Heat insulating material and refrigerator, refrigerator-freezer, or freezer using the same

Abstract

To provide a thermal insulation material that comprises a polyurethane foam having high thermal insulation performance and containing fine bubbles.SOLUTION: A thermal insulation material comprises a polyurethane foam that contains 0.2-3% of a hydrophilic aerogel. The polyurethane foam comprises a mixed product of a polyol mixture of an amine polyol, a polyester polyol, and an aliphatic amine compound as a catalyst, a polyisocyanate of diphenylmethane diisocyanate, and a foaming agent of cyclopentane, and the hydrophilic aerogel is a silica aerogel.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a heat insulating material including a polyurethane foam and a refrigerator, a refrigerator-freezer, or a freezer using the same. [Background technology]

[0002] Rigid polyurethane foam, a type of foamed resin, is widely used as insulation for refrigerators, refrigerator-freezers, and freezers. There is a demand for the development of next-generation, high-performance insulation materials that improve on this polyurethane foam.

[0003] The time it takes for polyol and polyisocyanate to become a resin is called gel time. Polyurethane foam can be made finer by making it finer. Normally, shortening the gel time shortens the time it takes for polyurethane foam to expand, and the polyurethane foam's bubbles become finer.

[0004] However, if the gel time is shortened, the polyurethane foam will foam before it has reached the entire area of ​​the product to be filled, resulting in unfilled areas.

[0005] Furthermore, Patent Document 1 describes a high-performance thermal insulating material comprising a polymer matrix, aerogel particles, and expanded microspheres, wherein the aerogel particles are present in an amount of 30% by mass or more, the polymer matrix is ​​present in an amount of 20% by mass or more, and the expanded microspheres are present in an amount of 0.5 to 15% by mass, where the mass percentages are based on the total mass of the polymer matrix, aerogel particles, and expanded microspheres, and the thermal conductivity of the thermal insulating material is less than 40 mW / mK under atmospheric conditions. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2020-515685 Summary of the Invention [Problem to be solved by the invention]

[0007] As such, it was not possible to make the polyurethane foam cells finer and eliminate unfilled areas in the product. Furthermore, none of the examples in Patent Document 1 use polyurethane foam in the polymer matrix. Furthermore, the heat insulating material produced in Patent Document 1 uses a large amount of aerogel, making it expensive.

[0008] Therefore, an object of the present invention is to provide a thermal insulation material that suppresses bubble expansion, minimizes the size of the polyurethane foam bubbles, extends the gel time, and eliminates unfilled areas. Another object of the present invention is to provide a thermal insulation material using polyurethane foam with an optimized aerogel content and improved thermal insulation performance. [Means for solving the problem]

[0009] The present invention solves one of the above problems by mixing a hydrophilic aerogel with high heat insulating properties into the raw material of polyurethane foam to increase the viscosity of the material.The present invention also solves one of the above problems by providing a polyurethane foam with an optimized hydrophilic aerogel content.

[0010] That is, the heat insulating material of the present invention is It is characterized by comprising polyurethane foam containing 0.2% to 3% hydrophilic aerogel.

[0011] The thermal insulation material of the present invention suppresses bubble expansion by mixing a hydrophilic aerogel with high thermal insulation properties into the raw material of polyurethane foam to increase the viscosity of the material. Furthermore, the thermal insulation material of the present invention can extend the gel time and eliminate unfilled areas in the product. Furthermore, the thermal insulation material of the present invention uses polyurethane foam with an optimized content of hydrophilic aerogel, thereby improving thermal insulation performance.

[0012] The present invention also provides The polyurethane foam is characterized in that the average cell diameter is 142 μm or less.

[0013] The present invention can make the average cell diameter (cell size) smaller than that of conventional urethane foams.

[0014] Further, the heat insulating material of the present invention is It is characterized by having polyurethane foam containing 0.2% to 0.5% hydrophilic aerogel.

[0015] The heat insulating material of the present invention can further improve its heat insulating performance by adjusting the content of the hydrophilic aerogel relative to the polyurethane foam.

[0016] The present invention also provides The polyurethane foam is characterized in that the average cell diameter is 137 μm or less.

[0017] In the heat insulating material of the present invention, the average cell diameter can be further reduced by adjusting the content of the hydrophilic aerogel relative to the polyurethane foam.

[0018] The present invention also provides The polyurethane foam is a polyol mixture of an amine polyol, a polyester polyol, and an aliphatic amine compound as a catalyst; a polyisocyanate of diphenylmethane diisocyanate; obtained from a mixture of cyclopentane and a blowing agent, The hydrophilic aerogel is characterized in that it is a silica aerogel.

