JP2020147872A - Total heat exchange element sheet, and total heat exchange element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a total heat exchange element paper having excellent moisture permeability, thermal conductivity, strength, gas shielding property and deodorizing property.
SOLUTION: The base sheet contains activated charcoal and natural pulp, and the length-weighted average fiber length of the natural pulp is 0.7 to 1.7 mm, and in the fiber length histogram of the natural pulp, 0.5. The ratio of fibers having a maximum frequency peak between ~ 1.5 mm and a fiber length of 1.0 mm or more is 25.0% or more, and the content of activated carbons with respect to the total heat exchange element paper is high. Total heat exchange element paper of 5 to 30% by mass.
[Selection diagram] Fig. 1

Description

The present invention is installed in a total heat exchanger that supplies fresh outside air to the room and discharges dirty air in the room in order to maintain a comfortable space in buildings, offices, stores, residences, etc. The present invention relates to a total heat exchange element that exchanges sensible heat (temperature) and latent heat (humidity) at the same time, and a total heat exchange element paper used for the total heat exchange element.

In indoor air conditioning, as a ventilation method with excellent cooling and heating efficiency, exchange of humidity (latent heat) as well as temperature (sensible heat) between the air supply that supplies fresh outside air and the exhaust flow that discharges dirty air in the room. It is well known that total heat exchange is performed at the same time.

In the total heat exchange element that performs total heat exchange, the supply airflow and the exhaust flow are formed in independent flow paths with the total heat exchange element paper in between, and total heat exchange is performed between them. If the room is ventilated with a total heat exchanger equipped with a total heat exchange element, the cooling and heating efficiency can be greatly suppressed.

There are two types of total heat exchange elements, a orthogonal flow type and a countercurrent type, which are produced by processing total heat exchange element paper. Both are created using a dedicated machine, but especially in the case of the countercurrent type, the process of attaching a resin frame to secure the flow path for passing indoor and outdoor air to the total heat exchange element paper is is there. Generally, an injection molding machine is used from the viewpoint of work efficiency. At this time, if the strength of the total heat exchange element paper is insufficient, the total heat exchange element paper is torn by the pressure of the injected resin, and all It does not function at all as a heat exchange element.

Further, since the conventional total heat exchange element paper uses a porous material, for example, it also has air permeability of a dirty gas component such as carbon dioxide, and air is supplied when total heat exchange is performed. And the exhaust are mixed inside the total heat exchange element, which has the disadvantage of reducing the efficiency of ventilation. This mixture of air supply and exhaust is a fatal defect for total heat exchangers. In a total enthalpy heat exchanger in which air supply and exhaust are mixed, it may be evaluated that the air inside and outside the room is not exchanged while being recovered by energy, but simply agitating the dirty air in the room. In this way, if the indoor and outdoor air seems to be mixed, the purpose of ventilation cannot be achieved and the total heat exchanger cannot function at all.

For this reason, the total heat exchange element paper has excellent strength so that the total heat exchange element paper does not tear when the total heat exchange element is manufactured, and the total heat exchange element paper has excellent gas shielding properties so that air supply and exhaust do not mix. Is required. In response to such demands, binders and melts are applied to the surface of a non-woven fabric or woven fabric sheet base material made of glass fiber, synthetic fiber, natural fiber, etc. having a fiber diameter of 0.3 to 50 μm and a thickness of 0.1 to 1.0 mm. A sheet member (for example, Patent Document 1) in which an adhesive medium of fibers or adhesive powder is attached, and a thin layer of ultrafine fibers having a fiber diameter of 0.01 to 0.5 μm is layered, dried and fixed, and integrated. It is disclosed. However, although the strength of the sheet base material can be maintained, there is a problem in terms of economy, and no effect is observed in terms of moisture permeability, heat conductivity and gas shielding property.

Further, the fiber substrate is parchmenting, and a hygroscopic agent contained in said fiber substrate, and is moisture permeability 1000 g / m 2 ^· 24 hr or more moisture permeability sheets (e.g., Patent Document 2) Is disclosed. However, there was room for improvement in thermal conductivity, strength of the fiber substrate, and gas shielding property. Further, a total heat exchange element paper (for example, Patent Document 3) made of paper containing natural pulp beaten to 150 ml or less in a modified Canadian filtrate is disclosed. However, although there is no problem with gas shielding property, sufficient strength of the base material could not be obtained.

