High-resistance self-extinction waterborne polyurethane resin as well as preparation method and application thereof

Abstract

The invention discloses high-resistance self-extinction waterborne polyurethane resin as well as a preparation method and application thereof, the preparation method comprises the following steps: S1, uniformly mixing polymeric polyol, a catalyst, a carboxylate hydrophilic chain extender and a micromolecule chain extender to obtain a mixed system; s2, diisocyanate is added into the mixed system in the step S1 for a reaction, and an addition product is obtained; s3, after the addition product obtained in the step S2 is cooled to the room temperature, adding an organic solvent, and then adding a neutralizer for neutralization to obtain a waterborne polyurethane prepolymer; s4, a sulfonate chain extender is added into the waterborne polyurethane prepolymer prepared in the step S3 for reaction, water is added for emulsification, and waterborne polyurethane emulsion is obtained; and S5, dispersing an amine chain extender with water, adding the dispersed amine chain extender into the waterborne polyurethane emulsion obtained in the step S4, and carrying out a reaction so as to obtain the high-resistance self-extinction waterborne polyurethane resin. According to the preparation method, function integration is realized, the production process is simplified, and the production efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane coating technology, specifically relating to a high-durability self-matting waterborne polyurethane resin, its preparation method, and its application. Background Technology

[0002] Waterborne polyurethane, with its unique microphase separation structure of soft and hard segments and excellent mechanical strength, chemical stability, low-temperature flexibility, and resilience, has found wide application in various fields such as adhesives, coatings, elastomers, foams, and fibers. In areas seeking specific functions and decorative effects, such as leather finishing, paper coating, printing pastes, textile coatings, and specialty coatings, low-gloss coatings are highly favored for their soft, natural, and elegant appearance and feel. Unfortunately, waterborne polyurethane often exhibits high gloss after film formation, requiring modification treatment to reduce its surface gloss and achieve a matte effect.

[0003] Traditional methods for modifying the matting finish of waterborne polyurethane primarily rely on the addition of external matting agents, such as microwax powders or inorganic silica, which are incorporated into the waterborne polyurethane dispersion through physical blending. After the coating dries, the matting agent particles float on the surface, forming a microscopic, uneven structure that increases surface roughness and diffuse light reflection, thus achieving a matting effect. However, this method has a significant drawback: the matting agent particles have poor compatibility with organic polyurethane, making it difficult to achieve uniform dispersion in the emulsion. This not only reduces the stability of the emulsion but may also lead to a weakening of the matting effect after prolonged storage, and even uneven gloss on the coating surface. Therefore, the application of external matting agents in the matting modification of waterborne polyurethane is severely limited.

[0004] Furthermore, even when waterborne polyurethane with a matte finish is synthesized, it still suffers from insufficient durability. The waterborne polyurethane resin molecular chain contains hydrophilic groups, making it prone to absorbing water and swelling, leading to coating softening, decreased adhesion, and even blistering and peeling. This is particularly pronounced in humid environments or applications requiring contact with water, such as wooden furniture and outdoor coatings. Additionally, it is susceptible to swelling, dissolution, or degradation when exposed to solvents such as acids and alkalis, resulting in coating failure and shortened lifespan, thus hindering the further application of self-matte waterborne polyurethane resins. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a method for preparing a high-resistance self-matting waterborne polyurethane resin. This method can prepare a self-matting waterborne polyurethane resin with water resistance and acid and alkali resistance, which achieves functional integration, simplifies the production process, and improves production efficiency.

[0006] The present invention also proposes a high-durability self-matting waterborne polyurethane resin prepared by the above preparation method.

[0007] The present invention also proposes an application.

[0008] According to a first aspect of the present invention, a method for preparing a high-durability self-matting waterborne polyurethane resin is provided, the method comprising the following steps:

[0009] S1: Mix the polymerized polyol, catalyst, carboxylate hydrophilic chain extender and small molecule chain extender evenly to obtain a mixed system;

[0010] S2: Add diisocyanate to the mixture described in step S1 to react and obtain the addition product;

[0011] S3: After the addition product obtained in step S2 has cooled to room temperature, add an organic solvent and then add a neutralizing agent to neutralize it, thus obtaining an aqueous polyurethane prepolymer.

