JP2010138529A - Method for producing nonwoven fabric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method by which a bulky nonwoven fabric having a good feeling can be produced. <P>SOLUTION: The method for producing the nonwoven fabric 43 includes: holding a web 40 containing heat-fusible fibers between a pair of embossing rolls 21 and 22; forming an embossed sheet 42 in which embossed parts 41 are formed; and then heating the embossed sheet 42. The peripheral surfaces of the embossing rolls 21 and 22 are uneven shapes, and protruding parts of the other embossing roll 22 are formed corresponding to protruding parts of the one embossing roll 21. When holding the web 40, the rotation of both the embossing rolls 21 and 22 is controlled so that the protruding parts of the one embossing roll 21 always oppose to the protruding parts of the other embossing roll 22. The embossed sheet 42 is heated without supporting the central zone of the embossed sheet 42 with a supporting member. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a nonwoven fabric. The nonwoven fabric produced according to the method of the present invention is particularly useful as a constituent material for hygiene articles, for example.

  A pair of embossing rolls having a plurality of convex portions formed on the peripheral surface is rotated by positioning so that the convex portions always face each other, and a plurality of sheets are sandwiched between the rolls to form a joint concave portion. Technology is known. This technique is known as so-called chip-to-chip embossing. An example of such a technique is an embossing roll described in Patent Document 1. In this embossing roll, the top surface of the convex portion of one roll and the top surface of the convex portion of the other roll corresponding to this convex portion have different sizes in the direction along the rotation axis or the circumferential direction of the roll. ing. Specifically, the top surface of the convex portion of one roll protrudes outside the top surface of the other convex portion on both sides in the direction along the rotation axis, or the convex surface of the other roll. The top surface protrudes outside the top surface of one convex portion on both sides in the circumferential direction of the roll. According to the description of the same document, it is said that the strength reduction of the joint recess can be prevented by using the roll having the above-described configuration. However, the technique described in this document is intended to improve the strength when joining a plurality of sheets, and has not been studied from the viewpoint of obtaining a nonwoven fabric with a good texture.

  Apart from the technology related to embossing, the present applicant has previously proposed a nonwoven fabric including a heat-extensible fiber whose length is increased by heating and a method for producing the same (see Patent Documents 2 and 3). A web is formed using these fibers, and after being partially bonded to the web at a large number of bonding points, by applying heat, the fibers between the bonding points are elongated to form a concavo-convex structure. However, since the bonding point forming methods described in these documents are embossed by a combination of a smooth roll and an emboss roll, the texture of the nonwoven fabric obtained by heat received from the smooth roll may be lowered.

JP 2008-132631 A JP 2005-350836 A JP 2007-130800 A

  An object of the present invention is to provide a method capable of producing a nonwoven fabric having various performances further improved as compared with the above-described prior art.

The present invention is a nonwoven fabric manufacturing method in which a web containing heat-fusible fibers is sandwiched between a pair of embossing rolls to form an embossed sheet on which a plurality of embossed portions are formed, and then the embossed sheet is heated.
Each of the embossing rolls has a concavo-convex shape on the peripheral surface, and the convex portions of the other embossing roll are formed corresponding to the convex portions of the one embossing roll,
The rotation of both embossing rolls is controlled so that the convex part of one embossing roll and the convex part of the other embossing roll always face each other when the web is pinched,
A non-woven fabric manufacturing method for heating an embossed sheet without supporting a central region of the embossed sheet with a support member.

  According to the present invention, it is possible to produce a nonwoven fabric that is bulky and has a good texture.

  The present invention will be described below based on preferred embodiments with reference to the drawings. FIG. 1 schematically shows an apparatus suitably used in the production method of the present invention. The manufacturing apparatus 10 shown in FIG. 1 is roughly provided with an embossing part 20 and a hot air blowing part 30. Details of each part will be described below.

  The embossing unit 20 includes a pair of embossing rolls including a first embossing roll 21 and a second embossing roll 22. The embossing rolls 21 and 22 rotate in opposite directions with their outer peripheral surfaces facing each other while aligning their rotation axes in parallel. Each of the embossing rolls 21 and 22 includes a heater (not shown), and the heater can heat the first embossing roll 21 and / or the second embossing roll 22 as necessary.

