JP2007051398A - Liquid sucking sheet and liquid gasifying sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid sucking sheet in the form of a thin sheet having liquid sucking properties so as to rapidly raise a liquid in the width direction when a lateral edge in the width direction is brought into contact with water and stiffness suitable for folding. <P>SOLUTION: The liquid sucking sheet having a laminated structure is obtained as follows. A laminated web is prepared by arranging a second hydrophilic fiber layer composed of fibers having >20 mm fiber length and containing hydrophilic fibers on at least one surface of a first hydrophilic fiber layer composed of staple fibers having ≤20 mm fiber length and containing hydrophilic staple fibers. The resultant laminated web is placed on a support and a columnar water stream under ≥2 to ≤10 MPa pressure is jetted on both surfaces of the hydrophilic fiber web 1-5 times, respectively to mutually interlace the fibers. The first hydrophilic fiber layer and the second hydrophilic fiber layer are integrated. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid wicking sheet capable of quickly sucking up a liquid, a method for producing the same, a liquid vaporizing sheet including the sheet, and a method for vaporizing a liquid using the sheet.

  Conventionally, a sheet having a function of sucking up liquid, that is, a liquid sucking sheet is used as a vaporizing filter for a humidifier, a sucking core for sucking and volatilizing a fragrance, and a hydration sheet for agriculture and horticulture. Here, the liquid wicking sheet means that when one side of the sheet is brought into contact with the liquid, the liquid advances through the sheet along a direction perpendicular to the side by capillary action and permeates the sheet. Various nonwoven fabrics have been used as the liquid wicking sheet.

  For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2003-279084) discloses a wavy or uneven hole using a perforated nonwoven fabric having a clear opening for a filter such as a humidifier having high water uptake and low airflow resistance. It has been proposed to alternately form perforated nonwoven fabrics and planar perforated nonwoven fabrics. Patent Document 1 proposes that a perforated nonwoven fabric is formed by mixing hydrophilic fibers and hydrophobic fibers, and that the hydrophobic fibers are adhesive composite fibers. The filter described in Patent Document 1 has a low airflow resistance by being opened, and the amount of adhesive that adheres a wavy perforated nonwoven fabric and a planar perforated nonwoven fabric by using an adhesive conjugate fiber Can be reduced. Patent Document 2 (Japanese Patent Application Laid-Open No. 2005-58550) secures a gap between plant fibers by fixing an intersection portion of plant fibers with a thermoplastic resin, thereby improving the drug suction property and volatilization performance. It discloses that a structure can be obtained.

JP 2003-279084 A JP 2005-58550 A

  The humidification filter described in Patent Document 1 tends to be bulky due to the presence of pores, that is, the amount of fibers per unit volume (fiber density) tends to be small. Therefore, the suction height, that is, the suction speed is not always sufficiently high in some cases. Furthermore, when a hydrophobic fiber such as an adhesive conjugate fiber is included in the nonwoven fabric, the hydrophilicity of the entire nonwoven fabric is reduced, and thus the sucked height is further reduced. Similarly, the wicking / volatile structure described in Patent Document 2 also becomes bulky due to the gaps between the fibers, so that the wicking height does not necessarily become sufficiently large. Also, the presence of the thermoplastic resin in the structure also tends to reduce the suction height of the structure. Thus, the conventionally proposed liquid wicking sheet still has room for improvement in the liquid wicking property.

  In addition, the liquid wicking sheet may be required to exhibit a large wicking height even when its side (ie, side edge) is in contact with the liquid. However, in a sheet such as a non-woven fabric, since the constituent fibers tend to be arranged along the longitudinal direction (that is, the machine direction), the sheet tends to exhibit a high sucking property in a direction parallel to the longitudinal direction. In general, the liquid wicking property in the direction parallel to the surface is small.

  The present invention has been made in view of these circumstances, and provides a sheet having high liquid wicking property, in which the wicked liquid is uniformly diffused, and exhibits high liquid wicking property even in a direction parallel to the lateral direction. This is the issue.

  In order to solve the above problems, the present invention comprises short fibers having a fiber length of 20 mm or less, and comprises fibers having a fiber length exceeding 20 mm on at least one surface of the first hydrophilic fiber layer containing hydrophilic short fibers. A liquid wicking sheet is provided in which a second hydrophilic fiber layer containing hydrophilic fibers is disposed, and the first hydrophilic fiber layer and the second hydrophilic fiber layer are integrated by entanglement of fibers. This sheet is a nonwoven fabric in which a first hydrophilic fiber layer made of short fibers and a second hydrophilic fiber layer made of longer fibers are integrated by interlacing of fibers. Due to this feature, the sheet of the present invention is dense and has a high fiber density (amount of fibers per unit volume), a large number of capillaries are formed, and water absorption by two different fiber layers is well exhibited. Higher liquid wicking performance. Moreover, since the sheet | seat of this invention becomes a favorable formation, the liquid sucking property is shown uniformly throughout the sheet | seat. Thereby, there is little dispersion | variation in the absorbed amount of the liquid in the whole sheet | seat, and when the absorbed liquid is evaporated or volatilized, the stable performance is shown.

  Here, the term “sucking” is not only a phenomenon in which the liquid progresses upward in the sheet and is absorbed by the sheet, but also a capillary phenomenon from the contacted part when a part of the sheet comes into contact with the liquid supply source. The phenomenon that the liquid gradually proceeds in one direction in the sheet and is absorbed by the above. Therefore, for example, a phenomenon in which a part of the sheet that is in contact with the liquid supply source and horizontally disposed is advanced in one direction without being lifted and absorbed by the sheet is also included in “sucking up”.

  The first hydrophilic fiber layer is preferably a wet papermaking web or a wet nonwoven fabric before being entangled and integrated with the second hydrophilic fiber layer. By using a wet papermaking web or a wet nonwoven fabric, a denser nonwoven fabric having a high fiber density can be obtained.

