JPH0461857A - Surface sheet of absorptive article and its manufacture - Google Patents

Abstract

PURPOSE:To allow body liquid to effectively permeate free from the active agent treatment by providing the hydrophobic obverse fiber layer which contacts skin and the hydrophillic rear fiber, layer and reducing the denier No. of the latter in comparison with that of the former, and formig a plurality of opened holes having a prescribed hole diameter in penetration between the obverse side and rear side and keeping a certain opened hole rate. CONSTITUTION:A surface sheet 1 is constituted of the first fiber 2 included in an obverse layer of nonwoven fabric and the second fiber 3 included in a rear layer, and a plurality of opened holes 4 which penetrate through the obverse and rear surfaces of the surface sheet 1 are formed, and the diameter (d) of the opened hole 4 is at least 0.5mm, and the opened hole rate is within a range of 20-50%. With this constitution, the surface sheet 1 is constituted of nonwoven fabric, and provides a soft feeling. The body liquid permeates to an absorbing body, passing through the opened holes 4 of the surface sheet 1, and the dimension of the opened hole can be selected so as to be hardly clogged by the body liquid. Further, when the denier No. of the second fiber 3 on the rear layer is reduced in comparison with the first fiber 2 in the obverse layer the opened hole having the distinct contour can be formed, and since the resistance in the case where in the body liquid passes reduces, the body liquid permeation is accelerated. Further, density can be increased from the overse layer to the rearlayer, and the body liquid permeation is accelerated by the gradient of density.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a topsheet for absorbent articles.

More specifically, sanitary napkins and disposable diapers.

The present invention relates to a top sheet of a disposable absorbent article that forms the surface that comes into contact with the user's skin, such as an incontinence pad.

(Prior Art) In general, with this type of sheet, bodily fluids quickly penetrate into the interior of the article without leaking or spreading on the surface of the article, while bodily fluids once absorbed into the interior of the article can be absorbed by the user. It is required to reduce backflow to the surface due to body pressure and wet the user's skin, and to improve the texture.

Conventionally, in order to provide the required performance to the top sheet,
The top sheet is composed of a surface layer that comes into contact with the user's skin and a back layer that does not come into contact with the user's skin, with the first surface layer having a high density to form a dense paper-like shape, and the back layer having a low density to form a large amount of space. For example, the technology disclosed in Japanese Patent Application Laid-open Nos. 58-55788 and 61-23
949, and on the other hand, a technique was disclosed in JP-A-64-20 in which the fibers constituting the surface layer and the back layer are fused to each other and composited into one piece, so that the density of the surface layer is lower than that of the back layer.
It is disclosed in Japanese Patent No. 844. In addition to this, it is also a known technique to use a perforated plastic film as the top sheet.

(Problems to be Solved by the Invention) It is difficult to simultaneously satisfy all of the above-mentioned required performances with the surface sheet according to the known technique.

For example, with techniques that make the surface layer denser and more densely paper-like, body fluids cannot quickly penetrate into the back surface, and body fluids that remain on the upper surface layer may cause discomfort to the wearer.

On the other hand, the technique described above in which the density of the first surface layer is lower than that of the back layer has a certain permeation effect, but the penetration of body fluids from the surface layer to the back layer and from the back layer to the absorbent body placed on the bottom surface is limited. It relies exclusively on capillary action, and the fibrous tissue is easily clogged, making it difficult to say that the speed of penetration is sufficient. Although it is possible to treat the fibers with an active agent to make them hydrophilic in order to promote penetration, the effect is less long-lasting as the active agent is washed away with the penetration of body fluids, and sometimes the active agent may be absorbed by the wearer. May cause skin irritation. It is therefore also necessary to be able to effectively penetrate body fluids without resorting to active agent treatment.

Therefore, the present invention aims to solve the above-mentioned problem by providing a top sheet of an absorbent article made of a fiber-entangled nonwoven fabric containing at least the 11th I&fiber and the second fiber.

(Means for Solving the Problems) In order to solve the above problems, the gist of the structure of the top sheet according to the present invention is as follows.

