Composite heat insulation material, method of manufacturing composite heat insulation material, and refrigerator

Abstract

To provide a heat insulation material having excellent heat insulation properties and strength.SOLUTION: A composite heat insulation material includes an aerogel-containing melamine foam sheet including melamine foam and aerogel. and a polyurethane foam sheet laminated on a surface of at least one surface of the aerogel-containing melamine foam sheet.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a composite insulating material, a manufacturing method for the composite insulating material, and a refrigerator. [Background technology]

[0002] Polyurethane foam is widely used as a heat insulating material for refrigerators. It is desired that the heat insulating property of the heat insulating material for refrigerators be further improved. It is known that an aerogel-containing melamine foam sheet containing melamine foam and aerogel has high heat insulating property (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-521670 A Summary of the Invention [Problem to be solved by the invention]

[0004] It is desirable for an insulating material used in a refrigerator to maintain high insulating properties for a long period of time. However, the strength of an aerogel-containing melamine foam sheet is weak, and the insulating properties may decrease due to breakage, cracks, or loss of the aerogel.

[0005] The present invention has been made in consideration of the above circumstances, and has an object to provide an insulating material having excellent insulation properties and strength, a manufacturing method thereof, and a refrigerator with high insulation properties that uses the insulating material. [Means for solving the problem]

[0006] The present inventors have found that it is effective to solve the above problems by laminating a polyurethane foam sheet on at least one surface of an aerogel-containing melamine foam sheet to form a composite heat insulating material, and have completed the present invention. Therefore, the present invention provides the following.

[0007] (1) A composite heat insulating material comprising an aerogel-containing melamine foam sheet containing melamine foam and aerogel, and a polyurethane foam sheet laminated on at least one surface of the aerogel-containing melamine foam sheet.

[0008] The composite heat insulating material of (1) comprises an aerogel-containing melamine foam sheet with high heat insulation and a polyurethane foam sheet with high strength, so it is excellent in heat insulation and strength.

[0009] (2) The composite heat insulating material according to (1), wherein the melamine foam has through-holes, and the polyurethane foam sheet has convex portions inserted into at least a part of the through-holes.

[0010] In the composite heat insulating material of (2), since the convex portions of the polyurethane foam sheet are inserted into the through-holes of the melamine foam sheet, the adhesion between the aerogel-containing melamine foam sheet and the polyurethane foam sheet is increased. Therefore, it is excellent in heat insulation and strength over a long period.

[0011] (3) The composite heat insulating material according to (1) or (2), wherein the ratio of the thickness of the polyurethane foam sheet to the thickness of the aerogel-containing melamine foam sheet is in the range of 1 / 5 or more and 5 or less.

[0012] In the composite heat insulating material of (3), since the ratio of the thickness of the aerogel-containing melamine foam sheet to the thickness of the polyurethane foam sheet is within the above range, the heat insulation and strength are improved in a well-balanced manner.

[0013] (4) The composite heat insulating material according to any one of (1) to (3), wherein the polyurethane foam sheet is an aerogel-containing polyurethane foam sheet containing aerogel.

[0014] In the composite heat insulating material of (4), since the polyurethane foam sheet contains aerogel, the heat insulation is further improved.

[0015] (5) Applying a polyurethane foam raw material liquid containing a polyisocyanate compound, a polyol, and a foaming agent onto at least one surface of an aerogel-containing melamine foam sheet, and reacting the polyurethane foam raw material liquid to produce a polyurethane foam sheet, a method for manufacturing a composite heat insulating material.

[0016] The method for manufacturing the composite heat insulating material in (5) reacts the polyurethane foam raw material liquid applied onto the surface of the aerogel-containing melamine foam sheet to produce a polyurethane foam sheet, so that the adhesion between the produced polyurethane foam sheet and the aerogel-containing melamine foam sheet is improved. Therefore, the composite heat insulating material obtained by the manufacturing method in (5) has excellent heat insulating properties and strength.

[0017] (6) A refrigerator comprising the composite heat insulating material according to any one of (1) to (3).

[0018] The refrigerator in (6) has high heat insulating properties because it is provided with the above-mentioned composite heat insulating material.

