Preparation method of water-based acrylic acid suspension thickening emulsion

Abstract

The invention discloses a preparation method of a water-based acrylic acid suspension thickening emulsion, which comprises the following steps: when the residual monomer content of a soft monomer is 200-1000ppm in the preparation process, supplementing the soft monomer into a reaction kettle, and continuing to react. By adopting the method, the production stability and the product performance are fully balanced, the industrial production repeatability of the obtained emulsion is good, and meanwhile, the thickening agent prepared by the process has excellent suspension thickening performance and transparency.

Description

Technical Field

[0001] The invention relates to the field of thickener preparation technology, and in particular to a preparation method and application of an aqueous acrylic acid suspension thickening emulsion. Background Art

[0002] As the quality of life continues to improve, people have put forward more new requirements for personal cleaning products. For example, in order to pursue a more beautiful appearance, they will require the addition of elements such as pearl powder, petals, soft beads or walnut particles. Suspension thickeners, as a rheology regulator widely used in shampoo, shower gel and other care products, play a vital role in the field of washing and care. With excellent compatibility and good transparency, it can be compounded with anionic, nonionic and zwitterionic surfactants, as well as commonly used additives and conditioners, to make shampoo, shower gel and other cleaning products. In addition, suspension thickeners can also suspend colored frosted particles and show broad application potential in products such as creams and essences.

[0003] Most of the commonly used suspension thickeners in skin care products are acrylic copolymers, such as liquid carbomer, which are anionic polymers. They can give skin care products excellent suspension and thickening properties, ensuring that the ingredients in the product can be evenly suspended and not easily deposited. However, the common suspension thickeners on the market often electrostatically bond with the cationic conditioning agents in the formula when used, resulting in a significant reduction in the conditioning effect of the formula. At the same time, the addition of high molecular copolymers will also affect the transparency of the formula to a certain extent.

[0004] In order to solve this problem, patent CN103772625A discloses an antifreeze type acrylic suspension thickening emulsion, which improves the suspension thickening performance by introducing hydrophobically modified surface-active monomers while also having good antifreeze properties. However, it still has the above-mentioned defects, that is, it will lose too much transparency while ensuring its basic suspension thickening performance.

[0005] Patents CN103772625A and CN107641167A both improve suspension thickening by introducing long-chain hydrophobic monomers. However, since such long-chain alkyl monomers are too hydrophobic and have low solubility in water, they are difficult to migrate through the aqueous phase into the latex particles for polymerization during emulsion polymerization and exist in the chain segments. Although the suspension thickening can be improved, the transparency loss is large and the emulsion polymerization is obviously unstable. In addition, since large-scale production control is more difficult, the existing industrial production process has large fluctuations and is difficult to achieve stable production. How to produce a stable suspension thickener that meets performance requirements has become an urgent problem to be solved. Summary of the invention

[0006] In order to solve the problems of poor transparency and suspension performance of aqueous acrylic suspension thickener emulsion and unstable industrial production, the present invention aims to provide a method for preparing an aqueous acrylic suspension thickening emulsion, wherein the obtained emulsion has high transparency and good suspension performance, high batch stability during industrial production, stable performance, and can achieve a perfect balance between performance and industrial production.

[0007] To achieve the above objectives, the present invention adopts the following technical solutions.

[0008] A method for preparing an aqueous acrylic acid suspension thickening emulsion comprises the following steps:

[0009] (1) Add water to the reaction kettle, heat it to 70-95°C, and add emulsifier I and additives to the bottom of the kettle;

[0010] (2) At 70-95° C., initiator I is added to the reactor. After 5-10 minutes, pre-emulsion, initiator II, and emulsifier II are simultaneously added to the reactor. When the amount of pre-emulsion added is 75%-95% of its mass, chain transfer agent is added to the pre-emulsion. After stirring for 5-15 minutes, the pre-emulsion is continued to be added until all the pre-emulsion is added. The total addition time is 120-240 minutes.

[0011] (3) Keep warm for 30-90 minutes, cool to 65-80°C, detect the residual monomer of soft monomer during the keeping warm process, add soft monomer to the reactor when the residual monomer of soft monomer is 200-1000ppm, stir for 5-20 minutes, add oxidant I and reductant I, and the interval between adding oxidant I and reductant I is less than 5 minutes. Keep warm for 30-60 minutes, then start adding oxidant II and reductant II, which takes 60-120 minutes. After the addition is completed, keep warm for 60-120 minutes.

[0012] The above process is all carried out in the polymerization kettle. After the heat preservation is completed, the temperature is lowered to 50-60°C, the kettle is turned, a defoamer and a preservative are added, and the material is filtered out.

[0013] Preferably, in the preparation method, the amount of each component added is:

[0014] Pre-emulsion 220-630 parts by mass, preferably 270-490 parts by mass,

[0015] Emulsifier 2-10 parts by mass, preferably 3-9 parts by mass,

[0016] 0.3-3 parts by mass of auxiliary agent, preferably 0.5-2 parts by mass,

[0017] Chain transfer agent 0.1-3 parts by mass, preferably 0.2-1.5 parts by mass,

[0018] Initiator 0.1-2 parts by mass, preferably 0.1-1.5 parts by mass,

[0019] Oxidant 0.5-6 parts by mass, preferably 0.8-4 parts by mass,

[0020] 0.4-2 parts by mass of reducing agent, preferably 0.5-1.5 parts by mass,

[0021] Defoaming agent 0-1 mass part, preferably 0.2-0.8 mass part,

[0022] 0-4 parts by mass, preferably 1.5-3.5 parts by mass, of preservatives;

[0023] 340-775 parts by mass of water, preferably 450-750 parts by mass;

[0024] The total mass of the above components is 1000 parts.

