JP2017179652A - Sheet-like material for water absorption roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet-like material for a water absorption roll, having both excellent water absorption performance and abrasion resistance.SOLUTION: Provided are: a sheet-like material for a water absorption roll formed by including a polymeric elastomer, containing polyurethane as a main component, in a nonwoven fabric composed of entangled fiber bundles of short fiber containing ultra-thin hollow fiber having an average fiber diameter of 0.05 to 10 μm, where the ultra-thin follow fiber has 2 to 60 hollow parts on a fiber cross-section, and the ultra-thin hollow fiber and the polymeric elastomer containing polyurethane as a main component for fixing the ultra-thin hollow fiber are present on both surfaces of the sheet-like material; the sheet-like material for a water absorption roll, where a hollow ratio of the ultra-thin hollow fiber is preferably 30 to 80%; and the sheet-like material for water absorption roll, where the ultra-thin hollow fiber preferably comprises a polyester-based polymer and the polyurethane is a polycarbonate-based urethane.SELECTED DRAWING: None

Description

  The present invention relates to a sheet-like material that has excellent water absorption and is suitably used for a water absorption roll.

  2. Description of the Related Art Conventionally, in the production of steel, films, nonwoven fabrics, and the like, a method using a water absorption roll is used for wiping off adhered water or oil in processes such as cleaning, chemical treatment and coating. Wiping using a water-absorbing roll is widely used because it can reduce energy required for a drying process or the like if it is water or the like, and can suppress defects in a subsequent process by high wiping performance.

  As the water-absorbing roll, a water-absorbing roll composed mainly of a sheet-like material composed of ultrafine fibers is mainly used. The reason why the sheet-like material made of ultrafine fibers is applied to the water-absorbing roll is that by applying the ultrafine fibers, high water-absorbing performance is exhibited by the capillary effect due to fine voids formed in the sheet-like material.

  In order to improve the water absorption performance of such a sheet for water absorption rolls, several studies have been made so far.

  Specifically, a sheet-like material in which a polymer elastic body is imparted to a nonwoven fabric of long hollow fibers has been proposed (see Patent Document 1). However, in this proposal, since the hollow fibers are long fibers, the number of fiber cross-sections having hollow portions in the sheet-like material is small, and the effect of improving the water absorption performance by applying the hollow fibers is small. Moreover, since the fiber diameter of the hollow fiber is as large as 16.5 to 18.8 μm (described in the examples), the gap formed between the ultrafine fibers in the sheet-like material becomes large, so that the water absorption performance uses ultrafine fibers. It is thought that it is inferior to what we did.

  Separately, a fibrous sheet in which a non-woven fabric entangled with lotus root-like porous fibers is filled with a polymer elastic body has been proposed (see Patent Document 2). However, in this proposal, lotus root fibers are obtained by mixed spinning, and the size of the hollow portion of the fibers varies greatly, resulting in a non-uniform sheet. Therefore, the water absorption performance differs depending on the position of the sheet-like material, and there is a problem that unevenness occurs in wiping. Further, since the lotus root-like fiber is developed after the polyurethane elastomer is applied to the nonwoven fabric, the adhesion between the fiber and the polyurethane elastomer is insufficient, and it is considered that the wear resistance is low.

  In addition, although it is an artificial leather intended for weight reduction, a sheet-like material made of ultrafine hollow fibers and an elastic polymer has been proposed (see Patent Document 3). However, in this proposal, although not intended for the water absorbing roll, when applied to the water absorbing roll, the surface of the sheet-like material is raised and becomes only fibers, and is not fixed to the polymer elastic body. Therefore, when used as a water absorbing roll, there is a possibility that the wear resistance is insufficient. In addition, there is a possibility that the grinding powder adheres to the raising process, and the problem is that the grinding powder adheres to the treated product, and the grinding powder is clogged in the voids in the sheet-like material, thereby reducing the water absorption performance. There is.

JP, 2015-151632, A Japanese Patent Laid-Open No. 50-10023 International Publication No. 2016/031624

  Then, the objective of this invention is providing the sheet-like object for water absorption rolls which combined the high water absorption performance and abrasion resistance in view of the subject of the said prior art.

  That is, the present invention is to solve the above-mentioned problems, and the water-absorbing roll sheet-like product of the present invention is a short fiber comprising ultrafine hollow fibers having an average fiber diameter of 0.05 μm or more and 10 μm or less. Is a sheet-like material containing a polymer elastic body mainly composed of polyurethane in a nonwoven fabric in which fiber bundles are intertwined, and has 2 to 60 hollow portions in the fiber cross section of the ultrafine hollow fiber. And a sheet-like material for a water-absorbing roll in which a polymer elastic body mainly composed of polyurethane for fixing the ultrafine hollow fiber and the ultrafine hollow fiber is present on both surfaces of the sheet-like material. .

  According to a preferred embodiment of the present invention, the hollow ratio of the ultrafine hollow fiber is 30 to 80%.

  According to the preferable aspect of this invention, the compression rate in the thickness direction of the said sheet-like material is 1% or more and 20% or less.

  According to a preferred aspect of the present invention, the ultrafine hollow fiber is made of a polyester polymer.

  According to a preferred embodiment of the present invention, the polyurethane is a polycarbonate-based polyurethane.

  According to the present invention, in addition to the capillary effect obtained by the fine voids in the sheet-like material formed by entanglement of the ultrafine fibers, a hollow portion is formed in the fiber cross section of the ultrafine fibers, and the short fibers By entanglement in the state, a large number of ultrafine hollow fiber cross sections are distributed in the sheet-like material, whereby a water-absorbing roll sheet-like material having superior water absorption performance as compared with conventional products is obtained.

