Degradable high-bio-content polyurethane foam and production method thereof

Abstract

The invention relates to the technical field of polyurethane foam, and particularly discloses degradable polyurethane foam with high bio-based content and a production method thereof.The production method comprises the steps that bio-based raw materials castor oil triglycidyl ether and isosorbide diglycidyl ether are adopted for synthesizing castor oil-isosorbide polycyclic carbonate; a vanillin-decamethylene diamine prepolymer is synthesized from vanillin and decamethylene diamine, diamine and cyclic carbonate are gradually polymerized through a generated carbamate bond to form a polyurethane elastomer, foaming is performed, and the degradable polyurethane foam with the high bio-based content is obtained.

Description

Technical Field

[0001] This invention relates to the field of polyurethane foam technology, specifically to a biodegradable polyurethane foam with high bio-based content and its production method. Background Technology

[0002] Polyurethane is a polymer material with excellent mechanical strength, processability, and durability. It is widely used in various industries. Common polyurethane products include polyurethane foam, polyurethane elastomers, polyurethane coatings, and polyurethane fibers. Its main synthesis method is the polymerization reaction between polyether or polyester polyol and isocyanate.

[0003] Traditionally, the polyols used in the synthesis of polyurethane are primarily derived from non-renewable petroleum resources, while isocyanates are typically obtained through the reaction of amines and highly toxic phosgene, posing adverse effects on the environment and human health. Furthermore, the inherent chemical stability of polyurethane makes it difficult to degrade in the natural environment. With the continuous growth in the consumption of polyurethane materials and the increasingly widespread application of short-life polyurethane products such as disposable packaging and cushioning materials, a large amount of waste polyurethane products are difficult to decompose naturally, placing enormous pressure on the environment. Therefore, promoting the transformation of polyurethane towards a green and sustainable direction is imperative. Using environmentally friendly bio-based polyols and isocyanates as synthetic raw materials reduces dependence on petroleum resources and toxic substances, and endows polyurethane materials with the ability to be decomposed by microorganisms or chemical processes in environments such as composting and soil, returning them to nature. This is crucial for fundamentally solving plastic pollution and achieving the sustainable development of polymer materials. Summary of the Invention

[0004] The purpose of this invention is to provide a biodegradable polyurethane foam with high bio-based content and its production method, thereby solving the problem of polyurethane foam materials being difficult to degrade naturally and causing environmental pollution.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A method for producing biodegradable polyurethane foam with high bio-based content, specifically comprising: Step 1: Using isosorbide diglycidyl ether and castor oil triglycidyl ether as raw materials, castor oil-isosorbide polycyclic carbonate was synthesized. Step 2: Using vanillin, glycerol triglycidyl ether and decanediamine as raw materials, a vanillin-decanediamine prepolymer was synthesized; Step 3: Using castor oil-isosorbitol polycyclic carbonate, vanillin-decanediamine prepolymer and decanediamine as raw materials, silanized cellulose nanofibers are added to synthesize non-isocyanate polyurethane elastomer. Then, the non-isocyanate polyurethane elastomer is foamed using supercritical CO2 technology to obtain degradable polyurethane foam with high bio-based content.

[0006] As a limitation of the present invention, the preparation method of the castor oil-isosorbitol polycyclic carbonate is as follows: Isosorbide diglycidyl ether was added to castor oil triglycidyl ether and stirred at 50-60℃ and 200-300 rpm for 20-30 min. Tetrabutylammonium bromide catalyst was added, the atmosphere was replaced with carbon dioxide and the pressure was increased to 2.5-3.0 MPa, and the reaction was carried out at 110-120℃ and 400-500 rpm for 10-12 h. After the reaction was completed, the mixture was cooled to room temperature and the pressure was released to obtain castor oil-isosorbide polycyclic carbonate.

[0007] As a limitation of the present invention, the mass ratio of isosorbide diglycidyl ether, castor oil triglycidyl ether and the catalyst tetrabutylammonium bromide is (20-30):(40-50):(1.4-1.6).

[0008] Under the catalysis of tetrabutylammonium bromide, the epoxy groups on castor oil triglycidyl ether and isosorbide diglycidyl ether molecules undergo ring-opening to form an intermediate structure. CO2 molecules then insert into this intermediate structure under high temperature and pressure, leading to cyclization and ring closure to form a stable five-membered cyclic carbonate structure. Castor oil triglycidyl ether contains long aliphatic chains, which act as "flexible segments" in the polyurethane structure, enhancing the flexibility and mobility of the polyurethane segments and improving the elasticity, toughness, and impact resistance of the polyurethane foam. Isosorbide contains rigid furan ring structures, which act as "rigid segments" in the polyurethane structure, enhancing the rigidity of the polyurethane segments and intermolecular forces, thereby improving the strength and thermal stability of the polyurethane foam.

