CN115991942B - Weathering-proof material for surface of open-air masonry cultural relics and preparation method thereof - Google Patents

Abstract

The invention discloses a surface weather-proof material for open-air masonry relics and a preparation method thereof. The surface anti-weathering material comprises 0.05-5% of TiO which is uniformly mixed ₂ A base nanocomposite and 95% to 99.95% alcohol solvent, wherein the TiO ₂ The base nano composite material is partially fluorinated siloxane and nano TiO ₂ The percentage is mass percent. When the windproof material is used, the windproof material is uniformly coated on the surfaces of masonry relics of various types and different materials by spraying or brushing, and the multifunctional windproof layer is prepared after the solvent is completely volatilized. The invention endows the masonry relic with excellent hydrophobicity, photocatalytic antifouling and antibacterial properties, has good durability to keep a long-term wind-proof effect, and solves the problems of complex preparation process, poor antibacterial property, poor wear resistance and corrosion resistance and the like of the existing masonry relic super-hydrophobic wind-proof material, which are not suitable for large-scale production and application.

Description

Weathering-proof material for surface of open-air masonry cultural relics and preparation method thereof

Technical field

The invention belongs to the field of cultural relic protection materials and technology, and specifically relates to an open-air masonry cultural relic surface weatherproofing material and a preparation method thereof.

Background technique

Brick and stone cultural relics such as cliff carvings, grotto statues, ancient masonry buildings, and stone carvings have suffered long-term deterioration in the open air environment caused by natural environmental factors, biological factors, and human activities. The structure, material, and art contained in the cultural relics have The loss of value is severe. Research shows that surface weathering of masonry cultural relics is a physical, chemical and biological weathering caused by the deposition of acid rain, atmospheric pollutants, microbial spores, etc. Fundamentally, gaseous/liquid water, soluble salts, and microorganisms are responsible for causing surface weathering. key factors. Therefore, it is very urgent to develop anti-weathering materials with good compatibility, excellent hydrophobicity, antifouling and antibacterial effects for the protection of open-air masonry cultural relics.

In recent years, superhydrophobic materials with excellent hydrophobicity and self-cleaning functions have shown strong application potential in many fields such as cultural relic protection. Their excellent properties can protect the cultural relics from water damage and reduce the adhesion of microbial spores/bacterial cells. , and can clean the surface and maintain artistic features. Foreign cultural relic protection scholars Mosquera and Karapanagiotis (ACSAppl.Mater.Interfaces, 2020,12:19974; Construct.Build.Mater., 2022,320:126175), as well as domestic scholars Liu Shaojun, He Ling, Bai Xiaojuan, etc. (Prog.Org .Coat.,2021,151:106097; J.Clearn.Prod.,2022,381:134975) prepared a variety of superhydrophobic materials based on nanocomposites and polymer materials for use in stone sculptures of different materials, grotto statues and ancient buildings. The surface is weatherproof. The above-mentioned materials have outstanding hydrophobicity, and some also have certain photocatalytic effects, but they have not yet been applied and promoted on a large scale. The main reason is that key bottlenecks such as antibacterial properties, wear resistance, and corrosion resistance of the materials still need to be broken through.

At present, my country also has some patents involving super-hydrophobic weatherproof materials for masonry cultural relics. The Chinese patent number CN201010618653.8 discloses an inorganic-organic super-hydrophobic composite material for stone cultural relics and its preparation method. A super-hydrophobic weatherproof layer can be produced by dispersing nano-ZnO/SiO ₂ particles with a mass fraction of 0.2-4% and a particle size of 20-200 nm into the hydrophobic organic silicon liquid phase, and then coating them on the surface of the stone. The preparation process of this method is complicated. SiO ₂ nanoparticles need to be prepared first, then ZnO is coated on the SiO ₂ surface, and then ball milling and ultrasonic dispersion are used to disperse the nanoparticles in the organic solution. In addition, this material does not show its photocatalytic antifouling and antibacterial effects, and its function is relatively single.

