JP2007321291A - Stretchable nonwoven fabric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stretchable nonwoven fabric having much higher stretch characteristics than those of the conventional stretchable nonwoven fabrics. <P>SOLUTION: The stretchable nonwoven fabric has an elastic fiber layer containing elastic fibers containing a polyolefinic elastomer consisting essentially of ethylene and other elastic fibers different from the elastic fibers or non-elastic fibers. The polyolefinic elastomer has 0.855-0.895 g/cm<SP>3</SP>density thereof. The elastic fibers containing the polyolefinic elastomer are composed of only the polyolefinic elastomer or contain the polyolefinic elastomer and other thermoplastic elastomers. A non-elastic fiber layer substantially non-elastic may be arranged on at least one surface of the elastic fiber layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a stretchable nonwoven fabric.

  Various non-woven fabrics having stretch properties including fibers made of polyolefin-based copolymers are known. For example, Patent Document 1 describes a stretchable nonwoven fabric made of fibers containing a propylene / α-olefin random copolymer. This propylene / α-olefin random copolymer is polymerized by a metallocene catalyst, and the α-olefin content is 2 to 23 mol%. This nonwoven fabric exhibits stretchability by heat treatment. That is, the fiber containing the propylene / α-olefin random copolymer does not have elasticity itself. Therefore, this nonwoven fabric does not have sufficient stretch properties.

  Patent Document 2 discloses a composite elasticity having an anisotropic elastic fiber web having a first layer of elastomer meltblown fibers and a second layer of elastomer filaments bonded thereto, and a gatherable layer bonded to the webs. The materials are listed. The elastomer filament contains 40-80 wt% elastomer polymer and 5-40 wt% resin adhesive. As described above, since the elastomer filament contains a resin other than the elastomer resin, the stretch characteristic is not sufficient due to the resin.

JP 2003-49352 A Japanese Patent Laid-Open No. 5-27043

  Accordingly, an object of the present invention is to provide a stretchable nonwoven fabric in which various properties including stretchability are further improved.

The present invention includes an elastic fiber containing a polyolefin-based elastomer mainly composed of ethylene, and another elastic fiber or non-elastic fiber different from the elastic fiber,
The polyolefin elastomer achieves the object by providing a stretchable nonwoven fabric having a density of 0.855 to 0.895 g / cm ³ .

  The stretchable nonwoven fabric of the present invention has higher stretch properties than conventional stretchable nonwoven fabrics. Also, the tensile strength is increased. Furthermore, the polyolefin-based elastomer has high fusion properties with the inelastic fiber layer. As a result, when the non-elastic fiber layer is laminated on the elastic fiber layer, the bonding between both layers becomes good and delamination hardly occurs.

  Hereinafter, the present invention will be described based on preferred embodiments thereof. The stretchable nonwoven fabric of the present invention has an elastic fiber layer. The stretchable nonwoven fabric may be composed only of an elastic fiber layer, or a substantially inelastic nonelastic fiber layer may be laminated on at least one surface thereof as shown in FIG. The elastic fiber layer includes elastic fibers. An elastic fiber layer consists only of elastic fibers, or contains elastic fibers and non-elastic fibers. One type or two or more types of elastic fibers can be used. When inelastic fibers are contained in the elastic fiber layer, one type or two or more types of inelastic fibers can be used.

  At least one of the elastic fibers is an elastic fiber containing a polyolefin-based elastomer mainly composed of ethylene. The elastic fiber contained in the elastic fiber layer is only the elastic fiber containing the polyolefin-based elastomer or the elastic fiber and another elastic fiber different from the elastic fiber.

  The elastic fiber containing the polyolefin-based elastomer is composed only of the polyolefin-based elastomer, or is composed of the polyolefin-based elastomer and one or more other resins.

The polyolefin-based elastomer used in the present invention is characterized by a low density. The polyolefin-based elastomer is mainly composed of ethylene, that is, an ethylene / α-olefin copolymer. This polyolefin-based elastomer has a density of 0.855 to 0.895 g / cm ³ . The density in this range is at a low level as compared with the density of conventionally used polyethylene-based elastomers. By using an elastic fiber containing a polyolefin-based elastomer having such characteristics as a constituent resin, the stretchable nonwoven fabric of the present invention has higher stretchability than that of the conventional one.

  In addition to the low density within the above range, the polyolefin elastomer preferably has a low ethylene content. Specifically, the polyolefin elastomer preferably has an ethylene content of 70 to 90% by weight. The ethylene content in this range is at a low level as compared with the ethylene content of polyethylene elastomers conventionally used.

  In particular, the polyolefin-based elastomer has a low density and preferably has a low ethylene content, so that yarn breakage is less likely to occur when melt spinning an elastic fiber, and a thin continuous fiber is easily produced. can do. The ability to reduce the diameter of the elastic fiber greatly contributes to the improvement of stretchability. The fact that elastic fibers can be made into continuous fibers (filaments) also greatly contributes to the improvement of stretch properties. Further, when the polyolefin-based elastomer has a low density and preferably has a low ethylene content, the handleability of the elastic fiber itself (for example, it is difficult to stick) is improved. Furthermore, fuzz on the surface of the stretchable nonwoven fabric 10 is also suppressed. In addition, the tensile strength of the elastic fiber itself increases, and consequently the tensile strength of the stretchable nonwoven fabric also increases. Moreover, as will be described later, when the elastic fiber layer and the non-elastic fiber layer are laminated, the fusibility of both layers is increased.

  When the elastic fiber used in the present invention is melt-spun, it becomes difficult for yarn breakage to occur, which leads to less likely shots due to the yarn breakage. As a result, a non-woven fabric having a good touch can be obtained. A shot is like a lump of fibers caused by yarn breakage during melt spinning. If the fiber breaks during melt spinning, the broken fiber tends to shrink, and this occurs because the fiber is rounded and becomes a lump. When a shot occurs, the nonwoven fabric feels rough.

From the above viewpoints, when the density of the polyolefin-based elastomer is particularly 0.860 to 0.870 g / cm ³ , the above characteristics are further improved. Setting the ethylene content of the polyolefin-based elastomer to 75 to 80% by weight has the same effect.

The density of the polyolefin-based elastomer is measured according to JIS-K7112 C method (floating method). The density measurement environment is 20 ± 2 ° C. and 65 ± 2% RH, and ethanol / distilled water is used as the immersion liquid. Further, the ethylene content in the polyolefin elastomer is measured by the following method. A ¹³ C-NMR measurement is performed on the polyolefin-based elastomer. From the obtained NMR spectrum, the weight ratio between ethylene and the other α-olefin component is calculated. And let the thing which converted the weight ratio of ethylene into 100% be ethylene content rate.

  There is no particular limitation on the polymerization method of the polyolefin-based elastomer, but a metallocene catalyst is preferably used as the polymerization catalyst because the resulting polyolefin-based elastomer becomes homogeneous. As a polymerization method in the case of using a metallocene catalyst, a slurry method using an inert solvent, a gas phase method using no solvent, a bulk polymerization method using a monomer as a solvent, or the like can be used. Metallocene catalyst is a metallocene, which is a compound of a transition metal such as titanium, zirconium, hafnium, etc. sandwiched by an unsaturated cyclic compound containing a π-electron cyclopentadienyl group or substituted cyclopentadienyl group, and an aluminum compound. And a cocatalyst such as Examples of the metallocene include titanocene and zirconocene. Examples of the aluminum compound include alkylaluminoxane, alkylaluminum, aluminum halide, alkylaluminum halide and the like.

  Polyolefin elastomers have a melt flow rate (MFR) of 2 to 350/10 min, particularly 5 to 200 g / 10 min, which makes it more difficult for yarn breakage to occur when melt spinning elastic fibers, and for continuous finer diameters. This is preferable because the fiber can be easily produced. MFR is measured according to ASTM D-1238. The measurement conditions are 230 ° C. and a load of 2.16 kg.

  The polyolefin elastomer preferably has a heat of fusion value of 10 to 80 mJ / mg, particularly 20 to 40 mJ / mg. It is preferable for the heat of fusion value to be within the above-mentioned range since the stretchability is improved while the tensile strength is kept moderate and the melt spinnability is improved. The value of heat of fusion is determined by differential scanning calorimetry (DSC). The calorific value of melting is obtained from the calorific value at the endothermic peak appearing at 40-60 ° C. by obtaining a DSC curve while raising the temperature at 10 ° C./min.

  In addition to having the above-mentioned physical property values, the polyolefin-based elastomer preferably has the dynamic viscoelastic properties described below. As a result, the stretchable nonwoven fabric of the present embodiment including elastic fibers made of this polyolefin-based elastomer has a higher modulus and good stretch hysteresis compared to conventional stretchable nonwoven fabrics. The high modulus means that the basis weight of the stretchable nonwoven fabric is lowered for the purpose of improving the air permeability and the touch, and the nonwoven fabric is made thin or the fiber diameter of the elastic fiber is reduced. This is advantageous because good stretch properties are exhibited. That is, the stretchable nonwoven fabric becomes easy to stretch, and the strength when shrinking from the stretched state increases. Therefore, the stretchable nonwoven fabric of this embodiment containing elastic fibers composed of this polyolefin-based elastomer is particularly suitable as a sheet constituting the entire exterior surface of a pants-type disposable diaper, for example.

The polyolefin elastomer has a storage elastic modulus G ′ of dynamic viscoelasticity measured at 20 ° C. and a frequency of 2 Hz, preferably 1 × 10 ⁴ to 8 × 10 ⁶ Pa. In addition, the polyolefin elastomer has a dynamic loss tangent tan δ value of dynamic viscoelasticity measured at 20 ° C. and a frequency of 2 Hz, preferably 0.2 or less.

  The storage elastic modulus G ′ is an index representing an elastic component in dynamic viscoelasticity measurement of a polyolefin-based elastomer, that is, an index representing hardness. On the other hand, the dynamic loss tangent tan δ value is expressed by the ratio G ″ / G ′ of the storage elastic modulus G ′ and the loss elastic modulus G ″, and is an index indicating how much energy is absorbed when the polyolefin elastomer is deformed. is there. If the storage elastic modulus G ′ of the polyolefin-based elastomer is less than the above lower limit value, the modulus of elasticity is low, and the expansion / contraction hysteresis may not be sufficient. When the value of G ′ exceeds the upper limit value, the modulus is high, so that a large force is required at the time of extension, and there is a case where the feel is hard. On the other hand, when the dynamic loss tangent tan δ value of the polyolefin-based elastomer exceeds the above upper limit value, the residual strain when deformed becomes large, and the expansion and contraction characteristics may be insufficient.

