JP6878206B2 - Wet wiping sheet - Google Patents

Description

The present invention relates to a wet wiping sheet.

In recent years, fiber aggregates in which ultrafine fibers having a fiber diameter of about 1 μm are entangled have been used for various purposes. For example, Patent Document 1 describes a sheet-like fiber aggregate in which fibers for a base material having a fiber diameter of 15 to 50 μm and ultrafine short fibers having a fiber diameter of 0.2 to 5 μm, which are used as a sound absorbing material, are entangled with each other. It is disclosed. It is described in the same document that this fiber aggregate is not only excellent in sound absorption, but also excellent in morphological stability, processability, and handleability.

Patent Document 2 discloses a filter material for an air filter containing a sheet-like fiber aggregate formed by three-dimensionally entwining nanofibers having a diameter of 300 nm or less. It is stated that the nanofibers may be made by the electrospinning method. Further, the document describes that the dust collection efficiency can be improved by setting the relationship between the fiber diameter of the nanofibers and the basis weight of the sheet-like fiber aggregate within a predetermined range.

Japanese Unexamined Patent Publication No. 2009-287143 Japanese Unexamined Patent Publication No. 2012-183538

By the way, as an article for wiping a hard surface such as flooring or furniture, a wiping sheet made of a non-woven fabric containing ultrafine fibers is often used. Although the above-mentioned Patent Documents 1 and 2 describe techniques related to ultrafine fibers, the fiber aggregates containing the ultrafine fibers described in these documents are intended for application to sound absorbing materials or air filters, and are used for cleaning. There is no mention of the functionality of the fiber aggregates for cleaning purposes.

Therefore, an object of the present invention is to provide a wet sheet having a fiber aggregate containing large diameter fibers and ultrafine fibers and suitable for wiping.

The present invention includes a first fiber and a second fiber having a diameter smaller than that of the first fiber, includes a fiber aggregate formed by entanglement of these fibers, and has a first surface used as a wiping surface. A wet wiping sheet having a second surface located on the opposite side of the first surface.
The abundance ratio of the second fiber is higher in the first surface than in the second surface.
The basis weight of the fiber aggregate is 50 g / m ² or more and 90 g / m ² or less.
The light transmittance of the fiber aggregate in a dry state at a wavelength of 550 nm is 3% or more and 8% or less.
It provides a wet wiping sheet in which the wiping liquid is at least supported on a fiber assembly located on the second surface side.

According to the present invention, it is possible to provide a wet wiping sheet that has both the durability of wiping liquid release and the improvement of operability during use.

FIG. 1 is a scanning electron microscope image obtained by imaging a vertical cross section of the wet wiping sheet of the present invention using a scanning electron microscope. FIG. 2 is a schematic view of a manufacturing apparatus used for manufacturing the wet wiping sheet of the present invention. FIG. 3 is a graph for evaluating the liquid release property of the wet wiping sheets of Examples and Comparative Examples. FIG. 4 is a graph for evaluating the wiping resistance of the wet wiping sheets of Examples and Comparative Examples. FIG. 5 is a graph for evaluating the light transmission in the wet wiping sheets of Examples and Comparative Examples.

Hereinafter, the wet wiping sheet of the present invention (hereinafter, also simply referred to as “wiping sheet”) will be described based on its preferred embodiment. In the present invention, wiping includes both meanings of cleaning and cleaning, for example, cleaning of buildings such as floors, walls, ceilings and pillars, cleaning of fittings and fixtures, wiping of articles, body and body. Includes cleaning of equipment related to.

The wiping sheet of the present invention is composed of a fiber aggregate and is impregnated with a wiping liquid. The fibers constituting the fiber aggregate include at least a first fiber and a second fiber having a diameter smaller than that of the first fiber. The first fiber and the second fiber are entangled with each other by the first fiber, the second fiber, and the first fiber and the second fiber to form the above-mentioned fiber aggregate. The wiping sheet of the present invention may be the fiber aggregate itself impregnated with the wiping liquid, or may have other members in addition to the fiber aggregate.

The fiber aggregate used for the wiping sheet is a composite fiber aggregate mainly composed of the entanglement of the first and second fibers. Here, the wiping surface of the wiping sheet is also referred to as a front surface or a first surface, and a surface opposite to the wiping surface is also referred to as a back surface or a second surface. Further, supporting at least the wiping liquid on the fiber aggregate on the opposite side of the wiping surface means that the fiber aggregate on the opposite side of the wiping surface contains the wiping liquid, and the fiber aggregate on the wiping surface side also has a gap thereof. Also includes an embodiment containing a wiping liquid. It should be noted that preferably, the amount of the wiping liquid supported is larger than the amount of the wiping liquid supported on the fiber aggregate on the opposite side of the wiping surface.

