WO2015166744A1

WO2015166744A1 - Composite sheet production method and composite sheet production device

Info

Publication number: WO2015166744A1
Application number: PCT/JP2015/058380
Authority: WO
Inventors: 山本　広喜; 美彦松本
Original assignee: ユニ・チャーム株式会社
Priority date: 2014-04-28
Filing date: 2015-03-19
Publication date: 2015-11-05
Also published as: JP5914566B2; JP2015208532A; TW201600070A

Abstract

A composite sheet production method that produces a composite sheet (7) that is for an absorbent article and that includes an elastic sheet (8) and a low-stretchability sheet (9) that has lower stretchability than the elastic sheet (8). The method includes: transporting the low-stretchability sheet (9) along a transport route; discharging ink droplets toward the low-stretchability sheet (9) that is transported along the transport route and printing an image on the surface of the low-stretchability sheet (9) at a prescribed location on the transport route; and, while the elastic sheet (8) is transported in a stretched state, joining the elastic sheet (8) to the low-stretchability sheet (9) at a location that is further downstream in the transport direction on the transport route than the prescribed location.

Description

Composite sheet manufacturing method and composite sheet manufacturing apparatus

The present invention relates to a composite sheet manufacturing method and a composite sheet manufacturing apparatus.

In a paper diaper as an absorbent wearing article, a pattern or a letter is attached to the outer member of the diaper in order to improve the design on the appearance or make it easy to distinguish the front and rear of the diaper. When manufacturing such a diaper, it is common to comprise a diaper using the base material sheet on which images, such as a character, were printed beforehand. For example, in Patent Document 1, a predetermined color design is printed on the entire area of an interior sheet (base material sheet) that covers the back surface of a paper diaper so that the color design can be viewed from the outside of the diaper. An invention relating to a disposable diaper capable of giving an impression like underwear is described.

JP 2003-70838 A

In recent years, as a material for producing a disposable paper diaper, a composite sheet produced by stacking and fixing a low stretch sheet on a stretch sheet stretched at a predetermined stretch ratio may be used. It is also desired to print an image on such a stretchable composite sheet and to produce a stretchable paper diaper with characters and patterns using the printed stretchable sheet. On the other hand, Patent Document 1 and the like do not disclose a specific method for printing an image on a stretchable substrate sheet. Therefore, it is required to efficiently produce a stretchable sheet on which an image having a good image quality is printed as a base material for producing a stretchable imaged paper diaper.

The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to efficiently produce a stretchable sheet on which an image having a good image quality is printed.

The main invention for achieving the above object is:
A composite sheet manufacturing method for manufacturing a composite sheet having an elastic sheet according to an absorbent article and a low extensibility sheet having lower extensibility than the elastic sheet, wherein the low extensibility sheet is used as a transport path. The ink droplets are ejected toward the low-extensible sheet transported along the transport path, and an image is formed on the surface of the low-extensible sheet at a predetermined position in the transport path. Printing and joining the stretchable sheet to the low stretchable sheet at a position downstream of the predetermined position in the transport path in the transport direction while transporting the stretchable sheet in an extended state. A composite sheet manufacturing method characterized by comprising:
Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

According to the present invention, a stretchable sheet on which an image having a good image quality is printed can be efficiently produced.

It is a schematic perspective view of the underpants type diaper 1 as an example of the absorbent article which concerns on this embodiment. It is the schematic plan view which looked at the diaper 1 of the unfolding state from the skin side. It is a schematic perspective view which decomposes | disassembles and shows the diaper 1 of an unfolding state. It is a schematic side view of the production line LM which manufactures the exterior sheet 7 which comprises the diaper 1. 1 is a schematic configuration diagram of a printing apparatus 15. FIG. It is a figure explaining arrangement of head unit 151 and nozzle Nz. It is a figure explaining the printing image which considered the part for shrinkage. It is a schematic side view showing the modification of the manufacturing line LM which manufactures the exterior sheet 7 which comprises the diaper 1. It is a figure showing about the case where the drying part 50 is provided in the production line LM.

