JPH0572220B2 - - Google Patents

Description

[Detailed description of the invention]

(1) Purpose of the invention [Industrial field of application] The present invention relates to a top sheet of an absorbent article and a method for manufacturing the same. More specifically, the present invention relates to a top sheet for disposable absorbent articles such as sanitary napkins, disposable diapers, and incontinence pads, which forms the surface that comes into contact with the user's skin, and a method for manufacturing the same. [Prior Art] In general, this type of surface sheet allows body fluids to quickly permeate into the interior of the article without oozing or remaining on the surface of the article; This reduces the possibility that water flows back to the surface due to the user's body pressure and wets the user's skin, and also improves elastic compression recovery rate, texture (feel),
Performance such as preventing fluffing and improving tensile strength is desired. Conventionally, in order to impart some of these performances to a topsheet, the topsheet is composed of a front 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, each having a predetermined fiber weight ratio, and In order to arrange comparatively fine denier fibers on the back layer and relatively thick denier fibers on the back layer, and to fuse the fibers of the front and back layers, for example, polypropylene-polyethylene core-sheath composite fibers, usually polyester -Techniques for incorporating core-sheath type composite fibers of low melting point polyester were disclosed in Japanese Patent Publication No. 59-39136 and Japanese Patent Application Laid-open No. 61
-2854 and JP-A No. 61-31155. Also, in Japanese Patent Application Laid-open No. 61-31155,
The inclusion of crimped fibers is also disclosed. [Problems to be Solved by the Invention] The surface sheet according to the known technique described above does not satisfy the above performance. In particular, since the fibers are simply fused at fiber intersections, the fused area is small, the tensile strength is low, and the fibers are easily damaged. Furthermore, in the technique of using core-sheath composite fibers of polypropylene-polyethylene as the fused fibers, processing operations under heating are relatively difficult because the difference in melting point of the components is small. Further, in the technique of using a core-sheath composite fiber of polyester and low melting point polyester as the fusion fiber, there is a problem that the feel is not good because polyester is harder than polyethylene. The first object of the present invention is to provide a top sheet for sanitary articles that can satisfy the above-mentioned performance, particularly a top sheet that has a large fused area at fiber intersections, has high tensile strength, and is difficult to break. do. A second aspect of the present invention provides a method for producing the top sheet according to the first aspect of the present invention, in particular, the heating treatment of the fiber web is relatively easy, and the strength of the constituent fibers of the web is reduced by the heating treatment. The main purpose is to provide a manufacturing method that does not cause deterioration in performance. (2) Structure of the Invention [Means for Solving Problems] The first gist of the present invention is that the present invention contains at least 65% by weight of 1.5 to 3 denier fibers that are polyester-polyethylene core-sheath type composite fibers. A top sheet of an absorbent article made of a fiber web, wherein the fibers of the web are fused by the polyethylene at the intersections of the fibers of the web, and the polyethylene partially distributed at the intersections. The top sheet is characterized in that the top sheet is fused together. The first and most preferred embodiment of the present invention is comprised of 80-100% by weight of a first fiber of 1.5-3 denier which is a core-sheath composite of polyester-polyethylene and 0-20% by weight of other second fibers. Naru 7~
15 g/m ² surface layer fiber web and the first fiber 60~
a 15-23 g/m2 backing fiber web consisting of 80% by weight and 20-40% by weight of a crimped third fiber of 2-6 denier which is a side-by ^- side composite of polyester-high shrinkage polyester; are laminated, and the fibers of the web are fused by the polyethylene of the first fibers at the intersections of the fibers of the web, and are also fused by the polyethylene partially unevenly distributed at the intersections. A surface sheet may be mentioned. The second gist of the present invention is to heat-treat a fiber web containing at least 65% by weight of fibers of 1.5 to 3 denier, which are polyester-polyethylene core-sheath type composites, so that the fibers of the fibers of the web are The fibers of the web are fused by the polyethylene, and at least a portion of the polyethylene is flowed and unevenly distributed at the intersection, and the fibers of the web are also fused by the unevenly distributed polyethylene. The present invention resides in a method for manufacturing a top sheet of an absorbent article. The second most preferred embodiment of the present invention comprises 80-100% by weight of a first fiber of 1.5-3 denier which is a core-sheath composite of polyester-polyethylene and 0-20% by weight of another second fiber. Naru 7~
