JP2012217942A - Gas adsorbing material and vacuum insulation material obtained by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas adsorbing material in which deterioration in the nitrogen adsorptivity of copper ion-exchanged ZSM-5 zeolite due to adsorbing steam (moisture) is suppressed.SOLUTION: The gas adsorbing material 1 is obtained by covering the periphery of the copper ion-exchanged ZSM-5 zeolite 2, which has 8-25 silica/alumina ratio in a zeolite skeleton, with a moisture chemically-adsorbing material 3 which has the water adsorptivity higher than that of the copper ion-exchanged ZSM-5 zeolite 2. A gas adsorbing material pack 4 is obtained by packing the gas adsorbing material 1 in a three-side sealed bag of a low-density polyethylene film 5, which has moderate gas permeability and 15 μm thickness, and heat-sealing an opening of the gas adsorbing material-packed bag.

Description

  The present invention relates to a gas adsorbent and a vacuum heat insulating material using the same.

  In recent years, there has been an active movement to promote energy conservation as a countermeasure against global warming, which is a global environmental problem, and with regard to equipment that uses heat and cold heat, a vacuum heat insulating material with excellent heat insulation performance from the viewpoint of effective use of heat. Is spreading.

  A vacuum heat insulating material is a gas-barrier laminated film processed into a bag-like shape, and a core material having a high gas phase volume ratio and a fine gap is inserted like glass wool, and the core material is sealed under reduced pressure. is there.

  By making the gap diameter of the core material smaller than the mean free path of gas molecules under reduced pressure, the gas heat conduction component becomes small, and the influence of the convective heat transfer component can be ignored in a fine gap of about 1 mm. become.

  Furthermore, since the influence of the radiation component is slight near room temperature, the heat conduction in the vacuum heat insulating material is dominated by the solid heat conduction component of the core material and the slightly remaining gas heat conduction component. The thermal conductivity is said to be very small compared to other heat insulating materials.

  However, when air gradually enters the vacuum heat insulating material through the laminate film, the gas heat conduction component increases, so that the heat conductivity of the vacuum heat insulating material gradually increases.

  As means for solving such a problem, a nitrogen adsorbent using a Ba-Li alloy which is a non-evaporable barium getter has been proposed (see Patent Document 1).

  Furthermore, a vacuum getter has been proposed in which a getter material containing a Ba-Li alloy and a desiccant that can simultaneously adsorb moisture is enclosed in an aluminum container (see Patent Document 2).

  Further, as a method for removing impurity gases such as nitrogen from the gas to be purified, an adsorbent made of ZSM-5 type zeolite subjected to copper ion exchange has been proposed (see Patent Document 3).

  In the configurations disclosed in Patent Document 1 and Patent Document 2, it is possible to chemically adsorb nitrogen, but since it is an alloy material, the getter itself has high thermal conductivity, and the constituent material Ba is PRTR. It is a designated substance and has restrictions on the work environment.

  Further, in the configuration disclosed in Patent Document 3, nitrogen can be adsorbed in a dry state, but since it has a higher reactivity with moisture than nitrogen, water vapor (moisture) always present in the heat insulating material and elapsed time are present. At the same time, it is oxidized by water vapor (water) that gradually enters and becomes inactive to nitrogen.

  As a means for solving these problems, a gas adsorbent in which the periphery of a ZSM-5 type zeolite subjected to copper ion exchange having a silica to alumina ratio in the zeolite framework of 8 to 25 is covered with a chemical moisture adsorbent has been proposed. (See Patent Document 4).

JP-A-5-131134 Japanese National Patent Publication No. 9-512088 JP 2003-31148 A JP 2006-043604 A

  However, even with the configuration disclosed in Patent Document 4, the ZSM-5 type zeolite in which the adsorption activity (adsorption energy on the surface) with respect to water vapor (moisture) is exchanged with copper ions is larger than the chemical moisture adsorbent. In some cases, the ZSM-5 type zeolite exchanged with copper ions selectively adsorbs water vapor (moisture), which may cause a problem of reducing nitrogen adsorption activity.

  Therefore, the present invention provides a gas adsorbent capable of suppressing the reduction of nitrogen adsorption activity of ZSM-5 type zeolite subjected to copper ion exchange due to adsorption of water vapor (water), and a vacuum heat insulating material using the same. It is aimed.

