A method for preparing a bio-based aqueous acrylic secondary dispersion

Abstract

The application discloses a preparation method of a bio-based aqueous acrylic secondary dispersion, and comprises the following steps: adding propylene glycol butyl ether into a reaction kettle and heating at a constant temperature; uniformly mixing chitosan, styrene, butyl acrylate, isooctyl ester, methyl methacrylate, hydroxyethyl methacrylate, di-tert-butyl peroxide and an initiator to form a first mixed solution, and then adding the first mixed solution into the reaction kettle drop by drop; uniformly mixing methyl methacrylate, butyl acrylate, methyl methacrylate hydroxyethyl ester, acrylic acid, di-tert-butyl peroxide and a molecular regulator to obtain a second mixed solution, and then adding the second mixed solution into the reaction kettle drop by drop; adding di-tert-butyl peroxide into the reaction kettle and keeping warm; adding dopamine into the reaction kettle after the reaction kettle is cooled and stirred to obtain a pre-preparation; slowly adding distilled water and rapidly stirring, and then standing when the viscosity is the highest, and then adding the remaining distilled water and uniformly stirring to obtain an acrylic secondary dispersion.

Description

Technical Field

[0001] This invention belongs to the field of chemical coatings, specifically relating to a method for preparing a bio-based aqueous acrylic secondary dispersion. Background Technology

[0002] Waterborne two-component polyurethane coatings commonly use waterborne hydroxyl acrylic dispersions, which are classified into primary and secondary dispersions. Primary dispersions refer to hydroxyl-containing acrylic emulsions, mainly obtained through emulsion polymerization of acrylic monomers. These emulsions have the advantages of large particle size and being solvent-free, but their dispersion ability for curing agents is poor, resulting in a short application period and less than ideal coating performance and appearance. Secondary acrylic dispersions are obtained through solution polymerization of acrylate monomers, followed by neutralization and salt formation after removing most of the solvent, and finally dispersion in water. Compared to emulsion polymerization, secondary acrylic dispersions have smaller particle sizes, better compatibility with isocyanate curing agents, and the resulting cross-linked coatings have higher gloss and hardness. However, current secondary acrylic dispersions do not possess antibacterial properties. To address this, antibacterial agents are added to the secondary acrylic dispersions; however, incompatibility issues exist between the antibacterial agents and the acrylic materials in the secondary dispersion. Summary of the Invention

[0003] To address the problems in the prior art, the present invention provides a solution that solves the problem of poor antibacterial properties of existing dispersions. The invention utilizes the addition of chitosan to impart antibacterial properties to the dispersion, and disperses it throughout the entire system before polymerization to ensure the homogenization of the antibacterial properties.

[0004] To achieve the above technical objectives, the technical solution of the present invention is as follows:

[0005] A method for preparing a bio-based aqueous acrylic secondary dispersion includes the following steps:

[0006] Step 1: Add 58-71 parts of propylene glycol butyl ether to the reaction vessel and heat at a constant temperature to form a homogeneous liquid;

[0007] Step 2: Using a dropping vessel, 13-16 parts of chitosan, 23-28 parts of styrene, 73-90 parts of butyl acrylate, 30-36 parts of isooctyl acrylate, 123-150 parts of methyl methacrylate, 45-55 parts of hydroxyethyl methacrylate, 10-13 parts of di-tert-butyl peroxide, and 3-5 parts of initiator are mixed evenly to form a first mixture. Then, the first mixture is dropped into the reaction vessel.

[0008] Step 3: Mix 36-43 parts of methyl methacrylate, 29-36 parts of butyl acrylate, 18-22 parts of methyl methacrylate hydroxyethyl ester, 11.2-13.8 parts of acrylic acid, 2.5-3.5 parts of di-tert-butyl peroxide, and 0.8-1.2 parts of molecular regulator evenly to obtain a second mixture, and then add the second mixture dropwise into the reaction vessel;

[0009] Step 4: Add 0.4-0.6 parts of di-tert-butyl peroxide to the reactor and keep it at this temperature for 1.5 hours.

