Elastic waterproof biomimetic membrane as well as preparation method and application thereof

Abstract

The invention relates to the technical field of polyurethane, and discloses an elastic waterproof biomimetic membrane as well as a preparation method and application thereof. Polylactic acid dihydric alcohol, an isocyanate monomer, a chain extender and cardanol siloxane-based cellulose are subjected to a polymerization chain extension reaction, and the elastic waterproof biomimetic membrane is obtained. The nano cellulose containing a benzene ring structure, a cardanol flexible long carbon chain and a siloxane structure are introduced into polyurethane, so that the tensile strength and the elongation at break of a polyurethane film are improved. Meanwhile, the hydrophilicity of cellulose is reduced, the water contact angle of the polyurethane film is increased, the waterproof performance is enhanced, and the good practical application is achieved in the waterproof finishing aspect of fabric such as bionic waterproof and moisture permeable films and outdoor jackets.

Description

Technical Field

[0001] This invention relates to the field of polyurethane technology, specifically to an elastic waterproof biomimetic membrane, its preparation method, and its application. Background Technology

[0002] Polyurethane possesses excellent elasticity, high adhesion, and good weather resistance, making it suitable as a finishing agent, membrane material, and coating. It has wide applications in fabric finishing and waterproof / breathable membranes. However, the hydrophilic nature of polyurethane finishing agents typically limits its use in waterproof fabric finishing. Polylactic acid (PLA) exhibits excellent biocompatibility and biodegradability, and can be used as a polyester diol to prepare biomimetic polyester polyurethanes. Traditional polyester polyurethanes are prone to water absorption and decomposition, resulting in poor water resistance and waterproofing.

[0003] Nanocellulose is biocompatible, inexpensive, readily available, and environmentally friendly, making it important for applications in polymer materials such as polyurethane. Chinese patent CN108951164B discloses a flame-retardant finishing agent for pure cotton fabrics and its preparation method. Using polyurethane emulsion, flame-retardant synergists, and hydroxymethyl cellulose as raw materials, the prepared flame-retardant finishing agent can improve the flame-retardant properties of cotton fabrics. However, the polyurethane finishing agent in this patent cannot provide waterproofing for the fabric. Summary of the Invention

[0004] In view of the shortcomings of existing technologies and the waterproof and heat-insulating properties of the skin of bear mammals, this invention provides an elastic waterproof biomimetic membrane, its preparation method and application, which solves the problem of poor waterproof performance of polyurethane finishing agents.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing an elastic waterproof biomimetic membrane. Furthermore, the preparation method of cashew siloxane cellulose includes: (1) Water, sodium hydroxide, and nanocellulose were added to a reaction vessel. After stirring, ethanol, 2,2-bis(4-epoxypropoxyphenyl)propane (CAS Registry No. 1675-54-3), and cashew phenol were added. After the reaction, ethanol was added to dilute the mixture. The mixture was filtered, washed with water and ethanol, and dried to obtain cashew phenol-based cellulose. The reaction formula is: .

[0006] (2) Add isopropanol and cashew cellulose to the reaction vessel, stir, add bis(trimethylsiloxymethylsilane) (CAS Registry No. 1873-88-7), add chloroplatinic acid-isopropanol solution dropwise, pass nitrogen gas through, filter after reaction, wash with ethanol, dry, and obtain cashew cellulose.

[0007] (3) Add the dried and dehydrated polylactic acid diol and isocyanate monomer to the reaction vessel, heat to the reaction temperature, carry out the prepolymerization reaction, and then add dibutyltin dilaurate, chain extender, cashew phenol siloxane cellulose and N,N-dimethylformamide solvent, continue the reaction, pour the solution into the mold to cast the film, degas under vacuum, dry, and obtain an elastic waterproof biomimetic film.

[0008] Furthermore, in (1), the ratio of nanocellulose, 2,2-bis(4-epoxypropoxyphenyl)propane, and cashew phenol is 100g:(50-120)g:(45-110)g.

[0009] Furthermore, in (1), the reaction temperature is 60-75℃ and the reaction time is 5-8h.

[0010] Furthermore, in (2), the mass ratio of cashew phenolic cellulose and bis(trimethylsiloxymethylsilane) is 100:(20-50).

[0011] Furthermore, in (2), the reaction temperature is 80-85℃ and the reaction time is 12-18h.

[0012] Furthermore, in (3), the reaction temperature is 70-80℃, the prepolymerization reaction time is 2-3.5h, and the reaction time is 1-2h.