[0025] The amount of emulsifier added refers to the total amount of emulsifier I and emulsifier II. The addition ratio of emulsifier I and emulsifier II can be selected according to the common knowledge of those skilled in the art, such as the mass ratio of emulsifier I to emulsifier II is 1:20-20:1.

[0026] The amount of initiator added refers to the total amount of initiator I and initiator II. The addition ratio of initiator I and initiator II can be selected according to the common knowledge of those skilled in the art, such as the mass ratio of initiator I and initiator II is 1:20-20:1.

[0027] The amount of oxidant added refers to the total amount of oxidant I and oxidant II. The addition ratio of oxidant I and oxidant II can be selected according to the common knowledge of those skilled in the art, such as the mass ratio of oxidant I and oxidant II is 1:20-20:1.

[0028] The amount of reducing agent added refers to the total amount of reducing agent I and reducing agent II. The addition ratio of reducing agent I and reducing agent II can be selected according to the common knowledge of those skilled in the art, such as the mass ratio of reducing agent I and reducing agent II is 1:20-20:1.

[0029] In the present invention, the emulsifier I and the emulsifier II are independently selected from one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, alkyl polyoxyethylene ether, sodium p-styrene sulfonate, fatty alcohol polyoxyethylene ether and its salts and fatty alcohol ether phosphate and its salts, preferably sodium dodecyl sulfate and sodium p-styrene sulfonate. In step (1) of the present invention, the auxiliary agent is one or more of alkali metal carbonate, alkali metal bicarbonate, alcohol, preferably one or more of sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, methanol, and ethanol.

[0030] In step (2) of the present invention, the initiator is a peroxide, preferably one or more of ammonium persulfate, sodium persulfate, potassium persulfate, cumene hydroperoxide, and tert-butyl hydroperoxide.

[0031] In step (2) of the present invention, the pre-emulsion comprises the following components, calculated based on 100 parts by mass of the total mass of the pre-emulsion:

[0032] 18-40 parts by mass of hard monomer, preferably 20-35 parts by mass;

[0033] Soft monomer 45-65 parts by mass, preferably 45-58 parts by mass;

[0034] Functional monomer 0-3 parts by mass, preferably 0-1.5 parts by mass;

[0035] Emulsifier III 0-1.2 parts by mass, preferably 0-1 parts by mass;

[0036] Water: 10-30 parts by mass, preferably 13-27 parts by mass.

[0037] The method for preparing the pre-emulsion comprises the following steps: adding water and an emulsifier into a pre-emulsification kettle 1, stirring evenly, and then sequentially adding a soft monomer, an optional functional monomer, and a hard monomer, and stirring.

[0038] The emulsifier III in the pre-emulsion is one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, alkyl polyoxyethylene ether, sodium p-styrene sulfonate, fatty alcohol polyoxyethylene ether and its salts, and fatty alcohol ether phosphate and its salts.

[0039] The hard monomer in the pre-emulsion comprises one or more of styrene, methacrylic acid, acrylic acid, and methyl methacrylate, preferably methacrylic acid and methyl methacrylate.

[0040] The soft monomer in the pre-emulsion includes one or more of isooctyl acrylate, butyl acrylate, ethyl acrylate, isooctyl methacrylate, 2-ethylhexyl acrylate, and lauryl methacrylate.

[0041] The functional monomers in the pre-emulsion include one or more of hydroxyethyl acrylate, β-acryloxypropionic acid, diallyl phthalate, allyl methacrylate, ethylene glycol dimethacrylate, and 1,3-butanediol dimethacrylate.

[0042] In step (2) of the present invention, the chain transfer agent is one or more of n-dodecyl mercaptan, butyl mercapto, mercaptopropionic acid, and mercaptoethanol.

[0043] In step (3) of the present invention, the amount of the soft monomer added is 0.5%-10% by weight of the total monomers, preferably 0.5%-5%.

[0044] In step (3) of the present invention, the soft monomer is added all at once or quickly added within 5 minutes.

[0045] In step (3) of the present invention, the oxidant I is added at one time or quickly added within 5 minutes, and the reducing agent solution I is added at one time or quickly added within 5 minutes. In step (3) of the present invention, the initiator I and the initiator II are independently selected from peroxides, preferably selected from one or more of sodium persulfate, ammonium persulfate, tert-butyl hydroperoxide, cumene hydroperoxide, and hydrogen peroxide, preferably tert-butyl hydroperoxide.

[0046] In step (3) of the present invention, the reducing agent I and the reducing agent II are independently selected from one or more of sodium pyrosulfite, disodium pyrosulfite, ascorbic acid, and bleaching powder, preferably ascorbic acid.

[0047] In step (3) of the present invention, the defoaming agent is one or more of a silicone defoaming agent, a mineral oil defoaming agent, and a polyether defoaming agent, preferably a silicone defoaming agent, such as one or more of Evonik Degussa Tego1488, Tego825, BYK028, and BYK024, preferably Evonik Degussa Tego-825 and / or Tego-1488.

[0048] In step (3) of the present invention, the preservative is one or more of triazine preservatives, bisoxazolinidine preservatives, isothiazolinone preservatives, and broad-spectrum preservatives, preferably a broad-spectrum preservative, such as PHCG preservative.

[0049] The solid content of the aqueous acrylic acid suspension thickening emulsion of the invention is 25%-40% and the average particle size is 90-150nm.

[0050] In the present application, the hard monomer and the soft monomer are designed with corresponding differences in the reactivity ratio to achieve a large amount of acid distribution in the inner layer, and the acid concentration is designed to gradually decrease from the inside to the outside, ensuring that the high internal osmotic pressure is easier to absorb water and swell, and the water retention is stronger. At the same time, this method can avoid abnormal fluctuations caused by other complex process operations.

[0051] This formula inserts thiol into the outer layer to facilitate the entry of alkali into the interior during neutralization. Internal neutralization forms a high osmotic pressure, and the particles absorb water and swell, thereby reducing the transparency of the latex particles while instantly and significantly increasing the viscosity of the thickener.