Advantages of the Invention

[0019] According to the present invention, it is possible to provide a heat insulating material excellent in heat insulating properties and strength, a method for manufacturing the same, and a refrigerator having high heat insulating properties using the heat insulating material.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0021] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0022] FIG. 1 is a cross-sectional view showing a composite heat insulating material according to an embodiment of the present invention.

[0023] As shown in FIG. 1, the composite heat insulating material 10 includes an aerogel-containing melamine foam sheet 11 and a polyurethane foam sheet 12 laminated on one surface of the aerogel-containing melamine foam sheet 11.

[0024] The aerogel-containing melamine foam sheet 11 includes a melamine foam sheet and an aerogel. The aerogel-containing melamine foam sheet 11 is a porous body having communication holes. The aerogel is, for example, silica aerogel. The average particle diameter of the aerogel may be, for example, in the range of 10 μm or more and 300 μm or less. The content of the aerogel in the aerogel-containing melamine foam sheet 11 may be, for example, in the range of 25% by mass or more and 35% by mass or less.

[0025] The polyurethane foam sheet 12 is a rigid polyurethane foam having closed cells (cells). A part of the polyurethane foam sheet 12 may be impregnated into the communication holes of the aerogel-containing melamine foam sheet 11. By impregnating a part of the polyurethane foam sheet 12 into the communication holes of the aerogel-containing melamine foam sheet 11, the adhesion between the aerogel-containing melamine foam sheet 11 and the polyurethane foam sheet 12 is increased. The polyurethane foam sheet 12 may be an aerogel-containing polyurethane foam sheet containing an aerogel.

[0026] The thicknesses of the aerogel-containing melamine foam sheet 11 and the polyurethane foam sheet 12 are not particularly limited. The thicknesses of the aerogel-containing melamine foam sheet 11 and the polyurethane foam sheet 12 may be, for example, in the range of 1 mm or more and 50 mm or less. The ratio of the thickness of the polyurethane foam sheet 12 to the thickness of the aerogel-containing melamine foam sheet 11 may be in the range of 1 / 5 or more and 5 or less.

[0027] The composite heat insulating material 10 can be produced, for example, by applying a polyurethane foam raw material liquid to the surface of the aerogel-containing melamine foam sheet 11 and reacting the polyurethane foam raw material liquid to produce the polyurethane foam sheet 12.

[0028] The method for producing the aerogel-containing melamine foam sheet 11 is not particularly limited. For example, it can be produced using the method described in Patent Document 1. A commercially available product can be used as the aerogel-containing melamine foam sheet 11.

[0029] The polyurethane foam raw material liquid contains a polyisocyanate compound, a polyol, and a foaming agent. The polyurethane formed by the reaction of the polyisocyanate compound and the polyol is foamed with the foaming agent to form a polyurethane foam. The polyurethane foam raw material liquid may contain a reaction catalyst. As the polyisocyanate compound, polyol, foaming agent, and reaction catalyst, known materials used in the production of polyurethane foam can be used. The polyurethane foam raw material liquid can be prepared by mixing a first liquid containing a polyol and a foaming agent and a second liquid containing a polyisocyanate. When forming an aerogel-containing polyurethane foam sheet, an aerogel may be added to the first liquid.

[0030] As a method of applying the polyurethane foam raw material liquid to the surface of the aerogel-containing melamine foam sheet 11, for example, a dip coating method, a spray coating method, a roll coating method, a doctor blade method, a gravure coating method, or a screen printing method can be used.

[0031] The composite heat insulating material 10 configured as described above includes the aerogel-containing melamine foam sheet 11 with high heat insulating properties and the polyurethane foam sheet 12 with high strength, so it is excellent in heat insulating properties and strength. In the composite heat insulating material 10 of the present embodiment, since a part of the polyurethane foam sheet 12 is impregnated in the communication holes of the aerogel-containing melamine foam sheet 11, the adhesion between the aerogel-containing melamine foam sheet 11 and the polyurethane foam sheet 12 is increased. For this reason, the heat insulating properties and strength are excellent over a long period of time.

[0032] In the composite heat insulating material 10 of the present embodiment, when the ratio of the thickness of the aerogel-containing melamine foam sheet 11 to the thickness of the polyurethane foam sheet 12 is within the above range, the heat insulating properties and strength are improved in a well-balanced manner. In the composite heat insulating material 10 of the present embodiment, when the polyurethane foam sheet 12 contains aerogel, the heat insulating properties are further improved.

