Multifunctional admixture, its preparation method and application in concrete protection

Abstract

This invention belongs to the technical field of high-performance concrete protective materials, specifically relating to a multifunctional additive, its preparation method, and its application in concrete protection. The multifunctional additive has a specific structural formula, and its molecule simultaneously contains hydrolyzable alkoxy groups, hydrophilic polyether segments, and reactive organic functional groups. This additive can be directly added to silane pastes, significantly improving the storage stability of the paste. Furthermore, before subsequent painting, it can eliminate oil shrinkage by homogenizing interfacial tension through its polyether segments, and simultaneously, through its active groups, it forms chemical bonds between coating layers, thereby greatly improving interlayer adhesion and the overall durability of the system. This invention also provides a preparation method for the additive, a silane paste formulation containing the additive, and a concrete protective coating system constructed using the paste and its application method.

Description

Technical Field

[0001] This invention belongs to the technical field of high-performance concrete protective materials, specifically relating to a multifunctional additive, its preparation method, and its application in concrete protection. Background Technology

[0002] As modern concrete structures face increasingly prominent durability challenges under harsh service environments, particularly performance degradation caused by chloride erosion, freeze-thaw damage, carbonation, and chemical corrosion, traditional single-protection technologies are no longer sufficient to meet the needs of long-term protection. Against this backdrop, the concept of composite protection systems has emerged. The combination of "silane paste + high-performance topcoat (such as epoxy paint or polyurethane paint)" has gradually become an important protective measure in fields such as cross-sea bridges, port projects, and industrial plants due to its synergistic effect of internal hydrophobicity and surface shielding. This system aims to construct a dual protection mechanism of "penetration modification - surface shielding": the silane paste penetrates deep into the concrete through capillary action, forming a hydrophobic organosilicon resin network that significantly reduces the substrate's water absorption and chloride ion migration rate, achieving deep protection; while the high-performance paint applied to the surface constructs a continuous and dense physical barrier, directly resisting surface damage such as abrasion, ultraviolet radiation, and chemical erosion. Theoretically, the combination of these two materials can overcome the limitations of single materials in terms of protection dimensions and improve the reliability and longevity of the system through layered protection.

[0003] However, this composite system suffers from a series of prominent technical problems in practical engineering applications, severely restricting its protective effect and engineering reliability. First, poor interlayer adhesion is a core challenge: after the silane paste cures, it forms a low-surface-energy, chemically inert hydrophobic layer on the concrete surface, making it difficult for subsequent organic paints to effectively wet and spread. Interlayer contact is often only physical, resulting in weak adhesion and easy coating peeling. Second, the paint layer is highly susceptible to "oil shrinkage" (pinholes): due to the extreme mismatch in surface tension between the silane layer and the paint layer, and the potential for microscopic inhomogeneity or residual low-surface-energy substances in the silane layer, the paint immediately shrinks after application, forming dot-like or crater-like defects, severely damaging the coating's appearance and integrity. Furthermore, the silane paste itself has storage stability issues; traditional products often experience phase separation or sedimentation during long-term static storage due to the instability of the emulsion system, affecting performance and ease of application.

[0004] Therefore, existing technologies have not yet systematically solved multiple problems in composite protection systems, such as poor adhesion, oil shrinkage defects, and material stability. This makes it difficult to fully realize the theoretical advantages of the system in practice, affecting the cost-effectiveness of engineering maintenance cycles and the entire life cycle. There is an urgent need for an innovative technology that addresses the root causes of these problems by synergistically solving them through material compatibility and construction coordination, in order to promote the development of concrete composite protection technology towards higher reliability, construction adaptability, and long-term durability. Summary of the Invention

[0005] In view of the problems and shortcomings of the existing technology, the present invention aims to provide a multifunctional additive, its preparation method and its application in concrete protection.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The first aspect of this invention provides a multifunctional additive, the general structural formula of which is:

[0007] Wherein, R is any one of H, CH2CH(O)CH2, NH2, COOH, SO3H, and PO3H2; R 1 R 2 R 3 R 4 Each of the following is an alkyl group from C1 to C4; a is an integer from 1 to 50; b is an integer from 1 to 200; c is an integer from 0 to 100; d is an integer from 0 to 50; c+d≥1; x is an integer from 0 to 30; y is an integer from 1 to 40; m is an integer from 0 to 2; n is an integer from 0 to 2; EO is ethylene oxide; PO is propylene oxide.

[0008] Preferably, the weight-average molecular weight of the multifunctional additive is 5000-15000 g / mol.

