Emulsion polymer with low coagulum amount, and method of making and use thereof

Abstract

The application discloses a low coagulum amount emulsion polymer, which comprises a cashew phenol structure unit-containing emulsifier and a highly hydrophobic monomer. The application polymerizes the highly hydrophobic monomer by using the cashew phenol emulsifier, and can effectively reduce the coagulum amount of the emulsion. The emulsion polymer prepared by using the application has the characteristics of hydrophobicity, good wetting property, self-crosslinking, plasticizing and the like. The water-based dispersion prepared by using the emulsifier can be applied to the fields of building, waterproofing, industry, textile coating or adhesive and the like.

Description

[0001] This application is a divisional application of application number 202210451878.1, filed on April 26, 2022, entitled "An Emulsion Polymer with Low Coagulation Content and Its Preparation Method and Application". Technical Field

[0002] This invention relates to an emulsion polymer with low coagulation content, its preparation method and application, belonging to the field of emulsion polymerization. Background Technology

[0003] Emulsion polymerization relies on the diffusion of monomers from monomer droplets into micelles via the aqueous phase. Highly hydrophobic monomers have very low solubility in the aqueous phase, hindering their efficient entry into the micelles for copolymerization. This often results in high coagulant content during polymerization, which can halt the process and negatively impact the final use of the material. While microemulsion or fine emulsion polymerization can address this issue, it also introduces new challenges, such as the need for co-emulsifiers and very high overall surfactant dosages. Therefore, new emulsion polymerization solutions specifically for highly hydrophobic monomers are required.

[0004] Patents US10538634B2 and WO2019161020A9 achieve emulsion polymerization of highly hydrophobic monomers by using carrier resins or solid-grade oligomers as emulsifiers. However, the resins used have high acid values, and to effectively reduce coagulation caused by highly hydrophobic monomers, the amount of carrier resin or solid-grade oligomers used is much higher than the amount of emulsifier used in conventional emulsion polymerization. The cyclodextrin pathway reported in patent CN1156727 requires a large amount of cyclodextrin; specifically, when octadecyl acrylate accounts for 30% of the total monomer weight, 6% cyclodextrin is needed. Patent US20210324114A1 reports the polymerization of a low-coagulation (filtered through a 100-mesh screen, <200 ppm) pure acrylic emulsion containing 20% ​​lauryl methacrylate as a monomer weight percentage, but the formulation contains a large amount of the highly hydrophilic monomer ethyl acrylate and the reactive stabilizing monomer sodium p-styrene sulfonate. Patent CN112300343A synthesized a pure acrylic emulsion containing high lauryl methacrylate or a branched acrylate with 17 carbon atoms (Evonik Terra C17.4-MA) through the synergistic effect of reactive anionic emulsifiers and reactive stable monomers, but the specific amount of coagulated material was not reported.

[0005] Cashews are the world's third-largest exported agricultural product, with annual production in major producing countries exceeding 2 million tons. Cashew nut oil is extracted from natural cashew shell oil, and its basic structure is shown below:

[0006]

[0007] R includes four structures:

[0008]

[0009] Cashew phenol, due to its unique structural characteristics, abundant resources, and low price, can be used as a modified amine curing agent, modified epoxy resin, unsaturated resin monomer / reactive diluent, and emulsifier, and has very important development and application value.

[0010] This invention uses an emulsifier containing cashew phenol structural units, which can effectively reduce the amount of coagulated material in the process of emulsion polymerization containing highly hydrophobic monomers, while giving the emulsion high crosslinking ability, high wetting ability and excellent plasticity. Summary of the Invention

[0011] The present invention provides an emulsion polymer with low coagulation content, comprising an emulsifier containing cashew phenol structural units and a highly hydrophobic monomer.

[0012] Preferably, the R group in the cashew phenol structural unit includes one or more of the four structures R1, R2, R3 and R4.

[0013] More preferably, the ratio of the four structures in the R group, R1:R2:R3:R4, is 3-5:30-35:20-25:40-45.

[0014]

[0015]

[0016] Preferably, the emulsifier containing cashew nut shell structural units includes one or more of anionic emulsifiers, nonionic emulsifiers, and anionic-nonionic emulsifiers containing cashew nut shell structural units.

