JP5188847B2 - Humidifier element substrate - Google Patents

Description

  The present invention relates to a substrate for a humidifier element having a nonwoven fiber structure.

    A general air conditioning system creates a comfortable living environment by controlling humidity as well as air temperature. As this humidification method, water is vaporized by oscillating ultrasonic waves in the water stored in the water tank, and the water is sprayed by air stream, or the heater is placed in the water tank and heated directly to steam. There is a steam type that generates water, or a vaporization type that humidifies by adding water to the humidifying material and vaporizing moisture by applying water around it.

  In recent years, air conditioners have been downsized and various humidifiers have been commercialized for the purpose of changing the living environment and securing a large indoor space. Formability and form stability may be required.

Among these humidification methods, the vaporization method does not require energy for generating ultrasonic waves or heating, and therefore has a merit that less power is consumed and that almost no impurities are released in water. The substrate for the humidifier element is required to absorb (hold) or temporarily hold (or store) the liquid, and to release the held liquid, and in general, a nonwoven fabric or ceramic paper is used. . As a humidifying element of such a vaporizing humidifier, there has been proposed a humidifying element that forms a sheet material made of a predetermined fiber into a wave shape, assembles it into a honeycomb shape, and humidifies the resulting hollow portion by aeration ( Patent Document 1). In addition, a humidifier using a humidifying element in which a large number of voids are formed in a rectangular sheet made of a non-woven fabric using a synthetic resin having a water absorption property such as polyester or acrylic resin and alternately bent is proposed (Patent Literature). 2). However, a humidifier element substrate made of these materials is usually thin and has a hardness that is too low, and its form stability is not sufficient. Therefore, a bending process or the like is indispensable to ensure strength. For this reason, the whole humidification element becomes large and it is difficult to meet the needs such as downsizing of the apparatus.


JP 2001-59635 A Japanese Patent Laid-Open No. 2008-08498

  Accordingly, an object of the present invention is to provide a substrate for a humidifier element that has an excellent balance of liquid absorbability, liquid retention and moisture release, and also has high form stability.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that a substrate for a humidifier element having an appropriate water absorption and equilibrium moisture content having a non-woven fiber structure in which fibers are bonded by wet heat adhesive fibers. The present invention has been completed by finding that it has an excellent balance of liquid-absorbing property, liquid-retaining property, and moisture-releasing property and can improve the shape stability.

That is, the humidifier element substrate of the present invention is a humidifier element substrate that has wet heat adhesiveness and has a non-woven fiber structure, and the fibers are fixed by fusion of the wet heat adhesive fibers. In addition, it has a water absorption of 3 cm or more (Byreck method) in 600 seconds, an equilibrium moisture content of 5% or less , and a dimensional swelling rate of 0.0001 to 4% when water is absorbed in a saturated state .

  In the present invention, since the fiber has a low-density nonwoven fiber structure that is appropriately bonded by wet heat adhesive fibers, it has an excellent balance of liquid absorbency, liquid retention and moisture release, and shape stability (moderate High rigidity). That is, although the wet heat adhesive fiber has high liquid absorption and liquid retention, it has a high moisture releasing property because it has a low expansion rate due to liquid absorption. Moreover, since the form stability is high, it has a certain rigidity. Furthermore, the moldability is high, and it is easy to process into a large shape by secondary molding or the like, or to process into a small and complicated shape.

In the humidifier element base material of the present invention, the fibers are fixed by fusion of the wet heat adhesive fibers. Therefore, the web containing the wet heat adhesive fibers is heated under wet heat conditions to melt the melting point of the wet heat adhesive fibers. It can be fused as follows. In other words, a humidifier element base material with higher heat resistance can be easily manufactured. In addition, not only can heat be applied to the web under wet heat conditions, but also heat can be distributed evenly to the inside of the web as compared to a method such as hot pressing, so that the fibers in the non-woven fiber structure Can be fused uniformly, and the effect is particularly remarkable in the formation of a bulky nonwoven fiber structure. For this reason, it is excellent also in mechanical characteristics and durability, for example, it has a high bending stress even if it is lightweight and has a low density. This humidifier element base material can be composed essentially of fibers and does not require the addition of chemical binders or special chemicals, so use ingredients that generate harmful components (such as volatile organic compounds such as formaldehyde). And can be easily manufactured.
Further, the humidifier element base material may have a water absorption rate of 10 seconds or less according to JIS-L1907, a water absorption rate of 100% by mass or more, and a dimensional expansion rate by water absorption of 4% or less. . The wet heat adhesive fiber may contain an ethylene-vinyl alcohol copolymer. The base material for humidifier elements of the present invention may be composed of a plate-like molded body in which wet heat adhesive fibers are oriented substantially parallel along the surface direction.

  The substrate for a humidifier element according to the present invention includes a step of forming a fiber containing wet heat-adhesive fibers into a web, and heat-treating the generated fiber web with high-temperature steam to fuse the fibers, thereby forming a nonwoven fiber structure. It can manufacture with the manufacturing method including the process of obtaining a body.

[Humidifier element base material]
The base material for humidifier elements of the present invention contains wet heat adhesive fibers and has a non-woven fiber structure. In particular, the substrate for the humidifier element of the present invention is composed of a molded body in which fibers are fixed by fusion of the wet heat adhesive fibers, and not only high liquid absorbency and liquid retention characteristic of the fiber structure, By making the arrangement of the fibers constituting the non-woven fiber structure and the bonding state between these fibers within a predetermined range, the bending behavior (which has a high bending stress and a maximum bending stress that cannot be obtained with ordinary nonwoven fabrics) The stress is retained even if it bends past the indicated point, and the stress is to be restored when the stress is released. ”,“ Lightweight ”and“ Surface hardness (load is applied to the surface to apply force in the thickness direction. However, it is difficult to break, and at the same time, the liquid absorbing property, the liquid retaining property, the moisture releasing property, and the shape retaining property, which are important as the base material for the humidifier element, are ensured.

  Such a humidifier element base material, as will be described later, has a high temperature (overheated or heated) water vapor acting on the web containing the wet heat adhesive fibers, and has an adhesive action at a temperature below the melting point of the wet heat adhesive fibers. It is expressed and obtained by partially bonding the fibers. That is, it is obtained by point-bonding or partial-bonding single fibers and bundle-like bundled fibers so as to form a “scrum” while holding moderately small voids under wet heat.

(Wet heat adhesive fiber)
The content of the wet heat adhesive fiber can be selected from the range of 10 to 100% by weight depending on the type of the substrate for the humidifier element. When a hard humidifier element base material is required, it is preferable that the ratio of wet heat-adhesive fibers is large, and is 80% by weight or more, preferably 90% by weight or more, and more preferably 95% by weight or more. When the ratio of the wet heat adhesive fibers is within this range, a molded product that can ensure high surface hardness and bending behavior can be obtained.
The wet heat adhesive fiber is composed of at least a wet heat adhesive resin. The wet heat adhesive resin only needs to be able to flow or easily deform at a temperature that can be easily realized by high-temperature steam and to exhibit an adhesive function. Specifically, a thermoplastic resin that is softened with hot water (for example, about 80 to 120 ° C., particularly about 95 to 100 ° C.) and can be self-adhered or bonded to other fibers, for example, a cellulose-based resin (C such as methylcellulose) _1-3 alkylcelluloses, hydroxyalkyl C _1-3 alkyl celluloses such as hydroxypropyl cellulose, carboxy C _1-3 alkyl cellulose or a salt thereof, such as carboxymethyl cellulose), polyalkylene glycol resin (polyethylene oxide, poly C ₂ such as polypropylene oxide _-4 alkylene oxide), polyvinyl resins (polyvinyl pyrrolidone, polyvinyl ether, vinyl alcohol polymers, polyvinyl acetals, etc.), acrylic copolymers and alkali metal salts thereof [(meth) acrylic acid, (meth) acrylamide, etc. Copolymers containing units composed of any acrylic monomers or their salts], modified vinyl copolymers (such as vinyl monomers such as isobutylene, styrene, ethylene, vinyl ether, and maleic anhydride) Copolymer with unsaturated carboxylic acid or its anhydride or salt thereof), polymer with hydrophilic substituent introduced (polyester, polyamide, polystyrene or salt with introduced sulfonic acid group, carboxyl group, hydroxyl group, etc.) Etc.), aliphatic polyester resins (polylactic acid resins, etc.). Furthermore, among polyolefin resins, polyester resins, polyamide resins, polyurethane resins, thermoplastic elastomers or rubbers (such as styrene elastomers), it can be softened at the temperature of hot water (high-temperature steam) to exhibit an adhesive function. Other resins are also included.