[0010] Step 5: After cooling the reactor, add 14-17 parts of dopamine and stir for 10-20 minutes to obtain the pre-prepared material;

[0011] Step 6: Slowly add distilled water and stir rapidly, and let it stand for 20 minutes when the viscosity is highest. Then add the remaining distilled water and stir at a constant speed to obtain a secondary dispersion of acrylic acid, in which the total amount of distilled water is 419-511 parts.

[0012] The temperature of the constant temperature heating in step 1 is 140℃, and the heating rate of the constant temperature heating is 10-20℃ / min.

[0013] The initiator in step 2 is a mixture of potassium persulfate and cerium ammonium nitrate, with a mass ratio of potassium persulfate to cerium ammonium nitrate of 3:1.

[0014] The dripping time in step 2 is 3-5 hours.

[0015] The molecular regulator used in step 3 is n-dodecyl mercaptan.

[0016] The mixing speed in step 3 is 300-500 r / min.

[0017] The dripping time in step 3 is 1.5-2 hours.

[0018] The insulation temperature in step 4 is 140℃.

[0019] The temperature after cooling in step 5 is below 110℃. Further, the temperature after cooling is 90-100℃.

[0020] The rapid stirring speed in step 6 is 1000-2000 r / min.

[0021] Furthermore, the chitosan used is modified chitosan. Chitosan, also known as deacetylated chitin, soluble chitin, and polyglucosamine, can generate positively charged cationic groups during the reaction. Although its surface still contains a large number of amino and hydroxyl groups, its water solubility is poor, making it difficult to form a homogeneous dispersion in an aqueous state. To solve this problem, the chitosan is modified to improve its solubility and ensure that it exhibits a certain degree of water solubility. The preparation method of the modified chitosan includes the following steps: a1, adding chitosan to acetic acid and stirring evenly to obtain a chitosan solution, wherein the concentration of chitosan in acetic acid is 100-300 g / L, and the stirring speed is 100-200 r / min; a2, adding cyclodextrin to the chitosan solution and sonicating. Disperse for 20-40 minutes, then evaporate the dispersion at a constant temperature to obtain a solid; the cyclodextrin added is 50-60% of the chitosan mass; the ultrasonic dispersion frequency is 70-80 kHz, and the temperature is 30℃; the constant temperature evaporation temperature is 70-80℃; a3, grind the solid to form a powder, then add the powder to distilled water and sonicate for 40-50 minutes; after centrifugation and filtration, spray dry the filtrate to obtain modified chitosan; at the same time, precipitate and recover unmodified chitosan, which can be used for subsequent modification processes; the grinding pressure is 0.3-0.4 MPa, and the temperature is 20-30℃; the concentration of the powder in distilled water is 100-400 g / L; the ultrasonic frequency is 60-80 kHz, and the temperature is 30-40℃. This process utilizes solubility characteristics to achieve the penetration and stabilization of chitosan in cyclodextrin, and uses the chitosan crystallization caused by concentration changes to ensure the deposition of chitosan in cyclodextrin. It also utilizes the difference in solubility in distilled water to recover chitosan residues, thereby obtaining modified chitosan with high stability and purity, reaching a purity of 95%.

[0022] As can be seen from the above description, the present invention has the following advantages:

[0023] 1. This invention solves the problem of poor antibacterial properties of existing dispersions by adding chitosan to impart antibacterial properties to the dispersion and dispersing it throughout the entire system before polymerization to ensure the homogenization of the antibacterial properties.

[0024] 2. This invention utilizes dopamine as a dopant, which not only enables infiltration polymerization under temperature conditions, improving the cohesive system of the material, but also allows the polydopamine formed by condensation polymerization to form a network structure under a charge system with chitosan, resulting in an excellent antibacterial system.

[0025] 3. This invention utilizes modified chitosan as a chitosan raw material. By modifying chitosan, the stability of chitosan within the material can be effectively improved, reducing the problem of pulverization. Detailed Implementation

[0026] The present invention will be described in detail with reference to the embodiments, but the claims of the present invention are not intended to limit the scope of the invention.

[0027] Example 1

[0028] A method for preparing a bio-based aqueous acrylic secondary dispersion includes the following steps:

[0029] Step 1: Add 58 parts of propylene glycol butyl ether to the reaction vessel and heat at a constant temperature to form a homogeneous liquid; the temperature of the constant temperature heating in Step 1 is 140℃, and the heating rate is 10℃ / min.

