TWI593793B - Core material for vacuum insulation panel and method for fabricating vacuum insulation panel using the same - Google Patents

Description

Core material for vacuum insulation material and vacuum insulation material using the core material for vacuum insulation material and preparation thereof method

The present invention relates to a core material for a vacuum heat insulating material formed of a melamine resin-cured foam, and a vacuum heat insulating material using the core material for the vacuum heat insulating material and a method for producing the same.

The vacuum heat insulating material is generally prepared by using an inorganic compound having a low thermal conductivity and a low gas generation rate like a glass fiber as a core material, and coating it with a bag formed of a composite plastic laminated film excellent in gas barrier properties. After the exterior is externally decompressed, the laminated portion between the gas barrier films is heat-sealed to prepare a vacuum insulation material for the heat insulating material of the electronic product. The existing glass fiber cotton used as a core material of a vacuum heat insulating material is prepared by collecting cotton by bulky glass fibers and by a thermocompression bonding process, and uses this as a core material, and therefore, in preparation When the vacuum insulation material is used, the insulation performance of 0.45 W/mK can be ensured.

However, when glass fiber cotton is used as a core material of a vacuum insulation material, although excellent initial thermal performance can be ensured, when it is used for a long period of time, the gas which is transmitted through the outer skin material film increases the thermal conductivity and has long-term durability. The problem of reduced sex. Conversely, When the glass fiber board is used as a core material for a vacuum heat insulating material for a long period of time, gas transfer is minimized by gas through a small pore diameter of the glass fiber sheet, and therefore, it has an advantage of excellent long-term durability, but has The disadvantage of the initial thermal insulation performance decline.

As a result, in the case of using the glass fiber cotton as a core material in the conventional vacuum heat insulating material, since the long-term durability is lowered and the life is short, it is suitable not only for a building that requires a life of more than 10 years. In the field, there is a problem in terms of reliability. When it is applied to the field of home appliances, there is also a problem of reliability. When a glass fiber board is used as a core material, since the preparation unit has a high unit price and the molding property is lowered, it is There are limitations in the application of thermal insulation materials, and therefore, the research necessity for materials for core materials for vacuum insulation materials is increasing.

An embodiment of the present invention provides a core material for a vacuum insulation material which is excellent in monovalent cost and excellent in heat insulation performance and long-term durability.

Still another embodiment of the present invention provides a vacuum insulation material which minimizes a heat transfer path, thereby making the heat insulation performance excellent, achieving a reduction in total weight, and a wide variety of utilization rates.

An embodiment of the present invention provides a core material for a vacuum heat insulating material formed of a melamine resin cured foam having an open cell content of 80% or more.

The above melamine resin cured foam may comprise bubbles having an average particle diameter of from about 50 μm to about 500 μm.

The melamine resin cured foam may have a compressive strength of from about 1.2 kgf/cm ² to about 5.0 kgf/cm ² .

The above melamine resin cured foam may comprise a three-dimensional network skeleton structure.

The above skeleton structure may not include a bubble wall.

A further embodiment of the present invention provides a vacuum insulation material comprising: a core material formed of the melamine resin cured foam; and a sheath material for vacuum packaging the core material.

The vacuum insulation material may further include an absorbing material attached or inserted into the core material to have a moisture absorption rate of about 25% or more.

The outer skin material may include a laminated structure of a surface protective layer, a metal barrier layer, and an adhesive layer in this order from the outside.

The surface protective layer may have a layer structure of a polyethylene terephthalate (PET) and nylon (nylon) film, and the metal barrier layer may be formed of an aluminum foil (Foil), and the adhesive layer may be selected from a high density poly Ethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), cast polypropylene (CPP), oriented polypropylene (OPP), polyvinylidene chloride (PVDC), polyvinyl chloride ( One or more of the group consisting of PVC), ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl alcohol copolymer (EVOH), and combinations thereof.

The surface protective layer and the metal barrier layer, and between the metal barrier layer and the adhesive layer may be bonded by a polyurethane (PU)-based resin, respectively.

In another embodiment of the present invention, a method for preparing a vacuum insulation material is provided, the method for preparing the vacuum insulation material comprising the steps of: preparing the melamine resin-cured foam core material; and the core material at about 50 ° C a step of removing the residual material by applying a pressure of about 0.5 Pa to about 10 Pa to a temperature of about 250 ° C for about 10 minutes to about 200 minutes; The step of vacuum packaging after coating the core material with a sheath material.

The vacuum insulation material described above can be used as a core material compared to ordinary glass fiber cotton, which can save the preparation unit price and has the advantage of excellent long-term durability. Also, the heat transfer path is minimized, so that the heat insulating performance is less than about 0.03 W/mK, which is excellent.

