Aqueous non-isocyanate polyurethane coating and method for its preparation

Abstract

This invention discloses a method for preparing a waterborne non-isocyanate polyurethane coating, comprising the following steps: (1) Preparation of waterborne cyclic carbonate resin: adding polycyclic carbonate to an organic solvent, then adding aminosulfonic acid and reacting at 45-55°C, adding N,N-dimethylcyclohexylamine for neutralization, and continuing the reaction at 120-150°C to obtain a waterborne cyclic carbonate resin, then adding water for dispersion to obtain a waterborne cyclic carbonate emulsion; (2) Preparation of waterborne non-isocyanate polyurethane coating: stirring the waterborne cyclic carbonate emulsion, polyamine curing agent, and defoamer at 20-30°C until uniform, spraying to form a film, baking and curing to obtain a non-isocyanate polyurethane coating. This invention also discloses the waterborne non-isocyanate polyurethane coating obtained by the above preparation method. The waterborne non-isocyanate polyurethane coating of this invention is easy to waterborne, has a low synthesis reaction temperature, and has the advantages of safety, environmental protection, and energy saving.

Description

Technical Field

[0001] This invention relates to the field of non-isocyanate polyurethane coating technology, and particularly to a water-based non-isocyanate polyurethane coating and its preparation method. Background Technology

[0002] Polyurethane (PU) is a general term for a class of polymers containing urethane bonds. It possesses excellent physical and mechanical properties and chemical resistance, and is mainly used as flexible and rigid foams, synthetic resins, adhesives, sealants, and coatings, with widespread applications in biomedicine, textiles, construction, packaging, and automotive industries. However, traditional polyurethane is produced by the condensation polymerization of diisocyanates and polyols. The diisocyanate raw material is prepared using the toxic and harmful phosgene process, which is not environmentally friendly. Furthermore, polymers containing isocyanate groups are sensitive to moisture, necessitating the isolation of polyurethane products from moisture during production, storage, transportation, and use, increasing costs. These issues have prompted the search for environmentally friendly and sustainable alternatives to produce polyurethane.

[0003] Non-isocyanate polyurethane (NIPU) is synthesized by polymerizing polycyclic carbonates (usually five-membered ring carbonates) and polyamines. The cyclic carbonates are typically obtained through the addition reaction of CO2 with epoxides. In addition to urethane bonds, the NIPU molecule contains hydroxyl groups, giving it richer intermolecular forces such as hydrogen bonds. Therefore, NIPU exhibits superior chemical and heat resistance compared to traditional polyurethanes. The preparation of NIPU avoids the use of hazardous precursors of isocyanate-based chemicals and significantly reduces its sensitivity to water. Therefore, the synthesis of NIPU conforms to the standards of "green chemistry" and solves the pollution problems associated with traditional polyurethane material preparation processes.

[0004] Existing cyclic carbonate resins and NIPU coatings often use large amounts of the organic solvent N,N-dimethylformamide (DMF), which is toxic. Therefore, the development direction of NIPU is to prepare waterborne cyclic carbonates and waterborne NIPUs that avoid the use of DMF.

[0005] Chinese invention patent application CN113912839A discloses a method for preparing waterborne non-isocyanate polyurethane prepolymers and coatings. The method involves first preparing a carbamate-containing intermediate by ring-opening of ethylene carbonate and a diamine, then reacting itaconic acid to introduce vinyl and carboxyl groups. Next, it reacts with the reaction product of diaminoethyl methacrylate and thioglycerol to introduce N,N-dimethylsulfur-containing alkyl chains. Finally, it grafts polyacrylate segments onto the polyacrylate monomer via free radical polymerization, and finally quaternizes the polyacrylate to prepare a cationic waterborne NIPU. This method requires multiple esterification reactions of hydroxyl and carboxyl groups, reacting at a high temperature of 160°C for more than 4 hours, and requires organotin catalysts such as dibutyltin dilaurate, which is toxic. This method requires four steps and the yield cannot be guaranteed, making it difficult to achieve large-scale production applications. Chinese invention patent application CN108546262A discloses a waterborne sorbitan cyclic carbonate emulsion, its preparation method, and its application in waterborne non-isocyanate polyurethane coatings. The method for preparing the waterborne sorbitan cyclic carbonate emulsion involves adding sorbitan-based cyclic carbonate to a reaction vessel, adding an acid anhydride, reacting at 80-120℃ for 6-20 hours until the acid value is below 30 mg KOH / g, cooling to below 50℃, adding acetone to reduce viscosity, adding a neutralizing agent for neutralization, emulsifying with water, and then removing the acetone to obtain a waterborne sorbitan-based cyclic carbonate emulsion with a solid content of 20-50%. This method involves the ring-opening reaction of the hydroxyl groups on the sorbitan cyclic carbonate molecular chain with the acid anhydride, introducing carboxyl groups onto the sorbitan-based cyclic carbonate molecule, neutralizing to form a salt, and preparing anionic carboxylic acid salt water-based cyclic carbonate emulsion, which is not easily waterborne. Summary of the Invention

