JP2012001856A - Nonwoven fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide nonwoven fabric which is bulky and compatibly realizes strength and touch feeling even if heat-fusible conjugate fibers are mixed.SOLUTION: A nonwoven fabric 10 comprises a first fiber made of a thermally extensible fiber that contains two components having different melting points and extends in its length when heated and a second fiber made of a heat-fusible conjugate fiber that contains two components with different melting points, where intersections of the fibers are heat-fused. The melting point of the component with a lower melting point of the heat extensible fiber is lower than the melting point of the component with a lower melting point of the heat-fusible conjugate fiber, and the difference between those melting points is 1.5 to 10°C.

Description

  The present invention relates to a nonwoven fabric and a method for producing the same. The nonwoven fabric of the present invention is particularly preferably used as a constituent material of absorbent articles such as sanitary napkins and disposable diapers.

  Regarding a nonwoven fabric made of heat-extensible fiber, which is a fiber whose length is increased by heating, the present applicant has previously described a heat-fusible composite fiber composed of two components having different melting points, and a non-heat-fusible fiber. An intersection of the heat-fusible conjugate fibers is heat-sealed, and the heat-fusible conjugate fiber and the non-heat-fusible fiber are non-heat-bonded nonwoven fabrics, As a raw material of the conductive composite fiber, a material using a heat-extensible fiber having a resin orientation index in a specific range has been proposed (see Patent Document 1).

  Separately from this, regarding the nonwoven fabric made of heat-extensible fibers, the present applicant has a number of pressure-bonded portions to which the constituent fibers are pressure-bonded or bonded, and the constituent fibers in portions other than the pressure-bonded portions. Also proposed is a three-dimensional shaped non-woven fabric in which the intersecting points are joined by means other than pressure bonding, and the pressure bonding part is a concave part and the concave part is a convex part between at least one side. (See Patent Document 2). This nonwoven fabric has the advantage that it has a three-dimensional uneven shape, is flexible, and has a low basis weight, without using a special manufacturing method, by using heat-extensible fibers as a raw material.

  As a result of further investigations on the nonwoven fabric made from heat-extensible fibers, when only the heat-extensible fibers are used as a raw material, a bulky nonwoven fabric can be easily obtained. From the viewpoint of improving the bulk recovery property in the thickness direction, it has been found that when a nonwoven fabric is produced by blending non-heat-extensible heat-fusible conjugate fibers, it is difficult to obtain a bulky nonwoven fabric. Patent Document 2 describes a combination example of a heat-fusible fiber and a heat-fusible fiber having polyethylene terephthalate having a large melting point difference between a low-melting-point component of the heat-extensible fiber and a patent document. No. 1 describes an embodiment in which a heat-extensible fiber and a fiber that does not exhibit heat-fusibility are used in combination, but in those cases, it is difficult to achieve both strength and texture.

  In addition, regarding the method for producing a nonwoven fabric using heat-extensible fibers as a raw material, the present applicant previously proposed a method for producing a nonwoven fabric through a plurality of heat treatment steps at different temperatures using a heat-extensible composite fiber (patent) Reference 3). However, since the temperature of the first heat treatment step is equal to or higher than the melting point of the low-melting-point component of the heat-extensible fiber, the extension of the heat-extensible fiber is inhibited by the fusion of the fibers. Therefore, it is disadvantageous from the viewpoint of obtaining a bulky nonwoven fabric.

JP-A-2005-350835 JP 2005-350836 A JP 2008-101285 A

  Accordingly, an object of the present invention is a non-woven fabric made of heat-extensible fibers, which is a mixture of heat-extensible fibers and heat-fusible composite fibers, in order to eliminate the disadvantages of the prior art described above. Even if it exists, it is providing the nonwoven fabric with which the nonwoven fabric is bulky and is excellent in the bulk recovery property when thickness reduces by the load added to the thickness direction of the nonwoven fabric, and it is easy to make a balance | strength and a texture.

  The present invention includes a first fiber made of a heat-extensible fiber containing two components having different melting points and extending in length by heating, and a heat-fusible conjugate fiber containing two components having different melting points. A low-melting-point component of the heat-extensible fiber is lower than the melting point of the low-melting-point component of the heat-fusible composite fiber. The present invention provides a nonwoven fabric having a melting point difference of 1.5 to 10 ° C.

  Moreover, this invention is a manufacturing method of the nonwoven fabric of Claim 1, Comprising: The heat-fusibility which contains 2 components from which melting | fusing point differs, the heat | fever extensible fiber which the length expands by heating, and 2 components from which melting | fusing point differs A first stage of blowing hot air to a fiber web containing a composite fiber by an air-through method to obtain a nonwoven fabric precursor by stretching the thermally extensible fiber, and blowing the hot air to the nonwoven fabric precursor by an air-through method, Including a second stage in which a non-woven fabric is obtained by heat-sealing the intersection of the heat-extensible fiber and the heat-fusible composite fiber, and the temperature of the hot air blown in the first stage is set to the melting point of the low-melting-point component of the heat-extensible fiber The temperature of the hot air blown in the second stage is set to a temperature lower than that of the hot air in the first stage.

  According to the present invention, even if the nonwoven fabric is made from heat-extensible fibers, and the nonwoven fabric is a mixture of heat-extensible fibers and heat-fusible composite fibers, the nonwoven fabric is bulky and excellent in strength and the like. A non-woven fabric is provided.

Fig.1 (a) is a perspective view which shows one Embodiment of the nonwoven fabric of this invention, FIG.1 (b) expands a part of cross section along the thickness direction of the nonwoven fabric shown to Fig.1 (a). It is an expanded sectional view shown. FIG. 2 is a schematic view showing an apparatus suitably used for carrying out one embodiment of the production method of the present invention. FIG. 3 is a schematic view showing an apparatus suitably used for carrying out another embodiment of the production method of the present invention. FIG. 4 is a schematic view showing an apparatus suitably used for carrying out still another embodiment of the production method of the present invention.

Hereinafter, the present invention will be described based on preferred embodiments thereof.
FIG. 1 shows a nonwoven fabric 10 which is an embodiment of the nonwoven fabric of the present invention. The nonwoven fabric 10 shown in FIG. 1 has a single layer structure. The nonwoven fabric 10 has a concavo-convex surface 10b having a concavo-convex shape on one side, and the other surface is flat or a flat surface 10a having a smaller degree of concavo-convexity than the concavo-convex surface 10b. A concave portion 18 and a convex portion 19 are formed on the uneven surface 10b. The recess 18 includes a first linear recess 18a extending in parallel with each other and a second linear recess 18b extending in parallel with each other. The convex portion 19 is formed in a region sandwiched between the concave portions 18, more specifically, in a rhombic closed region surrounded by the concave portion 18. The inside of the convex portion 19 is filled with the constituent fibers of the nonwoven fabric 10. Moreover, in the convex part 19, the constituent fiber of the nonwoven fabric 10 is melt | fused in those intersections. In the recess 18, the constituent fibers of the nonwoven fabric 10 are heat-sealed by heat embossing or the like.

