Fixation rate measuring method for water-absorbing resin and fixation rate measuring apparatus for water-absorbing resin

Abstract

To measure the degree of fixation of a water-absorbing resin to an absorber.SOLUTION: A fixation rate measuring method for water-absorbing resin includes: a step which has a longitudinal direction and a width direction, cuts an absorbent article provided with an absorber containing a water-absorbing resin in a crotch part into two in the width direction at a center part in the longitudinal direction, fixes an end in the longitudinal direction of the absorbent article to a falling bar disposed in the horizontal direction, and the cut surface is disposed downward in the vertical direction; a hitting step for impacting the falling bar; a step for obtaining weight of the water-absorbing resin dropped from the absorber; and a fixation rate calculating method which obtains a fixation rate of the water-absorbing resin by an equation of (1-DR / DF)×100 when a quantity of the dropped water-absorbing resin is DR and a quantity of the water-absorbing resin mixed in the absorber by design is DF.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method for measuring the fixation rate of a water-absorbent resin and an apparatus for measuring the fixation rate of a water-absorbent resin. [Background technology]

[0002] 2. Description of the Related Art Absorbent articles such as diapers are known (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-19728 Summary of the Invention [Problem to be solved by the invention]

[0004] An absorbent article has an absorbent body, and the absorbent body contains a water-absorbent resin, which is a highly absorbent polymer that is like sand grains when not absorbing liquid. By using an absorbent body with a high blend ratio of water-absorbent resin, a thin absorbent body can be provided. On the other hand, as the blend ratio of water-absorbent resin is increased, it becomes difficult to keep the water-absorbent resin in a specified position in the absorbent body. In order to verify the appropriate blend ratio of the water-absorbent resin, a method is required to verify the degree to which the water-absorbent resin is fixed to the absorbent body.

[0005] An object of the present invention is to measure the degree to which a water-absorbent resin is fixed to an absorbent body. [Means for solving the problem]

[0006] Specifically, the present invention provides a method for cutting an absorbent article having a longitudinal direction and a transverse direction, and including an absorbent body containing a water-absorbent polymer in a crotch portion, into two pieces in the transverse direction at a longitudinal center portion, fixing the longitudinal ends of the absorbent article to a horizontally disposed drop bar, and disposing the cut surface facing vertically downward; a shaking step of applying an impact to the drop bar; determining a weight of the water-absorbent polymer that has fallen off from the absorbent body; and determining a fixation rate of the water-absorbent polymer by assuming that the amount of the fallen off water-absorbent polymer is DR and the amount of the water-absorbent polymer that is designed to be blended in the absorbent body is DF. (1-DR / DF) x 100 and a method for calculating the fixation rate by the formula: Effect of the Invention

[0007] According to the present invention, it is possible to measure the degree to which the water-absorbent resin is fixed to the absorbent body. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a diaper. [Diagram 2] FIG. 2 is an exploded perspective view of the diaper. [Diagram 3] FIG. 3 is a cross-sectional view of the diaper when not being worn, taken along the width direction at the center in the longitudinal direction. [Figure 4] FIG. 4 is a diagram showing the appearance of an apparatus for measuring the fixation rate of a water-absorbent resin. [Diagram 5] FIG. 5 is a diagram showing the state in which the drop bar is raised. [Figure 6] FIG. 6 is a diagram showing an example of a fixation rate measuring device for collecting a water-absorbent resin. [Figure 7] FIG. 7 is a flow chart showing a method for measuring the fixation rate of a water-absorbent resin. [Figure 8] FIG. 8 is a flow chart showing another example of the method for measuring the fixation rate of a water-absorbent resin. [Figure 9] FIG. 9 is a graph showing the relationship between the fixation rate of the water-absorbent resin and the ratio of the water-absorbent resin. [Figure 10] FIG. 10 is a diagram showing the operation of the cam when the striking process is performed by the electric motor. [Figure 11] FIG. 11 is a diagram showing another example of the fixation rate test of the water-absorbent resin. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, absorbent articles according to embodiments of the present invention will be described with reference to the drawings. Note that the configurations of the following embodiments are merely examples, and the present invention is not limited to the configurations of these embodiments.

