Laminate

Abstract

The purpose of the present invention is to provide a laminate that is of use in an absorbent article that demonstrates excellent diagonal leakage prevention even after multiple exposures to liquid. A laminate that is shaped so as to have a long direction and includes a liquid-permeable first sheet, a liquid-absorbent intermediate sheet, and a water-absorbent resin layer. The intermediate sheet includes a region A and a region B that is shaped so as to have a long direction. Region A and region B satisfy: at least one of relationships (1) and (2); and relationship (3). (1) When the density of region B is 1, the relative density of region A is no more than 0.6. (2) Region A is a protruding part that protrudes toward the water-absorbent resin layer, region B is a recessed part, and the height of the protruding part is at least 0.25 mm. (3) Region B extends across the intermediate sheet between the long ends and on the inside of the short ends, and a straight line that connects the extension direction ends of region B is substantially parallel to the short direction of the intermediate sheet.

Description

[Technical Field]

[0001] This invention relates to a laminate. More specifically, this invention relates to a laminate with improved resistance to liquid leakage in the direction of inclination. [Background technology]

[0002] Absorbent articles such as disposable diapers, urine pads, and sanitary napkins are composed of a laminate that includes an absorbent layer that absorbs liquid, a liquid-permeable surface sheet placed on the side that comes into contact with the body, and a liquid-impermeable back sheet placed on the side opposite to the side that comes into contact with the body.

[0003] Absorbent materials are generally designed to have a larger surface area in contact with the body in order to absorb more liquid. However, the larger the surface area in contact with the body, the more the absorbent material conforms to the curves of the body during use, creating an inclined surface where bodily fluids flow more quickly, making leakage more likely.

[0004] Examples of improvements to prevent leakage include the technique disclosed in Patent Document 1, which involves providing a leak-proof wall to a bodily fluid absorbent article, and the technique disclosed in Patent Document 2, which involves providing a pocket space between the leak-proof sheet and the surface sheet in the rear portion of the bodily fluid absorbent article. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 8-182702 [Patent Document 2] Japanese Patent Publication No. 2004-337314 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In both the Patent Document 1 and Patent Document 2, only a physical barrier is provided at the location where leakage in the bodily fluid absorbent article is expected, but the fact that the liquid can easily flow to that location remains unchanged. Considering the actual usage conditions in which a single absorbent article may be exposed to liquid multiple times, such a physical barrier alone may not be sufficient to prevent leakage in situations where the liquid can still easily flow.

[0007] Therefore, the present invention aims to provide a laminate useful for absorbent articles that has excellent properties in reducing the risk of leakage in the inclined direction even after being exposed to liquid multiple times (hereinafter, the property of reducing the risk of leakage in the inclined direction will also be referred to as "inclined direction leakage prevention"). [Means for solving the problem]

[0008] The inventors conducted diligent research and discovered that by providing a liquid-absorbing sheet beneath the absorbent material in the laminate, and by configuring the liquid-absorbing sheet so that a region with a relatively lower density than other regions and / or a convex region towards the water-absorbing resin side is provided in a predetermined manner, it is possible to achieve excellent prevention of leakage in the inclined direction even after multiple exposures to liquid. The present invention was completed by further research based on this finding.

[0009] In other words, the present invention provides inventions in the following embodiments. Item 1. A laminate comprising a liquid-permeable first sheet, a liquid-absorbing intermediate sheet, and a second sheet, each having a longitudinal shape, and a water-absorbing resin layer interposed at least between the first sheet and the intermediate sheet, The intermediate sheet includes region A and region B having a longitudinal shape, A laminate in which region A and region B satisfy at least one of the following relationships (1) and (2), and also satisfy the following relationship (3): (1) Region A is low density and region B is high density, and the ratio of the density of region A to the density of region B (where the density of region B is 1) is 0.6 or less. (2) The region A is a convex portion that protrudes toward the side of the water-absorbing resin layer, and the region B is a concave portion, and the height of the convex portion is 0.25 mm or more. (3) The region B extends inside both short sides of the intermediate sheet and across between both long sides, and a straight line connecting one end and the other end in the extending direction of the region B is substantially parallel to the short side direction of the intermediate sheet. Item 2. The laminate according to Item 1, wherein the region A and the region B satisfy the relationship of the above (1) and (2). Item 3. The laminate according to Item 1 or 2, wherein the region A extends substantially parallel to the short side direction of the intermediate sheet. Item 4. The laminate according to Item 3, wherein the region B includes a strip portion arranged on the longitudinal center line of the intermediate sheet. Item 5. The laminate according to any one of Items 1 to 4, wherein a plurality of the region A and the region B are alternately arranged in the short side direction of those regions. Item 6. The laminate according to Item 5, including a strip portion in which a plurality of the region A and the region B are arranged in parallel. Item 7. The laminate according to any one of Items 1 to 6, wherein both ends in the extending direction of the region A are located inside the longitudinal ends of the intermediate sheet. Item 8. The laminate according to any one of Items 1 to 7, wherein the thickness of the region A of the intermediate sheet is 0.7 mm or more. Item 9. Further including another region B' extending in a direction including the longitudinal direction of the intermediate sheet, the other region B' being a high density and / or a concave portion, and when the density of the region B' is 1, the ratio of the density of the region A is 0.6 or less, and / or the height of the convex portion is 0.25 mm or more. The laminate according to any one of Items 1 to 9. Item 10. An absorbent article including the laminate according to any one of Items 1 to 9.

Advantages of the Invention

[0010] According to the present invention, there is provided a laminate useful for an absorbent article that exhibits excellent prevention against leakage in the inclined direction even when subjected to multiple liquid exposures.

Brief Description of the Drawings

[0011] [Figure 1] A schematic cross-sectional view of the first embodiment of the laminate of the present invention is shown. [Figure 2] Figure 1 schematically shows the external view of a portion of the intermediate sheet of the laminate (one of the shorter ends). [Figure 3] A schematic exploded view of the relevant portion of the laminate in Figure 1 is shown. [Figure 4] The laminate shown in Figure 1, after its initial exposure to liquid during use, is schematically represented in an exploded view, similar to Figure 3. [Figure 5] A schematic diagram of the external appearance of the intermediate sheet used in the second embodiment of the laminate of the present invention is shown. [Figure 6] An exploded view of the laminate of the second embodiment is shown in the same format as Figure 3. [Figure 7] The state in which the laminate 10a in Figure 6 is first exposed to liquid during use is schematically shown in an exploded view, similar to Figure 6. [Figure 8] A schematic diagram of the intermediate sheet used in the third embodiment of the laminate of the present invention is shown. [Figure 9] A schematic diagram of the intermediate sheet used in the fourth embodiment of the laminate of the present invention is shown. [Figure 10] A schematic diagram of the external appearance of a portion (including the longitudinal end) of the intermediate sheet used in the fifth embodiment of the laminate of the present invention is shown. [Figure 11] Several examples of the shapes of regions A and B are schematically shown. [Figure 12] Specific examples (examples) of the shapes of regions A and B are shown. [Figure 13] Specific examples (examples) of the shapes of regions A and B are shown. [Figure 14] Specific examples (comparative examples) of the shapes of regions A and B are shown. [Figure 15] Specific examples (comparative examples) of the shapes of regions A and B are shown. [Figure 16] A schematic diagram of the leak prevention test apparatus used in the example is shown. [Modes for carrying out the invention]

[0012] [1. Structure of the laminate] The present invention provides a laminate comprising a liquid-permeable first sheet, a liquid-absorbing intermediate sheet, and a second sheet, each having a longitudinal shape, and a water-absorbing resin layer interposed between at least the first sheet and the intermediate sheet; wherein the intermediate sheet includes region A and region B having a longitudinal shape; and region A and region B satisfy at least one of the following relationships (1) and (2), and also satisfy the following relationship (3): (1) region A is low density and region (1) B is of high density, and the ratio of the density of region A to the density of region B (where the density of region B is 1) is 0.6 or less; (2) region A is a convex portion that protrudes toward the water-absorbing resin layer, and region B is a concave portion, with a height of 0.25 mm or more; (3) region B extends inward from both short ends of the intermediate sheet, crossing between both long ends, and the straight line connecting one end of the extending direction of region B is substantially parallel to the short direction of the intermediate sheet. With such a structure, the laminate of the present invention can exhibit excellent prevention of leakage in the inclined direction even after being exposed to liquid multiple times. The laminate of the present invention will be described in detail below.

[0013] [1-1. First Embodiment] Figure 1 schematically shows a cross-sectional view of a first embodiment of the laminate of the present invention. Figure 1 shows a cross-sectional view when the laminate is cut by a plane perpendicular to its short side. Figure 2 schematically shows an external view of a part of the intermediate sheet (one short end portion) of the laminate of Figure 1. Figure 3 schematically shows an exploded view of the same part of the laminate of Figure 1. The laminate 10 shown in Figures 1 and 3 includes a permeable first sheet 20 having a longitudinal LD ​​shape, an absorbent intermediate sheet 30 as shown in Figure 2, and a second sheet 40, and a water-absorbent resin layer 51 interposed at least between the first sheet 20 and the intermediate sheet 30. Hereinafter, the lamination direction of the laminate 10 will also be referred to as "lamination direction LMD10". The laminate 10 also includes another absorbent resin layer 52 between the intermediate sheet 30 and the second sheet 40. Although not shown in the diagram, an adhesive layer may be interposed between the water-absorbing resin layer 51 and the intermediate sheet 30, and / or between the water-absorbing resin layer 52 and the second sheet 40.

[0014] In the laminate 10 of this embodiment, as shown in Figures 1 to 3, the intermediate sheet 30 has a low-density region as region A (hereinafter, low-density region A will also be referred to as "low-density region Al") and a high-density region as region B having a shape with a longitudinal direction LD-B (hereinafter, high-density region B will also be referred to as "high-density region Bh"). The high-density region Bh is located inside the short end SE of the intermediate sheet 30 and extends across the space between the two longitudinal ends LE of the intermediate sheet 30. Furthermore, the straight line L connecting one end of the extending direction of the high-density region Bh is approximately parallel to the short direction SD of the intermediate sheet 30.

[0015] The low-density region Al is configured such that the ratio of the density of the low-density region Al to the density of the high-density region Bh, when the density of the high-density region Bh is taken as 1, is 0.6 or less. From the perspective of further enhancing the leakage prevention property in the inclined direction against multiple liquid exposures, the ratio is preferably 0.5 or less, more preferably 0.45 or less, still more preferably 0.4 or less, even more preferably 0.3 or less, even more preferably 0.2 or less, and particularly preferably 0.12 or less. The lower limit of the ratio range is not particularly limited and may vary depending on the material and / or density-changing treatment of the intermediate sheet 30, etc. From the perspective of further enhancing the leakage prevention property in the inclined direction against multiple liquid exposures, for example, it is 0.05 or more, preferably 0.08 or more.

