JP4804118B2 - Laminated sheet and method for producing the same - Google Patents

Description

  The present invention relates to a laminated sheet having excellent water absorption, and particularly relates to a laminated sheet suitable for constituting a wiper having a high wiping property for dirt and little liquid remaining on an object after wiping.

  Conventionally, non-woven fabrics using split-type composite fibers have been used as wipers with high wiping properties. For example, in JP-A-10-280262 (Patent Document 1), two-component split composite short fibers (30 to 70% by weight) having different melting points and water-absorbing short fibers (70 to 30% by weight) are included. High-pressure liquid flow treatment is applied to the blended nonwoven web to develop ultra-fine split short fibers composed of a low-melting polymer and a high-melting polymer and three-dimensional entanglement, and then the low-melting polymer melts and softens. Nonwoven fabrics that can be used for wipers or the like in which constituent fibers are heat-bonded by heat treatment at a temperature have been proposed. In JP-A-11-217757 (Patent Document 2), two-component split-type composite short fibers (30 to 70% by weight) different from any of ester polymers, amide polymers, and ethylene polymers are disclosed. A non-woven web mixed with water-absorbing short fibers (70 to 30% by weight) is subjected to a high-pressure liquid flow treatment, and is split at a splitting rate of 85% or more to develop split-fiber short fibers and three-dimensionally entangled. Nonwoven fabrics that can be used for wipers and the like have been proposed. Furthermore, Japanese Patent Application Laid-Open No. 11-247059 (Patent Document 3) discloses a mixture of two-component split-type composite short fibers (90 to 60% by weight) and heat-bonding short fibers (10 to 40% by weight). A high pressure liquid flow treatment is applied to the woven web to develop ultrafine split short fibers composed of a low melting point polymer and a high melting point polymer and three-dimensional entanglement, and then at a temperature at which the heat-adhesive short fibers melt and soften. Nonwoven fabrics that can be used for wipers and the like that have been treated to thermally bond constituent fibers to each other have been proposed. Furthermore, Japanese Patent Laid-Open No. 2001-190469 (Patent Document 4) discloses a split type composite fiber on at least one surface of a hydrophilic fiber layer containing 50% by weight or more of hydrophilic fibers having an average fiber length of less than 20 mm. May be used as a nonwoven fabric for wiping, in which an ultrafine fiber layer having an average fiber length of 30 to 100 mm is disposed and integrated by three-dimensional entanglement. Proposed.

  A non-woven fabric for wiping, but a non-woven fabric having a structure similar to the non-woven fabric for wiping described in Patent Document 4, is proposed in Japanese Patent Laid-Open No. 54-82481 (Patent Document 5). This document is a non-opening that consists of staple-like short fibers as a non-woven fabric with excellent drape and physical properties, where the fibers are joined by partial thermocompression bonding, and there are many unbound free ends. Nonwoven fabric in which the short fiber web (B) and the base material (A) are integrated by superimposing the short fiber web (B) on the base fabric (A) and spraying a water flow onto the web And further proposes to use a nonwoven fabric composed only of regenerated cellulose fibers as the substrate (A).

Japanese Patent Laid-Open No. 10-280262 JP 11-217757 A JP-A-11-247059 JP 2001-190469 A JP 54-82481 A

  However, the nonwoven fabric has the following problems. For example, the nonwoven fabric described in Patent Document 1 contains 70 to 30% by weight of water-absorbing short fibers, and is excellent in absorbability such as moisture. However, there was a lot of liquid remaining after wiping, and not only remained as a liquid when the target surface was dried, but also the wiping property was insufficient, so that only dirt remained as liquid was obtained. The nonwoven fabric described in Patent Document 2 attempts to improve the wiper performance by setting the splitting rate of the two-component split-type composite short fibers to 85% or more. However, the liquid residue could not be eliminated as in Patent Document 1. The nonwoven fabric described in Patent Document 3 contains 10 to 40% by weight of heat-adhesive short fibers having a melting point 30 ° C. or more lower than the melting point of the polymer constituting the split-type two-component composite short fibers, and the ultrafine split short fibers Attempts have been made to obtain a nonwoven fabric excellent in form stability and abrasion resistance of the nonwoven fabric by thermally bonding the heat-adhesive short fibers without melting them. However, not only water absorption is insufficient and the liquid residue is large, but the fineness of the heat-adhesive short fibers is large and the wiping property is inferior.

  The nonwoven fabric described in Patent Document 4 employs a laminated structure to reduce the exposure of hydrophilic fibers on the surface of the ultrafine fiber layer, thereby making it possible to reduce the liquid residue to some extent. However, when the nonwoven fabric described in Patent Document 4 is used as a wiper for an object for which it is desired to reduce liquid residue, such as a display and a glass surface, there is still room for improvement in terms of liquid residue. Have. Moreover, patent document 4 does not mention the nonwoven fabric structure suitable for making wiping off of fats and oils etc. high. Furthermore, since the nonwoven fabric described in Patent Document 4 has a small average fiber length of hydrophilic fibers, fibers are likely to fall off during use, and is not necessarily suitable for use in an environment where dust generation is not desired, such as in a clean room. It was not. The nonwoven fabric described in Patent Document 5 is not assumed to be used as a wiper, and the document does not teach a configuration of a nonwoven fabric suitable for wiper use.

  The present invention has been made in view of the above problems, and has a wiper that has a high level of wiping of dirt and that has little liquid residue on an object after wiping off a liquid or the like or wiping with a wetting agent. It aims at obtaining the laminated sheet suitable for comprising.

  As a result of studying the liquid remaining after wiping, the present inventor has included a hydrophilic fiber in the ultrafine fiber layer in the laminated sheet having a laminated structure composed of the hydrophilic fiber layer and the ultrafine fiber layer as described in Patent Document 4. It was considered that the remaining amount of liquid could be reduced by further reducing the amount exposed and reducing the amount exposed on the surface of the ultrafine fiber layer. However, when the hydrophilic fiber layer is composed of a fiber web, the hydrophilic fiber moves into the ultrafine fiber layer when integrated with the ultrafine fiber layer by hydroentanglement treatment. It is difficult to reduce the amount contained in. Therefore, as a result of further examining the configuration of the hydrophilic fiber layer, the hydrophilic fiber layer is composed of a nonwoven fabric in which hydrophilic fibers are point-bonded and / or entangled with each other, and after being integrated with the ultrafine fiber layer, When the laminated sheet is configured so that the point bond region or the fiber entanglement region before being integrated with the ultrafine fiber layer is maintained in the hydrophilic fiber layer, the amount of hydrophilic fibers mixed in the ultrafine fiber layer is reduced, The present inventors have found that the above problems can be solved, and have reached the present invention.

That is, the present invention is a laminated sheet in which an ultrafine fiber layer containing ultrafine fibers is laminated on both sides of a hydrophilic fiber layer containing hydrophilic fibers in order to solve the above-described problem,
The hydrophilic fiber layer includes a point bond region where hydrophilic fibers are bonded to each other,
The ultrafine fiber layer includes an ultrafine fiber having a fineness of 0.9 dtex or less obtained by splitting a split type composite fiber composed of a plurality of resin components,
Provided is a laminated sheet in which a hydrophilic fiber layer and an ultrafine fiber layer are integrated by hydroentanglement. This laminated sheet is characterized by having a point bond region where hydrophilic fibers are bonded to each other in a hydrophilic fiber layer integrated with an ultrafine fiber layer by hydroentanglement. After the ultrafine fiber layer and the hydrophilic fiber layer are integrated, it is ensured that the amount of hydrophilic fiber exposed on the surface of the ultrafine fiber layer is reduced by configuring the laminated sheet to have such characteristics. it can. Therefore, when this laminated sheet is used as a wiper, water absorption is ensured by the hydrophilic fiber layer, excellent wiping property is secured by the ultrafine fibers, and the liquid residue is reduced, so that the dirt on the object is removed. It becomes possible to wipe off well.

  Here, the point bond region is a region formed by, for example, thermocompression bonding using an embossing roll or the like, and in that region, the fibers adhere to each other more firmly than other regions, For example, it is a film. In the hydrophilic fiber layer, the hydrophilic fibers may be bonded in a region other than the point bond region.

Further, the present invention is a laminated sheet obtained by laminating ultrafine fiber layers containing ultrafine fibers on both sides of a hydrophilic fiber layer containing hydrophilic fibers in order to solve the above-described problems,
Before the hydrophilic fiber layer is integrated with the ultrafine fiber layer, it is a layer including a fiber entangled region in which hydrophilic fibers are entangled with each other,
The ultrafine fiber layer includes an ultrafine fiber having a fineness of 0.9 dtex or less obtained by splitting a split type composite fiber composed of a plurality of resin components,
Provided is a laminated sheet in which a hydrophilic fiber layer and an ultrafine fiber layer are integrated by hydroentanglement. When the hydrophilic fiber layer before being integrated with the ultrafine fiber layer has a fiber entanglement region in which hydrophilic fibers are entangled with each other, when the fiber is entangled with the ultrafine fiber layer later by hydroentanglement, Movement to the fiber layer can be reduced. As a result, a laminated sheet with a small amount of hydrophilic fibers exposed on the surface of the ultrafine fiber layer can be obtained. Here, what is specified in the form before the hydrophilic fiber layer is integrated with the ultrafine fiber layer is that it is difficult to distinguish the fiber entanglement region before and after the integration with the ultrafine fiber layer in the laminated sheet. by. The laminated sheet identified in this way also has the above-mentioned hydrophilic fiber layer as a point bond in that the hydrophilic fibers are relatively fixed to each other within the hydrophilic fiber layer after integration with the ultrafine fiber layer. This is common with laminated sheets having regions and is based on the same technical idea.