15g/ ^m2 surface fiber web and the first fiber 60~
80% by weight and a side-by-side composite of polyester - high shrinkage polyester -
15 consisting of 20-40% by weight of 6 denier tertiary fibers
~23 g/m ² of a back layer fiber web and heat treating the web to fuse the fibers of the web by the polyethylene of the first fibers at least at the intersections of the fibers of the web,
At least a portion of the polyethylene of the first fibers is flowed and unevenly distributed at the intersection point, and the fibers of the web are also fused by the unevenly distributed polyethylene of the first fibers, and the fibers of the web are crimped. The method for manufacturing a topsheet according to claim 9, which expresses the following. Note that other embodiments of the first and second aspects of the present invention will become clear from the description below. Hereinafter, embodiments of the present invention will be described with reference to the drawings, and for the sake of brevity and convenience, the first and second embodiments will be described together. Referring to FIG. 1, the top sheet 1 is composed of a surface fiber web 2 of 7 to 15 g/m ² that is in contact with the user's skin and a back fiber web 3 of 15 to 23 g/m ² that is not in contact with the user's skin. ing. The surface fiber web 2 has a second
The first fiber of 1.5 to 3 denier is a core-sheath type composite of polyester 4a-polyethylene 4b as shown in the figure.
It is composed of 80 to 100% by weight and other secondary fibers. The back layer fiber web 3 contains 60 to 80% by weight of the first fibers and the polyester 5a shown in FIG.
It is a side-by-side type composite of highly shrinkable polyester 5b by heat, and is composed of 20 to 40% by weight of crimped third fibers of 2 to 6 deniers. If the surface fiber web 2 is less than 7 g/m ² and the back fiber web 3 is less than 15 g/m ² , the required strength will not be achieved and body fluids will rewet, causing the surface fiber web 2 to If it exceeds 15 g/m ² and the back layer fiber web 3 exceeds 23 g/m ² , the required body fluid permeability will not be obtained and the surface will bleed. 1st fiber 4 is 80
If it is less than % by weight, the required bonding (fusion) strength,
Softness and body fluid permeability cannot be obtained, and the third fiber 5
If it is less than 20% by weight, the required bulk and elastic compression recovery rate will not be achieved and body fluids will rewet.
If it is super, the amount of the first fiber 4 used will be reduced,
Disadvantages arise when the first fibers 4 are less than 80% by weight. Although it is preferable that 100% by weight of the first fibers 4 be used in the surface layer fiber web 2, other second fibers may be used. This second fiber has a denier of 1.5 to 3, and
Normal polyester (melting point: 255 to 260°C) - low melting point polyester (melting point: 100 to 150°C) core-sheath type composite fiber, the above-mentioned normal polyester single fiber, polypropylene-polyethylene core-sheath type composite fiber, singly or in combination. is preferred. The denier of the first, second and third fibers is
Each of the above deniers is preferred, but in particular:
The denier of the first fibers 4 of the surface layer fiber web 2 should be such from the viewpoint of texture and feel, and the denier of the third fibers 5 of the back layer fiber web 3 should be such from the viewpoint of waist strength. is preferred. The top sheet 1 is prepared by mixing the above-mentioned fibers, forming front and back layer fiber webs 2 and 3 using a required web forming method, preferably a carding machine, and then
These are laminated together, and the laminated web is heat-treated at a temperature equal to or higher than the melting point of the polyethylene 4b of the first fibers 4 using a hot air heating device or a heating and pressing device. By the heat treatment, the front and back layer fiber webs 2, 3
The fibers are polyethylene 4b of the first fiber 4,
This is fused through the molten polyethylene at each intersection or mere contact point with other fibers, ie, the second fibers (if they are mixed) and the third fibers 5. Here, it should be noted that
This is the next point. That is, the first fiber 4 before the heat treatment, as illustrated in FIGS. 2 and 3,
The polyester 4a is completely covered with the polyethylene 4b and intersects with the first fibers and with other fibers. However, when heat treated, polyethylene 4a
When treated at a relatively high temperature within the range above the melting point of polyethylene 4b, as illustrated in FIG.
