A sulfonic acid type waterborne polyurethane acrylate resin and preparation method thereof

Abstract

The present invention relates to a sulfonic acid type waterborne polyurethane acrylate resin and a preparation method thereof. The preparation method of the sulfonic acid type waterborne polyurethane acrylate resin comprises the following steps: S1. adding a polymerization inhibitor to a diisocyanate; S2. adding an acrylate end-capping agent to carry out an end-capping reaction; S3. adding a sulfonate polyester polyol and reacting; S4. adding an acrylate end-capping agent and carrying out an end-capping reaction to obtain the sulfonic acid type waterborne polyurethane acrylate resin. The sulfonic acid type waterborne polyurethane acrylate resin prepared by this preparation method can maintain low viscosity at a high solid content (30-40 wt%), has good high and low temperature storage stability, and has minimal sediment at the bottom of the emulsion. Using water as the dispersion medium, the resin is green, safe, and environmentally friendly, making it suitable as a base resin for waterborne coatings. Furthermore, the entire process does not require the addition of organic solvents to reduce viscosity, making the preparation process environmentally friendly and economical.

Description

Technical Field

[0001] The present invention relates to the field of waterborne polyurethane resins, and more particularly to a sulfonic acid type waterborne polyurethane acrylate resin and a preparation method thereof. Background Art

[0002] Traditional organic solvent-based polyurethane resins, due to their high content of volatile organic solvents, have poor environmental performance during use and are extremely susceptible to significant harm to human health, leading to their gradual abandonment by users and the market. At the same time, in light of relevant policy requirements from environmental protection authorities, there is a consensus on strengthening pollution prevention and control in the photocurable resin industry at the source, and developing environmentally friendly waterborne polyurethane resins. Waterborne polyurethane resins use water as a dispersion medium to replace traditional organic solvents. Compared to organic solvent-based resins, they are colorless, odorless, non-toxic, environmentally friendly, and more economical. Waterborne polyurethane resins also offer advantages such as low-temperature resistance, wear resistance, brittleness resistance, high tensile strength, toughness, and good elasticity. They are widely used in industries such as ink printing, electronics, automotive parts, leather, coatings, adhesives, wood processing, and construction.

[0003] The raw materials used to synthesize waterborne polyurethane resins are diverse. Based on the charge properties of the hydrophilic groups, waterborne polyurethane resins can be divided into three categories: anionic, cationic, and nonionic. Anionic waterborne polyurethane resins are the most widely used and have the largest output. However, most anionic waterborne polyurethane resins currently prepared in China have various problems. For example, the viscosity of the PU prepolymer during the synthesis process is relatively high. Before dispersing it in water, it needs to be reduced with an organic solvent. After chain extension, the organic solvent needs to be evaporated and removed. The production process is complex, energy-intensive, and costly. In addition, the removal of the organic solvent is difficult. For example, a Chinese patent entitled "Sulfonate-type UV-curable waterborne polyurethane and its preparation method" is available. During the production process, the prepolymer is excessively cross-linked, resulting in an excessively high molecular weight. After emulsification and dispersion, particles easily agglomerate, resulting in the appearance of heavy component residues at the bottom of the emulsion and poor stability. In order to achieve low viscosity, the solid content of the emulsion is often low, containing a large amount of water, resulting in low equipment utilization and low construction efficiency.

[0004] Therefore, it is necessary to solve the problem that organic solvents need to be added during the preparation of water-based polyurethane resins, and it is difficult to achieve both low viscosity and high solid content. Summary of the Invention

[0005] The primary purpose of the present invention is to overcome the aforementioned problems of existing waterborne polyurethane resins, which require the addition of organic solvents during preparation and struggle to achieve both low viscosity and high solids content. The present invention provides a method for preparing a sulfonic acid-based waterborne polyurethane acrylate resin. The sulfonic acid-based waterborne polyurethane acrylate resin produced by the present invention can maintain low viscosity (less than 125 mPa·s) at a high solids content (30-40 wt%). The entire process of preparing the sulfonic acid-based waterborne polyurethane acrylate resin does not require the addition of organic solvents to reduce viscosity, making the preparation process environmentally friendly and economical. Furthermore, the resulting sulfonic acid-based waterborne polyurethane acrylate resin exhibits excellent or good storage stability. After further dilution (at a solids content of 3%), the emulsion contains only minimal or small amounts of sediment. Furthermore, using water as the dispersion medium, the resin is environmentally friendly, safe, and suitable as a base resin for waterborne coatings.

[0006] A further object of the present invention is to provide a sulfonic acid type waterborne polyurethane acrylate resin.