  The fiber entanglement region is, for example, a region formed by hydroentanglement treatment, and in that region, fibers are entangled more strongly than other regions, for example, a region having a higher fiber density is formed. ing. In the hydrophilic fiber layer, the fibers may be entangled in a region other than the fiber entanglement region. In the hydrophilic fiber layer, the region other than the fiber entangled region may be, for example, an opening before being integrated with the ultrafine fiber layer.

Further, the present invention is a laminated sheet obtained by laminating ultrafine fiber layers containing ultrafine fibers on both sides of a hydrophilic fiber layer containing hydrophilic long fibers in order to solve the above-described problem,
The ultrafine fiber layer includes an ultrafine fiber having a fineness of 0.9 dtex or less obtained by splitting a split type composite fiber composed of a plurality of resin components,
Provided is a laminated sheet in which a hydrophilic fiber layer and an ultrafine fiber layer are integrated by hydroentanglement. This laminated sheet is characterized in that the hydrophilic fiber layer includes long fibers, and the number of fiber ends of the hydrophilic long fibers in the hydrophilic fiber layer is relatively small. This feature ensures that the amount of hydrophilic long fibers exposed on the surface of the ultrafine fiber layer is reduced.

  It is preferable that the hydrophilic long fibers contained in the hydrophilic fiber layer are at least partially self-adhering. Thereby, the amount of hydrophilic long fibers exposed on the surface of the ultrafine fiber layer can be further reduced.

  In the laminated sheet of the present invention, since the hydrophilic fiber layer and the ultrafine fiber layer are integrated by the hydroentanglement process, the interface of each layer is generally unclear because the fibers are entangled with each other. However, even in such a case, for example, when a dyeing test is performed using a dye that dyes only hydrophilic fibers and a cross-section of the laminated sheet is observed, it is confirmed that a deeply dyed layer exists near the center. Is done. It should be noted that laminated sheets that can be confirmed as such are included in the laminated sheet of the present invention.

  In the laminated sheet of the present invention, the hydrophilic fiber layer contains regenerated cellulose fibers, the regenerated cellulose fibers are self-adhering to form a point void region, and / or the regenerated cellulose before being integrated with the ultrafine fiber layer. It is preferable that the fibers are entangled to form a fiber entangled region. More preferably, the hydrophilic fiber layer consists only of regenerated cellulose fibers. Such a hydrophilic fiber layer imparts good water absorption to the nonwoven fabric. Moreover, since the hydrophilic fiber layer including the point bond region by the self-adhesion between the regenerated cellulose fibers or the fiber entanglement region by the entanglement between the regenerated cellulose fibers can be formed without using the adhesive, contamination due to the use of the adhesive, etc. (For example, elution) is less likely to occur. Therefore, a laminated sheet including such a hydrophilic fiber layer is suitable for use as a wiper in a clean room, for example. Further, such a hydrophilic fiber layer is advantageous in that the fibers are hardly scattered even when subjected to hydroentanglement treatment.

  Alternatively, the hydrophilic fiber layer preferably includes a regenerated cellulose long fiber, and the regenerated cellulose long fiber is partially bonded to each other (without forming a point-bonded region). Even when such a hydrophilic fiber layer is used, the same effect as that of the regenerated cellulose fiber-containing hydrophilic fiber layer having the point bond region or the fiber entanglement region is brought about.

  In the laminated sheet of the present invention, the ultrafine fiber layer is a modified vinyl alcohol having a fineness of 0.9 dtex or less obtained by splitting a split type composite fiber comprising a component containing a modified vinyl alcohol resin and at least one other resin component. It is preferable to include an ultrafine fiber containing a resin. The ultrafine fiber containing the modified vinyl alcohol resin makes it possible to satisfactorily wipe off oil stains and the like.

The present invention also provides a method for producing the laminated sheet,
50 mass% of split type composite fibers on both sides of a hydrophilic non-woven fabric containing a point bond region where hydrophilic fibers are bonded and / or a fiber-entangled region where hydrophilic fibers are entangled. % To obtain a laminated body, and subject the laminated body to hydroentanglement treatment to split a split composite fiber to obtain ultrafine fibers with a fineness of 0.9 dtex or less and a hydrophilic nonwoven fabric And a fibrous web are provided. This method is characterized in that a hydrophilic non-woven fabric having a point bond region and / or a fiber entanglement region is used, and this is integrated with a fiber web containing split composite fibers by a hydroentanglement process. This feature makes it possible to obtain the laminated sheet of the present invention in which the hydrophilic fiber layer and the ultrafine fiber layer are integrated and the ratio of the hydrophilic fibers exposed on the surface of the ultrafine fiber layer is small.

  In the production method of the present invention, the hydrophilic nonwoven fabric preferably includes regenerated cellulose fibers, and the regenerated cellulose fibers are self-adhering to form the point bond region, and is composed only of regenerated cellulose fibers. It is more preferable that By using such a hydrophilic non-woven fabric, the fiber web and the hydrophilic non-woven fabric can be easily integrated by hydroentanglement treatment, and the amount of hydrophilic fibers that move into the ultrafine fiber layer during hydroentanglement treatment can be reduced. It can be made smaller.

The present invention further provides another method for producing the laminated sheet,
A fibrous web comprising 20 mass% or more of hydrophilic long fibers and comprising 50 mass% or more of split-type composite fibers on both sides of the hydrophilic longfiber nonwoven fabric in which the hydrophilic long fibers are at least partially self-adhering to each other. To obtain a laminated body, and to subject the laminated body to hydroentanglement treatment to split split-type composite fibers to obtain ultrafine fibers having a fineness of 0.9 dtex or less and hydrophilic long fiber nonwoven fabric and fiber web And a method comprising integrating. This method is characterized in that a hydrophilic long fiber nonwoven fabric in which long fibers are partially self-adhered is used, and this is integrated with a fiber web containing split composite fibers by a hydroentanglement process. This feature makes it possible to obtain the laminated sheet of the present invention in which the hydrophilic fiber layer and the ultrafine fiber layer are integrated and the ratio of the hydrophilic fibers exposed on the surface of the ultrafine fiber layer is small.

  The present invention also provides a wiper comprising the laminated sheet of the present invention. The wiper of the present invention is particularly suitable for wiping a wet target surface or wiping a symmetrical surface as a wet sheet impregnated with liquid, so that there is no or little liquid remaining on the target surface after wiping. It is possible to carry out.

  The laminated sheet of the present invention has a configuration in which a hydrophilic fiber layer and ultrafine fiber layers arranged on both sides of the hydrophilic fiber layer are included, and hydrophilic fibers are fixed to each other to some extent in the hydrophilic fiber layer. . By having such a configuration, when this laminated sheet is used for an application (especially a wiper) for wiping liquid from the target surface, the liquid can be absorbed well, and the amount of liquid remaining on the target surface after wiping the liquid is reduced. Can be reduced. Alternatively, when this laminated sheet is used for the purpose of wiping dirt by impregnating the laminated sheet with a liquid (for example, a cleaning agent), the liquid is satisfactorily retained in the hydrophilic fiber layer, and the dense ultrafine fiber layer becomes the exposed surface. Therefore, the liquid is not easily leached and the leached liquid is wiped off immediately, so that the liquid residue after wiping can be reduced. Furthermore, since the laminated sheet of the present invention has an exposed surface of the ultrafine fiber layer, when it is used as an application (especially a wiper) for wiping off dirt or adhering matter from the target surface, dirt and the like are good due to the ultrafine fiber. Can be wiped off to give a clean target surface.

  In the laminated sheet of the present invention, when the ultrafine fiber layer is a layer containing ultrafine fibers containing a modified vinyl alcohol resin, the ultrafine fibers containing the modified vinyl alcohol resin particularly absorb oil and fat. Can be wiped off satisfactorily when used as an application (especially a wiper) for wiping oil from the target surface.

  The wiper including the laminated sheet of the present invention has the above-described characteristics, and there is little liquid residue when the liquid is wiped from the target surface, and the ultrafine fiber layer contains ultrafine fibers containing a modified vinyl alcohol resin. In this case, the oil and fat stains can be wiped off satisfactorily. Therefore, the wiper of the present invention is a wiper for wiping off a surface to which oily and dirt such as OA equipment such as a display, glasses, an automobile, a machine, and a copying machine is adhered, or a dry wipe after cleaning with a cleaning liquid. Works well as a windshield wiper. Further, since the wiper including the laminated sheet of the present invention can be configured without using an adhesive that may cause contamination, it can be used in a clean room.

