JPWO2020036143A1 - Nonwoven fabric for absorbent articles, its manufacturing method, surface sheet for absorbent articles, and absorbent articles - Google Patents

Abstract

The present invention is a multi-layered non-woven fabric containing a first fiber layer and a second fiber layer, the first fiber layer is made of cotton fiber, the grain size is 5 to 30 g / m2, and the second fiber layer is a synthetic long fiber. It is made of a non-woven fabric and has a texture of 5 to 20 g / m2. The constituent fibers of the first fiber layer and the second fiber layer are three-dimensionally entangled and integrated, and the multi-layered non-woven fabric has holes. The present invention relates to a non-woven fabric for an absorbent article in which the lateral breaking strength of the second fiber layer is 5.0 N / 5 cm or less. Thereby, a nonwoven fabric for absorbent articles, a surface sheet for absorbent articles, and an absorbent article containing the same are provided, which have improved liquid absorption characteristics while increasing the strength of the nonwoven fabric containing cotton fibers.

Description

The present invention relates to a non-woven fabric for absorbent articles used for absorbent articles such as sanitary napkins and paper diapers (including paper diapers for infants and adults), a method for producing the same, a surface sheet for absorbent articles, and an absorbent article. Regarding.

Absorbent articles such as sanitary napkins and disposable diapers are mainly composed of a surface sheet that comes into contact with the wearer's skin, an absorber that absorbs liquid, and a leak-proof sheet that prevents liquid from leaking out of the absorbent article. ing. The surface sheet used for the absorbent article has a soft and smooth touch for comfort when worn, and excretes blood discharged from the body such as menstrual blood, urine, fluid feces, etc. It is required to have excellent liquid absorption characteristics for absorbing substances.

In Patent Document 1, a non-woven fabric composed of a surface layer composed of 30% to 100% cotton fibers having a gram weight of 5 to 50 g / m ^{2 and a non-woven fabric reinforcing layer is used as a skin layer of an absorbent product.} It has been proposed to use it.

Special Table 2016-529412 Gazette

In the nonwoven fabric described in Patent Document 1, the strength of the nonwoven fabric containing cotton is increased by including the nonwoven fabric reinforcing layer, but the nonwoven fabric reinforcing layer may hinder the high liquid absorption characteristics of the cotton fibers.

In order to solve the above-mentioned conventional problems, the present invention provides a nonwoven fabric for absorbent articles having improved liquid absorption characteristics while increasing the strength of the nonwoven fabric containing cotton fibers, a method for producing the same, a surface sheet for absorbent articles, and absorption. Provide sex goods.

The present invention is a multi-layered non-woven fabric containing a first fiber layer and a second fiber layer, the first fiber layer is made of cotton fiber, the grain size is 5 to 30 g / m ² , and the second fiber layer has a synthetic length. It is made of a fibrous non-woven fabric and has a texture of 5 to 20 g / m ² , and the constituent fibers of the first fiber layer and the second fiber layer are three-dimensionally entangled and integrated, and the multi-layered non-woven fabric has holes. The present invention relates to a non-woven fabric for an absorbent article, wherein the second fiber layer has a lateral breaking strength of 5.0 N / 5 cm or less.

In the non-woven fabric for absorbent articles, the stress at 5% elongation in the lateral direction of the second fiber layer is preferably 0.5 N / 5 cm or less. The stress at 5% elongation in the longitudinal direction of the second fiber layer is preferably 3.0 N / 5 cm or less. The second fiber layer is preferably a synthetic long fiber non-woven fabric made of polyester fibers.

The present invention also comprises a fiber web, which is made of cotton fiber and has a grain size of 5 to 30 g / m ² , and is a first fiber layer, and a second fiber layer, which has a grain size of 5 to 20 g / m ^2. The combined growth fiber non-woven fabric is laminated to form a laminated body, and the constituent fibers of the first fiber layer and the second fiber layer in the laminated body are three-dimensionally entangled and integrated, and the laminated body has an open hole structure. By applying it, it is a multi-layered non-woven fabric containing a first fiber layer and a second fiber layer, and a non-woven fabric for an absorbent article having an open hole structure is obtained, and the lateral direction of the second fiber layer in the non-woven fabric for an absorbent article is obtained. The present invention relates to a method for producing a non-woven fiber for an absorbent article, which comprises a breaking strength of 5.0 N / 5 cm or less.

It is preferable that the lateral breaking strength of the synthetic long-fiber nonwoven fabric to be the second fiber layer in the step of forming the laminate is 5.0 N / 5 cm or less.

The present invention also relates to a surface sheet for an absorbent article, which comprises the above-mentioned non-woven fabric for an absorbent article and has a first fiber layer as a skin facing surface.

The present invention also relates to an absorbent article, including the above-mentioned surface sheet for an absorbent article.