  The non-woven fabric of the present invention includes, as constituent fibers, (a) a first fiber made of a heat-extensible fiber, which is a fiber that includes two components having different melting points, and whose length is increased by heating, and (b) a melting point. It is characterized by including a second fiber made from a heat-fusible composite fiber containing two different components.

Examples of the heat-extensible fiber as the raw material for the first fiber include a fiber that elongates by changing the crystalline state of the resin by heating. Particularly preferably used heat-extensible fibers include a high melting point component and a low melting point component having a melting point lower than the melting point of the high melting point component, and the low melting point component continuously extends at least part of the fiber surface in the length direction. An existing composite fiber (hereinafter, this fiber is referred to as a “heat-extensible composite fiber”). The high melting point component in the heat extensible composite fiber is a component that expresses the heat extensibility of the fiber, and the low melting point component is a component that expresses the heat fusibility. The heat-extensible conjugate fiber is stretched by performing heat treatment at least at a temperature higher than the melting point of the low melting point component and lower than the melting point of the high melting point component, but stretches at a temperature lower than the melting point of the low melting point component. It is preferable to start.
In general, in the production of nonwoven fabrics, heat-extensible fibers are obtained by performing heat treatment at a temperature not lower than the melting point of the low melting point component (second resin component described later) and not higher than the melting point of the high melting point component (first resin component described later). The nonwoven fabric using is a nonwoven fabric in a state where the heat-extensible fibers are stretched. Moreover, when this nonwoven fabric is heated at a temperature equal to or higher than the heat treatment temperature and equal to or lower than the melting point of the high melting point component, the heat stretchable fiber is further stretched.
As the form of the heat-extensible composite fiber, there are various forms such as a core-sheath type and a side-by-side type, and any form can be used, but the core part has a high melting point component and the sheath part has a low melting point component. A core-sheath type (which may be either a concentric type or an eccentric type) is preferable. In the production of the nonwoven fabric of the present invention, the heat-extensible fibers are elongated by heat treatment to produce first fibers.

  The heat-fusible conjugate fiber as the raw material of the second fiber includes a high melting point component and a low melting point component having a melting point lower than the melting point of the high melting point component, and the low melting point component has a length of at least a part of the fiber surface. It is a composite fiber that exists continuously in the direction. As the form of the heat-fusible conjugate fiber, there are various forms such as a core-sheath type and a side-by-side type, and any form can be used, but the core part has a high melting point component and the sheath part has a low melting point. A core-sheath type composed of components (which may be either a concentric type or an eccentric type) is preferred. The heat-fusible conjugate fiber may be a non-heat-extensible fiber whose length is not substantially extended by heating, or is a heat-extensible fiber whose length is extended by heating. The heat extensible fiber used for the raw material may be a fiber having a low melting point component and a different melting point. The heat-fusible conjugate fiber preferably used includes two components having different melting points and is subjected to a stretching treatment. This heat-fusible conjugate fiber does not substantially extend its length even when heat is applied. The heat-fusible conjugate fiber is stretched at the raw material stage (that is, before being used for the nonwoven fabric). The stretching treatment referred to here is a stretching operation with a stretching ratio of about 2 to 6 times.

  As described above, the first fiber is made of a heat-extensible fiber as a raw material, and the heat-extensible fiber is composed of a fiber that is elongated by application of heat. When the non-heat-extensible heat-fusible conjugate fiber whose length does not substantially extend by heating is used as a raw material for the second fiber, the heat-fusible conjugate fiber is used before and after heat application. There is no substantial change. In addition, when the second fiber uses, as a raw material, a heat-extensible fiber (provided that the melting point of the low-melting point component is different from that of the heat-extensible fiber used for the first fiber), the heat The extensible fiber is comprised from the fiber extended | stretched by provision of heat.

In the nonwoven fabric of the present invention, the melting point of the low melting point component of the heat-extensible fiber that is the raw material of the first fiber is lower than the melting point of the low melting point component of the heat-fusible composite fiber that is the raw material of the second fiber. The difference is 1.5 to 10 ° C.
Before the low melting point component of the heat-fusible conjugate fiber melts and the fibers melt together, because the melting point of the low melting point component of the heat-extensible fiber is lower than the melting point of the low melting point component of the heat-fusible conjugate fiber In addition, the heat-extensible fiber can be sufficiently heat-extended. As a result, it is possible to prevent or reduce the expansion of the heat-extensible fibers by the adhesive force generated by melting the heat-fusible conjugate fibers and the heat-extensible fibers and the heat-fusible conjugate fibers. Easy to get.
In addition, when the difference in melting point between the low melting point components is within 10 ° C., the low melting point component of the heat-fusible composite fiber is melted at a temperature not excessively higher than the melting point of the low melting point component of the heat-extensible fiber. It is possible to prevent or reduce the deterioration of the texture of the nonwoven fabric due to excessive melting of the heat-extensible fibers and the decrease in strength of the nonwoven fabric due to melting of the high melting point component of the heat-extensible fibers. That is, after the heat-extensible fiber is sufficiently stretched by heating, the low-melting point component of the heat-stretched fiber and the heat-fusible composite fiber can be melted to sufficiently heat-bond the intersection of the fibers. Thereby, the nonwoven fabric which is bulky and excellent in texture and strength can be obtained. From the viewpoint of obtaining such an effect, the difference in melting point between the low melting point components of the heat-extensible fiber and the heat-fusible conjugate fiber is more preferably 1.5 to 10 ° C.

  Further, the melting point of the high melting point component of the heat-extensible fiber is preferably 30 to 135 ° C. and more preferably 35 to 130 ° C. higher than the melting point of the low melting point component of the heat-fusible composite fiber. Thereby, the strength reduction etc. of a nonwoven fabric can be prevented or reduced more effectively. Furthermore, when the nonwoven fabric of the present invention is used as a surface sheet material of an absorbent article, when forming an end seal or a leak-proof groove by embossing or the like, the moldability is good and it is difficult to cause defects such as perforations. .

  The melting points of the high melting point component and the low melting point component of the heat-extensible fiber and the heat-fusible composite fiber are measured using a differential scanning calorimeter (DSC6200, manufactured by Seiko Instruments Inc.). A finely cut fiber sample (sample weight 2 mg) is subjected to thermal analysis at a heating rate of 10 ° C./min, and the melting peak temperature of the resin as the high melting point component or the low melting point component is measured. The melting point is defined by its melting peak temperature. When the melting point of a resin as a high melting point component or a low melting point component cannot be clearly measured by this method, this resin is defined as “resin having no melting point”. In this case, the temperature at which the resin component fuses is defined as the melting point of the high melting point component or the low melting point component as the temperature at which the resin component molecules start to flow.

