Synthesis method of polyurethane / polyacrylate hybrid resin emulsion stable in high-ethanol-content system

Abstract

The invention discloses a method for synthesizing a polyurethane / polyacrylate hybrid resin emulsion that is stable in a high-ethanol-content system. The synthesis of the resin is carried out in two steps: first, a waterborne polyurethane resin emulsion is synthesized, and then, using this waterborne polyurethane resin emulsion as the starting emulsion, ethanol, a dispersant, an initiator, and acrylate monomers are added and reacted at a certain temperature to obtain the target product. The polyurethane / polyacrylate hybrid resin emulsion of the invention can be mixed with water or ethanol in any proportion and maintain the storage stability of the resin emulsion. This polyurethane / polyacrylate hybrid resin emulsion can be applied in multiple fields such as leather, ink, adhesives, coatings, etc.

Description

Technical Field

[0001] The present invention relates to a method for synthesizing a polyurethane / polyacrylate hybrid resin emulsion. The polyurethane / polyacrylate hybrid resin emulsion synthesized by the method of the present invention has good compatibility with both water and ethanol, can be mixed with water or ethanol in any proportion, and maintains the storage stability of the resin emulsion. Background Art

[0002] Polymer resin materials have very wide applications in industries such as leather, ink, binder, coating, etc. Traditional solvent-based resin materials have gradually been restricted in their use due to their potential hazards in terms of environmental protection, safety, and health. Waterborne resin materials are a type of green and environmentally friendly resin material actively promoted by the country to replace solvent-based resin materials. However, currently, products such as inks and coatings produced from waterborne resin materials still have disadvantages such as poor leveling property and slow drying speed compared with solvent-based resin materials. In order to eliminate such a gap, a certain amount of ethanol is generally added to waterborne gravure printing inks. The national standard GB38507-2020 stipulates that for gravure printing inks used on non-absorbent printing substrates, no more than 30% of ethanol can be added.

[0003] The compatibility between waterborne resin materials and ethanol is generally poor. Most acrylate resin emulsions will undergo demulsification when 10% of ethanol is added. Many waterborne polyurethane resin emulsions will also have an increase in viscosity and even gelation as the storage time increases after adding 20% of ethanol. Therefore, solving the compatibility problem between waterborne resin materials and ethanol to improve their storage stability in the ethanol / water system has always been a difficult point in the waterborne ink industry. Summary of the Invention

[0004] In view of the problems existing in the prior art, the present invention provides a method for synthesizing a polyurethane / polyacrylate hybrid resin emulsion that is stable in a high-ethanol-content system.

[0005] The present invention adopts a two-step synthesis method. First, a waterborne polyurethane resin emulsion is synthesized, and then, using this waterborne polyurethane resin emulsion as the starting emulsion, ethanol, acrylate monomers, a dispersant, and an initiator are added, and a reaction is carried out at a certain temperature to obtain a new type of polyurethane / polyacrylate hybrid resin emulsion. This resin emulsion has good compatibility with both water and ethanol, can be mixed with water or ethanol in any proportion, and always maintains the storage stability of the resin emulsion.

[0006] The technical solution of the present invention is as follows:

[0007] A method for synthesizing a polyurethane / polyacrylate hybrid resin emulsion, wherein the synthesis method is (the following parts are all by weight):

[0008] (1) Synthesis of waterborne polyurethane resin emulsion

[0009] Add 5-30 parts of polyol, 0.5-8 parts of hydrophilic monomer, 0-30 parts of solvent and 0-1 parts of catalyst into a reactor, stir and heat to 40-120° C., add 5-30 parts of diisocyanate, stir and react for 3-5 hours, then add 0-5 parts of chain extender and 0-5 parts of neutralizer, stir evenly to obtain a polyurethane prepolymer; control the temperature of the polyurethane prepolymer at 20-60° C., add 50-80 parts of water, 0-5 parts of chain extender and 0-5 parts of other additives under high-speed stirring (500-2000RPM), mix well, and remove the solvent by reduced pressure distillation as needed to obtain an aqueous polyurethane resin emulsion;