  The first hydrophilic fiber layer is preferably a layer containing 30% by mass or more of cellulose short fibers as hydrophilic short fibers. Cellulose-based short fibers have excellent hydrophilicity per se, so that the first hydrophilic fiber layer can be used to increase the liquid sucking property, and the sheet is produced by the hydroentanglement method. In this case, the fiber density of the sheet is made higher by entanglement with the second hydrophilic fiber layer. The cellulosic short fibers are preferably pulp fibers.

  The present invention provides a liquid vaporization sheet comprising the liquid wicking sheet of the present invention. The liquid vaporization sheet is used to absorb the liquid and vaporize the absorbed liquid. For example, the liquid vaporization sheet is used as a vaporization filter of a humidifier. Since the liquid wicking sheet of the present invention has high strength due to the entanglement between the short fibers and the staple fibers, the liquid vaporized sheet including the liquid wicking sheet is excellent in form retention and easy to process.

  The liquid wicking sheet of the present invention has a structure in which a large number of fine capillaries are formed by entanglement of a hydrophilic fiber layer made of short fibers and another hydrophilic fiber layer made of longer fibers. high. Furthermore, in the sheet of the present invention, since the liquid is sucked up uniformly and impregnated uniformly throughout the sheet, there is also an advantage that the impregnated liquid is stably discharged from the entire sheet.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 schematically shows a cross section of the liquid wicking sheet of the present invention. The illustrated sheet is a liquid wicking sheet having a three-layer structure in which the second hydrophilic fiber layers (1, 3) are disposed on both surfaces of the first hydrophilic fiber layer (2). However, not all the portions of the sheet have a three-layer structure as illustrated. In the sheet, for example, the first hydrophilic fiber layer (2) is dropped and / or dispersed to the surroundings, so that the first hydrophilic fiber layer (2) is the second hydrophilic fiber layer (1, 3). There may be places that are not located between them.

  The liquid wicking sheet of the present invention functions to diffuse the liquid wicked by the first hydrophilic fiber layer (2), and the second hydrophilic fiber layer (1, 3) advances the liquid in one direction. It is considered that these two types of fiber layers function synergistically and exhibit excellent liquid wicking properties. More specifically, in the liquid suction sheet having this configuration, the first hydrophilic fiber layer in which short constituent fibers are randomly arranged diffuses the sucked liquid uniformly and satisfactorily. In addition, the second hydrophilic fiber layer in which the constituent fibers are long and relatively oriented in a certain direction (specifically, the longitudinal (MD) direction of the nonwoven fabric) allows the liquid to be sucked up along the certain direction. Make it easier. Furthermore, these two fiber layers are integrated by entanglement between the fibers, and in the entangled part, the fibers serve as a “bridge” that connects the layers, so that the liquid is passed through the “bridge”. By passing through, it is considered that liquid suction and diffusion are repeated alternately. Therefore, according to the liquid wicking sheet of the present invention, the liquid diffusing effect by the first hydrophilic fiber layer and the liquid wicking effect by the second hydrophilic fiber layer are exhibited synergistically, and excellent liquid wicking property is obtained. It is considered a thing. Further, in the liquid wicking sheet having this configuration, the first hydrophilic fiber layer has a uniform texture, and when one side of the sheet is brought into contact with the liquid, the liquid is wicked uniformly over the entire side. This means that in the sheet of the present invention, the liquid permeation path is not fixed to a specific path, and therefore clogging is relatively unlikely to occur in the sheet of the present invention.

The liquid wicking sheet of the present invention exhibits high liquid wicking properties even when the transverse (CD) direction of the nonwoven fabric is the liquid wicking direction. As described above, in addition to the improvement of the suction effect by alternately repeating the suction and diffusion as described above, the second hydrophilic fiber layer has a direction perpendicular to the liquid suction direction (the longitudinal (MD) direction of the nonwoven fabric). This is thought to be due to promoting the diffusion of the liquid in the parallel direction. That is, the second hydrophilic fiber layer uniformly and quickly wets the sheet in the direction perpendicular to the liquid sucking direction, and then the liquid sequentially and rapidly in the sucking direction so as to wet the portion of the sheet that has not yet been wetted. Therefore, the sheet of the present invention is considered to have good lateral liquid wicking properties.
Hereinafter, a specific configuration and the like of each fiber layer will be described.

  First, the first hydrophilic fiber layer (2) will be described. A 1st hydrophilic fiber layer (2) is a layer comprised from the short fiber whose fiber length is 20 mm or less, and including a hydrophilic short fiber. The fiber length of the fibers constituting the first hydrophilic fiber layer (2) is preferably 10 mm or less. The first hydrophilic fiber layer (2) includes hydrophilic short fibers. As hydrophilic fibers, natural fibers such as pulp, cotton, hemp, silk, and wool, regenerated fibers such as viscose rayon, cupra, and solvent-spun cellulose fibers (lyocell), and synthetic fibers were subjected to a hydrophilic treatment. A thing etc. can be used. Specifically, solvent-spun cellulose fibers are marketed under the names Lentigryocell (registered trademark) and Tencel (registered trademark). Among these, when using natural fiber, regenerated fiber, and synthetic fiber subjected to hydrophilic treatment, the fiber length is cut to 20 mm or less as necessary. The hydrophilic short fibers are preferably contained in the hydrophilic fiber layer (2) at 30% by mass or more, more preferably 50% by mass or more, and even more preferably 80% by mass or more.

  The first hydrophilic fiber layer (2) may contain fibers other than hydrophilic short fibers, for example, polyolefin fibers such as polyethylene, polypropylene, polymethylpentene, and ethylene-propylene copolymer, polyethylene terephthalate, and poly Polyester fibers such as butylene terephthalate, polyamide fibers such as nylon 6 and nylon 66, and synthetic fibers such as acrylic fibers (not hydrophilized) may be included.

