KR20090105576A - Manufacturing method of nearly defectless inorganic nanopowdersol through the supercritical reaction - Google Patents

Abstract

PURPOSE: A method for preparing an inorganic nano-sized body with little defects through a supercritical reaction is provided as an electric/electronic optical functional material owing to its chemically controlled structure. CONSTITUTION: A method for preparing an inorganic nano-sized body with little defects through a supercritical reaction comprises: a first step of dissolving an inorganic precursor in a first solvent; a second step of allowing the inorganic precursor to grow up inorganic nanoparticles through condensation or hydroxylation and obtaining inorganic nanoparticle sol; a third step of adding a second solvent including organic silane to the inorganic nanoparticle sol; and a fourth step of letting the organic silane react to the hydroxyl groups of the inorganic nanoparticle to make them hydrophobic. The first and second steps are performed in supercritical or similar supercritical conditions.

Description

Manufacturing method of nearly defectless inorganic nanopowdersol through the supercritical reaction

The present invention relates to a method for producing an inorganic nano-body, in particular, the process of synthesizing inorganic nano-particles from the inorganic precursor and reacting with an organic silane having a hydroxyl group and a reactive group on the surface of the inorganic nano-particles under supercritical reaction conditions, The present invention relates to a method for producing a low defect inorganic nano-body using a supercritical reaction which can be used as a precise battery electronic photo-functional material due to its low defects and chemical structure control.

Nanomaterials have been tried in various ways in the IT field where technological change and the market is mature. In particular, high performance (high functionality) of materials is unavoidable due to the thinning and high integration of next-generation products such as semiconductors, displays, flexible PCBs, RFID chips, capacitors, flexible solar cells, thin film secondary batteries, and optical control films. As the demand for process technology that can be produced becomes stronger, nano materials that meet the manufacturing conditions of large area, wet roll-to-roll and low-temperature firing are needed.

Recently, the commercial importance of nanomaterials has been highlighted, but it is difficult to satisfy all the required properties as a single material, and conventional composite materials are not utilized as thin film materials for electric and electronic devices due to the limitation of the control of surface properties between materials. .

The organic-inorganic nanohybrid material hybridized at the molecular level satisfies the conditions as a wet process material required for the manufacture of IT products, while the heat resistance, thermal expansion coefficient, thermal conductivity, mechanical properties, electrical properties, It is confirmed that there is a high possibility of satisfying the optical characteristics.

In the organic-inorganic nano-hybrid material, the nanoparticle inorganic material has a hydrophilic hydroxyl group or ions on the surface thereof, and the storage stability is maintained only when the colloidal form is dispersed in water or alcohols or the surfactant is treated, all of which are metal ions, Due to moisture, oxygen, surfactant compounds, etc., it is not a thin film material satisfying the electrical properties.

On the other hand, inorganic nanoparticles are easily synthesized at room temperature in sol form, but they can be calcined at low temperature (below 200 ℃) and have fundamental limitations to satisfy the mechanical properties and various functional properties of thin films. Crosslinking reactions with materials are inevitably required. Organic acids, surfactants, and the like may be used to hydrophobize the surface of the inorganic particles, but the silane coupling agent having an organic group is recommended because of its low temperature reactivity with the inorganic surface and excellent heat resistance, weather resistance, and chemical stability.

In order to satisfy the electrical properties of materials using inorganic nanoparticle sol, studies have been conducted to synthesize high-purity inorganic nanosol by using purification means in a low molecular precursor state such as metal alkoxide, metal nitrate, and metal halide. It is difficult for all hydroxyl groups to participate in the condensation reaction in the process of molecules gathering and sol particle synthesis. In addition, high-purity inorganic sol has almost no ions on the surface, so it is necessary to prevent the aggregation of particles without lean concentration conditions and to hydrophobize the surface and convert it into an organic solvent system for hybridization with a polymer.

In this sol-gel reaction, hydrothermal synthesis is used to increase the condensation completion and crystallinity of inorganic particles, but hydrophobic inorganic sol surface-treated with silane is synthesized and dispersed in organic solvent so that there is no hydroxyl group on the surface of inorganic material having storage stability. Maintaining nanoparticles is not easy.

