Solvent-free castor oil-based polyurethane adhesive and preparation method thereof

Abstract

The invention discloses a solvent-free castor oil-based polyurethane adhesive and a preparation method thereof, and belongs to the technical field of bio-based polyurethane adhesives. The polyurethane adhesive comprises a component A and a component B. The component A is prepared from the following raw materials in parts by mass: 5 to 15 parts of triethanolamine modified castor oil polyol, 5 to 15 parts of silane modified castor oil, 10 to 20 parts of polyester polyol, 5 to 15 parts of polyether polyol, 2 to 4 parts of isosorbide, 15 to 25 parts of filler and 0.1 to 0.2 part of catalyst; the component B is prepared from the following raw materials in parts by mass: 40 to 60 parts of aliphatic isocyanate, 5 to 10 parts of isocyanate siloxane, 10 to 20 parts of polyester polyol and 1 to 6 parts of chain extender. According to the polyurethane adhesive system disclosed by the invention, no organic solvent is used, the bio-based polyhydric alcohol is used as the raw material to replace part of petroleum-based polyhydric alcohol, and the polyurethane adhesive has good environment-friendly sustainability, high strength and high heat resistance.

Description

Technical Field

[0001] This invention belongs to the field of bio-based polyurethane adhesive technology, specifically relating to a solvent-free castor oil-based polyurethane adhesive and its preparation method. Background Technology

[0002] Polyurethane adhesives occupy an important position in daily life and industry due to their excellent bonding properties and wide range of applications. They can achieve excellent chemical adhesion to various substrates, including porous materials such as foam, plastics, wood, leather, fabrics, paper, and ceramics, as well as smooth surfaces such as metals, glass, and rubber.

[0003] The main components of polyurethane adhesives include isocyanates and polyols. The core reaction mechanism involves the chemical reaction between isocyanate groups and substances containing active hydrogen to generate polyurethane groups. This reaction endows polyurethane adhesives with high strength and flexibility.

[0004] Most polyurethane raw materials are petrochemicals. With the increasing scarcity of petroleum resources and the growing global trend towards environmental protection and energy conservation, the replacement of petroleum-based raw materials with renewable bio-based raw materials has received widespread attention in the field of environmentally friendly polyurethane materials.

[0005] Currently, castor oil is an important raw material for the production of bio-based polyurethane adhesives. Castor oil is renewable and biodegradable, and its long carbon chain structure allows the adhesive layer to remain flexible at -20°C, solving the problem of low-temperature brittleness in traditional polyurethane adhesives. However, castor oil has a low hydroxyl value and poor reactivity, resulting in low crosslinking density and poor heat resistance in polyurethane adhesives, which severely restricts its widespread application. Summary of the Invention

[0006] The purpose of this invention is to provide a solvent-free castor oil-based polyurethane adhesive and its preparation method, which can solve the problem of poor heat resistance of existing castor oil-based polyurethane adhesives.

[0007] The objective of this invention can be achieved through the following technical solutions: A solvent-free castor oil-based polyurethane adhesive, the adhesive comprising component A and component B; Component A, by mass parts, includes the following raw materials: 5-15 parts of triethanolamine-modified castor oil polyol, 5-15 parts of silane-modified castor oil, 10-20 parts of polyester polyol, 5-15 parts of polyether polyol, 2-4 parts of isosorbide, 15-25 parts of filler, and 0.1-0.2 parts of catalyst. Component B, by mass parts, includes the following raw materials: 40-60 parts aliphatic isocyanate, 5-10 parts isocyanate-based siloxane, 10-20 parts polyester polyol, and 1-6 parts chain extender.

