A post-crosslinking system waterborne polyurethane and its application

Abstract

The present invention provides a post-crosslinked waterborne polyurethane system and its applications. The prepared waterborne polyurethane-polyurea contains borate precursor building blocks with polycyclic intramolecular N→B coordination bonds at the molecular chain ends. As the moisture content decreases during film formation and drying, post-crosslinking occurs between the molecular chains, resulting in excellent strength, heat resistance, and water resistance. Furthermore, the aqueous dispersion exhibits low viscosity and is suitable for applications in shoe adhesives, automotive interior adhesives, electronic adhesives, and other fields.

Description

Technical Field

[0001] The invention relates to a post-crosslinking system waterborne polyurethane and application thereof, belonging to the field of waterborne polyurethane resins. Background Art

[0002] Polyurethane or polyurethane-urea aqueous dispersions use only water as a dispersion medium, which is in line with current international development trends and national policy guidelines. While they can provide performance comparable to oil-based systems, they are also environmentally friendly and environmentally friendly during use. Therefore, they are widely used in coatings, adhesives, and other fields. In order to achieve excellent mechanical and heat resistance properties, polyurethane or polyurethane-urea aqueous dispersions are often designed as block polymers with larger molecular weights. However, as the molecular weight increases, the emulsion viscosity increases, resulting in poor rheological and wetting properties, thereby reducing viscosity and substrate adhesion. Currently, several methods have been proposed to improve this problem, such as the use of two-component systems, ketone-hydrazine post-crosslinking systems, silane coupling post-crosslinking, etc. The core idea is to control the molecular weight of the polyurethane or polyurethane-urea aqueous dispersion within an appropriate range, ensuring that the emulsion viscosity is as low as possible (rheological and wetting properties are as good as possible), and then increase the crosslinking degree and molecular weight of the system through the reaction of the curing agent or post-crosslinking groups in the system during bonding, thereby achieving excellent mechanical and heat resistance properties. However, the two-component system requires the use of high-cost and highly toxic polyisocyanate curing agents; the reaction rate of hydrazide and ketone groups in the ketohydrazine post-crosslinking system is slow, and the residual hydrazide is water-soluble, which will reduce the resistance; silane coupling agents are highly reactive and easily hydrolyzed, which will lead to problems such as premature reaction and decreased film-forming properties.

[0003] Chinese patent CN109897148A provides a method for preparing and applying a renewable polyurea-urethane with dynamic covalent crosslinking based on stable borate bonds. The method first preforms a cyclic borate compound with nitrogen-boron internal coordination, which is then fully reacted with an isocyanate compound to produce a PUU resin gel. The resulting gel exhibits repairability and remodelability, as well as good hydrolytic stability. However, the cyclic borate compound requires presynthesis, isolation and purification, and then introduction as a raw material into the polyurea-urethane, a relatively cumbersome process that prevents its application as a post-crosslinking structure in polymer systems.

[0004] Chinese patent CN111732701A provides a method for preparing self-healing polyurethanes based on boron-nitrogen coordination. This method incorporates a functional monomer containing a borate ester structure and an electron-rich nitrogen atom structure into the polyurethane molecular chain, resulting in a polymer material with excellent mechanical properties and good self-healing efficiency. However, the nitrogen-boron coordination occurs between molecules, which greatly limits the strength and stability of the van der Waals forces. Furthermore, the borate ester functional monomer is susceptible to hydrolysis, limiting its application in aqueous environments.

[0005] In summary, this field is currently in urgent need of waterborne polyurethanes that have excellent strength and resistance, as well as low viscosity and good wetting when used as aqueous dispersions. Summary of the Invention

[0006] The primary purpose of the present invention is to provide a post-crosslinked waterborne polyurethane, which can provide excellent strength and resistance, and has the characteristics of low viscosity and good wetting when used as an aqueous dispersion.

[0007] In order to achieve the above object of the invention, the present invention is implemented through the following technical solutions:

[0008] A post-crosslinking system waterborne polyurethane, wherein the post-crosslinking structure is achieved by a polycyclic intramolecular N→B coordinated borate ester having the following structure:

[0009]

[0010] Wherein, x is selected from an integer between 2 and 4, and y is selected from an integer between 2 and 4.

