JP2007002996A - Method for manufacturing vacuum heat insulating material and vacuum heat insulating material manufactured by same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum heat insulating material with excellent heat insulating performance using a laminated body of a short fiber web for a core material. <P>SOLUTION: Glass short fiber constructing the laminated body is low brittleness and high fiber strength short fiber which does not fracture easily even if stress is applied due to compression of the core material 2 by atmospheric air after vacuum wrapping by an outer coating material 3, protects a shape of the core material 2 against atmospheric pressure with a fewer number of contact points to reduce a number of heat conduction routes in a thickness direction while keeping a gap of the core material 2. When operation quickly releasing compression after compressing the laminated body to 1,013 hPa is repeated, thickness of the laminated body when compression strength gets to 300 hPa at a time of first compression is defined as reference thickness, and ratio of compression strength when the thickness of the laminated body is the reference thickness at a time of second compression and 300 hPa is 0.65 or greater. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  As the core material used for the vacuum heat insulating material, an inorganic compound having a low thermal conductivity and a low gas generation is suitable. In particular, a vacuum heat insulating material using a glass fiber laminate as a core material is known to have excellent heat insulating performance, and is shown in FIG. 5 as an example of a core material constituting the vacuum heat insulating material. There is.

  FIG. 5 shows that the inorganic fine fibers 91a are randomly laminated so that the length direction thereof is perpendicular to the heat transfer direction and the length directions of the inorganic fine fibers 91a intersect each other. It is provided with a penetration fiber 91b that forms a high-density inorganic fine fiber mat 9 by being driven into contact with the laminated thin fiber 91a in parallel with the heat transfer direction. It has been proposed to form a core material by superimposing sheets (N sheets) (see, for example, Patent Document 1).

  In the conventional vacuum heat insulating material configured as described above, since the inorganic small-diameter fibers 91a are arranged randomly and perpendicularly to the heat transfer direction, the fibers 91a are in point contact with each other. The contact heat resistance at the contact point is large, and the heat transfer amount in the core thickness direction is small.

  However, only the fiber 91a arranged perpendicular to the heat transfer direction reduces the compression resistance against atmospheric pressure acting in the heat transfer direction, and the core material is compressed by the atmospheric pressure acting after vacuum packaging, making it difficult to ensure thickness. Become.

Therefore, the penetration fibers 91b are partially arranged in parallel with the heat transfer direction. However, since the heat insulation performance is lowered by the penetration fibers 91b, a core material is formed by superimposing a plurality of (N) inorganic thin fiber mats 9, and the amount of heat transferred by the penetration fibers 91b is reduced.
Japanese Examined Patent Publication No. 7-103955

  However, in the above conventional configuration, even if the core material is formed by superimposing a plurality of (N) inorganic thin fiber mats 9 and the amount of heat transfer by the penetration fibers 91b is reduced, it is arranged in parallel to the heat transfer direction. Since the penetration fibers 91b, that is, the fibers 91b themselves act as heat bridges that directly transfer heat, it is difficult to reduce the amount of heat transfer. Moreover, since the heat | fever conducts with the heat conductivity intrinsic | native to glass material in the fiber 91b arrange | positioned in parallel with the heat transfer direction, the amount of heat transfer increases in proportion to the number of fibers arrange | positioned in parallel with the heat transfer direction.

  Therefore, the subject that the heat insulation performance of the vacuum heat insulating material deteriorated in proportion to the quantity of the glass fiber 91b arrange | positioned in parallel with the heat-transfer direction occurred.

  On the other hand, in the core material comprised only of the glass fiber 91a arrange | positioned substantially perpendicular | vertical with respect to the heat transfer direction, there existed a subject that the heat insulation performance of a vacuum heat insulating material deteriorated for the following reason.

  When the glass fiber constituting the core material does not have sufficient strength, the fiber constituting the core material is bent or broken by atmospheric pressure. When the bending of the fibers proceeds, the void portion of the core material formed by the entanglement between the fibers is crushed, and the number of contact points between the fibers increases. As a result, the number of heat transfer paths increases and, in part, the contact area increases due to contact of the fibers from point contact to line contact, etc., so the contact thermal resistance decreases.

  In addition, when the fiber breaks, as in the case where the bending of the fiber proceeds, the void portion of the core material formed by the entanglement between the fibers is crushed, and the number of contact points between the fibers increases. Specifically, the contact thermal resistance decreases because the contact area increases, for example, where the fiber comes into contact with line contact. Furthermore, the void portion of the core material formed by the entanglement between the fibers is filled with the broken fiber, the void of the core material is further reduced, and the number of contact points of the fiber is also increased.

  For this reason, the amount of heat transfer is increased, the heat insulation performance of the vacuum heat insulating material is reduced, and the thickness of the core material cannot be secured, and the amount of the fibrous substance constituting the core material needs to be increased. There was a problem that the material cost increased.

  The present invention solves the above-described conventional problems, and provides a vacuum heat insulating material that can further improve the heat insulating performance, improve the compression resistance of the core material, and reduce the material cost of the core material. And

  In order to achieve the above object, the vacuum heat insulating material of the present invention is a vacuum heat insulating material obtained by covering a core material composed of a laminate of short glass fibers with a covering material and reducing the pressure inside the covering material, The short glass fibers constituting the laminate are arranged substantially perpendicularly to the heat transfer direction and randomly laminated in the thickness direction of the core material. After the laminate is compressed to 1013 hPa, In the case of repeating the operation of releasing the compression, the thickness of the laminate when the compression strength is 300 hPa at the first compression is a reference thickness, and the ratio of the compression strength at the reference thickness at the second compression to 300 hPa Is 0.65 or more.

  Thus, in this invention, it discovered that the heat insulation performance of a vacuum heat insulating material improved by applying to the core material of a vacuum heat insulating material the laminated body with a small fall of the compressive strength in a certain reference thickness at the time of repeated compression. It is.

  As a result, the short glass fibers constituting the laminate are low in brittleness and strong in fiber strength. Therefore, even when compressed by atmospheric pressure, the fibers are not easily bent or broken, and voids formed by entanglement of fibers. Is retained. In addition, since the fiber itself is difficult to break, the original fiber length is long since the fiber was manufactured.

  As a result, even if the glass short fiber is a layered body that is arranged substantially perpendicularly to the heat transfer direction and is randomly stacked and laminated in the thickness direction of the core material, the glass fiber has the same effect as the leaf spring, Atmospheric pressure can be maintained with a smaller number of contact points, and the number of heat transfer paths in the thickness direction of the core material is reduced.

  In addition, the short glass fibers are arranged in a direction perpendicular to the heat transfer direction and randomly arranged in the thickness direction of the core material, but the fiber length of the short glass fibers is longer than the conventional product. Further, the laminated state is further improved, and the heat transfer distance in the core thickness direction is increased.

  For the above reason, since the heat transfer amount in the thickness direction of the core material decreases, the heat insulating performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, the core material can be reduced in density, and at the same time, a vacuum heat insulating material that realizes cost reduction of the core material is provided. be able to.

  Further, another vacuum heat insulating material of the present invention is a vacuum heat insulating material obtained by covering a core material made of a short glass fiber laminate with an outer covering material and reducing the pressure inside the outer covering material. The short glass fibers that are configured are arranged in a direction perpendicular to the heat transfer direction and randomly arranged and laminated in the thickness direction of the core material. After the laminated body is compressed to 1013 hPa, the compression is quickly released. In the case of repeating the operation, the thickness of the laminate when the compressive strength is 300 hPa at the first compression, the thickness of the laminate when the compressive strength is 300 hPa at the second compression, and the reference The ratio to the thickness is 0.9 or more.

  In this invention as well, the heat insulation performance of the vacuum heat insulating material is improved because the amount of heat transfer in the thickness direction of the core material is reduced by the same action as the previous invention.

  Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced. As a result, it is possible to provide a vacuum heat insulating material that realizes cost reduction of the core material.

  Moreover, like the previous invention, management can be easily performed by substituting the compression characteristics in the laminated body of short glass fibers, and the entire image of the laminated body can be easily grasped more specifically.

  In the vacuum heat insulating material of the present invention, the heat transfer performance in the thickness direction of the core material is reduced, so that the heat insulating performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material is increased, and the density of the core material can be reduced. Therefore, it is possible to provide a vacuum heat insulating material that realizes high performance and cost reduction of the core material.

  The invention according to claim 1 is a vacuum heat insulating material obtained by covering a core material composed of a laminate of short glass fibers with an outer covering material and reducing the pressure inside the outer covering material, and the glass constituting the laminated body The short fibers are arranged in a direction substantially perpendicular to the heat transfer direction and randomly stacked in the thickness direction of the core material, and the operation of releasing the compression immediately after compressing the laminate to 1013 hPa. In the case of repetition, the thickness of the laminate when the compression strength is 300 hPa at the first compression is the reference thickness, and the ratio of the compression strength at the reference thickness at the second compression to 300 hPa is 0.65 or more. It is a vacuum heat insulating material.

  In general, the destruction of the glass composition is a typical brittle fracture from a low temperature to a normal temperature, and the fracture occurs rapidly under a critical stress. Such fracture of a brittle solid occurs when the bonds between atoms are broken by the tensile stress and the atoms are separated.

  However, since there are actually flaws called large and small Griffith flows on the surface and inside of the glass, these become stress concentration sources, and breakage occurs under load stress much lower than the theoretical value. This is one of the causes of glass brittleness.

  Even in the case of a short glass fiber, the fiber is less likely to break against a load stress such as compression by reinforcing the fiber and making the glass itself low brittle. As a result, the laminate is less reduced in compressive strength at the reference thickness during repeated compression.

  Therefore, even in a vacuum heat insulating material in which a core material composed of a laminate of short glass fibers is covered with an outer cover material and the inside is decompressed, the fibers constituting the core material by compressing the core material by atmospheric pressure after vacuum packaging Even when a tensile stress is applied to the fiber, the fiber is not easily broken, and the voids of the core material formed by the entanglement of the fiber are maintained. This means that the core material shape can be maintained against the atmospheric pressure with a smaller number of fiber contact points, and the number of heat transfer paths in the core material thickness direction is reduced. Become.

  Thus, by applying the short glass fiber having low brittleness and high fiber strength to the core material, the heat transfer performance in the thickness direction of the core material is reduced, so that the heat insulation performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and at the same time, the density of the core material can be reduced. As a result, it is possible to provide a vacuum heat insulating material that realizes cost reduction of the core material.

  Further, when the glass short fiber laminate is repeatedly compressed, the glass short fiber laminate is vacuumed so that the ratio of the compression strength at the reference thickness at the second compression to 300 hPa is 0.65 or more. Since the heat transfer amount in the thickness direction of the core material is reduced by using the core material of the heat insulating material, the heat insulating performance of the vacuum heat insulating material is improved.

  Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced. As a result, it is possible to provide a vacuum heat insulating material that realizes cost reduction of the core material.

  Moreover, it is essential to manage the brittle characteristics of short glass fibers by the tensile strength of the fibers. However, in practice, the short glass fibers constituting the laminate have a wide distribution in the fiber strength, and therefore the measurement required to grasp the overall image of the short glass fibers requires a great deal of labor. Therefore, as shown in the present invention, management can be easily performed by substituting the compression characteristics of the short glass fiber laminate, and the overall image of the laminate can be more easily grasped.

  In short, it has been newly found that the repeated compressive strength ratio obtained by this test method has a good correlation with the thermal conductivity of the vacuum heat insulating material.

  On the other hand, the amount of compression at the time of repeated compression is set to 1013 hPa in terms of compressive strength is set because the vacuum heat insulating material in which the laminated body is vacuum-packed is constantly subjected to atmospheric pressure, but it is a problem that it slightly varies Absent. However, when the pressure is increased to about twice the atmospheric pressure, the fiber breaks even in the case of low brittleness or high strength fiber, so the compressive strength at the reference thickness at the second compression and 300 hPa Since the ratio may be less than 0.65, the compression strength during repeated compression is desirably 1013 hPa.

  Moreover, the reference thickness at the time of repeated compression is the thickness of the laminate at 300 hPa. The compression strength ratio at the time of repeated compression varies depending on the compression strength as the reference thickness, but the laminate at 300 hPa This is because the correlation with the heat insulating performance of the vacuum heat insulating material becomes clear when the thickness is used as a reference.

  The compression strength ratio in the repeated compression test is a value obtained by dividing the second compression strength at the reference thickness by 300 hPa that sets the reference thickness.

  The invention according to claim 2 is a vacuum heat insulating material obtained by covering a core material composed of a laminate of short glass fibers with an outer covering material and reducing the pressure inside the outer covering material, and the glass constituting the laminated body The short fibers are arranged in a direction substantially perpendicular to the heat transfer direction and randomly stacked in the thickness direction of the core material, and the operation of releasing the compression immediately after compressing the laminate to 1013 hPa. In the case of repetition, the thickness of the laminate when the compressive strength is 300 hPa at the first compression is the reference thickness, and the thickness of the laminate when the compressive strength is 300 hPa at the second compression and the reference thickness The vacuum heat insulating material has a ratio of 0.9 or more.

  When the laminate of short glass fibers is repeatedly compressed, the short glass fibers have a ratio of 0.9 or more to the thickness of the laminate when the compressive strength is 300 hPa during the second compression. By using the laminated body as the core material of the vacuum heat insulating material, the heat transfer performance in the thickness direction of the core material is reduced by the same action as the invention of claim 1, so the heat insulating performance of the vacuum heat insulating material is improved. To do.

  Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced. As a result, it is possible to provide a vacuum heat insulating material that realizes cost reduction of the core material.

  As in the first aspect of the invention, management can be easily performed by substituting the compression characteristics of the short glass fiber laminate, and the overall image of the laminate can be more easily grasped.

  In addition, when the laminated body of short glass fibers is formed into a board shape by binder or thermoforming, the heat transfer amount in the thickness direction of the core material is reduced, so that the heat insulating performance of the vacuum heat insulating material is improved.

  Further, since the compression resistance of the core material is improved, the porosity of the core material can be increased and the density of the core material can be reduced. As a result, it is possible to provide a vacuum heat insulating material that realizes cost reduction of the core material.

  Furthermore, when the short glass fiber laminate is formed into a board by binder or thermoforming, the bulk of the laminate can be reduced and the board is given rigidity, so when the board size is large However, its handling is greatly improved.

  In addition, also when it uses as a core material without shape | molding the laminated body of a glass short fiber in board shape, since the heat transfer amount of the thickness direction of a core material falls, the heat insulation performance of a vacuum heat insulating material improves.

  Further, since the compression resistance of the core material is improved, the porosity of the core material can be increased and the density of the core material can be reduced. As a result, it is possible to provide a vacuum heat insulating material that realizes cost reduction of the core material.

  Moreover, if the laminated body of short glass fibers is applied as a core material without forming into a board shape, the load stress on the short glass fibers constituting the laminated body becomes smaller, and the progress of breakage of the short glass fibers is most suppressed. Therefore, more excellent heat insulation performance can be realized in the vacuum heat insulating material.

  Thus, the glass short fiber applied as a core material of a vacuum heat insulating material can improve the heat insulation performance of a vacuum heat insulating material, so that it is low brittle and the fiber strength is large. Moreover, the density reduction of a vacuum heat insulating material is realizable, so that the fiber strength is large.

