JP5655116B2 - Elastic nonwoven fabric - Google Patents

Description

  The present invention relates to a stretchable nonwoven fabric.

  Conventionally, non-woven fabrics are used in a wide range of fields, such as absorbent articles such as disposable diapers and sanitary napkins, cleaning articles such as wipers, and medical articles such as masks. In this way, non-woven fabrics are used in various different fields, but when actually used in products in each field, they must be manufactured to have properties and structures suitable for the use of each product. It is.

  For example, in order to use for an absorbent article, the nonwoven fabric used is required to expand and contract in accordance with the movement of the wearer's body during or during wearing without causing the wearer to feel uncomfortable. Furthermore, for example, when used as a disposable diaper, the nonwoven fabric is required to have a strength such that the sheet does not break when stretched while maintaining stretchability, and also has good touch and breathability.

  Here, the nonwoven fabric which improved the feeling and the elasticity by extending | stretching the partially fused mixed fiber is disclosed. The nonwoven fabric disclosed in Patent Literature 1 is obtained by stretching partially mixed fiber by using two or more nip rolls and increasing the rotational speed of the nip rolls in the order of the flow direction of the apparatus (for example, , See Patent Document 1).

JP 2004-244791 A

However, the non-stretched nonwoven fabric (latent stretchable nonwoven fabric) disclosed in Patent Document 1 has a large fiber diameter of 24 to 26 μm, and has a low basis weight of 50 g / m ² or less which is not disclosed in Patent Document 1. When trying to stretch, a portion having a low basis weight was partially expressed. As described above, when the portion having a low basis weight is partially developed, the nonwoven fabric breaks due to the above-mentioned reason when trying to stretch at a higher magnification, and a predetermined elongation that can be used for a worn article is exhibited. I couldn't let you.

  The present invention has been made in view of the above problems, and has a high stretch range even when using a non-woven fabric with a low basis weight, and suppresses breakage and strength reduction that may occur during the stretching process, as well as the touch (cushioning property). It is an object of the present invention to provide a non-woven fabric with excellent air permeability.

  In the stretchable nonwoven fabric formed by mixing or laminating stretchable fibers and stretchable fibers, the present inventors form stretchable fibers having a reduced fiber diameter so that they are arranged at predetermined sites. Can provide a non-woven fabric with excellent touch (cushioning properties) and high air permeability, and even in non-woven fabrics with a low basis weight, it has a high stretch range during use and suppresses breakage and strength reduction due to stretching treatment. As a result, the present invention has been completed. Specifically, the following nonwoven fabric is provided.

  (1) A plurality of strip-like sparse regions and a plurality of strip-like dense regions that have a longitudinal direction and a transverse direction orthogonal to the longitudinal direction and extend in the longitudinal direction on both surfaces are alternately and continuously formed in the transverse direction. In addition, the band-like dense region on one surface and the belt-like dense region on the other surface are alternately formed in the transverse direction, and the stretchable nonwoven fabric is mixed or laminated stretched The stretchable fiber comprises a stretchable fiber partially stretched between the band-like dense region on the one surface and the belt-like dense region on the other surface. An elastic nonwoven fabric having an average fiber diameter of 12 to 21 μm.

(2) The elastic nonwoven fabric according to (1), wherein the elastic nonwoven fabric has a basis weight of 50 g / m ² or less.

  (3) The stretchable nonwoven fabric according to (1) or (2), wherein the stretchable fiber causes plastic deformation with an elongation smaller than the stretch at the maximum strength of the stretchable fiber.

  (4) The stretchable nonwoven fabric according to any one of (1) to (3), wherein the extensible fiber is a thermoplastic polyolefin fiber.

  (5) A composite sheet obtained by bonding a non-stretchable nonwoven fabric to the stretchable nonwoven fabric according to any one of (1) to (4) with an adhesive.

  (6) A composite sheet obtained by laminating the stretchable nonwoven fabric according to any one of (1) to (4) with at least one article selected from nonwoven fabrics and films other than the stretchable nonwoven fabric.

  (7) An absorbent article comprising at least an absorbent body and the stretchable nonwoven fabric described in (1) to (4).

  (8) An absorbent article comprising at least an absorbent body and the composite sheet according to (5) or (6), wherein the composite sheet is on the skin contact surface side when the absorbent article is mounted Absorbent article placed in the.

  (9) An absorbent article comprising at least a chassis having a front body and a back body, and a liquid-retaining absorbent, wherein the chassis is composed of at least the stretchable nonwoven fabric or the composite sheet. The absorbent article as described in (7) or (8).

  (10) After applying a calorific value not higher than the melting point of the extensible fiber and not lower than the melting point of the extensible fiber to the latent stretchable nonwoven fabric obtained by mixing or laminating the stretchable fiber having a crystallinity of 57% or less and the stretchable fiber The manufacturing method of the elastic nonwoven fabric which performs mechanical extending | stretching.

  (11) The stretchable nonwoven fabric as described in (10) manufactured by the said manufacturing method.

  (12) An absorbent article using the stretchable nonwoven fabric according to (11).

  According to the present invention, in the stretchable nonwoven fabric formed by mixing or laminating stretchable fibers and stretchable fibers, the stretchable fibers having a reduced fiber diameter are formed so as to be arranged at predetermined sites. Can provide a non-woven fabric with excellent touch (cushioning properties) and high air permeability, and even in non-woven fabrics with a low basis weight, it has a high stretch range during use and suppresses breakage and strength reduction due to stretching treatment. The nonwoven fabric which can be provided can be provided.