[0008] This invention replaces a portion of the petroleum-based polyester polyol / polyether polyol with biomass-modified castor oil in component A of the adhesive, and simultaneously adds isosorbide to increase the proportion of bio-based materials and reduce dependence on petroleum resources. The triethanolamine-modified castor oil polyol has a higher hydroxyl functionality on its molecular chain, resulting in a denser cross-linked network structure compared to the polyurethane network formed by the reaction of castor oil and isocyanate, thus improving heat resistance. Furthermore, the introduction of tertiary amine groups promotes the hydrolytic cross-linking of siloxane groups. The introduction of siloxane groups into the silane-modified castor oil molecular chain allows for the formation of an interpenetrating cross-linked network with polyurethane, utilizing the hydrolytic cross-linking properties of siloxane groups with moisture in the air. This enhances the cross-linking effect of the adhesive, hinders moisture penetration, and improves the hydrophobicity of the cured adhesive. Additionally, the siloxane groups have a strong affinity for inorganic substrates and fillers, improving the adhesion of the adhesive. Adding isosorbide to a high molecular weight polyol system, isosorbide being a bio-based material with a diol structure, introduces a rigid alicyclic structure into polyurethane adhesives. This synergistic effect with the flexible long chains of castor oil maintains the adhesive's flexibility while giving it better strength and heat resistance.

[0009] The adhesive of this invention uses aliphatic isocyanate as the main component of component B, which can react with polyol in component A to form a structurally stable polyurethane. The isocyanate-based siloxane contains both isocyanate groups and siloxane groups, which can promote the compatibility of silane-modified castor oil in component A with component B. It can not only react with polyols, but also achieve co-crosslinking through siloxane groups, condense with hydroxyl groups on the substrate surface, form chemical bonds, and enhance the adhesive strength.

[0010] Furthermore, the preparation steps of the triethanolamine-modified castor oil polyol are as follows: S1. Weigh castor oil, triethanolamine and catalyst and stir to mix; S2. Heat to 150℃ and stir for 2-3 hours to obtain triethanolamine-modified castor oil polyol.

[0011] Furthermore, the molar ratio of castor oil to triethanolamine is 1:2-3.

[0012] Furthermore, the catalyst is one of lead oxide and lithium hydroxide; The catalyst is 0.2-0.3% of the total mass of castor oil and triethanolamine.

[0013] In the preparation of triethanolamine-modified castor oil polyol, castor oil undergoes an ester exchange reaction with triethanolamine. The reaction is promoted by the molar excess of triethanolamine to generate triethanolamine-modified castor oil polyol.

[0014] Furthermore, the preparation steps of the silane-modified castor oil are as follows: Step 1: Weigh castor oil and 3-mercaptopropyltrimethoxysilane and stir to mix. Add photoinitiator UV1173 and acetone to the mixture and stir to obtain the reactant. Step 2: Under room temperature ultraviolet light irradiation, the reactants are stirred and reacted for 6-8 hours. Acetone is removed by rotary evaporation to obtain silane-modified castor oil.

[0015] Furthermore, the molar ratio of castor oil to 3-mercaptopropyltrimethoxysilane is 1:2.4-3.2.

[0016] Furthermore, the photoinitiator UV1173 is 0.8-0.9% of the castor oil mass.

[0017] Furthermore, the acetone is 1.5-2 times the total mass of castor oil and 3-mercaptopropyltrimethoxysilane.

[0018] In the preparation of silane-modified castor oil, the unsaturated double bonds on castor oil undergo an addition reaction with the mercapto groups of 3-mercaptopropyltrimethoxysilane, introducing methoxysilane into the castor oil molecular chain. Under mild reaction conditions, the resulting silane-modified castor oil contains long hydrophobic carbon chains, active hydroxyl groups, and hydrolyzable methoxysilane groups. This allows the siloxane crosslinking network in the adhesive to form an interpenetrating structure with the polyurethane network, improving the dispersion uniformity of inorganic fillers in the system.

[0019] Furthermore, the polyester polyol is at least one of oxalic acid polyester polyol and adipic acid polyester polyol; The polyether polyol is at least one of polypropylene glycol, polypropylene triol, and polytetrahydrofuran ether glycol.

[0020] Furthermore, the filler is at least one selected from calcium carbonate, silica powder, talc, and alumina.

