TW202017545A - Nonwoven fabric for absorbent article, method of manufacturing same, surface sheet for absorbent article, and absorbent article - Google Patents

Abstract

The present invention relates to a nonwoven fabric for absorbent articles, the nonwoven fabric being a multilayer nonwoven fabric that has a first fiber layer and a second fiber layer, wherein the first fiber layer comprises cotton fibers and has a basis weight of 5 to 30 g/m2, the second fiber layer comprises a synthetic long fiber nonwoven fabric and has a basis weight of 5 to 20 g/m2, and the constituent fibers of the first fiber layer and the second fiber layer are integrated by being three-dimensionally interlaced. The multilayer nonwoven fabric has openings, and the second fiber layer has a lateral breaking strength of 5.0 N/5 cm or less. Thus, it is possible to provide a nonwoven fabric for absorbent articles, a surface sheet for absorbent articles, and an absorbent article including the surface sheet for absorbent articles, which have increased strength of the nonwoven fabric containing cotton fibers and has improved liquid absorbing properties.

Description

Nonwoven fabric for absorbent articles, method for manufacturing the same, surface sheet for absorbent articles, and absorbent articles

The present invention relates to a nonwoven fabric for absorbent articles used for absorbent articles such as sanitary napkins or paper diapers (including paper diapers for infants and adults), a method for manufacturing the same, a surface sheet for absorbent articles, and absorbency article.

Absorbent articles such as sanitary napkins or paper diapers are mainly composed of a surface sheet that contacts the wearer's skin, an absorbent body that absorbs liquid, and a leak-proof sheet that prevents liquid from leaking out of the absorbent article. In addition, for comfort when wearing, the surface sheet used for absorbent articles is required to have a soft and smooth touch, and to absorb fluids such as menstrual blood and other excretions such as blood, urine, or feces with fluidity. Excellent characteristics, etc.

In Patent Document 1, it is proposed to use a non-woven fabric composed of a surface layer and a non-woven fabric reinforcement layer for the skin surface layer of an absorbent product. The above-mentioned surface layer is composed of 30% to 100% cotton containing a basis weight of 5 to 50 g/m ² . Fiber builder. Prior Art Literature Patent Literature

Patent Literature 1: Japanese Special Publication No. 2016-529412

[Problems to be solved by the invention]

By including the non-woven fabric reinforcement layer in the non-woven fabric described in Patent Document 1, the strength of the non-woven fabric including cotton is improved, but the non-woven fabric reinforcement layer may hinder the higher liquid absorption characteristics of the cotton fiber.

In order to solve the above-mentioned conventional problems, the present invention provides a nonwoven fabric for absorbent articles that improves the strength of a nonwoven fabric containing cotton fibers and improves liquid absorption characteristics, a method for manufacturing the same, a surface sheet for absorbent articles, and an absorbent article. [Technical means to solve the problem]

The present invention relates to a nonwoven fabric for absorbent articles, characterized in that it is a multilayer nonwoven fabric including a first fiber layer and a second fiber layer, and the first fiber layer is composed of cotton fibers and has a basis weight of 5-30 g/m ^2. The second fiber layer is composed of synthetic long-fiber non-woven fabric with a basis weight of 5-20 g/m ^2. The constituent fibers of the first fiber layer and the second fiber layer are three-dimensionally intertwined and integrated with each other. The above-mentioned multilayer non-woven fabric has openings , The transverse breaking strength of the second fiber layer is 5.0 N/5 cm or less.

In the nonwoven fabric for absorbent articles described above, it is preferable that the stress at 5% elongation in the lateral direction of the second fiber layer is 0.5 N/5 cm or less. Preferably, the stress at 5% elongation in the longitudinal direction of the second fiber layer is 3.0 N/5 cm or less. Preferably, the second fiber layer is a synthetic long-fiber nonwoven fabric composed of polyester-based fibers.

The present invention also relates to a method for manufacturing nonwoven fabrics for absorbent articles, characterized in that the fiber web and the basis weight of the first fiber layer, which are composed of cotton fibers and have a basis weight of 5 to 30 g/m ² , are 5 to 20 The synthetic long-fiber non-woven fabric that becomes the second fiber layer of g/m ² is laminated to form a laminate, and the constituent fibers of the first fiber layer and the second fiber layer in the laminate are three-dimensionally intertwined and integrated, and the laminate The body is provided with an open cell structure, thereby obtaining a nonwoven fabric for absorbent articles having a multi-layer nonwoven fabric of the first fiber layer and the second fiber layer and having an open cell structure, and the transverse break of the second fiber layer in the nonwoven fabric for absorbent articles The strength is below 5.0 N/5 cm.