[0011] The aqueous polyurethane-polyurea prepared by the present invention contains a polycyclic intramolecular N→B coordination bond borate precursor building block at the molecular chain end, which can produce post-crosslinking between molecular chains as the moisture content decreases during the film forming and drying process. The novel post-crosslinking system aqueous polyurethane prepared by the present invention is a block polymer that mostly exists in a low molecular weight straight chain type in the aqueous dispersion state. At this time, the aqueous dispersion has a low viscosity, which meets the current downstream use conditions of adhesives while maintaining high rheological and high wetting properties, and can better wet the substrate to show viscosity; as the water evaporates during the application activation process, the polycyclic intramolecular N→B coordination bond borate precursor building block is promoted to undergo a borate esterification reaction, forming a branched crosslinking topological structure, which greatly improves its mechanical properties and durability; at the same time, due to the coordination effect between the lone pair of electrons on the nitrogen atom and the empty orbital of the boron atom, the bond length of the nitrogen-boron coordination bond is range, although longer than the nitrogen-boron covalent bond But compared to the common intermolecular nitrogen-boron coordination bond The bond length range is shorter (J.Am.Chem.Soc.2020,142,21852-21860.), so this borate post-crosslinking structure can overcome the disadvantage that general borate is easily hydrolyzed.

[0012] At the same time, the polycyclic intramolecular N→B coordination bond borate post-crosslinked structure introduced by the present invention can obtain intramolecular N→B coordination bond borate structures with different ring tensions by adjusting the carbon number of the hydroxyalkyl chain in the piperazine compound, among which the six-membered ring has the smallest ring tension (when the raw material is 1-piperazinyl propanol) and can form a stable chair conformation, further improving the stability of the borate structure; the five-membered ring (when the raw material is N-hydroxyethyl piperazine) and the seven-membered ring (when the raw material is 1-piperazinyl butanol) have comparable ring tensions, slightly higher than the six-membered ring (Chem, 2018, 4, 599-612.), so the stability of the post-crosslinked structure is slightly inferior to the former, but the branched crosslinked topology is more active, so that the cross-linked waterborne polyurethane can obtain better wettability, viscosity and viscosity maintenance time.

[0013] In the present invention, the waterborne polyurethane is prepared by reacting the following raw materials:

[0014] S1, one or more polyisocyanates;

[0015] S2, one or more macromolecular polyols having an average molecular weight of 500 to 5000 g / mol, preferably 1000 to 3000 g / mol;

[0016] S3, one or more compounds containing piperazine groups, each containing at least one group capable of reacting with an isocyanate;

[0017] S4, one or more boric acid compounds containing at least one group capable of reacting with isocyanate;

[0018] Optionally, S5, one or more polyamine small molecule chain extenders containing active hydrogen, having a molecular weight of 60 to 499 g / mol;

[0019] S6. A hydrophilic or hydrophilic potential compound containing at least one group capable of reacting with isocyanate;

[0020] S7, water;

[0021] Optionally, S8, a catalyst that catalyzes the reaction of isocyanate groups with hydroxyl groups;

[0022] S9. An organic solvent that does not contain a group that can react with isocyanate.

[0023] In the present invention, based on the total mass of components S1 to S7:

[0024] The amount of component S1 is 2.0 to 15.0 wt%, preferably 4.8 to 10.0 wt%;

[0025] The amount of component S2 is 30.0-50.0 wt%, preferably 32.5-42.5 wt%;

[0026] The amount of component S3 is 0.4 to 5.0 wt%, preferably 0.4 to 4.0 wt%;

[0027] The amount of component S4 is 0.1 to 4.0 wt%, preferably 0.1 to 1.5 wt%;

[0028] The amount of component S5 is 0-3.0 wt%, preferably 0.05-1.5 wt%;

[0029] The amount of component S6 is 0.5 to 3.0 wt%, preferably 1.0 to 2.5 wt%;

[0030] The amount of component S7 is 40.0-65.0 wt%, preferably 45.0-52.0 wt%;

[0031] Based on the total mass of components S1 to S6:

[0032] The dosage of the component S8 is 0 to 1000 ppm;

[0033] The amount of component S9 is 1.0 to 2.0 times the total mass of S1 to S6.

[0034] In the present invention, component S1 polyisocyanate includes but is not limited to one or more of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate and dicyclohexylmethane diisocyanate, preferably one or more of isophorone diisocyanate, hexamethylene diisocyanate and dicyclohexylmethane diisocyanate.

