High gloss waterborne polyurethane and method for preparing the same

Abstract

The application discloses a high-gloss water-based polyurethane and a preparation method thereof, and relates to the polyurethane field.The high-gloss water-based polyurethane comprises the following raw materials in parts by weight: isophorone diisocyanate 19-26 parts; polybutylene adipate 24-32 parts; a catalyst 0.1-0.3 parts; a hydrophilic chain extender 3.5-5 parts; lignin 1.7-2.6 parts; konjac gum 2.3-2.9 parts; a hydroxyl-terminated hyperbranched polymer 11-16 parts; deionized water 65-80 parts; and wherein the preparation method of the lignin is mixing industrial lignin and an organic solvent, stirring at 30-50 DEG C for 5-7 h, filtering and separating, evaporating the organic solvent from the filtrate, and drying to obtain the lignin.The high-gloss water-based polyurethane prepared by the application can meet the high-gloss requirement of water-based polyurethane as a leather finishing agent raw material after film formation.

Description

Technical Field

[0001] This invention relates to the field of polyurethane, and in particular to a high-gloss waterborne polyurethane and its preparation method. Background Technology

[0002] Waterborne polyurethane is a novel polyurethane system that uses water instead of organic solvents as the dispersion medium. While retaining some of the advantages of traditional solvent-based polyurethane materials, such as high physical and mechanical strength and good wear resistance, it reduces the release of volatile organic compounds (VOCs). Waterborne polyurethane is environmentally friendly, has low toxicity, and good compatibility, and is widely used in coatings, adhesives, leather finishing agents, and fabric finishing agents.

[0003] Leather finishing agents are a general term for a class of leather auxiliaries used to coat, protect, and beautify the surface of leather. They are mainly composed of film-forming substances, coloring materials, solvents, and auxiliaries formulated in a certain proportion, with the film-forming substance being the foundation of the leather finishing agent. Waterborne polyurethane has good film-forming properties and mechanical properties, and can be used as a film-forming substance in leather finishing agents.

[0004] Currently, most waterborne polyurethanes are prepared using polycarbonate diols, polyether diols, polyester diols, etc. as polyol raw materials and diisocyanates as raw materials. After film formation, the gloss is poor and cannot meet the optical and aesthetic requirements of leather. Summary of the Invention

[0005] In order to meet the high gloss requirement of waterborne polyurethane as a raw material for leather finishing agent after film formation, this application provides a high-gloss waterborne polyurethane and its preparation method.

[0006] This application provides a high-gloss waterborne polyurethane and its preparation method, which adopts the following technical solution: In a first aspect, this application discloses a high-gloss waterborne polyurethane, comprising the following raw materials in parts by weight: 19-26 parts of isophorone diisocyanate; 24-32 parts of polybutylene adipate; Catalyst 0.1-0.3 parts; 3.5-5 parts of hydrophilic chain extender; Lignin 1.7-2.6 parts; 2.3-2.9 parts konjac gum; 11-16 parts of hydroxyl-terminated hyperbranched polymer; 65-80 parts deionized water; The preparation method of lignin is to mix industrial lignin with an organic solvent, stir at 30-50℃ for 5-7 hours, filter and separate, evaporate the filtrate to remove the organic solvent, and then dry it to obtain the lignin.

[0007] By adopting the above technical solution, specific types of diisocyanates and polyols with high gloss were selected in the raw materials for preparing waterborne polyurethane. Lignin and konjac gum were added to modify the polyurethane. Both lignin and konjac gum have abundant hydroxyl groups, which can be crosslinked into the polyurethane network through the reaction with -NCO, thereby improving the degree of crosslinking of waterborne polyurethane. Furthermore, the good film-forming properties of lignin and konjac gum themselves improve the gloss, water resistance, and dry and wet rubbing resistance of waterborne polyurethane. By adding end-hydroxyl hyperbranched polymers and crosslinking them with the polyurethane system to form an interpenetrating network, the leveling properties of the system are improved, making the surface of the coating structure smoother, thereby improving gloss and simultaneously enhancing adhesion and bonding strength with leather surfaces.

[0008] Optionally, the terminal hydroxyl hyperbranched polymer is selected from one or more of Boltorn H2004, Boltorn P500, HyPerH10, and HyPer H40.

[0009] By adopting the above technical solution, the selected end-hydroxyl hyperbranched polymer has high reactivity and excellent film-forming properties. After crosslinking with the polyurethane system, the resulting coating film has high gloss and strong adhesion.