[0017] More preferably, the emulsifier containing cashew nut shells is an anionic nonionic emulsifier; most preferably, the emulsifier containing cashew nut shells is cashew nut shell ethylene oxide sulfate and / or cashew nut shell ethylene oxide sulfosuccinate.

[0018] Preferably, the solid content of the emulsifier containing cashew phenol structural units accounts for 0.01%-10% of the solid content in the emulsion polymer, more preferably 0.1%-2%, and most preferably 0.2%-1%.

[0019] Preferably, the highly hydrophobic monomer is a substance containing double or triple bonds with a solubility of <0.005g in 100g water at 20°C, including C12-C18 alkyl esters of (meth)acrylic acid, cashew ether of (meth)acrylic acid, allyl glycidyl ether cashew ether, glycidyl methacrylate cashew ether, hydroxyethyl methacrylate cashew ether, ethylene tert-carbonate (such as VeoVaTM 10), and resin hybrid oligomers containing double or triple bonds (such as epoxy resin modified acrylate, alkyd resin modified acrylate); more preferably, the highly hydrophobic monomer is a C12-C18 alkyl ester of (meth)acrylic acid; most preferably, the highly hydrophobic monomer is lauryl methacrylate (LMA), such as Terra C13-MA, BASF LMA 1214F, and / or heptadecanyl methacrylate, such as Terra C17.4-MA.

[0020] Preferably, the highly hydrophobic monomer accounts for 3%-70% of the solid weight of the emulsion polymer, more preferably 3%-50%, and most preferably 5%-40%.

[0021] Preferably, the emulsion polymer, in addition to the emulsifier containing the cashew phenol structural unit and the highly hydrophobic monomer, also contains one or more of hard monomers, soft monomers and special functional monomers.

[0022] Preferably, the hard monomer is a monomer with a glass transition temperature ≥20°C, including one or more of styrene, methyl methacrylate, and vinyl acetate.

[0023] Preferably, the soft monomer is a monomer with a glass transition temperature of <20°C, including one or more of butyl acrylate and isooctyl acrylate.

[0024] Preferably, the special functional monomer includes one or more of the following: acrylic acid, methacrylic acid, itaconic acid, β-acryloyloxypropionic acid, maleic anhydride, fumaric acid, (meth)acrylamide, hydroxymethylacrylamide, acrylonitrile, hydroxyethyl (meth)acrylate, and hydroxypropyl (meth)acrylate.

[0025] Preferably, the special functional monomer further includes a crosslinking monomer; the crosslinking monomer includes, but is not limited to, one or more of vinyltrimethoxysilane (A-171), γ-methacryloyloxypropyltrimethoxysilane (A-174), Momentive silane coupling agent Coatosil MP200, trimethylolpropane triacrylate (TMPTA), and 1,6-hexanediol diacrylate (HDDA).

[0026] This invention also provides a method for preparing an emulsion polymer with low coagulation content, the specific steps of which include:

[0027] S1. Preparation of pre-emulsion: Add an emulsifier containing cashew phenol structural units to deionized water, stir evenly, and then add hard monomer, soft monomer, special functional monomer and highly hydrophobic monomer in sequence. Stir at 200-300 rpm for 30-60 minutes.

[0028] S2. Preparation of materials at the bottom of the vessel: Add one or more of cyclodextrin, sodium bicarbonate and emulsifier containing cashew phenol structural units to deionized water, heat to 90℃-92℃, and stir for 30 minutes.

[0029] S3. Polymerization process: Add the self-made seed emulsion to the bottom of the reactor, add some initiator, and then simultaneously add the pre-emulsion prepared in step S1 and the remaining initiator. The addition is completed in 4 hours, and the temperature is controlled at 90℃-92℃ during the addition process.

[0030] S4. Insulation stage: After the dripping is completed, keep warm at 90℃-92℃ for 90 minutes;

[0031] S5. Residual monomer elimination: Under conditions of 70-80℃, oxidizing agent and reducing agent are added dropwise in stages to eliminate residual monomers in the emulsion prepared in step S4;

[0032] S6. Post-processing: Cool the emulsion to below 40℃, adjust the pH value of the emulsion to 7.0-9.0, and then add defoamers and other additives to prepare the emulsion polymer.