[0035] In the present invention, component S2 macromolecular polyol includes but is not limited to one or more of polyethylene glycol, polypropylene glycol, polyethylene glycol-propylene glycol, polytetramethylene ether glycol, polycaprolactone diol, polycarbonate diol, polyethylene adipate diol, poly1,4-butylene adipate diol, polyneopentyl adipate diol, poly1,6-hexanediol adipate diol and polyneopentyl adipate 1,6-hexanediol adipate diol, preferably poly1,4-butylene adipate diol and / or polyneopentyl adipate 1,6-hexanediol adipate diol.

[0036] In the present invention, the compound containing a piperazine group in component S3 includes but is not limited to one or more of N-hydroxyethylpiperazine, 1-piperazinylpropanol and 1-piperazinylbutanol, preferably 1-piperazinylpropanol.

[0037] In the present invention, the boric acid compound component S4 includes, but is not limited to, one or more of (2-aminoethyl)boric acid, (3-aminopropyl)boric acid, and (4-aminobutyl)boric acid, with (3-aminopropyl)boric acid being preferred. The structural formulas of the (2-aminoethyl)boric acid, (3-aminopropyl)boric acid, and (4-aminobutyl)boric acid are as follows:

[0038]

[0039] (2-Aminoethyl)boric acid, (3-aminopropyl)boric acid, and (4-aminobutyl)boric acid can be purchased or prepared by any available method, specifically by electrophilic addition reaction of N-allyl-N,N-bis(trimethylsilyl)amine and borane dimethyl sulfide complex (Bioorganic Chemistry, 2009, 37, 180-184).

[0040] In the present invention, component S5 contains a polyamine small molecule chain extender with active hydrogen, including but not limited to one or more of ethylenediamine, hexamethylenediamine, pentamethylenediamine, diethylenetriamine, isophoronediamine and 4,4-diphenylmethanediamine, preferably ethylenediamine and / or isophoronediamine.

[0041] In the present invention, the hydrophilic compound or the compound having hydrophilic potential of component S6 is selected from one or more of the sulfonic acid type, preferably including but not limited to 2-(2-aminoethyl) aminoethanesulfonic acid sodium, 2-(2-aminoethyl) aminopropanesulfonic acid sodium, 1,4-butanediol-2-sulfonic acid sodium and 1,2-dihydroxy-3-propanesulfonic acid sodium, more preferably 2-(2-aminoethyl) aminoethanesulfonic acid sodium. Optionally, the hydrophilic compound or the compound having hydrophilic potential, in addition to one or more of the sulfonic acid type, also includes one or more of the non-ionic type, the non-ionic type including but not limited to monohydric alcohol and / or dihydric alcohol containing polyethylene oxide segment in the main chain and / or side chain, with a molecular weight of 500 to 3000 g / mol.

[0042] In the present invention, the component S8 catalyst includes but is not limited to an organic bismuth or organic tin catalyst, preferably Bi@8108 and / or butyltin laurate from a leading American company, more preferably Bi@8108 from a leading American company.

[0043] In the present invention, the organic solvent of component S9 is a low-boiling-point organic solvent having a boiling point of 40 to 85° C., preferably acetone and / or butanone, more preferably acetone.

[0044] In the present invention, the solid content of the aqueous polyurethane is 40 to 55 wt%, preferably 45 to 50 wt%.

[0045] In the present invention, the average particle size of the solid content is 130 to 300 nm, preferably 150 to 230 nm.

[0046] Another object of the present invention is to provide a method for preparing the waterborne polyurethane.

[0047] A method for preparing waterborne polyurethane, comprising the following steps:

[0048] Step (1-1): Component S1, component S2, component S8, and part of component S9 are mixed and reacted until the NCO content reaches the theoretical value to generate a diisocyanate-terminated prepolymer;

[0049] Step (1-2): Cool the diisocyanate-terminated prepolymer, add the remaining portion of component S9, dissolve and dilute, add components S5 and S6 to react, then add components S3 and S4, continue to react, and then add S7 to shear and disperse to obtain an emulsion, remove the solvent, and obtain an aqueous polyurethane emulsion.

[0050] In the present invention, the reaction temperature of step (1-1) is 75-85°C.

[0051] In the present invention, in the steps (1-2) and (1-1), the mass ratio of component S9 added is 5 to 12:1.

[0052] In the present invention, in step (1-2), the pH value of the emulsion obtained is greater than 7.