It is a perspective view of the elastic nonwoven fabric 1 which concerns on this invention. It is sectional drawing which uses the fiber state of the elastic nonwoven fabric 1. FIG. It is a figure which shows the relationship between the expansion-contraction range of the elastic nonwoven fabric 1 after an extending | stretching process, and the extending | stretching process magnification which should be provided to the nonwoven fabric sheet 2 before an extending | stretching process. It is a figure which shows the structure of the polyolefin fiber with respect to the elongation in the horizontal direction of the elastic nonwoven fabric 1. FIG. It is a figure which shows the relationship between a crystallinity degree and the distortion after 100% cycle of the single fiber of a polyolefin fiber. It is a figure explaining the manufacturing method of the elastic nonwoven fabric. (A) is a figure explaining the state which carried out the gear extension process of the nonwoven fabric sheet 2, (B) is the elements on larger scale of the meshing part in (A). It is a figure which shows the relationship between the fiber diameter in the elastic nonwoven fabric 1, and a basic weight, and a compression work rate. It is a figure which shows the relationship between the fiber diameter and basic weight in the elastic nonwoven fabric 1, and ventilation resistance value. It is a figure which shows the relationship between the intensity | strength in the horizontal direction of a nonwoven fabric sheet 2, and a processing speed. It is a figure which shows the relationship between the intensity | strength in the horizontal direction of the nonwoven fabric sheet 2, and the temperature of the nonwoven fabric sheet. It is a front view which shows the underpants type disposable diaper 50 which is an example of the absorbent article using the composite sheet 4 which bonded the elastic nonwoven fabric 1 of this invention with the non-elastic nonwoven fabric. It is an expanded view of the disposable diaper 50.

  Hereinafter, embodiments of the present invention will be described. In the present invention, stretchable fibers and stretchable fibers are mixed, and self-melting due to softening or melting is performed in a large number of fusion portions in which the stretchable fibers and the stretchable fibers are arranged at a predetermined interval. The nonwoven fabric sheet, which is a latent stretchable nonwoven fabric fixed by wearing, is stretched to form a stretchable nonwoven fabric. The extensible fiber includes, for example, a fiber that causes plastic deformation with an elongation smaller than the elongation at the maximum strength of the elastic fiber. For example, the extensible fiber is a fiber that can be stretched inelastically, and the stretchable fiber includes a fiber that can be stretched elastically.

  Moreover, in this embodiment, since the nonwoven fabric sheet 2 is heated in the below-mentioned gear extending | stretching process, it demonstrates using a thermoplastic polyolefin fiber as an extensible fiber.

  FIG. 1 is a perspective view of a stretchable nonwoven fabric 1 according to the present invention. FIG. 2 is a cross-sectional view using the fiber state of the stretchable nonwoven fabric 1. FIG. 3 is a diagram showing the relationship between the stretch range of the stretchable nonwoven fabric 1 after the stretching treatment and the stretch treatment magnification to be applied to the nonwoven fabric sheet 2 before the stretching treatment. FIG. 4 is a view showing the configuration of the polyolefin fiber with respect to the elongation in the transverse direction of the stretchable nonwoven fabric 1. FIG. 5 is a diagram showing the relationship between crystallinity and strain rate after 100% cycle of single fibers of olefin fibers. FIG. 6 is a diagram for explaining a method for producing the stretchable nonwoven fabric 1. FIG. 7A is a diagram for explaining a state in which the nonwoven fabric sheet 2 is subjected to gear stretching, and FIG. 7B is a partially enlarged view showing the meshing portion of FIG. FIG. 8 is a diagram showing the relationship between the fiber diameter and basis weight of the stretchable nonwoven fabric 1 and the compression power. FIG. 9 is a diagram showing the relationship between the fiber diameter and basis weight of the stretchable nonwoven fabric 1 and the airflow resistance value. FIG. 10 is a diagram showing the relationship between the strength in the lateral direction of the stretchable nonwoven fabric 1 and the processing speed of the nonwoven fabric sheet 2. FIG. 11 is a diagram showing the relationship between the strength of the stretchable nonwoven fabric 1 in the lateral direction and the temperature of the nonwoven fabric sheet 2. FIG. 12 is a front view showing a pants-type disposable diaper 50 which is an example of an absorbent article using the composite sheet 4 in which the stretchable nonwoven fabric 1 of the present invention is bonded to a non-stretchable nonwoven fabric. FIG. 13 is a development view of the disposable diaper 50.

[Elastic nonwoven fabric]
The stretchable nonwoven fabric 1 according to this embodiment will be described with reference to FIGS. 1 and 2.

  As shown in FIG. 1, the stretchable nonwoven fabric 1 has a longitudinal direction and a lateral direction, and is formed in a sheet shape. The stretchable nonwoven fabric 1 is formed by mixing stretchable thermoplastic polyolefin fibers 21 and stretchable thermoplastic elastomer fibers 22, and a plurality of strip-like sparse stretches in the longitudinal direction on both sides thereof. The sparse regions 11 as regions and the dense regions 12 as a plurality of band-like dense regions extending in the vertical direction are alternately formed. And the dense region 12 on one surface and the dense region 12 on the other surface are arranged so that the dense regions 12 provided on one surface and the other surface are alternately arranged in the lateral direction of the stretchable nonwoven fabric 1. Is formed. Similarly, the sparse region 11 on one surface and the sparse region 11 on the other surface are alternately arranged in the lateral direction of the stretchable nonwoven fabric 1 with the sparse regions 11 provided on one surface and the other surface. Is formed.

  The stretchable nonwoven fabric 1 is given stretchability by subjecting the nonwoven fabric sheet 2 to a gear stretching process that is mechanical stretching. Specifically, the stretchable nonwoven fabric 1 is formed by passing the nonwoven fabric sheet 2 through a gap between a pair of gear rolls 31 and 32 in a gear stretching process described later. That is, the nonwoven fabric sheet 2 is squeezed into a three-point bent shape by the gear teeth 31 t and 32 t formed on the gear rolls 31 and 32, whereby the polyolefin fibers 21 and the elastomer fibers 22 are elongated. A dense region 12 is formed in the stretchable nonwoven fabric 1 squeezed by the apex portions of the gear teeth 31t and 32t meshed with each other. Thereby, in the dense region 12, polyolefin fibers 21 that have been compressed by the gear teeth 31t and 32t and have not been elongated are disposed.