INDUSTRIAL APPLICABILITY The present invention can provide a nonwoven fabric for absorbent articles, a surface sheet for absorbent articles, and an absorbent article containing the same, which have improved liquid absorption characteristics while increasing the strength of the nonwoven fabric containing cotton fibers. Further, according to the method for producing a nonwoven fabric for absorbent articles of the present invention, it is possible to obtain a nonwoven fabric for absorbent articles having improved liquid absorption characteristics while increasing the strength of the nonwoven fabric containing cotton fibers.

The inventors have diligently studied to solve the above problems. As a result, a cotton fiber, and basis weight in the first fiber layer is 5 to 30 g / m ^2, laminating the second fiber layer basis weight is made of synthetic filament non-woven fabric is 5 to 20 g / m ^2, the The constituent fibers of the 1st fiber layer and the 2nd fiber layer are three-dimensionally entangled and integrated to form a multilayer nonwoven fabric having openings, and the lateral breaking strength of the 2nd fiber layer in the multilayer nonwoven fabric is 5.0N. It has been found that the liquid absorption characteristics can be improved while increasing the strength of the non-woven fabric containing cotton fibers by setting the thickness to / 5 cm or less.

The non-woven fabric for absorbent articles is a multilayer non-woven fabric including a first fiber layer and a second fiber layer. The first fiber layer is made of cotton fiber and has a basis weight of 5 to 30 g / m ² . By forming the first fiber layer with cotton fibers, the texture becomes soft. Absorbent improve liquid leakage prevention of the article for nonwovens, that is, from the viewpoint of reducing the liquid return amount is preferably basis weight of the first fiber layer is 10 to 25 g / m ^2, in 15~22g / m ² It is more preferable to have.

The cotton fiber constituting the first fiber layer is not particularly limited, but for example, the fineness is preferably 0.5 to 6.0 dtex. From the viewpoint of smoothing the tactile sensation, the fineness is preferably 5.0 dtex or less, and more preferably 4.0 dtex or less. From the viewpoint of increasing the liquid absorption rate, the fineness is preferably 0.6 dtex or more, and more preferably 0.8 dtex or more. The fineness of the cotton fiber can be calculated according to the method using JIS L 1019 7.4.1 Micronea.

The cotton fiber constituting the first fiber layer is not particularly limited, but the fiber length is preferably 1 to 100 mm in consideration of card passability. It is more preferably 10 to 80 mm, still more preferably 15 to 60 mm. The fiber lengths do not have to be all the same. Natural fiber derived from plants, such as cotton fiber, is generally supplied in a form in which the fiber length is not constant, and such a form may be used.

A fiber web can be used as the first fiber layer. Examples of the fiber web include parallel web, semi-random web, random web, cross web, card web such as criss cross web, and air raid web. Since the surface sheet for absorbent articles is required to have bulkiness, flexibility, and an appropriate porosity so that there are some voids between the fibers, the fiber web is preferably a card web.

The second fiber layer is made of a synthetic long-fiber non-woven fabric, and the constituent fibers of the first fiber layer and the second fiber layer are three-dimensionally entangled and integrated. By laminating the first fiber layer made of cotton fiber and the second fiber layer made of synthetic long fiber non-woven fabric to form a multilayer non-woven fabric, the strength of the non-woven fabric for absorbent articles can be increased and the amount of liquid return can be reduced. Can be done. Further, since the long fiber non-woven fabric is used as the second fiber layer, even if the constituent fibers of the first fiber layer and the second fiber layer are three-dimensionally entangled with each other, synthetic fibers are essential on the surface of the first fiber layer. It does not exist and can retain the soft touch peculiar to cotton fibers. Here, "there is essentially no synthetic fiber on the surface of the first fiber layer" means that there is no synthetic fiber on the surface of the first fiber layer or on the surface of the first fiber layer. The presence of a small amount of synthetic fibers means that they have no function or effect.

In the non-woven fabric for absorbent articles, the second fiber layer has a breaking strength of 5.0 N / 5 cm or less in the lateral direction (also referred to as the CD direction). As a result, the entanglement between the constituent fibers of the first fiber layer and the second fiber layer is enhanced, the opening of the non-woven fabric for absorbent articles becomes clear, the fluff is reduced, the texture is improved, and the texture is good. Become. Preferably, the lateral breaking strength of the second fiber layer is preferably 4.0 N / 5 cm or less, more preferably 3.5 N / 5 cm or less, and further preferably 3.0 N / 5 cm or less. It is more preferably 2.5 N / 5 cm or less, further preferably 2.0 N / 5 cm or less, even more preferably 1.5 N / 5 cm or less, and 1.0 N / 5 cm or less. Is even more preferable. From the viewpoint of increasing the strength of the non-woven fabric for absorbent articles, the lateral breaking strength of the second fiber layer is preferably 0.1 N / 5 cm or more, more preferably 0.3 N / 5 cm or more, and 0. It is more preferably 5N / 5cm or more.

