JP2021159314A - Absorbent article nonwoven fabric and absorbent article comprising the same - Google Patents

Abstract

To provide an absorbent article nonwoven fabric comprising preferable tactile and reducing liquid return, and an absorbent article comprising the same.SOLUTION: An absorbent article nonwoven fabric 1 of the present invention comprises: a first fiber layer 11 contacting a skin; and a second fiber layer 12 adjacent to the first fiber layer. The first fiber layer 11 includes by 50 mass% or greater, a first core sheath type composite fiber, the second fiber layer 12 includes by 50 mass% or greater, a second core sheath type composite fiber, the first core sheath type composite fiber has fineness of 0.5 dtex or greater and 2.1 dtex or smaller, the second core sheath type composite fiber has fineness of 2.2 dtex or greater and 7.0 dtex or smaller, and on a surface of the first core sheath type composite fiber, a first fiber processing agent is adhered. On a surface of the second core sheath type composite fiber, a second fiber processing agent is adhered. At least parts of the first and second core sheath type composite fibers are thermally adhered by sheath components of the first and second core sheath type composite fibers.SELECTED DRAWING: Figure 1

Description

The present invention relates to a non-woven fabric for an absorbent article used for an absorbent article such as a sanitary napkin or a paper diaper, and an absorbent article containing the same. More specifically, the present invention relates to a non-woven fabric for an absorbent article having a multi-layer structure, and an absorbent article containing the same.

Absorbent articles such as sanitary napkins and disposable diapers (including disposable diapers for infants and adults) mainly include surface sheets that come into contact with the wearer's skin, absorbents that absorb liquid, and liquid leaks to the outside. It is composed of a leak-proof sheet that does not allow it. A non-woven fabric is preferably used as the surface sheet used for the absorbent article. For example, Patent Document 1 has a first layer having a fiber diameter of 11 to 18 μm and a second layer having a fiber diameter of 19 to 31 μm arranged adjacent to the first layer. Top sheets used for absorbent articles made of non-woven fabric have been proposed. Patent Document 2 comprises a laminated non-woven fabric having an upper layer arranged on the skin side and a lower layer arranged on the absorber side, and the hydrophilicity of the lower layer is higher or almost equal to that of the upper layer before liquid permeation. After the liquid permeates, a surface sheet of an absorbent article having a higher hydrophilicity of the upper layer than that of the lower layer has been proposed. According to Patent Document 3, when 90 g of artificial urine is passed under a non-pressurized condition at a rate of 5.0 g / sec, the first region and the second region in which the hydrophilicity of the constituent fibers are different from each other are in the thickness direction. An absorbent article has been proposed in which a non-woven fabric that is formed along the line is arranged so as to face the wearer's skin.

Japanese Unexamined Patent Publication No. 2004-166831 Japanese Unexamined Patent Publication No. 2005-324010 JP-A-2017-42607

However, in the case of the non-woven fabric described in Patent Document 1, the liquid return may be large depending on the fiber treatment agent adhering to the surface of the constituent fibers of the non-woven fabric. In the case of the non-woven fabrics described in Patent Documents 2 and 3, there is a problem that the tactile sensation is inferior.

In order to solve the above problems, the present invention provides a non-woven fabric for an absorbent article having a good tactile sensation and reduced liquid return, and an absorbent article containing the same.

The present invention is a non-woven fabric for an absorbent article including a first fiber layer in contact with the skin and a second fiber layer adjacent to the first fiber layer, and the core component of the first fiber layer is polyester. A first containing 60% by mass or more of a resin, having a sheath component containing 60% by mass or more of a thermoplastic resin having a melting point of 50 ° C. or more lower than the melting point of the polyester resin, and having a single fiber fineness of 0.5 dtex or more and 2.1 dtex or less. It is a fiber layer containing 50% by mass or more of a 1-core sheath type composite fiber, and the second fiber layer has a core component of 60% by mass or more of a polyester resin and a sheath component having a melting point of 50 ° C. or more lower than the melting point of the polyester resin. It is a fiber layer containing 60% by mass or more of a thermoplastic resin having a single fiber fineness of 2.2 dtex or more and 7.0 dtex or less, and 50% by mass or more of a second core-sheath type composite fiber, and is a first core-sheath type composite. A first fiber treatment agent is attached to the surface of the fiber, a second fiber treatment agent is attached to the surface of the second core-sheath type composite fiber, and the first fiber treatment agent is an alkyl chain. It contains a component A composed of a linear alkyl phosphate ester salt having 6 or more and 22 or less carbon atoms, and the component A has at least one alkyl group having 16 carbon atoms and at least one alkyl group having 16 carbon atoms. Contains 18 component a2 and at least one alkyl group having 10 or less carbon atoms, and the mass ratio a1 / a2 between component a1 and component a2 is 1.0 or more and 3.4 or less, and component a1 and The mass ratio a3 / (a1 + a2) of the component a3 to the total mass of the component a2 is 3.0 or less, and the total content of the component a1 and the component a2 in the first fiber treatment agent is 7% by mass or more and 12% by mass or less. The second fiber treatment agent is a straight chain having a component B composed of a polyoxyalkylene branched alkyl ether phosphoric acid ester salt having 6 or more and 9 or less carbon atoms in the alkyl chain and 6 or more and 22 or less carbon atoms in the alkyl chain. The content of the component B in the second fiber treatment agent is 30% by mass or more and 35% by mass or less, and the content of the component C is 13% by mass or more and 23% by mass or less. Yes, at least a part of the first core-sheath type composite fiber and the second core-sheath type composite fiber is thermally adhered by the sheath component of the first core-sheath type composite fiber and the second core-sheath type composite fiber. The present invention relates to a non-woven fabric for an absorbent article, which is characterized by being present.

The present invention also relates to an absorbent article comprising the above-mentioned non-woven fabric for an absorbent article as a surface sheet and in which the first fiber layer is arranged so as to come into contact with the skin.

The present invention can provide a non-woven fabric for an absorbent article having a good tactile sensation and reduced liquid return, and an absorbent article containing the same.

FIG. 1 is a schematic cross-sectional view of a non-woven fabric for an absorbent article according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a fiber cross section of a core-sheath type composite fiber having a concentric circular structure. 3A to 3D are schematic views showing the crimped form of the core-sheath type composite fiber.

As a result of diligent studies to solve the above problems, the inventors of the present invention have made an absorbent article containing a first fiber layer in contact with the skin and a second fiber layer adjacent to the first fiber layer. In the non-woven fabric for use, the first fiber layer contains a predetermined core component and sheath component, the single fiber fineness is 0.5 dtex or more and 2.1 dtex or less, and the first fiber treatment agent is attached to the surface of the fiber. The core-sheath type composite fiber is contained in an amount of 50% by mass or more, the second fiber layer contains a predetermined core component and a sheath component, the single fiber fineness is 2.2 dtex or more and 7.0 dtex or less, and the second fiber is on the surface of the fiber. The second core-sheath type composite fiber to which the treatment agent is attached is contained in an amount of 50% by mass or more, and the first fiber treatment agent is composed of a linear alkyl phosphate ester salt having 6 or more and 22 or less carbon atoms in the alkyl chain. Containing component A, component A has at least one alkyl group having 16 carbon atoms, at least one alkyl group having 16 carbon atoms, and at least one alkyl group having 18 carbon atoms, and at least one alkyl group having 10 or less carbon atoms. The mass ratio a1 / a2 of the component a1 and the component a2 is 1.0 or more and 3.4 or less, and the mass ratio a3 / (a1 + a2) of the component a3 to the total mass of the component a1 and the component a2 is 3. Using a fiber treatment agent having a total content of .0 or less and a total content of component a1 and component a2 of 7% by mass or more and 12% by mass or less, the alkyl chain has 6 or more and 9 or less carbon atoms as the second fiber treatment agent. It contains a component B composed of a polyoxyalkylene branched alkyl ether phosphoric acid ester salt and a component C composed of a linear alkyl phosphate ester salt having 6 or more and 22 or less carbon atoms in the alkyl chain, and the content of the component B is It was found that by using a fiber treatment agent having a content of 30% by mass or more and 35% by mass or less and a content of component C of 13% by mass or more and 23% by mass or less, the tactile sensation is good and the liquid return is reduced. ..

The non-woven fabric for absorbent articles of the present invention includes a first fiber layer that comes into contact with the skin and a second fiber layer that is adjacent to the first fiber layer. FIG. 1 is a schematic cross-sectional view of a non-woven fabric for an absorbent article according to an embodiment of the present invention. As shown in FIG. 1, the non-woven fabric 1 for absorbent articles is composed of a first fiber layer 11 and a second fiber layer 12 adjacent to the first fiber layer 11.

(First fiber layer)
The first fiber layer contains 60% by mass or more of a polyester resin as a core component, 60% by mass or more of a thermoplastic resin having a sheath component having a melting point of 50 ° C. or more lower than the melting point of the polyester resin, and has a single fiber fineness of 0. It is a fiber layer having 5 dtex or more and 2.1 dtex or less, and containing 50% by mass or more of the first core-sheath type composite fiber in which the first fiber treatment agent is attached to the fiber surface. From the viewpoint of excellent tactile sensation and liquid absorption characteristics, the first fiber layer preferably contains the first core-sheath type composite fiber in an amount of 60% by mass or more, more preferably 70% by mass or more, and further preferably 80% by mass or more. It contains, particularly preferably 90% by mass or more, and most preferably 100% by mass. When the first fiber layer contains other fibers in addition to the first core-sheath type composite fiber, for example, natural fibers, regenerated fibers, and synthetic fibers can be used as the other fibers. Examples of the natural fiber include cotton, silk, wool, hemp, pulp and the like. Examples of the recycled fiber include rayon, cupra and the like. Examples of the synthetic fiber include acrylic fiber, polyester fiber, polyamide fiber, polyolefin fiber, polyurethane fiber and the like. As the other fiber, one or more kinds of fibers can be appropriately selected from the above-mentioned fibers depending on the intended use and the like.

(1st core sheath type composite fiber)
<Core component>
The core component contains 60% by mass or more of polyester resin. The core component preferably contains a polyester resin in an amount of 75% by mass or more, more preferably 85% by mass or more, and particularly preferably 90% by mass or more. The upper limit of the polyester resin contained in the core component is not particularly limited, and the core component has a structure in which all the resin components are polyester resin, that is, the core component has a structure in which all the thermoplastic resins are polyester resin. But it may be. The polyester resin contained in the core component may be one kind or two or more kinds.

The polyester resin is not particularly limited, but may have a melting point that is 50 ° C. or higher higher than the melting point of the thermoplastic resin contained in the sheath component described later, preferably 80 ° C. or higher, and 100 ° C. or higher. It is more preferable to have. When the melting point of the polyester resin is 50 ° C. or more higher than the melting point of the thermoplastic resin contained in the sheath component, not only the spinnability at the time of melt spinning is improved, but also the single fiber strength and the composite of the first composite fiber are improved. The strength of the heat-bonded non-woven fabric containing fibers becomes appropriate.

The polyester resin is not particularly limited, and either an aliphatic polyester resin or an aromatic polyester resin can be used. Examples of the polyester resin include polylactic acid (PLA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN) and the like. From the viewpoint of melting point, the polyester resin is preferably an aromatic polyester resin, more preferably at least one polyester resin selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate and polytrimethylene terephthalate, and the core. It is particularly preferable that the component contains 60% by mass or more of polyethylene terephthalate as the polyester resin. This is because polyethylene terephthalate is cheaper than polytrimethylene terephthalate and polybutylene terephthalate, and the resin itself has high rigidity and gives elasticity to the fibers, so that the resulting composite fiber is 2 Although it has a fineness of .1 dtex or less, it has an appropriate rigidity, and the card-passability of the first core-sheath type composite fiber tends to be good.

In the core component, the intrinsic viscosity of polyethylene terephthalate is preferably greater than 0.55 dL / g and less than 0.75 dL / g. When the intrinsic viscosity of polyethylene terephthalate is within the above-mentioned range, the spinnability at the time of melt spinning becomes good, the strength and rigidity of the core component are high, and the card-passability of the first core-sheath type composite fiber is good. Become. The intrinsic viscosity of polyethylene terephthalate is preferably 0.58 dL / g or more and 0.70 dL / g or less, and more preferably 0.60 dL / g or more and 0.68 dL / g or less.

