TW201812131A - Spunbonded non-woven fabric, sheet, and absorbent article - Google Patents

Abstract

Spunbonded non-woven fabric is made from fiber of a thermoplastic resin and has a predetermined water resistance which has, when the anti-water pressure thereof is measured in a conformity with ISO811, a second anti-water pressure measured for the second time or subsequent to the second time degrading by a predetermined pressure or lower from the first anti-water pressure measured for the first time. The first anti-water pressure is equal to or more than 160 mmH2O and the predetermined pressure is equal to or less than 30 mmH2O.

Description

   Spunbond nonwovens, sheets and absorbent articles   

This case relates to absorbent articles such as paper diapers, sanitary napkins, the preferred sheets used therefor, and the preferred spunbond nonwovens used therefor.

Conventional absorbent articles are provided with absorbent pads that absorb liquids such as urine and menstrual blood excreted by the wearer, as well as water-resistant sheets that can withstand a predetermined water pressure. By designing the three-dimensional pleats and the outer edge of the sheet, the sheet can suppress the leakage of the absorbent article.

One of the water-resistant sheets is a meltblown nonwoven fabric. Although the meltblown non-woven fabric has small openings, it is difficult for water to penetrate, but the strength is low. On the other hand, the spun-bonded nonwoven fabric, which is one of the other nonwoven fabrics, has larger openings than the meltblown nonwoven fabric, so that moisture can easily penetrate, but the strength is higher.

Therefore, a water-resistant sheet that uses a spunbond nonwoven fabric to reinforce a meltblown nonwoven fabric has been developed. For example, as shown in FIG. 3A, the melt-blown nonwoven 42 is sandwiched by two layers of spun-bonded nonwoven 41, 41, and as shown in FIG. 3B, the SMS nonwoven of the melt-blown nonwoven 42 is reinforced by the spun-bonded nonwoven 41, 41. 40. The use of a water-resistant sheet is investigated (see Patent Document 1).

    [Prior technical literature]         [Patent Literature]    

[Patent Document 1] Japanese Patent Laid-Open No. 2015-66308

However, if the melt-blown nonwoven fabric layer of the SMS nonwoven fabric is damaged, the water pressure resistance of the sheet will be greatly reduced in accordance with the opening of the spun-bonded nonwoven fabric layer. Therefore, if a high water pressure is repeatedly applied to a water-resistant sheet using an SMS nonwoven fabric in an absorbent article, there is a possibility that the liquid leakage may not be suppressed. Therefore, there is still room for improvement in terms of ensuring wearer comfort.

The absorbent article of the present case, the preferred sheet used therefor, and the preferred spunbonded nonwoven fabric used therefor were completed in view of the above-mentioned problems, and one of the objects is to ensure the comfort of the wearer.

In addition, it is not limited to the so-called purpose here, and the actions and effects derived from the components shown in the "embodiment" described later, and the actions and effects that cannot be obtained by the conventional technology can be attributed to other purposes of the present case.

The inventors of the present case have intensively studied to solve the above problems, and the result is not from the conventional viewpoint of making the meltblown nonwoven fabric used in the sheet water-resistant, but from a new viewpoint of making the spunbonded nonwoven fabric used in the sheet have a predetermined water resistance. On departure, an absorbent article was found to ensure the comfort of the wearer.

(1) The spun-bonded nonwoven fabric disclosed herein uses fibers of a thermoplastic resin. The spunbonded nonwoven has a predetermined water resistance when the water resistance is repeatedly measured in accordance with ISO811, and the second water resistance measured after the second time is lower than the first water resistance measured in the first time. Sex. The first water pressure resistance is 160 mmH ₂ O or more, and the predetermined pressure is 30 mmH ₂ O or less. In addition, the said predetermined water resistance means the physical property which continues to satisfy the water pressure resistance required for this sheet | seat.

(2) The average fineness of the fibers is preferably 0.1 to 1.0 denier, and the basis weight of the spunbonded nonwoven fabric is preferably 8 to 20 g / m ² .

(3) The thermoplastic resin is preferably a polyolefin resin containing polypropylene.

(4) The above polyolefin resin preferably satisfies the following <characteristic a> to <characteristic h>: <characteristic a> the meso pentad component ratio is 30 to 80 mol%; <characteristic b> combines the above When the racemic pentad component ratio is set to "A" and the racemic pentad component ratio is set to "B", the inequality I "B / (1-A) ≦ 0.1" is satisfied; <characteristic c> racemic Meso racemic meso five-unit composition ratio is greater than 2.5 mole%; <characteristic d> set meso three-unit composition ratio to "C" and racemic three-unit composition ratio to " When D ”and the triad component ratio are set to“ E ”, the inequality II“ C × D / E ² ≦ 2.0 ”is satisfied; <Characteristic e> The weight average molecular weight is 10,000 to 200000; When “Mw” is set and the number average molecular weight is “Mn”, the inequality III “Mw / Mn ≦ 4” is satisfied; <characteristic g> The amount of the extract using boiling diethyl ether is 0 to 10% by mass; > The low-crystalline polyolefin resin satisfying the above-mentioned <characteristic a> to <characteristic g> is based on the total solid content of 5 to 50% by mass.

(5) The sheet disclosed herein preferably contains the above-mentioned spunbonded nonwoven fabric, but does not include a meltblown nonwoven fabric. That is, it is preferable that this sheet | seat consists only of the said spun-bonded nonwoven fabric.

(6) The sheet is preferably such that the area ratio of the embossed portion where the fibers are fused to each other is 5 to 25%.

(7) The sheet is preferably overlapped by two or more sheets.

(8) Furthermore, it is preferable that the absorbent article disclosed here is that the above-mentioned sheet is arranged on the side of the body.

(9) Moreover, it is preferable that the said absorbent article is the said sheet material used for the three-dimensional pleats which were erected on the said side.

According to the absorbent article of the present case, by making the spin-bonded nonwoven fabric used for the sheet to have a predetermined water resistance, it is possible to suppress the liquid discharged from the wearer from penetrating the sheet, and it is possible to suppress liquid leakage. Therefore, the comfort of the wearer can be ensured.

1‧‧‧ 胯 Lower

2‧‧‧ pattern

10‧‧‧ Absorber

11‧‧‧ package

12‧‧‧ Absorbent pad

13‧‧‧top flakes

14‧‧‧Back sheet

15‧‧‧ Overlay

15c‧‧‧Outside Sheet Department

20‧‧‧Side Panel (Sheet)

20a‧‧‧Inner wall sheet department

20b‧‧‧Outer wall sheet department

20c‧‧‧Outside Sheet Department

21‧‧‧ three-dimensional folds

22‧‧‧ Leg Crinkles

31‧‧‧The first silk rubber

32‧‧‧Second Silk Rubber

40‧‧‧SMS Non-woven

41‧‧‧spun bonded non-woven fabric (layer)

42‧‧‧meltblown non-woven fabric (layer)

Fig. 1 is a partial cross-sectional view of a paper diaper (absorbent article) cut and cut at the lower part of the crotch.

Fig. 2 is a schematic perspective view schematically showing a sheet of a spun-bonded nonwoven fabric.

