CN113518716B

CN113518716B - Absorbent sheet, disposable wearing article, and method for producing same

Info

Publication number: CN113518716B
Application number: CN202080018294.4A
Authority: CN
Inventors: 冈田友记; 古川勉
Original assignee: Daio Paper Corp
Current assignee: Daio Paper Corp
Priority date: 2019-03-22
Filing date: 2020-01-27
Publication date: 2024-04-02
Anticipated expiration: 2040-01-27
Also published as: TWI805894B; WO2020195096A1; TW202034881A; JP2020151352A; CN113518716A

Abstract

The present invention provides an absorbent sheet having excellent air permeability for releasing moisture and air permeability for effectively supplying moisture to an absorbent material, a disposable wearing article, and a method for manufacturing the same. The above object is achieved by an absorbent sheet (15), wherein the absorbent sheet (15) comprises: a nonwoven fabric (16) in which thin wall parts (16 t) that shrink in the thickness direction are repeatedly formed at intervals; and microfibrous cellulose aggregates (17) which are adhered to the inside of the thin wall portion (16 t).

Description

Absorbent sheet, disposable wearing article, and method for producing same

Technical Field

The present invention relates to an absorbent sheet, a disposable wearing article, and a method for producing the same.

Background

For disposable wearing articles such as disposable diapers and sanitary napkins, a proposal of having hygroscopicity has been made for various reasons.

For example, disposable wearing articles such as disposable diapers and sanitary napkins have an absorber that absorbs excretory fluid such as urine and a liquid-impermeable resin film that covers the back side of the absorber, and in order to prevent stuffiness during wearing, a material having a moisture permeability in the thickness direction is used as the liquid-impermeable resin film (for example, refer to patent documents 1 and 2). In many absorbent articles, the back side of the liquid-impermeable resin film is also covered with a nonwoven fabric for exterior coating in order to give the product an outer surface of the product a cloth-like feel and appearance (for example, refer to patent document 2).

However, in the conventional absorbent article, in order to prevent stuffiness, the liquid impermeable resin film has high moisture permeability, and is damaged by this, and after the absorbent body absorbs excreta liquid, moisture is retained on the outer surface of the product or in the underwear, and leakage may be erroneously considered to occur when the absorbent article is touched by hand.

This problem can be solved by reducing the moisture permeability of the liquid impermeable resin film, but in this case, the reduction of the heat resistance is unavoidable. For this reason, for example, a method of providing a moisture-absorbing layer in a liquid-impermeable resin film or an exterior nonwoven fabric has been proposed (for example, refer to patent document 1).

Further, it is known that disposable wearing articles generally lack breathability, and therefore the interior of the disposable wearing article tends to be stuffy when worn, and in order to prevent this, it has been proposed to attach an absorbent sheet (for example, refer to patent document 3).

In addition, an absorbent sheet may be used as a product packaging material or in a product package (for example, refer to patent document 4).

However, the performance of the absorbent material is of course important, and the air permeability for releasing moisture and the air permeability for supplying moisture to the absorbent material are also important, and from this point of view, there is room for improvement in the conventional absorbent sheet.

Prior art literature

Patent literature

Patent document 1: japanese patent No. 6442098

Patent document 2: japanese patent application laid-open No. 2017-144174

Patent document 3: japanese patent application laid-open No. 2010-279021

Patent document 4: japanese patent application laid-open No. 2010-279806

Disclosure of Invention

Problems to be solved by the invention

Accordingly, a main object of the present invention is to provide an absorbent sheet, a disposable wearing article, and a method for manufacturing the same, which are excellent in breathability for releasing moisture and breathability for effectively supplying moisture to an absorbent material.

Means for solving the problems

The absorbent sheet and the like which solve the above problems are as follows.

< mode 1 >

An absorbent sheet comprising:

a nonwoven fabric in which thin wall portions that shrink in the thickness direction are repeatedly formed at intervals; and

and microfibrous cellulose aggregates attached to the thin wall portion.

(effects of action)

The absorbent sheet is characterized in that a nonwoven fabric having thin portions repeatedly formed at intervals is used as a base, and microfibrous cellulose aggregates having high hygroscopicity are adhered to the thin portions. Therefore, even if the absorbent sheet is used while being sandwiched between objects or members, an air-permeable gap is formed between the objects or members and the thin wall portion of the absorbent sheet. Therefore, in the present absorbent sheet, moisture can be released along the surface of the absorbent sheet through the ventilation gap. In addition, in this process, moisture can be efficiently supplied to the microfibrous cellulose aggregates as the moisture absorbing material to perform moisture absorption. The absorbent sheet may be used alone or as a component of a disposable wearing article as described later.

< mode 2 >

The absorbent sheet according to claim 1, wherein the microfibrous cellulose aggregates are not present except for the thin wall portion.

(effects of action)

Microfibrous cellulose aggregates are rigid. Therefore, the absorbent sheet preferably has microfibrous cellulose aggregates attached only to the thin wall portion. Thus, the portion of the absorbent sheet other than the thin portion can be deformed flexibly, and the user or the wearer does not easily touch the hard thin portion or the hardness thereof is not easily transferred to the skin.

< mode 3 >

The absorbent sheet according to claim 1 or 2, wherein the thin portions are provided in a stripe or lattice shape.

(effects of action)

If the thin portions are provided in a stripe or lattice shape, the continuity of the ventilation gap is improved. Therefore, the air permeability for releasing moisture, and the air permeability for effectively supplying moisture to the moisture absorbent material are more excellent.