[0030] Step 2: Using a dropping vessel, 13 parts chitosan, 23 parts styrene, 73 parts butyl acrylate, 30 parts isooctyl acrylate, 123 parts methyl methacrylate, 45 parts hydroxyethyl methacrylate, 10 parts di-tert-butyl peroxide, and 3 parts initiator are mixed evenly to form a first mixture. The first mixture is then dropped into the reaction vessel. The initiator in Step 2 is a mixture of potassium persulfate and cerium ammonium nitrate, and the mass ratio of potassium persulfate to cerium ammonium nitrate is 3:1. The dropping time is 3 hours.

[0031] Step 3: Mix 36 parts of methyl methacrylate, 29 parts of butyl acrylate, 18 parts of methyl methacrylate hydroxyethyl ester, 11.2 parts of acrylic acid, 2.5 parts of di-tert-butyl peroxide, and 0.8 parts of molecular regulator evenly to obtain a second mixture. Then, add the second mixture dropwise to the reaction vessel. The molecular regulator in Step 3 is n-dodecyl mercaptan. The stirring speed for even mixing is 300 r / min, and the dropwise addition time is 1.5 h.

[0032] Step 4: Add 0.4 parts of di-tert-butyl peroxide to the reactor and keep it at a temperature of 140°C for 1.5 hours.

[0033] Step 5: After cooling the reactor, add 14 parts of dopamine and stir for 10 minutes to obtain the pre-prepared material;

[0034] Step 6: Slowly add distilled water and stir rapidly, and let it stand for 20 minutes when the viscosity is highest. Then add the remaining distilled water and stir at a constant speed to obtain a secondary dispersion of acrylic acid, in which the total amount of distilled water is 419 parts.

[0035] The temperature after cooling in step 5 is 90℃.

[0036] The rapid stirring speed in step 6 is 1000 r / min.

[0037] Example 2

[0038] A method for preparing a bio-based aqueous acrylic secondary dispersion includes the following steps:

[0039] Step 1: Add 71 parts of propylene glycol butyl ether to the reaction vessel and heat at a constant temperature to form a homogeneous liquid;

[0040] Step 2: Using a dropper, 16 parts of chitosan, 28 parts of styrene, 90 parts of butyl acrylate, 36 parts of isooctyl acrylate, 150 parts of methyl methacrylate, 55 parts of hydroxyethyl methacrylate, 13 parts of di-tert-butyl peroxide, and 5 parts of initiator are mixed evenly to form a first mixture. Then, the first mixture is added dropwise to the reaction vessel.

[0041] Step 3: Mix 43 parts of methyl methacrylate, 36 parts of butyl acrylate, 22 parts of methyl methacrylate hydroxyethyl ester, 13.8 parts of acrylic acid, 3.5 parts of di-tert-butyl peroxide, and 1.2 parts of molecular regulator evenly to obtain a second mixture, and then add the second mixture dropwise into the reaction vessel;

[0042] Step 4: Add 0.6 parts of di-tert-butyl peroxide to the reactor and keep it at this temperature for 1.5 hours.

[0043] Step 5: After cooling the reactor, add 17 parts of dopamine and stir for 20 minutes to obtain the pre-prepared material;

[0044] Step 6: Slowly add distilled water and stir rapidly, and let it stand for 20 minutes when the viscosity is highest. Then add the remaining distilled water and stir at a constant speed to obtain a secondary dispersion of acrylic acid, in which the total amount of distilled water is 511 parts.

[0045] The temperature of the constant temperature heating in step 1 is 140℃, and the heating rate of the constant temperature heating is 20℃ / min.

[0046] The initiator in step 2 is a mixture of potassium persulfate and cerium ammonium nitrate, with a mass ratio of potassium persulfate to cerium ammonium nitrate of 3:1.

[0047] The dripping time in step 2 is 5 hours.

[0048] The molecular regulator used in step 3 is n-dodecyl mercaptan.

[0049] The mixing speed in step 3 is 500 r / min.

[0050] The dripping time in step 3 is 2 hours.

[0051] The insulation temperature in step 4 is 140℃.

[0052] The temperature after cooling in step 5 is 100℃.

[0053] The rapid stirring speed in step 6 is 2000 r / min.

