KR100741698B1 - Modified aerogel, coating composition comprising it and transparent theraml insulating material therefrom - Google Patents

Abstract

A modified aerogel is provided to produce a transparent thermal insulating material without using a binder for aerogel particles and to form a transparent aerogel coating agent having various physical properties. The modified aerogel is obtained by reacting a metal alkoxide compound with an acryl-containing silane compound in the presence of water and an acid catalyst to obtain a reaction product, and then gelatinizing and maturing the reaction product to be subjected to supercritical drying. The metal alkoxide compound is selected from the group consisting of tetraethoxysilane, tetramethoxysilane, and tetra-n-propoxysilane.

Description

Modified Aerogel, Coating Composition Comprising it and Transparent Theraml Insulating Material Therefrom}

The present invention relates to a surface-modified airgel, a coating agent comprising the same, and a heat insulating material prepared therefrom, and more particularly, to an airgel surface-modified with acrylate, a coating agent comprising the same, and a transparent heat insulating material prepared therefrom. In this way, the insulation provided may be used to impart thermal insulation to a transparent material, such as a glass window.

Aerogel is a transparent or semi-transparent ultra-low density material with a porosity of more than 90% and a specific surface area of several hundred to 1000m ² / g. Therefore, the airgel having such a nanoporous structure can be applied to the field of catalysts, catalyst carriers, soundproofing materials, and the like, and in particular, silica airgel has been spotlighted as a transparent insulating material because of its high light transmittance and extremely low thermal conductivity. It is a very efficient super insulation material that can be used in refrigerators, freezers and heat storage devices.

In general, however, aerogels produced in the form of monoliths, films, or particles show very weak strength, such as brittleness due to high brittleness, which is easily broken by small impacts, and are difficult to process in various thicknesses and shapes. Airgel alone is very difficult to apply as a heat insulating material.

Therefore, in order to solve this problem, a variety of attempts have been made to manufacture a heat insulating material by forming a composite of an airgel and another material, that is, a binder.

In this way, a method of producing a flexible airgel sheet by forming a composite of a fiber or a fibrous web and an airgel such as a nonwoven fabric is known (US 2002/0094426, US 5,789,075, WO96 / 27726, WO97 / 10188). Most of these methods involve impregnating a sol silica solution in a fiber or fibrous web, and then performing a gelation reaction to form an aerogel-fiber composite.

However, in the case of manufacturing the airgel composite using the fiber as described above, the problem caused by the brittleness of the airgel can be solved, but due to the formation of the composite with the fiber loses transparency, which is the main advantage of the airgel insulation only. In addition, when the size and thickness of the insulating material is increased, the drying time increases during the supercritical drying of the airgel, and the difficulty in using a large supercritical device, and the increase in the manufacturing cost due to the application of the airgel composite as an insulating material This is being limited.

In addition, as another method of manufacturing the flexible airgel sheet, a method of preparing a composite of a sandwich form by adding a thermoplastic resin as a binder to the airgel particles has been disclosed (WO98 / 32709, US2003 / 0215640). I have the same problem.

In addition, as modern buildings have a higher proportion of glass windows than in the past, the heat insulating properties of glass windows, which have a relatively high heat loss compared to the walls, are required to be large, and the above-mentioned methods of aerogel insulation by a binder lose transparency. It is difficult to apply (coating) to the window surface and is not suitable as a window insulation.

 The present inventors have completed the present invention as a result of studying to solve the above problems, and an object of the present invention is to provide a surface-modified aerogel, a coating comprising the same, and a transparent insulating material provided therefrom.

The transparent insulation provided in accordance with the present invention is suitable for imparting thermal insulation to transparent materials such as windows, and is provided as an insulation made of 100% aerogel or added without the use of binders for airgel particles as in the prior art. By adjusting the photocurable resin can be prepared a transparent airgel coating of various physical properties.

According to the invention,

A modified airgel is provided which is obtained by gelling and aging a reaction product obtained by reacting a metal alkoxide compound with an acrylic containing silane compound under water and an acid catalyst and then subjecting to supercritical drying.

In addition, according to the present invention, there is provided a coating comprising the modified airgel, photoinitiator and solvent.