At least the following matters will become apparent from the description of the present specification and the accompanying drawings.
A composite sheet manufacturing method for manufacturing a composite sheet having an elastic sheet according to an absorbent article and a low extensibility sheet having lower extensibility than the elastic sheet, wherein the low extensibility sheet is used as a transport path. The ink droplets are ejected toward the low-extensible sheet transported along the transport path, and an image is formed on the surface of the low-extensible sheet at a predetermined position in the transport path. Printing and joining the stretchable sheet to the low stretchable sheet at a position downstream of the predetermined position in the transport path in the transport direction while transporting the stretchable sheet in an extended state. A composite sheet manufacturing method characterized by comprising:

According to such a composite sheet manufacturing method, a stretchable sheet on which an image having a good image quality is printed can be efficiently manufactured.

In such a composite sheet manufacturing method, it is desirable that the stretchable sheet is bonded to the surface opposite to the surface on which the image is printed in the low-extension sheet.

According to such a composite sheet manufacturing method, both sheets can be joined (welded) in a state where no ink droplets are interposed between the low-extension sheet and the stretchable sheet. If there is a foreign substance such as an ink droplet on the joining surface between sheets, there is a possibility that poor welding occurs partially and the welding strength deteriorates. However, by joining the sheet member on the surface opposite to the printing surface, the possibility of such welding failure occurring can be reduced. Thereby, it becomes easy to form a joint (welded part) having sufficient strength.

In such a composite sheet manufacturing method, the low-extension sheet and the stretchable sheet can be joined to each other by a horn having a vibration surface that vibrates ultrasonically, and a rotatable outer surface that receives vibration from the vibration surface. Using the roller part, it is performed by injecting ultrasonic vibration from the horn part to the low-extensible sheet and the stretchable sheet superimposed on each other on the outer peripheral surface of the roller part, It is desirable.

According to such a composite sheet manufacturing method, it is possible to perform ultrasonic welding while winding the low stretchable sheet and the stretchable sheet on the outer peripheral surface of the roller portion in a state of being overlapped and transporting without relative slip. This facilitates accurate and reliable welding.

In this composite sheet manufacturing method, the stretchable sheet is predetermined based on a difference between a peripheral speed when the roller portion rotates and a peripheral speed when a nip roll that conveys the stretchable sheet rotates. It is desirable that the sheet is transported in a stretched state up to the stretching magnification.

According to such a composite sheet manufacturing method, the elastic sheet is conveyed in an expanded state by adjusting the rotation speed of the elastic sheet conveying mechanism (nip roll) and the roller portion (anvil roller) provided in the welding apparatus. The stretching magnification at the time of setting can be set to an arbitrary value, and the low-stretch sheet and the stretch sheet can be welded and joined in that state.

In such a composite sheet manufacturing method, when the low-stretch sheet and the stretchable sheet are joined, the low-stretch sheet is disposed on the roller part side, and the stretchable part is on the horn part side. It is desirable that the adhesive sheet is disposed.

According to such a composite sheet manufacturing method, it is possible to perform welding without bringing the low-extension sheet having an image printed on the surface thereof into contact with the horn portion of the welding apparatus. As a result, ink droplets (ink) are prevented from adhering to the vibration surface of the horn unit, occurrence of poor welding, an increase in the number of maintenances of the horn unit, and the ink adhering to the horn unit are transferred to the substrate side. Can be prevented from occurring.

In such a composite sheet manufacturing method, it is desirable that the stretchable sheet has a structure having a plurality of fibers entangled with each other so as to have a denseness and a plurality of voids formed between the fibers.

According to such a composite sheet manufacturing method, a higher quality image can be printed. For example, when ink droplets are ejected onto a dense and dense elastic sheet, the ink droplets penetrate between fibers or penetrate voids, making it difficult to land on the correct position, resulting in a deterioration in the quality of the printed image. There is a risk. For this reason, printing on a low-stretch sheet without coarseness (less coarseness) is performed after printing on a stretchable sheet with coarseness and then joining with the low-stretchability sheet. When this is done, it is easier to print a higher quality image.

In such a composite sheet manufacturing method, it is desirable to dry the image printed on the low-extensible sheet between the time when the printing is performed and the time when the bonding is performed.

According to such a composite sheet manufacturing method, by drying the ink on the surface of the low-extension sheet, the image is quickly fixed on the surface of the sheet, and the image is hardly deteriorated. In addition, since the ink component on the sheet surface is difficult to move to other elements (for example, a conveyance roller), the handling of the low-extensible sheet (composite sheet) is improved in the steps after the drying step.