In the non-woven fabric for absorbent articles, the second fiber layer is not particularly limited, but is also referred to as a longitudinal direction (also referred to as an MD direction) from the viewpoint of further enhancing the entanglement between the constituent fibers of the first fiber layer and the second fiber layer. The breaking strength of (1) is preferably 10.0 N / 5 cm or less, more preferably 8.0 N / 5 cm or less, and even more preferably 6.0 N / 5 cm or less. It is even more preferably 5 cm or less, even more preferably 2.0 N / 5 cm or less, and even more preferably 1.5 N / 5 cm or less. From the viewpoint of increasing the strength of the non-woven fabric for absorbent articles, the breaking strength of the second fiber layer in the longitudinal direction is preferably 0.3 N / 5 cm or more, more preferably 0.5 N / 5 cm or more, and 0. It is more preferably 7 N / 5 cm or more.

In the non-woven fabric for absorbent articles, the second fiber layer is not particularly limited, but has a lateral breaking elongation of 5 to 100 from the viewpoint of further enhancing the entanglement between the constituent fibers and imparting clearer openings. %, More preferably 10 to 80%, still more preferably 20 to 70%. Further, in the non-woven fabric for absorbent articles, the second fiber layer is not particularly limited, but the breaking elongation in the vertical direction is 20 from the viewpoint of further enhancing the entanglement between the constituent fibers and imparting clearer openings. It is preferably ~ 100%, more preferably 30-80%, and even more preferably 35-70%.

In the non-woven fabric for absorbent articles, the second fiber layer is not particularly limited, but the lateral 5% elongation stress is 0 from the viewpoint of further enhancing the entanglement between the constituent fibers and imparting clearer openings. It is preferably 0.01 to 1.0 N / 5 cm, more preferably 0.02 to 0.9 N / 5 cm, further preferably 0.03 to 0.8 N / 5 cm, and 0.03 to 0.03 to 0.5 cm. Even more preferably, it is 0.2 N / 5 cm. In the non-woven fabric for absorbent articles, the second fiber layer is not particularly limited, but the stress at 5% elongation in the longitudinal direction is 0 from the viewpoint of further enhancing the entanglement between the constituent fibers and imparting clearer pores. It is preferably 0.03 to 10 N / 5 cm, more preferably 0.05 to 8.0 N / 5 cm, further preferably 0.07 to 5.0 N / 5 cm, and 0.07 to 1. Even more preferably, it is 0 N / 5 cm.

The synthetic long fiber non-woven fabric (second fiber layer) has a basis weight of 5 to 20 g / m ^2, which is preferable from the viewpoint of enhancing the entanglement between constituent fibers and imparting clearer pores and cost. Is 7 to 18 g / m ² , more preferably 8 to 15 g / m ² .

The synthetic long fiber nonwoven fabric is not particularly limited, and examples thereof include spunbonded nonwoven fabrics and melt blown nonwoven fabrics. A spunbonded nonwoven fabric is preferable from the viewpoints of cost, entanglement between constituent fibers, clarity of pore opening, strength of the multilayer nonwoven fabric, and high liquid absorption rate.

The synthetic long fiber non-woven fabric may be a non-woven fabric composed of synthetic long fibers, and is not particularly limited. From the viewpoint of reducing the amount of liquid return, it is preferable that the synthetic long fibers are hydrophobic fibers. The hydrophobic fiber may be, for example, a fiber having an official moisture content of 5.0% or less, more preferably 2.0% or less, still more preferably 1.0% or less. The official moisture content is shown in JIS L0105 (2006). If the official moisture content is not known, the value calculated from the following formula is used as the official moisture content.
Official moisture content (%) = [(W-W') / W'] x 100
Here, W means the mass (g) of the fiber in an environment of a temperature of 20 ° C. and a humidity of 65% RH, and W'means the mass (g) when the fiber is completely dried. The mass of the fiber in an environment of a temperature of 20 ° C. and a humidity of 65% RH means the mass when the fiber is left in an environment of a temperature of 20 ° C. and a humidity of 65% RH and reaches a constant mass. The mass at the time of absolute drying means the mass when the fiber is left in a dryer set at 105 ° C. and reaches a constant mass.

The hydrophobic fiber is not particularly limited as long as it is a fiber having an official moisture content of 5.0% or less, and examples thereof include polyester fiber, polyolefin fiber, polyamide fiber, acrylic fiber, vinyl chloride fiber and the like. .. The polyester fiber may be, for example, one or more polyester resins selected from polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid, polybutylene succinate and copolymers thereof. The constituent fibers can be used. As the polyolefin-based fiber, for example, a fiber composed of one or more polyolefin-based resins selected from polypropylene, polyethylene, polybutene-1, and an ethylene-propylene copolymer can be used. As the polyamide fiber, for example, a fiber composed of a polyamide resin such as nylon 6 or nylon 66 can be used. The synthetic long fiber may be a single fiber or a composite fiber. Polyester fibers or polyolefin fibers are preferable from the viewpoint of further reducing the amount of liquid return, and polyester fibers are particularly preferable from the viewpoint of entanglement between constituent fibers.