  In addition, the presence of a polymer elastic body mainly composed of polyurethane that fixes the ultrafine hollow fibers and the ultrafine hollow fibers on both surfaces of the sheet-like material, thereby increasing the thickness of the sheet-like material with the conventional surface raised or by grinding, etc. Compared with the adjusted sheet-like material, the water-absorbing roll sheet-like material of the present invention is fixed with a polymer elastic body mainly composed of polyurethane up to the ultrafine hollow fibers on the surface of the sheet. Since there is no adhesion of grinding powder that is sometimes generated, it can be suitably used for a water absorbing roll.

  Next, the sheet-like material for water-absorbing roll of the present invention and the manufacturing method thereof will be specifically described.

  The water-absorbing roll sheet material of the present invention is mainly composed of polyurethane in a nonwoven fabric in which short fiber bundles composed of ultrafine hollow fibers having an average fiber diameter of 0.05 μm or more and 10 μm or less are intertwined. It is a sheet-like material containing a polymer elastic body, has 2 to 60 hollow portions in the fiber cross section of the ultrafine hollow fiber, and has ultrafine hollow on both surfaces of the sheet-like material. This is a water-absorbing roll sheet-like material in which a polymer elastic body mainly composed of polyurethane for fixing fibers and the above-mentioned ultrafine hollow fibers is present.

  Examples of the fibers constituting the ultrafine hollow fiber having a hollow portion constituting the water-absorbing roll sheet of the present invention include, for example, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene 2,6-naphthalene dicarboxylate. In addition, various synthetic fibers made of polyester such as polylactic acid, polyamide such as nylon 6, nylon 66, nylon 610, and nylon 12, and polymers such as acrylic, polyethylene, polypropylene, and thermoplastic cellulose can be used. Among these, polyester fibers made of polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and the like are particularly preferably used from the viewpoint of excellent strength, dimensional stability, and wet strength. In addition, from the viewpoint of environmental considerations, fibers obtained from recycled raw materials and plant-derived raw materials can be used, and furthermore, ultrafine fibers of different materials can be mixed.

  Depending on various purposes, inorganic particles such as titanium oxide particles, lubricants, pigments, heat stabilizers, ultraviolet absorbers, conductive agents, heat storage agents, and antibacterial agents are added to the polymer forming the ultrafine hollow fibers. be able to.

  It is important that the average single fiber diameter of the single fibers of the ultrafine hollow fibers constituting the sheet-like material for a water absorbent roll of the present invention is 0.05 to 10 μm. By setting the average single fiber diameter to 10 μm or less, preferably 8 μm or less, more preferably 7 μm or less, fine voids can be formed in the sheet-like material, and excellent water absorption performance due to the capillary effect between the single fibers Is obtained.

  On the other hand, by setting the average single fiber diameter to 0.05 μm or more, preferably 0.7 μm or more, more preferably 1 μm or more, sufficient mechanical strength that can be used as a water absorbing roll can be maintained.

  It is important that the number of hollow portions in the fiber cross section of the ultrafine hollow fiber having a hollow portion forming the sheet-like material for a water absorbing roll of the present invention is 2 to 60. By setting the number of hollow portions to two or more, wall surfaces (supports crossing the fiber cross section) are formed between the hollow portions, so that the rigidity of the ultrafine hollow fiber is improved as compared with the case of one hollow portion. This makes it possible to prevent the hollow portion from being completely crushed and the effects of the present invention from being lost when the water-absorbing roll is compressed.

  When the upper limit of the number of the hollow portions is obtained by removing easily eluting components (polymers), the upper limit is 60, so that the easily eluting polymers can be easily removed. The number of hollow portions is more preferably in the range of 3-40.

  The pore diameter of the hollow portion of the ultrafine hollow fiber is preferably 0.01 to 3 μm. By setting it as this range, the water absorption performance of the water-absorbing roll sheet-like material can be improved due to the capillary effect of the hollow portion of the ultrafine hollow fiber as compared with the normal fiber having no hollow portion.

  The cross-sectional shape of the hollow portion can be a desired shape such as a round shape or a polygonal shape, depending on the purpose, but is preferably a round shape from the viewpoint of the shape stability of the fiber cross section. Moreover, as an arrangement method in the cross section of a hollow part, concentric circle shape, a geometric pattern, etc. can be formed.

  In the present invention, it is important that a bundle of ultrafine hollow fibers (ultrafine hollow fiber bundle) is entangled to form a nonwoven fabric. By entangling the ultrafine bundle, fine voids can be formed in the fiber bundle, and higher water absorption can be obtained.

  It is important that the ultrafine hollow fiber is in the form of a non-woven fabric (extrafine fiber web) in the water-absorbing roll sheet. By setting it as a nonwoven fabric, a uniform space | gap can be formed in the sheet-like material for water absorption rolls, and the sheet-like material for water absorption rolls which can absorb water uniformly is obtained.

  It is important that the nonwoven fabric (ultrafine fiber web) is a short fiber nonwoven fabric. By using a short fiber nonwoven fabric, many fiber cross sections having hollow portions are distributed in the water-absorbing roll sheet material. By absorbing water into the voids in the hollow portion, the water-absorbing roll sheet material has high water absorption. It is possible to obtain

  The fiber length of the short fibers constituting the short fiber nonwoven fabric is preferably 25 to 90 mm. By setting the fiber length to 90 mm or less, a fiber cross section necessary for improving the water absorption performance can be obtained, and by setting the fiber length to 25 mm or more, it has excellent wear resistance and can endure actual use with a water absorption roll. The fiber length is more preferably 35 to 80 mm, and particularly preferably 40 to 70 mm.