In the core component, the number average molecular weight of the polyethylene terephthalate resin is not particularly limited, but is preferably 2500 or more and 6500 or less, more preferably 3000 or more and 6000 or less, and particularly preferably 3500 or more and 5500 or less. When the number average molecular weight of polyethylene terephthalate, which is the core component, satisfies the above range, the core component becomes a resin component having appropriate elasticity. Therefore, even if the first core sheath type composite fiber has a fineness of 2.1 dtex or less. Not only the card passability is improved, but also the first fiber layer and the non-woven fabric containing the first core-sheath type composite fiber tend to be excellent in tactile sensation.

In the core component, the weight average molecular weight of the polyethylene terephthalate resin is not particularly limited, but is preferably 6000 or more and 18000 or less, more preferably 8000 or more and 15000 or less, and particularly preferably 9000 or more and 14000 or less. When the weight average molecular weight of polyethylene terephthalate, which is the core component, satisfies the above range, the obtained composite fiber becomes a resin component having appropriate elasticity in the core component. The first fiber layer and the non-woven fabric containing the first core-sheath type composite fiber tend to be excellent in tactile sensation.

The core component may contain a thermoplastic resin other than the polyester resin as long as the action of the present invention is not impaired. Other thermoplastic resins are not particularly limited, and examples thereof include polyolefin resins, polyamide resins, polycarbonates, and polystyrenes.

Further, as long as the effect of the present invention is not impaired and the fiber productivity, thermal adhesiveness, and tactile sensation are not affected, various known additives can be added to the core component. Additives that can be added to the core component include known crystal nucleating agents, antistatic agents, pigments, matting agents, heat stabilizers, light stabilizers, flame retardants, antibacterial agents, lubricants, plasticizers, softeners, and antioxidants. Agents, UV absorbers, inorganic fillers and the like. Such an additive may be contained in the core component so as to occupy 10% by mass or less of the total mass of the core component.

<Sheath component>
In the first core-sheath type composite fiber, the sheath component contains 60% by mass or more of a thermoplastic resin having a melting point 50 ° C. or more lower than the melting point of the polyester resin in the core component. The thermoplastic resin having a melting point of 50 ° C. or more lower than the melting point of the polyester resin in the core component in the sheath component of the first core-sheath type composite fiber is not particularly limited, but is limited to high-density polyethylene (hereinafter, PE-HD). Alternatively, it is also described as HDPE). In the present invention, the high-density polyethylene refers to polyethylene having ^{a density of 0.94 g / cm 3 or more measured according to JIS K 7112 (1999).} Since high-density polyethylene has a higher density than other polyethylenes such as low-density polyethylene and linear low-density polyethylene, the first core-sheath composite fiber tends to have high rigidity, and the card-passability of the composite fiber, The crimping property is improved, and the obtained non-woven fabric tends to be bulky. The content of high-density polyethylene contained in the sheath component of the first core-sheath type composite fiber is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly. Preferably, in the sheath component, all the resin components except the inorganic filler described later are high-density polyethylene.

The melting point of the high-density polyethylene in the sheath component of the first core-sheath type composite fiber is not particularly limited, but in consideration of the card-passability of the composite fiber and the productivity, strength and heat resistance of the heat-bonded non-woven fabric, the temperature is 125 ° C. or higher and 140 ° C. or higher. The temperature is preferably 128 ° C or higher, and more preferably 128 ° C or higher and 138 ° C or lower. In the present invention, the melting point of high-density polyethylene is determined by measuring the melting peak temperature according to JIS K 7121 (1987).

In the first core sheath type composite fiber, the melt flow rate of the high-density polyethylene contained in the sheath component is not particularly limited, but the melt mass flow rate measured according to JIS K 7210 1 (2014) (measurement temperature 190 ° C., load). 2.16 kgf (21.18 N), hereinafter referred to as MFR190) is preferably greater than 13 g / 10 min and 45 g / 10 min or less. When the MFR190 of the high-density polyethylene is within the above range, not only the spinnability and stretchability are improved, but also the sheath component of the first core sheath type composite fiber is sufficiently rigid to pass through the card machine. The card-passability of the first core-sheath type composite fiber is improved. The MFR190 of high-density polyethylene is preferably 15 g / 10 minutes or more and 40 g / 10 minutes or less, more preferably 18 g / 10 minutes or more and 35 g / 10 minutes or less, and 18 g / 10 minutes or more and 32 g / 10 minutes or less. It is particularly preferable to have.

In the sheath component of the first core-sheath type composite fiber, the crystallite size measured for the [110] plane of the high-density polyethylene is preferably 20.0 nm or more and 50.0 nm or less, and 22.0 nm or more and 45.0 nm or less. It is more preferably 24.0 nm or more and 40.0 nm or less, and particularly preferably 24.5 nm or more and 37.5 nm or less. The crystallite size is also called the crystallite diameter and is the size of the smallest crystallite unit forming a crystal. Since the crystallite size is inversely proportional to the half-value width at the diffraction peak of the X-ray diffraction (XRD) of the object, if the crystallite size is large, that is, the crystallinity is high, the half-value width of the diffraction peak becomes small and the crystallite size becomes small. When it is small, that is, when the crystallinity is low, the half-value width of the diffraction peak becomes large.

In the sheath component of the first core-sheath type composite fiber, the crystallite size measured for the [200] plane of the high-density polyethylene is not particularly limited, but preferably, the crystallite size measured for the [200] plane is 12.0 nm or more. It is preferably 35.0 nm or less, more preferably 16.0 nm or more and 30.0 nm or less, further preferably 18.0 nm or more and 27.5 nm or less, and particularly preferably 18.5 nm or more and 25.0 nm or less. be.

The crystal face size is determined by performing wide-angle X-ray diffraction measurement on the object and measuring the half-value width with respect to the diffraction peak of the target crystal plane from the obtained 2θ-θ intensity data. It can be calculated based on the formula 1 of.

上記数式１において，
λ：入射Ｘ線波長（ｎｍ）
βe：回折ピークの半値幅（°）
βo：半値幅の補正値（°）
Ｋ：Ｓｃｈｅｒｒｅｒ定数
である。

In the above formula 1,
λ: Incident X-ray wavelength (nm)
βe: Half width of diffraction peak (°)
βo: Full width at half maximum correction value (°)
K: Scherrer constant.

In the first core-sheath type composite fiber, the heat of fusion (ΔHPE-HD) of high-density polyethylene measured by differential scanning calorimetry (DSC) is preferably 145.0 mJ / mg or more. When the heat of fusion of the high-density polyethylene contained in the sheath component is 145.0 mJ / mg or more, it can be said that the high-density polyethylene is sufficiently crystallized. The heat of fusion (ΔHPE-HD) of the high-density polyethylene is preferably 148.0 mJ / mg or more, more preferably 150.0 mJ / mg or more, and particularly preferably 152.0 mJ / mg or more. Most preferably, it is 155.0 mJ / mg or more. The upper limit of the heat of fusion (ΔHPE-HD) of the high-density polyethylene is not particularly limited, but is preferably 210.0 mJ / mg or less, more preferably 200.0 mJ / mg or less, and particularly preferably 195.0 mJ / mg or less. , 190.0 mJ / mg or less is most preferable. It is considered that both the growth and crystallization of the crystal are sufficiently advanced when the high-density polyethylene of the sheath component satisfies the above-mentioned range of crystallite size and heat of fusion, and the growth and crystallization of the crystal are promoted. , The sheath component of the first core-sheath type composite fiber becomes a highly rigid resin component. As a result, strong rigidity is imparted to the composite fiber, and even if the fineness is 2.1 dtex or less, it is considered that the composite fiber is less likely to be excessively twisted inside the card and is less likely to generate neps. In addition, by firmly fixing the crimp shape to the resin component in which the crystal growth and crystallization have sufficiently progressed, the crimp shape is less likely to collapse and the card passability is further improved. Conceivable.

In the first core sheath type composite fiber, the heat of fusion (ΔHPE-HD) of the high-density polyethylene contained in the sheath component is measured by the following procedure.
First, the core-sheath ratio (volume ratio) of the composite fiber for determining the heat of fusion of high-density polyethylene is determined from the density and addition amount of the thermoplastic resin and the inorganic filler constituting each of the core component and the sheath component. The volume ratio) is converted into the core-sheath ratio (mass ratio), and the ratio of high-density polyethylene to the composite fiber (mass ratio of high-density polyethylene) is obtained from the ratio of the inorganic filler contained in the sheath component. Next, the differential scanning calorimetry is performed on the composite fiber as a sample based on the transition temperature measurement method of JIS K 7121 (1987) plastic. By differential scanning calorimetry, the endothermic peak has a melting peak temperature in the temperature range of 125 ° C to 140 ° C (the endothermic heat associated with melting is observed from about 120 ° C, and the melting peak temperature is reached from 125 ° C to 140 ° C, resulting in melting. The endothermic process that accompanies it ends at about 150 ° C.) is observed. From the heat of fusion (ΔH) measured between about 120 ° C. and about 150 ° C., the heat of fusion (ΔH _PE-HD ) of the high-density polyethylene contained in the composite fiber is calculated by the following formula 2.

In the first core-sheath type composite fiber, the sheath component may contain, in addition to the high-density polyethylene, a resin other than the above-mentioned high-density polyethylene as long as the action of the present invention is not impaired. The other resin is not particularly limited, and examples thereof include polyolefin resins other than high-density polyethylene, polyester resins, polyamide resins, polycarbonates, polystyrenes, and the like.

In the first core sheath type composite fiber, the sheath component may contain various known additives, if necessary. Examples of the additive that can be added to the sheath component include known crystal nucleating agents, antistatic agents, pigments, matting agents, heat stabilizers, light stabilizers, and antifusion agents (metal soaps such as talc and calcium stearate). ), Flame retardants, antibacterial agents, lubricants, plasticizers, fabric softeners, antioxidants, UV absorbers, inorganic fillers and the like. Such an additive may be contained in the sheath component so as to occupy 10% by mass or less of the total mass of the sheath component.

The first core-sheath type composite fiber preferably contains 0.5% by mass or more and 10% by mass or less of an inorganic filler with respect to 100% by mass of the composite fiber, and more preferably 0.8% by mass or more and 8% by mass or less. It is more preferably 1.0% by mass or more and 6% by mass or less, particularly preferably 1.2% by mass or more and 5% by mass or less, and most preferably 1.3% by mass or more and 3.5% by mass or less. .. By containing the inorganic filler in the above range, the first core-sheath type composite fiber has a high whiteness, that is, a whiteness, in the appearance of the non-woven fabric for absorbent articles. In addition, since the fineness of the first core-sheath type composite fiber is 2.1 dtex or less, not only the surface of the first fiber layer containing the first core-sheath type composite fiber easily reflects visible light diffusely, but also If the non-woven fabric has the same texture, the number of fibers constituting the non-woven fabric increases, so that the whiteness of the non-woven fabric for absorbent articles tends to be further increased. Due to the high whiteness of the non-woven fabric for absorbent articles, when the absorbent articles absorb excrement such as menstrual blood and urine, the menstrual blood, urine, etc. absorbed by the absorber located under the surface sheet The color of excrement becomes difficult to see from the surface, so-called concealment becomes high. Since the first core-sheath type composite fiber contains an inorganic filler, it exhibits excellent concealment properties, and by containing the inorganic filler, the first core-sheath type composite fiber itself and the non-woven fabric for absorbent articles containing the tactile sensation. Also tends to be soft. The inorganic filler may be contained in either one of the sheath component and the core component constituting the first core-sheath type composite fiber, or may be contained in both. From the viewpoint of hiding the non-woven fabric for absorbent articles, it is preferable that at least the core component of the first core-sheath type composite fiber contains an inorganic filler. When the content of the inorganic filler with respect to 100% by mass of the first core-sheath type composite fiber exceeds 4% by mass or 5% by mass, if the inorganic filler is contained in only one of the sheath component and the core component, it is inorganic. Since the spinnability of the resin component containing the filler is extremely lowered, it is preferable to include the inorganic filler in both the sheath component and the core component.

From the viewpoint of further enhancing the hiding property, the inorganic filler is preferably an inorganic powder having a high degree of whiteness. Specifically, white inorganic powders such as titanium dioxide (TiO ₂ , hereinafter simply referred to as titanium oxide), zinc oxide, barium sulfate, calcium carbonate, magnesium oxide, silica (silicon dioxide), mica, zeolite, and talc. Can be mentioned. The inorganic filler is preferably at least one selected from the group consisting of titanium dioxide, zinc oxide, calcium carbonate, barium sulfate, silica and talc, and more preferably titanium oxide. The above-mentioned inorganic filler may be used alone or in combination of two or more.