[0016] Specific examples of the density of the low-density region Al include, for example, 130 kg / m 3 as follows. From the perspective of further enhancing the absorption rate and / or the lateral leakage prevention property against multiple liquid exposures, the specific density of the low-density region Al is preferably 60 kg / m 3 or less, more preferably 50 kg / m 3 or less, more preferably 45 kg / m 3 or less, still more preferably 40 kg / m 3 or less, even more preferably 35 kg / m 3 or less, even more preferably 28 kg / m 3 or less, and particularly preferably 20 kg / m 3 as follows. The lower limit of the specific density range of the low-density region Al is not particularly limited as long as the water retention property can be ensured. For example, it is 16.5 kg / m 3 or more, preferably 18 kg / m 3 or more.

[0017] The method for creating different densities in the intermediate sheet 30 is not particularly limited. Since the intermediate sheet 30 is permeable, it has spaces or pores that communicate in the thickness direction, so any method for creating different densities that can physically reduce the volume occupied by these spaces or pores is acceptable. Specific methods include compressing the fabric of the intermediate sheet 30 in areas where high-density regions Bh should be provided, or manufacturing the fabric of the intermediate sheet 30 such that the weave is fine in areas where high-density regions Bh should be provided and coarse in areas where low-density regions Al should be provided.

[0018] The statement that the high-density region Bh is located inside the short edge SE of the intermediate sheet 30 means that there is no portion of the high-density region Bh that reaches the short edge SE of the intermediate sheet 30, and that the entire high-density region Bh is located inside the short edge SE of the intermediate sheet 30 in the in-plane direction. In other words, the portions of both short edges SE of the intermediate sheet 30 are composed of the low-density region Al. In the above description, the short edge SE refers to at least one of the two short edges of the intermediate sheet 30 that can be tilted downward in the vertical direction during use, and preferably refers to both short edges of the intermediate sheet 30.

[0019] The high-density region Bh extends across the two longitudinal ends LE of the intermediate sheet 30, and the straight line L connecting one end of the extension direction of the high-density region Bh to the other is approximately parallel to the short direction SD of the intermediate sheet 30. The fact that the straight line L is approximately parallel to the short direction SD means that the direction of the straight line L may be offset by ±5° from the short direction SD.

[0020] By providing the intermediate sheet 30 with high-density regions Bh in predetermined positions and shapes as described above, excellent leak prevention in the inclined direction against several liquid exposures is achieved. The mechanism by which such excellent leak prevention is obtained will be explained with reference to Figure 4. Figure 4 schematically shows the laminate 10 in the state after the first liquid exposure during use (hereinafter, the laminate 10 in this state will also be referred to as "laminated laminate 10'") in an exploded view, similar to Figure 3.

[0021] First, in the laminate 10, the intermediate sheet 30 has spaces or pores that communicate in the thickness direction and is in direct contact with the water-absorbing resin layer 51. Therefore, in the low-density region Al of the intermediate sheet 30, it is thought that some of the water-absorbing resin particles constituting the water-absorbing resin layer 51 are impregnated into the spaces or pores. In the high-density region Bh of the intermediate sheet 30, some of the water-absorbing resin particles constituting the water-absorbing resin layer 51 may also be impregnated, but due to the density difference between the two regions, it is thought that more water-absorbing resin particles are impregnated in the low-density region Al.

[0022] When the laminate 10 is exposed to liquid from the first sheet 20 side, the liquid moves in the lamination direction LMD 10 and reaches the intermediate sheet 30. As described above, the intermediate sheet 30 has a low-density region Al and a high-density region Bh, so more water diffuses in the low-density region Al. Consequently, more water-absorbing resin particles that were embedded in the low-density region Al absorb more water preferentially (i.e., earlier after the laminate 10 is exposed to liquid) and expand. In other words, water-absorbing resin particles that absorb water first and expand become localized in the low-density region Al. As a result, a difference in the expansion rate of water-absorbing resin particles is created throughout the water-absorbing resin layer 51, corresponding to the positions of the low-density region Al and the high-density region Bh of the intermediate sheet 30. Specifically, as schematically shown in Figure 4, in the water-absorbing resin layer 51, the portion 51A corresponding to the low-density region Al of the intermediate sheet 30 expands more than the portion 51B corresponding to the high-density region Bh (the water-absorbing resin layer 51 that first absorbed the exposed liquid will also be referred to as "water-absorbing resin layer 51'"). In other words, in the water-absorbing resin layer 51', there is a portion 51A that has expanded more in correspondence with the low-density region Al (hereinafter also referred to as "convex portion 51A"), and a portion 51B that has not expanded to the same size as the convex portion 51A and has become lower in correspondence with the high-density region Bh (hereinafter, the lower portion 51B will also be referred to as "recessed portion 51B"). Of these, since the recessed portion 51B has a shape with a longitudinal direction LD-B corresponding to the high-density region Bh, the side wall of the convex portion 51A adjacent to the recessed portion 51B has a shape that follows the longitudinal direction LD-B.

[0023] When the laminate 10' is subjected to further liquid exposure, some of the liquid that reaches the absorbent resin layer 51' flows through the recess 51B along the longitudinal direction of the sidewall of the protrusion 51A. In other words, after the liquid absorbed by the laminate 10' moves in the lamination direction LMD 10, when it is absorbed by the absorbent resin layer 51', it moves in a way that it spreads in the in-plane direction of the laminate 10' along the longitudinal direction LD-B of the sidewall of the protrusion 51A. If one of the two short ends SE of the laminate 10' is tilted downward in the vertical direction, the liquid will generally try to flow down toward that short end SE. However, the protrusion 51A acts as a physical barrier, making it difficult for the liquid to move in the in-plane direction perpendicular to the longitudinal direction LD-B of the sidewall of the protrusion 51A. Also, since the high-density region Bh is positioned inside the short end SE of the intermediate sheet 30, the recess 51B in the absorbent resin layer 51' can also be formed on the short end SE. Therefore, even for liquid that reaches the vicinity of the short end SE, the protrusion 51A of the short end SE acts as a physical barrier, blocking it. In this way, the risk of leakage from the short end SE (i.e., leakage in the direction of inclination) is also reduced.

[0024] In the above explanation, the "first liquid exposure" and the "next liquid exposure" may be continuous or intermittent.

[0025] [1-2. Second Embodiment] Figure 5 shows the intermediate sheet used in the second embodiment of the laminate of the present invention in the same format as in Figure 2. Figure 6 shows an exploded view of the laminate of the second embodiment in the same format as in Figure 3. The laminate 10a shown in Figure 6 is the same as the laminate 10 of the first embodiment described above, except that the intermediate sheet 30 has been changed to an intermediate sheet 30a.

[0026] The intermediate sheet 30a used in this embodiment has a region A which forms a convex portion that protrudes toward the water-absorbent resin layer (hereinafter, the region A which forms the convex portion will also be referred to as "convex region A+") and a region B which forms a recess (i.e., a recess relative to the convex region A+) with a shape having a longitudinal direction LD-B (hereinafter, the recessed region B will also be referred to as "recessed region B-"), and the recessed region B- is located inside the short end SE of the intermediate sheet 30a and extends across the space between the two longitudinal ends LE of the intermediate sheet 30a, and the straight line connecting one end of the extending direction of the high-density region Bh is substantially parallel to the short direction SD of the intermediate sheet 30a.

[0027] The convex region A+ is configured such that its height h (the height from the lowest part of the recessed region B- on the same plane as the convex region A+ to the highest part of the convex region) is 0.25 mm or more. From the viewpoint of further improving the ability to prevent leakage in the inclined direction against several liquid exposures, the height h is preferably 0.35 mm or more, more preferably 0.45 mm or more, even more preferably 0.6 mm or more, and even more preferably 0.7 mm or more. There is no particular upper limit to the height h range, but for example, it is 1 mm or less, preferably 0.9 mm or less.

[0028] In this embodiment, the intermediate sheet 30a has substantially the same density in the convex region A+ and the concave region B-.

[0029] The method for providing the convex region A+ and the concave region B- in the intermediate sheet 30a is not particularly limited. For example, the intermediate sheet 30a can be manufactured using a perforation technique with a substrate having concave and convex portions corresponding to the convex region A+ and the concave region B-, respectively, or the intermediate sheet 30a material can be prepared in block form and sliced ​​to reveal the uneven shape and cut into intermediate sheets 30a.

[0030] By providing the convex region A+ in a predetermined position and shape on the intermediate sheet 30a as described above, excellent leak prevention in the inclined direction against several liquid exposures is also achieved. The mechanism by which such excellent leak prevention is obtained will be explained with reference to Figure 7. Figure 7 schematically shows the laminate 10a in the state after the first liquid exposure during use (hereinafter, the laminate 10a in this state will also be referred to as "laminated laminate 10a'") in an exploded view, similar to Figure 6.

[0031] First, in the laminate 10a, the intermediate sheet 30a has spaces or holes that communicate in the thickness direction and is in direct contact with the water-absorbing resin layer 51. Therefore, the convex region A+ of the intermediate sheet 30a bites into the water-absorbing resin layer 51, and it is thought that some of the water-absorbing resin particles constituting the water-absorbing resin layer 51 are impregnated into the spaces or holes. Some of the water-absorbing resin particles constituting the water-absorbing resin layer 51 may also be impregnated in the concave region B- of the intermediate sheet 30a, but it is thought that the convex region A+ impregnates more water-absorbing resin particles due to the difference in height between the two regions.

[0032] When the laminate 10a is exposed to liquid from the first sheet 20 side, the liquid moves in the lamination direction LMD 10 and reaches the intermediate sheet 30a. As described above, the intermediate sheet 30a has a convex region A+ and a concave region B-, so the liquid comes into contact with the convex region A+ earlier and diffuses more quickly in the convex region A+. Consequently, more water-absorbing resin particles that were indented in the convex region A+ absorb more water more preferentially (i.e., earlier after the laminate 10a is exposed to liquid) and expand. In other words, water-absorbing resin particles that absorb water first and expand become localized in the convex region A+. As a result, a difference in the expansion rate of water-absorbing resin particles is created throughout the water-absorbing resin layer 51, corresponding to the positions of the convex region A+ and the concave region B- of the intermediate sheet 30a. Specifically, as schematically shown in Figure 7, in the water-absorbing resin layer 51', the portion 51A corresponding to the convex region A+ of the intermediate sheet 30a expands more than the portion 51B corresponding to the concave region B-. As a result, similar to Figure 4 of the first embodiment, a convex portion 51A is created that has side walls that cross both longitudinal ends LE and are along the longitudinal direction LD-B, and a concave portion 51B that does not expand to the same size as the convex portion 51A and is lower.

[0033] Therefore, when the laminate 10a' is subjected to further liquid exposure, similar to Figure 4 of the first embodiment, the liquid absorbed by the laminate 10' moves to spread in the in-plane direction of the laminate 10' along the longitudinal direction LD-B of the side wall of the protrusion 51A. Furthermore, even if the liquid attempts to flow down to one of the two short ends SE of the laminate 10a', which is tilted downward in the vertical direction, the protrusion 51A acts as a physical barrier, reducing the risk of leakage from the short end SE (i.e., leakage in the tilt direction).

[0034] In addition, in the above explanation, the "first liquid exposure" and the "next liquid exposure" may be continuous or intermittent.