FIG. 1 shows a vertical cross section of an embodiment of the wiping sheet of the present invention. As shown in the figure, the wiping sheet is composed of a first fiber and a second fiber having a diameter smaller than that of the first fiber. The wiping sheet also has a first surface and a second surface located on the opposite side of the first surface. The first surface of the wiping sheet is provided as a wiping surface when the wiping sheet is used. As shown in FIG. 1, a fiber aggregate of a second fiber, which is a fiber having a small fiber diameter, exists on the upper side of the figure, and this is a wiping surface (first surface). Therefore, the lower side of the figure is a surface (second surface) located on the opposite side of the wiping surface.

As shown in FIG. 1, in the vertical cross-sectional view of the wiping sheet, the locations where the first fibers and the second fibers are present are unevenly distributed. Specifically, in the wiping sheet, the presence ratio of the second fiber is a first surface (the figure) that is a wiping surface rather than a second surface (the lower side in the figure) that is a surface opposite to the wiping surface. It is higher at the upper side). Further, on the wiping surface, the second fibers are scattered in the surface direction while maintaining a high abundance ratio. By adopting this configuration, the wiping effect of the wiping sheet can be enhanced. At the same time, a large amount of the wiping liquid can be stably supported on the wiping sheet.

From the viewpoint of further enhancing the above advantages, the area ratio of the second fiber on the wiping surface to the surface of the wiping sheet including the voids is preferably 35% or more and 99% or less, and 40% or more and 98% or less. Is more preferable, and 45% or more and 97% or less is further preferable. On the other hand, the area ratio occupied by the second fiber on the surface opposite to the wiping surface is preferably 0.5% or more and 40% or less. The area occupied by the second fiber on the wiping surface is determined, for example, by measuring the area occupied by the fiber having a small fiber diameter from an image or a photograph of the wiping surface. Hereinafter, the area occupied by the fibers can be obtained in the same manner as described above. Therefore, the area ratio is a value obtained by dividing the area occupied by the fibers by the area to be measured. In the case of% display, it is 100 times the value obtained by dividing.

Here, for example, the remaining 1% of the upper limit of 99% in the area ratio of 35% or more and 99% or less is a void. This void is necessary for the wiping liquid to be discharged to the wiping surface. By adjusting the ratio of the voids, the amount of wiping liquid released to wipe off the dirt on the surface to be wiped can be suppressed to the required amount even if the wiping is strongly wiped. Further, by setting the area ratio occupied by the second fiber on the surface opposite to the wiping surface as described above, the number of voids is increased as a result, and the amount of the wiping liquid supported is increased. If the area ratio of the second fiber on the wiping surface is too small, the wiping liquid will be released in an amount more than necessary. Therefore, the area that can be wiped becomes narrow.

Regarding the thickness direction of the wiping sheet, when considering a virtual surface parallel to the wiping surface, the area ratio occupied by the second fiber in the virtual surface tends toward the thickness direction on the opposite side of the wiping surface. , Stepwise, continuously, or a combination thereof, preferably decreases. In particular, with reference to the surface opposite to the wiping surface, the portion extending from 50% to 100% of the thickness of the wiping sheet along the thickness direction of the wiping sheet is the second portion in the virtual surface parallel to the wiping surface. By setting the area ratio occupied by the fibers in the range of 50% or more and 100% or less, the amount of the wiping liquid supported can be increased. Here, the ratio of the thickness in which the area ratio occupied by the second fiber is in the range of 50% or more and 100% or less is preferably 1% or more and 90% or less, more preferably 5% or more and 70% or less, and 7 % Or more and 50% or less are more preferable. By setting the ratio of the thickness to a preferable value as described above, it is possible to release a required amount of the wiping liquid released to wipe off the dirt on the surface to be wiped.

Here, a confocal laser scanning microscope can be used to obtain information on the inside of the wiping sheet. By using a confocal laser scanning microscope, a spectrum inside the sample can be obtained. For example, by Raman imaging the sample in the depth direction, the component distribution inside the sample can be observed nondestructively.

The wiping sheet is composed of at least two layers, a liquid retention layer that supports the wiping liquid and a release layer of the wiping liquid, and the release layer includes a wiping surface. In particular, in order to support a large amount of wiping liquid, as described above, 50% or more and 100% of the thickness of the wiping sheet is taken along the thickness direction of the wiping sheet with reference to the surface opposite to the wiping surface. For the following parts, the area ratio occupied by the second fiber on the surface parallel to the wiping surface shall be in the range of 1% or more and 100% or less. This makes it possible to form a liquid-retaining layer that supports most of the wiping liquid. On the other hand, the release layer is a portion other than the liquid retention layer including the wiping surface.

