JP2021007515A - Absorbent article - Google Patents

Abstract

To provide an absorbent article that can maintain a good appearance without using highly absorbent polymers containing a component to prevent discoloration.SOLUTION: An absorbent article has an absorber 5 having an absorbent core 6 and a core wrap sheet 7, wherein the absorbent core 6 is composed of an aggregate of a highly absorbent polymer 67 and pulp fibers 68, the absorbent core 6 is divided in the thickness direction into a surface portion 61 located on the skin surface side, a rear portion 62 located on the non-skin surface side, and a thickness direction central portion 63 located between the surface portion 61 and the rear portion 62, and the thickness direction central portion 63 is a high-density layer of highly absorbent polymers in which the mass ratio of highly absorbent polymers 67 to pulp fibers 68 is greater than in the surface portion 61 and the rear portion 62.SELECTED DRAWING: Figure 3

Description

The present invention relates to absorbent articles.

Highly absorbent polymers (so-called SAP, surface-crosslinked polymer materials) used in absorbent articles such as diapers turn yellow or brown due to oxidation in a hot and humid environment, and are used in absorbent articles. The appearance may look deteriorated. Such a phenomenon is particularly likely to occur in subtropical and tropical regions such as Southeast Asia. Therefore, a technique has been proposed in which discoloration of a highly absorbent polymer is suppressed by using an antioxidant or the like to maintain a good appearance of the absorbent article.
For example, Patent Document 1 describes a technique using an acrylic acid or a quinhydronation inhibitor having a low content of hydroquinone, Patent Document 2 describes a technique using a reducing compound and a specific acid (salt), and Patent Document 3 describes it. Techniques using sulfinic acid derivatives are described respectively.
On the other hand, a technique for arranging a large amount of highly absorbent polymer at a specific site has also been proposed. For example, Patent Document 4 describes an absorbent article in which an absorber having a high content ratio of a polymer absorber on the front surface material side and a low content ratio of a polymer absorber on the back surface material side is interposed. Further, Patent Document 5 describes an absorber having an absorbent core having 50 parts by mass or more of a granular absorbent polymer in a predetermined range.

Japanese Unexamined Patent Publication No. 11-322846 Japanese Unexamined Patent Publication No. 2003-52742 Special Table 2006-521431 JP-A-2009-119154 JP-A-2018-47189

In the techniques described in Patent Documents 1 to 3, an expensive highly absorbent polymer containing a component that suppresses discoloration such as an antioxidant has to be used, and the price of the absorbent article becomes high.
In view of the above points, the present invention relates to an absorbent article capable of maintaining a good appearance without using a highly absorbent polymer containing a component that suppresses discoloration.

The present invention is an absorbent article comprising an absorbent core having an absorbent core and a core wrap sheet covering the outer periphery of the absorbent core, wherein the absorbent core is a highly absorbent polymer and pulp fiber. The absorbent core is composed of an aggregate, and the absorbent core is located between the front surface portion located on the skin surface side, the back surface portion located on the non-skin surface side, and the front surface portion and the back surface portion in the thickness direction. It is divided into a central portion, and the central portion in the thickness direction is an absorbent layer in which the mass ratio of the highly absorbent polymer to the pulp fibers is larger than that of the front surface portion and the back surface portion. Providing goods.

The absorbent article of the present invention can maintain a good appearance without using a highly absorbent polymer containing a component that suppresses discoloration.

It is a perspective view of the diaper which showed the preferable embodiment of the absorbent article which concerns on this invention. It is a partially cutaway development plan view schematically showing a state in which the diaper shown in FIG. 1 is broken at a side seal portion, developed and extended, and viewed from the skin surface side. FIG. 2 is a sectional view taken along line III-III of FIG. It is a top view which shows typically the absorbent core which the diaper of FIG. 2 has. (A) is a sectional view taken along line AA in FIG. 4, and (B) is a sectional view taken along line BB in FIG. FIG. 5 is a plan view schematically showing another preferred embodiment of the absorbent core of the diaper of FIG. 6 is a cross-sectional view schematically showing a state in which core wrap sheets on the skin surface side and the non-skin surface side are adhered to the slit portion of the absorbent core of FIG.

Hereinafter, a diaper as a preferred embodiment of the absorbent article of the present invention will be described below with reference to the drawings.

In the present invention, the side in contact with the skin of the wearer is referred to as the skin surface side or the skin contact surface side or the front surface side, and the opposite side is referred to as the non-skin surface side or the non-skin contact surface side or the back surface side. These are also used as terms indicating the relative positional relationship in the member composition of the absorbent article even for the member having no surface in contact with the wearer's skin. Further, the normal direction of the front surface or the back surface of the absorbent article is referred to as a thickness direction.

As shown in FIG. 1, the diaper 10 of the present embodiment has an absorbent main body 1 and an exterior body 2. The exterior body 2 has a front exterior body 21 and a rear exterior body 22 corresponding to the front side and the rear side of the wearer, respectively. The anterior side is the ventral side of the wearer, and the posterior side is the dorsal side of the wearer. The front exterior body 21 and the rear exterior body 22 are horizontally long, and their side edges are overlapped and joined at the side seal portion 11, forming an annular waist circumference portion 10D in the diaper 10. The portion of the absorbent body 1 extending from the exterior body 2 forms the intermediate portion 10C of the diaper 10. The diaper 10 has a waist opening 12 that is open above the waistline portion 10D, and a pair of leg openings 13 and 13 that are open on both the left and right sides of the intermediate portion 10C.

FIG. 2 shows a developed state in which the diaper 10 is broken at the side seal portions 11 and 11. Here, the unfolded state means a state in which each part is stretched to spread the absorbent article in a plane.
The diaper 10 is divided into a front side portion 10F, an intermediate portion 10C, and a rear side portion 10R in the deployed state. A horizontally long front exterior body 21 and a rear exterior body 22 are respectively arranged on the front side portion 10F and the rear side portion 10R. The vertically long absorbent body 1 is arranged on the skin surface side of the front exterior body 21 and the rear exterior body 22 so that the longitudinal direction thereof faces the front side portion 10F, the intermediate portion 10C, and the rear side portion 10R of the diaper 10. There is. In this arrangement, the absorbent body 1 has a longitudinal direction Y corresponding to the direction in which the front, middle and rear sides of the wearer are connected, and a width direction X orthogonal to the longitudinal direction Y. At the front and rear ends of the absorbent body 1 in the longitudinal direction Y, the front exterior body 21 and the rear exterior 22 on the non-skin surface side are each folded back and joined to the skin surface side of the absorbent body 1. As a result, the skin surface side and the non-skin surface side of the front and rear ends of the absorbent body 1 in the longitudinal direction Y are covered with the front exterior body 21 and the rear exterior body 22.

As shown in FIG. 3, the absorbent main body 1 constituting the diaper 10 includes a liquid-permeable front sheet 3 on the skin surface side, a leak-proof back sheet 4 on the non-skin surface side, and a front surface sheet 3 and a back surface sheet. It has a liquid-retaining absorber 5 arranged between and between 4. The absorber 5 has an absorbent core 6 composed of an aggregate of the highly absorbent polymer 67 and pulp fibers 68, and a core wrap sheet 7 that covers the outer periphery of the absorbent core 6. The core wrap sheet 7 is made of a hydrophilic material, for example, made of hydrophilic paper or non-woven fabric.

Further, in the present embodiment, a pair of side sheets 9 are provided on both sides of the absorbent body 1 in the longitudinal direction Y. A three-dimensional gathered portion 92 is formed by arranging an elastic member 91 elongated along the longitudinal direction Y at the inner end of the side sheet 9 in the width direction X. Further, the leg gather portion 94 is formed by arranging an elastic member 93 elongated along the longitudinal direction Y at the outer end portion of the side sheet 9 in the width direction X. Further, in the absorbent main body 1 of the present embodiment, the exterior non-woven fabric 48 is arranged on the non-skin surface side of the back sheet 4.

