JP5764323B2 - Non-woven fabric and absorbent article using the same - Google Patents

Description

  The present invention relates to a nonwoven fabric and an absorbent article using the same.

  Absorbent articles such as sanitary napkins, panty liners, disposable diapers, etc., depending on the function, those provided with a protruding part on one side of the sheet material, those provided with a line-like protruding part, many Products with small holes have been developed. For example, the one disclosed in Patent Document 1 is provided with a large number of frustoconical protrusions protruding on one side of the sheet. Thereby, it is supposed that it can be set as the sheet material which has cushioning properties suitable for a surface sheet. Patent Documents 2 and 3 disclose a sheet material having irregularities or undulations in which a large number of small holes are provided. Thereby, it is supposed that various physical properties as a surface sheet improve. Patent Document 4 discloses a laminated sheet in which one side of a sheet material is a protruding portion extending in a streak shape, and the cross-section thereof is a kamaboko (substantially semicircular) shape. Thereby, it is supposed that it can be used, for example as a cushioning surface sheet.

JP 2008-28962 A Japanese Patent Laid-Open No. 03-137258 Japanese Patent Laid-Open No. 08-246321 JP 2008-25081 A

The inventors of the present invention have conducted extensive research and development for the purpose of providing a non-woven fabric having a form different from that described above and capable of imparting a property different from the conventional one and a better function. Specifically, the production of a nonwoven fabric having portions protruding on both the front and back surfaces as well as on one side of the sheet material was examined.
In view of the above points, the present invention is suitable for use as a (surface sheet or the like) having good liquid drawability, excellent excretion collecting ability, particularly soft cushioning and good return when pressed. It aims at providing the nonwoven fabric which can do.

  A plurality of first projecting portions projecting to the first surface side and second projecting portions projecting to the second surface side alternately in two directions, ie, the first direction and the second direction within the surface, through the wall portion. The spread nonwoven fabric, wherein the wall portion connects the first projecting portion and the second projecting portion at substantially any location in the plane direction defined by the first direction and the second direction. Nonwoven fabric having fiber orientation along the direction.

  The nonwoven fabric of the present invention has good liquid drawability, excretion excretion, excellent soft cushioning, good return when pressed, and can be suitably used as a surface sheet or the like.

It is a perspective view which shows typically the surface sheet in one Embodiment (Embodiment 1) of the nonwoven fabric of this invention by a partial cross section. It is sectional drawing which expands and shows the area | region II in the nonwoven fabric of FIG. It is sectional drawing which expands and shows the III-III line cross section in the nonwoven fabric of FIG. It is sectional drawing which expands and shows the IV-IV line cross section in the nonwoven fabric of FIG. It is explanatory drawing which shows typically the relationship between a 1st protrusion part and a 2nd protrusion part by planar view. It is explanatory drawing which expand | deploys and shows the state of the fiber orientation of a wall part typically. It is explanatory drawing which shows typically the state of the fiber orientation of a 2nd protrusion part by planar view.

FIG. 1 is a partial cross-sectional perspective view schematically showing a main part of a surface sheet of an absorbent article which is a preferred embodiment (Embodiment 1) of the nonwoven fabric of the present invention. 2 is an enlarged view of region II in the nonwoven fabric of FIG. 1, and FIGS. 3 and 4 are enlarged cross-sectional views showing a cross section taken along line III-III and a line IV-IV, respectively. The nonwoven fabric 10 is preferably applied to a surface sheet of an absorbent article such as a sanitary napkin or a disposable diaper, and the first surface side z ₁ (see FIG. 2) is used toward the skin surface of the wearer. it is preferable to use by placing the second adhesive surface z ₂ to the article inside of the absorber (not shown) side. Hereinafter, although it explains considering the embodiment which uses the 1st surface side toward the wearer's skin surface as mentioned above of nonwoven fabric 10 shown in the above-mentioned drawing, the present invention is limited and interpreted by this Absent.

It is preferable that the nonwoven fabric 10 of this embodiment has the structure continuous in the surface direction. This “continuous” means that there are no intermittent portions or small holes. However, micropores such as interfiber pores are not included in the small holes. When distinguishing this, for example, a small hole can be defined as having a circle equivalent diameter of 1 mm or more. The term “continuous” includes a laminated sheet. In the present embodiment, a single-layer sheet that is not laminated is shown as a preferred embodiment. Further, the meaning of the word “continuous” can also be expressed as the surface on the first surface side z ₁ and the surface on the second surface side z ₂ of the nonwoven fabric being substantially continuous. The term “substantially continuous” here means that, as described above, a small hole may be provided without a small hole as long as the effect of the present invention is not impaired.

  On the first surface side of the nonwoven fabric 10 of the present embodiment, a large number of first protrusions 1 are arranged to extend in an oblique relationship in the plane in two vertical and horizontal directions (hereinafter, this arrangement is referred to as an oblique lattice). Sometimes referred to as an array of shapes). The lattice arrangement may be orthogonal (90 °), and in that case, the lattice arrangement may be distinguished as an orthogonal lattice arrangement. In the present embodiment, it is preferable that the first direction (x) and the second direction (y) (see FIG. 5) in the plane intersect at an angle of 30 ° to 90 °. Furthermore, in this embodiment, many 2nd protrusion parts 2 which protrude in the 2nd surface side of a nonwoven fabric are formed. The second protrusions 2 are also arranged in an oblique grid pattern, but may be an orthogonal grid pattern. Since the preferable range of the crossing angle is determined along with the first protrusion 1, it is the same as described above. The first projecting portion 1 and the second projecting portion 2 project in directions opposite to each other with respect to the sheet surface. In addition, they are arranged alternately in a relationship that is not in the same position in both a plan view and a side view, that is, there is no overlap.