[0010] The molecular weight of the polyol is 60-20000 g / mol, and can be one of small molecule polyols and macromolecular polyols, or a mixture of two or more of them in any proportion; small molecule polyols include ethylene glycol, propylene glycol, 1,4-butanediol, pentaerythritol, etc.; macromolecular polyols include polyester polyols, polyether polyols, polycarbonate polyols, polyacrylate polyols, silicone polyols, etc.;

[0011] The hydrophilic monomer is selected from one of anionic carboxylic acid polyols, sulfonic acid polyols, and cationic tertiary amine polyols, or a mixture of two or more of the same type of polyols in any proportion; anionic carboxylic acid polyols such as dimethylol propionic acid; sulfonic acid polyols such as hydroquinone sulfonic acid; cationic tertiary amine polyols such as N-methyldiethanolamine;

[0012] The solvent is selected from one or a mixed solvent of any proportion of acetone, butanone, cyclohexanone, N,N-dimethylformamide, N,N-diethylformamide, N-methylpyrrolidone, and N-ethylpyrrolidone;

[0013] The catalyst is selected from organic tin compounds, organic bismuth compounds or tertiary amine compounds; specific examples include dibutyltin dilaurate, triethylenediamine, etc.;

[0014] The diisocyanate is selected from one or a mixture of two or more of aromatic diisocyanates, aliphatic or alicyclic diisocyanates in any proportion; aromatic diisocyanates include toluene diisocyanate and methylene diphenyl diisocyanate; aliphatic or alicyclic diisocyanates include hexamethylene diisocyanate, isophorone diisocyanate, and hydrogenated MDI;

[0015] The chain extender is selected from small molecule diols or small molecule diamines; small molecule diols such as ethylene glycol and propylene glycol; small molecule diamines such as ethylenediamine and propylenediamine;

[0016] The neutralizing agent is selected from triethylamine, ammonia water, sodium hydroxide, etc. for anionic hydrophilic monomers, or hydrochloric acid, acetic acid, etc. for cationic hydrophilic monomers;

[0017] The other additives are selected from one or more of a neutralizing agent and a surfactant;

[0018] (2) Synthesis of polyurethane / polyacrylate hybrid resin emulsion

[0019] Add 5 - 30 parts of the aqueous polyurethane resin emulsion synthesized in step (1), 10 - 60 parts of ethanol, and 0.1 - 5 parts of a dispersant into a reactor, stir and heat to 40 - 100 °C, add 0.1 - 2 parts of an initiator, and then start to dropwise add 1 - 40 parts of acrylate monomers. After the dropping is completed, continue the insulation reaction for 1 - 3 h, and then cool to room temperature to obtain a polyurethane / polyacrylate hybrid resin emulsion;

[0020] The dispersant can be a water-soluble polymer compound, such as: polyvinyl alcohol, polyvinylpyrrolidone, polyacrylate, etc.;

[0021] The initiator can be one or more of organic peroxide or azo radical initiators, specifically for example: benzoyl peroxide, azobisisobutyronitrile, etc.;

[0022] The acrylate monomers are selected from esters of acrylic acid and its homologues, and one or a mixture of two or more of other monomers that can undergo free radical copolymerization reactions with acrylate monomers in any proportion; esters of acrylic acid and its homologues such as: methyl acrylate, n-butyl acrylate, methyl methacrylate, etc.; other monomers that can undergo free radical copolymerization reactions with acrylate monomers such as: acrylonitrile, styrene, vinyl acetate, etc.

[0023] The beneficial effects of the present invention are as follows:

[0024] The present invention provides a polyurethane / polyacrylate hybrid resin emulsion. The synthesis of this resin is carried out in two steps: first, an aqueous polyurethane resin emulsion is synthesized, and then, using this aqueous polyurethane resin emulsion as the starting emulsion, ethanol, a dispersant, an initiator, and acrylate monomers are added and reacted at a certain temperature to obtain the target product.