These wet heat adhesive resins can be used alone or in combination of two or more. The wet heat adhesive resin is usually composed of a hydrophilic or water-soluble polymer. Among these wet heat adhesive resins, vinyl alcohol polymers such as ethylene-vinyl alcohol copolymers, polylactic acid resins such as polylactic acid, (meth) acrylic copolymers containing (meth) acrylamide units, A vinyl alcohol polymer containing an α-C _2-10 olefin unit such as ethylene or propylene, particularly an ethylene-vinyl alcohol copolymer is preferred.

  In the ethylene-vinyl alcohol copolymer, the ethylene unit content (copolymerization ratio) is, for example, about 10 to 60 mol%, preferably about 20 to 55 mol%, and more preferably about 30 to 50 mol%. When the ethylene unit is in this range, a unique property of having wet heat adhesiveness but not hot water solubility is obtained. If the proportion of the ethylene units is too small, the ethylene-vinyl alcohol copolymer easily swells or gels with low-temperature steam (water), and its form is likely to change only once wetted with water. On the other hand, when the ratio of the ethylene unit is too large, the hygroscopicity is lowered, and fiber fusion due to wet heat is difficult to be exhibited, so that it is difficult to ensure practical strength. When the ratio of the ethylene unit is particularly in the range of 30 to 50 mol%, the processability into a sheet or plate is particularly excellent.

  The saponification degree of the vinyl alcohol unit in the ethylene-vinyl alcohol copolymer is, for example, about 90 to 99.99 mol%, preferably 95 to 99.98 mol%, more preferably 96 to 99.97 mol. %. When the saponification degree is too small, the thermal stability is lowered, and the stability is lowered by thermal decomposition or gelation. On the other hand, if the degree of saponification is too large, it is difficult to produce the fiber itself.

Although the viscosity average degree of polymerization of an ethylene-vinyl alcohol-type copolymer can be selected as needed, it is 200-2500, for example, Preferably it is 300-2000, More preferably, it is about 400-1500. When the degree of polymerization is within this range, the balance between spinnability and wet heat adhesion is excellent.

  The cross-sectional shape (cross-sectional shape perpendicular to the fiber length direction) of the wet heat-adhesive fiber is a general solid cross-sectional shape, such as a round cross-section or an irregular cross-section [flat, elliptical, polygonal, 3-14 Leaf shape, T-shape, H-shape, V-shape, dogbone (I-shape, etc.)], and may be a hollow cross-section. The wet heat adhesive fiber may be a composite fiber composed of a plurality of resins including at least a wet heat adhesive resin. The composite fiber only needs to have the wet heat adhesive resin on at least a part of the fiber surface, but from the viewpoint of adhesiveness, the wet heat adhesive resin continuously occupies at least a part of the surface in the length direction. Is preferred.

  Examples of the cross-sectional structure of the composite fiber in which the wet heat adhesive fiber occupies the surface include a core-sheath type, a sea-island type, a side-by-side type, a multilayer bonding type, a radial bonding type, and a random composite type. Among these cross-sectional structures, the core-sheath structure (that is, the sheath part is wet-heat-adhesive, which is a structure in which the wet-heat adhesive resin occupies the entire surface continuously in the length direction because it is a highly adhesive structure. A core-sheath structure made of resin is preferred.

  In the case of a composite fiber, wet heat adhesive resins may be combined with each other, but may be combined with non-wet heat adhesive resins. Non-wet heat adhesive resins include water-insoluble or hydrophobic resins such as polyolefin resins, (meth) acrylic resins, vinyl chloride resins, styrene resins, polyester resins, polyamide resins, polycarbonate resins, Examples include polyurethane resins and thermoplastic elastomers. These non-wet heat adhesive resins can be used alone or in combination of two or more.

  Among these non-wet heat adhesive resins, from the viewpoint of heat resistance and dimensional stability, resins having a melting point higher than that of wet heat adhesive resins (particularly ethylene-vinyl alcohol copolymers), such as polypropylene resins and polyester resins. Resins and polyamide resins, particularly polyester resins and polyamide resins are preferred from the standpoint of excellent balance between heat resistance and fiber-forming properties.

Polyester resins include aromatic polyester resins such as poly C _2-4 alkylene arylate resins (polyethylene terephthalate (PET), polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), especially polyethylene such as PET. A terephthalate resin is preferred. In addition to the ethylene terephthalate unit, the polyethylene terephthalate resin is not limited to other dicarboxylic acids (for example, isophthalic acid, naphthalene-2,6-dicarboxylic acid, phthalic acid, 4,4'-diphenyldicarboxylic acid, bis (carboxyphenyl) ethane. , 5-sodium sulfoisophthalic acid, etc.) and diols (for example, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexane-1,4-dimethanol, Units composed of polyethylene glycol, polytetramethylene glycol, etc.) may be included at a ratio of about 20 mol% or less.

  Polyamide resins include polyamides 6, polyamides 66, polyamides 610, polyamides 10, polyamides 12, polyamides 6-12 and other aliphatic polyamides and copolymers thereof, half-synthesized from aromatic dicarboxylic acids and aliphatic diamines. Aromatic polyamide is preferred. These polyamide-based resins may also contain other copolymerizable units.

In the case of a composite fiber composed of a wet heat adhesive resin and a non-wet heat adhesive resin (fiber-forming polymer), the ratio (mass ratio) of both can be selected according to the structure (for example, core-sheath structure). The wet heat adhesive resin is not particularly limited as long as it exists on the surface. For example, wet heat adhesive resin / non-wet heat adhesive resin = 90/10 to 10/90 (for example, 60/40 to 10/90), preferably It is about 80/20 to 15/85, more preferably about 60/40 to 20/80. If the proportion of wet heat adhesive resin is too large, it will be difficult to ensure the strength of the fiber, and if the proportion of wet heat adhesive resin is too small, it will be difficult to have the wet heat adhesive resin continuously in the length direction of the fiber surface. Thus, the wet heat adhesiveness is lowered. This tendency is the same when the wet heat adhesive resin is coated on the surface of the non-wet heat adhesive fiber.

  The average fineness of the wet heat adhesive fiber can be selected, for example, from the range of about 0.01 to 100 dtex, preferably 0.1 to 50 dtex, more preferably 0.5 to 30 dtex (particularly 1 to 10 dtex) depending on the application. Degree. When the average fineness is in this range, the balance between the strength of the fiber and the expression of wet heat adhesion is excellent.

  The average fiber length of the wet heat adhesive fibers can be selected, for example, from a range of about 10 to 100 mm, preferably 20 to 80 mm, more preferably about 25 to 75 mm (particularly 35 to 55 mm). When the average fiber length is within this range, the fibers are sufficiently entangled, so that the mechanical strength of the molded body is improved.

  The crimp rate of the wet heat adhesive fiber is, for example, about 1 to 50%, preferably 3 to 40%, more preferably about 5 to 30% (particularly 10 to 20%). The number of crimps is, for example, about 1 to 100 pieces / 25 mm, preferably about 5 to 50 pieces / 25 mm, and more preferably about 10 to 30 pieces / 25 mm.