The Chinese patent number CN202011039777.0 discloses a preparation method for a durable hydrophobic and photoaging-resistant stone cultural relic sealing coating. First, prepare fluorosilane-modified nano-TiO ₂ in isopropyl alcohol solution, then add it to the prepared mixed solution of polydimethylsiloxane and curing agent, and finally spray the above mixed solution on the surface of the stone cultural relics and place it on the surface of the stone cultural relics. Weatherproof coating can be obtained by curing at room temperature and vacuum environment. In this method, the sealing coating needs to be cured in a vacuum environment and is not suitable for use in open air environments.

The Chinese patent number CN201611072794.8 discloses a preparation method of organic nanocomposite protective materials for the protection of stone cultural relics composed of fluorocarbon emulsion film-forming substances, modified nanoparticles, additives and water. The preparation process of this method is complex and requires many types of raw materials. Moreover, the weatherproof layer prepared does not have antifouling or antibacterial effects and has a relatively single function.

The technical solutions provided by the above-mentioned documents and patents solve some problems of weather protection on the surface of masonry cultural relics, but factors such as complex material preparation process, single function, and poor durability limit its large-scale application and promotion.

Contents of the invention

In order to avoid the shortcomings of the prior art, the present invention proposes a nano-composite multifunctional material based on nano- _TiO2 and a preparation method thereof, which is used for weathering prevention of masonry cultural relics. The weathering prevention layer formed has good durability to maintain a long-term weathering prevention effect. The method provided by the present invention solves the problems of the existing super-hydrophobic weathering prevention materials for masonry cultural relics, such as complex preparation process, poor antibacterial property, poor wear resistance and corrosion resistance, and unsuitability for large-scale production and application.

According to one aspect of the present invention, a surface weathering-proof material for open-air masonry cultural relics is provided, wherein the surface weathering-proof material comprises a uniform mixture of 0.05% to 5% TiO2 _- based nanocomposite material and 95% to 99.95% solvent, wherein the _TiO2- based nanocomposite material is a reaction product of partially fluorinated siloxane and nano- _TiO2 , and the solvent is an alcohol solvent, wherein the percentages are mass percentages.

The TiO ₂ -based nanocomposite material is made by adding nano TiO ₂ to a dispersion with a mass fraction of 1% to 5% formed by dispersing partially fluorinated siloxane in an alcohol solvent (preferably isopropyl alcohol), and then stirring and It is produced by reaction under heating conditions, in which the molar ratio of partially fluorinated siloxane to nano-TiO ₂ is 1:1 to 1:2.

The partially fluorinated siloxane is prepared by reacting an aminoalkyl silane coupling agent with a molar ratio of 1:1 and a hexafluorooxypropane trimer.

The aminoalkyl silane coupling agent is one of the following structural formulas I(a), I(b) or a combination thereof, where R ₁ and R ₂ represent linear or branched alkane with 1 to 30 carbon atoms. group, taking into account factors such as cost, synthesis difficulty and reactivity, R ₁ and R ₃ are preferably methyl (-CH ₃ ) or ethyl (-C ₂ H ₅ ), and R ₂ is preferably propyl (-C ₃ H ₇ ), butyl (-C ₄ H ₉ ).

The structural formula of the hexafluorooxypropane trimer is as follows.

According to another aspect of the present invention, there is provided a method for preparing the above-mentioned weathering-proof material for the surface of an open-air masonry cultural relic, comprising the following steps:

(1) Preparation of partially fluorinated siloxane: Under inert atmosphere, solvent-free, room temperature conditions, measure the aminoalkyl silane coupling agent and hexafluorooxypropane trimer according to the molar ratio of 1:1, and stir thoroughly Mix, and after reaction, partially fluorinated siloxane is produced;

The aminoalkyl silane coupling agent is one or more of the formulas I(a) and I(b), and its structural formula is as follows, where R ₁ and R ₂ represent straight-chain or linear chains with 1 to 30 carbon atoms. For branched alkyl groups, considering factors such as cost, difficulty of synthesis, and reactivity, R ₁ and R ₃ are preferably methyl (-CH ₃ ) or ethyl (-C ₂ H ₅ ), and R ₂ is preferably propyl (- C ₃ H ₇ ), butyl (-C ₄ H ₉ ).

