JP2020172034A - Water-absorbing vaporized material - Google Patents

Abstract

To provide a water-absorbing vaporized material that is excellent in a water-absorbing property, a vaporization property, and rigidity.SOLUTION: A water-absorbing vaporized material includes a three-layer structure in which nonwoven fabrics including ultrafine fibers with a fiber diameter of 10 to 1500 nm are laminated on both surfaces of a nonwoven fabric base material and the Gurley type bending stiffness of the nonwoven fabric base material is higher than that of the nonwoven fabric layers including the ultrafine fibers. It is preferable that the water-absorbing property of the three-layer structure is 5 cm or more in accordance with the Byreck method. It is also preferable that the drying rate of the three-layer structure, which is wetted with water, measured on a heat transfer plate at a temperature of 30°C is 0.040 g/h/cm2 or more.SELECTED DRAWING: None

Description

The present invention relates to a water-absorbing vaporizing material having excellent water absorption and vaporization properties and excellent rigidity.

In recent years, there is a problem that the inside of a building becomes dry due to the development of air-conditioning equipment and the like of a building and the airtightness of the building, and a humidifier is often used. There are three main types of humidifiers. There are two types: a steam type that heats and evaporates water to generate steam, an ultrasonic type that blows water into a mist using ultrasonic waves, and a vaporization type that blows air on a water-absorbing vaporizing material that contains water to evaporate it. The steam type has a high humidifying capacity, but has the disadvantage of using a large amount of electricity, making it unsuitable for large buildings. The ultrasonic type is characterized by fine water vapor particles, high humidification capacity, and low power consumption, but it is not suitable for large buildings that operate automatically for 24 hours because all dirty water is converted to water vapor. .. The vaporization type consumes less power and evaporates only water vapor, so there is no risk of bacteria spreading inside the building. Among them, there is a dropping method as a humidifying method having a high humidifying capacity and suitable for long-term use.

Conventionally, a hydrophilic water-absorbing vaporizing material has been used as a vaporizing-type water-absorbing vaporizing material for a humidifier (for example, Patent Document 1). In such a water-absorbing vaporizing material, since processability (pleats forming property, etc.) is required and the water-absorbing vaporizing material needs vaporization to evaporate water after absorbing water, cellulose is retained because it retains water. Not suitable. In order to solve this, a method of using a hydrophilic polymer component (acrylic resin or styrene-acrylic copolymer) for polyester fiber and a method of water-absorbing a water-absorbing vaporizing material have been proposed (for example, patent documents). 2. Patent Document 3). However, these methods have problems that the water absorption due to aged deterioration of the water absorption process is lowered, and the water absorption vaporizing material formed only of these materials has weak rigidity and insufficient morphological stability.

Japanese Unexamined Patent Publication No. 2004-250838 Japanese Unexamined Patent Publication No. 2011-196601 JP-A-2009-225785

The present invention has been made in view of the above background, and an object of the present invention is a water-absorbing vaporizing material having excellent water absorption and vaporization properties and excellent rigidity.

As a result of diligent studies to achieve the above problems, the present inventor has excellent water absorption and vaporization properties and excellent rigidity by skillfully devising the fiber diameter and layer structure of the fibers constituting the water absorption vaporization material. The present invention was completed by finding a vaporizing material and conducting further diligent studies.

Thus, according to the present invention, "a non-woven fabric containing ultrafine fibers having a fiber diameter of 10 to 1500 nm is laminated on both surfaces of the non-woven fabric base material, and the non-woven fabric having a galley stiffness of the non-woven fabric base material containing the ultrafine fibers is laminated. A water-absorbing and vaporizing material, characterized in that it consists of a three-layer structure higher than the layer of. "
At that time, it is preferable that the water absorption of the three-layer structure by the Bilek method is 5 cm or more. Further, it is preferable that the drying rate measured on a heat transfer plate at 30 ° C. by moistening the three-layer structure with water is 0.040 g / h / cm ² or more.
Further, it is preferable that the ultrafine fiber is any fiber selected from the group consisting of polyester fiber, polyphenylene sulfide fiber, polyolefin fiber, and nylon fiber.
Further, in the nonwoven fabric containing the ultrafine fibers, the content of the ultrafine fibers is preferably 5% by mass or more with respect to the mass of the nonwoven fabric. On the other hand, the content of ultrafine fibers in the non-woven fabric is preferably 60% by mass or less. In the case of a non-woven fabric made of ultrafine fibers alone (100% by mass), the porosity becomes too small, and rather tends to develop water repellency, making it difficult to achieve the water absorption required for the present invention. By including the ultrafine fibers, a non-woven fabric having a high porosity structure with a fine porosity size can be produced, thereby achieving a water-absorbing vaporizing material having good water absorption and humidification (here, drying rate). be able to.
Further, the non-woven fabric containing ultrafine fibers is preferably a wet non-woven fabric. Further, it is preferable that the nonwoven fabric base material is a spunbonded nonwoven fabric or a thermal bonded nonwoven fabric. Further, the water-absorbing vaporizing material of the present invention is suitably used as a water-absorbing vaporizing material for a vaporization type humidifier.

