JP4845587B2 - Elastic nonwoven fabric - Google Patents

Description

  The present invention relates to a stretchable nonwoven fabric.

  Various stretchable nonwoven fabrics containing elastic fibers made of an elastomer resin are known. For example, U.S. Patent No. 6,057,049 describes an elastomeric nonwoven fabric comprising microfibers comprising an extrudable elastomeric composition comprising at least about 10% by weight ABA block copolymer and polyolefin. However, since the microfiber contains polyolefin as a constituent resin, the microfiber does not have sufficient expansion and contraction characteristics.

  Patent Document 2 describes a composite elastic material having an anisotropic elastic fiber web having an elastomer meltblown fiber layer and an elastomer filament layer, and a gatherable layer bonded to the web. The material constituting the elastomer filament is 40 to 80% by weight of elastomer polymer and 5 to 40% by weight of 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.

  Patent Document 3 discloses an elastic composite sheet having an elastic sheet made of a fiber or film containing 60 to 98% by weight of a styrene elastomer having a styrene content of 10 to 40% by weight and a number average molecular weight of 70,000 to 150,000. Are listed. In addition to the styrene elastomer, the fiber or film contains materials other than the elastomer, such as an olefin resin and an oil component. Due to the inclusion of these materials, the stretchable composite sheet does not have sufficient stretch properties.

JP 62-84143 A Japanese Patent Laid-Open No. 5-27043 JP 2002-361766 A

  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 elastic fibers containing a styrenic elastomer, and other elastic fibers and / or non-elastic fibers different from the elastic fibers,
The object resin of the elastic fiber containing the styrene-based elastomer is to provide a stretchable nonwoven fabric having a melt viscosity of 100 to 700 Pa · s at 230 ° C. and a melt tension of 0.2 to 2.0 cN. Is achieved.

  The stretchable nonwoven fabric of the present invention has higher stretch properties than conventional stretchable nonwoven fabrics. In particular, since it is easy to reduce the fiber diameter of the constituent fibers and to form continuous fibers, the stretchability can be further enhanced thereby. Furthermore, since it is easy to form an elastic fiber only from an elastomer resin without containing other resin components and oil components, the stretchability can be further enhanced thereby. Moreover, when an inelastic fiber layer is laminated | stacked on the elastic fiber layer, joining of both layers becomes favorable and delamination does not occur easily.

  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 / or inelastic 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 styrenic elastomer. The elastic fiber contained in the elastic fiber layer is only the elastic fiber containing the styrenic elastomer or the elastic fiber and another elastic fiber different from the elastic fiber.

  The elastic fiber containing the styrenic elastomer is composed only of the styrenic elastomer, or contains the styrenic elastomer and one or more other resins.

  The elastic fiber containing the styrenic elastomer used in the present invention is characterized by the melt viscosity and melt tension of the constituent resin. The constituent resin of the elastic fiber containing the styrene elastomer has a melt viscosity of 100 to 700 Pa · s at 230 ° C. The constituent resin of the elastic fiber containing the styrenic elastomer has a melt tension of 0.2 to 2.0 cN. The melt viscosity in this range is at a low level compared to the melt viscosity of a conventionally used styrenic elastomer, and the melt tension in this range is compared to the melt tension of a conventionally used styrene elastomer. Is at a high level. That is, the constituent resin of the elastic fiber containing the styrenic elastomer used in the present invention is characterized by having a low melt viscosity and a high melt tension. By using an elastic fiber made of a constituent resin having such characteristics, the stretchable nonwoven fabric of the present invention has higher stretchability compared to the conventional one.

  In particular, the constituent resin of the elastic fiber containing the styrenic elastomer has a low melt viscosity and a high melt tension, which makes it difficult for yarn breakage to occur when melt spinning the elastic fiber, and easily makes a continuous fiber having a small diameter. Can be manufactured. The ability to make the elastic fiber small in diameter greatly contributes to the unevenness of the texture of the nonwoven fabric, and greatly contributes to the improvement of the stretch properties. The fact that elastic fibers can be made into continuous fibers (filaments) also greatly contributes to the improvement of stretch properties. The continuous fiber is substantially continuous and means, for example, a fiber having a length of 10 cm or more.

