阅读说明：本技术 一种天然青石自清洁表面的制备方法 (Preparation method of natural bluestone self-cleaning surface ) 是由 段卓琦 谢再新 周豹 李汝恒 胡永茂 于 2020-06-10 设计创作，主要内容包括：本发明公开一种天然青石自清洁表面的制备方法,属于石材表面改性技术领域。本发明所述方法通过打磨抛光在天然青石表面形成微米粗糙结构,然后用聚多巴胺作为粘附剂将经过氟化的金属纳米颗粒粘附在青石表面,形成低表面能的微纳米复合结构,从而实现表面的自清洁性能。该方法制备的青石表面具有自清洁、抗腐蚀等特点。本发明提出的制备自清洁表面的方法设备工艺简单,成本低廉,绿色环保,有利于规模化生产。(The invention discloses a preparation method of a natural bluestone self-cleaning surface, belonging to the technical field of stone surface modification. According to the method, a micro rough structure is formed on the surface of natural cyan stone by grinding and polishing, and then fluorinated metal nano particles are adhered to the surface of the cyan stone by using polydopamine as an adhesive to form a low-surface-energy micro-nano composite structure, so that the self-cleaning performance of the surface is realized. The surface of the bluestone prepared by the method has the characteristics of self-cleaning, corrosion resistance and the like. The method for preparing the self-cleaning surface provided by the invention has the advantages of simple equipment and process, low cost, environmental protection and contribution to large-scale production.)

1. A preparation method of a natural bluestone self-cleaning surface is characterized by comprising the following steps:

(1) pretreatment: forming a micron structure on the surface of natural blue stone, removing dust, oil stain and organic matters on the surface, and drying for later use;

(2) formation of poly-dopamine adhesion layer: dissolving dopamine hydrochloride in a Tris-HCl solution to obtain a dopamine hydrochloride Tris-HCl solution, then placing pretreated natural bluestone in the dopamine hydrochloride Tris-HCl solution to be soaked away from light, taking out the bluestone, washing the bluestone with ultrapure water, removing redundant liquid on the surface of the bluestone, and drying the bluestone for later use;

(3) preparing an emulsion: mixing Al₂O₃Adding the nano particles into absolute ethyl alcohol to be uniformly dispersed to obtain emulsion A, and then mixing with Al₂O₃Adding perfluoroalkyl phosphoric acid with the same mass as nanoparticles into the emulsion A, and uniformly dispersing the perfluoroalkyl phosphoric acid in the emulsion A to obtain an emulsion B;

(4) formation of self-cleaning coating: and (3) putting the bluestone obtained in the step (2) into the emulsion B for soaking, taking out, washing with ultrapure water, removing redundant liquid on the surface of the blue stone, and drying to obtain the natural bluestone self-cleaning surface.

2. The method of making a natural cordierite self-cleaning surface as defined in claim 1, wherein: the pretreatment process in the step (1) is specifically as follows: the natural bluestone is sequentially adopted from 800 to 1600^#Grinding by using a grinding wheel, polishing by using a golden flannelette, wherein the polishing time is 60-90 min, the rotating speed is 80-160 r/min, ultrapure water is used as a polishing solution, and 10mL of liquid is added every 3 min; and then respectively ultrasonically cleaning the bluestone surface dust and the oil stain by using absolute ethyl alcohol and ultrapure water, and irradiating the bluestone surface dust and the oil stain by using ultraviolet light (UV) for 60-120 s to remove organic matter pollution on the surface of the bluestone.

3. The method of making a natural cordierite self-cleaning surface as defined in claim 1, wherein: the drying conditions in the step (1), (2) or (4) are as follows: drying for 24-36 h at 40 ℃.

4. The method of making a natural cordierite self-cleaning surface as defined in claim 1, wherein: in the step (2), the concentration of the dopamine hydrochloride in the dopamine hydrochloride Tris-HCl solution is 0.75-3 mg/mL.

5. The method of making a natural cordierite self-cleaning surface as defined in claim 1, wherein: the concentration of the Al2O3 nanoparticles and the concentration of the perfluoroalkyl phosphoric acid in the emulsion B in the step (3) are both 0.25-2 mg/mL.

Technical Field

The invention relates to a preparation method of a natural bluestone self-cleaning surface, belonging to the technical field of natural stone surface modification.

