An acrylic emulsion with a core-shell structure, its preparation method and application

Abstract

This invention provides an acrylic emulsion with a core-shell structure, its preparation method, and its application. The acrylic emulsion with a core-shell structure includes a core and a shell. The raw materials for preparing the shell include a first acrylate monomer, an olefinic unsaturated acid monomer, an anionic emulsifier, a free radical initiator, and a neutralizing agent. The raw materials for preparing the core include a second acrylate monomer, a catalyst, an oxidizing agent, and a reducing agent. Since no acrylamide monomers are added to the monomers used in preparing the acrylic emulsion, the resulting acrylic emulsion is non-neurotoxic and will not harm human health. Furthermore, the specific core-shell structure allows the acrylic emulsion to have a suitable viscosity after being mixed with inorganic powders such as cement, preventing rapid gelation and facilitating construction.

Description

Technical Field

[0001] This invention belongs to the field of acrylic acid technology, specifically relating to an acrylic emulsion with a core-shell structure, its preparation method, and its application. Background Technology

[0002] Polymer cement-based waterproof coatings are widely used in building construction, kitchen and bathroom waterproofing, and roof waterproofing. They consist of two components: acrylic emulsion (pure acrylic, styrene-acrylic, vinyl acetate-acrylic) and inorganic powder (cement, filler, sand, etc.). Because the inorganic powder contains metal ions such as calcium ions, which can easily damage the double-layer structure of the latex particles, previous polymer cement-based acrylic emulsions generally used nonionic emulsion systems and hydrophilic monomers such as acrylamide to help maintain stability after the emulsion and powder are mixed.

[0003] CN106045410A discloses a flexible waterproof material comprising a liquid component and a powder component. The liquid component includes acrylic emulsion, p-hydroxybenzoic acid, polyacrylamide, polyoxyethylene polyoxypropylene pentaerythritol ether, FEA expanding agent, sulfonated oil, and sodium fluoride, with the remainder being water. The powder component includes pozzolanic silicate cement, HJS-09 plastic powder, quartz sand, kaolin, fly ash, mica powder, and methylcellulose. This invention can be formulated as a two-component, tough, plastic-modified polymer cement-based waterproof slurry. After mixing the powder and liquid components, it is applied to form a tough, highly elastic waterproof membrane. This membrane exhibits good adhesion to concrete and cement mortar, bonding firmly to the substrate to achieve a waterproof effect. It also demonstrates excellent flexibility, resisting minor vibrations and a certain degree of displacement. However, the drawbacks of this method are also obvious. Excessive nonionic emulsifiers reduce the water resistance of the film after formation. Furthermore, the use of acrylamide monomers results in a waterproof material with neurotoxicity, producing degrading amines that are harmful to human health.

[0004] Therefore, it is desirable to develop an acrylic emulsion that is free of acrylamide monomers and has a stable ionic emulsion system to solve the above problems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an acrylic emulsion with a core-shell structure, its preparation method, and its application. The raw materials for preparing the acrylic emulsion do not contain acrylamide monomers, and are therefore non-toxic. Furthermore, a core-shell structure is formed through a special structural design, enabling the final acrylic emulsion with a core-shell structure to have good compatibility with inorganic powders such as cement. After mixing, it can still maintain an appropriate construction open period and does not gel rapidly.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides an acrylic emulsion having a core-shell structure, wherein the core-shell structure includes a core and a shell layer;

[0008] The raw materials for preparing the shell layer include the following components in parts by weight:

[0009]

[0010] The raw materials for preparing the core include the following components in parts by weight:

[0011]

[0012] The first acrylate monomer can be 22 parts by weight, 24 parts by weight, 26 parts by weight, 28 parts by weight, 30 parts by weight, 32 parts by weight, 34 parts by weight, 36 parts by weight, or 38 parts by weight, etc.

[0013] The olefinic unsaturated acid monomer can be 1 part by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, or 4.5 parts by weight, etc.

[0014] The anionic emulsifier can be 0.01 parts by weight, 0.02 parts by weight, 0.03 parts by weight, 0.05 parts by weight, 0.1 parts by weight, 0.2 parts by weight, 0.4 parts by weight, 0.6 parts by weight, or 0.8 parts by weight, etc.

