JP3964637B2 - Disposable diapers - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a disposable diaper.
[0002]
[Prior art]
The disposable diaper disclosed in Japanese Patent Application Laid-Open No. 63-256701 has an absorbent body between a surface nonwoven fabric that contacts the skin of the diaper wearer and a polyethylene sheet that contacts the clothing. In this absorbent body, the polymer layer and the pulp layer are in a laminated state, and immediately below the surface nonwoven fabric, a pulp layer and a layer of polymer powder having a slow absorption rate and strong gel strength are formed in order from top to bottom, Immediately above the polyethylene sheet, a pulp layer and a layer of polymer powder having a high absorption rate and low gel strength are formed in order from top to bottom.
[0003]
[Problems to be solved by the invention]
In the conventional diaper, since the pulp layer and the polymer powder layer having a low absorption rate are located in the vicinity of the wearer's skin, the urine absorbed in the pulp layer is placed in the polymer powder layer immediately below. It is not absorbed quickly and tends to stay in the vicinity of the skin as a result. In such diapers in which polymer powder having a slow absorption rate is arranged in the vicinity of the skin, a strong moist feeling is often given to the diaper wearer immediately after urination. When the disposable diaper is for adults in particular, since the amount of urination is large once, if the urine is not absorbed quickly, a strong moist feeling is given to the diaper wearer for a long time.
[0004]
The present invention relates to an improvement of a disposable diaper using superabsorbent polymer particles, and an object thereof is to provide a disposable diaper that does not give a strong moist feeling even after urination and can give a so-called dry feeling. .
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention is directed to the skin contact surface and the clothing contact surface, and the front waist area, the back waist area, and both areas in the length direction of the skin contact surface. The disposable diaper has a crotch region that has a body fluid-absorbing core inside the liquid-permeable surface sheet that forms the skin contact surface.
[0006]
In this disposable diaper, the features of the present invention are as follows. The core has a first absorbent layer, a second absorbent layer, and a third absorbent layer in the thickness direction of the core from the skin contact surface to the clothing contact surface, and the first absorbent layer is an upper ground pulp or consists intake Osamuzai consisting either of a mixture of upper fluff pulp and first superabsorbent polymer particles and the upper tissue paper, covering substantially the entirety of the absorbent upper tissue paper is in contact with the topsheet And the second absorbent layer is distributed only adjacent to each other to the extent that a gel block can be formed upon water absorption, and is formed only by the dense second superabsorbent polymer particles, and the third absorbent layer comprises the lower ground pulp and the The upper tissue paper is made of an absorbent material made of a mixture with the first superabsorbent polymer particles, and the lower tissue paper entirely covers the third absorbent layer and does not come into contact with the second absorbent layer. The widths of the first absorbent layer and the third absorbent layer are substantially the same in the crotch region and in the vicinity thereof, and the second absorbent layer is the first and third absorbent layers. 1/3 to 2/3 of the width of the first and third absorbent layers, and is positioned so as to be encased in the upper and lower tissue papers in the widthwise central portion of the first and third absorbent layers. While the polymer particles have a water absorption time of 30 seconds or more and a water retention ratio of 35 g / g or more, the second highly absorbent polymer particles have a water absorption time of 25 seconds or less and a water retention ratio of 35 g / g or less.
[0007]
[0008]
In this invention, the water absorption time of the superabsorbent polymer particles such as the first and second superabsorbent polymer particles is measured as follows. While stirring 50 g of 0.9% saline in a 100 ml beaker, 2 g of superabsorbent polymer particles are added thereto. Stirring is continued after the addition, and the time until the liquid level of the saline solution is flattened by the swollen superabsorbent polymer particles is measured, and the time is defined as the water absorption time.
[0009]
In the present invention, the water retention ratio of the superabsorbent polymer particles is measured as follows. About 1 g of superabsorbent polymer particles are immersed in 0.9% saline and left for 1 hour. Thereafter, the superabsorbent polymer particles are subjected to a dehydration treatment at 850 rpm (150 G) for 90 seconds using a centrifuge, and the weight after dehydration is determined. The ratio of the weight after dehydration with respect to the weight before immersion in the saline solution is determined and used as the water retention ratio.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The details of the disposable diaper according to the present invention will be described with reference to the accompanying drawings.
[0011]
FIG. 1 is a partially broken plan view of a disposable diaper 1. The diaper 1 is of an open type, and a liquid-permeable surface sheet 2 that forms a contact surface with respect to the skin of the wearer of the diaper 1 and a non-forming surface that forms a contact surface with respect to the wearer's clothes. It has a liquid-permeable back sheet 3 and a body fluid-absorbing core 4 interposed between both sheets 2 and 3. The front and back sheets 2 and 3 extend from the periphery of the core 4 and overlap each other, and are joined together to form front and rear end edge flaps 11 and 12 and side edge flaps 13. The diaper 1 has a front waistline region 6, a back waistline region 7, and a crotch region 8 positioned between both regions 6 and 7 in the length direction (vertical direction in the figure). A tape fastener 14 is attached to the side edge flap 13 in the surrounding area 7. In the front and rear end edge flaps 11 and 12 and the side edge flap 13 in the crotch region 8, the waist elastic members 15 and 16 and the leg elastic members 17 extend on at least one inner surface of the front and back sheets 2 and 3. It is attached in a state.
