CN109704347B - Silicon dioxide hollow sphere nano composite material and preparation and application thereof - Google Patents
Silicon dioxide hollow sphere nano composite material and preparation and application thereof Download PDFInfo
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Abstract
The invention relates to a silicon dioxide hollow sphere nano composite material, preparation and application thereof, and relates to the field of nano materials. The preparation method of the silicon dioxide hollow sphere nano composite material specifically comprises the following steps: respectively preparing the silica hollow sphere suspension and the nano silica acid sol; and mixing the silica hollow sphere suspension with the nano silica acid sol by stirring, and standing to obtain the silica hollow sphere nano composite material. The silica nano composite coating prepared by the silica nano composite material has good anti-reflection, self-cleaning and anti-fog effects, good mechanical wear resistance and weather resistance, good firmness with a substrate, no need of high-temperature calcination or other post-treatment modes in the preparation of the coating, capability of playing a role outdoors for a long time, and wide application range.
Description
Technical Field
The invention relates to the field of nano materials, in particular to a silicon dioxide hollow sphere nano composite material, and preparation and application thereof.
Background
With the development of science and technology, the development of multifunctional self-cleaning glass is very urgent. The multifunctional glass is glass with antireflection, self-cleaning (super-hydrophilic antifogging or super-hydrophobic) performance, ultrahigh mechanical strength and weather resistance. Meanwhile, the preparation method is also required to be simple and the preparation cost is also required to be low.
Self-cleaning glass (Self-cleaning glass) refers to glass which has unique physicochemical characteristics on the surface of common glass after being treated by a special physical or chemical method, so that the glass can achieve the cleaning effect without the traditional manual scrubbing method. Fogging of glass means that moisture or steam condenses on the surface of the glass article to form tiny water droplets. The Anti-fogging glass refers to that after ordinary glass is specially treated, the surface of the ordinary glass has super-hydrophilic characteristics, so that tiny water drops formed due to atomization are quickly paved, and the effects of mirror imaging, visibility and light transmittance of the glass are not influenced. Self-cleaning glass is mainly divided into two categories from the preparation method: super-hydrophilic self-cleaning glass; super hydrophobic self-cleaning glass. The common preparation method is to coat a layer of inorganic material on the surface of the glass product.
If the inorganic material coating is an ultra-hydrophilic substance, the contact angle of a small water drop on the surface of the glass approaches zero, when water contacts the surface of the glass, the small water drop quickly spreads on the surface of the glass to form an even water film, the ultra-hydrophilic property is shown, mirror imaging cannot be influenced, meanwhile, the water layer is thin, the influence on light transmittance is greatly reduced, the stains are taken away by the falling of the gravity of the even water film, and most of the stains can be removed by coating the ultra-hydrophilic inorganic material coating on the surface of the glass. Meanwhile, by utilizing the principle of super-hydrophilicity, the formation of water drops can be prevented, and the anti-fog effect is achieved.
The research on self-cleaning and anti-fogging of glass has been started in 60 years in the 20 th century, and in the aspect of basic research, currently, well-known companies in developed countries in the world are dedicated to the research, development and manufacture of self-cleaning glass, such as Pilkington company, TOTO company in Japan, PPG company in the United states, GEA company in Germany, VTA company, UIC company and the like; in the aspect of application development, Japan is first developed, popularized and applied with TiO2The glass manufacturers such as photocatalytic self-cleaning glass, Pilkington company in the UK, PPG company in the United states and the like also consider the large market of development, processing, production and popularization and application of the product. Application of TiO in development by Pilkington glass company in UK2The aspect of photocatalytic self-cleaning glass is at the forefront of European and American glass manufacturers, and the product is popularized to the glass markets of Europe and other countries (such as the United states) before the year 2002, is sold in public batches and is subsequently promoted in North America, Australia in the great county, Japan in Asia and other regions and countries (Chenabin, architectural glass and industrial glass 2004, No.6, 12-15); transparent composite self-cleaning antifogging glass developed by U.S. W.L. Tonar et al (W.L. Tonareta1. electrophoretic device HavingASelf-cleaning Hydrophilical coating. United states patent application publication US2001/00210066A1,2001-09-13; K.Toru.Vehicl. Vehicl. United states patent application US5594585: 1997-01-14; K.Toru.Anti-fogElement. US5854708: 1998-12-29; K.Takayamaetaa 1.method for hydrologic Informication coating Cooperation coating film and photocatalytic coating composition. United states patent application publication No. 2001/008696A1,2001-13) is a transparent glass substrate having a photocatalyst surface formed thereon and a transparent oxide photocatalyst coating (SiO.2001-SiO 2, SiO 2 is a transparent inorganic photocatalyst coating (SiO 2-13) having a photocatalyst effect formed thereon, and a transparent surface photocatalyst coating (SiO 2, a transparent inorganic photocatalyst coating is a transparent glass substrate having a photocatalyst formed thereon)2And Al2O3) And (4) coating. However, these techniques all utilize TiO2The photocatalytic property promotes the surface to be super-hydrophilic, and the applicable condition is limited because the catalysis can be carried out only in the environment with illumination; in addition, although the surface of such a pore structure can improve hydrophilicity, the pore opening is easily blocked by a substance which is difficult to volatilize or nano dust, and durability is not preferable.
