JPH044899B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to sanitary napkins, disposable diapers,
The present invention relates to a method for producing a surface material for absorbent articles such as incontinence pads. (Prior Art) Fibrous nonwoven fabrics have conventionally been generally used as surface materials for absorbent articles. Various methods are known to improve the permeability of this surface material to body fluids, one of which involves providing a large number of pores. The following methods are known as means or methods for providing this opening. (1) The surface material is formed using a known paper or nonwoven fabric manufacturing method, and then punched with a punching cutter to provide holes. This is an extremely simple method for providing holes, but since the fibers are pushed through,
There are many cut ends at the edges of the aperture area, which feel bad when they come into contact with the skin, and also reduce the tensile and tearing strength of the surface material, and cause fibers to become frayed or fluffed from the edge of the aperture area. or (2) Perforations are provided during or after forming the surface material using a known paper or nonwoven fabric manufacturing method, by applying a jet of water to push or scrape the fibers and distribute them. This does not have the disadvantage of (1) above because the fibers are distributed, but some fibers are present in the aperture area or at the edges and complete pores are not formed. In particular, hydrophobic fibers are preferred as constituent materials for this type of surface material, but if these fibers remain in the pore areas or at the edges, the desired body fluid permeability cannot be achieved. . (3) After forming the surface material using a known nonwoven fabric manufacturing method, pores are added by pressing it with a heated embossing roll and melting the fibers. This is because the edge of the aperture area is pressed and melted, and a film is formed by welding the fibers on the edge, and the film is partially torn, resulting in
Complete pores are not formed as in (2) above. (Problems to be Solved by the Invention) The above-mentioned known technology not only has the above-mentioned drawbacks, but also does not leave a moist feeling on the surface of the surface material after body fluids have permeated therethrough, that is, it does not feel dry to the skin. No particular consideration or creation has been made to provide dry touch properties or to prevent body fluids from returning (rewetting) by applying pressure to the surface material after body fluids have permeated therethrough. In addition to the above-mentioned two properties, i.e., dry touch properties and anti-rewet properties, the properties required for this type of surface material include quick permeability of body fluids and good texture. Furthermore, although these performances are contradictory to each other, the above-mentioned known technology has not been able to satisfy these performances at the same time by adjusting or controlling them well. (Means for Solving the Problems) An object of the present invention is to provide a method for manufacturing a surface material for an absorbent article that can simultaneously satisfy each of the above-mentioned performances. The present invention for achieving this object will be described below based on illustrated examples. As shown in FIGS. 1 to 3, the surface material 1
has a large number of openings 2. In order to achieve the intended purpose of the present invention, the surface material 1 is made of heat-melting hydrophobic fibers, the fibers are 10μ or less, and the basis weight is 10.
g/m ² or more, the total area ratio of each opening 2 in the surface material 1 is 10 to 50%, and the shortest diameter is 0.3 to 2 g
The water pressure resistance of non-porous area 3 is ``JIS-L1092
Measured value according to water resistance method A (low water pressure method)
It is 10g or more. If the diameter of the pores 2 is 0.3g or less and the porosity is 10% or less, the permeability of body fluids, especially the rate, will decrease significantly, and if the diameter is 2g or more and the porosity is 50% or more, More body fluid flows out from the opening 2. If the fiber diameter is 10 μ or more and the basis weight is 10 g/m ² or less, even if all the constituent fibers are hydrophobic, a relatively large amount of space will be created between the fibers, so the amount of body fluid remaining in the non-porous area 3 will decrease. If the water pressure resistance is less than 10g, the non-porous area 3 will be impregnated with body fluids or the body fluids will be absorbed into the area due to pressurization during use. flows backwards, and dry touch properties cannot be obtained as above. Note that the basis weight may be 10 g/m ² or more, and there is no upper limit from the viewpoint of performance, but from the viewpoint of cost it should be 5060 g/m ² or less. As the heat-melting hydrophobic fiber, polyester, polypropylene, polyethylene, etc. may be used alone or in a mixture of appropriate amounts thereof. The surface material 1 is made of fibers with a diameter of
If the surface weight is 10 μ or less and the basis weight is 10 g/m ² or more, the water pressure resistance will be 10 g or more, but in order to further improve the water pressure resistance, the entire surface material 1 may be treated to be water repellent. The water repellent is not particularly limited, but in view of non-irritation to the skin, water repellent effect, etc., known silicone-based agents are preferred. Furthermore, in order to achieve the intended object of the invention, the facing material 1 should be free of fibers in the area of the apertures 2;
and that the fibers at the edges of the region are fused, that is, the pores are substantially complete, regardless of the shape of the pores, such as circular, elliptical, square, or any irregular shape thereof. It is preferable that it is formed. If the apertures 2 are not formed in this manner, the fibers present within the aperture region or at the edges are hydrophobic, which would impede the permeability of body fluids in that region. A typical example of fibers existing at the edge of the aperture 2 is that the fibers exist as fluff at the edge, but even if the fluff is extremely small, the fluff lifts body fluid droplets. This prevents the body fluid droplets from coming into contact with the absorbent body disposed on the lower surface of the surface material 1, and as a result, the transferability of the fluid to the absorbent body deteriorates. The surface material 1 can be manufactured by the following method. As illustrated in FIGS. 4A and 4B, a fiber web formed by a card is used as a support 5 having aperture-forming elements 4 consisting of a large number of protrusions, through holes, or recesses.
In the above process, the fibers are entangled to form a non-woven fabric by a high-speed water jet treatment, and at the same time, the fibers are distributed by the aperture forming element 4 to form the apertures 2. As a method of forming the openings 2 at the same time as forming a non-woven fabric in this way, for example, Japanese Patent Publication No. 49-28023 and Japanese Patent Application Laid-open No. 51-7
