JP5738144B2 - Nonwoven fabric for wet tissue - Google Patents

Description

  The present invention relates to a nonwoven fabric for wet tissue.

  Forming a layer with the hydrophobic and hydrophilic characteristics of the fibers in the cross-sectional direction of the nonwoven fabric, and improving the stability of taking out by giving water to the intermediate layer, and when wiping off, an appropriate amount of moisture comes out to be wiped off There is known a wet tissue laminate that does not leave much moisture in an object (Patent Document 1).

Japanese Patent No. 3183818

  However, in the invention of Patent Document 1, if the hydrophobic level of the layer is increased due to the characteristics of the wet tissue, slippage between the sheets occurs and the wiping operation is hindered. It was not possible to build a structure to store clear water. Further, as a method of fixing the layers, fiber entanglement by physical energy such as spunlace is used, so that the layers are ambiguous and it is difficult to clearly show the layer structure. Furthermore, it was not possible to show that it was a layer visually. In addition, there is a problem that it cannot be wiped off with plenty of water and the remaining amount of wiping cannot be reduced.

The present invention is a nonwoven fabric for wet tissue containing absorbent fibers,
A plurality of first ridges, first grooves, second ridges and second grooves extending in the same direction are formed on at least one surface of the nonwoven fabric,
The height of the top of the first ridge is higher than the height of the top of the second ridge,
The height of the top of the second ridge is higher than the height of the bottom of the second groove,
The height of the bottom of the second groove is higher than the height of the bottom of the first groove,
A first groove is located between two adjacent first ridges;
A plurality of second ridges and second grooves are located between two adjacent first ridges where the first groove is not located,
An interval between two first ridges adjacent to each other across the first groove is wider than an interval between two second ridges adjacent to each other across the second groove.
Preferably, the apparent density in the dry state of the nonwoven fabric in the region where the first wrinkles and the first grooves are located is smaller than the apparent density in the dry state of the region where the second wrinkles and the second grooves are located.
Preferably, the difference between the height of the top of the first ridge and the height of the top of the second ridge is 0.1 mm or more.
Preferably, the absorbent fiber includes cellulose.
Preferably, the nonwoven fabric can visually confirm the liquid holding portion and the non-holding portion at the time of liquid impregnation.
Preferably, 30% or more of the fibers constituting the nonwoven fabric are absorbent fibers.
Preferably, the apparent density in the dry state of the nonwoven fabric in the region where the first ridge and the first groove are located is 0.30 to 0.10 g / cm ³ , and the second ridge and the second groove are located. The apparent density in the dry state of the nonwoven fabric in the region is 0.12 to 0.20 g / cm ³ .
Preferably, the interval between two first ridges adjacent to each other across the second ridge and the second groove is 3 mm or more.
Preferably, the fiber length of the fibers constituting the nonwoven fabric is 20 mm or less.
Preferably, the difference between the height of the top of the second ridge and the height of the bottom of the second groove is 0.05 to 0.10 mm.
Preferably, an interval between two second ridges adjacent to each other with the second groove interposed is 0.3 to 1.0 mm.
Preferably, the difference between the height of the top of the first ridge and the height of the bottom of the first groove is 0.15 to 0.60 mm.
Preferably, a third ridge is formed between two adjacent first ridges where the second ridge and the second groove are not located, and the height of the top of the third ridge is the second height. It is higher than the top of the ridge.
Preferably, the first ridge and the first groove are formed by jetting water vapor, and the second ridge and the second groove are formed by jetting water flow.

The present invention is also a method for producing the nonwoven fabric for wet tissue,
Supplying a mixture of fibers containing absorbent fibers and water onto a support to form a water-containing web on the support;
A step of injecting a water flow onto the web from water flow nozzles arranged at equal intervals in the width direction of the web to entangle the fibers;
The method includes a step of spraying water vapor onto a web from which water flow has been jetted from a water vapor nozzle arranged side by side in the width direction of the web at intervals wider than the interval between the water flow nozzles, and a step of drying the web from which water vapor has been jetted.

  The present invention is also a wet tissue obtained by impregnating the nonwoven fabric with a liquid.

  Since the nonwoven fabric for wet tissue of the present invention has rough ridge grooves (first ridge and first groove) and fine ridge grooves (second ridge and second groove), the coarse grooves remove relatively large dirt. Entanglement and relatively small dirt can be entangled with fine grooves. That is, according to the present invention, it is possible to remove from coarse dirt to fine dirt at a time with one sheet.

FIG. 1 is a schematic enlarged perspective view of the nonwoven fabric of the present invention. FIG. 2 is a schematic enlarged cross-sectional view of a nonwoven fabric according to another embodiment of the present invention. FIG. 3 is a diagram showing an example of a nonwoven fabric manufacturing apparatus for manufacturing the nonwoven fabric of the present invention. FIG. 4 is a diagram illustrating an example of the water flow nozzle. FIG. 5 is a diagram for explaining the principle that the fibers of the web are entangled by the water jet. FIG. 6 is a cross-sectional view in the width direction of the web on which the water flow is jetted. FIG. 7 is a diagram illustrating an example of a water vapor nozzle. FIG. 8 is a view for explaining the principle that fibers of a web are loosened and grooves and wrinkles are formed by steam injection. FIG. 9 is a diagram showing another example of a nonwoven fabric manufacturing apparatus for manufacturing the nonwoven fabric of the present invention. FIG. 10 is a diagram illustrating another example of the water vapor nozzle. FIG. 11 is a photograph (wet state) of the water jet surface of the web after jetting the water flow in Example 1. FIG. 12 is a photograph (wet state) of the water vapor jet surface of the web after the water vapor is jetted in Example 1. FIG. 13 is a photograph of the water vapor jet surface of the nonwoven fabric (dried state) obtained in Example 1. FIG. 14 is a photograph of the water vapor jet surface of the nonwoven fabric (dried state) obtained in Example 3.

  Hereinafter, the present invention will be described with reference to the drawings, but the present invention is not limited to those described in the drawings.

