A concrete waterproofing agent and its preparation method

Abstract

This invention relates to a concrete waterproofing agent and its preparation method. Using hydroxyl acrylate monomers (or hydroxymethyl acrylate), long-chain acrylates (or long-chain methyl acrylates), and short-chain acrylates (or short-chain methyl acrylates) as raw materials, a poly(meth)acrylate polymer containing hydroxyl and long-chain alkyl groups is first prepared by bulk copolymerization. Then, an isocyanate silane coupling agent is used in this polymerization reaction to obtain a silane-containing long-chain alkyl polyacrylate compound (Si@Poly long-chain alkyl acrylate, Si@PLAA). This polymer (Si@PLAA) is then mixed with an emulsifier and a dispersant, and after emulsification, a waterproofing agent emulsion is obtained.

Description

Technical Field

[0001] This invention belongs to the field of building waterproofing, specifically relating to a concrete waterproofing agent and its preparation method. Technical Background

[0002] Since the first use of modern concrete in 1759, it has transformed human lifestyles and living environments. As the world's largest producer and consumer of concrete, China has produced over 2 billion cubic meters of concrete annually for the past five years. Concrete is used to construct bridges, buildings, roads, and various infrastructure projects. Concrete used in dams, bridges, and tunnels, in particular, has very high requirements for seepage prevention, making waterproofing and seepage resistance of concrete increasingly important.

[0003] In the 1970s, as people's understanding of the internal structural characteristics of concrete deepened, concrete admixtures began to be widely used to reduce internal porosity, improve pore structure, and thus enhance the waterproofing and impermeability of concrete. Concrete waterproofing agents are admixtures that can reduce the water absorption or permeability of concrete under hydrostatic pressure, thereby improving its waterproofing, impermeability, and durability. Commonly used waterproofing agents in concrete can be divided into organic and inorganic waterproofing agents. Organic waterproofing agents mainly include fatty acids and their salts, organosilicon compounds, and some polymer emulsions, while inorganic waterproofing agents include ferric chloride, calcium chloride, water glass, and diatomaceous earth series. Fluorinated waterproofing agents account for a large share of organic waterproofing agents. The octyl fluorinated organosilicon resin emulsion provided by patent CN118389060A has good stability, strong adhesion, good impregnation effect, and excellent waterproofing performance after being applied to the concrete surface. However, the fluorinated components involved pose numerous problems for the environment and human safety: fluorinated compounds can release toxic or carcinogenic perfluorinated and polyfluoroalkyl substances (PFAS) and perfluorooctanoic acid (PFOA), threatening soil, water sources, and human health. With increasing environmental awareness and stricter regulations, more and more places are imposing strict restrictions on the use of fluorinated materials. In 2020, the European Union banned the use of PFAS-containing non-stick coatings in food contact materials (such as non-stick cookware and food packaging), and Germany banned the use of PFAS-containing non-stick coatings in household appliances in 2021.

[0004] The market demand for waterproofing agents that comply with green building and sustainable development has increased significantly. Some fluorine-free waterproofing agents have gained widespread attention due to their high durability and chemical stability, making them suitable for the long-term waterproofing needs of building structures. Concrete is a silicate material. Utilizing the unique small molecular structure of silanes, they penetrate the surface of concrete, seeping into the concrete interior several to tens of millimeters deep, distributing themselves on the inner walls of the concrete capillaries, even reaching the smallest capillary walls. Under the influence of air and water in the capillaries, silanes hydrolyze to form silanols. The newly generated silanols react with the hydroxyl groups in the silicate to form siloxane chains with -Si-R* groups at the ends, which condense together on the substrate surface to form a strong, rigid-flexible, water-repellent network structure of hydrophobic layer. This gives the concrete surface a waterproof effect and prevents water from seeping into the concrete structure, thus protecting the base layer.