Although the domestic research starts late, the remarkable progress is also achieved, hundreds of related patents and technical achievements exist, and glass antifogging agent products are continuously pushed out. In order to avoid the formation of fine water droplets on the glass article, which leads to fogging and a decrease in transparency, the following measures are generally taken: (1) spraying a layer of surfactant on the surface of the glass to remove water drops and dust deposited on the surface of the glass; (2) coating an organic water-absorbing nano coating on the surface of the glass; (3) installing a heating device, and evaporating water drops on the surface of the glass by heating; (4) an ultrasonic dispersion and heating device is arranged to simultaneously disperse and heat water drops on the surface of the glass, so that the purpose of rapid evaporation is achieved. However, these methods have their own limitations: the method (1) is inconvenient because the surfactant needs to be sprayed and brushed repeatedly at regular intervals; the method (2) is poor in abrasion resistance and heat resistance of the glass article due to the use of the organic substance; in the method (3), the water drops are heated and evaporated for 7-10 minutes usually, so that the timeliness is poor, additional energy is required, and the energy consumption is large, so that the method is not practical; the device of the method (4) is complex, has more elements and high cost (Liu Paoyong smart, Liyuping national building material science and technology journal- "glass" No. 3 and No. 16-19 in 2002). The technology of normal temperature curing nano self-cleaning glass of China science nano technology engineering center limited company (China science nano company for short) is remarkably developed, the manufacturing of the large-plate-surface self-cleaning glass is completed by combining a glass deep processing technology, and the method is applied to construction projects such as national large theaters, automobile exhibition halls and the like. The contact angle of water on the surface of the self-cleaning glass prepared by the Chinese Korea company is 6.5 degrees, the contact angle of water on the surface of the self-cleaning glass prepared by a certain famous foreign company is 17 degrees, and therefore, the hydrophilicity of the self-cleaning glass prepared by the Chinese Korea company is far better than that of the self-cleaning glass prepared by the certain famous foreign company (Chenabin, building glass and industrial work glass)Technical glass 2004, No6, 12-15). Unfortunately, this technique utilizes TiO2The photocatalytic property of (a) to improve the hydrophilicity of the substrate surface, must exhibit good hydrophilicity in an environment irradiated with ultraviolet light, and is difficult to achieve in a dark environment, thus limiting the range of applications. In general, the self-cleaning and anti-fogging effects and durability of these current technologies are not yet ideal.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
The invention aims to provide a silicon dioxide hollow sphere nano composite material, and preparation and application thereof.
According to a first aspect of the invention, a preparation method of a silica hollow sphere nanocomposite is provided, wherein the silica hollow sphere nanocomposite is formed by compounding a silica hollow sphere suspension and a nano silica acid sol, and the method specifically comprises the following steps:
respectively preparing the silica hollow sphere suspension and the nano silica acid sol;
uniformly mixing the silica hollow sphere suspension and the nano silica acid sol by stirring, then standing,
wherein, the temperature of the standing is controlled to be 4-30 ℃, and the temperature is more preferably 20-25 ℃;
wherein the standing time is controlled to be more than or equal to 48 hours.
Further, the particle size of the silica hollow sphere in the silica hollow sphere suspension is 20-120nm, and the thickness of a shell layer is 5-15 nm;
the nano-silica acid sol has chain-shaped nano-silica, the condensation degree of the nano-silica acid sol is about 70-90%, and the average length of the chain-shaped nano-silica is about 5 nm.
Further, the silica hollow sphere suspension is formed by dispersing the silica hollow spheres in a solvent,
wherein the solvent is at least one selected from ethanol, methanol, isopropanol, propylene glycol and n-butanol.
Further, the preparation process of the nano silica acid sol is as follows:
the alkoxysilane is subjected to condensation polymerization under an acidic catalysis condition to form non-particle chain-like nano-silica species, so that the nano-silica acidic sol is formed.
According to a second aspect of the invention, there is provided a silica hollow sphere nanocomposite prepared by a method according to any one of the preceding aspects.
According to a third aspect of the present invention, there is provided a method for preparing a silica hollow sphere nano-coating layer, the method for preparing a nano-coating layer on a surface of a substrate by performing at least one pulling operation on the substrate using the silica nanocomposite according to the above aspect,
wherein the thickness of the silica hollow sphere nano coating is 50-200 nm;
wherein the light transmittance of the silicon dioxide hollow sphere nano coating is more than or equal to 95 percent, preferably more than or equal to 97.8 percent;
wherein the contact angle of the silica hollow sphere nano coating is less than or equal to 8 degrees, preferably 3.8 degrees;
wherein the hardness of the silicon dioxide hollow sphere nano coating is more than or equal to 3H.
Further, the substrate is glass, and the glass is acrylic glass, solar glass, window glass, mirror glass or automobile glass.
Further, the at least one pulling operation specifically includes the steps of:
immersing the substrate in the silicon dioxide hollow sphere nano composite material, then pulling, standing,
wherein, the pulling speed of the substrate is controlled to be 20-200mm/min during immersion; controlling the immersion time to be 5-50 s; standing for 5-60 seconds indoors after each pulling-out.