[0009] The second aspect of this invention provides a method for preparing the multifunctional adjuvant described in the first aspect, comprising the following steps: Under an inert gas atmosphere, the solvent, hydrogen-containing polysiloxane, and allyl polyether are sequentially added to the reactor, stirred, and heated to 70–90°C. The Karstedt catalyst is then added, and the reaction is stirred until the reaction system changes from turbid to clear. The reaction is then maintained at this temperature for 0.5–1 hour. Then, an organosilicon monomer is added to the reaction system, and the reaction continues for another 0.5–1 hour. After the reaction is complete, the solvent in the reaction system is removed to obtain the multifunctional additive.

[0010] Preferably, the allyl polyether has the following structural formula:

[0011] Where R is any one of H, CH2CH(O)CH2, NH2, COOH, SO3H, and PO3H2, x is an integer from 0 to 30, and y is an integer from 1 to 40.

[0012] Preferably, the structural formula of the hydrogen-containing polysiloxane is:

[0013] Where z is an integer from 2 to 200, and b is an integer from 1 to 200.

[0014] Preferably, the solvent is any one of toluene, xylene, isopropanol, and butanol.

[0015] Preferably, the weight-average molecular weight of the allyl polyether is 300–1200 g / mol.

[0016] Preferably, the organosilicon monomer is at least one selected from vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, and 3-methacryloyloxypropyltriethoxysilane.

[0017] Preferably, the hydrogen-containing polysiloxane is prepared by the following method: under inert gas protection, cyclic methylsiloxane, hydrogen-containing silicone oil and hexamethyldisiloxane are added sequentially to a reactor, stirred and heated to 60-80°C, an acidic catalyst is added to the reactor, and the reaction is maintained at 60-80°C for 4-12 hours; after the reaction is completed, the reaction system is cooled to room temperature, a neutralizing agent is added to the reaction system to adjust the pH of the reaction system to 7-8, then the system is filtered, the filtrate is collected, and water and small molecule substances (unreacted raw materials, small molecule oligomers) in the filtrate are removed by vacuum to obtain the hydrogen-containing polysiloxane.

[0018] Preferably, the cyclic methylsiloxane is at least one of hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecylmethylcyclohexasiloxane (D6).

[0019] Preferably, the acidic catalyst is any one of sulfuric acid, methanesulfonic acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid.

[0020] Preferably, the neutralizing agent is any one of sodium bicarbonate, sodium carbonate, sodium hydroxide, potassium hydroxide, potassium carbonate, potassium hydroxyl carbonate, ammonium carbonate, ammonia, ammonium carbonate, and ammonium bicarbonate.

[0021] Preferably, the reactions involved in the preparation method of the multifunctional adjuvant are as shown in reaction formulas (1) and (2): Reaction formula (1):

[0022] Where z is an integer from 2 to 200; b is an integer from 1 to 200; a is an integer from 1 to 50; e is an integer from 1 to 150; z = a + e; R is any one of H, CH2CH(O)CH2, NH2, COOH, SO3H, and PO3H2; x is an integer from 0 to 30; and y is an integer from 1 to 40.

[0023] Reaction (2):

[0024] Where a is an integer from 1 to 50; b is an integer from 1 to 200; e is an integer from 1 to 150; c is an integer from 0 to 100; d is an integer from 0 to 50; and c + d ≥ 1, e = c + d; R is any one of H, CH2CH(O)CH2, NH2, COOH, SO3H, and PO3H2; R 1 R 2 R 3 R 4 Each of the following is an alkyl group from C1 to C4; x is an integer from 0 to 30; y is an integer from 1 to 40; m is an integer from 0 to 2; n is an integer from 0 to 2.

[0025] A third aspect of the present invention provides a silane paste comprising the multifunctional additives described in the first aspect above.

[0026] Preferably, the silane paste is mainly composed of the following raw materials by weight percentage: Emulsifier 1%–5%, alkoxysilane 75%–82%, multifunctional additive 0.1%–2%, thickener 0.5%–1%, water 15%–20%, preservative 0.5%–1%, bactericide 0.5%–1%.

[0027] The fourth aspect of the present invention provides the application of the silane paste described in the third aspect above in concrete protection or concrete protective coating systems.

[0028] The fifth aspect of this invention provides a method for constructing a concrete protective coating system, comprising the following steps: The silane paste described in the third aspect above is applied to the surface of a concrete substrate to form a silane paste layer. After an interval of 1 to 7 days, a protective paint is applied to the surface of the silane paste layer to obtain a concrete protective coating system.

