Nano-silica hydrophobicity-enhanced lotus effect caulking agent and preparation method thereof

Abstract

The invention relates to the field of building materials, and particularly discloses a nanosilicon dioxide hydrophobicity enhanced lotus effect joint mixture and a preparation method thereof. According to the joint mixture, the white cement is used as a cementing material, the graded quartz sand powder is used as a framework, the compactness and strength are improved through the composite kaolin and the composite nano-calcium, a double-hydrophobic network is constructed through the hydrophobic rubber powder and the nano-silicon dioxide, and the nano-zinc provides an antibacterial function. Uniform dispersion of nano components is realized through a three-stage mixing process, a self-cleaning surface with low water absorption and high contact angle is formed after the product is cured, and the product has high strength and alkali burnout resistance and is suitable for filling ceramic tile gaps.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, and in particular to a nano-silicon dioxide hydrophobic enhanced lotus leaf effect caulking agent and a preparation method thereof. Background Art

[0002] Traditional cement-based caulking agents are prone to efflorescence and poor stain resistance due to their high water absorption. While adding latex powder can improve flexibility, it is difficult to balance the contradiction between low water absorption and high strength. In existing technologies, single hydrophobic agents (such as silicone) or nanomaterials (such as SiO2) cannot simultaneously achieve a dense structure, low water absorption, and long-term antibacterial properties due to uneven dispersion or single functions. Some patents attempt to compound antimicrobial agents (such as nano-magnesium oxide / chitosan), but they do not solve the problem of nano-agglomeration and ignore the key impact of graded aggregate on shrinkage and strength.

[0003] The present invention addresses these shortcomings by synergizing hydrophobic adhesive powder and nano-SiO2 to create a dual hydrophobic barrier. This, combined with the dense packing of graded quartz sand, the consumption of free Ca(OH)2 by composite nano-calcium to inhibit efflorescence, and the sustained release of nano-zinc for antibacterial effects, achieves a multifunctional all-in-one solution. This three-stage mixing process ensures uniform dispersion of the nano-components, overcoming the performance bottleneck of traditional caulking agents. Summary of the Invention

[0004] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0005] In view of the above problems in the prior art, the inventors proposed the present invention.

[0006] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a nano-silica hydrophobic enhanced lotus leaf effect caulking agent and a preparation method thereof.

[0007] To solve the above technical problems, the present invention provides the following technical solution: a nano-silica hydrophobic enhanced lotus leaf effect caulking agent, comprising the following components in parts by weight:

[0008] 30-40 parts of white cement, 40-60 parts of graded quartz sand powder, 2-20 parts of composite kaolin, 5-8 parts of composite nano-calcium, 0.2-10 parts of nano-zinc, 1-6 parts of hydrophobic redispersible latex powder, 0.2-3 parts of nano-silicon dioxide, 0.1-0.6 parts of hydroxypropyl methylcellulose, 0.2-1 parts of thixotropic lubricant, 0.1-0.8 parts of polycarboxylate water reducer, and 0.3-3 parts of silicone defoamer;

[0009] The graded quartz sand powder is compounded from 120-mesh, 400-mesh and 800-mesh quartz sands, and the nano-silica and the hydrophobic redispersible latex powder synergistically form a double hydrophobic network, so that after the caulking agent is cured, the surface contact angle is ≥120 degrees and the water absorption rate is ≤1.0g in 30 minutes, forming a self-cleaning layer with a lotus leaf effect.

[0010] As a preferred embodiment of the nano-silica hydrophobically enhanced lotus effect caulking agent described in the present invention, the mass ratio of 120 mesh, 400 mesh and 800 mesh quartz sand in the graded quartz sand powder is (3-5):(2-4):(1-3), and the graded bulk porosity is ≤18%.

[0011] As a preferred embodiment of the hydrophobic enhanced lotus leaf effect nano-silica caulking agent of the present invention, the nano-silica is gas-phase nano-SiO2 with a specific surface area of ​​≥200m 2 / g, particle size is 10-50nm;

[0012] The particle size of the composite nano-calcium is 50-100 nm, and the particle size of the nano-zinc is 20-50 nm.