[0006] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the purpose of this invention is to provide a method for preparing waterborne non-isocyanate polyurethane coatings. The waterborne non-isocyanate polyurethane coatings prepared are easy to waterborne, have a low synthesis reaction temperature, and have the advantages of safety, environmental protection and energy saving.

[0007] Another object of the present invention is to provide a waterborne non-isocyanate polyurethane coating prepared by the above-mentioned method for preparing waterborne non-isocyanate polyurethane coatings.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A method for preparing a waterborne non-isocyanate polyurethane coating includes the following steps:

[0010] (1) Preparation of waterborne cyclic carbonate resin: Add polycyclic carbonate to an organic solvent, then add aminosulfonic acid to react, react at 45-55℃ for 0.5-1 hour, add N,N-dimethylcyclohexylamine to neutralize, continue to react at 120-150℃ for 5-8 hours, then add water to disperse to obtain waterborne cyclic carbonate resin.

[0011] (2) Preparation of waterborne non-isocyanate polyurethane coating: The waterborne cyclic carbonate resin, polyamine curing agent and defoamer prepared in step (1) are stirred evenly at 20-30℃, sprayed to form a film, and baked at 100-150℃ for 2-5 hours to cure, thereby obtaining non-isocyanate polyurethane coating.

[0012] Preferably, the polycyclic carbonate in step (1) is at least one of trimethylolpropane tricyclic carbonate, pentaerythritol tetracyclic carbonate, and sorbitol tetracyclic carbonate.

[0013] Preferably, the aminosulfonic acid in step (1) is one of 2-aminoethanesulfonic acid, 3-amino-1-propanesulfonic acid, 3-aminobutyric acid and 3-aminobenzenesulfonic acid.

[0014] Preferably, the molar ratio of the amino group in the aminosulfonic acid to the carbonate group in the polycyclic carbonate in step (1) is 1:2 to 6.

[0015] Preferably, the mass of the N,N-dimethylcyclohexylamine is 1 to 1.5 times the mass of the aminosulfonic acid.

[0016] Preferably, the polyamine curing agent in step (2) is one or two of 1,4-butanediamine, 1,6-hexanediamine, 1,8-octanediamine, isophorone diamine (IPDA), diethylenetriamine, and triethylenetetramine.

[0017] Preferably, the defoamer in step (2) is at least one of BYK-R605, TEGO Airex 900, and TEGO Airex 962, with a mass fraction of 0.5% to 2% of the total mass of the raw materials.

[0018] Preferably, the organic solvent in step (2) is at least one of acetone and butanone.

[0019] A waterborne non-isocyanate polyurethane coating is prepared by the method described above.

[0020] A method for preparing an aqueous cyclic carbonate resin includes the following steps:

[0021] Polycyclic carbonate is added to an organic solvent, followed by the addition of aminosulfonic acid for reaction. After reacting at 45–55°C for 0.5–1 hour, N,N-dimethylcyclohexylamine is added for neutralization, and the reaction is continued at 120–150°C for 5–8 hours to obtain an aqueous cyclic carbonate resin.

[0022] The polycyclic carbonate is at least one of trimethylolpropane tricyclic carbonate, pentaerythritol tetracyclic carbonate, and sorbitol tetracyclic carbonate;

[0023] The aminosulfonic acid mentioned is one of 2-aminoethanesulfonic acid, 3-amino-1-propanesulfonic acid, 3-aminobutyric acid, and 3-aminobenzenesulfonic acid.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] (1) The method for preparing waterborne non-isocyanate polyurethane coating of the present invention uses polycyclic cyclic carbonate compound and aminosulfonic acid as raw materials. The hydrophilic sulfonic acid group is introduced into the polycyclic cyclic carbonate compound through the reaction of cyclic carbonate group and amine group. After water dispersion, waterborne cyclic carbonate resin is prepared. After curing, waterborne NIPU is obtained. The raw materials are widely available, waterborne conversion is easy, and the synthesis reaction temperature is low. It has the advantages of safety, environmental protection and energy saving.