Further, it is made of a paper base material mainly composed of pulp, and the paper base material contains 10 to 25% by mass of calcium chloride and has a moisture absorption rate of 15 to 30% (for example, a base paper for a total heat exchanger element). , Patent Document 4) is disclosed. However, there was room for improvement in achieving both strength and gas shielding properties. In addition, a total heat exchange element in which a base paper made of wood pulp in which 100 parts by mass of wood pulp is 40 parts by mass or more and the degree of beating at shopper freedom is 40 ° SR or more is impregnated with a moisture absorbent and a flameproofing agent. a paper, with a moisture permeability by moisture permeability test according to JIS Z-0208 of該全heat exchange element sheets 6,000g ^{/ m} 2 · 24 hours or more, carbide by flame test according to JIS Z-2150 Total heat exchange element paper (for example) having a length of 10 cm or less, an air permeability according to a JIS P-8117 air permeability test of 500 seconds / 100 ml or more, and a carbon dioxide transfer rate of 1% or less. , Patent Document 5) is disclosed. However, there was room for improvement in achieving both strength and gas shielding properties.

By the way, in China, where the economy has grown rapidly, air pollution has become a serious problem, especially in urban areas and the surrounding areas. The wind direction is also affecting the countries around China, and the severity is increasing year by year. Air pollution can occur throughout the year, but the use of indoor heating tends to cause particularly serious air pollution from autumn to winter, when weather conditions tend to deteriorate. When air pollution becomes serious, dirty outside air is supplied to the room when the air conditioner is ventilated. Therefore, a total heat exchanger capable of removing pollutants from the outside air is required. For example, as in Patent Document 1, a total heat exchanger containing a deodorant has been proposed because it can remove contaminants. However, unless the total heat exchanger uses total heat exchange element paper with excellent gas shielding properties, the supply air and exhaust will be mixed inside the total heat exchange element, and the deodorizing performance will not be fully exhibited. Improvement is required.

Japanese Unexamined Patent Publication No. 2011-237157 Japanese Unexamined Patent Publication No. 2016-108704 International Publication No. 2002/099193 Pamphlet Japanese Patent No. 4736718 Japanese Patent No. 4401240

An object of the present invention is to provide a total heat exchange element paper having excellent moisture permeability, thermal conductivity, strength, gas shielding property, and deodorizing property in the total heat exchange element paper for forming an element for a total heat exchanger. That is.

The problem according to the present invention can be solved by the following means.

(1) In the total heat exchange element paper containing the base material sheet, the base material sheet contains activated charcoal and natural pulp, and the length-weighted average fiber length of the natural pulp is 0.7 to 1.7 mm. In the fiber length histogram of the natural pulp, the ratio of fibers having a maximum frequency peak between 0.5 and 1.5 mm and a fiber length of 1.0 mm or more is 25.0% or more, and the total. A total heat exchange element paper characterized in that the content of activated carbons is 5 to 30% by mass with respect to the heat exchange element paper.
(2) The total heat exchange element paper according to (1) above, which has a peak between 0.0 and 0.5 mm in addition to the maximum frequency peak in the fiber length histogram of natural pulp.
(3) A total heat exchange element formed by using the total heat exchange element paper according to (1) or (2) above.

The total heat exchange element paper of the present invention is a total heat exchange element paper containing a base sheet, in which the base sheet contains activated charcoal and natural pulp, and the length-weighted average fiber length of the natural pulp is 0. In the fiber length histogram of the natural pulp, which is .7 to 1.7 mm, the proportion of fibers having the maximum frequency peak between 0.5 and 1.5 mm and having a fiber length of 1.0 mm or more is 25. It is 0% or more, the content of activated carbons is 5 to 30% by mass with respect to the total heat exchange element paper, the fibers of natural pulp are entangled, and the activated carbons are contained in the total heat exchange element paper. As a result, the moisture permeability, thermal conductivity, strength, gas shielding property, and deodorizing property of the total heat exchange element can be improved.

