JP2015059286A - Paper for total heat exchange element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide paper for total heat exchange elements which is high in ventilation capacity and wet-heat exchange capacity and excellent in flame retardancy and is suppressed in shape change on moisture absorption.SOLUTION: Paper for total heat exchange elements is applied with a moisture absorber and has an air permeability of 0.13 μm/(Pa S) or lower, by JIS P8117, a water vapor permeability of 300 g/m24h or higher at 23°C and a relative humidity of 50%, by JIS Z0208 and a ratio of vertical-direction orientation strength/lateral-direction orientation strength of 1.0-1.8, more preferably a ratio of vertical-direction orientation strength/lateral-direction orientation strength of 1.0-1.5.

Description

  In order to maintain a comfortable space in buildings, offices, stores, residences, etc., the present invention supplies sensible heat that is installed in a total heat exchanger that supplies fresh outside air and exhausts indoor dirty air. The present invention relates to a total heat exchange element sheet used for a total temperature exchange element of (temperature) and latent heat (humidity). More specifically, the present invention relates to a total heat exchange element paper that can provide a total heat exchange element that is excellent in ventilation performance, wet heat exchange performance, and flame retardancy, and that is less deformed by moisture absorption.

  As shown in FIG. 1, the total heat exchange element 1 is formed by alternately laminating a flat total heat exchange element sheet 2 and a spacer 3 processed into a wave shape using a corrugator. Molded. In FIG. 1, the arrows indicate the flow of fresh outside air and dirty air in the room. The total heat exchange element 1 performs wet heat exchange while suppressing the movement of air facing the flat total heat exchange element paper 2. Moreover, since it is used for a building, it is also necessary to have a flame retardance.

  In recent years, a total heat exchange element with high wet heat exchange efficiency has been demanded in order to obtain a greater effect with less electric power from the viewpoints of amendment of building laws, lifestyle changes, and environmental protection.

  Conventionally, for the purpose of imparting such characteristics, a total heat exchange element paper (for example, see Patent Documents 1 and 2) in which a moisture absorbent or a flame retardant is applied to paper obtained by beating natural pulp has been developed. Although it excels in ventilation performance and wet heat exchange performance, the expansion and contraction of the paper increases due to moisture absorption, and the total heat exchange element is likely to be deformed. Noise generation, ventilation performance, and wet heat exchange performance during total heat exchanger operation There is also a problem that adversely affects itself.

  In order to solve such a problem, a method of applying a moisture absorbing / releasing agent in which silica gel and aluminum hydroxide are mixed without using a moisture absorbing agent has been studied (for example, see Patent Document 3). However, with this method, it is not possible to achieve the high wet heat exchange efficiency that has been demanded in recent years.

International Publication No. 2002/099193 Pamphlet JP 2005-325473 A Japanese Patent Laid-Open No. 10-212691

  In view of the current situation, an object of the present invention is to provide a total heat exchange element paper that can provide a total heat exchange element that has high ventilation performance and wet heat exchange performance, is excellent in flame retardancy, and has little shape change during moisture absorption. It is.

The first means of the present invention is that a hygroscopic agent is applied to a base sheet, the air permeability according to JIS P8117 is 0.13 μm / (Pa · S) or less, 23 ° C. according to JIS Z0208, Total heat exchange element paper having a moisture permeability of 300 g / m ² · 24 h or more at a relative humidity of 50% and a ratio of longitudinal orientation strength / lateral method orientation strength of 1.0 to 1.8. . It is possible to provide a total heat exchange element paper that solves the above problems and that provides a total heat exchange element that has high ventilation performance and wet heat exchange performance, excellent flame retardancy, and little shape change during moisture absorption.

  The second means of the present invention is a total heat exchange element sheet having a ratio of longitudinal orientation strength / lateral method orientation strength of 1.0 to 1.5 or less. It is possible to provide a total heat exchange element paper having high ventilation performance and wet heat exchange performance, excellent flame retardancy, and less change in shape upon moisture absorption.