[0053] In the present invention, in step (1-2), the components S5 and S6 are aqueous solutions, and the amount of water used is 3 to 5 times the total mass of the components S5 and S6.

[0054] In the present invention, in step (1-2), the components S3 and S4 are aqueous solutions, and the amount of water used is 2 to 5 times the total mass of the components S3 and S4.

[0055] In the present invention, in step (1-2), the prepolymer is cooled to 50-60°C.

[0056] In the present invention, in step (1-2), the components S5 and S6 are added and reacted at 35-45° C. for 5-10 minutes.

[0057] In the present invention, in step (1-2), the components S3 and S4 are added and reacted at 35-45° C. for 5-10 minutes.

[0058] Another object of the present invention is to provide uses of the waterborne polyurethane.

[0059] A use of waterborne polyurethane, wherein the waterborne polyurethane is the waterborne polyurethane described above, or the waterborne polyurethane prepared by the method described above, and is used in the fields of shoe glue, automobile interior glue, and electronic glue.

[0060] In an application example of the present invention, a water-based shoe glue is provided, which comprises the water-based polyurethane of the present invention in a mass percentage range of 70-95%. Furthermore, the water-based shoe glue further comprises other additives, such as a wetting agent, a defoaming agent, a thickener, and water.

[0061] Compared with the prior art, the present invention has the following positive effects:

[0062] (1) The initial strength is fast and high, reaching 2.3 N / mm in 3 minutes (Example 1). At the same time, the initial heat resistance is excellent, and the debonding length of the 15-minute specimen at 80°C for 1 hour is only 3 mm (Example 1);

[0063] (2) The late-stage strength is high and the late-stage heat resistance can achieve a debonding performance within 10 mm in all embodiments. More importantly, the more demanding late-stage moisture-heat resistance can also achieve a debonding performance of 3 mm at best (Example 1).

[0064] (3) The production process is simple, easy to operate, safe and non-toxic. DETAILED DESCRIPTION

[0065] 1. Sources of main raw materials in the embodiment:

[0066] Polyester polyol I: polybutylene adipate diol, Mn = 2000 g / mol, ( WHP-204, Wanhua Chemical);

[0067] Polyester polyol II: polybutylene adipate diol, Mn = 3000 g / mol, ( WHP-304, Wanhua Chemical);

[0068] Catalyst: Bi@8108, Leading Technologies, Inc.

[0069] Acetone: industrial grade, Wanhua Chemical Group Co., Ltd.

[0070] Hexamethylene diisocyanate (HDI): industrial grade, Wanhua Chemical Group Co., Ltd.

[0071] Isophorone diisocyanate (IPDI): industrial grade, Wanhua Chemical Group Co., Ltd.

[0072] Ethylenediamine: analytical grade, Sinopharm Chemical Reagent Co., Ltd.;

[0073] A95: aminoalkylsulfonate hydrophilic chain extender, Evonik Chemical Co., Ltd.

[0074] N-Hydroxyethylpiperazine: industrial grade, Shanghai Haiqu Chemical Co., Ltd.;

[0075] 1-Piperazinylpropanol: reagent grade, Shanghai Bid Pharmaceutical Technology Co., Ltd.;

[0076] 1-Piperazinylbutanol: industrial grade, Nanjing Kangmanlin Industrial Chemical Co., Ltd.;

[0077] Aminomethylboric acid: reagent grade, Shenzhen Aituo Chemical Co., Ltd.;

[0078] (2-Aminoethyl)boric acid: reagent grade, Suzhou Amate Biotechnology Co., Ltd.;

[0079] (3-Aminopropyl)boric acid: Preparation method: Under nitrogen atmosphere, dissolve 20.1g of N-allyl-N,N-bis(trimethylsilyl)amine and 7.7g of borane dimethyl sulfide complex in 500mL of dichloromethane, stir at room temperature for 1h, remove dichloromethane by vacuum distillation, dissolve the solid matter in the flask in 200mL of tetrahydrofuran, add 10g of water, stir at room temperature for 2h, remove tetrahydrofuran by vacuum distillation, add

[0080] Add 100 mL of ether to precipitate (3-aminopropyl)boric acid;

[0081] Tween 20: reagent grade, Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0082] Other raw materials were purchased from the market unless otherwise specified.

[0083] Particle size testing instrument: Malvern particle size analyzer, model: Nano-ZS90.