According to the present invention, a water-absorbing vaporizing material having excellent water absorption and vaporization properties and excellent rigidity can be obtained.

Hereinafter, embodiments of the present invention will be described in detail. The water-absorbent vaporizing material of the present invention is formed by laminating a non-woven fabric containing ultrafine fibers having a fiber diameter of 10 to 1500 nm on both surfaces of the non-woven fabric base material, and the non-woven fabric having a galley rigidity of the non-woven fabric base material containing the ultrafine fibers is laminated. Consists of a three-layer structure higher than the layer of. That is, in the water-absorbing vaporizing material of the present invention, a non-woven fabric containing ultrafine fibers having a fiber diameter of 10 to 1500 nm, a non-woven fabric base material, and a non-woven fabric containing ultrafine fibers having a fiber diameter of 10 to 1500 nm are laminated in this order, and at least 3 Has a layer.
Here, if the fiber diameter is larger than 1500 nm, the capillary phenomenon does not work sufficiently, and the water absorption may decrease. On the contrary, if the fiber diameter is smaller than 10 nm, production may become difficult.

Here, the fiber diameter can be measured by taking a cross-sectional photograph of a single fiber at a magnification of 30,000 times with a transmission electron microscope TEM. At that time, in the TEM having a length measuring function, the length measuring function can be utilized for measurement. Further, in a TEM having no length measuring function, the photograph taken may be enlarged and copied, and the measurement may be performed with a ruler after considering the scale. When the cross-sectional shape of the single fiber is a modified cross section other than the round cross section, the diameter of the circumscribed circle of the cross section of the single fiber shall be used as the fiber diameter.
In the ultrafine fibers, the aspect ratio (ratio L / D of the fiber length L to the fiber diameter D) is preferably in the range of 100 to 2500.

As the fiber type of the ultrafine fiber, polyester fiber, polyphenylene sulfide (PPS) fiber, polyolefin fiber or nylon (Ny) fiber is preferable. Examples of the polyester forming the polyester fiber include polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), and polyethylene naphthalate, and these are the main repeating units, and isophthalic acid is used as another copolymer component. Aromatic dicarboxylic acids such as 5-sulfoisophthalic acid metal salts, aliphatic dicarboxylic acids such as adipic acid and sebacic acid, hydroxycarboxylic acid condensates such as ε-caprolactone, diethylene glycol, trimethylene glycol, tetramethylene glycol and hexamethylene. A copolymer obtained by further copolymerizing a glycol component such as glycol is preferable. It may be a material-recycled or chemically-recycled polyester, or polyethylene terephthalate using a monomer component obtained from biomass, that is, a substance derived from a living material, which is described in JP-A-2009-0916994. Further, a polyester obtained by using a catalyst containing a specific phosphorus compound and titanium compound as described in JP-A-2004-27097 and JP-A-2004-21268 may be used.

As the polyarylene sulfide resin forming the polyphenylene sulfide (PPS) fiber, any polyarylene sulfide resin may be used as long as it belongs to the category called polyarylene sulfide resin. The polyarylene sulfide resin has, as its constituent units, for example, p-phenylene sulfide unit, m-phenylene sulfide unit, o-phenylene sulfide unit, phenylene sulfide sulfone unit, phenylene sulfide ketone unit, phenylene sulfide ether unit, diphenylene sulfide unit. , Phenylene sulfide unit containing a substituent, phenylene sulfide unit containing a branched structure, and the like. Among them, those containing 70 mol% or more, particularly 90 mol% or more of p-phenylene sulfide units are preferable, and poly (p-phenylene sulfide) is more preferable.