[0007] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0008] A method for preparing a sulfonic acid type waterborne polyurethane acrylate resin comprises the following steps:

[0009] S1. Adding an inhibitor to the diisocyanate;

[0010] S2. Adding an acrylate capping agent to perform a capping reaction;

[0011] S3. Add sulfonate polyester polyol and react;

[0012] S4 is added acrylate capping agent, capping reaction, to obtain the sulfonic acid type waterborne polyurethane acrylate resin;

[0013] The molar ratio of -NCO of the diisocyanate in step S1 to -OH of the acrylate end-capping agent in step S2 is 1:(0.30-0.60); the acrylate end-capping agent in step S2 is a water-soluble acrylate end-capping agent; and the reaction temperature in step S2 is ≤50°C.

[0014] The inventors of the present invention have discovered through repeated research that at a specific temperature (≤50°C), the reactivity of the two -NCO groups in a diisocyanate molecule differs significantly. When a certain amount of a water-soluble acrylate end-capping agent is used to cap the diisocyanate, the diisocyanate reacts primarily with the acrylate end-capping agent through the more reactive -NCO group, while the less reactive -NCO group participates less in the reaction, resulting in one -NCO group of some diisocyanate molecules being capped. The introduction of a hydrophilic sulfonate polyester polyol prevents excessive polymerization or crosslinking of the diisocyanate and sulfonate polyester polyol, which could lead to excessive viscosity or even gelation. The resulting sulfonic acid-based waterborne polyurethane acrylate resin can maintain a low viscosity (less than 125 mPa·s) at a high solids content (30-40 wt%). The preparation process of this sulfonic acid-based waterborne polyurethane acrylate resin does not require the addition of an organic solvent to reduce viscosity, making the preparation process environmentally friendly and economical. In addition, the prepared sulfonic acid type water-based polyurethane acrylate resin has excellent or good storage stability. After further dilution (when the solid content is 3%), there is only very little or a small amount of sediment at the bottom of the emulsion. Water is used as the dispersion medium, which is green, safe and environmentally friendly, and is suitable as a base resin for water-based coatings.

[0015] If the temperature of step S2 is too high, or a hydrophobic end-capping agent (e.g., pentaerythritol triacrylate) is selected, or step S2 is not performed, the diisocyanate and sulfonate polyester polyol are prone to excessive polymerization or cross-linking, resulting in the obtained sulfonic acid-based waterborne polyurethane acrylate resin having too high a viscosity and poor stability.

[0016] Optionally, the diisocyanate in step S1 is at least one of 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, m-xylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate or toluene-2,4-diisocyanate.

[0017] Preferably, the diisocyanate in step S1 is at least one of isophorone diisocyanate, m-xylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate or toluene-2,4-diisocyanate.

[0018] A specific diisocyanate is preferred. At a specific temperature, the reactivity of the two -NCO groups in the specific diisocyanate molecule is more different. The resulting sulfonic acid-based waterborne polyurethane acrylate resin has a lower viscosity (less than 75 mPa·s) at a high solid content (30-40 wt%) and better storage stability (achieving excellent).

[0019] The sulfonic acid type waterborne polyurethane acrylate resin prepared by the preparation method of the present invention has good mechanical properties (such as flexibility) after curing and can meet basic usage requirements. Therefore, after adding the polymerization inhibitor to the diisocyanate in step S1, chain extension can be omitted and the end capping in step S2 can be directly performed; however, in order to further improve the flexibility of the resin after curing, appropriate chain extension can be performed.

[0020] Preferably, after adding the polymerization inhibitor to the diisocyanate in step S1, a chain extension step is also included.

[0021] Specifically, the chain extension step is: adding low molecular weight polyol and reacting until the -NCO content reaches the theoretical value; the molar ratio of -NCO of the diisocyanate to -OH of the low molecular weight polyol is 1:(0.05-0.2); the number average molecular weight of the low molecular weight polyol is 200-2000.

[0022] More specifically, the low molecular weight polyol is at least one of polyethylene glycol, polytetramethylene ether glycol, propylene glycol polyether or polycarbonate diol.

[0023] More specifically, the chain extension reaction temperature is 50-70°C.

[0024] Optionally, the polymerization inhibitor in step S1 is at least one of p-hydroxyanisole, hydroquinone, p-benzoquinone or nitrotoluene.

[0025] Typically, step S1 further includes the step of adding a catalyst.

[0026] Optionally, the catalyst is at least one of dibutyltin diacetate, dibutyltin dilaurate, zinc acetate, bismuth nitrate, stannous octoate, bismuth laurate, bismuth naphthenate or barium naphthenate.

[0027] Preferably, the reaction temperature in step S2 is 35-50°C.

[0028] Preferably, the dropping speed of adding the acrylate end-capping agent in step S2 is 1 drop / 8 to 15 seconds.

[0029] At this dropping speed, the temperature rise caused by the violent reaction of the system can be avoided more effectively, which is more conducive to the end-capping reaction.

[0030] Preferably, the acrylate end-capping agent in step S2 is at least one of 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate or 2-hydroxypropyl methacrylate.

[0031] Optionally, the sulfonate polyester polyol in step S3 has a number average molecular weight of 650 to 1500 and a hydroxyl value of 60 to 80 mgKOH / g.

