JP3657053B2 - Disposable diapers - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a disposable diaper having excellent fit, low skin irritation, and good moldability.
[0002]
[Background Art and Problems to be Solved by the Invention]
Conventionally, as a disposable diaper, it comprises a liquid-permeable top sheet, a liquid-impermeable back sheet and a liquid-retaining absorbent interposed between both sheets, on the left and right side edges of the back side part, A pair of fastening tapes for diaper fastening is widely used.
In recent years, in order to further improve the fit and leakage prevention properties of diapers, it has been proposed to provide the fastening tape itself with elastic stretchability.
[0003]
However, conventionally, when applying elastic elasticity to the fastening tape, since the fastening tape is formed of ordinary rubber or the like, the fastening tape hits the wearer's skin during wearing, and the wearer's skin is stimulated, etc. There was a problem.
In addition, the above-described normal rubber has a problem that molding processability is poor and productivity is poor.
[0004]
Accordingly, an object of the present invention is to provide a disposable diaper having excellent fit, low skin irritation, and excellent moldability.
[0005]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have found that a disposable diaper having a fastening tape comprising a specific stretchable elastic nonwoven fabric can achieve the above-mentioned object.
[0006]
The present invention has been made on the basis of the above knowledge, and comprises a liquid-permeable top sheet, a liquid-impermeable back sheet, and a liquid-retaining absorbent interposed between the two sheets, In a deployable disposable diaper in which a pair of fastening diaper fastening tapes are arranged on both left and right edges, the fastening tape has a hard elastic component made of crystalline polypropylene as a first component and a thermoplastic elastomer as a second component. Ri Na comprises a stretchable elastic nonwoven fabric made of stretchable elastic composite fibers as a component, the stretchable elastic composite fibers, the first component is in the sheath, Ru sheath-core type composite fibers der the second component is a core The present invention provides a disposable diaper characterized by the above (hereinafter, the first invention refers to this invention) .
The present invention also includes a liquid-permeable top sheet, a liquid-impermeable back sheet, and a liquid-retaining absorbent interposed between the two sheets. In a deployable disposable diaper in which a fastening tape for diaper fastening is arranged, the fastening tape is made of a stretch elastic composite fiber having a hard elastic component made of crystalline polypropylene as a first component and a thermoplastic elastomer as a second component. The thermoplastic elastomer is an ethylene-α-olefin copolymer produced by using a metallocene compound as a catalyst, and provides a disposable diaper characterized in that Hereinafter, the second invention refers to this invention) .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the disposable diaper of the present invention will be described in more detail.
The disposable diaper of the present invention is characterized in that the fastening tape comprises a specific stretchable elastic nonwoven fabric.
[0008]
The stretchable elastic nonwoven fabric used in the present invention is composed of stretchable elastic composite fibers having a hard elastic component made of crystalline polypropylene as a first component and a thermoplastic elastomer as a second component.
[0009]
The crystalline polypropylene used as the hard elastic component which is the first component can be used without particular limitation as long as it has hard elastic properties. Preferable examples of the crystalline polypropylene include a homopolymer of propylene, a copolymer with ethylene mainly composed of propylene, and a copolymer with α-olefin mainly composed of propylene.
[0010]
The crystalline polypropylene preferably has a crystallinity of 40% or more. If the crystallinity is less than 40%, the fiber elongation recovery rate may be insufficient. The crystallinity is a value calculated based on the energy required for melting the crystal measured according to the DSC (Differential Scanning Calorimetry) method.
[0011]
The crystalline polypropylene preferably has a melt index of 1 to 200 g / 10 minutes, and more preferably 3 to 50 g / 10 minutes. If the melt index is less than 1 g / 10 minutes, the melt viscosity may be too high and spinning may be difficult, and if it exceeds 200 g / 10 minutes, the melt viscosity is too low and breakage may occur before fiberization. Since it may occur, it is preferable to be within the above range. The melt index is a value measured under a load of 2.16 kgf at 230 ° C. according to ASTM D-1238.
[0012]
Further, the crystalline polypropylene preferably has a weight average molecular weight of 10,000 to 1,000,000, and preferably has a weight average molecular weight of 20,000 to 60, from the viewpoint that the elastic elasticity is easily expressed and the composite fiber can be easily spun. More preferably, it is 10,000.
[0013]
The thermoplastic elastomer used as the second component is generally composed of a flexible component (soft segment, soft phase) having rubber elasticity in the molecule and a molecular constrained component (hard segment, hard phase) for preventing plastic deformation. ).