[0010] <Embodiment> FIG. 1 is a perspective view of a diaper. The diaper 1 shown in FIG. 1 is a disposable diaper for children that is an example of an absorbent article. The diaper 1 has a crotch region 1B that corresponds to the crotch of the wearer covering the pubic area when worn, a front body region 1F that is located in front of the crotch region 1B and corresponds to the front body of the wearer, and a rear body region 1R that is located behind the crotch region 1B and corresponds to the rear body of the wearer. Tapes 2L and 2R having hook tapes that can be attached to a front patch 2F provided on the non-wearer side surface of the front body region 1F are provided on the left and right edges of the rear body region 1R. When the tapes 2L and 2R are attached to the front patch 2F with the front body region 1F positioned on the wearer's abdomen and the rear body region 1R positioned on the wearer's back, the diaper 1 is fixed to the wearer's body in a state where it surrounds the wearer's waist circumference and thighs. Since the diaper 1 is fixed to the wearer's body in this manner, the wearer can stand and walk around while wearing the diaper 1.

[0011] In the diaper 1, an absorbent capable of absorbing and retaining liquid is mainly disposed near the crotch region 1B. In addition, in order to prevent the formation of a gap between the diaper 1 and the wearer's skin that can be a liquid outflow path, the diaper 1 is provided with leg gathers 3AL, 3AR at a portion surrounding the wearer's legs (thighs), and three-dimensional gathers 3BL, 3BR are provided on the inner side of the leg gathers 3AL, 3AR in the width direction of the diaper 1, and a waist gather 3R is provided at a portion surrounding the wearer's abdominal circumference. The leg gathers 3AL, 3AR, the three-dimensional gathers 3BL, 3BR, and the waist gathers 3R are in close contact with the wearer's skin by the elastic force of the elastic members. Therefore, liquid discharged from the wearer's private parts is absorbed by the absorbent of the diaper 1 without leaking out of the diaper 1. As the elastic member, a thread-like or strip-like rubber or the like can be appropriately selected.

[0012] FIG. 2 is an exploded perspective view of the diaper 1. FIG. 3 is a cross-sectional view of the diaper 1 when not worn, cut along the width direction at the center in the longitudinal direction. The diaper 1 has a cover sheet 4 that forms the outer surface when worn. The cover sheet 4 is a sheet-like member having a substantially rectangular appearance with a constriction at the portion corresponding to the long side, and forms the exterior surface of the diaper 1. The cover sheet 4 is provided to reinforce the back sheet 5 described later and to improve the feel. For example, in order to suppress leakage of excrement, a nonwoven fabric made of a liquid-impermeable thermoplastic resin can be used as the material for the cover sheet 4. Examples of liquid-impermeable thermoplastic resins include polyethylene (PE) and polypropylene (PP). The cover sheet 4 is not limited to a single-layer structure, and may be a multi-layer structure having an inner cover sheet and an outer cover sheet.

[0013] The diaper 1 has a back sheet 5 (non-skin facing sheet), an absorbent body 6, and a top sheet 7 (skin facing sheet) which are laminated in this order on the skin facing side of the cover sheet 4. The back sheet 5, the absorbent body 6, and the top sheet 7 are all sheet-like members having a substantially rectangular appearance, and are laminated in this order on the cover sheet 4 with their longitudinal directions coinciding with the longitudinal direction of the cover sheet 4. The back sheet 5 is a sheet formed of a water-impermeable thermoplastic resin material to suppress leakage of excrement, similar to the cover sheet 4. The back sheet 5 is preferably made of a material that is also moisture-permeable to suppress stuffiness when worn. The top sheet 7 is a sheet-like member arranged on the wearer's skin side. The top sheet 7 is liquid-permeable in part or in whole. Therefore, when the diaper 1 is worn, liquid excreted from the wearer passes through the top sheet 7 that may come into contact with the wearer's skin and enters the absorbent body 6, where it is absorbed. For example, woven fabric, nonwoven fabric, and porous film can be used as the material for the top sheet 7. The top sheet 7 may be hydrophilic. The absorbent body 6 is arranged to include the crotch region 1B.

[0014] The back sheet 5, absorbent body 6, and top sheet 7 all extend from the front body region 1F to the rear body region 1R. Therefore, when the wearer's private parts are covered with the cover sheet 4 in which the back sheet 5, absorbent body 6, and top sheet 7 are laminated, both ends in the longitudinal direction of the back sheet 5, absorbent body 6, and top sheet 7 are located on the wearer's ventral side and back side. In other words, the wearer's private parts are covered by the absorbent body 6 from the wearer's ventral side to the back side. Therefore, whether the wearer is in a ventral or back-facing position when excreting liquid, the excreted liquid comes into contact with the absorbent body 6 via the top sheet 7.