At least the surface layer of the top sheet that contacts the skin contains hydrophobic first g fibers, and the back layer thereof contains hydrophobic second fibers. The second fibers are made of fibers having a smaller denier number than the first fibers.

A plurality of openings pass through the surface layer and the back layer.

The pore diameter of the opening is 0.5+s or more, and the porosity is 2.
It is 0-50%. Furthermore, the surface sheet is provided with a protrusion extending downward from the back layer near the periphery of the opening.

(Function) In the top sheet configured as described above, it is made of fiber-entangled nonwoven fabric, and it is possible to give a soft touch with less irritation to the wearer's skin (corresponding to claim 1). ).

Body fluids permeate into the absorbent body through the openings in the topsheet, and the dimensions of the openings can be chosen so that they are not easily clogged by body fluids (corresponding to claim 1).

Reducing the denier number of the second fibers in the back layer compared to the first fibers in the surface layer makes it possible to form pores with clear outlines, and such pores reduce resistance when body fluids pass through. Helps promote fluid penetration. In addition, the density can be increased from the surface layer to the back layer, and body fluid penetration is also promoted by creating a density gradient in this way. Therefore, the accumulation of bodily fluids on the top surface of the top sheet is reduced, and discomfort during wearing is eliminated (corresponding to claim 1).

Furthermore, if the back layer is made to include hydrophilic third fibers in addition to the hydrophobic second fibers, the permeability from the first surface layer to the back layer is further improved. The body fluid that has permeated into the back layer is retained in the lining layer by the water absorbing power of the third fiber, while the hydrophobic nature of the second fiber prevents the body fluid that has permeated into the lining layer from flowing back to the surface layer.
It also acts as a barrier to prevent wetness (also referred to as wetness), improves the dry touch feeling of the surface layer, and more effectively eliminates discomfort when worn (corresponding to claim 3).

By keeping the tips of the protrusions near the periphery of the holes in contact with the absorbent body, they help body fluids penetrate from the surface sheet to the absorbent body by capillary action, and also prevent body fluids that have diffused into the absorbent body. Prevents backflow to the top sheet and reduces the amount of backflow (wet amount) to the top sheet. These protrusions have the effect of separating the top sheet and the absorbent body from each other, and also provide the top sheet with comfortable cushioning properties (corresponding to claim 2).

As mentioned above, when the permeability of the top sheet improves, hydrophilic treatment of the top sheet is no longer necessary (Claim 1)
to 3).

A surface sheet having the above-mentioned properties can be obtained by using a known fiber-entangled nonwoven fabric, and in particular, when the nonwoven fabric is treated with a mesh made of wire as a support in the fluid fiber entangling process, openings and protrusions are formed. It is easy to form (corresponding to claim 4).

Next, embodiments of the present invention will be described below with reference to the drawings.

(Example) FIG. 1 is a perspective view of a topsheet 1 which is an example of the present invention.

The top sheet 1 is obtained from a nonwoven fabric IA, and is composed of first fibers 2 mainly included in the surface layer and second fibers 3 mainly included in the back layer, and has a plurality of openings 4 penetrating the front and back sides of the sheet 1. has. The first fibers 2 are selected from polyolefin fibers, polyester fibers, other hydrophobic fibers, mixtures thereof, composite fibers thereof, and the like.

It is used with a fineness of 3 denier or less and a basis weight of 5 to 20 g/rd. The second fiber 3 is selected from the same fibers as the first fiber 2,
The fineness thereof is preferably set to a denier number of 115 or less of the first fiber 2, and is used at a basis weight of 15 to 45 g/rrr. Examples of low-denier fibers suitable for this purpose include melt-blown fibers and split fibers.

Although the planar shape of the aperture 4 is not specified, it is generally preferable to form it into a substantially convex shape such as a circle, an ellipse, or an ellipse in terms of appearance and other aspects. The hole 4 has a hole diameter d of 0.511I11 or more and a hole area ratio of 20 to 5.
It is in the range of 0%. The hole diameter d is defined as the distance between two tangent lines parallel to the longest chord in the opening 4. The hole diameter d is equal to the diameter of the hole 4 if it is a circle, and is equal to the short axis of the hole if it is an ellipse or an ellipse.