Moreover, it is a composite sheet manufacturing apparatus for manufacturing a composite sheet having a stretchable sheet according to an absorbent article and a low stretchable sheet having a stretchability lower than that of the stretchable sheet, and transports the low stretchable sheet. A surface of the low stretch sheet at a predetermined position of the transport path by discharging ink droplets toward the transport section transported along the path and the low stretch sheet transported along the transport path; The stretchable sheet is printed on the low stretchable sheet at a position downstream of the predetermined position in the transport path with respect to the transport direction while transporting the stretchable sheet in an expanded state. The composite sheet manufacturing apparatus including the joining portion to be joined becomes clear.

According to such a composite sheet manufacturing apparatus, it is possible to efficiently manufacture a stretchable sheet on which a good quality image is printed.

=== Embodiment ===
The composite sheet according to the absorbent article of the present embodiment is used in a production line LM for a pants-type disposable diaper 1 (hereinafter also simply referred to as diaper 1) as an example of an absorbent article.

<Basic structure of diaper 1>
FIG. 1 is a schematic perspective view of a pant-type diaper 1. FIG. 2 is a schematic plan view of the unfolded diaper 1 as seen from the skin side. FIG. 3 is a schematic perspective view showing the exploded diaper 1 in an exploded state.

In the following description, when the diaper 1 is attached to the wearer, the side that should be located on the skin side of the wearer is simply referred to as “skin side”, and on the other hand, on the non-skin side of the wearer. The side to be positioned is simply referred to as the “non-skin side”.

As shown in FIGS. 2 and 3, the diaper 1 is, for example, a two-piece type diaper. That is, the diaper 1 has, as a first part, an absorbent main body 3 having a substantially rectangular shape in plan view that absorbs excretory fluid such as urine, and is provided to cover the non-skin side surface of the absorbent main body 3. The outer sheet 7 having a substantially hourglass shape in plan view that forms the outer casing of the diaper 1 is provided as the second component.

As shown in FIG. 3, the absorbent main body 3 has an absorbent core 3c that absorbs excretory fluid. The absorbent core 3c is formed by molding liquid absorbent fibers such as pulp fibers and liquid absorbent granular materials such as superabsorbent polymers into a substantially rectangular shape in plan view as an example of a predetermined shape. In addition, this absorptive core 3c may be coat | covered with liquid-permeable coating sheets, such as tissue paper, as needed.

The skin side surface of the absorbent core 3c is provided with a liquid-permeable top sheet 4 such as a nonwoven fabric so as to cover the surface. Similarly, the non-skin side surface of the absorbent core 3c has the surface A liquid-impermeable leak-proof sheet 5 such as a film is provided so as to cover the entire surface.

Although not shown, thread rubber as an elastic member may be provided along the longitudinal direction of the main body 3 at both ends of the absorbent main body 3 in the width direction. Such a rubber thread imparts stretchability to the vicinity of the leg opening HL in the absorbent main body 3 and the exterior sheet 7. Therefore, such a rubber thread is, for example, an adhesive such as a hot melt adhesive while being inserted between the top sheet 4 and the leak-proof sheet 5 and extended from a natural length to a predetermined magnification such as 2 to 4 times. To be fixed to both

sheets

4 and 5.

In some cases, a leak-proof wall (not shown) may be provided in the absorbent main body 3 for the purpose of preventing side leakage of urine. Such a leak-proof wall portion is also called a three-dimensional gather, and is provided so as to stand at both end portions such as the skin side surface of the absorbent main body 3 using a flexible sheet such as a nonwoven fabric as a material. However, this leak-proof wall part is a well-known structure. Therefore, further explanation is omitted.

The exterior sheet 7 is a flexible sheet having a substantially hourglass shape in plan view in the unfolded state of FIG. 2, and the sheet 7 has a thickness direction, a longitudinal direction, and a width direction as three directions orthogonal to each other. ing. The exterior sheet 7 is divided into three

portions

7f, 7b, and 7c with respect to the longitudinal direction. That is, the exterior sheet 7 is formed on an abdominal side portion 7f disposed on the wearer's belly side, a back side portion 7b disposed on the wearer's back side, and a crotch portion 7c disposed on the wearer's crotch. It is divided. Of course, the crotch part 7c is located between the abdomen side part 7f and the dorsal side part 7b, so that the crotch part 7c has a shape that is constricted in the width direction in a substantially hourglass shape in plan view. This is part 7c.