FIG. 1 is a schematic enlarged perspective view of the nonwoven fabric of the present invention.
In the nonwoven fabric 1 of the present invention, a plurality of first ridges 3, first grooves 4, second ridges 5 and second grooves 6 extending in the same direction Y are formed on at least one surface. The height h ₃ of the top portion 3T of the first ridge is higher than the height h ₅ of the top portion 5T of the second ridge, and the height h ₅ of the top portion 5T of the second ridge is the height 6 of the bottom portion 6B of the second groove. higher than the height h _6, the height h ₆ of the second groove in the bottom 6B is greater than the height h ₄ of the bottom 4B of the first groove. Here, the height means a height perpendicular to the direction of the one surface from the surface opposite to the one surface. When the opposite surface has a ridge groove, the heights h ₃ , h ₄ , h ₅ , and h ₆ refer to the height from the top of the most protruding ridge on the opposite surface. The first groove 4 is located between the two adjacent first ridges 3 and 3. A plurality of second ridges 5 and second grooves 6 are located between two adjacent first ridges 3 and 3 where the first groove 4 is not located. A distance d ₃ between two first ridges 3 and 3 adjacent to each other across the first groove 4 is wider than a distance d ₅ between two second ridges adjacent to each other across the second groove.

  That is, the nonwoven fabric of the present invention has rough ridges (first ridge and first groove) and fine ridges (second ridge and second groove) on at least one surface. A relatively large dirt can be entangled with a rough groove, and a relatively small dirt can be entangled with a fine groove. That is, according to the present invention, it is possible to remove from coarse dirt to fine dirt at a time with one sheet.

The difference (h ₃ −h ₅ ) between the height h ₃ of the top of the first ridge and the height h ₅ of the top of the second ridge is preferably 0.1 mm or more, more preferably 0.12 It is -0.70mm, More preferably, it is 0.15-0.50mm. If the difference (h ₃ -h ₅ ) is too small, the scraping ability of the dirt will be poor, and it will be difficult to be bulky. Conversely, if the difference is too large, the damage to the sheet will be great, and the sheet strength will be reduced. Fibers are easy to come off.

The distance d ₃ between the two first ridges 3 and 3 adjacent to each other with the second ridge 5 and the second groove 6 in between is preferably 3 mm or more, more preferably 4.0 to 8.0 mm. More preferably, it is 4.5 to 6.0 mm. When the interval d ₃ is too small, that is the second ridges and the second grooves to form a region R ₂ situated difficult. Conversely, if the interval d ₃ is too large, the number of furrows is reduced, or worse scraping of stains, it is difficult to maintain bulkiness.

The difference (h ₅ −h ₆ ) between the height h ₅ of the top of the second ridge and the height h ₆ of the bottom of the second groove is preferably 0.05 to 0.10 mm, more preferably It is 0.06-0.09 mm, More preferably, it is 0.07-0.08 mm. If the difference (h ₅ -h ₆ ) is too small, it becomes paper-like and the touch becomes hard. On the other hand, if the difference (h ₅ -h ₆ ) is too large, the contact area becomes small and the finish wiping effect is deteriorated. The heights h ₃ , h ₄ , h ₅ , and h ₆ can be obtained from a cross-sectional micrograph.

The distance d ₅ between the two second flanges _{5 and} 5 adjacent to each other across the second groove 6 is preferably 0.3 to 1.0 mm, more preferably 0.4 to 0.8 mm. More preferably, it is 0.5 to 0.7 mm. Difficult to form irregularities when the distance d ₅ is too small, and an excessively large can weak portions of fiber entanglement, sheet strength variation occurs to a considerable extent.

The difference (h ₃ −h ₄ ) between the height h ₃ of the top of the first ridge and the height h ₄ of the bottom of the first groove is preferably 0.15 to 0.60 mm, more preferably It is 0.17-0.55 mm, More preferably, it is 0.20-0.50 mm. If the difference (h ₃ -h ₄ ) is too small, the effect of entanglement with dirt is lowered. On the other hand, if the difference is too large, it is difficult to maintain the shaped shape or the amount of fiber loss increases.

In one aspect of the present invention, the apparent density in the dry state of the nonwoven fabric region R ₁ of the first ridges and the first groove position, region R ₂ where the second ridges and the second grooves are located It is smaller than the apparent density in the dry state.
Apparent density in the dry state of the nonwoven fabric region _{R 1} of the first ridges and the first groove is located is preferably 0.030~0.10g / cm ^3, more preferably 0.04~0.09g / Cm ³ , more preferably 0.05 to 0.08 g / cm ³ . When the apparent density of the region R ₁ is too small, easily easily sag small, the number of fibers projecting portion too, and an excessively large number of fibers is too much, resistance wiping becomes dirty hardly enter is deteriorated.
Apparent density in the dry state of the second ridge and a second region _{R 2} having grooves positioned nonwoven is preferably 0.12~0.20g / cm ^3, more preferably 0.13~0.19g / Cm ³ , more preferably 0.14 to 0.18 g / cm ³ . When the apparent density of the region R ₂ is too small, the contact area is wiping fried becomes rough small, not suitable for wiping finish, and an excessively large, tends to become paper-like, tactile becomes hard easily.

The nonwoven fabric according to a preferred embodiment of the present invention has a region R ₂ having a large apparent density and a region R ₁ having a small apparent density. Therefore, when the liquid is impregnated, a large amount of the liquid gathers in the region R ₂ having a large apparent density. the small regions R ₁ liquor not much there. That is, the nonwoven fabric of the preferable aspect of this invention can visually confirm a liquid holding part and a non-holding part at the time of liquid impregnation. Examples of the liquid include a mixed solution of preservatives such as distilled water, propylene glycol, and paraben. If the liquid is, for example, water, the water between the fibers concentrates on the small ridge due to the density gradient, and there is no water in the large ridge, so that the water that comes out of the small ridge when wiping the object is removed. The dirt can be lifted off, and the dirt can be wiped off without leaving much moisture on the surface to be wiped by sucking up water with a large ridge.

