JP3877923B2 - Liquid-permeable composite sheet for disposable body fluid absorbent articles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid-permeable composite sheet suitable for use in disposable body fluid absorbent articles such as disposable diapers and sanitary napkins.
[0002]
[Prior art]
FIG. 6 is a perspective view of the micro-opening plastic sheet 110 having a soft feel as disclosed in Japanese Patent Laid-Open No. 62-57551. This plastic sheet is suitable for use as a surface sheet of a disposable diaper. A large number of cylindrical protrusions 120 are formed on the surface of the sheet 110, and a minute opening 125 is formed on the top of the protrusion 120. ing. Such a sheet 110 is described as being flexible and exhibiting a cloth-like feel.
[0003]
FIG. 7 is a perspective view of a sanitary napkin 200 disclosed in Japanese Patent Laid-Open No. 7-328061. The surface sheet 210 of the napkin 200 includes a nonwoven fabric 211 and a plurality of strip-shaped plastic sheets 212 joined to the upper surface of the nonwoven fabric 211. The strip-shaped plastic sheets 212 are parallel to each other and extend in the longitudinal direction of the napkin 200. ing. In the napkin 200, dirt due to menstrual blood can be concealed by the presence of the plastic sheet 212.
[0004]
[Problems to be solved by the invention]
One method of using the known micro-opened plastic sheet 110 as a sanitary napkin surface sheet to conceal dirt due to menstrual blood in the absorbent core located below the surface sheet is as follows. Filling with inorganic particles such as calcium and barium sulfate. Moreover, what is necessary is just to increase the filling amount of the particle | grains, in order to raise concealment power. However, if only the filling amount is increased, the strength of the sheet will decrease, or the thickness fluctuation width at the time of manufacturing the sheet will increase, so the problem will be solved by increasing the thickness of the sheet used. Must. However, by doing so, the sheet becomes highly rigid and loses the cloth-like feeling, and the cylindrical protrusion 120 may also be poor in flexibility.
[0005]
The Japanese Patent Laid-Open No. 7-328061 teaches that the hiding power can be improved by adopting the belt-like plastic sheet 212 for the surface sheet 210 made of a relatively flat sheet such as a nonwoven fabric. For the plastic sheet having the cylindrical protrusion 120, it does not teach how to use the belt-shaped plastic sheet.
[0006]
This invention makes it a subject to provide a soft touch and high hiding power to a liquid-permeable sheet used for, for example, a surface material of a disposable body fluid absorbent article with reference to these prior arts. .
[0007]
[Means for Solving the Problems]
[0008]
In order to solve the above problems, the present invention is directed to a disposable body fluid-absorbing article having a plastic sheet layer on the upper surface side and a fiber assembly layer bonded to the plastic sheet layer on the lower surface side. It is a liquid-permeable composite sheet used for the above.
[0009]
In such a composite sheet, the invention is characterized in that the plastic sheet layer has a plurality of strip-shaped material portions extending in parallel and spaced apart from each other in one direction, and is substantially bonded to the strip-shaped material portion. consists of a total of not covering the strip material portion thin film material portion is thin than the set layer top surface, the said thin film material portion, while joining said material web portion on its upper surface, a lower surface side A plurality of liquid- permeable apertures are formed along the edge of the apertures , and the fiber assembly layers are joined to each other and the strip-shaped material portions adjacent to each other are intermittently arranged in the one direction. An upright portion extending upward from the upper surface of the composite sheet is formed while repeating undulations .
[0010]
The present invention has the following preferred embodiments.
[0011]
[0012]
[0013]
[0014]
A mode in which the plastic sheet layer contains an inorganic filler, and the content of the filler per unit area in the strip-shaped material portion is higher than that in the thin-film material portion.
[0015]
[0016]
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The details of the liquid-permeable composite sheet used in the disposable body fluid-absorbing article and the method for producing the same will be described with reference to the accompanying drawings.
