JP2007056922A - Vacuum heat insulating material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently produce a high quality vacuum heat insulating material having an excellent heat insulating performance for a long period of time without causing problems of sealing strength, foreign matter adhesion sealing property and pin-hole resistance even in the case that a sealant film is thin. <P>SOLUTION: In the vacuum heat insulating material 11 wherein a core material 12 is covered by an outer covering material 13 consisting of a laminated film having a sealant film of which thickness is ≤40 μm and ≥20 μm as an innermost layer and inside of the outer covering material 13 is decompressed and tightly sealed, density of the sealant film is ≤0.945g/cm<SP>3</SP>and ≥0.920 g/cm<SP>3</SP>and total thickness of the laminated film is ≥70 μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vacuum heat insulating material that includes a core material and a jacket material, the core material is covered with the jacket material, and the inside is sealed under reduced pressure.

  In recent years, various efforts have been made to suppress global warming, and one of them is energy saving measures by improving the performance of heat insulating materials. One means of energy saving measures using a heat insulating material is application of a vacuum heat insulating material having excellent heat insulating performance.

  Vacuum insulation is a glass fiber, foam, or powder core material covered with a gas barrier plastic laminated film and sealed inside under reduced pressure, and is used as a heat insulation material in a wide range of fields due to its excellent heat insulation performance. Has been.

  Such a vacuum heat insulating material keeps the inside at a high degree of vacuum, thereby reducing heat conduction due to gas components and improving heat insulating performance. Therefore, in order to maintain the heat insulating performance over a long period of time, it is necessary to maintain the internal vacuum, and it is necessary to apply a plastic laminated film material having a high gas barrier property and to optimize the laminated film configuration.

  In particular, when a metal foil having a predetermined thickness or more is laminated on a plastic laminated film, the gas intrusion from the outside is dominated by the intrusion from the side surface of the end portion of the seal layer. As an example of improving this, there is a vacuum heat insulating material having a hollow portion formed by sealing the end of a laminated film having at least one resin-containing layer (A layer) having a gas barrier property and a sealant layer. Thus, it has been proposed that the seal part is preferably a vacuum heat insulating material satisfying H / d> 20 when the sealant layer thickness is d (mm) and the seal width is H (mm) (for example, Patent Document 1).

  In the above prior art, when H / d is 20 or less, gas permeation from the seal portion increases. Therefore, the larger H / d is, from the viewpoint of gas barrier properties, preferably 1 × 10 2 or more, more preferably 1 × 10 3 or more. Further preference has been shown.

  Specifically, from the viewpoint of gas barrier properties, d is preferably 0.2 mm or less, more preferably 0.05 mm or less, and particularly preferably 0.04 mm or less. On the other hand, it has been proposed that H is preferably 10 mm or more and more preferably 20 mm or more from the viewpoint of gas barrier properties.

With the above configuration, the heat insulating performance is excellent and heat insulating properties can be maintained over a long period of time as compared with the conventional one.
Japanese Patent Laid-Open No. 11-257578

  However, in the above conventional configuration, the smaller the thickness d of the sealant layer, the better the gas barrier property. However, in reality, when the thickness d of the sealant layer is reduced, the heat sealing property, particularly Since the sealing property of foreign substances is deteriorated, there is a tendency that the problem of the vacuum heat insulating material leaking due to heat sealing failure increases.

  In addition, because the heat seal strength and the absolute strength of the sealant film are insufficient, the rate of occurrence of problems such as bag breakage and pinholes in laminated films increases dramatically, making it difficult to stably produce high-quality vacuum insulation materials. Met.

  The present invention solves the above-mentioned conventional problems, and aims to provide a high-quality vacuum heat insulating material excellent in heat insulating performance over a long period of time by ensuring excellent gas barrier properties and excellent productivity. To do.

In order to solve the above-mentioned conventional problems, the vacuum heat insulating material of the present invention covers a core material with an outer cover material made of a laminated film having a sealant film having a thickness of at least 40 μm or less and 20 μm or more as an innermost layer, in vacuum insulation material comprising the interior of wood by vacuum sealing, the density of the sealant film is at 0.945 g / cm ³ or less 0.920 g / cm ³ or more, and the total thickness of the configuration of the above 70μm of the laminated film It consists of

  In general, the physical properties of a sealant film vary greatly depending on the density difference. For example, when the density is increased by using a polyethylene film, the rigidity, hardness, melting point, heat distortion temperature, gas impermeability, and the like are improved. On the other hand, when the density is lowered, impact properties, transparency, and heat sealing properties are improved.