  Furthermore, since the constituent resin of the elastic fiber containing the styrenic elastomer has a low melt viscosity and a high melt tension, a shot due to yarn breakage is less likely to occur. 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 melt viscosity of the constituent resin of the elastic fiber containing the styrenic elastomer is 200 to 700 Pa · s, particularly 300 to 600 Pa · s, the stretchability is further improved. A similar effect can be obtained by setting the melt tension of the styrene elastomer to 0.2 to 1.5 cN, particularly 0.5 to 1.5 cN.

The melt viscosity and melt tension of the constituent resin of the elastic fiber containing the styrenic elastomer are measured using a capillograph (manufactured by Toyo Seiki). The measurement conditions are as follows. The cylinder diameter of the barrel is 10 mm and the piston diameter is 9.55 mm. The diameter of the die nozzle hole is 1.0 mm. Keep the barrel at 230 ° C., and fill the resin pellets with a stick while putting the resin pellets in the cylinder little by little so as not to enter bubbles. After filling the resin, hold for about 5 minutes until the resin temperature stabilizes. The melt viscosity is measured at the viscosity stability point at a piston speed of 5 mm / min. The shear rate at this time is 60 sec ⁻¹ . The melt tension is obtained by measuring the tension at a piston speed of 15 mm / min and a draw speed of 15 m / min at the same temperature. The measurement result was an average value of N = 3.

  A melt index (ASTM D1238, 190 ° C., 2.16 kg), which is a general index in the technical field, can also be adopted as a viscosity index when the resin constituting the elastic fiber is melted. When the melt index is preferably 4 to 50 g / 10 min, more preferably 6 to 20 g / 10 min, the temperature of the extruder set to a temperature lower than the normal molding temperature (for example, 50 to 100 ° C. lower than the molding temperature). In the range, the extruder resin pressure during molding can be kept low. The melt index is merely a viscosity index at a specific temperature, and the viscosity of the resin decreases as the temperature is raised, and the degree of decrease varies depending on the resin. For this reason, the melt index is a measure of good moldability, but it does not always apply in all cases.

  The styrenic elastomer contained in the elastic fiber has a glass transition temperature Tg of −40 to −15 ° C., particularly −30 to −20 ° C. It is preferable from the viewpoint of suppressing the feeling of stickiness.

  The styrenic elastomer preferably has an inflection point temperature of 200 to 250 ° C, particularly 215 to 250 ° C, as determined by differential scanning calorimetry (DSC). This is because the bond strength at the physical cross-linking points (in the case of styrene-based elastomers, styrene blocks) becomes weak at a relatively low temperature, so that the decrease in viscosity increases when the temperature is raised.

  The glass transition point temperature and the inflection point temperature by DSC of the styrene elastomer are both determined by DSC measurement. Measurement conditions can be determined by heating a sample of 3 to 5 mg in a nitrogen atmosphere and heating from −60 ° C. at a heating rate of 10 ° C./min.

  There are no particular restrictions on the type of styrenic elastomer as long as the above physical properties are satisfied. For example, (1) those containing styrene, ethylene and butylene as monomer components (for example, main chain skeleton is SEBS), (2) those containing styrene, ethylene and propylene (for example, main chain skeleton is SEPS), (3) styrene and butylene (For example, the main chain skeleton is SBS), (4) those containing styrene and isoprene (for example, the main chain skeleton is SIS), and the like. Among these, (1) those containing styrene, ethylene and butylene, (2) those containing styrene, ethylene and propylene, or both (1) and (2) are used to easily satisfy the above-mentioned physical properties. Since a styrene-type elastomer is obtained, it is preferable.

  The styrene elastomers (1) and (2) preferably have a weight average molecular weight of 30,000 to 200,000, particularly 50,000 to 150,000.

