Composite absorbent and sanitary article

Abstract

Provided is an absorbent that can effectively absorb a body fluid and has excellent absorbency. A composite absorbent (4) according to the present application is a composite absorbent for a sanitary product for absorbing a body fluid, and includes a particulate high-molecular absorbent having a continuous skeleton and a continuous void, the high-molecular absorbent having a particle diameter of 300 μm or more.

Description

Technical Field

[0001] This invention relates to composite absorbents and sanitary products having the same. Background Technology

[0002] For hygiene products such as disposable diapers and sanitary napkins, porous materials such as sponge materials are known to be used as absorbent materials. For example, Patent Document 1 discloses an absorbent article comprising a polymer foam material formed from a hydrophilic flexible structure of interconnected continuous air bubbles.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 3231320 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] This porous material is sometimes used in particulate form to more effectively absorb bodily fluids. However, if the particle size is reduced, the fine pore structure of the porous material is distorted, and the absorption performance of bodily fluids may decrease.

[0008] The present invention was made in view of this problem, and its object is to provide an absorbent that can effectively absorb bodily fluids and has excellent absorption performance.

[0009] Solution for solving the problem

[0010] One aspect of the present invention (Aspect 1) is a composite absorbent, characterized in that it is a composite absorbent for use in sanitary products for absorbing bodily fluids.

[0011] The composite absorber comprises: a particulate polymeric absorbent with a hydrophilic continuous framework and continuous pores.

[0012] The aforementioned polymeric absorbent has a particle size of over 300 μm.

[0013] The composite absorbent of this method 1 is a particulate polymer absorbent with a particle size of more than 300 μm that can introduce body fluid into continuous pores by utilizing capillary phenomenon. It easily maintains the fine pore structure with the above-mentioned continuous skeleton and continuous pores, so it can effectively absorb body fluid and exert excellent absorption performance.

[0014] In addition, another aspect (mean 2) of the present invention is characterized in that, in the composite absorbent of the above-mentioned means 1, the volume increase rate of the aforementioned polymer absorbent during saturation absorption relative to the volume before absorption is 233% to 567%.

[0015] The composite absorbent of this method 2 can absorb body fluids more effectively and exhibit further superior absorption performance because the volume increase rate of the polymer absorbent during liquid absorption is 233% to 567%.

[0016] The present invention is further characterized in that, in the composite absorber of the above-mentioned method 1 or 2, the porosity per unit volume of the aforementioned polymer absorbent is 85% or more.

[0017] The composite absorbent of this method 3 has a porosity of over 85% per unit volume of polymer absorbent, thus it can absorb more body fluids and exhibit even better absorption performance.

[0018] The present invention is further characterized in that, in any of the composite absorbers of embodiments 1 to 3 above, the average diameter of the aforementioned continuous pores is 1 μm to 1000 μm.

[0019] The composite absorbent of this method 4 has an average diameter of 1μm to 1000μm for continuous pores of the polymer absorbent. Not only are the spaces (pores) of the polymer absorbent used to introduce body fluids not easily damaged, but it can also have a higher absorption rate and can stably exert excellent absorption performance.

[0020] The further embodiment of the present invention (e.g., embodiment 5) is characterized in that, in the composite absorbent of any one of embodiments 1 to 4 above, the aforementioned polymeric absorbent is a monolithic absorbent.

[0021] The composite absorbent of this method 5, because the polymer absorbent is a monolithic column absorbent, can not only quickly absorb body fluids, but also deliver temporarily held body fluids more firmly to SAP.

[0022] The further embodiment of the present invention (e.g., embodiment 6) is characterized in that, in the composite absorbent of any one of embodiments 1 to 5, the aforementioned polymer absorbent is a hydrolysate of a cross-linked polymer of (meth)acrylate and a compound containing two or more vinyl groups, and contains at least one -COONa group.

[0023] The composite absorbent of this method 6 has the above-mentioned specific composition through the polymer absorbent. When absorbing body fluid, the hydrophilic continuous skeleton is easy to elongate and the continuous pores are easy to expand. Therefore, more body fluid can be introduced into the continuous pores more quickly, and as an absorbent, it can exert a further excellent absorption performance.

[0024] In addition, another aspect (mean 7) of the present invention is a hygiene product characterized by having a composite absorbent of any one of the above-described means 1 to 6.

[0025] The sanitary product of this method 7, having a composite absorbent body of any one of the methods 1 to 6 above, can effectively absorb body fluids and exhibit excellent absorbency.

[0026] The effects of the invention

[0027] According to the present invention, an absorbent that can effectively absorb bodily fluids and has excellent absorption performance can be provided. Attached Figure Description

[0028] Figure 1 This is a schematic top view of the light incontinence pad 1 as seen from the side opposite the skin in the thickness direction.

[0029] Figure 2 The diagram illustrates the manufacturing process of absorbent A, an example of a polymeric absorbent.

[0030] Figure 3 This is a SEM image of absorbent A at 50x magnification.

[0031] Figure 4 This is a SEM image of absorbent A at 100x magnification.

[0032] Figure 5 This is a SEM image of absorbent A at 500x magnification.

[0033] Figure 6 This is a SEM image of absorbent A at 1000x magnification.

[0034] Figure 7 This is a SEM image of absorbent A at 1500x magnification. Detailed Implementation

[0035] The preferred embodiment of the composite absorbent of the present invention will be described in detail below using a light incontinence pad 1 as an example of a sanitary product to which the composite absorbent is applied.

[0036] It should be noted that, unless otherwise specified, in this instruction manual, "the view of an object placed horizontally in its unfolded state from the vertical top side (the surface side when the object is a sanitary product) in the thickness direction of the object (e.g., incontinence pads, composite absorbents, etc.)" will be referred to only as "top view".

[0037] It should be noted that in this specification, "length direction" refers to "the direction of the longer length of an object in a top view (such as a light incontinence pad, composite absorbent, etc. in an unfolded state)," "width direction" refers to "the direction of the shorter length of an object in a top view," and "thickness direction" refers to "the direction perpendicular to an object placed on a horizontal surface in an unfolded state." These length, width, and thickness directions are all orthogonal to each other.

[0038] In addition, unless otherwise specified in this instruction manual, in the thickness direction of the incontinence pad 1, the side "proximal to the wearer's skin when wearing the incontinence pad 1" is referred to as the "skin-opposing side", and the side "far from the wearer's skin when wearing the incontinence pad 1" is referred to as the "non-skin-opposing side".

[0039] [Minor Incontinence Pad]

[0040] Figure 1 A schematic top view of the light incontinence pad 1 in its unfolded state, according to an embodiment of the present invention, of the composite absorbent 4.

[0041] like Figure 1 As shown, when viewed from above, the incontinence pad 1 has a longitudinally elongated shape with a length direction L and a width direction W, and two longitudinally elongated end edges protruding outward in an arc shape along the length direction. It should be noted that the shape of the incontinence pad 1 is not limited to this type. If it is longitudinally elongated, it can adopt any shape (e.g., oblong, rectangular, hourglass, etc.) depending on various uses and methods of use.

[0042] The incontinence pad 1 has a liquid-permeable surface sheet 2 forming the skin-facing side of the incontinence pad 1 in the thickness direction, a back sheet 3 forming the non-skin-facing side of the incontinence pad 1, and a composite absorbent body 4 located between these sheets as its basic components.

