JP5224873B2 - Sheet material for dehumidification and filter material for dehumidification - Google Patents

Description

  The present invention relates to a dehumidifying sheet material capable of absorbing and releasing moisture and a dehumidifying filter material comprising the sheet material.

  The desiccant air conditioner is an air conditioner that generates low-humidity air by using a moisture adsorbent. By supplying low-humidity air, comfort can be sufficiently obtained even if the temperature is not so low. This desiccant air conditioner has an air supply fan for introducing air from the outside into the room, a dehumidification rotor for dehumidification by adsorbing moisture in the supply air, and a cooling for cooling the dehumidified air. A regenerator, a heater for regenerating the dehumidification rotor by removing moisture adsorbed on the dehumidification rotor, and a regeneration fan for exhausting indoor air to the outside. The dehumidification rotor is obtained by processing a dehumidification filter material containing a moisture adsorbent into a rotor. By rotating the dehumidification rotor, the adsorption zone that adsorbs moisture of the processing air and the regeneration zone that removes the adsorbed moisture at a high temperature are sequentially passed.

  As the moisture adsorbent for dehumidifying filter materials, high water absorption polymers, organic moisture adsorbents such as carboxymethylcellulose, inorganic materials such as sepiolite, zeolite, bentonite, attapulgite, diatomaceous earth, activated carbon, porous silica, aluminum hydroxide, etc. Although a moisture adsorbent is used, especially porous silica is widely used because it has a large amount of adsorption and is inexpensive. As a method for producing a filter material for dehumidification using porous silica, for example, inorganic fiber paper is formed into a honeycomb shape and then fired at a high temperature to remove organic substances and impregnated in a coating solution containing porous silica. Post-high temperature drying methods and methods of impregnating ceramic fiber paper with water glass to produce silica gel have been proposed (see, for example, Patent Documents 1 and 2). Moreover, the method of processing the sheet-like material which consists of a water | moisture-content adsorption agent and various fibers into the filter material for dehumidification is proposed (for example, refer patent documents 3-6).

However, in the adsorption zone of the desiccant air conditioner, the temperature of the processing air and the dehumidifying filter material rises by 20 to 35 ° C. due to the heat of adsorption of these moisture adsorbents. The adsorbent immediately desorbed moisture in the adsorption zone, and there was a problem that dehumidified air could not be obtained efficiently.
JP-A-6-226037 Japanese Patent Laid-Open No. 5-115737 Japanese Patent Laid-Open No. 10-212691 Japanese Patent Laid-Open No. 11-189999 JP 2003-38928 A JP 2004-268020 A

  An object of the present invention is to provide a sheet material for dehumidification and a filter material for dehumidification that can suppress moisture desorption caused by a temperature increase due to heat of adsorption.

As a result of earnest examination,
(1) (a) porous silica, Ri Na contain at least (b) hygroscopic salt, (a) the content of (b) hygroscopic salt to porous silica is 20 to 130 wt%, ( b) dehumidification sheet that uses a guanidine salt as a hygroscopic salt,
( 2 ) The sheet-like material for dehumidification according to (1), further comprising (c) an organic fiber and (d) a cellulose-based fibrillated fiber,
( 3 ) (c) The sheet-like material for dehumidification according to the above ( 2 ), comprising at least a heat-fusible organic fiber as the organic fiber,
( 4 ) (c) As the organic fiber, (c1) an organic fiber having a fineness of 0.01 dtex or more and 0.30 dtex or less, (c2) an organic fiber having a fineness of more than 0.30 dtex but not more than 0.45 dtex, (c3) a fineness of 0. The sheet-like material for dehumidification according to the above ( 2 ), comprising at least two kinds selected from organic fibers exceeding 45 dtex and not more than 2.5 dtex,
( 5 ) It has been found that the above problems can be solved by a dehumidifying filter material containing the dehumidifying sheet material according to any one of (1) to ( 4 ).

  The sheet material for dehumidification of the present invention contains (a) porous silica as a moisture adsorbent and further contains (b) a hygroscopic salt. (A) When the porous silica adsorbs moisture, the desorption of moisture starts immediately due to the temperature rise due to the heat of adsorption. In the dehumidifying sheet of the present invention, (a) it exists on the surface of the porous silica ( b) Moisture that has been desorbed from the porous silica is retained by the hygroscopic salt. Moreover, (b) since the hygroscopic salt has a large specific heat, it is possible to suppress an increase in temperature due to the heat of adsorption of the dehumidifying sheet. When these two effects are synergistically expressed and the dehumidifying filter material comprising the dehumidifying sheet material of the present invention is used, for example, in a desiccant air conditioner, the desorption of moisture in the adsorption zone is performed. It is suppressed and dehumidified air can be obtained efficiently.

The sheet material for dehumidification of the present invention comprises (a) porous silica and (b) a hygroscopic salt. Examples of (a) porous silica include silica gel, silica alumina amorphous porous body, and mesoporous silica. (A) The preferable specific surface area of the porous silica is 400 to 800 m ² / g, and the preferable average maximum pore diameter is 1 to 7 nm, more preferably 3 to 7 nm.