  The first ridge 3 and the first groove 4 can be formed by injecting water vapor, and the second ridge 5 and the second groove 6 can be formed by injecting water flow, Details of the method will be described later.

FIG. 2 shows a schematic enlarged cross-sectional view of a nonwoven fabric according to another embodiment of the present invention. In the nonwoven fabric shown in FIG. 2, a third ridge 7 is further formed between two adjacent first ridges 3 and 3 where the second ridge 5 and the second groove 6 are not located. In the embodiment shown in FIG. 2, two third ridges 7 are formed between two adjacent first ridges 3, 3, but may be one or three or more. When two or more third ridges 7 are formed between two adjacent first ridges 3, 3, a third groove 8 is provided between two adjacent third ridges 7. Exists. The height h ₇ of the top portion 7T of the third ridge 7 is higher than the height h ₅ of the top portion 5T of the second ridge 5. Third height h ₇ of the top portion 7T of the ridge 7 may be the same as the height h ₃ of the top 3T of the first ridges 3 may be different. Preferably, the top height h ₇ of 7T of the third ridges 7 are the same as the height h ₃ of the top 3T of the first ridges 3. The height h ₈ of the bottom section 8B of the third groove 8 is the same as the height h ₄ also may the first groove 4 in the bottom 4B, may be different. Preferably, the height h ₈ of the bottom section 8B of the third groove 8 is the same as the height h ₄ of the bottom 4B of the first groove 4.

The nonwoven fabric of this invention contains an absorptive fiber.
Preferably, 30% or more of the fibers constituting the nonwoven fabric are absorbent fibers, more preferably 35% or more are absorbent fibers, and even more preferably 40% or more are absorbent fibers. All of the fibers constituting the nonwoven fabric may be absorbent fibers.
Absorbable fibers that can be used in the present invention include soft pulp and hardwood chemical pulp, wood pulp such as semi-chemical pulp and mechanical pulp, mercerized pulp and crosslinked pulp obtained by chemically treating these wood pulp, hemp and cotton, etc. Non-wood fibers, cellulosic fibers such as regenerated fibers such as rayon fibers, and polyvinyl alcohol fibers. The absorbent fiber preferably comprises cellulose.
Examples of fibers other than absorbent fibers include synthetic fibers such as polyethylene fibers, polypropylene fibers, polyester fibers, and polyamide fibers.

  The fiber length of the fibers constituting the nonwoven fabric is preferably 20 mm or less, more preferably 1 to 15 mm, and even more preferably 2 to 12 mm. If the fiber length is too long, it is difficult to disperse uniformly in water, and the texture tends to deteriorate. On the other hand, if the fiber length is too short, the yield at the time of papermaking deteriorates, and it is difficult to hydroentangle and the strength tends to be low.

The nonwoven fabric of the present invention is
Supplying a mixture of fibers containing absorbent fibers and water onto a support to form a water-containing web on the support;
A step of injecting a water flow from a water flow nozzle arranged at equal intervals in the width direction of the web (a direction perpendicular to the direction of travel of the web) to entangle the fibers,
By a method including a step of spraying water vapor onto a web sprayed with a water flow from a water vapor nozzle arranged side by side in the width direction of the web at intervals wider than the interval between the water flow nozzles, and a step of drying the web sprayed with water vapor Can be manufactured.

Hereafter, the manufacturing method of the nonwoven fabric of this invention is demonstrated in detail.
FIG. 3 is a diagram showing an example of a nonwoven fabric manufacturing apparatus for manufacturing the nonwoven fabric of the present invention.

  First, a mixture of fibers containing absorbent fibers and water is supplied onto the support of the web forming conveyor 16 by the raw material supply head 11 and deposited on the support. The support preferably has air permeability through which water vapor can pass. For example, a wire mesh, a blanket, etc. can be used for the support.

  The fibers containing water deposited on the support are appropriately dehydrated by the suction box 13 to form the web 30. The web 30 includes two water nozzles 12 disposed on the support, and two water nozzles 12 that are disposed at positions facing the water nozzle 12 across the support to collect water sprayed from the water nozzle 12. It passes between the suction box 13. At this time, the web 30 is sprayed with a high-pressure water flow from the water flow nozzle 12, and a second ridge and a second groove are formed in the web 30.

  An example of the water flow nozzle 12 is shown in FIG. The water nozzle 12 injects a plurality of water streams 31 arranged in the width direction (CD) of the web 30 toward the web 30. As a result, the web 30 is formed with a plurality of grooves 32 aligned in the width direction of the web 30 and extending in the machine direction (MD). The groove 32 corresponds to the second groove 6.

  Moreover, when the web 30 receives a water flow, the groove | channel 32 will be formed in the web 30 as mentioned above, and the fiber of the web 30 will be entangled, and the intensity | strength of the web 30 will become high. The principle that the fibers of the web 30 are entangled when the web 30 receives a water flow will be described with reference to FIG. 5, but this principle does not limit the present invention.

  As shown in FIG. 5, when the water flow nozzle 12 ejects the water flow 31, the water flow 31 passes through the support body 41. Thereby, the fibers of the web 30 are drawn around the portion 42 where the water flow 31 passes through the support body 41. As a result, the fibers of the web 30 gather toward the portion 42 where the water flow 31 passes through the support body 41, and the fibers are entangled.

  When the fibers of the web 30 are entangled with each other, the strength of the web 30 is increased, so that in a later step, even when water vapor is sprayed onto the web 30, holes are not opened, broken, or blown away. . Further, the wet strength of the web 30 can be increased without adding a paper strength enhancer to the raw material.

The water flow ejected from the water flow nozzle 12 is a high-pressure water flow.
The amount of energy of the water flow when the water flow is jetted onto the web 30 is preferably 0.125 to 1.324 kW / m ² .
The amount of energy in the water stream is calculated from the following equation.
Energy amount of water flow (kW / m ² ) = 1.63 × injection pressure (Kg / cm ² ) × injection flow rate (m ³ / min) / treatment time (m / min) / 60
Here, injection flow rate (m ³ / min) = 750 × total orifice opening area (m ² ) × injection pressure (Kg / cm ² ) ^0.495
If the energy amount of the water stream is smaller than 0.125 kW / m ² , the strength of the web 30 may not be so strong. Moreover, when the energy amount of a water flow is larger than 1.324 kW / m < ² >, the web 30 will become hard too much and the volume of the web 30 may not become so high with the below-mentioned high pressure steam.

