Air-permeable coating material and its application in protection of earthen sites

Abstract

The application belongs to the technical field of coating materials, and particularly relates to a breathable coating material and application of the breathable coating material in protection of earthen sites, and the breathable coating material comprises trifluorochloroethylene water-based fluorine, silico-aluminate, straw, a dispersing agent and water, the mass ratio of the trifluorochloroethylene water-based fluorine, the silico-aluminate, the straw and the water is 5-15:1-5:1-5:75-95, and the volume of the dispersing agent corresponding to 10g of the trifluorochloroethylene water-based fluorine is 1ml-2ml. The breathable coating material has good breathability and does not block air holes, is beneficial to exchange between substances and gases inside and outside the site, and has a good protective effect on the earthen site.

Description

Technical Field

[0001] This invention belongs to the field of coating materials technology, and in particular relates to a breathable coating material and its application in the protection of earthen sites. Background Technology

[0002] The preservation of earthen archaeological sites is a recognized challenge in the field of cultural heritage protection worldwide. Currently, earthen archaeological sites are affected to varying degrees by natural environmental or human-caused damage, with weathering being a leading cause of destruction. In his master's thesis, "Research on Reinforcement Methods and Seismic Stability of Earthen Archaeological Sites," scholar Li Tonglin revealed three methods for protecting earthen archaeological sites from weathering: backfilling, physical reinforcement, and chemical reinforcement. Backfilling is a temporary rescue method used in construction projects, primarily for temporary burial. Physical reinforcement methods, including anchoring and support methods, are applied to severely cracked earthen archaeological sites but are not suitable for most weathering protection. Chemical reinforcement uses chemical materials to improve the surface soil and rock, increasing the cohesion and hardness of the soil, thereby enhancing the site's resistance to weathering. Compared to the other two methods, chemical reinforcement is more effective in adhering to the principle of "restoring the old as it was" while achieving long-term preservation of earthen archaeological sites, offering a more significant advantage in protection.

[0003] Currently, the reinforcement materials used in chemical reinforcement methods can be divided into two main categories: inorganic protective materials and organic protective materials. Inorganic reinforcement materials mainly include lime water, water glass, barium hydroxide, etc. Inorganic materials have good compatibility with inorganic cultural relics, but because their reinforcement mechanism is based on the chemical reaction between the reinforcement material and the site substrate, the reactants can easily block the pores on the surface of the site, thus preventing the reinforcement agent from penetrating. This results in problems such as shallow penetration depth, poor cohesion between the reinforcement material and the site, and weak reinforcement effect. Organic materials include polymers such as acrylates and organic fluorine compounds. Acrylic ester materials have strong adhesion, good permeability, and good film-forming properties, but they exhibit migration in reinforcement materials, resulting in poor aging resistance after reinforcement and a tendency for the surface to yellow, whiten, and discolor. Organic fluorine materials possess good aging resistance, chemical corrosion resistance, oxidation resistance, and excellent mechanical properties, but due to the presence of -CF3 groups, they are highly hydrophobic. Current research has found that hydrophobic polymers can cause interfacial water expansion stress, damaging cultural relics. For example, studies on the hydrophobicity, stability, and permeability of gases such as O2, N2, and CO2 in fluorinated polymers have revealed poor gas permeability and air permeability. When used for site preservation, such materials can easily clog pores, hindering the exchange of substances and gases between the site and its surroundings. Summary of the Invention

[0004] To address the technical problems of existing protective materials having poor permeability, easily clogging pores, and hindering the exchange of substances and gases between the inside and outside of the archaeological site, this invention provides a breathable coating material and its application in the protection of earthen archaeological sites.

[0005] This invention uses trifluorochloroethylene waterborne fluorine, aluminosilicate, straw and dispersant to form a breathable coating material that is waterproof but not water-repellent, has good breathability, does not clog pores, facilitates the exchange of substances and gases between the inside and outside of the site, and has a good protective effect on earthen sites.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A breathable coating material comprises aqueous trifluorochloroethylene fluoride, aluminosilicate, straw, dispersant and water, wherein the mass ratio of aqueous trifluorochloroethylene fluoride, aluminosilicate, straw and water is 5-15:1-5:1-5:75-95, and the volume of dispersant corresponding to each 10g aqueous trifluorochloroethylene fluoride is 1ml-2ml.

[0008] Further specified, the mass ratio of the trifluorochloroethylene aqueous fluoride, aluminosilicate, straw and water is 10:2.5:2.5:85, and the volume of dispersant corresponding to each 10g of trifluorochloroethylene aqueous fluoride is 1.5ml.