  Further, the polyolefin fiber 21 is stretched and loosened by the meshed gear teeth 31t and 32t at the portions of the stretchable nonwoven fabric 1 that are not squeezed by the gear teeth 31t and 32t (the portions that contact the side surfaces of the gear teeth 31t and 32t). Region 11 is formed. That is, in the sparse region 11, a polyolefin fiber 21 stretched by a gear drawing process described later is disposed.

  Thereby, the dense region 12 contains more polyolefin fibers 21 that have not been stretched than the sparse region 11, and the sparse region 11 contains polyolefin fibers 21 that have been stretched by gear drawing described later than the dense region 12. Many are included.

  Further, as shown in FIG. 2, the elastomer fiber 22 in the sparse region 11 contracts and returns to the original fiber length even after the gear stretching process, but the polyolefin fiber 21 stretched by the gear stretching process is the original fiber length. It does not return to the fiber length but is at least partially stretched by gear stretching. And it will be in the state swollen in the thickness direction centering | focusing on the melt | fusion part 23 by the part which was extended. That is, the sparse region 11 becomes thick as the stretchable nonwoven fabric 1. This is because the polyolefin fibers 21 are elongated, so that the voids in the stretchable nonwoven fabric 1 are larger than before the gear stretching.

  When the stretchable nonwoven fabric formed in this way is released from the stretched state, an stretch margin is formed by the stretchability of the elastomer fiber 22 and the stretched polyolefin fiber 21, thereby being stretchable. Moreover, in the sparse area | region 11, the thickness by a space | gap becomes thick and the touch (cushion property) improves.

  Further, the stretched polyolefin fiber 21 has a smaller fiber diameter in the stretched portion. The fiber diameter of the elongated polyolefin fiber is preferably 12 to 21 mm. For example, if the thickness is 12 μm or less, the polyolefin fiber 21 may be broken during use, and if it is 21 μm or more, the density of the stretchable nonwoven fabric increases, so that the cushioning property and air permeability may be reduced. Because there is.

The stretchable nonwoven fabric 1 can be used for a nonwoven fabric formed with the above-described fiber configuration and having a basis weight of 50 g / m ² or less when relaxed. Specifically, it can be used for a nonwoven fabric of 50 to 15 g / m ² . For example, if the basis weight of the stretchable nonwoven fabric 1 is 15 g / m ² or less, the stretchable nonwoven fabric 1 may be easily broken, and the stretchable nonwoven fabric 1 is bonded to a non-stretchable sheet. This is because when used as a composite sheet, the adhesive used at the time of bonding may ooze out.

Moreover, the base weight at the time of relaxation of the polyolefin fiber 21 in the elastic nonwoven fabric 1 can illustrate the range of 4-40 g / m < ² >. This is because when it is less than 4 g / m ² , it is difficult to obtain a good texture, and when it is greater than 40 g / m ² , the stretchable nonwoven fabric 1 is rigidly finished. Moreover, 3-38 g / m < ² > can illustrate the basic weight of the elastomer fiber 22 in the elastic nonwoven fabric 1. When it is less than 3 g / m ² , it is difficult to obtain sufficient stretchability as the stretchable nonwoven fabric 1, and when it is greater than 38 g / m ² , the stretchable stress is too strong when used as the stretchable nonwoven fabric 1, making it difficult to use. Because.

  Furthermore, when the stretchable nonwoven fabric 1 is formed under the above conditions, the amount of strain in the 100% cycle test of the stretchable nonwoven fabric 1 is preferably 20% or less. This is because when the strain amount exceeds 20%, the shrinkage dimension of the product is not stable, and there is a possibility that a variation in wearing feeling may occur when the stretchable nonwoven fabric 1 is used for an absorbent article.

  Moreover, as the thermoplastic polyolefin fiber 21 in this embodiment, single fiber, such as a polypropylene fiber and a polyethylene fiber, the composite fiber of the core-sheath structure which consists of polypropylene and polyethylene, etc. can be used, for example.

  Moreover, as the elastomer fiber 22 used for the stretchable nonwoven fabric 1, for example, fibers such as urethane elastomer, polystyrene elastomer, polyolefin elastomer, polyamide elastomer, polyester elastomer, and the like can be used. Specifically, a polyurethane elastomer can be used.

  Moreover, 80: 20-25: 75 can be illustrated for the mixing rate (weight ratio) of the polyolefin fiber 21 and the elastomer fiber 22. If the mixing ratio of the polyolefin fibers 21 is larger than 80%, the elastic nonwoven fabric 1 may be distorted. On the contrary, if the mixing ratio of the elastomer fibers 22 is larger than 75%, the tactile feeling may be sticky. It is.

  Next, the case where it aims at using the elastic nonwoven fabric 1 which concerns on this invention for the disposable diaper 50 which is an absorbent article is demonstrated. FIG. 12 is a front view showing a pants-type disposable diaper 50 which is an example of an absorbent article using the composite sheet 4 in which the stretchable nonwoven fabric 1 of the present invention is bonded to a non-stretchable nonwoven fabric. It is an expanded view of the disposable diaper 50. The disposable diaper 50 includes a chassis 54 forming a main body, a liquid-permeable surface sheet 51 disposed on the skin contact surface side of the chassis 54, and a liquid impermeability disposed on the non-skin contact surface side of the chassis 54. And a liquid-retaining absorbent core 52 sandwiched between the top sheet 51 and the chassis 54.

  The chassis 54 is formed in a pants shape with a front body 55 and a back body 56, and has a front waist gather 57 that forms the end of the front body 55 and a rear waist gather 58 that forms the end of the back body 56. A substantially U-shaped cut portion 59 is formed inside the chassis 54 at both edges in the vertical direction of the chassis 54 and having the approximate center in the horizontal direction as a vertex. The notch 59 forms a leg opening 60 when the front body 55 and the back body 56 of the chassis 54 are joined to each other by a joint 63 to form a pants shape. Also, the waist opening 61 is formed by joining the front body 55 and the back body 56 together.