In FIG. 3, FIG. 3A and FIG. 3B are schematic perspective views of the sheet of the SMS nonwoven fabric. The layers of the nonwoven fabric of FIG. 3A are separated from each other, and the layers of the nonwoven fabric are laminated in FIG. 3B.

The absorbent article according to the embodiment will be described with reference to the drawings. In addition, the embodiments shown below are merely examples at best, and are not intended to exclude the application of various changes and technologies not explicitly shown in the following embodiments. Each configuration of the present embodiment can be modified in various ways without departing from the spirit and the like. In addition, they can be selected or combined as needed.

The absorbent article according to this embodiment is a sanitary product which is tried on by a wearer and absorbs liquids such as urine and menstrual blood. Examples of the absorbent article include a tape-type / underpants-type diaper (so-called "disposable diaper"), a diaper, a sanitary napkin, a panty protector, and the like. In the following embodiments, the absorbent article is exemplified by a tape-type diaper.

In this embodiment, the related diaper is a longitudinal direction of the connection direction of the front body located on the wearer's abdomen and the back body located on the back, and the side facing the wearer's skin (the inside of the try-on state) is set to the body-side, The back side (outside of the try-on state) of the close-fitting side is set to a non-fitting-side. In addition, the connection direction between the close-fitting side and the non-fit-fitting side is set to the thickness direction, and the direction orthogonal to the long-side direction and the thickness direction is set to the width direction.

In addition, in this embodiment, the description of "a numerical value X to a numerical value Y" means "a numerical value X or more and a numerical value Y or less" unless otherwise stated.

    [I. An embodiment]         [1. Paper diapers]    

First, the basic structure of a paper diaper is demonstrated with reference to FIG. Here, the configuration of the lower crotch 1 located under the wearer's crotch in the paper diaper will be mainly described.

The lower part 1 of the diaper is located at the center in the longitudinal direction. The lower crotch portion 1 is provided with an absorber 10 on the inner side in the width direction, and a side panel (sheet) 20 on the close-fitting side on the outer side in the width direction.

The absorbent body 10 is a liquid-absorbing element composed of a plurality of sheet-like or pad-like members. In the absorbent body 10, a top sheet (also referred to as a "sandwich sheet") 13 is disposed on the side of the absorbent pad (also referred to as "core") 12 covered (wrapped) by the wrapping sheet 11, and a back portion is disposed on the side that is not closed片 材 14。 Sheet 14. The non-body-contacting side of the absorbent body 10 (that is, the non-body-contacting side of the back sheet 14) is covered with a cover sheet 15.

In order to allow the liquid discharged by the wearer to be absorbed by the absorbent pad 12, the absorbent body 10 has a property (liquid penetrability) that the wrapping sheet 11 and the top sheet 13 penetrate the liquid. On the other hand, in order to prevent the liquid absorbed by the absorbent pad 12 from leaking, the back sheet 14 and the cover sheet 15 are made liquid-impermeable (liquid-impermeable).

In addition, in order to improve the fit of the paper diaper to the wearer, the diffusibility of the liquid excreted on the absorbent body 10, and the breathability of the paper diaper, the grooved pattern 2 is provided in the absorbent body 10.

The side sheet 20 is a sheet-like member provided to prevent the liquid diaper from leaking. Therefore, the side sheet 20 is also liquid-impermeable. This side sheet 20 has predetermined water resistance which will be described in detail later.

Here, in the side sheet 20, folds 21 and 22 are provided in each of the end portions in the width direction and their peripheral edges (hereinafter referred to as "end edge portions") in the longitudinal direction. In the side panel 20, a three-dimensional creasing 21 standing upright toward the body-side is formed at an end edge portion on the inner side in the width direction, and a leg creasing 22 protruding from the width direction outer side is formed on the end edge portion on the outer side in the width direction.

The three-dimensional folds 21 are provided to prevent the discharged liquid from leaking outward in the width direction.

In the three-dimensional pleated 21-type side sheet 20, the sheet portions 20a and 20b located at the end edges on the inner side in the width direction are folded and overlapped, and the first wire extending in the longitudinal direction is surrounded by the sheet portions 20a and 20b. Rubber (elastic member) 31. In other words, the side sheet 20 has the inner wall sheet portion 20 a arranged inside the width direction with respect to the first wire rubber 31, and the outer wall sheet portion 20 b has been arranged outside the width direction with respect to the first wire rubber 31. Therefore, a part of the side sheet 20 is overlapped by the two sheet parts 20a and 20b.

In accordance with this, the first silk rubber 31 is built in the place where the sheet portions 20a and 20b of the side sheet 20 are folded and overlapped, thereby forming a three-dimensional crimp 21 that is erected on the side of the body and is crimped.

The leg gathers 22 are provided to improve the tracking of the wearer's feet and improve comfort.

The leg gathers 22 overlap the outer sheet portion 20c of the end edge portion of the side sheet 20 on the outer side in the width direction and the outer sheet portion 15c of the end edge portion of the cover sheet 15 on the outer side in the width direction. The iso-side sheet portions 20c and 15c surround a second wire rubber (elastic member) 32 extending in the longitudinal direction.

Accordingly, by forming the second silk rubber 32 in the overlapping position of the side sheet 20 and the outer sheet portions 20c and 15c of the cover sheet 15, a crimped leg fold is provided which protrudes outward in the width direction and is crimped. twenty two.

    [2.Side panels]    

Next, a detailed configuration of the side sheet 20 will be described.

The side sheet 20 is composed only of a spun-bonded non-woven fabric using thermoplastic resin fibers. Therefore, for example, a nonwoven fabric containing a meltblown layer (meltblown nonwoven fabric) such as an SMS nonwoven fabric or a SMMS nonwoven fabric, or a meltblown nonwoven fabric composed of only a meltblown layer is not included in the side sheet 20.

The "spun-bonded nonwoven fabric" refers to a sheet-like member obtained by spinning out a continuous fiber from a thermoplastic resin and aggregating it. In this spun-bonded nonwoven fabric, the aggregated spun yarns become long fibers (long fibers), respectively. Here, by applying one or both of heat and / or pressure, the embossing process is performed on the spun-bonded nonwoven fabric by welding the fibers to each other.

Here, the specific manufacturing method of a spun-bonded nonwoven fabric can be illustrated as follows.

First, a long fiber group composed of the spun yarn discharged from the thermoplastic resin in a molten state is introduced into a pneumatic suction cup and extended to defibrate, and then a fiber web can be obtained by being gathered on a conveyor belt. Next, the long fiber groups forming the fiber web are joined to each other by embossing. For example, a pattern of irregularities arranged regularly in the direction of flow of the conveyor belt and its orthogonal direction is provided to the fiber web by an embossing roll formed with irregularities corresponding to the pattern of irregularities on the outer periphery. The embossed fiber web was made into a spunbond nonwoven fabric.

The “meltblown nonwoven fabric” refers to a sheet-like member obtained by aggregating short fibers (short fibers) produced by spraying molten thermoplastic resin in a spray-like manner. This melt-blown nonwoven fabric has a lower strength and smaller openings than a spun-bonded nonwoven fabric.