[0018]
FIG. 1 is a partially broken perspective view of a sanitary napkin 1 which is an example of a disposable body fluid absorbent article. The napkin 1 includes a liquid-permeable top sheet 2, a liquid-impervious back sheet 3, and a liquid-absorbent core 4 interposed between the two sheets 2 and 3. In the line 6, they are overlapped at the part extending from the peripheral edge of each other and joined together by welding or adhesion. The napkin 1 has a width extending in the X direction and a length extending in the Y direction. In such a napkin 1, the composite sheet according to the present invention is used as the top sheet 2.
[0019]
2, 3, and 4 are a partially enlarged view of the napkin 1 and sectional views taken along lines III-III and IV-IV, respectively. However, the back sheet 3 and the core 4 are indicated by virtual lines. The top sheet 2 is a composite sheet composed of a plastic sheet layer 11 located on the upper surface side thereof and a nonwoven fabric layer 12 that is an aggregate of fibers 13, and these layers 11 and 12 are bonded to each other by welding or adhesion. is doing. The plastic sheet layer 11 includes a plurality of strip-shaped material portions 16 extending in the Y direction in parallel to each other, and a thin-film material portion 17 that is below the strip-shaped material portion 16 and covers substantially the entire upper surface of the nonwoven fabric layer 12. These two parts 16 and 17 are made of thermoplastics and are welded to each other at the overlapping parts. The thin film material portion 17 includes a plurality of substantially flat portions 18 extending in the Y direction in parallel to each other and a plurality of apertures 19 extending between the adjacent flat portions 18 and extending in the Y direction. A bridge portion 20 extending in the X direction from the opposite edge portions 21 in the adjacent flat portions 18 and crossing the opening 19, and a standing portion 22 extending upward in the figure at the edge 21 of the flat portion 18. The standing portion 22 is a portion having a generally sawtooth shape extending in the Y direction while repeating irregular undulations.
[0020]
The nonwoven fabric layer 12 is joined to the flat portion 18 of the thin film material portion 17 from below in the figure, and a part of the nonwoven fabric layer 12 is exposed in the opening 19.
[0021]
As the back sheet 3, a thermoplastic sheet, a nonwoven fabric made of thermoplastic synthetic fibers, a laminate of these sheets and the nonwoven fabric, or the like is used.
[0022]
For the core 4, pulverized pulp, a mixture of pulverized pulp and a superabsorbent polymer, or the like is used.
[0023]
3 and 4, the band-shaped material portion 16 is provided on the flat portion 18 of the thin-film material portion 17, preferably on each of the flat portions 18, and has a thickness of 0.01 to 0.3 mm and 0. And a width S1 of ₁ to 4 mm. When the thickness is less than 0.01 mm, the effect of enhancing the concealability of the thin film material portion 17 is poor, and when the thickness exceeds 0.3 mm, the rigidity becomes high and the skin irritation becomes too strong. There is. The width S ₁ is approximately the same as that of the flat portion 18 or smaller. However, the width S ₁ is preferably not less than 1/3 of the width W ₁ of the flat portion 18 in order to improve the concealability in the flat portion 18, and should not be less than 1/2. More preferably. Such a strip-shaped material portion 16 is obtained by extruding a thermoplastic plastic into a strip shape and supplying it onto the thin-film-shaped material portion 17. Or an oval shape.
[0024]
The band-shaped material portion 16 should function so that menstrual blood absorbed in the core 4 by the napkin 1 in FIG. 1 does not appear through the top sheet 2, that is, to improve the concealing property of the top sheet 2. is there. An inorganic filler such as titanium oxide or barium sulfate is added to such a band-shaped material portion 16, and a dye or pigment may be added as necessary. These addition amounts can be increased within a range that does not hinder the extrusion of the band-shaped material portion 16. When the amount of the inorganic filler added is large, the strip-shaped material portion 16 having a narrow width and a large thickness is easier to extrude than the thin film-shaped material portion 17 having a large width and a small thickness, and the strip-shaped material portion. Since the portion 16 has little influence on the performance of the topsheet 2 even if the thickness varies, the use of such a strip-like material portion 16 makes it easy to increase the hiding power of the topsheet 2. When the topsheet 2 is viewed from above, the content of the inorganic filler per unit area of the strip-shaped material portion 16 is higher than the content of the thin film material portion 17, and preferably the former content is the latter content. Is at least 1.3 times greater. The strip-shaped material portion 16 can also contribute to the improvement of the tensile strength in the Y direction of the thin-film material portion 17.