[0015] The diaper 1 also has long, narrow, strip-like side sheets 8L, 8R. The side sheets 8L, 8R are liquid-impermeable sheets provided on the long sides of the top sheet 7. Like the cover sheet 4, the side sheets 8L, 8R are provided with constrictions at the locations where the wearer's thighs are located. The side sheets 8L, 8R have elastic members 8EL, 8ER arranged along the longitudinal direction for forming three-dimensional gathers 3BL, 3BR. When the diaper 1 is worn, i.e., when the diaper 1 is U-shaped in side view, the side sheets 8L, 8R are pulled in the longitudinal direction by the contractile force of the elastic members 8EL, 8ER and rise from the top sheet 7 to form three-dimensional gathers 3BL, 3BR that prevent liquid from leaking out.

[0016] The absorbent body 6 according to this embodiment has a substantially rectangular shape. If the absorbent body is made gourd-shaped, it may bend at the constricted portion near the crotch region 1B, but since the absorbent body 6 is rectangular, it is resistant to bending in the entire longitudinal region. The absorbent body 6 has an absorbent core 6C and a core wrap sheet 6W that wraps the absorbent core 6C. The core wrap sheet 6W is made of a water-permeable sheet, and allows liquid that has passed through the top sheet 7 to flow into the absorbent core 6C. The core wrap sheet 6W may be made of a single sheet, or may be divided into a sheet that covers the skin-facing side of the absorbent core 6C and a sheet that covers the side and non-skin-facing sides of the absorbent core 6C, and may be configured by bonding them together near the side or skin-facing side widthwise end. The absorbent core 6C and the core wrap sheet 6W are bonded to prevent the absorbent core 6C from losing its shape.

[0017] The absorbent core 6C has a structure in which granular water-absorbing resin such as SAP (Super Absorbent Polymer), which is a hydrophilic polymer having a cross-linked structure capable of absorbing and retaining water, is held in the gaps between short fibers of cellulosic fibers such as pulp fibers, rayon fibers, or cotton fibers, or short fibers obtained by hydrophilizing synthetic fibers such as polyethylene, polypropylene, or polyethylene terephthalate. The water-absorbing resin in this embodiment refers to a granular resin composition containing SAP. The term "SAP-containing resin composition" as used herein includes both a composition consisting of SAP alone and a composition containing SAP as the main component and containing other substances to the extent that they do not adversely affect the water absorption. Examples of "other substances" include additives (such as surface modifiers added to hydrophobize the particle surfaces), unreacted monomers remaining during the synthesis of SAP, and the like.

[0018] Nowadays, there is an increasing demand for small and not bulky absorbent articles, and the absorbent body 6 is thinned. However, simply making the absorbent 6 thinner leads to leakage of discharged liquid such as urine, so it is necessary to reduce the proportion of short fibers contained in the absorbent 6 and increase the proportion of water-absorbent resin. The content of water-absorbent resin in the absorbent core of a general diaper is about 50% by mass, but the content of water-absorbent resin in this embodiment is 60% or more, more specifically 62% by mass or more, which is higher than that of a general diaper. In addition, the average particle diameter of the water-absorbent resin in the embodiment is in the range of 300 to 600 μm, and the water-absorbent resin is entangled with the short fibers and is relatively difficult to move inside the absorbent core 6C. However, the water-absorbent resin in a state where it has not absorbed moisture is hard and sand-like and easily flows. If the water-absorbent resin flows in response to the wearer's movements, it may accumulate in the crotch area, for example, and affect the wearing comfort. In addition, it is considered that the flow makes it difficult to obtain an appropriate absorption effect.

[0019] In addition, the water-absorbing resin that has moved outside the absorbent body 6 may contaminate the manufacturing equipment during the manufacturing process. If the water-absorbing resin gets mixed into the manufacturing equipment, it may adhere to a hot melt adhesive coating device, causing coating defects, or may accumulate in the manufacturing equipment and then get mixed into the product, leading to poor quality. Therefore, it is desirable to keep the water-absorbing resin inside the absorbent body 6 as much as possible during the manufacturing process.

[0020] In conventional absorbent articles, the flow of the water-absorbent resin is suppressed by short fibers, but there is a possibility that the flow of the water-absorbent resin will occur more easily by reducing the proportion of short fibers. If it is possible to investigate the extent to which the water-absorbent resin is fixed inside the absorbent body 6, it will be possible to manufacture absorbent articles that are both thin and maintain their functionality.