The thermoplastic elastomer can be classified according to the type of its hard segment. In the present invention, styrene elastomer, olefin elastomer, vinyl chloride elastomer, urethane elastomer, ester elastomer, amide elastomer, syndiotactic Poly (1,2-butadiene), poly (trans-1,4-isoprene) and the like can be preferably used, and among them, urethane elastomers and ester elastomers can be particularly preferably used.
[0014]
Examples of the urethane elastomer include a urethane elastomer composed of a block having a urethane bond as a hard segment and a block having a polycarbonate polyol, an ether polyol, a caprolactone polyester, an adipate polyester, or the like as a soft segment. Can be mentioned.
Examples of the ester elastomer include an ester elastomer composed of a block having an aromatic polyester as a hard segment and an aliphatic polyether or a block having an aliphatic polyester as a soft segment.
[0015]
In addition, as the thermoplastic elastomer, in consideration of processability, cost, light resistance, chemical resistance, skin irritation and the like, ethylene- produced according to a known method using a known metallocene compound as a catalyst. It is particularly preferable to use an α-olefin copolymer.
In the second invention, an ethylene-α-olefin copolymer produced using a metallocene compound as a catalyst is used as the thermoplastic elastomer.
In the ethylene-α-olefin copolymer, the α-olefin to be copolymerized with ethylene is an α-olefin having 3 to 30 carbon atoms such as propylene, 1-butene, 1-pentene, 1-hexene, 1 -Octene, 1-heptene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-pentene, octadecene and the like. Among these, 1-hexene, 1-octene, 1-heptene, and 4-methyl-1-pentene are preferably used. The blending ratio of ethylene and α-olefin in the ethylene-α-olefin copolymer is preferably 40 to 98% by weight of ethylene and 60 to 2% by weight of α-olefin.
[0016]
In the present invention, in order to modify the melt fluidity of these thermoplastic elastomers, a thermoplastic plastic, an oil component, or the like may be added to these thermoplastic elastomers.
[0017]
The thermoplastic elastomer has an elongation recovery rate of 100% or more when stretched at 100%. For example, when the stretchable elastic nonwoven fabric is used for clothing or the like, it does not cause damage to human movement. This is preferable in that it can be followed.
[0018]
In addition, the thermoplastic elastomer preferably has a permanent set of 50% or less, more preferably 0 to 30%, and a hysteresis ratio of preferably 5.0 or less, more preferably 1.0 to 3.5. -Α-olefin copolymer.
When the permanent set is 50% or less, the fixable region when the stretchable elastic nonwoven fabric is used in various products can be widened. When the hysteresis ratio is 5.0 or less, the stretchable elasticity Responsiveness of the nonwoven fabric is improved.
On the other hand, if the permanent strain exceeds 50% or the hysteresis ratio exceeds 5.0, it is not preferable because the fitting property of the fastening tape comprising the stretchable elastic nonwoven fabric may be deteriorated.
[0019]
The permanent set and the hysteresis ratio are each measured as follows.
Permanent strain measurement method: In the same manner as the hysteresis ratio measurement method described below, the sample length was measured when the sample was stretched 100% and then the initial distance between chucks was measured, and the initial length when stretched 100%. The ratio (%) of the length (the length of the portion that became longer than the initial length) that cannot be relaxed to the thickness (the distance between the initial chucks) was determined, and this was used as the permanent strain.
Hysteresis ratio measurement method: In order to examine the stretchability of each sample, the hysteresis ratio was measured using an elongation tester with an integrating device. That is, a sample (sheet) prepared with the thermoplastic elastomer was set based on JIS L1015 and L1096, and then each sample was stretched 100% at a speed of 300 mm / min to create a stretching curve, and then the same speed. And loosen at a point where the distance between the chucks reaches the initial length of 100 mm, create a relaxation curve, measure the area under the stretching curve and the relaxation curve, and substitute these into the following equation: The hysteresis ratio was calculated.
Hysteresis ratio = area under the stretching curve / area under the relaxation curve
In the composite fiber, the content of the first component is preferably 5 to 70% by weight, the content of the second component is 95 to 30% by weight, and more preferably, the content of the first component is The content is 10 to 60% by weight, the content of the second component is 90 to 40% by weight, and more preferably the content of the first component is 10 to 50% by weight. The component content is 90 to 50% by weight. If the content of the first component exceeds the upper limit or the content of the second component is less than the lower limit, the stretchability of the composite fiber may be insufficient. If the content is less than the above lower limit or the content of the second component exceeds the upper limit, the area where the second component is exposed on the surface of the composite fiber increases, and the tactile sensation may decrease. Moreover, since it may be difficult to spin the sheath-core type composite fiber, it is preferably within the above range.