In addition, it should not be overlooked in the organic-inorganic hybrid material, the particle size (distribution degree), the shape (spherical, plate-like, fibrous), the chemical structure (crystallinity, condensation completion degree), etc. of the inorganic particles should be able to be adjusted and the hydrophobic surface Satisfaction such as treatment, reactive introduction for hybridization, storage stability and processability of the hybrid sol is essential.

In order to solve the above problems, the present invention proceeds in the process of synthesizing the inorganic nanoparticles of low defects or the reaction of the hydroxyl group and the reactive organosilane on the surface of the inorganic nanoparticles under supercritical reaction conditions to reduce the internal defects and surface reaction Method to prepare low defect inorganic nanoparticles sol using supercritical reaction to prepare inorganic nanoparticles sol with excellent storage stability by dispersing moisture, permeation and adsorption, well dispersed in most organic solvents and polymer solutions Is the solution.

In order to solve the above problems, the present invention includes a first step of dissolving an inorganic precursor in a first solvent to grow into inorganic nanoparticles through a hydroxylation reaction and condensation reaction of hydroxyl groups to form an inorganic nanoparticle sol; A second step of adding a second solvent containing an organic silane to the inorganic nanoparticle sol in the first step to cause the organic silane to react with a hydroxyl group on the surface of the inorganic nanoparticle to hydrophobize the surface of the inorganic nanoparticle; However, the first step or the second step is a technical gist of the method for producing a low defect inorganic nano-body using a supercritical reaction, characterized in that proceeding under supercritical or pseudosupercritical reaction conditions.

In addition, the supercritical or pseudosupercritical reaction conditions are realized by injecting inorganic nanoparticle sol into a continuous supercritical reactor or a batch supercritical reactor according to the progress of the first step or the second step. It is preferable.

Here, in the supercritical reactor in which the inorganic nanoparticle sol is injected, it is preferable that a stirring process by a blade to prevent secondary aggregation between particles and a dispersion process by fine beads are realized.

In addition, the inorganic nanoparticles sol of the second step, the inorganic nanoparticles sol of the first step into a supercritical reactor, and injected with liquefied carbon dioxide (CO ₂ ), after the supercritical or pseudosupercritical state It is preferably synthesized by injecting the organosilane dissolved in the second solvent.

Further, after the second step, a high boiling point organic solvent having a relatively higher boiling point than the second solvent is added to the resultant in the second step to prepare a hydrophobized organic solvent-dispersed inorganic sol, or the second step The third step of preparing a hydrophobized inorganic nanoparticles by spraying the resultant in the; It is preferable that the high boiling point organic solvent, NMP, formamide, DMF, glycol ethers, cerussolves, acetates and It is preferable that it is any one or mixtures of ketones.

In addition, the inorganic precursor in the first step is any one of a metal alkoxide, metal nitrate and metal halide, the inorganic nanoparticles synthesized from the inorganic precursor is preferably a metal oxide or a mixture of the metal oxide.

The inorganic nanoparticles may be any one of silica, alumina, magnesium oxide, titania, zirconia, tin oxide, zinc oxide, BaTiO ₃ , ZrTiO ₃ , a compound thereof, and a surface modified thereof with silica. As for the shape of particle | grains, it is preferable that any one or these shapes are mixed among a particulate form, an island form, and a plate form.

In addition, the first solvent in the first step, using any one of water, alcohol and a mixed solution thereof, the second solvent in the second step, alcohol, tetrahydrofuran (THF, tetrahydrofuran), It is preferable to use either low molecular ketones or alkyl halides.

In addition, the organosilane is preferably an organosilane having any one of chemical reactors of vinyl, epoxy, acryl, -OH, -H, amino and thiol, or a 1-3-valent organosilane having alkyl, fluoroalkyl, or phenyl groups. Do.

Herein, the inorganic nanobody is preferably dissolved in a cooled reactive monomer or oligomer and then uniformly dispersed in the reactive monomer and oligomer by removing a solvent.

