Long-acting active self-cleaning car tarpaulin material and preparation method thereof

Abstract

The application discloses a long-acting active self-cleaning automobile tarpaulin material and a preparation method thereof. The long-acting active self-cleaning automobile tarpaulin material is prepared by the following steps: hydrophilic activation and loading of hydrophilic surfactant on amorphous calcium carbonate microparticles, in-situ growth of silicon dioxide nanoparticles on the surface of the amorphous calcium carbonate microparticles to form super-hydrophilic microcapsules, uniform dispersion of the super-hydrophilic microcapsules in PVC paste resin, addition of a plasticizer and a stabilizer, coating on the surface of a polyester base cloth through a knife coating process, and curing at room temperature. The long-acting active self-cleaning automobile tarpaulin material is obtained. In the application, the amorphous calcium carbonate microparticles with high specific surface area are used to load the hydrophilic surfactant, so that the coating is super-hydrophilic, and the silicon dioxide nanoparticles are used for encapsulation, so that the loss of the surfactant is significantly delayed, and the long-acting active self-cleaning performance is realized. Meanwhile, the addition of the calcium carbonate particles can significantly strengthen the mechanical properties of the automobile tarpaulin material and prolong the service life of the automobile tarpaulin material.

Description

Technical Field

[0001] This invention relates to the field of functional materials preparation technology, and in particular to a long-lasting, active self-cleaning automotive tarpaulin material and its preparation method. Background Technology

[0002] As a barrier protecting transported goods, truck tarpaulins inevitably suffer from environmental contaminants such as dust, bird droppings, salt, and cargo-borne pollutants (e.g., raw food scraps, grease, engine oil) during long-term outdoor use, severely reducing their cleanliness and hygiene, leading to health risks and economic losses. While frequent manual cleaning can alleviate this problem, it is time-consuming, labor-intensive, and resource-intensive, and stubborn stains are difficult to completely remove. Regularly replacing truck tarpaulins as consumables not only increases costs but also contradicts national sustainable development policies.

[0003] If automotive tarpaulin materials were endowed with active self-cleaning capabilities—meaning they could clean themselves during service without human intervention—the aforementioned problems could be effectively solved. In recent years, with the rise of biomimetic technology, hydrophilic / superhydrophilic materials have achieved self-cleaning functions and have seen some applications. For example, the self-cleaning technology in air conditioning heat exchangers uses a hydrophilic coating, where water droplets on its surface can quickly spread into a water film, effectively isolating contaminants and causing them to slide off rapidly. However, due to insufficient hydrophilicity (i.e., a water contact angle > 10°, failing to achieve superhydrophilicity), these coatings can only achieve self-cleaning of dust, not stubborn stains like oil. Adding hydrophilic substances like surfactants to the material can effectively improve hydrophilicity, but surfactants are easily lost, especially in harsh outdoor environments, accelerating their loss and resulting in a short lifespan for hydrophilic / superhydrophilic materials. Therefore, developing an automotive tarpaulin material that combines excellent active self-cleaning capabilities with long-lasting performance remains a significant challenge. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a long-lasting, active self-cleaning automotive tarpaulin material and its preparation method. The material utilizes amorphous calcium carbonate micron particles with high specific surface area loaded with hydrophilic surfactants to impart superhydrophilicity to the coating. Furthermore, encapsulation with silica nanoparticles significantly delays surfactant loss, thereby achieving long-lasting active self-cleaning performance. Simultaneously, the addition of calcium carbonate particles can significantly enhance the mechanical properties of the automotive tarpaulin material and extend its service life.

[0005] The objective of this invention is achieved as follows: a method for preparing a long-lasting, active self-cleaning automotive tarpaulin material, comprising the following steps:

[0006] Step 1) Add 0.3-0.5 parts by weight of dopamine hydrochloride to 30-50 parts by weight of deionized water, and mechanically stir for 5-10 min to completely dissolve the dopamine hydrochloride. Then add 1-3 parts by weight of amorphous calcium carbonate micron particles to the solution and keep stirring for 1-2 h to disperse the particles evenly and obtain a calcium carbonate micron particle suspension.

[0007] Step 2) The calcium carbonate micron particle suspension from Step 1) is dried in a low-temperature hollow environment at -30°C and 10 Pa for 24-36 h using freeze-drying technology to obtain hydrophilic activated calcium carbonate micron particles.

[0008] Step 3) Redisperse 1-3 parts by weight of the hydrophilic activated calcium carbonate microparticles from Step 2) in 30-50 parts by weight of deionized water, add 0.5-1 parts by weight of hydrophilic surfactant during mechanical stirring, and continue stirring for 0.5-1 h to obtain a calcium carbonate microparticle suspension loaded with hydrophilic surfactant.

[0009] Step 4) The calcium carbonate micron particle suspension loaded with hydrophilic surfactant from step 3) is freeze-dried again according to the method in step 2) to obtain calcium carbonate micron particles loaded with hydrophilic surfactant.

[0010] Step 5) Disperse 1-3 parts by mass of calcium carbonate microparticles loaded with hydrophilic surfactant from step 4) into 80-100 parts by mass of deionized water, and mechanically stir until uniformly dispersed. Then, add 0.2-0.5 parts by mass of sodium hydroxide and 0.6-1.5 parts by mass of silica precursor in sequence, and stir and react at 50°C for 16-24 h to grow silica nanoparticles in situ on the surface of calcium carbonate microparticles loaded with hydrophilic surfactant, thereby obtaining a superhydrophilic microcapsule suspension.

[0011] Step 6) Place the superhydrophilic microcapsule suspension from Step 5) in a 100 °C forced-air drying oven and heat and dry for 6-8 hours to obtain superhydrophilic microcapsule powder;

[0012] Step 7) Add 1-3 parts by weight of the superhydrophilic microcapsule powder from Step 6) to 20-30 parts by weight of volatile organic solvent, then add 3-8 parts by weight of PVC paste resin, 0.1-0.5 parts by weight of plasticizer and 0.1-0.5 parts by weight of stabilizer in sequence. Stir mechanically for 1-2 hours to disperse and dissolve the components evenly. Finally, coat the polyester base fabric with a knife coating process and dry and cure at room temperature for 8-12 hours to obtain a long-lasting active self-cleaning automotive tarpaulin material.

