JP5211033B2 - Nonwoven manufacturing method - Google Patents

Description

  The present invention relates to a method for producing a nonwoven fabric. The nonwoven fabric produced in accordance with the present invention is particularly suitably used as a constituent material for various absorbent articles such as sanitary napkins and disposable diapers.

  Regarding a nonwoven fabric made from a heat-extensible fiber, which is a fiber whose length is increased by heating, the applicant previously has a number of pressure-bonded portions to which constituent fibers are pressure-bonded or bonded, and other than pressure-bonded portions. The three-dimensional structure in which the intersections of the constituent fibers are joined by means other than pressure bonding, and the pressure bonding portion is a concave portion and the concave portion is a convex portion between at least one surface. A shaped nonwoven fabric was proposed (see Patent Document 1). This nonwoven fabric has the advantage that it has a three-dimensional uneven shape, is flexible, and has a low basis weight, without using a special manufacturing method, by using heat-extensible fibers as a raw material.

  The three-dimensionally shaped non-woven fabric is formed by embossing a web containing a heat-extensible fiber to form the pressure-bonded portion, and then performing an air-through process using hot air to extend the heat-extensible fiber and the heat-extensible fiber. Manufactured by joining the intersections of fibers by thermal fusion. As a result of repeated studies by the present inventors on such heat-extensible fibers, it has been found that the heat-extensible fibers have a lower flexural modulus than that of ordinary heat-fusible fibers. Therefore, in the above-described manufacturing method, if strong embossing is performed or hot air is blown strongly, the volume of the nonwoven fabric is reduced, and a sufficient three-dimensional effect may not be imparted to the nonwoven fabric. In order to avoid such an inconvenience, it may be possible to weaken the embossing, but in that case, the fibers are not sufficiently fixed, and the conveyance of the web in the production line becomes unstable or fuzzy. May be more likely to occur. If the hot air is blown weakly, the heat applied to the web becomes non-uniform, and the fiber elongation may become non-uniform. If the fiber elongation becomes non-uniform, one surface of the nonwoven fabric is flat and the other surface tends to be uneven, making it difficult to obtain a nonwoven fabric with a uniform structure when viewed in the thickness direction.

JP 2005-350836 A

  The present invention provides a method capable of producing a nonwoven fabric using heat-extensible fibers as a raw material and having various performances improved as compared with the above-described prior art.

In the present invention, hot air is blown in an air-through manner to a web containing a high-melting component and a low-melting component having a lower melting point, and the length of the web is increased by heating. Fusing the intersections to form a bonded web in which the constituent fibers are bonded,
It is a method of embossing a bonded web with an embossing device comprising an embossing roll having irregularities on the peripheral surface and a flat roll having a smooth peripheral surface, and producing a nonwoven fabric having irregularities on the surface,
The temperature of the hot air blown to the web is set to be equal to or higher than the melting point of the low melting point component and lower than the melting point of the high melting point component,
In the embossing process, the hot air blowing surface of the bonded web is brought into contact with the embossing roll, and the surface opposite to the hot air blowing surface is brought into contact with the flat roll.
Embossing is performed with an embossing roll set at a melting point of −20 ° C. or more of the low melting point component and a melting point of + 20 ° C. or less and a flat roll set at a normal temperature or more and a melting point of the low melting point component of + 20 ° C. or less. The manufacturing method of a nonwoven fabric is provided.

The present invention also includes a high-melting-point component and a low-melting-point component having a low melting point, and hot air is blown by an air-through method onto a web containing a heat-extensible fiber whose length is increased by heating. By fusing the intersections of the fibers to form a bonded web in which the constituent fibers are bonded,
It is a method of embossing a bonded web with an embossing device comprising an embossing roll having irregularities on the peripheral surface and a flat roll having a smooth peripheral surface, and producing a nonwoven fabric having irregularities on the surface,
The temperature of the hot air blown to the web is set to be equal to or higher than the melting point of the low melting point component and lower than the melting point of the high melting point component,
In the embossing process, the hot air blowing surface in the combined web is brought into contact with the flat roll, and the surface opposite to the hot air blowing surface is brought into contact with the embossing roll,
Embossing is performed with an embossing roll set at a melting point of −20 ° C. or more of the low melting point component and a melting point of + 20 ° C. or less and a flat roll set at a normal temperature or more and a melting point of the low melting point component of + 20 ° C. or less. The manufacturing method of a nonwoven fabric is provided.

Furthermore, the present invention provides a web containing a high-melting-point component and a low-melting-point component having a lower melting point, and a hot-extensible fiber whose length is extended by heating. By fusing the intersections of the fibers to form a bonded web in which the constituent fibers are bonded,
A pair of embossing rolls having irregularities on the peripheral surface, and the embossing device provided with an embossing roll in which the irregularities are arranged so that the convexities in each embossing roll come into contact with each other, It is a method of embossing with a chip method to produce a nonwoven fabric having irregularities on the surface,
The temperature of the hot air blown to the web is set to be equal to or higher than the melting point of the low melting point component and lower than the melting point of the high melting point component,
The present invention provides a method for producing a nonwoven fabric in which embossing is performed with each embossing roll set to a melting point of −20 ° C. or higher and a melting point of + 20 ° C. or lower.

  According to the production method of the present invention, it is possible to obtain a non-woven fabric that is suppressed in fuzz, has a good texture, and is gentle to the skin. Moreover, according to the manufacturing method of this invention, a bulky nonwoven fabric is obtained with a substantially uniform uneven structure in the thickness direction. Moreover, according to this invention, such a nonwoven fabric can be manufactured with sufficient productivity.