[0033] Note that in the composite heat insulating material 10 of the present embodiment, the polyurethane foam sheet 12 is laminated on one surface of the aerogel-containing melamine foam sheet 11, but it is not limited thereto. For example, the polyurethane foam sheet 12 may be laminated on both surfaces of the aerogel-containing melamine foam sheet 11. Further, the entire aerogel-containing melamine foam sheet 11 may be covered with the polyurethane foam sheet 12.

[0034] The manufacturing method of the composite heat insulating material 10 of the present embodiment reacts the polyurethane foam raw material liquid applied to the surface of the aerogel-containing melamine foam sheet 11 to generate a polyurethane foam sheet 12. Therefore, a part of the polyurethane foam sheet 12 is impregnated into the communication holes of the aerogel-containing melamine foam sheet 11. For this reason, the adhesion between the polyurethane foam sheet 12 and the aerogel-containing melamine foam sheet 11 is improved. Therefore, the composite heat insulating material 10 obtained by the manufacturing method of the present embodiment has excellent heat insulation properties and strength.

[0035] FIG. 2 is a front view showing a refrigerator according to an embodiment of the present invention. FIG. 3 is a sectional view taken along line III-III of FIG. 2.

[0036] As shown in FIGS. 2 and 3, the refrigerator 20 of the present embodiment has a structure divided into three stages: an upper stage portion 21, a middle stage portion 22, and a lower stage portion 23. The refrigerator 20 includes a heat insulating box body 30 with an open front and a door for opening and closing the opening of the heat insulating box body. The upper stage portion 21 can be opened and closed by an upper right heat insulating door 41a and an upper left heat insulating door 41b, the middle stage portion 22 can be opened and closed by a middle heat insulating door 42, and the lower stage portion 23 can be opened and closed by a lower heat insulating door 43. The upper right heat insulating door 41a is a rotary door that can rotate about the right side end surface, and the upper left heat insulating door 41b can rotate about the left end portion. The middle heat insulating door 42 and the lower heat insulating door 43 are each a drawer-type door provided with a storage container 44.

[0037] As shown in FIG. 3, the heat-insulating box body 30 includes a composite heat-insulating material 10 and a frame 31 that covers the outside of the composite heat-insulating material 10. The composite heat-insulating material 10 is disposed inside the frame 31. The composite heat-insulating material 10 is arranged such that the side of the aerogel-containing melamine foam sheet 11 is in contact with the frame 31. The composite heat-insulating material 10 is covered with a polyurethane foam 13. As the polyurethane foam 13, a known polyurethane foam used in conventional refrigerators can be used. The heat-insulating box body 30 has a first heat-insulating plate 32 that insulates the upper stage portion 21 and the middle stage portion 22, and a second heat-insulating plate 33 that insulates the middle stage portion 22 and the lower stage portion 23. The first heat-insulating plate 32 and the second heat-insulating plate 33 are formed of the polyurethane foam 13.

[0038] As shown in FIG. 3, a machine room 51 is provided on the back side of the lower stage portion 23 of the refrigerator 20. A compressor 52 is housed in the machine room 51. A cooling chamber 53 is partitioned and formed on the back side of the middle stage portion 22, and an evaporator 54 is housed in the cooling chamber 53. The evaporator 54 and the compressor 52 are connected via an expansion means and a condenser (not shown) and a refrigerant pipe to form a vapor compression refrigeration cycle.

[0039] A part of the cold air inside the cooling chamber 53 cooled by the evaporator 54 is sent to the middle section 22 through the blower 55 and the cold air pipe 56 to cool the middle section 22. The cold air that has cooled the middle section 22 flows into the cooling chamber 53 and is cooled again by the evaporator 54. The remaining cold air is sent to the upper section 21 to cool the upper section 21. The cold air that has cooled the upper section 21 is sent to the lower section 23 through a cold air pipe (not shown), cools the lower section 23, and then is sent to the cooling chamber 53 through a cold air pipe (not shown) and is cooled again by the evaporator 54. A damper (not shown) is arranged in the cold air pipe. The control device (not shown) of the refrigerator 20 controls the opening and closing of the damper based on the temperature inside the refrigerator measured by an in-refrigerator temperature sensor (not shown). Thereby, the flow rate of the cold air is adjusted to keep the temperature inside the refrigerator constant. In this way, the upper section 21, the middle section 22, and the lower section 23 are cooled to a predetermined temperature range. The arrows in Fig. 3 indicate the flow of the cold air. Further, below the evaporator 54, a defrosting heater 57 for melting the frost on the evaporator 54 is provided.

