JP2019118593A - Absorbent article - Google Patents

Abstract

To provide an absorbent article excellent in wearing feeling even when absorbing a discharged fluid such as urine, being thin, and comprising preferable fitting property.SOLUTION: There is provided an absorbent article comprising: a surface sheet 2 forming a skin facing surface; a rear surface sheet 3 forming a non-skin facing surface; and an absorber 4 arranged between both sheets 2, 3. The absorber 4 comprises a base material sheet 20 and an absorbent core 14 formed on one surface of the base material sheet 20. The absorbent core 14 comprises a water absorptive resin 43 and a water soluble polymer 47 for fixing the water absorptive resin 43 to the base material sheet 20. The water absorptive resin 43 includes a low crosslinking resin 45 having a non-crosslinking part on which there is no crosslink, on a surface, has water absorption speed (JIS K 7224(1996)) which is 25 seconds or less, and has volume increase ratio in artificial urine absorption time measured by a prescribed method which is 16.5 times or less.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an absorbent article.

  As absorbents used for absorbent articles such as disposable diapers and incontinence pads, absorbents containing pulp fibers and a water-absorbent resin are known, but absorbents containing pulp fibers are bulky and large in thickness. For some reasons, thinning of the absorber has been proposed. For example, Patent Document 1 discloses a base material layer, an absorbent polymer particle supported by the base material layer, a thermoplastic adhesive material for fixing the absorbent polymer particles to the base material layer, an absorbent polymer particle, and a heat An absorbent structure is described which comprises an oil scavenger component in contact with a plastic adhesive material.

  In addition, the applicant has found that a water-absorbent resin having a centrifugal retention amount of 20 g / g or less in accordance with JIS K 7223 is sandwiched between two sheets containing bulky cellulose fibers, and a water-soluble binder is interposed between the sheets. The absorbent body which is fixed to the sheet, which has redness a * value of 0 or less of red part stained red by blood after being injected and washed with water according to a predetermined procedure The napkin is proposed (patent document 2).

Patent No. 5784829 gazette Patent No. 5508747 gazette

The absorbent structure described in Patent Document 1 is increased in thickness by the fact that the absorptive capacity of the absorbent polymer is lowered by the thermoplastic adhesive material, and the absorbent polymer that has absorbed the excrement fluid such as urine expands. Wearing feeling sometimes deteriorated.
Although the sanitary napkin described in Patent Document 2 is thin because the absorber does not contain pulp fibers, there is room for improvement in the sense of wearing after absorbing an excretory fluid such as urine.

  Therefore, an object of the present invention is to provide an absorbent article which can eliminate the drawbacks of the above-mentioned prior art.

  The present invention is an absorbent article comprising a top sheet forming a skin-facing surface, a back sheet forming a non-skin-facing surface, and an absorbent interposed between the two sheets, the absorbent comprising Material sheet and an absorbent core formed on one side of the substrate sheet, the absorbent core does not contain pulp fibers, and a water absorbent resin and the water absorbent resin are fixed to the substrate sheet Containing a water-soluble polymer, and the water-absorbent resin contains a low-crosslinked resin having a non-crosslinked portion on the surface, and has a water absorption rate [JIS K 7224 (1996)] of 25 seconds or less, which will be described later. An absorbent article is provided, wherein the volume increase rate at the time of artificial urine absorption measured by a predetermined method is 16.5 times or less.

  The absorbent article of the present invention is thin and has a good fit, and is excellent in wearing feeling even when it absorbs excrement fluid such as urine.

FIG. 1 is a plan view of an incontinence pad which is an embodiment of the absorbent article of the present invention. FIG. 2 is a cross-sectional view schematically showing a cross section taken along line I-I of FIG. FIG. 3 is a cross-sectional view of the incontinence pad absorber shown in FIG. FIG. 4 is a cross-sectional view of the absorber shown in FIG. 3 after absorbing waste fluid such as urine. FIG. 5 is a perspective view showing an apparatus for manufacturing the absorber shown in FIG. 6 (a) and 6 (b) are perspective views showing an apparatus having a different structure from the coating head shown in FIG.

  Hereinafter, the absorbent article of the present invention will be described based on the incontinence pad 1 which is a preferred embodiment thereof with reference to the drawings. The top view which looked at the incontinence pad 1 of this embodiment from the surface sheet 2 side is shown by FIG. 1, and sectional drawing of the incontinence pad 1 of this embodiment is shown by FIG. The incontinence pad 1 of the present embodiment, as shown in FIG. 2, includes a liquid-permeable top sheet 2 forming a skin-facing surface, a back sheet 3 forming a non-skin-facing surface, and a sheet 2 and 3 between them. An interposed absorbent 4 is provided.

  The incontinence pad 1 is, as shown in FIG. 1, an excretory part opposing part B disposed opposite to the excretory part (vagina etc.) of the wearer at the time of wearing, and the belly side of the wearer than the excretory part opposing part B A front portion A is disposed closer to the front side, and a rear portion C is disposed closer to the back side (rear side) of the wearer than the discharge portion facing portion B. The incontinence pad 1 has a longitudinal direction X corresponding to the longitudinal direction of the wearer and a lateral direction Y orthogonal to the longitudinal direction X, and in the longitudinal direction X, the anterior portion A, the excretory portion opposed portion B and the posterior portion C It is divided in order. The longitudinal direction X corresponding to the front-rear direction of the wearer is a direction from the ventral side of the wearer to the dorsal side through the crotch when worn. Further, the incontinence pad 1 is formed symmetrically with respect to a center line CL extending in the longitudinal direction X. The longitudinal direction X is also a direction parallel to the center line CL.

  Further, in the present specification, the skin facing surface is a surface of the incontinence pad 1 or a component thereof (for example, the absorber 4) that is directed to the skin side of the wearer when wearing the incontinence pad 1, and the non-skin facing surface is The incontinence pad 1 or a component thereof is a surface directed to the opposite side (clothing side) from the skin side when the incontinence pad 1 is worn.