It is preferable that the breaking strength in the lateral direction of the synthetic long-fiber nonwoven fabric that becomes 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 absorbent articles, comprising the nonwoven fabric for absorbent articles described above, and having the first fiber layer as a skin facing surface.

The present invention also relates to an absorbent article comprising the above-mentioned surface sheet for absorbent articles. [Effect of invention]

The present invention can provide a nonwoven fabric for absorbent articles, a surface sheet for absorbent articles, and absorbent articles containing the same, which increase the strength of nonwoven fabrics containing cotton fibers and improve the liquid absorption characteristics. In addition, according to the method for manufacturing a nonwoven fabric for absorbent articles of the present invention, it is possible to obtain a nonwoven fabric for absorbent articles that improves the strength of a nonwoven fabric containing cotton fibers and improves liquid absorption characteristics.

The inventors have made intensive studies to solve the above problems. As a result, it was found that the second fiber layer composed of a synthetic long-fiber nonwoven fabric having a basis weight of 5 to 20 g/m ^{2 due} to the first fiber laminate composed of cotton fibers and having a basis weight of 5 to 30 g/m ² , Making the constituent fibers of the first fiber layer and the second fiber layer three-dimensionally intertwined and integrated to form a multi-layer non-woven fabric with openings, and the transverse breaking strength of the second fiber layer in the multi-layer non-woven fabric is 5.0 N/ Below 5 cm, it can increase the strength of non-woven fabrics containing cotton fibers and improve liquid absorption characteristics.

The nonwoven fabric for absorbent articles is a multilayer nonwoven fabric including a first fiber layer and a second fiber layer. The first fiber layer is composed of cotton fibers and has a basis weight of 5 to 30 g/m ² . By using cotton fibers to form the first fiber layer, the skin feels soft. From the viewpoint of improving the liquid leakage resistance of the nonwoven fabric for absorbent articles, that is, reducing the amount of liquid leakage, the basis weight of the first fiber layer is preferably 10 to 25 g/m ² , and more preferably 15 to 22 g /m ² .

The cotton fiber constituting the first fiber layer is not particularly limited, and for example, the fineness is preferably 0.5 to 6.0 dtex. From the viewpoint of smoothing the touch, 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 speed, the fineness is preferably 0.6 dtex or more, and more preferably 0.8 dtex or more. In addition, the fineness of cotton fiber can be calculated according to the method according to JIS L 1019 7.4.1 Micronaire.

The cotton fiber constituting the first fiber layer is not particularly limited, and considering the carding passability, the fiber length is preferably 1 to 100 mm. It is more preferably 10 to 80 mm, and still more preferably 15 to 60 mm. The fiber length need not all be the same. Natural fibers derived from plants, such as cotton fibers, are usually supplied in a form in which the fiber length is not fixed, but this form can be used.

As the first fiber layer, a fiber web can be used. Examples of the fiber web include carded webs such as parallel webs, semi-random webs, random webs, cross webs, and cross cross webs, and air-spun webs. Since the surface sheet for absorbent articles is required to have bulkiness, flexibility, and moderate porosity in such a way that there is a certain gap between fibers, the fiber web is preferably a carded web.

The second fiber layer is composed of a synthetic long fiber nonwoven fabric, and the constituent fibers of the first fiber layer and the second fiber layer are three-dimensionally intertwined and integrated. By laminating the first fiber layer composed of cotton fibers and the second fiber layer composed of synthetic long-fiber non-woven fabric to form a multi-layer non-woven fabric, the strength of the non-woven fabric for absorbent articles can be improved, and the amount of liquid re-infiltration can be reduced. In addition, since the long fiber nonwoven 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 intertwined with each other, there is essentially no synthetic fiber on the surface of the first fiber layer, and cotton fibers can be retained Unique soft skin touch. Here, "the surface of the first fiber layer is essentially free of synthetic fibers" means that the surface of the first fiber layer is completely free of synthetic fibers or even if there are some micro-synthetic fibers on the surface of the first fiber layer, it will not function or effect .

In the nonwoven fabric for absorbent articles described above, the breaking strength of the second fiber layer in the lateral direction (also referred to as the CD direction) is 5.0 N/5 cm or less. As a result, the intertwining of the constituent fibers of the first fiber layer and the second fiber layer is improved, the openings of the nonwoven fabric for absorbent articles become clear, the fluff is reduced, the texture is improved, and the feel becomes good. Preferably, the transverse 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, further preferably 3.0 N/5 cm or less, and still more preferably 2.5 N/5 cm or less, more preferably 2.0 N/5 cm or less, still more preferably 1.5 N/5 cm or less, and even more preferably 1.0 N/5 cm or less. From the viewpoint of improving the strength of the nonwoven fabric for absorbent articles, the transverse 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 further preferably 0.5 N /5 cm or more.

