Partition member for total heat exchange element, total heat exchange element, method for producing partition member for total heat exchange element, and coating fluid

Abstract

The present invention addresses the problem of providing a partition member for a total heat exchange element, the partition member having both excellent gas-barrier properties and moisture permeability even when having a reduced thickness. This partition member for a total heat exchange element comprises a sheet-shaped substrate and, formed on at least one surface thereof, a coating layer containing a binder or microfine fibers of a high-molecular-weight polysaccharide that have a fiber width of 1-1,000 nm, wherein the binder is at least one polymer selected from among water-soluble polymers and water-dispersible polymers. The present invention further relates to: a method for producing the partition member for a total heat exchange element; the total heat exchange element; and a coating fluid for producing the partition member for a total heat exchange element.

Description

Partition member for total heat exchange element, total heat exchange element, manufacturing method of partition member for total heat exchange element, and coating liquid

[0001] The present invention relates to a partition member for a total heat exchange element, a total heat exchange element, a method for manufacturing a partition member for a total heat exchange element, and a coating liquid.

[0002] Conventionally, heat exchange ventilation devices (total heat exchangers) that exchange heat between intake air and exhaust air during ventilation have been proposed as devices that can ventilate without impairing the cooling or heating effects. These total heat exchangers are widely used, and are constructed by stacking multiple partition members (liners) via spacing members to separate an intake air path that introduces outdoor air into the room and an exhaust air path that exhausts indoor air to the outside, and incorporating a total heat exchange element that exchanges sensible heat (temperature) and latent heat (humidity) simultaneously.

[0003] For example, in winter, outdoor air as supply air and indoor air as exhaust air are guided into each flow path separated by a spacing member. In this case, the supply air and the exhaust air exchange temperature and humidity through a partition member. The partition member through which heat exchange occurs has moisture permeability, allowing water vapor to pass through but not air. The partition member also has gas barrier properties by isolating the supply air and the exhaust air. As a result, the supply air is heated and humidified before being supplied to the room, while the exhaust air is cooled and dehumidified before being discharged to the outside. The partition member's moisture permeability and gas barrier properties enable ventilation through total heat exchange. Because such partition members must have both heat conductivity and moisture permeability, paper primarily composed of natural pulp, such as glassine paper, is often used (Patent Document 1).

[0004] In recent years, attempts have also been made to apply cellulose nanofibers, which have gas barrier properties, to partition members (Patent Document 2).

[0005] Japanese Patent No. 4252892 Japanese Patent Application Laid-Open No. 2021-155865

[0006] In the face of growing demands for measures to combat global warming and save energy, total heat exchange elements are attracting attention. In order to further improve the heat exchange efficiency of total heat exchange elements, it is believed that it would be effective to make the partition members thinner than ever before and to increase the number of stacked layers of the total heat exchange element. However, this has been difficult to achieve with the partition members described in Patent Documents 1 and 2.

[0007] Furthermore, if the thickness of the partition member is reduced, it becomes difficult to achieve both gas barrier properties and moisture permeability. Therefore, an object of the present invention is to provide a partition member for a total heat exchange element that achieves both excellent gas barrier properties and moisture permeability even when the thickness of the partition member is reduced.

[0008] Specific embodiments of the present invention are described below. <1> A partition member for a total heat exchange element, comprising a sheet-like substrate and a coating layer on at least one surface thereof, the coating layer containing a binder or fine fibers of a polymeric polysaccharide having a fiber width of 1 to 1,000 nm, the binder being at least one polymer selected from a water-soluble polymer and a water-dispersible polymer. <2> The partition member for a total heat exchange element according to <1>, the coating layer containing fine fibers of a polymeric polysaccharide having a fiber width of 1 to 1,000 nm and a binder. <3> The partition member for a total heat exchange element according to <2>, the binder being a cellulose derivative. <4> The partition member for a total heat exchange element according to <2> or <3>, the binder being at least one selected from carboxymethylcellulose and a salt thereof. <5> The partition member for a total heat exchange element according to any one of <2> to <4>, the binder being an ammonium salt of carboxymethylcellulose. <6> The partition member for a total heat exchange element according to any one of <2> to <5>, wherein the fine fibers are chemically modified fine cellulose fibers. <7> The partition member for a total heat exchange element according to any one of <1> to <6>, wherein the sheet-like substrate is a hydrophobic porous substrate. <8> The partition member for a total heat exchange element according to any one of <1> to <7>, wherein the sheet-like substrate has an Oken air permeability of 1000 seconds or less. <9> The partition member for a total heat exchange element according to any one of <1> to <8>, wherein the sheet-like substrate has a thickness of 5 μm or more and 30 μm or less. <10> The coating amount of the coating layer is 0.03 g / m ２ 3g / m or more ２<11> The partition member for a total heat exchange element according to any one of <1> to <9>, having an Oken air permeability of 10,000 seconds or more. <12> The partition member for a total heat exchange element according to any one of <1> to <10>, having an Oken air permeability of 2,500 g / m or more at a temperature of 20°C and a relative humidity of 65%. ２ The partition member for a total heat exchange element according to any one of <1> to <11>, which has a grammage of 5 to 30 g / m2 and a durability of 24 hours or more. ２<14> The partition member for a total heat exchange element according to any one of <1> to <13>, having an Oken air permeability of 10,000 seconds or more under conditions of 20°C and a relative humidity of 65% after the following water immersion test. "Water immersion test": A sample prepared by cutting the partition member for a total heat exchange element into an A4 size is immersed in 30 liters of tap water. After 10 minutes, the sample is removed and air-dried at room temperature until no water droplets remain on the film surface. <15> A total heat exchange element comprising a plurality of partition members for a total heat exchange element according to any one of <1> to <14>, and spacing members arranged between the partition members for the total heat exchange element to maintain a spacing between adjacent partition members for the total heat exchange element, wherein first air flow paths and second air flow paths are alternately formed with the partition members for the total heat exchange element sandwiched therebetween. <16> A method for producing a partition member for a total heat exchange element, comprising the steps of applying a coating liquid containing a binder or fine fibers of a polymeric polysaccharide having a fiber width of 1 to 1000 nm, and water to at least one surface of a sheet-like substrate, and drying the coating liquid, wherein the binder is at least one polymer selected from water-soluble polymers and water-dispersible polymers. <17> A method for producing a partition member for a total heat exchange element according to <16>, wherein the coating liquid contains fine fibers of a polymeric polysaccharide having a fiber width of 1 to 1000 nm, a binder, and water. <18> A method for producing a partition member for a total heat exchange element according to <17>, wherein the binder is a cellulose derivative. <19> A method for producing a partition member for a total heat exchange element according to <17> or <18>, wherein the binder is at least one selected from carboxymethylcellulose and a salt thereof. <20> A method for producing a partition member for a total heat exchange element according to any one of <17> to <19>, wherein the binder is an ammonium salt of carboxymethylcellulose. <21> The method for producing a partition member for a total heat exchange element according to any one of <17> to <20>, wherein the fine fibers are chemically modified fine cellulose fibers. <22> The method for producing a partition member for a total heat exchange element according to any one of <16> to <21>, wherein the sheet-like substrate is a hydrophobic porous substrate. <23> The method for producing a partition member for a total heat exchange element according to any one of <16> to <22>, wherein the drying temperature in the drying step is 70°C or higher and 130°C or lower.<24> A coating solution for producing a partition member for a total heat exchange element, comprising fine fibers of a polymeric polysaccharide having a fiber width of 1 to 1,000 nm, a binder, and water, wherein the binder is at least one polymer selected from a water-soluble polymer and a water-dispersible polymer. <25> The coating solution for producing a partition member for a total heat exchange element according to <24>, wherein the binder is a cellulose derivative. <26> The coating solution for producing a partition member for a total heat exchange element according to <24> or <25>, wherein the binder is at least one selected from carboxymethyl cellulose and salts thereof. <27> The coating solution for producing a partition member for a total heat exchange element according to any one of <24> to <26>, wherein the binder is an ammonium salt of carboxymethyl cellulose. <28> The coating solution for producing a partition member for a total heat exchange element according to any one of <24> to <27>, wherein the fine fibers are chemically modified fine cellulose fibers.

[0009] According to the present invention, a partition member for a total heat exchange element is provided that has both excellent gas barrier properties and moisture permeability.

[0010] FIG. 1 is a schematic diagram illustrating the structure of a total heat exchange element.

[0011] [Partition member for total heat exchange element] The partition member for a total heat exchange element of the present invention is a gas barrier sheet having a coating layer provided on at least one surface of a sheet-like substrate. The coating layer contains a binder or fine fibers of a polymeric polysaccharide having a fiber width of 1 to 1000 nm, and the binder is at least one polymer selected from water-soluble polymers and water-dispersible polymers. The partition member for a total heat exchange element of the present invention has excellent gas barrier properties. In addition, the partition member for a total heat exchange element of the present invention also has excellent moisture permeability.