Hereinafter, the side sheet 20 will be described in detail in the order of the structural constitution and the chemical constitution.

    [2-1. Structural composition]    

As shown in FIG. 2, the side sheet 20 of this embodiment uses fibers having a smaller diameter than those used in conventionally spun-bonded non-woven fabrics (see element symbol 41 in FIG. 3), and is manufactured using high-density openings. Spun bonded non-woven fabrics with smaller pores can suppress the decrease in strength and have a predetermined water resistance. In other words, the water resistance of the side sheet 20 is the responsibility of the spun-bonded nonwoven fabric constituting the side sheet 20. Therefore, the spun-bonded nonwoven fabric has a predetermined water resistance.

Here, the "predetermined water resistance" means that when water pressure is repeatedly applied, the physical properties required for the water pressure resistance of the side panel 20 are continuously satisfied.

Since the spun-bonded nonwoven fabric used for the side sheet 20 can ensure the strength, even if the water pressure is repeatedly applied, the reduction or change in the water pressure resistance is suppressed, and the water pressure resistance is improved because the opening is small. In other words, the side panel 20 made of a spunbond non-woven fabric is stronger than a non-woven fabric containing a meltblown layer, for example, and is not easily broken even when water pressure is applied, and it is easy to maintain a water pressure resistance corresponding to "openings". Therefore, even if water pressure is repeatedly applied, the water pressure resistance is not easily reduced.

The above-mentioned predetermined water resistance naturally refers to the "water pressure resistance" of the spun-bonded nonwoven fabric, and corresponds to the "opening" and "area ratio of the embossed portion (hereinafter referred to as" embossed area ratio ") of the spun-bonded nonwoven fabric.

Here, the spun-bonded nonwoven fabric used for the relevant side sheet 20 will be described with reference to "water pressure resistance", "opening", and "embossed area ratio".

    <Water pressure resistance>    

The so-called "water pressure resistance" refers to the upper limit of the water pressure that can be withstood. Specifically, the upper limit of the water surface height relative to the spunbond nonwoven fabric is "water pressure resistant" when the water contained in the bottomless cylinder provided on the spunbonded nonwoven fabric is not penetrated.

Specifically, when the water pressure resistance is repeatedly measured according to ISO811, the amount of decrease in the second water pressure resistance P ₂ measured after the second time compared to the first water pressure resistance P ₁ measured in the first time is below the predetermined pressure P _P The spun-bonded nonwoven fabric is used for the side panel 20.

To prevent the leakage of excreted fluid, a first pressure P ₁ and the deduction resistance by the water pressure resistance in the first predetermined pressure P _{1 P} P out of a second predetermined pressure P _2, the required pressure of more than necessary. The hydraulic pressure is, for example, 130 mmH ₂ O.

Here, the first water pressure resistance P ₁ is set to 160 mmH ₂ O or more. The first water-pressure resistance P _1, to reliably prevent liquid leakage from the point of view, more preferred based 170mmH ₂ O, more preferably more based 180mmH ₂ O.

The predetermined pressure P _P is set to 30 mmH ₂ O or less. The predetermined pressure _P P, to prevent leakage from the performance point of view is maintained, preferably based 20mmH ₂ O or less, more preferably based 10mmH ₂ O or less.

Therefore, the second water pressure resistance P _{2 is} set at least 130 (= 160-30) mmH ₂ O or more, preferably 140 (= 170-30 = 160-20) mmH ₂ O or more, and more preferably 150 (= 180- 30 = 170-20 = 160-10) mmH ₂ O or more. Furthermore, the second water-resistant pressure P _{2 is} particularly preferably set to 160 (= 180-20 = 170-10) mmH ₂ O or more, and the optimal line 170 (= 180-10) mmH ₂ O or more.

    <Opening>    

The "opening" is a parameter indicating the size of pores (fine pores) in the spunbonded nonwoven fabric. Therefore, if the "opening" is small, the liquid is not easy to penetrate; conversely, if the "opening" is large, the liquid is more likely to penetrate. The smaller the "opening", the higher the "water pressure resistance" described above.

However, as the water pressure applied by the side panel 20 increases, the spunbond nonwoven fabric will stretch and cause the "openings" to become larger. Therefore, strictly speaking, the size of the "openings" and the "water pressure resistance" are not linear (linear )correspond. Moreover, the pore size of the spun-bonded nonwoven fabric is not uniform but fluctuates. Therefore, it is difficult to directly use the "opening" system as a corresponding parameter of "water pressure resistance".

Here, as the corresponding parameter of the “opening”, “fineness” and “basis weight” that do not change regardless of the height of the water pressure applied to the side panel 20 are used.

Corresponding parameters of the fiber diameter (thickness) and cross-sectional area of the so-called "fineness" fiber are expressed by weight per predetermined length. Here, the gram number [Danny] per 9000m of the relevant fiber is used as "fineness". Therefore, the smaller the "fineness" of the spunbond nonwoven fabric, the finer the fiber diameter.

In addition, since the fiber diameter of the spun-bonded nonwoven fabric varies, the average value of the "fineness" of the fiber is adopted as a parameter. Therefore, the average "fineness" of a fiber is simply called "fineness".

The so-called "basis weight" is a parameter corresponding to the thickness of the nonwoven fabric or the degree of lamination, and is expressed by the weight per unit area. Here, the number of grams per square meter is set to "basis weight".

Based on the same "basic weight", the smaller the "fineness", the smaller the fiber diameter, and the more the number of fibers (the number of fibers), the smaller the "opening". Moreover, on the basis of the same "fineness", the larger the "basis weight", the more the number of fibers increases, so it can be said that the "opening" is smaller.

The side sheet 20 of this embodiment is a spun-bonded non-woven fabric having a "denier" of 0.1 to 1.0 denier and a "basic weight" of 8 to 20 g / m ² .

When the "fineness" is less than 0.1 denier, the strength of the fiber is reduced and the fiber diameter is small, so that the spinnability of the fiber is reduced. On the other hand, if the "fineness" is greater than 1.0 denier, the "opening" is likely to become large because the fiber diameter is large. This "fineness" is preferably 0.2 to 0.8 denier, and more preferably 0.4 to 0.6 denier from the viewpoint of ensuring the spinnability of the fiber and suppressing "opening".

If the "basis weight" is less than 8 g / m ² , the thickness and strength may be reduced, and thus the formability of a spun-bonded nonwoven fabric may be reduced. On the other hand, if the "basis weight" is more than 20 g / m ² , the thickness and strength increase, and there is a possibility that the touch (skin touch) of the spun-bonded nonwoven fabric may decrease. The "basis weight" is preferably from 10 to 18 g / m ² and more preferably from 12 to 16 g / m ² from the viewpoint of considering both the formability and the feel of the spunbond nonwoven fabric.

By setting the "fineness" and "basis weight" within the above-mentioned predetermined ranges, the side sheet 20 of the spunbond nonwoven fabric can suppress the decrease in strength, and the fibers which are thinner than the fibers of the conventional spunbond nonwoven fabric are designed with high density. , You can reduce the "opening". Therefore, the spun-bonded nonwoven fabric used for the side sheet 20 can ensure a predetermined water resistance.