[0029] Preferably, the protective paint is at least one of epoxy resin paint, polyurethane paint, acrylic paint, and fluorocarbon paint.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention integrates three major functions—enhancing storage stability, improving interfacial compatibility, and achieving chemical bonding—into a single additive structure through molecular design. This additive, when added to a silane paste, simultaneously solves three problems: easy separation of the paste, oil shrinkage during paint application, and insufficient interlayer adhesion, all with a single addition.

[0031] 2. This invention addresses the root cause of defects by rapidly homogenizing interfacial tension through the polyether segments in the additives during paint application. This fundamentally disrupts the mechanical conditions for pinhole formation, proactively preventing oil shrinkage and ensuring a continuous, complete, and aesthetically pleasing paint coating.

[0032] 3. This invention utilizes the active groups at both ends of the additive to chemically react with the underlying substrate and the upper paint layer, respectively, to construct a stable, integrated structure in situ of "substrate-silane layer-chemical bridge-paint layer". This structure achieves a fundamental improvement in interlayer adhesion from physical adsorption to chemical bonding, enabling the protective system to withstand severe tests such as stress and damp heat cycling for extended periods, significantly improving overall durability and service life, and possessing significant long-term economic value.

[0033] 4. This additive's molecular design is universal, making it widely applicable to various silane paste systems and highly compatible with mainstream topcoats such as epoxy, polyurethane, and acrylic. Its application requires no changes to existing processes, making it easy to promote in production and construction, and its industrialization prospects are clear. Attached Figure Description

[0034] Figure 1 This is a diagram showing the coating effect of the concrete protective coating system in Example 3-1; Figure 2 This is a diagram showing the coating effect of the concrete protective coating system in Comparative Example 3-3. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0036] Example 1: Preparation of multifunctional additives Example 1-1: A multifunctional additive, the preparation method of which is as follows: S1. Under nitrogen protection, add 50g toluene, 310g hydrogen-containing polysiloxane, and 90g allyl polyether to a 1000mL four-necked flask. Start stirring and heat to 80℃. After the system temperature stabilizes, add Karstedt catalyst (5ppm based on the total mass of polyether and hydrogen-containing siloxane), and continue stirring. After observing the system change from turbid to clear, continue the reaction at this temperature for 30min. The allyl polyether is an allyl hydroxyl-terminated polyether (weight average molecular weight 300, PO / EO=1).

[0037] S2. Add 81g of organosilicon monomer to the reaction system of step S1, and continue the reaction at 80℃ for 1h. After the reaction is completed, place the system in a rotary evaporator and remove toluene solvent and small molecules under a vacuum of 0.09MPa and a temperature of 120℃ to obtain a multifunctional auxiliary agent of pale yellow transparent viscous liquid, denoted as A-1; the organosilicon monomer is vinyltrimethoxysilane (A171).

[0038] The preparation method of hydrogen-containing polysiloxane is as follows: Under nitrogen protection, 250g of octamethylcyclotetrasiloxane, 75g of hydrogen-containing silicone oil (hydrogen content 1.2%), and 10g of hexamethyldisiloxane are added sequentially to a 500mL four-necked flask. Mechanical stirring is started at a speed of 200r / min, and the temperature is slowly increased to 70℃. After the system temperature stabilizes, 1.5g of p-toluenesulfonic acid is slowly added dropwise. After the addition is complete, the reaction is maintained at 70℃ for 8h. After the reaction is completed, the temperature is lowered to room temperature, and sodium bicarbonate powder is added to the system until the pH value reaches 7-8. After stirring for 30min, the solid impurities are removed by filtration. The filtrate is placed in a rotary evaporator and water and small molecule substances (unreacted raw materials, small molecule oligomers) are removed under a vacuum of 0.09MPa and a temperature of 110℃ to obtain 310g of hydrogen-containing polysiloxane.

[0039] Examples 1-2: The contents of Examples 1-2 are basically the same as those of Examples 1-1, except that: the allyl polyether is an allyl hydroxyl-terminated polyether (weight average molecular weight of 600, PO / EO=1), and its amount is 180g; the multifunctional additive prepared in this example is designated as A-2.

[0040] Examples 1-3: The contents of Examples 1-3 are basically the same as those of Examples 1-1, except that: the allyl polyether is an allyl hydroxyl-terminated polyether (weight average molecular weight of 900, PO / EO=1), and its amount is 270g; the multifunctional additive prepared in this example is designated as A-3.