[0025] The polyurethane / polyacrylate hybrid resin emulsion of the present invention can be mixed with water or ethanol in any proportion and maintain the storage stability of the resin emulsion. This polyurethane / polyacrylate hybrid resin emulsion can be applied in multiple fields such as leather, ink, binder, coating, etc. Specific embodiments

[0026] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0027] In the following examples, the polyester polyol was purchased from Stepan Chemical Co., Ltd., with the product number PC-1011-55, and the polyether polyol was purchased from Dow Chemical Company, with the product number VORANOL TM 2000LM. All other chemical reagents were purchased from Sinopharm Reagent Network.

[0028] Example 1

[0029] 167.7 g of polyester polyol, 15.5 g of dimethylolpropionic acid, and 112 g of acetone were added to a reaction kettle and stirred and heated to 60 °C. 69.4 g of toluene diisocyanate was added to the reaction kettle and stirred for reaction for 4 hours. 23.8 g of triethylamine and 9.0 g of ethylene glycol were added to the reaction kettle and stirred evenly. After the reactants were cooled to 40 °C, they were vigorously stirred, and at the same time 476.6 g of water was added. After thorough mixing, under vacuum, the temperature was gradually raised to 80 °C to distill out the acetone. During the distillation of acetone, the heating rate was controlled to prevent the generation of a large number of bubbles. Finally, a light blue translucent aqueous polyurethane resin emulsion was obtained.

[0030] Example 2

[0031] 167.7 g of polyether polyol, 15.5 g of dimethylolpropionic acid, 6.2 g of 1,4-butanediol, 0.37 g of dibutyltin dilaurate, and 112 g of acetone were added to a reaction kettle and stirred and heated to 55 °C. 82.6 g of isophorone diisocyanate was added to the reaction kettle and stirred for reaction for 4 hours. 23.8 g of triethylamine was added to the reaction kettle and stirred evenly. Then, after the reactants were cooled to 40 °C, they were vigorously stirred, and at the same time 476.6 g of water was added. Subsequently, 5.8 g of ethylenediamine was added. After thorough mixing, under vacuum, the temperature was gradually raised to 80 °C to distill out the acetone. During the distillation of acetone, the heating rate was controlled to prevent the generation of a large number of bubbles. Finally, a light blue translucent aqueous polyurethane resin emulsion was obtained.

[0032] Example 3

[0033] 250 g of the aqueous polyurethane resin emulsion of Example 1, 140 g of ethanol, and 10 g of polyvinylpyrrolidone PVP K-30 were added to a reaction kettle and stirred and heated to 65 °C. 2.5 g of azobisisobutyronitrile was added, and then a mixed solution of 25 g of n-butyl acrylate and 50 g of methyl methacrylate was added dropwise, and the dropwise addition was completed within 4 hours. After the dropwise addition was completed, the reaction was continued at 65 °C for 2 hours. After the reactants were cooled to room temperature, a milky white polyurethane / polyacrylate hybrid resin emulsion was obtained.

[0034] Example 4

[0035] 250 g of the aqueous polyurethane resin emulsion of Example 2, 140 g of ethanol, and 10 g of polyvinylpyrrolidone PVP K-30 were added to a reaction kettle, stirred and heated to 65 °C, 4.2 g of benzoyl peroxide was added, and then a mixture of 25 g of n-butyl acrylate and 50 g of styrene was added dropwise, and the dropwise addition was completed within 4 hours. After the dropwise addition was completed, the reaction was continued at 65 °C for 2 hours. After the reactant was cooled to room temperature, a milky white polyurethane / polyacrylate hybrid resin emulsion was obtained.

