RU2791337C1 - Non-woven material, product from non-woven material and absorbent product provided with non-woven material and method of manufacturing the said product from non-woven material - Google Patents

Abstract

FIELD: fabrics.

SUBSTANCE: invention relates to a nonwoven fabric having a first surface and a second surface. The nonwoven fabric contains thermoplastic fibers and includes substantially orthogonal fused portions (C) in which the fibers are thermally fused in a state wherein they cross each other at an angle of 70-90° as bonded portions (P), formed by thermal fusion, wherein the places of fibers crossing are subjected to thermal fusion. The nonwoven fabric contains fine fibers with a fiber diameter of 15 mcm or less. When at least one of the first surface and the second surface in the nonwoven fabric is examined at a magnification of 200 times within observation zones having a size of 500 mcm × 400 mcm, the proportion of fine fibers is 20% or more, and the proportion of substantially orthogonal fused portions is 35% or more, wherein the proportion of substantially orthogonal fused portions is the ratio of the number of portions (C) in which the fibers are fused in a substantially orthogonal state to the number of bonded portions (P) formed by thermal fusion and present in the viewing area.

EFFECT: non-woven fabric containing thermoplastic fibers and including substantially orthogonal fused portions.

20 cl, 3 dwg, 1 tbl

Description

The field of technology to which the invention belongs

[0001]

The present invention relates to a nonwoven fabric, a nonwoven fabric product including the nonwoven fabric, an absorbent product, and a method for making a nonwoven fabric product.

prior art.

[0002]

The nonwoven material is used for sheet members forming absorbent articles such as disposable diapers. As such a nonwoven material, a nonwoven material is known which is formed from thermofusion bonded fibers which are fused to each other at the crossovers of the fibers. For example, the Applicant has previously proposed a nonwoven fabric which is formed from at least two types of mixed fibers, bonded by thermofusion, which are difficult to fuse together, and has regions in which fibers of the same type are fused throughout (Patent Literature 1) .

[0003]

In addition, the Applicant has previously proposed a nonwoven fabric that contains bicomponent fibers joined by thermofusion and consisting of a first polymer component and a second polymer component having a higher melting point than the first polymer component, and includes fused areas of the fibers on which the contacting the fiber portions are fused, and the ratio of the number of portions in which the thermally bonded bicomponent fibers are bonded in parallel to the number of fused fiber portions is a predetermined value (Patent Literature 2).

[0004]

In addition, the Applicant has previously proposed a three-dimensional sheet in which the first and second fibrous layers formed from nonwoven fabric are superimposed and connected, the first fibrous layer protrudes in the direction from the second fibrous layer to form a large number of hollow protrusions, the first fiber and the second the fibers contained in the first fiber layer have a high melting point component and a low melting point component, respectively, and the high melting point component and the low melting point component differ from each other in a diameter ratio (Patent Literature 3).

[0005]

Patent Literature 4 discloses a two-layer composite nonwoven fabric, in which the nonwoven fabric (A) includes short fibers having a fiber length of 38 to 90 mm, and the nonwoven fabric (B) includes short fibers having a fiber length of 3 up to 30 mm. The nonwoven fabric (B) comprises short thermofusion bonded fibers which are formed from a thermoplastic resin including at least a high melting point component and a low melting point component, wherein the thermofusion bonded short fibers are thermofused to each other. another to form points of contact between short fibers. The D4 nonwoven fabric ( Patent Literature 4 ) has a distribution of criss-cross angles at the junctions in which the junctions with a 60°-90° criss-cross angle make up at least 50% of the total number of junctions in the nonwoven fabric (B) .

In D5 and D6 (Patent Literature 5 and 6) discloses a two-layer composite nonwoven fabric which is used for an absorbent article and in which a nonwoven fabric containing long fibers and a nonwoven fabric containing short fibers are bonded to each other. The short fiber nonwoven fabric comprises a thermofusion bonded multicomponent fiber which is formed from a thermoplastic resin including a high melting point component and a low melting point component, wherein the thermofusion bonded multicomponent fibers are thermofused to each other to form contact points between short fibers. Double layer composite nonwoven according to D5 and D6 (Patent Literature 5 and 6) has a distribution of cross angles at the contact points, in which the proportion of contact points with a cross angle of 60°-90°, of the total number of contact points in a nonwoven material containing short fibers, is a predetermined value.

D7 ( Patent Literature 7 ) discloses a unidirectional fiber nonwoven fabric in which the molded continuous fibers are arranged in a single direction, or a multilayer nonwoven fabric in which two unidirectional fiber nonwoven fabrics are stacked on top of each other so that the direction continuous fibers of one unidirectional nonwoven material orthogonally to the direction of the continuous fibers of another nonwoven unidirectional fiber material. D7 ( Patent Literature 7 ) discloses that the continuous fiber diameter is 3-20 µm, the bulk density of the unidirectional nonwoven fabric is 0.1 g/cm ³ or more, and the areal density of the unidirectional fiber nonwoven fabric is 5 -40 g/cm ² .

Link List

Patent Literature

[0006]

Patent Literature 1: Japanese Patent Application Laid-Open No. H09-279467

Patent Literature 2: International Publication No. 2011/046065

Patent Literature 3: Japanese Patent Application Laid-Open No. 2017-024411

Patent Literature 4: Japanese Patent Application Laid-Open No. H10-273884

Patent Literature 5: Japanese Patent Application Laid-Open No. H09-021055

Patent Literature 6: Japanese Patent Application Laid-Open No. H09-117470

Patent Literature 7: Japanese Patent Application Laid-Open No. 2006-043998

The essence of the invention

[0007]

In accordance with the present invention, there is provided a nonwoven material having a first surface and a second surface located on the side opposite to the first surface.

The nonwoven fabric preferably contains thermoplastic fibers and includes substantially orthogonal fused portions, and in which the fibers are thermally fused in a state in which they cross each other at an angle of 70°-90° as bonded portions formed by thermofusion, in which the places of crossing of the fibers are subjected to thermal fusion.

The nonwoven material preferably contains fine fibers having a fiber diameter of 15 µm or less.

In the nonwoven fabric, when at least one of the first surface and the second surface is examined at a magnification of 200 times in a viewing zone having a size of 500 µm × 400 µm, the proportion of fine fibers is preferably 20% or more and the proportion of substantially orthogonal fused portions, preferably 35% or more, wherein the proportion of substantially orthogonal fused portions is the ratio of the number of substantially orthogonal fused portions to the number of bonded portions formed by thermal fusion present in a given observation zone.

[0008]

In accordance with the present invention, there is provided a nonwoven product including the nonwoven material.

The first surface preferably has a higher proportion of substantially orthogonal fused portions than the second surface.

The first surface is preferably located such that it forms the surface of the nonwoven article.

[0009]

In accordance with the present invention, an absorbent article is provided that includes this nonwoven material as a constituent element.

[0010]

In accordance with the present invention, there is provided a method for manufacturing a nonwoven article, including a nonwoven fabric having a first surface and a second surface located on a side opposite the first surface.

The non-woven material preferably contains thermoplastic fibers and includes substantially orthogonal fused portions and in which the fibers are thermally fused in a state in which they cross each other as thermally bonded portions in which the crossovers of the fibers are thermally fused.

The nonwoven material preferably contains fine fibers having a fiber diameter of 15 µm or less.

In the nonwoven fabric, when at least one of the first surface and the second surface is examined at a magnification of 200 times in a viewing zone having a size of 500 µm × 400 µm, the proportion of fine fibers is preferably 20% or more and the proportion of substantially orthogonal fused portions, preferably 35% or more, wherein the proportion of substantially orthogonal fused portions is the ratio of the number of substantially orthogonal fused portions to the number of bonded portions formed by thermal fusion present in a given observation zone.

The method for manufacturing a nonwoven article preferably includes the step of overlapping the nonwoven with another constituent element such that a surface having a lower proportion of substantially orthogonal fused portions faces the other constituent element.

Other features of the present invention will be apparent from the claims and the description below.

Brief description of the drawings

[0011]

[Figure 1] Figure 1 is an example of an observed image obtained by examining one surface of the nonwoven fabric of the present invention using a scanning electron microscope.

[Figure 2] Figure 2 is a schematic view showing substantially orthogonal fused portions, in accordance with an embodiment of the present invention.

[FIG. 3] FIG. 3 is a schematic representation of a nonwoven fabric including parallel fused portions, which image corresponds to FIG.

