JP5237623B2 - Sheet base material for wet sheets - Google Patents

Description

  The present invention relates to a sheet base material used for a wet sheet impregnated with a liquid.

  When a plurality of wet sheets made by impregnating a sheet base material with liquid are stacked and stored in a container, the liquid tends to move downward due to the influence of gravity, and the liquid content varies from sheet to sheet. There is a case. As a result, the performance of the liquid may not be sufficiently exhibited when the wet sheet is used. Moreover, the feeling of use is likely to decrease due to the low content of liquid. Further, in some cases, the liquid accumulates at the bottom of the container, and the liquid is wasted. For example, when the wet sheet is a makeup removing sheet, the upper sheet of the stacked sheets is inferior in cleaning properties, and the lower sheet is sticky and feels bad.

It has been proposed to use a polyolefin resin meltblown nonwoven fabric having a basis weight of 15 to 200 g / m ² in order to prevent liquid movement even when a plurality of wet sheets are stored. 1). This meltblown nonwoven fabric is characterized in that at least 65% of the pores are occupied by pores having a size of 20-60 μm. However, since the polyolefin resin is hydrophobic, when the melt-blown nonwoven fabric made from the polyolefin resin is impregnated with an aqueous liquid, it is necessary to hydrophilize the nonwoven fabric, which takes time and labor. Moreover, although it depends on production conditions, the melt-blown nonwoven fabric generally does not have a good texture. In particular, when this is used for wiping the skin, the wiping comfort may not be good.

  Therefore, the present applicant has previously proposed a sheet base material for wet sheets comprising a spunlace nonwoven fabric containing hydrophilic fibers having a fiber diameter of 0.2 to 5.5 dtex and having a fiber-to-fiber distance of 10 to 35 μm ( Patent Document 2). According to this sheet base material, there is an advantage that even if the sheet is impregnated with a liquid and stored in a laminated state, the movement of the liquid is reduced.

JP 63-54137 A JP 2005-330608 A

  An object of the present invention is to provide a sheet base material for a wet sheet whose performance is further improved as compared with the above-described conventional sheet base material.

The present invention is a wet sheet base material that is impregnated with a liquid to form a wet sheet,
The sheet base material comprises a fiber sheet containing 55% by weight or more of one or more hydrophilic fibers,
The fiber sheet has a large number of concave portions in which fibers are consolidated and convex portions having a lower degree of fiber consolidation than the concave portions, and the area ratio of the concave portions defined below is 30 to 80%. Yes,
The hydrophilic fibers provide a wet sheet base material having a fiber diameter of 0.1 to 5.5 dtex.
The area ratio of the recess means the ratio of the total area of the recess to the area of the fiber sheet when the fiber sheet is viewed in plan.

  The present invention also provides a wet sheet obtained by impregnating the wet sheet base material with a liquid.

Furthermore, the present invention is a suitable method for producing the wet sheet base material,
A card web fed from a card machine is hydroentangled to form a fiber sheet, the fiber sheet is arranged on a pattern imparting member having an opening, and a high-pressure water stream is jetted toward the fiber sheet,
The fiber sheet positioned at the opening portion in the pattern application member receives the water pressure of a high-pressure water flow while being pressed against the pattern application member, thereby forming the convex portion on the fiber sheet.
A method for producing a wet sheet base material is provided.

  According to the sheet substrate of the present invention, the feel is good, and even if a plurality of sheets are stored in a laminated state by impregnating the liquid, the movement of the liquid is reduced. Therefore, the performance of the impregnated liquid can be fully exhibited. Further, since the liquid is discharged from the sheet in an appropriate amount, the cleaning property is improved.

  The present invention will be described below based on preferred embodiments with reference to the drawings. The sheet base material of the present invention is a wet sheet that is impregnated with a liquid, and is in a dry state before the liquid is impregnated. A sheet base material consists of a fiber sheet containing a fiber material. As the fiber sheet, various woven fabrics, non-woven fabrics, knitted fabrics, composites thereof and the like can be used. In consideration of liquid retention performance and production costs, it is preferable to use various nonwoven fabrics.

  When using a nonwoven fabric as a fiber sheet, various nonwoven fabrics, such as a dry-type spunlace nonwoven fabric, a wet spunlace nonwoven fabric, an airlaid nonwoven fabric, an air through nonwoven fabric, a melt blown nonwoven fabric, a spun bond nonwoven fabric, can be used, for example. Among these nonwoven fabrics, it is preferable to use a dry spunlace nonwoven fabric or a wet spunlace nonwoven fabric from the viewpoint of liquid impregnation performance, retention performance, texture, and the like.

