Reactive emulsifier and application thereof in acrylic emulsion polymerization

Abstract

The invention discloses a reactive emulsifier and application thereof in acrylic emulsion polymerization, and belongs to the technical field of emulsifiers. The reactive emulsifier is prepared from the following optional raw materials: a sealing agent, a hydroxyl compound or diamine, wherein the raw materials comprise hydrophilic diisocyanate containing a sulfonate group and hydroxyl acrylate; wherein the sealing agent is a hydrogen-containing compound; the hydroxyl compound comprises dihydric alcohol, alkoxy alcohol or hydroxyl-terminated siloxane. The invention provides a reactive emulsifier for acrylic emulsion polymerization, which not only has very high emulsification efficiency and keeps the stability of an emulsification system, but also can participate in copolymerization of a free radical system and become a part of an acrylic resin structure. The adsorption type emulsifier is prevented from being desorbed from polymer particles or migrated in a latex film, and the molecular concentration of the emulsifier on the surfaces of the emulsion particles is reduced, so that the stability of the emulsion can be improved, and the water resistance, strength, light, heat and other properties of the latex film are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of emulsifiers, and particularly to a reactive emulsifier and its application in acrylic emulsion polymerization. Background Art

[0002] At present, waterborne acrylic emulsions have been applied to some extent in the fields of waterborne acrylic adhesives, waterborne acrylic baking paints, waterborne acrylic composite adhesives, etc. However, due to problems such as the decline in the water resistance of waterborne products, poor surface quality, the presence of bubbles, and the decline in strength performance, the popularization and application of acrylic emulsions have been affected. The reason is closely related to the use of traditional non-ionic emulsifiers such as fatty alcohol polyoxyethylene ethers, anionic-non-ionic emulsifiers such as polyoxyethylene ether sulfates, and anionic emulsifiers such as sodium alkyl sulfates in the preparation of waterborne acrylic emulsions in the prior art. These emulsifiers remain in the product in an adsorbed form and are prone to migrate to the surface, forming a layer of non-covalently bonded emulsifier layer on the film surface. Once exposed to water or moisture, it will cause the glue film to absorb water and swell, resulting in defects such as "blooming", "whitening", and a decrease in gloss, causing the surface of the product to be uneven and the adhesion to decrease, seriously affecting the water resistance and chemical corrosion resistance of the glue film, and the glue film is prone to pinholes, resulting in a decrease in the mechanical and optical properties of the polymer.

[0003] Emulsifiers play an important role in emulsion polymerization. They not only affect the polymerization rate, degree of polymerization, number and diameter of latex particles, but also have a significant impact on the stability, film-forming property, and product performance of the emulsion. Therefore, new progress has been made in the development of reactive emulsifiers to improve acrylic emulsion polymerization and performance in recent years. For example, a reactive polyurethane anionic-non-ionic emulsifier disclosed in CN115926105A and a reactive polyurethane anionic emulsifier disclosed in CN115926106A can rapidly disperse and emulsify solvent-based resins into waterborne resins, greatly simplifying the preparation process of waterborne resins and reducing the manufacturing cost of waterborne resins. However, both of these emulsifiers are only applicable to the waterborne conversion of two-component solvent-based resins and are not applicable to the waterborne conversion of one-component solvent-based resins because the reactive functional groups carried by these two emulsifiers must react with the curing agent before they will not remain free in the product. In the prior art, there is still a problem of emulsifier residue after the film formation of acrylic emulsions. Summary of the Invention

[0004] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art. To this end, one of the objectives of the present invention is to provide a reactive emulsifier for acrylic emulsion polymerization, which can completely replace the application of adsorption-type emulsifiers in acrylic emulsion polymerization. Another objective of the present invention is to provide a preparation method of this reactive emulsifier. A third objective of the present invention is to provide the application of this reactive emulsifier in acrylic emulsion polymerization. A fourth objective of the present invention is to provide an acrylic emulsion prepared from the above reactive emulsifier as a raw material. A fifth objective of the present invention is to provide the application of the above-prepared acrylic emulsion in the preparation of waterborne acrylic products.

[0005] In order to achieve the above objectives, the technical solutions adopted by the present invention are as follows:

[0006] In the first aspect of the present invention, a reactive emulsifier is provided. The reactive emulsifier is prepared from raw materials including a hydrophilic diisocyanate containing a sulfonate group and a hydroxyacrylate, and the following optional raw materials: a blocking agent, a hydroxy compound or a diamine; the blocking agent is a hydrogen-containing compound; the hydroxy compound includes a diol, an alkoxy alcohol or a terminal hydroxy siloxane;

[0007] The structural general formula of the reactive emulsifier is shown in formula (Ⅰ):

[0008]

[0009] In formula (Ⅰ), M is an alkali metal ion or an ammonium ion, and m is 1-6;

[0010] R1 is or -O-R5, or -O-R6-OH, or -O-R6-H, or an amino group;

[0011] R2 is H or -CH3;

[0012] R3 is an alkylene chain containing a urethane group;

[0013] R4 is a hydrocarbon group of C n H 2n with n being 2 or 3;

[0014] R5 is a group of the blocking agent other than the active hydrogen;

[0015] R6 is a hydrocarbon group, or an alkoxy group, or a siloxane group.

[0016] The reactive emulsifier provided by the present invention has a molecular structure containing a urethane group and at least one hydrophilic sulfonate group, and at least one end is provided with a double bond. 1. Since the reactive emulsifier structure has at least one double bond, as an emulsifier for acrylic emulsion polymerization, it can carry out free radical copolymerization with the double bond monomer and become a part of the acrylic resin structure. Therefore, whether the prepared acrylic emulsion is applied in a single-component form or in a two-component form (matched with a curing agent), there is no free emulsifier single molecule present. So, the acrylic emulsion prepared with the reactive emulsifier of the present invention has no influence on the performance of the final product, and even can improve the surface performance, water resistance, adhesion, etc. of the product. 2. Since the reactive emulsifier structure contains a sulfonate group with very good hydrophilicity, only a small amount of addition is required to have good emulsifying performance. After free radical polymerization occurs, the emulsifier molecule copolymerizes with the acrylic monomer, and the sulfonate group enters the acrylic copolymer structure, which can continuously and effectively reduce the surface tension, maintain the stability of emulsion polymerization, and the latex particle size is relatively small with good mechanical stability. 3. Since the reactive emulsifier structure contains a urethane group, as an emulsifier for acrylic emulsion polymerization, it copolymerizes with the double bond monomer, introducing the polyurethane structure into the acrylic structure, playing a modification role, and can improve the impact strength and other properties of acrylic products.

[0017] According to some embodiments of the present invention, the raw materials for preparing the reactive emulsifier can be selected from any one of the following:

[0018] A hydrophilic diisocyanate containing a sulfonate group and a hydroxyacrylate;

[0019] A hydrophilic diisocyanate containing a sulfonate group, a hydroxyacrylate and a blocking agent;

[0020] A hydrophilic diisocyanate containing a sulfonate group, a hydroxyacrylate and a hydroxy compound;

[0021] A hydrophilic diisocyanate containing a sulfonate group, a hydroxyacrylate and a diamine.

[0022] According to some embodiments of the present invention, the raw materials for preparing the hydrophilic diisocyanate containing a sulfonate group include a diisocyanate and a hydrophilic chain extender containing a sulfonate group; the molar ratio of the diisocyanate to the hydrophilic chain extender containing a sulfonate group is (2 - 6):1.

[0023] According to some embodiments of the present invention, the reaction formula for preparing the hydrophilic diisocyanate containing a sulfonate group is shown in the following formula (1):

[0024]

[0025] OCN-R7-NCO represents a diisocyanate, and R7 represents the group of the diisocyanate other than the two -NCO groups, such as the hydrocarbon group of TDI, HDI or IPDI; represents a hydrophilic chain extender containing a sulfonate group, R8 represents a hydrocarbon group, M is an alkali metal ion or an ammonium ion, and m is 1 - 6.

[0026] According to some specific embodiments of the present invention, the diisocyanate is a hydrophilic diisocyanate, such as at least one selected from aqueous TDI (toluene diisocyanate), aqueous MDI (diphenylmethane diisocyanate), aqueous IPDI (isophorone diisocyanate), aqueous HDI (hexamethylene diisocyanate), and aqueous HMDI (4,4'-dicyclohexylmethane diisocyanate).

