WO2019026823A1

WO2019026823A1 - Sheet for total heat exchangers, element for total heat exchangers, and total heat exchanger

Info

Publication number: WO2019026823A1
Application number: PCT/JP2018/028397
Authority: WO
Inventors: 浩己山本; 山根　教郎; 絵美相澤
Original assignee: 王子ホールディングス株式会社
Priority date: 2017-07-31
Filing date: 2018-07-30
Publication date: 2019-02-07
Also published as: JP7173012B2; JPWO2019026823A1

Abstract

The purpose of the present invention is to provide: a sheet for total heat exchangers, which has high water vapor permeability and high air permeability, while exhibiting excellent carbon dioxide barrier properties; an element for total heat exchangers, which comprises this sheet for total heat exchangers; and a total heat exchanger which is provided with this element for total heat exchangers. A sheet for total heat exchangers according to the present invention comprises a base material layer and a fiber layer that is arranged on the base material layer; and the fiber layer contains fine cellulose fibers that have fiber widths of 1,000 nm or less, and has a moisture content of 8% by mass or more.

Description

Sheet for total heat exchanger, element for total heat exchanger, and total heat exchanger

The present invention relates to a total heat exchanger sheet, a total heat exchanger element, and a total heat exchanger.

Heretofore, a heat exchange ventilator (heat exchanger) has been proposed as a device capable of ventilating without impairing the effects of cooling and heating, in which heat is exchanged between air supply and exhaust during ventilation. As this heat exchanger, a plurality of partition plates (liners) are stacked via a spacer, and an air supply path for introducing outdoor air into the room and an exhaust path for discharging indoor air to the room are divided. A total heat exchanger is widely adopted which performs heat exchange of latent heat (humidity) simultaneously with sensible heat (temperature).
Patent Document 1 discloses a fine cellulose fiber non-woven fabric layer made of fine cellulose fibers for the purpose of providing a multilayer structure having high air permeability and high moisture permeability and having high suitability as a sheet for a total heat exchanger. A multilayer structure comprising at least one layer is described.

International Publication No. 2014/014099

The present invention is a sheet for a total heat exchanger having high moisture permeability and air permeability and excellent in carbon dioxide barrier properties, a total heat exchanger element having the total heat exchanger sheet, and a total heat exchanger element including the total heat exchanger element It aims at providing a heat exchanger.

The present inventors, in the sheet for total heat exchanger provided with the fiber layer containing the fine cellulose fiber, by setting the water content to a specific content, the air permeability and the moisture permeability are high, carbon dioxide barrier property It has been found that an excellent total heat exchanger sheet can be obtained.
That is, the present invention relates to the following <1> to <18>.
It has a <1> base material layer and the fiber layer provided on this base material layer, This fiber layer contains the fine cellulose fiber of the fiber width of 1,000 nm or less, and moisture content is 8 mass% The above is a sheet for total heat exchangers.
<2> The sheet for total heat exchangers according to <1>, further containing a moisture absorbent.
<3> At least one member selected from metal halides, metal sulfates, metal acetates, amine salts, phosphoric acid compounds, guanidine salts, and metal hydroxides (preferably, metal halide salts) The total heat exchanger sheet according to <2>, more preferably containing at least one selected from the group consisting of an alkali metal halide, an alkaline earth metal halide, still more preferably lithium chloride and calcium chloride.
The sheet | seat for all heat exchangers as described in <2> or <3> whose content of the said moisture absorbent is 100 mass parts or more with respect to 100 mass parts of <4> said fine cellulose fibers.
<5> The fine cellulose fiber is an ionic group (preferably an anionic group, more preferably a phosphoric acid group or a group derived from a phosphoric acid group, a carboxy group or a group derived from a carboxy group, a sulfonic acid group or a sulfonic acid At least one member selected from the group derived from a group, more preferably at least one member selected from a phosphate group or a group derived from a phosphate group, and a carboxy group or a group derived from a carboxy group, still more preferably The total heat exchanger sheet according to any one of <1> to <4>, which has a phosphoric acid group or a group derived from a phosphoric acid group.
<6> The sheet for total heat exchanger according to any one of <1> to <5>, wherein the contact angle of water on the surface on the fiber layer side is 50 ° or more.
When the contact angle of water on one surface of the sheet for all heat exchangers is D1, and the contact angle of water on the other surface is D2, D1 / D2 is 0.25 or more and 4 or less, <1> A sheet for total heat exchangers according to any of <6>.
<8> The sheet for total heat exchanger according to any one of <1> to <7>, wherein the fiber width of the fine cellulose fibers is 30 nm or less.
<9> The sheet for total heat exchanger according to any one of <1> to <8>, wherein the basis weight of the fine cellulose fibers is 0.1 g / m ² or more and 3 g / m ² or less.
<10> A sheet for total heat exchangers according to any one of <1> to <9>, having one base layer and one fiber layer provided on the base layer.
<11> The sheet for total heat exchangers according to any one of <1> to <10>, wherein the water content is 25% by mass or less.
<12> Furthermore, it contains a hygroscopic agent, and the basis weight of the hygroscopic agent is 1 g / m ² or more and 20 g / m ² or less, preferably 3 g / m ² or more and 15 g / m ² or less, more preferably 5 g / m ² or more 12 g / m ² The sheet for total heat exchangers according to any one of <1> to <11>, which is m ² or less.
<13> The sheet for total heat exchanger according to any one of <1> to <12>, wherein the base material layer and the fiber layer contain a hygroscopic agent.
<14> Density is 0.65 g / cm ³ or more and 1.3 g / cm ³ or less (preferably 0.7 g / cm ³ or more and 1.3 g / cm ³ or less, more preferably 0.75 g / cm ³ or more and 1.0 g / cm is ³ or less), <1> to the total heat exchanger sheet according to any one of <13>.
<15> The total heat exchanger sheet according to any one of <1> to <14>, having a thickness of 20 μm to 150 μm (preferably 20 μm to 120 μm, more preferably 30 μm to 100 μm).
<16> basis weight, 10 g / ^{m 2} or more 300 g / ^{m 2} or less (preferably 10 g / ^{m 2} or more 200 g / ^{m 2} or less, more preferably 30 g / ^{m 2} or more 100 g / ^{m 2} or less, more preferably 30 g / a m ² or more 80 g / ^{m 2} or less), <1> the total heat exchanger sheet according to any one of 1 to <15>.
<17> A total heat exchanger element having the total heat exchanger sheet according to any one of <1> to <16>.
The total heat exchanger provided with the element for all the heat exchangers as described in <18><17>.

According to the present invention, a sheet for a total heat exchanger having high moisture permeability and air permeability and excellent in carbon dioxide barrier property, an element for a total heat exchanger having the sheet for the total heat exchanger, and an element for the total heat exchanger A total heat exchanger is provided.

FIG. 1 is a graph showing the relationship between the amount of dropped NaOH and the conductivity of a fiber material having a phosphate group. FIG. 2 is a graph showing the relationship between the amount of dropped NaOH and the electrical conductivity of a fiber material having a carboxy group.

[Seat for all heat exchangers]
The sheet for total heat exchangers of the present invention has a substrate layer and a fiber layer provided on the substrate layer, and the fiber layer contains fine cellulose fibers having a fiber width of 1,000 nm or less, The water content is 8% by mass or more.
The total heat exchanger supplies fresh air and exchanges heat when discharging dirty air in the room. At this time, from the viewpoint of improving the heat exchange efficiency, it is required that the sensible heat (temperature) can be moved to the total heat exchanger sheet and the latent heat (humidity) can also be moved by passing moisture. Be Therefore, moisture permeability and heat conductivity are required.
In addition, high gas barrier properties (mainly, carbon dioxide barrier properties) are also required so that the air supply and the exhaust can not be mixed through the total heat exchanger sheet.

Patent Document 1 describes that by providing a fine cellulose fiber non-woven fabric layer, a multilayer structure having a high air permeability resistance (air permeability) can be obtained, but the influence of the water content of the multilayer structure is described. Has not been considered.
According to the present invention, by setting the water content of the total heat exchanger sheet to a specific range, it is possible to obtain a total heat exchanger sheet having high moisture permeability and air permeability and further excellent in carbon dioxide barrier properties. The detailed mechanism of action by which the above effects can be obtained is unknown, but some are considered as follows.
That is, by providing the fiber layer containing the fine cellulose fiber, high air permeability and carbon dioxide barrier property can be obtained, and further, by making the water content of the total heat exchanger sheet 8% by mass or more, the permeability is improved. It is thought that the humidity has improved. This is because setting the water content of the total heat exchanger sheet to 8% by mass or more makes the total heat exchanger sheet more hydrophilic than when the water content is less than 8% by mass, and the moisture permeability is improved. It is estimated that
Hereinafter, the present invention will be described in more detail.

<Base layer>
The total heat exchanger sheet of the present invention has a substrate layer and a fiber layer provided on the substrate layer.
It does not specifically limit as a base material which comprises a base material layer, The base material selected from a nonwoven fabric, a porous membrane, and a fabric is illustrated preferably.
In the total heat exchanger sheet of the present invention, as described later, it is preferable to form a fiber layer containing fine cellulose on a base material, and to further contain a hygroscopic agent. At this time, the "substrate" means the substrate itself which forms the substrate layer before containing the hygroscopic agent, and the "substrate layer" means the support of the fiber layer in the total heat exchanger sheet. And the entire support layer containing the hygroscopic agent.
Examples of the non-woven fabric include non-woven fabric composed of at least one selected from natural cellulose fiber, nylon fiber, polyester fiber, and polyolefin fiber.
Examples of porous membranes include olefin resins such as polyethylene and polypropylene; polysulfones; fluorine resins such as polytetrafluoroethylene, polyvinyl fluoride and polyvinylidene fluoride; polycarbonates; and nylon resins such as 6-nylon and 6,6-nylon And acrylic resins such as polymethyl methacrylate; polyketones such as poly (1-oxytrimethylene); and porous membranes composed of polyetheretherketone and the like.
Further, examples of the fabric include cellulose fibers including cellulose derivative fibers, nylon fibers, polyurethane fibers, and fabrics (including cross-woven fabrics) formed by mixing yarns thereof.