  As a result of intensive studies, the present inventors have found that the deformation of the total heat exchange element is caused by the difference in elongation during moisture absorption in the vertical direction and the horizontal direction of the total heat exchange element sheet. As shown in FIG. 1, the structure of the total heat exchange element is formed by alternately laminating single-stage sheets that are corrugated and bonded to each other in a perpendicular direction. As the total heat exchange element paper, the vertical and horizontal directions are alternately stacked. The total heat exchange element paper using natural pulp that has been highly beaten as in the present invention has a large lateral expansion and contraction compared to general paper, and therefore the molded total heat exchange element is laminated when absorbing moisture. Every time, the size of the vertical and horizontal dimensional elongations are changed, and the entire heat exchange element as a whole undergoes a complicated dimensional change, so that it deforms significantly. The present inventors have found that the difference in expansion and contraction between the longitudinal direction and the lateral direction of the total heat exchange element paper greatly depends on the aspect ratio of the orientation strength of the fibers. That is, in order to reduce the change in shape of the total heat exchange element during moisture absorption, the ratio of the longitudinal orientation strength / lateral method orientation strength of the total heat exchange element paper constituting the total heat exchange element is reduced. It has been found that this has been achieved and has led to the present invention. Further, although the reason is not clear, the present inventors have found that the ratio of longitudinal orientation strength / lateral direction orientation strength also affects flame retardancy, leading to the present invention.

  According to the present invention, it is possible to provide a total heat exchange element sheet that provides a total heat exchange element that has high ventilation performance and wet heat exchange performance, excellent flame retardancy, and little shape change upon moisture absorption.

It is a total heat exchange element explanatory drawing. It is explanatory drawing in case the ratio of the longitudinal direction orientation intensity | strength / lateral method orientation intensity | strength of a total heat exchange element paper is large. It is explanatory drawing in case the ratio of the longitudinal direction orientation intensity | strength / transverse method orientation intensity | strength of a total heat exchange element paper is small.

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

  The base sheet in the present invention is generally produced by a wet method using natural pulp as a raw material. The natural pulp used is preferably a single or a combination of wood pulp fibers such as LBKP, NBKP, LBSP, NBSP, NUKP. In addition, plant fibers such as cotton, hemp, bamboo, sugar cane, corn and kenaf, animal fibers such as wool and silk, and cellulose regenerated fibers such as rayon, cupra and lyocell can be used alone or in combination. .

  The above fibers are appropriately beaten by a beating device such as a double disc refiner, deluxe finner, jordan, conical refiner, etc. in order to increase the bond strength between the fibers, maintain the sheet shape, and enhance the air shielding properties. The air permeability measured in accordance with JIS P8117 is adjusted to 0.13 μm / (Pa · S) or less. The air permeability is more preferably 0.08 μm / (Pa · S) or less, and further preferably 0.02 μm / (Pa · S) or less. The freeness is preferably a Canadian modified freeness defined below and adjusted to 150 ml or less.

  Canadian modified freeness: Value measured according to JIS P 8121 Canadian standard freeness test method, except that 0.5g of pulp was completely dried and the sieve plate was made into 80 mesh plain weave bronze wire. .

  In addition, these fibers have various fillers such as heavy calcium carbonate, light calcium carbonate, kaolin, talc, clay, titanium dioxide, aluminum hydroxide, silica, alumina, organic pigments, and adhesives for the purpose of enhancing shielding properties. In addition, various compounding agents such as a sizing agent, a fixing agent, a yield agent, and a paper strength enhancer can be suitably contained according to each step and each material.

  As a manufacturing method for forming each fiber into a sheet shape, it is formed into a sheet shape using a general long net paper machine, a round net paper machine or the like.

  The base sheet may be subjected to a surface size press with a size press, a roll coater or the like installed in the paper machine for the purpose of obtaining the necessary shielding properties. As components of the surface size press solution, starch purified from natural plants, hydroxyethylated starch, oxidized starch, etherified starch, phosphate esterified starch, enzyme-modified starch and cold water soluble starch obtained by flash drying them, Various synthetic binders such as polyvinyl alcohol can be used as appropriate.