  As described above, the dynamic viscoelasticity measurement of the polyolefin-based elastomer is performed in a tensile mode at 20 ° C., a frequency of 2 Hz. The applied strain is 0.1%. The specific measurement in this embodiment was performed using Physica MCR500 manufactured by Anton Paar. The sample was a plate having a length of 30 mm, a width of 10 mm, and a thickness of 0.8 mm.

  Examples of the α-olefin copolymerized with ethylene include α-olefins having 3 to 20 carbon atoms. For example, propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene and the like. These α-olefins can be used alone or in combination of two or more. Of these α-olefins, ethylene and 1-butene are particularly preferably used.

  The polyolefin-based elastomer preferably has a weight average molecular weight of 50,000 to 280,000, particularly 70,000 to 240,000.

  As described above, the elastic fiber containing the polyolefin-based elastomer may be composed of only the polyolefin-based elastomer as a resin component, or the polyolefin-based elastomer and one or more other resins. It may contain and may be comprised. In any case, the elastic fiber may be in the form of a short fiber or in the form of a long fiber. The long fiber means a fiber having a length of 50 mm or more, and includes continuous fibers. The elastic fibers are preferably in the form of continuous fibers. This is because if the elastic fiber is a continuous fiber, it is continuously stretched by hot air from the nozzle lip, so that there is an advantage that not only the fiber diameter is reduced but also the variation in the fiber diameter is reduced. Moreover, the same tendency is observed when stretching with cold air. As a result, the texture when viewed through the nonwoven fabric is improved, and the variation in the stretch properties of the nonwoven fabric is reduced. The fact that a thin fiber diameter can be obtained can reduce the capacity of hot air and cold air, which is advantageous in terms of manufacturing cost.

  When the elastic fiber contains the polyolefin-based elastomer and other resins, the content of the polyolefin-based elastomer in the elastic fiber is preferably 10 to 99% by weight, particularly 50 to 80% by weight. As the other resin, for example, a rubber or a resin made from a thermoplastic elastomer such as a styrene elastomer such as SBS, SIS, SEBS, or SEPS, a polyester elastomer, or a polyurethane elastomer can be used. These can also be used in combination of two or more.

  When the elastic fiber contains the polyolefin elastomer and other resin, the fiber form of the elastic fiber includes (a) a single fiber composed of a blend polymer of the polyolefin elastomer and another resin, and (b) The form of the composite fiber containing this polyolefin-type elastomer and other resin is mentioned. Examples of the composite fiber include a core-sheath composite fiber, a side-by-side composite fiber, and a split fiber.

  Since the above-mentioned polyolefin-based elastomer has the above-described density, the spinnability is very good even if it is melt-spun alone. Therefore, it is not necessary to improve spinnability by using other resins in combination. When other resins are used in combination, the inherent elasticity of the polyolefin-based elastomer may be impaired. That is, it is particularly preferable that the elastic fiber is composed only of the polyolefin-based elastomer as a resin component.

  From the viewpoint of enhancing the stretch properties, lowering the cost, and improving the productivity, as described above, the elastic fiber layer includes other elastic fibers different from the elastic fibers in addition to the elastic fibers containing the polyolefin-based elastomer. Fibers may be included. The other elastic fiber is not particularly limited as long as it can form a nonwoven fabric together with the elastic fiber containing the polyolefin-based elastomer. Examples of other elastic fibers include thermoplastic elastomers such as the above-mentioned different polyolefin elastomers (polyolefin elastomers mainly composed of propylene, etc.), styrene elastomers, polyester elastomers, polyurethane elastomers, and the like. An elastic fiber is mentioned. The blending ratio of the other elastic fiber with respect to the weight of the entire elastic fiber layer is preferably 5 to 80% by weight, particularly 5 to 50% by weight.

  In addition, the elastic fiber layer may contain non-elastic fibers in addition to the elastic fibers containing the polyolefin-based elastomer from the viewpoint of improving the touch and texture and increasing the strength. Or in addition to the elastic fiber containing the said polyolefin-type elastomer and the other elastic fiber different from this elastic fiber, the non-elastic fiber may be contained. Examples of the inelastic fiber include fibers made of polyethylene (PE), polypropylene (PP), polyester (PET or PBT), polyamide, and the like. Inelastic fibers may be short fibers or long fibers, and may be hydrophilic or water repellent. Moreover, a core-sheath type or side-by-side type composite fiber, a split fiber, a modified cross-section fiber, a crimped fiber, a heat-shrinkable fiber, or the like can be used. These fibers can be used alone or in combination of two or more. When the elastic fiber layer is configured to include an elastic fiber and a non-elastic fiber, the weight ratio of the former / the latter is 20/80 to 80/20, particularly 30/70 to 70/30. It is preferable from the viewpoints of having excellent stretch properties, realizing high strength, good touch, and improved texture.

  As described above, the stretchable nonwoven fabric of the present invention may be composed of only an elastic fiber layer, or a substantially inelastic nonelastic fiber layer may be laminated on at least one surface thereof. . FIG. 1 shows a schematic diagram of a cross-sectional structure in a preferred embodiment of the stretchable nonwoven fabric of the present invention. The stretchable nonwoven fabric 10 of this embodiment is configured by laminating the same or different substantially inelastic non-elastic fiber layers 2 and 3 on both surfaces of the elastic fiber layer 1.

  The elastic fiber layer 1 is an aggregate including elastic fibers. The elastic fiber layer 1 has a property that it can be stretched and contracts when released from the stretched force. The elastic fiber layer 1 preferably has a residual strain of 20% or less, particularly 10% or less when contracted after 100% elongation in at least one direction parallel to the surface. This value is preferably satisfied in at least one of the MD direction and the CD direction, and more preferably satisfied in both directions.

  The elastic fiber contained in the elastic fiber layer 1 is formed by, for example, a melt blown method in which a molten resin is extruded from a nozzle hole, and the extruded molten resin is elongated by hot air to thin the fiber, or a semi-molten resin is used. Manufactured by the spunbond method of drawing by cold air or mechanical draw ratio. Moreover, an elastic fiber can also be manufactured by the spinning blow method which is a kind of melt spinning method.

  The elastic fiber layer 1 can be in the form of a web or nonwoven fabric containing elastic fibers. For example, it may be a web or a non-woven fabric formed by a spinning blow method, a spun bond method, a melt blow method, or the like. Particularly preferred is a web obtained by the spinning blow method.

  In the spinning blown method, a pair of hot air discharge portions are arranged opposite to each other around the nozzle, and a pair of cold air discharge portions are arranged opposite to each other downstream from the nozzle in the vicinity of the tip of the molten polymer discharge nozzle. Use a spinning die. According to the spinning blow method, the stretch of the molten fiber by hot air and the cold stretch by cold air are continuously performed, so that there is an advantage that the stretchable fiber can be easily formed. Further, since the fibers do not become too dense and elastic fibers having a thickness similar to short fibers can be formed, there is an advantage that a nonwoven fabric with high air permeability can be obtained. Further, according to the spinning blow method, a continuous filament web can be obtained. The continuous filament web is extremely advantageous in the present embodiment because it is less likely to break at the time of high elongation than the short fiber web and easily develops elasticity.

  Examples of the spinning die used in the spinning blow method include those described in FIG. 1 of JP-B 43-30017, those shown in FIG. 2 of JP-A 62-90361, The thing described in FIG. 2 of 174008 gazette can be used. Furthermore, what is shown by FIG. 2 of Unexamined-Japanese-Patent No. 3-174008, and what is shown by FIG. 1 thru | or FIG. 3 of patent 3335949 can be used. The fibers spun from the spinning die are deposited on a conveyor consisting of a collection net.

  Inelastic fiber layers 2 and 3 have extensibility, but are substantially inelastic. The stretchability here refers to the case where the constituent fibers themselves are stretched, and even if the constituent fibers themselves are not stretched, the two fibers that have been heat-sealed at the intersection of the fibers are separated from each other, or the fibers are thermally fused. The three-dimensional structure formed by a plurality of fibers may be structurally changed due to wearing or the like, and the constituent fibers may be broken, and the whole fiber layer may be elongated.

  As the fibers constituting the non-elastic fiber layers 2 and 3, the same fibers as those described above as the stretchable non-elastic fibers that can be included in the elastic fiber layer 1 can be used. The inelastic fiber layers 2, 3 can be continuous filaments or short fiber webs or nonwovens. In particular, a short fiber web is preferable from the viewpoint of forming thick and bulky inelastic fiber layers 2 and 3. The two inelastic fiber layers 2 and 3 may be the same or different with respect to the material, basis weight, thickness, and the like of the constituent fibers. In the case of a core-sheath type composite fiber, the core is preferably PET or PP, and the sheath is preferably a low melting point PET, PP or PE. In particular, the use of these composite fibers is preferable in that the heat fusion with the constituent fibers of the elastic fiber layer becomes strong and the delamination hardly occurs.

  At least one of the two non-elastic fiber layers 2 and 3 is preferably 1.2 to 20 times, particularly 1.5 to 5 times as thick as the elastic fiber layer 1. On the other hand, regarding the basis weight, it is preferable that the basis weight of the elastic fiber layer is higher than the basis weight of at least one of the two inelastic fiber layers 2 and 3. In other words, the non-elastic fiber layer is preferably thicker and has a smaller basis weight than the elastic fiber layer. By having such a relationship between the thickness and the basis weight, the inelastic fiber layer becomes thicker and bulkier than the elastic fiber layer. As a result, the stretchable nonwoven fabric 10 is soft and has a good texture.

Regarding the thickness of the non-elastic fiber layers 2 and 3, it is preferably 0.05 to 5 mm, particularly preferably 0.1 to 1 mm. On the other hand, the thickness of the elastic fiber layer 1 is preferably smaller than the thickness of the non-elastic fiber layers 2 and 3, specifically 0.01 to 2 mm, particularly 0.1 to 0.5 mm. preferable. The thickness is measured by the following method after the stretchable nonwoven fabric is left unloaded for 2 days or more in an environment of 20 ± 2 ° C. and 65 ± 2% RH. An elastic nonwoven fabric is sandwiched between flat plates with a load of 0.5 cN / cm ² . Under this condition, the cross section of the stretchable nonwoven fabric is observed with a microscope at a magnification of 50 to 200 times, and the average thickness is obtained in each field of view. Let the average value of the thickness of 3 visual fields be the thickness of an elastic nonwoven fabric.

For the basis weight itself of the non-elastic fibrous layers 2 and 3, from the viewpoints of and residual strain which covers the surface of the elastic fiber layer uniform, respectively 1~60g / m ^2, to be particularly 5 to 15 g / m ² preferable. On the other hand, the basis weight itself of the elastic fiber layer 1 is preferably larger than the basis weight of the non-elastic fiber layers 2 and 3 from the viewpoint of stretch characteristics and residual strain. Specifically, it is preferably 5 to 80 g / m ² , particularly 10 to 40 g / m ² .

