Method for manufacturing an absorbent article

Abstract

To prevent an indicator to inform a replacement time from discoloring before use.SOLUTION: Concerning a manufacturing method of an absorbent article, in a step for manufacturing the absorbent article, second hot melt is applied onto a back sheet solidified by applying first hot melt thereto, and an absorber around which a core wrap sheet is wound is brought into contact therewith before the second hot melt is solidified, to thereby allow the second hot melt to penetrate between fibers of the core wrap sheet, and the absorber around which the core wrap sheet is wound and the back sheet are bonded together.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an absorbent article.

Background Art

[0002] Diapers, which are absorbent articles, are designed to absorb the wearer's excretions as quickly as possible and to improve the wearer's comfort as much as possible even when there is excrement. However, it is difficult to completely eliminate the discomfort of the wearer, and from a hygiene perspective, it is preferable to be replaced immediately after excrement is generated.

[0003] For this reason, in order to enable visual determination of the wearer's urination from the outside, there is a device in which a replacement notification indicator that changes color when it comes into contact with urine is incorporated in a component that can be visually recognized from the outside. The indicator is known, for example, as a hot melt that is applied to the non-skin side sheet of the absorber and changes color when it comes into contact with urine (Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When a diaper is placed in an actual environment such as high temperature and high humidity, the indicator may react to the moisture in the air and change color before being worn. If the indicator has changed color before being worn, it is not possible to visually recognize from the outside the timing of diaper replacement.

Means for Solving the Problems

[0006] In order to solve the above problems, the present invention uses a manufacturing process in which a hot melt serving as an indicator does not penetrate into the core wrap sheet.

[0007] Specifically, the present invention relates to a method for manufacturing an absorbent article, which comprises applying a second hot melt onto a backsheet coated with and solidified by a first hot melt, and bringing an absorber wrapped with a core wrap sheet into contact with the second hot melt before the second hot melt solidifies, so that the second hot melt penetrates between the fibers of the core wrap sheet, and then adhering the absorber wrapped with the core wrap sheet to the backsheet.

[0008] The first hot melt may be previously applied to the backsheet and solidified.

[0009] The first hot melt is applied to the backsheet before the second hot melt is applied, and may be solidified when the second hot melt is applied.

[0010] A cooling device for cooling the hot melt is provided between the application position of the first hot melt and the application position of the second hot melt. The first hot melt is cooled by the cooling device after being applied and before the second hot melt is applied, and may be solidified when the second hot melt is applied.

[0011] The first hot melt may contain a component whose color changes when it comes into contact with a liquid.

Advantages of the Invention

[0012] According to the present invention, discoloration due to moisture absorption of the indicator can be prevented even in an actual environment such as high temperature and high humidity. Therefore, the function of the indicator is not impaired even in diapers stored in a somewhat harsh environment.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0014] Hereinafter, with reference to the drawings, the manufacturing process of the absorbent article according to the embodiment of the present invention will be described. Note that the configurations of the following embodiments are examples, and the present invention is not limited to the configurations of these embodiments.

[0015] In the present embodiment, for a tape-type disposable diaper (an example of the "absorbent article" referred to in the present application, hereinafter simply referred to as "diaper"), the direction connecting the front body portion disposed facing the abdomen of the wearer and the back body portion disposed facing the back is defined as the longitudinal direction. Between these front body portions (one side in the longitudinal direction) and the back body portions (the other side in the longitudinal direction) (the center in the longitudinal direction), there is a crotch portion disposed under the crotch of the wearer (opposite to the crotch). Further, in the state where the diaper is worn on the wearer (hereinafter abbreviated as the "worn state"), the side facing the skin of the wearer (the inner side in the worn state) is defined as the skin surface side, and the side opposite to the skin surface side (the outer side in the worn state) is defined as the non-skin surface side. Furthermore, the direction connecting the skin surface side and the non-skin surface side is defined as the thickness direction, and the direction orthogonal to both the longitudinal direction and the thickness direction is defined as the width direction. In addition, viewing from the thickness direction is defined as a plan view.