Furthermore, according to the present invention, there is provided a transparent heat insulating material to which the coating agent is applied.

Hereinafter, the present invention will be described in more detail.

The present inventors have studied to develop a transparent airgel insulation material, and found that the surface-modified airgel alone can be manufactured as an insulation material while maintaining the insulation properties of the airgel, which is a nanoporous body, to the maximum without using an external binder. . In addition, it was confirmed that the transparent airgel coating agent having various hardness and flexibility can be prepared by adjusting the photocurable resin to be added, thereby completing the present invention.

In one embodiment of the invention, the metal alkoxide and the acrylic containing silane compound are reacted and then gelled and aged and subjected to supercritical drying to provide an airgel surface modified with acrylate.

The sol gel technique for preparing the acrylated aerogels of the present invention may be prepared by any suitable sol gel technique known in the art [R.K. Colloid Chemistry of Silica and Silicates 1954, chapter 6; C.J. Brinker, G.W. Scherer, Sol-Gel Science, 1990, Chaps 2 and 3] can be prepared based on, and will be described in detail below a method for producing an airgel according to the present invention.

First, in order to introduce an acrylate group to the surface of the airgel, the metal alkoxide and the acryl-containing silane compound are mixed in a suitable ratio and then reacted under water and an acid catalyst.

Suitable metal alkoxides used in the preparation of the airgels of the present invention are those having from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms, each of which is not particularly limited to these compounds, but are not particularly limited thereto. TEOS), tetramethoxysilane (TMOS), tetra-n-propoxysilane, aluminum isopropoxide, aluminum-sec-butoxide, cerium isopropoxide, hafnium tert-butoxide, magnesium aluminum isopropoxide , Yttrium isopropoxide, titanium isopropoxide, zirconium isopropoxide and the like can be preferably used. In the present invention, a silane-containing metal alkoxide is preferred, and most preferably tetraethoxysilane may be used.

The acrylic containing silane compound suitably used in the present invention is not particularly limited by this, but alkoxy silyl acrylate is preferable, and is not particularly limited by this, for example, 3-methoxysilylpropyl methacrylate, 3 -Ethoxysilylpropyl methacrylate, 3-methoxysilylpropyl acrylate, 3-ethoxysilylpropyl acrylate and the like are preferable. On the other hand, when preparing a coating agent using a modified airgel alone, a silyl acrylate having butyl, pentyl, hexyl, heptyl, octyl and the like having an alkyl group of 4 or more in length instead of a propyl group is more preferable. Although not limited to this, for example, 3-methoxysilylbutyl methacrylate, 3-ethoxysilylbutyl methacrylate, 3-methoxysilylbutyl acrylate, 3-ethoxysilylbutyl acrylate, 3- Methoxysilylpentyl methacrylate, 3-ethoxysilylpentyl methacrylate, 3-methoxysilylpentyl acrylate, 3-ethoxysilylpentyl acrylate, 3-methoxysilylhexyl methacrylate, 3-ethoxy Silylhexyl methacrylate, 3-methoxysilylhexyl acrylate, 3-ethoxysilylhexyl acrylate, 3-methoxysilylheptyl methacrylate, 3-ethoxysilylheptyl methacrylate, 3-methoxysilylheptyl Acrylate, 3-ethoxysilylheptyl acrylate, 3-methoxysilyloctyl methacrylate, 3-ethoxysilyloctyl methacrylate, 3-methoxysilyloctyl acrylate, 3-ethoxysilyloctyl acrylate, 3-methoxysilylnonyl methac Rate, it is preferable that the 3-ethoxy-silyl-nonyl methacrylate, 3-trimethoxysilyl a nonyl acrylate, nonyl acrylate, or 3-ethoxy-silyl. In this case, the mixing mole ratio of the metal alkoxide and the acryl-containing silane compound is preferably 9: 1 to 1: 9, and when the molar ratio of the acryl-containing silane compound is 1 or less, the photocuring reaction is not efficient and the coating agent Formation is limited, and when the molar ratio of the acrylic-containing silane compound is 9 or more, it affects the physical properties of the airgel.