In the nonwoven fabric for absorbent articles described above, the second fiber layer is not particularly limited, and from the viewpoint of further improving the mutuality of the constituent fibers of the first fiber layer and the second fiber layer, the longitudinal direction (also called MD Direction) The breaking strength 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, and even more preferably 4.0 N/5 cm or less, and even more preferably It is 2.0 N/5 cm or less, and more preferably 1.5 N/5 cm or less. From the viewpoint of improving the strength of the nonwoven fabric for absorbent articles, the breaking strength in the longitudinal direction of the second fiber layer is preferably 0.3 N/5 cm or more, more preferably 0.5 N/5 cm or more, and further preferably 0.7 N /5 cm or more.

In the nonwoven fabric for absorbent articles described above, the second fiber layer is not particularly limited, and from the viewpoint of further improving the intertwining of the constituent fibers and providing clearer pores, the elongation at break in the lateral direction is preferably 5 to 100%, more preferably 10 to 80%, and still more preferably 20 to 70%. In addition, in the nonwoven fabric for absorbent articles, the second fiber layer is not particularly limited, and from the viewpoint of further improving the intertwining of the constituent fibers and providing clearer openings, the longitudinal elongation at break is preferably 20 to 100%, more preferably 30 to 80%, and still more preferably 35 to 70%.

In the nonwoven fabric for absorbent articles described above, the second fiber layer is not particularly limited, and from the viewpoint of further improving the cross-linking properties of the constituent fibers and providing clearer openings, the stress at 5% elongation in the lateral direction is preferably 0.01 to 1.0 N/5 cm, more preferably 0.02 to 0.9 N/5 cm, still more preferably 0.03 to 0.8 N/5 cm, still more preferably 0.03 to 0.2 N/5 cm. In the nonwoven fabric for absorbent articles described above, the second fiber layer is not particularly limited. From the viewpoint of further improving the cross-linking properties of the constituent fibers and providing clearer openings, the stress at 5% elongation in the longitudinal direction is preferably 0.03 to 10 N/5 cm, more preferably 0.05 to 8.0 N/5 cm, still more preferably 0.07 to 5.0 N/5 cm, still more preferably 0.07 to 1.0 N/5 cm.

The basis weight of the above synthetic long-fiber nonwoven fabric (second fiber layer) is 5 to 20 g/m ² , and it is preferable from the viewpoint of further improving the intertwinability of constituent fibers and giving clearer openings or cost. It is 7-18 g/m ² , more preferably 8-15 g/m ² .

The synthetic long-fiber nonwoven fabric is not particularly limited, and examples thereof include spunbond nonwoven fabric and melt-blown nonwoven fabric. From the viewpoints of cost, inter-complexity of constituent fibers, clarity of openings, strength of multilayer non-woven fabric, and high liquid absorption speed, spun-bonded non-woven fabric is preferable.

The synthetic long fiber nonwoven fabric is not particularly limited as long as it is a nonwoven fabric composed of synthetic long fibers. From the viewpoint of reducing the amount of liquid re-infiltration, the synthetic long fibers are preferably hydrophobic fibers. The hydrophobic fiber may be, for example, a fiber having a regular moisture content of 5.0% or less, more preferably 2.0% or less, and further preferably 1.0% or less. The official moisture content is shown in JIS L0105 (2006). When the public moisture content is unknown, the value calculated according to the following formula is used as the public moisture content. Common moisture content (%) = [(W－W')/W']×100 Here, W refers to the mass (g) of the fiber in an environment with a temperature of 20° C. and a humidity of 65% RH, and W′ refers to the mass (g) of the fiber when it is absolutely dry. Furthermore, the quality of the fiber in an environment with a temperature of 20°C and a humidity of 65%RH refers to the quality when the fiber is placed in an environment with a temperature of 20°C and a humidity of 65%RH to become a certain quality, and the quality of the fiber when it is absolutely dry refers to the The quality when the fiber is placed in a dryer set at 105°C to become a certain quality.

