CN1944348A - Method for preparing silicon dioxide anti-pollution layer of polished glazed tile surface - Google Patents

Abstract

The method of forming antifouling silica coating on the surface of polished glazed tile includes the following steps: preparing composite silica sol liquid; spreading the composite silica sol liquid to the surface of the polished glazed tile and polishing simultaneously to produce polishing, rolling, thinning and rubbing effect, so as to evaporate water and form bright antifouling silica coating; and further polishing while adding hydrophobic and lipophobic organic fluorosilicon compound solution to raise the antifouling effect.

Description

Preparation method of silicon dioxide anti-fouling coating on surface of polished ceramic tile

Technical Field

The invention relates to a coating method of an antifouling coating, in particular to a coating method of an antifouling coating for polished tiles and the like, which can be used for forming a compound antifouling coating based on silicon dioxide and having high gloss, firm combination, good decoration effect and high efficiency antifouling on the surface of a substrate such as polished tiles and the like.

Background

In the field of the production of ceramic polished tiles of the prior art, as a surface protection-finishing process after polishing, there has been an antifouling wax application process, commonly known as "waxing", which in fact has almost become the standard working step that the polished tiles must undergo. In the above-mentioned anti-fouling wax application process, commonly known as "waxing", liquid wax is applied to the surface of the tile at one time, and then polished by one or more felt grinding wheels, wherein the organic solvent in the applied liquid is volatilized during the polishing process to form a substantially uniform anti-fouling cleaning wax film on the entire surface of the tile; later, the material used in the method has new change, and the organic solution of some organic high molecular substances is developed to replace paraffin in liquid wax, and finally the corresponding organic high molecular polymer antifouling clean-keeping film is formed on the surface of theceramic tile. The products of the polishing and finishing process are paraffin or organic material films with functions similar to paraffin, and even the films have the defects of insufficient transparency, low hardness, poor wear resistance and the like; thus, such films have been considered temporary and, once constructed, after a predetermined "stage of construction anti-fouling function" has been accomplished, are cleaned to reveal the much better decorative effect inherent in the background surface of the polished tile. The main improvement of the invention to the method is that SiO-based is adopted₂Instead of the temporary antifouling coating film described above.

Chinese patent application (CN 1706560A) discloses a method for preparing a functional coating, which comprises the steps of doping a functional substance into an organic solution or a silicate solution to form a coating agent, coating the coating agent on the surface of a base material, polishing and grinding to remove the redundant coating agent, and enabling the coating agent to form a coating with a special function on the surface of the base material. The film-forming substance of this invention is a silica solution (claim 1), but those skilled in the art know that the effective concentration of the silica solution is often too low to be detected by the apparatus, which in fact determines the film-forming speed of the method in such a case, and even if it is considered to exist, it is too slow to satisfy the practical requirement in the industrial sense, thereby losing the industrial application sense. Also, this method requires polishing after the coating is dried, which significantly reduces the film-forming quality.

Disclosure of Invention

The invention provides a method for forming a silicon dioxide-based compound anti-fouling coating on a ceramicpolished tile and other substrates, which is characterized by firstly preparing a compound silica sol liquid based on silica sol, then applying the compound silica sol liquid to the surface of the ceramic polished tile to be processed, which is subjected to surface polishing, and forcing the compound silica sol liquid applied to the surface of the ceramic tile to be subjected to grinding and polishing treatment. Thereby forming the compound antifouling coating based on silicon dioxide. The above steps may be repeated until a desired thickness of the anti-fouling coating is obtained. The anti-fouling coating thickness is 0.01-100 μm, preferably 0.05-50 μm, more preferably 0.1-10 μm.

The invention also provides a method for forming the silicon dioxide-based compound anti-fouling coating on the base materials such as the ceramic polished tiles and the like, which is characterized in that the silicon dioxide-based compound anti-fouling coating is further treated by the fluorine-silicon organic compound with oleophobic and hydrophobic properties, specifically, the fluorine-silicon organic compound solution is coated on the surface of the silicon dioxide-based compound anti-fouling coating, and then the grinding and polishing treatment is carried out by the fluorine-silicon organic compound solution coated on the surface of the coating. Further improving the anti-fouling ability of the coating. For example, water repellency and oil repellency are improved.

The invention provides a method for forming a silicon dioxide-based compound anti-fouling coating on a ceramic polished tile and other substrates, wherein the compound silica sol liquid contains silica sol (namely the technology in the fieldSilica sol, commonly known by the people) and a coating colloid emulsion, wherein the solid phase content of the compound silica sol liquid is 0.1-20 wt%, preferably 1-15 wt%, more preferably 5-10 wt%; in the solid phase of the compound silica sol liquid, SiO isused₂The solid phase carried by the colloidal emulsion for coating is 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, more preferably 1 to 3 parts by weight, based on 100 parts by weight. The silica sol liquid may be commercially available or may be formulated in situ using methods well known to those skilled in the art.

The invention provides a method for forming a compound anti-fouling coating based on silicon dioxide on a substrate such as a porcelain polished tile, wherein the colloidal emulsion for the coating is selected from one or more of styrene-acrylic emulsion, ethylene-propylene emulsion, silicone-acrylic emulsion and fluorocarbon emulsion; the compound components of the four emulsions are respectively

① styrene-acrylic emulsion, which is a quaternary copolymer emulsion (trade name LT-1 emulsion) of styrene, butyl acrylate, methyl methacrylate and methacrylic acid, or a quaternary copolymer emulsion (trade name LT-2 emulsion) of ethyl acrylate instead of butyl acrylate in the above combination, or a ternary copolymer emulsion (trade name LT-3 emulsion) of styrene, ethyl acrylate and methacrylic acid, is a representative of the emulsion for coating of the so-called 1 st generation;

② ethylene-propylene emulsion is a copolymer emulsion of vinyl acetate and acrylic monomer, and is another representative of emulsion for coating of the 1 st generation;

③ Silicone acrylic emulsion, which is resin emulsion of acrylic ester monomer organic silicon functional group graft copolymerization, is a representative of emulsion for the second generation paint, has good waterproof function due to the hydrophobic property of the organic silicon functional group, and obviously improves the stain resistance after forming the film, and the comprehensive performance of the emulsion is obviously higher than that of the common emulsion for the first generation paint, such as the styrene-acrylic emulsion and the ethylene-propylene emulsion;

④ fluorocarbon emulsion comprises two kinds of emulsion including perfluorocarbon emulsion and fluorocarbon emulsion, the perfluorocarbon emulsion is perfluorocarbon polymer emulsion prepared through solution or emulsion polymerization of perfluoro monomer, such as tetrafluoroethylene, fluorocarbon emulsion is fluorocarbon polymer emulsion prepared through solution or emulsion polymerization of one or more kinds of fluoromonomers including tetrafluoroethylene, vinyl fluoride, chlorotrifluoroethylene, hexafluoropropylene and other non-fluoromonomers, such as ether or ester monomer containing vinyl (allyl) alkyl or aryl or unsaturated olefine acid, the fluorocarbon polymer has outstanding chemical inertia and very low surface energy due to the very high saturation of F-C covalent bond, and the fluorocarbon polymer emulsion has outstanding oleophobic, hydrophobic, waterproof, antisticking and antifouling performances after film forming.

The coating colloidal emulsions are either commercially available or can be formulated in situ using methods well known to those skilled in the art. The solvent used in the coating colloidal emulsion is an organic or inorganic solvent commonly used by those skilled in the art, and includes but is not limited to: all being water as the suspending medium.