[0027] According to some specific embodiments of the present invention, the hydrophilic chain extender containing a sulfonate group is at least one small molecule diol containing a sulfonate group or a small molecule diol containing an amino sulfonate group; the small molecule diol containing a sulfonate group is at least one of sodium 1,2-dihydroxy-3-propane sulfonate, sodium 1,4-dihydroxybutane-2-sulfonate or a small molecule sulfonate diol; the small molecule sulfonate diol is prepared by an esterification reaction of a dicarboxylate sulfonate with a small molecule diol and a small molecule dicarboxylic acid; the dicarboxylate sulfonate is at least one of sodium dicarboxylate sulfonate, potassium dicarboxylate sulfonate or ammonium dicarboxylate sulfonate; the molecular weight of the small molecule sulfonate diol is 350 - 3000, the small molecule diol is a diol with a molecular weight less than 300, and the small molecule dicarboxylic acid is a dicarboxylic acid with a molecular weight less than 300.

[0028] For the specific preparation method of the hydrophilic diisocyanate containing a sulfonate group of the present invention, reference can be made to the description in CN111423343A.

[0029] According to some embodiments of the present invention, the hydroxyacrylate includes at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

[0030] According to some embodiments of the present invention, the blocking agent includes at least one of methanol, ethanol, isopropyl alcohol, methyl ethyl ketone oxime, acetone oxime, methyl isobutyl oxime, caprolactam, phenol, and catechol.

[0031] According to some specific embodiments of the present invention, the blocking agent includes at least one of methanol, ethanol, methyl ethyl ketone oxime, caprolactam, and phenol.

[0032] According to some embodiments of the present invention, the diamine includes at least one of ethylenediamine, propylenediamine, cyclohexanediamine, diethyltoluenediamine, sodium ethylenediamine ethanesulfonate, and sodium 2,4-diaminobenzenesulfonate.

[0033] In some specific embodiments of the present invention, the sodium 2-(2-aminoethylamino)ethanesulfonate or sodium 2,4-diaminobenzenesulfonate can respectively select aqueous solution products with a solid content of 40% to 60%.

[0034] According to some embodiments of the hydroxy compound of the present invention, the diol includes at least one of 3-methyl-1,5-pentanediol, neopentyl glycol, ethylene glycol, cyclohexanediol, methylpropanediol, 1,3-propanediol, 1,4-bis(hydroxymethyl)cyclohexane, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,2-propanediol, diethylene glycol, tetrahydrofuran diol, 1,6-hexanediol, trimethylpentanediol, butylethylpropanediol, dipropylene glycol, tripropylene glycol, ethylhexanediol.

[0035] According to some embodiments of the hydroxy compound of the present invention, the alkoxy alcohol includes at least one of polyethylene glycol and fatty alcohol polyoxyethylene ether.

[0036] According to some embodiments of the hydroxy compound of the present invention, the hydroxy-terminated siloxane includes at least one of hydroxy silicone oil and hydroxy-terminated silicone resin. In some embodiments, the hydroxy-terminated siloxane can select a dihydroxy silicone oil with an average molecular weight of 300 to 3000.

[0037] According to some embodiments of the present invention, the reactive emulsifier includes four structural forms: A, B, C, and D.

[0038] Both ends of the reactive emulsifier A have double bonds; that is, in formula (I), M is an alkali metal ion or an ammonium ion, m is 1 - 6; R1 is R2 is H or -CH3; R3 is an alkylene chain containing a carbamate group; R4 is C n H 2n hydrocarbon group, and n is 2 or 3.

[0039] One end of the reactive emulsifier B has a double bond and the other end is blocked by a blocking agent; that is, in formula (I), M is an alkali metal ion or an ammonium ion, m is 1 - 6; R1 is -O-R5; R2 is H or -CH3; R3 is an alkylene chain containing a carbamate group; R4 is C n H 2n hydrocarbon group, n is 2 or 3; R5 is a group other than active hydrogen of the blocking agent.

[0040] One end of the reactive emulsifier C has a double bond and the other end is a hydroxyl group or hydrogen; that is, in formula (I), M is an alkali metal ion or an ammonium ion, m is 1 - 6; R1 is -O-R6-OH or -O-R6-H; R2 is H or -CH3; R3 is an alkylene chain containing a carbamate group; R4 is C n H 2nThe alkyl group, n is 2 or 3; R6 is an alkyl group, an alkoxy group, or a siloxanyl group.

[0041] One end of the reactive emulsifier D has a double bond and the other end is an amino group; that is, in formula (I), M is an alkali metal ion or an ammonium ion, m is 1-6; R1 is an amino group; R2 is H or -CH3; R3 is an alkylene chain containing a urethane group; R4 is C n H 2n The alkyl group, n is 2 or 3. Among them, the amino group of R1 refers to the group of the diamine except for one hydrogen.

[0042] According to the reactive emulsifier A provided by the present invention, the double bonds at both ends of the emulsifier can participate in the free radical polymerization reaction and generate branches, improving the performance of the product.

[0043] According to the reactive emulsifier B provided by the present invention, the double bond at one end of the emulsifier can participate in the free radical polymerization reaction, and the blocked other end can release -NCO groups during the high-temperature curing of the acrylic emulsion and undergo a curing reaction with hydroxyl groups, mainly used for preparing single- and two-component waterborne acrylic high-temperature baking paints.

[0044] According to the reactive emulsifier C provided by the present invention, one end double bond of the emulsifier can participate in the free radical polymerization reaction, and the other end hydroxyl group can participate in the post-curing reaction together with the hydroxyl group of the acrylic resin; when R6 contains a polyoxyethylene chain link, the reactive emulsifier has an anionic-nonionic emulsifying function; when R6 contains a siloxanyl chain link, the reactive emulsifier can improve the scratch resistance, stain resistance and other properties of the acrylic resin.

[0045] According to the reactive emulsifier D provided by the present invention, one end double bond of the emulsifier can participate in the free radical polymerization reaction, and the other end amino group can neutralize the carboxyl group in the acrylic emulsion to form an ammonium salt with good hydrophilicity, further improving the hydrophilicity and stability of the emulsion and facilitating the reduction of the amount of emulsifier used.

[0046] According to some embodiments of the present invention, in formula (I), M is a K ion or a Na ion.

[0047] According to some embodiments of the present invention, in formula (I), m is 1 or 2.

[0048] According to some embodiments of the present invention, in formula (I), R3 is a C1-C20 alkylene chain containing a urethane group.

[0049] According to some embodiments of the present invention, in formula (I), R4 is

[0050] According to some embodiments of the present invention, in formula (I), R5 is methyl, ethyl or isopropyl.

[0051] According to some embodiments of the present invention, in the formula (I), the alkoxy group of R6 may be selected from polyoxyethylene groups.

[0052] According to some embodiments of the present invention, in the formula (I), the siloxanyl group of R6 may be selected from dimethylsiloxy groups, such as where n is a positive integer, and may be selected from 3 to 13, for example.

[0053] The second aspect of the present invention provides a method for preparing the reactive emulsifier described in the first aspect of the present invention, including the following steps:

[0054] React a hydrophilic diisocyanate containing a sulfonate group and a hydroxyacrylate, or react a hydrophilic diisocyanate containing a sulfonate group, a hydroxyacrylate, and any one of a blocking agent, a hydroxy compound, and a diamine to obtain the reactive emulsifier.

[0055] According to some embodiments of the present invention, when the raw materials are only a hydrophilic diisocyanate containing a sulfonate group and a hydroxyacrylate, the molar ratio of the hydrophilic diisocyanate containing a sulfonate group to the hydroxyacrylate is 1:(2 - 2.5).

[0056] According to some embodiments of the present invention, when the raw materials include a hydrophilic diisocyanate containing a sulfonate group, a hydroxyacrylate, and any one of a blocking agent, a hydroxy compound, and a diamine, the molar ratio of the hydrophilic diisocyanate containing a sulfonate group, the hydroxyacrylate, the blocking agent or the hydroxy compound or the diamine is 1:(1 - 1.5):(1 - 1.5).

[0057] According to some embodiments of the present invention, react a hydrophilic diisocyanate containing a sulfonate group and a hydroxyacrylate to obtain a reactive emulsifier A.

[0058] According to some specific embodiments of the present invention, the reaction formula for preparing the reactive emulsifier A is shown in the following formula (2):

[0059]

[0060] represents a hydrophilic diisocyanate containing a sulfonate group, R3 is an alkylene chain containing a urethane group, and may be selected from C1 - C20 alkylene chains containing a urethane group; m is 1 - 6 and may be selected from any positive integer in 1 - 6; HO-R9=CH2 represents a hydroxyacrylate, and R9 represents a hydrocarbon group.