[0013] Furthermore, in (3), the ratio of polylactic acid diol, isocyanate monomer, dibutyltin dilaurate, chain extender, and cashew siloxane cellulose is 1 mol: (2.6-3) mol: (0.005-0.007) mol: (1-1.3) mol: (150-400) g.

[0014] Furthermore, in (3), the isocyanate monomer is isophorone diisocyanate or toluene diisocyanate.

[0015] Furthermore, the chain extender in (3) includes 1,4-butanediol, 1,6-hexanediol or diethylene glycol.

[0016] Furthermore, elastic waterproof biomimetic membranes are applied in the finishing of fabrics.

[0017] The beneficial technical effects of this invention are as follows: using 2,2-bis(4-epoxypropoxyphenyl)propane as a crosslinking agent, the epoxy groups undergo ring-opening reactions with the hydroxyl groups of nanocellulose and cashew phenol to obtain cashew phenol-based cellulose containing hydroxyl groups and multiple benzene rings. Then, the alkenyl group of cashew phenol undergoes an addition reaction with the Si-H bond of bis(trimethylsiloxymethylsilane) to obtain cashew phenol siloxane cellulose. The hydroxyl groups generated by the ring-opening reaction of nanocellulose undergo a polymerization and chain extension reaction with polylactic acid diol and isocyanate monomers to obtain an elastic waterproof biomimetic membrane.

[0018] This invention introduces nanocellulose containing a large number of benzene ring structures, flexible long carbon chains of cashew phenol, and siloxane structures into polyurethane. The nanocellulose and benzene ring structures possess high rigidity, which is beneficial for improving the strength of the polyurethane membrane. The long carbon chains and flexible siloxane structures can endow the membrane material with excellent toughness and elasticity, thereby improving tensile strength and elongation at break. The polyurethane contains polylactic acid segments, exhibiting good biocompatibility, skin affinity, and unique biomimetic effects.

[0019] The nanocellulose of this invention introduces a large number of hydrophobic benzene rings, long carbon chains and siloxane structures, which reduces the hydrophilicity of cellulose, increases the water contact angle of the polyurethane membrane, and enhances the waterproof performance. It has good practical applications in waterproof finishing of fabrics such as rain jackets, and the elastic biomimetic membrane can give the fabric good elasticity, biomimetic and other properties.

[0020] The polyurethane of this invention can also be molded into porous membranes using dry, wet, and phase inversion methods, exhibiting both waterproof and breathable properties, and has broad application prospects in waterproof and breathable membranes. The prepared membrane material can be used alone and possesses good elasticity, waterproofness, and biomimetic properties. Detailed Implementation

[0021] The following nanocellulose, model NFC-33L2, is from Jinan Shengquan Group Co., Ltd. The polylactic acid diol, with an average molecular weight of approximately 2000, is from Wuhan Kangqiong Biomedical Technology Co., Ltd.

[0022] Example 1: (1) Add 1L of water, 36g of sodium hydroxide and 20g of nanocellulose to the reaction vessel, stir and then add 200mL of ethanol, 10g of 2,2-bis(4-epoxypropoxyphenyl)propane and 9g of cashew phenol, heat to 65℃ and react for 6h. After the reaction, add ethanol to dilute, filter and wash with water and ethanol, and dry to obtain cashew phenol-based cellulose.

[0023] (2) Add 2L of isopropanol and 30g of cashew cellulose to the reaction vessel, stir, add 6g of bistrimethylsiloxymethylsilane, add 3mL of chloroplatinic acid-isopropanol solution, purge with nitrogen, heat to 80℃, stir and reflux for 18h, filter, wash with ethanol, dry to obtain cashew cellulose.

[0024] (3) 203g (about 0.1mol) of dried and dehydrated polylactic acid diol and 0.3mol of toluene diisocyanate were added to the reaction vessel and heated to 70°C for 3.5h of prepolymerization. Then, 0.5mmol of dibutyltin dilaurate, 0.13mol of 1,4-butanediol, 15g of cashew siloxane cellulose and 300mL of N,N-dimethylformamide solvent were added and reacted for 1h. The solution was poured into a mold to cast into a film, degassed under vacuum, and dried to obtain an elastic waterproof biomimetic film.