  The laminated sheet of the present invention includes 1) a hydrophilic fiber layer including a point bond region where hydrophilic fibers are bonded to each other, and 2) a fiber in which hydrophilic fibers are entangled before being integrated with the ultrafine fiber layer. A hydrophilic fiber layer containing an entangled region, or 3) a split type comprising a hydrophilic long fiber layer containing hydrophilic long fibers, and preferably hydrophilic long fibers partially self-adhering to each other, and a plurality of resin components It consists of an ultrafine fiber layer containing ultrafine fibers with a fineness of 0.9 dtex or less obtained by splitting the composite fiber, and the ultrafine fiber layers are arranged on both surfaces of the hydrophilic fiber layer and integrated with the hydrophilic fiber layer It is a sheet. Here, the term “surface” refers to the main surface (surface parallel to the thickness) of the sheet or layer.

  In the laminated sheet, the hydrophilic fiber layer includes a layer including a point bond region in which hydrophilic fibers are bonded to each other, and / or a fiber entangled region in which hydrophilic fibers are entangled before being integrated with the ultrafine fiber layer. Or a hydrophilic long fiber layer having hydrophilic long fibers. These hydrophilic fiber layers have a point bond region and / or a fiber entangled region before they are integrated with the ultrafine fiber layer by hydroentanglement, or include hydrophilic long fibers, preferably the hydrophilic long fibers are at least It is generally required to be a non-woven fabric that is partially bonded and can be handled as an independent sheet. Hereinafter, the hydrophilic fiber layer before constituting the laminated sheet, that is, the hydrophilic nonwoven fabric will be described.

  The hydrophilic nonwoven fabric preferably contains regenerated cellulose fibers, and the regenerated cellulose fibers are self-adhering to each other. Here, “regenerated cellulose fiber” refers to viscose rayon, copper ammonia rayon (cupra), solvent-spun cellulose fiber, and the like. Further, “regenerated cellulose fibers self-adhere” means that a part of the regenerated cellulose fibers are melted or softened and joined to each other without using an adhesive. Such bonding is achieved by modifying a portion of the regenerated cellulose fiber or by utilizing the viscosity immediately after spinning of the regenerated cellulose fiber.

  Specifically, as a hydrophilic non-woven fabric, a fiber web containing rayon staple fibers having a portion composed of a methylolated derivative of cellulose xanthate is prepared, and subjected to thermocompression treatment using an emboss roll or the like, so that cellulose xanthate A nonwoven fabric in which a point bond region in which fibers are bonded to each other is formed by melting a methylol derivative. This nonwoven fabric preferably consists only of such rayon staple fibers. The fiber entangled region is formed by further subjecting the nonwoven fabric in which the point bond region is formed, for example, to hydroentanglement treatment. A nonwoven fabric made of rayon staple fibers having a point bond region and a nonwoven fabric made of rayon staple fibers having a point bond region and a fiber entanglement region are sold, for example, by Futamura Chemical Co., Ltd. under the name “Taiko TCF”. “Taiko TCF” is described in “Nonwoven fabric information” (March 10, 2004, Nonwoven fabric information issuance).

In the hydrophilic nonwoven fabric having a point bond region, the point bond regions are preferably formed at a rate of 10 to 60 pieces / cm ² and occupy 5% to 60% of the nonwoven fabric surface. If the number and ratio of the point bond regions are small, the ultrafine fiber layer tends to include more hydrophilic fibers, and the effects of the present invention cannot be obtained. If the number and ratio of the point bond regions are large, the hydrophilic nonwoven fabric There is a tendency that the bonding force between the fiber and the ultrafine fiber layer becomes small.

  Alternatively, the hydrophilic non-woven fabric is preferably a long-fiber non-woven fabric obtained by spinning the regenerated cellulose fiber and partially bonding the fibers while the spun fiber has viscosity. This long-fiber nonwoven fabric is also preferably composed only of regenerated cellulose fibers. When this long fiber nonwoven fabric is further subjected to hydroentanglement treatment, it becomes a nonwoven fabric having a fiber entanglement region. A long-fiber nonwoven fabric made only of regenerated cellulose fibers is sold, for example, by Asahi Kasei Fibers Corporation under the name “Benlyse” and from Ozu Sangyo Co., Ltd. under the name “Bencot”. “Benlyse” and “Bencot” are non-woven fabrics consisting only of cupra. Nonwoven fabrics sold under these names include various forms, including those having a fiber entanglement region that has been subjected to hydroentanglement treatment.

  Alternatively, the long fiber nonwoven fabric may have a sheet form in which the long fibers are not bonded to each other and the fibers are entangled by a hydroentanglement process or the like. Such a long fiber nonwoven fabric can constitute a hydrophilic fiber layer having a fiber entangled region in the present invention.

  When the hydrophilic fiber layer is a layer containing hydrophilic long fibers, the hydrophilic fiber layer before being integrated with the ultrafine fiber layer has a form in which the long fibers are not bonded or entangled, that is, a long fiber web. It's okay. Since such a long fiber web is difficult to handle as an independent sheet, the laminated sheet is produced by, for example, a method in which the long fiber web is integrated with the ultrafine fiber layer immediately after the long fiber web is formed.

  The hydrophilic nonwoven fabric does not necessarily have to be self-adhered between regenerated cellulose fibers, and may be a sheet in which hydrophilic fibers are adhered to each other with an adhesive. As the hydrophilic fiber, in addition to the above-mentioned regenerated cellulose fiber, one or a plurality of fibers selected from natural fibers such as cotton, pulp, silk and wool, and those obtained by subjecting synthetic fibers to a hydrophilic treatment can be used. As the adhesive, it is possible to use adhesives and heat-adhesive fibers that are generally used in the production of nonwoven fabrics.

  Specifically, the hydrophilic non-woven fabric may be a non-woven fabric that is point-bonded using an embossing roll or the like by applying an adhesive to a fiber web such as a wet papermaking web and a card web containing the fibers, or hydrophilic. Fabricate a fiber web containing fibers and heat-adhesive fibers, and then apply needle punching or hydroentanglement as needed, then heat-treat and bond the fibers together with heat-adhesive fibers to form point bond areas It may be a non-woven fabric. As the heat-adhesive fiber, for example, a composite fiber that is composed of a combination of a low-melting resin component and a high-melting resin component, and the low-melting resin component is exposed on at least a part of the fiber surface can be used. Specifically, the low melting point resin component / high melting point resin component is polyethylene / polypropylene, polyethylene / polyethylene terephthalate, ethylene-propylene copolymer / polypropylene, ethylene-propylene copolymer / polyethylene terephthalate, etc. In the above, those having a low melting point resin component / high melting point resin component having a sheath / core structure or having a parallel structure are used.

  The hydrophilic nonwoven fabric preferably includes at least 20 mass% or more of hydrophilic fibers in any form. In the hydrophilic nonwoven fabric, when the ratio of the hydrophilic fiber is less than 20 mass%, good water absorption cannot be obtained in the resulting laminated sheet. The hydrophilic nonwoven fabric preferably consists of hydrophilic fibers only. As described above, the sheet made of only hydrophilic fibers is preferably realized as a sheet having a structure in which a part of the regenerated cellulose fibers are self-adhered.

The hydrophilic nonwoven fabric is preferably that the basis weight is in the range of 10 g / ^{m 2} or more 180 g / ^{m 2} or less, and more preferably in a 15 g / ^{m 2} or more 60 g / ^{m 2} within the following ranges. When the basis weight of the hydrophilic nonwoven fabric is less than 10 g / m ² , good water absorption cannot be imparted to the laminated sheet, and the texture of the laminated sheet becomes poor. When the basis weight of the hydrophilic nonwoven fabric exceeds 180 g / m ² , the water absorption of the laminated sheet formed with the hydrophilic fiber layer is improved. However, when the hydrophilic fiber layer holds a large amount of liquid, the liquid is pressed by pressing. Since it may flow out of the laminated sheet, when the laminated sheet is used as a wiper, water flowing out from the hydrophilic fiber layer may cause a liquid residue. Here, the preferred basis weight of the hydrophilic non-woven fabric is described, but the basis weight of the hydrophilic non-woven fabric is finally obtained even if the hydrophilic fiber is slightly reduced by moving to the ultrafine fiber layer during hydroentanglement treatment. It can be considered that it is substantially the same as the basis weight of the hydrophilic fiber layer in the laminated sheet. Therefore, it should be noted that the preferred basis weight range of the hydrophilic nonwoven fabric is the preferred basis weight range of the hydrophilic fiber layer in the laminated sheet.

