Green bio-based polyurethane adhesive for bamboo winding pipe and preparation method thereof

Abstract

The application discloses a preparation method of a green bio-based polyurethane adhesive for bamboo winding pipes, and specifically comprises the following steps: step 1, fatty aromatic isocyanate, bio-based polyol, a catalyst, a chain extender and acetone are sequentially added into a reaction container, nitrogen is introduced, and then heating and stirring are conducted to obtain a bio-based polyurethane prepolymer; step 2, a bio-based polyurethane emulsion is prepared according to the product obtained in step 1; and step 3, the bio-based polyurethane emulsion obtained in step 2 is blended with a soybean protein solution, a curing agent and nano filler modified by a polyphenol compound, and then uniform stirring is conducted at room temperature to obtain a bio-based polyurethane adhesive for bamboo winding composite pipes. The application further discloses the green bio-based polyurethane adhesive for bamboo winding pipes. The adhesive prepared by the application not only realizes gluing of the bamboo winding pipe, but also reduces consumption of non-renewable resources, and achieves the purpose of environmental protection.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane adhesive technology, and relates to a green bio-based polyurethane adhesive for bamboo-wound pipes. This invention also relates to a method for preparing the green bio-based polyurethane adhesive for bamboo-wound pipes. Background Technology

[0002] In recent years, due to environmental protection requirements, bamboo-wound composite materials have received widespread attention as a key product to replace traditional plastic products. In the production process of bamboo-wound composite pipes, adhesives ensure the overall performance and service life of the pipes by bonding the bamboo layers, enhancing structural strength, improving durability, and optimizing production processes. Currently, the production of bamboo-wound composite pipes mainly relies on petroleum-based adhesives, such as urea-formaldehyde resin, phenolic resin, and polyurethane. However, the use of these adhesives brings environmental pollution and health risks, especially given the finite nature of petroleum resources and the increasing pollution problems generated during their production. To address these challenges, developing environmentally friendly adhesives based on renewable bio-resources has become a necessary direction. Bio-based waterborne polyurethane, with its excellent biocompatibility, low carbon footprint, and biodegradability, has become an important candidate material to replace petroleum-based adhesives. Its overall performance can be improved by controlling its soft and hard segment structure to adapt to different application scenarios. At the same time, bio-based polyurethane can effectively synergistically enhance the adhesion performance of soybean protein adhesives, providing a more environmentally friendly option. Therefore, the use of bio-based polyurethane not only meets the requirements of sustainable development, but also improves the environmental performance of bamboo-wound composite pipes, providing technical support for the application of new bio-based adhesives in this field. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing a green bio-based polyurethane adhesive for bamboo-wound pipes. The adhesive prepared by this method can bond bamboo-wound pipes while reducing the consumption of non-renewable resources, thus achieving the goal of environmental protection.

[0004] Another object of the present invention is to provide a green bio-based polyurethane adhesive for bamboo-wound pipes.

[0005] The first technical solution adopted in this invention is a method for preparing a green bio-based polyurethane adhesive for bamboo-wound pipes, which specifically includes the following steps:

[0006] Step 1: Aliphatic isocyanate, bio-based polyol, catalyst, chain extender and acetone are added to the reaction vessel in sequence, nitrogen gas is introduced and the mixture is heated and stirred to obtain bio-based polyurethane prepolymer.

[0007] Step 2: Prepare a bio-based polyurethane emulsion based on the product obtained in Step 1;

[0008] Step 3: The bio-based polyurethane emulsion obtained in Step 2 is mixed with soybean protein solution, curing agent, and polyphenol compound modified nanofiller. After stirring evenly at room temperature, a bio-based polyurethane adhesive for bamboo-wound composite pipes is obtained.

[0009] The first technical solution of this invention is further characterized by:

[0010] In step 1, the mass of aliphatic isocyanate is 10-18g, the mass of bio-based polyol is 24-35g, the mass of catalyst is 50-100μL, the mass of chain extender is 3-10g, and the volume of acetone is 30mL.

