JP2003299690A - Absorptive article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an absorptive article for effectively preventing lateral leakage by improving joining of a leakage preventive sheet, a surface sheet, and an absorber. <P>SOLUTION: In this absorptive article 1, an upper surface in lengthwise directional both side parts of the absorber 4 is covered with the leakage preventive sheet 6. The absorber 4, the leakage preventive sheet 6 and the surface sheet 2 are integrated, and the leakage preventive sheet 6 is composed of a thermoplastic resin compatible with a thermoplastic resin for constituting the surface sheet 2. Surface energy of an opposed surface with the absorber 4 in the leakage preventive sheet 6 is heightened more than an opposed surface with the surface sheet 2 in the leakage preventive sheet 6. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a sanitary napkin,
The present invention relates to absorbent articles such as incontinence pads, panty liners, and disposable diapers, and more particularly to absorbent articles excellent in preventing side leakage.

[0002]

2. Description of the Related Art The applicant of the present invention has previously filed Japanese Patent Application Laid-Open Nos. 9-70413 and 2001-2001.
In JP-A-37810 and JP-A-2001-120597, an upper surface, a back surface and a side surface of both sides in a longitudinal direction of an absorber are covered with a leak preventive sheet, and the leak preventive sheet is heat-pressed together with the surface sheet and the absorber to be integrated. An absorptive absorbent article was proposed. According to this absorbent article, lateral leakage of the surface sheet is suppressed by the leak preventive sheet, and side leakage is effectively prevented.

The leak-proof sheet is generally composed of a thermoplastic resin film in order to enhance the leak-proof property. On the other hand, the absorber is generally composed of cellulosic fibers such as pulp fibers in order to enhance its liquid absorbency. In particular, it is known that cellulosic fibers do not have good sealing properties with thermoplastic resins. Therefore, when the leak-proof sheet is heat-pressed together with the surface sheet and the absorber, it is not easy to sufficiently join the leak-proof sheet and the absorber. As a result, the side leakage prevention effect of the leakage prevention sheet may not be sufficiently exerted. Therefore, conventionally, the leak-proof sheet is composed of a laminate of a thermoplastic film and paper, the surface of the thermoplastic film in the leak-proof sheet is joined to the surface sheet, and the surface of the paper is joined to the absorber, It secured a sufficient joining force.

However, since a leak-proof sheet made of a laminate of a thermoplastic film and paper has high rigidity, an absorbent article using the leak-proof sheet may not have good wearing comfort and fit. Further, it is not economical to use a leak-proof sheet made of a laminate.

Therefore, an object of the present invention is to provide an absorbent article in which the leak-proof sheet, the surface sheet and the absorbent body are bonded well, and lateral leakage can be effectively prevented. Another object of the present invention is to provide an absorbent article which has a good wearing feeling and fit and can be manufactured economically.

[0006]

The present invention has a liquid-permeable top sheet, a liquid-impermeable back sheet, and a liquid-retaining absorber interposed between both sheets, and has a substantially vertical shape. In the absorbent article of, at least the upper surfaces at both sides in the longitudinal direction of the absorbent body are covered with a liquid-impermeable, single-layer leakproof sheet, and the absorbent body, the leakproof sheet, and the surface sheet have heat and pressure. And the leakage-preventing sheet is made of a thermoplastic resin having compatibility with the thermoplastic resin constituting the surface sheet, and the absorber in the leakage-preventing sheet. The object is achieved by providing an absorbent article in which the surface energy of the facing surface is higher than that of the facing surface of the leak-proof sheet with the surface sheet.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described based on its preferred embodiments with reference to the drawings. In Figure 1,
A perspective view of a sanitary napkin as one embodiment of the present invention is shown, and FIG. 2 shows a sectional view taken along line II-II in FIG. The sanitary napkin 1 of the embodiment shown in FIGS. 1 and 2 has a vertically long shape, and has a liquid-permeable top sheet 2, a liquid-impermeable back sheet 3, and a liquid interposed between both sheets. It has a retentive absorber 4.

The surface sheet 2 has a size larger than that of the absorber 4. The topsheet 2 covers the entire upper surface side of the absorber 4, further covers both side portions in the longitudinal direction of the absorber 4, and reaches both left and right side portions on the back surface side of the absorber 4. On the other hand, the back sheet 3 has substantially the same width as the absorber 4 and a longer length than the absorber 4. The backsheet 3 covers the entire backside of the absorber 4. The backsheet 3 and the topsheet 2 reaching the back side of the absorber 4 are joined and fixed by a predetermined joining means such as heat seal or hot melt adhesive. An adhesive for fixing the napkin 1 to clothes is applied to the outer surface of the back sheet 3 (not shown). This adhesive is protected by a release sheet (not shown).