[0016] FIG. 1 is a perspective view of a diaper according to the present embodiment. The diaper 1 has a crotch region 1B, which is a region corresponding to the crotch of the wearer covering the pubic area when worn, a front body region 1F, which is located in front of the crotch region 1B and corresponds to the front body of the wearer, and a back body region 1R, which is located behind the crotch region 1B and corresponds to the back body of the wearer. Tapes 2L and 2R 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 both left and right edges of the back body region 1R. When the tapes 2L and 2R are attached to the front patch 2F with the front body region 1F arranged on the wearer's abdominal side and the back body region 1R arranged on the wearer's back side, the diaper 1 is fixed to the wearer's body in a state surrounding the wearer's abdominal circumference and thighs. Since the diaper 1 is fixed to the wearer's body in this manner, the wearer can stand and walk while wearing the diaper 1.

[0017] 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 inside 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. Note that the elastic member may be a thread-like or strip-like rubber or the like.

[0018] Figure 2 is an exploded perspective view of the diaper 1. The diaper 1 has a cover sheet 4 that forms the outer surface in the worn state. The cover sheet 4 is a sheet-like member having a substantially rectangular appearance with gathers 4KL and 4KR provided at a portion corresponding to the long side, and forms the exterior surface of the diaper 1. The gathers 4KL and 4KR are provided at a portion where the wearer's thighs are located. The cover sheet 4 is provided for reinforcing the back sheet 5 and improving the touch described later. For example, in order to suppress leakage of body fluids, a liquid-impermeable non-woven fabric made of a thermoplastic resin can be used as its material. Examples of the thermoplastic resin include polyethylene (PE) and polypropylene (PP). The cover sheet 4 is not limited to a single-layer structure and may have a multi-layer structure having an inner cover sheet and an outer cover sheet.

[0019] And the diaper 1 has a back sheet 5, an absorber 6, and a top sheet 7 that are sequentially laminated on the surface of the cover sheet 4 on the wearer side. The back sheet 5, the absorber 6, and the top sheet 7 are all sheet-like members having a substantially rectangular appearance, and are sequentially laminated on the cover sheet 4 in a state where the longitudinal direction coincides with the longitudinal direction of the cover sheet 4. The back sheet 5 is a sheet formed of a liquid-impermeable thermoplastic resin as a material in order to suppress leakage of body fluids, like the cover sheet 4. The back sheet 5 functions as a moisture-proof film. Also, the top sheet 7 is made of an air-through non-woven fabric formed by including fibers of a thermoplastic resin, and is disposed on the skin surface side of the wearer so as to cover the water-absorbing surface of the absorber 6. This top sheet 7 has liquid permeability in part or all of it. Therefore, in a state where the diaper 1 is worn, the body fluids discharged from the wearer enter the absorber 6 through the top sheet 7 that can come into contact with the wearer's skin, and are absorbed there. Also, the top sheet 7 may have hydrophilicity. Note that the longitudinal direction of the diaper 1 is the same as the longitudinal direction of the absorber 6 and the top sheet 7.

[0020] The backsheet 5, the absorber 6, and the topsheet 7 all extend from the front crotch region 1F to the rear crotch region 1R. Therefore, when the crotch of the wearer is covered with the cover sheet 4 in which the backsheet 5, the absorber 6, and the topsheet 7 are laminated, both longitudinal ends of the backsheet 5, the absorber 6, and the topsheet 7 are in a state of being located on the ventral side and the dorsal side of the wearer. That is, the crotch of the wearer is in a state of being covered by the absorber 6 from the ventral side to the dorsal side of the wearer. Therefore, no matter whether the wearer discharges the liquid out of the body in a posture with the abdomen facing downward or a posture with the back facing downward, the discharged liquid will contact the absorber 6 through the topsheet 7.