  Next, the ultrafine fiber layer will be described. In the laminated sheet of the present invention, the ultrafine fiber layer includes ultrafine fibers having a fineness of 0.9 dtex or less obtained by splitting the split type composite fibers. The split-type conjugate fiber is composed of a plurality of resin components, and at least one component of the constituent components is divided into two or more in the fiber cross section, and at least a part of the constituent components are exposed on the fiber surface, and the exposed portion is It has a fiber cross-sectional structure formed continuously in the fiber length direction. Examples of the fiber cross-sectional structure of the split type composite fiber composed of two resin components are shown in FIGS. In FIG. 1, only a split type composite fiber composed of two components is illustrated, but the split type composite fiber may be composed of three or more components. Alternatively, the split type composite fiber may have a hollow. In that case, the ratio of the hollow to the fiber cross section (that is, the hollow ratio) is preferably about 1 to 50%.

  The ultrafine fiber formed by splitting the split type composite fiber has a fineness of 0.9 dtex or less. The lower limit of the fineness of the ultrafine fiber is preferably 0.05 dtex, and the upper limit thereof is preferably 0.6 dtex. When the fineness of the ultrafine fiber exceeds 0.9 dtex, there is a possibility that the liquid residue on the object increases.

  In the present invention, the split-type composite fiber is preferably a split-type composite fiber composed of a component containing a modified vinyl alcohol resin and at least one other resin component (this split-type composite fiber is referred to as “split-type composite fiber”). Also referred to as “fiber (A).” The split-type composite fiber (A) is split to form an ultrafine fiber containing a modified vinyl alcohol resin. The ultrafine fiber containing a modified vinyl alcohol resin is compared with a liquid such as water. Therefore, the liquid can be well absorbed into the hydrophilic fiber layer inside the laminated sheet by utilizing the capillary phenomenon of the modified vinyl alcohol-containing ultrafine fibers entangled on the surface of the nonwoven fabric. Since the alcohol-containing ultrafine fiber has excellent adsorptivity to fat and oil components, the laminate of the present invention exists on the sheet surface and inside the ultrafine fiber layer. Over DOO has excellent wiping properties of greasy soils, and can effectively hold the fats and oils.

  The modified vinyl alcohol resin is a copolymer resin of vinyl alcohol and another monomer. The vinyl alcohol content in the modified vinyl alcohol resin is preferably in the range of 50 mol% to 70 mol%. A more preferable vinyl alcohol content is 55 mol% or more. A more preferable vinyl alcohol content is 65 mol% or less. When the vinyl alcohol content is less than 50 mol%, the wettability is lowered, and the liquid residue and liquid wettability on the target surface may be lowered. If the vinyl alcohol content exceeds 70 mol%, the wettability tends to increase, and the liquid residue may increase. Examples of other monomers include α-olefins such as ethylene, propylene, 1-butene, isoprene and 1-hexene. The modified vinyl alcohol resin is particularly preferably an ethylene-vinyl alcohol copolymer (hereinafter referred to as EVOH) having an ethylene content in the range of 30 mol% to 50 mol%. According to the EVOH, the liquid does not get wet more than necessary with respect to a liquid such as water, and exhibits an appropriate wettability. Moreover, according to said EVOH, it is excellent in the adsorptivity of an oil-and-fat component, and excellent in the retention of oil-and-fat dirt. A more preferable ethylene content is 35 mol% or more. The ethylene content is more preferably 45 mol% or less.

  The modified vinyl alcohol resin forms one component of the split composite fiber (A) alone or in the form of a mixture with other resins. When using the mixture of modified vinyl alcohol resin and other resin, it is preferable that the ratio of modified vinyl alcohol resin is 50 mass% or more. When the ratio of the modified vinyl alcohol resin is less than 50 mass%, the oil and fat component adsorptivity of the obtained ultrafine fiber may be insufficient. Examples of other resins to be mixed with the modified vinyl alcohol resin include polyethylene, ethylene-acrylic acid copolymer, ethylene-methyl acrylate, polyvinyl alcohol, and ionomer. The modified vinyl alcohol resin is preferably alone (that is, without being mixed with another resin) and constitutes a split-type composite fiber with another resin component.

  At least one of the other resin components constituting the split-type conjugate fiber (A) together with the resin component containing the modified vinyl alcohol resin is, for example, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, nylon 6 and nylon 66, etc. It is preferable to contain one or a plurality of resins selected from polyolefin resins such as polyamide resin and polypropylene, and it is more preferable to contain a polyolefin resin. Therefore, when the split type composite fiber (A) is composed of the first component and the second component as shown in FIG. 1, the first component contains the modified vinyl alcohol resin, and the second component contains the polyolefin resin. It is preferable to do. The combination of the resin component containing the modified vinyl alcohol resin and the resin component containing the polyolefin resin is easy to split by hydroentanglement treatment, and an ultrafine fiber containing the modified vinyl alcohol resin can be easily obtained. The split type composite fiber comprising a resin component containing a modified vinyl alcohol resin and a resin component containing a polyolefin resin comprises a modified vinyl alcohol-containing ultrafine fiber exhibiting moderate liquid wetting and a polyolefin-containing ultrafine fiber exhibiting hydrophobic properties. Therefore, the wettability of the surface of the ultrafine fiber layer with respect to the liquid (for example, water) or the slipperiness on the surface to be wiped can be adjusted by changing the ratio of the two. Examples of the polyolefin resin include resins such as polyethylene, polypropylene, polybutene-1, and polymethylpentene, or copolymer resins thereof (for example, ethylene-propylene). These resins are used alone or in combination. You can do it. Among these, polypropylene resin is particularly preferably used because it is excellent in handleability.

  The polyolefin resin forms one component of the split composite fiber (A) alone or in the form of a mixture with other resins. When using the mixture of polyolefin resin and other resin, it is preferable that the ratio of polyolefin resin is 50 mass% or more. When the proportion of the polyolefin resin is less than 50 mass%, the splitting property of the split-type composite fiber (A) may be lowered, and the hydrophobicity of the polyolefin-containing ultrafine fiber may be insufficient. Examples of other resins to be mixed with the polyolefin resin include ionomers. The polyolefin resin is preferably alone (that is, without being mixed with other resins) and constitutes a split-type composite fiber with a resin component containing a modified vinyl alcohol resin.

  The volume ratio (modified vinyl alcohol-containing resin / other resin) between the component containing the modified vinyl alcohol resin and the other resin component in the split composite fiber (A) is in the range of 9/1 to 1/9. It is preferable. A more preferable volume ratio is 6/4 to 4/6. When the volume ratio of the resin component containing the modified vinyl alcohol resin to the other resin components in the split composite fiber (A) is less than 1/9, the proportion of the modified vinyl alcohol-containing ultrafine fibers in the ultrafine fiber layer is small. Therefore, the liquid remaining on the object tends to increase. When the volume ratio exceeds 9/1, the proportion of the modified vinyl alcohol-containing ultrafine fibers in the ultrafine fiber layer increases, and the productivity of the fibers may decrease.

  The ultrafine fiber layer may include ultrafine fibers obtained by splitting other split composite fibers in place of or together with the split composite fibers (A). For example, the ultrafine fiber layer is a split of a split-type composite fiber (this split-type composite fiber is referred to as “split-type composite fiber (B)”) composed of a component containing a thermal adhesive resin and at least one other resin component. A heat-adhesive ultrafine fiber obtained by fiber may be included. Since the heat-adhesive ultrafine fiber has a small fineness, there are many intersections with other fibers, and the fibers can be bonded to each other while maintaining fine voids. Therefore, the laminated sheet containing the heat-adhesive ultrafine fibers is lightly wiped, and gives a wiper with less fiber dropping and less liquid residue during wiping. In addition, when the fibers in the ultrafine fiber layer are bonded to each other with only the heat-adhesive ultrafine fiber (for example, when the heat-adhesive fiber having a high fineness is not mixed with the ultrafine fiber layer), the target surface is not damaged. It is preferable because the effects of preventing the fibers from falling off, improving the wiping property, and reducing the liquid residue can be maximized.

  The thermoadhesive resin is one or more resins selected from resins conventionally used in the production of synthetic fibers, such as low density and high density polyethylene, ethylene-propylene copolymers and low melting point polyesters. It is preferable. These heat-adhesive resins may be mixed with other high-melting point resins as necessary, and may be used as one component of split-type composite fibers. In that case, the ratio of the heat-adhesive resin in the entire ultrafine fiber layer is preferably 5 mass% or more, and more preferably 10 mass% or more. If the proportion of the heat-adhesive resin in the ultrafine fiber layer is less than 5 mass%, the fibers may not be sufficiently bonded to each other by the heat-adhesive ultrafine fibers. Preferably, the thermoadhesive resin is used without being mixed with other high melting point resins. The other resin component constituting the split-type conjugate fiber together with the resin containing the heat-adhesive resin is one or a plurality of resins having a melting point higher than the melting point of the heat-adhesive resin, preferably higher than 20 ° C. For example, it is selected from polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyamide resins such as nylon 6 and nylon 66, polyolefin resins such as polypropylene, polybutene-1, and polymethylpentene. When the split-type conjugate fiber (B) is composed of the first component and the second component as shown in FIG. 1, the first component contains a heat-adhesive resin, and the second component contains one or more high components. Made of melting point resin.