[0052] In the process of industrial production, due to the amplification of the reaction vessel, the effect of three transmissions and one reaction is far worse than that of the laboratory test, which will cause the reaction structure to deviate from the expectation, and the internal acid cannot be completely wrapped, which will eventually lead to large fluctuations in product performance and fail to provide customers with stable products. Therefore, the formula uses a certain amount of soft monomers to perform violent polymerization in the outer layer by adjusting the process to achieve all-round wrapping of the internal acid. And the amount of wrapping is strictly controlled. If the amount of the soft monomer wrapped is too little, the internal acid is exposed to the outside and cannot be completely wrapped, the hydrophilic chain segment stretches too much, and the latex particle sphere morphology breaks, although it will cause the viscosity to increase significantly, but it is impossible to provide good suspension when finally applied. If the amount of soft monomer wrapped is too much and the shell is too thick, it will cause the latex particle sphere morphology to be unable to expand after neutralization, and it is impossible to have good suspension, and there are more external hydrophobic monomers, resulting in poor transparency of the finished product.

[0053] In summary, the present invention simplifies the process route and improves industrial repeatability while ensuring excellent transparency and suspension through a special production process combined with an ingenious overall formula design, thereby solving the problem of fluctuations in industrial production operations and performance. DETAILED DESCRIPTION

[0054] The present invention is further illustrated by the following examples. In the following examples, parts are by weight unless otherwise specified.

[0055] Table 1 Raw materials used to prepare acrylic suspension thickener emulsion

[0056] Abbreviation Chemical Type MMA Methyl Methacrylate EA Ethyl acrylate BA Butyl acrylate EHA 2-Ethylhexyl acrylate AA acrylic acid MAA Methacrylic acid APS Ammonium Persulfate SDS Sodium Lauryl Sulfate SSS Sodium p-styrene sulfonate ALMA Allyl methacrylate DAP Diallyl phthalate N-DM n-dodecanethiol NaHCO3 Sodium bicarbonate AE Ethanol T-BHP Tert-Butyl Hydroperoxide IAA Erythorbic Acid Tego825 Deco Defoamer PHCG Phenoxyethanol DIW Deionized water

[0057] Example 1: Emulsion 1-1

[0058] Pre-emulsion preparation:

[0059] Add 0.8 parts of SSS and 3.5 parts of SDS to 80 parts of deionized water and stir for 30 minutes. Add 70 parts of MAA, 6 parts of AA, 116.5 parts of EA, 28 parts of EHA and 3 parts of DAP to the pre-emulsification kettle and stir thoroughly.

[0060] Weigh 0.5 parts of ammonium persulfate APS and dissolve it in 10 parts of deionized water DIW to prepare initiator solution I;

[0061] Weigh 0.9 parts of ammonium persulfate APS, 0.8 parts of SSS, and 2 parts of SDS, and dissolve them in 40 parts of deionized water DIW to prepare initiator solution II;

[0062] Add 540 parts of deionized water to the reactor, heat to 83-88°C, add 1.5 parts of SDS, 1.5 parts of anhydrous ethanol, and 0.5 parts of NaHCO3. Add the initiator solution I to the reactor, and after 3 minutes, add the pre-emulsion (85% of the total mass) and the initiator solution II, control the reaction temperature at 85-89°C, and uniformly add for 120 minutes. When the addition reaches 102 minutes, stop the addition, add 0.8 parts by mass of NDM to the pre-emulsion, stir for 10 minutes, and continue to add until the addition of the pre-emulsion is completed, and keep warm for 60 minutes.

[0063] 3 parts of TBHP dissolved in 15 parts of deionized water are weighed to prepare oxidant solution I; 4 parts of TBHP dissolved in 20 parts of deionized water are weighed to prepare oxidant solution II;

[0064] Weigh 1.5 parts of IAA dissolved in 15 parts of deionized water to prepare reducing agent solution I; weigh 2 parts of IAA dissolved in 20 parts of deionized water to prepare reducing agent solution II;

[0065] When the residual EA in the polymerization kettle is detected to be 550ppm, the polymerization kettle is rapidly cooled to 75°C, 3.7 parts by mass of EA is quickly added into the reactor, and stirred for 5 minutes. Oxidant solution I and reductant solution I are quickly added thereto in sequence, and the interval between the addition of the two is less than 5 minutes. Keep warm for 60 minutes. Start to drop oxidant solution II and reductant solution II simultaneously, drop for 60 minutes, and keep warm for 60 minutes after the drop is completed. Cool down to less than 50°C, add 0.5 parts by mass of Tego825 defoamer and 2 parts by mass of PHCG dissolved in 7 parts of deionized water, add water to adjust the solid content to 30%, and filter the material. Emulsion 1-1 is obtained.

[0066] Example 2: Emulsion 1-2

[0067] Pre-emulsion preparation:

[0068] Add 0.8 parts of SSS and 3.5 parts of SDS to 80 parts of deionized water and stir for 30 minutes. Add 53.5 parts of MAA, 5.5 parts of AA, 131 parts of EA, 30.5 parts of EHA and 3 parts of DAP to the pre-emulsification kettle and stir thoroughly.

[0069] Weigh 0.5 parts of ammonium persulfate APS and dissolve it in 10 parts of deionized water DIW to prepare initiator solution I;

[0070] Weigh 0.9 parts of ammonium persulfate APS, 0.8 parts of SSS, and 2 parts of SDS, and dissolve them in 40 parts of deionized water DIW to prepare initiator solution II;

[0071] Add 540 parts of deionized water to the reactor, heat to 83-88°C, add 1.5 parts of SDS, 1.5 parts of anhydrous ethanol, and 0.5 parts of NaHCO3. Add initiator solution I to the reactor, and after 3 minutes, add pre-emulsion and initiator solution II, control the reaction temperature at 85-89°C, and uniformly add for 120 minutes. When the addition reaches 102 minutes, stop adding, add 0.8 parts by mass of NDM to the pre-emulsion, stir for 10 minutes, and continue to add until the addition is completed, and keep warm for 60 minutes.