  It is essential to control the brittle properties of short glass fibers by the tensile strength of the fibers. However, in practice, the short glass fibers have a wide distribution of fiber strength, and the measurement required to grasp the overall image of the short glass fibers requires a great deal of labor. Therefore, as shown in the present invention, it is desirable to manage by substituting the compression characteristics in the laminated body of short glass fibers.

  Thus, in order to improve the thermal conductivity of the vacuum heat insulating material, it is desirable that the reduction in the compressive strength at the reference thickness during repeated compression is small in the operation of repeatedly compressing and releasing the glass short fiber laminate.

  Hereinafter, the test method for obtaining the repeated compressive strength ratio of the present invention will be specifically described.

  (1) As a pretreatment of the test sample, in order to remove the compression history of the sample due to vacuum packaging or packing, the sample is first compressed to 300 hPa.

  (2) As the first compression, the test sample is compressed to 1013 hPa and quickly released to a predetermined thickness. The thickness at which the compression strength becomes 300 hPa in this compression process is taken as the reference thickness.

  (3) The same compression as the first compression is performed again until the second compression to 1013 hPa. In this compression process, the compressive strength at the reference thickness is measured.

  (4) The repeated compression strength ratio is calculated from the following equation.

Repeated compressive strength ratio = compressive strength at the standard thickness during the second compression / 300 hPa
At this time, a general autograph can be used as the repeated compression test apparatus. As an example of the test conditions, the compression speed is 10 mm / min, the compression jig is an iron circular shape having a diameter of 100 mm both in the upper and lower sides, the test sample is 200 mm × 200 mm in size, and the basis weight is 2500 g / m ² ± 15%. The center part of the sample is compressed and the compressive strength test is repeatedly performed.

  As the short glass fiber that can be used in the present invention, a known fiber can be used, but it is desirable that the fiber diameter is small and the thermal conductivity of the material is small, and the tensile strength of the fiber is 0.5 GPa or more. It is more desirable.

  The laminated body is preferably formed by laminating webs in which short glass fibers are randomly arranged so as to be perpendicular to the heat transfer direction (thickness direction) and the fibers are formed so as to be in point contact with each other. Further, the laminate formed by laminating the webs is more preferably a laminate in which the webs are joined by minimum entanglement of fibers capable of maintaining the integrity of the laminate, and are uniformly laminated in the thickness direction. is there. By setting it as such a laminated body, the contact heat resistance between fibers becomes more dominant than the heat conductivity intrinsic | native to a glass composition in the heat transfer amount of a core material thickness direction.

  As an example, the general-purpose glass composition has a thermal conductivity of about 1 W / mK at room temperature, but a laminated body in which glass fibers are arranged substantially perpendicular to the heat transfer direction, that is, a laminated body in which webs are laminated. In the case of a vacuum heat insulating material having a body as a core material, the apparent thermal conductivity related to the solid component of the laminate is 1/100 or less of the glass composition itself.

  The fiber diameter is not particularly specified, but finer fiber diameter can provide better heat insulation performance. However, it is desirable to use one having an average fiber diameter of 3 to 5 μm from the viewpoint of economy.

  On the other hand, an example of a method for making short glass fibers low brittle and high in strength is as follows.

  The short glass fiber applicable to the present invention can make the short glass fiber low brittle and high in strength by optimizing the glass composition and the manufacturing process. Among these, methods for increasing the strength of short glass fibers by optimizing the manufacturing process include a method called a chemical strengthening method or an ion exchange method, and a method called a heating rapid cooling method or an air cooling strengthening method.

  The chemical strengthening method is a method in which the glass surface is eroded with hydrofluoric acid or the like, and thereby the Griffith flow existing on the glass surface can be removed, so that the brittleness and strength of the short glass fiber can be improved.

  In addition, the ion exchange method is a method in which a high compressive stress layer is applied to the glass surface in advance by replacing sodium ions on the glass surface with potassium ions having a large molecular diameter. Similarly, the brittleness and strength of the glass are improved. it can.

  However, the heating and cooling method is most used industrially. This is processed by spraying low-temperature air on heated glass, and by applying a high compressive stress layer to the surface of the glass in advance, durability against tensile stress is improved. This method can be carried out in the same manner for glass fibers, and the glass fibers are reinforced by blowing cooling air to the high-temperature fibers immediately after fiberization, so that the glass fibers can be efficiently processed.

  As mentioned above, although the glass strengthening method utilized industrially was shown, the method of strengthening the mechanical strength of glass fiber is not limited to what was mentioned above, A well-known method is applicable.

  On the other hand, it is more desirable that the laminate film forming the covering material that can be used in the present invention is composed of a plastic film having at least one of a metal foil layer and a vapor deposition layer in order to impart high gas barrier properties. At this time, a known material can be used for the metal foil layer and the vapor deposition layer, and is not particularly specified.

  In addition, the lamination film is preferably formed by a dry lamination method using an adhesive for dry lamination, but an extrusion lamination method in which a part of the laminate film is melt extruded using an olefin resin is applied. Also good.

  Hereinafter, embodiments 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 schematic cross-sectional view of a vacuum heat insulating material in Embodiment 1 of the present invention.

  In FIG. 1, the vacuum heat insulating material 1 is configured by inserting a core material 2 and an adsorbent 4 into an outer cover material 3 and reducing the pressure inside. At this time, the core material 2 is adjusted so that the vacuum heat insulating material has a thickness of 10 mm.

  The vacuum heat insulating material 1 is prepared by drying the core material 2 in a drying furnace at 140 ° C. for 20 minutes, and then inserting the three sides of the laminate film into the envelope material 3 formed into a bag shape by heat sealing. The pressure inside the jacket 3 is reduced to 10 Pa or less, and the opening is hermetically sealed by heat welding.

  On the other hand, the glass short fiber applied to the core material 2 is glass wool having an average fiber diameter of 3.5 μm. However, the glass wool uses a general-purpose soda-lime glass composition, but immediately after fiberization, the glass wool is rapidly cooled by blowing cooling air to reinforce the fibers.

  The core material 2 is produced by laminating glass wool made of short glass fiber webs to a predetermined thickness, and molding a laminated body in which the webs are joined by entanglement. Then, the board-shaped core material is shape | molded by thermoforming the laminated body of a short glass fiber with a hot press at 450 degreeC lower than the distortion point of glass for 5 minutes.

  In addition to the above method, a board-like core material having higher rigidity can be formed by applying a binder during hot pressing. These can be determined in consideration of the required quality and productivity of the vacuum heat insulating material.

  The jacket material 3 is composed of a plastic laminate film in which a polyethylene terephthalate film (12 μm) is applied to the outermost layer, an aluminum foil (6 μm) is applied to the intermediate layer, and a linear low density polyethylene film (50 μm) is applied to the heat-welded layer. .

  The adsorbent 4 uses calcium oxide as a moisture adsorbent.

  About the vacuum heat insulating material 1 produced in this way, the thermal conductivity was measured with an auto lambda manufactured by Eihiro Seiki. As a result, the heat conductivity of the vacuum heat insulating material 1 has an excellent heat insulating performance of 0.0015 W / mK at an average temperature of 24 ° C., and the compression strength ratio in the repeated compression test of the laminate is 0.8. there were.

  This means that the thermal conductivity is reduced by 0.0004 W / mK compared to a vacuum heat insulating material in which a core material is formed from a laminate of conventional short glass fibers having a compression strength ratio of less than 0.65 in a repeated compression test. I understood.

Similarly, the core material density required to make the vacuum heat insulating material 1 10 mm thick is conventionally 250 kg / m ³ , but in the present embodiment it is 240 kg / m ³ .

  The reason why such a result was obtained is that the compression strength ratio in the repeated compression test of the laminate is 0.8, so even if the core material is compressed by atmospheric pressure compared to the conventional product, the bending of the fiber It is considered that breakage hardly occurs, voids formed by fiber entanglement are maintained, and atmospheric pressure can be maintained with a smaller number of fiber contact points.

  As a result, since the amount of heat transfer in the thickness direction of the core material is reduced, the heat insulating performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced. Therefore, in this Embodiment, since the usage-amount of glass wool can be reduced 4%, reduction of raw material cost is also realizable.

  In this embodiment, as the short glass fibers forming the core material, glass wool, which is a general-purpose industrial material, is applied, and the heating and quenching method is performed so that the compression strength ratio in the repeated compression test of the laminate is 0.65 or more. The fiber is reinforced and applied.

  However, the short glass fiber that can be applied to the core material can be applied without any particular problem as long as the short glass fiber has low brittleness and high strength. However, desirably, a laminate of short glass fibers having a compression strength ratio of 0.65 or more in a repeated compression test of the laminate, more desirably, a laminate of short glass fibers having a compression strength ratio of 0.70 or more, More preferably, it is a laminate of short glass fibers having a compressive strength ratio of 0.75 or more.

  In addition, although the compressive strength ratio greatly reduces the thermal conductivity at the boundary of 0.65, if the compressive strength ratio exceeds 0.75, no further decrease in the thermal conductivity can be confirmed. Therefore, when the compressive strength ratio is in the range of 0.65 or 0.75, the thermal conductivity tends to decrease as the compressive strength ratio increases.

  The repeated compression test was carried out using an iron circular jig having a diameter of 100 mm using an autograph made by Shimadzu Corporation. At this time, the compression speed was 10 mm / min. In addition, in order to unify the compression load history of the test material and suppress the test variation, this test was performed after the compression treatment was once performed as a pretreatment until the compression strength reached 300 hPa. The compressive strength ratio is shown as an average of n = 3.

(Embodiment 2)
FIG. 2 is a schematic cross-sectional view of the vacuum heat insulating material in Embodiment 2 of the present invention.

  In FIG. 2, the vacuum heat insulating material 11 is configured by inserting a core material 12 and an adsorbent 14 into an outer cover material 13 and reducing the pressure inside. At this time, the core material 12 is adjusted so that the vacuum heat insulating material has a thickness of 10 mm.

  The core material 2 was produced by laminating glass wool made of short glass fiber webs to a predetermined thickness, and molding a laminate in which the webs were joined by entanglement. At this time, the core material 12 is used as a core material without forming the laminated body into a board shape by binder or thermoforming.

  In addition, the vacuum heat insulating material 11 in this Embodiment 2 is the same as that of the material structure in 1st Embodiment, and a preparation method except the manufacturing method of the core material 12 differing.

  The short glass fibers applied to the core material 12 were glass wool having an average fiber diameter of 3.5 μm, and the compression strength ratio in the repeated compression test of the laminate was 0.80.

  About the vacuum heat insulating material 11 produced in this way, the thermal conductivity was measured with an auto lambda manufactured by Eihiro Seiki. As a result, the heat conductivity of the vacuum heat insulating material 11 has an excellent heat insulating performance of 0.0014 W / mK at an average temperature of 24 ° C., and the compression strength ratio in the repeated compression test is less than 0.65. It was found that the thermal conductivity was reduced by 0.0005 W / mK as compared with a vacuum heat insulating material in which a core material was formed from a laminate of short glass fibers.

  Further, compared to the case of Embodiment 1 in which a laminated body of short glass fibers is formed into a board shape by thermoforming, vacuum insulation is used although the compression strength ratio in the repeated compression test of the laminated body is equivalent. The insulation performance of the material was further improved.

Similarly, the core material density required to make the vacuum heat insulating material 11 10 mm thick has been 235 kg / m ³ in the present embodiment, which was conventionally 250 kg / m ³ .

  The reason why such a result was obtained is that the compression strength ratio in the repeated compression test of the laminate is 0.80, so that the fiber is bent or broken even when compressed by atmospheric pressure as compared with the conventional product. This is considered to be because the voids formed by the entanglement of the fibers are not easily generated and the atmospheric pressure can be maintained with a smaller number of contact points of the fibers.

  As a result, since the amount of heat transfer in the thickness direction of the core material is reduced, the heat insulating performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced. Therefore, in this Embodiment, since the usage-amount of glass wool can be reduced 6%, reduction of raw material cost is also realizable.

(Embodiment 3)
FIG. 3 shows a schematic plan view of a vacuum heat insulating material in Embodiment 3 of the present invention. FIG. 4 is a schematic cross-sectional view of the vacuum heat insulating material taken along line AA ′ of FIG.

  In FIG. 3, a vacuum heat insulating material 31 is formed by sealing a plurality of core materials 32 with a gas barrier outer covering material 33 under reduced pressure, and the core materials 32 are held in independent vacuum spaces by shaded heat welding portions 34. Has been.

  The manufacturing method of the vacuum heat insulating material 31 first installs a pair of upper and lower laminated films facing each other in the vacuum chamber. At this time, a plurality of core materials 32 dried at 140 ° C. for 20 minutes are fixed to the upper side surface of the lower laminate film by a known method such as heat welding in advance. Thereafter, the pressure is reduced so that the periphery of the core material 32 becomes 10 Pa or less, and the upper and lower laminated films that have been heated in advance are heat-welded including the core material 32 part, so that the plurality of core materials 32 are each core material. Laminate films facing to the vicinity of the periphery of 32 are thermally welded to form a thermally welded portion 34, and the core members 32 are held in independent vacuum spaces.

  In addition, the vacuum heat insulating material 31 in this Embodiment 3 is the same as that of the material structure demonstrated in Embodiment 1 except the manufacturing method of the vacuum heat insulating material 31 differing. However, a moisture adsorbent is used for the vacuum heat insulating material 31, and the thickness of the core material 32 part of the vacuum heat insulating material 31 is adjusted to 5 mm.

  The short glass fibers applied to the core material 32 were glass wool having an average fiber diameter of 3.5 μm, and the compression strength ratio in the repeated compression test of the laminate was 0.76.

  About the vacuum heat insulating material 31 produced in this way, the core part part thermal conductivity was measured with the auto-lambda made from Eihiro Seiki. As a result, the core part thermal conductivity of the vacuum heat insulating material 31 has an excellent heat insulating performance of 0.0015 W / mK at an average temperature of 24 ° C., and the compression strength ratio in the repeated compression test is less than 0.65. It was found that the thermal conductivity was reduced by 0.0004 W / mK as compared with a conventional vacuum heat insulating material in which a core material was formed from a laminate of short glass fibers.

Similarly, the core material density required to make the vacuum heat insulating material 31 5 mm thick is conventionally 250 kg / m ³ , but 240 kg / m ³ in the present embodiment.

  The reason why such a result was obtained is that the compression strength ratio in the repeated compression test of the laminate is 0.76, so that the fiber is bent or broken even when compressed by atmospheric pressure as compared with the conventional product. This is considered to be because the voids formed by the entanglement of the fibers are not easily generated and the atmospheric pressure can be maintained with a smaller number of contact points of the fibers.

  As a result, the amount of heat transfer in the thickness direction of the core material 32 is reduced, so that the heat insulating performance of the vacuum heat insulating material 31 is improved. Furthermore, since the compression resistance of the core material 32 is improved, the porosity of the core material 32 can be increased and the density of the core material 32 can be reduced. Therefore, in this Embodiment, since the usage-amount of glass wool can be reduced 4%, reduction of raw material cost is also realizable.

  Hereinafter, the characteristics in the repeated compression test of the short glass fibers constituting the core material of the vacuum heat insulating material of the present invention will be described in detail using examples and comparative examples, but the present invention is limited only to the examples. Is not to be done.

  (Table 1) When the glass reinforcing method of the short glass fiber used for the core material and the glass composition are variously changed, the compression strength ratio and the thickness ratio in the repeated compression test, and the thermal conductivity of the vacuum heat insulating material The relationship with the density is shown in Examples 1 to 6 and Comparative Example 1 or 2.