[0033] This invention also provides an application of an emulsion polymer with low coagulation content. Preferably, the emulsion polymer is prepared by blending it with other water-based resins to obtain an aqueous dispersion, which is widely used in construction, waterproofing, industry, textile coatings or adhesives and other fields.

[0034] This invention utilizes cashew nut shell emulsifiers to polymerize highly hydrophobic monomers, effectively reducing the amount of coagulated material in the emulsion. Furthermore, the methylene structure in cashew nut shells imparts high crosslinking properties to the emulsion, while the long-chain, plant-oil-like characteristics of cashew nut shells result in high wetting ability and excellent plasticizing properties. Therefore, the emulsion polymer prepared by this invention exhibits hydrophobicity, good wetting properties, self-crosslinking, and plasticizing characteristics. Detailed Implementation

[0035] The present invention will be further described in conjunction with the following embodiments, but the scope of protection of the present invention is not limited thereto.

[0036] Example 1

[0037] A method for preparing an emulsion polymer with low coagulation content, comprising the following steps:

[0038] S1. Preparation of pre-emulsion: The anionic emulsifier used is ethoxylated cashew nut sulfate with a solid content of 80%, and the nonionic emulsifier is fatty alcohol polyoxyethylene ether; 0.32 parts of anionic emulsifier and 0.21 parts of nonionic emulsifier are added sequentially to 10.7 parts of deionized water, stirred for 10 minutes, and then 15.4 parts of styrene, 20.8 parts of butyl acrylate, 1 part of acrylamide, 16 parts of lauryl methacrylate (LMA), and 0.06 parts of methacrylic acid are added sequentially, and stirred at 200-300 rpm for 30 minutes;

[0039] S2. Preparation of materials at the bottom of the vessel: Add 0.265 parts of cyclodextrin and 0.025 parts of sodium bicarbonate to 19 parts of deionized water, heat to 90℃-92℃, and stir for 30 minutes.

[0040] S3. Polymerization process: Add 1.4 parts of self-made seed emulsion with an average particle size of 89nm and a solid content of 42% to the bottom of the reactor, add 0.047 parts of sodium persulfate initiator (pre-dissolved in water), and simultaneously add the pre-emulsion prepared in step S1 and 0.14 parts of sodium persulfate initiator (pre-dissolved in water) dropwise. The addition is completed in 4 hours, and the temperature is controlled at 90℃-92℃ during the addition process.

[0041] S4. Insulation stage: After the dripping is completed, keep warm at 90℃-92℃ for 90 minutes;

[0042] S5. Residual Monomer Elimination: Under 75℃ conditions, 0.233 parts of 70% TBHP tert-butyl hydroperoxide, sodium metabisulfite aqueous solution (0.2 parts pre-dissolved in water to obtain a 5-10% aqueous solution), and sodium bisulfite aqueous solution (0.01 parts pre-dissolved in water to obtain a 5-10% aqueous solution) are added dropwise to eliminate residual monomers in the emulsion prepared in step S4.

[0043] S6. Post-addition: Cool to below 40℃, neutralize the emulsion with caustic soda to a pH of 7.0-9.0, add 0.05% of NXZ mineral oil defoamer and other additives to prepare the emulsion polymer.

[0044] Example 2

[0045] A method for preparing an emulsion polymer with low coagulation content, comprising the following steps:

[0046] S1. Preparation of pre-emulsion: The anionic emulsifier used is 0.73 parts of 35% solid content ethoxylated cashew phenol sulfosuccinate, which replaces the anionic emulsifier in Example 1 with an equal solid content. The type and amount of nonionic emulsifier are the same as in Example 1. The anionic emulsifier and nonionic emulsifier are added sequentially to 10.7 parts of deionized water and stirred for 10 minutes. Then, 15.4 parts of styrene, 20.8 parts of butyl acrylate, 1 part of acrylamide, 16 parts of lauryl methacrylate (LMA), and 0.06 parts of methacrylic acid are added sequentially and stirred at 200-300 rpm for 30 minutes.