[0011] In step 1, the aliphatic isocyanate is one of hexamethylene diisocyanate, isoflurone diisocyanate, and trimethylhexamethylene diisocyanate;

[0012] The bio-based polyol is at least one of plant oil-based polyol and lignocellulose-based polyol;

[0013] The catalyst is at least one of dibutyltin dilaurate, stannous octoate, stannous oleate, and lead isooctanoate.

[0014] The chain extender is one of dimethylolpropionic acid, dimethylolbutyric acid, dihydroxyhalogenate, sodium ethylenediamine ethanesulfonate, and diethylenetriamine.

[0015] In step 1, the heating temperature is 75-85℃ and the stirring time is 4-6 hours.

[0016] The specific process of step 2 is as follows:

[0017] The temperature of the reaction vessel is lowered to 25-50℃. A salt-forming agent is added to the bio-based polyurethane prepolymer obtained in step 1 and stirred for 0.5-1h to form a salt. Then, 130-180mL of deionized water is added and stirred for 0.5-1.5h to emulsify. Finally, rotary evaporation is carried out at 55℃ to obtain a bio-based waterborne polyurethane emulsion.

[0018] In step 2, the salt-forming agent is one of triethylamine, ammonia, or sodium hydroxide, and the amount of salt-forming agent used is 3-7 mL.

[0019] In step 3, the soybean protein solution is prepared by dissolving soybean protein in 70-85 mL of deionized water and stirring for 1-2 hours, wherein the mass of soybean protein is 15-30 g.

[0020] In step 3, the preparation process of the polyphenol compound-modified nanofiller is as follows:

[0021] The nanofiller was ultrasonically dispersed in deionized water for 15 min to obtain a nanofiller dispersion of 10 mg / mL. Then, the polyphenol compound was dissolved in deionized water to obtain a polyphenol compound aqueous solution of 1 mg / mL. Subsequently, the polyphenol compound aqueous solution was added dropwise to the nanofiller dispersion and stirred at room temperature for 2 h. After centrifugation and drying, the polyphenol compound-modified nanofiller powder was obtained. The volume of the nanofiller dispersion was 8-12 mL, and the volume of the polyphenol compound aqueous solution was 0.5-2 mL.

[0022] In step 3, the mass ratio of bio-based polyurethane emulsion: soybean protein solution: polyphenol-modified nanofiller: curing agent is 1:0.5-1.5:0.01-0.1:0.02-0.15;

[0023] The curing agent is at least one of dicyandiamide, diaminodiphenylmethane, and diaminodiphenyl sulfone.

[0024] Among them, the polyphenolic compound is one of tannic acid, gallic acid, and polydopamine, and the nanofiller is one of lithium diatomaceous earth, zirconium hydrogen phosphate, and layered double hydroxide; thus, polyphenolic compound modified nanofiller is obtained.

[0025] The second technical solution adopted in this invention is a green bio-based polyurethane adhesive for bamboo-wound pipes, which is prepared using the same method as the green bio-based polyurethane adhesive for bamboo-wound pipes.

[0026] The beneficial effects of this invention are as follows:

[0027] (1) This invention selects green and safe aliphatic isocyanates and biopolyols as the main raw materials, uses nanocomposite materials for reinforcement, and combines them with soybean protein to prepare an environmentally friendly polyurethane adhesive. Based on the existing technology, this invention greatly reduces carbon emissions during the production and use of spiral wound pipes.

[0028] (2) This invention increases the application performance of adhesives such as corrosion resistance, antibacterial properties, waterproof properties, and flame retardancy by introducing different nanocomposite fillers, thereby enabling its application in various environments. Detailed Implementation

[0029] The present invention will now be described in detail with reference to specific embodiments.

[0030] The present invention discloses a method for preparing a green bio-based polyurethane adhesive for bamboo-wound pipes, which specifically includes the following steps:

[0031] Step 1: 10-18g of aliphatic isocyanate, 24-35g of bio-based polyol, 50-100μL of catalyst, 3-10g of chain extender and 30mL of acetone are added sequentially to a reaction vessel, nitrogen gas is introduced, and the mixture is heated and stirred at 75-85℃ for 4-6h to obtain bio-based polyurethane prepolymer.