  (B) Specific examples of hygroscopic salts include metal halides such as lithium chloride, calcium chloride, magnesium chloride, and aluminum chloride, metal sulfates such as sodium sulfate, calcium sulfate, magnesium sulfate, and zinc sulfate, and potassium acetate. Metal acetates such as dimethylamine hydrochloride, phosphoric acid compounds such as orthophosphoric acid, guanidine hydrochloride, guanidine phosphate, guanidine sulfamate, guanidine salts such as methylol phosphate guanidine, guanidine carbonate, potassium hydroxide, water Examples thereof include metal hydroxides such as sodium oxide and magnesium hydroxide. Among these, when metal halide salt and guanidine salt are used, dehumidified air can be obtained more efficiently. In addition, some halogenated metal salts and metal hydroxides such as lithium chloride, potassium hydroxide, and sodium hydroxide may dissolve porous silica (a), so guanidine salts may be used. preferable.

  By the way, in general, (b) a hygroscopic salt is a material that deprives moisture from the air and causes a deliquescence phenomenon, causing problems such as falling off from the dehumidifying sheet or causing rust. It is known to do. However, as in the present invention, when (a) porous silica and a hygroscopic salt are used in combination, the moisture adsorbed (b) the hygroscopic salt is efficiently retained on the surface of the (a) porous silica. Therefore, falling off and rust can be suppressed.

  The content ratio of (a) porous silica to the dehumidifying sheet of the present invention is preferably 25% by mass to 90% by mass, more preferably 35% by mass to 80% by mass, and further 40% by mass to 70% by mass. preferable. (A) When the content ratio of the porous silica is less than 25% by mass, sufficient hygroscopicity may not be obtained, and when it exceeds 90% by mass, the degree of flexibility of the dehumidifying sheet is insufficient. When processing a sheet material for dehumidification into a filter material, the sheet material may break or collapse.

  The content ratio of the (b) hygroscopic salt to the (a) porous silica of the present invention is preferably 20% by mass to 130% by mass, more preferably 30% by mass to 125% by mass, and 40% by mass to 75% by mass. Further preferred. (B) When the hygroscopic salt content is less than 20% by mass, sufficient hygroscopicity may not be obtained. On the other hand, if it exceeds 130% by mass of the preferable upper limit, the hygroscopicity of the sheet will reach its peak, dripping due to condensation may occur, and workability may deteriorate.

  The sheet material for dehumidification of the present invention preferably contains (c) organic fibers and (d) cellulosic fibrillated fibers in addition to (a) porous silica and (b) hygroscopic salt. (C) When an organic fiber is contained, a three-dimensional network space is formed and (a) porous silica is retained, or mechanical strength and extensibility are imparted to the sheet for dehumidification, thereby improving its workability. It can be improved. (D) Cellulose fibrillated fibers having a large specific surface area, finely divided, and having surface functional groups such as hydroxyl groups, include (a) excellent retention of porous silica and desorption ( It is possible to increase the suppression effect of powder omission).

  (C) Examples of organic fibers include olefin resins, polyester resins, ethylene-vinyl acetate copolymer resins, polyamide resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyvinyl ether resins, and polyvinyl ketone resins. , Polyether resin, diene resin, polyurethane resin, phenol resin, melamine resin, furan resin, urea resin, aniline resin, unsaturated polyester resin, alkyd resin, wholly aromatic polyamide resin, wholly aromatic polyester resin, wholly aromatic Polyester amide resin, wholly aromatic polyether resin, wholly aromatic polycarbonate resin, wholly aromatic polyazomethine resin, polyphenylene sulfide resin, poly-p-phenylenebenzobisthiazole resin, poly-p-phenylenebenzobisoxazole tree , Mention may be made of polybenzimidazole resin, polyether ether ketone resin, polyamideimide resin, polyimide resin, polytetrafluoroethylene resin, an organic synthetic fibers comprising a resin such as acrylics. In addition, rayon fiber that is cellulose regenerated fiber, semi-synthetic fiber such as acetate, lyocell fiber, wood pulp, cocoon, mitsumata, straw, kenaf, bamboo, linter, bagasse, esparto, sugarcane And so on.

  Among these, the plant fibers are beaten and each fiber is entangled by the action of hydrogen bonding to form a dense layer. This dense layer deteriorates air permeability, and (a) moisture to the porous silica. May be delayed or inhibited. Therefore, it is preferable to use a semi-synthetic fiber or an organic synthetic fiber as the organic fiber (c). When using vegetable fiber, it is preferable to make the content rate with respect to a sheet-like material into 20 mass% or less, 15 mass% or less is more preferable, and 10 mass% or less is further more preferable. In addition, when (b) the hygroscopic salt is contained, the dehumidification sheet-like material may become weak and the processability may be lowered. However, when the organic synthetic fiber is contained, this can be suppressed. Therefore, it is preferable.

  (C) The fiber length of the organic fiber is preferably 2 mm or more and 20 mm or less, more preferably 2 mm or more and 15 mm or less, and further preferably 3 mm or more and 10 mm or less. The content ratio of (c) organic fiber to the sheet-like material of the present invention is preferably 1% by mass to 69% by mass, more preferably 10% by mass to 62% by mass, and further preferably 22% by mass to 55% by mass. When the content ratio of the component (c) is less than 1% by mass, the (a) porous silica may not be uniformly retained in the sheet-like material. If it exceeds 69% by mass, the air permeability of the sheet may deteriorate.