[0084] Particle size test method: add a drop of emulsion to 100g of deionized water, stir, inject into the particle size analyzer cuvette (3-5cm high), place it in the Malvern particle size analyzer for testing, and take the average of three test results.

[0085] Solid content test method: Take an appropriate amount of emulsion in a container made of tin foil, weigh the weight change before and after 20 minutes at 150 degrees, and calculate its solid content.

[0086] Example 1

[0087] 1) 429 g of dehydrated WHP-204, 53 g of HDI, 100 g of acetone, and 0.13 g of Bi@8108 were added to a 1 L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and the mixture was stirred at 75° C. until the NCO content reached 1.46%.

[0088] 2) The prepolymer was cooled to 50° C. and dissolved in 500 g of acetone and cooled to 35° C. 0.8 g of ethylenediamine and 12.8 g of A95 in 40 g of aqueous solution were added and stirred for 10 min. Then, 14.6 g of 1-piperazinylpropanol and 4.73 g of (3-aminopropyl)boric acid in 38.6 g of aqueous solution were added and stirring was continued for 10 min.

[0089] 3) 540 g of water was added to the mixture in step 2) and the mixture was dispersed. After separating the acetone by distillation, 4 g of emulsifier Tween 20 was added, and additional water was added to adjust the solids content. This resulted in a solvent-free aqueous polyurethane emulsion having a solids content of 45 wt %, an average particle size of 173 nm in the dispersed phase as measured by laser correlation (laser particle size analyzer), and a pH of 7.0.

[0090] Example 2

[0091] 1) 429 g of dehydrated WHP-204, 47.7 g of HDI, 7.0 g of IPDI, 100 g of acetone, and 0.044 g of Bi@8108 were added to a 1 L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and the mixture was stirred at 75° C. until the NCO content reached 1.46%.

[0092] 2) The prepolymer was cooled to 50°C and dissolved in 500g of acetone and cooled to 45°C. 0.8g of ethylenediamine and 12.8g of A95 in 40g of aqueous solution were added and stirred for 5min. The mixture was then cooled to 35°C and 6.0g of N-hydroxyethylpiperazine and 4.71g of (3-aminopropyl)boric acid in 53.4g of aqueous solution were added and stirred for 10min.

[0093] 3) 540 g of water was added to the mixture in step 2) and the mixture was dispersed. After separating the acetone by distillation, 4 g of emulsifier Tween 20 was added, and additional water was added to adjust the solids content. This resulted in a solvent-free aqueous polyurethane emulsion having a solids content of 44 wt %, an average particle size of 179 nm in the dispersed phase as measured by laser correlation (laser particle size analyzer), and a pH of 7.1.

[0094] Example 3

[0095] 1) 429.3 g of dehydrated WHP-204, 64.4 g of WHP-304, 122 g of HDI, 50 g of acetone, and 0.39 g of Bi@8108 were added to a 1 L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and the mixture was stirred at 85° C. until the NCO content reached 6.18%.

[0096] 2) The prepolymer was cooled to 60°C and dissolved in 500g of acetone and cooled to 35°C. 20g of ethylenediamine and 30g of A95 in 150g of aqueous solution were added and stirred for 10min. The mixture was then heated to 45°C and 68g of 1-piperazinylpropanol and 21g of (2-aminoethyl)boric acid in 178g of aqueous solution were added and stirred for 10min.

[0097] 3) 680 g of water was added to the mixture in step 2) and the mixture was dispersed. After separating the acetone by distillation, 4 g of emulsifier Tween 20 was added, and additional water was added to adjust the solids content. This resulted in a solvent-free aqueous polyurethane emulsion having a solids content of 42.3 wt %, an average particle size of 152 nm in the dispersed phase as measured by laser correlation (laser particle size analyzer), and a pH of 7.0.

[0098] Example 4

[0099] 1) 429 g of dehydrated WHP-204, 53 g of HDI, 100 g of acetone, and 0.13 g of Bi@8108 were added to a 1 L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and the mixture was stirred at 75° C. until the NCO content reached 1.46%.

[0100] 2) The prepolymer was cooled to 50° C. and dissolved in 500 g of acetone and cooled to 35° C. 0.8 g of ethylenediamine and 12.8 g of A95 in 68 g of aqueous solution were added and stirred for 10 min. Then, 54.9 g of 1-piperazinylbutanol and 45.2 g of (2-aminoethyl)boric acid in 200 g of aqueous solution were added and stirring was continued for 5 min.