  As described above, the first projecting portion 1 and the second projecting portion 2 that are arranged to extend in the first direction (x direction) and the second direction (y direction) in the plane are continuous in a planar manner without contradiction. The nonwoven fabric 10 is comprised. Here, “continuous without contradiction” means that when a specific shape portion is continuous and becomes planar, it is not refracted or discontinuous, and the whole is continuous with a gentle curved surface. In addition, the arrangement | sequence form of the said 1st protrusion part and the 2nd protrusion part is not limited above, What is necessary is just a form which can be arrange | positioned by the arrangement | sequence which can be continued without contradiction, for example, a hexagonal shape centering on a 1st protrusion part. There may be an arrangement in which six second protrusions are arranged at the vertices and the pattern extends in the plane. In this case, since the number of the second protrusions exceeds the number of the first protrusions, the second protrusions are adjacent to each other. However, as long as a continuous sheet state is formed as a whole, this is the case. Such an arrangement is included in the meaning that the first protrusions and the second protrusions are arranged alternately.

  In this embodiment, the 1st protrusion part 1 and the 2nd protrusion part 2 are made into the truncated cone shape or hemisphere which rounded the top part. In more detail, the protruding shape of the first protruding portion is not sharp but rather hemispherical, while the protruding shape of the second protruding portion is more sharp and rounded at the top or a truncated cone shape. It has become. In the present embodiment, the protruding portion is not limited to the above shape, and any protruding shape may be used. For example, various cone shapes (in this specification, the cone shape is a cone, a truncated cone, a pyramid, a pyramid It is a meaning that widely includes a table, an oblique cone, etc.). In the present embodiment, the first protrusion and the second protrusion hold a frustoconical or hemispherical internal space 1k, 2k having a rounded apex similar to the outer diameter thereof. The internal spaces 1k and 2k are separated from each other via the ridge 6 and are formed as substantially non-continuous spaces. On the other hand, a wall portion 3 is formed between the first protruding portion 1 and the second protruding portion 2 in the sheet thickness direction, and both protruding portions are continuous through the wall portion 3 or the ridge portion 6. It is structured.

Here, the operation based on the basic structure of the nonwoven fabric of the present embodiment described above will be described.
-Cushion property Since the nonwoven fabric of this embodiment has the part which protruded not only on one side of the front and back but on both surfaces, the cushion property peculiar to the structure is expressed. For example, streak-like projections or single-sided projections will inevitably exhibit elasticity as lines or surfaces. However, according to this embodiment, the two-dimensional movement is well followed and supported by points on both sides. Has a three-dimensional cushioning. Moreover, although mentioned later for details, in the wall part 3, it has the orientation of the fiber orientated toward the direction where the wall stands. Therefore, a firm stiffness is born here, and an appropriate cushioning property is realized without the fibers being crushed in the thickness direction. Furthermore, even if the nonwoven fabric is crushed by pressing force due to the fiber orientation of the wall portion described above, the shape restoring force is large, and even if the packing state and wearing are continued, the initial cushioning force is not easily lost.
-Touch The nonwoven fabric of this embodiment has the 1st and 2nd protrusion part in a double-sided direction, The top part is roundish. Therefore, whichever surface is the skin side, a good touch that the top sheet softly contacts the skin with respect to the skin is realized. In addition, the contact point with the pressure at the time of wearing increases or decreases in a planar shape, making it possible to reduce the shape deformation of the entire topsheet against pressure while reducing the shape deformation from pressure deformation. Can also be easy. There also exists an effect | action resulting from said favorable cushioning property, and a unique favorable touch is obtained with the dynamic effect | action by a point contact. Moreover, the point contact mentioned above has an effect also when excretion etc. are received, and the smooth touch is implement | achieved. When supplementing about this smooth touch (absorbing effect), having the orientation of the fiber oriented in the direction in which the wall stands in the wall 3 means that the fiber oriented in the thickness direction of the wall, When the liquid smoothly flows through the fibers, the liquid moves to the absorbent body, and the liquid returns less due to the orientation of the wall fibers, thereby realizing a smooth touch. In addition, the nonwoven fabric itself is excellent in air permeability by maintaining the above-described structure, and is useful for preventing fog due to the effect of point contact.
-Collectability of excrement In the nonwoven fabric 10 of this embodiment, there exist the 1st protrusion part 1 and the 2nd protrusion part 2 which protrude on the both surfaces. Each of them has a first internal space 1k and a second internal space 2k formed therein. Therefore, these can be collected and dealt with in various forms according to the physical properties of the excretion fluid and excrement. For example, when explained on the assumption that the first surface z ₁ of the nonwoven fabric 10 of Figure 1 was the skin side, if a low excrement viscosity high permeability, without passing through the topsheet, the interior space The excrement is temporarily stocked at 2k. On the other hand, if the excretory liquid has a low viscosity and easily permeates, it passes through the top sheet and is collected in the internal space 1k. In any of these cases, the portion that first hits the skin surface is the top 11 of the first protruding portion, and the collected excretory fluid or excrement is made difficult to contact the skin. As a result, after the excretion of urine, feces, menstrual blood, and spillage, a very good and smooth feeling can be sustained widely.