[0047] S2. Preparation of materials at the bottom of the vessel: Add 0.265 parts of cyclodextrin, 0.025 parts of sodium bicarbonate and 0.14 parts of 35% solid content cashew phenol sulfosuccinate emulsifier to 19 parts of deionized water, heat to 90℃-92℃, and stir for 30 minutes.

[0048] The remaining steps are the same as in Example 1.

[0049] Example 3

[0050] A method for preparing an emulsion polymer with low coagulation content, comprising the following steps:

[0051] S1. Preparation of pre-emulsion: The types and amounts of emulsifiers used are exactly the same as in Example 1. Anionic and nonionic emulsifiers are added sequentially to 10.7 parts of deionized water, and the mixture is stirred for 10 minutes. Then, 15.4 parts of methyl methacrylate, 20.8 parts of butyl acrylate, 1 part of acrylamide, 16 parts of lauryl methacrylate (LMA), and 0.06 parts of methacrylic acid are added sequentially, and the mixture is stirred at 200-300 rpm for 30 minutes.

[0052] The remaining steps are the same as in Example 1.

[0053] Example 4

[0054] A method for preparing an emulsion polymer with low coagulation content, comprising the following steps:

[0055] S1. Preparation of pre-emulsion: The type and amount of emulsifier used are exactly the same as in Example 1; anionic emulsifier and nonionic emulsifier are added sequentially to 10.7 parts of deionized water and stirred for 10 minutes; 15.4 parts of methyl methacrylate, 20.8 parts of butyl acrylate, 1 part of acrylamide, 16 parts of heptadecanyl methacrylate (C17.4-MA), and 0.06 parts of methacrylic acid are premixed and heptadecanyl methacrylate is fully dissolved, and then gradually added to the above-dispersed emulsifier solution and stirred at 200-300 rpm for 30 minutes;

[0056] The remaining steps are the same as in Example 1.

[0057] Example 5

[0058] A method for preparing an emulsion polymer with low coagulation content, comprising the following steps:

[0059] S1. Preparation of pre-emulsion: The type and amount of anionic emulsifier used are the same as in Example 1. Anionic emulsifier is added to 10.7 parts of deionized water and stirred for 10 minutes. Then, 18 parts of methyl methacrylate, 18.2 parts of butyl acrylate, 1 part of acrylamide, 16 parts of LMA lauryl methacrylate, and 0.06 parts of acrylic acid are added in sequence and stirred at 200-300 rpm for 30 minutes.

[0060] S2. Preparation of materials at the bottom of the vessel: Add 0.025 parts of sodium bicarbonate to 19 parts of deionized water (do not add cyclodextrin), heat to 90℃-92℃, and stir for 30 minutes;

[0061] The remaining steps are the same as in Example 1.

[0062] Comparative Example 1

[0063] A method for preparing an emulsion polymer, comprising the following steps:

[0064] S1. Preparation of pre-emulsion: The anionic emulsifier used is a combination of fatty alcohol polyoxyethylene ether sulfate and alkyl diphenyl ether sulfonate, and the nonionic emulsifier is fatty alcohol polyoxyethylene ether. 0.86 parts of the above emulsifier are added sequentially to 10.7 parts of deionized water, where the proportions of the three emulsifiers are 0.17 parts, 0.47 parts, and 0.21 parts, respectively. The mixture is stirred for 10 minutes, and then 14 parts of styrene, 38.2 parts of butyl acrylate, 1 part of acrylamide, and 0.06 parts of methacrylic acid are added sequentially. The mixture is stirred at 200-300 rpm for 30 minutes.

[0065] S2. Preparation of materials at the bottom of the vessel: Add 0.265 parts of cyclodextrin and 0.025 parts of sodium bicarbonate to 19 parts of deionized water, heat to 90℃-92℃, and stir for 30 minutes.

[0066] S3. Polymerization process: Add 1.4 parts of self-made seed emulsion with an average particle size of 89nm and a solid content of 42% to the bottom of the reactor, add 0.047 parts of sodium persulfate initiator (pre-dissolved in water), and simultaneously add the pre-emulsion prepared in step a) and 0.14 parts of sodium persulfate initiator (pre-dissolved in water). The addition is completed in 4 hours, and the temperature is controlled at 90℃-92℃ during the addition process.

