AU2015307582A1

AU2015307582A1 - Absorbent and absorbent article including absorbent

Info

Publication number: AU2015307582A1
Application number: AU2015307582A
Authority: AU
Inventors: Takashi Maruyama; Masashi Uda
Original assignee: Unicharm Corp
Current assignee: Unicharm Corp
Priority date: 2014-08-26
Filing date: 2015-08-11
Publication date: 2017-04-13
Anticipated expiration: 2035-08-11
Also published as: WO2016031569A1; JP6173276B2; AU2015307582B2; MY184262A; JP2016043197A; CN106714757B; CN106714757A

Abstract

　The purpose of the present invention is to provide an absorbent which is flexible, not prone to creasing, and not prone to losing shape. This absorbent is configured as described below. An absorbent (3) for an absorbent article (1) having a longitudinal direction and a width direction, the absorbent (3) characterized in that the absorbent (3) is provided with an absorbing core (5) having a first face (9) and a second face (10) on a reverse side thereof from the first face (9), the absorbing core (5) includes thermoplastic resin fibers (6), cellulose-based water-absorbent fibers (7), and a high-absorbent polymer (8), at least a portion of the thermoplastic resin fibers (6) have a first portion (6a) exposed to the first face (9) of the absorbing core (5), a second portion (6b) exposed to the second face (10) of the absorbing core (5), and a connecting portion (6c) for connecting the first portion (6a) and the second portion (6b), and the absorbent (3) has a recovery of at least 85% after folding.

Description

P150384WO - 1 -

DESCRIPTION

Title of Invention

ABSORBENT AND ABSORBENT ARTICLE INCLUDING ABSORBENT

Technical Field [0001]

The present invention relates to an absorbent body and to an absorbent article comprising the absorbent body.

Background Art [0002]

There are currently being marketed absorbent articles, such as disposable diapers, wherein the absorbent body includes abundant amounts of a superabsorbent polymer for the purpose of absorbing large amounts of excreta, such as urine from the wearer. However, absorbent bodies containing abundant amounts of superabsorbent polymers have been problematic in that the position of the superabsorbent polymer shifts during use, the superabsorbent polymer falls off from the absorbent body, and the absorbent body becomes deformed as it absorbs fluid.

[0003]

Absorbent bodies designed to overcome these problems include such types having an absorbent retaining layer comprising fluff pulp, a superabsorbent polymer and heat sealable synthetic resin fibers, and a nonwoven fabric layer composed of heat sealable synthetic resin fibers which is situated on the front sheet side of the absorbent retaining layer (PTL 1 and PTL 2). In the absorbent bodies described in PTL 1 and PTL 2, the heat sealable synthetic resin fibers in the absorbent retaining layer are tangled or heat-fused together, and the heat sealable synthetic resin fibers in the absorbent retaining layer and the heat sealable synthetic resin 2 fibers in the nonwoven fabric layer are heat-fused.

Citation List Patent Literature [0004] PTL 1 Japanese Unexamined Patent Publication No. 2002-11047 PTL 2 Japanese Unexamined Patent Publication No. 2008-513154

Summary of Invention Technical Problem [0005]

In PTL 1, heat-fusion of the absorbent retaining layer and the nonwoven fabric layer is carried out at their contact surfaces, thereby improving the bonding strength between them, and the fusible synthetic resin fibers are heat fused together in the absorbent retaining layer, so that deformation of the absorbent body can be reduced. With the absorbent body described in PTL 1, however, the degree of heat fusion is increased, tending to render the absorbent body hard. A similar situation results with PTL 2 as well.

It is therefore an object of the present invention to provide an absorbent body that is soft, less prone to fold-creasing, and resistant to deformation.

Solution to Problem [0006]

The present inventors have found an absorbent body for an absorbent article having a lengthwise direction and a widthwise direction, wherein the absorbent body comprises an absorbent core having a first surface and a second surface on opposite side thereof, the absorbent core includes thermoplastic resin fibers, cellulosic water-absorbent fibers and a superabsorbent polymer, at least some of the thermoplastic resin fibers have a first 3 section exposed on the first surface of the absorbent core, a second section exposed on the second surface of the absorbent core, and a connected section connecting the first section and second section, and the absorbent body has a folding recovery percentage of 85% or greater.

Advantageous Effects of Invention [0007]

The absorbent body of the invention is soft, less prone to fold-creasing, and resistant to deformation.

Brief Description of Drawing [0008]

Fig. 1 is a plan view of an absorbent article, specifically a tape-type disposable diaper 1, comprising an absorbent body according to one embodiment of the present disclosure.

Fig. 2 is a plan view of the absorbent body 3 of the tape-type disposable diaper 1 shown in Fig. 1.

Fig. 3 is a partial cross-sectional view of the absorbent body 3 shown in Fig. 2, along cross-section III-III.

Fig. 4a is a plan view of an absorbent body 3 according to another embodiment of the present disclosure .

Fig. 4b is a plan view of an absorbent body 3 according to another embodiment of the present disclosure .

Fig. 5 is a partial cross-sectional view along cross-section V-V of Fig. 4.

Fig. 6 is a partial cross-sectional view along cross-section VI-VI of Fig. 1.

Fig. 7 is a diagram illustrating a method for producing an absorbent body and absorbent article according to an embodiment of the present disclosure.

Fig. 8 is a diagram illustrating a method of measuring tensile strength. 4

Description of Embodiments [0009] [Definitions] • "Exposed"

As used herein, the term "exposed" as it relates to thermoplastic resin fibers means that the thermoplastic resin fibers are present on the first surface of the absorbent core or the second surface of the absorbent core .

[0010] • "Mean fiber length"

For the purpose of the present disclosure, the mean fiber length for non-pulp thermoplastic resin fibers and cellulosic water-absorbent fibers, such as regenerated cellulose fibers or semisynthetic fibers, is measured according to JIS L 1015:2010, Appendix A, "A7.1 Measurement of Fiber Length", "A7.1.1 Method A (standard method) Method of measuring individual fiber lengths on scaled glass plate".

This method is the test method corresponding to ISO 6989 published in 1981.

