Biomass cement-based waterproof emulsion, preparation method therefor and use thereof

Abstract

The present invention relates to a biomass cement-based waterproof emulsion, a preparation method therefor and a use thereof. The emulsion is an emulsion polymer formed by carrying out a polymerization reaction on monomers by means of a mixture containing an emulsifier, water and an initiator, wherein the monomers include a monomer containing a vinyl unsaturated group, and further include a bioderived long-chain alkyl ester and bioderived isobornyl (meth)acrylate; and the sum of the long-chain alkyl ester and the isobornyl (meth)acrylate accounts for 15-60% by weight of the solid content of the emulsion polymer. Compared with the prior art, the present invention has a high bio-based content, utilizes bioderived monomers that are readily available and low-cost, and can obtain an emulsion that has high stability and demonstrates excellent mechanical properties when used in a cement-based waterproof coating.

Description

Biomass cement-based waterproof emulsion and its preparation method and application

[0001] This application claims the benefit of Chinese patent application No. 2024102218298, filed on February 28, 2024. This application incorporates the entirety of the aforementioned Chinese patent application. Technical Field

[0002] The present invention relates to the field of waterproof materials, and in particular to a biomass cement-based waterproof emulsion and a preparation method and application thereof. Background Art

[0003] Cement-based waterproof coatings are two-component, water-based building waterproof coatings made from polymer emulsions such as acrylic esters and cement, along with other additives. The polymer emulsion loses water, forming a cohesive, continuous, elastic film. The cement absorbs the water in the formula and hardens, creating a strong, elastic waterproof layer that interpenetrates and firmly bonds with the hardened cement. This type of coating offers advantages such as ease of application, low overall cost, short construction time, and is non-toxic and environmentally friendly, making it an indispensable component in the building waterproofing field.

[0004] Polymer emulsions are key to cementitious waterproof coatings. They are produced by emulsion polymerization of monomers through a mixture containing an emulsifier, water, and an initiator. Green, renewable bio-based monomers are ideal raw materials, and a higher bio-based content is more environmentally friendly. For example, the USDA's "Bio-Preferred" program requires a minimum bio-based content of 20% for general interior wall adhesives.

[0005] There are some reports on bio-based emulsions in the prior art. For example, Dow Chemical disclosed a method for synthesizing bio-based emulsions in patent document US20210324114A1. It uses bio-based ethanol to prepare ethyl acrylate, and combines it with some bio-based lauryl acrylate to obtain the final emulsion. Guangdong Badfu New Materials Co., Ltd. used C13-C17 long-chain acrylate as the sole bio-based source in patent document CN112300343A, using a reactive emulsifier and combining it with a reactive stabilizing monomer to prepare a bio-based emulsion for interior walls. DSM of the Netherlands disclosed a series of emulsion synthesis methods based on itaconate bio-based monomers in a series of patent documents such as CN106939060B. Evonik of Germany reported in patent documents WO2021191348A1, etc., a method for the polymerization of C16 and longer-chain acrylates / methacrylates, using a composition of sodium di(2-ethylhexyl)sulfosuccinate and sodium 1,4-di(tridecyl)thiobutenedioate as an emulsifier, and a large amount of additional organic solvents needs to be added during the polymerization process.

[0006] Although the above methods have obtained some bio-based emulsions, there are still problems such as difficulty in polymerization (slagging or oil floating is easy when the content of long-chain monomers is high), high raw material costs (such as itaconate), and limited sources (such as bio-based ethyl acrylate). Moreover, the above bio-based emulsions are not specifically used for cement-based waterproof coatings. Further research is still needed to improve the performance of cement waterproof coatings with bio-based emulsions.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to provide a biomass cement-based waterproof emulsion and its preparation method and application in order to solve the above problems.

[0009] The purpose of the present invention is achieved through the following technical solutions:

[0010] A biomass cement-based waterproof emulsion is an emulsion polymer formed by polymerizing monomers through a mixture containing an emulsifier, water, and an initiator. The monomers include monomers containing vinyl unsaturated groups, long-chain alkyl esters of biological origin, and isobornyl (meth)acrylate of biological origin. The sum of the long-chain alkyl esters and isobornyl (meth)acrylate accounts for 15% to 60% by weight of the solid content of the emulsion polymer, preferably 20% to 40%, and more preferably 22% to 35%.

[0011] As a preferred technical solution of the present invention, the weight ratio of the long-chain alkyl ester to isobornyl (meth)acrylate is 4-6:8-12, preferably 5-6:9-11.

[0012] As a preferred technical solution of the present invention, the monomer containing an ethylenically unsaturated group is composed of a hard monomer and a soft monomer, and the weight ratio of the hard monomer to the soft monomer is 2-10:25-35, preferably 3-8:28-33;

[0013] Preferably, the hard monomer is a monomer having a glass transition temperature ≥ 20°C, including one or more of styrene, methacrylic acid, methyl methacrylate, and vinyl acetate;

[0014] Preferably, the soft monomer is a monomer with a glass transition temperature of less than 20° C., including one or more of butyl acrylate, butyl methacrylate, isooctyl acrylate, and ethyl acrylate.

