JPS6215301A - Disposable diaper - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Industrial Application Field This invention not only fits well on the body and has a soft feel, but also has good drainage properties even if the contact surface gets wet, so it dries quickly and becomes saran. This article relates to disposable diapers that give a sense of touch.

Conventional paper diapers are basically made of non-woven fabric made of non-water-absorbing fibers using polyester, polypropylene, etc. as the surface material, composite water-absorbing materials using crepe paper, cotton-like pulp, water-absorbing resin, etc. as the water-absorbing material, and waterproof materials. Backing sheets using polyethylene film or the like are laminated in various shapes and structures, and accessory members such as adhesive tape for wearing on the body and rubber bands for squeezing around the legs are attached to this laminate.

Proposals for improving the water absorption performance of disposable diapers by making them thicker (or making the skin contact surface dryer) can be found in, for example, (a) Japanese Patent Publication No. 52-29657 and (b) Japanese Patent Publication No. 57-170.
It is disclosed in Publication No. 81.

In the former, loosely compacted cellulose fibers with higher water wettability are placed under the fibrous surface material,
Furthermore, a paper-like densified cellulose layer with relatively high wettability and high liquid retention is laminated below this, and finally a waterproof layer stops urine water. The latter, on the other hand, is a liquid-impermeable film (e.g. polyethylene film).
A large number of funnel-shaped openings with specific angles and small sizes are provided in the water absorbent body, and these are stacked so that the protrusions of the openings face the water absorbent body to prevent backflow.

Problems to be Solved by the Invention The disposable diaper having the configuration (a) above is designed to have a gradient in the apparent density and hydrophilicity of the fibers to promote the permeation and diffusion of urine water over the entire area of the water-absorbing material. The aim is to maximize the absolute water retention amount of urine to the water-absorbing material, resulting in a more hydrophobic surface material in a dry state. However, in this configuration, since the fibers are porous materials, water is retained between the fibers to varying degrees regardless of whether they are hydrophilic or hydrophobic. For this reason, the liquid held between the fibers rises against gravity due to capillary action, and when compressed, the liquid oozes out like a sponge, but these are physical phenomena and cannot be completely prevented. I can't.

In addition, the structure (b) allows free movement of fluid from the body into the absorbent material of the absorbent article by means of a funnel-shaped opening of a specific shape and size provided in the liquid-impermeable film. The purpose is to control the backflow of fluid from the absorbent material. However, when a funnel-shaped opening is provided in the liquid-impermeable film of the surface material, as in this configuration, the water permeation speed is not sufficient, which not only deteriorates the texture but also reduces softness and causes stuffiness. There were also problems with this.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a composite absorbent material whose main structure consists of a fibrous water-permeable surface material, crepe paper, a cotton-like bulb, a water-absorbing resin, etc. In a disposable diaper formed by sequentially laminating non-water-permeable thin film materials, a non-water-absorbing soft mesh made of synthetic resin is provided between each laminated member, at least between the fibrous water-permeable surface material and the composite water-absorbing material. The foam is inserted completely or partially.

The non-water absorbing soft mesh foam has a unit opening minimum width of 0.5
cm or more, the opening area is 0.2 to 30011, and the opening ratio is 30 to 90%, it exhibits excellent characteristics in preventing capillary action and backflow.

Furthermore, if the non-water-absorbing soft mesh foam is embossed with linear embossing at appropriate intervals on at least one side, the fit of the diaper to the body will be improved.

Function: The non-water-absorbing soft mesh foam inserted between the fibrous water-permeable surface material and the composite water-absorbing material acts as a kind of spacer and separates the surface material from the absorbent material, so that the water that permeates through the surface material The urinary water falls and is retained in the water-absorbing material, and backflow from the water-absorbing material to the surface material due to capillary action is prevented. Therefore, surface materials that come into direct contact with the skin tend to dry extremely easily, partly due to their excellent air permeability, and give a saree-like feel.

Example An embodiment of the present invention will be described based on the accompanying drawings.

