A short-oil-content urethane oil-water dispersion without desolventizing process and its preparation method

Abstract

This invention discloses a short-oil-content urethane oil-water dispersion and its preparation method without solvent removal process, belonging to the field of waterborne resins for coatings. First, an ultra-low viscosity terminal hydroxyl diol intermediate is prepared by ring-opening esterification of unsaturated fatty acids and diglycidyl ether. Then, a urethane oil prepolymer is synthesized by chain extension reaction of diisocyanate monomer, hydrophilic chain extender, small molecule diol, and the above-prepared terminal hydroxyl diol intermediate. After neutralization with triethylamine and thorough emulsification with deionized water, it is further treated with a post-chain extender to obtain an urethane oil-water dispersion with a solid content of 40-45%, a viscosity of 50-300 mPa·s, and an oil content of 30-40%. A large amount of nonpolar C 18 Unsaturated alkane segments are regularly distributed in a comb-like structure on the molecular side chains of the urethane oil prepolymer, which reduces the polarity of the system and the intermolecular interaction forces, thereby significantly reducing the viscosity of the prepolymer and achieving effective water emulsification without the need for additional cosolvents.

Description

Technical Field

[0001] This invention relates to the field of waterborne resins for coatings, and specifically to a short-oil-content urethane oil-water dispersion without solvent removal process and its preparation method. Background Technology

[0002] As a fatty acid-modified polyurethane resin, urethane oil is widely used in coating applications such as woodwork, flooring, and metal corrosion protection due to its advantages such as fast drying, abrasion resistance, and high gloss. With increasingly stringent environmental policies, the application of traditional solvent-based urethane oils is severely restricted, making water-based formulations the mainstream development direction in the industry. Self-emulsification has thus become the core process for preparing water-based urethane oils. The self-emulsification process first involves the high-temperature alcoholysis of drying or semi-drying vegetable oils with glycerol to obtain a glycerol ester polyol intermediate. This intermediate is then reacted with an ionic hydrophilic chain extender, a small molecule polyol, and a polyisocyanate to obtain a hydroxyl-terminated polyurethane prepolymer. After neutralization with a tertiary amine, this prepolymer is strongly dispersed and emulsified with water to finally obtain an aqueous dispersion of urethane oil.

[0003] Current mainstream self-emulsification methods have significant technical defects, the core problem stemming from the inherent characteristics of glycerol ester polyol intermediates. These intermediates are mixtures of monoglyceride, diglyceride, and triglyceride esters, directly leading to a high color number, wide molecular weight distribution, and low chain extension efficiency in the subsequently synthesized urethane oils. Simultaneously, the emulsions exhibit high viscosity and poor storage stability, failing to meet the application requirements of high-end coatings. To optimize performance, existing technologies attempt to mitigate the impact of these defects through formulation improvements. Chinese invention patent CN101048477B uses a combination of fatty acid-modified epoxy compounds and natural oil-modified polyols, along with a multi-double-bond reactive diluent to reduce system viscosity, significantly decreasing the amount of organic solvents such as NMP (N-methylpyrrolidone). However, this still does not eliminate the problems of mixed glycerol ester polyol raw materials, high color number, and insufficient storage stability, and the residual NMP prevents true solvent-free production.

[0004] While some improved processes have been developed, they have yet to overcome core bottlenecks. Chinese invention patent application CN116003720A uses diglycidyl ether to ring-open esterify fatty acids to prepare an epoxy ester intermediate, which is then grafted with polyurethane and water-based to obtain the final product. However, this process has two major drawbacks: first, the oil content of the urethane oil emulsion is only 2%~10%, resulting in extremely low oxygen absorption and self-crosslinking, leading to insufficient key properties such as film hardness and water resistance; second, a large amount of acetone needs to be added to assist in viscosity reduction, and even with subsequent vacuum distillation to remove it, there are still problems such as strong residual odor and complex process flow. In summary, the industry urgently needs a short-oil-content urethane oil aqueous dispersion that combines ultra-low VOCs (volatile organic compounds), solvent-free operation, storage stability, fast drying, high hardness, and excellent water resistance to overcome the multiple technical challenges of existing processes and promote the large-scale application of water-based urethane oils in the coating field. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a short-oil-content urethane oil-water dispersion with excellent storage stability, extremely low VOC content, rapid drying speed, high hardness, excellent water resistance, and no desolventizing process. The raw materials for its preparation, by mass parts, include: 7-20 parts of diglycidyl ether; 10-20 parts unsaturated fatty acids; 0.01~0.04 parts of hypophosphoric acid; Triphenylphosphine 0.03~0.08 parts; 2-3 parts of hydrophilic chain extender; 0.01-2 parts of small molecule diols; 8-20 parts of diisocyanate monomer; 0.03~0.05 parts of dibutyltin dilaurate; 1-2 parts of triethylamine; 50-60 parts deionized water; 0.2 to 2.5 parts of chain extender.