[0061] According to some embodiments of the present invention, react a hydrophilic diisocyanate containing a sulfonate group, a hydroxyacrylate, and a blocking agent containing active hydrogen to obtain a reactive emulsifier B.

[0062] According to some specific embodiments of the present invention, the reaction formula for preparing the reactive emulsifier B is shown in the following formula (3):

[0063] represents a hydrophilic diisocyanate containing a sulfonate group, and the definitions of R3 and m are the same as above; HO-R9═CH2 represents a hydroxyacrylate, and R9 represents a hydrocarbon group; R 10 -OH represents a blocking agent, and R 10 represents a group of the blocking agent other than the hydroxyl group.

[0064] According to some embodiments of the present invention, a hydrophilic diisocyanate containing a sulfonate group, a hydroxyacrylate, and a hydroxy compound are reacted to obtain a reactive emulsifier C.

[0065] According to some specific embodiments of the present invention, the reaction formula for preparing the reactive emulsifier C is shown in the following formula (4):

[0066] represents a hydrophilic diisocyanate containing a sulfonate group, and the definitions of R3 and m are the same as above; HO-R9═CH2 represents a hydroxyacrylate, and R9 represents a hydrocarbon group; HO-R 11 -OH represents a diol, and R 11 represents a hydrocarbon group.

[0067] According to some embodiments of the present invention, a hydrophilic diisocyanate containing a sulfonate group, a hydroxyacrylate, and a diamine are reacted to obtain a reactive emulsifier D.

[0068] According to some specific embodiments of the present invention, the reaction formula for preparing the reactive emulsifier D is shown in the following formula (5):

[0069] represents a hydrophilic diisocyanate containing a sulfonate group, and the definitions of R3 and m are the same as above; HO-R9═CH2 represents a hydroxyacrylate, and R9 represents a hydrocarbon group; NH2-R 12 -NH2 represents a diamine, and R 12 represents a group of the diamine other than the two -NH2 groups.

[0070] According to some embodiments of the present invention, the hydrocarbon groups in R6, R7, R8, and R9 can each be selected from hydrocarbon groups having 1 to 20 carbon atoms, or more specifically, alkyl groups having 1 to 15 carbon atoms, etc. Here, 1 to 20 or 1 to 15 refers to any positive integer that can be selected from 1 to 20 or 15, or the range between any two positive integers in these intervals, such as C2 - C12 and C3 - C10.

[0071] According to some embodiments of the present invention, the reaction for preparing the reactive emulsifier is carried out in an organic solvent. Optional organic solvents include esters, ethers, or ketones, such as at least one of propylene glycol methyl ether acetate, ethyl acetate, and acetone. The addition amount of the organic solvent can be selected according to the actual situation to meet the progress of the reaction.

[0072] According to some embodiments of the present invention, the reaction temperature for preparing the reactive emulsifier is 50°C to 85°C.

[0073] According to some embodiments of the present invention, the reaction time for preparing the reactive emulsifier is 2 hours to 10 hours.

[0074] The third aspect of the present invention provides the application of the reactive emulsifier described in the first aspect of the present invention in acrylic emulsion polymerization.

[0075] According to some embodiments of the present invention, the raw materials for preparing the acrylic emulsion polymerization include polymerization monomers and a reactive emulsifier;

[0076] The polymerization monomers include acrylic monomers, or acrylic monomers and other monomers containing double bonds; the acrylic monomers include at least one of acrylic acid, methacrylic acid, acrylate containing double bonds, methacrylate containing double bonds, acrylonitrile, acrylamide, N - hydroxymethylacrylamide, and hydroxyacrylate;

[0077] The other monomers containing double bonds include at least one of unsaturated dibasic acids, styrene, and vinyl acetate;

[0078] The unsaturated dibasic acids include at least one of maleic acid, itaconic acid, 2 - pentenedioic acid, and 2 - hexenedioic acid.

[0079] According to some embodiments of the present invention, the acrylate containing double bonds includes at least one of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isooctyl acrylate, lauryl acrylate, and stearyl acrylate.

[0080] According to some embodiments of the present invention, the methacrylate containing a double bond includes at least one of methyl methacrylate, ethyl methacrylate, butyl methacrylate, isooctyl methacrylate, allyl methacrylate, and isobornyl methacrylate.

[0081] According to some embodiments of the present invention, the mass of the reactive emulsifier is 0.1% to 3% of the mass of the polymerization monomers.

[0082] According to some specific embodiments of the present invention, the mass of the reactive emulsifier is 0.3% to 1.5% of the mass of the polymerization monomers.

[0083] According to some embodiments of the present invention, the raw materials for preparing the acrylic emulsion polymerization further include a buffer, an initiator, a pH regulator, and water.

[0084] According to some embodiments of the present invention, the mass of the buffer is 0.1% to 2% of the mass of the polymerization monomers.

[0085] According to some specific embodiments of the present invention, the mass of the buffer is 0.5% to 1.5% of the mass of the polymerization monomers.

[0086] According to some embodiments of the present invention, the buffer includes at least one of sodium bicarbonate, potassium bicarbonate, sodium carbonate, and potassium carbonate.

[0087] According to some embodiments of the present invention, the mass of the initiator is 0.1% to 2% of the mass of the polymerization monomers.

[0088] According to some specific embodiments of the present invention, the mass of the initiator is 0.5% to 1.5% of the mass of the polymerization monomers.

[0089] According to some embodiments of the present invention, the initiator is a persulfate, such as at least one selected from potassium persulfate, sodium persulfate, and ammonium persulfate.

[0090] According to some embodiments of the present invention, the pH regulator includes at least one of ammonia water, monoethanolamine, triethanolamine, and dimethylethanolamine.

[0091] According to some embodiments of the present invention, the mass of the water is 45% to 55% of the total mass of the raw materials for preparing the acrylic emulsion polymerization.

[0092] According to some specific embodiments of the present invention, the mass of the water is 47% to 52% of the total mass of the raw materials for preparing the acrylic emulsion polymerization.

[0093] According to some embodiments of the present invention, the water is deionized water.

[0094] According to some embodiments of the present invention, the preparation method of the acrylic emulsion polymerization comprises the following steps:

[0095] S1: Mix the polymerization monomers, a part of the reactive emulsifier, a part of the buffer, a part of the initiator and a part of the water, and stir and emulsify to obtain a pre-emulsion;

[0096] S2: Mix the remaining reactive emulsifier, buffer, initiator and water, heat to 75 - 80 °C, then add a part of the pre-emulsion, and control the temperature at 80 - 85 °C for seed polymerization reaction; then add the remaining pre-emulsion, and continue the polymerization reaction at 80 - 85 °C; then cool down, add a pH regulator and mix to obtain an acrylic emulsion.

[0097] According to some embodiments of the preparation method of the acrylic emulsion polymerization of the present invention, in the step S1, a part of the reactive emulsifier refers to the reactive emulsifier accounting for 40% - 80% of the total mass of the reactive emulsifier.

[0098] According to some specific embodiments of the preparation method of the acrylic emulsion polymerization of the present invention, in the step S1, a part of the reactive emulsifier refers to the reactive emulsifier accounting for 50% - 70% of the total mass of the reactive emulsifier.

[0099] According to some embodiments of the preparation method of the acrylic emulsion polymerization of the present invention, in the step S1, a part of the buffer refers to the buffer accounting for 10% - 50% of the total mass of the buffer.

[0100] According to some specific embodiments of the preparation method of the acrylic emulsion polymerization of the present invention, in the step S1, a part of the buffer refers to the buffer accounting for 10% - 30% of the total mass of the buffer.

[0101] According to some embodiments of the preparation method of the acrylic emulsion polymerization of the present invention, in the step S1, a part of the initiator refers to the initiator accounting for 40% - 80% of the total mass of the initiator.

[0102] According to some embodiments of the preparation method of the acrylic emulsion polymerization of the present invention, in the step S1, a part of the water refers to the water accounting for 30% - 50% of the total mass.

[0103] According to some embodiments of the preparation method of the acrylic emulsion polymerization of the present invention, in the step S1, the stirring rate for stirring and emulsifying is 2000 rpm - 3000 rpm.

[0104] According to some embodiments of the preparation method of the acrylic emulsion polymerization of the present invention, in the step S1, the time for stirring and emulsifying is 20 minutes - 40 minutes.

[0105] According to some embodiments of the preparation method of acrylic emulsion polymerization of the present invention, in the step S2, a part of the pre-emulsion refers to the pre-emulsion accounting for 5% to 10% of the total mass of the pre-emulsion.