The invention provides a method for forming a silicon dioxide-based compound anti-fouling coating on a ceramic polished tile and other substrates, wherein the used fluorosilicone organic compound is selected from one or more compounds with the following general formula:

①(R₁)₃Si(OSi(R_f)(R₂))_nO Si(R₁)₃

wherein n is an integer of 0 to 100; r₁Is a hydrocarbon group such as methyl, ethyl, propyl; r₂Is alkyl, hydroxyl, amino; r_fIs CF₃(CF₂)_p(CH₂)_qWherein p and q are integers of 0-20;

②CF₃(CF₂)_m(CH₂)_nSi(OM)₃

wherein M and n are integers of 0-20, and M is a hydrocarbon group such as methyl, ethyl, propyl; and

③CF₃(CF₂)_m(CH₂)_nSiCl_3-fR_f

wherein m and n are integers of 0-20, f is an integer of 0-3, R is chlorine, bromine or alkyl, such as chlorine, bromine, methyl, ethyl, propyl;

preferred fluorosilicone compounds are selected from HO (Si (CH)₃)(CF₃(CH₂)₂)O)_nH、CF₃(CF₂)₇Si(OCH₃)₃、CF₃(CF₂)₇SiCl₃One or more of (a).

The solvent or dispersion medium for the fluorosilicone organic compound is selected from alcohols, benzenes, ethers, and hydrocarbons.

The present invention also provides a silica-based compound antifouling coating prepared according to any of the above methods. The invention also provides a ceramic polished tile with the compound anti-fouling coating.

Detailed Description

The silica sol adopted by the invention can be any form of silica sol sold on the market at present, and the invention has no special limitation on the concentration, purity, average diameter and particle size distribution of silica colloid particles in the used commercially available silica sol, but a stable storage period meeting the practicability is ensured; SiO in the solution of silica sol is preferred₂The content is 5-65 wt%, and SiO in silica sol is more preferable₂The content is 20-45 wt%.

The acid-base property of the commercially available silica sol solution used in the present invention is not particularly limited as long as the colloidal state stability of the sol during storage until use can be ensured.

Table 1 shows the product series parameters of Shanghai applied physical research institute of China academy of sciences in the silica sol section.

TABLE 1 introduction of parameters of the silica sol product series

(data source: introduction of silica sol department of Shanghai applied physical research institute of Chinese academy of sciences)

№	SiO2Content (wt.) Wt％	pH value	Range of particle diameter nm	Remarks for note
					1	20 or 25	2-4	10-30	Acidic silica sol
2	20 or 25 or 30	6.5-7.5	10-20	Neutral silica sol
					3	40 or 50	9.0-10.0	20-30 40-60 70-100	Basic property High concentration Silica sol
4	40	9.0-10.0	40-60 70-100	Basic property Large particle size Silica sol
					5	30-40	9.0-10.0	80-120	Silica sol special for alkaline large-particle polishing

It is known that silica sol has different zeta potentials characterizing the electric double layer structure of colloidal particles and different colloidal state stabilities under different pH values. The following cites another manufacturer's silica sol product parameters, wherein the data of the useful life indicates that the useful life of the alkaline silica sol is twice as long as the acidic one, indicating that the stability of the alkaline silica sol is significantly greater than the acidic one; however, for the present invention, the requirements of the actual use period can be met, and the details are shown in table 2:

TABLE 2 introduction of parameters of another series of silica sol products given by a manufacturer

(data source: introduction of Qingdao Hengshengda chemical Co., Ltd.)

Item	Alkaline sodium form				Acidic non-stabilized dosage forms			Typical values
										JN-20	JN-25	JN-30	JN-40	SW-20	SW-25	SW-30	JN-30	SW-25
	SiO2 Content (wt.) Wt％	20.0-21.0	25.0-26.0	30.0-31.0	40.0-41.0	20.0-21.0	25.0-26.0	30.0-31.0	30.3										25.6
Na2O Content (wt.) Wt％≤										0.30	0.30	0.03	0.40	0.04	0.05	0.06	0.25	0.04
	pH value	8.5-10.	8.5-10.0	8.5-10.	9.0	2.0-4.0	2.0-4.0	2.0-4.0	9.6										2.8
Average particle diameter nm										10-20	10-20	10-20	10-20	10-20	10-20	10-20	11	10
	Period of validity	Alkaline for one year and acidic for half a year
Package (I)											25Kg plastic bucket or 250Kg plastic bucket.
	Storage and transportation conditions	Keeping at 0-40 deg.C during storage and transportation to prevent freezing or insolation.

Most commercial silica sols are alkaline, and the silica sols are characterized in that the pH range with good stability is 8.5-10.0 in the alkaline region; the colloidal stability in the region of the larger pH value is deteriorated, when the pH value is adjusted by NaOH, the pH value is adjusted to be more than 10.5, particularly 11, and then the pH value is adjusted by Na⁺Increase in concentration of (A), Na⁺The electrolyte has obvious gel decomposition effect, promotes gelation and leads the colloid to lose stability; when the pH value reaches 12, Na with the modulus of 5 is correspondingly entered₂O·5SiO₂Range of water glass composition, and Na₂O·5SiO₂When the water is not dissolved, gel is generated; in the acidic region, silica sols are less stable than the basic regions described above, and acidic commercial silica sols can be found which have a pH of from 2.0 to 4.0 and, at a pH of from 5 to 6, silica sols are obtainedThe glue gels most easily (several hours).

In light of the above comparison regarding colloidal stability of silica sols, it is preferred to use basic silica sols, although commercial silica sols are in principle commercially available in all aspects of acidity, neutrality and basicity.

The silica sols used according to the invention can also be formulated in situ. If the preparation is carried out on site, the stability can meet the production requirement for only a few hours.

In the compound silica sol liquid based on silica sol, the additive used as the compound component is the conventional and general colloidal emulsion for the coating in the existing coating industry: this is a collective general term, which is a water-based colloidal dispersion system obtained by emulsion polymerization of various related organic polymer unsaturated compound monomers. Document [1]]The modifying function of the polymer in the polymer cement-based composite material is discussed, namely the effect that the polymer has plasticizing, toughening … rheological auxiliary agent and the function of reducing the friction coefficient between internal particles … in the cement matrix. Without being limited by any theory, the invention adopts the emulsion to exert the functions of the emulsion in the grinding and polishing process to properly improve the lubricity of the compound silica sol system and adjust the gelation kinetic property of the sol → gel → dry glue change process in the film forming process of the system: thereby on one hand, the temperature uniformity of grinding, polishing and friction heating on the surface of the ceramic tile is favorably controlled, which has great significance for improving the reaction uniformity of the gel-dry glue film layer in the forming process; on the other hand, the dehydration-gelation change speed, the toughness of the gelation reaction product and the plastic deformability under the actions of grinding, polishing, extruding and shearing in the gelation process of the sol → gel → dry glue can be properly adjusted, the thickness uniformity of the film in formation is improved and promoted, the formation probability and concentration of fine defects are avoided or reduced, and finally formed SiO is endowed₂The base compound anti-fouling coating film has excellent toughness, smoothness and improved compactness; the dosage of the coating emulsion contained in the compound silica sol liquid based on the silica sol is that the silica sol contained in the compound silica sol liquidSiO of (2)₂The weight share of the dispersed phase in the colloidal emulsion for the coating is not more than 10 parts, preferably not more than 5 parts, for 100 parts by weight; more preferably less than 1 part; with respect to such an emulsion as a collective generic term, the kinds thereof include:

styrene-acrylic emulsion: styrene, butyl acrylate, methyl methacrylate and methacrylic acid quaternary copolymer emulsion (trade name LT-1 emulsion), or quaternary copolymer emulsion (trade name LT-2 emulsion) of ethyl acrylate instead of butyl acrylate in the above combination, or styrene, ethyl acrylate and methacrylic acid ternary copolymer emulsion (tradename LT-3 emulsion) is a representative of emulsion for coating of so-called generation 1; the styrene-acrylic emulsion is a milky white liquid, has a solid content of 1-55%, a pH of 5-10, a viscosity (25 +/-1 ℃) of 500-5000 mPa.S, a Minimum Film Forming Temperature (MFFT) of 10-25 ℃ and a glass transition temperature (Tg) of 10-35 ℃. Table 3 is an example of a commercial styrene-acrylic emulsion:

TABLE 3S-01 styrene-acrylic emulsion

(Nantong shengda chemical industry Co., Ltd. product technical data)

Item	Index (I)	Item	Index (I)
				Appearance of the product	Opalescent blue light liquid	Solid content (wt%)	48±2
Minimum film formation temperature (MFFT)	14-23℃	Viscosity (mPa.s)	600-1500
				PH value (PH value)	7.5-9.0	Residual monomer (bromine number%)	≤1.0
Stability in dilution	20% aqueous solution through	Chemical stability (5% calcium chloride emulsion)	1: 5 without deterioration such as flocculation and the like Phenomenon(s)
				Mechanical stability	3000r/min Half an hour of passing	Freeze thaw stability	5 circulation pass through

Another example of the styrene-acrylic emulsion is BC-01 styrene-acrylic emulsion produced by Shandongboda chemical Co., Ltd, and the product performance indexes are as follows:

appearance: a milky white liquid; viscosity: 100 to 1000 mPas;

minimum Film Formation Temperature (MFFT): 23 +/-1 ℃; pH value: 7.0 to 9.0;

solid content: 45 +/-2%; glass transition temperature (Tg deg.C): at 25 ℃.

② ethylene-propylene emulsion, which is a copolymer emulsion of vinyl acetate and acrylic monomer and is another representative of emulsion for coating of the 1 st generation, is a milky white liquid, has a solid content of 1-60%, a viscosity (25 + -1 ℃) of 500-2500mPa&s, a pH (25 ℃) of 5-10, a Minimum Film Forming Temperature (MFFT) of 10-30 ℃, and a glass transition temperature (Tg) of 10-35 ℃, and is shown in Table 4, wherein Table 5 shows two examples of commercial styrene-acrylic emulsion:

TABLE 4 XL-3000 ethylene-propylene emulsion

(New Yu of Shang City, chemical industry Co., Ltd. product technical data)

Serial number	Item	Index (I)
			1	Appearance of the product	Milky white micro-strip blue phase liquid
2	Solids content, WT%	55±2％
			3	Viscosity, mpa.s	1000-2500
4	Glass transition temperature,. degree.C	28
			5	Minimum film Forming temperature deg.C	16
6	Average particle diameter μm	0.3-0.5
			7	Ionic property	Anion(s)

TABLE 5 LE-8408 ethylene-propylene emulsion

(Jiangsu Li Wenzhi chemical company, Inc. product technical data)

Serial number	Item	Index (I)	Detection method
				1	Appearance of the product	Milky white liquid	Visual inspection of
2	Viscosity (23 ℃. + -. 1 ℃) mPa.s	1000-3000	GB/T2794
				3	Solids content%	53.0-55.0	GB/T1725
4	pH value	3-5	Enterprise standard
				5	Glass transition temperature of	28	Calculated value
6	Minimum film Forming temperature deg.C	16	GB/T9267
				7	Ion property	Anion(s)
8	The g/L of volatile organic compounds is less than or equal to	30	GB18582-2001 appendix A
				9	Free formaldehyde g/kg is less than or equal to	0.08	GB18582-2001 appendix B

③ Silicone-acrylic emulsion, which is a resin emulsion of graft copolymerization of acrylate monomer and organosilicon functional group, is a representative emulsion for the second generation coating, has good waterproof function due to the hydrophobic property of organosilicon functional group, and the stain resistance after film forming is obviously improved, the comprehensive performance of the emulsion is obviously higher than that of the common emulsion for the first generation coating (such as the above-mentioned styrene-acrylic emulsion and ethylene-propylene emulsion), the silicone-acrylic emulsion is milky white liquid, has a pH value (25 ℃) of 5-10, a viscosity (25 +/-1 ℃) of 100-5000 mPa.s, a solid content of 1-50%, a Minimum Film Forming Temperature (MFFT) of 10-25 ℃, and a glass transition temperature (Tg) of 10-35 ℃, and table 6 is a more specific example of a commercial silicone-acrylic emulsion as follows:

TABLE 6 SD-528 Silicone-acrylate emulsion

(Nantong shengda chemical industry Co., Ltd. product technical data)

Item	Index (I)	Item	Index (I)
				Appearance of the product	Milky bluish liquid	Solid content (wt%)	45±2
Minimum film formation temperature (MFFT)	15-20℃	Viscosity (mPa.s)	500-1000
				PH value (PH value)	8.0-9.5	Residual monomer (bromine number%)	≤1.0
Stability in dilution	20% aqueous solution through	Chemical stability (5% calcium chloride emulsion)	1: 1 by
				Mechanical stability	4000r/min Half an hour of passing	Freeze thaw stability	5 circulation pass through

Another commercial example of silicone-acrylic emulsion is Shanghai Yisheng trade development Co., Ltd.product ES-J0307S silicone-acrylic emulsion:

the main components are as follows: a silicone acrylate copolymer; appearance: a milky white liquid; viscosity (cps): 250 of (a); pH: 7.0-9.0; tg: 35 ℃; minimum film formation temperature: 30 ℃; solid parts (%): 46 +/-1.

④ fluorocarbon emulsion includes two kinds of emulsion including perfluorocarbon emulsion and fluorocarbon emulsion, the perfluorocarbon emulsion is perfluorocarbon polymer emulsion prepared through solution or emulsion polymerization of perfluoro monomer, such as tetrafluoroethylene, fluorocarbon emulsion is fluorocarbon polymer emulsion prepared through solution or emulsion polymerization of one or several kinds of fluoromonomer, such as tetrafluoroethylene, vinyl fluoride, chlorotrifluoroethylene, hexafluoropropylene and other non-fluoromonomer, including vinyl (allyl) alkyl, aryl ether or unsaturated olefine acid, etc. the fluorocarbon polymer has outstanding chemical inertia and very low surface energy owing to the very high saturation of F-C covalent bond, and the fluorocarbon polymer emulsion has outstanding oleophobic, hydrophobic, waterproof, antisticking and antifouling performance.

The most common perfluorocarbon emulsions are polytetrafluoroethylene aqueous dispersion emulsions, trade name polytetrafluoroethylene concentrated dispersions, and the like. An example of a product series of aqueous polytetrafluoroethylene dispersion emulsions is shown in Table 7.

TABLE 7 aqueous dispersion of PTFE emulsion for SFN-1, SFN-3, SFN-A, SFN-5A

(Zhonghao Chenguang chemical research institute product technology data)

	SFN-1	SFN-3	SFN-A	SFN-5A
					Kinematic viscosity mm2/s	6～14
pH value	8～10
					Content of PTFE%	58～63	58～63	53～58	58～63
Density g/cm3	1.48～1.53	1.48～1.53	1.43～1.48	1.48～1.53
					Content of emulsifier%	6±2

The fluorocarbon emulsion is milky white liquid, has a solid content of 1-50%, a pH value of 5-10, a viscosity (25 +/-1 ℃) of 100-5000 mPa.S, a Minimum Film Forming Temperature (MFFT) of 10-25 ℃ and a glass transition temperature (Tg) of 10-30 ℃. Two commercial examples of fluorocarbon emulsions:

one is SKFT-I aqueous fluorocarbon emulsion which is a product of Beijing initiative nanotechnology Limited company, and has the following performance indexes:

milky white liquid in appearance; the pH value is 7-9; solid content is 45 +/-1%; viscosity (T-4) of 10-20 ″ in seconds

A charge performance anion; the minimum film forming temperature is 15 ℃.