[0015] As a preferred technical solution of the present invention, the long-chain alkyl ester is a C12-C18 alkyl ester monomer, including C12-C18 alkyl (meth)acrylate, cardanol (meth)acrylate, allyl glycidyl ether cardanol ether, glycidyl methacrylate cardanol ether, and hydroxyethyl (meth)acrylate cardanol ether;

[0016] Preferably, the long chain alkyl ester is lauryl methacrylate (LMA), such as Terra C13-MA, BASF LMA 1214F.

[0017] As a preferred technical solution of the present invention, the emulsifier accounts for 0.05%-10% of the total weight of the monomer, preferably 1%-8%, and more preferably 2%-5%;

[0018] The emulsifier is an anionic emulsifier and / or a nonionic emulsifier;

[0019] The anionic emulsifier includes one or two of fatty alcohol polyoxyethylene ether sulfate (such as sodium fatty alcohol polyoxyethylene ether sulfate, CAS No. 9004-82-4), alkyl diphenyl ether sulfonate (such as sodium dodecyl diphenyl ether disulfonate, CAS No. 28519-02-0), sodium lauryl sulfate (CAS No. 151-21-3), sodium dodecyl sulfonate (CAS No. 2386-53-0), sodium dodecylbenzenesulfonate (CAS No. 25155-30-0), and sodium dodecyl polyoxyethylene ether sulfate (CAS No. 9004-82-4);

[0020] The nonionic emulsifier includes alkyl polyoxyethylene ether and isomeric alcohol polyoxyethylene ether.

[0021] As a preferred technical solution of the present invention, the initiator is a persulfate or an azo initiator, and the initiator accounts for 0.05%-5% of the total weight of the monomer, preferably 0.1%-3%, and more preferably 0.3%-1%;

[0022] Examples of persulfates include potassium persulfate, sodium persulfate, and ammonium persulfate, with sodium persulfate being preferred. Examples of azo initiators include azobisisobutylamidine hydrochloride, azobisisopropylimidazoline hydrochloride, azobisisobutyronitrile, and azobisisoheptylonitrile. In a preferred embodiment, the initiator is a persulfate, for example, sodium persulfate is preferred.

[0023] The amount of water in the emulsion is added according to the solid content. The solid content of the biomass cement-based waterproof emulsion of the present invention is 50-60%;

[0024] The monomers further comprise functional monomers and / or cross-linking monomers, wherein the functional monomers and / or cross-linking monomers account for 0.1-5%, preferably 0.5-3%, of the total weight of the monomers;

[0025] The functional monomers include one or more of acrylic acid, methacrylic acid, itaconic acid, β-acryloxypropionic acid, maleic anhydride, fumaric acid, (meth)acrylamide, hydroxymethylacrylamide, acrylonitrile, hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate;

[0026] The crosslinking monomer includes one or more of vinyltrimethoxysilane (A-171), γ-methacryloxypropyltrimethoxysilane (A-174), Momentive silane coupling agent Coatosil MP200, trimethylolpropane triacrylate (TMPTA) and 1,6-hexanediol diacrylate (HDDA).

[0027] A method for preparing a biomass cement-based waterproof emulsion comprises the following steps:

[0028] (1) Preparation of pre-emulsion: Emulsifier a, all monomers and water are mixed and stirred to obtain a pre-emulsion;

[0029] (2) Preparation of the bottom material: Add water, emulsifier b and buffer stabilizer into the reactor and stir evenly to obtain the bottom material;

[0030] (3) Polymerization reaction: add seed emulsion and initiator a to the bottom of the kettle under stirring, then add pre-emulsion and initiator b dropwise at the same time within 2-6 hours, and control the temperature at 83-85°C;

[0031] (4) Post-treatment: After the addition is completed, keep the mixture at 83-85°C for 30-120 minutes, eliminate the residual monomers, and adjust the pH to obtain the product.