  In the nonwoven fabric of the present invention, the intersections of the fibers are thermally fused. The heat fusion at the intersection of the fibers does not include a heat fusion part or the like formed by physically pressing the fiber web with an exothermic or heated member. In the nonwoven fabric of the present invention, the intersection between the first fiber and the second fiber and / or the intersection between the second fibers are heat-sealed through at least the melted and solidified low melting point component of the heat-fusible composite fiber. Preferably, the intersection between the first fibers, the intersection between the second fibers, and the intersection between the first fiber and the second fiber are more preferably heat-sealed. It is preferable that the heat fusion of the intersections of the fibers is performed by the air-through method. Such heat fusion ensures that the three-dimensional network of constituent fibers is maintained, and the nonwoven fabric of the present invention is bulky and easily secures the required strength, and has a compressive force in the thickness direction. When it is added, it is difficult to reduce the thickness, and the effects such as excellent thickness recovery after compression are also exhibited. Whether or not the intersection of the fibers is thermally fused by the air-through method can be determined by observing the nonwoven fabric with a scanning electron microscope.

The nonwoven fabric of the present invention, which is characterized by being bulky, has a thickness of 0.50 to 3.00 mm, particularly 1.00 to 3 when this is used as, for example, a surface sheet of an absorbent article. It is preferably 0.000 mm, particularly 1.50 to 3.00 mm. Further, the condition that the thickness is within this range, the nonwoven fabric of the present invention preferably has a basis weight of 10 to 80 g / m ^2, in particular 15 to 60 g / m ^2. The apparent density of the nonwoven fabric that is an index of bulkiness can be obtained by dividing the basis weight by the thickness. The thickness of the nonwoven fabric is measured by observing the longitudinal section of the nonwoven fabric. First, the nonwoven fabric is cut into a size of 100 mm × 100 mm, and a measurement piece is collected. A plate of 12.5 g (diameter 56.4 mm) is placed on the measurement piece, and a load of 49 Pa is applied. Under this state, the longitudinal section of the nonwoven fabric is observed with a microscope (manufactured by Keyence Corporation, VHX-900), and the thickness is measured.

The fiber diameter of the first fibers contained in the nonwoven fabric 10 is appropriately selected according to the specific use of the nonwoven fabric 10. For example, when the nonwoven fabric 10 is used as the surface sheet material of the absorbent article, the fiber diameter of the first fibers contained in the nonwoven fabric 10 is 10 to 35 μm, particularly 15 to 30 μm, especially 15 to 25 μm. It is preferable from the viewpoint of providing a good texture.
In the nonwoven fabric of this invention, since the 1st fiber is comprised from the heat | fever extensible fiber after heat-extending, the fiber diameter of the 1st fiber said here is the heat | fever extensible fiber after extending | stretching by heating. Refers to the fiber diameter. In general, when the heat-extensible fiber is stretched by heating, the fiber diameter becomes small.

  From the same viewpoint, the fiber diameter of the second fiber is preferably 10 to 35 μm, more preferably 15 to 30 μm, and particularly preferably 15 to 25 μm. These fiber diameters are measured by observing the nonwoven fabric with a scanning electron microscope.

  The nonwoven fabric of the present invention contains the first fiber and the second fiber in a mixed state. The mixing ratio of the first fiber and the second fiber (the former / the latter) is preferably 20/80 to 80/20 by mass ratio, and more preferably 30/70 to 70/30 by mass ratio. . By setting it as such a mixing ratio, it becomes easy to coexist with the bulkiness by expansion | extension of a heat | fever extensible fiber, and the maintenance and improvement of the various physical properties of a nonwoven fabric by coexisting a 2nd fiber. Examples of the various physical properties of the non-woven fabric include strength of the non-woven fabric and compression recovery in the thickness direction.

  The nonwoven fabric of the present invention may contain fibers other than the above-described first fibers and second fibers. Examples of such fibers include fibers that are not inherently heat-fusible (for example, natural fibers such as cotton and pulp, rayon and acetate fibers), acrylic fibers, and the like. For example, in the case of cotton, these fibers are contained in the nonwoven fabric for the purpose of imparting the nonwoven fabric with properties such as hygroscopicity. However, when fibers other than the first fiber and the second fiber are included, the total content of the fibers other than the first fiber and the second fiber in the nonwoven fabric is 5 to 30% by mass, particularly 5 to 15% by mass. It is preferable.

  In the nonwoven fabric of the present invention, the intersection of the constituent fibers is heat-sealed (preferably heat-sealed by an air-through method) so that the shape of the nonwoven fabric is maintained. May be further employed to maintain the form of the nonwoven fabric. Such means includes hot embossing. According to hot embossing, the constituent fibers of the nonwoven fabric are consolidated by consolidation with heat. The thickness of the embossed part formed in the nonwoven fabric by this consolidation is reduced compared to other parts of the nonwoven fabric. The embossed portion has, for example, a circular shape or a rectangular shape, and can be formed in a dotted shape over the entire area of the nonwoven fabric. Alternatively, a plurality of straight or curved embossed portions can be formed. A plurality of linear or curved embossed portions may be formed so as to cross each other.

  Next, the suitable manufacturing method of the nonwoven fabric of this invention is demonstrated, referring FIG. The apparatus 20 shown in FIG. 2 includes a web manufacturing unit 30, an embossing unit 40, a first hot air blowing unit 50, and a second hot air blowing unit 60. In the web manufacturing unit 30, the web 10 </ b> A is manufactured using fibers that are raw materials for the nonwoven fabric 10. As the web manufacturing unit 30, for example, a card machine 31 as shown in the figure can be used. Depending on the specific application of the nonwoven fabric 10, another web manufacturing apparatus such as an airlaid apparatus can be used instead of the card machine 31. The web 10A manufactured by the card machine 31 is in a state where its constituent fibers are loosely entangled with each other, and the shape retention as a sheet is not obtained. Therefore, in order to impart shape retention as a sheet to the web 10A, the web 10A is processed in the embossing section 40 to form the embossed web 10B.

  The embossing section 40 includes a pair of rolls 41 and 42 that are disposed to face each other with the web 10A interposed therebetween. Both rolls 41 and 42 are opposed to each other with a predetermined clearance, or the clearance is zero. The roll 41 is made of a metal engraving roll whose peripheral surface is processed to be uneven. The uneven pattern in the engraving roll can be appropriately selected according to the specific use of the nonwoven fabric 10. For example, when forming the rhombus lattice-shaped emboss pattern shown in FIG. 1, convex portions having a shape corresponding to the rhombus lattice may be formed on the peripheral surface of the roll 41. In addition, when it is desired to form a dot-like emboss pattern (not shown) on the nonwoven fabric 10, a convex portion having a shape corresponding to the dot may be formed on the peripheral surface of the roll 41. On the other hand, the roll 42 is composed of an anvil roll having a smooth peripheral surface. The roll 42 is made of metal, rubber, paper, or the like.

  In the embossed portion 40, the constituent fibers of the web 10A are consolidated by consolidation with or without heat to form a large number of joints on the web 10A, whereby the embossed web 10B is manufactured. Therefore, the roll 41 and / or the roll 42 has a heatable structure, and the roll 41 and / or the roll 42 is heated to a predetermined temperature as necessary when the embossing unit 40 is operated. The heating temperature when heating the roll 41 and / or the roll 42 is appropriately set according to the melting point and the heat extension start temperature of the heat-extensible fibers contained in the web 10A. Specifically, it is preferable that the heating temperature be −20 ° C. or higher and lower than the melting point of the high melting point component with respect to the melting point of the low melting point component of the heat extensible composite fiber. In the process in the embossing part 40, it is preferable that substantial elongation does not appear in the heat-extensible composite fiber. “Not substantially expressed” excludes intentionally stretching the heat-stretched composite fiber and inevitably causes a slight amount of heat-stretchable composite fiber due to temperature fluctuations in the embossed portion 40. The purpose of this is to allow extension.