Here, the more detailed characteristic of the nonwoven fabric of this embodiment including the fiber orientation which is a characteristic part in this embodiment is demonstrated based on FIGS. 5-7 which simplified and showed the shape as a model. The nonwoven fabric of this embodiment has the 1st protrusion part 1 and the 2nd protrusion part 2 (it showed with the broken line), and these are each shown as a simple circle in FIG. The sizes of these circles are slightly different for distinction, and do not coincide with the form shown in FIG. In the nonwoven fabric of this embodiment, the 1st protrusion part 1 and the 2nd protrusion part 2 are arrange | positioned by the grid | lattice-like arrangement | sequence. In other words, when the first row k ₁ , the second row k ₂ , and the third row k ₃ are viewed in a predetermined direction, the first protrusion 1 and the second protrusion 2 in each row Are alternately arranged, and when the protrusions of each row are projected in a direction (y direction) oblique to each row within the sheet surface, the first protrusions and the second protrusions are adjacent in the adjacent rows. Overlapping relationship. More specifically, the first protrusion 1 and the second protrusion 2 overlap each other in the n-th row and the (n + 2) -th row. That is, in the present embodiment, when the first protrusion and the second protrusion of the column k ₁ is moved parallel to the y-direction, there is a superimposed relation to the first protrusions and second protrusions of the row k ₃ . However, the present invention is not construed as being limited to this, and there may be a shift between the adjacent first protrusion and second protrusion.

  A wall 3 is formed between the first protrusion 1 and the second protrusion 2. When viewed from the central first protrusion 1 shown in FIG. 5, four wall portions 31, 32, 33, and 34 that are continuous from the four second protrusions 2 are formed. And the four wall part parts 31-34 are connected by wall part part 31 ', 32', 33 ', 34' in the sheet | seat in-plane direction, and the cyclic | annular wall part 3 is comprised in series. . There is a ridge portion that is the back of the horse between the first protrusions adjacent on the first surface side of the wall portions 31 ′, 32 ′, 33 ′, and 34 ′. ) 6 and ridge portions 61 to 64 are formed corresponding to the wall portions 31 ′ to 34 ′, respectively. In the present invention, “annular” is not particularly limited as long as it has an endless series of shapes in plan view, and may be any shape such as a circle, an ellipse, a rectangle, or a polygon in plan view. . In order to maintain the continuous state of the sheet suitably, a circle or an ellipse is preferable. Furthermore, if the "annular" is considered as a three-dimensional shape, a cylindrical shape, a slanted columnar shape, an elliptical columnar shape, a truncated cone shape, a truncated oblique cone shape, a truncated elliptical cone shape, a truncated quadrangular pyramid shape, a truncated oblique pyramid shape Arbitrary ring structures, such as a shape, are mentioned, In order to implement | achieve a continuous sheet | seat state, cylindrical shape, elliptic cylinder shape, truncated cone shape, and truncated elliptical cone shape are preferable. In the present invention, the ridge or the ridge shape means a continuous portion of the mountainous protrusion-like portion between the valley when the internal space 1k of the first protrusion or the internal space 2k of the second protrusion is viewed as a valley. Usually, it has a surface in substantially the same direction as the surface direction of the nonwoven fabric sheet.

FIG. 6A shows a rectangular model obtained by developing the wall 3 shown in FIG. 5, and the lines g _{1a and} g _1b shown therein indicate the fiber orientation directions. In order to represent the position of the wall portion, further, the annular wall portion is a cylinder, and when viewed in a cross section cut by a plane orthogonal to the mother ship, positions different from each other by 90 ° as viewed from the center The code is added. As shown in FIG. 6 (a), the wall portion 3 of the present embodiment has the wall portion standing direction (the first direction) at virtually any location in the plane direction defined by the first direction and the second direction. (The direction connecting the first protrusion and the second protrusion). Here, “substantially” means that a portion having no orientation may be included in part, and it is sufficient that the above-described operation is performed as a whole within a range where each operation is suitably shown. Typically, it means that it does not have different orientations in the MD direction and the CD direction as in the conventional examples described later, and has the predetermined fiber orientation in at least the MD direction and the CD direction. preferable.
“MD” refers to a direction in which a sheet material such as a nonwoven fabric flows during manufacturing, and is an abbreviation of “Machine Direction”. Also called flow direction. “CD” is a direction orthogonal to the MD and is an abbreviation of “Cross Direction”.
In this embodiment, the 0 ° position (wall portion 31) and the 180 ° position (wall portion 33) have their strong orientation (line g _1b ) in a state of being biased toward the second surface side (z ₂ ). On the other hand, the 90 ° position (wall portion 32) and the 270 ° position (wall portion 34) are biased toward the first surface side (z ₁ ), and the strong orientation (line The part indicating g _1a ) is located. Although not shown in the figure because the figures are crowded, the same applies to the wall portions 31 ′ to 34 ′, and the same fiber orientation is obtained over the entire surface. However, the wall portion showing a strong orientation constitutes an orientation structure of an annular wall portion that gradually changes as a whole at the intermediate positions changing as 31, 32, 33, and 34. As described above, the cushioning characteristic peculiar to the present embodiment is thereby produced.
On the other hand, for example, when a dent is given to the nonwoven fabric fused before shaping the fiber web by embossing or the like, the fibers are already fused when the dent is given, so there is a change in the fiber orientation. Usually, an annular wall portion (or a wall portion projected annularly as in the Mercart projection) as shown in FIG. 6B is divided every 90 ° in a plan view. The fiber orientation of the sheet remains, and the fiber orientation changes for each division position. Specifically, the fibers are oriented in the standing direction (line g _1c ) in the wall portions 31 and 33 as shown in the figure, whereas the fibers are oriented in the direction (line g ₂ ) perpendicular to the wall portions 32 and 34. Are oriented. This is because when the nonwoven fabric is usually produced, the fibers are oriented in the MD direction and fused as they are, so the fibers in the wall in the MD direction step are oriented in the CD direction, although the fibers are oriented in the standing direction. The fibers are oriented in a direction perpendicular to the standing direction.