In the dehumidifying sheet of the present invention, it is preferable to contain a heat-fusible organic fiber as the ( c ) organic fiber. When the heat-fusible organic fiber is contained, the mechanical strength of the sheet-like material is increased and it becomes easy to process, or (a) the detachment (powding) of the porous silica can be suppressed. In addition, the phenomenon that (b) the hygroscopic salt weakens the dehumidification sheet can be suppressed. Examples of the heat-fusible organic fibers include single fibers, and composite fibers such as core-sheath fibers (core-shell type), parallel fibers (side-by-side type), and radially divided fibers. Since the composite fiber is difficult to form a film, it does not unnecessarily cover the surface of (a) porous silica or (b) a hygroscopic salt, and while maintaining air permeability, It can prevent falling. Examples of the heat-fusible organic fibers include polypropylene short fibers, composite fibers made of polypropylene (core) and polyethylene (sheath), and composite fibers made of high-melting polyester (core) and low-melting polyester (sheath). . In addition, single fibers composed of only a low-melting resin such as polyethylene (totally melted type) can easily be formed in the sheet-like material drying step, but can be used within a range that does not impair the characteristics. The fineness of the heat-fusible organic fiber is preferably more than 0.45 dtex and not more than 2.5 dtex, more preferably not less than 0.80 dtex and not more than 2.5 dtex, and still more preferably not less than 1.0 dtex and not more than 2.5 dtex.

  In the dehumidifying sheet of the present invention, (c) the organic fiber is (c1) an organic fiber having a fineness of 0.01 dtex or more and 0.30 dtex or less, and (c2) an organic fiber having a fineness of more than 0.30 dtex but not more than 0.45 dtex. (C3) It is preferably at least two or more kinds selected from organic fibers having a fineness of more than 0.45 dtex and not more than 2.5 dtex. A three-dimensional network space formed by organic fibers having different finenesses can enhance (a) the desorption suppression effect of porous silica.

  (C1) and (c2) can improve the desorption suppression effect, and it is particularly preferable that (c1) is included. If (c1) and (c2) are included at the same time, the three-dimensional network space becomes denser and the desorption suppression effect is enhanced. (C3) can improve the formation and flexibility of the sheet material for dehumidification, and the mechanical strength and extensibility necessary for performing filter processing such as corrugating and pleating on the sheet material for dehumidification. Etc. can be remarkably improved.

  The combination of (c1) to (c3) may be any of the combination of (c1) and (c2), the combination of (c1) and (c3), and the combination of (c2) and (c3). The combination of (c1) and (c3) is more preferable from the viewpoint of the desorption suppression effect and workability. Moreover, it is particularly preferable that all of (c1), (c2) and (c3) are included.

  (D) Cellulosic fibrillated fiber is a cellulosic fiber having a whisker-like branching portion on the surface of the fiber, or a cellulosic fiber having fine fibers in which the fiber itself is very finely divided mainly in a direction parallel to the fiber axis. Means fiber. (D) It is preferable that the cellulosic fibrillated fiber has a cross-sectional diameter of at least a part of a whisker-like branch portion or divided fine fibers of 1 μm or less. The aspect ratio (fiber length (length in the longitudinal direction) / fiber diameter (cross-sectional diameter)) of the cellulosic fibrillated fiber is preferably in the range of 20 to 100,000. Moreover, it is preferable that Canadian standard freeness (JIS P8121) is 500 ml or less, and it is more preferable that it is 200 ml or less. Further, the mass average fiber length is preferably in the range of 0.1 mm to 2 mm.

(D) As a method for producing a cellulosic fibrillated fiber, for example,
(1) Cellulose material, which is a highly crystalline and highly oriented material, is prepared in the form of fibers, pulp or pellets of appropriate size, and then dispersed in water, beater, conical refiner, single disc refiner, double disc A fibrillation method using a refiner, a high-pressure homogenizer, a sand mill, or the like (see JP-A-3-174091),
(2) A method for disaggregating bacterial cellulose produced from microorganisms such as acetic acid bacteria (see JP-A-7-118303)
Can be mentioned.

  Cellulose-based materials that can be used in the method for producing a cellulose-based fibrillated fiber of (1) above include wood pulp, cocoon, mitsumata, straw, kenaf, bamboo, linter, bagasse Plant fibers such as esparto and sugarcane, rayon fibers that are cellulose regenerated fibers, semi-synthetic fibers such as acetate, lyocell fibers, fibers obtained from plant parenchyma cells, and the like. The plant parenchyma can be obtained by crushing the internal parenchyma of the stem, the mesophyll of the leaf, the fruit and the like. In addition, juice squeezed from fruit, sugar beet, sugar cane, etc. discharged from food processing factories, sugar factories and the like can be used. Fibers can be obtained by applying a pulping treatment for producing pulp from wood to plant parenchymal cells. These cellulosic materials may be used alone or in combinations of two or more.