  Further, in the absorbent article of the present invention, the excretory part facing part B is an individualized form in which the absorbent article is folded in three in the absorbent article having no wing like the incontinence pad 1 of the present embodiment. The longitudinal direction of the absorbent article, with respect to the two folds (not shown) crossing the absorbent article in the lateral direction (the lateral direction of the absorbent article, the Y direction in the figure), which occurs when folded. It means the area enclosed by the first fold and the second fold counting from the front end of X. In the absorbent article having a wing portion, the excretory part facing portion B is a region (one wing portion) having the wing portion in the longitudinal direction of the absorbent article (longitudinal direction of the absorbent article, X direction in the figure). It means a region between the base along the longitudinal direction X and the base along the longitudinal direction X of the other wing portion).

  In the incontinence pad 1, the surface sheet 2 covers the whole area of the skin-facing surface of the absorbent body 4 as shown in FIGS. 1 and 2, and the outer side of the absorbent body 4 from the side edges along the longitudinal direction X It is extending to the side. On the other hand, the back sheet 3 covers the whole area of the non-skin facing surface of the absorbent body 4 and further extends outward from both side edges along the longitudinal direction X of the absorbent body 4 in the lateral direction Y. And the side flap portion S is formed. On the non-skin opposing surface on the back sheet 3 side of the incontinence pad 1, an adhesive portion 31 for fixing to underwear such as shorts is provided. The back sheet 3 and the side sheet 5 are bonded to each other at the extension from the side edges along the longitudinal direction X of the absorber 4 by a known bonding means such as an adhesive, heat seal, ultrasonic seal or the like. The top sheet 2 and the back sheet 3 may be bonded to each other by an adhesive, respectively.

  As a forming material of the back surface sheet 3, various materials conventionally used for the back surface sheet of an absorptive article etc. can be used without particular restriction, for example, a liquid impermeable or water repellent resin film, a resin film, A laminate sheet with a non-woven fabric can be used.

  In the incontinence pad 1, as shown in FIGS. 1 and 2, a pair of side sheets 5 is disposed on both sides of the skin facing surface along the longitudinal direction X. Preferably, the side sheets 5 are disposed over the entire length in the longitudinal direction X of the incontinence pad 1 so as to overlap the left and right sides along the longitudinal direction X of the absorber 4 in plan view. The side sheet 5 extends outward in the lateral direction Y more than the absorber 4, and the extension portion thereof and the extension portion in the lateral direction Y of the back sheet 3 are joined to form a side flap portion S. doing.

  At the inner edge of the side sheet 5 in the transverse direction Y, one or more thread-like elastic members 16 are fixed in an extended state along the longitudinal direction X, and the incontinence pad is contracted by the contraction of the elastic members 16. A pair of leak-barrier cuffs 15 extending in the longitudinal direction X is formed on both sides in the longitudinal direction X of 1. More specifically, the leak-barrier cuff 15 has a fixed end 15b extending in the longitudinal direction X, a free end 15a, and a folded portion 15c folded outward between the free end 15a and the fixed end 15b. (See Figure 2). The above-mentioned elastic member 16 is fixed to the free end 15a side, and when the elastic member 16 contracts, the free end 15a and the fixed end 15b, that is, the folded back portion 15c, is on the wearer's body side. Stand up towards you. The leak-barrier cuff 15 has a fixing portion 5a fixed to the top sheet 2 by bonding means such as an adhesive in the vicinity of each side edge along the longitudinal direction of the absorber 4, and the transverse direction Y of the fixing portion 5a The inner end is a fixed end 15 b of the leak-barrier cuff 15. The leakage preventing cuff 15 prevents lateral leakage of waste fluid such as urine by standing up during wearing between the fixed end 15 b and the free end 15 a.

  As the side sheet 5, various sheets conventionally used in the relevant technical field can be used without particular limitation, and for example, a liquid impermeable or water repellent non-woven fabric or resin film, or a laminate of a resin film and non-woven fabric Etc. can be used.

  In the incontinence pad 1, the top sheet 2 and the back sheet 3 extend outward in the longitudinal direction X from the front end and the rear end of the absorbent body 4 in the longitudinal direction X, respectively, Are joined together by known joining means such as ultrasonic sealing. Specifically, as shown in FIG. 1, the top sheet 2 and the back sheet 3 are joined by a joint (not shown) formed in the extension on the front end side and the rear end side in the longitudinal direction X. .

  As shown in FIG. 2, the absorbent body 4 includes a base sheet 20 and an absorbent core 14 formed on one side 20 a of the base sheet 20. The absorber 4 in the present embodiment has a substantially rectangular shape having convex portions protruding outward in the longitudinal direction X at both ends in the longitudinal direction X in plan view as shown in FIG. It extends from A to the rear portion C via the excretion portion facing portion B. FIG. 3 shows a cross-sectional view of the absorber 4 shown in FIG. 2, and FIG. 4 shows a cross-sectional view of the absorber 4 after absorbing excretory fluid such as urine. Although FIG. 2 shows a configuration in which one side 20a of the base sheet 20 faces the non-skin facing side, FIG. 3 and FIG. 4 show the base sheet 20 facing downward in the figure. It shows.

  The base sheet 20 is made of a material capable of holding the absorbent core 14, and may be a liquid-permeable sheet or a liquid-impermeable sheet or a liquid-impermeable sheet. The base sheet 20 can be made of, for example, non-woven fabric, paper, woven fabric, and film. You may use the laminated body of these 2 or more types of materials as a base material sheet. From the viewpoint of diffusing excretory fluid such as urine in the planar direction, the substrate sheet is preferably made of a liquid-permeable fiber sheet.

  As the non-woven fabric, those obtained by various manufacturing methods can be used without particular limitation. Examples of nonwoven fabrics include spunlace nonwoven fabrics, spunbond nonwoven fabrics, air-through nonwoven fabrics, meltblown nonwoven fabrics, needle-punched nonwoven fabrics and resin-bonded nonwoven fabrics. These non-woven fabrics can be used alone or in the form of a laminate of two or more non-woven fabrics.

  As the woven fabric, one having various fiber systems can be used. As paper, the paper-made fiber can be used as a raw material, and what was obtained by the wet papermaking method or the dry papermaking method can be used. As the film, for example, one obtained by being formed by T-die method or inflation method and uniaxially or biaxially stretched can be used.