  In the ultrafine hollow fiber used in the present invention, the total area of the hollow portion in the fiber cross section is 20 to 80% of the area of the fiber cross section (hereinafter, the ratio of the hollow portion may be referred to as “hollow ratio”). ), More preferably 30 to 80%, still more preferably 40 to 70%. When the hollow ratio is less than 20%, the amount of water absorbed in the ultrafine hollow fiber is reduced, so that it is difficult to obtain the effect of the present invention. When the hollow ratio exceeds 80%, the hollow portion is easily crushed and water absorption is reduced. There is a tendency.

  The water-absorbing roll sheet material of the present invention comprises a polymer elastic body mainly composed of polyurethane. The polymer elastic body is a polymer compound having rubber elasticity that expands and contracts, and examples of the polymer elastic body include polyurethane, SBR, NBR, and an acrylic resin. Moreover, the main component here means that the mass of polyurethane is more than 50 mass% with respect to the mass of the whole polymer elastic body.

  By using a polymer elastic body mainly composed of polyurethane, when a water-absorbing roll is produced, the roll does not easily deform even when compressed, or it follows and deforms when wiping away uneven objects. Effects such as difficulty are obtained. Further, when wiping off water droplets or the like attached to the object to be treated with the water absorbing roll, the water absorbing roll is pressed against the object to be processed, and the surface of the water absorbing roll contacting the object to be processed is compressed. At that time, while the water droplets adhering to the object to be treated are blocked, when the surface of the water absorbing roll leaves the object to be treated, the compression of the water absorbing roll is released. Moisture will be taken up.

  By including a polymer elastic body mainly composed of polyurethane, it is easy to return to its original shape when released from compression, and a water-absorbing roll sheet having excellent water-absorbing performance is obtained.

  Examples of the polyurethane include an organic solvent-based polyurethane used in a state dissolved in an organic solvent, and a water-dispersed polyurethane used in a state dispersed in water, and both can be employed in the present invention.

  As the polyurethane used in the present invention, a polyurethane obtained by a reaction of a polymer diol, an organic diisocyanate and a chain extender is preferably used.

  As the polymer diol, for example, polycarbonate-based, polyester-based, polyether-based, silicone-based, and fluorine-based diols can be adopted, and a copolymer combining these can also be used. There is no problem when wiping off the oil system, but when wiping water or particularly hot water for a long period of time, problems such as deformation of the roll due to hydrolysis of the polyurethane may occur. From this point of view, a polycarbonate-based polymer diol is preferably used as the polymer diol. Thus, the polymer diol can be appropriately selected depending on the liquid to be wiped off, the cost, and the like.

  The polycarbonate diol can be produced by transesterification of alkylene glycol and carbonate, or reaction of phosgene or chloroformate with alkylene glycol.

  Examples of the alkylene glycol include ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, and 1,10-decanediol. Linear alkylene glycol, and branched alkylene glycols such as neopentyl glycol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol and 2-methyl-1,8-octanediol Alicyclic diols such as 1,4-cyclohexanediol, aromatic diols such as bisphenol A, glycerin, trimethylolpropane, and pentaerythritol.

  In the present invention, both polycarbonate-based diols obtained from individual alkylene glycols and copolymerized polycarbonate-based diols obtained from two or more types of alkylene glycols can be used.

  Examples of the polyester diol include polyester diols obtained by condensing various low molecular weight polyols and polybasic acids.

  Examples of the low molecular weight polyol include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, and 2,2-dimethyl-1,3. -Propanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, cyclohexane-1,4-diol And one or more selected from cyclohexane-1,4-dimethanol can be used. Further, addition products obtained by adding various alkylene oxides to bisphenol A can also be used.

  Examples of the polybasic acid include succinic acid, maleic acid, adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, and One or more selected from hexahydroisophthalic acid can be mentioned.

  Examples of the polyether-based diol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and copolymerized diols combining them.

  The number average molecular weight of the polymer diol used in the present invention is preferably 500 to 4000. By making the number average molecular weight preferably 500 or more, more preferably 1500 or more, it is possible to prevent the texture of the sheet-like material from becoming hard. Moreover, the intensity | strength as a polyurethane is maintainable by making a number average molecular weight into 4000 or less, More preferably 3000 or less preferably.

  Examples of the organic diisocyanate include aliphatic diisocyanates such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and xylylene diisocyanate, and aromatic diisocyanates such as diphenylmethane diisocyanate and tolylene diisocyanate. Can also be used in combination. Among them, aromatic diisocyanates such as diphenylmethane diisocyanate are preferably used when importance is attached to durability and heat resistance, and hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and isophorone diisocyanate are preferred when importance is attached to light resistance. Aliphatic diisocyanates are preferably used.

  Examples of the chain extender include amine chain extenders such as ethylenediamine and methylenebisaniline, and diol chain extenders such as ethylene glycol. Moreover, the polyamine obtained by making polyisocyanate and water react can also be used as a chain extender.

  If desired, a crosslinking agent can be used in combination with polyurethane for the purpose of improving water resistance, abrasion resistance, hydrolysis resistance and the like. The cross-linking agent may be an external cross-linking agent added as a third component to the polyurethane, or an internal cross-linking agent that introduces a reaction point that becomes a cross-linked structure in advance in the polyurethane molecular structure may be used. In the present invention, it is preferable to use an internal cross-linking agent from the viewpoint that the cross-linking points can be formed more uniformly in the polyurethane molecular structure and the reduction in flexibility can be reduced.

  As said crosslinking agent, the compound which has an isocyanate group, an oxazoline group, a carbodiimide group, an epoxy group, a melamine resin, a silanol group, etc. can be used. However, if the crosslinking proceeds excessively, the polyurethane tends to harden and the texture of the sheet-like material tends to harden, so that a crosslinking agent having a silanol group is preferably used in terms of the balance between reactivity and flexibility.