The structural formula of the hexafluorooxypropane trimer is as follows.

(2) Preparation of TiO _2- based nanocomposites: First, use HNO ₃ (2M) to pretreat anatase nano-TiO ₂ as described in (J.Appl.Polym.Sci., 2015, 132:42047) As described above; take an appropriate amount of the partially fluorinated siloxane prepared in step (1) and disperse it in an alcohol solvent (preferably isopropyl alcohol) to form a dispersion with a mass fraction of 1% to 5%, and then slowly add an appropriate amount under magnetic stirring. The treated nano-TiO ₂ has a molar ratio of partially fluorinated siloxane to nano-TiO ₂ of 1:1 to 1:2; the mixture is ultrasonically dispersed and then reacted under magnetic stirring and heating (40 to 60°C). That is, the TiO _2- based nanocomposite material is obtained.

(3) Preparation of weatherproof material: 0.05% to 5% of the TiO2 _- based nanocomposite material prepared in step (2) and 95% to 99.95% of a solvent are weighed in percentage by mass, and the mixture is stirred and mixed thoroughly, wherein the solvent is an alcohol solvent.

Preparation of multifunctional weatherproof layer: Apply the weatherproof material prepared as above evenly to the surface of masonry cultural relics of various types and materials through spraying or brushing equipment. The concentration of the weatherproof material used is preferably 0.01% to 10%, more preferably 0.05% to 5%, and the percentage is a mass percentage. After the solvent is completely evaporated, a multifunctional weatherproof layer is prepared.

The surface anti-weathering material proposed by the present invention endows masonry cultural relics with excellent hydrophobicity, photocatalytic antifouling and antibacterial properties, and has good durability to maintain long-term weathering effect, solving the problem of excessive existing masonry cultural relics. The preparation process of hydrophobic and weather-resistant materials is complex, their bacteriostatic properties are poor, and their wear and corrosion resistance are poor. They are not suitable for large-scale production and application.

Description of drawings

Figure 1 is a self-cleaning performance test chart of the weatherproof layer prepared according to Embodiment 1 of the present invention.

Figure 2 is a schematic diagram of the original micromorphology of the stone substrate surface (a), the surface micromorphology after anti-weathering layer treatment (b), and the water contact angle in Example 1 of the present invention.

Figure 3 is a photocatalytic antifouling performance test chart of the anti-weathering layer in Example 2 of the present invention.

Detailed ways

In order to understand the purpose, technical solutions and advantages of the present invention more clearly, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Unless otherwise specified, various raw materials in the present invention are commercially available products, or can be obtained according to general preparation methods in the field. The technical terms used in this article are the same as those commonly used in this field.

The invention provides a multifunctional weatherproof material and a preparation method thereof. The raw materials of the multifunctional weatherproof material include TiO2 _- based nanocomposite materials and solvents. Wherein, the _TiO2- based nanocomposite material is produced by the reaction of partially fluorinated siloxane and nanometer _TiO2 . Specific steps are as follows.

(1) Preparation of partially fluorinated siloxane: Under inert atmosphere, solvent-free, room temperature conditions, measure the aminoalkyl silane coupling agent and hexafluorooxypropane trimer according to the molar ratio of 1:1, and stir thoroughly Mix and react (the reaction time is preferably 6 to 8 hours) to obtain partially fluorinated siloxane.