[0025]
The flat portion 18 of the thin film material portion 17 has a thickness of 0.001 to 0.05 mm and a width W ₁ of 0.3 to 5 mm between the openings 19 and 19. The majority of opening 19 extends long in the Y direction, preferably has a width _{W 2} of 0.03～5Mm, a length of at least 1.5 times the width _{W 2.}
[0026]
The bridge portion 20 of the thin film material portion 17 is located between the openings 19 and 19 aligned in the Y direction, and has an arc 20A that protrudes upward from the flat portion 18. As with the flat portion 18, there is a flat portion 20B (see FIG. 2). The arcuate bridge portion 20A has a proximal end 25A that appears to extend from the flat portion 18 and a proximal end 25B that appears to extend from the top 27 of the raised portion 22. (See Fig. 2). The preferred bridge portion 20 has a thickness equal to or less than that of the flat portion 18 and has a width W ₃ extending in the Y direction (see FIG. 3) in the range of 0.001 to 2 mm at the narrowest portion. .
[0027]
Raised portions 22 of the thin film material portion 17, a portion of the thin film at the edge 21 of the majority of those flat portions 18 is formed by extending upward in the drawing, the base end portion 26 connected to the flat portion 18 And a free end portion 27 extending upward from the base end portion 26. The upper edge 27 </ b> A of the upright portion 22 repeats serrated undulations along the edge 21. The maximum value of the height from the flat portion 18 to the upper edge 27A can reach about 5 mm. However, in order to improve the touch of the topsheet 2, the maximum value is suppressed to about 1 mm and the majority of the standing portions 22. Preferably protrudes from the upper surface of the strip-shaped material portion 16. A part 22B of the standing part 22 is formed at the edge of the bridge part 20 (see FIG. 2).
[0028]
An example of a mode in which the upper edge 27A of the upright portion 22 repeats undulations is as shown in FIG. 3, and includes a hypotenuse 31 that extends substantially to the upper right, a hypotenuse 32 that extends substantially to the left, and between these hypotenuses 31 and 32. This is an irregular connection of a portion 33 having a triangle or a shape similar to a triangle formed by the base end portion 26 extending in the direction. The standing portion 22B may also repeat undulations. The upright portions 22 including the upright portions 22B have the same thickness as the flat portion 18 or thinner than the flat portions 18, and are deformed flexibly when touched by human skin, like the velvet on the top sheet 2. A smooth and flexible feel can be given. Although it is not easy to visually check each of the raised portions 22, when there are a large number of raised portions 22, the surface of the topsheet 2 appears to be raised. Further, the standing portion 22 can diffusely reflect the incident light beam on the top sheet 2 to reduce the surface gloss often seen in the plastic sheet.
[0029]
Generally, adding a large amount of an inorganic filler to a thin film such as the thin film material portion 17 makes it difficult to manufacture the thin film. Therefore, the surface sheet 2 does not obtain a high hiding power with respect to the soiled core by the thin film material portion 17, but obtains the hiding power by the band material portion 16, so that the thin film material portion 17 These two parts 16 and 17 are properly used so as to improve the appearance and the touch.
[0030]
The nonwoven fabric layer 12 may contain at least 70% by weight of thermoplastic synthetic fiber, and may further contain up to 30% by weight of hydrophilic chemical fiber such as rayon fiber, and hydrophilic natural fiber such as cotton fiber and pulp fiber. An example of a preferable nonwoven fabric layer 12 is made of a thermoplastic synthetic fiber having a fineness of 0.55 to 16.5 dtex (0.5 to 15 d) and a basis weight of 5 to 50 g / m ^2. In addition to thermal bond nonwoven fabrics such as spunbond nonwoven fabrics, point bond nonwoven fabrics, and air-through nonwoven fabrics, there are melt blown nonwoven fabrics and spunlace nonwoven fabrics.
