Synthesis and application of an aqueous polyurethane composition

Abstract

The application discloses synthesis and application of a water-based polyurethane composition. The preparation method comprises the following steps: synthesizing an isocyanate-terminated prepolymer; adding a diluent into the prepolymer, and dispersing to obtain a water-based polyurethane coarse emulsion after neutralization reaction; adding an amino chain extender into the water-based polyurethane coarse emulsion to obtain a water-based polyurethane coarse emulsion, and removing low-boiling-point solvents to obtain the water-based polyurethane composition. The preparation method can effectively reduce the content of low precipitates in the composition and obtain a water-based polyurethane composition with low color number. The composition can be applied to the field of industrial coatings and plastic paints.

Description

Technical Field

[0001] This invention belongs to the field of water-based industrial coatings and plastic paints, specifically relating to the synthesis and application of a water-based polyurethane composition. Background Technology

[0002] With global economic development and rising living standards, the demand for plastic coatings is continuously increasing. In recent years, the plastic coatings industry has shown a steady growth trend, with its market size expanding steadily. Plastic coatings are an important branch of the coatings industry, widely used in construction, furniture, automobiles, and home appliances.

[0003] With increasing environmental awareness and continuous technological advancements, the plastic coatings industry has gradually risen in status within the coatings industry, significantly impacting its overall development. Specifically, the automotive industry's demand for plastic coatings for automotive interiors and exteriors continues to grow alongside the development of the automotive industry. The booming home decoration market has driven demand for plastic coatings on furniture, doors, and windows. The electronics industry's demand for coating electronic product casings and internal components is constantly expanding. Other industries, such as toys and sporting goods, are also seeing increasing demand for plastic coatings year by year.

[0004] With increasingly stringent environmental protection requirements and the emergence of new coating technologies, traditional plastic paint companies are facing pressure to upgrade their technology. Environmentally friendly plastic paints with non-toxic and low VOC emissions are becoming an industry trend. This trend towards environmental protection is driving companies to increase R&D investment, promoting innovation and application of plastic paint technology.

[0005] Simultaneously, with the rapid development of the petrochemical industry, various industrial products, electronic products, daily necessities, toys, and other products based on different plastics have enriched our lives. These products cover various fields including home decoration, automotive accessories, motorcycles, home appliances, computers, electric vehicles, vacuum cleaners, mobile phones, televisions, power tools, and toys. Their substrates encompass a wide range of plastic base materials, including ABS, AS, PS, IPS, PP, PC, PE, PET, PVC, TPR, and more. These diverse and complex substrates pose significant challenges to the performance of plastic coatings. Developing a green and environmentally friendly water-based plastic coating that meets the performance requirements of different plastic base materials has become a pressing problem for the industry.

[0006] Existing technologies have disclosed methods for synthesizing polyurethane aqueous dispersions by adding N-(alkylC4)pyrrolidone instead of N-methylpyrrolidone. However, the inventors have found in practice that the prepolymer prepared by this method will yellow, and the dispersion prepared by this method has obvious limitations for applications that require yellowing. In addition, N-(alkylC4)pyrrolidone also leads to uncontrollable reaction rate and high weight-average molecular weight during the preparation process, resulting in the formation of precipitates during the later stages of dispersion preparation. How to reduce the content of precipitates is also one of the problems that urgently need to be solved in the field of waterborne polyurethane.

[0007] In summary, the aforementioned problems still exist in the current methods for introducing N-(alkylC4)pyrrolidone and urgently need to be addressed. Summary of the Invention

[0008] One of the objectives of this invention is to provide a method for preparing a waterborne polyurethane composition, which can effectively reduce the content of precipitates in the composition and obtain a waterborne polyurethane composition with a low color number.

[0009] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0010] A method for preparing an aqueous polyurethane composition, the method comprising the following steps:

[0011] S1: Synthetic isocyanate-terminated prepolymer;

[0012] S2: After adding a diluent to the prepolymer and reacting it with a neutralization reaction, an aqueous polyurethane crude emulsion is obtained by dispersion;

[0013] S3: Add an amino chain extender to the waterborne polyurethane crude emulsion to obtain the waterborne polyurethane crude emulsion, remove the low-boiling-point solvent, and obtain the waterborne polyurethane composition.

