A polyurethane resin for nail polish and a preparation process thereof

Abstract

The application relates to the technical field of polyurethane, and discloses a polyurethane resin for nail polish and a preparation process thereof. The polyurethane resin for nail polish is obtained by reacting dihydric alcohol, isophorone diisocyanate, diol chain extender, vinyl chain extender and dibutyl tin dilaurate. 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, water dispersibility and storage stability. The active alkenyl group is introduced into the side chain of the polyurethane resin, the double bond conversion rate of the resin is higher, the photocuring speed is faster, the photocuring reaction of the resin is accelerated, and the curing time is reduced. Meanwhile, the resin curing product has good tensile strength and elongation at break, and has good practical application in water-based photocuring nail polish and the like.

Description

Technical Field

[0001] This invention relates to the field of polyurethane technology, specifically to a polyurethane resin for nail polish gel and its preparation process. Background Technology

[0002] Waterborne polyurethane uses water as a solvent, making it environmentally friendly and possessing excellent film-forming properties. It is widely used in nail polish, adhesives, coatings, and other fields. Waterborne polyurethane is typically formulated using 2,2-dimethylolpropionic acid as a waterborne chain extender and neutralizing agents such as triethylamine. Adding hydroxyethyl methacrylate or similar substances for end-capping during the polymerization reaction yields UV-curable alkenyl-terminated polyurethanes with high reactivity and fast curing speed. However, in practical applications, hydroxyethyl methacrylate-terminated polyurethanes only contain alkenyl groups at the end positions, resulting in fewer photocurable crosslinking sites, poor curing effect, and lower mechanical and other properties of the cured resin.

[0003] Developing high-performance chain extenders for polyurethane is a research hotspot. Chinese patent CN112500772B discloses a betaine cationic waterborne polyurethane antibacterial coating and its preparation method. Using polyester diol, diisocyanate, betaine chain extender, small molecule chain extender, cationic hydrophilic chain extender, glacial acetic acid, etc. as raw materials, the prepared waterborne polyurethane emulsion has good antibacterial properties. However, this waterborne polyurethane does not have a UV curing effect, which is not conducive to the practical application of polyurethane in UV-cured nail polish and other products. Summary of the Invention

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

[0005] The technical solution of this invention: A preparation process for polyurethane resin for nail polish gel:

[0006] (1) Use a solvent and an ethyl N,N-dihydroxyethyl-3-aminopropionate (structural formula: ) in a molar ratio of 1:(1.2-1.4) to form ethyl N,N-dihydroxyethyl-3-aminopropionate. The bromoalkylene was added to a reaction vessel and stirred at 50-65°C for 24-36 hours. The mixture was then distilled under reduced pressure, and the product was recrystallized from an aqueous ethanol solution to obtain the intermediate. The structural formula of the bromoalkylene is [insert structural formula here]. n is any integer from 1 to 4. The reaction formula is:

[0007] .

[0008] (2) adding the aqueous sodium hydroxide solution, ethanol and the intermediate into a reaction container, stirring and refluxing condensation at 90-100 DEG C for 3-4 h, removing ethanol under reduced pressure, adding saturated sodium chloride solution, extracting with ethyl acetate, removing the ethyl acetate extract under reduced pressure, and recrystallizing the product in an aqueous ethanol solution to obtain the vinyl chain extender.

[0009] .

[0010] (3) under a nitrogen atmosphere, adding the vacuum-dried dihydric alcohol and isophorone diisocyanate into a reaction container, reacting at 70-75 DEG C for 2-2.5 h, then adding acetone, the diol chain extender, the vinyl chain extender and dibutyl tin dilaurate, reacting at 40-45 DEG C for 1-1.5 h, adding water, stirring and dispersing, and removing acetone under reduced pressure to obtain the polyurethane resin for nail polish.

[0011] wherein the solvent is ethanol or acetonitrile.

[0012] wherein the concentration of the aqueous sodium hydroxide solution is (2.5-3) mol / L.

[0013] wherein the molar ratio of the dihydric alcohol, isophorone diisocyanate, diol chain extender, vinyl chain extender and dibutyl tin dilaurate is 1:(2.6-2.8):(0.7-1):(0.4-0.6):(0.012-0.016).

[0014] wherein the dihydric alcohol is one of polyethylene glycol and polytetrahydrofuran ether diol.