[0006] This invention does not use auxiliary intermediates such as polyester diols and polyethylene glycol monomethyl ethers. Instead, it uses a terminal hydroxyl diol intermediate generated by ring-opening esterification of unsaturated fatty acids and diglycidyl ether as the main structure, which is then incorporated into the main chain of urethane oil via a chain extension reaction with diisocyanate and a chain extender. A large amount of nonpolar C... 18 Unsaturated alkane segments are regularly distributed in a comb-like structure on the side chains of the urethane oil prepolymer, significantly reducing the polarity and intermolecular forces of the system. This results in a substantial decrease in the viscosity of the prepolymer, allowing for smooth emulsification with water without the need for additional co-solvents. The final product is a solvent-free, short-oil-content urethane oil aqueous dispersion with a solid content of 40-45%, a viscosity of 50-300 mPa·s (25℃), and an oil content of 30-40%. The paint film prepared using this dispersion in combination with an aqueous drier exhibits high crosslinking density, fast drying rate, high hardness, and excellent water resistance.

[0007] A second aspect of this invention provides a method for preparing a short-oil-content urethane oil-water dispersion without solvent removal, comprising the following steps: S1. Add diglycidyl ether and unsaturated fatty acids into a reaction vessel, purge with nitrogen and turn on heating and stirring, add hypophosphite and triphenylphosphine, heat to 150℃ and keep the reaction at that temperature until the acid value is less than 3 mg KOH / g, cool to 120℃, turn off the nitrogen, and dehydrate under vacuum for 1 hour, then cool to 40℃ to obtain a terminal hydroxyl diol intermediate containing fatty acid branches. S2. Add the hydrophilic chain extender, small molecule diol and terminal hydroxyl diol intermediate to the reaction vessel, mix thoroughly, add the diisocyanate monomer, and after the reaction no longer exothermics, raise the temperature to 60~80℃ and keep it at 1h. Then add dibutyltin dilaurate and continue to keep it at 60~85℃ until the NCO content no longer decreases, thus obtaining the urethane oil prepolymer. The number average molecular weight of the urethane oil prepolymer is 2000-3500. S3. Cool down to 50°C, add triethylamine dropwise, and continue stirring at this temperature for 30 minutes. S4. Cool down to 40℃, then add deionized water dropwise to allow for complete phase inversion, emulsification, and dilution. S5. Add the chain extender and extend the chain for 30 minutes, then continue to mature for 2 hours to obtain the short-oil-content urethane oil-water dispersion.

[0008] As an implementable example, the diglycidyl ether is one or more of the following: ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,4-cyclohexanediethanol diglycidyl ether, resorcinol diglycidyl ether, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, and polypropylene glycol diglycidyl ether.

[0009] As an feasible example, the unsaturated fatty acid is one or more of the following: linolenic acid oil fatty acid, tung oil fatty acid, soybean oil fatty acid, tall oil fatty acid, and dehydrated castor oil fatty acid.

[0010] As an feasible example, the hydrophilic chain extender is one or more of dimethylolpropionic acid, dimethylolbutyric acid, and sulfonate diol. Further, the hydrophilic chain extender is dimethylolpropionic acid and / or dimethylolbutyric acid. Both dimethylolpropionic acid and dimethylolbutyric acid are carboxyl-containing hydrophilic diol chain extenders, which can introduce stable hydrophilic carboxyl groups into the molecular chain of urethane oil prepolymer, ensuring that the prepolymer can smoothly achieve self-emulsification and dispersion after neutralization. Simultaneously, it can precisely control the hydrophilic / hydrophobic balance and molecular weight distribution of the prepolymer, improving emulsion stability and providing support for the subsequent formation of a dense cross-linked paint film, thus balancing key properties such as water dispersibility, paint film hardness, and water resistance.

[0011] As an implementable example, the small molecule diol is one or more of ethylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,5-pentanediol, 1,4-cyclohexanediol, 2-methyl-1,3-propanediol, diethylene glycol, dipropylene glycol, and trimethylpentanediol.

[0012] As an implementable example, the diisocyanate monomer is one or more selected from TDI (toluene diisocyanate), IPDI (isophorone diisocyanate), H12MDI (hydrogenated phenylmethane diisocyanate), and TMXDI (tetramethylmethylene diisocyanate). More preferably, the diisocyanate monomer is TDI and / or IPDI.

[0013] As an feasible example, the chain extender is one or more of the following: ethylenediamine, isophorone diamine, hydroxyethyl ethylenediamine, m-phenylenediamine, and A-95 sulfonate diamine.

[0014] Beneficial effects (i) This invention, through a comb-shaped structure design, enables nonpolar C 18 Unsaturated alkane segments are regularly distributed on the side chains of the urethane oil prepolymer, significantly reducing the system's polarity and intermolecular forces. The prepolymer viscosity can be directly reduced to a range suitable for water emulsification. No co-solvents or viscosity reducers such as NMP, acetone, or methyl ethyl ketone are needed throughout the process, nor is a subsequent vacuum distillation solvent removal step required, achieving solvent-free synthesis from the source. The resulting urethane oil aqueous dispersion has a VOC content of less than 20 g / L, fully meeting environmental low-VOC requirements. It also shortens the production cycle, reduces energy consumption and equipment investment, making it more suitable for continuous industrial production.