As shown in FIG. 2, the absorbent core 6 has a longitudinal direction Y and a width direction X orthogonal to the longitudinal direction, similarly to the absorbent body 1. As shown in FIGS. 2 and 3, the core wrap sheet 7 extends in the width direction X while covering the entire longitudinal direction Y of the absorbent core 6 on the skin surface side, both sides, and non-skin of the absorbent core 6. It is wound while covering the surface side (outer circumference). The ends of the wound core wrap sheet 7 in the width direction X are laminated with each other to form a laminated portion 75 over the entire length of the absorbent core 6 in the longitudinal direction Y. In FIG. 3, one laminated portion 75 of the core wrap sheet 7 is arranged on the non-skin surface side of the absorbent core 6, but the present invention is not limited to this. For example, it may be arranged on the skin surface side, or two or more may be arranged on the non-skin surface side or the skin surface side. From the viewpoint of liquid absorption, it is preferable that one laminated portion 75 of the core wrap sheet 7 is arranged on the non-skin surface side of the absorbent core 6.

As shown in FIG. 4, the absorbent core 6 is divided into three equal parts in the longitudinal direction Y into a front portion F, an intermediate portion C, and a rear portion R. The absorbable core 6 has a liquid receiving region Q that directly receives excrement liquid such as urine. In the diaper 10, the liquid receiving region Q is a region within 3.5 cm in the left and right width directions from the line S1 that bisects the length in the width direction X, and divides the length in the longitudinal direction Y into two equal parts. It is a region within 8 cm in the front side F direction from the line M1.
In the absorbent article of the present invention, the division positions of the front portion F, the intermediate portion C, and the rear portion R and the liquid receiving region Q are appropriately set according to the type of the absorbent article and the like. For example, when the absorbent article of the present invention is a sanitary napkin for daytime, the front part F, the middle part C and the rear part R are classified in the same manner as in the case of the above diaper 10, and the receiving area Q is in the middle. The portion C is a region within 2.5 cm in the left-right width direction from the line that divides the length of the intermediate portion C in the width direction X into two equal parts. When the absorbent article of the present invention is provided with a wide rear flap covering the buttocks such as for night use, it is divided into four equal parts in the longitudinal direction Y, the first division is the front portion F, the second division is the middle portion C, and the rest is the rear portion. It becomes part R. In this case, the liquid receiving region Q is the intermediate portion C and is within 2.5 cm in the left-right width direction from the line that bisects the length of the intermediate portion C in the width direction X. When the absorbent article of the present invention is a urine absorbing pad or an incontinence pad, it is set in the same manner as the diaper 10.

As shown in FIG. 5A, the absorbent core 6 has a front surface portion 61 located on the skin surface side, a back surface portion 62 located on the non-skin surface side, and a front surface portion 61 and a back surface portion 62 in the thickness direction. It is divided into a central portion 63 in the thickness direction located between the two. This division is made by dividing the absorbent core 6 into three equal parts in the thickness direction.

The central portion 63 in the thickness direction of the absorbent core 6 is a high-density polymer layer having a larger mass ratio of the high-absorbent polymer 67 to the pulp fibers 68 than the front surface portion 61 and the back surface portion 62. The highly absorbent polymer high-density layer may be located in a part of the central portion 63 in the thickness direction, but is preferably located in the entire plane region of the central portion 63 in the thickness direction. In this way, a large number of highly absorbent polymers 67 are arranged inside the absorbent core 6, and the highly absorbent polymers 67 contained in the absorbent core 6 are unevenly distributed. As a result, the highly absorbent polymer 67 inside is less likely to come into contact with air, and discoloration due to oxidation can be suppressed. Further, the high density of the highly absorbent polymer 67 can suppress the rate of discoloration. In addition, since the front surface portion 61 and the back surface portion 62 are layers having more pulp fibers 68 than the central portion 63 in the thickness direction, even if the highly absorbent polymer 67 inside is discolored, the color is discolored from the outside of the diaper 10. Is hard to see and the good appearance of the diaper 10 can be maintained. The high-density polymer layer formed by the central portion 63 in the thickness direction may be a single layer or a plurality of layers as long as it is located in a portion of the absorbent core 6 which is divided into three equal thicknesses.

In the central portion 63 in the thickness direction, the mass ratio of the highly absorbent polymer 67 to the pulp fiber 68 suppresses the discoloration of the highly absorbent polymer 67 and makes it difficult to see the discoloration from the outside of the diaper 10, while improving the absorbency of the absorber 5. From the viewpoint of holding, 1.0 or more is preferable, 1.25 or more is more preferable, and 1.5 or more is further preferable. Further, in the central portion 63 in the thickness direction, the mass ratio of the highly absorbent polymer 67 to the pulp fiber 68 is preferably 2.0 or less from the viewpoint of not deteriorating the liquid return property of the absorber 5 when pressurized, preferably 1.8 or less. The following is more preferable, and 1.6 or less is further preferable. Specifically, the mass ratio of the highly absorbent polymer 67 to the pulp fiber 68 is preferably 1.0 or more and 2.0 or less, more preferably 1.25 or more and 1.8 or less in the central portion 63 in the thickness direction. More preferably, it is 5.5 or more and 1.6 or less.

In the front surface portion 61 and the back surface portion 62, the mass ratio of the highly absorbent polymer 67 to the pulp fiber 68 is preferably 0.25 or more, preferably 0.38, from the viewpoint of not deteriorating the liquid return property when the absorber 5 is pressurized. The above is more preferable, and 0.4 or more is further preferable. Further, in the front surface portion 61 and the back surface portion 62, the mass ratio of the highly absorbent polymer 67 to the pulp fiber 68 is 0.75 or less from the viewpoint of making it difficult to see the discoloration of the highly absorbent polymer 67 inside from the outside of the diaper 10. Is preferable, 0.63 or less is more preferable, and 0.5 or less is further preferable. Specifically, the mass ratio of the highly absorbent polymer 67 to the pulp fiber 68 is preferably 0.25 or more and 0.75 or less, and more preferably 0.38 or more and 0.63 or less in the front surface portion 61 and the back surface portion 62. , 0.4 or more and 0.5 or less is more preferable.

The mass ratio of the highly absorbent polymer 67 to the pulp fiber 68 in the central portion 63 in the thickness direction is 1.3 times or more the mass ratio of the highly absorbent polymer 67 to the pulp fiber 68 in the front surface portion 61 and the back surface portion 62. It is preferable, 2.0 times or more is more preferable, and 3.0 times or more is further preferable. As a result, it is possible to more reliably achieve both the suppression of discoloration of the highly absorbent polymer 67 to make the discoloration difficult to see from the outside of the diaper 10 and the retention of the absorbency of the absorber 5. Further, the mass ratio of the highly absorbent polymer 67 to the pulp fiber 68 in the central portion 63 in the thickness direction is the mass ratio of the highly absorbent polymer 67 to the pulp fiber 68 in the front surface portion 61 and the back surface portion 62 of the absorber 5. From the viewpoint of not deteriorating the liquid return property at the time of pressurization, 8 times or less is preferable, 5 times or less is more preferable, and 4 times or less is further preferable.
Specifically, the mass ratio of the highly absorbent polymer 67 to the pulp fiber 68 in the central portion 63 in the thickness direction is 1 with respect to the mass ratio of the highly absorbent polymer 67 to the pulp fiber 68 in the front surface portion 61 and the back surface portion 62. It is preferably 3 times or more and 8 times or less, more preferably 2.0 times or more and 5 times or less, and further preferably 3.0 times or more and 4 times or less.