[0010] Optionally, the industrial lignin is selected from at least one of alkali lignin and enzymatically hydrolyzed lignin, and the organic solvent is selected from at least one of tetrahydrofuran, acetone, and isopropanol, and the mixed concentration of the industrial lignin and the organic solvent is 200-500 g / L.

[0011] By adopting the above technical solution and treating industrial lignin with organic solvents, the molecular weight of lignin is reduced, thereby improving the reactivity and hydroxyl content of lignin and enhancing the compatibility between lignin and polyurethane systems.

[0012] Optionally, the lignin is nitrated modified lignin, which has a nitrogen content of 5%-8% and comprises the following raw materials in parts by weight: 20-24 parts of lignin; 48-53 parts of fuming nitric acid; Acetic anhydride 24-27 parts.

[0013] By adopting the above technical solution, fuming nitric acid and acetic anhydride are used to nitrate and modify lignin, introducing nitrogen-containing functional groups such as nitro groups. This makes the modified lignin more compatible with the waterborne polyurethane system, and further increases the crosslinking density, making the coating structure more compact, which is beneficial to improving the water resistance and gloss of the coating.

[0014] Optionally, the hydroxyl-terminated hyperbranched polymer is a partially modified hydroxyl-terminated hyperbranched polymer, comprising the following raw materials in parts by weight: 24-28 parts of hydroxyl-terminated hyperbranched polymer; Perfluorooctanoic acid chloride 13-17 parts.

[0015] By adopting the above technical solution, fluorine is introduced into the end part of the hyperbranched polymer through the reaction of perfluorooctanoic acid chloride and terminal hydroxyl groups. The introduction of fluorine makes the crosslinked waterborne polyurethane have good water resistance and strong chemical stability.

[0016] Optionally, the catalyst may be at least one of dibutyltin dilaurate or an organobismuth catalyst.

[0017] Optionally, the hydrophilic chain extender may be selected from at least one of dimethylolbutyric acid, dimethylolpropionic acid, and 1,2-butanediol.

[0018] Secondly, this application discloses a method for preparing high-gloss waterborne polyurethane, comprising the following steps: Preparation of polyurethane prepolymer: Polybutylene adipate was vacuum dehydrated and cooled for later use. Polybutylene adipate and isophorone diisocyanate were added to a three-necked flask, along with a catalyst and acetone solvent. The mixture was heated to 78-80℃ and reacted for 2-2.5 h. A hydrophilic chain extender was added and the mixture was reacted at 55-60℃ for 1-1.5 h. Lignin and konjac gum were then added and reacted for 30-40 min. Acetone was added to adjust the viscosity to obtain the polyurethane prepolymer. Synthesis of hyperbranched polyurethane: Add hydroxyl-terminated hyperbranched polymer to polyurethane prepolymer, heat to 80-83℃ and react until the hydroxyl content of the system is 0 to obtain hyperbranched polyurethane; Post-processing: Cool the hyperbranched polyurethane to 30-40℃, add the neutralizing agent triethylamine and react for 30-35 minutes, finally add deionized water for high-speed dispersion and emulsification, and remove acetone under vacuum to obtain high-gloss waterborne polyurethane.

[0019] By adopting the above technical solution, waterborne polyurethane is synthesized using the prepolymer method. The preparation method is simple and suitable for industrialization.

[0020] Optionally, when nitrated lignin is selected as the lignin, the nitrated lignin is prepared by the following method: After mixing lignin and fuming nitric acid, acetic anhydride was added dropwise, and the mixture was stirred in an ice-salt bath for 12-18 hours. The resulting solid precipitate was then repeatedly washed with ice water and subjected to ultracentrifugation to obtain nitrated modified lignin.

[0021] Optionally, when a partially modified hydroxyl-terminated hyperbranched polymer is selected as the terminal hydroxyl hyperbranched polymer, the partially modified hydroxyl-terminated hyperbranched polymer is prepared by the following method: A pyridine solution of the hydroxyl-terminated hyperbranched polymer was added to a flask and heated to 25-35°C. Under nitrogen protection, perfluorooctanoic acid chloride was added dropwise with stirring. After the addition was complete, the mixture was heated to 50-70°C and reacted for 3-4 hours. The pyridine and another product, hydrogen chloride, were removed by vacuum. The mixture was then repeatedly washed with toluene and deionized water and dried under vacuum to obtain the partially modified hydroxyl-terminated hyperbranched polymer.

