JP7516205B2 - Nonwoven - Google Patents

Description

The present invention relates to nonwoven fabrics.

Nonwoven fabrics are often used in absorbent articles such as diapers. Technologies have been developed to give nonwoven fabrics various functions.

For example, Patent Document 1 describes incorporating a resin-bonded nonwoven fabric impregnated or coated with an adhesive into an absorbent article in order to improve the thickness recovery of the absorbent article. Specifically, the resin-bonded nonwoven fabric is disposed as a component of the absorbent article that does not come into contact with the skin.

JP 2001-187088 A

Among conventional nonwoven fabrics, there are some that have been made thicker than their basis weight by providing unevenness in the thickness direction, i.e., have a thick apparent thickness between the front and back surfaces. Such nonwoven fabrics tend to be soft to the touch and have a fluffy texture.
On the other hand, in the above-mentioned nonwoven fabric, when it comes into contact with the skin, depending on the degree of friction, fluff may come off. The fluff may become pilling. In particular, in the case of a nonwoven fabric in which sheet integrity is imparted by fusion points between fibers, if there are any missing fusion points, the above-mentioned fluffing or the like is likely to occur at those parts. For example, when a fiber web is formed into an uneven shape and then a fusion point is formed by hot air treatment to produce a nonwoven fabric, a support is used for the uneven shape, so that the passage of hot air is suppressed to that extent, and the above-mentioned problems are likely to occur. Such fluffing and pilling derived from the fluffing need to be suppressed from the viewpoint of the feel of the nonwoven fabric, and there is room for improvement.

In view of the above, the present invention relates to a nonwoven fabric that maintains a soft feel while suppressing shedding.

The present invention provides a nonwoven fabric having fusion points between fibers, a front surface and a back surface, an apparent thickness of 1.5 mm or more when a load of 0.05 kPa is applied from one side using a horizontal plate, the proportion of the contact area between the horizontal plate and the nonwoven fabric under a pressure of 3 kPa to the surface area of the front surface is 90% or less, the nonwoven fabric contains fibers on at least the front surface to which a polymer having a glass transition point of 10°C or less is attached, and the polymer is contained in an amount of 5% by mass to 40% by mass.

The nonwoven fabric of the present invention maintains a soft feel while reducing shedding.

1A and 1B are side views showing specific examples of the uneven shape of the nonwoven fabric of the present invention. 1 is a drawing-substitute photograph showing an enlarged view of a polymer membrane that is fixed so as to form a membrane in a minute space surrounded by fibers. FIG. 2 is a partially sectional perspective view showing a schematic diagram of specific example 1 of the uneven shape of a nonwoven fabric. 1 is a photograph showing a plane view of one side of specific example 2 of a nonwoven fabric having a concave-convex shape. 5 is a partial cross-sectional view of the nonwoven fabric shown in FIG. 4 taken along the line CC. 5 is a partial cross-sectional view of the nonwoven fabric shown in FIG. 4 along line DD. 5 is a photograph showing a plan view of the opposite side of the nonwoven fabric shown in FIG. 4 . 8 is a partial cross-sectional view of the nonwoven fabric shown in FIG. 7 taken along line E-E. 8 is a partial cross-sectional view of the nonwoven fabric shown in FIG. 7 taken along the line FF. FIG. 1 is an explanatory diagram showing a preferred embodiment of the method for producing a nonwoven fabric of the present invention, in which (A) shows a process of placing a fiber web on a male support material and pressing a female support material into the male support material from above the fiber web, (B) shows a process of pressing the female support material into the male support material to form a fiber web, (C) shows a process of removing the female support material and blowing hot air from above the shaped fiber web to fuse the fibers together, (D) shows the state of the shaped raw nonwoven fabric removed from the male support material, and (E) shows a process of spraying a polymer coating solution onto one side of the removed raw nonwoven fabric (the side that faces the skin in the case of a diaper, for example) (the side opposite to the side onto which the hot air was blown).

Preferred embodiments of the nonwoven fabric of the present invention will now be described.
The nonwoven fabric of the present invention has fusion points between fibers (fusion points at fiber intersections). The fusion points are the parts where the fibers are bonded to each other at the contact points between the intersecting fibers by fusion of the thermoplastic resin component of the fibers themselves. More specifically, the fusion points are formed by, for example, melting the surface of the thermoplastic fiber by heat treatment during the manufacturing process of the nonwoven fabric, and fusing the fibers together. Examples of the nonwoven fabric of the present invention include thermal bonded nonwoven fabrics, and more specifically, air-through nonwoven fabrics (nonwoven fabrics in which the fusion points are formed by hot air treatment. Short fibers of 60 mm or less are mainly used) and spunbonded nonwoven fabrics (nonwoven fabrics in which a resin in a molten state is spun into a nonwoven fabric as it is, and the fusion points are formed by embossing. Long fibers of 100 mm or more are mainly used). When used in contact with the skin, such as in the case of materials for absorbent articles, air-through nonwoven fabrics are preferable, especially from the viewpoint of texture.

The nonwoven fabric of the present invention has a front side (usage side) that is used according to the purpose of the article and a back side on the opposite side. The front side is the side that is subjected to friction during use.
For the sake of convenience, the following description will be given assuming that the nonwoven fabric of the present invention is used as a member such as a topsheet of an absorbent article, with the front side being the skin-facing side and the back side being the non-skin-facing side. In this specification, the skin-facing side and the non-skin-facing side refer to the side that faces the skin of the user, etc., and the opposite side thereof, when the nonwoven fabric of the present invention is used. The skin-facing side and the non-skin-facing side are defined as indicating a relative positional relationship, even if the nonwoven fabric does not directly contact the skin of the user, etc. The skin-facing side and the non-skin-facing side are the front and back sides of the nonwoven fabric, and are the side that is furthest from the horizontal plane in the vertical direction to the horizontal plane and the side that is closest to the horizontal plane when the nonwoven fabric is placed on the horizontal plane.

The nonwoven fabric of the present invention has an apparent thickness under a load of 0.05 kPa of 1.5 mm or more.
Here, the "apparent thickness" means the vertical distance between a horizontal plane and an imaginary plane (horizontal plate) that is in contact with the outermost part of the side of the nonwoven fabric opposite to the side that is in contact with the horizontal plane when the nonwoven fabric is placed on the horizontal plane (hereinafter, the vertical direction to the horizontal plane may be simply referred to as the "vertical direction"). For example, when the nonwoven fabric of the present invention has an uneven shape on both sides, the apparent thickness is the vertical distance between the position of the apex of the convexity on one side and the position of the apex of the convexity on the other side.
The "apparent thickness" means the thickness when a load of 0.05 kPa is applied from one side using a horizontal plate. Specifically, it can be measured by the following method. Here, the "load of 0.05 kPa" means a load that suppresses fuzzing on the surface of the nonwoven fabric, and is a light load (a light load that is not a compressive force that would crush the thickness of the nonwoven fabric) necessary to properly measure the apparent thickness of the nonwoven fabric. The load of 0.05 kPa is applied to the nonwoven fabric by placing a horizontal plate, for example, a circular plate with a diameter of 2.5 cm and a mass of 2.45 g, on one side of the nonwoven fabric.