Among these, the substrate is preferably classified as "paper", which is preferably a non-woven fabric, more preferably a plant pulp fiber such as natural cellulose, from the viewpoint of easy formation of a fiber layer and obtaining a desired water content. Non-woven fabric.
The pulp used as the raw material of the base material may be either softwood pulp or hardwood pulp, and the cooking method and the bleaching method are not particularly limited. It is preferable to use softwood-bleached kraft pulp (NBKP), and it is more preferable to use NBKP as a main raw material, from the viewpoint of the strength of the base material and the carbon dioxide barrier property. In addition to wood pulp, non-wood pulp such as hemp pulp, kenaf and bamboo may be used, and materials other than pulp fiber such as rayon fiber, nylon fiber and other heat-fusion fibers are also used as secondary materials. You may mix | blend.
The content of pulp in the base material is preferably 95% by mass or more, more preferably 98% by mass or more, and 100% by mass from the viewpoint of ease of forming a fiber layer and obtaining a desired water content. It is also good.
As paper, non-coated printing paper such as high quality paper, medium paper etc., information paper such as copying paper, glassine paper processed by high pressure processing (measured by Canadian standard freeness test method (CSF specified in JIS P 8121) For example, the freeness is a degree of beating of about 40 to 80 ml, and semi-glassine paper (the degree of beating of about 100 to 200 ml or so above), which is lower than that of glassine.
Among these, more preferably fine wood paper or semigrass paper, still more preferably semigrass paper.

The air permeability of the substrate is not particularly limited, but it is preferably 5 sec or more, more preferably 10 sec or more, still more preferably 30 sec or more, from the viewpoint of increasing the air permeability of the obtained total heat exchanger sheet. Also, from the viewpoint of economy, it is preferably 1,000 sec or less, more preferably 500 sec or less, and further preferably 200 sec or less. The air permeability is measured by the method described in the examples.

The basis weight of the substrate is not particularly limited, but preferably 5 g / m ² or more, more preferably 10 g / m ² or more, further preferably from the viewpoint of making the basis weight of the obtained total heat exchanger sheet into a desired range. Is 20 g / m ² or more, more preferably 25 g / m ² or more, still more preferably 30 g / m ² or more, still more preferably 35 g / m ² or more, and preferably 200 g / m ² or less, more preferably It is preferably 150 g / m ² or less, more preferably 100 g / m ² or less, and still more preferably 70 g / m ² or less. The basis weight is measured by the method described in the examples.

The thickness of the substrate is not particularly limited, but is preferably 10 μm or more, more preferably 20 μm or more from the viewpoint of obtaining strength as a support, and from the viewpoint of reducing the thickness of the entire heat exchanger sheet. Preferably it is 150 micrometers or less, More preferably, it is 120 micrometers or less, More preferably, it is 100 micrometers or less, More preferably, it is 90 micrometers or less, More preferably, it is 65 micrometers or less. The thickness is measured by the method described in the examples.

The density of the substrate is not particularly limited, but it is preferably 0.3 g / cm ³ or more, more preferably 0.5 g / cm ³ or more, still more preferably from the viewpoint of making the density of the total heat exchanger sheet into a desired range. It is 0.6 g / cm ³ or more, more preferably 0.65 g / cm ³ or more, and preferably 1.3 g in view of easy availability, economy and suppression of the total mass of the entire heat exchanger. / Cm ³ or less, more preferably 1.0 g / cm ³ or less, further preferably 0.85 g / cm ³ or less, still more preferably 0.80 g / cm ³ or less. The density is measured by the method described in the examples.

<Fiber layer>
The total heat exchanger sheet of the present invention has a fiber layer, and the fiber layer contains fine cellulose fibers having a fiber width of 1,000 nm or less. The fiber width of the fine cellulose fiber can be read by, for example, an electron microscope.
The average fiber width of the fine cellulose fiber is preferably 1,000 nm or less, more preferably 100 nm or less, still more preferably 30 nm or less, further preferably from the viewpoint of obtaining a sheet for a total heat exchanger excellent in air permeability and moisture permeability. Is 10 nm or less, more preferably 8 nm or less. The average fiber width of the fine cellulose fiber is preferably 2 nm or more, more preferably 3 nm or more. By setting the average fiber width of the fine cellulose fiber to 2 nm or more, dissolution in water as cellulose molecules is suppressed, and the effect of improving the air permeability and the moisture permeability by the fine cellulose fiber is easily exhibited. The fine cellulose fiber is, for example, monofibrillar cellulose.

The average fiber width of the cellulose fiber is measured as follows using electron microscopy.
First, an aqueous suspension of cellulose fiber having a concentration of 0.05% by mass or more and 0.1% by mass or less is prepared, and the suspension is cast on a hydrophilized carbon film-coated grid to obtain a sample for TEM observation. Do. If wide fibers are included, an SEM image of the surface cast on glass may be observed.
Then, observation with an electron microscope image is performed at a magnification of 1,000 times, 5,000 times, 10,000 times, or 50,000 times depending on the width of the fiber to be observed. However, the sample, observation conditions and magnification are adjusted to satisfy the following conditions.
(1) One straight line X is drawn at an arbitrary position in the observation image, and 20 or more fibers cross the straight line X.
(2) Draw a straight line Y intersecting perpendicularly with the straight line in the same image, and 20 or more fibers cross the straight line Y.
With respect to the observation image satisfying the above conditions, the width of the fiber intersecting with the straight line X and the straight line Y is visually read. In this way, three or more sets of observation images of surface portions not overlapping each other at least are obtained. Then, for each image, the width of the fiber intersecting the straight line X and the straight line Y is read. Thereby, a fiber width of at least 20 × 2 × 3 = 120 is read. And let the average value of the read fiber width be the average fiber width of a cellulose fiber.

The fiber length of the fine cellulose fiber 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, still more preferably 600 μm or less. By setting the fiber length of the fine cellulose fiber within the above range, it is possible to suppress the destruction of the crystal region of the fine cellulose fiber. Moreover, it becomes possible to make the slurry viscosity of a fine cellulose fiber into a suitable range, and formation of a fiber layer becomes easy.
In addition, the fiber length of a fine cellulose fiber can be calculated | required from the image analysis by TEM, SEM, and AFM, for example.

The fine cellulose fiber preferably has a type I crystal structure. Here, the fact that the fine cellulose fiber has a type I crystal structure can be identified in a diffraction profile obtained from a wide angle X-ray diffraction photograph using CuKα (λ = 1.5418 Å) monochromatized with graphite. Specifically, it can be identified from having typical peaks at two positions of 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less.
The proportion of type I crystal structure in the fine cellulose fibers is preferably 30% or more, more preferably 40% or more, and still more preferably 50% or more. This is preferable because a fiber layer having excellent strength can be obtained. With regard to the degree of crystallinity, the X-ray diffraction profile is measured, and the pattern is determined by a conventional method (Seagal et al., Textile Research Journal, 29: 786, 1959).

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

In the present invention, the basis weight (coating amount) of the fine cellulose fiber is preferably 0.1 g / m ² or more, more preferably 0.2 g / m ² or more, from the viewpoint of obtaining high air permeability and moisture permeability. Preferably, it is 0.3 g / m ² or more, and from the viewpoint of making the sheet thickness as a total heat exchanger sheet into a desired range, and an economic point of view, preferably 20 g / m ² or less, more preferably 10 g / M ² or less, more preferably 3 g / m ² or less, still more preferably 1 g / m ² or less.

In the present invention, the fine cellulose fiber preferably has at least one of an ionic group and a nonionic group introduced. In addition, the ionic group and the nonionic group are preferably hydrophilic groups. It is more preferable that the fine cellulose fiber has an ionic group from the viewpoint of improving the dispersibility of the fiber in the dispersion medium and enhancing the disintegration efficiency in the disintegration treatment. The ionic group can contain either or both of an anionic group and a cationic group. In the present invention, it is particularly preferable to have an anionic group as the ionic group.
As the anionic group, there are a phosphate group or a group derived from a phosphate group (also referred to simply as a phosphate group), a carboxy group or a group derived from a carboxy group (also referred to simply as a carboxy group), and a sulfonic acid It is preferably at least one selected from a group derived from a group or a sulfonic acid group (sometimes simply referred to as a sulfonic acid group), and more preferably at least one selected from a phosphoric acid group and a carboxy group Preferably, a phosphate group is particularly preferred.

A phosphoric acid group is a group which functions as a dibasic acid which corresponds to what removed the hydroxy group from phosphoric acid. Groups derived from phosphate groups include salts of phosphate groups, phosphate ester groups and the like. In addition, the group originating in a phosphoric acid group may be contained in the fine cellulose fiber as a group which the phosphoric acid group condensed.
The phosphate group or the group derived from the phosphate group is, for example, a group represented by the following formula (1).