According to a fourth aspect of the invention, a silica hollow sphere nano-coating is provided, which is prepared by the preparation method according to any one of the above aspects.
According to a fifth aspect of the present invention, there is provided a coated glass, the glass substrate is covered with the silica hollow sphere nano-coating according to the above aspect,
wherein, the glass substrate is acrylic glass, solar glass, window glass, mirror glass or automobile glass.
Compared with the prior art, the invention has the beneficial effects that at least:
1. according to the invention, the silica hollow sphere nano composite material is formed by compounding the silica hollow sphere suspension and the nano silica acidic sol, the residual alkoxy in the nano silica acidic sol can be self-crosslinked and can be used for crosslinking the silica hollow spheres in the silica hollow sphere suspension in the compounding process so as to form a three-dimensional network structure, and various performances of the silica hollow sphere nano coating can be obviously improved without a crosslinking agent.
2. The preparation method has the advantages of simple operation, low cost and good repeatability, and can be used for large-scale industrial production; meanwhile, the prepared silicon dioxide hollow sphere nano composite material is good in stability, can be stored at room temperature for a long time, can be prepared into a membrane in various conventional modes, is good in membrane preparation process operability, and is convenient for actual operation and application.
3. The silica hollow sphere nano-coating has good anti-reflection, self-cleaning and anti-fog effects, the light transmittance is more than or equal to 97%, and the contact angle is less than or equal to 8 ℃; meanwhile, the coating also has good mechanical wear resistance, weather resistance and firmness, the hardness of the coating is more than or equal to 3H, the use is not limited, the coating can play a role outdoors for a long time, and the application range is wide.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 shows a flow chart of a method for preparing a silica hollow sphere nanocomposite according to the invention;
fig. 2 shows a scanning electron micrograph (a) and a transmission electron micrograph (b) of a silica nano hollow sphere according to an embodiment of the present invention;
FIG. 3 shows a transmission diagram of a silica hollow sphere nanocomposite according to another embodiment of the present invention;
FIGS. 4a to 4f are graphs showing light transmittance of nanocoated-covered glass sheets prepared under different reaction conditions according to different embodiments of the present invention;
FIGS. 5a to 5f show scanning electron micrographs of nanolayered coatings constructed under different reaction conditions according to different embodiments of the present invention;
FIG. 6 is a graph showing the effect of the reaction under different reaction conditions according to different embodiments of the present invention;
FIG. 7 shows a comparison of antifogging effects of a nanocoated glass sheet surface under different reaction conditions according to an embodiment of the present invention;
FIG. 8 shows pencil hardness test results of nanocoatings under different reaction conditions according to one embodiment of the present invention.
Detailed Description
The technical solution of the present invention is further described with reference to the following specific embodiments.
The silicon dioxide hollow sphere nano composite material is mainly formed by compounding a silicon dioxide hollow sphere suspension and a nano silicon dioxide acid sol; wherein: the particle size of the silica hollow sphere in the silica hollow sphere suspension is 20-120nm, and the thickness of a shell layer is 5-15 nm; the nano-silica acid sol has chain-shaped nano-silica, the condensation degree of the nano-silica acid sol is 70-90%, and the average length of the chain-shaped nano-silica is about 5 nm.
In the invention, the silica hollow sphere suspension refers to a mixed liquid mainly formed by the silica hollow spheres and a solvent; more specifically, hollow silica spheres are dispersed in a solvent to form a suspension. The solvent in the silica hollow sphere suspension is not particularly limited, and may be, for example, at least one selected from the group consisting of ethanol, methanol, isopropanol, propylene glycol and n-butanol, and preferably ethanol. In addition, the formation mode of the silica hollow sphere suspension is not strictly limited, and the silica hollow sphere may be directly dispersed in a solvent to form the suspension, or the suspension may be prepared by reacting raw materials containing a solvent, an alkali solution and an alkoxysilane.
In the invention, the nano-silica acidic sol refers to a nano-silica sol prepared under an acidic catalysis condition; more specifically, alkoxysilane is subjected to condensation polymerization (abbreviated as condensation polymerization) under an acidic catalysis condition to form non-particle chain-like nano silica species, thereby constituting the nano silica acidic sol. Wherein, the condensation degree refers to the reaction degree of condensation monomers (namely alkoxy silane) in the nano silicon dioxide acid sol; the condensation degree of the nano-silica acid sol is 70-90%, namely 70-90% of alkoxy in the alkoxy silane is subjected to condensation polymerization, so that the nano-silica acid sol has 10-30% of residual alkoxy.
The composite form of the silica hollow sphere suspension and the nano silica acid sol can form the composite through mixing, standing and the like; in particular, the standing time is more than or equal to 48 hours, as shown in FIG. 1. In the compounding process, residual alkoxy in the nano-silica acidic sol can crosslink the silica hollow spheres in the silica hollow sphere suspension to form a three-dimensional network structure; more specifically, residual alkoxy in the nano-silica acidic sol can form a Si-O-Si bond through self-crosslinking, and can form a Si-O-Si bond through crosslinking with Si-OH of the silica hollow sphere, so that the performances of the silica hollow sphere nanocomposite such as wear resistance, weather resistance and firmness can be remarkably improved.