真空断熱材は、基本的に、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１の芯材２を構成するガラス短繊維のガラス強化方法を種々変化させて作製している。

The vacuum heat insulating material is basically manufactured by the same method as in the first embodiment, but is manufactured by changing the glass reinforcing method of the short glass fiber constituting the core material 2 of the vacuum heat insulating material 1 in various ways. Yes.

  Moreover, the glass composition is evaluated with three compositions of A to C. A is soda lime glass (C glass), B is alkali-free glass (E glass), and C is twice the alkali content in soda lime glass. In addition, 5 mol% of barium oxide was added. Note that C reduces the amount of silicon oxide by the increased amount of alkali and barium oxide.

  Furthermore, about soda-lime glass, the glass is tempered by the heating rapid cooling method, hydrofluoric acid treatment, and the ion exchange method.

  On the other hand, the compression strength ratio and the thickness ratio in the repeated compression test are shown as average values of n = 3, respectively, using an autograph manufactured by Shimadzu Corporation. At this time, the compression strength ratio is a value obtained by dividing the second compression strength at the reference thickness by the compression strength of 300 hPa, and the thickness ratio is the thickness at 300 hPa at the second compression and the thickness at 300 hPa at the first compression. The value divided by (reference thickness) is applied. The thermal conductivity was measured at an average temperature of 24 ° C. using an auto lambda manufactured by Eihiro Seiki.

Example 1
As the short glass fibers constituting the laminate applied to the core material, soda-lime glass mainly composed of general-purpose glass cullet is applied. However, since the short glass fiber is reinforced by the heating and quenching method, it has high strength and low brittleness.

  At this time, the air temperature during rapid cooling was set to 30 ° C.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.65, and the thickness ratio was 0.905.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0016 W / mK, an improvement of 0.0003 W / mK compared to the conventional product. Similarly, the core density of the vacuum heat insulating material is 245 kg / m ³ , which is 2% lower than the conventional 250 kg / m ³ .

  The reason why such a result was obtained is that the compressive strength ratio when the laminate constituting the core material is repeatedly subjected to the compression test is 0.65, and similarly the thickness ratio is 0.905. Compared to products, even when compressed by atmospheric pressure, the fiber is less likely to be bent or broken, and the void formed by the entanglement of the fiber is retained, enabling the atmospheric pressure to be maintained with fewer fiber contact points. I think because it became.

  As a result, since the amount of heat transfer in the thickness direction of the core material is reduced, the heat insulating performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced.

(Example 2)
As the short glass fibers constituting the laminate applied to the core material, soda-lime glass mainly composed of general-purpose glass cullet is applied. However, since the short glass fiber is reinforced by the heating and quenching method, it has high strength and low brittleness.

  At this time, the air temperature during rapid cooling was set to 30 ° C.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.75, and the thickness ratio was 0.915 as well.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0015 W / mK, an improvement of 0.0004 W / mK compared to the conventional product. Similarly, the core density of the vacuum heat insulating material is 240 kg / m ³ , which is conventionally 4% lower than that of 250 kg / m ³ .

  The reason why such a result was obtained is that the compression strength ratio when the laminate constituting the core material is repeatedly subjected to the compression test is 0.75, and similarly the thickness ratio is 0.915. Compared to products, even when compressed by atmospheric pressure, the fiber is less likely to be bent or broken, and the void formed by the entanglement of the fiber is retained, enabling the atmospheric pressure to be maintained with fewer fiber contact points. I think because it became.

  As a result, since the amount of heat transfer in the thickness direction of the core material is reduced, the heat insulating performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced.

(Example 3)
As the short glass fibers constituting the laminate applied to the core material, soda-lime glass mainly composed of general-purpose glass cullet is applied. However, since the short glass fiber is reinforced by the heating and quenching method, it has high strength and low brittleness.

  At this time, the air temperature during the rapid cooling was reduced from 30 ° C. to 10 ° C.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.84, and the thickness ratio was 0.930. The reason why the compressive strength ratio and the thickness ratio are increased in this way is considered to be that the quenching effect is more prominent by reducing the air temperature during quenching from 30 ° C. to 10 ° C.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0015 W / mK, an improvement of 0.0004 W / mK compared to the conventional product. Similarly, the core density of the vacuum heat insulating material is 240 kg / m ³ , which is conventionally 4% lower than that of 250 kg / m ³ .

  The above results are considered to be improved by the same action as in Example 1.

Example 4
As the short glass fibers constituting the laminate applied to the core material, soda-lime glass mainly composed of general-purpose glass cullet is applied. However, since the short glass fiber is reinforced by hydrofluoric acid treatment, it has high strength and low brittleness.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.85, and the thickness ratio was 0.931 in the same manner. These values were almost the same as those at the time of quenching at an air temperature of 10 ° C. in the heating and quenching method.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0014 W / mK, an improvement of 0.0005 W / mK compared to the conventional product. Similarly, the core density of the vacuum heat insulating material is 240 kg / m ³ , which is conventionally 4% lower than that of 250 kg / m ³ .

  The above results are considered to be improved by the same action as in Example 1.

(Example 5)
As the short glass fibers constituting the laminate applied to the core material, soda-lime glass mainly composed of general-purpose glass cullet is applied. However, since the short glass fiber is reinforced by ion exchange treatment, it has high strength and low brittleness.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.90, and the thickness ratio was 0.942. These values are increased as compared with the heating and quenching method, and the ion exchange treatment is considered to be more effective.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0014 W / mK, an improvement of 0.0005 W / mK compared to the conventional product. Similarly, the core density of the vacuum heat insulating material is 240 kg / m ³ , which is conventionally 4% lower than that of 250 kg / m ³ .

  The above results are considered to be improved by the same action as in Example 1.

(Example 6)
The E glass which is an alkali free glass is applied to the glass short fiber which comprises the laminated body applied to a core material. E glass has a Young's modulus of the glass composition itself about 10% larger than that of soda lime glass. As a result, the tensile strength of the fiber is increasing.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.80, and the thickness ratio was 0.930.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0014 W / mK, an improvement of 0.0005 W / mK compared to the conventional product. Similarly, the core density of the vacuum heat insulating material is 235 kg / m ³ , which is conventionally reduced by 6% compared to 250 kg / m ³ .

  Although the above result is considered to be improved by the same action as in Example 1, it can be seen that the heat insulation performance can be improved by changing the glass composition.

(Comparative Example 1)
A general soda-lime glass is applied as the glass short fiber to the glass composition forming the short glass fiber of the fibrous material applied to the core material. Similarly, since the glass fiber is not specially treated, it is a conventional short glass fiber having general-purpose material properties.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.63, and the thickness ratio was similarly 0.895.

At this time, the heat conductivity of the vacuum heat insulating material was 0.0019 W / mK, and the core material density of the vacuum heat insulating material was 250 kg / m ³ .

(Comparative Example 2)
The glass composition forming the short glass fibers of the fibrous material applied to the core material is a soda-lime glass that doubles the alkali content and is added with 5 mol% of barium oxide. Note that the amount of silicon oxide is reduced by the amount of increase in alkali and barium oxide.

  The glass fiber was fiberized by a general method without any special treatment.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.50, and the thickness ratio was 0.880.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0022 W / mK, which was 0.0003 W / mK worse than the conventional product. Similarly, the density of the core material of the vacuum heat insulating material was 280 kg / m ³ , which was increased as compared with the conventional 250 kg / m ³ .

  As mentioned above, since the vacuum heat insulating material concerning this invention has the outstanding heat insulation performance, high heat insulation performance is obtained by thinner thickness. Therefore, in addition to uses such as a refrigerator and a cooler box, the present invention can be applied to uses that require high heat insulation performance in a narrow space such as a liquid crystal projector, a copy machine, and a notebook computer.

Sectional schematic diagram of the vacuum heat insulating material in Embodiment 1 of this invention Sectional schematic diagram of the vacuum heat insulating material in Embodiment 2 of this invention Plane schematic diagram of the vacuum heat insulating material in Embodiment 3 of this invention Cross-sectional schematic diagram of the vacuum heat insulating material along the A-A 'line in FIG. Cross-sectional view of a conventional vacuum insulation core

Explanation of symbols

1,31 Vacuum insulation material 2,32 Core material 3,33 Jacket material

The present invention relates to a method for manufacturing a vacuum heat insulating material in which a core material is covered with a jacket material and the inside is sealed under reduced pressure, and a vacuum heat insulating material manufactured by the manufacturing method .

  As the core material used for the vacuum heat insulating material, an inorganic compound having a low thermal conductivity and a low gas generation is suitable. In particular, a vacuum heat insulating material using a glass fiber laminate as a core material is known to have excellent heat insulating performance, and is shown in FIG. 5 as an example of a core material constituting the vacuum heat insulating material. There is.

  FIG. 5 shows that the inorganic fine fibers 91a are randomly laminated so that the length direction thereof is perpendicular to the heat transfer direction and the length directions of the inorganic fine fibers 91a intersect each other. It is provided with a penetration fiber 91b that forms a high-density inorganic fine fiber mat 9 by being driven into contact with the laminated thin fiber 91a in parallel with the heat transfer direction. It has been proposed to form a core material by superimposing sheets (N sheets) (see, for example, Patent Document 1).

  In the conventional vacuum heat insulating material configured as described above, since the inorganic small-diameter fibers 91a are arranged randomly and perpendicularly to the heat transfer direction, the fibers 91a are in point contact with each other. The contact heat resistance at the contact point is large, and the heat transfer amount in the core thickness direction is small.

  However, only the fiber 91a arranged perpendicular to the heat transfer direction reduces the compression resistance against atmospheric pressure acting in the heat transfer direction, and the core material is compressed by the atmospheric pressure acting after vacuum packaging, making it difficult to ensure thickness. Become.

Therefore, the penetration fibers 91b are partially arranged in parallel with the heat transfer direction. However, since the heat insulation performance is lowered by the penetration fibers 91b, a core material is formed by superimposing a plurality of (N) inorganic thin fiber mats 9, and the amount of heat transferred by the penetration fibers 91b is reduced.
Japanese Examined Patent Publication No. 7-103955

  However, in the above conventional configuration, even if the core material is formed by superimposing a plurality of (N) inorganic thin fiber mats 9 and the amount of heat transfer by the penetration fibers 91b is reduced, it is arranged in parallel to the heat transfer direction. Since the penetration fibers 91b, that is, the fibers 91b themselves act as heat bridges that directly transfer heat, it is difficult to reduce the amount of heat transfer. Moreover, since the heat | fever conducts with the heat conductivity intrinsic | native to glass material in the fiber 91b arrange | positioned in parallel with the heat transfer direction, the amount of heat transfer increases in proportion to the number of fibers arrange | positioned in parallel with the heat transfer direction.

  Therefore, the subject that the heat insulation performance of the vacuum heat insulating material deteriorated in proportion to the quantity of the glass fiber 91b arrange | positioned in parallel with the heat-transfer direction occurred.

  On the other hand, in the core material comprised only of the glass fiber 91a arrange | positioned substantially perpendicular | vertical with respect to the heat transfer direction, there existed a subject that the heat insulation performance of a vacuum heat insulating material deteriorated for the following reason.

  When the glass fiber constituting the core material does not have sufficient strength, the fiber constituting the core material is bent or broken by atmospheric pressure. When the bending of the fibers proceeds, the void portion of the core material formed by the entanglement between the fibers is crushed, and the number of contact points between the fibers increases. As a result, the number of heat transfer paths increases and, in part, the contact area increases due to contact of the fibers from point contact to line contact, etc., so the contact thermal resistance decreases.

  In addition, when the fiber breaks, as in the case where the bending of the fiber proceeds, the void portion of the core material formed by the entanglement between the fibers is crushed, and the number of contact points between the fibers increases. Specifically, the contact thermal resistance decreases because the contact area increases, for example, where the fiber comes into contact with line contact. Furthermore, the void portion of the core material formed by the entanglement between the fibers is filled with the broken fiber, the void of the core material is further reduced, and the number of contact points of the fiber is also increased.

  For this reason, the amount of heat transfer is increased, the heat insulation performance of the vacuum heat insulating material is reduced, and the thickness of the core material cannot be secured, and the amount of the fibrous substance constituting the core material needs to be increased. There was a problem that the material cost increased.

The present invention solves the above-described conventional problems, and provides a method for producing a vacuum heat insulating material that can further improve the heat insulating performance, improve the compression resistance of the core material, and reduce the material cost for the core material. For the purpose.

To achieve the above object, the manufacturing method of the vacuum heat insulating material of the present invention, Ri greens and vacuum inside said outer covering material covering the core material made of a laminate of the glass wool in the enveloping member, the short glass A glass wool having an average fiber diameter of 3 to 5 μm made of soda-lime glass is used as the fiber, and the length of the short glass fiber is such that the length direction of the short glass fiber is substantially perpendicular to the heat transfer direction. In the manufacturing method of the vacuum heat insulating material which comprises the said laminated body by arrange | positioning at random so that a direction may mutually cross | intersect and laminating | stacking on the thickness direction of the said core material , it compresses rapidly after compressing the said laminated body to 1013 hPa. In the case of repeating the operation of releasing the pressure, the thickness of the laminate when the compression strength is 300 hPa at the first compression is set as the reference thickness, and the compression strength at the reference thickness at the second compression is 30. As the ratio of the hPa is 0.65 or more, in advance, with respect to the short glass fibers, the glass wool performs a process of a low brittleness, and high strength.

When the inventor of the present invention performs a process for making the short glass fiber low brittle and high in strength to the short glass fiber, the length direction of the short glass fiber is substantially perpendicular to the heat transfer direction. laminate constituted by the and the length direction of the short glass fibers to be laminated by placing at random so as to intersect each other, a reduction in compressive strength at the reference thickness with time repeated compression is rather small Thus, it was found that the heat insulating performance of the vacuum heat insulating material is improved by applying this laminate to the core material of the vacuum heat insulating material.

  As a result, the short glass fibers constituting the laminate are low in brittleness and strong in fiber strength. Therefore, even when compressed by atmospheric pressure, the fibers are not easily bent or broken, and voids formed by entanglement of fibers. Is retained. In addition, since the fiber itself is difficult to break, the original fiber length is long since the fiber was manufactured.

The thickness of the resulting, the core arranged randomly such that the length direction of and the short glass fibers to the glass wool its longitudinal direction is substantially perpendicular to the heat transfer directions cross each other Even in a laminate with a structure laminated in the direction, glass short fibers can maintain atmospheric pressure with a smaller number of contact points between the fibers because of the same action as a leaf spring, and heat transfer in the thickness direction of the core material The number of routes is reduced.

Further, the thickness direction of the glass wool is the core length direction of and the short glass fibers as its longitudinal direction is substantially perpendicular to the heat transfer direction is disposed randomly so as to intersect with each other However, since the fiber length of this short glass fiber is longer than that of the conventional product, the laminated state is further improved and the heat transfer distance in the core material thickness direction is increased. .

  For the above reason, since the heat transfer amount in the thickness direction of the core material decreases, the heat insulating performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, the core material can be reduced in density, and at the same time, a vacuum heat insulating material that realizes cost reduction of the core material is provided. be able to.

