JPH0480701B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to absorbent articles such as sanitary napkins and disposable diapers, and more particularly to absorbent articles having a function of preventing leakage of human body secretions. [Prior Art] Conventionally, absorbent articles such as sanitary napkins and disposable diapers have been used in various ways to prevent human secretions such as menstrual blood and urine from leaking or seeping out of the absorbent articles. Efforts have been made. A technique is generally used in which a liquid-impermeable leak-proof sheet is provided on a portion of the lower surface or side surface and upper surface of the absorbent layer. Although this technique is somewhat effective, it cannot be said to be sufficiently effective against leakage from the sides, a phenomenon called lateral leakage. In order to increase the absorption capacity of the absorption layer, a technology was developed that applied water-absorbing polymers to the absorption layer, and the absorption capacity of the absorption layer itself was greatly improved. In addition, for sanitary napkins, adhesive napkins and the like have been developed for the purpose of fixing the napkin after being worn, and it has a sufficient fixing effect and has come to be able to considerably prevent side leakage due to misalignment of the napkin. However, these are only indirect measures, and more direct leakage prevention techniques are desired. As seen in Japanese Patent Publication No. 59-39134 and Japanese Patent Application Laid-Open No. 54-147695, there is a technique for preventing the diffusion of human body secretions between an absorbent layer, a liquid-permeable surface material, or both. However, these techniques are powerless against side leakage caused by diffusion within the surface material. Further, in Japanese Utility Model Application Publication No. 55-75317, etc., there is a technique of covering a part of the surface material with a water-impermeable sheet. In this case, when using an absorbent article, moisture generated by sweating from the skin remains on the non-water permeable sheet, causing not only stuffiness or discomfort to the user, but also rashes and inflammation. New problems arise, such as the risk of disease. [Problems to be Solved by the Invention] The main objective of the present invention is to prevent side leakage and seepage of absorbent articles. Side leakage of absorbent articles will be further explained using sanitary napkins as an example. Generally, as shown in Fig. 11a, a sanitary napkin has a leak-proofing material 2 covering the lower surface, side surfaces, and a part of the upper surface of an absorbent layer 3. Both are covered with a liquid-permeable surface material 1, and a part of the absorbent layer 3 is covered with a liquid-permeable surface material 1. It has a structure with a fastening tape 4 attached. When using sanitary napkins,
As shown in FIG. 11b, the center is formed into a chevron shape. Therefore, when the surface material 1 is a binder type that uses a conventional acrylic adhesive, the absorption speed is inferior, so the menstrual blood 5 is spread over the top surface of the surface material 1 from 5a to 5b as shown in FIG. 11b. It often flowed and caused side leakage. However, recently, surface materials that have a high absorption rate and reduced surface leakage have been developed by using polyolefin fibers as surface materials. As a result, menstrual blood 5 hardly flows on the surface of the surface material 1 as shown in FIG. 11b, and FIG.
As shown in the figure, the menstrual blood 5 was now well absorbed into the absorbent layer 3. However, if the menstrual blood retention capacity of the absorbent layer 3 is small or the menstrual blood propagation velocity is small, as shown in FIG. The surface material 1 has to absorb it again, and the menstrual blood 5a that is reabsorbed by the surface material spreads in various directions in the spaces between the fibers forming the surface material 1, preventing side leakage and oozing. It is the cause. Moreover, the worn napkin is not kept flat, and as shown in FIGS. 13a and 13b, many wrinkles occur on both sides of the long side, and grooves 6 are inevitably generated. Once formed, these grooves 6 do not return to their original planar shape; rather, when following changes in the shape of the crotch, the napkin folds at the grooves 6 and follows the changes, so the grooves 6 Nao tends to get bored. Therefore, menstrual blood also tends to leak from the groove 6, which is one of the causes of lateral leakage. These causes are due to differences in human body secretions such as menstrual blood, urine, and soft stools, and differences in the shape of the crotch between women and infants, as well as the accompanying mounting pressure.