(Method for measuring the apparent thickness of a nonwoven fabric under a load of 0.05 kPa)
The nonwoven fabric to be measured is cut to 10 cm x 10 cm to prepare a measurement sample. Using a laser thickness gauge (high-precision displacement sensor ZS-LD80 (product name) manufactured by Omron Corporation; all laser thickness gauges used in this specification are of this type), a load of 0.05 kPa is applied to one side of the measurement sample using a horizontal plate, and the thickness is measured in this state. Measurements are taken at three locations, and the average value is taken as the apparent thickness of the nonwoven fabric to be measured.
In addition, when the nonwoven fabric to be measured is incorporated into a product, the adhesive strength of the adhesive or the like is weakened by a cooling means such as a cold spray, and the nonwoven fabric is removed from the product and the above measurement is performed. This method of removing the nonwoven fabric is similarly applied to other measurements in this specification.
If it is not possible to take out a nonwoven fabric measuring 10 cm x 10 cm, take out a piece as large as possible.

The nonwoven fabric of the present invention has an apparent thickness of 1.5 mm or more under a load of 0.05 kPa, so that the thickness can be felt at the beginning of use. From this viewpoint, the apparent thickness is preferably 2 mm or more, and more preferably 3 mm or more. Furthermore, from the viewpoints of storage efficiency and ease of processing, the apparent thickness is preferably 12 mm or less, more preferably 10 mm or less, and even more preferably 9 mm or less.

In addition, the nonwoven fabric of the present invention has a contact area between the horizontal plate and the nonwoven fabric that accounts for 90% or less of the surface area of the skin-facing side. This contact area can be measured by applying a pressure of 3 kPa using the following method. The "surface area of the skin-facing side" refers to the area of the outline of the nonwoven fabric obtained by observing the skin-facing side of the nonwoven fabric to be measured from above. Therefore, when there are irregularities, the area of the part along the undulations is ignored.
The contact area of 90% or less means that the skin-facing side of the nonwoven fabric has an uneven shape, and crushing is suppressed under a pressure of 3 kPa as described below. Note that the pressure of 3 kPa is assumed to be the pressure applied to the back side of the diaper when the nonwoven fabric of the present invention is used as the top sheet of the diaper and a premature baby (0 years 1 month to 0 years 4 months) wearing the diaper is lying on its back. The uneven shape means a shape in which, when the nonwoven fabric is viewed in the thickness direction, a convex portion protruding in the thickness direction and a concave portion recessed are adjacent to each other, and these convex portions and concave portions are alternately arranged in the planar direction. As long as the uneven shape is on the skin-facing side of the nonwoven fabric, it may also be on the nonskin-facing side in addition to this. In other words, it is not limited to the case where only the skin-facing side of the nonwoven fabric of the present invention has an uneven shape, and both the skin-facing side and the nonskin-facing side may have an uneven shape.
From the viewpoint of improving the feel, the contact area is preferably 80% or less, and more preferably 70% or less. Also, from the viewpoint of improving the bonding strength with other members, the contact area is preferably 30% or more, more preferably 40% or more, and even more preferably 50% or more.

(Method of measuring contact area)
(1) A measurement sample measuring 50 mm x 50 mm is cut out from the nonwoven fabric.
(2) Place the measurement sample with the measurement surface facing up.
(3) Using a high-precision shape measurement system KS-1100 (product name, manufactured by Keyence Corporation), the measurement surface is irradiated with laser light to measure the surface shape (the height and depth shape of the thickness undulating along the surface direction of the measurement surface) of the measurement surface in a no-load state (natural state without load) and an image is captured. At this time, the measurement range is 1 cm ² (measurement pitch: vertical 20 μm, horizontal 20 μm), and the movement speed is 10 cm/sec.
(4) Next, a transparent acrylic plate with a mass of 170 g is placed on the measurement surface of the measurement sample, and a weight with a mass of 600 g is further placed on the acrylic plate. In this state, a pressure of 3 kPa is applied, and the surface shape of the measurement surface is measured and an image is captured in the same manner as in (3) above.
(5) The images captured in (3) and (4) above are analyzed using a shape analysis application KS-Analyzer (product name, manufactured by Keyence Corporation). Specifically, the part where the thickness changes from the no-load state to the state where a pressure of 3 kPa is applied (minimum measurable scale: 0.01 μm) is extracted and binarized to obtain a surface image of that part.
(6) The surface image of the part where the thickness has changed obtained in (3) above is imported and processed using image processing software NewQube (Ver. 4.22, product name, manufactured by Nexus Co., Ltd.), and its area is measured. This area corresponds to the area of the part that comes into contact with the skin when the nonwoven fabric of the measurement sample is pressurized with 3 kPa, i.e., the contact area.
(7) The measured area is divided by the area of the measurement sample (measurement points: 251,001 points (=501 x 501)) to calculate the "contact area ratio" of the measurement surface of the nonwoven fabric to be measured.

