RU159420U1 - ABSORBENT PRODUCT - Google Patents

Abstract

1. An absorbent article comprising a liquid-permeable topsheet on the skin side of the surface, a liquid-impermeable topsheet on the non-skinned side of the surface, and an absorbent member located between these sheets and including an intermediate layer located between the topsheet and the absorbent member moreover, the top sheet includes numerous bulges protruding towards the skin of the user, and numerous recesses adjacent to the bulges, the intermediate layer contains A crosslinked cellulose fiber, the absorbent element includes an absorbent core containing absorbent material, and a core wrapping sheet covering at least the skin-facing surface of the absorbent core, and containing paper or a hydrophilic non-woven fabric, and the liquid penetration time into the first, second and the third time is 60 seconds or less when re-measuring the liquid penetration time three or more times by the measurement method with respect to the core wrapping sheet. 2. The absorbent article of claim 1, wherein the core-wrapping sheet includes a nonwoven fabric obtained by a spinneret - aerodynamic - spinneret method, and a spunbond nonwoven web forming at least one surface of the nonwoven web contains a synthetic fiber mixed with a hydrophilizing substance using synthetic a polymer in which the hydrophilizing agent is premixed as a fibrous starting material. 3. The absorbent article of claim 1, wherein the core wrapping sheet has a width of at least h

Description

Technical field

The present utility model offers an absorbent article such as a disposable diaper or sanitary pad.

State of the art

As a type of absorbent article, an article is known comprising a liquid-permeable top sheet, a liquid-impervious lower sheet and an absorbent element located between the sheets, and also comprising an intermediate layer that contains a hydrophilic fiber and is located between the upper sheet and the absorbent element. In addition, an absorbent element is known as an absorbent element, including an absorbent core that contains an absorbent material, such as wood pulp or an absorbent polymer, and a core-wrapping sheet that covers the absorbent core. The core-wrapping sheet functions as a sheet that contains absorbent material when the absorbent element is manufactured, and which wraps and shapes the absorbent core after the manufacture of the absorbent element. As a core-wrapping sheet, a permeable sheet such as tissue paper, absorbent paper or non-woven fabric is known.

For example, Patent Document 1 describes an absorbent article in which a liquid-retaining system containing chemically cross-linked cellulose fiber is located between the top sheet and an absorbent core in which cellulose is substantially absent. It has been found that the absorbent article described in Patent Document 1 has improved liquid absorption properties and provides higher dry characteristics compared to a conventional article.

In addition, Patent Document 2 describes an absorbent article comprising an absorbent element that contains an absorbent polymer and a cellulosic fiber, and in which a crosslinked cellulosic fiber made by crosslinking within the cellulose molecules or between the cellulose molecules using a crosslinking agent is used as the cellulosic fiber. In addition, Patent Document 2 describes that an absorbent element contains diffusion absorbent paper, which has a surface density of 20 to 60 g / m ² , and a penetration time of an aqueous solution containing 85% by weight of glycerol through diffusion absorbent paper is 100 seconds or less. It has been found that the absorbent article described in Patent Document 2 is excellent in absorption rate, in particular in re-absorption rate, has high immobilization ability of biological fluid and has excellent liquid return property and liquid leakage prevention property.

In addition, Patent Document 3 describes an absorbent core comprising an absorbent layer and a stable hydrophilic fluid-permeable substrate wrapping the core, wherein this core wrapping substrate made by applying a hydrophilic coating to the non-woven fabric has storage stability, does not erode during leakage and can provide a high absorption rate of the liquid when the liquid repeatedly affects the non-woven fabric, and increases the hydrophilicity of ytiya composition comprises nanoparticles, wherein the diameter increasing hydrophilicity of the particles is from about 1 to 750 nm. In addition, in Patent Document 3, the expression “increasing hydrophilicity” means that the absorption time with respect to the initial leakage of liquid allows 5 ml of liquid to flow through a sample measuring 12.5 × 12.5 cm, and the fifth absorption time is approximately 6 seconds or less, when the composition is applied to the core wrapping substrate in the manufacture of a stable hydrophilic fluid-permeable core wrapping substrate.

List of references

Patent Literature

Patent Document 1: US Patent Application No. 20088312621 (A1)

Patent Document 2: Japanese Patent Application No. 07-255776 A

Patent Document 3: US Patent Application No. 2006253092 (A1)

Utility Model Essence

Technical problem

A crosslinked cellulosic fiber is hydrophobic compared to a conventional cellulosic fiber when a crosslinked cellulosic fiber is used as a hydrophilic fiber corresponding to the component of the intermediate layer, as described in Patent Document 2, in an absorbent article containing the intermediate layer described above. Thus, its effectiveness is that the liquid penetration rate increases from the bottom side of the sheet toward the bottom side of the sheet, and residual liquid is rarely formed. However, when the core-wrapping sheet that covers the absorbent core is between the intermediate layer and the absorbent core, in particular when the core-wrapping sheet becomes hydrophilic by applying a hydrophilizing substance to the surface of the fiber constituting the non-woven fabric, which is initially a water-repellent, hydrophilizing substance contained in core-wrap sheet flows with biological fluid due to repeated release the absorption and absorption of a biological fluid, such as urine, during use of an absorbent article. As a result of this, the problem arises that the hydrophilicity (hydrophobicity) of the core-wrapping sheet decreases, and thus the permeability with respect to the liquid decreases. When the biological fluid hardly penetrates the core wrapping sheet, the rate of penetration and absorption of the biological fluid decreases, and the biological fluid exiting onto the top sheet is easily retained in the intermediate layer located on the non-skin side of the surface of the upper sheet or between the intermediate layer and an absorbent element. Thus, the problem arises that residual liquid is easily formed, and the return of liquid in the direction of the top sheet is increased.

When coating a nanoparticle-containing composition that increases hydrophilicity, as described in Patent Document 3, in many studies, the absorption time of a small amount of liquid is retained, and the stability of hydrophilic properties is increased. However, a method for estimating absorption time is a method in which 5 ml of fluid flows through a sample measuring 12.5 x 12.5 cm, as described above, and the amount of fluid is significantly less than the urination rate for which the diaper is intended. Since the amount of liquid is small, leaching of nanoparticles rarely occurs. Thus, according to the utility model described in Patent Document 3, the nanoparticles are easily washed out in the event of repeated exposure to a large amount of liquid corresponding to the actual urination level for which the diaper is intended to be used, and thus, the problem arises that the hydrophilicity will be short . In addition, the problem arises that the nanoparticles will be removed under the influence of stress during the manufacture of the diaper. On the other hand, a coating device is required that inhibits the release of nanoparticles. However, such a device is not described in patent document 3. In particular, the introduction of such a device in the manufacturing process, as a rule, causes the problem of increasing the cost of production. Thus, no absorbent article has been proposed that has high permeability to liquids, maintains this high permeability to liquids for an extended period of time, reduces the residual liquid content in the intermediate layer, rarely causes liquid return and can be stably produced at low cost in a relatively simple way.

Solution

The present utility model provides an absorbent article comprising a liquid-permeable topsheet on the skin side of the surface, a liquid-impervious bottom sheet on the skin-non-skin side, and an absorbent member located between these sheets, and also including an intermediate layer located between the topsheet and an absorbent element, in which the intermediate layer contains a crosslinked cellulosic fiber, the absorbent element includes an absorbent core containing ab sorbent material and a core wrapping sheet covering at least the skin-facing surface of the absorbent core and containing paper or a hydrophilic non-woven fabric, and the liquid penetration time for the first, second and third times is 60 seconds or less when the penetration time is measured again liquid three or more times by the measurement method described below with respect to the core wrapping sheet.

Method for measuring liquid penetration time

Two cylinders having open upper and lower ends and an inner diameter of 35 mm are installed vertically, combining the axes of both cylinders, and a circle of filter paper having a diameter of 55 mm and covering the upper surface of the measured sheet (wrapping the core of the sheet), which has all sides 70 mm, inserted between the upper and lower cylinders. In this position, 40 g of artificial urine is introduced into the upper cylinder. Introduced artificial urine sequentially penetrates through the filter paper and the measured sheet and flows down from the lower end of the lower cylinder, passing through the lower cylinder. A time-dependent change in the mass of artificial urine flowing down from the lower cylinder is observed, a period of time is measured from the moment the introduction of artificial urine begins until the mass reaches 20 g, and this time is determined as the time of liquid penetration.

Useful effects of a utility model

According to the present utility model, an absorbent article is provided that has excellent permeability to liquids, has a small amount of residual liquid, rarely allows liquid to be returned, and can be stably produced at low cost in a relatively simple way.

Brief Description of the Drawings

FIG. 1 is a diagram illustrating a disposable diaper as an absorbent article according to an embodiment of the present utility model, showing a top view of the skin side of the surface (top sheet side), schematically illustrating a state in which the diaper is deployed on a plane by stretching the elastic member of each part.

FIG. 2 is a cross-sectional view schematically illustrating a cross-section along line I-I of FIG. 1 (section in the width direction).

FIG. 3 is an explanatory diagram of a method for measuring liquid penetration time.

FIG. 4 is a perspective view schematically illustrating with enlargement a portion of a top sheet according to another embodiment of the present utility model.

FIG. 5 is a cross-sectional view schematically illustrating a portion of the cross-section in the width direction of an absorbent article according to the present utility model comprising a top sheet illustrated in FIG. four.

FIG. 6 (a) is a perspective view illustrating an absorbent core according to another embodiment of the present utility model, and FIG. 6 (b) is a cross-sectional view schematically illustrating a state in which the cross-sectional surface is inverted along line II-II of FIG. 6 (a) (section in the width direction).

Description of Embodiments

The present utility model offers an absorbent article that has excellent permeability to liquids, has a small amount of residual liquid, rarely allows liquid to be returned, and can be stably produced at low cost in a relatively simple way.

Next, an absorbent article according to the present utility model is described with reference to the drawings illustrating a disposable diaper according to a preferred embodiment. The diaper 1 according to the embodiment is a so-called experimental disposable diaper. As illustrated in FIG. 1 and 2, the diaper 1 constitutes a liquid-permeable top sheet 2, liquid-impermeable or water-repellent (hereinafter referred to as the single term “liquid-impermeable”) lower sheet 3 and an absorbent element 4 located between these sheets 2 and 3, and there is also an intermediate a layer 5 located between the top sheet 2 and the absorbent element 4.

To describe the diaper 1 in more detail, the diaper 1 includes a liquid-permeable topsheet 2, forming a skin-facing surface, a liquid-impervious bottom sheet 3, a non-skin-facing surface, and an absorbent element 4 located between these sheets 2 and 3, and the diaper has a generally oblong shape in the longitudinal direction. All elements, including the upper sheet 2, the lower sheet 3 and the absorbent element 4, have an elongated shape in the longitudinal direction (in the X direction). Each element, including the upper sheet 2 and the lower sheet 3, is larger than the size of the absorbent element 4 and extends outside the absorbent element 4. As illustrated in FIG. 2, the size in the width direction Y of the top sheet 2 is less than the size in the width direction Y of the bottom sheet 3.

As illustrated in FIG. 1, the diaper 1 comprises a back portion A located on the rear side of the user when the user wears the diaper, a front portion B located on the front side of the user when the user wears the diaper, and a crotch portion C located on the crotch of the user when the user wears the diaper, in the longitudinal direction X. The crotch portion C includes a target area located opposite the user's excretory region when the user wears a diaper, and it occupies a middle position in the longitudinal the diagonal direction X of the diaper 1. The rear part A, the front part B and the crotch part X belong to the respective areas of the user, and the diaper covers these three areas, so that the total length in the longitudinal direction X of the diaper 1 is divided into three approximately equal parts.

In the present description, the longitudinal direction (X direction in the drawing) means the direction along the maximum side that the absorbent article (diaper 1) or its component (top sheet 2, absorbent core 40, etc.) has and the width direction (Y direction to drawing) means a direction perpendicular to the longitudinal direction. In addition, a skin-facing surface means a surface of an absorbent article or its component facing a user's skin when the user is wearing an absorbent article, and a non-skin surface means a surface of an absorbent article or its component that faces the opposite side of the skin (wearing side) when the user wears an absorbent article.