Such a physical property difference is due to the molecular structure, and the difference in molecular structure due to the starting material (monomer), molecular weight, and the presence or absence of copolymerization, etc. appears as a difference in film density and crystallinity. . In particular, the density of the sealant film is if 0.945 g / cm ³ or less 0.920 g / cm ³ or more ranges, sufficient heat-seal strength even when the thickness of the sealant film is lowered has been found to be ensured.

Therefore, even in the case of a vacuum heat insulating material to which a jacket material made of a laminated film having a sealant film having a thickness of 40 μm or less and 20 μm or more is applied, the density of the sealant film is 0.945 g / cm ³ or less and 0.920 g / cm ^3. If it is the above range, the high quality vacuum heat insulating material which has sufficient heat-sealing intensity | strength and the outstanding pinhole resistance can be provided, ensuring the outstanding gas-barrier property.

  The vacuum heat insulating material of the present invention is provided with a covering material made of a laminated film having sufficient heat seal strength and excellent pinhole resistance while ensuring excellent gas barrier properties as a covering material of the vacuum heat insulating material. Therefore, a high-quality vacuum heat insulating material having excellent heat insulating performance over a long period of time can be produced with high efficiency.

The invention of a vacuum heat insulating material according to claim 1 of the present invention is characterized in that the core material is covered with a jacket material made of a laminated film having at least a sealant film having a thickness of 40 μm or less and 20 μm or more as an innermost layer, in the vacuum heat insulating material formed through vacuum sealed, the density of the sealant film as a 0.945 g / cm ³ or less 0.920 g / cm ³ or more, and is obtained by the total thickness of the multilayer film as above 70 [mu] m.

  In general, the physical properties of a sealant film vary greatly depending on the density difference. Such a physical property difference is due to the molecular structure, and the difference in molecular structure due to the starting material (monomer), molecular weight, and the presence or absence of copolymerization, etc. appears as a difference in film density and crystallinity. .

In particular, if the range density of 0.945 g / cm ³ or less 0.920 g / cm ³ or more sealant film, the molecular structure of sealant film is optimized, even when the thickness of the sealant film is decreased, sufficient It was found that heat seal strength can be secured.

However, the density of the sealant film is even 0.945 g / cm ³ or less 0.920 g / cm ³ or more ranges, the thickness of the sealant film, the total thickness of the laminated film at 20μm or more only in the case of more than 70 [mu] m, High quality vacuum insulation can be secured. This is considered to be the minimum thickness necessary to ensure the absolute strength of the film.

  From the above results, all the elements of fracture strength related to heat seal strength, such as interface fracture at the heat seal layer interface, heat seal layer cohesive failure, and cohesive failure at the adherend layer, are improved, so heat seal quality Is an improvement.

  The invention of the vacuum heat insulating material according to claim 2 is the one in which the crystallinity of the sealant film in the invention according to claim 1 is 85% or less and 65% or more.

In the present invention, similar to the operation of the first aspect, the film physical properties greatly differ depending on the crystallinity of the sealant film. Such physical property difference is due to its molecular structure, and the difference in molecular structure due to its starting material (monomer), molecular weight, and the presence or absence of copolymerization appears as a difference in film crystallinity. The higher the degree of crystallinity, the better the gas barrier properties of the sealant film. However, as a detrimental effect, the heat seal strength is lowered, and the impact strength of the sealant film is lowered. Therefore, it has been found that the film strength cannot be ensured for the jacket material of the vacuum heat insulating material.

  Therefore, the detailed mechanism is unknown, but only when the crystallinity of the sealant film is 85% or less and 65% or more, the molecular structure of the sealant film material is optimized so as to ensure heat seal strength. I think.

  On the contrary, when the crystallinity of the sealant film is low, the gas barrier property of the sealant film is lowered. Therefore, in order to obtain the effect of improving the gas barrier property by the sea run and the thickness reduction, the crystallinity needs to be 65% or more.

  As a result, when the degree of crystallinity of the sealant film is 85% or less and 65% or more, sufficient heat seal strength and excellent pinhole resistance are obtained while ensuring an excellent gas barrier property as a cover material of the vacuum heat insulating material. Can be provided.

  In addition, the measuring method of crystallinity can apply a well-known method, and can measure it with a X ray method or a specific gravity measuring method.

  According to a third aspect of the present invention, the sealant film according to the first or second aspect is formed by a T-die casting method.