[0009] Further specifying, the straw is corn straw, rice straw, or wheat straw; the dispersant is Tween-80, octylphenol polyoxyethylene ether, sodium dodecyl sulfate, or sodium dodecylbenzene sulfonate; and the aluminosilicate is sodium aluminosilicate, potassium aluminosilicate, or calcium aluminosilicate.

[0010] Further specifying, the breathable coating material has an average air permeability coefficient of 0.00586 g / (25cm²). 2 ·h).

[0011] Further specified, the breathable coating material has a water absorption rate of 16.9% and a contact angle of 75.5°.

[0012] A method for preparing the aforementioned breathable coating material includes the following steps:

[0013] S1. Take trifluorochloroethylene aqueous fluoride, aluminosilicate, straw, dispersant and water according to the stated mass proportions;

[0014] S2. The straw is washed, dried, crushed and sieved to obtain straw powder;

[0015] S3. Mix trifluorochloroethylene waterborne fluorine, aluminosilicate, water and straw powder from step S2, then add dispersant and stir evenly to obtain a breathable coating material.

[0016] Further specifying, in step S2, the drying temperature is 75℃~85℃, the drying time is 24h~48h, and the straw powder particle size is 80 mesh~120 mesh.

[0017] Further specifying, in step S3, the stirring conditions are: temperature 30℃~40℃, stirring speed 600r / min~1000r / min, and stirring time 1.5h~2.5h.

[0018] The application of breathable coating materials as described above in the protection of earthen sites.

[0019] Further specifying, the application involves applying a breathable coating material as a paint to the interior walls of the earthen ruins.

[0020] The beneficial effects of this invention are:

[0021] 1. This invention uses trifluorochloroethylene water-based fluorine, aluminosilicate, straw and dispersant to form a breathable coating material. It is waterproof but not water-repellent, has good breathability, does not clog pores, and is conducive to the exchange of materials and gases between the inside and outside of the site, thus playing a good protective role for earthen sites.

[0022] 2. In this invention, straw is used to modify the water-based fluorine of trifluorochloroethylene. On the one hand, straw destroys the original dense structure of the water-based fluorine, making it loose and creating pores, which greatly improves the air permeability of the coating. On the other hand, straw powder itself contains lignin. After high-temperature treatment, the lignin partially decomposes, releasing small molecule gases and leaving pores, which further improves the air permeability of the coating.

[0023] 3. The dispersant added to the coating material of this invention can, on the one hand, play a dispersing role, improve the uniformity, leveling and film-forming properties of the material; on the other hand, it can also play a surface-activating role, reduce the surface tension of the coating material, improve its hydrophilicity, and increase the air permeability and water permeability of cultural relics without affecting the material and energy exchange capacity of the cultural relics themselves.

[0024] 4. This invention selects trifluorochloroethylene waterborne fluorine as the base material and modifies it by adding straw, dispersant and aluminosilicate, etc. While retaining the excellent weather resistance and mechanical properties of trifluorochloroethylene waterborne fluorine, it can slightly reduce the hydrophobicity of the material and increase its water permeability, so that the material has the properties of being waterproof but not water-repellent. In addition, the modified coating material also has good anti-aging properties, achieving the effect of protecting cultural relics from discoloration for a long time and not changing their original historical appearance.

[0025] 5. The raw materials selected in this invention are readily available, the preparation method is simple, and industrial production can be achieved. The resulting coating material has broad application prospects in the protection of earthen sites, especially revolutionary sites. Attached Figure Description

[0026] Figure 1 Photographs of films formed with three different coating materials;

[0027] Figure 2 Infrared spectra of thin films formed with three different coating materials;

[0028] Figure 3 The microstructure of the cross-section of coating film 1 at 50 μm and 25 μm is shown.

[0029] Figure 4 The microstructure of the cross-section of coating 2 film at 50 μm and 25 μm is shown;

[0030] Figure 5 The microstructure of the cross-section of coating film 3 at 50 μm and 25 μm is shown;

[0031] Figure 6 The air permeability of samples treated with three different coatings was tested under the same conditions.

[0032] Figure 7 Contact angle tests were conducted on samples treated with different coatings.

[0033] Figure 8 Dry heat aging tests were conducted on samples treated with three different coatings and an untreated sample.

[0034] Figure 9 Damp heat aging tests were conducted on samples treated with three different coatings and an untreated sample.