When b becomes gelatinous, it flows through the polyester 4a, and the polyethylene partially becomes water droplets, and is unevenly distributed in many parts of the polyester, and due to the flow, the polyester is partially exposed, As the thickness of the polyethylene becomes partially thinner, the first fibers 4 become partially thinner. These unevenly distributed sites are the intersections of the fibers of both webs 2 and 3, mere contact points, and bent or curved portions of the first fibers 4, and are relatively often found at these intersections (see FIG. 7). This is thought to be because the flow of the polyethylene 4b, which has turned into gel-like water droplets, is stopped at the intersection and tends to stay there. Therefore, the fibers of both webs 2 and 3 are not only fused at the intersection of the fibers via the molten polyethylene 4b, but also fused by the polyethylene 4b' unevenly distributed at the intersection. It turns out. The first fiber 4 is made of polyethylene 4 as described above.
b is partially unevenly distributed in the polyester 4a, and the polyester maintains its original fiber form to form the top sheet 1.
In order to obtain the desired structure, the polyester has a denier of 0.5 to 1.5, and
The weight ratio of the polyester to the polyethylene is preferably 1:0.6 to 1.2. In order to achieve the purpose of using the third fiber 5, it is preferable that the third fiber 5 exhibits crimps having at least 20 ridges per inch. This may be a non-hollow one as shown in FIG. 5A, or a hollow one as shown in FIG. 5B. The top sheet 1 obtained as described above is 1
Dry thickness 0.5~2mm under load of g/ ^cm2 ,
It is preferable that the thickness when wet is 0.3 to 1.7 mm, especially in order to prevent body fluids from rewetting. In addition, the top sheet 1 has a longitudinal tensile strength of at least 2000 g/25 mm, and a longitudinal tensile strength of at least 2000 g/25 mm.
Preferably it is 200g/25mm. The top sheet 1 having such thickness and tensile strength is
According to the present invention, this can be achieved reliably. In addition, the top sheet 1 obtained as described above
is used for absorbent articles such as sanitary napkins and disposable diapers as illustrated in FIG. Generally, such articles include an absorbent body 7 interposed between a top sheet 1 and a water-impermeable back sheet 6.
It consists of [Example] Examples and comparative examples are shown in the table below. Heat treatment is performed using a hot air heating device at a hot air temperature of 145
It was carried out at ~148°C, a wind speed of 1 m/sec, a wind pressure of 5-10 mag, and a transfer speed of 60 m/min while the upper surface of the surface layer fiber web was applied to a roll at a temperature of 130-132°C. The performance tests in the table below are as follows. Bending resistance: Based on the Clark method specified in JIS L 1096. Strength and elongation Specimen width 25mm, grip width 50mm, tensile speed 100
mm/min, MD is 5%, strength at 10% elongation (g/25mm) and maximum strength (g/25mm), CD is 5%,
The strength (g/25 mm) at 10% and 50% elongation was measured, and the force and % elongation for both MD and CD were measured. Elastic compression recovery rate Cut the test piece into a size of 100 x 100 mm, and
Stack 10 test pieces, apply a load of 3.0 g/cm ² to the stacked test pieces for 1 minute and measure the thickness ( ₁ V _3.0 ), then apply a load of 40 g/cm ² for 1 minute and measure the thickness ( _V1 ). It was left unloaded for 5 minutes, a load of 3.0 g/cm ² was applied, the thickness after recovery was measured ( ₂ V _3.0 ), and the value was calculated using the following formula. However, this is a measurement method when the test piece is dry;
As for the measurement method when wet, after the above procedure, the sample was immersed in water at 20° C. for 1 minute, a load of 35 g/cm ² was applied for 1 minute, and after draining the water, measurement was performed according to the procedure described above. Note that the load used was a weight with a size of 100 x 100 mm. ₂ V _3.0 −V ₁ / ₁ V _3.0 −V ₁ ×100 Texture The texture (softness) was sensory tested. ◎...Good ○...Slightly good ×...Poor fuzz removal The test piece was cut into a size of 100 x 100 mm, and its upper surface was lightly rubbed from end to end with a commercially available polyurethane scrubber. ◎...Fiber detachment is not observed.○...Fiber detachment is hardly observed, but fluffing is observed.△...Fiber detachment and fluffing are somewhat noticeable ×...Rewetting test where fiber detachment and fluffing are significant. Cut the piece into a size of 150 x 250 mm, place it on a crushed pulp mat, inject 800 c.c. of artificial urine into the center of the test piece for 9 seconds, and start injection at 5.
After 3 minutes, 40 pre-weighed filter papers and a 3.5Kg weight were placed on the injection site for 3 minutes. This state was left for 3 minutes, and the above operation was repeated twice. The weight of the filter paper after use - the weight of the filter paper before use/the weight of artificial urine injected x 100 (%). Bleeding The above-mentioned operation in the measurement of rewetting was performed, and 3 minutes after the start of injection, the vertical and horizontal lengths of the bleeding of the test piece were measured. Residual Amount The above-mentioned operation in the above-mentioned RIET measurement was performed, and 3 minutes after the start of injection, the amount of artificial urine remaining in the test piece was measured. Then, it was calculated as the test piece weight after injection minus the test piece weight before injection.