  Regarding the fiber diameter of the constituent fibers, the fiber diameter of the constituent fibers of the elastic fiber layer 1 is 1.2 to 5 times the fiber diameter of the constituent fibers of at least one of the non-elastic fiber layers 2 and 3, particularly 1.2 to 2.. It is preferably 5 times. In addition to this, the constituent fiber of the elastic fiber layer 1 has a fiber diameter of 5 μm or more, particularly 10 μm or more, preferably 100 μm or less, particularly 40 μm or less, from the viewpoint of air permeability and stretchability. On the other hand, the constituent fibers of the inelastic fiber layers 2 and 3 preferably have a fiber diameter of 1 to 30 μm, particularly 10 to 20 μm. That is, as the constituent fibers of the non-elastic fiber layers 2 and 3, it is preferable to use those that are thinner than the constituent fibers of the elastic fiber layer 1. Thereby, the fusion point of the constituent fibers of the non-elastic fiber layers 2 and 3 located on the surface layer is increased. The increase in the fusion point is effective in preventing the occurrence of fuzz in the stretchable nonwoven fabric 10. Furthermore, the stretchable nonwoven fabric 10 having a good touch can be obtained by using thin fibers.

  As shown in FIG. 1, the elastic fiber layer 1 and the non-elastic fiber layers 2 and 3 are bonded to the entire surface by thermal fusion of fiber intersections in a state where the constituent fibers of the elastic fiber layer 1 maintain the fiber form. ing. That is, the joining state differs from the conventional stretchable nonwoven fabric that is partially joined. In the stretchable nonwoven fabric 10 of the present embodiment in which the elastic fiber layer 1 and the non-elastic fiber layers 2 and 3 are joined together, the interface between the elastic fiber layer 1 and the non-elastic fiber layers 2 and 3 and the vicinity thereof. In FIG. 2, the intersections of the constituent fibers of the elastic fiber layer 1 and the constituent fibers of the non-elastic fiber layers 2 and 3 are heat-sealed, and are bonded substantially uniformly over the entire surface. By being bonded over the entire surface, it is possible to prevent the floating between the elastic fiber layer 1 and the non-elastic fiber layers 2 and 3, that is, the formation of a space by separating both layers. When floating occurs between the two layers, there is no sense of unity between the elastic fiber layer and the non-elastic fiber layer, and the texture of the stretchable nonwoven fabric 10 tends to decrease. According to this embodiment, a stretchable nonwoven fabric having a multi-layer structure with a sense of unity, such as a single nonwoven fabric, is provided.

  “The state in which the constituent fibers of the elastic fiber layer 1 maintain the fiber form” means that even if most of the constituent fibers of the elastic fiber layer 1 are given heat, pressure, or the like, a film or film- A state in which the fiber structure is not deformed. There exists an advantage that sufficient breathability is provided to the elastic nonwoven fabric 10 of this embodiment because the constituent fiber of the elastic fiber layer 1 is in the state of maintaining the fiber form.

  In the elastic fiber layer 1, the intersections of the constituent fibers are thermally fused in the layer. Similarly, in the inelastic fiber layers 2 and 3, the intersections of the constituent fibers are heat-sealed in the layers.

  In at least one of the two non-elastic fiber layers 2 and 3, a part of the constituent fibers are in the elastic fiber layer 1, and / or a part of the constituent fibers of the elastic fiber layer is at least one of the two. The inelastic fiber layers 2 and 3 are in a state of entering. By being in such a state, integration of the elastic fiber layer 1 and the non-elastic fiber layers 2 and 3 is promoted, and it is more effectively prevented that floating occurs between both layers. As a result, the layers are combined with each other following the surface of each layer. Part of the constituent fibers of the non-elastic fiber layer enters the elastic fiber layer 1 and remains there, or penetrates through the elastic fiber layer 1 and reaches the other non-elastic fiber layer. When the surface connecting the surface fibers in each layer is assumed macroscopically, a part of the constituent fibers of the other layer enters the cross-sectional thickness direction of the layer from this surface into the fiber space formed inside the layer. It is out. When the constituent fibers of the non-elastic fiber layer enter the elastic fiber layer 1 and remain there, it is preferable that the constituent fibers are further entangled with the constituent fibers of the elastic fiber layer 1. Similarly, when the constituent fiber of the non-elastic fiber layer penetrates through the elastic fiber layer 1 and reaches the other non-elastic fiber layer, the constituent fiber is the same as the constituent fiber of the other non-elastic fiber layer. Preferably they are entangled. This is confirmed by the fact that no space is substantially formed between the layers when the cross section in the thickness direction of the stretchable nonwoven fabric is observed with an SEM or a microscope. The term “entanglement” as used herein means a state in which fibers are sufficiently intertwined, and a state in which the fiber layers are simply overlapped is not included in the intertwining. Whether or not they are entangled, for example, after applying the air-through method without overlapping the fiber layer and heat fusion, the force required to peel the fiber layer from the state where the fiber layer is simply overlapped In comparison with the force to peel off the fiber layer, if there is a substantial difference between them, it can be determined that they are entangled.

  In order to allow the constituent fibers of the non-elastic fiber layer to enter the elastic fiber layer and / or to allow the constituent fibers of the elastic fiber layer to enter the non-elastic fiber layer, the constituent fibers of the non-elastic fiber layer and the non-elastic fiber layer It is preferable that at least one of the non-elastic fiber and the elastic fiber is in a web state (a state where the fiber is not heat-sealed) before the process of thermally fusing the constituent fibers. From the viewpoint of allowing the constituent fibers to enter other layers, the fiber layer in the web state is preferable because the short fibers have a higher degree of freedom than the long fibers.

  Further, it is preferable to use the air-through method in order to allow the constituent fibers of the non-elastic fiber layer to enter the elastic fiber layer 1 and / or to allow the constituent fibers of the elastic fiber layer to enter the non-elastic fiber layer. By using the air-through method, the constituent fibers can be made to enter the opposing fiber layer, and the constituent fibers can be easily made to enter from the opposing fiber layer. In addition, by using the air-through method, it becomes easy to allow the constituent fibers of the inelastic fiber layer to enter the elastic fiber layer 1 while maintaining the bulkiness of the inelastic fiber layer. In the case where the constituent fibers of the non-elastic fiber layer are allowed to penetrate the elastic fiber layer 1 and reach the other non-elastic fiber layer, it is preferable to use the air-through method in the same manner. In particular, it is preferable to laminate an inelastic fiber layer in a web state with the elastic fiber layer and use the air-through method. In this case, the constituent fibers of the elastic fiber layer may be heat-sealed. Furthermore, as will be described later in the production method, by performing the air-through method under specific conditions, and to improve the flow of hot air, the breathability of the stretchable nonwoven fabric, particularly the breathability of the elastic fiber layer is high. By doing, a fiber can be made to penetrate more uniformly. A method other than the air-through method, for example, a method of spraying steam can also be used. It is also possible to use a spunlace method, a needle punch method, etc., but in that case, the bulkiness of the inelastic fiber layer is impaired, or the constituent fibers of the elastic fiber layer appear on the surface. The texture of the resulting stretchable nonwoven fabric tends to decrease.

  In particular, when the constituent fibers of the non-elastic fiber layer are entangled with the constituent fibers of the elastic fiber layer 1, it is preferable that the non-elastic fiber layer is entangled only by the air-through method.

  In order to entangle the fibers by the air-through method, the gas blowing pressure, the blowing speed, the basis weight and thickness of the fiber layer, the conveying speed of the fiber layer, and the like may be appropriately adjusted. By simply adopting the conditions for producing a normal air-through nonwoven fabric, the constituent fibers of the inelastic fiber layer and the constituent fibers of the elastic fiber layer 1 cannot be entangled. As will be described later in the production method, the stretchable nonwoven fabric intended in the present invention is obtained by performing the air-through method under specific conditions.

  In the air-through method, generally, a gas heated to a predetermined temperature is penetrated in the thickness direction of the fiber layer. In that case, fiber entanglement and fiber intersection fusion occur simultaneously. However, in this embodiment, it is not essential to fuse the fiber intersections between the constituent fibers in each layer by the air-through method. In other words, in the air-through method, the constituent fibers of the non-elastic fiber layer are allowed to enter the elastic fiber layer 1 or the constituent fibers are entangled with the constituent fibers of the elastic fiber layer 1 and the non-elastic fiber layer This operation is necessary for heat-sealing the constituent fibers of the elastic fiber layer and the constituent fibers of the elastic fiber layer. The direction in which the fibers enter varies depending on the passing direction of the heated gas and the positional relationship between the inelastic fiber layer and the elastic fiber layer. The inelastic fiber layer is preferably an air-through nonwoven fabric in which fiber intersections are fused in the constituent fibers by an air-through method.

  As is apparent from the above description, in the preferred form of the stretchable nonwoven fabric of the present embodiment, the elastic fiber in a state in which the constituent fibers maintain the fiber form inside the thickness direction of the substantially inelastic inelastic air-through nonwoven fabric. Layer 1 is included, and a part of the constituent fibers of the air-through nonwoven fabric enters the elastic fiber layer 1 and / or a part of the constituent fibers of the elastic fiber layer enters the inelastic fiber layer. It has become. In a more preferred form, some of the constituent fibers of the air-through nonwoven fabric are entangled only with the constituent fibers of the elastic fiber layer 1 by the air-through method. Since the elastic fiber layer 1 is included in the air-through nonwoven fabric, the constituent fibers of the elastic fiber layer 1 are not substantially present on the surface of the stretchable nonwoven fabric. This is preferable from the point that the stickiness peculiar to an elastic fiber does not arise.

  Although not shown in FIG. 1, the stretchable nonwoven fabric 10 of the present embodiment may be embossed. Embossing is performed for the purpose of further increasing the bonding strength between the elastic fiber layer 1 and the non-elastic fiber layers 2 and 3. Therefore, if the elastic fiber layer 1 and the non-elastic fiber layers 2 and 3 can be sufficiently joined by the air-through method, it is not necessary to perform embossing. In the embossing, the constituent fibers are joined to each other. However, unlike the air-through method, the constituent fibers are not entangled depending on the embossing.

  The stretchable nonwoven fabric 10 of this embodiment has stretchability in at least one direction in the in-plane direction. It may have elasticity in all directions in the plane. In that case, it is not hindered that the degree of elasticity varies depending on the direction. With respect to the direction of expansion and contraction, the degree of elasticity is preferably 20 to 500 cN / 25 mm, particularly 40 to 150 cN / 25 mm, at 100% elongation. Further, the residual strain when contracted from the 100% stretched state is preferably 15% or less, particularly preferably 10% or less.