[0035] Figure 10 Freeze-thaw aging tests were conducted on samples treated with three different coatings and on untreated samples. Detailed Implementation

[0036] The technical solutions protected by this invention will now be described in detail with reference to the accompanying drawings and embodiments. However, it is obvious that the described embodiments are only some, not all, of the embodiments described herein. All other embodiments obtained by those skilled in the art based on the described embodiments without creative effort are within the scope of protection of this application.

[0037] This invention provides a breathable coating material comprising trifluorochloroethylene aqueous fluorine, aluminosilicate, straw, dispersant and water.

[0038] In this invention, the mass ratio of trifluorochloroethylene aqueous fluoride, aluminosilicate, straw and water is 5-15:1-5:1-5:75-95, and the volume of dispersant corresponding to 10g of trifluorochloroethylene aqueous fluoride is 1ml-2ml.

[0039] In this invention, the mass ratio of trifluorochloroethylene aqueous fluorine, aluminosilicate, straw and water can be 5:1:1:75, 15:5:5:95 (3:1:1:19); 15:1:1:75, 15:1:1:95, 5:1:5:75, 10:1:1:75, 10:5:5:75 (5:1:1:25), 10:1:1:95, 10:2.5:2.5:75 or 10:2.5:2.5:95, or other mass ratios within the defined range.

[0040] In this invention, the volume of the dispersant corresponding to each 10g of trifluorochloroethylene aqueous fluoride is 1ml, 1.2ml, 1.5ml, 1.8ml or 2ml.

[0041] Preferably, the mass ratio of trifluorochloroethylene aqueous fluoride, aluminosilicate, straw and water is 10:2.5:2.5:85, and the volume of dispersant corresponding to 10g of trifluorochloroethylene aqueous fluoride is 1.5ml.

[0042] In this invention, the straw is corn straw, rice straw, or wheat straw, and may also be other crop straw or other plant branches containing lignin.

[0043] In this invention, the aluminosilicate can be sodium aluminosilicate, potassium aluminosilicate, or calcium aluminosilicate.

[0044] In this invention, the dispersant is Tween-80, octylphenol polyoxyethylene ether, sodium dodecyl sulfate, or sodium dodecylbenzene sulfonate.

[0045] The method for preparing the breathable coating material provided by the present invention includes the following steps:

[0046] S1. Take trifluorochloroethylene aqueous fluoride, aluminosilicate, straw, dispersant and water according to the stated mass proportions.

[0047] S2. The straw is washed, dried, crushed and sieved to obtain straw powder.

[0048] In step S2 of this invention, the drying temperature is 75℃~85℃, the drying time is 24h~48h, and the straw powder particle size is 80 mesh~120 mesh.

[0049] In this invention, the drying temperature is 75℃, 80℃, or 85℃, the drying time is 24h, 28h, 30h, 32h, 36h, 40h, 42h, 45h, or 48h, and the straw powder particle size is 80 mesh, 90 mesh, 100 mesh, 110 mesh, or 120 mesh.

[0050] S3. Mix trifluorochloroethylene waterborne fluorine, aluminosilicate, water and straw powder from step S2, then add dispersant and stir evenly to obtain a breathable coating material.

[0051] In this invention, the stirring conditions are: stirring temperature 30℃~40℃, stirring speed 600r / min~1000r / min, and stirring time 1.5h~2.5h.

[0052] In this invention, the stirring temperature is 30℃, 32℃, 35℃, 38℃ or 40℃, the stirring speed is 600r / min, 700r / min, 800r / min, 900r / min or 1000r / min, and the stirring time is 1.5h, 2.0h or 2.5h.

[0053] The breathable coating material obtained by this invention has excellent air permeability, water permeability and anti-aging properties, and can be used as a protective material in the protection of earthen sites.

[0054] The present invention will now be described in detail with reference to specific embodiments.

[0055] It should be noted that, unless otherwise specified, the reagents and medicines used in the following examples and experiments are all conventional commercially available products.

[0056] It should be noted that, unless otherwise specified, the operations used in the following embodiments and experiments are all conventional operations in the art.

[0057] The experimental materials used in the following embodiments are as follows.

[0058] Trichlorofluoroethylene waterborne fluorine, Dalian Zhenbang Fluorine Coatings Co., Ltd.; dispersant is octylphenol polyoxyethylene ether, Tianjin Fuyu Fine Chemical Co., Ltd.; anhydrous sodium sulfate, Tianjin Dingshengxin Chemical Co., Ltd.; sodium aluminosilicate, Anhui Zesheng Technology Co., Ltd.; ultrapure water.

[0059] The experimental instruments used in the following embodiments are shown in Table 1.