[0009] As a limitation of this invention, the method for preparing the vanillin-decanediamine prepolymer is as follows: Vanillin was added to glycerol triglycidyl ether and stirred at 50-60℃ and 200-300 rpm for 20-30 min. Catalyst DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) was added, and the reaction was carried out under nitrogen protection at 110-120℃ and 400-500 rpm for 12-16 h. After the reaction was completed, the mixture was cooled and added to ethyl acetate. The mixture was washed successively with saturated sodium carbonate solution and deionized water. The liquid was separated, and the organic phase was dried with anhydrous magnesium sulfate. After removing ethyl acetate by vacuum distillation at 50-60℃, the mixture was added to decanediamine and reacted under nitrogen protection at 100-110℃ and 400-500 rpm for 2-4 h. After the reaction was completed, the mixture was cooled to obtain vanillin-decediamine prepolymer.

[0010] As a limitation of the present invention, the mass ratio of vanillin, glycerol triglycidyl ether, catalyst DBU and decanediamine is (37-41):(20-22):(0.6-0.7):(20-24).

[0011] Under the action of catalyst DBU, vanillin loses the proton on its phenolic hydroxyl group to generate an active phenoxy anion. The phenoxy anion undergoes a ring-opening reaction with the epoxy ring in the glycerol triglycidyl ether molecule. The vanillin structure is linked to the glycerol structure of the glycerol triglycidyl ether via an ether bond to form an intermediate. The aldehyde group retained at the end of the intermediate further undergoes a condensation reaction with the primary amino group of decanediamine to generate a Schiff base structure. The Schiff base structure is reduced in situ with the amine (decanediamine) in the system to generate a stable secondary amine bond, forming a vanillin-decanediamine prepolymer. The vanillin-decanediamine prepolymer structure contains a rigid trivanillin structure, which acts as a rigid crosslinking point in the polymer network, restricting chain segment movement and improving the strength and rigidity of the polymer foam. The structure also contains flexible long aliphatic chains (derived from decanediamine) connecting the rigid nodes, improving the toughness and impact resistance of the polymer foam.

[0012] As a limitation of this invention, the preparation method of the non-isocyanate type polyurethane elastomer is as follows: Silane-modified cellulose nanofibers were added to N,N-dimethylformamide and stirred at 200-300 rpm for 20-30 min, followed by ultrasonic dispersion for 20-30 min to obtain a cellulose nanofiber dispersion. Decanediamine and vanillin-decanediamine prepolymer were added to N,N-dimethylformamide and stirred at 200-300 rpm for 20-30 min. Catalyst DABCO (1,4-diazabicyclo[2.2.2]octane) was added, and stirring continued for 20-30 min to obtain a mixed diamine solution. Castor oil-isosorbitol polyol... A ring-shaped carbonate was added to N,N-dimethylformamide and stirred at 90-100℃ and 200-300rpm for 20-30min under nitrogen protection. A cellulose nanofiber dispersion was then added, and stirring continued for another 20-30min. A mixed diamine solution was then added dropwise at 90-100℃ and 200-300rpm, and the reaction was stirred for 10-14h. After the reaction was completed, the mixture was cooled to room temperature, added to deionized water to precipitate, filtered, washed with methanol, and vacuum dried at 60-70℃ for 16-20h to obtain a non-isocyanate type polyurethane elastomer.

[0013] As a limitation of the present invention, the mass ratio of the silane-modified cellulose nanofibers, decanediamine, vanillin-decanediamine prepolymer, castor oil-isosorbitol polycyclic carbonate and catalyst DABCO is (20-40):(130-150):(40-60):(500-520):(5-7).

[0014] In diamine (decanediamine, vanillin-decanediamine prepolymer) molecules, the primary amino group acts as a nucleophile to attack the sterically less hindered carbon atom in the five-membered ring of cyclic carbonate. The cyclic carbonate ring opens, and the nitrogen atom of the primary amino group forms a stable CN bond with the carbonyl carbon after ring opening, while generating a side chain hydroxyl group. During the reaction, the diamine and cyclic carbonate gradually polymerize through the generated urethane bonds to form a polyurethane network.

[0015] As a limitation of this invention, the preparation method of the silane-modified nanocellulose fibers is as follows: Cellulose nanofibers were added to deionized water and stirred at 30-40℃ and 200-300 rpm for 20-30 min. The mixture was then ultrasonically dispersed for 20-30 min, and the pH was adjusted to 4-5. Silane coupling agent KH-550 was added, and the mixture was reacted at 60-70℃ and 400-500 rpm for 6-8 h. After the reaction was completed, the mixture was cooled, washed with ethanol and deionized water, and vacuum dried at 70-80℃ for 4-6 h to obtain silane-modified cellulose nanofibers. The mass ratio of cellulose nanofibers to silane coupling agent KH-550 is (30-50):(3-4).

[0016] The silanol groups generated by the hydrolysis of the silane coupling agent KH-550 undergo a condensation reaction with the hydroxyl groups on the surface of cellulose nanofibers, forming stable covalent bonds. The cellulose nanofibers are then grafted with long organic chains bearing primary amino groups at their ends. These grafted organic chains lower the surface energy of the cellulose nanofibers, allowing for uniform dispersion of the fibers within the polyurethane foam and improving their compatibility with the foam. The terminal primary amino groups participate in the polyurethane synthesis process, chemically bonding with cyclic carbonate groups in the system. The fibers then become chemical crosslinking points in the polyurethane foam, enhancing its strength, toughness, modulus, and thermal stability.