The frictional force between the wiping target surface and the wiping sheet is preferably 5 N or less when wiping by applying a pressure of 55 N ^{/ m 2} to a wiping sheet having a size of 10 cm × 25 cm. It is more preferable that there is, and it is more preferable that it is 4N or less. The lower limit of the resistance is not particularly limited, and the lower the value, the more preferable. However, if the resistance is as low as about 0.8 N, the wiping operation can be smoothly performed.

The resistance force at the time of wiping can be measured in detail as follows. The head of a quick wiper (manufactured by Kao Corporation) with an alligator-shaped clip attached to the tip of a push-pull gauge (RX-20, manufactured by Aiko Engineering Co., Ltd.) and a wiping sheet with a size of 285 mm x 205 mm attached to the clip. To install. The maximum load recorded on the push-pull gauge when this head portion is scanned for 1 m at a speed of 1 cm / sec on a flooring (Combit New Advance 101, manufactured by Wood One Co., Ltd.) is measured as a resistance force.

In the wiping sheet, it is preferable that the capillary pressure on the wiping surface side is higher than that on the opposite side of the wiping surface. As a result, even when wiping with a strong force, the amount of wiping liquid released to wipe off the dirt on the surface to be wiped can be controlled to a required amount. Therefore, even in the case of wiping with a large wiping area such as a rug, carpet, or floor, it is not necessary to replace the wiping sheet with a new wiping sheet during wiping, or the number of replacements can be reduced.

Here, it is known that the capillary pressure follows the following relationship.
Pc = 2kγ _L / r × cosθ
In the formula, Pc is the capillary pressure (N / m ² ) of the _{fiber aggregate, γ L} is the surface tension of the liquid (N / m), and θ is the contact angle (rad) between the fiber and the liquid. r is the fiber diameter (m) and k is the correction coefficient.

The Pc derived by the above formula is a value using the summary statistic derived from the measurement of the fiber aggregate. In order to measure Pc, it is necessary to measure the surface tension of the liquid, the fiber diameter, the contact angle between the fiber and the liquid, and the correction coefficient. The surface tension is an automatic surface tension meter based on the plate method such as DY-200 manufactured by Kyowa Interface Science Co., Ltd. H. The average value measured 10 times in the environment of. The fiber diameter is measured by observing with a scanning electron microscope and measuring 30 fibers per observation at an observation magnification of 350 times, and this is taken as the average value of measuring 150 fiber diameters at a total of 5 locations at random. For the contact angle between the fiber and the liquid, the constituent fibers of the fiber aggregate are identified by Fourier transform infrared spectroscopy (FTIR), and the contact angle on the resin plate having the same composition is measured. Specifically, the contact angle when 3 seconds have passed after dropping 1 μL with a fully automatic contact angle meter such as DMo-901 manufactured by Kyowa Interface Science Co., Ltd. is measured at 5 points on the plate and used as the average value. .. If there are multiple fiber materials, the contact angle is measured in the same way for each material, and the value at the time of Pc calculation is the weighted average of the contact angles based on the surface area ratio of each fiber component. Let it be θ in. The correction coefficient is obtained by measuring the Krem water absorption degree specified in JIS P 8141, measuring the water absorption weight of the liquid from the water absorption height, and dividing the water absorption weight of the liquid by the total amount of the capillary sections constituting the non-woven fabric. The correction coefficient k is calculated from the Pc measured in this way, from which the capillary pressure Pc can be derived.

As is clear from the above formula, the smaller the fiber diameter, the higher the capillary pressure. In the wiping sheet of the present invention, the capillary pressure on the wiping surface side is increased by reducing the fiber diameter.

The fibers constituting the wiping sheet are at least two types of fibers having different fiber diameters. Typical fibers are polyester, polyamide, polyolefin, cellulose fibers, and fibers made from various metals, glass, and minerals. Of these, polyester, polyamide, polyolefin, and cellulose fibers are preferably used as raw materials.

The polyester is not particularly limited as long as it has a structure having an ester bond in the polymer main chain. Examples of the polyester include polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polybutylene naphthalate (PBN).

Polyolefins are obtained from monomers having ethylenically unsaturated groups. Examples of the polyolefin include polyethylene, polypropylene, ethylene-propylene copolymer, polyvinyl acetate, ethylene-vinyl acetate copolymer, cyclic acetal of polyvinyl alcohol, acrylic resin (including acrylic resin and methacrylic resin), and polyvinyl chloride. Can be mentioned. As described above, the polyolefin may be a homopolymer or a copolymer.

The polyamide may be any polyamide as long as it has a structure having an amide bond in the polymer main chain. For example, polycondensation nylon such as nylon 6, nylon 11, nylon 12 and cocondensation nylon such as nylon 66, nylon 610, nylon 612, nylon 6T, nylon 6I, nylon 9T, and nylon M5T can be mentioned. Moreover, the polyamide obtained by the following diamine component and a dicarboxylic acid component can be mentioned.