  The distance between the tip of the water flow nozzle 12 and the upper surface of the web 30 is preferably 5.0 to 20.0 mm. If the distance between the tip of the water flow nozzle 12 and the upper surface of the web 30 is less than 5.0 mm, the web texture is likely to be disturbed by the high pressure water flow, and the fibers that bounce off due to the water flow adhere to the nozzle. There may be a problem that it is easy. Moreover, when the distance between the front-end | tip of the water flow nozzle 12 and the upper surface of the web 30 is larger than 20.0 mm, processing efficiency may fall remarkably and the problem that fiber entanglement may become weak may arise.

  The hole diameter of the water flow nozzle 12 is preferably 90 to 150 μm. If the hole diameter of the water flow nozzle 12 is too small, there may be a problem that the nozzle is likely to be clogged. Moreover, when the hole diameter of the water flow nozzle 12 is too large, the problem that processing efficiency worsens may arise.

  It is preferable that the hole pitch of the water flow nozzle 12 (the distance between the centers of adjacent holes) is 0.3 to 1.0 mm. If the hole pitch of the water flow nozzle 12 is too small, the pressure resistance of the nozzle may be reduced, causing a problem of breakage. Moreover, when the hole pitch of the water flow nozzle 12 is too large, the problem that fiber entanglement becomes insufficient may arise.

  A cross section in the width direction of the web 30 after passing between the two water flow nozzles 12 and the two suction boxes 13 is shown in FIG. A second ridge and a second groove are formed on the upper surface of the web 30 by the high-pressure water flow. Depending on the water jet conditions, a similar groove is formed on the surface opposite to the water jet surface (not shown).

  Next, the web 30 sucks the water vapor sprayed from the water vapor nozzle 14 disposed at a position facing the water vapor nozzle 14 with the support interposed between the two water vapor nozzles 14 disposed on the support. It passes between the two suction boxes 13. At this time, the web 30 is sprayed with water vapor from the water vapor nozzle 14, and the first ridge 3 and the first groove 4 are formed on the upper surface (the surface on the water vapor nozzle 14 side). When the nonwoven fabric manufacturing apparatus shown in FIG. 3 is used, the surface of the web on which the water vapor is injected is the same surface as the surface on which the water flow is injected. Depending on the water jet conditions, a groove is also formed on the surface opposite to the water jet surface, but if a groove is also formed on the surface opposite to the water jet surface, You may inject water vapor | steam to the surface on the opposite side to a water-flow injection surface.

  An example of the water vapor nozzle 14 is shown in FIG. The water vapor nozzle 14 injects a plurality of water vapors 51 arranged in the width direction (CD) of the web 30 toward the web 30. As a result, a plurality of grooves 52 are formed on the upper surface of the web 30 and extend in the machine direction (MD) in the width direction of the web 30. The groove 52 corresponds to the first groove 4.

  The principle that the first ridge 3 and the first groove 4 are formed when water vapor is sprayed onto the web 30 will be described with reference to FIG. 8, but this principle does not limit the present invention.

  As shown in FIG. 8, when the water vapor nozzle 14 injects the water vapor 51, the water vapor 51 hits the support body 41. Unlike the water flow 31 injected from the water flow nozzle 12, most of the water vapor 51 is returned to the support 41. As a result, the fibers of the web 30 are rolled up and loosened. Further, the fibers of the web 30 are separated by the water vapor 51 to form the first grooves 4, and the separated fibers move and gather in the width direction side of the portion 53 where the water vapor 51 corresponds to the support body 41. The ridge 3 is formed.

  Since the strength of the web 30 is enhanced by the high-pressure water flow, it is not necessary to provide a net on the web 30 for preventing the web 30 from being blown off by the water vapor 51 when the water vapor 51 is jetted onto the web 30. Therefore, the processing efficiency of the web 30 by the water vapor 51 is increased. Moreover, since it is not necessary to provide the said net | network, the maintenance of the nonwoven fabric manufacturing apparatus 10 and the manufacturing cost of a nonwoven fabric can be held down.

  The water vapor sprayed from the water vapor nozzle 14 is high-pressure water vapor. The pressure of water vapor ejected from the water vapor nozzle 14 is preferably 0.3 to 1.5 MPa. If the water vapor pressure is less than 0.3 MPa, a sufficiently high first soot may not be formed. In addition, when the vapor pressure of the high-pressure steam is higher than 1.5 MPa, the web 30 may be perforated, the web 30 may be broken, or blown off.

  The suction force by which the support sucks the web by the suction box 13 that sucks the water vapor jetted from the water vapor nozzle 14 is preferably −1 to −12 kPa. If the suction force of the support is less than −1 kPa, there may be a problem that it is dangerous because water vapor cannot be sucked up and blown up. Further, if the suction force of the support is larger than −12 kPa, there may be a problem that the fibers fall into the suction.

  The distance between the tip of the water vapor nozzle 14 and the upper surface of the web 30 is preferably 1.0 to 10 mm. If the distance between the tip of the water vapor nozzle 14 and the upper surface of the web 30 is smaller than 1.0 mm, there may be a problem that the web 30 is perforated, the web 30 is torn or blown away. Further, if the distance between the tip of the water vapor nozzle 14 and the upper surface of the web 30 is greater than 10 mm, the force for forming grooves on the surface of the web 30 in the high-pressure steam is dispersed, and the surface of the web 30 is dispersed. The efficiency of forming grooves is reduced.

