Composite heat insulating material containing a highly water-absorbent resin layer

Abstract

The present invention provides a composite insulation material comprising: two or more blankets including a blanket substrate and an aerogel formed inside and on a surface of the blanket substrate; and a superabsorbent polymer layer located between the two or more blankets and including superabsorbent polymer particles.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0085835 filed on July 12, 2022, and all the contents disclosed in the literature of the Korean patent application are incorporated herein by reference in their entirety.

[0002] The present invention relates to a composite heat insulating material, and more particularly, to a composite heat insulating material including a superabsorbent polymer layer (SAP layer) between blankets as heat insulating materials, thereby improving heat insulating performance.

Background Art

[0003] Aerogel is a highly porous material having a porosity of about 90 to 99.9% and a pore diameter in the range of 1 to 100 nm, and has super-insulation showing a high porosity, a large specific surface area, and a lower thermal conductivity than conventional organic insulating materials such as styrofoam, and thus is used for applications of highly efficient heat insulating materials.

[0004] The aerogel is produced by impregnating and gelling a catalyzed sol into a base material for a blanket. Here, in the case of the aerogel, for example, silica aerogel, moisture in the atmosphere is adsorbed on the surface of the blanket and penetrates inside due to hydrophilic silanol groups present on the surface, and as a result, the heat conduction of the blanket increases due to the moisture, and ultimately, a problem of deterioration of heat insulating performance occurs.

[0005] In order to solve the above problem, the hydrophilicity of the surface of the aerogel is modified to hydrophobicity, but in this case as well, the problem of deterioration of heat insulating performance still remains unsolved when exposed to moisture for a long time.

[0006] Therefore, there is a need for a method capable of minimizing the deterioration of the heat insulating performance of the blanket even when moisture penetrates into the blanket.

Summary of the Invention

Problems to be Solved by the Invention

[0007] The problem to be solved by the present invention is to provide a composite heat insulating material with improved heat insulating performance by positioning a highly water-absorbent resin layer between blankets that may have increased heat conduction due to moisture, in order to solve the problems mentioned in the background art of the above invention.

Means for Solving the Problem

[0008] According to one embodiment of the present invention for solving the above problem, the present invention provides a composite heat insulating material including a base material for a blanket and two or more blankets including an aerogel formed inside and on the surface of the base material for the blanket, and a highly water-absorbent resin layer located between the two or more blankets and including highly water-absorbent resin particles. <>

Effect of the Invention

[0009] According to the composite heat insulating material of the present invention, the highly water-absorbent resin particles contained in the highly water-absorbent resin layer located between the blankets have the property of absorbing moisture in the atmosphere. Due to such a property, the moisture in the atmosphere that penetrates into the blanket can be absorbed in advance, and the heat insulating effect can be maximized. Also, even when moisture has already penetrated into the blanket, by absorbing this moisture, the low thermal conductivity of the composite heat insulating material itself can be maintained.

[0010] Also, since the highly water-absorbent resin particles have the property of swelling when absorbing moisture, after absorbing moisture, they can swell and function to protect the blanket from moisture. Such a property can serve as a protective film to prevent moisture from moving deeper into the composite heat insulating material.

Brief Description of the Drawings

[0011]

Figure 1

Mode for Carrying Out the Invention

[0012] In the description and claims of the present invention, terms and words used should not be construed as being limited to their ordinary or dictionary meanings. The inventors should interpret them in accordance with the meaning and concept that conform to the technical idea of the present invention in accordance with the principle that they can appropriately define the concept of the terms in order to explain their invention in the best way.

[0013] Hereinafter, in order to facilitate the understanding of the present invention, the present invention will be described in more detail.

[0014] The composite heat insulating material according to an embodiment of the present invention may include two or more blankets including a base material for a blanket and an aerogel formed inside and on the surface of the base material for the blanket, and a superabsorbent resin layer located between the two or more blankets and including superabsorbent resin particles.

[0015] In the two or more blankets, the base material for the blanket included in the blanket can be a porous base material in terms of improving the heat insulation of the blanket. When the base material for the blanket is porous, the catalyzed sol for forming the aerogel on the inside and surface of the base material for the blanket easily penetrates from the surface to the inside of the base material for the blanket. Therefore, the aerogel can be uniformly formed up to the inside of the base material for the blanket, thereby maximizing the heat insulation effect of the blanket and the composite heat insulating material including the same.

[0016] The base material for the blanket can be a film, a sheet, a net, a fiber matrix, a non-woven fabric, or a laminate of two or more of these. Also, depending on the application, the surface thereof may have a surface roughness formed thereon or be patterned. More specifically, the base material for the blanket can be a fiber matrix that can further improve the heat insulation performance by including voids into which the aerogel can be easily inserted.

[0017] Specifically, the base material for the blanket can be polyamide, polybenzimidazole, polyaramide, acrylic resin, phenolic resin, polyester, polyetheretherketone (PEEK), polyolefin (for example, polyethylene, polypropylene or their copolymers), cellulose, carbon, cotton, wool, hemp, non-woven fabric, glass fiber or ceramic wool. More specifically, the base material for the blanket of the present invention can contain glass fiber (glass felt, glass fiber) with low thermal conductivity and suitable for heat insulating materials.