[0026] (2) The method for preparing the waterborne cyclic carbonate resin of the present invention can synthesize a waterborne cyclic carbonate emulsion that can be used with different curing agents to prepare a non-isocyanate polyurethane coating. The cured coating film has good hardness, high flexibility and excellent adhesion, and can be used for coating and protection of metal surfaces. Attached Figure Description

[0027] Figure 1 The infrared spectra of aqueous pentaerythritol aminobenzenesulfonic acid cyclic carbonate and pentaerythritol tetracyclic carbonate prepared in Example 1 of the present invention are shown, wherein a: aqueous pentaerythritol aminobenzenesulfonic acid cyclic carbonate; b: pentaerythritol tetracyclic carbonate.

[0028] Figure 2 This is a particle size distribution diagram of the 1:1 aqueous pentaerythritol aminobenzenesulfonic acid emulsion of Example 1 of the present invention. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0030] The coating properties were tested according to GB / T 9754-2007, GB / T 6739-2006, GB / T 1731-1993, GB / T20624.2-2006, and GB / T 9286-1998, respectively, for gloss, pencil hardness, flexibility, impact resistance, and adhesion. High-grade drawing pencils were used, manufactured by Shanghai China Pencil Factory No. 1, and all instruments were manufactured by Tianjin Jingke Materials Testing Machine Factory. A Malvern particle size analyzer was used to test the emulsion particle size and zeta potential.

[0031] Example 1

[0032] This embodiment provides a method for preparing waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate resin and waterborne pentaerythritol non-isocyanate polyurethane coating, comprising the following steps:

[0033] (1) Preparation of waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate resin: Pentaerythritol tetracyclic carbonate compound was added to a round-bottom flask, followed by acetone (10% by mass of the pentaerythritol tetracyclic carbonate compound), and 3-aminobenzenesulfonic acid (the molar ratio of amino groups to cyclic carbonate groups was 1:3). The reaction temperature was 50℃, and the reaction was carried out for 0.5 h. Then, N,N-dimethylcyclohexylamine (1.5 times the mass of 3-aminobenzenesulfonic acid) was added dropwise for neutralization. The reaction temperature was 150℃, and the reaction was carried out for 5 h to obtain waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate resin. When the temperature dropped to 80℃, water was added dropwise with rapid stirring to obtain an aqueous emulsion, which was a brownish-brown viscous liquid with a solid content of 45%, a viscosity of 500 mPa·s, and a storage stability of more than 1 year.

[0034] (2) The waterborne pentaerythritol non-isocyanate polyurethane coating was prepared by the following steps: The waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate emulsion prepared in Example 1 was further used to prepare the waterborne non-isocyanate polyurethane coating (NIPU-1): According to the formula in Table 1, the above-mentioned waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate emulsion, isophorone diamine curing agent, and defoamer were stirred evenly at room temperature and then sprayed. The ratio of primary amine to cyclic carbonate functional groups was 1:1, and the coating was cured at 120°C for 2 hours.

[0035] Table 1 Raw materials and their usage

[0036] Serial Number composition weight fraction / % 1 1:3 Waterborne Pentaerythritol Aminobenzenesulfonic Acid Cyclocarbonate Emulsion 85 2 Isophorone diamine 14.5 3 Defoamer BYK-R605 0.5 4 total 100

[0037] The coating properties obtained above are similar to those of Covestro Arcol Polyol 3553 polyester polyol (curing agent is Duranate manufactured by Asahi Kasei Corporation of Japan). TM Two-component polyurethane coatings prepared with HDI and Dow epoxy resin DER TM The performance comparison of 331 coatings is shown in Table 2 below:

[0038] Table 2 Coating performance test results

[0039] Testing items Two-component polyurethane <![CDATA[D.E.R TM 331]]> Example 1 Detection methods Gloss (60°) 96 97 97 GB / T 9754-2007 Pencil hardness 2H 2H 2H GB / T 6739-2006 Impact strength / cm 50 10 60 GB / T 1732-1993 Adhesion strength / grade (cross-cut test) 1 1 0 GB / T 9286-1998 Flexibility / mm 0.5 1 0.5 ISO 1519:2011

[0040] The prepared aqueous pentaerythritol aminobenzenesulfonic acid cyclic carbonate was characterized using a Spectrum 2000 Fourier transform infrared spectrometer, and its infrared spectrum was obtained, as shown below. Figure 1 As shown, at 1600cm -1 A new characteristic peak was generated at 1726 cm⁻¹, belonging to the benzene ring skeleton vibration. -1A new characteristic peak was generated, which belongs to the C=O vibration in the carbamate group, indicating that aminobenzenesulfonic acid has been successfully incorporated into pentaerythritol cyclic carbonate. Figure 2 The particle size distribution of the aqueous cyclic carbonate shows that its average particle size is 200 nm, its zeta potential is -47 mV, and its storage stability is over 1 year.