  The embossed web 10 </ b> B to which shape retention is imparted by processing by the embossing unit 40 is then conveyed to the first hot air blowing unit 50. The first hot air blowing unit 50 includes a hood 51. The embossed web 10 </ b> B passes through the hood 51. A wire mesh conveyor belt 52 circulates in the hood 51, and the embossed web 10 </ b> B is placed on the conveyor belt 52 and conveyed. The conveyor belt 52 is made of a resin such as metal or polyethylene terephthalate.

  A blower (not shown) is disposed in the hood 51 so as to face the embossed web 10B to be conveyed. Hot air heated to a predetermined temperature is blown out from the blower toward the embossed web 10B. In the hood 51, a suction box (not shown) is disposed at a position facing the blower with the embossed web 10B and the conveyor belt 52 interposed therebetween. The hot air blown from the blower passes through the embossed web 10B and the conveyor belt 52 by the air-through method, and is sucked into the suction box. The sucked hot air is heated by a heater (not shown), sent to the blower, and blown again to the embossed web 10B. That is, the hot air circulates between the blower and the suction box. By this circulation, hot air can be efficiently blown.

In the 1st hot air spraying part 50, the heat | fever extensible fiber contained in the embossing web 10B is extended | expanded by the blowing of the hot air of an air through system. When forming an embossed web containing a heat-extensible fiber and a heat-fusible composite fiber in a mixed state, the heat-extensible fiber of the heat-fusible composite fiber is in a stage where the heat-extensible fiber is not sufficiently stretched. When the low melting point component melts, the low melting point component of the melted heat-fusible composite fiber prevents the web from becoming bulky due to the elongation of the heat-extensible fiber, making it difficult to express the bulk. Moreover, it is very difficult to recover the bulk of the embossed web 10B that has been crushed.
Therefore, in the present manufacturing method, the heat treatment for the embossed web 10B is performed by a first stage in which hot-extrusion fibers are blown by blowing hot air by an air-through method, and then hot air is blown by an air-through method, The crossing point of the fusible conjugate fiber is divided into the second stage to obtain a nonwoven fabric by heat fusing, and after the heat extensible fiber is sufficiently stretched, the crossing point between the fibers is heat fused. . For this purpose, in the first hot air blowing unit 50 which is the first stage hot air blowing, hot air having a temperature lower than that of the hot air in the second hot air blowing unit 60 is blown.

As specific conditions, the temperature of the first stage hot air blowing is 2 to 20 ° C. lower than the melting point of the low melting point component of the heat-extensible fiber, more preferably 2 to 15 ° C., more preferably 2 to 2 ° C. A temperature lower by 10 ° C. is preferable from the viewpoint of preventing or reducing the elongation of the heat-extensible fibers and easily obtaining a bulky nonwoven fabric.
Also, on the condition that the temperature of the second stage hot air blowing is higher than the temperature of the hot air in the first hot air blowing section 50, the temperature is 20 ° C. lower than the melting point of the low melting point component of the heat-fusible conjugate fiber. It is preferable that the temperature is up to a high temperature and less than the melting point of the high-melting component of the heat-extensible fiber and the heat-fusible conjugate fiber, more preferably the low-melting-point component of the heat-fusible conjugate fiber. It is a temperature from a temperature 2 ° C. lower than the melting point to a temperature higher than 15 ° C. and less than the melting point of the high-melting component of the heat-extensible fiber and the heat-fusible composite fiber, This is preferable from the viewpoint of preventing or reducing the decrease in strength.
The method described above is used for measuring the melting point. The temperature of the hot air was measured at a position 10 cm above the embossed web 10B. As the measuring means, for example, a thermocouple type temperature sensor and a temperature indicator are used. The hot air blowing temperature is measured on the hot air blowing surface side of the embossed web 10B.

  In addition, since heat-extensible fibers generally tend to have a lower Young's modulus than ordinary fibers (non-heat-extensible fibers), when hot air is blown at a high wind speed, the fibers are elongated, but the embossed web 10B is at wind pressure. It will be crushed and it will become difficult to express bulkiness. Therefore, for the purpose of thermally expanding the thermally stretchable fiber while preventing the embossed web 10B from being crushed as much as possible, the first hot air blowing unit 50, which is the first stage hot air blowing, and the second stage hot air blowing are used. In a certain second hot air blowing unit 60, the hot air blowing speed is preferably 0.05 to 10 m / sec, and more preferably 0.2 to 2.5 m / sec. The blowing speed of the hot air is a value measured using ANNOMASTER MODEL 6162 and MODEL 0203 manufactured by KANOMAX at a position 10 cm above the embossed web 10B. The hot air blowing time is preferably 0.05 to 10 seconds, particularly preferably 0.05 to 5 seconds, provided that the temperature and speed of the hot air are within the above-described ranges.

  By adopting the above-mentioned spraying conditions, the heat-extensible fibers are stretched by thermally fusing the heat-fusible conjugate fibers and the heat-extensible fibers and the heat-fusible conjugate fibers contained in the embossed web 10b. Can be prevented or reduced more reliably. In addition, expansion | extension of a heat | fever extensible fiber and fusion | melting of heat | fever extensible fibers generate | occur | produce preferentially in the hot air blowing surface side among the two surfaces of the embossed web 10B. In other words, the heat-extensible fibers on the side of the surface abutting the conveyor belt 52 do not stretch relative to the heat-extensible fibers on the side of the hot air blowing surface, and the intersections of the fibers are relatively fused. Not done.

  Since the fibers located at the joint portion in the embossed web 10B are consolidated, no elongation occurs even when hot air is blown. Elongation occurs for thermally extensible fibers present in portions other than the joint. That is, it is a part between joining parts that a heat | fever extensible fiber expand | extends. And since the part of the heat-extensible fiber is fixed by the joining portion, the elongation of the extended heat-extensible fiber loses its place in the plane direction of the embossed web 10B, and the thickness of the embossed web 10B. Move in the direction. Thereby, convex portions are formed between the joint portions, and the embossed web 10B becomes bulky. Moreover, it comes to have the three-dimensional appearance in which many convex parts were formed. Thus, the target nonwoven fabric 10 is obtained.

  FIG. 3 discloses another embodiment of the production method of the present invention. With respect to the embodiment shown in FIG. 3, points different from the above-described embodiment will be described, and the description regarding the above-described embodiment is appropriately applied to points not particularly described. 3, the same members as those in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted.