  The sheet base material may be composed of a single-layer fiber sheet, or may have a multilayer structure in which a plurality of fiber sheets of the same or different types are laminated and integrated. From the viewpoint of suppressing liquid movement in the wet sheet, the sheet base material is preferably composed of a single-layer fiber sheet, particularly a single-layer nonwoven fabric.

  FIG. 1 shows an embodiment of the sheet substrate of the present invention. The fiber sheet constituting the sheet substrate 10 has a large number of circular convex portions 11 and concave portions 12 surrounding the convex portions 11. Each convex part 11 is uniformly distributed in a scattered manner over the entire area of the sheet base material 10 and is independent of each other. The convex portions 11 are arranged in a row at a predetermined interval in one direction of the sheet base material 10, the rows are arranged in multiple rows, and the arrangement positions of the convex portions 11 are shifted by a half pitch in each row. ing. The concave portions 12 surrounding the convex portions 11 are connected to each other to form a continuous body over the entire area of the sheet base material 10.

  In the concave portion 12, the constituent fibers of the sheet base material 10 are consolidated and the apparent density is increased. On the other hand, in the convex part 11, the degree of consolidation of the fibers is lower than that of the concave part 12, and the apparent density is lower than that of the concave part 12.

  The degree of consolidation of the convex portion 11 and the concave portion 12 can be quantified by the inter-fiber distance of the fibers at these portions. In the convex part 11, since the degree of consolidation of the fibers is lower than that of the concave part 12, as described above, when the sheet substrate 10 is composed of a single fiber sheet, the convex part 11 is convex. The interfiber distance in the portion 11 is larger than the interfiber distance in the recess 12. Specifically, the interfiber distance in the convex portion 11 is preferably 20 to 50 μm, more preferably 25 to 40 μm. On the other hand, the inter-fiber distance in the recess 12 is preferably 10 to 50 μm, more preferably 15 to 40 μm, and still more preferably 25 to 35 μm. The interfiber distance is calculated from the following equation.

  Thus, in the sheet base material 10 of the present embodiment, the interfiber distance of the concave portion 12 is smaller than the interfiber distance of the convex portion 11. Therefore, when the sheet base material 10 is impregnated with a liquid to form a wet sheet, and the wet sheet is used, for example, for makeup removal, good liquid retention performance and dirt storage property due to the recess 12 having a small interfiber distance. Moreover, there is an advantage that makeup removal can be effectively performed by the good scraping property due to the convex portion 11 having a large interfiber distance.

  Although the reason why the sheet base material of the present invention can suppress the movement of liquid is not sufficiently clarified, the distance between fibers becomes small, which becomes resistance (resistance force) of movement of liquid, and capillary force is also reduced. The present inventors speculate that this may be due to the fact that it acts and the movement of the liquid due to gravity is suppressed. By having the recessed part 12 consolidated so that it may have the above interfiber distance, according to the sheet | seat base material 10 of this embodiment, the following advantageous effects (I) thru | or (C) are show | played. .

  (A) In the concave portion 12 in which the fibers are consolidated and the distance between the fibers is small, the resistance force and the capillary force act strongly. Therefore, when the sheet base material 10 is impregnated with various liquids, the liquids are stably held in the concave portions 12 that are portions where the resistance force and the capillary force act strongly. On the other hand, since the convex portion 11 has a larger interfiber distance than the concave portion 12, the action of the capillary force is smaller than that of the concave portion 12. Therefore, when the sheet base material 10 is viewed as a whole, a gradient is formed in which the capillary force increases from the convex portion 11 toward the concave portion 12. As a result, the liquid absorbed in the convex portion 11 is drawn into the concave portion 12 which is a portion having a higher capillary force, and is stably held in the concave portion 12. For these reasons, liquid movement is less likely to occur during wet sheet lamination. From this point of view, the concave portion 12 which is a part holding the liquid is formed so that the area ratio thereof is 30 to 80%, preferably 40 to 65%, while the convex portion 11 has an area ratio of It is formed to be 20 to 70%, preferably 35 to 60%. Here, the area ratio of the recess means the ratio of the total area of the recess to the area of the fiber sheet when the fiber sheet is viewed in plan. That is, since “the fiber sheet is seen in plan view”, the (total) area of the recesses here means a projected area. On the other hand, the area ratio of a convex part means the ratio of the total area of the convex part which occupies for the area of this fiber sheet when a fiber sheet is planarly viewed. Therefore, the sum of the area ratio of the concave portions and the area ratio of the convex portions is 100%.