In the synthetic long fiber nonwoven fabric, the fineness of the synthetic long fiber is not particularly limited, but is preferably 0.6 to 5.0 dtex, for example. From the viewpoint of the uniformity of the basis weight of the synthetic fiber nonwoven fabric, the fineness is preferably 4.5 dtex or less, and more preferably 4.0 dtex or less. From the viewpoint of increasing the liquid absorption rate, the fineness is preferably 0.6 dtex or more, and more preferably 0.8 dtex or more.

The non-woven fabric for absorbent articles is not particularly limited, but for example, a fiber web made of 100% by mass of cotton fibers as the first fiber layer and a synthetic long fiber non-woven fabric as the second fiber layer are laminated and contained in the laminate. It can be produced by three-dimensionally entwining and integrating the constituent fibers of the first fiber layer and the second fiber layer, and by imparting an open hole structure to the laminated body. Specifically, by subjecting the laminate to a water flow entanglement treatment, the constituent fibers of the first fiber layer and the second fiber layer are three-dimensionally entangled and integrated, and the laminate has an open structure. Can be given.

The synthetic long-fiber nonwoven fabric used as a raw material for the second fiber layer preferably has a lateral breaking strength of 5.0 N / 5 cm or less, more preferably 4.0 N / 5 cm or less, and 3.5 N / 5 cm or less. It is more preferably less than or equal to, more preferably 3.0 N / 5 cm or less, and even more preferably 2.5 N / 5 cm or less. As a result, the entanglement between the constituent fibers of the first fiber layer and the second fiber layer is enhanced, the opening of the non-woven fabric for absorbent articles becomes clear, the fluff is reduced, the texture is improved, and the texture is good. Become. From the viewpoint of increasing the strength of the non-woven fabric for absorbent articles, the lateral breaking strength of the synthetic long-fiber non-woven fabric used as the raw material of the second fiber layer is preferably 0.5 N / 5 cm or more, preferably 1.0 N / 5 cm or more. It is more preferably present, and more preferably 1.3 N / 5 cm or more.

The synthetic long-fiber nonwoven fabric used as a raw material for the second fiber layer preferably has a longitudinal breaking strength of 20 N / 5 cm or less, more preferably 18 N / 5 cm or less, and further preferably 16 N / 5 cm or less. It is preferably 10 N / 5 cm or less, and even more preferably. As a result, the entanglement between the constituent fibers of the first fiber layer and the second fiber layer is enhanced, the opening of the non-woven fabric for absorbent articles becomes clear, the fluff is reduced, the texture is improved, and the texture is good. Become. From the viewpoint of increasing the strength of the non-woven fabric for absorbent articles, the longitudinal breaking strength of the synthetic long-fiber non-woven fabric used as the raw material of the second fiber layer is preferably 2.0 N / 5 cm or more, preferably 3.0 N / 5 cm or more. It is more preferable that there is, and it is further preferable that it is 4.0 N / 5 cm or more.

The synthetic long-fiber nonwoven fabric used as the raw material of the second fiber layer is not particularly limited, but for example, from the viewpoint of further enhancing the entanglement between the constituent fibers and imparting clearer pores, the elongation at break in the lateral direction is 3. It is preferably ~ 70%, more preferably 5-60%, even more preferably 7-50%, and even more preferably 7-30%. The synthetic long-fiber non-woven fabric used as a raw material for the second fiber layer is not particularly limited, but for example, from the viewpoint of further enhancing the entanglement between the constituent fibers and imparting clearer openings, the elongation at break in the longitudinal direction. Is preferably 5 to 40%, more preferably 7 to 30%, and even more preferably 8 to 20%.

The synthetic long-fiber nonwoven fabric used as a raw material for the second fiber layer is not particularly limited, but for example, from the viewpoint of further enhancing the entanglement between the constituent fibers and imparting clearer pores, a lateral 5% elongation stress. Is preferably 0.1 to 5.0 N / 5 cm, more preferably 0.5 to 4.0 N / 5 cm, and even more preferably 0.7 to 3.0 N / 5 cm. The synthetic long-fiber non-woven fabric used as a raw material for the second fiber layer is not particularly limited, but has a stress at 5% elongation in the longitudinal direction of 1 from the viewpoint of further enhancing the entanglement between the constituent fibers and imparting clearer pores. It is preferably .5-8.0 N / 5 cm, more preferably 2.0-7.0 N / 5 cm, and even more preferably 3.0-6.0 N / 5 cm.