[0072] 3 parts of TBHP dissolved in 15 parts of deionized water are weighed to prepare oxidant solution I; 4 parts of TBHP dissolved in 20 parts of deionized water are weighed to prepare oxidant solution II;

[0073] Weigh 1.5 parts of IAA dissolved in 15 parts of deionized water to prepare reducing agent solution I; weigh 2 parts of IAA dissolved in 20 parts of deionized water to prepare reducing agent solution II;

[0074] When the residual EA in the polymerization kettle is detected to be 250ppm, the polymerization kettle is rapidly cooled to 75°C, 3.7 parts by mass of EA are quickly added into the reactor, and stirred for 5 minutes. Oxidant solution I and reductant solution I are quickly added therein in sequence, and the interval between the addition of the two is less than 5 minutes. Keep warm for 60 minutes. Start to drop oxidant solution II and reductant solution II simultaneously, drop for 60 minutes, and keep warm for 60 minutes after the drop is completed. Cool down to less than 50°C, add 0.5 parts by mass of Tego825 defoamer and 2 parts by mass of PHCG dissolved in 7 parts of deionized water, add water to adjust the solid content to 30%, and filter the material. Emulsion 1-2 is obtained.

[0075] Example 3: Emulsion 1-3

[0076] Pre-emulsion preparation:

[0077] Add 0.8 parts of SSS and 3.5 parts of SDS to 80 parts of deionized water and stir for 30 minutes. Add 89 parts of MAA, 6.5 parts of AA, 99 parts of EA, 26 parts of EHA, 2 parts of DAP and 1 part of ALMA to the pre-emulsification kettle and stir thoroughly.

[0078] Weigh 0.5 parts of ammonium persulfate APS and dissolve it in 10 parts of deionized water DIW to prepare initiator solution I;

[0079] Weigh 0.9 parts of ammonium persulfate APS, 0.8 parts of SSS, and 2 parts of SDS, and dissolve them in 40 parts of deionized water DIW to prepare initiator solution II;

[0080] Add 540 parts of deionized water to the reactor, heat to 83-88°C, add 1.5 parts of SDS, 1.5 parts of anhydrous ethanol, and 0.5 parts of NaHCO3. Add initiator solution I to the reactor, and after 3 minutes, add pre-emulsion and initiator solution II, control the reaction temperature at 85-89°C, and uniformly add for 120 minutes. When the addition reaches 102 minutes, stop adding, add 0.8 parts by mass of NDM to the pre-emulsion, stir for 10 minutes, and continue to add until the addition is completed, and keep warm for 60 minutes.

[0081] 3 parts of TBHP dissolved in 15 parts of deionized water are weighed to prepare oxidant solution I; 4 parts of TBHP dissolved in 20 parts of deionized water are weighed to prepare oxidant solution II;

[0082] Weigh 1.5 parts of IAA dissolved in 15 parts of deionized water to prepare reducing agent solution I; weigh 2 parts of IAA dissolved in 20 parts of deionized water to prepare reducing agent solution II;

[0083] When the residual EA in the polymerization kettle is detected to be 380ppm, the polymerization kettle is rapidly cooled to 75°C, 3.7 parts by mass of EA are quickly added into the reactor, and stirred for 5 minutes. Oxidant solution I and reductant solution I are quickly added therein in sequence, and the interval between the addition of the two is less than 5 minutes. Keep warm for 60 minutes. Start to drop oxidant solution II and reductant solution II simultaneously, drop for 60 minutes, and keep warm for 60 minutes after the drop is completed. Cool down to less than 50°C, add 0.5 parts by mass of Tego825 defoamer and 2 parts by mass of PHCG dissolved in 7 parts of deionized water, add water to adjust the solid content to 30%, and filter the material. Emulsion 1-3 is obtained.

[0084] Example 4: Emulsion 1-4

[0085] Pre-emulsion preparation:

[0086] Add 0.8 parts of SSS and 3.5 parts of SDS to 80 parts of deionized water and stir for 30 minutes. Add 70 parts of MAA, 6 parts of AA, 116.5 parts of EA, 28 parts of EHA and 3 parts of DAP to the pre-emulsification kettle and stir thoroughly.

[0087] Weigh 0.5 parts of ammonium persulfate APS and dissolve it in 10 parts of deionized water DIW to prepare initiator solution I;

[0088] Weigh 0.9 parts of ammonium persulfate APS, 0.8 parts of SSS, and 2 parts of SDS, and dissolve them in 40 parts of deionized water DIW to prepare initiator solution II;

[0089] Add 540 parts of deionized water to the reactor, heat to 83-88°C, add 1.5 parts of SDS, 1.5 parts of anhydrous ethanol, and 0.5 parts of NaHCO3. Add initiator solution I to the reactor, and after 3 minutes, add pre-emulsion and initiator solution II, control the reaction temperature at 85-89°C, and uniformly add for 120 minutes. When the addition reaches 90 minutes, stop adding, add 0.8 parts by mass of NDM to the pre-emulsion, stir for 10 minutes, and continue to add until the addition is completed, and keep warm for 60 minutes.