The other is (F-117 fluorocarbon emulsion, a product of Beijing Oriental science and industry Co., Ltd, has performance indexes of 47% + -1 solid content, 7.5-9.0 pH value, 800-, slowly pouring themixture into a stirring device, and after the emulsion is completely added, continuously stirring for 30-40 minutes, and finishing the mixing operation; then transferring the compounded compound silica sol into a plastic container for packaging, and preferably standing and storing for 12 hours before use as a colloid aging and homogenizing period; in general literature concerning nano colloidal solutions, a "standing overnight aging homogenization period" is often left for the preparation of nano-sized colloids, because compared with a general chemical reaction aqueous solution system, a colloid system has a possible secondary aggregation structure of colloid particles and a large viscosity, so that the equilibrium state of the whole colloid system needs much longer time to reach: the factors include the factors of transition of the secondary colloidal particle agglomeration structure to an equilibrium state, hydration layers of the colloidal particle, corresponding electric double layer structures, and equilibrium process factors of distribution of the dispersing agent/suspending agent therein. For the preparation of the compound silica sol, a factor to be concerned is the requirement of pH value matching, namely the pH value of the blended silica sol used as a raw material and the colloidal emulsion for the coating which is conventional and commonly used in the coating industry can maintain the stability of the whole colloidal system; this aspect generally does not create any problems, and when evidence of dispergation is perceived, if a new combination of raw materials is not selected to meet the pH matching requirements, the pH should be adjusted to try to reverse the situation: the pH regulator may be selected from known pH regulators including acids, bases or salts or solutions thereof, and may be organic or inorganic. Preferably, acetic acid or concentrated ammonia is used. However, the use of soluble acidic or alkaline electrolytes containing high-valent cations should be avoided, since this often leads to destruction of the double layer structure of the micelle, destruction of the suspension stability and "accidental" dispergation; it is generally considered that the pH of the system obtained after mixing is adjusted in the direction of the pH range corresponding to the starting silica sol as a raw material, and this is a relatively easy and successful approach.

The method for applying the silica sol compound silica sol liquid to the surface of the ceramic tile to be processed can use any method commonly used in the existing industry: such as atomization spraying, liquid curtain flow coating, rotation-centrifugal spin coating, brush coating, roll coating, or blade coating, and less frequently employed drip coating or brush coating in a line; however, the elimination of the liquid supply by injection of cooling water from the center of the grinding head, which is the standard method in the field of stone polishing and ceramic tile polishing, is common, because both the silica sol and the compound silica sol prepared as stated above have a tendency to harden by itself (forming a so-called "crusty") in contact with carbon dioxide in the air, and the compound silica sol is supplied by injecting cooling water through the hollow channels in the center shaft of the grinding head from the high position downwards, which makes it extremely difficult to remove the "crusty" inside the channels, thus causing a series of problems of operational quality and reducing the surface gloss uniformity and the compact antifouling efficacy of the final product, a compound film based on silica.

Regarding the ceramic polished tile to be subjected to film coating processing, in order to finally achieve the surface antifouling film with high quality, the tile needs to be well fired in advance to enable the water absorption rate to reach the ceramic tile grade requirement, namely the water absorption rate is less than or equal to 0.5%, and the surfaceof the tile is well polished before, so that the surface gloss reaches 60, preferably 65 gloss units, and it is worth pointing out that most of the polished tiles sold in the market actually have only 50-55 gloss units; therefore, the parameters essentially require that the sintering residual porosity and the pore diameter of the surface of the ceramic brick to be processed are small and the surface roughness is low, and when the parameters are met, the method of the embodiment of the invention can obtain the good effect that the surface of the obtained product brick can reach 90 gloss units or even higher. And the antifouling property reaches 4 grades and 5 grades of the highest grade according to detection method detection of GB/T3810.14-1999. If the water absorption and the surface-polished glossiness of the tile as a substrate do not meet the requirements of the parameters, the glossiness and the anti-fouling performance of the corresponding final product are also reduced correspondingly.

Without being limited by any theory, the compound antifouling film based on silicon dioxide is essentially a dry glue film which is doped and modified by organic polymer compound emulsion and contains a large amount of nano-scale microscopic pores, and the dry glue film essentially still belongs to the same structure and form as the drying agent allochroic silicagel in a dryer of a common chemical laboratory, but is only dispersed and mixed with some impurities intentionally added in the process, including corresponding organic matters contained in the organic polymer compound emulsion, dispersing agents and suspending agents and other colloid stabilizing agents added in the preparation process of commercial silicasol; such a dry colloidal film exhibits changed physicochemical properties due to the inclusion of the dopant, for example, when the organic polymer emulsion is a silicone-acrylic emulsion, the film exhibits strong hydrophobic properties.

About the chemical synthesis of SiO nanoparticles₂Comparing and screening the process route between the colloidal slurry prepared from the powder and the silica sol of the nano colloidal particle. It is worth noting that in the early development stage of the present invention, two silica sol process routes containing nano-sized colloidal particles have been compared: the first is the direct blending of commercially available powdered fumed nanosilica with water to make a water-based colloid, and the second is a silica sol containing nano-sized particle colloidal particles (trade name is conventionally known as silica sol) as described above. Through experiments, the first route is to prepare nano SiO in gas phase₂The preparation of the powder with water into a stable colloidal suspension dispersion is easy, which is advantageous to a large extent in that, like all powdery nano-oxide particles, the surface of the commercial nano-particles has been treated with a good dispersant in order to prevent the strong agglomeration of the nano-particles, and the gas phase nano-SiO₂Powders, for example, ensure the stability of the colloidal systems described above. However, when the contamination preventive film test described above was carried out in a manner referred to simply as "coating and polishing are alternated plural times" as described below, the SiO in the first route was carried out under the same conditions₂The colloid is clearly inferior to the silica sol of the second route: the main differences are three points, one is that the speed from film forming to polishing to smooth and bright dry glue film is obviously inferior to that of the second route, the first route needs about 20-30 times of coating and polishing alternation, and the second route is greatly shortened, and about less than 15, even 6 or 7 times of coating and polishing alternation "The period is sufficient, and the second is that even if so,the final product surface of the first route isinferior in smoothness, glossiness to the antifouling property, respectively, to the second route; apparently, this is because of the gas phase of nano SiO₂The dispersant on the powder surface can hinder the merging and aggregation function of colloid particles, and also can hinder the reaction speed of molten gel → gel in the preparation process, and the final film-forming density is low; thirdly, a phenomenon is worthy of attention, namely dry glue clusters filled in needle-point-shaped pinholes (far larger than 'pores' which can only be just seen in common dense hemp) on the surface of the ceramic tile are obviously loosened in the first route, and the sharp corners processed by hard paper sheets can be picked out; on the occasion of the second route, the plugging can not be selected and is much firmer; the comparison of the bonding strength in terms of pore and pinhole plugging is more indicative of the problem through the observation of simply "natural drying after coating" on the tile surface: the dry glue film layer obtained in the first route can not be called as a film simply and straightly, the appearance is only like that a thin layer is loosely laid together, the substrate ceramic tile can be blown off by blowing air at a mouth, and the dry glue film layer in the second route can be wiped off by only slightly applying force to the finger although the dry glue film layer has a certain strength; finally, the cost of the first route is economically much higher than the second route; therefore, the best route for the process performance and process objectives of the present invention is to use commercially available silica sols rather than gas phase nano-SiO₂The powder serves as a basic starting material.