[0067] S4. Insulation stage: After the dripping is completed, keep warm at 90℃-92℃ for 90 minutes;

[0068] S5. Residual Monomer Elimination: Under 75℃ conditions, 0.233 parts of 70% TBHP tert-butyl hydrogen peroxide aqueous solution, sodium metabisulfite aqueous solution (0.2 parts of sodium metabisulfite pre-dissolved in water to prepare a 5-10% aqueous solution), and sodium bisulfite aqueous solution (0.01 parts of reducing agent sodium bisulfite pre-dissolved in water to prepare a 5-10% aqueous solution) are added dropwise to eliminate residual monomers in the emulsion prepared in step S4.

[0069] S6. Post-addition: Cool to below 40℃, neutralize the emulsion with caustic soda to a pH of 7.0-8.0, add defoamer and other additives to prepare the emulsion polymer.

[0070] Comparative Example 2

[0071] A method for preparing an emulsion polymer, comprising the following steps:

[0072] S1. Preparation of pre-emulsion: Add 0.86 parts of the same emulsifier as in Comparative Example 1 to 10.7 parts of deionized water, stir for 10 minutes, then add 15.4 parts of styrene, 20.8 parts of butyl acrylate, 1 part of acrylamide, 16 parts of dodecyl methacrylate (LMA), and 0.06 parts of methacrylic acid, and stir at 200-300 rpm for 30 minutes.

[0073] The remaining steps in this embodiment are the same as those in Comparative Example 1.

[0074] Implementation effect

[0075] Table 1. Amount of coagulated material from different emulsion polymers

[0076]

[0077] The emulsion polymer prepared in Comparative Example 1 had an average particle size of 379.5 nm, and the amount of condensate filtered through a 120-mesh filter cloth was 100 ppm.

[0078] Compared to Comparative Example 1, Comparative Example 2 introduced a certain amount of the long-chain hydrophobic monomer lauryl methacrylate (LMA), but kept the emulsifier composition, calculated glass transition temperature (Tg) of the monomer ratio, and the types and amounts of functional monomers unchanged. The average particle size of the prepared emulsion was 386.4 nm, but the amount of condensate filtered through a 120-mesh filter cloth increased to 1370 ppm, which was much higher than that of Comparative Example 1.

[0079] Compared with Comparative Example 2, Example 1 used ethoxylated cashew nut sulfate emulsifier and other solids to replace the anionic emulsifier. The average particle size of the prepared emulsion polymer was 338.4 nm, and the amount of condensate filtered by the 120 mesh filter cloth was significantly reduced from 1370 ppm in Comparative Example 2 to about 260 ppm.

[0080] Compared with Comparative Example 2, Example 2 used ethoxylated cashew phenol sulfosuccinate emulsifier and other solids to replace the anionic emulsifier, and added a small amount of such anionic emulsifier to the bottom of the vessel. The average particle size of the prepared emulsion polymer was 178.4 nm, and the amount of condensate filtered by 120 mesh filter cloth was reduced from 1370 ppm in Comparative Example 2 to 200 ppm.

[0081] The emulsion prepared in Example 3 has a particle size of 373.2 nm, and the amount of condensate filtered through a 120-mesh filter cloth is approximately 10 ppm.

[0082] Compared to lauryl methacrylate (LMA) used in Example 1, heptadecanyl methacrylate (C17.4-MA) used in Example 4 has a longer carbon chain and is more hydrophobic, thus making it easier to form precipitates in emulsion polymerization. However, in Example 4, even with 16 parts of heptadecanyl methacrylate (C17.4-MA), the amount of precipitates obtained by filtering the emulsion polymer through a 120-mesh filter cloth was only 610 ppm (emulsion particle size 339.7 nm).

[0083] The emulsion prepared in Example 5 has a particle size of 359.4 nm, and even without the addition of any cyclodextrin, the amount of condensate filtered through a 120-mesh filter cloth is only about 10 ppm.