  As the various materials constituting the base sheet 20, for example, synthetic polymer materials such as various thermoplastic resins, and natural polymer materials such as cellulose such as pulp can be used. Examples of the thermoplastic resin include polyolefin fibers such as polyethylene (PE) and polypropylene (PP), polyester fibers such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), and polyacrylics such as polyacrylic acid and polymethacrylic acid ester. Acid based fibers, vinyl based fibers such as polystyrene and polyvinyl chloride can be used. These resins may be used alone or in combination of two or more. When fibers are formed from these resins, fibers of a single resin may be formed, or core-sheath type or side-by-side type composite fibers may be formed.

The base sheet 20 preferably has a basis weight of 10 g / m ² or more, more preferably 15 g / m ² or more, and more preferably 20 g / m ² or more from the viewpoint of shape retention of the absorber 4. It is more preferable that The base sheet 20 is preferably 70 g / m ² or less, more preferably 65 g / m ² or less, and more preferably 60 g / m ² or less from the viewpoint of thinness and flexibility of the absorber 4. Is more preferred. Specifically, the base sheet preferably has a basis weight of 10 g / m ² or more and 70 g / m ² or less, more preferably 15 g / m ² or more and 65 g / m ² or less, and 20 g / m 2 it is more preferably ² or more 60 g / ^{m 2} or less.

  An absorbent core 14 is formed on one side 20 a of the base sheet 20. The absorbent core 14 may be located on the substrate sheet 20 in direct contact with the substrate sheet 20, or one or more between the substrate sheet 20 and the absorbent core 14 The base sheet 20 and the absorbent core 14 may be indirectly adjacent to each other in the state where the members and layers are interposed, but from the viewpoint of thinning the absorbent article, the base sheet 20 and the absorbent core It is preferable not to intervene another member between them and 14.

The absorbent core 14 of the present embodiment does not contain pulp fibers, and contains a water-absorbent resin 43 and a water-soluble polymer 47 that fixes the water-absorbent resin 43 to the base sheet 20. The “water solubility” of the water-soluble polymer 47 is that the solubility in 100 g of water at 25 ° C. is 0.5 g or more, preferably 1 g or more, more preferably 5 g or more, and still more preferably 10 g or more.
A predetermined amount of the evaluation target (water-soluble polymer) and 50 mL of ion-exchanged water at a liquid temperature of 25 ° C. are charged into a 100 mL glass beaker (5 mm)) and mixed, and the mixture is lengthed 20 mm in the long axis direction A stirrer chip with a length (width) of 7 mm in the minor axis direction is introduced, and the mixture is stirred at a rotational speed of 600 rpm using a magnetic stirrer (for example, HPS-100 manufactured by As One Co., Ltd.). Check if it dissolves in 50 mL of ion exchange water within 24 hours from the start. Such a series of operations is performed on a plurality of samples having different total weights of the evaluation object (the input to the beaker), and among the plurality of samples in which the entire amount of the evaluation object is dissolved, the dissolved amount is the largest. The value twice as much as the total weight of the evaluation object in the sample is taken as the solubility of the evaluation object in 100 g of water at 25 ° C. Thus, the water-soluble polymer 47 according to the present invention dissolves by contact with water.

  Examples of the water-soluble polymer 47 include polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl butyral, dextrin, polyethylene oxide, water-soluble nylon and the like, and among these, one or more selected from polyvinyl pyrrolidone, polyvinyl butyral and dextrin is preferable. The water-soluble polymer 47 can be used singly or in combination of two or more. Further, among the water-soluble polymers, polyvinyl pyrrolidone, in particular K-15, K-30, K-60 or K-90, among them, from the viewpoint of fixing of the water-soluble resin 43 to the base sheet 20, in particular It is preferred to use a grade of polyvinyl pyrrolidone.

The water absorbing resin 43 is made of a material which can be swelled by contact with water to absorb and hold water. The water absorbing resin 43 of the present embodiment includes the low crosslinking resin 45 having a non-crosslinked portion on the surface. The low crosslinked resin 45 is a resin having a non-crosslinked portion and a crosslinked portion on its surface (hereinafter also referred to as a first resin) and a resin having only the non-crosslinked portion on the surface (hereinafter also referred to as a second resin). And the like. The water absorbent resin 43 contained in the absorbent core 14 may be only the first resin or may be both the first resin and the second resin. The water absorbent resin 43 of the present embodiment contains a first resin and a second resin as the low cross-linking resin 45. When using a pulverized product of a water absorbent resin subjected to surface cross-linking treatment described later as the water absorbent resin 43 to be contained in the absorbent core 14 of the present invention, in addition to the first resin and the second resin It may contain a resin having no part (hereinafter, also referred to as a highly crosslinked resin). When manufacturing the absorbent core 14 including the hypercrosslinked resin 46, the water absorbing resin containing the hypercrosslinked resin when measuring the water absorption speed of the water absorbent resin 43 described later, the volume increase rate at the time of artificial urine absorption, etc. Measure the whole of 43 as a sample. That is, in the measurement related to the performance evaluation of the water absorbent resin 43, the measurement is performed by sampling from the entire water absorbent resin 43 used as a constituent material of the absorbent core 14.
Alternatively, only the low-crosslinked resin having a small particle diameter may be separated by classification or the like from the aggregate of the pulverized product by grinding, and only the low-crosslinked resin may be blended in the absorbent core 14. Even when the entire amount of the pulverized material is blended in the absorbent core 14, the aggregate of the pulverized material may be only the low-crosslinked resin, for example, by increasing the degree of the pulverization.
Further, when taking out the water absorbent resin 43 from the absorbent core 14, the absorbent core 14 may be dipped in ethanol. The water-soluble polymer 47 dissolves in ethanol, but the water-absorbent resin 43 does not dissolve in ethanol, so the water-absorbent resin 43 can be easily taken out.