[0005] Patent CN119039879A designs an organosilicon waterproofing agent that can be used on the surfaces of various building materials, exhibiting superhydrophobicity, long-lasting weather resistance, and excellent scratch resistance. Patent US4769405A describes a water-based organosilicon emulsion coating material that forms a thin film coating with excellent durability and waterproof properties. However, silane polymers are relatively more expensive, and silanes are incompatible with many polymers. The advantage of acrylate polymers lies in their good compatibility with other polymers or copolymers, such as polyurethanes and polysiloxanes.

[0006] Acrylic polymers are widely used in adhesives, sealants, and coatings due to their relatively low cost, as disclosed in patents US6169043B, EP0417570A1, and US5021506A. Coating materials composed of polyacrylic resins form a coating through curing, but the weather resistance of this coating itself is unsatisfactory, and the physical properties of the film gradually deteriorate under long-term exposure to ultraviolet light, resulting in a loss of elasticity.

[0007] Waterproofing agents made from standalone silanes and acrylate-based polymers each have distinct advantages and disadvantages. Copolymers of polyacrylates with monomers containing Si are well-known. Patents US2015119536A1 and US2013012653A1 describe the preparation of copolymers from organosilicon monomers and acrylate monomers. Patent WO2020172895A1 mentions the preparation of hydrophobic films using modified silica and polyacrylate emulsions, exhibiting excellent waterproofing properties but insufficient impermeability. Patent CN115108754A discloses a concrete surface reinforcing hardener and its preparation method, using isooctyltriethoxysilane (DB-H538), whose alkoxy groups can provide good adhesion to the substrate after hydrolysis or crosslink with each other, improving waterproofing capabilities. Patent CN118006150A discloses the reaction of propyltriethoxysilane (IPTS) with olefin polymers, where the isocyanate group (-NCO) and hydroxyl group (-OH) react to yield urethane (-NHCOO-), which improves impermeability. If water is present in the reaction system, the isocyanate group preferentially reacts with water to generate amines and carbon dioxide. Literature reports on the post-polymerization modification of hydroxyl-functionalized polymers with isocyanate groups (Macromolecules 2011, 44, 4828-4835), where hydroxyl-containing monomers can be bulk polymerized, achieving high end-group and side-chain conversion rates (typically >98%) at ambient temperatures, with little or no byproduct formation.

[0008] Blends of silanes and acrylate-based polymers are thermodynamically unstable, exhibiting changes in properties and macroscopic phase separation over time. Thermodynamically unstable mixtures can be effectively polymerized via emulsion polymerization, but kinetic means are needed to maintain system stability within the reaction time, as in the emulsion polymerization of styrene in water. Partially polymerized oligomers can be emulsified before further emulsion polymerization. Emulsifiers may adsorb onto particle surfaces, altering surface charge or hydrophobicity; for example, long-chain emulsifiers can enhance hydrophobicity. Selecting a suitable emulsifier can disperse and stabilize the emulsion; ionic emulsifiers are preferred because they impart an electrostatic charge to the dispersed particles, stabilizing the emulsion dispersion through electrostatic repulsion.

[0009] Long-chain alkanes, with their abundant nonpolar methylene structures (-CH2-), are the best alternative to difluoromethylene (-CF2-) (more hydrophobic than ester groups (-COO-), amide groups (-CO-NH-), and ether bonds (ROR′). In terms of solubility, long-chain alkanes are poorly soluble in water due to the significant difference in polarity between their molecular structures and water. Patent CN106536622A discloses acrylate copolymers containing long carbon chains that possess excellent waterproof properties. An advantage of acrylate polymers is their good compatibility with other polymers or copolymers, such as polyurethanes and polysiloxanes.

[0010] This invention relates to a concrete waterproofing agent and its preparation method. Using hydroxyl acrylate monomers (or hydroxymethyl acrylate), long-chain acrylates (or long-chain methyl acrylates), and short-chain acrylates (or short-chain methyl acrylates) as raw materials, a poly(meth)acrylate polymer containing hydroxyl and long-chain alkyl groups is first prepared by bulk copolymerization. Then, an isocyanate-based silane coupling agent is used in this polymerization reaction to obtain a silane-containing long-chain alkyl polyacrylate compound (Si@Poly long-chain alkyl acrylate, Si@PLAA). This polymer (Si@PLAA) is then mixed with an emulsifier and a dispersant, and after emulsification, a waterproofing agent emulsion is obtained. The preparation route of the fluorine-free waterproofing agent of this invention is shown in the appendix. Figure 1 .