The nonwoven fabric of the present invention contains fibers having attached thereto a polymer having a glass transition point of 10° C. or less (hereinafter also referred to as an attachment polymer) on at least the skin-facing side. The attachment polymer is contained in an amount of 5% by mass to 40% by mass based on the mass of the nonwoven fabric (mass excluding the attachment polymer).
The attachment polymer is attached in a fixed state to the fibers constituting the nonwoven fabric, thereby increasing the adhesive strength between the fibers. Moreover, as described above, the attachment polymer has a low glass transition point, which imparts elasticity or flexibility to the fiber surface and reduces hardness, and the presence of the attachment polymer in the above content by mass ratio reduces adhesion to the skin, improving the smoothness and texture of the nonwoven fabric. The fibers to which such polymers are attached may be present inside the nonwoven fabric or on the nonskin side, as long as they are present on the skin side of the nonwoven fabric of the present invention.
The presence of the adhesion polymer acting in this way on the skin-facing side of the nonwoven fabric of the present invention suppresses shedding of fuzz in response to frictional forces applied from the skin-facing side, improving the smoothness and texture of the nonwoven fabric. In particular, when the nonwoven fabric of the present invention has an uneven shape (for example, when both sides of the nonwoven fabric 10 in FIG. 1(A) and the nonwoven fabric 20 in FIG. 1(B) have uneven shapes, or when only the skin-facing side 1A has an uneven shape (not shown)), even if frictional forces and pressure are concentrated on the convex parts, the effect of suppressing shedding of fuzz and the texture felt by the skin at the convex parts are improved.
When the nonwoven fabric of the present invention is used as a component on the skin side of the absorbent body in an absorbent article, the above-mentioned effects are maintained even if friction due to contact with the skin is continued, and the comfortable fit is likely to be sustained.
In the past, when a die was used to form unevenness in the manufacturing process of nonwoven fabric, the passage of hot air was poor, making it easier for fuzz to fall off. For example, in the case of a nonwoven fabric manufactured by forming unevenness on a fiber web and then forming fusion points by hot air treatment, if the unevenness of the die was enlarged to increase the apparent thickness while suppressing the basis weight for texture, fuzz would fall off more easily. In particular, in the case of air-through nonwoven fabric, compared to spunbonded nonwoven fabrics that use long fibers that are less likely to fall off, this is all the more true because short fibers are used for heat fusion. In the past, there were measures to prevent fuzz from falling off, such as increasing the temperature of the hot air treatment or increasing the number of times spunlacing was performed, but these could lead to hardening of the nonwoven fabric and a decrease in texture.
In contrast, the nonwoven fabric of the present invention has an uneven shape defined by the apparent thickness and contact area, and has the attached polymer on the skin-facing side, thereby achieving suppression of shedding while maintaining a soft feel.

The nonwoven fabric of the present invention preferably has an uneven shape and has a wall surface in the thickness direction connecting the front and back surfaces of the nonwoven fabric. For example, the uneven nonwoven fabric 10 shown in FIG. 1(A) has a slightly inclined wall surface 14 connecting the top 12A of the pyramidal protrusion 12 on the skin side 1A to the top 13A of the pyramidal protrusion 13 on the non-skin side 1B. Also, the uneven nonwoven fabric 20 shown in FIG. 1(B) has a vertical wall surface 24 connecting the flat top 22A of the columnar protrusion 22 on the skin side 1A to the flat top 23A of the columnar protrusion 23 on the non-skin side 1B.

From the viewpoint of further enhancing the above-mentioned effects, the attachment polymer preferably has a glass transition point of 0°C or lower, and more preferably -10°C or lower. From the viewpoint of availability, the attachment polymer preferably has a glass transition point of -120°C or higher, more preferably -100°C or higher, and even more preferably -80°C or higher.

In the nonwoven fabric of the present invention, the mass content of the aforementioned attached polymer is preferably 6% by mass or more, more preferably 7% by mass or more, and even more preferably 8% by mass or more, based on the mass of the nonwoven fabric of the present invention, from the viewpoint of suppressing shedding. The mass content of the aforementioned attached polymer is preferably 20% by mass or less, more preferably 17% by mass or less, and even more preferably 14% by mass or less, based on the mass of the nonwoven fabric of the present invention, from the viewpoint of improving the texture of the nonwoven fabric. This mass content is far greater than the amount of additives such as fiber treatment agents that are usually added.

In addition, in the nonwoven fabric of the present invention, from the viewpoint of suppressing shedding as described above, improving the smoothness and good feel due to the attached polymer at the aforementioned thickness, and providing a soft and flexible feel, the basis weight is preferably 70 g/ ^m2 or less, more preferably 60 g/ ^m2 or less, and even more preferably 50 g/ ^m2 or less.
In addition, the lower limit of the basis weight is not particularly limited, but from the viewpoint of improving the texture of the nonwoven fabric, it is preferably 15 g/ ^m2 or more, more preferably 20 g/ ^m2 or more, and even more preferably 25 g/ ^m2 or more.

The glass transition point of the aforementioned attached polymer and the mass percentage of the attached polymer in the nonwoven fabric can be measured by the following method.

(Method of measuring glass transition point of attached polymer and mass proportion of attached polymer in nonwoven fabric)
(1) Remove the nonwoven fabric from the product and prepare a 0.3 g nonwoven fabric sample as a measurement sample. Measure the mass of the nonwoven fabric sample at this point and call it mass A. Next, place the nonwoven fabric sample in a beaker containing 100 mL of ethyl acetate and stir for 30 minutes, remove the nonwoven fabric sample and dry it. This washes away any components attached to the nonwoven fabric sample, such as skin care agents and hot melt adhesives. Repeat this process to prepare 1.0 g or more of sample.
(2) The nonwoven fabric sample is placed horizontally and the horizontal cross section is cut and cut into pieces of about 0.1 mm in length. 1.0 g of this nonwoven fabric sample is placed in a beaker and hexafluoroisopropanol (hereinafter also referred to as HFIP) is added to separate it into HFIP insoluble and HFIP soluble parts. This dissolves the polyethylene terephthalate (hereinafter also referred to as PET) component of the fiber.
(3) The HFIP insoluble matter obtained in (2) is added to heated xylene at 130°C, thoroughly stirred, and filtered to separate it into heated xylene insoluble matter and heated xylene soluble matter. This dissolves the polypropylene (hereinafter also referred to as PP) and polyethylene (hereinafter also referred to as PE) components of the fibers. The cellulosic fibers remain. The mass of the heated xylene insoluble matter is measured and designated as mass B.
(4) The heated xylene insoluble matter obtained in (3) above is measured by Fourier transform infrared spectroscopy (hereinafter also referred to as FT-IR) to determine the monomer composition, and the glass transition point is calculated from the following Fox formula (S1) (Adhesive Handbook, 2nd Edition, p. 144, October 12, 1995, published by the Japan Adhesive Tape Industry Association). However, if a peak derived from cellulose is observed in FT-IR, that peak is not used in the calculation.
(5) Thermogravimetric analysis (TGA) is performed up to 600° C. for the heated xylene insoluble matter obtained in (3). The mass of the residue is measured and designated as mass C. Mass C is subtracted from mass B obtained in (3) (mass B−mass C) to calculate the mass of the attached polymer (mass D). This mass of the attached polymer (mass D) is divided by the mass of the nonwoven fabric (mass A) to obtain the mass ratio of the attached polymer in the nonwoven fabric sample.

In the formula, Tg represents the glass transition point of the attached polymer, Tg _i represents the glass transition point of a polymer made from monomer i, and W _i represents the mass fraction of monomer i in the attached polymer.