[0032] Preferably, the sulfonate polyester polyol in step S3 is a linear sulfonate polyester polyol.

[0033] Preferably, before adding the sulfonate polyester polyol in step S3, the process further comprises subjecting the sulfonate polyester polyol to a viscosity reduction treatment at 70-100°C.

[0034] By carrying out viscosity reduction treatment at this temperature, the sulfonate polyester polyol can be prevented from adhering to the wall or climbing the pole, thereby improving the reaction efficiency.

[0035] Preferably, the reaction temperature in step S3 is 55-75°C.

[0036] Any commonly used acrylate end-capping agent in the art can be used in step S4 of the present invention.

[0037] Preferably, the acrylate end-capping agent in step S4 is a water-soluble acrylate end-capping agent.

[0038] More preferably, the water-soluble acrylate end-capping agent selected in step S4 is at least one of 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate or 2-hydroxypropyl methacrylate.

[0039] Preferably, the reaction temperature in step S4 is 60-75°C.

[0040] Typically, after the end-capping reaction in step S4, the steps of adding water and emulsifying are further included.

[0041] More preferably, the specific process of adding water is: adding water in 3 to 5 times.

[0042] Adding water in multiple times is more conducive to the full emulsification of the resin.

[0043] More preferably, the stirring speed of the emulsification is 1000-1500 r / min and the time is 20-30 min.

[0044] Preferably, the molar ratio of -NCO of the diisocyanate in step S1, -OH of the sulfonate polyester polyol in step S3, and -OH of the acrylate end-capping agent in step S4 is 1:(0.20-0.40):(0.30-0.50).

[0045] Preferably, the solid content of the sulfonic acid type waterborne polyurethane acrylate resin in step S4 is 30-40 wt %.

[0046] More preferably, when the solid content of the sulfonic acid type waterborne polyurethane acrylate resin is 30-40 wt%, the viscosity is 55-125 mPa·s.

[0047] A sulfonic acid type waterborne polyurethane acrylate resin is prepared by the preparation method claimed in claim 1.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The sulfonic acid-based waterborne polyurethane acrylate resin produced by the preparation method of the present invention can maintain low viscosity (less than 125 mPa·s) at a high solids content (30-40 wt%). The entire preparation process of this sulfonic acid-based waterborne polyurethane acrylate resin does not require the addition of organic solvents to reduce viscosity, making the preparation process environmentally friendly and economical. Furthermore, the resulting sulfonic acid-based waterborne polyurethane acrylate resin exhibits excellent or good storage stability. After further dilution (to a solids content of 3%), the emulsion contains only minimal or small amounts of sediment. Furthermore, using water as the dispersion medium, the resin is environmentally friendly, safe, and suitable as a base resin for water-based coatings. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is the infrared test spectrum of the sulfonic acid type water-based polyurethane acrylate resin of Example 1.

[0051] Figure 2 This is the infrared test spectrum of the sulfonic acid type water-based polyurethane acrylate resin of Example 4. DETAILED DESCRIPTION

[0052] In order to more clearly and completely describe the technical solution of the present invention, the present invention is further described in detail through specific embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Various changes can be made within the scope of the rights of the present invention.

[0053] Example 1

[0054] This embodiment provides a method for preparing a sulfonic acid type waterborne polyurethane acrylate resin, comprising the following steps:

[0055] 1. Install a digital electric stirrer and a mercury thermometer on a four-necked flask, add 22.2 g of isophorone diisocyanate (0.1 mol) into the four-necked flask, turn on the stirring device, and stir at a speed of 400 r / min. Add 1 drop of catalyst dibutyltin dilaurate and 0.2 g of free radical inhibitor nitrotoluene, and gradually raise the temperature to 60 °C.

[0056] 2. Weigh 6.5 g of polytetramethylene ether glycol (0.01 mol) with a molecular weight of 650 and add it dropwise into a constant pressure dropping funnel. After the addition is completed, continue to keep warm for 20 minutes. Take 1 g of the reaction intermediate and determine the -NCO content in the system. When the -NCO content approaches the theoretical value, proceed to the next step, otherwise continue to keep warm.

[0057] 3. Cool to 45°C, weigh 9.3g of 2-hydroxyethyl acrylate end-capping agent (0.08mol), add it to a constant pressure dropping funnel and slowly add it dropwise, controlling the dropping rate to 1 drop / 10s. After the addition is completed, continue to keep warm for 20min, take 1g of the reaction intermediate, and determine the -NCO content in the system. When the -NCO content approaches the theoretical value, gradually raise the temperature to 70°C, otherwise continue to keep warm.

[0058] 4. Add 45.0 g (0.03 mol) of sulfonate polyester polyol with a molecular weight of 1500 after high-temperature viscosity reduction (hydroxyl value of about 65 mg KOH / g), continue to keep warm at 70°C for 2 hours, take 1 g of the reaction intermediate, and measure the -NCO content in the system. When the -NCO content in the system approaches the theoretical value, raise the temperature to 75°C for the next step, otherwise continue to keep warm.