[0011] This emulsion contains long-chain alkyl structures, exhibiting strong hydrophobicity and significantly improving the waterproofing performance of concrete compared to traditional polyacrylate waterproofing agents. The isocyanate-based silane coupling agent-modified polyacrylate undergoes further internal cross-linking, enhancing the waterproofing agent's durability. Furthermore, the grafted silane structure possesses an extremely stable Si-O-Si structure, forming strong covalent bonds with the silicate matrix in concrete pores and capillaries, resulting in siloxane chains with -Si-OH groups at the ends, exhibiting excellent hydrophobic effects after condensation. The emulsifier chosen is octadecammonium acetate or octadecyltrimethylammonium chloride, long-chain surfactants that adsorb onto the polymer, further enhancing the waterproofing effect. The emulsion-formulated waterproofing agent exhibits good flowability and brushability, facilitating application. Moreover, the selected raw materials are non-toxic or low-toxic, containing no organic solvents, making it more environmentally friendly and suitable for construction workers. This formulation and process result in a concrete waterproofing agent with significant advantages in waterproofing performance, durability, environmental friendliness, and application performance, meeting the demands of modern construction for high-performance waterproofing materials. Summary of the Invention

[0012] This invention provides poly(meth)acrylate polymers of general formula (I) containing hydroxyl groups and long-chain alkyl groups:

[0013]

[0014] in:

[0015] n, m, and x are integers from 2 to 60;

[0016] R 1 It is a straight-chain or branched alkyl group with 1 to 4 carbon atoms;

[0017] R 3 Alkyl groups consisting of an even number of carbon atoms, ranging from 8 to 18, that are either straight-chain or branched.

[0018] R 5 -CH2CH2-, -CH2CH2CH2-;

[0019] R 2 R 4 R 6 It is hydrogen or methyl (-CH3).

[0020] The specific preparation method of formula (I) prepared in this invention is completed by the following step S1.

[0021] S1: Monomer A, monomer B, monomer C, and initiator are reacted in a nitrogen-protected reactor at 50-80℃ with stirring for 2-6 hours to obtain the bulk polymerization product.

[0022] The reaction equation is as follows:

[0023]

[0024] In S1, monomer A can be any one or a combination of methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BA), isobutyl acrylate (IBA), methyl methacrylate (MMA), ethyl methacrylate (EMA), isopropyl methacrylate (IPMA), butyl methacrylate (BMA), and isobutyl methacrylate (IBMA).

[0025] In S1, monomer B can be any one or a combination of isooctyl acrylate (2-EHA), dodecyl acrylate (LA), tetradecyl acrylate (TA), hexadecyl acrylate (HA), octadecyl acrylate (SA), dodecyl methacrylate (LMA), tetradecyl methacrylate (TMA), hexadecyl methacrylate (HMA), and octadecyl methacrylate (SMA).

[0026] In S1, monomer C can be any one of hydroxyethyl acrylate (HEA), hydroxyethyl methacrylate (HEMA), hydroxypropyl acrylate (HPA), and hydroxypropyl methacrylate (HPMA).

[0027] In S1, the molar ratio of monomer A to monomer B is 1:4-2:1, preferably 2:1; the molar ratio of monomer A to monomer C is 5:1-7:1, preferably 6:1.

[0028] In step S1, the initiator is an azo initiator or a peroxide initiator. Specifically, the azo initiator can be 2,2'-azobisisobutyronitrile (AIBN), 4,4'-azobis(4-cyanopentanoic acid) (ACVA), or azobisisoheptanenitrile (ABVN); the peroxide initiator can be tert-butyl hydroperoxide (TBHP) or benzoyl peroxide (BPO). AIBN, ABVN, and BPO are preferred initiators. The initiator used accounts for 0.5-0.7% of the total weight of the polymerizing monomers, preferably 0.6%.