[0040] In the refrigerator 20 of the present embodiment configured as described above, since the above-described composite heat insulating material 10 is arranged in the heat insulating box body 30, the heat insulation performance with the outside is high.

[0041] As described above, the embodiments of the present invention have been described in detail, but the present invention is not limited to the above-described embodiments. For example, in the composite heat insulating material 10 of the present embodiment, the aerogel-containing melamine foam sheet 11 and the polyurethane foam sheet 12 are in direct contact, but the structure of the composite heat insulating material 10 is not limited thereto. The aerogel-containing melamine foam sheet 11 and the polyurethane foam sheet 12 may be fixed by an adhesive. Further, in the refrigerator 20 of the present embodiment, the composite heat insulating material 10 is arranged such that the aerogel-containing melamine foam sheet 11 side contacts the frame 31, but the composite heat insulating material 10 may be arranged such that the polyurethane foam sheet 12 side contacts the frame 31.

[0042] In the refrigerator of the present embodiment, the composite heat insulating material 10 is disposed inside the frame 31 and is not disposed on the first heat insulating plate 32 and the second heat insulating plate 33, but the arrangement position of the composite heat insulating material 10 is not limited thereto. The composite heat insulating material 10 may be disposed on the first heat insulating plate 32 and the second heat insulating plate 33.

Example

[0043] [Example 1] A commercially available aerogel-containing polymelamine foam sheet was prepared. This aerogel-containing polymelamine foam sheet has communicating pores, a thickness of 20.0 mm, an average particle diameter of silica aerogel of 100 μm, and a silica aerogel content of 30% by mass. Also, a first liquid containing a polyol-containing liquid (manufactured by Sumika Covestro Urethane Co., Ltd.) and a foaming agent, and a second liquid containing a polyisocyanate were prepared. The first liquid and the second liquid were mixed to prepare a polyurethane foam raw material liquid.

[0044] The aerogel-containing polymelamine foam sheet was placed in a space tray with a heat insulating thickness of 50 mm. Next, the polyurethane foam raw material liquid was poured onto the surface of the aerogel-containing polymelamine foam sheet so that the thickness of the polyurethane foam sheet to be formed was 5.0 mm, and the polyurethane foam raw material liquid was reacted to form a polyurethane foam sheet. After the reaction was completed, the laminated sheet was taken out of the tray. Thus, a composite heat insulating material in which a 20.0-mm-thick aerogel-containing polymelamine foam sheet (first sheet) and a 5.0-mm-thick polyurethane foam sheet (second sheet) were laminated was obtained.

[0045] [Example 2] A composite heat insulating material was obtained in the same manner as in Example 1, except that the thickness of the aerogel-containing polymelamine foam sheet was 12.5 mm and the thickness of the polyurethane foam sheet was 12.5 mm.

[0046] [Example 3] A composite heat insulating material was obtained in the same manner as in Example 1, except that the thickness of the aerogel-containing polymelamine foam sheet was set to 5.0 mm and the thickness of the polyurethane foam sheet was set to 20.0 mm.

[0047] [Example 4] Aerogel (average particle diameter: 100 μm) was added to the first liquid, and an aerogel-containing polyurethane foam sheet having an aerogel content of 30% by mass was produced instead of the polyurethane foam sheet. A composite heat insulating material was obtained in the same manner as in Example 1, except that the thickness of the aerogel-containing polymelamine foam sheet was set to 12.5 mm and the thickness of the aerogel-containing polyurethane foam sheet was set to 12.5 mm.

[0048] [Comparative Example 1] An insulating material of a single layer of polyurethane foam sheet with a thickness of 25.0 mm was obtained using a polyurethane foam raw material liquid without using an aerogel-containing polymelamine foam sheet.

[0049] [Comparative Example 2] A commercially available polymelamine foam sheet with a thickness of 25.0 mm was prepared as an insulating material.