The topsheet 2 and the backsheet 3 extend from the front and rear ends of the absorbent body 4, and the extended sheets 2 and 3 are joined and fixed to each other by joining means such as heat sealing.

On the surface sheet side of the napkin 1, there is formed an oval closed first groove 5 in which the surface sheet 2 and the absorber 4 are integrally formed. The integration of the topsheet 2 and the absorber 4 is achieved by applying heat and pressure, for example. Specifically, the groove 5 can be formed by passing the topsheet 2 and the absorber 4 between both rolls using an embossing device consisting of a ridge roll heated to a predetermined temperature and a smooth roll. . Groove 5 is napkin 1
The napkin 1 is formed so as to be easily deformed in conformity with the shape of the wearer's body when worn. Further, the excreted liquid is formed so as to be dammed and guided in the longitudinal direction of the napkin 1 before spreading laterally and leaking from the side edge of the napkin 1.

Leak-proof sheets 6 are arranged on both sides of the absorbent body 4 in the longitudinal direction so as to directly cover the both sides 4a. Specifically, the leak-proof sheet 6 is arranged between the back sheet 3 and the absorber 4 and directly covers the entire back surface side of the absorber 4. Further, the leak-proof sheet 6 covers both sides in the longitudinal direction of the absorbent body 4, reaches the upper surface side of the absorbent body 4, and is interposed between the absorbent body 4 and the surface sheet 2. That is, the leak-proof sheet 6 is arranged between the topsheet 2 and the absorber 4 on the side of the topsheet of the napkin 1, while it is arranged between the backsheet 3 and the absorber 4 on the side of the backsheet. Has been done. As a result, the leak-proof sheet 6 has an upper surface on both sides in the longitudinal direction of the absorber 4,
The back and side surfaces will be coated directly. By disposing such a leak preventive sheet 6, on the surface sheet side of the napkin 1, that is, on the wearer contact surface side, a pair of hydrophobic regions A extending in the longitudinal direction on both sides in the longitudinal direction of the napkin 1. Is formed, and between the hydrophobic regions A and A,
A water absorbing region B extending in the longitudinal direction of the napkin 1 is formed.

In addition to the first groove 5 described above, on the side of the top sheet of the napkin 1, a second linear member extending in the longitudinal direction of the napkin 1 is provided outside the groove 5 in the width direction. A pair of grooves 7 and 7 are formed. The second groove 7 is formed by integrally joining the leak-proof sheet 6 with the topsheet 2 and the absorber. This integration is achieved by applying heat and pressure, ultrasonic sealing, or the like, as in the case of the first groove 5. Specifically, an embossing device consisting of a ridge roll and a smooth roll heated to a predetermined temperature is used, and the surface sheet 2 and the leakproof sheet 6 are placed between both rolls.
Also, the second groove 7 can be formed by passing the absorber 4.

Since the leak-proof sheet 6 is bonded to the surface sheet 2 on the skin-contacting surface side of the absorbent body 4, the liquid that has permeated the surface sheet 2 is separated from the surface sheet 2 and the leak-proof sheet 6. Leakage from the side portion of the napkin 1 is prevented. Further, since the leak-proof sheet 6 is joined and integrated with the topsheet 2 and the absorbent body 4, even if the absorbed liquid diffuses in the absorbent body, the second groove 7 becomes a barrier and both sides of the absorbent body are covered. It is possible to suppress the spread of the liquid to the part. Furthermore,
Even if a large amount of liquid is discharged at one time and the liquid spreads to the side of the second groove 7, the leak-proof sheet 6 can prevent leakage from the side of the napkin 1, that is, side leakage.