No. 82072, No. 51-105480, No. 53-114874, No.
58-132155 and the like can be used. The support 5 may be a roll or a curved plate as in the illustrated example, or may be a belt. Generally, when the apertures 2 thus formed are observed with the naked eye, the presence of fiber fuzz within the area or at the edges is not clearly visible, but when observed with a magnifying lens or a microscope, the apertures 2 are not necessarily completely formed. However, fine fiber fuzz is present within the area of the aperture 2, particularly at the edge of the area (see FIG. 5). Accordingly, in the present invention, complete apertures 2 are formed by burning the surface material 1 with flame to melt or burn off the fiber fuzz within the area of the apertures 2. This searing treatment is preferably carried out in a state where the fiber web or the surface material 1 contains sprayed water. In this case, since the fiber web or surface material 1 contains water, only the fiber fuzz can be easily and completely melted or burned off without any adverse effects of heat on the entire fiber web or surface material 1. However, the present invention does not exclude or prohibit the roasting treatment to be carried out while the fiber web or surface material 1 is in a dry state. A product that achieves the desired purpose can be obtained regardless of the following order of fiber entanglement, hole opening, and roasting in the above manufacturing method. A: Entanglement of a fiber web by jetting high-speed water onto a support having an aperture-forming element, formation of apertures → drying of the web → roasting of the web. B. Entanglement of a fibrous web by jetting high-speed water onto a support having an aperture-forming element, formation of apertures→searing treatment of the web→drying of the web. C. Entanglement of the fiber web and formation of apertures on a support having an aperture-forming element by jetting a high-speed water stream→roasting the web on the support→returning the web onto the support by spraying the web again. Entanglement → drying of the web. D. Entanglement of the fiber web by jetting high-speed water jets on a support having an aperture-forming element, and formation of apertures → Roasting treatment of the web on the support → Again on a support without the aperture-forming element Entanglement of the web by the jetting→roast treatment of the web→drying of the web. E Entanglement of the fiber web by spraying a high-speed water jet on a support having an aperture-forming element, and formation of apertures → Entanglement of the web by the spray again on a support without the aperture-forming element → Entanglement of the web Grilling →
Drying the web. F Formation of pores in the fiber web by jetting high-speed water jets on a support having pore-forming elements → Roasting the web on the support → By spraying on a support without pore-forming elements Entanglement of the web → drying of the web. In the cases of C, D, and E, the reason why the high-speed water jet is jetted again is to further improve the strength of fiber entanglement. Note that the surface material 1, which is a perforated nonwoven fabric obtained by the method of the present invention, may have a fibrous layer made of hydrophilic fibers on the back surface of the surface material 1, preferably a nonwoven fabric whose fibers are entangled by jetting the high-speed water jet, or a fused fabric, depending on the purpose of use. A nonwoven fabric whose fibers are bonded by bonding may be integrally composited. This joining can be accomplished by either fiber entanglement by jetting the high-speed water jet or fiber bonding by fusion. The surface material 1 having the above-mentioned configuration is used for absorbent articles such as sanitary napkins, disposable diapers, and incontinence pads, as illustrated in FIG. It is constructed by placing an absorbent material 6 such as pulp or water-absorbing paper on at least the upper surface and a water-impermeable sheet 7 such as a plastic film on the lower surface, and the other specific construction is a known article of this kind. This is done by the means disclosed in . Incidentally, in the case of a composite in which a hydrophilic fiber layer is integrally formed on the back surface of the surface material 1, it goes without saying that the fiber layer is located between the surface material 1 and the upper surface of the absorbent body 6. do not have. As shown in FIG. 3, when body fluid is excreted into a certain surface area of the surface material 1 when the surface material 1 is used in an absorbent article, the absorbent body 6 is discharged from each opening 2 in the surface area. However, since the fibers at the edges of each aperture 2 are melted and are substantially intact, the body fluid can be absorbed quickly into the absorbent body.
In addition, the absorbed body fluid can be absorbed by ensuring that the fibers in the non-porous area 3 forming the surface material 1 are hydrophobic, have a fiber diameter of 10 μ or less, have a basis weight of 10 g/m ² or more, and have the shortest diameter of the pores 2.
Since it weighs 0.3 to 2 g and has a porosity of 10 to 50%, it will not return from the surface material. Further, although the non-perforated region 3 is made of very thin fibers and has a relatively high density, it is made up of a collection of fibers and therefore has air permeability. (Example) As shown in Table 1. However, in Examples 1 to 7 in Table 1, the surface material (sixth
(see figure) was manufactured. Table 2 shows the performance of the examples shown in Table 1 and the performance of the comparative example. Comparative Example 1 is a surface material used by the present applicant for disposable diapers, which consists of 50% by weight of rayon fibers of 1.5d x 5g and 50% by weight of polyester fibers of 1.4d x 44g. It is a non-woven fabric with a size of 2 m ² and is formed by intertwining the fibers with a jet treatment of high-speed water. Comparative Example 2 is a surface material used by Company A for disposable diapers, which is made of a 25 g/m ² polyethylene film and has a large number of holes of 0.5 gφ and 1 g intervals, and its porosity is is 20%. The performance shown in Table 2 was based on the following test method. (1) Permeability A sample (surface material) is placed on the top of an absorbent made of cotton-like wood pulp, and 5 ml of artificial urine in a beaker is poured over it at once, and the seconds required for it to completely penetrate the sample are measured. The number was measured. (2) Rewetting property A sample is placed on the top surface of an absorbent body made of 100 g of cotton-like wood pulp, and after pouring 5 times the weight of Biuret artificial urine on top of the sample, a rubbery artificial urine is placed on top of the sample. Layer the skin sheets, and then apply 100g and 7g flat plate weights on top.
After 3 minutes, the weight was removed and the amount of artificial urine adhering to the artificial skin sheet was measured. (3) Dry touch property After the above-mentioned rewet measurement, the sample was touched with the palm of the hand to test the degree of wetness.