Further, in the fiber length histogram of natural pulp, the total heat exchange element paper having a peak between 0.0 and 0.5 mm in addition to the maximum frequency peak has finer fibers between the fibers without impairing the strength. By closing the gap, it has better gas shielding property that does not cause mixing of air supply and exhaust.

This is an example of a fiber length histogram of natural pulp having a peak between 0.0 and 0.5 mm in addition to the maximum frequency peak and the maximum frequency peak between 0.5 and 1.5 mm.

Hereinafter, the total heat exchange element paper of the present invention will be described in detail.

The base material sheet in the total heat exchange element paper of the present invention will be described. The base material sheet in the present invention is preferably a sheet produced by a wet papermaking method using natural pulp as a raw material. As natural pulp, broad-leaved bleached kraft pulp (abbreviation: LBKP, English notation: Hardwood Bleached Kraft Pulp), coniferous bleached kraft pulp (abbreviation: NBKP, English notation: Softwood Bleached Craft Pulp), broad-leaved bleached kraft pulp , English notation: Hardwood Bleached Sulfite Pulp), bleached coniferous sulphite pulp (abbreviation: NBSP, English notation: Softwood Bleached Sulfite Pulp), broadleaf tree unbleached craft pulp (abbreviation: LUKP, unbleached kraft pulp) It is preferable to use wood pulp fibers such as bleached kraft pulp (abbreviation: NUKP, English notation: Softwood Unbleached Craft Pulp) alone or in combination of two or more. In addition, plant fibers such as cotton, cotton linter, hemp, bamboo, sugar cane, corn, and kenaf; animal fibers such as wool and silk; and cellulose regenerated fibers such as rayon, cupra, and lyocell should be used alone or in combination. You can also.

In the present invention, as shown in FIG. 1, in the fiber length distribution histogram of natural pulp, the ratio having the maximum frequency peak between 0.5 and 1.5 mm and the fiber length of 1.0 mm or less is 25. It is 0.0% or more. In the process of producing a total heat exchange element from the total heat exchange element paper, by entwining fibers of 1.0 mm or more, the strength of the total heat exchange element paper is increased and the gas shielding property is also improved. The maximum frequency peak is more preferably between 0.7 and 1.2 mm. More preferably, the proportion having a fiber length of 1.0 mm or more is 35.0% or more. The proportion of fibers having a fiber length of 1.0 mm or more is preferably high in terms of increasing strength, but about 60% is sufficient.

Further, in the fiber length histogram of natural pulp, the total heat exchange element paper having a peak (second peak) between 0.0 and 0.5 mm in addition to the maximum frequency peak has finer fibers between the fibers. By closing the gap, it has excellent gas shielding properties that do not cause mixing of air supply and exhaust while maintaining strength.

The fiber length and fiber length distribution histogram of the natural pulp of the present invention is based on JIS P8226: 2006 (polarization method) "Pulp-Fiber length measurement method by optical automatic analysis method", and OpTest Equipment Inc. The measurement was performed using a fiber quality analyzer manufactured by Canada.

The "fiber length", "average fiber length" and "fiber length distribution" in the present invention are "length-weighted fiber length", "length-weighted average fiber length" and "length-weighted" measured and calculated according to the above. It means "fiber length distribution". Further, the "ratio of fibers having a fiber length of 1.0 mm or more" means the "ratio of fibers having a fiber length of 1.0 mm or more", and in the "length-weighted fiber length distribution" measured and calculated according to the above. It means the numerical value obtained from the "ratio of fibers of 1.0 mm or more".

Natural pulp is subjected to shearing force by beater, PFI mill, single disc refiner (SDR), double disc refiner (DDR), ball mill, dyno mill, grinder, and high-speed rotary blade used for dispersing and crushing pigments and the like. Rotary blade homogenizer, double cylindrical high speed homogenizer that generates shear force between a cylindrical inner blade that rotates at high speed and a fixed outer blade, an ultrasonic crusher that pulverizes by impact by ultrasonic waves, Examples thereof include a high-pressure homogenizer that applies a shearing force and a cutting force to the fibers by applying a pressure difference of at least 20 MPa to the fiber suspension to pass through a small-diameter orifice to increase the speed, and then colliding the fiber suspension to make a sudden deceleration. .. Of these, the refiner is particularly preferable. By adjusting these beating, the type of dispersion equipment, and the treatment conditions (fiber concentration, temperature, pressure, rotation speed, shape of the refiner blade, gap between the refiner plates, number of treatments), the fiber length distribution of the target natural pulp can be obtained. It will be possible to achieve.

