JPH0533052B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to absorbent articles that are both absorbent and comfortable to use, particularly absorbent articles such as sanitary napkins and disposable diapers. [Prior Art] The basic structure of conventional absorbent articles, such as sanitary napkins and disposable diapers, is as shown in FIGS. 4 and 5.
An absorbent layer 3 made of cotton-like pulp, absorbent paper, water-absorbing polymer, etc., a leak-proofing material 2 made of a laminate sheet of polyethylene film and waterproof paper, a single polyethylene film, etc., and a sheet-like surface material covering the surface thereof. 4. Furthermore, it consists of a slip-preventing tape (fixing tape) to fix the installation location when using it. In particular, there are various performances required of these absorbent articles, but the most important are the inherent characteristics of good absorbency and little leakage.
Naturally, this is greatly influenced by the characteristics of the surface material that forms the surface of the absorbent article, so research has been conducted on the surface to improve the absorption characteristics of the surface material, that is, to increase the absorption rate, and various results have been reported. ing. For example, in an effort to improve the manufacturing method for surface materials, acrylic binders, or chemical binders, were traditionally used as adhesives, which lowered the absorption rate. A heat bond type using meltable fibers has been developed and is now widely used. Furthermore, in addition to the conventionally common rayon, hydrophobic fibers such as polypropylene, polyethylene/polypropylene composite fibers, polyester, polyamide, and polyacrylonitrile fibers are being considered as fibers to be used. In addition, as a relatively recent trend, the so-called spunbond method, in which a sheet-like material is adhesively formed in the form of long fibers, and the melt-blowing method, which can form ultrafine fibers as an applied method, have been developed as nonwoven fabric manufacturing methods. , its use in absorbent articles is also seen. Furthermore, in order to improve the absorption capacity of the absorbent layer in order to prevent leakage due to insufficient absorption capacity, highly absorbent polymers such as acrylic acid-based and starch-based graft polymers are actively used. the result,
It is considered that the absorption capacity of the absorption layer itself has improved, and leakage due to insufficient capacity has been greatly reduced. However, this also requires measures to prevent leakage of the surface material, that is, how to effectively guide menstrual blood or urine to the absorbent layer.
This means that the above points are important. Therefore, if we consider the surface material once again, including its form, in any case, the surface material in conventional configurations is preformed as a sheet-like material, which can be laminated, folded, and fixed to obtain an absorbent article. is the conventional technology. [Problems to be solved by the invention] Looking at the actual absorption state of absorbent articles,
When evaluating the surface material itself, it was found that leakage occurs even in the case of sanitary napkins, for example, which are composed of a surface material with a high absorption rate and an absorbent layer with sufficient absorption capacity. The inventors of the present invention conducted a detailed analysis of the cause, and found that the absorbent layer is set in the shape of the crotch for several hours due to the movement of the groin during use, such as when walking. So-called wobbling of the absorption layer occurs. On the other hand, the surface material does not behave integrally in the form of a covering sheet, and for this reason, whereas the surface material and the absorbent layer should originally be stacked and adjacent to each other, the surface material 4 and the absorbent layer are stacked together as shown in FIG. A space X is created between 3. As a result, menstrual blood excreted onto the surface material 4 is not effectively guided to the absorbent layer 3, and the surface material 4
It will stay in. Then, the original surface material 4
Since it has a basis weight of about 20 g/m ² and a small absorption capacity, it is impossible to absorb and retain it, and as shown in FIG. This will cause leakage. In other words, it is important as a measure to prevent leakage that the absorbent layer 3 and the surface material 4 are always kept in an integrated state despite the complicated shape and movement of the crotch. This is a thick type surface material (for example, a type with weak adhesive on the back side) that is effective as a means to prevent stickiness during use (return of absorbed liquid to the surface), which is also required for absorbent articles. In this case, it becomes necessary to further fix the absorbent layer and the surface material.
One way to do this is to fix the surface material and absorbent layer from the use side using a heat roll or glue, but it is not possible to completely prevent the generation of hot melts and solids from the glue. This is not possible and leads to a poor usability. Furthermore, since it is an absorbing surface, it is not possible to secure a sufficient fixed surface, so it does not exhibit an integrated behavior with respect to the movement of the complex shape described above, and is not an essential solution. Furthermore, if the amount of menstrual blood is small, the surface material should be selected taking into consideration texture rather than absorbency. In other words, specifically, thin fiber diameter and low basis weight are good,