Diamine components include tetramethylenediamine, pentamethylenediamine, 2-methylpentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2,2,4-trimethyl. Examples thereof include aliphatic diamine compounds such as −hexamethylenediamine and 2,4,4-trimethylhexamethylenediamine. In addition, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, bis (4-aminocyclohexyl) methane, 2,2 Examples thereof include alicyclic diamine compounds such as -bis (4-aminocyclohexyl) propane, bis (aminomethyl) decalin, and bis (aminomethyl) tricyclodecane. Further, examples thereof include diamine compounds having an aromatic ring such as metaxylylenediamine, paraxylylenediamine, bis (4-aminophenyl) ether, paraphenylenediamine and bis (aminomethyl) naphthalene.

Examples of the carboxylic acid component include aliphatic dicarboxylic acid compounds such as succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, adipic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid. Further, phthalic acid compounds such as isophthalic acid, terephthalic acid and orthophthalic acid can be mentioned. Further, 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, Examples thereof include naphthalenedicarboxylic acid compounds such as 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid and 2,7-naphthalenedicarboxylic acid.

These diamine components and dicarboxylic acid components, including nylons, may be used alone or in combination.

The cellulose fiber may be a natural fiber or a synthetic fiber, and examples of the synthetic fiber include an acylate fiber such as cellulose acetate and rayon.

Further, these mixed fibers, for example, polyethylene / polyethylene terephthalate, polypropylene / polyethylene terephthalate and the like can also be mentioned.

In the present invention, among the above fibers, polyethylene terephthalate, polypropylene, acrylic resin, nylons and cellulose fibers are more preferable. The acrylic resin preferably has a repeating unit obtained from acrylic acid or an ester thereof, or methacrylic acid or an ester thereof.

The fiber length of the fiber, that is, the average fiber length of the entire fiber used in the present invention depends on the method for producing the fiber, but is generally preferably 1 mm or more and 100 mm or less, more preferably 10 mm or more and 90 mm or less, and further preferably 20 mm or more and 60 mm or less. ..

The diameter of the first fiber is preferably 10 μm or more and 30 μm or less, and more preferably 15 μm or more and 25 μm or less. On the other hand, the diameter of the second fiber 40 is preferably 0.1 μm or more and 9 μm or less, and more preferably 0.5 μm or more and 5 μm or less.

The first fiber and the second fiber, which are fibers having different fiber diameters, may be fibers having the same component or different components, but in the present invention, fibers having different components are preferable. .. Further, the fiber lengths may be different or the same for each other, but in the present invention, fibers having the same fiber length are preferable.

The basis weight of the fiber aggregate formed by entwining the first fiber and the second fiber constituting the wiping sheet ^{is preferably 50 g / m 2} or more, more preferably 52 g / m ² or more, and 55 g / m ² or more. More preferred. The basis weight of the fiber aggregate is preferably 90 g / ^{m 2} or less, more preferably 87 g / ^{m 2} or less, 85 g / ^{m 2} or less is more preferable. Specifically, the basis weight of the fiber aggregate formed by entwining the first fiber and the second fiber constituting the wiping sheet ^{is preferably 50 g / m 2} or more and 90 g / m ² or less, and 52 g / m ² or more. 87 g / m ² or less is more preferable, and 55 g / m ² or more and 85 g / m ² or less is further preferable.

^{The basis weight of the first fiber constituting the wiping sheet is preferably 40 g / m 2} or more, more preferably 42 g / m ² or more, and 45 g / m ² on condition that the basis weight of the fiber aggregate described above is satisfied. The above is more preferable. The basis weight of the first fiber ^{is preferably 87 g / m 2} or less, more preferably 85 g / m ² or less, and even more preferably 83 g / m ² or less. ^{Specifically, the basis weight of the first fiber constituting the wiping sheet is preferably 40 g / m 2} or more and 87 g / m ² or less, preferably 42 g / m, provided that the basis weight of the fiber aggregate described above is satisfied. ² or more and 85 g / m ² or less is more preferable, and 45 g / m ² or more and 83 g / m ² or less is further preferable.