  The content of the (d) cellulose-based fibrillated fiber in the dehumidifying sheet of the present invention is preferably 1% by mass to 15% by mass, more preferably 3% by mass to 10% by mass, and more preferably 5% by mass to 8% by mass. % Is more preferable. When the content ratio of the cellulosic fibrillated fiber is less than 1% by mass, (a) the effect of suppressing the removal (powder falling) of porous silica may be insufficient. On the other hand, if the content exceeds 15% by mass, the air permeability of the dehumidifying sheet may deteriorate, and when the dehumidifying sheet is manufactured by the papermaking method, the drainage may deteriorate, May become clogged.

  Moreover, the sheet material for dehumidification of this invention can also contain metal fibers, such as stainless steel and nickel wool, carbon fiber, a ceramic fiber, glass fiber, etc. in the range which does not impair a softness | flexibility. In addition, (a) as a water adsorbent other than porous silica, a super absorbent polymer, an organic water adsorbent such as carboxymethylcellulose, sepiolite, zeolite, bentonite, attapulgite, diatomaceous earth, activated carbon, aluminum hydroxide, allophane, imogolite Further, an inorganic moisture adsorbent such as fibrous titanium oxide may be included.

As a manufacturing method of the sheet material for dehumidification of the present invention,
(I) (a) after producing a web containing porous silica, (b) a method of supporting a hygroscopic salt,
(II) A method of supporting (a) porous silica and (b) a hygroscopic salt simultaneously or separately on a separately prepared substrate such as paper, fabric or film. As a method for producing the dehumidifying filter material of the present invention,
(III) A method of filtering the sheet material for dehumidification produced in the above (I) or (II), (IV) (a) Filtering is performed after producing a web containing only porous silica, and then (B) a method of supporting a hygroscopic salt,
(V) The method of carrying out (a) porous silica and (b) a hygroscopic salt simultaneously or separately after filtering a base material such as paper, fabric, or film prepared separately.

  In the methods (I) and (IV), as a method for producing a web containing porous silica (a), a dry method such as a card method or an air lay method, or a wet papermaking method can be used. It is preferable to use a wet papermaking method because the porous silica is uniformly dispersed. The wet papermaking method is a method in which a diluted constituent material is dispersed in water at a low concentration and then made up, and is a method that is inexpensive, highly uniform, and capable of mass production. Specifically, (a) a slurry mainly composed of porous silica and fibers is prepared, and this is filled with a filler, a dispersant, a thickener, an antifoaming agent, a paper strength enhancer, a sizing agent, a flocculant, and coloring. Add a suitable agent, fixing agent, etc., and perform wet papermaking with a paper machine. As the paper machine, a circular paper machine, a long paper machine, a short paper machine, an inclined paper machine, a combination paper machine in which the same or different kinds of paper machines are combined, and the like can be used. The web can be obtained by drying the wet paper after paper making using an air dryer, cylinder dryer, suction drum dryer, infrared dryer or the like.

  In the wet papermaking method, (a) an aggregating agent can be added to stabilize an agglomerated structure composed of porous silica and fibers. Flocculants include metal hydroxides such as zinc hydroxide, aluminum hydroxide and magnesium hydroxide, inorganic hydrated oxides such as alumina, silica, aluminum silicate and magnesium silicate, aluminum sulfate, polyaluminum chloride, anion or cation modification Polyacrylamide, polyethylene oxide polymers, water-soluble polymers such as acrylic acid or methacrylic acid-containing copolymers, alginic acid or polyvinyl phosphoric acid and their alkaline salts, alkylamines such as ammonia, diethylamine and ethylenediamine, ethanolamine, etc. There are alkanolamine, pyridine, morpholine, acryloyl-containing morpholine polymer. In particular, among the anionic or cation-modified water-soluble polymer flocculants, amphoteric flocculants having both cation units and anion units in the polymer can exhibit an excellent aggregation effect.

  In the methods (I), (II), (IV), and (V), a coating method is used as a method for supporting (a) porous silica or (b) a hygroscopic salt. As the coating liquid, a solution or dispersion containing (a) porous silica and (b) a hygroscopic salt alone or in combination is used. As the medium, water or a mixed solution of water and an organic solvent such as alcohol or ketone can be preferably used. For coating, an impregnation or coating apparatus such as a size press, a gate roll coater, an air knife coater, a blade coater, a comma coater, a bar coater, a gravure coater, a kiss coater, or a spray coater can be used.

  In the sheet for dehumidification of the present invention, when (a) porous silica and (b) hygroscopic salt are supported by the coating method, they are simultaneously supported or (a) porous silica is supported. It is preferable to support (b) a hygroscopic salt later. (B) The coating liquid containing the hygroscopic salt and water is mainly collected in the peripheral part of (a) the porous silica, and after drying, (b) the moisture absorption is selectively performed by the peripheral part of the porous silica. This is because the salt is retained.

  Examples of the substrate that can be used in the methods (II) and (V) include paper, film, porous film, woven fabric, dry nonwoven fabric, wet nonwoven fabric, and knitted fabric. These base materials may be used alone, or may be laminated and combined by bonding or the like. Among these, it is preferable from a breathable point to use porous substrates, such as paper, a porous film, a woven fabric, a dry nonwoven fabric, a wet nonwoven fabric, and a knitted fabric. In particular, the non-woven fabric has a high porosity, and even if the surface of the non-woven fabric is rubbed during filter processing, the (a) porous silica and (b) hygroscopic salt carried in the fiber matrix are not detached. A particularly suitable substrate. In addition, the coating properties and penetrability of the coating liquid can be improved by the fiber configuration.

