JP2006159538A - Water absorbent material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water absorbent material which simplifies a process at the time of processing of a product, imparts a good wearing feeling to the product, has no wetting feeling, causes no leakage of moisture and has excellent washing durability. <P>SOLUTION: The water absorbent material is composed of at least a water absorbent layer and a waterproof layer both of which are integrally fixed over the almost whole surfaces of them. The water absorbent layer comprises fibers and has a gap quantity per 100 cm<SP>2</SP>of 10 cc or above and a thickness of 1-20 mm. The main constituent fiber is a synthetic fiber with a thickness of 0.01-2 dtex and the waterproof layer is constituted of a synthetic resin film. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a water-absorbing material composed of at least a fiber and a synthetic resin film, water-absorbing, and water-absorbing and preventing water from seeping out, that is, a water-absorbing material excellent in waterproofness. The present invention relates to a water-absorbing material suitable for use in sanitary sheets, clothes, miscellaneous goods, and bedding.

  Patent Document 1 discloses a waterproof material in which a long-fiber spunbond nonwoven fabric and a wood pulp fiber sheet are laminated and a synthetic resin film is laminated on a nonwoven fabric subjected to high-pressure water column flow treatment. This composite nonwoven fabric sheet is intended to be waterproof and does not have a water absorption function. In addition, when used in sheets, diapers, etc., the waterproof material and the water absorbing material are independent of each other, so that the feeling of wear is poor, such as slippage between the fabrics when worn.

  Patent Document 2 discloses a waterproof sheet having a three-layer structure using a water permeable / diffusion fabric for the outer surface, a non-woven fabric with a water repellent finish for the intermediate layer, and a fabric with a water repellent finish for the backing. Although this waterproof sheet is excellent in surface wetting and moisture permeability, the woven or knitted fabric as the lining may be difficult to satisfy the liquid impermeability due to the stretch and external pressure of the fabric during actual use.

Patent Document 3 discloses a water-absorbing material obtained by sewing each independent fabric, but when the fabrics are laminated and sewn, it is difficult to sew and lacks handleability.
Japanese Patent Application Laid-Open No. 08-141313 JP 2001-046203 A JP 2003-342862 A

    The present invention is intended to solve these conventional problems and provide a water-absorbing material excellent in moisture absorption, wettability, waterproofness, industrial washing resistance, processability, and product appearance.

The present invention employs the following means in order to solve such problems. That is,
(1) A water-absorbing material composed of at least a water-absorbing layer and a waterproof layer, and both layers are integrally fixed over almost the entire surface, the water-absorbing layer is composed of fibers, and the amount of voids per 100 cm ² is 10 cc or more. The water-absorbing material is characterized in that the fibers constituting the water-absorbing layer with a thickness of 1 mm to 20 mm are mainly synthetic fibers with a thickness of 0.01 to 2 dtex, and the waterproof layer is a synthetic resin film,
(2) The water-absorbing material, wherein a water-absorbing agent is applied to the fibers constituting the water-absorbing layer,
(3) The water-absorbing material according to any one of the above, wherein the fibers constituting the water-absorbing layer have antibacterial properties,
(4) The water-absorbing material according to any one of the above-mentioned, wherein the water-absorbing layer is formed by laminating a plurality of layers of the same type.
(5) The water-absorbing material according to any one of the above, wherein the waterproof layer has a water pressure resistance of 50 kpa or more.
(6) The water-absorbing material according to any one of the above, wherein the synthetic resin film constituting the waterproof layer is a polyurethane film,
(7) On the surface of the water-absorbing layer, a fabric having characteristics different from those of the water-absorbing layer is located. The fabric is provided with a water-absorbing agent and has an air permeability of 100 cc / cm ² / sec or more. Any one of the above water-absorbing materials, wherein the layer and the fabric are fixed together in whole or in part,
(8) The water absorbent material according to any one of 1 to 7 above, wherein the water absorbent material is for bedding or a cover for bedding,
(9) The water-absorbing material according to any one of 1 to 7 above, which is for excretion care wearing materials such as diapers and incontinence pants,
(10) The water absorbing material according to any one of 1 to 7 above, which is used for a foot cleaning mat;
(11) Bedding such as bedding or a bedding cover using the water absorbing material according to any one of 1 to 7 above.
(12) An excretion care wearing material using the water absorbing material according to any one of 1 to 7 above.
(13) A foot-wiping mat using the water absorbing material according to any one of 1 to 7 above.