[0021] FIG. 3 is a cross-sectional view of the central part (crotch region) of the diaper according to the embodiment. Each sheet is formed so as to wrap the absorber 6, and at the part where the absorber, each sheet, and the sheets overlap, they are adhered to each other with an adhesive such as hot melt. The free ends of the side sheets 8L and 8R rise along the side surface of the absorber 6 and are biased by an elastic body to function as three-dimensional gathers 3BL and 3BR. The absorber 6 is a granular absorbent resin (high molecular water-absorbing material) such as SAP (Super Absorbent Polymer), which is a hydrophilic polymer having a cross-linked structure capable of absorbing and retaining water, in the gaps between short fibers of cellulosic fibers such as pulp fibers, rayon fibers, or cotton fibers, and short fibers obtained by subjecting synthetic fibers such as polyethylene, polypropylene, or polyethylene terephthalate to a hydrophilic treatment.

[0022] The SAP particles in the present embodiment refer to those in which a resin composition containing SAP is formed into a granular shape. The "resin composition containing SAP" mentioned here is a concept that includes both a composition consisting only of SAP and a composition having SAP as a main component and containing other substances to such an extent that it does not adversely affect water absorption. Examples of the "other substances" include additives (such as surface modifiers added for the purpose of hydrophobizing the particle surface) and unreacted monomers remaining during the synthesis of SAP.

[0023] The absorber 6 is wrapped by the core wrap sheet 9. The core wrap sheet 9 is a thin sheet with water permeability, composed of non-woven fabric or the like, which does not prevent the absorber 6 from absorbing the discharged matter, but plays a role in preventing the absorber 6 from collapsing and preventing the SAP particles contained in the absorber 6 from scattering to other structures.

[0024] Hot melt 30 is applied to the skin side of the back sheet 5 to regulate the position of the absorber 6 wrapped by the core wrap sheet 9. Also, several of the applied hot melts are hot melt 31 containing components that change color due to moisture contained in urine, changes in pH, etc. The hot melt 31 serves as an indicator to notify the diaper replacement time. The back sheet is semi-transparent, and since the discoloration of the hot melt 31 can be easily visually recognized from the non-skin side of the diaper, the replacement time can be easily determined. For diapers equipped with a cover sheet, it is desirable that the indicator equivalent part of the cover sheet is semi-transparent.

[0025] When the diaper as described above is placed in an actual environment, it is known that the indicator may change color before use. As a result of the inventor's experimental verification, it was found that there are roughly two factors for the discoloration. The first factor is that the core wrap sheet 9 itself that comes into contact with the indicator absorbs moisture. When the core wrap sheet 9 absorbs moisture, the moisture is transmitted to the indicator that comes into contact with the core wrap sheet, and the indicator changes color.

[0026] The second factor is that the hot melt 31 that constitutes the indicator penetrates into the voids of the fibers forming the core wrap sheet 9. When the diaper is placed in a harsh environment such as high temperature and high humidity in such a state, moisture is transmitted from the absorbed absorber 6, and the indicator changes color.

[0027] That is, in order to suppress the discoloration of the indicator before using the diaper, it is necessary to configure the core wrap sheet 9 with a moisture-absorbing material and prevent the hot melt 31 that becomes the indicator from penetrating into the voids of the fibers forming the core wrap sheet 9.

[0028] Examples of the water-permeable but non-moisture-absorbing core wrap sheet 9 include resin non-woven fabrics rather than pulp fibers. Further, in order to prevent the hot melt 31 serving as an indicator applied to the back sheet 5 from penetrating into the core wrap sheet, it is necessary to cool the back sheet 5 after applying the hot melt 31 serving as an indicator and laminate it in a sufficiently fixed state.

[0029] FIG. 4 is a diagram showing a hot melt application step according to an embodiment. The back sheet 5 flows through the manufacturing line while being applied with hot melt in the longitudinal direction on the skin side, and the core wrap sheet 9 is adhered to the skin side. Specifically, the back sheet 5 flows on the line from the upper right to the lower left in FIG. 5. On the line, an applicator 20 and an applicator 21 are arranged, and hot melt is applied onto the back sheet 5 from nozzles provided in plurality on each applicator.

