Polyurethane resin for nail polish gel and preparation process of polyurethane resin

Abstract

The invention relates to the technical field of polyurethane, and discloses a polyurethane resin for a nail polish gel and a preparation process thereof, dihydric alcohol, isophorone diisocyanate, a diol chain extender, a vinyl chain extender, dibutyltin dilaurate and the like are reacted to obtain the polyurethane resin for the nail polish gel. The vinyl chain extender contains a hydrophilic betaine group which is introduced into a molecular chain of polyurethane, so that the polyurethane has better hydrophilicity, water dispersibility and storage stability. The active alkenyl is introduced into the side chain of the polyurethane resin, so that the double bond conversion rate of the resin is higher, the photocuring speed is higher, the photocuring reaction of the resin is accelerated, and the curing time is shortened. And meanwhile, the cured resin has good tensile strength and elongation at break, and has good practical application in the aspects of water-based light-cured nail polish gel and the like.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane, in particular to a polyurethane resin for nail polish and a preparation process thereof. Background Art

[0002] Waterborne polyurethane uses water as solvent, is green and environmentally friendly, has excellent film-forming properties, and is widely used in nail polish, adhesives, coatings and other fields. Waterborne polyurethane is usually made with 2,2-dihydroxymethylpropionic acid and other water-based chain extenders, and neutralizers such as triethylamine are added. During the polymerization reaction, hydroxyethyl methacrylate and other esters are added for end-capping to obtain UV-curable terminal olefin polyurethane, which has high reaction activity and fast curing speed. However, in actual application, the polyurethane capped with hydroxyethyl methacrylate only contains olefin groups at the end position, has fewer photocuring cross-linking sites, and has poor curing effect. The mechanical properties of the obtained resin cured product are low.

[0003] The development of high-performance polyurethane chain extenders is a research hotspot. Chinese patent CN112500772B discloses a betaine cationic waterborne polyurethane antibacterial coating and its preparation method, which uses polyester diol, diisocyanate, betaine chain extender, small molecule chain extender, cationic hydrophilic chain extender, glacial acetic acid and the like as raw materials to prepare a waterborne polyurethane emulsion with good antibacterial properties, but the waterborne polyurethane does not have a UV curing effect, which is not conducive to the practical application of polyurethane in light-cured nail polish and the like. Summary of the invention

[0004] The invention solves the following technical problems: It solves the problems of poor water dispersibility and low mechanical properties of polyurethane resin used in nail polish.

[0005] The technical solution of the present invention: a preparation process of polyurethane resin for nail polish: (1) Solvent and N,N-dihydroxyethyl-3-aminopropionic acid ethyl ester (structural formula: ), add the brominated alkylene to the reaction vessel, stir and react at 50-65°C for 24-36h, distill under reduced pressure, and recrystallize the product in ethanol aqueous solution to obtain an intermediate. The structural formula of brominated alkylene is , n is any integer from 1 to 4. The reaction formula is: .

[0006] (2) Add sodium hydroxide aqueous solution, ethanol and intermediate into a reaction vessel, stir and condense under reflux at 90-100°C for 3-4h, remove ethanol by vacuum distillation, add saturated sodium chloride solution, extract with ethyl acetate, vacuum distill the ethyl acetate extract, and recrystallize the product in ethanol aqueous solution to obtain a vinyl chain extender. The reaction formula is: .

[0007] (3) In a nitrogen atmosphere, add the vacuum-dehydrated diol and isophorone diisocyanate into a reaction vessel, react at 70-75°C for 2-2.5 hours, then add acetone, diol chain extender, vinyl chain extender, and dibutyltin dilaurate, react at 40-45°C for 1-1.5 hours, add water, stir and disperse, and remove acetone by reduced pressure distillation to obtain a polyurethane resin for nail polish.

[0008] Wherein, the solvent is ethanol or acetonitrile.