[0029] In step S1, the reaction temperature is 50-80℃, preferably 60-70℃. The reaction time is 2-6 hours, preferably 3-4 hours.

[0030] This invention provides a silane-containing long-chain alkyl polyacrylate compound of general formula (II) (Si@Poly long-chain alkyl acrylate, Si@PLAA):

[0031]

[0032] in:

[0033] n, m, and x are integers from 2 to 60;

[0034] R 1 It is a straight-chain or branched alkyl group with 1 to 4 carbon atoms;

[0035] R 3 Alkyl groups consisting of an even number of carbon atoms, ranging from 8 to 18, that are either straight-chain or branched.

[0036] R 5 -CH2CH2-, -CH2CH2CH2-;

[0037] R 2 R 4 R 6 It is hydrogen or methyl (-CH3);

[0038] R 7 It is methyl (-CH3) or ethyl (-CH3) 2c CH3).

[0039] The specific preparation method of the Si@PLAA waterproofing emulsion prepared in this invention consists of the following steps:

[0040] S2-1. In a nitrogen-protected reactor, monomer D is slowly added dropwise to the polymer shown in formula (I), a catalyst is added, and the reaction is carried out at 20-60°C with stirring for 1-3 hours to obtain Si@PLAA;

[0041] S2-2. Add emulsifier and water to Si@PLAA and emulsify to obtain Si@PLAA waterproof emulsion.

[0042] The reaction equation is as follows:

[0043] In S2-1, monomer D is one of propyltriethoxysilane isocyanate (IPTS) or 3-isocyanopropyltrimethoxysilane (CFS-006).

[0044] In S2-1, the catalyst is dibutyltin dilaurate (DBDTL), dibutyltin diacetate (ba2726), or stannous octoate, accounting for 0.15–0.25% of the weight of Si@PLAA. Preferably, the catalyst is DBDTL; more preferably, the weight is 0.2%.

[0045] In S2-1, the molar ratio of monomer D to the hydroxyl group in the acrylate is 1:1.

[0046] In step S2-1, the temperature reaction is between 20°C and 60°C, preferably between 30°C and 40°C. The reaction time is 1-3 hours, preferably 2 hours.

[0047] In S2-2, the emulsifier is octadecammonium acetate or octadecyltrimethylammonium chloride, accounting for 4% of the total weight.

[0048] In step S2-2, deionized water accounts for 60-70% of the total weight, preferably 70%.

[0049] In step S2-2, the emulsification temperature is between 40°C and 70°C, preferably between 50°C and 60°C; the emulsification time is 0.5-1 hour, preferably 1 hour.

[0050] The invention possesses the following beneficial effects: The concrete waterproofing agent of the present invention has a long-chain alkyl structure, exhibiting strong hydrophobicity, which significantly improves the waterproofing performance of concrete compared to traditional polyacrylate waterproofing agents. The isocyanate silane coupling agent-modified polyacrylate undergoes further internal cross-linking, enhancing the durability of the waterproofing agent; on the other hand, the grafted silane structure has an extremely stable Si-O-Si structure, which can form strong covalent bonds with the silicate matrix in the pores and capillaries of concrete, forming siloxane chains with -Si-OH groups at the ends, exhibiting excellent hydrophobic effects after condensation (see attached diagram for the waterproofing principle of the fluorine-free waterproofing agent of the present invention). Figure 2The emulsifier chosen is octadecammonium acetate or octadecyltrimethylammonium chloride, a long-chain surfactant that adsorbs onto the polymer, further enhancing the waterproofing effect. The emulsion-formed waterproofing agent exhibits good flowability and brushability, facilitating application. Furthermore, the selected raw materials are non-toxic or low-toxic, containing no organic solvents, making it more environmentally friendly and suitable for construction workers. This formulation and process result in a concrete waterproofing agent with significant advantages in waterproofing performance, durability, environmental friendliness, and application performance, meeting the demands of modern construction for high-performance waterproofing materials. Attached Figure Description

[0051] Appendix Figure 1 Schematic diagram of waterproofing agent preparation.