[0022] In summary, this application has at least one of the following beneficial effects: 1. In the preparation of waterborne polyurethane, specific types of diisocyanates and polyols with high gloss were selected. Lignin and konjac gum were added to modify the polyurethane. Both lignin and konjac gum are rich in hydroxyl groups, which crosslink into the polyurethane network through the reaction with -NCO, thereby improving the degree of crosslinking of the waterborne polyurethane. Furthermore, the good film-forming properties of lignin and konjac gum themselves enhance the gloss, water resistance, and dry and wet rubbing resistance of the waterborne polyurethane. By adding end-hydroxyl hyperbranched polymers and crosslinking them with the polyurethane system to form an interpenetrating network, the leveling properties of the system are improved, resulting in a smoother surface of the coating structure, thereby improving gloss and simultaneously enhancing adhesion and bonding strength with leather surfaces.

[0023] 2. Nitrification modification of lignin is carried out using fuming nitric acid and acetic anhydride, introducing nitrogen-containing functional groups such as nitro groups. This makes the modified lignin more compatible with the waterborne polyurethane system and further increases the crosslinking density, making the coating structure more compact, which is beneficial to improving the water resistance and gloss of the coating. Detailed Implementation

[0024] The following describes the present application in further detail with reference to the waterborne polyurethanes prepared in Examples 1-8 and Comparative Examples 1-2.

[0025] Preparation Example

[0026] Preparation Example 1 Preparation of nitrated modified lignin Nitrogen-modified lignin has a nitrogen content of 5%-8% and includes the following raw materials: 20g of lignin was obtained by mixing alkali lignin and tetrahydrofuran at a concentration of 200g / L, stirring at 30℃ for 7h, filtering and separating, evaporating the filtrate to remove the organic solvent, and drying. 48g of fuming nitric acid was purchased from Guangdong Daxiao Chemical Co., Ltd. Acetic anhydride 24g, purchased from Guangdong Daxiao Chemical Co., Ltd.

[0027] Nitrogenized lignin was prepared by the following method: The mixture of lignin and fuming nitric acid was followed by the addition of acetic anhydride, and the mixture was stirred in an ice-salt bath for 12 hours to carry out the reaction. The resulting solid precipitate was repeatedly washed with ice water and then subjected to ultracentrifugation to obtain nitrated modified lignin.

[0028] Preparation Example 2 Preparation of nitrated modified lignin Nitrogen-modified lignin has a nitrogen content of 5%-8% and includes the following raw materials: 24g of lignin was obtained by mixing alkali lignin and isopropanol at a concentration of 500g / L, stirring at 50℃ for 5h, filtering and separating, evaporating the filtrate to remove the organic solvent, and drying. 53g of fuming nitric acid was purchased from Guangdong Daxiao Chemical Co., Ltd. Acetic anhydride 27g, purchased from Guangdong Daxiao Chemical Co., Ltd.

[0029] Nitrogenized lignin was prepared by the following method: The mixture of lignin and fuming nitric acid was followed by the addition of acetic anhydride, and the mixture was stirred in an ice-salt bath for 18 hours to carry out the reaction. The resulting solid precipitate was repeatedly washed with ice water and then subjected to ultracentrifugation to obtain nitrated modified lignin.

[0030] Preparation Example 3 Preparation of partially modified hydroxyl-terminated hyperbranched polymers Partially modified hydroxyl-terminated hyperbranched polymers, including the following raw materials: 24g of hydroxyl-terminated hyperbranched polymer was purchased from Shanghai Huicheng Biotechnology Co., Ltd., with the brand name BoltornH2004. 13g of perfluorooctanoyl chloride was purchased from Shanghai Baishun Biotechnology Co., Ltd., CAS No. 335-64-8.

[0031] Partially modified hydroxyl-terminated hyperbranched polymers were prepared by the following method: A pyridine solution of the hydroxyl-terminated hyperbranched polymer was added to a flask and heated to 25°C. Perfluorooctanoic acid chloride was added dropwise under nitrogen protection with stirring. After the addition was complete, the mixture was heated to 50°C and reacted for 3 hours. The pyridine and another product, hydrogen chloride, were removed by vacuum. The mixture was repeatedly washed with toluene and deionized water and then dried under vacuum to obtain the partially modified hydroxyl-terminated hyperbranched polymer.