[0021] Furthermore, the catalyst is at least one selected from stannous octoate, dibutyltin dilaurate, and zinc isooctanoate.

[0022] Furthermore, the aliphatic isocyanate is at least one selected from hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and isophorone diisocyanate.

[0023] Furthermore, the isocyanate-based siloxane is at least one of propyltriethoxysilane and 3-isocyanate-based propyltrimethoxysilane.

[0024] Further, the chain extender is at least one selected from 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, and trimethylolpropane.

[0025] This invention also provides a method for preparing a solvent-free castor oil-based polyurethane adhesive, which includes the following steps: Step 1: Prepare component A raw materials according to the proportion. Mix triethanolamine modified castor oil polyol, silane modified castor oil, polyester polyol, polyether polyol, isosorbide, filler and catalyst, stir at 60-80℃ for 2-3 hours, and degas under vacuum to obtain component A. Step 2: Prepare the raw materials for component B according to the proportion. Mix aliphatic isocyanate, isocyanate-based siloxane, polyester polyol and chain extender, stir and react at 80-100℃ for 3-5 hours, and then degas under vacuum to obtain component B.

[0026] The beneficial effects of this invention are: (1) The polyurethane adhesive system of the present invention does not use organic solvents, and the raw materials use castor oil or isosorbide, which are bio-based polyols, to replace part of the petroleum-based polyols, which can reduce the dependence on petroleum resources. The polyurethane adhesive has good environmental sustainability.

[0027] (2) The castor oil polyol in the polyurethane adhesive provided by the present invention includes triethanolamine-modified castor oil polyol and silane-modified castor oil. Triethanolamine-modified castor oil polyol increases the hydroxyl value of the castor oil molecular chain by transesterification reaction. Silane-modified castor oil grafts highly reactive siloxanes onto the castor oil molecular chain by double bond and mercapto group reaction. Both participate in the polyurethane formation reaction. It can improve the reactivity through high hydroxyl value and siloxane group, and can also promote the hydrolysis and crosslinking of siloxanes by triethanolamine-modified castor oil polyol. This makes the siloxane crosslinking network in the polyurethane adhesive form an interpenetrating structure with the polyurethane network, improve the strength and heat resistance, and enhance the adhesion to the substrate.

[0028] (3) In this invention, isosorbide is added to component A of the adhesive. The rigid structure of isosorbide is interspersed in long-chain castor oil-based polyurethane to balance the strength and toughness of the adhesive.

[0029] (4) The polyurethane adhesive component B of the present invention uses aliphatic isocyanate. The cured adhesive layer is not prone to yellowing under long-term ultraviolet irradiation and is resistant to aging. Isocyanate-based siloxane is added at the same time. Isocyanate-based siloxane contains both isocyanate groups and siloxane groups, which can promote the compatibility of silane-modified castor oil in component A with component B. It can not only react with polyols, but also achieve co-crosslinking through siloxane groups, condense with hydroxyl groups on the surface of the substrate, form chemical bonds, and enhance the adhesive strength of the adhesive. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] Preparation Example

[0032] Preparation Example 1

[0033] Preparation of triethanolamine-modified castor oil polyols: S1. Weigh castor oil and triethanolamine in a molar ratio of 1:2.5 and add them to a three-necked flask. Then weigh lithium hydroxide at 0.2% of the total mass of castor oil and triethanolamine and add it to the three-necked flask. Stir and mix.

[0034] S2. Start stirring, heat the three-necked flask to 150°C, and continue stirring for 2.5 hours to obtain triethanolamine-modified castor oil polyol.

[0035] Preparation Example 2

[0036] Preparation of silane-modified castor oil: Step 1: Weigh castor oil and 3-mercaptopropyltrimethoxysilane at a molar ratio of 1:3.0 and add them to a flask. Start stirring and mix thoroughly. Then add photoinitiator UV1173 and acetone to the mixture. The photoinitiator UV1173 is 0.85% of the mass of castor oil, and the acetone is 1.6 times the total mass of castor oil and 3-mercaptopropyltrimethoxysilane. Stir and mix thoroughly to obtain the reactants.