The following discusses, one by one, the operational characteristics of the preparation method of the compound antifouling thin film coating based on silicon dioxide of the present invention and the problems of influence and control of factors such as concentration, temperature, etc. in the preparation process.

The coating operation and the polishing operation are performed alternately for a plurality of times, that is, repeatedly performed according to a plurality of cycles of "application-polishing- …", and include the following changes:

A) the compound silica sol liquid is applied to a proper position on the surface of the ceramic tile in a proper amount, and usually the compound silica sol liquid can meet the requirement only by dripping in a dripping shape or brushing in a linear shape on the proper position on the surface of the ceramic tile,

B) in the case of a hand-held portable polisher, the plurality of alternating cycles are carried out by progressively sweeping the abrading head across the surface of the monolithic tile to be processed with the hand-held polisher of the type such as progressively sweeping the surface in a cyclical sequence of transverse-longitudinal-transverse-longitudinal … with appropriate overlap in the time sequence of the stroke width of each pass with the stroke trajectory of the immediately preceding pass,

C) during the movement, the compound silica sol liquid which is dripped or brushed on the surface of the ceramic tile to be processed in a line shape is uniformly distributed on the whole surface of the ceramic tile (and redundant compound silica sol liquid is thrown away) by a series of physical and chemical changes such as 'free water evaporation and sol-gelation' under the actions of grinding and spreading, polishing, friction heating and the like generated by a grinding head, and forms a 'gel state film which is in a proper viscous or flexible or nearly dry and hard state', wherein three points A), B) and C) form an operation circulating unit (or period) of the invention;

D) the gel-state film described in point C) is not allowed to dry completely and harden, and then the cycle is repeated again, i.e., all of the above-described points A), B) and C) are repeated.

And repeatedly circulating for many times in the manner of the above, specifically, several times, even one or twenty times, so as to prepare the compound antifouling film based on silicon dioxide. The principle that the coating operation and the polishing operation are alternately carried out for multiple times can be simply called as the principle that coating and polishing are alternately carried out for multiple times.

In fact, the environmental temperature, the temperature change, the pressure change, the rolling deformation process characteristic change, the concentration change along with the progress and other details, the colloid chemical series change and the rheological characteristic change in each operation period and among each other, and the like which are experienced by the compound silica sol under the specific concentration condition in the circulation process of the '… A), B), C) …' cannot have the strict controllability as that in a reaction beaker or a chemical reaction device, and can only be repeated or controlled in a rough range, so that the circulation times of the 'coating-polishing- …' process cannot be simply specified, but the practice proves that the proper operation condition cannot be determined by the proper test trial method, and the proper process parameter and the specific operation rule can not be found by the test trial method under the operation condition and the operation rule can not be established by the clear test trial method And (4) carrying out the following steps.

The invention aims to overcome the obvious defect of quite poor film-forming property of the silica sol by determining the principle of' coating and polishing for multiple times and alternately₂In the immersion-lifting mode of sol liquid, sol-gel coating method, the formed SiO₂The dry adhesive film is rigid and brittle, and if the film layer is slightly thicker, the difference in expansion coefficient from the substrate cannot be overcome, and cracking is easily caused during drying, for example, in document 2]Based on the research of preparing oxide thin film by systematic summary of ' sol-gel method ', the last statement is that ' … may increase the thickness of the film a little by methods such as incorporating additives into … and using multiple coatings (specifically, 1 st plating of 1 st dry glue film, sintering, 2 nd plating of 2 nd dry glue film, and so on-the way of plating-the cite), but it is still difficult to produce a film with a thickness greater than 0.5 μm. That is, the thickness of the coating layer as the final product of each coating process is in the range of 0.01 or 0.01 to 0.2 μm, which is obviously too thin for the purpose of a protective coating of the surface of the tile against contamination; the invention also makes it possible to observe in tests that, on ceramic tile substrates, the commercial silica sol is used in a simple manner "coating evenly over the entire surface → after drying of the coating liquid → polishing"In this way, the coating film is likely to crack after drying and even to roll up by itself, and even if no cracks are observed in some cases, the coating film is wiped off with a slight force by fingers, and even if the coating film is not wiped off, the coating film is carefully worked with the greatest effortAnd (3) performing grinding and polishing operation, so that a great part of the film layer is scattered and lost in the subsequent grinding and polishing process, and no dry glue is remained on the surface except for the residual film layer which is filled in pores and fine pinholes on the surface of the ceramic tile. Can be said that document [3]]The discussion can give a reasonable explanation of this: "the silica sol solid content of … industrial productis very low, generally 20-28%, … brings a large amount of moisture to the coating, thus leading to … drying shrinkage too big and shrinkage cracking". It can be said that SiO thus obtained is obtained for the same reason₂The dry glue film is too loose and therefore does not actually have the possibility of being able to be ground and polished at all, and certainly does not talk about antifouling properties. It is particularly emphasized that the film formation process described in point C) above is carried out at grinding head pressure (either from the arm of the operator or from the own weight of the grinding head and the mechanical pressure of the cylinder pressurization system of the longitudinal axis of the grinding head when the polishing machine is activated), which of course significantly contributes to the greatly improved compactness of the film formed under such conditions, enabling the desired good anti-fouling properties to be obtained; in a "functional coating preparation method" disclosed in chinese patent application (CN 1706560a), "… is … after the coating is dried and is polished … (P5, lines 1 and 2)" the drying-film forming and hardening process of the coating is a natural drying process completely without any pressure; from this point, it is more clearly shown that the sol-gel reaction can bear the external force of accelerating densification during the hardening film-forming process, which is an important technical improvement made by the present invention. In addition, the principle of 'coating and polishing for multiple times and alternately' developed by the invention can also increase the thickness of the final product, namely the compound antifouling film coating based on silicon dioxide: because the coating-grinding-polishing operation mode has the effects of grinding, grinding and polishing and the like generated by the grinding head, the gel film formed in the next period can be well and tightly combined with the gel film formed in the previous period to form a thickened integral film layer structure in the process of coating and polishing for multiple times in an alternating process.

It should be noted that the operation process of the "coating and throwing multiple alternation" principle described in the above points a), B), C), D) is not unique, and there is a general thought that it is endeavored to make the final product, i.e. the silica-based compound antifouling film coating, denser and thicker, and in the "coating and throwing multiple alternation" principle, it should be focused on the coordination matching between the "D) step and the steps B) + C), i.e. when starting the step D), the gel state film in the appropriate viscous and flexible state formed in the immediately previous step B) + C) is traced back, and the" soft and hard "state thereof needs to be adjusted and controlled to a more appropriate degree.

For example, instead of cycling the "… A), B), C), …" cycle as described above, such as but not limited to cycle 1, the compound silica sol liquid is applied once: this may be the application of said compound silica sol liquid to several different parts of the surface of said same tile simultaneously or successively, and it is not necessary to apply said compound silica sol liquid to each of said cycles in said cycle, for example but not limited to, inserting one or more "open grinding and polishing" operations after one or more of said cycles, i.e. the application of said compound silica sol is not performed during one cycle, but only said grinding head is continued to "open run" or more than one "over the whole surface of said tile or in a local position thereof, which is effective to further obtain a better polishing process and a harder, smoother shine as appropriate for the gel state film in a suitably viscous and pliable state formed during the previous B) + C) pass, or just to correct defects (e.g., wear scar details, see below) in the surface film state of the process, and then subsequently proceed to the "a" and "step operation" of the next cycle based thereon.