[0018] The blanket according to an embodiment of the present invention can include an aerogel formed inside and on the surface of the base material for the blanket. The aerogel can be formed in the voids of the base material for the blanket, that is, the voids can be spaces constituted by the three-dimensional matrix structure of the glass fiber. On the other hand, the aerogel formed inside and on the surface of the base material for the blanket can mean an aggregate of aerogels compounded with the base material for the blanket. Specifically, the aerogel formed on the surface of the base material for the blanket means a state where a part is exposed to the outer surface of the blanket and in contact with the atmosphere, etc., and the aerogel formed inside the base material for the blanket can mean an aerogel that exists inside the blanket and is not exposed to the outer surface of the blanket.

[0019] Furthermore, the blanket including the aerogel formed inside and on the surface of the base material for the blanket can be manufactured by impregnating the base material for the blanket with a catalyzed sol and gelling it.

[0020] First, the catalyzed sol can contain a base catalyst and a sol. The sol is a substance that forms a porous gel through a sol-gel reaction and can include an inorganic sol, an organic sol, or a combination thereof. Specifically, the inorganic sol can include zirconia, yttrium oxide, hafnia, alumina, titania, ceria, silica, magnesium oxide, calcium oxide, magnesium fluoride, calcium fluoride, and combinations thereof, and the organic sol can include polyacrylate, polyolefin, polystyrene, polyacrylonitrile, polyurethane, polyimide, polyfurfuryl alcohol, phenol furfuryl alcohol, melamine formaldehyde, resorcinol formaldehyde, cresol formaldehyde, phenol formaldehyde, polyvinyl alcohol dialdehyde, polycyanurate, polyacrylamide, and combinations thereof. More specifically, in terms of ensuring excellent bonding properties with the base material for the blanket and ultimately completing a blanket with low thermal conductivity, silica sol, which is an inorganic sol, can be included.

[0021] Specifically, the silica sol can be produced by mixing a silica precursor, water, and an organic solvent. The silica precursor can contain a silicon-containing alkoxide compound. Specifically, it can contain tetraalkyl silicates such as tetramethyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS), methyl triethyl orthosilicate, dimethyl diethyl orthosilicate, tetrapropyl orthosilicate, tetraisopropyl orthosilicate, tetrabutyl orthosilicate, tetra secondary butyl orthosilicate, tetra tertiary butyl orthosilicate, tetrahexyl orthosilicate, tetracyclohexyl orthosilicate, tetradodecyl orthosilicate, etc. More specifically, it can contain tetraethyl orthosilicate (TEOS).

[0022] The silica precursor can be used in an amount such that the content of silica (SiO2) contained in the silica sol is 3% by weight to 30% by weight. When the content of the silica is less than 3% by weight, the aerogel formed inside and on the surface of the base material for the blanket is too low, and there may be a problem that the desired level of heat insulation effect cannot be expected. When it exceeds 30% by weight, the mechanical properties of the blanket, particularly flexibility, may be reduced due to the formation of excessive aerogel.

[0023] In addition, the silica sol can contain an organic solvent and water, and the organic solvent can be one or more of methanol, ethanol, isopropanol, and butanol in terms of compatibility with the silica precursor and water.

[0024] On the other hand, the base catalyst contained in the catalyzed sol is a substance that increases the pH of the sol and promotes gelation in the gelation step described later. The base catalyst can be an inorganic base such as sodium hydroxide or potassium hydroxide, or an organic base such as ammonium hydroxide. Specifically, it can be sodium hydroxide, ammonia, ammonium hydroxide, or a mixture thereof.

[0025] Next, the catalyzed sol can be impregnated into the substrate for the blanket. Here, impregnation is performed by introducing the fluid catalyzed sol into the substrate for the blanket, whereby it can be shown that the catalyzed sol penetrates into the voids inside and on the surface of the substrate for the blanket.

[0026] The catalyzed silica sol impregnates the substrate for the blanket and gelation occurs, whereby a wet gel-fiber composite is obtained. The gelation can be forming a network structure from the catalyzed sol, and the network structure can be shown as a planar network structure in which a specific polygon with one or more types of atomic arrangements is connected, or a three-dimensional skeletal structure formed by sharing the vertices, corners, and faces of specific polyhedra.

[0027] The gelation can be induced by leaving the catalyzed sol impregnated in the substrate for the blanket for 0.5 to 2.0 hours, and can be carried out within a temperature range of 20°C to 50°C, preferably at room temperature.

[0028] Next, the wet gel-fiber composite is left at an appropriate temperature and can be aged so that chemical changes are completed. Aging can further strengthen the formed network structure and enhance the heat insulation property of the blanket. The aging can be carried out by leaving it at a temperature of 30°C to 70°C for 3 hours to 50 hours.