(Other fibers)
The base material for humidifier elements may further contain non-wet heat adhesive fibers. Non-wet heat adhesive fibers include polyester fibers (polyethylene terephthalate fibers, polytrimethylene terephthalate fibers, polybutylene terephthalate fibers, aromatic polyester fibers such as polyethylene naphthalate fibers), polyamide fibers (polyamide 6, polyamide 66, Aliphatic polyamide fibers such as polyamide 11, polyamide 12, polyamide 610, polyamide 612, semi-aromatic polyamide fibers, aromatic polyamide fibers such as polyphenylene isophthalamide, polyhexamethylene terephthalamide, poly p-phenylene terephthalamide, etc. ), Polyolefin fibers (poly C _2-4 olefin fibers such as polyethylene and polypropylene), acrylic fibers (acrylonitrile-vinyl chloride copolymer, etc.) Acrylonitrile fibers having rilonitrile units), polyvinyl fibers (polyvinyl acetal fibers, etc.), polyvinyl chloride fibers (polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-acrylonitrile copolymer fibers, etc.) ), Polyvinylidene chloride fiber (fiber such as vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-vinyl acetate copolymer), polyparaphenylene benzobisoxazole fiber, polyphenylene sulfide fiber, cellulosic fiber (for example, rayon fiber) , Acetate fiber, etc.)
Etc. These non-wet heat adhesive fibers can be used alone or in combination of two or more.

  These non-wet heat adhesive fibers can be appropriately selected and used according to the form of the humidifier element, the method of use, and the like. When emphasizing water absorption or the like, it is preferable to use hydrophilic fibers having high hygroscopicity, such as polyvinyl fibers or cellulose fibers, particularly cellulose fibers. Cellulosic fibers include natural fibers (cotton, wool, silk, hemp, etc.), semi-synthetic fibers (acetate fibers such as triacetate fiber), regenerated fibers (rayon, polynosic, cupra, lyocell (for example, registered trademark name: “ Tencel "etc.)). Among these cellulosic fibers, for example, semi-synthetic fibers such as rayon can be suitably used, and when combined with wet heat adhesive fibers containing an ethylene-vinyl alcohol copolymer, the affinity with wet heat adhesive fibers is high. Adhesiveness is improved, and a molded article having high mechanical properties can be obtained. Further, when hydrophilic fibers are used, for example, liquid retention, liquid absorption and moisture release with respect to an aqueous liquid are increased, while moldability and form retention tend to be decreased.

  On the other hand, when emphasizing the moisture-releasing property of aqueous liquids, hydrophobic fibers with low hygroscopicity, for example, polyolefin fibers, polyester fibers, polyamide fibers, particularly polyester fibers (polyethylene terephthalate) having an excellent balance of properties. It is preferable to use fibers. When these hydrophobic fibers are combined with wet heat adhesive fibers containing an ethylene-vinyl alcohol copolymer, a substrate for a humidifier element excellent in hydrophobicity and drainage of aqueous liquid is obtained.

  The average fineness and average fiber length of the non-wet heat adhesive fibers are the same as those of the wet heat adhesive fibers.

  The ratio (mass ratio) between the wet heat adhesive fiber and the non-wet heat adhesive fiber is also determined according to the type of the substrate for the humidifier element, etc., wet heat adhesive fiber / non-humid heat adhesive fiber = 10/90 to 100/0. (For example, it can be selected from the range of 20/80 to 100/0). When manufacturing a hard molded object, the one where the ratio of wet heat adhesive fiber is large is preferable, and the ratio (mass ratio) of both is wet heat adhesive fiber / non-wet heat adhesive fiber = 80/20 to 100/0. , Preferably 90/10 to 100/0, more preferably about 95/5 to 100/0. When the ratio of the wet heat adhesive fibers is within this range, a molded product that can ensure high surface hardness and bending behavior can be obtained. In the case of producing a molded body utilizing the characteristics of non-wet heat adhesive fibers, the ratio (mass ratio) of both is wet heat adhesive fibers / non-wet heat adhesive fibers = 10/90 to 99/1, preferably 20 / 80 to 90/10, more preferably about 30/70 to 80/20.

  The molded body (or fiber) further contains conventional additives such as stabilizers (heat stabilizers such as copper compounds, ultraviolet absorbers, light stabilizers, antioxidants, etc.), dispersants, fine particles, colorants, An antistatic agent, a flame retardant, a plasticizer, a lubricant, a crystallization rate retarder, and the like may be contained. These additives can be used alone or in combination of two or more. These additives may be carried on the surface of the molded body or may be contained in the fiber.

(Characteristics of humidifier element base material)
The substrate for a humidifier element of the present invention has a non-woven fiber structure obtained from a web composed of the fibers, the shape of which can be selected according to the application, and is a circular or elliptical cross section, or a polygonal shape. Usually, it is in the form of a sheet or plate.

  Furthermore, the humidifier element base material has a non-woven fiber structure having an appropriate rigidity (morphological stability) and a good balance between liquid absorption, liquid retention, moisture release and light weight (low density). In order to have this, it is necessary that the arrangement state and the adhesion state of the fibers constituting the nonwoven fiber web are appropriately adjusted. That is, it is desirable that the fibers constituting the fiber web are arranged so as to intersect each other while being arranged substantially parallel to the surface of the fiber web (non-woven fiber). Furthermore, it is preferable that the molded body which comprises the base material for humidifier elements is melt | fused at the intersection which each fiber crossed. In particular, a molded body that requires high form stability forms bundled fused fibers that are fused in a bundle of several to several tens at a portion where fibers other than the intersection are arranged substantially in parallel. It may be. These fibers form a “scrum” by partially forming a fused structure at the intersection of single fibers, the intersection of bundle fibers, or the intersection of single fibers and bundle fibers A structure (a structure in which fibers are bonded at an intersection and entangled like a mesh, or a structure in which fibers are bonded at an intersection to constrain adjacent fibers to each other) to achieve the desired bending behavior, surface hardness, etc. it can. In the present invention, it is desirable that such a structure is distributed substantially uniformly along the surface direction and the thickness direction of the fiber web.

The phrase “arranged approximately parallel to the fiber web surface” as used herein indicates a state where there are no repeated portions where a large number of fibers are locally arranged along the thickness direction.
More specifically, when an arbitrary cross-section of the fiber web of the formed body is observed with a microscope, the existence ratio (number ratio) of fibers continuously extending in the thickness direction over 30% or more of the thickness of the fiber web. The state is 10% or less (particularly 5% or less) with respect to the total fibers in the cross section.

  Fibers are arranged parallel to the fiber web surface when there are many fibers oriented in the thickness direction (perpendicular to the web surface) and the fiber arrangement is disturbed around the fiber web. This is because an unnecessarily large void is generated in the woven fiber, and the bending strength and surface hardness of the molded body are reduced. Therefore, it is preferable to reduce this gap as much as possible. For this purpose, it is desirable to arrange the fibers as parallel to the fiber web surface as possible. In addition, when the presence of fibers along the thickness direction is reduced to reduce the voids, the liquid retention (liquid retention or liquid retention) also decreases. In the present invention, as described later, the density of the molded body is reduced. The liquid retainability is ensured by forming a void between fibers that are lowered and oriented in parallel.

  Furthermore, in this invention, the anisotropy is provided to liquid absorption and moisture release by orientating a fiber in parallel with respect to a fiber web surface. In other words, the humidifier element substrate of the present invention has high liquid absorption and moisture release properties in the fiber length direction because the fibers have a certain orientation.

  In addition, when the web is entangled by means such as a needle punch, a high-density molded body can be easily manufactured. Furthermore, when the fibers are entangled before being wet-heat bonded, the shape of the fibers before bonding is maintained, so that it becomes easy to produce a molded product having a large thickness, which is advantageous in terms of production efficiency. However, the entanglement of the fibers by the needle punch or the like is disadvantageous in that the fibers are arranged in parallel to the fiber web surface. Furthermore, since the density of the molded body is increased by the entanglement, it is difficult to manufacture a low-density and lightweight molded body. Therefore, from the viewpoint of arranging the fibers in parallel, it is preferable that the degree of fiber entanglement is reduced or not entangled.

  In particular, when a load is applied in the thickness direction of the molded body when the molded body is in the form of a sheet or plate, if there is a large void, the void is crushed by the load and the surface of the molded body is easily deformed. . Furthermore, when this load is applied to the entire surface of the molded body, the thickness tends to be reduced as a whole. Such a problem can be avoided if the molded body itself is made of a resin filling without voids, but the liquid retaining property is lowered.