[0032] As a preferred technical solution of the present invention, the mass ratio of the emulsifier a in step (1) to the emulsifier b in step (2) is 30-70:1, the emulsifier a is preferably a mixture of an anionic emulsifier and a nonionic emulsifier, and the emulsifier b is an anionic emulsifier;

[0033] And / or, the mass ratio of the amount of water used in step (1) to the monomer is 1:4-6; the mass ratio of the amount of water used in step (2) to the monomer is 1:2-3;

[0034] The mass ratio of water to the monomer is 1:4-6; the mass ratio of water to the monomer in step (2) is 1:2-3;

[0035] And / or, the buffer stabilizer in step (2) includes one or more of cyclodextrin, sodium bicarbonate, ammonium bicarbonate, and sodium dihydrogen phosphate, preferably cyclodextrin, and the amount of the buffer stabilizer added accounts for 0.1-1% of the total mass of the monomer; preferably 0.4-0.8%;

[0036] And / or, the mass ratio of initiator a to initiator b in step (3) is 1:2-4;

[0037] And / or, the seed emulsion in step (3) is a seed emulsion having a particle size of 70-100 nm and a solid content of 35-45%, and the amount of the seed emulsion added accounts for 1-5% of the total mass of the monomer; preferably 2-3%;

[0038] And / or, step (4) eliminates the residual monomers by adding an oxidizing agent and a reducing agent, and adjusts the pH by adding a neutralizing agent;

[0039] The oxidant includes tert-butyl hydroperoxide and hydrogen peroxide. The amount of the oxidant added is 0.05 wt% to 2 wt% relative to the total weight of the monomer, preferably 0.1 wt% to 1 wt%, preferably, added in the form of an aqueous solution;

[0040] The reducing agent includes bleaching agent, sodium metabisulfite, FF6M, L-ascorbic acid, and sodium ascorbate. The amount of the reducing agent added is 0.01 wt% to 2 wt% relative to the total weight of the monomers, preferably 0.1 wt% to 1 wt%. Preferably, the reducing agent is added in the form of an aqueous solution.

[0041] The neutralizing agent includes ammonia water, triethylamine, dimethylethanolamine, and 2-amino-2-methylpropanol.

[0042] As a preferred technical solution of the present invention, the seed emulsion in step (3) is prepared by the following method:

[0043] (1-1) uniformly mixing water, an emulsifier, a mixed monomer, and an initiator to prepare a pre-emulsion of the seed emulsion;

[0044] (1-2) Add water and emulsifier to the reactor, mix well, heat to 75-85°C, and add initiator;

[0045] (1-3) adding 1 wt% to 5 wt% of the pre-emulsion of the seed emulsion in step (1-1) into a reaction kettle, and after the temperature rises to 75-85° C., uniformly adding the remaining pre-emulsion of the seed emulsion dropwise for a total of 2-4 hours. After the addition is complete, cooling to room temperature to obtain a seed emulsion;

[0046] The mixed monomer consists of the following components in parts by weight: 17-19 parts of butyl acrylate, 17-19 parts of methyl methacrylate, and 0.7-0.9 parts of methacrylic acid.

[0047] And / or, in step (1-1), the amount of the emulsifier is 1-15wt%, preferably 5-10wt%, of the total weight of the mixed monomers; the amount of the water is 70-85wt%, preferably 75-85wt% of the total weight of the mixed monomers; the amount of the initiator is 0.1-2wt%, preferably 0.5-1wt% of the total weight of the mixed monomers;

[0048] And / or, the amount of the emulsifier in step (1-2) accounts for 2-10wt% of the total weight of the mixed monomers, preferably 6-8wt%; the amount of water accounts for 50-70wt% of the total weight of the mixed monomers, preferably 50-60wt%; the amount of the initiator accounts for 0.1-1.5wt% of the total weight of the mixed monomers, preferably 0.6-1.2wt%.

[0049] A cement-based waterproof coating, the raw materials for its preparation include the waterproof emulsion described above.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] The raw materials for preparing the acrylic ester emulsion of the present invention are high-content C12-C17 alkyl (meth)acrylates and isobornyl (meth)acrylates. Both raw materials have a wide range of biological sources, are relatively easy to obtain, and have low costs, ensuring that the bio-based content of the emulsion remains at a high level. At the same time, by matching long-chain alkyl esters and isobornyl (meth)acrylates in a suitable ratio, the problem of slagging or oil floating during polymerization when the content of long-chain monomers is high can be avoided, and these two bio-based monomers have strong hydrophobic properties, and the water absorption rate of the waterproof coating prepared is much lower than that of other waterproof coatings. In addition, a small amount of seed emulsion of a specific particle size is added to the bottom material of the kettle during emulsion polymerization, which greatly improves the batch stability of the final particle size of the emulsion and improves the stability of the emulsion. The acrylic ester emulsion of the present invention has excellent performance when used in cement-based waterproof emulsions, and experimental results show that the tensile strength and elongation of the paint film are excellent. DETAILED DESCRIPTION

[0052] The present invention will be described in detail below with reference to specific embodiments, but the present invention is by no means limited thereto.

[0053] The seed emulsion used below was prepared by the following method:

[0054] Prepare a pre-emulsion by uniformly mixing 25 parts of deionized water, 2 parts of sodium lauryl sulfate, 34.8 parts of a mixed monomer (17 parts of butyl acrylate, 17 parts of methyl methacrylate, and 0.8 parts of methacrylic acid), and an initiator (0.2 parts of ammonium persulfate dissolved in 2 parts of deionized water).