[0050] [Comparative Example 3] An aerogel-containing polymelamine foam sheet identical to the aerogel-containing polymelamine foam sheet prepared in Example 1 was prepared as an insulating material, except that the thickness was 25.0 mm.

[0051] [Comparative Example 4] A composite heat insulating material was obtained in the same manner as in Example 1, except that a commercially available polymelamine foam sheet with a thickness of 12.5 mm was used instead of the aerogel-containing polymelamine foam sheet and the thickness of the polyurethane foam sheet was set to 12.5 mm.

[0052] [Evaluation] For the heat insulating materials obtained in each example and comparative example, the density, thermal conductivity, and compressive strength at 10% deformation were measured by the following methods. The results are shown in Table 1.

[0053] (Density) The obtained heat insulating material was cut out to be square in plan view to obtain test pieces. The size of the obtained test pieces was measured with calipers to calculate the volume of the test pieces, and the weight of the test pieces was measured with an analytical balance. The density was determined by dividing the weight of the test pieces by the volume.

[0054] (Thermal conductivity) The measurement was carried out under the condition of the average temperature of the test body being 24°C by a method conforming to JIS A 1412-2:1999 "Methods of measurement of thermal resistance and thermal conductivity of thermal insulating materials - Part 2: Heat flow meter method (HFM method)".

[0055] (Compressive strength at 10% deformation) The compressive strength value at 10% deformation was measured by a method conforming to JIS K 7220:2006 "Rigid cellular plastics - Determination of compressive properties".

[0056] [Table 1]

[0057] From the results in Table 1, it can be seen that the composite heat insulating materials obtained in Examples 1 to 4 in which the aerogel-containing polymelamine foam sheet (the first sheet) and the polyurethane foam sheet (the second sheet) are laminated have a well-balanced improvement in heat insulation and strength as compared with the heat insulating materials obtained in Comparative Examples 1 to 4. On the other hand, in Comparative Example 1 of a single polyurethane foam sheet, the strength is high but the heat insulation is slightly low. In Comparative Example 2 of a single polymelamine foam sheet, both the heat insulation and the strength are low. In Comparative Example 3 of a single aerogel-containing polymelamine foam sheet, the heat insulation is high but the strength is low. In Comparative Example 4 in which the polymelamine foam sheet (the first sheet) and the polyurethane foam sheet (the second sheet) are laminated, both the heat insulation and the strength are low.

Description of reference numerals

[0058] 10 Composite heat insulating material 11 Aerogel-containing melamine foam sheet 12 Polyurethane foam sheet 13 Polyurethane foam 20 Refrigerator 21 Upper part 22 Middle part 23 Lower part 30 Heat-insulating box body 31 Frame 32 First heat-insulating plate 33 Second heat-insulating plate 41a Upper right heat-insulating door 41b Upper left heat-insulating door 42 Middle heat-insulating door 43 Lower heat-insulating door 44 Storage container 51 Machine room 52 Compressor 53 Cooling chamber 54 Evaporator 54 Re-evaporator 55 Blower 56 Cold air pipe 57 Defrosting heater

Claims

1. A melamine foam-containing aerogel foam sheet containing a melamine foam and an aerogel, and A polyurethane foam sheet laminated on at least one surface of the melamine foam-containing aerogel foam sheet, a composite heat insulating material.

2. The composite heat insulating material according to Claim 1, wherein the melamine foam-containing aerogel foam sheet has through-holes.

3. The composite heat insulating material according to Claim 1 or 2, wherein the ratio of the thickness of the polyurethane foam sheet to the thickness of the melamine foam-containing aerogel foam sheet is in the range of 1 / 5 or more and 5 or less.

4. The composite heat insulating material according to Claim 1 or 2, wherein the polyurethane foam sheet is an aerogel-containing polyurethane foam sheet containing an aerogel.

5. A method for producing a composite heat insulating material, wherein a polyurethane foam raw material liquid containing a polyisocyanate compound, a polyol and a foaming agent is applied to at least one surface of a melamine foam-containing aerogel foam sheet containing a melamine foam and an aerogel, and the polyurethane foam raw material liquid is reacted to produce a polyurethane foam sheet.

6. A refrigerator comprising the composite heat insulating material according to Claim 1 or 2.

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