[0015] (II) This invention abandons the traditional glycerol polyol intermediate and uses diglycidyl ether to generate a uniformly structured terminal hydroxyl diol intermediate through ring-opening esterification with unsaturated fatty acids. This avoids the problems of high color number, wide molecular weight distribution, and insufficient chain extension associated with mixtures of monoglycerides, diglycerides, and triglycerides. The prepared urethane oil aqueous dispersion is a milky white-blue liquid with a viscosity controlled at 50-300 mPa·s and a solid content of 40-45%. It does not separate, deteriorate, or thicken after 30 days of storage at 50°C, and its storage stability is significantly better than that of traditional processes, meeting the requirements for long-distance transportation and long-term storage.

[0016] (III) The short-oil-content urethane oil aqueous dispersion prepared by this invention has a stable oil content of 30-40%. When combined with a water-based drier, it can form a highly cross-linked three-dimensional network coating film, which has advantages such as fast drying speed, high hardness, and outstanding water resistance. The measured surface drying time is 15-35 min, the actual drying time is 1.5-2.5 h, the pencil hardness can reach H-2H, the adhesion is grade 0, and the water resistance test shows no bubbling, whitening, or peeling after 240 h. All performance characteristics are significantly better than traditional water-based urethane oils using glycerol ester polyols, which can meet the needs of wood, flooring, metal corrosion protection and other scenarios for high-hardness, fast-drying, and water-resistant coatings.

[0017] (iv) This invention, through precise control of reaction temperature, material ratio, and catalytic system, stabilizes the number-average molecular weight of the urethane oil prepolymer at 2000-3500, with the optimal range being 2000-3000. This ensures that the prepolymer exhibits moderate viscosity and good flowability during water phase inversion, preventing serious issues such as rod climbing, clumping, and emulsification failure. Compared to high molecular weight systems, this invention maintains low viscosity under high solids content, achieving successful emulsification in a single step without the need for extensive water dilution. The product exhibits good consistency in solids content, viscosity, and particle size, significantly improving production stability and finished product yield.

[0018] (V) This invention provides a variety of options for core raw materials such as diglycidyl ether, unsaturated fatty acids, and diisocyanates. The formulation can be flexibly adjusted according to requirements such as hardness, weather resistance, and drying speed. TDI can be used to achieve high hardness and fast drying, while IPDI and H12MDI can be used to improve yellowing resistance. Different fatty acids can also be combined to adjust the crosslinking density and flexibility. At the same time, the entire process has mild reaction conditions and is easy to control, requiring no special equipment. It is suitable for conventional coating resin production lines and can be quickly industrialized, providing a stable and reliable large-scale preparation solution for high-performance waterborne urethane oils. Detailed Implementation

[0019] The technical solution of the present invention will be further described below with reference to specific embodiments, but this should not be construed as a limitation of the present invention. Based on the embodiments of the present invention, those skilled in the art can make several modifications or improvements without departing from the concept of the present invention, but all of these fall within the protection scope of the present invention. Where specific conditions are not specified in the embodiments, they shall be performed under conventional conditions or conditions recommended by the manufacturer. Where the manufacturer of the reagents or instruments used is not specified, the corresponding conventional products can be obtained through commercial purchase. Viscosity testing shall be performed in accordance with GB / T 2794-2013 standard, and the test temperature shall be 25℃.

[0020] Example 1 The first aspect of this example provides a method for preparing a short-oil-content urethane oil-water dispersion without desolventizing, including the following steps: S1. By mass, 8.61 g of 1,4-cyclohexanediethanol diglycidyl ether and 13.92 g of linseed oil fatty acid were added to a reaction vessel. Nitrogen gas was introduced and heating and stirring were started. 0.02 g of hypophosphite and 0.05 g of triphenylphosphine were added. The temperature was raised to 150°C and kept at that temperature until the acid value was 2.0 mg KOH / g. The temperature was lowered to 120°C, the nitrogen gas was turned off, and the mixture was vacuum dehydrated for 1 hour. Then the temperature was lowered to 40°C to obtain a terminal hydroxyl diol intermediate containing fatty acid branches. S2. Add 2.32g of dimethylolbutyric acid, 0.77g of 1,4-butanediol and terminal hydroxyl diol intermediate to the reaction vessel, mix thoroughly, add 11.88g of TDI monomer, and after the reaction stops exothermic, raise the temperature to 60℃ and keep it at that temperature for 1 hour. Then add 0.04g of dibutyltin dilaurate and keep it at 70℃ until the NCO content no longer decreases, thus obtaining the urethane oil prepolymer with a number average molecular weight of 2700. S3. Cool down to 50℃, slowly add 1.44g of triethylamine dropwise under high-speed stirring, and continue stirring at this temperature for 30min. S4. Cool to 40℃, and add 56.00g of deionized water dropwise to allow for sufficient phase inversion, emulsification, and dilution; S5. Add 1.99g of isophorone diamine and allow it to fully extend the chain for 30 minutes. Then continue to mature for 2 hours to obtain a short-oil-content urethane oil-water dispersion.

[0021] The second aspect of this example provides a short-oil-content urethane oil-water dispersion prepared by the above-mentioned method for preparing short-oil-content urethane oil-water dispersion. The product has a milky white and bluish appearance, a theoretical solid content of 42 wt%, a viscosity of 105 mPa·s, an oil content of 33%, and the dispersion shows no change in appearance after being stored at 50°C for 30 days.