[0017] As a limitation of the present invention, the method for preparing the biodegradable polyurethane foam with high bio-based content is as follows: Non-isocyanate polyurethane elastomer is placed in the foaming chamber of an autoclave, and carbon dioxide is used to replace the gas in the autoclave. Then, the temperature is raised to 140-150℃, and carbon dioxide is introduced to raise the pressure in the autoclave to 8-12MPa. After holding the temperature and pressure for 0.5-1.5h, the pressure is quickly released to atmospheric pressure for foaming. After cooling and shaping, biodegradable polyurethane foam with high bio-based content is obtained.

[0018] Under high temperature and high pressure conditions, supercritical carbon dioxide dissolves and permeates into the polyurethane elastomer and disperses uniformly. When the system pressure is rapidly released to atmospheric pressure, the supercritical carbon dioxide dispersed in the polyurethane elastomer is converted into a highly supersaturated gaseous state, forming a large number of uniformly distributed bubble nuclei in the polyurethane elastomer and expanding and growing. The polyurethane elastomer foams and expands rapidly. Then, as the temperature is lowered, the viscosity of the polymer increases sharply, the chain segment movement is hindered, and the expanded cell structure is fixed, forming a polyurethane foam material with uniform cell size and intact cell walls.

[0019] A biodegradable polyurethane foam with high bio-based content, produced according to the production method described in any one of the preceding claims.

[0020] Compared with the prior art, the beneficial effects of the present invention are: This invention synthesizes a castor oil-isosorbate polycyclic carbonate using bio-based raw materials castor oil triglycidyl ether and isosorbide diglycidyl ether. Castor oil triglycidyl ether contains long fatty chains, which act as "flexible segments" in the polyurethane structure, enhancing the flexibility and mobility of the polyurethane segments and improving the elasticity, toughness, and impact resistance of the polyurethane foam. Isosorbide contains rigid furan ring structures, which act as "rigid segments" in the polyurethane structure, enhancing the rigidity of the polyurethane segments and intermolecular forces, thus improving the strength and thermal stability of the polyurethane foam. A vanillin-decanediamine prepolymer is synthesized using vanillin and decanediamine. The diamine and the cyclic carbonate gradually polymerize through the generated urethane bonds to form a polyurethane elastomer, which is then foamed to obtain a biodegradable polyurethane foam with a high bio-based content. Detailed Implementation

[0021] 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, not all embodiments. The terminology used in the embodiments is for describing specific implementation schemes, not for limiting the scope of protection of the present invention. The dosages in the embodiments are laboratory-scale tests and can be scaled up proportionally. 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.

[0022] Cellulose nanofibers (diameter: 30nm, length: 500nm).

[0023] Example 1: A method for producing biodegradable polyurethane foam with high bio-based content, specifically as follows: Step 1: Add 20g of isosorbide diglycidyl ether to 50g of castor oil triglycidyl ether, stir at 60℃ and 200rpm for 20min, add 1.4g of tetrabutylammonium bromide catalyst, replace the atmosphere with carbon dioxide and pressurize to 3.0MPa, stir at 120℃ and 400rpm for 10h, after the reaction is completed, cool to room temperature, depressurize, and obtain castor oil-isosorbide polycyclic carbonate; Step 2: Add 37g vanillin to 20g glycerol triglycidyl ether and stir at 60℃ and 200rpm for 20min. Add 0.6g catalyst DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) and react at 110℃ and 400rpm for 12h under nitrogen protection. After the reaction is complete, cool and add to ethyl acetate. Wash with saturated sodium carbonate solution and deionized water in sequence. Separate the liquid and dry the organic phase with anhydrous magnesium sulfate. Remove ethyl acetate by vacuum distillation at 50℃ and add to 20g decanediamine. React at 100℃ and 400rpm for 2h under nitrogen protection. After the reaction is complete, cool to obtain vanillin-decediamine prepolymer. Step 3: Add 30g of cellulose nanofibers to 200mL of deionized water, stir at 40℃ and 200rpm for 20min, sonicate for 20min, adjust the pH to 4, add 3g of silane coupling agent KH-550, react at 60℃ and 400rpm for 6h, cool after the reaction is complete, wash with ethanol and deionized water, and vacuum dry at 70℃ for 4h to obtain silane-modified cellulose nanofibers; Step 4: Add 20g of silane-modified cellulose nanofibers to 1L of N,N-dimethylformamide, stir at 200rpm for 20min, and ultrasonically disperse for 20min to obtain a cellulose nanofiber dispersion. Add 150g of decanediamine and 40g of vanillin-decanediamine prepolymer to 1L of N,N-dimethylformamide. In N,N-dimethylformamide, the mixture was stirred at 200 rpm for 20 min, and 5 g of catalyst DABCO (1,4-diazabicyclo[2.2.2]octane) was added. The mixture was stirred for another 20 min to obtain a mixed diamine solution. 500 g of castor oil-isosorbitol polycyclic carbonate was added to 1 L of N,N-dimethylformamide. Under nitrogen protection, the mixture was stirred at 90 °C and 200 rpm for 30 min. Cellulose nanofiber dispersion was added, and the mixture was stirred for another 30 min. The mixed diamine solution was added dropwise at 90 °C and 200 rpm, and the mixture was stirred for 10 h. After the reaction was completed, the mixture was cooled to room temperature, added to deionized water to precipitate, filtered, washed with methanol, and dried under vacuum at 70 °C for 20 h to obtain a non-isocyanate type polyurethane elastomer. Step 5: Place the non-isocyanate polyurethane elastomer into the foaming chamber of the autoclave, replace the gas in the autoclave with carbon dioxide, then raise the temperature to 140°C, introduce carbon dioxide to raise the pressure in the autoclave to 10MPa, keep the temperature and pressure for 1 hour, then quickly depressurize to atmospheric pressure for foaming, cool and set to obtain biodegradable polyurethane foam with high bio-based content.