[0014] The aforementioned prior art has disclosed the addition of N-(alkyl C4)pyrrolidone, but this introduces issues related to precipitation and color. The inventors surprisingly discovered in their research that by adding NBP late in the prepolymerization process, they avoided the problem of uncontrollable reaction rates caused by NBP during prepolymerization, which resulted in excessively high weight-average molecular weights and ultimately led to slag formation during product preparation, failing to meet application requirements. Reducing or even eliminating the amount of precipitation in the composition is also a key focus of the industry. Furthermore, surprisingly, adding NBP at low temperatures during the later stages of isocyanate-terminated prepolymer preparation significantly reduced yellowing of the prepolymer. The resulting waterborne polyurethane composition better meets the application needs of high-end white paint and plastic coatings where yellowing is a critical concern.

[0015] In one embodiment of the present invention, the isocyanate-terminated prepolymer in S1 is prepared by reacting raw materials comprising the following components: polyisocyanate, macromolecular polyol, small molecule polyol, hydrophilic chain extender, monohydric alcohol and / or dihydric alcohol containing polyethylene oxide segments in the main chain and / or side chain; preferably, the amount of polyisocyanate is 32-42 wt% of the isocyanate-terminated prepolymer; preferably, the amount of macromolecular polyol is 47-62 wt% of the isocyanate-terminated prepolymer. 0.5%; preferably, the amount of the small molecule polyol is 0-6 wt% of the isocyanate-terminated prepolymer; preferably, the amount of the hydrophilic chain extender is 4-5 wt% of the isocyanate-terminated prepolymer; preferably, the amount of the monohydric alcohol and / or dihydric alcohol containing polyethylene oxide segments in the main chain and / or side chain is 0.5-1.2 wt% of the isocyanate-terminated prepolymer; preferably, the amount of the low-boiling-point solvent is 0.8-1.5 times the isocyanate-terminated prepolymer.

[0016] In one embodiment of the present invention, the polyisocyanate S1 is one or more of aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates, preferably one or more of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, pentane diisocyanate, hexahydrotoluene diisocyanate, trimethylhexane diisocyanate, phenylene diisocyanate, 1,4-cyclohexane diisocyanate, dodecyl diisocyanate, 1,5-naphthalene diisocyanate, and dicyclohexylmethane diisocyanate, more preferably dicyclohexylmethane diisocyanate and / or isophorone diisocyanate.

[0017] In one embodiment of the present invention, the macromolecular polyol in S1 is one or more of an alcohol ether ester compound containing at least two active hydrogens that can react with isocyanate groups, preferably one or more of polyethylene glycol, polypropylene glycol, polyethylene glycol-propylene glycol, polytetrahydrofuran ether diol, dimer acid polyester polyol, polyolefin polyol, polycaprolactone diol, polycarbonate diol, polyethylene adipate diol, 1,4-butanediol adipate diol, neopentyl adipate diol, 1,6-hexanediol adipate diol, and phthalic anhydride polyester polyol, more preferably polycarbonate diol; preferably, the number average molecular weight of the macromolecular polyol is 500-3000, more preferably 800-2000.

[0018] In one embodiment of the present invention, the small molecule polyol in S1 is a polyfunctional compound with a molecular weight of less than 500 g / mol containing a group that can react with isocyanate, preferably one or more of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 3-methylpentane-1,5-pentanediol, 1,6-hexanediol, neopentanediol, 1,4-cyclohexyldiethanol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 2-ethyl-3-propylpentanediol, 2,2-dimethylpentanediol, diethylene glycol, glycerol, and trimethylolpropane, more preferably 1,4-cyclohexanediethanol.

[0019] In one embodiment of the present invention, the hydrophilic chain extender S1 is an active hydrogen chain extender containing ionic groups or potential ionic groups that can react with isocyanates, preferably one or more of dimethylolpropionic acid, dimethylolbutyric acid, amino acids, aminosulfonates, tartaric acid, N,N-dimethylolmaleamic acid, diaminobenzoic acid, and sodium dihydroxypropanesulfonate, more preferably dimethylolpropionic acid.

[0020] In one embodiment of the present invention, the monohydric alcohol and / or dihydric alcohol containing polyethylene oxide segments in the main chain and / or side chain of S1 are polymer units containing polyethylene oxide segments containing 90-100 wt% ethylene oxide, preferably from Tego Chemie. D-3403, Perstrop's Ymer TM One or more of N120 and MPEG1200 from Lotte Company of South Korea, more preferably MPEG1200 from Lotte Company of South Korea.

[0021] In one embodiment of the present invention, the low-boiling solvent in S1 is an organic solvent with a boiling point below 100°C, preferably one or more of acetone, methyl ethyl ketone, cyclohexane, dichloromethane, dichloroethane, trichloroethane, ethyl acetate, pentane, heptane, and hexane, more preferably acetone.