As illustrated in FIG. 1 and 2, a side sheet 7 including a side edge to which the elastic member 71 is attached is in a stretched state in each of both side parts in a longitudinal direction X of the diaper 1, and a pair of three-dimensional assemblies are formed in the crotch part C when the user wears the diaper . In addition, the elastic member 72 is located in the longitudinal direction X in the parts for the right and left legs that surround the legs of the user, and a pair of leg assemblies is formed when the elastic member 72 is cut in the parts for the legs when the user wears the diaper. A pair of side sheets 7 and 7, an upper sheet 2, an absorbent element 4, elastic elements 71 and 72, and a lower sheet 3 are suitably bonded to each other using known bonding means, such as hot-melt adhesive.

As illustrated in FIG. 1, both side edge parts in the longitudinal direction X of the rear part A of the diaper 1 include a pair of stretch strips 8 and 8, and both side edge parts in the longitudinal direction X of the front part B of the diaper 1 have a pair of rigid strips 9 and 9. Each strip, including a stretch strip 8 and a rigid strip 9, includes an inner lateral edge part in the longitudinal direction X, which is attached to the surface of the bottom sheet 3 not facing the skin or is attached between the side sheet 7 and the bottom sheet 3. Fastening is carried out tnym means, such as adhesive or heat sealing. The fixing tape 81, to which the target area is attached (not illustrated in the drawing), is formed from the protruding element of the mechanical surface fixer, is attached to each of the pair of stretch strips 8 and 8. In addition, the fixing region 82, which forms the surrounding element of the mechanical surface fixer, is present on the non-skin surface of the front part B of the diaper 1. A fixation area 82 is formed by attaching and fixing the female element of the mechanical surface Nogo unconverted retainer to the skin surface of the backsheet 3 by known joining means (such as for example adhesive, heat sealing, etc.), and it becomes possible releasable fixation target area of the fixing belt 81.

As illustrated in FIG. 1 and 2, the absorbent element 4 includes an absorbent core 40 containing absorbent material, and a core wrapping sheet 41 covering at least the skin-facing surface (skin-facing surface of the intermediate layer 5) of the absorbent core 40 and containing paper or a hydrophilic non-woven fabric . The core-wrapping sheet 41 and the absorbent core 40 may be connected to each other by known connecting means, such as hot-melt adhesive.

As illustrated in FIG. 1, the absorbent core 40 is in the form of a thin plate that is oblong in the longitudinal direction (X direction of the diaper 1) and includes a narrowed middle portion in the longitudinal direction X. The absorbent core 40 includes natural cellulose fiber, such as wood pulp, as absorbent material, a fibrous material, such as a hydrophilic synthetic fiber, and an absorbent polymer. A variety of polymers used in the art can be used as the absorbent polymer, and the absorbent polymer is typically present in particulate form. However, this form may be a fiber, etc.

The core-wrapping sheet 41 has a width of not less than two and not more than three times in the width direction Y of the absorbent core 40, and the entire surface area of each surface, including the surface of the absorbent core 40 facing the skin and the surface of the opposite side thereof not facing the skin, covers one detail of the core wrapping sheet 41. The absorbent element 4 is manufactured by placing the absorbent core 40 in the middle part in the width direction Y of one part of the core wrapping sheet 41, folding the side parts together in the width direction Y to the upper side of the surface of the absorbent core 40, connecting the two side edge parts to each other by known connecting means such as hot-melt adhesive and the like, forming a cylinder-shaped sheet 41, and turning the core wrapping sheet 41 on the reverse side.

The intermediate layer 5 is made of a material other than the absorbent element 4, and is a layer located between the upper sheet 2 and the absorbent element 4. the intermediate layer 5 is fully or partially glued to each element, including the upper sheet 2 and the absorbent element 4 (core wrapping sheet 41).

It is preferable that the intermediate layer 5 covers 20% or more, preferably 30% or more of the skin-facing surface (surface on the side of the top sheet 2) of the absorbent element 4. On the other hand, the upper limit of the degree of coating of the skin-facing surface of the absorbent element 4 is intermediate layer 5 is 80%, preferably 60%, and the range of coverage is preferably 20 to 80% and more preferably 30 to 60%. In addition, it turns out that the center layer is covered by the intermediate layer 5 (the intersection point of the bisector in the longitudinal direction X and the bisector in the width direction Y of the absorbent element 4) in the longitudinal direction X of the absorbent element 4, and it is more preferable that the center in the longitudinal direction X of the intermediate layer 5 is located near the front part B with respect to the bisector in the longitudinal direction X of the absorbent element 4. According to a variant implementation, the intermediate layer 5 is satisfactory t to these requirements.

The length (width) in the width direction Y of the intermediate layer 5 is less than that of the absorbent element 4 (see FIG. 2). It is preferable that the lateral edge in the longitudinal direction X of the intermediate layer 5 is located inside the lateral edge in the longitudinal direction X of the absorbent element 4 in the range from 5 mm or more to 20 mm or less. When the width of the intermediate layer 5 covers the entire width of the absorbent element 4, side leakage easily occurs. Therefore, this is not preferred. In addition, the length in the longitudinal direction X of the intermediate layer 5 is shorter than the absorbent element 4. It is preferable that the end edge in the width direction Y of the intermediate layer 5 is located inside the end edge in the width direction Y of the absorbent element 4 by 5 mm or more. When the length in the longitudinal direction X of the intermediate layer 5 covers the entire length of the absorbent element 4, leakage in the longitudinal direction X easily occurs. Thus, this is not preferred.

The intermediate layer 5 comprises a crosslinked cellulosic fiber, and is preferably a fiber-folded article that constitutes a fibrous material comprising a crosslinked cellulosic fiber. A crosslinked cellulosic fiber is a fibrous material made by crosslinking within molecules or between cellulose molecules using a crosslinking agent, and it is a hydrophilic fiber. However, a crosslinked cellulosic fiber has, for example, such characteristics that torsional or permanent deformation rarely occurs even when the fiber is wet, and a crosslinked cellulosic fiber rarely absorbs liquid prior to swelling due to crosslinking within or between the cellulose molecules. Even when the intermediate layer 5 is moistened with a biological fluid such as urine and is wet, the distance between the constituent fibers is stably maintained by using crosslinked cellulose fiber having characteristics such as the constituent fiber of the intermediate layer 5. Thus, it turns out that the absorption the space in which the liquid is temporarily contained in the intermediate layer 5 is constantly stabilized, the rate of liquid penetration from the the top sheet 2 to the side of the bottom sheet 3, and rarely is a residual liquid formed. Next, crosslinked cellulose fiber will be described.

With regard to crosslinked cellulose fiber, it is preferable that the crosslinking of the fiber is carried out both within the molecules and between the cellulose molecules. Examples of cellulosic fiber suitable as a crosslinked cellulosic fiber material include natural cellulosic fiber, such as wood pulp or cotton, regenerated cellulosic fiber, such as viscose, copper-ammonia fiber, tensel (silky fiber from eucalyptus cellulose), or lyocell (solution molding) cellulose in N-methyl-morpholine-N-oxide), and semisynthetic cellulose fiber, such as acetate fiber.

Examples of crosslinkers for cellulose fiber that are used in the manufacturing process of crosslinked cellulose fiber include an N-methylol-based compound such as dimethyl-ethylene urea or dimethyl-hydroxyethylene urea; polycarboxylic acid such as citric acid, tricarboxylic acid and butantetracarboxylic acid; and a polyglycidyl ether-based compound. You can use a crosslinking agent of the same type, and you can also use a combination of crosslinking agents of two or more types.

It turns out that the amount of crosslinking agent used is 0.2 mass. hours or more and 20 mass. hours or less per 100 mass. including cellulose fiber. When the amount used is less than 0.2 mass. h., the crosslink density is low, and thus, the elastic modulus is low when the crosslinked cellulosic fiber is in a wet state, and there is a problem that torsional / permanent deformation occurs. When the amount used exceeds 20 mass. h., the crosslinked cellulose fiber is excessively stiff, and there is a problem that the fiber will be brittle when subjected to stress. Exemplary methods for crosslinking cellulose fiber using a crosslinking agent include method (i) and method (ii), which will be described below. (i) A method in which the cellulosic fiber is impregnated with an aqueous solution of a crosslinking agent, to which a catalyst is added as necessary, dehydration of the cellulose fiber in such a way that the aqueous solution of the crosslinking agent meets the intended purpose, and then heating the cellulosic fiber to a crosslinking temperature; (ii) a method of applying an aqueous solution of a crosslinking agent to a cellulosic fiber by spraying and the like, such that an aqueous solution of a crosslinking agent fulfills a predetermined purpose, and then heating the cellulosic fiber to a crosslinking temperature fulfills a predetermined purpose, and then heating the cellulosic fiber to crosslinking temperatures, and the implementation of crosslinking reactions.

As the crosslinked cellulosic fiber, mercerized crosslinked cellulose made by crosslinking in the mercerized cellulose obtained by mercerizing a conventional cellulosic fiber and having a fiber roundness of 0.5 or more can be preferably used. For example, as for mercerized cross-linked cellulose, it is also possible to mercerize a cellulose fiber, such as wood pulp fiber, and increase the roundness of its cross-sectional surface, and then carry out a crosslinking treatment, and marketed mercerized cellulose and crosslink mercerized cellulose for use. As a crosslinked cellulosic fiber, the fiber described in Japanese Patent Application No. 07-255776 A can be used.

The intermediate layer 5 may contain another fibrous material, which is not a crosslinked cellulosic fiber. Examples of other fibrous materials that may be contained in intermediate layer 5 include natural cellulose fiber, such as wood pulp (e.g., softwood sulphate pulp (NBKP) or hardwood sulphate pulp (LBKP)) and non-wood pulp (e.g. cotton pulp and straw pulp); regenerated cellulose fiber, such as viscose or copper-ammonia fiber; hydrophilic synthetic fiber, such as polyvinyl alcohol-based fiber or polyacrylonitrile fiber; and synthetic fibers, such as polyethylene terephthalate (PET) fiber, polyethylene (PE) fiber and polypropylene (PP) fiber, which are hydrophilized with a surfactant. They can be used individually or in the form of a mixture of two or more materials.

The surface density of the fibrous material (all fibrous material, including crosslinked cellulosic fiber) in the intermediate layer 5 is preferably half or more, more preferably single or more, and preferably three times or less, more preferably 2.5 times or less, in particular preferably half up to three times, preferably from one to 2.5 times the surface density of the fibrous material in the absorbent core 40. Thus, when the "surface density in the fibrous material in the intermediate layer 5 / a, the surface density of the fibrous material in the absorbent core 40 "is in the range from 0.5 to 3, the liquid absorption rate is further increased, and the return of the liquid from the intermediate layer 5 is more effectively prevented.

The surface density of the fibrous material (total fibrous material, including crosslinked cellulosic fiber) in the intermediate layer 5 is preferably 50 g / m ² or more, more preferably 100 g / m ² or more, and preferably 300 g / m ² or less, preferably 250 g / m ² or less, in particular, preferably from 50 to 300 g / m ² and more preferably from 100 to 250 g / m ² .

As one of the main distinguishing features of the present utility model, the core wrapping sheet 41 has hydrophilicity, which rarely decreases even when the release / absorption of a biological fluid such as urine is repeated in the process of using the diaper 1, and high permeability to liquids may be maintained. (high liquid penetration rate) for an extended period of time during the use of diaper 1 (i.e., there is hydrophilic stability). In particular, with regard to the core wrapping sheet 41, when the liquid penetration time is repeatedly measured three times or more by the measurement method described below, the liquid penetration time for the first, second and third times is 60 seconds or less, more preferably 50 seconds or less, even more preferably 45 seconds or less. In addition, the lower limit of the liquid penetration time is preferably 5 seconds or more, which time is required to pour 40 g of artificial urine in the measurement method described below, and more preferably 0 seconds or more. Liquid penetration time is an indicator of the liquid penetration rate. Thus, a short liquid penetration time may indicate a high liquid penetration rate, which corresponds to a high rating of excellent liquid permeability. In addition, when the number of measurements in which the liquid penetration time is kept at 60 seconds or less increases, the core wrapping sheet It is praised as having excellent hydrophilic stability. Among the images of special paper and a special hydrophilic non-woven fabric, which are described below, according to an embodiment of the core wrapping sheet 41, there is a sample in which in all measurements from the first to fifth time the liquid penetrates is 60 seconds or less.