[0022] Example 2 The first aspect of this example provides a method for preparing a short-oil-content urethane oil-water dispersion without desolventizing, including the following steps: S1. By mass, 9.28 g of 1,4-cyclohexanediethanol diglycidyl ether and 15.01 g of tall oil fatty acid were added to a reaction vessel. Nitrogen gas was introduced and heating and stirring were started. 0.02 g of hypophosphite and 0.05 g of triphenylphosphine were added. The temperature was raised to 150°C and kept at that temperature until the acid value was 2.3 mg KOH / g. The temperature was lowered to 120°C, the nitrogen gas was turned off, and the mixture was dehydrated under vacuum for 1 hour. Then the temperature was lowered to 40°C to obtain a terminal hydroxyl diol intermediate containing fatty acid branches. S2. Add 2.32g of dimethylolbutyric acid, 0.88g of neopentyl glycol and terminal hydroxyl diol intermediate to the reaction vessel, mix thoroughly and uniformly, then add 15.41g of IPDI monomer. After the reaction stops exothermic, raise the temperature to 80℃ and keep it at that temperature for 1 hour. Then add 0.043g of dibutyltin dilaurate and continue to keep it at 82℃ until the NCO content no longer decreases, thus obtaining the urethane oil prepolymer with a number average molecular weight of 2400. S3. Cool down to 50℃, slowly add 1.55g of triethylamine under high-speed stirring, and continue stirring at this temperature for 30min. S4. Cool to 40℃, and add 54.00g of deionized water dropwise to allow for sufficient phase inversion, emulsification, and dilution; S5. Add 0.85g of ethylenediamine and allow it to fully extend the chain for 30 minutes. Then continue to mature for 2 hours to obtain a short-oil-content urethane oil-water dispersion.

[0023] The second aspect of this example provides a short-oil-content urethane oil-water dispersion prepared by the above-mentioned method for preparing short-oil-content urethane oil-water dispersion. The product has a milky white and bluish appearance, a theoretical solid content of 44 wt%, a viscosity of 170 mPa·s, an oil content of 35%, and the dispersion shows no change in appearance after being stored at 50°C for 30 days.

[0024] Example 3 The first aspect of this example provides a method for preparing a short-oil-content urethane oil-water dispersion without desolventizing, including the following steps: S1. By mass, 7.88 g of resorcinol diglycidyl ether and 16.64 g of soybean oil fatty acids were added to a reaction vessel. Nitrogen gas was introduced and heating and stirring were started. 0.02 g of hypophosphite and 0.04 g of triphenylphosphine were added. The temperature was raised to 150°C and kept at that temperature until the acid value was 2.7 mg KOH / g. The temperature was lowered to 120°C, the nitrogen gas was turned off, and the mixture was vacuum dehydrated for 1 hour. Then the temperature was lowered to 40°C to obtain a terminal hydroxyl diol intermediate containing fatty acid branches. S2. Add 2.14g of dimethylolpropionic acid, 0.74g of 1,3-propanediol and terminal hydroxyl diol intermediate to the reaction vessel, mix thoroughly and uniformly, then add 15.81g of IPDI monomer. After the reaction stops exothermic, raise the temperature to 80℃ and keep it at that temperature for 1 hour. Then add 0.043g of dibutyltin dilaurate and continue to keep it at 80℃ until the NCO content no longer decreases, thus obtaining the urethane oil prepolymer with a number average molecular weight of 2800. S3. Cool down to 50℃, slowly add 1.53g of triethylamine under high-speed stirring, and continue stirring at this temperature for 30min. S4. Cool to 40℃, and add 54.00g of deionized water dropwise to allow for sufficient phase inversion, emulsification, and dilution; S5. Add 0.81g of ethylenediamine and allow it to fully extend the chain for 30 minutes. Then continue to mature for 2 hours to obtain a short-oil-content urethane oil-water dispersion.

[0025] The second aspect of this example provides a short-oil-content urethane oil-water dispersion prepared by the above-mentioned method for preparing short-oil-content urethane oil-water dispersion. The product has a milky white and bluish appearance, a theoretical solid content of 44 wt%, a viscosity of 220 mPa·s, an oil content of 37%, and the dispersion shows no change in appearance after being stored at 50°C for 30 days.

[0026] Example 4 The first aspect of this example provides a method for preparing a short-oil-content urethane oil-water dispersion without desolventizing, including the following steps: S1. According to mass, 9.50g of bisphenol A diglycidyl ether and 13.21g of linseed oil fatty acid were added to a reaction vessel, nitrogen gas was introduced and heating and stirring were turned on, 0.02g of hypophosphite and 0.04g of triphenylphosphine were added, the temperature was raised to 150℃ and kept at the temperature until the acid value was 2.2mgKOH / g, the temperature was lowered to 120℃, the nitrogen gas was turned off, and the mixture was vacuum dehydrated for 1 hour and then cooled to 40℃ to obtain the terminal hydroxyl diol intermediate containing fatty acid branches. S2. Add 2.20g of dimethylolpropionic acid, 0.82g of neopentyl glycol and terminal hydroxyl diol intermediate to the reaction vessel, mix thoroughly, add 14.27g of IPDI monomer, and after the reaction stops exothermic, raise the temperature to 80℃ and keep it at that temperature for 1 hour. Then add 0.040g of dibutyltin dilaurate and keep it at 85℃ until the NCO content no longer decreases, thus obtaining the urethane oil prepolymer with a number average molecular weight of 2500. S3. Cool down to 50℃, slowly add 1.58g of triethylamine dropwise under high-speed stirring, and continue stirring at this temperature for 30min. S4. Cool to 40℃, and add 57.00g of deionized water dropwise to allow for sufficient phase inversion, emulsification, and dilution; S5. Add 0.69g of ethylenediamine and allow it to fully extend the chain for 30 minutes. Then continue to mature for 2 hours to obtain a short-oil-content urethane oil-water dispersion.