[0037] Step 2: The reactants were placed at room temperature and irradiated with ultraviolet light (1700W, 365nm). The mixture was stirred for 7 hours, and acetone was removed by rotary evaporation to obtain pale yellow silane-modified castor oil.

[0038] Preparation Example 3

[0039] Preparation of silane-modified castor oil: Step 1: Weigh castor oil and 3-mercaptopropyltrimethoxysilane at a molar ratio of 1:2.4 and add them to a flask. Start stirring and mix thoroughly. Then add photoinitiator UV1173 and acetone to the mixture. The photoinitiator UV1173 is 0.85% of the mass of castor oil, and the acetone is 1.6 times the total mass of castor oil and 3-mercaptopropyltrimethoxysilane. Stir and mix thoroughly to obtain the reactants.

[0040] Step 2: The reactants were placed at room temperature and irradiated with ultraviolet light (1700W, 365nm). The mixture was stirred for 7 hours, and acetone was removed by rotary evaporation to obtain pale yellow silane-modified castor oil.

[0041] Preparation Example 4

[0042] Preparation of silane-modified castor oil: Step 1: Weigh castor oil and 3-mercaptopropyltrimethoxysilane at a molar ratio of 1:3.2 and add them to a flask. Start stirring and mix thoroughly. Then add photoinitiator UV1173 and acetone to the mixture. The photoinitiator UV1173 is 0.85% of the mass of castor oil, and the acetone is 1.6 times the total mass of castor oil and 3-mercaptopropyltrimethoxysilane. Stir and mix thoroughly to obtain the reactants.

[0043] Step 2: The reactants were placed at room temperature and irradiated with ultraviolet light (1700W, 365nm). The mixture was stirred for 7 hours, and acetone was removed by rotary evaporation to obtain pale yellow silane-modified castor oil.

[0044] Example

[0045] Example 1

[0046] A solvent-free castor oil-based polyurethane adhesive, comprising component A and component B, wherein component A comprises the following raw materials by mass parts: Preparation Example 1: 10 parts of triethanolamine-modified castor oil polyol; Preparation Example 2: 10 parts of silane-modified castor oil; 15 parts of adipic acid polyester polyol; 10 parts of polyoxypropylene glycol; 3 parts of isosorbide; 20 parts of calcium carbonate; and 0.1 parts of dibutyltin dilaurate catalyst.

[0047] Component B, by mass parts, includes the following raw materials: 50 parts of isophorone diisocyanate, 8 parts of 3-isocyanatopropyltrimethoxysilane, 15 parts of adipic acid polyester polyol, and 3 parts of 1,4-butanediol.

[0048] The specific preparation steps of the adhesive are as follows: Step 1: Prepare component A raw materials according to the proportion. Mix triethanolamine modified castor oil polyol, silane modified castor oil, adipic acid polyester polyol, polyoxypropylene glycol, isosorbide, calcium carbonate and dibutyltin dilaurate catalyst, stir at 70°C for 3 hours, and degas under vacuum to obtain component A.

[0049] Step 2: Prepare the raw materials for component B according to the proportion. Mix isophorone diisocyanate, 3-isocyanate-propyltrimethoxysilane, adipic acid polyester polyol and 1,4-butanediol, stir and react at 90°C for 4 hours, and then degas under vacuum to obtain component B.

[0050] Example 2

[0051] The only difference from Example 1 is that the silane-modified castor oil prepared in Example 3 is used in place of the silane-modified castor oil prepared in Example 2 by the same mass, while the other conditions and steps are the same as in Example 1.

[0052] Example 3

[0053] The only difference from Example 1 is that the silane-modified castor oil prepared in Example 4 is used in place of the silane-modified castor oil prepared in Example 2 by the same mass, while the other conditions and steps are the same as in Example 1.