< mode 4 >

The absorbent sheet according to any one of modes 1 and 2, wherein the nonwoven fabric constituting the absorbent sheet has a fineness of 2 to 10dtex and a basis weight of 20 to 40g/m ² Is a non-woven fabric of short fibers of (3),

the amount of the microfibrous cellulose aggregates attached to the thin portion is 0.1 to 5.0g/m ² 。

(effects of action)

The nonwoven fabric constituting the absorbent sheet is not particularly limited, but is preferably a nonwoven fabric having excellent bulk and shape-forming properties, and thus is preferably within the above-mentioned range. In addition, in order to improve hygroscopicity, the more the amount of the microfibrous cellulose aggregates attached, the better, but if it is too much, the product becomes unnecessarily hard. Therefore, the content of the microfibrous cellulose aggregates in the thin-walled portion is preferably within the above range.

< mode 5 >

A disposable wearing article comprising:

an absorber;

a liquid-impermeable resin film provided on the back side of the absorber and having air permeability; and

an exterior nonwoven fabric covering the back surface of the liquid-impermeable resin film,

the disposable wearing article is characterized in that,

comprises a moisture-absorbing sheet provided between the liquid-impermeable resin film and the exterior nonwoven fabric,

the absorbent sheet comprises: a nonwoven fabric in which thin wall portions that shrink in the thickness direction are repeatedly formed at intervals; and microfibrous cellulose aggregates attached to the thin wall portion,

and ventilation gaps are respectively arranged between the outer non-woven fabric and the thin wall part and between the liquid impermeable resin film and the thin wall part.

(effects of action)

In the disposable wearing article, the air-permeable gap is formed by interposing the absorbent sheet according to embodiment 1 between the liquid-impermeable resin film and the exterior nonwoven fabric. Therefore, according to the disposable wearing article, the moisture discharged from the liquid impermeable resin film, which is increased after absorption of the excreted liquid, can be absorbed efficiently by the absorbent sheet, and the outer surface of the product or the underwear is less likely to have a wet touch.

< mode 6 >

A disposable wearing article comprising:

a skin contact layer which is in contact with the skin of the wearer and is breathable; and

an absorbent sheet provided so as to have a portion adjacent to the back side of the skin contact layer,

an air-permeable gap is provided between the skin contact layer and the thin-walled portion.

(effects of action)

In order to prevent stuffiness during wearing, the disposable wearing article is provided with a moisture-absorbing sheet so as to have a portion adjacent to the back side of the skin contact layer. Thus, moisture in the disposable wearing article during wearing is effectively absorbed or released to the outside, whereby stuffiness can be prevented.

< mode 7 >

A method for manufacturing a disposable wearing article, comprising the steps of:

a step of applying a dispersion of microfibrous cellulose to a nonwoven fabric at intervals in a repeating pattern, and drying the dispersion to produce an absorbent sheet having thin wall portions formed in the applied portions of the dispersion and microfibrous cellulose aggregates formed in the thin wall portions; and

and a step of manufacturing a disposable wearing article having an air-permeable gap between the member and the thin portion by attaching the absorbent sheet between members overlapping in the thickness direction of the disposable wearing article.

(effects of action)

If the dispersion of the coating portion is dried after the dispersion of the microfibrous cellulose is coated on the nonwoven fabric, the volume of the microfibrous cellulose aggregates gradually decreases when the microfibrous cellulose aggregates are formed. In addition, the volume of the coating portion of the dispersion liquid of the nonwoven fabric is also reduced, and the thin wall portion is automatically formed. The present manufacturing method takes advantage of this.

For example, although the thin portion may be formed on the nonwoven fabric to be the absorbent sheet by embossing and the microfibrous cellulose aggregates may be attached to the thin portion at the same time or later, according to the present production method, the absorbent sheet can be formed by merely applying the microfibrous cellulose dispersion to the nonwoven fabric to be the absorbent sheet in a desired pattern and drying the same.

In addition, if the dispersion liquid of microfibrous cellulose is applied to a nonwoven fabric and then bonded to other members of a disposable wearing article before drying (i.e., before forming the thin wall portion), there is a possibility that formation of the ventilation gap is insufficient. In contrast, in the present manufacturing method, since the disposable wearing article is manufactured using the dried absorbent sheet, a good ventilation gap can be formed. Therefore, the present manufacturing method attaches the cover layer after forming the thin wall portion.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, there can be brought about advantages such as excellent air permeability for releasing moisture, excellent air permeability for effectively supplying moisture to the moisture absorbent material, and the like.

Drawings

Fig. 1 is a plan view showing an inner surface of a tape type disposable diaper in a state in which the diaper is unfolded.

Fig. 2 is a plan view showing an outer surface of a tape type disposable diaper in a state in which the diaper is unfolded.

Fig. 3 is a cross-sectional view taken along line 6-6 of fig. 1.

Fig. 4 is a cross-sectional view taken along line 7-7 of fig. 1.

Fig. 5 is a cross-sectional view taken along line 8-8 of fig. 1.

Fig. 6 is a cross-sectional view taken along line 9-9 of fig. 1.

Fig. 7 is a cross-sectional view taken along line 5-5 of fig. 1.

Fig. 8 is a plan view showing a main portion in a state where the diaper is unfolded.

Fig. 9 is a plan view showing a main portion in a state where the diaper is unfolded.

Fig. 10 is a plan view showing a main portion in a state where the diaper is unfolded.

Fig. 11 is a sectional view showing the absorbent sheet in an enlarged manner.

Fig. 12 is a plan view showing various patterns of the thin wall portion (attached portion of microfibrous cellulose).

Detailed Description

Fig. 1 to 7 show an example of a tape type disposable diaper, in which reference symbol W denotes the entire width of the diaper except for the connecting tape, reference symbol L denotes the entire length of the diaper, and dot pattern portions in the cross-sectional view denote adhesives as joining means for joining the respective constituent members located on the front and rear sides thereof, and are formed by whole-surface coating, droplet coating, curtain coating, summit coating, spiral coating, pattern coating (transfer of a hot melt adhesive by a relief method), or the like of the hot melt adhesive, or by coating the outer peripheral surface of the elastic member in place of or together with the adhesive by a coating gun (comb gun) or SureWrap coating, or the like. Examples of the hot melt adhesive include EVA adhesives, adhesive rubber adhesives (elastic adhesives), olefin adhesives, polyester and polyamide adhesives, and the like, and the hot melt adhesive is not particularly limited. As a joining means for joining the constituent members, a means based on welding of raw materials such as heat sealing or ultrasonic sealing may be employed.