The first core-sheath type composite fiber is preferably a core-sheath type composite fiber having a concentric structure in which the core component and the sheath component are arranged substantially concentrically. FIG. 2 is a schematic cross-sectional view showing a fiber cross section of a core-sheath type composite fiber having a concentric circular structure. As shown in FIG. 2, in the core-sheath type composite fiber 2 having a concentric structure, the sheath component 21 and the core component 22 are arranged substantially concentrically. That is, in the fiber cross section, the center of gravity position 23 of the core component 22 is not substantially deviated from the center of gravity position 24 of the core-sheath type composite fiber 2. When the first core-sheath type composite fiber is a core-sheath type composite fiber having a concentric structure, the sheath component 21 is arranged around the core component 22 in this way, and the sheath component 21 surrounds the core component 22. In the core-sheath type composite fiber 2 having a concentric structure, the fiber surface other than the cut surface is covered with the sheath component 21. As a result, when the fiber web composed of the first core-sheath type composite fiber having a concentric structure is heat-bonded, the sheath components constituting the surface of the first core-sheath type composite fiber are melted and the fibers are heat-bonded to each other. When the first core-sheath type composite fiber has a concentric structure, the thickness of the sheath component in the fiber cross section is substantially constant at any part of the fiber cross section. As a result, when the fiber web composed of the first core-sheath type composite fiber is heat-treated, the sheath component on the fiber surface is softened and melted. Since thermal adhesion points having uniform strength are formed even when the fibers come into contact with each other, the first fiber layer using the first core-sheath type composite fiber has high adhesive strength, is resistant to friction, and is less likely to fluff. The fact that the position of the center of gravity of the core component does not substantially deviate from the position of the center of gravity of the composite fiber means that the rate of deviation (hereinafter, also referred to as eccentricity) obtained by the following method is 10% or less, preferably 7% or less. It means that it is particularly preferably 5% or less, and most preferably 3% or less.

For the eccentricity of the core-sheath type composite fiber, the fiber cross section of the core-sheath type composite fiber is magnified and photographed with a scanning electron microscope or the like, the center of gravity position 23 of the core component 22 is set to C1, and the center of gravity position 24 of the core-sheath type composite fiber 2 is set. Is Cf, and the radius 25 of the core-sheath type composite fiber is rf.

In the first core-sheath type composite fiber, the composite ratio of the core component and the sheath component is preferably 30/70 to 60/40 in terms of the volume ratio of the core component / sheath component, and is 33/67 to 55/45. Is more preferable, 35/65 to 50/50 is particularly preferable, and 35/65 to 48/52 is most preferable. When the composite ratio of the core component and the sheath component in the first core-sheath type composite fiber is within the above-mentioned range, the card-passability of the first core-sheath type composite fiber and the heat-bonded non-woven fabric containing the first core-sheath type composite fiber Both adhesive strength and tactile sensation can be achieved.

In the first core-sheath type composite fiber, the shape of the core component in the fiber cross section may be an elliptical shape, a Y shape, an X shape, a well shape, a polygonal shape, a star shape, or the like, in addition to the circular shape. The shape of the sheath-shaped composite fiber in the fiber cross section may be an elliptical shape, a Y-shaped, an X-shaped, a well-shaped, a polygonal shape, a star-shaped or other irregular shape, or a hollow shape, in addition to the circular shape.

The first core-sheath type composite fiber has a single fiber fineness of 0.5 dtex or more and 2.1 dtex or less. When the fineness of the first core-sheath type composite fiber is 2.1 dtex or less, the non-woven fabric for absorbent articles tends to have a soft and smooth feel and a high hiding property. The fineness of the first core-sheath type composite fiber is preferably 1.8 dtex or less, and more preferably 1.7 dtex or less. When the fineness is 0.5 dtex or more, the card-passability of the first core-sheath type composite fiber is improved, and the productivity is also improved. The fineness of the first core-sheath type composite fiber is preferably 0.8 dtex or more, more preferably 1.0 dtex or more, and particularly preferably 1.1 dtex or more.

The single fiber strength of the first core-sheath type composite fiber is not particularly limited, but is preferably 1.5 cN / dtex or more and 5.0 cN / dtex or less. When the single fiber strength satisfies the above range, the first core-sheath type composite fiber has an appropriate strength and an appropriate rigidity, and the card passability and the handleability of the fiber web during the production of the non-woven fabric are good. Become. The single fiber strength of the composite fiber is more preferably 1.6 cN / dtex or more and 4.0 cN / dtex or less, further preferably 1.8 cN / dtex or more and 3.8 cN / dtex or less, and 2.0 cN / dtex or less. It is particularly preferable that the content is 3.5 cN / dtex or less.

The elongation at break of the first core-sheath type composite fiber is not particularly limited, but is preferably 20% or more and 150% or less. When the elongation at break satisfies the above range, the first core-sheath type composite fiber has an appropriate strength and an appropriate rigidity, and the card passability of the first core-sheath type composite fiber and the fiber web at the time of producing a non-woven fabric The handleability is good. The breaking elongation of the composite fiber is more preferably 25% or more and 120% or less, further preferably 25% or more and 100% or less, further preferably 30% or more and 80% or less, and 30%. It is particularly preferable that it is 60% or more and 60% or less. In the present invention, the single fiber strength and the elongation at break of the first core-sheath type composite fiber are measured according to JIS L 1015 (2010).

The first core-sheath type composite fiber has at least one type of crimp selected from the group consisting of serrated crimps (also referred to as mechanical crimps) shown in FIG. 3A and wavy crimps shown in FIG. 3B. The number of crimps is preferably 5 pieces / 25 mm or more and 25 pieces / 25 mm or less. It is possible to obtain a non-woven fabric for an absorbent article that is flexible and has a smooth texture without deteriorating the card passability. A more preferable number of crimps is 8 pieces / 25 mm or more and 20 pieces / 25 mm or less, and a more preferable number of crimps is 10 pieces / 25 mm or more and 20 pieces / 25 mm or less. Further, the first core-sheath type composite fiber has a crimp ratio of 5% or more and 20% or less from the viewpoint of the card-passability of the composite fiber and the tactile sensation and bulk recovery of the non-woven fabric containing the first core-sheath type composite fiber. It is preferably 6% or more and 18% or less, and more preferably 6.5% or more and 16% or less.

The fiber length of the first core-sheath type composite fiber is not particularly limited, but is preferably 25 mm or more and less than 65 mm in consideration of card passability. When the fiber length satisfies this range, even if the first core-sheath type composite fiber has a fineness, it is possible to produce a card web having excellent card passability and a good texture. In the case of fine fibers, if the fiber length is less than 25 mm, the fiber length is too short to be caught in the card, that is, a so-called fly state is likely to occur, and the card web may not be manufactured. In the case of fine fibers, if the fiber length is 65 mm or more, the composite fibers are often caught in the wire of the card machine, or the composite fibers are easily entangled with each other, so that the fibers are gathered in a fluffy shape, so-called NEP. , There is a risk that the card web cannot be manufactured. The fiber length of the first core-sheath type composite fiber is more preferably 28 mm or more and 55 mm or less, further preferably 30 mm or more and 48 mm or less, and particularly preferably 34 mm or more and 45 mm or less.

<First fiber treatment agent>
The first fiber treatment agent contains a component A composed of a linear alkyl phosphate ester salt having 6 or more and 22 or less carbon atoms in the alkyl chain, and the component A is a component having 16 carbon atoms in at least one alkyl group. It contains a1, a component a2 having at least one alkyl group having 18 carbon atoms, and a component a3 having at least one alkyl group having 10 or less carbon atoms, and the mass ratio a1 / a2 of the component a1 and the component a2 is 1.0 or more. It is 3.4 or less, the mass ratio a3 / (a1 + a2) of the component a3 to the total mass of the component a1 and the component a2 is 3.0 or less, and the total content of the component a1 and the component a2 in the first fiber treatment agent. Is 7% by mass or more and 12% by mass or less. When such a first fiber treatment agent adheres to the surface of the first core-sheath type composite fiber, the tactile sensation, liquid absorption property, and liquid return property are enhanced.

The component A is preferably composed mainly of a phosphoric acid monoester salt and a phosphoric acid diester salt represented by the following general formula (I) and containing the largest amount of phosphoric acid monoester salt. In addition to these, the component A may contain a polyphosphate or the like. Component A is typically a mixture of these.

In the above general formula (I), Ra represents ^a linear alkyl group, M represents a cation, and n represents an integer of 1 or 2. When ^{there are a plurality of Ra} and M, each of them may be the same or different from each other.

The cation M in the component A is not particularly limited, and examples thereof include hydrogen, alkali metals, alkaline earth metals, magnesium, and organic ammonium. Examples of the alkali metal include lithium, sodium, potassium and the like. Examples of the alkaline earth metal include calcium and the like. Examples of the organic ammonium include those represented by ^{NR 1} R ² R ³ R ^4. Here, R ^{1 to} R ⁴ independently represent a hydrogen atom, an alkyl group, a hydroxyalkyl group, and a polyalkylene glycol group, respectively. Among these, any alkali metal selected from sodium and potassium, ammonium, and organic ammonium having an alkyl group or hydroxyalkyl group having 20 or less carbon atoms, preferably 10 or less, and more preferably 5 or less carbon atoms are preferable.

Examples of the linear alkyl phosphate ester salt of component A include hexyl phosphate ester salt, octyl phosphate ester salt, decyl phosphate ester salt, dodecyl phosphate ester salt (lauryl phosphate ester salt), tridecyl phosphate ester salt, and tetra. Examples thereof include decyl phosphate ester salt (myristyl phosphate ester salt), hexadecyl phosphate ester salt (cetyl phosphate ester salt), octadecyl phosphate ester salt (stearyl phosphate ester salt) and the like.

The method for producing component A in the first fiber treatment agent is not particularly limited, but a method of neutralizing with an alkaline substance after a solvent-free reaction of a linear alkyl alcohol having a corresponding alkyl group and diphosphorus pentoxide is used. The desired compound can be easily obtained. When this method is used, the reaction molar ratio of the linear alkyl alcohol having the corresponding alkyl group to diphosphorus pentoxide [(phosphorylation degree) = the number of moles of the linear alkyl alcohol having the corresponding alkyl group / dipentoxide The amount of phosphoric acid monoester produced varies depending on the number of moles of phosphorus], but the degree of phosphorylation is 2.0 or more 3 from the viewpoint of card-passability, hydrophilicity, and antistatic property of the first core-sheath type composite fiber. It is preferably 0.0 or less, and more preferably 2.2 or more and 2.8 or less.

The first fiber treatment agent contains, as the component A, a component a1 composed of a linear alkyl phosphate ester salt and having an alkyl group having 16 carbon atoms and a component a2 having an alkyl group having 18 carbon atoms. By including the component a1 and the component a2, the durability hydrophilicity of the first core-sheath type composite fiber becomes better.

In the first fiber treatment agent, the mass ratio a1 / a2 of the component a1 and the component a2 is 1.0 or more and 3.4 or less, preferably 3.0 or less. As a result, the handleability of the first fiber treatment agent is improved, and the durability hydrophilicity of the first core-sheath type composite fiber is also improved.

Examples of the alkyl group of the component a1 and the component a2 include a hexadecyl group (cetyl group) and an octadecyl group (stearyl group) in the case of a phosphoric acid monoester salt. In the case of a phosphoric acid diester salt, in addition to a hexadecyl group (cetyl group) and an octadecyl group (stearyl group), for example, a butyl group, a hexyl group, an octyl group, a nonyl group, a decyl group, an undecyl group and a dodecyl group ( Lauryl group), tridecyl group, tetradecyl group, pentadecyl group, hebutadecyl group, nonadecil group, icosyl group, henicosyl group, docosyl group and the like may be included. The component a1 and the component a2 may be a mixture of compounds having different alkyl groups. In this case, the component a1 has an alkyl group having 16 carbon atoms, and the component a2 has an alkyl group having 18 carbon atoms. It is essential to include at least one in it.

The first fiber treatment agent further contains, as the component A, a component a3 having at least one alkyl group having 10 or less carbon atoms, in addition to the component a1 and the component a2. The mass ratio a3 / (a1 + a2) of the component a3 to the total mass (a1 + a2) of the component a1 and the component a2 is 3.0 or less. As a result, the permeability of the first fiber treatment agent, the durability hydrophilicity of the first core-sheath type composite fiber, and the card passability are improved. The mass ratio a3 / (a1 + a2) of the component a3 to the total mass (a1 + a2) of the component a1 and the component a2 is preferably 3.0 or less, more preferably 2.5 or less, and 2.0 or less. It is particularly preferable to have.