The hydrophobic fiber is not particularly limited as long as it has a nominal moisture content of 5.0% or less, and examples thereof include polyester fibers, polyolefin fibers, polyamide fibers, acrylic fibers, and vinyl chloride fibers. . As the polyester fiber, for example, selected from polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid, poly Fibers composed of more than one type of polyester resin in butylene succinate and its copolymers. As the polyolefin-based fiber, for example, a fiber composed of one or more polyolefin-based resins selected from polypropylene, polyethylene, polybutene-1, and ethylene-propylene copolymer can be used. As the polyamide fiber, for example, a fiber composed of polyamide resin like nylon 6 or nylon 66 can be used. The above synthetic long fibers may be single fibers or composite fibers. From the standpoint of further reducing the amount of liquid repermeation, polyester-based fibers or polyolefin-based fibers are preferred, and from the standpoint of the intertwinability of constituent fibers, polyester-based fibers are particularly preferred.

In the above-mentioned synthetic long fiber nonwoven fabric, the fineness of the synthetic long fiber is not particularly limited, and for example, preferably 0.6 to 5.0 dtex. From the viewpoint of the uniformity of the basis weight of the synthetic long-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 speed, the fineness is preferably 0.6 dtex or more, and more preferably 0.8 dtex or more.

The nonwoven fabric for absorbent articles is not particularly limited. For example, the laminate can be formed by laminating a fiber web composed of 100% by mass of cotton fibers as the first fiber layer and a synthetic long fiber nonwoven fabric as the second fiber layer. The constituent fibers of the first fiber layer and the second fiber layer are three-dimensionally intertwined and integrated with each other, and are produced by giving an opening structure to the laminate. Specifically, it is possible to integrate the constituent fibers of the first fiber layer and the second fiber layer by three-dimensionally entanglement with each other by subjecting the laminate to water flow entanglement, and to give the laminate a hole structure.

The transverse breaking strength of the synthetic long-fiber nonwoven fabric used as the raw material of the second fiber layer is preferably 5.0 N/5 cm or less, more preferably 4.0 N/5 cm or less, and further preferably 3.5 N/5 cm or less, Furthermore, it is more preferably 3.0 N/5 cm or less, and still more preferably 2.5 N/5 cm or less. As a result, the intertwining of the constituent fibers of the first fiber layer and the second fiber layer is improved, the openings of the nonwoven fabric for absorbent articles become clear, the fluff is reduced, the texture is improved, and the feel becomes good. From the viewpoint of improving the strength of the nonwoven fabric for absorbent articles, the transverse breaking strength of the synthetic long fiber nonwoven fabric used as the raw material of the second fiber layer is preferably 0.5 N/5 cm or more, and more preferably 1.0 N/5 cm or more, and more preferably 1.3 N/5 cm or more.

The longitudinal breaking strength of the synthetic long fiber nonwoven fabric used as the raw material of the second fiber layer is preferably 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 even more preferably 10 N/5 cm or less. As a result, the intertwining of the constituent fibers of the first fiber layer and the second fiber layer is improved, the openings of the nonwoven fabric for absorbent articles become clear, the fluff is reduced, the texture is improved, and the feel becomes good. From the viewpoint of improving the strength of the nonwoven fabric for absorbent articles, the longitudinal breaking strength of the synthetic long fiber nonwoven fabric used as the raw material of the second fiber layer is preferably 2.0 N/5 cm or more, more preferably 3.0 N/5 cm or more, and more preferably 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. For example, from the viewpoint of further improving the intertwinability of constituent fibers and providing clearer openings, the transverse elongation at break is preferably 3 to 70%, more preferably 5 to 60%, still more preferably 7 to 50%, still more preferably 7 to 30%. In addition, the synthetic long-fiber nonwoven fabric used as the raw material of the second fiber layer is not particularly limited. For example, in terms of further improving the intertwining of constituent fibers and providing clearer openings, the elongation at break in the longitudinal direction is It is preferably 5 to 40%, more preferably 7 to 30%, and still more preferably 8 to 20%.

The synthetic long-fiber non-woven fabric used as the raw material of the second fiber layer is not particularly limited. For example, from the viewpoint of further improving the intertwining of the constituent fibers and providing clearer openings, the stress at 5% elongation in the lateral direction is It is preferably 0.1 to 5.0 N/5 cm, more preferably 0.5 to 4.0 N/5 cm, and still more preferably 0.7 to 3.0 N/5 cm. The synthetic long-fiber nonwoven fabric used as the raw material of the second fiber layer is not particularly limited, and from the viewpoint of further improving the inter-complexity of the constituent fibers and giving clearer openings, the stress at 5% elongation in the longitudinal direction is preferably 1.5 to 8.0 N/5 cm, more preferably 2.0 to 7.0 N/5 cm, and still more preferably 3.0 to 6.0 N/5 cm.