  It was found that when a thin sealant film was applied, the uneven thickness of the sealant film greatly affected the sealing characteristics, and the vacuum heat insulating material leaked due to the destruction of the sealant film at the thinly uneven thickness portion.

  Generally, a sealant film, which is a thermoplastic film, is formed by a melt extrusion method in which a molten resin is continuously extruded through a die from an extruder, and there are a T-die casting method and an inflation method depending on the type of the die.

  Among these, the sealant film formed by the T-die casting method has almost no uneven thickness and small thickness variation. Therefore, it was found that the sealant film can be applied without problems even when applied to a vacuum insulation material having a small sealant thickness.

  Furthermore, although the detailed mechanism is unknown, the gas permeability per unit thickness of the sealant film formed by the T-die casting method differs between the film thickness direction and the direction perpendicular to the film thickness direction. Low gas permeability in the vertical direction. This is a characteristic not found in a film formed by the inflation method.

  Therefore, when a sealant film formed by the T-die casting method is applied to the outer cover material of the vacuum heat insulating material, the gas permeability entering from the end section of the outer cover material is smaller than the gas permeability in the film thickness direction. Therefore, it can be said that it is effective as a film for a vacuum insulation material.

  According to a fourth aspect of the present invention, the sealant film according to any one of the first to third aspects is a linear low density polyethylene film.

  The linear low density polyethylene film is a sealant film having excellent heat seal strength due to its molecular structure. In particular, it is excellent with respect to contaminant adhesion and sealing.

  Therefore, even in the case of a vacuum heat insulating material to which an outer cover material made of a laminated film having a sealant film having a thickness of 40 μm or less and 20 μm or more is applied, it has sufficient heat seal strength and is also stable in production quality. Without any problem, it is possible to provide a high-quality vacuum heat insulating material excellent in gas barrier properties.

  Even if it is a linear low density polyethylene film, the metallocene linear low density polyethylene film synthesized with a metallocene catalyst has a molecular structure with a narrow molecular weight distribution and a high stereoregularity distribution. Furthermore, it is further excellent in heat seal strength, contaminant adhesion sealability, and pinhole resistance.

  According to a fifth aspect of the present invention, the laminated film according to any one of the first to fourth aspects is formed by dry lamination, and the adhesive comprises an aliphatic polyester polyol and an aliphatic polyester. It is a urethane resin made of isocyanate.

  In general, the elastic modulus of the adhesive and the shear strength of the adhesive are in a proportional relationship, and the shear strength decreases as the elastic modulus decreases. Therefore, when a foreign object pierces a laminated film to which a low elastic modulus adhesive is applied, since the adhesive is a low shear strength layer, the adhesive layer breaks or peels off before it penetrates the laminated film. Therefore, the propagation of the piercing force of the foreign substance in the adhesive layer is blocked, and the generation of pinholes can be suppressed.

  Thus, the means for reducing the elastic modulus of the adhesive applied to the laminated film can be realized by making the adhesive a urethane resin composed of an aliphatic polyester polyol and an aliphatic polyisocyanate.

  With the above configuration, the elastic modulus of the urethane resin that is the adhesive layer is smaller than the elastic modulus of the film that is the adherend, so that when an external force acts in the outward direction that breaks through the laminated film In addition, since the adhesive layer absorbs the distortion, the generation of pinholes due to piercing can be suppressed.

  Therefore, even in the case of a vacuum heat insulating material to which an outer cover material made of a laminated film having a sealant film with a thickness of 40 μm or less and 20 μm or more is applied, the pinhole resistance can be improved, and the high quality excellent in the barrier property Vacuum insulation material can be provided.

In addition, a gravure coater, a reverse coater, etc. can be used for the coating of the adhesive agent at the time of dry lamination. The application amount (solid content) of the adhesive is usually ² to 10 g / m ² , and the laminated film after lamination is usually cured at 20 to 50 ° C. for 20 to 120 hours, whereby the adhesive is completely cured.

  Furthermore, in order for the adhesive material to have low shear strength, it is necessary to have a linear molecular structure on the molecular structure, and it is desirable that the isocyanate component has a bifunctional or bifunctional linear structure. . Therefore, aliphatic polyisocyanates such as hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMDI), and lysine diisocyanate (LDI) are particularly effective for exhibiting a low elastic modulus.