A non-water-absorbing soft mesh foam 2 is inserted between the fibrous water-permeable surface material 1 that comes into contact with the skin and the composite water-absorbing material 3, at the center in the width direction and across almost the entire length direction. Then, on the lower side of the composite water-absorbing material 3, a non-water-permeable WI membrane 4 is laminated. At the upper and lower ends of the foam 2, the foam 2 and the composite water-absorbing material 3 are covered and bent along the non-water-permeable 111114. A water-impermeable thin film 4 is interposed between the surface material 1 and those members.
The same or different water-impermeable thin film 5 is inserted. 6 is a water-absorbing resin contained in the composite water-absorbing material 3. The non-water-permeable backing sheet 1114 has narrow rubber elastic bodies 7 fixed in the longitudinal direction at both left and right ends, and adhesive tapes 8 are appropriately attached to the left and right sides of the upper end.

The fibrous water-permeable surface material 1 refers to woven fabrics, knitted fabrics, non-woven fabrics, etc. made of polyester, polypropylene, cotton, rayon, etc., which are widely used in disposable diapers.
In terms of performance, it is desirable to have a material that is flexible, feels good on the skin, does not cause irritation to the skin, and has particularly good permeability for urine water and good drainage. For this reason, at present, as the surface material 1, a binder-free type made of long fiber nonwoven fabric of polyester or polypropylene and weighing 10 to 50 g1rd is generally used.

The non-water absorbing soft mesh foam 2 means that not only the synthetic resin itself but also the structure of the mesh foam itself is non-water absorbing, and there are no restrictions if the foam is a closed cell foam. However, in the case of an open-cell foam, the cells themselves may contain moisture, so the entire surface of the mesh foam must be a skinned foam covered with a water-impermeable membrane.

The composite water-absorbing material 3 refers to a general water-absorbing material made of crepe paper, cotton-like pulp, water-absorbing resin, etc., and does not limit the scope of the present invention in any way. The composite water-absorbing material 3 can use water-absorbing materials such as crepe paper, cotton-like pulp, and water-absorbing resin alone or in a mixed composite form, but generally cotton-like pulp is used above and below the water-absorbing resin 6. Further, a portion in which crepe paper is laminated above and below is placed in the main structural portion located in the center of the disposable diaper, and the water absorbent resin 6 corresponding to the auxiliary portion such as the side surface of the waist is often omitted.

The water-impermeable thin film 4.5 includes polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic ester,
A soft film made of synthetic rubber or the like with a thickness of 10 to 50 μm that does not allow water to pass through but allows water vapor to pass through is used.

In a disposable diaper, a band-shaped part with a width of 75 to 300 fl along the longitudinal centerline connecting the waist, crotch, and back forms the main structure, and the main structure is used for urination. Although most of the water is absorbed, the shape is not limited to that of the example.

The foam 2 includes synthetic resins such as polyethylene, ethylene-vinyl acetate, ethylene-acrylic acid ester, ethylene-propylene, ethylene-butene, ethylene-copolymer such as ethylene-vinyl chloride, soft vinyl chloride resin, polybutadiene, SBR, etc. A flexible foam made of a non-water-absorbing synthetic resin of rubber is used, and the mesh sheet of the foam 2 may be formed by direct extrusion, or by punching the extruded foam sheet in post-processing. It's okay.

Note that it is necessary for the mesh foam 2 to allow urine water to pass through it in a short time without any resistance, so that water is not retained in the mesh, so see Figures 2 and 3! The minimum unit width of the mesh indicated by , m is 0.5 cm or more, and the unit opening area (ixm) is 0.5 cm or more.
It is desirable that the opening ratio is in the range of 2 to 30% and the opening ratio to the entire area of the mesh foam 2 is in the range of 30 to 90%, and the shape of the openings may be modified as appropriate.