The aminoalkylsilane coupling agent is one or more of formulas I(a) and I(b), and its structural formula is as follows, wherein R ₁ and R ₂ represent straight-chain or branched alkyl groups with 1 to 30 carbon atoms. Considering factors such as cost, synthesis difficulty and reaction activity, R ₁ and R ₃ are preferably methyl (-CH ₃ ) and ethyl (-C ₂ H ₅ ), and R ₂ is preferably propyl (-C ₃ H ₇ ) and butyl (-C ₄ H ₉ ).

The structural formula of the hexafluorooxypropane trimer is as follows.

(2) Preparation of TiO _2- based nanocomposites: First, use HNO ₃ (2M) to pretreat anatase nano-TiO ₂ as described in (J.Appl.Polym.Sci., 2015, 132:42047) The paper is hereby incorporated by reference; take an appropriate amount of the partially fluorinated siloxane prepared in step (1) and disperse it in an alcohol solvent (preferably isopropanol) to form a dispersion with a mass fraction of 1% to 5%, Then slowly add an appropriate amount of treated nano-TiO ₂ under magnetic stirring, in which the molar ratio of partially fluorinated siloxane to nano-TiO ₂ is 1:1 to 1:2; the mixture is dispersed ultrasonically, and then magnetically stirred and heated. The TiO _2- based nanocomposite material is obtained by reacting under conditions (40 to 60° C.) (preferably for a time of 6 to 8 hours).

(3) Preparation of weatherproof materials: Weigh 0.05% to 5% of the _TiO2- based nanocomposite material prepared in step (2) and 95% to 99.95% of the solvent according to mass percentage, and stir thoroughly to mix evenly. The sum of the mass percentages of each raw material is 100%; wherein the solvent is an alcohol solvent.

Preparation of multifunctional weatherproof layer: Apply the weatherproof material prepared as above evenly to the surface of masonry cultural relics of various types and materials through spraying or brushing equipment. The concentration of the weatherproof material used is preferably 0.01% to 10%, more preferably 0.05% to 5%, and the percentage is a mass percentage. After the solvent is completely evaporated, a multifunctional weatherproof layer is prepared.

Example 1

Step 1, Preparation of Partially Fluorinated Siloxanes

Measure 0.16ml of 3-aminopropyltrimethoxysilane and 0.26ml of hexafluorocyclopropane trimer respectively; at room temperature and in a nitrogen environment, first add the measured 3-aminopropyltrimethoxysilane to the reaction into the flask; under magnetic stirring, slowly drop the measured hexafluorocyclopropane trimer into the flask; the reaction is carried out at room temperature and in a nitrogen environment for 6 hours to prepare partially fluorinated siloxane.

Step 2, Preparation of _TiO2 -based nanocomposites

First, 2g of anatase nano- _TiO2 (particle size <25nm) was dispersed in nitric acid (2M), and the dispersion was placed in a flask equipped with a reflux condenser and heated (95°C) for 8 hours, and then the mixture was cooled and centrifuged to obtain a solid powder; 1.31g of the partially fluorinated siloxane prepared in step 1 was dispersed in isopropanol to prepare a dispersion with a mass fraction of 1%, and then 0.16g of the treated nano- _TiO2 was slowly added under magnetic stirring; the mixed solution was ultrasonically dispersed for 15 minutes, and then reacted under magnetic stirring and heating (40-60 degrees) conditions for about 6 hours to obtain a _TiO2- based nano-composite material.

Step 3: Prepare weatherproof materials

Measure 0.025g of the product of step 2 and disperse it into 6.3 ml of isopropyl alcohol under magnetic stirring to prepare a weatherproof material with a concentration of 1%. The percentages are mass ratios.

Step 4: Use weatherproof materials to prepare a multifunctional weatherproof layer

The anti-weathering material prepared in step 3 is brushed on the surface of Italian Carrara marble (including quartz calcite marble, porosity <3%) with a surface area of 5×5 square centimeters, and a multifunctional anti-weathering layer is obtained after the solvent is completely evaporated.