Method for measuring liquid penetration time

As illustrated in FIG. 3, two cylinders 91 and 92, having open upper and lower ends and an inner diameter of 35 mm, are mounted vertically, combining the axes of both cylinders 91 and 92, and a filter paper circle (indicated by a conventional number S1 in FIG. 3) having a diameter 55 mm and covering the upper surface of the measured sheet S (wrapping the core of the sheet), in which all sides are 70 mm, is inserted between the upper and lower cylinders 91 and 92. In this case, it is preferable that the clip 93 is attached to the annular flange portion having camping on the lower end of the upper cylinder 91 and the upper end of the lower cylinder 92, and the upper and lower cylinders 91 and 92 are connected to each other. Conventional number 94 denotes an insert made of rubber or a similar material, which includes a through hole having the same inner diameter and the same shape as cylinders 91 and 92. The filter paper used for measurement is a filter paper that holds onto filter particles, according to the standard for filter paper, having a diameter of 1 to 7 μm, and you can use paper selected properly from models numbered 1, 4, 6 and 7, manufactured as commercial products paniey Advantech Co., Ltd. Thus, in the state in which the filter paper S1 and the measuring sheet S are folded together and fixed by the upper and lower cylinders 91 and 92, the artificial urine indicated by the letter W in FIG. 3 is introduced into the upper cylinder 91 by first pouring artificial urine (not illustrated in the drawing) from the container, and 40 g of artificial urine is introduced into the upper cylinder 91 once. The injected artificial urine sequentially penetrates the filter paper S1 and the measured sheet S and flows down from the lower end of the lower cylinder 92, passing through the lower cylinder 92. A time-dependent change in the mass of artificial urine flowing from the lower cylinder 92 is observed using a mass measuring device, such as an electronic balance, a period of time is measured from the moment the introduction of artificial urine begins until the mass reaches 20 g, and this time is defined as the time of liquid penetration. In the case of multiple measurements, each time after the end of the measurement time, water (artificial urine) is removed from the measured sheet S by absorbing water using a water absorbing sheet, etc.

Artificial urine used to measure the time of fluid penetration has the following composition. Urea 1.94 mass. %, sodium chloride 0.7954 mass. %, magnesium sulfate heptahydrate 0.11058 mass. %, calcium chloride dihydrate 0.06208 mass. %, potassium sulfate 0.19788 mass. %, simple polyoxyethylene lauryl ether of 0.0035 mass. % and deionized water (remaining weight).

Due to the stability of the hydrophilicity of the core wrapping sheet 41, the permeability of liquids from the core wrapping sheet 41 to the absorbent core 40 is maintained at a high level even when the release / absorption of the biological fluid is repeated in the process of using the diaper 1, and the absorption properties and the rate of entry (penetration and absorption rate) are increased. fluid) biological fluid into the absorbent core 40 (bottom layer). As a result of this, the amount of residual liquid in the intermediate layer 5 is effectively reduced (the intermediate layer 5 contains a hydrophilic fiber (crosslinked cellulose fiber)) located on the skin side of the surface of the absorbent core 40. In addition, the biological fluid can be removed from the skin of the wearer of the diaper 1 due to the high permeability with respect to the liquids of the core wrapping sheet 41, and liquid return is effectively reduced. Due to the synergistic effect of the intermediate layer 5 containing crosslinked cellulosic fiber and wrapping the core of the sheet 41 having hydrophilic stability, the diaper 1 has excellent liquid permeability, has a high liquid penetration / absorption rate, and residual liquid accumulation and return rarely occurs therein. liquids.

As the core-wrapping sheet 41, paper having hydrophilic stability or a hydrophilic non-woven fabric can be used. In particular, it is possible to use special paper or a special hydrophilic non-woven fabric, which are described below. Next, special paper and a special hydrophilic non-woven fabric will be sequentially described.

Special paper

As for special paper, bleached softwood sulphate pulp having a grinding degree of 400 to 550 ml is used as the main material, two or more types of paper hardening agents are added, the surface density is 10 to 14.5 g / m ² , the density is 0, 05 to 0.2 g / cm ³ and the degree of creping is 5 to 30%. Next, special absorbent paper will be described.

Special paper contains bleached softwood sulphate pulp (NBKP), having a degree of grinding from 400 to 550 ml, as an obligatory component. The degree of grinding is preferably 475 ml or more, more preferably 490 ml or more, and preferably 525 ml or less, more preferably 510 ml or less, in particular, preferably 475 to 525 ml and more preferably 490 to 510 ml. The degree of grinding is a value that is described as the Canadian standard degree of grinding (C.S.F.) and is defined in JIS P8121; this value shows the degree of milling of cellulose (treatment of cellulose by mechanical action and grinding in the presence of water). The NBKP can be milled using paper feed stock (slurry), and during the milling process, the NBKP is dispersed in a conventional manner using a known milling machine, such as a milling machine or a disk mill. As a rule, the smaller the degree of grinding, the more intense the grinding, and the greater the destruction of the fiber in the grinding process, and thus, the separation into fibers. As for NBKP, in which the degree of grinding is in a predetermined interval, the separation is carried out into fibers, and thus the fibers are easily intertwined with each other. For this reason, even when the number of connection points between the constituent fibers is reduced by lowering the surface density of the thin paper in order to increase liquid permeability, the bond strength between the respective fibers is high compared to NBKP, in which the degree of grinding exceeds 550 ml, and fiber separation is carried out to a lesser extent. Thus, special paper in which the base material is NBKP having a grinding degree of 400 to 550 ml can have favorable strength characteristics.

As for special paper, its main material is NBKP, in which the degree of grinding is from 400 to 550 ml. Here, the term "base material" means that the percentage of NBKP having a degree of grinding in a given interval is 50 mass. % or more. In order to obtain excellent strength characteristics, the percentage is preferably 50 mass. % or more, preferably 80 mass. % or more, and preferably 100 mass. % or less, in particular, preferably from 50 to 100 mass. % and preferably from 80 to 100 mass. %

The roughness of the NBKP fibers used for special paper is preferably 0.1 mg / m or more, more preferably 0.12 mg / m or more, and preferably 0.2 mg / m or less, more preferably 0.18 mg / m or less in particular, preferably from 0.1 to 0.2 mg / m, and more preferably from 0.12 to 0.18 mg / m. The fiber roughness is used as a value indicating the thickness of the fiber in the case of fibers having a non-uniform thickness, such as wood pulp. In addition, the average length of NBKP fibers used for special paper is preferably 1 mm or more, more preferably 2 mm or more, and preferably 4 mm or less, more preferably 3 mm or less, in particular, preferably 1 to 4 mm and more preferably from 2 to 3 mm. Each of the values, including fiber roughness and average fiber length, is measured as described below.

Measurement of fiber roughness and average fiber length

The measurement is carried out using an FS-200 fiber roughness meter (manufactured by KAJAANI ELECTRONICS LTD.). Fiber (cellulose) is not subjected to grinding before measurement.

First, to determine the true mass of the measured fiber, the fiber is dried in a vacuum dryer at 100 ° C for an hour, and the water present in the fiber is removed. Thus, an accurate sample containing 1 g of dried fiber (with an accuracy of ± 0.1 mg) is used for measurement. After that, the fiber sample is completely deaggregated in 150 ml of water, using a mixer in the fiber roughness meter, so as not to destroy the fiber as much as possible, and the fiber, which is deaggregated in water, is diluted with water to obtain a dilute solution, the total volume of which is 5000 ml. A volume of 50 ml is accurately measured from the resulting diluted solution, and this volume of 50 ml of the diluted solution is used as a solution for measuring fiber roughness. Each value, including the determined fiber roughness and average fiber length, is calculated in accordance with the working procedure of the fiber roughness meter. In this case, the value calculated according to the following equation 1 on the basis of this working procedure is used in the calculations as the average fiber length.

Here n _i represents the number of fibers whose length is l _i ; l _i represents the length of the fiber.

Special paper may contain other types of fibers that are not NBKP, and these other fibers may not be a hydrophilic cellulosic fiber such as NBKP. Examples of other fibers are wood pulp, such as hardwood bleached sulfate pulp (LBKP), softwood bleached sulfite pulp (NBSP), or thermomechanical pulp (TMP); bast fiber, such as fiber of paper tree, fiber of Japanese (paper) birch (Betula papyrifera) or fiber of shrubbery of the ganpi genus (Wikstromia, Wikstroemia); cellulose from non-wood sources such as straw, bamboo, kenaf or hemp; synthetic fiber, such as polyester fiber, viscose yarn or acrylic fiber. The percentage of other fibers is preferably 50 mass. % or less.

To obtain excellent strength characteristics (tensile strength), paper-reinforcing substances of two or more types are added to special paper. Paper hardening agents include dry paper hardening agents that increase dry paper strength and wet paper hardening agents that increase wet paper strength. As paper reinforcing substances of two or more types, it is possible to select dry paper reinforcing substances and wet paper reinforcing substances of two or more types. However, in particular, in order to obtain excellent strength characteristics, it is preferable to use a combination of a hardening dry paper substance of one or more types and a hardening wet paper substance of one or more types.

As a dry paper hardening agent, a conventionally known dry paper hardening agent can be used. Exemplary dry paper hardening agents are carboxymethyl cellulose (CMC) and the corresponding salt, a polyacrylamide-based polymer and the corresponding salt, cationized starch, polyvinyl alcohol (PVA), etc. It turns out that it is possible to use one type of a dry paper reinforcing substance or a combination of two or more types of dry paper strengthening a paper. The sodium salt is mainly used as a salt of each of the substances, including CMC and a polyacrylamide-based polymer. Exemplary polyacrylamide-based polymers are cationic or anionic polyacrylamide (PAM). In particular, it is preferable to use CMC and the corresponding salt and anionic PAM and the corresponding salt as hardening dry paper substances.

As a wet paper hardener, a conventionally known wet paper hardener can be used. Exemplary wet paper hardening agents are epoxidized polyamide polyamine polymer (PAE), urea formaldehyde polymer, melamine formaldehyde polymer, dialdehyde starch, polyethyleneamine, methylated polyamide, etc. It turns out to be possible to use one type of wet paper reinforcing substance or a combination of two or more types of wet paper reinforcing substances. In particular, it is preferable to use PAE as a hardening wet paper substance.

A particularly preferred combination of paper hardening agents in special paper are two types of dry paper hardening agents of the same type, one wet type hardening paper. Among the paper reinforcing agents of these three types, a CMC salt and anionic PAM salt are preferred as two types of dry paper reinforcing substances, and PAE is preferred as one type of wet paper reinforcing substance.

The total amount of added paper reinforcing substances of two or more types in a special paper is preferably 0.01 mass. % or more, preferably 0.03 mass. % or more, and preferably 1.5 mass. % or less, preferably 1.2 mass. % or less, in particular, preferably from 0.01 to 1.5 mass. % and preferably from 0.03 to 1.2 mass. % relative to the dry weight of the entire fiber constituting special paper. When the total amount of paper reinforcing agents added is excessively small, strength characteristics such as tensile strength are not sufficiently achieved. When the total amount of paper reinforcing substances added is excessively large, the problem arises that the production of special paper is disrupted due to the paper sticking to the American tumble dryer and adhesion of the paper reinforcing substance to the mesh drum during the manufacturing of special paper, in addition to hardening of special paper (texture deterioration).

Special paper may contain another component that is not a fiber, such as NBKP and paper hardening substance, which is described above. Examples of another component are those components typically used as starting material for making paper, or additives, such as a filler, including talc, dye, color pigment, antimicrobial agent, pH adjuster, retention aid, waterproof additive or antifoam. It is possible to use a component of one type or a combination of components of two or more types.

Special paper can be made using a known wet paper manufacturing process. A wet paper manufacturing process includes a paper manufacturing process for making paper that uses such a starting material (slurry) containing an aqueous dispersion of a fiber such as NBKP, and a paper manufacturing process by drying a fibrous web that forms a fiber made from a raw material for paper while moving the fibrous web. Typically, the papermaking process comprises a mesh part, a press part, a drying part, an adhesive part, a calendaring part, etc., which are carried out sequentially. The dry paper hardener and the wet paper hardener as described above are typically added to the paper feed during the manufacturing process of the paper feed. Typically, a wet paper hardener and a dry paper hardener are added to the paper source material in exactly this order.

However, the sequence for adding paper reinforcing agents according to the present utility model is not limited to this. The sequence of addition can be determined in another way, and substances of these two types can be added simultaneously. For example, the wet paper making process can be carried out in a conventional manner using a paper making machine, such as a Fourdrinier long mesh paper machine, a double mesh paper machine, a bulk paper machine, a hybrid paper machine or a cylinder paper machine.