[0054] Example 3

[0055] A method for preparing a bio-based aqueous acrylic secondary dispersion includes the following steps:

[0056] Step 1: Add 65 parts of propylene glycol butyl ether to the reaction vessel and heat at a constant temperature to form a homogeneous liquid;

[0057] Step 2: Using a dropper, 15 parts chitosan, 25 parts styrene, 85 parts butyl acrylate, 33 parts isooctyl acrylate, 145 parts methyl methacrylate, 50 parts hydroxyethyl methacrylate, 1 part di-tert-butyl peroxide, and 4 parts initiator are mixed evenly to form a first mixture. Then, the first mixture is added dropwise to the reaction vessel.

[0058] Step 3: Mix 40 parts of methyl methacrylate, 33 parts of butyl acrylate, 20 parts of methyl methacrylate hydroxyethyl ester, 12.3 parts of acrylic acid, 3 parts of di-tert-butyl peroxide, and 1 part of molecular regulator evenly to obtain a second mixture. Then, add the second mixture dropwise into the reaction vessel.

[0059] Step 4: Add 0.5 parts of di-tert-butyl peroxide to the reactor and keep it at this temperature for 1.5 hours.

[0060] Step 5: After cooling the reactor, add 15 parts of dopamine and stir for 10-20 minutes to obtain the pre-prepared material;

[0061] Step 6: Slowly add distilled water and stir rapidly, and let it stand for 20 minutes when the viscosity is highest. Then add the remaining distilled water and stir at a constant speed to obtain a secondary dispersion of acrylic acid, in which the total amount of distilled water is 500 parts.

[0062] The temperature of the constant temperature heating in step 1 is 140℃, and the heating rate of the constant temperature heating is 15℃ / min.

[0063] The initiator in step 2 is a mixture of potassium persulfate and cerium ammonium nitrate, with a mass ratio of potassium persulfate to cerium ammonium nitrate of 3:1.

[0064] The dripping time in step 2 is 4 hours.

[0065] The molecular regulator used in step 3 is n-dodecyl mercaptan.

[0066] The mixing speed in step 3 is 400 r / min.

[0067] The dripping time in step 3 is 1.5 hours.

[0068] The insulation temperature in step 4 is 140℃.

[0069] The temperature after cooling in step 5 is 95℃.

[0070] The rapid stirring speed in step 6 is 1500 r / min.

[0071] Example 4

[0072] A method for preparing a bio-based aqueous acrylic secondary dispersion includes the following steps:

[0073] Step 1: Add 58 parts of propylene glycol butyl ether to the reaction vessel and heat at a constant temperature to form a homogeneous liquid;

[0074] Step 2: Using a dropper, 13 parts chitosan, 23 parts styrene, 73 parts butyl acrylate, 30 parts isooctyl acrylate, 123 parts methyl methacrylate, 45 parts hydroxyethyl methacrylate, 10 parts di-tert-butyl peroxide, and 3 parts initiator are mixed evenly to form a first mixture. Then, the first mixture is added dropwise to the reaction vessel.

[0075] Step 3: Mix 36 parts of methyl methacrylate, 29 parts of butyl acrylate, 18 parts of methyl methacrylate hydroxyethyl ester, 11.2 parts of acrylic acid, 2.5 parts of di-tert-butyl peroxide, and 0.8 parts of molecular regulator evenly to obtain a second mixture, and then add the second mixture dropwise into the reaction vessel;

[0076] Step 4: Add 0.4 parts of di-tert-butyl peroxide to the reactor and keep it at this temperature for 1.5 hours.

[0077] Step 5: After cooling the reactor, add 14 parts of dopamine and stir for 10 minutes to obtain the pre-prepared material;

[0078] Step 6: Slowly add distilled water and stir rapidly, and let it stand for 20 minutes when the viscosity is highest. Then add the remaining distilled water and stir at a constant speed to obtain a secondary dispersion of acrylic acid, in which the total amount of distilled water is 419 parts.

[0079] The temperature of the constant temperature heating in step 1 is 140℃, and the heating rate of the constant temperature heating is 10℃ / min.

[0080] The initiator in step 2 is a mixture of potassium persulfate and cerium ammonium nitrate, with a mass ratio of potassium persulfate to cerium ammonium nitrate of 3:1.