Regarding the water flow cross-over treatment, the laminate can be placed on the support and sprayed with water on one or both sides of the laminate. The shape of the above-mentioned support is not particularly limited, as long as a conventionally known support is used, for example, a warp yarn having a wire diameter of 0.05 mm to 1.5 mm, a weft yarn having a wire diameter of 0.05 mm to 1.5 mm, and a mesh number of 5 ~110 mesh plain weave mesh. The nozzle with an orifice with an aperture of 0.05 to 0.5 mm can be provided at intervals of 0.5 to 1.5 mm, and the water flow of 1.0 to 10.0 MPa water pressure can be sprayed on the single side or both sides of the laminated body respectively for 1 to 4 times. If the water pressure is less than 1.0 MPa, the intertwining of fibers becomes insufficient, and there may be cases where fluff is likely to fall out of the obtained nonwoven fabric. If the water pressure exceeds 10.0 MPa, the intertwining of the fibers becomes too strong and the touch of the nonwoven fabric for absorbent articles may be reduced or the intertwining of the cotton fibers is excessively carried out, which changes the amount of cotton fibers in the synthetic long fiber nonwoven fabric There is a risk that the amount of liquid leakage will increase. The water pressure is more preferably 2.0 to 9.0 MPa, further preferably 2.0 to 7.0 MPa, and still more preferably 2.0 to 6.0 MPa. The distance between the nozzle and the laminate can be, for example, 5-30 mm, or 7-20 mm.

Specifically, first, the laminate is placed on a support, and a water flow with 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 laminate to thereby make the first fiber layer and The constituent fibers of the second fiber layer are three-dimensionally intertwined and integrated. At this time, as the support, it is preferable to use a plain weave net having a warp yarn 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 mesh. Then, the laminate is placed on a coarse mesh plain weave net, for example, a warp yarn with a wire diameter of 0.5 to 1.5 mm, a weft yarn with a wire diameter of 0.5 to 1.5 mm, and a mesh number of 5 to 60 mesh plain weave. On the surface of the second fiber layer, spray a water stream with a water pressure of 1.0 to 10.0 MPa for 1 to 4 times to form an opening.

Then, the multi-layer non-woven fabric obtained by intersecting the water stream is dried. The drying treatment can be performed using a hot air dryer, for example. The drying temperature is preferably such as a temperature that does not generate heat adhering to the fiber.

The nonwoven fabric for absorbent articles is not particularly limited. For example, from the viewpoint of having clear pores throughout the entire nonwoven fabric, the aperture ratio is preferably 5% or more, more preferably 10% or more, and further preferably 15% the above. In addition, the nonwoven fabric for absorbent articles is not particularly limited. For example, from the viewpoint of having clear pores throughout the entire nonwoven fabric, the aperture area is preferably 0.5 to 3.5 mm ² , and more preferably 0.7 to 3.0 mm ² .

The nonwoven fabric for absorbent articles is not particularly limited. For example, from the viewpoint of strength and touch, the breaking strength in the lateral direction is preferably 3.0 to 30 N/5 cm, more preferably 5.0 to 25 N/5 cm, Furthermore, it is more preferably 7.0 to 20 N/5 cm. In addition, the breaking strength in the longitudinal direction is preferably 10 to 60 N/5 cm, more preferably 15 to 50 N/5 cm, and still more preferably 20 to 40 N/5 cm.

The nonwoven fabric for absorbent articles is not particularly limited. For example, from the viewpoint of workability such as cutting, the elongation at break in the transverse direction is preferably 50 to 200%, more preferably 60 to 180%, and further preferably 70～150%. The nonwoven fabric for absorbent articles is not particularly limited. From the viewpoint of workability such as cutting, the elongation at break in the longitudinal direction is preferably 10 to 100%, more preferably 15 to 80%, and further preferably 20～60%.

The nonwoven fabric for absorbent articles is not particularly limited. For example, from the viewpoint of strength and touch, the stress at 10% elongation in the transverse direction is preferably 0.3 to 2.5 N/5 cm, more preferably 0.4 to 2.0 N/ 5 cm, further preferably 0.5 to 1.5 N/5 cm, still more preferably 0.6 to 1.2 N/5 cm. The nonwoven fabric for absorbent articles is not particularly limited. For example, from the viewpoint of strength and touch, the stress at 10% elongation in the longitudinal direction is preferably 2.0 to 25 N/5 cm, more preferably 3.0 to 20 N/ 5 cm, further preferably 4.0 to 10 N/5 cm, still more preferably 5.0 to 9.0 N/5 cm.

The nonwoven fabric for absorbent articles described above can be used as a surface sheet for absorbent articles. In the above-mentioned surface sheet for absorbent articles, the first fiber layer directly contacts the skin of the wearer wearing the absorbent article. By contacting the skin with the first fiber layer composed of cotton fibers, the user of the absorbent article can be given a comfortable feeling of use.