[0015] wherein the diol chain extender is one of 1,4-butanediol and 1,6-hexanediol.

[0016] The polyurethane resin for nail polish is prepared by subjecting N,N-dihydroxyethyl-3-aminopropionic acid ethyl ester and 3-bromopropylene to quaternary ammonium reaction, hydrolyzing the ester group to obtain the vinyl chain extender, and then subjecting the vinyl chain extender, dihydric alcohol and isophorone diisocyanate to polymerization reaction.

[0017] The application introduces active alkenyl groups into the side chain of the polyurethane resin through the vinyl chain extender, so that the double bond conversion rate of the resin is higher, the photocuring speed is faster, the photocuring reaction of the resin is accelerated, and the curing time is reduced. After introducing the alkenyl group into the side chain of the polyurethane resin, the photocuring crosslinking sites and the crosslinking degree of the molecular chain of the resin are increased, so that the mechanical properties of the resin cured product are improved, and higher tensile strength and elongation at break are exhibited. The prepared polyurethane resin has good practical application in water-based photocuring nail polish glue and the like. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved in the present application more clear and explicit, the present application will be further described in detail below in combination with embodiments. However, this should not be understood as limiting the scope of the present application to the following examples. Without departing from the method idea of the present application, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present application.

[0019] According to the method of the journal “New Chemical Materials”, August 2010, Volume 38, No. 8, document “Synthesis of a new epoxy-terminated hyperbranched poly(amine-ester)”, N,N-dihydroxyethyl-3-aminopropionic acid ethyl ester is prepared. 0.1 mol of diethanolamine, 5 mL of ethanol are added to a reaction bottle, nitrogen is introduced, 0.12 mol of ethyl acrylate is added dropwise at room temperature, the temperature is increased to 35℃, and stirring is performed for 4 h, and then ethanol and ethyl acrylate are removed by distillation under reduced pressure, and then drying is performed, to obtain N,N-dihydroxyethyl-3-aminopropionic acid ethyl ester.

[0020] Example 1

[0021] (1) 250 mL of ethanol, 50 mmol of N,N-dihydroxyethyl-3-aminopropionic acid ethyl ester, and 60 mmol of 3-bromopropylene are added to a reaction container, and stirring is performed at 50℃ for 36 h, and then distillation is performed under reduced pressure, and then the product is recrystallized in an 80% (volume fraction) ethanol aqueous solution, to obtain an intermediate. The structural formula is .

[0022] (2) 70 mL of a 3 mol / L sodium hydroxide aqueous solution, 60 mL of ethanol, and 30 g of the intermediate are added to a reaction container, and stirring and condensation reflux are performed at 100℃ for 3 h, and then ethanol is removed by distillation under reduced pressure, and then a saturated sodium chloride solution is added, and then extraction is performed with ethyl acetate, and then the ethyl acetate extract is distilled under reduced pressure, and then the product is recrystallized in a 60% (volume fraction) ethanol aqueous solution, to obtain a vinyl chain extender. The structural formula is .

[0023] (3) In a nitrogen atmosphere, 100 mmol of vacuum-dried polyethylene glycol 2000, 280 mmol of isophorone diisocyanate were added to a reaction vessel, 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, 1.6 mmol of dibutyltin dilaurate were added, reacted at 40°C for 1.5 h, 250 mL of water was added, stirred and dispersed, and the acetone was removed by distillation under reduced pressure to obtain a polyurethane resin for a mastic.

[0024] Example 2

[0025] (1) 200 mL of acetonitrile, 50 mmol of N,N-dihydroxyethyl-3-aminopropionic acid ethyl ester, and 70 mmol of 6-bromo-1-hexene were added to a reaction vessel, stirred and reacted at 65°C for 24 h, distilled under reduced pressure, and the product was recrystallized from an 80% by volume ethanol aqueous solution to obtain an intermediate.

[0026] (2) 80 mL of a 2.5 mol / L sodium hydroxide aqueous solution, 60 mL of ethanol, and 30 g of the intermediate were added to a reaction vessel, stirred and refluxed at 90°C for 4 h, distilled under reduced pressure to remove the ethanol, a saturated sodium chloride solution was added, extracted with ethyl acetate, the ethyl acetate extract was distilled under reduced pressure, and the product was recrystallized from a 60% by volume ethanol aqueous solution to obtain a vinyl chain extender. The structural formula is .

