Preparation method of waterborne polyurethane coating with intrinsic flame retardation and self-repairing
By introducing disulfide bonds and borate ester structures into waterborne polyurethane coatings, a semi-interpenetrating network structure with both self-healing and flame-retardant properties is formed, solving the problems of poor flame-retardant properties and insufficient self-healing ability of waterborne polyurethane coatings, and realizing the self-healing and flame-retardant effects of the coatings.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGDONG TIANYIN IND CO LTD
- Filing Date
- 2026-05-09
- Publication Date
- 2026-06-12
Smart Images
Figure CN122188471A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of coating technology, specifically relating to a method for preparing a waterborne polyurethane coating that combines intrinsic flame retardancy and self-healing properties. Background Technology
[0002] Currently, waterborne polyurethanes contain a large number of hydrophilic groups, resulting in poor solvent and water resistance, and are prone to swelling or hydrolysis. Therefore, they are often modified with polyacrylates to produce composite materials. These composite materials combine the excellent properties of the two polymers, giving the material good heat resistance, low-temperature resistance, and chemical corrosion resistance, among other superior properties. However, during long-term use, due to the influence of external environments such as heat and mechanical forces, cracks or damage inevitably occur, affecting service life and safety. Self-healing materials, as intelligent biomimetic materials, can repair internal cracks in a short time, thereby extending service life, eliminating safety hazards, and reducing costs. They are widely used in military, aerospace, and medical fields where manual repair is difficult and lifespan requirements are high. However, research has found that most self-healing materials struggle to simultaneously achieve both high repair efficiency and low repair temperature. Compared to other self-healing materials, disulfide bond-type self-healing materials contain weaker dynamic covalent bonds, exhibiting excellent characteristics such as mild reaction conditions and no need for external stimulation. However, their weak repair ability limits their application.
[0003] Due to its inherent molecular structure, polyurethane is extremely flammable, which greatly limits its application prospects. Currently, flame retardants for polyurethane are mainly classified into additive types. Among them, the additive flame retardant method has advantages such as simple composite material preparation process and a wide variety of flame retardants to choose from, making it the most economical, effective, and convenient flame retardant method. However, additive flame retardants are prone to migration and volatilization, have poor flame retardant durability, poor compatibility with the matrix, and can easily cause a decline in the mechanical properties of the material, thus limiting its application. Summary of the Invention
[0004] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, the main objective of this invention is to provide a waterborne polyurethane coating that combines intrinsic flame retardancy and self-healing properties, aiming to solve the problems of poor flame retardancy and inability to repair existing coatings. This coating can achieve self-repair of cracks, fractures, or scratches, thereby improving its service life.
[0005] The objective of this invention is achieved through the following technical solution: The preparation method provided by this invention introduces disulfide bonds during the preparation process, followed by the introduction of a borate ester structure. The hydroxyl group of the propyl group in the di(3-dihydroxypropyl)disulfide reacts with boric acid to form a borate ester bond. The self-healing effect of the borate ester bond, combined with the disulfide bond, synergistically enhances the material's self-healing ability. Simultaneously, the introduction of boron endows the material with intrinsic flame-retardant properties. Then, acrylic monomers are added during the reaction process for polymerization modification, synthesizing a series of SWPUAs with self-healing semi-interpenetrating network structures, ultimately forming a waterborne polyurethane / acrylic coating that combines intrinsic flame retardancy and self-healing properties.
[0006] A method for preparing a waterborne polyurethane coating that combines intrinsic flame retardancy and self-healing properties includes the following steps: (1) Isocyanate, 2,2-dimethylolbutyric acid, polyol and dibutyltin dilaurate are mixed and prepolymerized under stirring to obtain polyurethane prepolymer dispersion; (2) Add bis(3-dihydroxypropyl) disulfide to the polyurethane prepolymer dispersion in step (1) to carry out a prepolymerization reaction to obtain the prepolymer; (3) Reduce the temperature of the prepolymer from step (2) to 40-60℃, then add boric acid and catalyst, and continue the reaction for 2-4 hours to obtain a prepolymer dispersion; (4) Lower the temperature of the prepolymer dispersion in step (3) to room temperature (unless otherwise specified, room temperature refers to room temperature 25°C), then add triethylamine TEA to the prepolymer dispersion and stir evenly, then add acrylic monomer and distilled water, stir at high speed to emulsify and disperse, and obtain a preemulsion. (5) Add an initiator to the pre-emulsion in step (4) and stir the reaction at 70~90℃ to obtain an acrylic-polyurethane waterborne coating containing borate esters and disulfide bonds, which is an intrinsic flame retardant and self-healing waterborne acrylic-polyurethane coating.