The surface sheet for absorbent articles can be preferably used as sanitary napkins, paper diapers for children, paper diapers for adults, paper diapers for animals represented by mammals, sanitary pads (woven sheets), incontinence pads, etc. Surface sheet of various absorbent articles.

The absorbent article of the present invention is not particularly limited as long as it contains the above-mentioned surface sheet for absorbent articles. For example, sanitary napkins, paper diapers for infants, paper diapers for adults, paper diapers for animals represented by mammals, sanitary pads (woven sheets), incontinence pads, etc. may be mentioned. Examples

Hereinafter, the present invention will be described more specifically by examples, but the present invention is not limited to these examples.

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

(base weigh) Measured according to JIS L 1913 (mass per unit area).

(Thickness) The thickness is measured using a thickness measuring instrument (made by Daiei Seiki Instruments Co., Ltd., trade name "THICKNESSGAUGEJ, sample "CR-60A") with a load of 2.94 cN per 1 cm ² sample.

(Breaking strength, elongation at break, stress at 5% elongation, stress at 10% elongation) In accordance with JIS L 1913 (2010) 6.3, using a constant-speed tension type tensile testing machine, the tensile test was carried out under the conditions of a sample piece width of 5 cm, a clamping interval of 10 cin, and a tensile speed of 30±2 cm/min. Determine the load value (tensile strength (breaking strength)), elongation (breaking elongation), and 5% elongation stress (or 10% elongation stress) at the time of cutting. The tensile test was performed with the longitudinal direction (MD direction) and the lateral direction (CD direction) of the nonwoven fabric as the tensile direction. The evaluation results are expressed as the average of the measured values of the three samples.

(Aperture area, aperture ratio) Use a microscope (manufactured by 3R Solution, model "3R-MSUSB401") to take a 60-fold magnified photo of the surface of the nonwoven fabric viewed from the first fiber layer side, and use the image analysis processing software "Image" (free software). The opening part of the image and other parts are binarized, and the ratio of the total area of the opening part to the entire area of the nonwoven fabric is obtained as the opening ratio. In addition, the photo is taken of two randomly selected two parts (1 cm × 1 cm) of the nonwoven fabric of the sample, and the average value of these is taken as the porosity. The area of the opening is the area of each of the openings in the two randomly selected parts, and the area of each opening is measured, and the average value is calculated as the area of the opening.

(Liquid absorption time) In the absorbent article used for evaluation, place the plate into the tube on the sample nonwoven (height 75 mm, inner diameter of the upper part of the tube 25 mm, inner diameter of the lower part of the tube 10 mm, wall thickness) 5 mm in two-stage cylindrical shape), inject the 5.0 mm cc of artificial menstrual blood (temperature 37° C., viscosity 8 MPa·s) into the injection cylinder of the annotated plate. Measure the time required until no liquid can be seen on the surface of the nonwoven fabric as the liquid absorption time (seconds). Furthermore, 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) ) 1.04 mass%, blue powder 0.06 mass%. In addition, after the measurement of the liquid absorption time, 15 minutes later, another 5.0 cc of artificial menstrual blood (temperature 37° C., viscosity 8 MPa·s) was injected, and the second liquid absorption time (second) was measured.

(Diffusion length) In the first measurement of the liquid absorption time, 5 minutes after the injection of artificial menstrual blood, the length of the portion of the test sample in the MD direction in which the artificial menstrual blood is absorbed is calculated as the diffusion length. In addition, when measuring the liquid suction time for the second time, the diffusion length was measured 5 minutes after the injection of artificial menstrual blood in the same manner as the first time.

(Liquid re-infiltration volume) In the absorbent article for evaluation, artificial menstrual blood was injected in the same manner as the first measurement of the liquid absorption time, and 10 sheets were placed on the non-woven fabric that became the top sheet (surface sheet) 10 minutes after the injection. Filter paper (manufactured by Toyo Filter Paper Co., Ltd., trade name ADVANTEC (registered trademark) No. 2, 10 cm×10 cm), and a weight of 1 kg (shape: square, 10 cm×10 cm) is placed on the filter paper. After 20 seconds from placing the weight, remove the filter paper, measure the mass of the filter paper that has absorbed the menstrual blood, subtract the mass of the filter paper before placing it on the non-woven fabric, and calculate the first liquid re-infiltration (g). Furthermore, in the absorbent article for evaluation, artificial menstrual blood was injected in the same manner as the second measurement of the liquid absorption time, and 10 minutes after the injection, the second time was calculated using filter paper in the same manner as the first time The amount of liquid re-infiltration (g).