[0021]
If the said composite fiber in 2nd invention is a fiber form which can express a stretching elasticity, there will be no restriction | limiting in particular in the fiber form. Preferred fiber forms of the composite fiber include a parallel type (side-by-side type), a split type (fiber cross-section divided into an arc shape), and a sheath core type (sheath core type (concentric and eccentric types). )] And the like. The composite fiber can be produced by using the first component and the second component by the known spinning method to form each of the above fiber forms. The fiber form of the composite fiber in the first invention is a sheath core type [sheath core type (concentric circle type and eccentric type)].
[0022]
The composite fiber produced by the known spinning method may be directly formed into a web after spinning to form a non-woven fabric, or after being subjected to a predetermined stretching treatment after spinning from the standpoint of further developing stretch properties. A nonwoven fabric may be formed as a web.
As conditions for the stretching treatment, the stretching temperature is preferably 20 to 130 ° C., and the stretching ratio is preferably 1 to 6 times. For the heating of the stretchable elastic composite fiber in the stretching treatment, for example, heating means such as hot air, steam, infrared rays or the like can be used.
[0023]
The composite fiber preferably has a fiber diameter of 1 to 20 denier, and more preferably 2 to 6 denier. If the fiber diameter is less than 1 denier, the spinnability in the spinning process may be reduced and fiberization may be difficult, and if it exceeds 20 denier, the texture may deteriorate in practicality of the stretchable elastic nonwoven fabric. It is preferable to be within the above range.
[0024]
The composite fiber preferably has a stretch recovery rate of 20 to 100% when stretched 100%, and more preferably 50 to 100%. If the stretch recovery rate is less than 20%, for example, when the stretchable elastic nonwoven fabric is used for clothing or the like, the function of following the movement of the human body may be insufficient.
[0025]
The composite fiber may be used in the form of a short fiber such as a staple fiber, or may be used in the form of a long fiber such as a continuous filament.
[0026]
The stretchable elastic nonwoven fabric is particularly preferably composed of 100% of the composite fiber, but may be blended with other fibers.
When the composite fiber is blended with other fibers, the stretchable elastic nonwoven fabric preferably contains 30% by weight or more, more preferably 50% by weight or more of the composite fiber. If the amount of the composite fiber is less than 30% by weight, the elastic elasticity of the elastic elastic nonwoven fabric may be remarkably lowered and may break.
Other fibers that can be blended with the above-mentioned composite fiber include fibers that are not altered by heat treatment in the nonwoven fabric forming process, for example, thermoplastic synthetic fibers such as polyolefin, polyester and polyamide, natural fibers such as cotton, hemp and wool, and rayon and Examples thereof include recycled fibers such as acetate, and various binder fibers that can be fused by the heat treatment.
[0027]
The stretchable elastic nonwoven fabric can be manufactured, for example, by a method using a card machine or a direct sheet method, and specifically by a nonwoven fabric manufacturing method such as resin bond, binder fiber blend, heat roll, and waterny drink. Can be manufactured.
Examples of the web forming method include a method of forming a web by opening the composite fiber using a card machine when short fibers such as staple fibers are used as the composite fiber. When long fibers such as continuous filaments are used as the composite fiber, the melt-spun composite fiber is transported to a high-speed air stream, and deposited and opened on a moving net to form a web (spun Bond method).
[0028]
As a method of forming a nonwoven fabric by heat-treating the formed web (thermal bond method), for example, the web is passed through a through air dryer and heated between the entanglement points of the constituent fibers of the web by hot air. There is a method of forming a large number of adhesion points by fusing. In this case, the temperature and supply amount of the hot air depends on the type of the constituent fibers of the web, the basis weight of the web, and the conveyance speed, but in general, the temperature of the hot air is preferably 140 to 170 ° C. Or it is preferable that a wind speed is 0.5-3 m / min.
Moreover, the heat embossing using a pair of embossing roll which consists of an engraving roll and a smooth roll is mentioned as another method of the said heat processing. In this case, hot embossing is performed by heating one or both of these two rolls. The heating temperature of the embossing roll is preferably 120 to 170 ° C. When the embossing roll is heated to a higher temperature, the web may adhere to the embossing roll.