[0013] Furthermore, the amorphous calcium carbonate micron particles mentioned in step 1) are spherical particle aggregates with a particle size of 5-30 μm and a rough surface structure.

[0014] Furthermore, the hydrophilic surfactant mentioned in step 3) is at least one of Chemours FS-31, FS-35 and FS-3100.

[0015] Furthermore, the silica precursor mentioned in step 5) is at least one of tetraethyl orthosilicate, methyltrimethoxysilane, and methyltriethoxysilane.

[0016] Furthermore, the volatile organic solvent mentioned in step 7) is at least one of acetone, ethanol and ethyl acetate, the plasticizer is at least one of trioctyl trimellitate, dibutyl phthalate and citrate, and the stabilizer is at least one of modified polyether, phosphite and calcium-zinc composite stabilizer.

[0017] Another aspect of the objective of this invention is achieved as follows: a long-lasting, actively self-cleaning automotive tarpaulin material, prepared using the above-described method, comprising: 1-3 parts by weight of amorphous calcium carbonate micron particles, 0.3-0.5 parts by weight of dopamine hydrochloride, 0.5-1 parts by weight of a hydrophilic surfactant, 0.6-1.5 parts by weight of silica nanoparticles, 3-8 parts by weight of PVC paste resin, 0.1-0.5 parts by weight of a plasticizer, and 0.1-0.5 parts by weight of a stabilizer.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) By using amorphous calcium carbonate microparticles with high specific surface area to load hydrophilic surfactants, the loading capacity can be effectively increased, giving the car tarpaulin excellent superhydrophilicity and active self-cleaning function. (2) By hydrophilically activating the calcium carbonate microparticles with dopamine hydrochloride, the adsorption of hydrophilic surfactants can be strengthened, playing an anchoring role, thereby preventing the surfactants from excessively migrating into the interior of the car tarpaulin, reducing mechanical properties, and slowing down the loss of surfactants during service. (3) By encapsulating the calcium carbonate microparticles with in-situ grown silica nanoparticles, the loss of surfactants is prevented, significantly extending the service life of the car tarpaulin. (4) The long-lasting active self-cleaning car tarpaulin material can use rainwater, frost, dew and snow in the natural environment to achieve self-cleaning during service, without human intervention, and can remove pollutants such as dust, bird droppings and oil stains, solving the problems of time-consuming, labor-intensive, resource-intensive and stubborn stains that are difficult to remove in traditional solutions. (5) The doping of hard calcium carbonate particles can significantly enhance the mechanical properties of the car tarpaulin material and extend its service life. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0020] Figure 1 The images show the appearance and superhydrophilicity of the long-lasting active self-cleaning automotive tarpaulin material in Example 1, where a is a macroscopic photograph and b is a water contact angle diagram.

[0021] Figure 2 This is a diagram illustrating the active self-cleaning of dust in the long-lasting active self-cleaning automotive tarpaulin material of Example 2.

[0022] Figure 3 The diagram shows the active self-cleaning properties of oil stains on different automotive tarpaulin materials, where a is the long-lasting active self-cleaning automotive tarpaulin material in Example 3, and b is the commercially available hydrophilic automotive tarpaulin material in Comparative Example 1.

[0023] Figure 4 The diagram shows the distribution of hydrophilic surfactants in different automotive tarpaulin materials, where a is the superhydrophilic automotive tarpaulin material in Comparative Example 2, and b is the long-lasting active self-cleaning automotive tarpaulin material in Example 3.

[0024] Figure 5 The image shows the self-cleaning effect of bird droppings after 180 days of outdoor placement of long-lasting self-cleaning car tarpaulin materials prepared with different amounts of dopamine hydrochloride in Example 4. In the image, a represents the self-cleaning effect before self-cleaning, b represents the self-cleaning effect during self-cleaning, and c represents the self-cleaning effect after self-cleaning.

[0025] Figure 6 The image shows the active self-cleaning of oil stains on long-lasting, actively self-cleaning automotive tarpaulin materials prepared with different amounts of hydrophilic surfactants in Example 5. In the image, a represents the active self-cleaning process, b represents the active self-cleaning process, and c represents the active self-cleaning process.

[0026] Figure 7 The rate of loss of hydrophilic surfactant in long-lasting, active self-cleaning automotive tarpaulin materials prepared with different amounts of silica precursor in Example 6 was measured.

[0027] Figure 8 The mechanical properties and abrasion resistance of long-lasting active self-cleaning automotive tarpaulin materials prepared with different amounts of hydrophilic microcapsules in Example 7 are shown in the figure. In the figure, a represents hardness and elastic modulus, and b represents the surface micromorphology of different long-lasting active self-cleaning automotive tarpaulin materials after abrasion. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] A method for preparing a long-lasting, active self-cleaning automotive tarpaulin material includes the following steps:

[0030] Step 1) Add 0.3-0.5 parts by weight of dopamine hydrochloride to 30-50 parts by weight of deionized water, and mechanically stir for 5-10 min to completely dissolve the dopamine hydrochloride. Then add 1-3 parts by weight of amorphous calcium carbonate micron particles to the solution and keep stirring for 1-2 h to disperse the particles evenly, thereby obtaining a calcium carbonate micron particle suspension. The amorphous calcium carbonate micron particles are spherical aggregates with a particle size of 5-30 μm and a rough surface structure.

[0031] Step 2) The calcium carbonate micron particle suspension from Step 1) is dried in a low-temperature hollow environment at -30°C and 10 Pa for 24-36 h using freeze-drying technology to obtain hydrophilic activated calcium carbonate micron particles.

[0032] Step 3) Redisperse 1-3 parts by weight of the hydrophilically activated calcium carbonate microparticles from Step 2) in 30-50 parts by weight of deionized water, add 0.5-1 parts by weight of a hydrophilic surfactant during mechanical stirring, and continue stirring for 0.5-1 h to obtain a calcium carbonate microparticle suspension loaded with a hydrophilic surfactant; the hydrophilic surfactant is at least one of Chemours FS-31, FS-35 and FS-3100.