[0029] According to an embodiment of the present invention, a blanket can form aerogels inside and on the surface of a blanket base material by impregnating, gelling, and aging a catalyzed sol in the blanket base material. Thus, immediately after drying the aerogels formed inside and on the surface of the blanket base material, a low thermal conductivity is maintained. However, the aerogel exhibits vulnerability to moisture due to hydrophilic functional groups present on the surface of the aerogel.

[0030] Hydroxy functional groups present on the surface of the aerogel, for example, in the case of silica aerogel, hydrophilic silanol groups (Si-OH) present on the surface of silica absorb moisture in the atmosphere, resulting in the drawback that the thermal conductivity gradually increases.

[0031] Since the blanket of the present invention is used as a heat insulating material, the above-mentioned drawbacks can be fatal. Therefore, in order to maintain a low thermal conductivity, it is necessary to modify the surface of the aerogel to be hydrophobic and replace the hydrophilic functional groups present on the surface with hydrophobic functional groups.

[0032] In order to modify the surface of the aerogel to be hydrophobic, a surface modifier containing a polar solvent and an organosilane compound can be used. The polar solvent can be methanol, ethanol, or isopropyl alcohol, and the organosilane compound can be trimethylchlorosilane (TMCS), hexamethyldisilazane (HMDS), methyltrimethoxysilane (MTMS), trimethylethoxysilane (TMES), ethyltriethoxysilane (ETES), or phenyltriethoxysilane (PTES). More specifically, it can be trimethylethoxysilane or hexamethyldisilazane.

[0033] Thus, after the aerogel formed by impregnating and gelling the substrate for the blanket is surface-modified and then dried, the aerogel can contain hydrophobic functional groups on its surface. The silica aerogel according to an embodiment of the present invention has a surface substituted with hydrophobic functional groups and excellent heat insulation properties, and a silica aerogel-containing blanket including the same can ensure a low thermal conductivity.

[0034] However, even though the surface of the aerogel is thus substituted with hydrophobic functional groups, ultimately, the thermal conductivity of the blanket may increase and the heat insulation performance may decrease due to long-term moisture exposure. Therefore, as described later, by providing a highly water-absorbent resin layer in the composite heat insulation material of the present invention, deterioration due to moisture, that is, a decrease in the heat insulation performance of the aerogel, can be prevented.

[0035] On the one hand, the blanket according to an embodiment of the present invention is characterized in that the deviation of the thermal conductivity due to the position within one blanket is 3.0 mW / m·K or less, preferably 2.0 mW / m·K or less, or 1.0 mW / m·K or less. Here, those having no difference and having a value of 0, that is, those having the same thermal conductivity within the blanket can also be included in the scope of the present invention.

[0036] Further, the thickness deviation of the blanket can be 1.5 mm or less, 1.2 mm or less, 0.7 mm or less, preferably 0.5 mm or less.

[0037] The deviation of the thermal conductivity and thickness is a characteristic that can be shown by a cut blanket. Specifically, it is the difference between the values measured in the area from both ends at intervals of 30 cm each in an area of 0.01 m 2 ~10.0 m 2 area, more specifically, the difference between the values measured in the area from both ends at intervals of 30 cm each in an area of 0.36 m 2 ~5.0 m 2 area.

[0038] As an example, the thermal conductivity and thickness of the blanket are obtained at predetermined intervals for a plurality of samples having a predetermined size within the blanket. For each sample, the thermal conductivity is measured at room temperature (23 ± 5°C) using an HFM 436 Lambda equipment manufactured by NETZSCH. It can be shown by comparing the values of the thermal conductivity measured in the area from both ends at intervals of 30 cm each for a plurality of samples.

[0039] Here, the number of samples in the blanket can vary depending on the length of the blanket. As an example, it can be 2 to 20, 3 to 10, or 3 to 5.

[0040] Also, according to an embodiment of the present invention, the blanket includes an aerogel and a base material for the blanket. Specifically, the aerogel may be formed inside and on the surface of the base material for the blanket, or a large amount of aerogel particles may be uniformly formed inside and on the surface of the base material for the blanket.

[0041] The blanket can have an improved thermal conductivity of 10 mW / m·K to 20 mW / m·K. Within this range, there is an effect of maximizing the heat insulation property of the blanket. The above thermal conductivity is a value measured at room temperature (23 ± 5°C) by the heat flow method using an HFM 436 Lambda device manufactured by NETZSCH.

[0042] The blanket included in the composite heat insulation material according to an embodiment of the present invention can contain an aerogel. For example, in the case of silica aerogel, as described above, there is a drawback that the thermal conductivity gradually increases due to the hydrophilic silanol groups (Si-OH) present on the surface absorbing moisture in the atmosphere. Therefore, in order to maintain a low thermal conductivity, it is common to modify the surface of the aerogel to be hydrophobic.