As described above, the metal alkoxide and the acryl-containing silane compound are mixed, followed by hydrolysis and condensation by adding water and an acid catalyst. At this time, the suitable acid used is not particularly limited, but HCl, H 2 SO 4, or HF is preferable, and most preferably HCl is used. On the other hand, the amount of water added is preferably about 4 to 10 in molar ratio, and the acid is preferably added in a catalytic amount.

As described above, water and a catalyst are added to the mixture of the metal alkoxide and the acrylic silane compound to undergo hydrolysis and condensation to form a "sol" compound, and the sol solution is gelled and aged for a sufficient time. When the gel compound is prepared and tetra (ethoxysilane) is used as the metal alkoxide, and 3- (trimethoxysilyl) propyl methacrylate is used as the acrylic silane compound, the gel compound may be prepared by the following Scheme 1.

Scheme 1

Finally, the gel compound subjected to the sol-gel reaction as described above may be applied to supercritical drying to prepare an aerogel surface-modified with acrylate, in which the supercritical drying is performed using carbon dioxide, and the supercritical drying conditions are Preference is given to performing at 30 to 40 ° C. and 100 bar.

According to another embodiment of the present invention, there is provided a coating comprising an airgel surface modified with acrylate provided as above.

In one embodiment of the present invention, there is provided a coating agent comprising a surface-modified airgel with a acrylate, a photoinitiator and a solvent, and when the coating is coated on a substrate and cured with ultraviolet rays, the acrylate groups attached to the surface of the airgel are mutually It is polymerized and crosslinked, whereby a transparent insulating material consisting of 100% of the airgel without the use of an external binder can be provided.

As a photoinitiator, which is one component of the coating agent according to the present invention, there is no particular limitation thereto, but 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2,4-bistrichloromethyl-6-p -Methoxysteel-s-triazine, 2-p-methoxysteel-4,6-bistrichloromethyl-s-triazine, 2,4-trichloromethyl-6-triazine, 2,4-trichloro Chloromethyl-4-methylnaphthyl-6-triazine, benzophenone, p- (diethylamino) benzophenone, 2,2-dichloro-4-phenoxyacetophenone, 2,2'-diethoxyacetophenone, 2,2'-dibutoxyacetophenone, 2-hydroxy-2-methylproriophenone, pt-butyltrichloroacetophenone, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, bis (2, 4,6-trimethylbenzoyl) phenyl phosphine oxide, 2-methyl thioxanthone, 2-isobutyl thioxanthone, 2-dodecyl thioxanthone, 2,4-dimethyl thioxanthone, 2,4-diethyl tea Oxanthone and 2,2'-bis-2-chlorophenyl-4,5,4 ', 5'-tetraphenyl-2'-1,2'- It may be selected from the group eojineun achieved by an imidazole compound.

The amount of the photoinitiator is preferably added in an amount of 3 to 10% by weight based on the total weight. In this case, when the amount is 3% by weight or less, the curing does not proceed properly or the curing speed is too slow, but 10% by weight In the case of the above, there is a problem that the degree of curing is too high and brittleness increases, or after the reaction, it is present as an unreacted substance to lower physical properties.

In addition, as the solvent of the coating agent, alcohols such as methanol, ethanol, propanol such as isopropyl alcohol, and the like are preferable, and isopropyl alcohol is most preferable.

Optionally, an acrylate monomer, urethane acrylate oligomer or epoxy acrylate oligomer may be further added as a photocurable resin to the coating agent consisting of the surface modified acrylate, photoinitiator and solvent.

The acrylate monomer has one or more acrylate groups, or methacrylate groups, but is not limited to, for example, phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, phenoxy tetraethylene glycol acrylate, phenoxy Cyhexaethylene glycol acrylate, isobornyl acrylate, isobornyl methacrylate, bisphenol ethoxylate diacrylate, ethoxylate phenol monoacrylate, polyethylene glycol 200 diacrylate, tripropylene glycol diacrylate, trimethyl Propane triacrylate, triethylpropane triacrylate, polyethylene glycol diacrylate, ethylene oxide addition type triethyl propane triacrylate, pentaerythritol tetraacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diol acryl Sites, federated pentaerythritol tetraacrylate, may be selected from 2-phenoxyethyl acrylate, ethoxylated bisphenol A diacrylate, federated, or a mixture thereof ethoxylates.