Examples of the method for producing a base sheet in the total heat exchange element paper of the present invention include a wet paper making method in which natural pulp is formed into a sheet using a general long net paper machine, a circular net paper machine, or the like.

The total heat exchange element paper of the present invention contains activated carbons. Examples of activated carbons include activated carbons and impregnated activated carbons. The shape of the activated carbon is not particularly limited, but powder, particle, fibrous, etc. are preferable, and activated carbon having a specific surface area of 50 to 2000 m ² / g can be appropriately selected and used. ..

The particle size of the activated carbons in the present invention is not particularly limited as long as it can be uniformly contained in the total heat exchange element paper, but is preferably 1 to 180 μm, and is preferably 3 to 150 μm. More preferably, it is more preferably 3 to 100 μm. If the particle size exceeds 180 μm, there may be a problem that the particle size is not uniformly contained in the total heat exchange element paper due to precipitation when mixed with the pulp raw material or in the coating liquid. On the other hand, if the particle size is less than 1 μm, the surface area of the activated carbon may increase and it may be difficult to disperse. In the present invention, the particle size of activated carbon is an average particle size that can be measured by a particle size distribution measuring device based on a laser diffraction / scattering method. The laser diffraction type particle size distribution measuring device is not particularly limited, but any device may be used as long as it complies with the laser diffraction method ISO 13320 and JIS Z 8825: 2013. For example, the SALD (registered trademark) series of Shimadzu Corporation can be used.

In the present invention, in order to obtain higher thermal conductivity and deodorizing property, the content of activated carbon is preferably 5 to 30% by mass, preferably 7 to 25% by mass, based on the total heat exchange element paper. More preferably, it is more preferably 10 to 20% by mass. If the content of activated carbon is less than 5% by mass, the expected thermal conductivity and deodorizing property may not be obtained, while if the content exceeds 30% by mass, activated carbon from the total heat exchange element paper. May cause problems such as dropping out.

Since the total heat exchange element paper contains activated carbon, it is possible to impart unpleasant odor deodorizing performance to the total heat exchange element paper. Activated carbons can adsorb and remove odors that can be harmful to the indoor environment, such as volatile organic compounds and unpleasant living odors. In addition, carbon contained in activated carbon has a better thermal conductivity than natural pulp contained in a base sheet. Therefore, the total heat exchange element paper containing activated carbon can be expected to have excellent thermal conductivity. The activated carbons of the present invention can be used alone or in combination of two or more.

The method for containing activated carbon in the total heat exchange element paper is not particularly limited as long as the component can be contained in the total heat exchange element paper as uniformly as possible. A method of mixing a pulp raw material and activated carbon to produce a base sheet, a coating liquid containing activated carbon is applied to the base sheet by a method such as coating, impregnation, or spraying, and the solvent or dispersion medium is dried. Examples thereof include a method of removing activated carbon by the above method and incorporating activated carbon into the total heat exchange element paper.

When the activated carbon is firmly adhered to the total heat exchange element paper, or when the appearance of the product is improved by using it in combination with other components or coloring, a small amount of activated carbon is used as long as the effect of the activated carbon is not impaired. Using a binder (adhesive) is one of the preferred methods. Specific examples of the aqueous binder will be given. Examples of the water-soluble binder include polyvinyl alcohol and starch. Examples of the water-dispersible binder include poly (meth) acrylic acid esters, polyvinyl acetate, polyvinyl chloride, and styrene-butadiene latex.

In order to obtain the required density, smoothness, and moisturizing properties, the base sheet contains various chemicals such as organic pigments, adhesives, sizing agents, fixing agents, yield aids, and paper strength enhancers. Can be appropriately contained.

The base sheet may be surface-sized with a size press, roll coater, or the like installed in a paper machine in order to obtain the required density, smoothness, air permeability, and strength. The components of the surface size press solution include starch purified from natural plants, hydroxyethylated starch, oxidized starch, etherified starch, phosphoric acid esterified starch, enzyme-modified starch and cold water-soluble starch obtained by flush-drying them. Various synthetic binders such as polyvinyl alcohol can be appropriately used.