[0012]
FIG. 2 is a sectional view taken along line II-II in FIG. As is apparent by referring also to FIG. 1, the core 4 is formed in a so-called hourglass shape having a wide width in the front and rear waist regions 6 and 7 and a narrow width in the crotch region 8. The core 4 includes an upper absorbent layer 21 (hereinafter referred to as a first absorbent layer) near the top sheet 2, a lower absorbent layer 22 (hereinafter referred to as a third absorbent layer) near the back sheet, And an intermediate absorption layer 23 (hereinafter referred to as a second absorption layer) interposed between the intermediate absorption layers 22. The 1st absorption layer 21 and the 3rd absorption layer 22 have the same width, and are exhibiting the hourglass type. The second absorbent layer 23 has a width that is 1/3 to 2/3 of the width of the first and third absorbent layers 21 and 22 in the crotch region 8, and is substantially uniform in width and centered on the crotch region 8. It extends to the waist area 6 and the back waist area 7. However, the width of the second absorbent layer 23 in the front and rear waist regions 6 and 7 can be made wider or narrower than the width of the crotch region 8.
[0013]
The first absorbent layer 21 is composed of an upper pulverized pulp 26 or an aggregate 28 of mixed upper pulverized pulp 26 and first superabsorbent polymer particles 27, and an upper tissue paper 29. 28 has an upper surface 31 and a lower surface 32 and is covered with upper tissue paper. In the aggregate 28, the pulverized pulp 26 is used in a basis weight of 50 to 300 g / m ² , more preferably 150 to 250 g / m ² , and the first superabsorbent polymer particles 27 have a basis weight of 0 to 100 g / m ^2. m ² , more preferably in the range of 10 to 50 g / m ² . As the first superabsorbent polymer particles 27, those having a high water retention ratio of 35 g / g or more are used, and the polymer particles 27 have a long water absorption time of approximately 30 seconds or more .
[0014]
The third absorbent layer 22 is composed of an aggregate 34 of mixed lower pulverized pulp 33 and first superabsorbent polymer particles 27, and the aggregate 34 is covered with a lower tissue paper 36 for maintaining its shape. Has been. The third absorbent layer 22 is in contact with the back sheet 3 from above via the lower tissue paper 36. The lower pulverized pulp 33 is used in a basis weight of 150 to 350 g / m ² , more preferably 200 to 300 g / m ² , and the first superabsorbent polymer particle 27 has a basis weight of 40 to 200 g / m ² , more preferably It is used in the range of 60 to 150 g / ^{m 2.}
[0015]
The second absorbent layer 23 is formed only by the second superabsorbent polymer particles 42, and is located between the upper tissue paper 29 and the lower tissue paper 36. As described above, the second absorption layer 23 is sandwiched between the tissue papers 29 and 36 having good diffusibility, so that the supply of urine to the upper and lower surfaces of the absorption layer 23 is accelerated .
The second superabsorbent polymer particles 42 have a short water absorption time of 25 seconds or less, which has a low water holding capacity of approximately 35 g / g or less. The second superabsorbent polymer particles 42 are used in a basis weight of 50 to 200 g / m ² , more preferably 80 to 120 g / m ² . In the second absorbent layer 23, a large number of second superabsorbent polymer particles 42 are distributed and densely arranged so that adjacent particles 42 come into contact with each other to form a gel block when absorbing 5 to 10 times their own weight. It is preferable. Outside the both side edges of the second absorbent layer 23, the first absorbent layer 21 and the third absorbent layer 22 overlap with each other via the lower tissue paper 36.
[0016]
In the diaper 1 in which the core 4 is formed in this way, urine that has permeated through the top sheet 2 diffuses planarly in the upper tissue paper 29 of the first absorbent layer 21, and further through the upper pulverized pulp 26, the absorbent layer 21. Move downwards. The first superabsorbent polymer particles 27 contained in the first absorbent layer 21 have a slow absorption rate and do not immediately capture excreted urine. In the central portion in the width direction of the core 4, urine from the first absorption layer 21 is quickly captured by the second superabsorbent polymer particles 42 having a high absorption rate, the polymer particles 42 swell and come into contact with each other, and the gel block Start forming. By capturing the urine by the polymer particles 42, the upper part of the central portion of the core 4 is in a dry state. On both sides of the core 4, urine moves from the first absorption layer 21 to the third absorption layer 22, and further moves laterally in the third absorption layer 22 to below the second absorption layer 23. The both sides of the core 4 are in a dry state as urine moves downward while being absorbed by many upper and lower pulverized pulps 26 and 33. The urine absorbed in the pulverized pulps 26 and 33 is captured by the first superabsorbent polymer particles 27 as time passes.