[0043] As described above, although the blanket contains silica aerogel with a surface modified to be hydrophobic in order to maintain such a low thermal conductivity, the heat insulation effect cannot be maximized. Because of the hydrophobic treatment, there may be no major problem when exposed to moisture for a short time, but moisture penetration due to long-term moisture exposure ultimately reduces the heat insulation performance of the blanket. Eventually, the hydrophobic treatment cannot be a fundamental solution to moisture.

[0044] Therefore, the composite heat insulation material according to an embodiment of the present invention positions a highly water-absorbent resin layer between the blankets so that the highly water-absorbent resin particles contained in the highly water-absorbent resin layer can absorb moisture in the atmosphere and moisture that has penetrated into the blankets. Since the highly water-absorbent resin particles have the property of absorbing and swelling the moisture around the particles, the performance degradation of the composite heat insulation material can be minimized.

[0045] Specifically, the superabsorbent resin particles can include a crosslinked polymer of a water-soluble ethylenically unsaturated monomer having at least partially neutralized acidic groups and an internal crosslinking agent. Here, the water-soluble ethylenically unsaturated monomer can include (meth)acrylic acid or a salt thereof. For example, when using acrylic acid and / or an alkali metal salt such as its sodium salt as the water-soluble ethylenically unsaturated monomer, superabsorbent resin particles with improved water absorbency can be obtained.

[0046] In addition, examples of the water-soluble ethylenically unsaturated monomer include anionic monomers such as maleic anhydride, fumaric acid, crotonic acid, itaconic acid, 2-acryloylethane sulfonic acid, 2-methacryloylethane sulfonic acid, 2-(meth)acryloylpropane sulfonic acid, or 2-(meth)acrylamide-2-methylpropane sulfonic acid and their salts; nonionic hydrophilic-containing monomers such as (meth)acrylamide, N-substituted (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, or polyethylene glycol (meth)acrylate; and any one or more selected from the group consisting of amino group-containing unsaturated monomers such as (N,N)-dimethylaminoethyl (meth)acrylate or (N,N)-dimethylaminopropyl (meth)acrylamide and their quaternized products.

[0047] On the other hand, the superabsorbent resin particles can include a crosslinked polymer crosslinked by an internal crosslinking agent. The internal crosslinking agent can play a role in crosslinking and polymerizing the unsaturated bonds of the above water-soluble ethylenically unsaturated monomer.

[0048] As the internal crosslinking agent, it can be a (meth)acrylate compound in which a crosslinking reaction is carried out by a free-radical polymerization (FRP) reaction. Specifically, the internal crosslinking agent can be one or more compounds selected from the group consisting of ethylene glycol di(meth)acrylate, polyethylene glycol (meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polypropylene glycol (meth)acrylate, butanediol di(meth)acrylate, butylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, hexanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate. More specifically, among them, it can be polyethylene glycol di(meth)acrylate.

[0049] The crosslinked polymer of the present invention can be produced by a polymerization reaction of a composition containing a water-soluble ethylenic unsaturated monomer, an internal crosslinking agent, and a polymerization initiator. Here, in the composition, the internal crosslinking agent can be 0.01 to 5 parts by weight based on 100 parts by weight of the water-soluble ethylenic unsaturated monomer. For example, the internal crosslinking agent can be 0.01 part by weight or more, 0.05 part by weight or more, 0.1 part by weight, or 0.2 part by weight or more, and 5 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, or 0.5 part by weight or less based on 100 parts by weight of the water-soluble ethylenic unsaturated monomer. When the content of the internal crosslinking agent is too low, crosslinking is not sufficiently carried out, and it is difficult to achieve a strength above an appropriate level. When the content of the internal crosslinking agent is too high, the internal crosslinking density becomes high, and it is difficult to achieve the desired water retention ability.

[0050] In addition, the superabsorbent resin particles of the present invention can include a surface crosslinked layer on the surface. Here, the surface crosslinked layer can be crosslinked from a surface crosslinking agent, and the surface crosslinking agent includes a polyvalent epoxy compound, and the polyvalent epoxy compound can be a glycidyl ether compound of a polyhydric alcohol.

[0051] Specifically, the surface crosslinking agent can contain one or more polyvalent epoxy compounds selected from the group consisting of ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, triethylene glycol diglycidyl ether, tetraethylene glycol diglycidyl ether, glycerin polyglycidyl ether, and sorbitol polyglycidyl ether.

[0052] The surface crosslinking agent can be about 0.001 to about 5 parts by weight based on 100 parts by weight of the base resin described later. Specifically, the surface crosslinking agent can be about 0.005 parts by weight or more, about 0.01 parts by weight or more, about 0.05 parts by weight or more, and about 4 parts by weight or less, about 2 parts by weight or less, or about 1 part by weight or less based on 100 parts by weight of the base resin. When the content of the surface crosslinking agent is too low, the crosslinking density of the surface crosslinked layer is too low, and absorption characteristics such as absorption capacity may decrease under pressure. When the content of the surface crosslinking agent is too high, an excessive surface crosslinking reaction occurs, and it is difficult to suppress the rewetting phenomenon of the superabsorbent resin particles.