[0032] Preparation Example 4 Preparation of partially modified hydroxyl-terminated hyperbranched polymers Partially modified hydroxyl-terminated hyperbranched polymers, including the following raw materials: 28g of hydroxyl-terminated hyperbranched polymer was purchased from Wuhan Hyperbranched Resin Technology Co., Ltd., with the brand name HyPer H10. 17g of perfluorooctanoyl chloride was purchased from Shanghai Baishun Biotechnology Co., Ltd., CAS No. 335-64-8.

[0033] Partially modified hydroxyl-terminated hyperbranched polymers were prepared by the following method: A pyridine solution of the hydroxyl-terminated hyperbranched polymer was added to a flask and heated to 35°C. Perfluorooctanoic acid chloride was added dropwise under nitrogen protection with stirring. After the addition was complete, the mixture was heated to 70°C and reacted for 4 hours. The pyridine and another product, hydrogen chloride, were removed by vacuum. The mixture was repeatedly washed with toluene and deionized water and then dried under vacuum to obtain the partially modified hydroxyl-terminated hyperbranched polymer. Example

[0034] Example 1 A high-gloss waterborne polyurethane comprises the following raw materials: 19g of isophorone diisocyanate; Polybutylene adipate 24g; Catalyst 0.1g, specifically dibutyltin dilaurate; 3.5g of hydrophilic chain extender, specifically dimethylolbutyric acid; 1.7g of lignin was obtained by mixing enzymatically hydrolyzed lignin with isopropanol at a concentration of 200g / L, stirring at 30℃ for 7h, filtering and separating, evaporating the filtrate to remove the organic solvent, and drying. Konjac gum 2.3g; 11g of hydroxyl-terminated hyperbranched polymer was purchased from Shanghai Huicheng Biotechnology Co., Ltd., with the brand name BoltornH2004. 65g of deionized water.

[0035] High-gloss waterborne polyurethane is prepared through the following steps: Preparation of polyurethane prepolymer: Polybutylene adipate was placed in a 500mL three-necked flask equipped with a stirrer and heated. After most of the material melted, stirring was started, the temperature was raised and a vacuum was drawn. The prepolymer was dehydrated at 105℃ and a vacuum of 0.08MPa for 2 hours, and then cooled to below 50℃ and stored in a dry container for later use. Polybutylene adipate and isophorone diisocyanate were added to a three-necked flask, along with a catalyst and acetone solvent. The mixture was heated to 78°C and reacted for 2 hours. A hydrophilic chain extender was added and the mixture was reacted at 55°C for 1 hour. Lignin and konjac gum were then added and reacted for 30 minutes. Acetone solvent was added to adjust the viscosity to obtain a polyurethane prepolymer. Synthesis of hyperbranched polyurethane: A hydroxyl-terminated hyperbranched polymer is added to a polyurethane prepolymer, and the reaction is stopped when the hydroxyl content of the system is 0 at 80°C to obtain hyperbranched polyurethane. Post-processing: The hyperbranched polyurethane was cooled to 30°C, and the neutralizing agent triethylamine was added and reacted for 30 minutes. Finally, deionized water was added for high-speed dispersion and emulsification, and acetone was removed under vacuum to obtain high-gloss waterborne polyurethane.

[0036] Example 2 A high-gloss waterborne polyurethane comprises the following raw materials: Isophorone diisocyanate 26g; Polybutylene adipate 32g; Catalyst 0.3g, specifically dibutyltin dilaurate; 5g of hydrophilic chain extender, specifically 1,2-butanediol; 2.6g of lignin was obtained by mixing alkali lignin and acetone at a concentration of 500g / L, stirring at 50℃ for 5h, filtering and separating, evaporating the filtrate to remove the organic solvent, and drying. Konjac gum 2.9g; 16g of hydroxyl-terminated hyperbranched polymer was purchased from Shanghai Huicheng Biotechnology Co., Ltd., brand name Boltorn P500. 80g of deionized water.