[0007] The synthesis process of the waterborne acrylic-polyurethane coating in this invention is as follows: In some specific embodiments, the waterborne acrylic-polyurethane coating comprises, by weight, 1-20 parts isocyanate, 1-10 parts 2,2-dimethylolbutyric acid, 10-30 parts polyol, 0.003-0.015 parts dibutyltin dilaurate, 10-20 parts di(3-dihydroxypropyl)disulfide, 1-10 parts boric acid, 0.01-0.1 parts catalyst, 5-15 parts triethylamine, 1-10 parts acrylic monomer, 30-50 parts distilled water, and 0.01-1 parts initiator.
[0008] In some specific embodiments, the conditions for the prepolymerization reaction in step (1) are: the prepolymerization reaction temperature is 70-90℃ and the time is 4-6h.
[0009] In some specific embodiments, the isocyanate mentioned in step (1) is at least one of toluene diisocyanate, isophorone diisocyanate, or diphenylmethane diisocyanate. In some specific embodiments, the polyol in step (1) is at least one of polycarbonate diol (PCDL-1000), polyacrylol (PPG-1000), and polyacrylol (PPG-2000).
[0010] In some specific embodiments, the process conditions for the prepolymerization reaction in step (2) are: the prepolymerization reaction temperature is 70-90℃ and the time is 3-7h.
[0011] In some specific embodiments, the catalyst in step (3) is at least one of a tetrachloroaluminate complex or trifluoroacetic anhydride.
[0012] In some specific embodiments, the acrylic monomer in step (4) is at least one of methyl acrylate and butyl acrylate.
[0013] In some specific embodiments, the initiator in step (5) is at least one of azobisisobutyronitrile or potassium persulfate.
[0014] Compared with the prior art, the present invention has at least the following advantages: 1) The preparation method of the present invention involves preparing a waterborne polyurethane / polyacrylate composite material (WPUA) by modifying polyurethane with acrylic acid. During the preparation process, disulfide bonds are introduced, and the hydroxyl groups of the propyl group in the di(3-dihydroxypropyl) disulfide are used to generate borate bonds with boric acid. Then, acrylic monomers are added during the reaction process for modification, and finally a waterborne polyurethane / acrylic coating with both flame retardancy and self-healing properties is formed.
[0015] 2) The waterborne polyurethane emulsion of this invention firstly introduces acrylates into the waterborne polyurethane to form a core-shell structure or interpenetrating network (IPN) structure, fully combining the excellent properties of waterborne polyurethane and acrylic resin. Secondly, by introducing disulfide bonds, which have lower energy than the weak covalent bonds of carbon-carbon and carbon-hydrogen bonds and possess dynamic reversibility, repair is achieved through chemical bond recombination between sulfur atoms of adjacent disulfide bonds. The reaction conditions are mild, requiring no external stimulation, and the disulfide bonds can also be reversibly rearranged in the presence of light, heat, and reducing agents, endowing the waterborne acrylic-polyurethane coating with self-healing function. Thirdly, by introducing borate ester bonds, which are also reversible chemical bonds with pH-sensitive characteristics, the application scenarios are broadened. Furthermore, under conditions such as heat, they can also undergo dynamic exchange, enabling them to heal, remodel, and recycle. Synergistically working with disulfide bonds, this further enhances the material's self-healing performance. Moreover, the introduction of boron into the system provides flame retardant effects, forming an intrinsically flame-retardant material. Attached Figure Description
[0016] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below.