[0041] Examples 1-4: The contents of Examples 1-4 are basically the same as those of Examples 1-1, except that: the allyl polyether is an allyl hydroxyl-terminated polyether (weight average molecular weight of 1200, PO / EO=1), and its amount is 360g; the multifunctional additive prepared in this example is designated as A-4.

[0042] Examples 1-5: The contents of Examples 1-5 are basically the same as those of Examples 1-1, except that: the allyl polyether is an allyl epoxy-terminated polyether (weight average molecular weight of 300, PO / EO=1); the multifunctional additive prepared in this example is designated as A-5.

[0043] Examples 1-6: The contents of Examples 1-6 are basically the same as those of Examples 1-1, except that: the allyl polyether is an allyl amino-terminated polyether (weight average molecular weight of 300, PO / EO=1); the multifunctional additive prepared in this example is designated as A-6.

[0044] Examples 1-7: The contents of Examples 1-7 are basically the same as those of Examples 1-1, except that: the organosilicon monomer is vinyltriisopropoxysilane (A173), and the amount used is 116g; the multifunctional additive prepared in this example is designated as A-7.

[0045] Examples 1-8: The contents of Examples 1-8 are basically the same as those of Examples 1-1, except that: the organosilicon monomer is methacryloxypropyltrimethoxysilane (KH570), and the amount used is 124g; the multifunctional additive prepared in this example is designated as A-8.

[0046] Comparative Example 1-1: No silicone monomer added A multifunctional additive, the preparation method of which is as follows: Under nitrogen protection, 50 g of toluene, 310 g of hydrogen-containing polysiloxane, and 90 g of allyl hydroxyl-terminated polyether (weight average molecular weight 300, PO / EO=1) were added to a 1000 mL four-necked flask. Stirring was started and the temperature was raised to 80 °C. After the system temperature stabilized, Karstedt catalyst (5 ppm based on the total mass of the polyether and hydrogen-containing polysiloxane) was added, and the reaction was continued with stirring. After observing the system change from turbid to clear, the reaction was maintained at this temperature for another 30 min. After the reaction was complete, the system was placed in a rotary evaporator, and toluene solvent and small molecules were removed under a vacuum of 0.09 MPa and a temperature of 120 °C to obtain a pale yellow, transparent, viscous liquid multifunctional additive, denoted as A-9.

[0047] The preparation method of the hydrogen-containing polysiloxane is the same as that in Examples 1-1.

[0048] Comparative Examples 1-2 without added allyl polyether A multifunctional additive, the preparation method of which is as follows: Under nitrogen protection, 50 g of toluene, 310 g of hydrogen-containing polysiloxane, and 81 g of vinyltrimethoxysilane were added to a 1000 mL four-necked flask. Stirring was started and the temperature was raised to 80 °C. After the system temperature stabilized, Karstedt catalyst (5 ppm based on the total mass of the polyether and hydrogen-containing siloxane) was added, and the reaction was continued with stirring for 60 min. After the reaction was complete, the system was placed in a rotary evaporator, and toluene solvent and small molecules were removed under a vacuum of 0.09 MPa and a temperature of 120 °C to obtain a pale yellow, transparent, viscous liquid multifunctional additive, denoted as A-10.

[0049] The preparation method of the hydrogen-containing polysiloxane is the same as that in Examples 1-1.

[0050] The molecular weight of the multifunctional additives prepared in Examples 1-1 to 1-8, Comparative Examples 1-1 and 1-2 was determined by gel permeation chromatography, and the results are shown in Table 1.

[0051] Table 1 Physicochemical parameters of multifunctional additives

[0052] Example 2: Preparation of silane paste Example 2-1: A silane paste comprising the following raw materials in weight percentages: 3% emulsifier, 80% alkoxysilane, 1% multifunctional additive, 0.8% thickener, 14% water, 0.6% preservative, and 0.6% bactericide. The emulsifier is fatty alcohol polyoxyethylene ether AEO-9, the alkoxysilane is isooctyltriethoxysilane, the multifunctional additive is A-1, the thickener is a polyurethane thickener, the water is deionized water, the preservative is isothiazolinone preservative, and the bactericide is benzalkonium chloride bactericide.

[0053] The specific steps for preparing the above-mentioned silane paste are as follows: Add the prescribed amount of deionized water to the mixing vessel, start stirring at 150 rpm, add the emulsifier and continue stirring until a uniform and transparent aqueous solution is formed. Increase the stirring speed to 800 rpm, and slowly add alkoxysilane dropwise to the aqueous solution at a rate controlled at 30-40 minutes. After the addition is complete, continue stirring for 20 minutes to form a preliminary emulsion system. Then reduce the stirring speed to 300 rpm, and add the prescribed amounts of multifunctional additive, thickener, preservative, and bactericide in sequence, and continue stirring for 30 minutes to obtain a uniform, fine, and particle-free white paste, which is silane paste B-1.