The aforementioned "polymer having a glass transition point of 10° C. or less" has a binding property that does not flow off when it is fixed. At the same time, the attachment polymer has elasticity or flexibility that enhances the smoothness of the nonwoven fabric surface. The attachment polymer is fixed by coating the surface of the fibers constituting the nonwoven fabric of the present invention. The coating may be partial on the fiber surface. The attachment polymer is fixed to the surface of the fibers so as to form a membrane in the space surrounded by the fibers, which is formed by the intersection of the fibers (for example, the membrane 61 of the attachment polymer formed in the space surrounded by the fibers 7 shown in FIG. 2). The surface of the fibers to which the attachment polymer is fixed includes the surface of the fusion point between the fibers. It is preferable that the attachment polymer present on the surface of the fusion point covers the outer surface of the part where the fibers cross and overlap (the outer surface of the fused fibers).
In this way, the attachment polymer reduces the hardness of the fiber surface at the portion where it is fixed to the fiber, giving the fiber a soft feel. The attachment polymer also bonds the fibers together, imparting an adhesive strength to the nonwoven fabric of the present invention that is greater than the fusion point. In particular, as shown in Figure 2, the attachment polymer film 61 extends beyond the fusion point and increases the adhesive strength between the fibers. The attachment polymer and the fusion point can be visually distinguished using a tabletop scanning electron microscope (SEM).

The attachment polymer is a resin component different from the constituent fibers of the nonwoven fabric, and is fixed to the surface of the constituent fibers after the nonwoven fabric is made. It can be fixed to one surface (skin-facing side) of the nonwoven fabric by, for example, spraying, coating, impregnation, etc. As a result, the attachment polymer is uniformly fixed over the entire skin-facing side of the nonwoven fabric of the present invention. In particular, when the skin-facing side of the nonwoven fabric of the present invention has an uneven shape, spraying by spraying or impregnation is preferable from the viewpoint of fixing the attachment polymer along the uneven shape.
When the adhesion polymer is fixed, the coating agent before the application of the adhesion polymer may be applied as a 100% solution, but it is preferable to dilute and apply it from the viewpoint of suitable control of the application amount. Examples of the dilution liquid include water and ethanol. From the viewpoint of workability, the diluted polymer coating liquid is preferably a liquid in which the content concentration of the polymer having a glass transition point of 10° C. or less is 3% by mass or more and 55% by mass or less, and more preferably a liquid in which the content concentration is 5% by mass or more and 10% by mass or less.
The coating agent before application of the adhesion polymer (hereinafter also referred to as the adhesion polymer coating agent) refers to the agent before reactions such as crosslinking occur after application. The adhesion polymer coating agent is mainly solid, but may be liquid. A 100% solution of the adhesion polymer coating agent and a diluted one are referred to as the adhesion polymer coating liquid (a solution before dilution may be referred to as the adhesion polymer solution).

As the attachment polymer, various polymers having the above-mentioned glass transition point can be used.
For example, polymers having a polyethylene component as a constituent component, polymers having a butadiene component, polymers having an isoprene component, and polymers having an acrylic ester component in which ^R2 in the following formula (I) is an alkyl group having 2 or more carbon atoms can be mentioned. Examples include polyethylene polymers, styrene-butadiene rubber (SBR), and (meth)acrylic polymers. Here, the term "(meth)acrylic polymer" includes both acrylic polymers and methacrylic polymers.

In the formula (I), R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group or a hydrogen atom.

For example, the ethylene component contained in the polymer is preferably 40% by mass or more and 80% by mass or less based on the total mass of all components, and the polymer is preferably one or more components selected from the group consisting of the butadiene component, the isoprene component, and the acrylic acid ester component represented by the above formula (I) are preferably 40% by mass or more based on the total mass of all components.
This allows the attached polymer to have no melting point, which increases flexibility and enhances the effect of reducing hardening of the fiber surface, thereby preventing deterioration of the feel of the nonwoven fabric of the present invention.

Further, it is more preferable that the ethylene component contained in the polymer is 60% by mass or more and 80% by mass or less based on the total mass of all components, and it is more preferable that the polymer is one or more components selected from the group consisting of the butadiene component, the isoprene component, and the acrylic acid ester component represented by the above formula (I) is 60% by mass or more based on the total mass of all components.
This makes the glass transition point of the attached polymer equal to or lower than 0° C., and the above-mentioned action of the attached polymer can be effectively exerted regardless of the outside air temperature.

In the nonwoven fabric of the present invention, from the viewpoints of suppressing shedding and achieving a smooth feel and favorable texture, the proportion of the adhesion area of the adhesion polymer to the surface area of the skin-facing side is preferably 20% or more, more preferably 25% or more, and even more preferably 30% or more, whereby the adhesion polymer is more evenly adhered to the skin-facing side, and the above-mentioned effects are further enhanced.
From the viewpoint of improving the feel of the nonwoven fabric, the proportion of the adhesion area of the adhesion polymer to the surface area of the skin-facing side is preferably 60% or less, more preferably 55% or less, and even more preferably 50% or less.

In the nonwoven fabric of the present invention, the adhesion area of the adhesion polymer on the skin side is preferably at least twice, more preferably at least 2.5 times, and even more preferably at least 3 times, the adhesion area of the adhesion polymer on the non-skin side, whereby a larger proportion of the adhesion polymer by mass in the entire nonwoven fabric is distributed on the skin side, thereby further enhancing the above-mentioned effect.
Furthermore, from the viewpoint of improving the feel of the nonwoven fabric, the adhesion area of the attached polymer on the skin-facing side is preferably 5 times or less, more preferably 4.5 times or less, and even more preferably 4 times or less, of the adhesion area of the attached polymer on the non-skin-facing side.

(Method of measuring the adhesion area and adhesion area ratio of the adhesion polymer on the skin-facing side and non-skin-facing side)
(1a) The above-mentioned process (1) in (Method for measuring the glass transition temperature of the deposited polymer) is carried out.
(1b) The nonwoven fabric sample is dyed using an identification reagent (fiber identification reagent Bouken Stain II, manufactured by Bouken Quality Evaluation Organization, a general incorporated foundation) that dyes the attached polymer fixed to the fiber surface a color different from the fiber to distinguish between the two.
(1c) With the nonwoven fabric sample placed on a horizontal surface with the non-skin side facing up, an observation image is taken at 150x magnification of each exposed surface side (the skin side when the non-skin side is placed down, and the non-skin side when the skin side is placed down) using a digital microscope VHX-900 (product name, manufactured by Keyence Corporation; all digital microscopes in this specification refer to this type). The captured image is the observation image. The observation image size is 1600 x 1200 pixels.
(1d) The observed images of the skin-facing side and the non-skin-facing side are each subjected to a ternary value process, and the fiber regions not covered with the attached polymer, the attached polymer regions, and other regions (such as voids between fibers) are identified based on the ternary values, thereby confirming the presence of the attached polymer on both the skin-facing side and the non-skin-facing side. Then, the attached area and the attached area ratio of the attached polymer on each of the skin-facing side and the non-skin-facing side are calculated from the observed images.