^{The basis weight of the second fiber constituting the wiping sheet is preferably 1 g / m 2} or more, more preferably 3.5 g / m ² or more, and 4 g / m 2 or more, provided that the basis weight of the fiber aggregate described above is satisfied. More than m ^{2 is} more preferable. The basis weight of the second fiber is preferably from 22.5 g / ^{m 2} or less, more preferably 10 g / ^{m 2} or less, more preferably 8 g / ^{m 2} or less. Specifically, a second basis weight of the fibers constituting the wiping sheet, the condition that satisfies a basis weight of the fiber aggregate described above, 1 g / m ² or more 22.5 g / m ² or less, and 3 .5m more preferably ² or more 10 g / ^{m 2} or less, 4g / ^{m 2} or more 8 g / ^{m 2} or less is more preferable. As described above, the basis weights of the first fiber and the second fiber are in these ranges, so that the first fiber and the second fiber are more three-dimensional when the fiber aggregate is produced. Can be entangled with. As a result, it is possible to achieve both the sustainability of the release of the wiping liquid in the wiping sheet and the improvement of operability during use.

The fiber aggregate constituting the wiping sheet preferably has a light transmittance of 3% or more, more preferably 3.5% or more, and more preferably 4% or more at a wavelength of 550 nm in a dry state. Further, the light transmittance at a wavelength of 550 nm is preferably 8% or less, more preferably 7.5% or less, still more preferably 7% or less. Specifically, the light transmittance of the fiber aggregate in the dry state at a wavelength of 550 nm is preferably 3% or more and 8% or less, more preferably 3.5% or more and 7.5% or less, 4 It is more preferably% or more and 7% or less. By satisfying this light transmittance, it is possible to achieve both the sustainability of the wiping liquid from being released from the wiping sheet and the improvement of operability during use. The "dry state" means that the amount of water contained in the fiber aggregate is 3% by mass or less.

The light transmittance refers to a percentage of the intensity ratio of transmitted light to incident light in a fiber aggregate having a specific thickness, and in the present invention, the light transmittance at a wavelength of 550 nm is measured. The method for measuring the light transmittance at a wavelength of 550 nm is not particularly limited as long as it is measured using a device capable of generating a wavelength component of at least 550 nm, and for example, a visible spectrophotometer, a fluorescent lamp, LED lighting, or the like is used as a light source. It can be measured by the device or the like. When the wiping sheet consists of the fiber aggregate itself, the fiber aggregate is measured. When the wiping sheet has other members in addition to the fiber aggregate, the fiber aggregate after removing the other members is the measurement target. The method for measuring the light transmittance will be described in detail in Examples described later.

By measuring the light transmittance at a wavelength of 550 nm, the basis weight of the second fiber (small diameter fiber) in the fiber aggregate can be indirectly estimated. Specifically, when the basis weight of the first fiber contained in the fiber aggregate constituting the wiping sheet is constant and the basis weight of the second fiber contained in the fiber aggregate is large, the basis weight is large. Since the second fibers are entangled so as to fill the voids of the fiber aggregates, the fiber aggregates become dense and the voids are reduced. As a result, the light transmittance of the fiber aggregate decreases. On the other hand, when the basis weight of the second fiber contained in the fiber aggregate is small, the voids of the fiber aggregate are maintained, so that the light transmittance increases. In such measurement of light transmittance, the first fiber and the second fiber are entangled with each other, and it is difficult to measure the basis weight of the second fiber. It is a simple and effective means for estimating the amount.

In relation to the fiber aggregate constituting the wiping sheet, the thickness of the wiping sheet is preferably 1 mm or more under a load of 40 Pa, and more preferably 1.2 mm or more in a state of being impregnated with the wiping liquid. It is preferably 1.5 mm or more, and more preferably 1.5 mm or more. Further, under the same load, it is preferably 5 mm or less, more preferably 4 mm or less, and even more preferably 3 mm or less. The thickness of the wiping sheet is preferably 0.8 mm or more and 3 mm or less under a load of 370 Pa, more preferably 0.9 mm or more and 2.8 mm or less, and further preferably 1 mm or more and 2.5 mm or less. By setting the thickness of the wiping sheet within this range, the wiping sheet has sufficient rigidity and strength, and the operability at the time of wiping is improved. In order to achieve such a thickness, the surface may be embossed, or the surface may be scraped and fluffed.

The mass ratio of the second fiber to the mass of the fiber aggregate constituting the wiping sheet is preferably 2% by mass or more, more preferably 4% by mass or more, still more preferably 6% by mass or more. The mass ratio of the second fiber is preferably 25% by mass or less, more preferably 22% by mass or less, and further preferably 20% by mass or less. Specifically, the mass ratio of the second fiber to the mass of the fiber aggregate constituting the wiping sheet is preferably 2% by mass or more and 25% by mass or less, more preferably 4% by mass or more and 22% by mass or less, and 6% by mass. % Or more and 20% by mass or less are more preferable. By having such a mass ratio, the wiping liquid can be continuously discharged and the operability of the wiping sheet can be improved.