  On the other hand, in order to reduce the deformation in the thickness direction due to the load, it is conceivable to make the fibers thinner and more densely filled with the fibers, but when trying to ensure lightweight and breathability with only thin fibers, The rigidity of the fiber becomes low, and conversely the bending stress decreases. In order to secure bending stress, it is necessary to increase the fiber diameter to some extent. However, if thick fibers are simply mixed, large voids are easily formed near the intersections of the thick fibers and deformed in the thickness direction. It becomes easy to do.

  Therefore, the humidifier element base material of the present invention has a low density, and the fibers are arranged in parallel along the surface direction of the web and dispersed (or the fiber direction is directed in a random direction), thereby producing fibers. By crossing each other and adhering at the intersection, a small gap is generated to ensure liquid retention and drainage. Furthermore, an appropriate surface hardness is ensured by such a continuous fiber structure.

  Furthermore, in the humidifier element substrate of the present invention, the fiber constituting the nonwoven fiber structure is improved in the fiber adhesion rate by fusing the wet heat-adhesive fiber in order to improve the balance of liquid absorption, liquid retention and moisture release. However, it is bonded at, for example, 85% or less (for example, 1 to 85%), preferably 3 to 70%, more preferably 5 to 60% (particularly 10 to 35%). Although the fiber adhesion rate in this invention can be measured by the method as described in the Example mentioned later, the ratio of the cross section number of the fiber which adhered 2 or more with respect to the cross section number of all the fibers in a non-woven fiber cross section is shown. Therefore, a low fiber adhesion rate means that a ratio of a plurality of fibers fused to each other (a ratio of fibers fused by fusing) is small.

  In the present invention, the fibers constituting the non-woven fiber structure are bonded at the contact points of the respective fibers. In order to express a large bending stress with as few contacts as possible, this bonding point is the thickness direction. In addition, it is preferably distributed uniformly from the surface of the molded body to the inside (center) and the back surface. When the adhesion points are concentrated on the surface or inside, not only is it difficult to ensure excellent mechanical properties and moldability, but also the shape stability in the portion where the adhesion points are small is lowered.

  Therefore, in the cross section in the thickness direction of the molded body, it is preferable that the fiber adhesion rate in each region divided in three in the thickness direction is in the above range. Furthermore, the ratio of the minimum value to the maximum value of the fiber adhesion rate in each region (minimum value / maximum value) (the ratio of the minimum region to the region with the maximum fiber adhesion rate) is, for example, 50% or more (for example, 50 to 100%), preferably 55 to 99%, more preferably 60 to 98% (especially 70 to 97%). In the present invention, since the fiber adhesion rate has such uniformity in the thickness direction, it is excellent in hardness, bending strength, folding resistance and toughness.

  In the present invention, the “region divided into three in the thickness direction” means each region divided into three equal parts by slicing in a direction orthogonal to the thickness direction of the plate-like molded body.

  As described above, in the humidifier element substrate of the present invention, not only the fusion by the wet heat adhesive fibers is uniformly dispersed and point-bonded, but also these point bonds have a short fusion point distance (for example, The network structure is stretched densely by several tens to several hundreds μm). With such a structure, the liquid holding material of the present invention has a high followability to strain due to the flexibility of the fiber structure even when an external force acts, and each fusion point of finely dispersed fibers. Therefore, it can be estimated that high folding resistance and toughness are expressed. On the other hand, conventional porous molded bodies and foams form an interface in which the periphery of the pores is continuous. Therefore, compared with the humidifier element base material of the present invention, external force is applied in a large area. It is assumed that distortion is likely to occur, and folding resistance and toughness are reduced.

In the humidifier element substrate of the present invention, the existence frequency of single fibers (single fiber end faces) in the cross section in the thickness direction is not particularly limited. For example, the existence frequency of single fibers existing in any 1 mm ^{2 of the} cross section is Although the average may be 100 pieces / mm ² or more (for example, about 100 to 300 pieces / mm ² ), in particular, when mechanical properties are required rather than lightweight, For example, an average of 100 pieces / mm ² or less, preferably 60 pieces / mm ² or less (for example, 1 to 60 pieces / mm ² ), more preferably 25 pieces / mm ² or less (for example, 3 to 25 pieces / mm ² ). It may be. When the presence frequency of the single fiber is too high, the fusion of the fibers is small and the strength of the molded body is lowered. If the frequency of single fibers exceeds 100 fibers / mm ² , bundle fusion of fibers decreases, making it difficult to ensure high bending strength. Furthermore, in the case of a plate-shaped molded body, it is preferable that the fibers fused in a bundle shape are thin in the thickness direction of the molded body and have a wide shape in the surface direction (length direction or width direction).

In the present invention, the existence frequency of the single fiber is measured as follows. That is, the range corresponding to 1 mm ² selected from the scanning electron microscope (SEM) photograph of the cross section of the compact is observed, and the number of single fiber cross sections is counted. Arbitrary several places (for example, 10 places selected at random) are observed in the same manner, and the average value per unit area of the single fiber end face is defined as the existence frequency of single fibers. At this time, all the number of fibers in a single fiber state are counted in the cross section. That is, in addition to fibers that are completely in a single fiber state, even if a plurality of fibers are fused, a fiber that is separated from the fused portion in the cross section and is in a single fiber state is counted as a single fiber.

  The molded body including such a bundle-like fused fiber appropriately balances liquid absorption, liquid retention and moisture release, rigidity (shape stability) such as bending strength and surface hardness, and light weight. For this reason, it is preferable that the frequency of existence of the bundle-like fused fiber is low, and the fibers are bonded at a high frequency at the intersection of each fiber (bundle fiber and / or single fiber). However, if the fiber adhesion rate is too high, the distances between the bonded points are too close to each other, the flexibility is lowered, and it becomes difficult to eliminate distortion due to external stress. For this reason, the molded body needs to have a fiber adhesion rate of 85% or less. When the fiber adhesion rate is not too high, a passage by a fine gap can be secured in the molded body, and the lightness, liquid retention and moisture release can be improved. In addition, by forming an appropriate passage without the gap being too wide, the affinity of the fiber to the liquid and the capillary action can be expressed and the liquid absorbency can be improved. Therefore, in order to express a large bending stress, surface hardness, liquid retention and moisture release with as few contacts as possible, the fiber adhesion rate increases in the thickness direction from the molded body surface to the inside (center) and back surface. It is preferable to distribute uniformly along. When the adhesion points are concentrated on the surface or inside, in addition to the above-described bending stress and shape stability, an appropriate gap cannot be formed, and it becomes difficult to ensure liquid retention and moisture release. In addition, if the adhesion point is non-uniform, it is not possible to obtain an appropriately sized gap, the amount of liquid retained is reduced in a small part of the gap, and the liquid holding power is reduced in a large part of the gap, Liquid retention is reduced.

  One feature of the humidifier element substrate of the present invention is that it has high toughness and bending stress and exhibits excellent bending behavior. In the present invention, in order to express this bending behavior, the repulsive force of the sample generated when the sample is gradually bent is measured according to JIS K7017 “Fiber-Reinforced Plastics—How to Obtain Bending Properties”, and the maximum stress (peak stress) is measured. ) As a bending stress and used as an index of bending behavior. That is, the larger the bending stress, the harder the molded body, and the more the bending amount (displacement) until the measurement object breaks, the better the curved body.

  In the humidifier element substrate of the present invention, the maximum bending stress in at least one direction (preferably in all directions) is 0.05 MPa or more (for example, 0.05 to 100 MPa), preferably 0.1 to 30 MPa, More preferably, it may be about 0.2 to 20 MPa. If the maximum bending stress is too small, it is easily broken by its own weight or a slight load when used in a plate shape. Further, if the maximum bending stress is too high, it becomes too hard, and if it is bent beyond the peak of the stress, it is easily broken and broken. In addition, in order to obtain hardness exceeding 100 MPa, it is necessary to increase the density of the molded body, and it is difficult to ensure light weight and liquid retention.