[0035] [1-3. Third Implementation] Figure 8 shows the intermediate sheet 30b used in the third embodiment of the laminate of the present invention in the same format as in Figure 2. The laminate of the third embodiment is the same as the laminate 10 of the first embodiment described above, except that the intermediate sheet 30 is changed to the intermediate sheet 30b.

[0036] The intermediate sheet 30b used in this embodiment possesses both the characteristics of the intermediate sheet 30 used in the first embodiment and the characteristics of the intermediate sheet 30a used in the second embodiment (satisfying the relationships of (1) to (3) above). In other words, the intermediate sheet 30b has a region A which is low-density and forms a convex portion that is convex toward the water-absorbent resin layer (hereinafter, the low-density and convex region A will also be referred to as the "low-density / convex region Al+"), and a region B which is high-density and concave (i.e., a concave portion relative to the convex portion) (hereinafter, the high-density and non-convex region B will also be referred to as the "high-density / concave region Bh-"). The high-density / concave region Bh- is located inside the short end SE of the intermediate sheet 30b and extends across the space between the two long ends LE of the intermediate sheet 30b, and the straight line connecting one end of the extending direction of the high-density / concave region Bh- is substantially parallel to the short direction SD of the intermediate sheet 30b.

[0037] The ratio of the density of the low-density / convex region Al+ to the density of the high-density / concave region Bh- in the intermediate sheet 30b, when the density of the high-density region Bh- is set to 1, is the same as the ratio of the density of the low-density region Al to the density of the high-density region Bh in the intermediate sheet 30 used in the first embodiment. Furthermore, the height h of the low-density / convex region Al+ in the intermediate sheet 30b is the same as the height h of the convex region A+ in the intermediate sheet 30a used in the second embodiment.

[0038] Furthermore, the density of the low-density / protruding Al+ region in the intermediate sheet 30b is the same as the density of the low-density Al region in the intermediate sheet 30 used in the first embodiment.

[0039] The method for providing low-density, convex regions and high-density, concave regions in the intermediate sheet 30b is not particularly limited. Preferably, an embossing method is used, in which the fabric of the intermediate sheet 30b is compressed in the thickness direction from one side at the locations where high-density, concave regions should be provided.

[0040] The laminate of the third embodiment uses an intermediate sheet 30b that possesses the above-mentioned features. Therefore, when absorbing liquid, the absorbent resin layer adopts the characteristic expansion mode described in Figure 4 of the first embodiment and Figure 7 of the second embodiment, thereby reducing the risk of leakage in the inclined direction. Since the features of intermediate sheet 30 and intermediate sheet 30a each have the effect of reducing the risk of leakage in the inclined direction on their own, using an intermediate sheet 30b that combines these features can significantly improve the ability to prevent leakage in the inclined direction.

[0041] [1-4. Fourth Embodiment] Figure 9 shows the intermediate sheet 30c used in the fourth embodiment of the laminate of the present invention, in the same format as in Figure 2. The laminate of the third embodiment is the same as the laminate 10 of the first embodiment described above, except that the intermediate sheet 30 is changed to the intermediate sheet 30c.

[0042] Furthermore, the intermediate sheet 30c is reversible, having low-density / convex regions Al+ and high-density / recessed regions Bh- on both sides, similar to the intermediate sheet 30b used in the third embodiment. The high-density / recessed regions Bh- are located inside the short edge SE of the intermediate sheet 30c and extend across the space between the two long edges LE of the intermediate sheet 30c. The straight line connecting one end of the extending direction of the high-density / recessed regions Bh- is approximately parallel to the short direction SD of the intermediate sheet 30c.

[0043] The method for providing low-density, convex regions and high-density, concave regions on both sides of the intermediate sheet 30c is not particularly limited. Preferably, an embossing method is used, in which the fabric of the intermediate sheet 30c is compressed in the thickness direction from both sides at the locations where high-density, concave regions should be provided.

[0044] The laminate of the fourth embodiment uses an intermediate sheet 30b that, like the intermediate sheet 30b used in the third embodiment, combines the characteristics of the intermediate sheet 30 used in the first embodiment and the characteristics of the intermediate sheet 30a used in the second embodiment. Therefore, similar to the third embodiment, the ability to prevent leakage in the inclined direction can be significantly improved.

[0045] [1-5. Fifth Embodiment] In the laminate of the present invention, as long as region B is located inside the short edge of the intermediate sheet, it is not necessary whether region B reaches the long edge of the intermediate sheet. On the other hand, since the laminate of the present invention exhibits leak prevention by promoting the movement of absorbed liquid in an in-plane direction perpendicular to the inclination direction, that is, in a direction traversing between the two long edges, region B may be located inside the long edge LE of the intermediate sheet, in order to further reduce the risk of leakage from the long edge LE.

[0046] Figure 10 schematically shows the external view of a portion (including the longitudinal end) of the intermediate sheet used in the fifth embodiment of the laminate of the present invention. The laminate of the fifth embodiment is the same as the laminate 10 of the first embodiment described above, except that the intermediate sheet 30 is changed to an intermediate sheet 30d.

[0047] In this embodiment, the intermediate sheet 30d has a high-density region Bh located inside the longitudinal edge LE. The high-density region Bh being located inside the longitudinal edge LE means that there is no portion of the high-density region Bh that reaches the longitudinal edge LE of the intermediate sheet 30, and the entire high-density region Bh is positioned inward in the in-plane direction from both longitudinal edges LE of the intermediate sheet 30. In other words, the portions of both longitudinal edges LE of the intermediate sheet 30 are composed of a low-density region Al.

[0048] As a result, when the absorbent resin layer absorbs liquid, it expands to form a convex shape at the longitudinal end LE of the absorbent resin layer, just like at the short end SE, thereby forming a physical barrier and reducing the risk of leakage from the longitudinal end LE (i.e., lateral leakage).

[0049] In addition, the fifth embodiment was described using the case where region A is a low-density region Al similar to the first embodiment and region B is a high-density region Bh similar to the first embodiment. However, this fifth embodiment is also applicable when using an intermediate sheet in which the low-density region Al is changed to the convex region A+ in the second embodiment or the low-density / convex region Al+ in the third embodiment, and the high-density region Bh is changed to the concave region B- in the second embodiment or the high-density / concave region Bh- in the third embodiment. Furthermore, this fifth embodiment is also applicable when using an intermediate sheet with the cross-sectional shape described in the fourth embodiment.

[0050] [1-6. Modified versions of Area A and Area B] The shapes of regions A and B are not limited to those shown in the first embodiment described above. If region B is located inside the short end of the intermediate sheet, extends across the two long ends of the intermediate sheet, and the straight line connecting one end of region B in the direction of extension is substantially parallel to the short direction of the intermediate sheet, then, as explained with reference to Figure 4, the protrusions 51A formed by the absorption of the first exposed liquid act as a physical barrier, thereby exhibiting excellent leakage prevention in the inclined direction.

[0051] Figure 11 schematically illustrates several examples of the shapes of regions A and B. Figure 11 shows a plan view of the intermediate sheet as seen from the first sheet side, where the solid line represents region B and the blank areas other than the solid line represent region A. As described above, if region B exists in a predetermined position and manner, it exhibits excellent leak prevention in the inclined direction. Therefore, as shown in Figure 11(a), even if only one region B exists, the laminate of the present invention can exhibit excellent leak prevention in the inclined direction. Note that in all examples shown in Figure 11, region B is located inside the longitudinal edge LE, but it is also permissible for region B to reach the longitudinal edge LE.

[0052] From the viewpoint of improving the efficiency of guiding the absorbed liquid in the in-plane direction, it is preferable that either or both of regions A and B include a portion that forms a linear section. All examples shown in Figure 11 are examples in which regions A and B have portions that form a linear section.

[0053] If region B includes a linear portion, the shape of region B may be linear as shown in Figures 11(a) and 11(b), curved as shown in Figures 11(c) and 11(d), or broken as shown in Figure 11(e), similar to the embodiments described above. Even if the shape of region B is curved or broken, as shown in Figures 11(c) to 11(e), region B extends across the two longitudinal ends LE of the intermediate sheet, and the straight line L connecting one end of region B in the direction of extension is approximately parallel to the short direction SD of the intermediate sheet.

[0054] Among these, from the viewpoint of ensuring that the protrusion 51A described in Figure 4 evenly receives and blocks the liquid that is trying to flow in the direction of the incline, the shape of region B is preferably linear. In this case, as shown in Figures 11(a) and 11(b), region B extends approximately parallel to the short direction of the intermediate sheet. When region B extends approximately parallel to the short direction of the intermediate sheet, it means that the direction of extension of the linear region B may be shifted by about ±5° with respect to the short direction SD.

[0055] If region B includes a linear portion, it is preferable that the linear portion is positioned on the longitudinal centerline M of the intermediate sheet. If region B is composed of multiple linear portions, it is sufficient that at least one of the linear portions is positioned on the longitudinal centerline M of the intermediate sheet. Examples of such embodiments are shown in Figures 11(a) and 11(b). In such embodiments, when the absorbed liquid moves in the in-plane direction of the laminate, it can move to a location furthest from both short ends SE, which is preferable in that it provides better prevention of inclined leakage.

[0056] Regardless of their shapes, it is preferable that multiple alternating regions A and B are arranged in the short direction SD-B of those regions. Examples of such embodiments are shown in Figures 11(b), 11(c), 11(d), and 11(e). In this embodiment, when the liquid is absorbed, multiple groove-shaped recesses 42, as described in Figure 4, are formed, which is preferable because it can receive the liquid flowing in the inclined direction in multiple stages, further reducing the risk of leakage in the inclined direction.

[0057] Furthermore, it is even more preferable that both region A and region B include linear sections, and that multiple linear sections of region A and region B are arranged in parallel. Examples of such embodiments are shown in Figures 11(d), 11(e), and 11(f). Such embodiments are preferable because they can evenly receive liquid flowing in the direction of inclination over multiple stages, thereby further reducing the risk of leakage in the direction of inclination.

[0058] In addition, the intermediate sheet may further include other regions B' that extend in a direction including the longitudinal direction. In this case, region B' is the same as region B except that its direction of extension is different. Specifically, the other region B' is high density and / or recessed, the ratio of the density of region A to the density of region B' (where the density of region B' is 1) is 0.6 or less, and / or the height of the protrusions is 0.25 mm or more. When we say that the other region B' "extends in a direction including the longitudinal direction LD", we mean that the direction of extension of the other region B' includes the longitudinal direction LD component, regardless of whether it is parallel to the longitudinal direction LD or not. In other words, the "direction including the longitudinal direction LD" means any direction other than the direction perpendicular to the longitudinal direction LD (i.e., the short direction SD). Figure 11(f) is an example of an intermediate sheet further including other regions B' in this way. The example in Figure 11(f) is a form in which another region B' is added to the example in Figure 11(b), and regions B and B' form a grid.

[0059] The shapes of regions A and B shown in Figure 11 may be applied individually or as a combination of two or more shapes.

[0060] The width of region A (i.e., the width occupied by region A in the shorter direction) is not particularly limited, but for example, it can be 0.3 to 5 cm. From the viewpoint of further improving the ability to prevent leakage in the inclined direction against several liquid exposures, the width of region A is preferably 0.4 to 3.5 cm, more preferably 0.6 to 3 cm, even more preferably 0.8 to 2.8 cm, even more preferably 1 to 2.3 cm, and even more preferably 1.2 to 1.8 cm. The width of region A may be constant overall in its extending direction, or it may vary within the above range.