Detailed Description of the Embodiment

[0012]

The use of a fiber having a small fiber diameter for a nonwoven fabric is effective in terms of improving the texture and improving the smoothness to the hand. However, such a nonwoven fabric often has a high extensibility, and width shrinkage may occur in the stretched state, at which the width of the nonwoven fabric may decrease. In particular, when the width of the nonwoven material decreases due to shrinkage due to the tensile force applied to the nonwoven material during its movement in the manufacture of a nonwoven product, the specified width may not be obtained, and defective products may be formed. Patent Literature 1-3 do not disclose technical solutions for preventing width shrinkage of the nonwoven fabric.

[0013]

Accordingly, it is an object of the present invention to provide a nonwoven fabric which contains fibers having a small fiber diameter and in which width shrinkage is prevented, a nonwoven fabric article, and an absorbent article including the nonwoven fabric, and a method for manufacturing the article. from non-woven material.

[0014]

The present invention will be described below based on the preferred embodiment with reference to the drawings.

The nonwoven material of an embodiment comprises thermoplastic fibers and includes bonded sections P formed by thermofusion, in which the crossovers of the fibers are thermally melted. Such a bonded portion P formed by thermofusion is formed at a portion in which the thermoplastic fibers are in contact with each other, and such portions are three-dimensionally distributed in the nonwoven fabric.

The nonwoven fabric of an embodiment includes a substantially orthogonal fused portion C as a bonded portion P formed by thermofusion. The substantially orthogonal fused portion C is a portion in which the thermoplastic fibers are fused in a substantially orthogonal state at the intersections of the thermoplastic fibers. "Substantially orthogonal" means a state in which the fibers cross at an angle in the range of 70° to 90°. A method for measuring the fiber crossing angle in the thermofusion bonded portion P will be described below.

[0015]

1 shows an image of one surface of the nonwoven fabric of the embodiment taken with an electron microscope (inspection magnification: 200 times) by photographing according to the <Method for determining the proportion of substantially orthogonal fused portions> to be described below.

As shown in FIG. 1, the nonwoven fabric of the embodiment includes a plurality of bonded regions P formed by thermofusion, in which the crossing points of thermoplastic fibers contained as constituent fibers are thermally bonded, and includes substantially orthogonal fused regions C, as connected sections P formed by thermofusion. In Fig. 1, portions E in which the fibers are fused in a parallel state are formed as bonded portions P formed by thermofusion in which the fibers are fused in a non-orthogonal state. The "non-orthogonal state" encompasses a state in which the fibers are arranged in parallel and a state in which the fibers are arranged substantially in parallel. In particular, the fiber crossing angle in the portion E where the fibers are fused in a parallel state is 0° or more and less than 70°. In figure 1, the sections indicated by the reference positions P1-P7 are connected sections formed by thermofusion, the sections indicated by the reference positions C are essentially orthogonal fused sections, and the sections indicated by the reference positions E are sections in which the fibers are fused in a parallel state.

[0016]

The nonwoven fabric has two surfaces, namely a first surface and a second surface, formed in a direction orthogonal to the thickness direction of the nonwoven fabric, wherein the first and second surfaces are spaced apart in the thickness direction. When at least one of the first surface and the second surface of the nonwoven fabric of the embodiment is examined at a magnification of 200 times in a viewing area having a size of 500 µm x 400 µm (hereinafter simply referred to as "viewing area"), the ratio of the number of areas C, in which the fibers are fused in a substantially orthogonal state, to the number of connected areas P formed by thermofusion and present in the observation zone is 35% or more. This ratio is referred to herein as the "substantially orthogonal fusion ratio". The proportion of substantially orthogonal fused portions is determined by the method below.

[0017]

<Method for determining the proportion of substantially orthogonal fused portions>

An area of 10 mm × 30 mm in plan view is cut out along the entire length of the nonwoven fabric to be measured in the thickness direction using a sharp razor, and this area is used as a measurement sample. One of the two surfaces of the measurement sample is photographed at a magnification of 200 times in the zone (observation zone) with dimensions of 500 μm × 400 μm using a scanning electron microscope (SEM, trade name: JCM-6000, manufactured by JEOL Ltd., corresponding to all scanning electron microscopes (SEM) in the description). When photographing with the SEM, the focus is on the fiber located on top of the measurement sample to be photographed. One measurement sample is photographed at five different locations, and a total of five SEM images are obtained. Thereafter, fibers that are in focus are selected from each of the SEM images, and the number of bonded thermofusion sites P in which these fibers are thermally melted from these fibers is counted. A " focused fiber" is a fiber whose outline is not blurred in the area of interest. Wherein, any of the smaller angles relative to the vertical of the four angles formed by the selected fibers in the thermofusion bonded portion P is measured as the fiber crossing angle, and based on whether the crossing angle is in the range of 70° to 90° described above, determine whether the bonded section P formed by thermofusion is a section C in which the fibers are fused in a substantially orthogonal state. Thereafter, the number of sections C, which are formed by fusion of fibers crossing substantially orthogonally, in which the fibers are fused in a substantially orthogonal state, are counted from the joined sections P formed by thermofusion. The number of connected sections P formed by thermofusion and sections C in which the fibers are fused in a substantially orthogonal state are counted in each of the SEM images, and the ratio of the number of sections C in which the fibers are fused in a substantially orthogonal state to the number of connected of P sites formed by thermofusion, that is, expressed as a percentage of the ratio "the number of sections C in which the fibers are fused in a substantially orthogonal state/the number of connected sections P formed by thermofusion". This proportion is obtained for each of the SEM images, and the average value of these proportions is determined as the proportion of substantially orthogonal fused areas, on one surface of the nonwoven material.

[0018]

The method for counting the bonded sections P formed by thermofusion and the sections C in which the fibers are fused in a substantially orthogonal state and which are present in each observation zone will be described in detail with reference to Figures 1 and 2. First, a fiber is selected that is in focus and at the top of the SEM image and a fiber that has been thermally fused to the fiber in focus. In Fig. 1, fiber a1 is the top fiber, and the fiber whose end in the direction of the fiber diameter is not smeared in the observation zone with a size of 500 μm x 400 μm is selected together with fiber a1 as the "fiber in focus" . After that, the connected sections P formed by thermofusion are selected and counted, in which the selected fibers are subjected to thermofusion. In FIG. 1, the thermofusion bonded portion indicated by P2 is omitted because the thermofusion bonded fiber in the portion indicated by P2 is not a "fiber in focus". That is, in Fig. 1, six connected portions P formed by thermofusion are located on top. Thereafter, any of the smaller angles relative to the vertical of the four angles formed by the selected fibers F in each of the bonded thermofusion portions P is measured as the fiber crossing angle Ɵ F (see FIG. 2). The bonded portion P formed by thermofusion, which has a crossing angle Ɵ (not shown in FIG. 1) of 70° or more, is defined as the portion C in which the fibers are fused in a substantially orthogonal state, and the bonded portion P formed by thermofusion, which has a crossing angle Ɵ of less than 70° is defined as a portion E in which the fibers are fused in a parallel state. 1, the three bonded thermofusion portions P1, P4 and P7 of the five thermofusion bonded portions P are the C portions in which the fibers are fused in a substantially orthogonal state, and the remaining two bonded portions P3 and P6 formed thermofusion, represent areas E in which the fibers are fused in a parallel state. The same selection and determination is made for all "fibers in focus" on the same SEM image. Therefore, the proportion of substantially orthogonal fused portions is 60% in FIG. The surface of the nonwoven material is not microscopically flat, but uneven. Accordingly, the "upper fiber" in the viewing area is located within an interval from the side of the top surface to the location inside, located at a distance of approximately 100 μm and defined in the direction of the thickness of the nonwoven fabric, and exposed to the side of the top surface. The "fiber in focus" in the area of interest is located within an interval from the side of the top surface to the inside, located at a distance of approximately 100 μm, in thickness direction.

[0019]

The nonwoven fabric of the embodiment comprises fibers having a fiber diameter of 15 µm or less (hereinafter also referred to as "fine fiber"). Fine fibers are present on the first surface or second surface of the nonwoven material of the embodiment, but fine fibers may be present within the nonwoven material.

The presence of fine fibers on the first surface or the second surface can be confirmed by the presence or absence of fine fibers observed in the observation area according to the <Fine Fiber Fraction Method> to be described below.