[0059] 5. Add the remaining 8.1g of 2-hydroxyethyl acrylate capping agent (0.07mol), keep warm at 75℃ for 2h, take 1g for titration, if -NCO is completely converted, stop heating and cool the system to 50℃, otherwise continue to keep warm.

[0060] 6. Weigh 169.3 g of deionized water and add it four times, gradually increase the stirring speed to 1200 r / min, continue stirring and emulsifying for 30 minutes, and finally obtain a sulfonic acid type water-based polyurethane acrylate resin with a solid content of about 35 wt%.

[0061] The infrared test of waterborne polyurethane acrylate resin before emulsification is carried out, and the infrared test spectrum is as follows Figure 1 As shown. Figure 1 It can be seen that 2280cm -1 There is no absorption peak nearby, indicating that the -NCO group has been completely reacted. -1 When it belongs to the -NH stretching vibration peak, 1709.93cm -1 When the characteristic absorption peak belongs to the carbonyl group, it indicates the formation of polyurethane structure. -1 When it belongs to the stretching vibration peak of the double bond of acrylate, 815.78cm -1 When it belongs to the out-of-plane bending vibration of CH in the acrylate double bond, it indicates that the product contains acrylate C=C double bond structure, 1171.70cm -1 When the asymmetric stretching vibration peak belongs to COC, it indicates the successful accession of polyether polyol (polytetramethylene ether glycol). -1 、629.65cm -1 The above infrared spectra prove that the sulfonic acid type waterborne polyurethane acrylate resin of the present invention has been successfully synthesized.

[0062] The structural formula of the main sulfonic acid type waterborne polyurethane acrylate resin molecule in the sulfonic acid type waterborne polyurethane acrylate resin of this embodiment is as follows:

[0063]

[0064] Wherein, n=1 to 10, m=1 to 6;

[0065] R1 is the portion of the capping agent (2-hydroxyethyl acrylate capping agent) that does not contain a terminal -OH group;

[0066] R is the portion of diisocyanate (isophorone diisocyanate) that does not contain an -NCO group;

[0067] R2 is the main part of a low molecular weight polyol (tetramethylene ether glycol) without terminal -OH;

[0068] R3 is the main part of the sulfonate polyester polyol without terminal -OH.

[0069] Example 2

[0070] This embodiment provides a method for preparing a sulfonic acid type waterborne polyurethane acrylate resin, comprising the following steps:

[0071] 1. Install a digital electric stirrer and a mercury thermometer on a four-necked flask, add 22.2 g of isophorone diisocyanate (0.10 mol) into the four-necked flask, turn on the stirring device, and stir at a speed of 400 r / min. Add 1 drop of catalyst dibutyltin diacetate and 0.2 g of free radical inhibitor hydroquinone, and gradually raise the temperature to 65 °C.

[0072] 2. Weigh 10.0 g (0.01 mol) of polycarbonate diol with a molecular weight of 1000 and add it dropwise into a constant pressure dropping funnel. After the addition is completed, continue to keep warm for 20 minutes. Take 1 g of the reaction intermediate and measure the -NCO content in the system. When the -NCO content approaches the theoretical value, proceed to the next step, otherwise continue to keep warm.

[0073] 3. Cool to 45°C, weigh 9.28g (0.08mol) of 2-hydroxyethyl acrylate, add it to a constant pressure dropping funnel and slowly add it dropwise. Control the dropping rate to 1 drop / 12s. After the addition is completed, continue to keep warm for 20min. Take 1g of the reaction intermediate and determine the -NCO content in the system. When the -NCO content approaches the theoretical value, gradually raise the temperature to 65°C, otherwise continue to keep warm.

[0074] 4. Add 45.0 g (0.03 mol) of sulfonate polyester polyol with a molecular weight of 1500 (hydroxyl value of about 65 mg KOH / g) after high-temperature viscosity reduction, continue to keep warm at 65°C for 2 hours, take 1 g of the reaction intermediate, and measure the -NCO content in the system. When the -NCO content in the system approaches the theoretical value, raise the temperature to 75°C for the next step, otherwise continue to keep warm.

[0075] 5. Add the remaining 7.0 g (0.06 mol) of 2-hydroxyethyl acrylate end-capping agent, keep warm at 75°C for 2 h, take 1 g for titration, if -NCO is completely converted, stop heating and cool the system to 50°C, otherwise continue to keep warm.

[0076] 6. Weigh 173.0 g of deionized water and add it four times, gradually increase the stirring speed to 1200 r / min, continue stirring and emulsifying for 30 minutes, and finally obtain a sulfonic acid type water-based polyurethane acrylate resin with a solid content of about 35 wt%.