  Looking at the correlation between the bending amount (displacement) and the bending stress caused by the bending amount, the stress increases as the bending amount increases. For example, the bending amount increases approximately linearly. In the humidifier element substrate of the present invention, when the measurement sample reaches a specific bending amount, the stress gradually decreases thereafter. That is, when the amount of bending and the stress are graphed, a correlation is shown in which an upward convex parabola is drawn. The base material for a humidifier element of the present invention exceeds the maximum bending stress (bending stress peak) and does not cause a sudden drop in stress even when attempting to bend, so-called “stickiness (or toughness)”. It is also one of the features. In the present invention, as an index representing such “stickiness”, the bending stress remaining in a state exceeding the bending amount (displacement) at the peak of the bending stress can be used. That is, the humidifier element base material of the present invention is a stress when bent to a displacement of 1.5 times the bending amount showing the maximum bending stress (hereinafter sometimes referred to as “1.5 times displacement stress”). However, it is sufficient to maintain 1/5 or more (for example, 1/5 to 1) of the maximum bending stress, for example, 1/3 or more (for example, 1/3 to 9/10), preferably 2/5. It may be maintained above (for example, 2/5 to 9/10), more preferably 3/5 or more (for example, 3/5 to 9/10). The double displacement stress is 1/10 or more (for example, 1/10 to 1) of the maximum bending stress, preferably 3/10 or more (for example, 3/10 to 9/10), more preferably 5/10. You may maintain above (for example, 5 / 10-9 / 10).

  The humidifier element substrate of the present invention can ensure high lightness due to the gaps formed between the fibers. In addition, since these voids are not independent voids but are continuous, they have high moisture release properties in addition to high air permeability. Such a structure is a structure that is extremely difficult to produce by conventional hardening methods such as a method of impregnating a resin and a method of forming a film-like structure by closely adhering surface portions. .

That is, the apparent density of the base material for the humidifier element of the present invention can be selected from the range of about 0.01 to 0.3 g / cm ³ depending on the application, while maintaining the form stability, From the point of maintaining the balance between liquid retention and moisture release, for example, 0.03 to 0.25 g / cm ³ , preferably 0.05 to 0.20 g / cm ³ , more preferably 0.05 to 0.15 g. / Cm ³ (particularly 0.07 to 0.13 g / cm ³ ). If the apparent density is too low, the liquid retention is improved, but the surface hardness, mechanical properties, and moldability are reduced. Conversely, if the apparent density is too high, mechanical properties such as liquid absorbency and hardness can be secured. , Liquid retention is reduced. When the density decreases, the fibers become entangled and become close to a general non-woven fiber structure in which the fibers are fused at the intersections. On the other hand, when the density is increased, the fibers are fused in a bundle, and the porous molded body. It becomes a structure close to.

Basis weight of the humidifier element substrate for, for example, be selected from 50~5000g / m ² approximately, preferably in the range of 100 to 3000 g / m ^2, more preferably 150~1000g / m ² (in particular 200 to 800 g / m ² ) About. If the basis weight is too small, it will be difficult to ensure hardness and formability. If the basis weight is too large, the web will be too thick, and high-temperature steam will not be able to sufficiently enter the inside of the web in wet heat processing, and it will be uniform in the thickness direction. It becomes difficult to make a simple structure.

  When the base material for humidifier elements of this invention is plate shape or sheet shape, the thickness is not specifically limited, but can be selected from the range of about 0.5 to 500 mm, for example, 1 to 100 mm, preferably 1. It is 5-50 mm, More preferably, it is about 2-20 mm. If the thickness is too thin, it will be difficult to ensure the hardness, and if it is too thick, the ratio of the surface area that releases the contained moisture will be low, and the efficiency of humidifying the air will be reduced. Even if the humidifier element substrate of the present invention forms a bulky structure, the wet heat adhesive fibers can be uniformly fused to the inside, so that it can be a highly self-supporting bulky humidifier element substrate. Moreover, since the base material for humidifier elements of this invention has high moldability, a more bulky structure can be easily created by stacking a plurality of sheets and subjecting them to heat treatment (for example, wet heat treatment).

Since the base material for humidifier elements of the present invention has a non-woven fiber structure, the air permeability is high. Specifically, the air permeability according to the fragile method is 0.1 cm ³ / (cm ² · sec) or more [eg, 0.1 to 300 cm ³ / (cm ² · sec)], preferably 0.5 to 250 cm ³ / (Cm ² · sec) [for example, 1 to 250 cm ³ / (cm ² · sec)], more preferably about 5 to ²⁰⁰ cm ³ / (cm ² · sec), and usually 1 to 100 cm ³ / (cm ²・ Second). If the air permeability is too small, the moisture release performance is lowered. On the other hand, if the air permeability is too high, the moisture release property is increased, but the fiber voids in the molded body are too large, and the bending stress, the liquid absorption property, and the liquid retention property are lowered.

  The humidifier element substrate of the present invention has a high water absorption rate, excellent liquid absorption and moisture release properties, and high liquid retention. Specifically, the water absorption rate of the humidifier element substrate is a method according to the JIS L1907 dropping method, for example, 10 seconds or less, preferably 5 seconds or less, and more preferably 1 second or less. The water absorption rate (water retention rate) is, for example, 100% by mass or more, preferably 200% by mass or more (for example, 200 to 5000% by mass), more preferably 500% by mass or more (for example, according to JIS L1907). 500-3000 mass%).

Furthermore, when using as a humidifier element, the water absorption (Byreck method) which sucks up water above a liquid level is useful. This is because the larger the capacity, the larger the contact area with the air in the humidifier element when humidifying the air. In the present invention, in order to develop sufficient water absorption, this value after 600 seconds from the start of water absorption needs to be 3 cm or more, preferably 4 cm or more, more preferably 5 cm or more.

On the other hand, the humidifier element substrate of the present invention needs to secure moisture for humidifying air more quickly and to release this moisture into the air more quickly. That is, it is preferable that the humidifier element itself of the present invention has a low force for holding water. This force can be expressed by an equilibrium moisture content, and the value is preferably 5% or less, more preferably 4% or less, and still more preferably 3% or less.
Similarly, it can be said that moisture is quickly released because of the high drying rate.

  Moreover, since the base material for humidifier elements of this invention has high form stability, even if it absorbs water | moisture content, there is little expansion | swelling of a volume. At the same time, it is difficult for a substrate having water absorbency with large deformation to exhibit good moisture-releasing properties, so it is necessary to make this balance within a good range. Specifically, the dimensional expansion rate when water is sufficiently absorbed (saturated) (for example, in the case of a plate-like molded body, the respective dimensional expansion rates in the vertical direction, the horizontal direction, and the thickness direction) is, for example, 4% or less (for example, 0.0001 to 4%), preferably 0.001 to 3.5%, and more preferably 0.01 to 3% (particularly 0.1 to 2%).

By using the humidifier element base material of the present invention as an element by having the above-described form stability, water retention, and moisture release properties, a large number of these elements are raised in the form of fins from the water absorption part, It is possible to humidify the air as it passes around it. Moreover, when a large humidification capability is required, it can be compensated by raising the fins in the air passage in parallel at appropriate intervals. Therefore, it is possible to contact and humidify the air while maintaining the form without using a complicated shape such as a honeycomb structure as in the case of using conventional paper or nonwoven fabric.

[Method of manufacturing substrate for humidifier element]
In the method for manufacturing a substrate for a humidifier element of the present invention, first, the fiber containing the wet heat adhesive fiber is formed into a web. As a method for forming the web, a conventional method, for example, a direct method such as a spunbond method or a meltblowing method, a card method using meltblown fibers or staple fibers, a dry method such as an airlay method, or the like can be used.

  Among these methods, a card method using melt blown fibers or staple fibers, particularly a card method using staple fibers is widely used. Examples of the web obtained using staple fibers include a random web, a semi-random web, a parallel web, and a cross-wrap web. Of these webs, a semi-random web and a parallel web are preferred when the proportion of bundled fused fibers is increased.