As the topsheet 2 of the napkin 1 having the above structure, a non-woven fabric made of thermoplastic resin fibers or a perforated film can be used. Back sheet 3
As the material, a thermoplastic resin film can be used. This film may have moisture permeability. As the absorbent body 4, use a laminated product of pulp fibers, which is a type of cellulose fiber, and particles of superabsorbent polymer, or absorbent paper in which particles of superabsorbent polymer are held and fixed between pulp fibers. You can

As the leak-proof sheet 6, a liquid-impermeable, single-layer film or a non-woven fabric made of a thermoplastic resin compatible with the thermoplastic resin constituting the surface sheet 2 is used. Thereby, when forming the 2nd groove | channel 7, the joining force by the heat fusion of the surface sheet 2 and the leakproof sheet 6 can be improved. From the viewpoint of increasing the bonding strength, the leak-proof sheet 6 is preferably made of the same thermoplastic resin as the thermoplastic resin forming the topsheet 2. When the topsheet 2 is composed of two or more kinds of resins, for example, when the topsheet 2 is composed of a non-woven fabric of composite fibers having a core-sheath structure, the resin forming the outermost surface of the topsheet 2, that is, In this case, the leakproof sheet is formed by using a resin that is compatible with the resin forming the sheath.

In the leak-proof sheet 6 made of a single-layer film or nonwoven fabric, the surface energy of the surface facing the absorber 4 (hereinafter, this surface is referred to as the absorber facing surface) is the surface facing the surface sheet 2 (hereinafter this The surface is referred to as the surface sheet facing surface)). As a result, the joining force between the thermoplastic resin, which is a combination of materials having poor sealing properties, and the pulp fiber is increased, and the second groove 7 can be firmly formed. As a result, the above-mentioned side leakage effect can be maintained. Further, by using the leak-proof sheet in which the surface energy of the surface facing the absorber is increased, it is not necessary to use a laminate of paper and a thermoplastic resin film as in the conventional case, so that the manufacturing cost of the napkin 1 can be reduced. You can Also,
Since it is easier to control the rigidity of the leak-proof sheet as compared with the case of using a laminate, the wearing feeling and fit of the napkin 1 can be enhanced.

In order to make the surface energy of the absorber facing surface higher than that of the surface sheet facing surface, for example, the absorber facing surface may be subjected to a surface modification treatment. A corona discharge treatment is a typical example of the surface modification treatment. Of course, other surface modification treatments such as chromic acid treatment, flame treatment, hot air treatment, ozone / ultraviolet treatment may be performed. When performing corona discharge treatment, polyester film, Hypalon, E
A pair of metal rolls covered with P rubber etc.
They are arranged at intervals of about 0.6 mm, and a high voltage of several thousand to tens of thousands of V is applied at a high frequency of several hundred kc / s.

Surface tension can be used as a quantitative measure of surface energy. However, it is not easy to measure the surface tension of the surface of the leakproof sheet 6, that is, the solid surface. Therefore, in the present invention, the test liquid mixture [ethylene glycol monoethyl ether, formaldehyde] applied to the surface of the leakproof sheet 6 is used. (Special grade of JIS K8873 or higher) prepared by stepwise mixing; JIS K67
68] is used as a measure of surface energy. The surface tension is measured according to JIS K6768 (plastic film and sheet wetting tension test method), and is a value at 23 ° C. and 50% RH. In the present specification, the term "surface tension" means a value measured according to this method and under these conditions. In the present invention, the surface tension of the surface of the leakproof sheet 6 facing the absorber is 35d.
yn / cm or more, particularly 35 to 56 dyn / cm, especially 40 to 56 dyn / cm, the surface energy of the absorber facing surface becomes higher than that before the surface modification treatment, and the absorber facing surface is absorbed. It is preferable because the joining force by heat fusion with the body is sufficiently increased. On the other hand, the surface tension of the surface of the leakproof sheet 6 facing the top sheet does not need to be higher than the surface tension of the surface facing the absorber.
If it is about 34 to 34 dyn / cm, especially about 32 to 33 dyn / cm, the joining force by heat fusion between the surface sheet facing surface and the surface sheet 2 becomes sufficiently high.

As described above, the leak-proof sheet 6 is made of a thermoplastic resin film or nonwoven fabric. As the thermoplastic resin, a conventionally known thermoplastic resin can be used without particular limitation. In particular, when a thermoplastic resin composition containing 10 to 35% by weight, especially 15 to 25% by weight of high density polyethylene (HDPE) as a thermoplastic resin is used, the napkin 1
The leak-proof sheet 6 is less likely to stretch in the manufacturing process of
It is preferable in that the transportability is enhanced. Further, since it has appropriate rigidity, it has good workability. When the amount of HDPE is 35% by weight or more, the rigidity becomes too high and the fit of the napkin 1 is deteriorated, or a so-called crisp feeling is likely to occur. When a thermoplastic resin composition containing HDPE is used, it is preferable to use low density polyethylene (LDPE) or linear low density polyethylene (LLDPE) as the other resin component. That is, when a thermoplastic resin composition containing HDPE is used, it is preferable that the thermoplastic resin composition is a polyethylene resin composition.