(Method of measuring the mass ratio of the highly absorbent polymer 67 to the pulp fiber 68)
First, while observing the cross section of the measurement target portion of the absorbent core 6 with a microscope, the cross section is divided into three equal parts in the thickness direction, and each portion of the front surface portion 61, the central portion 63 in the thickness direction, and the back surface portion 62 is collected.
For each of the collected sites, each of the mixture of the superabsorbent polymer 67 and the pulp fiber 68 was quantified based on the method for quantifying the fiber and / or the water-absorbent polymer described in Japanese Patent No. 4225821, and the high absorption to the pulp fiber 68 was obtained. The mass ratio of the sex polymer 67 is calculated.
Specifically, after measuring the mass of each of the collected parts, the high molecular weight of the high absorption polymer 67 is reduced at each part. The molecular weight of the highly absorbent polymer 67 can be reduced by irradiation with ultraviolet rays. At that time, a mixture of the highly absorbent polymer 67 and the pulp fiber 68 of each of the collected parts is placed in a mesh bag or the like and immersed in an aqueous solution containing ascorbic acid and riboflavin. After the highly absorbent polymer is swollen by immersion, the mesh bag is taken out from the aqueous solution and irradiated with the above ultraviolet rays to reduce the molecular weight of the highly absorbent polymer 67. Next, the components produced by the reduction in molecular weight are removed by washing with water. After thoroughly washing the removed mesh bag with water, it is dehydrated and dried to measure the mass. The mass of the pulp fiber 68 is calculated by subtracting the mass of the mesh bag alone from the measured mass, and the mass of the pulp fiber 68 is subtracted from the mass of each part measured first to obtain the mass of the highly absorbent polymer 67. Based on these, the mass ratio of the highly absorbent polymer 68 to the pulp fiber 68 at each site is calculated. The average value of the mass ratio obtained by performing the above measurement three times is taken as the mass ratio at each part of the front surface portion 61, the central portion 63 in the thickness direction, and the back surface portion 62.

As an example of a method of forming the central portion 63 in the thickness direction of the absorbent core 6 as a high-density layer of a highly absorbent polymer, a SAP duct into which the highly absorbent polymer 67 (SAP) is charged is provided below in the absorbing core manufacturing apparatus. It is conceivable to devise as follows.
First, as the above-mentioned manufacturing apparatus, a rotating drum provided with a recess for integration on the outer peripheral surface, and a manufacturing apparatus provided with a fiber material duct for supplying the fiber material by placing the rotating drum on an air stream are used. In the manufacturing apparatus, a first SAP duct and a second SAP duct for supplying the highly absorbent polymer 67 (SAP) are installed in the fiber material duct. The first SAP duct is installed on the upstream side of the pulp fiber 68 supply line with respect to the second SAP duct.
In the manufacturing apparatus, the mass ratio of the highly absorbent polymer 67 charged from the first SAP duct and the second SAP duct can be appropriately set to control the position where the highly absorbent polymer is blended at a high density. For example, if the mass of the highly absorbent polymer 67 charged from the first SAP duct is larger than the mass of the highly absorbent polymer 67 charged from the second SAP duct, the thickness is larger than that of the surface portion 61 of the absorbent core 6. A large amount of the highly absorbent polymer 67 is blended on the side of the central portion 63 in the direction.
Further, the position where the highly absorbent polymer is blended at a high density can be controlled by appropriately setting the insertion depth of the duct. For example, as the insertion depth of the duct is increased, a larger amount of the highly absorbent polymer is blended on the central portion 63 side in the thickness direction than the surface portion 61 of the absorbent core 6.
In this way, by appropriately setting the number of SAP ducts, the mass of the highly absorbent polymer 67 charged from the SAP ducts, and the insertion depth of the SAP ducts, the central portion 63 in the thickness direction of the absorbent core 6 is set to the height of the highly absorbent polymer. It can be formed as a density layer.

In the diaper 10, it is preferable that a member having a colored portion is arranged on at least one side of the absorbent core 6 on the skin surface side and the non-skin surface side. As a result, the discoloration of the highly absorbent polymer 67 can be made less noticeable from the outside of the diaper 10. From the viewpoint of maintaining a good appearance during wearing, the member having the colored portion is more preferably on the non-skin surface side of the absorbent core 6, and may be on both the skin surface side and the non-skin surface side. More preferred. When a member having a colored portion is arranged on both the skin surface side and the non-skin surface side, discoloration of the highly absorbent polymer 67 is less noticeable on both sides of the diaper before, during, and after wearing. be able to.

Examples of the member having a colored portion on the skin surface side of the absorbent core 6 include a core wrap sheet 7 and a surface sheet 3. Further, when there is an intermediate sheet (not shown) between the surface sheet 1 and the core wrap sheet 7, the intermediate sheet is also included in the member on the skin surface side of the absorbent core 6. Examples of the member having a colored portion on the non-skin surface side of the absorbent core 6 include a core wrap sheet 7, a back surface sheet 4, and an exterior nonwoven fabric 48. Further, with respect to the front exterior body 21 and the rear exterior body 22, the portion folded back toward the skin surface side of the absorbent body 1 becomes a member on the skin surface side of the absorbent core 6, and the non-skin surface side of the absorbent body 1 The portion arranged on the non-skin surface side of the absorbent core 6 is a member.

The "colored portion" is a portion where a colorant is applied to a member, and may be a portion colored with a certain pattern or a solid coated portion. Further, the colored portion may indicate a character, a pattern, or the like. It is preferable that the "colored portion" is colored in a region of 10% or more of the area of the member.
The "color" in the colored portion is not limited to a chromatic color, and may be an achromatic color. This "color" is a color darker than the color of the discolored high-absorbent polymer 67 (for example, yellow or brown) or a discolored color from the viewpoint of making the discoloration of the high-absorbent polymer 67 in the absorbent core 6 less noticeable. Complementary colors are preferred. Specifically, green, blue, and purple are preferable.

The position of the colored portion preferably overlaps with the positions of the ends 6E and 6E of the absorbent core 6 in the longitudinal direction Y in a plan view. As a result, the highly absorbent polymer 67 moves from the inside of the absorbent core 6, for example, the central portion 63 in the thickness direction, which is the high density layer of the highly absorbent polymer, to the ends 6E and 6E having less pulp fibers 68. Even if they collect, the discoloration of the highly absorbent polymer 67 can be obscured from the outside. When an impact is applied during the process of manufacturing or transporting the diaper 10, the highly absorbent polymer 67 may move inside the absorbent core 6 and reach the ends 6E and 6E of the absorbent core 6. In particular, in the present embodiment, since the central portion 63 in the thickness direction of the absorbent core 6 is a high-density layer of the highly absorbent polymer, the highly absorbent polymer 67 is more easily moved to the end portion 6E. Therefore, if the end portion of the absorbent core 6 is hidden by the colored portion, the highly absorbent polymer 67 that has moved to the end portion of the absorbent core 6 becomes difficult to see, which is preferable. In particular, from the viewpoint of effectively obscuring the discolored highly absorbent polymer 67, the colored portion of the back sheet 4 is a solid coating portion of the colorant, and the position of the colored portion is the end portion 6E of the absorbent core 6. It is more preferable that the position of 6E overlaps with the position in a plan view.

In a plan view of the absorbent core 6, as shown in FIG. 4, it is preferable that the high basis weight region 6H and the low basis weight region 6L having a basis weight lower than the high basis weight area 6H are arranged. The basis weight of the high basis weight region 6H and the low basis weight region 6L is a basis weight including both the highly absorbent polymer 67 and the pulp fiber 68 constituting the absorbent core 6.
When the plane region of the absorbent core 6 is divided into the above-mentioned front portion F, the intermediate portion C including the liquid receiving region Q, and the rear portion R in the longitudinal direction Y, the high basis weight region 6H is at least the intermediate portion C. The liquid receiving region Q is preferably included, and the low basis weight region 6L preferably includes at least the rear portion R.
When the high basis weight region 6H "includes at least the liquid receiving region Q of the intermediate portion C", the high basis weight region 6H includes the liquid receiving region Q of the intermediate portion C, and may further include other regions. Means that. For example, the high basis weight region 6H may include the whole or a part of the intermediate portion C, and may include a part of any one of the front portion F and the rear portion R in addition to the intermediate portion C. The high basis weight region 6H preferably includes at least a part of the front portion F in addition to the intermediate portion C, and more preferably includes the entire intermediate portion C and the front side portion F. The phrase "the low basis weight region 6L includes at least the rear portion R" means that the low basis weight region 6L includes the rear portion C and may further include other regions, for example, the intermediate portion C. It means that it may contain a part. When viewed along the width direction X, it is preferable that the high basis weight region 6H has the same basis weight in all the portions (excluding the slit portion 8 described later). Further, when viewed along the width direction X, it is preferable that the low basis weight region 6L has the same basis weight in all the portions (excluding the slit portion 8 described later).

