RU2690149C1 - Three-dimensional sheet and absorbing product using it - Google Patents

Abstract

FIELD: manufacturing technology.SUBSTANCE: three-dimensional sheet (10) includes: first fibrous layer (11), including first surface (111) and second surface (112); and second fibrous layer (12), including first surface (121) and second surface (122). Two fibrous layers are layered so that second surface (112) of first fibrous layer faces first surface (121) of second fibrous layer. In three-dimensional sheet (10), the first fibrous layer (11) protrudes in the direction of separation from the second fibrous layer (12), and as a result a plurality of hollow bosses (20) is formed. Each of first fibrous layer (11) and second fibrous layer (12) is made from nonwoven fabric. First fibrous layer (11) includes fibers of multiple types. Fibers of multiple types include, at least, fibers of two types, including the first fiber and the second fiber. Each of the first fiber and the second fiber includes a refractory component and a low-melting component, and they have different ratios of diameters between the refractory component and the low-melting component.EFFECT: three-dimensional sheet manufacturing technology.35 cl, 10 dwg, 5 tbl

Description

Technical field

[0001]

The present invention relates to a three-dimensional sheet. The present invention also relates to an absorbent article using a three-dimensional sheet.

The level of technology

[0002]

The applicant has previously proposed a three-dimensional sheet suitable for use as a top sheet of an absorbent article, such as a disposable diaper, in which: the bonded areas are formed by partially joining the first nonwoven fabric and the second nonwoven fabric by fusion; and the first non-woven fabric protrudes in the direction of separation from the second non-woven fabric in unconnected areas surrounded by connected areas to form a plurality of protuberances having a hollow inner space (see patent document 1). The bulges in this three-dimensional sheet have a hollow structure. Three-dimensional sheets in which the bulges have a three-dimensional structure are also known in the art (see patent document 2).

[0003]

In addition to the technologies described in Patent Documents 1 and 2, the applicant has also previously proposed a nonwoven web made of fusion-joined fibers of at least two types, interconnection by fusing is difficult, where: fibers of the same type are firmly joined by fusing at their intersection points; and such intersections are present throughout the entire nonwoven web (see Patent Document 3). The specified non-woven fabric has a good texture and is also suitable for use, for example, as a concave textile fastener element, which has excellent strength in relation to the peeling force when a convex textile fastener element is attached to it, and causes a slight tampering when the attached convex peels off. the element, and as a result, the convex element can be reattached.

List of references

Patent literature

[0004]

Patent document 1: JP 2004-174234A

Patent Document 2: JP 2006-175689A

Patent document 3: JP H9-279467A

Summary of Invention

[0005]

The three-dimensional sheets described in Patent Documents 1 and 2 create an excellent cushioning feel, due to their structure of bumps and indentations, and thus provide an excellent texture. However, these three-dimensional sheets still need to be improved in terms of the smoothness of the protuberances and the reduction of skin irritation in those cases where three-dimensional sheets are used, for example, as the top sheet of an absorbent article. In addition, there is still room for improvement with respect to the stability of the protuberances and the resistance of the protuberances to collapse under the effect of the load. On the other hand, the non-woven fabric described in Patent Document 3 is intended primarily for use as a concave element of a textile fastener, and it is not provided for the non-woven fabric to have a three-dimensional shape to improve the sense of cushioning.

[0006]

The present invention provides a three-dimensional sheet comprising: a first fibrous layer comprising a first surface and a second surface opposite to it; and a second fibrous layer comprising a first surface and a second surface opposite to it. The first and second fibrous layers are layered in such a way that the second surface of the first fibrous layer faces the first surface of the second fibrous layer. The interconnected regions are formed by partially bonding by fusing the first fibrous layer and the second fibrous layer, and, between the interconnected regions, the first fibrous layer projects in the direction of separation from the second fibrous layer to form a plurality of protuberances. Each of the first fibrous layer and the second fibrous layer is made of nonwoven fabric. The first fibrous layer includes fibers of many types. Multiple fiber types include at least two fiber types, including the first fiber and the second fiber. Each of the first fiber and the second fiber includes a refractory component and a low-melting component. The ratio of diameters, when calculated by the following equation, between the refractory component and the fusible component of the first fiber is different from the ratio of the diameters between the refractory component and the fusible component of the second fiber:

the ratio of the diameters between the refractory component and the low-melting component (A _X ) = the diameter of the low-melting component of the fiber X (D1) / the diameter of the refractory component of the fiber X (D2).

[0007]

The present invention also provides an absorbent article using the above three-dimensional sheet.

Brief Description of the Drawings

[0008]

[FIG. 1] FIG. 1 is a perspective view illustrating a three-dimensional sheet according to an embodiment of the present invention.

[FIG. 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. one.

[FIG. 3] FIG. 3 is a schematic diagram illustrating an example of a cross sectional structure of a first fiber or a second fiber used in the present invention.

[FIG. 4] FIG. 4 is a schematic diagram illustrating the device used appropriately for making the three-dimensional sheet illustrated in FIG. one.

[FIG. 5] FIG. 5 is a schematic diagram illustrating a state in which the sheet is molded to produce bulges and depressions by using the apparatus illustrated in FIG. four.

[FIG. 6] FIG. 6 (a) and 6 (b) are diagrams that sequentially illustrate the process of manufacturing the three-dimensional sheet in FIG. 1 by using the device illustrated in FIG. four.

[FIG. 7] FIG. 7 (a) is a schematic diagram illustrating a method of defining a boundary when there is a clear visual difference between the side of the first surface and the side of the second surface in the first fibrous layer of a three-dimensional sheet having hollow bulges, and FIG. 7 (b) is a schematic diagram illustrating a boundary definition method when there is a clear visual difference between the side of the first surface and the side of the second surface in the first fibrous layer of a three-dimensional sheet having three-dimensional bumps.

[FIG. 8] FIG. 8 (a) is a schematic diagram illustrating a method of defining a boundary when there is no clear visual difference between the side of the first surface and the side of the second surface in the first fibrous layer of a three-dimensional sheet having hollow bulges, and FIG. 8 (b) is a schematic diagram illustrating a boundary definition method when there is no clear visual difference between the side of the first surface and the side of the second surface in the first fibrous layer of a three-dimensional sheet having three-dimensional bumps.

[FIG. 9] FIG. 9 is a scanned electron microscope image of a three-dimensional sheet obtained according to example 7.

[FIG. 10] FIG. 10 is a scanned electron microscope image of a three-dimensional sheet obtained according to comparative example 2.

Description of embodiments

[0009]

The present invention provides an improved sheet of a three-dimensional form, and more specifically, offers a three-dimensional sheet in which the smoothness of the convexities is improved, while maintaining the sense of cushioning created by the three-dimensional form. The present invention also provides a three-dimensional sheet having protuberances with improved stability and increased resistance to wrinkling under load.

[0010]

The present invention will be described below by means of its preferred embodiments with reference to the drawings. FIG. 1 illustrates a perspective view of a three-dimensional sheet according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. The three-dimensional sheet 10 illustrated in these drawings has an XY plane including one direction X and a second direction Y perpendicular thereto. The three-dimensional sheet 10 includes a first fibrous layer 11 and a second fibrous layer 12, which are layered on each other. The first fibrous layer 11 and the second fibrous layer 12 are in direct contact with each other, and there is no additional layer between the fibrous layers 11, 12. The first fibrous layer 11 includes a first surface 111 and an opposite second surface 112. The second fibrous layer 12 includes a first surface 121 and an opposite second surface 122. The first fibrous layer 11 and the second fibrous layer 12 are layered in such a way that the second surface 112 of the first fibrous layer facing the first surface of the second fibrous layer 121. The first surface 111 of the first fibrous layer constitutes one surface of the three-dimensional sheet 10. The second surface 122 of the second fibrous layer with puts another surface of the three-dimensional sheet 10. Depending on the specific application of the three-dimensional sheet 10, one or more additional layers may be layered on the outer surface of the first surface 111 of the first fibrous layer. Similarly, one or more additional layers may be layered on the outer surface of the second surface 122 of the second fibrous layer.

[0011]

The first fibrous layer 11 and the second fibrous layer 12 are partially joined by fusion bonding, and as a result a plurality of interconnected regions 13 are formed. Between the interconnected regions 13, the first fibrous layer 11 projects in the direction of separation from the second fibrous layer 12 to form a plurality of protuberances 20. Recess 21 is formed between adjacent protuberances 20. The lower part of each recess 21 includes a connected region 13. Thus, the convex-concave structure, consisting of protuberances 20 and recesses 21, is formed on the side of the first surface 111 of the first fibrous layer, which constitutes one surface of the three-dimensional sheet 10. On the other hand, the side of the second surface 122 of the second fibrous layer, which constitutes the other surface of the three-dimensional sheet 10, is in a planar state.

[0012]

Each bulge 20 according to the present embodiment has a hollow structure. More specifically, the hollow space defined by the second surface 112 of the first fibrous layer 11 and the first surface 121 of the second fibrous layer 12 is formed inside each convexity 20. On the other hand, in the recess 21, the first fibrous layer 11 and the second fibrous layer 12 are in close contact with each other, and there is practically no space between the layers. It should be noted that the bulge 20 in the three-dimensional sheet 10 according to the present embodiment is not limited to a hollow structure, and it may have a solid structure in which the bulge 20 is filled with fiber. The fact that the bulge 20 has a hollow structure or a solid structure depends, for example, on the following factors: an increase in the surface density of the nonwoven web on the side of the first fibrous layer 11 or a nonwoven web on the side of the second fibrous layer 12 with the formation of a three-dimensional sheet 10 of sufficient thickness and subsequent processing the resulting sheet; the fabrication of small bumps and depressions on the toothed portion of the first roller 31, which is present in the manufacturing device described later, illustrated in FIG. 4. In order to maintain the stability of the convexity 20 and the resistance to the collapse of the convexity 20 when exposed to a load, it is an advantage that the convexity 20 has a hollow structure.

[0013]

In the XY plane, the bulges 20 are staggered. The recesses 21 are also staggered. The shape and size of each of the bumps 20 are almost the same. The same applies to the recesses 21. In the top view from the side of the first fibrous layer 11 of the three-dimensional sheet 10, the convexity 20 is practically circular. Each bulge 20 has a vertex 201 practically in the central part of the bulge 20, which is practically circular in the top view.

[0014]

As illustrated in FIG. 2, when considering the cross-section in the thickness direction Z, passing the corresponding vertices 201 of the protuberances 20, both the first surface 111 and the second surface 112 of the first fibrous layer 11, which constitute each bulge 20, form a convex curve protruding from the side of the second fibrous layer 12 to the side of the first fiber layer 11. The shapes of the convex curve are the same in any arbitrary cross section in the thickness direction Z, passing through the corresponding vertex 201. Accordingly, each bulge l 20 has the shape of a practically hemispherical shell.

[0015]

In the three-dimensional sheet 10 according to the present embodiment, it is advantageous to control the state of the connection between the constituent fibers contained in the three-dimensional sheet 10. The authors of the present invention found that by controlling the state of the connection between the fibers, the three-dimensional sheet 10 can create an improved cushioning feel, convexities 20, as well as to have an increased deformability of convexities 20 in the direction in the XY plane. Improvements were also found with respect to the stability of the cambers 20 and the resistance of the cambers 20 to collapse under load. Due to these factors, the protuberances 20 have an improved adaptability to the movement of an object in contact with the protuberances 20, and, thus, the friction coefficient is reduced. Reducing the coefficient of friction is mainly in order to reduce skin irritation when the three-dimensional sheet 10 is used, for example, as the top sheet of an absorbent article. In an additional study from this point of view, the authors of the present invention also found that it is advantageous to produce a three-dimensional sheet 10 in such a way that P1 is less than P2 when P1 (number of points / mm3) is the average value of the number S1 connected by fusing the points on the fiber with respect to the density of the fiber on the side of the first surface 111 and the number S2 of fusion-connected points on the fiber with respect to the density of the fiber on the side of the second surface of the first fibrous layer 112, and P2 (number of points / mm3 ) is the number of fusion-connected points on the fiber with respect to the density of the fiber on the side of the first surface 121 of the second fibrous layer.