[0027] The second aspect of this example provides a short-oil-content urethane oil-water dispersion prepared by the above-mentioned method for preparing short-oil-content urethane oil-water dispersion. The product has a milky white and bluish appearance, a theoretical solid content of 40.5 wt%, a viscosity of 87 mPa·s, an oil content of 32%, and the dispersion shows no change in appearance after being stored at 50°C for 30 days.

[0028] Example 5 The first aspect of this example provides a method for preparing a short-oil-content urethane oil-water dispersion without desolventizing, including the following steps: S1. By weight, 8.71 g of 1,4-butanediol diglycidyl ether and 18.04 g of tung oil fatty acid were added to a reaction vessel. Nitrogen gas was introduced and heating and stirring were started. 0.03 g of hypophosphite and 0.06 g of triphenylphosphine were added. The temperature was raised to 150°C and kept at that temperature until the acid value was 1.8 mg KOH / g. The temperature was lowered to 120°C, the nitrogen gas was turned off, and the mixture was vacuum dehydrated for 1 hour. Then the temperature was lowered to 40°C to obtain the terminal hydroxyl diol intermediate containing fatty acid branches. S2. Add 2.44g of dimethylolbutyric acid, 1.41g of neopentyl glycol and terminal hydroxyl diol intermediate to the reaction vessel, mix thoroughly and uniformly, then add 13.81g of TDI monomer. After the reaction stops exothermic, raise the temperature to 60℃ and keep it at that temperature for 1 hour. Then add 0.045g of dibutyltin dilaurate and continue to keep it at 70℃ until the NCO content no longer decreases. The urethane oil prepolymer is thus obtained. The number average molecular weight of the urethane oil prepolymer is 2600. S3. Cool down to 50℃, slowly add 1.58g of triethylamine dropwise under high-speed stirring, and continue stirring at this temperature for 30min. S4. Cool to 40℃, and add 53.00g of deionized water dropwise to allow for sufficient phase inversion, emulsification, and dilution; S5. Add 0.68g of ethylenediamine and allow it to fully extend the chain for 30 minutes. Then continue to mature for 2 hours to obtain a short-oil-content urethane oil-water dispersion.

[0029] The second aspect of this example provides a short-oil-content urethane oil-water dispersion prepared by the above-mentioned method for preparing short-oil-content urethane oil-water dispersion. The product has a milky white and bluish appearance, a theoretical solid content of 45 wt%, a viscosity of 120 mPa·s, an oil content of 39%, and the dispersion shows no change in appearance after being stored at 50°C for 30 days.

[0030] Example 6 The first aspect of this example provides a method for preparing a short-oil-content urethane oil-water dispersion without desolventizing, including the following steps: S1. By mass, 7.37 g of 1,3-propanediol diglycidyl ether and 17.69 g of tung oil fatty acid were added to a reaction vessel. Nitrogen gas was introduced and heating and stirring were started. 0.03 g of hypophosphite and 0.05 g of triphenylphosphine were added. The temperature was raised to 150°C and kept at that temperature until the acid value was 1.5 mg KOH / g. The temperature was lowered to 120°C, the nitrogen gas was turned off, and the mixture was vacuum dehydrated for 1 hour. Then the temperature was lowered to 40°C to obtain the terminal hydroxyl diol intermediate containing fatty acid branches. S2. Add 2.34g of dimethylolbutyric acid, 1.79g of 1,4-cyclohexanediol and terminal hydroxyl diol intermediate to the reaction vessel, mix thoroughly, add 13.46g of TDI monomer, and after the reaction stops exothermic, raise the temperature to 60℃ and keep it at that temperature for 1 hour. Then add 0.042g of dibutyltin dilaurate and keep it at 70℃ until the NCO content no longer decreases, thus obtaining the urethane oil prepolymer with a number average molecular weight of 2400. S3. Cool down to 50℃, slowly add 1.52g of triethylamine under high-speed stirring, and continue stirring at this temperature for 30min. S4. Cool to 40℃, and add 54.00g of deionized water dropwise to allow for sufficient phase inversion, emulsification, and dilution; S5. Add 2.05g of isophorone diamine and allow it to fully extend the chain for 30 minutes. Then continue to mature for 2 hours to obtain a short-oil-content urethane oil-water dispersion.

[0031] The second aspect of this example provides a short-oil-content urethane oil-water dispersion prepared by the above-mentioned method for preparing short-oil-content urethane oil-water dispersion. The product has a milky white and bluish appearance, a theoretical solid content of 44 wt%, a viscosity of 102 mPa·s, an oil content of 40%, and the dispersion shows no change in appearance after being stored at 50°C for 30 days.