Fig.1 (a) is a perspective view of an example of the nonwoven fabric manufactured according to the method of this invention, FIG.1 (b) is a principal part enlarged view of the longitudinal cross-section of the nonwoven fabric shown to Fig.1 (a). FIG. 2 is a schematic view showing a nonwoven fabric manufacturing apparatus suitably used in the first embodiment of the present invention. FIG. 3 is a schematic view showing a nonwoven fabric manufacturing apparatus suitably used in the second embodiment of the present invention. FIG. 4 is a schematic view showing a nonwoven fabric manufacturing apparatus suitably used in the third embodiment of the present invention.

  The present invention will be described below based on preferred embodiments with reference to the drawings. First, the first embodiment will be described. FIG. 1A shows a perspective view of an example of a nonwoven fabric manufactured according to the manufacturing method of the present embodiment. Moreover, the principal part enlarged view of the longitudinal cross-section of the nonwoven fabric 10 shown to Fig.1 (a) is shown by FIG.1 (b). The nonwoven fabric 10 shown in FIG. 1 has a single layer structure. Each surface of the nonwoven fabric 10 has a concavo-convex shape having a large number of convex portions 19 and concave portions 18. That is, it is three-dimensionally shaped. The convex portion 19 on the one surface 10 ′ side of the nonwoven fabric 10 and the convex portion 19 on the other surface 10 ″ side are in the same position on the front and back. The same applies to the concave portion 18, and one surface 10 ′ of the nonwoven fabric 10 is the same. The recess 18 on the side and the recess 18 on the other surface 10 "side are in the same position on the front and back.

  As shown in FIG. 1B, the convex portion on the one surface 10 ′ side and the convex portion on the other surface 10 ″ side of the nonwoven fabric 10 are subject to the center point R in the thickness direction of the concave portion as the center line. The thickness is preferably h1 from the center line passing through the center point R in the thickness direction of the concave portion of the nonwoven fabric 10 to the top portion P of the convex portion on the one surface 10 ′ side, and the other surface 10 The thickness ratio h1 / h2 can be used as an index indicating the uniformity of the concavo-convex structure when the thickness up to the top Q of the convex portion on the side is h2. The closer the thickness ratio is to 1, the more uniform the uneven structure, that is, there is no substantial difference between the unevenness on the front and back sides. From the viewpoint of appearance and feel from both sides, the thickness ratio is preferably 0.5 to 2.0, particularly 0.7 to 1.4. The thickness is measured by observing the longitudinal section of the nonwoven fabric 10. First, the nonwoven fabric 10 is cut into a size of 100 mm × 100 mm, and a measurement piece is collected. A plate of 12.5 g (diameter 56.4 mm) is placed on the measurement piece, and the thickness of the nonwoven fabric under a 49 Pa pressure is measured with a microscope (VHX-900, manufactured by Keyence Corporation).

  The concave portion 18 includes a joint portion formed by compacting and joining the constituent fibers of the nonwoven fabric 10. Examples of means for forming the joint include embossing with or without heat, ultrasonic embossing, and the like. On the other hand, the convex part 19 is a non-joining part. The thickness of the concave portion 18 is smaller than the thickness of the convex portion 19. The inside of the convex portion 19 is filled with the constituent fibers of the nonwoven fabric 10. In the convex part 19, the constituent fibers of the nonwoven fabric 10 are fused at their intersections. Since the intersections of the fibers are heat-sealed in the convex portion 19, fuzz on the surface of the nonwoven fabric 10 is less likely to occur. Whether or not the fibers are thermally fused is determined by observing the nonwoven fabric 10 with a scanning electron microscope.

  The recessed part 18 has the 1st linear part 18a extended in one direction in parallel with each other. Moreover, the recessed part 18 has the 2nd linear part 18b extended in one direction in parallel so that it may cross | intersect a 1st linear part. A closed rhombus is formed by intersecting the two linear portions 18a and 18b. This rhombus portion is a convex portion 19. That is, the convex portion 19 is formed to be surrounded by a continuous closed concave portion 18. What is necessary is just to select suitably the width | variety of the recessed part 18 which consists of a linear part according to the specific use of the nonwoven fabric 10. FIG. When using the nonwoven fabric 10 as a structural member (surface sheet etc.) of an absorbent article, for example, it is preferable that the width | variety of the recessed part 18 shall be 0.1-3 mm, especially 0.5-1 mm.

  The area ratio between the concave portion 18 and the convex portion 19 in the nonwoven fabric 10 is expressed by an embossing rate (an embossed area ratio, that is, a ratio of the total area of the concave portion 18 to the entire nonwoven fabric 10), and affects the bulkiness and strength of the nonwoven fabric 10. give. From these viewpoints, the embossing rate in the nonwoven fabric 10 is preferably 5 to 35%, particularly preferably 10 to 25%. The above embossing rate is measured by the following method. First, an enlarged photograph of the surface of the nonwoven fabric 10 is obtained using a microscope (manufactured by Keyence Corporation, VHX-900), the scale is aligned with the enlarged photograph of the nonwoven fabric surface, and the dimension of the recess 18 (that is, the embossed portion) is measured. The total area P of the recesses 18 in the entire area Q of the measurement site is calculated. The embossing rate can be calculated by the formula (P / Q) × 100.