According to the silica hollow sphere nanocomposite material, the specific silica hollow sphere suspension and the nano silica acid sol are compounded to form a three-dimensional network structure, so that the silica hollow sphere nano coating with excellent performances such as anti-reflection, self-cleaning, anti-fog, mechanical wear resistance, weather resistance and firmness can be prepared; the reason for this may be: the silica hollow spheres have small size, and can form enough pores by stacking, and meanwhile, the surface of the coating has enough surface roughness, so that the refractive index of the coating is reduced, and the coating has good anti-reflection, hydrophilic anti-fog and self-cleaning performances.
Researches find that the high or low condensation degree of the nano-silica acidic sol is not beneficial to the crosslinking of the silica hollow spheres and the improvement of the performance of the composite material; specifically, when the condensation degree of the nano-silica acidic sol is too high, the silica hollow spheres cannot form sufficient cross-linking, so that the strength, wear resistance, firmness and the like of the coating are reduced, and when the condensation degree of the nano-silica acidic sol is too low, residual alkoxy exists in the silica nanocomposite, so that the contact angle of the surface of the coating is increased, and the improvement of the anti-reflection performance, hydrophilic anti-fog performance, self-cleaning performance and the like of the coating is not facilitated, so that the appropriate condensation degree is 70-90%, preferably 75-85%, and more preferably 80-85%. In addition, in the present invention, the degree of condensation of the nanosilica acid sol can be adjusted by the amount of the acid, and the greater the amount of the acid, the higher the degree of condensation.
The invention does not strictly limit the silicon dioxide hollow sphere, and the silicon dioxide hollow sphere is preferably a non-porous silicon dioxide hollow sphere; the nonporous silica hollow sphere means that the silica hollow sphere shell layer has substantially no pores. Researches find that the porous silica hollow sphere contains large-size cavities, so that effective porosity is provided, the refractive index of the coating can be reduced, and the anti-reflection performance is achieved.
In the invention, the silica hollow sphere suspension and the nano silica acid sol can be prepared by adopting the conventional method in the field as long as the suspension and the acid sol with the relevant quality requirements of the invention are prepared; namely, the preparation method of the silica hollow sphere suspension at least needs to ensure that the particle size of the silica hollow sphere in the suspension is 20-120nm and the shell layer thickness is 5-15nm, and the preparation method of the nano-silica acid sol at least needs to ensure that the condensation degree of the nano-silica acid sol is 70-90 percent and the average length of the chain nano-silica is about 5 nm.
More specifically, the preparation method of the silica hollow nanosphere suspension can comprise the following steps: raw materials containing a solvent, alkali liquor, polyacrylic acid and alkoxy silane are reacted. The conditions of the above reaction are not strictly limited as long as the preparation of the silica hollow sphere suspension having the above quality requirements of the present invention is facilitated. The molecular weight of polyacrylic acid is controlled to be 2000-1000; specifically, the volume ratio of the solvent, the alkali liquor, the polyacrylic acid and the alkoxy silane can be controlled to be 90: 3-6: 0.4-0.8: 1-3, and the preparation range is favorable for preparing the specific silicon dioxide hollow sphere.
And washing the hollow sphere by repeated water to remove polyacrylic acid, ammonia water and the like in the hollow sphere suspension. And dispersing the washed hollow spheres in ethanol to prepare the hollow sphere composite nano material.
Researches show that the preparation method has good stability and repeatability, has no strict requirement on the scale of a reaction system, and can have good repeatability even if the preparation is carried out under large-scale conditions, so the preparation method is particularly suitable for large-scale industrial production. The specific reaction volume can be reasonably determined according to actual requirements, and can be 0.4-20L, for example.
In the present invention, the preparation method of the nano silica acid sol may include: reacting raw materials containing a solvent, an acid solution and alkoxysilane; wherein the volume ratio of water to ethanol to acid liquor to alkoxy silane can be controlled to be 5-20: 200-300: 0.05-0.2: 10-40. The proportion range is beneficial to preparing the chain-shaped nano silicon dioxide with the specific size.
Researches show that the preparation method of the nano-silica acidic sol has good stability and repeatability, has no strict requirement on the scale of a reaction system, and can have good repeatability even if the preparation is carried out under large-scale conditions, so the preparation method is particularly suitable for large-scale industrial production. The specific reaction volume can be reasonably determined according to actual requirements, and can be 0.2-5L, for example.
In the invention, standing is used for realizing the composition of the silica hollow sphere suspension and the nano silica acid sol; namely, the self-crosslinking of the residual alkoxy in the nano-silica acidic sol and the crosslinking effect on the silica hollow spheres in the silica hollow sphere suspension are realized. The standing condition is not strictly limited; for example, the temperature at the time of standing may be controlled to 4 to 30 ℃, preferably 20 to 25 ℃, and the standing time may be controlled to 48 hours or more. Researches find that when the standing temperature is 20-25 ℃, the contact angle of the coating can be further reduced, and the contact angle can be reduced to 4-6 ℃; in addition, the stable crosslinking of the whole system can be basically realized when the standing time is more than 48h, the product can be stored for a long time, and the quality is stable.