The embodiment shown in FIG. 3 is different from the embodiment described above in that the nonwoven fabric 90 is manufactured in one manufacturing line in the embodiment described above, whereas the nonwoven fabric 90 is manufactured in this embodiment. It is stored in the state of the wound body 100 once wound in a roll shape, and then the non-woven fabric 90 is drawn out from the wound body 100 in another facility in the factory or another facility outside the factory, and the third hot air blowing unit 70 In this case, hot air is blown onto the nonwoven fabric 90 by an air-through method to restore the bulk of the nonwoven fabric.
The bulk of the nonwoven fabric 90 in a state of being wound in a roll shape is reduced by the winding pressure. In particular, since the nonwoven fabric has a bulky uneven shape as described above, the reduction in bulk due to the winding pressure is significant. In addition, by applying the hot air blowing process, the heat-extensible fibers existing in a stretchable state by heating are further stretched apart from recovering the bulk that has been reduced by the winding pressure. This bulk recovery becomes even more pronounced when the non-woven fabric contains non-heat-extensible heat-fusible conjugate fibers.

In the embodiment shown in FIG. 3, a drum-type hot air blowing device 7 is used for the third hot air blowing unit 70. The drum-type hot air spraying device 7 includes a transport drum 71 having a peripheral surface formed by a breathable member and a hood 72 that covers the transport drum 71 from above.
The transport drum 71 rotates in the direction indicated by the arrow in FIG. The nonwoven fabric 90 fed out from the wound body 100 is transported while being held on the peripheral surface of the rotating transport drum 71. Further, a blower (not shown) is disposed in the hood 71 so as to face the nonwoven fabric 90 being conveyed. Hot air heated to a predetermined temperature is blown out from the blower toward the nonwoven fabric 90 being conveyed. Further, a suction box (not shown) is disposed on the transfer drum 71 at a position facing the blower with the nonwoven fabric 90 interposed therebetween. The hot air blown from the blower passes through the nonwoven fabric 10 by the air-through method and is sucked into the suction box. The sucked hot air is heated by a heater (not shown), then sent to the blower, and sprayed onto the nonwoven fabric 90 again. That is, the hot air circulates between the blower and the suction box in the same manner as the first and second hot air blowing units 50 and 60. By this circulation, hot air can be efficiently blown.
By applying a bulk recovery process by blowing hot air to the nonwoven fabric 90 which has been reduced in volume as the wound body 100, a bulky nonwoven fabric 80 whose bulk has been recovered is obtained.

  FIG. 4 discloses still another embodiment of the production method of the present invention. Regarding the embodiment shown in FIG. 4, points different from the above-described embodiment will be described, and the description regarding the above-described embodiment is appropriately applied to points that are not particularly described. In FIG. 4, the same members as those in FIG. 2 or FIG.

  In the embodiment shown in FIG. 4, after the hot air is blown in the first hot air blowing section 50, the first stage of hot air that extends the heat-extensible fibers is blown to produce the nonwoven fabric semi-finished product 10 </ b> C. Is stored in the state of the wound body 100 once wound in a roll shape, and thereafter, the non-woven fabric semi-finished product 10C is fed out from the wound body 100 in another facility in the factory or another facility outside the factory, Hot air is blown onto the semi-finished product 10C by an air-through method, the heat-extensible fibers are further extended, and the intersections of the heat-extensible fibers and the heat-fusible composite fibers are heat-sealed. The bulk of the product 10C is recovered.

  The bulk of the nonwoven fabric semi-finished product 10C wound in a roll shape is reduced by the winding pressure. In particular, since the nonwoven fabric semi-finished product 10C has a bulky uneven shape, the reduction in bulk due to the winding pressure is remarkable. The nonwoven fabric semi-finished product 10 </ b> C in this state is subjected to the hot air blowing process again in the second hot air blowing unit 60, thereby further extending the thermally stretched fibers and increasing the bulk. In addition to the expansion of the heat-extensible fibers, the bulk that has been reduced by the winding pressure is recovered by being subjected to a process of blowing hot air. This bulk recovery becomes even more pronounced when the non-woven fabric semi-finished product 10C contains non-heat-extensible heat-fusible conjugate fibers. As the hot air blowing condition in the second hot air blowing unit 60, the temperature of the hot air blown in the second stage is set higher than the temperature of the hot air in the first stage, as in the above-described embodiment. Thereby, the target nonwoven fabric 80 is obtained.

In the embodiment shown in FIG. 4, a drum-type hot air blowing device 7 is used for the second hot air blowing unit 60.
In the 2nd hot air spraying part 60 in the embodiment shown in FIG. 4, temperature higher than the spraying condition in the 1st hot air spraying part 50 is employ | adopted as hot air spraying conditions. The reason for adopting the high temperature is that the low melting point component of the heat-fusible composite fiber having a higher melting point than the low melting point component of the heat-extensible fiber is melted, and the first and second fibers are melted by the melted low melting point component. This is to impart sufficient strength to the nonwoven fabric by heat-sealing the intersection with the second fiber and the intersection between the second fibers.

As a specific condition, the second stage hot air blowing temperature is 2 ° C. higher than the melting point of the low melting point component of the heat-fusible composite fiber, provided that the temperature of the hot air in the first hot air blowing unit 50 is higher. It is preferably less than the melting point of the high-melting component of each of the heat-extensible fiber and the heat-fusible conjugate fiber, and more preferably the low-melting component of the heat-fusible conjugate fiber at a temperature from a low temperature to a temperature 20 ° C higher. It is preferable that the temperature is lower than the melting point of the high-melting component of the heat-extensible fiber and the heat-fusible conjugate fiber at a temperature from 2 ° C. to 15 ° C.
The temperature of the hot air was measured at a position 10 cm above the embossed web 10B. As the measuring means, for example, a thermocouple type temperature sensor and a temperature indicator are used. The hot air blowing temperature is measured on the hot air blowing surface of the embossed web 10B.
The hot air blowing speed is preferably 0.05 to 10 m / sec, more preferably 0.2 to 2.5 m / sec. Moreover, it is preferable that it is 0.05 to 10 second, especially 0.05 to 5 second on the condition that the temperature and wind speed of the hot air in the 2nd hot air blowing part 70 are in the range mentioned above. The method for measuring the melting point of the resin as the high melting point component and / or the low melting point component and the temperature and speed of the hot air are the same as those described above.

  By blowing hot air in the second hot air blowing part 60, the low melting point component of the heat-fusible composite fiber is melted, and by the melted low melting point component, the intersection of the first fiber and the second fiber and the second fibers are in contact with each other. The intersections are heat-sealed to give the nonwoven fabric sufficient strength and / or excellent compression recovery. In addition, in the first stage of blowing hot air, if the heat-extensible fibers are not sufficiently stretched or the heat fusion at the intersection of the heat-extensible fibers is insufficient, the heat-extensible fibers may be further stretched, It is also possible to heat-bond the intersections of the fibers. Accordingly, the nonwoven fabric semi-finished product 10C has improved strength and compression recovery property, and further improved bulkiness depending on conditions, and the intended nonwoven fabric 80 is obtained.