  The nonwoven fabric 10 includes, as its constituent fibers, heat-extensible fibers that are fibers whose length is increased by heating. Examples of the heat-extensible fibers include fibers that are elongated by changing the crystalline state of the resin by heating. As this heat-extensible fiber, a composite fiber containing a low melting point component and a high melting point component is used. The heat-extensible fiber is present in the nonwoven fabric 10 in a state where its length is extended by heating or in a state where it can be extended by heating. Moreover, the fiber in a state stretched by heating can be further stretched by further heating. This can be confirmed by a method of taking out fibers from the nonwoven fabric 10 and measuring thermal extensibility as described later. Details of the heat-extensible fibers will be described later.

  The heat-extensible fiber made of the above-mentioned composite fiber comprises a high-melting point component made of a high-melting point resin and a low-melting point component made of a low-melting point resin having a melting point or softening point lower than the melting point of the high-melting point component. The component is present continuously in the length direction on at least a part of the fiber surface. The high melting point component in the heat extensible fiber is a component that expresses the heat extensibility of the fiber, and the low melting point component is a component that expresses the heat fusibility.

  The heat stretchable fiber is stretchable by heat at a temperature lower than the melting point of the high melting point component. The heat-extensible conjugate fiber has a thermal elongation rate of 0.5 to 20% at a temperature 10 ° C. higher than the melting point of the low-melting point component, and 10 ° C. higher than the softening point in the case of a resin having no melting point, especially 3 It is preferably -20%, especially 5-20%. The nonwoven fabric 10 containing fibers having such an elongation rate becomes bulky due to the elongation of the fibers, or has a three-dimensional appearance. For example, the uneven shape on the surface of the nonwoven fabric 10 becomes remarkable.

  The melting points of the high melting point component and the low melting point component are measured using a differential scanning calorimeter (DSC6200 manufactured by Seiko Instruments Inc.). A finely cut fiber sample (sample weight 2 mg) is subjected to thermal analysis at a heating rate of 10 ° C./min, and the melting peak temperature of each resin is measured. The melting point is defined by its melting peak temperature. If the melting point of the low melting point component cannot be clearly measured by this method, this resin is defined as “resin having no melting point”. In this case, the softening point is the temperature at which the low melting point component is fused to such an extent that the strength of the fusion point of the fiber can be measured.

[Measurement method of thermal elongation of fiber]
The thermal elongation rate of the fiber is measured by the following method. A thermomechanical analyzer TMA / SS6000 manufactured by Seiko Instruments Inc. is used. As a sample, after preparing a plurality of fibers having a fiber length of 10 mm or more so that the total weight per 10 mm of the fiber length is 0.5 mg, and arranging the plurality of fibers in parallel, Mount on the device with 10mm distance between chucks. The measurement start temperature is 25 ° C., and the temperature is increased at a temperature increase rate of 5 ° C./min with a constant load of 0.73 mN / dtex applied. The amount of elongation of the fiber at that time is measured, and in the case of a resin having no melting point at a temperature 10 ° C. higher than the melting point of the low melting point component, the elongation Cmm at a temperature 10 ° C. higher than the softening point is read. The thermal elongation rate of the fiber is calculated from (C / 10) × 100 [%]. The reason why the thermal elongation rate is measured at the above-mentioned temperature is, as will be described later, when the nonwoven fabric 10 is produced by thermally fusing the intersections of the fibers, and is higher than the melting point or softening point of the low melting point component. It is because it is normal to manufacture in the range up to about 10 degreeC high temperature.

[Evaluation of thermal extensibility of fibers taken out from non-woven fabric]
When taking out fiber from a nonwoven fabric and judging the heat | fever extensibility of a fiber, the following methods are used. First, five fibers located at each part of the nonwoven fabric shown in FIG. The length of the fiber to be collected is 1 mm or more and 5 mm or less. The collected fiber is sandwiched between preparations, and the total length of the sandwiched fiber is measured. For measurement, a microscope VHX-900 and a lens VH-Z20R manufactured by KEYENCE were used. The measurement was performed by observing the fiber at a magnification of 50 to 100 times and using a measurement tool incorporated in the apparatus for the observed image. The length obtained by the measurement is defined as “the total length of fibers collected from the nonwoven fabric” Y. The fiber whose total length has been measured is placed in a DSC6200 sample container (product name: robot container 52-023P, 15 μL, aluminum) manufactured by SII Nano Technology. The container containing the fibers is placed in a sample place in a DSC 6200 heating furnace set in advance at a temperature 10 ° C. lower than the melting point of the high melting point component. 60 seconds after the temperature (display name in the measurement software: sample temperature) measured by a thermocouple installed directly under the DSC6200 sample storage area is within a range of ± 1 ° C that is 10 ° C lower than the melting point of the high melting point component Heat and then quickly remove. The heat-treated fiber is taken out from the DSC sample container and sandwiched between preparations, and the total length of the sandwiched fiber is measured. For measurement, a microscope VHX-900 and a lens VH-Z20R manufactured by KEYENCE were used. The measurement was performed by observing the fiber at a magnification of 50 to 100 times and using a measurement tool incorporated in the apparatus for the observed image. The length obtained by the measurement is referred to as “full length of fiber after heat treatment” Z. The thermal elongation rate (%) is calculated from the following formula.
Thermal elongation (%) = (Z−Y) ÷ Y × 100 [%]
This is defined as the thermal elongation rate of the fiber taken out from the nonwoven fabric. When this thermal elongation rate is larger than 0, it can be determined that the fiber is a heat-extensible fiber.