[0013] As a preferred embodiment of the nano-silica hydrophobically enhanced lotus effect caulking agent of the present invention, the hydrophobic redispersible latex powder is ethylene-vinyl acetate copolymer powder or acrylate powder, and its glass transition temperature is ≤-10°C.

[0014] As a preferred embodiment of the nano-silica hydrophobically enhanced lotus effect caulking agent of the present invention, the composite kaolin is calcined kaolin with an activity index ≥90%, and participates in the volcanic ash reaction with the composite nano-calcium to generate CSH gel to fill microcracks.

[0015] A preferred method for preparing a nano-silica hydrophobically enhanced lotus leaf effect caulking agent comprises the following steps:

[0016] (1) Add white cement, graded quartz sand powder, composite kaolin, composite nano calcium, and nano zinc into a mixer and mix at a low speed of 200-400 rpm for 5-10 minutes until uniform;

[0017] (2) Add hydrophobic redispersible latex powder, hydroxypropyl methylcellulose, thixotropic lubricant, polycarboxylic acid water reducer, and silicone defoamer, and mix at a medium speed of 600-800 rpm for 8-15 minutes;

[0018] (3) Add nano-silicon dioxide, mix at a high speed of 1000-1200 rpm for 3-5 minutes, and then pass through an 80-mesh sieve to control the fineness to ≤0.1 mm.

[0019] As a preferred embodiment of the method for preparing a nano-silica hydrophobically enhanced lotus effect caulking agent according to the present invention, the high-speed mixing in step (3) is performed by adding materials in stages, first adding 50% of the nano-silica and mixing for 2 minutes, and then adding the remaining 50% and continuing to mix until uniform.

[0020] As a preferred solution of the method for preparing the nano-silica hydrophobically enhanced lotus effect caulking agent of the present invention, the mixing process of steps (1) and (2) is carried out in an environment with a humidity of ≤40%.

[0021] As a preferred application scheme of the nano-silica hydrophobically enhanced lotus leaf effect caulking agent described in the present invention, after being used to fill the gaps between tiles, a hardened body with a compressive strength ≥30 MPa, a flexural strength ≥8.0 MPa, and a shrinkage rate ≤0.10% is formed, and the self-cleaning layer has a soy sauce and coffee stain resistance level reaching GB / T3810.14-2016 standard level 5.

[0022] As a preferred application of the nano-silica hydrophobically enhanced lotus leaf effect caulking agent of the present invention, when the caulking agent is applied to a 3-10 mm wide seam, the thixotropic lubricant and HPMC synergistically provide anti-sagging properties, and the sag degree is ≤1 mm.

[0023] Beneficial effects of the present invention: The dual hydrophobic mechanism of the sealant and the synergy of multiple components: the hydrophobic glue powder forms a film to close the capillaries, and the nano-SiO2 forms a micro-nano rough structure on the pore surface, which synergistically reduces the water absorption rate to ≤1.0g and the contact angle ≥120°, realizing the lotus leaf effect self-cleaning; the composite nano-calcium and kaolin consume Ca(OH)2 through volcanic ash reaction, blocking the alkali efflux path; the graded quartz sand achieves the densest stacking, improving the compressive strength and wear resistance.

[0024] In addition, nano zinc slowly releases Zn 2+ Providing long-lasting antibacterial properties, thixotropic lubricants and HPMC optimize anti-sagging properties for wide-joint construction. The product has a grade 5 stain resistance, an antibacterial rate of 99.2%, and outstanding environmental performance, meeting the needs of high-end building materials. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0026] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it constitute a separate or selective embodiment that is mutually exclusive with other embodiments.

[0028] Example 1

[0029] This embodiment provides a nano-silicon dioxide hydrophobic enhanced lotus leaf effect caulking agent and a preparation method thereof.

[0030] Formula (parts by weight):

[0031] Specific cementitious materials and skeleton: 38 parts of white cement (P.W52.5, produced by Hebei Jinyu); 52 parts of graded quartz sand powder (120 mesh: 400 mesh: 800 mesh = 4:3:2, produced by Guangdong Sibelco).