[0060] Table 1 Experimental Instruments

[0061] Instrument Name model Manufacturer Colorimeter X-Rite VS-450 X-Rite Instruments, Inc. High-power CNC ultrasonic cleaner KQ-800KDE Kunshan Ultrasonic Instruments Co., Ltd. Electronic balance HX3002T Cixi Tiandong Weighing Instrument Factory Ultrapure water system WP-UP-WF-40 Sichuan Wotel Water Treatment Equipment Co., Ltd. Digital display constant temperature magnetic stirrer 85-2 Hangzhou Instrument & Motor Co., Ltd. Dry heat aging chamber BluepardBHO-401A Shanghai Yiheng Scientific Instruments Co., Ltd. Constant temperature forced air drying oven DHG-9140B(101-2B) Shanghai Langgan Experimental Equipment Co., Ltd. Humid heat aging chamber HCP Memert (Shanghai) Trading Co., Ltd. Freeze-thaw aging chamber PT-2091BI Dongguan Baoda Instrument Company Tungsten filament scanning electron microscope SU3500 Hitachi High Technology Company Ion sputtering instrument BAL-TAC Swiss BAL-TEC company Video optical contact angle tester KRUSS-DSA100 German company KRUSS

[0062] Example 1

[0063] The breathable coating material provided in this embodiment includes the following raw materials in parts by weight: 10 parts of trifluorochloroethylene waterborne fluorine, 2.5 parts of sodium aluminosilicate, 2.5 parts of straw, 1.5 ml of dispersant and 85 parts of water.

[0064] In this embodiment, the straw is corn straw. The dispersant is octylphenol polyoxyethylene ether.

[0065] In this embodiment, the preparation method of the breathable coating material includes the following steps:

[0066] S1. Take trifluorochloroethylene waterborne fluorine, sodium aluminosilicate, straw, dispersant and water according to the stated mass proportions.

[0067] In this embodiment, each portion is weighed in 1g increments, which includes 10g of trifluorochloroethylene waterborne fluorine, 2.5g of sodium aluminosilicate, 2.5g of straw, 1.5ml of dispersant, and 85g of water.

[0068] S2. The straw is washed, dried, crushed and sieved to obtain straw powder;

[0069] In this embodiment, the corn stalks are washed three times, then placed in an 80°C oven for constant temperature drying. After drying, they are crushed and passed through a 120-mesh sieve, and stored at room temperature for later use.

[0070] S3. Mix 10g of trifluorochloroethylene waterborne fluorine, 2.5g of sodium aluminosilicate, 85g of ultrapure water and 2.5g of straw powder, then add 1.5ml of dispersant. Stir at 800r / min for 2 hours at 35℃ until uniform, and obtain a breathable coating material.

[0071] Comparative Example 1

[0072] The coating material provided in this comparative example comprises the following raw materials in parts by weight: 10 parts of waterborne trifluorochloroethylene fluorine and 90 parts of water.

[0073] In this comparative example, the preparation method of the coating material includes the following steps:

[0074] S1. Take the water-based fluorine of trifluorochloroethylene and water according to the stated mass proportions. Weigh each portion as 1g, then take 10g of water-based fluorine of trifluorochloroethylene and 90g of water.

[0075] S2. Mix 10g of trifluorochloroethylene aqueous fluorine and 90g of ultrapure water, and stir at 800r / min for 2 hours at 35℃ until uniform, to obtain the coating material.

[0076] Comparative Example 2

[0077] The coating material provided in this comparative example comprises the following raw materials in parts by weight: 10 parts waterborne trifluorochloroethylene, 2.5 parts sodium aluminosilicate, 2.5 parts straw, and 85 parts water.

[0078] In this comparative example, the straw is corn straw.

[0079] In this comparative example, the preparation method of the coating material includes the following steps:

[0080] S1. Take the following components according to the stated mass: aqueous trifluorochloroethylene fluoride, sodium aluminosilicate, straw, and water. Weigh each component in 1g increments, therefore take 10g of aqueous trifluorochloroethylene fluoride, 2.5g of sodium aluminosilicate, 2.5g of straw, and 85g of water.

[0081] S2. The straw is washed, dried, crushed and sieved to obtain straw powder;

[0082] In this embodiment, the corn stalks are washed three times, then placed in an 80°C oven for constant temperature drying. After drying, they are crushed and passed through a 120-mesh sieve, and stored at room temperature for later use.

[0083] S3. Mix 10g of water-based trifluorochloroethylene, 2.5g of sodium aluminosilicate, 85g of ultrapure water and 2.5g of straw powder, and stir at 800r / min for 2 hours at 35℃ until uniform, to obtain the coating material.