In the first fiber treatment agent, the total content of the component a1 and the component a2 is 7% by mass or more and 12% by mass or less. This makes it easier to impart durable hydrophilicity to the first core-sheath type composite fiber.

The first fiber treatment agent may contain, as the component A, a linear alkyl phosphate ester salt having at least one alkyl having 11 or more and 15 or less carbon atoms.

In addition to the component A, the first fiber treatment agent may contain other components as long as the effects of the present invention are not impaired. Other ingredients include, for example, surfactants, hydrophilic silicone resins, penetrants, smoothing agents, antibacterial agents, antioxidants, preservatives, matting agents, pigments, antiseptic agents, fragrances, defoaming agents, etc. Examples include fragrances, pH adjusters, viscosity adjusters and the like.

Examples of the surfactant include nonionic surfactants such as polyoxyalkylene alkyl ether, polyoxyalkylene alkenyl ether, polyoxyalkylene fatty acid ester, and fatty acid alkanolamide, alpha olephine sulfonate, alkylbenzene sulfonate, and alkyl. Anionic surfactants such as sulfates, polyoxyalkylene alkyl ether sulfates, and sulfosuccinic acid ester salts, amphoteric surfactants such as alkylbetaine and alkylsulfobetaine, and alkylamino fatty acid salts, alkyl quaternary ammonium salts, etc. Cationic surfactants and the like can be mentioned.

The first fiber treatment agent contains water or a solvent for dissolving the component A, and preferably contains water. The water may be pure water, distilled water, purified water, soft water, ion-exchanged water, tap water, or the like. The ratio of the solid content (active ingredient) in the first fiber treatment agent is not particularly limited, but is preferably 5% by mass or more and 90% by mass or less, and more preferably 10% by mass or more and 80% by mass or less. In the present invention, the "solid content of the fiber treatment agent" is a ratio excluding volatile components such as water and a solvent.

<Manufacturing method of first core-sheath type composite fiber>
First, in the fiber cross section, a composite nozzle arranged so that the surface of the composite fiber is covered with a sheath component and the position of the center of gravity of the core component coincides with the position of the center of gravity of the composite fiber is a concentric structure, for example, a concentric core-sheath composite. The sheath component and the core component are supplied to the nozzle to perform melt spinning. At this time, for example, the temperature at which the core component is melted and extruded (spinning temperature) is 280 ° C. or higher and 380 ° C. or lower, and the temperature at which the sheath component is melted and extruded (spinning temperature) is 250 ° C. or higher and 350 ° C. or lower. Melt spinning is performed at a temperature of 250 ° C. or higher and 350 ° C. or lower.

The number of holes in the concentric sheath-type composite nozzle is preferably, for example, 300 or more and 5000 or less, and preferably 450 or more and 3500 or less. When the number of holes satisfies the above range, melt spinning can be performed under the condition that the draft ratio is high in a stable state.

In the nozzle, for example, the hole diameter is preferably 0.2 mm or more and 0.8 mm or less, and more preferably 0.25 mm or more and 0.75 mm or less. When the hole diameter satisfies the above range, melt spinning can be performed under the condition that the draft ratio is high in a stable state.

The molten core component and sheath component are extruded from the holes provided in the nozzle to perform melt spinning. At this time, the value obtained by dividing the total amount of resin extruded from the nozzle in 1 minute by the number of holes, that is, the amount of the melted core component and sheath component extruded in 1 minute per hole (hereinafter, resin discharge per single hole). The amount is not particularly limited, but is preferably 0.2 g / min or more and 1 g / min or less, and more preferably 0.25 g / min or more and 0.8 g / min or less. When the resin discharge amount per single hole satisfies the above range, melt spinning can be performed under the condition that the draft ratio is high in a stable state.

The melted core component and sheath component extruded from the holes provided in the nozzle are cooled while being taken up at high speed to obtain an undrawn fiber tow. At this time, the speed at which the molten core component and sheath component are picked up (hereinafter referred to as the pick-up speed) is not particularly limited, but is preferably 500 m / min or more and 2500 m / min or less, and 600 m / min or more and 2300 m / min or more. It is more preferably less than a minute, and particularly preferably 650 m / min or more and 2000 m / min or less. When the take-up speed satisfies the above range, melt spinning can be performed at a high draft ratio in a stable state.

In melt spinning, the draft ratio is preferably 350 or more and 1500 or less. When the draft ratio satisfies the above range, a strong tension is applied to the core component and the sheath component in the molten state along the length direction of the fiber during melt spinning. In particular, when a strong tension is applied to the sheath component (high-density polyethylene) constituting the outer side of the undrawn fiber tow, the crystallization of the high-density polyethylene is promoted, the melt spinning is completed, and the undrawn fiber taken over. In the tow, high-density polyethylene tends to be in a state where the crystallite size is increased due to the progress of crystallization and its growth. The draft ratio is preferably 400 or more and 1400 or less, more preferably 500 or more and 1300 or less, and particularly preferably 600 or more and 1250 or less.

The draft ratio in melt spinning is calculated by the following mathematical formula 4.

上記数式４において
Ｖ_s：引き取り速度（ｃｍ／分）
ｄ：ホール径（ｃｍ）
Ｗ_h：単孔あたりの樹脂吐出量（ｇ／分）
なお、溶融比重は芯成分及び鞘成分の溶融時の比重であり、溶融紡糸時と同じ温度に設定された押出機から一定体積の溶融樹脂を押し出し、押し出された樹脂の質量を測定し、押し出された樹脂の質量を上記一定体積で除することで測定できる。

In the above formula 4, V _s : Pick-up speed (cm / min)
d: Hole diameter (cm)
W _h : Resin discharge amount per single hole (g / min)
The melt specific gravity is the specific gravity when the core component and the sheath component are melted, and a certain volume of molten resin is extruded from an extruder set to the same temperature as during melt spinning, and the mass of the extruded resin is measured and extruded. It can be measured by dividing the mass of the resin obtained by the above constant volume.

The undrawn fiber tow has a single fiber fineness of 1.8 dtex or more and 4.5 dtex or less, more preferably 2.0 dtex or more and 4.2 dtex or less, and 2.2 dtex or more and 4.0 dtex or less. Is more preferable, and it is particularly preferable that the amount is 2.2 dtex or more and 3.8 dtex or less.

The undrawn fiber tow preferably has an elongation of 100% or more and 400% or less, more preferably 120% or more and 300% or less, and particularly preferably 140% or more and 250% or less.

Next, it is preferable to stretch the undrawn fiber tow at a temperature of 70 ° C. or higher and 120 ° C. or lower at a draw ratio of 1.6 times or more and 3.6 times or less. As a result, a first core-sheath type composite fiber having sufficient rigidity and elasticity and having a fine fineness that allows good card passage can be obtained. The lower limit of the more preferable stretching temperature is 75 ° C. or higher, and the lower limit of the particularly preferable stretching temperature is 80 ° C. or higher. The lower limit of the more preferable draw ratio is 1.8 times or more, and the lower limit of the particularly preferable draw ratio is 2.0 times or more. The upper limit of the more preferable draw ratio is 3.4 times or less, and the upper limit of the particularly preferable draw ratio is 3.2 times or less.

The stretching method is not particularly limited, and wet stretching is performed while heating the unstretched fiber tow using a high-temperature liquid such as hot water as a medium, and stretching is performed while heating in a high-temperature gas or a high-temperature metal roll. Known stretching treatments such as dry stretching and steam stretching in which the fibers are heated while the fibers are heated under normal pressure or pressure at 100 ° C. or higher can be performed. Of these, wet stretching using warm water or dry stretching using a high-temperature gas or a high-temperature metal roll is preferable, and the tension during stretching and the heat during stretching are applied to the single fibers constituting the undrawn fiber tow. Wet stretching is more preferable because it is easy and evenly applied. The stretching may be a so-called one-step stretching in which the stretching step is only one step, a two-step stretching in which the stretching step is two steps, or a multi-step stretching in which the stretching step exceeds two steps. Further, before and after the stretching treatment, an annealing treatment may be performed, if necessary.

Next, the first fiber treatment agent is applied to the drawn fiber tow. The first fiber treatment agent can be used as an aqueous solution or an emulsion dispersion diluted with water, if necessary. For example, a treatment tank filled with an aqueous solution of the first fiber treatment agent is impregnated with the drawn fiber tow, and an excess aqueous solution of the first fiber treatment agent is squeezed out with a nip roll or the like to apply the first fiber treatment agent to the drawn fiber tow. Can be granted. The first fiber treatment agent may be applied after the crimping is applied. Further, the first fiber treatment agent may be applied by means such as spraying in addition to the dipping method.

The first fiber treatment agent is not particularly limited, but from the viewpoint of liquid absorption and liquid return, the component A (active component) is 0.30 mass by mass with respect to the mass of the drawn fiber tow (first core sheath type composite fiber). It is preferably added so as to be% or more and 0.60% by mass or less, more preferably 0.33% by mass or more and 0.55% by mass or less, and further preferably 0.35% by mass or more and 0.50% by mass or less. It is as follows.

なお、吸収性物品用不織布の第１繊維層から第１芯鞘型複合繊維４ｇを採集し、上述したとおりに、第１芯鞘型複合繊維の繊維処理剤の付着量を測定してもよい。 In the present invention, the amount of the fiber treatment agent attached to the first core-sheath type composite fiber can be measured by a rapid extraction method using an R-II type rapid residual fat extractor manufactured by Tokai Keiki Co., Ltd.
(1) 4 g of fibers cut to a predetermined length are applied to a card machine to form a fiber web, and the mass (W _f ) of the obtained fiber web is measured.
(2) After filling the mass-measured fiber web into a metal cylinder (inner diameter 16 mm, length 130 mm, mortar-shaped bottom with 1 mm hole at the bottom), 10 mL of methanol is added from the top. ..
(3) Methanol in which the fiber treatment agent adhering to the fiber sample is dissolved, which is dropped from the hole at the bottom, is _{received while heating an aluminum dish (mass: W 1} ) to evaporate the methanol. The mass of the aluminum dish (W ₁ ) is measured after the aluminum dish has been sufficiently dried in a dryer and before receiving methanol. After the methanol has completely evaporated, the mass (W ₂ ) of the aluminum dish on which the fiber treatment agent remains is measured.
(4) The amount of the fiber treatment agent attached to the mass of the fiber is calculated from the following formula.

In addition, 4 g of the first core-sheath type composite fiber may be collected from the first fiber layer of the non-woven fabric for absorbent articles, and the amount of the fiber treatment agent attached to the first core-sheath type composite fiber may be measured as described above. ..

Next, crimping is applied to the drawn fiber toe using a known crimping machine such as a stuffing box type crimper, but the shape of the crimped fiber toe is not easily lost, in other words, the shape is easily maintained. In order to impart crimp, it is preferable to impart crimp while the drawn fiber tow is sufficiently heated.

The heating of the drawn fiber tow is preferably performed in a state where the drawn fiber tow is given an appropriate tension. Specifically, in the toe heating step, it is preferable to perform toe heating under a tension state in which the magnification is 0.95 times or more and 1.3 times or less. The heating temperature is preferably 80 ° C. or higher and 120 ° C. or lower, more preferably 90 ° C. or higher and 110 ° C. or lower. The heating time is not particularly limited, but is preferably 0.5 seconds or more and 10 seconds or less, more preferably 1 second or more and 5 seconds or less, and further preferably 1 second or more and 3 seconds or less.

The number of crimps is not particularly limited, but is preferably 5 pieces / 25 mm or more and 28 pieces / 25 mm or less, more preferably 8 pieces / 25 mm or more and 25 pieces / 25 mm or less, and 10 pieces / 25 mm or more and 20 pieces / It is particularly preferably 25 mm or less. The crimp shape after passing through the crimping machine is not particularly limited, but it is preferable that at least one crimp shape selected from serrated crimp and wavy crimp is expressed.

Further, it is preferable to perform an annealing treatment after applying crimping with the crimping machine. The annealing treatment is preferably performed in a temperature range of 80 ° C. or higher and 120 ° C. or lower in an atmosphere such as dry heat, moist heat, or steam heat, and more preferably in a temperature range of 90 ° C. or higher and 120 ° C. or lower. Specifically, it is preferable that the drawn fiber tow that has been crimped by a crimping machine is dried at the same time as the annealing treatment in a dry heat atmosphere of 90 ° C. or higher and 120 ° C. or lower because the process can be simplified.

The single fiber fineness of the first core-sheath type composite fiber can be adjusted as desired by adjusting the single fiber fineness and the draw ratio of the undrawn fiber tow. After the annealing treatment described above, the drawn fiber toe is cut to obtain a first core-sheath type composite fiber having a predetermined length.