[0054] Example 4

[0055] The only difference from Example 1 is that the mass fraction of modified castor oil in component A of the solventless castor oil-based polyurethane adhesive is adjusted. The mass fraction of triethanolamine-modified castor oil polyol prepared in Example 1 is increased to 15 parts, and the mass fraction of silane-modified castor oil prepared in Example 2 is reduced to 5 parts. Other conditions and steps are the same as in Example 1.

[0056] Example 5

[0057] The only difference from Example 1 is that the mass fraction of modified castor oil in component A of the solventless castor oil-based polyurethane adhesive is adjusted. The mass fraction of triethanolamine-modified castor oil polyol prepared in Example 1 is reduced to 5 parts, and the mass fraction of silane-modified castor oil prepared in Example 2 is increased to 15 parts. Other conditions and steps are the same as in Example 1.

[0058] Example 6

[0059] The only difference from Example 1 is that the mass fraction of isosorbide in component A of the solvent-free castor oil-based polyurethane adhesive is adjusted to 2 parts, while the other conditions and steps are the same as in Example 1.

[0060] Example 7

[0061] The only difference from Example 1 is that the mass fraction of isosorbide in component A of the solvent-free castor oil-based polyurethane adhesive is adjusted to 4 parts, while the other conditions and steps are the same as in Example 1.

[0062] Example 8

[0063] The only difference from Example 1 is that the mass fraction of 3-isocyanate-propyltrimethoxysilane in component B of the solvent-free castor oil-based polyurethane adhesive is adjusted, and the mass fraction of 3-isocyanate-propyltrimethoxysilane is reduced to 5 parts.

[0064] Example 9

[0065] The only difference from Example 1 is that the mass fraction of 3-isocyanate-propyltrimethoxysilane in component B of the solventless castor oil-based polyurethane adhesive is adjusted, and the mass fraction of 3-isocyanate-propyltrimethoxysilane is increased to 10 parts.

[0066] Comparative Example 1

[0067] The only difference from Example 1 is that the triethanolamine-modified castor oil polyol is replaced by an equal amount of glycerol-modified castor oil polyol.

[0068] The preparation steps of glycerol-modified castor oil polyol are as follows: A1. Weigh castor oil and glycerin at a molar ratio of 1:2.5 and add them to a three-necked flask. Then weigh out 0.2% of the total mass of castor oil and glycerin, add it to the three-necked flask, and stir to mix.

[0069] A2. Start stirring, heat the three-necked flask to 150°C, and continue stirring for 2.5 hours to obtain glycerol-modified castor oil polyol.

[0070] A solvent-free castor oil-based polyurethane adhesive, comprising component A and component B, wherein component A comprises the following raw materials by mass parts: The comparative example prepared 10 parts of glycerol-modified castor oil polyol, 10 parts of silane-modified castor oil prepared in Preparation Example 2, 15 parts of adipic acid polyester polyol, 10 parts of polyoxypropylene glycol, 3 parts of isosorbide, 20 parts of calcium carbonate, and 0.1 parts of dibutyltin dilaurate catalyst.

[0071] Component B, by mass parts, includes the following raw materials: 50 parts of isophorone diisocyanate, 8 parts of 3-isocyanatopropyltrimethoxysilane, 15 parts of adipic acid polyester polyol, and 3 parts of 1,4-butanediol.

[0072] The specific preparation steps of the adhesive are as follows: Step 1: Prepare component A raw materials according to the proportions. Mix glycerol-modified castor oil polyol, silane-modified castor oil, adipic acid polyester polyol, polyoxypropylene glycol, isosorbide, calcium carbonate and dibutyltin dilaurate catalyst, stir at 70°C for 3 hours, and degas under vacuum to obtain component A.

[0073] Step 2: Prepare the raw materials for component B according to the proportion. Mix isophorone diisocyanate, 3-isocyanate-propyltrimethoxysilane, adipic acid polyester polyol and 1,4-butanediol, stir and react at 90°C for 4 hours, and then degas under vacuum to obtain component B.