  The ratio of the longitudinal orientation strength / lateral method orientation strength of the total heat exchange element paper in the present invention depends on the ratio of the longitudinal orientation strength / lateral method orientation strength of the base material sheet to which the flame retardant and the hygroscopic agent are applied. It is determined. The ratio of the longitudinal direction orientation strength / lateral direction orientation strength of the base sheet is determined by the J / W ratio (discharge speed from the fiber raw material dispersion liquid discharger called head box / fiber raw material dispersion called wire) in the paper making process. The traveling speed of the supporting net that supports and dehydrates moderately). In addition, by using an amplitude device that reciprocates a wire called a shaking device in a direction perpendicular to the traveling direction, the ratio of longitudinal orientation strength / lateral orientation strength can be further reduced.

  Here, the orientation strength in the present invention is the transmission speed of ultrasonic waves in the surface direction of the base sheet, and is measured using a dedicated device.

  The ratio of longitudinal orientation strength / lateral orientation strength of the total heat exchange element paper in the present invention is 1.0 to 1.8, more preferably 1.0 to 1.5, and 1.1 to 1 .4 is more preferred. When it exceeds 1.8, the shape change at the time of moisture absorption of a total heat exchange element becomes large, and there exists a tendency for a flame retardance to fall, and it is unpreferable.

  The shape change at the time of moisture absorption of a total heat exchange element is demonstrated using FIG. 2 and FIG. FIG. 2 is an explanatory diagram when the ratio of longitudinal orientation strength / lateral method orientation strength is large. FIG. 3 is an explanatory diagram when the ratio of longitudinal orientation strength / lateral method orientation strength is small. When the ratio of longitudinal orientation strength / lateral method orientation strength is large and exceeds 1.8, the dimensional change in the horizontal direction during moisture absorption is large, and the dimensional change in the vertical direction is small. That is, since the difference in dimensional change between the vertical direction and the horizontal direction is large, the shape change during moisture absorption of the total heat exchange element becomes large, which is not preferable. On the other hand, if the ratio of longitudinal orientation strength / lateral orientation strength is small and 1.0 to 1.8, the difference in dimensional change between the vertical direction and the horizontal direction when moisture is absorbed is small, so the shape change when absorbing moisture. Can be suppressed, which is preferable.

  In the present invention, a coating layer may be provided in order to fill the gaps in the base sheet and enhance air shielding properties. For the coating layer, calcium carbonate, kaolin, synthetic silica, colloidal silica, talc, satin white, lithopone, titanium dioxide, alumina, aluminum hydroxide, zinc oxide, magnesium carbonate, organic pigments, or cation modified as fillers Or a composite of two or more of these. Moreover, in order to maintain the adhesiveness of a base material sheet and a coating layer and coating layer intensity | strength, you may add a binder component. As the binder component, styrene butadiene based synthetic rubber latex, modified starch, polyvinyl alcohol, or the like can be used alone or in combination.

  The base sheet provided with the coating layer may be subjected to a calendering treatment in order to obtain the required density, smoothness and air permeability. As the calendar device, a device composed of a combination of hard rolls, elastic rolls, a pair of hard rolls and elastic rolls is preferably used, and a machine calender, soft nip calender, super calender, multi-stage calender, multi-nip calender, etc. are used. can do.

  In the present invention, commercially available glassine paper, condenser paper, or the like can be used as long as the air permeability and the ratio of longitudinal orientation strength / lateral direction orientation strength are satisfactory.

For the purpose of imparting flame retardancy, a flame retardant can be impregnated or applied to the base sheet with adjusted air permeability and fiber orientation angle. Examples of the flame retardant include an inorganic flame retardant, an inorganic phosphorus compound, a nitrogen-containing compound, a chlorine compound, and a bromine compound. For example, a mixture of borax and boric acid, aluminum hydroxide, antimony trioxide, ammonium phosphate, ammonium polyphosphate, ammonium sulfamate, guanidine sulfamate, guanidine phosphate, phosphate amide, chlorinated polyolefin, ammonium bromide, Examples include flame retardants that are dispersible in aqueous solutions or water such as non-ether type polybromo cyclic compounds. As the level of flame retardancy, the carbonization length measured according to JIS A1322 is preferably less than 10 cm, and the coating amount of the flame retardant is preferably 5 g / m ² or more.