The water flow entanglement treatment can be carried out by placing the laminated body on a support and injecting a water flow onto one side or both sides of the laminated body. The form of the support is not particularly limited, and a conventionally known support may be used. For example, the warp wire diameter is 0.05 mm to 1.5 mm and the weft wire diameter is 0.05 mm to 1. A plain weave net having a diameter of 5.5 mm and a mesh number of 5 to 110 can be used. Orifices with a hole diameter of 0.05 to 0.5 mm are provided at intervals of 0.5 to 1.5 mm, and a water flow with a water pressure of 1.0 to 10.0 MPa is applied to one or both sides of the laminate. It can be sprayed four times at a time. If the water pressure is less than 1.0 MPa, the entanglement between the fibers becomes insufficient, and fluffing may easily occur in the obtained nonwoven fabric. If the water pressure exceeds 10.0 MPa, the entanglement between the fibers becomes too strong and the texture of the non-woven fabric for absorbent articles may deteriorate, or the entanglement of the cotton fibers progresses excessively and the cotton fibers in the synthetic long fiber non-woven fabric. There is a risk that the abundance of fiber will increase and the amount of liquid return will increase. The water pressure is more preferably 2.0 to 9.0 MPa, further preferably 2.0 to 7.0 MPa, and even more preferably 2.0 to 6.0 MPa. The distance between the nozzle and the laminate may be, for example, 5 to 30 mm or 7 to 20 mm.

Specifically, first, the laminated body is placed on the support, and a water flow having a water pressure of 1.0 to 10.0 MPa is sprayed 1 to 4 times from the surface of the first fiber layer of the laminated body. , The constituent fibers of the first fiber layer and the second fiber layer are three-dimensionally entangled and integrated. At this time, it is preferable to use a plain weave net having a warp wire diameter of 0.05 to 0.2 mm, a weft yarn diameter of 0.05 to 0.2 mm, and a mesh number of 70 to 110 meshes as the support. Next, in order to form openings, the laminate is made into a coarse mesh plain weave net, for example, the warp wire diameter is 0.5 to 1.5 mm, the weft wire diameter is 0.5 to 1.5 mm, and the number of meshes. Is placed on a plain woven net of 5 to 60 mesh, and a water stream having a water pressure of 1.0 to 10.0 MPa is sprayed 1 to 4 times from the surface of the second fiber layer.

Next, the multilayer non-woven fabric obtained by water flow confounding is dried. The drying treatment can be carried out using, for example, a hot air dryer. The drying temperature is preferably a temperature at which thermal adhesion of the fibers does not occur.

The nonwoven fabric for absorbent articles is not particularly limited, but for example, from the viewpoint of having clear pores throughout the nonwoven fabric, the pore opening rate is preferably 5% or more, more preferably 10% or more. It is more preferably 15% or more. The nonwoven fabric for absorbent articles is not particularly limited, but for example, the pore area ^{is preferably 0.5 to 3.5 mm 2} from the viewpoint of having clear pores throughout the nonwoven fabric, and is preferably 0.7. It is more preferably ~ 3.0 mm ^2.

The non-woven fabric for absorbent articles is not particularly limited, but for example, from the viewpoint of strength and texture, the breaking strength in the lateral direction is preferably 3.0 to 30 N / 5 cm, preferably 5.0 to 25 N / 5 cm. It is more preferably 7.0 to 20 N / 5 cm, and even more preferably. Further, the breaking strength in the vertical direction is preferably 10 to 60 N / 5 cm, more preferably 15 to 50 N / 5 cm, and even more preferably 20 to 40 N / 5 cm.

The non-woven fabric for absorbent articles is not particularly limited, but for example, from the viewpoint of processability such as cutting, the elongation at break in the lateral direction is preferably 50 to 200%, more preferably 60 to 180%. It is preferably 70 to 150%, more preferably 70 to 150%. The nonwoven fabric for absorbent articles is not particularly limited, but from the viewpoint of processability such as cutting, the elongation at break in the vertical direction is preferably 10 to 100%, and more preferably 15 to 80%. It is preferably 20 to 60%, more preferably 20 to 60%.

The non-woven fabric for absorbent articles is not particularly limited, but for example, from the viewpoint of strength and texture, the stress at 10% elongation in the lateral direction is preferably 0.3 to 2.5 N / 5 cm, preferably 0.4 to 0.5 cm. It is more preferably 2.0 N / 5 cm, further preferably 0.5 to 1.5 N / 5 cm, and even more preferably 0.6 to 1.2 N / 5 cm. The non-woven fabric for absorbent articles is not particularly limited, but for example, from the viewpoint of strength and texture, the stress at 10% elongation in the vertical direction is preferably 2.0 to 25 N / 5 cm, preferably 3.0 to 20 N /. It is more preferably 5 cm, further preferably 4.0 to 10 N / 5 cm, and even more preferably 5.0 to 9.0 N / 5 cm.

The non-woven fabric for absorbent articles can be used as a surface sheet for absorbent articles. In the absorbent article surface sheet, the first fiber layer abuts on the skin of the wearer wearing the absorbent article. When the first fiber layer made of cotton fiber comes into contact with the skin, it is possible to give a comfortable feeling to the user of the absorbent article.

The surface sheet for absorbent articles includes various absorbent articles such as sanitary napkins, infant paper diapers, adult paper diapers, animal paper diapers such as mammals, panty liners (pantyliner sheets), and incontinence liners. It can be preferably used as a surface sheet.