[0025] Example 2: (1) Add 1.5L of water, 30g of sodium hydroxide and 20g of nanocellulose to the reaction vessel, stir and then add 250mL of ethanol, 18g of 2,2-bis(4-epoxypropoxyphenyl)propane and 16g of cashew phenol, heat to 60℃ and react for 8h. After the reaction, add ethanol to dilute, filter and wash with water and ethanol, and dry to obtain cashew phenol-based cellulose.

[0026] (2) Add 2.5L isopropanol and 30g cashew cellulose to the reaction vessel, stir, add 10g bistrimethylsiloxymethylsilane, add 6mL of chloroplatinic acid-isopropanol solution, purge with nitrogen, heat to 85℃, stir and reflux for 12h, filter, wash with ethanol, and dry to obtain cashew siloxane cellulose.

[0027] (3) Add 0.1 mol of dried polylactic acid diol and 0.28 mol of isophorone diisocyanate to the reaction vessel, heat to 70°C, and prepolymerize for 3 h. Then add 0.7 mmol of dibutyltin dilaurate, 0.12 mol of diethylene glycol, 25 g of cashew siloxane cellulose and 400 mL of N,N-dimethylformamide solvent, and react for 2 h. Pour the solution into a mold to cast into a film, degas under vacuum, and dry to obtain an elastic waterproof biomimetic film.

[0028] Example 3: (1) Add 1.5L of water, 40g of sodium hydroxide and 20g of nanocellulose to the reaction vessel, stir and then add 300mL of ethanol, 24g of 2,2-bis(4-epoxypropoxyphenyl)propane and 22g of cashew phenol, heat to 75℃ and react for 5h. After the reaction, add ethanol to dilute, filter and wash with water and ethanol, and dry to obtain cashew phenol-based cellulose.

[0029] (2) Add 3L of isopropanol and 30g of cashew cellulose to the reaction vessel, stir, add 15g of bis(trimethylsiloxymethylsilane), add 8mL of chloroplatinic acid-isopropanol solution, purge with nitrogen, heat to 80°C, stir and reflux for 18h, filter, wash with ethanol, and dry to obtain cashew cellulose.

[0030] (3) Add 0.1 mol of dried polylactic acid diol and 0.26 mol of toluene diisocyanate to the reaction vessel, heat to 80°C, and prepolymerize for 2 h. Then add 0.6 mmol of dibutyltin dilaurate, 0.1 mol of 1,6-hexanediol, 40 g of cashew siloxane cellulose and 400 mL of N,N-dimethylformamide solvent, react for 2 h, pour the solution into a mold to cast into a film, degas under vacuum, and dry to obtain an elastic waterproof biomimetic film.

[0031] Comparative Example 1 differs from Example 1 in that nanocellulose is used instead of cashew siloxane cellulose.

[0032] (1) 0.1 mol of dried polylactic acid diol and 0.3 mol of toluene diisocyanate were added to the reaction vessel and heated to 70°C for 3.5 h of prepolymerization. Then, 0.5 mmol of dibutyltin dilaurate, 0.13 mol of 1,4-butanediol, 15 g of nanocellulose and 300 mL of N,N-dimethylformamide solvent were added and reacted for 1 h. The solution was poured into a mold to cast into a film, degassed under vacuum, and dried to obtain a biomimetic film.

[0033] Comparative Example 2 differs from Example 1 in that cashew phenol-based cellulose is used instead of cashew phenol siloxane cellulose.

[0034] (1) 0.1 mol of dried polylactic acid diol and 0.3 mol of toluene diisocyanate were added to the reaction vessel and heated to 70°C for 3.5 h of prepolymerization. Then, 0.5 mmol of dibutyltin dilaurate, 0.13 mol of 1,4-butanediol, 15 g of cashew phenolic cellulose and 300 mL of N,N-dimethylformamide solvent were added and reacted for 1 h. The solution was poured into a mold to cast into a film, degassed under vacuum, and dried to obtain a biomimetic film.

[0035] Comparative Example 3 differs from Example 1 in that ethylene glycol diglycidyl ether is used instead of 2,2-bis(4-epoxypropoxyphenyl)propane.

[0036] (1) Add 1L of water, 36g of sodium hydroxide, and 20g of nanocellulose to the reaction vessel. After stirring, add 200mL of ethanol, 10g of ethylene glycol diglycidyl ether, and 9g of cashew phenol. Heat to 65℃ and react for 6h. After the reaction, add ethanol to dilute. After filtration, wash with water and ethanol and dry to obtain cashew phenol-based cellulose.