[0037] High-gloss waterborne polyurethane is prepared through the following steps: Preparation of polyurethane prepolymer: Polybutylene adipate was placed in a 500mL three-necked flask equipped with a stirrer and heated. After most of the material melted, stirring was started, the temperature was raised and a vacuum was drawn. The prepolymer was dehydrated at 120℃ and a vacuum of 0.08MPa for 2 hours, and then cooled to below 40℃ and stored in a dry container for later use. Polybutylene adipate and isophorone diisocyanate were added to a three-necked flask, along with a catalyst and acetone solvent. The mixture was heated to 80°C and reacted for 2.5 hours. A hydrophilic chain extender was added and the mixture was reacted at 60°C for 1.5 hours. Then lignin and konjac gum were added and reacted for 40 minutes. Finally, acetone solvent was added to adjust the viscosity to obtain a polyurethane prepolymer. Synthesis of hyperbranched polyurethane: A hydroxyl-terminated hyperbranched polymer is added to a polyurethane prepolymer, and the reaction is stopped at 83°C when the hydroxyl content of the system is 0, thus obtaining hyperbranched polyurethane. Post-processing: The hyperbranched polyurethane was cooled to 40°C, and the neutralizing agent triethylamine was added and reacted for 35 minutes. Finally, deionized water was added for high-speed dispersion and emulsification, and acetone was removed under vacuum to obtain high-gloss waterborne polyurethane.

[0038] Example 3 A high-gloss waterborne polyurethane comprises the following raw materials: Isophorone diisocyanate 23g; Polybutylene adipate 29g; 0.2g of catalyst, specifically an organic bismuth catalyst; 4.2g of hydrophilic chain extender, specifically 3g of dimethylolpropionic acid and 1.2g of 1,2-butanediol; 2.1g of lignin was obtained by mixing alkali lignin and tetrahydrofuran at a concentration of 300g / L, stirring at 40℃ for 6h, filtering and separating, evaporating the filtrate to remove the organic solvent, and drying. Konjac gum 2.6g; 13g of hydroxyl-terminated hyperbranched polymer, Wuhan Hyperbranched Resin Technology Co., Ltd., brand name HyPer H10; 74g of deionized water.

[0039] High-gloss waterborne polyurethane is prepared through the following steps: Preparation of polyurethane prepolymer: Polybutylene adipate was placed in a 500mL three-necked flask equipped with a stirrer and heated. After most of the material melted, stirring was started, the temperature was raised and a vacuum was drawn. The prepolymer was dehydrated at 120℃ and a vacuum of 0.08MPa for 2 hours, and then cooled to below 40℃ and stored in a dry container for later use. Polybutylene adipate and isophorone diisocyanate were added to a three-necked flask, along with a catalyst and acetone solvent. The mixture was heated to 80°C and reacted for 2 hours. A hydrophilic chain extender was added and the mixture was reacted at 58°C for 1.5 hours. Then lignin and konjac gum were added and the mixture was reacted for 35 minutes. Finally, acetone solvent was added to adjust the viscosity to obtain a polyurethane prepolymer. Synthesis of hyperbranched polyurethane: A hydroxyl-terminated hyperbranched polymer is added to a polyurethane prepolymer, and the reaction is stopped when the hydroxyl content of the system is 0 at 80°C to obtain hyperbranched polyurethane. Post-processing: The hyperbranched polyurethane was cooled to 35°C, and the neutralizing agent triethylamine was added and reacted for 30 minutes. Finally, deionized water was added for high-speed dispersion and emulsification, and acetone was removed under vacuum to obtain high-gloss waterborne polyurethane.

[0040] Example 4 The only difference between this embodiment and Embodiment 1 is that the lignin in the waterborne polyurethane raw material is different.

[0041] The lignin used in this embodiment is the nitrated modified lignin obtained in Preparation Example 1.

[0042] The preparation method of waterborne polyurethane is the same as that in Example 1.

[0043] Example 5 The only difference between this embodiment and Embodiment 1 is that the lignin in the waterborne polyurethane raw material is different.

[0044] The lignin used in this embodiment is the nitrated modified lignin obtained in Preparation Example 2.

[0045] The preparation method of waterborne polyurethane is the same as that in Example 1.

[0046] Example 6 The only difference between this embodiment and Example 1 is that the terminal hydroxyl hyperbranched polymer in the waterborne polyurethane raw material is different.

[0047] In this embodiment, the hydroxyl-terminated hyperbranched polymer is selected from the partially modified hyperbranched polymer prepared in Preparation Example 3.

[0048] The preparation method of waterborne polyurethane is the same as that in Example 1.

[0049] Example 7 The only difference between this embodiment and Example 1 is that the terminal hydroxyl hyperbranched polymer in the waterborne polyurethane raw material is different.

[0050] In this embodiment, the hydroxyl-terminated hyperbranched polymer is selected from the partially modified hyperbranched polymer prepared in Preparation Example 4.