[0043] In addition, the incontinence pad 1 also has a surface disposed on the non-skin-facing side of the back panel 3, and an adhesive part (not shown) for adhering and fixing the incontinence pad 1 to the inner surface of the wearer's underwear or other clothing.

[0044] It should be noted that the incontinence pad 1 is not limited to this configuration. For example, it may have a pair of side sheets for forming a leak-proof wall, which are arranged at both ends of the incontinence pad 1 in the width direction W and extend in the length direction L, compared with the surface sheet 2 on the skin-opposing side; and multiple elastic members arranged in the length direction L of the pair of side sheets respectively.

[0045] Furthermore, in the incontinence pad 1, the composite absorbent 4 is located between the surface sheet 2 and the back sheet 3 and is formed by a water-absorbing component capable of absorbing bodily fluids such as urine that are excreted by the wearer and pass through the surface sheet 2. The composite absorbent 4 includes a particulate polymer absorbent with a particle size of 300 μm or more, having a hydrophilic continuous skeleton and continuous pores.

[0046] This polymeric absorbent utilizes capillary action to introduce bodily fluids into continuous pores, resulting in a specific particle size of over 300 μm. This allows it to easily maintain the aforementioned microporous structure with a continuous framework and continuous pores, thus effectively absorbing bodily fluids and exhibiting excellent absorption performance. Therefore, the composite absorbent 4 containing the aforementioned polymeric absorbent can function as an absorbent and exhibit excellent absorption performance.

[0047] Therefore, in addition, the incontinence pad 1 with this composite absorbent 4 can also effectively absorb body fluids as an incontinence pad and can exert excellent absorption performance.

[0048] It should be noted that the particle size of the polymer absorbent is as described below.

[0049] The following describes in detail the various constituent components of sanitary products to which the composite absorbent of the present invention is applicable, using the above-described light incontinence pad 1.

[0050] (Surface sheet)

[0051] In the aforementioned mild incontinence pad 1, such as Figure 1 As shown, the surface sheet 2 has a longitudinally elongated shape, extending from one end edge in the length direction L of the incontinence pad 1 to the other end edge, and from near one end edge in the width direction W of the incontinence pad 1 to near the other end edge, when viewed from above. The surface sheet 2 is a liquid-permeable sheet-like member formed by being positioned in the thickness direction of the incontinence pad 1 on the skin-facing side, creating a contact surface that can abut against the wearer's skin, i.e., the skin-facing side surface of the incontinence pad 1.

[0052] In addition, such as Figure 1 As shown, the surface sheet 2 has a slightly larger size in the length direction L and width direction W compared to the composite absorber 4 disposed on the non-skin-facing side of the surface sheet 2, and is joined to the back sheet 3 located on the non-skin-facing side in the periphery.

[0053] In this invention, there are no particular restrictions on the shape, size, weight, etc. of the surface sheet, as long as it can be used as a surface sheet for hygiene products. Any shape, size, weight, etc. can be adopted that corresponds to the desired liquid permeability, skin feel, softness, strength, etc.

[0054] (Back panel)

[0055] In the aforementioned incontinence pad 1, the back panel 3 has an elongated shape that, when viewed from above, extends from one end edge in the length direction L of the incontinence pad 1 to the other end edge, and also extends from one end edge in the width direction W of the incontinence pad 1 to the other end edge. The back panel 3 is a non-permeable sheet member disposed in the thickness direction of the incontinence pad 1 on the non-skin-facing side, forming the non-skin-facing surface of the incontinence pad 1, and preventing leakage of bodily fluids such as urine through the composite absorbent 4 to the outside of the incontinence pad 1.

[0056] In this invention, there are no particular restrictions on the shape, size, weight, etc. of the back sheet, as long as it can be used as the back sheet of a sanitary product. Any shape, size, weight, etc. can be adopted that corresponds to the desired leak-proof performance, breathability, strength, etc.

[0057] (Complex absorber)

[0058] In the aforementioned mild incontinence pad 1, such as Figure 1 As shown, the composite absorbent 4 has the following longitudinal shape when viewed from above: it extends in a wide region along the length direction L from near one end edge to near the other end edge, with the center portion of the light incontinence pad 1 in the length direction L as the center, and also extends in a wide region along the width direction W from near one end edge to near the other end edge, and the two ends in the length direction protrude outward in an arc shape.

[0059] More specifically, when viewed from above, the composite absorber 4 has a tapered portion in the middle of its length direction that is relatively smaller in the width direction compared to other parts, and further includes a minimum width portion in which the composite absorber 4 has the minimum width in the tapered portion, and a maximum width portion in which the composite absorber 4 has the maximum width on the outer side of the tapered portion in the length direction.

[0060] The composite absorbent 4 is formed by a defined absorbent component disposed between the surface sheet 2 and the back sheet 3 in the thickness direction of the light incontinence pad 1, capable of absorbing and retaining bodily fluids such as urine that permeate through the surface sheet 2. This absorbent component is composed of absorbent materials such as polymeric absorbents, hydrophilic fibers, and highly absorbent polymers (described later), and sheets such as thin paper that hold it in place. In other words, the composite absorbent refers to an absorbent component composed of absorbent materials capable of absorbing and retaining bodily fluids, and sheets that hold them in place.

[0061] It should be noted that in the light incontinence pad 1, the composite absorbent 4 is bonded to the surface sheet 2 and the back sheet 3 using any adhesive such as a hot melt adhesive.

[0062] Furthermore, the composite absorber 4 comprises a polymeric absorbent with a specific particle size, having a hydrophilic continuous framework and continuous pores as described above. This polymeric absorbent is described below.

[0063] It should be noted that the composite absorbent 4, as a water-absorbing material, may contain only the aforementioned polymeric absorbent, or it may contain, in addition to the aforementioned polymeric absorbent, other water-absorbing materials known in the art. Examples of such water-absorbing materials include, for instance, hydrophilic fibers and highly absorbent polymers. More specifically, examples include pulp fibers (e.g., crushed pulp), cotton, rayon, cellulose fibers such as acetate; granules formed from highly absorbent polymers (SAP) such as sodium acrylate copolymers; and mixtures formed by any combination of these materials.

[0064] It should be noted that the composite absorbent 4 has a structure in which the polymer absorbent and water-absorbing material are covered by a coating sheet such as hydrophilic paper.

[0065] In this invention, the shape, size, and weight of the composite absorbent are not particularly limited as long as they do not hinder the effect of the invention. Any shape, size, and weight corresponding to the desired absorbency, softness, strength, etc., can be adopted.

[0066] The polymeric absorbent used in the composite absorbent of the present invention will be described in more detail below.

[0067] [Polymer absorbent]

[0068] If the polymeric absorbent is a particulate polymeric absorbent with a specific particle size of 300 μm or more and possessing a hydrophilic continuous backbone and continuous pores, it is not particularly limited. For example, it can be a hydrolysate of a cross-linked polymer containing at least two monomers of (meth)acrylate, and examples include polymeric compounds having at least one hydrophilic group in their functional groups. More specifically, it can be a hydrolysate of a cross-linked polymer of (meth)acrylate and a compound containing two or more vinyl groups per molecule, and examples include polymeric compounds having at least a -COONa group. The aforementioned polymeric absorbent is an organic porous body having at least one -COONa group per molecule, and may further have a -COOH group. The -COONa groups are distributed substantially uniformly in the framework of the porous body.