  It is also effective to reduce the crosslinking density of the urethane resin that is an adhesive material. Therefore, it is desirable that the equivalent ratio of polyol and polyisocyanate is 1 or more and 3 or less and that polyisocyanate is excessive, and more desirably, the equivalent ratio is 1 or more and 2 or less. That is, it is desirable to mold by reducing the isocyanate component by 10 to 30 wt% from the manufacturer's recommended blending ratio. By applying such an isocyanate, it is possible to reduce the elastic modulus of the urethane resin constituting the adhesive layer, that is, the shear strength.

The sealant film that can be used in the present invention is preferably a polyethylene film. More preferably, linear low density polyethylene film, or density of 0.940 g / cm ³ or less 0.926 g / cm ³ or more in density polyethylene film are preferable, more preferably in metallocene based linear low density polyethylene film is there.

However, the sealant film may be density 0.945 g / cm ³ or less 0.920 g / cm ³ or more, or that if the crystallinity of the sealant film is 85% or more and 65% or less, applied without problems.

  Also, general industrial materials can be used as the core material, silica or pearlite as powder, urethane foam or styrene foam with closed cells communicating, and fiber body as glass wool, rock wool, slag wool, or For organic systems, polyester fibers can be used.

  However, glass wool is desirable among glass fiber systems from the viewpoint of heat insulation performance and cost. Further, the fiber diameter is not particularly specified, but finer fiber diameters can provide better heat insulation performance, and it is desirable to use those having an average fiber diameter of 3 to 5 μm in consideration of economy.

  Hereinafter, embodiments of the vacuum heat insulating material of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a cross-sectional view of a vacuum heat insulating material according to Embodiment 1 of the present invention. Moreover, FIG. 2 is sectional drawing of the jacket material of the vacuum heat insulating material in Embodiment 1 of this invention.

  In FIG. 1, the vacuum heat insulating material 11 is configured by inserting a core material 12 and an adsorbent 14 into a jacket material 13 and sealing the inside of the jacket material 13 under reduced pressure. The vacuum heat insulating material 11 is produced by drying the core material 12 in a drying furnace at 140 ° C. for 10 minutes, and then inserting the laminated film 13 into a cover material 13 formed into a bag shape by sealing by heat welding. The inside of the jacket material is depressurized so as to be 10 Pa or less, and the opening is hermetically sealed by heat welding.

  At this time, as shown in FIG. 2, the jacket material 13 is composed of a linear low density polyethylene film (25 μm) as the sealant layer 21, an aluminum alloy foil (6 μm) as the metal foil layer 22, and the first plastic in order from the inside. A polyester terephthalate film (12 μm) is applied as the film layer 23, and a nylon film (25 μm) is applied as the second plastic film layer 24.

The linear low density polyethylene film used for the sealant layer 21 has a density of 0.940 g / cm ³ and a crystallinity of 78%, and is formed by a T-die casting method.

Moreover, the adhesive of the adhesive layer 25 between each film applies the urethane resin which consists of aliphatic polyester polyol and aliphatic polyisocyanate, and the amount of adhesives (solid content) will be 3.5 g / m < ² >. Thus, it is applied by a dry lamination method to form a laminated film. At this time, the thickness of the adhesive layer between the respective films was 3 μm, and the total thickness of the laminated film was 77 μm.

The adhesive layer 25 was a urethane resin having a low elastic modulus, and the shear strength of the laminate including the adhesive layer 25 was 300 N / cm ² . In general, when a plastic film is bonded with an adhesive having a low elastic modulus, the peel strength increases, but the shear strength decreases.

  On the other hand, the core material 12 is a laminated body of glass fibers in which webs made of short glass fibers are bonded by physical entanglement, and is obtained by laminating glass wool having an average fiber diameter of 3.5 μm until a predetermined density is used. The glass fiber is molded into a board shape by heating and pressing at 450 ° C., which is lower than the strain point of glass, for 5 minutes.

  The adsorbent 14 uses calcium oxide as a moisture adsorbent.

In addition, the thickness of the vacuum heat insulating material 11 was 10 mm, and the core part density was 245 kg / m ³ .

  About the vacuum heat insulating material 11 produced in this way, the thermal conductivity was measured with an auto lambda manufactured by Eihiro Seiki. The thermal conductivity was measured as the initial thermal conductivity 24 hours after the production of the vacuum heat insulating material, and the thermal conductivity after a temperature acceleration test at 100 ° C. for 50 days was measured as an aging characteristic of the thermal conductivity.

  As a result, the initial heat conductivity of the vacuum heat insulating material 11 was 0.0015 W / mK at an average temperature of 24 ° C., and the heat conductivity after the acceleration test was 0.0040 W / mK, which had excellent heat insulating performance. The thermal conductivity after the acceleration test was targeted to be less than 0.0050 W / mK.

