Polyurethane polyol aqueous dispersion having super-high solid content, and solvent-free preparation method therefor

Abstract

The present invention provides a polyurethane polyol aqueous dispersion having a super-high solid content, and a solvent-free preparation method therefor. The polyurethane polyol aqueous dispersion comprises the components, calculated by mass percentage: 40-80 wt% polyurethane polyol, 0.01-2 wt% catalyst, 0.1-3 wt% neutralizing agent, and 20-60 wt% deionized water; the polyurethane polyol comprises 22-55 wt% polymer diol, 3-23 wt% polyisocyanate, 0.3-4% polyol, and 1-7 wt% a hydroxy acid compound. The polymer diol has a molecular weight between 200-1500, with four or more carbon atoms in the main chain repeating unit. Polymer diols with main chains of C4 or more are more lipophilic, making the prepared polyurethane polyol more likely to exhibit amphiphilic characteristics of both lipophilicity and hydrophilicity. This can effectively reduce the proportion of stretched polymer chains in the aqueous phase, enhance the dispersion ability of the polyurethane polyol in water, and consequently increase the overall solid content of the aqueous dispersion.

Description

Aqueous dispersion of polyurethane polyol with ultra-high solid content and solvent-free preparation method thereof Technical Field

[0001] The present invention relates to the technical field of polyurethane polyol aqueous dispersion, and in particular to an ultra-high solid content polyurethane polyol aqueous dispersion and a solvent-free preparation method thereof. Background Art

[0002] With the increasing awareness of health care, environmental protection, and law, the preparation process of polymer resins in the field of new chemical materials is gradually shifting from solvent-based to water-based. Waterborne hydroxyl resins are a type of water-based dispersion, mainly divided into polyacrylate polyol dispersions (OH-PAD), polyester polyol dispersions (OH-PED), and polyurethane polyol dispersions (OH-PUD). OH-PAD has the disadvantages of low solids, high viscosity, and a cured film that is sticky in hot and brittle in cold. OH-PED is easily hydrolyzed and dries slowly, and the cured film generally exhibits poor water resistance. Compared with OH-PAD and OH-PED, OH-PUD can flexibly adjust the performance of the coating film by adjusting the soft and hard segment content. Due to its high performance and low volatile organic solvent (VOC) content, the cured film is widely used in coatings, adhesives, leather, textiles and other fields, making it an ideal waterborne hydroxyl resin.

[0003] After searching, relevant reports on related research on polyurethane polyol dispersions have been found: Zhang Xudong et al. prepared OH-PUD by reacting diethanolamine (DEA) or ethylenediamine (EDA) with PU prepolymer. Since the PU prepolymer tends to react preferentially with EDA, the OH-PUD has lower hydroxyl functional groups and content, making it more difficult to cure; Liu et al. used the acetone method to react tromethamine with PU prepolymer to prepare OH-PUD; Xia Yamin et al. used the N-methylpyrrolidone method to react diethanolamine, 1,4-butanediol, and ethylene glycol with PU prepolymer to obtain OH-PUD; Patent CN 102597039B discloses a water-dispersible polyurethane. The preparation process of this patent uses an organic solvent. The polyurethane structure contains urea and hydroxyl groups, and the solid content is nearly 40%; Patent CN 109503798A discloses the preparation of a high-hydroxyl content polyurethane aqueous dispersion. The preparation process of this patent uses an organic solvent, and the solid content is nearly 40%. In the above reports, solvents are inevitably used in the preparation of polyurethane polyol dispersions, and there are no research or patent reports on high-curing and solvent-free technologies for polyurethane polyol dispersions.

[0004] There are also many reports on patents for high-solids waterborne polyurethanes: Patent CN 11132743A discloses a high-solids carbon dioxide-based cationic waterborne polyurethane and its preparation method. The preparation process uses a large amount of 2-butanone as a solvent, and the solid content of the resulting waterborne polyurethane resin can reach 60-63%, but the viscosity is as high as 600-900, which can easily lead to emulsion instability; Patent CN 111533881A discloses a method for preparing a waterborne high-solids polyurethane, which uses a small amount of acetone as a solvent, and the solid content of the resulting waterborne polyurethane resin can reach 45-48%; Patent CN1786055A discloses a two-component high-solids waterborne polyurethane and its preparation method and application. The preparation process uses acetone and other solvents, and the solid content of the resulting waterborne polyurethane resin can reach 50-54%, but the viscosity is not less than 450mPa.s.

[0005] Polyurethane (PU) polyol dispersions are usually obtained by using an excess of diol to terminate the isocyanate (NCO) groups of a PU prepolymer and then neutralizing and dispersing it to form a water-based hydroxyl resin. It can be cured into a film not only with an amino resin at high temperature, but also with a water-based isocyanate at low temperature. Compared with traditional solvent-based polyurethanes, polyurethane water-based dispersions have two common problems: 1) The latent heat of evaporation of water is high, the drying speed of water-based polyurethanes is slow, and the efficiency of use is low; 2) The solid content is low. Generally, the solid content of water-based polyurethanes is less than 30%. A large amount of water prolongs the curing time, making it difficult to meet actual use requirements. Therefore, high-solid, solvent-free, low-hydrophilic content water-based polyurethanes are more in line with the "5E" principle and the national "dual carbon" policy, and have important economic and practical value.

[0006] Summary of the Invention

[0007] In response to the deficiencies in the prior art, the present invention aims to provide an aqueous polyurethane polyol dispersion with an ultra-high solid content and a solvent-free preparation method thereof. Among the components of the aqueous polyurethane polyol dispersion, the molecular weight of the polymer diol is between 200 and 1500, the carbon atoms in the main chain repeating unit are more than 4, and the polymer diol with a main chain of C4 or more is more lipophilic, so that the prepared polyurethane polyol is more likely to have amphiphilic characteristics of both lipophilicity and hydrophilicity, can effectively reduce the extended chain ratio of the polymer chain in the aqueous phase, improve the dispersibility of the polyurethane polyol in water, and thus increase the solid content of the overall aqueous dispersion.