  And in this embodiment, the composite sheet 4 which has a stretching property is used as the chassis 54, and it arrange | positions so that the below-mentioned flow direction may become the width direction of FIG. For this reason, elastic members such as rubber thread are not arranged in the waist gathers 57 and 58, and when the front body 55 and the back body 56 in such a chassis 54 are joined to form a pants, The front body 55 and the back body 56 are stretchable along the outer periphery of the pants due to the composite sheet 4. Therefore, the disposable diaper 50 has elasticity according to the movement of the body at the time of wearing operation or wearing. Thus, the physical irritation | stimulation to skin can be reduced by making an elastic member unnecessary. Of course, in this invention, you may arrange | position an elastic member to a waist gather or a leg gather as needed.

  In addition, in this embodiment, the composite sheet 4 is arrange | positioned so that the elastic nonwoven fabric 1 may become a skin contact surface, and the wrinkle by a non-elastic sheet has appeared on the surface as shown in FIG. By arranging the composite sheet 4 in this manner, the contact area ratio to the skin can be further increased.

Here, for example, when the elastic nonwoven fabric 1 is used for a disposable diaper, the elastic nonwoven fabric 1 needs to expand and contract at a lower strength (the strength at 75% elongation is 10 N / 50 mm). Is preferably 50 g / m ² or less. Further, at least the stretchable nonwoven fabric 1 after the stretching treatment requires a stretch range of 1.7 times or more (70%). In FIG. 3, the relationship between the expansion-contraction range (%) of the elastic nonwoven fabric 1 after an extending | stretching process and the extending | stretching process magnification (%) which should be provided to the nonwoven fabric sheet 2 before an extending | stretching process is shown.

  As shown in FIG. 3, in order to increase the expansion / contraction range of the stretchable nonwoven fabric 1 after the stretching treatment, it is necessary to form the nonwoven fabric sheet 2 so that it can be stretched more. That is, it is necessary to carry out a stretching process capable of high stretching on the nonwoven fabric sheet 2 before the stretching process. For example, in the stretchable nonwoven fabric 1 after the stretching treatment, at least 2.6 times (160%) stretching treatment is performed on the nonwoven fabric sheet 2 before stretching in order to have a stretch range of 1.8 times (80%) or more. There is a need to.

  However, when a highly stretched stretch treatment is performed on the nonwoven fabric sheet 2 before the stretch treatment, for example, when the material constituting the nonwoven fabric sheet 2 is an elastomer fiber 22 such as a urethane fiber and a polyolefin fiber 21, the elastomer fiber 22 The polyolefin fiber 21 has a lower fiber elongation and higher strength than the elastomer fiber 22, and therefore the fusion is a fusion part between the polyolefin fiber 21 and the elastomer fiber 22. There is a possibility that the fiber breakage or the fused part may be broken at the portion 23 or the like. As a result, fluff is likely to be generated by the cut fibers, and the stretchable nonwoven fabric 1 after the stretching process may have a reduced strength or may be broken during the process. Therefore, in order to carry out the high stretching treatment, an olefin fiber and a nonwoven fabric sheet 2 having a high elongation are required.

  In order to obtain such an olefin fiber having high extensibility, a method of obtaining a fiber having a relatively low spinning speed using a resin such as polypropylene or polyethylene, a polyethylene-polypropylene copolymer having a low crystallinity, Fibers can be obtained by dry blending polyethylene with polypropylene or spinning using olefin elastomer.

  Moreover, in order to increase the elongation of the nonwoven fabric sheet 2, the embossed area ratio may be decreased at the fusion part 23 between the elastomer fiber 22 and the polyolefin fiber 21, and the fiber is mechanically bonded instead of heat fusion. You may manufacture by the spunlace method to be entangled, or the needle punch method.

As shown in FIG. 4, the stretchable range of the stretchable nonwoven fabric 1 can also be increased by increasing the strain after the polyolefin fibers 21 are stretched. FIG. 4 shows the configuration of the polyolefin fiber 21 with respect to the elongation (%) in the transverse direction of the stretchable nonwoven fabric 1. Furthermore, the stretchable range of the stretchable nonwoven fabric 1 can be efficiently obtained by reducing the elastic recovery of the polyolefin fiber 21 as shown in the following mathematical formula and also at a low draw ratio.
(Equation 1)
Stretch range = Stretch ratio-Elastomer fiber (urethane fiber) strain-Polyolefin fiber elastic recovery Polyolefin fiber elastic recovery = Stretch ratio-Polyolefin fiber strain

  Furthermore, as shown in FIG. 5, in order to reduce the elastic recovery of the polyolefin fiber 21 and increase the strain, the crystallinity of the polyolefin fiber 21 may be reduced. FIG. 6 shows the relationship between the degree of crystallinity of polyolefin fibers and the strain rate after 100% cycle of single fibers of polyolefin fibers. When the degree of crystallinity is 57% or more, the distortion of the polyolefin fiber is reduced, it becomes difficult to obtain an expansion / contraction range, and the fiber strength is increased, so that the sheet elongation of the nonwoven fabric sheet 2 is likely to be lowered.

  In order to reduce the crystallinity of the fiber, the fiber draft ratio during spinning may be reduced, or spinning may be performed at a high temperature. As the resin to be used, a polyolefin copolymer having a relatively low orientation, a blend of polypropylene and polyethylene, an olefin-based elastomer, and the like can be used. A fiber having a low degree of crystallinity has a low elastic recovery and a high fiber elongation. Therefore, the nonwoven fabric sheet 2 composed of such fibers has a high sheet elongation and is unlikely to exhibit a decrease in strength during stretching. preferable.

[Production method]
Next, the manufacturing method of the elastic nonwoven fabric 1 is demonstrated.