[0016]

In particular, P1 is preferably 55% or more, preferably 65% or more with respect to P2, and is preferably 95% or less, more preferably 85% or less with respect to P2. More specifically, P1 is preferably from 55 to 95%, more preferably from 65 to 85% with respect to P2.

[0017]

The value of P1 itself is preferably 150 points / mm ³ or more, more preferably 175 points / mm ³ or more, and preferably 240 points / mm ³ or less, more preferably 215 points / mm ³ or less. More specifically, P1 is preferably from 150 to 240 points / mm ³ , more preferably from 175 to 215 points / mm ³ . The value of P2 itself, provided that P2 is larger than P1, is preferably 220 points / mm ³ or more, preferably 240 points / mm ³ or more, and preferably 300 points / mm ³ or less, preferably 280 points / mm ³ or less. More specifically, P2 is preferably from 220 to 300 points / mm ³ , more preferably from 240 to 280 points / mm ³ .

[0018]

P1 and P2 are determined by the number of fusion-connected points on the fiber with respect to the fiber density. Traditionally, in three-dimensional sheets of these types, such as the three-dimensional sheet described in Patent Document 1, the number of fusion-connected points on a fiber increases in proportion to the increase in fiber density. On the other hand, in the three-dimensional sheet according to the present embodiment, the number of fusion-connected points on the fiber is less than in traditional three-dimensional sheets when compared for the same fiber density. In particular, the number of fusion-connected points on the fiber on the second surface 112 of the first fibrous layer is lower compared to traditional three-dimensional sheets. In the three-dimensional sheet according to the present embodiment, P1 is less than P2, and this means that the number of fusion-connected points in the first fibrous layer 11 is less than the number of fusion-connected points in the second fibrous layer 12. A smaller number of fusion-connected points means that there are fewer connected points between the fibers. When there are fewer connected points between the fibers, the freedom of movement of the fibers increases, and thus the fibers easily move within the XY plane in the three-dimensional sheet 10. In other words, compared to the traditional three-dimensional sheets, in the three-dimensional sheet 10 according to the present embodiment, in which P1 is less than P2, bumps 20 can easily be deformed in a direction within the XY plane, and as a result, the adaptability to the movement of an object in contact with ypuklostyami 20. As a result of this largely manifested lowering effect of friction coefficient. Thus, in the three-dimensional sheet 10 according to the present embodiment, the desired properties are manifested by controlling the number of fusion-connected points on the fiber. Specific methods for controlling the number of fusion-connected points on a fiber will be described in detail below.

[0019]

The fiber density, serving as the basis for calculating P1 and P2, is the mass of the nonwoven web relative to unit volume. In the present invention, μg / mm ^{3 is} used as a unit of fiber density. The fiber density on the side of the first surface 111 of the first fibrous layer means the density of the fiber layer located on the side of the top 201 in cases where the first fibrous layer 11 has a two-layer structure, and in those cases where the first fibrous layer 11 has a single-layer structure, it means the density fiber part located on the side of the top 201, when the thickness of the first fibrous layer 11 is divided in half. The fiber density on the side of the second surface 112 of the first fibrous layer means the density of the fiber layer located on the side of the second fibrous layer 12, in cases where the first fibrous layer 11 has a two-layer structure, and in cases where the first fibrous layer 11 has a single-layer structure, it means the fiber density of the part located on the side of the second fiber layer 12 when the thickness of the first fiber layer 11 is divided in half. In cases where the second fibrous layer 12 has a single-layer structure, the fiber density on the side of the first surface 121 of the second fibrous layer 121 means the fiber density of the part located on the side of the first fibrous layer 11 when the thickness of the second fibrous layer 12 is divided in half, and in those cases where the second fibrous layer 12 has a two-layer structure, it means the density of the fiber layer located on the side of the first fibrous layer 11.

[0020]

The boundary between the nonwoven web layers (for example, the boundary between the first fibrous layer 11 and the second fibrous layer 12 or the boundary between the first surface 111 of the first fibrous layer and the second surface 112 of the first fibrous layer) is determined by visual observation of the cross section of the nonwoven fabric with a microscope or scanning electronic microscope (SEM), in cases where the fibrous layers can clearly differ from each other in terms of the amount of fiber, fiber diameter, the ratio between the heart guilt and shell, appearance (whiteness), etc. For example, in cases where the measured three-dimensional sheet 10 has a clear visual difference (for example, in those cases where the three-dimensional sheet 10 includes fibers that contain titanium oxide, and as a result, have a white appearance, and fibers that do not contain oxide titanium or contain little titanium oxide and as a result do not have a white appearance), the interface between the visually different fibrous layers is defined as the border, and the layers differ from each other at the border. In addition, in cases where the three-dimensional sheet 10 includes fibrous layers having a clear visual difference (for example, in those cases where the three-dimensional sheet 10 includes fibers with different diameters or shapes of fibers), the interface between the fibrous layers with different diameters or shapes The fibers are observed using SEM, and the interfacial surface is defined as the boundary on which the layers differ from each other (see Fig. 7 (a) and 7 (b)). In cases where there is no clear visual difference, the cross section of the nonwoven fabric is observed with a microscope (VHX-1000 from Keyence Corporation) to measure the thickness of the nonwoven fabric. When the thickness measured in this way is divided in half, one half is considered as the first layer, and the other half is considered as the second layer. In such cases, for the border between the first surface 111 of the first fibrous layer and the second surface 112 of the first fibrous layer, the thickness of the first fibrous layer 11 is divided in half, as illustrated in FIG. 8 (a), when the bulge 20 of the three-dimensional sheet 10 is hollow, and the thickness between the top 201 and the bottom of the recess 21 is divided in half, as illustrated in FIG. 8 (b), when the protuberances 20 are continuous.

[0021]

A sample for measuring fiber density, the number of fusion-connected points on the fiber, and other parameters are made according to the following procedure. Under conditions of a temperature of 22 ° C and a relative humidity of 65%, a sample having 1 mm in the direction of movement (machine direction) of a three-dimensional sheet of 10 and 1 mm in the perpendicular direction (transverse direction) of a three-dimensional sheet 10 is cut out with a sharp razor from each of the first surfaces 111 of the first fibrous layer, the second surface 112 of the first fibrous layer and the first surface 121 of the second fibrous layer of the measured three-dimensional sheet 10. Samples are cut from two areas on the three-dimensional sheet 10 and are measured. The above procedure is carried out for five three-dimensional sheets 10. The measurement results for all ten areas are averaged to obtain the fiber density, the number of fusion-connected points on the fiber, and other parameters.

[0022]

The fiber density is measured according to the following method. First, the three-dimensional sheet 10 is cut to open its cross-section, and the thickness of the first surface of the first fibrous layer is measured with a microscope (VHX-1000 from Keyence Corporation). In a similar way, measure the thickness of the second surface of the first fibrous layer and the thickness of the second fibrous layer 12. The surface density of each layer is determined and the fiber density is calculated by dividing the surface density by thickness (surface density / thickness). In cases where the layers can be clearly distinguished, the surface density of the first surface of the first fibrous layer and the second surface of the first fibrous layer is determined by: carefully separating the first surface of the first fibrous layer and the second surface of the first fibrous layer at the interface between layers using cold spraying and t d., or cutting along the boundary with a cutter; measuring the mass of the first surface of the first fibrous layer and the mass of the second surface of the first fibrous layer; then measuring the area of the first surface of the first fibrous layer and the second surface of the first fibrous layer after separation; and calculating the result of dividing the mass by the area. In cases where the interlayer boundary does not have a clear visual difference, the mass of the nonwoven web is measured without separation into layers; measure the area; calculate the surface density of the entire non-woven fabric as a result of dividing the mass by the area; and the surface density of the entire non-woven fabric is divided into two, obtaining the surface density of each layer.

[0023]

The number of fusion-connected points on a fiber means the number of fusion-connected points per fiber and is defined in units of “number of points / fiber”. The number of fusion-connected points on the fiber is measured according to the following method. First, the cut sample is placed and the scanning electron microscope (SEM) is mounted on a sample holder made of aluminum, with carbon tape on the sample holder. Then, for example, as illustrated in FIG. 9 and 10, which will be described later, using SEM, an image is obtained with magnification of about 140 to 150. The SEM image is the total number of parts where the fibers are joined by fusing to each other at the corresponding intersection point (circled parts in Fig. 9 and 10). In addition, in the same SEM image, the displayed fiber length is measured for all the fibers illustrated in the image. The above procedures are carried out for five SEM images. In addition, an SEM image with magnification of about 35 is obtained, 50 fibers are selected from one end to the other, and the average length of these fibers is measured and considered as the fiber length for these fibers. The total number of fusion-connected points in the SEM image with a magnification of 140 is divided by the total fiber length in the SEM image with a magnification of 140, the quotient is multiplied by the fiber length for the fibers in the SEM image with a magnification of 35, and as a result, the number of fusion-connected points per fiber is calculated .

[0024]

In the present invention, the mass per fiber means the mass of a single fiber and is determined by the unit “μg / fiber”. The weight per fiber is measured according to the following method. First, at a temperature of 22 ° C and a relative humidity of 65%, a sample of 1 mm in the X direction and 1 mm in the Y direction is cut out with a sharp razor from each of the first surface 111 of the first fibrous layer, the second surface 112 of the first fibrous layer and the first surface 121 the second fibrous layer of the measured three-dimensional sheet 10, and in each sample, the length from one end surface to the other end surface of the fiber is measured using a microscope (VHX-1000 from Keyence Corporation). Alternatively, the fiber length is measured by: placing and fixing each nonwoven fabric on an aluminum sample holder for a scanning electron microscope (SEM), with a carbon tape on the sample holder; and measuring the length from one end surface to the other end surface of the fiber using a scanning electron microscope. In addition, the cross-sectional shape of the fiber is observed using an electron microscope and other means to measure the cross-sectional area of the fiber (the cross-sectional area of each resin component in cases where the fiber is formed from a variety of resins), and the type of resin is determined using differential thermal analysis (DSC) to calculate the specific gravity. Based on this, the linear density of the fiber is calculated. The linear density and fiber length, found according to the above, determine the mass per fiber in the three-dimensional sheet 10.

[0025]

The aforementioned measurement of the number of fusion-connected points on the fiber is made for each section on the side of the first surface 111 of the first fibrous layer, the side of the second surface 112 of the first fibrous layer and the side of the first surface 121 of the second fibrous layer 121. The number of fusion-connected points on the fiber in relation to the fiber density ( number of dots / mm ³⁾ is calculated by performing division of the number F first melting point connected to the fiber (number of dots / fiber) by mass based on the fiber (g / fiber), and tightening m multiply the quotient by a method according to the above measured fiber density ρ (g / mm ^3). In the first fibrous layer 11, the aforementioned P1 value is calculated as the arithmetic average of S1 and S2, (S1 + S2) / 2, where S1 is the number of fusion-connected points on the fiber with respect to the fiber density on the first surface 111 of the first fibrous layer, and S2 is the number of fusion-connected points on the fiber with respect to the density of the fiber on the side of the second surface 112 of the first fibrous layer.