[0061] The width of region B (i.e., the width that region B occupies in the short direction SD-B) is not particularly limited, but from the viewpoint of further improving the ability to prevent leakage in the inclined direction against several liquid exposures, it is preferably 1 to 15 mm, more preferably 2 to 12 mm, even more preferably 3 to 10 mm, and most preferably 3 to 8 mm. The width of region B may be constant overall in its extending direction, or it may vary within the above range.

[0062] Furthermore, the modified example shown in Figure 11 can be applied to all of the embodiments described above.

[0063] [2. Materials and thickness of each component of the laminate] The material and thickness of each component constituting the laminate of the present invention are not particularly limited, and materials and thicknesses that allow each component to possess the above-described characteristics are appropriately selected. Unless otherwise specified, the following content can be applied to all of the above-described embodiments.

[0064] [2-1. Sheet 1] The first sheet is not particularly limited as long as it is permeable to liquid. The form of the first sheet is not particularly limited as long as it has spaces or holes that communicate in the thickness direction and the size of such spaces or holes is such that the water-absorbent resin constituting the water-absorbent resin layer does not pass through. Examples of the form of the first sheet include nonwoven fabric, woven fabric, and porous sheet. Among these forms, nonwoven fabric is preferred from the viewpoint of further improving the ability to prevent leakage in the inclined direction against several exposures of liquid.

[0065] The form of the nonwoven fabric is not particularly limited, and examples include air-through nonwoven fabrics, point-bonded nonwoven fabrics, spunbond nonwoven fabrics, spunlace nonwoven fabrics, thermal-bonded nonwoven fabrics, meltblown nonwoven fabrics, and airlaid nonwoven fabrics. Among these nonwoven fabrics, airlaid nonwoven fabrics are preferred from the viewpoint of further improving the ability to prevent leakage in the inclined direction against several exposures of liquid.

[0066] Examples of materials for the first sheet include polyolefins such as polyethylene (PE) and polypropylene (PP), polyesters such as polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), and polyethylene naphthalate (PEN), polyamides such as nylon, and resins such as rayon. These resins may be used individually or in combination of two or more types.

[0067] Furthermore, when the form of the first sheet is nonwoven or woven, the material of the first sheet may include, in addition to the resin fibers (synthetic resin fibers) mentioned above, natural fibers such as cotton, silk, hemp, and pulp (cellulose). These fibers may be used individually or in combination of two or more types.

[0068] Among the materials mentioned above, a combination of resin fibers and natural fibers is preferred, and a combination of polyolefin fibers and pulp is preferred, from the viewpoint of further improving the ability to prevent leakage in the inclined direction against repeated exposure to liquid.

[0069] While there are no particular limitations on the basis weight of the first sheet, it is preferably 20-60 g / m² from the viewpoint of further improving the ability to prevent leakage in the inclined direction against repeated liquid exposure. 2 Comfortably 30-50g / m 2 More preferably 35-45 g / m² 2 These are some examples.

[0070] The thickness of the first sheet is not particularly limited, but from the viewpoint of further improving the ability to prevent leakage in the inclined direction against several exposures of liquid, it is preferably 0.1 to 0.8 mm, more preferably 0.2 to 0.6 mm, even more preferably 0.3 to 0.5 mm, and most preferably 0.35 to 0.45 mm.

[0071] [2-2. Water-absorbing resin layer] The material for the water-absorbing resin layer (i.e., the water-absorbing resin) is not particularly limited as long as it is a resin that can absorb water and has the property of swelling when it absorbs water, that is, a resin commonly known as a superabsorbent polymer (SAP).

[0072] Specific examples of superabsorbent polymers include hydrolyzed starch-acrylonitrile graft copolymers, neutralized starch-acrylic acid graft polymers, saponified vinyl acetate-acrylic acid ester copolymers, crosslinked acrylic acid partially neutralized polymers, and partially neutralized polyacrylic acid. These superabsorbent polymers may be used individually or in combination of two or more types.

[0073] Among these water-absorbing resins, crosslinked acrylic acid partially neutralized polymers are preferred from the viewpoint of further improving the ability to prevent leakage in the inclined direction against several exposures of liquid. The degree of neutralization of the crosslinked acrylic acid partially neutralized polymer is, for example, 50 mol% or more, preferably 60 to 90 mol%, and more preferably 70 to 80 mol%. Methods for synthesizing crosslinked acrylic acid partially neutralized polymers are well known, and specifically include reverse-phase suspension polymerization and aqueous solution polymerization.

[0074] The thickness of the water-absorbing resin layer is not particularly limited, but for example, the thickness of the laminated surface of the laminate (i.e., the surface perpendicular to the lamination direction LMD10) is 1m. 2 For example, 25-600g / m 2 Preferably 50-450 g / m² 2 more comfortably 100-400g / m² 2 More preferably 150-200 g / m² 2 This thickness is one example.

[0075] The amount of saline solution absorbed by the superabsorbent resin is not particularly limited, but from the viewpoint of further improving the ability to prevent leakage in the inclined direction during several liquid exposures, it is preferably 30 to 75 g / g, more preferably 38 to 70 g / g, even more preferably 44 to 60 g / g, and even more preferably 50 to 55 g / g.

[0076] While there are no particular limitations on the amount of saline solution that the superabsorbent resin can hold, from the viewpoint of further improving its ability to prevent leakage in the inclined direction against several liquid exposures, it is preferably 20 to 60 g / g, more preferably 24 to 50 g / g, even more preferably 28 to 40 g / g, and even more preferably 30 to 35 g / g.

[0077] The absorption rate of physiological saline solution by the superabsorbent resin is not particularly limited, but from the viewpoint of further improving the ability to prevent leakage in the inclined direction during multiple liquid exposures, it is preferably 25 to 80 seconds, more preferably 28 to 60 seconds, even more preferably 32 to 58 seconds, even more preferably 36 to 48 seconds, and even more preferably 38 to 43 seconds.

[0078] While there are no particular limitations on the medium particle size of the water-absorbent resin, from the viewpoint of further improving the ability to prevent leakage in the inclined direction against several exposures of liquid, it is preferably 100 to 600 μm, more preferably 200 to 500 μm, even more preferably 300 to 400 μm, even more preferably 350 to 380 μm, and even more preferably 360 to 370 μm.

[0079] [2-3. Intermediate Sheet] The material of the intermediate sheet is not particularly limited as long as it is absorbent. The form of the intermediate sheet is not particularly limited as long as it has spaces, pores, and / or holes that communicate with at least the water-absorbent resin layer. Examples of intermediate sheets include nonwoven fabrics, woven fabrics, and porous sheets. Among these forms, nonwoven fabrics are preferred from the viewpoint of further improving the ability to prevent leakage in the inclined direction against several liquid exposures.

[0080] The form of the nonwoven fabric is not particularly limited, and examples include air-through nonwoven fabrics, point-bonded nonwoven fabrics, spunbond nonwoven fabrics, spunlace nonwoven fabrics, thermal-bonded nonwoven fabrics, meltblown nonwoven fabrics, and airlaid nonwoven fabrics. Among these nonwoven fabrics, air-through nonwoven fabrics are preferred from the viewpoint of further improving the ability to prevent leakage in the inclined direction against several exposures of liquid.

[0081] While there are no particular limitations on the basis weight of the intermediate sheet, from the viewpoint of further improving the ability to prevent leakage in the inclined direction against repeated liquid exposure, the lower limit is preferably 20 g / m². 2 Above, a comfortable 30g / m 2 More preferably 40 g / m² 2 More preferably 43 g / m² 2 The above is true, and the upper limit is preferably 60 g / m². 2 For a more efficient use, use 55g / m 2 More preferably 50 g / m 2 More preferably, 47 g / m 2 The following are listed:

[0082] The thickness t of the intermediate sheet is not particularly limited, but for example, it can be 0.7 mm or more. From the viewpoint of further improving the ability to prevent leakage in the inclined direction against several exposures of liquid, the thickness t is preferably 1.5 mm or more, more preferably 2 mm or more, and even more preferably 2.3 mm or more. There is no particular upper limit to the range of the thickness t of the intermediate sheet, but for example, it can be 4 mm or less, preferably 3 mm or less, and more preferably 2.8 mm or less. Note that in the case where region A is a convex part and region B is a concave part, as in the second to fourth embodiments, the thickness t of the intermediate sheet refers to the thickness of the part corresponding to region A.

[0083] [2-4. Other water-absorbing resin layers] The material for the other absorbent resin layer is not particularly limited, but can be selected from the absorbent resins listed above as materials for the absorbent resin layer. The absorbent resin used for the other absorbent resin layer may be the same as or different from the absorbent resin used for the absorbent resin layer above.

[0084] From the viewpoint of further improving the ability to prevent leakage in the inclined direction against multiple liquid exposures, preferred examples of the amount of saline solution absorbed by the superabsorbent resin used in other superabsorbent resin layers include 50-80 g / g, more preferably 55-76 g / g, even more preferably 60-73 g / g, and even more preferably 65-70 g / g.

[0085] From the viewpoint of further improving the ability to prevent leakage in the inclined direction against multiple liquid exposures, preferred examples of the saline water retention capacity of the superabsorbent resin used in other superabsorbent resin layers include 30-65 g / g, more preferably 35-60 g / g, even more preferably 40-50 g / g, and even more preferably 43-48 g / g.

[0086] From the viewpoint of further improving the ability to prevent leakage in the inclined direction against repeated liquid exposure, preferred examples of saline absorption rates of the superabsorbent resin used in other superabsorbent resin layers include 20 to 70 seconds, more preferably 25 to 60 seconds, even more preferably 32 to 58 seconds, even more preferably 36 to 48 seconds, and even more preferably 38 to 43 seconds.

[0087] The ratio of the amount of saline solution absorbed by the superabsorbent resin used in other superabsorbent resin layers, when the amount of saline solution absorbed by the superabsorbent resin used in one layer is taken as 1, is determined by the values ​​of the saline solution absorbed by each layer as described above. However, from the viewpoint of further improving the ability to prevent leakage in the inclined direction against several liquid exposures, the ratio is preferably 1 or more, more preferably 1.1 or more, even more preferably 1.18 or more, even more preferably 1.28 or more, and particularly preferably 1.32 or more. There is no particular upper limit to the ratio range, but for example, it is 2 or less, preferably 1.6 or less, more preferably 1.5 or less, and even more preferably 1.4 or less.

[0088] The ratio of the amount of saline solution that the absorbent resin used in other absorbent resin layers can hold, when the saline solution capacity of the absorbent resin used in one layer is set to 1, is determined by the values ​​of the saline solution capacity of each layer as described above. However, from the viewpoint of further improving the ability to prevent leakage in the inclined direction against several liquid exposures, the ratio is preferably 1 or more, more preferably 1.2 or more, even more preferably 1.3 or more, even more preferably 1.4 or more, and particularly preferably 1.45 or more. There is no particular upper limit to the ratio range, but for example, it is 2 or less, preferably 1.6 or less, and more preferably 1.5 or less.