[0055] Prepare the bottom liquid: add 20 parts of deionized water and 2.4 parts of sodium lauryl sulfate to the reactor and mix well. Heat to 78°C and add the initiator (0.24 parts of ammonium persulfate dissolved in 2 parts of deionized water).

[0056] Polymerization reaction: About 4 wt% of the pre-emulsion was added to the reactor. After the temperature returned to 78°C, the remaining pre-emulsion was added dropwise at a uniform rate for 3 hours. After the addition was completed, the mixture was cooled to room temperature to obtain a seed emulsion. The particle size of the emulsion was tested using a Malvern particle size tester. The particle size of the seed emulsion was 89 nm and the solid content was 42%.

[0057] Example 1

[0058] (1) Preparation of pre-emulsion: Add emulsifier (0.168 parts of sodium fatty alcohol polyoxyethylene ether sulfate, 0.42 parts of sodium dodecyl diphenyl ether disulfonate, 0.1 parts of alkyl polyoxyethylene ether, 0.1 parts of isomeric alcohol polyoxyethylene ether) and 1 part of acrylamide to 10.7 parts of deionized water, stir for 10 minutes, then add 3.9 parts of styrene, 10.6 parts of isobornyl acrylate (CAS No. 5888-33-5), 32.3 parts of butyl acrylate, 0.06 parts of methacrylic acid, and 5.4 parts of lauryl methacrylate (CAS No. 142-90-5) in sequence, and stir at 200-300 rpm for 30 minutes;

[0059] (2) Preparation of the bottom material: 19 parts of deionized water were added to the reactor, heated to 83-85°C, and then 0.02 parts of sodium dodecyl diphenyl ether disulfonate and 0.27 parts of cyclodextrin were added and stirred for 30 minutes;

[0060] (3) Polymerization process: 1.4 parts of a seed emulsion with a particle size of 89 nm and a solid content of 42% was added to the bottom of the kettle under stirring, followed by 0.047 parts of a pre-dissolved sodium persulfate initiator (0.047 parts of sodium persulfate dissolved in 1.5 parts of deionized water), and then the pre-emulsion and 0.14 parts of a pre-dissolved sodium persulfate initiator solution (0.14 parts of sodium persulfate dissolved in 3 parts of deionized water) were added dropwise simultaneously over a period of 4 hours. The temperature during the addition process was controlled at 83-85°C.

[0061] (4) Insulation stage: After the addition is complete, insulate at 83-85°C for 90 minutes;

[0062] (5) Elimination of residual monomers: Cool the emulsion to 78°C and add 0.35 parts of 70% tert-butyl hydroperoxide (dissolved in 3.85 parts of deionized water) and 0.3 parts of sodium metabisulfite (dissolved in 4 parts of deionized water) dropwise in steps to eliminate the residual monomers in the emulsion;

[0063] (6) Post-addition: Cool the mixture to below 40°C and add caustic soda to neutralize the emulsion to a pH of 7.5 to obtain the product.

[0064] Example 2

[0065] (1) Preparation of pre-emulsion: Add emulsifier (0.168 parts of sodium fatty alcohol polyoxyethylene ether sulfate, 0.42 parts of sodium dodecyl diphenyl ether disulfonate, 0.1 parts of alkyl polyoxyethylene ether, 0.1 parts of isomeric alcohol polyoxyethylene ether) and 1 part of acrylamide to 10.7 parts of deionized water, stir for 10 minutes, then add 7.5 parts of styrene, 10.6 parts of isobornyl acrylate (CAS No. 5888-33-5), 28.7 parts of butyl acrylate, 0.06 parts of methacrylic acid, and 5.4 parts of lauryl methacrylate (CAS No. 142-90-5) in sequence, and stir at 200-300 rpm for 30 minutes;

[0066] (2) Preparation of the bottom material: 19 parts of deionized water were added to the reactor, heated to 83-85°C, and then 0.02 parts of sodium dodecyl diphenyl ether disulfonate and 0.27 parts of cyclodextrin were added and stirred for 30 minutes;

[0067] (3) Polymerization process: 1.4 parts of a seed emulsion with a particle size of 89 nm and a solid content of 42% was added to the bottom of the kettle under stirring, followed by 0.047 parts of a pre-dissolved sodium persulfate initiator (0.047 parts of sodium persulfate dissolved in 1.5 parts of deionized water), and then the pre-emulsion and 0.14 parts of a pre-dissolved sodium persulfate initiator solution (0.14 parts of sodium persulfate dissolved in 3 parts of deionized water) were added dropwise simultaneously. The addition was completed over 4 hours, and the temperature during the addition process was controlled at 83-85°C.