As for special paper, surface density and density are set at relatively low levels in order to increase permeability to liquids. In particular, the surface density of special paper is preferably 10 g / m ² or more, more preferably 11 g / m ² or more, and preferably 14.5 g / m ² or less, more preferably 14 g / m ² or less, in particular preferably from 10 to 14.5 g / m ² and more preferably from 11 to 14 g / m ² . In addition, the density of special paper is preferably 0.05 g / cm ³ or more, more preferably 0.1 g / cm ³ or more, and more preferably 0.2 g / cm ³ or less, in particular preferably from 0.05 up to 0.2 g / cm ³ and more preferably from 0.1 to 0.2 g / cm ³ . Thus, when the surface density and density are low, paper strength can be reduced. However, according to the present utility model, as described above, paper strength may not be reduced by using NBKP having a degree of grinding in a predetermined interval and using two or more types of paper hardening agents. When the surface density of special paper is less than 10 g / m ² , or its density is less than 0.05 g / cm ³ , paper strength can be significantly reduced. In addition, when the surface density of special paper exceeds 14.5 g / m ² , or its density exceeds 0.2 g / cm ³ , there may be no effect of increasing permeability with respect to liquids.

The surface density of special paper is measured as described below. After the product (special paper) is subjected to humid conditioning according to the JIS P8111 standard, a square measurement sample is cut from the product with a side of 10 cm (area 100 cm ² ), the mass of the measured sample is measured using weights to the accuracy two decimal places, and the surface density of the measured sample is calculated by dividing the measured mass by the area of the sample. The surface density is calculated by measuring 10 samples cut from the measured product, and the obtained average value is determined as the surface density of this product.

In addition, the density of special paper is measured as described below. Ten square samples of special paper, on which all sides are 20 cm, are laid on top of each other to obtain a multilayer product, this multilayer product is cooled and cured using liquid nitrogen, and then the middle part of the multilayer product is cut with a knife. From ten samples, a sample is selected in which the cross-sectional surface formed by cutting with a knife does not move, and the thickness of the selected sample is measured using an optical microscope. The thickness of the sample corresponds to the length (actual thickness) of the part where the component fiber is applied, and not the length (apparent thickness) from the lowest part to the topmost part in the recesses and bulges when there are recesses and bulges in the sample, such as in the case of creping, which described below. The mass W of a square sample, whose sides are 20 cm, and the thickness is measured as described above, is determined using a scale with an accuracy of two decimal places. The desired density is calculated by dividing the mass W of the sample by the volume V of the sample calculated by the formula below (i.e., as the W / V ratio). In the formula below, T represents the thickness (cm) of the sample, A represents the degree of creping (%) of the sample, and B represents the length (20 cm) of the side of the sample. As described below, special paper includes creping, and its degree of creping is measured as follows.

Special paper includes creping (creases in the form of small roughness), and its creping degree is from 5 to 30%. It is preferable that the creping of special paper is a dry creping, which is formed when the fibrous web (special paper) is peeled off in a dried state after an American drum dryer or similar device in the dryer section with a doctor blade, etc. The degree of creping is measured as described below.

The method of measuring the degree of creping

A rectangular fragment with dimensions of 200 mm in the length direction (direction of movement during the production of special paper or machine direction, MD) and 100 mm in the width direction (perpendicular to machine direction or transverse direction, CD) is cut from the measured sheet (special paper ) and is used as a sample. The length C in the machine direction is measured immediately after the rectangular-shaped sample is held in water for 10 minutes, and the degree of creping is calculated by the formula below.

For example, when the length C in the machine direction after keeping for 10 minutes is 220 mm, the degree of creping of special paper, calculated according to the above formula, is 10%.

Crepe paper has a higher permeability to liquids than paper that does not have a crepe. In addition, when the degree of creping increases, the permeability with respect to liquids also increases. However, when the degree of creping increases, as a rule, the strength characteristic (tensile strength) deteriorates. According to the present utility model, the degree of creping of special paper is from 5 to 30% in terms of the balance between permeability with respect to liquids and strength characteristics based on the information provided. The degree of creping of special paper is preferably 5% or more, more preferably 7% or more, and preferably 20% or less, more preferably 15% or less, in particular, preferably 5 to 20% and more preferably 7 to 15%.

Special hydrophilic non-woven fabric

The special hydrophilic non-woven fabric contains a synthetic fiber mixed with a hydrophilizing substance, including a synthetic polymer, with which the hydrophilizing substance is pre-mixed, as a fibrous starting material. That is, a synthetic fiber mixed with a hydrophilizing substance is obtained, a synthetic polymer is processed into a fiber with which the hydrophilizing substance is pre-mixed, and the “fiber obtained by applying a hydrophilizing substance to the fiber surface by spraying and coating with a solution of hydrophilizing substance on the fiber surface differs from it, made of synthetic polymer. " A synthetic fiber mixed with a hydrophilizing agent has such a distinguishing feature that the hydrophilizing agent rarely escapes even when a biological fluid such as urine is re-poured and the hydrophilicity is rarely reduced.

A variety of known hydrophilizing agents can be used without particular limitation. For example, a hydrophilic oil solution is used. As a hydrophilic oil solution, as a rule, an anionic, cationic, simultaneously anionic and cationic or nonionic surfactant is used. However, the hydrophilic oil solution is not limited in a particular way. As a hydrophilic oil solution, an aqueous solution, a liquid emulsion and a similar liquid having a predetermined concentration can be used. Examples of a preferred hydrophilizing agent are a salt of a fatty monocarboxylic acid, a polyoxyethylene alkyl sulfate, a salt of a polyoxyethylene alkylphosphoric acid, a glycerol fatty acid ester, a sorbitol fatty acid ester, a sucrose fatty acid ester, a polyoxyethylene alkyl ether, a polyethylene glycol alkyl ester and alkyl betaine. One type of hydrophilizing agent may be used, or a combination of two or more types of hydrophilizing agent may be used.

A variety of known synthetic polymers suitable as a material for the manufacture of a synthetic fiber mixed with a hydrophilizing agent can be used without any limitation. Exemplary polymers are a polyolefin based polymer such as polyethylene and polypropylene, as well as a polyester based polymer such as polyethylene terephthalate. It is possible to use a polymer of one type or a combination of polymers of two or more types. In addition, the synthetic fiber mixed with the hydrophilizing agent may be a monofilament containing a polymer mixed with it, which is a synthetic polymer of the same type or a combination of synthetic polymers of two or more types, and the fiber may be a multicomponent fiber. Multicomponent fiber means a synthetic fiber obtained by combining synthetic polymers of two or more types, and containing various components, using a die and simultaneously spinning, and means a synthetic fiber in which many components are connected to each other in the structure of one fiber, each of which many components is continuous in the longitudinal direction of the fiber. Exemplary multicomponent fiber structures are core-sheath structures and parallel component types, and they are not limited in a particular way.

The shape of a special hydrophilic non-woven fabric (type of non-woven fabric) is not limited in a specific way. Suitable examples include a single layer nonwoven fabric, such as a breathable nonwoven fabric, a hot rolled nonwoven fabric, a spunbond nonwoven fabric, a polymer bonded nonwoven fabric, needle-punched non-woven fabric, a hydro-woven non-woven fabric, or an air-laid non-woven fabric. The surface density of the special hydrophilic non-woven fabric is preferably 5 g / m ² or more, more preferably 10 g / m ² or more, and preferably 30 g / m ² or less, more preferably 20 g / m ² or less, particularly preferably from 5 up to 30 g / m ² and more preferably 10 to 20 g / m ² .

When a special hydrophilic non-woven fabric is used as the core-wrapping sheet 41, this core-wrapping sheet 41 may further comprise another non-woven fabric (for example, a conventional non-woven fabric that lacks hydrophilicity) as an addition to the special hydrophilic non-woven fabric, and a special hydrophilic non-woven fabric and another non-woven fabric can be laminated and bonded to each other. Specific examples of the core-wrapping sheet 41 using a special hydrophilic non-woven fabric include a sheet in which an SMS non-woven fabric is present (a non-woven fabric in which a layer of a spunbond nonwoven web, a layer of aerodynamic nonwoven web and a layer of spunbond nonwoven are sequentially laminated and bonded to each other web), and a layer of spunbond nonwoven fabric that forms at least one surface of the nonwoven fabric is a special hydrophilic nonwoven fabric ( won hydrophilizing agent intermixed with synthetic fibers, wherein the synthetic polymer is premixed with a hydrophilizing agent, is used as the fiber starting material). Other examples of core wrapping sheet 41 include a nonwoven fabric SM (a nonwoven fabric in which a layer of aerodynamic nonwoven fabric and a layer of spunbond nonwoven fabric are laminated and bonded to each other).

According to a preferred embodiment, examples of a core-wrapping sheet 41 including an SMS non-woven fabric containing a special hydrophilic non-woven fabric are Type A and Type B described below. In particular, Type A is preferred. Type A is a type in which spunbond nonwoven webs forming both surfaces of the SMS nonwoven web constitute a special hydrophilic nonwoven web. Type B is a type in which only a spunbond nonwoven web forming the surface of the SMS nonwoven web constitutes a special hydrophilic nonwoven web. In the case of type B, it is preferable that the core wrapping sheet 41 including the SMS nonwoven fabric is arranged in the diaper 1 in such a way that the spunbond nonwoven fabric, which constitutes the special hydrophilic nonwoven fabric, forms a surface facing the skin (opposite surface of the intermediate layer 5) of the wrapping core sheet 41.

SMS non-woven fabric containing a special hydrophilic non-woven fabric can have a low surface density due to its high wet strength and also has excellent liquid permeability regardless of the presence of hydrophilization of another layer, which is not a special hydrophilic non-woven fabric. On the other hand, since the wet strength of the core-wrap sheet 41 is high for deformation of the absorbent element upon return of the liquid, and a large amount of liquid moves due to deformation, the effect of slowing the rapid movement of the liquid in the SMS nonwoven fabric (including a layer of aerodynamic nonwoven fabric having narrow the space between the fibers) by preventing splitting and tearing due to deformation of the absorbent element. According to an embodiment, in the SMS nonwoven fabric, the core wrapping sheet 41 is not hydrophilized for another layer that is not a special hydrophilic nonwoven fabric. However, when the respective layers contained in the SMS non-woven fabric are laid in the state of the fabric and connected to each other in a state in which the respective layers are attached to each other, it is considered that part of the hydrophilizing substance emerging (to the extent that stability is not compromised) on the surface of the fibers of a special hydrophilic non-woven fabric, moves to the surface of the fibers of another layer, and as a result, the other layer turns into a hydrophilic layer, and the permeability increases with respect to liquids.

In order to obtain high permeability to liquids and at the same time maintain sufficient wet strength, the surface density of SMS non-woven fabric containing a special hydrophilic non-woven fabric is preferably 5 g / m ² or more, more preferably 8 g / m ² or more, and preferably 30 g / m ² or less, more preferably 20 g / m ² or less, in particular, preferably 5 to 30 g / m ² and more preferably 8 to 20 g / m ² . In addition, the strength of the SMS non-woven fabric, which contains a special hydrophilic non-woven fabric, is preferably 2 N or more and more preferably 3 N or more. Wet strength is measured as described below.

The method of measuring strength in the wet state

A rectangular measured sample, the dimensions of which is 200 mm in the longitudinal direction of the absorbent product (direction of movement during manufacturing of the measured sheet or machine direction, MD) and 50 mm in the width direction of the absorbent product (perpendicular to the machine direction or transverse direction, CD), is cut from the measured sheet (wrapping the core of the sheet), and the measured sample is immersed in the water in the vessel, so that the measured sample absorbs a sufficient amount of water and then the excess water is removed by slightly compressing the sample to be measured between the layers of a water-absorbing material, such as a paper towel, and a measurement sample is obtained. The measured sample is attached to the clamps of a tensile testing device (such as, for example, a Tensilon RTA-100 tensile testing device manufactured by Orientec Co., Ltd.) with a clamp distance of 150 mm, so that the longitudinal direction (MD) is the direction of extension. After that, the measured sample is stretched at a tensile speed of 300 mm / min, and the maximum value of the load (tensile strength) is measured at which the measured sample is torn, and this value is defined as the strength of the measured sample in the wet state.