The nonwoven fabric IA is a fiber-entangled nonwoven fabric, and can be obtained by a fluid fiber entanglement treatment method known in nonwoven fabric production, preferably a hydrofiber entanglement treatment method. It is also possible to use a method in which the perforation of the openings 4 is a secondary addition to the nonwoven fabric IA, in which a heating needle is applied to the nonwoven fabric IA to melt the fibers, but more preferably, a fiber entanglement treatment with a fluid is used, For example, in the above water jet fiber entangling treatment method, perforation is performed at the same time as fiber entanglement, the second fiber 3 is attached to a support (not shown) having protrusions as elements for forming the openings 4 and a large number of drainage holes. A fibrous web consisting of a fibrous web and a fibrous web consisting of the first fibers 2 layered thereon is supplied, and high-pressure water of 50 to 80 kg/cd is applied from a large number of spray nozzles to entangle the fibers with each other and move them simultaneously to open them. Nonwoven fabric I with holes 4
You can get A.

FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1, and the top sheet 1 has a surface layer mainly containing first fibers 2, a back layer mainly containing second fibers 3, and cocoon fibers intertwined between the eyebrows.

With the fluid fiber entanglement treatment method as described above, it is possible that the second fibers 3 are mixed in the table 1 and the first fibers 2 are mixed in the back layer, but the first fibers 2 are buried in the second fibers 3 in the first surface layer. The object of the present invention can be achieved as long as the second fibers 3 are not buried in the first fibers 2 in the back layer. The back layer containing many fibers with a small denier number can be formed to have a higher density than the front layer. The cross-sectional shape of the aperture 4 follows the shape of the protrusion on the support in which the aperture 4 is formed, and usually widens from the surface layer toward the back layer.

FIG. 3 shows another embodiment of the present invention, in which the support has elliptical openings 4 obtained by using a wire mesh (not shown) of 10 to 400 mesh made of stainless steel wire, which will be described later. The upper surface of the nonwoven fabric IA is shown.

Figures 4 and 5 show the ■-■ line in Figure 3, respectively.
and a schematic cross-sectional view taken along the line ■-■.

In each cross-sectional view, the surface layer of the nonwoven fabric IA mainly contains first fibers 2, the back layer mainly contains second fibers 3, and the cocoon fibers are intertwined with each other between the layers.

FIG. 5A shows the surface shape of the back layer of the nonwoven fabric IA.
It is a perspective view shown very schematically for easy understanding. The surface has an opening 4, a thin wall portion 15, and a rib-like projection 5.
It is composed of.

FIG. 6 shows a cross section of the nonwoven fabric IA shown in FIG. In the figure, the support body 50 is made of stainless steel wire, consisting of a warp wire 51 and weft wires 61 to 64, but when the wire mesh is viewed from above, the structure is plain weave (not shown).
The gaps between the wires function as drainage holes. Wire rod 5I
However, the portion floating above the wire rods 62 and 64 is the raised portion 53. The part where the wire rod 51 sinks below the wire rods 61 and 63 is the wire rod 61
．． A valley 54 is formed along the wire on both sides of each of the wires 63. Although not shown, gaps serving as drainage holes are formed on both sides of the wire 51 in the valley 54. The nonwoven fabric IA indicated by the two-dot chain line corresponds to the cross-sectional view in FIG.

When the web fed to the support 50 is treated with high-pressure water jets using a large number of nozzles, the constituent fibers of the web are moved around the ridges 53 to form pores 4, and some of the fibers are absorbed by the drainage stream. The protrusion 5 is formed by flowing into the valley 54 together with the protrusion 5. As shown in FIGS. 4 to 5A, the vicinity of the periphery of the aperture 4 is composed of a relatively thin portion, a protrusion 5 extending in a hook-like pattern, and the like. The protrusion 5 extends downward from the nonwoven IA backing layer near the periphery of the aperture 4 .

To obtain the nonwoven fabric IA, the web made of the second fibers 3 is placed on the support body 50 as described above, and the web made of the first fibers is stacked thereon, or the web made of the second fibers 3 is placed on top of the web made of the second fibers 3, or the web made of the First to supply the web.