[0019] The polyurethane foam of the present invention is obtained from a mixture of a polyol mixture of an amine polyol, a polyester polyol, and an aliphatic amine compound as a catalyst, a polyisocyanate of diphenylmethane diisocyanate, and a blowing agent of cyclopentane, and the hydrophilic aerogel of the present invention is a silica aerogel.

[0020] Further, the refrigerator, refrigerator-freezer, or freezer of the present invention comprises: The heat insulating material is characterized in that the polyurethane foam is a rigid polyurethane foam.

[0021] The refrigerator, refrigerator-freezer or freezer of the present invention can have improved heat insulating performance by using the heat insulating material in which the polyurethane foam is a rigid polyurethane foam. [Effects of the Invention]

[0022] According to the present invention, a thermal insulating material with improved thermal insulation performance can be provided. According to the present invention, a thermal insulating material with an average cell diameter smaller than that of conventional urethane foam can be provided. According to the present invention, by adjusting the content of hydrophilic aerogel relative to polyurethane foam, a thermal insulating material with further improved thermal insulation performance can be provided. According to the present invention, by adjusting the content of hydrophilic aerogel relative to polyurethane foam, a thermal insulating material with an even smaller average cell diameter can be provided.

[0023] The present invention also provides a heat insulating material in which the polyurethane foam is obtained from a mixture of a polyol mixture of an amine polyol, a polyester polyol, and an aliphatic amine compound as a catalyst, a polyisocyanate of diphenylmethane diisocyanate, and a blowing agent of cyclopentane, and the hydrophilic aerogel is silica aerogel.The present invention also provides a refrigerator, refrigerator-freezer, or freezer having improved heat insulating performance using the heat insulating material in which the polyurethane foam is a rigid polyurethane foam. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a photograph showing the cell diameter measurement of the polyurethane foam of Example 2. [Figure 2] 1 is a photograph showing the cell diameter measurement of the polyurethane foam of Example 4. [Figure 3] 1 is a photograph showing the cell diameter measurement of the polyurethane foam of Comparative Example 2. [Figure 4]1 is a photograph showing cell diameter measurement of a conventional polyurethane foam. DETAILED DESCRIPTION OF THE INVENTION

[0025] (Embodiment) A polyurethane foam according to an embodiment of the present invention will be described.

[0026] The polyurethane foam according to the present invention is obtained by reacting a polyol mixture of a polyol compound and a catalyst with a polyisocyanate compound in the presence of a foaming agent and a hydrophilic aerogel. The structure of the polyurethane foam after the reaction is complex and cannot be generally identified. Therefore, the polyurethane foam is identified by identifying the raw materials.

[0027] The polyol compound of the polyol mixture according to an embodiment of the present invention includes an amine-based polyol, which includes one or more of triethanolamine, ethylenediamine, aromatic diamine, and diethylenetriamine.

[0028] The polyol compound of the polyol mixture according to the embodiment of the present invention includes a polyester polyol. The polyester polyol is produced by dehydration condensation of several carboxylic acids and polyhydric alcohols. Examples of the carboxylic acid include adipic acid and phthalic acid, and examples of the polyhydric alcohol include ethylene glycol, 1,4-butanediol, and 1,6-hexanediol. Rigid polyurethane foams are primarily made using phthalic acid-based polyester polyols.

[0029] The catalyst for the polyol mixture according to the embodiment of the present invention is used to control the synthesis reaction of polyurethane foam. The catalyst for the polyol mixture according to the embodiment of the present invention includes an aliphatic amine. The aliphatic amine can be one or more of methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, triethanolamine, N,N-diisopropylethylamine, tetramethylethylenediamine, hexamethylenediamine, spermidine, spermine, amantadine, tetramethylhexanediamine, and pentamethyldiethylenetriamine.

[0030] The polyol mixture according to the embodiment of the present invention is preferably used in an amount of 100 parts by weight.

[0031] As the isocyanate compound of the polyisocyanate according to the embodiment of the present invention, one or more of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and xylene diisocyanate can be used.

[0032] In the embodiment of the present invention, diphenylmethane diisocyanate is preferably used as the isocyanate compound, and the polyisocyanate according to the embodiment of the present invention is preferably used in an amount of 124 parts by weight.

[0033] The polyurethane foam according to the embodiment of the present invention is foamed using a blowing agent. The blowing agent according to the embodiment of the present invention can be one or more of cyclopentane, trichlorofluoromethane, 1,1-dichloro-1-fluoromethane, 1,1,1,3,3-pentafluoropropane, 1,1,1,3,3-pentafluorobutane, and carbon dioxide. The blowing agent according to the embodiment of the present invention is preferably cyclopentane. Furthermore, the blowing agent according to the embodiment of the present invention is preferably used in an amount of 14 parts by weight.