[0008] The first aspect of the present invention provides an ultra-high solid content polyurethane polyol aqueous dispersion, which includes the following components calculated by mass percentage: 40-80 wt% of polyurethane polyol, 0.01-2 wt% of catalyst, 0.1-3 wt% of neutralizer, and 20-60 wt% of deionized water. The polyurethane polyol includes 25-55 wt% of polymer diol, 3-23 wt% of polyisocyanate, 0.3-4 wt% of polyol, and 1-7 wt% of hydroxy acid compound.

[0009] In one embodiment, the number average molecular weight of the polymer diol is 200 to 1500, the molecular weight of the polyol is 60 to 400, and the number of carbon atoms in the main chain repeating unit of the polymer diol is greater than 4.

[0010] In one embodiment, the catalyst is one or more of dibutyltin dilaurate, stannous octoate, dibutyltin diacetate, N-methylmorpholine, N-methylimidazole, tetraisopropyl titanate, tetrabutyl titanate, di(dodecylsulfide)dibutyltin, dimethylethanolamine, dimethylcyclohexylamine, and triethylenediamine.

[0011] In one embodiment, the neutralizing agent is one or more of triethylamine, dimethylethanolamine, 1-ethylpiperidine, dimethylisopropylamine, diethylethanolamine, and 2-amino-2-dimethylpropanol.

[0012] In one embodiment, the polymer diol is one or more of polytetramethylene glycol, adipic acid-based polyester diol, polycaprolactone diol, polycarbonate diol, and polyester-polycarbonate copolymer diol.

[0013] In one embodiment, the polyisocyanate is one or more of toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, HDI trimer, and IPDI trimer.

[0014] In one embodiment, the polyol is one or more of ethylene glycol, propylene glycol, butylene glycol, trimethylolpropane, pentaerythritol, dimethyl-1,3-propanediol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 3-hydroxy-2,2-dimethyl-3-hydroxy-2,2-dimethylpropyl propionate, 1,4-cyclohexanedimethanol, trimethylpentanediol, β-hydroxyalkylamide, isosorbide, trimethylolethane, glycerol, and 1,2,6-hexanetriol.

[0015] In one embodiment, the hydroxy acid compound is one or more of dimethylol propionic acid, dimethylol butanoic acid, sodium 4,4'-dihydroxybutane sulfonate, and sodium ethylenedihydroxyethane sulfonate.

[0016] A second aspect of the present invention provides a solvent-free preparation method for the above-mentioned ultra-high solid content polyurethane polyol aqueous dispersion, characterized in that it comprises the following steps:

[0017] S1, adding the polymer diol, the polyol, and the hydroxy acid compound into a reaction kettle, heating to 80-160° C. and starting stirring;

[0018] S2, after the reaction liquid in step S1 is uniform, cool it to 60-90°C, add the catalyst and continue stirring, add the polyisocyanate after the reaction liquid is uniform, and heat it to 90-160°C to start the reaction;

[0019] S3. After the reaction is completed, the reaction solution is cooled to 70-110° C., and the neutralizing agent and the deionized water are added thereto;

[0020] S4, keeping the reaction solution in step S3 at 60-100° C. for 1-3 hours, cooling it to 40° C. after the insulation is completed, and filtering it to obtain the polyurethane polyol aqueous dispersion with ultra-high solid content.

[0021] In one embodiment, in step S2, the completion of the reaction is indicated by the mass fraction of free isocyanate in the reaction solution being less than 0.3 wt %.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. In the components of the ultra-high solid content polyurethane polyol aqueous dispersion provided by the present invention, the carbon atoms in the main chain repeating units of the polymer diol are more than 4. The polymer diol with a main chain of C4 or more is more lipophilic. The polyurethane polyol prepared therefrom is more likely to have amphiphilic properties of both lipophilicity and hydrophilicity, which can reduce the stretch chain ratio of the polymer chain in water, improve the dispersibility of the polyurethane polyol in water, and thus increase the solid content of the overall aqueous dispersion. In addition, the molecular weight of the polymer diol is between 200 and 1500. Too high a molecular weight will lead to an increase in the viscosity of the entire system and require additional solvent to dissolve and dilute the reaction substrate. At the same time, the hydrophilic structures on the main chain are relatively far apart, and a high solid content cannot be achieved.

[0024] 2. The other components in the ultra-high solid content polyurethane polyol aqueous dispersion provided by the present invention also play an important role in the entire aqueous dispersion: polyisocyanate can form a carbamate structure with the hydroxyl groups of the polymer diol or polyol, thereby improving the flexibility, low-temperature resistance, mechanical strength, wear resistance, corrosion resistance and other properties of the entire aqueous dispersion; polyol can increase the branching degree of the entire aqueous dispersion, thereby improving its heat resistance and regulating the length of the molecular chain and the hydroxyl content to adapt to different application scenarios; hydroxy acid compounds provide hydrophilicity to the entire polymer, thereby realizing the water-based resin.

[0025] 3. The ultra-high solid content polyurethane polyol aqueous dispersion provided by the present invention can also effectively improve the problem of poor tactile performance in coating products, providing a water-based coating resin with a "soft touch".