[0084] To verify the performance advantages of the breathable coating material of the present invention, the following tests were conducted using the breathable coating materials provided in the examples and comparative examples.

[0085] Experiment 1: Physical property testing of thin films with different reinforcing coating materials

[0086] Test samples: The coating material of Comparative Example 1, the coating material of Comparative Example 2, and the breathable coating material provided in Example 1 are respectively referred to as coating 1, coating 2, and coating 3.

[0087] The experimental procedure is as follows: 5 ml of each of coating 1, coating 2 and coating 3 are dropped into a 50 mm * 50 mm * 2 mm silicone mold. After standing at a constant temperature of 25 °C for 48 h, the three different reinforced coating films can be obtained by demolding with tweezers.

[0088] (1) Take on-site photos of three different reinforcing coating films, such as Figure 1 As shown, from left to right, they are coating 1, coating 2 and coating 3; and the morphology of the film was observed, the results of which are shown in Table 2.

[0089] (2) Water absorption test: The three different reinforced coating films obtained above were immersed in deionized water for 24 hours. The weight of the films before and after water absorption was measured, and the water absorption rate of the waterborne fluorinated films was calculated. Each group was measured three times, and the average value was taken. The results are shown in Table 2.

[0090] (3) Surface Hardness Test: The hardness of the three different reinforced coating films obtained above was tested according to GB / T 6739-1996 "Determination of Hardness of Paint Film by Pencil Test". Holding a pencil, press down 1 cm at a speed of 1 cm / s and a 45-degree angle for 1 cm, repeating the pressing five times. In the experiment, identify pencils that leave two or more scratches on the film, and record the next digit of the pencil's hardness rating; this is the hardness value of the film. The results are shown in Table 2.

[0091] Table 2 Physical properties of three types of coating films

[0092]

[0093] See Table 2 and Figure 1 A comprehensive comparison of the film performance was conducted from three aspects: water absorption, surface hardness, and morphology. It can be seen that Coating 1 film has uniform film formation and good surface hardness, but suffers from wrinkling and cracking. Coating 2 film exhibits severe peeling and flaking, failing to provide comprehensive protection for earthen archaeological relics from external damage during long-term preservation. Coating 3 film has uniform film formation without bubbles, with a water absorption rate of 16.9%, slightly higher than the other films, indicating reduced surface hydrophobicity and improved water permeability. Furthermore, Coating 3 film has good surface hardness and a certain degree of toughness, making it less prone to peeling and cracking under stress.

[0094] Through comprehensive comparison, the breathable coating material (coating 3) of Example 1 has a good film-forming effect and is most suitable as a weathering-resistant coating for the protection of earthen site cultural relics. It can fully cover the surface of cultural relics and achieve the expected protection effect.

[0095] Experiment 2: Fourier Transform Infrared Analysis of Thin Films with Different Reinforcing Coating Materials

[0096] Test samples: Three different reinforced coating films obtained from coating 1, coating 2 and coating 3 in test 1.

[0097] Experimental methods: Three different reinforced coating films were tested and analyzed using a Fourier transform infrared spectroscopy (FTIR) instrument at a temperature of 4000 nm. -1 ~400cm -1 The results of the infrared spectrum analysis within the range are as follows: Figure 2 As shown.

[0098] See Figure 2 Infrared spectrum, 1727cm -1 The peak at 1074 cm⁻¹ is the C=O absorption peak. -1 and 1220cm -1 The absorption peaks are the stretching vibrations of the COC and CF bonds, respectively, at 935 cm⁻¹. -1 The absorption peak is the -OH bond in carboxylic acid. Comparing the infrared spectra of the three coatings, it was found that the -OH bond absorption peak of coating 3 is sharper. However, the increase in the content of hydroxyl groups helps to improve the hydrophilicity of the coating. Furthermore, improving the hydrophilicity of the coating can enhance the wettability and penetration of the coating on solid cultural relics, thereby achieving a better reinforcement and protection effect. At the same time, for coating 3, it was found that the characteristic groups of trifluorochloroethylene waterborne fluorine are still retained, indicating that coating 3 still has hydrophobicity. It can be seen that the breathable coating material provided by the present invention is waterproof but not water-repellent, meeting the protection requirements of earthen site cultural relics.

[0099] Experiment 3: Microstructure test of films with different reinforcing coating materials. Test samples: films with three different reinforcing coating materials obtained from coating 1, coating 2 and coating 3 in Experiment 1.