[0089] The ratio of the saline solution absorption rate of the superabsorbent resin used in other superabsorbent resin layers to the saline solution absorption rate of the superabsorbent resin used in the superabsorbent resin layer, when the saline solution absorption rate of the superabsorbent resin used in the superabsorbent resin layer is set to 1, is determined by the values ​​of each saline solution absorption rate as described above. However, from the viewpoint of further improving the ability to prevent leakage in the inclined direction against several liquid exposures, the ratio is preferably 0.5 or higher, more preferably 0.6 or higher, even more preferably 0.7 or higher, even more preferably 0.8 or higher, even more preferably 0.9 or higher, and particularly preferably 0.95 or higher. There is no particular upper limit to the ratio range, but for example, it is 2 or less, preferably 1.5 or less, more preferably 1.2 or less, and even more preferably 1.1 or less.

[0090] The thickness of the other absorbent resin layers is not particularly limited, but can be selected from the values ​​listed above as the thickness of the absorbent resin layers. The thickness of the other absorbent resin layers and the thickness of the absorbent resin layer mentioned above may be the same or different.

[0091] [2-3. Sheet 2] Examples of the second sheet include permeable sheets and impermeable sheets. In the case of a permeable sheet, the second sheet may be selected from those used as the first sheet, or a sheet that has the same form and material as the first sheet except that it does not have the predetermined high-wettability and low-wettability regions of the first sheet.

[0092] If the second sheet is selected from those used as the first sheet, the first and second sheets may be the same or different.

[0093] [2-4.Adhesive layer] The adhesive resin composition used in the adhesive layer is not limited as long as it can bond the water-absorbing resin to the intermediate sheet and / or the second sheet, and can be appropriately selected by those skilled in the art. Since the laminate of the present invention is used to absorb water-based liquids, a preferred adhesive composition is a hot-melt adhesive composition that is stable to water-based solvents.

[0094] [3. Fabrication of the laminate] The method for producing the laminate of the present invention is not particularly limited, but it can be manufactured by, for example, the following method.

[0095] For example, a laminated material can be created by laminating a water-absorbent resin layer and a first sheet on a surface where regions A and B of the intermediate sheet are provided. Furthermore, another water-absorbent resin layer and a second sheet can be laminated on the intermediate sheet side of the laminated material, and the entire layer can be integrated to create a laminate.

[0096] Furthermore, in cases where an adhesive layer is interposed between the water-absorbent resin layer and the intermediate sheet, and between the water-absorbent resin layer and the second sheet, a laminated material can be created by laminating the adhesive layer, the water-absorbent resin layer, and the first sheet in that order on the surface where regions A and B of the intermediate sheet are provided. Then, another water-absorbent resin layer is laminated on the intermediate sheet side of the laminated material, and a second sheet with an adhesive layer laminated on its surface is laminated so that the adhesive layer faces the other water-absorbent resin layer, and all layers are integrated to create a laminate.

[0097] The first and second sheets can be the same shape and size, while the intermediate sheet can be slightly smaller than the first and second sheets. In this case, after all the layers have been laminated, the entire structure can be integrated by joining the edges of the first and second sheets together (for example, by heat bonding).

[0098] [4. Applications of laminates] The laminate of the present invention described above functions as an absorbent that exhibits excellent leak prevention in the inclined direction against several liquid exposures. Therefore, since the laminate of the present invention is useful for absorbent articles, the present invention also provides an absorbent article containing said laminate.

[0099] Absorbent articles are not particularly limited, but preferably those that need to absorb liquid multiple times and can be used in an inclined position. The liquid can be any liquid containing water. More specific examples of absorbent articles include disposable diapers, urine pads, sanitary napkins, pet sheets, food drip sheets, and waterproofing materials for power cables. [Examples]

[0100] The present invention will be described in detail below with reference to examples and comparative examples. However, the present invention is not limited to these examples.

[0101] (1) Synthesis of superabsorbent polymer particles (superabsorbent polymer; SAP) (1-1) Manufacturing Example 1: Synthesis of SAPa <First stage polymerization reaction> A reflux condenser, a dropping funnel, a nitrogen gas inlet tube, and a round-bottom cylindrical separable flask with an inner diameter of 11 cm and a capacity of 2 L were prepared. The flask was equipped with a stirring blade consisting of two stages of four inclined paddle blades with a blade diameter of 5 cm. 293 g of n-heptane was added to the flask as a hydrocarbon dispersion medium, and 0.736 g of maleic anhydride-modified ethylene-propylene copolymer (Mitsui Chemicals, Inc., High Wax 1105A) was added as a polymeric dispersant. The mixture was heated to 80°C while stirring to dissolve the dispersant, and then cooled to 50°C.

[0102] In a 300 mL beaker, 92.0 g (1.03 mol) of an 80.5% by mass acrylic acid aqueous solution was taken as a water-soluble ethylenically unsaturated monomer. While cooling from the outside, 147.7 g of a 20.9% by mass sodium hydroxide aqueous solution was added dropwise to neutralize to 75 mol%, and then 0.092 g of hydroxyethylcellulose (Sumitomo Seika Co., Ltd., HECAW-15F) as a thickening agent, 0.092 g (0.339 mmol) of 2,2'-azobis(2-amidinopropane) dihydrochloride as a water-soluble radical polymerization initiator, 0.018 g (0.067 mmol) of potassium persulfate, and 0.0046 g (0.026 mmol) of ethylene glycol diglycidyl ether as an internal crosslinking agent were added and dissolved to prepare the first stage monomer aqueous solution.

[0103] Then, the first monomer aqueous solution prepared above was added to a separable flask and stirred for 10 minutes. A surfactant solution prepared by heating and dissolving 0.736 g of sucrose stearate ester (Mitsubishi Chemical Foods Corporation, Ryoto Sugar Ester S-370) of HLB3 as a surfactant in 6.62 g of n-heptane was added, and the system was thoroughly purged with nitrogen while stirring at a stirrer speed of 500 rpm. The flask was then immersed in a 70°C water bath to raise the temperature and polymerization was carried out for 60 minutes to obtain the first stage polymerization slurry.

[0104] <Second stage polymerization reaction> In a 500 mL beaker, 128.8 g (1.44 mol) of an 80.5% by mass acrylic acid aqueous solution was placed as a water-soluble ethylenically unsaturated monomer. While cooling from the outside, 159.0 g of a 27% by mass sodium hydroxide aqueous solution was added dropwise to neutralize to 75 mol%, and then 0.129 g (0.476 mmol) of 2,2'-azobis(2-amidinopropane) 2-hydrochloride and 0.026 g (0.096 mmol) of potassium persulfate were added as water-soluble radical polymerization initiators, and 0.0116 g (0.067 mmol) of ethylene glycol diglycidyl ether was added as an internal crosslinking agent and dissolved to prepare the second stage monomer aqueous solution.

[0105] While stirring at a stirrer speed of 1000 rpm, the contents of the separable flask system were cooled to 25°C. Then, the entire amount of the second-stage monomer aqueous solution was added to the first-stage polymerization slurry, the system was purged with nitrogen for 30 minutes, and the flask was again immersed in a 70°C water bath to raise the temperature and carry out the polymerization reaction for 60 minutes to obtain a hydrated gel-like polymer.

[0106] After polymerization, 0.589 g of a 45% by mass aqueous solution of sodium pentasodium diethylenetriaminepentaacetate was added to the resulting hydrated gel polymer under stirring. The flask was then immersed in an oil bath set at 125°C, and 201.4 g of water was removed from the system by azeotropic distillation of n-heptane and water while refluxing the n-heptane. Subsequently, 4.42 g (0.507 mmol) of a 2% by mass aqueous solution of ethylene glycol diglycidyl ether was added to the flask as a surface crosslinking agent, and the mixture was held at 83°C for 2 hours.

[0107] Subsequently, the polymer particles were dried by heating and evaporating n-heptane and water in an oil bath at 125°C. These polymer particles were passed through a sieve with a mesh size of 850 μm, and 0.2% by mass of amorphous silica (Oriental Silicas Corporation, Toxil NP-S) relative to the mass of the polymer particles was mixed with the polymer particles to obtain 231.2 g of SAPa containing amorphous silica.

[0108] (1-2) Manufacturing Example 2: Synthesis of SAPb <First stage polymerization reaction> A reflux condenser, a dropping funnel, a nitrogen gas inlet tube, and a round-bottom cylindrical separable flask with an inner diameter of 11 cm and a capacity of 2 L were prepared. The flask was equipped with a stirring blade consisting of two stages of four inclined paddle blades with a blade diameter of 5 cm. 293 g of n-heptane was added to the flask as a hydrocarbon dispersion medium, and 0.736 g of maleic anhydride-modified ethylene-propylene copolymer (Mitsui Chemicals, Inc., High Wax 1105A) was added as a polymeric dispersant. The mixture was heated to 80°C while stirring to dissolve the dispersant, and then cooled to 50°C.

[0109] In a 300 mL beaker, 92.0 g (1.03 mol) of an 80.5% by mass acrylic acid aqueous solution was taken as a water-soluble ethylenically unsaturated monomer. While cooling from the outside, 147.7 g of a 20.9% by mass sodium hydroxide aqueous solution was added dropwise to neutralize to 75 mol%, and then 0.092 g of hydroxyethylcellulose (Sumitomo Seika Co., Ltd., HECAW-15F) as a thickening agent, 0.092 g (0.339 mmol) of 2,2'-azobis(2-amidinopropane) dihydrochloride as a water-soluble radical polymerization initiator, 0.018 g (0.067 mmol) of potassium persulfate, and 0.0046 g (0.026 mmol) of ethylene glycol diglycidyl ether as an internal crosslinking agent were added and dissolved to prepare the first stage monomer aqueous solution.

[0110] Then, the first monomer aqueous solution prepared above was added to a separable flask and stirred for 10 minutes. A surfactant solution prepared by heating and dissolving 0.736 g of sucrose stearate ester (Mitsubishi Chemical Foods Corporation, Ryoto Sugar Ester S-370) of HLB3 as a surfactant in 6.62 g of n-heptane was added, and the system was thoroughly purged with nitrogen while stirring at a stirrer speed of 500 rpm. The flask was then immersed in a 70°C water bath to raise the temperature and polymerization was carried out for 60 minutes to obtain the first stage polymerization slurry.

[0111] <Second stage polymerization reaction> In a 500 mL beaker, 128.8 g (1.44 mol) of an 80.5% by mass acrylic acid aqueous solution was placed as a water-soluble ethylenically unsaturated monomer. While cooling from the outside, 159.0 g of a 27% by mass sodium hydroxide aqueous solution was added dropwise to neutralize to 75 mol%, and then 0.129 g (0.476 mmol) of 2,2'-azobis(2-amidinopropane) 2-hydrochloride and 0.026 g (0.096 mmol) of potassium persulfate were added as water-soluble radical polymerization initiators, and 0.0116 g (0.067 mmol) of ethylene glycol diglycidyl ether was added as an internal crosslinking agent and dissolved to prepare the second stage monomer aqueous solution.