As shown in FIG. 5B, the high basis weight region 6H and the low basis weight area 6L include the entire thickness of the absorbent core 6 in each plane region, that is, the front surface portion 61, the center portion 63 in the thickness direction, and the back surface portion. The entire part 62 is included. Since the high basis weight region 6H includes at least the liquid receiving region Q as described above, the absorption capacity of the absorbent core 6 in the region where the liquid receiving amount is large is increased. As a result, the above-mentioned central portion 63 in the thickness direction is made into a high-density layer of the highly absorbent polymer to make it difficult to see the discoloration of the highly absorbent polymer 67 from the outside, and at the same time, the absorption capacity around the liquid receiving region Q is increased to get wet. Backing (return of absorbed liquid to the skin side) can be suppressed. Further, due to the uneven distribution of the highly absorbent polymer 67 as described above, it is possible to suppress an increase in the amount of the highly absorbent polymer 67 while ensuring the absorption capacity and make the discoloration of the highly absorbent polymer 67 less noticeable. In addition, the degree of swelling during liquid absorption in the low basis weight region L can be suppressed, and the pressure on the wearer's lumbar region can be suppressed. The high basis weight region 6H and the low basis weight region 6L can be measured by the same method as described above (method for measuring the mass ratio of the highly absorbent polymer 67 to the pulp fiber 68).

From the viewpoint of making the above action more remarkable, the basis weight of the high basis weight region 6H is preferably 120% or more, more preferably 140% or more, based on the basis weight of the low basis weight region 6L. preferable. Further, the basis weight of the high basis weight region 6H is preferably 250% or less, more preferably 230% or less, with respect to the basis weight of the low basis weight area 6L. Specifically, the basis weight of the high basis weight region 6H is preferably 120% or more and 250% or less, and more preferably 140% or more and 230% or less with respect to the basis weight of the low basis weight area 6L. ..
Within the range of the ratio of the basis weight of the high basis weight region 6H to the basis weight of the low basis weight area 6L, the basis weight of the high basis weight area 6H is preferably 150 g / m ² or more, preferably 200 g / m ^2. The above is more preferable, and 250 g / m ² or more is further preferable. Further, the basis weight of the high basis weight region 6H is preferably 900 g / m ² or less, more preferably 850 g / m ² or less, and further preferably 800 g / m ² or less. Specifically, the basis weight of the high basis weight region 6H is preferably 150 g / m ² or more and 900 g / m ² or less, more preferably 200 g / m ² or more and 850 g / m ² or less, and 250 g / m. ^{It is} more preferably ² or more and 800 g / m ² or less.

Further, within the range of the ratio of the basis weight of the high basis weight region 6H to the basis weight of the low basis weight area 6L, the basis weight of the low basis weight area 6L is preferably 100 g / m ² or more, preferably 150 g / m. more preferably m ² or more, further preferably 200 g / ^{m 2} or more. The basis weight of the low basis weight region 6L is preferably not more than 600 g / ^{m 2,} and still more preferably more preferably 550 g / ^{m 2} or less, 500 g / ^{m 2} or less. Specifically, the basis weight of the low basis weight region 6L is preferably 100 g / m ² or more and 600 g / m ² or less, more preferably 150 g / m ² or more and 550 g / m ² or less, and 200 g / m. ^{It is} more preferably ² or more and 500 g / m ² or less.

Further, it is preferable that the magnitude relationship between the basis weight of the high basis weight region 6H and the basis weight of the low basis weight region 6L also applies to the magnitude relationship of the basis weight of the highly absorbent polymer 67 and the pulp fiber 68. That is, the basis weight of the highly absorbent polymer 67 constituting the high basis weight region 6H is preferably higher than the basis weight of the high absorption polymer 67 constituting the low basis weight region 6L. Further, the basis weight of the pulp fiber 68 constituting the high basis weight region 6H is preferably higher than the basis weight of the pulp fiber 68 constituting the low basis weight region 6L.

Further, from the viewpoint of making the above action more remarkable, the length of the high basis weight region 6H in the longitudinal direction Y of the absorbent core 6 is preferably 50% or more of the total length of the absorbent core 6. It is more preferably 60% or more, and further preferably 70% or more. Further, in the longitudinal direction Y of the absorbent core 6, the length of the high basis weight region 6H is preferably 90% or less, more preferably 85% or less, and 80% of the total length of the absorbent core 6. The following is more preferable. Specifically, in the longitudinal direction Y of the absorbent core 6, the length of the high basis weight region 6H is preferably 50% or more and 90% or less, and 60% or more and 85% or less of the total length of the absorbent core 6. It is more preferable that it is 70% or more and 80% or less.
From the viewpoint of making the above action more remarkable, the length of the low basis weight region 6L in the longitudinal direction Y of the absorbent core 6 is preferably 10% or more, preferably 15% or more of the total length of the absorbent core 6. The above is more preferable, and 20% or more is further preferable. Further, in the longitudinal direction Y of the absorbent core 6, the length of the low basis weight region 6L is preferably 50% or less, more preferably 40% or less, and 30% of the total length of the absorbent core 6. The following is more preferable. Specifically, in the longitudinal direction Y of the absorbent core 6, the length of the low basis weight region 6L is preferably 10% or more and 50% or less, and 15% or more and 40% or less of the total length of the absorbent core 6. It is more preferable that it is 20% or more and 30% or less.

The difference in thickness due to the difference in basis weight may or may not occur between the high basis weight region 6H and the low basis weight region 6L. Further, there may or may not be a difference in the mass ratio between the high absorbent polymer 67 and the pulp fiber 68 between the high basis weight region 6H and the low basis weight region 6L.

The high basis weight region 6H and the low basis weight area 6L as described above are the low basis weight among the breathable members constituting the bottom of the accumulation recesses in the accumulation recesses arranged on the outer peripheral surface of the rotating drum described above. It can be manufactured by making the portion to be the region 6H low air permeability.

Further, a member having the above-mentioned colored portion is arranged on the non-skin surface side of the absorbent core 6, and the high basis weight region 6H and the position of the colored portion may overlap in the plan view of the absorbent core 6. preferable. As a result, the discoloration of the highly absorbent polymer 67 can be made more difficult to see from the outside while increasing the absorption capacity around the liquid receiving region Q and suppressing wetback. From the same viewpoint, the overlap between the position of the high basis weight region 6H and the position of the colored portion preferably occupies 10% or more of the area of the high basis weight region 6H.

In the present embodiment, as shown in FIG. 6, it is preferable that the slit portion 8 is arranged in the absorbent core 6. The slit portion 8 is a space portion formed in the absorbent core 6 in the thickness direction from the skin surface side in which the amount of pulp fibers 68 is smaller than that of the surroundings. The slit portion 8 may be a notched portion or a groove having a predetermined width. At the position where the slit portion 8 is arranged, the excrement liquid easily permeates in the thickness direction of the absorbent core 6. That is, the excrement liquid easily reaches the central portion 63 in the thickness direction formed of the highly absorbent polymer high-density layer. As a result, the diaper 10 can be improved in quick liquid absorption retention and wetback prevention. That is, the rapid improvement of liquid absorption retention and wetback prevention is realized at the same time as making the discoloration of the highly absorbent polymer 67 less noticeable by forming the central portion 63 in the thickness direction into a high-density layer of the highly absorbent polymer. it can.

From the viewpoint of enhancing the liquid absorption retention and the wetback prevention property, the slit portion 8 preferably has a depth of reaching the central portion 63 in the thickness direction from the skin surface side of the absorbent core 6. It is more preferable that the through hole is from the skin surface side to the non-skin surface side of 6.
In addition, the slit portion 8 is preferably located in the liquid receiving region Q of the absorbent core 6 from the same viewpoint as described above.