[0011] • "Mean fiber length"

For the purpose of the present disclosure, the mean fiber length of pulp is the weight-weighted average fiber length, and it is the L(w) value measured using Kajaani fiber Lab fiber properties (off-line)] by Metso Automation.

[0012]

The absorbent body of the present disclosure, and an absorbent article comprising the absorbent body, will now be described. The absorbent body of the present disclosure will be explained as being incorporated into an absorbent article, as necessary.

[Absorbent body]

The absorbent body of the disclosure is an absorbent 5 body for an absorbent article, having a lengthwise direction and a widthwise direction. The absorbent body comprises an absorbent core with a first surface, and a second surface on opposite side thereof, the absorbent core including thermoplastic resin fibers, cellulosic water-absorbent fibers and a superabsorbent polymer.

Also, in the absorbent body of the disclosure, all or at least some of the thermoplastic resin fibers have a first section exposed on the first surface of the absorbent core, a second section exposed on the second surface of the absorbent core, and a connected section connecting the first section and second section. As used herein, the first section, second section and connected section may be referred to as "specified fiber orientation".

The first surface and second surface of the absorbent core are assumed to be the surface on the wearer side and the surface on the clothing side, respectively.

[0013]

Fig. 1 is a plan view of an absorbent article, specifically a tape-type disposable diaper 1, comprising an absorbent body according to one embodiment of the present disclosure. The front of the tape-type disposable diaper 1 shown in Fig. 1 is the lower side in the drawing. The tape-type disposable diaper 1 shown in Fig. 1 has a top sheet 2 as a liquid-permeable layer, an absorbent body 3, and a liquid-impermeable back sheet 4 as a liquid-impermeable layer.

The tape-type disposable diaper 1 shown in Fig. 1 will now be explained in detail for the locations of the absorbent article discussed below.

[0014]

Fig. 2 is a plan view of the absorbent body 3 of the tape-type disposable diaper 1 shown in Fig. 1, and Fig. 3 is a partial cross-sectional view of the absorbent body 3 shown in Fig. 2, along cross-section III-III.

In Fig. 3, the absorbent body 3 comprises an 6 absorbent core 5, a first core wrap 11 covering the first surface 9 of the absorbent core 5, and a second core wrap 12 covering the second surface 10 of the absorbent core 5. The absorbent core 5 in Fig. 3 includes thermoplastic resin fibers 6, cellulosic water-absorbent fibers 7 and a superabsorbent polymer 8.

[0015]

For explanation in Fig. 3, the thermoplastic resin fibers 6 are drawn thick and long, and the cellulosic water-absorbent fibers 7 are drawn thinner and shorter than the thermoplastic resin fibers 6, but this does not reflect the actual thicknesses and lengths of the fibers.

[0016]

Also in Fig. 3, the thermoplastic resin fibers 6' each have a first section 6'a exposed on the first surface 9 of the absorbent core 5, a second section 6'b exposed on the second surface 10 of the absorbent core 5, and a connected section 6'c connecting the first section 6'a and the second section 6'b. More specifically, the thermoplastic resin fibers 6' have, at one end (the left end in the drawing), a first section 6'a exposed on the first surface 9 of the absorbent core 5, at the other end (the right end in the drawing), a second section 6'b exposed on the second surface 10 of the absorbent core 5, and a connected section 6'c connecting the first section 6'a and the second section 6'b.

[0017]

Also the thermoplastic resin fibers 6'' have, at one end (the left end in the drawing), a first section 6''a exposed on the first surface 9 of the absorbent core 5, a second section 6''b exposed on the second surface 10 of the absorbent core 5, between the one end (the left end) and the other end (the right end) , and a connected section 6''c connecting the first section 6''a and the second section 6''b.

[0018]

The absorbent body 3 shown in Fig. 3 comprises an 7 adhesive section (not shown) between the first surface 9 of the absorbent core 5 and the first core wrap 11, and the first sections 6'a and 6''a of the thermoplastic resin fibers 6' and 6'' are connected to the first core wrap 11 via the adhesive section (not shown). The absorbent body 3 shown in Fig. 3 also comprises an adhesive section (not shown) between the second surface 10 of the absorbent core 5 and the second core wrap 12, and the second sections 6'b and 6''b of the thermoplastic resin fibers 6' and 6'' are connected to the second core wrap 12 via the adhesive section (not shown).

[0019]

The thermoplastic resin fibers 6' and 6'' act as an elastic solid to some extent, so that when the absorbent body 3 (absorbent core 5) is deformed by force applied to the absorbent body 3 (absorbent core 5), the thermoplastic resin fibers 6' and 6'' stretch. When the force applied to the absorbent body 3 (absorbent core 5) is then removed, the stretched thermoplastic resin fibers 6' and 6'' contract, rapidly causing the shape of the absorbent body 3 (absorbent core 5) to be restored. In other words, the thermoplastic resin fibers 6' and 6'' in the absorbent body 3 (absorbent core 5) exhibit recovering force.

[0020]

This recovering force is higher with greater connection of the first sections 6'a and 6''a of the thermoplastic resin fibers 6' and 6'' with the first core wrap 11, and higher with greater connection of the second sections 6'b and 6''b of the thermoplastic resin fibers 6' and 6'' with the second core wrap 12.

This is because some of the thermoplastic resin fibers 6' and 6'' are anchored to the first core wrap 11 and/or second core wrap 12, whereby the thermoplastic resin fibers 6' and 6'' more easily function as an elastic solid.

As a result, the absorbent body 3 (absorbent core 5) - 8 - is less prone to fold-creasing, and is less likely to deform.

[0021]

In the absorbent body of the disclosure, the adhesive sections are formed with an adhesive known in the technical field, without any particular restrictions.

The adhesive can be coated by a coating method, such as spiral coating application, coater application, curtain coater application or summit-gun coating.

[0022]

The absorbent body 3 shown in Fig. 3 comprises an absorbent core 5, a first core wrap 11 covering the first surface 9 of the absorbent core 5, and a second core wrap 12 covering the second surface 10 of the absorbent core 5, but the absorbent body of the disclosure does not need to include a core wrap. That is, the absorbent core may constitute the absorbent body.