[0009] Among them, the concentration of the sodium hydroxide aqueous solution is (2.5-3) mol / L.

[0010] The molar ratio of diol, isophorone diisocyanate, diol chain extender, vinyl chain extender and dibutyltin dilaurate is 1:(2.6-2.8):(0.7-1):(0.4-0.6):(0.012-0.016).

[0011] Wherein, the diol is one of polyethylene glycol and polytetramethylene glycol.

[0012] The diol chain extender is one of 1,4-butanediol and 1,6-hexanediol.

[0013] The beneficial technical effect of the present invention is as follows: the present invention carries out quaternization reaction on N,N-dihydroxyethyl-3-aminopropionic acid ethyl ester and 3-bromopropylene, and then carries out ester group hydrolysis to obtain a vinyl chain extender, and then carries out polymerization reaction with diol, isophorone diisocyanate, etc. to obtain a polyurethane resin for nail polish. The vinyl chain extender contains a hydrophilic betaine group, which is introduced into the molecular chain of the polyurethane, so that the polyurethane has better hydrophilicity and water dispersibility, can be evenly dispersed in water, and the prepared water-based resin emulsion has good storage stability.

[0014] The present invention introduces active alkenyl groups into the side chains of polyurethane resins through vinyl chain extenders, so that the double bond conversion rate of the resin is higher and the light curing speed is faster, which is beneficial to accelerate the light curing reaction of the resin and reduce the curing time. After the alkenyl groups are introduced into the side chains of the polyurethane resins, the light curing cross-linking sites and molecular chain cross-linking degree of the resin are increased, which is beneficial to improve the mechanical properties of the resin cured product and show higher tensile strength and elongation at break. The prepared polyurethane resin has good practical applications in water-based light-curing nail polish and the like. DETAILED DESCRIPTION

[0015] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application is further described in detail below in conjunction with the embodiments. However, this should not be understood as the scope of the present application being limited to the following examples. Without departing from the above-mentioned method ideas of the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0016] According to the method of the journal "Chemical New Materials", Vol. 38, No. 8, August 2010, the document "Synthesis of a New Epoxy-Terminated Hyperbranched Poly(Amine-Ester)". Add 0.1 mol of diethanolamine and 5 mL of ethanol to the reaction bottle, pass nitrogen, add 0.12 mol of ethyl acrylate dropwise at room temperature, heat to 35°C, stir and react for 4 hours, remove ethanol and ethyl acrylate by vacuum distillation, and dry to obtain N,N-dihydroxyethyl-3-aminopropionic acid ethyl ester.

[0017] Example 1 (1) Add 250 mL of ethanol, 50 mmol of N,N-dihydroxyethyl-3-aminopropionic acid ethyl ester, and 60 mmol of 3-bromopropylene to a reaction vessel, stir and react at 50°C for 36 hours, and distill under reduced pressure. The product is recrystallized in an ethanol aqueous solution with a volume fraction of 80% to obtain an intermediate. The structural formula is .

[0018] (2) Add 70 mL of 3 mol / L sodium hydroxide aqueous solution, 60 mL of ethanol, and 30 g of the intermediate into a reaction vessel, stir and condense at 100°C for 3 h, remove ethanol by vacuum distillation, add saturated sodium chloride solution, extract with ethyl acetate, vacuum distill the ethyl acetate extract, and recrystallize the product in 60% by volume ethanol aqueous solution to obtain a vinyl chain extender. The structural formula is: .

[0019] (3) In a nitrogen atmosphere, 100 mmol of vacuum-dehydrated polyethylene glycol 2000 and 280 mmol of isophorone diisocyanate were added to a reaction vessel and reacted at 70°C for 2.5 h. Then, 80 mL of acetone, 100 mmol of 1,4-butanediol, 40 mmol of a vinyl chain extender, and 1.6 mmol of dibutyltin dilaurate were added and reacted at 40°C for 1.5 h. 250 mL of water was added and stirred for dispersion. The acetone was removed by vacuum distillation to obtain a polyurethane resin for nail polish.