[0022] In one embodiment of the present invention, the reaction temperature in S1 is 60-90°C.

[0023] In one embodiment of the present invention, the diluent in S2 is a compound containing a pyrrolidone structure with at least four or more alkyl carbon chains at the N-position, preferably N-butylpyrrolidone; its structure is as follows:

[0024]

[0025] Preferably, the amount of diluent used is 18-52 wt% of the isocyanate-terminated prepolymer.

[0026] In one embodiment of the present invention, the neutralizing agent in S2 is an organic or inorganic compound with neutralizing function, preferably one or more of sodium hydroxide, potassium hydroxide, triethylamine, N,N-dimethylethanolamine, dimethylcyclohexylamine, triethanolamine, methyldiethanolamine, diisopropanolamine, ethyldiisopropylamine, diisopropylcyclohexylamine, N-methylmorpholine, 2-amino-2-methyl-1-propanol, and ammonia water, more preferably triethylamine; preferably, the amount of neutralizing agent is 3-3.5 wt% of the isocyanate-terminated prepolymer.

[0027] In one embodiment of the present invention, the neutralization temperature in S2 is 35-45°C.

[0028] In one embodiment of the present invention, the amino chain extender in S3 is a polyamine containing at least two active hydrogen atoms that can react with isocyanates, preferably one or more of ethylenediamine, dicyclohexylmethanediamine, hydroxyethylethylenediamine, aminosiloxane, diethylenetriamine, triethylenetetramine, hexamethylenediamine, pentamethylenediamine, diethylenetriamine, isophoronediamine, and 4,4-diphenylmethanediamine, more preferably isophoronediamine; preferably, the amount of the amino chain extender is 3-4 wt% of the isocyanate-terminated prepolymer.

[0029] In one embodiment of the present invention, the method for removing the low-boiling-point solvent in S3 is vacuum distillation; preferably, the temperature of vacuum distillation is 40-60°C.

[0030] Another object of the present invention is to provide an aqueous polyurethane composition.

[0031] A waterborne polyurethane composition, the composition being prepared by the above-described preparation method, wherein the waterborne polyurethane composition contains a diluent added after prepolymerization; preferably, the diluent is a compound containing a pyrrolidone structure with at least four alkyl carbon chains at the N-position substituent, preferably N-butylpyrrolidone.

[0032] Another object of the present invention is to provide a use of an aqueous polyurethane composition.

[0033] Use of an aqueous polyurethane composition, wherein the composition is prepared by the above-described preparation method, or is the composition described above, wherein the composition is used in the field of industrial coatings and plastic paints.

[0034] The beneficial effects of this invention are mainly reflected in the following aspects:

[0035] (1) The waterborne polyurethane composition of the present invention can achieve better reduction of the formation of precipitates and white paint effect.

[0036] (2) The waterborne polyurethane composition containing a special diluent provided by the present invention has excellent adhesion to plastic substrates, especially amphoteric plastic substrates, and solves the problem of poor adhesion in the application of plastic paint.

[0037] (3) The waterborne polyurethane composition provided by the present invention has a simple and efficient synthesis process, has high practical application value, and is suitable for widespread promotion in the field of industrial paints and coatings and plastic paints. Detailed Implementation

[0038] To better understand the technical solution of the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0039] Unless otherwise specified, "%" in the examples or comparative examples refers to "wt%".

[0040] The test methods used in the embodiments or comparative examples are described below:

[0041] Sediment content test: Weigh a 100-mesh filter screen with an area of ​​10cm*10cm, filter 100g of the composition dispersion through the filter screen, rinse the residual composition dispersion with deionized water, place the filter screen in a 150℃ oven for 20 minutes after rinsing, and test the content of the composition residue using a differential osmosis test.

[0042] Yellowing performance test: The waterborne polyurethane emulsion to be tested was poured onto a film-forming plate and dried at 50℃ for 8 hours, and then dried at 80℃ for another 4 hours. The yellowing grade was evaluated according to the national standard GB / T 1766-1995. Visual yellowing results: When visually observed as "no color change", the corresponding color difference value is ≤1.5; when visually observed as "very slight color change", the corresponding color difference value ranges from 1.6 to 3.0; when visually observed as "slight color change", the corresponding color difference value ranges from 3.1 to 6.0; when visually observed as "obvious color change", the corresponding color difference value ranges from 6.1 to 9.0.

[0043] Particle size testing method: The particle size and particle size distribution of the polyurethane dispersion were measured using dynamic light scattering (DLS). In the experiment, a Malvern Zetasizer Nano ZS90 particle size analyzer was used to determine the particle size and particle size distribution of the emulsion. The test temperature was 25℃, the laser angle was 90°, and the test laser wavelength was 633nm.