[0101] 3) 600 g of water was added to the mixture in step 2) and the mixture was dispersed. After separating the acetone by distillation, 4 g of emulsifier Tween 20 was added, and additional water was added to adjust the solids content. This resulted in a solvent-free aqueous polyurethane emulsion having a solids content of 40 wt %, an average particle size of 220 nm in the dispersed phase as measured by laser correlation (laser particle size analyzer), and a pH of 7.4.

[0102] Example 5

[0103] 1) 386.4 g of dehydrated WHP-204, 64.4 g of WHP-304, 47.7 g of HDI, 7.0 g of IPDI, 100 g of acetone, and 0.13 g of Bi@8108 were added to a 1 L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and the mixture was stirred at 75° C. until the NCO content reached 1.41%.

[0104] 2) The prepolymer was cooled to 50° C. and dissolved in 500 g of acetone and cooled to 35° C. 0.8 g of ethylenediamine and 12.8 g of A95 in 40 g of aqueous solution were added and stirred for 10 min. Then, 40.4 g of 1-piperazinylpropanol and 1.81 g of (3-aminopropyl)boric acid in 84.4 g of aqueous solution were added and stirring was continued for 10 min.

[0105] 3) 460 g of water was added to the mixture in step 2) and the mixture was dispersed. After separating the acetone by distillation, 4 g of emulsifier Tween 20 was added, and additional water was added to adjust the solids content. This resulted in a solvent-free aqueous polyurethane emulsion having a solids content of 50 wt %, an average particle size of 170 nm in the dispersed phase as measured by laser correlation (laser particle size analyzer), and a pH of 7.0.

[0106] Comparative Example 1

[0107] An aqueous polyurethane dispersion was prepared according to the steps of Example 1, except that in step 2), 40 g of an aqueous solution of 0.8 g of ethylenediamine and 12.8 g of A95 was added and stirred for 10 min, followed by the addition of 7.7 g of an aqueous solution of 2.9 g of 1-piperazinylpropanol and 0.9 g of (3-aminopropyl)boric acid, and continued stirring for 10 min to obtain an aqueous polyurethane emulsion having an average particle size of 186 nm and a pH of 7.4.

[0108] Comparative Example 2

[0109] An aqueous polyurethane dispersion was prepared according to the steps of Example 1, except that in step 2), 0.8 g of ethylenediamine and 12.8 g of A95 were added to 40 g of an aqueous solution and stirred for 10 min, followed by the addition of 58.3 g of 1-piperazinylpropanol and 154.5 g of an aqueous solution of 18.9 g of (3-aminopropyl)boric acid, and stirring was continued for 10 min to obtain an aqueous polyurethane emulsion having an average particle size of 168 nm and a pH of 7.0.

[0110] Comparative Example 3

[0111] An aqueous polyurethane dispersion was prepared according to the steps of Example 1, except that in step 2), 0.8 g of ethylenediamine and 12.8 g of A95 were added to 40 g of an aqueous solution and stirred for 20 min to obtain an aqueous polyurethane emulsion having an average particle size of 183 nm and a pH of 7.5.

[0112] Preparation of adhesive:

[0113] 100 g of each of the above examples and comparative examples were taken, placed in a steel cup, marked, and 0.2% wetting agent (TEGO-KL245, Evonik, Germany), 0.05% defoaming agent (BYK024, Germany), and 0.3% thickener (Vesmody U604, Wanhua Chemical) were added, and stirred for use.

[0114] Test substrate: 2cm×100cm rubber strip

[0115] Specimen preparation:

[0116] Double-sided adhesive: 100g / m 2 , drying in a 65℃ oven for 3 minutes, and pressing at 0.1MPa for 10 seconds.

[0117] Performance testing:

[0118] 3-min strength: After the specimen is prepared, the peel strength is tested within 3 minutes at 25°C, 180°, and a tensile rate of 200 mm / min.

[0119] Later strength: After the specimens were prepared, they were cured at 25°C for 24 hours and then the peel strength was tested at 180° and a tensile rate of 200 mm / min.

[0120] Initial heat resistance: After the specimen is prepared, place it at 25°C for 15 minutes, then at 180°, 80°C×200g×1h, and measure the debonding length within 1h.

[0121] Later heat resistance: After the specimen is prepared, it is cured at 25°C for 24 hours, then tested at 180°, 80°C×500g×1h, and the debonding length within 1 hour is measured.