As described above, in this embodiment, the wall portion has an annular shape, and an imaginary line (for example, a one-dot chain line j _{1 in} FIG. 5) along the first in-plane direction passing through the center point of the cross section thereof crosses. The orientation of the fibers differs between the wall portion of the portion and the wall portion crossed by the virtual line (for example, the one-dot chain line j _{2 in} FIG. 5) along the second in-plane direction passing through the center point. The aspect of the difference is that the orientation of the nonwoven fabric before shaping is maintained as in the conventional example, so that the orientation direction does not become different in the wall surface observation, but the fibers are fixed by fusion or the like. It is an aspect that occurs when the orientation of the fiber is changed in the deformation direction together with surrounding fibers by being shaped in the previous state (fiber web and intertwined fiber state).

In the present embodiment, the fiber extends from the first protrusion or the second protrusion to the wall part, particularly in the wall part intersected by a virtual line (for example, the one-dot chain line j _{2 in} FIG. 5) along the second in-plane direction. The orientation changes gradually. Specifically, this gradually changing state is a fiber state in which a nonwoven fabric structure is formed by entanglement (or fusion between fibers) and there is no large gap, but the orientation angle is protruding. It gradually changes from the wall to the wall. Preferably, the size of the gap due to the equivalent circle diameter (direct diameter of the circle when the measured area is regarded as a circle) that can calculate the gap between the fibers from the area of each gap by image analysis of an image or the like is 300 μm or less. In the fiber state, the orientation angle near the protrusion shows a value close to 0 °, and the wall shows a value close to 90 °.

  In the present embodiment, as described above, the fibers of the wall portion have fiber orientation along the direction connecting the first protruding portion and the second protruding portion. That is, the fiber has orientation in the thickness direction. In the present invention, that the fibers have orientation in the thickness direction means that the fibers are aligned in the thickness direction. Specifically, in the measurement method described later, it means that the orientation angle is 50 ° to 130 ° and the orientation strength is 1.05 or more. The degree of fiber orientation in the wall portion is not particularly limited, but when used as a surface sheet for sanitary products or disposable diapers for absorbing body fluid with relatively low viscosity, the fiber orientation is the orientation angle. The orientation strength is preferably 1.1 or more, and the orientation angle is more preferably 70 to 110 °.

FIG. 7 schematically shows the fiber orientation direction (line g ₃ ) in a state where one second protruding portion 2 shown in FIG. 5 is taken out. In order to specify the position, the code | symbol of a wall part is attached | subjected to the corresponding position. As shown in the figure, in this embodiment, the fiber has a radial fiber orientation that converges toward the top 21 of the second protrusion 2. In other words, when the relationship with the wall portion is mentioned together, the fibers are converged from the wall portion 3 to the second protrusion portion 2 so as to converge toward the top portion 21 of the second protrusion portion along the surface direction of the sheet surface. Is oriented. As described above, since there is a radial fiber orientation toward the second projecting portion top portion 21, it has excellent cushioning properties, that is, the formed projecting portion is not easily crushed and is easily recovered even when deformation occurs. Has the effect of.

In the present embodiment, the fiber orientation (q ₁₁ ) of the first protrusion top 11 is different from the fiber orientation (q ₂₁ ) of the second protrusion top ₁₁ . In the present invention, the fiber orientation measurement method is based on the method shown in the examples unless otherwise specified. Here, if the meaning of fiber orientation is mentioned, this is the concept which consists of the orientation angle and orientation strength of a fiber. About fiber orientation, the code | symbol of each part is shown as a subscript, and the value shall mean fiber orientation by the character of "q". In addition, the fiber density (r) and the like are displayed according to the same rules as described above.
In the present embodiment, the first protrusion apex 11 has fiber orientation of the (q ₁₁₎ in the thickness direction, it has the fiber orientation of the (q ₂₁₎ to the second protrusion apex thickness direction Not. Regarding the fiber orientation (q ₁₁ ) at the top of the first protrusion, the orientation angle is 50 ° to 130 °, and the orientation strength is preferably 1.05 or more. Thereby, it becomes easy to move a liquid to a 2nd protrusion part, and the effect which the skin which contact | connects the 1st surface side is kept dry is exhibited. The fiber orientation (q ₂₁ ) at the top of the second protrusion is preferably 0 ° or more and less than 50 ° or more than 130 ° and 180 ° or less, and preferably has an orientation strength of less than 1.05. Thereby, the tensile strength of MD direction and CD direction of a nonwoven fabric sheet can be maintained with sufficient balance, and it can prevent that a sheet | seat is fractured | ruptured or extended at the time of use. When the fiber orientation at the top of the first second protrusion is 1> 2 (q ₁₁ > q ₂₁ ), the first protrusion is more easily deformed by pressure than the second protrusion and is flexible. Has the effect of being excellent in properties and deformability.