[0100] Experimental Method: The coated material film was fixed on the cross-sectional test stage with conductive adhesive. After surface sputtering with gold for 120 seconds, the microstructure of the film was observed under a tungsten filament scanning electron microscope at magnifications of 500x and 1000x. The microstructure of the film cross-section was studied and analyzed. The microstructures of the three different coated material films at 50μm and 25μm under the tungsten filament scanning electron microscope are as follows: Figure 3 , Figure 4 and Figure 5 As shown.

[0101] See Figure 3 , Figure 4 and Figure 5 It is known that the cross-sectional structure of the trichlorofluoroethylene waterborne fluorine film is dense and exhibits delamination. This is because fluorine atoms themselves have extremely low surface energy, and carbon-fluorine chain segments easily migrate to the film surface. As a coating, trichlorofluoroethylene waterborne fluorine can protect cultural relics from external damage to a certain extent, but it also blocks the channels for the exchange of gases and substances between the earthen site relics and the environment. Over time, the relics are prone to peeling due to the inability of salt to precipitate in time, damaging the original historical appearance of the relics. When only straw is added to the modified coating, the cross-section produces pores of varying sizes and even some voids due to the uneven distribution of corn straw. This is consistent with the phenomenon of severe peeling and partial detachment of the film in coating 2. Coating 3 is based on coating 2 with the addition of a dispersant, which evenly disperses the straw powder in the coating, ultimately forming a breathable film with equal and uniformly distributed pore sizes.

[0102] In summary, at the microscopic level, the breathable coating material (coating 3) of Example 1 can improve breathability while ensuring that the structure of the coating itself is not excessively damaged, thereby effectively preventing the reduction of mechanical properties; at the macroscopic level, when applied to the protection of earthen site cultural relics, it can achieve good protective effects without hindering the exchange of substances and gases between the cultural relics and the outside world.

[0103] Test 4, air permeability test

[0104] Test samples: The coating material of Comparative Example 1, the coating material of Comparative Example 2, and the breathable coating material provided in Example 1 are respectively referred to as coating 1, coating 2, and coating 3.

[0105] The experimental procedure is as follows:

[0106] (1) Sample preparation: Sandstone from northern Shaanxi was collected and cut into three 5*5*5cm cubes. After removing the dirt from the sample surface with an ultrasonic cleaner, the samples were dried in an oven at 105℃ for 24 hours to obtain three sandstone samples. Coating 1, coating 2 and coating 3 were evenly applied to the surface of the three sandstone samples with a soft brush. After drying at room temperature for 4 hours, the coating was repeated three times to ensure that the sample surface was completely covered, thus obtaining three simulated samples treated with different coatings.

[0107] (2) Test Analysis: Take a clean 150ml Erlenmeyer flask, fill it with an appropriate amount of deionized water, and place three simulated samples on the flask respectively. Seal the joint with hydrophobic clay to ensure that all water can only escape from the surface of the simulated sample. The initial mass m0 of the whole device is recorded after weighing. The device is placed under constant temperature and humidity conditions (40℃ open oven) for experimental testing. Each cycle is 72h. The mass of the whole device after the test is recorded as m1, that is, the water loss is m = m1 - m0. Calculate the air permeability coefficient. (t is the test time), accumulate 5 test cycles, and calculate the average air permeability coefficient. (n is the test period), the corresponding average air permeability coefficients of different simulated samples are obtained, and the results are as follows: Figure 6 As shown.

[0108] from Figure 6 It can be seen that, under constant temperature and humidity conditions, within the allowable error range, the air permeability of coatings 3 and 2 is far superior to that of coating 1, and the average air permeability coefficient of coating 3 is 0.00586 g / (25cm²). 2 (h) The air permeability of coating 3 is 35.96% higher than that of coating 1. This is because the addition of straw powder disrupts the original dense structure of water-based fluoride, making it loose and porous, thus significantly improving the air permeability of the coating. In addition, straw powder itself contains lignin, a complex aromatic polymer with a three-dimensional network structure. After high-temperature treatment, the lignin partially decomposes, releasing small molecule gases and leaving pores, further improving the air permeability of the coating. Although the air permeability is also improved compared to coating 2, adding only straw powder will result in uneven particle dispersion, affecting the leveling and film-forming properties of the coating, and reducing the adhesion between the coating and the soil artifacts.

[0109] As can be seen, the breathable coating material (coating 3) of Embodiment 1 of the present invention has significantly improved air permeability, and also has good leveling and film-forming properties, thereby improving the adhesion between the coating and the soil artifacts.