[0032] Example 7 The first aspect of this example provides a method for preparing a short-oil-content urethane oil-water dispersion without desolventizing, including the following steps: S1. By weight, 15.98g of 207 epoxy reactive diluent (polypropylene glycol diglycidyl ether) and 12.68g of dehydrated castor oil fatty acids were added to a reaction vessel. Nitrogen gas was introduced and heating and stirring were started. 0.03g of hypophosphite and 0.06g of triphenylphosphine were added. The temperature was raised to 150℃ and kept at that temperature until the acid value was 2.8mgKOH / g. The temperature was lowered to 120℃, the nitrogen gas was turned off, and the mixture was vacuum dehydrated for 1 hour. Then the temperature was lowered to 40℃ to obtain a terminal hydroxyl diol intermediate containing fatty acid branches. S2. Add 2.22g of dimethylolbutyric acid, 0.08g of neopentyl glycol and terminal hydroxyl diol intermediate to the reaction vessel, mix thoroughly and uniformly, then add 9.23g of TDI monomer. After the reaction stops exothermic, raise the temperature to 60℃ and keep it at that temperature for 1 hour. Then add 0.040g of dibutyltin dilaurate and continue to keep it at 70℃ until the NCO content no longer decreases, thus obtaining the urethane oil prepolymer with a number average molecular weight of 2800. S3. Cool down to 50℃, slowly add 1.44g of triethylamine dropwise under high-speed stirring, and continue stirring at this temperature for 30min. S4. Cool to 40℃, and add 56.00g of deionized water dropwise to allow for sufficient phase inversion, emulsification, and dilution; S5. Add 1.95g of isophorone diamine and allow it to fully extend the chain for 30 minutes. Then continue to mature for 2 hours to obtain a short-oil-content urethane oil-water dispersion.

[0033] The second aspect of this example provides a short-oil-content urethane oil-water dispersion prepared by the above-mentioned method for preparing short-oil-content urethane oil-water dispersion. The product has a milky white and bluish appearance, a theoretical solid content of 42 wt%, a viscosity of 232 mPa·s, an oil content of 30%, and the dispersion shows no change in appearance after being stored at 50°C for 30 days.

[0034] Example 8 The first aspect of this example provides a method for preparing a short-oil-content urethane oil-water dispersion without desolventizing, including the following steps: S1. By weight, 14.58 g of 215 epoxy reactive diluent (polyethylene glycol diglycidyl ether) and 14.26 g of tall oil fatty acid were added to the reaction vessel. Nitrogen gas was introduced and heating and stirring were started. 0.03 g of hypophosphite and 0.06 g of triphenylphosphine were added. The temperature was raised to 150°C and kept at that temperature until the acid value was 2.8 mg KOH / g. The temperature was lowered to 120°C, the nitrogen gas was turned off, and the mixture was vacuum dehydrated for 1 hour. Then the temperature was lowered to 40°C to obtain the terminal hydroxyl diol intermediate containing fatty acid branches. S2. Add 2.29g of dimethylolbutyric acid, 0.25g of neopentyl glycol and terminal hydroxyl diol intermediate to the reaction vessel, mix thoroughly and uniformly, then add 10.28g of TDI monomer. After the reaction stops exothermic, raise the temperature to 60℃ and keep it at that temperature for 1 hour. Then add 0.041g of dibutyltin dilaurate and continue to keep it at 70℃ until the NCO content no longer decreases, thus obtaining the urethane oil prepolymer with a number average molecular weight of 2600. S3. Cool down to 50℃, slowly add 1.48g of triethylamine dropwise under high-speed stirring, and continue stirring at this temperature for 30min. S4. Cool to 40℃, and add 56.00g of deionized water dropwise to allow for sufficient phase inversion, emulsification, and dilution; S5. Add 0.71g of ethylenediamine and allow it to fully extend the chain for 30 minutes. Then continue to mature for 2 hours to obtain a short-oil-content urethane oil-water dispersion.

[0035] The second aspect of this example provides a short-oil-content urethane oil-water dispersion prepared by the above-mentioned method for preparing short-oil-content urethane oil-water dispersion. The product has a milky white and bluish appearance, a theoretical solid content of 42 wt%, a viscosity of 208 mPa·s, an oil content of 34%, and the dispersion shows no change in appearance after being stored at 50°C for 30 days.

[0036] Comparative Example 1 The first aspect of this example provides a method for preparing a short-oil-content urethane oil-water dispersion without desolventizing, including the following steps: S1. By mass, 7.88 g of resorcinol diglycidyl ether and 16.64 g of soybean oil fatty acids were added to a reaction vessel. Nitrogen gas was introduced and heating and stirring were started. 0.02 g of hypophosphite and 0.04 g of triphenylphosphine were added. The temperature was raised to 150°C and kept at that temperature until the acid value was 2.6 mg KOH / g. The temperature was lowered to 120°C, the nitrogen gas was turned off, and the mixture was vacuum dehydrated for 1 hour. Then the temperature was lowered to 40°C to obtain a terminal hydroxyl diol intermediate containing fatty acid branches. S2. Add 2.14g of dimethylolpropionic acid, 0.74g of 1,3-propanediol and terminal hydroxyl diol intermediate to the reaction vessel, mix thoroughly and uniformly, then add 15.81g of IPDI monomer. After the reaction stops exothermic, raise the temperature to 80℃ and keep it at that temperature for 1 hour. Then add 0.043g of dibutyltin dilaurate and continue to keep it at 80℃ until the NCO content no longer decreases, thus obtaining the urethane oil prepolymer with a number average molecular weight of 3800. S3. Cool down to 50℃, slowly add 1.53g of triethylamine under high-speed stirring, and continue stirring at this temperature for 30min. S4. Cool down to 40℃ and add 56.00g of deionized water to carry out sufficient phase inversion and emulsification. During the phase inversion process, the viscosity is very high, the rod climbs severely and clumps, and a lot of foam appears, ultimately resulting in emulsification failure.