  In order to achieve the above object, the gas adsorbent according to the present invention is a gas adsorbent used for adsorbing air in a closed space and maintaining a reduced pressure state of the closed space, wherein silica vs. alumina in a zeolite skeleton is used. The periphery of the ZSM-5 type zeolite subjected to the copper ion exchange having a ratio of 8 or more and 25 or less was covered with a chemical moisture adsorbent having a higher adsorption activity for water than the ZSM-5 type zeolite subjected to the copper ion exchange.

  With the above configuration, the chemical moisture adsorbent comes into contact with water vapor (moisture) first and adsorbs and immobilizes the water vapor (moisture). However, the chemical moisture adsorbent is more resistant to water than ZSM-5 type zeolite exchanged with copper ions. Because the adsorption activity is high, the ZSM-5 type zeolite exchanged with copper ions through the gap of the chemical moisture adsorbent that covers the periphery of the ZSM-5 type zeolite that is not adsorbed by the chemical moisture adsorbent and that is exchanged with copper ions. The amount of water vapor (moisture) that reaches is reduced, and the activity of the ZSM-5 type zeolite that has undergone copper ion exchange is not lost due to water vapor (water). Suppress. Therefore, a gas adsorbent having a large capacity of nitrogen adsorption can be obtained.

  Further, the vacuum heat insulating material of the present invention comprises at least a core material and a gas adsorbent pack in which the gas adsorbing material of the present invention is filled in a bag having an appropriate gas permeability with an outer covering material having a gas barrier property. Covering and depressurizing the inside of the jacket material.

  In the above configuration, since the gas adsorbent is filled in a bag having appropriate gas permeability, the concentration of water vapor entering with the passage of time is thin, most of which is selectively used as a chemical moisture adsorbent. ZSM-5 type zeolite that has been adsorbed and immobilized and subjected to copper ion exchange can maintain high nitrogen adsorption activity over a long period of time. Therefore, the vacuum heat insulating material provided with the gas adsorbent does not deteriorate for a long time.

  Since the gas adsorbent of the present invention adsorbs and immobilizes moisture prior to the ZSM-5 type zeolite in which the chemical water adsorbent has exchanged copper ions, the decrease in nitrogen adsorption activity of the ZSM-5 type zeolite in which copper ions have been exchanged. Suppress. Therefore, a gas adsorbent having a large capacity of nitrogen adsorption can be obtained. Moreover, the vacuum heat insulating material using it does not deteriorate for a long time.

The schematic diagram of the gas adsorbent in Embodiment 1 of this invention Schematic diagram of the gas adsorbent pack in Embodiment 2 of the present invention Model sectional drawing showing the vacuum heat insulating material in Embodiment 2 of this invention

  1st invention is the gas adsorption material used in order to adsorb | suck the air of closed space, and to maintain the pressure reduction state of the said closed space, Comprising: The copper ion whose silica-to-alumina ratio in a zeolite frame is 8-25 The periphery of the exchanged ZSM-5 type zeolite is covered with a chemical moisture adsorbent having a higher adsorption activity for water than that of the ZSM-5 type zeolite exchanged with copper ions.

  With the above configuration, the chemical moisture adsorbent comes into contact with water vapor (moisture) first and adsorbs and immobilizes the water vapor (moisture). However, the chemical moisture adsorbent is more resistant to water than ZSM-5 type zeolite exchanged with copper ions. Because the adsorption activity is high, the ZSM-5 type zeolite exchanged with copper ions through the gap of the chemical moisture adsorbent that covers the periphery of the ZSM-5 type zeolite that is not adsorbed by the chemical moisture adsorbent and that is exchanged with copper ions. The amount of water vapor (moisture) that reaches is reduced, and the activity of the ZSM-5 type zeolite that has undergone copper ion exchange is not lost due to water vapor (water). Suppress. Therefore, a gas adsorbent having a large capacity of nitrogen adsorption can be obtained.

  First, a method for preparing a copper ion exchanged ZSM-5 type zeolite having a silica to alumina ratio in the zeolite skeleton of 8 to 25 will be described.

First, copper ion exchange is performed on sodium-type zeolite having a silica to alumina ratio of 8 to 25 in the ZSM-5 type zeolite framework. Ion exchange can be performed by a known method that has been performed conventionally, but is generally a method of immersing in an aqueous solution of a soluble salt of copper such as an aqueous solution of copper chloride or an aqueous solution of copper ammine, and in particular, copper propionate. A method using a Cu ²⁺ solution containing carboxylate such as (II) or copper (II) acetate or a method using a copper nitrate (II) solution has high nitrogen adsorption activity.

  The copper ion exchange rate is preferably at least 50% of the ion exchangeable amount.