[0069] If the polymeric absorbent is a hydrolysate of a cross-linked polymer of (meth)acrylate and a compound containing two or more vinyl groups in one molecule, and contains at least one -COONa group, then when absorbing body fluids such as urine, the hydrophilic continuous skeleton is easy to elongate and the continuous pores are easy to expand. Therefore, more body fluid can be introduced into the continuous pores more quickly, and it can play a further excellent absorption role as an absorbent.

[0070] It should be noted that in this specification, (meth)acrylate refers to acrylate or methacrylate.

[0071] In the polymeric absorbent formed by the hydrolysis of this crosslinked polymer of (meth)acrylate and divinylbenzene, a hydrophilic continuous skeleton is formed by an organic polymer having at least -COONa groups, and there are connecting pores (continuous pores) between the skeletons that serve as absorption sites for the target fluid (i.e., urine and other bodily fluids).

[0072] It should be noted that hydrolysis treatment causes the -COOR groups (i.e., carboxylic acid ester groups) of the cross-linked polymer to form -COONa groups or -COOH groups (see reference). Figure 2 Therefore, polymeric absorbents can have -COOR groups.

[0073] The presence of -COOH and -COONa groups in organic polymers that form a hydrophilic continuous backbone can be confirmed by analysis using infrared spectrophotometry and quantitative methods for weakly acidic ion-exchange groups.

[0074] Here, Figure 2 This diagram illustrates the manufacturing process of absorbent A, an example of a polymeric absorbent. Figure 2 In the diagram, the top figure shows the constituent raw materials of the polymerization, the middle figure shows the monolithic column A as a crosslinked polymer of (meth)acrylate and divinylbenzene, and the bottom figure shows the absorbent A obtained by hydrolyzing and drying the monolithic column A in the middle figure.

[0075] The following description uses absorbent A, formed from the hydrolysate of a crosslinked polymer of (meth)acrylate and divinylbenzene, as an example of a polymer absorbent.

[0076] It should be noted that the polymer absorbent is not limited to absorbent A, but can also be a hydrolysate of a cross-linked polymer of (meth)acrylate and a compound having two or more vinyl groups in one molecule, or a hydrolysate of a cross-linked polymer containing at least two monomers of (meth)acrylate, etc.

[0077] It should be noted that in the following description, "monolithic column A" refers to an organic porous body formed by a cross-linked polymer of (meth)acrylate and divinylbenzene before hydrolysis treatment, sometimes referred to as "monolithic columnar organic porous body".

[0078] Additionally, "Absorbent A" is a hydrolysate of a cross-linked polymer (monolithic column A) of (meth)acrylate and divinylbenzene that has undergone hydrolysis and drying treatment. It should be noted that in the following description, Absorbent A refers to the absorbent in its dried state.

[0079] First, the structure of absorbent A will be explained.

[0080] As described above, absorbent A has a hydrophilic continuous backbone and continuous pores. Absorbent A is an organic polymer with a hydrophilic continuous backbone, such as... Figure 2 As shown, the cross-linked polymer (monolithic column A) is obtained by cross-linking (meth)acrylate as a polymerizing monomer and divinylbenzene as a cross-linking monomer, and then further hydrolyzing the resulting cross-linked polymer.

[0081] Organic polymers that form a hydrophilic continuous backbone, as structural units, have vinyl polymeric residues (hereinafter referred to as "structural unit X") and divinylbenzene crosslinked polymeric residues (hereinafter referred to as "structural unit Y").

[0082] Furthermore, the vinyl polymeric residues (structural unit X) in the organic polymer forming the hydrophilic continuous backbone have two types of groups: -COONa group, or -COOH group and -COONa group, generated by the hydrolysis of the carboxylic acid ester group. It should be noted that when the polymeric monomer is (meth)acrylate, the vinyl polymeric residues (structural unit X) have -COONa group, -COOH group and ester group.

[0083] In absorbent A, the ratio of cross-linked polymeric residues (structural unit Y) of divinylbenzene in the organic polymer forming a hydrophilic continuous backbone is, for example, 0.1 to 30 mol%, preferably 0.1 to 20 mol%, relative to all structural units. For example, in absorbent A where butyl methacrylate is used as the polymeric monomer and divinylbenzene is used as the cross-linking monomer, the ratio of cross-linked polymeric residues (structural unit Y) of divinylbenzene in the organic polymer forming a hydrophilic continuous backbone is, for example, about 3%, preferably 0.1 to 10 mol%, more preferably 0.3 to 8 mol%, relative to all structural units.

[0084] It should be noted that if the ratio of cross-linked polymer residues of divinylbenzene in the organic polymer forming the hydrophilic continuous backbone is 0.1 mol% or more, the strength of absorbent A is not easily reduced. In addition, if the ratio of cross-linked polymer residues of divinylbenzene is 30 mol% or less, the absorption amount of the target liquid is not easily reduced.

[0085] In addition, the organic polymer forming the hydrophilic continuous backbone in absorbent A may contain only structural units X and Y, or may contain polymer residues of monomers other than structural units X and Y, namely (meth)acrylate and divinylbenzene.

[0086] As structural units other than structural units X and Y, examples include polymer residues of monomers such as styrene, α-methylstyrene, vinyltoluene, vinyl benzyl chloride, glycidyl methacrylate, isobutylene, butadiene, isoprene, chloroprene, vinyl chloride, vinyl bromide, vinylidene chloride, tetrafluoroethylene, (meth)acrylonitrile, vinyl acetate, ethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate.

[0087] It should be noted that the ratio of structural units other than structural units X and Y in the organic polymer forming the hydrophilic continuous backbone is, for example, 0 to 50 mol%, preferably 0 to 30 mol%, relative to all structural units.

[0088] Furthermore, absorbent A preferably has a hydrophilic continuous framework with a thickness of 0.1 to 100 μm. If the thickness of the hydrophilic continuous framework of absorbent A is 0.1 μm or more, the spaces (pores) in the porous body used to introduce the target fluid (body fluid) are less likely to be damaged during absorption, and the absorption capacity is less likely to decrease. On the other hand, if the thickness of the hydrophilic continuous framework is 100 μm or less, an excellent absorption rate can be easily obtained.

[0089] It should be noted that the hydrophilic continuous framework of absorbent A has a continuous bubble structure, therefore the thickness of the continuous framework is measured at the cross-section of the framework appearing on the test piece used for electron microscopy. Since the continuous framework is formed by the spacing of water (droplets) removed through dehydration / drying after hydrolysis, it is mostly polygonal in shape. Therefore, the thickness of the continuous framework is set as the average value of the diameter (μm) of the circumcircle of the polygonal cross-section. In rare cases, small holes are formed within the polygon; in such cases, the circumcircle of the polygonal cross-section surrounding the small hole is measured.

[0090] Furthermore, absorbent A preferably has an average diameter of continuous pores ranging from 1 μm to 1000 μm. If the average diameter of the continuous pores in absorbent A is 1 μm or more, the spaces (pores) in the porous body used to introduce the target fluid (body fluid) are less likely to be damaged during absorption, and the absorption rate is less likely to decrease. On the other hand, if the average diameter of the continuous pores is 1000 μm or less, an excellent absorption rate is easily obtained. Thus, the composite absorbent containing this absorbent A can have a higher absorption rate and can stably exhibit excellent absorption performance.