【table】

[Table] (Effects of the invention) According to the manufacturing method of the surface material of the present invention, a surface that simultaneously satisfies contradictory properties such as quick permeability of body fluids, dry touch properties, anti-rewet properties, and texture, as well as breathability. In addition, since the edges of the openings that serve as the guide portions for body fluid permeation are formed by melting, the fibers do not become frayed, fluffed, or damaged from the edges of the openings. A surface material whose overall strength is always maintained can be obtained. Furthermore, a surface material having the above performance can be produced relatively easily and industrially stably.

[Brief explanation of drawings]

FIG. 1 is a partial perspective view of the surface material produced by the manufacturing method of the present invention, FIG. 2 is a partial sectional view of FIG. 1, FIG. 3 is a partial sectional view of the surface material applied as an absorbent article, and FIG. 4A and 4B are partial perspective views showing the support used when the surface material is formed by a high-speed water jet spraying process, and FIG. A photograph substituted for a drawing showing a partial enlarged plane of the texture of the fiber nonwoven fabric, which is the surface material in a state where it has not been completely roasted, and Figure 6 is a photograph showing the surface material, which is the surface material, after the openings in Figure 5 have been roasted. A photograph substituted for a drawing showing a partially enlarged plane of the tissue. DESCRIPTION OF SYMBOLS 1... Surface material, 2... Opening, 3... Non-opening area, 4... Opening forming element, 5... Support body.

Claims (1)

[Scope of Claims] 1. A method for producing a surface material made of a nonwoven fabric having a large number of holes for use in absorbent articles, wherein the surface material is a heat-resistant material having a fiber diameter of 10 μ or less and a basis weight of 10 g/m ² or more. Using a molten hydrophobic fiber web, the fiber web is sprayed with a high-speed water jet to entangle the fibers and distribute the fibers, resulting in a porosity of 10.
-50% and a step of providing apertures with a shortest diameter of 0.3 to 2 g, and a step of melting or burning out the fibers remaining in the aperture area by burning the fiber web with a flame. A method for producing the surface material, comprising: 2. The method for producing a surface material for an absorbent article according to claim 1, wherein the roasting treatment is performed while the fiber web is in a wet state. 3. The method for producing a surface material for an absorbent article according to claim 1, wherein the fiber entanglement and the provision of apertures are performed on a support having aperture forming elements arranged at predetermined intervals. 4. The method for producing a surface material for an absorbent article according to claim 3, wherein the roasting treatment is performed on the support during the steps of fiber entanglement and opening. 5. The method for producing a surface material for an absorbent article according to claim 4, wherein after the roasting treatment, the spraying treatment is performed again on the support. 6. The method for producing a surface material for an absorbent article according to claim 1, wherein the surface material is formed by fiber entanglement.