[0041] Table 2 shows that the waterborne pentaerythritol non-isocyanate polyurethane coating of this invention has high gloss; compared with two-component polyurethane, this invention has better performance in gloss, impact strength and adhesion; compared with epoxy resin DER TM 331 exhibits superior adhesion and flexibility. On one hand, this coating uses water as the solvent for the emulsion, reducing VOC emissions; on the other hand, the cured film possesses good hardness, high flexibility, and excellent adhesion, making it suitable for coating and protecting metal surfaces.

[0042] This invention introduces hydrophilic sulfonic acid groups into the molecular chain of a polycyclic cyclic carbonate (PCC) through the reaction of PCC groups with amine groups. The PCC is then dispersed in water to prepare an aqueous PCC, which is subsequently cured with a polyamine to synthesize an aqueous NIPU. The entire process is a two-step reaction. Compared with patent CN113912839A, this invention has a simpler preparation process, produces a product with superior performance, and is easily industrialized. Compared with patent CN108546262A, this invention does not require the presence of hydroxyl groups on the PCC, and only requires the introduction of a very small amount of sulfonate salt to facilitate aqueous production. This is because sulfonates have better hydrophilicity than carboxylates. This invention also allows for a wider selection of raw materials; the method can be used for any PCC containing ternary or higher PCCs.

[0043] Example 2

[0044] This embodiment provides a method for preparing waterborne trimethylolpropane aminopropanesulfonic acid cyclic carbonate resin and waterborne trimethylolpropane non-isocyanate polyurethane coating, comprising the following steps:

[0045] (1) Preparation of waterborne trimethylolpropane aminopropanesulfonic acid cyclic carbonate resin: Trimethylolpropane tricyclic carbonate compound was added to a round-bottom flask, followed by 10% (by weight) of butanone and 3-amino-1-propanesulfonic acid, wherein the molar ratio of amino groups to cyclic carbonate groups was 1:2. The reaction temperature was 50℃, and the reaction was carried out for 0.5 h. Then, N,N-dimethylcyclohexylamine, at 1.3 times the mass of 3-amino-1-propanesulfonic acid, was added dropwise for neutralization. The reaction temperature was 140℃, and the reaction was carried out for 6 h to obtain waterborne trimethylolpropane aminopropanesulfonic acid cyclic carbonate resin. When the temperature dropped to 80℃, water was added dropwise with rapid stirring to obtain a waterborne trimethylolpropane aminopropanesulfonic acid cyclic carbonate emulsion, which was a brownish-brown viscous liquid with a solid content of 50%, a viscosity of 1000 mPa·s, and a storage stability of more than 1 year.

[0046] (2) The waterborne trimethylolpropane NIPU coating was prepared by the following steps: The waterborne trimethylolpropane aminopropane cyclic carbonate emulsion prepared in Example 2 was further used to prepare a non-isocyanate polyurethane coating (NIPU-2): According to the formulation in Table 3, the above-mentioned waterborne trimethylolpropane aminopropane cyclic carbonate emulsion, 1,6-hexanediamine and defoamer were stirred evenly at room temperature and then sprayed. The ratio of primary amine to cyclic carbonate functional groups was 1.3:1, and the coating was cured at 130°C for 3 hours.

[0047] Table 3 Raw materials and their usage

[0048]

[0049] The coating properties obtained above are similar to those of Covestro Arcol Polyol 3553 polyester polyol (curing agent is Duranate manufactured by Asahi Kasei Corporation of Japan). TM Two-component polyurethane coatings prepared with HDI and Dow epoxy resin DER TM The performance comparison of 331 coatings is shown in Table 4 below:

[0050] Table 4. Coating performance test results

[0051] Testing items Two-component polyurethane <![CDATA[D.E.R TM 331]]> Example 2 Detection methods Gloss (60°) 96 97 97 GB / T 9754-2007 Pencil hardness 2H 2H 3H GB / T 6739-2006 Impact strength / cm 50 10 60 GB / T 1732-1993 Adhesion strength / grade (cross-cut test) 1 1 0 GB / T 9286-1998 Flexibility / mm 0.5 1 0.5 ISO 1519:2011

[0052] Table 4 shows that the waterborne trimethylolpropane non-isocyanate polyurethane coating of this invention has excellent gloss; compared with two-component polyurethane, this invention performs better in pencil hardness, impact strength, and adhesion; compared with epoxy resin DER TM 331 performs better in terms of pencil hardness, impact strength, adhesion, and flexibility.