The absorbent article of the present invention may be any one including the surface sheet for the absorbent article, and is not particularly limited. Examples thereof include sanitary napkins, infant paper diapers, adult paper diapers, paper diapers for animals such as mammals, panty liners (pantyliner sheets), and incontinence liners.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

First, the measurement method and the evaluation method will be described.

(Metsuke)
It was measured according to JIS L 1913 (mass per unit area).

(thickness)
The thickness was measured using a thickness measuring instrument (manufactured by Daiei Kagaku Seiki Seisakusho, trade name "THICKNESS GAUGE", model "CR-60A") with a load of 2.94 cN per ^{1 cm 2 of the sample.}

(Breaking strength, breaking elongation, 5% elongation stress, 10% elongation stress)
According to JIS L 1913 (2010) 6.3, a tensile test was performed using a constant-speed tension type tensile tester under the conditions of a sample piece width of 5 cm, a grip interval of 10 cm, and a tensile speed of 30 ± 2 cm / min. The load value at the time of cutting (tensile strength (breaking strength)), elongation (breaking elongation), and stress at 5% elongation (or stress at 10% elongation) were measured. The tensile test was carried out with the longitudinal direction (MD direction) and the transverse direction (CD direction) of the nonwoven fabric as the tensile direction. The evaluation results are all shown by averaging the values measured for the three samples.

(Opening area, opening rate)
Using a microscope (manufactured by 3R Solution Co., Ltd., model number "3R-MSUSB401"), a 60x magnified photograph of the surface of the non-woven fabric seen from the first fiber layer side was taken, and the image analysis processing software "ImageJ" (free software). ) Is used to binarize the perforated part and the other part of the image, and the ratio of the total area of the perforated part to the total area of the non-woven fabric is calculated. bottom. The photographs were taken at two arbitrarily selected parts (1 cm × 1 cm) of the sample nonwoven fabric, and the average value thereof was taken as the opening rate. The opening area was determined by measuring the area of each opening portion for all the opening portions existing at the two arbitrarily selected locations and calculating the average value thereof.

(Liquid absorption time)
In the absorbent article for evaluation, a plate with an injection cylinder (height 75 mm, inner diameter 25 mm at the upper part of the cylinder, inner diameter 10 mm at the lower part of the cylinder, wall thickness 5 mm, two-stage cylindrical shape) is placed on the sample non-woven fabric. 5.0 cc of artificial menstrual blood (temperature 37 ° C., viscosity 8 mPa · s) was injected into the injection cylinder of the plate with the injection cylinder. The time required for the liquid to disappear from the surface of the non-woven fabric was measured and used as the liquid absorption time (seconds). The composition of artificial menstrual blood is 12.30% by mass of glycerin, 85.18% by mass of ion-exchanged water, 0.45% by mass of CMC (sodium carboxymethyl cellulose), 0.97% by mass of NaCl (sodium chloride), and Na _2. CO ₃ (sodium carbonate) was 1.04% by mass and green powder was 0.06% by mass. After 15 minutes have passed since the measurement of the liquid absorption time, 5.0 cc of artificial menstrual blood (temperature 37 ° C., viscosity 8 mPa · s) was injected again, and the second liquid absorption time (seconds) was measured. Was done.

(Diffusion length)
At the time of the first measurement of the liquid absorption time, 5 minutes after the injection of the artificial menstrual blood, the length of the portion of the sample nonwoven fabric that absorbed the artificial menstrual blood in the MD direction was measured and used as the diffusion length.
Also, when measuring the second liquid absorption time, the diffusion length was measured 5 minutes after the injection of artificial menstrual blood as in the first measurement.

(Amount of liquid return)
In the absorbent article for evaluation, artificial menstrual blood was injected in the same manner as in the first measurement of the liquid absorption time, and 10 minutes after the injection, filter paper (Toyo filter paper) was placed on the non-woven fabric to be the top sheet (surface sheet). Ten sheets of ADVANTEC (registered trademark) No. 2, 10 cm x 10 cm manufactured by Co., Ltd. were placed, and a weight having a mass of 1 kg (shape: square, 10 cm x 10 cm) was placed on a filter paper. Twenty seconds after placing the weight, the filter paper is taken out, the mass of the filter paper that has absorbed artificial menstrual blood is measured, and the mass of the filter paper before being placed on the non-woven fabric is subtracted to calculate the first liquid return amount (g). bottom.
Further, in the absorbent article for evaluation, artificial menstrual blood is injected in the same manner as in the measurement of the second liquid absorption time, and 10 minutes after the injection, the second liquid is used with a filter paper as in the first time. The return amount (g) was calculated.

When measuring the liquid absorption time, diffusion length, and liquid return amount, two samples were prepared for each of the non-woven fabrics of Examples and Comparative Examples. The average values of the liquid absorption time, the diffusion length and the liquid return amount measured for each of the two samples were taken as the liquid absorption time, the diffusion length and the liquid return amount of the nonwoven fabrics of each Example and Comparative Example.