  It is preferable that the water absorbing resin 43 be capable of absorbing and holding 20 times or more of its own weight of water. The water-absorbent resin 43 is preferably one capable of absorbing and retaining 20 times or more, particularly 30 times or more of its own weight if the object is urine, and 1 times or more, preferably 3 times or more if it is blood -It is preferable that it can be held. There is no particular limitation on the upper limit value of water absorption and retention in the water absorbent resin 43, but 1000 times its own weight can be used as a guideline for the upper limit.

  As the water absorbing resin 43, for example, various hydrogel materials, for example, cross-linked products of polymers or copolymers of acrylic acid or an alkali metal salt of acrylic acid, polyacrylic acid and salts thereof, and crosslinks of polyacrylate graft polymers , Crosslinked product of starch or carboxymethylated cellulose, crosslinked product of hydrolysis product of starch-acrylate graft copolymer, crosslinked product of vinyl alcohol-acrylate copolymer, maleic anhydride grafted polyvinyl alcohol A crosslinked product, a crosslinked isobutylene-maleic anhydride copolymer, a saponified product of a vinyl acetate-acrylic acid ester copolymer, and the like can be used.

As the water absorbing resin 43, any material can be used as long as the water absorption rate and the volume increase rate at the time of absorption of artificial urine are respectively described later, and it is preferable to use a pulverized material of the water absorbing resin subjected to surface cross-linking treatment. Is preferred. As the “water-absorbing resin subjected to surface crosslinking treatment”, an intermediate resin comprising a polymer or copolymer obtained by polymerizing a monomer in the presence or absence of a crosslinking agent is subjected to surface treatment as a post-treatment. It is preferable to use a crosslinked resin after application.
As a method for producing the intermediate resin, known polymerization methods can be used, and reverse phase suspension polymerization, for example, reverse phase suspension polymerization using an anionic surfactant described in Japanese Patent No. 2721658 as a dispersant And aqueous solution polymerization methods, for example, aqueous solution polymerization methods described in JP-A 2003-235889, and the like.
When surface crosslinking treatment is performed on the intermediate resin, the crosslinking agent used may be the same as or different from the crosslinking agent used for producing the intermediate resin.

The water absorbing resin 43 preferably has a water absorption rate of 25 seconds or less, more preferably 20 seconds or less, and still more preferably 15 seconds or less.
The water absorption rate is measured by the following method.

<Measurement method of water absorption rate>
The water absorption rate is measured by the vortex method [JIS K 7224 (1996)]. In a 100 mL glass beaker, 50 mL of physiological saline (0.9 mass% sodium chloride water) and a magnetic stirrer chip (central part diameter 8 mm, both end parts diameter 7 mm, length 30 mm, surface coated with fluorocarbon resin) The beaker is placed on a magnetic stirrer (HPS-100 manufactured by As One). The rotational speed of the magnetic stirrer is adjusted to 600 ± 60 rpm and the saline is stirred. 2.0 g of a water-absorbent resin, which is a measurement sample, is introduced into the solution at the center of the vortex of the saline solution under stirring, and the water absorption rate (seconds) of the water-absorbent resin according to JIS K 7224 (1996) taking measurement. Specifically, the stopwatch is started when the addition of the water-absorbent resin to the beaker is completed, and stopped when the stirrer tip is covered with the test solution (when the vortex disappears and the liquid surface becomes flat). Stop the watch and record the time (seconds) as the rate of water uptake by the vortex method. The measurement was performed at n = 5, the values at one upper and lower point were deleted, and the average value of the remaining three points was taken as the measured value. These measurements are performed at 23 ± 2 ° C. and 50 ± 5% humidity, and the samples are stored for 24 hours or more in the same environment before measurement.

  In the water-absorbent resin 43, the volume increase rate at the time of artificial urine absorption is 16.5 or less. The water-absorbent resin 43 preferably has a volume increase rate of 2 times or more, preferably 16.5 times or less, during artificial urine absorption. The volume increase rate at the time of artificial urine absorption in the present invention is measured by the following method.

<Method of measuring volume increase rate at artificial urine absorption>
A cylindrical plastic tube (inner diameter 30 mm, height 60 mm) provided with a wire mesh (aperture 63 μm, JIS Z8801-1: 2000) at the opening at the lower end was vertically stood and precisely weighed 1.0 g of a water-absorbent resin The water-absorbent resin is placed on a wire mesh so as to have a uniform thickness (stacking height). The deposition height H1 which is the height of the water absorbent resin deposited on the metal mesh is measured. A petri dish provided with a 0.9% by mass sodium chloride solution as artificial urine, and an artificial urine in an amount sufficient for the water-absorbent resin to swell, for example, an amount of 5 or more times the saturated absorption amount of the water-absorbent resin. Prepare. The cylindrical plastic tube is placed in the petri dish with the opening on the wire mesh side facing downward, and the water-absorbent resin is dipped in artificial urine for 30 minutes.
The cylindrical plastic tube is then removed from the petri dish.
Then, on the water absorbent resin that has become lumps due to absorption of artificial urine, a dividing cylinder with an outer diameter of 29.5 mm × thickness 22 mm and a mass of 150 g is placed on the water absorbent resin in the cylindrical plastic tube. Leave for 10 minutes with a load of 0 kPa applied. Next, the mass height H2 which is the height of the mass of the water absorbent resin is measured while the weight is mounted, and the measured mass height H2 is divided by the deposition height H1 to obtain a volume increase rate (H2 // Find H1).

  The low crosslinked resin 45 described above has a non-crosslinked portion, and therefore can not swell while retaining its original shape, and the shape collapses when a certain amount of excretory fluid such as urine is absorbed. At this time, the low-crosslinked resin 45 whose shape has collapsed is disposed so as to fill the voids between the other water-absorbent resins remaining in the original shape. Thereby, the water-absorbent resin 43 according to the present invention can suppress an increase in volume due to swelling, and can make the volume increase rate at the time of artificial urine absorption the above-mentioned range.