Further, the polyolefin fiber includes polypropylene fiber and polyethylene fiber. The nylon fibers include nylon 6 fibers and nylon 66 fibers.
The method for producing the ultrafine fibers is not particularly limited, but the method disclosed in International Publication No. 2005/095686 pamphlet is preferable. That is, in terms of fiber diameter and its uniformity, an island component composed of a fiber-forming thermoplastic polymer and a polymer that is more soluble in an alkaline aqueous solution than the above-mentioned fiber-forming thermoplastic polymer (hereinafter, "easily soluble"). It is preferable that the composite fiber having a sea component composed of "polymer") is subjected to an alkali weight loss process to dissolve and remove the sea component.

Here, when the dissolution rate ratio of the alkaline aqueous solution easily soluble polymer forming the sea component to the fiber-forming thermoplastic polymer forming the island component is 200 or more (preferably 300 to 3000), the island separability is good. It is preferable. When the dissolution rate is less than 200 times, the island component in the surface layer of the separated fiber section is dissolved while the sea component in the center of the fiber section is dissolved, so that the sea component is dissolved due to the small fiber diameter. Despite the weight loss, the sea component in the center of the fiber cross section cannot be completely dissolved and removed, leading to thickness unevenness of the island component and solvent erosion of the island component itself, and fibers with a uniform fiber diameter cannot be obtained. There is a risk.

As the easily soluble polymer forming the sea component, polyesters having particularly good fiber forming properties, aliphatic polyamides, and polyolefins such as polyethylene and polystyrene can be mentioned as preferable examples. Further, to give a specific example, polylactic acid, an ultrahigh molecular weight polyalkylene oxide condensation polymer, and a copolymerized polyester of a polyalkylene glycol compound and 5-sodium sulfoisophthalic acid are preferable because they are easily dissolved in an alkaline aqueous solution. Here, the alkaline aqueous solution means potassium hydroxide, sodium hydroxide aqueous solution, or the like. In addition to this, as a combination of the sea component and the solution for dissolving the sea component, hydrocarbons for aliphatic polyamides such as nylon 6 and nylon 66, trichloroethylene for polystyrene and polyethylene (particularly high pressure method low density polyethylene and straight chain) Examples include hydrocarbon solvents such as hot toluene and xylene for low-density polyethylene, and hot water for polyvinyl alcohol and ethylene-modified vinyl alcohol-based polymers.

Among polyester polymers, polyethylene terephthalate having an intrinsic viscosity of 0.4 to 0.6 obtained by copolymerizing 6 to 12 mol% of 5-sodium sulfoisophthalic acid and polyethylene glycol having a molecular weight of 4000 to 12000 by 3 to 10% by mass. Polymerized polyester is preferred. Here, 5-sodium sulfoisophthalic acid contributes to the improvement of hydrophilicity and melt viscosity, and polyethylene glycol (PEG) improves the hydrophilicity. In addition, the larger the molecular weight of PEG, the more hydrophilicity it is thought to be due to its higher-order structure, but the reactivity deteriorates and it becomes a blend system, which causes problems in terms of heat resistance and spinning stability. there is a possibility. Further, when the copolymerization amount is 10% by mass or more, the melt viscosity may decrease.

On the other hand, as the poorly soluble polymer forming the island component, polyamides, polyesters, polyphenylene sulfides, polyolefins and the like are preferable examples. Specifically, in applications that require mechanical strength and heat resistance, polyesters include polyethylene terephthalate (PET), polytrimethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and isophthalate having these as the main repeating units. Aromatic dicarboxylic acids such as acids and 5-sulfoisophthalic acid metal salts, aliphatic dicarboxylic acids such as adipic acid and sebacic acid, hydroxycarboxylic acid condensates such as ε-caprolactone, diethylene glycol, trimethylene glycol, tetramethylene glycol and hexa A copolymer with a glycol component such as methylene glycol is preferable. Further, as the polyamides, aliphatic polyamides such as nylon 6 (Ny-6) and nylon 66 (Ny-66) are preferable. In addition, polyolefins are not easily attacked by acids and alkalis, and because of their relatively low melting point, they can be used as binder components after being taken out as ultrafine fibers. High-density polyethylene, medium-density polyethylene, high-pressure method Preferred examples include low-density polyethylene, linear low-density polyethylene, isotactic polypropylene, ethylene-propylene copolymer, and ethylene copolymer of vinyl monomer such as maleic anhydride. In particular, polyesters such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate isophthalate having an isophthalic acid copolymerization rate of 20 mol% or less, polyethylene naphthalate, or aliphatic polyamides such as nylon 6 and nylon 66. Is preferable because it has heat resistance and mechanical properties due to its high melting point, and can be applied to applications requiring heat resistance and strength as compared with ultrafine fibrillated fibers made of polyvinyl alcohol / polyacrylonitrile mixed spinning fibers. The island component is not limited to a round cross section, but may be a modified cross section such as a triangular cross section or a flat cross section.