[0032] Among them, the aliphatic isocyanate is one of hexamethylene diisocyanate, isoflurone diisocyanate and trimethylhexamethylene diisocyanate;

[0033] Bio-based polyols are one or more of plant oil-based polyols and lignocellulosic polyols;

[0034] The catalyst is one or more of dibutyltin dilaurate, stannous octoate, stannous oleate, and lead isooctanoate;

[0035] The chain extender is one of dimethylolpropionic acid, dimethylolbutyric acid, dihydroxyhalogenate, sodium ethylenediamine ethanesulfonate, and diethylenetriamine;

[0036] Step 2: Lower the system temperature in the reaction vessel to 25-50℃, then add a salt-forming agent to the bio-based polyurethane prepolymer and stir for 0.5-1 h. Add 130-180 mL of deionized water and stir for 0.5-1.5 h to emulsify. Finally, rotary evaporate at 55℃ to obtain a bio-based aqueous polyurethane emulsion. The salt-forming agent is one of triethylamine, ammonia, or sodium hydroxide. The volume of the salt-forming agent is 3-7 mL.

[0037] Step 3: Add water at room temperature and stir for 1-2 hours to dissolve 15-30g of soy protein in 70-85mL of deionized water to obtain a soy protein solution.

[0038] Step 4: The bio-based polyurethane emulsion, soybean protein solution, polyphenol-modified nanofiller, and curing agent are mixed in a mass ratio of 1:0.5-1.5:0.01-0.1:0.02-0.15 and stirred evenly at room temperature to obtain the bio-based polyurethane adhesive for bamboo-wound composite pipes.

[0039] The preparation process of the polyphenol compound-modified nanofiller is as follows:

[0040] The nanofiller was ultrasonically dispersed in deionized water for 15 min to obtain a nanofiller dispersion of 10 mg / mL. Then, the polyphenol compound was dissolved in deionized water to obtain a polyphenol compound aqueous solution of 1 mg / mL. Subsequently, the polyphenol compound aqueous solution was added dropwise to the nanofiller dispersion and stirred at room temperature for 2 h. After centrifugation and drying, the polyphenol compound-modified nanofiller powder was obtained. The volume of the nanofiller dispersion was 8-12 mL, and the volume of the polyphenol compound aqueous solution was 0.5-2 mL.

[0041] The polyphenol compound is one of tannic acid, gallic acid, and polydopamine;

[0042] The nanofiller is one of lithium diatomaceous earth, zirconium hydrogen phosphate, and layered double hydroxide; a polyphenol compound-modified nanofiller is obtained, specifically including one of lithium diatomaceous earth@tannic acid, zirconium hydrogen phosphate@gallic acid, and layered double hydroxide@polydopamine;

[0043] The curing agent is at least one of dicyandiamide, diaminodiphenylmethane, and diaminodiphenyl sulfone.

[0044] Example 1

[0045] Step 1: 13g of isoflurane diisocyanate, 24g of vegetable oil-based polyol, 3.5g of dimethylolbutyric acid, 50μL of dibutyltin dilaurate, and 30mL of acetone were added to a 250mL three-necked flask. Nitrogen gas was introduced, and the mixture was heated to 75℃ and reacted for 4 hours. The temperature was then lowered to 40℃, and 3mL of triethylamine was added dropwise. The reaction continued for 0.5 hours. Finally, 170mL of deionized water was added and the mixture was stirred for 0.5 hours. The resulting emulsion was then rotary evaporated at 55℃ to remove excess acetone, yielding a bio-based polyurethane emulsion with a solid content of approximately 25%.

[0046] Step 2: Dissolve 25g of soy protein in 75mL of deionized water and stir for 2 hours to obtain a soy protein solution;

[0047] Step 3: Zirconium hydrogen phosphate nanosheets were ultrasonically dispersed in deionized water for 15 min to obtain a 10 mg / mL zirconium hydrogen phosphate dispersion. Then, gallic acid was dissolved in deionized water to obtain a 1 mg / mL gallic acid aqueous solution. Subsequently, the gallic acid aqueous solution was added dropwise to the zirconium hydrogen phosphate dispersion and stirred at room temperature for 2 h to obtain a zirconium hydrogen phosphate@gallic acid dispersion. After centrifugation and drying, zirconium hydrogen phosphate@gallic acid nanofiller was obtained. The volume of the zirconium hydrogen phosphate dispersion was 8 mL, and the volume of the gallic acid aqueous solution was 0.5 mL.