The incontinence pad 1 is thin compared to an incontinence pad comprising an absorbent core comprising pulp fibers. The incontinence pad 1 which is thin is easy to fit on the wearer's body, and the thickness L1 of the absorber 4 does not change significantly even if it absorbs excrement fluid such as urine, so that the fit property is maintained. Excellent feeling. Specifically, the absorbent core 14 does not contain pulp fibers, and contains a water-absorbent resin 43 and a water-soluble polymer 47 that fixes the water-absorbent resin 43 to the base sheet 20. When the absorbent core 14 absorbs the waste fluid, the water-soluble polymer 47 filling the space between the water-absorbent resins 43 dissolves in the absorbed part (see FIG. 4). When the water-soluble polymer 47 is dissolved, the water-absorbent resin 43 expands and tends to be large, that is, the water absorption by the water-absorbent resin 43 is less likely to be inhibited. As described above, since the absorption performance of the water-absorbent resin is easily exhibited, and the water absorption speed of the water-absorbent resin 43 is 25 seconds or less, it has excellent absorption performance.
In addition, since the water absorbent resin 43 in which the bond by the water soluble polymer 47 is broken can flow, the thickness L4 of the absorber 4 can be easily maintained uniform. This combined with the fact that the volume increase rate of the water absorbent resin 43 at the time of artificial urine absorption is 16.5 times or less, the thickness L4 of the absorber 4 does not easily increase even if it absorbs the waste fluid. As a result, since the incontinence pad 1 can maintain its thinness even after absorption of waste fluid, it can maintain excellent wearing feeling even after absorption of waste fluid. Further, since the water absorbent resin 43 can flow, it is possible to prevent the thickness L4 of the absorber 4 from locally increasing even if the incontinence pad 1 absorbs excretory fluid locally.

From the viewpoint of improving the absorption performance of the incontinence pad, the water-absorbent resin 43 preferably has a saturated absorption amount of 35 g / g or more, more preferably 40 g / g or more.
The saturated absorption is measured by the following method.

<Method of measuring saturated absorption amount>
The measurement of the saturated absorption amount is performed in accordance with JIS K 7223 (1996). A nylon woven fabric (mesh opening 250, Sanforce Mfg. Co., Ltd. name: nylon net, standard: 250 x mesh width x 30 m) is cut into a rectangle 10 cm wide and 40 cm long and folded in half at the longitudinal center, Both ends are heat sealed to make a nylon bag 10 cm wide (inner size 9 cm) and 20 cm long. Weigh precisely 1.00 g of a water-absorbent resin, which is a measurement sample, and place it uniformly in the bottom of the produced nylon bag. The nylon bag containing the sample is immersed in physiological saline (0.9 wt% sodium chloride water) for 1 hour. After one hour, the nylon bag is removed from the saline, suspended vertically for one hour and drained, and then the weight of the nylon bag is measured. The target saturated absorption is calculated from the following equation.
Saturated absorption of saline (g / g) = (abc) / c
In which a is the total weight (g) of the sample and nylon bag after water absorption, b is the weight (g) of the nylon bag before water absorption (during), c is the weight of the sample before water absorption (during) g). The measurement was performed five times (n = 5), the values at one upper and lower point were deleted, and the average value of the remaining three points was taken as the measured value.

  From the viewpoint of sufficiently enhancing the absorption performance of the absorbent core 14, the water absorbent resin 43 is preferably 70 mass% or more, more preferably 75 mass% or more, with respect to the total mass of the absorbent core 14. Is 85% by mass or less, more preferably 80% by mass or less, preferably 70% by mass or more and 85% by mass or less, more preferably 75% by mass or more and 80% by mass or less.

  From the viewpoint of making it difficult to inhibit the water absorption of the liquid of the water-absorbent resin, the water-soluble polymer 47 is preferably 0.1% or more, more preferably 0.3%, relative to the water-absorbent resin 43 in the absorbent core 14 The content is preferably 5% or less, more preferably 4% or less, and preferably 0.1% to 5%, more preferably 0.3% to 4%. The “ratio of the water-soluble polymer 47 to the water-absorbent resin 43” is a ratio calculated using the mass of the water-soluble polymer 47 as the numerator and the mass of the water-soluble polymer 47 as the numerator. It is

  From the viewpoint of making the volume increase rate at the time of artificial urine absorption of the water-absorbent resin 43 into a preferable range, it is preferable that the low crosslinked resin 45 has a non-crosslinked part and a crosslinked part on its surface. That is, it is preferable to contain the first resin as the low crosslinking resin 45.

  As the water absorbent resin 43, any material can be used as long as the water absorption rate and the volume increase rate at the time of artificial urine absorption are respectively mentioned above. The water absorption speed is realized by adjusting the median diameter and the like of the water absorbent resin. The volume increase rate upon absorption is realized by including the low crosslinking resin as described above. As the water absorbent resin 43 which contains the low cross-linking resin 45 and the water absorption rate and the volume increase rate at the time of artificial urine absorption are respectively in the above ranges, it is preferable to use a pulverized material of the water absorbent resin subjected to surface cross-linking treatment. . As the “water-absorbent resin subjected to surface cross-linking treatment” (hereinafter, also referred to as a raw material resin), the above-mentioned polymer or copolymer obtained by polymerizing a monomer in the presence or absence of a cross-linking agent It is preferable to use a cross-linked resin after surface treatment is applied to the intermediate resin of (1) as a post-treatment.

  The pulverized material of the raw material resin is obtained by pulverizing the raw material resin. For grinding of the raw material resin, for example, a mill or the like can be used. In the case of using a mill, the median diameter can be adjusted by variously changing the grinding conditions (hammer rotation number, repair portion screen hole diameter).

  The shape of the low-crosslinking resin 45 is not particularly limited, and may be spherical, massive, bowl-like or amorphous, or may be fibrous, but the low-crosslinking resin 45 is a ground product of the above-mentioned raw material resin It is preferable that it is indeterminate form.