As for the polymer forming the sea component and the polymer forming the island component, a matting agent, an organic filler, and an antioxidant are required as long as they do not affect the yarn-forming property and the physical properties of the main fiber after extraction. Agents, heat stabilizers, light stabilizers, flame retardants, lubricants, antistatic agents, rust preventives, cross-linking agents, foaming agents, fluorescent agents, surface smoothing agents, surface gloss improvers, mold release improvers such as fluororesins, It does not matter if it contains various additives such as.
In the sea-island type composite fiber, it is preferable that the melt viscosity of the sea component at the time of melt spinning is larger than the melt viscosity of the island component polymer. In such a relationship, even if the composite mass ratio of the sea component is as small as less than 40%, the islands are bonded to each other or most of the island components are bonded to be different from the sea-island type composite fiber. hard.

The preferred melt viscosity ratio (sea / island) is in the range of 1.1 to 2.0, especially 1.3 to 1.5. If this ratio is less than 1.1 times, the island components are joined during melt spinning. On the other hand, if it exceeds 2.0 times, the viscosity difference is too large and the spinning tone tends to decrease.
Next, the number of islands is preferably 100 or more (more preferably 300 to 1000). The sea-island composite mass ratio (sea: island) is preferably in the range of 20:80 to 80:20. Within such a range, the thickness of the sea component between the islands can be reduced, the dissolution and removal of the sea component becomes easy, and the conversion of the island component into ultrafine fibers becomes easy, which is preferable. Here, when the ratio of the sea component exceeds 80% by mass, the thickness of the sea component becomes too thick, while when it is less than 20% by mass, the amount of the sea component becomes too small and bonding occurs between the islands. It will be easier.

As the mouthpiece used for melt spinning, any one having a hollow pin group or a micropore group for forming an island component can be used. For example, even with a spinneret, a cross section of a sea island is formed by merging an island component extruded from a hollow pin or a micropore and a sea component flow whose flow path is designed to fill the space between them and compressing this. Good. The discharged sea-island type composite fiber is solidified by cooling air and is taken up by a rotating roller or ejector set to a predetermined take-up speed to obtain an undrawn yarn. The pick-up speed is not particularly limited, but is preferably 200 to 5000 m / min. At 200 m / min or less, productivity may deteriorate. Further, if the speed is 5000 m / min or more, the spinning stability may deteriorate.
The obtained fiber may be directly used in the cutting step or the subsequent extraction step depending on the use and purpose of the ultrafine fiber obtained after extracting the sea component, or may have the desired strength, elongation and heat shrinkage characteristics. In order to match, it can be subjected to a cutting step or a subsequent extraction step via a stretching step or a heat treatment step. The drawing step may be a separate stretching method in which spinning and stretching are performed in separate steps, or a straight stretching method in which spinning is performed immediately after spinning in one step may be used.

Next, the composite fiber is cut so that the ratio L / D of the fiber length L to the island diameter D is in the range of 100 to 2500. It is preferable that such a cut is made into a toe bundled in units of tens to millions and cut with a guillotine cutter, a rotary cutter or the like.
The fiber having the fiber diameter D is obtained by subjecting the composite fiber to an alkali weight loss process. At that time, in the alkali weight loss processing, the ratio (bath ratio) of the fiber to the alkaline solution is preferably 0.1 to 5%, more preferably 0.4 to 3%. If it is less than 0.1%, there is a lot of contact between the fiber and the alkaline solution, but there is a risk that processability such as drainage will be difficult. On the other hand, if the amount is 5% or more, the amount of fibers is too large, so that the fibers may be entangled with each other during the alkali weight loss processing. The bath ratio is defined by the following formula.
Bath ratio (%) = (fiber mass (gr) / alkaline aqueous solution mass (gr) x 100)

Further, the treatment time for the alkali weight loss processing is preferably 5 to 60 minutes. If it is less than 5 minutes, the alkali weight loss may be insufficient. On the other hand, if it exceeds 60 minutes, even the island component may be reduced.
Further, in the alkali weight loss processing, the alkali concentration is preferably 2 to 10% by mass. If it is less than 2% by mass, the alkali may be insufficient and the weight loss rate may become extremely slow. On the other hand, if it exceeds 10% by mass, the alkali weight loss progresses too much, and the weight may be reduced to the island part.
The order of the cutting step and the alkali weight loss step may be reversed, and the alkali weight loss processing may be performed first, and then the cutting may be performed.