As the engraving roll, for example, an iron roll having various patterns engraved on its surface can be used. On the other hand, a paper roll, a rubber roll, a silicon rubber roll, a urethane rubber roll, a metal roll, etc. can be used as the smooth roll. Examples of the pattern of the engraving roll include, for example, pins, dot dots, turtle shells, lattices, vertical stripes, horizontal stripes, stitches, patterns, and the like, and are not particularly limited to the patterns.
Although the linear pressure of the embossing roll at the time of the hot embossing depends on the basis weight and transport speed of the web, the heating temperature of the embossing roll, and the like, the general range is preferably 10 to 150 kg / cm.
[0029]
The stretchable elastic nonwoven fabric preferably has a stretch recovery rate of 20 to 100% when stretched by 20%, more preferably 60 to 100%. If the stretch recovery rate is less than 40%, for example, when the stretchable elastic nonwoven fabric is used for clothing or the like, the follow-up to the movement of the human body may be insufficient and the resistance may increase.
[0030]
It said stretchable elastic nonwoven preferably has a basis weight of 5 to 200 g / m ^2, and still more preferably from 15 to 80 g / m ^2. If the basis weight is less than 5 g / m ² , the elongation recovery rate may be small and insufficient, and if it exceeds 200 g / m ² , it is difficult to form a nonwoven fabric by the thermal bond method, which is disadvantageous in terms of cost. Therefore, it is preferable to be within the above range.
[0031]
The stretchable elastic nonwoven fabric preferably has a thickness under a load of 0.5 g / cm ² of 0.05 to 5 mm, and more preferably 0.2 to ² mm. If the thickness is less than 0.05 mm, the fiber density becomes high and the stretch properties may be insufficient. If the thickness exceeds 5 mm, the stretch elastic nonwoven fabric is practically used for clothing or the like. In order to give an uncomfortable feeling, it is preferable to be within the above range.
[0032]
Next, with reference to drawings, one form of the disposable diaper of this invention is demonstrated in detail.
Here, FIG. 1 is a partially broken plan view showing a back sheet side in one embodiment of the disposable diaper of the present invention, and FIG. 2 is an enlarged perspective view showing a fastening tape in the disposable diaper shown in FIG. FIG. 3 is an enlarged perspective view showing another embodiment of the fastening tape used in the present invention.
[0033]
The disposable diaper 1 of this embodiment shown in FIG. 1 comprises a liquid-permeable top sheet 2, a liquid-impermeable back sheet 3, and a liquid-retaining absorbent 4 interposed between both sheets 2 and 3. Fastening tape 10 for wearing a pair of diapers is disposed on left and right side edges B1 and B2 of the back side B.
Further, a landing tape 9 for fastening the fastening tape is provided at a substantially central portion of the abdominal side A.
[0034]
In addition, a solid guard 8 having a free end 8b on the inner side of the diaper, which is formed by fixing the leak-proof sheet 8a on the outer side of the diaper, is disposed on the top sheet 2. In addition, although a well-known thing can be especially used as said leak-proof sheet without a restriction | limiting in particular, A hydrophobic nonwoven fabric, the nonwoven fabric by which water-repellent treatment was performed, etc. are used preferably.
Such a structure is the same as that of the conventional disposable diaper, and each member can also be formed using a well-known material without a restriction | limiting in particular.
[0035]
The fastening tape 10 includes the stretchable elastic nonwoven fabric 16.
[0036]
More specifically, the fastening tape 10 is fixed to the tape main body 11 and the surface sheet 2 of the diaper, and the surface is made to be peelable, and the adhesive of the locking portion 13 is applied when not in use. A release tape (not shown) that protects the surface by contacting the surface.
Further, as shown in FIG. 1, the tape body 11 is joined to and fixedly attached to the back sheet 3, and is connected to the base end 12, and the elastic elastic nonwoven fabric 16 (FIG. 2). The elastic part 15 formed by the reference), the engaging part 13 connected to the elastic part 15 and coated with an adhesive on one surface (surface sheet side), and the engaging part 13 It consists of a knob 14 formed by folding the tip.
The structure of the fastening tape 10 will be described in more detail with reference to FIG. 2. The base end portion 12 and the stretchable portion 15 are integrally formed of the same material, that is, the stretchable elastic nonwoven fabric 16. The stretchable part 15 and the locking part 13 are connected via a joint part 18.
[0037]
Moreover, the said latching | locking part 13 is formed with the film sheet and adhesive which are used for the normal fastening tape.