[0024] Example 2: A method for producing biodegradable polyurethane foam with high bio-based content, specifically as follows: Step 1: Add 25g of isosorbide diglycidyl ether to 45g of castor oil triglycidyl ether, stir at 60℃ and 200rpm for 20min, add 1.5g of tetrabutylammonium bromide catalyst, replace the atmosphere with carbon dioxide and pressurize to 3.0MPa, stir at 120℃ and 400rpm for 10h, after the reaction is completed, cool to room temperature, depressurize, and obtain castor oil-isosorbide polycyclic carbonate; Step 2: Add 39g vanillin to 21g glycerol triglycidyl ether and stir at 60℃ and 200rpm for 20min. Add 0.6g catalyst DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) and react at 110℃ and 400rpm for 12h under nitrogen protection. After the reaction is complete, cool and add to ethyl acetate. Wash with saturated sodium carbonate solution and deionized water in sequence. Separate the liquid and dry the organic phase with anhydrous magnesium sulfate. Remove ethyl acetate by vacuum distillation at 50℃ and add to 22g decanediamine. React at 100℃ and 400rpm for 2h under nitrogen protection. After the reaction is complete, cool to obtain vanillin-decediamine prepolymer. Step 3: Add 30g of cellulose nanofibers to 200mL of deionized water, stir at 40℃ and 200rpm for 20min, sonicate for 20min, adjust the pH to 4, add 3g of silane coupling agent KH-550, react at 60℃ and 400rpm for 6h, cool after the reaction is complete, wash with ethanol and deionized water, and vacuum dry at 70℃ for 4h to obtain silane-modified cellulose nanofibers; Step 4: Add 30g of silane-modified cellulose nanofibers to 1L of N,N-dimethylformamide, stir at 200rpm for 20min, and ultrasonically disperse for 20min to obtain a cellulose nanofiber dispersion. Add 140g of decanediamine and 50g of vanillin-decanediamine prepolymer to 1L of N,N-dimethylformamide. In N,N-dimethylformamide, the mixture was stirred at 200 rpm for 20 min, and 5 g of catalyst DABCO (1,4-diazabicyclo[2.2.2]octane) was added. The mixture was stirred for another 20 min to obtain a mixed diamine solution. 510 g of castor oil-isosorbitol polycyclic carbonate was added to 1 L of N,N-dimethylformamide. Under nitrogen protection, the mixture was stirred at 90 °C and 200 rpm for 30 min. Cellulose nanofiber dispersion was added, and the mixture was stirred for another 30 min. The mixed diamine solution was added dropwise at 90 °C and 200 rpm, and the mixture was stirred for 10 h. After the reaction was completed, the mixture was cooled to room temperature, added to deionized water to precipitate, filtered, washed with methanol, and dried under vacuum at 70 °C for 20 h to obtain a non-isocyanate type polyurethane elastomer. Step 5: Place the non-isocyanate polyurethane elastomer into the foaming chamber of the autoclave, replace the gas in the autoclave with carbon dioxide, then raise the temperature to 140°C, introduce carbon dioxide to raise the pressure in the autoclave to 10MPa, keep the temperature and pressure for 1 hour, then quickly depressurize to atmospheric pressure for foaming, cool and set to obtain biodegradable polyurethane foam with high bio-based content.