  The peripheral surface of each embossing roll 21 and 22 is uneven. The concave and convex portions and concave portions of the first embossing roll 21 are regularly arranged. The concave and convex convex portions and concave portions of the second embossing roll 22 are formed corresponding to the convex portions and concave portions of the first embossing roll 21.

  The convex portions on the emboss rolls 21 and 22 may be dot-like ones arranged in a dotted pattern, or may be protrusions extending in the axial direction or the circumferential direction of the roll. When the convex portion is dot-shaped, the shape of the convex portion in plan view can be various shapes such as a circle, an ellipse, a polygon, a star, etc., or a combination thereof. it can. When the convex portion is a ridge, the ridge may be a straight line or a curved line.

The size, the number, the arrangement density, and the like of the protrusions in each of the emboss rolls 21 and 22 are related to the texture and strength of the resulting nonwoven fabric. From the viewpoint of obtaining a non-woven fabric having a good texture while ensuring a strength that can withstand practical use, the size of the convex portion is 0.2 to ²⁰ mm ² in plan view when the convex portion is in the form of a dot, and particularly preferably 0.8. It is preferable that it is 8-3.0 mm < ² >. Moreover, it is preferable that the ratio (convex part area ratio) of the sum total of the area in the planar view of a convex part with respect to the apparent area of the whole surrounding surface of a roll is 8 to 25%, especially 10 to 15%. According to the production method of the present invention, a nonwoven fabric having a good texture can be obtained. Therefore, even if the convex area ratio is increased to increase the strength of the nonwoven fabric, there is an advantage that the texture of the nonwoven fabric is hardly impaired.

  The shape and size of the protrusions in each of the emboss rolls 21 and 22 can be made different in the rolls 21 and 22 as described in Patent Document 1 described above, but finally obtained. From the viewpoint of improving the bulkiness and texture of the nonwoven fabric, it is preferable that the shape and size of the protrusions in the embossing rolls 21 and 22 are the same.

  The hot air blowing unit 30 includes a hood 31. A pair of hot air blowing devices 32 and 33 are disposed in the hood 31. Each blowing device 32, 33 includes a plurality of nozzles 34, 35. Both blow-off devices 32 and 33 are installed in the hood 31 so that the nozzles 34 and 35 provided in them are opposed to each other. Each nozzle 34 and 35 is arrange | positioned so that a hot air may be sprayed over the substantially front width | variety of an embossed sheet | seat.

  When the manufacturing method of the nonwoven fabric using the above apparatus is demonstrated, the fiber web 40 used as a raw material will be manufactured first. The fiber web is a fiber assembly in which the constituent fibers are gently entangled and itself does not have shape retention as a sheet. Therefore, the nonwoven fabric having shape retention as a sheet does not correspond to the web referred to in the present invention. For example, a card machine can be used for manufacturing the fiber web. Moreover, a fiber web can also be manufactured by the airlaid method or the spunbond method.

  The fiber web 40 contains heat-fusible fibers. The heat-fusible fiber is a fiber that can be fused to each other by applying heat. The fiber web 40 may be composed only of heat-fusible fibers, or may contain other types of fibers in addition to the heat-fusible fibers. In the latter case, the ratio of fibers other than the heat-fusible fiber can be about 20 to 50% by weight based on the weight of the fiber web 40. The kind and ratio of the fiber to be used can be appropriately determined according to the specific use of the target nonwoven fabric. Examples of the fiber other than the heat-fusible fiber include non-heat-fusible and hydrophilic fibers such as rayon.

  In particular, the fiber web 40 preferably includes heat-extensible fibers whose length is increased by heating. This is because the presence of the heat-extensible fibers makes it possible to easily obtain a non-woven fabric with a remarkable degree of unevenness on the surface and a high bulkiness. The heat-extensible fiber may or may not have heat-fusibility. It is preferable that the heat-extensible fiber has heat-fusibility because a nonwoven fabric can be obtained using only the heat-extensible fiber. When the fiber web 40 contains heat-extensible fibers, the higher the proportion of the heat-extensible fibers in the fiber web 40, the more the degree of unevenness on the surface and the more bulky nonwoven fabric that can be made easier. It is preferable because it can be obtained.