[0053] On the one hand, the particle size (D50) of the superabsorbent resin particles contained in the composite heat insulating material of the present invention can be 10 to 850 μm. Usually, when the particle size of the superabsorbent resin particles is 150 μm or less, they are classified as fine powder, and when it is more than 150 μm and 850 μm or less, they are classified as normal particles. Here, generally, normal particles are mainly commercialized, while the composite heat insulating material in the present invention utilizes the characteristics of superabsorbent resin particles that absorb moisture and swell by themselves, so it is independent of the particle size. Therefore, the superabsorbent resin particles of the present invention can further contain fine powder particles in addition to normal particles. The particle size can be measured using the laser diffraction method.

[0054] The method for manufacturing the superabsorbent resin particles is described step by step as follows. First, a polymerization reaction of the composition is carried out. The composition can contain the above-mentioned water-soluble ethylenically unsaturated monomer and internal crosslinking agent, and a polymerization initiator, and optionally, can further contain additives such as a thickener, a plasticizer, a storage stabilizer, and an antioxidant.

[0055] The composition can form a water-containing gel polymer by a polymerization reaction. In the step of drying and pulverizing the water-containing gel polymer, in order to improve the drying efficiency, a step of coarsely pulverizing the water-containing gel polymer before drying can be included. As described above, drying is performed on the water-containing gel polymer immediately after polymerization with or without passing through the coarsely pulverizing step. Then, the dried polymer obtained through the drying step can be pulverized to perform a step of manufacturing a base resin.

[0056] Next, in the presence of a surface crosslinking agent, a surface crosslinking reaction step of forming a surface crosslinked layer on at least a part of the surface of the base resin is performed. Generally, the surface crosslinking agent is applied to the surface of the base resin. Therefore, the surface crosslinking reaction is carried out on the surface of the base resin, which improves the crosslinking property on the surface of the base resin without substantially affecting the inside of the particles. Therefore, the surface crosslinked base resin has a higher degree of crosslinking near the surface than inside. By heating the base resin added with the surface crosslinking agent, the surface crosslinking reaction and drying can be carried out simultaneously.

[0057] After the surface crosslinking, a step of classifying the base resin on which the surface crosslinked layer is formed can follow. The base resin can be completed into superabsorbent resin particles through processes such as pulverization and classification. Then, the superabsorbent resin particles are classified according to the particle size, and superabsorbent resin particles with an appropriate particle size for the intended use can be commercialized.

[0058] The superabsorbent resin particles can have a water retention capacity (CRC) measured according to the EDANA method WSP 241.3 of 24 g / g or more, or 25 g / g or more, or 26 g / g or more, and in the range of 40 g / g or less, 38 g / g or less, or 36 g / g or less.

[0059] Also, the superabsorbent resin particles can have a pressure absorption capacity (AUP) at 0.7 psi measured according to the EDANA method WSP 242.3 of 18 g / g or more, or 20 g / g or more, or 22 g / g or more, and 27 g / g or less, or 25 g / g or less.

[0060] Since the superabsorbent resin particles contained in the superabsorbent resin layer basically have the property of absorbing moisture in the air, the moisture in the air that penetrates into the blanket can be absorbed in advance. Also, the moisture that has already penetrated into the blanket is absorbed by the superabsorbent resin particles, so that the reduction in the heat insulation performance of the composite heat insulation material can be minimized.

[0061] To describe in detail the composite heat insulating material according to an embodiment of the present invention, referring to FIGS. 1(a) and 1(b) below, the composite heat insulating material 1 can have a structure in which the superabsorbent resin layer 3 and the blankets 2 are alternately laminated between the blankets 2. In the case of FIG. 1(a), the composite heat insulating material 1 has a structure in which one superabsorbent resin layer 3 is laminated between the blankets 2. In the case of FIG. 1(b), the composite heat insulating material 1 has a structure in which the superabsorbent resin layer 3, the blanket 2, and the superabsorbent resin layer 3 are alternately laminated in this order between the blankets 2, and two superabsorbent resin layers 3 are laminated. That is, one or more surfaces of the blanket 2 that serve as a heat insulating material in the composite heat insulating material 1 can be in contact with the superabsorbent resin layer 3, and the superabsorbent resin particles contained in the superabsorbent resin layer 3 have the property of being able to absorb moisture corresponding to up to 50 times their own weight. Therefore, it plays an excellent role in minimizing the moisture in the blanket 2 which is a heat insulating material. Also, even when the superabsorbent resin particles absorb moisture, the decrease in the thermal conductivity of the composite heat insulating material 1 due to the moisture absorption can be small. That is, due to the good moisture absorption characteristics of the superabsorbent resin particles, it is possible to suppress the increase in the thermal conductivity of the blanket 2 due to moisture, and since the degree of increase in the thermal conductivity due to the moisture-absorbed superabsorbent resin layer 3 is not large, the increase in the thermal conductivity of the composite heat insulating material 1 itself due to moisture is prevented, and thereby, it is possible to maintain good heat insulating performance.