Background

The green stone has the characteristics of wear resistance, weather resistance and no radiation, is very environment-friendly, has huge natural storage and convenient material acquisition, is usually used for stone carving, home furnishing and outdoor buildings from ancient times and modern times, and is attractive and harmless to human. However, the pollution of acid rain and acid gas caused by the recent industrial development, water penetration and scouring are the main reasons for bringing the pollutants into the stone to cause the stone to be rotten and accelerate the stone to be differentiated and corroded; after rainwater permeates into the gaps of the stone, once the temperature is reduced to be below 0 ℃, water in the gaps is frozen and expanded, so that the stone is cracked, and the differentiation of the stone is accelerated; when the stone is used for home decoration, the stone is chemically damaged by household acidic cleaning liquid, strong acid and strong alkali in kitchens and toilets, so that the stone is very necessary to be effectively protected. The prior commonly used wax and polyacrylic acid stone protective agent has the defects of poor film forming and air permeability, short time effect and the like; the method for forming the self-cleaning protective layer on the solid surface by adding the metal oxide nano particles by taking hydrocarbons and alcohols as solvents has the problems of weak adhesion of the protective layer and the like due to lack of proper adhesive materials.

The self-cleaning surface is a surface having a water contact angle greater than 150 ° and a roll off angle less than 10 °. The construction of a self-cleaning surface requires two conditions: namely, the micro-nano rough structure and the low surface energy are provided. For natural stone, the surface is very rough, uneven and has large surface energy, and it is generally required to form a hydrophobic surface by coating a protective layer on the surface by a physical or chemical method or to construct a micro-nano rough structure with low surface energy on the surface to obtain self-cleaning property.

Patent CN107189656A discloses a preparation method of a wear-resistant self-cleaning coating based on polycarbonate, which uses polycarbonate glue as an adhesive, firstly coats a layer of polycarbonate glue on a substrate, then coats a solution for an intermediate layer on the glue, further coats a surface layer solution on the solution for the intermediate layer after the solution for the intermediate layer is dried, and obtains the wear-resistant self-cleaning coating after drying. The method needs multiple coating to obtain the self-cleaning coating, and uses toxic acetone as a solvent, so that the operation is complex and the method is not environment-friendly. US8147607 discloses that hydrocarbon and alcohol are used as solvent, nano-scale metal oxide is added to form sol, and the sol is coated on the solid surface to form a self-cleaning surface, but because no adhesive exists between the nano-particles and the solid surface, the self-cleaning coating is not firmly attached and has short time. Patent CN110204990A describes a water-soluble transparent self-cleaning coating suitable for cotton cloth, paper, stone, glass and other substrates, which is prepared from hydrophobic monomer a and hydrophilic monomer B under the action of initiator to form a polymer with a structural formula of hydrophobic monomer-random-hydrophilic monomer (P (a-r-B)) and fluorine-containing substance, and can form transparent self-cleaning surfaces on various substrate surfaces, but the aqueous solution of fluorinated P (a-r-B) microspheres needs to be dialyzed for many times before soaking the substrate, and there is no adhesive between the fluorinated microspheres and the substrate surface, which results in the problems of complicated operation and weak adhesion of the self-cleaning coating.

Disclosure of Invention

The invention aims to provide a preparation method of a natural cyan stone self-cleaning surface, which uses polydopamine as an adhesive, utilizes aluminum oxide nano-particles and perfluoroalkyl phosphoric acid to form a self-cleaning protective layer on a solid surface, can ensure the air permeability of stone materials and simultaneously has the functions of antifouling, self-cleaning, corrosion prevention and the like, and specifically comprises the following steps:

(1) pretreatment: forming a micron structure on the surface of the natural blue stone, removing dust, oil stain and organic matters on the surface, and drying for later use.

(2) Formation of poly-dopamine adhesion layer: dissolving dopamine hydrochloride in a Tris-HCl buffer solution to obtain a dopamine hydrochloride Tris-HCl solution, then placing the pretreated natural bluestone in the dopamine hydrochloride Tris-HCl solution, soaking for 24-36 h in the dark place, washing with ultrapure water, removing the redundant liquid on the surface of the bluestone, and drying for later use.

(3) Preparing an emulsion: mixing Al₂O₃Adding the nano particles into absolute ethyl alcohol to be uniformly dispersed to obtain emulsion A, and then mixing with Al₂O₃Adding perfluoroalkyl phosphoric acid (FPA) with the same mass as the nano particles into the emulsion A, and uniformly dispersing the perfluoroalkyl phosphoric acid in the emulsion A to obtain an emulsion B; in the dispersing process, after the ultrasonic dispersion is carried out for 50-90 min by adopting low frequency (28Hz, 5min) and high frequency (40Hz, 5min) alternately, the magnetic stirring is carried out for 2-4 h.