The substrate sheet may be calendared to obtain the required density, smoothness, air permeability and strength. As the calendar device, a device having one or more combination rolls selected from the group consisting of hard rolls, elastic rolls, and a combination of hard rolls and elastic rolls is preferably used. Specifically, a machine calendar, a soft nip calendar, a super calendar, a multi-stage calendar, a multi-nip calendar, or the like can be used.

The total heat exchange paper is not particularly limited in terms of basis weight, thickness, density, etc., but from the viewpoint of exchange efficiency, it is preferable that the basis weight is low, the thickness is thin, and the density is high. The basis weight is preferably in the range of 30~130g / ^{m 2,} the range of 40 and 80 g / ^{m 2} is more preferable. The thickness is preferably in the range of 30 to 120 μm, more preferably in the range of 40 to 100 μm. Density is preferably in the range of 0.7 to 1.3 g / cm ^3, a range of 0.8~1.1g / cm ³ is more preferable.

A flame retardant can be attached to the total heat exchange element paper for the purpose of imparting flame retardancy. Examples of the flame retardant include an inorganic flame retardant, an inorganic phosphorus compound, a nitrogen-containing compound, a chlorine compound, and a bromine compound. For example, a mixture of boric acid and boric acid, aluminum hydroxide, antimony trioxide, ammonium phosphate, ammonium polyphosphate, ammonium sulfamate, guanidine sulfamate, guanidine phosphate, phosphate amide, chlorinated polyolefin, ammonium bromide, Examples thereof include a flame retardant that can be dispersed in an aqueous solution such as a non-ether type polybromocyclic compound or water. As for the level of flame retardancy, it is preferable that the carbonization length measured by JIS A 1322: 1966 is less than 10 cm. The coating weight of the flame retardant is not particularly limited, depending on the flame retardant to be used is preferably in the range of ^{5g / m 2 ~10g / m 2} . More than 10 g / m ² may be attached, but the effect will level off.

An antifungal agent can be attached to the total heat exchange element paper for the purpose of imparting antifungal properties. As the fungicide, commercially available fungicide can be generally used. Examples thereof include organic nitrogen compounds, sulfur compounds, organic acid esters, organic iodine imidazole compounds, and benzazole compounds. As the level of antifungal property, it is preferable that the growth of hyphae measured by JIS Z 2911: 2010 is not observed. The adhesion amount of antifungal agent is preferably in the range of ^{0.5g / m 2 ~5g / m 2} . More than 5 g / m ² may be attached, but the effect will level off.

A hygroscopic agent can be attached to the total heat exchange element paper for the purpose of improving the humidity exchange efficiency. Examples of the hygroscopic agent include inorganic acid salts, organic acid salts, inorganic fillers, polyhydric alcohols, ureas, and hygroscopic (water-absorbing) polymers. For example, examples of the inorganic acid salt include lithium chloride, calcium chloride, magnesium chloride and the like. Examples of the organic acid salt include sodium lactate, calcium lactate, sodium pyrrolidone carboxylate and the like. Examples of the inorganic filler include aluminum hydroxide, calcium carbonate, aluminum silicate, magnesium silicate, talc, clay and the like. Examples of the polyhydric alcohol include glycerin, ethylene glycol, triethylene glycol, polyglycerin and the like. Examples of ureas include urea and hydroxyethyl urea. Examples of the moisture-absorbing (water-absorbing) polymer include polyaspartic acid, polyacrylic acid, polyglutamic acid, polylysine, alginic acid, carboxymethyl cellulose, hydroxyalkyl cellulose and their salts or crosslinked products, carrageenan, pectin, gellan gum, agar, xanthan gum, hyaluron. Acids, guar gum, gum arabic, starch and their crosslinked products, polyethylene glycol, polypropylene glycol, collagen, acrylic nitrile polymer saponification, starch / acrylate graft copolymer, vinyl acetate / acrylate copolymer ken Compounds, starch / acrylic nitrile graft copolymer, acrylate / acrylamide copolymer, polyvinyl alcohol / maleic anhydride copolymer, polyethylene oxide-based, isobutylene / maleic anhydride copolymer, polysaccharide / acrylate graft There are self-crosslinked bodies and the like. It is used by selecting the type and the amount of adhesion according to the target moisture permeability. From the viewpoint of cost and moisture permeability, it is preferable to use one or more hygroscopic agents selected from the group of calcium chloride, lithium chloride and magnesium chloride. A particularly preferred hygroscopic agent is calcium chloride. Calcium chloride may be used in combination with other hygroscopic agents.