[0021] In this embodiment, an example of an absorbent article is shown using a tape-type disposable diaper for children, but the absorbent article for which the fixation rate of the water-absorbent resin can be measured in the present invention is not limited to this, and any type of absorbent article may be used as long as it has an absorbent body containing a water-absorbent resin. For example, a pants-type disposable diaper for children may be used as an example of an absorbent article. Also, pants-type and tape-type diapers for adults may be used as an example of an absorbent article, and a urine pad may be used.

[0022] FIG. 4 is a diagram showing the appearance of a fixation rate measuring device for a water-absorbent resin. The fixation rate measuring device 10 includes two support columns 11 arranged at an interval, a horizontal bar 13 fixed to the support columns 11 and connecting the support columns 11, a guide member 15 attached to the horizontal bar near the support columns 11 and having a guide rail 16 on the inside, a drop bar 14 which is a metal bar attached so as to be movable on the inside of the guide rail 16, and a protrusion 17 which supports the guide member 15. A height adjustment device 12 is arranged on the vertical lower side of the support columns 11, and the height of the support columns 11 can be adjusted while keeping the drop bar 14 horizontal. An example of the height adjustment device is a jack such as a lab jack. Using a jack is preferable because it allows the height of the support columns 11 to be adjusted steplessly. Any means other than a jack may be used to adjust the height.

[0023] Inside the two support posts 11, a hook tape of a hook-and-loop fastener is arranged on the surface of the drop bar 14, and the nonwoven fabric surface of the absorbent article including the absorbent body 6 can be engaged and fixed to the center of the drop bar 14. It may be clamped with a clip or the like. It may be fixed without the hook tape. In the embodiment shown in FIG. 4, the absorbent body 6 cut from the diaper 1 and cut in the width direction in the crotch region 1B into two is engaged with the drop bar 14 and hangs down with the cut surface facing down. A tray 19, which is a tray-shaped tray for example, is arranged vertically below the absorbent body 6, and the water-absorbing resin that falls from the absorbent body 6 is accumulated in the tray 19. An electronic balance 20 is arranged below the tray 19, and the tray 19 is structured to be placed on the electronic balance 20.

[0024] A plurality of suppression plates 18 are arranged on the sides of the absorber 6 so that the vertically downward side is narrower. The suppression plate 18 is disposed to suppress the water-absorbent resin that has fallen from the absorbent body 6 from scattering outside the receiving tray 19. The suppression plate 18 is separately supported by a supporting means (not shown), and does not affect the measurement value of the electronic balance 20. The suppression plate 18 and the receiving tray 19 are an example of a collecting means for collecting the water-absorbent resin that has fallen from the absorbent body 6.

[0025] The drop bar 14 can move vertically in the movable area defined by the guide rail 16, i.e., it can be lifted and dropped. The guide rail 16 is a rail that guides the drop bar 14 so that it moves linearly in the vertical direction, i.e., it can be lifted and dropped. The lower end of the guide rail 16 also functions as a stopper. That is, the lower end of the guide rail 16 is arranged below the drop bar 14 in the vertical direction, and collides with the drop bar 14 that falls vertically, giving an impact to the drop bar 14 and separating the water-absorbing resin from the absorbent body 6. Note that the guide rail 16 is not necessarily required as long as there is an upper end portion and a lower end portion that serves as a stopper. However, by providing the guide rail 16, it becomes easier to guide the drop bar 14 to fall the shortest distance in a straight trajectory along the vertical direction, so that the experimental conditions can be made constant. FIG. 4 shows an example in which two absorbers 6 are fixed to the drop bar 14, but if only one absorber 6 is fixed, the entire device can be made compact, and if three or more absorbers 6 are fixed and measured, the number of measurements per hour increases, making it more efficient.