[0012] S4: Add the sulfonate chain extender to the aqueous polyurethane prepolymer obtained in step S3 for reaction, and emulsify with water to obtain an aqueous polyurethane emulsion.

[0013] S5: Disperse the amine chain extender in water and add it to the waterborne polyurethane emulsion obtained in step S4 to react and obtain a high-durability self-matting waterborne polyurethane resin.

[0014] In some embodiments of the present invention, the polymerized polyol in step S1 includes at least one of polypropylene glycol, polycaprolactone diol, polycarbonate diol, polyhexamethylene adipate diol, polytetrahydrofuran ether diol, polyglycerol, and polyethylene glycol.

[0015] In some embodiments of the present invention, the polymeric polyol accounts for 50% to 80% of the total mass of the polymeric polyol, the carboxylate hydrophilic chain extender, the small molecule chain extender, the catalyst, and the diisocyanate.

[0016] In some embodiments of the present invention, the polymeric polyol accounts for 60% to 70% of the total mass of the polymeric polyol, the carboxylate hydrophilic chain extender, the small molecule chain extender, the catalyst, and the diisocyanate.

[0017] In some embodiments of the present invention, the molecular weight of the polymeric polyol is 600 to 8000 g / mol.

[0018] In some embodiments of the present invention, the molecular weight of the polymeric polyol is 1000 to 8000 g / mol.

[0019] In some embodiments of the present invention, the catalyst in step S1 includes an organobismuth catalyst and / or an organotin catalyst.

[0020] In some embodiments of the present invention, the organic bismuth catalyst includes at least one of bismuth neodecanoate, bismuth isooctanoate, and bismuth ethylhexanoate.

[0021] In some embodiments of the present invention, the organotin catalyst includes at least one of dibutyltin dilaurate, stannous octoate, and dibutyltin diacetate.

[0022] In some embodiments of the present invention, the mass of the catalyst accounts for 0.01% to 0.1% of the total mass of the polymeric polyol, the carboxylate hydrophilic chain extender, the small molecule chain extender, the catalyst, and the diisocyanate.

[0023] In some embodiments of the present invention, the mass of the catalyst accounts for 0.02% to 0.05% of the total mass of the polymeric polyol, the carboxylate hydrophilic chain extender, the small molecule chain extender, the catalyst, and the diisocyanate.

[0024] In some embodiments of the present invention, the carboxylate hydrophilic chain extender includes 2,2-dimethylolpropionic acid and / or 2,2-dimethylolbutyric acid.

[0025] In some embodiments of the present invention, the mass of the carboxylate hydrophilic chain extender accounts for 0.5% to 3% of the total mass of the polymeric polyol, the carboxylate hydrophilic chain extender, the small molecule chain extender, the catalyst, and the diisocyanate.

[0026] In some embodiments of the present invention, the mass of the carboxylate hydrophilic chain extender accounts for 0.5% to 2% of the total mass of the polymeric polyol, the carboxylate hydrophilic chain extender, the small molecule chain extender, the catalyst, and the diisocyanate.

[0027] In some embodiments of the present invention, the small molecule chain extender in step S1 includes at least one of 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, trimethylolpropane, glycerol, and pentaerythritol.

[0028] In some embodiments of the present invention, the mass of the small molecule chain extender accounts for 0.1% to 2% of the total mass of the polymeric polyol, the carboxylate hydrophilic chain extender, the small molecule chain extender, the catalyst, and the sulfonate chain extender.

[0029] In some embodiments of the present invention, the mass of the small molecule chain extender accounts for 0.1% to 1.5% of the total mass of the polymeric polyol, the carboxylate hydrophilic chain extender, the small molecule chain extender, the catalyst, and the sulfonate chain extender.

[0030] In some embodiments of the present invention, the diisocyanate in step S2 includes at least one of dicyclohexylmethane diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, and isophorone diisocyanate.

[0031] In some embodiments of the present invention, the molar amount of isocyanate groups in the diisocyanate is 1.6 to 2.3 times the total molar amount of hydroxyl groups in the carboxylic acid hydrophilic chain extender, small molecule chain extender, sulfonate chain extender, and polymeric polyol.

[0032] In some embodiments of the present invention, the temperature of the reaction in step S2 is 75°C to 85°C.

[0033] In some embodiments of the present invention, the reaction time in step S2 is 2 to 4 hours.