[0068] (4) Insulation stage: After the addition is complete, insulate at 83-85°C for 90 minutes;

[0069] (5) Elimination of residual monomers: Cool the emulsion to 78°C and add 0.35 parts of 70% tert-butyl hydroperoxide (dissolved in 3.85 parts of deionized water) and 0.3 parts of sodium metabisulfite (dissolved in 4 parts of deionized water) dropwise in steps to eliminate the residual monomers in the emulsion;

[0070] (6) Post-addition: Cool the mixture to below 40°C and add caustic soda to neutralize the emulsion to a pH of 7.5 to obtain the product.

[0071] Example 3

[0072] (1) Preparation of pre-emulsion: Add emulsifier (0.168 parts of sodium fatty alcohol polyoxyethylene ether sulfate, 0.42 parts of sodium dodecyl diphenyl ether disulfonate, 0.1 parts of alkyl polyoxyethylene ether, 0.1 parts of isomeric alcohol polyoxyethylene ether) and 1 part of acrylamide to 10.7 parts of deionized water, stir for 10 minutes, then add 3.9 parts of styrene, 10.6 parts of isobornyl acrylate (CAS No. 5888-33-5), 32.3 parts of butyl acrylate, and 5.4 parts of lauryl methacrylate (CAS No. 142-90-5) in sequence, and stir at 200-300 rpm for 30 minutes;

[0073] (2) Preparation of the bottom material: 19 parts of deionized water were added to the reactor, heated to 83-85°C, and then 0.02 parts of sodium dodecyl diphenyl ether disulfonate and 0.27 parts of cyclodextrin were added and stirred for 30 minutes;

[0074] (3) Polymerization process: 1.4 parts of a seed emulsion with a particle size of 89 nm and a solid content of 42% was added to the bottom of the kettle under stirring, followed by 0.047 parts of a pre-dissolved sodium persulfate initiator (0.047 parts of sodium persulfate dissolved in 1.5 parts of deionized water), and then the pre-emulsion and 0.14 parts of a pre-dissolved sodium persulfate initiator solution (0.14 parts of sodium persulfate dissolved in 3 parts of deionized water) were added dropwise simultaneously over a period of 4 hours. The temperature during the addition process was controlled at 83-85°C.

[0075] (4) Insulation stage: After the addition is complete, insulate at 83-85°C for 90 minutes;

[0076] (5) Elimination of residual monomers: Cool the emulsion to 78°C and add 0.35 parts of 70% tert-butyl hydroperoxide (dissolved in 3.85 parts of deionized water) and 0.3 parts of sodium metabisulfite (dissolved in 4 parts of deionized water) dropwise in steps to eliminate the residual monomers in the emulsion;

[0077] (6) Post-addition: Cool the mixture to below 40°C and add caustic soda to neutralize the emulsion to a pH of 7.5 to obtain the product.

[0078] Example 4

[0079] (1) Preparation of pre-emulsion: Add emulsifier (0.168 parts of sodium fatty alcohol polyoxyethylene ether sulfate, 0.42 parts of sodium dodecyl diphenyl ether disulfonate, 0.1 parts of alkyl polyoxyethylene ether, 0.1 parts of isomeric alcohol polyoxyethylene ether) and 1 part of acrylamide to 10.7 parts of deionized water, stir for 10 minutes, then add 7.5 parts of styrene, 10.6 parts of isobornyl acrylate (CAS No. 5888-33-5), 28.7 parts of butyl acrylate, and 5.4 parts of lauryl methacrylate (CAS No. 142-90-5) in sequence, and stir at 200-300 rpm for 30 minutes;

[0080] (2) Preparation of the bottom material: 19 parts of deionized water were added to the reactor, heated to 83-85°C, and then 0.02 parts of sodium dodecyl diphenyl ether disulfonate and 0.27 parts of cyclodextrin were added and stirred for 30 minutes;

[0081] (3) Polymerization process: 1.4 parts of a seed emulsion with a particle size of 89 nm and a solid content of 42% was added to the bottom of the kettle under stirring, followed by 0.047 parts of a pre-dissolved sodium persulfate initiator (0.047 parts of sodium persulfate dissolved in 1.5 parts of deionized water), and then the pre-emulsion and 0.14 parts of a pre-dissolved sodium persulfate initiator solution (0.14 parts of sodium persulfate dissolved in 3 parts of deionized water) were added dropwise simultaneously over a period of 4 hours. The temperature during the addition process was controlled at 83-85°C.

[0082] (4) Insulation stage: After the addition is complete, insulate at 83-85°C for 90 minutes;

[0083] (5) Elimination of residual monomers: Cool the emulsion to 78°C and add 0.35 parts of 70% tert-butyl hydroperoxide (dissolved in 3.85 parts of deionized water) and 0.3 parts of sodium metabisulfite (dissolved in 4 parts of deionized water) dropwise in steps to eliminate the residual monomers in the emulsion;

[0084] (6) Post-addition: Cool the mixture to below 40°C and add caustic soda to neutralize the emulsion to a pH of 7.5 to obtain the product.