[0091] It should be noted that the average diameter (μm) of the continuous pores in absorbent A can be determined using mercury intrusion porosimetry, employing the maximum value of the pore distribution curve obtained using this method. For the sample used to determine the average diameter of the continuous pores, regardless of the ionic form of absorbent A, a substance dried in a vacuum desiccator at a temperature set to 50°C for at least 18 hours is used as the sample. It should be noted that the ultimate limiting pressure is set to 0 Torr. Furthermore, the average diameter of the continuous pores in absorbent A is naturally smaller than the particle size of absorbent A.

[0092] Here, Figure 3 This is a SEM image of absorbent A at 50x magnification. Figure 4 This is a SEM image of absorbent A at 100x magnification. Figure 5 This is a SEM image of absorbent A at 500x magnification. Figure 6 A SEM image of absorbent A at 1000x magnification, and then... Figure 7 This is a SEM image of absorbent A at 1500x magnification.

[0093] These Figures 3 to 7 The absorbent A shown is an example of an absorbent in which butyl methacrylate is used as the polymer monomer and divinylbenzene is used as the crosslinking monomer. SEM images were taken using absorbents with a cubic structure of 2 mm square.

[0094] Figures 3 to 7 The absorbent A shown has numerous bubble-like macropores, and these bubble-like macropores overlap with each other. The overlapping portions of these macropores in absorbent A form a continuous bubble structure with common openings (mesopores), that is, a continuous bubble structure (continuous macroporous structure).

[0095] The overlapping portions of these macropores form common openings (mesopores) with an average diameter of 1–1000 μm, preferably 10–200 μm, and particularly preferably 20–100 μm in the dry state, and most of them form an open-pore structure. If the average diameter of the mesopores in the dry state is 1 μm or more, the absorption rate of the target liquid is better. On the other hand, if the average diameter of the mesopores in the dry state is 1000 μm or less, the absorbent A is less likely to become brittle.

[0096] It should be noted that the overlap of these large holes is about 1 to 12 for a single large hole, and mostly about 3 to 10.

[0097] Furthermore, since absorbent A has this continuous bubble structure, it has the advantage of being able to uniformly form macropore groups and mesopore groups, and compared with the particle-aggregated porous bodies described in Japanese Patent Application Publication No. 8-252579, it can significantly increase the pore volume and specific surface area.

[0098] It should be noted that the total pore volume of absorbent A is preferably 0.5–50 mL / g, more preferably 2–30 mL / g. If the total pore volume of absorbent A is 0.5 mL / g or more, the spaces (pores) in the porous body used to introduce the target fluid (body fluid) are less likely to be damaged during absorption, and the absorption capacity and absorption rate are less likely to decrease. On the other hand, if the total pore volume of absorbent A is 50 mL / g or less, the strength of absorbent A is less likely to decrease.

[0099] It should be noted that the total pore volume can be determined using mercury porosimetry. For the sample used in the determination of the total pore volume, regardless of the ionic form of absorbent A, the sample is dried in a vacuum desiccator at a temperature set to 50°C for at least 18 hours. It should be noted that the ultimate limiting pressure is set to 0 Torr.

[0100] The following describes the appearance of absorbent A in contact with bodily fluids (hereinafter referred to as "bodily fluids"). The same applies to the contact between the composite absorbent 4 containing absorbent A and bodily fluids. Furthermore, the mass of the absorbed bodily fluid is approximately proportional to the volume of the bodily fluid; therefore, in the following description, the mass of the bodily fluid will sometimes be referred to simply as the "volume of the bodily fluid."

[0101] first, Figures 3 to 7 The absorbent A shown has a continuous network of interconnected pores, which can be visually confirmed by the presence of numerous pores. When bodily fluid comes into contact with absorbent A, a certain amount of fluid enters these pores and is absorbed by absorbent A through capillary action. At this time, a portion of the absorbed bodily fluid is absorbed into the hydrophilic continuous framework through osmotic pressure, causing the framework to elongate. Conversely, the bodily fluid absorbed by absorbent A that is not absorbed into the hydrophilic continuous framework remains within the pores and is absorbed.

[0102] This absorbent A possesses the property of elongating its hydrophilic, continuous skeleton upon absorbing bodily fluids. This elongation of the continuous skeleton occurs in virtually all directions. Consequently, the shape of absorbent A increases due to this elongation of the continuous skeleton, and the size of each pore also increases. As the size of the pores increases, the volume within the pores increases, and therefore the amount of bodily fluid that can remain within the pores also increases.

[0103] In other words, the absorbent A, which increases in size by absorbing a certain amount of body fluid, can further absorb a specified amount of body fluid into the enlarged pores through capillary action.

[0104] Furthermore, absorbent A can rapidly absorb body fluids by absorbing them through capillary action.

[0105] Furthermore, compared to body fluids absorbed into the hydrophilic continuous framework, more body fluid remains within the pores when absorbed by absorbent A. Most of the body fluid absorption achieved using absorbent A occurs through capillary action, retaining the fluid within the pores. Therefore, a higher porosity (the volume of pores per unit volume of absorbent A relative to the total pore volume) indicates a greater capacity for body fluid absorption.

[0106] The porosity per unit volume of this polymeric absorbent is preferably 85% or more, more preferably 90% or more. If the porosity per unit volume of the polymeric absorbent is 85% or more, it can absorb more body fluids and exhibit even better absorption performance.

[0107] For example, if the above is obtained... Figures 3 to 7 The porosity of absorbent A shown is as follows.

[0108] Firstly, absorbent A, obtained using the mercury intrusion porosimetry method, has a specific surface area of ​​400 m². 2 / g, pore volume is 15.5mL / g. This pore volume of 15.5mL / g means that the volume of the pores in 1g of absorbent A is 15.5mL.

[0109] Here, if the specific gravity of absorbent A is assumed to be 1 g / mL, then the volume occupied by the micropores in 1 g of absorbent A, i.e., the micropore volume, is 15.5 mL. In addition, the volume of 1 g of absorbent A is 1 mL.

[0110] Therefore, the total volume of 1g of absorbent A is 15.5+1 (mL), and the ratio of the pore volume is the porosity. Thus, the porosity of absorbent A is 15.5 / (15.5+1)×100≒94%.

[0111] In this invention, the absorbent A, i.e., the polymer absorbent, which has such a hydrophilic continuous skeleton and continuous pores, is in the form of particles with a specific particle size of 300 μm or more, and is applied to the composite absorbent 4 of the above-mentioned incontinence pad 1 for absorbing body fluids such as urine.

[0112] The aforementioned polymeric absorbent can introduce body fluids into continuous pores through capillary action, thus having a specific particle size of over 300 μm. This makes it easy to maintain the fine pore structure with the aforementioned continuous framework and continuous pores, thereby effectively absorbing body fluids and exhibiting excellent absorption performance.

[0113] Therefore, the composite absorbent of the present invention containing this polymeric absorbent can effectively absorb body fluids and exhibit excellent absorption performance.

[0114] It should be noted that, considering absorption efficiency and wearing comfort (foreign body sensation), the particle size of the polymer absorbent is preferably below 2000 μm, more preferably 400 μm to 1500 μm. In particular, if the particle size of the polymer absorbent is above 400 μm, the number of pores inside the polymer absorbent particles can be ensured to be a certain level, allowing for the stable introduction of more target fluid (body fluid), that is, it can stably exert excellent water absorption.