  There is no restriction | limiting in particular in the kind of a high melting-point component and a low melting-point component, What is necessary is just a resin with fiber forming ability. In particular, when the difference between the melting points of the two resin components, or the difference between the melting point of the high melting point component and the softening point of the low melting point component is 20 ° C. or more, particularly 25 ° C. or more, it is easy to produce the nonwoven fabric 10 by thermal fusion. This is preferable because it can be performed. When the heat-extensible fiber is a core-sheath type composite fiber, a resin having a melting point of the core component higher than the melting point or softening point of the sheath component is used. In particular, it is preferable to use a core-sheath type heat-stretchable conjugate fiber having polypropylene (PP) or polyethylene terephthalate (PET) as a core and a resin having a melting point lower than these as a sheath. Preferred combinations of the high melting point component and the low melting point component include high density polyethylene (HDPE), low density polyethylene (LDPE), and linear low density polyethylene (when the high melting point component is PP). LLDPE), ethylene propylene copolymer, polystyrene and the like. When a polyester resin such as PET or polybutylene terephthalate (PBT) is used as the high melting point component, PP, copolymer polyester, etc. may be mentioned as the low melting point component in addition to the above-described examples of the low melting point component. Furthermore, examples of the high melting point component include polyamide polymers and two or more types of copolymers of the above-described high melting point component. Examples of the low melting point component include two or more types of copolymers of the low melting point component described above. Also mentioned. These are appropriately combined.

  As the fiber length of the heat-extensible fiber, an appropriate length is used according to the method for manufacturing the nonwoven fabric 10. For example, when the nonwoven fabric 10 is manufactured by a card method as described later, the fiber length is preferably about 30 to 70 mm.

  The fiber diameter of the heat-extensible fiber is appropriately selected according to the specific use of the nonwoven fabric 10. When the nonwoven fabric 10 is used as a constituent member of an absorbent article such as a surface sheet of the absorbent article, it is preferably 10 to 35 μm, particularly preferably 15 to 30 μm. In addition, the fiber diameter of the heat-extensible fiber is reduced by stretching. The fiber diameter is a fiber diameter when the nonwoven fabric 10 is actually used.

  Examples of the heat-extensible fibers include Japanese Patent No. 4131852, Japanese Patent Laid-Open No. 2005-350836, Japanese Patent Laid-Open No. 2007-303035, Japanese Patent Laid-Open No. 2007-204899, Japanese Patent Laid-Open No. 2007-204901, and Japanese Patent Laid-Open No. 2007-2007. The fiber described in 204902, Unexamined-Japanese-Patent No. 2008-101285, etc. can be used.

  The nonwoven fabric 10 includes two components having different melting points in addition to the heat-extensible fibers, and is a non-heat-extensible core-sheath-type heat-fusible composite that is stretched and does not extend in length by heating. Fibers may be included. Further, it may contain fibers that are non-thermally extensible and do not inherently have heat-fusibility (for example, natural fibers such as cotton and pulp, rayon, and acetate fibers).

  As described above, the nonwoven fabric 10 includes a heat-extensible fiber as a constituent fiber, and the heat-extensible fiber is also used as a raw material of the nonwoven fabric 10. In the following description, for the purpose of distinguishing between the heat-extensible fibers contained in the nonwoven fabric 10 and the heat-extensible fibers that are the raw material of the nonwoven fabric 10, the heat-extensible fibers that are the raw material of the nonwoven fabric 10 are referred to as “ It is called “heat-extensible raw fiber”. When simply referred to as “heat-extensible fiber”, it refers to a heat-extensible fiber contained in the nonwoven fabric 10.

  The heat-extensible raw fiber is composed of a composite fiber containing a low-melting component and a high-melting component, similarly to the heat-extensible fiber. Therefore, regarding the details of the heat-extensible raw material fiber, the explanation regarding the heat-extensible fiber described above is appropriately applied. FIG. 2 shows a suitable apparatus for producing the nonwoven fabric 10 using a heat-extensible raw fiber as a raw material. The apparatus 20 shown in the figure includes a web manufacturing unit 30, a hot air blowing unit 40, and an embossing unit 50. In the web manufacturing unit 30, the web 10 a is manufactured using a heat-extensible raw material fiber (that is, a heat-extensible fiber before being stretched) as a raw material of the nonwoven fabric 10 and other fibers as necessary. The web 10a has a first surface 101 and a second surface 102 located on the opposite side. The first surface 101 is a surface to which hot air is blown in a hot air blowing unit 40 to be described later, and a surface in contact with the embossing roll 51 in an embossing unit 50 to be described later. The second surface 102 is a surface that faces the conveyor belt 42 made of a breathable net in the hot air blowing unit 40 and a surface that contacts the flat roll 52 in the embossing unit 50.

  As the web manufacturing unit 30, for example, a card machine 31 as shown in the figure can be used. Depending on the specific application of the nonwoven fabric 10, another web manufacturing apparatus such as an airlaid apparatus can be used instead of the card machine 31. The web 10a manufactured by the card machine 31 is in a state where its constituent fibers are loosely entangled with each other, and the shape retaining property as a sheet is not obtained. In addition, no elongation has occurred in the heat-extensible raw fiber that is a constituent fiber. Therefore, in order to give the web 10a shape retention as a sheet and to cause the heat-extensible raw fiber to be thermally stretched, the web 10a is processed in the hot air blowing section 40 to form the bonded web 10b.