  At this time, the thermal conductivity after the acceleration test was greatly improved to Δ0.0015 W / mK as compared with the conventional product. In addition, despite the thin sealant film of 25 μm, it was possible to produce a high-quality vacuum heat insulating material without problems in heat seal strength and pinhole resistance while ensuring the same productivity as the conventional product. .

The reason for this will be described below. In general, the physical properties of a sealant film vary greatly depending on the density difference. In this case, if the range density of 0.945 g / cm ³ or less 0.920 g / cm ³ or more sealant film, the molecular structure of sealant film is optimized, sufficient heat-sealing strength can be ensured.

Therefore, even in the case of a vacuum heat insulating material to which a jacket material made of a laminated film having a sealant film having a thickness of 40 μm or less and 20 μm or more is applied, the density of the sealant film is 0.945 g / cm ³ or less and 0.920 g / cm ^3. Within the above range, it is possible to provide a high-quality vacuum heat insulating material having sufficient heat seal strength and excellent pinhole resistance while ensuring excellent gas barrier properties.

  However, in order to improve the aging characteristics of the vacuum heat insulating material, it is desirable that the thickness of the sealant film is thinner, but considering the productivity and quality balance of the vacuum heat insulating material, the thickness of the sealant film is desirably 20 μm, and more desirably. Is around 25 μm.

  The thickness of the laminated film is preferably 70 μm or more, more preferably 80 μm or more, and even more preferably 90 μm or more.

  Hereinafter, although the laminated film which comprises the jacket material 13 of the vacuum heat insulating material 11 of this invention using an Example and a comparative example is demonstrated concretely, this invention is not limited only to a present Example. Absent.

  About the physical property of the laminated | multilayer film at the time of changing the structure of the jacket material 13 of the vacuum heat insulating material 11, and the physical property of the vacuum heat insulating material 11, Example 1-6 is set to (Table 1), and Comparative example AG is ( Table 2).

真空断熱材は、実施の形態１と同様の方法で作製しているが、真空断熱材１１の外被材１３の構成を各種変更して作製している。

The vacuum heat insulating material is manufactured by the same method as in the first embodiment, but is manufactured by changing the configuration of the jacket material 13 of the vacuum heat insulating material 11 in various ways.

  The material types of the sealant film shown in (Table 1) and (Table 2) are: A for linear low density polyethylene (T die casting method), B for metallocene linear low density polyethylene (T die casting method), C is medium density polyethylene (T die casting method), and D is linear low density polyethylene (inflation method). The adhesive material type is urethane resin consisting of aliphatic polyester polyol and aliphatic polyisocyanate I, and urethane resin consisting of aromatic polyester polyol and tolylene diisocyanate (TDI).

  In addition, the heat-seal strength measured the tensile strength of the heat-seal part by the claw peeling test. Further, the contaminant adhesion seal strength was measured by carrying out heat seal in a state where a predetermined amount of silica powder was bitten into the heat seal portion, and then measuring the tensile strength of the heat seal portion by a cleaving test. Furthermore, the pinhole resistance was evaluated for the presence or absence of pinholes in the jacket material in a state where a predetermined amount of glass fine powder was sealed inside the vacuum heat insulating material and sealed under reduced pressure.

  The thermal conductivity of the vacuum heat insulating material was measured with an auto lambda manufactured by Eihiro Seiki. The thermal conductivity was measured as the initial thermal conductivity 24 hours after the production of the vacuum heat insulating material, and the thermal conductivity after a temperature acceleration test at 100 ° C. for 50 days was measured as an aging characteristic of the thermal conductivity. In addition, the thermal conductivity after an acceleration test made less than 0.0050 W / mK pass.

Example 1
The vacuum heat insulating material 11 was produced by the same method as in the first embodiment except for the jacket material 13. In order from the inside, the jacket material 13 is a linear low-density polyethylene film (40 μm) as the sealant layer 21, an aluminum alloy foil (6 μm) as the metal foil layer 22, and a polyester terephthalate film (12 μm as the first plastic film layer 23. ), A nylon film (25 μm) is applied as the second plastic film layer 24.

  At this time, the thermal conductivity after the acceleration test of the vacuum heat insulating material was 0.0049 W / mK, an improvement of 0.0006 W / mK compared to the conventional product, and cleared the target of less than 0.0050 W / mK.

  In addition, as a laminated film physical property, a vacuum heat insulating material having no particular problems such as heat seal strength, contaminant adhesion seal strength, and pinhole resistance, and no problem in quality and productivity could be produced.