[0026] FIG. 5 is a diagram showing a state in which the drop bar is lifted. The drop bar 14 can move vertically within the range indicated by the arrow in FIG. 5, that is, the range defined by the guide rail 16. When conducting a test, an experimenter holds both ends of the drop bar 14, lifts the drop bar vertically to the upper end of the guide rail 16 as shown in this figure, and releases the hands, causing the drop bar 14 to freely fall vertically along the guide rail 16 in a straight trajectory for the shortest distance (striking operation). Both ends of the fallen drop bar 14 collide with the stopper, which is the lower end of the guide rail 16, and impact the absorbent body 6 placed thereon. The absorbent resin that is not fixed falls off from the cut surface of the absorbent body 6 that has been impacted. This striking operation is repeated a predetermined number of times. As an example, it is performed 20 times. It is also possible to change the number of impacts in consideration of the actual movement of the wearer. The length of the guide rail 16 may be set according to the wearer assumed for the absorbent article. In this embodiment, since the diaper 1 is a tape-type diaper for babies, the length of the guide rail 16 is set to 10 cm as an assumed vertical movement in accordance with the daily movements of a child, and this is set as the predetermined falling distance. In this manner, the predetermined distance indicated in this application is a distance set based on the assumed vertical movement of the wearer of the absorbent article when walking, etc.

[0027] Fig. 6 is a diagram showing an example of a fixation rate measuring device for collecting water-absorbent resin. A tray 19 is arranged vertically below the absorbent body 6 arranged on the drop rod 14. The water-absorbent resin 21 detached from the absorbent body 6 due to the application of an impact to the drop rod 14 accumulates in the tray 19 arranged vertically below. In addition, a suppression plate 18 is arranged diagonally above the tray 19 so that the vertically lower side is narrowed. The suppression plate 18 prevents the water-absorbent resin 21 from scattering outside the range of the tray 19 due to the impact applied to the drop rod 14.

[0028] An electronic balance 20 is disposed vertically below the tray 19, and the tray 19 is placed on the electronic balance 20. When the drop bar 14 is dropped to impact the absorbent body 6, the water absorbent resin 21 detached from the absorbent body 6 accumulates on the tray 19 directly or via the suppression plate 18. The weight of the water absorbent resin 21 detached from the absorbent body 6 can be obtained from the measurement value of the electronic balance 20. If the amount of the detached water absorbent resin 21 is DR and the amount of the water absorbent resin 21 blended in the absorbent body 6 by design is DF, the fixation rate (%) of SAP can be obtained by the formula (1-DR / DF)×100. The fixation rate of the water absorbent resin 21 contained in the absorbent body 6 can be measured by this fixation rate calculation method. The fixation rate is preferably closer to 100%.

[0029] The striking action of applying an impact to the drop rod 14 to separate the water-absorbent resin 21 from the absorbent body 6 is , can be performed multiple times. The weight of the water absorbent resin 21 finally obtained can also be measured. In addition, the shaking operation may be repeated while measuring and accumulating the degree of accumulation in the tray 19 for each shaking operation. By performing the measurement for each shaking operation, the characteristics of the absorbent body 6 can be more easily understood. For example, if the water absorbent resin 21 falls after several shaking operations and almost no water absorbent resin 21 falls in the subsequent shaking operations and the fixing rate is low, it means that almost no water absorbent resin 21 is fixed to the absorbent body 6 and uneven distribution of the water absorbent resin 21 contained in the absorbent article may occur due to the movement of the wearer.

[0030] FIG. 7 is a flow chart showing a method for measuring the fixation rate of the water-absorbent resin. First, the absorbent body 6 is cut into two pieces at the center in the longitudinal direction, and the ends in the longitudinal direction are fixed to a horizontally arranged drop bar, and the cut surface is placed on the drop bar 14 with the cut surface facing vertically downward (step S101). Next, the drop bar 14 is dropped a predetermined distance a predetermined number of times along the guide rail 16 (shaking step) (step S102). This operation is repeated a number of times (variable n is set to 1, n is added each time, and n reaches N_MAX) until all the particles not fixed inside the absorbent body 6 have fallen. A specific number of times is 20 times, for example. The number of times may be set arbitrarily depending on the use and function of the absorbent article. The predetermined distance, the falling distance, may be 10 cm, for example, and may be set arbitrarily depending on the use and function of the absorbent article. When the dropping operation is completed, the amount of the water-absorbent resin that has fallen from the absorbent body 6 is measured (step S103). Then, the fixation rate of the water-absorbent resin is calculated from the amount of the water-absorbent resin designed to be blended in the absorbent body 6 and the amount of the dropped water-absorbent resin by the fixation rate calculation method already described (step S104). By this method, the fixation rate of the water-absorbent resin can be calculated.