As shown in FIG. 3, a so-called laminate sheet 7 having a two-layer structure is used for the exterior sheet 7. That is, the exterior sheet 7 is a composite sheet having an inner layer sheet 8 that forms an inner layer facing the wearer's skin when the diaper 1 is worn, and an outer layer sheet 9 that forms an outer layer facing the non-skin side when the diaper 1 is worn. is there. The inner layer sheet 8 and the outer layer sheet 9 are bonded together by adhesion or welding while being overlapped in the thickness direction. In this example, the bonded portions, which are bonded portions, are welded in a predetermined bonding pattern (not shown) formed by discontinuous dispersion.

As the material of the inner layer sheet 8, a stretchable sheet 8 having stretchability in the width direction of the diaper 1 is used. On the other hand, the material of the outer layer sheet 9 has a low extensibility in the width direction of the diaper 1. A low stretch sheet 9 is used. The stretchable inner layer sheet 8 is stretched to a predetermined stretch ratio such as 2.5 times the natural length in the width direction (hereinafter also referred to as the stretched state), and is also stretched in the width direction. Overlaid on the low-extension outer layer sheet 9, both the sheets 8 and 9 are fixed integrally with the above-mentioned joining pattern.

Therefore, when the stretched state is released, the inner layer sheet 8 shrinks in the width direction of the diaper 1 based on its own stretchability. At this time, the low stretchable outer layer sheet 9 has a plurality of hooks. The diaper 1 bends in the width direction, whereby the outer layer sheet 9 quickly follows the contraction of the inner layer sheet 8 and shortens the entire length in the width direction. As a result, in an unloaded state where no external force acts on the diaper 1, the outer sheet 7 is shortened in the width direction as a whole, and the outer surface of the outer sheet 7 is caused by the bending of the outer layer sheet 9. It is in a state where several traps are approaching. However, when an external force is applied to the exterior sheet 7 in the width direction, the exterior sheet 7 can be stretched approximately elastically until the wrinkle is fully extended, whereby the exterior sheet 7 of the diaper 1 It has become a specification with elasticity.

Incidentally, the term “stretchability” as used herein refers to the property that when an external force of tension is applied, it stretches approximately elastically in the direction of the external force and contracts approximately elastically when the external force is released. is there. Moreover, although it repeats, the sheet | seat which has this elasticity is said "elastic sheet 8".

Note that the stretchable sheet 8 desirably satisfies the following conditions. That is, in the state where both ends in the longitudinal direction of the belt-like sheet having a short dimension of 25 mm are equally gripped with the total length of 25 mm in the short direction, the both ends are each 1.0 (N) as a power point. The elongation (%) when pulled in the longitudinal direction by an external force is an arbitrary value in the range of 50% to 300%, and the residual elongation strain (%) that remains without contracting after the external force is released and contracted However, it is preferable that the value is an arbitrary value in the range of 0% to 40%. More preferably, the elongation rate is an arbitrary value in the range of 70% to 200%, and the residual elongation strain is an arbitrary value in the range of 0% to 30%. Incidentally, the above-mentioned elongation rate (%) is the natural length L0, which is the length of the belt-like sheet at the time of no load before being pulled, from the length L1 of the belt-like sheet when pulled with an external force of 1.0 (N). Is a percentage notation value of a division value (= ΔL1 / L0) obtained by dividing a subtraction value ΔL1 (= L1−L0) obtained by subtracting by the natural length L0. The residual elongation strain (%) is a subtracted value ΔL2 (= L2) obtained by subtracting the natural length L0 before pulling from the length L2 after releasing the external force of 1.0 (N). -L0) is a percentage of the division value (= ΔL2 / ΔL1) obtained by dividing the natural length L0 by the subtraction value ΔL1 (= L1−L0) obtained by subtracting the natural length L0 from the length L1 when pulled by the external force. It is a written value.

Further, the “low stretch sheet 9” is a stretch sheet lower than the stretch sheet 8 described above. That is, the stretch rate (%) when an external force of a predetermined amount of tension is applied is lower than the stretch rate (%) of the stretchable sheet 8 described above. Note that the low-extensible sheet 9 desirably satisfies the following conditions. That is, in the state where both ends in the longitudinal direction of the belt-like sheet having a short dimension of 25 mm are equally gripped with the total length of 25 mm in the short direction, the both ends are each 1.0 (N) as a power point. The elongation (%) when pulled in the longitudinal direction by an external force is preferably an arbitrary value in the range of 0% to 20%. More preferably, the elongation rate is an arbitrary value in the range of 0% to 10%.