Further, the above method for preparing a vacuum insulation material can provide a vacuum insulation material capable of minimizing an organic compound discharged from a melamine foam to prevent a decrease in vacuum degree, and no outgassing occurs (out gassing) ), the thermal insulation performance is not reduced, so that it can be used for at least about 10 years.

100‧‧‧ core material

110‧‧‧ bubbles

200‧‧‧Skin material

300‧‧‧absorbing materials

210‧‧‧Surface protection layer

220‧‧‧Metal barrier

230‧‧‧Adhesive layer

Fig. 1 is a schematic view showing a core material for a vacuum insulation material according to an embodiment of the present invention.

Fig. 2 is a schematic view showing the structure of a core material for a vacuum insulation material according to an embodiment of the present invention.

Part (a) of Fig. 3 and part (b) of Fig. 3 are cross-sectional views showing a vacuum insulation material according to an embodiment of the present invention.

Fig. 4 is a cross-sectional view showing a sheath material included in a vacuum insulation material according to an embodiment of the present invention.

Hereinafter, embodiments of the invention will be described in detail. However, the above embodiments are merely illustrative, and the present invention is not limited thereto, and the present invention is defined only by the scope of the patent application.

In order to accurately describe the present invention, parts that are not related to the description are omitted, and In the text, the same reference numerals are attached to the same or similar structural elements.

In the drawings, the thickness is enlarged in order to clearly indicate the respective layers and regions. Further, in the drawings, the thickness of a part of layers and regions is shown enlarged for convenience of explanation.

Hereinafter, an arbitrary structure is formed in the "upper (or lower)" of the substrate or "upper (or lower)" of the substrate, not only means that any structure is formed in contact with the upper surface (or lower surface) of the substrate, but also The representation is not limited to the inclusion of other structures between any of the structures formed on (or below) the substrate and substrate described above.

Core material for vacuum insulation material

In an embodiment of the present invention, a core material for a vacuum heat insulating material formed of a melamine resin cured foam having an opening ratio of 80% or more is provided.

Fig. 1 is a schematic view showing a core material for a vacuum insulation material according to an embodiment of the present invention. Referring to Fig. 1, the core material 100 for vacuum insulation material can be regarded as a block shape including a melamine resin cured foam.

At this time, preferably, the foaming ratio of the bubble 110 is adjusted so that the open cell content of the core material 100 reaches about 80% or more. The above-mentioned opening ratio refers to the ratio of the open-cell bubbles in the bubble formed per unit area. In the present invention, when the opening ratio is less than 80%, not only the subsequent vacuum process time but also the residual gas remains. The melamine resin solidifies the inside of the foam to cause outgassing which occurs after the vacuum heat insulating material is formed.

On the contrary, in the case where the opening ratio reaches 100%, the structural strength is remarkably lowered and the vacuum pressure cannot be withstood, and therefore, the lower limit of the above opening ratio is less than 100%. At this time, the above opening ratio can be measured by ASTM D-2856.

The above melamine resin cured foam may comprise bubbles 110 having an average particle diameter of from about 50 μm to about 500 μm to simultaneously satisfy structural strength and open porosity. In the case where the average particle diameter of the above-mentioned bubbles is less than about 50 μm, the number of bubbles contained in the melamine resin-cured foam increases, and the density of the foam may be increased, and thus the process time becomes long, and degassing may occur. . Further, in the case where the average particle diameter of the bubbles is larger than about 500 μm, there is a problem that the structural strength of the supporting bubbles may be weakened.

Therefore, the average particle diameter of the above-mentioned bubbles is maintained in the above range, which is advantageous for the process conditions and physical properties, and can optimize the vacuum process in which degassing does not occur, and maintain structural strength.

The melamine resin cured foam may have a compressive strength of from about 1.2 kgf/cm ² to about 5.0 kgf/cm ² . The compressive strength is the maximum compressive stress that the material can withstand without being damaged. The compressive strength is measured by compressing 10% of the vacuum insulation material in a direction perpendicular or level to the foaming direction of the melamine resin cured foam. The strength can be measured by ASTM D-1621, JIS A-9514 and KS M-3809.

When the compressive strength of the melamine resin-cured foam is less than about 1.2 kgf/cm ² , there is a problem that the core material formed of the melamine resin-cured foam cannot withstand the vacuum process, and the compressive strength is more than about 5.0 kgf/cm. ^In the case of ² , when the foaming step is performed, the amount of the foaming agent or the composition for forming the melamine resin-cured foam is increased, so that the number of bubbles contained is increased, and the density may be increased, and This increases the vacuum process time so that degassing may occur. Therefore, the compressive strength of the melamine resin-cured foam described above is maintained in the above range, and the structural strength subjected to the vacuum process step can be achieved.