  Examples of the resin constituting the film and porous film include olefin resin, polyester resin, polyvinyl acetate resin, ethylene vinyl acetate copolymer resin, polyamide resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl chloride. Thermoplastic synthetic resins such as ether resin, polyvinyl ketone resin, polyether resin, polyvinyl alcohol resin, diene resin, and polyurethane resin, phenol resin, melamine resin, furan resin, urea resin, aniline resin, unsaturated polyester resin, A thermosetting resin such as an alkyd resin can be used. Moreover, as a porous film, inorganic porous films, such as a punching metal sheet, a foam metal sheet, and the aggregate film of an inorganic particle, can also be used.

Dehumidification sheet of this invention has a basis weight is preferably from ^{25g / m 2 ~250g / m 2} , more preferably from ^{30g / m 2 ~200g / m 2} , 40g / m 2 ~ More preferably, it is 150 g / m ² . Moreover, 36 micrometers-415 micrometers are preferable, as for thickness, 43 micrometers-333 micrometers are more preferable, and 57 micrometers-250 micrometers are still more preferable.

The sheet material for dehumidification of the present invention may have a single layer structure or a multilayer structure. When trying to obtain a sheet-like material with a high basis weight, a multilayer structure tends to improve the formation. For example, to produce a sheet-like material having a basis weight of 100 g / m ^2, than the one-layer structure, 50 g / m 2 layer structure of ² + 50g / m ^2, 3 layers of ^{30g / m 2 + 30g / m} 2 + 40g / m 2 A structure is preferable.

  Filter processing can be performed by appropriately combining pleating processing, corrugating processing, laminating processing, roll core processing, donut processing, and the like. Lamination may be performed by laminating the dehumidifying sheet material of the present invention or laminating the dehumidifying sheet material of the present invention and paper, nonwoven fabric, woven fabric, knitted fabric, woven fabric, film, porous film, etc. May be. The substrate and the sheet for dehumidification before filtering may be improved in surface uniformity or the thickness may be adjusted by calendaring or the like.

  EXAMPLES Next, although an Example demonstrates this invention still in detail, this invention is not limited to these examples at all. In the following Examples and Comparative Examples, the parts and percentages are based on mass unless otherwise specified. In addition, Table 1 shows some of the materials used.

<Examples 1-5, 8-20>
A papermaking slurry (solid content concentration 2% by mass) was prepared at the blending ratio shown in Table 2. A flocculant (trade name: Percoll 57, Ciba Specialty Chemicals) was added to the obtained slurry in an amount of 0.2% based on the solid content, and papermaking was performed with a circular net type paper machine to a basis weight of 72 g / m ² ( a) A web containing porous silica was obtained. Furthermore, the obtained web was impregnated with an aqueous guanidine sulfamate solution (trade name: Sunflame NF-6, manufactured by San Nopco Co., Ltd.), dried at a drying temperature of 90 ° C. (b) containing a hygroscopic salt, A sheet was obtained. The concentration of the guanidine sulfamate aqueous solution was appropriately adjusted in each example so that the content ratio of (b) the hygroscopic salt to (a) porous silica was the value described in the Evaluation 2 column of Table 3. Examples 3 and 4 are reference examples.

<Example 6 (reference example) >
A papermaking slurry (solid content concentration 2% by mass) was prepared at the blending ratio shown in Table 2. A flocculant (trade name: Percoll 57, Ciba Specialty Chemicals) was added to the obtained slurry in an amount of 0.2% based on the solid content, and papermaking was performed with a circular net type paper machine to a basis weight of 72 g / m ² ( a) A web containing porous silica was obtained. Further, the obtained web was impregnated with a 5% magnesium chloride aqueous solution and dried at a drying temperature of 90 ° C. to contain (b) a hygroscopic salt to obtain a sheet.

<Example 7>
A papermaking slurry (solid content concentration 2% by mass) was prepared at the blending ratio shown in Table 2. A flocculant (trade name: Percoll 57, Ciba Specialty Chemicals) was added to the obtained slurry in an amount of 0.2% based on the solid content, and papermaking was performed with a circular net type paper machine to a basis weight of 72 g / m ² ( a) A web containing porous silica was obtained. Further, the obtained web was impregnated with an aqueous solution containing guanidine sulfamate (15%) and magnesium chloride (3%), dried at a drying temperature of 90 ° C. and (b) containing a hygroscopic salt, and a sheet-like material Got.

<Comparative Examples 1-3>
A papermaking slurry (solid content concentration 2% by mass) was prepared at the blending ratio shown in Table 2. A flocculant (trade name: Percoll 57, Ciba Specialty Chemicals) was added to the obtained slurry in an amount of 0.2% based on the solid content, and papermaking was performed with a circular net type paper machine to a basis weight of 72 g / m ² ( a) A web containing porous silica was obtained, and this was used as a sheet of the comparative example.