The dyeing process (1b) will now be described.
(1b-1) Shake the container of Bouken Stain II well to mix thoroughly.
(1b-2) Place 5 mL of the mixed Bouken Stain II in a beaker of approximately 200 mL size, add tap water, and make the dye solution to a total volume of 100 mL.
(1b-3) The dye solution is heated, and when the temperature is about 90°C before boiling, the nonwoven fabric sample is added and boiled at 95°C for 2 minutes.
(1b-4) The nonwoven fabric sample is taken out, thoroughly washed with water, and then dried.
(1b-5) The color is compared with the identification color and judged. For example, the attached polymer containing acrylic resin or styrene-butadiene rubber is dyed red and the fiber remains white. However, the color of the dyed attached polymer varies depending on the attached polymer component.

A specific example of the calculation process of (1d) above is shown below. In this example, the fiber identification reagent Bouken Stain II is used to dye the attached polymer region containing acrylic resin or styrene-butadiene rubber red, the fiber region remains white, and other regions other than the attached polymer region and the fiber region (such as voids between fibers) are black.
(1d-1) The observed image is subjected to a three-value process (white, red, black). This is performed by image processing on a computer, and becomes a red area in the RGB color model.
(1d-2) Convert from the RGB color model to the HSV color model. In the HSV color model, red is defined as H: 0° to 30° and 270° to 360°, S: 30% to 100%, and V: 40% to 100%. White is defined as H: 0° to 360°, S: 0% to 20%, and V: 40% to 100%. Black is defined as any range other than the above.
(1d-3) In this way, the red area (deposited polymer) and the white area (fiber) are calculated in the HSV color model, and the process of (1d) above is carried out.
Specifically, the number of pixels in the observed image that were determined to be red was taken as the adhesion area (unit: px) of the adhered polymer on each of the skin-facing side and non-skin-facing side.
From the obtained value, the adhesion area ratio of the adhered polymer is calculated based on the following formula (S2).
Adhesion area ratio of the adhering polymer (%) = Adherence area of the adhering polymer (px) ÷ Number of pixels in the entire image (1600px × 1200px) × 100 (S2)
The average values of the three observed images are regarded as the percentage of the attached polymer area on each of the skin-facing side and non-skin-facing side of the nonwoven fabric being measured.

The nonwoven fabric of the present invention has an improved smoothness on the skin side and a good texture due to the presence of the attached polymer as described above. From the viewpoint of smoothness, the mean deviation (MMD) of the coefficient of friction on the skin side is preferably 0.011 or less, and more preferably 0.0105 or less.
In addition, from the viewpoint of suppressing shedding, the mean deviation (MMD) of the coefficient of friction on the skin side is preferably 0.004 or more, more preferably 0.005 or more, and even more preferably 0.006 or more (because a low MMD means that the fibers are easy to move and the fusion is weak).
The mean deviation (MMD) of the coefficient of friction is an index of the surface roughness of the nonwoven fabric, and a smaller value indicates that the friction of the nonwoven fabric surface with the skin is smaller and smoother.

(Method of measuring the average deviation of the friction coefficient)
A commercially available measuring device (KES-FB4 surface tester manufactured by Kato Tech Co., Ltd.) is used to measure the surface friction coefficient (μ) by contacting the measuring terminal of the measuring device with the skin side of the nonwoven fabric. The measurement conditions are speed: 1 mm/sec, initial tension: 150 g, roughness pressure: 50 gf, and terminal travel distance L: 0 mm to 30 mm.
From the obtained friction coefficient (μ), the mean deviation of the friction coefficient (MMD) is calculated based on the following formula (S3): The skin-facing side of the nonwoven fabric is measured, and this is taken as the mean deviation of the friction coefficient of the skin-facing side of the nonwoven fabric.

Ｌ：端子の移動距離、μ：摩擦係数、μ(－)：平均摩擦係数

L: Distance traveled by the terminal, μ: Coefficient of friction, μ(-): Average coefficient of friction

The nonwoven fabric of the present invention, by having the attached polymer as described above, effectively prevents shedding even when subjected to friction. From this perspective, in the fuzz test described below on the skin side, the number of pills generated is preferably 3 or less, more preferably 2 or less, and even more preferably 1 or less.

(Fluffing test)
A disk (70 mm in diameter, 350 g) covered with urethane foam (Malt Filter MF-30, manufactured by Inoac Corporation, thickness 5 mm) was attached to a rotating shaft at a position 20 mm away from the center of the disk.
The same urethane foam as above is laid on the underside of the nonwoven fabric to be measured. Next, the nonwoven fabric is fixed on a table with the skin side facing up. The disk is placed on the nonwoven fabric. At this time, the load applied to the nonwoven fabric is only the weight of the disk. In this state, the rotating shaft is rotated to rotate the disk on the nonwoven fabric. The rotation is performed for 15 sets, with one set being three rotations clockwise and three rotations counterclockwise. The rotation speed at this time is about 3 seconds per rotation. After the 15 sets of rotation, the pills attached to the surface of the urethane foam covering the disk are collected and counted.
The fur ball is approximately spherical and has a diameter of 500 μm, which is larger than a perfect sphere.

When the nonwoven fabric of the present invention 1 has an uneven shape, various uneven shapes can be used. In addition, various materials that are usually used as materials that come into contact with the skin can be used.
For example, there are various types of uneven shapes of nonwoven fabrics, such as those with solid convexities, those with hollow convexities, those with a single fiber layer structure, those with a double fiber layer structure, those with convexities arranged in a scattered manner in a planar direction, those with convexities and concaves arranged in a ridge-like pattern, etc. In addition, the uneven shape is not limited to being on one side, and may be on both sides.
Among these, preferred is a nonwoven fabric having a single layer structure in which the convex portions of the concave-convex shape are hollow and the concave-convex shape is present on both sides of the nonwoven fabric, for example, the following nonwoven fabric 80 (specific example 1) and nonwoven fabric 90 (specific example 2).
These are explained below.