  As is apparent from the above description, the blowing of hot air in the second hot air blowing unit 60 can be performed while maintaining the bulkiness of the nonwoven fabric semi-finished product 10C that is bulky in the first hot air blowing unit 50. preferable. From this point of view, the hot air blowing surface in the second hot air blowing unit 70 may be opposite to the hot air blowing surface in the first hot air blowing unit 50. In this case, the non-woven fabric semi-finished product 10C may be blown by hot air from the inside to the outside of the transport drum 71 without inverting the front or back, or the non-woven fabric semi-finished product 10C may be applied to the transport drum 71. It is also possible to invert the front and back before embracing the peripheral surface and then embed it on the peripheral surface and blow hot air from the outside to the inside of the transfer drum 71 in an air-through manner. Or as long as it is an air through system, you may spray a hot air from both surfaces of the semi-finished product 10C of a nonwoven fabric.

  The nonwoven fabric 10 and / or the nonwoven fabric 80 obtained in this way can be applied to various fields that make use of the uneven shape, bulkiness, and high strength or good compression recovery. For example, surface sheets, second sheets (sheets disposed between the surface sheet and the absorbent body), gather forming sheets, back sheets, leak-proof sheets, or humans in the field of disposable hygiene articles such as disposable diapers and sanitary napkins It is suitably used as a wiping sheet, a skin care sheet, and an objective wiper.

  Next, the heat-extensible conjugate fiber and the heat-fusible conjugate fiber, which are raw materials for the first fiber and the second fiber, will be further described.

  When the high-melting component in the heat-extensible composite fiber that is the raw material of the first fiber is the first resin component and the low-melting component is the second resin component, it is sufficient that the orientation index is a specific value. It is preferable from the viewpoint of expression of extensibility. The orientation index of the resin is naturally different depending on the resin to be used. For example, when a polypropylene resin is used as the first resin component, the orientation index is preferably 60% or less, particularly 40% or less, and more preferably 25% or less. When the first resin component is polyester, the orientation index is preferably 25% or less, particularly 20% or less, and more preferably 10% or less. On the other hand, the second resin component preferably has an orientation index of 5% or more, particularly 15% or more, and more preferably 30% or more. The orientation index is an index of the degree of orientation of the polymer chain of the resin constituting the fiber. And when the orientation index of a 1st resin component and a 2nd resin component is each said value, a heat | fever extensible composite fiber comes to expand | extend by heating.

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

  Intrinsic birefringence refers to birefringence in the state where the polymer polymer chains are perfectly oriented. The values are, for example, the first edition of “Plastic Materials in Molding”, and the typical plastic materials used in molding processes (plastics). Edited by the Japan Society for Molding and Processing, Sigma Publishing, published on February 10, 1998).

The birefringence in the heat-extensible composite fiber is measured under polarization in a direction parallel to and perpendicular to the fiber axis by attaching a polarizing plate to an interference microscope. As the immersion liquid, a standard refraction liquid manufactured by Cargille is used. The refractive index of the immersion liquid is measured with an Abbe refractometer. From the interference fringe image of the composite fiber obtained by the interference microscope, the refractive index in the direction parallel and perpendicular to the fiber axis is obtained by the calculation method described in the following document, and the birefringence as the difference between the two is calculated.
“Fiber structure formation in high-speed spinning of core-sheath type composite fiber”, page 408 (Journal of the Fiber Society, Vol. 51, No. 9, 1995)

  The heat stretchable conjugate fiber can be stretched by heat at a temperature lower than the melting point of the first resin component. The heat-extensible conjugate fiber preferably has a thermal elongation rate of 0.5 to 20%, particularly 3 to 20%, particularly 5.0 to 20% at a temperature 10 ° C higher than the melting point of the second resin component. . When a nonwoven fabric is produced using fibers having such a thermal elongation rate as a raw material, the nonwoven fabric becomes bulky due to the elongation of the fibers.

The thermal elongation rate of the fiber is measured by the following method. A thermomechanical analyzer TMA / SS6000 manufactured by Seiko Instruments Inc. is used. As a sample, after preparing a plurality of fibers having a fiber length of 10 mm or more so that the total weight per 10 mm of the fiber length is 0.5 mg, and arranging the plurality of fibers in parallel, Mount on the device with 10mm distance between chucks The measurement start temperature is 25 ° C., and the temperature is increased at a temperature increase rate of 5 ° C./min with a constant load of 0.73 mN / dtex applied. The amount of elongation of the fiber at that time was measured, and the amount of elongation at a temperature lower by 3.5 ° C. than the melting point of the second resin component of the heat-extensible fiber and the melting point of the second resin component of the heat-fusible conjugate fiber were 10 Read the amount of elongation at a high temperature. When the respective elongation amounts are X1 mm and X2 mm, the respective thermal elongation rates are expressed by the following formulas.
(X1 / 10) x 100 (%)
(X2 / 10) × 100 (%)
The reason for measuring the thermal elongation at the above-mentioned temperature is that, as will be described later, the first stage of sufficiently stretching the heat-extensible fiber by heating, and melting the low melting point component of the heat-extensible fiber and the heat-fusible composite fiber This is because the nonwoven fabric 10 is manufactured by the second stage in which the intersections of the fibers are sufficiently heat-sealed. First, in the first stage, heat treatment is prevented or reduced by heat treatment at a temperature lower than the melting point of the second resin component of the heat stretchable fiber, specifically about 3.5 ° C. This is because, in the second stage, the heat treatment is usually performed at a temperature not lower than the melting point of the second resin component of the heat-fusible conjugate fiber and up to about 10 ° C. above them.

  In order for the heat-extensible composite fiber to achieve the above-described heat elongation rate, for example, a first resin component and a second resin component having different melting points are used, and melt spinning is performed at a low speed of less than 2000 m / min. After obtaining the fiber, the composite fiber may be heat-treated and / or crimped. In addition to this, the stretching process may be avoided.

  As the crimping process, it is convenient to perform mechanical crimping. There are two-dimensional and three-dimensional forms of mechanical crimping. In addition, there are three-dimensional manifested crimps found in the eccentric type core-sheath type composite fiber and side-by-side type composite fiber. Any aspect of crimping may be performed in the present invention. The crimping process may be accompanied by heating. Moreover, you may heat-process after a crimping process. Furthermore, in addition to the heat treatment after the crimping treatment, a separate heat treatment may be performed before the crimping treatment. Or you may perform a heat processing separately, without performing a crimping process.

  In the crimping process, the fiber may be somewhat stretched, but such stretching is not included in the stretching process referred to in the present invention. The drawing treatment referred to in the present invention refers to a drawing operation with a draw ratio of 2 to 6 times that is usually performed on undrawn yarn.

  Appropriate conditions for the heat treatment are selected according to the types of the first and second resin components constituting the composite fiber. The heating temperature is lower than the melting point of the second resin component. For example, when the heat-extensible conjugate fiber is a core-sheath type, the core component is polypropylene or polyester, and the sheath component is high-density polyethylene, the heating temperature is preferably 50 to 120 ° C., particularly preferably 70 to 115 ° C. The time is preferably 10 to 1800 seconds, particularly 20 to 1200 seconds. Examples of the heating method include hot air blowing and infrared irradiation. As described above, this heat treatment can be performed after the crimping treatment.