[0085] Comparative Example 1

[0086] (1) Preparation of pre-emulsion: Add emulsifier (0.168 parts of sodium fatty alcohol polyoxyethylene ether sulfate, 0.42 parts of sodium dodecyl diphenyl ether disulfonate, 0.1 parts of alkyl polyoxyethylene ether, 0.1 parts of isomeric alcohol polyoxyethylene ether) and 1 part of acrylamide to 10.7 parts of deionized water, stir for 10 minutes, then add 7.5 parts of styrene, 28.7 parts of butyl acrylate, 0.06 parts of methacrylic acid, and 16 parts of lauryl methacrylate (CAS No. 142-90-5) in sequence, and stir at 200-300 rpm for 30 minutes;

[0087] (2) Preparation of the bottom material: 19 parts of deionized water were added to the reactor, heated to 83-85°C, and then 0.02 parts of sodium dodecyl diphenyl ether disulfonate and 0.27 parts of cyclodextrin were added and stirred for 30 minutes;

[0088] (3) Polymerization process: 1.4 parts of a seed emulsion with a particle size of 89 nm and a solid content of 42% was added to the bottom of the kettle under stirring, followed by 0.047 parts of a pre-dissolved sodium persulfate initiator (0.047 parts of sodium persulfate dissolved in 1.5 parts of deionized water), and then the pre-emulsion and 0.14 parts of a pre-dissolved sodium persulfate initiator solution (0.14 parts of sodium persulfate dissolved in 3 parts of deionized water) were added dropwise simultaneously over a period of 4 hours. The temperature during the addition process was controlled at 83-85°C.

[0089] (4) Insulation stage: After the addition is complete, insulate at 83-85°C for 90 minutes;

[0090] (5) Elimination of residual monomers: Cool the emulsion to 78°C and add 0.35 parts of 70% tert-butyl hydroperoxide (dissolved in 3.85 parts of deionized water) and 0.3 parts of sodium metabisulfite (dissolved in 4 parts of deionized water) dropwise in steps to eliminate the residual monomers in the emulsion;

[0091] (6) Post-addition: Cool the mixture to below 40°C and add caustic soda to neutralize the emulsion to a pH of 7.5 to obtain the product.

[0092] Comparative Example 2

[0093] (1) Preparation of pre-emulsion: Add emulsifier (0.168 parts of sodium fatty alcohol polyoxyethylene ether sulfate, 0.42 parts of sodium dodecyl diphenyl ether disulfonate, 0.1 parts of alkyl polyoxyethylene ether, 0.1 parts of isomeric alcohol polyoxyethylene ether) and 1 part of acrylamide to 10.7 parts of deionized water, stir for 10 minutes, then add 0.25 parts of styrene, 14 parts of isobornyl acrylate (CAS No. 5888-33-5), 36.9 parts of butyl acrylate, 0.06 parts of methacrylic acid, and 2 parts of lauryl methacrylate (CAS No. 142-90-5) in sequence, and stir at 200-300 rpm for 30 minutes;

[0094] (2) Preparation of the bottom material: 19 parts of deionized water were added to the reactor, heated to 83-85°C, and then 0.02 parts of sodium dodecyl diphenyl ether disulfonate and 0.1 parts of cyclodextrin were added and stirred for 30 minutes;

[0095] (3) Polymerization process: 1.4 parts of a seed emulsion with a particle size of 89 nm and a solid content of 42% was added to the bottom of the kettle under stirring, followed by 0.047 parts of a pre-dissolved sodium persulfate initiator (0.047 parts of sodium persulfate dissolved in 1.5 parts of deionized water), and then the pre-emulsion and 0.14 parts of a pre-dissolved sodium persulfate initiator solution (0.14 parts of sodium persulfate dissolved in 3 parts of deionized water) were added dropwise simultaneously over a period of 4 hours. The temperature during the addition process was controlled at 83-85°C.

[0096] (4) Insulation stage: After the addition is complete, insulate at 83-85°C for 90 minutes;

[0097] (5) Elimination of residual monomers: Cool the emulsion to 78°C and add 0.35 parts of 70% tert-butyl hydroperoxide (dissolved in 3.85 parts of deionized water) and 0.3 parts of sodium metabisulfite (dissolved in 4 parts of deionized water) dropwise in steps to eliminate the residual monomers in the emulsion;

[0098] (6) Post-addition: Cool the mixture to below 40°C and add caustic soda to neutralize the emulsion to a pH of 7.5 to obtain the product.

[0099] Comparative Example 3

[0100] Taking Example 2 as a reference, the seed emulsion was not added in step (3), and the rest were the same as in Example 2.

[0101]

Emulsion performance test

[0102] The above-mentioned acrylic emulsion was tested using the following method. The experimental results are shown in Table 1.