[0026]

In order to satisfy the above-mentioned ratio between P1 and P2, it is advantageous to use specific fibers as fibers constituting the first fibrous layer 11 and the second fibrous layer 12. In particular, it is preferable that the first fibrous layer 11 has a multilayer structure including an upper layer on the side the first surface and the bottom layer on the side of the second surface; and that one or both of the upper layer and the lower layer include fibers of many types. Preferably, multiple types of fibers include at least two types of fibers, including the first fiber and the second fiber. In addition, preferably, each of the first fiber and the second fiber includes a refractory component and a low melting component having a lower melting point than the refractory component. In this case, the refractory component of the first fiber and the refractory component of the second fiber may be of the same type, or they may be of different types. Similarly, the low melting component of the first fiber and the low melting component of the second fiber may be of the same type, or they may be of different types. The reason why it is preferable to use, as each of the first fiber and the second fiber, a fiber comprising a refractory component and a low melting component having a lower melting point than the refractory component, is that when using a fiber comprising a refractory component, it decreases the degree of fusion bonding between the fibers compared with the use of a fiber comprising a low-melting component. The reason for this will be described in detail later. The first fiber and the second fiber are different, having different diameter ratios. In this document, the “diameter ratio” means the ratio between the diameter of the refractory component and the diameter of the low-melting component (μm) in each of the first fiber and the second fiber. If we consider the diameter of the refractory component and the diameter of the low-melting component, for example, D1 and D2, as illustrated in FIG. 3, represent the diameter of the low-melting component C1 and the diameter of the refractory component C2, respectively, in cases where the first and second fibers are two-component fibers containing the core and sheath, in which the shell resin is made of the low melting component and the core resin is made of the refractory component. In addition, the ratio of the diameters A _X between the refractory component C2 and the low-melting component C1 in fiber X is calculated from the equation below. In this document, the term “fusionable fiber of the same type” means fibers made from one or more of the same resins and having the same structure. For example, in cases where there are two bicomponent fibers containing the core and sheath, each of which consists of a refractory component and a fusible component, the two fibers are fusion-bonded fibers of the same type if the two fibers contain the same resin as the refractory component and the other the same resin as a low-melting component, and also have the same ratio of core and shell diameters. On the other hand, when the diameter ratio is different, the two fibers are considered to be fusion-bonded fibers of different types, even if the two fibers contain the same resin as the refractory component, and the other resin as the fusible component. The expression “include fibers of many types” means that they contain fibers of various types connected by fusion.

The ratio of fiber diameters X (A _X ) = diameter of low-melting component of fiber X (D1) (μm) / diameter of refractory component of fiber X (D2) (μm)

[0027]

In the present invention, as described above, the ratio A _{1 of the} diameters of the first fiber is different from the ratio A _{2 of the} diameters of the second fiber. The value of A ₂ / A ₁ , which is the ratio of A ₂ and A ₁ , is preferably less than 1, more preferably 0.99 or less, more preferably 0.91 or less. In addition, the value of A ₂ / A ₁ is preferably 0.5 or more, preferably 0.6 or more, more preferably 0.7 or more. By setting the ratio between A ₁ and A ₂ in this way, the above-mentioned numbers P1 and P2 of the fusion-connected points on the fiber can be easily adjusted. For example, the value of A ₂ / A ₁ is preferably 0.5 or more and less than 1, more preferably from 0.6 to 0.99, more preferably from 0.7 to 0.91.

[0028]

The ratio between the ratio A _{1 of the} diameters of the first fiber and the ratio A _{2 of the} diameters of the second fiber is the same as described above. The value A _{1 of the} ratio of the diameters of the first fiber itself is preferably 1.1 or more, preferably 1.2 or more, more preferably 1.3 or more, and preferably 2.0 or less, preferably 1.9 or less, more preferably 1, 8 or less. More specifically, the value A _{1 of the} ratio of the diameters of the first fiber itself is preferably from 1.1 to 2.0, more preferably from 1.2 to 1.9, more preferably from 1.3 to 1.8.

[0029]

On the other hand, the value of A _{2 itself is the} ratio of the diameters of the second fiber, with the proviso that A ₂ is less than A ₁ , is preferably 1.1 or more, more preferably 1.2 or more, more preferably 1.3 or more and 2.0 or less, more preferably 1.9 or less, more preferably 1.8 or less. More specifically, the value of A _{2 itself of the} ratio of the diameters of the second fiber is preferably from 1.1 to 2.0, more preferably from 1.2 to 1.9, more preferably from 1.3 to 1.8.

[0030]

When the ratio A _{1 of the} diameters of the first fiber and the ratio of the diameters A _{2 of the} second fiber are regulated, the numbers P1 and P2 of the fusion-connected points on the fiber can be easily adjusted. For example, if fiber X is a two-component fiber containing core and sheath, comprising a low melting component as a shell resin and a refractory component as a core resin and having a small ratio of diameters A _X , the volume of the shell resin becomes relatively smaller than the volume of the core resin. This allows the shell resin to stretch more easily during melt spinning, and as a result, the degree of orientation of the polymer chains increases and crystallization proceeds. This leads to an increase in the softening temperature of the shell resin on the surface of the fiber (i.e., on the surface of the shell resin) and in its surrounding areas. On the other hand, if the ratio of diameters A _X is large, the volume of the shell resin approaches that of the core resin, which reduces the degree of stretching of the shell resin during melt spinning compared to the case where the ratio of diameters A _X is small. As a result, when the ratio of the diameters of A _X is large, the degree of orientation of the polymer chains becomes relatively low compared with the case where the ratio of the diameters of A _X is small; in addition, the degree of crystallization also becomes relatively small. Thus, when the diameter ratio A _X is large, the softening temperature of the shell resin on the fiber surface (i.e., on the surface of the shell resin) and in the surrounding areas becomes relatively low compared to the case where the ratio of the diameters A _X is small. The smaller the ratio of diameters A _X , the higher the softening temperature on the surface of the fiber X; thus, P1, i.e., the number of fusion-connected points on the fiber in the first fibrous layer, which includes a larger amount of fiber X having a small ratio of diameters A _X than the second fibrous layer, becomes less than P2. As described above, the softening temperature on the surface of the fiber X varies in accordance with the ratio of the diameters A _X , and this causes a difference in the degree of fusion bonding between the fibers, which makes it possible to regulate the numbers P1 and P2 of the fusion-connected points on the fiber.

[0031]

The authors of the present invention believe that the specific reason for which the softening temperature of the shell resin increases when the ratio of the diameters A _X is small is as follows. For example, in those cases where the fiber is a two-component fiber containing a core and a sheath, comprising a sheath resin made of a low melting component, and a core sheath made of a refractory component, if the ratio of the diameters A _X is small, the sheath component hardens even faster than the core component, as compared with cases where the ratio of the diameters a _X is large, when such a core and a shell comprising a bicomponent fiber made interm dstvom melt spinning. As a result, the spinning stress during melt spinning generally concentrates on the shell resin, and this causes the shell resin to tend to stretch more easily. Stretching increases the degree of orientation of the polymer chains, and also contributes to the flow of crystallization. Increasing the degree of orientation of the polymer chains in the shell resin results in an increase in the softening temperature of the shell resin. In addition, the crystallization of the polymer chains of the shell resin leads to an increase in the heat of fusion of the crystals. Due to these results, a fiber having a small ratio of diameters A _X becomes less prone to bonding by fusion, and thus the number of fusion-connected points on the fiber decreases. It should be noted that the bicomponent fibers having a small ratio of diameters A _X containing the core and the sheath have not been widely used up to now, because such fibers tend to break slightly during melt spinning and, thus, spinning is difficult.

[0032]

The authors of the present invention in their study found that by cutting a spun from a melt containing a core and a sheath of two-component fiber into short fibers and adjusting the conditions for holding short fibers appropriately, it is possible to further increase the softening temperature and increase the heat of fusion. More specifically, it has the advantage of setting the holding temperature in the range from 105 to 120 ° C, which is higher than the normal temperature. In addition, with the proviso that the aging temperature is in this range, it is advantageous to set the exposure time in the range from 1 to 3 hours, which is longer than the normal duration. In other words, it is advantageous to keep the fibers at a higher temperature for a longer time than under normal conditions. The thermal relaxation effect of the crystallized shell resin can be expected by keeping the fibers at a higher temperature for a longer time. Thermal relaxation further promotes crystallization of the shell resin.

[0033]

The authors of the present invention obtained the results presented below in Table 1 by measuring the thermophysical properties of the shell component using a differential scanning calorimeter for a core and a shell of a two-component fiber A having a diameter ratio A _{X of} 1.6 and containing the core and the shell of a two-component fiber B having a smaller diameter ratio A _{x of} 1.2. In both containing the core and sheath bicomponent fibers A and B there was a core made of polyethylene terephthalate and a sheath made of polyethylene, and the linear density was 2.3 dtex. Containing the core and sheath bicomponent fiber A was kept at 100 ° C for 30 minutes after cutting into short fibers. Containing the core and the sheath of the two-component fiber B was kept at 120 ° C for 2 hours after cutting into short fibers. The results in the table clearly show that the bicomponent fiber B containing the core and the sheath with a smaller diameter ratio A _X has a higher endothermic peak of the sheath component, and this means that the softening temperature rises. The results in the table also show that the bicomponent fiber B containing the core and the sheath B with a smaller ratio of diameters A _X has a higher heat of fusion, and this means the crystallization of polyethylene.

[0034]

[Table 1]

Containing core and sheath bicomponent fiber A Containing core and sheath bicomponent fiber B Linear density (dtex) 2.3 2.3 Shell resin Type of PE PE Diameter D1 (µm) 16.2 15.2 Core resin Type of PET PET Diameter D2 (µm) 10.3 13.0 The ratio of the diameters A _X 1.6 1.2 Endothermic peak shell resin (° C) 79.0 84.1 Melting point of shell resin (° C) 127.6 127.1 Heat of fusion shell resin (j / g) 188 257

[0035]

The softening temperature of the resin on the surface of each of the first fiber and the second fiber can be measured by nano-thermal analysis (nano-TA). In the nano-TA process, an image of a sample taken by an atomic force microscope (AFM) is obtained using a cantilever having a heating mechanism, and then the target area is heated. When a sample softens due to heating, the cantilever penetrates the sample. The softening temperature of a very small area of the sample is measured by detecting the displacement of the cantilever. When the first fiber and the second fiber are selected so that in a predetermined interval, the difference between the softening temperature S1 of the resin on the surface of the first fiber and the softening temperature S2 of the resin on the surface of the second fiber, both of which are measured according to this method, it is possible to easily adjust the numbers P1 and P2 fusion-connected points on the fiber.

[0036]

As described above, it is preferable that the first fibrous layer 11 has a multilayer structure comprising an upper layer on the side of the first surface and a lower layer on the side of the second surface, and that one or both of the upper layer and the lower layer include at least the first fiber and the second fiber. In addition, it is even more preferred that the first fibrous layer 11 includes fibers of two different types, including the first fusion-bonded fiber as the first fiber and the second fusion-connected fiber as the second fiber. In addition, it is preferable to use consisting of the core and the shell connected by the fusion of the fiber as each of the first fusion-connected fiber and the second fusion-connected fiber. In addition, it is preferred that the types of fibers differ with respect to the type of resin of the shell component between the first fiber fusion to be joined and the second fiber fusion to be joined. Alternatively, it is preferred that the types of fibers differ between the first fiber to be fusion bonded and the second fiber fusion to be bonded with respect to the volume ratio between the resins comprising the core component and the shell component when the same resins are used as the core component and the shell component. The use of two different types of fibers connected by fusion provides the difference in the ability of a compound to be fused between fibers depending on the combination of fibers, thus allowing to regulate the number of points connected on the fiber by fusion. The volume ratio can also be given as the ratio of the areas between the core component and the shell component in the fiber cross section.

[0037]

In cases of use, as the first and second fibers joined by fusing fibers with different volume ratios between the resins for the core component and the shell component, the ratio is V2 / V1 (in which V1 is the volume of the shell component, and V2 is the volume of the core component in the fusion fiber) is preferably 0.35 or more, preferably 0.6 or more, more preferably 0.8 or more, and preferably 6.0 or less, preferably 4.0 or less, f is preferably 2.5 or less. More specifically, V2 / V1 is preferably from 0.35 to 6.0, more preferably from 0.6 to 4.0, more preferably from 0.8 to 2.5. The volume ratio between the resins constituting the core component and the shell component of fiber X can also be given as the ratio of the areas between the core component and the shell component in the fiber cross section. The volume ratio of V2 / V1 between the resins that make up the core component and the shell component of fiber X is proportional to the ratio of the diameters of D2 / D1, where D2 is the diameter of the core component consisting of the refractory component, and D1 is the diameter of the shell component consisting of the low melting component. In other words, the ratio V2 / V1 is inversely proportional to the ratio of the diameters _{AX of the} fiber X. Thus, the large ratio V2 / V1 means that the ratio of the diameters _AX is small. As mentioned above, the smaller the ratio of diameters A _X , the higher the softening temperature on the surface of the fiber X. Thus, P1, i.e. the number of fusion-connected points on the fiber of the first fibrous layer, which includes a larger amount of fiber X having a small diameter ratio A _X , than the second fibrous layer, becomes smaller than P2. The fusion-bonded fiber can be a two-component concentric core and sheath, an eccentric two-component fiber containing the core and the sheath, a two-component fiber with parallel arrangement of components, etc.