[0034] When 100 parts by weight of a polyol mixture of a polyol compound and a catalyst is reacted with 124 parts by weight of a polyisocyanate of an isocyanate compound in the presence of 14 parts by weight of a blowing agent, preferably 100 parts by weight of a polyurethane foam according to an embodiment of the present invention is formed.

[0035] The foaming of the polyurethane foam according to the embodiment of the present invention is controlled by a hydrophilic aerogel, which may be silica aerogel, carbon aerogel, metal aerogel, or polymer aerogel.

[0036] The hydrophilic aerogel according to the embodiment of the present invention preferably uses silica aerogel. Hydrophilic silica aerogel has high hydrophilicity due to hydroxyl groups on its surface. The hydrophilic aerogel according to the embodiment of the present invention is preferably in the form of particles with a particle size of 200 μm to 400 μm. The hydrophilic aerogel according to the embodiment of the present invention is preferably used in an amount of 0.2 to 3 parts by weight.

[0037] According to the above embodiment, the polyurethane foam raw material is mixed with a hydrophilic aerogel having high thermal insulation properties to increase the viscosity of the material, thereby suppressing bubble expansion. Furthermore, according to the above embodiment, the gel time can be extended, eliminating unfilled portions in the product. Furthermore, according to the above embodiment, the polyurethane foam is used with an optimized content of hydrophilic aerogel, thereby improving thermal insulation performance. [Example]

[0038] In this example, polyurethane foams according to Examples 1 to 4, Comparative Examples 1 and 2, and a conventional example were produced using the raw materials listed in Table 1. The polyurethane foams of Examples 1 to 4 were obtained by a production method involving a step of reacting a polyol mixture with a polyisocyanate in the presence of a blowing agent and a hydrophilic aerogel. The polyurethane foams of Comparative Examples 1 and 2 were obtained by a production method involving a step of reacting a polyol mixture with a polyisocyanate in the presence of a blowing agent and a hydrophobic aerogel. The polyurethane foam of the conventional example was obtained by a production method involving a step of reacting a polyol mixture with a polyisocyanate in the presence of a blowing agent.

[0039] [Table 1]

[0040] The polyol mixture and aerogel are as follows: Polyol: Sumika Covestro Urethane Co., Ltd. Aerogel: Made by Guangdong Allison High-Tech Co., Ltd.

[0041] The thermal conductivity was measured using FOX200 manufactured by Eiko Seiki Co., Ltd.

[0042] In each polyurethane foam, 100 parts by weight of the polyol mixture, 14 parts by weight of the blowing agent, and 124 parts by weight of the polyisocyanate were reacted to form 100 parts by weight of polyurethane foam.

[0043] The polyurethane foam of Example 1 contains 0.2 parts by weight of hydrophilic aerogel, i.e., 0.2% hydrophilic aerogel relative to the polyurethane foam. The polyurethane foam of Example 2 contains 0.5 parts by weight of hydrophilic aerogel, i.e., 0.5% hydrophilic aerogel relative to the polyurethane foam. The polyurethane foam of Example 3 contains 1.0 parts by weight of hydrophilic aerogel, i.e., 1.0% hydrophilic aerogel relative to the polyurethane foam. The polyurethane foam of Example 4 contains 3.0 parts by weight of hydrophilic aerogel, i.e., 3.0% hydrophilic aerogel relative to the polyurethane foam. Examples 1 to 4 have the same other components but vary in the amount of hydrophilic aerogel.

[0044] On the other hand, the polyurethane foam of Comparative Example 1 contains 1.0 part by weight of hydrophobic aerogel, i.e., 1.0% of the hydrophobic aerogel relative to the polyurethane foam, and the polyurethane foam of Comparative Example 2 contains 3.0 parts by weight of hydrophobic aerogel, i.e., 3.0% of the hydrophobic aerogel relative to the polyurethane foam. Comparative Examples 1 and 2 differ from the Examples in that they contain hydrophobic aerogel instead of hydrophilic aerogel. The polyurethane foam of the conventional example does not contain aerogel.

[0045] Examples 1 to 4, which contained a hydrophilic aerogel content of 0.2% to 3%, achieved a thermal conductivity of 20.5 mW / m·K or less. This was lower than the thermal conductivity of the conventional polyurethane foam, 20.9 mW / m·K. Therefore, Examples 1 to 4 had higher thermal insulation performance than the conventional polyurethane foam. In particular, Examples 1 and 2 achieved an even lower thermal conductivity of 20.3 mW / m·K. Therefore, by adjusting the hydrophilic aerogel content to 0.2% to 0.5% without changing the other components, the thermal insulation performance was further improved.