[0052] Appendix Figure 2 : Schematic diagram of the principle of the synthetic waterproofing agent of this invention acting on concrete. Detailed Implementation

[0053] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0054] Example 1

[0055] This embodiment provides a method for preparing a concrete waterproofing agent, including the following steps:

[0056] a) Poly(meth)acrylate polymers containing hydroxyl and long-chain alkyl groups:

[0057] 10g of methyl methacrylate (MMA), 20g of butyl acrylate (BA), 10g of isooctyl acrylate (2-EHA), 10g of dodecyl acrylate (LA), 4g of hydroxyethyl acrylate (HEA), and 0.3g of BPO initiator (Taizhou Zhongteng Chemical Materials) were added to a three-necked flask purged with nitrogen. The mixture was heated to 50°C and reacted for 2 hours to obtain a polyacrylate polymer through bulk polymerization.

[0058] b) Si@PLAA waterproofing emulsion:

[0059] In a nitrogen-purged three-necked flask, 4g of IPTS was slowly added dropwise to a polyacrylate polymer, followed by 0.1g of catalyst DBDTL (Shanghai Xindian Chemical Materials). The mixture was reacted at 20°C for 1 hour to obtain Si@PLAA. Si@PLAA, 90g of deionized water, and 6g of octadecammonium acetate (Condis Chemical) were then added to a high-pressure, high-speed homogenizer at 15,000 rpm and 0.2 MPa, and homogenized at 40°C for half an hour to obtain a waterproofing agent.

[0060] Example 2

[0061] This embodiment provides a method for preparing a concrete waterproofing agent, including the following steps:

[0062] a) Poly(meth)acrylate polymers containing hydroxyl and long-chain alkyl groups:

[0063] 15g of ethyl methacrylate (EMA), 15g of isobutyl acrylate (IBA), 5g of dodecyl acrylate (LA), 15g of tetradecyl methacrylate (TMA), 5g of hydroxyethyl methacrylate (HEMA), and 0.3g of AIBN initiator (Shandong Qiangsen Chemical Co., Ltd.) were added to a three-necked flask purged with nitrogen. The mixture was heated to 60°C and reacted for 2.5 hours to obtain a polyacrylate polymer through bulk polymerization.

[0064] b) Si@PLAA Waterproofing Emulsion

[0065] In a nitrogen-purged three-necked flask, 5g of CFS-006 was slowly added dropwise to a polypropylene polymer, along with 0.1g of catalyst DBDTL (Xindian Chemical Materials (Shanghai)). The mixture was reacted at 30°C for 1 hour to obtain Si@PLAA. Si@PLAA, 100g of deionized water, and 6g of octadecyltrimethylammonium chloride (Guangzhou Zhonghai Chemical) were then added to a high-pressure, high-speed homogenizer at 15,000 rpm and 0.2 MPa, and homogenized at 50°C for half an hour to obtain a waterproofing agent.

[0066] Example 3

[0067] This embodiment provides a method for preparing a concrete waterproofing agent, including the following steps:

[0068] a) Poly(meth)acrylate polymers containing hydroxyl and long-chain alkyl groups:

[0069] 10g of isopropyl methacrylate (IPMA), 25g of butyl acrylate (BA), 10g of tetradecyl acrylate (TA), 15g of hexadecyl methacrylate (HMA), 5g of hydroxypropyl acrylate (HPA), and 0.3g of ABVN initiator (Jiangsu Gaoqi New Materials Co., Ltd.) were added to a three-necked flask purged with nitrogen. The mixture was heated to 65°C and reacted for 3 hours to obtain a polyacrylate polymer through bulk polymerization.

[0070] b) Si@PLAA waterproofing emulsion:

[0071] In a nitrogen-purged three-necked flask, 5g of IPTS was slowly added dropwise to a polyacrylate polymer, followed by 0.1g of catalyst ba2726 (Wuhan Camick Technology). The reaction was carried out at 40°C for 1.5 hours to obtain Si@PLAA. Si@PLAA, 110g of deionized water, and 7g of octadecammonium acetate (Condis Chemical) were then added to a high-pressure, high-speed homogenizer at 15,000 rpm and 0.2 MPa, and homogenized at 60°C for half an hour to obtain a waterproofing agent.