  The thickness of the fibers constituting the fiber web 40 is not critical in the production method of the present invention, and an appropriate thickness is selected according to the specific use of the target nonwoven fabric. In general, by using fibers having a fineness of 1.0 to 10 dtex, particularly 2.0 to 5.0 dtex, a nonwoven fabric having satisfactory characteristics can be obtained. The length of the fibers constituting the fiber web 40 is not critical in the present invention. For example, when short fibers having a fiber length of up to about 64 mm are used as a raw material, the fiber web 40 may be manufactured using a card machine or may be manufactured using an airlaid method. When long fibers are used as a raw material, a spunbond method may be used.

  As the heat-fusible fiber contained in the fiber web 40, a core-sheath type composite fiber having a high melting point resin as a core and a low melting point resin as a sheath can be used. A side-by-side type composite fiber made of a high melting point resin and a low melting point resin can also be used.

  When heat-extensible fibers are included in the fiber web 40, those fibers described in Patent Documents 2 and 3 described above can be used without particular limitation. The heat-extensible fibers described in these documents are multicomponent composite fibers (core-sheath type composite fibers, side-by-side type composite fibers, etc.), and are also heat-fusible fibers. The heat-extensible fiber has a thermal elongation rate of 3% or more, particularly 8% or more measured at a temperature 10 ° C. higher than the melting point of the resin having the lowest melting point among the multicomponent resins constituting it. However, it is preferable from the viewpoint of easily obtaining a nonwoven fabric having a high bulkiness. The thermal elongation rate can be measured according to the method described in Patent Document 2.

  The 1st resin component in a heat | fever extensible fiber is a component which expresses the heat | fever extensibility of this fiber, and a 2nd resin component is a component which expresses heat-fusibility. The first resin component preferably has an orientation index of 30 to 70%, more preferably 30 to 65%, more preferably 30 to 60%, and particularly preferably 35 to 55%. Yes. On the other hand, the second resin component has an orientation index of preferably 40% or more, and more preferably 50% or more. There is no restriction | limiting in particular in the upper limit of the orientation index of a 2nd resin component, but it is so preferable that it is high, but if it is about 70%, the effect which can be fully satisfied is acquired. The orientation index is an index of the degree of orientation of the polymer chain of the resin constituting the fiber. And when the orientation index of a 1st resin component and a 2nd resin component is each said value, a heat | fever extensible fiber comes to expand | extend by heating. In addition, it is possible to form a fusion point with high heat and low strength.

The orientation index of the first resin component and the second resin component is expressed by the following formula (1), where A is the birefringence value of the resin in the heat-extensible conjugate fiber, and B is the intrinsic birefringence value of the resin. expressed.
Orientation index (%) = A / B × 100 (1)

Intrinsic birefringence refers to birefringence in the state where the polymer polymer chains are perfectly oriented. The values are, for example, the first edition of “Plastic Materials in Molding”, and the typical plastic materials used in molding processes (plastics). Edited by the Japan Society for Molding and Processing, Sigma Publishing, published on February 10, 1998). The birefringence in the heat-extensible composite fiber is measured under polarization in a direction parallel to and perpendicular to the fiber axis by attaching a polarizing plate to an interference microscope. As the immersion liquid, a standard refraction liquid manufactured by Cargille is used. The refractive index of the immersion liquid is measured with an Abbe refractometer. From the interference fringe image of the composite fiber obtained by the interference microscope, the refractive index in the direction parallel and perpendicular to the fiber axis is obtained by the calculation method described in the following document, and the birefringence that is the difference between the two is calculated.
“Fiber structure formation in high-speed spinning of core-sheath type composite fiber”, page 408 (Journal of the Fiber Society, Vol. 51, No. 9, 1995)

  In order to obtain a heat-extensible fiber having the above-described heat-extension rate, it is only necessary to crimp the fiber and not perform the drawing process after the melt-spinning of the heat-extensible fiber. As the crimping process performed after melt spinning, it is convenient to perform mechanical crimping. There are two-dimensional and three-dimensional forms of mechanical crimps, and there are three-dimensional manifested crimps found in eccentric core-sheath composite fibers and side-by-side composite fibers. In the present invention, any type of crimping may be performed. In the crimping process, the fiber may be somewhat stretched, but such stretching is not included in the stretching process referred to in the present invention. The drawing treatment referred to in the present invention refers to a drawing operation with a draw ratio of 2 to 6 times that is usually performed on undrawn yarn.