[0103] The solid content of the emulsion is tested according to 4.3 of GB / T 20623-2006.

[0104] The viscosity test was performed using a Brookfield LV at 25°C, 2#, and 60 rpm.

[0105] The particle size was tested using a Malvern particle size tester.

[0106] The slag discharge rate is calculated after filtering through a 100-mesh filter.

[0107] The residual quantity is determined according to Appendix A of GB / T 20623-2006.

[0108] Bio-based content is calculated as the percentage of bio-based monomers in the emulsion polymer solids.

[0109] Table 1 Emulsion performance test results

[0110] As can be seen from the results in Table 1, the present invention uses a long-chain alkyl ester and isobornyl (meth)acrylate compounded in a certain ratio, the amount of gel produced by polymerization is minimal, and the batch particle size obtained using the seed emulsion is consistent.

[0111] The emulsion obtained above was used to prepare a cement waterproof coating (liquid-to-powder weight ratio of 1:1.5) according to the formula shown in Table 2. The tensile strength / elongation of the paint film was tested according to GB / T23445-2009 standard (the standard requires tensile strength ≥1.8 MPa and elongation ≥80%). The experimental results are detailed in Table 3.

[0112] Table 2 Cement waterproof coating formula

[0113] Table 3 Mechanical properties test results

[0114] The results in Table 3 show that the mechanical properties of a coating prepared by polymerization of lauryl methacrylate and isobornyl acrylate in a specific ratio are superior to those obtained using isobornyl acrylate alone. This is likely due to the presence of a methyl group and a cyclic structure in isobornyl acrylate, resulting in a higher Tg than lauryl methacrylate and lower flexibility. Even increasing the amount of n-butyl acrylate does not reduce the strength improvement achieved by isobornyl acrylate, and its inherent flexibility is inferior to that of lauryl methacrylate.

[0115] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A biomass cement-based waterproof emulsion is an emulsion polymer formed by polymerizing monomers in a mixture containing an emulsifier, water and an initiator, characterized in that: The monomers include monomers containing vinyl unsaturated groups, and also include long-chain alkyl esters with biological sources and isobornyl (meth)acrylate with biological sources; The total weight percentage of the long-chain alkyl ester and isobornyl (meth)acrylate is 15%-60% of the solid content of the emulsion polymer, preferably 20%-40%, and more preferably 22%-35%.

2. A biomass cement-based waterproof emulsion according to claim 1, characterized in that: The weight ratio of the long-chain alkyl ester to isobornyl (meth)acrylate is 4-6:8-12, preferably 5-6:9-11.

3. The biomass cement-based waterproof emulsion according to claim 1, characterized in that: The monomer containing an ethylenically unsaturated group is composed of a hard monomer and a soft monomer, and the weight ratio of the hard monomer to the soft monomer is 2-10:25-35, preferably 3-8:28-33; The hard monomer is a monomer with a glass transition temperature of ≥20°C, including one or more of styrene, methacrylic acid, methyl methacrylate, and vinyl acetate; The soft monomer is a monomer with a glass transition temperature of less than 20° C., including one or more of butyl acrylate, butyl methacrylate, isooctyl acrylate, and ethyl acrylate.

4. The biomass cement-based waterproof emulsion according to claim 1, characterized in that: The long-chain alkyl ester is a C12-C18 alkyl ester monomer, including C12-C18 alkyl (meth)acrylate, cardanol (meth)acrylate, allyl glycidyl ether cardanol ether, glycidyl methacrylate cardanol ether, and hydroxyethyl (meth)acrylate cardanol ether.

5. The biomass cement-based waterproof emulsion according to claim 1, characterized in that: The emulsifier accounts for 0.05%-10% of the total weight of the monomer, preferably 1%-8%, more preferably 2%-5%; The emulsifier is an anionic emulsifier and / or a nonionic emulsifier; The anionic emulsifier includes one or two of fatty alcohol polyoxyethylene ether sulfate, alkyl diphenyl ether sulfonate, sodium lauryl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, and sodium lauryl polyoxyethylene ether sulfate; The nonionic emulsifier includes alkyl polyoxyethylene ether and isomeric alcohol polyoxyethylene ether.

6. The biomass cement-based waterproof emulsion according to claim 1, characterized in that: The initiator is a persulfate or an azo initiator, and the initiator accounts for 0.05%-5% of the total weight of the monomer, preferably 0.1%-3%, and more preferably 0.3%-1%; The monomers further comprise functional monomers and / or cross-linking monomers, wherein the functional monomers and / or cross-linking monomers account for 0.1-5%, preferably 0.5-3%, of the total weight of the monomers; The functional monomers include one or more of acrylic acid, methacrylic acid, itaconic acid, β-acryloxypropionic acid, maleic anhydride, fumaric acid, (meth)acrylamide, hydroxymethylacrylamide, acrylonitrile, hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate; The crosslinking monomer includes one or more of vinyl trimethoxysilane, γ-methacryloxypropyl trimethoxysilane, Momentive silane coupling agent Coatosil MP200, trimethylolpropane triacrylate and 1,6-hexanediol diacrylate.