(Second fiber layer)
The second fiber layer contains 60% by mass or more of a polyester resin as a core component, 60% by mass or more of a thermoplastic resin having a sheath component having a melting point of 50 ° C. or more lower than the melting point of the polyester resin, and has a single fiber fineness of 2. It is a fiber layer containing .2 dtex or more and 7.0 dtex or less, and 50% by mass or more of the second core-sheath type composite fiber in which the second fiber treatment agent is attached to the fiber surface. From the viewpoint of excellent liquid absorption characteristics, the second fiber layer preferably contains the second core-sheath type composite fiber in an amount of 60% by mass or more, more preferably 70% by mass or more, and further preferably 80% by mass or more. It is particularly preferably contained in an amount of 90% by mass or more, and most preferably composed of 100% by mass. When the second fiber layer contains other fibers in addition to the second core-sheath type composite fiber, for example, natural fibers, regenerated fibers, and synthetic fibers can be used as the other fibers. Examples of the natural fiber include cotton, silk, wool, hemp, pulp and the like. Examples of the recycled fiber include rayon and cupra. Examples of the synthetic fiber include acrylic fiber, polyester fiber, polyamide fiber, polyolefin fiber, polyurethane fiber and the like. As the other fiber, one or more kinds of fibers can be appropriately selected from the above-mentioned fibers depending on the intended use and the like.

<Second core sheath type composite fiber>
The second core-sheath type composite fiber has a fineness of 2.2 dtex or more and 7.0 dtex or less. By making the fineness of the second core-sheath type composite fiber constituting the second fiber layer larger than the fineness of the first core-sheath type composite fiber constituting the first fiber layer, the non-woven fabric for absorbent articles has an appropriate cushioning property. The tactile sensation is smooth and the liquid absorption characteristics are also good. When the fineness of the second core-sheath type composite fiber is less than 2.2 dtex, even if the second core-sheath type composite fiber is an eccentric core-sheath type composite fiber, the fineness is small and the constituent fibers of the second fiber layer are formed. As a result, the second fiber layer has a dense structure, and it becomes difficult to absorb excrement such as menstrual blood and urine. Further, when the fineness of the second core-sheath type composite fiber exceeds 7.0 dtex, the number of constituents of the second fiber layer is relatively small due to the large fineness of the second core-sheath type composite fiber, and as a result, the second core-sheath type composite fiber is composed. 2 The fiber layer becomes too sparse, the capillary phenomenon is less likely to occur, and excrement such as menstrual blood and urine is less likely to be absorbed. The fineness of the second core-sheath type composite fiber is more preferably 2.6 dtex or more and 6.5 dtex or less, and further preferably 3.0 dtex or more and 5.6 dtex or less.

<Core component>
In the second core-sheath type composite fiber, the core component contains 60% by mass or more of polyester resin, preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably. It consists of 100% by mass. When the core component contains 60% by mass or more of the polyester resin, the card passability of the second core-sheath type composite fiber is improved.

The polyester resin is not particularly limited, and either an aliphatic polyester resin or an aromatic polyester resin can be used. Examples of the polyester resin include polylactic acid (PLA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN) and the like. From the viewpoint of melting point, the polyester resin is preferably an aromatic polyester resin, and more preferably at least one polyester resin selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polytrimethylene terephthalate. It is particularly preferable that the component contains 60% by mass or more of polyethylene terephthalate as the polyester resin.

The intrinsic viscosity of the polyethylene terephthalate is preferably greater than 0.55 dL / g and less than 0.75 dL / g. When the intrinsic viscosity of polyethylene terephthalate is within the above-mentioned range, the spinnability at the time of melt spinning becomes good, the strength and rigidity of the core component are high, and the card-passability of the first core-sheath type composite fiber is good. Become. The intrinsic viscosity of polyethylene terephthalate is preferably 0.58 dL / g or more and 0.70 dL / g or less, and more preferably 0.60 dL / g or more and 0.68 dL / g or less.

The core component may contain a thermoplastic resin other than the polyester resin as long as the action of the present invention is not impaired. Other thermoplastic resins are not particularly limited, and examples thereof include polyolefin resins, polyamide resins, polycarbonates, and polystyrenes.

Further, as long as the effect of the present invention is not impaired and the fiber productivity, thermal adhesiveness, and tactile sensation are not affected, various known additives can be added to the core component. Additives that can be added to the core component include known crystal nucleating agents, antistatic agents, pigments, matting agents, heat stabilizers, light stabilizers, flame retardants, antibacterial agents, lubricants, plasticizers, softeners, and antioxidants. Agents, UV absorbers, inorganic fillers and the like. Such an additive may be contained in the core component so as to occupy 10% by mass or less of the total mass of the core component.

<Sheath component>
In the second core-sheath type composite fiber, the thermoplastic resin having a melting point lower than that of the polyester resin contained in the core component by 50 ° C. or more is not particularly limited, but it is preferable to use high-density polyethylene. Since the sheath component of the second core-sheath type composite fiber contains high-density polyethylene, the second core-sheath type composite fiber tends to have high rigidity, and the second core-sheath type composite fiber has card-passability and crimping property. Tends to be good. The content of high-density polyethylene contained in the sheath component of the second core-sheath type composite fiber is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly. It is preferably 100% by mass. As the high-density polyethylene, high-density polyethylene that can be used as a sheath component of the first core-sheath type composite fiber described above can be used. It is preferable that the high-density polyethylene contained in the sheath component of the first core-sheath type composite fiber and the high-density polyethylene contained in the sheath component of the second core-sheath type composite fiber have substantially the same melting point. The first core-sheath type composite fiber and the second core-sheath type composite fiber are easily heat-bonded by the sheath component of the first core-sheath type composite fiber and the second core-sheath type composite fiber. In the sheath component of the second core sheath type composite fiber, the high-density polyethylene preferably has an MFR190 of 6 g / 10 minutes or more and 30 g / 10 minutes or less, more preferably 7 g / 10 minutes or more, from the viewpoint of fiber rigidity. It is 24 g / 10 minutes or less, more preferably 8 g / 10 minutes or more and 22 g / 10 minutes or less.

In the second core sheath type composite fiber, the sheath component may contain a resin other than the high density polyethylene as long as the action of the present invention is not impaired, in addition to the high density polyethylene. The resin other than the high-density polyethylene is not particularly limited, and examples thereof include a polyolefin resin other than the high-density polyethylene, a polyester resin, a polyamide resin, a polycarbonate, and polystyrene.

In the second core sheath type composite fiber, the sheath component may contain various known additives, if necessary. Examples of the additive that can be added to the sheath component include known crystal nucleating agents, antistatic agents, pigments, matting agents, heat stabilizers, light stabilizers, and antifusion agents (metal soaps such as talc and calcium stearate). ), Flame retardants, antibacterial agents, lubricants, plasticizers, fabric softeners, antioxidants, UV absorbers, inorganic fillers and the like. Such an additive is preferably contained in the sheath component so as to occupy 10% by mass or less of the total mass of the sheath component.

Like the first core-sheath type composite fiber, the second core-sheath type composite fiber is preferably a core-sheath type composite fiber having a concentric circle structure in which the core component and the sheath component are arranged substantially concentrically.

In the second core-sheath type composite fiber, the composite ratio of the core component and the sheath component is the volume ratio of the core component / sheath component, and the composite ratio of the core component and the sheath component is 30/70 to 60 in the volume ratio of the core component / sheath component. It is preferably / 40, more preferably 33/67 to 55/45, particularly preferably 35/65 to 50/50, and most preferably 35/65 to 48/52. When the composite ratio of the core component to the sheath component in the second core-sheath type composite fiber is within the above-mentioned range, the card-passability of the second core-sheath type composite fiber and the heat-bonded non-woven fabric containing the second core-sheath type composite fiber Both adhesive strength can be achieved.

In the second core-sheath type composite fiber, the shape of the core component in the fiber cross section may be an elliptical shape, a Y shape, an X shape, a well shape, a polygonal shape, a star shape, or the like, in addition to the circular shape. The shape of the sheath-shaped composite fiber in the fiber cross section may be an elliptical shape, a Y-shaped, an X-shaped, a well-shaped, a polygonal shape, a star-shaped or other irregular shape, or a hollow shape, in addition to the circular shape.

The second core-sheath composite fiber has at least one type of crimp selected from the group consisting of serrated crimps (also referred to as mechanical crimps) shown in FIG. 3A and wavy crimps shown in FIG. 3B. The number of crimps is preferably 5 pieces / 25 mm or more and 25 pieces / 25 mm or less. It is possible to obtain a non-woven fabric for an absorbent article that is flexible and has a smooth texture without deteriorating the card passability. A more preferable number of crimps is 8 pieces / 25 mm or more and 20 pieces / 25 mm or less, and a more preferable number of crimps is 10 pieces / 25 mm or more and 20 pieces / 25 mm or less. Further, the second core-sheath type composite fiber has a crimp ratio of 5% or more and 20% or less from the viewpoint of the card-passability of the composite fiber and the tactile sensation and bulk recovery of the non-woven fabric containing the second core-sheath type composite fiber. It is preferably 6% or more and 18% or less, and more preferably 6.5% or more and 16% or less.

The fiber length of the second core-sheath type composite fiber is not particularly limited, and may be, for example, 76 mm or less. From the viewpoint of processability when producing a non-woven fabric for absorbent articles, the fiber length is preferably 30 mm or more and 65 mm or less, more preferably 40 mm or more and 60 mm or less, and further preferably 44 mm or more and 55 mm or less.

<Second fiber treatment agent>
The second fiber treatment agent is a component B composed of a polyoxyalkylene branched alkyl ether phosphoric acid ester salt having 6 or more and 9 or less carbon atoms in the alkyl chain, and a linear alkyl having 6 or more and 22 or less carbon atoms in the alkyl chain. It contains a component C composed of a phosphoric acid ester salt. Due to the attachment of the second fiber treatment agent containing the polyoxyalkylene branched alkyl ether phosphoric acid ester salt having 6 or more and 9 or less carbon atoms in the alkyl chain, the liquid absorbency of the second core-sheath type composite fiber and the liquid absorption property of the second core-sheath type composite fiber Good card passability.

In the second fiber treatment agent, component B preferably contains a phosphoric acid monoester salt and / or a phosphoric acid diester salt represented by the following general formula (II) as a main component and contains the largest amount of phosphoric acid monoester salt. .. In addition to these, the component B may contain a polyphosphate or the like. Component B is typically a mixture of these.

In the above general formula (II), R ^b represents a branched alkyl group, AO represents an oxyalkylene group (A is an alkylene moiety), M represents a cation, m is the average number of moles of polyoxyalkylene added, and n is 1 or Indicates an integer of 2. ^{When there are a plurality of R b} and M in each equation, each of them may be the same or different from each other. The AOs may be the same or different from each other.

When the number of carbon atoms of the branched alkyl group in the component B is 9 or less, it becomes easy to impart antistatic property, card-passability and hydrophilicity. Further, in the component B, when the number of branched alkyl groups is 6 or more, it becomes easy to repeatedly impart water permeability.

Examples of the branched alkyl group include an alkyl group having one or more branched chains, for example, one or two branched chains in the main chain. The form of branching is not particularly limited, and includes branching forms represented by iso, sec, neo, and tert. Specific examples thereof include an isohexyl group such as a 2-methylheptyl group and an isooctyl group such as a 2-ethylhexyl group. The branched higher alcohol that is the raw material of component B is an alcohol having a branched structure (oxo alcohol) obtained by a hydroformylation reaction of an olefin, or an alcohol having a branched structure at the β position obtained by bimolecular condensation by a Gerve reaction (an alcohol having a branched structure at the β position). Gervealcohol) is commercially available, and it is preferable to use these, and the side chains of any of the branched higher alcohols may be linear or branched.

In the component B, the oxyalkylene group preferably has 2 or more and 4 or less carbon atoms, more preferably 2 or more and 3 or less carbon atoms, and further preferably 2 or less carbon atoms. Among them, each may be the same or different from each other. It is preferable that the entire oxyalkylene group contains an oxyethylene group. Among them, those in which all oxyalkylene groups consist only of oxyethylene groups or those in which oxyethylene groups and oxypropylene groups are mixed are more preferable, and those in which all oxyalkylene groups consist only of oxyethylene groups are further preferable. .. When a plurality of types having different carbon atoms are mixed in the oxyalkylene group, for example, when an oxyethylene group and an oxypropylene group are mixed, these may be mixed randomly or may be mixed in a block shape. You may.

