard.

[0045] Table 1 Degradation properties of polyurethane resin

[0046]

[0047] The polyurethane resins of Examples 1-4 have a 30-day biodegradation rate of 58.7-66.4%, and a hydrolysis weight loss rate of 24.7-43.8%, exhibiting excellent biodegradability and hydrolysis properties. This is primarily due to the addition of modified cellulose during the chain extension reaction. Cellulose itself has excellent biodegradability, and the modified cellulose contains a large number of biodegradable ester groups, which further improves the biodegradability of the polyurethane resin. Furthermore, the modified cellulose contains a large number of hydrophilic sulfonic acid anions and quaternary ammonium salt cations, which impart excellent hydrophilic water absorption to the polyurethane resin, promote the hydrolysis of the polylactic acid molecular chains and cellulose ester groups in the polyurethane resin, and thus improve the hydrolysis weight loss rate.

[0048] Compared with Example 1, the cellulose in Comparative Example 1 does not contain a biodegradable ester group, nor does it contain a hydrophilic sulfonic acid anion and a quaternary ammonium salt cation, resulting in a lower biodegradation rate and hydrolysis weight loss rate of the polyurethane resin; the modified cellulose obtained by the esterification reaction of monoethyl succinate and cellulose in Comparative Example 2 also does not contain a hydrophilic sulfonic acid anion and a quaternary ammonium salt cation, resulting in a lower hydrolysis weight loss rate of the polyurethane resin; the sulfonated modified cellulose in Comparative Example 3 does not contain a biodegradable ester group and a hydrophilic quaternary ammonium salt cation, and the cationic cellulose in Comparative Example 4 does not contain a biodegradable ester group and a hydrophilic sulfonate anion, resulting in a lower biodegradation rate and hydrolysis weight loss rate of both.

[0049] The above is only a specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed in this application should be covered by the scope of protection of the present application.

Claims

1. A degradable resin, characterized in that: The degradable resin comprises 100 parts by weight of polylactic acid diol, 24-35 parts by weight of diisocyanate monomer, 2.1-3.3 parts by weight of diol chain extender, 4-16 parts by weight of modified cellulose, and 0.1-0.16 parts by weight of organotin catalyst; The modified cellulose preparation method comprises: adding cellulose, a modifier, and 4-dimethylaminopyridine to tetrahydrofuran, heating and stirring, cooling in an ice-water bath, adding dicyclohexylcarbodiimide, and after reaction, concentrating the solution under reduced pressure, washing with ethanol, and drying to obtain the modified cellulose; The structural formula of the modifier is: .

2. A degradable resin according to claim 1, characterized in that: The diisocyanate monomer includes isophorone diisocyanate, toluene diisocyanate, hexamethylene diisocyanate or diphenylmethane diisocyanate.

3. A degradable resin according to claim 1, characterized in that: The diol chain extender includes ethylene glycol, 1,4-butanediol, 1,6-hexanediol or diethylene glycol.

4. A degradable resin according to claim 1, characterized in that: The organic tin catalyst is dibutyltin dilaurate.

5. The degradable resin according to claim 1, characterized in that: The amount of the cellulose used is 100 parts by weight, the modifier is 40-120 parts by weight, 4-dimethylaminopyridine is 12-40 parts by weight, and dicyclohexylcarbodiimide is 28-86 parts by weight.

6. The degradable resin according to claim 1, characterized in that: The reaction was stirred at 15-40 °C for 18-36 h.

7. The degradable resin according to claim 1, characterized in that: The preparation method of the modifier comprises: adding 54-80 parts by weight of succinic anhydride, 100 parts by weight of quaternary ammonium betaine hydroxyethyl sulfonate, and 3-6 parts by weight of pyridine to toluene, heating to 70-90° C., stirring for reaction for 18-24 hours, concentrating under reduced pressure, washing the product with acetone, and then recrystallizing and purifying it in water to obtain the modifier; The structural formula of the quaternary ammonium salt betaine of isethionate is .

8. A method for preparing a degradable resin according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: mixing dry polylactic acid diol, diisocyanate monomer, and organic tin catalyst, reacting them at 70-80° C. in a nitrogen atmosphere for 2-3 hours, then adding a diol chain extender, modified cellulose, and acetone solvent, lowering the temperature to 40-50° C., reacting them for 1-2 hours, removing the acetone solvent, and drying to obtain a degradable resin.

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