The nonwoven fabric 80 (Specific Example 1) has a single layer structure containing thermoplastic fibers, and has the uneven shape shown below.
That is, it has outer surface fiber layers 81, 82 on the first surface (skin side) 1A side and the second surface (non-skin side) 1B side, and a plurality of connecting portions 83 disposed between the outer surface fiber layer 1 on the first surface 1A side and the outer surface fiber layer 2 on the second surface 1B side. The outer surface fiber layer 81 on the first surface 1A side and the outer surface fiber layer 82 on the second surface 1B side and the connecting portions 83 are partially fused to each other.
In this nonwoven fabric 80, either the first side 1A or the second side 1B is the skin side (surface, use side), and at least on the skin side, the attached polymer is present on the fiber surface, and the attached polymer is attached so as to cover the fiber entanglement points.
The outer fiber layers 81, 82 and the connecting portion 83 form an uneven shape in the thickness direction of the nonwoven fabric 80, which includes hollow convex portions, concave portions, and wall surfaces connecting the convex portions and the concave portions. The uneven shape is formed on both the first surface 1A side and the second surface 1B side. Specifically, on the first surface 1A side, the convex portions 81 formed by the outer fiber layer 81 and the concave portions 88 between the outer fiber layers 81 have an uneven shape. On the second surface 1B side, the convex portions 82 formed by the outer fiber layer 82 and the concave portions 89 between the outer fiber layers 82 have an uneven shape. Both the convex portions 81 formed by the outer fiber layer 81 and the convex portions 82 formed by the outer fiber layer 82 are hollow. The connecting portion 83 forms a wall surface 83 connecting the convex portions 81 and the concave portions 88 (the convex portions 82 and the concave portions 89).
The nonwoven fabric 80 may employ various configurations described in paragraphs [0010] to [0048] of JP 2019-44319 A. For example, the uneven shape of the nonwoven fabric 80 may be a shape in which the convex portions 81 formed by the outer surface fiber layer 81 and the concave portions 88 between them are arranged in a ridge-like shape on the first surface 1A side. Similarly, the convex portions 82 formed by the outer surface fiber layer 82 and the concave portions 89 between them may be arranged in a ridge-like shape on the second surface 1B side. In addition, the outer surface fiber layers 81 and 82 may have fibers oriented in the planar direction. The wall surface 83 formed by the connecting portion 83 may have fibers oriented vertically (oriented in the thickness direction of the nonwoven fabric). The outer surface fiber layer 1 that becomes the convex portion on the first surface 1A side may have two types (a first outer surface fiber layer 81A and a second outer surface fiber layer 81B) having lengths extending along different directions that intersect in a plan view of the nonwoven fabric. The multiple connecting parts 83 may be arranged along different directions that intersect in a plan view of the nonwoven fabric, and may have two types (first connecting parts 83A and second connecting parts 83B) with different wall surface orientations of the connecting parts 83. In this case, the first connecting parts 83A and the second connecting parts 83B may have different wall surface orientations and the fibers may be oriented vertically (oriented in the thickness direction of the nonwoven fabric).
The nonwoven fabric 80 typically has the shape shown in FIG.
Such an uneven shape of nonwoven fabric 80 can be produced by the method described in paragraphs [0049] to [0057] of JP 2019-44319 A.

The nonwoven fabric 90 (Specific Example 2) has a single layer structure containing thermoplastic fibers, and has the uneven shape shown below.
That is, on the first surface (skin surface) 1A side, a plurality of vertical ridges 911 protruding toward the first surface 1A side in the thickness direction of the nonwoven fabric are arranged extending in one direction on the first surface 1A side in a plan view. The vertical ridges 911 are arranged side by side at intervals in another direction on the first surface 1A side in a plan view different from the one direction on the first surface 1A side. In addition, horizontal ridges 921 extending in the other direction on the first surface 1A side are arranged connecting the vertical ridges 911. The vertical ridges 911 and the horizontal ridges 921 each form a hollow convex portion. The nonwoven fabric 90 has an uneven shape in its thickness direction, which includes convex portions, concave portions, and wall surfaces 911W connecting the convex portions and the concave portions, by the vertical ridges 911 and the horizontal ridges 921 and the concave portions 922 between them. On the first surface 1A side, the convex portions formed by the vertical ridge portions 911 and the horizontal ridge portions 921 have lengths extending along different directions that intersect in a plan view of the nonwoven fabric 90. In this case, the uneven shape on the first surface side of the nonwoven fabric 90 may be a shape in which the convex portions formed by the vertical ridge portions 911 and the horizontal ridge portions 921 and the concave portions therebetween are arranged in a ridge-groove shape.
In addition, on the second surface (opposite surface) 1B side, a plurality of hollow convex streaks 931 are arranged, which extend in one direction on the second surface 1B side in plan view and are arranged in another direction on the second surface 1B side different from the one direction on the second surface 1B side. In addition, a concave streaks 936 sandwiched between the plurality of convex streaks 931 extends in one direction on the second surface 1B side. The uneven shape on the second surface 1B side of the nonwoven fabric 90 has a shape in which the convex streaks 931 and the concave streaks 936 are arranged in a ridge-like shape. The convex streaks 931 are formed by a plurality of convex portions 934 connected in a ridge-like shape, and narrow and wide portions are alternately connected in a plan view. Between the convex portions 934 connected in a ridge-like shape, there is a slightly low depression 935. The nonwoven fabric 90 has an uneven shape in its thickness direction, which includes protrusions, recesses, and wall surfaces 931W connecting the protrusions and recesses, formed by the protrusions 931 and the recesses 936.
In this nonwoven fabric 90, either the first side 1A or the second side 1B is the skin side (surface, use side), and at least on the skin side, the attached polymer is present on the fiber surface, and the attached polymer is attached so as to cover the fiber entanglement points.
The nonwoven fabric 90 may employ various configurations described in paragraphs [0012] to [0058] of JP 2019-44320 A. For example, the orientation direction of the fibers constituting the vertical ridge portion 911 and the fibers constituting the horizontal ridge portion 921 may be different. The height of the vertical ridge portion 911 and the height of the horizontal ridge portion 921 may be different, and the horizontal ridge portion 921 may be curved in the thickness direction of the nonwoven fabric 90 or may have an equal height. In addition, each of the two lines constituting the widthwise outline of the convex strip portion 931 when viewed in plan from the second surface 1B side may be a curve having multiple arcs. Fuzz may be arranged on the side of the convex strip portion 931.
The nonwoven fabric 90 typically has the configuration shown in FIGS.
Such an uneven shape of nonwoven fabric 90 can be produced by the method described in paragraphs [0059] to [0065] of JP2019-44320A.

The method for producing the nonwoven fabric of the present invention preferably includes a step of forming the uneven shape as described above into a raw nonwoven fabric, spraying the adhesion polymer coating solution with a spray or the like, and drying the raw nonwoven fabric. This can avoid adhesion (sticking) between the nonwoven fabric and the mold for forming unevenness used when producing a nonwoven fabric from a fiber web. In addition, if the uneven shape is formed before spraying the adhesion polymer, the movement of the fibers is kept high in the absence of the adhesion polymer, so that the shapeability can be improved.
Moreover, the spraying method is preferable because it is possible to suitably control the amount of the adhesive polymer applied to the nonwoven fabric.
In the above-mentioned manufacturing method, the adhesive polymer coating solution is preferably sprayed from the skin-facing side of the raw nonwoven fabric, which is preferable because this ensures that the adhesive polymer adheres more reliably to the skin-facing side of the nonwoven fabric of the present invention.