In addition, when measuring the liquid absorption time, the diffusion length, and the amount of liquid repermeation, two samples were prepared for the nonwoven fabrics of the examples and comparative examples. The average value of the liquid absorption time, diffusion length, and liquid resorption amount measured for each of the two samples was used as the liquid absorption time, diffusion length, and liquid resorption amount of the nonwoven fabrics of each example and comparative example.

As a synthetic long-fiber nonwoven fabric, the following is prepared. Synthetic long-fiber non-woven fabric A: Spunbond non-woven fabric with a basis weight of 10 g/m ² composed of polyethylene terephthalate long fibers with a fineness of 1.6 dtex (fiber diameter 12.2 μm) (nominal moisture content: 0.4%). Synthetic long-fiber non-woven fabric B: Spunbond non-woven fabric with a basis weight of 10 g/m ² composed of polypropylene filaments with a fineness of 2.3 dtex (fiber diameter of 18.0 μm) (common moisture content: 0.0%). 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.

[Table 1]

(Example 1) <Preparation of multi-layer 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 Maruzan Industry Co., Ltd.), a basis weight 20 made of cotton fibers was produced A g/m ² parallel card web is used as the first fiber layer. Synthetic long-fiber non-woven fabric A was used as the second fiber layer. The first fiber layer is stacked on the second fiber layer, and the obtained laminate is subjected to water flow interleaving treatment (first water flow interleaving treatment). The first water flow treatment is to place the laminate on a 90-mesh plain weave support composed of monofilaments with a diameter of 0.132 mm. Use a nozzle with an aperture of 0.12 mm at 0.6 mm intervals from the first fiber The surface of the layer was sprayed once with a columnar water flow of 2.0 MPa and once with a columnar water flow of 3.0 MPa. At this time, the transfer speed of the support is 4 m/min, and the distance between the nozzle and the laminate is 10 mm. Then, a water flow cross-over treatment (second water flow cross-over treatment) for forming openings is performed. The second water flow crossover treatment is to place the laminated body after the first water flow crossover treatment on a 12-mesh plain weave support composed of a monofilament with a wire diameter of 1.2 mm, and the use is the same as the user in the first water flow crossover treatment The nozzle is sprayed once with a 4.0 MPa columnar water flow from the surface of the second fiber layer. The transfer speed of the support and the distance between the nozzle and the laminate are the same as the first water flow cross-over treatment. The laminated body after the second water flow intersecting treatment was dried with a hot air dryer at 100°C to obtain the multilayer nonwoven fabric of Example 1. The obtained multi-layer non-woven fabric has openings of about 0.5-2.0 mm ² (average 1.2 mm ² ), the opening ratio is 24%, and there are roughly clear openings throughout the entire non-woven fabric.

<Production of absorbent articles> From commercially available physiological sanitary napkins (trade name "Laurier F series bliss muscular multi-day without wings" manufactured by Kao Co., Ltd.), peel off the top sheet, replace the top sheet, and laminate the multi-layer laminated nonwoven fabric obtained above (MD30 cm×CD10.5 cm), an absorbent article for evaluation was obtained.

(Comparative Example 1) <Preparation of multilayer nonwoven fabric> The multilayer nonwoven fabric of Comparative Example 1 was obtained in the same manner as in Example 1 except that synthetic long fiber nonwoven fabric B was used as the second fiber layer. The obtained multilayer non-woven fabric had openings of about 0.07-0.2 mm ² (average 0.12 mm ² ), and the opening ratio was 2.4%, and there were many unclearly formed openings throughout the entire non-woven fabric.

<Production of absorbent articles> Except for using the multilayer nonwoven fabric obtained in Comparative Example 1, an absorbent article for evaluation was obtained in the same manner as in Example 1.

(Comparative Example 2) Using the cotton used in Example 1, a parallel carded web having a basis weight of 30 g/m ² made of cotton fibers was produced. The carding net is subjected to water flow interleaving treatment (the first water flow interleaving treatment). The first water flow treatment is to place the card web on a 90 mesh plain weave support made of monofilaments with a diameter of 0.132 mm. Use a nozzle with an aperture of 0.12 mm at 0.6 mm intervals to self-carding One side of the net was sprayed with a columnar water flow of 2.0 MPa and a columnar water flow of 3.0 MPa once. At this time, the conveying speed of the support is 4 m/min, and the distance between the nozzle and the card web is 10 mm. Then, a water flow cross-over treatment (second water flow cross-over treatment) for forming openings is performed. The second water flow treatment is to place the card web after the first water flow treatment on a 12-mesh plain weave support composed of a monofilament with a diameter of 1.2 mm, and use it in the first water flow treatment. The same nozzle was sprayed once with a 4.0 MPa columnar water flow from the surface opposite to the surface of the card web that was sprayed during the first water flow. The conveying speed of the support and the distance between the nozzle and the card web are the same as the first water flow cross-over treatment. The card web after the second water flow entanglement treatment was dried with a hot air dryer at 100°C to obtain the nonwoven fabric of Comparative Example 2.