[0017] Figure 1 The image shows the FTIR-ATR characterization of the waterborne acrylic-polyurethane coating provided in Example 1 of this invention. Detailed Implementation
[0018] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The following embodiments are merely descriptive and not limiting, and should not be construed as limiting the scope of protection of the present invention.
[0019] When a quantity, concentration, or other value or parameter is described as a range, preferred range, or preferred upper and lower limits, it should be understood that it is equivalent to specifically disclosing any range by combining any pair of upper or preferred values with any lower or preferred values, regardless of whether the range is specifically disclosed. Unless otherwise stated, the numerical range values listed herein include the endpoints of the range and all integers and fractions within that range.
[0020] Unless otherwise stated, all percentages, parts, ratios, etc. in this document are by weight.
[0021] The materials, methods, and embodiments described herein are exemplary and should not be construed as limiting unless otherwise stated.
[0022] Unless otherwise specified, all raw materials, production equipment or devices, and testing devices mentioned in this application can be obtained through commercial purchases. Example 1
[0023] This embodiment provides a method for preparing a waterborne polyurethane coating that combines intrinsic flame retardancy and self-healing properties, comprising the following steps: (1) Mix 5g IPDI, 2g 2,2-dimethylolbutyric acid, 10g PPG-2000 and 0.003g dibutyltin dilaurate, and react for 4h at 70℃ to obtain a polyurethane prepolymer dispersion; (2) At 70°C, 10g of bis(3-dihydroxypropyl) disulfide was added to the polyurethane prepolymer dispersion, and the reaction was continued for 3h to successfully obtain the prepolymer. (3) The temperature of the prepolymer was lowered to 60°C, 1g of boric acid and 0.01g of tetrachloroaluminate complex catalyst were added, and the reaction was continued for 2 hours to obtain the prepolymer dispersion; (4) Lower the temperature of the prepolymer dispersion to room temperature, add 5g TEA to the prepolymer dispersion and stir evenly, then add 1g BA and 30g distilled water, and stir at high speed to emulsify and disperse for 1h to obtain a preemulsion; (5) Add 0.01g of azobisisobutyronitrile initiator to the pre-emulsion and stir the reaction at 70°C for 4h to obtain SWPUA1, an acrylic-polyurethane waterborne coating containing borate ester and disulfide bond, which is an intrinsic flame retardant and self-healing waterborne acrylic-polyurethane coating.
[0024] The prepared emulsion was poured into a silicone mold, defoamed in a vacuum drying oven for 0.5 hours, and dried at room temperature for 12 hours to obtain a water-based acrylic-polyurethane coating that combines flame retardancy and self-healing properties. Example 2
[0025] This embodiment provides a method for preparing a waterborne polyurethane coating that combines intrinsic flame retardancy and self-healing properties, comprising the following steps: (1) Mix 20g TDI, 10g 2,2-dimethylolbutyric acid, 30g PCDL-1000 and 0.015g dibutyltin dilaurate, and react for 6h at 90℃ to obtain a polyurethane prepolymer dispersion; (2) At 90°C, 20g of bis(3-dihydroxypropyl) disulfide was added to the polyurethane prepolymer dispersion, and the reaction was continued for 7h to successfully obtain the prepolymer. (3) The temperature of the prepolymer was lowered to 40°C, 10g of boric acid and 0.1g of trifluoroacetic anhydride catalyst were added, and the reaction was continued for 4 hours to obtain the prepolymer dispersion; (4) Lower the temperature of the prepolymer dispersion to room temperature, add 15g TEA to the polyurethane prepolymer dispersion and stir evenly, then stir and disperse to obtain a preemulsion, then add 10g MA and 50g distilled water, stir at high speed to emulsify and disperse for 3h to obtain a preemulsion. (5) Add 1g of potassium persulfate to the pre-emulsion and stir the reaction at 90°C for 6h to obtain SWPUA2, an acrylic-polyurethane waterborne coating containing borate esters and disulfide bonds, which is an intrinsic flame retardant and self-healing waterborne acrylic-polyurethane coating.