From the viewpoint of making the water absorption rate of the water absorbing resin 43 into the above-mentioned range, the water absorbing resin 43 preferably has a particle diameter D ₅₀ at 50% cumulative volume measured by a laser diffraction particle size distribution method, that is, a median diameter of 150 μm. The thickness is more preferably 180 μm or more, preferably 500 μm or less, more preferably 400 μm or less, and preferably 150 μm to 500 μm, more preferably 180 μm to 400 μm.
The median diameter of the water-absorbent resin 43 can be measured using a laser diffraction / scattering type particle size distribution analyzer (LA-920, manufactured by Horiba, Ltd.) under the following measurement conditions.
Measurement method: Flow method Dispersion medium: Ethanol / distilled water = 90/10 wt%
Dispersion method: Stirring, built-in ultrasonic wave 3 minutes Sample concentration: 0.1%

The absorbent core 14 may contain other constituent materials other than the water absorbent resin 43 and the water-soluble polymer 47. For example, a deodorant, a fragrance, a plasticizer, a polyhydric alcohol and the like may be contained.
In addition to the above components, the absorbent core can also contain, if necessary, components capable of improving various performances of the absorbent core. Such components include, for example, thickeners, pH adjusters and the like.

  Some absorbent articles have an absorbent core covered with a core wrap sheet such as tissue paper or non-woven fabric, but from the viewpoint of making the absorbent article thinner, the absorbent body 4 is the base sheet 20. It is preferable that the surface on which the absorbent core 14 is formed is not covered by a separate sheet.

  In the incontinence pad 1, the absorber 4 is disposed in a state where the surface of the base sheet 20 on which the absorbent core 14 is disposed is directed to the non-skin facing surface side. According to such a configuration, the liquid is diffused quickly in the base sheet, and further, since a single sheet is disposed between the absorbent core and the surface material, liquid return hardly occurs. Thus, it is preferable that the base material sheet 20 side of the absorber 4 is directed to the surface sheet 2 side.

The thickness L1 (see FIG. 3) before absorption of the absorber 4 is preferably 2 mm or less, more preferably 1.7 mm or less, and further preferably from the viewpoint of achieving a better fit by thinning the incontinence pad more reliably Is 1.5 mm or less. The thickness before absorption of the absorber 4 is the maximum thickness before absorption of the absorber 4.
From the same viewpoint as above, the absorbent core 14 preferably has a thickness L3 (see FIG. 3) before absorption of 1.0 mm or less, more preferably 0.8 mm or less, and still more preferably 0.6 mm or less.

The thickness L1 of the absorber 4 and the thickness L3 of the absorbent core 14 are measured by the following method. That is, the absorber 4 to be measured is placed on a horizontal place without wrinkles or bending, and the thickness under a load of 5 cN / cm ² is measured. Specifically, for example, a thickness gauge (PEACOCK DIAL UPRIGHT GAUGES R5-C, manufactured by Ozaki Mfg. Co., Ltd.) is used to measure the thickness. At this time, a circular plate or a square plate in plan view (acrylic plate with a thickness of about 5 mm) whose size is adjusted so that the load is 5 cN / cm ² between the tip of the thickness gauge and the measurement object Place the to measure the thickness. The thickness L1 of the absorbent body 4 and the thickness L2 of the base sheet 20 are measured, and the difference between them is taken as the thickness L3 of the absorbent core 14.

The absorbent core 14 may be formed continuously on one side of the base sheet 20 without a gap, or may be formed such that a part of one side of the base sheet 20 is exposed. For example, when the base sheet 20 is rectangular, the absorbent core 14 can be formed only in the region between the left and right side regions. Alternatively, a plurality of absorbent cores 14 may be formed to extend linearly in one direction, and the surface of the base sheet 20 may be exposed in the region between adjacent absorbent cores 14. Furthermore, the absorbent core 14 may be arranged in a checkerboard pattern.
The absorbent core 14 may be formed on both sides of the base sheet 20, or may be formed on only one side of the base sheet 20.

  It is preferable that the thickness of an absorptive core is the value mentioned above even if the shape in planar view of an absorptive core is any of the above-mentioned cases.

  The ratio of the absorbent core 14 to the area of the absorber 4 is preferably 50 area% or more, more preferably 60 area% or more, and still more preferably 70, from the viewpoint of sufficiently enhancing the absorption capacity and diffusion of the absorber 4. Area% or more, 100 area% or less, preferably 95 area% or less, more preferably 90 area% or less, preferably 50 area% to 100 area%, more preferably 60 area% to 95 area % Or less, more preferably 70 area% or more and 90 area% or less. In addition, "the area of the absorber 4" and "the area of the absorptive core 14" are each area in the surface by which the absorptive core 14 was provided on the base material sheet 20. As shown in FIG. The ratio of the absorbent core 14 to the area of the absorbent body 4 being 100 area% means that the absorbent core 14 is disposed on the entire surface of the base sheet 20.

  Although the above description is for the case where the absorbent core is basically of a single layer, in the present invention, the absorbent core has the same composition or 2 different compositions. It may have a layered structure portion of layers or more. Even in such a case, it is preferable that the shape of the absorbent core 14 in plan view and the thickness of the absorbent core (thickness at the maximum thickness part) be as described above.

  The absorber according to the present invention is formed by applying a composition containing the water-absorbent resin 43 and the water-soluble polymer 47 on one side of the base sheet 20. Hereinafter, the composition containing the water-absorbent resin 43 and the water-soluble polymer 47 is also referred to simply as the composition 60. FIG. 5 shows an apparatus 50 suitable for the manufacturing method of applying the composition 60 to form the absorbent core 14 and manufacturing the absorbent 4. The apparatus 50 for manufacturing the absorber 4 shown in the figure includes a supply unit 51 of the composition 60, an application unit 53 of the composition 60, and a drying unit 55 of the composition 60.

  The supply unit 51 includes a storage tank 51 a of the composition 60. The composition 60 is stored in the tank 51a. The composition 60 in the tank 51a is stirred and homogenized by the stirring blade 51b. The stirring blade 51b is connected to a rotational drive source 51d such as a motor via a shaft 51c. One end of a conduit 52 is connected to the bottom of the tank 51a. The other end of the conduit 52 is connected to the application unit 53.

  The coating unit 53 includes a coating head 54 that coats the composition 60 on one side of the continuous body 20S of the elongated base sheet 20. Hereinafter, the continuous body 20S of the base material sheet 20 is also simply referred to as "continuous body 20S". The coating head 54 applies the composition 60 supplied from the storage tank 51 a through the pipe line 52 continuously in one direction D, that is, the transport direction D. As the coating head 54, one capable of applying a fluid such as the composition 60 is used. As an example of such a coating head 54, although a die coater etc. are mentioned, it is not restricted to this. In FIG. 5, the composition 60 is applied by the coating head 54 in the region between the side regions 20b and 20b in the longitudinal direction (direction D) of the continuous body 20S, and the wet applied body 63 is formed. The situation is shown.