[0012] The Oken air permeability of the partition member for a total heat exchange element is preferably 10,000 seconds or more, more preferably 50,000 seconds or more, even more preferably 80,000 seconds or more, and particularly preferably 99,999 seconds or more. The Oken air permeability of the partition member for a total heat exchange element is preferably 150,000 seconds or less. The Oken air permeability of the partition member for a total heat exchange element can be controlled, for example, by appropriately adjusting the composition and physical properties of the coating layer.

[0013] The Oken air permeability of a partition member for a total heat exchange element is a value measured under conditions of 20°C and a relative humidity of 65% in accordance with the Oken air permeability method of JAPAN TAPPI Paper and Pulp Testing Method No. 5-2: 2000. The larger the Oken air permeability value of a partition member for a total heat exchange element, the more excellent the gas barrier property of the partition member for a total heat exchange element can be determined to be.

[0014] In the partition member for a total heat exchange element of the present invention, the Oken air permeability under conditions of 20 ° C. and 65% relative humidity after the water immersion test described below is preferably 10,000 seconds or more, more preferably 20,000 seconds or more, even more preferably 30,000 seconds or more, even more preferably 50,000 seconds or more, and particularly preferably 80,000 seconds or more. Furthermore, the Oken air permeability under conditions of 20 ° C. and 65% relative humidity after the water immersion test described below is preferably 150,000 seconds or less. The Oken air permeability after the water immersion test is a value measured under conditions of 20 ° C. and 65% relative humidity in accordance with the Oken air permeability method of JAPAN TAPPI Paper and Pulp Test Method No. 5-2:2000. The Oken air permeability of the partition member for a total heat exchange element after the water immersion test can be controlled, for example, by appropriately adjusting the composition and physical properties of the coating layer.

[0015] "Water Immersion Test" A sample prepared by cutting a partition member for a total heat exchange element into A4 size was immersed in 30 liters of tap water, and after 10 minutes, the sample was taken out and air-dried at room temperature until no water droplets remained on the film surface.

[0016] A partition member for a total heat exchange element may be exposed to water due to condensation or the like. If the above physical properties are satisfied, the partition member can maintain its function as a partition member for a total heat exchange element even when exposed to water. In this way, the present invention can provide a partition member for a total heat exchange element that has excellent water resistance. A partition member for a total heat exchange element that has excellent water resistance can be obtained, for example, by providing a coating layer as described below.

[0017] The moisture permeability of the partition member for the total heat exchange element at a temperature of 20°C and a relative humidity of 65% is 2500 g / m ２ ・24 hours or more is preferable, 2800 g / m ２More preferably, 24 hours or more, 3000 g / m ２ The moisture permeability of the partition member for a total heat exchange element at a temperature of 20°C and a relative humidity of 65% is 3800 g / m ２ Preferably, it is 24 hours or less. The moisture permeability of the partition member for a total heat exchange element can be controlled, for example, by appropriately adjusting the composition and physical properties of the coating layer. The moisture permeability of the partition member for a total heat exchange element is measured in accordance with JIS Z 0208:1976. A larger moisture permeability value indicates better heat exchange efficiency.

[0018] The basis weight of the partition member for the total heat exchange element is 5 g / m ２ It is preferable that the content is 6 g / m or more. ２ More preferably, it is 7 g / m or more. ２ The basis weight of the partition member for a total heat exchange element is more preferably 30 g / m or more. ２ Preferably, the weight is 25 g / m or less. ２ The basis weight of the partition member for the total heat exchange element is preferably 1 / 2 m or less. ２ The basis weight is the mass per unit area, and is measured in accordance with JIS P 8124: 2011. The basis weight of the partition member for a total heat exchange element can be controlled, for example, by using a sheet-like substrate with a low basis weight and a coating layer with a low coating weight.

[0019] The partition member for a total heat exchange element of the present invention has excellent gas barrier properties and moisture permeability despite being lightweight and having a thin basis weight, and can be used as a partition member with excellent heat exchange efficiency.

[0020] "Sheet-like substrate" The sheet-like substrate is not particularly limited as long as it satisfies the above physical property conditions by forming a coating layer, but it must have a low basis weight and sufficient strength for use as a total heat exchange element. In particular, there is a concern that the strength may be reduced due to moisture in the coating liquid when forming the coating layer or condensation water when exposed to during use, and this must be prevented. If a hydrophobic plastic film is used, strength can be achieved, but moisture permeability cannot be obtained. In the present invention, it is preferable to use a hydrophobic porous substrate.

[0021] The thickness of the sheet-like substrate is not particularly limited, but the thickness of the sheet-like substrate is preferably 5 μm or more, more preferably 10 μm or more. The thickness of the sheet-like substrate is preferably 30 μm or less, more preferably 25 μm or less. By setting the thickness to the lower limit or more, the strength as a partition member is maintained, and by setting it to the upper limit or less, the heat exchange efficiency of sensible heat (temperature) is improved and weight reduction is possible. The thickness of the sheet-like substrate is a value measured in accordance with JIS P 8118:2014.

[0022] The surface density of the sheet substrate is 29 g / m ２ It is preferable that the content is 25 g / m or less, and more preferably 25 g / m ２ More preferably, it is 20 g / m or less. ２ The lower limit is not particularly limited, and the surface density of the sheet-like substrate is 2 g / m or less. ２ It is preferable that the amount is equal to or more than 5 g / m ２ The areal density of the sheet-like substrate can be calculated by dividing the weight of a film cut to a predetermined area by that area.

[0023] The sheet-like substrate is preferably hydrophobic, which can reduce its weight. For example, by making the substrate hydrophobic, it becomes unnecessary to apply a large amount of fine fibers of polymeric polysaccharides to improve gas barrier properties, which makes it easier to reduce its weight.

[0024] The Oken air permeability of the sheet-like substrate is preferably 1000 seconds or less, more preferably 500 seconds or less. The lower limit of the Oken air permeability is not particularly limited, but is preferably 10 seconds or more, more preferably 30 seconds or more, and even more preferably 50 seconds or more. If the Oken air permeability of the sheet-like substrate is within the above range and the sheet-like substrate is porous, heat exchange of latent heat (humidity) is facilitated. Note that even if the Oken air permeability of the sheet-like substrate exceeds 1000 seconds, it is also possible to use a sheet-like substrate in which micropores are formed by corona treatment, laser treatment, etc., and the Oken air permeability is 1000 seconds or less. The Oken air permeability of the sheet-like substrate is a value measured in accordance with the Oken air permeability method of JAPAN TAPPI Paper and Pulp Test Method No. 5-2:2000.

[0025] The sheet-like substrate is preferably a hydrophobic porous substrate, and examples of the hydrophobic porous substrate that can be used include films and nonwoven fabrics made of thermoplastic resins such as polyolefins and polyesters.

[0026] "Coating Layer" In order to enhance the gas barrier properties of the partition member for a total heat exchange element of the present invention, it is preferable to provide a coating layer containing a binder or fine fibers of polymeric polysaccharides having a fiber width of 1 to 1,000 nm on at least one side of the sheet-like substrate (hydrophobic porous substrate), and more preferably to provide a coating layer containing at least fine fibers of polymeric polysaccharides having a fiber width of 1 to 1,000 nm and a cellulose derivative as a binder. As a result, it is easy to achieve an Oken air permeability of 10,000 seconds or more for the partition member for a total heat exchange element. The Oken air permeability of the partition member for a total heat exchange element is more preferably 50,000 seconds or more, even more preferably 80,000 seconds or more, and particularly preferably 99,999 seconds or more.

[0027] In addition, by providing a coating layer on the sheet-like substrate (hydrophobic porous substrate), the Oken air permeability of the partition member for the total heat exchange element is set to 10,000 seconds or more, and the moisture permeability under conditions of 20°C and a relative humidity of 65% is set to 2,500 g / m ２ The partition member for a total heat exchange element of the present invention has a moisture permeability of 2500 g / m at a temperature of 20°C and a relative humidity of 65%. ２・24 hours or more is preferable, 2800 g / m ２ More preferably, 24 hours or more, 3000 g / m ２ ・24 hours or more is more preferable.

[0028] The coating layer preferably contains at least one polymer selected from a water-soluble polymer and a water-dispersible polymer as a binder. The binder enhances the adhesion of the fine fibers of the polymer polysaccharide to the hydrophobic porous substrate, thereby achieving high air permeability. The amount of the coating layer applied to the sheet-like substrate (hydrophobic porous substrate) is not particularly limited, but is preferably 0.03 g / m. ２ 3g / m or more ２ It is preferable that the content is 0.03 g / m or less, and more preferably 0.03 g / m ２ 2g / m or more ２ By coating, the pores of the sheet-like substrate can be blocked with a hydrophilic material, and as a result, the decrease in moisture permeability can be suppressed. Note that, if the coating amount is increased, the gas barrier property improves, but the moisture permeability tends to be impaired. ２ On the other hand, if the coating amount is small, the hole portions are not sufficiently covered and sufficient gas barrier properties tend not to be obtained. ２ It is preferable that this is equal to or greater than this.