In formula (1), a, b and n are natural numbers (however, a = b × m). alpha ^1, alpha ^2, at least one of · · ·, alpha ⁿ and alpha 'is O ^- a and the remainder is either R or OR. All the alpha ⁿ and alpha 'is O ^- may be a. When n is 2 or more and α 'is R or OR, at least one of each α ⁿ is O 2 ^- and the remainder is R or OR. n is equal to or greater than 2, alpha 'is O ^- when it is may be a respective alpha ⁿ are all R, may be all OR, at least one O ^- remaining in the R or It may be OR. R each independently represents a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched chain Hydrocarbon groups, aromatic hydrocarbon groups, and derivatives thereof.
Examples of the saturated-linear hydrocarbon group include methyl group, ethyl group, n-propyl group, and n-butyl group, but are not particularly limited. Examples of the saturated-branched hydrocarbon group include i-propyl group and t-butyl group, but are not particularly limited. The saturated-cyclic hydrocarbon group may, for example, be a cyclopentyl group or a cyclohexyl group, but is not particularly limited. Examples of the unsaturated-linear hydrocarbon group include, but are not particularly limited to, a vinyl group, an allyl group and the like. Examples of unsaturated-branched hydrocarbon groups include i-propenyl group and 3-butenyl group, but are not particularly limited. As an aromatic hydrocarbon group, although a phenyl group or a naphthalene group etc. are mentioned, it is not limited in particular.
In addition, as the derivative in R, at least one of functional groups such as a carboxy group, a hydroxy group, or an amino group is added or substituted to the main chain or side chain of the various hydrocarbon groups. Although a group is mentioned, it is not limited in particular. The number of carbon atoms constituting the main chain of R is not particularly limited, but is preferably 20 or less, and more preferably 10 or less. By setting the number of carbon atoms constituting the main chain of R to 20 or less, it is possible to prevent the molecule of the phosphorus oxo acid group containing R from becoming too large and maintain good permeability to the fiber material, It can contribute to the improvement of the yield of fine cellulose fiber.
β ^{b +} is a b-valent cation consisting of an organic substance or an inorganic substance. Examples of organic b-valent cations include aliphatic ammonium or aromatic ammonium, and examples of inorganic b-valent cations include ions of alkali metals such as sodium, potassium or lithium, calcium, and the like. Or a cation of a divalent metal such as magnesium, or a hydrogen ion, but is not particularly limited. These can also be applied combining 1 type or 2 or more types. The b-valent cation composed of an organic substance or an inorganic substance is preferably an ion of sodium or potassium which is not easily yellowed when the fiber material containing β is heated and which is industrially easy to use, but is not particularly limited.

The amount of ionic group introduced into the fine cellulose fiber is preferably 0.10 mmol / g or more, more preferably 0.20 mmol / g or more, still more preferably 0.50 mmol / g or more, per 1 g (mass) of the fine cellulose fiber. Still more preferably, it is 1.00 mmol / g or more. The amount of ionic group introduced into the fine cellulose fiber is preferably 3.65 mmol / g or less, more preferably 3.50 mmol / g or less, still more preferably 3.00 mmol / g, per 1 g (mass) of the fine cellulose fiber. It is below. By setting the introduction amount of the ionic group within the above range, it is possible to facilitate the miniaturization of the fiber raw material, and it is possible to enhance the stability of the fine cellulose fiber. In addition, by setting the introduction amount of the ionic group within the above range, disentanglement becomes easier.
The introduction amount of the ionic group to the fine cellulose fiber can be measured, for example, by the conductivity titration method. In the measurement by the conductivity titration method, the introduced amount is measured by determining the change in conductivity while adding an alkali such as an aqueous solution of sodium hydroxide to the obtained slurry containing fine cellulose fibers.

FIG. 1 is a graph showing the relationship between the amount of dropped NaOH and the electrical conductivity for fine cellulose fibers having a phosphate group.
The introduced amount of phosphate group to cellulose fiber is measured as follows.
First, a slurry containing cellulose fibers is treated with an ion exchange resin. In addition, before the process by an ion exchange resin, you may implement the disintegration processing similar to the below-mentioned disintegration processing process with respect to a measuring object as needed. Then, while the aqueous sodium hydroxide solution is added, the change in electrical conductivity is observed to obtain a titration curve as shown in FIG.
As shown in FIG. 1, at the beginning, the electrical conductivity rapidly decreases (hereinafter, referred to as “first region”). Thereafter, the conductivity starts to rise slightly (hereinafter referred to as "the second region"). Thereafter, the conductivity increment is increased (hereinafter referred to as "third region"). The boundary point between the second area and the third area is defined as a point at which the second derivative value of the conductivity, that is, the change amount of the increment (inclination) of the conductivity is maximum. Thus, three regions appear in the titration curve. Among them, the amount of alkali required in the first region is equal to the amount of strongly acidic groups in the slurry used for titration, and the amount of alkali required in the second region is the amount of weakly acidic groups in the slurry used for titration Become equal. When the phosphoric acid group causes condensation, the weakly acidic group is apparently lost, and the amount of alkali required for the second region is smaller than the amount of alkali required for the first region. On the other hand, the amount of strongly acidic groups is the same as the amount of phosphorus atoms regardless of the presence or absence of condensation. Therefore, simply referring to the amount of introduction of phosphate group (or the amount of phosphate group) or the amount of introduction of substituents (or the amount of substituent group) means the amount of strongly acidic group. Therefore, the value obtained by dividing the amount of alkali (mmol) required in the first region of the titration curve obtained above by the solid content (g) in the slurry to be titrated is the amount of phosphate introduced (mmol / g).

FIG. 2 is a graph showing the relationship between the amount of dropped NaOH and the electrical conductivity for fine cellulose fibers having a carboxy group.
The amount of carboxy group introduced into the fine cellulose fiber is measured as follows.
First, a change in electric conductivity is observed while adding an aqueous solution of sodium hydroxide to a slurry containing fine cellulose fibers to be measured, and a titration curve as shown in FIG. 2 is obtained. In addition, you may implement the disintegration processing similar to the below-mentioned disintegration processing process with respect to a measuring object as needed. The titration curve, as shown in FIG. 2, shows that after the conductivity decreases, the first region until the conductivity increment (slope) becomes almost constant, and then the conductivity increment (slope) increases. It is divided into the second area. The boundary point between the first region and the second region is defined as a point at which the second derivative value of the conductivity, that is, the amount of change in the conductivity increment (slope) becomes maximum. And the value obtained by dividing the amount of alkali (mmol) required in the first region of the titration curve by the solid content (g) in the fine cellulose fiber-containing slurry to be titrated is the amount of introduction of carboxy group (mmol) / G).

In addition, since "g" of a denominator is a mass of the fine cellulose fiber of an acid type, as for the said phosphoric acid group introduction amount (mmol / g), "the amount of phosphoric acid groups which an acidic cellulose fiber has" (following, The amount of phosphate group (referred to as acid type) is shown. Here, when the proton of the phosphate group is substituted by an arbitrary cation C so as to be a charge equivalent, “g” of the denominator is the mass of the cellulose fiber when the cation C is a counter ion By conversion, “the amount of phosphoric acid groups possessed by the cellulose fiber in which the cation C is a counter ion” (hereinafter, the amount of phosphoric acid groups (C type)) can be determined.
That is, it calculates with the following formula.
Amount of phosphoric acid group (C type) = amount of phosphoric acid group (acid type) / {1 + (W-1) x A / 1000}
here,
A [mmol / g]: total amount of anion derived from the phosphate group of the cellulose fiber (value obtained by adding the amount of strongly acidic group and the amount of weakly acidic group of the phosphate group)
W: Formula weight per monovalent C cation (for example, 23 for Na, 9 for Al)
It is.

In addition, since "g" of the denominator is the mass of acid type cellulose fiber, the carboxy group introduction amount (mmol / g) means that "carboxy group amount of acid type cellulose fiber" (hereinafter, carboxy group amount (Referred to as acid type)). Here, when the proton of the carboxy group is substituted by an arbitrary cation C so as to be a charge equivalent, “g” of the denominator is converted to the mass of the cellulose fiber when the cation C is a counter ion By doing this, “the amount of carboxy groups possessed by the cellulose fiber in which the cation C is a counter ion” (hereinafter, the amount of carboxy groups (C type)) can be determined.
That is, it calculates with the following formula.
Carboxyl group weight (C type) = Carboxyl group weight (acid type) / {1+ (W-1) × (Carboxyl group weight (acid type)) / 1000}
here,
W: Formula weight per monovalent C cation (for example, 23 for Na, 9 for Al)
It is.

In order to obtain the fine cellulose fiber which introduced the above-mentioned ionic group, the ionic group introduction process which introduces an ionic group to a fiber raw material, the washing process, the alkali treatment process (neutralization process), and the fibrillation treatment process In this order, it is preferable to have an acid treatment step instead of or in addition to the washing step. A phosphoric acid group introduction process and a carboxy group introduction process are illustrated as an ionicity group introduction process. Each of the steps will be described below.
(Ionic group introduction process)
[Phosphoric acid group introduction process]
The process (phosphate group introduction process) of introducing a phosphate group to cellulose fiber will be described below.
The phosphoric acid group introducing step contains at least one compound (hereinafter also referred to as "compound A") selected from compounds which can react with the hydroxyl group of the fiber raw material containing cellulose and can introduce a phosphoric acid group. It is the process of acting on the fiber material.
In the phosphate group introducing step, the reaction between the fiber material containing cellulose and the compound A may be carried out in the presence of at least one selected from urea and derivatives thereof (hereinafter also referred to as “compound B”). On the other hand, the reaction between the fiber material containing cellulose and the compound A may be carried out in the absence of the compound B.