[0033] Step 4) The calcium carbonate micron particle suspension loaded with hydrophilic surfactant from step 3) is freeze-dried again according to the method in step 2) to obtain calcium carbonate micron particles loaded with hydrophilic surfactant.

[0034] Step 5) Disperse 1-3 parts by mass of the calcium carbonate microparticles loaded with hydrophilic surfactant from step 4) into 80-100 parts by mass of deionized water, and mechanically stir until uniformly dispersed. Then, add 0.2-0.5 parts by mass of sodium hydroxide and 0.6-1.5 parts by mass of silica precursor in sequence, and stir at 50°C for 16-24 h to grow silica nanoparticles in situ on the surface of the calcium carbonate microparticles loaded with hydrophilic surfactant, thereby obtaining a superhydrophilic microcapsule suspension. The silica precursor is at least one of tetraethyl orthosilicate, methyltrimethoxysilane and methyltriethoxysilane.

[0035] Step 6) Place the superhydrophilic microcapsule suspension from Step 5) in a 100 °C forced-air drying oven and heat and dry for 6-8 hours to obtain superhydrophilic microcapsule powder;

[0036] Step 7) Add 1-3 parts by weight of the superhydrophilic microcapsule powder from Step 6) to 20-30 parts by weight of volatile organic solvent, then add 3-8 parts by weight of PVC paste resin, 0.1-0.5 parts by weight of plasticizer and 0.1-0.5 parts by weight of stabilizer in sequence. Stir mechanically for 1-2 hours to disperse and dissolve the components evenly. Finally, coat the polyester base fabric with a knife coating process and dry and cure at room temperature for 8-12 hours to obtain a long-lasting active self-cleaning automotive tarpaulin material. The volatile organic solvent is at least one of acetone, ethanol and ethyl acetate, the plasticizer is at least one of trioctyl trimellitate, dibutyl phthalate and citrate, and the stabilizer is at least one of modified polyether, phosphite and calcium-zinc composite stabilizer.

[0037] A long-lasting, active self-cleaning automotive tarpaulin material is prepared using the above-mentioned method. The long-lasting, active self-cleaning automotive tarpaulin material comprises: 1-3 parts by weight of amorphous calcium carbonate micron particles, 0.3-0.5 parts by weight of dopamine hydrochloride, 0.5-1 parts by weight of a hydrophilic surfactant, 0.6-1.5 parts by weight of silica nanoparticles, 3-8 parts by weight of PVC paste resin, 0.1-0.5 parts by weight of plasticizer, and 0.1-0.5 parts by weight of stabilizer.

[0038] Example 1:

[0039] A method for preparing a long-lasting, active self-cleaning automotive tarpaulin material is disclosed. In this embodiment, the amorphous calcium carbonate micron particles are spherical aggregates with a particle size of 5 μm and a rough surface structure. The hydrophilic surfactant is Chemours FS-31, the silica precursor is tetraethyl orthosilicate, the volatile organic solvent is acetone, the plasticizer is trioctyl trimellitate, and the stabilizer is modified polyether. The preparation steps are as follows:

[0040] Step 1) Add 0.3 parts by mass of dopamine hydrochloride to 30 parts by mass of deionized water and stir mechanically for 5 min to completely dissolve the dopamine hydrochloride. Then add 1 part by mass of amorphous calcium carbonate micron particles to the solution and keep stirring for 1 h to disperse the particles evenly and obtain a calcium carbonate micron particle suspension.

[0041] Step 2) The calcium carbonate micron particle suspension from Step 1) is dried for 24 hours at -30°C and 10 Pa in a low-temperature hollow environment using freeze-drying technology to obtain hydrophilic activated calcium carbonate micron particles.

[0042] Step 3) The hydrophilically activated calcium carbonate microparticles (1 part by mass) from Step 2) are redispersed in 30 parts by mass of deionized water. During mechanical stirring, 0.5 parts by mass of Chemours FS-31 are added and stirring is continued for 0.5 h to obtain a calcium carbonate microparticle suspension loaded with Chemours FS-31.

[0043] Step 4) The calcium carbonate microparticle suspension loaded with Chemours FS-31 from Step 3) is freeze-dried again according to the method in Step 2) to obtain calcium carbonate microparticles loaded with Chemours FS-31.

[0044] Step 5) Disperse the calcium carbonate microparticles (1 part by mass) loaded with Chemours FS-31 in Step 4) into 80 parts by mass of deionized water and mechanically stir until uniformly dispersed. Then add 0.2 parts by mass of sodium hydroxide and 0.6 parts by mass of tetraethyl orthosilicate in sequence, and stir at 50 °C for 16 h to grow silica nanoparticles in situ on the surface of the calcium carbonate microparticles loaded with Chemours FS-31, thereby obtaining a superhydrophilic microcapsule suspension.

[0045] Step 6) Place the superhydrophilic microcapsule suspension from Step 5) in a 100 °C forced-air drying oven and heat and dry for 6 hours to obtain superhydrophilic microcapsule powder;

[0046] Step 7) Add 1 part by weight of the superhydrophilic microcapsule powder from Step 6) to 20 parts by weight of acetone, then add 3 parts by weight of PVC paste resin, 0.1 parts by weight of trioctyl trimellitate and 0.1 parts by weight of modified polyether in sequence. Stir mechanically for 1 h to disperse and dissolve the components evenly. Finally, coat the polyester base fabric with a knife coating process and dry and cure at room temperature for 8 h to obtain a long-lasting active self-cleaning automotive tarpaulin material.

[0047] like Figure 1 As shown in image a, this is a macroscopic photograph of the long-lasting, self-cleaning automotive tarpaulin material. It is intact, dense, and uniform, with no defects such as cracks or holes observed. Furthermore, it can be seen that water droplets (dyed blue) placed on the surface quickly spread into an extremely thin, circular film. This is further supported by magnified optical micrographs. Figure 1 (b) It can be seen that the water contact angle of the long-lasting active self-cleaning automotive tarpaulin material surface is only ~3°, which is far below the critical contact angle of 10°, demonstrating excellent superhydrophilicity.