The stretchable nonwoven fabric 10 of this embodiment can be used for various uses such as surgical clothes and cleaning sheets from the viewpoint of its good texture, fuzz prevention, stretchability, and breathability. In particular, it is preferably used as a constituent material of absorbent articles such as sanitary napkins and disposable diapers. For example, it can be used as a sheet for providing elastic stretchability to a sheet constituting the outer surface of a disposable diaper, a waistline part, a waist part, a leg periphery part, or the like. Moreover, it can be used as a sheet or the like for forming a stretchable wing of a napkin. Moreover, even if it is another site | part, it can be used for the site | part etc. which want to provide a stretching property. The basis weight and thickness of the stretchable nonwoven fabric can be appropriately adjusted according to the specific application. For example, when used as a constituent material of an absorbent article, it is desirable that the basis weight is about ²⁰ to 160 g / m ² and the thickness is about 0.1 to 5 mm. In addition, the stretchable nonwoven fabric of the present invention is flexible and has high air permeability because the constituent fibers of the elastic fiber layer maintain the fiber form. Regarding the bending stiffness which is a measure of flexibility, the stretchable nonwoven fabric of the present invention preferably has a bending stiffness value as low as 10 cN / 30 mm or less. Regarding the air permeability, the air permeability is preferably 16 m / (kPa · s) or more. The maximum elongation in the expansion / contraction direction is desirably 100% or more.

  The bending stiffness is measured in accordance with JIS L-1096, and is obtained as an average value when bent in the flow direction and in a direction perpendicular to the flow direction, respectively, under the conditions of an indentation amount of 8 mm by a handle ohmmeter and a slit width of 10 mm. The air permeability is obtained as the reciprocal of the air resistance measured by AUTOMATIC AIR-PERMEABILITY TESTER KES-F8-AP1 manufactured by Kato Tech.

  Next, the preferable manufacturing method of the elastic nonwoven fabric 10 of this embodiment is demonstrated, referring FIG. FIG. 2 schematically shows a preferable manufacturing apparatus used in the method for manufacturing the stretchable nonwoven fabric 10 of the present embodiment. The apparatus shown in FIG. 2 includes a web forming unit 100, a hot air processing unit 200, and a stretching unit 300 in this order from the upstream side to the downstream side of the manufacturing process.

  The web forming unit 100 includes a first web forming device 21, a second web forming device 22, and a third web forming device 23. As the first web forming apparatus 21 and the third web forming apparatus 23, card machines are used. As the card machine, the same card machines as those normally used in the technical field can be used without particular limitation. On the other hand, as the second web forming device 22, a spinning blow spinning device is used. In the spinning blown spinning apparatus, a pair of hot air discharge portions are arranged opposite to each other around the nozzle near the tip of the molten polymer discharge nozzle, and a pair of cold air discharge portions downstream of the nozzle are centered on the nozzle. Opposing spinning dies are provided.

  The hot air processing unit 200 includes a hot air furnace 24. In the hot stove 24, heated gas heated to a predetermined temperature, particularly heated air is blown out. When three layers of webs stacked on top of each other are introduced into the hot stove, the heated gas is forced to penetrate from the top to the bottom of the web, in the opposite direction, or in both directions.

  The stretching unit 300 includes a weak joining device 25 and a stretching device 30. The weak joining device 25 includes a pair of embossing rolls 26 and 27. The weak joining device 25 is for ensuring the joining of the webs of the respective layers in the fiber sheet formed by the hot air processing unit 200. A stretching device 30 is disposed downstream of the weak joining device 25 and adjacent thereto. The stretching device 30 includes a pair of rolls 31 and 32. Each of the rolls 31 and 32 has tooth grooves extending in the axial direction and meshing with each other on the peripheral surface portion thereof. Therefore, in the following description, the rolls 31 and 32 are referred to as tooth gap rolls. When the tooth gap rolls 31 and 32 are rotating, the fiber sheets are supplied to and engaged with the meshing portions so that the fiber sheets are in the circumferential direction of the tooth gap rolls 31 and 32 (that is, the longitudinal direction of the sheets). ).

  When the manufacturing method of the elastic nonwoven fabric using the apparatus which has the above structure is demonstrated, first, a pair of web which consists of the same or different inelastic fiber will be distribute | arranged to each surface of the web which consists of elastic fiber. The “web made of elastic fibers” means not only a web made only of elastic fibers but also an elastic fiber layer (a layer indicated by reference numeral 1 in FIG. 1) formed from the web, as long as it does not impair the elastic elasticity. Webs containing a small amount of inelastic fibers in addition to the fibers are also included.

  As shown in FIG. 2, in the web forming unit 100, inelastic short fibers are used as a raw material, and a non-elastic fiber web 3 ′ is manufactured by a card machine that is the first web forming device 21, and continuously conveyed in one direction. Let Fibers spun by a spinning blown spinning device which is the second web forming device 22 are deposited on a conveyor made of a collection net using elastic resin made of polyolefin elastomer or the like as a raw material, and include continuous filaments of elastic fibers. An elastic fiber web 1 'is produced. This is peeled off from the conveyor and laminated on the inelastic fiber web 3 ′ formed by the first web forming device 21 and continuously conveyed in one direction. On the elastic fiber web 1 ′, an inelastic fiber web 2 ′ manufactured by a card machine which is the third web forming device 23 is further laminated.

  In addition, after the non-elastic fiber web 3 'is temporarily fused by heat treatment or after temporary entanglement, elastic fibers spun directly on the non-elastic fiber web 3' are preferably directly deposited. By doing in this way, the freedom degree of an elastic fiber becomes high and it becomes easy to mutually enter a mutual fiber with a wind etc., and it is preferable. Examples of temporary fusing by heat treatment include a heat roll method, a pressure calender roll method, a steam method, and an air-through method, and examples of temporary entanglement include a needle punch method and a water jet method. In particular, use of a heat roll and an air-through method is preferable in that the texture of the nonwoven fabric is not impaired and the facility space can be reduced. The non-elastic fiber web 3 'is preferably not wound after the temporary fusion or temporary entanglement, and the elastic fibers are preferably directly deposited on the non-elastic fiber web 3' in-line. Once wound up, the inelastic fiber web 3 'may be crushed by the winding pressure. The purpose of provisional fusion and provisional entanglement is to prevent the web from being blown away by wind or the like when the elastic fibers are directly melt spun and deposited on the web.

  When the spinning blown method is used to form the elastic fiber web 1 ', there is an advantage that the stretchable fiber can be easily formed because the melted fiber is continuously stretched by hot air and cold stretched by cold air. Further, since the fibers do not become too dense and elastic fibers having a thickness similar to short fibers can be formed, there is an advantage that a nonwoven fabric with high air permeability can be obtained. Further, according to the spinning blow method, a continuous filament web can be obtained. The continuous filament web is extremely advantageous in the present embodiment because it is less likely to break at the time of high elongation than the short fiber web and easily develops elasticity.

  When the elastic fiber web 1 'is composed of, for example, two kinds of fibers, specifically, the elastic fiber web 1' is composed of an elastic fiber containing the polyolefin-based elastomer and another elastic fiber different from the elastic fiber. In the case where it is constituted, or in the case where it is constituted by the elastic fiber containing the polyolefin-based elastomer and the non-elastic fiber, the spinning die of the spinning blown spinning device shown in FIG. 2 is the one shown in FIG. Can be used. The spinning die shown in FIG. 3 has a structure in which spinning nozzles A and spinning nozzles B are alternately arranged. From the spinning nozzle A, the resin containing the polyolefin-based elastomer is discharged. On the other hand, another thermoplastic elastomer or inelastic resin is discharged from the spinning nozzle B.

  The laminate of the three webs is sent to an air-through hot air furnace 24 where hot air treatment is performed. By the hot air treatment, the intersections of the fibers are thermally fused, and the elastic fiber web 1 'is bonded to the non-elastic fiber webs 2' and 3 'on the entire surface. In the hot air treatment, it is preferable that the webs of the respective layers are not integrated. As a result, the bulky and thick state of each web is maintained even after the hot air treatment, and an elastic nonwoven fabric having a good texture can be obtained.

  In addition to heat-sealing the intersections of the fibers and bonding the webs of each layer to the entire surface by hot air treatment, some of the constituent fibers of the non-elastic fiber web 2 ′ located mainly on the hot air blowing surface side are elastic It is preferable to let it enter into the fiber web 1 '. Further, it is preferable that a part of the constituent fibers of the non-elastic fiber web 2 ′ is caused to enter the elastic fiber web 1 ′ and further entangled with the constituent fibers of the web 1 ′ by controlling the conditions of the hot air treatment. . Alternatively, it is preferable that a part of the constituent fibers of the non-elastic fiber web 2 ′ penetrate the elastic fiber web 1 ′ to reach the non-elastic fiber web 3 ′ and entangle with the constituent fibers of the web 3 ′. .

A part of the constituent fibers of the non-elastic fiber web 2 ′ is allowed to enter the elastic fiber web 1 ′ and / or a part of the constituent fibers of the elastic fiber web 1 ′ is allowed to enter the non-elastic fiber web 2 ′. The conditions are preferably a hot air flow rate of 0.4 to 3 m / second, a temperature of 80 to 160 ° C., a conveying speed of 5 to 200 m / minute, and a heat treatment time of 0.5 to 10 seconds. Particularly preferred is a hot air flow rate of 1 to 2 m / sec. If a high air permeability net is used for the air-through heat treatment, the fibers are more likely to enter through the air. Similarly, when the elastic fiber web 1 ′ is directly spun on the non-elastic fiber web 3 ′, the constituent fibers of the elastic fiber web 1 ′ easily enter the non-elastic fiber web 3 ′ due to wind during spinning. The net used for the hot air treatment and the net used for the direct spinning of the elastic fiber have an air permeability of 250 to 800 cm ³ / (cm ² · s), particularly 400 to 750 cm ³ / (cm ² · s). preferable. The above conditions are also preferred in terms of softening the fibers and allowing them to penetrate uniformly and fusing the fibers. Furthermore, in order to entangle the fiber, it becomes possible by setting the hot air flow rate to 3 to 5 m / second and the blowing pressure to 0.1 to 0.3 kPa. When the air permeability of the elastic fiber web 1 ′ is 8 m / (kPa · s) or more, more preferably 24 m / (kPa · s) or more, the hot air can flow and the fibers can be more uniformly entrained. Therefore, it is preferable. Further, the fiber is well fused and the maximum strength is increased. In addition, fuzz is prevented.