    <Embossed area ratio>    

The "embossed area ratio" refers to the ratio of the total planar area of the embossed portion to the total planar area of the spunbond nonwoven fabric. Here, when the total planar area of the spunbonded nonwoven fabric is "S1" and the total planar area of the embossed portion is "S2", the percentage of "S1" to "S2" (= <S1 / S2 > × 100) is set to "embossed area ratio".

The side panel 20 of this embodiment uses a spun-bonded nonwoven fabric having an "embossed area ratio" of 5 to 25%.

If the "embossed area ratio" is less than 5%, the spun-bonded nonwoven fabric is prone to fluff, and there is a possibility that the setting properties of the side panel 20 are reduced. On the other hand, if the "embossed area ratio" is more than 25%, the strength or rigidity of the side sheet 20 is increased, and there is a possibility that the touch feeling may be reduced. This "embossed area ratio" is preferably from 6 to 20% from the viewpoint of taking into consideration both the shape and the feel of the side panel 20. In addition, the larger the "embossed area ratio", the higher the water pressure resistance of the spun-bonded nonwoven fabric tends to be higher.

    <Other>    

The side sheet 20 of this embodiment may use a spun-bonded nonwoven fabric in which fibers are oriented in a specific direction, or a spun-bonded nonwoven fabric in which fibers are irregularly aligned.

When the former spun-bonded non-woven fabric is used, strength and rigidity (anisotropic) can be ensured in a specific direction, so that the degree of freedom in designing an absorbent article can be improved. In the case of the latter spun-bonded non-woven fabric, since the variation in strength and rigidity (isotropic) can be suppressed, the side sheet 20 can be arranged without considering the alignment, which contributes to the manufacturing workability of the absorbent article. Promotion.

    [2-2. Chemical composition]    

Next, the chemical constitution of the side sheet 20 of the spunbonded nonwoven fabric will be described. The chemical composition described later is an example of ensuring the fiber spinnability under the condition that the fiber diameter used for the spin-bonded nonwoven fabric forming the side sheet 20 is suppressed.

The fiber of the spun-bonded nonwoven fabric forming the side sheet 20 is a polyolefin resin. This polyolefin resin contains polypropylene (PP). The term "polyolefin resin" as used herein may include polyethylene (PE).

The polypropylene can be roughly classified into low-crystalline polypropylene (low-crystalline polyolefin resin) having a melting point of less than 100 ° C, and high-crystalline polypropylene (high-crystalline polyolefin resin) having a melting point of 100 ° C or higher. Examples of the highly crystalline polypropylene are propylene homopolymer, propylene random copolymer, and propylene block copolymer. The related low-crystalline polypropylene is described in detail in the following item [2-2-2].

    [2-2-1. Polyolefin resin]    

The melt flow rate (also referred to as "MFR") of the polyolefin resin is preferably 20 to 100 g / 10 minutes. In addition, the "melt flow rate" is a measure of the fluidity of a resin in a solution state. The larger the value, the more the fluidity and moldability are improved, but the tensile strength tends to decrease.

If the melt flow rate is less than 20 g / 10 minutes, there is a possibility that the spinnability of the fiber formed from the polyolefin resin may decrease. On the other hand, if the melt flow rate is more than 100 g / 10 minutes, the side sheet 20 made of a spun-bonded nonwoven fabric formed of a polyolefin resin may have a reduced touch. Therefore, the melt flow rate of the polyolefin resin is more preferably 20 to 90 g / 10 minutes and particularly preferably 20 to 80 g / 10 minutes from the viewpoint of ensuring spinnability and feel.

In addition, other thermoplastic resins and additives may be mixed into the polyolefin resin used.

The other thermoplastic resin may contain an olefin-based polymer. Examples of the olefin-based polymerization system include a propylene-ethylene copolymer, a propylene-ethylene-diene copolymer, an ethylene / α-olefin copolymer, an ethylene-vinyl acetate copolymer, and a hydrogenated styrene-based elastomer. These systems can be used alone or in combination of two or more.

Examples of the additive system include lubricants, foaming agents, crystal nucleating agents, weather-resistant stabilizers, ultraviolet absorbers, light stabilizers, heat-resistant stabilizers, antistatic agents, release agents, flame retardants, synthetic oils, waxes, Electrical property improver, anti-slip agent, anti-caking agent, viscosity modifier, anti-staining agent, anti-fog agent, pigment, dye, plasticizer, softener, anti-aging agent, hydrochloric acid absorbent, chlorine trapping agent, antioxidant , Anti-adhesives, etc.

    [2-2-2. Low-crystalline polypropylene]    

Next, the chemical composition of the low-crystalline polypropylene used will be described in detail.

First, the basic stereoregularity (sequence) of the low-crystalline polypropylene used will be described. Here, the two-unit stereo rule in which the two side chain methyl groups are aligned in the same direction is referred to as "meso <m>", and the two unit stereo in which the two side chain methyl groups are aligned in different directions from each other The rule is called "racemic <r>". In addition, a stereo rule arranged by two two-unit groups is called a "triad sequence", and a stereo rule arranged by three two-units is called a "pentad sequence".

Examples of the triad sequence system are: meso triad <mm>, racemic triad <rr>, triad <mr>. The meso triad is composed of two meso-arranged three-dimensional rules. The meso triad is composed of two meso-arranged three-dimensional rules. The triad is in the order of meso and racem. Arranged three-dimensional rules.

Examples of the pentad sequence system are: meso pentad <mmmm>, racemic pentad <rrrr>, racemic meso rac meso pentad <rmrm>. The meso-pentad is composed of three meso-arranged stereo rules, the meso-pentad is composed of three meso-arranged stereo rules, the racemic meso-racemic meso-pente The group is a three-dimensional rule arranged in the order of racem, meso, racem and meso.

In addition, the proportions of the above-mentioned various stereo rules in the low-crystalline polypropylene used (here, set as a percentage) are defined according to the name of {"stereo-rule name" + "fraction"} [mol%]. For example: in the low-crystalline polypropylene used, the proportion of the meso pentad is the meso pentad component ratio, and the proportion of the meso meso Meso Racemic meso-pentad component ratio.

The low-crystalline polypropylene used is, for example, a crystalline polypropylene whose stereoregularity is slightly broken. Specifically, it is preferable to use a low-crystalline polypropylene that satisfies the following <characteristic a> to <characteristic h>.

    <Characteristic a> meso pentad component ratio    

The meso pentad composition ratio is preferably 30 to 80 mole%.

If the meso pentad component ratio is less than 30 mol%, there is a possibility that the low-crystalline polypropylene has a slow curing after melting and a reduction in fiber formability. On the other hand, if the meso pentad component ratio is more than 80 mol%, the low crystallinity polypropylene may have too high crystallinity, which may cause the fiber to be easily broken and the fiber formability may be reduced. Therefore, from the viewpoint of ensuring fiber formability, the meso pentad component ratio is preferably 40 to 70 mole%, and more preferably 50 to 60 mole%.

    <Characteristic b> Ratio of meso pentad fraction and racemic pentad fraction    

When the meso pentad component ratio is set to "A" and the meso pentad component ratio is set to "B", it is preferable to satisfy the inequality I "B / (1-A) ≦ 0.1".