  In FIG. 6, the figure explaining the manufacturing method of the elastic nonwoven fabric 1 is shown. As shown in FIG. 6, the stretchable nonwoven fabric 1 is manufactured from a nonwoven fabric roll (a nonwoven fabric sheet as a material is wound into a roll), and the nonwoven fabric sheet 2 is continuously fed in the flow direction in a sheet state. A non-woven sheet by applying a predetermined tension in the flow direction to the non-woven sheet 2 heated and heated, while the non-woven sheet 2 is heated while being moved in the flow direction. A preliminary stretching step for preliminarily stretching 2, a gear stretching step for stretching the preliminarily stretched nonwoven fabric sheet 2 in the flow direction by a gear roll, and a nonwoven fabric sheet 2 (stretchable nonwoven fabric 1) stretched by a gear roll ) And a winding step of winding the stretchable nonwoven fabric 1 that is the cooled nonwoven fabric sheet 2 into a roll.

  First, in the feeding process, the nonwoven fabric sheet 2 is fed from a nonwoven fabric roll provided with a reel device for feeding. Thereby, the fed-out nonwoven fabric sheet 2 is conveyed by predetermined | prescribed reference speed V1, and is sent to the heating process provided downstream in the flow direction in a sheet | seat state continuously.

  In the heating step, a heater for heating the nonwoven fabric sheet 2 to be conveyed is provided. Specifically, four heating rollers 33 are arranged. The nonwoven fabric sheet 2 is sequentially sent to each heating roller 33 while being wound in a substantially S shape around the smooth outer peripheral surface of each heating roller 33 in a sheet state. The nonwoven fabric sheet 2 is heated by the outer peripheral surface of the heating roller 33 while in contact with the smooth outer peripheral surface of the heating roller 33.

  Each heating roller 33 is provided with a heating element for heating the outer peripheral surface thereof, and by adjusting the amount of heat generated by this heating element, the temperature of the outer peripheral surface can be adjusted, and the nonwoven fabric sheet 2 The temperature can also be adjusted. Although the temperature of an outer peripheral surface and the temperature of the nonwoven fabric sheet 2 change with fiber composition of the nonwoven fabric sheet 2, in the case of a thermoplastic polyolefin fiber, it is adjusted to the temperature below the melting point based on the melting point of polyolefin fiber. For example, the temperature of the nonwoven fabric sheet 2 is not higher than the melting point of the polyolefin fiber, and is preferably 40 ° C. or higher. Below 40 ° C., the extensibility of the fibers is poor and the strength tends to decrease. Moreover, when it becomes more than melting | fusing point of an olefin fiber, there exists a possibility that a fiber may stick to the heating roller 33 or the gear rolls 31 and 32, and the nonwoven fabric sheet 2 may melt | dissolve and cut | disconnect at the time of an extending | stretching process.

  The nonwoven fabric sheet 2 heated by the heating process is sent to the preliminary stretching process. Here, the preliminary stretching is performed by setting the circumferential speed of the heating roller 33 in the heating process and the circumferential speed of the gear rolls 31 and 32 in the gear stretching process described later to different speeds. That is, the peripheral speed of the gear rolls 31 and 32 is set to be higher than the peripheral speed of the heating roller 33 in order to apply the tension for preliminary stretching to the nonwoven fabric sheet 2.

  In the present embodiment, a guide roller 34 is disposed between the heating roller 33 and the gear rolls 31 and 32 so as to guide the nonwoven fabric sheet 2 to the roll gap between the gear rolls 31 and 32. The nonwoven fabric sheet 2 is configured such that its flow direction is directed to the roll gap between the gear rolls 31 and 32 by being wound around the guide roller 34 by a predetermined winding angle.

  Moreover, in the preliminary | backup extending process, the nonwoven fabric sheet 2 is extended | stretched 1.1 to 1.8 times with respect to the flow direction by the circumferential speed difference of the above-mentioned heating roller 33 and the gear rolls 31 and 32, for example. In addition, if this draw ratio is enlarged, the tension | tensile_strength which acts on the nonwoven fabric sheet 2 will become large, and there exists a possibility of a fracture | rupture. However, in this embodiment, in the above-mentioned heating process, the nonwoven fabric sheet 2 is heated beforehand and the temperature of the nonwoven fabric sheet 2 is rising. Moreover, since the nonwoven fabric sheet 2 contains thermoplastic polyolefin fibers, the polyolefin fibers are easily plastically deformed by temperature. Thereby, the fracture | rupture of the nonwoven fabric sheet 2 in a predrawing process can be prevented. In addition, you may change suitably the draw ratio in a predrawing process according to other conditions.

  In the gear stretching step, the nonwoven fabric sheet 2 is further stretched in the flow direction by the gear rolls 31 and 32 in addition to the stretch amount stretched in the preliminary stretching step. Here, the gear extension will be described. As shown in FIG. 7 (A), the gear stretching is performed using a pair of gear rolls 31 and 32 having gear teeth 31t and 32t formed in a wave shape in the circumferential direction at a predetermined pitch P on the outer peripheral surface. That is, in the gear stretching, the nonwoven fabric sheet 2 is passed through the gap between the gear rolls 31 and 32, and the nonwoven fabric sheet 2 is bent at three points by the gear teeth 31t of the upper gear roll 31 and the gear teeth 32t of the lower gear roll 32 that mesh with each other. The nonwoven fabric sheet 2 is stretched in the flow direction.

When the nonwoven fabric sheet 2 is passed through the gap between the rolls, a part of the nonwoven fabric sheet 2 whose length before the gear stretching is the pitch P is partly meshed with the gear teeth 31t and 32t in FIG. 7B. As shown, it is deformed into a three-point bend and stretched. The change in this state can be expressed by a function of the draw ratio Mg of the nonwoven fabric sheet 2 by gear stretching, the pitch P of the gear teeth 31t and 32t, and the meshing margin L of the gear teeth 31t and the gear teeth 32t by the following formula. it can.
(Equation 2)
Mg = 2 × √ (L ² + (P / 2) ² ) / P

  In the gear stretching step, the stretched nonwoven fabric sheet 2 (stretchable nonwoven fabric 1) is sent to a cooling step for cooling the nonwoven fabric sheet 2 (stretchable nonwoven fabric 1) stretched by the gear rolls 31 and 32. In the cooling step, guide rollers 35 and 36 for guiding the stretched nonwoven fabric sheet 2 to the cooling device 37, and a cooling device 37 for cooling the stretched nonwoven fabric sheet 2 while transporting it in a sheet form, Guide rollers 38 and 39 for guiding the cooled stretchable nonwoven fabric 1 to a winding process for winding it into a roll are disposed.