[0026] The prepared emulsion was poured into a silicone mold, defoamed in a vacuum drying oven for 0.5 hours, and dried at room temperature for 12 hours to obtain a water-based acrylic-polyurethane coating that combines flame retardancy and self-healing properties. Example 3
[0027] This embodiment provides a method for preparing a waterborne polyurethane coating that combines intrinsic flame retardancy and self-healing properties, comprising the following steps: (1) Mix 15g IPDI, 10g 2,2-dimethylolbutyric acid, 30g PPG-1000 and 0.01g dibutyltin dilaurate, and react for 5h at 85℃ to obtain a polyurethane prepolymer dispersion; (2) At 85°C, 20g of bis(3-dihydroxypropyl) disulfide was added to the polyurethane prepolymer dispersion, and the reaction was continued for 6h to successfully obtain the prepolymer. (3) The temperature of the prepolymer was lowered to 40°C, 10g of boric acid and 0.1g of trifluoroacetic anhydride catalyst were added, and the reaction was continued for 4 hours to obtain the prepolymer dispersion; (4) Lower the temperature of the prepolymer dispersion to room temperature, add 10 TEA to the polyurethane prepolymer dispersion and stir evenly, then stir and disperse to obtain a preemulsion, then add 4g MA, 5g BA and 50g distilled water, stir at high speed to emulsify and disperse for 3h to obtain a preemulsion. (5) Add 0.1g of potassium persulfate to the pre-emulsion and stir for 5h at 75°C to obtain SWPUA3, an acrylic-polyurethane waterborne coating containing borate esters and disulfide bonds, which is an intrinsic flame retardant and self-healing waterborne acrylic-polyurethane coating.
[0028] The prepared emulsion was poured into a silicone mold, defoamed in a vacuum drying oven for 0.5 hours, and dried at room temperature for 12 hours to obtain a water-based acrylic-polyurethane coating that combines flame retardancy and self-healing properties.
[0029] Comparative Example 1 This comparative example provides a method for preparing an aqueous acrylic-polyurethane coating, which is basically the same as that in Example 2, except that bis(3-dihydroxypropyl) disulfide and borate ester are not introduced, i.e. steps (2) and (3) are omitted. Specifically, it includes the following steps: (1) Mix 20g TDI, 10g 2,2-dimethylolbutyric acid, 30g PCDL-1000 and 0.015g dibutyltin dilaurate, and react for 6h at 90℃ to obtain a polyurethane prepolymer dispersion; (2) Reduce the temperature of the polyurethane prepolymer dispersion to 25°C, add 15g TEA to the polyurethane prepolymer dispersion and stir evenly, then stir and disperse to obtain a preemulsion, then add 10g MA and 50g distilled water, stir at high speed to emulsify and disperse for 3h to obtain a preemulsion. (3) Add 1g of potassium persulfate to the pre-emulsion and stir at 90°C for 6h to obtain waterborne polyurethane coating.
[0030] Comparative Example 2 This comparative example provides a method for preparing an aqueous acrylic-polyurethane coating, which is basically the same as that in Example 2, except that bis(3-dihydroxypropyl) disulfide is not introduced, i.e., step (2) is omitted. Specifically, it includes the following steps: (1) Mix 20g TDI, 10g 2,2-dimethylolbutyric acid, 30g PCDL-1000 and 0.015g dibutyltin dilaurate, and react for 6h at 90℃ to obtain a polyurethane prepolymer dispersion; (2) The temperature of the polyurethane prepolymer dispersion was lowered to 40°C, 10g of boric acid and 0.1g of trifluoroacetic anhydride catalyst were added, and the reaction was continued for 4 hours to obtain the prepolymer dispersion. (3) Reduce the temperature of the prepolymer dispersion to 25°C, add 15g TEA to the polyurethane prepolymer dispersion and stir evenly, then stir and disperse to obtain a preemulsion, then add 10g MA and 50g distilled water, stir at high speed to emulsify and disperse for 3h to obtain a preemulsion. (4) Add 1g of potassium persulfate to the pre-emulsion and stir at 90°C for 6h to obtain an acrylic-polyurethane waterborne coating. The prepared acrylic-polyurethane waterborne coating was poured into a silicone mold, defoamed in a vacuum drying oven for 0.5 h, and dried at room temperature for 12 h to obtain a waterborne acrylic-polyurethane coating.