In the nonwoven fabric 10 of the present embodiment, the on fiber orientation of the second protrusion apex 21, the fiber orientation in the first surface side (q _21a) and fiber orientation in the second surface side (q _21b) and is substantially Are made equal. Thereby, it has shown that the fiber orientation in radiation | emission toward the above-mentioned 2nd protrusion part top part 21 exists in the 1st surface side and the 2nd surface side, and the formed protrusion part is hard to be crushed, after deformation | transformation Recovery is further enhanced. Moreover, as a surface sheet of an absorbent article, liquid introduction from the front surface to the back surface side is more dominant.

In the present embodiment, the fiber amount (u ₁ ) of the first protrusion and the fiber amount (u ₂ ) of the second protrusion are substantially equal. In the present invention, the method for measuring the amount of fiber is as follows unless otherwise specified. Thereby, it becomes difficult to buckle at the time of deformation due to pressure or the like, and it is preferable that the shape is restored when the pressure is released. Moreover, when the amount of fibers in the nonwoven fabric is substantially equal, the physical property values such as the strength of the nonwoven fabric are stabilized, and it is preferable that the feel change and breakage due to fiber unevenness hardly occur.

In the nonwoven fabric of the present embodiment, the fiber density (r ₁₁ ) of the first protrusion 1 is smaller than the fiber density of the second protrusion (r ₁₂₁ (r ₁₁ <r ₁₂ ). In the present invention, the fiber roughness is measured. Unless otherwise specified, the method is as follows: The fiber density is also described for reference, and the fiber density at the first protrusion is 30 fibers / mm ^{2 to} 150 fibers / mm. mm ² is preferred, from the density of the fiber above reasons in a more preferred. the second protrusions 60 lines ^/ mm 2 to 100 lines / mm ^2, preferably 150 lines ^/ mm 2 to 600 lines / mm ^2, 300 lines / mm ^{2 to} 550 / mm ² is more preferable.
<Measurement of fiber density>
The cut surface of the nonwoven fabric portion was magnified using a scanning electron microscope (adjusted to a magnification (150 to 500 times) at which the fiber cross section can be measured from 30 to 60) (150 times for this example), and the fiber cross section The area of the field of view where the number of fiber cross-sections was measured was determined, and then converted into the number of cross-sections of fibers per 1 mm ² to obtain the fiber density (lines / mm ² ). The average of the fiber density of the sample was measured, and the center of the observation part was the middle point of 11a, 11b or 21a, 21b shown in FIG. The point was the center.
Microscope: JCM-5100 (trade name) manufactured by JEOL Ltd.
<Measurement of fiber amount>
The area measured by the KEYENCE digital microscope VHX-1000 is sufficiently enlarged to enter the field of view (10 to 100 times), and the thickness (S1) of the top of the first protrusion shown in FIG. 2 Measure the thickness (S2) of the top of the protrusion. The measurement is performed 5 times, and the average is defined as the thickness (mm) of the top of the first protrusion and the top of the second protrusion of the sample.
-The number of fibers per 1 mm ^{2 is} measured by the fiber density measuring method described above.
-The amount of fibers was evaluated by measuring the number of fibers (pieces) per ^two thicknesses (mm) x 1 mm. In other words, if the thickness of the top of the first projecting portion and the top of the second projecting portion × 1 mm × the number of fibers per ² were substantially equal, it was determined that the amount of fibers (lines / mm ³ ) was also equal. The term “substantially equal” includes a difference in measurement error range.

In the present embodiment, as described above, the fiber density (r _11a ) of the first surface side z ₁ of the first protrusion 1 and the fiber density (r _11b ) of the second surface side z ₂ are r _11a <r _{By being in} the relationship of _11b , the flexibility and shape maintainability at that portion are compatible. These effects are usually difficult to achieve in this type of nonwoven fabric. However, by providing the above-mentioned specific fiber density, a structure deformation portion and a structure maintenance portion with respect to external pressure are formed at that portion. Thus, the above-described action can be obtained. If it says, since the fiber of the 2nd surface side is "dense" in the top part 11 of a 1st protrusion part, a relatively hard part will become on an arch, and the function of a pier will be performed, The 1st surface The sides are soft and are not rigid in the whole so that sufficient flexibility is maintained.
Fiber density at the first surface side of the first projecting portion is preferably ten ^/ mm 2 to 50 present / mm ^2, the fiber density in the second surface side is preferably 20 present ^/ mm 2 to 100 present / mm ² . More preferably, the fiber density (r _11a ) on the first surface side of the first protrusion is preferably 15 fibers / mm ² to 30 fibers / mm ² , and the fiber density (r _11b ) on the second surface side is 45 fibers. / Mm ² to 70 / mm ² are preferable. In addition to the above-mentioned flexibility and the like, the pulling force of the liquid is an effect obtained by applying the ratio (r _11b / r _11a ) of the fiber density between the first surface side and the second surface side of the first protrusion part by about 2 to 5 times. As a result of the improvement, good liquid permeability can be obtained.