[0115] In addition, the particle size of polymeric absorbents can be determined by sieving, which refers to the average particle size of particles classified using a sieve testing machine.

[0116] Here, we prepare to classify various polymeric absorbents with different particle sizes using a sieve tester, and determine the water absorption capacity of each polymeric absorbent with a different particle size according to the following test method. The results of the water absorption capacity determination are shown in Table 1 below.

[0117] <Method for Determining the Water Absorption Capacity of Polymer Absorbents>

[0118] (1) Seal 1g of the test sample (polymer absorbent) into a mesh bag cut into 10cm squares (manufactured by NBCMeshtec Inc., N-NO255HD 115 (standard width: 115cm, 255 meshes / 2.54cm, opening: 57μm, wire diameter: 43μm, thickness: 75μm)). It should be noted that the mass (g) of the mesh bag is measured beforehand. Furthermore, this test method is performed at a temperature of 25°C and a humidity of 60%. If the test sample (polymer absorbent) is recycled from a sanitary product, it can be obtained according to the <Recycling Method of Test Sample (Polymer Absorbent)> described later.

[0119] (2) Immerse the mesh bag containing the sample in physiological saline (0.9% sodium chloride aqueous solution) for 1 hour.

[0120] (3) Determine the mass (g) of the mesh bag after it has been suspended for 5 minutes to drain water.

[0121] (4) Subtract the mass of the sample (=1g) and the total mass of the mesh bag from the mass of the mesh bag after water control determined in (3) above, and calculate the water absorption (g) of the sample. Then divide the water absorption by the mass of the sample (=1g) to obtain the water absorption per unit mass of the sample (polymer absorbent) (g / g).

[0122] It should be noted that if the above-mentioned test sample (polymer absorbent) is recycled from the sanitary product, it can be obtained as follows.

[0123] <Method for recovering the sample (polymer absorbent) used in the determination>

[0124] (1) Peel off the surface sheet or other parts of the sanitary product to expose the composite absorbent.

[0125] (2) Allow the analyte (polymer absorbent) to fall from the exposed composite absorber, and use tweezers or the like to remove the (particulate) analyte other substances (such as pulp, synthetic resin fibers, etc.).

[0126] (3) As a means of magnified observation, a microscope or a simple magnifying glass is used to observe the sample at a magnification that allows for the recognition of the difference from SAP or to visually confirm the pores of the porous body. At the same time, tweezers or similar tools are used to retrieve the sample. It should be noted that the magnification of the simple magnifying glass is not particularly limited if it is a magnification that allows for visual confirmation of the pores of the porous body. For example, magnifications of 25x to 50x can be listed.

[0127] (4) The analytes recovered in this way are used as test samples in various test methods.

[0128] [Table 1]

[0129] Table 1

[0130]

[0131] As shown in Table 1, polymeric absorbents with hydrophilic continuous skeletons and continuous pores exhibit excellent water absorption even with small particle sizes such as 300 μm. Therefore, it can be seen that polymeric absorbents with particle sizes of 400 μm or more (more specifically 430 μm or more) consistently exhibit high water absorption.

[0132] Furthermore, as mentioned above, if bodily fluid enters the continuous pores of the polymeric absorbent through capillary action, a portion of the entered fluid is absorbed and the absorbent elongates due to osmotic pressure. The fluid is then further introduced into the expanded pores. In other words, the polymeric absorbent can swell (increase in volume) and further absorb bodily fluid (i.e., it can swell to further increase its water absorption / liquid retention capacity). Therefore, even if the polymeric absorbent is small in size and quantity before absorption (before swelling), it can effectively absorb more bodily fluid.

[0133] In particular, from the viewpoint of the absorption efficiency of such bodily fluids, the volume increase rate of the polymeric absorbent upon saturation absorption relative to its initial volume is preferably 233% to 567%. If the volume increase rate of the polymeric absorbent upon absorption is within this range, it can absorb bodily fluids more effectively and exhibit further superior absorption performance.

[0134] It should be noted that the volume increase rate of the polymer absorbent at saturation absorption relative to its initial volume can be determined as follows.

[0135] <Method for determining the volume increase rate of liquid during saturation aspiration relative to the initial volume>

[0136] (1) The sample (polymer absorbent) for testing is added to an acrylic cylinder (inner diameter: 26 mm, outer diameter: 38 mm, height: 80 mm, mass: 57 g) to which a nylon mesh material (manufactured by NBC Meshtec Inc., N-NO255HD 115 (standard width: 115 cm, 255 meshes / 2.54 cm, opening: 57 μm, wire diameter: 43 μm, thickness: 75 μm)) is adhered to the bottom surface. The height (mm) from the bottom surface of the cylinder to the top surface of the sample inside the cylinder is measured. It should be noted that if the top surface of the sample inside the cylinder is not flat, the height is measured up to the highest point (top). In addition, this test method is carried out under the conditions of 25°C and 60% humidity. Furthermore, if the sample (polymer absorbent) for testing is recycled from the sanitary product, it can be obtained according to the aforementioned <Recycling Method of Sample (Polymer Absorbent) for Testing>.

[0137] (2) Calculate the volume of the sample inside the cylinder, i.e., the volume before liquid absorption (mm³), from the measured height of the sample inside the cylinder and the bottom area of ​​the cylinder (π is set to 3.14). 3 ).

[0138] (3) Next, add 60 mL of physiological saline (0.9% sodium chloride aqueous solution) to the petri dish (inner diameter: 97 mm, mass: 58 g), place the cylinder containing the sample from (1) in the petri dish, immerse the bottom of the cylinder in physiological saline, and allow the physiological saline to absorb the sample in the cylinder.

[0139] (4) As the sample inside the cylinder absorbs physiological saline, the height (volume) of the sample inside the cylinder changes. Continuously observe the change in the height of the sample inside the cylinder. When the height does not change (i.e., until saturation), measure the height of the sample inside the cylinder (i.e., the height at saturation; mm). It should be noted that if the upper surface of the sample inside the cylinder is not flat at saturation, measure the height up to the highest point (top).

[0140] (5) Calculate the volume of the sample inside the cylinder during saturated absorption, i.e., the volume during saturated absorption (mm³), from the measured height of the sample inside the cylinder and the bottom area of ​​the cylinder (π is set to 3.14). 3 ).

[0141] (6) Divide the volume at saturation during absorption calculated in (5) above by the volume before absorption calculated in (2) above and multiply by 100 to obtain the volume increase rate (%) of the sample (polymer absorbent) at saturation during absorption relative to the volume before absorption.

[0142] Furthermore, in this invention, the polymeric absorbent preferably has the properties of applying 40 g / cm³. 2 It exhibits a specific water absorption property: the initial water absorption after 5 seconds of load is 5 g / g or more, and the water absorption after 20 seconds or more is 110% or more of the initial water absorption.

[0143] If a polymeric absorbent has this specific initial absorption capacity and absorption capacity after more than 20 seconds, then the absorption capacity in the initial stage of absorption is large, it can temporarily retain body fluids, and it can still absorb body fluids even after a specified time, thus it can exert a higher absorption performance.

[0144] Here, the aforementioned 40g / cm 2 This load is a load assuming normal body pressure. In addition, the water absorption after 20 seconds or more refers to the water absorption (mass; g / g) at any time after 20 seconds or more after the above load is applied under specified temperature conditions (e.g., after 20 seconds, after 60 seconds, after 300 seconds, after 3600 seconds, etc.).