[0031] Comparative Example 3 This comparative example provides a method for preparing an aqueous acrylic-polyurethane coating, which is basically the same as that in Example 2, except that borate ester is not introduced, i.e., step (3) is omitted. Specifically, it includes the following steps: (1) Mix 20g TDI, 10g 2,2-dimethylolbutyric acid, 30g PCDL-1000 and 0.015g dibutyltin dilaurate, and react for 6h at 90℃ to obtain a polyurethane prepolymer dispersion; (2) At 90°C, 20g of bis(3-dihydroxypropyl) disulfide was added to the polyurethane prepolymer dispersion, and the reaction was continued for 7h to successfully obtain the prepolymer. (3) Reduce the temperature of the prepolymer to 25°C, add 15g TEA to the polyurethane prepolymer dispersion and stir evenly, then stir and disperse to obtain a preemulsion, then add 10g MA and 50g distilled water, stir at high speed to emulsify and disperse for 3h to obtain a preemulsion. (4) Add 1g of potassium persulfate to the pre-emulsion and stir at 90°C for 6h to obtain an acrylic-polyurethane waterborne coating.
[0032] The prepared acrylic-polyurethane waterborne coating was poured into a silicone mold, defoamed in a vacuum drying oven for 0.5 h, and dried at room temperature for 12 h to obtain a waterborne acrylic-polyurethane coating.
[0033] Performance testing: This application uses Example 1 as an example to conduct performance tests on the prepared waterborne acrylic-polyurethane coating that combines intrinsic flame retardancy and self-healing properties, specifically as follows: 1) Structural characterization This test uses Example 1 as an example to characterize the prepared waterborne acrylic-polyurethane coating, which combines flame retardancy and self-healing properties, using FTIR-ATR. The results are as follows: Figure 1 As shown in the figure, the spectral line of this waterborne acrylic-polyurethane coating, which combines flame retardancy and self-healing properties, is at 29130 cm⁻¹. -1 The broad absorption band at 1535 cm⁻¹ is due to the stretching vibrations of the CH₂ and CH₃ groups. -1 and 3317 cm -1 The absorption peak at this point is attributed to the NH tensile and bending vibrations of the urethane group, while the tensile vibration peaks of -COC- and -C=O are located at 1100 cm⁻¹. -1 and 1706 cm -1 The polymer's characteristic peaks of -NCO near 2270 cm⁻¹ and -OH near 3540 cm⁻¹ completely disappeared, indicating that the disulfide bonds had participated in the reaction and were fully introduced. In summary, the preparation method of this application successfully prepared an aqueous acrylic-polyurethane coating containing borate esters and disulfide bonds.
[0034] 2) Flame retardant properties This test examines the oxygen index and flame retardant properties of the waterborne acrylic-polyurethane coatings prepared in Examples 1-3 and Comparative Examples 1-3. The oxygen index was tested according to GB / T 2406-2009, and the flame retardant properties were tested according to UL94 standard. The results are shown in Table 1. Table 1 Flame retardant properties of the waterborne acrylic-polyurethane coatings prepared in each example and comparative example. As shown in Table 1, the introduction of boron significantly improves the flame retardant properties of waterborne acrylic-polyurethane coatings, achieving a V-0 rating and demonstrating excellent intrinsic flame retardant performance.
[0035] 3) Mechanical property testing The mechanical properties of the waterborne acrylic-polyurethane coatings prepared in Examples 1-3 and Comparative Examples 1-3 were tested according to GB / T1040-2006. The tensile test specimens were type 2 dumbbell plates with a thickness of 1.0 mm. The self-healing effect was verified by making a 0.3 mm microcrack in the middle of the type 2 dumbbell plate. The results are shown in Table 2. Table 2 Mechanical properties of the waterborne acrylic-polyurethane coatings prepared in each example and comparative example As can be seen from the data in Table 2, the introduction of disulfide bonds and borate ester bonds results in good self-healing function, good retention of strength and elongation at break, and superior mechanical properties. This may be due to the introduction of more small molecular chains and a more complete interpenetrating network, which leads to better mechanical properties.