[0072] Example 4

[0073] This embodiment provides a method for preparing a concrete waterproofing agent, including the following steps:

[0074] a) Poly(meth)acrylate polymers containing hydroxyl and long-chain alkyl groups:

[0075] 25g of butyl acrylate (BA), 10g of methyl acrylate (MA), 5g of isooctyl acrylate (2-EHA), 20g of octadecyl acrylate (SA), 6g of hydroxypropyl methacrylate (HPMA), and 0.3g of BPO initiator (Taizhou Zhongteng Chemical Materials) were added to a three-necked flask purged with nitrogen. The mixture was heated to 70°C and reacted for 3.5 hours to obtain a polyacrylate polymer through bulk polymerization.

[0076] b) Si@PLAA waterproofing emulsion:

[0077] In a nitrogen-purged three-necked flask, 6 g of CFS-006 was slowly added dropwise to a polyacrylate polymer, along with 0.1 g of stannous octoate catalyst (Wuhan Jixin Yibang Biotechnology Co., Ltd.). The reaction was carried out at 20°C for 2 hours to obtain Si@PLAA. Si@PLAA, 120 g of deionized water, and 8 g of octadecyltrimethylammonium chloride (Guangzhou Zhonghai Chemical) were then added to a high-pressure, high-speed homogenizer at 15,000 rpm and 0.2 MPa, and homogenized at 70°C for half an hour to obtain a waterproofing agent.

[0078] Example 5

[0079] This embodiment provides a method for preparing a concrete waterproofing agent, including the following steps:

[0080] a) Poly(meth)acrylate polymers containing hydroxyl and long-chain alkyl groups:

[0081] 25g of butyl methacrylate (BMA), 10g of ethyl acrylate (EA), 5g of hexadecyl acrylate (HA), 25g of octadecyl methacrylate (SMA), 6g of hydroxyethyl methacrylate (HEMA), and 0.3g of AIBN initiator (Shandong Qiangsen Chemical Co., Ltd.) were added to a three-necked flask purged with nitrogen. The mixture was heated to 80°C and reacted for 4 hours to obtain a polyacrylate polymer through bulk polymerization.

[0082] b) Si@PLAA waterproofing emulsion:

[0083] In a nitrogen-purged three-necked flask, 6g of IPTS and 0.1g of catalyst DBDTL (Shanghai Xindian Chemical Materials) were slowly added dropwise to a polyacrylate polymer. The mixture was reacted at 30°C for 3 hours to obtain Si@PLAA. Si@PLAA, 130g of deionized water, and 8g of octadecammonium acetate (Condis Chemical) were then added to a high-pressure, high-speed homogenizer at 15,000 rpm and 0.2 MPa, and homogenized at 50°C for 1 hour to obtain a waterproofing agent.

[0084] The operating steps for Examples 6-10 are the same as those for Examples 1-5 above. The raw materials are shown in Table 1, and the monomer components are shown in Table 2.

[0085] Table 1. Raw material list for preparing concrete waterproofing agent (values ​​are in grams).

[0086]

[0087] Note: Emulsifier A is octadecammonium acetate, and emulsifier B is octadecyltrimethylammonium chloride.

[0088] *Monomer ratios are shown in Table 2

[0089] Table 2. Monomers for preparing concrete waterproofing agents (values ​​in grams).

[0090]

[0091] Comparative Example 1

[0092] 30g of methyl methacrylate (MMA), 5g of butyl acrylate (BA), 5g of isooctyl acrylate (2-EHA), 25g of octadecyl acrylate (SA), 6g of hydroxyethyl acrylate (HEA), 0.3g of BPO initiator, 150g of deionized water, and 8g of octadecylamine acetate were added to a high-pressure, high-speed homogenizer at 15,000 rpm and 0.2 MPa. The homogenizer was homogenized at 50°C for half an hour. After homogenization, the mixture was transferred to a three-necked flask purged with nitrogen and heated to 60°C. The reaction was carried out for 5 hours, and the emulsion polymerization yielded the waterproofing agent.