The hole diameter of the water vapor nozzle 14 is preferably larger than the hole diameter of the water flow nozzle 12, and the hole pitch of the water vapor nozzle 14 is larger than the hole pitch of the water flow nozzle 12. As a result, as shown in FIG. 1, the high pressure water vapor injected from the water vapor nozzle 14 causes the web 30 to remain on the web 30 while leaving the second soot and the second groove formed by the high pressure water flow injected from the water flow nozzle 12. A first ridge and a first groove can be formed. Of the webs 30, the region R ₂ where the second ridges and the second grooves formed by high-pressure water jet there is a plurality, a region apparent density of the web 30 is large, the first and the first ridge by high-pressure steam The region R ₁ where the grooves are formed is a region where the apparent density of the web 30 is reduced by high-pressure steam.

  The pore diameter of the water vapor nozzle 14 is preferably 150 to 600 μm. If the hole diameter of the water vapor nozzle 14 is too small, there may be a problem that energy is insufficient and the fibers cannot be scraped sufficiently. Moreover, when the hole diameter of the water vapor nozzle 14 is too large, the problem that the energy is too large and the base material damage becomes too large may occur.

  It is preferable that the hole pitch (distance between the centers of adjacent holes) of the water vapor nozzle 14 is 3.0 to 8.0 mm. If the hole pitch of the water vapor nozzle 14 is too small, the second ridge and the second groove will disappear. On the other hand, if the hole pitch of the water vapor nozzles 14 is too large, the number of flutes will decrease, and the scraping ability of dirt will deteriorate, and it will be difficult to maintain bulkiness.

  The high pressure steam forms a first ridge and a first groove on the upper surface of the web 30, and a lower surface of the web 30 (a surface on the support 41 side of the web 30) corresponding to the pattern of the support 41 (not shown). Irregularities may be formed. In addition, the groove | channel by the high pressure water flow may be formed also in the lower surface of the web, or the groove by the high pressure steam may be formed.

  Thereafter, as shown in FIG. 3, the web 30 is transferred to the web transport conveyor 18 by the suction pickup 17. The web 30 is further transferred to the web conveyor 19 and then transferred to the drying drum 20. The drying drum 20 is, for example, a Yankee dryer, and attaches the web 30 to a drum heated to about 160 ° C. with water vapor to dry the web 30. And the dried web 30 is wound up by the winder 22 as a nonwoven fabric.

If aspects of the nonwoven fabric shown in Figure 1, hole pitches of water nozzles 12, coincides with the spacing d ₆ of the second groove of two adjacent, the hole pitch of the steam nozzle 14, two adjacent first matching distance d ₄ of one groove.
The nonwoven fabric of the aspect shown in FIG. 2 is obtained when water vapor | steam is injected to the position of the arrow described in the upper part of FIG. That is, the second ridges and the spacing of the second adjacent across the groove 2 of the first groove 4,4 and p _1, a first groove 4 adjacent to each other across the third ridge 7 a When the interval between the third groove 8 and p _2, the hole pitch of the steam nozzle 14 is a repetition of p _{1 /} p 2 _/ p _2, the pitch of the water nozzle, the distance between the two second groove adjacent d ₆ In this case, the nonwoven fabric of the embodiment shown in FIG. 2 is obtained.
When the hole pitch of the water vapor nozzle 14 consists of two kinds of intervals as shown in FIG. 2, the larger interval is preferably 3.0 to 8.0 mm, and the smaller interval is preferably 2.0. ~ 2.5 mm.

FIG. 9 is a diagram showing another example of a nonwoven fabric manufacturing apparatus for manufacturing the nonwoven fabric of the present invention.
In the nonwoven fabric manufacturing apparatus 10 shown in FIG. 9, a fine pitch ridge is formed on the upper surface (hereinafter referred to as “B surface”) of the web 30 by the high-pressure water flow from the water flow nozzle 12, and the water jet condition is adjusted. By doing so, grooves with fine pitch are formed on the opposite surface of the web 30 (hereinafter referred to as “A surface”). The web jetted with water is transferred to the web conveyor 18 by the suction pickup 17, then transferred to the web conveyor 19, and then transferred to the drying drum 20. The drying drum 20 is, for example, a Yankee dryer, and the web 30 is dried by attaching the web 30 to a drum heated by water vapor. In the nonwoven fabric manufacturing apparatus shown in FIG. 9, the moisture content of the web 30 can be adjusted before entering the water vapor injection step. The moisture content of the web 30 before entering the water vapor injection step is preferably 10 to 45%. Here, the moisture content (%) is the number of g of water contained with respect to 100 g of the total mass of the web 30 containing water. When the moisture content of the web 30 is too small, the hydrogen bonding force between the fibers of the web 30 becomes strong, and the energy required to loosen the fibers of the web 30 by water vapor described later becomes very high. On the other hand, if the moisture content of the web 30 is too large, the energy required for drying the web 30 to a predetermined moisture content or less by water vapor described later becomes very high.

  Next, the web 30 is sent to a water vapor injection process. In the water vapor injection step, the web 30 moves on the mesh-shaped outer peripheral surface of the cylindrical suction drum 15. At this time, water vapor is jetted onto the web 30 from the water vapor nozzle 14 disposed above the outer peripheral surface of the suction drum 15. Although two rows of water vapor nozzles 14 are illustrated in FIG. 9, there may be one row or three or more rows. In the case of the nonwoven fabric manufacturing apparatus of FIG. 9, the surface of the web on which the water vapor is injected is the surface (A surface) opposite to the surface on which the water flow is injected. The suction drum 15 has a built-in suction device, and the water vapor ejected from the water vapor nozzle 14 is sucked by the suction device. The first ridge 3 and the first groove 4 are formed on the A surface of the web 30 by the steam sprayed from the steam nozzle 14.

  An example of the water vapor nozzle 14 disposed above the suction drum 13 is shown in FIG. FIG. 10 shows an example in which the water vapor nozzles 14 are in one row. The water vapor nozzle 14 blows a plurality of water vapors 51 arranged in the width direction (CD) of the web 30 toward the web 30. As a result, on the A surface of the web 30, a plurality of grooves 52 that are aligned in the width direction of the web 30 and extend in the machine direction (MD) are formed. The groove 52 corresponds to the first groove 4.