[0030] The hot melt 30 applied by the applicator 20 serves as an adhesive for adhering the back sheet 5 and the absorber 6 wrapped with the core wrap sheet 9 in a subsequent step. On the other hand, the hot melt 31 applied by the applicator 21 contains a discoloring component that changes color when touched by urine and functions as an indicator. In the step shown in FIG. 4, the hot melt 31 is applied in the center of the width direction of the back sheet, parallel to the longitudinal direction. The application direction of the hot melt 30 is the same as that of the hot melt 31, but it is applied to the left and right in the width direction of the hot melt 31. As a result, the hot melt 31 is applied inside the application surface of the hot melt 30.

[0031] In the example of FIG. 4, the applicator 20 is arranged on the downstream side of the line. Therefore, the hot melt 30 comes into contact with the absorber 6 in a state where it has just been applied and has not yet solidified. On the other hand, since the applicator 21 is arranged sufficiently far upstream of the line, the hot melt 31 is sufficiently cooled and solidified on the line when it comes into contact with the absorber 6.

[0032] ​As a result, when it comes into contact with the absorber 6, the hot melt 30 soaks into the fibers of the core wrap sheet 9 and adheres the absorber 6 and Backsheet 5. However, since the hot melt 31 has already solidified at this point, it does not penetrate into the core wrap sheet 9. For this reason, even if the diaper 1 as a product is stored in an actual environment such as high temperature and high humidity and the absorber 6 absorbs moisture, the hot melt 31 does not penetrate into the core wrap sheet 9, so moisture does not move from the moisture-absorbed absorber 6 and cause discoloration.

[0033] FIG. 5 is a side view of the hot melt application process according to the embodiment. The conveyor 23 rides on a plurality of rollers 24 and moves left and right by the rotation of the rollers 24. The back sheet 5 is disposed on the conveyor 23 in a state where it has not been cut yet. An applicator 20 and an applicator 21 for applying hot melt are installed on the back sheet 5. The installation position of the applicator 21 is at a certain distance from the applicator 20.

[0034] The hot melt 30 applied by the applicator 20 serves as an adhesive for adhering the absorber 6 wrapped by the back sheet 5 and the core wrap sheet 9. Further, the hot melt 31 applied by the applicator 21 contains a discoloring component that discolors when urine touches it and functions as an indicator for notifying the diaper change timing. A cooling head 22 is provided between the applicator 20 and the applicator 21 to cool the sheet and the hot melt passing nearby. In the example of FIG. 6, the cooling head 22 is provided under the conveyor, but it may be provided above the conveyor.

[0035] The conveyor 23 moves the backsheet 5 from the right side to the left side of the drawing by the rotation of a plurality of rollers 24 with the backsheet 5 placed thereon. In this figure, the backsheet 5 first passes under the applicator 21 and the hot melt 31 is applied thereto. Next, the backsheet 5 applied with the hot melt 31 passes near the cooling head 22. At the time when the hot melt 31 is applied to the backsheet 5 from the applicator 21, the hot melt 31 at a high temperature is forcibly cooled by the cooling head 22 and solidifies.

[0036] Next, the backsheet 5 passes through the applicator 20 and the hot melt 30 is applied thereto, and then contacts the absorber 6 without delay. When contacting the absorber 6, the hot melt 30 has not yet solidified, and the hot melt 30 penetrates into the fibers of the core wrap sheet 9 that wraps the absorber 6 and eventually solidifies. In this process, the absorber 6 and the backsheet 5 are adhered by the hot melt 30. On the other hand, since the hot melt 31 has already solidified at the time when the absorber 6 is placed, the hot melt 31 does not penetrate into the fibers of the core wrap sheet 9. Therefore, the hot melt 31 does not directly contact the absorber 6, and even if the absorber 6 absorbs moisture, the hot melt 31 does not change color, so the function as an indicator can be maintained.