Inorganic nanoparticles according to the present invention have low defects, that is, they contain little hydroxyl groups or water molecules in the particles, and the reaction with organic silanes on the surface is also carried out precisely, which excludes permeation and adsorption of water, and most organic solvents. B. It is well dispersed in polymer solution, so it has little additional chemical change, making it an organic-inorganic nano-hybrid solution with excellent storage property, electrical and electronic insulating material, optical application functional material, metal protective coating material, ultra durable coating material, high dispersion gas shielding coating material requiring heat resistance. There is an effect that can be applied to the field, impregnant, binding agent, adhesive.

1 is a flowchart illustrating a method for preparing a low defect inorganic nanobody using a supercritical reaction according to the present invention, and FIG. 2 is an organosilane (methyltrimethoxysilane) prepared through the supercritical reaction according to the present invention. TEM photograph of the surface-treated low defect sol silica nano-body.

The present invention is largely composed of a first step of synthesizing inorganic nanoparticles from an inorganic precursor and forming an inorganic nanoparticle sol, and a second step of hydrophobizing the surface of the inorganic nanoparticles contained in the inorganic nanoparticle sol with an organic silane. Any one or all of the first step and the second step is made in a supercritical reaction condition, and relates to a method for producing a low defect inorganic nano-body. Herein, inorganic nano bodies are prepared in various phases as necessary, such as particulate or sol.

In general, the synthesis of inorganic nanoparticles sol under normal temperature or hydrothermal synthesis conditions is difficult to control the particle size, there are many defects (unreacted hydroxyl group), and there are limitations in terms of surface energy control. If the inorganic nanoparticles synthesis and surface hydrophobization reaction proceeds under the conditions, the inorganic nanoparticles sol having low defects can be synthesized in a short time.

First, the first step is carried out at room temperature or supercritical reaction conditions, using the metal alkoxide, metal nitrate, or metal halide type compounds as the inorganic precursor, these materials in the acid or base conditions the first When dissolved in a solvent, that is, water or alcohol or a mixed solvent thereof, the inorganic precursor is hydrated and condensed to grow into inorganic nanoparticles to form an inorganic nanoparticle sol.

Inorganic nanoparticles that can be synthesized from the inorganic precursors are all metal oxides including silica, alumina, magnesium oxide, titania, zirconia, tin oxide, zinc oxide, BaTiO ₃ , ZrTiO _3, and compounds thereof, and are surface modified with silica. Other minerals may be included. At this time, the shape of the inorganic nanoparticles may have a fibrous or plate shape in addition to the particulate.

In addition, the second step is carried out at room temperature or supercritical reaction conditions, the second solvent in the inorganic nanoparticle sol, that is, alcohol, tetrahydrofuran ((THF, tetrahydrofuran), low molecular ketones or organosilane in the alkyl halide) The dissolved solution is added to react with hydroxyl groups on the surface of the inorganic nanoparticles to hydrophobize the surface of the inorganic nanoparticles.

Herein, the organosilane may be an organosilane having any one of chemical reactors of vinyl, epoxy, acryl, -OH, -H, amino, and thiol, or an organosilane with 1-3 having alkyl, fluoroalkyl, and phenyl groups. use.

The addition of the organosilane is to form the inorganic nanoparticles synthesized from the inorganic precursor in a hydrophobic sol state in order to stably disperse in the organic solvent, the preferred method is to control the inorganic nanoparticles sol to an acid between pH 2 ~ 6 Then, an organic silane diluted with alcohols or tetrahydrofuran is added to allow the hydroxyl group on the surface of the inorganic nanoparticle to react with the organic silane to hydrophobize the surface of the inorganic nanoparticle.

Then, the reaction medium is organic solvent by adding an organic solvent while removing water, where the organic solvent is NMP (N-methyl-2-pyrrolidinone), formamide, DMF (dimethylformamide), glycol ethers, Solves, acetates, ketones and the like are used, and the organosilane uses a silane having various organic reactive groups (vinyl, epoxy, acryl, -OH, -H, amino, thiol) when hydrophobizing inorganic nanoparticles.