[0074] Comparative Example 2

[0075] The only difference from Example 1 is that castor oil is used instead of silane-modified castor oil.

[0076] A solvent-free castor oil-based polyurethane adhesive, comprising component A and component B, wherein component A comprises the following raw materials by mass parts: Preparation Example 1 prepared 10 parts of triethanolamine-modified castor oil polyol, 10 parts of castor oil, 15 parts of adipic acid polyester polyol, 10 parts of polyoxypropylene glycol, 3 parts of isosorbide, 20 parts of calcium carbonate, and 0.1 parts of dibutyltin dilaurate catalyst.

[0077] Component B, by mass parts, includes the following raw materials: 50 parts of isophorone diisocyanate, 8 parts of 3-isocyanatopropyltrimethoxysilane, 15 parts of adipic acid polyester polyol, and 3 parts of 1,4-butanediol.

[0078] The specific preparation steps of the adhesive are as follows: Step 1: Prepare component A raw materials according to the proportion. Mix triethanolamine-modified castor oil polyol, castor oil, adipic acid polyester polyol, polyoxypropylene glycol, isosorbide, calcium carbonate and dibutyltin dilaurate catalyst, stir at 70°C for 3 hours, and degas under vacuum to obtain component A.

[0079] Step 2: Prepare the raw materials for component B according to the proportion. Mix isophorone diisocyanate, 3-isocyanate-propyltrimethoxysilane, adipic acid polyester polyol and 1,4-butanediol, stir and react at 90°C for 4 hours, and then degas under vacuum to obtain component B.

[0080] Comparative Example 3

[0081] The only difference from Example 1 is that castor oil is used instead of triethanolamine to modify castor oil polyol.

[0082] A solvent-free castor oil-based polyurethane adhesive, comprising component A and component B, wherein component A comprises the following raw materials by mass parts: 10 parts castor oil, 10 parts silane-modified castor oil prepared in Preparation Example 2, 15 parts adipic acid polyester polyol, 10 parts polyoxypropylene glycol, 3 parts isosorbide, 20 parts calcium carbonate, and 0.1 parts dibutyltin dilaurate catalyst.

[0083] Component B, by mass parts, includes the following raw materials: 50 parts of isophorone diisocyanate, 8 parts of 3-isocyanatopropyltrimethoxysilane, 15 parts of adipic acid polyester polyol, and 3 parts of 1,4-butanediol.

[0084] The specific preparation steps of the adhesive are as follows: Step 1: Prepare component A raw materials according to the proportion. Mix castor oil, silane-modified castor oil, adipic acid polyester polyol, polyoxypropylene glycol, isosorbide, calcium carbonate and dibutyltin dilaurate catalyst, stir at 70°C for 3 hours, and degas under vacuum to obtain component A.

[0085] Step 2: Prepare the raw materials for component B according to the proportion. Mix isophorone diisocyanate, 3-isocyanate-propyltrimethoxysilane, adipic acid polyester polyol and 1,4-butanediol, stir and react at 90°C for 4 hours, and then degas under vacuum to obtain component B.

[0086] Comparative Example 4

[0087] The only difference from Example 1 is that isosorbide is not added to component A of the solvent-free castor oil-based polyurethane adhesive.

[0088] A solvent-free castor oil-based polyurethane adhesive, comprising component A and component B, wherein component A comprises the following raw materials by mass parts: Preparation Example 1: 10 parts of triethanolamine-modified castor oil polyol; Preparation Example 2: 10 parts of silane-modified castor oil; 15 parts of adipic acid polyester polyol; 10 parts of polyoxypropylene glycol; 20 parts of calcium carbonate; and 0.1 parts of dibutyltin dilaurate catalyst.

[0089] Component B, by mass parts, includes the following raw materials: 50 parts of isophorone diisocyanate, 8 parts of 3-isocyanatopropyltrimethoxysilane, 15 parts of adipic acid polyester polyol, and 3 parts of 1,4-butanediol.