[0090] 3 parts of TBHP dissolved in 15 parts of deionized water are weighed to prepare oxidant solution I; 4 parts of TBHP dissolved in 20 parts of deionized water are weighed to prepare oxidant solution II;

[0091] Weigh 1.5 parts of IAA dissolved in 15 parts of deionized water to prepare reducing agent solution I; weigh 2 parts of IAA dissolved in 20 parts of deionized water to prepare reducing agent solution II;

[0092] When the residual EA in the polymerization kettle is detected to be 480ppm, the polymerization kettle is rapidly cooled to 75°C, 3.7 parts by mass of EA are quickly added into the reactor, and stirred for 5 minutes. Oxidant solution I and reductant solution I are quickly added therein in sequence, and the interval between the addition of the two is less than 5 minutes. Keep warm for 60 minutes. Start to drop oxidant solution II and reductant solution II simultaneously, drop for 60 minutes, and keep warm for 60 minutes after the drop is completed. Cool down to less than 50°C, add 0.5 parts by mass of Tego825 defoamer and 2 parts by mass of PHCG dissolved in 7 parts of deionized water, add water to adjust the solid content to 30%, and filter the material. Emulsion 1-4 is obtained.

[0093] Example 5: Emulsion 1-5

[0094] Pre-emulsion preparation:

[0095] Add 0.8 parts of SSS and 3.5 parts of SDS to 80 parts of deionized water and stir for 30 minutes. Add 105 parts of MAA, 9 parts of AA, 175 parts of EA, 42 parts of EHA, 2.25 parts of DAP and 2.25 parts of ALMA to the pre-emulsification kettle and stir thoroughly.

[0096] Weigh 0.5 parts of ammonium persulfate APS and dissolve it in 10 parts of deionized water DIW to prepare initiator solution I;

[0097] Weigh 0.9 parts of ammonium persulfate APS, 0.8 parts of SSS, and 2 parts of SDS, and dissolve them in 40 parts of deionized water DIW to prepare initiator solution II;

[0098] Add 440 parts of deionized water to the reactor, heat to 83-88°C, add 1.5 parts of SDS, 1.5 parts of anhydrous ethanol, and 0.5 parts of NaHCO3. Add initiator solution II to the reactor, and after 3 minutes, add pre-emulsion and initiator solution II, control the reaction temperature at 85-89°C, and uniformly add for 120 minutes. When the addition reaches 114 minutes, stop adding, add 1.2 parts by mass of NDM to the pre-emulsion, stir for 10 minutes, and continue to add until the addition is completed, and keep warm for 60 minutes.

[0099] Weigh 3 parts of TBHP dissolved in 15 parts of deionized water to prepare oxidant solution I; weigh 4 parts of TBHP dissolved in 15 parts of deionized water to prepare oxidant solution II;

[0100] Weigh 1.5 parts of IAA dissolved in 15 parts of deionized water to prepare reducing agent solution I; weigh 2 parts of IAA dissolved in 15 parts of deionized water to prepare reducing agent solution II;

[0101] When the residual EA in the polymerization kettle is detected to be 690ppm, the polymerization kettle is rapidly cooled to 75℃, 3.7 parts by mass of EA are quickly added into the reactor, and stirred for 5min. Oxidant solution I and reductant solution I are quickly added therein in sequence, and the interval between the addition of the two is less than 5min. Keep warm for 60min. Start to drop oxidant solution II and reductant solution II simultaneously, drop for 60min, and keep warm for 60min after the drop is completed. Cool down to less than 50℃, add 0.1 parts by mass of Tego825 defoamer and 2 parts by mass of PHCG dissolved in 7 parts of deionized water, add water to adjust the solid content to 35%, and filter the material. Emulsion 1-5 is obtained.

[0102] Example 6: Emulsion 1-6

[0103] Pre-emulsion preparation:

[0104] Add 0.8 parts of SSS and 3.5 parts of SDS to 80 parts of deionized water and stir for 30 minutes. Add 70 parts of MAA, 6 parts of AA, 119 parts of EA, 28 parts of EHA and 3 parts of DAP to the pre-emulsification kettle and stir thoroughly.

[0105] Weigh 0.5 parts of ammonium persulfate APS and dissolve it in 10 parts of deionized water DIW to prepare initiator solution I;

[0106] Weigh 0.9 parts of ammonium persulfate APS, 0.8 parts of SSS, and 2 parts of SDS, and dissolve them in 40 parts of deionized water DIW to prepare initiator solution II;

[0107] Add 540 parts of deionized water to the reactor, heat to 83-88°C, add 1.5 parts of SDS, 1.5 parts of anhydrous ethanol, and 0.5 parts of NaHCO3. Add initiator solution II to the reactor, and after 3 minutes, add pre-emulsion and initiator solution II, control the reaction temperature at 85-89°C, and uniformly add for 120 minutes. When the addition reaches 102 minutes, stop adding, add 0.8 parts by mass of NDM to the pre-emulsion, stir for 10 minutes, and continue to add until the addition is completed, and keep warm for 60 minutes.

[0108] 3 parts of TBHP dissolved in 15 parts of deionized water are weighed to prepare oxidant solution I; 4 parts of TBHP dissolved in 20 parts of deionized water are weighed to prepare oxidant solution II;

[0109] Weigh 1.5 parts of IAA dissolved in 15 parts of deionized water to prepare reducing agent solution I; weigh 2 parts of IAA dissolved in 20 parts of deionized water to prepare reducing agent solution II;

[0110] When the residual EA in the polymerization kettle is detected to be 800ppm, the polymerization kettle is rapidly cooled to 75°C, 1.2 parts by mass of EA is quickly added into the reactor, and stirred for 5 minutes. Oxidant solution I and reductant solution I are quickly added therein in sequence, and the interval between the addition of the two is less than 5 minutes. Keep warm for 60 minutes. Start to drop oxidant solution II and reductant solution II simultaneously, drop for 60 minutes, and keep warm for 60 minutes after the drop is completed. Cool down to less than 50°C, add 0.5 parts by mass of Tego825 defoamer and 2 parts by mass of PHCG dissolved in 7 parts of deionized water, add water to adjust the solid content to 30%, and filter the material. Emulsion 1-6 is obtained.