[0029] "Water-soluble polymer or water-dispersible polymer (binder)" The coating layer preferably contains at least one polymer (binder) selected from water-soluble polymers and water-dispersible polymers. Water-soluble polymers or water-dispersible polymers can be prepared into aqueous coating solutions, and coating layers formed from such coating solutions have excellent film-forming properties, thereby improving the gas barrier properties of the coating layer. Examples of water-soluble polymers include cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxymethyl cellulose (excluding fine cellulose fibers, as described below), etherified starches such as oxidized starch, cationic starch, urea phosphate esterified starch, and hydroxyethyl etherified starch, starches such as dextrin, proteins such as casein, soy protein, and synthetic protein, polyvinyl alcohols, and polyacrylamides. Examples of water-dispersible polymers include various copolymers such as styrene-butadiene copolymers, styrene-acrylic copolymers, ethylene-vinyl acetate copolymers, butadiene-methyl methacrylate copolymers, vinyl acetate-butyl acrylate copolymers, maleic anhydride copolymers, and acrylic acid-methyl methacrylate copolymers. These can be used alone or in combination as needed. Among them, water-soluble polymers are preferred due to their excellent film-forming properties. That is, the coating layer preferably contains a water-soluble polymer as a binder, more preferably a cellulose derivative, even more preferably at least one selected from the group consisting of carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxymethyl cellulose, or at least one selected from salts thereof, even more preferably at least one selected from carboxymethyl cellulose and its salts, and particularly preferably an ammonium salt of carboxymethyl cellulose. Cellulose derivatives have a structure similar to the fine fibers of polymeric polysaccharides, and after film formation, the coating layer has excellent moisture permeability. Furthermore, a coating layer using at least one selected from carboxymethyl cellulose and its salts is preferred because it can achieve excellent gas barrier properties and high moisture permeability. Note that binders other than cellulose derivatives may be used in combination as long as the effects of the present invention are not impaired.

[0030] "Polymer polysaccharide fine fibers" The coating layer preferably contains polymer polysaccharide fine fibers having a fiber width of 1 to 1000 nm. The coating layer also preferably contains polymer polysaccharide fine fibers and a binder. A coating liquid containing polymer polysaccharide fine fibers is applied so that the polymer polysaccharide fine fibers cover at least the pores of the sheet-like substrate (hydrophobic porous substrate). By applying a coating liquid further containing polymer polysaccharide fine fibers to the sheet-like substrate (hydrophobic porous substrate), it is possible to achieve both higher gas barrier properties and higher moisture permeability.

[0031] The fine fibers of polymeric polysaccharides are not particularly limited as long as they are water-insoluble and exhibit gas barrier properties when coated onto a sheet-like substrate (hydrophobic porous substrate). Examples include polymeric polysaccharides such as cellulose, chitin, and chitosan. Polymeric polysaccharides have a molecular structure with many hydroxyl groups (-OH), which allows them to absorb moisture, and the film they form has gas barrier properties.

[0032] The polymer polysaccharide fine fibers have a fiber width of 1 to 1,000 nm, and the use of such fine fibers can further improve gas barrier properties and moisture permeability. In particular, from the viewpoint of gas barrier properties, the fiber width of the polymer polysaccharide fine fibers is preferably 1 to 500 nm, more preferably 1 to 100 nm, and particularly preferably 1 to 30 nm.

[0033] The fine fibers of the polymer polysaccharide are preferably fine cellulose fibers. Fine cellulose fibers are particularly preferred because they form a dense structure when coated and dried, thereby improving gas barrier properties. As the fine cellulose fibers, it is preferable to use fine cellulose fibers having a fiber width of 1 to 1,000 nm. In particular, from the viewpoint of gas barrier properties, the fiber width of the fine cellulose fibers is preferably 1 to 500 nm, more preferably 1 to 100 nm, even more preferably 1 to 30 nm, and particularly preferably 1 to 10 nm. By making the fiber width of the fine cellulose fibers 1 nm or more, dissolution of the cellulose molecules in water is suppressed, and the effect of improving the air permeability and moisture permeability of the fine cellulose fibers is easily achieved. Furthermore, by making the fiber width of the fine cellulose fibers equal to or less than the above upper limit, the gas barrier properties and moisture permeability can be further improved.

[0034] The fiber width of fine cellulose fibers is measured using an electron microscope as follows. First, an aqueous suspension of fine cellulose fibers with a concentration of 0.05% by mass or more and 0.1% by mass or less is prepared, and this suspension is cast on a hydrophilically treated carbon film-coated grid to prepare a sample for TEM observation. When wide fibers are included, an SEM image of the surface cast on glass may be observed. Next, electron microscope images are observed at magnifications of 1,000x, 5,000x, 10,000x, or 50,000x depending on the width of the fibers to be observed. However, the sample, observation conditions, and magnification are adjusted to satisfy the following conditions: (1) A line X is drawn at any location within the observed image, and 20 or more fibers intersect with the line X. (2) A line Y is drawn within the same image, intersecting the line X perpendicularly, and 20 or more fibers intersect with the line Y. For observed images that satisfy the above conditions, the widths of the fibers intersecting with the line X and the line Y are visually read. In this way, three or more sets of observation images of at least the non-overlapping surface portions are obtained. Next, for each image, the widths of the fibers intersecting with line X and line Y are read. This results in reading the widths of at least 20 fibers x 2 x 3 = 120 fibers. The average fiber width is the average value of the fiber widths of the read fine cellulose fibers.

[0035] The fiber length of the microfibrillated cellulose fibers is not particularly limited, but is preferably 0.1 μm or more, and preferably 1,000 μm or less, more preferably 800 μm or less, and even more preferably 600 μm or less. By setting the fiber length of the microfibrillated cellulose fibers within the above range, destruction of the crystalline regions of the microfibrillated cellulose fibers can be suppressed. In addition, it is possible to set the slurry viscosity of the microfibrillated cellulose fibers within an appropriate range, making it easier to form a fiber layer. The fiber length of the microfibrillated cellulose fibers can be determined by image analysis using, for example, TEM, SEM, or AFM.

[0036] The axial ratio (fiber length / fiber width) of the fine cellulose fibers is not particularly limited, but is preferably at least 20, more preferably at least 50, and is preferably at most 10,000, more preferably at most 1,000. By setting the axial ratio within the above range, a slurry viscosity suitable for forming a fiber layer can be obtained.

[0037] In the present invention, the fine cellulose fibers are preferably chemically modified fine cellulose fibers. Specifically, it is preferable that at least one type of group selected from ionic groups and nonionic groups be introduced into the fine cellulose fibers. Furthermore, it is preferable that the ionic groups and nonionic groups be hydrophilic groups. From the viewpoint of improving the dispersibility of the fibers in a dispersion medium and increasing the defibration efficiency in the defibration treatment, it is more preferable that the fine cellulose fibers have ionic groups. The ionic groups may include either or both of anionic groups and cationic groups. In the present invention, it is particularly preferable that the ionic groups have anionic groups. The anionic groups are preferably at least one type selected from a phosphate group, a group derived from a phosphate group, a phosphite group, a group derived from a phosphite group, a carboxy group, a group derived from a carboxy group, a sulfonic acid group, and a group derived from a sulfonic acid group.

[0038] The coating layer of the partition member for a total heat exchange element of the present invention preferably contains a water-soluble or water-dispersible polymer and fine fibers of a polymeric polysaccharide having a fiber width of 1 to 1,000 nm. In the coating layer, the water-soluble or water-dispersible polymer acts as a binder, resulting in improved adhesion to the sheet-like substrate compared to a coating layer formed using fine fibers of a polymeric polysaccharide alone. Furthermore, when a cellulose derivative is used as the water-soluble or water-dispersible polymer, the cellulose derivative has a structure similar to that of fine fibers of a polymeric polysaccharide, resulting in a coating layer with excellent moisture permeability after film formation. Furthermore, a coating layer using at least one selected from carboxymethyl cellulose and its salts can achieve both excellent gas barrier properties and high moisture permeability.

[0039] When polymeric polysaccharide fine fibers having a fiber width of 1 to 1000 nm are used in combination with a binder, the blending ratio of the two is not particularly limited, but the solid content of the binder is preferably 50 to 200 parts by mass, more preferably 60 to 180 parts by mass, and even more preferably 70 to 160 parts by mass per 100 parts by mass of the solid content of the polymeric polysaccharide fine fibers having a fiber width of 1 to 1000 nm. More preferably, the solid content of the cellulose derivative is 50 to 200 parts by mass, more preferably 60 to 180 parts by mass, and even more preferably 70 to 160 parts by mass per 100 parts by mass of the solid content of the polymeric polysaccharide fine fibers having a fiber width of 1 to 1000 nm.