The manufacturing method of vacuum insulation material of another aspect of the present invention, glass wool Ri name a core material made of laminate covered by envelope material to reduce the internal pressure said outer covering material of soda as the glass wool Glass wool having an average fiber diameter of 3 to 5 μm made of lime glass is used, and the short directions of the short glass fibers are substantially perpendicular to the heat transfer direction and the length directions of the short glass fibers are mutually In the method for manufacturing a vacuum heat insulating material in which the laminated body is configured by randomly arranging and laminating in the thickness direction of the core material, the compressed body is quickly released after being compressed to 1013 hPa. In the case of repeating the operation, the thickness of the laminate when the compressive strength is 300 hPa at the first compression and the thickness of the laminate when the compressive strength is 300 hPa at the second compression, As the ratio of the reference thickness of 0.9 or more, in advance, with respect to the short glass fibers, the glass wool performs a process of a low brittleness, and high strength.

  In this invention as well, the heat insulation performance of the vacuum heat insulating material is improved because the amount of heat transfer in the thickness direction of the core material is reduced by the same action as the previous invention.

  Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced. As a result, it is possible to provide a vacuum heat insulating material that realizes cost reduction of the core material.

  Moreover, like the previous invention, management can be easily performed by substituting the compression characteristics in the laminated body of short glass fibers, and the entire image of the laminated body can be easily grasped more specifically.

In the vacuum heat insulating material manufactured by the method for manufacturing a vacuum heat insulating material of the present invention, the heat transfer performance in the thickness direction of the core material is reduced, so that the heat insulating performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material is increased, and the density of the core material can be reduced. Therefore, it is possible to provide a vacuum heat insulating material that realizes high performance and cost reduction of the core material.

The average fiber The invention according to claim 1, comprising a core material consisting of a laminate of glass wool outer Ri Na and covered with a covering material to reduce the internal pressure said outer covering material, soda lime glass as the glass wool Glass wool with a diameter of 3 to 5 μm is used, and the short glass fibers are randomly selected so that the length direction of the short glass fibers is substantially perpendicular to the heat transfer direction and the length directions of the short glass fibers intersect each other. In the method for manufacturing a vacuum heat insulating material configured by stacking in the thickness direction of the core material and repeating the operation of quickly releasing the compression after compressing the laminate to 1013 hPa, The thickness of the laminate when the compressive strength is 300 hPa at the time of the first compression is a reference thickness, and the ratio of the compressive strength at the reference thickness at the time of the second compression to 300 hPa is 0.65 or more. As previously, with respect to the short glass fibers, a method for producing a vacuum insulation material, which comprises carrying out the process of the short glass fibers and low brittleness and high strength.

  In general, the destruction of the glass composition is a typical brittle fracture from a low temperature to a normal temperature, and the fracture occurs rapidly under a critical stress. Such fracture of a brittle solid occurs when the bonds between atoms are broken by the tensile stress and the atoms are separated.

  However, since there are actually flaws called large and small Griffith flows on the surface and inside of the glass, these become stress concentration sources, and breakage occurs under load stress much lower than the theoretical value. This is one of the causes of glass brittleness.

  Even in the case of a short glass fiber, the fiber is less likely to break against a load stress such as compression by reinforcing the fiber and making the glass itself low brittle. As a result, the laminate is less reduced in compressive strength at the reference thickness during repeated compression.

  Therefore, even in a vacuum heat insulating material in which a core material composed of a laminate of short glass fibers is covered with an outer cover material and the inside is decompressed, the fibers constituting the core material by compressing the core material by atmospheric pressure after vacuum packaging Even when a tensile stress is applied to the fiber, the fiber is not easily broken, and the voids of the core material formed by the entanglement of the fiber are maintained. This means that the core material shape can be maintained against the atmospheric pressure with a smaller number of fiber contact points, and the number of heat transfer paths in the core material thickness direction is reduced. Become.

  Thus, by applying the short glass fiber having low brittleness and high fiber strength to the core material, the heat transfer performance in the thickness direction of the core material is reduced, so that the heat insulation performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and at the same time, the density of the core material can be reduced. As a result, it is possible to provide a vacuum heat insulating material that realizes cost reduction of the core material.

  Further, when the glass short fiber laminate is repeatedly compressed, the glass short fiber laminate is vacuumed so that the ratio of the compression strength at the reference thickness at the second compression to 300 hPa is 0.65 or more. Since the heat transfer amount in the thickness direction of the core material is reduced by using the core material of the heat insulating material, the heat insulating performance of the vacuum heat insulating material is improved.

  Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced. As a result, it is possible to provide a vacuum heat insulating material that realizes cost reduction of the core material.

  Moreover, it is essential to manage the brittle characteristics of short glass fibers by the tensile strength of the fibers. However, in practice, the short glass fibers constituting the laminate have a wide distribution in the fiber strength, and therefore the measurement required to grasp the overall image of the short glass fibers requires a great deal of labor. Therefore, as shown in the present invention, management can be easily performed by substituting the compression characteristics of the short glass fiber laminate, and the overall image of the laminate can be more easily grasped.

  In short, it has been newly found that the repeated compressive strength ratio obtained by this test method has a good correlation with the thermal conductivity of the vacuum heat insulating material.

  On the other hand, the amount of compression at the time of repeated compression is set to 1013 hPa in terms of compressive strength is set because the vacuum heat insulating material in which the laminated body is vacuum-packed is constantly subjected to atmospheric pressure, but it is a problem that it slightly varies Absent. However, when the pressure is increased to about twice the atmospheric pressure, the fiber breaks even in the case of low brittleness or high strength fiber, so the compressive strength at the reference thickness at the second compression and 300 hPa Since the ratio may be less than 0.65, the compression strength during repeated compression is desirably 1013 hPa.

  Moreover, the reference thickness at the time of repeated compression is the thickness of the laminate at 300 hPa. The compression strength ratio at the time of repeated compression varies depending on the compression strength as the reference thickness, but the laminate at 300 hPa This is because the correlation with the heat insulating performance of the vacuum heat insulating material becomes clear when the thickness is used as a reference.

  The compression strength ratio in the repeated compression test is a value obtained by dividing the second compression strength at the reference thickness by 300 hPa that sets the reference thickness.

The average fiber The invention according to claim 2, comprising a core material consisting of a laminate of glass wool outer Ri Na and covered with a covering material to reduce the internal pressure said outer covering material, soda lime glass as the glass wool Glass wool with a diameter of 3 to 5 μm is used, and the short glass fibers are randomly selected so that the length direction of the short glass fibers is substantially perpendicular to the heat transfer direction and the length directions of the short glass fibers intersect each other. In the method for manufacturing a vacuum heat insulating material configured by stacking in the thickness direction of the core material and repeating the operation of quickly releasing the compression after compressing the laminate to 1013 hPa, The thickness of the laminate when the compressive strength is 300 hPa during the first compression is a reference thickness, and the ratio of the thickness of the laminate when the compressive strength is 300 hPa during the second compression and the reference thickness is As a .9 or more, in advance, with respect to the short glass fibers, a method for producing a vacuum insulation material and performing the processing of the short glass fibers and low brittleness and high strength.

  When the laminate of short glass fibers is repeatedly compressed, the short glass fibers have a ratio of 0.9 or more to the thickness of the laminate when the compressive strength is 300 hPa during the second compression. By using the laminated body as the core material of the vacuum heat insulating material, the heat transfer performance in the thickness direction of the core material is reduced by the same action as the invention of claim 1, so the heat insulating performance of the vacuum heat insulating material is improved. To do.

  Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced. As a result, it is possible to provide a vacuum heat insulating material that realizes cost reduction of the core material.

  As in the first aspect of the invention, management can be easily performed by substituting the compression characteristics of the short glass fiber laminate, and the overall image of the laminate can be more easily grasped.

  In addition, when the laminated body of short glass fibers is formed into a board shape by binder or thermoforming, the heat transfer amount in the thickness direction of the core material is reduced, so that the heat insulating performance of the vacuum heat insulating material is improved.

  Further, since the compression resistance of the core material is improved, the porosity of the core material can be increased and the density of the core material can be reduced. As a result, it is possible to provide a vacuum heat insulating material that realizes cost reduction of the core material.

  Furthermore, when the short glass fiber laminate is formed into a board by binder or thermoforming, the bulk of the laminate can be reduced and the board is given rigidity, so when the board size is large However, its handling is greatly improved.

  In addition, also when it uses as a core material without shape | molding the laminated body of a glass short fiber in board shape, since the heat transfer amount of the thickness direction of a core material falls, the heat insulation performance of a vacuum heat insulating material improves.

  Further, since the compression resistance of the core material is improved, the porosity of the core material can be increased and the density of the core material can be reduced. As a result, it is possible to provide a vacuum heat insulating material that realizes cost reduction of the core material.

  Moreover, if the laminated body of short glass fibers is applied as a core material without forming into a board shape, the load stress on the short glass fibers constituting the laminated body becomes smaller, and the progress of breakage of the short glass fibers is most suppressed. Therefore, more excellent heat insulation performance can be realized in the vacuum heat insulating material.

  Thus, the glass short fiber applied as a core material of a vacuum heat insulating material can improve the heat insulation performance of a vacuum heat insulating material, so that it is low brittle and the fiber strength is large. Moreover, the density reduction of a vacuum heat insulating material is realizable, so that the fiber strength is large.

  It is essential to control the brittle properties of short glass fibers by the tensile strength of the fibers. However, in practice, the short glass fibers have a wide distribution of fiber strength, and the measurement required to grasp the overall image of the short glass fibers requires a great deal of labor. Therefore, as shown in the present invention, it is desirable to manage by substituting the compression characteristics in the laminated body of short glass fibers.

  Thus, in order to improve the thermal conductivity of the vacuum heat insulating material, it is desirable that the reduction in the compressive strength at the reference thickness during repeated compression is small in the operation of repeatedly compressing and releasing the glass short fiber laminate.

The invention according to claim 3 is the invention according to claim 1 or 2, wherein the short glass fiber has a low brittleness and a high strength, and the short glass fiber has a high temperature short glass immediately after fiberization. Heating and quenching method in which cooling air is blown against the fiber, hydrofluoric acid treatment to remove the Griffith flow existing on the glass surface of the short glass fiber with hydrofluoric acid, and sodium ions on the glass surface of the short glass fiber with a molecular diameter This is a method for producing a vacuum heat insulating material characterized in that it is based on any one of the ion exchange methods of replacing with large potassium ions, and is a heating and quenching method in which cooling air is blown against high-temperature short glass fibers immediately after fiberization. Hydrofluoric acid treatment to remove the Griffith flow existing on the glass surface of the short glass fiber with hydrofluoric acid, and sodium ion on the glass surface of the short glass fiber The by adopting any of the ion exchange method to replace a large potassium ions molecular diameter, it is possible to short glass fibers with low brittleness and high strength.

Invention of Claim 4 is the vacuum heat insulating material manufactured by the manufacturing method of the vacuum heat insulating material as described in any one of Claim 1 to 3.

  Hereinafter, the test method for obtaining the repeated compressive strength ratio of the present invention will be specifically described.

  (1) As a pretreatment of the test sample, in order to remove the compression history of the sample due to vacuum packaging or packing, the sample is first compressed to 300 hPa.

  (2) As the first compression, the test sample is compressed to 1013 hPa and quickly released to a predetermined thickness. The thickness at which the compression strength becomes 300 hPa in this compression process is taken as the reference thickness.

  (3) The same compression as the first compression is performed again until the second compression to 1013 hPa. In this compression process, the compressive strength at the reference thickness is measured.

  (4) The repeated compression strength ratio is calculated from the following equation.

Repeated compressive strength ratio = compressive strength at the standard thickness during the second compression / 300 hPa
At this time, a general autograph can be used as the repeated compression test apparatus. As an example of the test conditions, the compression speed is 10 mm / min, the compression jig is an iron circular shape having a diameter of 100 mm both in the upper and lower sides, the test sample is 200 mm × 200 mm in size, and the basis weight is 2500 g / m ² ± 15%. The center part of the sample is compressed and the compressive strength test is repeatedly performed.

  As the short glass fiber that can be used in the present invention, a known fiber can be used, but it is desirable that the fiber diameter is small and the thermal conductivity of the material is small, and the tensile strength of the fiber is 0.5 GPa or more. It is more desirable.

In addition, the laminate is randomly arranged so that the short glass fibers are substantially perpendicular to the heat transfer direction (thickness direction) in the length direction, and the length directions of the short glass fibers intersect each other. In addition, a laminate of webs formed so that the fibers are in point contact with each other is desirable. Further, the laminate formed by laminating the webs is more preferably a laminate in which the webs are joined by minimum entanglement of fibers capable of maintaining the integrity of the laminate, and are uniformly laminated in the thickness direction. is there. By setting it as such a laminated body, the contact heat resistance between fibers becomes more dominant than the heat conductivity intrinsic | native to a glass composition in the heat transfer amount of a core material thickness direction.

As an example, the thermal conductivity of the general-purpose glass composition at room temperature is around 1 W / mK, and the short glass fibers are arranged so that the length direction thereof is substantially perpendicular to the heat transfer direction , and the short glass fibers are used. In the case of a vacuum heat insulating material having a core of a laminate in which the length directions of the layers are randomly arranged so as to cross each other , that is, a laminate in which webs are laminated, the apparent heat related to the solid component of the laminate The conductivity is 1/100 or less of the glass composition itself.

  The fiber diameter is not particularly specified, but finer fiber diameter can provide better heat insulation performance. However, it is desirable to use one having an average fiber diameter of 3 to 5 μm from the viewpoint of economy.

  On the other hand, an example of a method for making short glass fibers low brittle and high in strength is as follows.

  The short glass fiber applicable to the present invention can make the short glass fiber low brittle and high in strength by optimizing the glass composition and the manufacturing process. Among these, methods for increasing the strength of short glass fibers by optimizing the manufacturing process include a method called a chemical strengthening method or an ion exchange method, and a method called a heating rapid cooling method or an air cooling strengthening method.

  The chemical strengthening method is a method in which the glass surface is eroded with hydrofluoric acid or the like, and thereby the Griffith flow existing on the glass surface can be removed, so that the brittleness and strength of the short glass fiber can be improved.

  In addition, the ion exchange method is a method in which a high compressive stress layer is applied to the glass surface in advance by replacing sodium ions on the glass surface with potassium ions having a large molecular diameter. Similarly, the brittleness and strength of the glass are improved. it can.

However, the heating and cooling method is most used industrially. This is processed by spraying low-temperature air on heated glass, and by applying a high compressive stress layer to the surface of the glass in advance, durability against tensile stress is improved. This method can be similarly applied to glass fibers, and glass fibers are reinforced by blowing cooling air on high-temperature fibers immediately after fiberization, so that the glass fibers can be efficiently processed.

  As mentioned above, although the glass strengthening method utilized industrially was shown, the method of strengthening the mechanical strength of glass fiber is not limited to what was mentioned above, A well-known method is applicable.

  On the other hand, it is more desirable that the laminate film forming the covering material that can be used in the present invention is composed of a plastic film having at least one of a metal foil layer and a vapor deposition layer in order to impart high gas barrier properties. At this time, a known material can be used for the metal foil layer and the vapor deposition layer, and is not particularly specified.

  In addition, the lamination film is preferably formed by a dry lamination method using an adhesive for dry lamination, but an extrusion lamination method in which a part of the laminate film is melt extruded using an olefin resin is applied. Also good.

  Hereinafter, embodiments 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 schematic cross-sectional view of a vacuum heat insulating material in Embodiment 1 of the present invention.