[0106] According to some embodiments of the preparation method of acrylic emulsion polymerization of the present invention, in the step S2, the specific operation of controlling the temperature at 80 - 85 °C for seed polymerization reaction is: controlling the temperature at 80 - 85 °C for reaction, and when the reaction temperature reaches the highest temperature in the range of 80 - 85 °C, timing the reaction for 30 - 40 minutes.

[0107] According to some embodiments of the preparation method of acrylic emulsion polymerization of the present invention, in the step S2, the specific steps of adding the remaining pre-emulsion and continuing the polymerization reaction at 80 - 85 °C are: maintaining the temperature at 78 °C - 82 °C, adding the remaining pre-emulsion dropwise in 3 - 4 hours, and then reacting at 80 °C - 85 °C for 1.5 - 2.5 hours.

[0108] According to some embodiments of the preparation method of acrylic emulsion polymerization of the present invention, in the step S2, cooling means cooling to 40 °C or below.

[0109] According to some embodiments of the preparation method of acrylic emulsion polymerization of the present invention, in the step S2, adding a pH regulator is to adjust the pH of the system to neutral, and in actual operation, the pH value of the system can be controlled at 7 ± 0.2.

[0110] According to some embodiments of the preparation method of acrylic emulsion polymerization of the present invention, after adding the pH regulator and mixing, the steps of filtration and discharging are further included. In some embodiments, the filtration is carried out through a filter screen with 180 - 220 meshes.

[0111] In some specific embodiments of the present invention, the preparation method of acrylic emulsion polymerization includes the following steps:

[0112] 1) Add the formulated amount of polymerization monomers, part of the reactive emulsifier, part of the buffer, part of the initiator and part of the water into the reactor, stir and emulsify at a speed of 2000 - 3000 rpm for 20 - 40 minutes to obtain a pre-emulsion;

[0113] 2) Add the remaining water, the remaining initiator, the remaining buffer and the remaining reactive emulsifier into the reactor, stir evenly, heat up to 75 - 80 °C, add 5 - 10% of the total mass of the pre-emulsion prepared in step 1), and control the temperature at 80 - 85 °C for seed polymerization reaction;

[0114] 3) When the temperature in the reactor reaches the highest temperature between 80 and 85 °C, start timing the reaction for 30 to 40 minutes, add the remaining pre-emulsion dropwise, keep the temperature during the dropwise addition at 80 to 85 °C, finish dropping in 3 to 4 hours, and then react at 80 to 85 °C for 1.5 to 2.5 hours;

[0115] 4) When the temperature in the kettle is lowered to 40 °C, add a pH regulator, stir evenly, filter through a 200-mesh filter screen and discharge to obtain an acrylic emulsion.

[0116] The fourth aspect of the present invention provides an acrylic emulsion, which is prepared from raw materials including the reactive emulsifier described in the first aspect of the present invention.

[0117] According to some embodiments of the present invention, for other raw materials for preparing the acrylic emulsion, such as polymerization monomers, and processing reagents (buffer, initiator, pH regulator and water) and preparation methods, etc., refer to the relevant content of the application in the foregoing third aspect.

[0118] The fifth aspect of the present invention provides the application of the acrylic emulsion prepared by the application described in the third aspect of the present invention, or the acrylic emulsion described in the fourth aspect of the present invention in the preparation of waterborne acrylic products, and the waterborne acrylic products include waterborne acrylic coatings, waterborne acrylic paper brighteners, waterborne acrylic fabric finishing agents, waterborne acrylic pressure-sensitive adhesives, waterborne acrylic leather treatment liquids, waterborne acrylic amino baking varnishes or waterborne acrylic polyurethane baking varnishes.

[0119] According to some embodiments of the present invention, the waterborne acrylic products include single-component and two-component waterborne acrylic products. For example, the waterborne acrylic coating can be a single-component waterborne acrylic coating and a two-component waterborne acrylic coating, and the waterborne acrylic polyurethane baking varnish can be a single-component waterborne acrylic polyurethane baking varnish and a two-component waterborne acrylic polyurethane baking varnish, etc. The acrylic emulsion prepared by using the reactive emulsifier of the present invention is applicable to single-component and two-component waterborne acrylic products.

[0120] The beneficial effects of the present invention are:

[0121] The present invention provides a reactive emulsifier for acrylic emulsion polymerization, which not only has a very high emulsification efficiency and maintains the stability of the emulsification system, but also the reactive functional groups in its structure can participate in the free radical system copolymerization and become a part of the acrylic resin structure, avoiding the desorption of the adsorption-type emulsifier from the polymer particles or the migration in the latex film, reducing the concentration of emulsifier molecules on the surface of the emulsion particles, thereby improving the stability of the emulsion and enhancing the water resistance, strength, light and heat resistance and other properties of the latex film.

[0122] Specifically, compared with the prior art, the present invention has the following advantages:

[0123] 1. There is no residual free emulsifier. The reactive emulsifier of the present invention can participate in the free radical copolymerization of acrylic monomers and become a part of the acrylic resin structure. There is no free single-molecule emulsifier, which not only has no impact on the product performance, but also can improve various properties of the acrylic resin.

[0124] 2. The emulsion has good stability. The hydrophilic group of the reactive emulsifier of the present invention is an anionic sulfonate group, with high emulsification efficiency, which can effectively reduce the surface tension. The latex particles are small in size and have good mechanical stability. In practical applications, different types of emulsifiers can be selected according to the product performance requirements to meet the performance needs of different products and make the emulsion have good stability.

[0125] 3. It has a wide range of applications. The reactive emulsifier of the present invention can be divided into four structures: A, B, C, and D. It can introduce the required functional groups and / or segments into the acrylic resin, endowing the acrylic resin with more excellent properties to meet the needs of different performances of various acrylic emulsions.

[0126] 4. It is suitable for the emulsion polymerization of single-component and two-component acrylic resins. The reactive emulsifier of the present invention has entered the acrylic resin structure during the acrylic emulsion polymerization stage, so the emulsion prepared by it is suitable for the uses of single-component and two-component acrylic resins.

[0127] 5. It solves the problem of air bubbles in high-speed coating. For the acrylic emulsion prepared with traditional emulsifiers, due to the existence of emulsifiers with low surface tension, a large amount of foam is generated during the rotation of the roller during high-speed coating, which not only makes the coating difficult, but also causes problems such as insufficient sizing amount, air bubble imprints on the glue surface, and surface pores. The acrylic emulsion prepared with the reactive emulsifier of the present invention has no free emulsifier, greatly reducing the foam generated by the roller during coating, improving the surface quality of the coated product, and greatly enhancing the quality of the product; secondly, it also reduces the formation of emulsion foam during transportation, making transportation more convenient. Specific embodiments

[0128] The content of the present invention will be further described in detail through specific embodiments below. The raw materials, reagents or devices used in the examples and comparative examples can be obtained from conventional commercial channels or can be obtained by existing technical methods without special instructions. Unless otherwise specified, the test or testing methods are conventional methods in the art, and the percentages used all represent mass percentages.

[0129] The raw materials used in the examples are described as follows:

[0130] 1. SSTD-80 waterborne diisocyanate (sulfonate-modified TDI) is produced by Foshan Jingxin Huiming Technology Co., Ltd., with a solid content of 80%, a viscosity of 5200 mPa·s / 25°C, and an NCO content of 14.89%. The preparation method of SSTD-80 waterborne diisocyanate can be referred to Example 3 described in paragraphs

[0101] -

[0104] of the specification of CN111423343A, and the solid content, viscosity, and NCO content are slightly adjusted during actual production.

[0131] 2. SSIPD-75 waterborne diisocyanate (sulfonate-modified IPDI) is produced by Foshan Jingxin Huiming Technology Co., Ltd., which is a slightly yellow viscous liquid, with a solid content of 75.2%, a viscosity of 6500 mPa·s / 25°C, and an NCO content of 12.5%. The preparation method of SSIPD-75 waterborne diisocyanate can be referred to Example 1 described in paragraphs

[0091] -

[0096] of the specification of CN111423343A, and the solid content, viscosity, and NCO content are slightly adjusted during actual production.

[0132] 3. SSFB-75 reactive emulsifier is produced by Foshan Jingxin Huiming Technology Co., Ltd. One end of the emulsifier structure has a double bond and the other end has a hydroxyl group. The active ingredient is 75%, the viscosity is 2600 mPa·s / 25°C, and the hydroxyl value (mgKOH / g) is 47.5. SSFB-75 reactive emulsifier is prepared using polyethylene glycol PEG 400 as the raw material. Its preparation method can be referred to Example 3 described in paragraphs

[0119] -

[0123] of the specification of CN115926105A, and the viscosity and hydroxyl value are slightly adjusted during actual production.