[0017]
The second superabsorbent polymer particles 42 forming the core 4 have a fast water absorption rate of 25 seconds or less. However, the polymer particles having such properties are saturated in a short time, so that the repeated absorbability is poor. In general, the water retention ratio is low. For example, the water retention rate of the second superabsorbent polymer particles 42 having a water absorption rate of 25 seconds or less is approximately 35 g / g or less. Therefore, if the water-absorbing polymer particles of the core 4 are only such second superabsorbent polymer particles 42, a large amount of urine cannot be absorbed even if urine is rapidly absorbed, and the polymer particles 42 are When pressure is applied, urine that cannot be absorbed and is located around the superabsorbent polymer particles 42 is pushed out, and a so-called rewetting phenomenon occurs, giving the diaper wearer a wet feeling. However, the first superabsorbent polymer particles 27 having a slow absorption rate of 30 seconds or more generally have a high water retention ratio. For example, the water retention rate of the first superabsorbent polymer particles 27 having a water absorption speed of 30 seconds or more is approximately 35 g / g or more. In the core 4 in which the first and second superabsorbent polymer particles 27 and 42 are used together, body pressure acts on the core 4 immediately after urine is excreted by the cooperation of the polymer particles 27 and 42. Until such time, the surface of the core 4 can be kept dry for a long time, and the diaper 1 wearer is not given a wet feeling. In particular, when the second absorption layer 23 absorbs urine to form a gel block, even if the third absorption layer 22 located below the second absorption layer 23 receives body pressure and releases urine, It is possible to prevent urine from exuding to the surface of the core 4.
[0018]
The second absorption layer 23 acting in this way can capture urine from both the upper and lower surfaces by being sandwiched between the first absorption layer 21 and the third absorption layer 22. The basis weight of the second superabsorbent polymer particles 42 in the second absorbent layer 23 is that almost all of the second superabsorbent polymer particles 42 are consumed when the both surfaces are gel-blocked, and almost no urine is still present between the two surfaces. It is set so that nothing that is not absorbed remains.
[0019]
[0020]
[0021]
【The invention's effect】
The body fluid-absorbing core of the disposable diaper according to the present invention is a combination of the second superabsorbent polymer particles having a high water absorption rate but a low water retention rate, and the first superabsorbent polymer particles having a low water absorption rate but a high water retention rate. In addition, the second superabsorbent polymer particles are densely arranged near the skin contact surface in the crotch region of the diaper, and the first superabsorbent polymer particles are arranged below the second superabsorbent polymer particles. Even if urine is excreted, the diaper wearer does not give a strong moist feeling.
[Brief description of the drawings]
FIG. 1 is a partially broken plan view of a disposable diaper.
FIG. 2 is a cross-sectional view taken along the line II-II in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Disposable diaper 2 Top sheet 4 Core 6 Front waist area 7 Rear waist area 8 Inseam area 21 1st absorption layer (upper absorption layer)
22 3rd absorption layer (lower absorption layer)
23 Second absorption layer (intermediate absorption layer)
26 Upper ground pulp 27 First superabsorbent polymer particles 29 Upper tissue paper 33 Lower ground pulp 36 Lower tissue paper 42 Second superabsorbent polymer particles

Claims (1)

A liquid permeation having a skin contact surface and a clothing contact surface, and a front waistline region, a back waistline region, and a crotch region located between both regions in a length direction of the skin contact surface, and forming the skin contact surface In a disposable diaper in which a bodily fluid absorbent core is provided inside the adhesive surface sheet,
The core has a first absorbent layer, a second absorbent layer, and a third absorbent layer in the thickness direction of the core from the skin contact surface to the clothing contact surface, and the first absorbent layer is an upper ground pulp or consists intake Osamuzai consisting either of a mixture of upper fluff pulp and first superabsorbent polymer particles and the upper tissue paper, covering substantially the entirety of the absorbent upper tissue paper is in contact with the topsheet And the second absorbent layer is distributed only adjacent to each other to the extent that a gel block can be formed upon water absorption, and is formed only by the dense second superabsorbent polymer particles, and the third absorbent layer comprises the lower ground pulp and the The upper tissue paper is made of an absorbent material made of a mixture with the first superabsorbent polymer particles, and the lower tissue paper entirely covers the third absorbent layer and does not come into contact with the second absorbent layer. The widths of the first absorbent layer and the third absorbent layer are substantially the same in the crotch region and in the vicinity thereof, and the second absorbent layer is the first and third absorbent layers. 1/3 to 2/3 of the width of the first and third absorbent layers, and is positioned so as to be wrapped in the upper and lower tissue paper at the center in the width direction of the first and third absorption layers,
The first superabsorbent polymer particles have a water absorption time of 30 seconds or more and a water retention ratio of 35 g / g or more, while the second superabsorbent polymer particles have a water absorption time of 25 seconds or less and a water retention of 35 g / g or less. The disposable diaper characterized by having a magnification.

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