  Next, the obtained fiber web is sent to the next step by a belt conveyor, and then exposed to superheated or high-temperature steam (high-pressure steam) flow to obtain a shaped body having a non-woven fiber structure. That is, when the fiber web transported by the belt conveyor passes through the high-speed high-temperature steam flow ejected from the nozzle of the steam spraying device, the wet-heat adhesive fibers are fused by the sprayed high-temperature steam, and the fiber Each other (wet heat adhesive fibers or wet heat adhesive fibers and other fibers) are three-dimensionally bonded. In particular, since the fiber web in the present invention has air permeability, high-temperature water vapor penetrates into the inside, and a molded body having a substantially uniform fusion state can be obtained.

  The belt conveyor to be used is not particularly limited as long as it can be subjected to high-temperature steam treatment while basically compressing the fiber web used for processing to a desired density, and an endless conveyor is preferably used. In addition, it may be a general single belt conveyor, or may be transported by combining two belt conveyors as necessary and sandwiching the web between both belts. By carrying in this way, when processing a fiber web, it can suppress that the form of the fiber web conveyed by external forces, such as water used for processing, high temperature steam, and vibration of a conveyor, changes. It is also possible to control the density and thickness of the processed non-woven fibers by adjusting the distance between the belts.

In order to supply water vapor to the fiber web, a conventional water vapor jet apparatus is used. As this steam spraying device, a device capable of spraying steam substantially uniformly over the entire width of the web at a desired pressure and amount is preferable. When two belt conveyors are combined, water vapor is supplied to the web through a water-permeable conveyor belt or a conveyor net placed on the conveyor. A suction box may be attached to the other conveyor. Excess water vapor that has passed through the fiber web can be sucked and discharged by the suction box. Further, in order to perform steam treatment on both sides of the front and back of the fiber web at a time, in a conveyor opposite to the conveyor on which the steam spraying device is mounted, more than the portion on which the steam spraying device is mounted. You may install another water vapor | steam injection apparatus in the conveyor of a downstream part. If there is no downstream steam injection device and suction box, and if you want to steam-treat the front and back of the fiber web, you can reverse the front and back of the fiber web that has been treated once and pass it through the processing device again. Good.

The endless belt used for the conveyor is not particularly limited as long as it does not hinder the conveyance of the fiber web or the high-temperature steam treatment. However, when high-temperature steam treatment is performed, the surface shape of the belt may be transferred to the surface of the fiber web depending on the conditions. In particular, when it is desired to obtain a molded body having a flat surface, a net with a fine mesh may be used. The upper limit is about 90 mesh, and a net that is roughly coarser than 90 mesh (for example, a net of about 10 to 50 mesh) is preferable. A finer mesh net than this has low air permeability and makes it difficult for water vapor to pass through. The mesh belt is made of metal, heat-treated polyester resin, polyphenylene sulfide resin, polyarylate resin (fully aromatic polyester resin), aromatic polyamide resin, etc. The heat resistant resin is preferable.

Since the high-temperature steam sprayed from the steam spraying device is an air stream, unlike the hydroentanglement process or the needle punch process, the fibers in the fiber web that is the object to be processed enter the inside of the fiber web without largely moving. . It is considered that due to the invasion action and wet heat action of the water vapor flow into the fiber web, the water vapor flow efficiently covers the surface of each fiber existing in the fiber web in a wet heat state, and uniform heat bonding becomes possible. In addition, since this treatment is performed in a very short time under a high-speed air flow, the heat conduction of the water vapor to the fiber surface is sufficient, but the treatment is completed before the heat conduction to the inside of the fiber is sufficiently achieved. For this reason, the entire fiber web to be processed is not easily crushed or deformed such that its thickness is impaired by the pressure or heat of high-temperature steam. As a result, the wet heat bonding is completed so that the degree of bonding in the surface and the thickness direction is substantially uniform without causing large deformation in the fiber web. Further, since heat can be sufficiently conducted to the inside of the non-woven fiber structure as compared with the dry heat treatment, the degree of fusion in the surface and the thickness direction becomes substantially uniform.

Furthermore, when obtaining a molded body having a high surface hardness and bending strength, when the high-temperature steam is supplied to the web for processing, the web to be processed is placed between a conveyor belt or rollers with a desired apparent density (for example, , About 0.3 to 1 g / cm ³ ), and exposure to high temperature water vapor is important. In particular, when trying to obtain a relatively high-density molded body, it is necessary to compress the fiber web with sufficient pressure when processing with high-temperature steam. Furthermore, it is also possible to adjust to a target thickness and density by securing an appropriate clearance between rollers or between conveyors. In the case of a conveyor, since it is difficult to compress the web at a stretch, it is preferable to set the belt tension as high as possible and gradually narrow the clearance from the upstream of the steam treatment point. Furthermore, it is processed into a molded body having desired bending hardness, surface hardness, lightness, and air permeability by adjusting the steam pressure and the processing speed.

  At this time, if it is desired to increase the hardness, the back side of the endless belt on the opposite side of the nozzle across the web is made of a stainless steel plate or the like so that the steam cannot pass through. Since it reflects here, it adhere | attaches more firmly by the heat retention effect of vapor | steam. Conversely, when light adhesion is required, a suction box may be provided to discharge excess water vapor to the outside.

  The nozzle for injecting the high-temperature steam may be a plate or a die in which predetermined orifices are continuously arranged in the width direction, and may be arranged so that the orifices are arranged in the width direction of the fiber web to be supplied. There may be one or more orifice rows, and a plurality of rows may be arranged in parallel. A plurality of nozzle dies having a single orifice array may be installed in parallel.

  When using a type of nozzle having an orifice in the plate, the thickness of the plate may be about 0.5 to 1 mm. The orifice diameter and pitch are not particularly limited as long as the target fiber fixation is possible, but the orifice diameter is usually 0.05 to 2 mm, preferably 0.1 to 1 mm, more preferably. It is about 0.2 to 0.5 mm. The pitch of the orifices is usually about 0.5 to 3 mm, preferably about 1 to 2.5 mm, and more preferably about 1 to 1.5 mm. If the orifice diameter is too small, the processing accuracy of the nozzle becomes low and the processing becomes difficult, and the operational problem that clogging is likely to occur easily occurs. On the other hand, if it is too large, the water vapor jetting power is reduced. On the other hand, if the pitch is too small, the nozzle holes become too dense and the strength of the nozzle itself is reduced. On the other hand, when the pitch is too large, there is a case where high-temperature water vapor does not sufficiently hit the web, so that the web strength is lowered.

  The high-temperature steam is not particularly limited as long as the target fiber can be fixed, and may be set according to the material and form of the fiber used. The pressure is, for example, 0.1 to 2 MPa, preferably 0.2 to The pressure is about 1.5 MPa, more preferably about 0.3 to 1 MPa. If the water vapor pressure is too high or too strong, the fibers that make up the web may move more than necessary, causing turbulence, or the fibers may melt too much to partially retain the fiber shape. There is. On the other hand, if the pressure is too weak, it may not be possible to give the web the amount of heat necessary for fiber fusion, or water vapor may not penetrate the web, resulting in fiber fusion spots in the thickness direction. In addition, it may be difficult to control the uniform ejection of water vapor from the nozzle.

  The temperature of the high-temperature steam is, for example, about 70 to 150 ° C, preferably about 80 to 120 ° C, and more preferably about 90 to 110 ° C. The processing speed of the high temperature steam is, for example, 200 m / min or less, preferably 0.1 to 100 m / min, and more preferably about 1 to 50 m / min.

  If necessary, it is also possible to impart designability to a molded body obtained by applying predetermined uneven patterns, characters, pictures, etc. to the conveyor belt and transferring them. Further, it may be laminated with other materials to form a laminated body, or may be processed into a desired form (various shapes such as a columnar shape, a quadrangular prism shape, a spherical shape, an ellipsoidal shape) by molding. In particular, in the present invention, since it is hard and excellent in shape stability, it can be processed into various shapes without impairing the properties related to the absorption and release of liquid such as liquid absorption, liquid retention and moisture release.