The above melamine resin cured foam may comprise a three-dimensional network skeleton structure. three The mesh-like skeleton structure refers to a structure in which a planar network structure connecting a specific polygon or a vertex, an angle, a surface, or the like of a specific polyhedron is shared to form a three-dimensional skeleton structure, for example, the above-described three-dimensional network skeleton structure A skeletal structure formed by a pentagon and a hexagonal surface may be included as a fullerene carbon structure.

Fig. 2 is a schematic view showing the structure of a core material for a vacuum heat insulating material according to an embodiment of the present invention, and the melamine resin cured foam is formed of a three-dimensional network skeleton structure. Specifically, the skeleton structure of the above melamine resin-cured foam may not have a bubble wall.

In the case where the skeleton structure includes a cell wall, not only the heat transfer by the convection inside the foam of the melamine resin solidification but also the path of transferring heat through the cell wall is shortened, so that the heat conductivity is increased, thereby possibly lowering Thermal insulation performance. Also, it is possible to lengthen the vacuum process time, resulting in a decrease in productivity.

For example, the above melamine resin cured foam may be a melamine-formaldehyde foam, and this may be prepared by a method of extruding a solution containing a melamine-formaldehyde preliminary condensate and a foam by an extruder. Specifically, the above solution was discharged through a die, and the above solution was immediately heated to be expanded to prepare a melamine-formaldehyde foam having a skeleton structure of a bubble wall. As the above-mentioned foam, as a physical foam, a hydrocarbon, a halogenated fluorinated hydrocarbon, or CO ₂ can be used.

Vacuum insulation material

According to still another embodiment of the present invention, there is provided a vacuum insulation material comprising a core material for a vacuum insulation material and a sheath material, wherein the core material for the vacuum insulation material is cured by a melamine resin having an open cell content of 80% or more. The body material is formed by vacuum-packing the core material.

Further, the vacuum insulation material may include a core material formed of the melamine resin-cured foam as described above and a sheath material for vacuum-packing the core material, and the vacuum insulation material may further include adhesion or insertion into the above. The absorbent material of the core material. The absorbing material is for preventing generation of gas and moisture inside the sheath material due to external temperature changes.

The above absorbent material may be formed of quicklime (CaO) and a pouch containing quicklime. The quicklime powder having a purity of 95% or more is used, and the pouch is formed of crepe paper and polypropylene (PP) impregnated nonwoven fabric to ensure moisture absorption performance of 25% or more. At this time, preferably, the thickness of the absorbing material is within about 2 mm in consideration of the total thickness of the vacuum insulation material.

Part (a) of Fig. 3 and part (b) of Fig. 3 are cross-sectional views showing a vacuum insulation material according to an embodiment of the present invention. Part (a) of Fig. 3 shows a vacuum insulation material in a state in which the outer surface material 200 is sealed in a state where the absorbent material 300 is adhered to the surface of the core material 100, and part (b) of Fig. 3 shows A vacuum heat insulating material in a state of being sealed with the outer skin material 200 in a state where the absorbent material 300 is inserted into the inside of the core material 100.

The outer skin material is a bag body that covers the core material for the vacuum heat insulating material, and its specific shape and preparation method will be described below. Fig. 4 is a cross-sectional view showing a sheath material included in a vacuum insulation material according to an embodiment of the present invention.

Referring to Fig. 4, in the sheath material 200, first, a metal barrier layer 220 and a surface protective layer 210 are sequentially formed on the upper portion of the adhesive layer 230. The adhesive layer 230 can be defined as a layer formed inside the bag body, and the surface protective layer 210 can be defined as a layer exposed at the outermost periphery.

Further, the adhesive layer 230 is a layer which is thermally welded to each other by heat sealing, and functions to maintain a vacuum state. Therefore, the adhesive layer 230 is selected from the group consisting of high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and flow, which are easy to be thermally welded. Polypropylene (CPP), oriented polypropylene (OPP), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl alcohol copolymer (EVOH) and The thermoplastic plastic film is formed of one or more of their combined compositions, and the thickness of the adhesive layer 230 is preferably from about 1 μm to about 100 μm to provide sufficient sealing properties.