[0027] (3) In a nitrogen atmosphere, 100 mmol of vacuum-dried polytetramethylene ether glycol 2000, 270 mmol of isophorone diisocyanate were added to a reaction vessel, 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, 1.3 mmol of dibutyltin dilaurate were added, reacted at 45°C for 1 h, 220 mL of water was added, stirred and dispersed, and the acetone was removed by distillation under reduced pressure to obtain a polyurethane resin for a mastic.

[0028] Example 3

[0029] (1) In a nitrogen atmosphere, 100 mmol of vacuum-dried polyethylene glycol 2000, 270 mmol of isophorone diisocyanate were added to a reaction vessel, 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), 1.4 mmol of dibutyltin dilaurate were added, reacted at 40°C for 1.5 h, 250 mL of water was added, stirred and dispersed, and the acetone was removed by distillation under reduced pressure to obtain a polyurethane resin for a mastic.

[0030] Example 4

[0031] (1) 100 mmol of vacuum-dried polytetramethylene ether glycol 2000, 260 mmol of isophorone diisocyanate were added to a reaction vessel under a nitrogen atmosphere, 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 from Example 1), 1.2 mmol of dibutyltin dilaurate were added, reacted at 40°C for 1.5 h, 230 mL of water was added, dispersed by stirring, acetone was removed by distillation under reduced pressure, and dispersed by shearing to obtain a polyurethane resin for a lacquer thinner.

[0032] Comparative Example 1

[0033] (1) 100 mmol of vacuum-dried polytetramethylene ether glycol 2000, 260 mmol of isophorone diisocyanate were added to a reaction vessel under a nitrogen atmosphere, 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 from Example 1), 1.2 mmol of dibutyltin dilaurate were added, reacted at 40°C for 1.5 h, 230 mL of water was added, dispersed by stirring, acetone was removed by distillation under reduced pressure, and dispersed by shearing to obtain a polyurethane resin for a lacquer thinner.

[0034] Comparative Example 2

[0035] (1) 100 mmol of vacuum-dried polytetramethylene ether glycol 2000, 260 mmol of isophorone diisocyanate were added to a reaction vessel under a nitrogen atmosphere, 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 from Example 1), 1.2 mmol of dibutyltin dilaurate were added, reacted at 40°C for 1.5 h, 230 mL of water was added, dispersed by stirring, acetone was removed by distillation under reduced pressure, and dispersed by shearing to obtain a polyurethane resin for a lacquer thinner. Comparative Example 3

[0036] (1) 100 mmol of vacuum-dried polytetramethylene ether glycol 2000, 260 mmol of isophorone diisocyanate were added to a reaction vessel under a nitrogen atmosphere, 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 from Example 1), 1.2 mmol of dibutyltin dilaurate were added, reacted at 40°C for 1.5 h, 230 mL of water was added, dispersed by stirring, acetone was removed by distillation under reduced pressure, and dispersed by shearing to obtain a polyurethane resin for a lacquer thinner.

[0037]

[0038] ​The storage stability of the polyurethane resin was tested according to the method specified in GB / T 6753.3-1986.

[0039] Double bond conversion rate test. The specific method is: 28 g of active diluent butyl acrylate and 8.4 g of photoinitiator 1173 are added to the polyurethane resin prepared in each example and the comparative example. After stirring, the resin is dropped into two clean NaCl salt pieces, dried, and then irradiated and cured in a 30 W ultraviolet light curing machine for 40 s, with the light irradiation distance controlled at 12 cm. The resin cured product is subjected to infrared spectrum analysis to determine the conversion rate of the alkenyl double bond. Double bond conversion rate = (A0-A t ) / A0x 100%; A0is the peak area integral at 1635 cm -1 in the infrared spectrum of the resin before ultraviolet irradiation. A t is the peak area integral at 1635 cm -1 in the infrared spectrum of the resin cured product after 40 s of ultraviolet irradiation.

[0040] The resin cured product is dried, and the tensile properties of the resin cured product are tested according to the method of GB / T 528-2009. The test results are as shown in Table 1.