[0053] Example 3

[0054] This embodiment provides a method for preparing waterborne sorbitan aminoethanesulfonic acid cyclic carbonate resin and waterborne sorbitan non-isocyanate polyurethane coating, comprising the following steps:

[0055] (1) Waterborne sorbitan aminoethanesulfonic acid cyclic carbonate resin: Sorbitol tetracyclic carbonate compound was added to a round-bottom flask, followed by 15% (by weight) of butanone (by mass) of the sorbitan tetracyclic carbonate compound, and 2-aminoethanesulfonic acid (with a molar ratio of amino to cyclic carbonate groups of 1:4). The reaction was carried out at 50°C for 1 hour. Then, N,N-dimethylcyclohexylamine (by mass of 1.1 times the mass of 2-aminoethanesulfonic acid) was added dropwise for neutralization. The reaction was carried out at 130°C for 7 hours to obtain waterborne sorbitan aminoethanesulfonic acid cyclic carbonate resin. When the temperature dropped to 80°C, water was added dropwise with rapid stirring to obtain a waterborne sorbitan aminoethanesulfonic acid cyclic carbonate emulsion. This emulsion was a brownish-brown viscous liquid with a solid content of 35%, a viscosity of 50 mPa·s, and a storage stability of more than one year.

[0056] (2) The waterborne sorbitol NIPU coating was prepared by the following steps: The waterborne sorbitol aminoethanesulfonic acid cyclic carbonate emulsion prepared in Example 3 was further used to prepare a non-isocyanate polyurethane coating (NIPU-3): According to the formulation in Table 5, the above waterborne sorbitol aminoethanesulfonic acid cyclic carbonate emulsion, 1,8-octanediamine and defoamer were stirred evenly at room temperature and then sprayed. The ratio of primary amine to cyclic carbonate functional groups was 1:1.2, and the coating was cured at 110°C for 4 hours.

[0057] Table 5 Raw materials and their usage

[0058] Serial Number composition weight fraction / % 1 1:4 Waterborne Sorbitol Aminoethanesulfonic Acid Cyclocarbonate Emulsion 80 2 1,8-Octandiamine 18.5 3 TEGO Airex 962 defoamer 1.5 4 total 100

[0059] The results of the coating performance comparison are as follows:

[0060] Table 6. Coating performance test results

[0061]

[0062] As shown in Table 6, the waterborne sorbitan non-isocyanate polyurethane coating of this invention has excellent gloss; compared with two-component polyurethane, this invention has better performance in impact strength and adhesion; compared with epoxy resin DER TM 331 exhibits better performance in impact strength, adhesion, and flexibility.

[0063] Example 4

[0064] This embodiment provides a method for preparing waterborne pentaerythritol aminobutane sulfonic acid cyclic carbonate resin and waterborne pentaerythritol non-isocyanate polyurethane coating, comprising the following steps:

[0065] (1) Preparation of waterborne pentaerythritol aminobutyric acid cyclic carbonate resin: Pentaerythritol tetracyclic carbonate compound was added to a round-bottom flask, followed by 10% (by weight) of butanone and 3-aminobutyric acid (aminobutyric acid) in a molar ratio of amine to cyclic carbonate groups of 1:5. The reaction was carried out at 50°C for 1 hour. Then, N,N-dimethylcyclohexylamine (1.4 times the mass of 3-aminobutyric acid) was added dropwise for neutralization. The reaction was carried out at 140°C for 8 hours to obtain waterborne pentaerythritol aminobutyric acid cyclic carbonate resin. When the temperature dropped to 80°C, water was added dropwise with rapid stirring to obtain an waterborne pentaerythritol aminobutyric acid cyclic carbonate emulsion. It was a brownish-brown viscous liquid with a solid content of 55%, a viscosity of 2000 mPa·s, and a storage stability of more than one year.

[0066] (2) The waterborne pentaerythritol non-isocyanate polyurethane coating was prepared by the following steps: The waterborne pentaerythritol aminobutyric acid cyclic carbonate emulsion prepared in Example 4 was further used to prepare a non-isocyanate polyurethane coating (NIPU-4): According to the formula in Table 7, the above-mentioned waterborne pentaerythritol aminobutyric acid cyclic carbonate emulsion, 1,4-butanediamine and defoamer were stirred evenly at room temperature and then sprayed. The ratio of primary amine to cyclic carbonate functional groups was 1:1.05. The coating was cured at 100°C for 5 hours.