Such nonwoven fabrics have low strength and elongate significantly under low loads, and when processed in actual napkin forming machines, their processing suitability is significantly reduced, making them unusable and not currently used. As described above, in the conventional technology, no measures have been found to effectively prevent leakage when the movement during use is taken into consideration. A similar phenomenon was also found in disposable diapers. [Means for Solving the Problems] In order to eliminate the drawbacks of such conventional absorbent articles, the inventors of the present invention have developed an absorbent article that has absorbent properties, particularly to prevent leakage, and at the same time provides an excellent feeling of use during use. As a result of intensive research to find sex products,
This led to the present invention. That is, the present invention provides an absorbent article having an absorbent layer and a surface material covering the surface of the absorbent article, in which the surface material is composed of a fibrous aggregate integrated with the absorbent layer, and the fibrous aggregate covers the surface of the absorbent layer. On the other hand, it is formed by discharging a hot-melt resin in a molten state through micropores, or by discharging it from a nozzle by high-pressure spray after making it into a solvent solution, and the fibrous aggregate has spaces between the fibers, The present invention relates to an absorbent article characterized in that the absorbent article is integrated with the absorbent layer by welding fibers at the portions in contact with the absorbent layer. Hereinafter, the absorbent article of the present invention will be explained in detail using the drawings. FIG. 1 is a cross-sectional view showing an embodiment of the absorbent article of the present invention, and FIG. 2 is an enlarged view of section B thereof. The fibrous aggregate 1 according to the present invention is integrated by welding the fibers at the portions 5 in contact with the absorbent layer 3, and is not melted by heat or fixed with a glue such as a chemical binder as in the past. Absorbency and usability are not impaired. The method for integrating the fibrous aggregate onto the surface of the absorbent layer is as follows:
This can be carried out either by discharging the thermofusible resin in a molten state through fine holes, or, for resins soluble in a solvent, by making a solvent solution and then discharging it from a nozzle using high-pressure spray. The melting method involves melting the resin above its melting point, and it is usually 100 to 500μ.
Air at 200~400℃ is injected onto the absorption layer from multiple nozzles with 200μ micropores. The injected system is elongated and thin. In the solvent method, the resin is dissolved with a solvent and then sprayed with or without air, which is commonly used, and then dried. Any solvent may be used as long as it dissolves the resin, but tetrahydrofuran, toluene, and dimethylformamide are preferable from the viewpoint of workability. Further, the fibers forming the fibrous aggregate of the present invention include polyethylene, polypropylene, ethylene-vinyl acetate copolymer (EVA), polyester,
Basically, polymeric substances such as polyurethane, polybutadiene, and modified products thereof that can be discharged from micropores by various means can be used, and the material can be selected depending on the intended use and designed performance. Moreover, the component is not limited to a single component. Further, the formation of the fibrous aggregate is not limited to a single layer, but may be formed in multiple layers in view of the required performance, texture, etc. In addition, there are no particular restrictions on the fiber diameter, density, or weight to be formed, but the fiber diameter is 1
-40μ is preferred, and 3-20μ is more preferred. In particular, in order to improve the texture, it is effective to make the outermost layer (or itself if it is a single layer) have a smaller fiber diameter. In addition, to improve the absorption characteristics for highly viscous materials, lower the fiber density (larger the space between fibers),
It is better to form a collective. Furthermore, there are no restrictions on the application of surfactants, coloring materials, embossing, etc., if necessary. Furthermore, there are no restrictions on the materials and configurations of the absorbent layer, leakage preventive material, etc. of the applied absorbent article. In other words, an absorbent article in which a fibrous aggregate as a surface material is integrated on the surface of an absorbent layer in this way,
As mentioned above, there is no separation between the surface material and the absorbent layer during use, which is seen in conventional absorbent articles, and as shown in Figure 3, the absorbent layer is always on the surface of the absorbent layer to effectively absorb menstrual blood. Since the fibrous aggregate 1 is arranged so that the function of guiding the body is not impaired, it is possible to significantly prevent leakage during use, especially during active activities. [Example] Hereinafter, the present invention will be explained in more detail with reference to Examples. Table 1 shows the fibrous aggregates of the present invention used in Examples and, as a comparative example, a single sheet obtained in the form of a nonwoven fabric under the same conditions without being integrated with the surface of an absorbent layer. Additionally, Table 2 shows surface materials obtained by general methods used as comparative examples.