  In the hot air treatment, a part of the constituent fibers of the non-elastic fiber web 2 ′ enters the elastic fiber web 1 ′ and at the same time, the constituent fibers of the non-elastic fiber web 2 ′ and / or the configuration of the non-elastic fiber web 3 ′. It is preferable that the fibers and the constituent fibers of the elastic fiber web 1 ′ are heat-sealed at the intersections thereof. In this case, the hot air treatment is preferably performed under conditions such that the elastic fiber after the hot air treatment maintains the fiber form. That is, it is preferable to prevent the constituent fibers of the elastic fiber web 1 'from forming a film or film-fiber structure by hot air treatment. In the hot air treatment, the constituent fibers of the inelastic fiber web 2 ′ are heat-sealed at the intersection, and similarly, the constituent fibers of the elastic fiber web 1 ′ and the constituent fibers of the inelastic fiber web 3 ′ are intersected. Heat fusion.

  The fiber sheet 10B in which the three webs are integrated is obtained by the air-through hot air treatment. The fiber sheet 10B has a long band shape having a certain width and extending in one direction. The fiber sheet 10B is then conveyed to the stretching unit 300. In the stretching unit 300, the fiber sheet 10 </ b> B is first transported to the weak joining device 25. The weak joining device 25 is composed of an embossing device provided with a metal embossing roll 26 in which embossing convex portions are regularly arranged on the peripheral surface and a metal or resin receiving roll 27 arranged opposite thereto. The fiber sheet 10B is subjected to hot embossing by the weak joining device 25. As a result, a fiber sheet 10A that has been embossed is obtained. In addition, since the web of each layer is mutually joined and integrated by the heat | fever fusion | bonding performed by the hot-air process part 200 prior to the hot embossing by the weak joining apparatus 25, the hot embossing by the weak joining apparatus 25 is this invention. Is not essential. When it is desired to ensure the joining and integration of the webs of the respective layers, the heat embossing by the weak joining device 25 is effective. Moreover, according to the weak joining apparatus 25, in addition to the web integration of each layer, there exists an advantage that the fluff of the fiber sheet 10A can be suppressed.

  The hot embossing by the weak bonding apparatus 25 is performed auxiliary to the thermal fusion performed by the hot air processing unit 200, and therefore the processing conditions may be relatively mild. Conversely, if the conditions for hot embossing are severe, the bulkiness of the fiber sheet 10A is impaired, and the fiber is formed into a film, which negatively affects the texture and breathability of the finally obtained stretch nonwoven fabric. From such a viewpoint, the linear pressure of hot embossing and the heating temperature of the embossing roll are set.

  The fiber sheet 10 </ b> A obtained by hot embossing has a large number of discrete dotted joints. The joint is formed in a regular arrangement pattern. It is preferable that the joining part is formed discontinuously, for example, in both the flow direction (MD) and the orthogonal direction (CD) of the fiber sheet 10A.

  The fiber sheet 10 </ b> A that has been subjected to the heat embossing in the weak bonding apparatus 25 is continuously sent to the stretching apparatus 30. As shown in FIG. 4, the stretching device 30 applies tension to the fiber sheet 10 </ b> A before and after the stretching process by the tooth groove rolls 31 and 32 and the slip preventing means 33 that prevents the fiber sheet 10 </ b> A to be stretched from slipping in the machine flow direction. Tension applying means 34 and 35 are provided.

  The slip prevention means 33 is composed of a roll in contact with the tooth gap roll 31. The roll is composed of a rubber roll, and the sliding and shrinkage of the fiber sheet 10 </ b> A passing between the tooth gap rolls 31 and 32 are suppressed by pressing the peripheral surface portions against the tooth gap roll 31. The anti-slip means 33 made of a roll can be arranged so as to press the peripheral surface portion against the tooth gap roll 32, and thereby the same effect as described above can be achieved.

  As another example of the slip prevention means 33 shown in FIG. 4, a suction path that opens in the peripheral surface portion is provided in one roll, and suction means that sucks the stretched fiber sheet 10A through the suction path is attached. Can also be used.

  The tension applying means 34 includes a pair of tension rolls 34 a and 34 b arranged on the upstream side of the tooth gap rolls 31 and 32. The tension applying means 35 includes a pair of tension rolls 35 a and 35 b disposed on the downstream side of the tooth gap rolls 31 and 32.

  As shown in FIG. 5, the pitch P between adjacent teeth 31a and 32a in each tooth space roll 31 and 32 is preferably 1.0 mm to 5.0 mm, and the width W of each tooth is preferably the pitch. Is less than 1/2 and the tooth height H is preferably greater than or equal to the pitch of adjacent teeth. When the form of the tooth gap in each roll is within such a range, the fiber sheet 10 </ b> A supplied between the tooth gap rolls 31 and 32 can be imparted with high stretchability that has not been conventionally provided. The pitch between adjacent teeth in the tooth gap rolls 31 and 32 refers to the distance between the center line of one tooth and the center line of an adjacent tooth. The tooth width of the tooth gap roll refers to the width of one tooth. The width of the teeth is not uniform, and a trapezoidal tooth that narrows from the root of the tooth toward the tip of the tooth may be used. The height of the teeth of the roll refers to the length from the root to the tip of the teeth.

  The pitch P between adjacent teeth in each of the tooth gap rolls 31 and 32 is more preferably 1.5 to 3.5 mm, and even more preferably 2.0 to 3.0 mm in consideration of uniform elongation of the fiber sheet 10A. . Further, the tooth width W of each of the rolls 2 and 3 is more preferably 1/4 to 1/2 of the pitch between teeth, and more preferably 1/3 to 1/2, considering the strength of the teeth. Furthermore, the tooth height H of each roll is 2.0 (1 of the pitch) when the tooth pitch is 2.0 mm, for example, in consideration of increasing the draw ratio in order to give stretchability to the fiber sheet 10A. 0.0 times) to 4.0 (2.0 times the pitch) mm, and preferably 2.5 (1.25 times the pitch) to 3.5 (1.75 times the pitch) mm.

  It is preferable to chamfer the corners of the tips of the teeth 31a and 32a in each of the tooth gap rolls 31 and 32 so that the fiber sheet 10A is not damaged by the corners of the teeth 31a and 32a. The radius of curvature of chamfering is preferably 0.1 to 0.3 mm.

  The meshing depth D of the teeth 31a and 32a of the tooth gap rolls 31 and 32 is preferably 1.0 mm or more and 2.0 mm or more in consideration of increasing the draw ratio in order to give stretchability to the fiber sheet 10A. Even more preferred. Here, the meshing depth of teeth refers to a length in which adjacent teeth overlap when the tooth gap rolls 31 and 32 are meshed and rotated.

  The tooth gap rolls 31 and 32 are engaged with each other and rotated when a driving force from a driving means (not shown) is transmitted to one of the rotation shafts. In addition to the teeth 31a and 32a, a general gear defined in JIS B1701 may be attached to each shaft of the tooth gap rolls 31 and 32 as a driving gear. As a result, the teeth 31a and 32a of the tooth gap rolls 31 and 32 are not engaged with each other, but the gears are engaged with each other so that the drive is transmitted to the tooth groove rolls 31 and 32 and the tooth groove rolls 31 and 32 are rotated. Can do. In this case, the teeth 31a and 32a of the tooth gap rolls 31 and 32 do not contact each other.

  In FIG. 6, the state of the drawing process of the fiber sheet 10 </ b> A by the drawing device 30 is schematically shown. Specifically, the fiber sheet 10 </ b> A is supplied to the meshing portion of the stretching device 30 while rotating the pair of tooth gap rolls 31 and 32. Then, as shown in FIG. 6, the fiber sheet 10 </ b> A is stretched between the tooth gap rolls 31 and 32. From the viewpoint of more effectively imparting stretchability to the fiber sheet 10A, the fiber sheet 10A is supplied between the tooth gap rolls 31 and 32 in a state where tension is applied to the fiber sheet 10A before stretching by the tension rolls 34a and 34b. It is preferable to do. The tension applied to the fiber sheet 10A to be supplied is preferably 10% to 80%, more preferably 20% to 70% of the breaking stress of the fiber sheet 10A before stretching.

  From the same viewpoint, it is preferable to apply tension to the stretched fiber sheet 10 </ b> A by the tension rolls 35 a and 35 b and pull out the sheet from between the tooth gap rolls 31 and 32. The tension applied to the fiber sheet 10A to be supplied is preferably 5% to 80% of the breaking stress of the fiber sheet 10A after the stretching process, and more preferably 10% to 70%. The breaking stress of the sheet is smaller after the processing than before the tooth gap extension processing. Further, the stretched fiber sheet 10A provided with stretchability by the tooth gap stretching process is easily stretched even with a slight tension. From such a viewpoint, it is preferable that the tension applied to the fiber sheet 10A that has been subjected to the drawing process is weaker than the tension applied to the fiber sheet 10A that has not been drawn.

  By the stretching process, the non-elastic fiber webs 2 and 3 in the fiber sheet 10 </ b> A are sufficiently stretched, and thereby the degree to which the non-elastic fiber webs 2 and 3 hinder free expansion and contraction of the elastic fiber web 1 is greatly reduced. To do. As a result, according to this production method, it is possible to efficiently produce a stretchable nonwoven fabric that is highly stretchable and has a good appearance with little tearing and fuzzing.

  By the stretching process, the thickness of the fiber sheet 10A is preferably increased 1.1 times to 4 times, particularly 1.3 times to 3 times before and after the stretching process. As a result, the fibers of the inelastic fiber layers 2 and 3 are plastically deformed and stretched to make the fibers thinner. At the same time, the non-elastic fiber layers 2 and 3 become more bulky and feel better and cushioning becomes better.

  If the thickness of the fiber sheet 10A before being stretched is thin, there is an advantage that the space for transporting and storing the roll sheet of the fiber sheet 10A can be reduced.

  Furthermore, it is preferable that the bending rigidity of the fiber sheet 10 </ b> A is changed to 30 to 80%, particularly 40 to 70% as compared with that before the drawing process by the drawing process. As a result, a soft nonwoven fabric with good drapability can be obtained. Moreover, since the bending rigidity of 10 A of fiber sheets before extending | stretching process is high, since it becomes difficult for a wrinkle to enter into fiber sheet 10A by a conveyance line, it is preferable. In addition, the fiber sheet 10A is not wrinkled even during the drawing process, and it is easy to process, which is preferable.

  The thickness and bending rigidity of the fiber sheet 10A before and after the stretching process are as follows: the elongation of the fibers used for the inelastic fiber layers 2 and 3, the embossing pattern of the embossing rolls, the pitches of the concavo-convex rolls 33 and 34, the thicknesses of the tips, It can be controlled by the total amount.

The thickness is obtained by the following method after the stretchable nonwoven fabric is left unloaded in an environment of 20 ± 2 ° C. and 65 ± 2% RH for 2 days or more. First, the elastic nonwoven fabric is sandwiched between flat plates with a load of 0.5 cN / cm ² . Under this condition, the cross section is observed at a magnification of 25 to 200 times with a microscope, and the average thickness of each layer is obtained. The total thickness is determined from the distance between the flat plates. About the penetration | invasion of a fiber, let the intermediate point of mutual penetration | invasion be thickness.