  The area ratio of the recesses is measured by the following method. Cut the fiber sheet into 10 cm × 10 cm. Color the recess with black magic. This is captured as an image with a scanner under no load, and image analysis is performed with image pro, which is image analysis software, to determine the area ratio of the recesses. When the fiber sheet and the concave portion 12 are clear, it is not necessary to color with a magic.

In addition, in this embodiment, although the recessed part 12 is a continuous body, it may replace with this and may form an independent recessed part separately. Individual area of the recess of the case, 3~35mm ^2, it is particularly preferably 5 to 30 mm ^2. The individual areas of the recesses are measured by the following method. Cut the fiber sheet into 100 mm x 150 mm. The area of the recess of N = 10 is measured and averaged with a digital microscope (Keyence Corporation VHX-500). The shape of the individually independent recesses may be arbitrary, and may be, for example, a circle, a square, a rectangle, a rhombus, a herringbone, or a line.

  (B) In addition, the sheet base material 10 has projections 11 and recesses 12, and has irregularities on each surface. That is, the surface is not flat. As a result, in the state where the wet sheets are stacked and stored, the contact area between adjacent sheets in the upper and lower directions can be kept low. This makes it difficult for the liquid to move between adjacent sheets in the upper and lower directions, and makes it possible to take out the stacked sheets and to take out the sheets one by one.

  (C) In addition, since the convex portion 11 and the concave portion 12 are formed on the sheet base material 10, the concave portion 12, which is a portion having a small thickness, is likely to be a starting point of bending, so that the texture is It is flexible. This is advantageous in that when the skin is wiped using a wet sheet obtained by impregnating the sheet base material 10 of the present embodiment with a liquid, the wet sheet has good followability to the skin. . From this viewpoint, the fiber sheet preferably has a bulk softness of 0.1 to 1.0 N, particularly 0.2 to 0.5 N. When the value of bulk softness differs between the flow direction (MD) and the width direction (CD) of the sheet base material 10, the larger value is used as the bulk softness value of the sheet base material 10. Bulk softness is measured by the following method.

[Measurement method of bulk softness]
The bulk softness measurement method in the flow direction is as follows. The sheet base material is cut into a size of 30 mm in the flow direction and 150 mm in the width direction to obtain a rectangular test piece. A cylinder with a diameter of 45 mm having a height in the short side direction (30 mm direction) is made from this test piece. The overlapping width of the cylinder in the circumferential direction is about 10 mm. The upper end and the lower end of the overlapped portion are fixed with a MAX stapler HD-10D and needle No. 10-1M. The maximum load when the cylindrical measurement sample thus obtained is compressed in the height direction of the cylinder is measured by a compression tester, and the value is set as the bulk softness value. RTA-100 type (trade name) manufactured by Orientech Co., Ltd. was used as the compression tester. The compression speed is 10 mm / min. On the other hand, the bulk softness in the width direction is measured by the same method as described above by cutting the sheet base material into a size of 30 mm in the width direction and 150 mm in the flow direction, collecting a rectangular test piece.

  There is no restriction | limiting in particular in the shape of the convex part 11, For example, circular, square, a rectangle, a rhombus, a cedar, a curve, a linear form, etc. may be sufficient. The arrangement pattern of the convex portions 11 is not particularly limited. The pitch of the convex portions 11 along the flow direction of the sheet substrate 10 is preferably 1 to 10 mm, particularly preferably 1.5 to 9 mm. The pitch of the convex portions 11 along the width direction of the sheet substrate 10 is preferably 1 to 10 mm, particularly preferably 1.5 to 9 mm. These pitches are obtained by averaging the pitch values measured in the flow direction and the width direction, respectively, with the number of measurement points N = 10.

  Even after the sheet base material 10 is impregnated with a liquid to form a wet sheet, the shape and thickness of the convex portions 11 and the concave portions 12 before impregnation and the apparent density of the sheet base material 10 do not change greatly. Therefore, the contact area ratio with respect to the plane of the sheet base material 10 before being impregnated with the liquid (the ratio of the area of the sheet base material in contact with the plane relative to the area of the sheet base material) and the liquid impregnation The contact area ratio with respect to the plane of the sheet base material 10 in the state is almost the same. Here, since the site | part which contacts a plane among the sheet | seat base materials 10 is the convex part 11, the said contact area ratio becomes equal to the area ratio of the convex part mentioned above. Since it is preferable that the area ratio of a convex part is 20 to 70% as mentioned above, in other words, the contact area ratio with respect to the plane of the base material sheet 10 in the state impregnated with the liquid will be 20 to 70%. Thus, it means that the convex portion 11 is preferably formed on the fiber sheet. The contact area ratio in the wet sheet is measured under no load using the above-described image analysis software.