From the viewpoint of high efficiency of introduction of the phosphate group, easy improvement of the fibrillation efficiency in the fibrillation step described later, low cost, and easy industrial application, phosphoric acid and phosphoric acid are used as the compound A. Sodium salt of phosphoric acid, potassium salt of phosphoric acid, or ammonium salt of phosphoric acid is preferable, and phosphoric acid, sodium dihydrogen phosphate, or disodium hydrogen phosphate, ammonium dihydrogen phosphate is more preferable.
The amount of compound A added to the fiber raw material is not particularly limited, but when the amount of compound A added is converted to phosphorus atomic weight, the amount of phosphorus atom added to 100 parts by mass of fiber raw material (absolute dry mass) is preferably 0. .5 parts by mass or more, more preferably 1 part by mass or more, further preferably 2 parts by mass or more, and preferably 100 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 30 parts by mass or less . By making the addition amount of the phosphorus atom with respect to a fiber raw material into the said range, the yield of a fine cellulose fiber can be improved more. On the other hand, by setting the addition amount of phosphorus atoms to the fiber raw material to the upper limit value or less, it is possible to balance the effect of improving the yield and the cost.

The compound B used in this embodiment is at least one selected from urea and derivatives thereof as described above. As compound B, urea, biuret, 1-phenylurea, 1-benzylurea, 1-methylurea, 1-ethylurea and the like can be mentioned.
From the viewpoint of improving the uniformity of the reaction, the compound B is preferably used as an aqueous solution. Further, from the viewpoint of further improving the homogeneity of the reaction, it is preferable to use an aqueous solution in which both the compound A and the compound B are dissolved.
The addition amount of the compound B with respect to 100 parts by mass of the fiber raw material (absolute dry mass) is not particularly limited, but is preferably 1 part by mass or more, more preferably 10 parts by mass or more, still more preferably 100 parts by mass or more Preferably it is 500 mass parts or less, More preferably, it is 400 mass parts or less, More preferably, it is 350 mass parts or less.

In the reaction of the fiber material containing cellulose and the compound A, in addition to the compound B, an amide or an amine may be included in the reaction system. Examples of the amides include formamide, dimethylformamide, acetamide, dimethylacetamide and the like. Examples of amines include methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, hexamethylenediamine and the like. Among these, triethylamine is known to work as a good reaction catalyst.

In the phosphoric acid group introducing step, it is preferable to heat treat the fiber material after adding or mixing the compound A and the like to the fiber material. As the heat treatment temperature, it is preferable to select a temperature at which the phosphoric acid group can be efficiently introduced while suppressing the thermal decomposition or hydrolysis reaction of the fiber. The heat treatment temperature is preferably 50 ° C. or more, more preferably 100 ° C. or more, still more preferably 130 ° C. or more, and preferably 300 ° C. or less, more preferably 250 ° C. or less, still more preferably 200 ° C. or less .
Moreover, the heat processing can utilize the apparatus which has various thermal media, and a stirring dryer, a rotary dryer, a disk dryer, a roll type heating apparatus, a plate type heating apparatus, a fluidized bed drying apparatus, a flash drying apparatus , A vacuum drying apparatus, an infrared heating apparatus, a far infrared heating apparatus, and a microwave heating apparatus are exemplified.
In the heat treatment, for example, a method of impregnating a thin sheet of fiber raw material with the compound A by a method such as impregnation, and heating, or a method of heating and drying while kneading or stirring the fiber raw material and compound A with a kneader etc. can do. Thereby, it becomes possible to suppress the concentration nonuniformity of the compound A in a fiber raw material, and to introduce | transduce a phosphate group more uniformly to the cellulose fiber surface contained in a fiber raw material. This is because when water molecules move to the surface of the fiber material with drying, the compound A to be dissolved is attracted to the water molecules by surface tension and moves to the surface of the fiber material (that is, concentration unevenness of the compound A occurs) It is thought that it is because it can be suppressed.

In addition, as a heating device used for the heat treatment, the water contained in the slurry and the water generated by the dehydration condensation (phosphorylation of esterification) of the compound A and the hydroxyl group contained in the cellulose etc. It is preferable that it is an apparatus which can be discharged outside. As such a heating device, for example, an air-blowing oven may be mentioned. In addition to being able to suppress the hydrolysis reaction of the phosphate ester bond which is the reverse reaction of phosphoric acid esterification by always draining the water in the device system, it is also possible to suppress the acid hydrolysis of the sugar chain in the fiber. it can. For this reason, it is possible to obtain fine fibers with a desired axial ratio.

The heat treatment time is preferably 1 second or more, more preferably 10 seconds or more, and preferably 300 minutes or less, more preferably 1,000 seconds or less after substantially removing moisture from the fiber raw material. More preferably, it is 800 seconds or less. By making heating temperature and heating time into a suitable range, the introduction amount of a phosphoric acid group can be carried out in a preferable range.

The phosphate group introduction step may be performed at least once, but may be repeated twice or more. By performing the phosphate group introduction step twice or more, many phosphate groups can be introduced into the fiber material. In the present invention, as an example of a preferable embodiment, the case of performing the phosphate group introducing step twice is mentioned.

The amount of phosphoric acid group introduced per 1 g (mass) of the fine cellulose fiber is preferably 0.10 mmol / g or more, more preferably 0.20 mmol / g or more, still more preferably 0.50 mmol / g or more, still more preferably It is 1.00 mmol / g or more. Moreover, the introduction amount of the phosphate group per 1 g (mass) of the fine cellulose fiber is preferably 5.20 mmol / g or less, more preferably 3.65 mmol / g or less, and further preferably 3.00 mmol / g or less. It is preferable to introduce a phosphate group into the fiber raw material so that the amount of phosphate group introduced into the fine cellulose fiber falls within the above range. By making the introduction amount of the phosphoric acid group within the above range, it is possible to facilitate the miniaturization of the fiber raw material and to enhance the stability of the fine cellulose fiber.

[Carboxyl group introduction step]
The process (carboxyl group introduction process) which introduce | transduces a carboxy group into a cellulose fiber is demonstrated below.
The carboxy group introducing step has a fiber material containing cellulose, a compound having an oxidation treatment such as oxidation by ozone oxidation, Fenton method, TEMPO oxidation treatment, a group derived from a carboxylic acid or a derivative thereof, or a group derived from a carboxylic acid. It is carried out by treatment with an acid anhydride of the compound or a derivative thereof.
The compound having a group derived from carboxylic acid is not particularly limited, but dicarboxylic acids such as maleic acid, succinic acid, phthalic acid, fumaric acid, glutaric acid, adipic acid and itaconic acid, tricarboxylic acids such as citric acid and aconitic acid Acid compounds are mentioned. The derivative of the compound having a group derived from a carboxylic acid is not particularly limited, but examples thereof include an imidized acid anhydride of a compound having a carboxy group and a derivative of an acid anhydride of a compound having a carboxy group. Although it does not specifically limit as an imide compound of the acid anhydride of the compound which has a carboxy group, The imidate of dicarboxylic acid compounds, such as maleimide, a succinimide, and a phthalimide, is mentioned.

When TEMPO oxidation treatment is carried out in the carboxy group introduction step, it is preferable to carry out under the conditions of pH 6 or more and 8 or less. Such treatment is also referred to as neutral TEMPO oxidation treatment. Neutral TEMPO oxidation treatment is carried out, for example, with sodium phosphate buffer (pH = 6.8), pulp as a fiber raw material, TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) as a catalyst, etc. It can be carried out by adding a nitroxy radical, sodium hypochlorite as a sacrificial reagent. Further, by coexisting sodium chlorite, aldehyde generated in the process of oxidation can be efficiently oxidized to a carboxy group.

When a carboxy group is introduced by TEMPO oxidation, the amount of carboxy group introduced per 1 g (mass) of the fine cellulose fiber is preferably 0.10 mmol / g or more, more preferably 0.20 mmol / g or more, still more preferably 0. It is 50 mmol / g or more, more preferably 0.90 mmol / g or more. Moreover, Preferably it is 2.50 mmol / g or less, More preferably, it is 2.20 mmol / g or less, More preferably, it is 2.00 mmol / g or less. In addition, when the substituent is a carboxymethyl group, the introduction amount per 1 g (mass) of the fine cellulose fiber may be 5.8 mmol / g or less.
It is preferable to introduce a carboxy group into the fiber material so that the amount of carboxy group introduced into the fine cellulose fiber is in the above range. By making the introduction amount of the carboxy group within the above range, it is possible to facilitate the miniaturization of the fiber raw material and to enhance the stability of the fine cellulose fiber.

(Washing process)
In order to reduce the amount of alkaline solution used in the alkaline treatment step, the ionic group-introduced fiber may be washed with water or an organic solvent after the ionic group introduction step and before the alkaline treatment step. After the alkali treatment step and before the defibration treatment step, from the viewpoint of improving the handleability, the alkali group introduced fibers such as phosphate group introduced fibers which have been subjected to alkali treatment are washed with water or an organic solvent Is preferred.
In the washing step, it is preferable to repeat the filtration operation after dispersing the ionic group-introduced fiber in water or an organic solvent, and control the progress of the washing step by setting the electric conductivity of the filtrate to a desired range. Can. The washing step is carried out so that the conductivity of the filtrate is preferably 10,000 μS / cm or less, more preferably 1,000 μS / cm or less, still more preferably 300 μS / cm or less, still more preferably 150 μS / cm Is preferred.