  As the heat-extensible fiber, a core-sheath type or a side-by-side type can be used. As the core-sheath type heat-extensible fiber, a concentric type or an eccentric type can be used. In particular, the core-sheath type is preferable. In this case, it is preferable that the first resin component constitutes a core and the second resin component constitutes a sheath from the viewpoint of increasing the thermal elongation rate of the thermally extensible composite fiber. There is no restriction | limiting in particular in the kind of 1st resin component and 2nd resin component, What is necessary is just resin with fiber formation ability. In particular, the difference between the melting points of the two resin components, or the difference between the melting point of the first resin component and the softening point of the second resin component is 10 ° C. or more, particularly 20 ° C. or more. This is preferable because it can be performed. When the heat-extensible fiber is a core-sheath type, a resin having a melting point of the core component higher than the melting point or softening point of the sheath component is used. As a preferable combination of the first resin component and the second resin component, as the second resin component when the first resin component is polypropylene (PP), high-density polyethylene (HDPE), low-density polyethylene (LDPE), Examples include linear low density polyethylene (LLDPE), ethylene propylene copolymer, and polystyrene. When a polyester resin such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT) is used as the first resin component, polypropylene (PP) is added as the second component in addition to the above-described example of the second resin component. And copolyester. Furthermore, examples of the first resin component include polyamide-based polymers and two or more types of copolymers of the first resin component described above, and examples of the second resin component include two or more types of the second resin component described above. Copolymers are also included. These are appropriately combined. Of these combinations, it is preferable to use polypropylene (PP) / high density polyethylene (HDPE). This is because the non-woven fabric can be easily manufactured because the difference in melting point between both resin components is in the range of 20 to 40 ° C. In addition, since the specific gravity of the fiber is low, a nonwoven fabric that is lightweight and excellent in cost and can be incinerated and discarded with a low heat quantity is obtained.

Regardless of whether or not heat-extensible fibers are included, the basis weight of the fiber web 40 is not critical in the present invention, and an appropriate value is selected according to the specific use of the target nonwoven fabric. In general, satisfactory results are obtained when the basis weight is about 20 to 60 g / m ² .

  The fiber web 40 is placed on a support 50 made of a wire mesh or the like, conveyed, and introduced into the embossing unit 20. In the embossing part 20, the fiber web 40 is passed between a pair of embossing rolls 21, 22 that are installed with a predetermined gap therebetween, and pinching by both the rolls 21, 22 is performed. In the pair of embossing rolls 21 and 22, the rotation of both embossing rolls 21 and 22 is controlled so that the convex part of one embossing roll 21 and the convex part of the other embossing roll 22 always face each other. As a result, so-called chip-to-chip embossing is performed. The rotation can be easily controlled by a control device usually used in the technical field.

  A plurality of embossed portions 41 are formed on each surface of the fiber web 40 by chip-to-chip embossing. Thereby, the embossed sheet 42 is obtained. The obtained embossed sheet 42 has a long strip shape. In the embossed sheet 42, the embossed part 41 formed on one surface thereof and the embossed part 41 formed on the other surface are present at the same position in the plan view of the embossed sheet 42. According to the chip-to-chip embossing, the embossed sheet 42 has an advantage that each surface thereof has an uneven shape. The concave portion in the concavo-convex shape is derived from the embossed portion 41, and the convex portion is configured from a portion other than the embossed portion 41. Therefore, in the embossed sheet 42, the convex portion formed on one surface thereof and the convex portion formed on the other surface are present at the same position in the plan view of the embossed sheet 42. It is very advantageous that each surface of the embossed sheet 42 has a concavo-convex shape by embossing from the viewpoint of making the finally obtained nonwoven fabric highly bulky.