  When water-dispersed polyurethane is used in the present invention, it is a preferred embodiment to use an internal emulsifier in order to disperse the polyurethane in water. Examples of the internal emulsifier include cationic internal emulsifiers such as quaternary amine salts, anionic internal emulsifiers such as sulfonates and carboxylates, and nonionic internal emulsifiers such as polyethylene glycol. Any of a combination of a nonionic internal emulsifier and a combination of an anionic and nonionic internal emulsifier can be employed.

  The polymer elastic body used in the present invention may contain an elastomer resin such as polyester, polyamide, and polyolefin, an acrylic resin, and an ethylene-vinyl acetate resin as long as the performance as a binder is not impaired. . The polymer elastic body may contain various additives, for example, pigments such as carbon black, hydrolysis stabilizers such as polycarbodiimide, plasticizers and antistatic agents.

  The content of the elastic polymer can be appropriately adjusted in consideration of the type of polyurethane to be used, the polyurethane production method, texture and physical properties described below. The content of the polymer elastic body is preferably 10% by mass or more and 100% by mass or less, and more preferably 20% by mass or more and 50% by mass or less.

  In the sheet-like material for water-absorbing rolls of the present invention, the surface of the sheet-like material for water-absorbing rolls has a structure in which ultrafine hollow fibers and a polymer elastic body mainly composed of polyurethane for fixing the fine hollow fibers are present. It is important to be.

  A structure in which a polymer elastic body mainly composed of polyurethane for fixing ultrafine hollow fibers and ultrafine hollow fibers exists on both surfaces of the sheet-like material for water-absorbing roll refers to both surfaces of the sheet-like material for water-absorbing roll. Both the ultrafine hollow fiber and the polymer elastic body mainly composed of polyurethane are exposed, and the polymer elastic body mainly composed of polyurethane is adhered to and gripped by the ultrafine hollow fiber.

  The thickness of the conventional water-absorbing roll sheet material is adjusted by grinding with sandpaper or the like. In this case, the surface of the water-absorbing roll sheet material has napped fibers made up of ultrafine fibers, and the polymer There is almost no elastic body. Therefore, in actual use with a water absorbing roll, when pressure or friction is applied to the water absorbing roll, the fibers on the surface of the sheet-like material easily fall off and adhere to the surface of the processed object. In addition, when the sheet-like material is ground, fiber grinding powder is generated. Therefore, if the removal of the grinding powder is insufficient, adhesion to the processed material and fine voids formed in the sheet-like material will occur. It will clog and cause a decrease in water absorption.

  By adopting a structure in which a polymer elastic body mainly composed of polyurethane that fixes the ultrafine hollow fibers and the polyurethane that fixes the ultrafine hollow fibers is present on both surfaces of the water-absorbing roll sheet-like material, as in the present invention, It is possible to solve the problem.

  The thickness of the water-absorbing roll sheet material of the present invention is preferably in the range of 0.5 to 10 mm. By making the thickness 0.5 mm or more, preferably 1 mm or more, and more preferably 1.5 mm or more, when producing a water-absorbing roll, which will be described later, an increase in the number of stacked sheets is prevented and productivity is improved. In addition, when the thickness is 10 mm or less, preferably 8 mm or less, more preferably 6 mm or less, the water-absorbing roll can be sufficiently compressed and a roll having a desired hardness can be obtained.

  The sheet-like material for water-absorbing rolls according to the present invention is a preferred embodiment in which the compressibility in the thickness direction is 1% or more and 20% or less. The compression rate is the thickness reduction rate when a load is applied to the water-absorbing roll sheet material, and the higher the value, the easier it is to collapse. If the compressibility is 20% or less, the sheet for water-absorbing rolls is not easily crushed, and the hollow portion of the ultrafine hollow fiber maintains the form, which is an index for improving the water-absorbing performance.

  Next, the example of the method of manufacturing the sheet-like object for water absorption rolls of this invention is demonstrated.

  As a method for obtaining an ultrafine hollow fiber, two or more thermoplastic resins having different solubility in a solvent or the like are used for a sea component and an island component, and the sea component is dissolved and removed in a subsequent process using a solvent or the like. Sea-island type composite fibers with island components as ultrafine fibers, and peelable type composites in which multiple thermoplastic resins are arranged alternately in a radial or multilayer fashion on the fiber cross-section, and each component is separated into ultrafine fibers by separation. A fiber etc. can be employ | adopted. Specifically, a plurality of measuring plates having a plurality of measuring holes for measuring the sea-island component polymer flow described in Japanese Patent Application Laid-Open No. 2011-174215 and a confluence groove for combining the discharged polymer flows from the plurality of measuring holes By using a composite spinneret capable of forming various cross-sectional shapes by combining the distribution plates having the distribution holes, sea-island type composite fibers can be produced.

  In the ultrafine hollow fiber of the present invention, the distribution holes are arranged in the island component of the sea-island type composite fiber so as to be able to form an eluting middle sea component (meaning an eluting sea component in the island component). Can be achieved. The fiber cross section of the ultrafine hollow fiber generating fiber obtained in this way is because the ultrafine fibers that are island components are present in the sea component and the hollow portion is formed in the ultrafine fibers that are island components. The sea component (Nakaumi component) is arranged. About this ultrafine hollow fiber generation type fiber, by treating by the method described later, the outer sea component is dissolved, the ultrafine fiber which is the island component is expressed, and the inner sea component in the island component is also eluted, A hollow portion is formed on the surface, and an ultrafine hollow fiber can be obtained.