  As described above, the elastic fiber containing the styrenic elastomer may be composed of only the styrenic elastomer as a resin component, or the styrenic elastomer and one or more other resins. It may contain and may be comprised. When the elastic fiber contains the styrenic elastomer and other resins, the content of the styrenic elastomer in the elastic fiber is preferably 20 to 99% by weight, particularly 50 to 80% by weight. When the elastic fiber containing the styrenic elastomer is composed only of the styrenic elastomer, the melt viscosity and melt tension described above are the same as the melt viscosity and melt tension of the styrenic elastomer itself.

  When the elastic fiber contains the styrene-based elastomer and other resin, as the other resin, for example, rubber or thermoplastic elastomer such as polyolefin-based elastomer, polyester-based elastomer, polyurethane-based elastomer, or the like may be used. it can. Further, a resin other than the thermoplastic elastomer, for example, a thermoplastic resin such as polyethylene or polypropylene can be used. These can also be used in combination of two or more.

  When the elastic fiber contains the styrene elastomer and other resin, the fiber form of the elastic fiber includes (a) a single fiber comprising a blend polymer of the styrene elastomer and another resin, and (b) The form of the composite fiber containing this styrene-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.

  The above styrenic elastomer has very good spinnability even when melt-spun alone. On the other hand, since the conventional styrene elastomer has low spinnability by itself, the spinnability has been improved by using other resins in combination. However, the stretch property inherently possessed by the styrene-based elastomer has been impaired accordingly. Therefore, the above-mentioned styrenic elastomer that can be melt-spun alone is extremely advantageous from the viewpoint that the inherent stretchability is not impaired. That is, it is particularly preferable that the elastic fiber is composed only of the styrene-based elastomer as a resin component.

  Conventionally, attempts have been made to fiberize by adding an oil component such as paraffin oil in order to lower the melt viscosity of the styrene-based elastomer. The oil component may bleed out on the surface of the fiber, which may result in a decrease in fusibility with other resins. On the other hand, it is not necessary to add an oil component to the styrene elastomer. An elastic fiber that does not contain an oil component has a high fusing property between elastic fibers and a fusing property with non-elastic fibers. As a result, in the embodiment shown in FIG. 1 to be described later, the elastic fiber layer 1 and the non-elastic fiber layers 2 and 3 are joined well, and delamination hardly occurs. Further, fuzz on the surface of the stretchable nonwoven fabric 10 is also suppressed. Furthermore, since no oil component is contained, the generation of volatile components is reduced during the melt spinning of elastic fibers, and the environmental load is reduced. From these viewpoints, it is preferable that the elastic fiber containing the styrenic elastomer in the present invention does not substantially contain an oil component. “Substantially not containing” does not mean that no oil component is contained, and it means that an oil component inevitably mixed during the production of the elastic fiber is allowed.

  The elastic fiber may be in any form of long fiber and short 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.

  As described above, in addition to the elastic fiber containing the styrene-based elastomer described above, the elastic fiber layer has other elasticity different from that of the elastic fiber in terms of enhancing the stretch property, reducing the cost, and increasing the productivity. 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 styrene elastomer. Examples of the other elastic fibers include elastic fibers containing thermoplastic elastomers such as styrene elastomers, polyolefin elastomers, polyester elastomers, polyurethane elastomers, and the like, which are different from the above-mentioned styrene elastomers. The blending ratio of the other elastic fiber with respect to the weight of the entire elastic fiber is preferably 5 to 80% by weight, particularly 10 to 50% by weight.

  In addition, the elastic fiber layer may contain non-elastic fibers in addition to the elastic fibers containing the styrene-based elastomer, in terms of improving the touch and texture, and increasing the strength. Alternatively, in addition to the elastic fiber containing the styrenic elastomer and other elastic fiber different from the elastic fiber, non-elastic fiber may be included. 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 also 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 pinning 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 disposed opposite to each other around the nozzle, and a pair of cold air discharge portions are disposed opposite to each other downstream from the 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 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 was measured by the following method after leaving the stretchable nonwoven fabric in an environment of 20 ± 2 ° C. and 65 ± 2% RH under no load for 2 days or more. An elastic nonwoven fabric is sandwiched between flat plates at a load of 0.5 cN / cm ^{2, and} the cross section is observed with a microscope at a magnification of 25 to 200 times under the state, and an average thickness is obtained for each field of view. It can be obtained as an average value of the thickness of the visual field.