  Further, according to the embossing of the chip-to-chip, since the convex portions formed on the embossed sheet 42 can be made to have a low fiber density, there is also an advantage that the texture of the finally obtained nonwoven fabric is improved. . In addition, the tip-to-chip embossing reduces the area where the fiber web 40 contacts the peripheral surface of the roll, making the fiber less susceptible to thermal damage and ultimately resulting in The texture of the resulting nonwoven fabric is improved. Furthermore, from the viewpoint of manufacturing, the tip-to-tip embossing process makes it difficult for the fiber web 40 to stick to the peripheral surface of the roll, so there is no need to set a large draw ratio, resulting in dimensional stability. There is also an advantage that becomes higher. In contrast to chip-to-chip embossing having such various advantages, in general embossing using an embossing device composed of a combination of a smooth roll and an embossing roll, fibers that are pinched between the rolls The fiber density of the web tends to be high, and the resulting nonwoven fabric tends to be hard. Further, since the fiber web is in contact with the smooth roll over the entire surface, the fiber is likely to be thermally damaged, and the nonwoven fabric tends to be hard due to this. Furthermore, since the fiber web tends to stick to the smooth roll, it is necessary to set a large draw ratio, and the dimensional stability tends to be lowered due to this.

  In the process in the embossing part 20, at least one of the embossing rolls 21 and 22 is heated. The heating temperature T1 is preferably set to [Mp-20] (° C.) to Mp (° C.) with respect to the melting point Mp (° C.) of the heat-fusible fiber contained in the fiber web 40. When the heat-fusible fiber is a composite fiber made of two or more kinds of resins, the melting point Mp means the melting point of the resin having the lowest melting point. Similarly, when the fiber web 40 contains heat-extensible fibers, the heating temperature T1 is set to [Mp-20 with respect to the melting point Mp (° C.) of the heat-extensible fibers contained in the fiber web 40. ] (° C.) to Mp (° C.). At this point, there is not much elongation of the heat-extensible fiber. This is because (i) the heat transfer from the portions other than the convex portions of the embossing rolls 21 and 22 to the heat-extensible fibers is insufficient, and (b) the melting point Mp of the heat-extensible fibers at this point. This is because the fibers are pressed into the recesses of the embossing roll 21 even if the heat treatment is performed at a temperature of 5 ° C., thereby preventing the elongation of the heat-extensible fibers. Therefore, a bulky nonwoven fabric cannot be obtained only by the treatment in the embossed portion 20.

  The melting point was determined by performing thermal analysis of a finely cut fiber sample (sample mass 2 mg) at a heating rate of 10 ° C./min using a differential scanning thermal analyzer DSC-50 (manufactured by Shimadzu Corporation). The peak temperature is measured and defined by its melting peak temperature.

  In the processing in the embossed portion 20, pressure is applied to the fiber web 40 together with heat. As the degree of pressure, an appropriate value is selected according to the specific use of the target nonwoven fabric. The degree of pressure can be controlled by adjusting the cylinder pressure of the embossing unit.

  The embossed sheet 42 formed in the embossing unit 20 is then conveyed to the hot air blowing unit 30. In this case, the embossed sheet 42 is conveyed in an unsupported state without being placed on a support made of a wire mesh or the like. Hot air is blown from both sides of the embossed sheet 42 conveyed into the hot air blowing unit 30. As a result, the embossed sheet 42 is heated. In particular, when heat-extensible fibers are included in the embossed sheet 42, the heat-extensible fibers at the convex portions located between the embossed portions 41 are elongated by heating. The stretched fiber loses its place due to the restriction by the embossed portion 41 and rises in the thickness direction of the embossed sheet 42. Thereby, the bulkiness of the convex portion is increased as compared with before hot air is blown. In particular, since hot air is blown from both surfaces of the embossed sheet 42, the unevenness of each surface of the sheet 42 increases and the bulkiness is further increased.