From the viewpoint of improving the transportability of the leakproof sheet 6 in the manufacturing process of the napkin 1, and particularly from the viewpoint that the leakproof sheet 6 does not meander and its arrangement position (method) on the product is stable, 5 of the leakproof sheet 6 is provided. The tensile strength at% extension is preferably 70 cN or more, particularly 100 cN or more in the longitudinal direction (conveying direction) of the leak-proof sheet. The upper limit value of the tensile strength at 5% elongation is determined by the basis weight and thickness of the leak-proof sheet 6, the basis weight is 18 to 25 g / m ² , and the thickness is 20 to 40.
In a leak-proof sheet of μm, the value is generally about 200 cN. The tensile strength is measured under the conditions that the width of the sample piece is 10 mm, the chuck distance is 100 mm, and the pulling speed is 300 mm / min.

The leak-proof sheet 6 has a basis weight of 10 to 30 g /
m ^2, particularly a low basis weight of about 15-25 g / m ² is preferable from the viewpoint of improving the wearing feel and fit due to the decrease in the rigidity of the barrier sheet 6 due to low basis weight. If the basis weight of the leak-proof sheet 6 is less than 10 g / m ² , the rigidity is too low and the transportability and processability deteriorate. Further, the leak-proof sheet 6 is easily broken when the second groove is formed.

The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the entire back surface side of the absorber 4 is covered with the leak preventive sheet 6, but instead of this, only the both sides in the longitudinal direction of the absorber 4 may be covered with the leak preventive sheet 6. Good. In this case, a pair of narrow leakproof sheets 6 may be used.

Further, a large number of small holes may be formed in the second groove so that the liquid can be guided to the absorber through the small holes.

Although the above-mentioned embodiment relates to a sanitary napkin, the present invention can be applied to other absorbent articles such as incontinence pads, panty liners and disposable diapers as well.

Example 1 As a leak-proof sheet, a film made of a thermoplastic resin composition having the composition shown in Table 1 was used. Corona discharge treatment was applied to only one side of this film. The basis weight and tensile strength of the film at 5% elongation in the longitudinal direction are shown in Table 1. The surface tension of each surface of the film after the corona discharge treatment was as shown in Table 1.

As the surface sheet, an air-through nonwoven fabric of a core-sheath type composite fiber having a core made of polyethylene terephthalate and a sheath made of polyethylene (basis weight: 25 g / m ² ) was used. Polyethylene film (basis weight 2
5 g / m ² ) was used. Further, as an absorber, a piled product of pulp fibers and particles of a superabsorbent polymer (basis weight 210 g
/ M ² ) was used. 1 and 2 using these materials
The sanitary napkin shown in was produced. An embossing device including a ridge roll and a smooth roll was used to form the first and second grooves. The heating temperature of the roll was 180 ° C.

[Examples 2 and 3] Table 1 as a leak-proof sheet
A sanitary napkin was obtained in the same manner as in Example 1 except that the one shown in 1 was used.

[Comparative Examples 1 to 3] Sanitary napkins were obtained in the same manner as in Example 1 except that the leakproof sheets shown in Table 1 were used.

[Comparative Example 4] A sanitary napkin was obtained in the same manner as in Example 1 except that the leak-proof sheet shown in Table 1 was used and the surface opposite to Example 1 was subjected to corona discharge treatment. .

[Performance Evaluation] With respect to the sanitary napkins obtained in Examples and Comparative Examples, the following method was used to bond the surface sheet and the leakproof sheet, bond the leakproof sheet and the absorbent body, and prevent The transportability and processability of the leaked sheet were evaluated.
The results are shown in Table 1.

[Jointness between Top Sheet and Leak-Proof Sheet] The value of the peel strength between the top sheet and the leak-proof sheet is used as a measure of the jointability. The method for measuring the peel strength is as follows. In the central region of the napkin in the longitudinal direction, the napkin is cut at two locations (30 mm intervals) in parallel to the napkin width direction, and a section is cut out (dimension of section: 30 mm in longitudinal direction x napkin width in width direction). Then, only the topsheet is cut at both side edges in the width direction of the section so that the peel strength between the topsheet and the leakproof sheet joined at the position of the second groove 7 can be measured. Push-pull gauge (made by AIKOH) for measurement
To use. The peel strength between the surface sheet and the leakproof sheet in the direction (width direction) intersecting the longitudinal direction of the napkin is measured and the maximum value is recorded. The measurement is performed using five napkins. The average value of 5 points is taken as the peel strength value.