In an embodiment in which the absorbent body does not include a core wrap, the absorbent body, i.e. the absorbent core, is preferably connected to the layer adjacent to the wearer side, such as the liquid-permeable layer, via the adhesive section, and/or it is preferably connected to the layer adjacent to the clothing side, such as the liquid-impermeable layer. This is so that the thermoplastic resin fibers having a specified fiber orientation are anchored to the layer adjacent to the wearer side and/or the layer adjacent to the clothing side, and to thus more easily function as an elastic solid.

[0023]

In the absorbent body of the disclosure, the thermoplastic resin fibers having the specified fiber orientation function as a lattice to hold the other components of the absorbent body, such as the cellulosic water-absorbent fibers, and thereby improve the strength of the absorbent body. As a result, when the force of body pressure or the like is applied, the absorbent body - 9 - of the disclosure is less likely to have detachment inside the absorbent body, and the absorbent body becomes more resistant to twisting than an absorbent body not containing the thermoplastic resin fibers, such as an absorbent body containing pulp alone.

[0024]

Moreover, in the absorbent body of the disclosure, the thermoplastic resin fibers having the specified fiber orientation minimize movement of the superabsorbent polymer in the absorbent body, so that loss of the superabsorbent polymer from the absorbent body (absorbent core) is reduced. Consequently, the superabsorbent polymer is less likely to become unintentionally maldistributed, and as a result, the absorbent body will be less likely to be unintentionally expanded after absorption of fluid.

In addition, since the thermoplastic resin fibers in the absorbent body of the disclosure maintain the shape of the absorbent body even when a large amount of fluid has been absorbed, the absorbent body is resistant to deformation or fragmentation into multiple fragments, for example .

[0025]

Furthermore, in the absorbent body of the disclosure, the strength of the absorbent body is increased without being dependent on heat fusion of the thermoplastic resin fibers, and therefore the absorbent body of the disclosure is softer than the absorbent body described in PTL 1, and the person wearing the absorbent article is thus less likely to experience discomfort.

[0026]

From the viewpoint of reduced proneness to fold-creasing, the absorbent body of the disclosure has a folding recovery percentage of preferably 85% or greater, more preferably 88% or greater, even more preferably 90% or greater, and most preferably 92% or greater.

The upper limit for the folding recovery percentage 10 will generally be 100%, but it may even exceed 100%.

[0027]

The folding recovery percentage is measured in the following manner. (1) The absorbent body is cut to a 100 mm length x 50 mm width (lengthwise direction x widthwise direction), to prepare a sample. (2) The initial angle θο of the sample is measured. The initial angle θο (°) is the angle that the inner side, described below, forms at both ends of the folding axis, also described below, before folding. (3) The sample is folded around the axis parallel to the widthwise direction (hereunder referred to as "folding axis"), through the center in the lengthwise direction of the sample, with the side that contacts with the wearer (hereunder referred to as "inner side") on the inside .

[0028] (4) A weight (3.5 kg, base size: 10 cm x 10 cm) is placed on the folded sample and allowed to stand for 1 minute . (5) After standing for 1 minute, the weight is removed and the angle θχ (°) formed by the inner side at both ends of the folding axis is measured 1 minute after removal of the weight. (6) The folding recovery percentage R (%) is calculated by the following formula: R = 100 x θχ/θο (7) This measurement is repeated a total of 5 times with different samples, and the mean value for the measured values is used as the value of the folding recovery percentage.

The measurement is carried out under environmental conditions of 20°C, 65% relative humidity.

[0029]

In the absorbent body of the disclosure, the 11 absorbent core has a bending resistance of preferably 3. ON or less, more preferably 2. ON or less, even more preferably 1.5N or less and yet more preferably 1. ON or less. This is from the viewpoint of the softness of the absorbent core, and therefore the absorbent body.

[0030]

For the purpose of the present specification, the bending resistance is measured in the following manner. The aspects not mentioned here were according to JIS L 1913:2010, "General nonwoven fabric test method", "6.7.4 Gurley method". (1) A No.311 Gurley flexibility tester by Yasuda Seiki Seisakusho Co., Ltd. is prepared in a steady temperature and humidity room at 20°C, 65% RH.

[0031] (2) The sample is cut to a size of 38 mm x 25 mm (lengthwise direction x widthwise direction) to prepare a measuring sample. (3) The sample is set in the Gurley flexibility tester and the bending resistance is measured (1st time). Next, the front and back of the sample are reversed, the sample is set in the Gurley flexibility tester and the bending resistance is measured (2nd time).

The mean value of the two measured bending resistance values is calculated. (4) This measurement is repeated a total of 5 times with different samples, and the mean value for the measured values is used as the bending resistance.

[0032]

For the absorbent body of the present disclosure, the tensile strength in the thickness direction of the absorbent core is preferably 100 Pa or greater, more preferably 150 Pa or greater, even more preferably 200 Pa or greater and yet more preferably 250 Pa or greater. If the tensile strength is less than 100 Pa, the amount of thermoplastic resin fibers of specified fiber orientation 12 will be reduced and the strength of the absorbent core in the thickness direction will be weakened, potentially resulting in twisting of the absorbent core.

[0033]

Furthermore, for the absorbent body of the disclosure, the upper limit of the tensile strength in the thickness direction of the absorbent core is not particularly restricted but is preferably 3000 Pa or less from the viewpoint of softness.

For the absorbent body of the disclosure, the tensile strength of the absorbent body in the thickness direction is also preferably in the range specified above .

[0034]

For the purpose of the present disclosure, the tensile strength is measured as follows, using a device as shown in Fig. 8. (1) A pair of acrylic jigs 401 (diameter: 68 mm, mass of each jig: 200 g, grip section 401a height: 50 mm) is prepared. (2) A sample 402 with a diameter of 68 mm is prepared from the absorbent body. (3) Two strips of double-sided tape 403 (3M Corp., adhesive transfer tape 950) cut out to a diameter of 68 mm are prepared.

[0035] (4) The sample 402 is affixed to the pair of jigs 401 using the two double-sided tape pieces 403, as shown in Fig. 8. (5) The pair of jigs 401 with the sample 402 is placed on a holding stage 405, and a weight 404 (10.5 kg) is set over it and allowed to stand for 3 minutes. (6) The pair of jigs 401 is set in a tensile tester (Shimadzu Corp., AG-1 kNI) with a grip spacing of 70 mm.