[0111] Example 7: Emulsion 1-7

[0112] Pre-emulsion preparation:

[0113] Add 0.8 parts of SSS and 3.5 parts of SDS to 80 parts of deionized water and stir for 30 minutes. Add 70 parts of MAA, 6 parts of AA, 105.6 parts of EA, 28 parts of EHA and 3 parts of DAP to the pre-emulsification kettle and stir thoroughly.

[0114] Weigh 0.5 parts of ammonium persulfate APS and dissolve it in 10 parts of deionized water DIW to prepare initiator solution I;

[0115] Weigh 0.9 parts of ammonium persulfate APS, 0.8 parts of SSS, and 2 parts of SDS, and dissolve them in 40 parts of deionized water DIW to prepare initiator solution II;

[0116] Add 540 parts of deionized water to the reactor, heat to 83-88°C, add 1.5 parts of SDS, 1.5 parts of anhydrous ethanol, and 0.5 parts of NaHCO3. Add initiator solution II to the reactor, and after 3 minutes, add pre-emulsion and initiator solution II, control the reaction temperature at 85-89°C, and uniformly add for 120 minutes. When the addition reaches 102 minutes, stop adding, add 0.8 parts by mass of NDM to the pre-emulsion, stir for 10 minutes, and continue to add until the addition is completed, and keep warm for 60 minutes.

[0117] 3 parts of TBHP dissolved in 15 parts of deionized water are weighed to prepare oxidant solution I; 4 parts of TBHP dissolved in 20 parts of deionized water are weighed to prepare oxidant solution II;

[0118] Weigh 1.5 parts of IAA dissolved in 15 parts of deionized water to prepare reducing agent solution I; weigh 2 parts of IAA dissolved in 20 parts of deionized water to prepare reducing agent solution II;

[0119] When the residual EA in the polymerization kettle is detected to be 980ppm, the polymerization kettle is rapidly cooled to 75°C, 14.6 parts by mass of EA is quickly added into the reactor, and stirred for 5 minutes. Oxidant solution I and reductant solution I are quickly added therein in sequence, and the interval between the addition of the two is less than 5 minutes. Keep warm for 60 minutes. Start to drop oxidant solution II and reductant solution II simultaneously, drop for 60 minutes, and keep warm for 60 minutes after the drop is completed. Cool down to less than 50°C, add 0.5 parts by mass of Tego825 defoamer and 2 parts by mass of PHCG dissolved in 7 parts of deionized water, add water to adjust the solid content to 30%, and filter the material. Emulsion 1-7 is obtained.

[0120] Comparative Example 1: Emulsion 2-1

[0121] Pre-emulsion preparation:

[0122] Add 0.8 parts of SSS and 3.5 parts of SDS to 80 parts of deionized water and stir for 30 minutes. Add 70 parts of MAA, 6 parts of AA, 120.2 parts of EA, 28 parts of EHA and 3 parts of DAP to the pre-emulsification kettle and stir thoroughly.

[0123] Weigh 0.5 parts of ammonium persulfate APS and dissolve it in 10 parts of deionized water DIW to prepare initiator solution I;

[0124] Weigh 0.9 parts of ammonium persulfate APS, 0.8 parts of SSS, and 2 parts of SDS, and dissolve them in 40 parts of deionized water DIW to prepare initiator solution II;

[0125] Add 540 parts of deionized water to the reactor, heat to 83-88°C, add 1.5 parts of SDS, 1.5 parts of anhydrous ethanol, and 0.5 parts of NaHCO3. Add initiator solution I to the reactor, and after 3 minutes, add pre-emulsion and initiator solution II, control the reaction temperature at 85-89°C, and uniformly add for 120 minutes. When the addition reaches 102 minutes, stop adding, add 0.8 parts by mass of NDM to the pre-emulsion, stir for 10 minutes, and continue to add until the addition is completed, and keep warm for 60 minutes.

[0126] 3 parts of TBHP dissolved in 15 parts of deionized water are weighed to prepare oxidant solution I; 4 parts of TBHP dissolved in 20 parts of deionized water are weighed to prepare oxidant solution II;

[0127] Weigh 1.5 parts of IAA dissolved in 15 parts of deionized water to prepare reducing agent solution I; weigh 2 parts of IAA dissolved in 20 parts of deionized water to prepare reducing agent solution II;

[0128] When the residual EA in the polymerization kettle is detected to be 100ppm, the polymerization kettle is rapidly cooled to 75℃, 3.7 parts by mass of EA are quickly added into the reactor, and stirred for 5 minutes. Oxidant solution I and reductant solution I are quickly added therein in sequence, and the interval between the addition of the two is less than 5 minutes. Keep warm for 60 minutes. Start to drop oxidant solution II and reductant solution II simultaneously, drop for 60 minutes, and keep warm for 60 minutes after the drop is completed. Cool down to less than 50℃, add 0.5 parts by mass of Tego825 defoamer and 2 parts by mass of PHCG dissolved in 7 parts of deionized water, add water to adjust the solid content to 30%, and filter the material. Emulsion 2-1 is obtained.

[0129] Comparative Example 2: Emulsion 2-2

[0130] Pre-emulsion preparation:

[0131] Add 0.8 parts of SSS and 3.5 parts of SDS to 80 parts of deionized water and stir for 30 minutes. Add 70 parts of MAA, 6 parts of AA, 116.5 parts of EA, 28 parts of EHA and 3 parts of DAP to the pre-emulsification kettle and stir thoroughly.

[0132] Weigh 0.5 parts of ammonium persulfate APS and dissolve it in 10 parts of deionized water DIW to prepare initiator solution I;

[0133] Weigh 0.9 parts of ammonium persulfate APS, 0.8 parts of SSS, and 2 parts of SDS, and dissolve them in 40 parts of deionized water DIW to prepare an initiator solution I;

[0134] Add 540 parts of deionized water to the reactor, heat to 83-88°C, add 1.5 parts of SDS, 1.5 parts of anhydrous ethanol, and 0.5 parts of NaHCO3. Add initiator solution I to the reactor, and after 3 minutes, add pre-emulsion and initiator solution II, control the reaction temperature at 85-89°C, and uniformly add for 120 minutes. When the addition reaches 102 minutes, stop adding, add 0.8 parts by mass of NDM to the pre-emulsion, stir for 10 minutes, and continue to add until the addition is completed, and keep warm for 60 minutes.