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.

  In the stretchable nonwoven fabric 10 of this embodiment, as shown in FIG. 1, minute recesses are formed in the inelastic fiber layers 2 and 3. Thereby, the cross section of the stretchable nonwoven fabric 10 has a waveform shape microscopically. This waveform shape is generated by stretching 10 stretchable nonwoven fabrics, as will be described later in the manufacturing method. This corrugated shape does not have a significant adverse effect on the texture of the nonwoven fabric 10 itself. Rather, it is advantageous in that a softer and better nonwoven fabric can be obtained.

  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 elongation is preferably 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. As the spinning die used in the spinning blow method, for example, the one shown in FIG. 2 of JP-A-3-174008 or the one shown in FIGS. 1 to 4 of Japanese Patent No. 3335949 can be used.

  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 concave and convex rolls 33 and 34 in which large-diameter portions 31 and 32 and small-diameter portions (not shown) are alternately formed in the axial direction and can be engaged with each other. . When the fiber sheet is caught between both the uneven rolls 33 and 34, the fiber sheet is stretched in the axial direction of the roll (that is, the width direction of the sheet).

  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 as the second web forming device 22 are deposited on a conveyor made of a collection net, and contain continuous filaments of elastic fibers, using an elastic resin made of styrene-based elastomer or the like as a raw material. 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 confounding 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 made of an elastic fiber containing the styrenic 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 styrenic elastomer and the non-elastic fiber, the spinning die of the spinning blown spinning device 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 styrene-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 conveyance speed of 5 to 200 m / minute, and a heat treatment time of 0.5 to 10 seconds. In particular, it is preferably higher than the amount of hot air generally used as the air-through method, and particularly preferably the amount of hot air is 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 webs of the respective layers are joined and integrated by heat fusion performed by the hot air processing unit 200 prior to the hot embossing by the weak joining device 25, the hot embossing by the weak joining device 25 is performed according to the present 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.

  Since the hot embossing by the weak joining apparatus 25 is performed in an auxiliary manner to the heat fusion performed by the hot air processing unit 200, 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 a fiber film is formed, which negatively affects the texture and breathability of the finally obtained stretchable nonwoven fabric. From such a viewpoint, the linear pressure of hot embossing and the heating temperature of the embossing roll are set.

  As shown in FIG. 4, the fiber sheet 10 </ b> A obtained by the hot embossing has a large number of discrete dotted joints 4. The joint 4 is formed in a regular arrangement pattern. It is preferable that the joining part 4 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 FIGS. 2 to 5, the fiber sheet 10 </ b> A is drawn with a pair of concave and convex rolls 33 and 34 in which large-diameter portions 31 and 32 and small-diameter portions (not shown) are alternately formed in the axial direction. The apparatus 30 is stretched in a direction (CD) orthogonal to the transport direction (MD).

  The stretching device 30 is configured such that the pivotal support portions of one or both of the concave and convex rolls 33 and 34 are displaced up and down by a known lifting mechanism so that the distance between them can be adjusted. As shown in FIG. 1 and FIGS. 5 (b) and 5 (d), each concavo-convex roll 33, 34 has a large diameter portion 31 between one concavo-convex roll 33 and a large diameter portion 32 between the other concavo-convex roll 34. The large-diameter portion 32 of the other concave-convex roll 34 is assembled so as to be loosely inserted between the large-diameter portions 31 of the one concave-convex roll 33. The fiber sheet 10A is bitten between the rolls 33 and 34 in this state, and the fiber sheet 10A is stretched.