[0031]
When such a surface sheet 2 is used for the sanitary napkin 1, menstrual blood is absorbed into the core 4 through the non-woven fabric layer 12 from the opening 19. The core 4 and the nonwoven fabric layer 12 soiled by menstrual blood are covered with the band-shaped material portion 16 having high concealing power, the standing portion 22 that irregularly reflects light rays, etc., and the stain is not conspicuous.
[0032]
[0033]
FIG. 5 is a drawing showing steps for continuously producing the composite sheet 108 used as the top sheet 2 of FIG. From the left side of the figure, the second web 102 which is a fiber assembly to be the nonwoven fabric layer 12 of FIG. 2 is continuously supplied. The upper surface 102A of the second web 102 is made of the first thermoplastic plastic discharged from the first extruder 121, and the one first web 101 to be the thin film portion 17 of the top sheet 2 is softened by heat. In this state, the two webs 101 and 102 are welded together to form the first composite web 104.
[0034]
In the first composite web 104, the third web is a plurality of strips 116 made of the second thermoplastic plastic discharged from the second extruder 122 on the first web 101 and parallel to each other and spaced apart from each other by a predetermined dimension. The first web 101 and the third web 103 are welded between the pair of compression rolls 174 to form the second composite web 106. The band 116 of the third web 103 becomes the band-shaped material portion 16 of the top sheet 2.
[0035]
The second composite web 106 proceeds to the first processing zone 123, and a high-pressure columnar water stream is applied to the upper surface 101 A of the first web 101 from a plurality of nozzle rows 123 A arranged at a required pitch in the width direction of the second composite web 106. The third composite web 107 is obtained by being jetted toward the vehicle. The first web 101 is selectively broken between the belts 116 and 116 by the columnar water flow, and the first web 101 is formed with a row of apertures arranged intermittently in the traveling direction of the third composite web 107, Such aperture rows are arranged in parallel to each other in the width direction of the third composite web 107. In the first treatment zone 123, in order to form a plurality of aperture rows, columnar water flows are ejected from the rows of the second and third nozzle rows 123B and 123C as shown in addition to the nozzle row 123A if necessary. can do. In these nozzle rows 123A, 123B, and 123C, it is preferable that the nozzle positions in the width direction of the third composite web 107 are substantially matched with each other so that the trajectories of water flow overlap. A suction mechanism 124 that sucks the jetted water is provided below the first treatment zone 123.
[0036]
The third composite web 107 proceeds to the second processing zone 127. In the second processing zone 127, nozzle rows 127A, 127B, 127C and a suction mechanism 128 that form a row in the width direction of the third composite web 107 are provided. Here, a high-pressure columnar water stream is jetted onto the lower surface 102B of the second web 102 forming the third composite web 107, and then dried to form a composite sheet 108. In the composite sheet 108, the portion of the first web 101 that has already been broken in the first processing zone 123 is deformed so as to follow the direction of the columnar water flow in the second processing zone 127, and from the lower surface 101B of the first web 101. It extends in the direction toward the upper surface 101A. The trajectory of the jet water flow by the nozzle rows 127A, 127B, and 127C in the second processing zone 127 does not necessarily need to coincide with the trajectory by the nozzle rows 123A, 123B, and 123C in the first processing zone 123. If they match, the first web 101 is broken over a wide range to form a long opening, and many of the broken portions extend above the upper surface 101A of the first web 101. According to the manufacturing method according to the present invention, a required portion in the width direction of the first web 108 is selectively broken, and a plurality of aperture rows extending in parallel to each other in the machine direction are easily formed.
[0037]
In the composite sheet 108, the first and second webs 101 and 102 to be bonded to each other become the plastic layer 17 of the top sheet 2, and the opening formed in the first web 101 becomes the opening 19, and the torn portion of the first web 101 Becomes the upright portion 22. A portion of the opening row arranged in the supply direction of the first web 101 and not broken by the high-pressure columnar water flow between the opening portion and the opening portion becomes a bridge portion 20.