[Jointness between Leak-Proof Sheet and Absorber] The value of the peel strength between the leak-proof sheet and the absorber is used as a measure of the jointability. The method for measuring the peel strength is as follows. As mentioned above,
A section is cut out in the same procedure as in the case of measuring the peel strength between the topsheet and the leakproof sheet. Then, the surface sheet and the leakproof sheet are cut at both side edges in the width direction of the section, so that the joining strength between the leakproof sheet joined at the position of the second groove 7 and the absorber can be measured. After that, the peel strength is obtained in the same manner as the measurement of the peel strength between the surface sheet and the leakproof sheet.

[Conveyability and Workability of Leak-Proof Sheet] Concerning the conveyability, 100 pieces of machine-made napkins were inspected, and the difference in width between the portions of the leak-proof sheet covering the absorber was 3 mm or less. Those that were evaluated as “good” (◯), and other than that were evaluated as “bad” (x). Regarding workability, 100 napkins manufactured by a machine were inspected, and when there was no break or tear of the leakproof sheet at the position of the second groove 7 and there was no floating of the second groove 7, it was judged as good (○). Other than defective (×)
And

[0034]

[Table 1]

As is clear from the results shown in Table 1, the napkins of the examples (the products of the present invention) have good bondability between the surface sheet and the leakproof sheet and bondability between the leakproof sheet and the absorber. I know there is. Further, it can be seen that the leakage preventive sheet has good transportability and processability in the manufacturing process. On the other hand, in the napkin of the comparative example in which the surface of the leakproof sheet facing the absorber is not subjected to corona discharge treatment, it can be seen that the bondability between the leakproof sheet and the absorber is not good.

[0036]

INDUSTRIAL APPLICABILITY In the absorbent article of the present invention, the leak-proof sheet, the surface sheet and the absorbent body are bonded well, and side leakage can be effectively prevented. Further, the absorbent article of the present invention has good wearing feeling and fit, and can be economically manufactured.

[Brief description of drawings]

FIG. 1 is a perspective view showing a sanitary napkin according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

[Explanation of symbols]

1 Sanitary napkins (absorbent articles) 2 Top sheet 3 back sheet 4 absorber 5 first groove 6 leak-proof sheet 7 second groove

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Harumi Miura             Kao Stock Exchange 2606, Akabane, Kai-cho, Haga-gun, Tochigi Prefecture             Company research institute F term (reference) 3B029 BC05                 4C003 CA05 DA04                 4C098 AA09 CC03 CC05 CC08 CC10                       CC11 CC15 CC33 CC37 DD02                       DD03 DD06 DD10 DD23 DD25                       DD26

Claims (5)

[Claims] 1. A substantially vertical absorbent article having a liquid-permeable top sheet, a liquid-impermeable back sheet, and a liquid-retaining absorber interposed between the two sheets, wherein At least the upper surfaces on both sides in the longitudinal direction of the body are covered with a liquid-impermeable, single-layer leakproof sheet, and the absorber, the leakproof sheet and the surface sheet are integrated by applying heat and pressure. Further, the leak-proof sheet is composed of a thermoplastic resin having compatibility with the thermoplastic resin constituting the surface sheet, and the surface energy of a surface of the leak-proof sheet facing the absorber is An absorbent article having a height higher than that of a surface of the leakproof sheet facing the surface sheet. 2. The surface of the leak-proof sheet facing the absorber is subjected to a surface modification treatment so that the surface energy of the surface is higher than that of the leak-proof sheet facing the surface sheet. The absorbent article according to claim 1, wherein 3. The absorbent article according to claim 2, wherein the surface modification treatment is corona discharge treatment. 4. The surface tension (23 ° C., 50% RH) measured according to JIS K6768 on the surface of the leakproof sheet facing the absorber is 35 dyn / cm or more, and the surface of the leakproof sheet is The surface tension (23 ° C., 50% RH) on the surface facing the sheet is 30 to 34.
It is dyn / cm, The absorbent article in any one of Claims 1-3. 5. The absorbent article according to claim 1, wherein the leak-proof sheet covers the upper surface, the back surface, and the side surfaces of both side portions in the longitudinal direction of the absorbent body.