  The volume ratio (thermoadhesive resin-containing resin / other resin) of the resin containing the thermoadhesive resin and the other resin in the split-type conjugate fiber (B) is in the range of 9/1 to 1/9. It is preferable. A more preferable volume ratio is 6/4 to 4/6. If the volume ratio of the resin containing the heat-adhesive resin and the other resin in the split-type composite fiber (B) is less than 1/9, the proportion of the heat-adhesive ultrafine fibers in the ultrafine fiber layer decreases, and the fibers Sometimes it is not possible to bond them well. When the volume ratio exceeds 9/1, the proportion of the heat-adhesive ultrafine fibers increases in the ultrafine fiber layer, the ultrafine fiber layer becomes hard, and the capillary structure in the ultrafine fiber layer is crushed to absorb water from the laminated sheet. May decrease.

  The split-type conjugate fiber (B) is preferably used together with the split-type conjugate fiber (A). The ultra-fine fiber layer includes an ultra-fine fiber layer obtained by splitting the split-type composite fibers (A) and (B), and the fibers are bonded to each other by the heat-adhesive ultra-fine fibers, so that the oil and fat adsorptivity is excellent. And the laminated sheet excellent in form stability can be obtained. In that case, the fiber web which contains a split type composite fiber (A) in the ratio of 40 mass% or more and 90 mass% or less and the said split type composite fiber (B) in the ratio of 10 mass% or more and 60 mass% or less is produced. It is preferable to obtain an ultrafine fiber layer by subjecting to an entanglement treatment and a heat bonding treatment.

  The ultrafine fiber layer may include ultrafine fibers obtained by splitting other split type composite fibers together with or instead of the split type composite fibers (A) and (B). Other split-type composite fibers are those in which the resin component combination is, for example, polyethylene terephthalate / polypropylene, polyethylene terephthalate / nylon 66, polyethylene terephthalate / nylon 6, or polymethylpentene / polypropylene.

  The resin component which comprises the said split-type composite fiber (A) and (B) and another split-type composite fiber may contain a hydrophilizing agent as needed. When the resin component of the split-type composite fiber contains a hydrophilizing agent, the resulting ultrafine fiber has hydrophilicity, and the hydrophilicity of the laminated sheet is improved. The hydrophilizing agent may be any compound that has a hydrophilic group such as a hydroxyl group, a carbonyl group, a carboxyl group, or a sulfone group. Examples of the hydrophilizing agent include fatty acid glyceride (monoglycerin fatty acid ester), alkoxylated alkylphenol, polyoxyalkylene fatty acid ester, and fatty acid diethanolamide. The hydrophilizing agent preferably has a hydrophilic performance for a longer period of time (that is, has hydrophilic durability) or has a slow bleed speed to the fiber surface (has hydrophilic slow-acting properties). As a hydrophilizing agent having properties, specifically, an ester compound of a polyglycerin having a polymerization degree (n) of 2 to 10 and a saturated or unsaturated fatty acid having 8 to 22 carbon atoms (hereinafter simply referred to as “polyglycerin fatty acid ester”). Also called). Polyglycerin fatty acid ester is particularly preferably used because it not only imparts hydrophilicity to the split type composite fiber but also improves its splitting property. Other commercially available hydrophilizing agents include, for example, IRGASURF (registered trademark; available from Ciba Specialty Chemicals).

  The hydrophilizing agent may be contained only in an arbitrary component or a plurality of components constituting the split-type conjugate fiber, or may be contained in all components. When a hydrophilizing agent is contained in one component, it is preferable to contain the hydrophilizing agent in an amount of 0.1 to 5 mass%, more preferably 0.3 to 3 mass%, and more preferably 0.8 to 2.5 mass. % Content is most preferable. When the content of the hydrophilizing agent is less than 0.1 mass%, the effect (improvement of hydrophilicity and / or splitting property) due to the inclusion of the hydrophilizing agent cannot be obtained, and when the content exceeds 5 mass%, This is not preferable because the yarn breakage during spinning increases and causes deterioration in quality and processability. When a hydrophilizing agent is contained in a plurality of components of the split type composite fiber, it is preferable that the content of the hydrophilizing agent contained in each component is within the above range.

  As a method of adding a hydrophilizing agent to a predetermined component, a method of supplying the hydrophilizing agent to the extruder at a predetermined ratio together with resin pellets as the component during melt spinning, or a master batch containing the hydrophilizing agent is prepared. And a method of mixing the masterbatch with resin pellets as the component. According to the method using a master batch, the hydrophilizing agent is more uniformly dispersed in the components, and therefore this method is preferably used.

  In the ultrafine fiber layer, the split-type composite fiber does not need to be completely divided into each component, for example, only a part of the component may be divided, or the ultrafine fiber is a completely independent fiber. Alternatively, one or a plurality of ultrafine fibers may be branched from one split type composite fiber. As described above, when the splitting of the ultrafine fiber in the split composite fiber is stopped halfway, the split ratio is preferably 60% or more, and more preferably 70% or more. The division ratio in the ultrafine fiber layer is determined as follows. First, it is bundled so that the machine direction (vertical direction) of the laminated sheet is a cross section so as not to create a space, and is magnified 300 times with an electron microscope, and arbitrarily taken at three locations. Next, the area obtained by subtracting the area occupied by fibers that are not split-type composite fibers, such as hydrophilic fibers, from the entire area in the photograph taken is set as the mother area for determining the split ratio. A fiber that is not a split-type composite fiber can be easily identified by enlarging at about 300 times. Then, the area occupied by the single fiber that is completely divided into the constituent components is obtained, and a value obtained by dividing this area by the mother area and multiplying by 100 is defined as a division ratio.

  The ultrafine fiber layer is preferably formed by preparing a fiber web containing 50 mass% or more of the above-mentioned split type composite fiber and subjecting it to an entanglement treatment. Here, the ultrafine fiber layer is defined by the ratio of the split-type conjugate fiber before hydroentanglement, when the split-type conjugate fiber is not completely divided into each component as described above, This is because it may be difficult to determine the ratio. The split composite fiber is more preferably contained in the fiber web in an amount of 60 mass% or more, and still more preferably 70 mass% or more. When the ratio of the split-type composite fibers is less than 50 mass% in the fiber web before hydroentanglement, the ratio of ultrafine fibers decreases, and a good wiping effect may not be obtained. Preferably, the ultrafine fiber layer is formed by subjecting a fiber web made of only split-type composite fibers to hydroentanglement treatment.

  Non-split composite fibers include natural fibers such as cotton, pulp and hemp, recycled fibers such as viscose rayon, solvent-spun rayon and copper ammonia rayon, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polybutylene. One or more fibers selected from polyester fibers such as succinate and polylactic acid, polyamide fibers such as nylon 6 and nylon 66, polyolefin fibers such as polyethylene and polypropylene, acrylic fibers and the like may be used. However, if the fineness of fibers other than these split-type composite fibers becomes too large, there is a large amount of liquid remaining on the target surface and there is a possibility that the wiping property may be lowered. Therefore, the fineness is preferably 2.5 dtex or less.

Basis weight of the microfiber layer is more preferably be at 5 g / ^{m 2} or more 100 g / ^{m 2} or less is preferable, 5 g / ^{m 2} or more 40 g / ^{m 2} or less. When the basis weight of the ultrafine fiber layer is less than 5 g / m ² , the texture of the laminated sheet may be deteriorated, and the dirt wiping performance may be deteriorated. When the basis weight of the ultrafine fiber layer exceeds 100 g / m ² , the water absorption measured by the dropping method according to JIS-1096 6.26.1 A of the laminated sheet may be lowered. The basis weight of the ultrafine fiber layer here refers to a fiber web before hydroentanglement treatment containing split-type composite fibers even if the hydrophilic fibers move to the ultrafine fiber layer to some extent during the hydroentanglement treatment, or even if the fibers drop off somewhat. It can be considered that the basis weight is almost the same. Therefore, it should be noted that the basis weight of the ultrafine fiber layer of the laminated sheet may be represented by the basis weight of the fiber web including the split type composite fibers before the hydroentanglement treatment.

  The ultrafine fiber layer is formed by laminating a fiber web containing split-type composite fibers on both surfaces of a hydrophilic nonwoven fabric and subjecting the split-type composite fibers to a hydroentanglement treatment to split the split-type composite fibers. Below, the formation method of an ultrafine fiber layer is demonstrated with the method of manufacturing the lamination sheet of this invention.

  In the laminated sheet of the present invention, a laminated body is produced by laminating a fiber web containing 50 mass% or more of split-type composite fibers on both surfaces of the hydrophilic nonwoven fabric, and the laminate is subjected to hydroentanglement treatment to obtain a split-type composite. It is manufactured by splitting the fibers to obtain ultrafine fibers having a fineness of 0.9 dtex or less and integrating the hydrophilic nonwoven fabric and the ultrafine fiber layer.

  The configuration of the hydrophilic nonwoven fabric is as described above. The hydrophilic nonwoven fabric may be subjected to hydroentanglement treatment to entangle the fibers before laminating the fiber web.