[0051] The preparation method of waterborne polyurethane is the same as that in Example 1.

[0052] Example 8 The only difference between this embodiment and Embodiment 1 is that the lignin and hydroxyl-terminated hyperbranched polymers in the waterborne polyurethane raw material are different.

[0053] In this embodiment, the lignin used is the nitrated modified lignin obtained in Preparation Example 1, and the hydroxyl-terminated hyperbranched polymer used is the partially modified hyperbranched polymer obtained in Preparation Example 4.

[0054] The preparation method of waterborne polyurethane is the same as that in Example 1.

[0055] Performance testing The high-gloss waterborne polyurethanes prepared in Examples 1-8 and Comparative Examples 1-2 were applied to the surface of leather using a roller coating method. The coatings were then baked in an oven at 100°C for 30 minutes, completely dried, and cooled to form a polyurethane coating. The gloss, adhesion, and other properties of the waterborne polyurethane coatings were tested.

[0056] Gloss: The gloss of the waterborne polyurethane coating was measured using a 60° gloss meter.

[0057] Adhesion: The adhesion is determined according to GB / T 9286-1998 "Test for scratch resistance of paint and varnish films", with a rating of 0-5 as the standard.

[0058] Water resistance: Tested according to GB / T 5209-1985 "Determination of water resistance of paints and varnishes - Immersion method". The substrate is cold-rolled ordinary low carbon steel plate. After immersion for a certain period of time, check whether the water-based polyurethane coating is damaged.

[0059] The test results are shown in Table 1.

[0060] Example 1 86 1 48h non-destructive Example 2 88 0-1 48h non-destructive Example 3 87 1 48h non-destructive Example 4 94 0 48h non-destructive Example 5 95 0 48h non-destructive Example 6 90 0 48h non-destructive Example 7 91 0 48h non-destructive Example 8 98 0 48h non-destructive Comparative Example 1 64 1-2 24-hour non-destructive Comparative Example 2 68 2 30 hours without damage As shown in Table 1, the waterborne polyurethane prepared in this application exhibits a gloss level >85, and the adhesion grade between the polyurethane coating and leather is ≤1. The coating remains undamaged after immersion in water for 48 hours. When applied to leather finishing, the waterborne polyurethane prepared in this application demonstrates high gloss, good water resistance, and excellent adhesion, bonding firmly to the leather. The polyurethane coating has a smooth surface and a high degree of cross-linking, meeting the optical and aesthetic requirements of leather.

[0061] Compared to Example 1, Examples 4-5 involve nitro-modification of the lignin in the waterborne polyurethane raw materials. The original lignin participates in the reaction with -NCO through abundant hydroxyl groups, forming crosslinks with the polyurethane system. The nitrated lignin introduces nitrogen-containing functional groups, which can further enhance the compatibility and crosslinking with the polyurethane system through structures such as hydrogen bonds. The more compact structure improves the water resistance and gloss of the waterborne polyurethane system.

[0062] Compared to Example 1, Examples 6-7 involve partial modification of the hydroxyl-terminated hyperbranched polymer in the waterborne polyurethane raw material. The original hydroxyl-terminated hyperbranched polymer forms a cross-linked interpenetrating network through the reaction of the terminal hydroxyl groups with isocyanate groups. Based on the good leveling and film-forming properties of the hydroxyl-terminated hyperbranched polymer itself, the coating surface is smooth, resulting in high gloss and strong adhesion to leather. Fluorine is introduced into the original hydroxyl-terminated hyperbranched polymer through partial modification. The introduction of fluorine helps to further improve the water resistance and chemical stability of the waterborne polyurethane.

[0063] Compared to Example 1, Comparative Examples 1 and 2 did not include lignin, konjac gum, or hydroxyl-terminated hyperbranched polymer in the raw materials of the waterborne polyurethane, resulting in a decrease in the gloss, adhesion, and water resistance of the polyurethane. This indicates that in the preparation of the waterborne polyurethane of this application, the modification of the polyurethane prepolymer by lignin and konjac gum, and the crosslinking and interpenetration of the hydroxyl-terminated hyperbranched polymer and the polyurethane system, have a synergistic effect in improving the gloss, water resistance, and degree of crosslinking of the waterborne polyurethane.