  The nonwoven fabric which comprises the sheet-like material for water absorption rolls of this invention can obtain a nonwoven fabric by the process of producing a composite fiber web, and the process of performing an entanglement process to the composite fiber web. The main component of the polyurethane is before and / or after raising the ultra-fine fiber by dissolving or removing the polymer of the easily-eluting component of the composite fiber from the obtained non-woven fabric or peeling or dividing it by physical or chemical action. A sheet-like material can be obtained through a step of applying the elastic polymer as described above to a nonwoven fabric and substantially solidifying and solidifying the elastic polymer.

  It is important that the ultrafine hollow fiber having a hollow portion constituting the water-absorbing roll sheet-like material of the present invention has 2 to 60 hollow portions in the ultrafine hollow fiber having an average fiber diameter of 0.05 to 10 μm. is there. The formation of the hollow portion is preferably obtained from a precisely controlled sea-island type composite fiber, and in the island component of the sea-island type fiber composed of a sea component and an island component, a further leaching Nakaumi component (a sea component in the island component) ) Is formed, and the Nakaumi component is extracted and removed, so that a more elutable Nakaumi component (sea component in the island component) is formed in the island component, and the Nakaumi component is extracted to have a hollow portion. An ultrafine hollow fiber can be obtained.

  The composite fiber used in the present invention is preferably provided with buckling crimp. This is because by imparting buckling crimp, entanglement between the fibers when the short fiber nonwoven fabric is formed is improved, and high density and high entanglement are possible. In order to impart buckling crimp to the composite fiber, a normal stuffing box type crimper is preferably used, but in order to obtain a preferable crimp retention coefficient in the present invention, the fiber diameter of the composite fiber and the application treatment are performed. It is a preferable aspect to appropriately adjust the number of fibers, the crimper temperature, the crimper load, the indentation pressure, and the like when performing.

  Extraction and removal of the sea component (sometimes referred to as the open sea component) and the sea component in the island component of the composite fiber used in the production of the water-absorbing roll sheet material of the present invention is the elasticity when producing a sheet material. It can be carried out at any stage before or after applying the polymer.

  The water-absorbing roll sheet material of the present invention is obtained by entanglement of short fibers, and the obtained composite fibers are cut by a known method such as a cutter to obtain short fibers.

  As a method for obtaining the nonwoven fabric constituting the sheet for water-absorbing roll of the present invention, as described above, a method of entanglement of a fiber web with a needle punch or a water jet punch, a papermaking method, or the like can be employed. Among them, a method that undergoes a treatment such as a needle punch or a water jet punch is preferably used in order to obtain the above-described ultrafine fiber bundle mode.

  As the nonwoven fabric, a nonwoven fabric and a woven or knitted fabric can be laminated and integrated, and a method of integrating them by a needle punch, a water jet punch or the like is preferably used.

  In the needle used for the needle punching process, the number of needle barbs (cuts) is preferably 1 to 9. By using one or more needle barbs, efficient fiber entanglement becomes possible. On the other hand, by making the needle barb preferably 9 or less, fiber damage can be suppressed.

  The number of composite fibers such as ultrafine hollow fiber generating fibers caught on the barb is determined by the shape of the barb and the diameter of the composite fiber. Therefore, the barb shape of the needle used in the needle punching process has a kick-up of 0-50 μm, an undercut angle of 0-40 °, a throat depth of 40-80 μm, and a throat length of 0.5. The thing of -1.0mm is used preferably.

Moreover, it is preferable that the number of punching is 1000-8000 / cm < ² >. By setting the number of punches to preferably 1000 / cm ² or more, denseness can be obtained and high-precision finishing can be obtained. On the other hand, when the number of punching is preferably 8000 / cm ² or less, deterioration of workability, fiber damage, and strength reduction can be prevented.

  Moreover, when performing a water jet punch process, it is preferable to perform water in the state of a columnar flow. Specifically, it is a preferred embodiment that water is ejected from a nozzle having a diameter of 0.05 to 1.0 mm at a pressure of 1 to 60 MPa.

The apparent density of the nonwoven fabric composed of the composite fiber after the needle punching process or the water jet punching process is preferably 0.15 to 0.45 g / cm ³ . By making the apparent density preferably 0.15 g / cm ³ or more, the artificial leather has sufficient form stability and dimensional stability. On the other hand, when the apparent density is preferably 0.45 g / cm ³ or less, a sufficient space for applying the elastic polymer can be maintained.

  From the viewpoint of densification, it is preferable that the nonwoven fabric made of ultrafine hollow fiber-generating fibers thus obtained is shrunk by dry heat or wet heat or both, and further densified.

  The method of expressing the ultrafine hollow fiber from the ultrafine hollow fiber generating fiber of the composite fiber is obtained by immersing a non-woven fabric composed of the ultrafine hollow fiber generating fiber in a solvent, and the sea component and the island component of the ultrafine hollow fiber generating fiber. This can be done by dissolving and removing the Nakaumi components.

  As the solvent for dissolving and removing the sea component and the middle sea component of the ultrafine hollow fiber generating fiber, when the sea component and the middle sea component are polyethylene, polypropylene, and polystyrene, an organic solvent such as toluene or trichloroethylene can be used. Further, when the sea component and the middle sea component are copolyester or polylactic acid, an alkaline aqueous solution such as sodium hydroxide can be used. Further, when the sea component and the Nakaumi component are water-soluble thermoplastic polyvinyl alcohol resins, hot water can be used.

  Since the Nakaumi component provided in the island component can be dissolved and removed with the same solvent as the sea component, an ultrafine hollow fiber can be produced by a single dissolution treatment.

  Further, the ultrafine fiber generation processing (sea removal treatment) can be performed by immersing and extracting a non-woven fabric made of ultrafine fiber generation type fibers in a solvent.