(Alkali treatment process (neutralization process))
When producing a fine cellulose fiber, an alkali treatment is performed on the fiber raw material to neutralize the ionic group between the ionic group introduction step and the defibration treatment step described later. It may have a sum process). Although it does not specifically limit as the method of alkali treatment, For example, the method of immersing an ionic group introduce | transducing fiber in an alkali solution is mentioned.
The alkali compound contained in the alkali solution is not particularly limited, and may be an inorganic alkali compound or an organic alkali compound. In the present invention, it is preferable to use sodium hydroxide or potassium hydroxide as an alkali compound because of its high versatility. Also, the solvent contained in the alkaline solution may be either water or an organic solvent. The solvent contained in the alkaline solution is preferably a polar solvent containing water or a polar organic solvent exemplified by alcohols, and more preferably an aqueous solvent containing at least water. As the alkali solution, a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution is preferable because of high versatility.

The temperature of the alkali solution in the alkali treatment step is not particularly limited, but is preferably 5 ° C. or more, more preferably 10 ° C. or more, and preferably 80 ° C. or less, more preferably 60 ° C. or less. The immersion time of the ionic group-introduced fiber into the alkali solution in the alkali treatment step is not particularly limited, but is preferably 5 minutes or more, more preferably 10 minutes or more, and preferably 30 minutes or less, more preferably 20 It is less than a minute.
The use amount of the alkali solution in the alkali treatment is not particularly limited, but is preferably 100 parts by mass or more, more preferably 1,000 parts by mass or more, with respect to 100 parts by mass of the dry mass of the ionic group-introduced fiber. And preferably 100,000 parts by mass or less, more preferably 10,000 parts by mass or less.

In the alkali treatment, for example, when a phosphate group is introduced as an ionic group, an alkaline solution is gradually added to the dispersion in which the ionic group-introduced fiber is dispersed, and the pH in the system is preferably 10 or more. It is preferable to add an alkaline solution so that it is preferably 11 or more, more preferably 12 or more, and preferably 14 or less, more preferably 13.5 or less, and further preferably 13 or less.
When a carboxy group is introduced as an ionic group, the pH in the system is preferably 7 or more, more preferably 8 or more, still more preferably 9 or more, still more preferably 10 or more, and preferably 14 or less It is preferable to add an alkali solution so as to be more preferably 13.5 or less, further preferably 13 or less.
By setting the addition amount of the alkaline solution in the above range, the defibration treatment can be more easily performed, and the fine cellulose fiber with a small fiber width can be easily obtained.

(Acid treatment process)
In the production of the fine cellulose fiber, an acid treatment may be performed on the ionic group-introduced fiber raw material between the ionic group introduction step and the defibration treatment step described later. As an example of the manufacturing method of a fine cellulose fiber, the aspect which performs an ionic group introduction process, an acid treatment process, an alkali treatment process, and a disintegration treatment process in this order is mentioned.
Although it does not specifically limit as the method of an acid treatment, The method of immersing a fiber raw material in the acidic liquid containing an acid is mentioned. The concentration of the acidic solution to be used is not particularly limited, but is preferably 10% by mass or less, more preferably 5% by mass or less. The pH of the acidic solution to be used is not particularly limited, but is preferably 0 or more, more preferably 1 or more, and preferably 4 or less, more preferably 3 or less.

Examples of the acid contained in the acidic solution include inorganic acids, sulfonic acids and carboxylic acids.
Examples of inorganic acids include sulfuric acid, nitric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, hypochlorous acid, chlorous acid, chloric acid, perchloric acid, phosphoric acid, boric acid and the like.
Examples of the sulfonic acid include methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid and the like.
Examples of carboxylic acids include formic acid, acetic acid, citric acid, gluconic acid, lactic acid, oxalic acid and tartaric acid.
Among these, it is particularly preferable to use hydrochloric acid or sulfuric acid.

The temperature of the acid solution in the acid treatment is not particularly limited, but is preferably 5 ° C. or more, more preferably 20 ° C. or more, and preferably 100 ° C. or less, more preferably 90 ° C. or less.
The immersion time to the acid solution in the acid treatment is not particularly limited, but is preferably 5 minutes or more, more preferably 10 minutes or more, and preferably 120 minutes or less, more preferably 60 minutes or less.
The use amount of the acid solution in the acid treatment is not particularly limited, but preferably 100 parts by mass or more, more preferably 1,000 parts by mass or more with respect to 100 parts by mass of the absolute dry mass (absolute dry mass) of the fiber material. And preferably 100,000 parts by mass or less, more preferably 10,000 parts by mass or less.

(Disintegration process)
The ionizable group-introduced fiber is subjected to a defibration treatment in a defibration treatment step to obtain a fine cellulose fiber.
In the defibration treatment step, a defibration treatment apparatus can be used. The fibrillation treatment apparatus is not particularly limited, but a high-speed fibrillation machine, a grinder (stone mill type crusher), a high pressure homogenizer or an ultrahigh pressure homogenizer, a high pressure collision type crusher, a ball mill, a bead mill, a bead mill, a disc type refiner, a conical refiner, biaxial kneading Machine, vibration mill, homomixer under high speed rotation, ultrasonic dispersion machine, beater, etc. can be used, and solid content concentration of the fine cellulose fiber at the time of disentanglement processing can be set suitably. It is more preferable to use a high-speed fibrillation machine, a high pressure homogenizer, or an ultrahigh pressure homogenizer which is less affected by the grinding media and less likely to contaminate among the above-mentioned fibrillation treatment apparatuses.

In the defibration treatment step, it is preferable to dilute the ionic group-introduced fiber with a dispersion medium to form a slurry. As the dispersion medium, one or more selected from water and an organic solvent such as a polar organic solvent can be used.
The polar organic solvent is not particularly limited, but alcohols, polyhydric alcohols, ketones, ethers, esters, non-proton polar solvents and the like are preferably exemplified.
Examples of alcohols include methanol, ethanol, isopropanol, n-butanol, isobutyl alcohol and the like. Examples of polyhydric alcohols include ethylene glycol, propylene glycol and glycerin. Examples of ketones include acetone, methyl ethyl ketone (MEK) and the like. The ethers include diethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono n-butyl ether, propylene glycol monomethyl ether and the like. Examples of esters include ethyl acetate and butyl acetate. Examples of the aprotic polar solvent include dimethylsulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl-2-pyrrolidinone (NMP) and the like.
Further, in the slurry obtained by dispersing the ionic group-introduced fiber in the dispersion medium, solid content other than the ionic group-introduced fiber such as urea having hydrogen bonding property may be contained, for example.

(Coarse cellulose fiber)
As described above, the step of obtaining the fine cellulose fiber includes the step of refining the fiber raw material (coarse cellulose fiber). At this time, most of the coarse cellulose fibers are refined, but some of them may remain unrefined. In such a case, coarse cellulose fibers will be contained in the fiber layer.
In the present invention, the coarse cellulose fiber contained in the cellulose fiber-containing composition is prepared by adjusting the cellulose dispersion to a solid content concentration of 0.2% by mass, and a cooling high-speed centrifuge (Kokusan Co., Ltd., H-2000B) It is a cellulose fiber that settles when it is centrifuged at 12,000 G for 10 minutes using
Less sedimented components means that the yield of supernatant after centrifugation is high. It is preferable that the supernatant yield after this centrifugation is 80 mass% or more with respect to the total mass of a cellulose fiber. The supernatant yield after centrifugation is more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 99% by mass or more. In addition, the supernatant yield after centrifugation of said fine cellulose fiber dispersion liquid can be measured by the following method in this specification.
The supernatant yield after centrifuging the fine cellulose fiber dispersion was measured by the method described below. The supernatant yield after centrifugation is an index of the yield of fine cellulose fibers, and the higher the supernatant yield, the higher the yield of fine cellulose fibers.
The fine cellulose fiber dispersion is adjusted to a solid concentration of 0.2% by mass, and centrifuged at 12,000 G for 10 minutes using a cooling high-speed centrifuge (Kokusan Co., Ltd., H-2000B). The obtained supernatant was collected, and the solid concentration of the supernatant was measured. The yield of fine cellulose fibers is determined based on the following equation.
Fine cellulose fiber yield (%) = supernatant solid concentration (%) / 0.2 x 100

(Method of forming fiber layer)
In the present invention, the method of providing the fiber layer on the substrate is not particularly limited, and may be formed by a paper making method, or after fine cellulose fibers are applied on the substrate by coating, spraying or the like, and then dried. You may form a fiber layer.
The concentration of the fine cellulose fiber dispersion used to apply papermaking or fine cellulose fibers is not particularly limited, but from the viewpoint of suppressing an increase in viscosity, it is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably It is 3% by mass or less, more preferably 1.5% by mass or less, still more preferably 1% by mass or less, preferably 0.05% by mass or more from the viewpoint of efficiently applying fine cellulose fibers to a substrate More preferably, it is 0.1 mass% or more, More preferably, it is 0.3 mass% or more, More preferably, it is 0.5 mass% or more.
The concentration of the fine cellulose fiber dispersion and the amount applied to the substrate may be appropriately adjusted so that the basis weight (coating amount) of the fine cellulose fibers after drying falls within the above-described desired range.

<Water content>
The sheet for total heat exchangers of the present invention has a water content of 8% by mass or more. If the water content is less than 8% by mass, it is difficult to obtain high moisture permeability.
The moisture content can be adjusted by highly controlling the manufacturing process of the total heat exchanger sheet. According to the present inventors, for example, it is presumed that the type, blending amount, addition method, and the like of the fine cellulose fiber and the hygroscopic agent that constitute the sheet affect the water content.
The water content of the total heat exchanger sheet is preferably 9% by mass or more, more preferably 10% by mass or more, still more preferably 12% by mass or more, still more preferably 15% by mass or more from the viewpoint of obtaining high moisture permeability. It is. In addition, from the viewpoint of preventing condensation and enhancing the strength of the total heat exchange sheet, the water content of the total heat exchanger sheet is preferably 30% by mass or less, more preferably 25% by mass or less, still more preferably It is 20 mass% or less.
The moisture content (moisture content) of the total heat exchanger sheet is measured by the method described in the examples.