[0048] Example 2:

[0049] A method for preparing a long-lasting, active self-cleaning automotive tarpaulin material. In this embodiment, the amorphous calcium carbonate micron particles are spherical aggregates with a particle size of 30 μm and a rough surface structure. The hydrophilic surfactant is Chemours FS-35, the silica precursor is methyltrimethoxysilane, the volatile organic solvent is ethanol, the plasticizer is dibutyl phthalate, and the stabilizer is phosphite. The preparation steps are as follows:

[0050] Step 1) Add 0.5 parts by mass of dopamine hydrochloride to 50 parts by mass of deionized water and stir mechanically for 10 min to completely dissolve the dopamine hydrochloride. Then add 3 parts by mass of amorphous calcium carbonate micron particles to the solution and keep stirring for 2 h to disperse the particles evenly and obtain a calcium carbonate micron particle suspension.

[0051] Step 2) The calcium carbonate micron particle suspension from Step 1) was dried for 36 h in a low-temperature hollow environment at -30°C and 10 Pa using freeze-drying technology to obtain hydrophilic activated calcium carbonate micron particles.

[0052] Step 3) The hydrophilically activated calcium carbonate microparticles (3 parts by mass) from Step 2) are redispersed in 50 parts by mass of deionized water. During mechanical stirring, 1 part by mass of Chemours FS-35 is added and stirring is continued for 1 h to obtain a calcium carbonate microparticle suspension loaded with Chemours FS-35.

[0053] Step 4) The calcium carbonate micron particle suspension loaded with Chemours FS-35 from Step 3) is freeze-dried again according to the method in Step 2) to obtain calcium carbonate micron particles loaded with Chemours FS-35.

[0054] Step 5) Disperse the calcium carbonate microparticles (3 parts by mass) loaded with Chemours FS-35 in Step 4) into 100 parts by mass of deionized water and mechanically stir until uniformly dispersed. Then add 0.5 parts by mass of sodium hydroxide and 1.5 parts by mass of methyltrimethoxysilane in sequence, and stir at 50 °C for 24 h to grow silica nanoparticles in situ on the surface of the calcium carbonate microparticles loaded with Chemours FS-35, thereby obtaining a superhydrophilic microcapsule suspension.

[0055] Step 6) Place the superhydrophilic microcapsule suspension from Step 5) in a 100 °C forced-air drying oven and heat and dry for 8 hours to obtain superhydrophilic microcapsule powder;

[0056] Step 7) Add the superhydrophilic microcapsule powder (3 parts by weight) from Step 6) to 30 parts by weight of ethanol, then add 8 parts by weight of PVC paste resin, 0.5 parts by weight of dibutyl phthalate and 0.5 parts by weight of phosphite in sequence. Stir mechanically for 2 hours to disperse and dissolve the components evenly. Finally, coat the polyester base fabric with a knife coating process and dry and cure at room temperature for 12 hours to obtain a long-lasting active self-cleaning automotive tarpaulin material.

[0057] Figure 2 This diagram illustrates the self-cleaning properties of long-lasting, active self-cleaning automotive tarpaulin materials. It shows that the tarpaulin surface initially accumulates a large amount of dust (turned yellow). When water droplets are then added to the surface, they quickly spread to form a water film, lifting and carrying the dust away from the tarpaulin surface, thus achieving complete self-cleaning. This is something traditional automotive tarpaulin materials cannot achieve; when water droplets are applied to traditional tarpaulin surfaces, they adhere along with the dust, making them even more difficult to remove.

[0058] Example 3:

[0059] A method for preparing a long-lasting, active self-cleaning automotive tarpaulin material. In this embodiment, the amorphous calcium carbonate micron particles are spherical aggregates with a particle size of 20 μm and a rough surface structure. The hydrophilic surfactant is Chemours FS-3100, the silica precursor is methyltriethoxysilane, the volatile organic solvent is ethyl acetate, the plasticizer is citrate ester, and the stabilizer is a calcium-zinc composite stabilizer. The preparation steps are as follows:

[0060] Step 1) Add 0.4 parts by mass of dopamine hydrochloride to 40 parts by mass of deionized water and stir mechanically for 8 min to completely dissolve the dopamine hydrochloride. Then add 2 parts by mass of amorphous calcium carbonate micron particles to the solution and keep stirring for 1.5 h to disperse the particles evenly and obtain a calcium carbonate micron particle suspension.

[0061] Step 2) The calcium carbonate micron particle suspension from Step 1) is dried in a low-temperature hollow environment at -30 °C and 10 Pa for 30 h using freeze-drying technology to obtain hydrophilic activated calcium carbonate micron particles.

[0062] Step 3) The hydrophilically activated calcium carbonate microparticles (2 parts by mass) from Step 2) are redispersed in 40 parts by mass of deionized water. During mechanical stirring, 0.7 parts by mass of Chemours FS-3100 are added and stirring is continued for 0.8 h to obtain a calcium carbonate microparticle suspension loaded with Chemours FS-3100.

[0063] Step 4) The calcium carbonate micron particle suspension loaded with Chemours FS-3100 from Step 3) is freeze-dried again according to the method in Step 2) to obtain calcium carbonate micron particles loaded with Chemours FS-3100.

[0064] Step 5) Disperse the calcium carbonate microparticles (2 parts by mass) loaded with Chemours FS-3100 in Step 4) into 90 parts by mass of deionized water and mechanically stir until uniformly dispersed. Then add 0.3 parts by mass of sodium hydroxide and 1 part by mass of methyltriethoxysilane in sequence, and stir at 50 °C for 20 h to grow silica nanoparticles in situ on the surface of the calcium carbonate microparticles loaded with Chemours FS-3100, and obtain a superhydrophilic microcapsule suspension.

[0065] Step 6) Place the superhydrophilic microcapsule suspension from Step 5) in a 100 °C forced-air drying oven and heat and dry for 7 hours to obtain superhydrophilic microcapsule powder;

[0066] Step 7) Add the superhydrophilic microcapsule powder (2 parts by mass) from Step 6) to 25 parts by mass of ethyl acetate, then add 5 parts by mass of PVC paste resin, 0.3 parts by mass of citrate ester and 0.3 parts by mass of calcium-zinc composite stabilizer in sequence. Stir mechanically for 1.5 h to disperse and dissolve the components evenly. Finally, coat the polyester base fabric with a knife coating process and dry and cure at room temperature for 10 h to obtain a long-lasting active self-cleaning automotive tarpaulin material.