[0145] It should be noted that the initial water absorption capacity and the water absorption capacity after a specified time of the polymer absorbent can be determined as follows.

[0146] <Method for determining the water absorption capacity of polymeric absorbents under specific loads>

[0147] (1) Add 25g of physiological saline (0.9% sodium chloride aqueous solution) to a petri dish with a base (inner diameter: 85mm, depth: 20mm, base configuration: two bases are arranged parallel to each other at a 24mm interval in the center of the bottom (inner surface side), base width: 2mm, base height: 2mm, base length: 25mm). It should be noted that this determination method is carried out under the conditions of 25℃ temperature and 60% humidity.

[0148] (2) Add 0.16g of the test sample (polymer absorbent) to a plastic cylinder (inner diameter: 26mm, outer diameter: 32mm, height: 33mm) with nylon mesh material (manufactured by NBC Meshtec Inc., N-NO255HD 115 (standard width: 115cm, 255 meshes / 2.54cm, opening: 57μm, wire diameter: 43μm, thickness: 75μm)) attached to the bottom surface, and spread it evenly. It should be noted that if the test sample (polymer absorbent) is recycled from the sanitary product, it can be obtained according to the aforementioned <Recycling Method for Test Sample (Polymer Absorbent)>.

[0149] (3) Place a cylindrical plastic piston (diameter: 25 mm, mass: 5 g) on ​​the sample inside the cylinder, and then place a specified mass (200 g; load 40 g / cm) on the plastic piston. 2 The mass (g) of the cylinder is determined using weights.

[0150] (4) Place the cylinder containing the sample, plastic piston and weights on the base in the center of the petri dish, and immerse the bottom of the cylinder in physiological saline so that the sample inside the cylinder absorbs the physiological saline.

[0151] (5) After a specified time (e.g., after 5 seconds, after 20 seconds, after 60 seconds, after 300 seconds, after 3600 seconds, etc.), lift the cylinder, tilt the cylinder at 45° to drain the water for 1 minute, and then measure the mass (g) of the cylinder.

[0152] (6) Subtract the mass of the cylinder before water absorption from the mass of the cylinder measured in (3) above from the mass of the cylinder after water absorption measured in (5) above, and calculate the water absorption amount (g) of the sample. Then divide the water absorption amount by the mass of the sample (=0.16g) to obtain the water absorption amount per unit mass of the sample (polymer absorbent) (g / g).

[0153] It should be noted that the water absorption (g / g) when the specified time (i.e., water absorption time) in (5) above is 5 seconds is "the water absorption amount when 40g / cm is applied". 2 The initial water absorption after 5 seconds of load is defined as "the water absorption (g / g) after 20 seconds or more".

[0154] Furthermore, in this invention, it is preferable that the composite absorbent contains, in addition to the aforementioned polymeric absorbent, a conventional superabsorbent polymer (SAP). If the composite absorbent contains both a polymeric absorbent and SAP, then urine and other bodily fluids are rapidly absorbed through the polymeric absorbent within the composite absorbent, temporarily retained, and then transported to the SAP, which has a high water retention capacity, where they can be retained. Therefore, as an absorbent, it can exhibit higher absorption performance.

[0155] Furthermore, when the composite absorbent contains this polymeric absorbent and SAP, the amount of liquid transferred from the polymeric absorbent to the SAP is preferably 5.0 g / g or more. If the amount of liquid transferred from the polymeric absorbent to the SAP is 5.0 g / g or more, the body fluid temporarily held by the polymeric absorbent can be more effectively delivered to the SAP, thus allowing the absorbent to achieve even higher absorption efficiency. It should be noted that the amount of liquid transferred from the polymeric absorbent to the SAP is more preferably 23.0 g / g or more, more preferably 27.0 g / g or more, and particularly preferably 33.0 g / g or more.

[0156] The amount of liquid transferred from the polymer absorbent to the SAP can be determined as follows.

[0157] <Method for determining the amount of liquid transferred from polymeric absorbent to SAP>

[0158] (1) Add 0.3g of the test sample (polymer absorbent) to a plastic cylinder (inner diameter: 60mm, outer diameter: 70mm, height: 52mm, mass: 64g) to which a nylon mesh material (manufactured by NBC Meshtec Inc., N-NO255HD 115 (standard width: 115cm, 255 meshes / 2.54cm, opening: 57μm, wire diameter: 43μm, thickness: 75μm)) is adhered to the bottom surface. Evenly level the cylinder and measure its mass (g). It should be noted that this test method is performed at a temperature of 25°C and a humidity of 60%. Alternatively, if the test sample (polymer absorbent) is recycled from a sanitary product, it can be obtained according to the aforementioned <Recycling Method for the Test Sample (Polymer Absorbent)>.

[0159] (2) Place a plastic cylinder (inner diameter: 60mm, outer diameter: 70mm, height: 52mm, mass: 64g) in a petri dish (inner diameter: 85mm, depth: 20mm), sprinkle 0.3g of superabsorbent polymer (SAP) evenly into the cylinder, remove the cylinder, and measure the mass (g) of the petri dish.

[0160] (3) Add 60 mL of physiological saline (0.9% sodium chloride aqueous solution) to a petri dish with a base (inner diameter: 85 mm, depth: 20 mm, base configuration: two bases are arranged in parallel at a 24 mm interval in the center of the bottom (inner surface side), base width: 2 mm, base height: 2 mm, base length: 25 mm).

[0161] (4) Place the cylinder containing the test sample (polymer absorbent) on the base of the petri dish with a base in the center, immerse the bottom of the cylinder in physiological saline, and let the sample in the cylinder absorb the physiological saline for 3 minutes.

[0162] (5) After absorbing water for 3 minutes, lift the cylinder, tilt the cylinder at 45° to drain water for 1 minute, and then measure the mass (g) of the cylinder.

[0163] (6) Subtract the mass (g) of the cylinder before water absorption determined in (1) above from the mass (g) of the cylinder after water absorption determined in (5) above, and calculate the water absorption amount (g) of the sample. Then divide the water absorption amount by the mass of the sample (=0.3g) to obtain the water absorption amount per unit mass of the sample (g / g).

[0164] (7) Next, place the cylinder after water control in (5) above on the petri dish containing SAP, so that the sample in the cylinder and the SAP in the petri dish come into contact through the bottom surface (mesh material) of the cylinder.

[0165] (8) After the sample has been in contact with SAP for 3 minutes, remove the cylinder and measure the mass (g) of the culture dish.

[0166] (9) Subtract the mass of the petri dish measured in (8) from the mass of the petri dish measured in (2) above, and calculate the water absorption of SAP (g). Then divide the water absorption by the mass of the sample (=0.3g) to obtain the water absorption of SAP per unit mass of the sample (g / g), that is, the amount of liquid transferred to SAP per unit mass of the sample (g / g).

[0167] Furthermore, when the composite absorbent contains a polymeric absorbent and SAP as described above, the polymeric absorbent preferably has a liquid discharge rate of 70% or higher for the absorbed water. If the liquid discharge rate of the polymeric absorbent is 70% or higher, the polymeric absorbent readily releases the absorbed water, thus making it easier to transport the body fluid temporarily held by the polymeric absorbent to the SAP. It should be noted that the liquid discharge rate of the polymeric absorbent is particularly preferably 75% or higher.