  In FIG. 1, the vacuum heat insulating material 1 is configured by inserting a core material 2 and an adsorbent 4 into an outer cover material 3 and reducing the pressure inside. At this time, the core material 2 is adjusted so that the vacuum heat insulating material has a thickness of 10 mm.

  The vacuum heat insulating material 1 is prepared by drying the core material 2 in a drying furnace at 140 ° C. for 20 minutes, and then inserting the three sides of the laminate film into the envelope material 3 formed into a bag shape by heat sealing. The pressure inside the jacket 3 is reduced to 10 Pa or less, and the opening is hermetically sealed by heat welding.

  On the other hand, the glass short fiber applied to the core material 2 is glass wool having an average fiber diameter of 3.5 μm. However, the glass wool uses a general-purpose soda-lime glass composition, but immediately after fiberization, the glass wool is rapidly cooled by blowing cooling air to reinforce the fibers.

  The core material 2 is produced by laminating glass wool made of short glass fiber webs to a predetermined thickness, and molding a laminated body in which the webs are joined by entanglement. Then, the board-shaped core material is shape | molded by thermoforming the laminated body of a short glass fiber with a hot press at 450 degreeC lower than the distortion point of glass for 5 minutes.

  In addition to the above method, a board-like core material having higher rigidity can be formed by applying a binder during hot pressing. These can be determined in consideration of the required quality and productivity of the vacuum heat insulating material.

  The jacket material 3 is composed of a plastic laminate film in which a polyethylene terephthalate film (12 μm) is applied to the outermost layer, an aluminum foil (6 μm) is applied to the intermediate layer, and a linear low density polyethylene film (50 μm) is applied to the heat-welded layer. .

  The adsorbent 4 uses calcium oxide as a moisture adsorbent.

  About the vacuum heat insulating material 1 produced in this way, the thermal conductivity was measured with an auto lambda manufactured by Eihiro Seiki. As a result, the heat conductivity of the vacuum heat insulating material 1 has an excellent heat insulating performance of 0.0015 W / mK at an average temperature of 24 ° C., and the compression strength ratio in the repeated compression test of the laminate is 0.8. there were.

  This means that the thermal conductivity is reduced by 0.0004 W / mK compared to a vacuum heat insulating material in which a core material is formed from a laminate of conventional short glass fibers having a compression strength ratio of less than 0.65 in a repeated compression test. I understood.

Similarly, the core material density required to make the vacuum heat insulating material 1 10 mm thick is conventionally 250 kg / m ³ , but in the present embodiment it is 240 kg / m ³ .

  The reason why such a result was obtained is that the compression strength ratio in the repeated compression test of the laminate is 0.8, so even if the core material is compressed by atmospheric pressure compared to the conventional product, the bending of the fiber It is considered that breakage hardly occurs, voids formed by fiber entanglement are maintained, and atmospheric pressure can be maintained with a smaller number of fiber contact points.

  As a result, since the amount of heat transfer in the thickness direction of the core material is reduced, the heat insulating performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced. Therefore, in this Embodiment, since the usage-amount of glass wool can be reduced 4%, reduction of raw material cost is also realizable.

  In this embodiment, as the short glass fibers forming the core material, glass wool, which is a general-purpose industrial material, is applied, and the heating and quenching method is performed so that the compression strength ratio in the repeated compression test of the laminate is 0.65 or more. The fiber is reinforced and applied.

  However, the short glass fiber that can be applied to the core material can be applied without any particular problem as long as the short glass fiber has low brittleness and high strength. However, desirably, a laminate of short glass fibers having a compression strength ratio of 0.65 or more in a repeated compression test of the laminate, more desirably, a laminate of short glass fibers having a compression strength ratio of 0.70 or more, More preferably, it is a laminate of short glass fibers having a compressive strength ratio of 0.75 or more.

  In addition, although the compressive strength ratio greatly reduces the thermal conductivity at the boundary of 0.65, if the compressive strength ratio exceeds 0.75, no further decrease in the thermal conductivity can be confirmed. Therefore, when the compressive strength ratio is in the range of 0.65 or 0.75, the thermal conductivity tends to decrease as the compressive strength ratio increases.

  The repeated compression test was carried out using an iron circular jig having a diameter of 100 mm using an autograph made by Shimadzu Corporation. At this time, the compression speed was 10 mm / min. In addition, in order to unify the compression load history of the test material and suppress the test variation, this test was performed after the compression treatment was once performed as a pretreatment until the compression strength reached 300 hPa. The compressive strength ratio is shown as an average of n = 3.

(Embodiment 2)
FIG. 2 is a schematic cross-sectional view of the vacuum heat insulating material in Embodiment 2 of the present invention.

  In FIG. 2, the vacuum heat insulating material 11 is configured by inserting a core material 12 and an adsorbent 14 into an outer cover material 13 and reducing the pressure inside. At this time, the core material 12 is adjusted so that the vacuum heat insulating material has a thickness of 10 mm.

  The core material 2 was produced by laminating glass wool made of short glass fiber webs to a predetermined thickness, and molding a laminate in which the webs were joined by entanglement. At this time, the core material 12 is used as a core material without forming the laminated body into a board shape by binder or thermoforming.

  In addition, the vacuum heat insulating material 11 in this Embodiment 2 is the same as that of the material structure in 1st Embodiment, and a preparation method except the manufacturing method of the core material 12 differing.

  The short glass fibers applied to the core material 12 were glass wool having an average fiber diameter of 3.5 μm, and the compression strength ratio in the repeated compression test of the laminate was 0.80.

  About the vacuum heat insulating material 11 produced in this way, the thermal conductivity was measured with an auto lambda manufactured by Eihiro Seiki. As a result, the heat conductivity of the vacuum heat insulating material 11 has an excellent heat insulating performance of 0.0014 W / mK at an average temperature of 24 ° C., and the compression strength ratio in the repeated compression test is less than 0.65. It was found that the thermal conductivity was reduced by 0.0005 W / mK as compared with a vacuum heat insulating material in which a core material was formed from a laminate of short glass fibers.

  Further, compared to the case of Embodiment 1 in which a laminated body of short glass fibers is formed into a board shape by thermoforming, vacuum insulation is used although the compression strength ratio in the repeated compression test of the laminated body is equivalent. The insulation performance of the material was further improved.

Similarly, the core material density required to make the vacuum heat insulating material 11 10 mm thick has been 235 kg / m ³ in the present embodiment, which was conventionally 250 kg / m ³ .

  The reason why such a result was obtained is that the compression strength ratio in the repeated compression test of the laminate is 0.80, so that the fiber is bent or broken even when compressed by atmospheric pressure as compared with the conventional product. This is considered to be because the voids formed by the entanglement of the fibers are not easily generated and the atmospheric pressure can be maintained with a smaller number of contact points of the fibers.

  As a result, since the amount of heat transfer in the thickness direction of the core material is reduced, the heat insulating performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced. Therefore, in this Embodiment, since the usage-amount of glass wool can be reduced 6%, reduction of raw material cost is also realizable.

(Embodiment 3)
FIG. 3 shows a schematic plan view of a vacuum heat insulating material in Embodiment 3 of the present invention. FIG. 4 is a schematic cross-sectional view of the vacuum heat insulating material taken along line AA ′ of FIG.

  In FIG. 3, a vacuum heat insulating material 31 is formed by sealing a plurality of core materials 32 with a gas barrier outer covering material 33 under reduced pressure, and the core materials 32 are held in independent vacuum spaces by shaded heat welding portions 34. Has been.

  The manufacturing method of the vacuum heat insulating material 31 first installs a pair of upper and lower laminated films facing each other in the vacuum chamber. At this time, a plurality of core materials 32 dried at 140 ° C. for 20 minutes are fixed to the upper side surface of the lower laminate film by a known method such as heat welding in advance. Thereafter, the pressure is reduced so that the periphery of the core material 32 becomes 10 Pa or less, and the upper and lower laminated films that have been heated in advance are heat-welded including the core material 32 part, so that the plurality of core materials 32 are each core material. Laminate films facing to the vicinity of the periphery of 32 are thermally welded to form a thermally welded portion 34, and the core members 32 are held in independent vacuum spaces.

  In addition, the vacuum heat insulating material 31 in this Embodiment 3 is the same as that of the material structure demonstrated in Embodiment 1 except the manufacturing method of the vacuum heat insulating material 31 differing. However, a moisture adsorbent is used for the vacuum heat insulating material 31, and the thickness of the core material 32 part of the vacuum heat insulating material 31 is adjusted to 5 mm.

  The short glass fibers applied to the core material 32 were glass wool having an average fiber diameter of 3.5 μm, and the compression strength ratio in the repeated compression test of the laminate was 0.76.

  About the vacuum heat insulating material 31 produced in this way, the core part part thermal conductivity was measured with the auto-lambda made from Eihiro Seiki. As a result, the core part thermal conductivity of the vacuum heat insulating material 31 has an excellent heat insulating performance of 0.0015 W / mK at an average temperature of 24 ° C., and the compression strength ratio in the repeated compression test is less than 0.65. It was found that the thermal conductivity was reduced by 0.0004 W / mK as compared with a conventional vacuum heat insulating material in which a core material was formed from a laminate of short glass fibers.

Similarly, the core material density required to make the vacuum heat insulating material 31 5 mm thick is conventionally 250 kg / m ³ , but 240 kg / m ³ in the present embodiment.

  The reason why such a result was obtained is that the compression strength ratio in the repeated compression test of the laminate is 0.76, so that the fiber is bent or broken even when compressed by atmospheric pressure as compared with the conventional product. This is considered to be because the voids formed by the entanglement of the fibers are not easily generated and the atmospheric pressure can be maintained with a smaller number of contact points of the fibers.

  As a result, the amount of heat transfer in the thickness direction of the core material 32 is reduced, so that the heat insulating performance of the vacuum heat insulating material 31 is improved. Furthermore, since the compression resistance of the core material 32 is improved, the porosity of the core material 32 can be increased and the density of the core material 32 can be reduced. Therefore, in this Embodiment, since the usage-amount of glass wool can be reduced 4%, reduction of raw material cost is also realizable.

  Hereinafter, the characteristics in the repeated compression test of the short glass fibers constituting the core material of the vacuum heat insulating material of the present invention will be described in detail using examples and comparative examples, but the present invention is limited only to the examples. Is not to be done.

  (Table 1) When the glass reinforcing method of the short glass fiber used for the core material and the glass composition are variously changed, the compression strength ratio and the thickness ratio in the repeated compression test, and the thermal conductivity of the vacuum heat insulating material The relationship with the density is shown in Examples 1 to 6 and Comparative Example 1 or 2.

真空断熱材は、基本的に、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１の芯材２を構成するガラス短繊維のガラス強化方法を種々変化させて作製している。

The vacuum heat insulating material is basically manufactured by the same method as in the first embodiment, but is manufactured by changing the glass reinforcing method of the short glass fiber constituting the core material 2 of the vacuum heat insulating material 1 in various ways. Yes.

  Moreover, the glass composition is evaluated with three compositions of A to C. A is soda lime glass (C glass), B is alkali-free glass (E glass), and C is twice the alkali content in soda lime glass. In addition, 5 mol% of barium oxide was added. Note that C reduces the amount of silicon oxide by the increased amount of alkali and barium oxide.

  Furthermore, about soda-lime glass, the glass is tempered by the heating rapid cooling method, hydrofluoric acid treatment, and the ion exchange method.

  On the other hand, the compression strength ratio and the thickness ratio in the repeated compression test are shown as average values of n = 3, respectively, using an autograph manufactured by Shimadzu Corporation. At this time, the compression strength ratio is a value obtained by dividing the second compression strength at the reference thickness by the compression strength of 300 hPa, and the thickness ratio is the thickness at 300 hPa at the second compression and the thickness at 300 hPa at the first compression. The value divided by (reference thickness) is applied. The thermal conductivity was measured at an average temperature of 24 ° C. using an auto lambda manufactured by Eihiro Seiki.

Example 1
As the short glass fibers constituting the laminate applied to the core material, soda-lime glass mainly composed of general-purpose glass cullet is applied. However, since the short glass fiber is reinforced by the heating and quenching method, it has high strength and low brittleness.

  At this time, the air temperature during rapid cooling was set to 30 ° C.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.65, and the thickness ratio was 0.905.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0016 W / mK, an improvement of 0.0003 W / mK compared to the conventional product. Similarly, the core density of the vacuum heat insulating material is 245 kg / m ³ , which is 2% lower than the conventional 250 kg / m ³ .

  The reason why such a result was obtained is that the compressive strength ratio when the laminate constituting the core material is repeatedly subjected to the compression test is 0.65, and similarly the thickness ratio is 0.905. Compared to products, even when compressed by atmospheric pressure, the fiber is less likely to be bent or broken, and the void formed by the entanglement of the fiber is retained, enabling the atmospheric pressure to be maintained with fewer fiber contact points. I think because it became.

  As a result, since the amount of heat transfer in the thickness direction of the core material is reduced, the heat insulating performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced.

(Example 2)
As the short glass fibers constituting the laminate applied to the core material, soda-lime glass mainly composed of general-purpose glass cullet is applied. However, since the short glass fiber is reinforced by the heating and quenching method, it has high strength and low brittleness.

  At this time, the air temperature during rapid cooling was set to 30 ° C.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.75, and the thickness ratio was 0.915 as well.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0015 W / mK, an improvement of 0.0004 W / mK compared to the conventional product. Similarly, the core density of the vacuum heat insulating material is 240 kg / m ³ , which is conventionally 4% lower than that of 250 kg / m ³ .

  The reason why such a result was obtained is that the compression strength ratio when the laminate constituting the core material is repeatedly subjected to the compression test is 0.75, and similarly the thickness ratio is 0.915. Compared to products, even when compressed by atmospheric pressure, the fiber is less likely to be bent or broken, and the void formed by the entanglement of the fiber is retained, enabling the atmospheric pressure to be maintained with fewer fiber contact points. I think because it became.

  As a result, since the amount of heat transfer in the thickness direction of the core material is reduced, the heat insulating performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced.

(Example 3)
As the short glass fibers constituting the laminate applied to the core material, soda-lime glass mainly composed of general-purpose glass cullet is applied. However, since the short glass fiber is reinforced by the heating and quenching method, it has high strength and low brittleness.

  At this time, the air temperature during the rapid cooling was reduced from 30 ° C. to 10 ° C.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.84, and the thickness ratio was 0.930. The reason why the compressive strength ratio and the thickness ratio are increased in this way is considered to be that the quenching effect is more prominent by reducing the air temperature during quenching from 30 ° C. to 10 ° C.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0015 W / mK, an improvement of 0.0004 W / mK compared to the conventional product. Similarly, the core density of the vacuum heat insulating material is 240 kg / m ³ , which is conventionally 4% lower than that of 250 kg / m ³ .

  The above results are considered to be improved by the same action as in Example 1.

Example 4
As the short glass fibers constituting the laminate applied to the core material, soda-lime glass mainly composed of general-purpose glass cullet is applied. However, since the short glass fiber is reinforced by hydrofluoric acid treatment, it has high strength and low brittleness.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.85, and the thickness ratio was 0.931 in the same manner. These values were almost the same as those at the time of quenching at an air temperature of 10 ° C. in the heating and quenching method.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0014 W / mK, an improvement of 0.0005 W / mK compared to the conventional product. Similarly, the core density of the vacuum heat insulating material is 240 kg / m ³ , which is conventionally 4% lower than that of 250 kg / m ³ .