[0020]

In the nonwoven material of an embodiment, at least one of the first surface and the second surface has a proportion of substantially orthogonal fused portions of 35% or more and a proportion of fine fibers that are present in the viewing area of 20% or more. The proportion of fine fibers shows the proportion of fine fibers present in the area of interest. Such an observation area is identical to the observation area in the above <Method for determining the proportion of substantially orthogonal fused portions>.

For reasons related to further improving the smoothness to the touch, the proportion of fine fibers on at least one of the first surface and the second surface is preferably 25% or more, and more preferably 30% or more.

The proportion of fine fibers on at least one of the first surface and the second surface is actually 100% or less.

The proportion of fine fibers is obtained by the following method based on the inspection of the surface. When the presence of fine fibers can be confirmed by the surface inspection described below, that is, when fine fibers are present on at least one of the first surface and the second surface of the nonwoven fabric, the texture specific to fine fibers and smoothness to the touch can actually be more reliably secured. when touched by hand.

[0021]

<Method for determining the proportion of thin fibers>

The measurement sample is cut out in the same manner as in the above <Method for determining the proportion of substantially orthogonal fused portions>, and SEM images corresponding to observation areas on any surface of one measurement sample (5 images for one surface) are obtained. The proportion of thin fibers is determined for each of the obtained SEM images by the following method. First, the "fibers in focus" are selected from the SEM image. Thereafter, for each of the fibers in focus, in an arbitrary portion other than the bonded portions P formed by thermofusion, a line orthogonal to the longitudinal direction of the fiber is drawn, and the fiber diameter value determined along this line is measured as the fiber diameter. Such a measurement is made at that location of the fiber in focus at which the line showing the contour of the fiber is orthogonal to the line showing the diameter value, that is, to the line orthogonal to the longitudinal direction. Thereafter, the number of fibers having a fiber diameter of 15 μm or less is counted as the number of fine fibers, and the ratio of the number of fine fibers to the number of fibers in focus in the SEM image, that is, the percentage (%), is obtained as "number of fine fibers/number of fibers in focus". Such a proportion is obtained for each of a total of five SEM images obtained for the measurement sample, and the average value of the obtained proportions is defined as the "fine fiber proportion". The "fine fiber ratio" is determined for each of the two surfaces of the nonwoven fabric.

[0022]

In the nonwoven fabric of an embodiment, the proportion of fine fibers on at least one of the first surface and the second surface is 20% or more, and the proportion of substantially orthogonal fused portions is 35%.

In the nonwoven fabric of an embodiment, the proportion of fine fibers on both of the first surface and the second surface may be 20% or more, and the proportion of substantially orthogonal fused portions may be 35%.

[0023]

Because the nonwoven fabric has a fine fiber ratio on at least one of the first surface and the second surface of 20% or more, the nonwoven fabric is smooth to the touch and has a good texture. In addition, since the nonwoven fabric has a proportion of substantially orthogonal fused portions on at least one surface of 35% or more, even when it contains fine fibers, width shrinkage hardly occurs when the nonwoven fabric is stretched. Since the proportion of substantially orthogonal fused regions is a relative indication of the presence of regions in which the fibers are fused in an orthogonal state, the constituent fibers of the nonwoven material of an embodiment are considered to be dispersedly oriented in a plurality of directions. Even when a worker tries to stretch the nonwoven fabric in one direction, the nonwoven fabric hardly stretches in that direction.

This can be easily understood from the comparison between FIGS. 2 and 3. When the orientation of the constituent fibers is as shown in FIG. in a substantially orthogonal state, since the fibers running in the same direction (Y direction in FIG. 3) are fused in the portion E in which the fibers are fused in a parallel state, it is difficult to limit the stretching of fibers running in the direction (X direction in FIG. 3) different from the given one and the same direction. On the other hand, since the orientation of the fibers F in the multi-direction nonwoven is different, as shown in FIG. 2, the fibers F1 running in a direction (Y direction in FIG. 2) are difficult to stretch, and since the stretch of the fibers F running in a given one direction is limited between the portions C in which the fibers are fused in a substantially orthogonal state (see FIG. 2), the entire nonwoven fabric is considered to be difficult to stretch in a given direction. By this, width shrinkage caused by stretching can be effectively prevented.

Such an effect is useful during the manufacture of a nonwoven article such as an absorbent article. For example, the nonwoven fabric is generally moved during manufacture of the nonwoven fabric article in a state in which a tensile force is applied in the moving direction (machine direction), and the nonwoven fabric may be in a state in which it is stretched in the moving direction. It can be stated that the greater the maximum relative elongation of the nonwoven material in the direction of movement in such a state, the greater the extensibility in the direction of movement with respect to the tensile force applied to the nonwoven material. It is also apparent that the more the nonwoven material is stretched in the direction of travel, the narrower the width of the nonwoven material becomes. Accordingly, the maximum elongation of the nonwoven fabric in the moving direction (machine direction) can be used as an index of shrinkage in width, a decrease in the maximum elongation in the driving direction leads to a decrease in width shrinkage, and the production efficiency of the nonwoven fabric can be improved.

Since the nonwoven fabric of the embodiment is difficult to be stretched in the moving direction and the maximum elongation of the nonwoven fabric in the moving direction is reduced, that is, almost no width shrinkage occurs, even when a stretching force is applied in the moving direction, almost no dimensional problems due to shrinkage in width. In addition, the nonwoven fabric of the embodiment can be moved at a high speed at which a tensile force is likely to be applied, and therefore, by using this nonwoven fabric, the manufacturing efficiency of the nonwoven fabric product can be improved.

[0024]

Generally, when thin fibers are present, the number of fibers per unit basis weight naturally increases compared to thick fibers. Therefore, since the contact area between the fibers will often be large, regions where the fibers are fused in a parallel state are easily formed, as shown in FIG. However, even when the nonwoven material of the embodiment contains fine fibers, for example, even when the proportion of fine fibers on at least one of the two surfaces is high and is 20% or more, fiber orientations F are easily "distributed" in multiple directions, because the proportion substantially orthogonal fused portions is 35% or more, and the effect of limiting the stretching of the fibers is significant because the relative index of the presence of portions C in which the fibers are fused in a substantially orthogonal state, which is the proportion of these portions of the bonded portions P formed by thermofusion , is sufficient, and as a result, the width shrinkage reduction effect is also significant.

[0025]

For reasons related to further reduction in width shrinkage, the proportion of substantially orthogonal fused portions is preferably 50% or more, and more preferably 52% or more.

In addition, for reasons related to the actual structure of the nonwoven material, the proportion of substantially orthogonal fused portions is preferably 80% or less, and more preferably 70% or less.

In addition, the proportion of substantially orthogonal fused portions is preferably 50% to 80%, and more preferably 52% to 70%.

[0026]

For reasons related to the further reduction of width shrinkage, the total number of sections C in which the fibers are fused in a substantially orthogonal state and which are present in the five viewing zones is preferably 15 or more, and more preferably 20 or more.

In addition, for reasons related to the actual structure of the nonwoven fabric, the total number of areas C in which the fibers are fused in a substantially orthogonal state and which are in the five viewing zones is preferably 50 or less, and more preferably 40 or less.

In addition, the total number of regions C in which the fibers are fused in a substantially orthogonal state and which are present in the five viewing zones is preferably 15 to 50, and more preferably 20 to 40.

The total number of sections C in which fibers are fused in a substantially orthogonal state and which are present in the five observation zones is obtained by the same method as the above <Method for determining the proportion of substantially orthogonal fused sections>, and this number is the total number of sections C, in which the fibers are fused in a substantially orthogonal state, in a total of five SEM images.

[0027]

For reasons related to the additional reduction in width shrinkage, the proportion of substantially orthogonal fused portions is preferably within the above range on the upper side of the nonwoven fabric. On the other hand, for reasons of greater softness of the nonwoven fabric, the proportion of substantially orthogonal fused portions is preferably smaller at the location inside with respect to the top side of the nonwoven fabric than on the side of the nonwoven fabric top in the thickness direction of the nonwoven fabric, and more preferably is less than 50% at the location located inside with respect to the upper side of the nonwoven material.