[0036] (7) The sample 402 is subjected to a tensile test at a speed of 100 mm/min until the inner layers of the 13 sample 402 detach, and the maximum tensile force (N) at that time is recorded. (8) The measurement is repeated a total of 5 times with different samples, the mean value of the maximum tensile force (N) is determined, and the tensile strength (Pa) is calculated by the following formula:

Tensile strength (Pa) = mean value (N) of maximum tensile force /0.003632 (m2) .

The measurement is conducted under 20°C conditions.

[0037]

In the absorbent body of the disclosure, the thermoplastic resin fibers of specified fiber orientation have a mean fiber length that is preferably 2 times or greater, more preferably 3 times or greater, even more preferably 4 times or greater, yet more preferably 5 times or greater and most preferably 7 times or greater compared to the thickness of the absorbent core (or absorbent body). If it is less than 2 times, the thermoplastic resin fibers will be less able to be exposed on both the first surface of the absorbent core and the second surface of the absorbent core, and it will therefore be difficult to improve the recoverability after folding of the absorbent body.

[0038]

In the absorbent body of the disclosure, the thermoplastic resin fibers of specified fiber orientation have a mean fiber length that is preferably 30 times or less, more preferably 20 times or less and even more preferably 15 times or less the thickness of the absorbent core. If it is greater than 30 times the thickness, opening of the thermoplastic resin fibers will be insufficient and the uniformity of the absorbent core will be inhibited, while it may also be difficult to improve the recoverability after folding of the absorbent body.

[0039]

In the absorbent body of the disclosure, the 14 thermoplastic resin fibers of specified fiber orientation have a mean fiber length of preferably 6 to 70 mm, more preferably 10 to 50 mm and even more preferably 15 to 40 mm. If the mean fiber lengths are less than 6 mm, it will tend to be difficult for the thermoplastic resin fibers to be exposed both on the first surface of the absorbent core and the second surface of the absorbent core, and it will be difficult for the thermoplastic resin fibers to become entangled with the other thermoplastic resin fibers and/or cellulosic water-absorbent fibers, and thus difficult to improve the recoverability after folding of the absorbent body.

By entanglement of the thermoplastic resin fibers with the other fibers, the thermoplastic fibers become anchored and more easily function as an elastic solid, so that the recoverability after folding of the absorbent body is improved.

[0040]

Also, if the mean fiber lengths are greater than 70 mm, the fiber-opening property of the thermoplastic resin fibers will be notably reduced and the absorbent body will include non-opened thermoplastic resin fibers, thus tending to lower the uniformity of the absorbent body and potentially making it difficult to improve the recoverability after folding of the absorbent body.

This mean fiber length range is particularly preferred when the absorbent body of the disclosure is mixed with cellulosic water-absorbent fibers, such as pulp by an airlaid system.

[0041]

In the absorbent body of the disclosure, the thermoplastic resin fibers have a size of preferably 0.5 to 10 dtex and more preferably 1.5 to 5 dtex. If the size is less than 0.5 dtex the fiber-opening property of the thermoplastic resin fibers may be reduced, and if the size exceeds 10 dtex the number of thermoplastic resin fibers will be smaller, tending to reduce the number of 15 entangling points with the other thermoplastic resin fibers and/or cellulosic water-absorbent fibers.

[0042]

The preferred thickness for the absorbent body of the disclosure will differ depending on the purpose of use of the absorbent body, but it will generally be a thickness of 0.1 to 15 mm, preferably 1 to 12 mm and more preferably 2 to 6 mm.

[0043]

As used herein, the thickness (mm) of the absorbent body is that measured in the following manner.

An FS-60DS by Daiei Kagaku Seiki Mfg. Co., Ltd. is prepared [measuring surface: 44 mm (diameter), measuring pressure: 3 g/cm2], five different locations of the absorbent body are pressed under standard conditions (temperature: 23±2°C, relative humidity: 50±5%), the thickness is measured after 10 seconds of pressing at each site, and the mean value of the five measured values is recorded as the thickness of the absorbent body.

[0044]

The absorbent body of the disclosure contains the thermoplastic resin fibers and cellulosic water-absorbent fibers in proportions of preferably 5 to 50 parts by mass and 50 to 95 parts by mass, respectively, and more preferably 10 to 40 parts by mass and 60 to 90 parts by mass, respectively, based on their total of 100 parts by mass. If the proportion of the thermoplastic resin fibers is less than 5 parts by mass, the absolute amount of thermoplastic resin fibers functioning as an elastic solid will be reduced, and the recoverability after folding of the absorbent body may be more difficult to improve as a result. If the proportion of thermoplastic resin fibers is greater than 50 parts by mass, the amount of cellulosic water-absorbent fibers with excellent water absorption will be lower, and the absorption property of the absorbent body will tend to be inadequate.

[0045] 16

The absorbent body of the disclosure has a basis weight of generally 20 to 1000 g/m2, preferably 50 to 800 g/m2 and more preferably 100 to 500 g/m2. This is from the viewpoint of the strength and absorption property of the absorbent body.

[0046]

The absorbent body of the disclosure has a density of preferably 0.06 to 0.14 g/cm3, more preferably 0.07 to 0.12 g/cm3 and even more preferably 0.08 to 0.1 g/cm3. If the absorbent body has the proportions of cellulosic water-absorbent fibers and thermoplastic resin fibers specified above and the density specified above, the absorption property of the absorbent body will tend to be excellent.

The density can be calculated from the basis weight and thickness of the absorbent body.

The basis weight is measured according to JIS L 1913:2010 "6.2 Mass per unit area (ISO method)".

[0047]

Also, from the viewpoint of the strength of connection between the absorbent body and the layer adjacent to the clothing side, such as a liquid-impermeable layer, the absorbent body of the disclosure preferably has a flat surface, for example, a surface without ridge-furrows, on the liquid-impermeable layer side .