Minimum unit width of opening1. When m is less than 0.5 eta, the flow of urinary water becomes poor and the water is retained in a large number of openings, so that it becomes substantially the same as an open-cell material and gives the surface material 1 a crunchy feel. Can not. Moreover, when the unit opening area becomes 30 cd or more, the surface material 1 and the composite water-absorbing material 3 come into contact with each other due to the deflection of the fibrous surface material 1 and the pressure of the skin in contact with it, and an attempt is made to separate the two. The purpose of the reticulated foam 2 is no longer achieved. Furthermore, when the aperture ratio of the mesh foam 2 becomes 30% or less, the permeability of urine water becomes poor and the wet surface material 1 causes
Disposable diapers start to get stuffy. On the other hand, when the aperture ratio becomes 90% or more, it becomes impossible to provide the reticulated foam 2 with sufficient strength such as compression and tensile strength to maintain the space between the surface material 1 and the composite absorbent material 3.

The wall thickness of the mesh foam 2 is suitably in the range of 0.5 to 10 cm, particularly preferably in the range of 1.5 to 5 fl.
5 m or less, the mesh foam 2 loses its role as a spacer between the surface material 1 and the composite water absorbing material 3, and
When the length exceeds 0 m, the bending strength of the mesh foam 2 increases, and the disposable diaper not only becomes bulky during use, but also has a significantly poor fit to the body.

The mesh foam 2 may be inserted between the surface material 1 and the composite water absorbent material 3 over the entire surface, but to make it more functional, it may be inserted around the line connecting the abdomen, crotch, and back. It is inserted into a band-like body, and its shape may be arbitrarily changed according to the shape of the disposable diaper. In addition, if you want to improve the characteristics of the disposable diaper, by applying linear embossing (concave grooves) with an arbitrary cross-sectional shape on one or both sides of the mesh foam 2, it is possible to improve not only the flexibility of the foam 2 but also the laminated surface. The breathability and ease of urine flow can also be increased.

Furthermore, the lamination of the mesh foam 2 is performed by full or partial adhesion, and is selected in consideration of the overall functions such as touch, texture, and breathability when wearing the disposable diaper. .

Next, the effects of this embodiment will be explained.

When the paper diaper is attached to the user using the adhesive tape 8,
The discharged urine water is stopped by a relatively thin surface material 1 made of hydrophobic fibers, passes through the surface material 1 while diffusing in the planar direction, and is resisted from the opening area of each grass level of the mesh foam 2. The material constituting the foam 2 is non-water-absorbent, and each unit opening area is so thick that it cannot retain moisture (the surface area is significantly smaller than that of fibers). Therefore, there is very little moisture adhering to the surface.

The surface material 1 gives a soft touch to human skin, and is useful for surface air permeability and urine diffusion. On the other hand, the mesh foam 2 serves not only to prevent the backflow of urine but also to allow the air layer to move freely toward the surface material 1, thereby making the surface material 1 easier to dry. Moreover, the surface material 1 is mainly dried using body temperature, but since the surface material 1 is separated by the composite water-absorbing material 3 and the mesh foam 2 which is a heat insulating material, less energy is required for drying. .

Therefore, the disposable diaper of this embodiment exhibits a much superior drying effect using body temperature compared to the drying of conventional paper diapers in which the surface material 1 is in direct contact with the water-absorbing material 3.

Therefore, even after urinating, the surface material 1 of the disposable diaper is kept in a state where it is easy to dry and has good air permeability, so that the disposable diaper can be used up to the limit of the water retention capacity of the composite water absorbent material 3.

Next, the effects of this example will be shown for Comparative Example 1 and Example 1.

Comparative Example 1 A fibrous water-permeable surface material made of polypropylene nonwoven fabric with an apparent density of 0.5 g/cm2 and a wall thickness of 0.2 tlI, a composite water absorbing material with the following structure, and a white EVA (ethylene-vinyl acetate) with a wall thickness of 20 μm. A structure for a disposable diaper was formed by laminating three water-impermeable thin films (copolymer) film.