  The steam sprayed web is transferred to the drying drum 21 as shown in FIG. The drying drum 21 is also a Yankee dryer, for example, and attaches the web 30 to the drum heated by water vapor to dry the web 30. The web 30 after passing through the drying drum 21 needs to be sufficiently dried. Specifically, the moisture content of the web 30 after passing through the drying drum 21 is preferably 5% or less. . The dried web 30 is wound around the winder 22 as a nonwoven fabric.

The high-pressure hydroentanglement process entangles the fibers and tightens the web (densification) to increase the strength of the web. High pressure steam treatment unravels the fibers (decreases density) and makes the web bulky. At this time, since the amount of energy is higher in the high-pressure water flow treatment, only a part of the web is unraveled in the high-pressure steam treatment, and the fiber can be shaped without being broken.
According to the present invention, by performing high-pressure steam spraying treatment on a part of the hydroentangled nonwoven fabric to form an uneven structure with different sheet bulk, capillarity occurs in a bulky (small specific volume) part during liquid impregnation. The liquid concentrates. When viewed in cross-section, there are a lot of liquid and a small area in succession, so there is an area for draining liquid and an area for sucking liquid when wiping, resulting in a sheet with good dirt removal and little moisture remaining. be able to.

  The nonwoven fabric of this invention is used in order to produce a wet tissue. The wet tissue can be produced by applying a liquid to the nonwoven fabric. The amount of the liquid is, for example, about 3 times the dry mass of the nonwoven fabric. The liquid is typically distilled water, but other examples include mixed solutions of preservatives such as propylene glycol and paraben.

Example 1
The nonwoven fabric manufacturing apparatus 10 shown in FIG. 9 was used to manufacture a nonwoven fabric as follows.
70% by mass of softwood bleached kraft pulp (NBKP) (Canadian Freeness Standard (cfs) 700cc), a fineness of 1.1 dtex and a fiber length of 7 mm (corona manufactured by Daiwabo Rayon Co., Ltd.) 30% by mass The nonwoven fabric raw material containing was prepared. The raw material supply head 11 was used to supply a nonwoven fabric raw material onto a support for a web forming conveyor (OS 80 manufactured by Nippon Filcon Co., Ltd.), and a web was formed by dehydrating the nonwoven fabric raw material using a suction box. The basis weight (dry basis) of the web was 50 g / m ² .
Thereafter, a high pressure water stream was jetted onto the web using two high pressure water nozzles. At this time, the high-pressure water energy of each high-pressure water nozzle is 0.142 kW / m ² , and the high-pressure water flow is jetted onto the web using the two high-pressure water nozzles. The high pressure water flow energy was 0.284 kW / m ² . The hole diameter of the high-pressure water flow nozzle was 92 μm, the hole pitch was 0.5 mm, and the web traveling speed was 70 m / min. By the water jetting, a grooved structure with a pitch of 0.5 mm was formed on the water jetting surface of the web, and a grooved structure with a pitch of 0.5 mm was formed on the surface opposite to the water jetting surface.
The water jetted web was sent to the water vapor jet process through two web transfer conveyors and a Yankee dryer.
In the steam spraying process, high-pressure steam was sprayed on the surface opposite to the water spray surface of the web using two steam nozzles. The pressure of the high-pressure steam at this time is 0.7 MPa, the temperature of the high-pressure steam is about 175 ° C., the distance between the tip of the steam nozzle and the top surface of the web is 2.0 mm, and the pore diameter of the steam nozzle is The hole pitch was 4.0 mm, and the web traveling speed was 70 m / min.
Thereafter, the web was passed through a Yankee dryer, sent to a winder, and wound as a nonwoven fabric.

A photograph (wet state) of the water jet surface of the web after jetting the water flow is shown in FIG.
FIG. 12 shows a photograph (wet state) of the water vapor jet surface of the web after the water vapor is jetted.
A photograph of the water vapor jet surface of the obtained nonwoven fabric (dry state) is shown in FIG.

About the obtained nonwoven fabric, non-woven fabric basis weight, first ridge height h ₃ (when dried), second ridge height h ₅ (when dried), apparent density of region R ₁ , apparent density of region R ₂ , Dry tensile strength, dry tensile elongation, wet tensile strength and wet tensile elongation were measured. The measurement results are shown in Table 1.
Moreover, the obtained nonwoven fabric was impregnated with distilled water having a mass three times the dry mass of the nonwoven fabric to prepare a wet tissue. Using the prepared wet tissue, an artificial dirt wiping property test was performed, and the dirt removal rate was measured on the high-pressure steam jet surface. The measurement results are shown in Table 1.

Example 2
A nonwoven fabric was produced under the same conditions as in Example 1 except that the water vapor nozzle pitch was changed to 3 mm. The obtained nonwoven fabric was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

Comparative Example 1
A non-woven fabric was produced under the same conditions as in Example 1 except that steam injection was not performed. The obtained nonwoven fabric was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

Comparative Example 2
A nonwoven fabric was produced under the same conditions as in Example 1 except that the water vapor nozzle pitch was changed to 2 mm. The wrinkle groove formed on the A surface by water jet is extinguished by the water vapor injection, and the A surface of the obtained nonwoven fabric has only the first wrinkles and the first groove formed by the water vapor injection, The second ridge and the second groove formed by the water jet were not present. The obtained nonwoven fabric was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 3
A nonwoven fabric was produced under the same conditions as in Example 1 except that the steam nozzle pitch was changed to 5 mm / 2 mm / 5 mm / 2 mm. FIG. 14 shows a photograph of the water vapor spray surface of the nonwoven fabric obtained (taken in a state of being wound into a roll). The obtained nonwoven fabric was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

Incidentally, the web moisture content before steam injection, after steam injection web moisture content, the winding time of the web moisture content, nonwoven basis weight, dry thickness _(dry) the height h ₃ of the first ridge, the height of the second ridges h ₅ (during drying), apparent density in region R ₁ , apparent density in region R ₂ , dry tensile strength, dry tensile elongation, wet tensile strength, wet tensile elongation, and soil removal rate were measured as follows. did.