(Example 2)
The vacuum heat insulating material 11 was produced by the same method as in the first embodiment except for the jacket material 13. In order from the inside, the jacket material 13 is a linear low-density polyethylene film (20 μm) as the sealant layer 21, an aluminum alloy foil (6 μm) as the metal foil layer 22, and a polyester terephthalate film (12 μm as the first plastic film layer 23. ), A nylon film (25 μm) is applied as the second plastic film layer 24.

  At this time, the thermal conductivity after the accelerated test of the vacuum heat insulating material was 0.0038 W / mK, an improvement of 0.00017 W / mK compared with the conventional product, and greatly cleared the target of less than 0.0050 W / mK.

  In addition, as a laminated film physical property, a vacuum heat insulating material having no particular problems such as heat seal strength, contaminant adhesion seal strength, and pinhole resistance, and no problem in quality and productivity could be produced.

(Example 3)
The vacuum heat insulating material 11 was produced by the same method as in the first embodiment except for the jacket material 13. In order from the inside, the jacket material 13 is a linear low-density polyethylene film (20 μm) as the sealant layer 21, an aluminum alloy foil (6 μm) as the metal foil layer 22, and a polyester terephthalate film (12 μm as the first plastic film layer 23. ), A nylon film (25 μm) is applied as the second plastic film layer 24.

The density of the linear low density polyethylene film was 0.945 g / cm ³ .

  At this time, the thermal conductivity after the acceleration test of the vacuum heat insulating material was 0.0035 W / mK, an improvement of 0.0020 W / mK compared to the conventional product, and greatly cleared the target of less than 0.0050 W / mK. The reason why the thermal conductivity after the accelerated test of the vacuum heat insulating material is lower than that in Example 2 is that the gas permeability of the material is reduced due to the increase in crystallinity of 83% with increasing density. I think.

  In addition, as a laminated film physical property, a vacuum heat insulating material having no particular problems such as heat seal strength, contaminant adhesion seal strength, and pinhole resistance, and no problem in quality and productivity could be produced.

Example 4
The vacuum heat insulating material 11 was produced by the same method as in the first embodiment except for the jacket material 13. In order from the inside, the jacket material 13 is a linear low-density polyethylene film (20 μm) as the sealant layer 21, an aluminum alloy foil (6 μm) as the metal foil layer 22, and a polyester terephthalate film (12 μm as the first plastic film layer 23. ), A nylon film (25 μm) is applied as the second plastic film layer 24.

The density of the linear low density polyethylene film was 0.920 g / cm ³ .

  At this time, the thermal conductivity after the acceleration test of the vacuum heat insulating material was 0.0040 W / mK, an improvement of 0.0015 W / mK compared to the conventional product, and greatly cleared the target of less than 0.0050 W / mK. Compared to Example 2, the thermal conductivity after the accelerated test of the vacuum heat insulating material increased because the crystallinity decreased to 72% as the density decreased, and the gas permeability of the sealant material increased. I think that is a factor.

  On the other hand, as for the laminated film physical properties, a vacuum heat insulating material superior in quality and productivity as compared with Example 2 such as heat seal strength, contaminant adhesion seal strength, and pinhole resistance could be produced. This is considered to be an effect of reducing the density of the linear low-density polyethylene film.

(Example 5)
The vacuum heat insulating material 11 was produced by the same method as in the first embodiment except for the jacket material 13. In order from the inside, the jacket material 13 is a metallocene linear low-density polyethylene film (20 μm) as the sealant layer 21, an aluminum alloy foil (6 μm) as the metal foil layer 22, and a polyester terephthalate film as the first plastic film layer 23. (12 μm), a nylon film (25 μm) is applied as the second plastic film layer 24.

The density of the linear low density polyethylene film was 0.940 g / cm ³ .

  At this time, the thermal conductivity after the accelerated test of the vacuum heat insulating material was 0.0038 W / mK, an improvement of 0.0017 W / mK compared to the conventional product, and greatly cleared the target of less than 0.0050 W / mK.

  In addition, as the laminated film physical properties, there is no particular problem such as heat seal strength, cross adherence seal strength, and pinhole resistance, and a vacuum heat insulating material with higher quality and productivity than Example 2 can be produced. It was. This is because the metallocene linear low density polyethylene which changed the synthetic catalyst of the linear low density polyethylene currently applied as a sealant film material is applied.