1st layer of composite water absorbent material 2nd layer of crepe paper of 14g/lri 3rd layer of cotton-like pulp of 300g/nf 4th layer of polyacrylic acid-based water-absorbing resin powder sprinkled with 100g/rrr 200g/ffr cotton-like pulp Pulp 5th layer 14
g/nf crepe paper Artificial urine (
NaC11.2%, KCl0.4%, (NHz)zC
When O0.2% aqueous solution) 50+1 was flowed down within 1 second, the surface material was still wet even after 1 minute.

Example 1 The following four types of mesh foams were prepared and inserted between the fibrous water-permeable surface material and the composite water-absorbing material of the disposable diaper structure of Comparative Example 1, and a similar test was conducted.

Reticulated foam sheet A is made of polyethylene closed cell foam with an apparent density of 0.034 g/aa, and has a skeleton with a wall thickness of 2W1L and a width of 5 cranes,
Reticulated foam B with an opening area of 15-square and an opening ratio of 56.3%.Appears to be made of EVA closed cell foam with a density of 0.034g/J, and has a skeleton with a wall thickness of 3+n and a width of 3fl. ,
Cross-linked ethylene-1 with an apparent density of 0.025 g/ad
It is made of 5-t% vinyl acetate copolymer, has a skeleton with a wall thickness of 3 squares and a width of 3 squares, has an opening area of 35 m square, has an opening ratio of 84.8%, and has a depth of 1 square inch. A crane with lattice-type embossing on both sides with 3w spacing D. Appears to have a density of 0.025g/cJ, a skeleton diameter of approximately 2 dragons,
Comparative Example 10 Comparative Example 10: Polyethylene net of open closed cell mixture having a skin with an open area ratio of 75% (extrusion gas foaming method)
When laminated between the surface material and the composite water-absorbing material, the same test as above was performed, and as a result, the surface material was saran and had better water drainage than in Comparative Example 1.

Effects of the Invention According to this invention, the non-water-absorbing soft mesh foam inserted between the fibrous water-permeable surface material and the composite water-absorbing material separates the surface material from the absorbent material and prevents the surface material from being absorbed by the absorbent material by capillary action. In addition to preventing moisture from flowing back into the surface material, it also reduces the amount of heat required to dry the surface material due to body temperature, so the surface material that comes into direct contact with the skin can be kept dry until the absorbent material maintains its maximum absorption capacity. This can give the user a smooth and pleasant feeling and prevent stuffiness from occurring.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway plan view showing an embodiment of the present invention;
Figure 2 is a sectional view taken along line ff-ff in Figure 1, and figure 3 is a cross-sectional view taken along line m-ff in Figure 1.
4 is a sectional view taken along line IV-IV in FIG. 1. DESCRIPTION OF SYMBOLS 1... Fibrous water-permeable surface material, 2... Non-water-absorbing soft mesh foam, 3... Composite water-absorbing material, 4... Water-impermeable thin film, 6... Water-absorbing resin applicant Sekisui Chemical Co., Ltd. Representative Hiroshi 1) Kaoru Figure 1 Figure 3 Figure 2

Claims (1)

[Claims] 1. The main structure includes a fibrous water-permeable surface material, crepe paper,
In a disposable diaper formed by sequentially laminating a composite water-absorbing material made of cotton-like pulp, water-absorbing resin, etc. and a water-impermeable thin film material, at least the fibrous water-permeable surface material and the composite water-absorbing material are stacked between each laminated member. 1. A disposable diaper characterized by having a non-water-absorbing soft mesh-like foam made of a synthetic resin inserted between the material and the material. 2. The non-water-absorbing soft mesh foam has a unit opening minimum width of 0.
．． The disposable diaper according to claim 1, which has a diameter of 5 cm or more, an opening area of 0.2 to 30 cm^2, and an opening ratio of 30 to 90%. 3. The disposable diaper according to claim 1 or 2, wherein the non-water-absorbing soft mesh foam has linear embossing on at least one side at appropriate intervals.