[0040] The partition member for a total heat exchange element of the present invention may be a gas barrier sheet, which has high air permeability and is therefore useful as a variety of gas barrier sheets. In particular, the gas barrier sheet of the present invention has high not only air permeability but also moisture permeability, making it suitable for use as a partition member for a total heat exchange element. Furthermore, when a hydrophobic porous substrate is used as the sheet-like substrate, even if condensation occurs, the mechanical strength is less likely to decrease. Furthermore, because it is lightweight, it is possible to increase the number of stacked layers in a total heat exchange element.

[0041] [Method for manufacturing a partition member for a total heat exchange element] The present invention is a method for manufacturing a partition member for a total heat exchange element, comprising the steps of applying a coating liquid containing a binder or fine fibers of polymeric polysaccharides having a fiber width of 1 to 1000 nm, and water to at least one surface of a sheet-like substrate, and drying the coating liquid. The binder is at least one polymer selected from water-soluble polymers and water-dispersible polymers. The coating liquid preferably contains fine fibers of polymeric polysaccharides having a fiber width of 1 to 1000 nm, a binder, and water. Details of the sheet-like substrate, the fine fibers of polymeric polysaccharides, and the binder are as described above.

[0042] Details of the sheet-like substrate, water-soluble or water-dispersible polymer, and polymeric polysaccharide fine fibers are as described above. The polymeric polysaccharide fine fibers and binder are preferably prepared in the form of an aqueous dispersion and an aqueous solution, respectively, and then mixed to form a coating solution. Depending on the environment in which the total heat exchange element is used, condensation or the like may occur, and the coating layer formed may require water resistance. A water-resistant agent may be added to impart water resistance, but water resistance can be more effectively improved by using, for example, a cellulose derivative, more preferably an ammonium salt of carboxymethylcellulose, as the binder. This is thought to be because the ammonium salt of carboxymethylcellulose evaporates as ammonium upon drying, thereby improving the water resistance of the coating layer itself.

[0043] The coating layer can be formed, for example, by applying a coating liquid containing the above components to a sheet-like substrate and drying it. Known coating machines can be used for the coating method, and are not particularly limited. Blade coaters, bar coaters, curtain coaters, die coaters, air knife coaters, roll coaters, etc. can be used. Blade coaters and bar coaters are particularly preferred because the pressing force of the blade or bar during coating causes the coating liquid to penetrate into the pores of the porous substrate. For drying, a dryer attached to the coating machine can be used. The drying temperature is preferably 65°C or higher, more preferably 70°C or higher, even more preferably 75°C or higher, even more preferably 80°C or higher, even more preferably 85°C or higher, and particularly preferably 90°C or higher. The drying temperature is preferably 130°C or lower, more preferably 120°C or lower, and even more preferably 110°C or lower. By setting the drying temperature to the above lower limit or higher, the water resistance of the coating layer can be more effectively improved. Furthermore, by setting the drying temperature to the above upper limit or less, it is possible to suppress a decrease in strength of the sheet-like substrate due to drying.

[0044] When applying a coating liquid to a sheet-like substrate, if the substrate repels the coating liquid, it is advisable to subject the substrate to a surface hydrophilization treatment such as corona discharge treatment in advance. Furthermore, adding a surfactant (e.g., a wetting agent or a leveling agent) to the coating liquid improves film-forming properties, and a partition member for a total heat exchange element having high air permeability is obtained, which is preferable. It is preferable to use a surfactant with reduced foaming properties.

[0045] The amount of the coating liquid applied to the sheet-like substrate (hydrophobic porous substrate) is not particularly limited, but is preferably 0.03 g / m ２ 3g / m or more ２ It is preferable that the content is 0.03 g / m or less, and more preferably 0.03 g / m ２ 2g / m or more ２ As the coating weight increases, the gas barrier property improves, but the moisture permeability tends to decrease. ２ On the other hand, if the coating amount is small, the hole portions are not sufficiently covered and sufficient gas barrier properties tend not to be obtained. ２The coating amount of the coating liquid is preferably 0.03 g / m or more. ２ 3g / m or more ２ When the thickness is less than 100 μm, a uniform coating film can be formed, and the pores of the substrate can be blocked with the hydrophilic material, thereby suppressing a decrease in moisture permeability. In the present invention, it is preferable to incorporate fine fibers of polymeric polysaccharides into the coating layer, since the fine fibers of polymeric polysaccharides penetrate not only the surface of the hydrophobic porous substrate but also into the interior of the pores, thereby more effectively increasing the moisture permeability.

[0046] Since the partition member of the present invention has a small coating amount of coating liquid, heat exchange of latent heat (humidity) occurs even without the application of a moisture absorbent. However, a moisture absorbent may be blended to further increase moisture permeability. Examples of moisture absorbents include inorganic acid salts, organic acid salts, polyhydric alcohols, and ureas. Examples of inorganic acid salts include lithium chloride, calcium chloride, and magnesium chloride. Examples of organic acid salts include sodium lactate, calcium lactate, and sodium pyrrolidone carboxylate. Examples of polyhydric alcohols include glycerin, ethylene glycol, triethylene glycol, and polyglycerin. Examples of ureas include urea and hydroxyethyl urea.

[0047] Furthermore, the coating liquid may contain auxiliary agents such as water-resistant agents, preservatives, mildew-proofing agents, flame retardants, viscosity adjusters, pH adjusters, colorants, storage stability improvers, polymer resins, and antiblocking agents, as long as the effects of the present invention are not impaired.

[0048] When applying the coating liquid, the amount of coating is adjusted so that the resulting partition member for a total heat exchange element has an Oken air permeability of 10,000 seconds or more. ２ It is preferable to adjust the coating amount so that the coating time is 24 hours or more.

[0049] [Total Heat Exchange Element] The total heat exchange element of the present invention is a total heat exchange element using the above-mentioned partition member for a total heat exchange element. The total heat exchange element of the present invention includes a plurality of the above-mentioned partition members for a total heat exchange element and spacing members arranged between the partition members for a total heat exchange element to maintain a spacing between adjacent partition members for a total heat exchange element, and is a total heat exchange element in which first air flow paths and second air flow paths are formed alternately with the partition members for a total heat exchange element sandwiched therebetween.

[0050] The total heat exchange element will be described below using Fig. 1, but the present invention is not limited to the total heat exchange element with the structure shown in Fig. 1. Fig. 1 is a schematic diagram illustrating the structure of a total heat exchange element 10. As shown in Fig. 1, the total heat exchange element 10 is composed of a plurality of partition members 1 and a plurality of spacing members 2 that form air flow paths between the plurality of partition members 1 and maintain the spacing between the partition members 1. The partition members 1 are flat plates with a square, diamond, or other shape, and the spacing members 2 maintain the spacing between the partition members 1 and are, for example, corrugated plates with a sawtooth or sinusoidal waveform whose projected planar shape matches the shape of the partition members 1.

[0051] The spacing member 2 is not particularly limited as long as it maintains the spacing between the partition members. The spacing member maintains the spacing between the partition members, thereby forming air flow paths between the multiple partition members. The spacing member is not limited to a corrugated material such as a paper substrate, film, or nonwoven fabric, but may also be a resin rib. Among these, a paper substrate is preferred, as the paper substrate has the function of regulating moisture and can compensate for the reduced humidity-regulating function of a partition member using a sheet-like substrate.

[0052] The spacing member 2 has a shape similar to the core of cardboard, for example, and is formed by corrugating. The ridges and valleys of the waveforms of the spacing member 2 are joined to the partition member 1 with an adhesive or the like. The spacing member 2 is joined to the partition member 1 on one side with the partition member 1 in between, with the ridges of the waveforms extending in a first direction (e.g., the vertical direction), and on the other side with the ridges of the waveforms extending in a second direction (e.g., the horizontal direction). In other words, two adjacent spacing members 2 sandwiching the partition member 1 are stacked alternately so that the direction of the ridges of the waveforms on one side and the direction of the ridges of the waveforms on the other side are perpendicular to each other.

[0053] Between the spacing member 2 whose wavy ridge lines are oriented in a first direction (e.g., the vertical direction) and the partition members 1 on both sides, a plurality of first air flow paths 4 are formed along the first direction. Furthermore, between the spacing member 2 whose wavy ridge lines are oriented in a second direction (e.g., the horizontal direction) and the partition members 1 on both sides, a plurality of second air flow paths 5 are formed along the second direction. Note that arrow 6 in Fig. 1 indicates the direction of air flow in the first air flow path 4, and arrow 7 in Fig. 1 indicates the direction of air flow in the second air flow path 5.