[Web moisture content before steam injection]
The web dried on the drying drum 20 was sampled to a size of 30 cm × 30 cm, the outlet mass (W ₁ ) of the drying drum 20 was measured, and then the sample piece was left in a thermostatic bath at 105 ° C. for 1 hour to be completely dried. After that, the mass (D ₁ ) is measured. The moisture content (%) of the web before steam spraying is calculated by the following formula. In addition, the web moisture content before water vapor | steam injection is an average value of ten measured values.
Web moisture content before water vapor injection (%) = (W ₁ −D ₁ ) / W ₁ × 100

[Web moisture content after steam injection]
A web in which high-pressure steam is jetted onto the web from the steam nozzle 14 on one suction drum 15 is sampled to a size of 30 cm × 30 cm, and the mass (W ₂ ) after passing through the steam nozzle 14 is measured. After standing for 1 hour in a constant temperature bath and drying completely, the mass (D ₂ ) is measured. The web moisture content (%) after steam injection is calculated by the following equation. In addition, the web moisture content after water vapor | steam injection is an average value of ten measured values.
Water content after web injection (%) = (W ₂ −D ₂ ) / W ₂ × 100

[Web moisture content during winding]
The wound web is sampled to a size of 30 cm × 30 cm, the mass (W ₃ ) after winding is measured, and then the sample piece is left in a constant temperature bath at 105 ° C. for 1 hour to completely dry and then the mass ( D ₃₎ to measure. The web moisture content (%) during winding is calculated by the following formula. In addition, the web moisture content at the time of winding is an average value of the measured value in N = 10.
Winding web moisture content (%) = (W ₃ −D ₃ ) / W ₃ × 100

[Nonwoven fabric basis weight]
The nonwoven fabric basis weight was calculated by dividing the absolutely dry sample mass D ₃ (g) when the web moisture content during winding was measured by the area (0.09 m ² ). The nonwoven fabric basis weight is an average value of 10 measured values.

[First ridge height h ₃ (when dried) and second ridge height h ₅ (when dried)]
A non-woven fabric (dried product) sample was impregnated with liquid nitrogen and frozen, then cut with a razor, returned to room temperature, and then photographed at a magnification of 50 using an electron microscope (for example, KEYENCE VE7800). Were measured, and the height h ₃ of the first ridge (when dried) and the height h ₅ of the second ridge (when dried) were measured. The reason for freezing the sample is to prevent the thickness from fluctuating due to compression during cutting with a razor.

[Apparent density of regions R ₁ and R ₂ ]
The cross section of the microscope such as a nonwoven fabric, enlarged photographing more than 50 times, to measure the number of fibers per unit area of thickness × width 0.5mm region R ₁ or R _2, and calculates the fiber weight than its result The apparent density was calculated.

The apparent density difference is calculated by the following formula.
Apparent density difference (%) = (ρ ₂ −ρ ₁ ) / ρ ₁ × 100
However, [rho ₁ is the apparent density of the region _{R 1, ρ 2} is the apparent density of the region _{R 2.}

[Dry tensile strength]
From the manufactured nonwoven fabric, a strip-shaped test piece with a width of 25 mm whose longitudinal direction is the machine direction of the web and a strip-shaped test piece with a width of 25 mm whose longitudinal direction is the width direction of the web are cut out, and a measurement sample is obtained. Produced. Samples for measurement in the machine direction and width direction were each measured using a tensile tester (autograph model AGS-1kNG manufactured by Shimadzu Corp.) equipped with a load cell having a maximum load capacity of 50 N. The tensile strength was measured under the conditions of a distance between grips of 100 mm and a tensile speed of 100 mm / min. The average value of the tensile strength of each of the three measurement samples of the measurement sample in the machine direction and the width direction was defined as the dry tensile strength in the machine direction and the width direction.

[Dry tensile elongation]
From the manufactured nonwoven fabric, a strip-shaped test piece with a width of 25 mm whose longitudinal direction is the machine direction of the web and a strip-shaped test piece with a width of 25 mm whose longitudinal direction is the width direction of the web are cut out, and a measurement sample is obtained. Produced. Samples for measurement in the machine direction and width direction were each measured using a tensile tester (autograph model AGS-1kNG manufactured by Shimadzu Corp.) equipped with a load cell having a maximum load capacity of 50 N. The tensile elongation was measured under the conditions of a distance between grips of 100 mm and a tensile speed of 100 mm / min. Here, the tensile elongation is a value obtained by dividing the maximum elongation (mm) when the measurement sample is pulled by a tensile tester by the distance between grips (100 mm). The average value of the tensile elongation of each of the three measurement samples of the measurement sample in the machine direction and the width direction was defined as the dry tensile elongation in the machine direction and the width direction.

[Wet tensile strength]
A 25 mm wide strip-shaped test piece whose longitudinal direction is the web machine direction and a 25 mm wide strip-shaped test piece whose longitudinal direction is the web width direction are cut out from the manufactured nonwoven fabric to prepare a measurement sample. Then, the measurement sample was impregnated with 2.5 times as much water as the measurement sample (water content: 250%). The measurement samples in the machine direction and the width direction were each measured using a tensile tester (autograph model AGS-1kNG manufactured by Shimadzu Corporation) equipped with a load cell having a maximum load capacity of 50 N. The tensile strength of the sample for measurement was measured under the conditions of a distance between grips of 100 mm and a tensile speed of 100 mm / min. The average value of the tensile strength of each of the three measurement samples of the measurement sample in the machine direction and the width direction was defined as the wet tensile strength in the machine direction and the width direction.