In the present invention, it is preferable that at least the first fibers are entangled without being fused. By having such a configuration, the voids between the fibers increase and the amount of the wiping liquid supported increases as compared with the case where the fibers are fused. The first and second fibers and the second fibers may or may not be fused, but from the viewpoint of increasing the amount of the wiping liquid supported, the first and second fibers and the second fiber are used. It is preferable that they are entangled without being fused.

In the wet wiping sheet of the present invention, the amount of wiping liquid released from the wiping surface to the wiping target surface by wiping once, that is, wiping the wiping target surface once is tatami mat (1820 mm × 910 mm, area 1. When 6552 m ² ) is used as the surface to be wiped, 0.5 g / tatami or more is preferable, 0.7 g / tatami or more is more preferable, and 1.0 g / tatami or more is further preferable. The upper limit of the amount released is realistically 8 g / tatami or less, preferably 7 g / tatami or less, and more preferably 6 g / tatami or less. If the amount released is too small, it cannot be wiped sufficiently, and if it is too large, the wiping liquid tends to remain on the wiping surface. It is preferable that the amount of such wiping liquid released is maintained even after wiping with the wiping sheet of the present invention for at least 6 tatami mats.

The measurement conditions for the amount of liquid discharged are a wiping load (load W) of 0.16 kN / m ² and a wiping speed (speed V) of 1 m / s. In the wiping sheet of the present invention, the amount released per tatami mat when measured under such measurement conditions is within the above range.

The maximum amount of liquid supported by the wiping liquid on the wiping sheet, that is, the initial amount of liquid supported is 1 g / sheet or more when the dimensions of the wiping sheet are set to 285 mm × 205 mm, for example, as described in Examples described later. Preferably, 10 g / sheet or more is more preferable, and 12 g / sheet or more is further preferable. The initial upper limit of the amount of liquid supported is realistically 40 g / sheet or less, preferably 30 g / sheet or less, and even more preferably 20 g / sheet or less.

By doing so, it is possible to release a liquid amount of 1 g / tatami or more per target wiping, and it is possible to maintain the liquid release amount even after the 6th tatami mat.

The wiping liquid used for the wiping sheet is generally the same as that used for the wet wiping sheet. That is, the wiping liquid may be water alone or an aqueous solution containing a surfactant, but from the viewpoint of dirt removal efficiency, an aqueous solution containing a surfactant is preferable.

The surfactant may be any of a nonionic surfactant, an amphoteric surfactant, a cationic surfactant or an anionic surfactant. For example, an anionic surfactant such as alkylbenzene sulfonic acid or a nonionic surfactant such as polyoxyethylene alkyl ether can be used.

The wiping solution may contain additives. Examples of the additive include a polymer of acrylic acid, methacrylic acid or maleic acid or a salt thereof, and a copolymer of maleic acid and another vinyl-based monomer or a salt thereof for the purpose of enhancing the rinsing effect. Can be mentioned. Examples thereof include bactericides, fragrances, air fresheners, deodorants, abrasive particles, pH adjusters, and water-soluble organic solvents such as alcohol.

The content of surfactants and additives as described above is generally in the range used in wet wiping sheets. For example, the content of the surfactant can be 0.01% by mass to 1% by mass.

Next, a suitable manufacturing method of the wiping sheet shown in FIG. 1 will be described with reference to FIG. FIG. 2 shows a manufacturing apparatus 1 preferably used for manufacturing a wiping sheet. The manufacturing apparatus 1 includes a web forming portion 2, a first entangled portion 3, an electrostatic spinning portion 4, and a second entangled portion 5.

The web forming portion 2 forms the web of the first fiber 20. The web forming unit 2 includes a card machine 21 that forms a web from the first fiber 20 that is a raw material of the wiping sheet.

The first entanglement portion 3 entangles the web of the first fiber 20 with a water stream. The first entangled portion 3 includes a first water flow nozzle 31 that blows a water flow onto the web of the first fiber 20, and a first support belt 32 made of an endless belt. The first water flow nozzle 31 is located above the web of the first fiber 20 and the first support belt 32, and can blow a high-pressure water flow over the entire width direction of the web of the first fiber 20. ing. The first support belt 32 is arranged so as to face the first water flow nozzle 31, and has a structure in which holes are formed in a pattern such as a grid pattern in order to allow the sprayed water to pass through (not shown). ). The entangled body of the first fibers 20 entangled by the spraying of the water flow from the first water flow nozzle 31 is conveyed to the electrostatic spinning section 4 by the first support belt 32.