  The fiber web containing the split type composite fibers is a card web, an air lay web, a wet paper web, a spunbond web, or a meltblown web, which is composed of only the split type composite fibers or a mixture thereof with other fibers. The preferred basis weight of the fiber web and the preferred mixing ratio of the split composite fibers are as described above.

Laminate formed by laminating a fiber web to the hydrophilic nonwoven fabric preferably has a basis weight within the range of 20 g / ^{m 2} or more 380 g / ^{m 2} or less, more preferably, 30 g / ^{m 2} or more 120 g / m ^It has a basis weight in the range of ² or less, and more preferably has a basis weight in the range of 30 g / m ² or more and 95 g / m ² or less. When the basis weight of the laminate is less than 20 g / m ² , the texture of the finally obtained laminate sheet tends to be inferior. If the basis weight exceeds 380 g / m ² , the handleability may be lowered when the laminated sheet is used as a wiper, and the cost is increased.

  Next, the laminated body is placed on the transport support, and a water stream is jetted onto one or both sides of the laminated body to perform a hydroentanglement process. At this time, the split composite fiber is split to form an ultrafine fiber layer, and the ultrafine fiber layer and the hydrophilic nonwoven fabric (hydrophilic fiber layer) are integrated by interlacing of the fibers to obtain a laminated sheet. . The hydroentanglement treatment conditions can be appropriately set according to the basis weight of the laminate and the desired splitting degree of the split-type conjugate fiber. For example, from a nozzle in which orifices having a hole diameter of 0.05 mm or more and 0.5 mm or less are provided at intervals of 0.5 mm or more and 1.5 mm or less, a water flow with a water pressure of 2.5 MPa or more and 10 MPa or less is respectively applied from the front and back sides of the laminate. It is good to inject 1 to 4 times.

  The laminated sheet of the present invention is obtained by subjecting the hydroentangled laminate to a drying treatment. The drying process may be performed as a thermal bonding process when the ultrafine fiber layer includes a thermally adhesive ultrafine fiber. The drying process (or heat bonding process) is performed using a hot air spraying machine, a hot roll processing machine, a hot embossing machine, or the like. The heat treatment temperature when heat-adhering the heat-adhesive ultrafine fibers is equal to or higher than the melting point or softening point of the heat-bonding component, and is equal to or lower than the melting point of the fiber having the lowest melting point among other fibers constituting the laminated sheet −10 ° C. Or less (melting point of fiber having the lowest melting point among other fibers constituting the laminated sheet −15 ° C.) or less. By adjusting the heat treatment temperature to such a temperature range, it is flexible as a whole, and does not damage the target surface when rubbed, and the desired effects of the present invention (improvement in water absorption and wiping, liquid It is possible to obtain a laminated sheet that maximizes (remaining reduction).

  The laminated sheet of the present invention thus obtained has a three-layer structure in which the ultrafine fiber layer is located on both surfaces of the hydrophilic fiber layer, and is measured by a dropping method according to JIS-1096 6.26.1 A. It is excellent in water absorption, and the water absorption speed measured by the birec method according to JIS-1096 6.26.1 B is 65 mm / 10 min or more, preferably 100 mm / 10 min or more in the machine direction (MD direction). It will be expensive. The excellent water absorption by the dropping method is that a part of the water droplet is located in the inter-fiber space of the ultrafine fiber layer and is in direct contact with the hydrophilic fiber layer or due to the capillary phenomenon of the ultrafine fiber, This is considered to be due to being drawn into the hydrophilic fiber layer. It is considered that the water absorption rate by the Bilec method is high because water is rapidly drawn in by the capillary phenomenon in the ultrafine fiber layer, and the drawn water quickly moves from the ultrafine fiber layer to the hydrophilic fiber layer. Thus, the laminated sheet of the present invention exhibits high water absorption due to the synergistic action of the ultrafine fiber layer and the hydrophilic fiber layer.

  The laminated sheet of the present invention is preferably used as a wiper. When used as a wiper, it can be used as a dry wiping nonwoven fabric by attaching liquid paraffin or the like as necessary.

  Moreover, the laminated sheet of the present invention can be used as a wettable wiper by adhering with a wetting agent such as water, alcohol, surfactant, or cosmetics by a method such as impregnation, spraying or coating, as necessary. . When used as a wettable wiper, it is preferable to contain a wetting agent in the range of 50 to 300 parts by mass in 100 parts by mass of the laminated sheet.

  Alternatively, the use of the laminated sheet of the present invention is not necessarily limited to the use of wiping off the dirt on the target surface, for example, for uniformly spreading a liquid oily material (eg, a polishing agent) dropped on the target surface. It may be used as a coating sheet. In that case, the laminated sheet of the present invention spreads the oily material thinly and evenly while removing excess oily material, and at the same time, wipes off dirt or water adhering to the target surface if necessary. Therefore, the thin film of the oily material can be satisfactorily formed on the target surface.

  The laminated sheet of the present invention will be described in detail with reference to examples. The thickness of the nonwoven fabric, the splitting ratio in the ultrafine fiber layer, the liquid remaining property, the wiping property, the single fiber dropping property, the water absorption rate, the water absorption property and the liquid retention property were measured as follows.

[Thickness]
Using a thickness measuring machine (trade name: THICKNESS GAUGE model CR-60A, manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.), measurement was performed with a load of 2.94 cN per 1 cm ^{2 of} the sample.

[Split rate]
The laminated sheets were bundled so that the machine direction was a cross-section so that no space was created, and was magnified 300 times with an electron microscope and photographed arbitrarily at three locations. In the photograph taken, the area obtained by subtracting the area occupied by fibers that are not split-type composite fibers such as hydrophilic fibers from the entire area was defined as the mother area for determining the split ratio. Next, the area occupied by the single fibers that were completely divided into the constituent components was obtained, and the area divided by the mother area was multiplied by 100 to obtain the division ratio.

[Liquid residue]
A sample was prepared by cutting the laminated sheet so that the machine direction × width direction was 20 cm × 15 cm, and 200 parts by mass of water was impregnated with 100 parts by mass of the sample to prepare a wet wiper. The wet wiper was folded in four and reciprocated three times on a clean glass plate (30 cm × 50 cm), and then water droplets adhering to the glass surface were visually observed and evaluated in the following five stages.
○: There is no liquid residue, and there is no scale even when dried.
○ to Δ: There is a little liquid residue, but water droplets are small, and scale does not stand out even when dried.
Δ: There are liquid residues in some places, and there is little liquid residue, but some water stains can be confirmed when dried.
Δ to X: There is liquid residue, water droplets are large, and scales can be confirmed when dried.
X: There are many liquid residues, water droplets are quite large, and scales are noticeable when dried.

[Wipeability]
A sample was prepared by cutting the laminated sheet so that the machine direction × width direction was 20 cm × 15 cm. This sample was used in a dry state (DRY) or in a wet state (WET) after impregnating 200 parts by weight of water with respect to 100 parts by weight of the sample.
Next, when a square frame is drawn with oil-based ink with a size of 10 cm × 10 cm at the center of a glass plate (30 cm × 50 cm), and 1) the wiping property of water-based dust is evaluated at the center of the frame. In addition, 5 g of ink is dropped, and 2) when wiping properties of oil-based dust are evaluated, pseudo dust mixed with 95: 5 by mass ratio of Daphne Mechanic Oil 46 and 12 kinds of JIS dust is dropped, In any case, dust was uniformly applied in the frame with a brush having a width of 45 mm.
Fold the DRY or WET sample in four into a square shape of 10cm x 7.5cm, place this dust so that the side of 10cm is aligned with the frame drawn with magic, and make three reciprocations on the dust to remove dirt. The remaining condition was visually observed to evaluate the wiping property. For both water-based dust and oil-based dust, the wiping property was evaluated in the following five stages.
○: No dirt remains on the glass surface.
○ to Δ: A small amount of dirt remains on the glass surface.
Δ: A small amount of dirt remains on the glass surface.
Δ to ×: A large amount of dirt remains on the glass surface.
X: Dirt on the glass surface is not removed.

[Single fiber shedding]
The laminated sheet is cut so that the machine direction × width direction has a size of 30 cm × 20 cm to prepare a sample, which is folded into four (machine direction: about 15 cm, width direction: about 10 cm), and has a size of 30 cm × 50 cm. The area of the short side 10 cm × long side 30 cm on the glass surface is continued for 5 minutes from the short side of the glass surface to the opposing short side so that the direction parallel to the width direction of the nonwoven fabric is the traveling direction. The state of the single fibers remaining on the glass surface after reciprocating was visually observed and evaluated in the following four stages.
(Double-circle): The fallen single fiber was not present at all or almost.
A: A few pieces of shed fibers remained in the vicinity of the short side of the glass surface.
(Triangle | delta): The fallen single fiber remained quite near the short side of the glass surface.
X: Dropped single fibers remained considerably near the short side and the long side of the glass surface.

[Water absorption speed, water absorption]
The water absorption rate was evaluated according to the Bayrec method according to JIS-1096 6.26.1 B, and the water absorption was evaluated according to the dropping method according to JIS-1096 6.26.1 A.