[0133] The structural formula of this emulsifier is as follows:

[0134]

[0135] Among them, X is a double bond, CH2=;

[0136] R is an alkylene chain containing a urethane group;

[0137] R’ is

[0138] R” is H;

[0139] n = 3 - 30.

[0140] 4. HDX-100 waterborne polyurethane curing agent is produced by Foshan Jingxin Huiming Technology Co., Ltd., with a solid content of 100%, an NCO content of 21.2%, and a viscosity of 6500 mPa·s / 25°C.

[0141] 5. The HDX-600 self-drying waterborne curing agent is produced by Foshan Jingxin Huiming Technology Co., Ltd., with a solid content of 92%, an NCO content of 19.5%, and a viscosity of 2300 mPa·s / 25°C.

[0142] 6. Covestro waterborne blocked curing agent Imprafix 2794XP, with a solid content of 39 - 41%, a viscosity (23°C) < 1500 mPa·s, a pH value (20°C) of 6.5 - 8.5, and an NCO content (blocked) of 5.0%.

[0143] The test methods are described as follows:

[0144] 1. Appearance (visual inspection) is carried out according to "GB / T 1721-2008 Determination of the Appearance and Transparency of Clear Varnishes, Clear Oils and Thinners".

[0145] 2. The solid content is detected according to "GB / T 1725-2007 Determination of the Non-Volatile Content of Paints, Varnishes and Plastics".

[0146] 3. The viscosity is detected according to "GB / T 2794-2022 Determination of the Viscosity of Adhesives", and unless otherwise specified, the test temperature of the viscosity is 25°C.

[0147] 4. The hydroxyl value is detected according to "HG / T 2709-2022 Determination of the Hydroxyl Value of Polyester Polyols for the Production of Polyurethanes in Plastics".

[0148] 5. The NCO content is detected according to "HG / T 2409-2023 Determination of the Isocyanate Group Content in Polyurethane Prepolymers".

[0149] Example 1

[0150] Preparation of Reactive Emulsifier A

[0151] Add 100 g of SSTD-80, 3.5 g of propylene glycol methyl ether acetate, and 0.08 g of phosphoric acid into a four-necked flask equipped with an electric stirrer, a reflux condenser, a thermometer and a dropping device, stir evenly, then add 52.6 g of hydroxypropyl methacrylate, stir, the temperature in the flask rises, after the natural temperature rise stops, heat to 60°C and react for 2 h, react at 70°C for 2 h, react at 80°C for 2 h, then take samples every 0.5 h to measure the NCO content, stop the reaction when no NCO can be detected, cool down and discharge to obtain reactive emulsifier A.

[0152] The structural formula of reactive emulsifier A is shown as formula (a):

[0153]

[0154] In formula (a), R3 is an alkylene chain containing a urethane group.

[0155] After testing, the appearance of this emulsifier is a slightly yellowish viscous liquid, the solid content is 85%, and the viscosity is 7500 mPa·s / 25°C.

[0156] Example 2

[0157] Preparation of Reactive Emulsifier B

[0158] 1) Add 100 g of SSIPDI-75 and 6.8 g of absolute ethanol into a four-necked flask equipped with an electric stirrer, reflux condenser, thermometer and dropping device, stir, and after the natural temperature rise stops, heat up to 70°C and react for 2 h, then heat up to 80°C and react for 2 h. After that, take samples every 0.5 h to measure the NCO content. When it is close to 5.8%, cool down to 50°C;

[0159] 2) Add 10 g of propylene glycol methyl ether acetate, 0.08 g of phosphoric acid and 21.4 g of hydroxypropyl methacrylate into the flask. After the temperature in the flask no longer rises naturally, heat up to 60°C and react for 2 h, 70°C and react for 2 h, 80°C and react for 2 h. After that, take samples every 0.5 h to measure the NCO content. Stop the reaction when no NCO is detected, cool down and discharge to obtain reactive emulsifier B.

[0160] The structural formula of reactive emulsifier B is shown in formula (b):

[0161]

[0162] In formula (b), R3 is an alkylene chain containing a urethane group.

[0163] After testing, the appearance of this emulsifier is a slightly yellowish viscous liquid, the solid content is 75%, and the viscosity is 7100 mPa·s / 25°C.

[0164] Example 3

[0165] Preparation of Reactive Emulsifier C

[0166] 1) Add 100 g of SSTD-80, 10 g of propylene glycol methyl ether acetate, and 0.08 g of phosphoric acid into a four-necked flask equipped with an electric stirrer, reflux condenser, thermometer and dropping device, stir evenly, then add 25.5 g of hydroxypropyl methacrylate, stir, and after the natural temperature rise stops, heat up to 60°C and react for 2 h, 70°C and react for 2 h, 80°C and react for 2 h. After that, take samples every 0.5 h to measure the NCO content. When it is close to 5.4%, cool down to 50°C;

[0167] 2) Add 11.5 g of propylene glycol methyl ether acetate into the bottle and stir evenly. Then add 60 g of dihydroxy silicone oil (average molecular weight is 340). After the temperature no longer rises naturally, heat it to 50 °C and react for 1 h, then react at 60 °C for 1 h. Stop the reaction when no NCO can be detected, cool down and discharge to obtain reactive emulsifier C.

[0168] The structural formula of reactive emulsifier C is shown in formula (c):

[0169]

[0170] In formula (c), R3 is an alkylene chain containing a urethane group; n = 2 - 3.

[0171] After testing, the appearance of this emulsifier is a slightly yellow viscous liquid, the solid content is 80%, the viscosity is 4900 mPa·s / 25 °C, and the hydroxyl value is 47.5 mgKOH / g.

[0172] Example 4

[0173] Preparation of Reactive Emulsifier D

[0174] 1) Add 100 g of SSIPDI - 75, 10 g of propylene glycol methyl ether acetate, and 0.08 g of phosphoric acid into flask No. 1 and stir evenly. Then add 19.3 g of hydroxypropyl acrylate and stir. The temperature in the flask rises. After it no longer rises naturally, heat it to 60 °C and react for 2 h, react at 70 °C for 2 h, react at 80 °C for 2 h. Then take samples every 0.5 h to measure the NCO content. When it is close to 5.2%, cool it down to 50 °C for standby.

[0175] 2) Add 56.4 g of sodium 2 - aminoethanesulfonate (aqueous solution with a solid content of 50%) and 18 g of deionized water into flask No. 2. With the cooling water on, slowly add the standby solution prepared in step 1), control the temperature during the addition of the standby solution not to exceed 50 °C, then react at 50 °C for 1 h, heat up to 65 °C and react for 1 h, cool down to room temperature and discharge to obtain reactive emulsifier D.

[0176] The structural formula of reactive emulsifier D is shown in formula (d):

[0177]

[0178] In formula (d), R3 is an alkylene chain containing a urethane group.

[0179] After testing, the appearance of this emulsifier is a slightly yellow viscous liquid, the solid content is 60%, and the viscosity is 6700 mPa·s / 25 °C.

[0180] Example 5

[0181] In this example, reactive emulsifier A is used as the emulsifier in the polymerization of acrylic emulsion. The preparation method of the acrylic emulsion is as follows:

[0182] 1) Preparation of monomer pre-emulsion

[0183] Add 145 g of deionized water, 1.6 g of reactive emulsifier A prepared in Example 1, 1.6 g of ammonium persulfate, 0.4 g of sodium bicarbonate, 32 g of methyl methacrylate, 12.8 g of hydroxypropyl acrylate, 320 g of n-butyl acrylate, 32 g of isooctyl acrylate, and 3.2 g of acrylic acid into an emulsifier, and stir and emulsify at a speed of 2000 - 3000 rpm for 30 min to obtain a mixed monomer pre-emulsion.

[0184] 2) Seed polymerization reaction

[0185] Add 260 g of deionized water, 1.6 g of reactive emulsifier A prepared in Example 1, 2.0 g of ammonium persulfate, and 3.2 g of sodium bicarbonate into a four-necked flask equipped with an electric stirrer, a reflux condenser, a thermometer, and a dropping device. Stir and heat up to 75 - 80 °C, then add 50 g of the mixed monomer pre-emulsion prepared in step 1), and control the temperature at 80 - 85 °C for the seed polymerization reaction.

[0186] 3) Preparation of acrylic emulsion

[0187] When the temperature in the reaction flask reaches the highest, start timing for 40 minutes, and then start dropping the remaining mixed monomer pre-emulsion, keeping the temperature during the dropping process at 78 - 82 °C. Finish dropping in 3.5 h, and then react at 80 - 85 °C for 2 h.