Claims

1. A low-condensate emulsion polymer, formed by emulsion polymerization of highly hydrophobic monomers via a mixture of an emulsifier containing cashew nut shell structural units, deionized water, and an initiator. Its features are, The highly hydrophobic monomer is a substance containing double or triple bonds with a solubility of <0.005g in 100g water at 20℃, including any one or more of the following: C12-C18 alkyl esters of (meth)acrylic acid, cashew ether of (meth)acrylic acid, allyl glycidyl ether cashew ether, glycidyl methacrylate cashew ether, hydroxyethyl ester cashew ether of (meth)acrylic acid, ethylene tert-carbonate, and resin hybrid oligomers containing double or triple bonds. The emulsifier containing the cashew phenol structural unit is cashew phenol ethylene oxide sulfate and / or cashew phenol ethylene oxide sulfosuccinate.

2. The low-coagulation-content emulsion polymer as described in claim 1, characterized in that, The structural formula of cashew phenol is as follows: ； The R group in the cashew phenol structural unit includes one or more of the four structures: R1, R2, R3, and R4. The ratio of the four structures in the R group, R1:R2:R3:R4, is 3-5:30-35:20-25:40-45; the solid content of the emulsifier containing the cashew phenol structural unit accounts for 0.01%-10% of the solid content in the emulsion polymer.

3. The low-coagulation-content emulsion polymer as described in claim 1, characterized in that, The highly hydrophobic monomer accounts for 3%-70% of the solid content in the emulsion polymer.

4. The low-coagulation-content emulsion polymer as described in claim 3, characterized in that, The highly hydrophobic monomer is a C12-C18 alkyl ester of (meth)acrylic acid.

5. The low-coagulation-content emulsion polymer as described in claim 4, characterized in that, The highly hydrophobic monomer is lauryl methacrylate and / or heptadecanyl methacrylate.

6. The low-coagulation-content emulsion polymer as described in claim 1, characterized in that, The low-coagulation-content emulsion polymer also includes one or more of hard monomers, soft monomers, special functional monomers, and crosslinking monomers; The hard monomer is a monomer with a glass transition temperature ≥20℃, including one or more of styrene, methyl methacrylate, and vinyl acetate; The soft monomer is a monomer with a glass transition temperature of <20°C, including one or more of butyl acrylate and isooctyl acrylate; The special functional monomers include one or more of the following: acrylic acid, methacrylic acid, itaconic acid, β-acryloyloxypropionic acid, maleic anhydride, fumaric acid, (meth)acrylamide, hydroxymethylacrylamide, acrylonitrile, hydroxyethyl (meth)acrylate, and hydroxypropyl (meth)acrylate. The crosslinking monomers include one or more of vinyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, Momentive silane coupling agent Coatosil MP200, trimethylolpropane triacrylate, and 1,6-hexanediol diacrylate.

7. A method for preparing a low-coagulation-content emulsion polymer according to any one of claims 1-6, characterized in that, The specific steps include: S1. Preparation of pre-emulsion: Add an emulsifier containing cashew phenol structural units to deionized water, stir evenly, and then add hard monomer, soft monomer, special functional monomer and highly hydrophobic monomer in sequence. Stir at 200-300 rpm for 30-60 minutes. S2. Preparation of materials at the bottom of the vessel: Add one or more of cyclodextrin, sodium bicarbonate and emulsifier containing cashew phenol structural units to deionized water, heat to 90℃-92℃, and stir for 30 minutes. S3. Polymerization process: Add the self-made seed emulsion to the bottom of the reactor, add some initiator, and then simultaneously add the pre-emulsion prepared in step S1 and the remaining initiator. The addition is completed in 4 hours, and the temperature is controlled at 90℃-92℃ during the addition process. S4. Insulation stage: After the dripping is completed, keep warm at 90℃-92℃ for 90 minutes; S5. Residual monomer elimination: Under conditions of 70-80℃, oxidizing agent and reducing agent are added dropwise in stages to eliminate residual monomers in the emulsion prepared in step S4; S6. Post-addition: Cool to below 40℃, adjust the pH of the emulsion to 7.0-9.0, and then add defoamer to prepare the emulsion polymer.

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