  According to the present invention, it is possible to reduce the number of cutting and sewing processes in manufacturing, and to accurately manufacture. The finished product is bulky and can be made slim with no bumps. Fits to the body even when worn, can be used slim, there is no feeling of wetness, no leakage, and there is little change in shape even after repeated washing.

The water absorbing material of the present invention comprises at least a water absorbing layer and a waterproof layer.
The water absorption layer is composed of a fabric made of fibers.

  The fabric refers to a sheet shape such as a nonwoven fabric, a woven fabric, and a knitted fabric, and any fabric that exhibits these forms can be used. Of these, non-woven fabric is preferable because it can be easily changed in thickness, void amount, etc., and is advantageous in price.

  Such a fabric is composed of fibers and voids, but in order to improve water absorption, it is desirable to increase the surface area of the voids and single fibers to retain moisture by capillary action.

The water absorption layer is required to have a void amount of 10 cc / 100 cm ² or more. The void amount is indicated by a value obtained by subtracting the volume occupied by the fiber from the volume of the fabric. That is, this amount is the amount of moisture absorbed, and the more the better.

Empirically, if it is less than 10 cc / 100 cm ² , the amount of voids is small and the amount of water that can be absorbed is small, and the saturated state is immediately reached.
For example, when diaper is used, the amount of urine per one time is 150 cc to 200 cc, and the maximum void amount corresponding to two or more times is 500 cc / 100 cm ^2, which is effective enough. Too much capillarity disappears, and when pressed, the amount of compression is large, which may push out the contained moisture, which may be undesirable.

The void amount of the fabric-like water-absorbing material is expressed by the following formula: void amount of fabric = volume of fabric−volume of fibers constituting the fabric.

The fabric volume is 5 cm or more in thickness with a pile of cloth-like water absorbent material, and the size is 10 cm or more in length and width, and after pre-compression by applying a load of 10 g / cm ^{2 to} remove excess voids such as wrinkles. , Applying a load of 0.5 g / cm ² , measuring the thickness and the size of the vertical and horizontal, and calculating. The volume of the fibers constituting the fabric is calculated from the specific gravity of the used fibers by measuring the weight and volume of the fabric.

  The thickness of the water-absorbing layer is preferably as thin as possible from the viewpoint of handleability, but is preferably as thick as possible from the viewpoint of the amount of voids. The thickness may be at least 0.5 mm, preferably 1 mm or more and up to 20 mm. If the thickness is 0.5 mm or less, the amount of voids is small, so the amount of water absorption is small, and it may be difficult to use depending on the application. On the other hand, if it is 20 mm or more, the amount of voids is large and the amount of water absorption increases, but it cannot be used from the viewpoint of handling, discomfort when worn, and price. Most preferred is 3 to 15 mm.

  The density of the water absorbing layer is preferably in the range of 0.07 to 0.5 g / cm3. When the amount is less than 0.07 g / cm 3, the amount of voids increases, but moisture retention due to capillary action and the exudation of moisture when pressed due to an increase in compression rate are undesirable. On the other hand, when the amount is 0.5 g / cm 3 or more, the fiber occupying space is large, the water holding amount is small, and the material is heavy, hard, and tends to use much material. The most preferable range is 0.1 to 0.4 g / cm 3.

  It is necessary that the water absorption layer is mainly composed of synthetic fibers. When a large amount of natural fiber is contained, the fiber itself absorbs water, resulting in a feeling of wetting in the fiber itself.