In the component B, the average number of moles of polyoxyalkylene added is not particularly limited, but is preferably 1 or more from the viewpoint of repeatedly imparting water permeability. From the viewpoint of antistatic property, card passability and hydrophilicity, 20 or less is preferable, 18 or less is more preferable, 15 or less is further preferable, 10 or less is particularly preferable, and 7 or less is most preferable.

In the component B, the cation M is not particularly limited, and examples thereof include hydrogen, alkali metals, alkaline earth metals, magnesium, and organic ammonium. Examples of the alkali metal include lithium, sodium, potassium and the like. Examples of the alkaline earth metal include calcium and the like. Examples of the organic ammonium include those represented by ^{NR 1} R ² R ³ R ^4. Here, R ^{1 to} R ⁴ independently represent a hydrogen atom, an alkyl group, a hydroxyalkyl group, and a polyalkylene glycol group, respectively. Among these, any alkali metal selected from sodium and potassium, ammonium, and organic ammonium having an alkyl group or hydroxyalkyl group having 20 or less carbon atoms, preferably 10 or less, and more preferably 5 or less carbon atoms are preferable.

Examples of component B include polyoxyethylene 2-methylheptyl ether phosphate ester salts (POE (1) to POE (20)) and polyoxyethylene 2-ethylhexyl ether phosphate ester salts (POE (1) to POE). (20)) and the like. The numbers in parentheses indicate the number of polyoxyethylene (POE) units.

In the second fiber treatment agent, the content of the component B is 30% by mass or more and 35% by mass or less. When the content of the component B is 30% by mass or more, it becomes easy to repeatedly impart water permeability and antistatic property. Further, when the content of the component B is 35% by mass or less, the solubility and handleability are improved.

In addition to the component B, the second fiber treatment agent contains 13% by mass or more and 23% by mass or less of the component C composed of a linear alkyl phosphate ester salt having 6 or more and 22 or less carbon atoms in the alkyl chain. By including the component C, the water permeability becomes better repeatedly.

The component C is preferably composed mainly of a phosphoric acid monoester salt and / or a phosphoric acid diester salt represented by the following general formula (III) and containing the largest amount of phosphoric acid monoester salt. In addition to these, the component C may contain a polyphosphate or the like. Component C is typically a mixture of these.

In the above general formula (III), R ^c represents a linear alkyl group, M represents a cation, and n represents an integer of 1 or 2. When ^{there are a plurality of R c} and M, each of them may be the same or different from each other.

Among them, when the second fiber treatment agent contains the component c1 having 16 or more and 22 or less carbon atoms of the alkyl group as the component C, the hydrophobic alkyl group has a larger carbon number, so that the water permeability is particularly repetitive. It will be better.

In the component C, examples of the alkyl group include a butyl group, a hexyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group (lauryl group), a tridecyl group, a tetradecyl group, a pentadecyl group, and a hexadecyl group. Examples thereof include a putadecyl group, an octadecyl group (stearyl group), a nonadecil group, an icosyl group, a henicosyl group, a docosyl group and the like. The component C may be a mixture of compounds having different alkyl groups from each other, and in this case, the carbon number of the alkyl group is the average carbon number.

The cation M in the component C is not particularly limited, and examples thereof include hydrogen, alkali metals, alkaline earth metals, magnesium, and organic ammonium. Examples of the alkali metal include lithium, sodium, potassium and the like. Examples of the alkaline earth metal include calcium and the like. Examples of the organic ammonium include those represented by ^{NR 1} R ² R ³ R ^4. Here, R ^{1 to} R ⁴ independently represent a hydrogen atom, an alkyl group, a hydroxyalkyl group, and a polyalkylene glycol group, respectively. Among these, any alkali metal selected from sodium and potassium, ammonium, and organic ammonium having an alkyl group or hydroxyalkyl group having 20 or less carbon atoms, preferably 10 or less, and more preferably 5 or less carbon atoms are preferable.

Examples of the linear alkyl phosphate ester salt of component C include hexyl phosphate ester salt, octyl phosphate ester salt, decyl phosphate ester salt, dodecyl phosphate ester salt (lauryl phosphate ester salt), tridecyl phosphate ester salt, and tetra. Examples thereof include decyl phosphate ester salt (myristyl phosphate ester salt), hexadecyl phosphate ester salt (cetyl phosphate ester salt), octadecyl phosphate ester salt (stearyl phosphate ester salt) and the like.

The method for producing component B and component C in the second fiber treatment agent is not particularly limited, but a method of neutralizing with an alkaline substance after a solvent-free reaction of an alkyl alcohol having a corresponding alkyl group and diphosphorus pentoxide. Therefore, the desired compound can be easily obtained. When this method is used, the reaction molar ratio of the alkyl alcohol having the corresponding alkyl group to diphosphorus pentoxide [(the degree of phosphoric acid) = the number of moles of the alkyl alcohol having the corresponding alkyl group / the number of moles of diphosphorus pentoxide ], The amount of phosphoric acid monoester salt produced changes, but the degree of phosphorus is 2.0 or more and 3.0 or less from the viewpoint of card-passability, hydrophilicity, and antistatic property of the first core-sheath composite short fiber. Is preferable, and 2.2 or more and 2.8 or less is more preferable.

In the second fiber treatment agent, the mass ratio C / B of the component B to the component C is preferably 3 or less, more preferably 3 or less, from the viewpoint of improving the hydrophilicity and permeability of the component B and the repeated water permeability of the component C. Is 2 or less. In the second fiber treatment agent, the mass ratio c1 / B of the component c1 and the component B is 0.01 or more and 0.40 from the viewpoint of improving the hydrophilicity and permeability of the component B and the repeated water permeability of the component c1. The following is preferable, 0.01 or more and 0.30 or less is more preferable, and 0.01 or more and 0.20 or less is further preferable.

In the solid content of the second fiber treatment agent, the total content of the component B and the component C is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, and particularly preferably 90% by mass or more. It is preferable, and 95% by mass or more is most preferable.

In addition to component B and component C, the second fiber treatment agent may contain other components as long as the effects of the present invention are not impaired. Other ingredients include, for example, surfactants, hydrophilic silicone resins, penetrants, smoothing agents, antibacterial agents, antioxidants, preservatives, matting agents, pigments, antiseptic agents, fragrances, defoaming agents, etc. Examples include fragrances, pH adjusters, viscosity adjusters and the like.

Examples of the surfactant include nonionic surfactants such as polyoxyalkylene alkyl ether, polyoxyalkylene alkenyl ether, polyoxyalkylene fatty acid ester, and fatty acid alkanolamide, alpha olephine sulfonate and alkylbenzene sulfonate, and alkyl sulfate. Anionic surfactants such as salts, polyoxyalkylene alkyl ether sulfates and sulfosuccinic acid ester salts, amphoteric surfactants such as alkyl betaine and alkyl sulfobetaines, alkyl amino fatty acid salts, and cations such as alkyl quaternary ammonium salts. Examples include surfactants.

The second fiber treatment agent contains water or a solvent for dissolving the component B and the component C, and preferably contains water. The water may be pure water, distilled water, purified water, soft water, ion-exchanged water, tap water, or the like. The ratio of the solid content (active ingredient) in the second fiber treatment agent is not particularly limited, but is preferably 5% by mass or more and 90% by mass or less, and more preferably 10% by mass or more and 80% by mass or less.

<Manufacturing method of second core sheath type composite fiber>
First, in the fiber cross section, a composite nozzle arranged so that the surface of the composite fiber is covered with a sheath component and the position of the center of gravity of the core component coincides with the position of the center of gravity of the composite fiber is a concentric structure, for example, a concentric core-sheath composite. The sheath component and the core component are supplied to the nozzle to perform melt spinning. At this time, for example, the temperature at which the core component is melted and extruded (spinning temperature) is 280 ° C. or higher and 380 ° C. or lower, and the temperature at which the sheath component is melted and extruded (spinning temperature) is 250 ° C. or higher and 350 ° C. or lower. Is melt-spun at a temperature of 250 ° C. or higher and 350 ° C. or lower.

Undrawn fiber tow by performing melt spinning in the same manner as in the case of the first core-sheath type composite fiber, except that the draft ratio is 120 or more and 600 or less, preferably 130 or more and 450 or less, more preferably 150 or more and 300 or less. Can be obtained.

Next, by stretching the undrawn fiber tow in the same manner as in the case of the first core-sheath type composite fiber, an annealing treatment is performed as necessary before and after the drawing treatment in which the drawn fiber tow can be obtained. May be good.

Next, a second fiber treatment agent is applied to the drawn fiber tow. The second fiber treatment agent can be used as an aqueous solution or an emulsion dispersion diluted with water, if necessary. For example, a treatment tank filled with an aqueous solution of a second fiber treatment agent is impregnated with a drawn fiber tow, and an excess aqueous solution of the second fiber treatment agent is squeezed out with a nip roll or the like to add a second fiber treatment agent to the drawn fiber tow. Can be granted. The second fiber treatment agent may be applied after the crimp is applied. Further, the second fiber treatment agent may be applied by means such as spraying in addition to the dipping method.

The second fiber treatment agent is not particularly limited, but from the viewpoint of liquid absorption and liquid return, the solid content is 0.25% by mass or more with respect to the mass of the drawn fiber tow (second core sheath type composite fiber). It is preferably added so as to be 55% by mass or less, more preferably 0.28% by mass or more and 0.50% by mass or less, and further preferably 0.30% by mass or more and 0.45% by mass or less.

なお、吸収性物品用不織布の第２繊維層から第１芯鞘型複合繊維４ｇを採集し、上述したとおりに、第２芯鞘型複合繊維の繊維処理剤の付着量を測定してもよい。 In the present invention, the amount of the fiber treatment agent attached to the second core-sheath type composite fiber can be measured by a rapid extraction method using an R-II type rapid residual fat extractor manufactured by Tokai Keiki Co., Ltd.
(1) 4 g of fibers cut to a predetermined length are applied to a card machine to form a fiber web, and the mass (W _f ) of the obtained fiber web is measured.
(2) After filling the mass-measured fiber web into a metal cylinder (inner diameter 16 mm, length 130 mm, mortar-shaped bottom with 1 mm hole at the bottom), 10 mL of methanol is added from the top. ..
(3) Methanol in which the fiber treatment agent adhering to the fiber sample is dissolved, which is dropped from the hole at the bottom, is _{received while heating an aluminum dish (mass: W 1} ) to evaporate the methanol. The mass of the aluminum dish (W ₁ ) is measured after the aluminum dish has been sufficiently dried in a dryer and before receiving methanol. After the methanol has completely evaporated, the mass (W ₂ ) of the aluminum dish on which the fiber treatment agent remains is measured.
(4) The amount of the fiber treatment agent attached to the mass of the fiber is calculated from the following formula.

In addition, 4 g of the first core-sheath type composite fiber may be collected from the second fiber layer of the non-woven fabric for absorbent articles, and the amount of the fiber treatment agent attached to the second core-sheath type composite fiber may be measured as described above. ..

Next, crimping can be applied to the drawn fiber tow using a known crimping machine such as a stuffing box type crimper.

The number of crimps is not particularly limited, but it is preferable to impart crimps so as to be 5 pieces / 25 mm or more and 28 pieces / 25 mm or less, more preferably 8 pieces / 25 mm or more and 25 pieces / 25 mm or less, and 10 pieces. It is particularly preferable that the number is / 25 mm or more and 20 pieces / 25 mm or less. The crimp shape after passing through the crimping machine is not particularly limited, but it is preferable that at least one crimp shape selected from serrated crimp and wavy crimp is expressed.

Further, it is preferable to perform an annealing treatment after applying crimping with the crimping machine. The annealing treatment is preferably performed in a temperature range of 80 ° C. or higher and 120 ° C. or lower in an atmosphere such as dry heat, moist heat, or steam heat, and more preferably in a temperature range of 90 ° C. or higher and 120 ° C. or lower. Specifically, it is preferable that the drawn fiber tow that has been crimped by a crimping machine is dried at the same time as the annealing treatment in a dry heat atmosphere of 90 ° C. or higher and 120 ° C. or lower because the process can be simplified.

The single fiber fineness of the second core-sheath type composite fiber can be adjusted as desired by adjusting the single fiber fineness and the draw ratio of the undrawn fiber tow. After the annealing treatment described above, the drawn fiber toe is cut to obtain a second core-sheath type composite fiber having a predetermined length.