This is common to sanitary napkins and disposable diapers. [Means for Solving the Problems] The present invention has been made in order to solve the above-mentioned problems. That is, the absorbent article of the present invention has an absorbent layer and a liquid-permeable surface material located above the absorbent layer, in which the liquid-permeable surface material located at least at both upper ends of the absorbent layer is made of hydrophobic fibers. The fibrous aggregate has voids between the fibers, and the fibrous aggregate and the surface material are integrated by welding the fibers at the points where they contact each other. . Hereinafter, the absorbent article of the present invention will be explained in detail using the drawings. FIGS. 1 and 2 show examples in which the absorbent article of the present invention is mainly applied to sanitary napkins. Of course,
This configuration can also be applied to disposable diapers. The lower surface, both side surfaces, and both ends of the upper surface of the absorbent layer 3 are covered with a leakage preventive material 2, and the entire surface material 1 is covered. A slip-preventing tape 4 is provided at the bottom layer. Fibrous aggregates 7 made of hydrophobic fibers are provided on the liquid-permeable surface material 1 located at both upper ends of the absorbent layer 3, and are integrated with the surface material 1 by welding the fibrous aggregates 7. . As is clear from FIG. 1, the fibrous aggregate 7 has many voids between the fibers. The liquid-permeable surface material that can be used in the present invention is not otherwise specified, but non-woven fabrics are preferred from the viewpoint of ease of acquisition, and non-woven fabrics can be made of either hydrophilic materials such as rayon or hydrophobic materials such as polyolefin. But it's okay. Moreover, the manufacturing method is not subject to any restrictions such as wet method, dry method, spunbond method, punching method, etc. The fibers that form the fibrous aggregate must be hydrophobic, and preferably thermoplastic or solvent-soluble to be suitable for the integration method described below. A wide variety of materials can be used, including ester, amide, vinyl acetate, and acrylic. Specifically, polyethylene, polypropylene, polyester, nylon, ethylene vinyl acetate copolymer, polyurethane, polybutadiene, high styrene, vinylidene, ethylene propylene rubber, acetate, etc., as long as the resin can be jetted from a nozzle and can form a fibrous aggregate. good. Among them, considering cost and processability, polyethylene, polypropylene, polyester,
Ethylene-vinyl acetate copolymer is recommended, as are polyurethane, polybutadiene, and ethylene-propylene rubber, which have elasticity and are less likely to wrinkle. The thickness of the fibers affects the size of the voids that occur between adjacent fibers, and the smaller the voids, the better, so thin fibers are preferable, and from the viewpoint of texture, 1 to 40 microns is preferable, and from the viewpoint of processability. 3 to 20 microns is more preferred. Furthermore, it does not prevent the use of water repellent treatment agents, clouding agents, pigments, etc. on the fibers. The amount of fibrous aggregates integrated into the liquid-permeable surface material is preferably 5 to 50 g/m ² because the larger the amount, the better the side leakage prevention effect. Furthermore, although the width of the fibrous aggregate is not limited in principle, it is preferably 5 mm or more in order to be more effective, and it is better for the width of one end to be 1/3 of the width of the sanitary napkin. It is desirable to have a large blood receiving area. As a method for integrating the liquid-permeable surface material and the fibrous aggregate, a melting method or a solvent method is preferable.
The melting method is a method in which a hot-melt resin is melted by heating it to a temperature higher than its melting point, and then sprayed onto a liquid-permeable surface material through a fine-hole nozzle. It solidifies and becomes integrated with the liquid-permeable surface material. The solvent method is a method in which a resin is dissolved with a solvent, then sprayed onto a liquid-permeable surface material with or without air as is commonly used, and then dried to remove the solvent.