[0034] In some embodiments of the present invention, the organic solvent in step S3 includes at least one of acetone, butanone, N,N-dimethylformamide, N,N-dimethylacetamide, ethyl acetate, and methyl acetate.

[0035] In some embodiments of the present invention, the organic solvent is 40% to 60% of the mass of the aqueous polyurethane prepolymer.

[0036] In some embodiments of the present invention, the neutralizing agent in step S3 includes at least one of triethylamine, triethanolamine, diethanolamine, and potassium hydroxide.

[0037] In some embodiments of the present invention, the degree of neutralization of the neutralizing agent in step S3 is 80% to 100%.

[0038] In some embodiments of the present invention, the temperature of the reaction in step S3 is 30°C to 50°C.

[0039] In some embodiments of the present invention, the reaction time in step S3 is 20 to 40 minutes.

[0040] In some embodiments of the present invention, the sulfonate chain extender in step S4 includes at least one of sodium ethylenediaminoethanesulfonate, sodium 2-[(2-aminoethyl)amino]ethanesulfonate, and sodium 3-[(2-aminoethyl)amino]propanesulfonate.

[0041] In some embodiments of the present invention, the mass of the sulfonate chain extender accounts for 0.5% to 3% of the total mass of the polymeric polyol, the carboxylate hydrophilic chain extender, the small molecule chain extender, the catalyst, and the sulfonate chain extender.

[0042] In some embodiments of the present invention, the temperature of the reaction in step S4 is 25°C to 50°C.

[0043] In some embodiments of the present invention, the reaction time in step S4 is 15 to 30 minutes.

[0044] In some embodiments of the present invention, the amine chain extender in step S5 includes at least one of hydrazine hydrate, ethylenediamine, butanediamine, cyclohexanediamine, m-phenylenediamine, p-phenylenediamine, isophorone diamine, 1,3-cyclohexanedimethylamine, diethylenetriamine, and triethylenetetramine.

[0045] In some embodiments of the present invention, the amine chain extender is 5% to 10% of the mass of the waterborne polyurethane prepolymer.

[0046] In some embodiments of the present invention, the amount of water added in step S5 is 0.5 to 1.5 times the mass of the waterborne polyurethane prepolymer.

[0047] In some embodiments of the present invention, the temperature of the reaction in step S5 is 10°C to 30°C.

[0048] In some embodiments of the present invention, the reaction time in step S5 is 20 to 40 minutes.

[0049] According to a second aspect of the present invention, a high-durability self-matting waterborne polyurethane resin prepared by the preparation method described in the first aspect of the present invention is provided.

[0050] According to a third aspect of the present invention, the application of the preparation method described in the first aspect of the present invention in the preparation of self-matting coatings is proposed.

[0051] The present invention has at least the following beneficial effects:

[0052] The present invention has the following beneficial effects:

[0053] 1) This invention enables the prepolymer to have internal emulsification ability by introducing a carboxylate hydrophilic chain extender, and further improves the emulsification ability by adding a sulfonate chain extender first in the post-chain extension process; in addition, the phase inversion emulsification process is adopted, and there is no large viscosity peak in the emulsification process; the preparation method is simple, the conditions are easy to control, and the tolerance is good.

[0054] 2) This invention prepares high-durability self-matting waterborne polyurethane by adjusting the raw material formulation and production process of the resin. No external matting agent is required, which simplifies the production process, reduces the complexity of the process, and ensures the stability and consistency of the product gloss. It breaks through the limitations of traditional matting processes and provides new ideas and technical paths for the functional design of waterborne polyurethane.

[0055] 3) The high-resistance self-matting waterborne polyurethane resin prepared by this invention exhibits excellent water and acid / alkali resistance. This allows the self-matting resin to maintain excellent water and acid / alkali resistance while achieving a matting effect. Compared to traditional post-addition of additives to improve water and acid / alkali resistance, this method achieves functional integration, simplifies the production process, and improves production efficiency. Furthermore, the excellent water and acid / alkali resistance means that the material is less prone to swelling, hydrolysis, or degradation in humid environments or chemical media, thus significantly extending the material's service life. Attached Figure Description

[0056] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0057] Figure 1 This is a photograph of the high-durability self-matting waterborne polyurethane resin coating prepared in Example 1 of the present invention.