[0036] Comparative Example 5

[0037] 450 g of water, 4 g of n-butyl acrylate, 7.25 g of methyl methacrylate, 0.25 g of acrylic acid, 4.8 g of sodium dodecylbenzenesulfonate, and 4.5 g of sodium bicarbonate were added to a reaction kettle, stirred and heated to 75 °C, 3.5 g of potassium persulfate was added, and then a mixture of 76 g of n-butyl acrylate, 147.25 g of methyl methacrylate, and 4.75 g of acrylic acid was added dropwise, and the dropwise addition was completed within 4 hours. After the dropwise addition was completed, the reaction was continued at 75 °C for 1 hour. After the reactant was cooled to room temperature, a milky white aqueous polyacrylate resin emulsion was obtained.

[0038] Comparative Example 6

[0039] 250 g of the aqueous polyurethane resin emulsion of Example 1 and 215 g of the aqueous polyacrylate resin emulsion of Comparative Example 5 were mixed evenly to obtain a milky white aqueous polyurethane / polyacrylate mixed resin emulsion.

[0040] Comparative Example 7

[0041] 250 g of the aqueous polyurethane resin emulsion of Example 2 and 215 g of the aqueous polyacrylate resin emulsion of Comparative Example 5 were mixed evenly to obtain a milky white aqueous polyurethane / polyacrylate mixed resin emulsion.

[0042] The performance indexes and test results of the above resin emulsions are shown in the following table:

[0043] Performance Indexes and Test Results of Resin Emulsions

[0044]

[0045] To evaluate the stability of these resin emulsions in an ethanol system, Examples 1-4 and Comparative Examples 5-7 were respectively mixed evenly with water and ethanol in a ratio of 4:1, 3:2, 2:3, and 1:4, placed at room temperature, and their viscosity changes were observed. The evaluation results are as follows:

[0046] Viscosity / mPa·s (25 °C) after mixing the resin emulsion and water in a ratio of 4:1

[0047] Detection time (days) 0 1 2 4 7 14 28 56 100 Example 1 90 95 90 90 95 95 90 95 90 Example 2 100 100 95 95 95 95 100 100 95 Example 3 18 17 17 17 18 17 17 17 17 Example 4 15 15 16 16 16 15 15 15 16 Comparative Example 5 15 15 14 15 14 15 15 14 14 Comparative Example 6 15 14 14 15 15 15 15 14 14 Comparative Example 7 15 14 14 15 14 15 14 15 15

[0048] Viscosity / mPa·s (25 °C) after mixing resin emulsion and water in a ratio of 3:2

[0049] Detection time (days) 0 1 2 4 7 14 28 56 100 Example 1 65 65 65 65 70 65 65 65 65 Example 2 70 70 65 70 70 70 65 70 70 Example 3 12 12 11 11 12 12 12 12 12 Example 4 12 12 12 11 12 12 12 11 12 Comparative Example 5 11 11 11 10 11 11 11 11 11 Comparative Example 6 11 11 12 12 12 11 12 11 11 Comparative Example 7 12 11 11 10 11 12 11 10 11

[0050] Viscosity / mPa·s (25 °C) after mixing resin emulsion and water in a ratio of 2:3

[0051] Detection time (days) 0 1 2 4 7 14 28 56 100 Example 1 25 26 27 27 26 26 26 27 26 Example 2 28 28 30 28 28 28 29 28 28 Example 3 8 8 7 8 8 8 7 7 8 Example 4 5 6 6 6 7 6 6 6 6 Comparative Example 5 6 6 7 6 7 6 6 6 6 Comparative Example 6 6 6 5 6 5 6 6 6 6 Comparative Example 7 7 6 7 6 6 7 6 6 6

[0052] Viscosity / mPa·s (25 °C) after mixing resin emulsion and water in a ratio of 1:4