[0054] Example 2-2: The content of Example 2-2 is basically the same as that of Example 2-1, except that the multifunctional auxiliary agent A-1 described in Example 2-1 is replaced with A-2, thus obtaining silane paste B-2.

[0055] Examples 2-3: The contents of Examples 2-3 are basically the same as those of Example 2-1, except that the multifunctional additive A-1 described in Example 2-1 is replaced with A-3, thus obtaining silane paste B-3.

[0056] Examples 2-4: The contents of Examples 2-4 are basically the same as those of Example 2-1, except that the multifunctional additive A-1 described in Example 2-1 is replaced with A-4, thus obtaining silane paste B-4.

[0057] Examples 2-5: The contents of Examples 2-5 are basically the same as those of Example 2-1, except that the multifunctional additive A-1 described in Example 2-1 is replaced with A-5, thus obtaining silane paste B-5.

[0058] Examples 2-6: The contents of Examples 2-6 are basically the same as those of Example 2-1, except that the multifunctional additive A-1 described in Example 2-1 is replaced with A-6, thus obtaining silane paste B-6.

[0059] Examples 2-7: The contents of Examples 2-7 are basically the same as those of Example 2-1, except that the multifunctional additive A-1 described in Example 2-1 is replaced with A-7, thus obtaining silane paste B-7.

[0060] Examples 2-8: The contents of Examples 2-8 are basically the same as those of Example 2-1, except that the multifunctional additive A-1 described in Example 2-1 is replaced with A-8, thus obtaining silane paste B-8.

[0061] Comparative Example 2-1: The content of Comparative Example 2-1 is basically the same as that of Example 2-1, except that the multifunctional additive A-1 described in Example 2-1 is replaced with A-9, thus obtaining silane paste B-9.

[0062] Comparative Example 2-2: The content of Comparative Example 2-2 is basically the same as that of Example 2-1, except that the multifunctional additive A-1 described in Example 2-1 is replaced with A-10, thus obtaining silane paste B-10.

[0063] Comparative Examples 2-3: The contents of Comparative Examples 2-3 are basically the same as those of Example 2-1, except that no multifunctional additives are added, thus obtaining silane paste B-11.

[0064] The stability of the silane pastes prepared in Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-3 were tested, and the specific test methods are as follows: 1) Storage stability: The silane paste was sealed and placed at room temperature for 6 months, and the layering, oil floating and precipitation of the silane paste were observed.

[0065] 2) Mechanical stability: Place the silane paste in a centrifuge tube and centrifuge at 8000 r / min for 20 min. Observe whether stratification occurs.

[0066] 3) Thermal storage stability: Place the silane paste in a constant temperature chamber at 50℃ for 14 days and observe its layering, oil floating and precipitation.

[0067] The stability of the silane pastes prepared in Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-3 was tested, and the test results are shown in Table 2.

[0068] Table 2 Stability Test of Silane Paste

[0069] As shown in Table 2, the silane pastes B-1 to B-8 prepared using the multifunctional additives A-1 to A-8 of this invention exhibited excellent stability under conditions of 6 months of storage at room temperature, centrifugation at 8000 r / min for 20 min, and heat storage at 50℃ for 14 days. Their appearance remained consistently white paste, without layering, oil separation, or significant changes. When using the multifunctional additive A-10 without polyether segments, the prepared paste B-10 showed trace water precipitation, but the paste state was not disrupted; similarly, the comparative example B-11, without any additives, also showed trace water precipitation. This indicates that the polyether segments in the additives play an important role in maintaining the long-term hydration stability of the emulsion system. Notably, when using the multifunctional additive A-9 without silane end-capping, the stability test results of paste B-9 were identical to those in the examples, showing no significant changes. This suggests that while silane end-capping is crucial for subsequent application performance, the presence of polyethers plays a more dominant stabilizing role in the basic physical stability of the paste itself.

[0070] Example 3: Construction of a concrete protective coating system Example 3-1: The specific steps for constructing a concrete protective coating system are as follows: 1) Prepare C50 concrete test blocks with dimensions of 100mm×100mm×100mm. After standard curing for 28 days, use sandpaper to polish the surface of the test blocks to remove laitance and impurities, and clean the surface dust. 2) The silane paste B-1 prepared in Example 2-1 was applied to the surface of a concrete test block by brushing, with a coating amount of 250 g / m². 2 This forms a silane paste layer; 3) After 1 day, apply aliphatic polyurethane paint (dry film thickness 60μm) by spraying and cure for 7 days to obtain a complete concrete protective coating system.