  There is no restriction | limiting in particular in the kind of 1st resin component and 2nd resin component, What is necessary is just resin with fiber formation ability. In particular, the difference in melting point between the two resin components, or the difference between the melting point of the first resin component and the softening point of the second resin component is 20 ° C. or more, particularly 25 ° C. or more. It is preferable because it can be easily performed. When the heat-extensible conjugate fiber is a core-sheath type, a resin having a melting point of the core component higher than that of the sheath component is used. In particular, it is preferable to use a core-sheath type thermally stretchable conjugate fiber having a polyester such as polypropylene (PP) or polyethylene terephthalate (PET) as a core and a resin having a lower melting point than these as a sheath. As a preferable combination of the first resin component and the second resin component, as the second resin component when the first resin component is PP, the high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear Although polyethylene, such as low density polyethylene (LLDPE), ethylene propylene copolymer, polystyrene, etc. are mentioned, it is preferable that it is LLDPE. In addition, when a polyester resin such as PET or polybutylene terephthalate (PBT) is used as the first resin component, in addition to the example of the second resin component described above, PP, copolymer polyester, etc. may be used as the second resin component. Can be mentioned. Furthermore, examples of the first resin component include polyamide-based polymers and two or more types of copolymers of the first resin component described above, and examples of the second resin component include two or more types of the second resin component described above. Copolymers are also included. These are appropriately combined.

  The ratio (mass ratio) of the first resin component and the second resin component in the heat-extensible composite fiber is 10:90 to 90: 10%, particularly 20:80 to 80: 20%, especially 50:50 to 70:30. % Is preferred. Within this range, the mechanical properties of the fiber are sufficient, and the fiber can withstand practical use. Further, the amount of the fusion component is sufficient, and the fibers are sufficiently fused. Moreover, it is preferable that the ratio of the 1st resin component used as a core is large from a viewpoint of making the card | curd permeability favorable when it uses as a raw material of the nonwoven fabric manufactured with a card machine, without impairing extensibility.

  As the heat-extensible fiber, in addition to the above-described heat-extensible composite fiber, Japanese Patent No. 4131852, Japanese Patent Laid-Open No. 2005-350836, Japanese Patent Laid-Open No. 2007-303035, Japanese Patent Laid-Open No. 2007-204899, Japanese Patent The fibers described in 2007-204901 and JP-A-2007-204902 can also be used.

  From the viewpoint of successfully fusing the heat-extensible fiber and the heat-fusible conjugate fiber, the heat-fusible conjugate fiber used as the raw material for the heat-extensible fiber and the low-melting-point component in the heat-extensible conjugate fiber The low melting point component in the heat-fusible conjugate fiber is preferably the same type of resin, or in the case of different types, having compatibility.

  In the heat-fusible conjugate fiber, the weight ratio of the high melting point component / low melting point component is preferably 6/4 to 2/8, particularly preferably 5/5 to 3/7. That is, it is preferable to contain a large amount of low melting point components. As a result, heat fusion by the air-through method occurs surely. This weight ratio can be calculated from the cross-sectional area of each of the high-melting component and the low-melting component measured by observing the cross-section of the heat-fusible conjugate fiber, and the density of each of the high-melting component and the low-melting component. As another means for surely causing the thermal fusion by the air-through method, it is possible to use one having a melt index of the low melting point component in the heat-fusible conjugate fiber of 10 to 40 g / 10 min, particularly 10 to 25 g / 10 min. preferable. The melt index is measured according to JIS K7210 under conditions of 190 ° C. and a load of 2.16 kg.

  As the resin of the heat-fusible composite fiber suitably used in relation to the above-described heat-extensible composite fiber, polypropylene or polyethylene terephthalate is used as a high melting point component, high density polyethylene (HDPE) as a low melting point component, and low density Examples thereof include combinations using polyethylene such as polyethylene (LDPE) and linear low density polyethylene (LLDPE), ethylene propylene copolymer, polystyrene, polypropylene, and copolyester. Among these, a combination using polypropylene or polyethylene terephthalate as the high melting point component and using high density polyethylene (HDPE) as the low melting point component is particularly preferable.

  A fiber web in which a heat-extensible composite fiber and a heat-fusible composite fiber are mixed can be easily manufactured by putting both fibers into a card machine. From the viewpoint of satisfactorily forming the fiber web with a card machine, the fiber length of both fibers is preferably about 30 to 70 mm.

As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to the said embodiment. For example, in the above manufacturing method, the card web 10A is hot embossed to produce an embossed web 10B, and the embossed web 10B is subjected to air-through processing. Instead, the hot embossing is not performed. The card web 10A may be directly subjected to air-through processing. In addition, after the semi-finished product 10C after the air-through processing is performed by the first hot air spraying unit 50, the semi-finished product 10C is once cooled by a cooling unit (not shown), and then the second hot air spraying unit 60 is applied to the semi-finished product 10C. Air through processing may be applied.
Further, as in the embodiment shown in FIG. 4, after the semi-finished product 10 </ b> C after the air-through processing is performed by the first hot air blowing unit 50 is wound up into one end roll shape, On the other hand, the semi-finished product 10C subjected to the air-through processing by the first hot-air spraying unit 50 instead of performing the air-through processing at the second hot-air spraying unit 60 in which the drum-type hot air spraying device 7 is disposed is replaced with a drum-type product 10C. Alternatively, the second stage air-through processing may be performed by directly introducing the hot air blowing device 7.

  Moreover, the nonwoven fabric of this invention is not restricted to the thing of a single layer structure containing a 1st fiber and a 2nd fiber, The fiber layer containing a 1st fiber and a 2nd fiber, and 1 or 2 or more other fiber containing another fiber A non-woven fabric having a multilayer structure having a laminated structure with a fiber layer may be used. Further, it may be a composite nonwoven fabric obtained by laminating and integrating another nonwoven fabric with a single layer nonwoven fabric including the first fiber and the second fiber.

  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.

[Examples 1-2, Comparative Examples 1-3]
The nonwoven fabric shown in FIG. 1 was manufactured according to the method shown in FIG. 3 under the conditions shown in Table 2 using the heat-extensible conjugate fiber and the heat-fusible conjugate fiber shown in Table 1 as raw materials. The emboss pattern is as shown in FIG. 1 and has a rhombus lattice shape with an emboss line width of 0.5 mm. The embossing rate of this nonwoven fabric was 14.1%. Moreover, the embossing temperature was 110 degreeC using hot embossing for formation of a junction part (concave part 18). In the production of these nonwoven fabrics, a wound body 100 in which the nonwoven fabric 90 was once wound into a roll shape was obtained. The nonwoven fabric 90 fed out from the wound body 100 was used as a nonwoven fabric before storage. In the evaluation of the bulk recovery property, the nonwoven fabric 90 was fed out from the wound body 100, and hot air was blown onto the nonwoven fabric 90 by an air-through method to recover the bulk of the nonwoven fabric.
The heat-extensible conjugate fiber is melt-spun at a take-up speed of 1300 m / min. After melt spinning, the heat-extensible conjugate fiber was immersed in an aqueous solution of a hydrophilizing agent to adhere the hydrophilizing agent. Next, after mechanical crimping, the fiber was dried by heat treatment and cut to obtain short fibers (fiber length 51 mm). In addition, the drawing process is not performed to manufacture the fiber. In addition, the extending | stretching process here means the extending | stretching operation of about 2-6 times normally performed with respect to the undrawn yarn obtained after melt spinning.