[0135] 3 parts of TBHP dissolved in 15 parts of deionized water are weighed to prepare oxidant solution I; 4 parts of TBHP dissolved in 20 parts of deionized water are weighed to prepare oxidant solution II;

[0136] Weigh 1.5 parts of IAA dissolved in 15 parts of deionized water to prepare reducing agent solution I; weigh 2 parts of IAA dissolved in 20 parts of deionized water to prepare reducing agent solution II;

[0137] When the residual EA in the polymerization kettle is detected to be 1200ppm, the polymerization kettle is rapidly cooled to 75°C, 3.7 parts by mass of EA are quickly added into the reactor, and stirred for 5 minutes. Oxidant solution I and reductant solution I are quickly added therein in sequence, and the addition interval between the two is less than 5 minutes. Keep warm for 60 minutes. Start to drop oxidant solution II and reductant solution II simultaneously, drop for 60 minutes, and keep warm for 60 minutes after the drop is completed. Cool down to less than 50°C, add 0.5 parts by mass of Tego825 defoamer and 2 parts by mass of PHCG dissolved in 7 parts of deionized water, add water to adjust the solid content to 30%, and filter the material. Emulsion 2-2 is obtained.

[0138] In a specific embodiment, the acrylate suspension thickener is used to prepare a shampoo formula that includes the following components in parts by weight:

[0139] Water 66-77.7 parts, thickener 7.0-9.0 parts, surfactant 15-20 parts, cationic compound 0-1.0 parts, flavor 0-1.0 parts, pigment 0-1.0 parts, pearlescent 0-1.0 parts, neutralizer 0.3-1.0 parts. According to different application products and performance requirements, those skilled in the art can appropriately adjust the other ingredients and contents except the thickener.

[0140] In a specific embodiment of the present application, the acrylic ester suspension thickener is used to prepare a shampoo formula comprising:

[0141] 71 parts by mass of water, 8.2 parts by mass of thickener sodium alginate, 18 parts by mass of surfactant chloride-2-hydroxy-3-(trimethylamino)propyl polyoxyethylene cellulose ether, 0.5 parts by mass of cationic compound ammonium lauryl sulfate, 0.5 parts by mass of flavor, 0.6 parts by mass of pigment, 0.4 parts by mass of ethylene glycol stearate, and 0.8 parts by mass of neutralizer sodium hydroxide.

[0142] (1) The suspension thickening performance of acrylic emulsion in shampoo formula is mainly characterized by the viscosity and yield value of the shampoo formula. The test methods are:

[0143] ①Use Brookfeald viscometer, 64# rotor to measure the viscosity at 20r;

[0144] ② The yield value is represented by subtracting the viscosity value measured at 1r from the viscosity value measured at 0.5r and then dividing by 100. The larger the yield value, the better the suspension.

[0145] (2) The transparency of acrylic emulsion in shampoo formula is mainly characterized by ultraviolet spectrophotometer. The test methods are as follows: using ultraviolet spectrophotometer, at a wavelength of 420nm, the transmittance of the sample is tested after zero calibration with pure water as the reference. The higher the transmittance, the better the transparency of the shampoo formula.

[0146] Table 3 Experimental conditions of the embodiments and comparative examples

[0147]

[0148] Table 4 Emulsion performance test comparison

[0149]

[0150] Among them, the sample of Example 1-1 has good performance repeatability during the industrialization process, while the performance of Comparative Example 2-1 fluctuates during the industrialization process. The present invention has good suspension properties while ensuring high transparency through a special production process combined with an ingenious overall formula design, and the prepared emulsion Example 1-1 solves the problem of fluctuations in industrial production.

[0151] By comparing the examples with the comparative examples, it can be found that the insertion timing of the soft monomer has a significant effect on the suspension and transparency of the product. When the residual soft monomer content is between 200ppm and 1000ppm, the emulsion production stability and performance are good.

[0152] Finally, it should be noted that the above aqueous acrylic suspension thickener embodiments are only used to describe the preferred embodiments of the present invention, rather than to limit the protection scope of the present invention. Although the present invention is described in detail with reference to the preferred embodiments, those skilled in the art should understand that various modifications and improvements made by modifying or equivalently replacing the technical solution of the present invention should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing an aqueous acrylic acid suspension thickening emulsion, characterized in that: The steps include: (1) Add water to the reaction kettle, heat it to 70-95°C, and add emulsifier I and additives to the bottom of the kettle; (2) At 70-95° C., initiator I is added to the reactor. After 5-10 minutes, pre-emulsion, initiator II, and emulsifier II are simultaneously added to the reactor. When the amount of pre-emulsion added is 75%-95% of its mass, chain transfer agent is added to the pre-emulsion. After stirring for 5-15 minutes, the pre-emulsion is continued to be added until all the pre-emulsion is added. The total addition time is 120-240 minutes. (3) Keep warm for 30-90 minutes, cool to 65-80°C, detect the residual monomer of soft monomer during the keeping warm process, add soft monomer to the reactor when the residual monomer of soft monomer is 200-1000ppm, stir for 5-20 minutes, add oxidant I and reductant I, and the interval between adding oxidant I and reductant I is less than 5 minutes. Keep warm for 30-60 minutes, then start adding oxidant II and reductant II, which takes 60-120 minutes. After the addition is completed, keep warm for 60-120 minutes.