[0071] Example 3-2: The content of Example 3-2 is basically the same as that of Example 3-1, except that the silane paste B-1 described in Example 3-1 is replaced with B-2.

[0072] Example 3-3: The content of Example 3-3 is basically the same as that of Example 3-1, except that the silane paste B-1 described in Example 3-1 is replaced with B-3.

[0073] Examples 3-4: The content of Example 3-2 is basically the same as that of Example 3-1, except that the silane paste B-1 described in Example 3-1 is replaced with B-4.

[0074] Examples 3-5: The contents of Examples 3-5 are basically the same as those of Example 3-1, except that the silane paste B-1 described in Example 3-1 is replaced with B-5, and the aliphatic polyurethane topcoat is replaced with epoxy resin paint.

[0075] Examples 3-6: Examples 3-6 are basically the same as those in Example 3-1, except that the silane paste B-1 described in Example 3-1 is replaced with B-6, and the aliphatic polyurethane topcoat is replaced with acrylic paint.

[0076] Examples 3-7: The contents of Examples 3-7 are basically the same as those of Example 3-1, except that the silane paste B-1 described in Example 3-1 is replaced with B-7.

[0077] Examples 3-8: The content of Example 3-2 is basically the same as that of Example 3-1, except that the silane paste B-1 described in Example 3-1 is replaced with B-8.

[0078] Comparative Example 3-1: The content of Comparative Example 3-1 is basically the same as that of Example 3-1, except that the silane paste B-1 described in Example 3-1 is replaced with B-9.

[0079] Comparative Example 3-2: The content of Comparative Example 3-2 is basically the same as that of Example 3-1, except that the silane paste B-1 described in Example 3-1 is replaced with B-10.

[0080] Comparative Example 3-3: The content of Comparative Example 3-3 is basically the same as that of Example 3-1, except that the silane paste B-1 described in Example 3-1 is replaced with B-11.

[0081] Comparative Examples 3-4: The contents of Comparative Examples 3-4 are basically the same as those of Example 3-1, except that the aliphatic polyurethane topcoat described in Example 3-1 is replaced with epoxy resin paint.

[0082] Comparative Examples 3-5: The contents of Comparative Examples 3-5 are basically the same as those of Example 3-1, except that the aliphatic polyurethane topcoat described in Example 3-1 is replaced with acrylic paint.

[0083] Blank example: A method for preparing a concrete test block is as follows: C50 concrete test blocks with dimensions of 100mm×100mm×100mm were prepared. After standard curing for 28 days, the surface of the test blocks was sanded to remove laitance and impurities, and the surface dust was cleaned.

[0084] Performance tests were conducted on Examples 3-1 to 3-8 and Comparative Examples 3-1 to 3-5, and the specific test methods are as follows: a. Observation of oil shrinkage defects After the protective paint layer is applied, surface defects of the coating are observed with the naked eye.

[0085] b. Interlayer adhesion test According to GB / T 5210-2006 "Paints and Varnishes Pull-off Test", the adhesion between the silane paste layer and the paint layer was tested using a pull-off tester.

[0086] c. Aging resistance test According to GB / T 1865-2009 "Artificial Climate Aging and Artificial Radiation Exposure of Paints and Varnishes", the coating system was subjected to a 1000-hour accelerated artificial aging test to test the appearance and interlayer adhesion of the coating after aging.

[0087] d. Concrete chloride ion penetration resistance test According to GB / T 50082-2009 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete", the concrete specimens coated with the protective coating system were tested by the electrical flux method.

[0088] Performance tests were conducted on Examples 3-1 to 3-8 and Comparative Examples 3-1 to 3-5, and the test results are shown in Table 3.

[0089] Table 3 Performance data of concrete protective coating system

[0090] Table 3 shows the impact of different silane paste base coat and topcoat combinations on the overall performance of the concrete protection system. Regarding coating defects, when all pastes prepared using additives A-1 to A-8 of this invention were used as base coats, subsequent spraying of aliphatic polyurethane paint, epoxy resin paint, or acrylic paint resulted in no oil shrinkage or other coating defects. However, when the base coat paste used A-10 (without polyether) or any additives, significant oil shrinkage was observed in the topcoat layer. Analysis suggests that the multifunctional additives in this invention, due to their unique amphiphilic structure, effectively reduce the interfacial tension between the silane paste layer and the organic topcoat, significantly improving interlayer wettability and thus completely eliminating oil shrinkage defects.