[0044] pH testing method: Mettler pH meter was used.

[0045] Viscosity testing method: The BROOKFIELD viscometer was used, with rotor No. 3 at 30 rpm.

[0046] Adhesion test: Waterborne polyurethane emulsion was poured onto the PC board, coated with a 10μm wire rod, and then baked in a 120℃ oven for 3 minutes. The adhesion test was conducted using the cross-cut adhesion test. The adhesion grade was rated from 0 to 5 according to the national standard GB / T 9286-1998, with 5 being the worst.

[0047] Water boiling resistance test: Waterborne polyurethane emulsion is poured onto the PC board, coated with a 10μm wire rod, and then baked in a 120℃ oven for 3 minutes. Then, the PC board is boiled in a 65℃ water bath for 1 hour. After drying, the adhesion grade is rated from 0 to 5 according to the national standard GB / T9286-1998, with grade 5 being the worst.

[0048] Anti-bite performance: A 10μm water-based polyurethane film was applied to the PC board after UV primer curing and baked in a 120℃ oven for 3 minutes. The change in gloss before and after application was tested. The smaller the change in gloss, the better the performance (<0.3° is the best).

[0049] Products used in the examples:

[0050] HMDI (dicyclohexylmethane diisocyanate, NCO content 32.0%, Wanhua Chemical Group Co., Ltd.);

[0051] IPDI (Isophorone diisocyanate, NCO content 37.8%, Bayer, Germany);

[0052] UM90 (polycarbonate diol, number average molecular weight = 900, functionality 2, Ube, Japan);

[0053] PNA1000 (Polypentyl adipate diol, number average molecular weight = 1000, functionality = 2, Wanhua Chemical)

[0054] Ymer TM N120 (number-average molecular weight = 1000, functionality = 2, Postotype)

[0055] MPEG1200 (number-average molecular weight = 1200, functionality = 1, Lotte Chemicals, South Korea);

[0056] NPG (neopentyl glycol, Wanhua Chemical Group Co., Ltd.);

[0057] CHDM (1,4-cyclohexanediethanol, BASF, Germany);

[0058] Hydroxyethyl ethylenediamine (BASF, Germany);

[0059] IPDA (Isophorone Diamine, Bayer, Germany);

[0060] DMBA (dimethylolbutyric acid, Persto);

[0061] DMPA (dimethylolpropionic acid, Persto);

[0062] NBP (N-Butylpyrrolidone, Machi Chemical)

[0063] NMP (N-methylpyrrolidone, Machi Chemical)

[0064] NEP (N-ethylpyrrolidone, Machi Chemical)

[0065] TEA (triethylamine, BASF, Germany);

[0066] BiCat8108 (Bismuth neodecanoate, a leading product in the US)

[0067] Acetone (refined by Wanhua Chemical Group Co., Ltd.)

[0068] Example 1

[0069] Add 56g to a four-necked flask equipped with a reflux condenser, thermometer, and mechanical stirrer. The following ingredients were prepared: HMDI, 55g IPDI, 2g MPEG1200, 126g UM90, 12g DMPA, 16g CHDM, 0.13g BiCat8108, and 93g acetone. The mixture was heated to 80℃ and reacted for 3 hours. Then, the temperature was lowered to 56℃, and 200g acetone and 104g NBP were added. The mixture was stirred until homogeneous, and the temperature was maintained at 36℃. 9g TEA was added and reacted for 5 minutes. After the reaction was completed, the prepolymer was poured into a dispersion cup, and 594g deionized water was added under high-speed shear at 1500 rpm. After dispersion, 10g IPDA was dissolved in 100g deionized water and added to the dispersion cup within 3 minutes. The mixture was reacted for 10 minutes. The acetone in the emulsion was removed by vacuum distillation at 50℃ to obtain a semi-transparent bluish-green waterborne polyurethane composition with 32% solids content and a particle size of 52nm.

[0070] Example 2

[0071] Add 35g to a four-necked flask equipped with a reflux condenser, thermometer, and mechanical stirrer. HMDI, 34g IPDI, 2.2g MPEG1200, 132g UM90, 9g DMPA, 0.1g BiCat8108, and 74g acetone were mixed and heated to 75℃ for 3 hours. Then, the temperature was lowered to 56℃, and 160g acetone and 82g NBP were added. The mixture was stirred until homogeneous, and the temperature was maintained at 39℃. 6.78g TEA was added and reacted for 5 minutes. After the reaction was completed, the prepolymer was poured into a dispersion cup, and 468g deionized water was added under high-speed shear at 1500 rpm. After dispersion, 6.4g IPDA was dissolved in 64g deionized water and added to the dispersion cup within 3 minutes. The mixture was reacted for 10 minutes. The acetone in the emulsion was removed by vacuum distillation at 45℃ to obtain a semi-transparent bluish-green waterborne polyurethane composition with a solid content of 32.5% and a particle size of 55nm.