In FIG. 6, the slit portions 8 have a length extending from the liquid receiving region Q to the front and back in the longitudinal direction Y, and three slit portions 8 are arranged side by side in the width direction X. The arrangement and number of the slit portions 8 are not limited to this, but the embodiment shown in FIG. 6 is preferable from the viewpoint of enhancing the liquid absorption retention and the wetback prevention property.

When there are a plurality of slit portions 8, the widths of the slit portions 8 (the groove width and the length in the width direction X) may be the same as or different from each other. When the width of each slit portion 8 is the same, the excrement liquid can be easily diffused uniformly and quickly in the absorbent core 6. This is preferable because a wider area of the absorbent core 6 can be utilized for liquid absorption. From the viewpoint of making this action more remarkable, the width of each slit portion 8 is preferably 1 mm or more, and more preferably 3 mm or more. Further, the width of each slit portion 8 is preferably 20 mm or less, more preferably 15 mm or less. Specifically, the width of each slit portion 8 is preferably 1 mm or more and 20 mm or less, and more preferably 3 mm or more and 15 mm or less. Even when the widths of the slit portions 8 are different from each other, it is preferable that the widths of the slit portions 8 are within the above range.

When there are a plurality of slit portions 8, the lengths of the slit portions 8 (the length in the longitudinal direction Y) may be the same as or different from each other. When the lengths of the slit portions 8 are the same, the excrement liquid can be easily diffused uniformly and quickly in the absorbent core 6. This is preferable because a wider area of the absorbent core 6 can be utilized for liquid absorption. From the viewpoint of making this action more remarkable, the length of each slit portion 8 is preferably 50 mm or more, more preferably 100 mm or more. Further, the length of each slit portion 8 is preferably 350 mm or less, more preferably 300 mm or less. Specifically, the length of each slit portion 8 is preferably 50 mm or more and 350 mm or less, and more preferably 100 mm or more and 300 mm or less. Even when the lengths of the slit portions 8 are different from each other, it is preferable that the lengths of the slit portions 8 are within the above range.

When the lengths of the slit portions 8 are the same, the positions of the front end F-side ends T1 of the slit portions 8 may be the same or different from each other. Similarly, the positions of the rear end R-side ends T2 of each slit 8 may be the same or different from each other. In FIG. 6, the positions of the ends T1 on the front F side of each slit 8 are the same, and the positions of the ends T2 on the rear R side of each slit 8 are the same.

It is preferable that each slit portion 8 is absent in the rear portion R. Further, the position of the end portion T2 on the rear portion R side of each slit portion 8 is preferably located on the front portion F side of the boundary position T3 between the low basis weight region 6L and the high basis weight region 6H described above. As a result, it is possible to balance the liquid absorption capacity of the absorbent core 6, the liquid diffusibility of the absorbent core 6, and the good wearing feeling of the diaper 10. In particular, the separation distance between the end portion T2 on the rear portion R side of each slit portion 8 and the boundary position T3 between the low basis weight region 6L and the high basis weight region 6H is preferably 5 mm or more, more preferably 10 mm or more. It is preferable, 50 mm or less is preferable, and 45 mm or less is more preferable. Specifically, the separation distance between the end portion T2 on the rear portion R side of each slit portion 8 and the boundary position T3 between the low basis weight region 6L and the high basis weight region 6H is preferably 5 mm or more and 50 mm or less. More preferably, it is 10 mm or more and 45 mm or less. As a result, the diffusion of the liquid in the high basis weight region 6H becomes more likely to occur. In addition, the absorbent core 6 is easily bent and deformed, and the wearing feeling of the diaper 10 is further improved.

In particular, if each slit portion 8 is absent on the rear R side of the absorbent core 6 from the position corresponding to the wearer's stool excretion portion, the excreted stool adheres to the wearer's skin. It is preferable because it becomes difficult. “Non-existent” on the rear R side means that the positions of the ends T2 on the rear R side of all the slits 8 are biased toward the front F from the positions corresponding to the stool excretion portion of the wearer. Say.

In addition to the method of making a notch in the absorbent core 6, the slit portion 8 as described above is non-breathable in a portion to be a slit portion 8 in the accumulation recess arranged on the outer peripheral surface of the rotating drum described above. It can be manufactured by providing the convex portion of.

Further, it is preferable that the position of the colored portion described above overlaps with the position of the slit portion 8 in a plan view. In general, the highly absorbent polymer 67 inside the absorbent core 6 tends to fall off (or leak) into the space of the slit portion 8. In particular, in the diaper 10, since the central portion 63 of the absorbent core 6 in the thickness direction is formed of a high-density layer of a highly absorbent polymer, it is more likely to fall off. On the other hand, since the position of the slit portion 8 and the position of the colored portion overlap in a plan view, even if the highly absorbent polymer 67 that has fallen off to the slit portion 8 is discolored, it becomes difficult to see from the outside of the diaper 10. That is, the highly absorbent polymer high-density layer, the slit portion 8 and the colored portion in the central portion 63 in the thickness direction make it difficult to see the discoloration of the highly absorbent polymer 67 from the outside of the diaper 10 and improve the absorption performance at the same time. It can be further enhanced.
In particular, from the viewpoint of effectively obscuring the discolored highly absorbent polymer 67, the colored portion of the non-skin surface side member (for example, the back surface sheet 4) of the absorbent core 6 is designated as a solid coating portion of the colorant. It is preferable that the position of the colored portion overlaps with the position of the slit portion 8 of the absorbent core 6 in a plan view.

It is preferable that the slit portion 8 is a through hole because the drawability of the excrement liquid is enhanced. In this case, regarding the core wrap sheet 7 that covers the outer periphery of the absorbent core 6, as shown in FIG. 7, the core wrap sheets 7 arranged on the skin surface side and the non-skin surface side of the absorbent core 6 are arranged (skin surface). It is preferable that the side core wrap 71 and the non-skin surface side core wrap sheet 72) are adhered at the position of the slit portion 8. That is, it is preferable that the skin surface side core wrap sheet 71 and the non-skin surface side core wrap sheet 72 enter the slit portion 8 from both side surfaces of the absorbent core 6 and are adhered to each other. It is more preferable that this adhesion is not peeled off even if it gets wet with the excrement liquid. As a result, the highly absorbent polymer 67 is less likely to move to the position of the slit of the absorber 5, and the discolored highly absorbent polymer 67 is less likely to be seen from the outside. The core wrap sheets 71 and 72 can be adhered to each other by various methods for realizing the above actions.

As described above, the core wrap sheet 7 extends in the width direction X while covering the entire longitudinal direction Y of the absorbent core 6, and is wound while covering the outer periphery of the absorbent core 6. The ends of the wound core wrap sheet 7 are laminated. In the portion where the core wrap sheets 7 are laminated, that is, the laminated portion 75, the thickness of the sheet is relatively increased by the lamination, and the discoloration of the highly absorbent polymer 67 inside the absorbent core 6 is made difficult to see. From this viewpoint, it is preferable that the position where a large amount of the highly absorbent polymer 67 is present and the position of the portion where the core wrap sheets 7 are laminated (laminated portion 75) overlap in a plan view. Here, the position where the high-absorptive polymer 67 is abundant is either or both of the above-mentioned high-absorptive polymer high-density layer, the central portion 63 in the thickness direction and the high basis weight region 6H in the plane direction. Means position.