[Sample 1]
As a split type composite fiber (A) containing a modified vinyl alcohol resin, the first component (modified vinyl alcohol resin component) is an ethylene-vinyl alcohol copolymer (ethylene content 38 mol%, vinyl alcohol content 62 mol%). A 16-split composite fiber having a fiber cross section of FIG. 1B having a fineness of 3.3 dtex and a fiber length of 38 mm was prepared using a polypropylene resin as the second component. On the other hand, as a split type composite fiber (B) containing a thermal adhesive component, the first component is a high-density polyethylene resin and the second component is a polyethylene terephthalate resin, and the fineness is 2.2 dtex and the fiber length is 51 mm. An 8-split composite fiber (B1) having a fiber cross section was prepared. Next, the split type composite fiber (A) and the split type composite fiber (B1) are mixed at a ratio of 6: 4 (mass ratio), and the basis weight is about 10 g / m ² using a parallel card machine. Was made.

As the hydrophilic nonwoven fabric, a thermocompression bonded nonwoven fabric (trade name: Taiko TCF, manufactured by Futamura Chemical Co., Ltd.) having a weight per unit area of 20 g / m ² , which is made of rayon short fibers obtained by the viscose method and having a point bond region, was prepared. The point bond region is formed by bonding the fibers together by melting a methylolated derivative of cellulose xanthate. In the nonwoven fabric used, the point bond regions are provided at a rate of about 20 pieces / cm ² , It accounted for about 25%. A split composite fiber web was laminated on both sides of this hydrophilic fiber nonwoven fabric to obtain a laminate having a basis weight of about 40 g / m ² . This laminate was placed on a plain weave carrier support having a warp wire diameter of 0.2 mm and a weft wire diameter of 0.2 mm, and an orifice having a pore diameter of 0.12 mm on the laminate. Is injected once from a nozzle arranged in a straight line in the width direction of the laminated body at intervals of 1 mm, and a water flow of 2.5 MPa is jetted twice, and a water flow of 4 MPa is jetted twice from the same nozzle. Treated.

  Next, the laminate subjected to the hydroentanglement treatment is subjected to heat treatment simultaneously with drying using a hot air processing machine set at a temperature of 140 ° C., so that the split type composite fiber (B1) is split and formed. The fibers contained in the ultrafine fiber layer were adhered to each other by the heat-bonding component constituting the conductive ultrafine fiber and / or the split-type composite fiber (B1), to obtain the laminated sheet of the present invention.

[Sample 2]
A laminated sheet was prepared according to the same procedure as the sample 1 except that the basis weight of the fiber web containing the split type composite fibers was about 12.5 g / m ² and the basis weight of the laminate was about 45 g / m ^2. Produced.

[Sample 3]
A laminated sheet was produced according to the same procedure as the production procedure of Sample 1 except that the basis weight of the fiber web containing the split-type composite fibers was about 15 g / m ² and the basis weight of the laminate was about 50 g / m ² . .

[Sample 4]
A laminated sheet was prepared according to the same procedure as that of Sample 1 except that the basis weight of the fiber web containing the split composite fibers was about 17.5 g / m ² and the basis weight of the laminate was about 55 g / m ^2. Produced.

[Sample 5]
A fiber web containing split composite fibers has a basis weight of about 7.5 g / m ² and has the same configuration as the nonwoven fabric used in Sample 1 as a hydrophilic nonwoven fabric, and has a basis weight of 40 g / m ² Then, a laminated sheet was produced according to the same procedure as that of Sample 1 except that the basis weight of the laminated body was about 55 g / m ² .

[Sample 6]
A long-fiber non-woven fabric made of cupra as a hydrophilic non-woven fabric, having a basis weight of about 25.5 g / m ² and including a fiber entangled region (trade name Bencott SF253: Ozu) A laminated sheet was produced in accordance with the same procedure as that of Sample 1 except that Sangyo Co., Ltd. was used.

[Sample 7]
The split-type conjugate fibers (A) and (B1) used to prepare Sample 1 are mixed at a ratio of 6: 4 (mass ratio), and the basis weight is about 40 g / m ² using a parallel card machine. A card web was prepared. This card web was subjected to hydroentanglement treatment and heat treatment under the same conditions as those employed in the preparation of Sample 1 to obtain hydroentangled nonwoven fabric.

[Sample 8]
Only the hydrophilic nonwoven fabric used to prepare Sample 1 was subjected to the evaluation test.

[Sample 9]
Instead of the hydrophilic non-woven fabric, a procedure similar to that for preparing Sample 1 was used except that a parallel card web made of viscose rayon having a fineness of 1.7 dtex and a fiber length of 44 mm and having a basis weight of about 20 g / m ² was used. A laminated sheet was prepared.

[Sample 10]
As the split-type composite fiber (B) containing a thermal adhesive component, the first component is a high-density polyethylene resin to which a hydrophilizing agent is added, and the second component is a polypropylene resin. The fineness is 2.2 dtex and the fiber length is 51 mm. A 16-split composite fiber (B2) having a fiber cross section (b) was prepared. The hydrophilizing agent is a polyglycerin fatty acid ester which is an ester compound of polyglycerin having a polymerization degree of 4 and oleic acid (unsaturated fatty acid having 17 carbon atoms), and a masterbatch (kneaded by Riken Vitamin Co., Ltd.) Using the product name RIQUEMASTER EAR-2), it was added so as to be contained by 2.4 mass% in the polyethylene resin. Next, the split type composite fiber (A) and the split type composite fiber (B2) are mixed at a ratio of 6: 4 (mass ratio), and the basis weight is about 15 g / m ² using a parallel card machine. Was made. A laminated sheet was produced in accordance with the same procedure as that of Sample 1 except that the same nonwoven fabric used in Sample 6 was used as the hydrophilic nonwoven fabric, and the basis weight of the laminate was about 55 g / m ² .

[Sample 11]
As another split type composite fiber (C) that is neither the split type composite fiber (A) nor (B), the first component is nylon 6 resin and the second component is polyethylene terephthalate resin, the hollow ratio is 20%, and the fineness is 3. A 16-split composite fiber having 3 dtex and a fiber length of 51 mm was prepared. Moreover, the split-type composite fiber (B1) used for producing the sample 1 was prepared as the split-type composite fiber (B) containing the thermal bonding component. Next, the split type composite fiber (C) and the split type composite fiber (B) are mixed at a ratio of 6: 4 (mass ratio), and the basis weight is about 12 g / m ² using a parallel card machine. Was made. A laminated sheet was produced according to the same procedure as that for producing Sample 1, except that the nonwoven fabric used for producing Sample 1 was used as the hydrophilic nonwoven fabric, and the basis weight of the laminate was about 44 g / m ² .

[Sample 12]
A card web composed of split-type conjugate fibers according to the same procedure as that of Sample 10, except that two types of split-type conjugate fibers used to make Sample 10 were used and the basis weight was 18 g / m ^2. Was made. Moreover, the hydroentangled nonwoven fabric which consists of rayon fiber was prepared as a hydrophilic nonwoven fabric. The hydrophilic nonwoven fabric is a card web having a basis weight of 15 g / m ² using a parallel card machine using rayon fibers (manufactured by Daiwabo Rayon Co., Ltd.) having a fineness of 1.7 dtex and a fiber length of 44 mm. Placed on an 80-mesh plain weave carrier having a diameter of 0.2 mm and a weft wire diameter of 0.2 mm, and orifices with a hole diameter of 0.12 mm are arranged in a straight line in the width direction of the web at intervals of 1 mm A water flow having a water pressure of 1.5 MPa was jetted once from the nozzle, and the web was turned over and the water flow having a water pressure of 1.5 MPa was jetted from the same nozzle once. The laminated sheet is laminated in accordance with the same procedure as the sample 1 except that the card web made of split-type composite fibers is laminated on both surfaces of the hydrophilic nonwoven fabric, and the basis weight of the laminated body is about 51 g / m ^2. A sheet was produced.

[Sample 13]
As a split type composite fiber (B) containing a thermal bonding component, the first component is a high-density polyethylene resin and the second component is a polypropylene resin, and the fiber cross section of FIG. 1B with a fineness of 2.2 dtex and a fiber length of 51 mm. 16 split type composite fiber (B3) having The split-type conjugate fiber (A) and the split-type conjugate fiber (B3) used to prepare the sample 1 are mixed at a ratio of 6: 4 (mass ratio), and the basis weight is about A card web of 18 g / m ² was produced. A laminated sheet is prepared according to the same procedure as the sample 1 except that the same non-woven fabric used for preparing the sample 12 is prepared as the hydrophilic non-woven fabric, and the basis weight of the laminate is about 51 g / m ^2. did.

[Sample 14]
A laminated sheet is produced according to the same procedure as the sample 12 except that the basis weight of the card web made of split composite fibers is about 12 g / m ² and the basis weight of the hydrophilic nonwoven fabric is about 25 g / m ^2. did.

The evaluation results of Samples 1 to 14 are shown in Table 1.