In this stretching step, as shown in FIGS. 4 and 5, the position of the joint portion 4 in the width direction of the fiber sheet 10 </ b> A and the positions of the large diameter portions 31 and 32 of the uneven rolls 33 and 34 are matched. Is preferred. Specifically, as shown in FIG. 4, the fiber sheet 10 </ b> A is formed with a plurality of rows of joint portions in which a plurality of joint portions 4 are formed in a straight line along the MD (see FIG. 4). FIG. 4 shows 10 rows), and in FIG. 4, one of the concave and convex portions is included in each of the joint portions 4 included in every other joint portion row R ₁ including the joint portion row R ₁ located on the leftmost side. position of the large diameter portion 31 of the roll 33 do not match, including the junction sequence R ₂ of the second from the left, for the joint portions included in each of the joint row R ₂ of every other therefrom, the other The position of the large diameter portion 32 of the uneven roll 34 is made to coincide. In FIG. 4, the range indicated by reference numerals 31 and 32 is the same as the peripheral surfaces of the large-diameter portions 31 and 32 of each roll at one point in a state where the fiber sheet 10 </ b> A is engaged between the two uneven rolls 33 and 34. The overlapping range is shown.

  When the fiber sheet 10A passes between the rolls 33 and 34 in a state of being bitten between the concave and convex rolls 33 and 34, as shown in FIGS. 5B and 5D, While the large-diameter portions 31 and 32 of any of the concave and convex rolls overlap, the region between the large-diameter portions that do not overlap with the large-diameter portions 31 and 32, that is, the region between the joint row R described above is positive in the width direction. To be stretched. Therefore, it is possible to efficiently stretch the portion other than the joint portion of the fiber sheet 10A while preventing the joint portion 4 from being broken and the webs of each layer from being peeled off. Further, by this stretching, the non-elastic fiber webs 2 and 3 are sufficiently stretched, whereby 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. 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 the 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 was determined by the following method after the stretchable nonwoven fabric was left unloaded for 2 days or more in an environment of 20 ± 2 ° C. and 65 ± 2% RH. The stretchable nonwoven fabric was sandwiched between flat plates with a load of 0.5 cN / cm ^{2, and} the cross section was observed with a microscope at a magnification of 25 to 200 times under that condition, and the average thickness of each layer was determined. The total thickness was determined from the distance between the flat plates. Regarding the fiber penetration, the midpoint of mutual penetration was defined as the thickness.

  It is preferable that the peripheral surfaces of the large-diameter portions 31 and 32 of the uneven rolls 33 and 34 are not sharp so as not to damage the fiber sheet 10A. For example, as shown in FIGS. 5B and 5D, a flat surface having a predetermined width is preferable. The width W (see FIG. 5B) of the tip surfaces of the large diameter portions 31 and 32 is preferably 0.3 to 1 mm, and is 0.7 to 2 times the dimension of the joint portion 4 in the CD direction, in particular. It is preferably 0.9 to 1.3 times. Thereby, the fiber form of inelastic fiber becomes difficult to be destroyed, and a high-strength stretchable nonwoven fabric is obtained.

The pitch P between the large diameter portions (see FIG. 5B) is preferably 0.7 to 2.5 mm. The pitch P is preferably 1.2 to 5 times, particularly 2 to 3 times, the dimension of the joint portion 4 in the CD direction. As a result, a stretchable nonwoven fabric having a cloth-like appearance and a good touch can be obtained. The pitch of the CD direction of the joint 4 (junction sequence R ₁ together intervals adjacent in the CD direction or the joint row R ₂ distance between adjacent in the CD direction) is the pitch P between the large-diameter portion On the other hand, in order to match the positional relationship, it is basically doubled, but if the fiber sheet 10A is in the range of 1.6 times to 2.4 times due to elongation in the CD direction and neck-in, the positions are matched. It is possible.

  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 fiber sheet 10A exhibits elasticity and the sheet 10A contracts in the width 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.