  Here, since the stretched nonwoven fabric sheet 2 is quickly cooled to near normal temperature by the cooling device 37, the stretchable fibers that contribute to the development of stretchability of the stretchable nonwoven fabric 1 after stretching, that is, the plasticity of polyurethane fibers. Deformation is effectively suppressed. As a result, stretchability is effectively imparted to the stretchable nonwoven fabric 1 after gear stretching.

  In the cooling step, the cooled stretchable nonwoven fabric 1 is wound up in a roll shape by a winding reel device, and is carried out as a stretchable roll sheet.

  Thus, when heat is applied to the nonwoven fabric sheet 2 before the stretching treatment, the crystal structure in the polyolefin fiber changes, and the orientation of the fiber changes. Thereby, fiber elongation increases and the elongation in the nonwoven fabric sheet 2 tends to increase. Moreover, the fracture | rupture of the nonwoven fabric sheet 2 in each extending process can be prevented by heating the nonwoven fabric sheet 2. FIG.

  Moreover, since the crystallinity degree of an olefin fiber is low and the distortion rate of an olefin fiber is large, it is easy to obtain a high expansion / contraction range. Furthermore, since the nonwoven fabric sheet 2 having a high fiber elongation and a high sheet elongation can be obtained, a high stretch ratio can be imparted during gear stretching, a high stretch range can be obtained, and the sheet strength does not decrease. Thereby, even when it uses for a disposable diaper, for example, a diaper can be prevented from being torn at the time of pulling up at the time of wearing.

  Moreover, since it becomes possible to use a stretchable nonwoven fabric having a low basis weight, for example, even when used for a disposable diaper, the strength at the time of expansion and contraction becomes low, so that it becomes easy to spread when spreading a disposable diaper, and when worn Can reduce the tightening due to gathers, and can produce a diaper with higher wearability.

  In addition, after the gear stretching process, the fiber diameter of the olefin fiber is reduced, the fiber length is increased, and the density of the stretchable nonwoven fabric is decreased, so that a stretchable nonwoven fabric having good cushioning properties and excellent breathability can be obtained. it can.

  Moreover, the heat processing can be added to the nonwoven fabric sheet 2 before extending | stretching process, and the fall of the intensity | strength of the nonwoven fabric sheet 2 can be reduced by increasing a drawability. Thereby, for example, even when performing high-speed and high-magnification drawing, it can be carried out without causing fuzz and the like.

  In this embodiment, as a means for applying heat to the nonwoven fabric sheet 2, heat is applied by passing the nonwoven fabric sheet 2 through a heating roller 33 provided with a heating element. You may make it add heat by adding to.

  The stretch direction of the stretchable nonwoven fabric 1 can be arbitrarily formed depending on the purpose of use of the stretchable nonwoven fabric 1. That is, by arranging the nonwoven fabric sheet 2 in either the horizontal direction or the vertical direction with respect to the direction in which the gear teeth 31t, 32t are arranged when performing the gear stretching process, in either the horizontal direction or the vertical direction. Can be extended.

  For example, when the nonwoven fabric sheet 2 before the gear stretching process is disposed in the lateral direction with respect to the direction in which the gear teeth 31t and 32t are disposed when the gear stretching process is performed, the stretchable nonwoven fabric 1 can be stretched in the lateral direction. The stretchable nonwoven fabric 1 can be formed. Similarly, when the nonwoven fabric sheet 2 before the gear stretching process is disposed in the longitudinal direction with respect to the direction in which the gear teeth 31t and 32t are disposed when the gear stretching process is performed, the stretchable nonwoven fabric 1 can be stretched in the longitudinal direction. A stretchable nonwoven fabric 1 can be formed. Furthermore, the stretchable nonwoven fabric 1 that can be stretched in both directions can be formed by performing gear stretching in the lateral direction and the longitudinal direction.

  Examples according to the present invention will be described below. It should be noted that the following examples are merely examples for suitably explaining the present invention, and do not limit the present invention at all.

<Example 1>
A nonwoven fabric sheet made of polypropylene fibers (PP) having a fiber diameter of 23 μm and polyurethane fibers (TPU), having a basis weight of 27 g / m ² and a mixing ratio of polyurethane fibers (TPU) of 50% was prepared.
Next, as a gear stretching process for this nonwoven fabric sheet, a non-woven fabric sheet having a pitch P of 4.9 mm and a meshing margin L of 4.0 mm, a nonwoven fabric sheet temperature of 45 ° C., and a processing speed of 50 m / min. Gear stretching was performed to obtain a stretchable nonwoven fabric. The stretchable nonwoven fabric had a basis weight of 30.38 g / m ² and a stretch range of 62.1%. Moreover, the fiber diameter of the polypropylene fiber (PP) in the sparse area | region 11 was 20 micrometers.

(Change in cushioning property due to difference in fiber diameter and basis weight of elastic nonwoven fabric 1)
Using the resulting stretchable nonwoven fabric as a test piece, a compressibility test was performed using Kato Tech Co., Ltd. KES-FB3-AUTO-A. In the test, measurement was performed with a pressure area of 2 cm ² , SENS2, and a compression speed of 50 sec / mm, and the compression work WC in the compression process was calculated.

(Change in breathability due to difference in fiber diameter and basis weight of elastic nonwoven fabric 1)
Using the obtained non-woven fabric as a test piece, the ventilation resistance value was measured using Kato Tech Co., Ltd. KES-F8-AP1. In the measurement, a test piece was attached to a cylindrical portion of φ28 mm, and the ventilation resistance value after 3 sec of exhaust and 3 sec of intake was measured.