[0054] The spacing members 2 whose wave-shaped ridgelines are oriented in a first direction and the spacing members 2 whose wave-shaped ridgelines are oriented in a second direction are alternately stacked with the ridgelines orthogonal to each other, sandwiching the partition member 1 therebetween, so that the first air flow paths 4 and the second air flow paths 5 are also alternately formed with their extending directions orthogonal to each other. For example, supply air flows through the first air flow path 4, and exhaust air flows through the second air flow path 5, and heat exchange occurs between the supply air and the exhaust air via the partition member 1 and the spacing members 2.

[0055] The method for joining the partition member and the spacing member can be a known method such as a method using an adhesive or a thermal bonding method without using an adhesive. Among these, a method using an adhesive is preferable because it can firmly bond the spacing member and the partition member. Known adhesives such as polyvinyl alcohol adhesives and ethylene vinyl acetate adhesives can be used as the adhesive.

[0056] [Coating Liquid] The present invention provides a coating liquid for producing a partition member for a total heat exchange element, which contains polymeric polysaccharide fine fibers having a fiber width of 1 to 1,000 nm, a binder, and water. The binder is at least one polymer selected from water-soluble polymers and water-dispersible polymers. Details of the polymeric polysaccharide fine fibers and the binder are as described above.

[0057] A preferred embodiment of the present invention is a coating liquid in which the binder is at least one selected from carboxymethyl cellulose and its salts. Furthermore, the binder is preferably an ammonium salt of carboxymethyl cellulose. The coating liquid of the present invention contains fine polymeric polysaccharide fibers having a fiber width of 1 to 1,000 nm and a cellulose derivative having a similar structure as a binder, and therefore can improve adhesion, cohesion, and water resistance while taking advantage of the advantages of the fine polymeric polysaccharide fibers.

[0058] The features of the present invention will be explained in more detail below with reference to examples and comparative examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[0059] [Test Example 1] <Preparation of Sheet-Like Substrate> Substrate A: A 20 μm thick polyethylene film (product name: SW320H, manufactured by Shenzhen Senior Technology Material Co., Ltd.) was prepared as a hydrophobic porous substrate. The surface density was 10.0 g / m ２ Substrate B: A 16 μm thick polypropylene film (product name: SD216301, manufactured by Shenzhen Senior Technology Material Co., Ltd.) was prepared as a hydrophobic porous substrate. The surface density was 9.4 g / m ２ It was.

[0060] <Production of Fine Cellulose Fibers> (Phosphate Group Introduction Step) As a raw material pulp, softwood kraft pulp (solid content 93% by mass, basis weight 210 g / m) manufactured by Oji Paper Co., Ltd. was used. ２ A sheet-like pulp (disintegrated, with a Canadian Standard Freeness (CSF) of 690 ml as measured in accordance with JIS P 8121:2012) was used. This raw pulp was subjected to a phosphating treatment as follows. First, a mixed aqueous solution of ammonium dihydrogen phosphate and urea was added to the raw pulp to adjust the ratio to 45 parts by mass of ammonium dihydrogen phosphate, 120 parts by mass of urea, and 150 parts by mass of water per 100 parts by mass of raw pulp (bone dry mass), thereby obtaining a chemical-impregnated pulp. Next, the obtained chemical-impregnated pulp was heated in a hot air dryer at 165°C for 200 seconds to introduce phosphate groups into the cellulose in the pulp, thereby obtaining a phosphorylated pulp.

[0061] (Washing step) The resulting phosphorylated pulp was then washed. The washing step was carried out by pouring 10 L of ion-exchanged water onto 100 g (bone dry mass) of phosphorylated pulp, stirring to uniformly disperse the pulp, and then repeatedly filtering and dehydrating the pulp. The washing was completed when the electrical conductivity of the filtrate reached 100 μS / cm or less.

[0062] (Alkali Treatment Step) Next, the washed phosphorylated pulp was subjected to an alkali treatment (neutralization treatment) as follows. First, the washed phosphorylated pulp was diluted with 10 L of ion-exchanged water, and then a 1 N aqueous solution of sodium hydroxide was added little by little while stirring to obtain a phosphorylated pulp slurry having a pH of 12 to 13. Next, the phosphorylated pulp slurry was dehydrated to obtain phosphorylated pulp that had been subjected to an alkali treatment (neutralization treatment). Next, the phosphorylated pulp after the alkali treatment was subjected to the above-mentioned washing treatment. The infrared absorption spectrum of the phosphorylated pulp obtained after the alkali treatment was measured using FT-IR. As a result, －１Absorption due to phosphate groups was observed around 2θ = 14° to 17° and 2θ = 22° to 23°, confirming the addition of phosphate groups to the pulp. The amount of phosphate groups (amount of strongly acidic groups) measured using the above-mentioned measurement method was 1.45 mmol / g. The obtained phosphorylated pulp was analyzed using an X-ray diffractometer, and typical peaks for cellulose type I crystals were observed at two positions, around 2θ = 14° to 17° and around 2θ = 22° to 23°, confirming the presence of cellulose type I crystals.

[0063] (Defibrillation Treatment Step) Ion-exchanged water was added to the phosphorylated pulp obtained through the alkali treatment step to prepare a slurry with a solids concentration of 2% by mass. This slurry was treated three times at a pressure of 200 MPa using a wet pulverization device (Starburst, manufactured by Sugino Machine Co., Ltd.) to obtain a microfibrillated cellulose fiber dispersion containing microfibrillated cellulose fibers. X-ray diffraction confirmed that the microfibrillated cellulose fibers maintained cellulose type I crystals. Furthermore, the fiber width of the microfibrillated cellulose fibers was measured using a transmission electron microscope and found to be 3 to 5 nm. Furthermore, the yield of the microfibrillated cellulose fibers obtained was measured according to the method described above, and the yield was 99.2%.

[0064] Example 1 After corona discharge treatment was performed on one surface of the substrate A, a 5% coating solution containing polyvinyl alcohol (trade name: Exeval HR-3010, manufactured by Kuraray Co., Ltd.) and water was applied with a Mayer bar to a coating amount of 0.42 g / m after drying. ２ The coating was then dried at 70°C for 10 minutes to obtain a gas barrier sheet.

[0065] Example 2 After corona discharge treatment was performed on one surface of the substrate A, a 5% coating solution containing polyvinyl alcohol (trade name: Exeval HR-3010, manufactured by Kuraray Co., Ltd.) and water was applied using a Mayer bar to a coating amount of 1.05 g / m after drying. ２ The coating was carried out so that the coating amount became 100% and then dried at 70°C for 10 minutes to obtain a gas barrier sheet.

[0066] (Example 3) One surface of the substrate A was subjected to a corona discharge treatment, and then a coating liquid containing 3 parts by mass of carboxymethyl cellulose (trade name: CMC1110, manufactured by Daicel Miraize Co., Ltd.), 1.2 parts by mass of a polyether surfactant (trade name: SN Wet 985, manufactured by San Nopco Co., Ltd., 76% aqueous dispersion), and 95.8 parts by mass of water was applied using a Mayer bar to a coating amount of 1.16 g / m after drying. ２ The coating was carried out so that the coating amount became 100% and then dried at 70°C for 10 minutes to obtain a gas barrier sheet.

[0067] (Example 4) One surface of the substrate A was subjected to a corona discharge treatment, and then a coating liquid containing 3 parts by mass of carboxymethyl cellulose (trade name: CMC1110, manufactured by Daicel Miraize Co., Ltd.), 1.2 parts by mass of a polyether surfactant (trade name: SN Wet 985, manufactured by San Nopco Co., Ltd., 76% aqueous dispersion), and 95.8 parts by mass of water was applied using a Mayer bar to a coating amount of 0.64 g / m after drying. ２ The coating was carried out so that the coating amount became 100% and then dried at 70°C for 10 minutes to obtain a gas barrier sheet.

[0068] Example 5 One surface of the substrate A was subjected to a corona discharge treatment, and then a coating liquid containing 3 parts by mass of carboxymethyl cellulose ammonium salt (trade name: DN-10L, manufactured by Daicel Millize Co., Ltd.), 1.2 parts by mass of a polyether surfactant (trade name: SN Wet 985, manufactured by San Nopco Co., Ltd., 76% aqueous dispersion), and 95.8 parts by mass of water was applied using a Mayer bar to a coating amount of 0.50 g / m after drying. ２ The coating was carried out so that the coating amount became 100% and then dried at 70°C for 10 minutes to obtain a gas barrier sheet.

[0069] Comparative Example 1 Substrate A was used as it was as a gas barrier sheet.