[0032] The preferred active components are: 12 parts of composite kaolin (calcined type, active index 95%, produced by Longyan Kaolin Company); 6.5 parts of composite nano calcium (particle size 80 nm, produced by Shanghai Aladdin); and 1.8 parts of nano zinc (particle size 30 nm, produced by Jiangsu Xianfeng Nano).

[0033] Further functional additives: 3.5 parts of hydrophobic EVA powder (Wacker 5044N, glass transition temperature -15°C); fumed nano-SiO2 (Evonik AEROSIL 200, specific surface area 200m 2 / g) 1.2 parts; HPMC (Dow K15M) 0.35 parts; thixotropic lubricant (modified bentonite, produced by Zhejiang Fenghong) 0.6 parts; polycarboxylate water reducer (BASF 2651F) 0.45 parts; silicone defoaming agent (Digo 810) 0.6 parts.

[0034] Preparation method:

[0035] (1) In an environment with a humidity of ≤40%, white cement, graded quartz sand powder, composite kaolin, composite nano-calcium, and nano-zinc were put into a coulter mixer and mixed at a low speed of 300 rpm for 8 minutes until uniform;

[0036] (2) Add EVA rubber powder, HPMC, thixotropic lubricant, water reducer, and defoamer, and mix at a medium speed of 700 rpm for 12 minutes;

[0037] (3) As an embodiment, nano-SiO2 is added in two batches: first, 0.6 parts are added and mixed at a high speed of 1100 rpm for 2 minutes, and then the remaining 0.6 parts are added and mixed for 3 minutes, and the fineness is controlled to be ≤0.1 mm through an 80-mesh sieve.

[0038] Performance testing:

[0039] Physical properties: water absorption rate of 0.75g in 30 minutes; compressive strength of 34.2MPa and flexural strength of 8.7MPa in 28 days; shrinkage rate of 0.09%; wear resistance of 850mg (rotational friction of 1000 revolutions).

[0040] Functional properties: contact angle 128°; stain resistance (soy sauce wipe) level 5; antibacterial rate (Escherichia coli) 99.3%; anti-alkalinity (56d wet heat test) no visible white spots.

[0041] Construction performance: 3mm wide seam sag is 0.8mm.

[0042] Example 2

[0043] This embodiment provides a nano-silicon dioxide hydrophobic enhanced lotus leaf effect caulking agent and a preparation method thereof.

[0044] Recipe Adjustment:

[0045] Specific hydrophobic enhancement: nano-SiO2 increased to 2.5 parts (added in two batches, 1.25 parts each), hydrophobic EVA powder increased to 5 parts;

[0046] The preferred gradation optimization: the quartz sand powder is adjusted to 120 mesh: 400 mesh: 800 mesh = 3:4:3, and the bulk porosity is reduced to 16.5%.

[0047] The preparation method is the same as that of Example 1.

[0048] Performance improvement and mechanism analysis:

[0049] Hydrophobic performance: water absorption rate is reduced to 0.42g, and the contact angle is increased to 137°;

[0050] Strength and density: compressive strength 36.5MPa (gradation optimization reduces porosity); wear resistance increased to 780mg.

[0051] Stain resistance verification: coffee stain resistance level 5, confirming the lotus leaf effect self-cleaning function.

[0052] Example 3

[0053] This embodiment provides a nano-silicon dioxide hydrophobic enhanced lotus leaf effect caulking agent and a preparation method thereof.

[0054] Recipe Adjustment:

[0055] Specific construction adaptability: the quartz sand powder gradation is changed to 120 mesh: 400 mesh = 7:3 (800 mesh sand is eliminated to improve the support of the wide seam skeleton);

[0056] Further rheological optimization: thixotropic lubricant increased to 0.8 parts, HPMC increased to 0.5 parts.

[0057] Preparation method same as Example 1.