[0093] Comparative Example 2

[0094] a) Add 50g of methyl methacrylate (MMA), 20g of butyl acrylate (BA), 6g of hydroxyethyl acrylate (HEA), and 0.3g of BPO initiator to a three-necked flask purged with nitrogen, heat to 60°C, and react for 5 hours to obtain a polyacrylate polymer by bulk polymerization.

[0095] b) Slowly add 6g of IPTS and 0.1g of catalyst DBDTL to the polyacrylate polymer, react at 30℃ for 1h to obtain a polyacrylate polymer containing organosilicon. Add the polyacrylate polymer containing organosilicon, 130g of deionized water, and 8g of octadecammonium acetate to a high-pressure, high-speed homogenizer at 15,000rpm and 0.2MPa, homogenize at 50℃ for half an hour to obtain a waterproofing agent.

[0096] Comparative Example 3

[0097] a) Add 30g of methyl methacrylate (MMA), 5g of butyl acrylate (BA), 5g of isooctyl acrylate (2-EHA), 25g of octadecyl acrylate (SA), and 6g of hydroxyethyl acrylate (HEA) to a three-necked flask purged with nitrogen, heat to 60°C, and react for 5 hours to obtain a polyacrylate polymer by bulk polymerization.

[0098] b) Slowly add 6g of IPTS and 0.1g of catalyst DBDTL to the polyacrylate polymer, react at 30℃ for 1h to obtain Si@PLAA. Add Si@PLAA, 130g of deionized water and 8g of sodium dodecyl sulfate (SDS) to a high-pressure high-speed homogenizer at 15,000rpm and 0.2MPa, homogenize at 50℃ for half an hour to obtain the waterproofing agent.

[0099] Comparative Example 4

[0100] a) Add 30g of methyl methacrylate (MMA), 5g of butyl acrylate (BA), 5g of isooctyl acrylate (2-EHA), 25g of octadecyl acrylate (SA), 6g of hydroxyethyl acrylate (HEA), 36g of isooctyltriethoxysilane (DB-H538), and 0.1g of DBDTL to a three-necked flask purged with nitrogen. Heat to 60°C and react for 5 hours to obtain a polypropylene polymer containing organosilicon through bulk polymerization.

[0101] b) Add the silicone-containing polypropylene polymer, 130g of deionized water, and 8g of octadecammonium acetate to a high-pressure, high-speed homogenizer at 15,000 rpm and 0.2 MPa, and homogenize at 50°C for half an hour to obtain a waterproofing agent.

[0102] Performance testing

[0103] The concrete waterproofing agents of Examples 1 to 10 and Comparative Examples 1 to 4 were subjected to 28d / 56d seepage pressure (MPa) and physical property tests. The test methods are as follows:

[0104] C30 concrete was used for the concrete test specimens (the specimens were formed using 10cm x 10cm x 10cm steel concrete molds, and no oil-based release agent was used on the inner surface of the molds).

[0105] 1. 28d / 56d seepage resistance pressure (MPa): Tested according to the test method in standard GB18445-2012.

[0106] 2. Physical performance testing: Tested in accordance with standard GB / T 23445-2009 "Polymer Cement Waterproof Coating".

[0107] The test results are shown in Tables 3 and 4:

[0108] Table 3. Testing of the seepage resistance pressure (MPa) of concrete waterproofing agent at 28d / 56d

[0109]

[0110]

[0111] As shown in Table 3, compared to the baseline concrete, Examples 1 to 10 exhibited improved 28-day and 56-day impermeability pressures (MPa). Compared to Comparative Example 1, the waterproofing agent made with isocyanate-triethoxysilane-modified polyacrylate showed a significant improvement in impermeability pressure compared to the unmodified waterproofing agent. Compared to Comparative Example 4, it showed a slight improvement in impermeability pressure compared to the isooctyltriethoxysilane-modified waterproofing agent. This demonstrates that using isocyanate-triethoxysilane-modified polyacrylate to improve impermeability is entirely feasible. Comparative Examples 2 and 3 show that long-chain alkanes and emulsifiers enhance the impermeability of the waterproofing agent.