[0053] Detection time (days) 0 1 2 4 7 14 28 56 100 Example 1 18 18 18 19 19 19 19 19 19 Example 2 19 19 19 18 19 19 18 18 19 Example 3 3 3 3 4 3 3 3 3 3 Example 4 3 4 3 4 4 4 3 4 4 Comparative Example 5 3 3 3 3 3 4 3 3 3 Comparative Example 6 3 3 4 4 3 4 3 4 4 Comparative Example 7 3 2 3 2 3 4 3 3 3

[0054] Viscosity / mPa·s (25 °C) after mixing resin emulsion and ethanol in a ratio of 4:1

[0055] Detection time (days) 0 1 2 4 7 14 28 56 100 Example 1 80 120 200 540 950 Gel - - - Example 2 95 150 265 800 1250 Gel - - - Example 3 15 15 14 15 14 14 15 14 15 Example 4 14 15 14 16 14 14 15 14 14 Comparative Example 5 Demulsification - - - - - - - - Comparative Example 6 Demulsification - - - - - - - - Comparative Example 7 Demulsification - - - - - - - -

[0056] Viscosity / mPa·s (25 °C) after mixing resin emulsion and ethanol in a ratio of 3:2

[0057] Detection time (days) 0 1 2 4 7 14 28 56 100 Example 1 50 150 420 840 1450 Gel - - - Example 2 60 145 460 1000 1800 Gel - - - Example 3 11 11 11 12 11 11 12 11 12 Example 4 11 12 12 11 12 12 12 11 12 Comparative Example 5 Demulsification - - - - - - - - Comparative Example 6 Demulsification - - - - - - - - Comparative Example 7 Demulsification - - - - - - - -

[0058] Viscosity / mPa·s (25 °C) after mixing resin emulsion and ethanol in a ratio of 2:3

[0059] Detection time (days) 0 1 2 4 7 14 28 56 100 Example 1 35 115 850 1800 Gel - - - - Example 2 40 150 650 1100 2300 Gel - - - Example 3 5 5 5 4 5 5 4 5 5 Example 4 5 5 4 4 5 4 5 5 4 Comparative Example 5 Demulsification - - - - - - - - Comparative Example 6 Demulsification - - - - - - - - Comparative Example 7 Demulsification - - - - - - - -

[0060] Viscosity / mPa·s (25 °C) after mixing resin emulsion and ethanol in a ratio of 1:4

[0061] Detection time (days) 0 1 2 4 7 14 28 56 100 Example 1 15 850 1500 3500 Gel - - - - Example 2 15 150 1600 2800 Gel - - - - Example 3 2 2 2 2 3 2 3 3 2 Example 4 3 3 2 3 3 2 3 3 3 Comparative Example 5 Demulsification - - - - - - - - Comparative Example 6 Demulsification - - - - - - - - Comparative Example 7 Demulsification - - - - - - - -

[0062] It can be seen from the results of these evaluation experiments that these resin emulsions and water have relatively good compatibility. However, the compatibility of ordinary aqueous polyurethane resin emulsions (Example 1, Example 2), aqueous acrylate resin emulsions (Comparative Example 5), and aqueous polyurethane / polyacrylate hybrid resin emulsions (Comparative Example 6, Comparative Example 7) with ethanol is poor. In contrast, the polyurethane / polyacrylate hybrid resin emulsion (Example 3, Example 4) obtained by the synthesis method of the present invention has very good compatibility with ethanol and can be mixed with ethanol in any ratio without affecting its storage stability. The polyurethane / polyacrylate hybrid resin emulsion obtained by the synthesis method of the present invention can be applied in multiple fields such as leather, ink, binder, and coating to solve the problems of poor leveling property and slow drying speed of ordinary aqueous resin emulsions.

[0063] The above embodiments are used to explain the present invention rather than limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims of the present invention fall within the protection scope of the present invention.