Moreover, although the said junction part 18 is formed by joining the said expansion-contraction part 15 and the said latching | locking part 13 using a normal joining method without a restriction | limiting in particular, in this form, one end of the said expansion-contraction part 15 is used. And one end of the locking portion 13 are partially bonded by, for example, heat-sealing.
Further, the base end portion 12 may be joined to the back side portion by being partially bonded by heat fusion or the like, or may be joined by heat embossing or ultrasonic sealing. Also good.
[0038]
Moreover, the elastic members 20 and 30 are distribute | arranged also at the leg part 6 located in the waist part 5 located in a wearer's waist at the time of a wearer's waist, and the leg periphery, respectively. Further, also in the three-dimensional guard 8, an elastic member 40 is disposed at the free end 8b. The elastic member 40 is disposed so as to be covered with the leak-proof sheet 8a by folding the end edge side of the leak-proof sheet 8a into a tubular shape at the inner free end 8b of the diaper in the three-dimensional guard 8. .
[0039]
Since the disposable diaper of this embodiment is configured as described above, the locking part 13 of the tape body 11 can be extended to fasten the diaper, and has excellent fit and leakage prevention properties, Even if the fastening tape hits the wearer during wearing, the skin irritation is low.
[0040]
Next, with reference to FIG. 3, the other form of the fastening tape used for the disposable diaper of this invention is explained in full detail.
The fastening tape 10A of the form shown in FIG. 3 has a base end portion 12A that is wide, and is formed so that the stretchable portion 15A becomes wider toward the base end portion 12A, thereby fitting. Is further improved. In addition, all other points are the same as the fastening tape of the form shown in FIGS. 1 and 2 described above, and the above description is appropriately applied.
[0041]
In addition, the disposable diaper of this invention is not restrict | limited to the form shown in FIG. 1, A various change is possible in the range which does not deviate from the meaning of this invention.
Moreover, all the said fastening tape 10 may be formed with the said elastic elastic nonwoven fabric.
The fastening tape 10 includes a convex member or a concave member of a mechanical fastener on the surface side (diaper surface side of the diaper) as the locking means instead of the above-mentioned adhesive. You may do it. As the convex member or concave member used at this time, a normal convex member and concave member can be used without particular limitation. In addition, when the convex member is used as the locking means, the landing tape 9 is a concave member, and when the concave member is used as the locking means, the landing tape 9 is a convex member. is there.
[0042]
【The invention's effect】
The disposable diaper of the present invention has low skin irritation and excellent moldability.
[Brief description of the drawings]
FIG. 1 is a partially broken plan view showing a back sheet side in one embodiment of a disposable diaper of the present invention.
FIG. 2 is an enlarged perspective view schematically showing a fastening tape in the disposable diaper shown in FIG. 1;
FIG. 3 is an enlarged perspective view schematically showing another embodiment of a fastening tape used in the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Disposable diaper 2 Top sheet 3 Back sheet 4 Absorber 10 Fastening tape 11 Tape main body 12 Base end part 13 Locking part 14 Picking part

Claims (4)

It has a liquid-permeable top sheet, a liquid-impermeable back sheet, and a liquid-retaining absorber interposed between the two sheets, and a fastening tape for wearing a pair of diapers on the left and right side edges of the back side. In the deployment type disposable diaper where
Said fastening tape, hard Elastica tic component of crystalline polypropylene as a first component, a thermoplastic elastomer comprises a stretchable elastic nonwoven fabric made of stretchable elastic composite fibers to second component Ri Na,
It said stretchable elastic composite fibers, said first component is the sheath, a disposable diaper said second component and said sheath-core type composite fibers der Rukoto as core. It has a liquid-permeable top sheet, a liquid-impermeable back sheet, and a liquid-retaining absorber interposed between the two sheets, and a fastening tape for wearing a pair of diapers on the left and right side edges of the back side. In the deployment type disposable diaper where
Said fastening tape, hard Elastica tic component of crystalline polypropylene as a first component, a thermoplastic elastomer comprises a stretchable elastic nonwoven fabric made of stretchable elastic composite fibers to second component Ri Na,
The thermoplastic elastomer is a disposable diaper which a metallocene compound wherein the ethylene -α- olefin copolymer der Rukoto prepared as a catalyst. The disposable diaper according to claim 1 or 2 , wherein the fastening tape includes a convex member or a concave member of a mechanical fastener as a locking means. The disposable diaper according to any one of claims 1 to 3, wherein a content of the first component in the elastic elastic conjugate fiber is 5 to 70% by weight, and a content of the second component is 95 to 30% by weight. .

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