【table】

【table】

【table】

〔Effect of the invention〕

According to the first surface sheet of the present invention, as understood from the Examples and Comparative Examples, bending resistance, tensile strength (strength elongation), elastic compression recovery rate, texture, shedding, rewetting, bleeding, Excellent in terms of residual liquid volume, etc. In particular, it contains a relatively large amount of first fibers that fuse the fibers of the topsheet and have polyethylene on the fiber surface that is softer than other fibers, and the fibers include not only the polyethylene at the intersection points, but also Since the polyethylene partially distributed at the intersection points is also fused and the fused area is large, it is excellent in tensile strength, texture, and shedding. In particular, the polyester of the first fiber through which bodily fluids easily flow is partially exposed,
In addition, since it contains a relatively large amount of crimped third fibers, it is excellent in rewetting, bleeding, and residual liquid amount. According to the second method of manufacturing a sheet of the present invention,
Since the fiber web constituting the topsheet contains a relatively large amount of the first fibers, which are a polyester-polyethylene core-sheath type composite having a relatively large melting point difference, based on the melting point of the polyethylene, It is relatively easy to perform the heat treatment or adjust the temperature, and the melting point is higher than that of the polyethylene, and the fiber morphology and strength of the polyester, which forms the fiber structure of the web, cannot be reduced by the heat treatment. do not have. In addition, since the melting point difference is relatively large, uneven distribution of a portion of the polyethylene at the intersection points and exposure of a portion of the polyester in the first surface sheet of the present invention can be prevented at a relatively high temperature (the polyester This can be done relatively easily by treating a portion of the polyethylene at a temperature below the melting point of the polyethylene to form a gel-like water droplet and causing it to flow.

[Brief explanation of the drawing]

FIG. 1 is a partial perspective view of the topsheet of the present invention, FIG. 2 is a sectional view of the first fibers constituting the topsheet, FIG. 3 is a reproduction of an example of the intersecting state of the first fibers, and FIG. Fig. 3 is a copy of an example of a state in which a part of polyethylene in the fiber is unevenly distributed and a part of polyester in the fiber is exposed, and Fig. 5 A and B are copies of another state forming the top sheet. A third cross-sectional view of the fibers, FIG. 6 is a partial cross-sectional view of an absorbent article to which the above-mentioned topsheet is applied, and FIG. 7 is a 96 times enlarged micrograph of the shape of the fibers. 1... Surface sheet, 2... Surface fiber web, 3
...Back layer fiber web, 4...First fiber, 4a...
Polyester, 4b...Polyethylene, 4b'...
Unevenly distributed portion of polyethylene, 5...Third fiber, 5a
...High shrinkage polyester, 5b... Normal polyester, 6... Back sheet, 7... Absorbent material.