[0026] 4. The preparation method of an ultra-high solid content polyurethane polyol aqueous dispersion provided by the present invention replaces the traditional low-temperature prepolymerization method for polyurethane resin and adopts a high-temperature polymerization process to effectively reduce the viscosity of the overall system, thereby eliminating the addition of organic solvents and realizing a solvent-free synthesis process. It not only complies with the global environmental protection trend and the national "dual carbon" policy, but also can effectively reduce economic costs and enhance the competitiveness of products in the market. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0028] FIG1 is a particle size distribution curve of the ultra-high solid content polyurethane polyol aqueous dispersion prepared in Examples 1-4 and Comparative Example 1;

[0029] FIG2 is a gel permeation chromatography (GPC) molecular weight distribution curve of the ultra-high solid content polyurethane polyol aqueous dispersion prepared in Examples 1-4 and Comparative Example 1;

[0030] FIG3 is a differential scanning calorimetry (DSC) curve of the ultra-high solid content polyurethane polyol aqueous dispersion prepared in Examples 1-4 and Comparative Example 1. DETAILED DESCRIPTION

[0031] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0032] The first aspect of the present invention provides an ultra-high solid content polyurethane polyol aqueous dispersion, wherein the polyurethane polyol aqueous dispersion comprises the following components calculated by mass percentage: 40-80 wt% of polyurethane polyol, 0.01-2 wt% of catalyst, 0.1-3 wt% of neutralizer, and 20-60 wt% of deionized water, wherein the polyurethane polyol comprises 25-55 wt% of polymer diol, 3-23 wt% of polyisocyanate, 0.3-4 wt% of polyol, and 1-7 wt% of hydroxy acid compound; in the entire aqueous dispersion, each component plays an important role and contributes to the performance of the aqueous dispersion; wherein: in the polymer diol, the carbon atoms in the main chain repeating unit are more than 4, which is more likely to have lipophilicity, and the polyurethane polyol prepared therefrom is more likely to have amphiphilic properties of lipophilicity and hydrophilicity, which is conducive to emulsification. It can reduce the stretch chain ratio of the polymer chain in water, improve the dispersibility of polyurethane polyol in water, and thus increase the solid content of the overall aqueous dispersion; in addition, the molecular weight of the polymer diol is between 200 and 1500. Too high a molecular weight will cause the viscosity of the entire system to increase and require an additional solvent to dissolve the reaction system. At the same time, the hydrophilic structures on the main chain are far apart, and a high solid content cannot be achieved; adding polyisocyanate to the component can form a carbamate structure with the hydroxyl groups of the polymer diol or polyol, thereby improving the flexibility, low-temperature resistance, mechanical strength, wear resistance, corrosion resistance and other properties of the entire aqueous dispersion; polyols can increase the branching degree of the entire aqueous dispersion, thereby improving its heat resistance and regulating the length of the molecular chain and the hydroxyl content to adapt to different application scenarios; finally, the hydroxy acid compound provides hydrophilicity to the entire polymer, realizing the water-based resin.

[0033] In some embodiments, the number average molecular weight of the polymer diol is 200 to 1500, the molecular weight of the polyol is 60 to 400, and the number of carbon atoms in the main chain repeating unit of the polymer diol is greater than 4.

[0034] In some embodiments, the catalyst is one or more of dibutyltin dilaurate, stannous octoate, dibutyltin diacetate, N-methylmorpholine, N-methylimidazole, tetraisopropyl titanate, tetrabutyl titanate, di(dodecylsulfide)dibutyltin, dimethylethanolamine, dimethylcyclohexylamine, and triethylenediamine.

[0035] In some embodiments, the neutralizing agent is one or more of triethylamine, dimethylethanolamine, 1-ethylpiperidine, dimethylisopropylamine, diethylethanolamine, and 2-amino-2-dimethylpropanol.

[0036] In some embodiments, the polymer diol is one or more of polyoxypropylene diol, polytetramethylene glycol, adipic acid-based polyester diol, polycaprolactone diol, polycarbonate diol, and polyester-polycarbonate copolymer diol.

[0037] In some embodiments, the polyisocyanate is one or more of toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, HDI trimer, and IPDI trimer.

[0038] In some embodiments, the polyol is one or more of ethylene glycol, propylene glycol, butylene glycol, trimethylolpropane, pentaerythritol, dimethyl-1,3-propanediol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 3-hydroxy-2,2-dimethyl-3-hydroxy-2,2-dimethylpropyl propionate, 1,4-cyclohexanedimethanol, trimethylpentanediol, β-hydroxyalkylamide, isosorbide, trimethylolethane, glycerol, and 1,2,6-hexanetriol.

[0039] In some embodiments, the hydroxy acid compound is one or more of dimethylol propionic acid, dimethylol butanoic acid, sodium 4,4'-dihydroxybutane sulfonate, and sodium ethylenedihydroxyethane sulfonate.

[0040] The second aspect of the present invention further provides a solvent-free preparation method of the above-mentioned ultra-high solid content polyurethane polyol aqueous dispersion, comprising the following steps:

[0041] S1, adding the polymer diol, the polyol, and the hydroxy acid compound into a reaction kettle, heating to 80-160° C. and starting stirring;

[0042] S2, after the reaction liquid in step S1 is uniform, cool it to 60-90° C., add the catalyst and continue stirring, add the polyisocyanate after the reaction liquid is uniform, and raise the temperature to 90-160° C. to start the reaction; in this step, the addition of the catalyst reduces the reaction energy barrier of each component, thereby ensuring that the reaction activity of each component with the isocyanate is substantially the same, solving the technical problem that isocyanate preferentially reacts with the polyol and the hydroxy acid compound but not with the polymeric diol;

[0043] S3. After the reaction is completed, the reaction solution is cooled to 70-110° C., and the neutralizing agent and the deionized water are added thereto. In this step, the addition of the neutralizing agent can ionize the hydroxy acid compound, thereby increasing the hydrophilicity of the entire system and achieving a high solid content.