For reasons related to further reduction of width shrinkage, the total number of regions C in which the fibers are fused in a substantially orthogonal state and which are present in the five viewing zones is preferably within the above range on the upper side of the nonwoven fabric. On the other hand, for reasons of greater softness of the nonwoven fabric, the total number of regions C in which the fibers are fused in a substantially orthogonal state, which are present in the five viewing zones, is preferably less in the location located inside with respect to the upper side of the nonwoven fabric. material than on the side of the nonwoven fabric upper in the thickness direction of the nonwoven fabric, and more preferably is less than 15 at the location inside with respect to the top side of the nonwoven fabric.

The proportion of substantially orthogonal fused portions, and the total number of portions C in which the fibers are fused in a substantially orthogonal state and which are present in the five observation zones and located inward with respect to the upper side of the nonwoven fabric, are determined according to the same method as the above <Method determining the proportion of substantially orthogonal fused areas>, with the exception of viewing the section - formed by cutting the non-woven material at a place corresponding to half the thickness of the non-woven material - as a measurement sample to be photographed.

[0028]

When the proportion of substantially orthogonal fused portions in the nonwoven fabric on either of the first surface and the second surface is equal to or greater than the lower limit value presented above, an effect of reducing width shrinkage can be obtained. For example, when the proportion of substantially orthogonal fused portions, as described above, is determined for each of two surfaces of the nonwoven fabric, the proportion for any one surface may be equal to or greater than the lower limit value.

[0029]

In the nonwoven fabric of an embodiment, the proportion of substantially orthogonal fused regions on the first surface is preferably different from the proportion of substantially orthogonal fused regions on the second surface. In this case, for example, a surface having a higher proportion of substantially orthogonal fused portions is defined as the first surface.

When the proportion of substantially orthogonal fused portions on the first surface is different from the proportion of substantially orthogonal fusion portions, on the second surface, either of the first surface and the second surface preferably corresponds to the preferred configuration and range of values of the proportion of substantially orthogonal fused portions, and the total number of portions C , in which the fibers are fused in a substantially orthogonal state and which are present in the five viewing zones described above.

[0030]

For reasons related to the manufacture of nonwoven material in practice, the basis weight of the nonwoven material is preferably 5 g/m ² or more, and more preferably 8 g/m ² or more.

For reasons related to the cost of the nonwoven material, the basis weight of the nonwoven material is preferably 30 g/m ² or less, and more preferably 26 g/m ² or less.

In addition, the basis weight of the nonwoven fabric is preferably 5 g/m ² to 30 g/m ² , and more preferably 8 g/m ² to 26 g/m ² .

[0031]

For reasons related to the diameter of the fibers used in the practice of manufacturing the nonwoven fabric, the average diameter of the fibers constituting the fibers of the nonwoven fabric is preferably 5 µm or more, and more preferably 8 µm or more.

For reasons of further improving smoothness, the average diameter of the fibers constituting the fibers of the nonwoven fabric is preferably 30 µm or less, and more preferably 20 µm or less.

In addition, the average diameter of the fibers constituting the fibers of the nonwoven fabric is preferably 5 µm to 30 µm, and more preferably 8 µm to 20 µm.

The nonwoven fabric may be formed from a variety of fiber types having different fiber diameters, but is preferably formed from constituent fibers having a fiber diameter of 15 µm or less, in the same manner as above, and more preferably formed from constituent fibers, having a fiber diameter of 13 µm or less. When a nonwoven material contains multiple types of fibers having different fiber diameters, the "average fiber diameter" is the average of the diameters of the fibers constituting the fibers of the entire nonwoven material. The average fiber diameter is obtained by the following method. When different fibers are mixed in a nonwoven fabric, all fibers are considered to influence the fusing structure, and therefore an average value for the entire nonwoven fabric should be obtained.

[0032]

The diameters of the fibers constituting the fibers of the nonwoven material are obtained by the following method.

The SEM image of the nonwoven fabric obtained in the above <Fine Fiber Fraction Method> is used. On the SEM image, 10 "fibers in focus" are randomly selected as described above. Thereafter, for each of these ten fibers, the fiber diameter described above is measured. Thereafter, the arithmetic mean of the fiber diameters representing these ten fibers is obtained for each of a total of five SEM images obtained from the measurement sample. This arithmetic mean is obtained for each of the two surfaces of the nonwoven material, and the mean of these arithmetic means is determined as the mean fiber diameter.

[0033]

For reasons related to obtaining good softness and texture of the nonwoven fabric, the maximum elongation of the nonwoven fabric of the embodiment is preferably 20% or more, and more preferably 25% or more.

For reasons related to further reduction of width shrinkage during high-speed movement, the maximum elongation is preferably 60% or less, and more preferably 55% or less.

In addition, the maximum elongation is preferably 20% to 60%, and more preferably 25% to 55%.

The maximum elongation is determined by the method below.

[0034]

<Method for determining maximum elongation>

An area measuring 50 mm x 200 mm is cut from the non-woven material to be measured using a sharp razor and used as a measurement sample. In this case, the measurement sample is cut so that the longitudinal direction of the measurement sample corresponds to the orientation directions of the fibers in the nonwoven material. Prepare four samples for measurements.

The fiber orientation direction was confirmed by examining one surface of the nonwoven fabric using a JCM-6000 scanning electron microscope (manufactured by JEOL Ltd.). Prior to such inspection, the nonwoven material is pre-positioned in the manner recommended in the manual for the use of the scanning electron microscope. The non-woven material is examined with a scanning electron microscope at 50 times magnification, and a square is drawn having one side with a length of 500 μm and a diagonal intersection point at the center of the screen in the viewing field. The square is formed so that the sides of the square are parallel to the longitudinal direction or the transverse direction of the nonwoven fabric. Thereafter, the number of fibers extending from one of the two sides of the square on the screen to the other side is counted, the two sides being parallel to each other, extending in the longitudinal direction of the nonwoven fabric and facing each other. This number of fibers is referred to as the "number of i fibers". In the same manner as described above, the number of fibers extending from one of the two sides to the other side is counted, with these two sides parallel to the transverse direction of the nonwoven material and facing each other. This number of fibers is referred to as the "number ii fibers". The fiber orientation on the side having the larger number of fibers of the number of fibers i and the number of fibers ii is defined as the orientation direction of the fibers in the nonwoven fabric. For example, when the number i of fibers extending between two sides parallel to the longitudinal direction of the nonwoven fabric is large, it can be determined that the orientation direction of the fibers in the nonwoven fabric coincides with the transverse direction of the nonwoven fabric. In this case, the measurement sample is cut so that the longitudinal direction of the measurement sample coincides with the transverse direction of the nonwoven material.

[0035]

Thereafter, in a state in which the orientation direction of the fibers in the measurement specimen, that is, the longitudinal direction of the measurement specimen, is aligned with the direction of the tensile force, both ends of the measurement specimen are attached to the clamps of the tensile tester (Model name: “AUTOGRAPH AG- X”, is manufactured by SHIMADZU Corporation and corresponds to all tensile testers in the description). The distance between the clamps is 150 mm. The tensile force (tensile load) applied to the measurement specimen is measured by stretching the measurement specimen fixed between the clamps at a speed of 300 mm/min, and the elongation at the maximum tensile force is obtained. "Elongation" is the ratio (%) of the length after stretching to the original length before stretching. For example, an elongation of 100% means that the sample is stretched to a length that is twice the original length. The above elongation is determined for each sample for measurement, and the average value is taken as the maximum relative elongation.

[0036]

When the position of the vector direction of orientation of the fibers is not clear from the above inspection, the maximum elongation is obtained by the method below. First, a measurement sample having a longitudinal direction coinciding with the longitudinal direction of the nonwoven fabric to be measured, and a measurement sample having a longitudinal direction coinciding with the transverse direction of the nonwoven fabric to be measured are cut out. The tensile test is performed on these two types of measurement specimens, and the higher tensile strength value is determined as the maximum elongation. This is because the tear resistance under a tensile load acting in the fiber orientation direction is greater than the tear resistance under a tensile load acting in a direction other than the fiber orientation, as is commonly known.

When the nonwoven material to be measured is included in a nonwoven product such as an absorbent product, a measurement sample having a longitudinal direction coinciding with the longitudinal direction of the article and a measurement sample having a longitudinal direction coinciding with the transverse direction are cut out. products.

In addition, when the above dimensions cannot be obtained by cutting the measurement sample, the measurement sample having a length in the transverse direction of 50 mm and a length in the longitudinal direction in increments of 50 mm (for example, 50 mm × 150 mm or 50 mm × 100 mm). In this case, the distance between the jaws of the tensile tester is set to be 50 mm less than the length of the test piece, measured in the longitudinal direction. As described above, even when the length of the measurement specimen measured in the longitudinal direction is changed, the maximum elongation determination result can be compared as such.