(Non-woven fabric for absorbent articles)
In the non-woven fabric for absorbent articles, at least a part of the first core-sheath type composite fiber and the second core-sheath type composite fiber is heat-bonded by the sheath component of the first core-sheath type composite fiber and the second core-sheath type composite fiber. ing. The first fiber web containing 50% by mass or more of the first core-sheath type composite fiber and the second fiber web containing 50% by mass or more of the second core-sheath type composite fiber are laminated, and the fiber web having a laminated structure is heat-treated. At least a part of the first core-sheath type composite fiber and the second core-sheath type composite fiber is heat-bonded by the sheath component.

Examples of the textile web include a parallel web, a semi-random web, a random web, a cross web, a card web such as criss cross web, and an air raid web. Since the non-woven fabric for absorbent articles is required to have bulkiness, flexibility, a certain amount of porosity between fibers, and an appropriate porosity, the fiber web is preferably a card web. The first fiber layer and the second fiber layer may be different types of fiber webs.

The fiber web of the laminated structure is heat-treated, and the first core-sheath type composite fiber and the second core-sheath type composite fiber are heat-bonded by the sheath component of the first core-sheath type composite fiber and the second core-sheath type composite fiber. Therefore, the non-woven fabric for absorbent articles of the present invention can be obtained in the form of a heat-bonded non-woven fabric containing the first fiber layer (first fiber web) and the second fiber layer (second fiber web). This is because, in the form of the heat-bonded non-woven fabric, the effects such as flexibility in the thickness direction, bulk recovery, and smooth texture of the non-woven fabric surface are remarkably exhibited. In order to entangle the fibers, the fiber web may be subjected to an entanglement treatment such as a needle punching treatment or a water flow entanglement treatment before and / or after the heat treatment, if necessary. The first fiber web and the second fiber web may be intertwined with each other near the boundary.

The above heat treatment can be performed by a known heat treatment machine. For example, for the heat treatment, a heat treatment machine such as a hot air penetration type heat treatment machine, a hot air blowing type heat treatment machine, and an infrared heat treatment machine in which pressure such as wind pressure is not so much applied to the fiber web is preferably used. The heat treatment conditions such as the heat treatment temperature are selected and carried out so that, for example, the sheath components are sufficiently melted and / or softened so that the fibers are joined at the contact points or intersections and the crimps are not crushed. For example, the heat treatment temperature is Tm, which is the melting point of the high-density polyethylene contained in the sheath component before spinning (when a plurality of high-density polyethylenes are contained in the sheath component, the melting point of the high-density polyethylene having the highest melting point). It is preferable that the temperature is in the range of Tm or more and (Tm + 40 ° C.) or less. The more preferable range of the heat treatment temperature is (Tm + 5 ° C.) or more and (Tm + 30 ° C.) or less.

In the above-mentioned non-woven fabric for absorbent articles, the texture of the first fiber layer ^{is preferably 4 g / m 2} or more and 18 g / m ² or less, preferably 5 g / m ^{2 from the viewpoint of less liquid return and excellent wet back resistance.} It is more preferably 18 g / m ² or more, more preferably 6 g / m ² or more and 15 g / m ² or less, and particularly preferably 7 g / m ² or more and 14 g / m ² or less. Further, from the viewpoint of less liquid return and excellent wetback resistance, the basis weight of the second fiber layer ^{is preferably 6 g / m 2} or more and 30 g / m ² or less, and 8 g / m ² or more and 28 g / m ² or less. More preferably, it is more preferably 10 g / m ² or more and 25 g / m ² or less. In the above-mentioned non-woven fabric for absorbent articles, the basis weight of the first fiber layer is preferably smaller than the basis weight of the second fiber layer from the viewpoint of less liquid return and excellent wetback resistance.

In the above-mentioned non-woven fabric for absorbent articles, the first fiber layer comes into contact with the skin of the wearer who wears the absorbent articles. When the first fiber layer containing the first core-sheath type composite fiber comes into contact with the skin, it is possible to give a comfortable feeling to the user of the absorbent article. The above-mentioned non-woven fabric for absorbent articles is the surface of various absorbent articles such as sanitary napkins, infant paper diapers, adult paper diapers, paper diapers for animals such as mammals, panty liner (pantyliner), and incontinence liner. It can be preferably used as a sheet.

The absorbent article of the present invention is not particularly limited as long as it contains the above-mentioned non-woven fabric for absorbent articles. 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. However, the present invention is not limited to these examples.

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

(Melting point of high density polyethylene)
For the melting point of the high-density polyethylene, the melting peak temperature measured according to JIS K 7121 (1987) was used as the melting point of the high-density polyethylene.

(Melt mass flow rate of high density polyethylene (MFR190))
The melt mass flow rate (MFR190) of high-density polyethylene was measured under the measurement conditions of a measurement temperature of 190 ° C. and a load of 2.16 kg (21.82 N) according to JIS K 7210-1 (2014).

(Intrinsic viscosity of polyester resin)
The intrinsic viscosity (extreme viscosity) of the polyester resin was measured according to JIS K 7376-5 (2000). Specifically, 1 g of polyethylene terephthalate is dissolved in 100 mL of a mixed solvent in which phenol and 1,1,2,2-tetrachloroethane have a mass ratio (phenol / 1,1,2,2-tetrachloroethane) of 6/4. Then, it was measured at 30 ° C. using a Ubbelohde viscometer.

(Measurement of molecular weight distribution of polyester resin)
The number average molecular weight (Mn), weight average molecular weight (Mw), z average molecular weight (Mz), and Q value (Mw / Mn), which is the ratio of Mw to Mn, of the polyester resin are measured by gel permeation chromatography (GPC). bottom. For the measurement, a gel permeation chromatograph device equipped with a differential refractive index detector RI was used as a detector.

As a sample used for the measurement, a composite fiber after spinning was prepared. 50 mg of the composite fiber was freeze-milled using liquid nitrogen, and the sample was collected with a 0.45 μm membrane filter and sufficiently dried. Next, 3 mg of the dried sample was weighed, 2.5 mL of a measurement solvent (hexafluoroisopropanol added with sodium trifluoroacetate so as to be 5 mM: HFIP) was added to this sample, and the mixture was stirred at room temperature. At this time, the sheath component (high-density polyethylene) of the composite fiber that is insoluble in hexafluoroisopropanol and the added inorganic filler are generated as insoluble matter. After sufficiently stirring to dissolve the polyester resin, filtration was performed with a 0.45 μm membrane filter to obtain a sample solution for measurement. The obtained sample solution for measurement was injected into a gel permeation chromatograph device under the conditions of a flow velocity of 0.2 mL / min and an injection amount of 0.02 mL / min to obtain a number average molecular weight (Mn) and a weight average molecular weight (Mw). ), The z average molecular weight (Mz) was measured. When measuring, one Shodex (Shodex is a registered trademark) HFIP-G manufactured by Showa Denko KK and two Shodex (Shodex is a registered trademark) HFIP-606M manufactured by Showa Denko KK were used as columns, and monodisperse polymethyl was used. The molecular weight was calibrated using methacrylate as a standard sample.

(High-density polyethylene crystallite size)
The crystallite size of high-density polyethylene contained in the sheath component of the composite fiber was calculated by Scherrer's formula (Formula 1) from the obtained diffraction peaks by performing wide-angle X-ray diffraction method by the following method.

The composite fiber was cut to a length of 2.5 cm. The cut sample was weighed at 12.5 mg, and the sample was obtained by binding both ends with an enamel wire. A fiber bundle as a sample was fixed to a holder so as to be perpendicular to the incident direction of X-rays, and wide-angle X-ray diffraction was performed. The measurement conditions are as follows.

X-ray diffractometer: Smart Lab (registered trademark) for polymers manufactured by Rigaku Co., Ltd.
X-ray source: CuKα ray (using Ni filter)
Output: 40kV 50mA
Slit system: RS1: 15mm RS2: 20mm
Measurement direction: Fiber radial direction scan Scan method: Continuous scan Measurement range: 2θ = 10-40 °
Step: 0.05 °
Scan speed: 2 ° / min

λ（入射Ｘ線波長）：０．１５４１８ｎｍ
β₀（半値幅の補正値）：０．４６°
Ｋ（Ｓｃｈｅｒｒｅｒ定数）：０．９ Further, from the half width of the obtained X-ray diffraction peak, the crystallite size was calculated by the following formula 1 (Scherrer's formula). In Equation 1, λ, β ₀ , and K are as follows.

λ (incident X-ray wavelength): 0.15418 nm
β ₀ (correction value of half width): 0.46 °
K (Scherrer constant): 0.9

(Measurement of heat of fusion (ΔH _{PE-HD) of high-density polyethylene)
For the heat of fusion (ΔH PE-HD} ) of high-density polyethylene contained in the sheath component of the composite fiber, the transition temperature of the plastic is measured by the following procedure, and the heat absorption peak temperature exists in the temperature range of 125 ° C to 140 ° C. The composite fiber contains the amount of heat of fusion (ΔH) of the peak (heat absorption due to melting is observed from about 120 ° C., the melting peak temperature is reached from 125 ° C. to 140 ° C., and heat absorption due to melting ends at about 150 ° C.). It was calculated by converting it to the amount of heat of melting (ΔH _{PE-HD) of the high-density polyethylene.}

First, the core-sheath ratio (volume ratio) is based on the density and addition amount of the core component, the thermoplastic resin constituting the sheath component, and the inorganic filler with respect to the core-sheath ratio (volume ratio) for determining the heat of fusion of the high-density polyethylene. ) Was converted to the core-sheath ratio (mass ratio), and the ratio of high-density polyethylene to the composite fibers (mass ratio of high-density polyethylene) was determined from the ratio of the inorganic filler contained in the sheath component. Next, the differential scanning calorimetry was performed on the composite fiber as a sample based on the transition temperature measurement method of JIS K 7121 (1987) plastic. The differential scanning calorimetry was measured using a differential scanning calorimeter (trade name "EXSTAR6000 / DSC6200" manufactured by Seiko Instruments Inc.). By differential scanning calorimetry, the endothermic process associated with the melting of the composite fiber was observed from about 120 ° C., the melting peak temperature was reached from 125 ° C. to 140 ° C., and the endothermic process associated with the melting of the high-density polyethylene was completed at about 150 ° C. The amount of heat of fusion (ΔH) was measured for the endothermic peak observed in the range of about 120 ° C. to about 150 ° C. From the heat of fusion (ΔH) measured between about 120 ° C. and about 150 ° C., the heat of fusion (ΔH _PE-HD ) of the high-density polyethylene contained in the composite fiber was calculated by the following mathematical formula 2.

(Number of crimps and crimp rate)
It was measured according to JIS L 1015 (2010).

(Single fiber strength and elongation at break)
The single fiber strength and breaking elongation of the composite fiber were measured by measuring the single fiber strength (tensile strength) and breaking elongation (elongation rate) according to JIS L 1015 (2010) 8.7 tensile strength and elongation. The ratio of single fiber strength to breaking elongation (single fiber strength / breaking elongation) and the product of single fiber strength to the positive square root of breaking elongation (single fiber strength x √ breaking elongation) is JIS L 1015 (2010). It was calculated from the strength of single fiber and the elongation at break measured according to (year).

(Single fiber fineness and fiber length of composite fiber)
The single fiber fineness of the composite fiber was measured according to JIS L 1015 (2010) 8.5 (vibration method). The fiber length of the composite fiber was measured according to JIS L 1015 (2010) 8.4.

(Core-sheath ratio (volume ratio) of composite fiber)
First, the cross section of the composite fiber for which the core-sheath ratio is measured was photographed by magnifying it 500 to 2500 times using a scanning electron microscope (SEM). At this time, when the photographed photograph was printed, the magnification was adjusted so that the diameter of one printed composite fiber was 5 to 8 cm, and the photograph was observed and photographed. Only the image of the core-sheath type composite fiber was cut out from the obtained scanning electron microscope photograph. The image of the cut-out core-sheath type composite fiber was cut along the boundary between the core component and the sheath component, and the core component portion and the sheath component were cut. This work was performed on 20 fibers, and the total mass of only the core component cut out from the 20 core-sheath type composite fibers was measured with an electronic balance. Similarly, for the sheath component, the total mass of only the sheath component cut out from the above 20 core-sheath type composite fibers was measured with an electronic balance. The ratio (core / sheath) of the total mass of the portion containing only the core component and the total mass of the portion containing only the sheath component was defined as the core-sheath ratio (volume ratio).