As the photocurable resin, the amount of the acrylate monomer, the urethane acrylate oligomer or the epoxy acrylate oligomer is preferably added in an amount of 10 to 90% by volume based on the total volume. In this case, when the amount is less than 10% by volume, if the airgel is not modified with an acryl group having a long alkyl group, cracks may occur after curing. If the amount is more than 90% by volume, the characteristics of the airgel do not appear. have.

On the other hand, when using the mixture of the said acrylate monomer, urethane acrylate oligomer, or epoxy acrylate oligomer, it is preferable to add in ratio of 1: 9-9: 1.

As described above, when the photocurable resin is selectively added, an additive for improving the physical properties of the final coating agent may be additionally added, and the amount thereof is preferably added within a range that does not change the physical properties of the coating agent. .

Coatings provided according to the present invention may be applied to a transparent substrate, such substrates are not particularly limited, for example, glass, polycarbonate, acrylic resin, PET, TAC, polyvinyl chloride resin, polyamide Plastic sheets or plastic films such as resins and polyimide resins can be used.

The coating agent according to the present invention may be coated on the transparent substrate by a method such as bar coating, spin coating, dip coating, spray coating, etc., and may be cured by irradiating UV rays in a wavelength range of 250-420 nm to provide a final transparent insulating material. The coating technique can be applied by any method known in the art.

The transparent insulating material provided according to the present invention is composed of 100% airgel, which does not require the use of an airgel binder as in the prior art, and because it is transparent, it is possible to replace the insulating material or the glass window of the window, and also useful as a catalyst or a catalyst carrier. Can be used.

Hereinafter, the present invention will be described through examples, which are not intended to limit the present invention.

Example

Example 1

3-trimethoxysilylpropyl methacrylate and tetraethoxysilane were mixed and water was added to the mixture in a molar ratio of 6: 1, followed by hydrochloric acid. It was stirred at room temperature to prepare a sol solution, gelled using a base catalyst NH ₄ OH, and then sealed and aged at 50 ° C. for 24 hours. After aging, solvent replacement of the wet gel was carried out, and supercritical drying was performed at 35 ° C. and 100 bar. This obtained an aerogel whose surface was modified with acrylate.

Example 2

10 g of the airgel obtained in Example 1 is added to 100 ml of isopropyl alcohol, and then mixed through a stirrer to form an airgel evenly dispersed in a solvent. Next, 25.8 g of triethyl propane triacrylate monomer, 60.2 g of urethane acrylate oligomer, and 4 g of 2-hydroxy-2-methyl-1-phenyl-1-propanone were added thereto, followed by sufficiently stirring to prepare an airgel-acrylic coating solution. .

Example 3

The mixed solution obtained in Example 2 was coated on the PET plate by a bar coating method to a thickness of 0.1 ~ 1 mm. The coated PET plate was cured for 20 seconds in a UV curing apparatus of 325 nm wavelength to prepare an airgel-acrylic transparent insulating material. Airgel acrylic insulation showed over 80% transmittance in the visible region.

The transparent insulating material provided according to the present invention is composed of 100% airgel, which does not require the use of an airgel binder as in the prior art, and because it is transparent, it can be used as a heat insulating material or a glass substitute of a glass window, and as a catalyst or a catalyst carrier. It can be usefully used.