(Hygroscopic agent)
The total heat exchanger sheet of the present invention preferably contains a hygroscopic agent to obtain a desired moisture content. The hygroscopic agent may be contained in either the base layer or the fiber layer, or may be contained in both the base layer and the fiber layer, but the ease of the production method and the fiber layer side It is preferable that both the base material layer and the fiber layer contain from the viewpoint of increasing the contact angle at the surface of the above. As described later, the contact angle is preferably high.
The hygroscopic agent is not particularly limited as long as it is a conventionally known hygroscopic agent, and may be appropriately selected and used. Specifically, at least one selected from metal halides, metal lactates, metal sulfates, metal acetates, amine salts, phosphoric acid compounds, guanidine salts, and metal hydroxides is preferable.
Examples of metal halides include lithium chloride, sodium chloride, calcium chloride, magnesium chloride, aluminum chloride, zinc chloride and the like, and metal lactates include sodium lactate and the like, and metal sulfates include sodium sulfate Calcium sulfate, magnesium sulfate, zinc sulfate and the like are exemplified, and as metal acetate, potassium acetate and the like are exemplified.
Further, examples of the amine salt include dimethylamine hydrochloride and the like, examples of the phosphoric acid compound include orthophosphoric acid and the like, and examples of the guanidine salt include guanidine hydrochloride, guanidine phosphate, and guanidine sulfamate. Furthermore, potassium hydroxide, sodium hydroxide, magnesium hydroxide etc. are illustrated as a metal hydroxide.
Furthermore, a water-soluble polymer which is a hygroscopic polymer, or a hydrophilic polymer having a hydrogel forming ability may be used as a hygroscopic agent.
Among them, the hygroscopic agent is preferably a metal salt, more preferably a metal halide salt, more preferably an alkali metal halide, from the viewpoints of excellent hygroscopicity and handleability and increasing the contact angle to water. It is more preferably an alkaline earth metal halide, and even more preferably at least one selected from the group consisting of lithium chloride and calcium chloride.
The present inventors initially predicted that the hydrophilicity of the total heat exchanger sheet is enhanced by containing the hygroscopic agent in the total heat exchanger sheet, and as a result, the contact angle of water is lowered. However, when the hygroscopic agent is a metal salt and the fine cellulose fiber has an ionic group, in particular an anionic group, the contact angle of water on the surface on the fiber layer side is increased as an unexpected effect. Although the detailed reason is unknown, the cross-linked structure is formed in a pseudo manner by the anionic group contained in the fine cellulose fiber and the metal atom of the hygroscopic agent, and as a result, the surface becomes hydrophobic and the water It is believed that the contact angle increases.
From the above viewpoint, an embodiment is particularly preferable in which the fine cellulose fiber has a carboxy group or a phosphoric acid group as an anionic group, preferably a phosphoric acid group, and the hygroscopic agent contains lithium chloride or calcium chloride.

The content of the hygroscopic agent in the total heat exchanger sheet is preferably 100 parts by mass or more, more preferably 100 parts by mass of the fine cellulose fibers from the viewpoint of making the water content of the total heat exchanger sheet into a desired range. Is 300 parts by mass or more, more preferably 500 parts by mass or more, still more preferably 600 parts by mass and preferably 10,000 parts by mass or less, more preferably 5,000 parts by mass or less, still more preferably 2 , 500 parts by mass or less.
The basis weight (coating amount) of the hygroscopic agent in the total heat exchanger sheet is preferably 1 g / m ² or more, more preferably 3 g / m ² or more from the viewpoint of making the water content of the total heat exchanger sheet into a desired range. , More preferably 5 g / m ² or more, and preferably 20 g / m ² or less, more preferably 15 g / m ² or less, still more preferably 12 g / m ² or less.

The method for allowing the sheet for total heat exchanger to contain a hygroscopic agent is not particularly limited, but from the viewpoint of increasing the contact angle of water on the surface of the fiber layer side, it is preferable to contain a hygroscopic agent after forming the fiber layer, After forming the layer, a method of spraying and applying an aqueous solution in which a hygroscopic agent is dissolved, and a method of immersing in an aqueous solution in which a hygroscopic agent is dissolved are preferably exemplified.
According to this method, the contact angle of water on the surface on the fiber layer side can be further improved as compared with the method of forming the fiber layer after applying the hygroscopic agent to the base material layer in advance. Moreover, compared with the method of adding a hygroscopic agent to a fine cellulose fiber dispersion liquid, and providing it to a base material, aggregation of a fine cellulose fiber in a dispersion liquid can be suppressed more effectively.

<Sheet for total heat exchanger>
Below, the preferable aspect of the sheet | seat for total heat exchangers of this invention is demonstrated.
The total heat exchanger sheet of the present invention is not particularly limited as long as it has at least one base layer and at least one fiber layer, and has a fiber layer on both sides of the base layer. It may be a three-layer structure of a material layer / fiber layer, or may be a two-layer structure of a fiber layer / substrate layer having a fiber layer on one side, and is not particularly limited.
Among these, a two-layer structure of a fiber layer / substrate layer is preferable from the viewpoint of easy production, sufficient moisture permeability and air permeability, and carbon dioxide barrier property with a single fiber layer.

The density of the total heat exchanger sheet of the present invention is preferably 0.65 g / cm ³ or more, more preferably 0.7 g / cm ³ or more, still more preferably 0.75 g / cm ³ from the viewpoint of improving the heat conductivity. It is above. The upper limit of the density is not particularly limited, but is preferably 1.3 g / cm ³ or less, more preferably 1.0 g / cm ³ or less, from the viewpoint of suppressing the mass of the entire heat exchanger.
The density of the total heat exchanger sheet is measured by the method described in the examples.

The thickness of the sheet for total heat exchanger of the present invention is preferably thin from the viewpoint that many sheets can be arranged in the total heat exchanger, and specifically, preferably 150 μm or less, more preferably 120 μm or less, and further preferably Preferably it is 100 micrometers or less.
Moreover, from a viewpoint of maintaining the intensity | strength required as a sheet | seat for all heat exchangers, Preferably it is 20 micrometers or more, More preferably, it is 30 micrometers or more.

The basis weight of the total heat exchanger sheet according to the present invention, from the viewpoint of obtaining a desired density and thickness, preferably 10 g / ^{m 2} or more, more preferably 30 g / ^{m 2} or more, and preferably 300 g / ^{m 2} The following content is more preferably 200 g / m ² or less, still more preferably 100 g / m ² or less, still more preferably 80 g / m ² or less.

When the sheet for total heat exchangers of the present invention has a fiber layer on at least one surface of the outer surface, the contact angle of water on the surface on the fiber layer side is preferably 50 ° or more. When the contact angle of water is 50 ° or more, the spread of the adhesive is suppressed when the spacer and the liner are bonded and assembled as an element for a total heat exchanger, and the effective area of the sheet (liner) for a total heat exchanger The reduction is suppressed, and high moisture permeability and air permeability are maintained even after being processed into the total heat exchanger element.
The contact angle of water on the surface on the fiber layer side is more preferably 55 ° or more, and further preferably 60 ° or more.
The upper limit of the contact angle is not particularly limited, but is preferably 150 ° or less, more preferably 130 ° or less, and still more preferably 110 ° or less from the viewpoint of the coating property of the adhesive.
The contact angle means the contact angle to water 0.1 seconds after dropping, and is measured by the method described in the examples.

When the fiber layer containing the fine cellulose fiber is provided, the contact angle of water on the surface on the fiber layer side is generally less than 50 ° if the metal-containing compound such as the moisture absorbent is not contained. It is considered that this is because the capillary action of the fine cellulose fiber reduces the contact angle of water.
In order to make the contact angle of water on the surface on the fiber layer side into the above range, as described above, the fine cellulose fiber has an ionic group, and the fiber layer has a cross-linked structure with the ionic group It is preferable to contain a hygroscopic agent having a metal atom capable of forming a (cross-linked structure).
Thereby, it is presumed that a crosslinked structure (including a pseudo crosslinked structure) is formed, as a result of which the surface becomes hydrophobic and the contact angle is improved.

When the contact angle of water on one surface of the total heat exchanger sheet is D1 and the contact angle of water on the other surface is D2, the ratio D1 / D2 of the two is preferably 0.25 or more. The following is more preferable 0.3 or more and 3 or less, more preferably 0.5 or more 2 or less.
When D1 / D2 is in the above range, the difference in the contact angle of water between one surface and the other surface is small, which is preferable because the assembly of the element for all heat exchangers is easy.
In the case where the total heat exchange sheet uses paper as a substrate and has a two-layer structure of a substrate layer and a fiber layer, generally the contact angle of the surface on the fiber layer side is small, and the substrate layer side The contact angle of the surface of is large.

The air permeability of the total heat exchanger sheet of the present invention is preferably high, preferably 500 sec or more, more preferably 1,000 sec or more, still more preferably 3,000 sec or more, from the viewpoint of separating air supply and exhaust. Still more preferably, it is 10,000 sec or more, still more preferably 25,000 sec or more.
The air permeability is measured by the method described in the examples.

The moisture permeability of the total heat exchanger sheet of the present invention is preferably high from the viewpoint of promoting the transfer of latent heat and improving the heat conductivity, preferably 2,800 g / (m ² · 24 hr) or more, more preferably 3,000g ^/ (m 2 · 24hr) or more, still more preferably 3,500g ^/ (m 2 · 24hr) or more.
The moisture permeability is measured by the method described in the examples.