[0031] Fig. 8 is a flow chart showing another example of the method for measuring the fixation rate of the water-absorbent resin. The step of placing the cut absorbent body 6 on the drop bar (step S201) and the step of dropping the drop bar 14 along the guide rail 16 (step S202) are the same, but the difference is that the amount of water-absorbent resin dropped for each shaking operation is weighed (step S203) and the fixation rate is calculated (step S204). That is, in the method shown in Fig. 8, the fixation rate of the water-absorbent resin is integrated for each shaking process that is repeated multiple times. According to this method, the fixation degree of the water-absorbent resin can be analyzed in more detail as the shaking process progresses, and the characteristics of the absorbent body 6 can be more easily understood.

[0032] FIG. 9 is a graph showing the relationship between the fixation rate of the water-absorbent resin and the ratio of the water-absorbent resin. From FIG. 9, it can be seen that the fixation rate of the water-absorbent resin deteriorates as the ratio of the water-absorbent resin contained in the absorbent body 6 increases. In FIG. 9, the area surrounded by the dotted line is a range in which the water-absorbent resin is sufficiently fixed, does not affect the wearing comfort, and does not cause malfunction of the manufacturing device in the manufacturing process. The content ratio of the water-absorbent resin contained in the absorbent body of a general diaper is 50 mass %, and the water-absorbent resin is almost completely fixed, so there is no need to consider the water-absorbent resin in the manufacturing process. In contrast, the content ratio of the water-absorbent resin in the present embodiment is 60% or more, and it can be seen that there is a possibility that it may move, affect the wearing comfort, or cause problems in the manufacturing process. For this reason, it can be said that in the diaper 1 according to this embodiment, it is necessary to take care not to scatter the water-absorbent resin not only when wearing it, but also in the manufacturing process.

[0033] FIG. 10 is a diagram showing the operation of the cam when the vibration process is performed by an electric motor. In the above embodiment, the operator lifts the drop rod 14 to the top end of the guide rail 16 and releases it to perform the vibration process. However, this places a heavy burden on the experimenter, so the vibration process is automated by using an electric motor. FIG. 10(A) is a diagram showing an example of a cam and a cam curve showing the operation of the follower of the cam rotating on the same axis. A cam is a mechanical element that changes the direction of movement, and the cam curve showing the position of the follower when the magatama-shaped cam 22 shown in FIG. 10(A) rotates in the direction of the arrow is, for example, as shown in the figure. The follower rises as the cam 22 rotates, and returns to its original position at the step part at once, generating an impact, functioning as a so-called stamper.

[0034] FIG. 10(B) is a diagram showing in more detail an example in which a cam mechanism is incorporated into a water-absorbent resin fixation rate measuring device. As shown in FIG. 10(B), the shaft of the cam 22 is disposed on the protruding portion 17. The cam 22 is rotated in the direction of the arrow by an electric motor. The follower of the cam 22 is the drop bar 14. As the cam 22 rotates, the drop bar 14 is lifted from the lower end to the upper end of the guide rail 16, and when it passes the step of the cam, it falls according to gravity and collides with the lower end of the guide rail 16. This impact causes the water-absorbent resin to fall from the absorbent body 6 disposed on the drop bar 14. The relationship between the cam curve of the cam 22 and the actual movable range of the drop bar 14 is as shown in the figure.

[0035] Two cams 22 are arranged along the support 11, and their rotation speeds may be synchronously controlled by an externally controllable motor such as a stepping motor or a servo motor. This allows the drop bar 14 to be kept horizontal at all times. Each motor may be connected to a control device (not shown) and operated by commands from the control device. By using the control device, the number of rotations of the motors can be controlled, making it possible to realize a desired number of swinging motions.

[0036] FIG. 11 is a diagram showing another example of the fixation rate test of the water-absorbent resin. The outline of the test apparatus and the test method are the same as those described above, but in the example shown in FIG. 11, the absorbent body 6 is placed in the test apparatus while covered with a resin bag 23. The bag 23 is made of polypropylene or polyethylene, for example. In the example shown in FIG. 11, the water-absorbent resin 21 that falls off the absorbent body 6 due to the impact of the drop bar 14 is accumulated at the bottom of the bag 23, not on the electronic balance 20. After the drop operation is completed several times, the content of the bag 23 is weighed by a separately prepared electronic balance, and the amount of the water-absorbent resin 21 that falls off the absorbent body 6 is calculated.