[0015] The free radical initiator can be 0.01 parts by weight, 0.05 parts by weight, 0.1 parts by weight, 0.15 parts by weight, 0.2 parts by weight, 0.25 parts by weight, 0.3 parts by weight, 0.35 parts by weight, 0.4 parts by weight, or 0.45 parts by weight, etc.

[0016] The neutralizing agent can be 0.2 parts by weight, 0.4 parts by weight, 0.6 parts by weight, 0.8 parts by weight, 1 part by weight, 1.2 parts by weight, 1.4 parts by weight, 1.6 parts by weight, or 1.8 parts by weight, etc.

[0017] The second acrylate monomer can be 62 parts by weight, 64 parts by weight, 66 parts by weight, 68 parts by weight, 70 parts by weight, 72 parts by weight, 74 parts by weight, 76 parts by weight, or 78 parts by weight, etc.

[0018] The catalyst can be 0.0015 parts by weight, 0.002 parts by weight, 0.0025 parts by weight, 0.003 parts by weight, 0.0035 parts by weight, 0.004 parts by weight, or 0.0045 parts by weight, etc.

[0019] The oxidant can be 0.25 parts by weight, 0.3 parts by weight, 0.35 parts by weight, 0.4 parts by weight, or 0.45 parts by weight, etc.

[0020] The reducing agent can be 0.25 parts by weight, 0.3 parts by weight, 0.35 parts by weight, 0.4 parts by weight, or 0.45 parts by weight, etc.

[0021] Preferably, the first acrylate monomer and the second acrylate monomer each independently comprise alkyl acrylate and / or alkyl methacrylate.

[0022] Preferably, the number of carbon atoms in the carbon chains of the alkyl acrylate and alkyl methacrylate is independently 1 to 20, for example 2, 4, 6, 8, 10, 12, 14, 16 or 18, more preferably 1 to 13, and even more preferably 1 to 10.

[0023] Preferably, the alkyl acrylate comprises any one or a combination of at least two of methyl acrylate, ethyl acrylate, n-butyl acrylate, tert-butyl acrylate, isooctyl acrylate, n-propyl acrylate, cyclohexyl acrylate, or isobornyl acrylate.

[0024] Preferably, the alkyl methacrylate is any one or a combination of at least two of the following: methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, n-propyl methacrylate, cyclohexyl methacrylate, tridecyl methacrylate, or octadecyl methacrylate.

[0025] Preferably, both the first acrylate monomer and the second acrylate monomer comprise a combination of methyl methacrylate, butyl acrylate, butyl methacrylate and isooctyl acrylate.

[0026] Preferably, the olefinic unsaturated acid monomer includes any one or a combination of at least two of the following: acrylic acid, methacrylic acid, itaconic acid, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, styrene sulfonic acid, vinyl sulfonic acid, 2-(meth)acryloylamino-2-methylpropanesulfonic acid, styrene sulfonate, vinyl sulfonate, or 2-(meth)acryloylamino-2-methylpropanesulfonic acid.

[0027] Preferably, the anionic emulsifier is a conventional anionic emulsifier, such as Disponil FES32, purchased from BASF, which is fatty alcohol polyoxyethylene ether (4EO) ammonium sulfate with an active ingredient content of 32%.

[0028] Preferably, the free radical initiator includes a peroxide-based free radical initiator or a redox-based free radical initiator.

[0029] Preferably, the peroxide radical initiator includes any one or a combination of at least two of potassium persulfate, ammonium persulfate, or sodium persulfate.

[0030] Preferably, the redox free radical initiator includes an oxidizing component and a reducing component.

[0031] Preferably, the redox free radical initiator further includes a catalytic component.

[0032] Preferably, the oxidizing component includes any one or a combination of at least two of the following: tert-butyl peroxide, potassium permanganate, ammonium persulfate, or an alkali metal salt of persulfate.

[0033] Preferably, the reducing component includes any one or a combination of at least two of sodium formaldehyde sulfoxylate, ascorbic acid, isoascorbic acid, sodium sulfite, sodium bisulfite, sodium dithionite, formamidinium sulfinic acid, hydroxymethyl sulfonic acid, or acetone bisulfite.

[0034] Preferably, the catalytic component includes any one or a combination of at least two of ferrous sulfate, nickel sulfate, copper chloride, manganese acetate, or vanadium acetate.

[0035] Preferably, the neutralizing agent includes any one or a combination of at least two of organic amine neutralizing agents, inorganic ammonia neutralizing agents, or alkali metal hydroxide neutralizing agents.