The hydrophobicity of the weathering-proof layer was tested, and the results showed that its water contact angle was 157°±3.2°, and the contact angle hysteresis value was 3.5°. The self-cleaning test also showed that the coating had excellent self-cleaning performance (Figure 1). The surface micromorphology of the weathering-proof layer was characterized by scanning electron microscopy, and the weathering-proof layer had a multi-level rough structure at the micro-nano scale (Figure 2). According to EU standards, the capillary hydrophobicity, air permeability and surface color of the weathering-proof layer were tested. The results showed that the weathering-proof layer can effectively reduce the capillary water absorption of porous materials (capillary hydrophobic efficiency is higher than 90% in 4 hours), while maintaining the original air permeability of the substrate (the water vapor diffusion rate loss is only 8%) and surface color (ΔE＜3). The photocatalytic antifouling performance test showed that after 3 hours of UV-A (365nm, 6W) irradiation, the degradation rate of methylene blue attached to the surface of the weathering-proof layer reached 78%, and the color change of the substrate surface was reduced to below the human eye recognition (ΔE＝2.7). Using the OD ₆₀₀ method, the antibacterial properties of the weathering-proof material were tested after 20 minutes of fluorescent light irradiation. The results showed that the material can effectively inhibit the reproduction of Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive). When its concentration was 1.0 g/L, the antibacterial efficiency was 70%, which is about 1.8 times that of the same concentration of rutile nano- _TiO2 .

Example 2

Step 1, preparing partially fluorinated siloxane, the specific material amounts and operation methods are the same as those in Example 1.

Step 2, Preparation of _TiO2 -based nanocomposites

The pretreatment method for nano-TiO ₂ is the same as in Example 1; 1.31g of the partially fluorinated siloxane prepared in step 1 is dispersed in isopropyl alcohol to form a dispersion with a mass fraction of 1%, and then 0.32 g is slowly added under magnetic stirring. g treated nano-TiO ₂ (the molar ratio of partially fluorinated siloxane to nano-TiO ₂ is 1/2); ultrasonically disperse the mixture for 15 minutes, and then react under magnetic stirring and heating (40-60 degrees) The TiO _2- based nanocomposite was prepared in 6.5 hours.

Step 3: Prepare weatherproof materials

Measure 0.025g of the product of step 2 and disperse it into 6.3 ml of isopropyl alcohol under magnetic stirring to prepare a weatherproof material with a concentration of 1%. The percentages are mass ratios.

Step 4: Use weatherproof materials to prepare a multifunctional weatherproof layer.

Brush the weatherproof material prepared in step 3 onto the Italian Carrara marble surface with a surface area of 5 × 5 cm2. After the solvent is completely evaporated, a multifunctional weatherproof layer will be obtained.

The anti-weathering layer has super-hydrophobic and self-cleaning properties, with a water contact angle of 156°±3.8° and a contact angle hysteresis value of 3.0°. The capillary hydrophobicity of the anti-weathering layer and the physical and chemical compatibility with stone were tested according to EU standards. The results showed that the capillary hydrophobicity of the anti-weathering layer was higher than 88% within 4 hours, and the original breathability and surface color of the base material were maintained. The photocatalytic antifouling performance test shows that after 3 hours of UV-A (365nm, 6W) irradiation, the degradation rate of methylene blue attached to the surface of the anti-weathering layer reaches 80% (Figure 3). At the same time, the color change of the surface of the substrate is reduced to the level of human eye recognition. below (ΔE=2.2). The OD ₆₀₀ method antibacterial test shows that the weatherproof material can effectively inhibit the reproduction of Escherichia coli and Staphylococcus aureus. When the current concentration is 0.8g/L, the antibacterial efficiency is 82%, which is about the same concentration of anatase nanoparticles. 1.9 times that of TiO ₂ .