The left side of Inequality I can be set as an index indicating the uniformity of the regular distribution of low-crystalline polypropylene, and the larger the value, the more it will cause sticking. Therefore, from the viewpoint of surely suppressing stickiness, a better system satisfies the inequality I '"B / (1-A) ≦ 0.05", and a particularly good system satisfies the inequality I "" B / (1-A) ≦ 0.04 ".

    <Characteristic c> Racemic meso racemic meso five unit composition ratio    

The racemic meso racemic pentad unit ratio is preferably greater than 2.5 mole%.

If the racemic meso meso pentad component ratio is less than 2.5 mol%, the randomness of the low-crystalline polypropylene is reduced, which is caused by the crystallization of the same-chain polypropylene block chains. Increased crystallinity. Therefore, there is a possibility that the fibers are easily broken and the fiber formability is reduced. Therefore, from the viewpoint of ensuring the fiber formability, the racemic meso racemic pentad unit ratio is preferably greater than 2.6 mole%, and more preferably greater than 2.7 mole%.

In addition, the upper limit of the racemic meso-meso five unit composition rate is generally about 10 mole%. Therefore, the racemic meso racemic pentad component ratio is preferably 10 mol% or less.

    <Characteristic d> Ratio of meso triad component ratio, racemic triad component ratio, and triad component ratio    

When the meso triad composition ratio is set to "C", the meso triad composition ratio is set to "D", and the triad composition ratio is set to "E", it is preferable to satisfy inequality II "C × D / E ² ≦ 2.0 ”.

The left side of Inequality II can be set as an index indicating the randomness of the polymer. The smaller the value, the more the randomness tends to increase. Therefore, the higher the randomness of the polymer, the less likely it is that the fibers will break and the sticking will be suppressed. Therefore, it is better to ensure the fiber formability while suppressing the excessive increase in randomness, and to suppress the sticking. The system satisfies the inequality II '"0.2 ≦ C × D / E ² ≦ 2.0”, and the particularly good system satisfies the inequality II ”“ 0.25 ≦ C × D / E ² ≦ 1.8 ”.

    <Characteristic e> Weight average molecular weight    

The low-crystalline polypropylene used preferably has a weight average molecular weight of 10,000 to 200,000.

When the weight-average molecular weight is less than 10,000, the viscosity of the low-crystalline polypropylene is too low, which may cause the fibers to be easily broken and the fiber formability to be reduced. On the other hand, if the weight-average molecular weight is more than 200,000, there is a possibility that the spinnability of the fiber is lowered because the viscosity of the low-crystalline polypropylene is too high. Therefore, the weight average molecular weight is more preferably from 30,000 to 100,000, and particularly preferably from 40,000 to 80,000 from the viewpoint of considering both the fiber formability and the spinnability.

    <Characteristic f> Molecular weight distribution (ratio of weight average molecular weight and number average molecular weight)    

When the weight-average molecular weight is “Mw” and the number-average molecular weight is “Mn”, the low-crystalline polypropylene used preferably satisfies the inequality III “Mw / Mn ≦ 4”.

The left side of Inequality III can be set as an index indicating the adhesion of fibers. If it is greater than 4, the fibers are liable to adhere. Therefore, from the viewpoint of suppressing sticking, a better system satisfies inequality III '"Mw / Mn ≦ 3", and a particularly good system satisfies inequality III "" Mw / Mn ≦ 2 ".

    <Characteristic g> Amount of boiling diethyl ether extract    

The low-crystalline polypropylene used is preferably 0 to 10% by mass of the boiling diethyl ether extract.

The amount of boiling diethyl ether extract can be used as an indicator of fiber stickiness, and the larger the value, the easier it becomes. Therefore, the amount of boiling diethyl ether extract is more preferably 0 to 5 mass% from the viewpoint of suppressing stickiness of fibers.

    <Characteristic h> Mass ratio of low crystalline polypropylene    

The mass ratio of the low-crystalline polypropylene used is preferably 5 to 50% by mass based on the total solid content. The "total solid content" as used herein means the total amount of low-crystalline polypropylene and high-crystalline polypropylene.

If the mass ratio is less than 5% by mass, the disadvantages of the highly crystalline polypropylene cannot be compensated, the number of triggers will not be increased, and the fiber diameter will not be easily reduced. On the other hand, if the mass ratio is within the above-mentioned mass% range, because it does contain low-crystalline polypropylene, the fibers are not easily broken, and the spinnability is improved, so that fibers with smaller diameters can be stably produced. From this point of view, the mass ratio of the low-crystalline polypropylene is more preferably 10 to 50% by mass, and particularly preferably 20 to 50% by mass.

    <Others>    

The method for producing low-crystalline polypropylene that satisfies the above-mentioned <characteristic a> to <characteristic h> can be a method using a metallocene catalyst and a production method described in Japanese Patent No. 4242498.

    [3. Functions and effects]    

Since the paper diaper is constituted as described above, the following actions and effects can be obtained.

(1) According to the paper diaper according to this embodiment, since the spun-bonded nonwoven fabric serving as the side sheet 20 has a predetermined water resistance, it is possible to prevent the excreted liquid from penetrating through the side sheet 20 and to prevent the leakage of liquid. Therefore, the comfort of the wearer can be ensured.

After all, conventional paper diapers do not have the idea of making the spunbond nonwoven fabric water resistant.

The reason may be, for example, that it is difficult to balance water resistance and touch. For example, if the basis weight of the spun-bonded nonwoven fabric is large, the water resistance can be ensured, but the feel is easily reduced. On the contrary, if the basis weight of the spun-bonded nonwoven fabric is suppressed to ensure the touch, it is difficult to ensure water resistance.

Therefore, for sanitary products or absorbent articles, such as paper diapers, which are premised on ensuring touch, there are background factors that make it difficult to produce a water-resistant spunbond nonwoven fabric.

On the other hand, the paper diaper of the present embodiment is put on the ground based on a new idea of making a spun-bonded nonwoven fabric with a predetermined water resistance. In other words, by making the spun-bonded nonwoven fabric used for the side panel 20 a new structure with a predetermined water resistance and suppressing the leakage of the liquid, it is possible to provide a paper diaper ensuring the comfort of the wearer.

(2) In the conventional paper diaper, an SMS non-woven side sheet is used. If water pressure is applied, the spun-bonded non-woven layer will not be damaged, but the melt-blown non-woven layer may be damaged. As a result, the water pressure resistance of the damaged SMS nonwoven is lower than the water pressure corresponding to the opening of the spunbond nonwoven layer under the SMS nonwoven before the breakage, which is significantly lower than the water pressure of the corresponding hole of the meltblown nonwoven layer. Therefore, it is known to use an SMS non-woven side sheet. When repeated application of water pressure, the water pressure resistance is easily reduced, and the reduced water pressure resistance may not meet the required water pressure resistance.

On the other hand, the side sheet 20 of this embodiment is a spun-bonded nonwoven fabric which can suppress a decrease or change in water pressure resistance even if water pressure is repeatedly applied. Therefore, when the wearer intermittently discharges liquid (that is, even when water pressure is repeatedly applied to the side panel 20), the liquid leakage situation can be continuously suppressed.