After ion exchange, it is fully recommended, dried, and then subjected to appropriate heat treatment under low pressure, so that Cu ²⁺ introduced by ion exchange is reduced to Cu ⁴⁺ and speaks nitrogen adsorption ability. is there.

  The pressure during the heat treatment is 10 mPa or less, preferably 1 mPa or less, and the temperature is 350 ° C. or higher, preferably 500 ° C. or higher.

  Next, a method for producing the gas adsorbent of the present invention will be described. ZSM-5 type zeolite exchanged with copper ions with a silica-to-alumina ratio of 8 to 25 in the zeolite skeleton that has been subjected to heat treatment and nitrogen adsorption activity is an inert gas such as Ar without contact with nitrogen, water, or oxygen. Mix so that the surroundings are covered with a chemical moisture adsorbent under an atmosphere.

  At this time, the chemical water adsorbent having a relation larger than the activity of water of the chemical water adsorbent mixed in the surrounding is selected than the activity of the ZSM-5 type zeolite substituted with the obtained copper ion with respect to water. To do.

  The larger the difference in the activity, the better. However, practically, the difference in activity is preferably twice or more.

  In addition, the thing which carry | supported the copper monovalent ion to ZSM-5 type zeolite has no harmful information, and it is thought that an environmental load is also low.

  In the second invention, at least the core material and the gas adsorbent pack filled with the gas adsorbent of the first invention in a bag having appropriate gas permeability are covered with a jacket material having gas barrier properties. The inside of the jacket material is decompressed.

  In the above configuration, the ZSM-5 type zeolite exchanged with copper ions having a silica-to-alumina ratio of 8 to 25 in the zeolite skeleton in the gas adsorbent of the first invention cannot be removed by an industrial vacuum exhaust process. As a result, it is possible to improve the heat insulation performance of the vacuum heat insulating material, while the gas adsorbing material is filled in a bag having an appropriate gas permeability, so that the remaining water can be absorbed at once. It does not flow into the gas adsorbent, and the activity of the chemical moisture adsorbent constituting the gas adsorbent with respect to water is greater than the activity of copper ion-exchanged ZSM-5 type zeolite with respect to water. The moisture that has passed through the chemical moisture adsorbent reaches the ZSM-5 type zeolite that has undergone copper ion exchange, and the amount of water that reaches the ZSM-5 type zeolite has undergone copper ion exchange. It is not reduced nitrogen adsorption capacity of the yarn.

  As the core material used in the present invention, open cell bodies such as polyurethane and polystyrene, inorganic fibers such as glass fibers and ceramic fibers, organic fibers such as polyester fibers, and inorganic powders such as silica and pearlite can be used. . Moreover, those composites may be sufficient.

  Moreover, a low density polyethylene film, a polypropylene film, etc. can be used for the bag which has moderate gas permeability. Alternatively, the gas barrier property may be adjusted so that a minute gas enters from the hole by drilling those films. Alternatively, as the nonwoven fabric, a polyester fiber and a polypropylene fiber that are heated and stretched, or a nonwoven fabric that is made by a spunbond method can be used.

  At this time, “moderate” means that the film can be selected depending on the amount of water remaining. When the amount of remaining water is large, the material has a low water vapor transmission rate. When the amount of water remaining is small, the film has a high water vapor transmission rate. It is preferable to select a material and select a gas permeability that is as large as possible.

  The gas gas barrier properties of these films are determined by the water vapor permeability and nitrogen permeability of the films, but the thickness can be determined according to the gas barrier properties.

  Further, the jacket material plays a role of maintaining the vacuum degree of the vacuum heat insulating material, and is a heat-welded film as the innermost layer, and a resin film on which metal foil or metal atoms are vapor-deposited as a gas barrier film as an intermediate layer A laminate film in which a surface protective film is laminated as the outermost layer can be used.

  The heat welding film is not particularly specified, but is a thermoplastic resin such as a low density polyethylene film, a linear low density polyethylene film, a high density polyethylene film, a polypropylene film, a polyacrylonitrile film, or a mixture thereof. Can be used.

  Moreover, as a gas barrier film, metal foils, such as aluminum foil and copper foil, the film which vapor-deposited metals and metal oxides, such as aluminum and copper, to a polyethylene terephthalate film or an ethylene-vinyl alcohol copolymer etc. can be used.

In addition, the chemical moisture adsorbing material can be placed in the middle of the core material by placing the chemical water adsorbing material in contact with the outer shell or in the middle of the core material. preferable.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the same components as those of the above-described embodiments will be denoted by the same reference numerals, and detailed description thereof will be omitted. The present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a schematic diagram of a gas adsorbent according to Embodiment 1 of the present invention.