Example 3

In this embodiment, step 1 and step 2 are the same as in embodiment 1.

Step 3: Prepare weatherproof materials

Measure 0.063g of the product of step 2 and disperse it into 7.8 ml of isopropyl alcohol under magnetic stirring to prepare a weatherproof material with a concentration of 1%. The percentages are mass ratios.

Step 4: Use weatherproof materials to prepare a multifunctional weatherproof layer.

The coating material prepared in step 3 is brushed on a sample of Italian Lecce stone (biological calcareous limestone, with a porosity of 35-47%) with a surface area of 5×5 square centimeters, and a multifunctional anti-weathering layer is obtained after the solvent is completely evaporated.

The water contact angle of the obtained anti-weathering layer is 158°±2.8°, and the contact angle hysteresis value is 4.8°, which meets the technical requirements of super-hydrophobic and self-cleaning coatings. The weatherproof performance test shows that the weatherproof layer has high capillary hydrophobicity efficiency (capillary hydrophobicity efficiency is higher than 90% within 24 hours), and the original appearance and physical and chemical properties of the base material are maintained. The photocatalytic antifouling performance test showed that after 3 hours of UV-A (365nm, 6W) irradiation, the degradation rate of methylene blue attached to the surface of the anti-weathering layer reached 73%, and at the same time, the color change on the surface of the substrate was reduced to below the level of human eye recognition (ΔE= 2.4). The OD ₆₀₀ method antibacterial test shows that the weatherproof material can effectively inhibit the reproduction of Escherichia coli and Staphylococcus aureus, and the antibacterial efficiency is significantly higher than that of anatase nano-TiO ₂ at the same concentration.

Example 4

In this example, the preparation method and material dosage of part of the fluorinated siloxane in step 1 are the same as in example 1, but the preparation of TiO2 _- based nanocomposite in step 2 is not carried out. Disperse 0.025g of the product of step 1 in 6.3ml of isopropyl alcohol to prepare a weatherproof material with a concentration of 1%, and then brush the dispersion onto the surface of Italian Carrara marble with a surface area of 5× ^5cm2 until the solvent is completely evaporated. That is, a weatherproof layer is obtained.

The hydrophobicity test shows that the weatherproof layer has superhydrophobic properties, with a water contact angle of 152°±4.5°, but its contact angle hysteresis value is relatively high, at 8.5°. The capillary hydrophobicity test shows that the capillary hydrophobicity efficiency of the weatherproof layer is higher than 85% within 4 hours without changing the breathability and surface color of the base material. However, the photocatalytic antifouling performance test shows that the weatherproof layer does not have antifouling properties, and the methylene blue degradation efficiency on its surface is equivalent to that of the control group without the weatherproof layer, so it does not have photocatalytic antifouling properties. In addition, the OD ₆₀₀ method antibacterial test also shows that the weatherproof material is not antibacterial, and its antibacterial efficiency is lower than that of anatase nano-TiO ₂ at the same concentration. The application effect of this example shows that the addition of nano-TiO ₂ and its covalent interaction with partially fluorinated siloxane (Ti-O-Si) are necessary conditions for the anti-weathering material to have excellent photocatalytic, antifouling and antibacterial properties.

Example 5

In this embodiment, steps 1 and 2 are not performed, and anatase nano-TiO ₂ (particle size <25 nm) is directly used to prepare a weatherproof layer on the surface of the stone substrate. Disperse 0.063g anatase nano- _TiO2 into 6.2ml deionized water to prepare a dispersion with a concentration of 1%, and then brush the dispersion onto the surface of Italian Lecce ^stone with a surface area of 5×5cm2 until the solvent is completely evaporated Then a weatherproof layer is obtained.