  As the synthetic fiber, any of polyester, polyamide, acrylic, polypropylene, polyethylene and the like can be used.

The thickness of the fiber is important, and the thinner one is preferable because the surface area of the fiber is increased and the space generated between the fibers is reduced, so that capillary action can be effectively used and moisture retention is improved. 0.01 dtex to 2 dtex can be used, and if it is thinner than this, moisture retention is too high, and the washing and drying properties tend to deteriorate. Moreover, since the rigidity of the single fiber is small, there arises a problem that the retainability of the void is deteriorated in the change in the shape of the water absorption layer. Since the thickness of 2 dtex or more is too thick, the space where the fibers are formed becomes large and the moisture retention is worsened. At the same time, the moisture tends to move during use and the moisture oozes out.

In the present invention, the water absorbing layer may be used as a single layer, but is preferably composed of a plurality of layers. As a plurality of layers, the same kind of layers may be superposed, or layers having different fiber thicknesses may be combined. It is preferable that the water-absorbing layer is composed of a plurality of layers because the number of laminated layers can be adjusted according to the amount of water absorption required for the product water-absorbing material, and the desired amount of water absorption can be easily accommodated. Further, by overlapping a plurality of layers, bending occurs because of a displacement between the layers with respect to bending deformation. Moreover, in order to obtain a dry feeling at the time of water absorption, it is preferable that the surface layer of the water absorption layer is composed of thick fibers and the back layer is composed of thin fibers. In such a configuration, when water is absorbed, moisture quickly passes through a layer composed of thick fibers and is absorbed by a layer composed of thin fibers having a large single fiber surface area per mass.

  As a method for bonding a plurality of layers, any of the bonding methods such as first stacking layers and bonding by needle punching, water punching, and bonding with an adhesive can be used.

  The cross section of the fiber that can be used can be any cross section such as solid, hollow, T-shaped, flat, and teardrop-shaped. In particular, a fiber having a large surface area is preferable, and a complicated cross section such as a T-type, Y-type, H-type, π-type, or tear-type is particularly preferable because it retains moisture.

  The structure of the fibers constituting the water-absorbing layer may be any of a nonwoven fabric, a woven fabric, a knitted fabric, etc., but a nonwoven fabric is preferable in order to obtain price, ease of handling, and uniform void amount. Bonding of the fibers for obtaining the nonwoven fabric may be any method such as needle punching, water punching, heat setting, and adhesive. As a means for obtaining a fiber having a fineness of 1 dtex or less, any one of melt blown, spunbond, fiber obtained by elution of a sea part using sea-island fiber, fiber obtained by dividing composite fiber by high-pressure water flow, etc. Can be used.

  A non-woven fabric made of a single fiber, which is a composite fiber, is prepared as a preferred fiber, and a water punch is applied to the non-woven fabric to divide the fiber. Since the work to complete is completed at once, the fabric can be obtained at a low price. The condition of water pressure The method of using a thin fiber as it is as a non-woven fabric is prone to problems in processing, particularly when passing through a card machine.

  It is preferable that such a water splitting composite fiber can be split and entangled at as low a water pressure as possible, but usually 5 MPa or more is necessary, and splitting and entanglement at a low water pressure requires a fiber that can be split at a low water pressure. When forming a spread sheet with a card machine or during the stretching process when making raw cotton, it becomes difficult to make a product. On the other hand, if the maximum is 25 MPa or less, an appropriate void amount can be obtained.

  In order to further improve water absorption into the water absorption layer, a water absorbing agent is preferably adhered to the surface of the fiber. A water-absorbing agent such as silicone, polyester, or polyamide can be applied to the fiber surface with an adhesive. Any material can be used as long as water absorption can be obtained.

  The performance of the water absorption layer is preferably 4 seconds or less in the dropping method of the water absorption rate shown in JIS L1907 (1994).