The breaking strength, elongation at break, 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. In addition, in the multilayer nonwoven fabric 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 measure the multilayer nonwoven fabric as described above The breaking strength, breaking elongation, and stress at 5% elongation of the second fiber layer in the table are shown in Table 3 below. [Method of making sample for measurement] (1) The multilayer non-woven fabric was cut into 20 cm × 5 cm to obtain a sample. (2) Put 3 cut samples and stir bar in the beaker, and put 200 mL of 70% sulfuric acid. (3) Stir for 2 hours with a magnetic stirrer to remove the first fiber layer. (4) After taking out the stir bar, discard the sulfuric acid. (5) Wash the sample of the second fiber layer in the beaker with running water. (6) The sample of the second fiber layer after washing is developed into a petri dish, and dried for 1 hour using a dryer at 80°C. (7) The sample of the second fiber layer after drying was used as a sample for measurement.

Using the absorbent articles prepared in the Examples and Comparative Examples, the liquid absorption time, the diffusion length, and the amount of liquid re-infiltration were evaluated as described above. The results are shown in Table 4 below. In Table 4 below, the basis weight and thickness of the multilayer non-woven fabric measured as described above are also shown.

[Table 2]

[table 3]

[Table 4]

According to the results in Table 4 above, the amount of liquid repermeation of the absorbent article of Example 1 is approximately equal to that of the absorbent article of Comparative Example 1, but the amount of liquid repermeation is less than that of using a non-woven fabric composed of 100% by mass of cotton fiber as the surface sheet The absorbent article of Comparative Example 2. In addition, the absorption time of the absorbent article of Example 1 is almost the same as that of Comparative Example 2 using a non-woven fabric composed of 100% by mass of cotton fibers as a surface sheet, but the absorption time is shorter than that of Comparative Example 1. Sex goods. In addition, the thickness of Example 1 is larger, indicating that the opening is clearly formed. Industrial availability

The nonwoven fabric for absorbent articles of the present invention can be preferably used as a sanitary napkin, a paper diaper for infants, a paper diaper for adults, a paper diaper for animals represented by mammals, a sanitary pad (woven sheet), and an incontinence pad The surface sheet of various absorbent articles.

no

no

Claims (9)

A nonwoven fabric for absorbent articles, which is a multilayer nonwoven fabric including a first fiber layer and a second fiber layer, the first fiber layer is composed of cotton fibers and has a basis weight of 5-30 g/m ² , and the second fiber layer is composed of The growing fiber nonwoven fabric 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 intertwined and integrated with each other. The above-mentioned multilayer nonwoven fabric has openings and the second fiber layer has a transverse direction The breaking strength 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 claim 1 or 2, wherein the second fiber layer is a synthetic long fiber nonwoven fabric composed of polyester-based fibers. The nonwoven fabric for absorbent articles according to claim 3, wherein the second fiber layer is a synthetic long fiber nonwoven fabric composed of polyester fibers. A surface sheet for absorbent articles, comprising the nonwoven fabric for absorbent articles according to any one of claims 1 to 5, and using the first fiber layer as a skin-facing surface. An absorbent article comprising the surface sheet for absorbent articles according to claim 6. A method for manufacturing nonwoven fabrics for absorbent articles, characterized in that the fiber web and the basis weight of the first fiber layer made of cotton fibers and having a basis weight of 5 to 30 g/m ² are 5 to 20 g/ The composite long fiber non-woven fabric which becomes the second fiber layer of m ² is laminated to form a laminate, and the constituent fibers of the first fiber layer and the second fiber layer in the laminate are three-dimensionally intertwined and integrated, and the laminate is given An open-cell structure, a nonwoven fabric for absorbent articles having a multi-layer nonwoven fabric including the first fiber layer and the second fiber layer and having an open-cell structure, and the transverse breaking strength of the second fiber layer in the nonwoven fabric for absorbent articles is 5.0 Below N/5 cm. The method for manufacturing a nonwoven fabric for absorbent articles according to claim 8, wherein the transverse breaking strength of the synthetic long fiber nonwoven fabric which becomes the second fiber layer in the step of forming the laminate is 5.0 N/5 cm or less .