[0038]

A variety of fibers can be used as the first fiber and the second fiber. For example, as described above, the second fusion bonded fiber may be present as a second fiber, the fusion bonded fiber being a fusion bonded fiber consisting of a core and a sheath, including a low melting component as its shell resin and a refractory component as its core resin. In this case, it is preferable that the second fusion-bonded fiber is present at least on the side of the second surface 112 of the first fibrous layer.

Alternatively, the second fusion-bonded fiber may be present as a second fiber, and this fusionable fiber is a fusionable fiber consisting of a core and a sheath, including low-melting polyester or low-melting polypropylene as its sheath resin. In this case, it is preferable that the second fusion-bonded fiber is present at least on the side of the second surface 112 of the first fibrous layer.

In addition, the second fusion bonded fiber may be present as a second fiber, and this fusion bonded fiber is a fusion bonded fiber consisting of a core and a sheath, including polyethylene resin as its shell resin and a resin having a higher melting point than polyethylene, as its core resin. In addition, in this case, it is preferable that the second fusion bonded fiber is present at least on the side of the second surface 112 of the first fibrous layer.

[0039]

In particular, as at least one of the first fusion-bonded fiber or the second fusion-bonded fiber, it is preferable to use a fiber selected from the group consisting of a fiber having a core and a shell structure in which the shell component is a fusible polypropylene, a fiber having a core and shell structure, in which the shell component is polyethylene, and a fiber having cores Shells and shells are a structure in which the shell component is a low-melting polyester. Preferably, the fiber is contained at least on the side of the second surface 112 of the first fibrous layer. The first fusionable fiber and the second fusionable fiber can be a two-component concentric core and sheath, an eccentric two-component fiber containing the core and sheath, a two-component fiber with a parallel arrangement of the components, etc.

[0040]

In cases where a fusion-bonded fiber is used as the first, a fiber having a core and shell structure, in which the shell component is a low-melting polypropylene, it is preferable that the fiber that is composed of a core is used as the second fusion-bonded fiber and a shell structure in which the shell component is polyethylene; or a fiber having a core and shell structure, in which the shell component is a low-melting polyester. In addition, in particular, it is preferable that the first fusion-bonded fiber is a fiber having a core and shell structure in which the shell component is low-melting polypropylene to obtain a nonwoven web having sealing ability and strength, and as a second fusion-bonded fiber uses a fiber having a core and shell structure in which the shell component is polyethylene, to get a non-woven fabric that has excellent texture and durability. Preferably, the first fusion bonded fiber and the second fusion bonded fiber are present at least on the side of the second surface 112 of the first fibrous layer.

[0041]

In the aforementioned fiber having a core and shell structure in which the shell component is low melting polypropylene, it is possible to use any known low melting polypropylene as low melting polypropylene for the shell component, without particular limitation; however, its melting point is preferably from 130 to 150 ° C. Examples of the core component include polyethylene terephthalate (melting point 250 to 270 ° C) and polypropylene (melting point 150 to 170 ° C). Regarding the ratio between the shell component and the core component, the shell component is preferably 20% by volume or more, more preferably 30% by volume or more, and preferably 80% by volume or less, more preferably 70% by volume or less and, more specifically, preferably from 20 to 80% by volume, more preferably from 30 to 70% by volume. The core component is preferably 50% by volume or more, more preferably 60% by volume or more, and preferably 80% by volume or less, more preferably 70% by volume or less and, more specifically, preferably from 50 to 80% by volume, more preferably from 60 to 70 vol.%.

[0042]

In the aforementioned fiber having a core and shell structure in which the shell component is polyethylene, it is preferable to use polyethylene having a melting point of 120 to 140 ° C. as the polyethylene for the shell component. Examples of the core component include polyethylene terephthalate (melting point 250 to 270 ° C) and polypropylene (melting point 150 to 170 ° C). Regarding the ratio between the shell component and the core component, the shell component is preferably 15% by volume or more, preferably 23% by volume or more, and preferably 75% by volume or less, more preferably 61% by volume or less and, more specifically, preferably from 15 to 75% by volume, more preferably from 23 to 75% by volume. the core component is preferably 49% by volume or more, more preferably 59% by volume or more, and preferably 85% by volume or less, more preferably 77% by volume or less and, more specifically, preferably from 49 to 85% by volume, more preferably from 59 to 77% by volume.

[0043]

In the aforementioned fiber having a core and shell structure in which the shell component is a low melting polyester, it is possible to use any known low melting polyester as a low melting polyester for the shell component without any particular limitation; however, its melting point is preferably from 100 to 150 ° C. Examples of the core component include polyethylene terephthalate (melting point 250 to 270 ° C) and polypropylene (melting point 150 to 170 ° C). Regarding the ratio between the shell component and the core component, the shell component is preferably 20% by volume or more, more preferably 30% by volume or more, and preferably 80% by volume or less, more preferably 70% by volume or less and, more specifically, preferably from 20 to 80% by volume, more preferably from 30 to 70% by volume. the core component is preferably 50% by volume or more, preferably 60% by volume or more, and preferably 80% by volume or less, more preferably 70% by volume or less and, more specifically, preferably from 50 to 80% by volume, more preferably from 60 to 70 vol.%.

[0044]

The thickness (linear density) of the first fusion-bonded fiber and the second fusion-connected fiber may be the same or different from each other, preferably 1 dtex or more, more preferably 2 dtex or more, more preferably 3 dtex or more, and preferably 15 dtex or less, more preferably 10 dtex or less, more preferably 6 dtex or less and, more specifically, preferably from 1 to 15 dtex, more preferably from 2 to 10 dtex, more preferably from 3 to 6 dtex. In addition, the first fusion-bonded fiber and the second fusion-bonded fiber, used as the first fiber and the second fiber, may be a continuous fiber made of long fiber, or a short fiber such as staple fiber. In cases where short fibers are used, the lengths of the first fiber and the second fiber may be the same or different from each other. More specifically, it is preferable that the fiber length of the first fiber and the length of the second fiber in each case independently range from 35 to 70 mm. The use of short fibers as the first fiber and / or the second fiber is preferred because the three-dimensional sheet 10 can be easily manufactured according to the manufacturing method described below.

[0045]

The mixing ratio between the first fiber fusion to be joined and the second fiber fusion to be joined is freely determined depending on the types of fibers used; the amount of the first fusion-bonded fiber is preferably from 10 to 70 wt. including in relation to 100 wt. including the total amount of the first fusion bonded fiber and the second fusion bonded fiber. More specifically, in the case of using a fiber having a core and shell structure, in which the shell component is low-melting polypropylene, as the first fusion-bonded fiber, and using a fiber having a core and shell structure, in which the shell component is a polyethylene as the second fusion bonded fiber, the amount of the first fusion bonded fiber is preferably from 10 to 70 wt. including in relation to 100 wt. including the total amount of the first fusion bonded fiber and the second fusion bonded fiber.

[0046]

The first fusion bonded fiber and the second fusion bonded fiber may be contained in the first fibrous layer 11 having a single-layer structure, or they may be contained in the first fibrous layer 11 having a multi-layer structure, for example, a two-layered structure. In the latter case, including the first fusion bonded fiber and the second fusion bonded fiber in the lower layer in the upper layer located on the side of the first surface 111 of the first fibrous layer, and the lower layer located on the side of the second surface 112 of the first fibrous layer, you can more easily satisfy the ratio of P1 and P2.

[0047]

When the first fibrous layer 11 has a two-layer structure comprising an upper layer located on the side of the first surface 111 of the first fibrous layer, and a lower layer located on the side of the second surface 112 of the first fibrous layer, it is preferable that in the first fibrous layer 11, the number S2 of fusing points on the fiber with respect to the density of the fiber on the side of the second surface 112 is less than the number S1 connected by fusing the points on the fiber with respect to the density of the fiber on the side n The first surface is 111. When S1 and S2 satisfy this ratio, the ratio of P1 and P2 can be more easily satisfied. In particular, S1 is preferably more than 100%, preferably 105% or more with respect to S2, and preferably 300% or less, preferably 125% or less with respect to S2 and, more specifically, S1 is preferably more than 100% to 300% or less, preferably from 105 to 125% with respect to S2. To achieve this ratio, it is preferable to use two or more types of the above-mentioned consisting of a core and a sheath of fusion-joined fibers as fusion-joined fibers contained in the lower layer located on the side of the second surface 112 of the first fibrous layer.

[0048]

In addition, in cases where the first fibrous layer 11 has a two-layer structure comprising an upper layer located on the side of the first surface 111 of the first fibrous layer, and a lower layer located on the side of the second surface 112 of the first fibrous layer, it is preferable that the fusion bonded fiber of the same type is contained in the upper layer and the lower layer. This improves the ability of the compound to be fused between the upper layer and the lower layer and increases the mechanical strength of the three-dimensional sheet 10.

[0049]

In addition, in cases where the first fibrous layer 11 has a two-layer structure comprising an upper layer located on the side of the first surface 111 of the first fibrous layer, and a lower layer located on the side of the second surface 112 of the first fibrous layer, it is preferable that the upper layer made only of the first fusion-bonded fiber. Thus, a rattle on the side of the first surface 111 of the first fibrous layer can be effectively suppressed. In this case, the lower layer preferably comprises fibers of a plurality of types and more preferably includes fusion-bonded fibers of many types. Fusion-bonded fibers of many types may include the first fusion-connected fiber as one of them, or they may not include the first fusion-connected fiber. In particular, it is preferable that the upper layer is made only of the first fusion bonded fiber, and that the lower layer includes a first fusion bonded fiber and a second fusion bonded fiber. This creates a favorable appearance after use, because the upper layer and lower layer are less likely to delaminate when, for example, the sheet is subjected to friction or external force during use.

[0050]

As for the second fibrous layer 12, it is preferred that the second fibrous layer 12 and the first fibrous layer 11 include a fusionable fiber of the same type. Thus, the bonding strength between the first fibrous layer 11 and the second fibrous layer 12 in the depressions 21 of the nonwoven web 10 can be further increased. Increasing the bonding strength in the depressions 21 helps to reduce the tampering on the side of the first surface 111 of the first fibrous layer. In order to further enhance this effect, it is preferred that the fusion bonded fiber contained in the lower layer located on the side of the second surface 112 of the first fibrous layer 11 is of the same type as the fusion bonded fiber contained in the second fibrous layer 12.

[0051]

For the same reason, it is also preferred that the second fibrous layer 12 includes the first fusion-bonded fiber. In particular, it is preferable that the second fibrous layer 12 includes a first fusion bonded fiber, and that the bottom layer located on the side of the second surface 112 of the first fibrous layer 11 also includes a first fusion bonded fiber.

[0052]

The first fibrous layer 11 and the second fibrous layer 12 in the three-dimensional sheet 10 can both be made, for example, from a nonwoven web. The first fibrous layer 11 may have a single layer structure or a multilayer structure. Preferably, the first fibrous layer has a multilayer structure in order to freely select the fibers included in the first fibrous layer 11. In addition, the second fibrous layer 12 may have a monolayer structure or a multilayer structure. Examples of nonwoven webs include spunbond nonwoven webs, air spun non woven webs, hydro-woven non woven webs, meltblown nonwoven webs, resin-bonded nonwoven webs, and needle punched non wovens. Non-woven webs of the same type or non-woven webs of various types can be used for the first fiber layer 11 and the second fiber layer 12.