[0072] Example 3

[0073] Add 42g to a four-necked flask equipped with a reflux condenser, thermometer, and mechanical stirrer. HMDI, 42g IPDI, 2.2g MPEG1200, 120g UM90, 9g DMPA, 8.6g CHDM, 0.11g BiCat8108, and 78g acetone were mixed and heated to 80℃ for 3 hours. Then, the temperature was lowered to 56℃, and 168g acetone and 86g NBP were added. The mixture was stirred until homogeneous, and the temperature was maintained at 36℃. 6.78g TEA was added and reacted for 5 minutes. After the reaction was completed, the prepolymer was poured into a dispersion cup, and 495g deionized water was added under high-speed shear at 1500 rpm. After dispersion, 7.2g IPDA dissolved in 72g deionized water was added to the dispersion cup within 3 minutes and reacted for 10 minutes. The acetone in the emulsion was removed by vacuum distillation at 50℃ to obtain a semi-transparent bluish-green waterborne polyurethane composition with 32% solids content and a particle size of 70nm.

[0074] Example 4

[0075] Add 42g to a four-necked flask equipped with a reflux condenser, thermometer, and mechanical stirrer. HMDI, 42g IPDI, 2.2g MPEG1200, 120g UM90, 9g DMPA, 8.6g CHDM, 0.11g BiCat8108, and 78g acetone were mixed and heated to 80℃ for 3 hours. Then, the temperature was lowered to 56℃, and 168g acetone and 44g NBP were added. The mixture was stirred until homogeneous, and the temperature was maintained at 36℃. 6.78g TEA was added and reacted for 5 minutes. After the reaction was completed, the prepolymer was poured into a dispersion cup, and 495g deionized water was added under high-speed shear at 1500 rpm. After dispersion, 7.2g IPDA dissolved in 72g deionized water was added to the dispersion cup within 3 minutes and reacted for 10 minutes. The acetone in the emulsion was removed by vacuum distillation at 50℃ to obtain a semi-transparent bluish-green waterborne polyurethane composition with 32% solids content and a particle size of 68nm.

[0076] Example 5

[0077] Add 42g to a four-necked flask equipped with a reflux condenser, thermometer, and mechanical stirrer. HMDI, 42g IPDI, 2.2g MPEG1200, 120g UM90, 9g DMPA, 8.6g CHDM, 0.11g BiCat8108, and 78g acetone were mixed and heated to 80℃ for 3 hours. Then, the temperature was lowered to 56℃, and 168g acetone and 116g NBP were added. The mixture was stirred until homogeneous, and the temperature was maintained at 36℃. 6.78g TEA was added and reacted for 5 minutes. After the reaction was completed, the prepolymer was poured into a dispersion cup, and 495g deionized water was added under high-speed shear at 1500 rpm. After dispersion, 7.2g IPDA dissolved in 72g deionized water was added to the dispersion cup within 3 minutes and reacted for 10 minutes. The acetone in the emulsion was removed by vacuum distillation at 50℃ to obtain a semi-transparent bluish-green waterborne polyurethane composition with 32% solids content and a particle size of 65nm.

[0078] Example 6

[0079] Add 45g to a four-necked flask equipped with a reflux condenser, thermometer, and mechanical stirrer. HMDI, 48g IPDI, 2g MPEG1200, 118g PNA1000, 11g DMPA, 13g CHDM, 0.12g BiCat8108, and 83g acetone were mixed and heated to 80℃ for 3 hours. Then, the temperature was lowered to 56℃, and 178g acetone and 92g NBP were added. The mixture was stirred until homogeneous, and the temperature was maintained at 36℃. 8.3g TEA was added and reacted for 5 minutes. After the reaction was completed, the prepolymer was poured into a dispersion cup, and 524g deionized water was added under high-speed shear at 1500 rpm. After dispersion, 7.6g IPDA was dissolved in 76g deionized water and added to the dispersion cup within 3 minutes. The mixture was reacted for 10 minutes. The acetone in the emulsion was removed by vacuum distillation at 50℃ to obtain a semi-transparent bluish-green waterborne polyurethane composition with 32% solids content and a particle size of 62nm.