  Furthermore, it is preferable that the fiber which comprises a water absorption layer has antimicrobial property, and it is preferable that the antimicrobial agent is provided for it. For example, in order to prevent the growth of Escherichia coli or Staphylococcus aureus, an organic or inorganic antibacterial agent is preferably added. Any one having antibacterial properties can be used, but organic substances such as quaternary ammonium salt compounds and chlorhexidine can be used, and inorganic substances such as silver zeolite and copper sulfide can be used. Moreover, imparting antibacterial properties is preferable because it prevents odors generated by bacteria. As a means for applying such an antibacterial agent, a method of kneading into a synthetic fiber and adhering to the surface together with an adhesive during post-processing can be used. The antibacterial property is measured by a unified test method specified by the Textile Products New Function Evaluation Council.

  The waterproof layer is made of a synthetic resin film. Such a film can be any material such as fluorine, polyamide, urethane, polyester, polyolefin, etc., but it is preferable to use a urethane film from the viewpoint of durability, cost, prevention of uncomfortable feeling during use, and the like. The water pressure resistance is required to be 50 KPa or more as measured by JIS L1092 waterproof test method B method (high water pressure method).

In the water-absorbing material of the present invention, it is necessary that the water-absorbing layer and the waterproof layer are directly bonded almost entirely.
For example, it is not preferable that only the periphery is connected to a limited portion by sewing. For example, in applications in which washing is repeated such as for bedding sheets, diapers, and incontinence pants, the water absorption layer and the waterproof layer have subtle differences in washing shrinkage, which may cause a phenomenon such as large sag and sagging, which is not preferable as a product. Further, it takes time for sewing in the product processing step, which is not preferable in terms of price. Furthermore, if both are united together, the handleability is good, the handling time is thin, and there is no bulkiness in practical use. As described above, it is not preferable to combine only a limited portion of the portion where the water-absorbing layer and the waterproof layer are opposed to each other, and it is necessary that the present invention is bonded over almost the entire surface, but not all the portions are required. There is no need to join up.

  Conventionally, a fabric in which a synthetic resin film is attached to a knitted fabric or the like has been treated as a waterproof cloth. The product is partially bonded to the water-absorbing material, but the present invention directly attaches the synthetic resin film directly to the water-absorbing layer, so there is no need for knitting, etc., and it can be finished at a low cost and in a lightweight and compact manner. .

  If the waterproof layer has a problem in strength only with the synthetic resin film, a reinforcing material, for example, a fabric such as a knitted fabric may be attached to the opposite surface of the water absorbing layer side.

  As a means for joining the water absorbing layer and the waterproof layer, there is a means for adhering the waterproof layer film to the fabric of the water absorbing layer with an adhesive. Any adhesive may be used, but synthetic resin adhesives such as urethane, polyamide, polyester, and acrylic are preferable.

  Furthermore, in the water-absorbing material of the present invention, it is preferable that a fabric having characteristics different from those of the water-absorbing layer is located on the surface of the water-absorbing layer. Fabrics having characteristics different from those of the water-absorbing layer are usually used on the skin / human body side when used as sanitary sheets, and the wet feeling can be reduced by such a configuration. Any fabric such as a woven fabric, a knitted fabric, and a non-woven fabric can be used as the fabric having characteristics different from those of the water absorbing layer, but a knitted fabric is preferable from the viewpoint of flexibility.

  The material used for the fabric having different characteristics from the water-absorbing layer used in the present invention is not particularly limited. Natural fibers such as cotton, hemp, wool and silk, chemical fibers such as rayon and acetate, polyester and polyamide Synthetic fibers such as acrylic, polypropylene, polyethylene, etc. may be used, but preferably fibers such as natural fibers and rayon absorb water in the fibers themselves, so it takes time to dry after washing, and a feeling of wetness tends to remain. Therefore, synthetic fibers such as polyester and polypropylene are better.

The fabric having characteristics different from those of the water-absorbing layer used in the present invention should have a large air permeability, and is preferably 100 cc / cm ² or more. If it is less than 100 cc / cm ² , moisture permeation may be hindered or wetted to cause a feeling of wetting. It is up to about 500cc / cm ² so many people is good, but too large, the water-absorbing layer becomes wet discomfort in contact with the human body.