The tape type disposable diaper comprises: an absorber 56; a liquid-permeable top sheet 30 covering the front side of the absorber 56; a liquid-impermeable resin film 11 covering the back side of the absorber 56; and an exterior nonwoven fabric 12 covering the back side of the liquid-impermeable resin film 11 and constituting the outer surface of the product. Reference character F denotes a ventral portion located closer to the front side than the front-rear direction center, and reference character B denotes a dorsal portion located closer to the rear side than the front-rear direction center.

Hereinafter, the materials and the characteristic parts of each part will be described in order.

(absorber)

The absorber 56 is a portion that absorbs and retains excreted liquid, and may be formed of an aggregate of fibers. As the fiber aggregate, a fiber aggregate obtained by fiber-opening tows (fiber bundles) of synthetic fibers such as cellulose acetate, if necessary, may be used in addition to a fiber aggregate obtained by fiber-stacking short fibers such as cotton pulp or synthetic fibers. When cotton pulp or short fibers are fiber-deposited, the fiber basis weight may be, for example, 100 to 300g/m ² About, in the case of a fibril aggregate, it may be, for example, 30 to 120g/m ² Left and right. The fineness of the synthetic fibers is, for example, 1 to 16dtex, preferably 1 to 10dtex, and more preferably 1 to 5dtex. In the case of a filament aggregate, the filaments may also be uncrimped fibers, but are preferably crimped fibers. The degree of crimping of the crimped fiber may be, for example, about 5 to 75, preferably about 10 to 50, and more preferably about 15 to 50 per 2.54 cm. In addition, crimped fibers that are uniformly crimped can be used.

(superabsorbent Polymer particles)

The absorbent body 56 may contain superabsorbent polymer particles in a portion or all of it. The superabsorbent polymer particles include "powders" in addition to "particles". As the superabsorbent polymer particles, the superabsorbent polymer particles used in such absorbent articles can be used directly. The particle diameter of the superabsorbent polymer particles is not particularly limited, and for example, the following particle diameters are preferable: screening was performed using a 500 μm standard sieve (JIS Z8801-1:2006) (shaking for 5 minutes), and screening was performed using a 180 μm standard sieve (JIS Z8801-1:2006) (shaking for 5 minutes) for particles falling under the sieve by the screening, at which time the proportion of particles remaining on the 500 μm standard sieve was 30% by weight or less and the proportion of particles remaining on the 180 μm standard sieve was 60% by weight or more.

The material of the superabsorbent polymer particles is not particularly limited, but a material having a water absorption capacity of 30g/g or more is preferable. As the super absorbent polymer particles, there are starch-based, cellulose-based, synthetic polymer-based, and the like, and starch-acrylic acid (salt) graft copolymer, saponified starch-acrylonitrile copolymer, crosslinked sodium carboxymethyl cellulose, acrylic acid (salt) polymer, and the like may be used. The shape of the super absorbent polymer particles is preferably a powder or granule of a commonly used super absorbent polymer, but other shapes of super absorbent polymer particles may be used.

As the superabsorbent polymer particles, those having a water absorption rate of 70 seconds or less, particularly 40 seconds or less are preferably used. When the water absorption rate is too low, so-called back flow is liable to occur, that is, the liquid supplied into the absorber 56 is returned to the outside of the absorber 56.

The super absorbent polymer particles preferably have a gel strength of 1000Pa or more. Thus, even when the bulk absorber 56 is produced, the sticky feeling after the liquid absorption can be effectively suppressed.

The basis weight of the superabsorbent polymer particles may be suitably determined in accordance with the amount of absorption required for the use of the absorbent body 56. Therefore, it cannot be said that the concentration of the catalyst is 50 to 350g/m ² . The basis weight of the polymer is less than 50g/m ² In this case, it is difficult to ensure the absorption amount. Exceeding 350g/m ² In this case, not only the effect is saturated, but also the particle-like uncomfortable feeling is caused by the excessive amount of the super absorbent polymer particles.

(packaging sheet)

The absorber 56 may be incorporated as the absorbent unit 50 wrapped with the wrapping sheet 58 in order to prevent the release of the superabsorbent polymer particles or to improve the shape retention of the absorber 56. As the wrapping sheet 58, a paper towel, particularly a crepe paper, a nonwoven fabric, a polyethylene laminated nonwoven fabric, a sheet with holes, or the like can be used. Among them, high absorption is preferableA tablet in which the sexual polymer particles do not come out. In the case of using nonwoven fabrics instead of crepe papers, hydrophilic SMMS (spunbond/meltblown/spunbond) nonwoven fabrics are particularly preferable, and polypropylene, polyethylene/polypropylene, and the like can be used as the material thereof. The fiber basis weight is preferably 5-40 g/m ² Particularly preferably 10 to 30g/m ² 。

The wrapping sheet 58 may be configured to wrap the entire absorber 56 with one sheet, or may be configured to wrap the entire absorber 56 with a plurality of sheets such as upper and lower 2 sheets, as shown in fig. 3. The wrapper 58 may also be omitted.

(Top sheet)

The top sheet 30 has liquid permeability, and for example, nonwoven fabric having holes or no holes, a porous plastic sheet, or the like can be used. The type of the raw material fibers of the nonwoven fabric is not particularly limited. Examples thereof include synthetic fibers such as olefin-based fibers, polyester-based fibers, and polyamide-based fibers, such as polyethylene and polypropylene; regenerated fibers such as rayon and cuprammonium fibers; natural fibers such as cotton, and mixed fibers and composite fibers using two or more of these. The nonwoven fabric may be produced by any processing. As the processing method, known methods, for example, a hydroentangling method, a spunbonding method, a thermal bonding method, a melt blowing method, a needle punching method, a hot air method, a spot bonding method, and the like can be exemplified. For example, if softness and drape are required, the hydroentangling method is a preferable processing method, and if fluffiness and softness are required, the thermal bonding method is a preferable processing method.