  In the liquid wicking sheet of the present invention, the first hydrophilic fiber layer (2) preferably contains 30% by mass or more of pulp fibers, more preferably contains 50% by mass or more, and even more preferably contains 80% by mass or more. Preferably, it consists of pulp fibers only. The sheet containing the pulp fiber in the first hydrophilic fiber layer (2) has a high liquid absorbency, and thus exhibits a high liquid sucking property. Further, since the stiffness becomes large, it can be handled like paper, Processing becomes easy in machining. Here, “koshi” refers to the property that the liquid suction sheet is difficult to deform. Specifically, for example, when the center of a liquid suction sheet having a certain size is supported from the lower side by a pointed bar-like object, it can be said that the smaller the degree of the sheet hanging from the bar-like object, the larger the stiffness. About the liquid wicking sheet of this invention, the presence or absence of a stiffness is evaluated based on the bending resistance measured with a handle ohmmeter as mentioned later.

  As the pulp fiber, one produced by a conventional method using softwood wood or hardwood wood can be arbitrarily used. In general, the fineness of the pulp fiber is about 1.0 to 4.0 dtex and the fiber length is about 0.8 to 4.5 mm, but the pulp fiber having a fineness and / or fiber length outside this range is used. May be.

  When the first hydrophilic fiber layer (2) is composed of pulp fibers and other fibers, the other fibers are cellulosic short fibers other than pulp (for example, viscose rayon and solvent-spun cellulose fibers) or synthetic fibers. (For example, polypropylene fiber and polyester fiber).

  You may comprise a 1st hydrophilic fiber layer (2) so that 1 type, or 2 or more types of cellulosic short fibers other than a pulp fiber may be included. Here, the cellulose short fibers other than the pulp fibers are cotton and the above-mentioned regenerated fibers having a fiber length of 20 mm or less, and preferably regenerated fibers. Among these cellulosic fibers, for example, cotton has a hollow cross-section and rayon has a chrysanthemum-like cross section, so that the first hydrophilic fiber layer can be made bulky compared to a pulp having a flat cross section. It is possible to increase the function of the liquid wicking sheet to retain the liquid (liquid retention). In addition, since the regenerated fiber can be manufactured to have various finenesses, the structure of the first hydrophilic fiber layer can be changed by selecting the fineness so that the liquid wicking sheet has a desired performance. For example, since the regenerated fiber can be obtained as a fiber thinner than pulp, the first hydrophilic fiber layer can be further densified, and thereby the sucking property of the liquid sucking sheet can be further improved.

  When regenerated fibers are included in the first hydrophilic fiber layer (2), the proportion is preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 80% by mass or more, Most preferably, it is 100 mass%. When the first hydrophilic fiber layer (2) is composed of regenerated fibers and other fibers, the other fibers may be pulp fibers or synthetic fibers. The regenerated fiber contained in the first hydrophilic fiber layer (2) is preferably about 0.3 to 6 dtex, more preferably about 0.5 to 5 dtex. When the fineness of the regenerated fiber is too small, the first hydrophilic fiber layer becomes too dense and water is difficult to pass when subjected to hydroentanglement treatment, and the second hydrophilic fiber layer (1, 3) is disturbed. The surface state of the produced sheet may be deteriorated. If the fineness of the regenerated fiber is too large, there may be inconveniences such as formation of unevenness in the sheet, decrease in denseness, or insufficient entanglement between the fibers.

  In any case, the first hydrophilic fiber layer (2) before being entangled and integrated with the second hydrophilic fiber layer (1, 3) is an airlaid web or an airlaid nonwoven fabric, or a wet papermaking web or a wet nonwoven fabric. It is preferable that The air-laid web or air-laid nonwoven fabric, or the wet papermaking web or wet nonwoven fabric has a form in which the constituent fibers are relatively randomly oriented and has a uniform texture. Therefore, the first hydrophilic fiber layer formed from them absorbs This makes it easier for the liquid to diffuse. When the hydrophilic short fibers are pulp fibers, the first hydrophilic fiber layer (2) can be provided as cotton-like pulp (fluff pulp). Wet nonwovens containing or consisting of pulp fibers include paper. Paper containing or consisting of pulp fibers includes tissue (also referred to as tissue paper).

  In the present invention, the first hydrophilic fiber layer is preferably a wet papermaking web or a wet nonwoven fabric before being integrated with the second hydrophilic fiber layer. Since the wet papermaking web or wet non-woven fabric is a dense web or sheet itself, the final sheet is made dense, and a large number of fine capillaries can be formed on the sheet. The wet nonwoven fabric may be a so-called crepe paper processed into a wave shape or a wrinkle shape.

  The wet nonwoven fabric is preferably paper that consists solely of pulp fibers and is provided as tissue or pulp paper. The tissue or pulp paper may or may not have a paper strength enhancer. When tissue or pulp paper containing a paper strength enhancer is used, the stiffness of the sheet tends to be larger. However, when using a tissue or pulp paper containing a paper strength enhancer to produce a liquid wicking sheet by the hydroentanglement method, compared to using a tissue or pulp paper that does not contain it, It is necessary to increase the water pressure, which increases the manufacturing cost and the load applied to the equipment. Accordingly, the ratio (including the case of zero) of the paper strength enhancer is appropriately selected in consideration of the bending resistance of the sheet to be finally obtained, the sheet manufacturing equipment, and the like.

  Next, the second hydrophilic fiber layer (1, 3) will be described. The second hydrophilic fiber layer is composed of fibers having a fiber length exceeding 20 mm, and includes hydrophilic fibers. The second hydrophilic fiber layer preferably contains 30% by mass or more, more preferably 50% by mass or more, and even more preferably 65% by mass or more of hydrophilic fibers. Examples of hydrophilic fibers include natural fibers such as pulp, cotton, hemp, silk, and wool, recycled fibers such as viscose rayon, cupra, and solvent-spun cellulose fibers, and synthetic fibers that have been subjected to hydrophilic treatment. Can be used. One or two or more hydrophilic fibers are arbitrarily selected from these, and the second hydrophilic fiber layer is formed together with other fibers as necessary.