[0077] The structural formula of the main sulfonic acid type waterborne polyurethane acrylate resin molecules in the sulfonic acid type waterborne polyurethane acrylate resin of this embodiment can be referred to Example 1, and the infrared test spectrum is the same as Figure 1 Similarly, IR spectrum proved that sulfonic acid type waterborne polyurethane acrylate resin was successfully synthesized.

[0078] Example 3

[0079] This embodiment provides a method for preparing a sulfonic acid type waterborne polyurethane acrylate resin, comprising the following steps:

[0080] 1. Install a digital electric stirrer and a mercury thermometer on a four-necked flask, add 26.2 g (0.10 mol) of 4,4'-dicyclohexylmethane diisocyanate into the four-necked flask, turn on the stirring device at a speed of 300 r / min, add 1 drop of catalyst bismuth laurate and 0.2 g of free radical inhibitor p-hydroxyanisole, and gradually raise the temperature to 60 °C.

[0081] 2. Weigh 6.5 g (0.01 mol) of polytetramethylene ether glycol with a number average molecular weight of 650 and add it dropwise into a constant pressure dropping funnel. After the addition is completed, continue to keep warm for 20 minutes. Take 1 g of the reaction intermediate and measure the -NCO content in the system. When the -NCO content approaches the theoretical value, proceed to the next step, otherwise continue to keep warm.

[0082] 3. Cool to 50°C, weigh 9.3g (0.08mol) of 2-hydroxyethyl acrylate end-capping agent, add it to the constant pressure dropping funnel and slowly add it dropwise, controlling the dropping rate to 1 drop / 10s. After the addition is completed, continue to keep warm for 20min, take 1g of the reaction intermediate, and determine the -NCO content in the system. When the -NCO content approaches the theoretical value, gradually raise the temperature to 65°C, otherwise continue to keep warm.

[0083] 4. Add 45.0 g (0.03 mol) of sulfonate polyester polyol with a molecular weight of 1500 (hydroxyl value of about 67 mg KOH / g) after high-temperature viscosity reduction, continue to keep warm at 65°C for 2 hours, take 1 g of the reaction intermediate, and measure the -NCO content in the system. When the -NCO content in the system approaches the theoretical value, raise the temperature to 70°C for the next step, otherwise continue to keep warm.

[0084] 5. Add the remaining 8.1 g (about 0.07 mol) of 2-hydroxyethyl acrylate end-capping agent, keep warm at 70°C for 2 hours, take 1 g for titration, if -NCO is completely converted, stop heating and cool the system to 50°C, otherwise continue to keep warm.

[0085] 6. Weigh 176.6 g of deionized water and add it three times, gradually increase the stirring speed to 1200 r / min, continue stirring and emulsifying for 30 minutes, and finally obtain a sulfonic acid type water-based polyurethane acrylate resin with a solid content of about 35 wt%.

[0086] The structural formula of the main sulfonic acid type waterborne polyurethane acrylate resin molecules in the sulfonic acid type waterborne polyurethane acrylate resin of this embodiment can be referred to Example 1, and the infrared test spectrum is the same as Figure 1 Similarly, IR spectrum proved that sulfonic acid type waterborne polyurethane acrylate resin was successfully synthesized.

[0087] Example 4

[0088] This embodiment provides a method for preparing a sulfonic acid type waterborne polyurethane acrylate resin, comprising the following steps:

[0089] 1. Install a digital electric stirrer and a mercury thermometer on a four-necked flask, add 22.2 g (0.10 mol) of isophorone diisocyanate into the four-necked flask, turn on the stirring device at a stirring speed of 400 r / min, and add 1 drop of catalyst dibutyltin dilaurate and 0.2 g of free radical inhibitor p-hydroxyanisole.

[0090] 2. Raise the temperature to 50°C, weigh 11.6 g (0.10 mol) of 2-hydroxyethyl acrylate, add it to the constant pressure dropping funnel and slowly add it dropwise. After the addition is completed, continue to keep warm for 20 minutes. Take 1 g of the reaction intermediate and measure the -NCO content in the system. When the -NCO content approaches the theoretical value, gradually raise the temperature to 70°C, otherwise continue to keep warm.

[0091] 3. Add 45.0 g (0.03 mol) of sulfonate polyester polyol with a molecular weight of 1500 (hydroxyl value of about 73 mg KOH / g) after high-temperature viscosity reduction, continue to keep warm at 70°C for 2 hours, take 1 g of the reaction intermediate, and measure the -NCO content in the system. When the -NCO content in the system approaches the theoretical value, raise the temperature to 75°C for the next step, otherwise continue to keep warm.

[0092] 4. Add the remaining 7.0 g (0.06 mol) of 2-hydroxyethyl acrylate end-capping agent, keep warm at 75°C for 2 h, take 1 g for titration, if -NCO is completely converted, stop heating and cool the system to 50°C, otherwise continue to keep warm.

[0093] 5. Weigh 160.2 g of deionized water and add it three times, gradually increase the stirring speed to 1200 r / min, continue stirring and emulsifying for 30 minutes, and finally obtain a sulfonic acid type water-based polyurethane acrylate resin with a solid content of about 35 wt%.