  In the hot air blowing unit 30, it is important that the embossed sheet 42 is heated without supporting at least the central region (the central region in the width direction) with any support member. This makes it difficult for the stretch of the heat-stretched fibers to be hindered on each surface of the embossed sheet 42, and the unevenness of the unevenness is further increased. In this case, the entire embossed sheet 42 may be in an unsupported state, but in that case, since the conveyance stability of the sheet 42 is likely to be lowered, both side edges along the longitudinal direction of the sheet 42 are used as a tenter or the like. It is advantageous to transport the sheet 42 while being gripped by the gripping member used.

  From the viewpoint of ensuring the running stability of the sheet 42, it is preferable that the hot air is blown from each surface of the embossed sheet 42 so that the amount of blowing air is substantially equal. When the air volume is substantially balanced, the hot air does not substantially penetrate the embossed sheet 42. When the sheet 42 is conveyed with the central region of the embossed sheet 42 being in an unsupported state, the blowing device 32 that blows hot air from the lower side to the upper side, and the blowing device 32 that blows hot air from the upper side to the lower side. It is preferable from the viewpoint of stable running of the seat 42 that the air volume is larger than the air volume.

  It is preferable that the temperature of the hot air sprayed on each surface of the embossed sheet 42 is substantially equal. This is because the unevenness on each surface of the sheet 42 is almost the same. On the contrary, when it is desired to intentionally change the unevenness state on each surface of the embossed sheet 42, the temperature of the hot air blown on each surface of the sheet 42 may be changed.

  The temperature of the hot air blown onto the embossed sheet 42 is determined in relation to the melting point of the heat-extensible fibers contained in the sheet 42. Specifically, the temperature of the hot air may be a temperature of [Mp−20] (° C.) or more and [Mp + 20] (° C.) or less with respect to the melting point Mp of the heat-extensible fiber. When obtaining a bulkier nonwoven fabric, it is preferable to blow hot air having a temperature equal to or higher than the melting point Mp of the heat-extensible fiber.

  In the hot air blowing part 30, the heat-extensible fibers are mainly stretched, and the heat-fusible fibers (which may be the same as the heat-extensible fibers) included in the embossed sheet 42 are substantially bonded. It is preferable not to cause it to occur. However, when the formation of the embossed portion 41 in the embossed portion 20 performed earlier is insufficient, the heat-fusible fiber is again heat-fused in the hot air blowing portion 30 to finally obtain the nonwoven fabric. You may make it ensure intensity | strength.

The target nonwoven fabric 43 is obtained by the above process. The nonwoven fabric 43 has a plurality of embossed portions 41 on both surfaces thereof, and the embossed portions 41 on each surface are present at the same position in a plan view of the nonwoven fabric 43. Moreover, the nonwoven fabric 43 has a bulky convex part with low fiber density between the embossed parts 41 on each surface, and the convex part on each surface is present at the same position in a plan view of the nonwoven fabric 43. Although the degree of bulkiness of the nonwoven fabric 43 depends on its constituent fibers, the specific volume under a load of 50 Pa is as high as 70 to 100 cm ³ / g. The specific volume is obtained by dividing the thickness of the nonwoven fabric 43 under a load of 50 Pa by the basis weight of the nonwoven fabric 43.

  The nonwoven fabric thus obtained is suitably used as a member that comes into contact with the skin of the wearer in an absorbent article such as a sanitary napkin or a disposable diaper, taking advantage of its good texture and bulkiness. An example of such a member is a surface sheet. In addition to the topsheet, it can also be used as a sublayer sheet that is a member disposed between the topsheet and the absorber, and can also be used as a part of the absorber. Furthermore, as an application other than the absorbent article, it can also be used for, for example, a surgical gown, a personal wiping sheet, a skin care sheet, an objective wiper, and the like.

  As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to the said embodiment. For example, in the above embodiment, hot air is blown from both sides of the embossed sheet 42, but hot air may be blown from only one side of the sheet 42 instead.

  Moreover, in the said embodiment, although hot air was sprayed in order to heat the embossing sheet | seat 42, it may replace with this and may use infrared rays etc. as a heating source.