  Samples 1 to 6 were all excellent in liquid residue, wiping property, and water absorption, and also had few shed fibers. On the other hand, the hydrophilic non-woven fabric itself (Sample 8) was inferior in wiping property and had a lot of dropped fibers. Furthermore, since each of Samples 1 to 6 has a water absorption rate greater than that of Sample 8, and Sample 7 produced using only split-type conjugate fibers has a water absorption rate of 0, the ultrafine fiber layer and the hydrophilic layer It can be said that the water absorption speed can be drastically increased by using the nonwoven fabric together. Sample 9 using a fiber web in which the fibers were not substantially bonded or entangled in place of the hydrophilic nonwoven fabric had a large amount of liquid residue, and was also inferior in terms of wiping property as compared with samples 1-6. This indicates that the use of a nonwoven fabric in which fibers are fixed to some extent contributes to the suppression of the exposure of hydrophilic fibers, whereby a sheet with little liquid residue and good wiping properties can be obtained. ing.

  From the evaluation results of Samples 1 to 3, it is possible to compare the performance when the hydrophilic fiber layer is composed of the same nonwoven fabric and the basis weight of the ultrafine fiber layer is changed. The greater the basis weight of the ultrafine fiber layer, the lower the water absorption evaluated by the dropping method, but there are many extrafine fibers in the vicinity of the sheet surface, so there is little liquid residue, and the absolute amount of heat-adhesive ultrafine fibers Therefore, the amount of fibers that fall out decreases. Although Sample 5 showed a high water absorption rate by increasing the basis weight of the hydrophilic fiber layer, the wiping property was slightly lower than Sample 1 because the absolute amount of ultrafine fibers was small. Sample 6 was obtained by using a long-fiber nonwoven fabric as a hydrophilic fiber layer, and had a high water absorption rate, excellent water absorption, good wiping property, and few single fibers falling off.

  Samples 10 and 12 to 14 are sheets prepared using fibers made of a combination of polypropylene / polyethylene as split-type composite fibers that form heat-adhesive ultrafine fibers. Samples 10, 12, and 14 in which a hydrophilizing agent was contained in polyethylene exhibited a high water absorption rate because of high splitting ratio and high hydrophilicity of the fibers themselves. The sample 14 has substantially the same basis weight as the sample 12, but the basis weight of the hydrophilic non-woven fabric is larger and the basis weight of the polarized fine fiber layer is small. Due to the small amount of fibers, there were a few more dropped fibers. In Sample 10, the hydrophilic fiber layer was a long-fiber non-woven fabric, so that the number of dropped fibers was small. Sample 13 had a slightly lower water absorption rate than Sample 12 having substantially the same configuration because polyethylene did not contain a hydrophilizing agent. Since sample 11 used split type composite fiber made of a combination of nylon 6 / polyethylene terephthalate instead of split type composite fiber (A), the liquid residue, wipeability and water absorption of sample 11 were the same as those of sample 1. Although it was a little inferior compared, it was a level with no practical problem.

  The laminated sheet of the present invention has high water absorption and has a feature that there is little liquid residue when a wet object is wiped or when an object is wiped with the sheet wet. It can be suitably used for objects such as office automation equipment, glasses, automobiles, kitchens and shoes, as well as for objectives and interpersonal wipers that wipe off dirt and oily dirt adhering to people from the target surface. Since the amount of dust is small, it can be suitably used for a wiper used in a clean room.

An example of the fiber cross section in the split type composite fiber of this invention is shown.

Explanation of symbols

1 1st component 2 2nd component

Claims (20)

A laminated sheet in which ultrafine fiber layers containing ultrafine fibers are laminated on both sides of a hydrophilic fiber layer containing hydrophilic fibers,
The hydrophilic fiber layer is composed of short fibers, and includes a point bond region where the hydrophilic fibers are bonded to each other,
The ultrafine fiber layer includes an ultrafine fiber having a fineness of 0.9 dtex or less obtained by splitting a split type composite fiber composed of a plurality of resin components,
A laminated sheet in which a hydrophilic fiber layer and an ultrafine fiber layer are integrated by hydroentanglement.   The laminated sheet according to claim 1, wherein the hydrophilic fiber layer includes regenerated cellulose fibers, and the regenerated cellulose fibers are self-adhering to form the point bond region. The laminated sheet according to claim 1 or 2, wherein the hydrophilic fiber layer is composed of short rayon fibers. A laminated sheet in which ultrafine fiber layers containing ultrafine fibers are laminated on both sides of a hydrophilic fiber layer containing hydrophilic fibers,
Before the hydrophilic fiber layer is integrated with the ultrafine fiber layer, it is a layer including a fiber entangled region in which hydrophilic fibers are entangled with each other,
The ultrafine fiber layer includes an ultrafine fiber having a fineness of 0.9 dtex or less obtained by splitting a split type composite fiber composed of a plurality of resin components,
A laminated sheet in which a hydrophilic fiber layer and an ultrafine fiber layer are integrated by hydroentanglement. The laminated sheet according to claim 4 , wherein the hydrophilic fiber layer includes regenerated cellulose long fibers, and the cellulose long fibers are entangled to form the fiber entangled region before being integrated with the ultrafine fiber layer. The laminated sheet according to any one of claims 1 to 5 , wherein the ultrafine fiber layer is obtained by subjecting a fiber web containing 50 mass% or more of the split composite fibers to hydroentanglement treatment. The ultrafine fiber layer contains a modified vinyl alcohol resin having a fineness of 0.9 dtex or less obtained by splitting a split type composite fiber (A) composed of a component containing a modified vinyl alcohol resin and at least one other resin component The laminated sheet according to any one of claims 1 to 6 , comprising extra fine fibers. The ultrafine fiber layer is a thermoadhesive ultrafine fiber having a fineness of 0.9 dtex or less obtained by splitting a split type composite fiber (B) comprising a component containing a thermoadhesive resin and at least one other resin component. The laminated sheet according to any one of claims 1 to 7 , wherein the fibers are thermally bonded to each other by heat-adhesive ultrafine fibers. The ultrafine fiber layer contains a split composite fiber (A) composed of a component containing a modified vinyl alcohol resin and at least one other resin component in a proportion of 40 mass% to 90 mass%, and includes a heat-adhesive resin. It is obtained by subjecting a fiber web containing a component and a split type composite fiber (B) composed of at least one other resin component at a ratio of 10 mass% to 60 mass% to hydroentanglement treatment and thermal bonding treatment. The laminated sheet according to any one of claims 1 to 8 . The laminated sheet according to claim 7 or 9 , wherein the modified vinyl alcohol resin is a resin having a vinyl alcohol content in a range of 50 mol% to 70 mol%. In the split composite fiber (A), the component containing the modified vinyl alcohol resin is a component containing an ethylene-vinyl alcohol copolymer resin, and at least one of the other resin components is a component containing a polyolefin resin. The laminated sheet according to claim 7 or 9 . The basis weight of the microfiber layer is in the range of 5 g / ^{m 2} or more 40 g / ^{m 2} or less, the laminated sheet according to any one of claims 1 to 11. The basis weight of the hydrophilic fiber layer is in the range of 180 g / ^{m 2} or less 10 g / ^{m 2} or more, the laminated sheet according to any one of claims 1 to 12. The laminated sheet according to any one of claims 1 to 13 , wherein a water absorption speed measured by a birec method according to JIS-1096 6.26.1 B is 65 mm / 10 min or more. Made staple fibers include hydrophilic fibers than 20 mass%, and the splittable conjugate fibers on both surfaces of a hydrophilic nonwoven fabric containing point bond area of the hydrophilic fibers is adhered by laminating a fibrous web containing more than 50 mass% Obtaining a laminate, and subjecting the laminate to hydroentanglement, splitting the split composite fiber to obtain ultrafine fibers having a fineness of 0.9 dtex or less and integrating the hydrophilic nonwoven fabric and the fiber web A method for producing a laminated sheet, comprising: The manufacturing method according to claim 15 , wherein the hydrophilic nonwoven fabric includes a regenerated cellulose fiber, and the regenerated cellulose fibers are self-adhered to form the point bond region. Laminating a fiber web containing 50 mass% or more of split-type composite fibers on both sides of a hydrophilic nonwoven fabric containing 20 mass% or more of hydrophilic fibers and including a fiber entanglement region in which hydrophilic fibers are entangled with each other; and
The laminated body is subjected to hydroentanglement treatment, and split-type composite fibers are split to obtain ultrafine fibers with a fineness of 0.9 dtex or less, and the hydrophilic nonwoven fabric and fiber web are integrated.
A method for producing a laminated sheet, comprising: The hydrophilic nonwoven fabric comprises a regenerated cellulose fiber, a nonwoven fabric of regenerated cellulose fibers form a port Intobondo area with self-adhesive, a nonwoven fabric obtained is subjected to hydroentangling process, according to claim 15 or 17 The manufacturing method as described in. The manufacturing method according to any one of claims 15 to 18 , wherein the split-type conjugate fiber is a split-type conjugate fiber having at least one component containing a modified vinyl alcohol resin as a component. A wiper comprising the laminated sheet according to any one of claims 1 to 14 .

Images