  Moreover, in order to improve wet heat exchange efficiency, a hygroscopic agent can be impregnated or applied. Hygroscopic agents include inorganic acid salts, organic acid salts, inorganic fillers, polyhydric alcohols, ureas, hygroscopic (water absorbing) polymers, and examples of inorganic acid salts include lithium chloride, calcium chloride, chloride Magnesium, organic acid salt as sodium lactate, calcium lactate, sodium pyrrolidonecarboxylate, inorganic filler as aluminum hydroxide, calcium carbonate, aluminum silicate, magnesium silicate, talc, clay, zeolite, diatomaceous earth, sepiolite, silica gel, Activated carbon, polyhydric alcohols are glycerin, ethylene glycol, triethylene glycol, polyglycerin, ureas are urea, hydroxyethylurea, polymers are polyaspartic acid, polyacrylic acid, polyglutamic acid, polylysine, alginic acid, carboxy Mechi Cellulose, hydroxyalkyl cellulose and salts or cross-linked products thereof, carrageenan, pectin, gellan gum, agar, xanthan gum, hyaluronic acid, guar gum, gum arabic, starch and cross-linked products thereof, polyethylene glycol, polypropylene glycol, collagen, acrylonitrile weight Saponified coal, starch / acrylate graft copolymer, saponified vinyl acetate / acrylate copolymer, starch / acrylonitrile graft copolymer, acrylate / acrylamide copolymer, polyvinyl alcohol / maleic anhydride Examples include hygroscopic agents such as copolymers, polyethylene oxide, isobutylene-maleic anhydride copolymers, and polysaccharide / acrylate graft self-crosslinked products. Select the type and amount of adhesion according to the desired moisture permeability. so It is needed.

The amount of the hygroscopic agent applied depends on the type of the hygroscopic agent to be used, but the value measured under strict conditions for exchanging humidity at 23 ° C. and 50% relative humidity according to JIS Z0208 is 300 g / m ² -If it is 24h or more, the total heat exchange element excellent in the wet heat exchange performance can be obtained. The application amount of the hygroscopic agent is preferably 2.0 g / m ² or more, more preferably 3.0 g / m ² or more, and further preferably 4.0 g / m ² or more.

Hereinafter, the present invention will be described in detail according to examples. In addition, this invention is not limited to an Example. The parts and% in the following are by mass unless otherwise specified. Moreover, the value which shows a coating amount is the mass after drying, unless there is a notice.

Example 1
Softwood bleached kraft pulp (NBKP) was disaggregated at a concentration of 3% and then beaten using a double disc refiner until the freeness of the pulp reached 100 ml. Thereafter, a J / W ratio was adjusted with a long paper machine to produce a base sheet having a ratio of longitudinal orientation strength / lateral direction orientation strength of 1.8 and basis weight of 40 g / m ² . Then, after applying 6 g / m ^{2 of} guanidine sulfamate flame retardant as a solid content using an impregnation processing machine, 2.1 g / m ^{2 of} lithium chloride was further applied as a hygroscopic agent. An exchange element paper was prepared.

(Example 2)
The total heat exchange element paper of Example 2 was treated in the same manner as in Example 1 except that beating was performed until the freeness of the pulp reached 20 ml, and 4.1 g / m ^{2 of} lithium chloride was applied as a moisture absorbent. Produced.

(Example 3)
In the same manner as in Example 1, except that the ratio of longitudinal orientation strength / lateral direction orientation strength was 1.7 by adjusting the J / W ratio with a long paper machine. A total heat exchange element paper was prepared.

Example 4
In the same manner as in Example 1, except that the ratio of longitudinal orientation strength / lateral direction orientation strength was 1.6 by adjusting the J / W ratio with a long paper machine. A total heat exchange element paper was prepared.

(Example 5)
In the same manner as in Example 2, except that the ratio of longitudinal orientation strength / lateral orientation strength was 1.5 by adjusting the J / W ratio with a long paper machine. A total heat exchange element paper was prepared.

(Example 6)
In the same manner as in Example 2, except that the ratio of longitudinal orientation strength / lateral orientation strength was 1.0 by adjusting the J / W ratio with a long paper machine. A total heat exchange element paper was prepared.

(Example 7)
A total heat exchange element paper of Example 7 was produced in the same manner as in Example 1 except that beating was performed until the freeness of the pulp reached 120 ml.

(Comparative Example 1)
In the same manner as in Example 1 except that the ratio of longitudinal orientation strength / lateral orientation strength was adjusted to 1.9 by adjusting the J / W ratio with a long paper machine. A total heat exchange element paper was prepared.