  In the liquid wicking sheet of the present invention, the hydrophilic fiber contained in the second hydrophilic fiber layer is particularly preferably a regenerated fiber. This is because the regenerated fiber has excellent hydrophilicity, and when the sheet is produced by a hydroentanglement method as will be described later, the regenerated fiber is well entangled with the first hydrophilic fiber layer to give a dense structure. The regenerated fiber is, for example, viscose rayon or solvent-spun cellulose fiber, and in particular, viscose rayon is preferably used because it has good entanglement and is a modified cross-section fiber that increases the water absorption rate of the sheet.

  The regenerated fiber constituting the second hydrophilic fiber layer preferably has a fineness of 0.4 to 5 dtex, and more preferably 0.7 to 3 dtex. When the fineness of the recycled fiber is small, a liquid wicking sheet having a dense structure can be obtained. However, when the fineness is less than 0.4 dtex, for example, when the second hydrophilic fiber layer is constituted by a card web, the web is constituted. It is difficult and production efficiency tends to decrease. On the other hand, if the fineness exceeds 5 dtex, the denseness of the sheet may be lowered, and the liquid wicking property may be lowered. Regenerated fibers may be used in combination of those having a small fineness and those having a large fineness, which makes it possible to efficiently produce a second hydrophilic fiber layer having a dense structure. Specifically, a recycled fiber having a fineness of about 0.5 to 2.0 dtex and a recycled fiber having a fineness of about 1.0 to 5.0 dtex are mixed at a ratio of 3: 7 to 7: 3 (mass ratio). Are preferably used.

  Before the second hydrophilic fiber layer is entangled and integrated with the first hydrophilic fiber layer (2), card webs such as parallel web, cross web, semi-random web, and random web, and long fiber web and long fiber It takes the form selected from a nonwoven fabric etc. In the sheet of the illustrated form, each of the second hydrophilic fiber layers (1, 3) may be a laminate of two or more webs. Alternatively, one of the two second hydrophilic fiber layers may be a laminate of two or more webs, and the other may be a single layer web.

  The second hydrophilic fiber layer is preferably formed of a card web. When the card web is used, the entanglement with the first hydrophilic fiber layer becomes good. If the confounding property between the first hydrophilic fiber layer and the second hydrophilic fiber layer is poor, it may be difficult to obtain the water absorption characteristics of both fiber layers synergistically. Further, the card web can be easily formed by mixing two or more kinds of fibers, and gives a form in which two or more kinds of fibers are uniformly mixed in the obtained web. Therefore, when a card web is used, it becomes easy to obtain a sheet having desired physical properties by adjusting the kinds and ratios of two or more kinds of fibers according to the use and purpose.

  When the second hydrophilic fiber layer is constituted by a card web, the fibers constituting the fiber layer are preferably staple fibers having a fiber length of more than 20 mm and not more than 110 mm. The fiber length of the staple fiber is more preferably more than 20 mm and not more than 80 mm, and still more preferably not less than 30 mm and not more than 70 mm. If the fiber length of the staple fibers is less than 20 mm, the fibers are often dropped and the processability is also inferior. When the fiber length of the staple fiber exceeds 110 mm, the entanglement due to the high-pressure water flow treatment is lowered.

  When the second hydrophilic fiber layer includes fibers other than the hydrophilic fibers, the other fibers may include, for example, the synthetic fibers described in relation to the first hydrophilic fiber layer. For example, the other fibers may be polyester fibers such as polyethylene terephthalate (PET) fibers. When the second hydrophilic fiber layer contains polyester fiber, the second hydrophilic fiber layer becomes bulky. For example, when sucking up a liquid containing a solid content or a component that becomes solid due to change over time, Clogging is less likely to occur. However, it should be noted that when the proportion of the synthetic fiber in the second hydrophilic fiber layer is large, the hydrophilicity is lowered and the sucking height is reduced. Therefore, the ratio of the synthetic fiber contained in the second hydrophilic fiber layer needs to be less than 70% by mass, preferably about 20 to 50% by mass, and preferably about 20 to 35% by mass. More preferred.

  The basis weight of the first hydrophilic fiber layer (2) and the second hydrophilic fiber layer (1, 3) is appropriately selected according to the desired basis weight of the sheet and the stiffness (flexibility) to be applied to the sheet. Generally, the larger the basis weight of the first hydrophilic fiber layer (2), the greater the stiffness of the sheet. Specifically, the basis weight of the first hydrophilic fiber layer (2) is preferably selected so as not to exceed 70% by mass, more preferably not to exceed 60% by mass, based on the total weight of the sheet. And most preferably selected to be 10-50% by weight. When the proportion of the first hydrophilic fiber layer (2) exceeds 70% by mass (that is, the proportion of the second hydrophilic fiber layer (1, 3) is 30% by mass or less), hydroentanglement When producing a sheet by the method, the water flow may not easily penetrate, and as a result, the sheet strength may be reduced. On the other hand, when the proportion of the first hydrophilic fiber layer (2) is small (that is, when the proportion of the second hydrophilic fiber layer (1, 3) is large), the stiffness of the sheet is small and the denseness is high. A liquid wicking sheet may not be obtained, and a desired liquid wicking property may not be obtained.