Further, the absorbent core 6 preferably has a compressed portion (not shown) formed by applying a certain amount of compression in the thickness direction by embossing or the like from the viewpoint of suppressing the movement or falling off of the highly absorbent polymer 67. In the compressed portion, the pulp fiber 68 is compressed, which makes it easy to restrain the movement of the highly absorbent polymer 67. As long as this action is achieved, the depth of the compression portion can be appropriately set, and may be a depth that reaches the central portion 63 in the thickness direction of the absorbent core 6. From the viewpoint of preventing the absorbability of the highly absorbent polymer 67 from being hindered by compression, the depth of the compressed portion does not reach the central portion 63 in the thickness direction, but remains at either the front surface portion 61 or the back surface portion 62. It is preferably set in a range. Further, it is preferable that the compression portion is located only on the surface portion 61 from the viewpoint of not reducing the softness of the absorbent core 6. This compression portion can be formed linearly in the plane direction of the absorber 5 on the skin surface side with respect to the absorber 5 including, for example, the absorbent core 6 and the core wrap sheet 7. Examples of the linear compression portion include those arranged in an oblique grid pattern with respect to the longitudinal direction Y and the width direction X. The shape of the compression portion is not particularly limited as long as it exerts the above-mentioned action, and examples thereof include a staggered shape and a wavy shape in addition to the above-mentioned diagonal grid shape. Further, the compression portion is not limited to the case where it is provided only on the absorber 5, and for example, the absorber 5 and the surface sheet 3 may be integrally compressed.

Next, each component will be described.

(Absorbent 5)
As the liquid-retaining absorber 5, any one that is usually used for various absorbent articles such as diapers can be arbitrarily adopted as long as it exhibits the effect of the present invention.
The absorber 5 preferably contains synthetic fibers. Specific examples of synthetic fibers include polypropylene fibers, polyethylene fibers, and polyester fibers. Further, among the absorbent core 6 and the core wrap sheet 7 constituting the absorber 5, it is preferable that at least the absorbent core 6 contains synthetic fibers, and the synthetic fiber is synthesized in both the absorbent core 6 and the core wrap sheet 7. More preferably, it contains fibers. Since the absorber 5 contains synthetic fibers, it is less likely to settle even when exposed to excrement liquid. As a result, it is possible to prevent the discolored highly absorbent polymer 67 from being visually recognized from the gaps between the deformed absorbers 5.

In the absorbent core 6, it is preferable that the surface area of the highly absorbent polymer 67 increases toward the skin surface side. When the surface area of the highly absorbent polymer 67 is large, it tends to appear white due to diffused reflection of light. As a result, even if the highly absorbent polymer 67 near the skin surface side is discolored, the diaper 10 when viewed from the skin surface side can easily appear white.

In addition, the absorber 5 may have an antioxidant. Specific examples of antioxidants include triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] and 1,6-hexanediol-bis [3- (3,3). 5-Di-t-Butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydrotoxiphenyl propionate) and 3,5-di-t-butyl-4. Examples thereof include hindered phenolic antioxidants such as -hydroxybenzylphosphonate-diethyl ester, and amine-based antioxidants such as n-butylamine, triethylamine and diethylaminomethylmethacrylate. The antioxidant includes the absorber 5. It may be contained in any one of the constituent absorbent core 6 and the core wrap sheet 7, and may be contained in both. For example, it may be contained in the synthetic fiber in the absorber or hot. It may be contained in the melt adhesive, but does not include the inclusion of an antioxidant in the highly absorbent polymer, thereby eliminating the use of expensive highly absorbent polymers containing components that suppress discoloration. Even if a general-purpose highly absorbent polymer is used, the discoloration of the highly absorbent polymer is suppressed in combination with the action of the above-mentioned configuration of the absorbent core 6, and even if there is discoloration, it stands out from the outside of the diaper 10. Can be eliminated.

(Surface sheet 3)
The surface sheet 3 is liquid permeable, and those usually used for various absorbent articles such as diapers can be used without particular limitation. A hydrophilic thermal-bonded non-woven fabric is preferable, and an air-through non-woven fabric is particularly preferable, from the viewpoint of rapidly permeating the excreted body fluid and transferring it to the absorber and improving the touch. It is preferable that the thermoplastic resin fiber is hydrophilized and the fiber is three-dimensionally crimped such as a secondary crimp or a tertiary crimp. Specifically, polyethylene, polypropylene, polyester, nylon, and composite fibers thereof are prepared, cut to a predetermined length, and coated with various hydrophilic agents before forming staples. Examples of the hydrophilizing agent include various alkyl sulfonates typified by α-olefin sulfonate, acrylate, acrylate / acrylamide copolymer, ester amide, ester amide salt, polyethylene glycol and its derivatives, and water-soluble. A hydrophilization treatment with a hydrophilizing agent known to those skilled in the art can be used, such as a sex polyester resin, various silicone derivatives, various sugar derivatives, and a mixture thereof.

The surface sheet 3 preferably has an uneven structure. When the surface sheet 3 having an uneven structure is arranged on the skin surface side of the absorber, diffused reflection of light is likely to occur on the skin surface side of the surface sheet 3, and the diaper 10 is likely to appear white when viewed from the skin surface side. Become. As a result, the discolored highly absorbent polymer 67 becomes difficult to see from the outside.

It is preferable that the fibers constituting the surface sheet 3 contain a color tone changing agent. The color tone changing agent refers to a component having an action of lowering the transmittance of light incident on the surface sheet 3 and scattering it. By containing the color tone changing agent in the constituent fibers of the surface sheet 3, the discolored highly absorbent polymer 67 becomes difficult to see from the skin surface side.

Specific examples of the color tone changing agent include inorganic powders and organic powders having a refractive index different from that of the constituent fibers of the surface sheet 3.
Examples of the inorganic powder include titanium oxide, porous silicon oxide (silica), porous silica, aluminum oxide (alumina), lime, and clay minerals. Examples of clay minerals include smectite, montmorillonite, bentonite, kaolinite, sericite, illite, gloconite, chlorite, zeolite, talc, and mizukanite.
Examples of the organic powder include polyethylene powder, polyester powder, polypropylene powder, polyacrylic powder, polyacrylate powder, cellulose powder, viscose powder, silk powder, silicone compound powder, fluorine compound powder, and the like. In addition, these organic powders may be colored with a dye. Above all, it is preferable to use titanium oxide as the color tone changing material.
The content of the color tone changing agent is preferably 0.1% by mass or more, more preferably 1% by mass or more, still more preferably 3% by mass or more, assuming that the entire constituent fibers of the surface sheet 3 are 100% by mass. By containing titanium oxide in the constituent fibers of the surface sheet 3 in a certain amount or more, light can be effectively scattered. On the other hand, the upper limit of the content of titanium oxide in the constituent fibers of the surface sheet 3 is not particularly limited as long as it exhibits the effect of the present invention, but it is practically 10% by mass or less.

(Back sheet 4)
For the back sheet 4, a breathable film alone, a composite sheet in which a film and a non-woven fabric are bonded together, and a water-repellent non-woven fabric (SMS, SMMS, etc.) are used. It is preferable to use the moisture permeable film alone as a leak-proof material in terms of cost and matching with a slip-preventing adhesive. In this case, the film material is a film obtained by melting and kneading a thermoplastic resin and an inorganic filler incompatible with the thermoplastic resin and extruding the film to a predetermined size to form fine pores, or essentially water vapor. Examples thereof include a non-porous film having high compatibility with the film and capable of discharging water vapor like a permeable film.

It is preferable that the back surface sheet 4 is provided with the above-mentioned colored portion. It is preferable that the position of the colored portion overlaps with the position where a large amount of the highly absorbent polymer 67 exists in the absorbent core 6 in the plan view of the absorbent core 6. In particular, when a cute character such as a rabbit or a cat is printed on the back sheet 4 as the colored portion, the discoloration of the highly absorbent polymer 67 becomes less noticeable from the back sheet 4, and at the same time, the appeal of the consumer to the diaper 10 is increased, which is preferable.

(Intermediate sheet)
The absorbent body 1 constituting the diaper 10 preferably has an intermediate sheet (not shown) in addition to the front surface sheet 3, the back surface sheet 4 and the absorbent body 5. By covering the absorbent core 6 with an intermediate sheet other than the surface sheet 3 and the core wrap sheet 7, the discolored high-absorbent polymer 67 inside the absorbent core 6 can be further obscured.