Specifically, the first water-resistant pressure P _{1 is} set to 160 mmH ₂ O or more, and the predetermined pressure P _{P of the} amount of decrease from the first water-resistant pressure P ₁ to the second water-resistant pressure P ₂ is set to 30 mmH ₂ O or less. That is, the second water pressure resistance P _{2 is} at least 130 (= 160-30) mmH ₂ O or more. Accordingly, the water resistance pressures P ₁ and P ₂ are higher than those necessary to prevent leakage of the discharged liquid. Therefore, it is possible to surely continuously suppress the leakage. In other words, it is possible to suppress the predetermined pressure P _P and to suppress a decrease in the leakage prevention function.

(3) Furthermore, in the conventional paper diaper, the side sheet of the SMS non-woven fabric is used to ensure water resistance and feel by using a melt-blown non-woven fabric, and to ensure strength by spinning and bonding the non-woven fabric. Therefore, water resistance and touch are not ensured by spinning and bonding non-woven fabrics, but by melt-blown non-woven fabrics.

In contrast, the side panel 20 is a fiber having a smaller diameter than the fiber used in the conventional spun-bonded nonwoven fabric at a high density. Specifically, a spin-bonded nonwoven fabric having a "fineness" of 0.1 to 1.0 denier and a "basic weight" of 8 to 20 g / m ² was used for the side sheet 20. Therefore, the side sheet 20 not only has a predetermined water resistance, but also ensures a tactile feeling.

(4) Furthermore, a part of the side sheet 20 is formed by overlapping two sheet portions 20a and 20b. Therefore, the water pressure resistance of the side sheet 20 can be increased at the place where the two sheet portions 20a and 20b overlap.

Therefore, the two sheet portions 20a and 20b are merely folded and overlapped, and are not integrated in the overlapping direction. Therefore, compared with the side panel with twice the "base weight", it is possible to suppress a decrease in touch due to an increase in rigidity. In short, it is possible to suppress the sheet portions 20a and 20b from becoming stiff (rough and rough feeling).

(5) As described above, in addition to having a predetermined water resistance, the side sheet 20 also ensures the touch. Therefore, the side panel 20 can be arrange | positioned on the close | fitting side which requires a touch in a paper diaper. On the other hand, by disposing the spunbond non-woven fabric side sheet 20 in the paper diaper on the side of the body, it is possible to suppress the leakage of the liquid and ensure the touch.

(6) Similarly, since the side panel 20 is not only provided with a predetermined water resistance, but also can ensure the touch, the side panel 20 can be used for the three-dimensional pleats 21 that specifically require the touch in the paper diaper. Conversely, in the paper diaper in which the side panel 20 is used for the three-dimensional pleats 21, in addition to suppressing the occurrence of liquid leakage in the width direction, the touch feeling can also be ensured. Therefore, the comfort of the wearer can be ensured.

    [II. Examples]    

Hereinafter, examples of this case will be described.

In addition, the materials, usage amounts, proportions, processing contents, processing procedures, and the like shown in the following examples can be appropriately changed before the subject matter of the present case is avoided. Therefore, the scope of this case cannot be limited by the specific examples shown below.

    [1. Manufacturing method of non-woven fabric]    

First, referring to Table 1 above, the resin used in the nonwoven material will be described.

As the resin A, a polypropylene-based polyolefin resin (highly crystalline polypropylene) was used. This resin A has a melting point of 162 ° C and a melt flow rate of 30 g / 10 minutes.

The resin B is a polypropylene-based polyolefin resin (low-crystalline polypropylene) that satisfies the above-mentioned <characteristic a> to <characteristic h>. This resin B has a melting point of 52 ° C and a melt flow rate of 45 g / 10 minutes.

A mixture was prepared by mixing the resin A and the resin B in the ratio shown in Table 1. That is, a nonwoven fabric is produced by spinning polypropylene fibers.

Hereinafter, a method for producing a spunbonded nonwoven fabric (Examples 1 to 6 and Comparative Examples 4 to 6) will be described.

First, the resin A and the resin B are melted by an extruder to obtain a melt. Next, the melt was discharged from a spinning nozzle, and polypropylene fibers were spun. Then, the spun polypropylene fiber is cooled by the cooling air, and the stretched air is used to apply a tension to a predetermined fineness (the fineness shown in Table 1), which is directly collected on the conveyor belt and becomes a predetermined basis weight (Table Basis weight shown in Figure 1). Then, heat and pressure were applied to the accumulated polypropylene fibers by an embossing roller, and a part of them was melted at a predetermined embossed area ratio (embossed area ratio shown in Table 1) to interweave the fibers. Thus, the nonwoven fabrics of Examples 1 to 6 and Comparative Examples 4 to 6 were obtained.

Next, a method for manufacturing the SMS nonwoven fabric (Comparative Examples 1 to 3) will be described.

The manufacturing method is to accumulate polypropylene fibers that become spunbonded nonwoven fabric, accumulate meltblown nonwoven fabric, and then accumulate polypropylene fibers that become spunbonded nonwoven fabric again. In addition, the formation and accumulation of the polypropylene fibers that become the spun-bonded nonwoven fabric are the same as those described above.

Specifically, a melt-blown nonwoven fabric having a predetermined basis weight (basis weight shown in Table 1) was formed on a fiber web accumulated with polypropylene fibers to be spun-bonded nonwoven fabric by a melt-blown method. On top of this, the polypropylene fibers that became the spunbond nonwoven fabric accumulated again. Then, in the same manner as in the method for manufacturing a spunbonded nonwoven fabric, heat and pressure are applied by an embossing roller, and a part of them is melted according to a predetermined embossed area ratio (embossed area ratio shown in Table 1), and the fibers are entangled. Thus, the nonwoven fabrics of Comparative Examples 1 to 3 were obtained.

    [2. Measurement method and evaluation method]    

The measurement methods or evaluation methods for deriving the results shown in Table 1 above are shown in the following <Method i> to <Method vi>. In addition, the methods for evaluating the chemical composition are shown in <Method vii> to <Method x>.

    <Method i> Melt flow rate    

Melt flow rate is based on Table 1 of JIS-K7210 "Test Method for Melt Mass Flow Rate (MFR) and Melt Volume Flow Rate (MVR) of Plastics-Thermoplastic Plastics" using a melt index tester (manufactured by Toyo Seiki Co., Ltd.) : MELTINDEXERS-101) Melt-flow device, measured according to a spinneret diameter of 2.095mm, a spinneret hole length of 0.8mm, and a load of 2160g. The measurement was performed at a measurement temperature of 230 ° C., and the amount of molten polymer discharged (g) per 10 minutes was calculated from the time required to discharge a certain volume.

    <Method ii> Fineness    

The fineness is obtained by excluding approximately 10 cm of the two ends of the manufactured nonwoven fabric, roughly five equal parts in the width direction, and sampling a 1 cm square test piece. The fiber diameters at each of the 20 locations were measured with a microscope, and calculated from the average value.