[0067] Comparative Example 1:

[0068] In this embodiment, a commercially available hydrophilic coating (hydrophilic acrylic resin) was used. Following the product instructions, it was coated onto the surface of a polyester base fabric using a knife-coating process. After the coating dried and cured, a commercially available hydrophilic automotive tarpaulin material was obtained. This material was used to compare and illustrate the performance differences between the commercial product and the long-lasting active self-cleaning automotive tarpaulin materials prepared in Examples 1-3.

[0069] Comparative Example 2:

[0070] In this embodiment, referencing the preparation method of commercially available superhydrophilic self-cleaning coatings for photovoltaic glass, hydrophilic surfactants are directly added to the coating instead of using amorphous calcium carbonate microparticles for loading. This is used to compare and illustrate the effect of loading hydrophilic surfactants onto amorphous calcium carbonate microparticles and enhancing mechanical properties. The preparation steps are as follows:

[0071] Step 1) Add 0.7 parts by weight of Chemours FS-3100, 5 parts by weight of PVC paste resin, 0.3 parts by weight of citrate and 0.3 parts by weight of calcium-zinc composite stabilizer to 25 parts by weight of ethyl acetate in sequence. Stir mechanically for 1.5 h to disperse and dissolve the components evenly. Finally, coat the polyester base fabric with a knife coating process and dry and cure at room temperature for 10 h to obtain the superhydrophilic automotive tarpaulin material.

[0072] Comparative Example 3:

[0073] In this embodiment, the preparation method is referenced from reported literature. Only porous particles are loaded with hydrophilic surfactants, but the porous particles are not hydrophilically activated or encapsulated with nanoparticles. This is used to compare and illustrate the effects of hydrophilically activated anchoring of surfactants and nanoparticle encapsulation in slowing surfactant loss. The preparation steps are as follows:

[0074] Step 1) Disperse 2 parts by mass of amorphous calcium carbonate micron particles in 40 parts by mass of deionized water, add 0.7 parts by mass of Chemours FS-3100 during mechanical stirring, and continue stirring for 0.8 h to obtain a calcium carbonate micron particle suspension loaded with Chemours FS-3100.

[0075] Step 2) The calcium carbonate micron particle suspension loaded with Chemours FS-3100 from Step 1) was dried for 30 h in a low temperature hollow environment at -30 °C and 10 Pa using freeze-drying technology to obtain calcium carbonate micron particles loaded with Chemours FS-3100.

[0076] Step 3) Add 2 parts by mass of calcium carbonate micronized particles loaded with Chemours FS-3100 from Step 2) to 25 parts by mass of ethyl acetate, then add 5 parts by mass of PVC paste resin, 0.3 parts by mass of citrate ester and 0.3 parts by mass of calcium-zinc composite stabilizer in sequence. Stir mechanically for 1.5 h to disperse and dissolve the components evenly. Finally, coat the polyester base fabric with a knife coating process and dry and cure at room temperature for 10 h to obtain an active self-cleaning automotive tarpaulin material.

[0077] Table 1. Comparison of the technical effects of the above embodiments and comparative examples

[0078]

[0079] As shown in Table 1, Examples 1 to 3 produced a long-lasting, self-cleaning automotive tarpaulin material by hydrophilically activating amorphous calcium carbonate microparticles and loading them with hydrophilic surfactants, in-situ growing silica nanoparticles, encapsulating them to form superhydrophilic microcapsules, doping the superhydrophilic microcapsules with reinforced PVC paste resin, and then applying a knife coating. This material not only possesses excellent superhydrophilicity (water contact angle: 2.7-3.2°), active self-cleaning properties for dust (self-cleaning rate: 100%), active self-cleaning properties for oil stains (self-cleaning rate: 100%), and active self-cleaning properties for bird droppings (self-cleaning rate: 100%), but also excellent mechanical properties (hardness: 0.5-0.54 GPa, elastic modulus: 39.2-40.3 GPa), abrasion resistance (friction resistance cycles: 320-350), and outdoor service life (480-520 days), breaking through the bottleneck of superhydrophilic materials having both excellent functionality and durability.

[0080] To verify the aforementioned breakthrough, three different automotive tarpaulin materials were prepared using Comparative Examples 1 to 3, and various properties were tested for comparison. First, the commercial hydrophilic automotive tarpaulin material prepared using Comparative Example 1 was compared. Because it achieved hydrophilicity solely through hydrophilic acrylic resin without the addition of hydrophilic surfactants, its water contact angle was as high as 15.8°, failing to achieve superhydrophilicity. Consequently, it only possessed active self-cleaning properties for dust, but not for oil stains and bird droppings. Figure 3 It can be visually observed that when the oil stains on the surface of the commercial hydrophilic car tarpaulin material are actively self-cleaned by the water film formed by condensation (simulating frost in daily life), although some oil stains can be removed, a large portion of stubborn oil stains remain, resulting in a self-cleaning rate of only 34.7%, thus lacking active self-cleaning performance. In contrast, the long-lasting active self-cleaning car tarpaulin material prepared in Example 3 can completely remove surface oil stains. More importantly, because the commercial hydrophilic car tarpaulin material is not reinforced with hard calcium carbonate particles, its mechanical properties and service life are far inferior to those of the long-lasting active self-cleaning car tarpaulin material. Its hardness and elastic modulus are reduced by 69% and 70% respectively compared to Comparative Example 3, its abrasion resistance is reduced by 89%, and its outdoor service life is reduced by 88%.

[0081] Secondly, the superhydrophilic automotive tarpaulin material prepared by Comparative Example 2 was compared. It can be seen that, due to the addition of a hydrophilic surfactant, the water contact angle of the superhydrophilic automotive tarpaulin material prepared by Comparative Example 2 was significantly lower than that of Comparative Example 1 (8.1°), achieving superhydrophilicity, but still much higher than that of Examples 1 to 3. This is because it did not use amorphous calcium carbonate microparticles to load the hydrophilic surfactant, therefore only a small amount of surfactant was dispersed within it (…). Figure 4 a, 4.3%), while loading with amorphous calcium carbonate micron particles can significantly increase the surfactant content ( Figure 4 (b, 13.1%). Correspondingly, although the self-cleaning rate of oil stains and bird droppings (49.5% and 29.3%) of the superhydrophilic automotive tarpaulin material prepared in Comparative Example 2 was significantly improved compared with Comparative Example 1, it still could not achieve active self-cleaning of oil stains and bird droppings. In addition, since it was not reinforced by hard calcium carbonate particles, and the added hydrophilic surfactants hindered the cross-linking of PVC paste resin and reduced the mechanical properties of the resin itself, the mechanical properties, abrasion resistance, and outdoor service life of the entire superhydrophilic automotive tarpaulin material were further reduced compared with Comparative Example 1.