Claims (13)

A reaction product obtained by reacting a metal alkoxide compound selected from the group consisting of tetraethoxysilane (TEOS), tetramethoxysilane (TMOS) and tetra-n-propoxysilane with an acrylic containing silane compound under water and an acid catalyst A modified aerogel, characterized in that it is obtained by gelation and maturation followed by supercritical drying. delete The modified aerogel of claim 1 wherein the metal alkoxide compound is tetraethoxysilane. The method of claim 1, wherein the acrylic containing silane compound is 3-methoxysilylpropyl methacrylate, 3-ethoxysilylpropyl methacrylate, 3-methoxysilylpropyl acrylate, 3-ethoxysilylpropyl acrylate, 3-methoxysilylbutyl methacrylate, 3-ethoxysilylbutyl methacrylate, 3-methoxysilylbutyl acrylate, 3-ethoxysilylbutyl acrylate, 3-methoxysilylpentyl methacrylate, 3- Ethoxysilylpentyl methacrylate, 3-methoxysilylpentyl acrylate, 3-ethoxysilylpentyl acrylate, 3-methoxysilylhexyl methacrylate, 3-ethoxysilylhexyl methacrylate, 3-methoxy Silylhexyl acrylate, 3-ethoxysilylhexyl acrylate, 3-methoxysilylheptyl methacrylate, 3-ethoxysilylheptyl methacrylate, 3-methoxysilylheptyl acrylate, 3-ethoxysilylheptyl acrylic Latex, 3-methox Silyloctyl methacrylate, 3-ethoxysilyloctyl methacrylate, 3-methoxysilyloctyl acrylate, 3-ethoxysilyloctyl acrylate, 3-methoxysilylnonyl methacrylate, 3-ethoxysilylnonyl A modified aerogel, characterized in that it is methacrylate, 3-methoxysilylnonyl acrylate, or 3-ethoxysilylnonyl acrylate. The modified aerogel according to claim 1, wherein the mixing ratio of the metal alkoxide and the acryl-containing silane compound is 9: 1 to 1: 9 molar ratio. The modified aerogel of claim 1, wherein the acid catalyst is HCl, H ₂ SO ₄ , or HF. An aerogel-containing coating comprising the modified aerogel, photoinitiator and solvent according to any one of claims 1 and 3. 8. The method of claim 7, wherein the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-propanone, 2,4-bistrichloromethyl-6-p-methoxysteel-s-triazine, 2-p -Methoxysteel-4,6-bistrichloromethyl-s-triazine, 2,4-trichloromethyl-6-triazine, 2,4-trichloromethyl-4-methylnaphthyl-6-triazine , Benzophenone, p- (diethylamino) benzophenone, 2,2-dichloro-4-phenoxyacetophenone, 2,2'-diethoxyacetophenone, 2,2'-dibutoxyacetophenone, 2-hydride Roxy-2-methylproriophenone, pt-butyltrichloroacetophenone, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, bis (2,4,6-trimethylbenzoyl) phenyl phosphine oxide, 2 Methyl thioxanthone, 2-isobutyl thioxanthone, 2-dodecyl thioxanthone, 2,4-dimethyl thioxanthone, 2,4-diethyl thioxanthone, and 2,2'-bis-2- Selected from the group consisting of chlorophenyl-4,5,4 ', 5'-tetraphenyl-2'-1,2'-biimidazole compounds Airgel-containing coating, characterized in that. 8. An aerogel-containing coating according to claim 7, wherein the solvent is isopropanol. 8. An aerogel-containing coating according to claim 7, wherein the coating further comprises an acrylate monomer, urethane acrylate oligomer or epoxy acrylate oligomer. The method of claim 10, wherein the acrylate monomer is phenoxyethyl acrylate, phenoxy diethylene glycol acrylate, phenoxy tetraethylene glycol acrylate, phenoxy hexaethylene glycol acrylate, isobornyl acrylate, isobornyl methacryl Ethylene, Bisphenol Ethoxylate Diacrylate, Ethoxylate Phenolic Monoacrylate, Polyethylene Glycol 200 Diacrylate, Tripropylene Glycol Diacrylate, Trimethyl Propane Triacrylate, Triethyl Propane Triacrylate, Polyethylene Glycol Diacrylate , Ethylene oxide addition type triethyl propane triacrylate, pentaerythritol tetraacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, ethoxylated pentaerythritol tetraacrylate, 2-phenoxy Ethyl acrylic Airgel-containing coating, characterized in that it is selected from the group consisting of ethoxylated bisphenol A diacrylate and mixtures thereof. The transparent heat insulating material to which the coating agent of Claim 7 was applied to the base material. The transparent heat insulating material to which the coating agent of Claim 10 was applied to the base material.