  In order to form the convex part 11 and the concave part 12 whose degree of consolidation is as described above, for example, the sheet base material 10 may be formed according to a method described later. Further, from the viewpoint of the fibers to be used, the sheet substrate 10 includes 55% by weight or more of hydrophilic fibers, preferably 65% or more, and more preferably 75% or more. Of course, the sheet base material 10 may be composed of 100% hydrophilic fibers. As a result, the liquid retainability is improved, and the movement of the liquid can be suppressed.

  As the hydrophilic fiber, both a fiber that is inherently hydrophilic and a fiber that is not inherently hydrophilic but made hydrophilic by a hydrophilization treatment can be used. Examples of inherently hydrophilic fibers include natural fibers such as cotton, and pulp, rayon, acrylic, cupra, lyocell, and tencel. Examples of fibers that are not originally hydrophilic but have been made hydrophilic by a hydrophilic treatment include, for example, fibers obtained by subjecting fibers made of a hydrophobic resin such as a polyolefin resin and a polyester resin to a hydrophilic treatment. Of these fibers, cotton, rayon, cupra, lyocell, and tencel are preferably used from the viewpoint of good texture, and cotton is particularly preferably used. The hydrophilic fibers can be used alone or in combination of two or more.

  The hydrophilic fiber used in the present invention has a thickness of 0.1 to 5.5 dtex, preferably 0.8 to 4.4 dtex, more preferably 1.3 to 3.3 dtex. When cotton, which is a natural fiber, is used, the cross-sectional shape is not a perfect circle. Therefore, when the aspect ratio of the cross-section is calculated as 3, it is preferable to fall within the above thickness range. When fibers having a fiber diameter in this range are used, it is easy to appropriately control the inter-fiber distance described above. When using 2 or more types of hydrophilic fiber, it is required that the thickness of at least 1 type of hydrophilic fiber exists in the said range. Preferably, the thickness of all hydrophilic fibers is within the above range.

  When cotton is used as the hydrophilic fiber, the micronea fineness (μg / in) is preferably 2.5 to 6.0 μg / in, and more preferably 3.1 to 4.4 μg / in because the feel is good.

  Although there is no restriction | limiting in particular about the fiber length of a hydrophilic fiber, 5-100 mm is preferable from the point of the touch in use and productivity.

In the fiber sheet which comprises the sheet | seat base material 10, it is preferable that the thickness of the convex part 11 is 0.3-0.7 mm, especially 0.4-0.6 mm. The thickness of the concave portion 12 is smaller than the thickness of the convex portion 11, and is preferably 0.2 to 0.5 mm, particularly preferably 0.25 to 0.4 mm. Further, the fiber sheet preferably has a basis weight of 20 to 150 g / m ² , particularly 50 to 100 g / m ² . The apparent density of the convex portions 11 is preferably 0.05 to 0.20 g / cm ³ , particularly preferably 0.10 to 0.15 g / cm ³ . The apparent density of the concave portions 12 is larger than the apparent density of the convex portions 11, and is preferably 0.10 to 0.30 g / cm ³ , particularly preferably 0.12 to 0.25 g / cm ³ . If the apparent density is within this range, the liquid holding performance can be sufficiently enhanced, and the movement of the liquid during the wet storage of the wet sheets can be suppressed. The basis weight is obtained by cutting a fiber sheet into a size of 100 mm × 100 mm, measuring its weight, and converting it to a weight of 1 m ² . The thickness of the convex part 11 and the recessed part 12 cut out the sheet | seat base material 10 to the dimension of 100 mm x 100 mm, and used the laser thickness meter (Keyence Corporation, LK-085), and the convex part 11 and the recessed part 12 part in this The thickness is measured at N = 10 and averaged. The correlation between the measurement value of the laser thickness meter and the thickness measurement value under 20 gf / cm ² load [y = 1.3036x−0.4814, y: thickness (mm) under 20 gf / cm ² load, x : Thickness with laser (mm)], converted to a thickness under a load of 20 gf / cm ² . The apparent density is obtained by dividing the obtained basis weight by the thickness under a load of 20 gf / cm ² .

  The sheet base material 10 preferably has a saturated liquid amount of 50 to 1000%, particularly 100 to 600% per unit weight. As a result, a sufficient amount of liquid can be retained. The amount of the saturated liquid depends on the space formed by the fibers constituting the sheet base material 10 and the material of the fibers themselves. Therefore, simply reducing the thickness of the sheet substrate 10 does not improve the liquid holding performance, and it is necessary to consider the amount of saturated liquid in order to improve the performance. The amount of the saturated liquid is obtained by cutting the sheet substrate 10 into a size of 100 mm × 100 mm and measuring its weight. It can be determined by immersing the sheet base material in ion exchange water for 15 minutes or more, dipping or dropping the liquid for 1 minute or more after removal, measuring the weight, and calculating the difference in weight before and after immersion.