[0044] S4, keeping the reaction solution in step S3 at 60-100° C. for 1-3 hours, cooling it to 40° C. after the insulation is completed, and filtering it to obtain the polyurethane polyol aqueous dispersion with ultra-high solid content.

[0045] In some embodiments, in step S2, the completion of the reaction is indicated by the mass fraction of free isocyanate in the reaction solution being less than 0.3 wt %.

[0046] In the preparation method of the above-mentioned ultra-high solid content polyurethane polyol aqueous dispersion, the traditional low-temperature prepolymerization method for polyurethane resin is replaced by a high-temperature polymerization process, which effectively reduces the viscosity of the overall system, thereby eliminating the addition of organic solvents and realizing a solvent-free synthesis process. This not only complies with the global environmental protection trend and the country's "dual carbon" policy, but also can effectively reduce economic costs and enhance the competitiveness of products in the market.

[0047] The present invention is further described below by way of examples:

[0048] Example 1

[0049] This embodiment provides an ultra-high solid content polyurethane polyol aqueous dispersion, which is prepared from the following components in percentage by mass:

[0050] Catalyst: dibutyltin dilaurate 0.09%; neutralizer: N,N-dimethylethanolamine 1.2%; polymer diol: polybutylene adipate with a molecular weight of 1000 (trade name: CMA-1044) 45.7%; polyisocyanate: dicyclohexylmethane-4,4-diisocyanate 13.4%; polyol: trimethylolpropane 1.9%; hydroxy acid compound: dimethylolpropionic acid 2.7%; deionized water: 35.0%.

[0051] The preparation method of the ultra-high solid content polyurethane polyol aqueous dispersion in this embodiment is as follows:

[0052] In a reaction kettle equipped with a stirrer and a thermometer, polymer diol, hydroxy acid compound and polyol are added in sequence and mixed evenly, and the temperature is slowly raised to 130-140°C, maintained at 130°C for 15 minutes, cooled to 90°C after the insulation, and when the temperature reaches 90°C, a catalyst is added to the reaction kettle, and polyisocyanate is added after stirring for 5 minutes, and then the temperature is raised to 140°C for reaction; the isocyanate (NCO) content is determined according to HG / T 2409-1992, and when the NCO value is lower than 3 mg / g, the temperature is lowered to below 100°C, a neutralizer is added, and after mixing for 5 minutes, deionized water is added dropwise to the reaction kettle within 20 minutes, and the temperature is raised to 80°C and maintained for 2 hours after the insulation is completed. The temperature is lowered and the material is discharged to obtain an ultra-high solid content polyurethane polyol aqueous dispersion.

[0053] Example 2

[0054] This embodiment provides an ultra-high solid content polyurethane polyol aqueous dispersion, which is prepared from the following components in percentage by mass:

[0055] Catalyst: dibutyltin dilaurate 0.07%; Neutralizer: N,N-dimethylethanolamine 1.0%; Polymer diol: Polytetramethylene glycol with a molecular weight of 1000 (trade name: 1000) 36.3%; polyisocyanate: dicyclohexylmethane-4,4-diisocyanate 10.7%; polyol: trimethylolpropane 1.5%; hydroxy acid compound: dimethylolpropionic acid 2.1%; deionized water: 48.3%.

[0056] The preparation method of the ultra-high solid content polyurethane polyol aqueous dispersion in this embodiment is as follows:

[0057] In a reaction kettle equipped with a stirrer and a thermometer, polymer diol, hydroxy acid compound and polyol are added in sequence and mixed evenly, and the temperature is slowly raised to 130-140°C, maintained at 130°C for 15 minutes, cooled to 90°C after the insulation, and when the temperature reaches 90°C, a catalyst is added to the reaction kettle, and polyisocyanate is added after stirring for 5 minutes, and then the temperature is raised to 140°C for reaction; the isocyanate (NCO) content is determined according to HG / T 2409-1992, and when the NCO value is lower than 3 mg / g, the temperature is lowered to below 100°C, a neutralizer is added, and after mixing for 5 minutes, deionized water is added dropwise to the reaction kettle within 20 minutes, and the temperature is raised to 80°C and maintained for 2 hours after the insulation is completed. The temperature is lowered and the material is discharged to obtain an ultra-high solid content polyurethane polyol aqueous dispersion.

[0058] Example 3

[0059] This embodiment provides an ultra-high solid content polyurethane polyol aqueous dispersion, which is prepared from the following components in percentage by mass:

[0060] Catalyst: dibutyltin dilaurate 0.07%; Neutralizer: N,N-dimethylethanolamine 1.0%; Polymer diol: Polyester polycarbonate copolyol with a molecular weight of 1000 (trade name: C1100) 36.1%; polyisocyanate: dicyclohexylmethane-4,4-diisocyanate 10.6%; polyol: trimethylolpropane 1.5%; hydroxy acid compound: dimethylolpropionic acid 2.1%; deionized water: 48.7%.

[0061] The preparation method of the ultra-high solid content polyurethane polyol aqueous dispersion in this embodiment is as follows:

[0062] In a reaction kettle equipped with a stirrer and a thermometer, polymer diol, hydroxy acid compound and polyol are added in sequence and mixed evenly, and the temperature is slowly raised to 130-140°C, maintained at 130°C for 15 minutes, cooled to 90°C after the insulation, and when the temperature reaches 90°C, a catalyst is added to the reaction kettle, and polyisocyanate is added after stirring for 5 minutes, and then the temperature is raised to 140°C for reaction; the isocyanate (NCO) content is determined according to HG / T 2409-1992, and when the NCO value is lower than 3 mg / g, the temperature is lowered to below 100°C, a neutralizer is added, and after mixing for 5 minutes, deionized water is added dropwise to the reaction kettle within 20 minutes, and the temperature is raised to 80°C and maintained for 2 hours after the insulation is completed. The temperature is lowered and the material is discharged to obtain an ultra-high solid content polyurethane polyol aqueous dispersion.