Further, as the exterior body 2, the side sheet 9, the elastic member arranged therein, and the exterior non-woven fabric 48 constituting the diaper 10, various materials usually used in this kind of article can be adopted.

As described above, in the diaper 10 of the present embodiment, since the discoloration of the highly absorbent polymer 67 is difficult to see from the outside, a good appearance is maintained without using the highly absorbent polymer containing a component that suppresses the discoloration. it can.

Although the diaper 10 of the present embodiment is shown as a pants type diaper, the present invention is not limited to this, and a tape type diaper may be used. Further, in the diaper 10 of the present embodiment, the outer body is shown as being separated into the front side and the rear side, but the diaper 10 is not limited to this, and various shapes can be adopted. For example, the exterior body may have a shape that covers the entire front side portion 10F, middle portion 10C, and rear side portion 10R of the diaper 10, and may have a shape that is confined in the width direction in the middle portion 10C of the diaper 10. The shape of the absorbent core 6 is not limited to that of the present embodiment, and various shapes can be adopted. For example, the planar shape of the absorbent core 6 may be constricted in the width direction X in the intermediate portion C.

The absorbent article of the present invention is a concept including an absorbent article such as a panty liner, an incontinence pad, a sanitary napkin, and a urine absorbing pad, in addition to the diaper of the above embodiment. In addition, other members may be appropriately incorporated into the above configuration according to the intended use and function.

With respect to the embodiments described above, the present invention further discloses the following absorbent articles:

<1>
An absorbent article comprising an absorbent core having an absorbent core and a core wrap sheet covering the outer periphery of the absorbent core.
The absorbent core consists of an aggregate of a highly absorbent polymer and pulp fibers.
The absorbent core is divided into a front surface portion located on the skin surface side, a back surface portion located on the non-skin surface side, and a center portion in the thickness direction located between the front surface portion and the back surface portion in the thickness direction. Being done
An absorbent article in which the central portion in the thickness direction is a high-density layer of a highly absorbent polymer having a larger mass ratio of the highly absorbent polymer to the pulp fibers than the front surface portion and the back surface portion.

<2>
The absorbency according to <1>, wherein the mass ratio is 1.0 or more and 2.0 or less in the central portion in the thickness direction, and 0.25 or more and 0.75 or less in the front surface portion and the back surface portion. Goods.

<3>
The mass ratio is preferably 1.25 or more, more preferably 1.5 or more, more preferably 1.8 or less, and more preferably 1.6 or less in the central portion in the thickness direction, as described in <2>. Absorbent article.
<4>
The mass ratio of the front surface portion and the back surface portion is preferably 0.38 or more, more preferably 0.4 or more, more preferably 0.63 or less, and more preferably 0.5 or less. Or the absorbent article according to <3>.
<5>
The mass ratio of the highly absorbent polymer to the pulp fiber in the central portion in the thickness direction is 1.3 times or more and 8 times or less with respect to the mass ratio of the highly absorbent polymer to the pulp fiber in the front surface portion and the back surface portion. , 2.0 times or more, more preferably 3.0 times or more, preferably 5 times or less, more preferably 4 times or less, the absorbability according to any one of <2> to <4>. Goods.

<6>
The absorbent article according to any one of <1> to <5>, wherein a member having a colored portion is arranged on at least one of the skin surface side and the non-skin surface side of the absorbent core.

<7>
The absorbent article according to <6>, wherein the colored portion is colored in a region of 10% or more of the area of the member having the colored portion.
<8>
The absorbent article according to <6> or <7>, wherein the color of the colored portion is darker than the color of the discolored highly absorbent polymer.
<9>
The absorbent article according to any one of <6> to <8>, wherein the color of the colored portion is a complementary color of the color of the discolored highly absorbent polymer.
<10>
The absorbent article according to any one of <6> to <9>, wherein the color of the colored portion is green, blue or purple.

<11>
In the plan view of the absorbent core, a high basis weight region and a low basis weight area having a basis weight lower than the high basis weight area are arranged, and the plane area of the absorbent core is forward in the longitudinal direction. When divided into a portion, an intermediate portion including a liquid receiving region, and a rear portion, the high basis weight region includes at least the liquid receiving region of the intermediate portion, and the low basis weight region includes at least the rear portion. The absorbent article according to any one of <1> to <10>.

<12>
The basis weight of the high basis weight region is 120% or more and 250% or less, preferably 140% or more, and preferably 230% or less with respect to the basis weight of the low basis weight region. The absorbent article according to <11>.
<13>
The basis weight of the high basis weight region is 150 g / m ² or more and 900 g / m ² or less, preferably 200 g / m ² or more, more preferably 250 g / m ² or more, and 850 g / m. preferably ² or less, more preferably 800 g / ^{m 2} or less, the absorbent article according to <12>.
<14>
The basis weight of the low basis weight region is 100 g / m ² or more and 600 g / m ² or less, preferably 150 g / m ² or more, more preferably 200 g / m ² or more, and 550 g / m. preferably ² or less, more preferably 500 g / ^{m 2} or less, the absorbent article according to <12> or <13>.
<15>
In the longitudinal direction of the absorbent core 6, the length of the high basis weight region is 50% or more and 90% or less, preferably 60% or more, and preferably 70% or more of the total length of the absorbent core 6. The absorbent article according to any one of <11> to <14>, wherein the content is more preferably 85% or less, and more preferably 80% or less.
<16>
In the longitudinal direction of the absorbent core 6, the length of the low basis weight region is 10% or more and 50% or less, preferably 15% or more, and preferably 20% or more of the total length of the absorbent core 6. The absorbent article according to any one of <11> to <15>, wherein the content is more preferably 40% or less, and more preferably 30% or less.

<17>
The member having the colored portion according to any one of <6> to <10> is arranged on the non-skin surface side of the absorbent core.
The absorbent article according to any one of <11> to <16>, wherein the high basis weight region and the position of the colored portion overlap in a plan view of the absorbent core.

<18>
The absorbent article according to <17>, wherein the overlap between the position of the high basis weight region and the position of the colored portion occupies 10% or more of the area of the high basis weight region.

<19>
The absorbent article according to any one of <6> to <18>, wherein the position of the colored portion and the position of the end portion in the longitudinal direction of the absorbent core overlap in a plan view.

<20>
The absorbent article according to any one of <6> to <19>, wherein a slit portion is arranged in the absorbent core, and the position of the slit portion and the position of the colored portion overlap in a plan view.
<21>
The absorbent article according to <20>, wherein the core wrap sheets arranged on the skin surface side and the non-skin surface side of the absorbent core are adhered to each other at the slit portion.

<22>
The absorbent article according to <20> or <21>, wherein the width of the slit portion is 1 mm or more and 20 mm or less, preferably 3 mm or more, and preferably 15 mm or less.
<23>
The absorbent article according to any one of <20> to <22>, wherein the length of the slit portion is 50 mm or more and 350 mm or less, preferably 100 mm or more, and preferably 300 mm or less.
<24>
The separation distance between the rear end of the slit portion and the boundary position between the low basis weight region and the high basis weight region is 5 mm or more and 50 mm or less, more preferably 10 mm or more. The absorbent article according to any one of <20> to <23>, more preferably 45 mm or less.

<25>
The absorbent article according to any one of <1> to <24>, wherein the absorber has a compression portion.
<26>
The absorber has a portion in which the core wrap sheets are laminated with each other.
The absorbent article according to any one of <1> to <25>, wherein the position where a large amount of the highly absorbent polymer is present and the position of the portion where the core wrap sheet is laminated overlap in a plan view. ..

<27>
The absorbent article according to any one of <1> to <26>, wherein the absorber contains synthetic fibers.
<28>
The absorbent article according to any one of <1> to <27>, wherein the surface area of the highly absorbent polymer is larger toward the skin surface side in the absorbent core.
<29>
The absorbent article according to any one of <1> to <28>, wherein a surface sheet having an uneven structure is arranged on the skin surface side of the absorbent body.
<30>
The color tone changing agent is contained in an amount of 0.1% by mass or more, preferably 1% by mass or more, and preferably 3% by mass or more, assuming that the entire constituent fibers of the surface sheet are 100% by mass. The absorbent article according to <29>, which is more preferably contained and preferably contained in an amount of 10% by mass or less.
<31>
The absorbent article according to <29> or <30>, wherein an intermediate sheet is arranged between the absorber and the surface sheet.
<32>
The absorbent article according to any one of <1> to <31>, wherein the absorber has an antioxidant.