As illustrated in FIG. 1 and 2, to further describe another component of the diaper 1, which is not a core-wrap sheet 41, a liquid-permeable underlayer (backing sheet) 6 is located between the top sheet 2 and the intermediate layer 5. The liquid-permeable backing sheet 6 is a sheet, including paper, non-woven fabric and other materials that differ from the materials of the absorbent element 4 and the intermediate layer 5, and is also called the term "backing sheet". The liquid-permeable backing sheet 6 effectively reduces the so-called liquid return, in which the liquid absorbed in the absorbent element is returned to the top sheet. A liquid-permeable backing sheet 6 is located in the crotch portion C, covering at least the target area. According to an embodiment, as illustrated in FIG. 1, the liquid-permeable backing sheet 6 occupies a position covering almost the entire area of the intermediate layer 5. Similarly to the intermediate layer 5, the liquid-permeable backing sheet 6 has a rectangular shape in a plan view. However, the liquid-permeable backing sheet 6 is longer in the width direction Y than the intermediate layer 5, and also has a larger width than the intermediate layer 5. The liquid-permeable backing sheet 6 is fully or partially attached to each sheet, including the upper sheet 2 and the intermediate layer 5, using glue.

As a liquid-permeable backing sheet 6, for example, wet-made paper can be used, as well as a variety of non-woven webs, such as a carded non-woven, breathable non-woven, polymer bonded non-woven, spunbond non-woven, aerodynamic non-woven canvas, hydrostatic nonwoven fabric and needle-punched nonwoven fabric. These nonwoven webs can be hydrophilized using a hydrophilizing agent, such as a surfactant. The surface density of the liquid-permeable backing sheet 6 is preferably 20 g / m ² or more, more preferably 30 g / m ² or more, and preferably 70 g / m ² or less, more preferably 50 g / m ² or less, particularly preferably from 20 to 70 g / m ² and more preferably from 30 to 50 g / m ² .

As the top sheet 2, a liquid permeable sheet conventionally used in the art can be used. Suitable examples are a variety of non-woven webs, such as a carded non-woven fabric, a breathable non-woven fabric, a spunbond nonwoven fabric, an aerodynamic non-woven fabric, a hydro-woven non-woven fabric, and needle-punched non-woven fabric; as well as a film that allows liquid to penetrate through the holes. Nonwoven webs and film can be hydrophilized using a hydrophilizing agent, such as a surfactant. In terms of cost, performance, and absorption properties, the surface density of the top sheet 2 is preferably 10 g / m ² or more, more preferably 15 g / m ² or more, and preferably 60 g / m ² or less, more preferably 50 g / m ² or less, in particular, preferably from 10 to 50 g / m ² and more preferably from 15 to 50 g / m ² .

It turns out that Vaseline is applied to the top sheet 2. The top sheet 2 is a component that comes into contact with the skin of the wearer of the diaper 1, and a skin care effect can be expected when petroleum jelly is applied to the top sheet 2. In particular, it is effective when petroleum jelly is applied to the skin side of the surface of the top sheet 2 As a petroleum jelly, you can use a moisturizer and a material used for skin care, without specific restrictions. Exemplary methods for applying petroleum jelly to the top sheet include a method for applying or spraying a petroleum jelly solution, in which petroleum jelly dissolved in an appropriate solvent is applied to the top sheet. The amount of petroleum jelly solution that is applied to the top sheet, in terms of solid, is preferably 5 g / m ² or more, more preferably 10 g / m ² or more, and preferably 30 g / m ² or less, more preferably 20 g / m ² or less, in particular, preferably from 5 to 30 g / m ² and more preferably from 10 to 20 g / m ² .

As the bottom sheet 3, it is possible to use, for example, a variety of liquid-impermeable or water-repellent sheets, such as a polymer film that is water resistant, a polymer film having micropores and moisture permeability, a non-woven fabric, such as a water-repellent non-woven fabric, and a lamination product of one sheet and another sheet. In addition, a sheet similar to the bottom sheet 3 can be used as the side sheet 7.

In this regard, according to the present utility model, the top sheet 2A (uneven top sheet) having a concave-convex shape, which is illustrated in FIG. 4 and 5, instead of a flat top sheet 2 (top sheet is a flat type), which has virtually no bumps. As illustrated in FIG. 4 and 5, the topsheet 2A includes multiple bumps 21 protruding toward the skin of the wearer and numerous indentations 22 adjacent to the bumps 21. The bumps 21 and the indentations 22 are alternately located on the skin surface 2a of the top sheet 2A, which is the skin-facing the surface of the diaper 1, and form a directional line. The concave-convex shape of the skin-facing surface 2a of the top sheet 2A, which comprises the bulges 21 and the recesses 22, is formed at least in the location region (as illustrated in FIG. 1, the area overlapping the absorbent element 4 in a top view of the diaper 1 , that is, the middle part in the width direction Y of the diaper 1) of the absorbent element 4 in the crotch part C (target area), and also forms in the location area of the absorbent element 4 in each part, including the back part A and the front part B, according to ntu implementation.

The top sheet 2A includes a nonwoven fabric having a single layer structure. The top sheet 2A protrudes toward the user's skin in a part that is not a recess 22 and forms a bulge 21. A space 25 in which there is practically no material from which the top sheet 2A is made is formed inside the bulges 21. The recesses 22 are almost flat without irregularities and come into contact with the surface of the absorbent element 4 facing the skin (core wrapping sheet 41). The top sheet 2A having an uneven structure, which is formed by the bulges 21 and the recesses 22, can be made using a known embossing method. For example, the top sheet 2A is made by placing the original top sheet web (a flat sheet in which there are no bumps) on the contact portion of the first roller, in which the peripheral surface has a concave-convex shape, and a second roller having a concave-convex shape of the peripheral surface, which combined with the concave-convex shape of the first roller, and stamping is carried out on the original canvas of the top sheet.

When the top sheet 2A is used instead of the top sheet 2 in the diaper 1, the permeability of the top sheet 2A is increased and there is practically no return of liquid compared to a flat top sheet which has no irregularities on the surface (surface facing the skin) since the bulges 21 are turned to the side skin, and a space 25 is formed in which there is practically no material from which the top sheet 2A is made, and the efficiency is that the amount of biological fluid 5, which I remains on the skin and feeling of dryness is enhanced when touching the surface (facing the skin surface) is relatively reduced because the contact area with the skin.

In order to more reliably implement the above-described effect, which causes the top sheet 2A, it is preferable that the dimensions and other parameters of each part of the top sheet 2A are as described below.

The height L1 of the bulges 21 (see FIG. 5) is preferably 0.5 mm or more, more preferably 1 mm or more, and preferably 6 mm or less, more preferably 5 mm or less, in particular preferably from 0.5 to 6 mm and more preferably 1 to 5 mm.

The maximum diameter L2 of the bulges 21 (see FIG. 5) is preferably 1 mm or more, more preferably 0.5 mm or more, and preferably 10 mm or less, more preferably 5 mm or less, in particular preferably 1 to 10 mm and preferably from 0.5 to 5 mm.

Furthermore, according to the present utility model, an absorbent core 40A (an uneven absorbent core) having a concave-convex shape, which is illustrated in FIG. 6A and 6B, rather than a flat absorbent core 40 (flat type absorbent core), which has virtually no irregularities. As illustrated in FIG. 6, the absorbent core 40A includes a high density portion 43 having a relatively high content of absorbent material and a low density portion 42 having a relatively low content of absorbent material, the high density portion 43 and the low density portion 42 being alternately in a predetermined direction. In the form illustrated in FIG. 6, the high-density part 43 and the low-density part 42 are arranged alternately in each direction, including the longitudinal direction X and the direction of width Y. In particular, as illustrated in FIG. 6, in the absorbent core 40A, there are numerous linear low density portions 42X extending along the entire length in the longitudinal direction X of the absorbent core 40A, and numerous linear low density portions 42Y extend along the entire length in the width direction Y of the absorbent core 40A, and the generally low density portion 42 made in the form of a lattice. The portion that the linear low-density portions 42X and 42Y share is a high-density portion 43. Each of the plurality of high-density portions 43 has a rectangular shape in a plan view.

As illustrated in FIG. 6, the high-density portion 43 has a greater thickness than the low-density portion 42 (42X and 42Y). For this reason, the absorbent core 40A has a concave-convex shape in which the high-density portion 43 protrudes with respect to the low-density portion 42. When the absorbent core 40A has a concave-convex shape, it is easier to deform the absorbent core 40A (absorbent member 4) while wearing the diaper. 1, in particular, a change in the shape of the absorbent core 40A protruding towards the skin of the wearer of the diaper compared to an absorbent core that does not have a concave-convex shape and in which giving the surface, including the surface facing the skin and the surface not facing the skin, is almost flat, like the absorbent core 40. The target area in the crotch portion C is easily deformed when the wearer of the diaper is pressed against the skin while wearing the diaper 1 due to the easily deformed absorbent core 40A. In this way, the fit is improved and the wearer feels comfortable to wear the diaper, and the leakage of body fluid such as urine is effectively prevented.

The low density portion 42 (42X and 42Y) is located in the thickness direction of the absorbent core 40 in a sectional view of the absorbent core 40A, as illustrated in FIG. 6 (b). In particular, as illustrated in FIG. 6, the low-density portion 42 is located on the skin-facing side of the surface 40b in the thickness direction T of the absorbent core 40A. Thus, when the low-density portion 42 is located on the skin-facing side of the surface 40b in the thickness direction T, the high-density portion 43 projects in the opposite direction to the skin-facing surface 40b, i.e., the non-skin-facing side of the surface 40a in the thickness direction T. Thus , in the absorbent core 40A, the skin-facing surface 40b is almost flat and there are practically no irregularities on it, and the non-skin-facing surface 40a has irregularities because the high-density part 43 (bulge) has t protruding shape, and the low-density part 42 (no bulge or recess) is located between the high-density parts 43 and 43.

When the absorbent core 40A is used instead of the absorbent core 40 in the diaper 1, and the absorbent core 40A includes a low density portion 42, and the formed recess (the space in which there is no material from which the absorbent core 40A is made) corresponds to the low density portion 42, the absorbent core 40A may be effectively used by dispersing biological fluid while reducing the absorption time of biological fluid. Accordingly, liquid return is more effectively prevented.

In order to more reliably implement the above effect that the absorbent core 40A provides, it is preferred that the dimensions and other parameters of each part of the absorbent core 40A are as described below.

The ratio (S42 / S41) of the surface density S42 of the low density portion 42 and the surface density S41 of the high density portion 43 of the absorbent core 40A is preferably 20% or more, more preferably 30% or more, and preferably 80% or less, more preferably 70% or less, in particular preferably from 20 to 80% and more preferably from 30 to 70%.

The surface density S41 of the high-density portion 43 is preferably 300 g / m ² or more, more preferably 350 g / m ² or more, and preferably 900 g / m ² or less, more preferably 800 g / m ² or less, in particular preferably from 300 up to 900 g / m ² and more preferably 350 to 800 g / m ² .

The surface density S42 of the low density portion 42 is preferably 100 g / m ² or more, more preferably 150 g / m ² or more, and preferably 500 g / m ² or less, more preferably 400 g / m ² or less, in particular preferably from 100 up to 500 g / m ² and more preferably from 150 to 400 g / m ² .

The ratio (T42 / T41) of the thickness T42 of the low density portion 42 and the thickness T41 of the high density portion 43 is preferably 30% or more, more preferably 40% or more, and preferably 90% or less, more preferably 80% or less, in particular preferably 30 to 90% and preferably from 40 to 80%.

The thickness T41 of the high density portion 43 is preferably 2 mm or more, more preferably 3 mm or more, and preferably 8 mm or less, more preferably 7 mm or less, in particular preferably 2 to 8 mm and more preferably 3 to 7 mm.

The thickness T42 of the low-density portion 42 is preferably 1.5 mm or more, more preferably 2.5 mm or more, and preferably 4.5 mm or less, more preferably 4 mm or less, in particular preferably 1.5 to 4.5 mm and more preferably 2.5 to 4 mm.

It is preferable to control the ratio of the area of the high-density part 43 and the area of the low-density part 42 in the absorbent core 40A. In particular, the ratio of the area of the high-density part 43 to the area of the low-density part 42 is preferably from 6: 4 to 9: 1, and more preferably from 7: 3 to 8: 2.

The concave-convex absorbent core 40A can be manufactured using a known fiber laminating device in a manner similar to the manufacturing method of the absorbent core type of the absorbent article. Typically, a fiber laminating device is equipped with a rotary drum including an accumulation recess on the circumferential surface, and it is a device that directs the absorbent material in a dispersed state to the circumferential surface while rotating the rotary drum, and places the absorbent material in the accumulation recess by suction bottom of the accumulation cavity, removes the laminated fibrous material from the accumulation cavity by suction by a suction device, which is located facing the recess for accumulation, and moves the laminated fibrous material on the suction device. When the lower part is occupied by an impermeable or low permeable element by placing an impermeable or low permeable element in a part of the permeable bottom of the recess for accumulation in the fiber laminating device having such a configuration, the absorbent material rarely fits into the impermeable or low permeable part when laying the absorbent material, and the amount of absorbent material, laid in an impermeable or poorly permeable part, is small compared to another part of the bottom. Thus, when the absorbent core is manufactured in the usual way using a fiber laminating apparatus equipped with a rotary drum, in which the lower part of the storage cavity is an impermeable or low permeable part, the part corresponding to an impermeable or low permeable part is a low density part 42 (42X and 42Y), and the part corresponding to the other lower part is the high-density part 43, and thus an absorbent heart is obtained ina 40A, having a concavo-convex shape.