[0063] Example 4

[0064] This embodiment provides an ultra-high solid content polyurethane polyol aqueous dispersion, which is prepared from the following components in percentage by mass:

[0065] Catalyst: dibutyltin dilaurate 0.08%; Neutralizer: N,N-dimethylethanolamine 1.2%; Polymer diol: Polycarbonate diol with a molecular weight of 1000 (trade name: DURANOL TM T5651) 43.4%; polyisocyanate: dicyclohexylmethane-4,4-diisocyanate 12.7%; polyol: trimethylolpropane 1.8%; hydroxy acid compound: dimethylolpropionic acid 2.6%; deionized water: 38.3%.

[0066] The preparation method of the ultra-high solid content polyurethane polyol aqueous dispersion in this embodiment is as follows:

[0067] In a reaction kettle equipped with a stirrer and a thermometer, polymer diol, hydroxy acid compound and polyol are added in sequence and mixed evenly, and the temperature is slowly raised to 130-140°C, maintained at 130°C for 15 minutes, cooled to 90°C after the insulation, and when the temperature reaches 90°C, a catalyst is added to the reaction kettle, and polyisocyanate is added after stirring for 5 minutes, and then the temperature is raised to 140°C for reaction; the isocyanate (NCO) content is determined according to HG / T 2409-1992, and when the NCO value is lower than 3 mg / g, the temperature is lowered to below 100°C, a neutralizer is added, and after mixing for 5 minutes, deionized water is added dropwise to the reaction kettle within 20 minutes, and the temperature is raised to 80°C and maintained for 2 hours after the insulation is completed. The temperature is lowered and the material is discharged to obtain an ultra-high solid content polyurethane polyol aqueous dispersion.

[0068] Example 5

[0069] This embodiment provides an ultra-high solid content polyurethane polyol aqueous dispersion, which is prepared from the following components in percentage by mass:

[0070] Catalyst: 1.93% dibutyltin dilaurate; Neutralizer: 1.4% N,N-dimethylethanolamine; Polymer diol: 54.2% polybutylene adipate (trade name: CMA-1044) with a molecular weight of 1000; Polyisocyanate: 15.9% dicyclohexylmethane-4,4-diisocyanate; Polyol: 2.3% trimethylolpropane; Hydroxy acid compound: 3.2% dimethylolpropionic acid; Deionized water: 21.2%.

[0071] The preparation method of the ultra-high solid content polyurethane polyol aqueous dispersion in this embodiment is as follows:

[0072] In a reaction kettle equipped with a stirrer and a thermometer, polymer diol, hydroxy acid compound and polyol are added in sequence and mixed evenly, and the temperature is slowly raised to 130-140°C, maintained at 130°C for 15 minutes, cooled to 90°C after the insulation, and when the temperature reaches 90°C, a catalyst is added to the reaction kettle, and polyisocyanate is added after stirring for 5 minutes, and then the temperature is raised to 140°C for reaction; the isocyanate (NCO) content is determined according to HG / T 2409-1992, and when the NCO value is lower than 3 mg / g, the temperature is lowered to below 100°C, a neutralizer is added, and after mixing for 5 minutes, deionized water is added dropwise to the reaction kettle within 20 minutes, and the temperature is raised to 80°C and maintained for 2 hours after the insulation is completed. The temperature is lowered and the material is discharged to obtain an ultra-high solid content polyurethane polyol aqueous dispersion.

[0073] Example 6

[0074] This embodiment provides an ultra-high solid content polyurethane polyol aqueous dispersion, which is prepared from the following components in percentage by mass:

[0075] Catalyst: 1.13% dibutyltin dilaurate; Neutralizer: 0.8% N,N-dimethylethanolamine; Polymer diol: 25.6% polybutylene adipate (trade name: CMA-1044) with a molecular weight of 1000; Polyisocyanate: 8.9% dicyclohexylmethane-4,4-diisocyanate; Polyol: 2.0% trimethylolpropane; Hydroxy acid compound: 1.8% dimethylolpropionic acid; Deionized water: 59.9%.

[0076] The preparation method of the ultra-high solid content polyurethane polyol aqueous dispersion in this embodiment is as follows:

[0077] In a reaction kettle equipped with a stirrer and a thermometer, polymer diol, hydroxy acid compound and polyol are added in sequence and mixed evenly, and the temperature is slowly raised to 130-140°C, maintained at 130°C for 15 minutes, cooled to 90°C after the insulation, and when the temperature reaches 90°C, a catalyst is added to the reaction kettle, and polyisocyanate is added after stirring for 5 minutes, and then the temperature is raised to 140°C for reaction; the isocyanate (NCO) content is determined according to HG / T 2409-1992, and when the NCO value is lower than 3 mg / g, the temperature is lowered to below 100°C, a neutralizer is added, and after mixing for 5 minutes, deionized water is added dropwise to the reaction kettle within 20 minutes, and the temperature is raised to 80°C and maintained for 2 hours after the insulation is completed. The temperature is lowered and the material is discharged to obtain an ultra-high solid content polyurethane polyol aqueous dispersion.

[0078] Example 7

[0079] This embodiment provides an ultra-high solid content polyurethane polyol aqueous dispersion, which is prepared from the following components in percentage by mass:

[0080] Catalyst: dibutyltin dilaurate 0.06%; Neutralizer: N,N-dimethylethanolamine 1.6%; Polymer diol: polybutylene adipate with a molecular weight of 1000 (trade name: CMA-1044) 29.5%; Polyisocyanate: dicyclohexylmethane-4,4-diisocyanate 22.0%; Polyol: trimethylolpropane 3.5%; Hydroxy acid compound: dimethylolpropionic acid 3.6%; Deionized water: 39.8%.