[0070] (Example 6) One surface of the substrate B was subjected to a corona discharge treatment, and then a coating liquid containing 0.56 parts by mass of carboxymethyl cellulose ammonium salt (trade name: DN-10L, manufactured by Daicel Miraize Co., Ltd.), 18.3 parts by mass of fine cellulose fibers, 0.64 parts by mass of a nonionic surfactant (trade name: Noigen XL-100, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., solid content 100%), and 80.5 parts by mass of water was applied using a Mayer bar to a coating amount of 0.36 g / m after drying.２ The coating was then dried at 105°C for 10 minutes to obtain a gas barrier sheet.

[0071] Comparative Example 2 Substrate B was used as it was as a gas barrier sheet.

[0072] (Evaluation) The moisture permeability and Oken air permeability of the gas barrier sheets obtained in the Examples and Comparative Examples were measured, and the results are shown in Table 1. "Moisture permeability" Measured in accordance with JIS Z0208 under conditions of 20°C and 65% RH. Calculation was performed using the following formula: Moisture permeability = (a + b) / 2, where a = mass increase one hour after the start of measurement, and b = mass increase one hour from one hour after the start of measurement to two hours after the start of measurement.

[0073] "Oken air permeability" Measured in accordance with the Oken air permeability method of JAPAN TAPPI Paper Pulp Test Method No. 5-2:2000.

[0074] "Carbon dioxide gas barrier properties" A measuring device was used, equipped with container A for testing high-concentration CO2 and container B for measuring the CO2 concentration, as 12 cm square partition members. 20,000 ppm of CO2 was sealed in container A under room temperature and normal pressure conditions, and then left for 15 minutes, after which the CO2 concentration in container B was measured using a CO2 analyzer. The amount of CO2 that passed through the partition member in 15 minutes was calculated as the CO2 concentration in container B. When the CO2 concentration in container B was 10,000 ppm or less, the carbon dioxide gas barrier properties of the partition member were judged to be good and rated as ◯, and when the CO2 concentration exceeded 10,000 ppm, it was judged to be poor and rated as ×.

[0075] "Water immersion test" A sample of a partition member for a total heat exchange element cut to A4 size was immersed in 30 liters of tap water. A 120 g weight was attached to the sample to prevent it from floating up. After 10 minutes, the sample was removed and air-dried at room temperature until no water droplets remained on the film surface. (Peeling) The surface of the dried sample was observed to check for peeling of the coating layer. (Oken air permeability (after water immersion)) The Oken air permeability of the dried sample was measured in accordance with the Oken air permeability method of JAPAN TAPPI Paper and Pulp Test Method No. 5-2:2000.

[0076] "Basis Weight" The basis weight of the gas barrier sheet was calculated from the area and mass of the test piece in accordance with JIS P8124:2011.

[0077]

[0078] The gas barrier sheets obtained in each Example had high air permeability and excellent gas barrier properties. The gas barrier sheets using the cellulose derivatives of Examples 3 to 6 had high moisture permeability. In particular, when fine fibers of polymeric polysaccharides with a fiber width of 1 to 1000 nm were used in combination, a gas barrier sheet with high air permeability and high moisture permeability was obtained. Gas barrier sheets with high air permeability and high moisture permeability are suitable for use as partition members for total heat exchange elements.

[0079] [Test Example 2] <Preparation of Substrate> Substrate: A 16 μm thick polypropylene film (product name: SD216301, manufactured by Shenzhen Senior Technology Material Co., Ltd.) was prepared as a hydrophobic porous substrate. The surface density was 9.4 g / m ２ The Oken air permeability was 305 seconds.

[0080] <Preparation of Fine Cellulose Fibers> (Phosphate Group Introduction Step) As a raw material pulp, softwood kraft pulp (solid content 93% by mass, basis weight 210 g / m) manufactured by Oji Paper Co., Ltd. was used. ２ A sheet-like pulp (disintegrated, with a Canadian Standard Freeness (CSF) of 690 ml as measured in accordance with JIS P 8121:2012) was used. This raw pulp was subjected to a phosphating treatment as follows. First, a mixed aqueous solution of ammonium dihydrogen phosphate and urea was added to the raw pulp to adjust the ratio to 45 parts by mass of ammonium dihydrogen phosphate, 120 parts by mass of urea, and 150 parts by mass of water per 100 parts by mass of raw pulp (bone dry mass), thereby obtaining a chemical-impregnated pulp. Next, the obtained chemical-impregnated pulp was heated in a hot air dryer at 165°C for 200 seconds to introduce phosphate groups into the cellulose in the pulp, thereby obtaining a phosphorylated pulp.

[0081] (Washing step) The resulting phosphorylated pulp was then washed. The washing step was carried out by pouring 10 L of ion-exchanged water onto 100 g (bone dry mass) of phosphorylated pulp, stirring to uniformly disperse the pulp, and then repeatedly filtering and dehydrating the pulp. The washing was completed when the electrical conductivity of the filtrate reached 100 μS / cm or less.

[0082] (Alkali Treatment Step) Next, the washed phosphorylated pulp was subjected to an alkali treatment (neutralization treatment) as follows. First, the washed phosphorylated pulp was diluted with 10 L of ion-exchanged water, and then a 1 N aqueous solution of sodium hydroxide was added little by little while stirring to obtain a phosphorylated pulp slurry having a pH of 12 to 13. Next, the phosphorylated pulp slurry was dehydrated to obtain phosphorylated pulp that had been subjected to an alkali treatment (neutralization treatment). Next, the phosphorylated pulp after the alkali treatment was subjected to the above-mentioned washing treatment. The infrared absorption spectrum of the phosphorylated pulp obtained after the alkali treatment was measured using FT-IR. As a result, －１ Absorption due to phosphate groups was observed around 2θ = 14° to 17°, confirming the addition of phosphate groups to the pulp. The amount of phosphate groups (amount of strongly acidic groups) measured using the above-mentioned measurement method was 1.45 mmol / g. The obtained phosphorylated pulp was analyzed using an X-ray diffractometer, and typical peaks for cellulose type I crystals were observed at two positions, around 2θ = 14° to 17° and around 2θ = 22° to 23°, confirming the presence of cellulose type I crystals.

[0083] (Defibrillation Treatment Step) Ion-exchanged water was added to the phosphorylated pulp obtained through the alkali treatment step to prepare a slurry with a solids concentration of 2% by mass. This slurry was treated three times at a pressure of 200 MPa using a wet pulverization device (Starburst, manufactured by Sugino Machine Co., Ltd.) to obtain a microfibrillated cellulose fiber dispersion containing microfibrillated cellulose fibers. X-ray diffraction confirmed that the microfibrillated cellulose fibers maintained cellulose type I crystals. Furthermore, the fiber width of the microfibrillated cellulose fibers was measured using a transmission electron microscope and found to be 3 to 5 nm. Furthermore, the yield of the microfibrillated cellulose fibers obtained was measured according to the method described above, and the yield was 99.2%.

[0084] (Comparative Example 11) <Production of Partition Member for Total Heat Exchange Element> A polyether surfactant (product name: SN Wet 985, manufactured by San Nopco, 76% aqueous dispersion) and water were added to the 0.5% aqueous dispersion of fine cellulose fibers obtained above to prepare a coating liquid. The formulation is shown in the table below as the amount of adhesion of each component. The concentration of the coating liquid was 0.7%. One side of the substrate was subjected to a corona discharge treatment, and then the coating liquid was applied with a Mayer bar to a coating weight of 0.37 g / m after drying. ２ The mixture was dried at 70° C. for 10 minutes to obtain a partition member for a total heat exchange element.

[0085] (Example 11) To the 0.5% aqueous dispersion of fine cellulose fibers obtained above, carboxymethyl cellulose ammonium salt (trade name: DN-10L, manufactured by Daicel Miraize Co., Ltd., 3% solution) and a polyether surfactant (trade name: SN Wet 985, manufactured by San Nopco Co., Ltd., 76% aqueous dispersion) were added to obtain a coating liquid. The formulation is shown in the table below as the amount of adhesion of each component. The concentration of the coating liquid was 0.8%. One side of the substrate was subjected to a corona discharge treatment, and then coated with a Mayer bar until the coating amount after drying was 0.33 g / m. ２ The mixture was dried at 70° C. for 10 minutes to obtain a partition member for a total heat exchange element.