[0036] Preferably, the raw materials for preparing the shell layer also include deionized water.

[0037] Preferably, the content of deionized water in the raw materials for preparing the shell layer is 60 to 70 parts by weight, such as 61 parts by weight, 62 parts by weight, 63 parts by weight, 64 parts by weight, 65 parts by weight, 66 parts by weight, 67 parts by weight, 68 parts by weight, or 69 parts by weight.

[0038] Preferably, the catalyst comprises a combination of ferrous sulfate heptahydrate and disodium ethylenediaminetetraacetate dihydrate.

[0039] Preferably, the oxidant comprises tert-butylhydrogen peroxide.

[0040] Preferably, the reducing agent comprises Brügmann FF6M.

[0041] Preferably, the raw materials for preparing the core also include aromatic olefinic unsaturated monomers.

[0042] Preferably, the content of aromatic olefinic unsaturated monomers in the raw materials for preparing the core is 0 to 20 parts by weight and not equal to 0, for example, 2 parts by weight, 4 parts by weight, 6 parts by weight, 8 parts by weight, 10 parts by weight, 12 parts by weight, 14 parts by weight, 16 parts by weight or 18 parts by weight, etc.

[0043] Preferably, the aromatic olefinic unsaturated monomer includes any one or a combination of at least two of styrene, vinyltoluene, α-methylstyrene, p-methylstyrene, α-butylstyrene, 4-n-butylstyrene, or divinylbenzene.

[0044] Preferably, the raw materials for preparing the core layer also include deionized water.

[0045] Preferably, the content of deionized water in the raw materials for preparing the core layer is 10 to 20 parts by weight, such as 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, or 19 parts by weight.

[0046] In a second aspect, the present invention provides a method for preparing an acrylic emulsion as described in the first aspect, the method comprising the following steps:

[0047] (1) Dissolve the anionic emulsifier in deionized water, add some free radical initiator, then add the first acrylate monomer, olefinic unsaturated acid monomer and the remaining free radical initiator to react, and finally add a neutralizer to adjust the pH value to obtain a shell emulsion.

[0048] (2) A portion of the second acrylate monomer, optionally a portion of the aromatic olefin unsaturated monomer, catalyst, a portion of the oxidant and a portion of the reducing agent are added to the shell emulsion obtained in step (1) for reaction, and then the remaining portion of the second acrylate monomer, optionally the remaining portion of the aromatic olefin unsaturated monomer, the remaining portion of the oxidant and the remaining portion of the reducing agent are added for reaction to obtain the acrylic emulsion.

[0049] Preferably, the addition method described in step (1) is dropwise addition.

[0050] Thirdly, the present invention provides a polymer cement-based waterproof coating, characterized in that the polymer cement-based waterproof coating comprises a liquid component and a powder component;

[0051] The liquid material includes the acrylic emulsion as described in the first aspect;

[0052] The powder includes cement and filler.

[0053] Preferably, the filler comprises quartz sand and / or heavy calcium carbonate.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] (1) The acrylic emulsion with a core-shell structure provided by the present invention includes a core and a shell. The raw materials for preparing the shell and the raw materials for preparing the core do not contain acrylamide monomers, thereby making the prepared acrylic emulsion non-neurotoxic and harmless to human health. It also forms an acrylic emulsion with a stable ionic emulsion system. At the same time, through a specially designed monomer swelling process, the obtained acrylic emulsion has a core-shell structure, which can maintain an appropriate construction open period after being mixed with inorganic powders such as cement, and does not gel rapidly, thus effectively improving the compatibility of cement.

[0056] (2) The polymer cement-based waterproof coating provided by the present invention includes the acrylic emulsion with a core-shell structure, which can significantly improve the compatibility with cement and extend the construction open period; specifically, the viscosity of the polymer cement-based waterproof coating is 78-92 KU after 60 min, 78-91 KU after 120 min, 79-91 KU after 180 min, and 80-92 KU after 240 min. Detailed Implementation

[0057] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0058] Example 1

[0059] An acrylic emulsion with a core-shell structure is prepared by the following steps:

[0060] (1) Add 1020g of deionized water and 14.45g of anionic emulsifier Disponil to a four-necked flask equipped with a stirrer, thermometer, feed port, reflux condenser and nitrogen purging. FES32 (BASF, fatty alcohol polyoxyethylene ether (4EO) ammonium sulfate, 32% active ingredient content) was heated to 85°C with stirring. 0.564g of ammonium persulfate dissolved in 14g of deionized water was quickly added. After 2 minutes, the first monomer mixture (composed of 148.36g butyl acrylate, 342.74g methyl methacrylate and 28g acrylic acid) was added dropwise, which was completed in 180 minutes. At the same time as the first monomer mixture was added, 1.16g of ammonium persulfate dissolved in 42g of deionized water was added dropwise, which was completed in 190 minutes. After the addition was completed, the monomer tank and the initiator tank were rinsed with 8g of deionized water and added to the flask. The mixture was kept warm for 60 minutes. While maintaining 85°C, 13g of ammonia water (concentration of 25%) dissolved in 40g of deionized water was added dropwise, which was completed in 30 minutes. The pH of the emulsion was adjusted to 8.0 to obtain the shell emulsion.

[0061] (2) Cool the shell emulsion obtained in step (1) to 50°C, add half of the second monomer mixture (composed of 232.84g butyl acrylate, 132.84g methyl methacrylate and 70g styrene), stir and emulsify for 20 min, add 0.02g ferrous sulfate heptahydrate and 0.02g disodium ethylenediaminetetraacetate dihydrate, add 0.8g tert-butyl hydrogen peroxide aqueous solution (70% active ingredient content) dissolved in 5g deionized water, add 1.2g Brügmann FF6M dissolved in 12g deionized water, and allow the reaction system to polymerize. Wait for the system to heat up. The mixture was heated to the maximum temperature and held for 20 minutes. Then, it was cooled to 50°C and the remaining second monomer mixture was added. The mixture was stirred and emulsified for 20 minutes. 0.8 g of tert-butyl hydrogen peroxide aqueous solution (70% active ingredient content) dissolved in 5 g of deionized water was added. 1.2 g of Brügmann FF6M dissolved in 12 g of deionized water was added to allow the reaction system to polymerize again. The system was heated to the maximum temperature and held for another 20 minutes. The temperature was then cooled to below 40°C and filtered through a 200-mesh filter cloth. The final product had a solid content of 44.8%, a pH of 7.41, and a Brügmann viscosity of 676 mPa·s.

[0062] Example 2

[0063] An acrylic emulsion with a core-shell structure is prepared by the following steps:

[0064] (1) Add 1020g of deionized water and 13.31g of anionic emulsifier Disponil to a four-necked flask equipped with a stirrer, thermometer, feed port, reflux condenser and nitrogen purging. In FES32, the temperature was raised to 85°C with stirring. 0.564g of ammonium persulfate dissolved in 14g of deionized water was quickly added. After 2 minutes, the first monomer mixture (composed of 190.2g butyl acrylate, 302.60g methyl methacrylate, and 24g acrylic acid) was added dropwise, which was completed in 180 minutes. At the same time as the first monomer mixture was added dropwise, 1.16g of ammonium persulfate dissolved in 42g of deionized water was added dropwise, which was completed in 190 minutes. After the addition was completed, the monomer tank and the initiator tank were rinsed with 8g of deionized water and added to the flask. The mixture was kept warm for 60 minutes. While maintaining 85°C, 12g of ammonia solution (25% concentration) dissolved in 40g of deionized water was added dropwise, which was completed in 30 minutes. The pH of the emulsion was adjusted to 7.5 to obtain the shell emulsion.

[0065] (2) Cool the shell emulsion obtained in step (1) to 50°C, add half of the second monomer mixture (composed of 232.84g butyl acrylate, 132.84g methyl methacrylate and 70g styrene), stir and emulsify for 20 minutes, add 0.02g ferrous sulfate heptahydrate and 0.02g disodium ethylenediaminetetraacetate dihydrate, add 0.8g tert-butyl hydrogen peroxide aqueous solution (70% active ingredient content) dissolved in 5g deionized water, add 1.2g Brügmann FF6M dissolved in 12g deionized water, and allow the reaction system to polymerize. When the system is heated to the maximum temperature, it is held for 20 minutes. When the temperature is lowered to 50°C, the remaining second monomer mixture is added, and the mixture is stirred and emulsified for 20 minutes. Then, 0.8 g of tert-butyl hydrogen peroxide aqueous solution (70% active ingredient content) dissolved in 5 g of deionized water is added, along with 1.2 g of Brügmann FF6M dissolved in 12 g of deionized water, to allow the reaction system to polymerize again. When the system is heated to the maximum temperature, it is held for another 20 minutes. When the temperature is lowered to below 40°C, the mixture is filtered through a 200-mesh filter cloth. The final product has a solid content of 44.65%, a pH of 7.57, and a Brügmann viscosity of 489 mPa·s.