[0168] The liquid discharge rate of this polymeric absorbent can be determined as follows.

[0169] <Method for Determining the Liquid Discharge Rate of Polymer Absorbents>

[0170] (1) Seal 1g of the test sample (polymer absorbent) into a mesh bag cut into 10cm squares (manufactured by NBCMeshtec Inc., N-NO255HD 115 (standard width: 115cm, 255 meshes / 2.54cm, opening: 57μm, wire diameter: 43μm, thickness: 75μm)). It should be noted that the mass (g) of the mesh bag is measured beforehand. Furthermore, this test method is performed at a temperature of 25°C and a humidity of 60%. If the test sample (polymer absorbent) is recycled from a sanitary product, it can be obtained according to the aforementioned <Recycling Method for Test Sample (Polymer Absorbent)>.

[0171] (2) Immerse the mesh bag containing the sample in physiological saline (0.9% sodium chloride aqueous solution) for 1 hour.

[0172] (3) Determine the mass (g) of the mesh bag after it has been suspended for 5 minutes to drain water.

[0173] (4) Subtract the mass of the sample (=1g) and the total mass of the mesh bag from the mass of the mesh bag after water control determined in (3) above, and calculate the water absorption (g) of the sample. Then divide the water absorption by the mass of the sample (=1g) to obtain the water absorption per unit mass of the sample (polymer absorbent) (g / g).

[0174] (5) Then, the mesh bag after water control in (3) above was centrifuged at 150g for 90 seconds, and the mass (g) of the mesh bag after centrifugation was measured.

[0175] (6) Subtract the mass (g) obtained by subtracting the mass of the sample (=1g) and the total mass of the mesh bag after centrifugation from the water absorption of the sample determined in (4) above, and the mass (g) obtained by subtracting the mass of the sample (=1g) and the total mass of the mesh bag determined in (5) above. Calculate the liquid discharge amount (g) of the sample from this mass. Then divide the liquid discharge amount by the mass of the sample (=1g) to obtain the liquid discharge amount per unit mass of the sample (polymer absorbent) (g / g).

[0176] (7) Divide the liquid discharge per unit mass obtained in (6) above by the water absorption per unit mass obtained in (4) above and multiply by 100 to obtain the liquid discharge of the sample (polymer absorbent) relative to the water absorption, i.e., the liquid discharge rate (%).

[0177] The manufacturing method of this polymeric absorbent will be described in detail below, using absorbent A as an example.

[0178] [Manufacturing method of polymeric absorbent]

[0179] The above-mentioned absorbent A can be as follows:Figure 2 As shown, it is obtained through a cross-linking polymerization process and a hydrolysis process. These processes are explained below.

[0180] (Cross-linking polymerization process)

[0181] First, oil-soluble monomers for crosslinking polymerization, crosslinking monomers, surfactants, water, and a polymerization initiator as needed are mixed to obtain a water-in-oil droplet emulsion. This water-in-oil droplet emulsion is an emulsion in which the oil phase forms a continuous phase and water droplets are dispersed therein.

[0182] Next, regarding the absorbent A mentioned above, such as Figure 2 As shown in the figure above, butyl methacrylate, an oil-soluble monomer, is used as a (meth)acrylate; divinylbenzene is used as a crosslinking monomer; sorbitol monooleate is used as a surfactant; and isobutyronitrile is used as a polymerization initiator to carry out crosslinking polymerization to obtain the monolithic column A.

[0183] Specifically, for absorbent A, such as Figure 2 As shown in the figure above, first mix 9.2g of tert-butyl methacrylate as an oil-soluble monomer, 0.28g of divinylbenzene as a crosslinking monomer, 1.0g of sorbitan monooleate (hereinafter referred to as "SMO") as a surfactant, and 0.4g of 2,2'-azobis(isobutyronitrile) as a polymerization initiator and dissolve them evenly.

[0184] Next, the mixture of tert-butyl methacrylate / divinylbenzene / SMO / 2,2'-azobis(isobutyronitrile) was added to 180g of pure water and stirred under reduced pressure using a vacuum stirring degassing mixer (manufactured by EME, Inc.) as a planetary stirring device to obtain a water-in-oil droplet emulsion.

[0185] The emulsion was then rapidly transferred to a reaction vessel and sealed, and polymerized at 60°C for 24 hours. After polymerization, the contents were removed, extracted with methanol, and dried under reduced pressure to obtain a monolithic column A with a continuous macroporous structure. It should be noted that SEM observation of the internal structure of monolithic column A showed that it possesses a continuous bubble structure with a continuous framework thickness of 5.4 μm. Furthermore, mercury porosimetry determined the average diameter of the continuous pores to be 36.2 μm and the total micropore volume to be 15.5 mL / g.

[0186] It should be noted that the content of divinylbenzene relative to all monomers is preferably 0.3 to 10 mol%, more preferably 0.3 to 5 mol%. Furthermore, the ratio of divinylbenzene to the total of butyl methacrylate and divinylbenzene is preferably 0.1 to 10 mol%, more preferably 0.3 to 8 mol%. It should be noted that in the above-mentioned absorbent A, the ratio of butyl methacrylate to the total of butyl methacrylate and divinylbenzene is 97.0 mol%, and the ratio of divinylbenzene is 3.0 mol%.

[0187] The amount of surfactant added can be set according to the type of oil-soluble monomer and the desired size of emulsion particles (macropores), and is preferably in the range of about 2% to 70% relative to the total amount of oil-soluble monomer and surfactant.

[0188] It should be noted that, in order to control the shape and size of the bubbles in column A, alcohols such as methanol and stearyl alcohol; carboxylic acids such as stearic acid; hydrocarbons such as octane, dodecane, and toluene; and cyclic ethers such as tetrahydrofuran and dioxane can coexist in the polymerization system.

[0189] Furthermore, there are no particular restrictions on the mixing method when forming water-in-oil droplet emulsions. For example, any mixing method can be used, such as mixing all components together at once, or dissolving the oil-soluble components (which are oil-soluble monomers, surfactants, and oil-soluble polymerization initiators) and the water-soluble components (which are water-soluble polymerization initiators) uniformly separately and then mixing the components.

[0190] Furthermore, there are no particular limitations on the mixing device used to form the emulsion. Any device such as a conventional mixer, homogenizer, or high-pressure homogenizer can be used depending on the desired emulsion particle size. Alternatively, a so-called planetary mixing device can be used, in which the material to be treated is added to a mixing container, and the mixing container rotates on its own axis while being tilted, thereby stirring and mixing the material to be treated.

[0191] Furthermore, there are no particular restrictions on mixing conditions; the stirring speed and stirring time can be set arbitrarily according to the desired emulsion particle size. It should be noted that when using the aforementioned planetary stirring device, water droplets in the W / O emulsion can be generated uniformly, and their average diameter can be set arbitrarily within a wide range.

[0192] The polymerization conditions for water-in-oil droplet emulsions can vary depending on the type of monomer and initiator. For example, when using azobisisobutyronitrile, benzoyl peroxide, or potassium persulfate as polymerization initiators, polymerization can be carried out in a sealed container under an inert atmosphere at a temperature of 30–100°C for 1–48 hours. When using hydrogen peroxide-ferrous chloride or sodium persulfate-sodium acid sulfite as polymerization initiators, polymerization can be carried out in a sealed container under an inert atmosphere at a temperature of 0–30°C for 1–48 hours.