The hydrophobic properties show that the weatherproof layer does not have hydrophobic properties, its water contact angle is lower than 60°, and it does not have self-cleaning properties. The surface color was tested using standard methods, and the results showed that the surface color of the base material turned obviously white (ΔE=6.8), which did not meet the requirements for cultural relic protection. The photocatalytic antifouling performance test showed that the degradation rate of methylene blue attached to the surface of the anti-weathering layer was about 40% after 3 hours of UV light irradiation, but the color of the surface of the substrate did not return to below the level of human eye recognition (ΔE = 4.2). The OD ₆₀₀ method antibacterial test also shows that anatase nano-TiO ₂ has a certain antibacterial effect on Escherichia coli, but has poor antibacterial effect on Staphylococcus aureus (Gram-positive). The application effect of this example shows that the introduction of partially fluorinated siloxane is a necessary condition for the weatherproof layer to have superhydrophobic properties. At the same time, the covalent interaction between nanometer TiO ₂ and partially fluorinated siloxane (Ti-O-Si ) is the key reason to improve its photocatalytic antifouling and antibacterial properties.

The above five embodiments do not represent the limited application scope of this patent. For masonry cultural relics of different materials, areas, and degrees of deterioration, the concentration, volume, and dosage of weatherproof materials can be flexibly adjusted to achieve the best superhydrophobic, antifouling, and antibacterial effects.

The present invention has the following beneficial effects:

1. The nanocomposite multifunctional material of the present invention requires few types of raw materials for preparation, has a simple preparation process, and is less time-consuming and energy-consuming. At room temperature, it can be dispersed into a solvent that is harmless to humans and does not pollute the environment by magnetic stirring to prepare an anti-weathering material. The material is applied to the surface of masonry cultural relics by spraying or brushing, and a multifunctional anti-weathering layer with super-hydrophobic, photocatalytic antifouling and antibacterial properties can be obtained after the solvent evaporates quickly. The whole process does not require extreme conditions or special equipment, and has application prospects in daily life and industrial production.

2. The nanocomposite multifunctional material of the present invention forms an anti-weathering layer on the surface of masonry cultural relics, and the water contact angle is 155°~167°, and the hysteresis value of the water droplet contact angle is 3.0°~7.0°. At the same time, the anti-weathering layer also shows stable super anti-wettability to complex water dispersion systems, such as tea, coffee, milk, etc., and shows stable anti-infiltration properties to droplets of different volumes, strictly meeting the technical requirements of super-hydrophobic and self-cleaning coatings.

3. The nanocomposite multifunctional material of the present invention has high performance and can impart superhydrophobicity to masonry cultural relics with a relatively small dosage. For masonry cultural relics with different porosity, the effective dosage of this material is not higher than 25g/m ² .

4. The anti-weathering layer formed by the nanocomposite multifunctional material of the present invention has efficient capillary hydrophobicity. The capillary hydrophobicity of different masonry substrates with porosity of 2% to 45% is higher than 90% after being treated with this material.

5. The anti-weathering layer formed by the nanocomposite multifunctional material of the present invention does not change the original appearance, pattern, color and other characteristics of the masonry cultural relics. The color change of the base surface after weathering treatment is lower than the human eye's visibility (ΔE<3), strictly meeting the requirements for cultural relic protection.

6. The anti-weathering layer formed by the superhydrophobic material of the present invention can effectively protect the breathability of the masonry substrate. After treatment with this material, the water vapor diffusivity loss inside the substrate is less than 10%, which strictly meets the requirements for cultural relic protection.

7. The anti-weathering layer formed by the nano-composite multifunctional material of the present invention has efficient photocatalytic anti-fouling performance. After irradiation with ultraviolet light (UV-A) for 3 hours, it can basically degrade surface organic pollutants and restore the original appearance, pattern, color and other characteristics of the cultural relics (ΔE＜3).