[0037]

The nonwoven fabric of an embodiment includes primarily thermoplastic fibers. The proportion of contained thermoplastic fibers from all constituent fibers of the nonwoven material according to the embodiment is at least 50% of the mass. or more, preferably 90% of the mass. or more and may be 100% of the mass.

[0038]

Examples of constituent resins/polymers (thermoplastic resins/polymers) of thermoplastic fiber include polyolefin such as polyethylene (PE) or polypropylene (PP), polyester such as polyethylene terephthalate (PET), polyamide such as nylon 6 or nylon 66, polyacrylic acid , polymethacrylic acid alkyl ester, polyvinyl chloride, polyvinylidene chloride, and these resins/polymers may be used alone or in combination of two or more.

[0039]

The synthetic fiber, including the thermoplastic fiber used in the nonwoven fabric of the embodiment, may be a single-component fiber formed from one kind of synthetic resin or a mixed polymer obtained by mixing synthetic resins of two or more kinds, or may be a multi-component fiber. The multi-component fiber described above is a synthetic fiber obtained by combining two or more synthetic resins having different components by a spinneret and simultaneously spinning, and has a structure in which a plurality of components are respectively continuous in the fiber length direction and bonded to each other in one fiber. The type of multicomponent fiber includes, for example, a core-clad fiber having a core-clad structure including a core and cladding, or a side-by-side fiber.

[0040]

The thermoplastic fiber preferably contains polyethylene (PE) as a resin constituent, more preferably contains PE at least on the surface, and even more preferably consists of PE.

For example, in the case of having a core-sheath fiber as a thermoplastic fiber, the core resin component is PET and the sheath resin component is preferably PE.

[0041]

A preferred example of a thermoplastic fiber is a thermoplastic fiber consisting of a bicomponent core-sheath fiber in which the core forming component is one or more polymers selected from the group consisting of PET and PP and the sheath forming component is one or more polymers selected from the group consisting of PE. Since the fusion between the fibers occurs only in the cladding region and the core remains unfused, in the core-clad bicomponent fiber, the core performs the function of preventing the fiber from stretching. Accordingly, a thermoplastic fiber consisting of a core-sheath bicomponent fiber is preferred for reasons of preventing fiber stretching and reducing width shrinkage.

[0042]

In addition, the thermoplastic fiber is preferably a short fiber. The short fiber is a fiber having a fiber length of less than 80 mm. It is preferable to form a web using short fibers due to the fact that different orientation of the fibers is easily provided, and substantially orthogonal fused regions are easily formed, as shown in Fig.2. In such a case, the nonwoven fabric of the embodiment does not include a spunbonded nonwoven fabric.

[0043]

Since the likelihood of contact between thermoplastic fibers is reduced and substantially orthogonal fused regions are more easily formed than regions in which the fibers are fused in a parallel state, by adding non-thermofusion bonded fibers, the nonwoven fabric of the embodiment may contain fibers other than the thermoplastic fiber. Examples of such other fibers include natural fibers such as cellulose and cotton and cellulose fibers such as rayon fibers, lyocell fibers and Tencel fibers, and one of these fibers may be used alone, or two or more of them may be used in the form of a mixture.

In particular, it is preferable to use a mixture of a PET/PE bicomponent core-sheath fiber and a cotton fiber.

[0044]

For the above reasons, the proportion of other fibers in all constituent fibers of the nonwoven material is preferably 0.5% of the mass. or more and more preferably 1% of the mass. or more.

For reasons related to maintaining tear resistance, this proportion is preferably 20 wt%. or less and more preferably 10% of the mass. or less.

In addition, this proportion is preferably from 0.5% of the mass. up to 20% wt. and more preferably from 1% of the mass. up to 10% wt.

[0045]

The nonwoven material of the embodiment is used for a nonwoven product. The nonwoven product is an article made from a nonwoven material or an article including a nonwoven material as a constituent member. Examples of nonwoven articles include absorbent articles such as disposable diapers or panty liners, heating aids such as eye masks, surgical gowns and masks, cleaning sheets and wipe sheets. The "absorbent article" described above broadly encompasses articles that are used to absorb bodily fluids (urine, loose stools, menstrual blood, sweat, and the like) discharged from the human body, and include, for example, disposable diapers , sanitary pads, sanitary pants, urological pads.

[0046]

An absorbent article typically includes a liquid-pervious topsheet located relatively close to the wearer's skin, a liquid-impermeable or minimally liquid-permeable or water-repellent backsheet located relatively far from the wearer's skin, and a liquid-retaining absorbent member. located between the given two sheets. The absorbent article may include an outer cover forming its outer surface.

When the nonwoven material of the embodiment is used for an absorbent article, the absorbent article includes the nonwoven material as a constituent member.

[0047]

The nonwoven material of an embodiment is formed from one layer of nonwoven material, but may be in a state in which it is superimposed on another sheet material, such as another nonwoven material or film, and connected to this other sheet material when it is used as a constituent element. absorbent product.

[0048]

For reasons of more reliable smoothness to the touch, when using the nonwoven fabric of the embodiment as a constituent element of the nonwoven fabric product, the first surface of the nonwoven fabric is preferably positioned to form the surface of the nonwoven fabric product.

For example, in an absorbent article using the nonwoven material of the embodiment, the nonwoven material is preferably used as a sheet forming the outer surface or the inner surface of the absorbent article. In particular, the nonwoven fabric of the embodiment is preferably provided as one or both of the top sheet and the back sheet, and the nonwoven fabric is more preferably provided as the back sheet.

The nonwoven fabric of an embodiment is preferably positioned in the absorbent article such that the surface having a higher proportion of substantially orthogonal fused portions faces the outer surface of the absorbent article. In particular, when the nonwoven fabric of the embodiment is used as the topsheet, the surface having a higher proportion of substantially orthogonal fused portions is positioned to form a skin-facing surface. In addition, when the nonwoven fabric of the embodiment is used as the backsheet, the surface having a higher proportion of substantially orthogonal fused portions is positioned to form a non-skin facing surface. For reasons of better leakage protection, such a backsheet is preferably formed from a laminated sheet consisting of a minimally liquid permeable sheet and this nonwoven material.

The skin-facing surface is the surface facing the skin of the wearer of the absorbent article, and the non-skin-facing surface is the surface facing away from the wearer's skin, or the surface facing the garment such as a pant.

[0049]

For reasons related to easily providing good softness and texture to the nonwoven fabric, the nonwoven fabric of the embodiment is preferably placed in the absorbent article such that the surface having a higher proportion of substantially orthogonal fused portions faces the interior of the absorbent article. In particular, when the nonwoven material of the embodiment is used as the topsheet, the surface having a higher proportion of substantially orthogonal fused portions is positioned to form a non-skin facing surface of the absorbent article. Further, when the nonwoven material of the embodiment is used as a backsheet, a surface having a higher proportion of substantially orthogonal fused portions is positioned to form a skin-facing surface of the absorbent article.

[0050]

When the nonwoven material of an embodiment is included in a nonwoven product, such as a commercially available absorbent product, the adhesive connecting the constituent elements of the nonwoven product is cured using cold spray or liquid nitrogen, the respective elements are carefully separated to separate nonwoven fabric. When the nonwoven material to be measured is separated from the nonwoven product, such a separation method is common to other measurements in the specification.

[0051]

The manufacturing method of the nonwoven fabric of the above embodiment will be described below. The manufacturing method includes a heat treatment process consisting in heating a fibrous web containing thermoplastic fibers. The heat treatment process is a process of fusing the criss-crossings of the constituent fibers of the fibrous web to form a thermally fused bonded portion and hence form a nonwoven fabric.

[0052]

A fibrous web is generally made by opening virgin fibers such as thermoplastic fibers with an opener and converting the opened raw fiber into a web with a card. The fibrous web is a sheet in a state prior to being converted to a nonwoven fabric, and in the fibrous web, the fibers are not thermally fused. As starting fibers, ie the constituent fibers of the fibrous web, preferably the same fibers as the constituent fibers of the nonwoven fabric described above are used. In addition, the basis weight of the fibrous web is preferably adjusted to values within the range of basis weight of the nonwoven fabric described above.

The fibrous web may be formed by stacking or mixing multiple types of fibers having different fiber diameters.