<Comparative example 4>
A papermaking slurry (solid content concentration 2% by mass) was prepared at the blending ratio shown in Table 2. A flocculant (trade name: Percoll 57, Ciba Specialty Chemicals) was added to the obtained slurry in an amount of 0.2% based on the solid content, and papermaking was performed with a circular net type paper machine to a basis weight of 72 g / m ² ( a) A web containing no porous silica was obtained. Further, the obtained web was impregnated with an aqueous guanidine sulfamate solution and dried at a drying temperature of 90 ° C. to obtain a sheet-like material containing only 16% of (b) a hygroscopic salt.

<Comparative Example 5>
A papermaking slurry (solid content concentration 2% by mass) was prepared at the blending ratio shown in Table 2. A flocculant (trade name: Percoll 57, Ciba Specialty Chemicals) was added to the obtained slurry in an amount of 0.2% based on the solid content, and papermaking was performed with a circular net type paper machine to a basis weight of 72 g / m ² ( a) A web containing no porous silica was obtained. Further, the obtained web was impregnated with an aqueous guanidine sulfamate solution and dried at a drying temperature of 90 ° C. to obtain a sheet-like material containing only 16% of (b) a hygroscopic salt.

<Comparative Example 6>
A papermaking slurry (solid content concentration 2% by mass) was prepared at the blending ratio shown in Table 2. A flocculant (trade name: Percoll 57, Ciba Specialty Chemicals) was added to the obtained slurry in an amount of 0.2% based on the solid content, and papermaking was performed with a circular net type paper machine to a basis weight of 72 g / m ² ( a) A web containing no porous silica was obtained. Further, the obtained web was impregnated with an aqueous magnesium chloride solution and dried at a drying temperature of 90 ° C. to obtain a sheet-like material containing only 13% of (b) a hygroscopic salt.

[Evaluation 1: (a) porous silica content ratio in web]
The webs obtained in Examples and Comparative Examples were incinerated at 600 ° C., and the content ratio [%] of the inorganic component (SiO ₂ ) in the web was determined and shown in Table 3.

[Evaluation 2: (b) Content ratio of hygroscopic salt]
(B) From the mass difference between the webs before and after the coating of the hygroscopic salt, the adhesion amount of the (b) hygroscopic salt was calculated. The content ratio [%] of (b) hygroscopic salt relative to (a) porous silica was calculated from the content of (a) porous silica determined in Evaluation 1 and the adhesion amount, and are shown in Table 3.

[Evaluation 3: Water resistance]
(B) When the hygroscopic salt was coated, the change in the web was visually observed, and the results are shown in Table 3.

[Manufacture of filter material for dehumidification]
The sheet-like materials obtained in the examples and comparative examples were processed in a single-stage corrugated process (2.0 mm step height, 4.8 mm pitch), slit into a 20 cm width, and rolled up into a cylindrical shape. A 20 cm-long dehumidifying filter material was produced.

[Evaluation 4: Workability]
Table 3 shows the processability and the presence or absence of powder falling off during the production of the filter material for dehumidification.

[Evaluation 5: Preservability]
In a variable temperature and humidity chamber adjusted to 30 ° C. and a relative humidity of 80% (absolute water content: 24.3 g), the filter material for dehumidification is left on the unexposed pulp sheet, and the unexposed pulp sheet after 48 hours has passed. Wetting was observed and the results are shown in Table 3.

A: No dripping occurred at all, and the portion where the dehumidifying filter material was left was not wet.
○: A little dripping has occurred and the part where the dehumidifying filter material is left is wet, but the area ratio is less than 45%.
(Triangle | delta): Although the dripping has generate | occur | produced and the place which left the dehumidification filter material left is wet, the area ratio is 45% or more and less than 70%.
X: A dripping occurred and the part where the dehumidifying filter material was left was wet, and the area ratio was 70% or more.

[Evaluation 6-8: Adsorption / desorption property test]
In FIG. 1, the cross-sectional schematic of the adsorption / desorption property measuring apparatus used by this evaluation is shown. A stainless steel tube 2 (inner diameter: 12 cm, length: 30 cm) is attached to the upstream side of the stainless steel tube 1 (inner diameter: 12 cm, length: 20 cm) filled with a dehumidifying filter material via an on-off valve 6. Further, on the downstream side, a stainless steel tube 3 (inner diameter: 12 cm, length: 30 cm) is attached via an on-off valve 7. Temperature and humidity meters 4 and 5 are inserted in the stainless steel pipe 2 and the stainless steel pipe 3 respectively, so that the temperature and humidity of air (upstream side) and air (downstream side) can be measured.

1. Initial dry state adjustment First, the moisture absorption / release measurement device is placed in a variable temperature and humidity chamber adjusted to 25 ° C. and a relative humidity of 60% (absolute water content: 13.8 g). Open the on-off valves 6 and 7, and let the heated air adjusted to 45 ° C from the stainless steel pipe 2 flow in so that the downstream side air flow becomes 2m / sec, and adjust the dehumidifying filter material to the initial dry state. To do.