上記数式４において
Ｖｓ：引き取り速度（ｃｍ／分）
ｄ：ホール径（ｃｍ）
Ｗ_h：単孔あたりの樹脂吐出量（ｇ／分）
なお、溶融比重は芯成分及び鞘成分の溶融時の比重であり、溶融紡糸時と同じ温度に設定された押出機から一定体積の溶融樹脂を押し出し、押し出された樹脂の質量を測定し、押し出された樹脂の質量を上記一定体積で除することで測定した。 (Draft ratio)
The draft ratio was calculated by the following formula 4.

In the above formula 4, Vs: pick-up speed (cm / min)
d: Hole diameter (cm)
W _h : Resin discharge amount per single hole (g / min)
The melt specific gravity is the specific gravity when the core component and the sheath component are melted, and a certain volume of molten resin is extruded from an extruder set to the same temperature as during melt spinning, and the mass of the extruded resin is measured and extruded. It was measured by dividing the mass of the resin obtained by the above constant volume.

(Card passability)
The card passability of the composite fiber was evaluated according to the following criteria based on the occurrence of neps and flies when the fiber web was produced using a card machine, and the texture of the obtained fiber web.
++: Since the fibers easily pass through the card machine and almost no neps or flies are generated, a fiber web with a good texture can be obtained.
+: Some neps are generated, but it does not affect the texture of the fiber web so much.
-: Fiber web cannot be obtained due to poor card passage or a large amount of neps.

(Liquid absorption rate and liquid return amount)
(1) The following articles were prepared in order to measure the liquid absorption rate and the liquid return amount.
Absorber: The top sheet of the commercially available Kao Corporation "Relief Paper Pants Pad Reliable Fit" was used as the absorber.
Saline filter paper: manufactured by Toyo Filter Paper Co., Ltd., ADVANTEC (registered trademark) No. 2, 10 cm x 10 cm
Weight: 5 kg
Liquid absorbing cylinder: inner diameter 40 mm, total weight 1125 g, lower part 9 cm x 9 cm
(2) Method The liquid absorption rate and the amount of liquid return were measured according to the following procedure.
(I) A non-woven fabric ((vertical direction (mechanical direction) 30 cm, horizontal direction 15 cm) was placed on the absorber.
(Ii) A liquid absorbing cylinder was placed in the center of the set non-woven fabric, and 150 g of physiological saline heated to 37 ° C. was poured from the upper part of the liquid absorbing cylinder. After pouring the saline solution, the saline solution disappears from the surface of the non-woven fabric (the saline solution moves from the non-woven fabric to the absorber located under the non-woven fabric, and the saline solution is not confirmed as a liquid on the surface of the non-woven fabric). Time to time was measured using a stopwatch.
(Iii) Ten minutes after pouring the saline solution, the liquid absorbing cylinder is removed, and a filter paper (ADVANTEC® No. 2 manufactured by Toyo Filter Paper Co., Ltd.) whose mass has been measured in advance is placed on the non-woven fabric. A 5 kg weight was placed on the filter paper for 20 seconds. After 20 seconds, the filter paper was taken out, the mass of the filter paper that had absorbed the physiological saline was measured, and the mass of the filter paper before being placed on the non-woven fabric was subtracted to calculate the amount of liquid return.

The polyethylene terephthalate (PET) and high-density polyethylene (PE-HD) used in Examples and Comparative Examples are as follows.
(1) PET (commercially available polyethylene terephthalate having a melting point: 255 ° C. and an intrinsic viscosity: 0.64)
(2) PE-HD1 (melting point: 133 ° C., density ^{: 0.956 g / cm 3} , MFR190: 22 g / 10 min, high-density polyethylene, manufactured by Japan Polyethylene Corporation, product name "Novatec (registered trademark) HE490")
(3) PE-HD2 (melting point: 133 ° C., density: 0.956 ^{g / cm 3} , MFR190: 13 g / 10 min, high-density polyethylene, manufactured by Japan Polyethylene Corporation, product number "Novatec (registered trademark) HE481")

As the first fiber treatment agent, one having the composition shown in Table 1 below was used.

A second fiber treatment agent having the composition shown in Table 4 below was used. In the second fiber treatment agent, the component B shown in Table 2 below was used, and the component C shown in Table 3 below was used.

(Manufacturing Example 1)
PET was used as a core component and PE-HD1 was used as a sheath component. For the prepared sheath component and core component, use a concentric core-sheath type composite nozzle, and adjust the discharge amount of each component so that the composite ratio (volume ratio) of the sheath component and the core component is core / sheath = 37/63. The melt spinning was carried out under the conditions shown in Table 5 below. The extruded molten filament was taken up so as to have the draft ratio shown in Table 5 below to obtain an undrawn fiber tow having a single fiber fineness shown in Table 5.

The obtained unstretched fiber tow was wet-stretched in hot water at 80 ° C. at the draw ratio shown in Table 5 to obtain a stretched fiber tow. Next, the treatment tank filled with an aqueous solution of the first fiber treatment agent (an aqueous solution having an active ingredient concentration of 5% by mass) is impregnated with the drawn fiber tow, and then an excess aqueous solution of the first fiber treatment agent is applied to a resin roll ( By squeezing with a nip roll), the water content was adjusted so that the active component (solid content) of the first fiber treatment agent was 0.40% by mass with respect to the mass of the drawn fiber tow (composite fiber).

In the example, the tow heat treatment was performed on the drawn fiber tow to which the fiber treatment agent was applied. The tow heat treatment was carried out by putting the drawn fiber tow in a tension state of 1.0 times and spraying steam set at 100 ° C. on the drawn fiber toe for 3 seconds.

Toe The heat-treated drawn fiber tow was mechanically crimped with a stuffing box type crimper. At this time, the temperature of the surface of the drawn fiber toe immediately before entering the inside of the stuffing box type crimper was measured and found to be 85 ° C. Further, the temperature of the surface of the drawn fiber toe immediately after coming out from the inside of the stuffing box type crimper was measured and found to be 70 ° C. Then, the annealing treatment and the drying treatment were simultaneously performed in a relaxed state for 15 minutes with a hot air blowing device set at 110 ° C. Then, the drawn fiber tow was cut to a predetermined length shown in Table 5 below to obtain a composite fiber 1.

(Manufacturing Example 2)
The composite fiber 2 was produced in the same manner as in Production Example 1 except that the second fiber treatment agent was used as the fiber treatment agent.

(Manufacturing Example 3)
PET was used as a core component and PE-HD2 was used as a sheath component. Using a concentric concentric sheath type composite nozzle, the prepared sheath component and core component are discharged so that the composite ratio (volume ratio) of the sheath component and the core component is the composite ratio of core / sheath = 37/63. Was adjusted and melt spinning was performed. The spinning temperature of the sheath component is 270 ° C, the spinning temperature of the core component is 340 ° C, the nozzle temperature is 290 ° C, and the extruded molten filament is taken up so as to have a draft ratio of 226. I got a toe.

The obtained undrawn fiber tow was wet-stretched in hot water at 80 ° C. at a draw ratio of 2.9 times to obtain a drawn fiber tow having a single fiber fineness of about 4.4 dtex. Next, the treatment tank filled with an aqueous solution of the second fiber treatment agent (an aqueous solution having an active ingredient concentration of 5% by mass) is impregnated with the drawn fiber tow, and then an excess aqueous solution of the fiber treatment agent 2 is applied to a resin roll (nip roll). ), The water content was adjusted so that the active component (solid content) of the second fiber treatment agent was 0.35% by mass with respect to the mass of the drawn fiber tow (composite fiber).

Next, mechanical crimping was applied with a stuffing box type crimper, and an annealing treatment and a drying treatment were simultaneously performed in a relaxed state for 15 minutes with a hot air blowing device set at 110 ° C. Then, the drawn fiber tow was cut to 51 mm to obtain a composite fiber 3.

(Example 1)
First, using the composite fiber 1 obtained in Production Example 1, a first fiber web having the following ^{basis weight of 8 g / m 2 was produced by a roller-type card machine.} Next, using the composite fiber 3 obtained in Production Example 3, a second fiber web having a ^{basis weight of 12 g / m 2 was produced by a roller-type card machine.} Next, after laminating the second fiber web on the first fiber web, the obtained laminated fiber web is heat-treated for 15 seconds using a hot air penetrating heat treatment machine set at 135 ° C., and the composite fiber 1 and the composite fiber are heat-treated. The sheath component in No. 3 was melted and the composite fiber 1 and the composite fiber 3 were heat-bonded to obtain a heat-bonded non-woven fabric containing the first fiber layer and the second fiber layer (grain 20.0 g / m ² ). At this time, the laminated fiber web is heat-treated with the first fiber web, which is the first fiber layer, in contact with the conveyor net surface of the hot air penetrating heat treatment machine, and the hot air is applied to the laminated fiber web from the second fiber layer side. I sprayed it.

(Example 2)
Except that the both basis weight of the first fibrous web and the second fibrous web 10 g / m ^2, to obtain a thermal bonding nonwoven fabric in the same manner as in Example 1 (basis weight 20.0 g / m ^2).

(Comparative Example 1)
^{A heat-bonded nonwoven fabric (grain 20.0 g / m 2} ) was obtained in the same manner as in Example 1 except that the composite fiber 2 was used instead of the composite fiber 1.

The liquid absorption rate and the amount of liquid return of the heat-bonded nonwoven fabrics of Examples and Comparative Examples were evaluated as described above, and the results are shown in Table 6 below.

As can be seen from the data in Table 6, the non-woven fabrics of Examples 1 and 2 had a smaller amount of liquid return than the non-woven fabric of Comparative Example 1, and the liquid return was reduced. In addition, the non-woven fabric for absorbent articles of the examples had a smooth touch and an excellent texture.

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 preferably used as a surface sheet of.

1 Non-woven fabric for absorbent articles 2, 3 Core sheath type composite fiber 11 1st fiber layer 12 2nd fiber layer 21, 31 Sheath component 22, 32 Core component 23, 33 Center of gravity position of core component in fiber cross section 24, 34 Core sheath Position of the center of gravity in the fiber cross section of the type composite fiber 25, 35 Radius in the fiber cross section of the core-sheath type composite fiber

Claims (2)

A non-woven fabric for an absorbent article containing a first fiber layer in contact with the skin and a second fiber layer adjacent to the first fiber layer.
The first fiber layer contains 60% by mass or more of a polyester resin as a core component, 60% by mass or more of a thermoplastic resin having a sheath component having a melting point of 50 ° C. or more lower than the melting point of the polyester resin, and has a single fiber fineness of 0. A fiber layer containing 50% by mass or more of the first core-sheath type composite fiber having a thickness of .5 dtex or more and 2.1 dtex or less.
The second fiber layer contains 60% by mass or more of a polyester resin as a core component, 60% by mass or more of a thermoplastic resin having a sheath component having a melting point of 50 ° C. or more lower than the melting point of the polyester resin, and has a single fiber fineness of 2. It is a fiber layer containing 50% by mass or more of the second core-sheath type composite fiber having .2 dtex or more and 7.0 dtex or less.
The first fiber treatment agent is adhered to the surface of the first core-sheath type composite fiber.
A second fiber treatment agent is attached to the surface of the second core-sheath type composite fiber.
The first fiber treatment agent contains a component A composed of a linear alkyl phosphate ester salt having 6 or more and 22 or less carbon atoms in the alkyl chain, and the component A is a component having 16 carbon atoms in at least one alkyl group. a1, a component a2 having at least one alkyl group having 18 carbon atoms, and a component a3 having at least one alkyl group having 10 or less carbon atoms, and the mass ratio a1 / a2 of the component a1 and the component a2 is 1.0 or more. It is 3.4 or less, the mass ratio a3 / (a1 + a2) of the component a3 to the total mass of the component a1 and the component a2 is 3.0 or less, and the total content of the component a1 and the component a2 in the first fiber treatment agent. Is 7% by mass or more and 12% by mass or less,
The second fiber treatment agent is a component B composed of a polyoxyalkylene branched alkyl ether phosphoric acid ester salt having 6 or more and 9 or less carbon atoms in the alkyl chain, and a linear alkyl phosphorus having 6 or more and 22 or less carbon atoms in the alkyl chain. It contains a component C composed of an acid ester salt, and the content of the component B in the second fiber treatment agent is 30% by mass or more and 35% by mass or less, and the content of the component C is 13% by mass or more and 23% by mass or less.
At least a part of the first core-sheath type composite fiber and the second core-sheath type composite fiber is thermally adhered to the first core-sheath type composite fiber by the sheath component of the second core-sheath type composite fiber. Nonwoven fabric for absorbent articles, characterized by. An absorbent article comprising the non-woven fabric for an absorbent article according to claim 1 as a surface sheet and in which the first fiber layer is arranged so as to come into contact with the skin.

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