Here, the supercritical reaction conditions may be any one or both of the step of forming inorganic nanoparticles, the first step of forming a hydroxyl group from the inorganic precursor, and the second step of performing a surface hydrogenation reaction with the organosilane, or at least a second step. In the second phase, it is realized.

Supercritical states are fluids that are neither liquids nor gases above the critical temperature and the critical pressure. Supercritical fluids have diffusion and penetration rates close to those of gases. The reaction solvent of water and alcohol also has a characteristic that the surface energy is greatly lowered when it is in the supercritical state, so that the condensation reaction accompanying the growth of inorganic nanoparticles and the surface reaction with silane proceed in a short time. In addition, when the temperature or pressure does not reach the supercritical state is a pseudo-supercritical state in which the two phases are mixed, it is used when viscosity control is required for dispersion.

The supercritical reaction condition is to add the selected supercritical reaction solvent to the inorganic precursor or the growing inorganic nanoparticles sol using a pressurized pump in accordance with the progress of the first step or the second step to inject into the supercritical reactor In this case, preheating by a heater is generally required.

As the supercritical reactor, a continuous or batch supercritical reactor may be used. In order to prevent secondary aggregation between particles while using the supercritical reactor, stirring by a blade and fine beads are performed. It is desirable that the dispersion process take place. In addition, as the supercritical reaction solvent, any one or a mixture of water, alcohols, carbon dioxide, methylene chloride (CH ₂ Cl ₂ ), and tetrahydrofuran (THF) may be used.

Next, in the second step, the surface of the inorganic nanoparticle is hydrophobized, and then, for removal of the second solvent including water, an organic solvent having a higher boiling point or a monomer or oligomer having a higher boiling point than the second solvent is added to the sol phase. The third step is to prepare a hydrophobized organic solvent dispersed inorganic sol or to hydrophobize the surface of the inorganic nanoparticles in the second step and then spray the same to prepare particulate inorganic nanoparticles. As the high boiling point organic solvent, any one or a mixed solvent of NMP, formamide and DMF, glycol ethers, cerussolves, acetates and ketones are used.

That is, supercritical inorganic nanoparticles sol may be sprayed at high temperature and high pressure to obtain inorganic nanoparticles, and when a high boiling point solvent is contained, low boiling point solvents are separated to obtain an organic solvent dispersed inorganic sol solution. will be. Figure 1 schematically shows a method for producing a low defect inorganic sol or inorganic nanoparticles using a supercritical reaction according to the above process.

In addition, the low-defect inorganic nanoparticles prepared under the supercritical reaction conditions are dissolved in the cooled reactive monomer or oligomer and then the solvent is removed to uniformly disperse the reactive monomer and oligomer.

Hereinafter, the experimental data measured through the specific examples will be described.

FIG. 2 illustrates the use of alkoxysilane as an inorganic precursor, thereby synthesizing silica nanoparticle sol, using ethanol as the first solvent and the second solvent, and ethanol and liquefied carbon dioxide (CO ₂ ) as the supercritical reaction solvent. As the organosilane, the particle size and dispersion state of the low defect sol-like silica nanoparticles prepared using methyltrimethoxysilane are shown in a TEM photograph. Here, the supercritical reaction conditions are about 150 ° C. and about 10 MPa in the case of the supercritical reaction solvent.

As shown, it can be seen that the particle size has an even particle distribution around 20 nm and the dispersion state is evenly dispersed by hydrophobicity through the surface treatment of the functional organosilane.

Table 1 shows the surface water repellency characteristics of the functional organic silanes of the functional organic silanes of the silica-polymer organic-inorganic hybrid coating film using the low defect sol silica nano bodies surface-treated with the functional organic silanes prepared through the supercritical reaction according to the present invention. The contact angle results for.