[0025] Example 3: A method for producing biodegradable polyurethane foam with high bio-based content, specifically as follows: Step 1: Add 30g of isosorbide diglycidyl ether to 40g of castor oil triglycidyl ether, stir at 60℃ and 200rpm for 20min, add 1.6g of tetrabutylammonium bromide catalyst, replace the atmosphere with carbon dioxide and pressurize to 3.0MPa, stir at 120℃ and 400rpm for 10h, after the reaction is completed, cool to room temperature, depressurize, and obtain castor oil-isosorbide polycyclic carbonate; Step 2: Add 41g vanillin to 22g glycerol triglycidyl ether and stir at 60℃ and 200rpm for 20min. Add 0.6g catalyst DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) and react at 110℃ and 400rpm for 12h under nitrogen protection. After the reaction is complete, cool and add to ethyl acetate. Wash with saturated sodium carbonate solution and deionized water in sequence. Separate the liquid and dry the organic phase with anhydrous magnesium sulfate. Remove ethyl acetate by vacuum distillation at 50℃ and add to 24g decanediamine. React at 100℃ and 400rpm for 2h under nitrogen protection. After the reaction is complete, cool to obtain vanillin-decediamine prepolymer. Step 3: Add 30g of cellulose nanofibers to 200mL of deionized water, stir at 40℃ and 200rpm for 20min, sonicate for 20min, adjust the pH to 4, add 3g of silane coupling agent KH-550, react at 60℃ and 400rpm for 6h, cool after the reaction is complete, wash with ethanol and deionized water, and vacuum dry at 70℃ for 4h to obtain silane-modified cellulose nanofibers; Step 4: Add 40g of silane-modified cellulose nanofibers to 1L of N,N-dimethylformamide, stir at 200rpm for 20min, and ultrasonically disperse for 20min to obtain a cellulose nanofiber dispersion. Add 130g of decanediamine and 60g of vanillin-decanediamine prepolymer to 1L of N,N-dimethylformamide. In N,N-dimethylformamide, the mixture was stirred at 200 rpm for 20 min, and 5 g of catalyst DABCO (1,4-diazabicyclo[2.2.2]octane) was added. The mixture was stirred for another 20 min to obtain a mixed diamine solution. 520 g of castor oil-isosorbitol polycyclic carbonate was added to 1 L of N,N-dimethylformamide. Under nitrogen protection, the mixture was stirred at 90 °C and 200 rpm for 30 min. Cellulose nanofiber dispersion was added, and the mixture was stirred for another 30 min. The mixed diamine solution was added dropwise at 90 °C and 200 rpm, and the mixture was stirred for 10 h. After the reaction was completed, the mixture was cooled to room temperature, added to deionized water to precipitate, filtered, washed with methanol, and dried under vacuum at 70 °C for 20 h to obtain a non-isocyanate type polyurethane elastomer. Step 5: Place the non-isocyanate polyurethane elastomer into the foaming chamber of the autoclave, replace the gas in the autoclave with carbon dioxide, then raise the temperature to 140°C, introduce carbon dioxide to raise the pressure in the autoclave to 10MPa, keep the temperature and pressure for 1 hour, then quickly depressurize to atmospheric pressure for foaming, cool and set to obtain biodegradable polyurethane foam with high bio-based content.

[0026] Based on Example 1, the following comparative experiments were conducted, specifically Comparative Example 1, Comparative Example 2, and Comparative Example 3, as described below: Comparative Example 1: This comparative example relates to a method for producing biodegradable polyurethane foam with high bio-based content. The difference from Example 1 is that vanillin-decanediamine prepolymer was not added. Specifically: Step 1: Add 20g of isosorbide diglycidyl ether to 50g of castor oil triglycidyl ether, stir at 60℃ and 200rpm for 20min, add 1.4g of tetrabutylammonium bromide catalyst, replace the atmosphere with carbon dioxide and pressurize to 3.0MPa, stir at 120℃ and 400rpm for 10h, after the reaction is completed, cool to room temperature, depressurize, and obtain castor oil-isosorbide polycyclic carbonate; Step 2: Add 30g of cellulose nanofibers to 200mL of deionized water, stir at 40℃ and 200rpm for 20min, sonicate for 20min, adjust the pH to 4, add 3g of silane coupling agent KH-550, react at 60℃ and 400rpm for 6h, cool after the reaction is complete, wash with ethanol and deionized water, and vacuum dry at 70℃ for 4h to obtain silane-modified cellulose nanofibers; Step 3: Add 20g of silane-modified cellulose nanofibers to 1L of N,N-dimethylformamide, stir at 200rpm for 20min, and ultrasonically disperse for 20min to obtain a cellulose nanofiber dispersion. Add 190g of decanediamine to 1L of N,N-dimethylformamide, stir at 200rpm for 20min, add 5g of catalyst DABCO (1,4-diazabicyclo[2.2.2]octane), and continue stirring for 20min to obtain a mixed diamine solution. Add 500g of castor oil-isosorbitol polycyclic carbonate to 1L of N,N-dimethylformamide, and stir at 90℃ and 200rpm for 30min under nitrogen protection. Add the cellulose nanofiber dispersion and continue stirring for 30min. At 90℃ and 200rpm, add the mixed diamine solution dropwise and stir for 10h. After the reaction is complete, cool to room temperature, add to deionized water to precipitate, filter, wash with methanol, and vacuum dry at 70℃ for 20h to obtain a non-isocyanate type polyurethane elastomer. Step 5: Place the non-isocyanate polyurethane elastomer into the foaming chamber of the autoclave, replace the gas in the autoclave with carbon dioxide, then raise the temperature to 140°C, introduce carbon dioxide to raise the pressure in the autoclave to 10MPa, keep the temperature and pressure for 1 hour, then quickly depressurize to atmospheric pressure for foaming, cool and set to obtain biodegradable polyurethane foam with high bio-based content.