[0048]

In the absorbent body of the disclosure, the thermoplastic resin fibers are preferably not fused with the cellulosic water-absorbent fibers and/or other thermoplastic resin fibers. Also in the absorbent body of the disclosure, the thermoplastic resin fibers are preferably entangled with the cellulosic water-absorbent fibers and/or other thermoplastic resin fibers. This is to allow a certain degree of deformation of the absorbent body, so that the wearer experiences a soft feel.

This limitation does not apply to the embossed 17 sections described below.

[0049]

From the viewpoint of the recoverability after folding of the absorbent body, the absorbent body according to another embodiment of the disclosure has a plurality of embossed sections that are formed by embossing at least the absorbent core, and are situated with spacings.

[0050]

Fig. 4(a) is a plan view of an absorbent body 3 according to another embodiment of the disclosure, and Fig. 5 is a partial cross-sectional view along cross-section V-V of Fig. 4(a). The absorbent body 3 shown in Fig. 4(a) and Fig. 5 is identical to the absorbent body 3 shown in Fig. 2 and Fig. 3 except that it has a plurality of dotted embossed sections 21 formed by embossing the absorbent core 5, the first core wrap 11 covering the first surface 9 of the absorbent core 5, and the second core wrap 12 covering the second surface 10 of the absorbent core 5, and disposed at spacings.

[0051]

As shown in Fig. 5, one section of each of the thermoplastic resin fibers 6, 6', 6'' and 6''' is incorporated in the embossed sections 21, and the thermoplastic resin fibers 6, 6', 6'' and 6''' are connected through the embossed sections 21. Thus, the absorbent body 3 essentially includes thermoplastic resin fibers actually having longer mean fiber lengths, the thermoplastic resin fibers 6, 6', 6'' and 6''' also functioning as an elastic solid to further improve the folding recoverability of the absorbent body.

In addition, from the viewpoint of partially anchoring the thermoplastic resin fibers 6, 6', 6'' and 6''' with the embossed sections 21, the thermoplastic resin fibers 6, 6', 6'' and 6''' further function as an elastic solid and further improve the folding recoverability of the absorbent body. 18 [0052]

When the absorbent body of the disclosure has a plurality of embossed sections, the thermoplastic resin fibers in the embossed sections may be either fused or unfused with the other fibers, but they are preferably fused. This is because the effect described above will be more easily obtained by fusing the thermoplastic resin fibers with the other fibers, and especially the other heat-sealable fibers.

[0053]

When the absorbent body of the disclosure has a plurality of embossed sections, the thermoplastic resin fibers are preferably not fused with the cellulosic water-absorbent fibers and/or the other thermoplastic resin fibers at the non-embossed sections, where there is no embossing. This is because the absorbent body will tend to be hard.

[0054]

When the absorbent body of the disclosure has a plurality of embossed sections, the area ratio of the plurality of embossed sections with respect to the area of the absorbent body is preferably 1 to 20%, more preferably 2 to 15% and even more preferably 3 to 10%.

If the area ratio is less than 1% the effect of the embossed sections will tend to be less apparent, and if the area ratio is greater than 10% the wearer will tend to feel the hardness of the absorbent body.

The terms "area of the absorbent body" and "area of the embossed sections" refer to the area when viewing the plane of the absorbent body.

[0055]

When the absorbent body of the disclosure has a plurality of embossed sections, the shapes of the embossed sections are not particularly restricted, and the embossed sections may be dotted embossed sections or linear embossed sections. Examples of dotted embossed sections include circular, elliptical, rectangular, 19 triangular, star-shaped and heart-shaped embossed sections .

There are no particular restrictions on the placement of the embossed sections, and for example, it may be in a zigzag fashion, such as in a square zigzag or 60° zigzag placement.

[0056]

When the absorbent body of the disclosure has a plurality of embossed sections, the spacing between the embossed sections is preferably 2.0 times or less the mean fiber length of the thermoplastic resin fibers, more preferably 1.0 times or less the mean fiber length of the thermoplastic resin fibers, even more preferably 0.7 times or less the mean fiber length of the thermoplastic resin fibers and yet more preferably 0.5 times or less the mean fiber length of the thermoplastic resin fibers. If the spacing is longer than 2.0 times the mean fiber length of the thermoplastic resin fibers, thermoplastic resin fibers anchored to different embossed sections will not become entangled and it will be difficult to improve the folding recoverability of the absorbent body. Also, if the spacing is 0.5 times or less the mean fiber length of the thermoplastic resin fibers, one thermoplastic resin fiber may become anchored to multiple embossed sections, thus helping to improve the recoverability after folding of the absorbent body.

[0057]

When the absorbent body of the present disclosure has a plurality of embossed sections, the area of each individual embossed section is preferably 0.1 to 20.0 mm2, more preferably 1.0 to 15.0 mm2 and even more preferably 2.0 to 10.0 mm2. If the area is less than 0.1 mm2 the forms of the tips of the protrusions of the embossing roll will be acute angles during formation of the embossed sections, and the absorbent body may be torn, while if the area is greater than 20.0 mm2 the absorbent body will tend to become hard. 20 [0058]

In the absorbent body of the disclosure, the dotted embossed sections shown in Fig. 4(a) are preferably formed by pressing punctiform protrusions onto the wearer side of the absorbent body, i.e. the first surface side of the absorbent core. This is because the absorbent body will more easily follow the line of the wearer's body if the absorbent body has the dotted embossed sections formed from the wearer side surface.

The specific method of forming the embossed sections will be explained below under "Production method".

[0059]

Fig. 4(b) is a plan view of an absorbent body according to another embodiment of the disclosure. The absorbent body 3 shown in Fig. 4(b) has a plurality of linear embossed sections 21 formed by embossing the absorbent core 5, the first core wrap 11 covering the first surface 9 of the absorbent core 5, and the second core wrap 12 covering the second surface 10 of the absorbent core 5, and disposed at spacings. The linear embossed sections 21 extend in the lengthwise direction of the absorbent body 3.

[0060]

In the absorbent body of the present disclosure, the linear embossed sections shown in Fig. 4(b) are preferably formed by pressing linear protrusions onto the clothing side of the absorbent body, i.e. the second surface side of the absorbent core. This is because the absorbent body will be more easily restored when it has bent in the direction of the wearer, if the absorbent body has the linear embossed sections formed from the clothing side surface.