<Example 2>
A nonwoven fabric sheet made of polypropylene fibers (PP) having a fiber diameter of 23 μm and polyurethane fibers (TPU), having a basis weight of 27 g / m ² and a mixing ratio of polyurethane fibers (TPU) of 50% was prepared.
Next, as a gear stretching process for this nonwoven fabric sheet, a non-woven fabric sheet with a pitch P of 4.9 mm and a meshing margin L of 6.0 mm, a nonwoven fabric sheet temperature of 45 ° C., and a processing speed of 50 m / min. Gear stretching was performed to obtain a stretchable nonwoven fabric. The stretchable nonwoven fabric had a basis weight of 31.43 g / m ² and a stretch range of 125.5%. Moreover, the fiber diameter of the polypropylene fiber (PP) in the sparse area | region 11 was 17 micrometers.
The same test as Example 1 was done using the obtained elastic nonwoven fabric.

<Example 3>
A nonwoven fabric sheet made of polypropylene fibers (PP) having a fiber diameter of 23 μm and polyurethane fibers (TPU), having a basis weight of 27 g / m ² and a mixing ratio of polyurethane fibers (TPU) of 50% was prepared.
Next, as a gear stretching process for this nonwoven fabric sheet, a non-woven fabric sheet having a pitch P of 4.9 mm and a meshing margin L of 7.0 mm, a nonwoven fabric sheet temperature of 45 ° C., and a processing speed of 50 m / min. Gear stretching was performed to obtain a stretchable nonwoven fabric. The stretchable nonwoven fabric had a basis weight of 28.15 g / m ² and a stretch range of 164%. Moreover, the fiber diameter of the polypropylene fiber (PP) in the sparse region 11 was 16 μm.
The same test as Example 1 was done using the obtained elastic nonwoven fabric.

<Example 4>
A nonwoven fabric sheet made of polypropylene fibers (PP) having a fiber diameter of 23 μm and polyurethane fibers (TPU), having a basis weight of 35 g / m ² and a mixing ratio of polyurethane fibers (TPU) of 50% was produced.
Next, as a gear stretching process for this nonwoven fabric sheet, a non-woven fabric sheet having a pitch P of 4.9 mm and a meshing margin L of 4.0 mm, a nonwoven fabric sheet temperature of 45 ° C., and a processing speed of 50 m / min. Gear stretching was performed to obtain a stretchable nonwoven fabric. The stretchable nonwoven fabric had a basis weight of 38.45 g / m ² and a stretch range of 64.5%. Moreover, the fiber diameter of the polypropylene fiber (PP) in the sparse area | region 11 was 20 micrometers.
The same test as Example 1 was done using the obtained elastic nonwoven fabric.

<Example 5>
A nonwoven fabric sheet made of polypropylene fibers (PP) having a fiber diameter of 23 μm and polyurethane fibers (TPU), having a basis weight of 35 g / m ² and a mixing ratio of polyurethane fibers (TPU) of 50% was produced.
Next, as a gear stretching process for this nonwoven fabric sheet, a non-woven fabric sheet with a pitch P of 4.9 mm and a meshing margin L of 6.0 mm, a nonwoven fabric sheet temperature of 45 ° C., and a processing speed of 50 m / min. Gear stretching was performed to obtain a stretchable nonwoven fabric. The stretchable nonwoven fabric had a basis weight of 38.51 g / m ² and a stretch range of 120.9%. Moreover, the fiber diameter of the polypropylene fiber (PP) in the sparse area | region 11 was 17 micrometers.
The same test as Example 1 was done using the obtained elastic nonwoven fabric.

<Example 6>
A nonwoven fabric sheet made of polypropylene fibers (PP) having a fiber diameter of 23 μm and polyurethane fibers (TPU), having a basis weight of 35 g / m ² and a mixing ratio of polyurethane fibers (TPU) of 50% was produced.
Next, as a gear stretching process for this nonwoven fabric sheet, a non-woven fabric sheet having a pitch P of 4.9 mm and a meshing margin L of 7.0 mm, a nonwoven fabric sheet temperature of 45 ° C., and a processing speed of 50 m / min. Gear stretching was performed to obtain a stretchable nonwoven fabric. The stretchable nonwoven fabric had a basis weight of 35.67 g / m ² and a stretch range of 155.7%. Moreover, the fiber diameter of the polypropylene fiber (PP) in the sparse region 11 was 16 μm.
The same test as Example 1 was done using the obtained elastic nonwoven fabric.

<Example 7>
A nonwoven fabric sheet having a fiber diameter of 23 μm and polypropylene fibers (PP) and polyurethane fibers (TPU), a basis weight of 50 g / m ² , and a polyurethane fiber (TPU) mixing ratio of 40% was prepared.
Next, as a gear stretching process for this nonwoven fabric sheet, a non-woven fabric sheet having a pitch P of 4.9 mm and a meshing margin L of 4.0 mm, a nonwoven fabric sheet temperature of 45 ° C., and a processing speed of 50 m / min. Gear stretching was performed to obtain a stretchable nonwoven fabric. The stretchable nonwoven fabric had a basis weight of 52.13 g / m ² and a stretch range of 49.5%. Moreover, the fiber diameter of the polypropylene fiber (PP) in the sparse area | region 11 was 20 micrometers.
The same test as Example 1 was done using the obtained elastic nonwoven fabric.