[0062] Referring to FIGS. 1(a) and 1(b) below, in the composite heat insulating material 1 of the present invention, the superabsorbent resin layer 3 can be located between the two or more blankets 2. The superabsorbent resin layer 3 can be a coating layer formed on the blanket 2, or can be a filling layer in which superabsorbent resin particles are filled in a breathable receptor. Specifically, the superabsorbent resin layer 3 according to an embodiment of the present invention can include a breathable receptor and the superabsorbent resin particles filled in the breathable receptor.

[0063] In the case of the coating layer, it can be formed by applying a coating liquid prepared by stirring and mixing the superabsorbent resin particles with a dispersion solvent and a binder onto the blanket 2 and drying it.

[0064] In the case of the filling layer, it can be formed by filling the superabsorbent resin particles into another breathable receptor, sealing the breathable receptor, and then placing and pressing it between the two or more blankets 2.

[0065] Specifically, since the superabsorbent resin particles exist in the form of powder, they have the characteristic of scattering like dust. Even when the superabsorbent resin layer 3 is applied as a coating layer together with a binder, the superabsorbent resin particles may separate and scatter separately due to the weak adhesive force between some of the superabsorbent resin particles on the surface of the composite heat insulating material. Therefore, the superabsorbent resin layer 3 is preferably applied in the form of a filling layer.

[0066] Therefore, the breathable receptor can be a net-like structure through which moisture and air can pass without the superabsorbent resin particles passing through. Here, the breathable receptor can include nylon, glass fiber / Polyethylene (PE), non-woven fabric materials, and biodegradable materials (for example, Poly Lactic Acid; PLA).

[0067] According to an embodiment of the present invention, the breathable receptor includes two or more suture lines intersecting each other and a receiving portion defined by the suture lines, and the superabsorbent resin particles can be received in the receiving portion. The suture line is a line that stitches across the breathable receptor, and when the suture line is generated, a receiving portion, which is a space where the superabsorbent resin particles can be received, is generated. The receiving portion can form a number of square or rectangular forms when viewed from the plane of the breathable receptor.

[0068] When the air-permeable receptor is filled with superabsorbent resin particles without a suture line and a storage part, the superabsorbent resin particles in the air-permeable receptor may be filled unevenly within the area of the air-permeable receptor. For example, when the plate-shaped composite heat insulating material is set vertically and applied as a heat insulating material, the superabsorbent resin particles may be concentrated downward due to gravity, resulting in an uneven distribution of the superabsorbent resin particles. Therefore, by forming partitions of the storage part through two or more suture lines intersecting with each other and filling the storage part with superabsorbent resin particles, even when the composite heat insulating material is set vertically and applied vertically, the superabsorbent resin particles can be uniformly accommodated within the air-permeable receptor.

[0069] According to an embodiment of the present invention, the basis weight of the superabsorbent resin layer can be 0.08 to 0.31 g / cm 2 and more specifically can be 0.15 to 0.25 g / cm 2 The basis weight means the ratio of the total mass of the superabsorbent resin particles contained in the superabsorbent resin layer to the area of the superabsorbent resin layer. Therefore, by including the mass of the superabsorbent resin particles within the above range in the superabsorbent resin layer according to the area of the superabsorbent resin layer, the moisture absorption performance of the superabsorbent resin layer can be maximized.

[0070] Specifically, when the basis weight is 0.08 g / cm 2 or more, the superabsorbent resin layer can appropriately absorb the moisture that penetrates into the blanket in the composite heat insulating material and the moisture that penetrates into the atmosphere, thereby reducing the humidity or moisture content of the composite heat insulating material itself. Thereby, it is possible to prevent a decrease in the heat insulating performance of the composite heat insulating material in a moisture atmosphere.

[0071] When the basis weight is 0.31 g / cm 2 or less, for example, it is possible to prevent a decrease in the heat insulating performance of the entire composite heat insulating material due to the superabsorbent resin layer being formed with an excessive specific gravity or thickness.

[0072] On the one hand, the superabsorbent resin particles contained in the superabsorbent resin layer of the present invention have the property of swelling when absorbing moisture. That is, the separated superabsorbent resin particles can swell while absorbing the surrounding moisture and the moisture that has penetrated into the composite heat insulating material, and a protective film can be formed. The protective film can play a role in preventing the penetrated moisture from continuously moving deeper into the interior following the surface of the composite heat insulating material. In addition, it can also play a role in buffering to prevent damage to the composite heat insulating material from external impacts and preventing moisture penetration due to damage to the blanket. Even if the blanket is damaged, the protective film can prevent excessive moisture from penetrating into the blanket.

[0073] According to an embodiment of the present invention, the ratio of the thickness of the superabsorbent resin layer to the total thickness of two or more blankets can be 0.025 to 0.1. When the ratio of the thickness exceeds 0.1, the superabsorbent resin layer may swell excessively and be formed thickly, resulting in a lower heat insulation effect of the composite heat insulating material. Instead, a decrease in thermal conductivity may be caused by excessive moisture in the composite heat insulating material itself. When the ratio of the thickness is less than 0.025, the effect of the superabsorbent resin layer, which attempts to maintain the heat insulation effect of the composite heat insulating material by absorbing moisture that adversely affects the heat insulation of the blanket with a somewhat thin superabsorbent resin layer, may not be significant.