Next, the present utility model will be described based on a preferred embodiment. However, the present utility model is not limited to this embodiment. For example, according to an embodiment, the absorbent core 40 is coated using one part of the core wrapping sheet 41. However, two core wrapping sheets can also be used to cover the skin-facing surface of the absorbent core 40 (the surface facing the intermediate layer 5) with one of two wrapping the core of the sheets, and cover the surface of the absorbent core 40 not facing the skin (surface facing the bottom sheet 3) with another sheet. In this case, the core wrapping sheet covering at least the skin-facing surface of the absorbent core may have hydrophilic stability, which ensures that the first, second and third times the liquid penetration time is 60 seconds or less in the method of measuring a predetermined penetration time liquid, as described above, and the core-wrapping sheet covering the non-skin surface of the absorbent core may lack hydrophilicity stability.

In addition, according to an embodiment of the present utility model, a so-called experimental disposable diaper is provided as an applied example of an absorbent article. However, it is possible to use an absorbent article as a sanitary napkin, a napkin attached to the underwear of an incontinence pad, and the like, in addition to a disposable diaper immediately made in the form of underwear. All parts that are provided only according to the above described embodiment may be used in combination appropriately.

The following is an additional note regarding an absorbent article, which is discussed in detail in connection with the above embodiment of the present utility model.

1. An absorbent article comprising a liquid-permeable topsheet on the skin side of the surface, a liquid-impermeable topsheet on the non-skinned side of the surface, and an absorbent member located between these sheets and including an intermediate layer located between the topsheet and the absorbent member ,

wherein the intermediate layer comprises a crosslinked cellulosic fiber, the absorbent element includes an absorbent core containing absorbent material, and a core wrapping sheet covering at least the skin-facing surface of the absorbent core and containing paper or a hydrophilic non-woven fabric, and

the liquid penetration time for the first, second and third time is 60 seconds or less when measuring the liquid penetration time three or more times by the measurement method described below with respect to the core wrapping sheet.

Method for measuring liquid penetration time

Two cylinders having open upper and lower ends and an inner diameter of 35 mm are installed vertically, combining the axes of both cylinders, and a circle of filter paper having a diameter of 55 mm and covering the upper surface of the measured sheet (wrapping the core of the sheet), which has all sides 70 mm, inserted between the upper and lower cylinders. In this position, 40 g of artificial urine is introduced into the upper cylinder. Introduced artificial urine sequentially penetrates through the filter paper and the measured sheet and flows down from the lower end of the lower cylinder, passing through the lower cylinder. A time-dependent change in the mass of artificial urine flowing down from the lower cylinder is observed, a period of time is measured from the moment the introduction of artificial urine begins until the mass reaches 20 g, and this time is determined as the time of liquid penetration.

2. The absorbent product according to claim 1, wherein the core wrapping sheet comprises a spunbond - aerodynamic - spunbond layers nonwoven fabric, and a spunbond nonwoven fabric forming at least one surface of the nonwoven fabric, contains a synthetic fiber mixed with a hydrophilizing substance, in which a synthetic polymer pre-mixed with a hydrophilizing substance is used as a fibrous starting material.

3. The absorbent article according to claim 1 or 2, wherein the core wrapping sheet has a width of not less than two and not more than three times in the width direction of the absorbent core, and the entire area of each surface, including the surface of the absorbent core facing the skin and not reversed to the skin, the surface of its opposite side, covers one detail of the core wrapping sheet.

4. The absorbent product according to any one of paragraphs 1-3, in which the core-wrapping sheet is a special paper, and this special paper contains bleached softwood sulphate pulp having a degree of grinding from 400 to 550 ml, as the main material, contains additives of paper-reinforcing substances of two or more types, has a surface density of 10 to 14.5 g / m ² , a density of 0.05 to 0.2 g / cm ³ and a creping degree of 5 to 30%.

5. The absorbent product according to paragraph 4, in which the special paper contains bleached softwood sulphate pulp (NBKP), having a degree of grinding from 400 to 550 ml, as an obligatory component.

6. The absorbent product according to paragraph 4 or 5, in which the roughness of the NBKP fibers used for special paper is 0.1 mg / m or more, and preferably 0.12 mg / m or more, and 0.2 mg / m or less and preferably 0.18 mg / m or less.

7. An absorbent product according to any one of paragraphs 4-6, in which the average length of the NBKP fibers used for special paper is 1 mm or more and preferably 2 mm or more and is 4 mm or less and preferably 3 mm or less.

8. An absorbent product according to any one of paragraphs 4-7, wherein the paper hardening agent added to the special paper is one or more substances selected from the group consisting of carboxymethyl cellulose (CMC) and the corresponding salt, a polyacrylamide-based polymer and the corresponding salt, cationized starch and polyvinyl alcohol (PVA).

9. The absorbent article of claim 8, wherein the combination of paper hardening agents added to the special paper is two types of dry paper hardener and one type of wet paper hardener.

10. An absorbent product according to any one of paragraphs 4-9, in which the total amount of added paper reinforcing substances of two or more types in special paper is 0.01 mass. % or more and preferably 0.03 mass. % or more, and 1.5 mass. % or less, preferably 1.2 mass. % or less with respect to the dry weight of the entire fiber constituting the special paper.

11. An absorbent product according to any one of paragraphs 4-10, in which the surface density of the special paper is 10 g / m ² or more, preferably 11 g / m ² or more, and 14.5 g / m ² or less.

12. An absorbent product according to any one of paragraphs 4-11, in which the density of the special paper is 0.05 g / cm ³ or more, preferably 0.1 g / cm ³ or more, and 0.2 g / cm ³ or less.

13. An absorbent product according to any one of paragraphs 4-12, in which special paper includes creping (creases in the form of fine roughness), and its creping degree is from 5 to 30%.

14. An absorbent product according to claim 2, in which an SMS non-woven fabric (non-woven fabric in which a spunbond nonwoven web, an aerodynamic nonwoven web and a spunbond nonwoven web are laminated and bonded in this order) is a spunbond non-woven web forming at least one surface non-woven fabric, is a special hydrophilic non-woven fabric.

15. The absorbent product according to paragraph 14, in which the surface density of the nonwoven fabric SMS is 5 g / m ² or more, preferably 8 g / m ² or more, and 30 g / m ² or less, preferably 20 g / m ² or less .

16. The absorbent article according to any one of paragraphs 1-15, wherein the absorbent core includes a high density part having a relatively high content of absorbent material and a low density part having a relatively low content of absorbent material, the high density part and the low density part being alternately in a predetermined direction.

17. An absorbent article according to any one of claims 1-16, wherein the absorbent core comprises natural cellulose fiber, which is wood pulp, and / or a hydrophilic synthetic fiber (hereinafter referred to as the “fibrous material”) and an absorbent polymer as the absorbent material.

18. The absorbent product according to paragraph 16 or 17, in which the high-density part and the low-density part are arranged alternately in each direction, including the longitudinal direction and the width direction of the absorbent core,

in particular, in the absorbent core, the low-density portion includes a plurality of linear low-density portions extending along the entire length in the longitudinal direction of the absorbent core, and a plurality of linear low-density portions extending along the entire length in the width direction of the absorbent core, and

low-density parts are generally made in the form of a lattice.

19. An absorbent article according to any one of paragraphs 16-18, in which the low-density part is located in the direction of the thickness of the absorbent core in a sectional view of the absorbent core,

in particular, the low-density part is located on the side of the surface facing the skin in the direction of the thickness of the absorbent core, the surface facing the skin is flat and there are practically no bumps, and there are bumps on the surface of the absorbent core that is not facing the skin, since the high-density part (convexity) has protruding form, and

the low-density part (non-convex part or recess) is located between two high-density parts.

20. The absorbent product according to any one of paragraphs 16-19, in which the ratio (S42 / S41) of the mass (S42) of the low-density part and the mass (S41) of the high-density part of the absorbent core is 20% or more, preferably 30% or more, and 80% or less, preferably 70% or less.

21. The absorbent product according to any one of paragraphs 16-20, in which the surface density of the high-density part is 300 g / m ² or more, preferably 350 g / m ² or more, and 900 g / m ² or less, preferably 800 g / m ² or less.

22. The absorbent product according to any one of paragraphs 1-21, in which the surface density of the fibrous material in the intermediate layer is from half to three times the surface density of the fibrous material in the absorbent core.

23. An absorbent product according to any one of paragraphs 1-22, in which the intermediate layer contains a crosslinked cellulosic fiber made by crosslinking within the cellulose molecules or between the cellulose molecules using a crosslinking agent.

24. The absorbent product according to paragraph 23, in which crosslinking is carried out inside the molecules and between the cellulose molecules in a crosslinked cellulose fiber.

25. The absorbent product according to paragraph 23 or 24, in which the crosslinked cellulose fiber is a mercerized crosslinked cellulose made by crosslinking mercerized cellulose, in which the roundness of the fibers is 0.5 or more.

26. An absorbent product according to any one of paragraphs 22-25, in which the surface density of the fibrous material (total fibrous material containing crosslinked cellulosic fiber) in the intermediate layer is from half to three times, and preferably from single to 2.5 times the surface density of the fibrous material in an absorbent core.

27. An absorbent product according to any one of paragraphs 22-26, in which the surface density of the fibrous material (total fibrous material containing crosslinked cellulose fiber) in the intermediate layer is 50 g / m ² or more, preferably 100 g / m ² or more, and 300 g / m ² or less, preferably 250 g / m ² or less.

28. An absorbent product according to any one of paragraphs 1-27, in which the intermediate layer covers from 20 to 80% and preferably from 30 to 60% of the surface facing the skin (surface on the upper side of the sheet) of the absorbent element.

29. An absorbent article according to any one of paragraphs 1-28, wherein the liquid-permeable backing sheet is located between the top sheet and the intermediate layer.

30. An absorbent article according to claim 29, wherein the liquid-permeable backing sheet is a sheet containing paper or non-woven fabric and occupies a position covering almost the entire area of the intermediate layer.

31. The absorbent product according to paragraph 30, wherein the liquid-permeable backing sheet is selected from the group consisting of wet-made paper, carded non-woven fabric, breathable non-woven fabric, polymer bonded non-woven fabric, spunbond non-woven fabric, aerodynamic non-woven fabric , hydro-woven non-woven fabric and needle-punched non-woven fabric.

32. An absorbent product according to any one of paragraphs 29-31, wherein the surface density of the liquid-permeable backing sheet is 20 g / m ² or more, preferably 30 g / m ² or more, and 70 g / m ² or less, preferably 50 g / m ² or less.

33. An absorbent article according to any one of paragraphs 1-32, in which the top sheet includes numerous bulges protruding to the skin of the user, and numerous recesses adjacent to the bulges.

34. An absorbent product according to any one of paragraphs 1-33, in which petroleum jelly is applied to the top sheet.

35. The absorbent product according to paragraph 34, in which the amount of vaseline deposited on the top sheet, calculated on a solid, is 5 g / m ² or more, preferably 10 g / m ² or more, and 30 g / m ² or less, preferably 20 g / m ² or less.

36. An absorbent product according to any one of paragraphs 1-35, wherein the bottom sheet is a polymer film that is moisture resistant, a polymer film having micropores and having moisture permeability, a water-repellent non-woven fabric, or a lamination product of one sheet and another sheet.

37. An absorbent article according to any one of paragraphs 1-36, wherein the absorbent article is an experimental disposable diaper comprising a rear portion located on the rear side of the user when the user wears the diaper, a front portion located on the front side of the user when the user wears the diaper and the crotch portion located on the crotch of the user when the user wears a diaper.

38. The absorbent product according to paragraph 37, in which a side sheet including a side edge to which the elastic element is attached, is stretched in each of both side parts in the longitudinal direction of the experimental disposable diaper, and a pair of three-dimensional assemblies and a pair of leg assemblies are formed .

Examples

The following are examples of true utility models. However, the present utility model is not limited to these examples.