[0027] Comparative Example 2: This comparative example relates to a method for producing biodegradable polyurethane foam with high bio-based content. The difference from Example 1 is that bisphenol A diglycidyl ether is used instead of isosorbide diglycidyl ether. Specifically: Step 1: Add 20g of bisphenol A diglycidyl ether to 50g of castor oil triglycidyl ether, stir at 60℃ and 200rpm for 20min, add 1.4g of tetrabutylammonium bromide catalyst, replace the atmosphere with carbon dioxide and pressurize to 3.0MPa, stir at 120℃ and 400rpm for 10h, after the reaction is completed, cool to room temperature, depressurize, and obtain castor oil-bisphenol A polycyclic carbonate; Step 2: Add 37g vanillin to 20g glycerol triglycidyl ether and stir at 60℃ and 200rpm for 20min. Add 0.6g catalyst DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) and react at 110℃ and 400rpm for 12h under nitrogen protection. After the reaction is complete, cool and add to ethyl acetate. Wash with saturated sodium carbonate solution and deionized water in sequence. Separate the liquid and dry the organic phase with anhydrous magnesium sulfate. Remove ethyl acetate by vacuum distillation at 50℃ and add to 20g decanediamine. React at 100℃ and 400rpm for 2h under nitrogen protection. After the reaction is complete, cool to obtain vanillin-decediamine prepolymer. 30g of cellulose nanofibers were added to 200mL of deionized water, stirred at 40℃ and 200rpm for 20min, ultrasonically dispersed for 20min, the pH was adjusted to 4, 3g of silane coupling agent KH-550 was added, and the reaction was carried out at 60℃ and 400rpm for 6h. After the reaction was completed, the mixture was cooled, washed with ethanol and deionized water, and vacuum dried at 70℃ for 4h to obtain silane-modified cellulose nanofibers. Step 4: Add 20g of silane-modified cellulose nanofibers to 1L of N,N-dimethylformamide, stir at 200rpm for 20min, and ultrasonically disperse for 20min to obtain a cellulose nanofiber dispersion. Add 150g of decanediamine and 40g of vanillin-decanediamine prepolymer to 1L of N,N-dimethylformamide. In N,N-dimethylformamide, the mixture was stirred at 200 rpm for 20 min, and 5 g of catalyst DABCO (1,4-diazabicyclo[2.2.2]octane) was added. The mixture was stirred for another 20 min to obtain a mixed diamine solution. 500 g of castor oil-bisphenol A polycyclic carbonate was added to 1 L of N,N-dimethylformamide. Under nitrogen protection, the mixture was stirred at 90 °C and 200 rpm for 30 min. Cellulose nanofiber dispersion was added, and the mixture was stirred for another 30 min. The mixed diamine solution was added dropwise at 90 °C and 200 rpm, and the mixture was stirred for 10 h. After the reaction was completed, the mixture was cooled to room temperature, added to deionized water to precipitate, filtered, washed with methanol, and dried under vacuum at 70 °C for 20 h to obtain a non-isocyanate type polyurethane elastomer. Step 5: Place the non-isocyanate polyurethane elastomer into the foaming chamber of the autoclave, replace the gas in the autoclave with carbon dioxide, then raise the temperature to 140°C, introduce carbon dioxide to raise the pressure in the autoclave to 10MPa, keep the temperature and pressure for 1 hour, then quickly depressurize to atmospheric pressure for foaming, cool and set to obtain biodegradable polyurethane foam with high bio-based content.