  The hot air blowing unit 40 includes a hood 41. The web 10a passes through the hood 41. Moreover, the hot air spraying part 40 is provided with the conveyor belt 42 which consists of a breathable net. The conveyor belt 42 circulates in the hood 41. A suction box (not shown) is installed inside the circulating conveyor belt 42. The suction box is used for sucking hot air blown to the web 10a. The web 10a is placed on the conveyor belt 42 and conveyed in the hot air blowing unit 40. The conveyor belt 42 is made of a resin such as metal or polyethylene terephthalate.

  In the hot air blowing section 40, hot air is blown against the web 10a by an air-through method. That is, the hot air blowing unit 40 is configured such that hot air heated to a predetermined temperature penetrates the web 10a. The air-through process is performed at a temperature at which the heat-extensible raw fiber in the web 10a is elongated by heating. And it is performed at a temperature at which the intersection of the heat-extensible raw fibers in the web 10a is heat-sealed. Specifically, the temperature of the hot air blown onto the web 10a is set to be equal to or higher than the melting point of the low melting point component and lower than the melting point of the high melting point component in the heat-extensible raw fiber made of composite fiber. By blowing hot air at this temperature, the elongation of the heat-extensible raw fiber is sufficiently exhibited, and the heat-extensible raw fiber is surely fused with each other, so that the bonded web 10b having high shape retention can be obtained. Specifically, if the temperature of the hot air is lower than the melting point of the low-melting component, the heat-extensible raw fiber does not sufficiently elongate, and a bulky nonwoven fabric cannot be obtained. Further, the fusion between the heat-extensible raw fibers does not occur reliably, and the transportability of the bonded web 10b is lowered. On the other hand, when the temperature of the hot air is higher than the melting point of the high melting point component, the heat-extensible raw fiber is excessively melted and the texture of the nonwoven fabric 10 is lowered. From these viewpoints, the temperature of the hot air blown to the web 10a is preferably the melting point of the low melting point component to the melting point of the low melting point component + 15 ° C., and the melting point of the low melting point component + 5 ° C. to the melting point of the low melting point component + 10 ° C. More preferably.

  By obtaining the bonded web 10b having high shape retention by the hot air blowing process described above, the draw ratio of the bonded web 10b between the hot air blowing part 40 and the embossed part 50 can be reduced. The ability to reduce the draw ratio is very advantageous in that the bulkiness of the connecting web 10b can be maintained. The draw ratio here is a value defined by the ratio (v2 / v1) of the speed v2 of the conveyor belt 42 to the circumferential speed v1 of the embossing roll 51.

  The temperature of the hot air described above is measured at a position 10 cm above the bonding web 10b. As the measuring means, for example, a thermocouple type temperature sensor and a temperature indicator are used.

  The temperature of the hot air blown onto the web 10a is as described above, and it is preferable that the speed of the hot air is such that the web 10a can be penetrated to the extent that the web 10a is not crushed by the wind pressure. By passing the hot air through the web 10a, it becomes possible to effectively prevent the elongation of the heat-extensible raw fiber from becoming uneven in the thickness direction of the web 10a. Further, it is possible to effectively prevent fuzz from occurring on the connecting web 10b. From these viewpoints, the hot air blowing speed is preferably set to 0.5 to 3.0 m / sec, particularly 1.0 to 2.0 m / sec. The speed of the hot air was measured at a position 10 cm away from the bonding web 10b. As a measuring means, for example, a thermal anemometer is used.

  In the bonded web 10b, the first surface 101, which is the hot air blowing surface, has more fiber fluff than the second surface 102, which is the opposite surface. This fluffing is suppressed by embossing by the embossing unit 50 described below.

  The bonded web 10b is processed in the embossed portion 50, whereby the target nonwoven fabric 10 is obtained. The embossing part 50 is provided with a pair of rolls 51 and 52 arranged to face each other with the coupling web 10b interposed therebetween. The roll 51 is made of a metal embossing roll having a large number of irregularities on its peripheral surface. The uneven pattern in the embossing roll can be appropriately selected according to the specific use of the nonwoven fabric 10. For example, when the rhomboid emboss pattern shown in FIG. 1 is formed, convex portions having a shape corresponding to the rhombus lattice may be formed on the peripheral surface of the roll 51. Further, when it is desired to form a dot-like emboss pattern (not shown) on the nonwoven fabric 10, a convex portion having a shape corresponding to the dot may be formed on the peripheral surface of the roll 51. On the other hand, the roll 52 is a flat roll having a smooth peripheral surface. The roll 52 is made of metal, rubber, paper, or the like.

  In the embossing part 50, embossing is performed by pinching the combined web 10b with both rolls 51 and 52. Specifically, the heat-extensible raw material fiber, which is a constituent fiber of the bonded web 10b, is consolidated by heat-consolidating to form a joined portion composed of a large number of embossed portions on the bonded web 10b. To manufacture. The roll 51 and the roll 52 have a heatable structure. During the operation of the embossing unit 50, the embossing roll 51 is heated to a predetermined temperature, and the flat roll 52 is also heated as necessary. The bonded web 10b to be embossed is in a bulky state because the heat-extensible raw fiber is stretched by the previously blown hot air. When the bonded web 10b is embossed, Unevenness is formed on the surface. The unevenness state is substantially the same on both sides, but the first surface 101, which is the surface with which the embossing roll 51 abuts, may have a slightly higher unevenness.