The top sheet 30 extends from the front end to the rear end of the product in the front-rear direction and extends to a position laterally of the absorber 56 in the width direction WD, but for example, when the starting point of the standing gathers 60 described later is located at a position closer to the widthwise center side than the side edges of the absorber 56, etc., appropriate deformation such as making the width of the top sheet 30 shorter than the full width of the absorber 56 may be performed as needed.

(middle piece)

In order to allow the liquid having penetrated the top sheet 30 to be rapidly transferred to the absorbent body, an intermediate sheet (also referred to as "second sheet") 40 having a liquid penetration rate faster than that of the top sheet 30 may be provided. The intermediate sheet 40 serves to rapidly transfer the liquid to the absorbent body, to improve the absorption performance of the absorbent body, and to prevent the phenomenon of "back flow" of the absorbed liquid from the absorbent body. The intermediate sheet 40 may also be omitted.

Examples of the intermediate sheet 40 include the same material as the top sheet 30, a spun-laced nonwoven fabric, a spun-bond nonwoven fabric, an SMS nonwoven fabric, a pulp nonwoven fabric, a mixed sheet of pulp and rayon, a point-bond nonwoven fabric, and a crepe paper. In particular, a hot air nonwoven fabric is preferable because of its bulkiness. In this case, the resin used for the core may be polypropylene (PP), but Polyester (PET) having high rigidity is preferable. The fiber basis weight is preferably 17-80 g/m ² More preferably 25 to 60g/m ² . The coarseness of the raw material fibers of the nonwoven fabric is preferably 2.0 to 10dtex. For fluffing the nonwoven fabric, it is preferable to use, as all or part of the mixed fibers of the raw material fibers, a core-spun fiber or a hollow fiber having a core not at the center, or a core-spun hollow fiber.

The intermediate sheet 40 in the example shown in the figure is shorter than the width of the absorber 56 and is disposed in the center, but the intermediate sheet 40 may be disposed over the entire width. The intermediate sheet 40 may be provided over the entire length of the diaper, but may be provided only in the middle portion including the excretion position as shown in the example.

(liquid-impermeable resin film)

The liquid-impermeable resin film 11 is not particularly limited as long as it has moisture permeability, and for example, a microporous sheet obtained by kneading an inorganic filler into an olefin resin such as polyethylene or polypropylene, molding the sheet, and stretching the sheet in a uniaxial or biaxial direction can be suitably used. Of course, the liquid-impermeable resin film 11 does not include a material having a nonwoven fabric as a base material to improve the water repellency.

The liquid-impermeable resin film 11 preferably extends in the front-rear direction LD and the width direction WD over the same or a wider range than the absorber 56, and may be set so as not to cover the ends of the absorber 56 in the front-rear direction LD and the width direction WD, if necessary, in the presence of other water blocking means or the like.

(exterior nonwoven fabrics)

The exterior nonwoven fabric 12 covers the entire back of the liquid-impermeable resin film 11The outer surface of the product is provided with a cloth-like appearance. The exterior nonwoven fabric 12 is not particularly limited, and for example, as a raw material fiber, a regenerated fiber such as rayon or cuprammonium fiber, a natural fiber such as cotton, or the like may be used in addition to a synthetic fiber such as an olefin fiber such as polyethylene or polypropylene, a polyester fiber, or a polyamide fiber, and as a processing method, a hydroentangling method, a spunbonding method, a thermal bonding method, a hot air method, a needle punching method, or the like may be used. Among them, spun-bonded nonwoven fabrics, SMS nonwoven fabrics, SMMS nonwoven fabrics and other fiber nonwoven fabrics are preferable from the viewpoint of achieving both the skin touch and strength. The nonwoven fabric may be used by overlapping a plurality of nonwoven fabrics, instead of one nonwoven fabric. In the latter case, the nonwoven fabrics are preferably bonded to each other by a hot melt adhesive or the like. In the case of using a nonwoven fabric, the fiber basis weight thereof is preferably 10 to 50g/m ² Particularly preferably 15 to 30g/m ² 。

The exterior nonwoven fabric 12 may be bonded to the liquid-impermeable resin film 11 or the moisture-absorbing sheet 15 described later by an adhesive such as a hot-melt adhesive applied in an appropriate pattern or by a member adjacent to the front side by welding of the raw materials, that is, in the case of the illustrated example.

(standing gathers)

In order to prevent excrement from moving laterally along the top sheet 30 and to prevent so-called side leakage, standing gathers 60 that stand up toward the skin side of the wearer are preferably provided on both sides of the surface in the width direction WD. Of course, the standing gathers 60 may also be omitted.

In the case of using the standing gathers 60, the structure thereof is not particularly limited, and any known structure may be used. The standing gathers 60 illustrated in the drawing are composed of a gather sheet 62 that is substantially continuous in the width direction WD, and an elongated gather elastic member 63 that is fixed to the gather sheet 62 in an elongated state along the front-rear direction LD. As the gather sheet 62, a water-repellent nonwoven fabric may be used, and as the gather elastic member 63, a rubber thread or the like may be used. In addition to the plurality of elastic members, as shown in fig. 1 and 2, 1 elastic member may be provided.

The inner surface of the gather sheet 62 has a joining start end in the width direction WD on the side portion of the top sheet 30, and a portion outside the joining start end in the width direction is joined to the inner surface of each side flap portion SF, that is, the side portion of the liquid-impermeable resin film 11 and the side portion of the exterior nonwoven fabric 12 outside the side portion in the width direction in the illustrated example, by a hot-melt adhesive or the like.