[0048] Step 4: The bio-based polyurethane emulsion, soybean protein solution, zirconium hydrogen phosphate@gallic acid nanofiller, and dicyandiamide are mixed in a mass ratio of 1:0.5:0.01:0.02 and stirred evenly at room temperature to obtain the bio-based polyurethane adhesive for bamboo-wound composite pipes.

[0049] Example 2

[0050] Step 1: 10g hexamethylene diisocyanate, 30g lignocellulose-based polyol, 3g dimethylolbutyric acid, 80μL dibutyltin dilaurate, and 30mL acetone were added to a 250mL three-necked flask. Nitrogen gas was introduced, and the mixture was heated to 80℃ and reacted for 5 hours. The temperature was then lowered to 25℃, and 5mL triethylamine was added dropwise. The reaction continued for 0.8 hours. Finally, 130mL deionized water was added and the mixture was stirred for 1 hour. The resulting emulsion was then rotary evaporated at 55℃ to remove excess acetone, yielding a bio-based polyurethane emulsion with a solid content of approximately 25%.

[0051] Step 2: Dissolve 15g of soy protein in 70mL of deionized water and stir for 1 hour to obtain a soy protein solution;

[0052] Step 3: Disperse lithium diatomaceous earth nanosheets in deionized water by ultrasonication for 15 min to obtain a 10 mg / mL lithium diatomaceous earth dispersion; then, dissolve tannic acid in deionized water to obtain a 1 mg / mL tannic acid aqueous solution, and then add the tannic acid aqueous solution dropwise to the lithium diatomaceous earth dispersion. Stir at room temperature for 2 h to obtain a lithium diatomaceous earth@tannic acid dispersion. After centrifugation and drying, obtain lithium diatomaceous earth@tannic acid nanofiller; the volume of the lithium diatomaceous earth dispersion is 10 mL, and the volume of the tannic acid aqueous solution is 1 mL.

[0053] Step 4: The bio-based polyurethane emulsion, soybean protein solution, lithium diatomaceous earth@tannic acid nanofiller, and dicyandiamide are mixed in a mass ratio of 1:1.2:0.05:0.1 and stirred evenly at room temperature to obtain the bio-based polyurethane adhesive for bamboo-wound composite pipes.

[0054] Example 3

[0055] Step 1: 18g of isoflurane diisocyanate, 35g of vegetable oil-based polyol, 10g of dimethylolbutyric acid, 100μL of stannous octoate, and 30mL of acetone were added to a 250mL three-necked flask. Nitrogen gas was introduced, and the mixture was heated to 85℃ for 6 hours. The temperature was then lowered to 50℃, and 7mL of triethylamine was added dropwise. The reaction continued for 1 hour. Finally, 180mL of deionized water was added and the mixture was stirred for 1.5 hours. The resulting emulsion was then rotary evaporated at 55℃ to remove excess acetone, yielding a bio-based polyurethane emulsion with a solid content of approximately 25%.

[0056] Step 2: Dissolve 30g of soy protein in 85mL of deionized water and stir for 2 hours to obtain a soy protein solution;

[0057] Step 3: The layered double hydroxide nanosheets were ultrasonically dispersed in deionized water for 15 min to obtain a 10 mg / mL layered double hydroxide dispersion. Then, polydopamine was dissolved in deionized water to obtain a 1 mg / mL polydopamine aqueous solution. Subsequently, the polydopamine aqueous solution was added dropwise to the layered double hydroxide dispersion and stirred at room temperature for 2 h to obtain a layered double hydroxide@polydopamine dispersion. After centrifugation and drying, the layered double hydroxide@polydopamine filler was obtained. The volume of the layered double hydroxide dispersion was 12 mL, and the volume of the tannic acid aqueous solution was 2 mL.

[0058] Step 4: The bio-based polyurethane emulsion, soybean protein solution, layered double hydroxide@polydopamine filler, and diaminodiphenylmethane are mixed in a mass ratio of 1:1.5:0.1:0.15 and stirred evenly at room temperature to obtain the bio-based polyurethane adhesive for bamboo-wound composite pipes.