Liquid wicking sheet of the present invention, the basis weight of the entire sheet with 50 to 400 g / ^{m 2} approximately, the basis weight of the first hydrophilic fiber layer (2), it is preferable that a 10 to 100 g / ^{m 2} approximately, the second The basis weight of the hydrophilic fiber layer (1, 3) is preferably about 10 to ²⁰⁰ g / m ² , respectively. If the basis weight of the entire sheet is less than 50 g / m ² , the stiffness of the entire sheet may be reduced. If the stiffness of the sheet is small, the form retainability may be poor, and the moldability may deteriorate.For example, when the sheet tip is used in contact with liquid, the sheet tip is difficult to stay along the liquid bottom or stays. It becomes difficult. In addition, if the basis weight is small, the amount of liquid held in the liquid wicking sheet is reduced, and volatility may be reduced when the wicked liquid is used to volatilize. Furthermore, when using a sheet with a small basis weight, for example, as a wicking core for a fragrance, clogging may occur in the sheet when the components contained in the fragrance are deposited as solids over time. . When the basis weight of the entire sheet exceeds 400 g / m ² , handling becomes difficult and the cost may increase. More preferably, the basis weight of the entire sheet is about 70 to 300 g / m ² , the basis weight of the first hydrophilic fiber layer (2) is about 10 to 60 g / m ² , and the second hydrophilic fiber layer (1, The basis weight of 3) is about 10 to 150 g / m ² , respectively. The basis weight of the sheet is selected according to the application within the above-described range. For example, when the sheet is used as a vaporization filter used in a humidifier, the basis weight of the entire sheet is about 50 to 150 g / m ² and the basis weight of the first hydrophilic fiber layer (2) is about 10 to 60 g / m ^2. The basis weight of the second hydrophilic fiber layer (1, 3) is preferably about ²⁰ to 70 g / m ² . More preferably, the basis weight of the vaporization filter sheet is about 60 to 100 g / m ² , the basis weight of the first hydrophilic fiber layer (2) is about 10 to 50 g / m ² , and the second hydrophilic fiber layer ( 1,3) is about 25 to 35 g / m ² .

  In any application, the basis weights of the first hydrophilic fiber layer (1) and the second hydrophilic fiber layer (3) may be the same or different from each other. For example, one basis weight may be about 2 to 3 times the other basis weight.

  The liquid wicking sheet of the present invention has a configuration in which fibers are entangled by hydroentanglement treatment and the first hydrophilic fiber layer (2) and the second hydrophilic fiber layer (1, 3) are integrated. preferable. According to the hydroentanglement treatment, the short fibers and the hydrophilic fibers are entangled satisfactorily, and a denser liquid wicking sheet can be obtained. Moreover, the liquid wicking sheet formed by entanglement of fibers by the hydroentanglement process has a high fiber density and can be provided in a relatively thin form. Therefore, when such a liquid suction sheet is used as, for example, a vaporization filter of a humidifier, it can be stored in a predetermined space, and therefore, combined with the high water absorption of the sheet itself. Thus, more water can be sucked up uniformly and more water vapor can be supplied stably. Similarly, when the liquid wicking sheet of the present invention is used as a wick for fragrance products, more fragrance can be quickly and uniformly permeated throughout the sheet, and can be volatilized uniformly from the entire sheet. Become.

  Alternatively, the liquid wicking sheet of the present invention may have a configuration in which the fibers are entangled by needle punching and the first hydrophilic fiber layer and the second hydrophilic fiber layer are integrated. Such a configuration is employed particularly when the basis weight of the liquid suction sheet is large. Or you may comprise a liquid wicking sheet | seat combining a needle punch process and a hydroentanglement process.

  The liquid wicking sheet of the present invention can be used as, for example, a liquid vaporization sheet, and is preferably used as a vaporization filter such as a sheet for sucking and volatilizing a fragrance or an insect repellent and a humidifier as described above. Since the sheet of the present invention has a firmness and good shape retention, it can be easily processed into various shapes. For example, when contacting with liquid in a container, the liquid bottom (the bottom of the container) ) Is easy to follow.

  Specifically, when the liquid suction sheet of the present invention is used as a vaporization filter such as a humidifier or a sheet for volatilizing fragrance or insect repellent, the bending resistance of the sheet measured with a handle ohmmeter is longitudinal (MD ) Direction (the machine arrangement direction of the nonwoven fabric production line (the traveling direction of the nonwoven fabric)) is preferably 40 g or more. The bending resistance measured by the handle ohmmeter is an index indicating the stiffness (or rigidity) of the seat. When the bending resistance is smaller than the above preferred lower limit in the longitudinal direction, the sheet is not stiff and difficult to handle, and the formability and shape retention of the sheet may be inferior.

  In addition, the liquid wicking sheet of the present invention preferably has a wicking height in the horizontal direction of 100 mm / 5 minutes or more, more preferably 110 mm / 5 minutes or more as measured by the birec method. The sheet of the present invention has a high liquid sucking property even in a direction parallel to the lateral direction due to its dense structure, and can be configured to have such a sucking height. When the lateral suction height is less than 100 mm / 5 minutes, as described above, when the side edge is used in contact with the liquid, it takes time until the sheet gets wet. When using as, the time from the start of use until a sufficient amount of liquid is volatilized may become longer.

  The bending resistance and the suction height shown above indicate one preferable form of the vaporization filter. The sheet having such bending resistance and sucking height may be formed into a pleated shape or a honeycomb shape and used as a vaporization filter. Since the liquid wicking sheet of the present invention has high liquid wicking property and stiffness in any direction, for example, when used in a folded state, the fold line can be parallel to both the longitudinal and lateral directions of the nonwoven fabric. it can. The vaporization filter comprising the liquid wicking sheet of the present invention may be configured such that the bending resistance and the wicking height in the lateral direction are out of the above ranges, depending on the specifications of the humidifier and the folding form. Further, when the liquid wicking sheet of the present invention is used for applications other than the vaporization filter of the humidifier, the bending resistance may be smaller than the lower limit of the above range, or the lateral wicking height may be smaller than the lower limit of the above range. It's okay.