In the invention, the mass percentage of hollow spheres in the prepared silica hollow sphere suspension is 0.5-5%, and the volume ratio range of the hollow sphere suspension to the acidic sol solution is as follows: 8: 50-24: 50.
the invention provides a preparation method of a silicon dioxide hollow sphere nano coating, which is used for preparing the nano coating by adopting the silicon dioxide hollow sphere composite material or the silicon dioxide hollow sphere nano composite material prepared by the preparation method. The method adopted by the invention is not strictly limited, and the conventional film-making method in the field, such as a pulling method, a spraying method and the like, can be adopted; in addition, the substrate used for the film formation is not strictly limited, and the substrate may be glass, such as acrylic glass, solar glass, window glass, mirror glass, automotive glass, and the like.
The preparation method of the silicon dioxide nano composite film can comprise at least one pulling step or at least one spraying step; wherein the pulling step may include: a substrate is immersed in the silica nanocomposite, subsequently pulled up, and then left to stand. In the step of lifting, the descending speed of the substrate can be controlled to be 20-200mm/min during immersion; controlling the immersion time to be 5-50 s; controlling the rising speed of the substrate to be 20-200mm/min during pulling; controlling the standing time to be 60-120 s; standing for 5-60 seconds indoors after each pulling-out.
The invention provides a silicon dioxide hollow sphere nano-coating which is prepared according to the preparation method. Wherein the thickness of the silicon dioxide hollow sphere is 50-200 nm; the light transmittance is more than or equal to 95 percent, preferably more than or equal to 97.8 percent; the contact angle is less than or equal to 8 degrees, and the preferred angle is 3.8 degrees; the hardness is more than or equal to 3H.
The invention also provides coated glass, wherein the silicon dioxide hollow sphere nano coating is coated on the surface of a substrate; the substrate is not strictly limited and may be acryl glass, solar glass, window glass, mirror glass, automobile glass, etc. The specific application field of the coated glass is not strictly limited, and the coated glass can be widely applied to the related fields of daily life, industry, astronomy, military science, electronics and the like, and particularly can be applied to solar cells and the like which work outdoors for a long time.
The invention also provides a preparation process of the hydrophilic anti-fog self-cleaning silica nano-coating with high mechanical strength and anti-reflection performance, which is characterized by comprising the following steps: the process comprises the steps of mixing an acidic sol solution and a silica hollow nanosphere suspension, and depositing the mixture on a substrate by adopting a pulling and spraying method, so that the coating contains enough porosity and the surface of the coating has enough surface roughness, thereby achieving the anti-reflection and anti-reflection properties and the hydrophilic anti-fog properties; the purpose of adding the acidic sol solution is to crosslink the silicon dioxide hollow nanospheres and fill part of gaps among the silicon dioxide hollow nanospheres so as to increase the mechanical wear resistance of the coating. The organic combination of the acidic sol solution and the suspension of the hollow nanospheres is promoted by regulating and controlling the proportion of the acidic sol solution to the suspension of the hollow nanospheres, so that the constructed nano coating has hydrophilic antifogging self-cleaning performance with high mechanical strength and anti-reflection performance.
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The raw materials and equipment used in the examples were as follows:
ethanol: the density is about 0.789 g/mL; concentrated ammonia water: the concentration is 25-28%, and the density is about 0.913 g/mL; concentrated hydrochloric acid: the concentration is about 37%; tetraethoxysilane: the molecular weight is 208.33g/mol, and the density is about 0.93 g/mL; lifting a coating instrument: purchased from Shanghai Sanyu technology, Inc.
Example 1
Preparing the silicon dioxide hollow nanospheres with the particle size of 20-120 nm:
(1) adding 0.4-0.8 ml of polyacrylic acid solution with the molecular weight of 5000 (wherein the mass percentage of the polyacrylic acid is 50%) into 3-6 ml of ammonia water, and stirring in a water bath at 25 ℃;
(2) adding 90 ml of ethanol into a 500 ml flask, adding the mixed solution in the step (1) into the flask, and stirring in a water bath at 25 ℃;
(3) and (3) adding 1-3 ml of tetraethoxysilane into the mixed solution in the step (2) at 25 ℃, and continuously stirring for 10-20 hours to obtain the silicon dioxide hollow nanospheres.
(4) And (3) obtaining the sediment of the silicon dioxide hollow nanospheres by a centrifugal method, adding 500 ml of water, carrying out ultrasonic treatment for 30 minutes, then carrying out centrifugal separation to remove polyacrylic acid, and repeating the water washing process twice. Finally, the obtained hollow spheres were dispersed in 90 ml of ethanol to prepare a hollow sphere ethanol suspension.
FIG. 2 is a perspective view of the hollow silica nanospheres prepared above; as can be seen from FIG. 2, the particle size of the silica hollow nanospheres in the suspension prepared in this example is 20-120nm, and the shell thickness is 5-15 nm.
Example 2
Preparing nano-silica acid sol:
adding 0.05-0.2 mL of concentrated hydrochloric acid (37%) into 5-20 mL of water at room temperature (25 ℃) to prepare a dilute hydrochloric acid solution; and then, adding the dilute hydrochloric acid solution into 200-300 mL of ethanol, and uniformly stirring.