  In addition, for the ultrafine fiber generation processing, known apparatuses such as a continuous dyeing machine, a vibro-washer type sea removal machine, a liquid dyeing machine, a Wins dyeing machine, and a jigger dyeing machine can be used.

  The elastic polymer may be applied before the ultrafine hollow fiber generation processing, or may be applied after the ultrafine hollow fiber generation processing or after forming the hollow portion.

  As an elastic polymer, N, N′-dimethylformamide, dimethyl sulfoxide, or the like is preferably used as a solvent used for imparting polyurethane, but it is used as a water-dispersed polyurethane liquid in which polyurethane is dispersed as an emulsion in water. You can also.

  The elastic polymer is applied to the non-woven fabric by immersing the non-woven fabric in an elastic polymer solution dissolved in a solvent, and then dried to substantially solidify and solidify the elastic polymer. In the case of a solvent-based polyurethane solution, it can be solidified by immersing it in an insoluble solvent, and in the case of a water-dispersed polyurethane liquid having gelling properties, a dry coagulation method for drying after gelation, etc. Can be solidified. In drying, it is preferable to heat at a temperature that does not impair the performance of the nonwoven fabric and the elastic polymer.

  It is preferable that the sheet-like material for a water absorbing roll of the present invention is not subjected to napping treatment. By not performing the napping treatment, it is possible to obtain a structure in which the ultrafine hollow fibers and the polymer elastic body mainly composed of polyurethane that fixes the ultrafine hollow fibers are present on both surfaces of the water-absorbing roll sheet. .

  Next, the water absorption roll which can use the sheet-like material for water absorption rolls of this invention suitably is demonstrated.

  A water absorption roll is for wiping off the water, oil, etc. adhering to processed materials, such as an iron plate and a film. As a manufacturing method thereof, for example, a water-absorbing roll sheet-like material is punched into a donut shape, and punched into a metal shaft having a hollow portion inside and a plurality of holes leading to the internal cavity on the surface. The doughnut-shaped sheet for water absorption rolls is passed through and laminated in the axial direction. The laminated water absorbent roll sheet is adjusted to a desired surface hardness by compression, and then the surface is polished to prepare the water absorbent roll.

  The water-absorbing roll can be used by pressing the water-absorbing roll against the treated material with water or oil adhering, soaking water or oil into the sheet on the roll surface, and then absorbing the water inside the decompressed shaft to the outside. Discharged. The water-absorbing roll is used by rotating it while applying pressure to the processed material in accordance with the speed at which the processed material is conveyed in the process.

  As a mechanism for wiping off water, oil, etc. adhering to the processed material with the water absorption roll, the water-absorbing roll sheet on the surface of the water absorption roll is compressed by pressing the water absorption roll against the processed material, and the processed material is compressed. By adhering to the water, the adhering water and oil are blocked. Thereafter, when the water absorption roll rotates and the compression is released, the water, oil, etc. that are blocked are taken into the sheet. Then, it is discharged to the outside by decompression in the roll shaft. At that time, water and oil are taken into the water-absorbing roll sheet material by the capillary effect due to the fine gaps formed in the water-absorbing roll sheet material, but the structure of the water-absorbing roll sheet material of the present invention According to the above, in addition to the fine voids formed by the ultrafine fibers and the bundle of ultrafine fibers, the short fiber of the ultrafine hollow fibers improves the capillary effect due to the hollow cross section existing in the water-absorbing roll sheet. A water-absorbing roll having unprecedented wiping performance is obtained.

  Next, the sheet-like material for water-absorbing rolls according to the present invention and the method for producing the same will be described with specific examples.

[Measuring method and processing method for evaluation]
(1) Melting point of polymer:
The melting point of the polymer was determined by using a DSC-7 manufactured by Perkin Elmer Co., and the peak top temperature at which the polymer melted at 2nd run as the melting point of the polymer. The rate of temperature increase at this time was 16 ° C./min, and the sample amount was 10 mg. The measurement was performed twice, and the average value was taken as the melting point.

(2) Polymer melt flow rate (MFR):
MFR puts 4 to 5 g of sample pellets into a cylinder of an MFR meter electric furnace, and is extruded for 10 minutes using Toyo Seiki's melt indexer (S101) under a load of 2160 gf and a temperature of 285 ° C. The amount of resin (g) was measured. The same measurement was repeated 3 times, and the average value was defined as MFR.

(3) Average single fiber diameter of the ultrafine fibers in the water-absorbing roll sheet:
The average single fiber diameter was determined by observing the cross section of the single fiber at 3000 times with a scanning electron microscope (VE-7800 manufactured by SEM KEYENCE). Single fibers were randomly extracted within a 30 μm × 30 μm field of view, and the diameters of 50 single fibers were measured. However, this was performed at three locations, and the diameters of a total of 150 single fibers were measured and calculated as number average values. When the fiber has an irregular cross section, the cross sectional area of the single fiber was first measured, and the diameter of the single fiber was calculated by calculating the diameter when the cross section was assumed to be circular.

(4) Number of hollow portions in the ultrafine fiber:
The number of hollow portions was determined by observing a cross section of a single fiber at 3000 times using a scanning electron microscope (SEM). Single fibers were randomly extracted within a 30 μm × 30 μm visual field, the number of hollow portions was determined for 30 fibers, and the number average value thereof was calculated.

(5) Hollow ratio in ultrafine fiber:
The hollow ratio in the ultrafine fibers was determined by observing the cross section of the single fiber at 3000 times using a scanning electron microscope (SEM). Single fibers are randomly extracted within the field of view of 30 μm × 30 μm, and the total area Sa of the single fiber cross section for 30 fibers (the total area within the closed curve including the hollow portion and surrounded by the outer contour of the fiber cross section) The hollow area Sb of the single fiber cross section was measured and determined as Sb / Sa × 100 (%), which was the number average value.