(Comparative Example 2)
A total heat exchange element paper of Comparative Example 2 was produced in the same manner as in Example 1 except that the freeness of the pulp was 150 ml.

(Comparative Example 3)
A total heat exchange element sheet of Comparative Example 3 was produced in the same manner as in Example 1 except that 1.5 g / m ^{2 of} lithium chloride was applied as a moisture absorbent.

<Air permeability>
The air permeability was measured according to JIS P 8117's Oken air permeability resistance test method. If the total heat exchange element paper is 0.13 μm / (Pa · S) or less, a total heat exchange element having excellent ventilation performance can be obtained.

<Moisture permeability>
In accordance with the moisture permeability test method of JIS Z 0208, the moisture permeability was measured under the conditions of a temperature of 23 ° C. and a relative humidity of 50%.

<Carbonation length>
According to the flame retardancy test method of JIS A 1322, the carbonization length was measured under the condition of a heating time of 3 minutes.

<Ratio of longitudinal orientation strength / lateral orientation strength>
Using an orientation angle measuring device SST-3000 (manufactured by Nomura Shoji Co., Ltd.), the ultrasonic transmission speeds in the vertical and horizontal directions of the total heat exchange element paper were measured and calculated as the vertical measurement value / horizontal measurement value.

<Deformation of total heat exchange element>
Using the total heat exchange elements of Examples 1 to 7 and Comparative Examples 1 to 3, total heat exchange elements having a length of 200 mm, a width of 200 mm, a height of 250 mm, and a single height of 4 mm were produced. As a spacer, 70 g / m ² bleached kraft paper was used. This total heat exchange element was allowed to stand for 48 hours under the conditions of 30 ° C. and 90% relative humidity, and the shape change was visually evaluated.

A: Level with almost no change in shape.
○: Although there is some change in shape, there is no problem in actual use.
X: Level at which the shape change clearly occurs and there is a problem in actual use.

  The results are shown in Table 1.

<Evaluation results>
From the results of Examples 1 to 7, a hygroscopic agent was applied, the air permeability according to JIS P8117 was 0.13 μm / (Pa · S) or less, and 23 ° C. and relative humidity according to JIS Z0208. In a total heat exchange element paper having a moisture permeability of 300 g / m ² · 24 h or more in a 50% condition, when the ratio of longitudinal orientation strength / lateral orientation strength of the paper is 1.0 to 1.8, It is apparent that a total heat exchange element sheet having excellent flame retardancy and little change in shape when the total heat exchange element absorbs moisture can be obtained. When the ratio of the longitudinal direction orientation strength / lateral direction orientation strength of the paper is 1.0 to 1.5, it is possible to obtain a total heat exchange element paper in which the shape change at the time of moisture absorption of the total heat exchange element is further reduced. it is obvious.

On the other hand, in Comparative Example 1, since the ratio of longitudinal orientation strength / lateral orientation strength exceeded 1.8, the shape change during moisture absorption of the total heat exchange element was large. Moreover, carbonization length also became long and was a level which has a problem in a flame retardance. In Comparative Example 2, the air permeability exceeds 0.13 μm / (Pa · S), and in Comparative Example 3, the moisture permeability is less than 300 g / m ² · 24 h. There was a tendency that the shape change slightly increased and the carbonization length also increased.

  The total heat exchange element paper according to the present invention supplies a fresh outside air and also performs a total heat exchange of a total heat exchanger that exchanges sensible heat (temperature) and latent heat (humidity) when exhausting dirty air in the room. Used for devices.

1 Total heat exchange element 2 Total heat exchange element paper 3 Spacer

Claims (2)

Moisture absorbent is applied to a base sheet, and the air permeability according to JIS P8117 is 0.13 μm / (Pa · S) or less, and the moisture permeability is 23 ° C. and 50% relative humidity according to JIS Z0208. There is a 300 g ^/ m 2 · 24h or more, the total heat exchange element sheets ratio of machine direction orientation intensity / horizontal process orientation strength is characterized in that 1.0 to 1.8.   The total heat exchange element paper according to claim 1, wherein the ratio of longitudinal orientation strength / lateral method orientation strength is 1.0 to 1.5 or less.

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