[0066] Example 3

[0067] An acrylic emulsion with a core-shell structure is prepared by the following steps:

[0068] (1) Add 1020g of deionized water and 14g of anionic emulsifier Disponil FES32 to a four-necked flask equipped with a stirrer, thermometer, feed port, reflux condenser and nitrogen purging. Heat to 85°C with stirring. Quickly add 0.564g of ammonium persulfate dissolved in 14g of deionized water. After 2 minutes, start adding the first monomer mixture (composed of 211.5g of butyl acrylate, 280.5g of methyl methacrylate and 24g of acrylic acid) dropwise. The addition is completed in 180 minutes. At the same time as adding the first monomer mixture, add 1.16g of ammonium persulfate dissolved in 42g of deionized water dropwise. The addition is completed in 190 minutes. After the addition is completed, rinse the monomer tank and the initiator tank with 8g of deionized water and add them to the flask. Keep warm for 60 minutes. Maintain 85°C and add 12g of ammonia water (25% concentration) dissolved in 40g of deionized water dropwise. The addition is completed in 30 minutes. Adjust the pH of the emulsion to 7.5 to obtain the shell emulsion.

[0069] (2) Cool the shell emulsion obtained in step (1) to 50°C, add half of the second monomer mixture (composed of 234g butyl acrylate and 202.1g methyl methacrylate), stir and emulsify for 20 min, add 0.02g ferrous sulfate heptahydrate and 0.02g disodium ethylenediaminetetraacetate dihydrate, add 0.8g tert-butyl hydrogen peroxide aqueous solution (70% active ingredient content) dissolved in 5g deionized water, add 1.2g Brügmann FF6M dissolved in 12g deionized water, and allow the reaction system to polymerize. Wait for the system to heat up to the highest temperature. The mixture was kept at 20°C for 20 minutes, then cooled to 50°C. The remaining second monomer mixture was added, and the mixture was stirred and emulsified for 20 minutes. 0.8 g of tert-butyl hydrogen peroxide aqueous solution (70% active ingredient content) dissolved in 5 g of deionized water was added, along with 1.2 g of Brügmann FF6M dissolved in 12 g of deionized water. The reaction system was allowed to polymerize again. When the system reached its maximum temperature, it was kept at that temperature for another 20 minutes. The temperature was then lowered to below 40°C and filtered through a 200-mesh filter cloth. The final product had a solid content of 44.92%, a pH of 7.5, and a Brügmann viscosity of 510 mPa·s.

[0070] Example 4

[0071] An acrylic emulsion with a core-shell structure, which differs from Example 1 only in that styrene is not added to the second monomer mixture, while the other components, amounts and preparation methods are the same as in Example 1.

[0072] Example 5

[0073] An acrylic emulsion with a core-shell structure is prepared by the following steps:

[0074] (1) Add 1020g of deionized water and 14.45g of anionic emulsifier Disponil to a four-necked flask equipped with a stirrer, thermometer, feed port, reflux condenser and nitrogen purging. FES32 was heated to 85°C with stirring. 0.564g of ammonium persulfate dissolved in 14g of deionized water was quickly added. After 2 minutes, the first monomer mixture (composed of 148.36g of butyl acrylate, 342.74g of methyl methacrylate, and 28g of acrylic acid) was added dropwise, which was completed in 180 minutes. At the same time as the first monomer mixture was added, 1.16g of ammonium persulfate dissolved in 42g of deionized water was added dropwise, which was completed in 190 minutes. After the addition was completed, the monomer tank and the initiator tank were rinsed with 8g of deionized water and added to the flask. The mixture was kept at 85°C for 60 minutes. 13g of ammonia solution (25% concentration) dissolved in 40g of deionized water was added dropwise, which was completed in 30 minutes. The pH of the emulsion was adjusted to 8.0 to obtain the shell emulsion.