(6) Compression rate:
A sample of 1 m square (1 m × 1 m) was taken from the sheet for a water absorption roll, and 10 pieces of 5 cm square (5 cm × 5 cm) sample pieces were randomly selected from the sample, and JIS L1913.6.12 (2005). The compression ratio was measured by this method, and the average value was taken as the compression ratio. The load during measurement was 60 kPa.

(7) Water absorption performance:
The water absorption performance was calculated by the following calculation formula from the weight before and after the wiping treatment was performed on the iron plate coated with water with the produced water absorption roll.
Water absorption performance (%) = (mass of applied water−mass of water after treatment) / mass of applied water
× 100
Iron plate size: 30mm x 30mm
Water application amount: 100 g / m ²
Water absorption roll diameter: 100mm
Processing speed: 100 m / min.

[Example 1]
<Raw cotton>
(Island component polymer)
Polyethylene terephthalate (PET) having a melting point of 260 ° C. and MFR of 46.5 was used.

(Sea component polymer)
Polystyrene (PSt) having a Vicat softening point of 100 ° C. and MFR of 120 measured according to JIS K7206 was used.

(Spinning and drawing)
Using the above-mentioned sea component polymer and island component polymer, using the sea-island type compound spinneret with 14 islands and 4 seas in each island, 14 islands / hole, 4 seas / island The melt spinning was performed under the conditions that the spinning temperature was 285 ° C. and the mass ratio of the island component / the Nakaumi component / the open sea component (the sea component to the island component) was 47/23/30.

  Subsequently, two-stage drawing was performed in a drawing liquid bath at a temperature of 85 ° C. so that the total magnification was 2.7 times, and crimping was performed using a stuffing box type crimper to obtain a sea-island type composite fiber. The obtained sea-island type composite fiber had a single fiber fineness of 3.8 dtex and a shrinkage rate at a temperature of 98 ° C. of 14.0%. The composite fiber thus obtained is cut to a fiber length of 51 mm, and the cross section of the fiber is a sea-island type composite fiber having a three-layer structure of (sea component) outer sea component, island component and Nakaumi component (sea component in the island component). Obtained raw cotton.

<Nonwoven fabric>
Using the raw cotton obtained as described above, a laminated fiber web was formed through a card and a cross wrapper process. Next, using a needle punch machine in which one needle having a total barb depth of 0.075 mm was implanted into the obtained laminated fiber web, a needle punch was performed at a needle depth of 7 mm and a number of punches of 2700 / cm ^2. And a nonwoven fabric having a basis weight of 770 g / m ² and an apparent density of 0.198 g / cm ³ was produced.

<Sheet>
After shrinking the nonwoven fabric with hot water at a temperature of 98 ° C., the nonwoven fabric was impregnated with an aqueous solution of PVA (polyvinyl alcohol) having a concentration of 13% and dried with hot air at a temperature of 120 ° C. for 10 minutes. A nonwoven fabric having a PVA mass of 50 mass% relative to the mass was obtained. The nonwoven fabric obtained in this way was immersed in trichlorethylene to dissolve and remove sea components, and a nonwoven fabric (sea removal sheet) made of ultrafine hollow fibers was obtained. The nonwoven fabric (sea removal sheet) made of ultrafine fibers thus obtained is immersed in a DMF (dimethylformamide) solution of polycarbonate polyurethane having a solid content adjusted to 12%, and then in an aqueous solution having a DMF concentration of 30%. To solidify the polyurethane. Thereafter, PVA and DMF are removed with hot water and dried with hot air at a temperature of 110 ° C. for 10 minutes, so that the polyurethane mass is 55% by mass with respect to the mass of the ultrafine fibers made of island components. Got.

  The ultrafine fibers in the obtained sheet for water absorbing rolls had an average single fiber diameter of 4.4 μm and a hollowness ratio of 44%. Moreover, the compressibility of the water-absorbing roll sheet was 17%, and the water absorption performance was good with no residual liquid. The results are shown in Table 1.

[Example 2]
<Raw cotton>
(Island component polymer and sea component polymer)
The same island component polymer and sea component polymer were used as in Example 1.

(Spinning and drawing)
Implementation was performed except that the sea component polymer and island component polymer were used, the mass ratio of the island component / middle sea component / outer sea component was 72/12/16, and the single fiber fineness of the sea island type composite fiber was 3.3 dtex. Raw material of sea-island type composite fiber was obtained in the same manner as in Example 1.

<Nonwoven fabric>
Using the above raw cotton, processing was carried out in the same manner as in Example 1 to produce a nonwoven fabric.

<Sheet>
Except having used said nonwoven fabric, it carried out similarly to Example 1, and obtained the sheet-like material for water absorption rolls. The ultrafine fibers in the obtained sheet for water absorption rolls had an average single fiber diameter of 4.4 μm and a hollowness of 20%. Moreover, the compressibility of the water-absorbing roll sheet was 9%, and the water absorption performance was good with no residual liquid. The results are shown in Table 1.

[Example 3]
<Raw cotton>
(Island component polymer and sea component polymer)
The same island component polymer and sea component polymer used in Example 1 were used.

(Spinning and drawing)
Using the sea component polymer and island component polymer described above, each island has 14 islands and 6 seas in each island. A sea-island composite fiber raw cotton is obtained in the same manner as in Example 1 except that the mass ratio of / sea sea component / outside sea component is 39/27/34 and the single-fiber fineness of the sea-island composite fiber is 6.1 dtex. It was.

<Nonwoven fabric>
Using the above raw cotton, processing was performed in the same manner as in Example 1 to produce a nonwoven fabric.