  Next, the preferable manufacturing method of the liquid wicking sheet of this invention is demonstrated. In order to manufacture the illustrated sheet, first, a laminated web in which a fiber web or a non-woven fabric serving as a first hydrophilic fiber layer is positioned between fiber webs serving as a second hydrophilic fiber layer is prepared. The laminated web is prepared by laminating webs in the order of a fiber web to be the second hydrophilic fiber layer-a fiber web to be the first hydrophilic fiber or a nonwoven web to a fiber web to be the second hydrophilic fiber layer. As described above, the fiber web or nonwoven fabric to be the first hydrophilic fiber layer is a wet papermaking web, a wet nonwoven fabric prepared in advance, or an airlaid web. When the first hydrophilic fiber layer is formed of pulp fibers, the pulp fiber layer may be produced by spreading fluff pulp on the hydrophilic fiber web.

  The fiber web to be the second hydrophilic fiber layer may be in any form selected from a parallel web, a card web such as a cross web, a semi-random web and a random web, and a long fiber web. The hydrophilic fiber web is preferably a card web. This is because the card web has a high strength and an appropriate fiber density (interfiber spacing).

The hydroentanglement treatment conditions for the laminated web are appropriately set according to the basis weight of the laminated web and the desired mechanical strength of the obtained sheet. For example, hydroentanglement treatment of a laminated web having a basis weight of 50 to 100 g / m ² is performed by placing the web on a plain weave support of 80 to 100 mesh, and the orifice having a pore diameter of 0.05 mm or more and 0.5 mm or less is 0. It may be carried out by spraying a water flow with a water pressure of 2 MPa or more and 10 MPa or less on the front and back surfaces of the laminated web 1 to 5 times from a nozzle provided at intervals of 3 mm or more and 1.5 mm or less. The water pressure is preferably 2 MPa or more and 8 MPa or less, more preferably 3 MPa or more and 7 MPa or less. When the laminated web has a two-layer structure composed of a first hydrophilic fiber layer and one second hydrophilic fiber layer, the water flow is jetted only to the second hydrophilic fiber layer side.

  In the hydroentanglement process, a water flow having a water pressure in the above range is sprayed once on one surface of the laminated web from a nozzle in which orifices having a hole diameter of 0.08 mm to 0.2 mm are provided at intervals of 3 mm to 15 mm. Further may be included. As a result, it is possible to obtain a sheet in which the thin portions where the fibers are more closely entangled are formed in a stripe shape corresponding to the interval between the orifices.

  After the high-pressure water treatment, the resulting laminated nonwoven fabric is dried to remove moisture. The drying temperature is selected according to the type and basis weight of the fibers constituting the sheet. For example, when the first hydrophilic fiber layer has a laminated structure including pulp fibers and the second hydrophilic fiber layer includes regenerated fibers, the drying temperature is preferably set to 100 to 150 ° C., more preferably 120 to Set to 140 ° C.

  The liquid wicking sheet of the present invention thus obtained has a high strength and a firmness because fibers are intertwined closely by hydroentanglement. Therefore, this sheet can be practically used without bonding the fibers with a binder or a heat-bonding fiber. Since binders or heat-bondable fibers are generally hydrophobic and reduce liquid wicking properties, by not using it, liquid wicking sheets will exhibit higher liquid wicking properties.

  The liquid wicking sheet of the present invention is used after being cut to an appropriate size according to the application. Further, a plurality of sheets may be used in a stacked manner depending on the application.

  The liquid wicking sheet of the present invention has a feature that the wicking height in the lateral direction is large, so that one side of the side (that is, the end in the width direction) is brought into contact with the liquid in a direction parallel to the width direction, You may use so that a liquid may advance in a sheet | seat toward the edge | side facing the said edge from the said edge | side. Alternatively, it is naturally possible to use the sheet by bringing one side parallel to the width direction (one side perpendicular to the longitudinal direction of the sheet) into contact with the liquid. The sheet brought into contact with the liquid is used as a liquid-impregnated sheet in an independent form that releases the contact with the liquid after the liquid has progressed and penetrated into all or part of the sheet and uses the liquid that has penetrated into the sheet. May be. The liquid that has advanced into the sheet may be volatilized by ventilation, heating, or natural evaporation. The liquid is, for example, water or water containing an antibacterial agent or preservative, a fragrance, a deodorant, an insect repellent, an insecticide, or a liquid fertilizer.

  In the above description, the liquid wicking sheet having a three-layer structure has been mainly described. However, the sheet of the present invention may have a two-layer structure including a first hydrophilic fiber layer and one second hydrophilic fiber layer. . In this case, the preferred basis weight of each layer is appropriately determined in consideration of the ratio of the first hydrophilic fiber layer to the entire sheet as described above in connection with the nonwoven fabric having a three-layer structure. Alternatively, the liquid wicking sheet of the present invention may have a form in which two or more first hydrophilic fiber layers and two or more second hydrophilic fiber layers are laminated. In this case, the preferred basis weight of each layer is appropriately determined in consideration of the ratio of the two or more first hydrophilic fiber layers in the entire sheet, as described above in connection with the nonwoven fabric having a three-layer structure. Is done.

Hereinafter, the contents of the present invention will be described with reference to examples.
[Sample 1]
As a nonwoven fabric to be the first hydrophilic fiber layer, a tissue (manufactured by Omiya Paper Co., Ltd.) having a basis weight of 12 g / m ² composed of 100% by mass of pulp fibers was prepared. On the other hand, as the second hydrophilic fiber layer, a fiber web of viscose rayon (manufactured by Daiwabo Rayon Co., Ltd.) having a fineness of 1.7 dtex and a fiber length of 40 mm and polyethylene terephthalate fiber having a fineness of 1.45 dtex and a fiber length of 38 mm (product) Name: RA02F, manufactured by Teijin Ltd.) was mixed at a ratio of 7: 3 (mass ratio) to prepare a parallel card web. Lamination was performed such that a fiber web to be the second hydrophilic fiber layer was disposed on both surfaces of the tissue, and hydroentanglement treatment was performed on the laminated web. In the hydroentanglement treatment, a columnar water flow having a water pressure of 2 MPa is jetted twice on one surface of a web using a nozzle having orifices with a pore diameter of 0.12 mm provided at intervals of 0.6 mm, and a columnar water flow having a water pressure of 3 MPa is applied to the other surface. Was injected once. The jet of columnar water flow was carried out by placing the web on a 90 mesh plain weave support and transporting it at a speed of 4 m / min. After the hydroentanglement treatment, drying was performed at 135 ° C. to obtain a liquid wicking sheet.