[0037] Comparative Example 2 The first aspect of this example provides a method for preparing a short-oil-content urethane oil-water dispersion without desolventizing, including the following steps: S1. By mass, 7.88 g of resorcinol diglycidyl ether and 16.64 g of soybean oil fatty acids were added to a reaction vessel. Nitrogen gas was introduced and heating and stirring were started. 0.02 g of hypophosphite and 0.04 g of triphenylphosphine were added. The temperature was raised to 150°C and kept at that temperature until the acid value was 2.7 mg KOH / g. The temperature was lowered to 120°C, the nitrogen gas was turned off, and the mixture was vacuum dehydrated for 1 hour. Then the temperature was lowered to 40°C to obtain a terminal hydroxyl diol intermediate containing fatty acid branches. S2. Add 2.14g of dimethylolpropionic acid, 0.88g of 1,3-propanediol and terminal hydroxyl diol intermediate to the reaction vessel, mix thoroughly, add 15.67g of IPDI monomer, and after the reaction stops exothermic, raise the temperature to 80℃ and keep it at that temperature for 1 hour. Then add 0.043g of dibutyltin dilaurate and continue to keep it at 80℃ until the NCO content no longer decreases, thus obtaining the urethane oil prepolymer with a number average molecular weight of 3300. S3. Cool down to 50℃, slowly add 1.53g of triethylamine under high-speed stirring, and continue stirring at this temperature for 30min. S4. Cool down to 40℃, add 50.00g of deionized water dropwise to carry out sufficient phase inversion and emulsification. During the phase inversion process, the viscosity is very high and the emulsion does not have fluidity. Add 25g of deionized water to continue dilution. S5. Add 0.48g of ethylenediamine and allow it to fully extend the chain for 30 minutes. Then continue to mature for 2 hours to obtain a short-oil-content urethane oil-water dispersion.

[0038] The second aspect of this example provides a short-oil-content urethane oil-water dispersion prepared by the above-mentioned method for preparing short-oil-content urethane oil-water dispersion. The product has a milky white and bluish appearance, a theoretical solid content of 23 wt%, a viscosity of 650 mPa·s, and an oil content of 37%.

[0039] Comparative Example 3 The first aspect of this example provides a method for preparing a short-oil-content urethane oil-water dispersion without desolventizing, including the following steps: S1. By mass, 17.53g of monolinolenic acid glyceride (containing ≥60% monoglyceride diol, 20-35% diglyceride, and 1-10% triglyceride) and 2.22g of dimethylolbutyric acid and 4.43g of neopentyl glycol are thoroughly mixed. Stirring and heating are then started. When the temperature reaches 40°C, 15.97g of TDI monomer is added. After the reaction stops exothermic, the temperature is raised to 60°C and held for 1 hour. Then, 0.04g of dibutyltin dilaurate is added, and the temperature is held at 70°C until the NCO content reaches the target value. The urethane oil prepolymer has a theoretical number-average molecular weight of 2700. S2. Cool down to 50℃, slowly add 1.43g of triethylamine dropwise under high-speed stirring, and continue stirring at this temperature for 30min. S3. Cool to 40℃, and add 56.00g of deionized water dropwise to allow for sufficient phase inversion, emulsification, and dilution; S4. Add 1.99g of isophorone diamine and allow it to fully extend the chain for 30 minutes. Then continue to mature for 2 hours to obtain a short-oil-content urethane oil-water dispersion.

[0040] The second aspect of this example provides a short-oil-content urethane oil-water dispersion prepared by the above-mentioned method for preparing short-oil-content urethane oil-water dispersion. The product has a milky white appearance, a theoretical solid content of 42 wt%, a viscosity of 1500 mPa·s, and an oil content of 33%. The dispersion separates into layers after being stored at 50°C for 7 days.

[0041] Comparative analysis of the examples with Comparative Examples 1 and 2 shows that when the number-average molecular weight of the urethane oil prepolymer is above 3000, the emulsification phase inversion process becomes difficult, even leading to emulsification failure. Even if emulsification is successful, the prepared urethane oil aqueous dispersion has excessively high viscosity or low solid content. However, when the number-average molecular weight of the prepolymer is 2000-3000, emulsification proceeds normally, and the prepared urethane oil aqueous dispersion has a solid content of 40-45% and a viscosity range of 50-300 mPa·s.

[0042] Comparative analysis with Comparative Example 3 showed that the aqueous dispersion of urethane oil prepared by the mixture of monolinolenic acid glycerides had no blue luster, high emulsion viscosity, and separated into layers after 7 days of storage at 50°C. In contrast, the aqueous dispersion of urethane oil prepared by the present invention was a thin, bluish-white liquid with no change after 30 days of storage at 50°C, demonstrating better storage stability.