[0080] Example 7

[0081] Add 43g to a four-necked flask equipped with a reflux condenser, thermometer, and mechanical stirrer. HMDI, 43g IPDI, 2.4g N120, 120g UM90, 9g DMBA, 6.4g NPG, 0.11g BiCat8108, and 78g acetone were mixed and heated to 80℃ for 3 hours. Then, the temperature was lowered to 56℃, and 168g acetone and 86g NBP were added. The mixture was stirred until homogeneous, and the temperature was maintained at 36℃. 6.78g TEA was added and reacted for 5 minutes. After the reaction was completed, the prepolymer was poured into a dispersion cup, and 494g deionized water was added under high-speed shear at 1500 rpm. After dispersion, 6.8g hydroxyethyl ethylenediamine was dissolved in 68g deionized water and added to the dispersion cup within 3 minutes. The mixture was reacted for 10 minutes. The acetone in the emulsion was removed by vacuum distillation at 50℃ to obtain a semi-transparent bluish-green waterborne polyurethane composition with 32% solids content and a particle size of 65nm.

[0082] Comparative Example 1

[0083] Compared with Example 3, the difference is that NMP is used instead of NBP.

[0084] Add 42g to a four-necked flask equipped with a reflux condenser, thermometer, and mechanical stirrer. HMDI, 42g IPDI, 2.2g MPEG1200, 120g UM90, 9g DMPA, 8.6g CHDM, 0.11g BiCat8108, and 78g acetone were mixed and heated to 80℃ for 3 hours. Then, the temperature was lowered to 56℃, and 168g acetone and 86g NMP were added. The mixture was stirred until homogeneous, and the temperature was maintained at 36℃. 6.78g TEA was added and reacted for 5 minutes. After the reaction was completed, the prepolymer was poured into a dispersion cup, and 495g deionized water was added under high-speed shear at 1500 rpm. After dispersion, 7.2g IPDA dissolved in 72g deionized water was added to the dispersion cup within 3 minutes and reacted for 10 minutes. The acetone in the emulsion was removed by vacuum distillation to obtain a semi-transparent bluish-green waterborne polyurethane composition with 32% solids content and a particle size of 76nm.

[0085] Comparative Example 2

[0086] Compared with Example 3, the difference is that NEP is used instead of NBP.

[0087] Add 42g to a four-necked flask equipped with a reflux condenser, thermometer, and mechanical stirrer. HMDI, 42g IPDI, 2.2g MPEG1200, 120g UM90, 9g DMPA, 8.6g CHDM, 0.11g BiCat8108, and 78g acetone were mixed and heated to 80℃ for 3 hours. Then, the temperature was lowered to 56℃, and 168g acetone and 86g NEP were added. The mixture was stirred until homogeneous, and the temperature was maintained at 36℃. 6.78g TEA was added and reacted for 5 minutes. After the reaction was completed, the prepolymer was poured into a dispersion cup, and 495g deionized water was added under high-speed shear at 1500 rpm. After dispersion, 7.2g IPDA dissolved in 72g deionized water was added to the dispersion cup within 3 minutes, and the mixture was reacted for 10 minutes. The acetone in the emulsion was removed by vacuum distillation to obtain a semi-transparent bluish-green waterborne polyurethane composition with a solid content of 32% and a particle size of 73nm.

[0088] Comparative Example 3

[0089] Compared with Example 3, the difference is that NBP is not added.

[0090] Add 42g to a four-necked flask equipped with a reflux condenser, thermometer, and mechanical stirrer. HMDI, 42g IPDI, 2.2g MPEG1200, 120g UM90, 9g DMPA, 8.6g CHDM, 0.11g BiCat8108, and 78g acetone were mixed and heated to 80℃ for 3 hours. Then, the temperature was lowered to 56℃ and 168g acetone was added. The mixture was stirred until homogeneous and the temperature was maintained at 36℃. 6.78g TEA was added and reacted for 5 minutes. After the reaction was completed, the prepolymer was poured into a dispersion cup and 495g deionized water was added under high-speed shear at 1500 rpm. After dispersion, 7.2g IPDA was dissolved in 72g deionized water and added to the dispersion cup within 3 minutes. The mixture was reacted for 10 minutes. The acetone in the emulsion was removed by vacuum distillation to obtain a semi-transparent bluish-green waterborne polyurethane composition with 32% solids content and a particle size of 82nm.

[0091] Comparative Example 4

[0092] Compared with Example 3, the difference is that NBP is added during the prepolymerization stage.