[0082] Finally, the active self-cleaning automotive tarpaulin material prepared in Comparative Example 3 was compared. It achieved excellent superhydrophilicity, active self-cleaning properties for dust, oil, and bird droppings by loading hydrophilic surfactants onto amorphous calcium carbonate microparticles. However, because the calcium carbonate microparticles were not hydrophilically activated and encapsulated in nanoparticles, the surfactant easily migrated and was lost. This led to a significant reduction in the mechanical properties of the automotive tarpaulin (hardness and elastic modulus decreased by 41% and 34% respectively compared to Example 3), weakened abrasion resistance (reduced by 74% compared to Example 3), and a significantly shortened outdoor service life of the automotive tarpaulin (reduced by 90% compared to Example 3).

[0083] Since the long-lasting active self-cleaning automotive tarpaulin material prepared in Example 3 has the best overall performance, it is used to compare and illustrate the role of each formulation and process in this application.

[0084] Example 4:

[0085] Compared with Example 3, this embodiment only changed the amount of dopamine hydrochloride added in step 1); the results are shown in Table 2:

[0086] Table 2

[0087]

[0088] Table 2 shows the mechanical properties, abrasion resistance, and outdoor service life of long-lasting self-cleaning automotive tarpaulin materials prepared with different amounts of dopamine hydrochloride. When the dopamine hydrochloride content is low (0.1 parts by mass), the anchoring effect of amorphous calcium carbonate microparticles on the hydrophilic surfactant is significantly weakened, leading to an increased proportion of surfactant migration into the interior of the automotive tarpaulin material, weakening mechanical properties (hardness and elastic modulus decreased by 30% and 24%, respectively), and correspondingly reducing abrasion resistance by 43%. Simultaneously, the easier the surfactant migrates, the more easily it is lost, thus reducing the outdoor service life by 65%. After 180 days of outdoor placement, the bird droppings self-cleaning rate of the automotive tarpaulin decreased by 41.1%, losing its active self-cleaning property. Figure 5 With increasing dopamine hydrochloride content, the anchoring effect of calcium carbonate particles on surfactants is enhanced, leading to continuous improvement in the mechanical properties, abrasion resistance, and outdoor service life of the automotive tarpaulin material. The threshold is reached at 0.4 parts by weight, at which point the overall performance of the automotive tarpaulin is optimal (e.g., ...). Figure 5The medium-to-long-term active self-cleaning automotive tarpaulin material retains excellent bird droppings self-cleaning properties even after 180 days of outdoor exposure. Further increasing the dosage of dopamine hydrochloride will occupy the loading vacancies of calcium carbonate, causing excessive surfactant overflow into the interior of the tarpaulin material, which will also reduce the material's mechanical properties, abrasion resistance, and outdoor service life. This weakening effect is significantly amplified when the dosage of dopamine hydrochloride exceeds 0.5 parts by weight (e.g., 0.8 parts by weight), including a 26% and 20% reduction in hardness and elastic modulus, a 37% reduction in abrasion resistance, and a 62% reduction in outdoor service life. Therefore, the optimal dosage of dopamine hydrochloride is 0.3-0.5 parts by weight.

[0089] Example 5:

[0090] Compared with Example 3, this embodiment only changes the amount of hydrophilic surfactant added in step 3); the results are shown in Table 3:

[0091] Table 3

[0092]

[0093] Figure 6 Table 3 shows the superhydrophilicity, active self-cleaning properties, mechanical properties, and abrasion resistance of long-lasting active self-cleaning automotive tarpaulin materials prepared with different amounts of hydrophilic surfactants. It can be observed that when the amount of hydrophilic surfactant added is low (0.1 parts by mass), the water contact angle of the automotive tarpaulin material increases significantly (9.7°); correspondingly, the self-cleaning rate of oil stains and bird droppings decreases drastically, resulting in the loss of active self-cleaning function. Figure 6 It can also be visually observed that oil stains on the material surface are difficult to remove. Because the automotive tarpaulin material contains relatively few surfactants, its hardness and elastic modulus are slightly increased to 0.57 GPa and 41.1 GPa, respectively. However, since its functionality is mainly contributed by surfactants, the low surfactant content actually reduces its abrasion resistance by 77%. With increasing surfactant content, the superhydrophilicity and active self-cleaning properties of the automotive tarpaulin material continuously improve, reaching a threshold at an addition amount of 0.7 parts by mass. At this point, the water contact angle is as low as 2.7°, and the self-cleaning rate of oil stains and bird droppings both reach 100%. Figure 6 This surfactant exhibits excellent superhydrophilicity and active self-cleaning properties. Furthermore, at this addition level, the surfactant has minimal impact on the mechanical properties of the automotive tarpaulin material, but significantly increases its abrasion resistance. Further increasing the addition amount does not improve the functionality of the automotive tarpaulin material; instead, it reduces its mechanical properties and abrasion resistance. Especially when the addition amount exceeds 1 part by weight (e.g., 1.5 parts by weight), the hardness and elastic modulus both decrease by 24%, and the abrasion resistance decreases by 49%. Therefore, the reasonable addition amount of hydrophilic surfactant is 0.5-1 part by weight.

[0094] Example 6:

[0095] Compared with Example 3, this embodiment only changes the amount of silica precursor added in step 5); the results are shown in Table 4.