By these methods, the liquid-permeable surface material and the fibrous aggregate are integrated. At this time, the solvent used may be any solvent as long as it dissolves the fibers constituting the fibrous aggregate, but tetrahydrofuran (THF), dimethylformamide (DMF), toluene, acetone, etc. ,
Hexane, ethyl acetate, etc. are recommended. Methods for integrating the liquid-permeable surface material and the fibrous aggregate may include, for example, a method using an adhesive or a method using heat embossing, but these methods are not suitable for the present invention because they do not have voids between the fibers. do not have. However, it cannot be prevented from using these methods together with the above-mentioned melting method or solvent method, but in this case, considering the voids between fibers and texture, the area where adhesive or heat embossing is applied should be 40% or less. It is desirable to do so. Another embodiment is shown in FIG. This embodiment is almost the same as FIG. 2, but differs in that the fibrous aggregate 7 is also provided on the side of the sanitary napkin. The embodiment shown in FIG. 4 is more effective in preventing side leakage. Still another embodiment is shown in FIGS. 5 and 6. Although these correspond to FIGS. 2 and 4, respectively, the fibrous aggregate 7 is also provided in the central portion forming the upper surface of the liquid-permeable surface material 1. The fibrous aggregate provided in the center is the liquid-permeable surface material 1
It is sufficient to impart hydrophobicity to the layer, but if it is too thick, it will impede liquid permeability, which is not preferable, and 3 to 5 g/m ²
is preferred. FIG. 7 shows an example in which the absorbent article of the present invention is mainly used as a disposable diaper. Of course, this configuration can also be applied to sanitary napkins.
In this configuration, a leak preventive material 2 that is wider than the bottom surface of the absorbent layer 3 is provided on the lower surface of the absorbent layer 3, and a liquid permeable surface material 1 is provided to cover the absorbent layer 3 and the leak preventer material 2. There is. A fixing tape or slip-preventing tape may be attached as necessary. Figures 8, 9, and 10 include Figures 4 and 5.
Fig. 6 shows an aspect corresponding to Fig. 6 . In FIGS. 10 and 8, the fibrous aggregate 7 is also provided on the liquid-permeable surface material 1 on the top of the leakage prevention material 2, but the fibrous aggregate in this part is omitted. is also possible. [Example] Next, Examples and Comparative Examples will be shown to help improve the understanding of the present invention. The following methods were used to measure liquid diffusivity and leakage prevention to confirm the effects of the present invention. (1) Diffusivity (applied mutatis mutandis to the wicking Klemm test method) Cut test pieces in which fibrous aggregates were integrated under various conditions into 15 cm widths in the width direction of actual napkins, and Immerse the considered part in horse defibrinated blood as a reference, and measure the suction distance after 10 minutes on the side that will be used (fibrous aggregate side). The result is better if the suction distance is short. (2) Leak-proofing property The base material of the test piece in which the fibrous aggregates were integrated under various conditions was 2 g of pulp, 1.2 g of absorbent paper, and 0.3 g of absorbent polymer as basic materials. A test napkin as shown in Figure 10 was produced as a prototype. Thereafter, as shown in Figure 3, the test napkin was set in a chevron shape (90°) similar to the actual wearing shape, and 10 c.c. of horse defibrinated blood was poured from the top of the napkin at a pressure of 50 g, which corresponds to the actual wearing pressure. The absorbent material was injected in two doses at 5 c.c./30 minutes under a pressure of 5 c.c./cm ² , and after 1 hour in this state, leakage from the side portions of the absorber was regarded as lateral leakage and the state of the lateral leakage was observed. Naturally, the result is that there is no side leakage. The test was performed on 10 points for each sample, and it shows how many of the 10 samples leaked horizontally.For example, 2/10 means that leakage occurred in 2 out of 10 samples. Dynamic human body model evaluation Using a leak-proof sample, a test sample 10 as shown in Fig. 15 was set on a movable female waist model 8 as shown in Fig. 14, and the tests were carried out 1 hour and 2 hours after starting. A total of 10 g of simulated blood, 5 g each, was injected twice from the simulated blood dripping tube 9, and for a total of 3 hours, the subjects were tested for a total of 3 hours with front and back leg opening (walking, directions D and D'), lateral leg opening, and leg closing (C and C). ’ direction) after repeating
Test sample 10 was checked for leakage. The test was performed on 10 points for each sample, and it shows how many of the 10 samples leaked laterally. Example 1 (Melting method) The various heat-melting resins shown in Table 1 were melted at a temperature higher than their melting points, and then sprayed with hot air at 300°C onto a preheated nonwoven fabric from a nozzle with a diameter of 0.3 mm to integrate the two. We created a surface material that Note that the fiber diameter was adjusted by changing the hot air volume and discharge pressure, and the fibrous aggregate weight was adjusted by changing the injection time. In addition, the nonwoven fabric is shown in Fig. 2, 4 to 6.