The sheet for total heat exchangers of the present invention preferably has high carbon dioxide barrier properties (CO ₂ barrier properties) from the viewpoint of suppressing carbon dioxide in exhaust gas from being mixed into the charge air, as described in the Examples. The carbon dioxide concentration reduction rate measured by the method of is preferably 1.3% or less, more preferably 1.0% or less, still more preferably 0.8% or less, still more preferably 0.5% or less More preferably, it is 0.3% or less.

The sheet for total heat exchanger of the present invention may contain other components in the substrate layer or the fiber layer, and specifically, sizing agents, wet strength agents, surfactants, flame retardants Agents, antifungal agents, rust inhibitors, antiblocking agents and the like.
The fiber layer may contain the other components described above, but the total content of the fine cellulose fiber, the hygroscopic agent, and the water in the fiber layer is preferably relative to the total mass of the fiber layer. It is 90 mass% or more, More preferably, it is 95 mass% or more, More preferably, it is 97 mass% or more, and 100 mass% may be sufficient.

As surfactants, anionic surfactants such as alkyl sulfates, polyoxyethylene alkyl sulfates, alkyl benzene sulfonates, α-olefin sulfonates, alkyl trimethyl ammonium chloride, dialkyl dimethyl ammonium chloride, benzalko chloride And cationic surfactants such as aluminum; amphoteric surfactants such as trimethylglycine, alkyl dimethylamino acetic acid betaine and alkylamido dimethylamino acetic acid betaine; and nonionic surfactants such as alkyl polyoxyethylene ether and fatty acid glycerol ester.
Flame retardants include halogen flame retardants, red phosphorus, melamine phosphate, ammonium polyphosphate, melamine polyphosphate, melamine pyrophosphate, piperazine polyphosphate, piperazine pyrophosphate, guanidine phosphate, guanidine guanidine sulfamate (condensed) Examples thereof include phosphorus-based flame retardants such as phosphoric acid ester compounds and phosphazene compounds, nitrogen-based flame retardants such as melamine cyanurate, metal hydroxides such as magnesium hydroxide and aluminum hydroxide, phosphinates and diphosphinates.

Examples of the fungicide include benzimidazole compounds, pyrithione compounds, iodopropenylbutyl carbamate compounds, isothiazolone compounds, organic nitrogen sulfur compounds and the like.
As the rust inhibitor, a water-soluble rust inhibitor is preferable, and examples thereof include alkali metal salts of aliphatic carboxylic acids and piperazine derivatives such as monohydroxymonoethyl piperazine.
Examples of the antiblocking agent include waxes selected from polyethylene wax, zinc stearate, polyethylene wax emulsion, polyethylene oxide wax, paraffin wax and the like, metal soaps such as silicone resin and higher fatty acid calcium salt, etc. Be

When producing the sheet for total heat exchangers of the present invention, if necessary, it may further have a calendering step for the purpose of post-processing as coating treatment or chemical treatment, adjustment of average thickness and thinning.
In the step of post-processing, for example, a coating solution of a flame retardant is prepared, and the step of coating and drying the coating solution is exemplified in the steps of spray coating, printing method, coating method and the like.
Moreover, the process of the calendering process which performs smoothing or thin film formation with a calender apparatus to the sheet | seat for total heat exchangers obtained can be provided, an average thickness can be adjusted, and density can be further improved. Examples of the calendering apparatus include a conventional calendering apparatus using a single press roll and a super calendering apparatus having a multi-staged structure. It is preferable to select these devices and the material (hardness of the material) and the linear pressure of each of both sides at the time of calendering according to the purpose. Specifically, the roll material may be appropriately selected from a combination of a metal roll and a resin roll with high hardness, a combination of a metal roll and a cotton roll, a combination of a metal roll and an amide roll, and the like.

[Element for total heat exchanger and total heat exchanger]
The total heat exchanger element of the present invention includes the above-described total heat exchanger sheet of the present invention, and in particular, as a liner of the total heat exchanger element.
More specifically, the total heat exchanger element sandwiches a spacer constituting a flow path between each sheet of the plurality of total heat exchanger sheets (liner), and the spacer and the sheet Are attached with an adhesive or the like.
Moreover, the total heat exchanger of this invention is equipped with the element for all heat exchangers of the said this invention. As a total heat exchanger used suitably, a stationary total heat exchanger is illustrated. The stationary total heat exchanger may be a cross flow type or a counter flow type, and is not particularly limited. The stationary total heat exchanger is an element for a total heat exchanger having a structure in which two flow paths independent of one another are partitioned by the total heat exchanger sheet (liner) according to the present invention, It is configured by combining fans.
By means of the air supply fan, the feed gas, such as ambient air, is drawn into the total heat exchanger element and contacts the total heat exchanger sheet incorporated in the total heat exchanger element. On the other hand, exhaust gas such as room air is sucked into the total heat exchanger element by the exhaust fan and similarly contacts the total heat exchanger sheet.
The feed gas and the exhaust gas, which are in contact via the total heat exchanger sheet, exchange heat through temperature and humidity. The heat-exchanged supply gas is blown into the air supply fan and taken, for example, into the room. On the other hand, the heat-exchanged exhaust gas is blown into an exhaust fan and discharged, for example, outdoors.
The sheet for total heat exchanger of the present invention has high moisture permeability and air permeability, and further has excellent carbon dioxide barrier properties, so it is excellent not only for sensible heat but also for latent heat exchange, and has high heat conductivity. Furthermore, mixing of the air supply and the exhaust is suppressed. Therefore, the total heat exchanger provided with the total heat exchanger sheet of the present invention is capable of efficient heat exchange. That is, it is possible to ventilate the air inside of which the carbon dioxide concentration has been increased while suppressing the release of heat or cold in the building, and to increase the efficiency of the total heat exchanger which maintains the heat effect by air conditioning and heating. be able to.

EXAMPLES The features of the present invention will be more specifically described below with reference to examples and comparative examples. The materials, amounts used, proportions, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Accordingly, the scope of the present invention should not be construed as limited by the specific examples shown below.

Example 1
<Production of Fine Cellulose Fiber>
(Phosphoric acid group introduction process)
Softwood kraft pulp manufactured by Oji Paper Co., Ltd. (solid content 93% by mass, basis weight 208 g / m ^{2 in} sheet form, as a raw material pulp, Canadian Standard Freeness Measured according to JIS P 8121: 2012 CSF) used 700 ml).
The raw material pulp was subjected to a phosphorylation treatment as follows.
First, a mixed aqueous solution of ammonium dihydrogen phosphate and urea is added to the above-mentioned raw material pulp, and 45 parts by mass of ammonium dihydrogen phosphate and 120 parts by mass of urea with respect to 100 parts by mass (absolute dry mass) of the raw material pulp It adjusted so that it might become 150 mass parts of water, and obtained the chemical | medical solution impregnation pulp. Next, the chemical-impregnated pulp obtained was heated for 200 seconds with a hot air drier at 165 ° C. to introduce a phosphoric acid group to the cellulose in the pulp to obtain a phosphorylated pulp.

(Washing process)
Next, the resulting phosphorylated pulp was subjected to a washing treatment.
The washing process is performed by pouring 10 L of ion-exchanged water with respect to 100 g (absolutely dry mass) of phosphorylated pulp, stirring to uniformly disperse the pulp to obtain a pulp dispersion, and repeating the filtration dewatering operation. went. When the electric conductivity of the filtrate became 100 μS / cm or less, it was regarded as the washing end point.

(Alkali treatment process)
Next, the phosphated pulp after washing was subjected to alkali treatment (neutralization treatment) as follows.
First, after diluting the phosphorylated pulp after washing with 10 L of ion exchanged water, a phosphated pulp slurry having a pH of 12 or more and 13 or less was obtained by gradually adding 1N aqueous sodium hydroxide solution while stirring. . Next, the phosphorylated pulp slurry was dewatered to obtain a phosphorylated pulp subjected to an alkali treatment (neutralization treatment).
Next, the above-mentioned washing treatment was performed on the phosphated pulp after the alkali treatment.
The phosphated pulp after alkali treatment thus obtained was subjected to measurement of infrared absorption spectrum using FT-IR. As a result, absorption attributable to phosphate groups was observed at around 1230 cm ^-1 , confirming that phosphate groups were added to the pulp. Moreover, the amount of phosphate groups (the amount of strongly acidic groups) measured by the above-mentioned measurement method was 1.45 mmol / g.
Moreover, when the obtained phosphorylated pulp was tested and analyzed by an X-ray diffractometer, it was found at two positions of 2θ = 14 ° or more and 17 ° or less and 2θ = 22 or more and 23 ° or less A typical peak was confirmed in cellulose type I crystals, and it was confirmed that cellulose type I crystals were contained.

(Disintegration process)
Ion-exchanged water was added to the phosphorylated pulp obtained through the above-mentioned alkali treatment step to prepare a slurry having a solid content concentration of 2% by mass. This slurry was treated twice with a wet atomization device (Starburst, manufactured by Sugino Machine Co., Ltd.) at a pressure of 200 MPa to obtain a fine cellulose fiber dispersion containing fine cellulose fibers. It was confirmed by X-ray diffraction that the fine cellulose fibers maintain cellulose type I crystals. The fiber width of the fine cellulose fiber was measured using a transmission electron microscope and found to be 3 to 5 nm.
Furthermore, when the yield of the fine cellulose fiber was measured according to the method mentioned above about the obtained fine cellulose fiber, the yield was 99.2%.