And adding 10-40 mL of tetraethoxysilane into the mixed solution, stirring at room temperature for reaction for 4 hours, standing at room temperature for reaction for 4 days to obtain the nano-silica acid sol, and storing at 4 ℃.
The detection is carried out by adopting solid nuclear magnetic resonance, and the result shows that: the condensation degree of the prepared nano-silica acid sol is about 70-90%, and the average length of the chain-shaped nano-silica is about 5 nm.
Example 3
Preparing a mixed solution of the silica hollow sphere and the acidic sol solution:
using the ethanol suspension of hollow spheres prepared in example 1, ethanol suspensions having hollow sphere mass concentrations of 0.5%, 1%, and 5% were prepared by adding ethanol.
50 ml of ethanol suspension of low-concentration (0.5%) or high-concentration (1%) silica hollow spheres was added to the acidic sol solution prepared in example 2 at different volumes under stirring to prepare a mixed solution. The volumes of the added acid sol liquid are regulated to be 8, 10, 12, 14, 16, 18, 20, 22 and 24 milliliters respectively, so that mixed liquid with different volume ratios of the hollow sphere suspension liquid and the acid sol liquid is prepared. And then standing for more than 48 hours at room temperature (25 ℃) to prepare the silicon dioxide hollow sphere nano composite material.
FIG. 3 is a transmission diagram of the silica hollow sphere nanocomposite prepared by using a mixed solution of 8 ml of an acidic sol solution and a low concentration (0.5%) silica hollow sphere ethanol suspension; as can be seen from the figure, the acidic sol solution in the silica hollow sphere nanocomposite material enables the silica hollow sphere to be mutually crosslinked to form a three-dimensional network structure, chain species in the acidic sol solution are also mutually crosslinked to form the three-dimensional network structure, and a plurality of gaps with the size of 3-100 nm are formed inside the three-dimensional network structure.
Example 4
The nano coating is prepared by a pulling method, and the preparation method comprises the following steps:
(1) and ultrasonically cleaning the glass sheet in ethanol for 5-30 minutes.
(2) The cleaned glass sheet in the step (1) is respectively pulled for 1,2, 3, 4 and 5 times in the mixed solution of 8 ml of acid sol solution and 50 ml of low-concentration (0.5%) hollow sphere ethanol solution in the embodiment 3, the pulling speed is 20-200mm/min, the glass sheet is soaked in the suspension for 5-50 seconds, and the glass sheet stands in a room for 5-60 seconds after being pulled out every time.
Fig. 4(a) shows a graph of transmittance of the glass sheet on which 1,2, 3, 4, 5 times "a mixed solution of 8 ml of an acid sol solution +50 ml of a low concentration hollow sphere ethanol solution" was deposited in example 4, from which: the glass covered with the coating has obvious anti-reflection phenomenon in the wavelength range of visible light and near infrared light, the glass with the nano coating formed by pulling for 4 times has the highest light transmittance, the average light transmittance is increased by more than 5%, and the glass has the highest light transmittance at the wavelength of 555nm, which reaches 97%.
FIG. 5(a) scanning electron micrograph of a nanocoating prepared by 4 times of pulling "a mixed solution of 8 ml of an acidic sol solution and 50 ml of a low-concentration ethanol solution of hollow spheres" deposited on a glass sheet according to example 4 of the present invention, it can be seen that the coating is formed by stacking hollow spheres, the surface of the coating is flat, and there are many voids between the inside of the hollow spheres and the hollow spheres, which cause a decrease in refractive index, so that the glass coated with the coating has high light transmittance, and the voids are also advantageous for penetration and spreading of water droplets.
Example 5
Refer to example 4 method for preparing nano coating.
(1) And ultrasonically cleaning the glass sheet in ethanol for 5-30 minutes.
(2) In example 3, the glass sheet cleaned in step (1) was mixed with a mixture of 10 ml of an acidic sol solution and 50 ml of a low-concentration (0.5%) hollow sphere ethanol solution, a mixture of 12 ml of an acidic sol solution and 50 ml of a low-concentration (0.5%) hollow sphere ethanol solution, a mixture of 14 ml of an acidic sol solution and 50 ml of a low-concentration (0.5%) hollow sphere ethanol solution, a mixture of 16 ml of an acidic sol solution and 50 ml of a low-concentration (0.5%) hollow sphere ethanol solution, a mixture of 18 ml of an acidic sol solution and 50 ml of a low-concentration (0.5%) hollow sphere ethanol solution, a mixture of 20ml of an acidic sol solution and 50 ml of a low-concentration (0.5%) hollow sphere ethanol solution, a mixture of 22 ml of an acidic sol solution and 50 ml of a low-concentration (0.5%) hollow sphere ethanol solution, and a mixture of 24 ml of an acidic sol solution and 50 ml of a low-concentration (0.5%) hollow sphere, "a mixed solution of 8 ml of an acidic sol solution and a hollow sphere ethanol solution having a concentration of 50 mm higher (1%)," a mixed solution of 10 ml of an acidic sol solution and a hollow sphere ethanol solution having a concentration of 50 mm higher (1%), "a mixed solution of 12 ml of an acidic sol solution and a hollow sphere ethanol solution having a concentration of 50 mm higher (1%)," a mixed solution of 14 ml of an acidic sol solution and a hollow sphere ethanol solution having a concentration of 50 mm higher (1%), "a mixed solution of 16 ml of an acidic sol solution and a hollow sphere ethanol solution having a concentration of 50 mm higher (1%)," a mixed solution of 18 ml of an acidic sol solution and a hollow sphere ethanol solution having a concentration of 50 mm higher (1%), "a mixed solution of 20ml of an acidic sol solution and a hollow sphere ethanol solution having a concentration of 50 mm higher (1%)," a mixed, Respectively pulling the mixture of 24 ml of acid sol solution and 50 ml of hollow sphere ethanol solution with the rising concentration (1%) for 1,2, 3, 4 and 5 times, wherein the pulling speed is 20-200mm/min, soaking the mixture in the suspension for 5-50 seconds, and standing the mixture indoors for 5-60 seconds after pulling out each time.