[0037] In the experimental method shown in FIG. 11, the absorbent body 6 is covered with a bag 23. The water-absorbent resin 21 may scatter to places other than under the experimental apparatus due to the impact of the fall, but by covering the absorbent body 6 with the bag 23, the scattered water-absorbent resin 21 can be reliably captured, and the amount of water-absorbent resin that is not fixed to the absorbent body 6 can be measured more accurately. The content of the formula for calculating the fixation rate (%) of the water-absorbent resin is the same as that described above. The bag 23 is also an example of a collection means for collecting the water-absorbent resin 21 that has fallen off the absorbent body 6.

[0038] Although the present embodiment has been described above, the contents of the present invention are not limited to the above embodiment. In the present embodiment, an electric cam is used to automate the shaking process, but the shaking process can be automated by other methods. For example, the vertical movement of the drop bar 14 can be realized by a linear motor. In addition, the operation of giving an impact to the drop bar 14 is not necessarily limited to the shaking operation, and can be realized by giving strong vibration to the drop bar 14 arranged with a play by an eccentric motor or a linear actuator.

[0039] The features included in each of the embodiments and the modified examples thereof disclosed above can be combined with each other. [Explanation of symbols]

[0040] 1. Diapers 1B...Inseam area 1F: Front body area 1R: Back body area 2L, 2R... Elastic body 3BL, 3BR Elastic body 3L, 3R: 3D gathers 4. Cover sheet 5. Back sheet 6. Absorber 6C··Absorbent core 6W··Core wrap sheet 7. Top sheet 8R, 8L··Side seat 10...Fixed rate measuring device 11...post 12...Adjustment device 13...Horizontal bar 14. Falling pole 15 Guide material 16 Guide rail 17...Protrusion 18...Suppression plate 19. Tray 20·Electronic balance 21...Water absorbent resin 22 Cam 23 bags

Claims

1. a step of cutting an absorbent article having a longitudinal direction and a width direction and including an absorbent body containing a water-absorbent polymer in a crotch portion into two pieces in the width direction at a central portion in the longitudinal direction, fixing the longitudinal ends of the absorbent article to a horizontally disposed drop bar, and arranging the cut surface facing vertically downward; A shaking process for impacting the drop bar; determining the weight of the water-absorbent resin that has fallen off from the absorbent body; When the amount of the water absorbent resin that has fallen off is DR and the amount of the water absorbent resin that is designed to be blended in the absorbent body is DF, the fixation rate of the water absorbent resin is expressed as follows: (1-DR / DF)×100 The fixed rate calculation method is as follows: A method for measuring a fixation rate of a water-absorbent resin, comprising:

2. The shaking step includes dropping the drop bar a predetermined distance in a vertical direction, A step of colliding the dropping rod with a stopper arranged vertically below the dropping rod. The method for measuring the fixation rate of the water-absorbent resin according to claim 1.

3. The shaking step includes a step of dropping the drop bar along a guide rail provided so as to drop the drop bar along a straight trajectory in the shortest distance toward the stopper, The method for measuring the fixation rate of a water-absorbent resin according to claim 2.

4. The shaking step includes a step of placing the absorbent article in the center of the drop bar, holding both ends of the drop bar and lifting the drop bar vertically, and then allowing the drop bar to freely fall so that both ends of the drop bar collide with the stoppers. The method for measuring the fixation rate of a water-absorbent resin according to claim 2.

5. The step of determining the weight of the water absorbent resin that has fallen off from the absorbent body includes a method of collecting the water absorbent resin that has fallen off from the absorbent body and measuring the weight thereof. The method for measuring the fixation rate of the water-absorbent resin according to claim 1.

6. After repeating the shaking step multiple times, the weight of the water-absorbent resin that has fallen off from the absorbent body is measured. The method for measuring the fixation rate of a water-absorbent resin according to claim 5.

7. The shaking step is repeated a plurality of times, and the weight of the water absorbent resin that has fallen off from the absorbent body is accumulated for each shaking step. The method for measuring the fixation rate of a water-absorbent resin according to claim 5.

8. A drop bar capable of fixing an absorbent body of an absorbent article; A guide rail that guides the drop bar so that the drop bar can repeatedly fall a predetermined distance in a straight line in the vertical direction; A stopper that applies impact to the dropped drop bar; A collecting means for collecting the water-absorbent resin that has fallen off from the absorbent body; An apparatus for measuring a fixation rate of a water-absorbent resin comprising:

9. A mechanism for raising the drop bar by the movement of an electric motor is provided. The apparatus for measuring the fixation rate of a water-absorbent resin according to claim 8.

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