[0036] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.
Claims
1. A method for preparing a waterborne polyurethane coating that combines intrinsic flame retardancy and self-healing properties, characterized in that, Includes the following steps: (1) Isocyanate, 2,2-dimethylolbutyric acid, polyol and dibutyltin dilaurate are mixed and prepolymerized under stirring to obtain polyurethane prepolymer dispersion; (2) Add bis(3-dihydroxypropyl) disulfide to the polyurethane prepolymer dispersion in step (1) to carry out a prepolymerization reaction to obtain the prepolymer; (3) Lower the temperature of the prepolymer from step (2) to the reaction temperature, then add boric acid and catalyst, and continue the reaction to obtain a prepolymer dispersion; (4) Lower the temperature of the prepolymer dispersion in step (3) to room temperature, then add triethylamine TEA to the prepolymer dispersion and stir evenly, then add acrylic monomer and distilled water, and stir at high speed to emulsify and disperse to obtain a preemulsion; (5) Add an initiator to the pre-emulsion in step (4) and continue the reaction while stirring to obtain an acrylic-polyurethane waterborne coating containing borate esters and disulfide bonds, which is an intrinsic flame retardant and self-healing waterborne acrylic-polyurethane coating.
2. The method for preparing the waterborne polyurethane coating with intrinsic flame retardancy and self-healing properties according to claim 1, characterized in that, The waterborne acrylic-polyurethane coating comprises, by weight, 1-20 parts isocyanate, 1-10 parts 2,2-dimethylolbutyric acid, 10-30 parts polyol, 0.003-0.015 parts dibutyltin dilaurate, 10-20 parts di(3-dihydroxypropyl)disulfide, 1-10 parts boric acid, 0.01-0.1 parts catalyst, 5-15 parts triethylamine, 1-10 parts acrylic monomer, 30-50 parts distilled water, and 0.01-1 parts initiator.
3. The method for preparing the waterborne polyurethane coating with intrinsic flame retardancy and self-healing properties according to claim 1, characterized in that, The conditions for the prepolymerization reaction in step (1) are: the prepolymerization reaction temperature is 70-90℃ and the time is 4-6h.
4. The method for preparing the waterborne polyurethane coating with intrinsic flame retardancy and self-healing properties according to claim 1, characterized in that, The isocyanate mentioned in step (1) is at least one of toluene diisocyanate, isophorone diisocyanate or diphenylmethane diisocyanate.
5. The method for preparing the waterborne polyurethane coating with intrinsic flame retardancy and self-healing properties according to claim 4, characterized in that, The polyol mentioned in step (1) is at least one of polycarbonate diol, polyacrylol, or polyacrylol.
6. The method for preparing the waterborne polyurethane coating with intrinsic flame retardancy and self-healing properties according to claim 1, characterized in that, The process conditions for the prepolymerization reaction in step (2) are: the prepolymerization reaction temperature is 70-90℃ and the time is 3-7h; the process conditions for the reaction in step (3) are: the temperature is 40-60℃ and the time is 2-4h; the process conditions for the reaction in step (5) are: the temperature is 70-90℃ and the time is 4-6h.
7. The method for preparing the waterborne polyurethane coating with intrinsic flame retardancy and self-healing properties according to claim 1, characterized in that, The catalyst mentioned in step (3) is at least one of tetrachloroaluminate complex or trifluoroacetic anhydride.
8. The method for preparing the waterborne polyurethane coating with intrinsic flame retardancy and self-healing properties according to claim 4, characterized in that, The acrylic monomer mentioned in step (4) is at least one of methyl acrylate and butyl acrylate.
9. The method for preparing the waterborne polyurethane coating with intrinsic flame retardancy and self-healing properties according to claim 1, characterized in that, The initiator mentioned in step (5) is at least one of azobisisobutyronitrile or potassium persulfate.