[0020] Example 2 (1) Add 200 mL of acetonitrile, 50 mmol of ethyl N,N-dihydroxyethyl-3-aminopropionate, and 70 mmol of 6-bromo-1-hexene into a reaction vessel, stir and react at 65°C for 24 h, and distill under reduced pressure. The product is recrystallized in an ethanol aqueous solution with a volume fraction of 80% to obtain an intermediate.

[0021] (2) Add 80 mL of 2.5 mol / L sodium hydroxide aqueous solution, 60 mL of ethanol, and 30 g of the intermediate into a reaction vessel, stir and condense at 90°C for 4 h, remove ethanol by vacuum distillation, add saturated sodium chloride solution, extract with ethyl acetate, vacuum distill the ethyl acetate extract, and recrystallize the product in 60% by volume ethanol aqueous solution to obtain a vinyl chain extender. The structural formula is .

[0022] (3) In a nitrogen atmosphere, 100 mmol of vacuum-dehydrated polytetramethylene glycol 2000 and 270 mmol of isophorone diisocyanate were added to a reaction vessel and reacted at 70°C for 2.5 h. Then, 70 mL of acetone, 85 mmol of 1,6-hexanediol, 50 mmol of a vinyl chain extender, and 1.3 mmol of dibutyltin dilaurate were added and reacted at 45°C for 1 h. 220 mL of water was added and stirred for dispersion. The acetone was removed by vacuum distillation to obtain a polyurethane resin for nail polish.

[0023] Example 3 (1) In a nitrogen atmosphere, 100 mmol of vacuum-dehydrated polyethylene glycol 2000 and 270 mmol of isophorone diisocyanate were added to a reaction container and reacted at 75° C. for 2 h. Then, 80 mL of acetone, 85 mmol of 1,4-butanediol, 45 mmol of a vinyl chain extender (prepared in Example 1) and 1.4 mmol of dibutyltin dilaurate were added and reacted at 40° C. for 1.5 h. 250 mL of water was added and stirred for dispersion. The acetone was removed by vacuum distillation to obtain a polyurethane resin for nail polish.

[0024] Example 4 (1) In a nitrogen atmosphere, 100 mmol of vacuum-dehydrated polytetramethylene glycol 2000 and 260 mmol of isophorone diisocyanate were added to a reaction container and reacted at 75° C. for 2 h. Then, 70 mL of acetone, 70 mmol of 1,4-butanediol, 60 mmol of a vinyl chain extender (prepared in Example 1) and 1.2 mmol of dibutyltin dilaurate were added and reacted at 40° C. for 1.5 h. 230 mL of water was added and stirred for dispersion. The acetone was removed by vacuum distillation and shear dispersion was performed to obtain a polyurethane resin for nail polish.

[0025] Comparative Example 1 (1) In a nitrogen atmosphere, 100 mmol of vacuum-dehydrated polyethylene glycol 2000 and 280 mmol of isophorone diisocyanate were added to a reaction vessel and reacted at 70°C for 2.5 h. Then, 80 mL of acetone, 140 mmol of 1,4-butanediol and 1.6 mmol of dibutyltin dilaurate were added and reacted at 40°C for 1.5 h. 250 mL of water was added and stirred for dispersion. The acetone was removed by vacuum distillation and shear dispersion was performed to obtain a polyurethane resin for nail polish.

[0026] Comparative Example 2 (1) In a nitrogen atmosphere, 100 mmol of vacuum-dehydrated polyethylene glycol 2000 and 280 mmol of isophorone diisocyanate were added to a reaction vessel and reacted at 70°C for 2.5 h. Then, 80 mL of acetone, 100 mmol of 1,4-butanediol, and 40 mmol of the intermediate (structural formula: , prepared by Example 1), 1.6 mmol dibutyltin dilaurate, react at 40°C for 1.5h, add 250mL water, stir and disperse, remove acetone by vacuum distillation, shear and disperse, and obtain a polyurethane resin for nail polish.