[0093] Add 42g to a four-necked flask equipped with a reflux condenser, thermometer, and mechanical stirrer. The following ingredients were prepared: HMDI, 42g IPDI, 2.2g MPEG1200, 120g UM90, 9g DMPA, 8.6g CHDM, 0.11g BiCat8108, 78g acetone, and 86g NBP. The mixture was heated to 80℃ and reacted for 3 hours. Then, the temperature was lowered to 56℃, and 168g acetone was added. The mixture was stirred until homogeneous, and the temperature was maintained at 36℃. 6.78g TEA was added and reacted for 5 minutes. After the reaction was completed, the prepolymer was poured into a dispersion cup, and 495g deionized water was added under high-speed shear at 1500 rpm. After dispersion, 7.2g IPDA was dissolved in 72g deionized water and added to the dispersion cup within 3 minutes. The mixture was reacted for 10 minutes. The acetone in the emulsion was removed by vacuum distillation to obtain a semi-transparent, bluish-green waterborne polyurethane composition with a solid content of 32% and a particle size of 77nm.

[0094] The performance indicators of the obtained waterborne polyurethane composition are shown in the table below:

[0095]

[0096] The experimental results above show that the waterborne polyurethane composition of the present invention has good adhesion, water resistance and anti-biting performance on plastic substrates, good yellowing effect and low sediment content. Its application performance is better than that of mainstream solvents in the industry, and it has great practical value for the application of waterborne polyurethane in the field of plastic paint.

[0097] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Any modifications or equivalent substitutions made to the present invention without departing from the spirit and scope thereof should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for preparing an aqueous polyurethane composition, characterized in that, The preparation method includes the following steps: S1: Synthetic isocyanate-terminated prepolymer; S2: After adding a diluent to the prepolymer and reacting it with a neutralization reaction, an aqueous polyurethane crude emulsion is obtained by dispersion; S3: Add an amino chain extender to the waterborne polyurethane crude emulsion to remove low-boiling-point solvents and obtain a waterborne polyurethane composition. Wherein, the isocyanate-terminated prepolymer of S1 is prepared by reacting raw materials containing the following components in a low-boiling-point solvent: polyisocyanate, macromolecular polyol, small molecule polyol, hydrophilic chain extender, monohydric alcohol and / or dihydric alcohol containing polyethylene oxide segments in the main chain and / or side chain. The diluent mentioned in S2 is N-butylpyrrolidone.

2. The preparation method according to claim 1, characterized in that, The polyisocyanate mentioned in S1 is one or more of aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates; And / or, the macromolecular polyol described in S1 is one or more of alcohol ether ester compounds containing at least two active hydrogens that can react with isocyanate groups; And / or, the small molecule polyols described in S1 are polyfunctional compounds with a molecular weight of less than 500 g / mol containing groups that can react with isocyanates; And / or, the hydrophilic chain extender described in S1 is an active hydrogen chain extender containing ionic groups or potential ionic groups that can react with isocyanates; And / or, the monohydric alcohol and / or dihydric alcohol containing polyethylene oxide segments in the main chain and / or side chain of S1 are polymer units containing polyethylene oxide segments containing 90-100 wt% ethylene oxide. And / or, the low-boiling solvent in S1 is an organic solvent with a boiling point below 100°C.