[0094] The infrared test of waterborne polyurethane acrylate resin before emulsification is carried out, and the infrared test spectrum is as follows Figure 2 As shown. Figure 2 It can be seen that 2280cm -1 There is no absorption peak nearby, indicating that the -NCO group has completed the reaction. -1 When it belongs to the -NH stretching vibration peak, 1730.57cm -1 The characteristic absorption peak of carbonyl group indicates the formation of polyurethane structure. -1 When it belongs to the stretching vibration peak of the double bond of acrylate, 826.62 cm -1 When it belongs to the out-of-plane bending vibration of CH in the acrylate double bond, it indicates that the product contains the acrylate C=C double bond structure, 1057.63cm -1 、918.76cm -1 、629.65cm -1 The above infrared spectra prove that the sulfonic acid type waterborne polyurethane acrylate resin was successfully synthesized.

[0095] The structural formula of the main sulfonic acid type waterborne polyurethane acrylate resin molecule in the sulfonic acid type waterborne polyurethane acrylate resin of this embodiment is as follows:

[0096]

[0097] Medium, t = 1 to 10;

[0098] R4 end-capping agent (2-hydroxyethyl acrylate) does not contain a terminal -OH portion;

[0099] R' is an alkyl portion of a diisocyanate (isophorone diisocyanate) that does not contain an -NCO group;

[0100] R5 is the main part of the sulfonate polyester polyol without terminal -OH.

[0101] Comparative Example 1

[0102] This comparative example provides a preparation method of a comparative sulfonic acid type waterborne polyurethane acrylate resin, comprising the following steps:

[0103] 1. Install a digital electric stirrer and a mercury thermometer on a four-necked flask, add 26.2 g (0.10 mol) of 4,4'-dicyclohexylmethane diisocyanate into the four-necked flask, turn on the stirring device at a speed of 400 r / min, add 1 drop of catalyst bismuth laurate and 0.2 g of free radical inhibitor p-hydroxyanisole, and gradually raise the temperature to 60°C.

[0104] 2. Weigh 13.0 g (0.02 mol) of polytetramethylene ether glycol with a number average molecular weight of 650 and add it dropwise into a constant pressure dropping funnel. After the addition is completed, continue to keep warm for 20 minutes. Take 1 g of the reaction intermediate and determine the -NCO content in the system. When the -NCO content approaches the theoretical value, proceed to the next step, otherwise continue to keep warm.

[0105] 3. Cool to 55°C, weigh 7.0 g (0.06 mol) of 2-hydroxyethyl acrylate end-capping agent, add it to the constant pressure dropping funnel and slowly add it dropwise, controlling the dropping rate to 1 drop / 12 s. After the addition is completed, continue to keep warm for 20 minutes, take 1 g of the reaction intermediate, and determine the -NCO content in the system. When the -NCO content approaches the theoretical value, gradually raise the temperature to 70°C, otherwise continue to keep warm.

[0106] 4. Add 45.0 g (0.03 mol) of sulfonate polyester polyol with a molecular weight of 1500 after high-temperature viscosity reduction (hydroxyl value of about 67 mg KOH / g), continue to keep warm at 70°C for 2 hours, take 1 g of the reaction intermediate, and measure the -NCO content in the system. When the -NCO content in the system approaches the theoretical value, raise the temperature to 75°C for the next step, otherwise continue to keep warm.

[0107] 5. Add the remaining 8.1 g (0.07 mol) of 2-hydroxyethyl acrylate capping agent, keep warm at 75°C for 2 h, take 1 g for titration, if -NCO is completely converted, stop heating and cool the system to 50°C, otherwise continue to keep warm.

[0108] 6. Weigh 184.4 g of deionized water and add it three times, gradually increase the stirring speed to 1200 r / min, continue stirring and emulsifying for 30 minutes, and finally obtain a comparative sulfonic acid type water-based polyurethane acrylate resin with a solid content of about 35 wt%.

[0109] Comparative Example 2

[0110] This comparative example provides a preparation method of a comparative sulfonic acid type waterborne polyurethane acrylate resin, comprising the following steps:

[0111] 1. Install a digital electric stirrer and a mercury thermometer on a four-necked flask, add 26.2 g (0.10 mol) of 4,4'-dicyclohexylmethane diisocyanate into the four-necked flask, turn on the stirring device at a speed of 400 r / min, add 1 drop of catalyst dibutyltin diacetate and 0.2 g of free radical inhibitor p-hydroxyanisole, and gradually raise the temperature to 60 °C.

[0112] 2. Weigh 5.0 g (0.02 mol) of polytetramethylene ether glycol with a number average molecular weight of 250 and add it dropwise into a constant pressure dropping funnel. After the addition is completed, continue to keep warm for 20 minutes. Take 1 g of the reaction intermediate and determine the -NCO content in the system. When the -NCO content approaches the theoretical value, proceed to the next step, otherwise continue to keep warm.