The following are prepared as the synthetic growth fiber non-woven fabric.
^{Combined growth fiber non-woven fabric A: A spunbonded non-woven fabric having a grain size of 10 g / m 2} made of polyethylene terephthalate long fibers (official moisture content: 0.4%) having a fineness of 1.6 dtex (fiber diameter 12.2 μm).
^{Combined growth fiber non-woven fabric B: A spunbonded non-woven fabric having a grain size of 10 g / m 2} made of polypropylene long fibers (official moisture content: 0.0%) having a fineness of 2.3 dtex (fiber diameter 18.0 μm).
The breaking strength, breaking elongation and stress at 5% elongation of the synthetic long fiber nonwoven fabric A and the synthetic long fiber nonwoven fabric B used as raw materials were measured as described above, and the results are shown in Table 1 below.

(Example 1)
<Manufacturing of multilayer non-woven fabric>
Using cotton with a fineness of 1.0 to 5.0 dtex and a fiber length of 10 mm to 60 mm (trade name: MSD, manufactured by Marusan Sangyo Co., Ltd.), a parallel card web with a ^{basis weight of 20 g / m 2 made of cotton fibers was produced.} 1 Used as a fiber layer. A synthetic long fiber nonwoven fabric A was used as the second fiber layer.
The first fiber layer was laminated on the second fiber layer, and the obtained laminate was subjected to water flow entanglement treatment (first water flow entanglement treatment). In the first water flow entanglement treatment, the laminate was placed on a 90-mesh plain weave support made of monofilaments having a wire diameter of 0.132 mm, and nozzles having orifices with a hole diameter of 0.12 mm provided at intervals of 0.6 mm were used. The columnar water flow of 2.0 MPa was sprayed once and the columnar water flow of 3.0 MPa was sprayed once from the surface of the first fiber layer. The transport speed of the support at this time was 4 m / min, and the distance between the nozzle and the laminated body was 10 mm.
Next, a water flow entanglement treatment (second water flow entanglement treatment) for forming an opening was carried out. In the second water flow entanglement treatment, the laminated body after the first water flow entanglement treatment is placed on a 12-mesh plain weave support made of a monofilament having a wire diameter of 1.2 mm, and the same nozzle as that used in the first water flow entanglement treatment is used. Was used to inject a 4.0 MPa columnar water flow once from the surface of the second fiber layer. The transport speed of the support and the distance between the nozzle and the laminated body were the same as in the first water flow entanglement treatment. The laminate after the second water flow entanglement treatment was dried with a hot air dryer at 100 ° C. to obtain the multilayer non-woven fabric of Example 1.
The resulting multilayer nonwoven has approximately 0.5 to 2.0 mm ² openings (mean 1.2 mm ^2), the hole area ratio was 24%, has a generally clear apertures throughout the nonwoven fabric Was.

<Making absorbent articles>
Peel off the top sheet from a commercially available sanitary napkin (trade name "Lorief Happiness Bare Skin Many Daytime Featherless" manufactured by Kao Corporation), and replace the top sheet with the multi-layer laminated non-woven fabric (MD30 cm x CD10) obtained above. .5 cm) was laminated to obtain an absorbent article for evaluation.

(Comparative Example 1)
<Manufacturing of multilayer non-woven fabric>
A multilayer nonwoven fabric of Comparative Example 1 was obtained in the same manner as in Example 1 except that the synthetic long fiber nonwoven fabric B was used as the second fiber layer. The resulting multilayer nonwoven has an opening of approximately 0.07~0.2mm ² (average 0.12 mm ^2), porosity is 2.4%, the open pores clearly formed over the entire non-woven fabric There were many places that were not done.

<Making absorbent articles>
An absorbent article for evaluation was obtained in the same manner as in Example 1 except that the multilayer non-woven fabric obtained in Comparative Example 1 was used.

(Comparative Example 2)
Using the cotton used in Example 1, a parallel card web having a ^{basis weight of 30 g / m 2 made of cotton fibers was produced.}
Water flow entanglement treatment (first water flow entanglement treatment) was performed on the card web. In the first water flow confounding process, the card web was placed on a 90-mesh plain weave support made of a monofilament having a wire diameter of 0.132 mm, and nozzles having orifices with a hole diameter of 0.12 mm provided at intervals of 0.6 mm were used. The columnar water flow of 2.0 MPa was sprayed once and the columnar water flow of 3.0 MPa was sprayed once from one surface of the card web. The transport speed of the support at this time was 4 m / min, and the distance between the nozzle and the card web was 10 mm.
Next, a water flow entanglement treatment (second water flow entanglement treatment) for forming an opening was carried out. In the second water flow entanglement treatment, the card web after the first water flow entanglement treatment is placed on a 12-mesh plain weave support made of a monofilament having a wire diameter of 1.2 mm, and the same nozzle as that used in the first water flow entanglement treatment is used. Was used to inject a 4.0 MPa columnar water flow once from the surface opposite to the surface of the card web injected during the first water flow confounding treatment. The transport speed of the support and the distance between the nozzle and the card web were the same as in the first water flow confounding treatment. The card web after the second water flow entanglement treatment was dried with a hot air dryer at 100 ° C. to obtain a nonwoven fabric of Comparative Example 2.