<Table 1>

Coating film Contact angle Acrylic Polymeric Resin Coating Film To 64 ^o Silica-Polymer Organic / Inorganic Hybrid Coatings Using Silica Nanobody Surface-treated with Phenyltrimethoxysilane through Supercritical Reaction To 103 ^o Silica-Polymer Organic / Inorganic Hybrid Coatings Using Silica Nanobody with Methyltrimethoxysilane Surface Treated by Supercritical Reaction To 95 ^o Silica-Polymer Organic / Inorganic Hybrid Coatings Using Silica Nanobody Surface-treated with Vinyltrimethoxysilane by Supercritical Reaction To 95 ^o Silica-Polymer Organic-Inorganic Hybrid Coatings Using Silica Nanobody Surface-treated with Acrylic Trimethoxysilane by Supercritical Reaction To 78 ^o Silica-Polymer Organic / Inorganic Hybrid Coatings Using Silica Nanobody with Surface Treatment of Epoxytrimethoxysilane Through Supercritical Reaction To 78 ^o

As shown in Table 1, as well as the production of low-density silica nanostructures through a supercritical reaction, it can be seen that the organosilane was ideally treated on the surface of the silica nanostructures, and thus the contact angle was well differentiated.

In addition, Table 2 is a measurement of the moisture shielding properties of the silica-polymer organic-inorganic hybrid coating film using a low-defect sol silica nano body prepared through the supercritical reaction according to the present invention.

<Table 2>

Coating film Moisture shielding properties PET (Polymeric Flexible Film) ~ 10 ² g / m ² * day Silica-polymer organic-inorganic hybrid coating film using a silica nanobody surface-treated with methyltrimethoxysilane (coated on a flexible polymer PET film) ~ 10 ⁰ g / m ² * day Silica-polymer organic-inorganic hybrid coating film using a silica nanobody surface-treated with methyltrimethoxysilane through a supercritical reaction (coated on a flexible polymer PET film) ~ 10 ^-1 g / m ² * day

As shown in Table 2, the water-shielding property of the silica-polymer organic-inorganic hybrid coating film using the low-defect silica nanobody surface-treated with the functional organic silane through the supercritical reaction was performed at room temperature with the conventional flexible polymer film PET. It can be seen that the shielding properties are improved compared to the organic-inorganic coating film using the prepared silica nano-body.

Inorganic nanoparticles prepared in this way, that is, inorganic nanoparticles or organic solvent dispersion inorganic sol have less uncondensed internal defects, so that the crystal structure can be easily controlled, and dense reaction with silane on the surface allows secondary aggregation of inorganic nanoparticles. Minimize the reaction with the silane at the inorganic interface while minimizing.

In order to prepare an organic-inorganic hybrid sol using the inorganic nanoparticle sol, the organic silane is added to and dissolved in a polymer resin capable of a curing reaction with the reactive group of the organosilane. The polymer resin includes a curable resin capable of chemical bonding between molecules or a polymer resin having a high molecular weight mixed in these resins. When hydrophobic inorganic nano sol is mixed with polymer resin, it becomes organic-inorganic hybrid sol solution, and after coating and drying, inorganic nano particle and polymer resin are mutually bonded at molecular level.

       As a result, the present invention can easily remove metal ions or ionic compounds at different material interfaces, and can have thin film coating properties and high performance coating properties without deteriorating insulation through water absorption during use. Applications are greatly expected.

In addition, the organic-inorganic hybrid sol solution using the present invention is coated and dried to form a transparent coating film, when applied to a film or polymer sheet to improve the surface properties (hardness, moisture resistance, thin film roughness, surface energy), metal foil or When applied to a plate, it is possible to prevent oxidation corrosion. In addition, when used as an insulating material for displays, semiconductors, high-integration electronic components, and electric heating facilities, the film can be thinned and has excellent characteristics such as heat resistance, moisture and oxygen blocking, and long-term reliability of electrical insulation. In addition, it is expected to be used as an advanced coating material and paint having environmental friendliness, high temperature long-term reliability, chemical stability (weather resistance), wear resistance, and high adhesive strength.

1-a flow chart for a method for producing a low defect inorganic nano-body using a supercritical reaction according to the present invention.