[0075] (2) Cool the shell emulsion obtained in step (1) to 50°C, add the second monomer mixture (composed of 232.84g butyl acrylate, 132.84g methyl methacrylate and 70g styrene), stir and emulsify for 20min, add 0.02g ferrous sulfate heptahydrate and 0.02g disodium ethylenediaminetetraacetate dihydrate, add 1.6g tert-butyl hydrogen peroxide aqueous solution (70% active ingredient content) dissolved in 10g deionized water, add 2.4g Brügmann FF6M dissolved in 24g deionized water, and polymerize the reaction system. When the system reaches the highest temperature, continue to keep it warm for 20min, cool it to below 40°C, filter it through a 200-mesh filter cloth, and the final product has a solid content of 45.1%, a pH of 7.6, and a Brügmann viscosity of 330mPa·s.

[0076] Comparative Example 1

[0077] An acrylic emulsion, the preparation method of which includes the following steps:

[0078] (1) Add 670g of deionized water and 6g of Disponil FES32 to a four-necked flask equipped with a stirrer, thermometer, feed port, reflux condenser, and nitrogen purging. Heat to 85°C with stirring, and quickly add 0.564g of ammonium persulfate dissolved in 10g of deionized water. After 2 minutes, begin dropwise addition of the first monomer mixture (composed of 445.5g butyl acrylate, 482.6g methyl methacrylate, 24g acrylic acid, and 13.4g Disponil). The mixture consisted of FES32 and 394.5g of deionized water. The addition was completed over 180 minutes. Simultaneously, 2.85g of ammonium persulfate dissolved in 60g of deionized water was added dropwise, completing the addition over 190 minutes. After the addition was complete, the monomer tank and initiator tank were rinsed with 8g of deionized water and added to the flask. The mixture was kept at this temperature for 60 minutes, then cooled to 65°C. A single addition of 0.7g of tert-butyl hydrogen peroxide aqueous solution (70% active ingredient content) dissolved in 5g of deionized water and 0.5g of Brügmann FF6M dissolved in 5g of deionized water were added. The mixture was kept at this temperature for 30 minutes. The temperature was then lowered to below 40°C, and the pH was adjusted to greater than 7.0 with 25% ammonia. The mixture was filtered through a 200-mesh filter cloth. The final product had a solid content of 44.37%, a pH of 7.25, and a Brügmann viscosity of 260 mPa·s.

[0079] Comparative Example 2

[0080] An acrylic emulsion differs from Example 1 only in that acrylic acid is not added to the first monomer mixture, while the other components, amounts, and preparation methods are the same as in Example 1.

[0081] Application Example 1

[0082] A polymer cement-based waterproof coating comprising a liquid and a powder in a 1:1 mass ratio;

[0083] The preparation method of the liquid material includes: mixing 500g of acrylic emulsion with a core-shell structure (Example 1), 40g of alcohol ester twelve, 1g of surfactant Tergitol 15-S-40, 2g of defoamer BYK 022 and 1g of thickener TT-935 (Dow) to obtain the liquid material;

[0084] The preparation method of the powder includes: mixing 50g of PO42.5 cement, 25g of quartz sand and 25g of heavy calcium carbonate to obtain the powder;

[0085] The preparation method of the polymer cement-based waterproof coating includes: mixing liquid and powder to obtain the polymer cement-based waterproof coating.

[0086] Application Examples 2-5

[0087] A polymer cement-based waterproof coating differs from Application Example 1 only in that the core-shell structured acrylic emulsions obtained in Examples 2-5 are used instead of the core-shell structured acrylic emulsions obtained in Example 1. All other components, dosages, and preparation methods are the same as in Example 1.

[0088] Comparative application examples 1-2

[0089] A polymer cement-based waterproof coating differs from Application Example 1 only in that the acrylic emulsion with a core-shell structure obtained in Comparative Examples 1 and 2 is used instead of the acrylic emulsion with a core-shell structure obtained in Example 1. All other components, dosages, and preparation methods are the same as in Example 1.

[0090] Performance testing:

[0091] (1) Compatibility with cement: The compatibility between the emulsion and cement was characterized by monitoring the change in KU viscosity of the polymer cement-based waterproof coating at different standing times at room temperature (25℃).

[0092] The polymer cement-based waterproof coatings provided in Test Cases 1-5 and Comparative Application Examples 1-2 were tested according to the above test methods. The test results are shown in Table 1.