(4) Formation of self-cleaning coating: and (3) putting the bluestone obtained in the step (2) into the emulsion B, soaking for 24-36 h, taking out, washing with ultrapure water, removing redundant liquid on the surface of the green stone (spin-coating treatment by using a spin coater), and drying to obtain the natural bluestone self-cleaning surface.

Preferably, in step (1) of the present inventionThe pretreatment process specifically comprises the following steps: the natural bluestone is sequentially adopted from 800 to 1600^#Grinding by using a grinding wheel, polishing by using a golden flannelette, wherein the polishing time is 60-90 min, the rotating speed is 80-160 r/min, ultrapure water is used as a polishing solution, and 10mL of liquid is added every 3 min; and then respectively ultrasonically cleaning the bluestone surface dust and the oil stain by using absolute ethyl alcohol and ultrapure water, drying, and irradiating by using ultraviolet light (UV) for 60-120 s to remove organic matter pollution on the surface of the bluestone.

Preferably, the specific process of ultrasonic cleaning is as follows: ultrasonically cleaning in absolute ethyl alcohol at low frequency (28Hz, 5min) and high frequency (40Hz, 5min) for 10-20 min alternately, and then washing with ultrapure water for 3-5 times; and then putting the ultra-pure water into the ultra-pure water, alternately carrying out ultrasonic cleaning at a medium frequency (28Hz, 5min) and a high frequency (40Hz, 5min) for 10-20 min, then washing the ultra-pure water for 3-5 times, and repeating the steps of ultra-pure water ultrasonic cleaning and ultra-pure water washing for 2-3 times.

Preferably, the drying conditions in step (1), (2) or (4) of the present invention are: drying for 24-36 h at 40 ℃.

Preferably, in step (2) of the present invention, the concentration of dopamine hydrochloride in the dopamine hydrochloride Tris-HCl solution is 0.75-3 mg/mL, and the Tris-HCl buffer is commercially available Tris-HCl buffer with PH 9.

Preferably, Al is present in emulsion B in step (3) of the present invention₂O₃The concentration of the nano particles and the concentration of the perfluoroalkyl phosphoric acid are both 0.25-2 mg/mL.

The principle of the invention is as follows: FPA and Al in emulsion₂O₃And reacting to generate an R- (OH) (O) P-O-Al-group, wherein aluminum ions are chelated with poly dopamine and then firmly adhered to the surface of the bluestone, a hydrophobic group R is formed at the other end of the poly dopamine, a micro-nano rough structure with low surface energy is formed on the surface of the bluestone, and the construction of the micro-nano rough structure on the surface of the bluestone and the chemical modification with low surface energy are synchronously carried out.

The dopamine hydrochloride, the Tris-HCl solution and the perfluoroalkyl phosphoric acid used in the invention are all commercially available analytical purifiers.

The technical method provided by the invention has the following advantages:

(1) the invention adopts polydopamine to form an adhesive layer on the surface of bluestone, and FPA and Al are in emulsion₂O₃Reaction to formAnd the R- (OH) (O) P-O-Al-group, wherein aluminum ions are firmly adhered to the surface of the bluestone after being chelated with the poly dopamine, the hydrophobic group R is formed at the other end of the poly dopamine, a micro-nano rough structure with low surface energy is formed on the surface of the bluestone, the construction of the micro-nano rough structure on the surface of the bluestone and the chemical modification with low surface energy are synchronously carried out, and the preparation process of the self-cleaning bluestone surface is simplified.

(2) The method can prepare antifouling self-cleaning surfaces on the surfaces of the green stones with different sizes and shapes, and can prepare the self-cleaning cordierite surface with excellent antifouling self-cleaning performance, wherein the water contact angle of the surface is 165-170 DEG, and the lag angle is 17-22 DEG through process optimization.

(3) The method has the advantages of simple operation, low equipment requirement, low cost, non-toxic and pollution-free preparation process, contribution to large-scale production, excellent self-cleaning performance of the prepared surface and the like.

Drawings

FIG. 1 is an optical plot of the contact angle of the surface of self-cleaning cordierite with water prepared in example 1.

FIG. 2 is an optical plot of the contact angle of the surface of self-cleaning cordierite with water prepared in example 2.

FIG. 3 is an optical plot of the contact angle of the surface of self-cleaning cordierite with water prepared in example 3.

FIG. 4 is an optical plot of the contact angle of the surface of self-cleaning cordierite with water prepared in example 4.

Detailed Description

The invention will be described in more detail with reference to the following figures and examples, but the scope of the invention is not limited thereto.