  The above results are considered to be improved by the same action as in Example 1.

(Example 5)
As the short glass fibers constituting the laminate applied to the core material, soda-lime glass mainly composed of general-purpose glass cullet is applied. However, since the short glass fiber is reinforced by ion exchange treatment, it has high strength and low brittleness.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.90, and the thickness ratio was 0.942. These values are increased as compared with the heating and quenching method, and the ion exchange treatment is considered to be more effective.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0014 W / mK, an improvement of 0.0005 W / mK compared to the conventional product. Similarly, the core density of the vacuum heat insulating material is 240 kg / m ³ , which is conventionally 4% lower than that of 250 kg / m ³ .

  The above results are considered to be improved by the same action as in Example 1.

(Example 6)
The E glass which is an alkali free glass is applied to the glass short fiber which comprises the laminated body applied to a core material. E glass has a Young's modulus of the glass composition itself about 10% larger than that of soda lime glass. As a result, the tensile strength of the fiber is increasing.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.80, and the thickness ratio was 0.930.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0014 W / mK, an improvement of 0.0005 W / mK compared to the conventional product. Similarly, the core density of the vacuum heat insulating material is 235 kg / m ³ , which is conventionally reduced by 6% compared to 250 kg / m ³ .

  Although the above result is considered to be improved by the same action as in Example 1, it can be seen that the heat insulation performance can be improved by changing the glass composition.

(Comparative Example 1)
A general soda-lime glass is applied as the glass short fiber to the glass composition forming the short glass fiber of the fibrous material applied to the core material. Similarly, since the glass fiber is not specially treated, it is a conventional short glass fiber having general-purpose material properties.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.63, and the thickness ratio was similarly 0.895.

At this time, the heat conductivity of the vacuum heat insulating material was 0.0019 W / mK, and the core material density of the vacuum heat insulating material was 250 kg / m ³ .

(Comparative Example 2)
The glass composition forming the short glass fibers of the fibrous material applied to the core material is a soda-lime glass that doubles the alkali content and is added with 5 mol% of barium oxide. Note that the amount of silicon oxide is reduced by the amount of increase in alkali and barium oxide.

  The glass fiber was fiberized by a general method without any special treatment.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.50, and the thickness ratio was 0.880.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0022 W / mK, which was 0.0003 W / mK worse than the conventional product. Similarly, the density of the core material of the vacuum heat insulating material was 280 kg / m ³ , which was increased as compared with the conventional 250 kg / m ³ .

As mentioned above, since the vacuum heat insulating material manufactured with the manufacturing method of the vacuum heat insulating material concerning this invention has the outstanding heat insulation performance, high heat insulation performance is obtained by thinner thickness. Therefore, in addition to uses such as a refrigerator and a cooler box, the present invention can be applied to uses that require high heat insulation performance in a narrow space such as a liquid crystal projector, a copy machine, and a notebook computer.

Sectional schematic diagram of the vacuum heat insulating material in Embodiment 1 of this invention Sectional schematic diagram of the vacuum heat insulating material in Embodiment 2 of this invention Plane schematic diagram of the vacuum heat insulating material in Embodiment 3 of this invention Cross-sectional schematic diagram of the vacuum heat insulating material along the A-A 'line in FIG. Cross-sectional view of a conventional vacuum insulation core

Explanation of symbols

1,31 Vacuum insulation material 2,32 Core material 3,33 Jacket material

  The present invention relates to a method for manufacturing a vacuum heat insulating material in which a core material is covered with a jacket material and the inside is sealed under reduced pressure, and a vacuum heat insulating material manufactured by the manufacturing method.

  As the core material used for the vacuum heat insulating material, an inorganic compound having a low thermal conductivity and a low gas generation is suitable. In particular, a vacuum heat insulating material using a glass fiber laminate as a core material is known to have excellent heat insulating performance, and is shown in FIG. 5 as an example of a core material constituting the vacuum heat insulating material. There is.

  FIG. 5 shows that the inorganic fine fibers 91a are randomly laminated so that the length direction thereof is perpendicular to the heat transfer direction and the length directions of the inorganic fine fibers 91a intersect each other. It is provided with a penetration fiber 91b that forms a high-density inorganic fine fiber mat 9 by being driven into contact with the laminated thin fiber 91a in parallel with the heat transfer direction. It has been proposed to form a core material by superimposing sheets (N sheets) (see, for example, Patent Document 1).

  In the conventional vacuum heat insulating material configured as described above, since the inorganic small-diameter fibers 91a are arranged randomly and perpendicularly to the heat transfer direction, the fibers 91a are in point contact with each other. The contact heat resistance at the contact point is large, and the heat transfer amount in the core thickness direction is small.

  However, only the fiber 91a arranged perpendicular to the heat transfer direction reduces the compression resistance against atmospheric pressure acting in the heat transfer direction, and the core material is compressed by the atmospheric pressure acting after vacuum packaging, making it difficult to ensure thickness. Become.

Therefore, the penetration fibers 91b are partially arranged in parallel with the heat transfer direction. However, since the heat insulation performance is lowered by the penetration fibers 91b, a core material is formed by superimposing a plurality of (N) inorganic thin fiber mats 9, and the amount of heat transferred by the penetration fibers 91b is reduced.
Japanese Examined Patent Publication No. 7-103955

  However, in the above conventional configuration, even if the core material is formed by superimposing a plurality of (N) inorganic thin fiber mats 9 and the amount of heat transfer by the penetration fibers 91b is reduced, it is arranged in parallel to the heat transfer direction. Since the penetration fibers 91b, that is, the fibers 91b themselves act as heat bridges that directly transfer heat, it is difficult to reduce the amount of heat transfer. Moreover, since the heat | fever conducts with the heat conductivity intrinsic | native to glass material in the fiber 91b arrange | positioned in parallel with the heat transfer direction, the amount of heat transfer increases in proportion to the number of fibers arrange | positioned in parallel with the heat transfer direction.

  Therefore, the subject that the heat insulation performance of the vacuum heat insulating material deteriorated in proportion to the quantity of the glass fiber 91b arrange | positioned in parallel with the heat-transfer direction occurred.

  On the other hand, in the core material comprised only of the glass fiber 91a arrange | positioned substantially perpendicular | vertical with respect to the heat transfer direction, there existed a subject that the heat insulation performance of a vacuum heat insulating material deteriorated for the following reason.

  When the glass fiber constituting the core material does not have sufficient strength, the fiber constituting the core material is bent or broken by atmospheric pressure. When the bending of the fibers proceeds, the void portion of the core material formed by the entanglement between the fibers is crushed, and the number of contact points between the fibers increases. As a result, the number of heat transfer paths increases and, in part, the contact area increases due to contact of the fibers from point contact to line contact, etc., so the contact thermal resistance decreases.

  In addition, when the fiber breaks, as in the case where the bending of the fiber proceeds, the void portion of the core material formed by the entanglement between the fibers is crushed, and the number of contact points between the fibers increases. Specifically, the contact thermal resistance decreases because the contact area increases, for example, where the fiber comes into contact with line contact. Furthermore, the void portion of the core material formed by the entanglement between the fibers is filled with the broken fiber, the void of the core material is further reduced, and the number of contact points of the fiber is also increased.

  For this reason, the amount of heat transfer is increased, the heat insulation performance of the vacuum heat insulating material is reduced, and the thickness of the core material cannot be secured, and the amount of the fibrous substance constituting the core material needs to be increased. There was a problem that the material cost increased.

  The present invention solves the above-described conventional problems, and provides a method for producing a vacuum heat insulating material that can further improve the heat insulating performance, improve the compression resistance of the core material, and reduce the material cost for the core material. For the purpose.

To achieve the above object, the manufacturing method of the vacuum heat insulating material of the present invention is a short glass fibers used an average fiber diameter of 3~5μm glass wool made of soda lime glass, a high temperature immediately after the fiberizing Using the short glass fiber in which the temperature of the cooling air is adjusted by a heating and quenching method in which cooling air is blown against the short glass fiber, and the fiber is reinforced to have a predetermined strength or more , the length direction is the heat transfer direction. configure the core material having the characteristics of (a) by forming a laminate by laminating the thickness direction while randomly arranged so as to intersect and cross so as to be substantially perpendicular to, the core material Is covered with a jacket material, the inside of the jacket material is decompressed, and hermetically sealed by heat welding . However, the property (a) is based on the thickness of the laminate when the compression strength becomes 300 hPa during the first compression in the case where the operation of releasing the compression immediately after the laminate is compressed to 1013 hPa is repeated. and the thickness, the compressive strength ratio obtained by dividing the compressive strength at the reference thickness at the time of the second compressed 300hPa is made 0.65 or more.

The inventor of the present invention adjusts the temperature of the cooling air by a heating and quenching method in which cooling air is blown against high-temperature short glass fibers immediately after fiberization to strengthen the fibers to have a strength of a predetermined level or more. laminate short fibers the longitudinal direction is constructed by laminating in the thickness direction while disposed randomly so as to intersect and cross so as to be substantially perpendicular to the heat transfer direction, a time of repeated compression It has been found that the decrease in compressive strength at the reference thickness is reduced, and that the heat insulating performance of the vacuum heat insulating material is improved by applying this laminate to the core material of the vacuum heat insulating material.

  As a result, the short glass fibers constituting the laminate are low in brittleness and strong in fiber strength. Therefore, even when compressed by atmospheric pressure, the fibers are not easily bent or broken, and voids formed by entanglement of fibers. Is retained. In addition, since the fiber itself is difficult to break, the original fiber length is long since the fiber was manufactured.

As a result, even a laminate structure laminated in the thickness direction while disposed randomly so short glass fiber length thereof intersects the and each other so as to be substantially perpendicular to the heat transfer direction, Since the short glass fibers have the same action as the leaf springs, it is possible to maintain the atmospheric pressure with a smaller number of contact points between the fibers, and the number of heat transfer paths in the thickness direction of the core material is reduced.

Further, the short glass fibers are randomly arranged so that the length direction thereof is substantially perpendicular to the heat transfer direction and cross each other, and are laminated in the thickness direction of the core material. Since the fiber length of the short fiber is longer than that of the conventional product, the lamination state is further improved, and the heat transfer distance in the thickness direction of the core material is increased.

  For the above reason, since the heat transfer amount in the thickness direction of the core material decreases, the heat insulating performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, the core material can be reduced in density, and at the same time, a vacuum heat insulating material that realizes cost reduction of the core material is provided. be able to.

The manufacturing method of vacuum insulation material of another aspect of the present invention, a glass staple fibers using average fiber diameter of 3~5μm glass wool made of soda lime glass, immediately after fiberization hot glass short Using the short glass fiber that has been reinforced so that the fiber has a strength of a predetermined level or more by adjusting the temperature of the cooling air by a heating and quenching method in which cooling air is blown onto the fiber , the length direction of the fiber is in the heat transfer direction. while randomly arranged so as to intersect and cross so as to be substantially perpendicular to constitute the core material having the characteristics of by forming a laminate by laminating the thickness direction (b), the jacket of the core material It is a method for producing a vacuum heat insulating material, characterized in that it is covered with a material, the inside of the jacket material is decompressed, and hermetically sealed by thermal welding . However, the characteristic (b) is based on the thickness of the laminate when the compression strength is 300 hPa during the first compression in the case where the operation of quickly releasing the compression is repeated after compressing the laminate to 1013 hPa. and thickness, in which the second thickness ratio compressive strength at the time of compression by dividing the thickness of the laminate when the 300hPa in the reference thickness is 0.9 or more.

  In this invention as well, the heat insulation performance of the vacuum heat insulating material is improved because the amount of heat transfer in the thickness direction of the core material is reduced by the same action as the previous invention.

  Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced. As a result, it is possible to provide a vacuum heat insulating material that realizes cost reduction of the core material.

  Moreover, like the previous invention, management can be easily performed by substituting the compression characteristics in the laminated body of short glass fibers, and the entire image of the laminated body can be easily grasped more specifically.

  In the vacuum heat insulating material manufactured by the method for manufacturing a vacuum heat insulating material of the present invention, the heat transfer performance in the thickness direction of the core material is reduced, so that the heat insulating performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material is increased, and the density of the core material can be reduced. Therefore, it is possible to provide a vacuum heat insulating material that realizes high performance and cost reduction of the core material.

According to one aspect of the present invention, a short glass fibers using average fiber diameter of 3~5μm glass wool made of soda lime glass, a cooling air to a high temperature of the glass wool immediately after the fiberizing By using the short glass fibers reinforced by adjusting the temperature of the cooling air by a spraying heating and quenching method so that the fibers have a predetermined strength or more , the length direction thereof is substantially perpendicular to the heat transfer direction. In addition , a core material having the characteristics of (a) is formed by laminating in the thickness direction while being randomly arranged so as to cross each other, thereby forming a core material having the characteristics of (a), covering the core material with a jacket material, A method for producing a vacuum heat insulating material, characterized in that the inside of a workpiece is decompressed and hermetically sealed by heat welding . However, the property (a) is based on the thickness of the laminate when the compression strength becomes 300 hPa during the first compression in the case where the operation of releasing the compression immediately after the laminate is compressed to 1013 hPa is repeated. and the thickness, the compressive strength ratio obtained by dividing the compressive strength at the reference thickness at the time of the second compressed 300hPa is made 0.65 or more.

  In general, the destruction of the glass composition is a typical brittle fracture from a low temperature to a normal temperature, and the fracture occurs rapidly under a critical stress. Such fracture of a brittle solid occurs when the bonds between atoms are broken by the tensile stress and the atoms are separated.

  However, since there are actually flaws called large and small Griffith flows on the surface and inside of the glass, these become stress concentration sources, and breakage occurs under load stress much lower than the theoretical value. This is one of the causes of glass brittleness.

Even in the case of short glass fibers, the temperature of the cooling air is adjusted by a heating and quenching method in which cooling air is blown against high-temperature short glass fibers immediately after fiberization, and the fibers are reinforced to have a predetermined strength or more , and By making the glass itself brittle, the fiber is less likely to break against a load stress such as compression. As a result, the laminate is less reduced in compressive strength at the reference thickness during repeated compression.

  Therefore, even in a vacuum heat insulating material in which a core material composed of a laminate of short glass fibers is covered with an outer cover material and the inside is decompressed, the fibers constituting the core material by compressing the core material by atmospheric pressure after vacuum packaging Even when a tensile stress is applied to the fiber, the fiber is not easily broken, and the voids of the core material formed by the entanglement of the fiber are maintained. This means that the core material shape can be maintained against the atmospheric pressure with a smaller number of fiber contact points, and the number of heat transfer paths in the core material thickness direction is reduced. Become.

  Thus, by applying the short glass fiber having low brittleness and high fiber strength to the core material, the heat transfer performance in the thickness direction of the core material is reduced, so that the heat insulation performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and at the same time, the density of the core material can be reduced. As a result, it is possible to provide a vacuum heat insulating material that realizes cost reduction of the core material.

Moreover, when the laminated body of short glass fibers is repeatedly compressed, the laminated body of short glass fibers such that the compression strength ratio obtained by dividing the compressive strength at the reference thickness at the second compression by 300 hPa is 0.65 or more. Since the amount of heat transfer in the thickness direction of the core material is reduced by using as the core material of the vacuum heat insulating material, the heat insulating performance of the vacuum heat insulating material is improved.

  Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced. As a result, it is possible to provide a vacuum heat insulating material that realizes cost reduction of the core material.