The concentration of the complex silica sol, and the temperatures experienced during the various cycles of the "… A), B), C), …" cycle workflow described above, also need to be adjusted appropriately.

First, concentration factors are of concern: the requirement that the water absorption rate of the ceramic tile serving as a substrate is less than or equal to 0.5% is specified, and further explained herein, on the basis of the above, according to the difference between the sintering degree and the sintering state of the ceramic tile, especially the difference of the observed pore rate, the concentration of the compound silica sol should be adjusted, so as to form the experience that the concentration of the compound silica sol should be correspondingly and properly increased when the pore rate and the pinhole rate on the surface of the ceramic tile are large, and vice versa. It is considered that, within a certain range of concentration, the concentration of the compound silica sol increases, and accordingly the sol-gel reaction speed increases, and finally the thickness of the correspondingly formed compound antifouling silica-based film can be thickened a little. It is significant that the large pore and pinhole rate means large surface roughness, although in the operation process of the above-mentioned "coating and polishing multiple alternation" principle, the surface pores and pinholes are basically filled with the compound silica sol solution, but in the operation process, the water-based liquid content of the practical compound silica sol solution is more than or equal to 80 Wt%, so that the drying shrinkage of the silica sol solution which has penetrated into the pores is very large (the effective residual is only 20 Wt% at most), although the above-mentioned "coating and polishing multiple alternation" principle can be repeatedly filled, the pits are still difficult to be filled to a flat and firm place, in other words, after the film making process is finished, the corresponding dry glue film part on the pores still may leave traces of the pores to a certain extent-even if the size is not large, the pits also appear slightly, in fact, this can be seen when looking at the right angle in the direction of the light; obviously, the phenomenon can be compensated and improved by increasing the liquid concentration of the compound silica sol and promoting the thickness of the dry glue film to be increased. The reason why the compound silica sol solution is not improved once is that the reaction speed is high due to the large concentration, and the local concentration is obviously higher than the set average value due to any reason in the process, the corresponding sol-gel process product can form local thicker and rough defects, namely grinding marks, which are very unfavorable for the appearance decoration effect and the pollution prevention performance, and the grinding marks are a major factor for quality control in fact. Therefore, when the pore and pinhole rate of the ceramic tile is low, the concentration of the compound silica sol is correspondingly reduced in order to facilitate the process performance of overcoming grinding marks. In fact, the concentration of the compound silica sol liquid can be changed at different stages of time in the process of the operation cycle of the principle of 'coating and polishing are alternated for a plurality of times', for example, the concentration can be firstly higher and then reduced according to the time sequence, and even more complicated concentration combinations can be designed, so that the multivariable system optimization goals of 'filling pores, eliminating membrane traces and considering the membrane forming speed' can be realized.

Second, temperature factors are also noted: as with any chemical reaction, the temperature for this purpose relates to SiO₂The process of drying the adhesive film is always a factor of lifting the foot; furthermore, for gas phase condensed nanoscale silica commodity materials as chimney waste collection products of ferroalloy metallurgical plants [4]The 'differential thermal analysis curve' of the dry gel sample substance of the sol-gel reaction product of the nano-scale silicon dioxide and the SiO₂Micropowder and α -Al₂O₃The sample prepared from the fine powder and the alumina clinker particles is used for measuring the 'strength-heat treatment temperature' relation curve of the sample, and the conclusion which is significant for the occasion of the invention is obtained: (1) a distinct endothermic peak at 79 ℃ not far from room temperature on the differential thermal analysis curve, which is a dehydration reaction of silanol group according to the comprehensive research and explanation of the authors: ( ) The network-like structure thus formed determines a correspondingly significantly increased strength; (2) the intensity change rule shown by the relation curve (40-450 ℃) of the intensity and the heat treatment of the paper sample is that the intensity at 40-80 ℃ is obviously increased, the intensity is basically stable after 80 ℃, the intensity is kept at 10MPa, and the intensity is doubled compared with the corresponding value at 40 ℃; and then the temperature of 80-450 ℃ is a basically smooth horizontal line segment, namely the strength does not rise any more …. This points out a powerful feature of the present invention: due to the friction heating effect (certainly, the pressure rolling effect) in the grinding and polishing process of the grinding wheel, the obtained silicon dioxide-based compound surface antifouling film can pass through the structureThe dehydration reaction of the silanol groups is significantly more intense over room temperature environment, resulting indenser, higher strength. However, the invention uses the occasion of polishing the silicon dioxide anti-fouling coating on the surface of the ceramic tile, the decoration effect must be considered at the same time, and the experiment shows that the film forming process of the sol-gel reaction is very fast when the temperature is higher than 70 ℃, and the defect that the local film layer is thicker and rougher, which is not beautiful and also has the defect that the local film layer is not beautifulAnd no pollution is prevented. Thus, although there is a potential to raise the temperature to 80 ℃ and above, the temperature regulation must be compatible with various technical requirements, and if the wear scar cannot be effectively eliminated or avoided, the temperature should be avoided from being too high, and in general, the optimum temperature should be governed by the overall balance of requirements. Also, there is a renewed concern about stress factors: the grinding effect of the grinding head is directly influenced by the pressure, which has obvious promotion significance on the compactness of the surface film layer based on the compound silicon dioxide in formation, and a self-evident parallel function is that the pressure simultaneously promotes the phenomenon of friction and heat generation of the grinding head to be intensified, so that the comprehensive balance control requirement of the grinding head pressure is also led out. The pressure range adopted by the invention is as follows: the pressure data range of the grinding disc applied to the processed plate surface is (5-150) KPa, and the preferred value is (10-70) KPa. After the high-glossiness silicon dioxide-based compound antifouling film is prepared on the surface of the ceramic tile according to the principle of 'coating and polishing for multiple times alternately' described above, the whole tile surface is subjected to polishing treatment with a fluorosilicone organic compound solution having both hydrophobic and oleophobic properties or 'double-hydrophobic (oleophobic and hydrophobic) reinforced subsequent treatment'. In the subsequent treatment, the processed brick surface is almost always maintained at a higher temperature even close to the upper limit, so that the formed dry colloidal silicon dioxide-based compound antifouling film can remove more water to have a compact structure, and the fluorosilicone organic compound solution can penetrate into the nano-scale pore networks on the surface and inside of the dry glue as much as possible under the condition of the higher temperature, and when the solvent is volatilized, the fluorosilicone organic compound left on the pore interface can be firmly combined and remained in a chemical combination mode and is unique super-strong double-hydrophobic (hydrophobic and oleophobic) of the dry glueOil and hydrophobic) property, so that the surface and deep layer of the dry glue film can be oleophobic and hydrophobic, thereby reducing the interfacial adhesion force whether water (water) or oil (oil) pollution and having excellent anti-pollution capability.

With respect to all the above-mentioned operation techniques and control requirements, good results can be obtained by manual operation with a hand-held polishing machine, and the details will be further described in the following examples; this can be achieved in a continuous operation of mechanization, by following the polishing machine in the current stone industry or ceramic tile industry, the grinding heads are grouped according to the number of the required grinding heads, different grinding head groups are respectively provided with coating devices with the same or different operation periods, for example, some of the grinding heads are supplied with the compound silica sol glue solution, some of the grinding heads are clean water, some of the grinding heads are even stopped to coat so as to meet the 'blank grinding polishing (thermal polishing)' and the like, however, the process requirements of the compound silica sol liquid based on silica sol can be properly improved while the advantages of mechanization and automation adapting to batch production are outstanding, and the invention completely meets the requirements of manual and mechanization.