[0086] (Example 12) To the 0.5% aqueous dispersion of fine cellulose fibers obtained above, carboxymethyl cellulose ammonium salt (trade name: DN-10L, manufactured by Daicel Miraize Co., Ltd., 3% solution) and a polyether surfactant (trade name: SN Wet 985, manufactured by San Nopco Co., Ltd., 76% aqueous dispersion) were added to obtain a coating liquid. The formulation is shown in the table below as the amount of adhesion of each component. The concentration of the coating liquid was 0.8%. One side of the substrate was subjected to a corona discharge treatment, and then coated with a Mayer bar until the coating amount after drying was 0.38 g / m. ２ and dried at 105°C for 10 minutes to obtain a partition member for a total heat exchange element. (Evaluation) The moisture permeability and air permeability of the partition members for a total heat exchange element obtained in the examples and comparative examples were measured, and the air permeability after immersion in water and the presence or absence of peeling are shown in Table 2. "Moisture permeability" Measured in accordance with JIS Z0208 under conditions of 20°C and 65% RH. Calculation was made using the following formula: Moisture permeability = (a + b) / 2 where a = mass increase 1 hour after the start of measurement b = mass increase 1 hour from 1 hour after the start of measurement to 2 hours after the start of measurement

[0087] "Oken air permeability" Measured in accordance with the Oken air permeability method of JAPAN TAPPI Paper Pulp Test Method No. 5-2:2000.

[0088] "Water immersion test" A sample of a partition member for a total heat exchange element cut to A4 size was immersed in 30 liters of tap water. A 120 g weight was attached to the sample to prevent it from floating up. After 10 minutes, the sample was removed and air-dried at room temperature until no water droplets remained on the film surface. (Peeling) The surface of the dried sample was observed to check for peeling of the coating layer. (Oken air permeability (after water immersion)) The Oken air permeability of the dried sample was measured in accordance with the Oken air permeability method of JAPAN TAPPI Paper and Pulp Test Method No. 5-2:2000.

[0089] "Basis Weight" The basis weight of the partition member for a total heat exchange element was calculated from the area and mass of the test piece in accordance with JIS P8124:2011.

[0090]

[0091] The partition members for total heat exchange elements obtained in the Examples and Comparative Examples had high air permeability and moisture permeability. When Comparative Example 11, which did not contain a cellulose derivative, was subjected to a water immersion test, peeling occurred in the coating layer and the air permeability also decreased significantly. On the other hand, when the Examples containing a cellulose derivative were subjected to a water immersion test, no peeling occurred in the coating layer and the air permeability decreased, but did not fall below 10,000 seconds. In particular, Example 12, in which the drying temperature was increased, also had high air permeability after water immersion. When such a partition member for total heat exchange elements is used as a total heat exchange element, it can be fully applied even in harsh environments where condensation occurs frequently. Furthermore, a coating liquid containing fine cellulose fibers and a cellulose derivative is a coating liquid that has excellent adhesion and water resistance of the coating layer without impairing the performance of the fine cellulose fibers.

[0092] [Test Example 3] <Preparation of Substrate> Substrate A: A 20 μm thick polyethylene film (product name: SW320H, manufactured by Shenzhen Senior Technology Material Co., Ltd.) was prepared as a hydrophobic porous substrate. The surface density was 10.0 g / m ２ Substrate B: A 16 μm thick polypropylene film (product name: SD216301, manufactured by Shenzhen Senior Technology Material Co., Ltd.) was prepared as a hydrophobic porous substrate. The surface density was 9.4 g / m ２ It was.

[0093] <Preparation of Fine Cellulose Fibers> (Phosphate Group Introduction Step) As a raw material pulp, softwood kraft pulp (solid content 93% by mass, t 210 g / m) manufactured by Oji Paper Co., Ltd. was used. ２A sheet-like pulp (disintegrated, with a Canadian Standard Freeness (CSF) of 690 ml as measured in accordance with JIS P 8121:2012) was used. This raw pulp was subjected to a phosphating treatment as follows. First, a mixed aqueous solution of ammonium dihydrogen phosphate and urea was added to the raw pulp to adjust the ratio to 45 parts by mass of ammonium dihydrogen phosphate, 120 parts by mass of urea, and 150 parts by mass of water per 100 parts by mass of raw pulp (bone dry mass), thereby obtaining a chemical-impregnated pulp. Next, the obtained chemical-impregnated pulp was heated in a hot air dryer at 165°C for 200 seconds to introduce phosphate groups into the cellulose in the pulp, thereby obtaining a phosphorylated pulp.

[0094] (Washing step) The resulting phosphorylated pulp was then washed. The washing step was carried out by pouring 10 L of ion-exchanged water onto 100 g (bone dry mass) of phosphorylated pulp, stirring to uniformly disperse the pulp, and then repeatedly filtering and dehydrating the pulp. The washing was completed when the electrical conductivity of the filtrate reached 100 μS / cm or less.

[0095] (Alkali Treatment Step) Next, the washed phosphorylated pulp was subjected to an alkali treatment (neutralization treatment) as follows. First, the washed phosphorylated pulp was diluted with 10 L of ion-exchanged water, and then a 1 N aqueous solution of sodium hydroxide was added little by little while stirring to obtain a phosphorylated pulp slurry having a pH of 12 to 13. Next, the phosphorylated pulp slurry was dehydrated to obtain phosphorylated pulp that had been subjected to an alkali treatment (neutralization treatment). Next, the phosphorylated pulp after the alkali treatment was subjected to the above-mentioned washing treatment. The infrared absorption spectrum of the phosphorylated pulp obtained after the alkali treatment was measured using FT-IR. As a result, －１Absorption due to phosphate groups was observed around 2θ = 14° to 17° and 2θ = 22° to 23°, confirming the addition of phosphate groups to the pulp. The amount of phosphate groups (amount of strongly acidic groups) measured using the above-mentioned measurement method was 1.45 mmol / g. The obtained phosphorylated pulp was analyzed using an X-ray diffractometer, and typical peaks for cellulose type I crystals were observed at two positions, around 2θ = 14° to 17° and around 2θ = 22° to 23°, confirming the presence of cellulose type I crystals.

[0096] (Defibrillation Treatment Step) Ion-exchanged water was added to the phosphorylated pulp obtained through the alkali treatment step to prepare a slurry with a solids concentration of 2% by mass. This slurry was treated three times at a pressure of 200 MPa using a wet pulverization device (Starburst, manufactured by Sugino Machine Co., Ltd.) to obtain a microfibrillated cellulose fiber dispersion containing microfibrillated cellulose fibers. X-ray diffraction confirmed that the microfibrillated cellulose fibers maintained cellulose type I crystals. Furthermore, the fiber width of the microfibrillated cellulose fibers was measured using a transmission electron microscope and found to be 3 to 5 nm. Furthermore, the yield of the microfibrillated cellulose fibers obtained was measured according to the method described above, and the yield was 99.2%.

[0097] Comparative Example 21 The substrate A was used as it was as a partition member for a total heat exchange element.

[0098] (Example 21) A coating liquid containing carboxymethyl cellulose (trade name: CMC1110, manufactured by Daicel Miraize Co., Ltd.), a polyether surfactant (trade name: SN Wet 985, manufactured by San Nopco Co., Ltd., 76% aqueous dispersion), and water was obtained. The formulation is shown in the table below as the amount of adhesion of each component. The coating liquid concentration was 3.9%. One side of the above substrate A was subjected to a corona discharge treatment, and then the coating liquid was applied with a Mayer bar until the coating amount after drying was 0.66 g / m. ２ The mixture was dried at 70° C. for 10 minutes to obtain a partition member for a total heat exchange element.

[0099] Example 22 A coating liquid containing carboxymethyl cellulose ammonium salt (trade name: DN-10L, manufactured by Daicel Miraize Co., Ltd.), a polyether surfactant (trade name: SN Wet 985, manufactured by San Nopco Co., Ltd., 76% aqueous dispersion), and water was obtained. The formulation is shown in the table below as the amount of adhesion of each component. The concentration of the coating liquid was 3.9%. One side of the above substrate A was subjected to a corona discharge treatment, and then the coating liquid was applied with a Mayer bar to a coating amount of 0.50 g / m after drying. ２ The mixture was dried at 70° C. for 10 minutes to obtain a partition member for a total heat exchange element.

[0100] (Comparative Example 23) Substrate B was used as it is as a partition member for a total heat exchange element. (Example 23) <Production of Partition Member for Total Heat Exchange Element> A polyether surfactant (product name: SN Wet 985, manufactured by San Nopco, 76% aqueous dispersion) and water were added to the 0.5% aqueous dispersion of fine cellulose fibers obtained above to prepare a coating liquid. The formulation is shown in the table below as the adhesion amount of each component. The coating liquid concentration was 0.72%. One side of the substrate B was subjected to a corona discharge treatment, and then the coating liquid was applied with a Mayer bar to a coating amount of 0.37 g / m after drying. ２ The mixture was dried at 70° C. for 10 minutes to obtain a partition member for a total heat exchange element.

[0101] (Example 24) A coating liquid was obtained by adding carboxymethyl cellulose ammonium salt (trade name: DN-10L, manufactured by Daicel Millize Co., Ltd.), a polyether surfactant (trade name: SN 985, manufactured by San Nopco Co., Ltd., 76% aqueous dispersion), and water. The formulation is shown in the table below as the amount of adhesion of each component. The concentration of the coating liquid was 3.9%. One side of the above substrate B was subjected to a corona discharge treatment, and then coated with a Mayer bar until the coating amount after drying was 0.57 g / m. ２ The mixture was dried at 105° C. for 10 minutes to obtain a partition member for a total heat exchange element.