  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]
A core-sheath type composite fiber having the first resin component as a core and the second resin component as a sheath in the resin component shown in A of Table 1 below was produced. This fiber was subjected to a drawing process after a mechanical crimping process. The core-sheath type composite fiber was cut to obtain a short fiber having a fiber length of 51 mm. A web having a basis weight of 40 g / m ² was prepared by a card machine using the obtained short fibers. The obtained web was subjected to the process shown in FIG.

  The two embossing rolls used in the embossing part 20 are the same. The convex part was a rhombus lattice-like continuous line pattern, and the convex part area ratio was 14%. Both embossing rolls were heated to 120 ° C. and used. The linear pressure was 100 kg / cm. Embossing was chip-to-chip.

  The embossed sheet 42 conveyed to the hot air blowing unit 30 was gripped on both sides in the longitudinal direction with a tenter. The central region in the width direction of the embossed sheet 42 was not supported. Hot air heated to 137 ° C. was blown onto each surface of the embossed sheet 42. The wind speed of the hot air was 2 m / sec, and the air volume was set to be the same on each surface of the embossed sheet 42. Thus, the nonwoven fabric by which the uneven | corrugated shape was provided to each surface was obtained.

[Examples 2 and 3]
A nonwoven fabric having a concavo-convex shape on each surface was obtained in the same manner as in Example 1 except that fibers shown in B (Example 2) and C (Example 3) in Table 1 were used. In addition, in the fiber C used in Example 3, after performing the mechanical crimping process, it was not subjected to the stretching process. The orientation index of the first resin component was 46%, and the orientation index of the second resin component was 41%.

[Comparative Examples 1 to 3]
In Examples 1 to 3, a nonwoven fabric was obtained in the same manner as in Examples 1 to 3 except that one of the embossing rolls was changed to a smooth roll.

[Evaluation]
About the nonwoven fabric obtained by the Example and the comparative example, texture evaluation was performed with the following method. Further, the thickness under a load of 50 Pa and the specific volume under the same load were determined by the above-described method. The results are shown in Table 2.

[Evaluation of texture]
Five panelists made sensory evaluation. The surface of the non-woven fabric was lightly wiped with the back of the hand, and the non-woven fabric was lightly grasped with the palm of the hand, and the degree of smoothness and softness was sensoryly evaluated. Judgment criteria are as follows.
○: Both sides of the nonwoven fabric are smooth and soft.
Δ: One side of the nonwoven fabric is smooth and soft, but the other side is somewhat hard.
X: Both surfaces of the nonwoven fabric are hard and rough.

  As is apparent from the results of Examples 1 to 3, it can be seen that a nonwoven fabric that is bulky and has a good texture can be obtained by producing a nonwoven fabric according to the method of the present invention. In particular, as is clear from the comparison between Examples 1 and 2 and Example 3, it can be seen that when the method of the present invention is carried out using heat-extensible fibers, the specific volume is further increased and the bulkiness is increased.

FIG. 1 is a schematic view showing a production apparatus suitable for carrying out the method of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Manufacturing apparatus 20 Embossing part 21, 22 Embossing roll 30 Hot air blowing part 31 Hood 32, 33 Hot air blowing apparatus 34, 35 Nozzle 40 Fiber web 41 Embossed part 42 Embossed sheet 43 Nonwoven fabric

Claims (3)

A method for producing a nonwoven fabric in which a web containing heat-fusible fibers is sandwiched between a pair of embossing rolls to form an embossed sheet in which a plurality of embossed portions are formed, and then the embossed sheet is heated.
Each of the embossing rolls has a concavo-convex shape on the peripheral surface, and the convex portions of the other embossing roll are formed corresponding to the convex portions of the one embossing roll,
The rotation of both embossing rolls is controlled so that the convex part of one embossing roll and the convex part of the other embossing roll always face each other when the web is pinched,
The manufacturing method of the nonwoven fabric which heats this embossed sheet, without supporting the center area | region of the said embossed sheet with a supporting member.   The manufacturing method according to claim 1, wherein the web includes heat-extensible fibers whose length is extended by heating, and the fibers are extended by heating the embossed sheet to raise between the embossed portions.   The manufacturing method according to claim 2, wherein hot air is blown from both sides of the embossed sheet to heat the embossed sheet, and the embossed portions are raised on each side of the embossed sheet.

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