[0093] Table 1

[0094]

[0095]

[0096] According to the data in Table 1, the viscosity of the polymer cement-based waterproof coatings provided in Examples 1 to 5 is 78–92 KU after 60 minutes, 78–91 KU after 120 minutes, 79–91 KU after 180 minutes, and 80–92 KU after 240 minutes.

[0097] Comparing Application Example 1 and Comparative Application Example 1, it can be seen that, compared with the acrylic emulsion obtained by homogeneous emulsion polymerization provided in Comparative Example 1, the acrylic emulsion with a core-shell structure provided in Example 1 can significantly improve the compatibility with cement and extend the construction open period of the polymer cement-based waterproof coating.

[0098] Comparing Application Example 1 and Comparative Application Example 2, it can be seen that the polymer cement-based waterproof coating provided in Comparative Application Example 2 has already cured after 60 minutes, making it difficult to apply normally.

[0099] Further comparison of Application Example 1 and Application Examples 4-5 also shows that the absence of styrene in the second monomer mixture and the failure to add the second monomer in stages will affect the compatibility of the final acrylic emulsion with cement.

[0100] The applicant declares that this invention illustrates an acrylic emulsion with a core-shell structure, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this invention.

Claims

1. An acrylic emulsion having a core-shell structure, characterized by, The acrylic emulsion with a core-shell structure comprises a core and a shell layer. The raw materials for preparing the shell layer comprise the following components by weight: a first acrylic ester monomer 20-40 parts by weight an ethylenically unsaturated acid monomer 0.5-5 parts by weight an anionic emulsifier 0.05-1 part by weight a free radical initiator 0.05-0.5 part by weight a neutralizing agent 0.1-2 parts by weight; The raw materials for preparing the core comprise the following components by weight: a second acrylic ester monomer 60-80 parts by weight a catalyst 0.001-0.005 parts by weight an oxidizing agent 0.2-0.5 parts by weight a reducing agent 0.2-0.5 parts by weight. The acrylic emulsion is prepared by the following method: (1) Dissolve the anionic emulsifier in deionized water, add part of the free radical initiator, then add the first acrylic ester monomer, the ethylenically unsaturated acid monomer and the remaining part of the free radical initiator for reaction, and finally add the neutralizing agent to adjust the pH value to obtain the shell layer emulsion; (2) Add part of the second acrylic ester monomer, optionally part of the aromatic ethylenically unsaturated monomer, the catalyst, part of the oxidizing agent and part of the reducing agent to the shell layer emulsion obtained in step (1) for reaction, then add the remaining part of the second acrylic ester monomer, optionally the remaining part of the aromatic ethylenically unsaturated monomer, the remaining part of the oxidizing agent and the remaining part of the reducing agent for reaction to obtain the acrylic emulsion.

2. The acrylic emulsion according to claim 1, characterized in that, The first and second acrylic ester monomers each independently comprise an alkyl acrylate and / or an alkyl methacrylate.

3. The acrylic emulsion according to claim 2, characterized in that, The number of carbon atoms in the alkyl acrylate and alkyl methacrylate is independently 1-20.

4. The acrylic emulsion according to claim 3, characterized in that, The number of carbon atoms in the alkyl acrylate and alkyl methacrylate is independently 1-13.

5. The acrylic emulsion according to claim 4, characterized in that, The number of carbon atoms in the alkyl acrylate and alkyl methacrylate is independently 1-10.

6. The acrylic emulsion according to claim 2, characterized in that, The alkyl acrylate comprises any one or a combination of at least two of methyl acrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate, iso-octyl acrylate, n-propyl acrylate, cyclohexyl acrylate or isobornyl acrylate.

7. The acrylic emulsion according to claim 2, characterized in that, The alkyl methacrylate comprises any one or a combination of at least two of methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, n-propyl methacrylate, cyclohexyl methacrylate, tridecyl methacrylate or octadecyl methacrylate.

8. The acrylic emulsion of claim 1, wherein, The first and second acrylic ester monomers each independently comprise a combination of methyl methacrylate, butyl acrylate, butyl methacrylate and iso-octyl acrylate.

9. The acrylic emulsion of claim 1, wherein, The ethylenically unsaturated acid monomer comprises any one or a combination of at least two of acrylic acid, methacrylic acid, itaconic acid, sulfoethyl acrylate, sulfoethyl methacrylate, sulfopropyl acrylate, sulfopropyl methacrylate, styrene sulfonic acid, vinyl sulfonic acid, 2-(meth)acrylamido-2-methylpropane sulfonic acid, styrene sulfonate, vinyl sulfonate or 2-(meth)acrylamido-2-methylpropane sulfonate.