[0090] The specific preparation steps of the adhesive are as follows: Step 1: Prepare component A raw materials according to the proportion. Mix triethanolamine modified castor oil polyol, silane modified castor oil, adipic acid polyester polyol, polypropylene glycol, calcium carbonate and dibutyltin dilaurate catalyst, stir at 70°C for 3 hours, and degas under vacuum to obtain component A.

[0091] Step 2: Prepare the raw materials for component B according to the proportion. Mix isophorone diisocyanate, 3-isocyanate-propyltrimethoxysilane, adipic acid polyester polyol and 1,4-butanediol, stir and react at 90°C for 4 hours, and then degas under vacuum to obtain component B.

[0092] Comparative Example 5

[0093] The only difference from Example 1 is that 3-isocyanate-propyltrimethoxysilane is not added to component B of the solvent-free castor oil-based polyurethane adhesive.

[0094] A solvent-free castor oil-based polyurethane adhesive, comprising component A and component B, wherein component A comprises the following raw materials by mass parts: Preparation Example 1: 10 parts of triethanolamine-modified castor oil polyol; Preparation Example 2: 10 parts of silane-modified castor oil; 15 parts of adipic acid polyester polyol; 10 parts of polyoxypropylene glycol; 3 parts of isosorbide; 20 parts of calcium carbonate; and 0.1 parts of dibutyltin dilaurate catalyst.

[0095] Component B, by mass parts, includes the following raw materials: 50 parts of isophorone diisocyanate, 15 parts of adipic acid polyester polyol, and 3 parts of 1,4-butanediol.

[0096] The specific preparation steps of the adhesive are as follows: Step 1: Prepare component A raw materials according to the proportion. Mix triethanolamine modified castor oil polyol, silane modified castor oil, adipic acid polyester polyol, polyoxypropylene glycol, isosorbide, calcium carbonate and dibutyltin dilaurate catalyst, stir at 70°C for 3 hours, and degas under vacuum to obtain component A.

[0097] Step 2: Prepare the raw materials for component B according to the proportion. Mix isophorone diisocyanate, adipic acid polyester polyol and 1,4-butanediol, stir and react at 90°C for 4 hours, and then degas under vacuum to obtain component B.

[0098] The performance of the polyurethane adhesives prepared in Examples 1-9 and Comparative Examples 1-5 was tested, and the results are shown in Table 1.

[0099] The polyurethane adhesives prepared in the examples and comparative examples are used after the components A and B are mixed evenly at a mass ratio of 2:1.

[0100] Tensile strength and elongation at break testing: The adhesive mixed according to the above ratio was coated on a polytetrafluoroethylene plate, placed at room temperature for 12 hours, and then transferred to an oven to cure at 50°C for 24 hours. The cured adhesive layer was cut with a cutter to obtain dumbbell-shaped samples, and its tensile strength and elongation at break were tested on a universal testing machine at a tensile rate of 100 mm / min.

[0101] Peel strength test: The adhesive mixed in the above proportions was applied to an aluminum foil with a size of 12cm×15cm. The two aluminum foils were then laminated by roller pressing and cured at 60℃ for 72h. The adhesive layer thickness was 10μm. The test was conducted in accordance with GB / T2790-1995 "Test method for peel strength of adhesives at 180°, flexible materials versus rigid materials". The bonded sample was cut into a strip shape of 15mm×200mm. The unbonded ends of the two sides of the adhesive layer were symmetrically clamped on the upper and lower clamps of the universal testing machine. The testing machine was started and the separation rate of the upper and lower clamps was set to 100mm / min. The peel strength was then measured.

[0102] Thermal aging performance test: The above-bonded sample was placed in an oven at 180℃ for 24 hours and the peel strength was tested after aging.