[0112] While stirring at a stirrer speed of 1000 rpm, the contents of the separable flask system were cooled to 25°C. Then, the entire amount of the second-stage monomer aqueous solution was added to the first-stage polymerization slurry, the system was purged with nitrogen for 30 minutes, and the flask was again immersed in a 70°C water bath to raise the temperature and carry out the polymerization reaction for 60 minutes to obtain a hydrated gel-like polymer.

[0113] After polymerization, 0.589 g of a 45% by mass aqueous solution of sodium pentasodium diethylenetriaminepentaacetate was added to the resulting hydrated gel polymer under stirring. The flask was then immersed in an oil bath set at 125°C, and 217.8 g of water was removed from the system by azeotropic distillation of n-heptane and water while refluxing the n-heptane. Subsequently, 4.42 g (0.507 mmol) of a 2% by mass aqueous solution of ethylene glycol diglycidyl ether was added to the flask as a surface crosslinking agent, and the mixture was held at 83°C for 2 hours.

[0114] Subsequently, the polymer particles were dried by heating and evaporating n-heptane and water in an oil bath at 125°C. These polymer particles were passed through a sieve with a mesh size of 850 μm, and 0.2% by mass of amorphous silica (Oriental Silicas Corporation, Toxil NP-S) relative to the mass of the polymer particles was mixed with the polymer particles to obtain 231.2 g of SAPb containing amorphous silica. The median particle size of SAPb was 355 μm.

[0115] (1-3) Manufacturing Example 3: Synthesis of SAPc <First stage polymerization reaction> A reflux condenser, a dropping funnel, a nitrogen gas inlet tube, and a round-bottom cylindrical separable flask with an inner diameter of 11 cm and a capacity of 2 L were prepared. The flask was equipped with a stirring blade consisting of two stages of four inclined paddle blades with a blade diameter of 5 cm. 293 g of n-heptane was added to the flask as a hydrocarbon dispersion medium, and 0.736 g of maleic anhydride-modified ethylene-propylene copolymer (Mitsui Chemicals, Inc., High Wax 1105A) was added as a polymeric dispersant. The mixture was heated to 80°C while stirring to dissolve the dispersant, and then cooled to 50°C.

[0116] In a 300 mL beaker, 92.0 g (1.03 mol) of an 80.5% by mass acrylic acid aqueous solution was placed, and while cooling from the outside, 147.7 g of a 20.9% by mass sodium hydroxide aqueous solution was added dropwise to neutralize to 75 mol%, and then 0.092 g of hydroxyethylcellulose (Sumitomo Seika Co., Ltd., HECAW-15F) as a thickening agent, 0.0736 g (0.272 mmol) of potassium persulfate as a water-soluble radical polymerization initiator, and 0.010 g (0.057 mmol) of ethylene glycol diglycidyl ether as an internal crosslinking agent were added and dissolved to prepare the first stage monomer aqueous solution.

[0117] Then, the first monomer aqueous solution prepared above was added to a separable flask and stirred for 10 minutes. After that, a surfactant solution was added, which was obtained by heating and dissolving 0.736 g of sucrose stearate ester (Mitsubishi Chemical Foods Corporation, Ryoto Sugar Ester S-370) of HLB3 as a surfactant in 6.62 g of n-heptane. The system was then thoroughly purged with nitrogen while stirring at a stirrer speed of 550 rpm, and the flask was immersed in a 70°C water bath to raise the temperature and carry out polymerization for 60 minutes to obtain the first stage polymerization slurry.

[0118] <Second stage polymerization reaction> In a 500 mL beaker, 128.8 g (1.44 mol) of an 80.5% by mass acrylic acid aqueous solution was placed, and while cooling from the outside, 159.0 g of a 27% by mass sodium hydroxide aqueous solution was added dropwise to neutralize to 75 mol%. Then, 0.103 g (0.381 mmol) of potassium persulfate was added as a water-soluble radical polymerization initiator, and 0.0116 g (0.067 mmol) of ethylene glycol diglycidyl ether was added as an internal crosslinking agent and dissolved to prepare the second stage monomer aqueous solution.

[0119] While stirring at a stirrer speed of 1000 rpm, the contents of the separable flask system were cooled to 25°C. Then, the entire amount of the second-stage monomer aqueous solution was added to the first-stage polymerization slurry, the system was purged with nitrogen for 30 minutes, and the flask was again immersed in a 70°C water bath to raise the temperature and carry out the polymerization reaction for 60 minutes to obtain a hydrated gel-like polymer.

[0120] After polymerization, 0.589 g of a 45% by mass aqueous solution of sodium pentasodium diethylenetriaminepentaacetate was added to the resulting hydrated gel polymer under stirring. The flask was then immersed in an oil bath set at 125°C, and 237.7 g of water was removed from the system by azeotropic distillation of n-heptane and water while refluxing the n-heptane. Subsequently, 4.42 g (0.507 mmol) of a 2% by mass aqueous solution of ethylene glycol diglycidyl ether was added to the flask as a surface crosslinking agent, and the mixture was held at 83°C for 2 hours.

[0121] Subsequently, the polymer particles were dried by heating and evaporating n-heptane and water in an oil bath at 125°C. These polymer particles were passed through a sieve with a mesh size of 850 μm, and 0.5% by mass of amorphous silica (Oriental Silicas Corporation, Toxil NP-S) relative to the mass of the polymer particles was mixed with the polymer particles to obtain 226.0 g of SAPc containing amorphous silica.

[0122] (1-4) Manufacturing Example 4: Synthesis of SAPd <First stage polymerization reaction> A reflux condenser, a dropping funnel, a nitrogen gas inlet tube, and a round-bottom cylindrical separable flask with an inner diameter of 11 cm and a capacity of 2 L were prepared. The flask was equipped with a stirring blade consisting of two stages of four inclined paddle blades with a blade diameter of 5 cm. 293 g of n-heptane was added to the flask as a hydrocarbon dispersion medium, and 0.736 g of maleic anhydride-modified ethylene-propylene copolymer (Mitsui Chemicals, Inc., High Wax 1105A) was added as a polymeric dispersant. The mixture was heated to 80°C while stirring to dissolve the dispersant, and then cooled to 50°C.

[0123] In a 300 mL beaker, 92.0 g (1.03 mol) of an 80.5% by mass acrylic acid aqueous solution was placed, and while cooling from the outside, 147.7 g of a 20.9% by mass sodium hydroxide aqueous solution was added dropwise to neutralize to 75 mol%, and then 0.092 g of hydroxyethylcellulose (Sumitomo Seika Co., Ltd., HECAW-15F) as a thickening agent, 0.0736 g (0.272 mmol) of potassium persulfate as a water-soluble radical polymerization initiator, and 0.010 g (0.057 mmol) of ethylene glycol diglycidyl ether as an internal crosslinking agent were added and dissolved to prepare the first stage monomer aqueous solution.

[0124] Then, the first monomer aqueous solution prepared above was added to a separable flask and stirred for 10 minutes. After that, a surfactant solution was added, which was obtained by heating and dissolving 0.736 g of sucrose stearate ester (Mitsubishi Chemical Foods Corporation, Ryoto Sugar Ester S-370) of HLB3 as a surfactant in 6.62 g of n-heptane. The system was then thoroughly purged with nitrogen while stirring at a stirrer speed of 550 rpm, and the flask was immersed in a 70°C water bath to raise the temperature and carry out polymerization for 60 minutes to obtain the first stage polymerization slurry.

[0125] <Second stage polymerization reaction> In a 500 mL beaker, 128.8 g (1.44 mol) of an 80.5% by mass acrylic acid aqueous solution was placed, and while cooling from the outside, 159.0 g of a 27% by mass sodium hydroxide aqueous solution was added dropwise to neutralize to 75 mol%. Then, 0.103 g (0.381 mmol) of potassium persulfate was added as a water-soluble radical polymerization initiator, and 0.0116 g (0.067 mmol) of ethylene glycol diglycidyl ether was added as an internal crosslinking agent and dissolved to prepare the second stage monomer aqueous solution.

[0126] While stirring at a stirrer speed of 1000 rpm, the contents of the separable flask system were cooled to 25°C. Then, the entire amount of the second-stage monomer aqueous solution was added to the first-stage polymerization slurry, the system was purged with nitrogen for 30 minutes, and the flask was again immersed in a 70°C water bath to raise the temperature and carry out the polymerization reaction for 60 minutes to obtain a hydrated gel-like polymer.

[0127] After polymerization, 0.589 g of a 45% by mass aqueous solution of sodium pentasodium diethylenetriaminepentaacetate was added to the resulting hydrated gel polymer under stirring. The flask was then immersed in an oil bath set at 125°C, and 257.7 g of water was removed from the system by azeotropic distillation of n-heptane and water while refluxing the n-heptane. Subsequently, 4.42 g (0.507 mmol) of a 2% by mass aqueous solution of ethylene glycol diglycidyl ether was added to the flask as a surface crosslinking agent, and the mixture was held at 83°C for 2 hours.

[0128] Subsequently, the polymer particles were dried by heating and evaporating n-heptane and water in an oil bath at 125°C. These polymer particles were passed through a sieve with a mesh size of 850 μm, and 0.5% by mass of amorphous silica (Oriental Silicas Corporation, Toxil NP-S) relative to the mass of the polymer particles was mixed with the polymer particles to obtain 228.0 g of SAPd containing amorphous silica. The median particle size of SAPd was 372 μm.

[0129] (1-5) Manufacturing Example 5: Synthesis of SAPe <First stage polymerization reaction> A reflux condenser, a dropping funnel, a nitrogen gas inlet tube, and a round-bottom cylindrical separable flask with an inner diameter of 11 cm and a capacity of 2 L were prepared. The flask was equipped with a stirring blade consisting of two stages of four inclined paddle blades with a blade diameter of 5 cm. 293 g of n-heptane was added to the flask as a hydrocarbon dispersion medium, and 0.736 g of maleic anhydride-modified ethylene-propylene copolymer (Mitsui Chemicals, Inc., High Wax 1105A) was added as a polymeric dispersant. The mixture was heated to 80°C while stirring to dissolve the dispersant, and then cooled to 50°C.

[0130] In a 300 mL beaker, 92.0 g (1.03 mol) of an 80.5% by mass acrylic acid aqueous solution was placed, and while cooling from the outside, 147.7 g of a 20.9% by mass sodium hydroxide aqueous solution was added dropwise to neutralize to 75 mol%, and then 0.092 g of hydroxyethylcellulose (Sumitomo Seika Co., Ltd., HECAW-15F) as a thickening agent, 0.0736 g (0.272 mmol) of potassium persulfate as a water-soluble radical polymerization initiator, and 0.010 g (0.057 mmol) of ethylene glycol diglycidyl ether as an internal crosslinking agent were added and dissolved to prepare the first stage monomer aqueous solution.

[0131] Then, the first monomer aqueous solution prepared above was added to a separable flask and stirred for 10 minutes. After that, a surfactant solution was added, which was obtained by heating and dissolving 0.736 g of sucrose stearate ester (Mitsubishi Chemical Foods Corporation, Ryoto Sugar Ester S-370) of HLB3 as a surfactant in 6.62 g of n-heptane. The system was then thoroughly purged with nitrogen while stirring at a stirrer speed of 550 rpm, and the flask was immersed in a 70°C water bath to raise the temperature and carry out polymerization for 60 minutes to obtain the first stage polymerization slurry.