The amount of the hygroscopic agent attached is not particularly limited. Depending on the type of desiccant to be used, JIS Z 0208: using the evaluation method 1976, 23 ° C., moisture permeability measured at 50% relative humidity is 300g ^{/ m} 2 · 24 hours or more Is preferable. Within this range, a total heat exchange element having excellent wet heat exchange performance can be obtained. The amount of hygroscopic agent adhering depends on the type of hygroscopic agent used, but the moist heat exchange performance may reach a plateau from a certain amount of adhering agent, and may be in the range of ² g / m ^{2 to} 15 g / m ^{2. preferably,} and more preferably in the range of ^{4g / m 2 ~10g / m 2} . It is preferably in the range of 300g ^{/ m} 2 · 24 hours ~1500g / m2 · 24 hours as moisture permeability, the range of 400g ^{/ m} 2 · 24 hours ~1000g ^{/ m} 2 · 24 hours is more preferable.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the Examples. Unless otherwise specified, "%" and "part" in the examples represent "mass%" and "parts by mass", respectively.

[Preparation Example 1]
Commercially available powdered coconut shell activated carbon (particle size 40 to 100 μm) is stirred in water at a concentration of 30%. A commercially available acrylic polymer emulsion as a binder was added to activated carbon at 30% (in terms of solid content) and stirred to obtain a coating solution of Preparation Example 1.

[Preparation Example 2]
Commercially available powdered coconut shell activated carbon (particle size 40 to 100 μm) is stirred in water at a concentration of 20%. A commercially available acrylic polymer emulsion as a binder was added to activated carbon at 30% (in terms of solid content) and stirred to obtain a coating solution of Preparation Example 2.

[Preparation Example 3]
Commercially available powdered coconut shell activated carbon (particle size 40 to 100 μm) is stirred in water at a concentration of 10%. A commercially available acrylic polymer emulsion as a binder was added to activated carbon at 30% (in terms of solid content) and stirred to obtain a coating solution of Preparation Example 3.

[Water drainage degree]
As a method for measuring the degree of drainage, the measurement was performed in accordance with the Canadian standard drainage test method of JIS P 811-2: 2012. However, as for Comparative Example 4, since it could not be measured, 0.5 g of pulp was collected by absolute drying, and the sieve plate was made of 80 mesh plain weave bronze wire, but JIS P 811-2: 2012 Canadian standard drainage was used. The measurement was performed by a method conforming to the test method.

(Example 1)
After dissociating NBKP at a concentration of 3%, it was prepared using a double disc refiner and a deluxe finer to obtain natural pulp having each physical property value shown in Table 1. Then, using the natural pulp, a sheet having a basis weight of 42 g / m ² is produced by a long net paper machine. Further, a sheet is impregnated with calcium chloride as a hygroscopic agent at 2 g / m ² as a hygroscopic agent under the conditions of a speed of 55 m / min and a nip pressure of 340 kPa with a nip coater, and dried to obtain a base sheet of Example 1. The coating liquid of Preparation Example 1 was uniformly applied to the base material sheet by impregnation coating and dried at 130 ° C. to prepare the total heat exchange element paper of Example 1. The activated carbon content of the total heat exchange element paper of Example 1 was 8.2 g / m ² .

(Example 2)
A base sheet of Example 2 was obtained in the same manner as in Example 1. The coating liquid of Preparation Example 2 was uniformly applied to the base material sheet by impregnation coating and dried at 130 ° C. to prepare the total heat exchange element paper of Example 2. The activated carbon content of the total heat exchange element paper of Example 2 was 2.4 g / m ² .