[Wet tensile elongation]
A 25 mm wide strip-shaped test piece whose longitudinal direction is the web machine direction and a 25 mm wide strip-shaped test piece whose longitudinal direction is the web width direction are cut out from the manufactured nonwoven fabric to prepare a measurement sample. Then, the measurement sample was impregnated with 2.5 times as much water as the measurement sample (water content: 250%). The measurement samples in the machine direction and the width direction were each measured using a tensile tester (autograph model AGS-1kNG manufactured by Shimadzu Corporation) equipped with a load cell having a maximum load capacity of 50 N. The tensile elongation of the sample for use was measured under the conditions of a distance between grips of 100 mm and a tensile speed of 100 mm / min. The average value of the tensile elongation of each of the three measurement samples of the measurement sample in the machine direction and the width direction was defined as the wet tensile elongation in the machine direction and the width direction.

[Dirt removal rate]
As a simulated soil, a paste having a blending ratio of 12.6% by mass of carbon black, 20.8% by mass of beef tallow extremely hardened oil, and 66.6% of liquid paraffin is prepared. The paste and hexane are mixed at a ratio of 85:15 (mass ratio). 0.05 mL of hexane diluted paste is dropped on a glass plate. After drying for 24 hours in a high temperature and high humidity chamber (20 ° C., humidity 60%), the color is scanned with a scanner. A wiping test (once) is performed with a friction coefficient measuring device of Tester Sangyo Co., Ltd. under conditions of 150 mm / min and a load of 60 g. After the test, the change in color is scanned with a scanner, and the change rate of the color of 16.9 mm × 16.9 mm in the scanned area is calculated by the following formula to obtain the stain removal rate.
Dirt removal rate (%) = (C ₀ −C ₁ ) / C ₀ × 100
However, C ₀ is the color of the pre-wiping, C ₁ is the color after wiping.
It can be judged that the larger the color removal rate, the more dirt can be removed. Measured with N number = 3, and the average value of 3 times is defined as the stain removal rate.

  The nonwoven fabric of this invention can be used conveniently in order to produce a wet tissue.

DESCRIPTION OF SYMBOLS 1 Nonwoven fabric 3 First ridge 4 First groove 5 Second ridge 6 Second groove 10 Nonwoven fabric manufacturing apparatus 11 Raw material supply head 12 Water nozzle 13 Suction box 14 Steam nozzle 15 Suction drum 16 Web forming conveyor 17 Suction pickup 18 , 19 Web conveying conveyor 20, 21 Drying drum 22 Winder 30 Web 31 High-pressure water flow 32 Groove 41 Support body 51 High-pressure steam 52 Groove

Claims (16)

A nonwoven fabric for wet tissue containing absorbent fibers,
A plurality of first ridges, first grooves, second ridges and second grooves extending in the same direction are formed on at least one surface of the nonwoven fabric,
The height of the top of the first ridge is higher than the height of the top of the second ridge,
The height of the top of the second ridge is higher than the height of the bottom of the second groove,
The height of the bottom of the second groove is higher than the height of the bottom of the first groove,
A first groove is located between two adjacent first ridges;
A plurality of second ridges and second grooves are located between two adjacent first ridges where the first groove is not located,
A non-woven fabric characterized in that an interval between two first ridges adjacent to each other across the first groove is wider than an interval between two second ridges adjacent to each other across the second groove.   The apparent density in the dry state of the nonwoven fabric in the region where the first wrinkles and the first grooves are located is smaller than the apparent density in the dry state of the region where the second wrinkles and the second grooves are located Item 10. The nonwoven fabric according to item 1.   The nonwoven fabric according to claim 1 or 2, wherein the difference between the height of the top of the first ridge and the height of the top of the second ridge is 0.1 mm or more.   Absorbent fiber contains a cellulose, The nonwoven fabric of any one of Claims 1-3 characterized by the above-mentioned.   The nonwoven fabric according to any one of claims 1 to 4, wherein the liquid holding portion and the non-holding portion can be visually confirmed at the time of liquid impregnation.   The nonwoven fabric according to any one of claims 1 to 5, wherein 30% or more of the fibers constituting the nonwoven fabric are absorbent fibers. The apparent density in the dry state of the nonwoven fabric in the region where the first ridge and the first groove are located is 0.030 to 0.10 g / cm ³ , and the nonwoven fabric in the region where the second ridge and the second groove are located The non-woven fabric according to any one of claims 1 to 6, wherein an apparent density in a dry state is 0.12 to 0.20 g / cm ³ .   The non-woven fabric according to any one of claims 1 to 7, wherein a distance between two first wrinkles adjacent to each other with the second wrinkle and the second groove interposed therebetween is 3 mm or more.   The fiber length of the fiber which comprises a nonwoven fabric is 20 mm or less, The nonwoven fabric of any one of Claims 1-8 characterized by the above-mentioned.   The non-woven fabric according to any one of claims 1 to 9, wherein the difference between the height of the top of the second ridge and the height of the bottom of the second groove is 0.05 to 0.10 mm.   11. The nonwoven fabric according to claim 1, wherein an interval between two second ridges adjacent to each other with the second groove interposed therebetween is 0.3 to 1.0 mm.   The difference between the height of the top of the first ridge and the height of the bottom of the first groove is 0.15 to 0.60 mm, The nonwoven fabric according to any one of claims 1 to 11.   A third ridge is formed between the second ridge and two adjacent first ridges where the second groove is not located, and the height of the top of the third ridge is the top of the second ridge. The nonwoven fabric according to any one of claims 1 to 12, wherein the nonwoven fabric is higher than the height.   The first ridge and the first groove are formed by jetting water vapor, and the second ridge and the second groove are formed by jetting water flow. The nonwoven fabric of any one of Claims 1-13. A method for producing the nonwoven fabric for wet tissue according to claim 1,
Supplying a mixture of fibers containing absorbent fibers and water onto a support to form a water-containing web on the support;
A step of injecting a water flow onto the web from water flow nozzles arranged at equal intervals in the width direction of the web to entangle the fibers;
A method comprising a step of spraying water vapor onto a web from which water flow has been jetted from a water vapor nozzle arranged side by side in the width direction of the web at intervals wider than the interval between the water flow nozzles, and a step of drying the web from which water vapor has been jetted.   A wet tissue obtained by impregnating the nonwoven fabric according to any one of claims 1 to 14 with a liquid.