At the leg-surrounding portions, portions on the inner side in the width direction than the joining start ends of the standing gathers 60 are fixed to the top sheet 30 at both end portions in the product front-rear direction, but portions therebetween are free portions that are not fixed, and the free portions stand up by the contraction force of the elastic members 63, and are in close contact with the body surface.

(end wing, side wing)

The illustrated belt-type disposable diaper has a pair of end flaps EF extending toward the front and rear sides of the absorber 56, respectively, and does not have the absorber 56, and a pair of side flaps SF extending laterally from both side edges of the absorber 56, respectively, and does not have the absorber 56.

(planar pleats)

Side elastic members 64 made of an elongated elastic member such as a rubber string are fixed to each side flap portion SF in a state of being elongated in the front-rear direction LD, whereby leg-surrounding portions of each side flap portion SF are configured as planar gathers. The side elastic member 64 may be provided between the liquid-impermeable resin film 11 and the exterior nonwoven fabric 12 in the side flap portion SF, in addition to being provided between the gather sheet 62 and the liquid-impermeable resin film 11 on the outer side in the width direction near the joining start end in the joining portion of the gather sheet 62 as in the illustrated example. In addition to providing a plurality of side elastic members 64 on each side as in the illustrated example, only 1 side elastic member may be provided.

(connecting band)

The side wing portions SF in the back side portion B are respectively provided with a connecting band 13, and the connecting bands 13 are detachably connected to the outer surface of the abdominal side portion F. When the diaper is worn, the connecting band 13 is wound around the outer surface of the abdomen-side portion F from both sides of the waist, and the connecting portion 13A of the connecting band 13 is connected to an appropriate position on the outer surface of the abdomen-side portion F.

The structure of the connecting band 13 is not particularly limited, and in the illustrated example, it includes: a sheet base material that forms a tape mounting portion 13C fixed to the side wing portion SF and a tape main body portion 13B protruding from the tape mounting portion 13C; and a connecting portion 13A provided in a widthwise intermediate portion of the band main body portion 13B of the sheet base material and connected to the abdominal side, the portion on the front end side of the connecting portion 13A serving as a grip portion.

As the connecting portion 13A, an adhesive layer may be provided in addition to a hook (male) member of a mechanical fastener (face fastener). The hook member has a plurality of engaging protrusions on its connection surface, and the engaging protrusions may have any shape, such as (a) a shape of a pair of legs, (B) a shape of a pair of legs, (C) a mushroom, (D) a shape of a pair of legs (E) a shape of a pair of legs (a shape in which the engaging protrusions of the pair of legs are joined back to back).

Further, as the sheet base material formed from the tape mounting portion 13C to the tape main body portion 13B, nonwoven fabric, plastic film, polyethylene laminated nonwoven fabric, paper or a composite material thereof can be used, preferably having a fineness of 1.0 to 3.5dtex and a basis weight of 20 to 100g/m ² A spun-bonded nonwoven fabric, a hot air nonwoven fabric, or a spun-laced nonwoven fabric having a thickness of 1mm or less.

(target piece)

The target piece 20 having a target for facilitating the connection is preferably provided at the connection portion of the connection belt 13 in the abdominal portion F. In the case where the connection portion 13A is a hook, the target sheet 20 may be one in which a large number of loop yarns around which engaging protrusions of the hook are wound are provided on the surface of a sheet base made of a plastic film or a nonwoven fabric, or in the case of an adhesive layer, a target sheet in which a release treatment is performed on the surface of a sheet base made of a plastic film having a smooth surface with high adhesion may be used. In the case where the joining portion of the joining belt 13 in the abdominal portion F is formed of a nonwoven fabric, for example, in the case where the exterior nonwoven fabric 12 is provided as in the illustrated example, the target sheet 20 may be omitted, and the hook material may be wound around the fibers of the exterior nonwoven fabric 12 and joined. In this case, a target sheet 20 as a mark may be provided between the exterior nonwoven fabric 12 and the liquid impermeable resin film 11.

(absorbent sheet)

As shown in fig. 8 to 10, a moisture absorbing sheet 15 is provided between the liquid impermeable resin film 11 and the exterior nonwoven fabric 12. If such a moisture-absorbing sheet 15 is provided between the liquid-impermeable resin film 11 and the exterior nonwoven fabric 12, the moisture that has penetrated through the liquid-impermeable resin film 11 is not blocked by the moisture-absorbing sheet 15, and therefore the heat resistance during wearing is not easily reduced. Even so, due to the high hygroscopicity of the microfibrous cellulose aggregates, moisture is held in the moisture-absorbent sheet 15 as compared with the outer nonwoven fabric 12 or undergarment constituting the outer surface of the product, and thus the outer surface of the product or the undergarment is less likely to develop a moist touch.

In particular, as shown in fig. 11, the absorbent sheet 15 preferably has: a nonwoven fabric 16 in which thin portions 16t that shrink in the thickness direction are repeatedly formed at intervals; and microfibrous cellulose aggregates 17 attached in the thin-walled portion 16t. The thin portion 16t may have a recess on only one of the front and back sides of the absorbent sheet 15, in addition to having recesses on both the front and back sides of the absorbent sheet 15 as in the illustrated example. Thus, the absorbent sheet 15 is sandwiched between the liquid-impermeable resin film 11 and the exterior nonwoven fabric 12, but a ventilation gap 18 is formed between the sheet and the thin portion 16t of the absorbent sheet 15. Therefore, in the present absorbent sheet 15, moisture can be released along the surface of the absorbent sheet 15 through the ventilation gap 18. In addition, in this process, moisture can be efficiently supplied to the microfibrous cellulose aggregates 17 as a moisture absorbing material to absorb moisture.