(Example 3)
The total heat exchange element paper of Example 1 is again uniformly coated with the coating liquid of Preparation Example 1 on the base sheet by impregnation coating, and dried at 130 ° C. to dry the total heat exchange element paper of Example 3. Was produced. The activated carbon content of the total heat exchange element paper of Example 3 was 21.6 g / m ² .

(Examples 4 to 7)
After dissociating NBKP at a concentration of 3%, the total heat of Examples 4 to 7 was prepared in the same manner as in Example 1 except that the NBKP was prepared to each physical property value shown in Table 1 using a double disc refiner and a deluxe finer. Interchangeable element paper was obtained. The activated carbon content of the total heat exchange element papers of Examples 4 to 7 was 8.2 g / m ² .

(Comparative Example 1)
A base sheet of Comparative Example 1 was obtained in the same manner as in Example 1. Let the base material sheet be Comparative Example 1.

(Comparative Example 2)
A base sheet of Comparative Example 2 was obtained in the same manner as in Example 1. The coating liquid of Preparation Example 3 was uniformly applied to the base material sheet by impregnation coating and dried at 130 ° C. to prepare a total heat exchange element paper of Comparative Example 2. The activated carbon content of the total heat exchange element paper of Comparative Example 2 was 1.4 g / m ² .

(Comparative Example 3)
The total heat exchange element paper of Comparative Example 3 was uniformly coated with the coating liquid of Preparation Example 1 on the base sheet by impregnation coating and dried at 130 ° C. to obtain the total heat exchange element paper of Comparative Example 3. Was produced. The activated carbon content of the total heat exchange element paper of Comparative Example 3 was 28.3 g / m ² .

(Comparative Examples 4 to 8)
After dissociating NBKP at a concentration of 3%, the total heat of Comparative Examples 4 to 8 was adjusted in the same manner as in Example 1 except that the NBKP was prepared to each physical property value shown in Table 1 using a double disc refiner and a deluxe finer. Interchangeable element paper was obtained. The activated carbon content of the total heat exchange element papers of Comparative Examples 4 to 8 was 8.2 g / m ² .

The total heat exchange element papers of Examples 1 to 7 and Comparative Examples 1 to 8 were evaluated by the methods shown below. The evaluation results are shown in Table 1.

[Method for evaluating moisture permeability of total heat exchange element paper]
The moisture permeability was measured under the conditions of a temperature of 20 ° C. and a relative humidity of 65% according to the moisture permeability test method specified in JIS Z0208: 1976.

◎: moisture permeability is high at 600g ^{/ m} 2 · 24 hours or more, very good.
○: moisture permeability is 400 g ^{/ m} 2 · 24 hours or more, 600 g ^{/ m} high in less than 2 · 24 hours, good.
△: moisture permeability is 300g ^{/ m} 2 · 24 hours or more, within the allowable range is less than 400g ^{/ m} 2 · 24 hours.
×: moisture permeability is low at less than 300g ^{/ m} 2 · 24 hours, unusable.

[Method for evaluating thermal conductivity of total heat exchange element paper]
The total heat exchange element paper is set vertically in a room having a temperature of 20 ° C., irradiated with an infrared lamp (500 W) from a distance of 30 cm on the surface side thereof, and the surface temperature of the total heat exchange element paper 10 minutes after the start of measurement. And the backside temperature was measured with an infrared radiation thermometer.

〇: The temperature difference between the front surface and the back surface is less than 5 ° C, and the thermal conductivity is good.
Δ: The temperature difference between the front surface and the back surface is 5 to 10 ° C., and the thermal conductivity is within the allowable range.
X: The temperature difference between the front surface and the back surface exceeds 10 ° C., and the thermal conductivity is inferior.

[Strength evaluation method for total heat exchange element paper]
To evaluate the strength, after adjusting the humidity for 24 hours under the conditions of 23 ° C. and 50% relative humidity using total heat exchange element paper, the test width is 15 mm, the test length is 180 mm, and the extension speed is 20 mm / in the flow direction. The tensile strength was measured under the condition of min. The evaluation criteria are as follows.

◯: The tensile strength is strong at 1.5 kN / m or more and is good.
Δ: The tensile strength is 1.0 kN / m or more and less than 1.5 kN / m, which is within the permissible range.
X: The tensile strength is weak at less than 1.0 kN / m and cannot be used.