FIG. 2-TEM photograph of a low defect sol silica nanobody surface-treated with an organosilane (methyltrimethoxysilane) prepared through a supercritical reaction according to the present invention.

Claims (12)

Dissolving an inorganic precursor in a first solvent to grow inorganic nanoparticles through hydroxylation and condensation of hydroxyl groups to form inorganic nanoparticles sol; A second step of adding a second solvent containing an organic silane to the inorganic nanoparticle sol in the first step to cause the organic silane to react with a hydroxyl group on the surface of the inorganic nanoparticle to hydrophobize the surface of the inorganic nanoparticle; But The first step or the second step is a method for producing a low defect inorganic nano-body using a supercritical reaction, characterized in that proceeding under supercritical or pseudo-supercritical reaction conditions. According to claim 1, wherein the supercritical or pseudosupercritical reaction conditions, Low defect inorganic material using a supercritical reaction, which is realized by injecting inorganic nanoparticles sol into a continuous supercritical reactor or a batch supercritical reactor according to the progress of the first step or the second step. Method for producing nanobody. The supercritical reaction according to claim 2, wherein in the supercritical reactor into which the inorganic nanoparticle sol is injected, a stirring process by a blade to prevent secondary aggregation between particles and a dispersion process by fine beads are realized. Method for producing a low defect inorganic nano-body using. According to claim 1, wherein the inorganic nanoparticles sol of the second step, The inorganic nanoparticles sol of the first step is put into a supercritical reactor, liquefied carbon dioxide (CO ₂ ) is injected into a supercritical or pseudosupercritical state, and then an organic silane dissolved in the second solvent is injected. Method for producing a low defect inorganic nano-body using a supercritical reaction, characterized in that synthesized. The method of claim 1, wherein after the second step: Hydrophobized inorganic sol was prepared by adding a high boiling point organic solvent having a relatively higher boiling point than the second solvent to the resultant in the second step, or by spraying the resultant in the second step. The third step of preparing the nanoparticles; Method for producing a low defect inorganic nano-body using a supercritical reaction, characterized in that further made. The method of claim 5, wherein the high boiling organic solvent, NMP, formamide, DMF, glycol ethers, cerules, acetates and ketones, any one or a mixture thereof, the method for producing a low defect inorganic nano-body using a supercritical reaction. According to claim 1, wherein the inorganic precursor in the first step is any one of metal alkoxide, metal nitrate and metal halide, inorganic nanoparticles synthesized from the inorganic precursor is characterized in that the metal oxide or a mixture of the metal oxide. A method for producing a low defect inorganic nanobody using a supercritical reaction. The method of claim 1, wherein the inorganic nanoparticles, Silica, alumina, magnesium oxide, titania, zirconia, tin oxide, zinc oxide, BaTiO ₃ , ZrTiO ₃ , compounds thereof, and surface modifications thereof with silica, wherein the shape of the inorganic nanoparticles is particulate, fibrous and Method for producing a low-defect inorganic material nano-body using a supercritical reaction, characterized in that any one of the plate shape or these shapes are mixed. The method of claim 1, wherein the first solvent in the first step, Method for producing a low defect inorganic nano-body using a supercritical reaction, characterized in that any one of water, alcohol and a mixed solution thereof. The method of claim 1, wherein the second solvent in the second step, Method for producing a low defect inorganic nano-body using a supercritical reaction, characterized in that any one of alcohol, tetrahydrofuran, low molecular ketones and alkyl halide. The method of claim 1, wherein the organosilane, Using an organic silane having a chemical reactor of any one of vinyl, epoxy, acryl, -OH, -H, amino and thiol, or a 1-3-valent organic silane having alkyl, fluoroalkyl, or phenyl groups. Method for producing inorganic defects of low defects. The inorganic nano-body according to any one of claims 1 to 11, A method for producing a low defect inorganic nanobody using a supercritical reaction, characterized in that the inorganic nanobody homogeneously dispersed in the reactive monomer and the oligomer after dissolving in a cooled reactive monomer or oligomer.

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