[0091] Regarding interlayer adhesion, the examples using the additives of this invention exhibited significantly higher initial and post-aging adhesion than the comparative examples. This is attributed to the fact that the silane-terminated groups in the additives, during the curing process of the paste, can undergo hydrolytic condensation with both the concrete substrate and the silane paste matrix. Furthermore, the active groups at their ends can chemically react with the active groups in the topcoat resin to form chemical bonds, greatly enhancing interlayer adhesion. While Comparative Example 3-1 showed acceptable paste stability, the lack of silane end-capping prevented it from forming strong chemical bonds with the topcoat, resulting in significantly lower adhesion compared to the examples.

[0092] Regarding the compatibility between the additives and the topcoat, the additives of this invention show good compatibility with various topcoats. However, although Comparative Examples 3-4 and 3-5 have no coating defects, their adhesion and aging resistance are far lower than those of the examples matched with polyurethane topcoats. This is mainly because the compatibility between the selected topcoat and the active groups of the additives is not ideal. When constructing the coating system, it is necessary to comprehensively consider whether the active groups of the additives and the topcoat can undergo cross-linking reactions. In terms of aging resistance, the coatings of the examples generally have a high adhesion retention rate after aging, especially the system matched with polyurethane, which shows a small decrease in adhesion and excellent appearance rating, indicating that the chemically bonded interface has excellent durability.

[0093] Regarding resistance to chloride ion penetration, the electrical flux values ​​of all test blocks coated with protective coatings were between 280C and 317C, far lower than the 3763.8C of the blank example, proving that the protective system can effectively perform its basic functions.

[0094] Figure 1 This is a diagram showing the coating effect of the concrete protective coating system in Example 3-1; Figure 2 This is a diagram illustrating the coating effect of the concrete protective coating system in Comparative Example 3-3. (Source: [Insert Source Here]) Figure 1 and Figure 2 As can be seen, when the topcoat was sprayed onto the silane paste layer in Comparative Example 3-3, significant oil shrinkage appeared on the coating surface, manifested as densely distributed dot-like or crater-like pits. The continuity of the coating was disrupted, and the overall appearance was uneven, making it difficult to meet the decorative requirements of the protective coating. In contrast, when the topcoat of Example 3-1, with the addition of the multifunctional additive, was applied, the coating exhibited excellent leveling properties, a smooth, uniform, and continuous surface, and no visible pinhole defects, demonstrating good appearance quality and application adaptability. The above comparative results show that the multifunctional additive provided by this invention, with its unique molecular structure, can effectively homogenize interfacial tension, eliminating the film shrinkage force caused by surface energy differences at the source, thereby completely solving the long-standing oil shrinkage problem in composite protective systems.

[0095] Example 4: The specific steps for constructing a concrete protective coating system are as follows: 1) Prepare C50 concrete test blocks with dimensions of 100mm×100mm×100mm. After standard curing for 28 days, use sandpaper to polish the surface of the test blocks to remove laitance and impurities, and clean the surface dust. 2) The silane paste B-5 prepared in Examples 2-5 was applied to the surface of concrete test blocks by brushing, with a coating amount of 250 g / m². 2 This forms a silane paste layer; 3) After 1 day, apply epoxy resin paint (dry film thickness 40μm) by spraying, and then apply aliphatic polyurethane topcoat (dry film thickness 60μm) after 1 day. Cure for 7 days to obtain a complete concrete protective coating system.

[0096] The performance of the concrete protective coating system in Example 4 was tested, and the test results are shown in Table 4.

[0097] Table 4 Application Performance Data of Example 4

[0098] As can be seen from the test data in Table 4, in terms of eliminating oil shrinkage defects, neither Example 4 (composite coating system) nor Examples 3-5 (single-layer epoxy system) showed oil shrinkage defects during the coating process. This result is in stark contrast to the aforementioned Comparative Example 3-3 (without additives), which fully demonstrates the key role of the multifunctional additive B-5 in silane paste.

[0099] Regarding interlayer adhesion, Example 4 achieved 7.8 MPa, and Examples 3-5 achieved 7.9 MPa, both of which are at a high level. This indicates that, regardless of whether it is a composite coating system or a single-layer epoxy system, excellent chemical bonds are formed between the silane paste layer and the epoxy paint, fully verifying the high reactivity compatibility between the active end groups of the additives and the epoxy system.