[0053]

For reasons related to more reliable control of the proportion of fine fibers so that the proportion of fine fibers on the first surface or the second surface is within the above-described range, the proportion of fine fibers of all constituent fibers in the fibrous web is preferably 20% or more, more preferably 25% or more, and even more preferably 30% or more.

This share is actually 100% or less.

The proportion of fine fibers from all constituent fibers in the fibrous web is the proportion of fine fibers from all constituent fibers in the resulting nonwoven material.

The proportion of fine fibers of all constituent fibers in a fibrous web is the mass fraction (%) of fine fibers of the mass of all constituent fibers forming a fibrous web, and can be obtained based on the weight of fibers used during the manufacture of a nonwoven fabric.

[0054]

In the heat treatment process, heat treatment may be performed continuously on the advancing fibrous web to form a nonwoven material, or heat treatment may be performed intermittently on a predetermined number of fibrous webs to form a nonwoven material. For reasons of easier formation of regions C in which the fibers are fused in a substantially orthogonal state, the fibrous web is preferably heat-treated in a state in which the orientation directions of the fibers intersect with each other, and more preferably heat-treated in a state in which the directions fiber orientations are orthogonal to each other. For example, there is a method in which a heat treatment is performed on a multilayer web in which a plurality of fibrous webs are stacked on top of each other such that fiber orientation directions are different for each fibrous web. The direction of orientation of the fibers in the fibrous web usually corresponds to the machine direction (MD direction) during the manufacture of the fibrous web. In addition, a web in which the fibers are oriented in the MD direction may be oriented in the CD direction prior to heat treatment. In this case, for example, there is a method for laying out the web in the CD direction. The CD direction is a direction orthogonal to the MD direction. The process of providing the desired orientations of the fibers in the fibrous web, described above, is also referred to as "orientation control processing".

[0055]

For the heat treatment process, any heating method can be selected that allows the fibrous web to be heated to form bonded portions by thermal fusion. Examples of such a heating method include a method of spraying a hot air jet (blowing) onto a fibrous web using an air-through method to heat the fibrous web, and a method of heating a fibrous web in an environment without air flow and at a predetermined temperature.

[0056]

The air-through method is a heating method of blowing a fibrous web, which is a raw material for producing a nonwoven fabric, or a nonwoven fabric, with a fluid jet, such as hot air, such as air or water vapor, having a predetermined or higher temperature. . Fluid jet blowing is performed by a so-called air-through-through method (penetration method) in which a fluid such as hot air is passed through the fibrous web or non-woven material. When the nonwoven fabric of the embodiment is made by a heat treatment process using an air-through method, the nonwoven fabric encompasses a nonwoven fabric made by adding a heat treatment process for a nonwoven fabric obtained by another method, or a nonwoven fabric made by any process to be performed after heat treatment process.

[0057]

A heat treatment process using an air-through method will be described. In such a process, the fibrous web is placed on, for example, a resin mesh belt, a metal endless mesh formed from wire mesh, a metal plate with an open air passage or a metal plate without an open air passage, and then the fibrous web is blown with a jet of hot air or steam for thermal fusion of fiber crossing points. Thus, the obtained nonwoven fabric has two surfaces, for example, a surface (hereinafter also referred to as a non-blasted surface) facing the board or mesh, and a surface sprayed with a hot air jet (hereinafter also referred to as a surface exposed to jet blow). In such a nonwoven fabric, multiple bonded areas formed by thermofusion are formed on one surface from these two surfaces. This one surface is typically a surface having a higher proportion of substantially orthogonal fused regions than the other surface.

[0058]

The temperature of the hot air in the conventional through-air treatment is set to a range of about 10°C above the lowest melting point, which is the lowest of the melting points of the constituent fibers in the fibrous web (for example, the melting point of the sheath in a bicomponent core and sheath fiber) , but for reasons related to easier formation of the bonded portion P formed by thermofusion, the temperature difference between the hot air and the lowest melting point of the constituent fiber is preferably 5°C or more, and more preferably 10°C or more.

The temperature difference between the hot air and the lowest melting point of the constituent fiber is preferably 70°C or less, and more preferably 50°C or less.

In the case of a web containing bicomponent core and sheath fibers, for example, when polyethylene is used for the sheath of the fiber, the temperature of the hot air during the heat treatment is 125°C or more, and more preferably 130°C or more for the above reasons.

The hot air temperature is preferably 190°C or less, more preferably 170°C or less.

In addition, when the fiber contains multiple types of resins/polymers, as in the case of a core-sheath bicomponent fiber, the lowest melting point of the constituent fiber is indicative of the melting point of the resin having the lowest melting point. The lowest melting point of the constituent fiber indicates the softening point when the resins do not have a sharp melting point.

[0059]

For reasons of further improving the production efficiency of the nonwoven fabric, in the heat treatment process using the through-air method, the flow rate of hot air blown onto the fibrous web during the heat treatment is preferably in the following range.

The flow rate of the hot air blown over the fibrous web is more than 0 m/s, preferably 0.3 m/s or more, and more preferably 0.5 m/s or more.

The flow rate of the hot air blown onto the fibrous web is preferably 5 m/s or less, more preferably 3 m/s or less, and even more preferably 2 m/s or less.

[0060]

In a heat treatment process using a through-air bonding method, the duration of blowing hot air into the fibrous web (heat treatment time) can be substantially the same as in the prior art method for producing an air-through-bonded nonwoven fabric, but for the same reasons as and above, the heat treatment time is preferably in the following range.

In addition, the duration of the heat treatment is preferably at least 1 second and more preferably at least 3 seconds.

In addition, for reasons related to increasing the manufacturing speed as much as possible and reducing the production cost, the heat treatment time is preferably 60 seconds or less, and more preferably 30 seconds or less.

[0061]

A description will be given of the heat treatment process in the case of a method for heating a fibrous web in an environment without air flow and at a predetermined temperature. In such a process, the fibrous web is placed on, for example, a polymer mesh tape, a metal endless mesh formed from wire mesh, a metal plate with an open air passage hole, or a metal plate without an open air passage hole, and thereafter, the fibrous web is left in an environment with a predetermined or higher temperature for thermofusion of the places of crossing of the fibers. Thus, the obtained nonwoven material has two surfaces, for example, one surface facing the supporting surface of the mesh belt, and another surface opposite this one surface. Of these two surfaces of such a nonwoven fabric, the surface facing the supporting surface of the mesh tape is likely to be smooth and have a good texture. A given surface is typically a surface having a higher proportion of substantially orthogonal fused areas than another surface.

[0062]

In a method for heating a fibrous web in an environment without air flow and at a predetermined temperature, for reasons of easier formation of the bonded portion P formed by thermofusion, the difference between the heating temperature of the fibrous web (hereinafter also referred to as "medium heating temperature") and the lowest the melting point of the constituent fiber is preferably 5°C or more, and more preferably 10°C or more.

This temperature difference is preferably 70°C or less, and more preferably 50°C or less.

For the above reasons, the heating temperature of the medium during the heat treatment is preferably 125°C or more, and more preferably 130°C or more.

In the case of using a core-clad bicomponent fiber, for reasons of better fiber shape retention, the heating temperature of the medium is preferably 190° C. or less, and more preferably 170° C. or less.

[0063]

For the above reasons, the heating time (heat treatment time) of the fibrous web at the heating temperature of the heat treatment medium is preferably at least 1 second, and more preferably at least 3 seconds.

In addition, for reasons of not applying unnecessary heat to the entire nonwoven fabric, the heat treatment time is preferably 180 seconds or less, and more preferably 120 seconds or less.

[0064]

When a nonwoven article, such as the absorbent article described above, includes a constituent element other than the nonwoven fabric of an embodiment, the method for manufacturing such a nonwoven article includes the step of overlapping the nonwoven fabric of the embodiment with the other constituent. For reasons related to improving the feel of the nonwoven article, in particular, increasing the smoothness to the touch, the nonwoven fabric of the embodiment preferably overlaps the other constituent element at such a stage, so that the surface having a lower proportion of connected areas in which the fibers are subjected to thermofusion in a substantially orthogonal state, was facing the other constituent element. In addition, for reasons related to increasing the softness of the nonwoven product to the touch, the nonwoven material of the embodiment preferably overlaps the other constituent element at such a stage so that the surface having a higher proportion of bonded areas in which the fibers are thermally fused to substantially orthogonal state, was facing another constituent element. This nonwoven fabric and another constituting member that overlap each other are combined into a single unit by a known bonding agent such as an adhesive, and thereby a nonwoven fabric is formed.