  The embossing is performed for the purpose of reducing fluff by pressing down the fluff generated on the coupling web 10 b, particularly the fluff generated on the first surface 101, with the concave portion of the emboss roll 51. For this purpose, the first surface 101 which is the hot air blowing surface in the coupling web 10b is brought into contact with the embossing roll 51, and the second surface which is the opposite surface to the hot air blowing surface is made to the flat roll 52. Make contact. The embossing roll is set to a melting point of the low melting point component of −20 ° C. or higher and a melting point of the low melting point component of + 20 ° C. or lower, and is set to a normal temperature (20 ° C.) or higher and a melting point of the low melting point component of + 20 ° C. or lower. Embossing with a flat roll.

  If the heating temperature of the embossing roll 51 is less than the melting point of the low melting point component of −20 ° C., the effect of suppressing fuzz in the bonded web 10b is not sufficiently exhibited. On the other hand, when the heating temperature of the embossing roll 51 exceeds the melting point + 20 ° C. of the low melting point component, the fuzzing suppression effect is sufficient, but the heat-extensible raw fiber is excessively melted and the texture of the nonwoven fabric 10 is lowered. Resulting in. As for the flat roll 52, when the heating temperature exceeds the melting point of the low melting point component + 20 ° C., the heat-extensible raw fiber is excessively melted and the texture of the nonwoven fabric 10 is lowered. From these viewpoints, the heating temperature of the embossing roll 51 is preferably a melting point of the low melting point component of −10 ° C. or more and a melting point of + 15 ° C. or less, more preferably a melting point of the low melting point component of −5 ° C. or more and a melting point. + 10 ° C. or lower. On the other hand, the temperature of the flat roll 52 is preferably a melting point of the low melting point component of −15 ° C. or higher, and a melting point of the low melting point component of + 10 ° C. or lower, more preferably a melting point of the low melting point component of −5 ° C. or higher. The melting point of the melting point component + 5 ° C. or lower.

  In embossing, fluffing can also be suppressed by adjusting the unevenness depth of the peripheral surface of the embossing roll 51. Specifically, as the embossing roll 51, it is preferable to use the embossing roll 51 in which the height of the convex portion is set to 10 to 100% of the thickness (under 49 Pa load) of the combined web 10b. By using such an embossing roll 51, fuzzing can be more effectively suppressed without impairing the three-dimensional feeling (unevenness) of the nonwoven fabric 10. The height of the convex portion of the embossing roll 51 is the distance from the concave and convex valleys formed on the peripheral surface of the embossing roll 51 to the apex.

  In the embossing process, depending on the heating temperature of the embossing roll 51 and the flat roll 52, the heat-extensible raw fiber contained in the bonded web 10b may be thermally stretched. However, the main purpose of this processing is to suppress fuzz generated on the bonded web 10b, and it is not essential whether or not the bonded web 10b is thermally expanded in this processing. Even if the bonded web 10b is not thermally stretched in this processing, the properties of the target nonwoven fabric 10 are not inferior.

  The nonwoven fabric 10 thus obtained can be applied to various fields that take advantage of its uneven shape, bulkiness, and good touch. For example, surface sheets in the field of disposable hygiene articles such as disposable diapers and sanitary napkins, second sheets (sheets disposed between the surface sheet and the absorber), back sheets, leak-proof sheets, or personal wipes, It is suitably used as a skin care sheet, and further as an objective wiper. As previously shown in FIG. 1, the nonwoven fabric 10 obtained by this manufacturing method has an uneven | corrugated structure on both surfaces, and there is no substantial difference in the uneven | corrugated state of front and back. Therefore, the nonwoven fabric 10 is particularly suitable for an application using both front and back surfaces such as a wiper. Moreover, when using the nonwoven fabric 10 for absorbent articles, such as a sanitary napkin, in the nonwoven fabric 10, the surface which the embossing roll 51 contact | abutted, ie, the surface where fluffing was suppressed by the embossing roll 51, is a wearer. It is preferable to arrange on the absorbent body so as to face the skin.

  The nonwoven fabric 10 in a state before being used in these applications is generally stored in a state of being wound in a roll shape. Due to this, the bulk of the nonwoven fabric 10 is often reduced. Therefore, when the nonwoven fabric 10 is used, hot air is blown onto the nonwoven fabric 10 by an air-through method to recover the reduced bulk. preferable. In restoring the bulk, it is preferable to use hot air having a temperature lower than the melting point of the low-melting component in the heat-stretchable composite fiber and a temperature of the melting point −50 ° C. or higher as the hot air blown to the nonwoven fabric 10. As a method for recovering the bulk of such a nonwoven fabric, for example, the techniques described in JP 2004-137655 A, JP 2007-177364 A, and JP 2008-231609 A related to the earlier application of the applicant of the present application are used. Can be used.

  Next, 2nd and 3rd embodiment of the manufacturing method of this invention is described, referring FIG.3 and FIG.4. These embodiments will be described with respect to differences from the first embodiment described above, and the descriptions of the first embodiment will be applied as appropriate to points not specifically described. 3 and 4, the same members as those in FIGS. 1 and 3 are denoted by the same reference numerals.