[0067] Table 7 Raw materials and their usage

[0068] Serial Number composition weight fraction / % 1 1:5 Waterborne Pentaerythritol Aminobutyric Acid Cyclocarbonate Emulsion 85 2 1,4-Butanediamine 13 3 Defoamer BYK-R605 2 4 total 100

[0069] The coating performance results are as follows:

[0070] Table 8. Coating performance test results

[0071]

[0072] As shown in Table 8, the waterborne pentaerythritol non-isocyanate polyurethane coating of this invention has excellent gloss; compared with two-component polyurethane, this invention exhibits better performance in impact strength and adhesion; compared with epoxy resin DER... TM 331 exhibits better performance in impact strength, adhesion, and flexibility.

[0073] Example 5

[0074] This embodiment provides a method for preparing waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate resin and waterborne pentaerythritol non-isocyanate polyurethane coating, comprising the following steps:

[0075] (1) Preparation of aqueous pentaerythritol aminobenzenesulfonic acid cyclic carbonate resin: Pentaerythritol tetracyclic carbonate compound was added to a round-bottom flask, along with acetone (15% by mass of the pentaerythritol tetracyclic carbonate compound), and 3-aminobenzenesulfonic acid (the molar ratio of amino groups to cyclic carbonate groups was 1:6). The reaction temperature was 50℃, and the reaction was carried out for 0.5 h. Then, N,N-dimethylcyclohexylamine (1 times the mass of 3-aminobenzenesulfonic acid) was added dropwise for neutralization. The reaction temperature was 120℃, and the reaction was carried out for 8 h to obtain aqueous pentaerythritol aminobenzenesulfonic acid cyclic carbonate resin. When the temperature dropped to 80℃, water was added dropwise with rapid stirring to obtain an aqueous pentaerythritol aminobenzenesulfonic acid cyclic carbonate emulsion. It was a brownish-brown viscous liquid with a solid content of 45%, a viscosity of 200 mPa·s, and a storage stability of more than 1 year.

[0076] (2) The waterborne pentaerythritol non-isocyanate polyurethane coating was prepared by the following steps: The waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate emulsion prepared in Example 5 was further used to prepare a non-isocyanate polyurethane coating (NIPU-5): According to the formula in Table 9, the above waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate emulsion, diethylenetriamine, and defoamer were stirred evenly at room temperature and then sprayed. The ratio of primary amine to cyclic carbonate functional groups was 1:1.3, and the coating was cured at 100°C for 2 hours.

[0077] Table 9 Raw materials and their usage

[0078] Serial Number composition weight fraction 1 1:3 Waterborne Pentaerythritol Aminobenzenesulfonic Acid Cyclocarbonate Emulsion 80 2 Diethylenetriamine 19.5 3 TEGO Airex 962 defoamer 0.5 4 total 100

[0079] The coating performance results are as follows:

[0080] Table 10 Coating performance test results

[0081]

[0082] Table 10 shows that the waterborne pentaerythritol non-isocyanate polyurethane coating of this invention has excellent gloss; compared with two-component polyurethane, this invention has better adhesion; compared with epoxy resin DER TM 331 exhibits better performance in impact strength, adhesion, and flexibility.

[0083] Example 6

[0084] This embodiment provides a method for preparing waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate resin and waterborne pentaerythritol non-isocyanate polyurethane coating, comprising the following steps:

[0085] (1) Preparation of waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate resin: Pentaerythritol tetracyclic carbonate compound was added to a round-bottom flask, followed by acetone (5% by mass of the pentaerythritol tetracyclic carbonate compound), and 3-aminobenzenesulfonic acid (the molar ratio of amino groups to cyclic carbonate groups was 1:3). The reaction temperature was 50℃, and the reaction was carried out for 0.5 h. Then, N,N-dimethylcyclohexylamine (1.5 times the mass of 3-aminobenzenesulfonic acid) was added dropwise for neutralization. The reaction temperature was 140℃, and the reaction was carried out for 8 h to obtain waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate resin. When the temperature dropped to 80℃, water was added dropwise with rapid stirring to obtain a waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate emulsion, which was a brownish-brown viscous liquid with a solid content of 55%, a viscosity of 1500 mPa·s, and a storage stability of more than 1 year.

[0086] (2) The waterborne pentaerythritol non-isocyanate polyurethane coating was prepared by the following steps: The waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate emulsion prepared in Example 6 was further used to prepare a non-isocyanate polyurethane coating (NIPU-6): According to the formula in Table 11, the above waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate emulsion, triethylenetetramine, and defoamer were stirred evenly at room temperature and then sprayed. The ratio of primary amine to cyclic carbonate functional groups was 1:1.3, and the coating was cured at 100°C for 5 hours.