In the non-woven fabric containing the ultrafine fibers, the non-woven fabric may be composed of only the above-mentioned ultrafine fibers, but it is preferable to use the binder fibers together.
As the binder fiber, undrawn fibers (birefringence (Δn) of 0.05 or less) or composite fibers having a single fiber fineness of 0.1 dtex (fiber diameter 3 μm) or more can be used.
Here, in the binder fiber composed of undrawn fibers and composite fibers, the single fiber fineness is preferably 0.2 to 3.3 dtex (more preferably 0.5 to 1.7 dtex). The fiber length of the binder fiber B is preferably 1 to 20 mm (more preferably 3 to 10 mm). When a binder fiber made of undrawn fibers is used, a thermocompression bonding step is required after the paper making process, and therefore it is preferable to perform a calendar / embossing process after the paper making process.

Among the above binder fibers, examples of the undrawn fibers include undrawn polyester fibers spun at a spinning speed of preferably 800 to 1200 m / min, more preferably 900 to 1150 m / min. Here, examples of the polyester used for the unstretched fiber include polyethylene terephthalate, polytrimethylene terephthalate, and polybutylene terephthalate, and polyethylene terephthalate and polytrimethylene terephthalate are preferable for reasons such as productivity and dispersibility in water. Is preferable.

On the other hand, among the binder fibers, as the composite fiber, a polymer component (for example, amorphous copolymer polyester) that is fused by heat treatment at 80 to 170 ° C. after papermaking and exhibits an adhesive effect is arranged in the sheath portion, and these are arranged. A core-sheath type composite fiber in which another polymer having a melting point of 20 ° C. or higher (for example, ordinary polyester such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate) is arranged in the core portion is preferable. The binder fiber B is known as a core-sheath type composite fiber, an eccentric core-sheath type composite fiber, a side-by-side type composite fiber, etc., in which the binder component (low melting point component) forms all or part of the surface of the single fiber. Binder fiber may be used.

Here, the above-mentioned amorphous copolymer polyester is terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, adipic acid, sebacic acid, azelaic acid, dodecanoic acid, 1,4-cyclohexane. Acid components such as dicarboxylic acid, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, 1,4-cyclohexanediol, 1, It is obtained as a random or block copolymer with a diol component such as 4-cyclohexanedimethanol. Above all, it is preferable to use terephthalic acid, isophthalic acid, ethylene glycol and diethylene glycol, which have been widely used in the past, as main components in terms of cost. Such a copolymerized polyester has a glass transition point in the range of 50 to 100 ° C. and does not show a clear crystal melting point.

In the water-absorbing vaporizing material of the present invention, as fibers other than the above-mentioned ultrafine fibers and binder fibers, various synthetic fibers (polyethylene terephthalate, polytrimethylene terephthalate, nylon, olefin type, aramid type), natural pulp such as wood pulp and linter pulp , Synthetic pulp containing aramid or polyethylene as a main component can be used. In particular, polyethylene terephthalate short fibers made of stretched polyethylene terephthalate having a single fiber fineness of 0.05 to 0.6 dtex and a fiber length of 3 to 10 mm are preferable from the viewpoint of dimensional stability and the like.

The non-woven fabric containing the ultrafine fibers is preferably made of a wet non-woven fabric. As a method for producing such a wet non-woven fabric, a normal long net paper machine, a short net paper machine, a round net paper machine, or a production method in which a plurality of these are combined to make a multi-layer paper machine and then heat-treated is preferable. At that time, as the heat treatment step, either a Yankee dryer or an air-through dryer can be used after the papermaking process. Further, after the heat treatment, a calendar / embossing of a metal / metal roller, a metal / paper roller, a metal / elastic roller or the like may be performed.
Here, in the ultrafine fiber non-woven fabric layer (layer of the non-woven fabric containing ultrafine fibers), the content of the ultrafine fibers is preferably 5% by mass or more (more preferably 20 to 50% by mass) with respect to the layer mass.