[0028] Comparative Example 3: This comparative example relates to a method for producing biodegradable polyurethane foam with high bio-based content. The difference from Example 1 is that isophorone diamine is used instead of decanediamine. Specifically: Step 1: Add 20g of isosorbide diglycidyl ether to 50g of castor oil triglycidyl ether, stir at 60℃ and 200rpm for 20min, add 1.4g of tetrabutylammonium bromide catalyst, replace the atmosphere with carbon dioxide and pressurize to 3.0MPa, stir at 120℃ and 400rpm for 10h, after the reaction is completed, cool to room temperature, depressurize, and obtain castor oil-isosorbide polycyclic carbonate; Step 2: Add 37g vanillin to 20g glycerol triglycidyl ether and stir at 60℃ and 200rpm for 20min. Add 0.6g catalyst DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) and react at 110℃ and 400rpm for 12h under nitrogen protection. After the reaction is complete, cool and add to ethyl acetate. Wash with saturated sodium carbonate solution and deionized water in sequence. Separate the liquid and dry the organic phase with anhydrous magnesium sulfate. Remove ethyl acetate by vacuum distillation at 50℃ and add to 20g decanediamine. React at 100℃ and 400rpm for 2h under nitrogen protection. After the reaction is complete, cool to obtain vanillin-decediamine prepolymer. Step 3: Add 30g of cellulose nanofibers to 200mL of deionized water, stir at 40℃ and 200rpm for 20min, sonicate for 20min, adjust the pH to 4, add 3g of silane coupling agent KH-550, react at 60℃ and 400rpm for 6h, cool after the reaction is complete, wash with ethanol and deionized water, and vacuum dry at 70℃ for 4h to obtain silane-modified cellulose nanofibers; Step 4: Add 20g of silane-modified cellulose nanofibers to 1L of N,N-dimethylformamide, stir at 200rpm for 20min, and ultrasonically disperse for 20min to obtain a cellulose nanofiber dispersion. Add 150g of isophorone diamine and 40g of vanillin-decanediamine prepolymer to 1L of N,N-dimethylformamide. In N,N-dimethylformamide, the mixture was stirred at 200 rpm for 20 min, and 5 g of catalyst DABCO (1,4-diazabicyclo[2.2.2]octane) was added. The mixture was stirred for another 20 min to obtain a mixed diamine solution. 500 g of castor oil-isosorbitol polycyclic carbonate was added to 1 L of N,N-dimethylformamide. Under nitrogen protection, the mixture was stirred at 90 °C and 200 rpm for 30 min. Cellulose nanofiber dispersion was added, and the mixture was stirred for another 30 min. The mixed diamine solution was added dropwise at 90 °C and 200 rpm, and the mixture was stirred for 10 h. After the reaction was completed, the mixture was cooled to room temperature, added to deionized water to precipitate, filtered, washed with methanol, and dried under vacuum at 70 °C for 20 h to obtain a non-isocyanate type polyurethane elastomer. Step 5: Place the non-isocyanate polyurethane elastomer into the foaming chamber of the autoclave, replace the gas in the autoclave with carbon dioxide, then raise the temperature to 140°C, introduce carbon dioxide to raise the pressure in the autoclave to 10MPa, keep the temperature and pressure for 1 hour, then quickly depressurize to atmospheric pressure for foaming, cool and set to obtain biodegradable polyurethane foam with high bio-based content.

[0029] Testing experiment: Degradable polyurethane foam with high bio-based content was prepared as a sample according to each embodiment and comparative example, and the mechanical properties, resilience and degradability of the polyurethane foam were tested.

[0030] Mechanical property testing: The test was conducted in accordance with the "Determination of Tensile Strength and Elongation at Break of Porous Polymer Elastic Materials" (GB / T 10654-2001). The test conditions were uniform tension at 500 mm / min until fracture. The tensile strength and elongation at break of the test specimens were measured. Each specimen was tested 5 times, and the average value of the results was taken.

[0031] Resilience test: The test is conducted in accordance with the "Determination of Resilience Performance of Flexible Foam Polymer Materials by Falling Ball Method" (GB / T 6670-2008). The test conditions are as follows: a standard steel ball (16 mm in diameter) is dropped freely from a height of 460 mm to impact the center of the specimen. The rebound rate of the specimen is tested. Each specimen is tested 3 times, and the average value is taken.

[0032] Degradation performance test: The test was conducted in accordance with the method of determining the release of carbon dioxide for the final aerobic biodegradation capacity of materials under controlled composting conditions (GB / T 19277.1-2025). The test conditions were as follows: the mass ratio of the test inoculum to the sample mass was 6:1, with the control group containing only the test inoculum. The test period was 6 months, and the biodegradation rate of the test sample was measured.

[0033]

[0034] Conclusion: The test data shows that, compared with the comparative examples, the biodegradable high-bio-based polyurethane foam of the embodiment exhibits excellent biodegradability, exceeding 90% after 6 months of composting. No large-volume polyurethane foam was found in the compost. Comparative Examples 2 and 3, which used petroleum-based raw materials that are more difficult to decompose, had biodegradability far lower than Example 1. The biodegradable high-bio-based polyurethane foam provided by this invention possesses good mechanical properties, good resilience, and excellent degradation performance, enabling it to degrade in a composting environment and meeting the needs of sustainable development of polymer materials.

[0035] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method of producing a degradable high-bio-based content polyurethane foam, characterized by: Specifically, Step 1: castor oil-isosorbide polyepicyclic carbonate is synthesized by using isosorbide diglycidyl ether and castor oil triglycidyl ether as raw materials; Step 2: vanillin-decanediol prepolymer is synthesized by using vanillin, glycerol triglycidyl ether and decanediol as raw materials; Step 3: non-isocyanate polyurethane elastomer is synthesized by using castor oil-isosorbide polyepicyclic carbonate, vanillin-decanediol prepolymer and decanediol as raw materials, and adding silanized cellulose nanofiber, and then foaming the non-isocyanate polyurethane elastomer by using supercritical CO2 technology to obtain a degradable high-bio-based-content polyurethane foam.