【table】

[Table] The sample code for the sheet formed under the following conditions is as follows:
Add 〓′〓.

【table】

[Table] Example 1 Application: Regular type sanitary napkin An absorbent layer consisting of cotton pulp (2.5g), 4 sheets of absorbent paper (2g), water-absorbing polymer (0.3g), and waterproof paper laminated with 8μ polyethylene. It was laminated as a leakage preventive material and used as a basic structure. In the product of the present invention, a fibrous aggregate was formed on the use side of the above structure. Comparative examples were also prepared by covering the same structure with various sheet-like surface materials. In addition, tape was installed on unused surfaces to prevent slippage. This test sample was evaluated for leakage rate, separation state, and texture using the following methods. The results are shown in Table-3. <Test method> As shown in Fig. 7, movable female waist model 6
Then, as shown in FIG. 8, test sample 8 was set, and 5 g of simulated blood was added twice in total from tube 7 for dripping simulated blood 1 hour and 2 hours after starting.
A total of 10g was injected, and for a total of 3 hours the patient was able to do front and back leg splits (walking,
After repeating lateral leg opening and closing (directions C and C'), test sample 8 was checked for leakage. The state of separation between the surface material and the absorbent layer at that time was also checked. Further, the test was conducted five times for each sample. In addition, the texture of the surface to be used was evaluated by the overall average evaluation of a sensory test conducted by five women. The evaluation stage is 5 points for very good texture, 4 points for good texture, and 3 points for average texture.
The scores were given as 2 points for poor texture and 1 point for very poor texture, and the average score was taken as the average score of the 5 people.

【table】

[Table] From Table 3, it can be seen that the absorbent article of the present invention exhibits a superior leakage prevention effect compared to the comparative example. The effect is exhibited almost unaffected by the type of base material (resin), fibrous aggregate method, average fiber diameter, and basis weight. This shows how the integration of the surface material and the absorbent layer greatly contributes to the leakage prevention effect, and samples with a separation distance of 2 mm or more were found under the same conditions as the present invention. It was made into a sheet with
It includes E′, J′, O′, T′, and V′, all of which have a high leakage rate. In other words, this demonstrates the usefulness of the present invention compared to conventional absorbent articles coated with sheet-like surface materials. In addition, in terms of texture, U, which has a thin fiber diameter of 9μ, has received particularly high praise. In addition, overall, some products were rated higher than the comparative examples, and it was confirmed that the materials had the texture of other surface materials that were developed with emphasis on the current texture. . Example 2 Application: Sanitary napkin for long-term use Waterproof paper laminated with absorbent layer consisting of cotton pulp (4g), 4 sheets of absorbent paper (2g), and water-absorbing polymer (0.5g) and polyethylene 8μ as leak-proof material. Laminated layers were used as the basic structure. A test sample was then prepared in the same manner as in Example 1. The test method was the same as in Example 1, except that the simulated blood was dropped at 5 g every hour for a total of 20 g four times. The results are shown in Table 4. As with Example 1, the results showed that the absorbent article of the present invention had an excellent leakage prevention effect. In addition, as described in Example 1, in order to improve the texture on the use side, structural control was performed by changing the two types of resin or the fiber diameter in the thickness direction of the fibrous aggregate. It was also confirmed that there was no effect on absorption characteristics.

[Table] Example 3 Application: Paper diaper Absorbent layer consisting of cotton pulp (30g), absorbent paper (5g), and water-absorbing polymer (3g), back sheet,
A paper diaper was constructed using fixing tape as the basic constituent material, and a test sample was prepared. Then, a practical test was conducted using five test samples each to check for leakage after use and the shape retention of the surface material and absorbent layer. The results are shown in Table-5. As is clear from this, in absorbent articles used under complex movements as in the case of the sanitary napkins of Examples 1 and 2, the surface material is integrated into the absorbent layer of the present invention. This usefulness was also confirmed in the paper diaper of this example.

【table】 [Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an embodiment of the absorbent article of the present invention before use, FIG. 2 is an enlarged view of part B thereof,
Fig. 3 is a cross-sectional view of the sanitary napkin in use, Fig. 4 is a perspective view showing an example of a conventional sanitary napkin, Fig. 5 is a cross-sectional view taken along line A-A', and Fig. 6 is a cross-sectional view of the sanitary napkin in use. Figure 7 is a perspective view of a movable female waist model;
FIG. 8 shows a test sample installed in the model. 1... Fibrous aggregate, 2... Leak proof material, 3... Absorbent layer, 4... Sheet-like surface material, 5... Adhesion (anchor) portion of fibrous aggregate to absorbent layer, 6... Movable female waist model, 7... tube for pseudo blood dripping, 8... test sample.

Claims (1)

[Claims] 1. In an absorbent article having an absorbent layer and a surface material covering the surface of the absorbent article, the surface material consists of a fibrous aggregate integrated with the absorbent layer, and the fibrous aggregate is thermally melted to the surface of the absorbent layer. The fibrous aggregate is formed by discharging a molten resin through micropores, or by discharging it from a nozzle using high-pressure spray after making it into a solvent solution.
1. An absorbent article characterized in that the absorbent article is integrated with the absorbent layer by welding fibers at the portions in contact with the absorbent layer.