  A drying unit 55 is disposed downstream of the application unit 53 in the conveyance direction D of the continuous body 20S. The drying unit 55 dries the coated body 63 formed by the coating unit 53 to remove volatile components, and fixes the absorbent core 14 which is a dried body of the coated body 63 to the continuous body 20S (base sheet 20). . The drying unit 55 is a device capable of removing volatile components from the wet coated body 63, and examples thereof include an infrared radiation device and a heated hot-air blowing device, but are not limited thereto. .

  By the above-described apparatus 50, a continuous body 4S of the absorbent body 4 in which the absorbent core 14 is formed on one side of the continuous body 20S, that is, one side of the base sheet 20 is obtained. The continuum 4S of the absorber 4 is subjected to post-processing as needed. As post-processing, for example, a step of cutting continuous body 4S of absorber 4 along its longitudinal direction and processing it into absorber 4 of each leaf, continuous body 4S of absorber 4 into a final product such as an absorbent article The process of incorporating and the process of winding up the continuous body 4S of the absorber 4 and making it original are mentioned.

  According to the above method, the target absorbent core 14 and the absorber 4 can be obtained by a simple process of applying the composition 60 to one side of the base sheet 20 and drying it. Moreover, according to the above method, the thickness and basis weight of the absorbent core 14 can be controlled with high accuracy. Thereby, local variation in the basis weight and thickness of the absorbent core 14 can be prevented from occurring easily, and the absorber 4 can exhibit stable absorption performance. In addition, the basis weight of the absorbent core can be optionally changed in a wide area on the base sheet 20. Furthermore, it is possible to form the absorbent core 14 extremely thinly by coating the composition 60 thinly.

  From the viewpoint of making the above effects more remarkable, the composition 60 is one in which the constituent material of the absorbent core 14 such as the water absorbent resin 43 or the water soluble polymer 47 described above is dispersed or dissolved in a solvent Is preferred. The composition 60 may contain water to such an extent that the water-absorbent resin 43 does not swell, but from the viewpoint of preventing the water-absorbent resin 43 from absorbing water and swelling, the composition 60 does not contain water. preferable. The absence of water is intended to exclude the purpose of intentionally adding a significant amount of water into the composition 60. Therefore, the presence of a trace amount of water unavoidably mixed as an impurity of a raw material and the like and a trace amount of water unavoidably mixed from the atmosphere is acceptable.

  The ratio of constituent materials such as the water-absorbent resin 43 and the water-soluble polymer 47 contained in the composition 60 is the same as that of the constituent materials such as the water-absorbent resin 43 and the water-soluble polymer 47 contained in the absorbent core 14 Adjust to the desired ratio. The composition 60 is also free of fiber materials such as pulp fibers.

  As a solvent contained in the composition 60, a non-aqueous solvent is suitably used. As such non-aqueous solvent, for example, ethanol, methanol, isopropyl alcohol, acetone, methyl ethyl ketone, butyl acetate and the like can be mentioned. These non-aqueous solvents can be used singly or in combination of two or more. Among these non-aqueous solvents, it is preferable to use ethanol in terms of availability, versatility, and safety. Ethanol is a volatile component and is removed in the drying unit as described above.

  The proportion of the non-aqueous solvent in the composition 60 is preferably 30% by mass or more, more preferably 35% by mass or more, and still more preferably 40% by mass or more, from the viewpoint of facilitating the coating of the composition 60. Also, it is preferably 70% by mass or less, more preferably 65% by mass or less, more preferably 60% by mass or less, and preferably 30% by mass to 70% by mass, more preferably 35% by mass to 65% by mass More preferably, it is 40% by mass or more and 60% by mass or less.

  The above-described apparatus 50 may have a structure in which the coating head 54 provided in the coating unit 53 forms the coating body 63 of a specific pattern. For example, the coating head 54a in the coating unit 53A of the apparatus 50A shown in FIG. 6A intermittently applies the coating 63A along the conveyance direction D of the continuous body 20S and along the width direction W orthogonal to the conveyance direction. Have a structure capable of forming A plurality of applicators 63A are formed at intervals along the transport direction D by the coating head 54, and the applicator row 65 composed of the plurality of applicators 63A aligned along the transport direction D has a width direction W A plurality of rows are formed at intervals.

  Moreover, the application part 53B in apparatus 50B shown to FIG. 6, (b) is provided with two coating heads 54b and 54c. The two coating heads 54b and 54c are arranged in series along the transport direction D of the base sheet 20, and the first coating head 54b is on the upstream side in the transport direction D and on the downstream side than that. The second coating head 54c is disposed. The first coating head 54b applies the composition 60b to the region between the side regions 20b and 20b of the continuous body 20S to form a first coated body 63B. On the other hand, the second coating head 54c forms a second coated body 63C narrower than the first coated body 63B on the first coated body 63B. The second application body 63C is formed to overlap the width direction W of the continuous body 20S, that is, the central portion in the width direction of the first application body 63B. The composition 60b used to form the first application body 63B and the composition 60c used to form the second application body 13C may be different in composition from each other, or may be the same. It may be As a result, the absorber 4b manufactured by the present apparatus 50B has a two-layer structure in the central region in the width direction W, while the side regions located on both sides in the width direction W of the absorber 4b are single-layered It has a structure. Thus, the thickness of the absorber 4b differs between the central region and the side regions, and the absorption performance is also different. Although two coating heads 54 are arranged in series in the apparatus 50B shown in FIG. 6B, two or more coating heads 54 may be disposed so as to form an arbitrary number of layers. Alternatively, the composition 60 may be discharged so as to form a plurality of layers with one coating head 54. Alternatively, the second layer may not be formed at the central portion, and the second layer may be a plurality of layers. Thus, the device 50B can form the absorbent core 14 having a laminated structure composed of a plurality of layers.