When the web of first fibers 2 is fed thereafter, the nonwoven fabric I
A back layer containing mainly second fibers is formed on the back side of A, and it is possible to increase the proportion of second Jil fibers 3, especially at the tips of projections 5. In addition, the surface side is mainly the 1i
A surface layer containing T fibers 2 is formed. Both fibers intertwine with each other in the glabella.

The openings 4 and the protrusions 5 are the second fibers 3 having a small denier number.
When used with a predetermined basis weight, the nonwoven fabric IA, which is particularly clearly formed and the melt-blown fiber described above is particularly suitable, is cut to an appropriate size and used as the surface sheet 1.

Table 1 shown below shows the evaluation results compiled for various top sheets obtained by the method of this example and comparative examples in order to determine the comfort when using the product. As a guideline for evaluation, we took into account the amount of wetness and wetness, dry touch feeling, and permeability using the population method.

The openings 4 were formed in a substantially elliptical shape in any of the topsheets, and in the evaluation, attention was paid to the size of the short axis.

Explanations for each item and abbreviation in Table 1 are as follows.

(a) Regarding the first fiber; i) EP: Core-sheath type conjugate fiber consisting of polyethylene and polypropylene, fineness: 1.5d ii) BF-t: Polyethylene fiber, fineness: 0.
1diii) BF-2: Polyethylene fiber fineness 0.3div) PP-1: Polypropylene fiber
Fineness 0.7dv) PP-2: Polypropylene fiber Fineness 1.5dvi) PET-1: Polyester fiber Fineness 0.7dvn) PET-2: Polyester fiber Fineness 1.4d (b) About the second fiber; MB: Polyethylene melt-blown fiber Fineness: 0.06 d (c) Su/wet amount; The method of determining the su/wet amount is as follows: (i) A surface sheet test piece with a size of 150 x 400 mm is prepared using 24 g of crushed pulp and an absorbent polymer. Place 6g on the mixed absorber.

(n) Population method Inject 100 cc into the center of the test piece for about 9 seconds.

(ffl) 5 minutes after the start of injection, 100 XL with known weight
Place 40 sheets of oom filter paper and a 3.5 kg weight on the injection site for 3 minutes, (iv) then leave it for 2 minutes, and repeat the steps (ii) and (i) above.
Repeat the operation ii) and calculate the wet amount using the following formula.

(d) Dry touch feeling; (i) in the above (C) measurement of wet amount; (
It) was performed, and the degree of dryness of the test piece 3 minutes after the start of injection was evaluated by touch.

(e) Penetration; The operations (i) and (5) in (c) measurement of wet amount were performed, and the rapidity of penetration of artificial urine was visually evaluated.

(f) Evaluation symbol: 0 Very Good 0 Good The dry touch feeling is improved by increasing the number of large-diameter hydrophobic fibers in the surface layer.

Test item ■ is the fineness ratio (denier number of first fiber / second
Compared to the first fiber, the dry touch feeling is improved by making the fiber denier number larger than 5.
It is preferable to use fibers with a small denier as the second fibers.

Test item (■) indicates that permeability is improved when the short axis of the opening is 0.5 mm or more.

Test item ■ is all comparative examples, and shows the evaluation results of the top sheet composed only of the first fiber or the second fiber.
With a top sheet made only of primary fibers (fineness 1.5 denier),
The outline of the opening is not clearly formed.

In addition, it is easy to disturb and the shape of the pores collapses, and the effect of the pores on permeability is extremely poor.If the surface sheet is composed only of small denier fibers, there will be a lot of body fluid retained between the fibers. The amount of wetness increases and the dry touch feeling worsens.

No. 7 @ shows yet another implementation S* of the present invention.

The outer shape of the topsheet 1 is the same as that of the nonwoven fabric IA shown in FIG. 3, but the back layer contains hydrophilic third fibers 6, and the end surface thereof is shown in the same manner as in FIG. 5. As the third fiber 6,
5 to 30 fibers such as rayon, cotton, crushed pulp, etc.
It can be used at the rate of g/rd. Non-woven fabric I
To obtain A, the hydroentanglement treatment method described above is used. A large number of third fibers 6 are gathered at the tip of the protrusion 5 .