    <Method iii> Basis weight    

The basis weight was obtained by removing 10 cm of both ends of the manufactured nonwoven fabric, arbitrarily taking five test pieces having a length of 20 cm × width 20 cm, measuring the mass, and converting the average value to the weight per unit area.

    <Method iv> Embossed area ratio    

The embossed area ratio is obtained by excluding the two ends of the manufactured non-woven 10 cm, approximately five equal parts in the width direction, and sampling a 1 cm square test piece. The magnified image of the non-woven fabric was taken with a microscope, and the image processing program was used to measure the corresponding embossing. The area ratio of the recessed portions of the non-woven fabric was 20 each, and the average value was calculated.

    <Method v> Water resistance    

The water pressure resistance is measured according to ISO811 or JIS L1092.

The measurement of the water pressure resistance will be described in detail below.

When measuring the water pressure resistance, the obtained non-woven fabric was cut into eight pieces of 20 cm square, and the cut non-woven fabric was mounted on a sample support for a water pressure tester FX-3000 made by TEXTEST. The non-woven fabric to be installed is one or two pieces, and the measurement area is set to 100 cm ² without wrinkles.

Then, in the pressure test mode, the water pressure was increased at a rate of 600 mmH ₂ O / min, and the water pressure resistance was measured. In this measurement, the pressure at three or more places where the water leaks is set as the water pressure resistance.

When repeating the measurement of the water pressure resistance, the sample subjected to the water pressure measurement is removed from the tester, and the water is wiped from both sides (front and back) of the non-woven sheet with a paper towel or the like while it is mounted on the sample support. The nonwoven fabric was mounted on the tester again, and the water pressure resistance was measured in the same procedure.

    <Method vi> Touch    

The tactile sensation was obtained by removing 10 cm at both ends of the manufactured non-woven fabric, arbitrarily taking five test pieces with a length of 20 cm x a width of 20 cm, and setting them as measurement samples. This evaluation is divided into three levels: "○" (good), "△" (normal), and "×" (poor).

    <Method vii> Molecular weight distribution    

The relevant equipment and conditions for measuring the molecular weight distribution are as follows:

GPC measuring device

Column: TOSO GMHHR-H (S) HT

Detector: RI detector WATERS150C for liquid chromatography

Measurement conditions

Solvent: 1,2,4-trichlorobenzene

Measurement temperature: 145 ° C

Flow rate: 1.0ml / min

Sample concentration: 2.2mg / ml

Injection volume: 160μl

Calibration line: Universal

Calibration

Parser: HT-GPC (Ver.1.0)

    <Method viii> Boiling diethyl ether extraction amount    

The relevant equipment and conditions for the determination of the boiling diethyl ether extraction amount are as follows:

Soxhlet Extractor

Measurement conditions

Extraction sample: 5 ~ 6g

Sample shape: powder (used after pulverizing the granulated material)

Extraction solvent: diethyl ether

Extraction time: 10 hours

Extraction times: more than 180 times

Extraction volume calculation method: Calculated by the following formula.

[Amount extracted from diethyl ether (g) / Weight of filling powder (g)] × 100

    <Method ix> Meso pentad fraction, racemic pentad fraction, and racemic meso racpentad fraction    

The ratio of each stereoregularity in the low-crystalline polypropylene used for spinning the bonded nonwoven fabric was determined by measuring a 13C-NMR mass spectrum. This measurement was performed in accordance with the spike assignment proposed by A. Zambelli et al. In "Macromolecules, 8, 687 (1975)".

The devices and conditions related to this measurement are listed below: Device: JNM-EX400 13C-NMR device manufactured by Japan Electronics Co., Ltd.

Method: Proton Total Hydrogen Decoupling

Concentration: 220mg / ml

Solvent: 90:10 mixed solvent of 1,2,4-trichlorobenzene and heavy benzene

Temperature: 130 ℃

Pulse width: 45 °

Pulse repetition time: 4 seconds

Points: 10,000 times

<Calculation formula>

M = m / S × 100

R = Y / S × 100

S = P _ββ + P _αβ + P _αY

S: Signal strength of the side chain methyl carbon atom of the total propylene unit

P _ββ : 19.8 ~ 22.5ppm

P _αβ : 18.0 ~ 17.5ppm

P _αY : 17.5 ~ 17.1ppm

Y: racemic pentad unit chain: 20.7 ~ 20.3ppm

m: meso pentad unit chain: 21.7 ~ 22.5ppm

    <Method x> Melting point and crystallization temperature    

Melting points and crystallization temperatures were obtained according to the following apparatus and method.

Using a differential scanning calorimeter (manufactured by PerkinElmer, DSC-7), 10 mg of the sample was preliminarily melted at 230 ° C for 3 minutes under a nitrogen environment, and then cooled down to 0 ° C at 10 ° C / min. The maximum peak of the crystal exothermic curve obtained at this time was set as the crystallization temperature. Furthermore, after further holding at 0 ° C for 3 minutes, the maximum peak peak of the melting endothermic curve obtained by increasing the temperature at 10 ° C / min was taken as the melting point.

    [3. Investigation]    

Next, the nonwoven fabrics of Examples 1 to 6 and Comparative Examples 1 to 6 were examined.

    <Example>    

First, the spunbonded nonwoven fabrics of Examples 1 to 6 will be examined.

In the spunbonded nonwoven fabrics of Examples 1 to 6, the water pressure resistance (the first water pressure resistance P ₁ ) and the water pressure pressure (the second water pressure resistance P ₂ ) measured in the first measurement were 130 mmH ₂ O or more. Higher than necessary to prevent leakage of drained liquid. In addition, the amount of reduction (predetermined pressure P _P ) from the first measurement of the water pressure resistance to the second measurement of the water pressure resistance (the second water pressure P ₂ ) was suppressed to 30 mmH ₂ O or less.

Based on this, related to the reason that the liquid leakage prevention function can be reliably prevented, and the reduction of this function can be suppressed. For Examples 1 to 5, according to the above-mentioned "fineness" and "basis weight", the use of small-diameter fibers with high density can be considered as spinning and bonding. The non-woven fabric is caused by a reduction in strength and a predetermined water resistance.

If the water pressure resistance measured in the first and second measurements is observed in detail, Examples 3 and 4 are 160 ~ 170mmH ₂ O, Examples 1, 2 and 6 are 170 ~ 180mmH ₂ O or more, and Example 5 are 200mmH ₂ O or more.

The reason why the water pressure resistance measured in Example 5 is higher than those in Examples 1 to 4, 6 is that it is considered that Examples 1 to 4, 6 use one piece of spunbond nonwoven fabric, while the relative example 5 uses two pieces of spunbond non-woven fabric. Non-woven fabrics are used after overlapping.

Furthermore, if the reduction in the water pressure resistance measured from the first measurement to the second water pressure reduction (predetermined pressure P _P ) is taken into consideration, Examples 1 to 6 are all below 10 mmH ₂ O, especially Examples 1 and 6 are 0 mmH ₂ O.

Based on this, the reason that the water pressure resistance can be maintained in Examples 1 and 6 is considered to be because the embossed area ratio is higher than in other Examples 2 to 5. It is considered that Example 6 was caused by a larger basis weight than that of Examples 1 to 5.