[0087] Table 11 Raw materials and their usage

[0088] Serial Number composition weight fraction 1 1:3 Waterborne Pentaerythritol Aminobenzenesulfonic Acid Cyclocarbonate Emulsion 90 2 Triethylenetetramine 9.5 3 TEGO Airex 962 defoamer 0.5 4 total 100

[0089] The coating performance results are as follows:

[0090] Table 12 Coating performance test results

[0091]

[0092] Table 12 shows that the waterborne pentaerythritol non-isocyanate polyurethane coating of this invention has excellent gloss; compared with two-component polyurethane, this invention has better performance in impact strength and adhesion; compared with epoxy resin DER TM 331 exhibits better performance in impact strength, adhesion, and flexibility.

[0093] Example 7

[0094] This embodiment provides a method for preparing waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate resin and waterborne pentaerythritol non-isocyanate polyurethane coating, comprising the following steps:

[0095] (1) Preparation of aqueous pentaerythritol aminobenzenesulfonic acid cyclic carbonate resin: Pentaerythritol tetracyclic carbonate compound was added to a round-bottom flask, and 3-aminobenzenesulfonic acid was added, wherein the molar ratio of amino groups to cyclic carbonate groups was 1:4. The reaction temperature was 50℃, and the reaction was carried out for 1 h. Then, N,N-dimethylcyclohexylamine, with a mass of 1.2 times that of 3-aminobenzenesulfonic acid, was added dropwise for neutralization. The reaction temperature was 150℃, and the reaction was carried out for 6 h to obtain aqueous pentaerythritol aminobenzenesulfonic acid cyclic carbonate resin. After the temperature dropped to 80℃, water was added dropwise with rapid stirring to obtain an aqueous pentaerythritol aminobenzenesulfonic acid cyclic carbonate emulsion.

[0096] (2) The waterborne pentaerythritol non-isocyanate polyurethane coating was prepared by the following steps: The waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate emulsion prepared in Example 7 was further used to prepare a non-isocyanate polyurethane coating (NIPU-7): According to the formulation in Table 13, the above-mentioned waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate emulsion, isophorone diamine curing agent, and defoamer were stirred evenly at room temperature and then sprayed. The ratio of primary amine to cyclic carbonate functional groups was 1:1.1, and the coating was cured at 150°C for 2 hours.

[0097] Table 13 Raw materials and their usage

[0098] Serial Number composition weight fraction 1 1:4 Waterborne Pentaerythritol Aminobenzenesulfonic Acid Cyclocarbonate Emulsion 85 2 Isophorone diamine 14 3 TEGO Airex 900 defoamer 1 4 total 100

[0099] The coating performance results are as follows:

[0100] Table 14 Coating performance test results

[0101]

[0102] As shown in Table 14, the waterborne pentaerythritol non-isocyanate polyurethane coating of this invention has excellent gloss; compared with two-component polyurethane, this invention has better performance in impact strength and adhesion; compared with epoxy resin DER TM 331 exhibits better performance in impact strength, adhesion, and flexibility.

[0103] Example 8

[0104] This embodiment provides a method for preparing waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate resin and waterborne pentaerythritol non-isocyanate polyurethane coating, comprising the following steps:

[0105] (1) Preparation of aqueous pentaerythritol aminobenzenesulfonic acid cyclic carbonate resin: Pentaerythritol tetracyclic carbonate compound was added to a round-bottom flask, and 3-aminobenzenesulfonic acid was added, wherein the molar ratio of amino groups to cyclic carbonate groups was 1:4. The reaction temperature was 50℃, and the reaction was carried out for 0.5 h. Then, N,N-dimethylcyclohexylamine, with a mass of 1.1 times that of 3-aminobenzenesulfonic acid, was added dropwise for neutralization. The reaction temperature was 140℃, and the reaction was carried out for 5 h to obtain aqueous pentaerythritol aminobenzenesulfonic acid cyclic carbonate resin. After the temperature dropped to 80℃, water was added dropwise with rapid stirring to obtain an aqueous pentaerythritol aminobenzenesulfonic acid cyclic carbonate emulsion.

[0106] (2) The waterborne pentaerythritol non-isocyanate polyurethane coating was prepared by the following steps: The waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate emulsion prepared in Example 8 was further used to prepare a non-isocyanate polyurethane coating (NIPU-8): According to the formulation in Table 15, the above-mentioned waterborne pentaerythritol aminobenzenesulfonic acid cyclic carbonate emulsion, 1,6-hexanediamine and defoamer were stirred evenly at room temperature and then sprayed. The ratio of primary amine to cyclic carbonate functional groups was 1:1.1, and the coating was cured at 100°C for 5 hours.