For example, the method for producing a nonwoven fabric of the present invention is preferably carried out through the steps shown in FIG.
In Fig. 10 (A) and (B), a fiber web 110 containing thermoplastic fibers is placed on a support male member 120, and a support female member 130 is pressed into the support male member 120 from above the fiber web 110. At this time, the protrusion 121 of the support male member 120 is inserted into the support recess 132 of the support female member 130. Also, the protrusion 131 of the support female member 130 is inserted into the support recess 122 of the support male member 120. This causes the fibers to be oriented in the thickness direction and the planar direction. Next, as shown in Fig. 10 (C), the support female member 130 is removed, and hot air W is blown from above the shaped fiber web to fuse the fibers together. This forms a raw material nonwoven fabric 140.
Thereafter, as shown in Figures 10(D) and (E), the raw nonwoven fabric 140 is removed from the support male material 120, and the adhesive polymer coating solution 66 is sprayed on the raw nonwoven fabric by a spray or the like to fix the adhesive polymer 6, thereby obtaining the nonwoven fabric of the present invention. At this time, it is preferable that the surface side on which the adhesive polymer coating solution 66 is sprayed on the raw nonwoven fabric is the surface side 1A opposite to the surface side 1B on which the hot air is blown in Figure 10(D). This allows the surface 1A, which is relatively superior in terms of softness to the touch as the fusion of the fibers by the hot air is relatively suppressed, to be the surface on which the adhesive polymer is fixed, and the surface side 1A can be used as the skin side during use.

The drying temperature is preferably 60°C or higher, more preferably 100°C or higher, and even more preferably 110°C or higher. This is preferable because it facilitates the crosslinking reaction of the adhesion polymer coating agent in the sprayed adhesion polymer coating solution, and it facilitates the improvement of the strength of the fiber surface and the adhesive strength at the fusion points. From the viewpoint of improving the texture of the nonwoven fabric, the drying temperature is preferably 130°C or lower, more preferably 125°C or lower, and even more preferably 120°C or lower. Furthermore, from the viewpoint of improving the crosslinking reaction of the polymer, the drying time is preferably 1 minute or longer, more preferably 3 minutes or longer, and even more preferably 5 minutes or longer.

The spray mass of the adhesion polymer coating agent is preferably 6 g/ ^m2 or more, more preferably 8 g/ ^m2 or more, per unit area of the raw nonwoven fabric from the viewpoint of suppressing fluff shedding. Also, the spray mass of the adhesion polymer coating agent is preferably 25 g/ ^m2 or less, more preferably 20 g/ ^m2 or less, per unit area of the raw nonwoven fabric from the viewpoint of improving production efficiency and preventing contamination of the production line.
In addition, within the above range, the spray mass of the adhesion polymer coating agent can be appropriately set depending on the application of the nonwoven fabric. When the nonwoven fabric of the present invention is used for sanitary products (absorbent articles, wiping sheets, masks, etc.), the spray mass of the adhesion polymer coating agent is preferably 5 g/ ^m2 or more and 20 g/ ^m2 or less, more preferably 7 g/ ^m2 or more and 15 g/ ^m2 or less, per unit area of the raw material nonwoven fabric, from the viewpoint of improving the texture of the nonwoven fabric.

Next, the thermoplastic fibers constituting the nonwoven fabric of the present invention will be described.
The thermoplastic fibers may be any fibers that are commonly used as materials for nonwoven fabrics without any particular limitations. For example, the fibers may be made of a single resin component, or may be composite fibers made of multiple resin components. The composite fibers may have, for example, a core-sheath structure or a side-by-side structure.
When using composite fibers containing a low melting point component and a high melting point component as the thermoplastic fiber (for example, composite fibers having a core-sheath structure in which the sheath is a low melting point component and the core is a high melting point component), the temperature of the hot air blown onto the fiber web in the manufacturing process is preferably equal to or higher than the melting point of the low melting point component and lower than the melting point of the high melting point component. More preferably, the temperature is equal to or higher than the melting point of the low melting point component and lower than the melting point of the high melting point component by 10°C or more, and even more preferably, the temperature is higher than the melting point of the low melting point component by 5°C or more and lower than the melting point of the high melting point component by 20°C or more. In addition, from the viewpoint of elasticity, the more the core of the core-sheath structure composite fibers have, the higher the elasticity. Therefore, it is preferable that the core component is larger in terms of cross-sectional area ratio. Specific examples of composite fibers having a core-sheath structure in which the sheath is a low melting point component and the core is a high melting point component include composite fibers having a core-sheath structure in which the sheath is a polyethylene resin (hereinafter also referred to as PE) and the core is a polyethylene terephthalate resin (hereinafter also referred to as PET).
Furthermore, in composite fibers with a core-sheath structure, when the resin component of the sheath has a lower glass transition point than the resin component of the core (hereinafter referred to as low glass transition point resin) (for example, the resin component of the core is PET and the resin component of the sheath is PE), the thickness recovery of the nonwoven fabric can be further improved by reducing the mass ratio of the low glass transition point resin component.

Such a nonwoven fabric of the present invention can be used for various purposes.
For example, the nonwoven fabric of the present invention can be used in absorbent articles such as diapers, sanitary napkins, panty liners, and urine pads. Absorbent articles typically have a liquid-permeable top sheet, a back sheet, and an absorbent sandwiched between them. The nonwoven fabric of the present invention can be particularly suitably used as a top sheet. Furthermore, the nonwoven fabric can also be used as a sheet in the gather part, an exterior sheet, or a sheet in the wing part of an absorbent article.
The nonwoven fabric of the present invention can also be used as a component of an eye mask or a mask.

The present invention will be explained in more detail below based on examples, but the present invention should not be construed as being limited thereto. In the examples, "parts" and "%" are all based on mass unless otherwise specified. In Table 1 below, "-" means that the item does not have a corresponding value, etc.