2. Adsorption test Thereafter, the inflow of heated air is stopped, the on-off valves 6 and 7 are closed, and left for 30 minutes, and the temperature of the dehumidifying filter material is lowered to 25 ° C. Subsequently, the on-off valves 6 and 7 were opened, and air at 25 ° C. and a relative humidity of 60% was introduced from the stainless tube 2 so that the downstream side air volume was 2 m / sec. Record temperature and humidity for 6 minutes. The amount of adsorbed moisture is calculated from the absolute humidity fluctuation amount from the average value of the absolute humidity for 30 seconds immediately before opening the on-off valves 6 and 7, and the fluctuating moisture for 15 seconds and 75 seconds immediately after opening the on-off valves 6 and 7 The amounts were integrated to obtain a 15-second adsorption amount (first time) and a 75-second adsorption amount (first time), respectively.

3. Next, the inflow of air is once stopped, and the on-off valves 6 and 7 are closed. The on-off valves 6 and 7 are opened again, and heated air adjusted to 45 ° C. at 25 ° C. and 60% relative humidity is introduced from the stainless tube 2 so that the downstream side air flow becomes 2 m / sec. Record the temperature and humidity measured with hygrometer 5 for 6 minutes. The amount of moisture released is calculated from the absolute humidity fluctuation amount from the average value of the absolute humidity for 30 seconds immediately before opening the on-off valves 6 and 7, and the fluctuation water amount for 75 seconds immediately after opening the on-off valves 6 and 7 is calculated. The total amount was taken as the 75-second desorption amount (first time).

  Steps 2 and 3 were repeated twice, and a 15-second adsorption amount (second and third times), a 75-second adsorption amount (second and third times), and a 75-second desorption amount (second and third times) were measured. Table 4 shows the 15-second adsorption amount as evaluation 6, the 75-second adsorption amount as evaluation 7, and the 75-second desorption amount as evaluation 8. The unit is g. In addition, 75 seconds is the time required for the adsorption zone and the regeneration zone in an example of a desiccant air conditioner that has been put into practical use.

  (A) 15-second adsorption amount (Evaluation 6) of the sheet-like materials of Examples 1 to 7 and Comparative Example 1 in which (a-1) was used as the porous silica and the web was produced using the same papermaking slurry. (B) In Examples 1 to 7 containing a hygroscopic salt, (a) the porous silica is moistened by (a) the hygroscopic salt adhering to the porous silica. The phenomenon of delaying the start of adsorption was observed, and the 15-second adsorption amount of Comparative Example 1 in which the porous silica in the bare state (a) adsorbs moisture was larger. However, when comparing the 75-second adsorption amount (Evaluation 7), in comparison with Comparative Example 1 in which the desorption of moisture due to heat of adsorption starts and the adsorption amount does not increase, Examples 1-7 show a high 75-second adsorption amount. Was confirmed. Therefore, in an actual desiccant air conditioner, the sheet-like material of Examples 1 to 7 can obtain dehumidified air more efficiently than the sheet-like material of Comparative Example 1 while the dehumidification rotor passes through the adsorption zone. . Further, during the recording time of 6 minutes, the adsorption amount of Comparative Example 1 was almost saturated at the adsorption amount of 75 seconds, but the adsorption amounts of Examples 1 to 7 continued to rise further.

  (B) The 75-second desorption amount (Evaluation 8) of Examples 1 to 7 containing a hygroscopic salt was slightly less than the 75-second adsorption amount or more than the 75-second adsorption amount. On the other hand, in Comparative Example 1, it was confirmed that only moisture less than the adsorbed amount for 75 seconds could be desorbed. Therefore, in the sheet-like material of Comparative Example 1, in the actual desiccant air conditioner, while the dehumidification rotor passes through the regeneration zone, the moisture adsorbed in the adsorption zone cannot be completely released, and the dehumidification performance gradually decreases. However, since the sheet-like materials of Examples 1 to 7 can be fully released, the initial dehumidifying performance can be maintained.

  Further, (a) Comparison between Example 17 using (a-2) as porous silica and Comparative Example 2 and comparison between Example 19 and Comparative Example 3 using (a-3) were evaluated as 6 -8 showed the above-mentioned tendency, and it was confirmed that dehumidified air can be obtained efficiently in the sheet-like material of the example.

  (B) In the sheet-like material of Comparative Examples 4 to 6 containing hygroscopic salt but not containing (a) porous silica, the adsorbed amount and the desorbed amount were very small (evaluation 6 to 8). ). In Evaluation 5, dripping occurred, and 70% or more of the portion where the dehumidifying filter material was left was wet. In Examples 1 to 20 in which (a) porous silica and (b) a hygroscopic salt were used in combination, it was difficult for dripping to occur as compared with Comparative Examples 4 to 6.

  When Examples 1 to 5 are compared, it is confirmed that (a) when the content ratio of guanidine sulfamate with respect to porous silica increases, the 75-second adsorption amount (Evaluation 7) and the 75-second desorption amount (Evaluation 8) increase. It was. (A) In Example 4 in which the content ratio of (b-1) to the porous silica was less than 20%, the 75-second desorption amount might be slightly smaller than the 75-second adsorption amount. Further, in Example 3 in which the content of (b-1) with respect to (a) porous silica exceeds 130%, in evaluation 5, dripping occurred and 45% of the places where the dehumidifying filter material was left untreated. Less than wet. (A) In Examples 1, 2, and 5 in which the content ratio of (b-1) to the porous silica is 20 to 130%, a 75-second desorption amount larger than the 75-second adsorption amount was obtained, and no dripping occurred at all. There wasn't.