[0037] (2) Add 2L of isopropanol and 30g of cashew cellulose to the reaction vessel, stir, add 6g of bistrimethylsiloxymethylsilane, add 3mL of chloroplatinic acid-isopropanol solution, purge with nitrogen, heat to 80℃, stir and reflux for 18h, filter, wash with ethanol, dry to obtain cashew cellulose.

[0038] (3) Add 0.1 mol of dried polylactic acid diol and 0.3 mol of toluene diisocyanate to the reaction vessel, heat to 70°C, and prepolymerize for 3.5 h. Then add 0.5 mmol of dibutyltin dilaurate, 0.13 mol of 1,4-butanediol, 15 g of cashew siloxane cellulose and 300 mL of N,N-dimethylformamide solvent, react for 1 h, pour the solution into a mold to cast into a film, degas under vacuum, and dry to obtain a biomimetic film.

[0039] Comparative Example 4 differs from Example 1 in that octadecyltrichlorosilane was used to hydrophobically modify the nanocellulose.

[0040] (1) Add 1L of n-hexane, 20g of nanocellulose and 9g of octadecyltrichlorosilane to the reaction vessel, react for 6h, filter, wash with ethanol and dry to obtain octadecylsiloxane cellulose.

[0041] (2) 0.1 mol of dried polylactic acid diol and 0.3 mol of toluene diisocyanate were added to the reaction vessel and heated to 70°C for 3.5 h of prepolymerization. Then, 0.5 mmol of dibutyltin dilaurate, 0.13 mol of 1,4-butanediol, 15 g of octadecylsiloxane cellulose and 300 mL of N,N-dimethylformamide solvent were added and reacted for 1 h. The solution was poured into a mold to cast into a film, degassed under vacuum, and dried to obtain a biomimetic film.

[0042] Comparative Example 5 differs from Example 1 in that 1-octadecyl alcohol is used instead of cashew phenol.

[0043] (1) Add 1L of water, 36g of sodium hydroxide and 20g of nanocellulose to the reaction vessel, stir and then add 200mL of ethanol, 10g of 2,2-bis(4-epoxypropoxyphenyl)propane and 9g of 1-octadecyl alcohol, heat to 65℃ and react for 6h. After the reaction, add ethanol to dilute, filter and wash with water and ethanol, and dry to obtain octadecyl cellulose.

[0044] (2) Add 2L of isopropanol and 30g of octadecyl cellulose (without alkenyl group) to the reaction vessel, stir, add 6g of bis(trimethylsiloxymethylsilane), add 3mL of solution containing 0.05mg chloroplatinic acid-isopropanol, purge with nitrogen, heat to 80℃, stir, reflux for 18h, filter, wash with ethanol, dry, and obtain octadecyl cellulose.

[0045] (3) Add 0.1 mol of dried polylactic acid diol and 0.3 mol of toluene diisocyanate to the reaction vessel, heat to 70°C, and prepolymerize for 3.5 h. Then add 0.5 mmol of dibutyltin dilaurate, 0.13 mol of 1,4-butanediol, 15 g of octadecyl cellulose and 300 mL of N,N-dimethylformamide solvent, react for 1 h, pour the solution into a mold to cast into a film, degas under vacuum, and dry to obtain a biomimetic film.

[0046] The tensile properties of the membrane material were tested according to GB / T 1040.3-2006. The water contact angle was tested according to GB / T 30693-2014.

[0047] Table 1 Performance Tests

[0048] The polyurethane membrane materials in each embodiment possess both good tensile strength and elongation at break, as well as a large water contact angle and good waterproof performance. This is mainly due to the addition of cashew phenol siloxane cellulose for polymerization and chain extension reaction. This introduces nanocellulose containing a large number of benzene ring structures, flexible long carbon chains of cashew phenol, and siloxane structures into the polyurethane. The nanocellulose and benzene ring structures have high rigidity, which is beneficial to improving the strength of the polyurethane membrane. The long carbon chains and flexible siloxane structures can endow the membrane material with excellent toughness and elasticity, thereby improving tensile strength and elongation at break. Furthermore, the introduction of a large number of hydrophobic benzene rings, long carbon chains, and siloxane structures into cellulose reduces the hydrophilicity of cellulose, thereby increasing the water contact angle of the polyurethane membrane and improving its waterproof performance.

[0049] Compared with Example 1, Comparative Example 1 only added nanocellulose, resulting in polyurethane with low elongation at break, low flexibility and elasticity, low water contact angle, and poor waterproof performance.