2. The preparation method according to claim 1, characterized in that: After the insulation is completed, the temperature is lowered to 50-60°C, the kettle is turned, a defoamer and a preservative are added, and the material is filtered out.

3. The preparation method according to claim 1 or 2, characterized in that: In the preparation method, the amount of each component added is: Pre-emulsion 220-630 parts by mass, preferably 270-490 parts by mass, Emulsifier 2-10 parts by mass, preferably 3-9 parts by mass, 0.3-3 parts by mass of auxiliary agent, preferably 0.5-2 parts by mass, Chain transfer agent 0.1-3 parts by mass, preferably 0.2-1.5 parts by mass, Initiator 0.1-2 parts by mass, preferably 0.1-1.5 parts by mass, Oxidant 0.5-6 parts by mass, preferably 0.8-4 parts by mass, 0.4-2 parts by mass of reducing agent, preferably 0.5-1.5 parts by mass, Defoaming agent 0-1 mass part, preferably 0.2-0.8 mass part, 0-4 parts by mass, preferably 1.5-3.5 parts by mass, of preservatives; 340-775 parts by mass of water, preferably 450-750 parts by mass; The total mass of the above components is 1000 parts.

4. The preparation method according to claim 3, characterized in that: The amount of emulsifier added refers to the total amount of emulsifier I and emulsifier II; preferably, the mass ratio of emulsifier I to emulsifier II is 1:20-20:1; The amount of initiator added refers to the total amount of initiator I and initiator II; preferably, the mass ratio of initiator I to initiator II is 1:20-20:1; The amount of oxidant added refers to the total amount of oxidant I and oxidant II; preferably, the mass ratio of oxidant I to oxidant II is 1:20-20:1; The amount of reducing agent added refers to the total amount of reducing agent I and reducing agent II; preferably, the mass ratio of reducing agent I to reducing agent II is 1:20-20:

1.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The emulsifier I and emulsifier II are independently selected from one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, alkyl polyoxyethylene ether, sodium p-styrene sulfonate, fatty alcohol polyoxyethylene ether and salts thereof, and fatty alcohol ether phosphate and salts thereof, preferably sodium dodecyl sulfate and sodium p-styrene sulfonate; Preferably, in step (1), the auxiliary agent is one or more of alkali metal carbonates, alkali metal bicarbonates, and alcohols, preferably one or more of sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, methanol, and ethanol; Preferably, in step (2), the initiator is a peroxide, preferably one or more of ammonium persulfate, sodium persulfate, potassium persulfate, cumene hydroperoxide, and tert-butyl hydroperoxide.

6. The preparation method according to any one of claims 1 to 5, characterized in that: In the step (2), the pre-emulsion comprises the following components, calculated based on 100 parts by mass of the total mass of the pre-emulsion: 18-40 parts by mass of hard monomer, preferably 20-35 parts by mass; Soft monomer 45-65 parts by mass, preferably 45-58 parts by mass; Functional monomer 0-3 parts by mass, preferably 0-1.5 parts by mass; Emulsifier III 0-1.2 parts by mass, preferably 0-1 parts by mass; Water: 10-30 parts by mass, preferably 13-27 parts by mass.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The method for preparing the pre-emulsion comprises the following steps: adding water and an emulsifier into a pre-emulsification kettle 1, stirring evenly, and then adding a soft monomer, optionally a functional monomer, and a hard monomer, and stirring.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The emulsifier III in the pre-emulsion is one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, alkyl polyoxyethylene ether, sodium p-styrene sulfonate, fatty alcohol polyoxyethylene ether and its salts, and fatty alcohol ether phosphate and its salts; Preferably, the hard monomer in the pre-emulsion comprises one or more of styrene, methacrylic acid, acrylic acid, and methyl methacrylate, preferably methacrylic acid and methyl methacrylate; Preferably, the soft monomer in the pre-emulsion comprises one or more of isooctyl acrylate, butyl acrylate, ethyl acrylate, isooctyl methacrylate, 2-ethylhexyl acrylate, and lauryl methacrylate; Preferably, the functional monomer in the pre-emulsion comprises one or more of hydroxyethyl acrylate, β-acryloxypropionic acid, diallyl phthalate, allyl methacrylate, ethylene glycol dimethacrylate, and 1,3-butanediol dimethacrylate.

9. The preparation method according to any one of claims 1 to 8, characterized in that: In the step (2), the chain transfer agent is one or more of n-dodecyl mercaptan, butyl mercapto, mercaptopropionic acid, and mercaptoethanol; Preferably, in step (3), the amount of the soft monomer added is 0.5%-10% by weight of the total monomers, preferably 0.5%-5%; Preferably, in step (3), the soft monomer is added all at once or quickly within 5 minutes; Preferably, in step (3), the oxidant I is added at one time or quickly added within 5 minutes, and the reducing agent solution I is added at one time or quickly added within 5 minutes; Preferably, in step (3), the initiator I and the initiator II are independently selected from peroxides, preferably one or more selected from sodium persulfate, ammonium persulfate, tert-butyl hydroperoxide, cumene hydroperoxide, and hydrogen peroxide, preferably tert-butyl hydroperoxide; Preferably, in step (3), the reducing agent I and the reducing agent II are independently selected from one or more of sodium metabisulfite, disodium metabisulfite, ascorbic acid, and bleaching powder, preferably ascorbic acid; Preferably, in step (3), the defoaming agent is one or more of an organosilicon defoaming agent, a mineral oil defoaming agent, and a polyether defoaming agent, preferably an organosilicon defoaming agent; Preferably, in step (3), the preservative is one or more of triazine preservatives, bisoxazolinidine preservatives, isothiazolinone preservatives, and broad-spectrum preservatives, preferably a broad-spectrum preservative.

10. The preparation method according to any one of claims 1 to 9, characterized in that: The solid content of the aqueous acrylic acid suspension thickening emulsion is 25%-40%, and the average particle size is 90-150nm.

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