  A gas adsorbent 1 according to the present embodiment is a gas adsorbent 1 used for adsorbing air in a closed space and maintaining a reduced pressure state in the closed space, and is silica-alumina in a zeolite skeleton having nitrogen adsorption activity. A copper ion exchanged ZSM-5 type zeolite 2 having a ratio of 8 or more and 25 or less and a chemical water adsorbent 3, and around the ZSM-5 type zeolite 2 subjected to copper ion exchange, the chemical water adsorbent 3 The chemical water adsorbing material 3 has a higher adsorption activity for water than the ZSM-5 type zeolite subjected to the copper ion exchange.

  With the above configuration, the chemical moisture adsorbing material 3 comes into contact with water vapor (moisture) first and adsorbs and immobilizes the water vapor (moisture). The chemical moisture adsorbing material 3 is obtained from the ZSM-5 type zeolite 2 exchanged with copper ions. Since the adsorption activity to water is also high, the copper ions are exchanged through the gap of the chemical moisture adsorbing material 3 that covers the periphery of the ZSM-5 type zeolite 2 that is not adsorbed by the chemical moisture adsorbing material 3 and is subjected to the copper ion exchange. Since the amount of water vapor (moisture) reaching the ZSM-5 type zeolite 2 decreases and the activity of the ZSM-5 type zeolite 2 subjected to copper ion exchange is not lost by the water vapor (water content), the ZSM-5 subjected to copper ion exchange Suppression of nitrogen adsorption activity of type 2 zeolite 2 is suppressed. For this reason, the gas adsorbent 1 of the present embodiment has a large capacity of nitrogen adsorption.

(Embodiment 2)
FIG. 2 is a schematic diagram of a gas adsorbent according to Embodiment 2 of the present invention. FIG. 3 is a schematic cross-sectional view showing a vacuum heat insulating material in Embodiment 2 of the present invention.

  As shown in FIGS. 2 and 3, the vacuum heat insulating material 6 of the present embodiment includes a core material 7 made of glass fiber and the gas adsorbing material 1 of the first embodiment having a thickness of 15 μm and appropriate gas permeability. A gas adsorbent pack 4 filled in a three-side sealed bag of low-density polyethylene film 5 and packed in an opening of the bag by heat sealing is covered with a jacket material 8 made of a laminate film having a gas barrier property. The pressure inside is reduced.

  In the present embodiment, the gas adsorbent 1 is filled in a bag made of a low-density polyethylene film 5 having a suitable gas permeability and having a thickness of 15 μm. Most of them are selectively adsorbed and immobilized on the chemical moisture adsorbent 3, and the ZSM-5 type zeolite 2 exchanged with copper ions can maintain a high nitrogen adsorption activity over a long period of time. Therefore, the vacuum heat insulating material 6 provided with the gas adsorbent 1 does not deteriorate for a long time.

Further, the ZSM-5 type zeolite 2 which is exchanged with copper ions having a silica-to-alumina ratio of 8 to 25 in the zeolite skeleton in the gas adsorbent 1 adsorbs nitrogen that cannot be removed by an industrial vacuum exhaust process. As a result, while the heat insulation performance of the vacuum heat insulating material 6 can be improved, the gas adsorbent 1 is filled in a bag of a low density polyethylene film 5 having a thickness of 15 μm and having an appropriate gas permeability. The remaining moisture does not flow into the gas adsorbent 1 at once, and the activity of the chemical moisture adsorbent 3 constituting the gas adsorbent 1 with respect to water is exchanged with copper ions of the ZSM-5 type zeolite 2 Since the activity with respect to water is larger, the remaining water passes through the chemical water adsorbent 3 and reaches the ZSM-5 type zeolite 2 subjected to the copper ion exchange. It does not decrease the nitrogen adsorption capacity of the ZSM-5 type zeolite 2 was copper ion exchange.

Example 1
A copper ion-exchanged ZSM-5 type zeolite 2 having a silica-to-alumina ratio of 8 to 25 with nitrogen adsorption ability and calcium oxide as a chemical water adsorbent 3 were prepared, and the activity with respect to water was measured.

  As a method for measuring the activity of calcium oxide, 25 g of a sample is placed in 1 L of warm water (containing a BTB indicator), and neutralization titration is performed with a 4N hydrochloric acid aqueous solution while stirring. Thereafter, the amount of 4N hydrochloric acid aqueous solution consumed for 10 minutes was defined as the activity.

  As a result, the activity of calcium oxide was 223 ml.