The absorbent sheet 15 may have microfibrous cellulose aggregates 17 in addition to the thin wall portions 16t, but the microfibrous cellulose aggregates 17 are hard. Therefore, the absorbent sheet 15 preferably has the microfibrous cellulose aggregates 17 attached only to the thin wall portion 16t. As a result, the portions of the absorbent sheet 15 other than the thin portion 16t can be deformed flexibly, and the user or the wearer does not easily touch the hard thin portion 16t or the hardness thereof is not easily transmitted to the skin.

The thin portions 16t may be formed in a repeating pattern with a space therebetween, and the pattern is not particularly limited. For example, the thin-walled portion 16t may be a longitudinal stripe shape in which a plurality of thin-walled portions 16t in a linear shape along the front-rear direction LD are arranged at intervals in the width direction WD as shown in fig. 8, or may be a transverse stripe shape in which a plurality of thin-walled portions 16t in a linear shape along the width direction WD are arranged at intervals in the front-rear direction LD as shown in fig. 9. The thin portion 16t may be dot-shaped as shown in fig. 12 (a) to (e), or may be inclined-lattice-shaped as shown in fig. 12 (f). In particular, if the thin portions 16t are provided in a stripe or lattice shape, the continuity of the ventilation gap 18 is improved. Therefore, the air permeability for releasing moisture, and the air permeability for effectively supplying moisture to the moisture absorbent material are more excellent, and thus are preferable. In the case where the thin portion 16t is made to be continuous in a linear shape as described above, it may be continuous in a curved shape or a wavy line shape in addition to being continuous in a linear shape.

The size of the thin-walled portion 16t can be appropriately determined. When the thin portions 16t are arranged in a stripe pattern, the line width x1 of the thin portions 16t is preferably 1.0 to 4.0mm, particularly preferably 2.0 to 3.0mm, and the interval s1 between adjacent adhesion portions is preferably 5 to 30mm, particularly preferably 10 to 20mm. In the case where the thin portion 16t is a dot pattern, the diameter d (length of the longest portion) of the thin portion 16t is preferably 1.0 to 4.0mm, particularly preferably 2.0 to 3.0mm, and the center (or center of gravity) intervals s2, s3 between adjacent rows in the width direction WD and the front-rear direction LD are preferably 5 to 25mm, particularly preferably 10 to 15mm. In the case where the thin portions 16t are arranged in a lattice pattern, the line width x2 of the thin portions 16t is preferably 1.0 to 4.0mm, particularly preferably 2.0 to 3.0mm, and the lattice spacing s4 (the spacing between the parallel thin portions 16 t) is preferably 5 to 30mm, particularly preferably 10 to 20mm. The size of the attached portion of the microfibrous cellulose aggregate may be the same as the size of the thin-walled portion 16t, or smaller or larger than the size of the thin-walled portion 16t.

The nonwoven fabric 16 constituting the absorbent sheet 15 is not particularly limited, but is preferably fluffy and excellent in shape-forming properties, and therefore, preferably has a fineness of 2 to 10dtex and a basis weight of 20 to 40g/m ² Is a staple fiber nonwoven fabric.

In order to improve hygroscopicity, the more the amount of microfibrous cellulose is, the better, but if it is too much, the product becomes unnecessarily stiff. Accordingly, the content of microfibrous cellulose in the thin portion 16t is preferably 0.1 to 5.0g/m ² About, and particularly preferably 0.5 to 3.0g/m ² Left and right.

< manufacturing method >

For example, the absorbent sheet 15 can be produced by forming the thin-walled portion 16t on the nonwoven fabric 16 that becomes the absorbent sheet 15 by embossing and simultaneously or thereafter adhering the microfibrous cellulose aggregates 17 to the thin-walled portion 16t.

The absorbent sheet 15 can be manufactured by the following method. That is, when the dispersion liquid of the microfibrous cellulose is applied to the nonwoven fabric 16 serving as the absorbent sheet 15 in a repeating pattern at intervals, the dispersion liquid penetrates between the fibers of the nonwoven fabric 16. Then, when it is dried, a thin wall portion 16t is formed in the coating portion of the dispersion liquid, and at the same time, a microfibrous cellulose aggregate 17 is formed in the thin wall portion 16t. That is, when the dispersion liquid of the microfibrous cellulose is applied to the nonwoven fabric 16 and then the dispersion liquid of the applied portion is dried, the volume of the microfibrous cellulose aggregates 17 gradually decreases when the microfibrous cellulose aggregates 17 are formed. With this, the volume of the applied portion of the dispersion liquid of the nonwoven fabric 16 is also reduced, and the thin portion 16t is automatically formed. The present manufacturing method takes advantage of this. According to this method, the absorbent sheet 15 can be formed by simply applying a dispersion of microfibrous cellulose onto the nonwoven fabric 16 serving as the absorbent sheet 15 in a desired pattern and drying the same.

However, according to this production method, if other sheets are attached after the dispersion liquid of microfibrous cellulose is applied to the nonwoven fabric 16 and before drying (i.e., before forming the thin wall portion 16 t), the air-permeable gap 18 may not be formed. Therefore, in the case of attaching the present absorbent sheet 15 to another member, it is preferable to attach the other member after forming the thin portion 16t. For example, the thin portion 16t can be formed in principle by applying a dispersion of microfibrous cellulose to a conventional nonwoven fabric 16 member such as the intermediate sheet 40 or the exterior nonwoven fabric 12. However, since it is necessary to attach other members after drying the dispersion of microfibrous cellulose, the method is not suitable for manufacturing using a high-speed production line. Therefore, as shown in the example, it is preferable to manufacture a disposable wearing article by separately manufacturing a dedicated absorbent sheet 15 and attaching it between appropriate members. In contrast, in the case where the thin portion 16t is formed by embossing, other members may be bonded to the nonwoven fabric 16 serving as the absorbent sheet 15 before the dispersion of microfibrous cellulose is applied.