[0081] The preparation method of the ultra-high solid content polyurethane polyol aqueous dispersion in this embodiment is as follows:

[0082] In a reaction kettle equipped with a stirrer and a thermometer, polymer diol, hydroxy acid compound and polyol are added in sequence and mixed evenly, and the temperature is slowly raised to 130-140°C, maintained at 130°C for 15 minutes, cooled to 90°C after the insulation, and when the temperature reaches 90°C, a catalyst is added to the reaction kettle, and polyisocyanate is added after stirring for 5 minutes, and then the temperature is raised to 140°C for reaction; the isocyanate (NCO) content is determined according to HG / T 2409-1992, and when the NCO value is lower than 3 mg / g, the temperature is lowered to below 100°C, a neutralizer is added, and after mixing for 5 minutes, deionized water is added dropwise to the reaction kettle within 20 minutes, and the temperature is raised to 80°C and maintained for 2 hours after the insulation is completed. The temperature is lowered and the material is discharged to obtain an ultra-high solid content polyurethane polyol aqueous dispersion.

[0083] Example 8

[0084] This embodiment provides an ultra-high solid content polyurethane polyol aqueous dispersion, which is prepared from the following components in percentage by mass:

[0085] Catalyst: dibutyltin dilaurate 0.05%; neutralizer: N,N-dimethylethanolamine 3.0%; polymer diol: polybutylene adipate with a molecular weight of 1000 (trade name: CMA-1044) 26.2%; polyisocyanate: dicyclohexylmethane-4,4-diisocyanate 16.6%; polyol: trimethylolpropane 0.4%; hydroxy acid compound: dimethylolpropionic acid 7.0%; deionized water: 46.8%.

[0086] The preparation method of the ultra-high solid content polyurethane polyol aqueous dispersion in this embodiment is as follows:

[0087] In a reaction kettle equipped with a stirrer and a thermometer, polymer diol, hydroxy acid compound and polyol are added in sequence and mixed evenly, and the temperature is slowly raised to 130-140°C, maintained at 130°C for 15 minutes, cooled to 90°C after the insulation, and when the temperature reaches 90°C, a catalyst is added to the reaction kettle, and polyisocyanate is added after stirring for 5 minutes, and then the temperature is raised to 140°C for reaction; the isocyanate (NCO) content is determined according to HG / T 2409-1992, and when the NCO value is lower than 3 mg / g, the temperature is lowered to below 100°C, a neutralizer is added, and after mixing for 5 minutes, deionized water is added dropwise to the reaction kettle within 20 minutes, and the temperature is raised to 80°C and maintained for 2 hours after the insulation is completed. The temperature is lowered and the material is discharged to obtain an ultra-high solid content polyurethane polyol aqueous dispersion.

[0088] Example 9

[0089] This embodiment provides an ultra-high solid content polyurethane polyol aqueous dispersion, which is prepared from the following components in percentage by mass:

[0090] Catalyst: 1.1% dibutyltin dilaurate; Neutralizer: 0.8% N,N-dimethylethanolamine; Polymer diol: 30.3% polybutylene adipate (trade name: CMA-1044) with a molecular weight of 1000; Polyisocyanate: 6.0% dicyclohexylmethane-4,4-diisocyanate; Polyol: 0.3% trimethylolpropane; Hydroxy acid compound: 1.8% dimethylolpropionic acid; Deionized water: 59.7%.

[0091] The preparation method of the ultra-high solid content polyurethane polyol aqueous dispersion in this embodiment is as follows:

[0092] In a reaction kettle equipped with a stirrer and a thermometer, polymer diol, hydroxy acid compound and polyol are added in sequence and mixed evenly, and the temperature is slowly raised to 130-140°C, maintained at 130°C for 15 minutes, cooled to 90°C after the insulation, and when the temperature reaches 90°C, a catalyst is added to the reaction kettle, and polyisocyanate is added after stirring for 5 minutes, and then the temperature is raised to 140°C for reaction; the isocyanate (NCO) content is determined according to HG / T 2409-1992, and when the NCO value is lower than 3 mg / g, the temperature is lowered to below 100°C, a neutralizer is added, and after mixing for 5 minutes, deionized water is added dropwise to the reaction kettle within 20 minutes, and the temperature is raised to 80°C and maintained for 2 hours after the insulation is completed. The temperature is lowered and the material is discharged to obtain an ultra-high solid content polyurethane polyol aqueous dispersion.

[0093] Comparative Example 1

[0094] In this comparative example, the polymer diol component and the deionized water component are different from those in Example 1, and the composition and proportion of other raw materials, the preparation method, and the test indicators are the same as those in Example 1:

[0095] Catalyst: dibutyltin dilaurate 0.05%; neutralizer: N,N-dimethylethanolamine 0.69%; polymer diol: polybutylene adipate with a molecular weight of 1000 (trade name: CMA-1044) 26.12%; polyisocyanate: dicyclohexylmethane-4,4-diisocyanate 7.66%; polyol: trimethylolpropane 1.09%; hydroxy acid compound: dimethylolpropionic acid 1.54%; deionized water: 62.86%.