  The fiber sheet 10A sent out from the stretching device 30 is released from the stretched state in the width direction. That is, the elongation is eased. As a result, the stretchability in the longitudinal direction is expressed in the fiber sheet 10A, and the sheet 10A contracts in the longitudinal direction. Thereby, the intended stretchable nonwoven fabric 10 is obtained. When the stretched state is released, the stretched state may be completely released, or the stretched state may be released in a state where the stretched state is maintained to some extent as long as stretchability is exhibited. Good.

Next, as a specific application of the stretchable nonwoven fabric of the present invention, an example in which the nonwoven fabric is applied to a pants-type disposable diaper will be described. This pants-type disposable diaper includes an absorbent main body including an absorbent core, and an outer packaging material joined to the non-skin contact surface side of the absorbent main body, and includes an abdominal side portion and a back side portion of the outer packaging material. Both side edges are joined together to form a pair of side seals, a waist opening and a pair of leg openings. This diaper has the following characteristics.
(A) The outer packaging material has a structure in which an outer layer sheet made of a stretchable sheet and an inner layer sheet made of a non-stretchable sheet are laminated, and the outer layer sheet and the inner layer sheet have the side seal portion and the It is not joined in the whole area or most part of a part except a peripheral part of a waist opening part and the said leg opening part.
(B) The absorbent main body and the inner layer sheet of the outer packaging material are joined by a main body joining portion.
(C) In a state where the side seal portion is separated and the outer packaging material is deployed, the substantial width of the inner layer sheet is wider than the width of the outer layer sheet in a contracted state.
The pants-type disposable diaper having the above features will be described below with reference to the drawings.

  As shown in FIGS. 7 to 10, the diaper 101 includes a liquid-permeable top sheet 102, a liquid-impermeable or water-repellent back sheet 103 and a liquid-retaining absorption disposed between both sheets 102 and 103. A substantially vertically long absorbent main body 110 having a conductive core 104 and an outer packaging material 111 bonded to the back sheet 103 side (non-skin contact surface side) of the absorbent main body 110.

  The outer packaging material 111 has an hourglass shape in which both side edges are bound inward in the central portion in the longitudinal direction, and defines the outline of the diaper. The outer packaging material 111 is divided in the longitudinal direction into an abdominal side A disposed on the wearer's abdomen, a back side B disposed on the dorsal side, and a crotch C positioned therebetween. The abdominal side portion A and the back side portion B correspond to the longitudinal front and rear end portions of the outer packaging material 111, and the crotch portion C corresponds to the longitudinal center portion of the outer packaging material 111. In the outer packaging material 111, both side edges A1 and A2 of the ventral side A and both side edges B1 and B2 of the back side B are joined together, and the disposable diaper 101 has a waist opening 105 and a pair of leg openings. 106 is formed. By this joining, a pair of side seal portions S, S are formed on the left and right side edges of the disposable diaper 101 to form a pants shape. For these bondings, for example, heat sealing, high frequency sealing, ultrasonic sealing, or the like is used.

  The top sheet 102, the back sheet 103, and the absorbent core 104 are each rectangular, and are integrated to form a vertically long absorbent main body 110. As the top sheet 102, the back sheet 103, and the absorbent core 104, the same ones that are conventionally used in this type of diaper can be used. For example, the absorbent core 104 may be made of superabsorbent polymer particles and fiber material and covered with tissue paper (not shown).

  As shown in FIG. 11, the absorbent core 104 includes an hourglass-shaped central absorber 141 and a pair of side absorbers 142 and 142 provided symmetrically on both sides of the central absorber 141. The central absorbent body 141 and the pair of side absorbent bodies 142, 142 are separated from each other at least at the crotch portion. One side in the longitudinal direction and the other side in the longitudinal direction of the side absorbent body 142 are connected to each other at one side in the longitudinal direction (abdominal side) and the other side in the longitudinal direction (back side) of the central absorbent body 141, respectively. Therefore, the cut-out portions 143 and 143 are formed between the central absorbent body 141 and the pair of side absorbent bodies 142 and 142, respectively.

  One part in the longitudinal direction, the central part in the longitudinal direction, and the other part in the longitudinal direction are each region when the absorbent core 104 is divided into three regions so as to be divided into approximately three equal parts in the longitudinal direction. When the absorptive core 104 has the separation part 143, the both-sides edge part of the absorptive core 104 will stand up easily. Further, when the absorbent core 104 is pressed in the width direction, the entire width of the absorbent core 104 is narrowed, so that the shrinkage in the width direction of the outer packaging material 111 is difficult to be inhibited. The shape of the absorbent core 104 in plan view is not limited to the shape shown in FIG. 11. For example, the side absorbent body 142 is connected to the central absorbent body 141 only in one of the longitudinal direction one part or the longitudinal direction other part. The shape, the shape in which the side absorbent body 142 is not connected to the central absorbent body 141 (separated), or the shape that does not have the separating portion 143 may be used (not shown).

  As shown in FIGS. 8 to 10, side cuffs 108 and 108 made of a liquid-resistant or water-repellent and breathable material are formed on both the left and right sides of the absorbent main body 110 in the longitudinal direction. . In the vicinity of the free end of each side cuff 108, a side cuff elastic member 181 is disposed in an extended state. Accordingly, when the disposable diaper 101 assembled as shown in FIG. 7 is worn, the side cuffs 108 stand up by contraction of the side cuff elastic members 181, and the liquid in the width direction of the absorbent main body 110. Is prevented from flowing out. As shown in FIGS. 9 and 10, the sheet material 182 for forming the side cuffs 108, 108 has a predetermined width portion 182 </ b> S outside the width direction of the absorbent main body 110 in the diaper state. It is wound down to the skin contact surface side and fixed between the absorbent core 104 and the back sheet 103.

  The outer packaging material 111 has a structure in which an outer layer sheet 112 made of the stretchable nonwoven fabric of the present invention and an inner layer sheet 113 made of a non-stretchable sheet are laminated. The outer layer sheet 112 forms the outer surface of the diaper, and the inner layer sheet 113 is disposed on the inner surface side of the outer layer sheet 112. The stretchable nonwoven fabric that forms the outer layer sheet 112 only needs to have stretchability in at least the diaper width direction (left-right direction in FIG. 8) when the diaper is in an unfolded state. The non-stretchable sheet forming the inner layer sheet 113 does not have stretchability at least in the diaper width direction when the diaper is in an unfolded state.

  The outer layer sheet 112 can extend more in the diaper width direction than in the diaper longitudinal direction (vertical direction in FIG. 8). More specifically, in the diaper width direction, it stretches greatly and contracts after stretching (maximum elongation of 100% or more and elongation recovery rate of 70% or more), but in the diaper longitudinal direction, it stretches only slightly (for example, , Maximum elongation of 50% or less).

  As the non-stretch sheet, a nonwoven fabric, a laminated material of a nonwoven fabric and a resin film, a porous film, and the like are preferable. The non-stretch sheet is preferably formed from a nonwoven fabric made of thermoplastic fibers from the viewpoint of improving air permeability and texture, and is formed from a water-repellent nonwoven fabric from the viewpoint of preventing excrement leakage. Are preferred.

  In the diaper 101, as shown in FIG.9 and FIG.10, between the outer layer sheet | seat 112 and the inner layer sheet | seat 113 in each of the abdominal side part A and the back side part B in side seal part A1, A2, B1, B2. Are bonded to each other by heat sealing, high frequency sealing or ultrasonic sealing, and an adhesive such as a hot melt adhesive is used at the peripheral edge 150 of the waist opening 105 and the peripheral edge 160 of each of the pair of leg openings 106. 152 and 162 are joined together. And between the outer layer sheet | seat 112 and the inner layer sheet | seat 113 in each of the ventral | abdominal part A and the back | dorsal part B is not joined in most of the parts except these parts.

  Specifically, between the outer layer sheet 112 and the inner layer sheet 113, in addition to the side seal portions A1, A2, B1, and B2, the peripheral edge portion 150 of the waist opening portion 105, and the peripheral edge portions 160 of the pair of leg opening portions 106, respectively. And it is joined in the diaper width direction center part of each of the abdominal part A and the back part B, and it is not joined in parts other than those.

  In this way, in a wide range in the ventral side A and the back side B, a configuration in which the outer layer sheet 112 and the inner layer sheet 113 are not joined together minimizes a portion where the outer packaging material 111 is hardened by the adhesive. The portion of the outer surface of the diaper and the inner surface of the outer packaging material 111 that is not covered with the absorbent main body 110 can be made soft and soft to the touch. Moreover, since the air permeability of the outer packaging material 111 is maintained well, it is possible to provide a diaper that is less likely to be stuffy. Further, since the outer peripheral sheet 112 and the inner layer sheet 113 are joined to each other at the peripheral edge portions 150 and 160 of the waist opening 105 and the pair of leg openings 106, a stretchable outer packaging material 111 is provided at the waistline portion. Therefore, moderate fit can be obtained.

  A plurality of waist elastic members 151 and 151 are arranged along the opening peripheral edge of the waist opening 105 on the peripheral edge 150 of the waist opening 105 in each of the ventral side A and the back side B. These waist elastic members 151 and 151 are fixed in an extended state between the outer layer sheet 112 and the inner layer sheet 113 via an adhesive 152.

  In addition, leg elastic members 161a and 161b are also provided along the peripheral edge of each opening on the peripheral edge 160 and 160 of the leg opening extending over the ventral side A, the crotch C and the back side B. It is arranged. These leg elastic members 161 a and 161 b are fixed in an extended state between the outer layer sheet 112 and the inner layer sheet 113 via an adhesive 162. As the waist elastic member 151 and the leg elastic members 161a and 161b, elastic materials such as natural rubber, polyurethane resin, urethane foam resin, and hot melt elastic member are made into a thread shape (thread rubber) or a belt shape (flat surface), respectively. Those formed into (rubber) are preferably used.

  In this way, thread-like or belt-like elastic members 151, 161a, 161b are sandwiched between the outer layer sheet 112 and the inner layer sheet 113 at the peripheral edge portions 150, 160 of the waist opening 105 and the pair of leg openings 106, respectively. By fixing to the state, the fit of these parts can be enhanced without being restricted by the expansion / contraction characteristics of the outer packaging material 111.

  In addition, since the thread-like or belt-like elastic members 151, 161a, 161b can be fixed in a state of being sandwiched between the outer layer sheet 112 and the inner layer sheet 113, such an elastic member is fixed to an outer packaging material made of a single sheet. Compared to the case, the elastic member can also prevent the wearer from feeling uncomfortable or deteriorating the appearance.