The electrostatic spinning section 4 generates a second fiber 40 made of nanofibers by an electrostatic spinning method, and one surface of an entanglement body of the first fiber 20 entangled by a first water flow nozzle 31 of the first entanglement section 3. It is intended to be deposited in. The electrostatic spinning unit 4 includes an injection unit 41 that injects the raw material liquid of the second fiber 40 and electrostatically spins the raw material liquid, and a collecting electrode 42 that collects the injected raw material liquid as the second fiber 40. ing. The injection unit 41 is composed of a supply unit for the raw material liquid of the second fiber 40, an electrode, a voltage application unit, and the like (not shown). A positive voltage or a negative voltage is applied to the injection unit 41. The collection electrode 42 is arranged so as to face the injection unit 41. The collection electrode 42 is made of a conductive member and is grounded.

When a voltage is applied to the injection unit 41, the raw material liquid of the second fiber 40 is charged by electrostatic induction until it is injected from the injection unit 41, and is injected in a charged state. The raw material liquid injected in the charged state causes self-repulsion of the raw material liquid due to the action of the electric field, and the second fiber 40 is generated as fine fibers (nanofibers) at the nano size level. The generated second fiber 40 is randomly deposited on one surface of the entanglement of the first fiber 20 running in the vicinity of the collection electrode 42 to form a fiber aggregate. By this electrostatic spinning step, a laminated body 50 of a fiber aggregate composed of a first fiber 20 and a second fiber 40 is formed. The obtained laminated body 50 is conveyed to the second entangled portion 5.

As the raw material liquid of the second fiber 40 in the electrostatic spinning method, a liquid in which the polymer compound constituting the second fiber 40 is dissolved or dispersed in a solvent, or a melt in which the polymer compound is melted can be used. .. A method using a liquid in which a polymer compound is dissolved or dispersed in a solvent can also be referred to as a solution-type electrostatic spinning method, and a method using a melt obtained by melting a polymer compound can also be referred to as a melt-type electrostatic spinning method. .. In the present invention, any electrostatic spinning method can be used.

In the second entanglement portion 5, a water stream is sprayed on the fiber aggregate of the first fiber 20 and the laminate 50 of the fiber aggregate of the second fiber 40 to entangle the first fiber and the second fiber. , Form a fiber assembly of the wiping sheet. The second entangled portion 5 includes a second water flow nozzle 51 that blows a water flow onto the laminated body 50 from the side of the first fiber 20, a second support belt 52 provided below the laminated body that is being conveyed, and a laminated body. It is composed of a transport belt 53 that transports 50 to a downstream manufacturing process.

As shown in FIG. 2, the second water flow nozzle 51 is located on the side of the first fiber 20 of the laminated body 50, and can blow the water flow over the entire width direction of the laminated body 50. The water flow sprayed from the second water flow nozzle 51 toward the surface on the first fiber 20 side presses the surface of the laminate 50 on the second fiber 40 side so as to be in close contact with the upper surface of the second support belt 52. .. At this time, entanglement of the first fiber 20 and the second fiber 40 occurs. Through these steps, a laminate 50 in which the first fiber 20 and the second fiber 40 are three-dimensionally entangled can be obtained.

Finally, the laminated body 50 formed by the second entangled portion 5 is conveyed downstream from the second entangled portion 5 by the conveying belt 53, and then the surface side corresponding to the second surface of the target wiping sheet. Then, the wiping liquid is supplied and supported on the fiber aggregate located on the second surface side. Through this step, the desired wiping sheet is obtained.

The amount of the wiping liquid supported is preferably 6 g / sheet or more, more preferably 8 g / sheet or more, and even more preferably 10 g / sheet or more. The upper limit of the content of the wiping liquid is preferably 40 g / sheet or less, more preferably 30 g / sheet or less, and further preferably 20 g / sheet or less. As a method of supporting the wiping liquid, a method such as spraying, coating, or dipping can be adopted.

The wiping sheet manufactured in this way can be attached to a cleaning tool such as a wiper or a building such as a floor or a wall surface, a cupboard, a window glass, a mirror, a door, a doorknob, or the like. It can also be used for rugs, carpets, furniture such as desks and dining tables, kitchens, toilets, body cleaning, hygiene products, and packaging.

Although the present invention has been described above based on the preferred embodiment, the present invention is not limited to the above embodiment. For example, in FIG. 2, the number and water pressure of the first and second water flow nozzles 31, 51 may be the same or different.

Further, after the entanglement at the second entanglement portion 5, a water stream may be further sprayed from the surface side of the second fiber 40 of the laminate 50 to entangle.

Further, the wiping sheet of the above embodiment may have a convex portion formed on the wiping surface side thereof. When forming a convex portion, the second entangled portion 5 is provided with a convex portion forming member having a plurality of open holes such as a punching metal or a plastic net between the laminated body 50 and the second support belt 52. , Can be formed by entanglement with a stream of water.

Further, although the wiping sheet of the above embodiment contains two types of fibers of the first and second fibers, a wiping sheet containing three or more types of fibers may be used instead.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the scope of the present invention is not limited to such examples.