In addition, as a form of the stretchable sheet 8 and the low stretchable sheet 9, a non-woven fabric, a woven fabric, or a film may be used.

About the specific example of the nonwoven fabric which can be utilized for the elastic sheet 8, it is appropriate to perform a gear stretching process or the like on a nonwoven fabric having a thermoplastic elastomer fiber exhibiting substantially elasticity and a thermoplastic resin fiber exhibiting substantially inelasticity. Examples of the nonwoven fabric subjected to various stretching treatments. That is, by performing such stretching treatment, if the substantially inelastic thermoplastic resin fibers contained in the nonwoven fabric are plastically deformed or the joints between the fibers are destroyed, the substantially elastic fibers of the thermoplastic elastomer fibers can be obtained. The nonwoven fabric can be changed to a structure that hardly inhibits elastic deformation, whereby the stretchability of the nonwoven fabric is expressed and the stretchable sheet 8 can be used.

Examples of the substantially elastic thermoplastic elastomer include polyurethane elastomers, polystyrene elastomers, polyolefin elastomers, polyamide elastomers, and the like. Examples of substantially inelastic thermoplastic resin fibers include fibers containing polyolefin resins, and examples of polyolefin resins include polyethylene (PE), polypropylene (PP), and ethylene-α olefin copolymers. Can be illustrated. By the way, in this example, the stretchable sheet 8 is obtained by subjecting a mixed fiber type nonwoven fabric having polyurethane-based elastomer fibers and PP fibers to gear stretching treatment.

In addition, since such a stretchable sheet 8 is configured in a state where a plurality of fibers are randomly intertwined, when viewed microscopically, the stretchable sheet 8 has a structure having a plurality of voids between the fibers. ing. And on the surface, there are a portion where the fibers are intertwined closely and a portion where the fibers are intertwined roughly. In other words, the stretchable sheet 8 has a structure having a density. Therefore, even when both ends of the elastic sheet 8 are gripped equally in the lateral direction and pulled in the longitudinal direction, the entire region in the lateral direction does not extend evenly, and is partially dense. Becomes larger, and a portion where the gap becomes larger is generated.

Specific examples of the nonwoven fabric that can be used for the low-extension sheet 9 include spunbond nonwoven fabric, meltblown nonwoven fabric, spunbond nonwoven fabric, meltblown nonwoven fabric, and spunbond nonwoven fabric made of fibers such as PE, PP, polyester, and polyamide. The so-called SMS nonwoven fabric, air-through nonwoven fabric and the like can be exemplified. The fiber structure is not limited to a single fiber made of a single thermoplastic resin as described above. For example, a composite fiber having a core-sheath structure in which the core material is PP and the sheath material is PE may be used, or a fiber having a structure other than these may be used. Incidentally, in this example, a spunbonded nonwoven fabric of PP fibers is used as the low stretch sheet 9.

As shown in FIGS. 2 and 3, the absorptive main body 3 described above is in the longitudinal direction of the skin side surface of the exterior sheet 7 having such a two-layer structure, that is, on the skin side surface of the inner layer sheet 8. It is attached with the direction aligned. Such attachment is made by joining at least the

end portions

3e, 3e in the longitudinal direction of the absorbent main body 3 to the exterior sheet 7, and in this example, as shown in FIG. 3, the

end portions

3e, 3e. Are formed in a substantially T-shape with joint portions j and j for joining the absorbent main body 3 and the exterior sheet 7, respectively. That is, each joint j, j extends toward the crotch part 7c starting from the laterally long strip portion jW that is long in the width direction of the diaper 1 and the central portion in the lateral direction of the lateral strip portion jW. And a vertically long belt-like portion jL. And this effectively avoids that the absorptive main body 3 and the exterior sheet 7 restrain each other more than necessary. However, the shape of the joint j is not limited to this. For example, a dotted joint jC may be additionally provided at a position between the pair of T-shaped joints j, j, or the

ends

3e and 3e of the absorbent main body 3 may be abbreviated. A joint portion (not shown) having a substantially rectangular shape extending over the entire area may be formed at each of the

end portions

3e and 3e, or a joint portion having a shape other than the shape described above may be formed. . Furthermore, in this example, the formation of the joint j is realized by adhesion of a hot melt adhesive, but is not limited to this, and may be, for example, welding.