[0112] As shown in Table 4, the tensile strength of the untreated concrete in Examples 1 to 10 reached over 3 MPa. After heat treatment, the tensile strength retention rate reached over 90%, and after alkali treatment, the tensile strength retention rate reached 90%. The elongation at break of the concrete waterproofing agent reached over 3 MPa. After heat treatment, the elongation at break retention rate reached 80%, and after alkali treatment, the elongation at break retention rate reached 80%. The bond strength of the waterproofing agent reached over 1 MPa. After heat treatment, the bond strength remained above 1 MPa with a slight decrease, and after alkali treatment, the bond strength remained above 1 MPa with a slight decrease. The compressive strength of the concrete waterproofing agent reached over 1 MPa and successfully passed the 0.3 MPa, 30-minute impermeability test. All test data were superior to the reference concrete and comparative examples 1 to 4. This indicates that propyltriethoxysilane isocyanate, long-chain alkanes, and long-chain emulsifiers all contribute to improving the tensile strength, elongation at break, bond strength, and impermeability of concrete.

Claims

1. A method for preparing a concrete waterproofing agent, characterized in that, Includes the following steps: S1. Mix monomer A, monomer B, monomer C, and initiator in a nitrogen-protected reactor at 50-80℃ with stirring for 2-6 hours to obtain a poly(meth)acrylate polymer containing hydroxyl and long-chain alkyl groups through bulk polymerization. The molar ratio of monomer A to monomer B is 1:4-2:1, and the molar ratio of monomer A to monomer C is 5:1-7:

1. Among them, monomer A has the structure shown in formula (I): （I） Monomer B has the structure shown in formula (II): (II) Monomer C has the structure shown in formula (III): (III) in: R 1 It is a straight-chain or branched alkyl group with 1 to 4 carbon atoms; R 3 Alkyl groups consisting of an even number of carbon atoms, ranging from 8 to 18, that are either straight-chain or branched. R 5 for , ; R 2 R 4 R 6 It can be hydrogen or methyl; S2-1. In a nitrogen-protected reactor, monomer D is slowly added dropwise to a poly(meth)acrylate polymer containing hydroxyl and long-chain alkyl groups. A catalyst is added, and the mixture is stirred at 20-60°C for 1-3 hours to obtain a silane-containing long-chain alkyl polyacrylate compound (Si@PLAA). Among them, monomer D is one of propyltriethoxysilane or 3-isocyanopropyltrimethoxysilane. S2-2. Add emulsifier and water to the silane-containing long-chain alkyl polyacrylate compound (Si@PLAA) prepared in S2-1, and emulsify and disperse to obtain Si@PLAA waterproofing emulsion.

2. The method for preparing the concrete waterproofing agent as described in claim 1, characterized in that: Monomer A is any one or a combination of methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, and isobutyl methacrylate. Monomer B is any one or a combination of isooctyl acrylate, dodecyl acrylate, tetradecyl acrylate, hexadecyl acrylate, octadecyl acrylate, dodecyl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate, and octadecyl methacrylate; Monomer C is any one of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate.

3. The method for preparing the concrete waterproofing agent as described in claim 1, characterized in that: The molar ratio of monomer D to the hydroxyl groups in the poly(meth)acrylate polymer containing hydroxyl and long-chain alkyl groups is 1:

1.

4. The method for preparing the concrete waterproofing agent as described in claim 1, characterized in that: The initiator described in S1 is any one of 2,2'-azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide.

5. The method for preparing the concrete waterproofing agent as described in claim 1, characterized in that: The catalyst described in S2-1 is any one of dibutyltin dilaurate, dibutyltin diacetate, and stannous octoate.

6. The method for preparing the concrete waterproofing agent as described in claim 1, characterized in that: The emulsifier mentioned in S2-2 is either octadecylamine acetate or octadecyltrimethylammonium chloride.

7. A concrete waterproofing agent, characterized in that, The concrete waterproofing agent is prepared by the preparation method according to any one of claims 1 to 6.

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