7. The method for preparing a biomass cement-based waterproof emulsion according to claim 1, wherein: The following steps are involved: (1) Preparation of pre-emulsion: Emulsifier a, all monomers and water are mixed and stirred to obtain a pre-emulsion; (2) Preparation of the bottom material: Add water, emulsifier b and buffer stabilizer into the reactor and stir evenly to obtain the bottom material; (3) Polymerization reaction: add seed emulsion and initiator a to the bottom of the kettle under stirring, then add pre-emulsion and initiator b dropwise at the same time within 2-6 hours, and control the temperature at 83-85°C; (4) Post-treatment: After the addition is completed, keep the mixture at 83-85°C for 30-120 minutes, eliminate the residual monomers, and adjust the pH to obtain the product.

8. The method for preparing a biomass cement-based waterproof emulsion according to claim 7, characterized in that: The emulsifier a is preferably a mixture of an anionic emulsifier and a nonionic emulsifier, and the emulsifier b is an anionic emulsifier; And / or, the mass ratio of the amount of water used in step (1) to the monomer is 1:4-6; the mass ratio of the amount of water used in step (2) to the monomer is 1:2-3; The mass ratio of water to the monomer is 1:4-6; the mass ratio of water to the monomer in step (2) is 1:2-3; And / or, the buffer stabilizer in step (2) includes one or more of cyclodextrin, sodium bicarbonate, ammonium bicarbonate, and sodium dihydrogen phosphate, preferably cyclodextrin, and the amount of the buffer stabilizer added accounts for 0.1-1% of the total mass of the monomer; preferably 0.4-0.8%; And / or, the mass ratio of initiator a to initiator b in step (3) is 1:2-4; And / or, the seed emulsion in step (3) is a seed emulsion having a particle size of 70-100 nm and a solid content of 35-45%, and the amount of the seed emulsion added accounts for 1-5% of the total mass of the monomer; preferably 2-3%; And / or, step (4) eliminates the residual monomers by adding an oxidizing agent and a reducing agent, and adjusts the pH by adding a neutralizing agent; The oxidant includes tert-butyl hydroperoxide and hydrogen peroxide. The amount of the oxidant added is 0.05 wt% to 2 wt% relative to the total weight of the monomer, preferably 0.1 wt% to 1 wt%, preferably, added in the form of an aqueous solution; The reducing agent includes bleaching agent, sodium metabisulfite, FF6M, L-ascorbic acid, and sodium ascorbate. The amount of the reducing agent added is 0.01 wt% to 2 wt% relative to the total weight of the monomers, preferably 0.1 wt% to 1 wt%. Preferably, the reducing agent is added in the form of an aqueous solution. The neutralizing agent includes ammonia water, triethylamine, dimethylethanolamine, and 2-amino-2-methylpropanol.

9. The method for preparing a biomass cement-based waterproof emulsion according to claim 8, characterized in that: The seed emulsion in step (3) is prepared by the following method: (1-1) uniformly mixing water, an emulsifier, a mixed monomer, and an initiator to prepare a pre-emulsion of the seed emulsion; (1-2) Add water and emulsifier to the reactor, mix well, heat to 75-85°C, and add initiator; (1-3) adding 1 wt% to 5 wt% of the pre-emulsion of the seed emulsion in step (1-1) into a reaction kettle, and after the temperature rises to 75-85° C., uniformly adding the remaining pre-emulsion of the seed emulsion dropwise for a total of 2-4 hours. After the addition is complete, cooling to room temperature to obtain a seed emulsion; The mixed monomer is composed of the following components in parts by weight: 17-19 parts of butyl acrylate, 17-19 parts of methyl methacrylate, and 0.7-0.9 parts of methacrylic acid; And / or, the amount of the emulsifier in step (1-1) accounts for the total weight of the mixed monomers 1-15wt%, preferably 5-10wt%; the amount of water accounts for 70-85wt% of the total weight of the mixed monomers, preferably 75-85wt%; the amount of the initiator accounts for 0.1-2wt% of the total weight of the mixed monomers, preferably 0.5-1wt%; And / or, the amount of the emulsifier in step (1-2) accounts for 2-10wt% of the total weight of the mixed monomers, preferably 6-8wt%; the amount of water accounts for 50-70wt% of the total weight of the mixed monomers, preferably 50-60wt%; the amount of the initiator accounts for 0.1-1.5wt% of the total weight of the mixed monomers, preferably 0.6-1.2wt%.

10. A cement-based waterproof coating, characterized in that: The preparation raw materials include the waterproof emulsion according to any one of claims 1 to 9.

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