678 results about "Hydrophobic silica" patented technology

The invention belongs to the technical field of a new chemical material, and in particular relates to a high-durability super-hydrophobic self-cleaning coating material and a preparation method thereof. The coating material of the invention is prepared by curing and drying nanoparticles with photo-catalytic activity, a low-surface-free-energy polymer and a cross-linking agent at the room temperature, wherein the low-surface-free-energy polymer consists of one or more of polysiloxane fluoride, dimethyl silicone polymer and polyphenylene methyl siloxane, which contain active groups, such as hydroxyl alkoxy group, carbon-carbon double bond, silanol group, siloxy group, and the like; the cross-linking agent is hydrogen-containing silicone oil or aminosilane; and the mass content of the photo-catalytic nanoparticles in the coating ranges from 10 to 60 percent. The coating is formed into a micro-nanostructure by nanoparticle self-organization; a super-hydrophobic self-cleaning coating with lotus effect is prepared from the coating and a cross-linked filming matrix with low surface energy; the persistence of a lotus-shaped super-hydrophobic characteristic of the coating is realized by using the photo-catalytic decomposition characteristic of an organic pollutant for the nanoparticles; and thus the material is suitable for large-area construction and has high weathering resistance andprominent self-cleaning characteristic.

The present invention discloses a preparation method for hydrophobic silica aerogel with industrial waterglass as a raw material, which comprises the following steps: diluting the industrial waterglass with water; neutralizing with an acid to obtain hydrosol; allowing the hydrosol to stand and age for 8-48 hours at normal temperature so as to form hydrogel; replacing the water in the hydrogel with anhydrous ethanol; allowing the hydrogel to react with organosilane compounds; performing surface modification and simultaneous solvent exchange with n-hexane; suction-filtering; washing; allowing to stand at normal temperature to obtain white hydrophobic silica aerogel powder. The preparation method has simple process and low cost, and the prepared aerogel has porous network-like structure which features a low density and a high specific surface area.

The present invention relates to coating compositions, particularly water-based coating compositions, which incorporate nanotechnology. More specifically, the water-based coating compositions may include: a binder; a plurality of hydrophobic silica particles; and a solvent. The coating compositions may be applied to a variety of different surfaces, such as, for example, metals, plastics and signs, among others to impart resistance to corrosion and/or deterioration over time, as well as good adhesion thereto.

The present invention provides a process for making silica-filled rubber masterbatch using silica hydrophobated with a trimethoxy silane coupling agent that is soluble in an alcohol-water solution containing at least about 70 wt % water. One embodiment uses a mixture of trimethoxy silanes, one or more of which react with rubber to bond the silica to the rubber, and one or more of which do not react with rubber, but do hydrophobate the silica. Hydrophobated silica is mixed with latex polymer and incorporated into rubber during coagulation of the latex, which is preferably coagulated with calcium chloride. The present invention further provides a process for making the trimethoxy silane coupling agents. Preferred trimethoxy silane coupling agents include bis-(3-trimethoxysilylpropyl)-disulfide and bis-(3-trimethoxysilylpropyl)-tetrasulfide. Rubber products, particularly tires, compounded with the inventive silica masterbatch can be processed for a long time before scorching because the silica masterbatch provides a long scorch time.

A curable composition comprising (A) an organopolysiloxane having functional groups capable of condensation reaction at both molecular terminals thereof and (B-1) a hydrophobic silica and a hydrophilic silica. A curable composition comprising (A) an organopolysiloxane having functional groups capable of condensation reaction at both molecular terminals thereof and (B-2) a hydrophobic silica, wherein the hydrophobic silica (B-2) is thermally treated together with the organopolysiloxane (A).

The invention relates to a preparation method of a hydrophobic silica aerogel heat-insulation composite material. The method comprises steps as follows: (1) preparation of silica sol: siloxane is used as a precursor, an organic solvent, water and an acid catalyst are added, and the silica sol is obtained; (2) preparation of composite gel: a flame retardant and an infrared blocking agent are added to the silica sol, the mixture is evenly mixed, a base catalyst is added, an inorganic fiber product is immersed in the silica sol, and the mixture is left to stand; (3) solvent replacement: the composite gel is replaced by the organic solvent; (4) drying: the composite gel is dried. With the adoption of the method, the process is simple, the production cycle is short, the cost is lower, the equipment requirement is low, reaction conditions are controllable, product performance is excellent, and the prepared silica aerogel composite material has the overall waterproof performance, the extremely low heat conductivity coefficient and the excellent high-temperature heat-insulation performance, can pass an incombustibility test under the condition that the material is ensured to be hydrophobic as a whole and reaches level A1 according to the incombustibility test.