  The measurement method of the air flow rate is based on the air permeability measurement method A of JIS L1096.

Moreover, in order to further reduce the wet discomfort of the fabric having different characteristics from the water-absorbing layer of the present invention, it is preferable that the surface layer in contact with the skin and the other layers have different fibers or structures. For example, the surface layer is composed of thick fibers to facilitate moisture permeation and has a rough structure, and the other layers are composed of fine fibers to form a dense structure. This is because the other layer absorbs and diffuses it, so that the wet feeling is improved and the moisture transfer is performed quickly.
Various methods can be used to bond the surface fabric and the water-absorbing layer. For example, a method such as partial sewing using a thread or full adhesion using an adhesive can be used. The surface layer can be used in any form of woven fabric, knitted fabric, non-woven fabric and the like. In particular, knitting can be preferably used in terms of softness.

   Hereinafter, the present invention will be described in more detail with reference to examples.

  In addition, the evaluation method used for this invention is demonstrated.

(1) Void amount of water-absorbing layer: The void amount per 100 m ^{2 of the} water-absorbing layer is represented by the following formula.

Void volume per 100 m ^{2 of} fabric = (volume per 100 m ² of fabric)-(volume of fibers constituting 100 m ² of fabric)
Fabric volume fabric per 100m2 thickness 5cm above overlapping the fabric water-absorbing layer, size and sample over vertically and horizontally 10 cm, thickness under a load of 10 gf / cm ² to remove excess voids such as wrinkles at the start Now, measure the size of the vertical and horizontal, and calculate by repeating the number of stacked sheets.

  (2) Water absorption: According to JIS-L-1912 (1977) “Medical Nonwoven Testing Method”.

  (3) Water pressure resistance: According to JIS-L-1092 (1998) “Waterproof test of textile products (high water pressure method)”.

(4) Compressibility of the fabric-like water absorbent: The measurement of the compressibility of the fabric-like water-absorbent is 10 gf / cm in order to remove excess voids such as wrinkles at the beginning by stacking the fabric-like water-absorbent on a sample of 5 cm or more in thickness. after pre-compressed under ² load, measuring the thickness under a load of 0.5 gf / cm ² and T1, it is calculated as a subsequent 10 gf / cm @ 2 T2 to measure the thickness under a load of at following formula .
Compression rate (%) = (T1-T2) × 100 / T1.

  (5) Water absorption rate of the fabric: According to the dropping method of JIS-L-1907 (1997) “Method for testing water absorption of textile products”.

  (6) Thickness of the fabric-like water-absorbing material: According to B method of JIS-L-1913 (1998) “General Short Fiber Nonwoven Fabric Test Method”.

  (7) Aeration rate: According to method A of JIS-L-1096 (1999) “General Textile Testing Method”.

Example 1
As the water absorption layer, it is a composite fiber of polybutylene terephthalate and nylon 6, which has a cross-sectional shape with a mandarin orange cross section, and the actual equivalent part is nylon, and polybutylene terephthalate is placed in the isolated part between the fruit and fruit. A sheet having a total thickness of 1.9 dtex and 38 mm, which is divided into 7 pieces, each of which is divided into 6 pieces and one part separating the fruit, was spread on a card machine to prepare a sheet. After laminating a plurality of such sheets, a water jet punching machine was used as a pre-punch at a water pressure of 2 Mpa once for each of the front and back surfaces, and then a water pressure of 10 Mpa for each of the front and back surfaces was passed twice for a total of 6 times to create a nonwoven fabric that would become a water absorbing layer. The water absorption layer had a basis weight of 180 g / m ² .

  The water-absorbing layer 1 and a 13 μm-thick polyurethane film were laminated and integrated with a laminate M / C using a solvent-type urethane adhesive to produce a water-absorbing material 1.