  The present invention is not limited to the embodiment. For example, the stretchable nonwoven fabric of the present invention only needs to contain elastic fibers containing a styrene-based elastomer and other elastic fibers and / or inelastic 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 styrenic elastomer, or an inelastic fiber in addition to the elastic fiber, and the other elastic fiber layer is different from the elastic fiber containing a styrenic 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, a stretchable nonwoven fabric having an elastic fiber layer composed only of fibers containing a styrene-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.

  Further, in the method shown in FIG. 5, the fiber sheet 10 </ b> A is stretched without being sandwiched between the large diameter portion of one uneven roll and the small diameter portion of the other uneven roll. And it can also extend | stretch in the state which pinched | interposed the fiber sheet 10A between both. That is, it can be stretched in a state of bottoming through the fiber sheet. In addition, the stretching step can be performed by the method described in JP-A-6-133998.

  Moreover, in the said manufacturing method, although 10 A of fiber sheets were extended | stretched in CD direction, it can replace with this and can be extended in MD 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]
An elastic fiber web was formed by the following method. As a resin used for the elastic fiber, SEBS having a melt viscosity of 300 Pa · s at 230 ° C. and a melt tension of 1.3 cN was used. In addition, as another inelastic fiber 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 by the respective extruders 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 SEBS 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 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 in which a web containing two kinds of fibers was integrated was obtained.

  The fiber sheet was then heat embossed. 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 in which the joints were formed in a regular pattern was obtained.

The fiber sheet was stretched. The stretching process was performed using a stretching apparatus including a pair of concave and convex rolls in which a large diameter portion and a small diameter portion were alternately formed in the axial length direction. The pitch P between the large diameter portions was 1.0 mm. The fiber sheet was drawn into CD by a drawing process. As a result, a nonwoven fabric having a basis weight of 40 g / m ² that expands and contracts to CD was obtained. In addition, the conveyance speed of each process was 10 m / min.

[Example 2]
As a resin used for the elastic fiber, SEBS having a melt viscosity of 600 Pa · s at 230 ° C. and a melt tension of 0.2 cN was used. A stretchable nonwoven fabric was prepared in the same manner as in Example 1 except for this. The fiber diameter of the elastic fiber was 30 μm. The fiber diameter of the inelastic fiber was 18 μm. The basis weight of the elastic fiber web was 40 g / m ² .

Example 3
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 resin used for the elastic fiber, SEBS (first SEBS) having a melt viscosity of 300 Pa · s at 230 ° C. and a melt tension of 1.3 cN was used. Further, as another elastic fiber resin, SEBS (second SEBS) having a melt viscosity of 1500 Pa · s at 230 ° C. and a melt tension of 1.0 cN was used. Using these resins, an elastic fiber web 1 ′ composed 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 the first SEBS and the second SEBS was 80/20. The fiber diameter of the elastic fiber made of the first SEBS was 25 μm. The fiber diameter of the elastic fiber made of the second SEBS was 35 μm. The basis weight of the web 1 ′ was 20 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 heat treatment was performed by blowing hot air using an air-through method. 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 apparatus including a pair of concave and convex rolls in which a large diameter portion and a small diameter portion were alternately formed in the axial length direction. The pitch P between the large diameter portions was 1.0 mm. The fiber sheet 10A was drawn into a CD by a drawing process. As a result, a nonwoven fabric having a basis weight of 40 g / m ² that expands and contracts to CD was obtained. In addition, the conveyance speed of each process was 10 m / min.

[Comparative Example 1]
As a resin used for the elastic fiber, an SEBS resin having a melt viscosity of 870 Pa · s at 230 ° C. and a melt tension of 0.2 cN was used. In addition, as another inelastic fiber resin different from this, a polypropylene resin (homo) of MFR 60 g / 10 min (230 ° C., 2.16 kg) was used. When the weight ratio of SEBS and polypropylene was set to 50/50 and the elastic fiber web 1 ′ was formed by the spinning blow method at a die temperature of 290 ° C. as in Example 1, the fiber was thick and uniform in terms of texture. Was not obtained. Therefore, the die temperature was raised to 320 ° C. and molding was performed again. As a result, the fiber diameter of the elastic fiber in the obtained web 1 ′ was 32 μm. The fiber diameter of the inelastic fiber was 15 μm. The basis weight of the web 1 ′ was 40 g / m ² . A stretchable nonwoven fabric was prepared in the same manner as in Example 1 except for these. In molding at a die temperature of 320 ° C., odor due to resin decomposition occurred due to the high molding temperature.