[0058] Figure 2 The image shows the SEM results of the high-durability self-matting waterborne polyurethane resin prepared in Example 1 of this invention, where the scale bars are 10 μm and 2 μm, respectively. Detailed Implementation

[0059] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0060] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0061] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in this technical field.

[0062] Example 1

[0063] This embodiment prepares a highly durable, self-matting waterborne polyurethane, the preparation method of which includes the following steps:

[0064] 1) Place 164.3g of polytetrahydrofuran ether glycol 1000 and 8g of polyethylene glycol 3000 under vacuum dehydration at 90℃ and a vacuum degree of -0.1MPa;

[0065] 2) Mix the dehydrated polytetrahydrofuran ether glycol 1000, polyethylene glycol 3000, 5.3g of 2,2-dimethylolpropionic acid, 1.02g of 1,2-propanediol, and 0.1g of the catalyst dibutyltin dilaurate evenly, and heat to 60℃ and stir for 5min.

[0066] 3) Add 97.6 g of isophorone diisocyanate to the reaction system of step 2) and mix well. Heat to 80°C and react for 3 h to obtain the isocyanate-terminated addition product.

[0067] 4) Cool the isocyanate-terminated addition product obtained in step 3) to 50°C, add 150g of acetone to reduce viscosity, add 4.0g of neutralizing agent triethylamine at 40°C, react for 30min to obtain waterborne polyurethane prepolymer.

[0068] 5) Add 2.2g of sodium ethylenediamine ethanesulfonate to the waterborne polyurethane prepolymer obtained in step 4), react at 40℃ for 20min, cool down and add 437g of deionized water for reverse emulsification to obtain waterborne polyurethane emulsion.

[0069] 6) Disperse 33.3g of isophorone diamine in 291g of deionized water and cool it to below 20℃. Add it dropwise to the aqueous polyurethane emulsion prepared in step 5) for post-chain extension. The disperser speed is 750r / min and the mixture is stirred for 30min.

[0070] 7) The waterborne resin obtained by post-chain extension in step 6) is vacuumed at 40°C using a vacuum pump to remove acetone, thereby obtaining a high-durability self-matting waterborne polyurethane resin.

[0071] The actual image of the high-durability self-matting waterborne polyurethane resin coating prepared in this embodiment is shown below. Figure 1 As shown.

[0072] The SEM observation results of the high-durability self-matting waterborne polyurethane prepared in this embodiment are as follows: Figure 2 As shown.

[0073] Depend on Figure 1 and Figure 2 It can be seen that the surface of the polyurethane resin coating exhibits annular and spherical micromorphology, and the large surface roughness is conducive to diffuse reflection of light and achieves a good matting effect.

[0074] Example 2

[0075] This embodiment prepares a highly durable, self-matting waterborne polyurethane, the preparation method of which includes the following steps:

[0076] 1) Place 164.3g of polytetrahydrofuran ether glycol 1000 and 8g of polyethylene glycol 3000 under vacuum dehydration at 90℃ and a vacuum degree of -0.1MPa;

[0077] 2) Mix the dehydrated polytetrahydrofuran ether glycol 1000, polyethylene glycol 3000, 5.3g of 2,2-dimethylolpropionic acid, 1.02g of 1,2-propanediol, and 0.1g of the catalyst dibutyltin dilaurate evenly, and heat to 60℃ and stir for 5min.

[0078] 3) Add 99.6 g of isophorone diisocyanate to the reaction system of step 2) and mix well. Heat to 80°C and react for 3 h to obtain the isocyanate-terminated addition product.

[0079] 4) Cool the isocyanate-terminated addition product obtained in step 3) to 50°C, add 150g of acetone to reduce viscosity, add 4.0g of neutralizing agent triethylamine at 40°C, react for 30min to obtain waterborne polyurethane prepolymer.

[0080] 5) Add 2.2g of sodium ethylenediamine ethanesulfonate to the waterborne polyurethane prepolymer prepared in step 4), react at 40℃ for 20min, cool down and add 437g of deionized water for reverse emulsification to obtain waterborne polyurethane emulsion.

[0081] 6) Disperse 33.3g of isophorone diamine in 291g of deionized water and cool it to below 20℃. Add it dropwise to the aqueous polyurethane emulsion prepared in step 5) for post-chain extension. The disperser speed is 750r / min and the mixture is stirred for 30min.