2. A process for producing a degradable high-bio-based content polyurethane foam according to claim 1, characterized in that: The preparation method of the castor oil-isosorbide polyepicyclic carbonate is as follows: Isosorbide diglycidyl ether is added to castor oil triglycidyl ether, stirred at 50-60℃ and 200-300rpm for 20-30min, catalyst tetrabutylammonium bromide is added, the replacement atmosphere is carbon dioxide and the pressure is increased to 2.5-3.0MPa, the reaction is carried out at 110-120℃ and 400-500rpm for 10-12h, after the reaction is completed, it is cooled to room temperature, the pressure is released, and the castor oil-isosorbide polyepicyclic carbonate is obtained.

3. A process for producing a degradable high-bio-based content polyurethane foam according to claim 2, characterized in that: The mass ratio of isosorbide diglycidyl ether, castor oil triglycidyl ether and catalyst tetrabutylammonium bromide is (20-30):(40-50):(1.4-1.6).

4. A process for producing a degradable high-bio-based content polyurethane foam according to claim 1, characterized by: The preparation method of the vanillin-decanediol prepolymer is as follows: Vanillin is added to glycerol triglycidyl ether, stirred at 50-60℃ and 200-300rpm for 20-30min, catalyst DBU is added, the reaction is carried out at 110-120℃ and 400-500rpm for 12-16h under nitrogen protection, after the reaction is completed, it is cooled, added to ethyl acetate, washed with saturated sodium carbonate solution and deionized water in sequence, the organic phase is dried with anhydrous magnesium sulfate, after removing ethyl acetate by vacuum distillation at 50-60℃, it is added to decanediol, the reaction is carried out at 100-110℃ and 400-500rpm for 2-4h under nitrogen protection, after the reaction is completed, it is cooled, and the vanillin-decanediol prepolymer is obtained.

5. A process for producing a degradable high-bio-based content polyurethane foam according to claim 4, characterized in that: The mass ratio of vanillin, glycerol triglycidyl ether, catalyst DBU and decanediol is (37-41):(20-22):(0.6-0.7):(20-24).

6. A process for producing a degradable high-bio-based content polyurethane foam according to claim 1, characterized by: The preparation method of the non-isocyanate polyurethane elastomer is as follows: The silane modified cellulose nanofiber is added into N,N-dimethylformamide, stirred at 200-300 rpm for 20-30 min, and ultrasonically dispersed for 20-30 min to obtain a cellulose nanofiber dispersion liquid; the decanediamine and the vanillin-decanediamine prepolymer are added into N,N-dimethylformamide, stirred at 200-300 rpm for 20-30 min, and a catalyst DABCO (1,4-diazabicyclo[2.2.2]octane) is added, and the stirring is continued for 20-30 min to obtain a mixed diamine solution; the castor oil-isorobitol polycyclic carbonate is added into N,N-dimethylformamide, stirred at 90-100 ℃ under nitrogen protection and at 200-300 rpm for 20-30 min, and the cellulose nanofiber dispersion liquid is added, and the stirring is continued for 20-30 min; the mixed diamine solution is added dropwise under the condition of 90-100 ℃ and 200-300 rpm, and the reaction is carried out for 10-14 h, and after the reaction is completed, the reaction system is cooled to room temperature, and then added into deionized water for precipitation, filtered, washed with methanol, and vacuum dried at 60-70 ℃ for 16-20 h to obtain a non-isocyanate type polyurethane elastomer.

7. A process for producing a degradable high-bio-based content polyurethane foam according to claim 6, characterized in that: The mass ratio of the silane modified cellulose nanofiber, the decanediamine, the vanillin-decanediamine prepolymer, the castor oil-isorobitol polycyclic carbonate and the catalyst DABCO is (20-40):(130-150):(40-60):(500-520):(5-7).

8. The method of producing a degradable, high-bio-based content polyurethane foam according to claim 1, characterized in that: The preparation method of the silane modified nanocellulose fiber is as follows: The cellulose nanofiber is added into deionized water, stirred at 30-40 ℃ and at 200-300 rpm for 20-30 min, and ultrasonically dispersed for 20-30 min, and then the pH is adjusted to 4-5, and a silane coupling agent KH-550 is added, and the reaction is carried out at 60-70 ℃ and at 400-500 rpm for 6-8 h, and after the reaction is completed, the reaction system is cooled, washed with ethanol and deionized water, and vacuum dried at 70-80 ℃ for 4-6 h to obtain the silane modified cellulose nanofiber. The mass ratio of the cellulose nanofiber and the silane coupling agent KH-550 is (30-50):(3-4).

9. The process for producing a degradable high-bio-based content polyurethane foam according to claim 1, characterized in that: The preparation method of the degradable high-bio-based content polyurethane foam is as follows: The non-isocyanate type polyurethane elastomer is placed into a foaming cavity of an autoclave, carbon dioxide is used to replace the gas in the autoclave, and then the temperature is increased to 140-150 ℃, carbon dioxide is introduced to increase the pressure in the autoclave to 8-12 MPa, and after the temperature and pressure are maintained for 0.5-1.5 h, the pressure is rapidly released to normal pressure to foam, and the foam is cooled and shaped to obtain the degradable high-bio-based content polyurethane foam.

10. A degradable high-bio-based content polyurethane foam characterized by: The production method according to any one of claims 1-9. The production method according to any one of claims 1-9.

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