[0058] Effect verification:

[0059] Workability: no sagging (sagging degree 0.5mm) in 10mm wide gap, smooth extrusion;

[0060] Physical properties: shrinkage 0.07% (coarse aggregate reduces water evaporation); compressive strength 30.8MPa;

[0061] Durability: strength loss rate ≤5% after 50 freeze-thaw cycles (low water absorption inhibits ice expansion).

[0062] The core breakthrough of the technology is to build a double hydrophobic network inside the jointing agent through the molecular level synergy of hydrophobic redispersed latex powder and fumed nano-SiO2. Its mechanism of action contains two key aspects: first, the hydrophobic powder migrates to the inner wall of the capillary pore during cement hydration, covering the pore surface through film formation, significantly reducing the surface energy of the matrix; second, nano-SiO2 forms a micro-nano scale rough structure inside the pore due to its ultra-high specific surface area (≥200m 2 / g) and surface silicon hydroxyl activity. This micro-nano double structure breaks through the 120° critical value of water contact angle, realizing the super-hydrophobic state of the lotus leaf effect. It is worth noting that this double network is not simply superimposed - the organic long chain of the powder and nano-SiO2 form an interpenetrating structure through physical adsorption and hydrogen bonding, significantly improving hydrophobic durability. In Example 2, when the amount of nano-SiO2 is increased to 2.5 parts, the contact angle jumps to 137°, and this is due to the formation of a more dense hydrophobic film inside the pore by the increased nanoparticles;

[0063] The mechanical strength of the material is derived from the multi-scale densification design: on the macro level, the graded system of 120-800 mesh quartz sand (e.g. 4:3:2 ratio in Example 1) achieves the closest packing, compressing the porosity to below 18%, effectively blocking the water penetration path; on the micro level, calcined kaolin and composite nano-calcium react through the pozzolanic reaction, efficiently consuming the free Ca(OH)2 in the cement hydration products. This process not only inhibits the formation of efflorescence sources, but more importantly generates C-S-H gel with a low calcium-silicon ratio, which has a higher degree of polymerization and can effectively fill micro-cracks.

[0064] From the perspective of material evolution, composite nano-calcium (50-100nm) reacts with calcium hydroxide to form an early strength framework due to its high reactivity, while kaolin (activity index ≥95%) continuously reacts in the middle and late stages, forming a "relay mechanism" for strength development. This time and space ordered reaction design enables the compressive strength to break through 30MPa while the shrinkage is suppressed within 0.10%, solving the contradiction between high strength and low shrinkage in traditional jointing agents;

[0065] Three-stage mixing process: In the first stage (200-400rpm), inorganic skeletons such as white cement and quartz sand are pre-mixed with composite nano-calcium / zinc, and mechanical force is used to peel off the soft agglomeration of nanoparticles; in the second stage (600-800rpm), organic modifiers are introduced to make the rubber powder molecular chains wrap the previously dispersed nanoparticles; in the third stage (1000-1200rpm), nano-SiO2 is sheared at high speed, and the characteristics of aerosol particles are used to embed it into the formed organic-inorganic interface.

[0066] It is particularly important to note that the staged addition of nano-SiO2 (e.g., two batches in Example 1) prevents local overheating that can lead to premature film formation of the rubber powder, ensuring precise positioning of the hydrophobic component within the pores. Maintaining a humidity of ≤40% significantly reduces the risk of prehydration of the composite nano-calcium and ensures the reactive efficiency of the active component.

[0067] In summary, this formulation maintains the environmental advantages of inorganic materials (nearly zero VOC emissions) while offering the ease of construction of polymer grouts. In particular, Example 3 demonstrates its adaptability to extrusion coating processes, providing a technical path for upgrading traditional grouts. Future developments could include developing derivatives such as medical antibacterial grouts by adjusting the nano-zinc loading and photocatalytic self-cleaning grouts by coupling with nano-TiO2, expanding the market for high-end building materials.