[0027] Comparative Example 3 (1) In a nitrogen atmosphere, 100 mmol of vacuum-dehydrated polyethylene glycol 2000 and 280 mmol of isophorone diisocyanate were added to a reaction vessel and reacted at 70°C for 2.5 h. Then, 80 mL of acetone, 100 mmol of 1,4-butanediol, 40 mmol of 2,2-dihydroxymethylpropionic acid and 1.6 mmol of dibutyltin dilaurate were added and reacted at 40°C for 1.5 h. 50 mmol of hydroxyethyl methacrylate was added and reacted for 1 h. 250 mL of water and 40 mmol of a neutralizing agent, triethylamine, were added and stirred for dispersion. The acetone was removed by vacuum distillation and the mixture was dispersed by shearing to obtain a polyurethane resin for nail polish.

[0028] The storage stability of polyurethane resin was tested according to the method specified in GB / T 6753.3-1986.

[0029] Double bond conversion test. The specific method is: add 28g of active diluent butyl acrylate and 8.4g of photoinitiator 1173 to the polyurethane resin for nail polish prepared in each embodiment and comparative example. After stirring, drop the resin into 2 clean NaCl salt tablets, dry it, and cure it in a 30W ultraviolet light curing machine for 40 seconds, and control the light distance to be 12cm. The cured resin is subjected to infrared spectroscopy analysis to determine the conversion rate of olefinic double bonds. Double bond conversion rate = (A 0 -A t ) / A 0 ×100%; A 0The infrared spectrum of the resin at 1635 cm -1 The peak area integration at A t The infrared spectrum of the cured resin at 1635 cm after UV irradiation for 40 seconds. -1 The peak area integration at .

[0030] The cured resin was dried and the tensile properties of the cured resin were tested according to the method of GB / T 528-2009. The test results are shown in Table 1.

[0031] Table 1 Polyurethane resin performance test Storage stability (months) Double bond conversion rate (%) Tensile strength (MPa) Elongation at break (%) Example 1 ≧8 73.3 21.2 378.4 Example 2 ≧11 77.1 29.7 345.0 Example 3 ≧12 81.8 35.0 281.5 Example 4 ≧12 80.5 38.6 232.4 Comparative Example 1 ≧1 - - - Comparative Example 2 ≧5 73.0 21.6 375.8 Comparative Example 3 ≧7 64.2 13.7 217.3 After testing, the storage stability of the polyurethane resin of Examples 1-4 reaches 7-12 months, mainly because the added vinyl chain extender contains a hydrophilic betaine group (composed of a quaternary ammonium salt cation and a carboxylic acid anion), which makes the polyurethane have better hydrophilicity and water dispersibility, and can be evenly dispersed in water. The prepared water-based resin emulsion has good storage stability. At the same time, the polyurethane resin side chain contains active alkenyl groups, the double bond conversion rate is higher, and the photocuring speed is faster, which is conducive to accelerating the photocuring reaction of the resin and reducing the curing time. And after the alkenyl groups are introduced into the side chains of the polyurethane resin, the photocuring cross-linking sites and molecular chain cross-linking degree of the resin are increased, which is conducive to improving the mechanical properties of the resin cured product, showing higher tensile strength and elongation at break.