  In the diaper 101, the width of the region where the outer layer sheet 112 and the inner layer sheet 113 are joined at the peripheral edge 150 of the waist opening 105 is the width of the waist opening for each of the ventral side A and the back side B. It is preferably within 70 mm from the peripheral edges 105a and 105b, and more preferably within 60 mm. The width of the region where the outer layer sheet 112 and the inner layer sheet 113 are joined to each other at the peripheral edge 160 of the leg opening 106 is the leg opening at each of the ventral side A, the crotch C and the back side B. It is preferably within 50 mm from the peripheral edge of 106, and more preferably within 30 mm.

  In addition, in the diaper width direction in each of the ventral side A and the back side B, the total length (L1 + L2) of the portion where the outer layer sheet 112 and the inner layer sheet 113 are not joined is determined by the left and right side seal parts A1, The length La (Lb) between A2 is preferably 60% or more, more preferably 70% or more, and further preferably 75% or more.

  The area of the portion where the outer layer sheet 112 and the inner layer sheet 113 are not joined to each other in the ventral side A and the back side B is 60 to 100 with respect to the areas of the ventral side A and the back side B, respectively. %, And more preferably 70 to 100%. Those satisfying this numerical value are referred to as “whole area or most part”.

  As shown in FIG. 8, the dimensions and ratios of the respective parts described in the present specification are in a natural state (external force such as tension is applied) with the diaper in an unfolded state and the contraction force by the elastic members of the waist opening and the leg opening is released. The value measured in the state of not acting) or based on it.

  In the diaper 101, between the outer layer sheet 112 and the inner layer sheet 113 in the crotch part C, the peripheral part 160 of the leg opening part and the diaper width direction center part of the crotch part C via the adhesive 162 and the joint part 114 Although it is joined, it is not joined in other parts. In the diaper 101, as shown in FIG. 8, a leg elastic member 161 for imparting stretchability to the peripheral edge 160 of the leg opening extends from the peripheral edge 160 of the leg opening to the center of the crotch C in the width direction. The portion where the leg elastic member 161 for imparting stretchability to the leg opening in the circumferential direction is arranged in this manner is included in the peripheral edge 160 of the leg opening.

  In the diaper 101, the outer layer sheet 112 and the inner layer sheet 113 are joined to each other at the center part in the diaper width direction of the abdominal part A, the back part B, and the crotch part C. The inside appearance can be further improved. Further, when a disposal tape (not shown) is provided on the outer surface of the outer packaging material 111, the disposal tape can be firmly fixed by fixing the disposal tape to the central part in the diaper width direction. The disposal tape is a tape that holds the diaper in a rolled state, and various conventionally known tapes can be used.

  Since the outer layer sheet 112 and the inner layer sheet 113 are joined to each other in the center part of the diaper width direction of the abdominal part A, the back side part B, and the crotch part C, the back sheet 103 has patterns, characters, and other symbols. When such a design is provided, the design can be clearly seen from the outer surface side of the diaper.

  In the diaper 101, as shown in FIGS. 8 and 9, the outer layer sheet 112 constituting the outer surface side of the outer packaging material 111 sandwiches and fixes the waist elastic members 151 and 51 by the outer layer sheet 112 and the inner layer sheet 113. The portions 112a and 112b of the outer layer sheet 112 extending from the inner layer sheet 113 are folded back to the absorbent main body 110 side. As for the absorptive main body 110, the skin contact surface side in the longitudinal direction both ends is covered with the folded-back portions (folded portions) 112a and 112b of the outer layer sheet 112. The folded portions 112a and 112b of the outer layer sheet 112 have portions that overlap with both ends in the longitudinal direction of the absorbent main body 110 bonded to each other through an adhesive (not shown) over substantially the entire width of the absorbent main body 110, Thereby, the longitudinal direction both ends of the absorptive main body 110 are fixed to the outer packaging material 111. By forming the folded portions 112a and 112b, the front and rear ends of the absorbent main body 110 are prevented from coming into direct contact with the wearer, and the water absorbent polymer of the absorbent core 104 from the front and rear ends of the absorbent main body 110 is prevented. Leakage can be prevented.

  As shown in FIG. 9 and FIG. 10, the absorbent main body 110 is bonded to the inner layer sheet 113 of the outer packaging material 111 by the main body bonding portion 115 only in the central portion in the width direction, as shown in FIGS. 9 and 10. . Since the expansion and contraction of the outer packaging material 111 is less likely to be hindered by the joining of the absorbent main body 110, good fit is obtained at the waistline portion. The width W1 of the joint portion 114 between the outer layer sheet 112 and the inner layer sheet 113 in the central portion of the outer packaging material 111 in the diaper width direction is equal to the width W of the absorbent main body 110 in each of the ventral portion A and the back portion B. It is preferably 0 to 40%, and more preferably 0 to 30%. When the width W1 of the joint 114 exceeds 40% of the width W of the absorbent main body 110, the stretchability is inhibited.

  The main body bonding portion 115 is provided at a central portion in the diaper width direction. The width W2 of the main body bonding portion 115 is preferably 70% or more of the width W on the non-skin contact surface side of the absorbent main body 110 in each of the ventral side A and the back side B, and is 75% or more. More preferably. When the width W2 of the main body bonding portion 115 is 70% or more of the width W of the absorbent main body 110, the absorbent main body 110 is hardly peeled or broken during mounting. The main body joint 115 may be spaced apart in the diaper width direction.

  In a state where the side seal portion S is separated and the outer packaging material 111 is deployed, the substantial width of the inner layer sheet 113 is wider than the width of the outer layer sheet 112 in a contracted state. That is, in the state where the outer packaging material 111 is unfolded, the outer layer sheet 112 is in a contracted state due to its contraction force, but the inner layer sheet 113 is made of a non-stretchable sheet, so that the width is hardly reduced. Therefore, the inner layer sheet 113 is loosened in the width direction with respect to the outer layer sheet 112. Such a slackened inner layer sheet 113 is virtually separated from the outer layer sheet 112, and the width of the inner layer sheet 113 when the slackness of the inner layer sheet 113 is eliminated is defined as “substantial width of the inner layer sheet 113”.

  The substantial width of the inner layer sheet 113 is preferably 1.3 to 4.0 times, more preferably 1.5 to 3.0 times the width of the outer layer sheet 112 in a contracted state.

  In the diaper 101 configured in this manner, in a state where the side seal portion S is separated and the outer packaging material 111 is deployed, the substantial width of the inner layer sheet 113 is larger than the width of the outer layer sheet 112 in a contracted state. It is getting wider. Therefore, since the outer layer sheet 112 of the outer packaging material 111 is formed from an elastic sheet, the appearance and fit of the diaper when worn are good. Further, since the inner layer sheet 113 of the outer packaging material 111 is formed from a non-stretchable sheet, even if the outer packaging material 111 extends in the width direction at the time of use, the inner layer sheet 113 loosens and the absorbent main body 110 from the outer packaging material 111 Problems such as peeling off and tearing of the outer packaging material 111 hardly occur. Further, the skin contact surface side of the outer packaging material 111 has a good tactile sensation and a texture, and is excellent in softness.

  In the diaper 101, since the outer layer sheet 112 made of the stretchable nonwoven fabric of the present invention and the inner layer sheet 113 made of a non-stretchable sheet are hardly adhered, without being affected by the non-stretchable absorbent main body 110, The outer packaging material 111 has good stretchability. Even when the outer layer sheet 112 of the outer packaging material 111 is released from the stretched state, the absorbent main body 110 is excellent in appearance without contracting, and the absorbent performance of the absorbent main body 110 can be maintained. Therefore, even if the width W2 of the main body joint 115 is set wide, the stretchability in the width direction of the outer packaging material 111 is not hindered.

  As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to the said embodiment. For example, the stretchable nonwoven fabric of the present invention only needs to contain elastic fibers containing a polyolefin-based elastomer and other elastic fibers and / or non-elastic fibers different from the elastic fibers when viewed as the whole nonwoven fabric. Therefore, for example, a stretchable nonwoven fabric having two elastic fiber layers is within the scope of the present invention. In this case, one elastic fiber layer includes an elastic fiber containing a polyolefin-based elastomer, or non-elastic fibers in addition to the elastic fiber, and the other elastic fiber layer is different from an elastic fiber containing a polyolefin-based elastomer. Elastic fibers, or non-elastic fibers in addition to the elastic fibers. In addition to having two elastic fiber layers, this nonwoven fabric may have one or more inelastic fiber layers. Furthermore, an elastic nonwoven fabric having an elastic fiber layer composed only of fibers containing a polyolefin-based elastomer and one or more inelastic fiber layers is also within the scope of the present invention.

  Further, the stretchable nonwoven fabric 10 of the above embodiment has a configuration in which the same or different, substantially inelastic non-elastic fiber layers 2 and 3 are laminated on both surfaces of the elastic fiber layer 1, Instead, a two-layer structure in which an inelastic fiber layer is laminated on one surface of the elastic fiber layer may be used. Or the form of the single layer structure which consists only of an elastic fiber layer may be sufficient. About the detail of the elastic nonwoven fabric of the form of these single layer or two-layer structure, the description regarding the elastic nonwoven fabric 10 of the said embodiment which concerns on a three-layer structure is applied suitably. In addition, when using a stretchable nonwoven fabric with a two-layer structure as a constituent material of an absorbent article, especially when used on a part that touches the user's skin, the non-elastic fiber layer is used to face the wearer's skin side. It is preferable from the viewpoints of touch and prevention of stickiness.

  Moreover, when the nonwoven fabric of this invention is a structure formed by arranging an inelastic fiber layer on at least one surface of an elastic fiber layer, the structure of an elastic fiber layer and an inelastic fiber layer is not restrict | limited to what is shown in FIG.

  Moreover, in the said manufacturing method, although 10 A of fiber sheets were extended | stretched to the longitudinal direction, it can replace with this and can be extended to the width direction.

  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 stretchable nonwoven fabric shown in FIG. 1 was manufactured using the apparatus shown in FIG. First, short fibers (core: PET, sheath: PE) having a diameter of 17 μm and a fiber length of 51 mm were supplied to a card machine to form an inelastic fiber web 3 ′ made of a card web. The basis weight of the web 3 ′ was 10 g / m ² . An elastic fiber web 1 'was laminated on the non-elastic fiber web 3'.