FIG. 8 is an end view of an example in which the above-mentioned topsheet 1 is used as the topsheet of a disposable diaper 10, and for convenience of explanation, only a portion of the topsheet 1 is schematically shown with particularly exaggerated dimensions. In the figure, a diaper 10 is composed of a top sheet 1, an absorbent core 11, and a back sheet 12 in the thickness direction. The absorbent body 11 is made by compression molding a mixture of pulverized pulp, super absorbent polymer, thermoplastic fiber, etc., and has excellent absorbency and diffusibility of body fluids.The back sheet 12 is made of a water-impermeable plastic film. There is. The tips of the protrusions 5 contact the absorbent body 11 and extend from the surface layer of the topsheet 1 to the absorbent body 11.
This helps in preventing body fluids from penetrating into the absorbent body 11 , preventing body fluids that have penetrated and diffused into the absorbent body 11 from flowing back into the topsheet 1 , and separating the topsheet 1 from the absorbent body 11 .

(Effects) The top sheet of the present invention allows bodily fluids to penetrate into the absorbent body through the openings and also through capillary action between the surface layer and the backing layer, thereby achieving a rapid bodily fluid penetration rate. The back layer is made of small denier fibers, and if appropriate hydrophilic fibers are included here, body fluids will more easily penetrate from the surface layer to the back layer, but will flow back to the surface layer. Therefore, even if hydrophobic fibers are used in the top sheet, it is not necessarily necessary to treat the fibers to make them hydrophilic with an active agent to promote penetration of body fluids.

Providing protrusions around the periphery of the holes effectively prevents the backflow of body fluids that have permeated and diffused into the absorbent body and reduces the amount of wetting. In addition, since the top sheet is separated from the wet absorbent body, the dry touch feeling of the top sheet is improved together with the hydrophobic fibers having a large denier number forming the surface layer. The protrusions also have the effect of giving the top sheet bulkiness and cushioning properties.

Using fluid fiber entanglement process to obtain the top sheet,
It is easy to form the surface layer and back layer of the topsheet, and to form the openings and projections.

[Brief explanation of the drawing]

FIGS. 1 and 2 show a topsheet according to an embodiment of the present invention and its sectional view taken along the line ■-■, and FIGS. 3 to 5 show a topsheet according to another embodiment of the invention and its sectional view. 5A is a schematic diagram showing the back side of FIG. 3, FIG. 6 is a sectional view showing the structure of the support, and FIGS.
The figure is a sectional view showing still another embodiment of the present invention. 1... Surface sheet 2... First fiber 3...
Second fiber 4... Opening 5... Protrusion
6...Third fiber 50...Support (mesh) 51.61.62.63.64...Wire tube 1
Figure d...Pore Diameter Diagram ■ Figure Engraving of Drawing Figure A Figure Figure C Figure Procedure Amendment Form) October 17, 1990 1990 Patent Application No. 172255 2゜ Invention Name of absorbent article top sheet and its manufacturing method 3゜Relationship with the person making the amendment case

Claims (4)

[Claims] (1) In the top sheet of an absorbent article made of fiber-entangled nonwoven fabric, at least the surface layer in contact with the skin contains hydrophobic first fibers, and the back layer contains hydrophobic second fibers, and
The second fibers are composed of fibers having a smaller denier number than the first fibers, and a plurality of holes penetrate between the surface layer and the back layer, and the hole diameter of the holes is 0.5 mm or more. The surface sheet of the absorbent article has a porosity of 20 to 50%. (2) The topsheet according to claim 1, wherein the nonwoven fabric has protrusions extending downward from the backing layer near the periphery of the aperture. (3) The backing layer includes a hydrophilic third fiber in addition to the second fiber.
The topsheet according to claim 1, containing fibers. (4) The method for producing a top sheet of an absorbent article, wherein the openings and projections are formed using a mesh made of wire in the fluid fiber entanglement treatment step for obtaining the nonwoven fabric.