[0100] The aging resistance test results revealed the unique advantages of the composite protective system. After aging, Example 4 achieved an appearance rating of Grade 1, with adhesion remaining at 7.4 MPa, representing an adhesion retention rate of 94.9% compared to before aging. In contrast, Examples 3-5 achieved an appearance rating of Grade 3 after aging, with adhesion dropping to 4.0 MPa, a decrease of 49.4%. This stark contrast clearly demonstrates that Example 4, by introducing aliphatic polyurethane topcoat with excellent weather resistance as the surface layer, effectively protected the inner epoxy primer, enabling the entire system to maintain extremely high adhesion and a good appearance even after aging, truly achieving the design goal of comprehensive internal and external protection and long-lasting protection. In comparison, while single-layer epoxy systems have excellent initial adhesion, the aromatic ether bonds contained in the epoxy resin are prone to photo-oxidative degradation under long-term ultraviolet radiation, leading to surface deterioration and a significant decrease in interlayer adhesion.

[0101] Regarding resistance to chloride ion penetration, the electrical flux of Example 4 was 263.2 C, and that of Examples 3-5 was 280.3 C, both of which were much lower than that of unprotected concrete.

[0102] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Those skilled in the art can modify or make equivalent substitutions to the technical solutions of the present invention based on the concept of the present invention, without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A multifunctional additive, characterized in that, The general structural formula of the multifunctional additive is: Wherein, R is any one of H, CH2CH(O)CH2, NH2, COOH, SO3H, and PO3H2; R 1 R 2 R 3 R 4 Each of the following is an alkyl group from C1 to C4; a is an integer from 1 to 50; b is an integer from 1 to 200; c is an integer from 0 to 100; d is an integer from 0 to 50; c+d≥1; x is an integer from 0 to 30; y is an integer from 1 to 40; m is an integer from 0 to 2; n is an integer from 0 to 2; EO is ethylene oxide; PO is propylene oxide.

2. The multifunctional additive according to claim 1, characterized in that, The weight-average molecular weight of the multifunctional additive is 5000–15000 g / mol.

3. The method for preparing the multifunctional adjuvant according to claim 1 or 2, characterized in that, Includes the following steps: Under an inert gas atmosphere, the solvent, hydrogen-containing polysiloxane, and allyl polyether are sequentially added to the reactor, stirred, and heated to 70–90°C. The Karstedt catalyst is then added, and the reaction is stirred until the reaction system changes from turbid to clear. The reaction is then maintained at this temperature for 0.5–1 hour. Then, an organosilicon monomer is added to the reaction system, and the reaction continues for another 0.5–1 hour. After the reaction is complete, the solvent in the reaction system is removed to obtain the multifunctional additive.

4. The method for preparing the multifunctional additive according to claim 3, characterized in that, The structural formula of the allyl polyether is: Wherein, R is any one of H, CH2CH(O)CH2, NH2, COOH, SO3H, PO3H2, x is an integer from 0 to 30, and y is an integer from 1 to 40; The structural formula of the hydrogen-containing polysiloxane is: Where z is an integer from 2 to 200, and b is an integer from 1 to 200.

5. The method for preparing the multifunctional additive according to claim 3 or 4, characterized in that, The solvent is any one of toluene, xylene, isopropanol, and butanol; the weight-average molecular weight of the allyl polyether is 300–1200 g / mol; the organosilicon monomer is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, and 3-methacryloyloxypropyltriethoxysilane.

6. A silane paste, characterized in that, Includes the multifunctional adjuvant as described in claim 1 or 2.

7. The silane paste according to claim 6, characterized in that, It is mainly composed of the following raw materials by weight percentage: Emulsifier 1%–5%, alkoxysilane 75%–82%, multifunctional additive 0.1%–2%, thickener 0.5%–1%, water 15%–20%, preservative 0.5%–1%, bactericide 0.5%–1%.

8. The application of the silane paste according to claim 6 or 7 in concrete protection or concrete protective coating systems.

9. A method for constructing a concrete protective coating system, characterized in that, Includes the following steps: The silane paste described in claim 6 or 7 is applied to the surface of a concrete substrate to form a silane paste layer. After an interval of 1 to 7 days, a protective paint is applied to the surface of the silane paste layer to obtain a concrete protective coating system.

10. The method for constructing the concrete protective coating system according to claim 9, characterized in that, The protective paint is at least one of epoxy resin paint, polyurethane paint, acrylic paint, and fluorocarbon paint.

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