Wrapping Sheet A-1

NBKP [NBKP was made by mixing two types of cellulose (NBKP), including cellulose under the trade name Cariboo (North American product manufactured by Cariboo Pulp and Paper Company), and cellulose under the trade name ARAUCO (South American product manufactured by ARAUCO), such so that the ratio of the mass content of cellulose of these two types was 5/5] was dispersed in water to produce a uniform suspension in which the fiber concentration was 2 mass. %, and this suspension was loaded into a grinding machine to obtain NBKP, in which the degree of grinding is 500 ml. In addition, during the dilution of the suspension, PAE (trade name WS 4030, manufacturer SEIKO PMC CORPORATION) was added in an amount of 0.78 masses as a wet paper hardener. % relative to the dry weight of the total fiber in suspension. After that, the sodium salt of CMC (trade name Serogen WS-C, manufactured by DAI-ICHI KOGYO SEIYAKU CO., LTD.) Was added in an amount of 0.2 wt. % relative to the dry weight of the entire fiber in the suspension, and sufficiently stirred so that each component was distributed evenly, and a suspension was obtained in which the solids content was 0.1 mass. % The resulting suspension was poured onto a wire mesh for making paper having holes with a diameter of 90 μm (166 mesh), a paper layer was obtained on a wire mesh for making paper, and the paper layer was dehydrated using a suction chamber at a speed of 6 ml / (cm ² · s), and then the paper layer was dried using a dryer. In the process of peeling the paper layer from the dried surface with a doctor blade, creping was performed due to the ratio of winding speeds using a dryer. Thin paper made in this way (crepe paper) was used as the core wrapping sheet A-1.

Wrapping Sheet A-2

Special paper was made according to the procedure described below, and special paper was used as the core wrapping sheet A-2. NBKP (a North American product manufactured under the trade name Cariboo by Cariboo Pulp and Paper Company and having a fiber roughness of 0.15 mg / m and an average fiber length of 2.44 mm) was dispersed in water to form a uniform suspension in which the fiber concentration was 2 mass %, and this suspension was loaded into a grinding machine to obtain NBKP, in which the degree of grinding is 500 ml. In addition, during the dilution of the suspension, PAE (trade name WS 4030, manufacturer SEIKO PMC CORPORATION) was added in an amount of 0.78 masses as a wet paper hardener. % relative to the dry weight of the total fiber in suspension. After that, the sodium salt of CMC (trade name Serogen WS-C, manufactured by DAI-ICHI KOGYO SEIYAKU CO., LTD.) Was added in an amount of 0.2 wt. % relative to the dry weight of the entire fiber in the suspension, and sufficiently stirred so that each component was distributed evenly, and a suspension was obtained in which the solids content was 0.1 mass. % The resulting suspension was poured onto a wire mesh for making paper having holes with a diameter of 90 μm (166 mesh), a paper layer was obtained on a wire mesh for making paper, and the paper layer was dehydrated using a suction chamber at a speed of 6 ml / (cm ² · s), and then the paper layer was dried using a dryer. In the process of peeling the paper layer from the dried surface with a doctor blade, creping was performed due to the ratio of winding speeds using a dryer. Special paper made in this way, with a surface density of 13.5 g / m ² , was used as the core wrapping sheet A-2.

Wrapping Sheet B

An SMS non-woven fabric with a surface density of 13 g / m ² was used as the core wrapping sheet B. The SMS non-woven fabric (core wrapping sheet B) corresponds to type A, and each of the spun non-woven webs forming both surfaces of the SMS non-woven fabric was It is a special hydrophilic non-woven fabric containing synthetic fiber mixed with a hydrophilizing substance.

Wrapping Sheet C

An SMS nonwoven fabric with a surface density of 13 g / m ² was used as the core wrap sheet C. The SMS nonwoven fabric (core wrap sheet C) was type B, and only the spunbond nonwoven fabric forming the surface of the SMS nonwoven fabric was a special hydrophilic non-woven fabric containing synthetic fiber mixed with a hydrophilizing substance. Thereafter, the core wrapping sheet C was classified according to the form of use. In particular, a sheet in which a surface containing a synthetic fiber mixed with a hydrophilizing substance (a special hydrophilic non-woven fabric) is used as a surface facing the skin (upper side), is a core-wrap sheet C-1, and a sheet in which the surface the synthetic fiber mixed with a hydrophilizing substance (a special hydrophilic non-woven fabric) is used as the surface that is not turned to the skin (bottom side) as a core-wrapping sheet C-2.

Wrapping Sheet D

The sheet which was hydrophilic by applying a hydrophilizing agent to the surface of the fiber constituting the SMS nonwoven fabric, whose surface density was 10 g / m ² , intended for use in a commercially available disposable diaper, was a core wrapping sheet D.

The liquid penetration time was measured five times, implementing the measurement method described above with respect to the core-wrapping sheets A-D.

Table 1 Type of Liquid Penetration Time (seconds) First Second Third Fourth Fifth Wrapping Sheet A-1 Wrapping Sheet 38 40 40 41 41 A-2 Special paper 37 39 38 37 37 AT SMS non-woven fabric (contains mixed hydrophilizing substance) (both surfaces are special hydrophilic non-woven fabrics) 40 41 43 43 45 S-1 SMS non-woven fabric (contains mixed hydrophilizing substance) [only surface A (surface facing the skin) is a special hydrophilic non-woven fabric] 42 41 45 56 56

S-2 SMS non-woven fabric (contains mixed hydrophilizing substance) [only surface A (non-skin surface) is a special hydrophilic non-woven fabric] 48 52 57 62 81 D SMS non-woven fabric (contains applied hydrophilizing agent) 35 42 70 111 296

Example 1

An experimental disposable diaper (product corresponding to size M) was made, the basic configuration of which was similar to the configuration of diaper 1 illustrated in FIG. 1 and 2, and it was determined as the sample of Example 1. A sheet that contained a commercially available disposable diaper (trade name Pampers Cotton Care Tape, manufactured by Procter & Gamble) was used as each sheet, including a top sheet, a liquid permeable backing sheet and an intermediate layer. As for the intermediate layer, the ratio of the crosslinked cellulosic fiber to the total fiber constituting the intermediate layer was 100 mass. % In addition, the surface density of the fibrous material in the intermediate layer was approximately 180 g / m ² , which corresponded to a 0.9-fold surface density of the fibrous material in the absorbent core, which is described below. Weak permeable to liquids and moisture permeable polyethylene polymer film (containing calcium carbonate), in which the surface density was 25 g / m ² was used as the bottom sheet. The flat absorbent core, in which there were practically no irregularities, was used as an absorbent core, which contained a finely divided superabsorbent polymer (SAP) in the fiber structure, and this core was a homogeneous mixture of 200 g / m ² fluff pulp and 286 g / m ² absorbent polymer, and its total surface density was 486 g / m ² . The total length of the absorbent core in the longitudinal direction was 370 mm, the total length (maximum length) of the absorbent core in the width direction was 120 mm, and the shape of the absorbent core in the plan view was an hourglass shape, as illustrated in FIG. 1. A core-wrapping sheet A-1 was used as a core-wrapping sheet.

Example 2

An experimental disposable diaper was made by a method similar to Example 1, except that the core-wrapping sheet A-2 was used instead of the core-wrapping sheet A-1, and it was a sample of example 2.

Example 3

An experimental disposable diaper was made in a manner analogous to Example 1, except that the core wrapping sheet B was used instead of the core wrapping sheet A-1, and it was a sample of Example 3.

Example 4

An experimental disposable diaper was made by a method similar to Example 1, except that the core-wrap sheet C-1 was used instead of the core-wrap sheet A-1, and it was a sample of example 4. Thus, in example 4, the core-wrap sheet C was located in the diaper so that the spunbond nonwoven fabric, which is a special hydrophilic nonwoven fabric, forms a surface facing the skin (surface facing the intermediate layer) of the wrapping the core of sheet C.

Example 5

An experimental disposable diaper was made in a manner analogous to Example 1, except that the core-wrap sheet C-2 was used instead of the core-wrap sheet A-1, and it was a sample of Example 5. Thus, in example 5, the core-wrap sheet C was located in the diaper so that the spunbond nonwoven fabric, which is a special hydrophilic nonwoven fabric, forms a surface that is not turned to the skin (the surface that is not turned to the intermediate layer) I wrap core of sheet C.

Example 6

An experimental disposable diaper was made in a manner analogous to Example 1, except that the uneven absorbent core having a configuration approximately similar to that of the absorbent core 40A, which is illustrated in FIG. 6 was used as the core-wrapping sheet, and it was a sample of Example 6. The uneven absorbent core used in Example 6 contained a finely dispersed absorbent polymer in the fiber structure, its total length in the longitudinal direction was 370 mm, and the total length (maximum length) in the width direction was 120 mm, and it had an hourglass shape as a shape in a plan view. The block size of the uneven high-density part was 10 × 20 mm, and the width of the recess of the low-density part was 2 mm. In addition, in the uneven absorbent core used in example 6, the high-density part has a total surface density of 466 g / m ² on average for a homogeneous mixture, including an average of 223 g / m ^{2 of} fluff pulp and an average of 243 g / m ² absorbent polymer and low-density portion had a total areal density averaging 257 g / m ² for the homogeneous mixture, including an average 152 g / m ² fluff pulp and an average of 105 g / m ² of the absorbent polymer, the ratio of surface density fluff cellulite s high density parts and low density parts (high-density portion / low-density portion) was 1.5, and the ratio of surface density of the absorbent polymer (high-density portion / low-density portion) was 2.3.

Comparative Example 1

An experimental disposable diaper was made by a method analogous to Example 1, except that the core-wrapping sheet D was used instead of the core-wrapping sheet A, and it was a sample of comparative example 1.

Reference Example 2

An experimental disposable diaper was made by a method analogous to comparative example 1, except that fluff pulp, which had a surface density of 180 g / m ² , was used as an intermediate layer, and it was a sample of comparative example 2. The intermediate layer (cellulose) for use in comparative example 2 does not contain cross-linked cellulose fiber, but contains cellulose fiber (100% NBKP) as a component fiber.

Rating

For each sample (disposable diaper) in the examples and comparative examples, each parameter, such as the liquid absorption time at constant pressure, the liquid diffusion area in the absorbent core, the amount of residual liquid in the intermediate layer, and the amount of liquid return in the absence of pressure, were measured as described below measurement method. In addition, with regard to the core wrapping sheet in each sample, the wet strength was measured by the measurement method described. The results are presented below in table 2.

The method of measuring the area of liquid diffusion in the absorbent core, the amount of residual liquid in the intermediate layer of the liquid return value in the absence of pressure

The disposable diaper was flattened, giving it a flat shape, 40 g of absorbable artificial urine was released at a discharge rate of 5 g / s onto the top sheet in the central part of the absorbent element in a state of no pressure, in which the top sheet was turned upward; a disposable diaper was attached to a horizontal plane and held for 10 minutes. After that, 40 g of absorbable artificial urine was released at the same rate of release. The release of artificial urine was repeated three times, and in total, the diaper absorbed 120 g of artificial urine. After that, four collagen films (trade name COFFI, manufacturer Naturin Corporation), having the shape of a square, whose sides were 70 mm, were placed on the absorbent artificial urine part of the diaper, the collagen films were kept under load for one minute, and artificial urine absorbed in diaper absorbed in collagen films. Collagen films had the same contact angle as human skin. A weight of 4 kg (pressure on the diaper was approximately 7 kPa from a minimum of 2 kPa to a maximum of 21 kPa during wetting after the liquid was discharged) was mounted on an acrylic plate having a square shape and dimensions of 70 mm × 70 mm, in the central part of which there was a round convexity having a diameter of 20 mm and a height of 5 mm. After one minute, the load was removed, and the mass (g) of collagen films with absorbed artificial urine was measured. The mass of collagen films before absorbing artificial urine was subtracted from the mass of collagen films with absorbed artificial urine, and the resulting difference was determined as the amount of liquid return (g) in the absence of pressure. In addition, the intermediate layer and the liquid-permeable backing sheet were removed from the diaper after measuring the liquid return after absorbing artificial urine, the mass (g) of the intermediate layer and the liquid-permeable backing sheet was measured, and the “liquid return value (g) was summed with the measured mass at no pressure ”, and the resulting amount was determined as the amount of residual liquid in the intermediate layer. A small amount of residual liquid in the intermediate layer and a small amount of liquid return in the absence of pressure are highly appreciated. In addition, the diaper after measuring the return of liquid after absorption of artificial urine was examined from the upper side of the sheet, the diffusion area of artificial urine in the part of the absorbent core was measured, and the measured value was determined as the area of liquid diffusion in the absorbent core (cm ² ). When the area of liquid diffusion in the absorbent core is large, it is determined that the liquid diffusion property is excellent, and a high rating is given. In this case, the same artificial urine was used as artificial urine, as in the method for measuring the time of liquid penetration.