[0065]

As described above, the present invention has been described based on the preferred embodiments, but the present invention can be modified accordingly and is not limited to the embodiments described above. In addition, the above-described embodiments can be combined as appropriate.

In the nonwoven fabric in the above embodiment, for example, a region C in which the fibers are fused in a substantially orthogonal state is provided on each of both surfaces of the nonwoven fabric, but a region C in which the fibers are fused in a substantially orthogonal state may only be present on one of these surfaces.

[0066]

When an upper limit, a lower limit, or upper and lower limits of a quantitative quantity are specified in the description, the own value of the upper limit or lower limit is also included. In addition, although it is not explicitly stated, it should be understood that all quantitative values constituting the upper limit or less or the lower limit or more, or all quantitative values in the range from the upper limit to the lower limit are described.

In the description, the articles "a" and "an" should be interpreted as meaning "one or more".

It should be understood that various changes and modifications of the present invention can be made in view of the above disclosure in the description. Thus, it should be understood that the present invention can be implemented within the scope of the technical solution based on the claims in the case of embodiments not specifically described in the present description.

All contents of the above patent literature are incorporated herein as part of the contents of the specification.

[Examples]

[0067]

The present invention will be described more specifically with reference to Examples below, but the present invention is not limited to these Examples.

[0068]

<Example 1>

A thermoplastic fiber was used as the initial fiber, and the thermoplastic fiber is composed of a two-component fiber with a concentric core-sheath structure (core-sheath ratio: 50 wt% : 50 wt%, fineness: 1.2 dtex, short fiber) in which the core forming component was formed from PET and the shell forming component was formed from PE. This starting fiber has the lowest melting point of 120°C. Using the starting fiber, a fibrous web was made according to a conventional method using a known carding machine so that the basis weight was 4 g/m ² . The multilayer laminate was formed by stacking five fibrous webs on top of each other so that the machine directions (MD directions) during the manufacture of the fibrous webs were mutually perpendicular at two adjacent fibrous webs. The fibrous webs were subjected to a heat treatment process of blowing hot air through an air-through method in a state where the laminate was placed on the resin mesh tape, and thus a non-woven fabric was produced. The heat treatment conditions in the heat treatment process (the process of passing air through) were as indicated in Table 1.

[0069]

<Example 2>

Using the raw fiber of Example 1, a fibrous web was made according to a conventional method using a known card so that the basis weight was 30 g/m ² and then subjected to an orientation control process. Specifically, the area of the obtained fibrous web was increased by 1.5 times by expanding the fibrous web in the CD direction, so that the length of the fibrous web in the CD direction during manufacture was increased by 1.5 times. Thereafter, the fibrous web was subjected to a heat treatment process of blowing hot air under the same heat treatment conditions as in Example 1 in a state where the fibrous web was placed on the resin mesh tape, and thus a nonwoven fabric was produced.

[0070]

<Example 3>

The nonwoven fabric was made in the same manner as in Example 2, except that the heat treatment conditions were changed and the basis weight in the state before orientation control treatment was changed to 37.5 g/m ² .

[0071]

<Example 4>

As the starting fiber, a thermoplastic fiber with a fineness of 1.2 dtex was prepared, and the thermoplastic fiber is composed of a bicomponent fiber with a concentric core-sheath structure (core-sheath ratio: 50 wt. % : 50 wt. %, short fiber), in in which the core forming component was formed from PET and the shell forming component was formed from PE, and a fiber with fineness of 2.0 dtex was prepared, which is a bicomponent fiber with a concentric core and sheath structure. Using these two types of fibers separately, a multilayer web was made in which a first fibrous web (with a fiber fineness of 1.2 dtex) and a second fibrous web (with a fiber fineness of 2.0 dtex) were superimposed on each other. Such a multilayer web had a ratio of components (mass ratio) corresponding to the ratio of the weight of the first fibrous web to the weight of the second fibrous web, which is 2:3. The first fibrous web and the second fibrous web were laid out in the same direction and subjected to an orientation control process to increase the length in the CD direction by 1.5 times the web (37.5 g/m ² basis weight) made in accordance with the usual method using a known carding machine. Thereafter, a heat treatment process was performed on the multilayer web with the second fibrous web forming a blasted surface. The heat treatment conditions in the heat treatment process (air-through process) were as shown in Table 1. Since the obtained nonwoven fabric was formed from the above two kinds of raw fibers, the proportion of fine fibers of all constituent fibers was 40%.

[0072]

<Example 5>

A nonwoven fabric was made in the same manner as in Example 4, except that the ratio of components (mass ratio) in the multilayer web, corresponding to the weight ratio of the first fibrous web to the weight of the second fibrous web, was 1:4. The proportion of fine fibers from all constituent fibers of the obtained nonwoven material was 20%.

[0073]

<Example 6>

Using the starting fiber of Example 1, the fibrous web was obtained in accordance with the usual method using a known card machine so that the basis weight was 25 g/m ² . The nonwoven fabric was made in the same way as in Example 1, except that such a fibrous web was heated in an environment without air flow and with a heating temperature indicated in Table 1.

[0074]

<Example 7>

A nonwoven fabric was made in the same manner as in Example 6, except that the basis weight of the fibrous web was changed.

[0075]

<Example 8>

The nonwoven fabric was made in the same way as in Example 6, except for using the same multilayer fabric as in Example 4.

[0076]

<Example 9>

The nonwoven fabric was made in the same way as in Example 6, except for using the same multilayer fabric as in Example 5.

[0077]

<Example 10>

Using the same starting fiber as in Example 4, a multi-layered scrim (25 g/m ² basis weight) was produced having a surface density different from that of the multi-layered scrim in Example 4. The multi-layered scrim had the same component ratio (mass ratio) corresponding to the ratio of the weight of the first fibrous web to the weight of the second fibrous web as in Example 4, and was made by performing the orientation control process in the same way as in Example 4. Such a multilayer web was subjected to a heat treatment process under the heat treatment conditions indicated in Table 1, and such the nonwoven fabric was produced in this way.

[0078]

<Comparative Example 1>

Using the starting fiber of Example 1, a fibrous web was produced in accordance with the usual method using a known card machine so that the basis weight was 25 g/m ² . A nonwoven fabric was made in the same manner as in Example 1, except that such a fibrous canvas was used.

[0079]

<Comparative Example 2>

A nonwoven fabric was made in the same manner as in Example 3, except that the fibrous web was made without the orientation control process so that the basis weight was 30 g/m ² .

[0080]

<Comparative Example 3>

A nonwoven fabric was made in the same manner as in Example 4, except that the multilayer web was made without the orientation control process.

[0081]

<Comparative Example 4>

A nonwoven fabric was made in the same manner as in Example 3, except that the fibrous web was made without the orientation control process so that the basis weight was 25 g/m ² .

[0082]

The total number of substantially orthogonal fused areas and that are present in the five viewing areas, and the total number of areas in which the fibers are fused in a parallel state and that are present in the five viewing areas, were determined for each of both surfaces of the nonwoven materials of Examples and Comparative Examples using the method described above. The proportion (%) of substantially orthogonal fused portions was obtained for each of both surfaces using the method described above.

[0083]

Table 1 shows the average fiber diameters of the nonwoven materials used in the Examples and Comparative Examples, and these average fiber diameters were determined in accordance with the method described above. In the Examples (eg Examples 1 and 2) and Comparative Examples using the same starting fiber, the average fiber diameters of the nonwoven fabrics may differ slightly from each other in Table 1 due to the slight difference in the actual measured values. Table 1 also lists the fineness of the fibers along with the average fiber diameters. In the Examples and Comparative Examples using a multilayer scrim, the fineness of the fibers forming the respective layers is shown in Table 1.

The maximum elongation was determined by the method described above for the nonwoven fabric of the Examples and Comparative Examples.

In addition, the proportion of fine fibers was determined by the above method for each of the two surfaces of the nonwoven fabric.

The measurement results are shown in Table 1. Table 1 shows the proportion of fine fibers and the proportion of substantially orthogonal fused portions, on a surface for which the proportion of fine fibers is 20% or more and the proportion of substantially orthogonal fused portions is 35% or more, of of the first surface and the second surface of the nonwovens in the Examples. In addition, Table 1 shows the measurement results for the surface having a higher proportion of substantially orthogonal fused portions from the first surface and the second surface of the nonwovens in the Comparative Examples.