In the water-absorbing and vaporizing material of the present invention, the non-woven fabric base material is preferably a spunbonded non-woven fabric or a thermal-bonded non-woven fabric. Further, it is preferable that the non-woven fabric base material has higher galley rigidity and softness (more preferably 1000 to 5000 mfg) than the ultrafine fiber non-woven fabric. If the Gale rigidity and softness is less than 1000 mfg, the rigidity may become too weak. Further, if the Gale rigidity and softness exceeds 5000 mfg, the rigidity may become too high.
As a method for producing a water-absorbent vaporizing material having a multi-layer structure as described above, for example, after obtaining the wet non-woven fabric as described above, it is bonded to a non-woven fabric base material made of various spunbonds or thermal bonds using a laminating machine or the like. It is good.

In the water-absorbing vaporizing material thus obtained, the basis weight is preferably in the range of ²⁰ to 500 g / m ² (more preferably 35 to 500 g / m ² , particularly preferably 50 to 300 g / m ² ). If the basis weight is less than 20 g / m ² , the strength may become too weak. Further, if the basis weight exceeds 500 g / m ² , the rigidity may become too high.
Here, in the water-absorbing vaporizing material, the drying rate on the heat transfer plate at 30 ° C. after wetting with water is preferably 0.040 g / h / cm ² or more. If the drying rate is less than 0.040 g / h / cm ² , the vaporization property may become too low.

Since the water-absorbent vaporizing material of the present invention has ultrafine fibrous non-woven fabric layers on both surfaces of the non-woven fabric base material, it is excellent in water absorption and vaporization. Moreover, since it has a non-woven fabric base material at the center, it has excellent rigidity. In particular, because it has excellent rigidity, it also has excellent independence. Then, since it is possible to prevent contact with the adjacent sheet due to sagging during use, it is suitably used as a water-absorbing vaporizing material for a vaporization type humidifier.

(1) Fiber diameter A transmission cross-sectional photograph was taken and measured at a magnification of 30,000 times using a transmission electron microscope TEM (with a length measuring function). However, as the fiber diameter, the diameter of the circumscribed circle in the cross section of the single fiber was used (mean value of n number 5).
(2) Fiber length Using a scanning electron microscope (SEM), the ultrafine short fibers (short fibers A) before dissolution and removal of sea components were laid on the substrate, and the fiber length L was measured at a magnification of 20 to 500 (n). Average value of number 5). At that time, the fiber length L was measured by utilizing the length measuring function of the SEM.
(3) Metsuke The basis weight was measured based on JIS P8124 (method for measuring metric basis weight of paper).
(4) Thickness The thickness was measured based on JIS P8118 (method for measuring the thickness and density of paper and paperboard). The measured load was 75 g / cm ² and n = 5, and the average value was calculated.
(5) Porosity The porosity was calculated from the basis weight, thickness, and fiber density (g / cm ³ ) by the following formula.
Porosity (%) = 100-((Metsuke) / (Thickness) / Fiber density x 100)
(6) Bilek Water Absorption Performed based on JIS L1907 (water absorption test method for textile products).
(7) Vaporization (drying rate)
Evaluation was performed with Thermolab II (manufacturer: Kato Tech Co., Ltd.) (hot plate 30 ° C.) in a test environment of 20 ° C. × 65% RH.
The initial mass of a 10 cm square sample was measured, the mass after being sufficiently immersed in water was measured, and the amount of water held (g) was calculated.
The sample measured above was placed on a hot plate, the transition of power consumption was measured, and the time until the power consumption became 2 W or less was defined as the drying time (sec).
The drying rate (g / h / cm ² ) was calculated from the sample area, water holding amount, and drying time by the following formula.
Drying speed = Water discharge amount / Drying time / Sample area (8) Rigidity (Gale rigidity / softness)
Gale stiffness and softness were measured based on JIS L1085 (nonwoven interlining test method). The stiffness of 2000 mgf or more was evaluated as "◯", and the hardness of less than 2000 mgf was evaluated as "x" on a two-point scale.