[0068] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A nano-silica hydrophobic enhanced lotus leaf effect caulking agent, characterized by: The following components are included by weight: 30-40 parts of white cement, 40-60 parts of graded quartz sand powder, 2-20 parts of composite kaolin, 5-8 parts of composite nano-calcium, 0.2-10 parts of nano-zinc, 1-6 parts of hydrophobic redispersible latex powder, 0.2-3 parts of nano-silicon dioxide, 0.1-0.6 parts of hydroxypropyl methylcellulose, 0.2-1 parts of thixotropic lubricant, 0.1-0.8 parts of polycarboxylate water reducer, and 0.3-3 parts of silicone defoamer; The graded quartz sand powder is compounded from 120-mesh, 400-mesh and 800-mesh quartz sands, and the nano-silica and the hydrophobic redispersible latex powder synergistically form a double hydrophobic network, so that after the caulking agent is cured, the surface contact angle is ≥120 degrees and the water absorption rate is ≤1.0g in 30 minutes, forming a self-cleaning layer with a lotus leaf effect.

2. The nano-silica hydrophobic enhanced lotus leaf effect caulking agent according to claim 1, characterized in that: The mass ratio of 120 mesh, 400 mesh and 800 mesh quartz sand in the graded quartz sand powder is (3-5):(2-4):(1-3), and the graded bulk porosity is ≤18%.

3. The nano-silica hydrophobic enhanced lotus leaf effect caulking agent according to claim 1, characterized in that: The nano-silicon dioxide is gas phase nano-SiO2 with a specific surface area of ​​≥200m 2 / g, particle size is 10-50nm; The particle size of the composite nano-calcium is 50-100 nm, and the particle size of the nano-zinc is 20-50 nm.

4. The nano-silica hydrophobic enhanced lotus leaf effect caulking agent according to claim 1, characterized in that: The hydrophobic redispersible latex powder is ethylene-vinyl acetate copolymer rubber powder or acrylic rubber powder, and its glass transition temperature is ≤-10°C.

5. The nano-silica hydrophobic enhanced lotus leaf effect caulking agent according to claim 1, characterized in that: The composite kaolin is calcined kaolin with an activity index of ≥90%, and participates in volcanic ash reaction with composite nano-calcium to generate CSH gel to fill micro cracks.

6. A method for preparing a nano-silica hydrophobically enhanced lotus effect caulking agent according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Add white cement, graded quartz sand powder, composite kaolin, composite nano calcium, and nano zinc into a mixer and mix at a low speed of 200-400 rpm for 5-10 minutes until uniform; (2) Add hydrophobic redispersible latex powder, hydroxypropyl methylcellulose, thixotropic lubricant, polycarboxylic acid water reducer, and silicone defoamer, and mix at a medium speed of 600-800 rpm for 8-15 minutes; (3) Add nano-silicon dioxide, mix at a high speed of 1000-1200 rpm for 3-5 minutes, and then pass through an 80-mesh sieve to control the fineness to ≤0.1 mm.

7. The nano-silica hydrophobic enhanced lotus leaf effect caulking agent and its preparation method as claimed in claim 6, characterized in that: In step (3), the high-speed mixing is performed by adding materials in stages. First, 50% of the nano-silicon dioxide is added and mixed for 2 minutes, and then the remaining 50% is added and mixed until uniform.

8. The nano-silica hydrophobic enhanced lotus leaf effect caulking agent and its preparation method as claimed in claim 6, characterized in that: The mixing process of steps (1) and (2) is carried out in an environment with a humidity of ≤40%.

9. The use of a nano-silicon dioxide hydrophobic enhanced lotus leaf effect caulking agent as claimed in claim 1, characterized in that: After being used to fill the gaps in tiles, it forms a hardened body with a compressive strength ≥30MPa, a flexural strength ≥8.0MPa, and a shrinkage rate ≤0.10%. The self-cleaning layer's stain resistance to soy sauce and coffee reaches level 5 of the GB / T3810.14-2016 standard.

10. The use of a nano-silicon dioxide hydrophobic enhanced lotus leaf effect caulking agent as claimed in claim 9, characterized in that: When the sealant is applied to a 3-10 mm wide seam, the thixotropic lubricant and HPMC cooperate to provide anti-sagging properties, with a sag degree of ≤1 mm.