[0096] Table 4

[0097]

[0098] Figure 7 Table 4 shows the hydrophilic surfactant leaching rate, superhydrophilicity, active self-cleaning properties, mechanical properties, and outdoor service life of long-lasting, actively self-cleaning automotive tarpaulin materials prepared with different amounts of silica precursor. The amount of silica precursor added determines the density and thickness of the silica particle encapsulation layer; the higher the amount added, the stronger the sealing effect on the surfactant, meaning it is more difficult for the surfactant to migrate out of the superhydrophilic microcapsules. Figure 7 Therefore, with the increase of silica precursor addition, the superhydrophilicity and active self-cleaning properties of automotive tarpaulin materials tend to decrease, while mechanical properties and outdoor service life tend to increase. However, it should be noted that when the silica precursor addition is too high (e.g., 2 parts by weight), its outdoor service life actually decreases by 96%. This is because the surfactant is completely encapsulated in hydrophilic microcapsules and cannot migrate to the surface of the automotive tarpaulin material to maintain functionality. Therefore, once the original surfactant on the surface of the automotive tarpaulin material is lost, functionality is rapidly lost. In summary, the reasonable range for silica precursor addition is 0.6-1.5 parts by weight.

[0099] Example 7:

[0100] Compared with Example 3, this embodiment only changes the amount of hydrophilic microcapsule powder added in step 7); the results are shown in Table 5.

[0101] Table 5

[0102]

[0103] Figure 8 Table 5 shows the superhydrophilicity, active self-cleaning properties, mechanical properties, and abrasion resistance of long-lasting active self-cleaning automotive tarpaulin materials prepared with different amounts of hydrophilic microcapsules. It can be observed that when the amount of hydrophilic microcapsules added is low (0.1 parts by mass), on the one hand, less hydrophilic surfactant is provided, leading to an increase in the water contact angle (14.3°) and a decrease in the active self-cleaning property of oil stains (36.5%); on the other hand, the reinforcing effect of the hard calcium carbonate particles is weakened, resulting in a decrease in hardness and elastic modulus of 54% and 29%, respectively, a decrease in abrasion resistance of 54%, and obvious surface damage after wear. Figure 8As the amount of hydrophilic microcapsules added increases, the superhydrophilicity, active self-cleaning properties, mechanical properties, and abrasion resistance of the automotive tarpaulin material all improve simultaneously. These four properties reach their optimal levels when the addition amount is 2 parts by weight. Further increasing the addition amount will, on the one hand, significantly increase the surface roughness of the automotive tarpaulin material, causing defects such as cracks and holes, and reducing superhydrophilicity and active self-cleaning properties; on the other hand, it will lead to an increase in surfactant content, reducing mechanical properties and abrasion resistance, especially when the addition amount exceeds 3 parts by weight (e.g., 4 parts by weight), where mechanical properties and abrasion resistance drop sharply. In summary, the reasonable addition amount of hydrophilic microcapsules is 1-3 parts by weight.

[0104] Example 8:

[0105] Compared with Example 3, this embodiment only changes the amount of PVC paste resin added in step 7); the results are shown in Table 6:

[0106] Table 6

[0107]

[0108] Table 6 shows the superhydrophilicity, active self-cleaning properties, mechanical properties, and abrasion resistance of long-lasting, actively self-cleaning automotive tarpaulin materials prepared with different amounts of PVC paste resin. It can be observed that the effect of the PVC paste resin addition amount is opposite to that of the hydrophilic microcapsule powder addition amount. This is mainly because when the addition amount is too small, it is insufficient to bind all the hydrophilic microcapsules, resulting in a loose surface structure and weak interfacial bonding of the automotive tarpaulin material, while also reducing the four properties listed in the table. When the addition amount is too high, the PVC paste resin over-coats the hydrophilic microcapsules, making it difficult for surfactants to migrate to the surface. Therefore, the superhydrophilicity and active self-cleaning properties are lost, and the proportion of rigid hydrophilic microcapsules decreases, weakening the mechanical property strengthening effect, thus reducing mechanical properties and abrasion resistance. In summary, the PVC paste resin addition amount needs to be within a moderate range, i.e., 3-8 parts by weight.

[0109] Example 9:

[0110] Compared with Example 3, this embodiment only changes the particle size of the amorphous calcium carbonate micron particles in step 1); the results are shown in Table 7:

[0111] Table 7

[0112]

[0113] Table 7 shows the superhydrophilicity, active self-cleaning properties, mechanical properties, and abrasion resistance of long-lasting active self-cleaning automotive tarpaulin materials prepared using amorphous calcium carbonate micron particles of different particle sizes. It can be observed that when the calcium carbonate particle size is relatively small (e.g., 1 μm), the loading of hydrophilic surfactants is significantly reduced due to the relatively small pore size and number of pores, resulting in a significant decrease in superhydrophilicity and active self-cleaning properties against oil stains. Simultaneously, based on the law of composite material mixing, it can be deduced that the elastic modulus of the composite material is positively correlated with the particle size of the hard particles, leading to a significant decrease in the hardness and elastic modulus of the automotive tarpaulin material, and a corresponding weakening of abrasion resistance. With the increase of calcium carbonate particle size, the surfactant loading and the strengthening effect on mechanical properties increase, thus simultaneously improving the superhydrophilicity, active self-cleaning properties, and abrasion resistance of the automotive tarpaulin material. The optimal overall performance is achieved at a particle size of 20 μm. While further increasing the particle size will not affect the mechanical properties of automotive tarpaulin materials, it will significantly increase surface roughness, causing water and oil to become trapped in the rough structure, reducing superhydrophilicity and active self-cleaning properties. The reduced abrasion resistance is due to the increased friction caused by the rough structure, accelerating the wear rate, especially when the particle size exceeds 30 μm (e.g., 50 μm). Therefore, the recommended particle size range for calcium carbonate is 5-30 μm.