[0061]

In the embodiments illustrated in Fig. 4(a), Fig. 4(b) and Fig. 5, the embossed sections 21 are formed by 21 embossing of the absorbent core 5, the first core wrap 11 and the second core wrap 12, but in an absorbent body according to another embodiment of the disclosure, the embossed sections are formed by embossing only the absorbent core. This will help prevent the wearer from feeling the hardness of the embossed sections in an embodiment wherein the absorbent body includes a core wrap.

[0062]

In an embodiment wherein the absorbent body of the disclosure includes a first core wrap and a second core wrap, the first core wrap and second core wrap may be continuous, or in other words, the first core wrap and second core wrap may be formed from a single sheet. Alternatively, the first core wrap and second core wrap may be discontinuous, or in other words, the first core wrap and second core wrap may be formed from different sheets .

[0063]

The thermoplastic resin fibers may be ones containing only a single component, such as simple fibers, or ones containing multiple components, such as composite fibers. Such components include polyolefins such as polyethylene, polypropylene, polybutylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer and ionomer resins; polyesters, such as polyethylene terephthalate (PET) , polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT) and polylactic acid; and polyamides such as nylon.

[0064]

Examples of the composite fibers include composite fibers, such as core-sheath fibers, side-by-side fibers and sea/island fibers; and hollow type fibers; irregularly shaped fibers, such as flat fibers, Y-shaped fibers or C-shaped fibers; solid crimped fibers, such as latent crimped or developed crimped fibers, and split 22 fibers that have been split by a physical load, such as a water stream, heat, embossing or the like, preferred among which are core-sheath fibers and especially PET/PE and PP/PE (core/sheath) , which are industrially economical and highly safe.

[0065]

The mass ratio of the core component/sheath component is preferably 10/90 to 90/10 and more preferably 30/70 to 70/30. If the sheath component proportion is low the fusibility will be reduced, and if the sheath component proportion increases, the spinnability will tend to be reduced.

[0066]

Cellulosic water-absorbent fibers may be pulp, such as wood pulp obtained using a conifer or broadleaf tree as a starting material, or nonwood pulp, such as bagasse, kenaf, bamboo, hemp, cotton (for example, cotton linter); regenerated cellulose fiber, such as rayon fiber, or semisynthetic fiber, such as acetate fiber. The pulp is preferably Kraft pulp which is industrially economical and highly safe.

[0067]

The mean fiber lengths of the cellulosic water-absorbent fibers are not particularly restricted. When the cellulosic water-absorbent fibers are regenerated cellulose fibers or semisynthetic fibers, they may have mean fiber lengths of 3 to 70 mm, 5 to 50 mm or 10 to 40 mm. The regenerated cellulose fibers or semisynthetic fibers have the same function as thermoplastic resin fibers when dry, depending on their fiber lengths, and can provide the absorbent body with folding recoverability.

[0068]

The absorbent body of the disclosure includes the superabsorbent polymer at preferably a range of 5 to 80 mass%, more preferably 10 to 60 mass% and even more preferably 20 to 40 mass% of the total mass of the 23 absorbent core.

Examples of the superabsorbent polymers include starch-based, cellulosic and synthetic polymer-based, such as acrylic acid-based superabsorbent polymers.

[0069]

An absorbent body according to another embodiment of the disclosure has the following construction.

An absorbent body for an absorbent article, the absorbent body comprising an absorbent core, the absorbent core including thermoplastic resin fibers, cellulosic water-absorbent fibers and a superabsorbent polymer, the thermoplastic resin fibers having a mean fiber length of 6 to 70 mm, and the absorbent body having a folding recovery percentage of 85% or greater.

Each aspect of this construction is as described above.

[0070] [Absorbent article]

The absorbent article of the disclosure comprises a liquid-permeable layer, a liquid-impermeable layer, and an absorbent body formed between the liquid-permeable layer and the liquid-impermeable layer, and the absorbent core has the first surface of the absorbent core facing the liquid-permeable layer side, and the second surface of the absorbent core facing the liquid-impermeable layer .

The absorbent body in the absorbent article of the disclosure is as follows.

In the absorbent article of the disclosure, the cellulosic water-absorbent fibers contained in the absorbent body are associated with the absorption property and fluid retention of the absorbent body while the thermoplastic resin fibers in the absorbent body are associated with connection between the liquid-permeable layer and/or liquid-impermeable layer, and especially the liquid-impermeable layer, and this imparts recoverability after folding of the absorbent article while also 24 imparting softness to the absorbent body and therefore to the absorbent article.

[0071]

Fig. 1 is a plan view of an absorbent article, specifically a tape-type disposable diaper 1, comprising an absorbent body according to one embodiment of the disclosure, and Fig. 6 is a partial cross-sectional view along cross-section VI-VI in Fig. 1. The front of the tape-type disposable diaper 1 shown in Fig. 1 is the lower side in the drawing. The tape-type disposable diaper 1 shown in Fig. 1 has a top sheet 2 as a liquid-permeable layer, an absorbent body 3, and a back sheet 4 as a liquid-impermeable layer. The absorbent body 3 is identical to the one shown in Fig. 3. Also, the tape-type disposable diaper 1 shown in Fig. 1 has a pair of leakage preventing gathers 41 including an expandable and shrinkable member 41a, and a fastener 42. In Fig. 1 there are also shown a pair of expandable and shrinkable members 42 situated between the sheet composing the leakage preventing gathers 41, and the back sheet 4.

[0072]

The tape-type disposable diaper 1 shown in Fig. 6 has an adhesive section (not shown) between the top sheet 2 and the absorbent body 3 to connect the top sheet 2 and absorbent body 3, and an adhesive section (not shown) between the absorbent body 3 and the back sheet 4 to connect the absorbent body 3 and back sheet 4.