[0053]

The surface density of the first fibrous layer 11 and the second fibrous layer 12 can be set accordingly depending on the specific application of the three-dimensional sheet 10. For example, in cases of using a three-dimensional sheet 10 as the top sheet of an absorbent article, the surface density of the first fibrous layer 11 and the surface density of the second fibrous layer layer 12 in each case independently preferably represent 3 g / m ² or more, more preferably 5 g / m ² or more, and preferably 30 g / m ² or Me , Preferably 15 g / m ² or less, and more concretely, preferably from 3 to 30 g / m ^2, preferably from 5 to 15 g / m ^2.

[0054]

The surface density of the three-dimensional sheet 10, including the first fibrous layer 11 and the second fibrous layer 12, can be set accordingly depending on the specific application of the three-dimensional sheet 10. For example, in cases of using three-dimensional sheet 10 as the top sheet of an absorbent article, the surface density of the three-dimensional sheet 10 is preferably 6 g / m ² or more, more preferably 10 g / m ² or more, and preferably 60 g / m ² or less, more preferably 30 g / m ² or less and, more specifically, a preference preferably from 6 to 60 g / m ² , more preferably from 10 to 30 g / m ² .

[0055]

In addition, the thickness of the three-dimensional sheet 10 can be set accordingly, depending on its particular application. For example, in cases where a three-dimensional sheet 10 is used as the top sheet of an absorbent article, the thickness of the three-dimensional sheet 10 is preferably 0.1 mm or more, preferably 0.2 mm or more, and preferably 5.0 mm or less, preferably 3.0 mm or less and, more specifically, preferably from 0.1 to 5.0 mm, more preferably from 0.2 to 3.0 mm. The thickness of the three-dimensional sheet 10 means the thickness in the thickest part of the three-dimensional sheet 10. The thickest part is usually located at the top of the bulge 20. The thickness is measured as follows. First, the measured three-dimensional sheet 10 is cut to obtain a cut out sample of the three-dimensional sheet 10, so that its length is 50 mm in the longitudinal direction, and the width is 50 mm in the transverse direction. The thickness of this cut out sample is measured under a pressure of 49 Pa. The environmental conditions for the measurement are a temperature of 20 ± 2 ° C and a relative humidity of 65 ± 5%. A microscope is used as a measuring device (VHX-1000 from Keyence Corporation). First get a magnified image of the cut sample. At the same time, an enlarged image of a product of a known size is obtained. The thickness of the three-dimensional sheet 10 is measured according to the scale of the enlarged image of the cut sample. The above process is carried out three times, and the average of the three dimensions is defined as the thickness (mm) of the three-dimensional sheet 10 in the dry state.

[0056]

Next, a preferred method for manufacturing the three-dimensional sheet 10 according to the present embodiment will be described. As illustrated in FIG. 4, the method of manufacturing the three-dimensional sheet 10 according to the present embodiment includes the following steps: inserting the first fiber sheet 11a into the engagement section between the first roller 31 having bulges and depressions on its circumferential surface and the second roller 32 having bulges and depressions on its circumferential surface , which engage with protuberances and depressions of the first roller 31, and a first fibrous sheet 11a is formed with protuberances and depressions; and then connecting the second fiber sheet 12a to the first fiber sheet 11a in position on the bulge 31a of the first roller 31 using the heating roller 34. The first fiber sheet 11a is a sheet serving as material for the first fiber layer 11 in a given three-dimensional sheet 10. The second the fibrous sheet 12a is a sheet that serves as a material for the second fibrous layer 12 in a given three-dimensional sheet 10. The first fibrous sheet 11a can have a single-layer structure or a multi-layer structure RU. Similarly, the second fibrous sheet 12a may have a monolayer structure or a multilayer structure. It should be noted that the manufacturing method according to the present embodiment can be implemented similarly to the method described in JP 2004-174234A (in particular, as described in paragraphs [0021] - [0025]), if other conditions are not given.

[0057]

FIG. 5 illustrates the state in which the first fiber sheet 11a is inserted into the engagement section between the first roller 31 and the second roller 32, and a sheet 11a with bumps and depressions is obtained. The first fibrous sheet 11a, inserted between two rollers 31, 32 that are in the engaged state, stretches between the protuberances 31a of the first roller 31 and the protuberances 32a of the second roller 32, and as a result, the first fibrous sheet 11a with protuberances and depressions is obtained. For example, it is appropriate to use a nonwoven web as the first fiber sheet 11a. Examples of nonwoven webs are the webs described above. The first fiber sheet 11a preferably includes the aforementioned first fusion bonded fiber and a second fusion bonded fiber. In particular, it is preferable that the first fiber sheet 11a has a two-layer structure, and that in the two-layer structure, the aforementioned first fusion-joined fiber and the second fusion-connected fiber are contained in the lower layer corresponding to the side of the second surface of the first fibrous layer 11. Furthermore, it is preferable that the first fibrous sheet 11a has a two-layer structure, and that in a two-layer structure, a fusion-bonded fiber of the same type is contained in each of the upper layer corresponding to the first side surface of the first fibrous layer 11 and lower layer corresponding to the second side surface of the first fibrous layer 11.

[0058]

In the state where bulges and depressions are formed, as illustrated in FIG. 5, the surfaces of the first fiber sheet 11a are substantially parallel. The first fibrous sheet 11a with protuberances and depressions is then connected to the second fibrous sheet. In the process of this connection, connected regions 13 are formed. The cross-sectional shape of the sheet immediately after the connection is as illustrated in FIG. 6 (a). As illustrated in the drawing, the surfaces of the first fiber sheet 11a immediately after joining are substantially parallel.

[0059]

In this way, a given three-dimensional sheet 10 is obtained. The obtained three-dimensional sheet 10 is preferably used as the top sheet of an absorbent article, which includes: an upper sheet located on the side close to the user's skin in the process of wearing; the bottom sheet, located on the side remote from the user's skin in the process of wearing; and a fluid retaining absorbent member located between the top sheet and the bottom sheet. The three-dimensional sheet 10 may also be used, for example, as a sheet located between the top sheet and the absorbent member, or a sheet for producing a leak-free cuff, in particular, a sheet for manufacturing the inner wall of a leak-free cuff. In cases where the nonwoven fabric 10 is used as the top sheet of the absorbent article, it is preferable if the first fibrous layer 11 of the nonwoven fabric 10 is positioned in such a way that it faces the user's skin. Specific examples of absorbent articles in which the nonwoven web 10 can be used include disposable diapers, sanitary napkins, pads for those suffering from incontinence and daily pads attached to underwear.

[0060]

The present invention has been described above according to its preferred embodiments. However, the present invention is not limited to the above embodiments. For example, according to the aforementioned embodiment, each bulge of the three-dimensional sheet 10 has the shape of an almost hemispherical shell, but, as an alternative, the bulge may have the shape of an almost rectangular parallelepiped, as described, for example, in patent document 1.

[0061]

In relation to the above embodiments, the present invention further describes the following three-dimensional sheets, upper sheets for absorbent articles and absorbent articles.

{1} Three-dimensional sheet, including:

a first fibrous layer comprising a first surface and a second surface opposite to it; and

the second fibrous layer comprising the first surface and the opposite second surface, and:

the first and second fibrous layers are layered in such a way that the second surface of the first fibrous layer faces the first surface of the second fibrous layer;

the joined regions are formed by partially joining by fusing the first fibrous layer and the second fibrous layer, and, between the joined regions, the first fibrous layer projects in the direction of separation from the second fibrous layer to form a plurality of protuberances;

each of the first fibrous layer and the second fibrous layer is made of a nonwoven fabric;

the first fibrous layer includes fibers of many types;

fibers of many types include at least two types of fibers, including the first fiber and the second fiber;

each of the first fiber and the second fiber includes a refractory component and a low-melting component; and

the ratio of the diameters, when calculated according to the following equation, between the refractory component and the low-melting component of the first fiber differs from the ratio of the diameters between the refractory component and the low-melting component of the second fiber:

the ratio of the diameters between the refractory component and the low-melting component (A _X ) = the diameter of the low-melting component of the fiber X (D1) / the diameter of the refractory component of the fiber X (D2).

[0062]

{2} The three-dimensional sheet of {1}, in which:

the first fibrous layer has a multilayer structure comprising an upper layer on the side of the first surface and a lower layer on the side of the second surface; and

one or both of the top layer and the bottom layer include fibers of a variety of types.

{3} The three-dimensional sheet according to {1} or {2}, in which the A ₂ / A ₁ value of the A ₂ and A ₁ ratio is preferably less than 1, preferably 0.99 or less, more preferably 0.91 or less .

{4} Three-dimensional sheet according to any one of paragraphs. {1} - {3}, in which the value of A ₂ / A ₁ is preferably 0.5 or more, more preferably 0.6 or more, more preferably 0.7 or more.

{5} Three-dimensional sheet according to any one of paragraphs. {1} - {4}, in which the value of A ₁ ratio of the diameters of the first fiber is preferably 1.1 or more, preferably 1.2 or more, more preferably 1.3 or more.

{6} Three-dimensional sheet according to any one of paragraphs. {1} - {5}, in which the value of A ₁ ratio of the diameters of the first fiber is preferably 2.0 or less, preferably 1.9 or less, more preferably 1.8 or less.

{7} Three-dimensional sheet according to any one of paragraphs. {1} - {6}, in which the value of A _{2 is the} ratio of the diameters of the second fiber, with the proviso that A ₂ is less than A ₁ , is preferably 1.1 or more, more preferably 1.2 or more, more preferably 1 3 or more.

[0063]

{8} Three-dimensional sheet according to any one of paragraphs. {1} - {7}, in which the value of A _{2 is the} ratio of the diameters of the second fiber, provided that A2 is less than A ₁ , is preferably 2.0 or less, more preferably 1.9 or less, more preferably 1, 8 or less.

{9} Three-dimensional sheet according to any one of paragraphs. {1} - {8}, in which the first fibrous layer and the second fibrous layer include fusion-bonded fiber of the same type.

{10} Three-dimensional sheet according to any one of paragraphs. {1} - {9}, in which the side of the second surface of the first fibrous layer includes the first fiber and the second fiber.

{11} Three-dimensional sheet according to any one of paragraphs. {1} - {10}, in which:

the first fiber layer includes fibers of many types, including the first fiber and the second fiber, and the first fusion-bonded fiber is included as the first fiber; and

the second fibrous layer also includes a first fusion bonded fiber.

{12} Three-dimensional sheet according to any one of paragraphs. {1} - {11}, in which the upper layer on the side of the first surface and the lower layer on the side of the second surface of the first fibrous layer include fusion-bonded fiber of the same type.

{13} Three-dimensional sheet according to any one of paragraphs. {1} - {12}, in which:

the first fiber layer includes fibers of many types, including the first fiber and the second fiber, and the first fusion-bonded fiber is included as the first fiber; and

the first fibrous layer has a two-layer structure, and the upper layer on the side of the first surface of the first fibrous layer is made only of the first fusion-bonded fiber.

[0064]

{14} The three-dimensional sheet according to {11} or {13}, in which the second fiber is a short fiber.

{15} Three-dimensional sheet according to any one of paragraphs. {1} - {14}, in which:

the second fusion bonded fiber is included as second fiber; and

the second fusion bonded fiber is contained at least on the side of the second surface of the first fibrous layer.

{16} Three-dimensional sheet according to any one of paragraphs. {1} - {15}, in which:

multiple types of fibers include first fiber and second fiber;

the second fusion bonded fiber is included as second fiber; and

the second fusion bonded fiber is a fusion bonded fiber consisting of a core and a sheath, in which the shell resin is a low melting component and the core resin is a refractory component.

{17} The three-dimensional sheet according to {16}, in which the shell resin in the second fusion-bonded fiber is a polyethylene resin.