[0041] Table 1 Performance test of polyurethane resin

[0042] Storage stability (months) Double bond conversion (%) 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

[0043] After testing, the storage stability of the polyurethane resin of Examples 1-4 reaches 7-12 months, mainly because the addition of the vinyl chain extender containing the hydrophilic betaine group (composed of quaternary ammonium salt cations and carboxylate anions) makes the polyurethane have better hydrophilicity and water dispersibility, and can be uniformly dispersed in water, so that 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 introducing alkenyl groups into the polyurethane resin side chain, the photocuring crosslinking sites and molecular chain crosslinking degree of the resin are increased, which is conducive to improving the mechanical properties of the resin cured product, and higher tensile strength and elongation at break are exhibited.

[0044] Compared with Example 1, Comparative Example 1 only added 1,4-butanediol chain extender, the prepared polyurethane resin does not contain hydrophilic betaine groups, resulting in poor water dispersibility of the polyurethane, and poor storage stability of the emulsion. And the polyurethane does not contain alkenyl groups, which cannot be cured by ultraviolet light, and cannot be made into resin cured product. Comparative Example 2 uses intermediate as chain extender, the obtained polyurethane resin only contains hydrophilic quaternary ammonium salt cations, and the water dispersibility of the polyurethane and the storage stability of the emulsion are lower than those of Example 1. Comparative Example 3 uses conventional 2,2-dimethylol propionic acid as water-based chain extender, the obtained polyurethane resin has good water dispersibility and storage stability, but the water-based polyurethane needs to add additional neutralizing agent triethylamine to neutralize the carboxyl group. At the same time, hydroxyethyl methacrylate is added for end capping, and the obtained polyurethane only contains photo-curable alkenyl groups at the end, and the double bond conversion rate is low, which is not conducive to improving the photo-curing speed and reducing the photo-curing time, and the resin has fewer photo-curing crosslinking sites and weaker molecular chain crosslinking degree, resulting in lower tensile strength and elongation at break of the resin cured product than those of Example 1.

[0045] The specific embodiments are only an explanation of the present application, which is not a limitation of the present application, and those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A process for preparing a polyurethane resin for use in a top coat, characterized by, The preparation process is as follows: vacuum dewatered dihydric alcohol and isophorone diisocyanate are added into a reaction container in a nitrogen atmosphere, a first reaction is carried out, then acetone, dihydric alcohol chain extender, vinyl chain extender and dibutyl tin dilaurate are added, a second reaction is carried out, water is added, stirring and dispersion are carried out, acetone is removed by distillation under reduced pressure, and a polyurethane resin for lacquer is obtained; The structural formula of the ethylene-based chain extender is: n is any integer from 1 to 4; The preparation process of the vinyl chain extender is as follows: (1) a solvent, N,N-dihydroxyethyl-3-aminopropionic acid ethyl ester with a molar ratio of 1:(1.2-1.4) and bromoalkyl alkene are added into a reaction container, a reaction is carried out, the product is recrystallized in an ethanol aqueous solution by distillation under reduced pressure, and an intermediate is obtained; The bromoalkyl ene has a structural formula of n is any integer from 1 to 4; (2) sodium hydroxide aqueous solution, ethanol and the intermediate are added into a reaction container, a reaction is carried out, ethanol is removed by distillation under reduced pressure, saturated sodium chloride solution is added, extraction is carried out with ethyl acetate, the ethyl acetate extract is distilled under reduced pressure, and the product is recrystallized in an ethanol aqueous solution, and a vinyl chain extender is obtained; The dihydric alcohol chain extender is one of 1,4-butanediol and 1,6-hexanediol.

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

3. The process for preparing polyurethane resin for nail gel according to claim 2, characterized in that, The dihydric alcohol is one of polyethylene glycol and polytetrahydrofuran ether diol.

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

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

6. The process for the preparation of polyurethane resin for nail gel according to claim 1, characterized in that, The temperature of the reaction in (1) is 50-65 DEG C, and the time is 24-36 h.

7. The process for preparing polyurethane resin for nail gel according to claim 1, characterized in that, The concentration of the sodium hydroxide aqueous solution in (2) is (2.5-3) mol / L.

8. The process for preparing polyurethane resin for nail gel according to claim 1, characterized in that, The temperature of the reaction in (2) is 90-100 DEG C, and the time is 3-4 h.

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