Fig. 4(b) shows a graph of transmittance of the glass sheet on which 1,2, 3, 4, 5 times "a mixed solution of 10 ml of an acid sol solution +50 ml of a low concentration (0.5%) hollow sphere ethanol solution" was deposited in example 5, from which: the glass covered with the coating has obvious anti-reflection phenomenon in the wavelength range of visible light and near infrared light, the glass with the nano coating formed by pulling for 4 times has the highest light transmittance, the average light transmittance is increased by more than 5%, and the glass has the highest light transmittance at the wavelength of 550nm and reaches 97%.
Fig. 4(c) shows a graph of transmittance of the glass sheet on which 1,2, 3, 4, 5 times "a mixed solution of 12 ml of an acid sol solution +50 ml of a low concentration (0.5%) hollow sphere ethanol solution" was deposited in example 5, from which: the glass covered with the coating has obvious anti-reflection phenomenon in the wavelength range of visible light and near infrared light, the glass with the nano coating formed by pulling for 3 times has the highest light transmittance, the average light transmittance is increased by more than 5%, and the glass has the highest light transmittance at the wavelength of 520nm and reaches 97%.
Fig. 4(d) shows a graph of transmittance of the glass sheet on which 1,2, 3, 4, 5 times "a mixed solution of 8 ml of an acidic sol solution +50 ml of a hollow sphere ethanol solution at a raised concentration (1%)" was deposited in example 5, from which it can be found that: the glass covered with the coating has obvious anti-reflection phenomenon in the wavelength range of visible light and near infrared light, the glass with the nano coating formed by pulling for 2 times has the highest light transmittance, the average light transmittance is increased by more than 5.8 percent, and the glass has the highest light transmittance at the wavelength of 520nm and reaches 97.8 percent.
Fig. 4(e) shows a graph of transmittance of the glass sheet on which 1,2, 3, 4, 5 times "a mixture of 10 ml of an acidic sol solution +50 ml of a hollow sphere ethanol solution at a raised concentration (1%)" was deposited in example 5, from which it can be found that: the glass covered with the coating has obvious anti-reflection phenomenon in the wavelength range of visible light and near infrared light, the glass with the nano coating formed by pulling for 2 times has the highest light transmittance, the average light transmittance is increased by more than 5.8 percent, and the glass has the highest light transmittance at the wavelength of 540nm and reaches 97.8 percent.
Fig. 4(f) shows a graph of transmittance of the glass sheet on which 1,2, 3, 4, 5 times "a mixture of 12 ml of an acidic sol solution +50 ml of a hollow sphere ethanol solution at an elevated concentration (1%)" was deposited in example 5, from which it can be found that: the glass covered with the coating has obvious anti-reflection phenomenon in the wavelength range of visible light and near infrared light, the glass with the nano coating formed by pulling for 2 times has the highest light transmittance, the average light transmittance is increased by more than 5.4 percent, and the glass has the highest light transmittance at the wavelength of 540nm and reaches 97.4 percent.
Fig. 5(b) and 5(c) are scanning electron micrographs of the nanocoatings prepared by depositing a mixture of 4 times of pulling "10 ml of the acid sol solution +50 ml of the low-concentration (0.5%) hollow sphere ethanol solution" and 3 times of pulling "12 ml of the acid sol solution +50 ml of the low-concentration (0.5%) hollow sphere ethanol solution on the glass sheet according to example 5 of the present invention, and it can be seen from the scanning electron micrographs that the coating is formed by stacking hollow spheres, the surface of the coating is flat, and many voids are present between the hollow sphere cavity and the hollow sphere, which cause a decrease in refractive index, so that the glass coated with the coating has a higher light transmittance, and in addition, as the amount of the acid sol solution is increased, the content of the flocculent component in the coating is correspondingly increased.
FIG. 5(d), FIG. 5(e) and FIG. 5(f) are the mixed solution of 2 times pulling of "8 ml of acidic sol solution +50 mm high concentration (1%) hollow sphere ethanol solution", 2 times pulling of "10 ml of acidic sol solution +50 mm high concentration (1%) hollow sphere ethanol solution" and 2 times pulling of "12 ml of acidic sol solution +50 mm high concentration (1%) hollow sphere ethanol solution" deposited on the glass sheet in example 5 of the present invention, according to a scanning electron microscope image of the prepared nano coating, the proportion of the hollow spheres in the coating is obviously increased due to the high-concentration hollow spheres, the hollow spheres are closely stacked on the surface of the coating, the hollow spheres are crosslinked together by the acidic sol solution, and the content of the flocculent component in the coating is correspondingly increased along with the increase of the adding amount of the acidic sol solution.