[0074] The ratio of the total thickness of the superabsorbent resin layer to the total thickness of the two or more blankets may, for example, mean the ratio of the thickness of the superabsorbent resin layer to the sum of the thicknesses of two blankets when one superabsorbent resin layer is located between two blankets. Here, the thickness can be measured with a vernier caliper.

[0075] Hereinafter, the present invention will be described in more detail by way of examples. However, it is obvious to those skilled in the art that the following examples are for illustrating the present invention, and various changes and modifications are possible within the scope of the present invention and the scope of the technical idea, and the scope of the present invention is not limited only to this.

[0076] Examples Example 1 (1) Production of Blanket Tetraethyl orthosilicate (TEOS) and water were mixed at a molar ratio of 1:4, ethanol having a weight ratio of 1:5 to TEOS was added to produce a silica sol, and a base catalyst was introduced into the silica sol to produce a catalyzed sol.

[0077] Glass fibers were placed as a base material for the blanket in a reactor filled with the catalyzed sol, and the silica sol was impregnated into the base material for the blanket. After leaving it at room temperature for 1 hour to gel and obtain a wet gel - fiber composite, the temperature was raised to 60 °C and then left for 24 hours for aging.

[0078] Next, a solution prepared by diluting trimethylethoxysilane to 40% by volume in ethanol (water content 8% by weight) was prepared as a surface modifier. The surface modifier was introduced into the reactor, and hydrophobic treatment was carried out at 60 °C for 24 hours to form an aerogel with hydrophobic functional groups inside and on the surface of the base material for the blanket.

[0079] Finally, oven drying was carried out at 150 °C and normal pressure for 1 hour to produce a plate - shaped blanket with a thickness of 10 mm.

[0080] (2) Production of Superabsorbent Resin Particles In a 3L glass container equipped with a stirrer and a thermometer, 100 g (1.388 mol) of acrylic acid, 0.26 g of polyethylene glycol diacrylate (PEGDA) as an internal cross - linker, 0.008 g of diphenyl(2,4,6 - trimethylbenzoyl)phosphine oxide as a photopolymerization initiator, 0.20 g of sodium persulfate as a thermal polymerization initiator, and 123.5 g of 32% caustic soda solution were mixed with water at room temperature so that the solid content was 45.0% by weight to produce a composition.

[0081] Next, the composition was supplied onto a conveyor belt with a width of 10 cm and a length of 2 m rotating at a speed of 10 cm / min. Here, the polymerization reaction was carried out on the conveyor belt equipped with a light source for 20 minutes, whereby a hydrogel polymer with a water content of 45% by weight was obtained.

[0082] Next, the hydrogel polymer was ground using a meat chopper so as to become particles having a particle size of 300 μm to 5000 μm. Then, the ground product was dried using an Air-flow oven with hot air at 185°C for 30 minutes. Through the grinding, drying, and classification, a base resin was obtained.

[0083] After a surface cross-linking solution obtained by mixing water, methanol, and ethylene glycol diglycidyl ether which is a surface cross-linking agent was added to 100 g of the base resin, a surface cross-linking reaction was carried out at 198°C. Then, this was ground and classified to produce superabsorbent resin particles with a particle size of 10 to 850 μm.

[0084] (3) Production of superabsorbent resin layer 10 g of the superabsorbent resin particles produced in the production of the superabsorbent resin particles were filled into a plate-shaped air-permeable receiver having an area of 64 cm 2 (length 8 cm × width 8 cm). After this was made horizontal, the filled superabsorbent resin particles were uniformly distributed. Then, it was sewn with one suture line in the length direction and one suture line in the width direction of the air-permeable receiver, and by the intersection of these suture lines, four accommodating portions were partitioned. In such a state that the superabsorbent resin particles were uniformly accommodated in a large number of accommodating portions partitioned by the generation of such suture lines, a superabsorbent resin layer having a basis weight of 0.16 g / cm 2 and a thickness of 1 mm was produced.

[0085] (4) Production of composite heat insulation material The 10 mm thickness and 144 cm prepared by the production of the blanket 2The high water-absorbing resin layer was laminated on a plate-shaped blanket with an area of (12 cm in length × 12 cm in width). After laminating a blanket identical to the above-mentioned blanket on the laminated high water-absorbing resin layer and then pressing, the blanket and the high water-absorbing resin layer were adhered to each other. In this way, the thickness of the high water-absorbing resin layer was 1 mm between the two blankets, and the basis weight was 0.16 g / cm 2 and it was positioned. Accordingly, a composite heat insulating material was manufactured in which the ratio of the total thickness of the high water-absorbing resin layer to the total thickness of the two blankets was 0.05.