  Next, the preferable manufacturing method of the fiber sheet which comprises the sheet base material 10 of this embodiment is demonstrated, referring FIG. FIG. 2 schematically shows a preferred apparatus 20 for producing fiber sheets. The apparatus 20 includes a web forming unit 21, a hydroentanglement unit 22, and a pattern providing unit 23. The web forming unit 21 is provided with a card machine 21A. The card web 10A is fed out from the card machine 21.

  The fed card web 10A is conveyed to the water entangling unit 22. The water flow entanglement unit 22 includes a high-pressure jet water flow injection device 22A and a water-permeable endless mesh belt 22B. The endless mesh belt 22B is disposed at a position facing the ejection port of the ejection device 22A, and circulates in the conveying direction of the card web 10A. The constituent fibers of the card web 10A are entangled by the high-pressure jet water stream injected from the injection device 22A, and the card web 10A becomes a spunlace nonwoven fabric 10B as a fiber sheet.

The water pressure condition when the web 10A is hydroentangled is not particularly limited. For example, when the basis weight of the web is 20 to 150 g / m ² , the water pressure is preferably 3 to 35 MPa, more preferably 10 to 30 MPa, and particularly preferably 15 to 25 MPa. Hydroentanglement may be performed several times according to the purpose. The water pressure may be applied from the front or back of the web, or from both sides. Further, the water pressure may be adjusted in several stages, and in that case, the maximum water pressure may be adjusted to the above-described water pressure.

  The spunlace nonwoven fabric 10 </ b> B thus obtained is conveyed to the pattern applying unit 23. The pattern imparting unit 23 includes an injection device 23A for high-pressure jet water flow and a pattern imparting member 23B. The pattern applying member 23B is disposed at a position facing the injection port of the injection device 23A, and circulates in the conveyance direction of the spunlace nonwoven fabric 10B. The pattern imparting member 23B is configured by, for example, a water-permeable endless belt provided with a large number of openings (not shown) corresponding to the convex portions 11 shown in FIG. As the pattern imparting member 23B, for example, a plate made of stainless steel or plastic with a circular, square, rectangular, rhombus or the like opened, or made of stainless steel or plastic having an opening (hole) of about 5 to 40 mesh. You may use what was provided with the net | network. The way of weaving the net is not particularly limited, but 1/1 plain weave, 1/2 twill weave, silk weave, etc. are used.

  In the pattern imparting unit 23, a high-pressure jet water stream is ejected from the ejection device 23A toward the nonwoven fabric 10B while the spunlace nonwoven fabric 10B is placed on the pattern imparting member 23B. The spunlace nonwoven fabric 10B located at the opening portion of the pattern application member 23B receives the water pressure of the high-pressure jet water stream while being pressed against the pattern application member 23B. As a result, the convex part 11 which is a site | part with small consolidation is formed in the spunlace nonwoven fabric 10B. On the other hand, the spunlace nonwoven fabric 10B that is not located at the opening portion of the pattern application member 23B receives the water pressure of the high-pressure jet water stream while being pressed against the pattern application member 23B. As a result, the convex part 11 which is a part with small consolidation is formed with a concave part 12 which has a shape reversed in front and back and is consolidated. Thus, the target sheet substrate 10 is obtained.

  The fiber sheet constituting the sheet base 10 may be further embossed and consolidated. Consolidation may be partial or full surface. By embossing the convex portion 11 and the concave portion 12, the portion that has been consolidated by embossing has a higher apparent density and a smaller interfiber distance. This is preferable because resistance to liquid movement is further increased. In particular, since the apparent density of the concave portion 12 is originally increased by consolidation, by performing embossing in accordance with the position of the concave portion 12, the consolidated portion is compared with the portion of the concave portion 12 that is not embossed. Thinner, higher apparent density and smaller interfiber distance. This is preferable because resistance to liquid movement is further increased.