[0132] <Second stage polymerization reaction> In a 500 mL beaker, 128.8 g (1.44 mol) of an 80.5% by mass acrylic acid aqueous solution was placed, and while cooling from the outside, 159.0 g of a 27% by mass sodium hydroxide aqueous solution was added dropwise to neutralize to 75 mol%, and then 0.090 g (0.333 mmol) of potassium persulfate as a water-soluble radical polymerization initiator and 0.0116 g (0.067 mmol) of ethylene glycol diglycidyl ether as an internal crosslinking agent were added and dissolved to prepare the second stage monomer aqueous solution.

[0133] While stirring at a stirrer speed of 1000 rpm, the contents of the separable flask system were cooled to 25°C. Then, the entire amount of the second-stage monomer aqueous solution was added to the first-stage polymerization slurry, the system was purged with nitrogen for 30 minutes, and the flask was again immersed in a 70°C water bath to raise the temperature and carry out the polymerization reaction for 60 minutes to obtain a hydrated gel-like polymer.

[0134] After polymerization, 0.265 g of a 45% by mass aqueous solution of sodium pentasodium diethylenetriaminepentaacetate was added to the resulting hydrated gel polymer under stirring. The flask was then immersed in an oil bath set at 125°C, and 271.4 g of water was removed from the system by azeotropic distillation of n-heptane and water while refluxing the n-heptane. Subsequently, 6.40 g (0.735 mmol) of a 2% by mass aqueous solution of ethylene glycol diglycidyl ether was added to the flask as a surface crosslinking agent, and the mixture was held at 83°C for 2 hours.

[0135] Subsequently, the polymer particles were dried by heating and evaporating n-heptane and water in an oil bath at 125°C. These polymer particles were passed through a sieve with a mesh size of 850 μm, and 0.5% by mass of amorphous silica (Oriental Silicas Corporation, Toxil NP-S) relative to the mass of the polymer particles was mixed with the polymer particles to obtain 230.6 g of SAPe containing amorphous silica. The median particle size of SAPe was 369 μm.

[0136] (2) Measurement of water-absorbing resin particles (2-1) Water absorption amount The water absorption was measured in a room adjusted to 25°C ± 1°C. 500g of physiological saline was weighed into a 500mL beaker, and a stirrer bar (8mmφ × 30mm, without a ring) was placed inside. The beaker was placed on a magnetic stirrer and 2.0g of superabsorbent polymer particles were dispersed while stirring at 600 r / min, ensuring that no clumps formed. This was left to stand for 60 minutes to allow the polymer particles to swell sufficiently. The contents of the beaker were then filtered using a 75μm mesh standard sieve (mass Wa [g]). The sieve was tilted at an angle of approximately 30 degrees to the horizontal and left for 30 minutes to filter out excess water from the swollen gel on the sieve. The total mass Wb [g] of the sieve and the swollen gel on the sieve was then measured, and the amount of physiological saline absorbed by the polymer particles was calculated using the following formula. The results are shown in Table 1. Water absorption amount [g / g]=(Wb-Wa) / 2.0

[0137] (2-2) Water retention The water retention capacity was measured in a room adjusted to 25°C ± 1°C. A cotton bag (membrane #60, 100mm wide x 200mm long) containing 2.0g of superabsorbent polymer particles was placed in a 500mL beaker. 500g of 0.9% by mass sodium chloride aqueous solution (physiological saline) was poured into the cotton bag containing the superabsorbent polymer particles in one go, taking care not to cause spillage. The top of the cotton bag was then tied with a rubber band and left to stand for 30 minutes to allow the polymer particles to swell. After 30 minutes, the cotton bag was dewatered for 1 minute using a dehydrator (manufactured by Kokusan Co., Ltd., model number: H-122) set to a centrifugal force of 167G. The mass Wa [g] of the cotton bag containing the swollen gel after dewatering was measured. The same procedure was performed without adding superabsorbent polymer particles, and the empty mass Wb [g] of the cotton bag when wet was measured. The water retention capacity of the superabsorbent polymer particles in physiological saline was calculated using the following formula. The results are shown in Table 1. Water retention amount [g / g]=(Wa-Wb) / 2.0

[0138] (2-3) Water absorption rate The water absorption rate was measured in a room adjusted to 25°C ± 1°C. 50 ± 0.1 g of physiological saline was weighed into a 100 mL beaker, a magnetic stirrer bar (8 mmφ × 30 mm, without a ring) was placed inside, and the beaker was immersed in a constant temperature water bath to adjust the liquid temperature to 25 ± 0.2°C. Next, the beaker was placed on a magnetic stirrer and rotated at 600 r / min to generate a vortex in the physiological saline. Then, 2.0 ± 0.002 g of superabsorbent polymer particles were quickly added to the beaker, and the time (seconds) from the addition of the polymer until the vortex on the liquid surface subsided was measured using a stopwatch, and this was defined as the water absorption rate of the polymer particles. The results are shown in Table 1.

[0139] (2-4) Medium particle size JIS standard sieves were assembled in the following order from top to bottom: a sieve with a mesh size of 600 μm, a sieve with a mesh size of 500 μm, a sieve with a mesh size of 425 μm, a sieve with a mesh size of 300 μm, a sieve with a mesh size of 250 μm, a sieve with a mesh size of 180 μm, a sieve with a mesh size of 150 μm, and a receiving tray. 50 g of superabsorbent polymer particles were placed in the top sieve and classified by shaking for 10 minutes using a rotary shaker. After classification, the mass of the particles remaining on each sieve was calculated as a mass percentage of the total amount to determine the particle size distribution. The relationship between the sieve mesh size and the accumulated mass percentage of the particles remaining on the sieve was plotted on logarithmic probability paper by accumulating the mass on the sieves in order from the largest particle size. By connecting the plots on probability paper with straight lines, the particle size corresponding to a cumulative mass percentage of 50% was obtained as the median particle size. The results are shown in Table 1 (the median particle sizes for SAPb, SAPd, and SAPe are as described in (1) above).

[0140] (3) Preparation of the intermediate sheet Prepare the following nonwoven fabric and cut it into a shape with a long side (a rectangle measuring 10cm x 40cm). • Air-through nonwoven fabric a (Guangzhou Jinhan Nonwoven Fabric Co., Ltd., D45-200, basis weight 45g / m²) 2 ) ·Air-through non-woven fabric B (Jiangsu Hualong Non-woven Fabric Co., Ltd., basis weight 32g / m 2 ) ·Air-through non-woven fabric c (Jiangsu Hualong Non-woven Fabric Co., Ltd., basis weight 45g / m 2 ) • Spunlace nonwoven fabric (Kuraray Co., Ltd., 70% rayon; 20% PET; 10% PP / PE, basis weight 35g / m²) 2 ) ·Spunbond nonwoven fabric (Toray Koxin Juhua (Nantong) Co., Ltd., LIVSEN Waterproof SSSS, basis weight 17g / m 2 )

[0141] (3-1) Processing of air-through nonwoven fabric a The following processing was performed on air-through nonwoven fabric a to obtain four types of nonwoven fabrics with different shapes for region A and region B.

[0142] (3-1-1) Using a heat sealer (Fuji Impulse Co., Ltd., FI-450-5, time setting 3-5) on the air-through nonwoven fabric a, a heat seal embossing method was used to form the embossed area (processed area) Bh-, and the remaining area (unprocessed area) was designated as the Al+ area. Specifically, as shown in Figure 12, 19 linear areas Bh- (embossed areas) with a width of approximately 5 mm were formed at intervals of approximately 2 cm in a direction parallel to the short direction of the nonwoven fabric, thereby obtaining linear areas Al+ in a direction parallel to the short direction of the nonwoven fabric. The resulting processed air-through nonwoven fabric a had the form of the intermediate sheet 30c shown in Figure 9.

[0143] (3-1-2) As shown in Figure 13, 12 linear regions Bh- (embossed areas) and 3 regions B' (high-density, concave embossed areas), each approximately 5 mm wide, were formed in a grid pattern at approximately 3 cm intervals in the direction parallel to the short direction and the direction parallel to the long direction of the nonwoven fabric. The resulting processed air-through nonwoven fabric a had the form of the intermediate sheet 30c shown in Figure 9.

[0144] (3-1-3) As shown in Figure 14, the same procedure as in (3-1-1) was performed, except that linear regions Bh- (embossed areas) with a width of approximately 5 mm were formed at intervals of approximately 2 cm in a direction parallel to the longitudinal direction of the nonwoven fabric, thereby obtaining linear regions Al+ in a direction parallel to the longitudinal direction of the nonwoven fabric. The resulting processed air-through nonwoven fabric a had the form of the intermediate sheet 30c shown in Figure 9.

[0145] (3-1-4) As shown in Figure 15, the same procedure as in (3-1-1) was performed, except that 15 linear regions Bh- (embossed areas) with a width of approximately 5 mm and an angle of 45° to the longitudinal direction of the nonwoven fabric were formed at intervals of approximately 3 cm, thereby obtaining linear regions Al+ at a 45° angle to the longitudinal direction of the nonwoven fabric. The resulting processed air-through nonwoven fabric a had the form of the intermediate sheet 30c shown in Figure 9.

[0146] (3-2) Processing of air-through nonwoven fabric b The same processing as described in (3-1-1) above was performed. The resulting processed air-through nonwoven fabric b had the form of an intermediate sheet 30c as shown in Figure 9.

[0147] (3-3) Processing of air-through nonwoven fabric c The same processing as described in (3-1-1) above was performed. The resulting processed air-through nonwoven fabric c had the form of an intermediate sheet 30c as shown in Figure 9.

[0148] (3-4) Processing of spunlace nonwoven fabric The same processing as described in (3-1-1) above was performed. The resulting processed spunlace nonwoven fabric had the form of an intermediate sheet 30c as shown in Figure 9.

[0149] (3-5) Processing of spunbond nonwoven fabric The same processing as described in (3-1-1) above was performed. The resulting processed spunbond nonwoven fabric had virtually no difference in density between the processed and unprocessed areas, and its surface was flush.

[0150] (4) Measurement of the intermediate sheet Thickness of region A (mm), height of region A (mm), density of region A (kg / m³) 3 The density ratio of region A to the density of region B (which is set to 1), and the area percentage (%) of region B were measured. The results are shown in Table 1.

[0151] (4-1) Thickness of region A The thickness was measured by lightly clamping area A once with a thickness measuring instrument (Dial Thickness Gauge JB, manufactured by Ozaki Seisakusho Co., Ltd.).

[0152] (4-2) Height of area A The thickness of region B was measured in the same manner as in (4-1), and the difference between the thickness of region B and region A was derived. Half of this difference (1 / 2) was taken as the height of region A.

[0153] (4-3) Density of region A (kg / m³) 3 ) The basis weight of the nonwoven fabric used as the intermediate sheet material was calculated by dividing it by the thickness of region A.