[0082] 7) The waterborne resin obtained by post-chain extension in step 6) is vacuumed at 40°C using a vacuum pump to remove acetone, thereby obtaining a high-durability self-matting waterborne polyurethane resin.

[0083] Example 3

[0084] This embodiment prepares a highly durable, self-matting waterborne polyurethane, the preparation method of which includes the following steps:

[0085] 1) Place 164.3g of polytetrahydrofuran ether glycol 1000 and 8g of polyethylene glycol 3000 under vacuum dehydration at 90℃ and a vacuum degree of -0.1MPa;

[0086] 2) Mix the dehydrated polytetrahydrofuran ether glycol 1000, polyethylene glycol 3000, 5.3g of 2,2-dimethylolpropionic acid, 1.02g of 1,2-propanediol, and 0.1g of the catalyst dibutyltin dilaurate evenly, and heat to 60℃ and stir for 5min.

[0087] 3) Add 97.6 g of isophorone diisocyanate to the reaction system of step 2) and mix well. Heat to 80°C and react for 3 h to obtain the isocyanate-terminated addition product.

[0088] 4) Cool the isocyanate-terminated addition product obtained in step 3) to 50°C, add 150g of acetone to reduce viscosity, add 4.0g of neutralizing agent triethylamine at 40°C, react for 30min to obtain waterborne polyurethane prepolymer.

[0089] 5) Add 4.2g of sodium ethylenediamine ethanesulfonate to the waterborne polyurethane prepolymer prepared in step 4), react at 40℃ for 20min, cool down and add 437g of deionized water for reverse emulsification to obtain waterborne polyurethane emulsion.

[0090] 6) Disperse 33.3g of isophorone diamine in 291g of deionized water and cool it to below 20℃. Add it dropwise to the aqueous polyurethane emulsion prepared in step 5) for post-chain extension. The disperser speed is 750r / min and the mixture is stirred for 30min.

[0091] 7) The waterborne resin obtained by post-chain extension in step 6) is vacuumed at 40°C using a vacuum pump to remove acetone, thereby obtaining a high-durability self-matting waterborne polyurethane resin.

[0092] Example 4

[0093] This embodiment prepares a highly durable, self-matting waterborne polyurethane, the preparation method of which includes the following steps:

[0094] 1) Place 164.3g of polytetrahydrofuran ether glycol 1000 and 10g of polyethylene glycol 8000 under vacuum dehydration at 90℃ and a vacuum degree of -0.1MPa;

[0095] 2) Mix the dehydrated polytetrahydrofuran ether glycol 1000, polyethylene glycol 8000, 5.1g of 2,2-dimethylolpropionic acid, 1.2g of 1,4-butanediol, and 0.1g of the catalyst dibutyltin dilaurate evenly, and heat to 60℃ and stir for 5min.

[0096] 3) Add 101.5g of isophorone diisocyanate to the reaction system of step 2) and mix well. Heat to 80℃ and react for 3h to obtain the isocyanate-terminated addition product.

[0097] 4) Cool the isocyanate-terminated addition product obtained in step 3) to 50°C, add 150g of acetone to reduce viscosity, add 3.9g of neutralizing agent triethylamine at 40°C, react for 30min to obtain waterborne polyurethane prepolymer.

[0098] 5) Add 2.3g of sodium ethylenediamine ethanesulfonate to the waterborne polyurethane prepolymer prepared in step 4), react at 40℃ for 20min, cool down and add 448g of deionized water for reverse emulsification to obtain waterborne polyurethane emulsion.

[0099] 6) Disperse 33g of 1,3-cyclohexanedimethylamine in 299g of deionized water, cool it to below 20℃, and add it dropwise to the aqueous polyurethane emulsion prepared in step 5) for post-chain extension. The disperser speed is 750r / min, and the mixture is stirred for 30min.

[0100] 7) The waterborne resin obtained by post-chain extension in step 6) is vacuumed at 40°C using a vacuum pump to remove acetone, thereby obtaining a high-durability self-matting waterborne polyurethane resin.