The invention provides hydrophobic surface-treated silica particles having (1) a ratio T2:T3 of about 0.4 or more, wherein T2 is the intensity of a peak having a chemical shift in the CP/MAS ²⁹Si NMR spectrum centered within the range of −56 ppm to −59 ppm, and wherein T3 is the intensity of a peak having a chemical shift in the CP/MAS ²⁹Si NMR spectrum centered within the range of −65 ppm to −69 ppm, and (2) a ratio (T2+T3)/(T2+T3+M) of greater than about 0.05, wherein M is the intensity of a peak having a chemical shift in the CP/MAS ²⁹Si NMR spectrum centered within the range of +7 ppm to +18 ppm. The invention also provides a method of preparing hydrophobic surface-treated silica particles.

The invention discloses a thermal-insulation coating by taking hydrophobic silicon dioxide aerogel microspheres as thermal-insulation packing. The coating is prepared by the following main steps: preparing the hydrophobic silicon dioxide aerogel microspheres; and mixing the prepared hydrophobic silicon dioxide aerogel microspheres and a polymer emulsion to prepare the thermal-insulation coating. Hydrophobic modification of the silicon dioxide aerogel microspheres includes the following two modes: in one mode, silicon dioxide wet-gel microspheres are modified by adopting halogenated hydrocarbon and in the other mode, alkoxy silane, silazane or siloxane is added into a mixed solution in a sol preparing stage. When the coating is prepared, a surfactant is added, so that the compatibility between the hydrophobic silicon dioxide aerogel microspheres and the polymer emulsion can be improved, the dispersibility of the microspheres in the coating can be improved, the coating quality can be improved, and the thermal-insulation performance of the coating can be improved.

Disclosed herein is a rapid preparation process of aerogel. More specifically, the present invention relates to a rapid preparation process of aerogel which enables a considerable reduction in preparation time and preparation costs via simultaneous treatment of solvent exchange and surface-modification of hydrophilic-to-hydrophobic transition.

The rapid preparation process comprises mixing a cation exchange resin with sodium silicate (water glass) as a starting material, and removing the sodium ion from the sodium silicate, to subject the sodium silicate to ion exchange; adding a base catalyst and an organosilane compound to the sodium silicate to subject the sodium silicate to gelation; aging the gellized silica gel at room temperature for 2 to 4 hours to discharge water from the silica gel and to modify the surface of the silica gel into hydrophobicity; and drying the hydrophobic silica gel at atmospheric pressure for 18 to 27 hours.

The invention discloses a hydrophobic silica aerogel heat-insulation composite material and a preparation method thereof. The composite material consists of silica aerogel and an inorganic fiber product, wherein the silica aerogel is doped with a flame retardant and an infrared blocking agent. During preparation of sol, siloxane containing hydrophobic groups is introduced, and the content and the distribution state of the hydrophobic groups in a system are controlled by controlling the reactant content and reaction conditions, so that the composite material can pass the test of GB8624-2012 Classification for Burning Behavior of Building Materials and Products (A1-level). The preparation method of the composite material comprises steps as follows: (1) preparation of the silica sol; (2) preparation of composite gel; (3) solvent replacement; (4) drying. With the adoption of the method, the process is simple, the production cycle is short, the cost is lower, the equipment requirement is low, and the prepared silica aerogel composite material has the overall waterproof performance, the extremely low heat conductivity coefficient and the excellent high-temperature heat-insulation performance.

The invention relates to a preparation method of nanometer aerogel heat-insulation coating, which comprises the following steps: dissolving aerogel, solidifying the aerogel, aging, replacing by a surface modification solvent, drying at normal pressure and preparing lyophobic silicon dioxide aerogel; or supercritically drying and preparing hydrophilic silicon dioxide aerogel. The preparation method provided by the invention has the beneficial effects that the aperture of the silicon dioxide aerogel prepared by adopting the method provided by the invention is in nanometer-level distribution, and the main aperture of the silicon dioxide aerogel is10nm and is less than the free path of an air molecular movement, thereby greatly reducing the heat transfer generated by a gas molecular heat movement; the aerogel in the invention is in a network structure formed by overlapping the spherical granules of nanometer silicon dioxide, thereby reducing the contact area of solid granules, increasing the heat transfer path and further achieving the effects of heat maintenance and heat insulation; and lyophobic and hydrophilic type silicon dioxide aerogel can be prepared according to different drying processes to be used by matching organic or inorganic coatings.