  In Examples 1 and 8 to 16, the blending ratio of (a) porous silica in the papermaking slurry is equal, and other fiber blending ratios are changed. Among these, (d) in Example 13 which does not contain cellulosic fibrillated fibers, (a) porous silica is largely removed during paper making, and the content of (a) porous silica in the web is low. (Evaluation 1), 75 second adsorption amount (evaluation 7) and 75 second desorption amount (evaluation 8) tended to be small.

  Since Example 11 does not contain heat-fusible fiber as (c) organic fiber, paper breakage may occur during coating of (b) hygroscopic salt (Evaluation 3). Moreover, when manufacturing the filter material for dehumidification, the powder fall-off from the cut surface was also confirmed (evaluation 4).

  (C) Example 10 containing (c3) organic fiber having a fineness of more than 0.45 dtex and not more than 2.5 dtex and pulp that is vegetable fiber as the organic fiber is (a) porous in the web Despite the silica content of 48%, there was a tendency for the amount of adsorption and desorption to be smaller than those of Examples 1, 9, 11, 12, 14 to 16 (Evaluation 6 to 8). . This is probably because (a) moisture adsorption on the porous silica is suppressed by the dense layer composed of the hydrogen bonds of the pulp. Also in the comparison with Examples 17 and 18 and the comparison with Examples 19 and 20, in Examples 18 and 20 containing pulp fibers, there was a tendency that the adsorption amount and the desorption amount were small.

  (C) As organic fibers, (c1) organic fibers having a fineness of 0.01 dtex or more and 0.30 dtex or less, (c2) organic fibers having a fineness of more than 0.30 dtex but not more than 0.45 dtex, (c3) exceeding a fineness of 0.45 dtex Examples 1, 8, 9, 11 containing any two or more compared to Examples 14 to 16 containing only any one of the organic fibers of 2.5 dtex or less In No. 12, (a) porous silica was not easily dropped during paper making, and the (a) porous silica content in the web was high. The content ratio of Example 1 containing three kinds was the best.

  Examples (1), (8), (9), (11) compared with Examples (12), (15) and (16) which do not contain (c) organic fibers of (c3) fineness exceeding 0.45 dtex and not more than 2.5 dtex. , 14 was excellent in the flexibility of the sheet-like material, and was easy to process into a filter material. In addition, (c) organic fiber (c1) organic fiber having a fineness of 0.01 dtex or more and 0.30 dtex or less, (c2) organic fiber having a fineness of more than 0.30 dtex but not more than 0.45 dtex, c3) fineness of 0.45 dtex In Examples 14-16 which contain only any 1 type among the organic fiber of 2.5 dtex or less exceeding, Example 15 and 16 are (a) drop-off | omission of the porous silica at the time of papermaking is suppressed. It was.

  In addition to being used as a dehumidifying filter material, the sheet-like material of the present invention can be used as a packaging material, a dehumidifying sheet for indentation and chase, interior materials such as wallpaper and flooring. Moreover, the filter material for dehumidification of this invention can be used as a humidity control element or a heat exchange element, for example. Specific examples of humidity control elements and heat exchange elements include dehumidification rotors, building air-conditioning vaporization type humidification elements, fuel cell humidification elements, dehumidifier dehumidification elements, water absorption transpiration elements such as vending machines, water absorption transpiration elements for cooling, A dehumidifying rotor of a desiccant air conditioner, a total heat exchange element, etc. can be mentioned.

It is the cross-sectional schematic of the moisture absorption / release measurement apparatus used in the Example of this invention.

Explanation of symbols

1 Stainless steel pipe filled with filter material for dehumidification 2 Stainless steel pipe (upstream side)
3 Stainless steel pipe (downstream)
4 Thermo-hygrometer (upstream side)
5 Thermo-hygrometer (downstream side )
6 On-off valve (upstream side)
7 On-off valve (downstream)

Claims (5)

(A) porous silica, Ri Na contain at least (b) hygroscopic salt, (a) content of to the porous silica (b) hygroscopic salt is 20 to 130 wt%, (b) moisture dehumidification sheet that uses a guanidine salt as sexual salt. Furthermore, the sheet-like material for dehumidification of Claim 1 formed by containing (c) organic fiber and (d) cellulosic fibrillated fiber. (C) The sheet-like material for dehumidification according to claim 2, comprising at least a heat-fusible organic fiber as the organic fiber. (C) As organic fibers, (c1) organic fibers having a fineness of 0.01 dtex or more and 0.30 dtex or less, (c2) organic fibers having a fineness of more than 0.30 dtex but not more than 0.45 dtex, (c3) exceeding a fineness of 0.45 dtex The sheet material for dehumidification according to claim 2, comprising at least two kinds selected from organic fibers of 2.5 dtex or less. A filter material for dehumidification comprising the sheet material for dehumidification according to claim 1.

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