There is no restriction | limiting in particular in the method of embossing, For example, roll embossing, flat plate embossing, ultrasonic embossing, patterning punch embossing etc. are mentioned. The embossing conditions are not particularly limited, and are appropriately adjusted according to the purpose. For example, embossing may be performed by applying heat. The shape of embossing may be arbitrary, for example, a square, a rectangle, a circle, an ellipse, a rhombus, a line or the like. Specifically, in the case of ultrasonic embossing, a sheet having a staggered dot pattern can be obtained by passing a fiber sheet between an engraving roll having the following specifications and an ultrasonic horn.
Engraving roll specifications: (emboss formation convex part on roll surface) 2 mm diameter dot pattern, (emboss formation convex part) Vertical and horizontal center pitch values are 7 mm, staggered arrangement, (embossing area ratio described later) 12.8%

  The area ratio of embossing is preferably 1 to 30%, and particularly preferably 5 to 25% from the viewpoint of increasing resistance to liquid movement and securing sufficient thickness and flexibility. The area ratio of embossing is measured by the following method. The film for pressure distribution measurement (Fuji Film Co., Ltd., trade name: Prescale, film whose red color density changes according to the strength of the applied pressure) is pressed against the embossing roll, and the part that comes into contact with the embossing convex part is the film. Color red on top. Under this condition, the diameter of the embossing projections is measured with a digital microscope (Keyence Corporation, VHX-500), and the ratio of the total area of the embossing projections to the area of a certain range of the fiber sheet is calculated. calculate. This value is the area ratio for embossing.

  The sheet substrate 10 is impregnated with various liquids to form a wet sheet. As the kind of liquid to be impregnated, an appropriate one is selected according to the specific use of the wet sheet. For example, when a wet sheet is used as a makeup remover sheet, an aqueous liquid containing a surfactant, an O / W emulsion emulsion, a W / O emulsion emulsion, an oil gel, cream, or oil can be used as the liquid. . In particular, an aqueous solution containing a nonionic surfactant and glycerin is preferable, and the nonionic surfactant is preferably polyethylene glycol monolaurate. For the purpose of washing aqueous and oily makeup cosmetics with high skin adhesion such as mascara, an oil-based agent 5 having an aqueous thickener 0.01 to 0.5% by mass and a boiling point of 160 to 300 ° C. An O / W emulsion emulsion containing 30% by weight and water is preferable, and an O / W emulsion emulsion in which the oil is isoparaffin having a boiling point of 160 to 300 ° C. is more preferable. As the isoparaffin, commercial products such as Margazole R (Maruzen Petrochemical Co., Ltd.) and IP Solvents 1620 and 2028 (Idemitsu Petrochemical Co., Ltd.) can be used.

  The amount of liquid impregnated into the sheet base material depends on the specific use of the wet sheet, but is preferably 100 to 600%, particularly 200 to 450% per unit weight of the sheet base material.

Even if the wet sheets obtained in this way are stored in a stack of plural sheets, the movement of the liquid is suppressed. By impregnating the liquid, the apparent density of the sheet in the wet sheet is different from the apparent density of the sheet in the sheet base material before impregnating the liquid, but there is no great difference in the apparent density of both sheets.
Therefore, the movement of the liquid in the wet sheet is suppressed.

  The wet sheet provided with the sheet base material of the present invention is suitably used for various wiping applications for people, animals, and objectives. For example, it is suitably used as a makeup remover sheet, an antiperspirant sheet, a wiping cloth, a pet wiping sheet, a floor wiping sheet, and the like.

  As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to the said embodiment. For example, the shape of the convex part 11 and the recessed part 12 in the sheet | seat base material 10, and those arrangement | positioning patterns are good also as things other than shown in FIG. Specifically, in the above-described embodiment, the convex portions 11 are arranged in a row at a predetermined interval in one direction of the sheet base material 10, the rows are arranged in multiple rows, and the convex portions in each row. 11 is formed so as to be shifted by a half pitch, but the convex portion 11 may be disposed by a shift other than a half pitch.

  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. Unless otherwise specified, “%” means “% by weight”.

[Example 1]
The sheet | seat base material shown in FIG. 1 was manufactured using the apparatus shown in FIG. A cotton having a fiber diameter of 1.7 dtex was used as a raw material, and a web having a basis weight of 61.1 g / m ² was produced by a card machine. The obtained web was entangled with a high-pressure water stream to obtain a spunlace nonwoven fabric containing water. The water flow pressure was 7 MPa. The water-containing spunlace nonwoven fabric was pattern-assigned by a high-pressure water stream using a pattern-applying member. The water flow pressure was 18 MPa. As the pattern imparting member, a stainless plate was used, the opening was circular, and the diameter was 3 mm. The openings were arranged in a line at a predetermined interval along the circulation direction of the pattern applying member, and the lines were arranged in multiple lines in a direction orthogonal to the rotation direction. In each row, the arrangement positions of the holes were shifted by a half pitch. The distance between the centers of adjacent apertures in the circumferential direction was 4 mm. The distance between the centers of the apertures between adjacent rows was 4 mm. Thus, the target sheet base material was obtained. The obtained sheet base material was impregnated with a cleaning liquid having a formulation shown in Table 1 below as a cleaning liquid to obtain a wet sheet. The impregnation rate of the cleaning liquid was 350%.