Example 2
Using two types of polyester yarn, 55 dtx12 filament and 55 dtx46 filament, a fabric having different characteristics from the water-absorbing layer was prepared with a tricot knitting machine so as to have a two-layer structure.

  Next, the water-absorbing material prepared by the same material and method as in Example 1 and the 55 dtx46 filament of this fabric are arranged so as to be on the water-absorbing layer side, and are bonded and integrated with a solvent-type urethane adhesive over almost the entire surface. Material 2 was created.

Comparative Example 1
As a water absorbing layer, a polyethylene terephthalate fiber having a fineness of 3.3 dtex, 51 mm and a solid round cross section was opened by a card machine to prepare a sheet. After laminating a plurality of such sheets, a water jet punching machine was used as a pre-punch to perform the front and back treatment once each at a water pressure of 2 Mpa, and then the water pressure was 10 Mpa. The basis weight of this water absorption layer was 80 g / m ² .
The water-absorbing layer and the polyurethane film were laminated, and the water-absorbing material as a comparative example was created by sewing the periphery partly using a sewing thread.

  The properties and performance of each layer used in Examples and Comparative Examples are shown in Table 1.

As a result of creating a waterproof sheet as an example, the water-absorbing materials 1 and 2 of the present invention were cut and sewn very easily in processing as compared with the comparative example.
The product shape was stable, and there was no appreciable feeling, making it possible to make a slim product.
Furthermore, as a result of practical use, there was no leakage at all in the two types of Example products, and in particular, Example 2 did not feel any wet feeling, whereas the comparative example had both leakage and wet feeling severe.
Furthermore, when the industrial washing was repeated 10 times, the shape change was small for both of the two types of the present invention products, whereas the comparative example was in a state where the shape change was severely unusable.

  The absorbent according to the present invention has a high water absorption amount, is excellent in no wet feeling, and is excellent in waterproofness, industrial washing resistance, and processability, so bedding such as bedding and bedding covers, diapers, incontinence pants, etc. It can be suitably used for excrement care wearing materials and foot wipe mats.

Claims (13)

The water-absorbing material is composed of at least a water-absorbing layer and a waterproof layer, and both layers are bonded over almost the entire surface. The water-absorbing layer is composed of fibers, the amount of voids per 100 cm ² is 10 cc or more, and the thickness is 1 mm to 20 mm. The water-absorbing material is characterized in that the fibers constituting the water-absorbing layer are mainly synthetic fibers and have a thickness of 0.01 to 2 dtex, and the waterproof layer is a synthetic resin film.   The water-absorbing material according to claim 1, wherein a water-absorbing agent is applied to the fibers constituting the water-absorbing layer.   The water-absorbing material according to claim 1, wherein the fibers constituting the water-absorbing layer have antibacterial properties.   The water-absorbing material according to any one of claims 1 to 3, wherein the water-absorbing layer includes a plurality of layers of the same kind.   The water absorbing material according to any one of claims 1 to 4, wherein the waterproof layer has a water pressure resistance of 50 kpa or more.   The water-absorbing material according to any one of claims 1 to 5, wherein the synthetic resin film constituting the waterproof layer is a polyurethane film. On the surface of the water-absorbing layer, a fabric having characteristics different from those of the water-absorbing layer is further located. The fabric is provided with a water-absorbing agent and has an air permeability of 100 cc / cm ² / sec or more. The water-absorbing material according to any one of claims 1 to 6, wherein the fabric is fixed to the whole surface or a part thereof.   The water absorbing material according to any one of claims 1 to 7, wherein the water absorbing material is for bedding or a cover for bedding.   The water absorbing material according to any one of claims 1 to 7, wherein the water absorbing material is for excretion care wearing materials.   The water absorbent material according to any one of claims 1 to 7, which is used for a foot wiping mat. Bedding using the water absorbing material according to any one of claims 1 to 7. An excretion care wearing material using the water absorbing material according to claim 1. A foot-wiping mat using the water-absorbing material according to claim 1.