The invention discloses a method for quickly preparing hydrophobic silicon dioxide aerogel at low cost. The method comprises the following steps of (S1) mixing a silicon source, water and a surfactant evenly to obtain a precursor solution, adding an acid catalyst to the precursor solution, adjusting the pH value to be 3-4, and then hydrolyzing to obtain sol; and (S2) dropwise adding an alkali catalyst to the sol obtained in the step (S1), continuously stirring in the dropwise adding process, adjusting the pH value to be 6-7, and carrying out gel standing, ageing and ambient pressure drying to obtain the hydrophobic silicon dioxide aerogel. The method is low in cost, free of solvent exchange, short in production cycle and free of environmental pollution; and the prepared hydrophobic silicon dioxide aerogel has good heat preservation and heat insulation properties, hydrophobicity and flexibility.

The invention relates to a preparation method of a hydrophobic silica aerogel composite fiber felt material. The preparation method comprises the following steps: mixing tetraethyl orthosilicate, ethanol, water and an acid catalyst to obtain silica sol; adding an alkali catalyst to the silica sol, uniformly stirring, pouring the mixture into a fiber felt (ceramic or glass fiber felt), immersing, and standing, so as to obtain a gel composite material; ageing the gel composite material in the fiber felt in mother liquor for a certain period of time, and then carrying out solvent exchange, so asto obtain a composite material; immersing the composite material in a solution containing certain concentration of a surface modifier for standing modification, and then drying the composite materialunder atmospheric pressure to obtain the hydrophobic silica aerogel composite fiber felt material. The preparation method has the advantages of simple process, short production cycle, lower cost, lowequipment requirement and excellent product performance, and the hydrophobic silica aerogel composite fiber felt material has superhydrophobic property, strong adsorption property and low thermal conductivity.

A process for producing a hydrophobic silica powder, comprises the steps for hydrophobic treatment of: adding to an aqueous silica sol containing hydrophilic colloidal silica having a specific surface area of 5.5 to 550 m²/g, a disilazane compound represented by formula (1)

(R¹₃Si)₂NH  (1)

wherein each R¹ is C_1-6alkyl group or phenyl group that is selected independently of one another, in an amount of 0.1 to 10 mmol per surface area 100 m² of the hydrophilic colloidal silica, to obtain a first mixture of the aqueous silica sol and the disilazane compound; and heating the mixture at a temperature of 50 to 100° C. for aging it to obtain a slurry as dispersion of hydrophobic treated colloidal silica. The process provides a hydrophobic silica powder through a simple hydrophobic treatment step.

The invention discloses a preparation method of a super hydrophobic coating based on super hydrophobic silica and resin. The resin as a substrate is coated on a glass slide; the super hydrophobic silica is bonded to the resin; and the resin is cured to prepare the super hydrophobic coating. The super hydrophobic coating prepared by the invention is composed of a base resin and a super hydrophobic silica surface layer. The body of the super hydrophobic silica layer is a super hydrophobic material, and if the surface is worn, the coating still has the same super hydrophobic property. When the super hydrophobic coating is polluted, the super hydrophobic function can be recovered by scraping off the surface layer. The super hydrophobic coating provided by the invention also can achieve waterproof effect due to the base resin.

The present invention provides a protective backing sheet for photovoltaic modules. The backing sheet has a layer including fluoropolymer which is cured on a substrate, and the layer includes a hydrophobic silica. The amount of hydrophobic silica contained in the layer is within the range of 2.5 to 15.0% by weight, and preferably in the range of 7.5 to 12.5%. Also, the layer including fluoropolymer may further include a titanium dioxide.

An oil-in-water emulsion useful as a defoamer for pulp and paper mill applications is described. The defoamer has an oil blend (of a triglyceride oil or a mixture of triglyceride oils and silicone), a stabilizing agent (to make the oil blend stable in the emulsion), hydrophobic silica particles, surfactants, dispersants, and other components. The emulsion is usable directly at low concentrations to control foam.

The invention discloses a preparation method of a hydrophobic silica fiber film and a use of the hydrophobic silica fiber film in removal of organic pollutants. The preparation method solves the problem that the existing silica fiber film adsorbs hydrophobic organic pollutants in water difficultly. The preparation method comprises the following steps of preparing silanes with hydrophobic groups and one or more solvents into a silane solution, and immersing a silica nanofiber film in the silane solution for modification so that a hydrophobic group-modified silica nanofiber film is obtained. The hydrophobic groups on surfaces of the silica nanofibers can bind with matrix silica by chemical bonds and thus the hydrophobic silica fiber film has strong adhesion, can be separated and recovered, can be prepared under mild conditions, and can be used as an adsorbent for adsorbing hydrophobic organic pollutants in a water source.