10. The acrylic emulsion of claim 1, wherein, The free radical initiator comprises a peroxide free radical initiator or a redox free radical initiator.

11. The acrylic emulsion according to claim 10, characterized in that, The peroxide free radical initiator comprises any one or a combination of at least two of potassium persulfate, ammonium persulfate or sodium persulfate.

12. The acrylic emulsion of claim 10, wherein, The redox free radical initiator comprises an oxidizing component and a reducing component.

13. The acrylic emulsion according to claim 12, characterized in that, The oxidizing component comprises any one or a combination of at least two of t-butyl peroxide, potassium permanganate, ammonium peroxodisulfate or alkali metal peroxodisulfate.

14. The acrylic emulsion of claim 12, wherein, The reducing component comprises any one or a combination of at least two of sodium formaldehyde sulfoxylate, ascorbic acid, erythorbic acid, sodium sulfite, sodium bisulfite, sodium dithionite, formamidine sulfinic acid, methylsulfonic acid or acetone bisulfite.

15. The acrylic emulsion of claim 10, wherein, The redox free radical initiator further comprises a catalytic component.

16. The acrylic emulsion according to claim 15, characterized in that, The catalytic component comprises any one or a combination of at least two of ferrous sulfate, nickel sulfate, copper chloride, manganese acetate or vanadium acetate.

17. The acrylic emulsion of claim 1, wherein, The neutralizing agent comprises any one or a combination of at least two of an organic amine neutralizing agent, an inorganic ammonia neutralizing agent or an alkali metal hydroxide neutralizing agent.

18. The acrylic emulsion of claim 1, wherein, The preparation raw material of the shell layer further comprises deionized water.

19. The acrylic emulsion according to claim 18, characterized in that, The content of the deionized water in the preparation raw material of the shell layer is 60-70 parts by weight.

20. The acrylic emulsion of claim 1, wherein, The catalyst comprises a combination of ferrous sulfate heptahydrate and disodium ethylenediaminetetraacetate dihydrate.

21. The acrylic emulsion of claim 1, wherein, The oxidizing agent comprises t-butyl hydroperoxide.

22. The acrylic emulsion of claim 1, wherein, The preparation raw material of the core further comprises an aromatic ethylenically unsaturated monomer.

23. The acrylic emulsion of claim 22, wherein, The content of the aromatic ethylenically unsaturated monomer in the preparation raw material of the core is 0-20 parts by weight and not equal to 0.

24. The acrylic emulsion of claim 22, wherein, The aromatic ethylenically unsaturated monomer comprises any one or a combination of at least two of styrene, vinyl toluene, α-methyl styrene, p-methyl styrene, α-butyl styrene, 4-n-butyl styrene or divinyl benzene.

25. The acrylic emulsion of claim 1, wherein, The preparation raw material of the core further comprises deionized water.

26. The acrylic emulsion of claim 25, wherein, The content of the deionized water in the preparation raw material of the core is 10-20 parts by weight.

27. A process for the preparation of an acrylic emulsion as claimed in any one of claims 1 to 26, characterised in that, The preparation method comprises the following steps: (1) dissolving an anionic emulsifier in deionized water, adding part of a free radical initiator, then adding a first acrylic ester monomer, an ethylenically unsaturated acid monomer and the remaining part of the free radical initiator to react, and finally adding a neutralizing agent to adjust the pH value to obtain a shell emulsion; (2) adding part of a second acrylic ester monomer, optionally part of an aromatic ethylenically unsaturated monomer, a catalyst, part of an oxidizing agent and part of a reducing agent to the shell emulsion obtained in step (1) to react, then adding the remaining part of the second acrylic ester monomer, optionally the remaining part of the aromatic ethylenically unsaturated monomer, the remaining part of the oxidizing agent and the remaining part of the reducing agent to react to obtain the acrylic emulsion.

28. A polymer cementitious based waterproofing coating, characterized in that, The polymer cement-based waterproof coating comprises a liquid material and a powder material. The liquid material comprises the acrylic emulsion according to any one of claims 1-26. The powder material comprises cement and a filler.

29. The polymer cementitious waterproofing coating of claim 28, wherein, The filler comprises quartz sand and / or heavy calcium carbonate.

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