[0122] Later resistance to moisture and heat: After the specimen is prepared, it is cured at 25°C for 24 hours, then tested at 180°, 80°C×40% humidity×200g×1h, and the debonding length within 1 hour is measured.

[0123] Performance test of embodiments and comparative examples

[0124] 3min strength (N / mm) Later strength (N / mm) Initial heat resistance Late heat resistance Late resistance to humidity and heat Example 1 2.3 4.6 3mm 2mm 3mm Example 2 1.8 4.4 6mm 6mm 7mm Example 3 2.5 4.4 5mm 6mm 6mm Example 4 1.5 5.0 6mm 8mm 11mm Example 5 1.7 4.8 9mm 7mm 8mm Comparative Example 1 2.0 3.0 8mm 12mm 17mm Comparative Example 2 0.9 4.0 14mm 9mm 12mm Comparative Example 3 2.4 2.9 11mm 16mm 26mm

Claims

1. A post-crosslinking system waterborne polyurethane, characterized in that: The post-crosslinking system is achieved by a polycyclic intramolecular N→B coordinated borate ester with the following structure: Wherein, x is selected from an integer between 2 and 4, and y is selected from an integer between 2 and 4.

2. The waterborne polyurethane according to claim 1, wherein The aqueous polyurethane dispersion is prepared by reacting the following raw materials: S1, one or more polyisocyanates; S2, one or more macromolecular polyols having an average molecular weight of 500 to 5000 g / mol; S3, one or more compounds containing piperazine groups, each containing at least one group capable of reacting with an isocyanate; S4, one or more boric acid compounds containing at least one group capable of reacting with isocyanate; Optionally, S5, one or more polyamine small molecule chain extenders containing active hydrogen, having a molecular weight of 60 to 499 g / mol; S6. A hydrophilic or hydrophilic potential compound containing at least one group capable of reacting with isocyanate; S7, water; Optionally, S8, a catalyst that catalyzes the reaction of isocyanate groups with hydroxyl groups; S9. An organic solvent that does not contain a group that can react with isocyanate.

3. The aqueous polyurethane according to claim 2, wherein In the aqueous polyurethane dispersion, S2 has an average molecular weight of 1000 to 3000 g / mol.

4. The aqueous polyurethane according to claim 1 or 2, characterized in that Based on the total mass of components S1 to S7: The amount of component S1 is 2.0 to 15.0 wt%; The amount of component S2 is 30.0 to 50.0 wt%; The amount of component S3 is 0.4-5.0 wt%; The amount of component S4 is 0.1 to 4.0 wt%; The amount of component S5 is 0 to 3.0 wt%; The amount of component S6 is 0.5 to 3.0 wt%; The amount of component S7 is 40.0 to 65.0 wt%; Based on the total mass of components S1 to S6: The dosage of the component S8 is 0 to 1000 ppm; The amount of component S9 is 1.0 to 2.0 times the total mass of S1 to S6.

5. The waterborne polyurethane according to claim 4, characterized in that Based on the total mass of components S1 to S7: The amount of component S1 is 4.8-10.0 wt%; The amount of component S2 is 32.5-42.5 wt%; The amount of component S3 is 0.4-4.0 wt%; The amount of component S4 is 0.1 to 1.5 wt%; The amount of component S5 is 0.05 to 1.5 wt%; The amount of component S6 is 1.0 to 2.5 wt%; The amount of component S7 is 45.0-52.0 wt%.

6. The aqueous polyurethane according to claim 1 or 2, characterized in that Component S1 polyisocyanate, including one or more of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate and dicyclohexylmethane diisocyanate; and / or Component S2 macromolecular polyols, including one or more of polyethylene glycol, polypropylene glycol, polyethylene glycol-propylene glycol, polytetramethylene glycol, polycaprolactone diol, polycarbonate diol, polyethylene adipate diol, polybutylene adipate diol, polyneopentyl adipate diol, polyhexanediol adipate diol and polyneopentyl adipate 1,6-hexanediol diol; and / or Component S3 contains compounds of piperazine groups, including one or more of N-hydroxyethylpiperazine, 1-piperazinylpropanol and 1-piperazinylbutanol.