[0107] Table 15 Raw materials and their usage

[0108] Serial Number composition weight fraction 1 1:4 Waterborne Pentaerythritol Aminobenzenesulfonic Acid Cyclocarbonate Emulsion 90 2 1,6-Hexamethylenediamine 8.5 3 TEGO Airex 962 defoamer 1.5 4 total 100

[0109] The coating performance results are as follows:

[0110] Table 16 Coating performance test results

[0111]

[0112] As shown in Table 16, the waterborne pentaerythritol non-isocyanate polyurethane coating of this invention has excellent gloss; compared with two-component polyurethane, this invention exhibits better adhesion; compared with epoxy resin DER... TM 331 exhibits better performance in impact strength, adhesion, and flexibility.

[0113] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the embodiments described above. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a waterborne non-isocyanate polyurethane coating, characterized in that, Includes the following steps: (1) Preparation of waterborne cyclic carbonate resin: Add polycyclic carbonate to an organic solvent, then add aminosulfonic acid to react, react at 45~55℃ for 0.5~1 hours, add N,N-dimethylcyclohexylamine to neutralize, continue to react at 120~150℃ for 5~8 hours, then add water to disperse to obtain waterborne cyclic carbonate resin. (2) Preparation of waterborne non-isocyanate polyurethane coating: The waterborne cyclic carbonate resin, polyamine curing agent and defoamer prepared in step (1) are stirred evenly at 20~30℃, sprayed to form a film, and baked at 100~150℃ for 2~5h to cure, thereby obtaining non-isocyanate polyurethane coating.

2. The method for preparing the waterborne non-isocyanate polyurethane coating according to claim 1, characterized in that, The polycyclic carbonate mentioned in step (1) is at least one of trimethylolpropane tricyclic carbonate, pentaerythritol tetracyclic carbonate, and sorbitol tetracyclic carbonate.

3. The method for preparing the waterborne non-isocyanate polyurethane coating according to claim 1, characterized in that, The aminosulfonic acid mentioned in step (1) is one of 2-aminoethanesulfonic acid, 3-amino-1-propanesulfonic acid, 3-aminobutyric acid and 3-aminobenzenesulfonic acid.

4. The method for preparing the waterborne non-isocyanate polyurethane coating according to claim 3, characterized in that, The molar ratio of the amino group in the aminosulfonic acid to the carbonate group in the polycyclic carbonate in step (1) is 1:2~6.

5. The method for preparing the waterborne non-isocyanate polyurethane coating according to claim 1, characterized in that, The mass of the N,N-dimethylcyclohexylamine is 1 to 1.5 times the mass of aminosulfonic acid.

6. The method for preparing the waterborne non-isocyanate polyurethane coating according to claim 1, characterized in that, The polyamine curing agent mentioned in step (2) is one or two of 1,4-butanediamine, 1,6-hexanediamine, 1,8-octanediamine, isophoronediamine, diethylenetriamine and triethylenetetramine.

7. The method for preparing the waterborne non-isocyanate polyurethane coating according to claim 1, characterized in that, The defoamer mentioned in step (2) is at least one of BYK-R605, TEGO Airex 900, and TEGO Airex 962, with a mass fraction of 0.5% to 2% of the total mass of the raw materials.

8. The method for preparing the waterborne non-isocyanate polyurethane coating according to claim 1, characterized in that, The organic solvent mentioned in step (1) is at least one of acetone and butanone.

9. A waterborne non-isocyanate polyurethane coating, characterized in that, It is prepared by the method for preparing waterborne non-isocyanate polyurethane coatings according to any one of claims 1 to 8.

10. A method for preparing an aqueous cyclic carbonate resin, characterized in that, Includes the following steps: Polycyclic carbonates are added to an organic solvent, followed by the addition of aminosulfonic acid for reaction. After reacting at 45-55°C for 0.5-1 hour, N,N-dimethylcyclohexylamine is added for neutralization, and the reaction is continued at 120-150°C for 5-8 hours to obtain an aqueous cyclic carbonate resin. The polycyclic carbonate is at least one of trimethylolpropane tricyclic carbonate, pentaerythritol tetracyclic carbonate, and sorbitol tetracyclic carbonate; The aminosulfonic acid mentioned is one of 2-aminoethanesulfonic acid, 3-amino-1-propanesulfonic acid, 3-aminobutyric acid, and 3-aminobenzenesulfonic acid.

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