[0110] Test 5, Contact Angle Test

[0111] The contact angle reflects the different hydrophilicity and hydrophobicity of materials. A smaller contact angle indicates stronger hydrophilicity, but excessive hydrophilicity can lead to damage to artifacts in humid environments. Conversely, a larger contact angle indicates stronger hydrophobicity, which can prevent external pollutants from affecting artifacts. However, excessive hydrophobicity can significantly reduce the artifact's air and water permeability, affecting its ability to exchange substances with the outside world. Therefore, appropriate hydrophilicity / hydrophobicity is one of the important criteria for selecting coatings suitable for artifact preservation.

[0112] Test samples: The coating material of Comparative Example 1, the coating material of Comparative Example 2, and the breathable coating material provided in Example 1 are respectively referred to as coating 1, coating 2, and coating 3.

[0113] The experimental procedure is as follows: Four sandstone samples of the same size were obtained using the method in Experiment 4; then, paint 1, paint 2 and paint 3 were evenly applied to the surfaces of three of the sandstone samples, and the post-application treatment was the same as in Experiment 4; the remaining sandstone sample was coated with any paint.

[0114] Three simulated samples and an untreated sandstone sample were placed on an optical contact angle testing platform for contact angle testing. Five points were measured for each group of samples, and the median value was used to compare the water affinity of different groups of materials. The results are as follows: Figure 7 As shown, (a) untreated sample, (b) sample treated with paint 1, (c) sample treated with paint 2, and (d) sample treated with paint 3.

[0115] See Figure 7 It can be observed that: the unreinforced sample has a very small contact angle, strong hydrophilicity, and no resistance to external moisture intrusion; the sample treated with coating 1 has an average contact angle of 93.9°, exhibiting obvious hydrophobicity; the samples treated with coating 2 and coating 3 show a slight decrease in contact angle compared to coating 1, because the addition of corn stalk powder and sodium aluminosilicate powder disrupts the compact structure of trifluorochloroethylene waterborne fluorine, increasing its water permeability; in coating 3, octylphenol polyoxyethylene ether acts as a dispersant, while also serving as a surfactant, reducing the surface tension of the film and increasing its hydrophilicity, thus increasing the air permeability and water permeability of the artifact, which is consistent with the above air permeability data.

[0116] Based on the above experiments, it can be seen that the breathable coating material (coating 3) of Example 1 of the present invention can ensure that cultural relics have a certain degree of waterproofness, while not affecting the material and energy exchange capacity of the cultural relics themselves, thus playing a very good protective effect on earthen site cultural relics.

[0117] Experiment 6: Aging Resistance Test

[0118] This experiment tested the aging resistance performance from three aspects: dry heat aging, wet heat aging, and freeze-thaw aging.

[0119] Test samples: The coating material of Comparative Example 1, the coating material of Comparative Example 2, and the breathable coating material provided in Example 1 are respectively referred to as coating 1, coating 2, and coating 3.

[0120] The experimental procedure is as follows: Four sandstone samples of the same size were obtained using the method in Experiment 4; then, coating 1, coating 2 and coating 3 were uniformly applied to the surfaces of three of the sandstone samples, and the post-application treatment was the same as in Experiment 4; the remaining sandstone sample was coated with any coating.

[0121] The test methods and conditions are as follows:

[0122] (1) Dry heat aging: The temperature of the dry heat aging chamber is 105℃±5℃

[0123] (2) Damp heat aging: The temperature of the damp heat aging chamber is 85℃±5℃ and the relative humidity is 65%.

[0124] (3) Freeze-thaw aging: The highest temperature of the high and low temperature cycle aging chamber is 40℃±5℃, the lowest temperature is -30℃±5℃, the humidity is 50%, and one high and low temperature cycle is 8 hours.

[0125] Using 7 days as a cycle, a total of 4 cycles were tested. The color difference between the simulated sample after each aging cycle and the corresponding sample before aging was measured. The color difference changes of the samples treated with three different coatings and the untreated samples after dry heat aging, wet heat aging, and freeze-thaw aging tests are shown below. Figure 8 , Figure 9 and Figure 10 As shown, the aging resistance of different reinforced coating material samples was evaluated according to the color difference evaluation criteria (see Table 3).