[0188] 4) Discharging

[0189] Cool down to 40 °C, adjust the pH of the system to 7 with ammonia water, stir evenly, and then filter through a 200-mesh filter screen for discharging to obtain an acrylic emulsion with a milky white appearance and blue light.

[0190] After detection, the pH value of the acrylic emulsion in this example is 7.1, the viscosity is 2430 mPa·s, the solid content is 50.1%, and the hydroxyl value is 6.8 mg KOH / g.

[0191] Comparative Example 1

[0192] Use ammonium nonylphenol polyoxyethylene ether sulfate and nonylphenol polyoxyethylene ether (10) as the mixed emulsifiers for preparing acrylic emulsion. The preparation method of the acrylic emulsion is as follows:

[0193] 1) Preparation of monomer pre-emulsion

[0194] Add 145 g of deionized water, 1.2 g of ammonium nonylphenol polyoxyethylene ether sulfate, 0.4 g of nonylphenol polyoxyethylene ether (10), 1.6 g of ammonium persulfate, 0.4 g of sodium bicarbonate, 32 g of methyl methacrylate, 12.8 g of hydroxypropyl acrylate, 320 g of n-butyl acrylate, 32 g of isooctyl acrylate and 3.2 g of acrylic acid into an emulsifier, and stir and emulsify at a speed of 2000 - 3000 rpm for 30 min to obtain a mixed monomer pre-emulsion.

[0195] 2) Seed polymerization reaction

[0196] Add 260 g of deionized water, 1.2 g of ammonium nonylphenol polyoxyethylene ether sulfate, 0.4 g of nonylphenol polyoxyethylene ether (10), 2.0 g of ammonium persulfate, and 3.2 g of sodium bicarbonate into a four-necked flask equipped with an electric stirrer, a reflux condenser, a thermometer and a dropping device. Stir and heat up to 75 - 80 °C, then add 50 g of the mixed monomer pre-emulsion prepared in step 1), and control the temperature at 80 - 85 °C to carry out the seed polymerization reaction.

[0197] 3) Preparation of acrylic emulsion

[0198] When the temperature in the reaction flask reaches the highest, start timing for 40 minutes, and then start dropping the remaining mixed monomer pre-emulsion, keeping the temperature during the dropping process at 78 - 82 °C. Finish dropping in 3.5 h, and then react at 80 - 85 °C for 2 h.

[0199] 4) Discharging

[0200] Cool down to 40 °C, adjust the system to pH 7 with ammonia water, add 0.4 g of 691 mineral oil defoamer, stir evenly, and then filter through a 200-mesh sieve to discharge, obtaining an acrylic emulsion with a milky white appearance and blue light.

[0201] After testing, the pH value of the acrylic emulsion in this example is 7.1, the viscosity is 3530 mPa·s, the solid content is 50.1%, and the hydroxyl value is 6.8 mg KOH / g.

[0202] Application Example 1

[0203] Add 1% of HDX-600 air-drying waterborne curing agent based on the weight of the emulsion and 4 times the weight of the emulsion of deionized water into the acrylic emulsions prepared in Example 5 and Comparative Example 1 respectively, mix and stir evenly to obtain the waterborne acrylic pressure-sensitive adhesive of Example 5 and the waterborne acrylic pressure-sensitive adhesive of Comparative Example 1. Coat the two prepared pressure-sensitive adhesives on a 90-μm-thick PE film respectively, and the dry coating amount is 3 ± 1 g / m 2 .

[0204] The properties of the two pressure-sensitive adhesives are shown in Table 1. The test methods in Table 1 are described as follows: The initial tack is according to GB / T 4852-2002, and the 180° peel strength is according to GB / T 2792-2014.

[0205] Table 1 Comparison of the performance effects of the pressure-sensitive adhesives in Example 5 and Comparative Example 1

[0206]

[0207] The experimental results according to Table 1 show that: The pressure-sensitive adhesive prepared with the reactive emulsifier A of the present invention in Example 5 has higher strength performance, better water resistance, coating performance and product surface quality than the pressure-sensitive adhesive prepared with the polyoxyethylene ether emulsifier in Comparative Example 1. Because the polyoxyethylene ether emulsifier has a low surface tension and is prone to generating bubbles. Although an antifoaming agent was added in Comparative Example 1, a large amount of foam was still generated during the rotation of the roller during high-speed coating, which limited the coating speed and left fine shrink marks on the surface of the coated object due to the bursting of the bubbles.

[0208] Example 6

[0209] In this example, the reactive emulsifier B is used as the emulsifier in the polymerization of the acrylic emulsion. The preparation method of the acrylic emulsion is as follows:

[0210] 1) Preparation of monomer pre-emulsion

[0211] Add 120 g of deionized water, 1.4 g of the reactive emulsifier B prepared in Example 2, 1.6 g of ammonium persulfate, 0.4 g of sodium bicarbonate, 160 g of methyl methacrylate, 60 g of ethyl methacrylate, 48 g of butyl acrylate, 40 g of hydroxypropyl methacrylate, 88 g of styrene and 4 g of acrylic acid into the emulsifier, and stir and emulsify at a speed of 2000 - 3000 rpm for 30 min to obtain a mixed monomer pre-emulsion.

[0212] 2) Seed polymerization reaction

[0213] Add 250 g of deionized water, 1.4 g of the reactive emulsifier B prepared in Example 2, 2.0 g of ammonium persulfate, and 3.2 g of sodium bicarbonate into a four-necked flask equipped with an electric stirrer, a reflux condenser, a thermometer and a dropping device. Stir and heat up to 75 - 80 °C, then add 35 g of the mixed monomer pre-emulsion prepared in step 1), and control the temperature at 80 - 85 °C to carry out the seed polymerization reaction.

[0214] 3) Preparation of acrylic emulsion

[0215] When the temperature in the reaction flask reaches the highest, start timing for 35 minutes, and start dropping the remaining mixed monomer pre-emulsion, keeping the temperature during the dropping process at 78 - 82 °C, and finishing dropping in 3.5 h. Then, react at 80 - 85 °C for 2 h.

[0216] 4) Discharging

[0217] Cool down to 40°C, adjust the pH of the system to 7 with ammonia water. After stirring evenly, filter through a 200-mesh filter and discharge to obtain an acrylic emulsion with a milky white appearance and blue light.

[0218] After testing, the pH value of the acrylic emulsion in this example is 7.2, the viscosity is 2760 mPa·s, the solid content is 50.2%, and the hydroxyl value is 19.2 mg KOH / g.

[0219] Application Example 2

[0220] The acrylic emulsion of Example 2 and a waterborne blocked isocyanate curing agent form a two-component waterborne polyurethane-modified acrylic baking paint. Its preparation method includes the following steps:

[0221] Take 200 g of the acrylic emulsion of Example 2, add 50 g of the waterborne blocked curing agent Imprafix 2794XP, and mix and stir evenly to obtain a waterborne baking paint.

[0222] Apply this baking paint on a tinplate sample, cure it in an oven at 180°C for 60 minutes, and let it stand at room temperature for 24 hours. The performance of the obtained paint film is as follows: The appearance of the paint film (visual inspection) is smooth and flat; Gloss (60°): ≥95%; Hardness: Shore D56; Impact strength: 58 KJ / m 2 ; Adhesion: Grade 1; Flexibility: 1 mm; Water resistance (72 h) is normal.

[0223] The test methods are described as follows: Gloss (60°) is in accordance with GB / T 9754-2007, hardness is in accordance with GB / T 1730-2007, impact strength is in accordance with GB / T 1732-2020, adhesion is in accordance with GB / T 1720-2020, flexibility is in accordance with GB / T 1731-2020, and water resistance is in accordance with GB / T1733-1993.

[0224] Example 7

[0225] In this example, a reactive emulsifier C is used as the emulsifier in the polymerization of the acrylic emulsion. The preparation method of the acrylic emulsion is as follows:

[0226] 1) Prepare the monomer pre-emulsion

[0227] Add 140 g of deionized water, 1.2 g of the reactive emulsifier C prepared in Example 3, 1.8 g of ammonium persulfate, 0.4 g of sodium bicarbonate, 200 g of methyl methacrylate, 60 g of isobornyl methacrylate, 60 g of butyl methacrylate, 32 g of hydroxypropyl acrylate, 40 g of n-butyl acrylate, and 8 g of methacrylic acid into an emulsifier, and stir and emulsify at a speed of 2000-3000 rpm for 30 minutes to obtain a mixed monomer pre-emulsion.