[0081] The dripping time in step 2 is 3 hours.

[0082] The molecular regulator used in step 3 is n-dodecyl mercaptan.

[0083] The mixing speed in step 3 is 300 r / min.

[0084] The dripping time in step 3 is 1.5 hours.

[0085] The insulation temperature in step 4 is 140℃.

[0086] The temperature after cooling in step 5 is 90℃.

[0087] The rapid stirring speed in step 6 is 1000 r / min.

[0088] The chitosan used is modified chitosan, and the preparation method of the modified chitosan includes the following steps: a1, adding chitosan to acetic acid and stirring evenly to obtain a chitosan solution, wherein the concentration of chitosan in acetic acid is 100 g / L, and the stirring speed is 100 r / min; a2, adding cyclodextrin to the chitosan solution and ultrasonically dispersing for 20 min, then evaporating the dispersion at a constant temperature to obtain a solid; the amount of cyclodextrin added is 50% of the mass of chitosan, and the ultrasonic dispersion frequency is [missing information]. The temperature is 30℃ and the constant temperature evaporation temperature is 70℃; a3, the solid is ground to form powder, and then the powder is added to distilled water and sonicated for 40 minutes. After centrifugation and filtration, the filtrate is spray-dried to obtain modified chitosan. At the same time, unmodified chitosan is precipitated and recovered, which can be used for subsequent modification processes. The grinding pressure is 0.3MPa and the temperature is 20℃; the concentration of the powder in distilled water is 100g / L, and the ultrasonic frequency is 60kHz and the temperature is 30℃.

[0089] Example 5

[0090] A method for preparing a bio-based aqueous acrylic secondary dispersion includes the following steps:

[0091] Step 1: Add 71 parts of propylene glycol butyl ether to the reaction vessel and heat at a constant temperature to form a homogeneous liquid;

[0092] Step 2: Using a dropper, 16 parts of chitosan, 28 parts of styrene, 90 parts of butyl acrylate, 36 parts of isooctyl acrylate, 150 parts of methyl methacrylate, 55 parts of hydroxyethyl methacrylate, 13 parts of di-tert-butyl peroxide, and 5 parts of initiator are mixed evenly to form a first mixture. Then, the first mixture is added dropwise to the reaction vessel.

[0093] Step 3: Mix 43 parts of methyl methacrylate, 36 parts of butyl acrylate, 22 parts of methyl methacrylate hydroxyethyl ester, 13.8 parts of acrylic acid, 3.5 parts of di-tert-butyl peroxide, and 1.2 parts of molecular regulator evenly to obtain a second mixture, and then add the second mixture dropwise into the reaction vessel;

[0094] Step 4: Add 0.6 parts of di-tert-butyl peroxide to the reactor and keep it at this temperature for 1.5 hours.

[0095] Step 5: After cooling the reactor, add 17 parts of dopamine and stir for 20 minutes to obtain the pre-prepared material;

[0096] Step 6: Slowly add distilled water and stir rapidly, and let it stand for 20 minutes when the viscosity is highest. Then add the remaining distilled water and stir at a constant speed to obtain a secondary dispersion of acrylic acid, in which the total amount of distilled water is 511 parts.

[0097] The temperature of the constant temperature heating in step 1 is 140℃, and the heating rate of the constant temperature heating is 20℃ / min.

[0098] The initiator in step 2 is a mixture of potassium persulfate and cerium ammonium nitrate, with a mass ratio of potassium persulfate to cerium ammonium nitrate of 3:1.

[0099] The dripping time in step 2 is 5 hours.

[0100] The molecular regulator used in step 3 is n-dodecyl mercaptan.

[0101] The mixing speed in step 3 is 500 r / min.

[0102] The dripping time in step 3 is 2 hours.

[0103] The insulation temperature in step 4 is 140℃.

[0104] The temperature after cooling in step 5 is 100℃.

[0105] The rapid stirring speed in step 6 is 2000 r / min.