  After the fibers of the fiber web are partially wet-heat bonded in this way, moisture may remain in the resulting molded body having the nonwoven fiber structure, and the web may be dried as necessary. As for drying, it is necessary that the surface of the molded body in contact with the heating body for drying does not lose the fiber form due to the heat of drying so that the fiber form does not disappear, and a conventional method can be used as long as the fiber form can be maintained. . For example, a large dryer such as a cylinder dryer or tenter used for drying nonwoven fabrics may be used, but the remaining moisture is very small and can be dried by a relatively light drying means. Therefore, a non-contact method such as far-infrared irradiation, microwave irradiation, electron beam irradiation, or a method of blowing or passing hot air is preferable.

  Furthermore, as described above, the molded body is obtained by adhering wet heat adhesive fibers with high-temperature steam, but partially (such as bonding between molded bodies obtained by wet heat bonding), other conventional methods, For example, you may adhere | attach by processing methods, such as partial hot-pressure melt | fusion (hot embossing etc.) and mechanical compression (needle punch etc.).

  The wet heat adhesive fibers can also be fused by dipping the fiber web in hot water. However, it is difficult to control the fiber adhesion rate by such a method, and a molded product with high uniformity of the fiber adhesion rate is obtained. Is difficult. The reason for this is that the wet heat adhesiveness differs depending on the position due to the air contained in the fiber web, the influence on the structure caused by this air being pushed out of the fiber web, the wet heat bonded fiber web It can be presumed that the deformation of the fine structure inside the fiber by the take-off roller when taking out from the hot water or the difference in the deformation of the fine structure in the vertical direction due to the weight of the hot water contained in the taken-out fiber web.

  The base material for a humidifier element of the present invention is excellent in the balance between liquid absorption, liquid retention, moisture release and form stability, so as to keep its form and keep its surface area large like conventional elements. It does not require complicated processing such as a honeycomb structure, and can be used for offices and houses such as houses and vehicles.

  Specifically, the substrate for a humidifier element of the present invention has a rapid liquid absorption speed, high liquid absorbency and liquid retention, and quick moisture release. Moreover, since it has moderate hardness, it is excellent in moldability, and a relatively small molded body has high form stability. Therefore, the humidifier element substrate of the present invention is also suitable for a humidifier that requires a small and complicated structure.

  Furthermore, the base material for humidifier elements of the present invention is suitable for use in houses, vehicles, and the like because of its excellent balance of moisture absorption, retention and release. Among these, from the point of having high water absorption, water retention and drainage, it is also suitable for humidifiers that need to quickly release moisture without retaining the collected water.

  The shape of such a humidifier element base material can be selected according to the location of the storage (storage chamber) to be provided and the shape of the member, for example, plate shape (flat plate shape, curved plate shape, bent plate shape, etc.) It is cylindrical. Of these, the humidifier element base material is usually disposed in the vicinity of the inner wall (side wall, ceiling, floor, etc.) of the storage, and therefore the shape thereof is usually plate-like. When the humidifier element base material is arranged on the side wall of the storage case, the side wall of the storage case is arranged so that the surface direction of the humidifier element base material is parallel to the surface direction of the side wall in consideration of the fiber orientation. It is preferable to arrange | position along. Thus, by arrange | positioning the base material for humidifier elements, the water | moisture content collected by the board surface can be drained in the direction along the side wall of a storage. In addition, when the base material for humidifier elements is a comparatively big plate-shaped molded object, you may combine with reinforcement members, such as a frame body and plate-shaped body comprised with the metal, the plastics, etc. as needed.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. Each physical property value in the examples was measured by the following method. In the examples, “%” is based on mass unless otherwise specified.

(1) Weight per unit (g / m ² )
Measured according to JIS L1913 “Testing method for general short fiber nonwoven fabric”.

(2) Thickness (mm), apparent density (g / cm ³ )
The thickness was measured according to JIS L1913 “General Short Fiber Nonwoven Fabric Testing Method”, and the apparent density was calculated from this value and the basis weight value.

(3) Number of crimps Evaluation was made according to JIS L1015 “Testing method for chemical fiber staples” (8.12.1).

(4) Air permeability Measured by the fragile method according to JIS L1096.

(5) Fiber Adhesion Rate Using a scanning electron microscope (SEM), a photograph was taken with the cross section of the molded body magnified 100 times. The photograph of the cross section in the thickness direction of the photographed molded product is divided into three equal parts in the thickness direction, and the number of fiber cut surfaces (fiber end faces) that can be found in each of the three divided regions (front surface, inside (center), back surface) On the other hand, the ratio of the number of cut surfaces where the fibers are bonded to each other was determined. Of the total number of fiber cross sections that can be found in each region, the ratio of the number of cross sections in a state where two or more fibers are bonded is expressed as a percentage based on the following formula. In addition, in the part which fibers contact, there exists a part which is simply contacting, without melt | fusion, and a part which has adhere | attached by melt | fusion. However, by cutting the molded body for microscopic photography, the fibers in contact with each other are separated from each other by the stress of each fiber on the cut surface of the molded body. Therefore, in the cross-sectional photograph, it can be determined that the contacting fibers are bonded to each other.

Fiber adhesion rate (%) = (number of cross sections of fibers bonded two or more) / (total number of cross sections of fibers) × 100

However, for each photograph, all the fibers with visible cross sections were counted, and when the number of fiber cross sections was 100 or less, a photograph to be observed was added so that the total fiber cross section number exceeded 100. In addition, the fiber adhesion rate was calculated | required about each area | region divided into three equally, and the uniformity in the thickness direction was computed from the ratio of the maximum value and the minimum value.

(6) Bending stress It measured according to A method (three-point bending method) among the methods as described in JIS K7017. At this time, the measurement sample was a 25 mm wide × 80 mm long sample, the distance between fulcrums was 50 mm, and the test speed was 2 mm / min. In the present invention, the maximum stress (peak stress) in this measurement result chart is defined as the maximum bending stress. The bending stress was measured in the MD direction and the CD direction. Here, the MD direction refers to a state in which the measurement sample is collected so that the web flow direction (MD) is parallel to the long side of the measurement sample, while the CD direction refers to the long side of the measurement sample. A state in which a measurement sample is collected so that the web width direction (CD) is parallel.

(7) 1.5 times displacement stress In the measurement of bending stress, the stress when the bending amount (displacement) exceeding the maximum bending stress (peak stress) is exceeded and further bent to 1.5 times the displacement is continued. The displacement stress was 1.5 times.

(8) Water absorption rate (wicking method)
The water absorption rate was measured according to JIS-L1907 “Test method for water absorption of textile products”. One drop of 0.05 g / droplet of water from a height of 10 mm was dropped on the sample, and the time until the drop was sucked into the sample was measured.

(9) Water absorption (Bilec method)
The water absorption was measured according to JIS-L1907 “Test method for water absorption of textile products”. Measurement was performed at 10 seconds, 30 seconds, 60 seconds, 300 seconds, and 600 seconds.

(10) Water retention rate (water absorption rate)
Measured according to JIS L1907 “Water absorption”. A sample of 5 cm × 5 cm square size is prepared and the mass (molded body mass) is measured. This sample was submerged in water for 30 seconds, then pulled up, suspended for 1 minute in the air with one corner up, the surface water was drained, and the mass (mass after water absorption) was measured. It calculated based on the following formula | equation.

Water absorption rate = (mass after water absorption−molded body mass) / molded body mass × 100 (mass%)

(11) Expansion coefficient upon water absorption After the sample was cut to the same size as the water retention test and allowed to stand for 24 hours under the same conditions, the dimensions under the standard condition (L1) were measured in the MD direction, CD direction, and thickness direction. After immersing the sample in an amount of distilled water that can completely cover the sample for 5 minutes, pulling it up and suspending it vertically for 1 minute, draining it in the same way, then length, width and thickness of the sample. The dimension after water absorption (L2) was measured and the dimensional change rate was calculated according to the following formula. For each measurement value, an average value of values measured for five samples was used.