[0114] Example 10:

[0115] Compared with Example 3, this embodiment only changes the amount of plasticizer / stabilizer added in step 7); the results are shown in Table 8:

[0116] Table 8

[0117]

[0118] Table 8 shows the superhydrophilicity, active self-cleaning properties, mechanical properties, and abrasion resistance of long-lasting, actively self-cleaning automotive tarpaulin materials prepared with different amounts of plasticizers or stabilizers. The main function of plasticizers or stabilizers is to enhance the dispersion of hydrophilic microcapsules in the coating and improve the stability of the coating. When the amount added is small or even absent, it easily leads to microcapsule aggregation, uneven dispersion, and a decrease in the degree of cross-linking of PVC paste resin, resulting in increased surface roughness and reduced mechanical properties of the automotive tarpaulin material, i.e., reduced superhydrophilicity, active self-cleaning properties, mechanical properties, and abrasion resistance. However, when the amount added is too high, because it lacks the hydrophilicity of surfactants, it will reduce superhydrophilicity and active self-cleaning properties. Furthermore, excessive free plasticizers / stabilizers can also hinder the cross-linking of PVC paste resin, thus reducing the mechanical properties and abrasion resistance of the automotive tarpaulin material. In summary, as an additive, plasticizers or stabilizers should not be added in too low a amount to have an optimizing effect, nor should they be added in too high a amount to affect the original properties of the automotive tarpaulin material. Therefore, a moderate value of 0.1-0.5 parts by weight is needed.

[0119] This invention discloses a long-lasting, active self-cleaning automotive tarpaulin material and its preparation method. The method includes hydrophilically activating amorphous calcium carbonate micron particles and loading them with a hydrophilic surfactant. Subsequently, silica nanoparticles are grown in situ on the surface of these micron particles to form superhydrophilic microcapsules. These superhydrophilic microcapsules are uniformly dispersed in PVC paste resin, and plasticizers and stabilizers are added. The mixture is then coated onto a polyester base fabric using a knife-coating process. After curing at room temperature, the long-lasting, active self-cleaning automotive tarpaulin material is obtained. This invention imparts superhydrophilicity to the coating by loading hydrophilic surfactants onto amorphous calcium carbonate micron particles with high specific surface area. The encapsulation with silica nanoparticles significantly delays surfactant loss, thereby achieving long-lasting active self-cleaning performance. Simultaneously, the addition of calcium carbonate particles can significantly enhance the mechanical properties of the automotive tarpaulin material and extend its service life.

[0120] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a long-lasting, active self-cleaning automotive tarpaulin material, characterized in that, Includes the following steps: Step 1) Add 0.3-0.5 parts by weight of dopamine hydrochloride to 30-50 parts by weight of deionized water, and mechanically stir for 5-10 minutes to completely dissolve the dopamine hydrochloride. Then add 1-3 parts by weight of amorphous calcium carbonate micron particles to the solution and keep stirring for 1-2 hours to disperse the particles evenly and obtain a calcium carbonate micron particle suspension. Step 2) The calcium carbonate micron particle suspension from Step 1) is dried in a low-temperature hollow environment at -30°C and 10 Pa for 24-36 h using freeze-drying technology to obtain hydrophilic activated calcium carbonate micron particles. Step 3) Redisperse 1-3 parts by weight of the hydrophilic activated calcium carbonate microparticles from Step 2) in 30-50 parts by weight of deionized water, add 0.5-1 parts by weight of hydrophilic surfactant during mechanical stirring, and continue stirring for 0.5-1 h to obtain a calcium carbonate microparticle suspension loaded with hydrophilic surfactant. Step 4) The calcium carbonate micron particle suspension loaded with hydrophilic surfactant from step 3) is freeze-dried again according to the method in step 2) to obtain calcium carbonate micron particles loaded with hydrophilic surfactant. Step 5) Disperse 1-3 parts by mass of calcium carbonate microparticles loaded with hydrophilic surfactant from step 4) into 80-100 parts by mass of deionized water, and mechanically stir until uniformly dispersed. Then, add 0.2-0.5 parts by mass of sodium hydroxide and 0.6-1.5 parts by mass of silica precursor in sequence, and stir and react at 50°C for 16-24 h to grow silica nanoparticles in situ on the surface of calcium carbonate microparticles loaded with hydrophilic surfactant, thereby obtaining a superhydrophilic microcapsule suspension. Step 6) Place the superhydrophilic microcapsule suspension from Step 5) in a 100 °C forced-air drying oven and dry for 6-8 h to obtain superhydrophilic microcapsule powder; Step 7) Add 1-3 parts by weight of the superhydrophilic microcapsule powder from Step 6) to 20-30 parts by weight of volatile organic solvent, then add 3-8 parts by weight of PVC paste resin, 0.1-0.5 parts by weight of plasticizer and 0.1-0.5 parts by weight of stabilizer in sequence. Stir mechanically for 1-2 hours to disperse and dissolve the components evenly. Finally, coat the polyester base fabric with a knife coating process and dry and cure at room temperature for 8-12 hours to obtain a long-lasting active self-cleaning automotive tarpaulin material.

2. The method for preparing a long-lasting, active self-cleaning automotive tarpaulin material according to claim 1, characterized in that, The amorphous calcium carbonate micron particles mentioned in step 1) are spherical particle aggregates with a particle size of 5-30 μm and a rough surface structure.

3. The method for preparing a long-lasting, active self-cleaning automotive tarpaulin material according to claim 1, characterized in that, The hydrophilic surfactant mentioned in step 3) is at least one of Chemours FS-31, FS-35 and FS-3100.

4. The method for preparing a long-lasting, active self-cleaning automotive tarpaulin material according to claim 1, characterized in that, The silica precursor mentioned in step 5) is at least one of tetraethyl orthosilicate, methyltrimethoxysilane, and methyltriethoxysilane.

5. The method for preparing a long-lasting, active self-cleaning automotive tarpaulin material according to claim 1, characterized in that, The volatile organic solvent mentioned in step 7) is at least one of acetone, ethanol and ethyl acetate, the plasticizer is at least one of trioctyl trimellitate, dibutyl phthalate and citrate, and the stabilizer is at least one of modified polyether, phosphite and calcium-zinc composite stabilizer.

6. A long-lasting, active self-cleaning automotive tarpaulin material, characterized in that, The long-lasting, active self-cleaning automotive tarpaulin material is prepared using any one of claims 1 to 5, and comprises: 1-3 parts by weight of amorphous calcium carbonate micron particles, 0.3-0.5 parts by weight of dopamine hydrochloride, 0.5-1 parts by weight of hydrophilic surfactant, 0.6-1.5 parts by weight of silica nanoparticles, 3-8 parts by weight of PVC paste resin, 0.1-0.5 parts by weight of plasticizer, and 0.1-0.5 parts by weight of stabilizer.

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