[0096] Comparative Example 2

[0097] In this comparative example, the polymer diol component, polyol component, and deionized water component are different from those in Example 1. In addition, due to the high viscosity of the synthesis system, a solvent component, N-methylpyrrolidone, is added. The composition and proportion of other raw materials, preparation method, and test indicators are the same as those in Example 1:

[0098] Catalyst: dibutyltin dilaurate 0.06%; neutralizer: N,N-dimethylethanolamine 0.85%; polymer diol: polybutylene adipate with a molecular weight of 2000 (trade name: CMA-44) 16.2%; polyisocyanate: dicyclohexylmethane-4,4-diisocyanate 9.5%; polyol: trimethylolpropane 2.8%; hydroxy acid compound: dimethylolpropionic acid 1.9%; deionized water: 60.5%; solvent: N-methylpyrrolidone 8.1%.

[0099] Comparative Example 3

[0100] In this comparative example, the deionized water component and the temperature in the preparation method are different from those in Example 1. In addition, due to the high viscosity of the synthesis system, the solvent component: 2-butanone is added. The composition and proportion of other raw materials, the preparation method, and the test indicators are the same as those in Example 1:

[0101] Catalyst: dibutyltin dilaurate 0.06%; neutralizer: N,N-dimethylethanolamine 0.9%; polymer diol: polybutylene adipate with a molecular weight of 1000 (trade name: CMA-1044) 32.1%; polyisocyanate: dicyclohexylmethane-4,4-diisocyanate 9.4%; polyol: trimethylolpropane 1.3%; hydroxy acid compound: dimethylolpropionic acid 1.9%; deionized water: 44.3%; solvent: 2-butanone 10.0%.

[0102] The preparation method of the polyurethane polyol aqueous dispersion with ultra-high solid content in this comparative example is:

[0103] In a reaction kettle equipped with a stirrer and a thermometer, polymer diol, hydroxy acid compound and polyol are added in sequence and mixed evenly, and the temperature is slowly raised to 60-70°C and maintained at 65°C for 15 minutes. After the insulation is completed, a catalyst is added to the reaction kettle, and polyisocyanate is added after stirring for 5 minutes. The temperature is then raised to 70°C for reaction (due to excessive viscosity of the resin during the reaction, solvent 2-butanone is added to reduce the viscosity); the isocyanate (NCO) content is determined according to HG / T 2409-1992. When the reaction reaches an NCO value below 3 mg / g, the temperature is lowered to below 60°C, a neutralizer is added, and after mixing for 5 minutes, deionized water is dropwise added to the reaction kettle over 20 minutes. After the addition is completed, the temperature is raised to 70°C and maintained for 2 hours. After the insulation is completed, the temperature is lowered and the material is discharged to obtain a polyurethane polyol aqueous dispersion.

[0104] Experimental example

[0105] The results of viscosity, pH, solid content, particle size and Zeta potential, fineness, gel permeation chromatography (GPC) and thermal property tests of the ultra-high solid content polyurethane polyol aqueous dispersions prepared in Examples 1-9 and Comparative Examples 1-3 are listed in Tables 1-2. The test instruments and methods are as follows: the viscosity test was performed using a cone and plate viscometer CAP2000+ viscosity tester from Brookfield, USA, at a temperature of 25±0.5°C, a rotor No. 10, and a speed of 250s. -1; A Leizhi PHS-25 laboratory pH meter was used for pH testing; the solid content was determined in accordance with the national standard GB / T 1725-2007, the temperature was 125°C, the baking time was 60 min, and the sample size was 1 g; the particle size and Zeta potential were determined using the Zetasizer Nano ZS90 laser particle size analyzer from Malvern, UK; the fineness test was performed in accordance with the national standard GB / T 1724-2019; a 1515 gel permeation chromatograph from Waters, USA, PS was used as the standard sample, THF was used as the mobile phase, the column temperature was 40°C, the flow rate was 1 mL / min, and the injection volume was 50 μL, the molecular weight and molecular weight distribution of the sample were determined; a DSC 8500 differential scanning calorimeter from TA Instruments, USA, was used to test the thermal properties of the sample. The test was carried out under a nitrogen atmosphere, the temperature range was -90 to 150°C, the heating rate was 3°C / min, the cooling rate was 20°C / min, and the sample weight was 5 to 10 mg.

[0106] Table 1 Test results of technical parameters of the ultra-high solid content polyurethane polyol aqueous dispersions prepared in Examples 1-9 and Comparative Examples 1-3

[0107] Table 2 Gel chromatography (GPC) data of ultra-high solid content polyurethane polyol aqueous dispersions prepared in Examples 1-4 and Comparative Example 1

[0108] As shown in Table 1, the polyurethane polyol aqueous dispersions prepared in Examples 1-9 all exhibited the characteristics of high solid content. The particle size, fineness, and Zeta potential in Table 1 indicate that the polyurethane polyol aqueous dispersions have good stability. Except for Examples 5 and 7, the other examples all exhibited low viscosity characteristics (viscosity less than 300 mPa.s). Among them, the solid content of Example 1 reached 65.0%. Compared with Comparative Example 1, the solid content index in Table 1 shows that the polyurethane polyol aqueous dispersion prepared in Example 1 has a higher solid content, which indicates that the polymer diol with more than 4 carbon atoms in the main chain repeating unit is more lipophilic, making it easier for the prepared polyurethane polyol to have amphiphilic characteristics of lipophilicity and hydrophilicity, which is conducive to emulsification and can reduce the stretch chain ratio of the polymer chain in water, improve the dispersibility of the polyurethane polyol in water, and thus make it easier for the prepared polyurethane polyol aqueous dispersion to obtain ultra-high solid content; compared with Comparative Example 2, the dispersion particle size, Zeta potential, and fineness in Table 1 are all higher. The indexes of degree and whether it contains organic solvents show that the aqueous polyurethane polyol dispersion prepared in Example 1 can be solvent-free, have higher solid content and dispersion stability, and also illustrate that the polymer diol with a molecular weight lower than 1500 can effectively reduce the viscosity of the entire system, avoid the use of organic solvents, and shorten the distance between the hydrophilic structures on the main chain, making it easier to achieve a solvent-free process and obtain an ultra-high solid and stable aqueous dispersion; compared with Comparative Example 3, the dispersion Zeta potential, solid content, and whether it contains organic solvents in Table 1 show that the aqueous polyurethane polyol dispersion prepared in Example 1 is solvent-free, and has higher solid content and dispersion stability, further illustrating that the high-temperature prepolymerization process effectively reduces the viscosity of the reaction system and eliminates the addition of organic solvents, which not only solves the swelling effect of the solvent on the dispersion, but also realizes a solvent-free synthesis process. At the same time, the high-temperature prepolymerization process makes the polymer main chain more stereotyped by reducing the reaction activity barrier, thereby making it easier to achieve ultra-high solid and the prepared dispersion more stable.