[0050] Comparative Example 2, which added cashew phenolic cellulose, did not contain a siloxane structure, resulting in a polyurethane film with low elongation at break and water contact angle, poor flexibility and elasticity, and poor waterproof performance.

[0051] Comparative Example 3 used ethylene glycol diglycidyl ether, which does not contain phenyl groups, instead of 2,2-bis(4-epoxypropoxyphenyl)propane. The tensile strength and water contact angle of the polyurethane membrane material were significantly lower.

[0052] In Comparative Example 4, the silane-chloroalkali of octadecyltrichlorosilane was reacted with the hydroxyl groups of nanocellulose to achieve hydrophobic modification of cellulose. However, most of the hydroxyl groups of cellulose were reacted, which prevented the nanocellulose from participating well in the chain extension polymerization reaction of polyurethane, which seriously affected the tensile strength of the membrane material. Furthermore, the modified cellulose did not contain a large number of benzene ring structures, so it could not improve the strength and water contact angle of the polyurethane membrane.

[0053] The octadecyl alcohol in Comparative Example 5 and the octadecyl cellulose prepared therefrom do not contain alkenyl groups and cannot undergo hydrosilylation reaction with bis(trimethylsiloxymethylsilane). After washing with ethanol, bis(trimethylsiloxymethylsilane) is washed away from the cellulose matrix. No siloxane structure is introduced into the cellulose matrix, resulting in significantly lower elongation at break and water contact angle of the cellulose.

Claims

1. A method for preparing an elastic, waterproof, biomimetic membrane, characterized in that, The preparation method includes: adding dried and dehydrated polylactic acid diol and isocyanate monomer to a reaction vessel, heating to the reaction temperature, carrying out a prepolymerization reaction, then adding dibutyltin dilaurate, chain extender, cashew phenol siloxane cellulose, and N,N-dimethylformamide solvent, continuing the reaction, pouring the solution into a mold to cast into a film, vacuum degassing, and drying to obtain an elastic waterproof biomimetic film.

2. The method for preparing the elastic waterproof biomimetic membrane according to claim 1, characterized in that, The reaction temperature is 70-80℃, the prepolymerization reaction time is 2-3.5h, and the reaction time is 1-2h.

3. The method for preparing the elastic waterproof biomimetic membrane according to claim 1, characterized in that, The ratio of polylactic acid diol, isocyanate monomer, dibutyltin dilaurate, chain extender, and cashew siloxane cellulose is 1 mol: (2.6-3) mol: (0.005-0.007) mol: (1-1.3) mol: (150-400) g.

4. The method for preparing the elastic waterproof biomimetic membrane according to claim 3, characterized in that, The isocyanate monomer is isophorone diisocyanate or toluene diisocyanate.

5. The method for preparing the elastic waterproof biomimetic membrane according to claim 3, characterized in that, The chain extender includes 1,4-butanediol, 1,6-hexanediol, or diethylene glycol.

6. The method for preparing the elastic waterproof biomimetic membrane according to claim 3, characterized in that, The method for preparing the cashew siloxane cellulose includes: (1) Add water, sodium hydroxide and nanocellulose to the reaction vessel, stir and then add ethanol, 2,2-bis(4-epoxypropoxyphenyl)propane and cashew phenol, heat to 60-75℃, stir and react for 5-8h, add ethanol to dilute, filter and wash, dry to obtain cashew phenol-based cellulose. (2) Add isopropanol and cashew cellulose to the reaction vessel, stir, add bis(trimethylsiloxymethylsilane), add chloroplatinic acid-isopropanol solution, purge with nitrogen, heat to 80-85℃, stir and reflux for 12-18h, filter, wash and dry to obtain cashew cellulose.

7. The method for preparing the elastic waterproof biomimetic membrane according to claim 6, characterized in that, The ratio of nanocellulose, 2,2-bis(4-epoxypropoxyphenyl)propane, and cashew phenol is 100g:(50-120)g:(45-110)g.

8. The method for preparing the elastic waterproof biomimetic membrane according to claim 6, characterized in that, The mass ratio of cashew phenolic cellulose to bis(trimethylsiloxymethylsilane) is 100:(20-50).

9. An elastic waterproof biomimetic membrane obtained by the preparation method according to any one of claims 1-8.

10. The application of the elastic waterproof biomimetic membrane as described in claim 9 in the finishing of fabrics.

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