[0228] 2) Seed polymerization reaction

[0229] In a four-necked flask equipped with an electric stirrer, a reflux condenser, a thermometer and a dropping device, add 260 g of deionized water, 1.8 g of the reactive emulsifier C prepared in Example 3, 2.0 g of ammonium persulfate, and 3.2 g of sodium bicarbonate. Stir and heat up to 75 - 80 °C, then add 40 g of the mixed monomer pre-emulsion prepared in step 1), and carry out seed polymerization reaction while controlling the temperature at 80 - 85 °C.

[0230] 3) Preparation of acrylic emulsion

[0231] When the temperature in the reaction flask reaches the highest, start timing for 40 minutes, then start dropping the remaining mixed monomer pre-emulsion, keep the temperature during the dropping process at 78 - 82 °C, finish dropping in 3.5 h, and then react at 80 - 85 °C for 2 h.

[0232] 4) Discharging

[0233] Cool down to 40 °C, adjust the system to pH 7 with ammonia water, stir evenly, then filter through a 200-mesh filter and discharge to obtain an acrylic emulsion with a milky white appearance and blue light.

[0234] After testing, the pH value of the acrylic emulsion in this example is 7.3, the viscosity is 3240 mPa·s, the solid content is 50.1%, and the hydroxyl value is 17.2 mgKOH / g.

[0235] Application Example 3

[0236] 1) Preparation of two-component waterborne polyurethane-modified acrylic coating

[0237] Take 200 g of the acrylic emulsion prepared in Example 7, add 30 g of HDX-100 waterborne polyurethane curing agent, mix and stir evenly to obtain a polyurethane-modified acrylic coating. Apply this coating on a tinplate sample, cure at 50 - 60 °C for 72 hours, and after standing at room temperature for 24 hours, test the film properties as follows: film appearance (visual inspection) is flat and smooth; gloss (60°): ≥90%; hardness: Shore D50; impact strength: 52 KJ / m 2 ; adhesion: grade 1; flexibility: 1 mm; water resistance (72 h) is normal.

[0238] 2) Preparation of one-component waterborne acrylic coating

[0239] Take 200 g of the acrylic emulsion prepared in Example 7, add 10 g of silver paste, mix and stir evenly to obtain an acrylic coating. Coat the coating on a PET film, dry it, and after standing at room temperature for 48 hours, test the coating properties as: coating layer appearance (visual inspection) is flat and smooth; adhesion is grade 1; water resistance (96 h) is normal.

[0240] Comparative Example 2

[0241] This example provides a method of first preparing a solvent-based acrylic resin, then adding the reactive polyurethane anionic-nonionic emulsifier SSFB-75 disclosed in CN115926105A to disperse it into an acrylic resin emulsion, and then preparing a two-component coating and a one-component coating, and comparing the properties of the two to illustrate the scope of use and performance characteristics of the reactive polyurethane anionic-nonionic emulsifier SSFB-75 as an external emulsifier, so as to further illustrate the difference between the reactive emulsifier of this application and the reactive polyurethane anionic-nonionic emulsifier disclosed in CN115926105A.

[0242] A. The method for preparing the acrylic resin emulsion is as follows:

[0243] 1) Preparation of the solvent-based acrylic resin

[0244] a. Mix 50 g of methyl methacrylate, 12 g of isobornyl methacrylate, 12 g of butyl methacrylate, 8 g of hydroxypropyl acrylate, 10 g of n-butyl acrylate, 2 g of methacrylic acid, and 0.5 g of benzoyl peroxide to obtain a monomer mixture.

[0245] b. Add 70 g of ethyl acetate and 0.2 g of benzoyl peroxide to a four-necked reaction flask, mix evenly, heat up to 75-80 °C, add 10 g of the monomer mixture, control the temperature at 80-85 °C for the polymerization reaction. When the temperature in the flask reaches the highest, time for 40 minutes, dropwise add the remaining monomer mixture, keep the temperature during the dropping process at 78-82 °C, finish dropping in 3.5 h, and then react at 80-85 °C for 3 h. Cool down to 70 °C, add 30 g of ethyl acetate, stir evenly to obtain a light yellow transparent liquid, which is the solvent-based acrylic resin. Take a sample and detect that the resin solid content is 50.1% and the hydroxyl value is 17.1 mgKOH / g.

[0246] 2) Adding an external emulsifier to prepare the acrylic resin emulsion

[0247] Continue to add 8 g of the SSFB-75 reactive emulsifier and 100 g of deionized water to the reaction flask, stir and disperse at 1000 revolutions per minute for 30 minutes to obtain a milky white aqueous acrylic resin emulsion with a blue light. After detection, the solid content of this emulsion is 33.8%, the viscosity is 3240 mPa·s, and the hydroxyl value is 11.5 mgKOH / g.

[0248] B. Preparation of a two-component waterborne polyurethane-modified acrylic coating

[0249] Take 100 g of the acrylic resin emulsion prepared in A above, add 15 g of HDX-100 waterborne polyurethane curing agent, mix and stir evenly to obtain a polyurethane-modified acrylic waterborne coating. Apply this coating on a tinplate sample, cure at 50-60 °C for 72 hours, and place at room temperature for 24 hours. Then test the film properties as follows: The film appearance (visual inspection) is flat and smooth; Gloss (60°): ≥90%; Hardness: Shore D48; Impact strength: 55 KJ / m 2 ; Adhesion: Grade 1; Flexibility: 1 mm; Water resistance (72 h) is normal.

[0250] C. Preparation of a one-component waterborne acrylic coating

[0251] Take 100 g of the acrylic resin emulsion prepared in A above, add 5 g of silver paste, mix and stir evenly to obtain an acrylic silver paste coating. Coat this coating on a PET film, dry it, and place it at room temperature for 48 hours. Then test the coating properties: The appearance of the paint layer (visual inspection) has a few dented points; Adhesion is Grade 2; Water resistance (96 h) shows whitening and foaming.

[0252] The test results of the two-component waterborne polyurethane-modified acrylic coating prepared in B above and the one-component waterborne acrylic coating prepared in C show that: For the acrylic emulsion prepared with the reactive polyurethane anionic-nonionic emulsifier SSFB-75, it must be cured by adding a polyurethane curing agent before it has no effect on the product performance. Because it is an externally added reactive emulsifier, although one end of it has a double bond and the other end has a hydroxyl group, if it is not crosslinked with the curing agent, its active groups do not play a role. It is dispersed in the acrylic emulsion, in a free state, and remains in the product in an adsorbed form, easily migrating to the surface and forming a non-covalently bonded emulsifier layer on the film surface. Once exposed to water or moisture, it will cause the adhesive film to absorb water and swell, resulting in "blooming", "whitening", and a decrease in strength performance. Therefore, the reactive polyurethane anionic-nonionic emulsifier disclosed in CN115926105A is only suitable for the emulsification of two-component solvent-based resins, and not for the emulsification of one-component solvent-based resins. Similarly, the reactive polyurethane anionic emulsifier disclosed in CN115926106A is also only suitable for the emulsification of two-component solvent-based resins.

[0253] The test results of steps 1) and 2) in Application Example 3 and those of Tests B and C in Comparative Example 2 also show that: the reactive emulsifier of the present application is an internal emulsifier, and the emulsifier molecules copolymerize with acrylic monomers and become part of the acrylic resin structure. Therefore, the acrylic emulsion prepared in Example 7 has a certain applicable range whether or not a curing agent is added. The reactive polyurethane anionic-nonionic emulsifier disclosed in CN115926105A and the reactive polyurethane anionic emulsifier disclosed in CN115926106A are external emulsifiers. The acrylic emulsions prepared with them can only be used in the two-component curing form with an isocyanate curing agent as a supporting agent. Because although the external emulsifier molecules also carry hydroxyl groups, if no isocyanate curing agent is added, they still exist in the product in a free state, which affects the product performance. Therefore, the reactive emulsifiers disclosed in these two patents are only applicable to the emulsification of two-component solvent-based resins, and not to the emulsification of one-component solvent-based resins.

[0254] Example 8

[0255] In this example, reactive emulsifier D was used as the emulsifier in the polymerization of acrylic emulsion. The preparation method of the acrylic emulsion was as follows:

[0256] 1) Preparation of monomer pre-emulsion

[0257] 150 g of deionized water, 1.0 g of reactive emulsifier D prepared in Example 4, 2.0 g of ammonium persulfate, 0.4 g of sodium bicarbonate, 80 g of methyl methacrylate, 72 g of butyl methacrylate, 12 g of hydroxypropyl acrylate, 112 g of n-butyl acrylate, 120 g of ethyl acrylate, and 4 g of acrylic acid were added to an emulsifier, and stirred and emulsified at a speed of 2000 - 3000 rpm for 30 min to obtain a mixed monomer pre-emulsion.