[0113] 3. Cool to 50°C, weigh 24.4 g (about 0.08 mol) of pentaerythritol triacrylate, add it to a constant pressure dropping funnel and slowly add it dropwise. Control the dropping rate to 1 drop / 12 s. After the addition is completed, continue to keep warm for 20 minutes. Take 1 g of the reaction intermediate and determine the -NCO content in the system. When the -NCO content approaches the theoretical value, gradually raise the temperature to 65°C, otherwise continue to keep warm.

[0114] 4. Add 45.0 g (0.03 mol) of sulfonate polyester polyol with a molecular weight of 1500 (hydroxyl value of about 65 mg KOH / g) after high-temperature viscosity reduction, continue to keep warm at 65°C for 2 hours, take 1 g of the reaction intermediate, and measure the -NCO content in the system. When the -NCO content in the system approaches the theoretical value, raise the temperature to 70°C for the next step, otherwise continue to keep warm.

[0115] 5. Add the remaining 16.2 g (about 0.05 mol) of pentaerythritol triacrylate capping agent, keep warm at 70 ° C for 2 hours, take 1 g for titration, if -NCO is completely converted, stop heating and cool the system to 50 ° C, otherwise continue to keep warm.

[0116] 6. Weigh 217.7 g of deionized water and add it four times, gradually increase the stirring speed to 1200 r / min, continue stirring and emulsifying for 30 minutes, and finally obtain a comparative sulfonic acid type water-based polyurethane acrylate resin with a solid content of about 35 wt%.

[0117] Comparative Example 3

[0118] This comparative example provides a preparation method of a comparative sulfonic acid type waterborne polyurethane acrylate resin, comprising the following steps:

[0119] 1. Install a digital electric stirrer and a mercury thermometer on a four-necked flask, add 22.2 g (0.10 mol) of isophorone diisocyanate into the four-necked flask, turn on the stirring device at a speed of 400 r / min, add 1 drop of catalyst dibutyltin dilaurate and 0.2 g of free radical inhibitor nitrotoluene, and gradually raise the temperature to 65 °C.

[0120] 2. Weigh 5.0 g (0.02 mol) of polytetramethylene ether glycol with a number average molecular weight of 250 and add it dropwise into a constant pressure dropping funnel. After the addition is completed, continue to keep warm for 20 minutes. Take 1 g of the reaction intermediate and determine the -NCO content in the system. When the -NCO content approaches the theoretical value, proceed to the next step, otherwise continue to keep warm.

[0121] 3. Cool to 45°C, weigh 24.4 g (about 0.08 mol) of pentaerythritol triacrylate, add it to a constant pressure dropping funnel and slowly add it dropwise. Control the dropping rate to 1 drop / 10 s. After the addition is completed, continue to keep warm for 20 minutes. Take 1 g of the reaction intermediate and determine the -NCO content in the system. When the -NCO content approaches the theoretical value, gradually raise the temperature to 65°C, otherwise continue to keep warm.

[0122] 4. Add 60.0 g (0.04 mol) of sulfonate polyester polyol with a molecular weight of 1500 (hydroxyl value of about 67 mg KOH / g) after high-temperature viscosity reduction, continue to keep warm at 65°C for 2 hours, take 1 g of the reaction intermediate, and measure the -NCO content in the system. When the -NCO content in the system approaches the theoretical value, raise the temperature to 70°C for the next step, otherwise continue to keep warm.

[0123] 5. Add the remaining 6.1 g (about 0.02 mol) of pentaerythritol triacrylate capping agent, keep warm at 70°C for 2 hours, take 1 g for titration, if -NCO is completely converted, stop heating and cool the system to 50°C, otherwise continue to keep warm.

[0124] 6. Weigh 219.3 g of deionized water and add it three times, gradually increase the stirring speed to 1500 r / min, continue stirring and emulsifying for 20 minutes, and finally obtain a sulfonic acid type water-based polyurethane acrylate resin with a solid content of about 35 wt%.

[0125] Performance Testing

[0126] The following tests were conducted on the sulfonic acid type waterborne polyurethane acrylate resins of each example and the comparative sulfonic acid type waterborne polyurethane acrylate resins of each comparative example:

[0127] Viscosity: According to GB / T10247-2008, a rotational viscometer was used to test the viscosity of samples with a solid content of 35%.

[0128] Appearance: visual inspection.

[0129] Storage stability: Test the stability at 25°C. The specific process is: if the emulsion is stored at 25°C for more than 180 days without stratification, it can be proved that the emulsion has excellent storage stability and meets the needs of industrial production; if stratification occurs within 7 to 180 days, it proves that the emulsion has good stability; if stratification occurs within 7 days, it proves that the emulsion has poor stability.