Then, a metal thin film having a thickness of about 6 μm to about 7 μm is formed on the upper portion of the adhesive layer 230 as the barrier layer 220 for the gas barrier and the protective core. At this time, the aluminum foil (Foil) metal barrier layer 220 is most commonly used. At present, a film having more excellent characteristics than the aluminum foil has not appeared, and therefore an embodiment of the present invention also uses an aluminum foil. At this time, since aluminum is a metal material, problems such as cracking during bonding occur, and in order to prevent such a problem, the surface protective layer 210 is formed on the upper portion of the metal barrier layer 220.

The surface protective layer 210 of the above sheath material may be a polyethylene terephthalate (PET) film or a polyvinylidene chloride (PVDC)/polyethylene terephthalate (PET) having a thickness of about 10 μm to about 14 μm. A film and a laminated structure of a nylon (Nylon) film having a thickness of about 20 μm to about 30 μm are formed. In this case, in the case where the degree of crack generated in the metal barrier layer 220 is severe, the polyethylene terephthalate/nylon film may be damaged, and in order to prevent such a phenomenon, A vinyl resin layer is applied to the upper portion of the polyethylene terephthalate layer.

The vinyl resin layer may be selected from the group consisting of polyvinyl chloride (PVC), polyvinyl acetate (PVA), polyvinyl alcohol (PVAL), polyvinyl butyral (PVB), polyvinylidene chloride (PVDC), and One or more of the vinyl resins in their combined composition. Meanwhile, in order to further improve the airtightness of the sheath material, the surface protective layer 210, the metal barrier layer 220, and the adhesive layer 230 may be bonded to each other using a polyurethane (PU) resin. The sheath material 200 is thus formed such that the above vacuum insulation material has optimum airtightness and long-term durability.

Vacuum insulation material preparation method

In another embodiment of the present invention, there is provided a method for preparing a vacuum insulation material, the method for preparing the vacuum insulation material comprising the steps of: preparing a melamine resin cured foam having an open cell content of 80% or more. a step of using a core material for a vacuum insulation material; a step of applying a pressure of 0.5 Pa to 10 Pa at a temperature of 50 ° C to 250 ° C for 10 minutes to 200 minutes to remove residual substances; and using a sheath material The step of vacuum packaging after covering the above core material.

The core material formed of the melamine resin-cured foam is formed by mixing a melamine-formaldehyde resin, a curing agent, a foaming agent, and other additives at a high speed and curing at a temperature higher than normal temperature, and As a product of the reaction, not only water but also residual monomers remain, and therefore, the probability of outgassing occurring in the vacuum packaging step or after preparation is very high.

Therefore, before the vacuum packaging step, a pressure of from about 0.5 Pa to about 100 Pa is applied to the core material at a temperature of from about 50 ° C to about 250 ° C for an application time of from about 10 minutes to about 200 minutes to remove residue. A degassed compound such as a monomer (formaldehyde, residual phenol and water) or VOC (volatile organic compound). Further, since the method for producing the vacuum heat insulating material can minimize the gas and moisture generated in the core material, the absorbent material as described above can be omitted. At the same time, the melamine resin-cured foam has an open porosity of about 80% or more, and therefore, a high porosity (about 50% or more) can be maintained after the preparation, so that excellent performance can be exhibited.

A number of specific embodiments of the invention are set forth below. However, the various embodiments described below are merely intended to illustrate or illustrate the invention, and the invention is not limited thereby.

Examples and comparative examples Example 1

The melamine resin cured foam having an average particle diameter of the bubble of 100 μm, an opening ratio of 95%, and a compressive strength of 1.5 kgf/cm ² was made into a vacuum of 8 × 190 × 250 mm (thickness × width × length) and used as a vacuum. Core material for insulation materials. Then, a skin is formed from a polyvinylidene chloride (PVDC)/polyethylene terephthalate film (PET) film of 12 μm, a nylon (Nylon) film of 25 μm, an aluminum foil of 7 μm, and a linear low-density polyethylene (LLDPE) film of 50 μm. material. Next, 25 g of quicklime (CaO) having a purity of 95% was placed in a pouch to prepare two absorbent materials and inserted into the surface of the core material. Thereafter, all of the residual gas of 5 Pa was discharged at a temperature of 150 ° C, and the core material was inserted into the bag, and then sealed under a vacuum of 10 Pa to prepare a vacuum heat insulating material of the present invention.

Example 2

The melamine resin cured foam having a bubble average particle diameter of 100 μm, an open cell ratio of 90%, and a compressive strength of 1.2 kgf/cm ² was used as a size of 8 × 190 × 250 mm (thickness × width × length). A vacuum insulation material was prepared under the same conditions as in the above Example 1 except for the core material for the vacuum insulation material.