[Example 1]
Using polyethylene terephthalate (PET) as the island component and polyethylene terephthalate copolymerized with 5-sodium sulfoisophthalic acid as the sea component, after spinning and stretching, it was cut with a guillotine cutter. Sea: island = 30:70, number of islands 836, A sea-island type composite fiber having a fineness of 5.6 dtex and a cut length of 0.5 mm was obtained. This was reduced by 30% at 50 ° C. with a 3.5% NaOH aqueous solution to obtain the present fiber as ultrafine fiber 1 (stretched polyester fiber, fiber diameter 400 nm, fiber length 0.5 mm). Next, unstretched polyethylene terephthalate fiber obtained by spinning polyethylene terephthalate fiber having a fineness of 0.1 dtex × fiber length of 3 mm and polyethylene terephthalate as a binder fiber by a conventional method (single fiber fineness 1.7 dtex, fiber length 5.0 mm). Was prepared, mixed at a mass ratio of 20:70:10, wet-made paper was made with a paper machine, and dried at 120 ° C. with a Yankee dryer to obtain a filter medium A (grain: 29 g / m ² ) made of a wet non-woven fabric.
Next, the filter medium A and a spunbonded non-woven fabric (grain: 110 g / m ² ) made of polyethylene terephthalate (PET) as the filter medium B (nonwoven fabric base material) are used, and a spunfab made of polyester (PE) (grain: 24 g / m ^{2) is used.} ) Was adhered by a laminating machine (A / B), and the filter medium A was further adhered to the filter medium B side in the same manner to obtain a water-absorbing vaporizing material (A / B / A). The evaluation results are shown in Table 1.

[Example 2]
It was the same as in Example 1 except that the fiber diameter of the nanofiber was 700 nm in Example 1. The evaluation results are shown in Table 1.

[Comparative Example 1]
In Example 1, only the filter medium A was evaluated. The evaluation results are shown in Table 1.

[Comparative Example 2]
In Example 1, only the filter medium B was evaluated. The evaluation results are shown in Table 1.

[Comparative Example 3]
In Example 1, a two-layer product in which the filter medium A and the filter medium B were adhered was evaluated. The evaluation results are shown in Table 1.

In Examples 1 and 2, the suction height on both the front side and the back side was as high as 5 cm or more. Further, Examples 1 and 2 showed high results such as a drying rate of 0.040 g / h / cm ² or more and a galley stiffness of 2000 mgf or more. In Comparative Example 1, the suction height on both the front side and the back side was as high as 5 cm or more, but the Gale rigidity and softness were low. In Comparative Example 2, the suction heights on the front side and the back side were 1 cm or less, and the water absorption was low. In Comparative Example 3, the suction height on the filter medium B side was 1 cm or less, resulting in low water absorption.

According to the present invention, there is provided a water-absorbing vaporizing material having excellent water absorption and vaporization properties and excellent rigidity, particularly for a vaporization type humidifier, and its industrial value is extremely large.

Claims (8)

A three-layer structure in which a non-woven fabric containing ultrafine fibers having a fiber diameter of 10 to 1500 nm is laminated on both surfaces of the non-woven fabric base material, and the galley stiffness of the non-woven fabric base material is higher than that of the non-woven fabric containing the ultrafine fibers. A water-absorbing and vaporizing material characterized by being composed of a body. The water-absorbing vaporizing material according to claim 1, wherein the three-layer structure has a water absorption of 5 cm or more by the Bilek method. The water-absorbing vaporizing material according to claim 1 or 2, wherein the three-layer structure is moistened with water and the drying rate measured on a heat transfer plate at 30 ° C. is 0.040 g / h / cm ² or more. The water-absorbing and vaporizing material according to any one of claims 1 to 3, wherein the ultrafine fiber is any fiber selected from the group consisting of polyester fiber, polyphenylene sulfide fiber, polyolefin fiber, and nylon fiber. The water-absorbing vaporizing material according to any one of claims 1 to 4, wherein the non-woven fabric containing the ultra-fine fibers has a content of the ultra-fine fibers of 5% by mass or more with respect to the mass of the non-woven fabric. The water-absorbing vaporizing material according to any one of claims 1 to 5, wherein the non-woven fabric containing the ultrafine fibers is a wet non-woven fabric. The water-absorbing vaporizing material according to any one of claims 1 to 6, wherein the nonwoven fabric base material is a spunbonded nonwoven fabric or a thermal-bonded nonwoven fabric. The water-absorbing vaporizing material according to any one of claims 1 to 7, which is used as a water-absorbing vaporizing material for a vaporization type humidifier.