[0258] 2) Seed polymerization reaction

[0259] 250 g of deionized water, 1.0 g of reactive emulsifier D prepared in Example 4, 2.0 g of ammonium persulfate, and 3.2 g of sodium bicarbonate were added to a four-necked flask equipped with an electric stirrer, a reflux condenser, a thermometer, and a dropping device. The mixture was stirred and heated to 75 - 80 °C, and then 60 g of the mixed monomer pre-emulsion prepared in step 1) was added. The seed polymerization reaction was carried out while controlling the temperature at 80 - 85 °C.

[0260] 3) Preparation of acrylic emulsion

[0261] When the temperature in the reaction flask reached the highest, timing started for 40 minutes, and the remaining mixed monomer pre-emulsion was started to be dropped. The temperature during the dropping process was maintained at 78 - 82 °C and finished dropping in 3.5 h, and then reacted at 80 - 85 °C for 2 h.

[0262] 4) Discharging

[0263] Cool down to 40°C, adjust the pH of the system to 7 with ammonia water. After stirring evenly, filter through a 100-mesh filter and discharge to obtain an acrylic emulsion with a milky white appearance and blue light. The pH value of the emulsion is detected to be 7.2, the viscosity is 3360 mPa·s, the solid content is 50.3%, and the hydroxyl value is 6.1 mgKOH / g.

[0264] In this example, an emulsifier with an amino group at one end is used. The amino group can form an ammonium salt with good hydrophilicity with the carboxyl group in the acrylic resin, increasing the hydrophilic groups in the system and making the emulsion more stable. Therefore, the amount of reactive emulsifier added can be reduced (the addition amount in this example is 0.5% of the monomer weight), which is suitable for the special product requirements with less emulsifier amount.

[0265] Application Example 4

[0266] This application example provides an aqueous acrylic composite adhesive, and its preparation method includes the following steps:

[0267] Take 200 g of the acrylic emulsion from Example 8, add 20 g of HDX-600 self-drying aqueous curing agent, mix and stir evenly to obtain an aqueous acrylic composite adhesive. Use this adhesive for the lamination of PET aluminized film and CPP film. Coat the adhesive on the CPP film, place it in an 80°C oven for 10 min, take it out, laminate the PET aluminized film on it, and perform rolling hot lamination at a roll temperature of 80 - 90°C. After standing at room temperature for 72 hours, conduct a 180°C peel strength test according to GB / T 2791-1995 "Test Method for T Peel Strength of Adhesives Flexible Material to Flexible Material", and the PET aluminized film is torn.

[0268] In summary, the present invention provides a reactive emulsifier, which is mainly used as an emulsifier for acrylic emulsion polymerization. It not only has good emulsifying function, but also because the double bond in the molecular structure can carry out free radical copolymerization with acrylic monomers and become a part of the resin structure, so it has no impact on the product performance, and even can improve the performance of some products. The application of the reactive emulsifier of the present invention in acrylic emulsion polymerization improves the quality of acrylic emulsion. Since there is no escape of free small molecule emulsifier during the use of the emulsion, it improves the problems such as a large number of bubbles generated during the coating of acrylic emulsion, poor surface quality of the product, decreased water resistance, and low strength performance. Therefore, the reactive emulsifier of the present invention is a new type of emulsifier widely applicable to acrylic emulsion polymerization, solving the problems such as the decline of product performance caused by the residue of adsorption-type emulsifier in acrylic products. This reactive emulsifier has good application prospects for the development of acrylic emulsion.

[0269] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A reactive emulsifier, characterized in that, Prepared from raw materials including a hydrophilic diisocyanate containing a sulfonate group and a hydroxyacrylate, and the following optional raw materials: a blocking agent, a hydroxy compound or a diamine; the blocking agent is a hydrogen-containing compound; the hydroxy compound includes a diol, an alkoxy alcohol or a hydroxy-terminated siloxane; The structural general formula of the reactive emulsifier is shown in formula (I): In formula (I), M is an alkali metal ion or an ammonium ion, and m is 1 - 6; R1 is -O-R5, or -O-R6-OH, or -O-R6-H, or an amino group; R2 is H or -CH3; R3 is an alkylene chain containing a urethane group; R4 is a hydrocarbon group of C n H 2n , and n is 2 or 3; R5 is a group other than the active hydrogen of the blocking agent; R6 is a hydrocarbon group, or an alkoxy group, or a siloxane group.

2. A reactive emulsifier according to claim 1, wherein The hydroxyacrylate includes at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate; And / or, the blocking agent includes at least one of methanol, ethanol, isopropanol, methyl ethyl ketoxime, acetone oxime, methyl isobutyl oxime, caprolactam, phenol, and catechol; And / or, the diamine includes at least one of ethylenediamine, propylenediamine, cyclohexanediamine, diethyl toluene diamine, sodium ethylenediamine ethyl sulfonate, and sodium 2,4-diaminobenzenesulfonate.

3. The reactive emulsifier according to claim 1, wherein, Among the hydroxy compounds, The diol includes at least one of 3-methyl-1,5-pentanediol, neopentyl glycol, ethylene glycol, cyclohexanediol, methyl propanediol, 1,3-propanediol, 1,4-bis(hydroxymethyl)cyclohexane, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,2-propanediol, diethylene glycol, tetrahydrofuran diol, 1,6-hexanediol, trimethylpentanediol, butylethylpropanediol, dipropylene glycol, tripropylene glycol, and ethylhexanediol; And / or, the alkoxy alcohol includes at least one of polyethylene glycol and fatty alcohol polyoxyethylene ether; And / or, the hydroxy-terminated siloxane includes at least one of hydroxy silicone oil and hydroxy-terminated organosilicon resin.

4. The preparation method of the reactive emulsifier according to any one of claims 1 to 3, characterized in that, Including the following steps: React a hydrophilic diisocyanate containing a sulfonate group with a hydroxyacrylate, or react a hydrophilic diisocyanate containing a sulfonate group with a hydroxyacrylate and any one of a blocking agent, a hydroxy compound, and a diamine to obtain the reactive emulsifier.

5. Use of the reactive emulsifier according to any one of claims 1 to 3 in acrylic emulsion polymerization.

6. The application according to claim 5, wherein The preparation raw materials of the acrylic emulsion polymerization include a polymerization monomer and a reactive emulsifier; the polymerization monomer includes an acrylic monomer, or an acrylic monomer and other monomers containing double bonds; the acrylic monomer includes at least one of acrylic acid, methacrylic acid, an acrylic ester containing a double bond, a methacrylic ester containing a double bond, acrylonitrile, acrylamide, N-methylolacrylamide, and hydroxyacrylate; The other monomers containing double bonds include at least one of an unsaturated dibasic acid, styrene, and vinyl acetate; The unsaturated dibasic acid includes at least one of maleic acid, itaconic acid, 2-pentenedioic acid, and 2-hexenedioic acid.

7. The application according to claim 6, characterized in that, The mass of the reactive emulsifier is 0.1% - 3% of the mass of the polymerization monomer; And / or, the raw materials for preparing the acrylic emulsion polymerization further include a buffer, an initiator, a pH regulator, and water.

8. The application according to claim 7, wherein The preparation method of the acrylic emulsion polymerization comprises the following steps: S1: Mix the polymerization monomers, part of the reactive emulsifier, part of the buffer, part of the initiator, and part of the water, and stir and emulsify to obtain a pre-emulsion. S2: Mix the remaining reactive emulsifier, buffer, initiator, and water, heat to 75-80 °C, then add part of the pre-emulsion, and control the temperature at 80-85 °C for seed polymerization reaction; then add the remaining pre-emulsion, and continue the polymerization reaction at 80-85 °C; then cool down, add the pH regulator and mix to obtain an acrylic emulsion.

9. An acrylic emulsion, characterized in that, The acrylic emulsion is prepared from raw materials including the reactive emulsifier according to any one of claims 1 to 3.

10. The acrylic emulsion prepared by the application according to any one of claims 5 to 8, or the application of the acrylic emulsion according to claim 9 in the preparation of an aqueous acrylic product, characterized in that, The aqueous acrylic products include aqueous acrylic coatings, aqueous acrylic paper brighteners, aqueous acrylic fabric finishing agents, aqueous acrylic pressure-sensitive adhesives, aqueous acrylic leather treatment liquids, aqueous acrylic amino baking varnishes, or aqueous acrylic polyurethane baking varnishes.

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