[0101] Example 5

[0102] This embodiment prepares a highly durable, self-matting waterborne polyurethane, the preparation method of which includes the following steps:

[0103] 1) Place 164.3g of polypropylene glycol 1000 and 10g of polyethylene glycol 3000 under vacuum dehydration conditions of 90℃ and -0.1MPa;

[0104] 2) Mix the dehydrated polypropylene glycol 1000 and polyethylene glycol 3000 from step 1) with 5.3g of 2,2-dimethylolpropionic acid, 1.02g of 1,2-propanediol and 0.1g of the catalyst dibutyltin dilaurate evenly, and heat to 60℃ and stir for 5min.

[0105] 3) Add 97.6 g of isophorone diisocyanate to the reaction system of step 2) and mix well. Heat to 80°C and react for 3 h to obtain the isocyanate-terminated addition product.

[0106] 4) Cool the isocyanate-terminated addition product obtained in step 3) to 50°C, add 150g of acetone to reduce viscosity, add 4.0g of neutralizing agent triethylamine at 40°C, react for 30min to obtain waterborne polyurethane prepolymer.

[0107] 5) Add 2.2g of sodium ethylenediamine ethanesulfonate to the waterborne polyurethane prepolymer prepared in step 4), react at 40℃ for 20min, cool down and add 437g of deionized water for reverse emulsification to obtain waterborne polyurethane emulsion.

[0108] 6) Disperse 33.3g of isophorone diamine in 291g of deionized water and cool it to below 20℃. Add it dropwise to the aqueous polyurethane emulsion prepared in step 5) for post-chain extension. The disperser speed is 750r / min and the mixture is stirred for 30min.

[0109] 7) The waterborne resin obtained by post-chain extension in step 6) is vacuumed at 40°C using a vacuum pump to remove acetone, thereby obtaining a high-durability self-matting waterborne polyurethane resin.

[0110] Comparative Example 1

[0111] This comparative example prepared an aqueous polyurethane. The only difference between this preparation method and that of Example 1 is that the amount of 2,2-dimethylolpropionic acid in step 2) was adjusted to 5.8 g, while the rest of the steps were the same as those in Example 1.

[0112] Comparative Example 2

[0113] This comparative example prepared an aqueous polyurethane. The only difference between this preparation method and that of Example 1 is that the speed of the disperser in step 6) is adjusted to 1200 r / min. All other steps are the same as those in Example 1.

[0114] Comparative Example 3

[0115] This comparative example prepared an aqueous polyurethane, the only difference between which was the preparation method and that of Example 1: the sodium ethylenediamine ethanesulfonate in step 5) was adjusted to be added in step 2), and mixed with polytetrahydrofuran ether glycol 1000, polyethylene glycol 3000, 2,2-dimethylolpropionic acid, 1,2-propanediol and the catalyst dibutyltin dilaurate for a homogeneous reaction, and step 5) was omitted, while the remaining steps were consistent with those of Example 1.

[0116] Comparative Example 4

[0117] This comparative example prepared an aqueous polyurethane, the only difference between which was the preparation method and that of Example 1: the sodium ethylenediamine ethanesulfonate in step 5) was replaced with an equimolar amount of 3.8 g of α,ω-polypropylene glycol-diamine-sulfopropyl sodium salt, and the rest of the steps were the same as in Example 1.

[0118] Comparative Example 5

[0119] This comparative example prepared an aqueous polyurethane, the only difference between which preparation method and Example 1 is that polyethylene glycol 3000 in step 1) is replaced with an equal mass of polyethylene glycol 2000.

[0120] Test example

[0121] This experiment tested various properties of the waterborne polyurethane resins prepared in Examples 1-5 and Comparative Examples 1-5. The test methods and results are as follows:

[0122] The gloss of the samples was tested according to the standard DIN EN ISO 2813-1999. A gloss meter was used to test three different areas of the sample, and the average value was calculated as the final result.

[0123] The particle size of the emulsion sample diluted 100 times was measured using a Nanotracwave II nanoparticle size analyzer.

[0124] The waterborne polyurethane resins prepared in Examples 1-6 and Examples 1-4 were coated on a test plate, dried into a film, and then subjected to a water resistance test. The method was as follows: the single-component coating obtained by the waterborne polyurethane resin film was baked at 55°C for 16 hours, and then paper was placed on the test area, water was dripped on it, and the paper was kept moist for 24 hours. After the water was absorbed, the water resistance score was observed and recorded, and it was divided into 1 to 5 points. The less whitening, the higher the score.