Moreover, in this example, attachment of this absorptive main body 3 and the exterior sheet 7 is the expansion | extension state of the width direction of the exterior sheet 7, and the inner layer sheet 8 at the time of fixing the above-mentioned outer layer sheet 9 and the inner layer sheet 8 is fixed. It is made in an extended state that is more relaxed than the extended state. As a result, wrinkles that can occur in the absorbent main body 3 when it finally becomes the pant-type diaper 1 are reduced, and as a result, the liquid absorbency decrease and urine of the absorbent main body 3 described above are reduced. Leakage can be effectively suppressed.

And the exterior sheet | seat 7 to which the absorptive main body 3 was attached like FIG. 2 is folded in half by the crotch part 7c, and the abdominal side part 7f and the back side part 7b are piled up. Then, in this overlapped state, the abdomen side portion 7f and the back side portion 7b are joined at the respective end portions 7eW in the width direction, so that the waist opening HB as shown in FIG. It is made into the form of the underpants type diaper 1 in which the leg periphery opening parts HL and HL were formed.

In the pants-type diaper 1 of the present embodiment, an image G composed of predetermined characters, patterns, characters, etc. is printed on the exterior sheet 7 (see FIG. 1). The image G improves the design on the appearance of the diaper 1 and allows the user to visually recognize information about the diaper 1 (for example, information indicating the product name and the front and back of the diaper 1). . Below, the method to manufacture the composite sheet (exterior sheet 7) which has the elastic sheet 8 and the low extensibility sheet 9 is demonstrated, printing such an image.

<Method for manufacturing exterior sheet>
FIG. 4 is a schematic side view of a production line LM for producing the exterior sheet 7 constituting the diaper 1. The production line LM uses the stretchable sheet 8 and the low extensibility sheet 9 as materials to generate a continuous sheet 7a in which the exterior sheet 7 is continuous in the width direction (hereinafter also simply referred to as the exterior sheet 7a). The manufacturing line LM includes a transport mechanism CV, a printing unit 10, and a joining unit 20. The exterior sheet 7a is manufactured by performing various processes described later by these mechanisms.

The transport mechanism CV is a transport unit that transports the stretchable sheet 8 and / or the low-extensible sheet 9 continuously along a predetermined transport path. As the transport mechanism CV, for example, a transport roller, a suction belt conveyor having a suction holding function on a belt surface as a placement surface, or the like is used. In the transport mechanism CV of the present embodiment, the low-extensible sheet 9 as the outer layer sheet 9 is transported in a so-called lateral flow mode. That is, the continuous sheet 9a of the low-extensible sheet 9 is conveyed in a state where portions corresponding to the diaper 1 are arranged in a line in the conveyance direction while aligning the direction corresponding to the width direction of the diaper 1 in the conveyance direction. In the following description, the continuous sheet 9a of the low stretch sheet 9 that is the outer layer sheet 9 is referred to as a low stretch continuous sheet 9a. Similarly, the stretchable sheet 8 which is the inner layer sheet 8 is also conveyed in a so-called lateral flow mode, and the portions corresponding to the diaper 1 are aligned in a line in the conveying direction while aligning the direction corresponding to the width direction of the diaper 1 with the conveying direction. Thus, the continuous sheet 8a of the stretchable sheet 8 is conveyed. Hereinafter, the continuous sheet 8a of the stretchable sheet 8 which is the inner layer sheet 8 is referred to as a stretchable continuous sheet 8a.

In the following description, the above-described transport direction set on the production line LM is also referred to as “MD direction”. One of the two directions orthogonal to the MD direction is referred to as “CD direction”, and the other is referred to as “Z direction”. The CD direction is parallel to the width direction of the exterior sheet 7a, and in FIG. The Z direction is parallel to the thickness direction of the exterior sheet 7a.

(Printing process)
In the production line LM, first, a printing process is performed in which an image is printed using the printing unit 10 on the low-extension continuous sheet 9a conveyed along the MD direction (conveyance direction). The printing unit 10 includes a transport mechanism 11 and a printing device 15.