<Example 8>
A nonwoven fabric sheet having a fiber diameter of 23 μm and polypropylene fibers (PP) and polyurethane fibers (TPU), a basis weight of 50 g / m ² , and a polyurethane fiber (TPU) mixing ratio of 40% was prepared.
Next, as a gear stretching process for this nonwoven fabric sheet, a non-woven fabric sheet with a pitch P of 4.9 mm and a meshing margin L of 6.0 mm, a nonwoven fabric sheet temperature of 45 ° C., and a processing speed of 50 m / min. Gear stretching was performed to obtain a stretchable nonwoven fabric. The stretchable nonwoven fabric had a basis weight of 55.98 g / m ² and a stretch range of 119.5%. Moreover, the fiber diameter of the polypropylene fiber (PP) in the sparse area | region 11 was 17 micrometers.
The same test as Example 1 was done using the obtained elastic nonwoven fabric.

<Example 9>
A nonwoven fabric sheet having a fiber diameter of 23 μm and polypropylene fibers (PP) and polyurethane fibers (TPU), a basis weight of 50 g / m ² , and a polyurethane fiber (TPU) mixing ratio of 40% was prepared.
Next, as a gear stretching process for this nonwoven fabric sheet, a non-woven fabric sheet having a pitch P of 4.9 mm and a meshing margin L of 7.0 mm, a nonwoven fabric sheet temperature of 45 ° C., and a processing speed of 50 m / min. Gear stretching was performed to obtain a stretchable nonwoven fabric. The stretchable nonwoven fabric had a basis weight of 50.34 g / m ² and a stretch range of 149.5%. Moreover, the fiber diameter of the polypropylene fiber (PP) in the sparse region 11 was 16 μm.
The same test as Example 1 was done using the obtained elastic nonwoven fabric.

<Evaluation>
As shown in FIG. 8, when the fiber diameter of the olefin fiber changes, the density of the stretchable nonwoven fabric 1 changes, and the voids of the stretchable nonwoven fabric 1 increase even if the basis weight is the same. Thereby, the compression work WC is also increased, and the cushioning property is increased because the stretchable nonwoven fabric is easily compressed.

  As shown in FIG. 9, since the density of the stretchable nonwoven fabric 1 is changed by changing the fiber diameter of the olefin fiber, the air permeability of the stretchable nonwoven fabric 1 is changed even if the basis weight is the same. And when the fiber diameter of an olefin fiber falls, a space | gap increases in the elastic nonwoven fabric 1, and ventilation resistance value reduces. Therefore, it can be seen that the air permeability increases.

<Example 10>
(Strength change under conditions during gear drawing)
A nonwoven fabric sheet composed of 60% polypropylene fiber having a fiber diameter of 23 μm and 40% polyurethane fiber and having a basis weight of 35 g / m ² was produced. Next, as a gear stretching process, the gear rolls 31 and 32 having a pitch P of 4.9 mm and a meshing margin L of 6.2 mm are used to perform a gear stretching process on the nonwoven fabric sheet 2 in the flow direction (MD direction) to expand and contract. The nonwoven fabric 1 was obtained. In addition, the heating process adjusted the sheet | seat temperature to 48 degreeC by allowing the nonwoven fabric sheet to pass the heating roller 33. FIG. The nonwoven fabric sheet had a maximum point strength in the MD direction of 45.9 N / 50 mm.

  Moreover, the flow direction of the equipment at the time of manufacturing a nonwoven fabric is Machine Direction (MD).

  At this time, the elastic nonwoven fabric 1 was obtained at each speed while changing the processing speed. The resulting stretchable nonwoven fabric 1 had a fiber diameter of polypropylene fiber (PP) in the sparse region 11 of 16 μm. Using the obtained stretchable nonwoven fabric 1, the maximum point strength in the MD direction was tested.

  Similarly, the elastic nonwoven fabric 1 was obtained while changing the sheet temperature of the nonwoven fabric sheet. The resulting stretchable nonwoven fabric 1 had a fiber diameter of polypropylene fiber (PP) in the sparse region 11 of 16 μm. Using the obtained stretchable nonwoven fabric 1, the maximum point strength in the MD direction was tested.

<Evaluation>
As shown in FIG. 10, in the gear stretching process, it can be seen that when the processing speed is 50 m / min or more, the strength in the flow direction is lower than that of the nonwoven fabric sheet before the gear stretching process. However, as shown in FIG. 11, by heating the nonwoven fabric sheet 2 at the time of gear stretching, it is understood that the strength in the flow direction can be increased even if the processing speed is 53 m / min.

1 Elastic nonwoven fabric 2 Nonwoven fabric sheet (latent elastic nonwoven fabric)
4 Composite sheet 11 Sparse area 12 Dense area 21 Polyolefin fiber (extensible fiber)
22 Elastomer fiber (stretchable fiber)
23 Fusion part 31, 32 Gear roll 31t, 32t Gear tooth 50 Disposable diaper P Pitch L Engagement allowance

Claims (5)

A vertical direction and a horizontal direction perpendicular to the vertical direction,
A plurality of strip-like sparse regions and a plurality of strip-like dense regions extending in the vertical direction on both sides are formed alternately and continuously in the lateral direction, and the belt-like dense regions on one surface and the belt-like dense regions on the other surface are formed. A stretchable nonwoven fabric in which regions are alternately formed in the transverse direction,
The stretchable nonwoven fabric consists of stretchable fibers and stretchable fibers mixed or laminated,
The extensible fiber includes extensible fibers partially elongated between the band-like dense region on the one surface and the band-like dense region on the other surface,
The strip-shaped sparse region is formed flat and thicker than the strip-shaped dense region,
The basis weight of the extensible fiber is 4 to 40 g / m ² ,
The elastic nonwoven fabric whose basic weight of the said elastic fiber is 3-38 g / m < ² >. The stretchable nonwoven fabric according to claim 1, wherein the stretchable nonwoven fabric has a basis weight of 15 to 50 g / m ² .   The stretchable nonwoven fabric according to claim 1 or 2, wherein the stretchable range is 1.7 times or more.   The stretchable nonwoven fabric according to any one of claims 1 to 3, which has a ventilation resistance value of 0.0101 to 0.0265 Kpa · sec / m. The elastic nonwoven fabric according to any one of claims 1 to 4, wherein the compression work is 0.78 to 1.44 N · m / m ² .

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