<Preparation of a sheet for total heat exchanger>
Pulp blended with NBKP (Needle bleached Kraft Pulp) and LBKP (Leaf Bleached Kraft Pulp) at 65:35 (mass ratio) is refined to 450 ml with Canadian Standard Freeness, aluminum sulfate 1.0 parts by mass, and 0.01 parts by mass of alkyl ketene dimer (size pine K-903-20, manufactured by Arakawa Chemical Industries, Ltd.) as a sizing agent were added to 100 parts by mass of pulp. Using this stock, high-quality paper with a basis weight of 60 g / m ^{2 was} produced by using a Fourdrinier multi-tubular paper machine.
Next, using the high-quality paper obtained above as a base material, on one side of the base material, the fine cellulose fiber dispersion obtained above is coated with a fine bared cellulose fiber (hereinafter referred to as CNF) after drying with a meyer bar It coated so that a coating amount may be 0.4 g / m < ² >, and the fiber layer was formed.
Next, impregnating and drying lithium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) as a moisture absorbent with a mangle roll so that the coating weight (coating amount) after drying is 3.9 g / m ² , A sheet for total heat exchanger was prepared. The basis weight of this total heat exchanger sheet was 73 g / m ² and the water content was 10% by mass.

Example 2
Example 1 was repeated except that in place of lithium chloride, calcium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) was impregnated and dried so that the coated amount after drying was 4.9 g / m ^2. A total heat exchanger sheet was prepared in the same manner. The basis weight of this total heat exchanger sheet was 73 g / m ² and the water content was 10% by mass.

[Example 3]
In Example 1, the fine cellulose fiber dispersion is coated so that the coated amount of the fine cellulose fiber (CNF) after drying is 0.8 g / m ^2, and then lithium chloride (Wako Pure Chemical Industries, Ltd. as a moisture absorbent) A sheet for a total heat exchanger was produced in the same manner as in Example 1 except that impregnation and drying were performed so that the mass after drying was set to 5.2 g / m ² . The basis weight of this total heat exchanger sheet was 78 g / m ² and the water content was 12% by mass.

Example 4
Example 3 is repeated except that in place of lithium chloride, calcium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) is impregnated and dried so that the coated amount after drying is 6.0 g / m ^2. A total heat exchanger sheet was prepared in the same manner. The basis weight of this total heat exchanger sheet was 76 g / m ² and the water content was 10% by mass.

[Example 5]
A pulp containing NBKP and LBKP at 50: 50 (mass ratio) is beaten to 170 ml with Canadian Standard Freeness, 1.0 part of aluminum sulfate, 0.01 part of alkyl ketene dimer as sizing agent (size pine K-903- 20, Arakawa Chemical Industries Co., Ltd. product, 0.15 parts of wet paper strength agent (Arafix 255, Arakawa Chemical Co., Ltd. product) were added with respect to 100 mass parts of pulp. Using this stock, a semi-glassine paper having a basis weight of 40 g / m ² was produced by using a Fourdrinier multi-tubular paper machine.
Then, using the obtained semi-glassine paper as a base material and using one side of the base material in the same manner as in Example 1, a fine cellulose fiber dispersion is dried with a mayer bar of fine cellulose fiber (CNF) It coated so that a coating amount might be 0.4 g / m < ² >, and formed the fiber layer.
Subsequently, lithium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) as a hygroscopic agent is impregnated and dried with a mangle roll so that the coated amount after drying is 5.6 g / m ² to prepare a sheet for total heat exchanger did. The basis weight of the total heat exchanger sheet was 60 g / m ² , and the water content was 17% by mass.

[Example 6]
Example 5 is the same as Example 5 except that calcium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) is impregnated and dried so that the coated amount after drying is 5.0 g / m ^{2 in place of} lithium chloride. A total heat exchanger sheet was prepared in the same manner. The basis weight of this total heat exchanger sheet was 58 g / m ² , and the water content was 17% by mass.

Comparative Example 1
A total heat exchanger sheet was produced in the same manner as in Example 1 except that water was coated and impregnated in place of the fine cellulose fiber dispersion and the hygroscopic agent in Example 1. The basis weight of the total heat exchanger sheet was 60 g / m ² , and the water content was 5% by mass.

Comparative Example 2
A sheet for a total heat exchanger was produced in the same manner as in Example 1 except that the absorbent was replaced with water and impregnated in Example 1. The basis weight of the total heat exchanger sheet was 63 g / m ² and the water content was 4% by mass.

Comparative Example 3
A total heat exchanger sheet was produced in the same manner as in Example 5 except that water was applied and impregnated in place of the fine cellulose fiber dispersion and the hygroscopic agent in Example 5. The basis weight of this total heat exchanger sheet was 40 g / m ² , and the water content was 5% by mass.

Comparative Example 4
A sheet for a total heat exchanger was produced in the same manner as in Example 5 except that the absorbent was replaced with water and impregnated in Example 5. The basis weight of this total heat exchanger sheet was 41 g / m ² , and the water content was 3% by mass.

[Evaluation and analysis]
<Water content (water content)>
The water content (hereinafter, also simply referred to as the water content) of the substrate and the obtained total heat exchanger sheet was measured in accordance with JIS P 8127: 2010.

<Basic weight>
The basis weight of the total heat exchanger sheet was measured in accordance with JIS P 8124: 2011.

<Thickness>
The thickness of the total heat exchanger sheet was measured in accordance with JIS P 8118: 2014.

<Density>
The density of the sheet for all heat exchangers was calculated from the basis weight and the paper thickness obtained by the measurement method described above.

<Water contact angle>
According to JIS R 3257: 1999, 4 μL of distilled water is dropped on the surface of the total heat exchanger sheet using a dynamic water contact angle tester (manufactured by Fibro, 1100 DAT), and water after 0.1 seconds after dropping The contact angle was measured. The measurement was performed on each of the surface on the fiber layer side (CNF surface) and the surface on the substrate layer side (back surface).

<Air permeability>
JAPAN TAPPI Pulp and Paper Testing Method No. The air permeability of the total heat exchanger sheet was measured in accordance with the 5-2: 2000 Oken type air permeability method.

<CO2 barrier property>
Measuring device in which a carbon dioxide (CO ₂ ) analyzer is installed inside a cubic container made of acrylic having a square window section of 20 cm on each side at the center of each of 4 side surfaces and 1 top surface And
In a state where a 25 cm square total heat exchanger sheet is attached to each window of the measuring apparatus, 5,000 ppm of carbon dioxide is enclosed in a container, and the concentration of CO ₂ is 15 at 20 ° C. × 65% conditions. The measurement was performed 4 times every minute for a total of 1 hour.
From the measured values after 15 minutes, 30 minutes, 45 minutes and 60 minutes, the reduction rate of the carbon dioxide concentration at each time point is determined, the average is further determined, and the carbon dioxide concentration reduction rate of the measured sample is obtained. . As the carbon dioxide concentration reduction rate is lower, the total heat exchanger sheet is more excellent in carbon dioxide (CO ₂ ) barrier properties.
A carbon dioxide concentration reduction rate of 1.3% or less is suitably used as a sheet for total heat exchangers.

Moisture permeability
It was measured in accordance with JIS Z 0208: 1976 under conditions of 20 ° C. × 65% RH.
However, the moisture permeability was calculated as follows.
The mass increment (g) one hour after the start of the test is A, and the mass increment (g) from one hour to two hours after the start of the test is B, and the mass increment C per hour is calculated by the following formula (1) The The moisture permeability sheet (m / (m ² · 24 h)) was determined by converting this value to a value of 1 m ^{2 of} the moisture permeable sheet per 24 hours.
Mass increment per hour C = (A + B) / 2 (1)
The results of Examples and Comparative Examples are shown in Table 1 below.

The sheet for total heat exchangers of the present invention has high moisture permeability and air permeability, and is also excellent in carbon dioxide barrier properties. Therefore, a total heat exchanger that is suitably used as a liner for a total heat exchanger element and configured using the total heat exchanger element has high carbon dioxide barrier properties and heat exchange properties.

Claims

A substrate layer,
And a fiber layer provided on the substrate layer,
The fiber layer contains fine cellulose fibers having a fiber width of 1,000 nm or less,
The water content is at least 8% by mass,
Seat for total heat exchanger.
The total heat exchanger sheet according to claim 1, further comprising a hygroscopic agent.
The whole of claim 2, wherein the hygroscopic agent comprises at least one selected from metal halides, metal sulfates, metal acetates, amine salts, phosphoric acid compounds, guanidine salts, and metal hydroxides. Heat exchanger sheet.
The sheet | seat for total heat exchangers of Claim 2 or 3 whose content of the said hygroscopic agent with respect to 100 mass parts of said fine cellulose fibers is 100 mass parts or more.
The total heat exchanger sheet according to any one of claims 1 to 4, wherein the fine cellulose fibers have an ionic group.
The total heat exchanger sheet according to any one of claims 1 to 5, wherein a contact angle of water on the surface on the fiber layer side is 50 ° or more.
The contact angle of water on one surface of the total heat exchanger sheet is D1, and the contact angle of water on the other surface is D2, D1 / D2 is 0.25 or more and 4 or less. The sheet for all heat exchangers described in any one.
The total heat exchanger sheet according to any one of claims 1 to 7, wherein the fiber width of the fine cellulose fibers is 30 nm or less.
The sheet for total heat exchangers according to any one of claims 1 to 8, wherein the basis weight of the fine cellulose fibers is 0.1 g / m 2 or more and 3 g / m 2 or less.
A total heat exchanger element comprising the total heat exchanger sheet according to any one of claims 1 to 9.
A total heat exchanger comprising the element for total heat exchanger according to claim 10.