Detailed Description

Some specific process parameters are given in the following examples; these parameters are only used as illustrative examples and in no way imply that the invention is limited to these embodiments only.

Examples

For the following examples 1 to 3, as a coated substrate, a 600X 16(mm) light yellow polished tile sample, the surface of which had been polished and had a gloss of 65 gloss units, was visually inspected after the product package was unpacked and any adhered stains or stains observed to have been wiped off, as a coated substrate. The data relating to the formulation of the complex silica sol are shown in tables 83 and 94; the data for the fluorosilicone solutions prepared to enhance the hydrophobic and oleophobic properties of the surfaces are shown in Table 105. The preparation of the compound silica sol is carried out by using a small blade mixer and a beaker in a chemical laboratory, and the operation steps and the standing and aging period are consistent with those of the previous step.

The coating system of the compound silica sol is characterized in that the compound silica sol is locally brushed by a paint brush in a handheld two-time mode, and the brushing mode is dynamic: firstly, brushing a proper amount of 4 channels of compound silica sol at the upper left corner of the brick surface to be processed from the upper (front) edge to the lower (back) edge of the brick surface, wherein the first channel is close to the left edge of the brick surface, the length of each channel is approximately equal to the diameter of a wool felt grinding head, and the channels are approximately spaced by 100 mm; then, a hand-held portable hand-held grinding and polishing machine provided with a wool felt wheel (the surface of which is coated with the compound silica sol for a plurality of times in advance) is used, the grinding machine is started, the grinding head is lightly pressed on the brick surface, the grinding head is lightly moved to spread the slurry approximately uniformly, then, the grinding head is kept at a proper pressure by hand from the left edge, the whole brick surface is circularly and progressively ground in the directions of left and right-left-right-left … sequentially, the distance is staggered between every stroke of the grinding head, the diameter of the grinding head is kept to be approximately 1/4, the redundant glue solution is extruded and thrown away in the process, the remained glue solution enters a dynamic film forming state of a sol-gel reaction process, and the grinding, spreading and polishing effects of the grinding head are favorable for the compactness of a gel film in formation, The gel films formed in the adjacent processing periods are favorably and integrally combined with each other compactly and thickened; during the process, when the grinding wheel is close to an unwashed area without the glue solution, the corresponding unwashed blank area is rapidly coated with the glue solution with the length and the interval being the same as 2 or 3 times, and the grinding wheel is processed again and again according to the matching relation according to the principle of 'coating and polishing for multiple times and alternately' described above, namely according to the cyclic operation mode of '… A), B) and C) …'; in this process, the following 3 aspects should be noted: the first is to pay attention to the surface temperature of the brick and the pressure applied to the grinding head by a hand, if the temperature is high (the upper limit of the temperature is considered to be high enough when the hand is scalded and the hand is held for only 3 seconds-about 60-70 ℃), the pressure can be reduced, or the temperature is reduced by applying more glue solution and enhancing lubrication, so that the defect of grinding marks is avoided because the temperature is high easily; secondly, in the process of 'coating and polishing for multiple times of alternation', the brick surface can be stopped to be washed by water and observed in a small angle in a face-to-face manner after water is scraped off, whether the formed surface film is smooth and fine is uniform or not is carefully checked, and the local position which appears to be rough can be repaired by specially adding the glue solution and polishing the local position; when the temperature is lower, the brushing of the glue solution can be stopped and the whole brick surface is washed clean by water according to the requirement, but the grinding head operates as before or the pressure of the grinding head is increased simultaneously, so that the temperature can be increased and the grinding and polishing effects on the gel film layer in the forming process can be enhanced, and after the 'empty grinding and polishing' operation, the coating and polishing operations are carried out for a plurality of times alternately; thirdly, the material cause of the grinding crack is focused and eliminated, and the grinding crack defect is corrected by proper measures: (1) noting whether the brick surface is locally silted up and old and viscous slurry variant with greatly deteriorated fluidity, the analysis is that the side edge of the brick edge always tends to stick the viscous glue variant of the compound silica sol scraped from the grinding wheel, when the grinding head moves relative to the brick edge, the viscous glue variant is brought back to the brick surface by accident, which is an important cause of grinding marks, (2) the cleanliness of the grinding head, because the central hole of the wool felt head tends to silting upthe viscous old glue variant even close to semi-dry state, once the old glue variant falls off and is mixed on the surface being processed, the grinding marks are easily caused, in fact, the brick surface and the grinding head are both cleaned properly in the steps of water washing and air grinding, and (3) if the grinding marks are found to be formed, the grinding marks can be cleaned together with the adjacent areas, like the steps of water washing and air grinding " The grinding marks are often rougher and looser than the surrounding smooth film layer which is more fully rolled, so that the grinding marks can be removed by the water washing and air grinding operation and disappear, and the smooth film layer is remained in the original position; after the defects of grinding marks are corrected, the whole brick surface can be continuously subjected to the operations of coating and polishing for multiple times in an alternating way; finally, after the operation cycle of proper times is carried out, the operation and the cleaning wiping can be stopped, then the processed brick surface is checked, if the appearance is uniform and has no grinding mark, and the surface gloss of any part reaches 90 gloss units or even slightly higher, the compactness and the fineness of the film layer of the brick surface are judged to be qualified, and the brick surface with the unsatisfactory surface gloss can be repaired by reworking or only increasing the operation cycle of 'coating and polishing for multiple times' of certain times in most occasions, so that the qualified result can be achieved. The total processing time from the completion of the machining to the completion of the machining is 8-45 minutes, and an experienced operator can quite accurately grasp the 'machining duration', namely, when the machining cycle is almost close to the machining end point.

After the satisfactory silicon dioxide-based compound antifouling film is obtained, the steps of water washing and air grinding are inserted or not inserted into the whole brick surface, but the brick surface is ensured to be clean, and then the step is shifted to the last step, so that the brick surface is subjected to polishing treatment of fluorine-silicon organic compound solution with hydrophobic and oleophobic properties or is called as 'double-hydrophobic (oleophobic and hydrophobic) reinforced subsequent treatment'. At this time, the fluorosilicone compound solution is applied to the brick surface in a manner similar to the above-mentioned manner of "alternately coating and polishing a plurality of times" operation, except that the amount of the solution is much smaller, the continuous coating of each pass is changed into a few sparse spots, and the solution is not added frequently but only in order to leave a so-called "empty polishing" operation time; and another hand-held portable grinding and polishing machine special for carrying out the 'double-hydrophobic reinforced subsequent treatment' is used, the machine is provided with a special wool felt wheel (the surface of the special wool felt wheel is coated with the fluorosilicone organic compound solution for many times in advance), in the subsequent treatment, the processed brick surface is almost always kept at a higher temperature or even close to the upper limit, so that the formed dry colloidal silicon dioxide-based compound antifouling film can remove a plurality of water and become more compact, the fluorosilicone organic compound solution can penetrate into the nano-scale pore network on the surface and inside of the dry glue as much as possible under the higher temperature condition, when the solvent is volatilized, the fluorosilicone organic compound remained on the pore interface can be firmly combined and remained in a chemical or physical combination mode, and the dry glue film has excellent oleophobic and hydrophobic properties by the special super-strong double-hydrophobic (oleophobic and hydrophobic) properties Anti-contamination property of (1). The total time of the 'amphiphobic reinforcement subsequent treatment' is 1-5 minutes.