[Samples 2 to 10]
Using the fibers and hydroentanglement treatment conditions shown in Table 1, a liquid wicking sheet was produced according to the same procedure as that adopted when producing Sample 1. In the table, the meaning of each symbol is as follows.

First hydrophilic fiber layer (non-integrated nonwoven fabric or web constituent fibers and basis weight, etc.)
T12 Pulp fiber 100% by weight, tissue with a basis weight of 12 g / m ² Omiya Paper Co., Ltd. T24-a Pulp fiber 100% by weight, tissue with a basis weight of 24 g / m ² ,
Made by adding 0.6% of paper strength enhancer to the slurry before wet papermaking
Matsuoka Paper Co., Ltd. T24-b 100% by mass of pulp fiber, tissue with a basis weight of 24 g / m ² ,
Made by adding 0.2% paper strength enhancer to the slurry before wet papermaking
Matsuoka Paper Co., Ltd. T24-c 100% by mass of pulp fiber, tissue with a basis weight of 24 g / m ² ,
Zero use of paper strength enhancer
T24-2ply made by Matsuoka Paper Co., Ltd. 100% by mass of pulp fiber, 2ply product of tissue with a basis weight of 12g / m ²
T-17 manufactured by Omiya Paper Co., Ltd. Tissue with 100% by mass pulp fiber and a basis weight of 17 g / m ²
T-19, manufactured by Havicks Co., Ltd. Tissue with 100% by mass pulp fiber and a basis weight of 17 g / m ²
Made by Crecia

Second hydrophilic fiber layer R1 Viscose rayon with a fineness of 1.7 dtex, fiber length 40 mm R2 fineness 0.9 dtex made by Daiwabo Rayon Co., Ltd. Viscose rayon with a fiber length 38 mm PET fineness 1.45 dtex made by Daiwabo Rayon Co., Ltd. Polyethylene terephthalate fiber with a fiber length of 38 mm Made by Teijin Limited

[Sample 11]
As a nonwoven fabric to be the first hydrophilic fiber layer, a tissue having a basis weight of 17 g / m ² consisting of 100% by mass of pulp fibers (manufactured by Habicks Co., Ltd.) was prepared. On the other hand, viscose rayon (manufactured by Daiwabo Rayon Co., Ltd.) having a fineness of 0.9 dtex and a fiber length of 38 mm and a viscose rayon having a fineness of 1.7 dtex and a fiber length of 40 mm (Daiwabow) are used as the second hydrophilic fiber layer. A parallel card web was prepared in which Rayon Co., Ltd.) was mixed at a ratio of 7: 3 (mass ratio). Lamination was performed such that the webs to be the second hydrophilic fiber layers were disposed on both sides of the tissue, and hydroentanglement treatment was performed on the laminated webs. In the hydroentanglement treatment, a columnar water flow having a water pressure of 2 MPa is jetted once on one surface of a web using a nozzle having pores of 0.12 mm provided at intervals of 0.6 mm, and the same nozzle is used on the other surface. After the columnar water flow having a water pressure of 3 MPa was jetted once, the columnar water flow having a water pressure of 5 MPa was jetted once by using a nozzle in which orifices having a hole diameter of 0.13 mm were provided at intervals of 7 mm on the other surface. The jet of columnar water flow was carried out by placing the web on a 90 mesh plain weave support and transporting it at a speed of 4 m / min. After the hydroentanglement treatment, drying was performed at 135 ° C. to obtain a liquid wicking sheet. In this sheet, portions with a small thickness were formed in stripes at intervals of about 7 mm.

[Samples 12 and 13]
Using the fibers and hydroentanglement treatment conditions shown in Table 1, a liquid wicking sheet was produced according to the same procedure as that adopted for the preparation of Sample 11.

[Sample 14]
Using only the viscose rayon used in the manufacture of Sample 1, a parallel card web having a basis weight of about 70 g / m ² is prepared, and this is subjected to hydroentanglement treatment under the same conditions as those used in the preparation of Sample 1. To obtain a sheet.
[Sample 15]
Using the viscose rayon and PET fiber used in the manufacture of sample 1, a parallel card web having a basis weight of about 70 g / m ² is prepared, and this is hydroentangled under the same conditions as those used in the preparation of sample 1. The sheet was obtained by processing.

[Sample 16]
Ratio of PET fiber (manufactured by Teijin Ltd.) with a fineness of 1.5 dtex and fiber length of 45 mm to viscose rayon (manufactured by Daiwabo Rayon Co., Ltd.) with a fineness of 1.7 dtex and fiber length of 7: 3 (mass ratio) A parallel card web mixed in the above was prepared. The webs were laminated so that parallel webs made only of viscose rayon used in the manufacture of Sample 1 were disposed on both sides of the webs, and hydroentangled with the laminated webs. The conditions of the hydroentanglement process are as shown in Table 1.

[Samples 17 to 23]
The tissue used to make Samples 1-13 was prepared to evaluate its own liquid uptake.

  About the obtained sample, the siphoning height by the birec method and the bending resistance was evaluated according to the following procedure. The evaluation results are shown in Tables 2-4.

[Suction height]
According to JIS L 1096 6.26.1 B method, for samples 1 to 21, the sample was set so that the water suction direction coincided with the horizontal direction, and the suction height was measured. For 8 and 10, the sample was set so that the suction direction coincided with the longitudinal direction, and the suction height was measured. The wicking height was measured every 30 seconds for some samples, and the wicking height after 5 minutes was measured for all samples.