Claims (1)

[Scope of Claims] 1. A top sheet of an absorbent article comprising a fibrous web containing at least 65% by weight of 1.5 to 3 denier fibers which are a core-sheath type composite of polyester-polyethylene, wherein the fibers of the web are . The top sheet, wherein the top sheet is fused by the polyethylene on the intersection points of the fibers of the web, and is also fused by the polyethylene partially distributed at the intersection points. 2 80 to 100% by weight of 1.5 to 3 denier first fibers, which are polyester-polyethylene core-sheath type composites.
and 0-20% by weight of other secondary fibers 7-15
g/ ^m2 surface fiber web and said first fibers 60-80
15 to 23 g/m ² of backing fiber web consisting of 20 to 40 weight % of polyester-high shrinkage polyester side-by-side composite crimped 2 to 6 denier third fibers. Laminated,
The fibers of the web are fused by the polyethylene of the first fibers at the intersections of the fibers of the web, and are also fused by the polyethylene partially unevenly distributed at the intersections. The top sheet according to item 1. 3. The top sheet according to claim 1, wherein a portion of the polyester of the first fiber is exposed. 4. The topsheet according to claim 1, wherein the polyester of the first fiber has a denier of 0.5 to 1.5. 5. The topsheet according to claim 1, wherein the first fiber has a weight ratio of polyester to polyethylene of 1:0.6 to 1.2. 6. The second fiber has a denier of 1.5 to 3, and
Normal polyester (melting point: 225 to 260°C) - low melting point polyester (melting point: 100 to 150°C) core-sheath composite fiber, normal polyester single fiber, polypropylene-polyethylene core-sheath composite fiber, singly or in combination. The top sheet according to claim 2, which is. 7. The third fiber has at least 20 fibers per inch.
3. The top sheet according to claim 2, wherein the top sheet has crimps having a number of ridges. 8 Dry thickness under a load of 1g/ ^cm2 is 0.5~
2 mm, and the surface sheet according to claim 1, which has a wet thickness of 0.3 to 1.7 mm. 9 Tensile strength in longitudinal direction is at least 2000g/25
3. The top sheet according to claim 2, having a transverse weight of at least 200 g/25 mm. 10 At least 65 polyester-polyethylene core-sheath composite fibers of 1.5 to 3 denier
By heat-treating a fiber web containing % by weight, the fibers of the web are fused by the polyethylene at the intersections of the fibers of the web, and at least a portion of the polyethylene is fluidized and unevenly distributed at the intersections. A method for manufacturing a topsheet of an absorbent article, characterized in that the fibers of the web are also fused by the polyethylene that has been applied. 11 Polyester-polyethylene core-sheath type composite consisting of 80-100% by weight of 1.5-3 denier first fibers and 0-20% by weight of other second fibers 7-
15g/ ^m2 surface fiber web and the first fiber 60~
80% by weight and a side-by-side composite of polyester - high shrinkage polyester -
15 consisting of 20-40% by weight of 6 denier tertiary fibers
By laminating a back layer fiber web of ~23 g/m ² and heat-treating the web, the fibers of the web are fused by the polyethylene of the first fibers at the intersections of the fibers of the web, and the fibers of the web are fused at the intersections of the fibers of the web. At least a portion of the polyethylene of the first fibers is flowed unevenly, and the unevenly distributed polyethylene of the first fibers also fuses the fibers of the web, and the third fibers are crimped. A method for manufacturing a topsheet according to claim 9, wherein the method comprises: 12 exposing at least a portion of the polyester of the first fiber by causing at least a portion of the polyethylene of the first fiber to flow unevenly;
A method for manufacturing a topsheet according to claim 10. 13. The method for manufacturing a topsheet according to claim 10, wherein the polyester of the first fiber has a denier of 0.5 to 1.5. 14. The method for manufacturing a topsheet according to claim 10, wherein the weight ratio of polyester and polyethylene of the first fibers is 1:0.6 to 1.2. 15 The second fiber has a denier of 1.5 to 3 and is a core-sheath composite fiber of normal polyester (melting point: 255 to 260°C) - low melting point polyester (melting point: 100 to 150°C), or the normal polyester single fiber. , polypropylene-polyethylene core-sheath composite fibers alone or in combination, claim 11.
2. Method for manufacturing the surface sheet described in Section 1. 16 The third fiber has at least
12. The method for manufacturing a topsheet according to claim 11, wherein crimps having 20 ridges occur.