[Example 2]
In Example 1, as the pattern imparting member, a stainless plate was used, the opening was made circular, and the diameter was 6 mm. In addition, the distance between the centers of adjacent openings in the circumferential direction was 8.5 mm, and the distance between the centers of the openings between adjacent rows was 8.5 mm. Except these, it carried out similarly to Example 1, and obtained the sheet | seat base material and wet sheet of basic weight 55.7g / m < ² >.

Example 3
In Example 1, the pattern imparting member was made of stainless steel 5 mesh net (plain weave, open holes were square, and one side of the aperture was 4 mm long). In addition, the distance between the centers of the adjacent holes in the circumferential direction was 5 mm, and the distance between the centers of the openings between adjacent rows was 5 mm. Except these, it carried out similarly to Example 1, and obtained the sheet | seat base material and wet sheet of basic weight 55.9g / m < ² >.

[Comparative Example 1]
In Example 1, a sheet substrate and a wet sheet having a basis weight of 61.1 g / m ² were obtained in the same manner as in Example 1 except that no pattern was applied to the spunlace nonwoven fabric.

[Evaluation]
About the sheet | seat base material obtained by the Example and the comparative example, the ratio of the area of a recessed part with respect to the area of a sheet base material, the ratio of the area of a convex part, bulk softness, the distance between fibers in a convex part and a recessed part, thickness, and an apparent density Was measured. The results are shown in Table 2 below. In addition, the wet sheets obtained in Examples and Comparative Examples were evaluated for the difference in impregnation rate before and after storage, the feel, and the cleaning power by the following methods. Furthermore, comprehensive evaluation was also performed. These results are also shown in Table 2 below.

[Difference in impregnation rate before and after storage]
The sheet substrate was cut into a size of 100 mm in length and 150 mm in width, and impregnated with the cleaning liquid having the formulation shown in Table 1 above. The impregnation rate was 350%. The 40 wet sheets thus obtained were C-folded (length 100 mm × width 77 mm, C-folded portion was opened 4 mm without overlapping), laminated, sealed in a pillow bag, and stored at 50 ° C. for 1 month. After storage, it was left to return to room temperature. The wet sheet was taken out from the pillow bag, and the impregnation rate of each of the second sheet from the top and the 39th sheet from the top was measured. The difference between the two was calculated, and the value was defined as the difference between the upper and lower impregnation rates. Further, the difference in the impregnation rate between the second and 39th sheets before and after storage was also obtained. Note that the lowermost sheet and the uppermost sheet were not measured because they may be affected by the pillow bag. The impregnation rate was calculated from the following equation by measuring the weight of each wet sheet, washing the sheet with a detergent, rinsing with distilled water, and then measuring the weight of the dried sheet.
Impregnation rate (%) = (wet sheet weight−dry sheet weight) × 100 / dry sheet weight

Evaluation: Second and 39th sheets ◎: The difference in impregnation rate after storage with respect to the impregnation rate immediately after preparation is within ± 25% ○: Within ± 40% △: Within ± 60% ×; Same as above ± 60% ・ About difference in impregnation rate after storage of second and 39th sheet ◎; Within ± 25% ○; Within ± 40% △; Within ± 60% ×; Greater than ± 60%

[Feel]
Ten faces were wiped with a wet sheet, and sensory evaluation was performed on the feel of the skin.
Evaluation ◎; 8 or more out of 10 responded that the touch was good.
○: 6 to 7 out of 10 responded that the feel was good.
Δ: 4 to 5 out of 10 responded that the feel was good.
×: Less than 3 people answered that 10 people feel good

[Detergency]
For the evaluation of the cleaning power, lipstick stains were used among general makeup stains.
[Evaluation of lipstick detergency]
A certain amount of lipstick (trade name Orb lipstick RS151, manufactured by Kao Corporation) is applied in a straight line to a length of 10 mm × 30 mm on the inner side of the lower arm. Each wet sheet with an impregnation rate of 350% was applied on the lipstick stain, and wiped in one direction to be wiped off. The number of times until complete wiping was measured with N number = 2 and averaged.
Evaluation ◎; Less than 4 times ○; 4 times or more and 7 times or less △; 8 times or more and 10 times or less ×; 11 times or more