table 2 Examples Comparative examples one 2 3 four 5 6 one 2 Intermediate fiber component fiber Crosslinked Cellulose Fiber Crosslinked Cellulose Fiber Crosslinked Cellulose Fiber Crosslinked Cellulose Fiber Crosslinked Cellulose Fiber Crosslinked Cellulose Fiber Crosslinked Cellulose Fiber Cellulose fiber Wrapping Sheet Type of A-1 A-2 AT S-1 S-2 A-1 D D Wet Strength (N) 0.4 0.3 10.5 11.0 11.0 0.4 9.2 9.2 Liquid penetration time a third time (seconds) 40 38 43 45 57 40 70 70 Absorbent core Flat type Flat type Flat type Flat type Flat type Flat type Flat type Flat type

Absorption properties The amount of fluid return (g) 0,043 0,043 0.051 0,050 0,050 0,038 0,061 0.114 The amount of fluid return of the intermediate layer (g) 5.3 4.6 5,0 6.3 6.6 8.0 7.8 13.8 The diffusion area of the liquid in the absorbent core (cm ² ) 212 213 206 202 202 236 185 151

Table 2 clearly shows that the diaper in each example shows a small amount of liquid return in the absence of pressure in comparison with the diaper in each comparative example. As a result, the diaper was not sticky in each example, although the diaper was sticky in each comparative example when the diaper was touched after absorbing artificial urine. In addition, since the diaper in each example contained a small amount of residual liquid in the intermediate layer, it was obvious that moisture from the intermediate layer rarely evaporated towards the skin. In addition, since the area of liquid diffusion in the absorbent core is large, the property of liquid diffusion in the absorbent core is excellent, and the absorbent core can be effectively used. Thus, it is obvious that the mass of liquid that is present in this place is reduced, and the effect on the skin can be reduced. In addition, when an uneven absorbent core is used (Example 6), the amount of liquid return in the absence of pressure is small, and the area of liquid diffusion in the absorbent core is large compared to the case in which a flat absorbent core is used (Example 1). Thus, the effectiveness of using an uneven absorbent core to prevent fluid return, as well as the efficiency of using an absorbent core, becomes apparent.

On the other hand, the diaper in each comparative example has a large amount of liquid return, at least in the absence of pressure, mainly because the third time the liquid penetration time of the core-wrapping sheet exceeds 60 seconds compared to the diaper in each example, in which time liquid penetration is 60 seconds or less. In addition, the result is a small area of liquid diffusion in the absorbent core. The core wrapping sheet D used in each comparative example was initially obtained by applying a hydrophilizing agent to the surface of a fiber constituting a water-repellent non-woven fabric to give it hydrophilicity. Thus, in the case of a core-wrap sheet containing the hydrophilizing substance, the hydrophilicity of the core-wrap sheet decreases (hydrophobicity increases) and the permeability to liquids decreases due to the repeated release / absorption of the biological fluid, such as urine, during use of the absorbent article. In addition, the diaper of comparative example 2 has a large amount of liquid and residual liquid return in the intermediate layer, since the constituent fiber of the intermediate layer is 100% cellulose fiber, in comparison with each example and comparative example 1, in which the constituent fiber of the intermediate layer is 100 % is a crosslinked cellulosic fiber.

From the above it becomes obvious that the conditions (1) the intermediate layer contains a crosslinked cellulose fiber, and (2) the first, second and third times the liquid penetration time is 60 seconds or less when measuring the liquid penetration time three or more times by the specified measurement method with respect to the core-wrapping sheet, are important for obtaining an absorbent article that exhibits excellent liquid permeability, contains a small amount of residual liquid and rarely causes return fluid. In addition, it is obvious that paper (special paper) containing a hydrophilic fiber, such as cellulose, and a non-woven fabric (special hydrophilic non-woven fabric) containing a synthetic fiber mixed with a hydrophilizing substance, comprising a synthetic polymer in which the hydrophilizing substance is premixed, such as fibrous starting material are suitable for a core wrapping sheet satisfying condition (2).

Claims (37)

1. An absorbent article comprising a liquid-permeable topsheet on the skin side of the surface, a liquid-impermeable topsheet on the non-skinned side of the surface, and an absorbent member located between these sheets and including an intermediate layer located between the topsheet and the absorbent member moreover, the top sheet includes numerous bulges protruding towards the skin of the user, and numerous recesses adjacent to the bulges, the intermediate layer contains A crosslinked cellulose fiber, the absorbent element includes an absorbent core containing absorbent material, and a core wrapping sheet covering at least the skin-facing surface of the absorbent core, and containing paper or a hydrophilic non-woven fabric, and the liquid penetration time into the first, second and the third time is 60 seconds or less when re-measuring the liquid penetration time three or more times by the measurement method with respect to the core wrapping sheet. 2. The absorbent product according to claim 1, in which the core-wrapping sheet includes a nonwoven fabric obtained by a spinneret - aerodynamic - spinneret method, and a spunbond nonwoven web that forms at least one surface of the nonwoven web contains a synthetic fiber mixed with a hydrophilizing substance, using a synthetic polymer in which the hydrophilizing agent is premixed as a fibrous starting material. 3. The absorbent article of claim 1, wherein the core-wrapping sheet has a width of not less than two and not more than three times in the width direction of the absorbent core, and the entire area of each surface, including the surface of the absorbent core facing the skin and not facing skin on the surface of its opposite side, covers one part of the sheet wrapping the core. 4. The absorbent product according to claim 1, wherein the core wrapping sheet is a special paper, said special paper containing bleached softwood sulphate pulp having a grinding degree of 400 to 550 ml, as the main material, contains additives of paper-reinforcing substances of two or more types has a surface density of 10 to 14.5 g / m ² , a density of 0.05 to 0.2 g / cm ³ and a creping degree of 5 to 30%. 5. An absorbent product according to claim 4, in which the special paper contains bleached softwood sulphate pulp (NBKP) having a degree of grinding from 400 to 550 ml, as an obligatory component. 6. An absorbent product according to claim 4, wherein the fiber roughness of bleached softwood sulphate pulp used for special paper is 0.1 mg / m or more and 0.2 mg / m or less. 7. The absorbent article of claim 4, wherein the average length of the NBKP fibers used for special paper is 1 mm or more and 4 mm or less. 8. The absorbent article of claim 4, wherein the paper hardening agent added to the special paper is one or more substances selected from the group consisting of carboxymethyl cellulose and the corresponding salt, a polyacrylamide-based polymer and the corresponding salt, cationized starch and polyvinyl alcohol. 9. The absorbent article of claim 8, wherein the combination of paper hardening agents added to the special paper is two types of dry paper hardener and one type of wet paper hardener. 10. An absorbent product according to claim 4, in which the total amount of added paper reinforcing substances of two or more types in special paper is 0.01 wt.% Or more and 1.5 wt.% Or less with respect to the dry weight of the entire fiber, making up special paper. 11. An absorbent product according to claim 4, in which the surface density of special paper is 10 g / m ² or more and 14.5 g / m ² or less. 12. An absorbent product according to claim 4, in which the density of special paper is 0.05 g / cm ³ or more and 0.2 g / cm ³ or less. 13. The absorbent product according to claim 4, in which special paper includes creping, and its degree of creping is from 5 to 30%. 14. The absorbent product according to claim 2, in which, in the SMS nonwoven fabric, the spunbond nonwoven fabric that forms at least one surface of the nonwoven fabric is a special hydrophilic nonwoven fabric, and the special hydrophilic nonwoven fabric contains a synthetic mixed with a hydrophilizing substance a fiber in which a synthetic polymer pre-mixed with a hydrophilizing substance is used as a fibrous starting material. 15. The absorbent product according to claim 14, in which the surface density of the nonwoven fabric SMS is 5 g / m ² or more and 30 g / m ² or less. 16. The absorbent product according to claim 1, in which the absorbent core includes a part with a high surface density having a relatively high content of absorbent material, and a part with a low surface density having a relatively low content of absorbent material, the high-density part and the low-density part are located alternately in given direction. 17. The absorbent article of claim 1, wherein the absorbent core comprises natural cellulose fiber, which is wood pulp, and / or a hydrophilic synthetic fiber and an absorbent polymer, as an absorbent material. 18. The absorbent article of claim 16, wherein the high-density part and the low-density part are arranged alternately in each of the longitudinal direction and the width direction of the absorbent core, while the low-density part in the absorbent core includes a plurality of linear parts with low surface density extending over the entire length of a longitudinal direction of the absorbent core, and a plurality of linear parts with low surface density extending along the entire length in the width direction of the absorbent core, and low The parts are generally in the form of a grill. 19. The absorbent product according to claim 16, in which the low-density part is located in the thickness direction of the absorbent core in a sectional view of the absorbent core, the low-density part is located on the side of the surface facing the skin in the thickness direction of the absorbent core, the surface facing the skin is flat, and bumps are essentially absent, and bumps are present on the surface of the absorbent core that is not turned to the skin, since the high-density part has a protruding shape and the low-density part It located between the two high-density parts. 20. The absorbent product according to claim 16, in which the ratio of the mass of the low-density part and the mass of the high-density part of the absorbent core is 20% or more and 80% or less. 21. The absorbent product according to claim 16, in which the surface density of the high-density part is 300 g / m ² or more and 900 g / m ² or less. 22. The absorbent product according to claim 1, in which the surface density of the fibrous material in the intermediate layer is from 0.5 to 3 from the value of the surface density of the fibrous material in the absorbent core. 23. The absorbent article of claim 1, wherein the intermediate layer comprises a crosslinked cellulosic fiber made by crosslinking within the cellulose molecules or between the cellulose molecules using a crosslinking agent. 24. An absorbent product according to claim 23, in which crosslinking is carried out inside the molecules and between the cellulose molecules in a crosslinked cellulose fiber. 25. An absorbent product according to claim 23, in which the crosslinked cellulose fiber is a mercerized crosslinked cellulose made by crosslinking mercerized cellulose, in which the roundness of the fibers is 0.5 or more. 26. An absorbent product according to claim 22, in which the surface density of the fibrous material in the intermediate layer is from 0.5 to 3 of the magnitude of the surface density of the fibrous material in the absorbent core. 27. An absorbent product according to claim 22, in which the surface density of the fibrous material in the intermediate layer is 50 g / m ² or more and 300 g / m ² or less. 28. An absorbent product according to claim 1, in which the intermediate layer covers from 20 to 80% of the surface of the absorbent element facing the skin. 29. An absorbent product according to claim 1, in which a liquid-permeable sublayer is located between the top sheet and the intermediate layer. 30. An absorbent product according to claim 29, in which the liquid-permeable sublayer is a sheet that contains paper or non-woven fabric and is located so as to cover almost the entire area of the intermediate layer. 31. An absorbent product according to claim 30, wherein the liquid-permeable sublayer is selected from the group consisting of wet-made paper, carded non-woven fabric, breathable non-woven fabric, polymer-bonded non-woven fabric, spunbond non-woven fabric, aerodynamic non-woven fabric , hydro-woven non-woven fabric and needle-punched non-woven fabric. 32. An absorbent product according to claim 29, in which the surface density of the liquid-permeable sublayer is 20 g / m ² or more and 70 g / m ² or less. 33. An absorbent product according to claim 1, in which Vaseline is applied to the top sheet. 34. An absorbent product according to claim 33, wherein the amount of petroleum jelly applied to the top sheet, calculated as a solid, is 5 g / m ² or more and 30 g / m ² or less. 35. An absorbent product according to claim 1, in which the bottom sheet is a polymer film that is moisture resistant, a polymer film having micropores and having moisture permeability, a water-repellent non-woven fabric or a lamination product of one sheet and another sheet. 36. The absorbent article of claim 1, wherein the absorbent article is an experimental disposable diaper comprising a rear portion located on the rear side of the user when the user wears the diaper, a front portion located on the front side of the user when the user wears the diaper, and crotch the part located on the crotch of the user when the user wears a diaper. 37. An absorbent product according to claim 36, in which a lateral sheet including a lateral edge to which an elastic element is attached is in a stretched state located in each of both lateral parts in the longitudinal direction of the experimental disposable diaper, and a pair of three-dimensional assemblies and a pair of assemblies are formed for legs.

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