[0130] Emulsion Sediment: Further dilute the emulsion to a solids content of 3wt%, transfer it to a test tube, and let it stand for 72 hours. If the upper clear liquid appears bluish after standing, observe the volume ratio of the upper clear liquid to the lower sediment. If the volume ratio is greater than or equal to 1000, or if no sediment is observed at the bottom, the emulsion is considered to have minimal sediment. If the volume ratio is less than 1000, a small amount of sediment is present. If the upper clear liquid is colorless and transparent after standing, with distinct stratification, the emulsion is essentially completely settled, indicating the presence of a large amount of sediment.

[0131] The test results of various properties are shown in Table 1.

[0132] Table 1 Performance test results of various embodiments and comparative examples

[0133]

[0134]

[0135] From Table 1 we can see that:

[0136] In Examples 1 to 4, the sulfonic acid-based waterborne polyurethane acrylate resins prepared using the present invention all had low viscosities (less than 125 mPa·s) at a solid content of 35%; a milky white appearance with a bluish tint; and excellent storage stability at 25° C.; and after further dilution (solid content of 3%), only a small amount or very little sediment remained at the bottom of the emulsion.

[0137] In the second step of Comparative Example 1, the molar amount of polytetramethylene ether glycol added was relatively large, and the degree of chain extension was relatively large, resulting in a certain degree of increase in the viscosity of the comparative sulfonic acid type waterborne polyurethane acrylate resin. In addition, the temperature control during the end-capping reaction in the third step was improper (55° C.), resulting in a further increase in the viscosity of the comparative sulfonic acid type waterborne polyurethane acrylate resin. In addition, the storage stability was poor, and after further dilution (solid content of 3%), a large amount of sediment was found at the bottom of the emulsion.

[0138] The end-capping agent selected in step 3 of Comparative Example 2 has poor hydrophilicity (pentaerythritol triacrylate, a hydrophobic end-capping agent), resulting in the obtained comparative sulfonic acid type waterborne polyurethane acrylate resin having too high a viscosity and poor storage stability. After further dilution (solid content of 3%), there is a large amount of sediment at the bottom of the emulsion.

[0139] In the second step of Comparative Example 3, the molar amount of polytetramethylene ether glycol added was relatively large, and the degree of chain extension was relatively large, resulting in a certain degree of increase in the viscosity of the comparative sulfonic acid type waterborne polyurethane acrylate resin. The poor hydrophilicity of the end-capping agent selected in the third step (pentaerythritol triacrylate) resulted in a significantly higher viscosity of the comparative sulfonic acid type waterborne polyurethane acrylate resin, reaching 4500 mPa·s at a solid content of 35%. In addition, the storage stability was poor, and a large amount of sediment was found at the bottom of the emulsion after further dilution (solid content of 3%).

[0140] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a sulfonic acid type waterborne polyurethane acrylate resin, characterized in that: The steps include: S1. Adding an inhibitor to the diisocyanate; S2. Adding an acrylate capping agent to perform a capping reaction; S3. Add sulfonate polyester polyol and react; S4 is added acrylate capping agent, capping reaction, to obtain the sulfonic acid type waterborne polyurethane acrylate resin; The molar ratio of -NCO of the diisocyanate in step S1 to -OH of the acrylate end-capping agent in step S2 is 1:(0.30-0.60); the acrylate end-capping agent in step S2 is a water-soluble acrylate end-capping agent; and the reaction temperature in step S2 is ≤50°C.

2. The preparation method according to claim 1, characterized in that The diisocyanate in step S1 is at least one of 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, m-xylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate or toluene-2,4-diisocyanate.

3. The preparation method according to claim 1, characterized in that: After adding the polymerization inhibitor to the diisocyanate in step S1, a chain extension step is also included; the chain extension step is: adding a low molecular weight polyol and reacting until the -NCO content reaches a theoretical value; the molar ratio of -NCO of the diisocyanate to -OH of the low molecular weight polyol is less than or equal to 1:0.05 and greater than 1:0.

2.

4. The preparation method according to claim 1, characterized in that The acrylate end-capping agent in step S2 is at least one of 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate or 2-hydroxypropyl methacrylate.

5. The preparation method according to claim 1, characterized in that: The sulfonate polyester polyol in step S3 has a number average molecular weight of 650-1500 and a hydroxyl value of 60-80 mgKOH / g.

6. The preparation method according to claim 1, characterized in that: The acrylate end-capping agent in step S4 is a water-soluble acrylate end-capping agent.

7. The preparation method according to claim 1, characterized in that: The molar ratio of -NCO of the diisocyanate in step S1, -OH of the sulfonate polyester polyol in step S3, and -OH of the acrylate end-capping agent in step S4 is 1:(0.20-0.40):(0.30-0.50).

8. The preparation method according to claim 1, characterized in that: The reaction temperature in step S2 is 35-50°C.

9. The preparation method according to claim 1, characterized in that: The solid content of the sulfonic acid type waterborne polyurethane acrylate resin in step S4 is 30-40 wt %.

10. A sulfonic acid type waterborne polyurethane acrylate resin, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 9.

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