Example 1
(1) Preparation of raw material nonwoven fabric First, a fiber web was prepared using thermoplastic fibers of a core-sheath type (polyethylene terephthalate (PET) (core): polyethylene (PE) (sheath) = 5:5 (mass ratio)) with a fineness of 1.8 dtex. The fiber web was subjected to uneven shaping using the same male support material and female support material as in Example 1 described in JP-A-2019-44320 (FIGS. 13(A) to (C) of the same document). At that time, the female support material was pushed in by 1 mm.
Next, the female support was removed, and the shaped fiber web held on the male support was transported at a transport speed of 10 m/min, while a hot air blowing treatment (air-through treatment) was performed twice from above the fiber web. The first blowing treatment was performed under conditions of a temperature of 140° C., a wind speed of 68 m/sec, and a blowing time of 5 seconds. The second blowing treatment was performed under conditions of a temperature of 140° C., a wind speed of 6.0 m/sec, and a blowing time of 5 seconds.
As a result, a raw material nonwoven fabric having a constituent fiber fineness of 1.8 dtex and a basis weight of 40±4 g/ ^m2 and having the uneven shape shown in Figures 4 to 9 was produced. The size of the raw material nonwoven fabric was 100 mm x 100 mm.
(2) Preparation of Adhesion Polymer Coating Solution An adhesion polymer coating solution was prepared by mixing 10% by mass of an adhesion polymer solution with a solid content of about 50% and 90% by mass of deionized water. The adhesion polymer solution used had a solid content (adhesion polymer coating agent) with a glass transition point of -40°C (Boncoat AB-886 (product name) manufactured by DIC Corporation. Ingredients: 50.8% by mass of acrylic resin, 45-55% by mass of water, less than 1% by mass of n-butyl acrylate, less than 1% by mass of isopropyl alcohol, and less than 1% by mass of others). The adhesion polymer solution had a pH of 6.6 and a viscosity of 40 mPa·s.
(3) Spraying of Adhesion Polymer Coating Solution Next, the first surface 1A of the raw nonwoven fabric, on which the vertical ridges 911 and horizontal ridges 921 shown in Fig. 4 are arranged, is set as the skin-facing side (front surface), and the adhesion polymer coating solution is evenly applied to the first surface 1A by spraying. Next, the raw nonwoven fabric is dried at 100°C for 5 minutes in an electric dryer.
This produced nonwoven fabric sample A1 of Example 1 having the apparent thickness and contact area shown in Table 1. The apparent thickness and contact area were measured based on the above-mentioned (Method for measuring the apparent thickness of a nonwoven fabric under a load of 0.05 kPa) and (Method for measuring the contact area).
The applied amount of the solid content of the deposition polymer solution (the mass ratio to the mass of the raw nonwoven fabric) was 8.37% by mass, which was measured based on the change in the mass of the nonwoven fabric before and after the deposition polymer was applied.

Example 2
Nonwoven fabric sample A2 of Example 2 was prepared in the same manner as in Example 1, except that a coating method was used in which the surface side of the raw nonwoven fabric that would be the skin side (the first surface 1A side shown in FIG. 4 ) was impregnated with the adhesion polymer coating solution.
The coating amount of the solid content of the deposition polymer solution (the mass ratio to the mass of the raw material nonwoven fabric) was 12.9 mass %.

(Comparative Example 1)
A nonwoven fabric sample C1 for Comparative Example 1 was prepared in the same manner as in Example 1, except that an attachment polymer solution having a glass transition point of 40°C (DICFINE AJ-1820 (product name) manufactured by DIC Corporation; components: 50-60% by mass of water, 44.5% by mass of acrylic resin, less than 1% ammonia (containing water), less than 1% others) was used, and the surface of the raw nonwoven fabric that would be the skin side (the first surface 1A side shown in FIG. 4 ) was impregnated with the attachment polymer coating solution. The attachment polymer solution had a pH of 6.1 and a viscosity of 588 mPa s.
The coating amount of the solid content of the polymer solution (the mass ratio to the mass of the raw material nonwoven fabric) was 11.5 mass %.

(Comparative Example 2)
The raw material nonwoven fabric produced in Example 1 was used as nonwoven fabric sample C2 of Comparative Example 2. In other words, nonwoven fabric sample C2 had no adherent polymer.

The following measurements and tests were carried out for each of the above examples and comparative examples.
(1) Adhesion area of the attached polymer on the skin-facing side and the non-skin-facing side, and the adhesion area ratio of the attached polymer on the skin-facing side:
The measurement was performed based on the above-mentioned (Method of measuring the adhesion area of the adhered polymer on the skin-facing side and the non-skin-facing side, and the adhesion area ratio on the skin-facing side).
(2) Mean deviation of friction coefficient on skin side (MMD):
The measurement was performed based on the above-mentioned (Method for measuring the average deviation of the friction coefficient).
(3) Lint shedding test:
The measurements were made based on the above-mentioned (lint test).

As shown in Table 1, the nonwoven fabric samples of each Example had a lower mean deviation (MMD) of the friction coefficient and a better texture than nonwoven fabric sample C1 of Comparative Example 1, which used the same raw nonwoven fabric but had an attached polymer with a glass transition point of 40°C. At the same time, the nonwoven fabric samples of each Example had less pilling and reduced shedding compared to nonwoven fabric sample C2 of Comparative Example 2, which had no attached polymer. In other words, the nonwoven fabric samples of each Example, which are specific examples of the present invention, maintained a soft texture while reducing shedding.

10, 20 Nonwoven fabric 1A Skin-facing side 1B Non-skin-facing side 12, 22 Convex portions 12A, 22A on the skin-facing side Apex of convex portions on the skin-facing side 13, 23 Convex portions 13A, 23A on the non-skin-facing side Apex of convex portions on the non-skin-facing side 14, 24 Wall surface 6 Adhesive polymer 61 Film of adhesion polymer 66 Adhesive polymer coating liquid 7 Fiber

Claims (8)

A nonwoven fabric having fusion points between fibers and having a front surface and a back surface,
The apparent thickness is 1.5 mm or more when a load of 0.05 kPa is applied from one side using a horizontal plate, and the ratio of the contact area between the horizontal plate and the nonwoven fabric under a pressure of 3 kPa to the surface area of the front side is 90% or less,
A nonwoven fabric comprising fibers having a polymer attached thereto, the polymer having a glass transition point of 10° C. or lower, at least on the surface side thereof, the polymer being contained in an amount of 5% by mass or more and 40% by mass or less. The nonwoven fabric according to claim 1, wherein the nonwoven fabric is an air-through nonwoven fabric. The nonwoven fabric according to claim 1 or 2, in which the proportion of the surface area of the polymer attached to the surface side is 20% or more. The nonwoven fabric according to any one of claims 1 to 3, wherein the adhesion area of the polymer on the front side is at least twice the adhesion area of the polymer on the back side. The nonwoven fabric according to any one of claims 1 to 4 , which is for use in absorbent articles. An absorbent article comprising the nonwoven fabric according to any one of claims 1 to 5 . A method for producing the nonwoven fabric according to any one of claims 1 to 5 , comprising the steps of spraying a polymer coating liquid containing a polymer having a glass transition point of 10°C or less onto a raw material nonwoven fabric, and drying the raw material nonwoven fabric. The method according to claim 7 , wherein the polymer coating liquid is a liquid containing 3% by mass or more and 55% by mass or less of a polymer having a glass transition point of 10° C. or less.

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