[0037] Note that a cooling mechanism such as the cooling head 22 is not essential. As long as the hot melt 31 is solidified when the backsheet 5 and the absorber 6 come into contact, the installation positions of the applicator 21 and the absorber 6 may be sufficiently separated or the moving speed of the conveyor may be decreased, and the hot melt 31 may be solidified by natural cooling before contact.

[0038] FIG. 6 is a diagram showing another coating process of the hot melt according to the embodiment. In the process of FIG. 7, the hot melt 31 has been previously applied to the backsheet 5 in a separate process. Since sufficient time has elapsed after the application, the hot melt 31 has been sufficiently solidified, and the cooling process can be omitted. The cooling process can be omitted.

[0039] Before the hot melt 30 for subsequent use is applied from the applicator 20 and solidifies, it contacts the absorber 6 and penetrates between the fibers of the core wrap sheet 9, so that the back sheet 5 and the absorber 6 are adhered as described in other figures.

[0040] With these configurations, the hot melt 31 constituting the indicator does not penetrate into the core wrap sheet 9 and does not directly contact the absorber 6. Therefore, even if the absorber 6 absorbs moisture due to environmental changes, it will not be affected and change color. For this reason, an exchange notification indicator that is resistant to environmental changes can be provided.

[0041] As described above, the embodiments of the features of the present invention have been described, but the content of the present invention is not limited to the above embodiments. In the above embodiments, a tape-type disposable diaper has been described, but it can also be applied to sheet-type or pant-type diapers.

[0042] Also, the place where the hot melt for adhesion is applied does not necessarily have to be the back sheet. It may be applied to the back sheet side of the core wrap sheet immediately before the absorber contacts the back sheet. Even with such a configuration, the non-solidified hot melt penetrates between the fibers of the back sheet and then solidifies, so that the back sheet and the absorber can be adhered. In the case of such a configuration, furthermore, if the hot melt serving as an indicator has already been applied to the back sheet, the applicator is not required on the back sheet side.

Explanation of Reference Numerals

[0043] 1 ·· Diaper 1B ·· Crotch Region 1F ·· Front Body Region 1R ·· Rear Body Region 2F ·· Front Patch 2L, 2R ·· Tape 3BL, 3BR ·· Three-dimensional Gather 3R ·· Waist Gather 4 ·· Cover Sheet 4KL, 4KR ·· Tuck 4C, 4SL, 4SR, 8EL, 8ER, 9ER ··· Elastic member 5 ··· Backsheet 6 ··· Absorbent body 7 ··· Topsheet 8 ··· Sidesheet 9 ··· Core wrap sheet 20, 21 ··· Applicator 22 ··· Cooling head 23 ··· Conveyor 24 ··· Roller 30, 31 ··· Hot melt

Claims

1. In the process of manufacturing an absorbent article, A second hot melt that does not contain a component whose color changes when it comes into contact with a liquid is applied to a backsheet coated with a first hot melt containing a component whose color changes when it comes into contact with a liquid and solidified, The solidified first hot melt is brought into contact with a core wrap sheet that wraps the absorbent body and is made of a moisture-non-absorbing material, and before the second hot melt solidifies, the absorbent body wrapped with the core wrap sheet is brought into contact so that the second hot melt penetrates between the fibers of the core wrap sheet, The second hot melt penetrates between the fibers of the core wrap sheet to bond the absorbent body and the backsheet, A method for manufacturing an absorbent article.

2. The first hot melt is previously applied to the backsheet and solidified, The method for manufacturing an absorbent article according to Claim 1.

3. The first hot melt is applied to the backsheet before the second hot melt is applied, and is solidified when the second hot melt is applied, The method for manufacturing an absorbent article according to Claim 1.

4. A cooling device for cooling the hot melt is provided between the application position of the first hot melt and the application position of the second hot melt, The first hot melt is cooled by the cooling device after application and before the second hot melt is applied, and is solidified when the second hot melt is applied, The method for manufacturing an absorbent article according to Claim 3.

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