The dimension specification in the nonwoven fabric of this embodiment is demonstrated below.
As for the thickness of the sheet, the thickness at the time of minute pressurization (0.05 × 10 ³ Pa) when viewed as a whole of the nonwoven fabric 10 is referred to as the sheet thickness (T) (hereinafter, T is the value at the time of minute pressurization (0 .05 × 10 ³ Pa)), and the local thickness of the sheet curved into the irregularities is distinguished as the layer thickness (S) (see FIG. 2). The sheet thickness (T) may be appropriately adjusted depending on the application, but considering use as a surface sheet for diapers, sanitary products, etc., 0.5 mm to 10 mm is preferable, and 1 mm to 5 mm is more preferable. By setting it as the range, a suitable cushion feeling can be obtained. The layer thickness may be different at each site in the sheet, and may be appropriately adjusted depending on the application. In consideration of use as a surface sheet for diapers, sanitary products, etc., the layer thickness (S ₁ ) of the top of the first protrusion is preferably 0.2 mm to 3.0 mm, and more preferably 0.6 mm to 2.0 mm. The preferred layer thickness ranges are the same for the layer thickness (S ₂ ) at the top of the second protrusion and the layer thickness (S ₃ ) at the wall. The relationship among the layer thicknesses (S ₁ ), (S ₂ ), and (S ₃ ) is preferably S ₁ > S ₃ > S ₂ . Thereby, in the 1st protrusion part, especially in the skin surface side, the thickness of a fiber layer is high and can implement | achieve favorable skin contact. On the other hand, the wall part, the second protrusion part, and the wall part have a low fiber layer thickness, but the actual basis weight is the same as that of the first protrusion part. It is possible to make a nonwoven fabric with excellent cushioning properties.

In this embodiment, the 1st protrusion part 1, the 2nd protrusion part 2, and the wall part 3 are equally divided into 3 in sheet | seat thickness (T), and the division of each part is defined in this way unless there is particular notice. Accordingly, these thicknesses are naturally determined by the sheet thickness (T) (P ₁ = P ₂ = P ₃ ). However, when the kurtosis or curvature of the tops of the first projecting portion 1 and the second projecting portion 2 are different, a relatively narrow portion that is linear in the cross section is used as the wall portion 3, and the curved portion is rounded and rounded therefrom. optionally a go area as the first projecting portion 1 and the second projecting portions 2 respectively _(P 1, P reference _'2, P' _3). According to the latter definition, in the nonwoven fabric 10 of the present embodiment, the thickness (P ′ ₂ ) of the second protrusion 2 is larger than the thickness (P ₁ ) of the first protrusion 1, and there is a bias in the thickness direction as a whole. It is in the form. In other words, in this embodiment, the radius of curvature of the top portion 11 of the first protrusion top portion 1 is larger than the radius of curvature of the top portion 21 of the second protrusion top portion 2.

The half thickness (t ₁ ) on the first surface side and the half thickness (t ₂ ) on the second surface side are the same as described above. Basically, the line obtained by dividing the sheet thickness (T) into two equal parts is the center line ( It is assumed that the center plane is m and the thicknesses (t ₁ , t ₂ ) are equal. However, if there is a difference in the kurtosis or the radius of curvature at the top of the first protrusion 1 and the second protrusion 2, it is defined by the position m ′ evaluated as the center of the straight section of the wall section. can do. According to the latter definition, the non-woven fabric of the present embodiment satisfies the first-surface-side half thickness t ₁ <the second-surface-side half thickness t ₂ .

  The interval n (see FIG. 5) between the rows of the first protrusions 1 and the second protrusions 2 may be appropriately adjusted depending on the application, but considering that it is used as a surface sheet for diapers, sanitary products, etc. 15 mm is preferable, and 2 mm to 8 mm is more preferable.

Basis weight with the nonwoven fabric of the present embodiment is not particularly limited, in terms of the average value of the entire sheet is preferably 10 to 100 g / m ^2, and more preferably 20 to 50 g / m ^2.

  The manufacturing method of the nonwoven fabric 10 of this embodiment should just employ | adopt a method general to this kind of product suitably. If an example is given, the following aspects will be mentioned. The fiber web before being fused is supplied from the card machine to the web shaping device so as to have a predetermined basis weight. In the web shaping apparatus, the fiber web is conveyed on a base (not shown) having a large number of protrusions and having air permeability. Next, hot air is blown onto the fiber web on the pedestal at a temperature at which each fiber can be appropriately fused to shape the fiber web along the protrusions on the pedestal, and the fibers are fused. The temperature of the hot air at this time is preferably 100 to 180 ° C. and the wind speed is preferably 10 to 100 m / sec in consideration of a general fiber material used for this type of product. In consideration of continuous production, there is a mode in which the pedestal is a conveyor type or drum type that can be conveyed, and the typed nonwoven fabric that is conveyed is wound up by a roll. Note that the MD direction and the CD direction may be directed to the nonwoven fabric of this embodiment.

  The fiber material that can be used for the nonwoven fabric of the present invention is not particularly limited. Specific examples include the following fibers. Polyolefin fibers such as polyethylene (PE) fibers and polypropylene (PP) fibers; fibers using a thermoplastic resin such as polyethylene terephthalate (PET) and polyamide alone; composite fibers having a structure such as a core-sheath type and a side-by-side type, such as A core-sheath structure fiber in which the sheath component is polyethylene or low-melting-point polypropylene is preferable, and typical examples of the core / sheath structure fiber include PET (core) / PE (sheath), PP (core) / PE ( Sheath), fibers having a core-sheath structure such as PP (core) / low melting point PP (sheath). More specifically, the constituent fibers preferably include polyolefin fibers such as polyethylene fibers and polypropylene fibers, polyethylene composite fibers, and polypropylene composite fibers. Here, the composite composition of the polyethylene composite fiber is polyethylene terephthalate / polyethylene, and the composite composition of the polypropylene composite fiber is preferably polyethylene terephthalate / low melting point polypropylene, and more specifically, PET (core). / PE (sheath), PET (core) / low melting point PP (sheath). These fibers may be used alone to form a nonwoven fabric, but may be used in combination of two or more.