[0125] The chemical resistance test is the same as the water resistance test, except that the wetting time is kept for 1 hour and the water is replaced with acid or alkali.

[0126] Sulfonate chain extenders contain a small amount of water, which may form partial gel during the synthesis process, thus affecting the final filtration of waterborne polyurethane and accelerating its stratification. Therefore, it is necessary to observe the gelation process.

[0127] The results obtained from the above experiments are shown in Table 1.

[0128] Table 1 Performance Test Results

[0129]

[0130] As shown in Table 1:

[0131] 1) The self-matting waterborne polyurethanes in Examples 1 to 5 all have a certain matting effect without the addition of any matting medium. Among them, the gloss of Examples 1 and 2 is the lowest at 1.0, and they have excellent water resistance and good chemical resistance. It can be seen that the changes in gloss and hydrophilicity are affected by a variety of factors such as the amount of hydrophilic group, rotation speed and the type of chain extender.

[0132] 2) Compared with Example 1, Comparative Example 1 increased the amount of 2,2-dimethylolpropionic acid (DMPA), which resulted in a significant increase in the 60° gloss, a significant decrease in particle size, and a decrease in water resistance of the waterborne polyurethane resin prepared in Comparative Example 1. This is because the increased amount of DMPA enhanced the hydrophilicity, making the prepolymer easier to disperse in water, forming smaller latex particles after emulsification, and leading to increased gloss. At the same time, the increased hydrophilicity reduced its water resistance.

[0133] 3) Compared with Example 1, Comparative Example 2 increased the rotation speed, which resulted in a significant increase in the gloss and a significant reduction in the particle size of the waterborne polyurethane resin prepared in Comparative Example 1. The shearing effect was enhanced, thereby reducing the size of the latex particles.

[0134] 4) Compared with Example 1, Comparative Example 3 added sodium ethylenediamine ethanesulfonate earlier, which resulted in a slight increase in the gloss of the waterborne polyurethane resin prepared in Comparative Example 1, a slight decrease in particle size, and the formation of more gel. This is because sodium ethylenediamine ethanesulfonate promoted the dispersion of the prepolymer and formed smaller latex particles. At the same time, since the sulfonate contains water, its early addition caused NCO to form more gel with water.

[0135] 5) In Comparative Example 4, the type of sulfonate chain extender was changed compared to Example 1, resulting in the formation of more gel. This may be because the long-chain structure is more likely to produce steric hindrance in the reaction, which reduces the reaction rate with NCO. In contrast, the reaction between NCO and water is more pronounced, leading to an increase in the amount of gel.

[0136] 6) Compared with Example 1, Comparative Example 5 changed the molecular weight and amount of polyethylene glycol, resulting in a significant increase in the 60° gloss, a significant decrease in particle size, and a decrease in water resistance of the waterborne polyurethane resin prepared in Example 6. This is because the decrease in PEG molecular weight or the increase in amount will increase hydrophilicity, making the prepolymer easier to emulsify and form smaller latex particles. The gloss of the small particle size dispersion system is changed, the surface is smoother after film formation, and the specular reflection is enhanced.

[0137] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for preparing a high-durability self-matting waterborne polyurethane resin, characterized in that, The preparation method includes the following steps: S1: Mix the polymerized polyol, catalyst, carboxylate hydrophilic chain extender and small molecule chain extender evenly to obtain a mixed system; S2: Add diisocyanate to the mixture described in step S1 to react and obtain the addition product; S3: After the addition product obtained in step S2 has cooled to room temperature, add an organic solvent and then add a neutralizing agent to neutralize it, thus obtaining an aqueous polyurethane prepolymer. S4: Add the sulfonate chain extender to the aqueous polyurethane prepolymer obtained in step S3 for reaction, and emulsify with water to obtain an aqueous polyurethane emulsion. S5: Disperse the amine chain extender in water and add it to the waterborne polyurethane emulsion obtained in step S4 to react and obtain a high-durability self-matting waterborne polyurethane resin.