In the case where the attached portion of the microfibrous cellulose aggregates 17 is formed by application of the microfibrous cellulose dispersion, the concentration (mass/volume) of the microfibrous cellulose dispersion is preferably 0.1 to 10%, more preferably 1.0 to 5.0%, particularly preferably 1.5 to 3.0%.

The type B viscosity (60 rpm, 20 ℃) of the microfibrous cellulose dispersion is, for example, 700cps or less, preferably 200cps or less, more preferably 50cps or less. By suppressing the B-type viscosity of the microfibrous cellulose dispersion liquid in this way low, microfibrous cellulose is uniformly imparted to the nonwoven fabric.

As for the application of the microfibrous cellulose dispersion, a transfer method such as a relief method may be used in addition to spraying onto the target surface.

Examples of pulp fibers that can be used for the production of microfibrous cellulose include chemical pulp such as hardwood pulp (LBKP) and softwood pulp (NBKP), mechanical pulp such as bleached thermomechanical pulp (BTMP), terrazzo pulp (SGP), pressure terrazzo Pulp (PGW), refined terrazzo pulp (RGP), chemical terrazzo pulp (CGP), high Wen Modan terrazzo pulp (TGP), terrazzo pulp (GP), thermomechanical pulp (TMP), chemical thermomechanical pulp (CTMP), and disc-milling mechanical pulp (RMP); waste paper pulp produced from tea waste paper, kraft envelope waste paper, magazine waste paper, newspaper waste paper, leaflet waste paper, office waste paper, corrugated paper waste paper, high white waste paper, kente waste paper, imitation waste paper, security waste paper, grass paper waste paper, and the like; deinked pulp (DIP) obtained by deinking waste paper pulp, and the like. These pulps may be used alone or in combination of two or more kinds thereof as long as the objective effect is not impaired. Further, a material obtained by subjecting the pulp fiber to chemical treatment such as carboxymethylation may be used.

Examples of the method for producing microfibrous cellulose include mechanical methods such as a high-pressure homogenizer method, a high-pressure microfluidizer method, a grinding mill method, a bead mill freeze-grinding method, and an ultrasonic defibration method, but are not limited to these methods. Microfibrillation is promoted by a combination of TEMPO oxidation treatment, phosphorylation treatment, acid treatment, and the like.

< others >

The absorbent sheet 15 may be used alone or may be attached to other parts of the disposable wearing article. In use, the non-breathable member or the hardly breathable member may be adjacent to either one or both of the front and back sides of the absorbent sheet 15, the breathable material may be adjacent to both of the front and back sides, or the member adjacent to either one of the front and back sides may not be provided.

For example, as shown in fig. 9, the absorbent sheet 15 may be provided between members such as the waist, or as shown in fig. 10, the absorbent sheet 15 may be provided on the back side of the target sheet 20 (for example, between the target sheet 20 and the outer nonwoven fabric 12 or between the outer nonwoven fabric 12 and the liquid impermeable resin film 11).

In particular, when the absorbent sheet 15 is provided so as to have a portion adjacent to the back side of the skin contact layer having air permeability that contacts the skin of the wearer (the entire portion may be adjacent to the back side of the skin contact layer) in order to prevent the wearer from being stuffy during wearing, moisture in the inside of the disposable wearing article can be effectively absorbed or released to the outside, and thus the stuffy can be prevented. For example, in the example shown in fig. 9, in the case where the absorbent sheet 15 is provided at the waist portion, the absorbent sheet 15 may be provided between the topsheet 30 and the liquid impermeable resin film 11 from between the absorber 56 and the liquid impermeable resin film 11.

< description of the words in the specification >

Unless otherwise specified in the specification, the following terms in the specification have the following meanings.

"front-rear direction" refers to a direction (longitudinal direction) indicated by a reference numeral LD in the drawing, and "width direction" refers to a direction (left-right direction) indicated by WD in the drawing, the front-rear direction being orthogonal to the width direction.

"MD direction" and "CD direction" refer to a flow direction (MD direction) in a manufacturing apparatus and a cross direction (CD direction) orthogonal to the flow direction, and either one becomes the front-back direction and the other becomes the width direction depending on the portion of the product. The MD direction of the nonwoven fabric is the direction in which the fibers of the nonwoven fabric are oriented. The fiber orientation refers to the direction along which the fibers of the nonwoven fabric are oriented, and can be determined by, for example, a measurement method according to a fiber orientation test method based on zero-distance tensile strength of TAPPI standard method T481, or a simple measurement method for determining the fiber orientation direction from the tensile strength ratio in the front-rear direction to the width direction.

"front side" refers to the side that is closest to the wearer's skin when worn and "back side" refers to the side that is furthest from the wearer's skin when worn.

"surface" refers to the face of the component that is closest to the wearer's skin when worn, and "back" refers to the face of the component that is furthest from the wearer's skin when worn.

"elongation" refers to a value given a natural length of 100%. For example, an elongation of 200% is the same as an elongation of 2 times.

"gel Strength" is determined as follows. To 49.0g of artificial urine (prepared by mixing urea: 2wt%, sodium chloride: 0.8wt%, calcium chloride dihydrate: 0.03wt%, magnesium sulfate heptahydrate: 0.08wt% and ion-exchanged water: 97.09 wt%), 1.0g of a super absorbent polymer was added and stirred by a stirrer. The gel thus produced was allowed to stand in a constant temperature and humidity tank at 40℃X 60% RH for 3 hours, then returned to normal temperature, and the gel strength was measured by a curd meter (manufactured by I.techno Engineering Co., ltd.: curdetter-MAX ME-500).