{18} The three-dimensional sheet according to {16}, in which the shell resin in the second fusion-bonded fiber is a low-melting polyester or low-melting polypropylene.

[0065]

{19} Three-dimensional sheet according to any one of paragraphs. {15} - {18}, in which the mixing ratio between the first fusion to be joined by fiber and the second to be connected by fusion by fiber is preferably set in such a way that the first fusionable fiber is from 10 to 70 wt. including in relation to 100 wt. including the total amount of the first fusion bonded fiber and the second fusion bonded fiber.

{20} Three-dimensional sheet according to any one of paragraphs. {1} - {19}, in which, when P1 is the average value of the number S1 of the fusion-connected points on the fiber relative to the fiber density on the first surface of the first fiber layer and the number S2 of the fusion-connected points on the fiber relative to the density of the fiber on the side of the second surface of the first fibrous layer, and P2 is the number of fusion-connected points on the fiber with respect to the fiber density on the side of the first surface of the second fibrous layer, P1 is less than P2.

{21} The three-dimensional sheet according to {20}, in which P1 is preferably 55% or more, more preferably 65% or more with respect to P2.

{22} The three-dimensional sheet according to {20} or {21}, in which P1 is preferably 95% or less, more preferably 85% or less with respect to P2.

{23} Three-dimensional sheet according to any one of paragraphs. {20} - {22}, in which the P1 value is preferably 150 points / mm ³ or more, preferably 175 points / mm ³ or more, and preferably 240 points / mm ³ or less, more preferably 215 points / mm ³ or less.

[0066]

{24} Three-dimensional sheet according to any one of paragraphs. {20} - {23}, in which the value of P2, with the proviso that P2 is larger than P1, is preferably 220 points / mm ³ or more, preferably 240 points / mm ³ or more, and preferably 300 points / mm ³ or less, preferably 280 points / mm ³ or less.

{25} Three-dimensional sheet according to any one of paragraphs. {20} - {24}, in which the fiber density, serving as the basis for calculating P1 and P2, is the mass of the nonwoven web relative to unit volume, and µg / mm ^{3 is} used as the unit density of the fiber.

{26} Three-dimensional sheet according to any one of paragraphs. {20} - {25}, in which:

in the case where the first fibrous layer has a two-layer structure, the fiber density on the side of the first surface of the first fibrous layer means the density of the fiber layer located on the top side; and

in the case where the first fibrous layer has a two-layer structure, the fiber density on the side of the second surface of the first fibrous layer means the density of the fiber layer located on the side of the second fibrous layer.

{27} Three-dimensional sheet according to any one of paragraphs. {20} - {26}, in which:

in the case where the second fibrous layer has a monolayer structure, the fiber density on the side of the first surface of the second fibrous layer means the fiber density of the part located on the side of the first fibrous layer when the thickness of the first fibrous layer is halved; and

in the case where the second fibrous layer has a two-layer structure, the fiber density on the side of the first surface of the second fibrous layer means the density of the fiber layer located on the side of the first fibrous layer.

{28} Three-dimensional sheet according to any one of paragraphs. {20} - {27}, in which the number of fusion-connected points on a fiber means the number of fusion-connected points per fiber and is determined by the unit "the number of points / fiber".

[0067]

{29} Three-dimensional sheet according to any one of paragraphs. {20} - {28}, in which, in the first fibrous layer, the number S2 of the fusion-connected points on the fiber with respect to the fiber density on the second surface is less than the number S1 of the fusion-connected points on the fiber with respect to the fiber density on the side first surface.

{30} Three-dimensional sheet according to any one of paragraphs. {20} - {29}, in which S1 is preferably more than 100%, more preferably 105% or more with respect to S2.

{31} Three-dimensional sheet according to any one of paragraphs. {20} - {30}, in which S1 is preferably 300% or less, more preferably 125% or less with respect to S2.

{32} Absorbent article using a three-dimensional sheet according to any one of paragraphs. {1} - {31}.

{33} Absorbent article using a three-dimensional sheet according to any one of paragraphs. {1} - {31} so that the first fibrous layer is facing the user's skin.

Examples

[0068]

The present invention will be described in detail below by way of examples. However, the scope of the present invention is not limited to these examples.

[0069]

{Example 1}

The three-dimensional sheet 10, which is illustrated in FIG. 1 and 2, was manufactured using a device of the same type as illustrated in FIG. 2-6 applications JP 2004-174234A. In the first fiber sheet 11a serving as the material of the first fiber layer 11 of the three-dimensional sheet 10, fiber (1) and fiber (2) were used for the first surface side, and fiber (3) and fiber (4) were used for the second surface side . Fiber (1) was a core and sheath containing fiber having a core of polyethylene terephthalate (PET) and a sheath of polyethylene (PE), and having a linear density of 2.3 dtex, a core diameter of D2 10.30 µm and a diameter of the shell 16,18 um The ratio of A1 diameters of the core and the shell (shell / core) was 1.57. Details regarding the fibers (2), (3) and (4) are presented below in Table 2. The first fiber sheet 11a was a pneumatic woven nonwoven web having a two-layer structure (surface density: 18 g / m ² ). For the second fibrous sheet 12a, serving as the material of the second fibrous layer 12 in the three-dimensional sheet 10, a pneumatic-woven nonwoven fabric (surface density: 18 g / m ² ) having a fiber composition, presented in Table 2 below was used. It should be noted that all the fibers used in this example were short fibers (fiber length: 51 mm). Thus, a given three-dimensional sheet was obtained.

[0070]

{Example 2}

In this example, the specified three-dimensional sheet was obtained in the same manner as in example 1, except that the fiber composition on the side of the second surface 112 of the first fiber sheet 11a, which has a two-layer structure, was different from the fiber composition in example 1, as shown in table 2 ..

[0071]

{Example 3}

In this example, the specified three-dimensional sheet was obtained in the same manner as in Example 1, except that a pneumatic woven nonwoven fabric was used as the first fiber sheet 11a having a two-layer structure, which includes fusion-joined fibers of two types on the first surface side 111 and additionally includes fusion bonded fiber of the same type on the side of the second surface 112, as shown in Table 2.

[0072]

{Example 4}

In this example, the specified three-dimensional sheet was obtained in the same manner as in Example 1, except that the air spun nonwoven web having a single layer structure was used as the first fiber sheet 11a, and this air spun nonwoven web includes two types of fusionable fiber as constituent fibers, as presented in table 2.

[0073]

{Examples 5 and 6}

In each of these examples, the specified three-dimensional sheet was obtained in the same manner as in example 1, except that the types of fibers on the side of the second surface 112 of the first fiber sheet 11a having a two-layer structure differed from the types of fibers in example 1, as represented in table 2.

[0074]

{Examples 7 and 8}

In each of these examples, the specified three-dimensional sheet was obtained in the same manner as in Example 6, except that the ratio between the fibers used on the side of the second surface 112 of the first fiber sheet 11a having a two-layer structure was different from the ratio in Example 6, as presented in table 2.

[0075]

{Examples 9 and 10}

In each of these examples, the specified three-dimensional sheet was obtained in the same manner as in Example 6, except that the ratio between the core and the shell components in the fiber (4), which was a fiber on the side of the second surface 112 of the first fiber sheet 11a, having a two-layer structure, different from the ratio in example 6, as presented in table 2 ..

[0076]

{Example 11}

In this example, the specified three-dimensional sheet was obtained in the same manner as in Example 1, except that the air spun nonwoven web having a single layer structure was used as the first fiber sheet 11a, and this air spliced non woven web includes two types of fusion-bonded fiber as constituent fibers, as presented in table 2 ..

[0077]

{Comparative example 1}

As presented in Table 3, in this comparative example, a flat, air-woven nonwoven web consisting of only the first fiber layer 11 was made using only the first fiber sheet 11a of Example 1 without the second fiber sheet 12a. This air spun nonwoven web corresponds to the non woven web described in Patent Document 3.

[0078]

{Comparative example 2}

In this comparative example, the sheet was obtained in the same manner as in Example 1, except that the air spun nonwoven web having a single layer structure was used as the first fiber sheet 11a, and this air spun nonwoven web includes fusion bonded fiber of one type in as constituent fibers, as presented in table 3. The sheet obtained in this comparative example corresponds to the sheet described in patent document 1.

[0079]

{Comparative example 3}

In this example, the sheet was obtained in the same manner as in Example 1, except that only one fiber type was used as the fiber on the side of the second surface 112 of the first fiber sheet 11a having a two-layer structure as shown in Table 3. Sheet , obtained in this comparative example, corresponds to the sheet described in Patent Document 2, and its convexities have a solid structure.

[0080]

{Evaluation}

The thickness, fiber density and the number of fusion-joined points for each fiber layer were measured according to the methods described above for each of the sheets obtained in the examples and comparative examples. The ratio of the number of points connected by fusion and the density of the fiber was also calculated. To measure the number of points connected by fusion, images were taken with a scanning electron microscope, as illustrated in FIG. 9 (example 7) and FIG. 10 (comparative example 2). In these images, the areas circled are fusion-connected points. In addition, the resistance to the loss of jagged fibers, the smoothness on the first surface of the first fibrous layer, the feeling of cushioning of the sheet, the slight irritation of the skin caused by the sheet, and the texture were measured and evaluated according to the following methods. The results are presented in tables 4 and 5.

[0081]

{Resistance to the loss of ruffled fibers}

A test specimen having 200 mm in the X direction (transverse direction) and 200 mm in the Y direction (longitudinal direction) were cut from each nonwoven web obtained in Examples 1-11 and Comparative Examples 1-3, and one surface of the test specimen was used as surface for evaluation. More specifically, the four sides of the test specimen were attached to the plate with a packing tape, with the estimated surface facing upwards. A friction plate with a sponge wrapped around it (Moltoprene MF-30) was installed on the sample under test. The mass of the sponge was 240 g. The friction plate was rotated, and the sample under study made 15 series of rotations, in which one series consisted of three turns forward and three turns back. As for the speed of each rotation, one revolution took 3 seconds. After that, all the fibers that were attached to the sponge were glued to a transparent adhesive tape. The tape was then attached to a black matte board. According to the state of the surface of the sample and the fibers attached to the adhesive tape, the degree of deposited fuzzy fibers was assessed by visual observation according to the following criteria.

The ideal score was 5 points, while there was absolutely no loss of jagged fibers. For each dropped out freaked-out fiber, 55 points were deducted from 5 points. If 16 or more jagged fibers were present, the score was 1 point. States with appropriate ratings are usually described as follows.

5 points: There is almost no staggering and rolling into nodules on the test sample. There are almost no fibers attached to the adhesive tape.

4 points: A rattle is observed on the test specimen, but there is almost no rolling into the nodules. There are almost no fibers attached to the adhesive tape.

3 points: Rumping or rolling into nodules is observed on the test sample, but no mass of fibers is observed on the adhesive tape.

1 point: Rumping or rolling into nodules is observed on the test specimen, and a considerable mass of fibers is observed on the adhesive tape.

[0082]

{Smoothness}

The friction coefficient MMD of the first surface of the first fiber layer was measured using a KES-FB4-AUTO-A automatic surface research instrument from Kato Tech Co., Ltd.

[0083]

{Feeling depreciation}

The WC compression energy per 1 cm ^{2 was} measured using an automatic compression testing device KES-FB3-AUTO-A from Kato Tech Co., Ltd.

[0084]

{Insignificance of skin irritation with a leaf}

A three-dimensional sheet 10 was attached to the terminal, and the upper part of the tester's hand was rubbed with a sheet under a load of 3.0 kPa, moving the sheet back and forth within the friction region of 40 mm. In addition, each reciprocating movement took 1 second. The feeling of the hand after 500 movements was evaluated on the following three-point scale.

A: The tester does not feel pain or has a pleasant sensation.

B: the tester does not feel irritation.

C: The tester feels irritation and pain.

[0085]

{Texture}

The texture of the sheet was evaluated blindly by 10 people, and the texture of the sheet according to comparative example 2 was estimated at 5 points. The average rating of 10 people was taken as a texture evaluation.