[0038]
In FIG. 5 , the nozzle diameters of the nozzle rows 123A to 123C and 127A to 127C are 0.05 to 0.15 mm, the pitch between adjacent nozzles in each nozzle row is 0.1 to 0.5 mm, and the water pressure of the columnar water flow is 2942. -19614 kps (30-200 kg / cm ² ), and the suction pressure is preferably 200-1000 mmH ₂ O. In the first and second processing zones 123 and 127, the web to be processed is placed on supports 131 and 132 such as a mesh screen and moved in a required direction.
[0039]
When the first web 101, the second web 102, and the third web 103 are supplied at room temperature, these webs are welded between a pair of heated rolls, or bonded with a hot melt adhesive or the like. Can be joined.
[0040]
If necessary, the first web 101, the second web 102, and the third web 103 can be subjected to water repellent treatment or other surface treatment at an appropriate position in the illustrated process. If the first web 101 is a film that is uniaxially stretched along the supply direction, it may be easy to form an opening by a columnar water flow. The first web 101 has a thickness of 0.001 to 0.05 mm, and the third web 103 has a thickness of 0.01 to 0.3 mm and a width of 0.1 to 4 mm. As the second web 102, one having a basis weight of 5 to 50 g / m ² is used. In the process of FIG. 5 , the first treatment zone 123 is omitted, and the high pressure columnar water stream is jetted only in the second treatment zone 127, thereby removing the composite sheet 108 from the first composite web 106 without forming the second composite web 107. It can also be manufactured. However, in such a manufacturing method, since the columnar water flow hardly acts directly on the first web 101, the first web 101 is likely to have narrow openings and many bridge portions. The composite web 108 is appropriately dried before it is wound up. Further, in the process of FIG. 5 , the second composite web 107 can be taken out from the illustrated process and used as the top sheet 2. In this case, the surface sheet 2 has almost no standing portion 22 at the edge 21 of the opening 19.
[0041]
[0042]
【The invention's effect】
Since the composite sheet according to the present invention is formed of a plurality of strip-shaped material portions and a thin film-shaped material portion to be joined thereto, when the composite sheet is used as a top sheet of a disposable diaper or a sanitary napkin, The dirt on the core can be reliably concealed at the part where the parts overlap. The strip-shaped material portion also helps to improve the tensile strength of the thin-film material portion in the direction in which it extends.
[0043]
[Brief description of the drawings]
FIG. 1 is a partially cutaway perspective view of a sanitary napkin.
FIG. 2 is a partially enlarged view of FIG.
3 is a cross-sectional view taken along line III-III in FIG.
4 is a cross-sectional view taken along line IV-IV in FIG.
FIG. 5 is a manufacturing process diagram of a composite sheet.
FIG. 6 is a diagram showing an example of a conventional technique.
FIG. 7 is a perspective view of a sanitary napkin showing another example of the prior art.
[Explanation of symbols]
1 Body fluid absorbent article (Sanitary napkin)
2 Composite sheet (surface sheet)
DESCRIPTION OF SYMBOLS 11 Plastic sheet layer 12 Fiber assembly layer 16 Band-shaped material part 17 Thin film-like material part 19 Opening 22 Standing part 101 Thin film (1st web)
102 Fiber web (second web)
103 belt (3rd web)
108 Compound web

Claims (2)

It has a plastic sheet layer on the upper surface side and a fiber assembly layer bonded to the plastic sheet layer on the lower surface side, and is a liquid-permeable composite sheet used for disposable body fluid absorbent articles,
The plastic sheet layer is a strip material portion of the plural rows extending in spaced apart parallel to one direction, than the whole not covering the strip material portion of substantially the fiber assembly layer top surface joined to the strip material portion A thin- film material portion having a small thickness, and the thin- film material portion is bonded to the upper surface side of the band-shaped material portion, the lower surface side of which the fiber assembly layer is bonded, and the adjacent A plurality of liquid-permeable apertures that are intermittently arranged in the one direction between the strip-shaped material portions, and an upright portion that extends above the upper surface of the composite sheet while repeating undulations along the edges of the apertures The composite sheet is characterized in that is formed . The composite sheet according to claim 1, wherein the plastic sheet layer contains an inorganic filler, and the content of the filler per unit area in the strip-shaped material portion is higher than that in the thin-film material portion.

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