  The nonwoven fabric of this invention can be used for various uses. For example, it can be suitably used as a surface sheet of absorbent articles such as disposable diapers, sanitary napkins, panty liners, urine absorption pads and the like. In addition, the form utilized as a wiping sheet etc. is also mentioned.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is limited and interpreted by these Examples.

Example 1
A 2.4 dtex × 51 mm core-sheath type composite fiber having a core of polyethylene terephthalate and a sheath of polyethylene was supplied from the card machine to the web shaping device so as to have a basis weight of 27 g / m ² . In the web shaping apparatus, the fiber web was fixed on a pedestal (MD direction pitch: 8 mm, CD direction pitch: 4 mm) having a large number of protrusions and air permeability. Next, hot air (temperature: 145 ° C., wind speed: 37 m / sec) is blown onto the fiber web on the pedestal to shape the fiber web along the protrusions on the pedestal, and the fibers of each core-sheath structure are fused. I let you. The nonwoven fabric shaped by heat sealing in this manner was taken out and used as a nonwoven fabric test body 1.

(Example 2)
A non-woven fabric specimen 2 was prepared in the same manner as in Example 1 except that the hot air conditions were a temperature of 140 ° C. and a wind speed of 37 m / sec.

(Example 3)
A non-woven fabric test specimen 3 was prepared in the same manner as in Example 1 except that the hot air conditions were a temperature of 140 ° C. and a wind speed of 50 m / sec.

Example 4
A non-woven fabric test specimen 4 was prepared in the same manner as in Example 1 except that the hot air was changed to a temperature of 145 ° C. and a wind speed of 50 m / sec.

(Example 5)
A non-woven fabric specimen 5 was prepared in the same manner as in Example 1 except that the hot air conditions were 150 ° C. and the wind speed was 30 m / sec.

(Example 6)
A non-woven test specimen 6 was prepared in the same manner as in Example 1 except that the hot air conditions were a temperature of 150 ° C. and a wind speed of 37 m / sec.

(Example 7)
A non-woven fabric test body 7 was prepared in the same manner as in Example 1 except that the hot air was set at a temperature of 150 ° C. and a wind speed of 50 m / sec.

(Comparative Example 1)
According to the method described in Example 1 of JP-A-2008-25081, the basis weight was adjusted to prepare a nonwoven fabric specimen c1. Since the nonwoven fabric test body c1 has a streak-like uneven shape, the nonwoven fabric test body c1 does not have an independent recessed part but has an opening. The diaper was produced using the nonwoven fabric test body c1 instead of the nonwoven fabric test body 1 of the example.

(Comparative Example 2)
In the same manner as in Example 1 of JP-A-03-137258, a non-woven fabric having pores was produced. Specifically, it is as follows.
A web composed of polyethylene terephthalate-polyethylene core-sheath fiber 2.4 dtex × 51 mm was formed by a standard carding machine. Next, the web was sandwiched between an uneven net having air permeability and a plain weave net, and air was jetted from the plain weave net side. And the web in which the density part of the fiber was formed in the predetermined pitch was produced by pushing a web into the recessed part of the said uneven | corrugated net. Thereafter, the web in this state was passed through heated air at 140 ° C., and the polyethylene part was welded to integrate the web. Thereby, the uneven | corrugated state was formed with the predetermined pitch, and the nonwoven fabric test body c2 which was opened to the concave part was produced.

(Comparative Example 3)
In the same manner as in Example 1 of Japanese Patent Application Laid-Open No. 08-246321, a nonwoven fabric having apertures was produced. Specifically, it is as follows.
A web composed of polyethylene terephthalate-polyethylene core-sheath fiber 3.3 dtex × 51 mm was formed by a standard carding machine. Next, the web was passed over a plain woven net having air permeability in heated air at 140 ° C., the polyethylene part was welded, and the web was integrated to obtain a sheet-like nonwoven fabric specimen c3. Thereafter, an opening was provided by a pin.

(Comparative Example 4)
A nonwoven fabric specimen c4 was prepared in the same manner as described in Example 1 of JP-A-2008-28962. The nonwoven fabric test body c4 has an independent convex shape, and is used as a sheet material having cushioning properties suitable for the topsheet.

  The following measurement test was performed using the above-mentioned nonwoven fabric test body.

  From the above results, the nonwoven fabric (test body 1) according to a preferred embodiment of the present invention had high fiber orientation in the standing direction in the wall portion, and further maintained the fiber orientation throughout the entire annular wall portion. . In addition, the thickness is suppressed and the KES WE value is extremely high although the basis weight is appropriate, and it is understood that extremely good cushioning properties can be realized in combination with the fiber orientation of the wall portion. .

  The measuring method of each evaluation item including what was performed in the said Example was as follows.

<Weighting>
The basis weight of the nonwoven fabric is measured by the following method. First, the nonwoven fabric is cut into a size of 250 mm × 200 mm, and this is used as a measurement piece. Place this measurement piece on an electronic balance (regardless of manufacturer). The weight in this state is measured, and the weight is divided by the area to obtain the basis weight (gsm). As the measured value, measure 3 points each and adopt the average value.

<Evaluation using KES compression tester>
Using the KES compression tester (Kato Tech Co., Ltd. KES FB-3 [trade name]), the nonwoven fabric was subjected to compression characteristic evaluation up to 5.0 × 10 ³ Pa in the normal mode, and the following compression performance was read. .