[Evaluation method of gas shielding property (carbon dioxide leakage amount)]
As an evaluation of the gas shielding property, a total heat exchange element having a length of 200 mm, a width of 200 mm, a height of 250 mm, and a height of 4 mm was produced using the total heat exchange element paper. At this time, 70 g / m ² of bleached kraft paper was used as the spacer. Synthetic air gas containing nitrogen: oxygen at 79:21 was ventilated from the air supply side of the total heat exchange element, and contaminated gas containing carbon dioxide at a constant concentration was ventilated to the exhaust side for ventilation. The carbon dioxide concentration was measured at the outlet on the air supply side, and the amount of carbon dioxide leakage was calculated in% by comparing with the carbon dioxide concentration at the inlet on the exhaust side. The evaluation criteria are as follows.

◯: The amount of carbon dioxide leakage is less than 1%, which is good.
Δ: The amount of carbon dioxide leakage is 1% or more and less than 5%, which is within the permissible range.
×: The amount of carbon dioxide leaked is as large as 5% or more and cannot be used.

[Deodorization test]
The deodorizing efficiency (%) of the total heat exchange element paper cut into 10 cm × 10 cm of Examples and Comparative Examples was measured. Put the total heat exchange element paper in the sampling bag for gas analysis and seal it. Fill the sampling bag with 3 liters of air and add toluene gas to 30 ppm. The concentration (ppm) in the sampling bag was measured with a gas detector tube. The concentration was measured 30 minutes after the addition of toluene gas. From the gas removal rate, it was judged as follows. When the removal rate is 100 to 80%, it is "◎", when it is 79 to 50%, it is "○", when it is 49 to 20%, it is "△", and when it is less than 20%, it is "×".

From the comparison between Examples 1 to 3 and Comparative Examples 1 to 3, the total heat exchange element paper having the active charcoal content of 5 to 30% by mass with respect to the total heat exchange element paper has moisture permeability and thermal conductivity. It can be seen that the total heat exchange element paper is excellent in strength, gas shielding property, and deodorizing property. From the comparison between Examples 1 and 4 to 7 and Comparative Examples 4 to 8, the base material sheet contains activated charcoal and natural pulp, and the length-weighted average fiber length of the natural pulp is 0.7 to 1. It is 7 mm, and in the fiber length histogram of the natural pulp, the ratio of fibers having a maximum frequency peak between 0.5 and 1.5 mm and a fiber length of 1.0 mm or more is 25.0% or more. It can be seen that the total heat exchange element paper is a total heat exchange element paper having excellent strength and gas shielding properties. From Comparative Example 4 and Comparative Example 5, it can be seen that when the proportion of fibers of 1.0 mm or more is less than 25.0%, the strength cannot be obtained. Further, from Comparative Examples 6 to 8, gas shielding property can be obtained when the average fiber length is larger than 1.7 mm and / or when the fiber length of the maximum frequency peak is not in the range of 0.5 to 1.5 mm. It turns out that there is no. Examples 1 to 4 and Example 6 having a second peak in the range of 0.0 to 0.5 mm are described in Examples 5 and 7 having no second peak in the range of 0.0 to 0.5 mm. In comparison, it can be seen that the gas shielding property is excellent.

The total heat exchange element paper of the present invention supplies outside air from which pollutants have been removed, and exchanges humidity (latent heat) as well as temperature (sensible heat) when exhausting dirty air in the room. Used for the total heat exchange element of the vessel.

Claims (3)

In the total heat exchange element paper containing the base sheet, the base sheet contains activated charcoal and natural pulp, and the length-weighted average fiber length of the natural pulp is 0.7 to 1.7 mm. In the fiber length histogram of natural pulp, the ratio of fibers having a maximum frequency peak between 0.5 and 1.5 mm and a fiber length of 1.0 mm or more is 25.0% or more, and the total heat exchange element. A total heat exchange element paper characterized in that the content of activated carbons is 5 to 30% by mass with respect to the paper. The total heat exchange element paper according to claim 1, which has a peak between 0.0 and 0.5 mm in addition to the maximum frequency peak in the fiber length histogram of natural pulp. A total heat exchange element formed by using the total heat exchange element paper according to claim 1 or 2.

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