Dimensional change rate = [(L2) − (L1)] / (L1) × 100 (%)

(12) Initial drying speed A sample was cut into a 10 cm square, and the sample was left in a standard state (20 ± 2 ° C., 65 ± 4% RH) for 24 hours in a large amount of distilled water. After immersion for 30 minutes, the sample was taken out with tweezers and held in the air for 1 minute to remove excess moisture. The sample was immediately measured for weight (wt) and immediately put in a constant temperature and humidity chamber set to 40 ° C. and 65 RH%. The sample was allowed to stand for 3 hours in a constant temperature and humidity chamber, and then the weight was measured. At this time, the average weight reduction per hour was defined as the initial drying speed.

Initial drying rate = (wt-w1) / 3 (g / hr)

(13) Moisture release sample The sample was cut into 5 cm width x 20 cm length, and after immersing this sample in a vat with water more than twice the thickness of the sample for 1 minute, the sample was suspended in the air for 1 minute. Added a lot of moisture. The weight of this sample was measured (wa). The sample was suspended in a 300 ml beaker containing water so that the height of water was 7 cm so that the height of the sample immersed in water was 5 cm. Hot air of a dryer (manufactured by National, EH602 type, heater capacity 600 W) was applied to the sample at a height of 5 cm from the water surface for 10 minutes. The hot air at this time was wind speed 12-15 m / min and 74-76 degreeC on the sample surface. Thereafter, the weight of the sample was measured (wb). From these values, the moisture release rate was calculated by the following equation.

Moisture release rate = (wa−wb) / wa × 100 (%)

(14) Equilibrium moisture content The sample was cut to a size of 10 cm square, and the weight of the sample was measured after leaving the sample in a standard state (20 ± 2 ° C., 65 ± 4% RH) for 24 hours (wc )did. This sample was dried by treating at 140 ° C. for 8 hours in a hot air dryer, and the dry weight was measured (wd). From these values, the equilibrium moisture content was calculated according to the following formula.

Equilibrium moisture content (%) = (wc−wd) / wd × 100 (%)

(15) Shape retention A non-woven fiber sample was cut into a 5 mm square cube shape and charged into an Erlenmeyer flask (100 cm ³ ) containing 50 cm ³ of water. This flask was mounted on a shaker (manufactured by Yamato Scientific Co., Ltd., “MK160 type”), and was shaken at a speed of 60 rpm for 30 minutes by a swirling method with an amplitude of 30 mm. After shaking, the morphological change and morphological retention state were visually observed and evaluated in three stages according to the following criteria.

(Double-circle): The shape before a process is substantially hold | maintained.
○: Large missing part is not seen, but deformation of form is seen.
X: Occurrence of missing parts is observed.

Example 1
As a wet heat adhesive fiber, a core-sheath type composite staple fiber having a core component of polyethylene terephthalate and a sheath component of ethylene-vinyl alcohol copolymer (ethylene content 44 mol%, saponification degree 98.4 mol%) ) "Kuraray", "Sophista", fineness 2.2dtex, fiber length 51mm, core-sheath mass ratio = 50/50, number of crimps 21 / 25mm, crimp rate 13.5%).

Using this core-sheath type composite staple fiber, a card web having a basis weight of about 100 g / m ² was prepared by a card method, and three webs were stacked to form a card web having a total basis weight of about 300 g / m ² . The card web was transferred to a belt conveyor equipped with a 50 mesh, 500 mm wide stainless steel endless net. In addition, the belt conveyor which has the same metal mesh is equipped in the upper part of the metal mesh of this belt conveyor, and it rotated in the same direction at the same speed, respectively, and used the belt conveyor which can adjust the space | interval of these metal meshes arbitrarily. .

  Next, the steam web is introduced into the steam jetting device provided in the lower conveyor, and steam treatment is performed by ejecting 0.4 MPa high-temperature steam from the device in the thickness direction of the card web (perpendicularly). As a result, a molded body having a non-woven fiber structure was obtained. In this steam spraying device, a nozzle is installed in the lower conveyor so as to spray high-temperature steam toward the web via a conveyor net, and a suction device is installed in the upper conveyor. Further, another jetting device, which is a combination of the arrangement of the nozzle and the suction device reversed, is installed on the downstream side in the web traveling direction of the jetting device, and steam treatment is performed on both the front and back sides of the web. did.

  In addition, the hole diameter of the water vapor | steam injection nozzle was 0.3 mm, and the vapor | steam injection apparatus with which the nozzle was arranged in 1 row at 1 mm pitch along the width direction of the conveyor was used. The processing speed was 3 m / min, and the interval (distance) between the upper and lower conveyor belts on the nozzle side and the suction side was 2.5 mm. The nozzles were arranged on the back side of the conveyor belt so as to be almost in contact with the belt.

  The obtained molded body had a board-like form. This was cut into a belt conveyor flow direction (MD direction) of 647 mm and a width direction (CD direction) of 400 mm to obtain a humidifier element substrate of the present invention. Moreover, the sample for evaluation was cut out from the obtained base material for humidifier elements. The evaluation results are shown in Table 1.

Example 2
A core-sheath type composite staple fiber (manufactured by Kuraray Co., Ltd., “Sophista”) and rayon fiber (fineness: 1.4 dtex, fiber length: 44 mm) are blended at a ratio of 60/40 (mass ratio) to a weight of about 100 g / m The card web of No. ² was prepared and five sheets were stacked, and the base material for the humidifier element was the same as in Example 1 except that the distance (distance) between the upper and lower conveyor belts on the nozzle side and the suction side was 5 mm. Manufactured. The evaluation results of the obtained humidifier element substrate are shown in Table 1.

Example 3
The same card web as in Example 1 (approx. 100 g / m ² ) is stacked five times, and the interval (distance) between the upper and lower conveyor belts on the nozzle side and the suction side is 5 mm. Thus, a base material for a humidifier element was manufactured. The evaluation results of the obtained humidifier element substrate are shown in Table 1.

Comparative Example 1
Using a web made of 100% rayon fibers used in Example 2 (approx. 100 g / m ² ), water flow is ejected at a pressure of 8 MPa from a nozzle hole of 0.3 mmΦ and 1 mm pitch in a state where four webs are stacked. And then integrating the acrylic binder resin (manufactured by Nippon Carbide Co., Ltd.) with a front and back sides of about 40 g / m ² respectively, and a substrate for a humidifier element comprising a hydrophilic nonwoven fabric to which fibers are fixed. Got. The evaluation results are shown in Table 1.

  As is clear from the results in Table 1, the humidifier element base materials of the examples have a uniform fiber adhesion rate in the thickness direction, high bending stress, excellent shape stability, and excellent water absorption characteristics. Yes. In particular, the humidifier element substrate of Example 1 is relatively excellent in balance of various properties.

In addition, in the base material for humidifier elements of Example 2, the fiber fusion | melting point has decreased by mixing of the rayon fiber. In addition, the conveyor interval is widened to produce a low-density molded body. Therefore, since the density is low and the fiber adhesion rate is low, the bending strength and the shape retention are reduced. On the other hand, since it has a low density structure and contains rayon, the water absorption speed is high. However, because of low fiber density and low expression level of capillary action, the wicking test value by the Bayrec method is slightly lowered.
On the other hand, the water absorption expansion coefficient becomes slightly large due to the influence of swelling and shape change of cellulose fibers. Moreover, the drying speed is low because rayon is difficult to dry.

In the humidifier element substrate of Example 3, the basis weight was increased, the conveyor interval was widened, and a low-density molded body was produced. These have high bending strength and shape retention, and hardly expand due to water absorption.
On the other hand, the air permeability and the water absorption speed are slightly reduced. However, since the fiber adhesion rate is high, capillary action is likely to occur, and water is sucked up relatively easily along the fiber.

  In the humidifier element base material of Comparative Example 1, since the wet heat adhesive fibers were not used, the obtained base material was very soft and did not maintain a board-like shape. Moreover, although the water absorption speed | rate was quick, the expansion | swelling by water absorption is large.

Claims (1)

A humidifier element substrate having wet heat adhesiveness and having a non-woven fiber structure, wherein the fibers are fixed by fusion of the wet heat adhesive fibers, and has a water absorption of 3 cm or more in 600 seconds (Bilec) Method), an equilibrium moisture content of 5% or less , and a substrate for a humidifier element having a swell ratio of 0.0001 to 4% when water is absorbed in a saturated state .