[0102] (Example 25) To the 0.5% aqueous dispersion of fine cellulose fibers obtained above, carboxymethyl cellulose ammonium salt (trade name: DN-10L, manufactured by Daicel Miraize Co., Ltd., 3% solution), a polyether surfactant (trade name: SN Wet 985, manufactured by San Nopco Co., Ltd., 76% aqueous dispersion), and water were added to obtain a coating liquid. The formulation is shown in the table below as the amount of adhesion of each component. The concentration of the coating liquid was 0.77%. One side of the above substrate B was subjected to a corona discharge treatment, and then coated with a Mayer bar until the coating amount after drying was 0.50 g / m. ２ The mixture was dried at 105° C. for 10 minutes to obtain a partition member for a total heat exchange element.

[0103] (Example 26) To the 0.5% aqueous dispersion of fine cellulose fibers obtained above, carboxymethyl cellulose ammonium salt (trade name: DN-10L, manufactured by Daicel Miraize Co., Ltd., 3% solution), a polyether surfactant (trade name: SN Wet 985, manufactured by San Nopco Co., Ltd., 76% aqueous dispersion), and water were added to obtain a coating liquid. The formulation is shown in the table below as the amount of adhesion of each component. The concentration of the coating liquid was 1.6%. One side of the above substrate B was subjected to a corona discharge treatment, and then coated with a Mayer bar until the coating amount after drying was 0.45 g / m ２ The mixture was dried at 105° C. for 10 minutes to obtain a partition member for a total heat exchange element.

[0104] (Evaluation) The moisture permeability and Oken air permeability of the partition members for total heat exchange elements obtained in the examples and comparative examples were measured and are shown in the following tables. In addition to the moisture permeability and Oken air permeability, Tables 4 and 5 also show the Oken air permeability after immersion in water.

[0105] "Moisture permeability" Measured in accordance with JIS Z0208 under conditions of 20°C and 65% RH. Calculation was made using the following formula: Moisture permeability = (a + b) / 2, where a = mass increase one hour after the start of measurement, and b = mass increase one hour from one hour after the start of measurement to two hours after the start of measurement.

[0106] "Oken air permeability" Measured in accordance with the Oken air permeability method of JAPAN TAPPI Paper Pulp Test Method No. 5-2:2000.

[0107] "Water immersion test" A sample of a partition member for a total heat exchange element cut to A4 size was immersed in 2 liters of tap water. A 120 g weight was attached to the sample to prevent it from floating up. After 10 minutes, the sample was removed and air-dried at room temperature until no water droplets remained on the film surface. (Oken air permeability (after water immersion)) The Oken air permeability of the dried sample was measured in accordance with the Oken air permeability method of JAPAN TAPPI Paper and Pulp Test Method No. 5-2:2000.

[0108] "Basis Weight" The basis weight of the partition member for a total heat exchange element was calculated from the area and mass of the test piece in accordance with JIS P8124:2011.

[0109]

[0110]

[0111]

[0112] The partition members for total heat exchange elements obtained in the examples were lightweight yet had high air permeability and moisture permeability. Example 23, which used fine cellulose fibers, tended to have a decrease in air permeability after immersion in water. Example 24, which used a cellulose derivative, did not have a decrease in air permeability after immersion in water, but tended to have slightly inferior moisture permeability. Examples 25 and 26, which used a combination of fine cellulose fibers and a cellulose derivative, were less affected by the decrease in air permeability after immersion in water and also had high moisture permeability.

[0113] REFERENCE SIGNS LIST 1 Partition member 2 Spacing member 4 First air flow path 5 Second air flow path 10 Total heat exchange element

Claims

1. A partition member for a total heat exchange element, comprising a sheet-like substrate and a coating layer on at least one side thereof, the coating layer containing a binder or fine fibers of a polymeric polysaccharide having a fiber width of 1 to 1,000 nm, the binder being at least one polymer selected from water-soluble polymers and water-dispersible polymers.

2. A partition member for a total heat exchange element according to claim 1, wherein the coating layer contains fine fibers of high molecular weight polysaccharides having a fiber width of 1 to 1000 nm and a binder.

3. The partition member for a total heat exchange element according to claim 2, wherein the binder is a cellulose derivative.

4. The partition member for a total heat exchange element according to claim 2, wherein the binder is at least one selected from the group consisting of carboxymethyl cellulose and salts thereof.

5. The partition member for a total heat exchange element according to claim 2, wherein the binder is an ammonium salt of carboxymethyl cellulose.

6. A partition member for a total heat exchange element according to claim 2, wherein the fine fibers are chemically modified fine cellulose fibers.

7. The partition member for a total heat exchange element according to claim 1, wherein the sheet-like substrate is a hydrophobic porous substrate.

8. A partition member for a total heat exchange element according to claim 1, wherein the sheet-like substrate has an Oken air permeability of 1000 seconds or less.

9. The partition member for a total heat exchange element according to claim 1, wherein the thickness of the sheet-like substrate is 5 μm or more and 30 μm or less.

10. The coating amount of the coating layer is 0.03 g / m ２ 3g / m or more ２ The partition member for a total heat exchange element according to claim 1 , wherein:

11. A partition member for a total heat exchange element according to claim 1, having an Oken air permeability of 10,000 seconds or more.

12. Moisture permeability at a temperature of 20°C and a relative humidity of 65% is 2500 g / m ２ The partition member for a total heat exchange element according to claim 1, wherein the heat exchanger has a life of 24 hours or more.

13. Basis weight: 5 to 30 g / m ２ The partition member for a total heat exchange element according to claim 1, wherein 14. A partition member for a total heat exchange element according to claim 1, which has an Oken air permeability of 10,000 seconds or more under conditions of 20°C and a relative humidity of 65% after undergoing the following water immersion test: "Water immersion test" The partition member for a total heat exchange element is cut into an A4 size sample and immersed in 30 liters of tap water. After 10 minutes, the sample is removed and air-dried at room temperature until no water droplets remain on the film surface.

15. A total heat exchange element comprising a plurality of partition members for total heat exchange elements according to any one of claims 1 to 14, and spacing members arranged between the partition members for total heat exchange elements to maintain the spacing between adjacent partition members for total heat exchange elements, wherein first air flow paths and second air flow paths are formed alternately with the partition members for total heat exchange elements sandwiched therebetween.

16. A method for manufacturing a partition member for a total heat exchange element, comprising the steps of applying a coating liquid containing a binder or fine fibers of a polymeric polysaccharide having a fiber width of 1 to 1000 nm and water to at least one surface of a sheet-like substrate, and then drying the coating liquid, wherein the binder is at least one polymer selected from water-soluble polymers and water-dispersible polymers.

17. The method for producing a partition member for a total heat exchange element according to claim 16, wherein the coating liquid contains fine fibers of a high molecular weight polysaccharide having a fiber width of 1 to 1000 nm, a binder, and water.

18. The method for producing a partition member for a total heat exchange element according to claim 17, wherein the binder is a cellulose derivative.

19. The method for producing a partition member for a total heat exchange element according to claim 17, wherein the binder is at least one selected from the group consisting of carboxymethyl cellulose and salts thereof.

20. The method for producing a partition member for a total heat exchange element according to claim 17, wherein the binder is an ammonium salt of carboxymethyl cellulose.

21. The method for producing a partition member for a total heat exchange element according to claim 17, wherein the fine fibers are chemically modified fine cellulose fibers.

22. The method for producing a partition member for a total heat exchange element according to claim 16, wherein the sheet-like substrate is a hydrophobic porous substrate.

23. The method for manufacturing a partition member for a total heat exchange element according to claim 16, wherein the drying temperature in the drying step is 70°C or higher and 130°C or lower.

24. A coating solution for manufacturing a partition member for a total heat exchange element, comprising fine fibers of a polymeric polysaccharide having a fiber width of 1 to 1000 nm, a binder, and water, wherein the binder is at least one polymer selected from the group consisting of water-soluble polymers and water-dispersible polymers.

25. The coating liquid for producing a partition member for a total heat exchange element according to claim 24, wherein the binder is a cellulose derivative.

26. The coating solution for producing a partition member for a total heat exchange element according to claim 24, wherein the binder is at least one selected from the group consisting of carboxymethyl cellulose and salts thereof.

27. The coating liquid for producing a partition member for a total heat exchange element according to claim 24, wherein the binder is an ammonium salt of carboxymethyl cellulose.

28. The coating liquid for producing a partition member for a total heat exchange element according to claim 24, wherein the fine fibers are chemically modified fine cellulose fibers.

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