  Since the activity of the ZSM-5 type zeolite 2 exchanged with copper ions cannot be measured by the same measurement, a change in humidity was measured in a desiccator and compared with the activity of calcium oxide with respect to water.

  The calcium oxide was placed in a desiccator adjusted to 95% RH, and after standing for 10 minutes, the humidity was 4% RH.

  On the other hand, the ZSM-5 type zeolite 2 subjected to the copper ion exchange was put in a desiccator similarly adjusted to 95% RH, and the humidity after 10 minutes became 12%.

  The gas adsorbent 1 in which 90% of the calcium oxide and 10% of ZSM-5 type zeolite exchanged with copper ion are mixed is inserted into the core material 7 made of glass fiber and the jacket material 8 made of a laminate film, and the chamber pressure is increased. The vacuum heat insulating material 6 was produced by evacuating to 1 Pa.

  The heat conductivity of the vacuum heat insulating material 6 was 0.0017 W / mK. In this state, it was left in an atmosphere of 100 ° C., and the thermal conductivity after 200 days was measured to be 0.0019 W / mK.

(Comparative Example 1)
Similarly to Example 1, calcium oxide having a different activity of 125 ml was prepared. Similarly, when the humidity after 10 minutes was measured in a desiccator, the humidity was 27% RH.

  A gas adsorbing material in which 90% of calcium oxide and 10% of ZSM-5 type zeolite exchanged with copper ion are mixed is inserted into a core material 7 made of glass fiber and an outer covering material 8 made of a laminate film, and the chamber pressure is 1 Pa. The vacuum heat insulating material was produced by evacuating until it became.

  The heat conductivity of this vacuum heat insulating material was 0.0017 W / mK. In this state, it was left in an atmosphere of 100 ° C., and the thermal conductivity after 200 days was measured to be 0.0027 W / mK.

  From the comparison between Example 1 and Comparative Example 1, in Example 1, where the activity with respect to water is higher than that of ZSM-5 type zeolite 2 in which calcium oxide is exchanged with copper ions, the thermal conductivity after 200 days is the initial heat. In Comparative Example 1, in which the activity to water is smaller than that of ZSM-5 type zeolite 2 subjected to copper ion exchange, the thermal conductivity after 200 days is 0, while the conductivity is hardly deteriorated. .001 W / mK deteriorated.

  This is within the range of 200 days. In Example 1, air components entering from the outside continue to be adsorbed, whereas in Comparative Example 1, it is considered that they are no longer adsorbed.

(Example 2)
The moisture permeability of the low density polyethylene film at 40 ° C. and 90% RH is 32 g / m ² , and the nitrogen permeability is 4700 cc / m ² · 24H.

  A vacuum heat insulating material was prepared in the same procedure as in Example 1, and the initial thermal conductivity was measured to be 0.0017 W / mK. The thermal conductivity after 200 days at 100 ° C. was also 0.0017 W / mK. It was. This is because the ZSM-5 type zeolite exchanged with copper ions does not deteriorate and maintains a stable adsorption capacity.

  Since the gas adsorbent of the present invention adsorbs and immobilizes moisture prior to the ZSM-5 type zeolite in which the chemical water adsorbent has exchanged copper ions, the decrease in nitrogen adsorption activity of the ZSM-5 type zeolite in which copper ions have been exchanged. Therefore, it has a large capacity of nitrogen adsorption and is suitable for a vacuum heat insulating material. Moreover, the vacuum heat insulating material of this invention can be utilized for all the uses which can apply vacuum heat insulating materials, such as a refrigerator, a jar pot, a rice cooker, a vending machine, and a house.

DESCRIPTION OF SYMBOLS 1 Gas adsorption material 2 Copper ion exchanged ZSM-5 type zeolite 3 Chemical moisture adsorption material 4 Gas adsorption material pack 6 Vacuum heat insulating material 7 Core material 8 Cover material

Claims (2)

A gas adsorbent used for adsorbing air in a closed space and maintaining a reduced pressure state in the closed space, wherein the ratio of silica to alumina in the zeolite framework is from 8 to 25 and is exchanged with copper ions ZSM-5 type A gas adsorbent characterized in that the periphery of zeolite is covered with a chemical moisture adsorbent having a higher adsorption activity for water than the ZSM-5 type zeolite subjected to the copper ion exchange. At least a core material and a gas adsorbent pack filled with the gas adsorbent according to claim 1 in a bag having appropriate gas permeability are covered with a jacket material having a gas barrier property, and the inside of the jacket material is covered. A vacuum heat insulating material characterized by being decompressed.