FIG. 6 is a graph showing the relationship between the contact angle and the volume of the acidic sol solution when the surface of a glass sheet covered with a nano-coating prepared by depositing 3. mu.l of water droplets on the glass sheets in examples 4 and 5 and pulling the "mixture" 2 or 3 times, respectively, is spread for 0.5 seconds. As shown, the contact angle of the water drop is less than 8 degrees. Digital photographs of the contact angle when the surface of a glass sheet on which a nano-coating layer having 2 times of pulling a mixed solution of 12 ml of an acidic sol solution and 50 ml of a high-concentration hollow sphere was deposited was spread for 0.5 seconds showed that the contact angle was 3.8 degrees, and super-hydrophilicity was achieved.
Fig. 7 shows a comparison of antifogging effect of blank glass and glass sheet surface deposited with nanocoating pulled 2 times "mixed solution of 12 ml acid sol solution and 50 ml high concentration hollow spheres" in example 5. The coated portion may be effective to inhibit the formation of mist.
The test is carried out by GB/T6739-1996 pencil determination method for film hardness. Fig. 8 shows the pencil hardness test results of the nano-coating deposited with 2 times of pulling the "mixed solution of 12 ml acid sol solution and 50 ml high concentration hollow sphere" in example 5. After 3H pencil test, the coating has no damage, which indicates that the coating meets the industrial requirement of 3H.
Example 6
Refer to example 4 method for preparing nano coating.
(1) And ultrasonically cleaning the glass sheet in ethanol for 5-30 minutes.
(2) And (2) respectively pulling the cleaned glass sheet obtained in the step (1) for 1,2, 3, 4 and 5 times in a mixed solution of 12 ml of acidic sol solution and 50 ml of 5% hollow sphere ethanol solution in example 3, wherein the pulling speed is 20-200mm/min, soaking the glass sheet in the suspension for 5-50 seconds, and standing the glass sheet indoors for 5-60 seconds after pulling out each time.
The light transmittance of the prepared coating is reduced to 93 percent, which shows that the ultrahigh-concentration hollow spheres are not beneficial to anti-reflection.
Claims (8)
1. The preparation method of the silica hollow sphere nanocomposite is characterized in that the silica hollow sphere nanocomposite is formed by compounding a silica hollow sphere suspension and a silica sol, and the method specifically comprises the following steps:
respectively preparing the silica hollow sphere suspension and the nano silica acid sol;
uniformly mixing the silica hollow sphere suspension and the nano silica acid sol by stirring, standing to obtain the silica hollow sphere nanocomposite, controlling the temperature in standing to be 4-30 ℃, controlling the standing time to be more than or equal to 48 hours,
wherein the particle size of the silica hollow sphere in the silica hollow sphere suspension is 20-120nm, and the shell thickness is 5-15 nm; the nano-silica acid sol has chain-shaped nano-silica, the condensation degree of the nano-silica acid sol is 70-90%, the average length of the chain-shaped nano-silica is 5nm,
the silica hollow sphere suspension is formed by dispersing silica hollow spheres in a solvent, wherein the solvent is at least one selected from ethanol, methanol, isopropanol, propylene glycol and n-butanol; the preparation process of the nano-silica acid sol comprises the following steps: the alkoxysilane is subjected to condensation polymerization under an acidic catalysis condition to form non-particle chain-like nano-silica species, so that the nano-silica acidic sol is formed.
2. The production method according to claim 1, wherein the temperature at the time of standing is controlled to 20 to 25 ℃.
3. A silica hollow sphere nanocomposite, characterized in that it is prepared by the method according to claim 1 or 2.
4. A method for preparing a silica hollow sphere nano-coating, which is characterized in that the nano-coating is prepared on the surface of a substrate by performing at least one pulling operation on the substrate by using the silica nano-composite material according to claim 3,
wherein the thickness of the silica hollow sphere nano coating is 50-200 nm;
wherein the light transmittance of the silicon dioxide hollow sphere nano coating is more than or equal to 95 percent;
wherein the contact angle of the silicon dioxide hollow sphere nano coating is less than or equal to 8 degrees;
wherein the hardness of the silicon dioxide hollow sphere nano coating is more than or equal to 3H.
5. The method of claim 4, wherein the substrate is glass, and the glass is solar glass, window glass, mirror glass, or automotive glass.
6. The method for preparing according to claim 4, characterized in that said at least one pulling operation comprises in particular the steps of:
immersing the substrate in the silicon dioxide hollow sphere nano composite material, then pulling, standing,
wherein, the pulling speed of the substrate is controlled to be 20-200mm/min during immersion; controlling the immersion time to be 5-50 s; standing for 5-60 s indoors after each pulling-out.
7. The silica hollow sphere nano-coating is characterized by being prepared by the preparation method according to any one of claims 4 to 6.
8. A coated glass, wherein the glass substrate is coated with the silica hollow sphere nano-coating according to claim 7,
wherein the glass substrate is solar glass, window glass, mirror glass or automobile glass.
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