"basis weight" is determined as follows. After the sample or test piece was predried, it was placed in a laboratory or apparatus in a standard state (the temperature at the test site was 23.+ -. 1 ℃ C. And the relative humidity was 50.+ -. 2%) to be in a state of reaching a constant amount. Predrying means that the sample or test piece is brought to a constant amount in an environment at a temperature of 100 ℃. The fibers having a predetermined moisture regain of 0.0% may not be pre-dried. Using a template (template) for sample collection (100 mm. Times.100 mm), a sample of 100 mm. Times.100 mm in size was cut from a test piece in a constant state. The weight of the sample was measured, multiplied by 100, and the weight per 1 square meter was calculated as the basis weight.

"thickness" using an automatic thickness gauge (KES-G5 portable compression tester), under load: 0.098N/cm ² Area under pressure: 2cm ² Is automatically determined under the condition of (2). The thickness of the perforated nonwoven fabric was measured at a portion other than the holes and the projections around the holes.

The water absorption was measured by the method of JIS K7223-1996 "test method for water absorption of superabsorbent resin".

The water absorption rate was measured using "time to endpoint" in JIS K7224-1996 "test method for water absorption rate of superabsorbent resin" using 2g of superabsorbent polymer and 50g of physiological saline.

The term "microfibrous cellulose" refers to a fine cellulose fiber or a bundle thereof extracted from a plant such as pulp, and generally refers to a fibrous cellulose having an average fiber width of from 1 to 1000nm, preferably a cellulose having an average fiber width (median diameter) of 100nm or less (generally referred to as Cellulose Nanofibrils (CNF)), and particularly preferably a cellulose having an average fiber width of from 10 to 60 nm.

The "average fiber width" of microfibrous cellulose can be measured by the following method. Specifically, first, 100ml of an aqueous dispersion of microfibrous cellulose having a solid content of 0.01 to 0.1 mass% was filtered using a teflon (registered trademark) membrane filter, and 1 solvent substitution was performed using 100ml of ethanol, and 3 solvent substitutions were performed using 20ml of t-butanol. Subsequently, the resulting mixture was freeze-dried and coated with osmium to prepare a sample. For this sample, observation based on an electron microscope SEM image was performed at any magnification (magnification of 30000 in this example) of 5000 times, 10000 times, or 30000 times depending on the width of the fibers constituted. Specifically, two diagonal lines are drawn in the observation image, and three straight lines passing through the intersection points of the diagonal lines are arbitrarily drawn. Further, a total of 100 fiber rods interlaced with the three straight lines were visually measured. The median diameter (median diameter) of the measured values was taken as the average fiber width.

"expanded state" refers to a state in which the device expands flat without contraction or relaxation.

Unless otherwise specified, the dimensions of the respective portions refer to the dimensions in the expanded state rather than the natural length state.

The test or measurement is carried out in a laboratory or apparatus in a standard state (a temperature at a test site of 23.+ -. 1 ℃ C. And a relative humidity of 50.+ -. 2%) without any description of environmental conditions in the test or measurement.

Industrial applicability

The present invention can be applied to all disposable diapers such as pants-type disposable diapers and pad-type disposable diapers, in addition to the belt-type disposable diapers as exemplified above, and can be applied to other absorbent articles such as sanitary napkins.

Description of the reference numerals

11 … liquid-impermeable resin film, 12 … outer nonwoven fabric, 13 … connecting belt, 13a … connecting portion, 13B … belt main body portion, 13C … belt mounting portion, 15 … absorbent sheet, 16 … nonwoven fabric, 16t … thin wall portion, 17 … microfibrous cellulose aggregate, 18 … gap, 20 … target sheet, 30 … top sheet, 40 … middle sheet, 50 … absorbent unit, 56 … absorbent body, 58 … packaging sheet, 60 … standing gather, 62 … gather sheet, B … back side portion, F … ventral side portion, WD … width direction, LD … front-rear direction.

Claims

1. An absorbent sheet comprising:

a dry microfibrous cellulose aggregate adhering to the fibers in the thin wall portion,

the depressions of the thin wall parts are arranged on the two sides of the front side and the back side of the moisture absorption sheet,

the nonwoven fabric constituting the absorbent sheet has a fineness of 2dtex to 10dtex and a basis weight of 20g/m ² ～40g/m ² Is a non-woven fabric of short fibers of (3),

the amount of the microfibrous cellulose aggregates in the thin-walled portion was 0.5g/m ² ～3.0g/m ² 。

2. The absorbent sheet according to claim 1, wherein the microfibrous cellulose aggregates are absent except for the thin-walled portion.

3. The absorbent sheet according to claim 1 or 2, wherein the thin wall portions are provided in a stripe or lattice shape.

4. A disposable wearing article comprising:

an absorber;

the disposable wearing article is characterized in that,

has a moisture-absorbing sheet disposed between the liquid-impermeable resin film and the exterior nonwoven fabric,

the absorbent sheet has: a nonwoven fabric in which thin wall portions that shrink in the thickness direction are repeatedly formed at intervals; and a dried microfibrous cellulose aggregate attached to the fibers in the thin wall portion,

ventilation gaps are respectively formed between the outer non-woven fabric and the concave of the thin wall part and between the liquid impermeable resin film and the concave of the thin wall part,

5. A disposable wearing article comprising:

a ventilation gap is formed between the skin contact layer and the concave of the thin wall part,

6. A method for manufacturing a disposable wearing article, comprising the steps of:

a step of applying a dispersion of microfibrous cellulose to a nonwoven fabric at intervals in a repeating pattern, and drying the dispersion penetrating into the nonwoven fabric between fibers, thereby producing a moisture-absorbing sheet having thin wall portions formed in the applied portion of the dispersion and having dry microfibrous cellulose aggregates attached to the fibers in the thin wall portions, wherein the moisture-absorbing sheet has depressions in the thin wall portions on both front and back sides thereof; and

a step of attaching the absorbent sheet having the recesses of the thin wall portions on both front and back sides thereof between members overlapping in a thickness direction of the disposable wearing article to manufacture the disposable wearing article having an air-permeable gap between the members and the thin wall portions,