[0086] Example 2 Except that the amount of the high water-absorbing resin particles filled in the high water-absorbing resin layer used in Example 1 was 20 g and the basis weight of the high water-absorbing resin layer was 0.31 g / cm 2 a composite heat insulating material was manufactured using the same method as in Example 1.

[0087] Example 3 In Example 1, except that after filling the high water-absorbing resin particles into a plate-shaped air-permeable receptor and not forming two or more suture lines intersecting with each other, that is, except for not partitioning another accommodating portion, a composite heat insulating material was manufactured using the same method as in Example 1.

[0088] Example 4 Except that the amount of the high water-absorbing resin particles filled in the high water-absorbing resin layer used in Example 1 was 3 g and the basis weight of the high water-absorbing resin layer was 0.05 g / cm 2 a composite heat insulating material was manufactured using the same method as in Example 1.

[0089] Example 5 Except that the amount of the high water-absorbing resin particles filled in the high water-absorbing resin layer used in Example 1 was 25 g and the basis weight of the high water-absorbing resin layer was 0.39 g / cm 2 a composite heat insulating material was manufactured using the same method as in Example 1.

[0090] Comparative Example Comparative Example 1 A composite insulation material was manufactured in the same manner as in Example 1, except that a superabsorbent polymer layer was not used and a single-layer blanket having a thickness of 20 mm was used.

[0091] Experimental example The thermal conductivity of the composite heat insulating materials produced in Examples 1 to 5 and Comparative Example 1 was measured by the following method, and the results are shown in Table 1 below.

[0092] [Table 1]

[0093] Samples of the composite insulation materials manufactured in Examples 1 to 5 and Comparative Example 1 were prepared, and the weights of the samples were measured using an AND WBA-6200 High-precision Balance (0.01 g to 6200 g). In addition, the thermal conductivity of the samples was measured at room temperature (23±5°C) using a NETZSCH HFM 436 Lambda instrument.

[0094] Then, the composite insulation sample was placed in a thermo-hygrostat to absorb moisture at a temperature of 80°C and a humidity of 95%. The weight and thermal conductivity of the sample in the humidified state were measured as described above.

[0095] As shown in Table 1, the thermal conductivity of the composite insulation materials of the Examples and Comparative Examples before moisture absorption was the same. However, after exposure to moisture absorption conditions, the thermal conductivity of Experimental Examples 1 to 5 was low, confirming that excellent insulation performance was maintained. Therefore, it was confirmed that the presence of a superabsorbent polymer layer can maximize the insulation performance of the composite insulation material. Furthermore, it was confirmed that the moisture absorption properties of the superabsorbent polymer layer can minimize moisture penetration into the blanket within the composite insulation material.

[0096] In addition, Experimental Examples 6 and 7 show the results of measuring thermal conductivity, which is the insulating effect, for a composite insulating material manufactured from Comparative Example 1 that does not have a superabsorbent polymer layer, when the material was allowed to absorb moisture under the same conditions in a thermo-hygrostat (Experimental Example 6), and when the composite insulating material was immersed in a thermostatic bath at 25°C and fixed with a weight to prevent it from floating above the water surface (Experimental Example 7). Experimental Examples 6 and 7 showed increases in thermal conductivity of 44% and 196% compared to before moisture absorption, confirming a significant decrease in insulating ability compared to Experimental Example 1, which had a superabsorbent polymer layer.

Claims

1. A composite heat insulating material comprising a base material for a blanket and two or more blankets including an aerogel formed inside and on the surface of the base material for the blanket, and a superabsorbent resin layer located between the two or more blankets and containing superabsorbent resin particles, wherein the superabsorbent resin layer includes a breathable receptor and the superabsorbent resin particles filled in the breathable receptor, and the superabsorbent resin particles include a crosslinked polymer of a water-soluble ethylenically unsaturated monomer having at least partially neutralized acidic groups and an internal crosslinking agent.

2. The composite heat insulating material according to Claim 1, wherein the blanket and the superabsorbent resin layer are alternately laminated.

3. The breathable receptor includes two or more suture lines intersecting with each other and an accommodation part partitioned by the suture lines, and the superabsorbent resin particles are accommodated in the accommodation part. The composite heat insulating material according to Claim 1.

4. The basis weight of the superabsorbent resin layer is 0.08 to 0.31 g / cm ２ The composite heat insulating material according to any one of claims 1 to 3, which is such.

5. The composite heat insulating material according to any one of Claims 1 to 3, wherein the ratio of the total thickness of the superabsorbent resin layer to the total thickness of the two or more blankets is 0.025 to 0.

1.

6. The composite heat insulating material according to Claim 1, wherein the aerogel includes a hydrophobic functional group on the surface.

7. The composite heat insulating material according to Claim 1, wherein the water-soluble ethylenically unsaturated monomer includes (meth)acrylic acid or a salt thereof.

8. The composite heat insulating material according to Claim 1, wherein the particle size of the superabsorbent resin particles is 10 to 850 μm.

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