In addition, the spun-bonded nonwoven fabrics of Examples 1 to 5 also obtained "○" in terms of evaluation of touch.

It is considered that a good reason for the tactile evaluation was that the spun-bonded nonwoven fabric was made by using small-diameter fibers at a high density as described above.

In addition, although the spun-bonded nonwoven fabric of Example 6 had a water pressure resistance of 130 mmH ₂ O or more measured for the first time and the second time, the tactile evaluation was "×".

Based on this reason for the low tactile evaluation, it is considered that because the "fineness" and "basic weight" are larger than the spun-bonded nonwoven fabrics of Examples 1 to 5, thick layers of coarse fibers result in the rigidity of the nonwoven fabric. It is caused by the stiffness.

    <Comparative example>    

Next, the nonwoven fabrics of Comparative Examples 1 to 6 were examined.

Although the SMS nonwoven fabrics of Comparative Examples 1 to 3 had a water pressure resistance of 160 mmH ₂ O or more in the first measurement, the water pressure resistance in the second time was less than 130 mmH ₂ O. That is, in the SMS nonwoven fabrics of Comparative Examples 1 to 3, the decrease in the water pressure resistance measured at the first time to the pressure water resistance measured at the second time was greater than 30 mmH ₂ O. Moreover, the water pressure resistance measured this second time is lower than the water pressure necessary to prevent leakage of the discharged liquid.

Based on this, the reason why the decrease in the water pressure resistance was not suppressed, and the second time the water pressure resistance measured to be low was considered to be the following reason.

In the SMS nonwoven fabrics of Comparative Examples 1 to 3, the "base weight" of the spun-bonded nonwoven fabric layer was smaller than that of the spun-bonded nonwoven fabrics of Examples 1 to 6. In the SMS nonwoven fabrics of Comparative Examples 1 to 3, the "fineness" of the nonwoven fabric layer was larger than that of the spun-bonded nonwoven fabrics of Examples 1 to 5, and therefore the "openings" were large. On the other hand, in the SMS nonwoven fabrics of Comparative Examples 1 to 3, although the "blown hole" of the meltblown nonwoven fabric layer was smaller than that of the spun-bonded nonwoven fabrics of Examples 1 to 6, the strength was low.

Therefore, in the SMS nonwoven fabrics of Comparative Examples 1 to 3, it is considered that the melt-blown nonwoven fabric layer was damaged during the first water pressure measurement, and the "openings" (fineness and basis weight) of the spunbond nonwoven fabric were set around the damaged area. The corresponding water pressure resistance was measured the second time.

In addition, in the SMS nonwoven fabrics of Comparative Examples 1 to 3, the tactile evaluation was "△".

Accordingly, the reason why the tactile evaluation is not good is because the spin-bonded nonwoven fabric layer in the SMS nonwoven fabric has a large "fineness" and therefore has high rigidity and stiffness.

In the spun-bonded nonwoven fabrics of Comparative Examples 4 to 6, the water pressure resistance of 160 mmH ₂ O or less was measured for the first time, and the target water pressure resistance could not be obtained. Therefore, the second water pressure resistance measurement was not performed.

Since the "spunness" of the spun-bonded nonwoven fabric of Comparative Example 4 was larger than that of the spun-bonded nonwoven fabrics of Examples 1 to 5, it was considered that the "opening" was large and the water pressure resistance measured for the first time was low.

The spun-bonded nonwoven fabric of Comparative Example 5 had a smaller "basic weight" than the spun-bonded nonwoven fabrics of Examples 1 to 6, and therefore it was considered that the "opening" was large and the water pressure resistance measured for the first time was low.

Since the spun-bonded nonwoven fabric of the comparative example 6 had a large content of the resin B, it was considered that the fiber used was easily broken and the water pressure resistance measured for the first time was low.

    [III. Variations]    

Finally, another modification of this embodiment will be described.

The side sheet 20 is not limited to being composed of only a spun-bonded nonwoven fabric, and may include a meltblown nonwoven fabric. For example, an SMS nonwoven fabric is used for the side sheet 20. In this case, the above-mentioned spun-bonded nonwoven fabric layer with predetermined water resistance is contained in the SMS nonwoven fabric. If so meltblown non-woven fabric contained in the side panels 20, can be established to ensure water resistance, and can further improve the water pressure resistance of the first P _1, helps to enhance the wearer's comfort.

In addition, the spun-bonded non-woven fabric having a predetermined water resistance is not limited to the side sheet 20, and may be used for other sheets such as the back sheet 14 and the cover sheet 15. In other words, the above-mentioned spun-bonded nonwoven fabric and the sheet used therefor are not limited to absorbent articles such as paper diapers, and can be applied to various articles requiring a predetermined water resistance. In any case, the above-mentioned spun-bonded nonwoven fabric can continuously satisfy the required water pressure resistance. By using the spun-bonded nonwoven fabric, the required water pressure resistance can be continuously satisfied, and other functions can be added to the sheet other than the constituent elements of the spun-bonded nonwoven fabric.

Claims (9)

A spunbond non-woven fabric is a fiber made of a thermoplastic resin, which is characterized in that when the water pressure resistance is repeatedly measured according to ISO811, the second water pressure resistance measured after the second time is relative to the first water resistance pressure measured in the first time. The amount of reduction in pressure is a predetermined water resistance below a predetermined pressure; the first water resistance is 160 mmH ₂ O or more, and the predetermined pressure is 30 mmH ₂ O or less. For example, the spun-bonded non-woven fabric of claim 1, wherein the average fineness of the fibers is 0.1 to 1.0 denier; the basis weight is 8 to 20 g / m ² .     The spun-bonded nonwoven fabric according to claim 1, wherein the thermoplastic resin is a polyolefin resin containing polypropylene.     For example, the spun-bonded nonwoven fabric according to claim 3, wherein the polyolefin resin is a low-crystalline polyolefin resin that satisfies the following matters based on the total solid content of 5 to 50% by mass: the meso pentad component ratio 30 ~ 80 mole%; when the meso pentad component ratio is set to "A" and the racemic pentad component ratio is set to "B", the inequality I "B / (1-A)" is satisfied ≦ 0.1 ”; racemic meso racemic meso five-unit component ratio is greater than 2.5 mole%; set meso three-unit component ratio to“ C ”, racemic three-unit component ratio When it is set to “D” and the triad component ratio is set to “E”, the inequality II “C × D / E ² ≦ 2.0” is satisfied; the weight average molecular weight is 10,000 to 200,000; When the number average molecular weight is set to "Mn", the inequality III "Mw / Mn≤4" is satisfied; the amount of the extract using boiling diethyl ether is 0 to 10% by mass.     A sheet comprising the spunbonded nonwoven fabric according to any one of claims 1 to 4, characterized in that it does not contain a meltblown nonwoven fabric.         For example, the sheet of claim 5, wherein the area ratio of the embossed portion where the fibers are fused to each other is 5 to 25%.         For the sheet of item 6, two or more sheets are overlapped.         An absorbent article characterized by arranging the sheet of claim 5 on the side of the body.         The absorbent article according to claim 8, wherein the sheet is used for a three-dimensional pleated erected on the body-side.