2. The preparation method according to claim 1, characterized in that, The polymerized polyols mentioned in step S1 include at least one of polypropylene glycol, polycaprolactone glycol, polycarbonate glycol, polyhexyl adipate glycol, polytetrahydrofuran ether glycol, polyglycerol, and polyethylene glycol. Preferably, the polymeric polyol accounts for 50% to 80% of the total mass of the polymeric polyol, the carboxylate hydrophilic chain extender, the small molecule chain extender, the catalyst, and the diisocyanate; Preferably, the molecular weight of the polymeric polyol is 600-8000 g / mol.

3. The preparation method according to claim 1, characterized in that, The catalyst mentioned in step S1 includes an organobismuth catalyst and / or an organotin catalyst; Preferably, the mass of the catalyst accounts for 0.01% to 0.1% of the total mass of the polymerized polyol, the carboxylate hydrophilic chain extender, the small molecule chain extender, the catalyst, and the diisocyanate; Preferably, the carboxylate hydrophilic chain extender comprises 2,2-dimethylolpropionic acid and / or 2,2-dimethylolbutyric acid; Preferably, the mass of the carboxylate hydrophilic chain extender accounts for 0.5% to 3% of the total mass of the polymeric polyol, the carboxylate hydrophilic chain extender, the small molecule chain extender, the catalyst, and the diisocyanate.

4. The preparation method according to claim 1, characterized in that, The small molecule chain extender mentioned in step S1 includes at least one of 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, trimethylolpropane, glycerol, and pentaerythritol. Preferably, the mass of the small molecule chain extender accounts for 0.1% to 2% of the total mass of the polymeric polyol, the carboxylate hydrophilic chain extender, the small molecule chain extender, the catalyst, and the sulfonate chain extender.

5. The preparation method according to claim 1, characterized in that, The diisocyanate mentioned in step S2 includes at least one of dicyclohexylmethane diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, and isophorone diisocyanate; Preferably, the molar amount of isocyanate groups in the diisocyanate is 1.6 to 2.3 times the total molar amount of hydroxyl groups in the carboxylic acid hydrophilic chain extender, small molecule chain extender, sulfonate chain extender, and polymeric polyol; Preferably, the reaction temperature in step S2 is 75°C to 85°C; Preferably, the reaction time in step S2 is 2 to 4 hours.

6. The preparation method according to claim 1, characterized in that The organic solvent mentioned in step S3 includes at least one of acetone, butanone, N,N-dimethylformamide, N,N-dimethylacetamide, ethyl acetate, and methyl acetate; Preferably, the mass of the organic solvent is 40% to 60% of the mass of the waterborne polyurethane prepolymer; Preferably, the neutralizing agent in step S3 includes at least one of triethylamine, triethanolamine, diethanolamine, and potassium hydroxide; Preferably, the neutralizing agent in step S3 has a neutralization degree of 80% to 100%; Preferably, the reaction temperature in step S3 is 30°C to 50°C; Preferably, the reaction time in step S3 is 20 to 40 minutes.

7. The preparation method according to claim 1, characterized in that, The sulfonate chain extender mentioned in step S4 includes at least one of sodium ethylenediaminoethanesulfonate, sodium 2-[(2-aminoethyl)amino]ethanesulfonate, and sodium 3-[(2-aminoethyl)amino]propanesulfonate. Preferably, the sulfonate chain extender accounts for 0.5% to 3% of the total mass of the polymeric polyol, the carboxylate hydrophilic chain extender, the small molecule chain extender, the catalyst, and the sulfonate chain extender. Preferably, the reaction temperature in step S4 is 25°C to 50°C; Preferably, the reaction time in step S4 is 15 to 30 minutes.

8. The preparation method according to claim 8, characterized in that, The amine chain extender mentioned in step S5 includes at least one of hydrazine hydrate, ethylenediamine, butanediamine, cyclohexanediamine, m-phenylenediamine, p-phenylenediamine, isophorone diamine, 1,3-cyclohexanedimethylamine, diethylenetriamine, and triethylenetetramine. Preferably, the amine chain extender is 5% to 10% of the mass of the waterborne polyurethane prepolymer; preferably, the amount of water added in step S5 is 0.5 to 1.5 times the mass of the waterborne polyurethane prepolymer. Preferably, the reaction temperature in step S5 is 10°C to 30°C; Preferably, the reaction time in step S5 is 20 to 40 minutes.

9. The high-durability self-matting waterborne polyurethane resin prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the preparation method according to any one of claims 1 to 8 in the preparation of a self-matting coating.

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