〔Comprehensive evaluation〕
The following criteria were evaluated for five items: difference in impregnation rate before and after storage of the second sheet, difference in impregnation ratio before and after storage of the 39th sheet, difference in impregnation ratio of the second and 39th sheets, feel, and cleaning power.
◎; 3 or more ◎; ◎ 2 △; ◎ 1 x; ◎ 0

  As is apparent from the results shown in Table 2, the wet sheet using the sheet base material of the example is impregnated with the second sheet and the 39th sheet as compared with the wet sheet using the sheet base material of the comparative example. It can be seen that the difference between the two is small and the movement of the liquid is suppressed. Moreover, it turns out that the wet sheet | seat using the sheet | seat base material of each Example is favorable in touch, and is excellent in the detergency. Although not shown in Table 2, the area ratio of the protrusions in the sheet base material and the area ratio of the protrusions in the wet sheet were substantially the same.

Fig.1 (a) is a schematic diagram which shows one Embodiment of the sheet | seat base material for wet sheets of this invention, FIG.1 (b) is the bb sectional view taken on the line in Fig.1 (a). FIG. 2 is a schematic view showing an apparatus suitably used for producing the sheet base material shown in FIG.

Explanation of symbols

10 Sheet base material for wet sheet 11 Convex part 12 Concave part

Claims (9)

A sheet base material for a wet sheet that is impregnated with a liquid to form a wet sheet,
The sheet base material comprises a single-layer fiber sheet containing 55% by weight or more of one or more hydrophilic fibers,
The fiber sheet has a concave portion in which fibers are consolidated and a convex portion having a lower degree of fiber consolidation than the concave portion, and the area ratio of the concave portion defined below is 30 to 80%. ,
The hydrophilic fibers Ri fiber diameter is 0.1~5.5dtex der,
The apparent density of the projections is 0.05~0.20g / cm ^3, an apparent density of the recess is greater than the apparent density of the convex portion, and a 0.10~0.30g / cm ^3,
The thickness of the convex portion is 0.3 to 0.7 mm, the thickness of the concave portion is smaller than the thickness of the convex portion, and is 0.2 to 0.5 mm,
The inter-fiber distance in the concave portion is 10 to 40 μm, the inter-fiber distance in the convex portion is larger than the inter-fiber distance in the concave portion, and is 20 to 50 μm,
The amount of saturated liquid measured by the following method is 100 to 600% per unit weight,
The convex portion and the wet sheet sheet substrate the recess that is formed in the fiber sheet so that the contact area ratio with respect to the plane in which the liquid is defined below in the state of being impregnated is 20 to 70%.
The area ratio of the recess means the ratio of the total area of the recess to the area of the fiber sheet when the fiber sheet is viewed in plan.
The amount of the saturated liquid is cut out into a size of 100 mm × 100 mm and the weight is measured, and then the sheet base material is immersed in ion-exchanged water for 15 minutes or more, and after taking out, the liquid is dropped or dropped for 1 minute or more, It is determined by measuring the weight and calculating the difference in weight before and after immersion.
The contact area ratio with respect to the plane refers to the ratio of the area of the portion where the sheet substrate is in contact with the plane with respect to the area of the sheet substrate. The sheet substrate according to claim 1 , wherein the fiber sheet is made of a spunlace nonwoven fabric. Sheet substrate according to claim 1 or 2 basis weight of said fibrous sheet is 20 to 150 g / m ^2. The sheet base material according to any one of claims 1 to 3 , wherein the fiber sheet has a bulk softness of 0.1 to 1.0 N. The sheet base material according to any one of claims 1 to 4 , wherein a large number of individually independent convex portions are surrounded by the concave portions. A wet sheet obtained by impregnating a sheet base material according to any one of claims 1 to 5 with a liquid. A method for producing a sheet base material for a wet sheet according to any one of claims 1 to 5 ,
A card web fed from a card machine is hydroentangled to form a fiber sheet, the fiber sheet is arranged on a pattern imparting member having an opening, and a high-pressure water stream is jetted toward the fiber sheet,
The fiber sheet positioned at the opening portion in the pattern application member receives the water pressure of a high-pressure water flow while being pressed against the pattern application member, thereby forming the convex portion on the fiber sheet.
A method for producing a sheet base material for a wet sheet. A wet sheet laminate comprising a plurality of wet sheets obtained by impregnating the sheet base material for wet sheets according to any one of claims 1 to 5 with 100 to 600% liquid per unit weight of the sheet base material. body. The wet sheet laminate according to claim 8, wherein the liquid is an aqueous liquid containing a surfactant, an O / W emulsion emulsion, a W / O emulsion emulsion, an oil gel, cream or oil.

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