  The manufacturing apparatus 20 shown in FIG. 3 is different from the manufacturing apparatus shown in FIG. 2 described above in the configuration of the embossing section 50. In detail, in the manufacturing apparatus shown in FIG. 2 described above, the first surface 101, which is the hot air blowing surface, in the coupling web 10b and the embossing roll 51 are in contact with each other. In the manufacturing apparatus of the embodiment, the first surface 101 that is the hot air blowing surface is in contact with the flat roll 52, and the second surface 102, which is the surface opposite to the hot air blowing surface, is in contact with the embossing roll 51. It touches. As described above in the description of the first embodiment, the second surface 102, which is the surface opposite to the hot air blowing surface, is less fuzzy than the first surface 101. The embossing is performed by bringing the embossing roll 51 into contact with the second surface 102 having a low degree of fluffing, so that the fluffing on the second surface 102 side can be further reduced. Therefore, in the nonwoven fabric 10 manufactured according to this embodiment, it is preferable to use the 2nd surface 102 which is a surface on the opposite side to the hot air blowing surface as a use surface. For example, when the non-woven fabric 10 is used as a top sheet of an absorbent article such as a sanitary napkin, for example, in the non-woven fabric 10, the surface of the absorbent body so that the surface on which the embossing roll 51 abuts faces the wearer's skin. It is preferable to arrange on top.

  The conditions for manufacturing the nonwoven fabric 10 using the manufacturing apparatus 20 shown in FIG. 3 can be the same as those in the first embodiment.

  The manufacturing apparatus shown in FIG. 4 is also different from the manufacturing apparatus shown in FIG. In detail, in the manufacturing apparatus of this embodiment, the embossing part 50 is provided with a pair of embossing rolls 51a and 51b. Flat rolls are not used. Both the embossing rolls 51a and 51b have a concavo-convex part so that the convex part of one embossing roll 51a and the convex part of the other embossing roll 51b always contact each other when they rotate in the direction indicated by the arrow in FIG. Is arranged. The method of bringing the pair of embossing rolls 51 and 51 ′ into contact in this manner is called a chip-to-chip method. By embossing the connecting web 10b by the tip-to-chip method, the connecting web 10b can be given a three-dimensional effect without further impairing the bulkiness of the connecting web 10b, and the fluffing can be further suppressed. It is done.

  The embossing rolls 51a and 51b may have different heights of the convex portions of the two rolls as long as the convex portions abut on each other in a tip-to-chip manner. From the viewpoint of producing the nonwoven fabric 10 that has no difference between the front and back surfaces, the heights of the convex portions in the embossing rolls 51a and 51b are preferably the same.

  In the present embodiment, the hot air blowing conditions can be the same as those in the first embodiment. The embossing conditions are such that the heating temperature of each embossing roll 51a, 51b is set to a melting point of -20 ° C or higher and a melting point + 20 ° C or lower of the low melting point component. Preferably, the melting point of the low melting point component is set to −10 ° C. or more and the melting point is set to + 15 ° C. or less, more preferably the melting point of the low melting point component is set to −5 ° C. or more and the melting point is set to + 10 ° C. or less. Within this temperature range, the heating temperatures of the embossing rolls 51a and 51b may be the same or different.

  According to this embodiment, since the joining web 10b is embossed by a chip-to-chip method, there is an advantage that the joining web 10b is not easily crushed during embossing. From this point of view, the height of the space formed in a state where both the embossing rolls 51a and 51b are in contact with each other by the tip-to-chip method is 10 to 100% of the thickness (under 49 Pa load) of the connecting web 10b, particularly 80 It is preferable to use the embossing rolls 51a and 51b in which the height of the convex portion is set so as to be ˜95%. The height of the space here refers to the valley of one embossing roll 51a and the valley of the other embossing roll 51b facing this valley when both the embossing rolls 51a and 51b are in contact with each other in a tip-to-chip manner. It is the distance between.

  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, although the recessed part of the nonwoven fabric 10 manufactured by the said embodiment was carrying out the shape which makes a rhombus lattice shape, it may replace with this and you may employ | adopt the dot-shaped recessed part disperse | distributed and arranged in the shape of a dot. Moreover, you may employ | adopt the shape which makes a square or rectangular lattice shape, or a tortoiseshell pattern.

  The nonwoven fabric 10 is not limited to a single layer structure, and may have a multilayer structure. Furthermore, another nonwoven fabric may be further laminated on the back surface 10b side of the nonwoven fabric 10.

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

[Example 1]
The single layer nonwoven fabric 10 shown in FIG. 1 was manufactured using the apparatus shown in FIG. The embossing roll 51 in the apparatus shown in FIG. 2 had a rhombus lattice-shaped convex part with a line width of 0.5 mm. The embossing rate in this nonwoven fabric 10 was 14%. A 4 dtex staple fiber having a core made of polyethylene terephthalate (melting point 258 ° C.) and a sheath made of high-density polyethylene (melting point 128 ° C.) was used as the heat-extensible raw fiber. The thermal elongation rate of the low-temperature thermally extensible raw fiber at 138 ° C. was 7.9%. Production was carried out under the conditions shown in Table 1 below to obtain a nonwoven fabric. In the obtained nonwoven fabric, the intersections of the heat-extensible fibers were fused.

[Example 2]
A nonwoven fabric was obtained in the same manner as in Example 1 except that the apparatus shown in FIG. 3 was used and the conditions shown in Table 1 below were adopted.

Example 3
A nonwoven fabric was obtained in the same manner as in Example 1 except that the apparatus shown in FIG. 4 was used and the conditions shown in Table 1 below were adopted.

[Comparative Example 1]
A nonwoven fabric was obtained in the same manner as in Example 1 except that the apparatus shown in FIG. 2 of Patent Document 1 (Japanese Patent Laid-Open No. 2005-350836) was used and the conditions shown in Table 1 below were adopted.