[0064] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this specific embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A high-gloss waterborne polyurethane, characterized in that, Including the following parts by weight of raw materials: 19-26 parts of isophorone diisocyanate; 24-32 parts of polybutylene adipate; Catalyst 0.1-0.3 parts; 3.5-5 parts of hydrophilic chain extender; Nitrogenated lignin: 1.7-2.6 parts; 2.3-2.9 parts konjac gum; 11-16 parts of hydroxyl-terminated hyperbranched polymer; 65-80 parts deionized water; Nitrogen-modified lignin has a nitrogen content of 5%-8% and includes the following raw materials in parts by weight: 20-24 parts of lignin; 48-53 parts of fuming nitric acid; Acetic anhydride 24-27 parts; The preparation method of lignin is to mix industrial lignin with organic solvent, stir at 30-50℃ for 5-7 hours, filter and separate, take the filtrate, evaporate to remove organic solvent, and dry to obtain lignin. The preparation method of the high-gloss waterborne polyurethane includes the following steps: Preparation of polyurethane prepolymer: Polybutylene adipate was vacuum dehydrated and cooled for later use. Polybutylene adipate and isophorone diisocyanate were added to a three-necked flask, along with a catalyst and acetone solvent. The mixture was heated to 78-80℃ and reacted for 2-2.5 h. A hydrophilic chain extender was added and the mixture was reacted at 55-60℃ for 1-1.5 h. Lignin and konjac gum were then added and reacted for 30-40 min. Acetone was added to adjust the viscosity to obtain the polyurethane prepolymer. Synthesis of hyperbranched polyurethane: Add hydroxyl-terminated hyperbranched polymer to polyurethane prepolymer, heat to 80-83℃ and react until the hydroxyl content of the system is 0 to obtain hyperbranched polyurethane; Post-processing: Cool the hyperbranched polyurethane to 30-40℃, add the neutralizing agent triethylamine and react for 30-35 minutes, finally add deionized water for high-speed dispersion and emulsification, and remove acetone under vacuum to obtain high-gloss waterborne polyurethane.

2. The high-gloss waterborne polyurethane according to claim 1, characterized in that: The hydroxyl-terminated hyperbranched polymer is selected from one or more of Boltorn H2004, Boltorn P500, HyPer H10, and HyPer H40.

3. The high-gloss waterborne polyurethane according to claim 1, characterized in that: The industrial lignin is selected from at least one of alkali lignin and enzymatically hydrolyzed lignin, and the organic solvent is selected from at least one of tetrahydrofuran, acetone, and isopropanol. The mixed concentration of the industrial lignin and the organic solvent is 200-500 g / L.

4. The high-gloss waterborne polyurethane according to claim 2, characterized in that: The hydroxyl-terminated hyperbranched polymer is a partially modified hydroxyl-terminated hyperbranched polymer, comprising the following raw materials in parts by weight: 24-28 parts of hydroxyl-terminated hyperbranched polymer; Perfluorooctanoic acid chloride 13-17 parts.

5. The high-gloss waterborne polyurethane according to claim 1, characterized in that: The catalyst is selected from at least one of dibutyltin dilaurate and an organobismuth catalyst.

6. The high-gloss waterborne polyurethane according to claim 1, characterized in that: The hydrophilic chain extender is selected from at least one of dimethylolbutyric acid, dimethylolpropionic acid, and 1,2-butanediol.

7. The high-gloss waterborne polyurethane according to claim 1, characterized in that, Nitrogenized lignin is prepared by the following method: After mixing lignin and fuming nitric acid, acetic anhydride was added dropwise, and the mixture was stirred in an ice-salt bath for 12-18 hours. The resulting solid precipitate was then repeatedly washed with ice water and subjected to ultracentrifugation to obtain nitrated modified lignin.

8. The high-gloss waterborne polyurethane according to claim 4, characterized in that: When a partially modified hydroxyl-terminated hyperbranched polymer is selected as the end-hydroxyl hyperbranched polymer, the partially modified hydroxyl-terminated hyperbranched polymer is prepared by the following method: A pyridine solution of the hydroxyl-terminated hyperbranched polymer was added to a flask and heated to 25-35°C. Under nitrogen protection, perfluorooctanoic acid chloride was added dropwise with stirring. After the addition was complete, the mixture was heated to 50-70°C and reacted for 3-4 hours. The pyridine and another product, hydrogen chloride, were removed by vacuum. The mixture was then repeatedly washed with toluene and deionized water and dried under vacuum to obtain the partially modified hydroxyl-terminated hyperbranched polymer.