[0073]

In the tape-type disposable diaper 1 shown in Fig. 6, first sections 6'a and 6''a of thermoplastic resin fibers 6' and 6'' are connected to the top sheet 2 via adhesive sections (not shown) and the first core wrap 11, while second sections 6'b and 6''b of thermoplastic resin fibers 6' and 6'' are anchored to the back sheet 4 via adhesive sections (not shown) and the second core wrap 12. As a result, interlayer separation is unlikely to occur between the absorbent body 3 and top sheet 2 or 25 between the absorbent body 3 and the back sheet 4, and the tape-type disposable diaper 1 is unlikely to twist. Furthermore, the thermoplastic resin fibers 6' and 6'' connected to the top sheet 2 and the back sheet 4 function as an elastic solid, and the tape-type disposable diaper 1 has excellent recoverability after folding.

[0074]

In an embodiment of the absorbent article of the disclosure in which the absorbent body has linear embossed sections, the linear embossed sections are preferably formed by pressing linear projections from the second surface side of the absorbent core. This is because recovery will be facilitated when the absorbent body is bent in the direction of the wearer.

In an embodiment of the absorbent article of the disclosure in which the absorbent body has dotted embossed sections, the dotted embossed sections are preferably formed by pressing punctiform projections from the first surface side of the absorbent core. This is to help the absorbent body more easily follow the body line of the wearer.

[0075] [Production method]

The absorbent body of the disclosure may be produced by any method without any particular restrictions so long as it can produce a body including thermoplastic resin fibers and cellulosic water-absorbent fibers, wherein at least some of the thermoplastic resin fibers have a first section exposed on the first surface of the absorbent core and a second section exposed on the second surface of the absorbent core, and any method known in the technical field may be utilized. The absorbent article of the disclosure may also be produced by a method known in the technical field, except that it contains the absorbent body described above. A production example for the absorbent article of 26 the disclosure will now be explained.

[0076]

Fig. 7 is a diagram illustrating a method for producing an absorbent body and an absorbent article according to an embodiment of the disclosure. The method illustrated in Fig. 7 comprises a first step (I) and a second step (II).

Incidentally, the thermoplastic resin fibers and cellulosic water-absorbent fibers are not shown separately in Fig. 7.

[0077] [First step (1)] A plurality of recesses 153 are formed at a prescribed pitch on the peripheral surface 151a of a suction drum 151 rotating in the machine direction MD, extending from the peripheral surface 151a toward the center of the suction drum, as a molding form in which the absorbent body material is to be packed. When the suction drum 151 is rotated and the recesses 153 approach the material feeder 152, the suction action of the suction section 156 causes the absorbent body material supplied from the material feeder 152 to accumulate in the recesses 153.

[0078]

The material feeder 152, equipped with a hood 152a, is formed so as to cover the suction drum 151, and the material feeder 152 supplies a mixture 21 comprising cellulosic water-absorbent fibers and thermoplastic resin fibers into the recesses 153 by air transport. The material feeder 152 is also provided with a particle feeder 158 that supplies superabsorbent polymer particles 22, so that superabsorbent polymer particles 22 are supplied to the recesses 153. The mixture 21 of the cellulosic water-absorbent fibers and thermoplastic resin fibers and the superabsorbent polymer particles 22 (hereunder referred to as "absorbent body starting material") accumulates in the recesses 153 in a mixed 27 state, and an absorbent body 226 is formed in the recesses 153.

[0079]

In order for at least some of the thermoplastic resin fibers to have the specified fiber orientation, the hood 152a of the material feeder 152 has an accumulation space 152b that is larger than hoods generally used in the technical field, at the downstream end in the machine direction MD (upstream from accumulation of the absorbent body starting material).

[0080]

This will tend to cause the thermoplastic resin fibers to accumulate in the depthwise direction of the recesses 153, or in other words, in the direction from the peripheral surface 151a of the suction drum 151 toward the center.

As regards the absorbent body starting material and the recesses 153, the absorbent body starting material tends to accumulate in order from the recess section 153a of the recess at the downstream end of rotation of the suction drum toward the recess section 153b at the upstream end of rotation, and therefore the thermoplastic resin fibers tend to have the aforementioned specified fiber orientation.

[0081]

In addition, during accumulation of the absorbent body starting material in the recesses 153, the thermoplastic resin fibers can be easily given the aforementioned specified fiber orientation by increasing the suction force of the suction drum upstream from accumulation of the absorbent body starting material, so that it is greater than downstream from accumulation of the absorbent body starting material.

Furthermore, if the rotational speed of the suction drum is slower than the rate of flow of the absorbent body starting material, the thermoplastic resin fibers will more easily adopt the aforementioned specified fiber 28 orientation .

Next, the absorbent body 226 formed in the recesses 153 is transported onto a carrier sheet 150 having an adhesive coated by a coating machine 159.

[0082]

The carrier sheet 150 later forms a second core wrap, but in an embodiment where the absorbent article does not have a core wrap, the liquid-permeable layer, the liquid-impermeable layer or an optional auxiliary sheet or the like may be used as the carrier sheet.

Next, the first core wrap sheet 228 is supplied from a roll 227, and the first core wrap sheet 228 is coated with an adhesive coated from a coating machine 229, after which it is stacked on the absorbent body 226 to form a stacked body 230.

[0083] [Second step (II)]

In the embossing step of the second step (II), the stacked body 230 is embossed using a pair of embossing rolls 301, 302, to form embossed sections in the stacked body 230. In the subsequent cutting step, a pair of rolls 303, 304 is used to punch a prescribed shape in the stacked body 230 to produce an absorbent body 305. The other steps are omitted from this explanation since they are carried out by known methods.

[0084]

The temperature of the embossing rolls during the embossing step is preferably in a prescribed relationship, above the melting point of the thermoplastic resin fibers composing the absorbent body. Specifically, the temperature may be a temperature at which some of the thermoplastic resin fibers melt, and for example, when the thermoplastic resin fibers are sheath/core composite fibers, the temperature may be a temperature at or above the temperature at which partial melting of the sheath component begins.

[0085] 29

The temperature of the embossing rolls in the embossing step will usually be 30 to 160°C and preferably 30 to 140°C, the pressure will usually be 10 to 3000 N/mm and preferably 50 to 500 N/mm, and the processing time will usually be 0.0001 to 5 seconds and preferably 0.005 to 2 seconds.