[Evaluation]
About the nonwoven fabric obtained by the Example and the comparative example, the unevenness | corrugation structure uniformity (h1 / h2) was measured with the method mentioned above, and the fuzz prevention property of an embossing roll contact surface, a texture, and conveyance of a web with the following method. Sex was evaluated. The results are shown in Table 1 below.

[Fuzz prevention of embossing roll contact surface]
The nonwoven fabric is folded in two along the MD direction so that the convex portions are on the outside. At this time, the center of the convex portion is made to be the apex of the bent nonwoven fabric. The state in which the nonwoven fabric was visually observed from the horizontal direction with the vertex facing upward was determined according to the following criteria.
○: Almost no fuzz.
Δ: Slightly fuzzy.
X: There are many fuzz.

[Texture]
Place the non-woven fabric on a flat table with the convex part facing up. Using 10 monitors, the following three criteria were used to evaluate the degree of softness when the non-woven fabric was lightly held by the back of the hand and the sheet was lightly held by the palm of the hand. The results are shown as an average of 10 people.
Criteria 3: The surface of the sheet is smooth and soft.
2: The surface of the sheet is slightly hard.
1: The surface of the sheet is hard and rough.
Evaluation result ○: Judgment average 2.5 or more, 3 or less △: Judgment average 1.5 or more, less than 2.5 ×: Judgment average 1 or more, less than 1.5

[Web transportability]
The state of the nonwoven fabric sticking to the embossing roll 51 and the flat roll 52 was observed. The judgment criteria are as follows.
○: Non-woven fabric sticking to the roll is not observed, and conveyance is stable.
Δ: Non-woven fabric sticking to the roll is partially observed, and conveyance is unstable.
X Sticking of the nonwoven fabric to the roll is seen on the entire surface, and conveyance is unstable.

  As is clear from the results shown in Table 1, it can be seen that the nonwoven fabric obtained in each example has higher uniformity of the uneven structure and is superior in fuzz prevention properties as compared with the nonwoven fabric obtained in the comparative example. . Further, it can be seen that the web transportability is also good.

DESCRIPTION OF SYMBOLS 10 Nonwoven fabric 18 Concave part 19 Convex part 20 Manufacturing apparatus 30 Web manufacturing part 40 Hot air blowing part 50 Embossing part

Claims (6)

Hot air is blown to the web containing the high melting point component and the low melting point component having a lower melting point and the length is increased by heating, and the intersections between the constituent fibers of the web are fused. To form a bonded web in which the constituent fibers are bonded,
It is a method of embossing a bonded web with an embossing device comprising an embossing roll having irregularities on the peripheral surface and a flat roll having a smooth peripheral surface, and producing a nonwoven fabric having irregularities on the surface,
The temperature of the hot air blown to the web is set to be equal to or higher than the melting point of the low melting point component and lower than the melting point of the high melting point component,
In the embossing process, the hot air blowing surface of the bonded web is brought into contact with the embossing roll, and the surface opposite to the hot air blowing surface is brought into contact with the flat roll.
Embossing is performed with an embossing roll set at a melting point of −20 ° C. or more of the low melting point component and a melting point of + 20 ° C. or less and a flat roll set at a normal temperature or more and a melting point of the low melting point component of + 20 ° C. or less. Nonwoven fabric manufacturing method.   The manufacturing method of Claim 1 using the embossing roll by which the height of the convex part was set to 10 to 100% of the thickness (under 49 Pa load) of a joint web. Hot air is blown to the web containing the high melting point component and the low melting point component having a lower melting point and the length is increased by heating, and the intersections between the constituent fibers of the web are fused. To form a bonded web in which the constituent fibers are bonded,
It is a method of embossing a bonded web with an embossing device comprising an embossing roll having irregularities on the peripheral surface and a flat roll having a smooth peripheral surface, and producing a nonwoven fabric having irregularities on the surface,
The temperature of the hot air blown to the web is set to be equal to or higher than the melting point of the low melting point component and lower than the melting point of the high melting point component,
In the embossing process, the hot air blowing surface in the combined web is brought into contact with the flat roll, and the surface opposite to the hot air blowing surface is brought into contact with the embossing roll,
Embossing is performed with an embossing roll set at a melting point of −20 ° C. or more of the low melting point component and a melting point of + 20 ° C. or less and a flat roll set at a normal temperature or more and a melting point of the low melting point component of + 20 ° C. or less. Nonwoven fabric manufacturing method.   The manufacturing method of Claim 3 using the embossing roll by which the height of the convex part was set to 10 to 100% of the thickness (under 49 Pa load) of a joint web. Hot air is blown to the web containing the high melting point component and the low melting point component having a lower melting point and the length is increased by heating, and the intersections between the constituent fibers of the web are fused. To form a bonded web in which the constituent fibers are bonded,
A pair of embossing rolls having irregularities on the peripheral surface, and the embossing device provided with an embossing roll in which the irregularities are arranged so that the convexities in each embossing roll come into contact with each other, It is a method of embossing with a chip method to produce a nonwoven fabric having irregularities on the surface,
The temperature of the hot air blown to the web is set to be equal to or higher than the melting point of the low melting point component and lower than the melting point of the high melting point component,
A method for producing a nonwoven fabric, in which embossing is performed with each embossing roll set to a melting point of -20 ° C or higher and a melting point of + 20 ° C or lower.   The height of the convex portion is set so that the height of the space formed in a state where both embossing rolls are in contact with each other by the tip-to-chip method is 10 to 100% of the thickness of the combined web (under 49 Pa load). The manufacturing method of Claim 5 using the set embossing roll.

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