[0109] As shown in Table 1 and Figure 1, the polyurethane polyol aqueous dispersions prepared in Examples 1-4 all show nanoscale properties, and their particle size distribution is narrow and the particle size is relatively uniform. While being highly representative, it also further proves that the above-mentioned aqueous dispersions have good stability and a wide range of application scenarios.

[0110] As shown in Figure 3, the glass transition temperatures (Tg) of Examples 1-4 are all lower than 0°C, and the Tg of Examples 1 and 2 is as low as -45°C. When polyurethane polyols with lower glass transition temperatures are used in coating systems, they can enhance the "soft touch effect" of the coating. In addition, they can also be used in combination with water-based isocyanates. In addition to coatings, polyurethane polyols with low Tg characteristics also have potential application prospects in the field of two-component adhesives.

[0111] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. An ultra-high solid content polyurethane polyol aqueous dispersion, characterized in that: The polyurethane polyol aqueous dispersion includes the following components calculated by mass percentage: 40-80 wt% of polyurethane polyol, 0.01-2 wt% of catalyst, 0.1-3 wt% of neutralizer, and 20-60 wt% of deionized water. The polyurethane polyol includes 25-55 wt% of polymer diol, 3-23 wt% of polyisocyanate, 0.3-4 wt% of polyol, and 1-7 wt% of hydroxy acid compound.

2. The ultra-high solid content polyurethane polyol aqueous dispersion according to claim 1, characterized in that: The number average molecular weight of the polymer diol is 200 to 1500, the molecular weight of the polyol is 60 to 400, and the number of carbon atoms in the main chain repeating unit of the polymer diol is greater than 4.

3. The ultra-high solid content polyurethane polyol aqueous dispersion according to claim 1, characterized in that: The catalyst is one or more of dibutyltin dilaurate, stannous octoate, dibutyltin diacetate, N-methylmorpholine, N-methylimidazole, tetraisopropyl titanate, tetrabutyl titanate, di(dodecylsulfide)dibutyltin, dimethylethanolamine, dimethylcyclohexylamine, and triethylenediamine.

4. The ultra-high solid content polyurethane polyol aqueous dispersion according to claim 1, characterized in that: The neutralizing agent is one or more of triethylamine, dimethylethanolamine, 1-ethylpiperidine, dimethylisopropylamine, diethylethanolamine, and 2-amino-2-dimethylpropanol.

5. The ultra-high solid content polyurethane polyol aqueous dispersion according to claim 1, characterized in that: The polymer diol is one or more of polytetramethylene glycol, adipic acid polyester diol, polycaprolactone diol, polycarbonate diol, and polyester-polycarbonate copolymer diol.

6. The ultra-high solid content polyurethane polyol aqueous dispersion according to claim 1, characterized in that: The polyisocyanate is one or more of toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, HDI trimer, and IPDI trimer.

7. The ultra-high solid content polyurethane polyol aqueous dispersion according to claim 1, characterized in that: The polyol is one or more of ethylene glycol, propylene glycol, butylene glycol, trimethylolpropane, pentaerythritol, dimethyl-1,3-propanediol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 3-hydroxy-2,2-dimethyl-3-hydroxy-2,2-dimethylpropyl propionate, 1,4-cyclohexanedimethanol, trimethylpentanediol, β-hydroxyalkylamide, isosorbide, trimethylolethane, glycerol, and 1,2,6-hexanetriol.

8. The ultra-high solid content polyurethane polyol aqueous dispersion according to claim 1, characterized in that: The hydroxy acid compound is one or more of dimethylol propionic acid, dimethylol butyric acid, sodium 4,4'-dihydroxybutane sulfonate, and sodium ethylenedihydroxyethane sulfonate.

9. A solvent-free preparation method of the ultra-high solid content polyurethane polyol aqueous dispersion according to claims 1 to 8, characterized in that: The following steps are involved: S1, adding the polymer diol, the polyol, and the hydroxy acid compound into a reaction kettle, heating to 80-160° C. and starting stirring; S2, after the reaction liquid in step S1 is uniform, cool it to 60-90°C, add the catalyst and continue stirring, add the polyisocyanate after the reaction liquid is uniform, and heat it to 90-160°C to start the reaction; S3. After the reaction is completed, the reaction solution is cooled to 70-110° C., and the neutralizing agent and the deionized water are added thereto; S4, keeping the reaction solution in step S3 at 60-100° C. for 1-3 hours, cooling it to 40° C. after the insulation is completed, and filtering it to obtain the polyurethane polyol aqueous dispersion with ultra-high solid content.

10. The solvent-free preparation method of the ultra-high solid content polyurethane polyol aqueous dispersion according to claim 9, characterized in that: In step S2, the completion of the reaction is indicated by the mass fraction of free isocyanate in the reaction solution being less than 0.3 wt%.

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