[0193] It should be noted that after polymerization, the contents are removed and subjected to Soxhlet extraction using solvents such as isopropanol. This removes unreacted monomers and residual surfactants, yielding the desired product. Figure 2 The overall column A is shown in the middle figure.

[0194] (Hydrolysis process)

[0195] Next, the process of hydrolyzing the monolithic column A (crosslinked polymer) to obtain absorbent A (hydrolysis process) will be described.

[0196] First, the monolithic column A is immersed in dichloroethane containing zinc bromide and stirred at 40°C for 24 hours. It is then hydrolyzed by sequential contact with methanol, 4% hydrochloric acid, 4% sodium hydroxide aqueous solution, and water, followed by drying to obtain a block-shaped absorbent A. Next, the block-shaped absorbent A is pulverized to a specified size (i.e., a particle size of 300 μm or larger) to obtain granular absorbent A. It should be noted that the granular form of absorbent A can be shaped (granulated) during or after drying.

[0197] Furthermore, there are no particular restrictions on the method of hydrolyzing the monolithic column A; various methods can be used. Examples include contacting strong bases such as sodium hydroxide with aromatic solvents such as toluene and xylene, halogen solvents such as chloroform and dichloroethane, ether solvents such as tetrahydrofuran and isopropyl ether, amide solvents such as dimethylformamide and dimethylacetamide, alcohol solvents such as methanol and ethanol, carboxylic acid solvents such as acetic acid and propionic acid, or water; or contacting hydrohalic acids such as hydrochloric acid, sulfuric acid, nitric acid, trifluoroacetic acid, methanesulfonic acid, and p-toluenesulfonic acid, or Lewis acids such as zinc bromide, aluminum chloride, aluminum bromide, titanium chloride (IV), cerium chloride / sodium iodide, and magnesium iodide.

[0198] In addition, among the polymer raw materials of the organic polymer that forms the hydrophilic continuous skeleton of absorbent A, there are no particular limitations on (meth)acrylates, but C1 to C10 (i.e., carbon number 1 to 10) alkyl esters of (meth)acrylates are preferred, and C4 (i.e., carbon number 4) alkyl esters of (meth)acrylates are particularly preferred.

[0199] It should be noted that, as C4 alkyl esters of (meth)acrylic acid, examples include tert-butyl (meth)acrylic acid, n-butyl (meth)acrylic acid, and isobutyl (meth)acrylic acid.

[0200] In addition, the monomers used in crosslinking polymerization can be only (meth)acrylate and divinylbenzene, or they can contain other monomers besides (meth)acrylate and divinylbenzene.

[0201] In the latter case, other monomers are not particularly limited, and examples include styrene, α-methylstyrene, vinyltoluene, vinyl benzyl chloride, glycidyl methacrylate, 2-ethylhexyl methacrylate, isobutylene, butadiene, isoprene, chloroprene, vinyl chloride, vinyl bromide, vinylidene chloride, tetrafluoroethylene, methacrylonitrile, vinyl acetate, ethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, etc.

[0202] It should be noted that the ratio of monomers other than (meth)acrylate and divinylbenzene in the total monomers used in the crosslinking polymerization is preferably 0 to 80 mol%, more preferably 0 to 50 mol%.

[0203] Furthermore, the surfactant is not limited to the aforementioned sorbitol monooleate; any surfactant that can form a water-in-oil (W / O) emulsion when the monomer for crosslinking polymerization is mixed with water is acceptable. Examples of such surfactants include nonionic surfactants such as sorbitol monolaurate, sorbitol monopalmitate, sorbitol monostearate, sorbitol trioleate, polyoxyethylene nonylphenyl ether, polyoxyethylene stearyl ether, and polyoxyethylene sorbitol monooleate; anionic surfactants such as potassium oleate, sodium dodecylbenzenesulfonate, and sodium dioctyl sulfosuccinate; cationic surfactants such as distearate dimethyl ammonium chloride; and amphoteric surfactants such as lauryl dimethyl betaine. These surfactants can be used alone or in combination of two or more.

[0204] Furthermore, polymerization initiators are suitably compounds that generate free radicals through heat and light irradiation. Moreover, polymerization initiators can be water-soluble or oil-soluble, and examples include azobis(4-methoxy-2,4-dimethylpentanonitrile), azobisisobutyronitrile, azobisdimethylpentanonitrile, azobiscyclohexanenitrile, azobiscyclohexaneformitrile, azobis(2-methylpropanediamine) dihydrochloride, benzoyl peroxide, potassium persulfate, ammonium persulfate, hydrogen peroxide-ferrous chloride, sodium persulfate-sodium acid sulfite, tetramethylthiuram disulfide, etc. However, depending on the need, there are also systems where polymerization occurs even without the addition of a polymerization initiator, only through heating and light irradiation; therefore, when using such systems, it is not necessary to add a polymerization initiator.

[0205] It should be noted that, in addition to the light incontinence pad described in the above embodiments, the composite absorbent of the present invention can also be applied to various hygiene products such as shorts-type disposable diapers, band-type disposable diapers, sanitary napkins, absorbent linings, absorbent pads (e.g., pressure ulcer pads, maternity pads, etc.), absorbent sheets, breast pads, disposable diapers for pets, absorbent pads for pets, pet waste disposal sheets, wet wipes, wet wipes, cosmetic wipes, and masks. Therefore, the bodily fluids that the composite absorbent is intended to absorb are liquids excreted by the wearer of the hygiene products, such as urine, sweat, feces, menstrual blood, vaginal discharge, breast milk, blood, and exudate.

[0206] Furthermore, the present invention is not limited to the above-described embodiments, and can be appropriately combined, substituted, or modified without departing from the purpose and spirit of the present invention.

[0207] Explanation of reference numerals in the attached figures

[0208] 1. Light incontinence pad

[0209] 2 Surface sheet

[0210] 3. Back panel

[0211] 4. Complex Absorber

Claims

1. A composite absorber, characterized in that, It is a composite absorbent used in hygiene products to absorb bodily fluids. The composite absorber comprises: a particulate polymeric absorbent with a hydrophilic continuous framework and continuous pores. The polymeric absorbent is a hydrolysate of a cross-linked polymer of (meth)acrylate and divinylbenzene, a compound containing two or more vinyl groups per molecule, forming the hydrophilic continuous backbone of the organic polymer. The ratio of the cross-linked polymeric residues of the divinylbenzene in the organic polymer is 0.1 to 20 mol% relative to all structural units. The polymer absorbent has a particle size of 300 μm or more, a water absorption capacity of 54.5 g / g or more, and a liquid discharge rate of 70% or more.

2. The composite absorber according to claim 1, characterized in that, The volume increase rate of the polymer absorbent during saturation absorption relative to its initial volume is 233% to 567%.

3. The composite absorber according to claim 1 or 2, characterized in that, The porosity per unit volume of the polymer absorbent is above 85%.

4. The composite absorber according to claim 1 or 2, characterized in that, The average diameter of the continuous pores is 1 μm to 1000 μm.

5. The composite absorber according to claim 1 or 2, characterized in that, The polymeric absorbent is a monolithic columnar absorbent.

6. The composite absorber according to claim 1 or 2, characterized in that, The polymeric absorbent contains at least one -COONa group.

7. A hygiene product, characterized in that, It has the composite absorber as described in any one of claims 1 to 6.

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