1 Absorbent body 11 Side seal 12 Waist opening 13 Leg opening 2 Exterior 21 Front exterior 22 Rear exterior 3 Front sheet 4 Back sheet 5 Absorber 6 Absorbent core 61 Front surface 62 Back surface 63 Thickness direction Central part (highly absorbent polymer high density layer)
67 Highly absorbent polymer 68 Pulp fiber 6H High basis weight area 6L Low basis weight area 6E Longitudinal end 7 Core wrap sheet 71 Skin side core wrap sheet 72 Non-skin side core wrap sheet 75 Laminated part of core wrap sheet 8 Slit part 9 Side sheet 91 Elastic member 92 Solid gather part 93 Elastic member 94 Leg gather part 10 Diaper 10F Front side of diaper 10C Middle part of diaper 10R Rear side of diaper 10D Girth part of diaper F Front side of absorbent core C Middle part of the absorbent core R Rear part of the absorbent core Y Longitudinal direction of the absorbent core (or longitudinal direction of the absorbent body)
X Width direction of the absorbent core (or width direction of the absorbent body)

(Method of measuring the mass ratio of the highly absorbent polymer 67 to the pulp fiber 68)
First, while observing the cross section of the measurement target portion of the absorbent core 6 with a microscope, the cross section is divided into three equal parts in the thickness direction, and each portion of the front surface portion 61, the central portion 63 in the thickness direction, and the back surface portion 62 is collected.
For each of the collected sites, each of the mixture of the superabsorbent polymer 67 and the pulp fiber 68 was quantified based on the method for quantifying the fiber and / or the water-absorbent polymer described in Japanese Patent No. 4225821, and the high absorption to the pulp fiber 68 was obtained. The mass ratio of the sex polymer 67 is calculated.
Specifically, after measuring the weight of each part taken, at each site, to reduce the molecular weight of the superabsorbent polymer 67. The molecular weight of the highly absorbent polymer 67 can be reduced by irradiation with ultraviolet rays. At that time, a mixture of the highly absorbent polymer 67 and the pulp fiber 68 of each of the collected parts is placed in a mesh bag or the like and immersed in an aqueous solution containing ascorbic acid and riboflavin. After the highly absorbent polymer is swollen by immersion, the mesh bag is taken out from the aqueous solution and irradiated with the above ultraviolet rays to reduce the molecular weight of the highly absorbent polymer 67. Next, the components produced by the reduction in molecular weight are removed by washing with water. After thoroughly washing the removed mesh bag with water, it is dehydrated and dried to measure the mass. The mass of the pulp fiber 68 is calculated by subtracting the mass of the mesh bag alone from the measured mass, and the mass of the pulp fiber 68 is subtracted from the mass of each part measured first to obtain the mass of the highly absorbent polymer 67. Based on these, the mass ratio of the highly absorbent polymer 68 to the pulp fiber 68 at each site is calculated. The average value of the mass ratio obtained by performing the above measurement three times is taken as the mass ratio at each part of the front surface portion 61, the central portion 63 in the thickness direction, and the back surface portion 62.

Examples of the member having a colored portion on the skin surface side of the absorbent core 6 include a core wrap sheet 7 and a surface sheet 3. Further, when there is an intermediate sheet (not shown) between the surface sheet 3 and the core wrap sheet 7, the intermediate sheet is also included in the member on the skin surface side of the absorbent core 6. Examples of the member having a colored portion on the non-skin surface side of the absorbent core 6 include a core wrap sheet 7, a back surface sheet 4, and an exterior nonwoven fabric 48. Further, with respect to the front exterior body 21 and the rear exterior body 22, the portion folded back toward the skin surface side of the absorbent body 1 becomes a member on the skin surface side of the absorbent core 6, and the non-skin surface side of the absorbent body 1 The portion arranged on the non-skin surface side of the absorbent core 6 is a member.

Specific examples of the color tone changing agent include inorganic powders and organic powders having a refractive index different from that of the constituent fibers of the surface sheet 3.
Examples of the inorganic powder include titanium oxide, porous silicon oxide (silica), porous silica, aluminum oxide (alumina), lime, and clay minerals. Examples of clay minerals include smectite, montmorillonite, bentonite, kaolinite, sericite, illite, gloconite, chlorite, zeolite, talc, and mizukanite.
Examples of the organic powder include polyethylene powder, polyester powder, polypropylene powder, polyacrylic powder, polyacrylate powder, cellulose powder, viscose powder, silk powder, silicone compound powder, fluorine compound powder, and the like. In addition, these organic powders may be colored with a dye. Above all, it is preferable to use titanium oxide as a color tone changing agent .
The content of the color tone changing agent is preferably 0.1% by mass or more, more preferably 1% by mass or more, still more preferably 3% by mass or more, assuming that the entire constituent fibers of the surface sheet 3 are 100% by mass. By containing titanium oxide in the constituent fibers of the surface sheet 3 in a certain amount or more, light can be effectively scattered. On the other hand, the upper limit of the content of titanium oxide in the constituent fibers of the surface sheet 3 is not particularly limited as long as it exhibits the effect of the present invention, but it is practically 10% by mass or less.

Claims (10)

An absorbent article comprising an absorbent core having an absorbent core and a core wrap sheet covering the outer periphery of the absorbent core.
The absorbent core consists of an aggregate of a highly absorbent polymer and pulp fibers.
The absorbent core is divided into a front surface portion located on the skin surface side, a back surface portion located on the non-skin surface side, and a center portion in the thickness direction located between the front surface portion and the back surface portion in the thickness direction. Being done
An absorbent article in which the central portion in the thickness direction is a high-density layer of a highly absorbent polymer having a larger mass ratio of the highly absorbent polymer to the pulp fibers than the front surface portion and the back surface portion. The absorbent article according to claim 1, wherein the mass ratio is 1.0 or more and 2.0 or less in the central portion in the thickness direction, and 0.25 or more and 0.75 or less in the front surface portion and the back surface portion. The absorbent article according to claim 1 or 2, wherein a member having a colored portion is arranged on at least one side of the absorbent core on the skin surface side and the non-skin surface side. In the plan view of the absorbent core, a high basis weight area and a low basis weight area having a lower basis weight than the high basis weight area are arranged.
When the plane region of the absorbent core is divided into a front portion, an intermediate portion including a liquid receiving region, and a rear portion in the longitudinal direction, the high basis weight region includes at least the liquid receiving region of the intermediate portion. The absorbent article according to any one of claims 1 to 3, wherein the low basis weight region includes at least the rear portion. The member having the colored portion according to claim 3 is arranged on the non-skin surface side of the absorbent core.
The absorbent article according to claim 4, wherein the high basis weight region and the position of the colored portion overlap in a plan view of the absorbent core. The absorbent article according to any one of claims 3 to 5, wherein the position of the colored portion and the position of the end portion in the longitudinal direction of the absorbent core overlap in a plan view. The absorbent article according to any one of claims 3 to 6, wherein a slit portion is arranged in the absorbent core, and the position of the slit portion and the position of the colored portion overlap in a plan view. The absorbent article according to claim 7, wherein the core wrap sheets arranged on the skin surface side and the non-skin surface side of the absorbent core are adhered to each other at the position of the slit portion. The absorbent article according to any one of claims 1 to 8, wherein the absorber has a compression portion. The absorber has a portion in which the core wrap sheets are laminated with each other.
The absorbent article according to any one of claims 1 to 9, wherein the position where a large amount of the highly absorbent polymer is present and the position of the portion where the core wrap sheet is laminated overlap in a plan view.

Images