As mentioned above, although this invention was demonstrated, this invention is not restrict | limited to embodiment mentioned above, It can change suitably in the range which does not deviate from the meaning of this invention.
For example, the absorbent article of the present invention may be a disposable diaper, a sanitary napkin or the like in addition to the incontinence pad.

  The water-absorbent resin 43 is used for post-treatment of an intermediate resin whose cross-linking condition has been adjusted so that the saturated water absorption amount and the volume increase rate at the time of artificial urine absorption fill the above-mentioned range instead of the crushed material resin mentioned above. It may be without. In addition, the surface treatment method as post-treatment may be performed once or plural times such as twice or three times.

  Hereinafter, the present invention will be described in more detail by way of examples. However, the scope of the present invention is not limited to such embodiments.

Example 1
As a raw material resin, polyacrylic acid sodium salt polymer (manufactured by Sun Diamond Co., Ltd., IM 997) was used. Pulverization of the raw material resin was performed using Labomill LM-05 (manufactured by Dalton Co., Ltd.) to obtain a water-absorbent resin having a median diameter of about 200 μm. The water absorption rate of the water-absorbent resin, the volume increase rate at the time of artificial urine absorption, and the saturated water absorption were measured by the above-mentioned method. The measured values are shown in Table 1.

Example 2
The conditions of pulverization were changed from Example 1 to obtain a water-absorbent resin having a median diameter of about 300 μm. A water absorbent resin was obtained in the same manner as in Example 1 except that the conditions for pulverization were changed.

Comparative Example 1
As Comparative Example 1, IM 997 (median diameter: 457 μm) manufactured by Sun Diamond Co., Ltd. was used without being crushed.

  As shown in Table 1, in comparison with the water absorbent resin of Comparative Example 1, the water absorbent resins of Examples 1 and 2 realize a high water absorption speed while substantially maintaining the saturated absorption amount. Therefore, the absorbent core using the water-absorbent resin of each example can achieve sufficient water absorption speed and absorption capacity without containing pulp fibers, and can be thinner than absorbent cores containing pulp fibers. can do. Furthermore, in the water absorbent resin of Examples 1 and 2, the volume increase rate after artificial urine absorption is lower than that of the water absorbent resin of Comparative Example 1. In the absorbent core containing no pulp fiber, the thickness after absorption is affected by the increase in volume of the water absorbent resin. That is, compared with the case of using the water absorbent resin of Comparative Example 1, the thickness of the absorbent core using the water absorbent resin of each example and not containing pulp fibers is suppressed by 10% or more. From this, the absorbent article in which the absorbent core containing the water-absorbent resin of the example is incorporated can maintain excellent wearing feeling even after liquid absorption.

DESCRIPTION OF SYMBOLS 1 incontinence pad 2 top sheet 3 back sheet 4 absorber 4S continuum 5 side sheet 6 compressed groove 20 base sheet 20S continuum 14 absorbent core 43 water absorbent resin 45 low crosslinked resin 46 highly crosslinked resin 47 water soluble polymer 50 device DESCRIPTION OF SYMBOLS 51 Supply part 51a Tank 51b Agitating blade 51c Shaft 51d Rotational drive source 52 pipe line 53 application part 54 application head 55 drying part 60 composition 63 application body

Claims (6)

An absorbent article comprising a top sheet forming a skin-facing surface, a back sheet forming a non-skin-facing surface, and an absorbent interposed between the two sheets,
The absorbent body comprises a substrate sheet and an absorbent core formed on one side of the substrate sheet,
The absorbent core does not contain pulp fibers, and contains a water-absorbent resin, and a water-soluble polymer that fixes the water-absorbent resin to the base sheet,
The water-absorbent resin contains a low-crosslinked resin having a non-crosslinked portion on the surface, and has a water absorption rate [JIS K 7224 (1996)] of 25 seconds or less, and it is measured by artificial urine absorption according to the following method Absorbent article whose volume increase rate is 16.5 times or less.
<Method of measuring volume increase rate at artificial urine absorption>
A cylindrical plastic tube (inner diameter 30 mm, height 60 mm) provided with a wire mesh (aperture 63 μm, JIS Z8801-1: 2000) at the opening at the lower end was vertically stood and precisely weighed 1.0 g of a water-absorbent resin The water-absorbent resin is placed on a wire mesh so as to have a uniform thickness (stacking height). The deposition height H1 which is the height of the water absorbent resin deposited on the metal mesh is measured. A petri dish provided with a 0.9% by mass sodium chloride solution as artificial urine, and an artificial urine in an amount sufficient for the water-absorbent resin to swell, for example, an amount of 5 or more times the saturated absorption amount of the water-absorbent resin. Prepare. The cylindrical plastic tube is placed in the petri dish with the opening on the wire mesh side facing downward, and the water-absorbent resin is dipped in artificial urine for 30 minutes.
The cylindrical plastic tube is then removed from the petri dish.
Then, on the water absorbent resin that has become lumps due to absorption of artificial urine, a dividing cylinder with an outer diameter of 29.5 mm × thickness 22 mm and a mass of 150 g is placed on the water absorbent resin in the cylindrical plastic tube. Leave for 10 minutes with a load of 0 kPa applied. Next, the mass height H2 which is the height of the mass of the water absorbent resin is measured while the weight is mounted, and the measured mass height H2 is divided by the deposition height H1 to obtain a volume increase rate (H2 // Find H1).   The absorbent article according to claim 1, wherein the low crosslinked resin has the non-crosslinked portion and the crosslinked portion on the surface thereof.   The absorbent article according to claim 1, wherein the low-crosslinking resin is a pulverized product of a water-absorbing resin to which a surface crosslinking treatment has been applied.   The said absorbent body equips only one side of the said base material sheet with an absorptive core, The side in which the said absorptive core of the said base material sheet was formed is not coat | covered with the sheet | seat of another body. The absorbent article according to any one of the above.   The absorbent article according to any one of claims 1 to 4, wherein a surface of the base sheet on which the absorbent core is formed is directed to the back sheet side.   The absorptive article according to any one of claims 1 to 5 whose thickness before absorption of said absorber is 1.5 mm or less.

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