[0086]

[Table 2]

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 The first fibrous layer Side of the first surface Fiber (2) The mass ratio of the resin core / shell Missing Missing PP / low melting PP
5: 5 Missing Missing Missing Missing Missing Missing Missing PET / PE
6-4 Linear density (dtex) - - 2.2 2.2 - - - - - - 2.3 The diameter of the core D2 (μm) - - 12.41 12.41 - - - - - - 11.28 The diameter of the shell D1 (μm) - - 17.59 17.59 - - - - - - 15.87 The ratio of A2 diameters of the core and the shell (shell / core) - - 1.42 1.42 - - - - - - 1.41 Mass ratio (%) of fiber (1) and fiber (2) - - 50:50 50:50 - - - - - - 50:50 The ratio of fiber diameter (2) and fiber diameter (1) - - 0.90 0.90 - - - - - - 0.90 Side of the second surface Fiber (3) The mass ratio of the resin core / shell PET / PE
5: 5 PET / PE
5: 5 PET / PE
5: 5 PET / PE
5: 5 PP / low melting PP
4: 6 PET / PE
5: 5 PET / PE
5: 5 PET / PE
5: 5 PET / PE
5: 5 PET / PE
5: 5 PET / PE
5: 5 Linear density (dtex) 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 The diameter of the core D2 (μm) 10.30 10.30 10.30 10.30 10.30 10.30 10.30 10.30 10.30 10.30 10.30 The diameter of the shell D1 (μm) 16,18 16,18 16,18 16,18 16,18 16,18 16,18 16,18 16,18 16,18 16,18 The ratio of A1 diameters of the core and the shell (shell / core) 1.57 1.57 1.57 1.57 1.57 1.57 1.57 1.57 1.57 1.57 1.57 Fiber (4) The mass ratio of the resin core / shell PP / low melting PP
5: 5 PP / low melting PP
5: 5 Missing PP / low melting PP
5: 5 PP / low melting PP
4: 6 PET / PE
8: 2 PET / PE
8: 2 PET / PE
8: 2 PET / PE
7: 3 PET / PE
6-4 PET / PE
6-4 Linear density (dtex) 2.2 2.2 - 2.2 2.2 2.3 2.3 2.3 2.3 2.3 2.3 The diameter of the core D2 (μm) 12.41 12.41 - 12.41 13.59 13.03 13.03 13.03 12,19 11.28 11.28 The diameter of the shell D1 (μm) 17.59 17.59 - 17.59 17.58 15.23 15.23 15.23 15.56 15.87 15.87 The ratio of A2 diameters of the core and the shell (shell / core) 1.42 1.42 - 1.42 1.29 1.17 1.17 1.17 1.28 1.41 1.41 Mass ratio (%) of fiber (3) and fiber (4) 50:50 70:30 - 50:50 50:50 50:50 70:30 90:10 50:50 50:50 50:50 The ratio of fiber diameter (4) and fiber diameter (3) 0.90 0.90 - 0.90 0.82 0.74 0.74 0.74 0.81 0.90 0.90 Second fibrous layer Fiber The mass ratio of the resin core / shell PET / PE
5: 5 PET / PE
5: 5 PET / PE
5: 5 PET / PE
5: 5 PET / PE
5: 5 PET / PE
5: 5 PET / PE
5: 5 PET / PE
5: 5 PET / PE
5: 5 PET / PE
5: 5 PET / PE
5: 5 Mass ratio (%) of the first and second 100: 0 100: 0 100: 0 100: 0 100: 0 100: 0 100: 0 100: 0 100: 0 100: 0 100: 0

[0087]

[Table 3]

Comparative Example 1 Comparative Example 2 Comparative example 3 The first fibrous layer Side of the first surface Fiber (2) The mass ratio of the resin core / shell PP / low melting PP
5: 5 Missing Missing Linear density (dtex) 2.2 - - The diameter of the core D2 (μm) 12.41 - - The diameter of the shell D1 (μm) 17.59 - - The ratio of A2 diameters of the core and the shell (shell / core) 1.42 - - Mass ratio (%) of fiber (1) and fiber (2) 50:50 - - The ratio of fiber diameter (2) and fiber diameter (1) 0.90 - - Side of the second surface Fiber (3) The mass ratio of the resin core / shell PET / PE
5: 5 PET / PE
5: 5 PET Linear density (dtex) 2.3 2.3 2.3 The diameter of the core D2 (μm) 10.30 10.30 14.57 The diameter of the shell D1 (μm) 16,18 16,18 14.57 The ratio of A1 diameters of the core and the shell (shell / core) 1.57 1.57 1.00 Fiber (4) The mass ratio of the resin core / shell PP / low melting PP
5: 5 Missing Missing Linear density (dtex) 2.2 - - The diameter of the core D2 (μm) 12.41 - - The diameter of the shell D1 (μm) 17.59 - - The ratio of A2 diameters of the core and the shell (shell / core) 1.42 - - Mass ratio (%) of fiber (4) and fiber (3) 50:50 - - The ratio of fiber diameter (3) and fiber diameter (4) 0.9 - - Second fibrous layer Fiber The mass ratio of the resin core / shell Missing PET / PE
5: 5 PET / PE
5: 5 Mass ratio (%) of the first and second - 100: 0 100: 0

[0088]

[Table 4]

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Inner space of the bulge Present Present Present Present Present Present The side of the first surface of the first fibrous layer Thickness (mm) 0.25 0.24 0.31 0.27 0.23 0.26 Fiber density (µg / mm ³ ) 24.0 25.0 19.4 22.2 26.1 23.1 The number of points connected by fusion (points / fiber) 127 125 81 83 128 129 The mass of one fiber (µg / fiber) 11.73 11.73 11.48 11.48 11.73 11.73 The number of points connected by fusion / fiber density (points / mm ³ ) 259.85 266.41 136.56 160.67 284.67 253.79 The side of the second surface of the first fibrous layer Thickness (mm) 0.75 0.71 0.48 0.54 0.72 0.61 Fiber density (µg / mm ³ ) 16,0 16.9 21.8 22.2 16.7 19.7 The number of points connected by fusion (points / fiber) 65 73 68 72 68 81 The mass of one fiber (µg / fiber) 11.48 11.58 11.73 11.48 11.48 11.73 The number of points connected by fusion / fiber density (points / mm ³ ) 90,59 106.55 126.38 139.37 98.72 135.84 Average value The number of points connected by fusion / fiber density, P1 175.22 186.48 131.37 150.02 191.69 194.82 The side of the first surface of the second fibrous layer Thickness (mm) 0.77 0.75 0.72 0.73 0.74 0.77 Fiber density (µg / mm ³ ) 23.4 24.0 25.0 24.7 24.3 23.4 The number of points connected by fusion (points / fiber) 128 127 122 126 126 128 The mass of one fiber (µg / fiber) 11.73 11.73 11.73 11.73 11.73 11.73 The number of points connected by fusion / fiber density, P2 (points / mm ³ ) 255.09 259.85 260.02 264.86 261.28 255.09 Evaluation Loss of tattered fibers 4.25 4.50 3.75 4.00 4.25 5.00 Smoothness (MMD × 10 ^-3 ) 9.8 15.4 8,8 9.2 10.2 9.6 Sensation of depreciation (WC × 10 ^-3 ) 369 385 355 323 373 378 Slight skin irritation A B A B A A Texture (organoleptic) 11.0 9.0 8.6 10.8 9.9 10.9

[Table 4 (continued)]

Example 7 Example 8 Example 9 Example 10 Example 11 Inner space of the bulge Present Present Present Present Present The side of the first surface of the first fibrous layer Thickness (mm) 0.25 0.22 0.23 0.21 0.29 Fiber density (µg / mm ³ ) 24.0 27.3 26.1 28.6 20.7 The number of points connected by fusion (points / fiber) 125 129 128 127 94 The mass of one fiber (µg / fiber) 11.73 11.73 11.73 11.73 11.73 The number of points connected by fusion / fiber density (points / mm ³ ) 255.75 299.93 284.67 309.34 165.80 The side of the second surface of the first fibrous layer Thickness (mm) 0.71 0.68 0,69 0.63 0.52 Fiber density (µg / mm ³ ) 16.9 17.6 17.4 19.0 23.1 The number of points connected by fusion (points / fiber) 70 81 74 75 74 The mass of one fiber (µg / fiber) 11.73 11.73 11.73 11.73 11.73 The number of points connected by fusion / fiber density (points / mm ³ ) 100.86 121.86 109.71 121.79 145.58 Average value The number of points connected by fusion / fiber density, P1 178.31 210.89 197.19 215.56 155,69 The side of the first surface of the second fibrous layer Thickness (mm) 0.75 0.76 0.74 0.77 0.76 Fiber density (µg / mm ³ ) 24.0 23.7 24.3 23.4 23.7 The number of points connected by fusion (points / fiber) 125 127 123 124 124 The mass of one fiber (µg / fiber) 11.73 11.73 11.73 11.73 11.73 The number of points connected by fusion / fiber density, P2 (points / mm ³ ) 255.75 256.43 255.06 247.12 250.37 Evaluation Loss of tattered fibers 4.75 5.00 5.00 4.75 4.25 Smoothness (MMD × 10 ^-3 ) 9.7 10.2 12.2 14.1 9.9 Sensation of depreciation (WC × 10 ^-3 ) 358 341 327 311 338 Slight skin irritation A B B B A Texture (organoleptic) 10.7 8.9 8.7 8.1 10.5

[0089]

[Table 5]

Comparative Example 1 Comparative Example 2 Comparative example 3 Inner space of the bulge Missing Present Missing The side of the first surface of the first fibrous layer Thickness (mm) 0.28 0.26 0.25 Fiber density (µg / mm ³ ) 21.4 23.1 24.0 The number of points connected by fusion (points / fiber) 81 127 125 The mass of one fiber (µg / fiber) 11.48 11.73 11.73 The number of points connected by fusion / fiber density (points / mm ³ ) 151.19 249.85 255.75 The side of the second surface of the first fibrous layer Thickness (mm) 0.56 0.51 1.12 Fiber density (µg / mm ³ ) 21.4 23.5 10.7 The number of points connected by fusion (points / fiber) 70 117 0 The mass of one fiber (µg / fiber) 11.48 11.73 11.73 The number of points connected by fusion / fiber density (points / mm ³ ) 130.66 234.69 0.00 Average value The number of points connected by fusion / fiber density, P1 140.93 242.27 127,88 The side of the first surface of the second fibrous layer Thickness (mm) 0.75 0.74 Fiber density (µg / mm ³ ) 24.0 24.3 The number of points connected by fusion (points / fiber) 120 122 The mass of one fiber (µg / fiber) 11.73 11.73 The number of points connected by fusion / fiber density, P2 (points / mm ³ ) 245.52 252,99 Evaluation Loss of tattered fibers 3.75 4.50 1.00 Smoothness (MMD × 10 ^-3 ) 8.6 25.5 6.1 Sensation of depreciation (WC × 10 ^-3 ) 207 405 289 Slight skin irritation C C C Texture (organoleptic) 7.1 5.0 9.8

[0090]

The results in tables 2-5 clearly show that the three-dimensional sheets obtained according to the examples have a lower coefficient of friction on the surface with bumps and depressions and, thus, are smoother than the sheet obtained according to comparative example 2. The results also show that the three-dimensional The sheets obtained according to the examples cause less irritation of the skin and create a better cushioning feeling and a better texture than the sheets obtained according to comparative examples.

Industrial Applicability

[0091]

As described in detail above, the three-dimensional sheet according to the present invention creates a cushioning feeling due to the protuberances and has an improved smoothness of the protuberances. In addition, the three-dimensional sheet according to the present invention is improved with respect to the stability of the protuberances and the resistance of the protuberances to crushing under the influence of the load.