  Moreover, it is essential to manage the brittle characteristics of short glass fibers by the tensile strength of the fibers. However, in practice, the short glass fibers constituting the laminate have a wide distribution in the fiber strength, and therefore the measurement required to grasp the overall image of the short glass fibers requires a great deal of labor. Therefore, as shown in the present invention, management can be easily performed by substituting the compression characteristics of the short glass fiber laminate, and the overall image of the laminate can be more easily grasped.

  In short, it has been newly found that the repeated compressive strength ratio obtained by this test method has a good correlation with the thermal conductivity of the vacuum heat insulating material.

On the other hand, the amount of compression at the time of repeated compression is set to 1013 hPa in terms of compressive strength is set because the vacuum heat insulating material in which the laminated body is vacuum-packed is constantly subjected to atmospheric pressure, but it is a problem that it slightly varies Absent. However, since even when a pressurized at an intensity of 2 times the atmospheric pressure of the low brittleness, or high-strength fibers progresses fiber breakage, by dividing the compressive strength at the reference thickness at the time of the second compressed 300hPa Since the compression strength ratio may be less than 0.65, the compression strength during repeated compression is desirably 1013 hPa.

  Moreover, the reference thickness at the time of repeated compression is the thickness of the laminate at 300 hPa. The compression strength ratio at the time of repeated compression varies depending on the compression strength as the reference thickness, but the laminate at 300 hPa This is because the correlation with the heat insulating performance of the vacuum heat insulating material becomes clear when the thickness is used as a reference.

  The compression strength ratio in the repeated compression test is a value obtained by dividing the second compression strength at the reference thickness by 300 hPa that sets the reference thickness.

According to a second aspect of the invention, a glass staple fibers using the average fiber diameter of 3~5μm glass wool made of soda lime glass, a cooling air to a high temperature of the glass wool immediately after the fiberizing By using the short glass fibers reinforced by adjusting the temperature of the cooling air by a spraying heating and quenching method so that the fibers have a predetermined strength or more , the length direction thereof is substantially perpendicular to the heat transfer direction. In addition , a core material having the characteristics of (b) is formed by stacking in the thickness direction while being randomly arranged so as to cross each other , thereby covering the core material with a jacket material, A method for producing a vacuum heat insulating material, characterized in that the inside of a workpiece is decompressed and hermetically sealed by heat welding . However, the characteristic (b) is based on the thickness of the laminate when the compression strength is 300 hPa during the first compression in the case where the operation of quickly releasing the compression is repeated after compressing the laminate to 1013 hPa. and thickness, in which the second thickness ratio compressive strength at the time of compression by dividing the thickness of the laminate when the 300hPa in the reference thickness is 0.9 or more.

When repeatedly compressing the stack of glass wool, glass such as divided by the thickness ratio is 0.9 or more the thickness of the laminate when the compressive strength during the second compression is 300hPa in the reference thickness By using the short fiber laminate as the core material of the vacuum heat insulating material, the heat transfer performance in the thickness direction of the core material is reduced due to the same action as the invention of claim 1, so that the heat insulating performance of the vacuum heat insulating material. Will improve.

  Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced. As a result, it is possible to provide a vacuum heat insulating material that realizes cost reduction of the core material.

  As in the first aspect of the invention, management can be easily performed by substituting the compression characteristics of the short glass fiber laminate, and the overall image of the laminate can be more easily grasped.

  In addition, when the laminated body of short glass fibers is formed into a board shape by binder or thermoforming, the heat transfer amount in the thickness direction of the core material is reduced, so that the heat insulating performance of the vacuum heat insulating material is improved.

  Further, since the compression resistance of the core material is improved, the porosity of the core material can be increased and the density of the core material can be reduced. As a result, it is possible to provide a vacuum heat insulating material that realizes cost reduction of the core material.

  Furthermore, when the short glass fiber laminate is formed into a board by binder or thermoforming, the bulk of the laminate can be reduced and the board is given rigidity, so when the board size is large However, its handling is greatly improved.

  In addition, also when it uses as a core material without shape | molding the laminated body of a glass short fiber in board shape, since the heat transfer amount of the thickness direction of a core material falls, the heat insulation performance of a vacuum heat insulating material improves.

  Further, since the compression resistance of the core material is improved, the porosity of the core material can be increased and the density of the core material can be reduced. As a result, it is possible to provide a vacuum heat insulating material that realizes cost reduction of the core material.

  Moreover, if the laminated body of short glass fibers is applied as a core material without forming into a board shape, the load stress on the short glass fibers constituting the laminated body becomes smaller, and the progress of breakage of the short glass fibers is most suppressed. Therefore, more excellent heat insulation performance can be realized in the vacuum heat insulating material.

  Thus, the glass short fiber applied as a core material of a vacuum heat insulating material can improve the heat insulation performance of a vacuum heat insulating material, so that it is low brittle and the fiber strength is large. Moreover, the density reduction of a vacuum heat insulating material is realizable, so that the fiber strength is large.

  It is essential to control the brittle properties of short glass fibers by the tensile strength of the fibers. However, in practice, the short glass fibers have a wide distribution of fiber strength, and the measurement required to grasp the overall image of the short glass fibers requires a great deal of labor. Therefore, as shown in the present invention, it is desirable to manage by substituting the compression characteristics in the laminated body of short glass fibers.

  Thus, in order to improve the thermal conductivity of the vacuum heat insulating material, it is desirable that the reduction in the compressive strength at the reference thickness during repeated compression is small in the operation of repeatedly compressing and releasing the glass short fiber laminate.

Invention of Claim 3 is the vacuum heat insulating material manufactured by the manufacturing method of the vacuum heat insulating material of Claim 1 or 2 .

  Hereinafter, the test method for obtaining the repeated compressive strength ratio of the present invention will be specifically described.

  (1) As a pretreatment of the test sample, in order to remove the compression history of the sample due to vacuum packaging or packing, the sample is first compressed to 300 hPa.

  (2) As the first compression, the test sample is compressed to 1013 hPa and quickly released to a predetermined thickness. The thickness at which the compression strength becomes 300 hPa in this compression process is taken as the reference thickness.

  (3) The same compression as the first compression is performed again until the second compression to 1013 hPa. In this compression process, the compressive strength at the reference thickness is measured.

  (4) The repeated compression strength ratio is calculated from the following equation.

Repeated compressive strength ratio = compressive strength at the standard thickness during the second compression / 300 hPa
At this time, a general autograph can be used as the repeated compression test apparatus. As an example of the test conditions, the compression speed is 10 mm / min, the compression jig is an iron circular shape having a diameter of 100 mm both in the upper and lower sides, the test sample is 200 mm × 200 mm in size, and the basis weight is 2500 g / m ² ± 15%. The center part of the sample is compressed and the compressive strength test is repeatedly performed.

  As the short glass fiber that can be used in the present invention, a known fiber can be used, but it is desirable that the fiber diameter is small and the thermal conductivity of the material is small, and the tensile strength of the fiber is 0.5 GPa or more. It is more desirable.

  In addition, the laminate is randomly arranged so that the short glass fibers are substantially perpendicular to the heat transfer direction (thickness direction) in the length direction, and the length directions of the short glass fibers intersect each other. In addition, a laminate of webs formed so that the fibers are in point contact with each other is desirable. Further, the laminate formed by laminating the webs is more preferably a laminate in which the webs are joined by minimum entanglement of fibers capable of maintaining the integrity of the laminate, and are uniformly laminated in the thickness direction. is there. By setting it as such a laminated body, the contact heat resistance between fibers becomes more dominant than the heat conductivity intrinsic | native to a glass composition in the heat transfer amount of a core material thickness direction.

  As an example, the thermal conductivity of the general-purpose glass composition at room temperature is around 1 W / mK, and the short glass fibers are arranged so that the length direction thereof is substantially perpendicular to the heat transfer direction, and the short glass fibers are used. In the case of a vacuum heat insulating material having a core of a laminate in which the length directions of the layers are randomly arranged so as to cross each other, that is, a laminate in which webs are laminated, the apparent heat related to the solid component of the laminate The conductivity is 1/100 or less of the glass composition itself.

  The fiber diameter is not particularly specified, but finer fiber diameter can provide better heat insulation performance. However, it is desirable to use one having an average fiber diameter of 3 to 5 μm from the viewpoint of economy.

  On the other hand, an example of a method for making short glass fibers low brittle and high in strength is as follows.

  The short glass fiber applicable to the present invention can make the short glass fiber low brittle and high in strength by optimizing the glass composition and the manufacturing process. Among these, methods for increasing the strength of short glass fibers by optimizing the manufacturing process include a method called a chemical strengthening method or an ion exchange method, and a method called a heating rapid cooling method or an air cooling strengthening method.

  The chemical strengthening method is a method in which the glass surface is eroded with hydrofluoric acid or the like, and thereby the Griffith flow existing on the glass surface can be removed, so that the brittleness and strength of the short glass fiber can be improved.

  In addition, the ion exchange method is a method in which a high compressive stress layer is applied to the glass surface in advance by replacing sodium ions on the glass surface with potassium ions having a large molecular diameter. Similarly, the brittleness and strength of the glass are improved. it can.

  However, the heating and cooling method is most used industrially. This is processed by spraying low-temperature air on heated glass, and by applying a high compressive stress layer to the surface of the glass in advance, durability against tensile stress is improved. This method can be similarly applied to glass fibers, and glass fibers are reinforced by blowing cooling air on high-temperature fibers immediately after fiberization, so that the glass fibers can be efficiently processed.

  As mentioned above, although the glass strengthening method utilized industrially was shown, the method of strengthening the mechanical strength of glass fiber is not limited to what was mentioned above, A well-known method is applicable.

  On the other hand, it is more desirable that the laminate film forming the covering material that can be used in the present invention is composed of a plastic film having at least one of a metal foil layer and a vapor deposition layer in order to impart high gas barrier properties. At this time, a known material can be used for the metal foil layer and the vapor deposition layer, and is not particularly specified.

  In addition, the lamination film is preferably formed by a dry lamination method using an adhesive for dry lamination, but an extrusion lamination method in which a part of the laminate film is melt extruded using an olefin resin is applied. Also good.

  Hereinafter, embodiments 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 schematic cross-sectional view of a vacuum heat insulating material manufactured by the method for manufacturing a vacuum heat insulating material in Embodiment 1 of the present invention.

  In FIG. 1, the vacuum heat insulating material 1 is configured by inserting a core material 2 and an adsorbent 4 into an outer cover material 3 and reducing the pressure inside. At this time, the core material 2 is adjusted so that the vacuum heat insulating material has a thickness of 10 mm.

  The vacuum heat insulating material 1 is prepared by drying the core material 2 in a drying furnace at 140 ° C. for 20 minutes, and then inserting the three sides of the laminate film into the envelope material 3 formed into a bag shape by heat sealing. The pressure inside the jacket 3 is reduced to 10 Pa or less, and the opening is hermetically sealed by heat welding.

  On the other hand, the glass short fiber applied to the core material 2 is glass wool having an average fiber diameter of 3.5 μm. However, the glass wool uses a general-purpose soda-lime glass composition, but immediately after fiberization, the glass wool is rapidly cooled by blowing cooling air to reinforce the fibers.

  The core material 2 is produced by laminating glass wool made of short glass fiber webs to a predetermined thickness, and molding a laminated body in which the webs are joined by entanglement. Then, the board-shaped core material is shape | molded by thermoforming the laminated body of a short glass fiber with a hot press at 450 degreeC lower than the distortion point of glass for 5 minutes.

  In addition to the above method, a board-like core material having higher rigidity can be formed by applying a binder during hot pressing. These can be determined in consideration of the required quality and productivity of the vacuum heat insulating material.

  The jacket material 3 is composed of a plastic laminate film in which a polyethylene terephthalate film (12 μm) is applied to the outermost layer, an aluminum foil (6 μm) is applied to the intermediate layer, and a linear low density polyethylene film (50 μm) is applied to the heat-welded layer. .

  The adsorbent 4 uses calcium oxide as a moisture adsorbent.

  About the vacuum heat insulating material 1 produced in this way, the thermal conductivity was measured with an auto lambda manufactured by Eihiro Seiki. As a result, the heat conductivity of the vacuum heat insulating material 1 has an excellent heat insulating performance of 0.0015 W / mK at an average temperature of 24 ° C., and the compression strength ratio in the repeated compression test of the laminate is 0.8. there were.

  This means that the thermal conductivity is reduced by 0.0004 W / mK compared to a vacuum heat insulating material in which a core material is formed from a laminate of conventional short glass fibers having a compression strength ratio of less than 0.65 in a repeated compression test. I understood.

Similarly, the core material density required to make the vacuum heat insulating material 1 10 mm thick is conventionally 250 kg / m ³ , but in the present embodiment it is 240 kg / m ³ .

  The reason why such a result was obtained is that the compression strength ratio in the repeated compression test of the laminate is 0.8, so even if the core material is compressed by atmospheric pressure compared to the conventional product, the bending of the fiber It is considered that breakage hardly occurs, voids formed by fiber entanglement are maintained, and atmospheric pressure can be maintained with a smaller number of fiber contact points.

  As a result, since the amount of heat transfer in the thickness direction of the core material is reduced, the heat insulating performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced. Therefore, in this Embodiment, since the usage-amount of glass wool can be reduced 4%, reduction of raw material cost is also realizable.

  In this embodiment, as the short glass fibers forming the core material, glass wool, which is a general-purpose industrial material, is applied, and the heating and quenching method is performed so that the compression strength ratio in the repeated compression test of the laminate is 0.65 or more. The fiber is reinforced and applied.

  However, the short glass fiber that can be applied to the core material can be applied without any particular problem as long as the short glass fiber has low brittleness and high strength. However, desirably, a laminate of short glass fibers having a compression strength ratio of 0.65 or more in a repeated compression test of the laminate, more desirably, a laminate of short glass fibers having a compression strength ratio of 0.70 or more, More preferably, it is a laminate of short glass fibers having a compressive strength ratio of 0.75 or more.

  In addition, although the compressive strength ratio greatly reduces the thermal conductivity at the boundary of 0.65, if the compressive strength ratio exceeds 0.75, no further decrease in the thermal conductivity can be confirmed. Therefore, when the compressive strength ratio is in the range of 0.65 or 0.75, the thermal conductivity tends to decrease as the compressive strength ratio increases.

  The repeated compression test was carried out using an iron circular jig having a diameter of 100 mm using an autograph made by Shimadzu Corporation. At this time, the compression speed was 10 mm / min. In addition, in order to unify the compression load history of the test material and suppress the test variation, this test was performed after the compression treatment was once performed as a pretreatment until the compression strength reached 300 hPa. The compressive strength ratio is shown as an average of n = 3.

(Embodiment 2)
FIG. 2 is a schematic cross-sectional view of a vacuum heat insulating material manufactured by the method for manufacturing a vacuum heat insulating material in Embodiment 2 of the present invention.

  In FIG. 2, the vacuum heat insulating material 11 is configured by inserting a core material 12 and an adsorbent 14 into an outer cover material 13 and reducing the pressure inside. At this time, the core material 12 is adjusted so that the vacuum heat insulating material has a thickness of 10 mm.

  The core material 2 was produced by laminating glass wool made of short glass fiber webs to a predetermined thickness, and molding a laminate in which the webs were joined by entanglement. At this time, the core material 12 is used as a core material without forming the laminated body into a board shape by binder or thermoforming.