Comparative example 1

A vacuum insulation material was prepared under the same conditions as in the above Example 1 except that it was made of a glass fiber board and was made into a core material of a vacuum insulation material after being made into a size of 8 × 190 × 250 mm (thickness × width × length).

Comparative example 2

The polyurethane foam having a bubble diameter of 150 μm, an opening ratio of 95%, and a compressive strength of 1.5 kgf/cm ² was used as a vacuum after being made into a size of 8 × 190 × 250 mm (thickness × width × length). A vacuum insulation material was prepared in the same conditions as in the above Example 1 except for the core material for the heat insulating material.

Comparative example 3

The melamine resin cured foam having a bubble average particle diameter of 100 μm, an open cell ratio of 70%, and a compressive strength of 1.5 kgf/cm ² was used as a size of 8 × 190 × 250 mm (thickness × width × length). A vacuum insulation material was prepared under the same conditions as in the above Example 1 except for the core material for the vacuum insulation material.

Experimental example: Determination of thermal conductivity of vacuum insulation materials

The vacuum insulation materials of the above examples and comparative examples were placed in a constant temperature chamber at 85 ° C for 3 months, and compared with the thermal conductivity of the entire heat-insulated vacuum insulation material. At this time, heat was measured using a HC-074-200 (manufactured by EKO Corporation, Japan) heat conductivity meter. Conductivity. Then, the thermal conductivity from the initial stage of the acceleration factor prediction to 10 years was applied, and the result was converted into an adiabatic value (W/mK). The results are shown in Table 2 below.

From this, it is understood that Comparative Example 2 in which a glass fiber sheet is used as a core material for a vacuum heat insulating material, Comparative Example 2 in which a polyurethane foam is used as a core material for a vacuum heat insulating material, and a foamed body in which a melamine resin is cured are used. In Comparative Example 3, which was a core material for a vacuum heat insulating material but having an opening ratio of less than 80%, in the case of Example 1 and Example 2, the initial heat insulating value was low. Further, it was confirmed that the amount of increase in thermal conductivity with time was also significantly lower than that of the plurality of comparative examples.

Therefore, it can be understood that the foam is cured using a melamine resin as a vacuum. In the case of the vacuum heat insulating material of the core material for the heat insulating material, the initial heat insulating property and the long-term durability are excellent, and it is also understood that the melamine resin cured foam is used as the core material for the vacuum heat insulating material by the comparative example 3. In the case of the vacuum heat insulating material, the opening ratio of the core material for the vacuum heat insulating material cannot be ensured to be 80% or more. Therefore, although the compressive strength can be improved, the initial heat insulating performance and the long-term durability against the degassing phenomenon cannot be ensured.

100‧‧‧ core material

110‧‧‧ bubbles

Claims (9)

A core material for a vacuum insulation material, comprising: a melamine resin cured foam having an open cell content of 80% or more; wherein the melamine resin cured foam comprises an average particle diameter of 50 μm to 500 μm The bubbles of the melamine resin cured foam have a compressive strength of from 1.2 kgf/cm ² to 5.0 kgf/cm ² . The core material for a vacuum insulation material according to the above aspect of the invention, wherein the melamine resin cured foam comprises a three-dimensional network skeleton structure. The core material for a vacuum insulation material according to claim 2, wherein the skeleton structure does not include a bubble wall. A vacuum insulation material comprising: a core material formed of the melamine resin cured foam according to any one of claims 1 to 3; and a sheath material for vacuum packaging the core material . The vacuum insulation material according to claim 4, wherein the vacuum insulation material further comprises an absorbing material attached or inserted to the core material and having a moisture absorption rate of 25% or more. The vacuum insulation material according to claim 4, wherein the outer skin material comprises a laminated structure of a surface protective layer, a metal barrier layer, and an adhesive layer in order from the outside. The vacuum insulation material according to claim 4, wherein the surface protection layer has a layer structure of polyethylene terephthalate (PET) and nylon (nylon) film, the metal barrier layer is made of aluminum foil ( Foil), the adhesive layer is selected from the group consisting of high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), cast polypropylene (CPP), One of polypropylene (OPP), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl alcohol copolymer (EVOH), and combinations thereof the above. The vacuum insulation material according to claim 6, wherein the surface protective layer and the metal barrier layer are bonded between the metal barrier layer and the adhesion layer by a polyurethane (PU)-based resin. A method for preparing a vacuum insulation material, comprising the steps of: preparing a melamine resin-cured foam core material according to any one of claims 1 to 3; the core material is at 50 ° C The step of applying a pressure of 0.5 Pa to 10 Pa for 10 minutes to 200 minutes to remove residual matter at a temperature of 250 ° C; and a step of vacuum packaging after coating the core material with a sheath material.