[0106] The chitosan used is modified chitosan, and the preparation method of the modified chitosan includes the following steps: a1, adding chitosan to acetic acid and stirring evenly to obtain a chitosan solution, wherein the concentration of chitosan in acetic acid is 300 g / L, and the stirring speed is 200 r / min; a2, adding cyclodextrin to the chitosan solution and ultrasonically dispersing for 40 min, then evaporating the dispersion at a constant temperature to obtain a solid; the amount of cyclodextrin added is 60% of the mass of chitosan, and the ultrasonic dispersion frequency is [missing information]. The temperature is 30°C and the constant temperature evaporation temperature is 80°C. A3, the solid is ground to form powder, then the powder is added to distilled water and ultrasonicated for 50 minutes. After centrifugation and filtration, the filtrate is spray-dried to obtain modified chitosan. Simultaneously, unmodified chitosan is precipitated and recovered for subsequent modification processes. The grinding pressure is 0.4 MPa and the temperature is 30°C. The concentration of the powder in distilled water is 400 g / L. The ultrasonic frequency is 80 kHz and the temperature is 40°C.

[0107] Example 6

[0108] A method for preparing a bio-based aqueous acrylic secondary dispersion includes the following steps:

[0109] Step 1: Add 65 parts of propylene glycol butyl ether to the reaction vessel and heat at a constant temperature to form a homogeneous liquid;

[0110] Step 2: Using a dropper, 15 parts chitosan, 25 parts styrene, 85 parts butyl acrylate, 33 parts isooctyl acrylate, 145 parts methyl methacrylate, 50 parts hydroxyethyl methacrylate, 1 part di-tert-butyl peroxide, and 4 parts initiator are mixed evenly to form a first mixture. Then, the first mixture is added dropwise to the reaction vessel.

[0111] Step 3: Mix 40 parts of methyl methacrylate, 33 parts of butyl acrylate, 20 parts of methyl methacrylate hydroxyethyl ester, 12.3 parts of acrylic acid, 3 parts of di-tert-butyl peroxide, and 1 part of molecular regulator evenly to obtain a second mixture. Then, add the second mixture dropwise into the reaction vessel.

[0112] Step 4: Add 0.5 parts of di-tert-butyl peroxide to the reactor and keep it at this temperature for 1.5 hours.

[0113] Step 5: After cooling the reactor, add 15 parts of dopamine and stir for 10-20 minutes to obtain the pre-prepared material;

[0114] Step 6: Slowly add distilled water and stir rapidly, and let it stand for 20 minutes when the viscosity is highest. Then add the remaining distilled water and stir at a constant speed to obtain a secondary dispersion of acrylic acid, in which the total amount of distilled water is 500 parts.

[0115] The temperature of the constant temperature heating in step 1 is 140℃, and the heating rate of the constant temperature heating is 15℃ / min.

[0116] The initiator in step 2 is a mixture of potassium persulfate and cerium ammonium nitrate, with a mass ratio of potassium persulfate to cerium ammonium nitrate of 3:1.

[0117] The dripping time in step 2 is 4 hours.

[0118] The molecular regulator used in step 3 is n-dodecyl mercaptan.

[0119] The mixing speed in step 3 is 400 r / min.

[0120] The dripping time in step 3 is 1.5 hours.

[0121] The insulation temperature in step 4 is 140℃.

[0122] The temperature after cooling in step 5 is 95℃.

[0123] The rapid stirring speed in step 6 is 1500 r / min.

[0124] The chitosan used is modified chitosan, and the preparation method of the modified chitosan includes the following steps: a1, adding chitosan to acetic acid and stirring evenly to obtain a chitosan solution, wherein the concentration of chitosan in acetic acid is 200 g / L, and the stirring speed is 150 r / min; a2, adding cyclodextrin to the chitosan solution and ultrasonically dispersing for 30 min, and then evaporating the dispersion at a constant temperature to obtain a solid; wherein the amount of cyclodextrin added is 55% of the mass of chitosan, and the ultrasonic dispersion frequency is [missing information]. The temperature is 30°C and the constant temperature evaporation temperature is 75°C. A3, the solid is ground to form powder, then the powder is added to distilled water and sonicated for 45 minutes. After centrifugation and filtration, the filtrate is spray-dried to obtain modified chitosan. Simultaneously, unmodified chitosan is precipitated and recovered for subsequent modification processes. The grinding pressure is 0.3 MPa and the temperature is 25°C. The concentration of the powder in distilled water is 300 g / L. The sonication frequency is 70 kHz and the temperature is 35°C.