The elastic fiber web 1 ′ was formed by the following method. As the polyolefin-based elastic resin mainly composed of ethylene, a polyolefin-based elastomer having an ethylene content of 75% by weight and a 1-butene content of 25% by weight was used. This polyolefin-based elastomer was polymerized using a metallocene catalyst. As another elastic resin different from this, SEBS resin having a styrene content of 15% by weight, a weight average molecular weight of 100,000 and MFR of 30 g / 10 min (230 ° C., 2.16 kg) was used. These resins were melted by using different extruders, the melted resins were extruded from a spinning nozzle at a die temperature of 290 ° C., and an elastic fiber web 1 ′ was formed on the net by a spinning blow method. The spinning nozzle was a side-by-side type, and a composite fiber composed of the two kinds of resins was spun. The weight ratio of the polyolefin-based elastomer to the SEBS resin in the elastic fiber was 50/50. The fiber diameter of the elastic fiber was 25 μm. The basis weight of the fiber web 1 ′ was 40 g / m ² .

On the elastic fiber web 1 ′, a non-elastic fiber web 2 ′ made of the same short fibers as described above was laminated. The basis weight of the web 2 ′ was 10 g / m ² .

  The laminate of these three-layer webs was introduced into a heat treatment machine, and hot air was blown by an air-through method to perform heat treatment. The heat treatment conditions were an on-net temperature of 140 ° C., a hot air flow rate of 2 m / second, a spraying pressure of 10 kPa, and a spraying time of 15 seconds. By this heat treatment, a fiber sheet 10B in which three layers of webs were integrated was obtained.

  Next, hot embossing was applied to the fiber sheet 10B. The hot embossing was performed using an embossing device provided with an embossed convex roll and a flat metal roll. As the embossed convex roll, a dot-shaped convex roll having a large number of convex portions having an MD pitch of 2 mm and a CD pitch of 2 mm was used. The temperature of each roll was 120 ° C., and the linear pressure was 300 N / cm. By this embossing, a fiber sheet 10A in which the joints were formed in a regular pattern was obtained.

The fiber sheet 10A was stretched. The stretching process was performed using a stretching device including a pair of tooth groove rolls having tooth grooves extending in the axial direction and meshing with each other on the peripheral surface portion. The pitch of the tooth gap roll was 2 mm, the meshing depth of the teeth was 2.5 mm, and the fiber sheet 10A was stretched in the MD at a stretch ratio of 3.5 times. As a result, a nonwoven fabric having a basis weight of 60 g / m ² that expands and contracts to MD was obtained. In addition, the conveyance speed of each process was 10 m / min.

[Example 2]
The elastic fiber web 1 ′ was formed by the following method. As a polyolefin-based elastic resin mainly composed of ethylene, a polyolefin-based elastomer having an ethylene content of 88% by weight and a 1-butene content of 12% by weight was used. This polyolefin-based elastomer was polymerized using a metallocene catalyst. As another inelastic resin different from this, a polypropylene resin (homo) of MFR 60 g / 10 min (230 ° C., 2.16 kg) was used. Using these resins, an elastic fiber web made of mixed fibers of two kinds of resins was molded. For forming the web 1 ', two extruders were used, and each resin was melted with each extruder at a die temperature of 290 ° C, extruded from a spinning nozzle, and fibers were deposited on the net by a spinning blow method. As shown in FIG. 3, the spinning nozzle had a shape that extrudes each resin alternately. The weight ratio of polyolefin elastomer to polypropylene was 50/50. The fiber diameter of the elastic fiber was 25 μm. The fiber diameter of the inelastic fiber was 18 μm. The basis weight of the web 1 ′ was 40 g / m ² .

  This web was introduced into a heat treatment machine, and hot air was blown by an air-through method to perform heat treatment. The heat treatment conditions were an on-net temperature of 140 ° C., a hot air flow rate of 2 m / second, a spraying pressure of 10 kPa, and a spraying time of 15 seconds. By this heat treatment, a fiber sheet 10B in which two kinds of fiber webs were integrated was obtained.

  Next, hot embossing was applied to the fiber sheet 10B. The hot embossing was performed using an embossing device provided with an embossed convex roll and a flat metal roll. As the embossed convex roll, a dot-shaped convex roll having a large number of convex portions having an MD pitch of 2 mm and a CD pitch of 2 mm was used. The temperature of each roll was 130 ° C., and the linear pressure was 300 N / cm. By this embossing, a fiber sheet 10A in which the joints were formed in a regular pattern was obtained.

The fiber sheet 10A was stretched. The stretching process was performed using a stretching device including a pair of tooth groove rolls having tooth grooves extending in the axial direction and meshing with each other on the peripheral surface portion. The pitch of the tooth gap roll was 2 mm, the meshing depth of the teeth was 2.5 mm, and the fiber sheet 10A was stretched in the MD at a stretch ratio of 3.5 times. As a result, a nonwoven fabric having a basis weight of 40 g / m ² that expands and contracts to MD was obtained. In addition, the conveyance speed of each process was 10 m / min.

[Comparative Example 1]
An SEBS resin having a styrene content of 15% by weight, a weight average molecular weight of 100,000 and MFR30 was used as the elastic resin. Using this elastic resin, an elastic fiber web was molded at a die temperature of 290 ° C. The diameter of the elastic fiber was 32 μm. A stretchable nonwoven fabric was prepared in the same manner as in Example 1 except for these.

[Evaluation]
The properties of the stretchable nonwoven fabric obtained in the examples and comparative examples are shown in Table 1 below. The measurement method for each item in the table is as follows.

<Bending rigidity>
Measurement was performed using HOM-3 manufactured by Daiei Scientific Instruments.

<Maximum strength, maximum elongation, strength at 100% elongation, residual strain>
A rectangular test piece having a size of 50 mm in the stretching direction of the stretchable nonwoven fabric and 25 mm in the direction perpendicular thereto was cut out. The test piece was attached to Orientec Tensilon RTC1210A. The distance between chucks was 25 mm. The test piece was stretched at a speed of 300 mm / min in the stretching direction of the nonwoven fabric, and the load at that time was measured. The load at the maximum point at that time was defined as the maximum strength. Moreover, when the length of the test piece at that time was set to B and the length of the original test piece was set to A, {(BA) / A} * 100 was made into the maximum elongation (%). Further, a 100% elongation cycle test was performed, and the strength at 100% elongation was determined from the load at 100% elongation. Furthermore, after 100% elongation, the ratio of the length that did not return when returning to the origin at the same speed was measured, and the value was taken as the residual strain. The maximum strength was also measured for the fiber sheet A, which is the raw fabric of the stretchable nonwoven fabric, by the same method.

<Feel>
The surface of the stretchable nonwoven fabric was directly touched with the palm of the hand, and the touch was determined according to the following criteria. There is a feeling of resistance (feels rough): x, there is a little resistance: Δ, there is no resistance, there is a little smooth feeling: ○, there is no resistance, there is a smooth feeling: ◎. Judgment was made by three people, and if two or more people had the same opinion, the opinion was taken as the judgment result, and if the three people were different opinions, the middle opinion was taken as the judgment result.

<Jointness between elastic fiber layer and non-elastic fiber layer>
The state when peeled by hand so as to peel between the elastic fiber layer and the non-elastic fiber layer was determined according to the following criteria. Easily peels off: x, feels a little resistant: Δ, part of the layer does not peel and part remains in the other layer: ○, part of the layer does not peel off and most remains in the other layer: ◎. Judgment was made by three people, and if two or more people had the same opinion, the opinion was taken, and if three people were different opinions, the middle opinion was taken as the judgment result.

  As is clear from the results shown in Table 1, the non-woven fabric of the example has higher strength than the non-woven fabric of the comparative example, while maintaining the maximum elongation and residual strain at the same level as the non-woven fabric of the comparative example. Further, it can be seen that the bonding property between the elastic fiber layer and the non-elastic fiber layer is good. When a disposable diaper was prepared using the nonwoven fabric of the example for the exterior, this diaper was soft to the touch, highly breathable, easy to stretch enough to be stretched, and had the characteristics that it was difficult to stick rubber marks because it was tightened over the entire surface. .

  In addition, when the cross section of the nonwoven fabric of an Example was observed by SEM, the constituent fiber of the elastic fiber layer and the constituent fiber of the non-elastic fiber layer were heat-sealed in any nonwoven fabric, and these fiber layers were joined together. It was. Moreover, it was confirmed that some of the constituent fibers of the non-elastic fiber layer have entered the thickness direction of the elastic fiber layer. The constituent fibers of the elastic fiber layer maintained the fiber form.

Drawing 1 is a mimetic diagram showing the section structure of one embodiment of the elastic nonwoven fabric of the present invention. FIG. 2 is a schematic view showing a preferred apparatus used for producing the stretchable nonwoven fabric shown in FIG. FIG. 3 is a schematic diagram showing an example of the structure of a spinning die of a spinning blown spinning device which is a second web forming device in the device shown in FIG. FIG. 4 is a perspective view showing a main part of the stretching apparatus in the apparatus shown in FIG. FIG. 5 is an enlarged view showing a main part of the tooth gap roll in the stretching apparatus shown in FIG. 4. FIG. 6 is a schematic diagram illustrating a state in which the sheet is stretched by the tooth gap roll in the stretching apparatus illustrated in FIG. 4. FIG. 7: is a perspective view which shows one Embodiment of the underpants type disposable diaper provided with the elastic nonwoven fabric of this invention. FIG. 8 is a plan view showing a developed state of the disposable diaper shown in FIG. 7. FIG. 9 is an exploded perspective view of the disposable diaper shown in FIG. 10 is a cross-sectional view taken along line XX in FIG. FIG. 11 is a plan view showing an absorbent core in the disposable diaper shown in FIG. 7.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Elastic fiber layer 2 Inelastic fiber layer 3 Inelastic fiber layer 4 Joining part 10A Fiber sheet 10 Elastic nonwoven fabric

Claims (6)

An elastic fiber containing a polyolefin-based elastomer mainly composed of ethylene, and another elastic fiber or non-elastic fiber different from the elastic fiber,
The polyolefin elastomer is a stretchable nonwoven fabric having a density of 0.855 to 0.895 g / cm ³ .   The stretchable nonwoven fabric according to claim 1, wherein the polyolefin-based elastomer is polymerized using a metallocene catalyst.   The stretchable nonwoven fabric according to claim 1 or 2, wherein the polyolefin-based elastomer has a heat value of fusion of 10 to 80 mJ / mg.   The stretchable nonwoven fabric according to any one of claims 1 to 3, wherein the polyolefin elastomer has a melt flow rate (MFR) of 2 to 350 g / 10 min.   The stretchable nonwoven fabric according to any one of claims 1 to 4, wherein the elastic fiber containing the polyolefin elastomer comprises only the polyolefin elastomer, or contains the polyolefin elastomer and another thermoplastic elastomer. . An elastic fiber layer containing the elastic fiber containing the olefin-based elastomer, and another elastic fiber and / or the non-elastic fiber different from the elastic fiber,
The stretchable nonwoven fabric according to any one of claims 1 to 5, wherein a substantially inelastic nonelastic fiber layer is disposed on at least one surface of the elastic fiber layer.

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