7. The waterborne polyurethane according to claim 6, characterized in that Component S1 polyisocyanate, including one or more of isophorone diisocyanate, hexamethylene diisocyanate and dicyclohexylmethane diisocyanate; and / or Component S2 macromolecular polyol, including poly 1,4-butylene adipate diol and / or poly neopentyl adipate 1,6-hexanediol diol; and / or Component S3 contains compounds containing piperazine groups, including 1-piperazinylpropanol.

8. The aqueous polyurethane according to claim 1 or 2, characterized in that Component S4 boric acid compounds, including one or more of (2-aminoethyl)boric acid, (3-aminopropyl)boric acid, (4-aminobutyl)boric acid; and / or Component S5: a polyamine small molecule chain extender containing active hydrogen, including one or more of ethylenediamine, hexamethylenediamine, pentamethylenediamine, diethylenetriamine, isophoronediamine and 4,4-diphenylmethanediamine; and / or Component S6 is a hydrophilic compound or a compound with hydrophilic potential, selected from one or more sulfonic acid type compounds; and / or Component S8 catalyst, including an organobismuth or organotin catalyst; and / or The organic solvent of component S9 is a low-boiling-point organic solvent having a boiling point of 40 to 85°C.

9. The waterborne polyurethane according to claim 8, characterized in that Component S4 boric acid compounds, including (3-aminopropyl)boric acid; and / or Component S5: a polyamine small molecule chain extender containing active hydrogen, including ethylenediamine and / or isophoronediamine; and / or Component S6 is a hydrophilic compound or a compound with hydrophilic potential, including one or more of sodium 2-(2-aminoethyl)aminoethanesulfonate, sodium 2-(2-aminoethyl)aminopropanesulfonate, sodium 1,4-butanediol-2-sulfonate and sodium 1,2-dihydroxy-3-propanesulfonate; and / or Component S8 catalyst, including leading American companies 8108 and / or butyltin laurate; and / or The organic solvent of component S9 is acetone and / or butanone.

10. The waterborne polyurethane according to claim 9, characterized in that Component S6 is a hydrophilic compound or a compound with hydrophilic potential, selected from sodium 2-(2-aminoethyl)aminoethanesulfonate; and / or Component S8 catalyst, including leading American companies 8108; and / or The organic solvent of component S9 is acetone.

11. The aqueous polyurethane according to claim 1 or 2, characterized in that The solid content of the aqueous polyurethane is 40 to 55 wt%; and / or The average particle size of the solid content is 130 to 300 nm.

12. The waterborne polyurethane according to claim 11, characterized in that The solid content of the aqueous polyurethane is 45 to 50 wt%; and / or The average particle size of the solid content is 150 to 230 nm.

13. A method for preparing waterborne polyurethane, wherein the method is for preparing the waterborne polyurethane according to any one of claims 1 to 12, characterized in that: The method comprises the following steps: Step (1-1): Component S1, component S2, component S8, and part of component S9 are mixed and reacted until the NCO content reaches the theoretical value to generate a diisocyanate-terminated prepolymer; Step (1-2): Cool the diisocyanate-terminated prepolymer, add the remaining portion of component S9, dissolve and dilute, add components S5 and S6 to react, then add components S3 and S4, continue to react, and then add S7 to shear and disperse to obtain an emulsion, remove the solvent, and obtain an aqueous polyurethane emulsion.

14. The preparation method according to claim 13, characterized in that The reaction temperature of step (1-1) is 75-85°C.

15. The preparation method according to claim 13, characterized in that In the steps (1-2) and (1-1), the mass ratio of component S9 added is 5 to 12:1; and / or In step (1-2), the pH value of the obtained emulsion is greater than 7; and / or In step (1-2), the components S5 and S6 are aqueous solutions, and the amount of water used is 3 to 5 times the total mass of the components S5 and S6; and / or In step (1-2), the components S3 and S4 are aqueous solutions, and the amount of water used is 2 to 5 times the total mass of the components S3 and S4; and / or In step (1-2), the prepolymer is cooled to 50-60°C; and / or In step (1-2), the reaction is carried out at 35-45° C. for 5-10 minutes after adding component S5 and component S6; and / or In step (1-2), after adding component S3 and component S4, the mixture is reacted at 35-45° C. for 5-10 minutes.

16. Use of a waterborne polyurethane, wherein the waterborne polyurethane is the waterborne polyurethane according to any one of claims 1 to 12, or the waterborne polyurethane prepared by the method according to any one of claims 13 to 15, and the use is in the fields of shoe glue, automobile interior glue, and electronic glue.

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