[0032] Compared with Example 1, Comparative Example 1 only adds 1,4-butanediol chain extender, and the prepared polyurethane resin does not contain hydrophilic betaine groups, resulting in poor water dispersibility of polyurethane and poor storage stability of emulsion. In addition, polyurethane does not contain alkenyl groups, UV curing cannot occur, and resin cured products cannot be made. Comparative Example 2 uses the intermediate as a chain extender, and the obtained polyurethane resin contains only hydrophilic quaternary ammonium salt cations, and the water dispersibility of polyurethane and the storage stability of the emulsion are lower than those of Example 1. Comparative Example 3 uses conventional 2,2-dimethylolpropionic acid as an aqueous chain extender, and the obtained polyurethane resin has good water dispersibility and storage stability, but the aqueous polyurethane needs to be additionally added with a neutralizing agent triethylamine to neutralize the carboxyl group. At the same time, hydroxyethyl methacrylate is added for end-capping, and the obtained polyurethane contains only photocurable alkenyl groups at the end positions, and the double bond conversion rate is low, which is not conducive to increasing the photocuring speed and reducing the photocuring time, and the resin has fewer photocuring cross-linking sites, and the molecular chain cross-linking degree is weak, resulting in the tensile strength and elongation at break of the resin cured product being lower than that of Example 1.

[0033] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but such modifications are protected by patent law as long as they are within the scope of the claims of the present application.

Claims

1. A process for preparing polyurethane resin for nail polish, characterized in that: The preparation process comprises: adding vacuum dehydrated diol and isophorone diisocyanate into a reaction container in a nitrogen atmosphere to carry out a first reaction, then adding acetone, a diol chain extender, a vinyl chain extender, and dibutyltin dilaurate to carry out a second reaction, adding water, stirring and dispersing, and removing acetone by reduced pressure distillation to obtain a polyurethane resin for nail polish glue; The structural formula of the vinyl chain extender is: , n is any integer from 1 to 4.

2. The process for preparing the polyurethane resin for nail polish according to claim 1, characterized in that: The molar ratio of the diol, isophorone diisocyanate, diol chain extender, vinyl chain extender and dibutyltin dilaurate is 1:(2.6-2.8):(0.7-1):(0.4-0.6):(0.012-0.016).

3. The process for preparing the polyurethane resin for nail polish according to claim 2, characterized in that: The diol is one of polyethylene glycol and polytetramethylene glycol; the diol chain extender is one of 1,4-butanediol and 1,6-hexanediol.

4. The process for preparing the polyurethane resin for nail polish according to claim 1, characterized in that: The temperature of the first reaction is 70-75°C and the time is 2-2.5h, and the temperature of the second reaction is 40-45°C and the time is 1-1.5h.

5. The process for preparing the polyurethane resin for nail polish according to claim 2, characterized in that: The preparation process of the vinyl chain extender is: (1) adding a solvent, ethyl N,N-dihydroxyethyl-3-aminopropionate and bromoalkylene in a molar ratio of 1:(1.2-1.4) to a reaction vessel, performing a reaction, performing vacuum distillation, and recrystallizing the product in an ethanol aqueous solution to obtain an intermediate; The structural formula of the bromoalkylene is , n is any integer from 1 to 4; (2) A sodium hydroxide aqueous solution, ethanol and the intermediate are added to a reaction vessel to react, the ethanol is removed by distillation under reduced pressure, a saturated sodium chloride solution is added, extraction is performed with ethyl acetate, the ethyl acetate extract is distilled under reduced pressure, and the product is recrystallized in an ethanol aqueous solution to obtain a vinyl chain extender.

6. The process for preparing the polyurethane resin for nail polish according to claim 5, characterized in that: The solvent in (1) is ethanol or acetonitrile.

7. The process for preparing the polyurethane resin for nail polish according to claim 5, characterized in that: The reaction temperature in (1) is 50-65°C and the reaction time is 24-36h.

8. The process for preparing polyurethane resin for nail polish according to claim 5, characterized in that: The concentration of the sodium hydroxide aqueous solution in (2) is (2.5-3) mol / L.

9. The process for preparing the polyurethane resin for nail polish according to claim 5, characterized in that: The reaction temperature in (2) is 90-100°C and the reaction time is 3-4h.

10. A polyurethane resin for nail polish obtained by the preparation process according to any one of claims 1 to 9.

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