3. The preparation method according to claim 2, characterized in that, The amount of polyisocyanate used in S1 is 32-42 wt% of the isocyanate-terminated prepolymer. The amount of the macromolecular polyol used is 47-62.5% of the mass of the isocyanate-terminated prepolymer; The amount of the small molecule polyol used is 0-6 wt% of the isocyanate-terminated prepolymer. The amount of the hydrophilic chain extender is 4-5 wt% of the isocyanate-terminated prepolymer. The amount of monohydric alcohols and / or dihydric alcohols containing polyethylene oxide segments in the main chain and / or side chains is 0.5-1.2 wt% of the isocyanate-terminated prepolymer. The amount of the low-boiling-point solvent used is 0.8-1.5 times the mass of the isocyanate-terminated prepolymer; And / or, the polyisocyanate S1 is one or more of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, pentane diisocyanate, hexahydrotoluene diisocyanate, trimethylhexane diisocyanate, phenylene diisocyanate, 1,4-cyclohexane diisocyanate, dodecyl diisocyanate, 1,5-naphthalene diisocyanate and dicyclohexylmethane diisocyanate; And / or, the macromolecular polyol described in S1 is one or more of the following: polyethylene glycol, polypropylene glycol, polyethylene glycol-propylene glycol, polytetrahydrofuran ether diol, dimer acid polyester polyol, polyolefin polyol, polycaprolactone diol, polycarbonate diol, polyethylene adipate diol, 1,4-butanediol adipate diol, neopentyl adipate diol, 1,6-hexanediol adipate diol, and phthalic anhydride polyester polyol; The number-average molecular weight of the macromolecular polyol is 500-3000; And / or, the small molecule polyols described in S1 are one or more selected from ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 3-methylpentane-1,5-pentanediol, 1,6-hexanediol, neopentanediol, 1,4-cyclohexyldiethanol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 2-ethyl-3-propylpentanediol, 2,2-dimethylpentanediol, diethylene glycol, glycerol, and trimethylolpropane. And / or, the hydrophilic chain extender of S1 is one or more of dimethylolpropionic acid, dimethylolbutyric acid, amino acid, aminosulfonate, tartaric acid, N,N-dimethylolmaleamic acid, diaminobenzoic acid, and sodium dihydroxypropanesulfonate. And / or, the monohydric alcohol and / or dihydric alcohol containing polyethylene oxide segments in the main chain and / or side chain of S1 is Tegomer from TegoChemie. ® D-3403, Perstrop's Ymer TM One or more of N120 and MPEG1200 from Lotte Technology of South Korea; And / or, the low-boiling solvent of S1 is one or more of acetone, methyl ethyl ketone, cyclohexane, dichloromethane, dichloroethane, trichloroethane, ethyl acetate, pentane, heptane, and hexane.

4. The preparation method according to claim 3, characterized in that, S1 The polyisocyanate is dicyclohexylmethane diisocyanate and / or isophorone diisocyanate; And / or, the macromolecular polyol described in S1 is a polycarbonate diol; The number-average molecular weight of the macromolecular polyol is 800-2000; And / or, the small molecule polyol described in S1 is 1,4-cyclohexyldiethanol; And / or, the hydrophilic chain extender in S1 is dimethylolpropionic acid; And / or, the monohydric alcohol and / or dihydric alcohol containing polyethylene oxide segments in the main chain and / or side chain of S1 is MPEG1200 from Lotte Corporation of South Korea. And / or, the low-boiling solvent in S1 is acetone.

5. The preparation method according to claim 1 or 2, characterized in that, The reaction temperature in S1 is 60-90℃.

6. The preparation method according to claim 1, characterized in that, The neutralizing agent used in the neutralization reaction described in S2 is an organic or inorganic compound with neutralizing function.

7. The preparation method according to claim 6, characterized in that, The amount of diluent used in S2 is 18-52 wt% of the isocyanate-terminated prepolymer. And / or, the neutralizing agent described in S2 is one or more of sodium hydroxide, potassium hydroxide, triethylamine, N,N-dimethylethanolamine, dimethylcyclohexylamine, triethanolamine, methyldiethanolamine, diisopropanolamine, ethyldiisopropylamine, diisopropylcyclohexylamine, N-methylmorpholine, 2-amino-2-methyl-1-propanol, and ammonia. The amount of neutralizing agent is 3-3.5 wt% of the isocyanate-terminated prepolymer.

8. The preparation method according to claim 7, characterized in that, The neutralizing agent mentioned in S2 is triethylamine.

9. The preparation method according to claim 1, characterized in that, The neutralization temperature described in S2 is 35-45℃.

10. The preparation method according to claim 1, characterized in that, The amino chain extender described in S3 is a polyamine containing at least two active hydrogen atoms that can react with isocyanates.

11. The preparation method according to claim 10, characterized in that, The amino chain extender mentioned in S3 is one or more of the following: ethylenediamine, dicyclohexylmethanediamine, hydroxyethyl ethylenediamine, aminosiloxane, diethylenetriamine, triethylenetetramine, hexamethylenediamine, pentamethylenediamine, diethylenetriamine, isophoronediamine, and 4,4-diphenylmethanediamine; The amount of the amino chain extender is 3-4 wt% of the isocyanate-terminated prepolymer.

12. The preparation method according to claim 11, characterized in that, The amino chain extender mentioned in S3 is isophorone diamine.

13. The preparation method according to claim 1, characterized in that, The method for removing low-boiling-point solvents in S3 is vacuum distillation.

14. The preparation method according to claim 13, characterized in that, The temperature for vacuum distillation is 40-60℃.

15. A waterborne polyurethane composition, said composition being prepared by any one of claims 1-14, said waterborne polyurethane composition containing a diluent added after prepolymerization.

16. Use of a waterborne polyurethane composition, said composition being prepared by any one of claims 1-14, or being the composition of claim 15, said composition being used in the field of industrial coatings and plastic paints.

Images