[0125] Comparative Example 1

[0126] A method for preparing an aqueous acrylic secondary dispersion, obtained by means of method CN201710562230.0.

[0127] Comparative Example 2

[0128] A method for preparing an aqueous acrylic secondary dispersion is the same as in Example 3, except that chitosan and dopamine are not used.

[0129] Comparative Example 3

[0130] A method for preparing an aqueous acrylic secondary dispersion is the same as in Example 3, except that chitosan is not used.

[0131] Comparative Example 4

[0132] A method for preparing an aqueous acrylic secondary dispersion is the same as in Example 3, except that dopamine is not used.

[0133] Performance testing (indicating that the product prepared by this method has superior properties).

[0134]

[0135]

[0136] It is understood that the above detailed description of the present invention is for illustrative purposes only and is not intended to limit the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention to achieve the same technical effects; as long as the usage requirements are met, they are all within the protection scope of the present invention.

Claims

1. A method for preparing a bio-based aqueous acrylic secondary dispersion, characterized in that: Includes the following steps: Step 1: Add 58-71 parts of propylene glycol butyl ether to the reaction vessel and heat at a constant temperature to form a homogeneous liquid; Step 2: Using a dropping vessel, 13-16 parts of chitosan, 23-28 parts of styrene, 73-90 parts of butyl acrylate, 30-36 parts of isooctyl acrylate, 123-150 parts of methyl methacrylate, 45-55 parts of hydroxyethyl methacrylate, 10-13 parts of di-tert-butyl peroxide, and 3-5 parts of initiator are mixed evenly to form a first mixture. Then, the first mixture is dropped into the reaction vessel. Step 3: Mix 36-43 parts of methyl methacrylate, 29-36 parts of butyl acrylate, 18-22 parts of methyl methacrylate hydroxyethyl ester, 11.2-13.8 parts of acrylic acid, 2.5-3.5 parts of di-tert-butyl peroxide, and 0.8-1.2 parts of molecular regulator evenly to obtain a second mixture, and then add the second mixture dropwise into the reaction vessel; Step 4: Add 0.4-0.6 parts of di-tert-butyl peroxide to the reactor and keep it at this temperature for 1.5 hours. Step 5: After cooling the reactor, add 14-17 parts of dopamine and stir for 10-20 minutes to obtain the pre-prepared material; Step 6: Slowly add distilled water and stir rapidly, and let it stand for 20 minutes when the viscosity is highest. Then add the remaining distilled water and stir at a constant speed to obtain a secondary dispersion of acrylic acid, in which the total amount of distilled water is 419-511 parts.

2. The method for preparing a bio-based aqueous acrylic secondary dispersion according to claim 1, characterized in that: The temperature of the constant temperature heating in step 1 is 140℃, and the heating rate of the constant temperature heating is 10-20℃ / min.

3. The method for preparing a bio-based aqueous acrylic secondary dispersion according to claim 1, characterized in that: The initiator in step 2 is a mixture of potassium persulfate and cerium ammonium nitrate, with a mass ratio of potassium persulfate to cerium ammonium nitrate of 3:

1.

4. The method for preparing a bio-based aqueous acrylic secondary dispersion according to claim 1, characterized in that: The dripping time in step 2 is 3-5 hours.

5. The method for preparing a bio-based aqueous acrylic secondary dispersion according to claim 1, characterized in that: The molecular regulator used in step 3 is n-dodecyl mercaptan.

6. The method for preparing a bio-based aqueous acrylic secondary dispersion according to claim 1, characterized in that: The mixing speed in step 3 is 300-500 r / min.

7. The method for preparing a bio-based aqueous acrylic secondary dispersion according to claim 1, characterized in that: The dripping time in step 3 is 1.5-2 hours.

8. The method for preparing a bio-based aqueous acrylic secondary dispersion according to claim 1, characterized in that: The insulation temperature in step 4 is 140℃.

9. The method for preparing a bio-based aqueous acrylic secondary dispersion according to claim 1, characterized in that: The temperature after cooling in step 5 is below 110℃. Further, the temperature after cooling is 90-100℃.

10. The method for preparing a bio-based aqueous acrylic secondary dispersion according to claim 1, characterized in that: The rapid stirring speed in step 6 is 1000-2000 r / min.

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