The breaking strength, breaking elongation and stress at 10% elongation of the nonwoven fabrics produced in Examples and Comparative Examples were measured as described above, and the results are shown in Table 2 below. Further, in the multilayer nonwoven fabrics produced in Example 1 and Comparative Example 1, the first fiber layer was removed by the following measurement sample preparation method, and the obtained second fiber layer was used to break the second fiber layer in the multilayer nonwoven fabric. The strength, elongation at break and stress at 5% elongation were measured as described above, and the results are shown in Table 3 below.
[Method for preparing a sample for measurement]
(1) A sample was obtained by cutting the multilayer non-woven fabric into 20 cm × 5 cm.
(2) Three cut samples and a stirrer were placed in a beaker, and 200 mL of 70% sulfuric acid was added.
(3) The first fiber layer was removed by stirring with a magnetic stirrer for 2 hours.
(4) After taking out the stirrer, sulfuric acid was discarded.
(5) The sample of the second fiber layer in the beaker was washed with running water.
(6) The sample of the second fiber layer after washing was spread on a petri dish and put in it, and dried in a dryer at 80 ° C. for 1 hour.
(7) The sample of the second fiber layer after drying was used as a measurement sample.

Using the absorbent articles for evaluation prepared in Examples and Comparative Examples, the liquid absorption time, diffusion length and liquid return amount were evaluated as described above. The results are shown in Table 4 below. Table 4 below also shows the basis weight and thickness of the multilayer nonwoven fabric measured as described above.

From the results in Table 4 above, the absorbent article of Example 1 has almost the same amount of liquid return as the absorbent article of Comparative Example 1, but a comparative example using a non-woven fabric made of 100% by mass of cotton fiber as a surface sheet. The amount of liquid returned was smaller than that of the absorbent article of 2. Further, the absorbent article of Example 1 had almost the same liquid absorption time as the absorbent article of Comparative Example 2 using a non-woven fabric made of 100% by mass of cotton fiber as a surface sheet, but the absorbent article of Comparative Example 1 was absorbed. The liquid absorption time was shorter than that of the article. In addition, the thickness is larger in Example 1, suggesting that the openings are clearly formed.

The non-woven fabric for absorbent articles of the present invention includes various absorbent articles such as sanitary napkins, infant paper diapers, adult paper diapers, paper diapers for animals such as mammals, panty liners (pantyliner sheets), and incontinence liners. Can be suitably used as a surface sheet of.

Claims (8)

A multilayer non-woven fabric containing a first fiber layer and a second fiber layer.
The first fiber layer is made of cotton fiber and has a basis weight of 5 to 30 g / m ² .
The second fiber layer is made of synthetic long fiber non-woven fabric and has a basis weight of 5 to 20 g / m ² .
The constituent fibers of the first fiber layer and the second fiber layer are three-dimensionally entangled and integrated.
The multilayer non-woven fabric has openings and
A non-woven fabric for absorbent articles, characterized in that the lateral breaking strength of the second fiber layer is 5.0 N / 5 cm or less. The nonwoven fabric for absorbent articles according to claim 1, wherein the stress at 5% elongation in the lateral direction of the second fiber layer is 0.5 N / 5 cm or less. The nonwoven fabric for absorbent articles according to claim 1 or 2, wherein the stress at 5% elongation in the longitudinal direction of the second fiber layer is 3.0 N / 5 cm or less. The nonwoven fabric for absorbent articles according to any one of claims 1 to 3, wherein the second fiber layer is a synthetic long fiber nonwoven fabric made of polyester fibers. A surface sheet for an absorbent article, which comprises the non-woven fabric for an absorbent article according to any one of claims 1 to 4, and has the first fiber layer as a skin-facing surface. An absorbent article comprising the surface sheet for the absorbent article according to claim 5. Consists cotton fibers, and basis weight is 5 to 30 g / m ^2, and the fibrous web of the first fibrous layer, a basis weight is 5 to 20 g / m ^2, and a synthetic filament nonwoven fabric made of a second fiber layer Laminate to form a laminate
By three-dimensionally entwining and integrating the constituent fibers of the first fiber layer and the second fiber layer in the laminated body, and by imparting an open hole structure to the laminated body.
It is a multilayer non-woven fabric containing a first fiber layer and a second fiber layer, and a non-woven fabric for absorbent articles having a perforated structure is obtained.
A method for producing a nonwoven fabric for absorbent articles, wherein the breaking strength of the second fiber layer in the lateral direction of the nonwoven fabric for absorbent articles is 5.0 N / 5 cm or less. The method for producing a nonwoven fabric for absorbent articles according to claim 7, wherein the synthetic long fiber nonwoven fabric to be the second fiber layer has a transverse breaking strength of 5.0 N / 5 cm or less in the step of forming the laminate.