〔Example〕
A wet wiping sheet was manufactured according to the manufacturing method described above. As the first fiber, a mixed cotton body having an average diameter of 11.4 μm containing PET: acrylic: rayon = 7: 1.5: 1.5 in a mass ratio was used. As the second fiber, polypropylene having an average diameter of 1 μm obtained by an electrospinning method was used. The basis weight of the fiber aggregate was 65 g / m ² , the basis weight of the first fiber was 60 g / m ^2, and the basis weight of the second fiber was 5 g / m ² . The area ratio of the second fiber on the wiping surface was 49%. The ratio of the second fiber in the thickness direction of the wiping sheet was 12%. The wiping sheet had a rectangular shape, its dimensions were 285 mm × 205 mm, and the thickness after impregnation with the wiping liquid was 1.08 mm. The wiping liquid was at least supported on the fiber assembly located on the second surface side. The amount of the wiping liquid supported was 20 g / sheet. As the wiping liquid, a 0.01 mass% aqueous solution of a surfactant (Emargen (registered trademark) 108, manufactured by Kao Corporation) was used.

[Comparative example]
As the wet wiping sheet, a wet sheet for floors of Scotch-Brite (registered trademark) manufactured by 3M Co., Ltd. was used. This wet wiping sheet is made of a fiber aggregate of small diameter fibers and large diameter fibers. The thickness was 1.3 mm.

[Evaluation of liquid release property]
^{A load of 0.16 kN / m 2} is applied to the wet wiping sheets of Examples and Comparative Examples, and the wiping speed is 1 m / s. The liquid release amount (g) was measured for each tatami mat. The results are shown in FIG.

[Evaluation of wiping resistance]
^{A pressure of 55 N / m 2} was applied to the wet wiping sheets of Examples and Comparative Examples to wipe an area ^{of 1.8 m 2} with a flooring (Combit New Advance 101, manufactured by Wood One Co., Ltd.) as a wiping target surface. The resistance force (N) at that time was measured by the above-mentioned method. The results are shown in FIG.

[Evaluation of light transmittance]
After the wet wiping sheets of Examples and Comparative Examples are dried, the light transmittance at a wavelength of 300 to 800 nm is measured at a wavelength of 300 nm to 800 nm using a light transmittance measuring device (Hitachi High-Tech Science Co., Ltd., U-3310). The transmittance in the region was measured in 1 nm increments and plotted. The results are shown in FIG.

When the liquid release property of the wet wiping sheets of Examples and Comparative Examples was evaluated, as shown in FIG. 3, in Examples, the amount of liquid released at the first tatami mat was suppressed as compared with Comparative Examples. The amount of liquid released after the 5th tatami mat is maintained at 1 g / tatami mat. From this, it can be seen that in the wet wiping sheet of the example, the amount of liquid released is substantially uniform.

Moreover, when the wiping resistance in the wet wiping sheet of the example and the comparative example was evaluated, it was 4N in the example and 12N in the comparative example as shown in FIG. From this, it can be seen that in the wet wiping sheet of the example, the frictional resistance force at the time of wiping is small and the operability is improved.

Further, when the light transmittances of the wet wiping sheets of Examples and Comparative Examples were evaluated, as shown in FIG. 5, the light transmittance at a wavelength of 550 nm was 7% in Examples, whereas the light transmittance of Comparative Examples was 7%. Then it was 9.8%. From this, it can be seen that in the wet wiping sheet of the example, the light transmittance is low and the first and second fibers are more three-dimensionally entangled.

Claims (4)

A first surface which contains at least a first fiber and a second fiber having a diameter smaller than that of the first fiber, includes a fiber aggregate formed by entwining these fibers, and is used as a wiping surface, and the first surface thereof. A wet wiping sheet having a second surface located on the opposite side of the surface.
The abundance ratio of the second fiber is higher in the first surface than in the second surface.
The basis weight of the fiber aggregate is 50 g / m ² or more and 90 g / m ² or less.
The light transmittance of the fiber aggregate in a dry state at a wavelength of 550 nm is 3% or more and 8% or less.
A wet wiping sheet in which the wiping liquid is at least supported on a fiber assembly located on the second surface side. The mass ratio of the second fiber to the mass of the fiber aggregate is 2% by mass or more and 25% by mass or less.
The wet wiping sheet according to claim 1, wherein at least the first fibers are not fused to each other. The wet wiping sheet according to claim 1 or 2, wherein the basis weight of the first fiber is 40 g / m ² or more and 87 g / m ^{2 or less.} The basis weight of the second fiber is 1 g / ^{m 2} or more 22.5 g / ^{m 2} or less, the wet wiping sheet according to any one of claims 1 to 3.

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