(Example 6)
The vacuum heat insulating material 11 was produced by the same method as in the first embodiment except for the jacket material 13. In order from the inside, the jacket material 13 is a medium density polyethylene film (20 μm) as the sealant layer 21, an aluminum alloy foil (6 μm) as the metal foil layer 22, a polyester terephthalate film (12 μm) as the first plastic film layer 23, A nylon film (25 μm) is applied as the second plastic film layer 24.

The density of the medium density polyethylene film was 0.940 g / cm ³ .

  At this time, the thermal conductivity after the acceleration test of the vacuum heat insulating material was 0.0036 W / mK, an improvement of 0.0019 W / mK compared to the conventional product, and greatly cleared the target of less than 0.0050 W / mK.

  In addition, as a laminated film physical property, a vacuum heat insulating material having no particular problems such as heat seal strength, contaminant adhesion seal strength, and pinhole resistance, and no problem in quality and productivity could be produced.

(Comparative Example A)
The vacuum heat insulating material 11 was produced by the same method as in the first embodiment except for the jacket material 13. In order from the inside, the jacket material 13 is composed of a linear low density polyethylene film (45 μm) as the sealant layer 21, an aluminum alloy foil (6 μm) as the metal foil layer 22, and a polyester terephthalate film (12 μm as the first plastic film layer 23. ), A nylon film (25 μm) is applied as the second plastic film layer 24.

The density of the linear low density polyethylene film was 0.940 g / cm ³ .

  At this time, the thermal conductivity after the accelerated test of the vacuum heat insulating material could not clear the target 0.0050 W / mK, which is 0.0055 W / mK.

(Comparative Example B)
The vacuum heat insulating material 11 was produced by the same method as in the first embodiment except for the jacket material 13. In order from the inside, the jacket material 13 is a linear low-density polyethylene film (15 μm) as the sealant layer 21, an aluminum alloy foil (6 μm) as the metal foil layer 22, and a polyester terephthalate film (12 μm as the first plastic film layer 23. ), A nylon film (25 μm) is applied as the second plastic film layer 24.

  At this time, the initial thermal conductivity of the vacuum heat insulating material was 0.0080 W / mK after the production of 24 hours, and the predetermined performance was not obtained. This is considered to be caused by a slow leak in the heat seal part due to the fact that the thickness of the linear low density polyethylene film applied to the sealant layer 21 is as thin as 15 μm and the heat seal quality deteriorates due to insufficient heat seal strength and the like.

(Comparative Example C)
The vacuum heat insulating material 11 was produced by the same method as in the first embodiment except for the jacket material 13. In order from the inside, the jacket material 13 includes a linear low-density polyethylene film (20 μm) as the sealant layer 21, an aluminum alloy foil (6 μm) as the metal foil layer 22, and a polyester terephthalate film (12 μm) as the first plastic film layer 23. ), A nylon film (15 μm) is applied as the second plastic film layer 24.

  At this time, the initial thermal conductivity of the vacuum heat insulating material was 0.0085 W / mK after the production of 24 hours, and the predetermined performance was not obtained. This is judged because the linear low density polyethylene film applied to the sealant layer 21 has a thickness of 20 μm, but the total thickness of the laminated film is as thin as 62 μm, and has not cleared the standard in the pinhole resistance test. This is considered to be due to slow leaks caused by pinholes due to insufficient absolute strength of the laminated film.

(Comparative Example D)
The vacuum heat insulating material 11 was produced by the same method as in the first embodiment except for the jacket material 13. In order from the inside, the jacket material 13 is a linear low-density polyethylene film (20 μm) as the sealant layer 21, an aluminum alloy foil (6 μm) as the metal foil layer 22, and a polyester terephthalate film (12 μm as the first plastic film layer 23. ), A nylon film (25 μm) is applied as the second plastic film layer 24.

  At this time, as the linear low density polyethylene film, a sealant film formed by the inflation method from the conventional T-die method is applied.

  The thermal conductivity after the accelerated test of the vacuum heat insulating material is 0.0045 W / mK, which is 0.00010 W / mK compared to the conventional product, but is 0.00007 W / mK worse than that of Example 2. It was. This is considered to be due to a difference in the molding method of the sealant film.

  On the other hand, although the laminated film physical properties did not lead to the leakage of the vacuum heat insulating material, the heat seal strength and the foreign matter adhesion seal strength were lower than the standard values, and there was a possibility of problems in quality and productivity.