[0043] Performance Evaluation Performance testing method: The urethane oil aqueous dispersions obtained in Examples 1-8 and Comparative Example 3 were combined with an aqueous drier and a substrate wetting agent to prepare a varnish. The coating properties after drying at room temperature (about 25°C) for 7 days are shown in Table 1.

[0044] The water-based drier used was ADDITOL 4940N, with a dosage of 2.0% of the solids of the urethane oil-water dispersion. The substrate wetting agent was Tego 4100, with a dosage of 0.4% of the total amount of varnish.

[0045] Varnish film appearance: visual inspection.

[0046] Drying performance test: Refer to GB / T 1728-1979, test environment temperature 25℃.

[0047] Pencil hardness: Refer to GB / T 6739-2006.

[0048] Adhesion: GB / T 1720-1988.

[0049] Water resistance: Refer to GB / T 1733-1993 and observe whether bubbling occurs after 240 hours.

[0050] Table 1

[0051] The performance test data in Table 1 shows the following results: (1) The varnish films of Examples 1 to 8 are all clear and without haze, but the varnish of Comparative Example 3 has a slight haze.

[0052] (2) The oil content of Comparative Example 3 and Example 1 is the same at 33%, but the drying speed, hardness and water resistance of Example 1 are significantly better.

[0053] (3) The VOC content of the urethane oil aqueous dispersion prepared by the present invention is less than 20 g / L, and no other solvents or co-solvents are added, resulting in extremely low VOC content.

Claims

1. A short-oil-content urethane oil-water dispersion that does not require desolventizing, characterized in that, The raw materials for preparation, by mass parts, include: 7-20 parts of diglycidyl ether; 10-20 parts unsaturated fatty acids; 0.01~0.04 parts of hypophosphoric acid; Triphenylphosphine 0.03~0.08 parts; 2-3 parts of hydrophilic chain extender; 0.01-2 parts of small molecule diols; 8-20 parts of diisocyanate monomer; 0.03~0.05 parts of dibutyltin dilaurate; 1-2 parts of triethylamine; 50-60 parts deionized water; 0.2 to 2.5 parts of chain extender.

2. The short-oil-content urethane oil-water dispersion according to claim 1, characterized in that, The diglycidyl ether is one or more of the following: ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,4-cyclohexanediethanol diglycidyl ether, resorcinol diglycidyl ether, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, and polypropylene glycol diglycidyl ether.

3. The short-oil-content urethane oil-water dispersion according to claim 1, characterized in that, The unsaturated fatty acids mentioned are one or more of the following: linseed oil fatty acids, tung oil fatty acids, soybean oil fatty acids, tall oil fatty acids, and dehydrated castor oil fatty acids.

4. The short-oil-content urethane oil-water dispersion according to claim 1, characterized in that, The hydrophilic chain extender is one or more of dimethylolpropionic acid, dimethylolbutyric acid, and sulfonate diol.

5. The short-oil-content urethane oil-water dispersion according to claim 1, characterized in that, The small molecule diol is one or more of ethylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,5-pentanediol, 1,4-cyclohexanediol, 2-methyl-1,3-propanediol, diethylene glycol, dipropylene glycol, and trimethylpentanediol.

6. The short-oil-content urethane oil-water dispersion according to claim 1, characterized in that, The diisocyanate monomer is one or more of TDI, IPDI, H12MDI, and TMXDI.

7. The short-oil-content urethane oil-water dispersion according to claim 1, characterized in that, The chain extender is one or more of the following: ethylenediamine, isophorone diamine, hydroxyethyl ethylenediamine, m-phenylenediamine, and A-95 sulfonate diamine.

8. A method for preparing a short-oil-content urethane oil-water dispersion according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Add diglycidyl ether and unsaturated fatty acids into a reaction vessel, purge with nitrogen and turn on heating and stirring, add hypophosphite and triphenylphosphine, heat to 150℃ and keep the reaction at that temperature until the acid value is less than 3 mg KOH / g, cool to 120℃, turn off the nitrogen, and dehydrate under vacuum for 1 hour, then cool to 40℃ to obtain a terminal hydroxyl diol intermediate containing fatty acid branches. S2. Add hydrophilic chain extender, small molecule diol and terminal hydroxyl diol intermediate to the reaction vessel, mix thoroughly and uniformly, add diisocyanate monomer, and after the reaction no longer exothermic, raise the temperature to 60~80℃ and keep it at 1h. Then add dibutyltin dilaurate and continue to keep it at 60~85℃ until the NCO content no longer decreases, thus obtaining urethane oil prepolymer. S3. Cool down to 50°C, add triethylamine dropwise, and continue stirring at this temperature for 30 minutes. S4. Cool down to 40℃, then add deionized water dropwise to allow for complete phase inversion, emulsification, and dilution. S5. Add the chain extender and extend the chain for 30 minutes, then continue to mature for 2 hours to obtain the short-oil-content urethane oil-water dispersion.

9. The preparation method according to claim 8, characterized in that, The number-average molecular weight of the urethane oil prepolymer is 2000-3500.

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