<Measurement of sheet thickness (T)>
Using a KES compression tester (Kato Tech Co., Ltd., KES FB-3), the nonwoven fabric was subjected to a compression property evaluation up to 5.0 × 10 ³ Pa in a normal mode, and at a minute pressure (0.05 × 10). The thickness (T) of ³ Pa) was read from the chart. As the measured value, measure 3 points each and adopt the average value.
<Measurement of thickness under pressure in the compression direction>
Using a KES compression tester (KES FB-3, manufactured by Kato Tech Co., Ltd.), the nonwoven fabric is subjected to compression characteristic evaluation up to 5.0 × 10 ³ Pa in a normal mode, and when 3.5 × 10 ³ Pa is applied. The thickness of was read from the chart. As the measured value, measure 3 points each and adopt the average value. This value is preferably 0.8 to 2.0.

<Measurement of thickness under pressure in the return direction>
Using a KES compression tester (KES FB-3 manufactured by Kato Tech Co., Ltd.), the non-woven fabric was evaluated for compression characteristics up to 5.0 × 10 ³ Pa in the normal mode, and 3.5 × 10 ³ at the time of decompression. The thickness at Pa pressurization was read from the chart. As the measured value, three points are measured and the average value is adopted. This value is preferably 0.6 to 1.8.

<Measurement of cushioning properties>
Using a KES compression tester (KES FB-3, manufactured by Kato Tech Co., Ltd.), the nonwoven fabric is subjected to compression characteristic evaluation up to 5.0 × 10 ³ Pa in a normal mode, and when 3.5 × 10 ³ Pa is applied. The thickness was read from the chart, and the value was divided from the thickness T to evaluate the cushioning property. As the measured value, measure 3 points each and adopt the average value. This value is preferably 37-80%.

<Measurement of fiber orientation>
Using a scanning electron microscope manufactured by JEOL Ltd .; JCM-5100 (trade name), the sample is allowed to stand so that the z-axis direction in FIG. An image taken from the direction of (1) was printed (enlarged to a magnification capable of measuring 10 or more fibers to be measured; 50 to 300 times), and the fibers were traced on a transparent PET sheet. The said image was taken in in the personal computer and the said image was binarized using the NexusNewQube [brand name] (brand name) (stand-alone version) image processing software. Then, using Fiber Orientation Analysis 8.13 Single (software name), which is a fiber orientation analysis program, an orientation angle and orientation strength were obtained from the binarized image. The measurement results for each specimen are shown in Table 1. The orientation angle indicates the angle at which the fibers are most oriented, and the orientation strength indicates the strength at the orientation angle. In the measurement of the wall portion, the orientation angle close to 90 ° indicates that the fibers are oriented in the standing direction. In addition, the larger the orientation strength value, the more the fibers are aligned. The case where the orientation strength is 1.05 or more is assumed to be oriented.
5, assuming that the wall portion 32 (or 34) in the assumed MD direction (line j ₁ ) is the wall portion (MD), the wall portion in the assumed CD direction (line j ₂ ). The fiber orientation of both of them is measured so that 31 (or 33) becomes the wall (CD). As the measured value, three points are measured and the average value is adopted.

<Measurement of absorption time (reference)>
Remove the surface sheet from Kao's commercially available baby diapers (trade name "Merry's Sarasara Air-Through M size"), and stack a non-woven fabric test piece cut into 100 x 250 mm, and fix the surrounding area for evaluation. I got a baby diaper. A load of 20 g / cm ² was evenly applied on the non-woven fabric test piece, a cylinder with a cross-sectional area of 1000 mm ² placed at the approximate center of the test piece was applied, and artificial urine was injected therefrom. As the artificial urine, physiological saline was used, and the artificial urine was injected three times by 40 g every 10 minutes, and the time (second) to be absorbed was measured.

DESCRIPTION OF SYMBOLS 1 1st protrusion part 11 1st protrusion part top part 11a 1st protrusion part top part 1st surface side 11b 1st protrusion part top part 2nd surface side 1k 1st protrusion part Internal space 2 2nd protrusion part 21 2nd protrusion part top part 21a second projection top first surface 21b second protrusion top second face 2k second projecting portion internal space 3 wall 6 ridges 9 projections 10 nonwoven T sheet thickness _{S (S 1, S 2,} S 3) Layer thickness

Claims (7)

A plurality of first projecting portions projecting to the first surface side and second projecting portions projecting to the second surface side alternately in two directions, ie, the first direction and the second direction within the surface, through the wall portion. The spread nonwoven fabric, the wall portion converges toward the top of the second protruding portion at virtually any location in the plane direction defined by the first direction and the second direction , Nonwoven fabric having radial fiber orientation. The fiber density r ₁₁ of the top portion of the first protrusion nonwoven fabric according to claim 1 less than the fiber density r ₁₂ of the top portion of the second projecting portion.   The wall portion has an annular shape, a wall portion portion of a portion intersected by an imaginary line along the first in-plane direction passing through the central point of the cross section thereof, and in the second in-plane direction passing through the central point. The nonwoven fabric according to claim 1 or 2, wherein the orientation of the fibers is different depending on a wall portion crossed by the virtual line along. The orientation angle in the said wall part is 50 degrees or more in both MD / CD directions, The nonwoven fabric of any one of Claim 1 to 3. The nonwoven fabric according to any one of claims 1 to 4, wherein the orientation strength of the wall portion is 1.05 or more in both MD / CD directions. The nonwoven fabric according to any one of claims 1 to 5, wherein the fiber orientation at the top of the first protrusion is different from the fiber orientation at the top of the second protrusion. Fiber orientation q at the top of the first protrusion ₁₁ Is the fiber orientation q at the top of the second protrusion. ₂₁ The nonwoven fabric according to any one of claims 1 to 6, which is larger.

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