[0059] The green bio-based polyurethane adhesive for bamboo-wound pipes prepared in this invention has a mechanism of action that includes synergistic effects such as hydrogen bonding, physical adsorption, and penetration, enabling it to form a strong bond with bamboo, providing excellent mechanical properties and durability, while also improving the environmental friendliness of the adhesive.

Claims

1. A method for preparing a green bio-based polyurethane adhesive for bamboo-wound pipes, characterized in that: Specifically, the steps include the following: Step 1: Aliphatic isocyanate, bio-based polyol, catalyst, chain extender, and acetone are sequentially added to a reaction vessel. Nitrogen gas is introduced, and the mixture is heated and stirred to obtain a bio-based polyurethane prepolymer. In Step 1, the mass of the aliphatic isocyanate is 10-18 g, the mass of the bio-based polyol is 24-35 g, the mass of the catalyst is 50-100 μL, the mass of the chain extender is 3-10 g, and the volume of acetone is 30 mL. In Step 1, the aliphatic isocyanate is one of hexamethylene diisocyanate, isoflurane diisocyanate, and trimethylhexamethylene diisocyanate. The bio-based polyol is at least one of plant oil-based polyol and lignocellulose-based polyol; The catalyst is at least one of dibutyltin dilaurate, stannous octoate, stannous oleate, and lead isooctanoate. The chain extender is one of dimethylolpropionic acid, dimethylolbutyric acid, dihydroxyhalogenate, sodium ethylenediamine ethanesulfonate, and diethylenetriamine; In step 1, the heating temperature is 75-85℃ and the stirring time is 4-6 h; Step 2: Prepare a bio-based polyurethane emulsion based on the product obtained in Step 1. The specific process of Step 2 is as follows: lower the temperature of the reaction vessel to 25-50℃, add a salt-forming agent to the bio-based polyurethane prepolymer obtained in Step 1 and stir for 0.5-1 h to form a salt. Then, add 130-180 mL of deionized water and stir for 0.5-1.5 h to emulsify. Finally, perform rotary evaporation at 55℃ to obtain a bio-based aqueous polyurethane emulsion. In Step 2, the salt-forming agent is one of triethylamine, ammonia, or sodium hydroxide, and the amount of the salt-forming agent used is 3-7 mL. Step 3: The bio-based polyurethane emulsion obtained in Step 2 is mixed with soybean protein solution, curing agent, and polyphenol compound modified nanofiller. After stirring evenly at room temperature, a bio-based polyurethane adhesive for bamboo-wound composite pipes is obtained. In Step 3, the soybean protein solution is prepared by dissolving soybean protein in 70-85 mL of deionized water and stirring for 1-2 hours. The mass of soybean protein is 15-30 g. In step 3, the preparation process of the polyphenol compound-modified nanofiller is as follows: The nanofiller was ultrasonically dispersed in deionized water for 15 min to obtain a 10 mg / mL nanofiller dispersion. Then, the polyphenol compound was dissolved in deionized water to obtain a 1 mg / mL polyphenol compound aqueous solution. Subsequently, the polyphenol compound aqueous solution was added dropwise to the nanofiller dispersion and stirred at room temperature for 2 h. After centrifugation and drying, the polyphenol compound-modified nanofiller powder was obtained. The volume of the nanofiller dispersion was 8-12 mL, and the volume of the polyphenol compound aqueous solution was 0.5-2 mL. In step 3, the mass ratio of bio-based polyurethane emulsion: soybean protein solution: polyphenol-modified nanofiller: curing agent is 1:0.5-1.5:0.01-0.1:0.02-0.15; The curing agent is at least one of dicyandiamide, diaminodiphenylmethane, and diaminodiphenyl sulfone. Among them, the polyphenolic compound is one of tannic acid, gallic acid, and polydopamine, and the nanofiller is one of lithium diatomaceous earth, zirconium hydrogen phosphate, and layered double hydroxide; thus, polyphenolic compound modified nanofiller is obtained.

2. A green bio-based polyurethane adhesive for bamboo-wound pipes, prepared by the method described in claim 1.