8. The nanocomposite multifunctional material of the present invention has efficient photocatalytic antibacterial performance. When the concentration is 0.5-1.0g/L, it can inhibit Gram-positive/negative bacteria after being irradiated with fluorescent lamps for 20 minutes and cultured for 6 hours. The efficiency reaches more than 80%, and the antibacterial efficiency is about 2 times that of anatase nano _-TiO2 at the same concentration.

9. The anti-weathering layer formed by the nanocomposite multifunctional material of the present invention is resistant to chemical corrosion and shows stable super-wet resistance to solutions with a pH value in the range of 3 to 14; the anti-weathering layer has mechanical wear resistance and is resistant to sandpaper polishing. The super-hydrophobic performance is still maintained after 50 cycles; the anti-weathering layer has environmental weather resistance, and the anti-weathering effect is not significantly weakened after accelerated environmental aging, meeting the requirements for use in open-air environments.

10. The raw materials used in the present invention have moderate cost, are non-toxic to people and the environment, and are green and environmentally friendly.

Claims (6)

1. A surface weatherproof material for open-air masonry cultural relics. The surface weatherproof material includes a uniformly mixed 0.05-5 wt% TiO _2- based nanocomposite and a 95-99.95 wt% solvent, wherein the TiO ₂ The TiO 2 -based nanocomposite is the reaction product of partially fluorinated siloxane and nanometer TiO ₂ , and the solvent is an alcohol solvent. The TiO ₂ -based nanocomposite is formed by dispersing partially fluorinated siloxane in an alcohol solvent. It is prepared by adding nano-TiO ₂ that has been pretreated with nitric acid to a dispersion with a mass fraction of 1% to 5%, and then reacting with stirring and heating at 40-60°C. The molar ratio of partially fluorinated siloxane to nano-TiO ₂ is 1:1 to 1:2, wherein the partially fluorinated siloxane is prepared by reacting an aminoalkyl silane coupling agent with a molar ratio of 1:1 and a hexafluorooxypropane trimer, and the hexafluorinated siloxane contains The structural formula of oxypropane trimer is as follows: . 2. The weatherproofing material for the surface of open-air masonry cultural relics according to claim 1, wherein the aminoalkyl silane coupling agent is one of the following structural formulas or a combination thereof, or/> Wherein R ₁ and R ₂ represent a straight chain or branched chain alkyl group having 1 to 30 carbon atoms. 3. The weatherproofing material for the surface of open-air masonry cultural relics according to claim 2, wherein R ₁ and R ₃ are methyl or ethyl, and R ₂ is propyl or butyl. 4. A method for preparing weather-resistant materials for the surface of open-air masonry cultural relics according to claim 1, comprising the following steps: (1) Preparation of partially fluorinated siloxane: Under inert atmosphere, solvent-free, room temperature conditions, measure the aminoalkyl silane coupling agent and hexafluorooxypropane trimer with a molar ratio of 1:1 respectively, and fully Partially fluorinated siloxane is produced after mixing reaction; (2) Preparation of TiO2 _- based nanocomposites: Disperse partially fluorinated siloxane in an alcohol solvent to form a dispersion with a mass fraction of 1% to 5%, and then slowly add the nanocomposites pretreated with nitric acid under stirring. The TiO _2- based nanocomposite is prepared by the post-reaction of TiO ₂ , in which the molar ratio of partially fluorinated siloxane to nano-TiO ₂ is 1:1 to 1:2; (3) Preparation of weatherproof materials: Weigh 0.05% to 5% of the TiO _2- based nanocomposite material prepared in step (2) and 95% to 99.95% of the solvent according to mass percentage, and stir thoroughly to mix evenly. The solvent is an alcohol solvent. 5. The method according to claim 4, wherein the aminoalkyl silane coupling agent is one of the following structural formulas or a combination thereof: or/> Wherein R ₁ and R ₂ represent a straight chain or branched chain alkyl group having 1 to 30 carbon atoms. 6. The method according to claim 5, wherein R ₁ and R ₃ are methyl or ethyl, and R ₂ is propyl or butyl.