Examples [0086]

The invention will now be further explained by examples, with the understanding that the invention is not limited to the examples.

[Production Example 1]

The apparatus illustrated in Fig. 7 was used to obtain an absorbent core with unadjusted thickness, having a size of 340 mm length x 110 mm width, including in terms of basis weight, pulp: 225 g/m2, thermoplastic resin fibers: 25 g/m2, and sodium polyacrylate-based superabsorbent polymer (SAP): 220 g/m2. The thermoplastic resin fibers were core-sheath fibers with a core of polyethylene terephthalate and a sheath of polyethylene, and having a mean fiber length of 30 mm and a size of 2.2 dtex.

Next, the absorbent core with unadjusted thickness was passed through a pair of flat rolls to adjust its thickness and produce absorbent core No.l.

[0087] [Production Examples 2 to 6]

Absorbent core Nos. 2 to 6 were produced by the same procedure of Production Example 1, except that the proportion of thermoplastic resin fibers and pulp were changed as shown in Table 1.

[0088] [Examples 1 to 5 and Comparative Example 1]

The folding recovery percentages of absorbent cores No.l to No.6 were evaluated. The results are summarized 30 in Table 1.

The tensile strengths of absorbent cores No.l to No.5 of Examples 1 to 5 in the thickness direction were 100 Pa or greater. 5 [0089]

Table 1

Example No. Absorbent core No. Absorbent core thickness (mm) Absorbent body basis weight (g/m2) Thermoplastic resin fiber basis weight (g/m2) Pulp basis weight (g/m2) SAP basis weight (g/m2) Folding recovery percentage (%) Example 1 1 4.72 470 25 225 220 94 Example 2 2 4.38 470 50 200 220 94 Example 3 3 4.89 470 87 163 220 94 Example 4 4 4.50 470 125 125 220 97 Example 5 5 4.86 470 163 87 220 97 Comp . Example 1 6 5.05 470 0 250 220 83 32

Reference Signs List [0090] 1 Tape-type disposable diaper 2 Top sheet 3 Absorbent body 4 Back sheet 5 Absorbent core 6 Thermoplastic resin fiber 6a First section 6b Second section 6c Connected section 7 Cellulosic water-absorbent fiber 8 Superabsorbent polymer 9 First surface 10 Second surface 11 First core wrap 12 Second core wrap 21 Embossed section 41 Leakage preventing gather 41a, 43 Expandable and shrinkable members 42 Fastener 401 Jig 4 02 S amp1e 403 Double-sided tape 404 Weight 405 Holding stage

Claims

CLAIMS Claim 1. An absorbent body for an absorbent article having a lengthwise direction and a widthwise direction, wherein the absorbent body comprises an absorbent core having a first surface and a second surface on opposite side thereof, the absorbent core includes thermoplastic resin fibers, cellulosic water-absorbent fibers and a superabsorbent polymer, at least some of the thermoplastic resin fibers have a first section exposed on the first surface of the absorbent core, a second section exposed on the second surface of the absorbent core, and a connected section connecting the first section and second section, and the absorbent body has a folding recovery percentage of 85% or greater.
Claim 2. The absorbent body according to claim 1, wherein the absorbent body further comprises a first core wrap covering the first surface of the absorbent core and an adhesive section between the first surface of the absorbent core and the first core wrap, the first sections of the thermoplastic resin fibers being connected to the first core wrap via the adhesive section, and/or the absorbent body further comprises a second core wrap covering the second surface of the absorbent core and an adhesive section between the second surface of the absorbent core and the second core wrap, the second sections of the thermoplastic resin fibers being connected to the second core wrap via the adhesive section .
Claim 3. The absorbent body according to claim 1 or 2, wherein the thermoplastic resin fibers have mean fiber length that is at least two times the thickness of the absorbent core.
Claim 4. The absorbent body according to any one of claims 1 to 3, wherein the thermoplastic resin fibers have a mean fiber length of 6 to 70 mm.
Claim 5. The absorbent body according to any one of claims 1 to 4, wherein the absorbent body has a plurality of embossed sections that are formed by embossing at least the absorbent core, and are situated with spacings.
Claim 6. The absorbent body according to claim 5, wherein the embossed sections include linear embossed sections that extend in the lengthwise direction.
Claim 7. The absorbent body according to claim 6, wherein the linear embossed sections are formed by pressing linear projections onto at least the absorbent core from the second surface side of the absorbent core.
Claim 8. The absorbent body according to any one of claims 5 to 7, wherein the embossed sections include dotted embossed sections.
Claim 9. The absorbent body according to claim 8, wherein the dotted embossed sections are formed by pressing punctiform projections onto at least the absorbent core from the first surface side of the absorbent core.
Claim 10. The absorbent body according to any one of claims 5 to 9, wherein the spacings are 2.0 times or less the mean fiber length of the thermoplastic resin fibers.
Claim 11. The absorbent body according to any one of claims 5 to 10, wherein the thermoplastic resin fibers are not fused with the cellulosic water-absorbent fibers and/or other thermoplastic resin fibers at a non-embossed section, which has no embossing.
Claim 12. The absorbent body according to any one of claims 1 to 11, wherein the absorbent core includes the thermoplastic resin fibers and cellulosic water-absorbent fibers in proportions of 5 to 50 parts by mass and 50 to 95 parts by mass, respectively, based on their total of 100 parts by mass.
Claim 13. The absorbent body according to any one of claims 1 to 12, wherein a tensile strength of the absorbent core in the thickness direction is 100 Pa or greater.
Claim 14. An absorbent article comprising a liquid-permeable layer, a liquid-impermeable layer, and the absorbent body according to any one of claims 1 to 13 provided between the liquid-permeable layer and the liquid-impermeable layer, wherein the absorbent core is disposed with the first surface facing the liquid-permeable layer and the second surface facing the liquid-impermeable layer.
Claim 15. An absorbent body for an absorbent article, the absorbent body comprising an absorbent core, the absorbent core including thermoplastic resin fibers, cellulosic water-absorbent fibers and a superabsorbent polymer, wherein the thermoplastic resin fibers have a mean fiber length of 6 to 70 mm, and the absorbent body has a folding recovery percentage of 85% or greater.