  In addition, the vacuum heat insulating material 11 in this Embodiment 2 is the same as that of the material structure in 1st Embodiment, and a preparation method except the manufacturing method of the core material 12 differing.

  The short glass fibers applied to the core material 12 were glass wool having an average fiber diameter of 3.5 μm, and the compression strength ratio in the repeated compression test of the laminate was 0.80.

  About the vacuum heat insulating material 11 produced in this way, the thermal conductivity was measured with an auto lambda manufactured by Eihiro Seiki. As a result, the heat conductivity of the vacuum heat insulating material 11 has an excellent heat insulating performance of 0.0014 W / mK at an average temperature of 24 ° C., and the compression strength ratio in the repeated compression test is less than 0.65. It was found that the thermal conductivity was reduced by 0.0005 W / mK as compared with a vacuum heat insulating material in which a core material was formed from a laminate of short glass fibers.

  Further, compared to the case of Embodiment 1 in which a laminated body of short glass fibers is formed into a board shape by thermoforming, vacuum insulation is used although the compression strength ratio in the repeated compression test of the laminated body is equivalent. The insulation performance of the material was further improved.

Similarly, the core material density required to make the vacuum heat insulating material 11 10 mm thick has been 235 kg / m ³ in the present embodiment, which was conventionally 250 kg / m ³ .

  The reason why such a result was obtained is that the compression strength ratio in the repeated compression test of the laminate is 0.80, so that the fiber is bent or broken even when compressed by atmospheric pressure as compared with the conventional product. This is considered to be because the voids formed by the entanglement of the fibers are not easily generated and the atmospheric pressure can be maintained with a smaller number of contact points of the fibers.

  As a result, since the amount of heat transfer in the thickness direction of the core material is reduced, the heat insulating performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced. Therefore, in this Embodiment, since the usage-amount of glass wool can be reduced 6%, reduction of raw material cost is also realizable.

(Embodiment 3)
FIG. 3 is a schematic plan view of a vacuum heat insulating material manufactured by the method for manufacturing a vacuum heat insulating material in Embodiment 3 of the present invention. FIG. 4 is a schematic cross-sectional view of the vacuum heat insulating material taken along line AA ′ of FIG.

  In FIG. 3, a vacuum heat insulating material 31 is formed by sealing a plurality of core materials 32 with a gas barrier outer covering material 33 under reduced pressure, and the core materials 32 are held in independent vacuum spaces by shaded heat welding portions 34. Has been.

  The manufacturing method of the vacuum heat insulating material 31 first installs a pair of upper and lower laminated films facing each other in the vacuum chamber. At this time, a plurality of core materials 32 dried at 140 ° C. for 20 minutes are fixed to the upper side surface of the lower laminate film by a known method such as heat welding in advance. Thereafter, the pressure is reduced so that the periphery of the core material 32 becomes 10 Pa or less, and the upper and lower laminated films that have been heated in advance are heat-welded including the core material 32 part, so that the plurality of core materials 32 are each core material. Laminate films facing to the vicinity of the periphery of 32 are thermally welded to form a thermally welded portion 34, and the core members 32 are held in independent vacuum spaces.

  In addition, the vacuum heat insulating material 31 in this Embodiment 3 is the same as that of the material structure demonstrated in Embodiment 1 except the manufacturing method of the vacuum heat insulating material 31 differing. However, a moisture adsorbent is used for the vacuum heat insulating material 31, and the thickness of the core material 32 part of the vacuum heat insulating material 31 is adjusted to 5 mm.

  The short glass fibers applied to the core material 32 were glass wool having an average fiber diameter of 3.5 μm, and the compression strength ratio in the repeated compression test of the laminate was 0.76.

  About the vacuum heat insulating material 31 produced in this way, the core part part thermal conductivity was measured with the auto-lambda made from Eihiro Seiki. As a result, the core part thermal conductivity of the vacuum heat insulating material 31 has an excellent heat insulating performance of 0.0015 W / mK at an average temperature of 24 ° C., and the compression strength ratio in the repeated compression test is less than 0.65. It was found that the thermal conductivity was reduced by 0.0004 W / mK as compared with a conventional vacuum heat insulating material in which a core material was formed from a laminate of short glass fibers.

Similarly, the core material density required to make the vacuum heat insulating material 31 5 mm thick is conventionally 250 kg / m ³ , but 240 kg / m ³ in the present embodiment.

  The reason why such a result was obtained is that the compression strength ratio in the repeated compression test of the laminate is 0.76, so that the fiber is bent or broken even when compressed by atmospheric pressure as compared with the conventional product. This is considered to be because the voids formed by the entanglement of the fibers are not easily generated and the atmospheric pressure can be maintained with a smaller number of contact points of the fibers.

  As a result, the amount of heat transfer in the thickness direction of the core material 32 is reduced, so that the heat insulating performance of the vacuum heat insulating material 31 is improved. Furthermore, since the compression resistance of the core material 32 is improved, the porosity of the core material 32 can be increased and the density of the core material 32 can be reduced. Therefore, in this Embodiment, since the usage-amount of glass wool can be reduced 4%, reduction of raw material cost is also realizable.

  Hereinafter, the characteristics in the repeated compression test of the short glass fibers constituting the core material of the vacuum heat insulating material of the present invention will be described in detail using examples and comparative examples, but the present invention is limited only to the examples. Is not to be done.

  (Table 1) When the glass reinforcing method of the short glass fiber used for the core material and the glass composition are variously changed, the compression strength ratio and the thickness ratio in the repeated compression test, and the thermal conductivity of the vacuum heat insulating material The relationship with the density is shown in Examples 1 to 6 and Comparative Example 1 or 2.

真空断熱材は、基本的に、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１の芯材２を構成するガラス短繊維のガラス強化方法を種々変化させて作製している。

The vacuum heat insulating material is basically manufactured by the same method as in the first embodiment, but is manufactured by changing the glass reinforcing method of the short glass fiber constituting the core material 2 of the vacuum heat insulating material 1 in various ways. Yes.

  Moreover, the glass composition is evaluated with three compositions of A to C. A is soda lime glass (C glass), B is alkali-free glass (E glass), and C is twice the alkali content in soda lime glass. In addition, 5 mol% of barium oxide was added. Note that C reduces the amount of silicon oxide by the increased amount of alkali and barium oxide.

  Furthermore, about soda-lime glass, the glass is tempered by the heating rapid cooling method, hydrofluoric acid treatment, and the ion exchange method.

  On the other hand, the compression strength ratio and the thickness ratio in the repeated compression test are shown as average values of n = 3, respectively, using an autograph manufactured by Shimadzu Corporation. At this time, the compression strength ratio is a value obtained by dividing the second compression strength at the reference thickness by the compression strength of 300 hPa, and the thickness ratio is the thickness at 300 hPa at the second compression and the thickness at 300 hPa at the first compression. The value divided by (reference thickness) is applied. The thermal conductivity was measured at an average temperature of 24 ° C. using an auto lambda manufactured by Eihiro Seiki.

Example 1
As the short glass fibers constituting the laminate applied to the core material, soda-lime glass mainly composed of general-purpose glass cullet is applied. However, since the short glass fiber is reinforced by the heating and quenching method, it has high strength and low brittleness.

  At this time, the air temperature during rapid cooling was set to 30 ° C.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.65, and the thickness ratio was 0.905.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0016 W / mK, an improvement of 0.0003 W / mK compared to the conventional product. Similarly, the core density of the vacuum heat insulating material is 245 kg / m ³ , which is 2% lower than the conventional 250 kg / m ³ .

  The reason why such a result was obtained is that the compressive strength ratio when the laminate constituting the core material is repeatedly subjected to the compression test is 0.65, and similarly the thickness ratio is 0.905. Compared to products, even when compressed by atmospheric pressure, the fiber is less likely to be bent or broken, and the void formed by the entanglement of the fiber is retained, enabling the atmospheric pressure to be maintained with fewer fiber contact points. I think because it became.

  As a result, since the amount of heat transfer in the thickness direction of the core material is reduced, the heat insulating performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced.

(Example 2)
As the short glass fibers constituting the laminate applied to the core material, soda-lime glass mainly composed of general-purpose glass cullet is applied. However, since the short glass fiber is reinforced by the heating and quenching method, it has high strength and low brittleness.

  At this time, the air temperature during rapid cooling was set to 30 ° C.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.75, and the thickness ratio was 0.915 as well.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0015 W / mK, an improvement of 0.0004 W / mK compared to the conventional product. Similarly, the core density of the vacuum heat insulating material is 240 kg / m ³ , which is conventionally 4% lower than that of 250 kg / m ³ .

  The reason why such a result was obtained is that the compression strength ratio when the laminate constituting the core material is repeatedly subjected to the compression test is 0.75, and similarly the thickness ratio is 0.915. Compared to products, even when compressed by atmospheric pressure, the fiber is less likely to be bent or broken, and the void formed by the entanglement of the fiber is retained, enabling the atmospheric pressure to be maintained with fewer fiber contact points. I think because it became.

  As a result, since the amount of heat transfer in the thickness direction of the core material is reduced, the heat insulating performance of the vacuum heat insulating material is improved. Furthermore, since the compression resistance of the core material is improved, the porosity of the core material can be increased, and the density of the core material can be reduced.

(Example 3)
As the short glass fibers constituting the laminate applied to the core material, soda-lime glass mainly composed of general-purpose glass cullet is applied. However, since the short glass fiber is reinforced by the heating and quenching method, it has high strength and low brittleness.

  At this time, the air temperature during the rapid cooling was reduced from 30 ° C. to 10 ° C.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.84, and the thickness ratio was 0.930. The reason why the compressive strength ratio and the thickness ratio are increased in this way is considered to be that the quenching effect is more prominent by reducing the air temperature during quenching from 30 ° C. to 10 ° C.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0015 W / mK, an improvement of 0.0004 W / mK compared to the conventional product. Similarly, the core density of the vacuum heat insulating material is 240 kg / m ³ , which is conventionally 4% lower than that of 250 kg / m ³ .

  The above results are considered to be improved by the same action as in Example 1.

Example 4
As the short glass fibers constituting the laminate applied to the core material, soda-lime glass mainly composed of general-purpose glass cullet is applied. However, since the short glass fiber is reinforced by hydrofluoric acid treatment, it has high strength and low brittleness.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.85, and the thickness ratio was 0.931 in the same manner. These values were almost the same as those at the time of quenching at an air temperature of 10 ° C. in the heating and quenching method.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0014 W / mK, an improvement of 0.0005 W / mK compared to the conventional product. Similarly, the core density of the vacuum heat insulating material is 240 kg / m ³ , which is conventionally 4% lower than that of 250 kg / m ³ .

  The above results are considered to be improved by the same action as in Example 1.

(Example 5)
As the short glass fibers constituting the laminate applied to the core material, soda-lime glass mainly composed of general-purpose glass cullet is applied. However, since the short glass fiber is reinforced by ion exchange treatment, it has high strength and low brittleness.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.90, and the thickness ratio was 0.942. These values are increased as compared with the heating and quenching method, and the ion exchange treatment is considered to be more effective.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0014 W / mK, an improvement of 0.0005 W / mK compared to the conventional product. Similarly, the core density of the vacuum heat insulating material is 240 kg / m ³ , which is conventionally 4% lower than that of 250 kg / m ³ .

  The above results are considered to be improved by the same action as in Example 1.

(Example 6)
The E glass which is an alkali free glass is applied to the glass short fiber which comprises the laminated body applied to a core material. E glass has a Young's modulus of the glass composition itself about 10% larger than that of soda lime glass. As a result, the tensile strength of the fiber is increasing.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.80, and the thickness ratio was 0.930.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0014 W / mK, an improvement of 0.0005 W / mK compared to the conventional product. Similarly, the core density of the vacuum heat insulating material is 235 kg / m ³ , which is conventionally reduced by 6% compared to 250 kg / m ³ .

  Although the above result is considered to be improved by the same action as in Example 1, it can be seen that the heat insulation performance can be improved by changing the glass composition.

(Comparative Example 1)
A general soda-lime glass is applied as the glass short fiber to the glass composition forming the short glass fiber of the fibrous material applied to the core material. Similarly, since the glass fiber is not specially treated, it is a conventional short glass fiber having general-purpose material properties.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.63, and the thickness ratio was similarly 0.895.

At this time, the heat conductivity of the vacuum heat insulating material was 0.0019 W / mK, and the core material density of the vacuum heat insulating material was 250 kg / m ³ .

(Comparative Example 2)
The glass composition forming the short glass fibers of the fibrous material applied to the core material is a soda-lime glass that doubles the alkali content and is added with 5 mol% of barium oxide. Note that the amount of silicon oxide is reduced by the amount of increase in alkali and barium oxide.

  The glass fiber was fiberized by a general method without any special treatment.

  In the laminate of short glass fibers, the compression strength ratio when the repeated compression test was performed was 0.50, and the thickness ratio was 0.880.

At this time, the thermal conductivity of the vacuum heat insulating material was 0.0022 W / mK, which was 0.0003 W / mK worse than the conventional product. Similarly, the density of the core material of the vacuum heat insulating material was 280 kg / m ³ , which was increased as compared with the conventional 250 kg / m ³ .

  As mentioned above, since the vacuum heat insulating material manufactured with the manufacturing method of the vacuum heat insulating material concerning this invention has the outstanding heat insulation performance, high heat insulation performance is obtained by thinner thickness. Therefore, in addition to uses such as a refrigerator and a cooler box, the present invention can be applied to uses that require high heat insulation performance in a narrow space such as a liquid crystal projector, a copy machine, and a notebook computer.

Sectional schematic diagram of the vacuum heat insulating material manufactured by the manufacturing method of the vacuum heat insulating material in Embodiment 1 of this invention Sectional schematic diagram of the vacuum heat insulating material manufactured by the manufacturing method of the vacuum heat insulating material in Embodiment 2 of this invention Plane schematic diagram of the vacuum heat insulating material manufactured by the manufacturing method of the vacuum heat insulating material in Embodiment 3 of this invention Cross-sectional schematic diagram of the vacuum heat insulating material along the A-A 'line in FIG. Cross-sectional view of a conventional vacuum insulation core

Explanation of symbols

1,31 Vacuum insulation material 2,32 Core material 3,33 Jacket material

Claims (2)

  A vacuum heat insulating material formed by covering a core material composed of a laminated body of short glass fibers with an outer covering material and reducing the pressure inside the outer covering material, and the short glass fibers constituting the laminated body are in a heat transfer direction. In the case of repeating the operation of releasing the compression promptly after the laminate is compressed to 1013 hPa after being arranged substantially vertically and randomly and laminated in the thickness direction of the core material. A vacuum heat insulating material in which the thickness of the laminate when the compressive strength is 300 hPa is a reference thickness, and the ratio of the compressive strength at the reference thickness at the second compression to 300 hPa and 300 hPa is 0.65 or more.   A vacuum heat insulating material formed by covering a core material composed of a laminate of short glass fibers with an outer covering material and reducing the pressure inside the outer covering material, wherein the short glass fibers constituting the laminated body are in a heat transfer direction. In the case of repeating the operation of releasing the compression promptly after the laminate is compressed to 1013 hPa after being arranged substantially vertically and randomly and laminated in the thickness direction of the core material. A vacuum in which the thickness of the laminate when the compressive strength is 300 hPa is a reference thickness, and the ratio of the thickness of the laminate when the compressive strength is 300 hPa during the second compression to the reference thickness is 0.9 or more. Insulation.

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