[Comparative Example 2]
As a resin used for the elastic fiber, a SEBS resin having a melt viscosity of 200 Pa · s at 230 ° C. and a melt tension of 0.1 cN was used. In addition, as another inelastic fiber resin different from this, a polypropylene resin (homo) of MFR 60 g / 10 min (230 ° C., 2.16 kg) was used. Using these resins, the elastic fiber web 1 ′ was formed by the spinning blow method at a die temperature of 290 ° C. in the same manner as in Example 1. As a result, the fiber web could not be formed due to the tearing of the elastic fibers, and a stretchable nonwoven fabric was not obtained. .

[Comparative Example 3]
As a resin used for the elastic fiber, an SEBS resin having a melt viscosity of 1500 Pa · s at 230 ° C. and a melt tension of 1.0 cN was used. In addition, as another inelastic fiber resin different from this, a polypropylene resin (homo) of MFR 60 g / 10 min (230 ° C., 2.16 kg) was used. Using these resins, the elastic fiber web 1 ′ was molded by the spinning blow method at a die temperature of 290 ° C. in the same manner as in Example 1. As a result, the elastic fibers did not become thin, the texture was not uniform, and the elasticity was not good. A nonwoven fabric could not be obtained. Even when the die temperature was increased to 320 ° C., the elastic fiber was not thinned, the texture was not good and the fabric was not uniform, and a stretchable nonwoven fabric could not be obtained.

[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.

<Strength, elongation and 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. Further, 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 defined as the residual strain.

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

  As is apparent from the results shown in Tables 1 and 2, the nonwoven fabric of the example has better stretch properties than the nonwoven fabric of the comparative example.

  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 plan view showing an example of a fiber sheet to be stretched. 5A is a cross-sectional view taken along the line aa in the CD direction of the fiber sheet shown in FIG. 4, and FIG. 5B is a diagram of a deformed state (stretched state) between the concavo-convex rolls. Sectional drawing corresponding to (a), FIG.5 (c) is sectional drawing in alignment with the cc line of CD direction of the fiber sheet shown in FIG.4, FIG.5 (d) is the state deform | transformed between the uneven | corrugated rolls ( It is sectional drawing equivalent to FIG.5 (c) of the state extended | stretched.

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 (5)

Including elastic fibers and non-elastic fibers containing a styrenic elastomer,
The styrenic elastomer contains styrene, ethylene and butylene as the monomer component, or contains styrene, ethylene and propylene, or both.
The styrene-based elastomer has a weight average molecular weight of 30,000 to 200,000,
The resin constituting the elastic fibers containing styrene elastomer, Ri and melt tension 0.2~2.0cN der in 100~700Pa · s at the melt viscosity 230 ° C.,
The inelastic fibers are polyethylene, or a fiber made of polypropylene or polyester, or Der Ru stretchable nonwoven those containing the fibers one or more.   2. The stretchable nonwoven fabric according to claim 1, wherein the styrene-based elastomer has a glass transition temperature Tg of −40 to −15 ° C. and an inflection point temperature of 200 to 250 ° C. by differential scanning calorimetry (DSC). The stretchable nonwoven fabric according to claim 1 or 2, wherein the elastic fiber does not contain an oil component .   The stretchable nonwoven fabric according to any one of claims 1 to 3, wherein the elastic fiber containing the styrene elastomer comprises only the styrene elastomer or contains the styrene elastomer and other thermoplastic elastomers. . An elastic fiber layer containing the elastic textiles containing the styrene-based elastomer,
The stretchable nonwoven fabric according to any one of claims 1 to 4 , wherein a non -elastic fiber layer containing the non-elastic fiber is disposed on at least one surface of the elastic fiber layer.

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