According to the processing method, the brick surface of the sample is detected according to a national standard GB/T3810.14-1999 detection method, and the antifouling performance reaches 4 grades and even reaches 5 grades of the highest grade.

TABLE 8 basic data of raw materials used in examples

	Silica sol	Silicone-acrylic emulsion	Styrene-acrylic emulsion	Polytetrafluoroethylene Emulsion and method of making
					Solid content (Wt％)	25	30	30	30
pH value	10.0	9.8	9.7	≥8.0
					Particle size	10～20 (nm)

TABLE 95 formulation and dosage of the Compound silica sols used in the examples

№		Silica sol	Water (W)	Silicon third Emulsion and method of making	Styrene-acrylic Emulsion and method of making	Polytetrafluoroethylene	Solid content (Wt％)	pH value
									1	With silica sol + water to 100%	50	50	6		0	13.3	10.2
With SiO2 ＝100	100		Silicon third Solid body 12		Polytetrafluoroethylene Solid body 0
								2			30	70		1.5	0.2	7.9	9.9
With SiO2 ＝100	100			Styrene-acrylic Solid body 5	Polytetrafluoroethylene Solid body 0.67
									3		20	80	0.09		0.09	5.0	9.1
With SiO2 ＝100	100		Silicon third Solid body 0.45		Polytetrafluoroethylene Solid body 0.45

TABLE 10 solutions of fluorosilicone organic compounds (trade names as supplied) used in the examples

Ingredients and their use in combination with the compound silica sols listed inTable 1

(solvent toluene includes commercial original and post-addition)

№	Fluorosilicone organic compounds Compound (I)	Crosslinking agent	Methyl silicone oil	Toluene (solvent)	The corresponding compound silicon listed in Table 1 Compounding condition of sol
						1	2	0.02	5	93	The samples were combined with samples No. 2 and No. 3 in Table 4
2	5	0.1	5	90	In combination with No. 1 in Table 4

Reference to the literature

[1]Composite Material national "Jiuwu" Key book twenty-first century New Material Cluster Chapter 5 Cement-based composite Material 5.3 Polymer Cement-based composite Material P210 Tianjin university Press 12 months 2000, 1 st edition

[2]Glass coating H.K. Purkle, Yongan, and other translation § 6.2.1.2.1, Per Critical, et al, immersion coating PP 98-117 scientific Press, 5/month, 1 st edition, 1988

[3]Xufeng edification of inorganic coating and coating technology, silica sol exterior wall coating P47 chemical industry press publication center for materiel science and engineering, 4 months, 1 st edition in 2002

[4]The low-temperature bonding mechanism of the micropowder and the SiO2 of section three of the New refractory material Li Xiao Ming's first chapter, FIGS. 1-13, and FIGS. 1-14 PP21-30, Metallurgical Press 1997, 6.1.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.

Claims (11)

1. A method for forming a silicon dioxide-based compound anti-fouling coating on the surface of a porcelain polished tile is characterized in that

a. Preparing a compoundsilica sol liquid based on silica sol;

b. coating the compound silica sol liquid on the surface of a ceramic polished tile to be processed, which is subjected to surface polishing in advance;

c. subjecting the compound silica sol liquid coated on the surface of the porcelain polished tile to polishing treatment from a moving grinding head;

the steps a, b and c can be circularly carried out once or more times until the thickness of the coating reaches 0.01-100 mu m; thereby forming a compound anti-fouling coating based on silicon dioxide on the surface of the porcelain polished tile.

2. The method according to claim 1, further comprising the steps of:

d. preparing a fluorosilicone organic compound solution, sol or emulsion with both oleophobic and hydrophobic characteristics;

e. c, coating the fluorine-silicon organic compound solution, sol or emulsion on the compound anti-fouling coating obtained in the step c;

f. subjecting said silica-based compound anti-fouling coating to a polish-dip treatment from a moving grinding head via a fluorosilicone organic compound solution, sol or emulsion that has been applied to the surface of the coating;

the above steps d-f may be performed cyclically one or more times.

3. A method according to claim 1 or 2The method, wherein the compound silica sol liquid comprises silica sol and coating colloid emulsion, and the solid phase content of the compound silica sol liquid is 0.1-20 wt%, preferably 1-15 wt%, more preferably 5-10 wt%; in the solid phase of the compound silica sol liquid, SiO is used₂The solid phase carried by the colloidal emulsion for coating is 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight.

4. The method according to claim 3, wherein the coating colloidal emulsion is selected from one or more of styrene-acrylic emulsion, ethylene-propylene emulsion, silicone-acrylic emulsion and fluorocarbon emulsion.

5. A process according to claim 3, wherein the SiO in the silica sol₂The content is 5 to 65 wt%, preferably 20 to 45 wt%, more preferably 30 to 40 wt%.

6. The method according to claim 4, wherein the compound components of the styrene-acrylic emulsion, the ethylene-propylene emulsion, the silicone-acrylic emulsion and the fluorocarbon emulsion are respectively:

① styrene-acrylic emulsion is quaternary copolymer emulsion of styrene, butyl acrylate, methyl methacrylate and methacrylic acid, or quaternary copolymer emulsion of butyl acrylate in which ethyl acrylate replaces the above combination, or ternary copolymer emulsion of styrene, ethyl acrylate and methacrylic acid;

② ethylene-propylene emulsion is copolymer emulsion of vinyl acetate and acrylic acid monomer;

③ Silicone acrylic emulsion, which is resin emulsion of acrylic ester monomer and organosilicon functional group graft copolymerization;

④ fluorocarbon emulsion comprises two kinds of fluorocarbon emulsion, wherein the fluorocarbon emulsion is perfluorocarbon polymer emulsion prepared by solution or emulsion polymerization of fluoromonomer, the fluorocarbon emulsion is fluorocarbon polymer emulsion prepared by solution or emulsion polymerization of one or more fluoromonomers and one or more non-fluorine-containing monomers, wherein the fluoromonomer comprises tetrafluoroethylene, vinyl fluoride, chlorotrifluoroethylene and hexafluoropropylene, and the non-fluorine-containing monomer comprises vinyl alkyl or allyl alkyl-containing ether monomer, ester monomer or aryl-containing ether monomer, ester monomer or unsaturated olefine acid.

7. The method according to claim 2, wherein the fluorosilicone organic compound is selected from one or more of the compounds having the general formula:

①(R1)₃Si(OSi(R_f)(R₂))_nOSi(R₁)₃

wherein n is an integer of 0 to 100; r₁Is a hydrocarbyl group; r₂Is alkyl, hydroxyl, amino; r_fIs CF₃(CF₂)_p(CH₂)_qWherein p and q are integers of 0-20;

②CF₃(CF₂)_m(CH₂)_nSi(OM)₃

wherein M and n are integers of 0-20, and M is a hydrocarbyl group; and

③CF₃(CF₂)_m(CH₂)_nSiCl_3-fR_f

wherein m and n are integers of 0-20, f is an integer of 0-3, and R is chlorine, bromine or alkyl.

8. The method according to claim 7, wherein the fluorosilicone organic compound is HO (Si (CH)₃)(CF₃(CH₂)₂)O)_nH、CF₃(CF₂)₇Si(OCH₃)₃、CF₃(CF₂)₇SiCl₃One or more of (a).

9. The method according to claim 1, wherein the thickness of the coating is 0.05-50 μm, preferably 0.1-10 μm.

10. A silica-based compound antifouling coating prepared according to the process of any one of claims 1 to 9.

11. A polished ceramic tile bearing the compound antifouling coating of claim 10.