(Comparative Example E)
The vacuum heat insulating material 11 was produced by the same method as in the first embodiment except for the jacket material 13. In order from the inside, the jacket material 13 is a linear low-density polyethylene film (20 μm) as the sealant layer 21, an aluminum alloy foil (6 μm) as the metal foil layer 22, and a polyester terephthalate film (12 μm as the first plastic film layer 23. ), A nylon film (25 μm) is applied as the second plastic film layer 24.

The density of the linear low density polyethylene film was 0.915 g / cm ³ .

  At this time, although the thermal conductivity after the accelerated test of the vacuum heat insulating material is 0.0052 W / mK, which is an improvement of 0.0003 W / mK compared to the conventional product, the target thermal conductivity is less than 0.0050 W / mK. Did not clear.

This is because the density of the linear low-density polyethylene film is further reduced as compared with Example 4 to 0.915 g / cm ³ , so that the crystallinity of the film is reduced to 60%, and the gas of the film The cause is considered to be the increase in transmittance.

(Comparative Example F)
The vacuum heat insulating material 11 was produced by the same method as in the first embodiment except for the jacket material 13. In order from the inside, the jacket material 13 includes a linear low-density polyethylene film (20 μm) as the sealant layer 21, an aluminum alloy foil (6 μm) as the metal foil layer 22, and a polyester terephthalate film (12 μm as the first plastic film layer 23. ), A nylon film (25 μm) is applied as the second plastic film layer 24.

Further, the density of the linear low density polyethylene film was 0.950 g / cm ^3. At this time, the thermal conductivity after the accelerated test of the vacuum heat insulating material was 0.0182 W / mK, which was worse than the conventional product. This is because the density of the linear low-density polyethylene film applied to the sealant layer 21 is 0.950 g / cm ^3, which is larger than that of Example 3, and the physical properties of the laminated film were lowered due to the high brittleness of the sealant film. Think of it as a factor.

(Comparative Example G)
The vacuum heat insulating material 11 was produced by the same method as in the first embodiment except for the jacket material 13. In order from the inside, the jacket material 13 includes a linear low-density polyethylene film (20 μm) as the sealant layer 21, an aluminum alloy foil (6 μm) as the metal foil layer 22, and a polyester terephthalate film (12 μm) as the first plastic film layer 23. ), A nylon film (25 μm) is applied as the second plastic film layer 24.

The density of the linear low density polyethylene film was 0.940 g / cm ³ . At the same time, the adhesive material type is changed from a urethane resin composed of an aliphatic polyester polyol and an aliphatic polyisocyanate to a urethane resin composed of an aromatic polyester polyol and tolylene diisocyanate (TDI).

  At this time, the thermal conductivity after the acceleration test of the vacuum heat insulating material was 0.0104 W / mK, which was worse than the conventional product. This is considered to be due to the fact that the pinhole resistance was lowered because the adhesive material type was changed to a urethane resin composed of aromatic polyester polyol and tolylene diisocyanate (TDI).

  As described above, since the vacuum heat insulating material according to the present invention is excellent in initial heat insulating performance and can maintain excellent heat insulating performance over a long period of time, high heat insulating performance can be obtained with a thinner thickness. Therefore, in addition to heat insulation and cooling applications such as refrigerators and cooler boxes, the present invention can be applied to heat insulation applications that require high heat insulation performance in a narrow space such as liquid crystal projectors, copy machines, and notebook computers.

Sectional drawing of the vacuum heat insulating material in Embodiment 1 of this invention Sectional drawing of the jacket material of the vacuum heat insulating material in the same embodiment

Explanation of symbols

11 Vacuum insulation material 12 Core material 13 Cover material 21 Sealant layer 25 Adhesive layer

Claims (5)

In the vacuum heat insulating material, in which the core material is covered with an outer cover material made of a laminated film having an innermost layer of a sealant film having a thickness of 40 μm or less and 20 μm or more, and the inside of the outer cover material is sealed under reduced pressure. density of the 0.945 g / cm ³ or less 0.920 g / cm ³ or more, and the vacuum heat insulating material total thickness is 70μm or more of the multilayer film.   The vacuum heat insulating material according to claim 1, wherein the crystallinity of the sealant film is 85% or less and 65% or more.   The vacuum heat insulating material according to claim 1 or 2, wherein the sealant film is formed by a T-die casting method.   The vacuum heat insulating material according to any one of claims 1 to 3, wherein the sealant film is a linear low-density polyethylene film.   The vacuum heat insulating material according to any one of claims 1 to 4, wherein the laminated film is formed by dry lamination, and the adhesive is a urethane resin composed of an aliphatic polyester polyol and an aliphatic polyisocyanate.

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