[0084]

[Table 1]

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Fiber Average fiber diameter (µm) 11.7 12.3 12.3 12.9 12.6 11.9 12.2 13.1 12.8 12.7 Tonina (dtex) 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 2.0 2.0 2.0 2.0 2.0 Fiber canvas Multilayer structure five layers one layer one layer two layers two layers one layer one layer two layers two layers two layers Orientation control process No process With process With process With process With process No process No process With process With process With process Heat treatment process Hot air temperature (°C) 136 136 140 140 140 - - - - 160 Hot air flow rate (m/s) 1.7 1.7 2.1 2.1 2.1 - - - - 0.4 Medium heating temperature (°С) - - - - - 140 140 140 140 - Heat treatment time (s) 6 6 6 6 6 60 60 60 60 6 nonwoven fabric Surface density (g/m ² ) 21.9 21.5 24.1 25.6 30.0 25.6 29.9 26.7 30.2 25.0 The proportion of fine fibers from all constituent fibers (%) 100 100 100 40 20 100 100 40 20 40 Proportion of fine fibers (%) 100 100 100 100 100 100 100 100 100 100 The total number of substantially orthogonal fused areas and that are present in the five observation zones (pcs.) 20 18 21 24 25 24 26 24 23 28 The total number of sections in which the fibers are fused in a parallel state and which are present in five observation zones (pcs.) eleven 24 23 25 17 18 21 16 15 25 Proportion of substantially orthogonal fused areas (%) 64.5 42.9 47.7 49.0 59.5 57.1 55.3 60.0 60.5 52.8 Maximum elongation (%) 46.7 49.8 54.6 57.8 53.2 57.3 53.6 51.3 48.4 43.0

[Table 1 - continued]

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Fiber Average fiber diameter (µm) 11.6 11.8 12.6 11.9 Tonina (dtex) 1.2 1.2 1.2 1.2 2.0 Fiber canvas Multilayer structure one layer one layer two layers one layer Orientation control process no process no process no process no process Heat treatment process Hot air temperature (°C) 136 140 140 140 Hot air flow rate (m/s) 1.7 2.1 2.1 2.1 Medium heating temperature (°С) - - - - Heat treatment time (s) 6 6 6 6 nonwoven fabric Surface density (g/m ² ) 22.8 28.5 23.8 20.2 The proportion of fine fibers from all constituent fibers (%) 100 100 40 100 Proportion of fine fibers (%) 100 100 100 100 The total number of substantially orthogonal fused areas and that are present in the five observation zones (pcs.) 12 10 19 14 The total number of sections in which the fibers are fused in a parallel state and which are present in five observation zones (pcs.) 29 21 38 31 Proportion of substantially orthogonal fused areas (%) 29.3 32.3 33.3 31.1 Maximum elongation (%) 60.1 67.5 58.3 70.7

[0085]

As shown in Table 1, on at least one surface of the nonwoven fabric of each Example, the proportion of fine fibers was 20% or more, and the proportion of substantially orthogonal fused portions was 35% or more. As a result, such a nonwoven had a maximum elongation that was less than the maximum elongation of the nonwovens in the Comparative Examples, while containing fine fibers having a fiber diameter of 15 µm or less. From the results shown in Table 1, it can be seen that the nonwoven fabrics in the Examples are less likely to be stretched and hardly experience shrinkage in width due to stretching, unlike the nonwoven fabrics in the Comparative Examples.

Industrial Applicability

[0086]

According to the present invention, there can be provided a nonwoven fabric that contains small fiber diameter fibers and reduced width shrinkage, and a nonwoven fabric product including the nonwoven fabric, an absorbent product, and a method for making the nonwoven product.

Claims (39)

1. A non-woven material having a first surface and a second surface located on the side opposite the first surface, while the non-woven material contains: thermoplastic fibers, wherein the nonwoven material includes orthogonal fused portions in which the fibers are thermally fused in a state in which they cross each other at an angle of 70 to 90° as bonded thermofusion portions in which the crossing points fibers are thermofused, wherein the thermoplastic fibers are short fibers; And fine fibers having a fiber diameter of 15 µm or less, wherein, when at least one of the first surface and the second surface is examined at a magnification of 200 times in the observation zones having a size of 500 μm × 400 μm, the proportion of fine fibers is 20% or more and the proportion of orthogonal fused portions is 35% or more, while the proportion of orthogonal fused sections is the ratio of the number of orthogonal fused sections to the number of connected sections formed by thermal fusion and present in the observation zone. 2. The nonwoven fabric according to claim 1, wherein the proportion of orthogonal fused portions is 50% or more and 80% or less. 3. The nonwoven fabric according to claim 1, wherein the proportion of orthogonal fused areas is less at the location inside with respect to the top side than on that side of at least one of the first surface and the second surface which is top in the thickness direction. 4. The nonwoven fabric according to claim 1, wherein the total number of orthogonal fused portions that exist in the five observation zones is 15 or more and 50 or less. 5. The nonwoven fabric according to claim 1, wherein the total number of orthogonal fused areas that are present in the five viewing zones is less at the location inside with respect to the top side of the nonwoven fabric than on the top side of the nonwoven fabric in the thickness direction of at least one from the first surface and the second surface. 6. The nonwoven fabric according to claim 1, having a basis weight of 5 g/m ² or more and 30 g/m ² or less. 7. Nonwoven fabric according to claim 1, having a maximum elongation of 20% or more and 60% or less. 8. The nonwoven fabric of claim 1, wherein the thermoplastic fiber is a two-component core-sheath fiber including a core and a sheath. 9. The nonwoven fabric of claim 8, wherein the polymeric core component is polyethylene terephthalate and the polymeric sheath component is polyethylene. 10. A nonwoven product comprising the nonwoven fabric of claim 1, wherein the first surface has a higher proportion of orthogonal fusion than the second surface, and the first surface is positioned so that it forms the surface of the nonwoven article. 11. A nonwoven product comprising the nonwoven material of claim 1, wherein the first surface has a higher proportion of orthogonal fusion than the second surface, and the first surface is positioned so that it faces the interior of the nonwoven article. 12. Absorbent article containing the nonwoven material according to claim 1 as a constituent element. 13. An absorbent article according to claim 12, further comprising a top sheet, a back sheet, and an absorbent member positioned between the top sheet and the back sheet, wherein the nonwoven fabric is provided as one or both of the top sheet and the back sheet. 14. An absorbent article according to claim 13, wherein the first surface has a higher proportion of orthogonal fusions than the second surface, and the first surface is located so that it forms the surface of the absorbent article. 15. An absorbent article according to claim 13, wherein the first surface has a higher proportion of orthogonal fusions than the second surface, and the first surface is positioned so that it faces the interior of the absorbent article. 16. The absorbent article according to claim 14 or 15, wherein the nonwoven fabric is provided as the backsheet. 17. The absorbent article of claim 16, wherein the backsheet is formed from a multilayer sheet including a liquid impervious sheet and the nonwoven fabric. 18. A method for manufacturing a product from a nonwoven material, including a nonwoven material having a first surface and a second surface located on the side opposite to the first surface, while the non-woven material contains: thermoplastic fibers, wherein the nonwoven material includes orthogonal fused portions in which the fibers are thermally fused in a state in which they cross each other at an angle of 70-90° as bonded thermofusion portions in which the fiber crossings are thermofused, wherein the thermoplastic fibers are short fibers; And fine fibers having a fiber diameter of 15 µm or less, wherein, when at least one of the first surface and the second surface is examined at a magnification of 200 times in the observation zones having a size of 500 μm × 400 μm, the proportion of fine fibers is 20% or more and the proportion of orthogonal fused portions is 35% or more, while the proportion of orthogonal fused sections, is the ratio of the number of orthogonal fused sections to the number of connected sections formed by thermal fusion and present in the observation zone, wherein the method includes the step of overlapping the nonwoven fabric with a constituent element so that a surface having a lower proportion of orthogonal fused portions faces the other constituent element. 19. The method of manufacturing a nonwoven article according to claim 18, wherein the proportion of orthogonal fused portions on at least one of the first surface and the second surface is 50% or more. 20. A method for manufacturing a nonwoven article according to claim 18 or 19, wherein the nonwoven article is an absorbent article.

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