Claims

1. A method for synthesizing a polyurethane / polyacrylate hybrid resin emulsion, characterized in that, The synthetic method is: (1) Synthesis of waterborne polyurethane resin emulsion Add 5-30 parts of polyol, 0.5-8 parts of hydrophilic monomer, 0-30 parts of solvent and 0-1 parts of catalyst into a reactor, stir and heat to 40-120° C., add 5-30 parts of diisocyanate, stir and react for 3-5 hours, then add 0-5 parts of chain extender and 0-5 parts of neutralizer, stir evenly to obtain a polyurethane prepolymer; control the temperature of the polyurethane prepolymer at 20-60° C., add 50-80 parts of water, 0-5 parts of chain extender and 0-5 parts of other additives under high-speed stirring, mix well, and remove the solvent by reduced pressure distillation as needed to obtain an aqueous polyurethane resin emulsion; The molecular weight of the polyol is 60-20000 g / mol; The hydrophilic monomer is dimethylol propionic acid; The catalyst is selected from an organic tin compound, an organic bismuth compound or a tertiary amine compound; The diisocyanate is selected from one or a mixture of two or more of aromatic diisocyanates, aliphatic or alicyclic diisocyanates in any proportion; The chain extender is selected from small molecule diols or small molecule diamines; (2) Synthesis of polyurethane / polyacrylate hybrid resin emulsion Add 5-30 parts of the aqueous polyurethane resin emulsion synthesized in step (1), 10-60 parts of ethanol, and 0.1-5 parts of a dispersant into a reactor, stir and heat to 40-100° C., add 0.1-2 parts of an initiator, and then start to dropwise add 1-40 parts of an acrylate monomer. After the dropwise addition is completed, continue to heat and react for 1-3 hours, then cool to room temperature to obtain a polyurethane / polyacrylate hybrid resin emulsion; The dispersant is selected from: polyvinyl alcohol or polyvinyl pyrrolidone; The initiator is selected from one or more free radical initiators of organic peroxide or azo type; The acrylate monomer is selected from esters of acrylic acid and its homologues, or a mixture of one or more of esters of acrylic acid and its homologues and other monomers capable of free radical copolymerization with the acrylate monomer in any proportion.

2. The synthesis method of the polyurethane / polyacrylate hybrid resin emulsion according to claim 1, characterized in that, In step (1), the polyol is selected from one of small molecule polyols and macromolecular polyols, or a mixture of two or more of them in any proportion; the small molecule polyol is selected from ethylene glycol, propylene glycol, 1,4-butanediol, and pentaerythritol; the macromolecular polyol is selected from polyester polyols, polyether polyols, polycarbonate polyols, polyacrylate polyols, and silicone polyols.

3. The synthesis method of the polyurethane / polyacrylate hybrid resin emulsion according to claim 1, wherein, In step (1), the solvent is selected from one or a mixed solvent of two or more of acetone, butanone, cyclohexanone, N,N-dimethylformamide, N,N-diethylformamide, N-methylpyrrolidone, and N-ethylpyrrolidone in any proportion.

4. The synthesis method of the polyurethane / polyacrylate hybrid resin emulsion according to claim 1, characterized in that, In step (1), the catalyst is selected from: dibutyltin dilaurate or triethylenediamine.

5. The synthesis method of the polyurethane / polyacrylate hybrid resin emulsion according to claim 1, characterized in that, In the diisocyanate of step (1), the aromatic diisocyanate is selected from: toluene diisocyanate, methylene diphenyl diisocyanate; the aliphatic or alicyclic diisocyanate is selected from: hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated MDI.

6. The synthesis method of the polyurethane / polyacrylate hybrid resin emulsion according to claim 1, wherein, In step (1), the chain extender is selected from ethylene glycol, propylene glycol, ethylenediamine or propylenediamine.

7. The synthesis method of the polyurethane / polyacrylate hybrid resin emulsion according to claim 1, characterized in that, Among the acrylate monomers described in step (2), the esters of acrylic acid and its homologues are selected from: methyl acrylate, n-butyl acrylate, methyl methacrylate; other monomers that can undergo free radical copolymerization reactions with acrylate monomers are selected from: acrylonitrile, styrene, vinyl acetate.

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