Claims (93)

1. A three-dimensional sheet, including: a first fibrous layer comprising a first surface and a second surface opposite to it; and the second fibrous layer comprising the first surface and the opposite second surface, and: the first and second fibrous layers are layered in such a way that the second surface of the first fibrous layer faces the first surface of the second fibrous layer; wherein by partially joining the first fibrous layer and the second fibrous layer by fusing, connected regions are formed, with the first fibrous layer between the joined regions acting in the direction of separation from the second fibrous layer with the formation of a plurality of protuberances; each of the first fibrous layer and the second fibrous layer is made of a nonwoven fabric; the first fibrous layer includes at least two types of fibers including the first fiber and the second fiber; each of the first fiber and the second fiber includes a refractory component and a low-melting component; and the diameter ratio, as determined by the following expression, between the refractory component and the low-melting component of the first fiber is different from the ratio of the diameters between the refractory component and the low-melting component of the second fiber, and the value A2 of the ratio of the diameters of the second fiber is from 1.1 to 1.2; moreover, the expression is A _X = D1 / D2, where A _X is the diameter ratio between the refractory component and the fusible component of the fiber X, D1 is the diameter of the fusible component of the fiber X, D2 is the diameter of the refractory component of the fiber X. 2. The three-dimensional sheet according to claim 1, in which: the first fibrous layer has a multilayer structure comprising an upper layer on the side of the first surface and a lower layer on the side of the second surface; and one or both of the top layer on the side of the first surface and the bottom layer on the side of the second surface include fibers of a plurality of types. 3. Three-dimensional sheet, including: a first fibrous layer comprising a first surface and a second surface opposite to it; and the second fibrous layer comprising the first surface and the opposite second surface, and: the first and second fibrous layers are layered in such a way that the second surface of the first fibrous layer faces the first surface of the second fibrous layer; moreover, by partially joining the first fibrous layer and the second fibrous layer by fusion, interconnected areas are formed between the interconnected areas, the first fibrous layer projects in the direction of separation from the second fibrous layer with the formation of a plurality of convexes; each of the first fibrous layer and the second fibrous layer is made of a nonwoven fabric; the first fibrous layer includes at least two types of fibers including the first fiber and the second fiber; the first fibrous layer has a multilayer structure comprising an upper layer on the side of the first surface and a lower layer on the side of the second surface, with one of the layers comprising fibers of many types; each of the first fiber and the second fiber includes a refractory component and a low-melting component; and the diameter ratio, as determined by the following expression, between the refractory component and the low-melting component of the first fiber is different from the ratio of the diameters between the refractory component and the low-melting component of the second fiber; moreover, the expression is A _X = D1 / D2, where A _X is the diameter ratio between the refractory component and the fusible component of the fiber X, D1 is the diameter of the fusible component of the fiber X, D2 is the diameter of the refractory component of the fiber X. 4. Three-dimensional sheet, including: a first fibrous layer comprising a first surface and a second surface opposite to it; and the second fibrous layer comprising the first surface and the opposite second surface, and: the first and second fibrous layers are layered in such a way that the second surface of the first fibrous layer faces the first surface of the second fibrous layer; by joining together by fusing the first fibrous layer and the second fibrous layer, connected regions are formed, with the first fibrous layer protruding between the joined regions in the direction of separation from the second fibrous layer with the formation of a plurality of protuberances; each of the first fibrous layer and the second fibrous layer is made of a nonwoven fabric; the first fibrous layer includes at least two types of fibers including the first fiber and the second fiber; the first fibrous layer has a multilayer structure comprising an upper layer on the side of the first surface and a lower layer on the side of the second surface, with one of the layers comprising fibers of many types, and the other layer comprising only one type of fiber; each of the first fiber and the second fiber includes a refractory component and a low-melting component; and the diameter ratio, as determined by the following expression, between the refractory component and the low-melting component of the first fiber is different from the ratio of the diameters between the refractory component and the low-melting component of the second fiber; moreover, the expression is A _X = D1 / D2, where A _X is the diameter ratio between the refractory component and the fusible component of the fiber X, D1 is the diameter of the fusible component of the fiber X, D2 is the diameter of the refractory component of the fiber X. 5. The three-dimensional sheet according to claim 3 or 4, in which the value of A _{2 the} ratio of the diameters of the second fiber, provided that A ₂ is less than the ratio A _{1 of the} diameters of the first fiber, is preferably 1.1 or more, more preferably 1, 2 or more, more preferably 1.3 or more. 6. The three-dimensional sheet according to claim 3 or 4, in which the value of A _{2 the} ratio of the diameters of the second fiber, provided that A ₂ is less than the ratio A _{1 of the} diameters of the first fiber, is preferably 2.0 or less, preferably 1, 9 or less, more preferably 1.8 or less. 7. The three-dimensional sheet according to claim 1, 3 or 4, in which: the first fiber has a larger diameter ratio than the second fiber; and the second fiber is contained at least in the lower layer on the side of the second surface. 8. Three-dimensional sheet, including: a first fibrous layer comprising a first surface and a second surface opposite to it; and the second fibrous layer comprising the first surface and the opposite second surface, and: the first and second fibrous layers are layered in such a way that the second surface of the first fibrous layer faces the first surface of the second fibrous layer; by joining together by fusing the first fibrous layer and the second fibrous layer, joined regions are formed, with the first fibrous layer between the joined regions acting in the direction of separation from the second fibrous layer with the formation of a plurality of protuberances; each of the first fibrous layer and the second fibrous layer is made of a nonwoven fabric; the first fibrous layer includes at least two types of fibers including the first fiber and the second fiber; the first fibrous layer has a multilayer structure comprising an upper layer on the side of the first surface and a lower layer on the side of the second surface; the bottom layer on the side of the second surface includes a first fiber and a second fiber; each of the first fiber and the second fiber includes a refractory component and a low-melting component; and the value A _{1 of} the diameter ratio between the refractory component and the low-melting component of the first fiber is from 1.3 to 2.0, and the value of A _{2 the} ratio of the diameters between the refractory component and the low-melting component of the second fiber is from 1.1 to 1.8, provided that that A ₂ is less than A ₁ , and the ratio of the diameters is determined by the following expression; moreover, the expression is A _X = D1 / D2, where A _X is the diameter ratio between the refractory component and the fusible component of the fiber X, D1 is the diameter of the fusible component of the fiber X, D2 is the diameter of the refractory component of the fiber X. 9. Three-dimensional sheet of PP. 1, 3, 4 or 8, in which the value of the ratio A ₂ / A ₁ (the ratio A _{2 of the} diameters of the second fiber and the ratio A _{1 of the} diameters of the first fiber) is preferably less than 1, preferably 0.99 or less, more preferably 0.91 or less. 10. Three-dimensional sheet of PP. 1, 3, 4 or 8, in which the value of the ratio A ₂ / A ₁ (the ratio A _{2 of the} diameters of the second fiber and the ratio A _{1 of the} diameters of the first fiber) is preferably 0.5 or more, preferably 0.6 or more, more preferably 0 , 7 or more. 11. Three-dimensional sheet of PP. 1, 3, 4 or 8, in which the value A _{1 of the} ratio of the diameters of the first fiber is preferably 1.1 or more, preferably 1.2 or more, more preferably 1.3 or more. 12. Three-dimensional sheet of PP. 1, 3, 4 or 8, in which the value of A _{1 the} ratio of the diameters of the first fiber is preferably 2.0 or less, preferably 1.9 or less, more preferably 1.8 or less. 13. Three-dimensional sheet of paragraphs. 1, 3, 4, or 8, in which the first fibrous layer and the second fibrous layer comprise fusion-bonded fibers of the same type. 14. Three-dimensional sheet of paragraphs. 1, 3, 4 or 8, in which: the first fiber has a larger diameter ratio than the second fiber; and the second fibrous layer comprises a first fiber. 15. Three-dimensional sheet of PP. 2, 3, 4, or 8, in which the upper layer on the side of the first surface and the lower layer on the side of the second surface include fusion-bonded fiber of the same type. 16. Three-dimensional sheet of paragraphs. 2, 3, 4 or 8, in which: the first fiber has a larger diameter ratio than the second fiber; and the top layer on the side of the first surface is made only from the first fiber. 17. Three-dimensional sheet of paragraphs. 2, 3, 4 or 8, in which: the first fiber has a larger diameter ratio than the second fiber; and the second fiber is contained only in the lower layer on the side of the second surface. 18. Three-dimensional sheet of PP. 1, 3, 4, or 8, in which the second fiber is a short fiber. 19. Three-dimensional sheet of PP. 1, 3, 4 or 8, in which: the first fiber has a larger diameter ratio than the second fiber; and the second fiber is a fusionable fiber consisting of a core and a shell, comprising a low-melting component as a shell resin and a refractory component as a core resin. 20. The three-dimensional sheet according to claim 19, in which the shell resin in the second fiber is a polyethylene resin. 21. The three-dimensional sheet according to claim 19, in which the shell resin in the second fiber is a low-melting polyester or low-melting polypropylene. 22. Three-dimensional sheet of paragraphs. 1, 3, 4 or 8, in which: the first fibrous layer has a multilayer structure comprising an upper layer on the side of the first surface and a lower layer on the side of the second surface; and P1 is less than P2, where P1 is the average number of S1 connected by fusing points on the fiber with respect to the fiber density in the upper layer on the first surface side and the number of S2 connected by fusing points on the fiber in relation to the fiber density in the lower layer on the side the second surface, and P2 is the number of fusion-connected points on the fiber with respect to the fiber density on the first surface side of the second fibrous layer. 23. The three-dimensional sheet according to claim 22, in which P1 is preferably 55% or more, more preferably 65% or more with respect to P2. 24. The three-dimensional sheet according to claim 22, in which P1 is preferably 95% or less, more preferably 85% or less with respect to P2. 25. The three-dimensional sheet according to claim 22, in which the value of P1 is preferably 150 points / mm ³ or more, preferably 175 points / mm ³ or more, and preferably 240 points / mm ³ or less, more preferably 215 points / mm ³ or less . 26. The three-dimensional sheet according to claim 22, in which the value of P2, provided that P2 is greater than P1, is preferably 220 points / mm ³ or more, preferably 240 points / mm ³ or more, and preferably 300 points / mm ³ or less, preferably 280 points / mm ³ or less. 27. The three-dimensional sheet according to claim 22, in which the fiber density, which serves as the basis for calculating P1 and P2, is the mass of the nonwoven web per unit of volume, while µg / mm ^{3 is} taken as the unit of fiber density. 28. The three-dimensional sheet according to claim 22, in which: the density of the upper layer fiber on the first surface side means the density of the fiber layer located on the apex side; and the density of the fiber of the lower layer on the side of the second surface means the density of the fiber layer located on the side of the second fibrous layer. 29. The three-dimensional sheet according to claim 22, in which: if the second fibrous layer has a single-layer structure, the fiber density on the side of the first surface of the second fibrous layer means the density of the fiber portion located on the side of the first fibrous layer when the thickness of the second fibrous layer is divided in half, and if the second fibrous layer has a two-layer structure, the fiber density on the side of the first surface of the second fibrous layer means the density of the fiber layer located on the side of the first fibrous layer. 30. The three-dimensional sheet according to claim 22, wherein the number of fusion-connected points on the fiber means the number of fusion-connected points per fiber and is defined in units of “number of points / fiber”. 31. The three-dimensional sheet according to claim 22, wherein, in the first fibrous layer, the number S2 of the fusion-connected points on the fiber with respect to the density of the fiber on the second surface is less than the number S1 of the fusion-connected points on the fiber with respect to the density of the fiber on side of the first surface. 32. The three-dimensional sheet according to claim 22, in which S1 is preferably more than 100%, more preferably 105% or more with respect to S2. 33. The three-dimensional sheet according to claim 22, in which S1 is preferably 300% or less, more preferably 125% or less with respect to S2. 34. Absorbent product using a three-dimensional sheet of PP. 1, 3, 4 or 8. 35. Absorbent product using a three-dimensional sheet of PP. 1, 3, 4 or 8 so that the first fibrous layer is facing the user's skin.

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