[Evaluation]
The nonwoven fabrics obtained in Examples and Comparative Examples were measured for thickness (thickness before storage) and apparent density (apparent density before storage), and the apparent density serving as an index of bulkiness was evaluated according to the following evaluation criteria. Moreover, about the obtained nonwoven fabric, bulk recovery property, nonwoven fabric strength, and touch (fluffy feeling) were measured and evaluated by the method mentioned later, respectively. The results are shown in Table 3.

[Measurement of thickness and apparent density of nonwoven fabric]
The apparent density that is an index of the bulkiness of the nonwoven fabric can be obtained by dividing the basis weight by the thickness. The thickness of the nonwoven fabric is measured by observing the longitudinal section of the nonwoven fabric. First, the nonwoven fabric is cut into a size of 100 mm × 100 mm, and a measurement piece is collected. A plate of 12.5 g (diameter 56.4 mm) is placed on the measurement piece, and a load of 49 Pa is applied. Under this state, the longitudinal section of the nonwoven fabric is observed with a microscope (manufactured by Keyence Corporation, VHX-900), and the thickness is measured. The lower the value of the apparent density of the nonwoven fabric, the higher the evaluation.

[Bulk recoverability of nonwoven fabric]
The nonwoven fabric is wound around a paper tube having an outer diameter of 85 mm in a roll shape with a length of 2700 m and stored at room temperature for 2 weeks. The non-woven fabric after storage is drawn out at a conveyance speed of 150 m / min in a range outside the diameter of 500 mm and inside the diameter of 600 mm, a treatment temperature of 115 ° C., a treatment time of 0.20 seconds, and a wind speed of 2.8 m / second. The nonwoven fabric thickness is recovered by spraying hot air on the nonwoven fabric. For the bulk recoverability of the nonwoven fabric, the thickness of the convex portion of the nonwoven fabric (thickness before storage) before winding the nonwoven fabric into a roll shape was C, and the thickness of the convex portion of the nonwoven fabric after hot air blowing (thickness after recovery) was D. Is represented by the following equation (2). The measurement of the nonwoven fabric thickness after hot air spraying is measured 1 minute to 1 hour after hot air spraying. The thickness of the nonwoven fabric is measured by the method described above.
Bulk recovery (%) = D / C × 100 (2)
The case where the bulk recoverability calculated by the formula (2) is less than 60% is x, the case where it is 60% or more to less than 70% is Δ, the case where it is 70% or more to less than 80% is ◯, the case where it is 80% or more is ◎ And evaluate. The higher the bulk recovery value, the higher the evaluation.

[Nonwoven fabric strength]
A non-woven fabric is cut out in a size of 200 mm in the machine flow direction (MD direction) and 50 mm in a direction perpendicular to the machine direction (CD direction), and this is used as a test piece. This test piece is attached to a tensile tester AG-IS manufactured by Shimadzu Corporation, with a chuck interval of 150 mm, and a tensile test is performed at a tensile speed of 300 mm / min. The maximum strength at that time is defined as the strength of the nonwoven fabric. Here, since the nonwoven fabric strength greatly depends on the basis weight of the nonwoven fabric, the value obtained by dividing the nonwoven fabric strength by the basis weight is defined as the MD strength per unit basis weight, the CD strength, and the strength of the nonwoven fabric. It is used as an indicator.

[Feel (fullness)]
Place the non-woven fabric on a flat table with the convex part facing up. Ten monitors were evaluated for the touch feeling in the palm of the following three criteria. The results are shown as an average of 10 people.
Criterion 3: There is a feeling of plumpness.
2: Slightly plump.
1: There is no plump feeling.
Evaluation results A: Judgment average 2.5 or more to 3.0 or less B: Judgment average 2.5 or more to 3.0 or less Δ: Judgment average 1.5 or more to less than 2.5 ×: Judgment average 1 or more to 1. Less than 5

  As is clear from the results shown in Table 3, the nonwoven fabric obtained in each example is bulky and has a heat-fusible property even though it contains heat-fusible conjugate fibers in a mixed state. It can be seen that the combined use of the composite fiber is excellent in bulk recovery by blowing hot air. Moreover, it turns out that the intensity | strength of a nonwoven fabric is high and the touch is favorable.

DESCRIPTION OF SYMBOLS 10,80 Nonwoven fabric 18 Concave part 19 Convex part 20 Manufacturing apparatus 30 Web manufacturing part 40 Embossing part 50 1st hot-air spraying part 60 2nd hot-air spraying part 70 3rd hot-air spraying part 7 Drum-type hot-air spraying apparatus

Claims (5)

A first fiber that contains two components having different melting points and whose length is increased by heating as a raw material, and a second fiber that uses a heat-fusible composite fiber containing two components having different melting points as a raw material Including a nonwoven fabric in which the intersection of the fibers is heat-sealed,
A non-woven fabric in which the melting point of the low-melting-point component of the heat-extensible fiber is lower than the melting point of the low-melting-point component of the heat-fusible composite fiber, and the difference between the melting points is 1.5 to 10 ° C.   The non-woven fabric according to claim 1, wherein the heat-fusible conjugate fiber is a non-heat-extensible fiber whose length does not substantially extend by heating.   The mixing ratio of the first fiber and the second fiber (the former / the latter) is 20/80 to 80/20 in mass ratio, the intersection of the first fibers, the intersection of the second fibers, and the first fiber and the first fiber The nonwoven fabric according to claim 1 or 2, wherein the intersections with the two fibers are each thermally fused by an air-through method. It is a manufacturing method of the nonwoven fabric according to claim 1,
Hot air is blown by an air-through method onto a fiber web containing two components having different melting points and a heat-extensible fiber having a length that is increased by heating and a heat-fusible composite fiber containing two components having different melting points. A first stage in which a stretchable fiber is stretched to obtain a nonwoven fabric precursor, hot air is blown onto the nonwoven fabric precursor in an air-through manner, and the intersection of the heat stretchable fiber and the heat-fusible composite fiber is heat-sealed. Including a second step of obtaining a nonwoven fabric,
The temperature of the hot air blown in the first stage is set to a temperature lower than the melting point of the low melting point component of the heat-extensible fiber, and the temperature of the hot air blown in the second stage is set to a temperature higher than the temperature of the hot air in the first stage. The manufacturing method of the nonwoven fabric to do.   The temperature of the hot air blown in the first stage is 2 to 20 ° C. lower than the melting point of the low melting point component of the heat-extensible fiber, and the temperature of the hot air blown in the second stage is the low melting point of the heat-fusible conjugate fiber. The method for producing a nonwoven fabric according to claim 4, wherein the temperature is from 2 ° C to 20 ° C higher than the melting point of the component.

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