[0126] Table 3 Color Difference Evaluation Standards

[0127] Color difference grade Level Requirements ΔE value 0 No color change ≤1.50 1 Very slight discoloration 1.60～3.00 2 Slight discoloration 3.10～6.00 3 Noticeable color change 6.10～9.00 4 Significant discoloration 9.10～12.00 5 Severe discoloration ＞12.00

[0128] See Figure 8 , Figure 9 and Figure 10In the dry heat aging and freeze-thaw aging tests, the unreinforced samples and those treated with coating 2 showed only slight discoloration, while the samples treated with coatings 1 and 3 showed very slight discoloration. This indicates that coating 3 provides better protection than coating 1, as the straw powder contains lignin, which has certain antioxidant properties. Wet heat aging had the greatest impact on the samples; all three coatings treated the simulated samples with slight discoloration. However, the sample treated with coating 3 showed the smallest color difference, due to coating 3's good permeability, allowing for rapid water vapor release. The untreated sandstone sample showed significant discoloration, severely damaging its original appearance. Among the three aging tests, coating 2 had the largest standard deviation because its uneven dispersion affected its leveling properties, preventing it from uniformly protecting the entire sample surface.

[0129] Based on the combined results of the three aging tests, the breathable coating material (coating 3) of Example 1 of this invention has the best anti-aging performance and can achieve the effect of protecting cultural relics from discoloration for a long time without changing their original historical appearance after treatment.

[0130] The performance tests of the coating material described above were conducted using a breathable coating material formed from 10 parts of trifluorochloroethylene waterborne fluorine, 2.5 parts of sodium aluminosilicate, 2.5 parts of straw, 1.5 ml of dispersant (octylphenol polyoxyethylene ether), and 85 parts of water. When other types of dispersants were selected or the mass ratio of the raw materials was changed, the resulting breathable coating material also exhibited similar effects to the coating material in Example 1. That is, the coating material is waterproof but not water-repellent. While having good weather resistance and mechanical properties, it slightly reduces the hydrophobicity of the material and significantly improves the breathability of the reinforced coating. It does not clog the pores, so as to facilitate the exchange of substances and gases inside and outside the site, and plays a very good protective role for the earthen site.

[0131] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A breathable coating material, characterized in that, The raw materials include: aqueous trifluorochloroethylene fluoride, aluminosilicate, straw, dispersant and water, wherein the mass ratio of aqueous trifluorochloroethylene fluoride, aluminosilicate, straw and water is 5~15:1~5:1~5:75~95; The method for preparing the breathable coating material includes the following steps: S1. Take trifluorochloroethylene aqueous fluoride, aluminosilicate, straw, dispersant and water according to the stated mass proportions; S2. Straw is washed, dried, pulverized and sieved to obtain straw powder; the drying temperature is 75℃~85℃, the drying time is 24h~48h, and the straw powder particle size is 80 mesh~120 mesh. S3. Mix trifluorochloroethylene waterborne fluorine, aluminosilicate, water and straw powder from step S2, then add dispersant and stir evenly to obtain a breathable coating material.

2. The breathable coating material according to claim 1, characterized in that, The mass ratio of the trifluorochloroethylene aqueous fluorine, aluminosilicate, straw, and water is 10:2.5:2.5:

85.

3. The breathable coating material according to claim 1, characterized in that, The straw is corn straw, rice straw, or wheat straw; the dispersant is Tween-80, octylphenol polyoxyethylene ether, sodium dodecyl sulfate, or sodium dodecylbenzene sulfonate; the aluminosilicate is sodium aluminosilicate, potassium aluminosilicate, or calcium aluminosilicate.

4. The breathable coating material according to claim 2, characterized in that, The breathable coating material has an average air permeability coefficient of 0.00586 g / (25cm²). 2 ·h).

5. The breathable coating material according to claim 2, characterized in that, The breathable coating material has a water absorption rate of 16.9% and a contact angle of 75.5°.

6. A method for preparing the breathable coating material as described in claim 1, characterized in that, The preparation method includes the following steps: S1. Take trifluorochloroethylene aqueous fluoride, aluminosilicate, straw, dispersant and water according to the stated mass proportions; S2. Straw is washed, dried, pulverized and sieved to obtain straw powder; the drying temperature is 75℃~85℃, the drying time is 24h~48h, and the straw powder particle size is 80 mesh~120 mesh. S3. Mix trifluorochloroethylene waterborne fluorine, aluminosilicate, water and straw powder from step S2, then add dispersant and stir evenly to obtain a breathable coating material.

7. The preparation method according to claim 6, characterized in that, In step S3, the stirring conditions are: temperature 30℃~40℃, stirring speed 600r / min~1000r / min, and stirring time 1.5h~2.5h.

8. The application of the breathable coating material as described in claim 1 in the protection of earthen sites.

9. The application according to claim 8, characterized in that, The application involves using a breathable coating material as a paint to coat the interior walls of the earthen ruins.

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