[0154] (5) Fabrication of the laminate (5-1) Structure of the laminate A laminate was prepared by stacking a first sheet, a water-absorbent resin layer, an adhesive layer, an intermediate sheet, another water-absorbent resin layer, an adhesive layer, and a second sheet in this order.

[0155] (5-2) Material • Absorbent resin particles for water-absorbent resin layers and other water-absorbent resin layers (Examples 1-7 and Comparative Examples 1-10) SAPa synthesized in manufacturing example 1 • SAPb synthesized in manufacturing example 2 • SAPc synthesized in manufacturing example 3 • SAPd synthesized in manufacturing example 4 SAPe synthesized in manufacturing example 5

[0156] • Intermediate sheets (Examples 1-7 and Comparative Examples 3, 4, and 9) Processed air-through nonwoven fabric (2cm spacing along the length) Processed air-through nonwoven fabric (2cm spacing in the short direction) Processed air-through nonwoven fabric (3cm grid pattern) Processed air-through nonwoven fabric (2cm spacing along the length) Processed air-through nonwoven fabric (3cm spacing at 45° angles) Processed air-through nonwoven fabric (2cm spacing in the short direction) Processed air-through nonwoven fabric (2cm spacing in the short direction) Processed spunlace nonwoven fabric (2cm spacing in the short direction) Processed spunbond nonwoven fabric (2cm spacing in the short direction) • Intermediate sheets (Comparative examples 1, 2, 5, 6, 7, 8, 10) Unprocessed, air-through nonwoven fabric Unprocessed air-through nonwoven fabric Unprocessed, air-through nonwoven fabric Unprocessed spunlace nonwoven fabric Unprocessed spunbond nonwoven fabric

[0157] • First and second sheets (Examples 1-7 and Comparative Examples 1-10) Airlaid nonwoven fabric (KNH Enterprise Co., Ltd., 6190516-1A01, basis weight 40g / m²) 2 )

[0158] ·Adhesive layer Hot melt adhesive (Henkel Japan Ltd., softening point 96℃, TECHNOMELT DM5912)

[0159] (5-3) Manufacturing method A first and second sheet (both made of the same material) were prepared, cut to 14cm x 42cm. Using a hot melt coating machine (Harries Co., Ltd., pump: Marshal150, table: XA-DT, tank temperature setting: 150℃, hose temperature setting: 165℃, gun head temperature setting: 170℃), 0.2g of hot melt adhesive was applied to the intermediate sheet in 10 lines at 10mm intervals along the longitudinal direction of the intermediate sheet as shown in Table 1. The adhesive application pattern was a spiral stripe. The intermediate sheet was then placed so that the side without adhesive was in contact with the second sheet, with the substrate for the second sheet exposed at 2cm on each side (from the short end) and 1cm on each side (from the long end). Furthermore, using an airflow mixing device (Autec Co., Ltd., pad former), a total of 7.2g of SAP for the water-absorbent resin layer shown in Table 1 was uniformly scattered onto the intermediate sheet to laminate the water-absorbent resin layer. Next, the first sheet was placed on the side of the water-absorbent resin layer of the intermediate sheet, sandwiched between release paper from above and below, and pressed together using a laminating machine (Hashima Co., Ltd., Straight Linear Fussing Press, Model HP-600LFS, 110℃, 0.1MPa). The release paper was then removed to obtain a laminated material in which the first sheet, the water-absorbent resin layer, and the intermediate sheet were bonded together.

[0160] After inverting the obtained laminated material vertically, the second sheet was gently peeled off the intermediate sheet, and a total of 7.2 g of SAP for the other water-absorbing resin layers shown in Table 1 was uniformly scattered onto the intermediate sheet of the laminated material using an air-flow mixing device, and the other water-absorbing resin layers were laminated. Fourteen lines of hot-melt adhesive were applied at 10 mm intervals to the surface of the peeled second sheet that had been in contact with the intermediate sheet, using the same method as above. Then, the second sheet was laminated so that the adhesive layer faced the other water-absorbing resin layers, all layers were sandwiched with release paper, pressed and bonded using a laminating machine, the release paper was removed, and the desired laminate was obtained.

[0161] (6) Evaluation of the laminate (6-1) Test solution A test solution having the following composition was prepared. • Ion-exchanged water: 9865.75g NaCl: 100.0g CaCl2·2H2O: 3.0g MgCl2·6H2O: 6.0g Triton X-100 (1%): 25.0g ·Food Blue No. 1 (for coloring): 0.25g

[0162] (6-2) Leakage prevention from the short end Using the apparatus shown in Figure 16, a leak prevention test was performed on the short end of the fabricated laminate (hereinafter also referred to as "laminated laminate 10x"). The apparatus shown in Figure 16 is as follows: an acrylic plate 92 is fixed at an angle using a commercially available experimental equipment stand 91, and the laminate 10x is placed on the plate with one short end SE facing downwards. The test liquid is then poured into the laminate 10x from vertically above using a dropping funnel 93, and the amount of leakage from the short end SE is measured using a balance 94.

[0163] The apparatus shown in Figure 16 will be described in more detail. The acrylic plate 92 has a length of 45 cm in the direction of the inclined surface and is fixed by the stand 1 so that the angle it makes with the horizontal is 45 ± 2°. Since the surface of the acrylic plate 92 is smooth, liquid does not accumulate on the plate. Using the stand 91, a dropping funnel (300 mL capacity dropping funnel manufactured by Cosmosbead Co., Ltd.) 93 is fixed to the vertically upper side of the inclined acrylic plate 92. The inner diameter of the tip of the dropping funnel 93 is approximately 4 mmφ, and the stopcock was adjusted so that the liquid is dispensed at a rate of 8 mL / second. A balance 94 with a metal tray 95 placed on top is set up below the acrylic plate 92, and is prepared to receive all of the test liquid that flows out as leakage and to record its mass with an accuracy of 0.1 g.

[0164] Leak prevention tests on inclines using such equipment were performed according to the following procedure: Air-through nonwoven fabric (Rengo Nonwoven Products Co., Ltd., material composition: 50% PP and 50% PE, basis weight: 21 g / m²) was placed as a top sheet on top of the fabricated 10x laminate. 2After placing the laminated body 10x on the acrylic plate 92 and measuring its mass, the prepared laminated body 10x was attached to the acrylic plate 92 using cloth tape so that one of its short ends SE was facing downwards (to minimize errors in leakage and to avoid obstructing the flow path of the liquid, the lower end, i.e., the short end SE, of the prepared laminated body 10x was not attached). Next, a mark was made 28 cm above the short end SE of the lower laminated body 10x in the longitudinal direction of the laminated body 10x and at the center in the short direction.

[0165] The opening of the dropping funnel 93 was fixed so that it was 10±1 mm vertically above the mark. The balance 94 was started and the display was corrected to zero. Then, 80 mL of the test solution, which had been pre-adjusted to 25±1°C, was poured into the dropping funnel 93 all at once and allowed to drip onto the mark on the laminate 10x over 10 seconds. The mass of the test solution that flowed down the inclined acrylic plate 92 without being absorbed by the laminate 10x and was collected in the metal tray 95 was recorded. At 10-minute intervals from the start of the first pour, the test solution was poured and the mass of the test solution collected in the metal tray 95 was measured in the same manner, and this was repeated a total of 5 times.

[0166] The total mass of the test liquid collected in the metal tray during the five injections of the test liquid was defined as the "leakage from the short end [g]". The results are shown in Table 1. A smaller leakage amount indicates better resistance to leakage in the inclined direction.

[0167] Furthermore, the "leak prevention improvement score" was defined as the relative values ​​of the leakage amounts in Examples 1, 2, 3, 4, Comparative Examples 3, 4, Examples 5, 6, 7, and Comparative Example 9, which used processed intermediate sheets, compared to the leakage amounts in Comparative Examples 1, 2, 5, 6, 7, 8, and 10, which used unprocessed intermediate sheets, with each leakage amount set to 1. The results are shown in Table 1. A smaller leak prevention improvement score indicates a better effect in improving leakage prevention in the inclined direction.

[0168] [Table 1] [Explanation of symbols]

[0169] 10, 10a, 10x… Laminate 10',10'a...Laminated material in a state of absorbing liquid 20…First sheet 30, 30a, 30b, 30c, 30d… Intermediate sheets 40...2nd seat 51...Water absorbent resin layer 51'...Water-absorbing resin layer in a water-absorbent state 52...Other water-absorbing resin layers A…Area A Al…Low density area A+...Convex region Al+... Low density / convex region LD-B...Longest direction of region B B…Area B Bh…High density area B-... recessed area Bh-...High density / recessed region LD-B...Longest direction of region B L... A straight line connecting one end of region B in the direction of extension to the other end. LMD10...Lamination direction of the laminate LD…(The longitudinal direction of the laminate, first sheet, water-absorbing resin layer, intermediate sheet, and second sheet) SD…(Laminate, first sheet, superabsorbent resin layer, intermediate sheet, second sheet) Short direction LE…Long end SE…Short end M... Longitudinal center line

Claims

1. A laminate comprising a liquid-permeable first sheet, a liquid-absorbing intermediate sheet, and a second sheet, each having a longitudinal shape, and a water-absorbing resin layer interposed at least between the first sheet and the intermediate sheet, The intermediate sheet includes region A and region B having a longitudinal shape, The water-absorbing resin layer is laminated in the regions A and B of the intermediate sheet. A laminate in which region A and region B satisfy at least one of the following relationships (1) and (2), and also satisfy the following relationship (3): (1) Region A is low density and region B is high density, and the ratio of the density of region A to the density of region B (where the density of region B is 1) is 0.05 or more and 0.6 or less. (2) The region A is a convex portion that protrudes toward the water-absorbent resin layer and the region B is a concave portion, and the height of the convex portion is 0.25 mm or more. (3) The region B extends inward from both short ends of the intermediate sheet, crossing between both long ends, and the straight line connecting one end of the region B in the direction of extension to the other is substantially parallel to the short direction of the intermediate sheet.

2. The laminate according to claim 1, wherein region A and region B satisfy the relationship described in (1) and (2) above.

3. The laminate according to claim 1 or 2, wherein the region B extends substantially parallel to the short direction of the intermediate sheet.

4. The laminate according to claim 3, wherein the region B includes a linear portion arranged on the longitudinal center line of the intermediate sheet.

5. The laminate according to any one of claims 1 to 4, wherein multiple regions A and B are arranged alternately in the short direction of those regions.

6. The laminate according to claim 5, comprising linear portions in which multiple regions A and B are arranged in parallel.

7. The laminate according to any one of claims 1 to 6, wherein both ends of the region A in the extending direction are located inward from the longitudinal end of the intermediate sheet.

8. The laminate according to any one of claims 1 to 7, wherein the thickness of region A of the intermediate sheet is 0.7 mm or more.

9. The laminate according to any one of claims 1 to 8, further comprising another region B' extending in a direction including the longitudinal direction of the intermediate sheet, wherein the other region B' is high density and / or recessed, the ratio of the density of region A to the density of region B' being 1 is 0.6 or less, and / or the height of the protrusion is 0.25 mm or more.

10. An absorbent article comprising a laminate according to any one of claims 1 to 9.

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