[Bending softness]
Measurement was performed using a handle ohmmeter (model HOM-200, manufactured by Daiei Kagaku Seiki Seisakusho). More specifically, a test piece having a length × width of 20 × 17.5 cm was set on a slit having a width of 10 mm so as to be perpendicular to the slit, and 6.7 cm (1 of the test width) from the side of the test piece. / 3) was pushed 8 mm with a penetrator blade, and the resistance value at this time was evaluated as the bending resistance. Here, for samples 1 to 3, 7, 8 and 10, only the bending resistance in the vertical direction was measured. The bending resistance shown in Table 4 is an average value of measured bending resistance for each of the front and back surfaces of one sample.

  From the results shown in Tables 2 and 3, Samples 1 to 13, which are sheets having a three-layer structure with a tissue as an intermediate layer, have a suction height in the longitudinal direction and / or the lateral direction of more than 100 mm in 5 minutes, and have a liquid suction property. Is high. More specifically, it can be seen from the comparison between Samples 1 to 4 and Sample 15 that even when the second hydrophilic fiber layer contains synthetic fibers, excellent wicking properties are exhibited when combined with tissue. Moreover, it can be seen from the comparison between the sample 14 made only of the rayon fiber layer and the samples 5 to 11 and 13 that a higher suction property can be obtained by combining the hydrophilic layer made only of the rayon fiber with the tissue. In Sample 16, the middle layer was formed of staple fibers, and the suction height was small compared to Samples 1-11. This also indicates that the formation of the layer containing hydrophilic short fibers contributes to the improvement of the liquid sucking property of the sheet.

  Further, during the measurement of the sucked height, water was not sucked up uniformly in the samples 14 and 15, and a difference occurred in the sucked height. The numerical values for these samples in the table correspond to the height of the highest position of the water drawn up. On the other hand, in Samples 1 to 13, water rises more uniformly than Samples 14 and 15, and in Samples 5 to 11 and 13 in which the hydrophilic layer is composed only of viscose rayon, it is in contact with water. The water rose more uniformly over the entire side. In addition, when comparing the samples 1 and 2, the samples 3 and 4, and the samples 7 and 10 with respect to the suction height in the longitudinal direction in particular, when the constituent fibers of the second hydrophilic fiber layer are the same, It was found that the higher the basis weight, the greater the suction height.

  By comparing Samples 1 and 3, Samples 2 and 4, and Samples 5 and 6, it can be seen that when the second hydrophilic fiber layer contains viscose rayon having a small fineness, the sucking performance is further improved. Moreover, it can be seen from the comparison of the vertical suction heights of Samples 1 and 2 and Samples 7 and 10 that the higher the tissue weight, the higher the suction performance.

  Samples 7, 8, and 9 having different contents of the paper strength enhancer in the tissue showed the same level of liquid uptake, but the water pressure during the hydroentanglement treatment was lowest in Sample 9. From this, it can be said that the tissue pulp fiber that does not use the paper strength enhancer is more likely to be entangled with the hydrophilic fiber than the tissue pulp fiber containing the paper strength enhancer.

  The bending resistance of Sample 7 was the largest among the measured samples. Further, the bending resistance of the sample 7 was significantly different from that of the sample 8 (second largest). From this, it was found that the stiffness of the entire sheet can be increased by using a tissue containing a paper strength enhancer. Therefore, the sample 7 is particularly preferable as a vaporizing filter for a humidifier because it has a high stiffness and a high sucking property.

  Furthermore, it was found from the comparison of the bending resistance between Sample 1 and Sample 2 that the bending resistance tends to increase as the tissue weight increases. This is thought to be due to the fact that the tissue itself is a dense structure. Moreover, it was found from the comparison of the bending resistance between Sample 1 and Sample 3 that the bending resistance tends to increase as the fibers constituting the second hydrophilic fiber layer become thinner. This is considered to be because as the fibers of the second hydrophilic fiber layer are thinner, the entanglement between the fibers and the pulp fibers becomes closer.

  The liquid wicking sheet of the present invention comprises a first hydrophilic fiber layer comprising a short fiber having a fiber length of 20 mm or less and comprising a hydrophilic short fiber and a fiber having a fiber length exceeding 20 mm and comprising a hydrophilic fiber. By combining with 2 hydrophilic fiber layers, it is excellent in the liquid sucking property, and it can be configured as having a stiffness by forming the first hydrophilic fiber layer with a wet nonwoven fabric. Therefore, the liquid wicking sheet of the present invention is preferably used as a vaporization filter for a humidifier that needs to be folded, or is preferably used as a water retention sheet for aromatic products or agriculture / horticulture.

It is sectional drawing which shows typically one form of the liquid wicking sheet | seat of this invention.

Explanation of symbols

1, 3 Second hydrophilic fiber layer 2 First hydrophilic fiber layer

Claims (6)

  A second hydrophilic fiber comprising a short fiber having a fiber length of 20 mm or less and comprising a fiber having a fiber length of more than 20 mm on at least one surface of the first hydrophilic fiber layer comprising the hydrophilic short fiber and comprising the hydrophilic fiber. A liquid wicking sheet in which layers are disposed and the first hydrophilic fiber layer and the second hydrophilic fiber layer are integrated by interlacing of fibers.   The liquid wicking sheet according to claim 1, which is a wet papermaking web or a wet nonwoven fabric before the first hydrophilic fiber layer is integrated with the second hydrophilic fiber layer.   The liquid wicking sheet according to claim 1 or 2, wherein the first hydrophilic fiber layer contains 30% by mass or more of cellulose-based short fibers as hydrophilic short fibers.   The liquid wicking sheet according to claim 3, wherein the cellulosic short fibers are pulp fibers.   The liquid wicking sheet according to any one of claims 1 to 4, wherein the second hydrophilic fiber layer is a card web containing 30% by mass or more of recycled fibers as hydrophilic fibers. The liquid vaporization sheet | seat which comprises the liquid wicking sheet of any one of Claims 1-5.

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