The figure uses Comparative Example No. 6 below, and Figs. 7 to 10 use No. 2. The evaluation results are shown in Table 1.

[Table] Example 2 (Solvent method) The various resins shown in Table 2 were dissolved in 9 times the weight of the solvent to create a 10% by weight solution, which was sprayed onto a nonwoven fabric with compressed air using a spray gun and dried. A surface material was obtained. Note that the fiber diameter was adjusted by changing the amount of air and discharge pressure, and the weight of the fibrous aggregate was adjusted by changing the injection time. Moreover, the same nonwoven fabric as in Example 1 was used. The evaluation results are shown in Table 2.

[Table] Comparative Example The same evaluation as in Example 1 or Example 2 was performed on various nonwoven fabrics in which fibrous aggregates were not integrated. The results are shown in Table 3.

[Action and effect]

Since the absorbent article of the present invention has the above-described structure, as shown in FIG. However, since the fibrous aggregates 7 are welded to the surface material 1, the diffusion of human secretions in the surface material is small, and since the fibrous aggregates 7 are hydrophobic, there is no leakage from there. , which has a great effect on preventing side leakage. In addition, since the fibrous aggregate has voids between the fibers, even though it is leak-proof against human body secretions, its breathability is not impaired, and it does not get stuffy during use, so it can be used comfortably. Furthermore, when the fibrous aggregate has elasticity, wrinkles are less likely to occur on the long sides during use, as shown in FIGS. 13a and 13b, and from this point of view, it is also excellent in preventing side leakage.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing one embodiment of the absorbent article of the present invention, FIG. 2 is a cross-sectional view taken along line X-X', FIG. 3 is a cross-sectional view showing its lateral leakage prevention mechanism, and FIG. 1
FIG. 0 is a schematic cross-sectional view showing another embodiment of the absorbent article of the present invention. Figure 11 shows an example of a conventional sanitary napkin, where a is a cross-sectional view showing the state before use, b is a cross-sectional model diagram of side leakage assuming the usage state, and Figure 12 is the surface material. This is an example of a conventional sanitary napkin that has been improved.
a is a cross-sectional model diagram of the absorption characteristics similar to FIG.
Figure 3 shows the state of the napkin when it is worn, with a being a side view and b being a plan view. FIG. 14 is a perspective view of a movable female waist model, and FIG. 15 is a view of the model with a test sample installed. Brief explanation of symbols, 1... Surface material, 2... Leak proof material, 3... Absorbent layer, 4... Anti-slip tape, 5...
...Blood, 5a...Blood that diffuses on the surface material or partially in the surface material, 5b...Blood that showed lateral leakage, 6...
...Groove on the side (long side) edge of the napkin, 7
... Fibrous aggregate, 8... Movable female waist model, 9... Tube for pseudo blood dripping, 10... Test sample.

Claims (1)

[Scope of Claims] 1. In an absorbent article having an absorbent layer and a liquid-permeable surface material located above the absorbent layer, at least the liquid-permeable surface material located at both upper ends of the absorbent layer is a fibrous material made of hydrophobic fibers. Absorbency characterized by being integrated with an aggregate, the fibrous aggregate having voids between the fibers, and the fibrous aggregate and the surface material being integrated by welding the fibers at the points where they contact each other. Goods.