<Sheet>
A sheet-like material was obtained in the same manner as in Example 1 except that the above nonwoven fabric was used. The ultrafine fibers in the obtained sheet-like material had an average single fiber diameter of 5.5 μm and a hollow ratio of 50%. Further, the compression rate of the sheet-like material was 13%, and the water absorption performance was good with no residual liquid. The results are shown in Table 1.
[Example 4]
<Raw cotton>
(Island component polymer and sea component polymer)
The same island component polymer and sea component polymer used in Example 1 were used.

(Spinning and drawing)
Using the sea component polymer and island component polymer described above, each island has 14 sea island components and 14 islands, and the island component using a sea island type compound spinneret having 14 islands / hole and 48 sea islands / island. A sea-island composite fiber raw cotton is obtained in the same manner as in Example 1 except that the mass ratio of the / sea sea component / outside sea component is 39/27/34 and the single-fiber fineness of the sea-island composite fiber is 3.9 dtex. It was.

<Nonwoven fabric>
Using the above raw cotton, processing was performed in the same manner as in Example 1 to produce a nonwoven fabric.

<Sheet>
A sheet-like material was obtained in the same manner as in Example 1 except that the above nonwoven fabric was used. The ultrafine fibers in the obtained sheet-like material had an average single fiber diameter of 4.4 μm and a hollow ratio of 50%. Further, the compressibility of the sheet-like material was 11%, and the water absorption performance was good with no residual liquid. The results are shown in Table 1.

[Comparative Example 1]
<Raw cotton>
(Island component polymer and sea component polymer)
The same island component polymer and sea component polymer as in Example 1 were used.

(Spinning and drawing)
Using the sea component polymer and island component polymer described above, using a sea-island type composite spinneret with 14 islands and 14 islands / hole, and 1 / island with 1 sea / middle sea component in 14 islands. In the same manner as in Example 1, except that the mass ratio of the island component / the Nakaumi component / the open sea component was 39/27/34 and the single fiber fineness of the sea-island type composite fiber was 3.9 tex, Obtained raw cotton <nonwoven fabric>
Using the above raw cotton, processing was performed in the same manner as in Example 1 to produce a nonwoven fabric.

<Sheet>
A sheet-like material was obtained in the same manner as in Example 1 except that the above nonwoven fabric was used. The ultrafine fibers in the obtained sheet-like material had an average single fiber diameter of 4.4 μm and a hollow ratio of 50%. Moreover, the compressibility of the sheet was as high as 24%, and the water absorption performance was insufficiently wiped off. The results are shown in Table 1.

[Comparative Example 2]
<Raw cotton>
(Island component polymer and sea component polymer)
The same island component polymer and sea component polymer used in Example 1 were used.

(Spinning and drawing)
Using the sea component polymer and island component polymer described above, each island has 16 islands / hole sea-island type compound spinneret with no sea-sea component, and the island component / sea component mass ratio is 80. / 20 was obtained in the same manner as in Example 1 except that the single fiber fineness of the sea-island composite fiber was changed to 4.2 tex.

<Nonwoven fabric>
Using the above raw cotton, processing was performed in the same manner as in Example 1 to produce a nonwoven fabric.

<Sheet>
A sheet-like material was obtained in the same manner as in Example 1 except that the above nonwoven fabric was used. The average single fiber diameter of the ultrafine fibers in the obtained sheet was 4.4 μm. Moreover, the compression rate of the sheet-like material was 7%, and the water absorption performance was insufficiently wiped off. The results are shown in Table 1.
[Comparative Example 3]
<Raw cotton>
(Island component polymer and sea component polymer)
The same island component polymer and sea component polymer used in Example 1 were used.

(Spinning and drawing)
Using the above-mentioned sea component polymer and island component polymer, 10 islands have 6 sea mid-sea components in each island, 10 islands per island and 6 sea islands / island island type compound spinneret. In the same manner as in Example 1 except that the mass ratio of the component / Nakaumi component / outside sea component was 50/35/15 and the single fiber fineness of the sea-island composite fiber was 13.4 tex, Obtained <nonwoven fabric>
Using the above raw cotton, processing was carried out in the same manner as in Example 1 to produce a nonwoven fabric.

<Sheet>
A sheet-like material was obtained in the same manner as in Example 1 except that the above nonwoven fabric was used. The ultrafine fibers in the obtained sheet-like material had an average single fiber diameter of 11 μm and a hollow ratio of 50%. Moreover, the compression rate of the sheet-like material was 8%, and the water absorption performance was insufficiently wiped off. The results are shown in Table 1.

Claims (5)

  Sheet-like material in which a polymer elastic body mainly composed of polyurethane is contained in a nonwoven fabric in which short fiber bundles made of ultrafine hollow fibers having an average fiber diameter of 0.05 μm or more and 10 μm or less are entangled A polyurethane having 2 to 60 hollow portions in the fiber cross section of the ultrafine hollow fiber and fixing the ultrafine hollow fiber and the ultrafine hollow fiber to both surfaces of the sheet-like material. A sheet-like material for a water-absorbing roll, characterized in that a polymer elastic body as a component exists.   The sheet-like article for a water-absorbing roll according to claim 1, wherein the hollow ratio of the ultrafine hollow fiber is 30 to 80%.   The sheet-like article for a water-absorbing roll according to claim 1 or 2, wherein the compressibility in the thickness direction of the sheet-like article is 1% or more and 20% or less.   The ultrathin hollow fiber is made of a polyester polymer, The sheet-like material for a water absorbing roll according to any one of claims 1 to 3.   The sheet for water-absorbing rolls according to any one of claims 1 to 4, wherein the polyurethane is a polycarbonate-based polyurethane.