[0046] In contrast, Comparative Example 1 had a thermal conductivity of 21.0 mW / m·k. Comparative Example 2 had a thermal conductivity of 21.6 mW / m·k. Both Comparative Examples 1 and 2 were higher than the thermal conductivity of conventional polyurethane foam, which was 20.9 mW / m·K. Therefore, it was found that the inclusion of hydrophobic aerogel instead of hydrophilic aerogel resulted in poorer heat insulation performance.

[0047] Furthermore, Examples 1 to 4 had a lower foam density than the conventional polyurethane foam, making the polyurethane foam lighter. Furthermore, Examples 1 to 4 were comparable to the conventional polyurethane foam in terms of low-temperature dimensional stability (-30°C x 48h (%)) and high-temperature dimensional stability (70°C x 48h (%)). Furthermore, Examples 1 to 4 also had a compressive strength of 1.2 to 1.5 kgf cm. 2 ) and is comparable to conventional examples.

[0048] Furthermore, in Examples 1 to 4, the foam state was free of cell roughness.

[0049] Fig. 1 is a photograph showing cell diameter measurement of the polyurethane foam of Example 2. Fig. 2 is a photograph showing cell diameter measurement of the polyurethane foam of Example 4. Fig. 3 is a photograph showing cell diameter measurement of the polyurethane foam of Comparative Example 2. Fig. 4 is a photograph showing cell diameter measurement of a conventional polyurethane foam. The cell diameters (cell size) of polyurethane foams according to embodiments of the present invention will be described with reference to Figs. 1 to 4.

[0050] Referring to Figure 1, the average cell diameter of the polyurethane foam of Example 2 was approximately 137 μm. Referring to Figure 2, the average cell diameter of the polyurethane foam of Example 4 was approximately 142 μm. This shows that the average cell diameter decreases when the hydrophilic aerogel content of the polyurethane foam is reduced from 3% to 0.5%.

[0051] Referring to Figure 3, the average cell diameter of the polyurethane foam of Comparative Example 2 was 167 µm. Referring to Figure 4, the average cell diameter of the polyurethane foam of the conventional example was 197 µm. Figures 1 to 4 show that the polyurethane foam containing hydrophobic aerogel and the conventional polyurethane foam both had larger average cell diameters than the polyurethane foam containing hydrophilic aerogel.

[0052] Therefore, in Examples 1 to 4, the average cell diameter was reduced, i.e., the bubbles were made finer, compared to Comparative Examples 1 and 2 and the conventional example. Furthermore, in Examples 1 to 4, the average cell diameter could be further reduced by adjusting the content of hydrophilic aerogel.

[0053] Such rigid polyurethane foam insulation can be filled into products without leaving any unfilled areas or cell roughness, and is light and has little temperature deformation, so it can be used in refrigerators, freezers, or refrigerator-freezers.

[0054] According to the present invention, a thermal insulating material with improved thermal insulation performance can be provided. According to the present invention, a thermal insulating material with an average cell diameter smaller than that of conventional urethane foam can be provided. According to the present invention, by adjusting the content of hydrophilic aerogel relative to polyurethane foam, a thermal insulating material with further improved thermal insulation performance can be provided. According to the present invention, by adjusting the content of hydrophilic aerogel relative to polyurethane foam, a thermal insulating material with an even smaller average cell diameter can be provided.

[0055] The present invention also provides a heat insulating material in which the polyurethane foam is obtained from a mixture of a polyol mixture of an amine polyol, a polyester polyol, and an aliphatic amine compound as a catalyst, a polyisocyanate of diphenylmethane diisocyanate, and a blowing agent of cyclopentane, and the hydrophilic aerogel is silica aerogel.The present invention also provides a refrigerator, refrigerator-freezer, or freezer that uses a heat insulating material in which the polyurethane foam is a rigid polyurethane foam. [Industrial Applicability]

[0056] The polyurethane foam of the present invention has low thermal conductivity and can be used as a heat insulating material for refrigerators, freezers, and refrigerator-freezers. The polyurethane foam of the present invention can also be used as a building material for sandwich panels and boards, a cold insulation pipe, etc.

Claims

1. 1. An insulating material for use in a refrigerator, refrigerator-freezer, or freezer, comprising rigid polyurethane foam containing 0.2% to 0.5% hydrophilic aerogel.

2. The heat insulating material according to claim 1, wherein the polyurethane foam has an average cell diameter of 137 μm or less.

3. The polyurethane foam is a polyol mixture of an amine polyol, a polyester polyol, and an aliphatic amine compound as a catalyst; a polyisocyanate of diphenylmethane diisocyanate; obtained from a mixture of cyclopentane and a blowing agent, 3. The heat insulating material according to claim 1, wherein the hydrophilic aerogel is silica aerogel.

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