[0103] Table 1

[0104] As can be seen from Table 1, in the polyurethane adhesive prepared in the embodiments of the present invention, triethanolamine-modified castor oil polyol, silane-modified castor oil, isosorbide, and isocyanate-based siloxane have a synergistic effect, which helps to generate a highly cross-linked network structure after the adhesive is cured, thereby improving the strength and heat resistance of polyurethane. Compared with the comparative example, the polyurethane adhesive of Example 1 has higher tensile strength and glass strength, better thermal stability, and can maintain a certain toughness.

[0105] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0106] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A solvent-free castor oil-based polyurethane adhesive, characterized in that, The adhesive comprises component A and component B; Component A, by mass parts, includes the following raw materials: 5-15 parts of triethanolamine-modified castor oil polyol, 5-15 parts of silane-modified castor oil, 10-20 parts of polyester polyol, 5-15 parts of polyether polyol, 2-4 parts of isosorbide, 15-25 parts of filler, and 0.1-0.2 parts of catalyst. Component B, by mass parts, includes the following raw materials: 40-60 parts aliphatic isocyanate, 5-10 parts isocyanate-based siloxane, 10-20 parts polyester polyol, and 1-6 parts chain extender.

2. The solvent-free castor oil-based polyurethane adhesive according to claim 1, characterized in that, The preparation steps of the triethanolamine-modified castor oil polyol are as follows: S1. Weigh castor oil, triethanolamine and catalyst and stir to mix; S2. Heat to 150℃ and stir for 2-3 hours to obtain triethanolamine-modified castor oil polyol.

3. The solvent-free castor oil-based polyurethane adhesive according to claim 2, characterized in that, The molar ratio of castor oil to triethanolamine is 1:2-3.

4. The solvent-free castor oil-based polyurethane adhesive according to claim 2, characterized in that, The catalyst is one of lead oxide and lithium hydroxide; The catalyst is 0.2-0.3% of the total mass of castor oil and triethanolamine.

5. The solvent-free castor oil-based polyurethane adhesive according to claim 1, characterized in that, The preparation steps of the silane-modified castor oil are as follows: Step 1: Weigh castor oil and 3-mercaptopropyltrimethoxysilane and stir to mix. Add photoinitiator UV1173 and acetone to the mixture and stir to obtain the reactant. Step 2: Under room temperature ultraviolet light irradiation, the reactants are stirred and reacted for 6-8 hours. Acetone is removed by rotary evaporation to obtain silane-modified castor oil.

6. The solvent-free castor oil-based polyurethane adhesive according to claim 5, characterized in that, The molar ratio of castor oil to 3-mercaptopropyltrimethoxysilane is 1:2.4-3.

2.

7. The solvent-free castor oil-based polyurethane adhesive according to claim 5, characterized in that, The photoinitiator UV1173 is 0.8-0.9% of the castor oil by weight; The acetone is 1.5-2 times the total mass of castor oil and 3-mercaptopropyltrimethoxysilane.

8. The solvent-free castor oil-based polyurethane adhesive according to claim 1, characterized in that, The polyester polyol is at least one of oxalic acid polyester polyol and adipic acid polyester polyol; The polyether polyol is at least one of polypropylene glycol, polypropylene triol, and polytetrahydrofuran ether glycol.

9. The solvent-free castor oil-based polyurethane adhesive according to claim 1, characterized in that, The isocyanate-based siloxane is at least one of propyltriethoxysilane and 3-isocyanate-based propyltrimethoxysilane.

10. A method for preparing a solvent-free castor oil-based polyurethane adhesive, characterized in that, The preparation of the solvent-free castor oil-based polyurethane adhesive as described in any one of claims 1-9 comprises the following steps: Step 1: Prepare component A raw materials according to the proportion. Mix triethanolamine modified castor oil polyol, silane modified castor oil, polyester polyol, polyether polyol, isosorbide, filler and catalyst, stir at 60-80℃ for 2-3 hours, and degas under vacuum to obtain component A. Step 2: Prepare the raw materials for component B according to the proportion. Mix aliphatic isocyanate, isocyanate-based siloxane, polyester polyol and chain extender, stir and react at 80-100℃ for 3-5 hours, and then degas under vacuum to obtain component B.

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