The transport mechanism 11 is, for example, a transport roller 11R that rotates around a rotation axis along the CD direction.
Is the main body. Then, the low-stretch continuous sheet 9a fed from the original roll disposed on the upstream side in the MD direction is sent out to the printing apparatus 15 while being conveyed at a predetermined conveyance speed along the MD direction. The transport roller 11R rotates at a predetermined peripheral speed V11R (m / min), thereby transporting the low-extension continuous sheet 9a along the MD direction at a transport speed V11 (m / min). The conveyance speed V11 (m / min) is a speed at which the low-extension continuous sheet 9a can be conveyed in a state where the low-extension continuous sheet 9a is properly stretched so as not to be plastically deformed. That is, the low stretchable continuous sheet 9a transported by the transport mechanism 11 is in a so-called non-stretching state in which it is difficult to stretch any more, and is in a state in which slackening is unlikely to occur. By the way, if such a “non-stretched state” is defined, for example, “the sheet is not damaged, and further, the sheet is kept in a state of being stretched further by 5% or more from the current state. It can be said that the state does not expand.

The printing apparatus 15 discharges liquid (for example, ink) from the Z direction to the low stretchable continuous sheet 9a conveyed in the MD direction, thereby forming an image on the surface of the low stretchable continuous sheet 9a. A general inkjet printer (particularly a line printer) or the like can be used. FIG. 5 is a schematic configuration diagram of the printing apparatus 15. The printing apparatus 15 according to the present embodiment includes a head unit 151, an ink tank 152, and a controller 153.

The head unit 151 is for ejecting ink onto a printing medium (low-extensible continuous sheet 9a in the present embodiment), and a plurality of head units 151 are provided for each color of ejected ink. For example, a black head unit 151K that discharges black (K) ink, a cyan head unit 151C that discharges cyan (C) ink, a magenta head unit 151M that discharges magenta (M) ink, and a yellow (Y ), The four head units 151 of the yellow head unit 151Y for discharging ink are arranged side by side along the MD direction. These head units 151 are arranged at positions facing the low stretch continuous sheet 9a to be conveyed, and each has a head having a plurality of nozzles Nz. FIG. 6 is a diagram illustrating the arrangement of the head unit 151 and the nozzles Nz. In FIG. 6, for example, a black head unit 151K has four heads 151K1 to 151K4. In each of the heads 151K1 to 151K4, a nozzle row in which a plurality of nozzles Nz are arranged at a predetermined interval (pitch) D is formed. Then, as shown in FIG. 6, the heads 151K1 to 151K4 are arranged in a staggered pattern with respect to the CD direction, so that the black head unit 151K can eject ink along the CD direction. As shown in FIG. 6, the lengths of the heads 151K1 to 151K4 arranged in the CD direction are set longer than the CD direction length of the printing medium (that is, the width of the low-extensible continuous sheet 9a), thereby printing the printing medium. Ink can be discharged over the entire area. The basic configuration is the same for the

other head units

151C, 151M, and 151Y. Further, instead of one head unit 151 corresponding to one color ink, one head unit 151 may correspond to a plurality of colors of ink. For example, a head provided in a certain head unit 151 may include two nozzle rows and eject different colors of ink from each nozzle row.

The nozzles Nz are ejection ports for ejecting ink, and each nozzle Nz is provided with a piezoelectric element (not shown) correspondingly. The piezoelectric element expands and contracts when a drive signal generated by the controller 153 is applied. A pressure chamber (not shown) communicating with each nozzle is provided inside the head, and the ink supplied from the ink tank 152 is filled in the pressure chamber. Then, when the pressure in the pressure chamber rises and falls due to the expansion and contraction of the piezoelectric element, the ink filled in the pressure chamber is intermittently ejected so as to be pushed out from each nozzle Nz. The ejected ink becomes substantially spherical ink droplets (ink dots) while flying in the atmosphere, and lands on the low-extension continuous sheet 9a that is a printing medium conveyed in the MD direction. An image is formed on the low stretchable continuous sheet 9a by arranging a large number of landed ink droplets in the MD direction and the CD direction.

Note that the ejection method used when ejecting ink from the head unit 151 is not limited to the method using the piezoelectric element as described above. For example, a head unit 151 that employs a so-called thermal head system, which discharges ink by generating air bubbles by heating ink in a pressure chamber instead of a piezoelectric element, and other ejection systems are employed. The head unit 151 may be used.

The ink tank 152 is an ink storage unit that stores ink used for printing, and is provided for each color. In the present embodiment, ink tanks 152 for KCMY four colors are provided for each of the

head units

151K, 151C, 151M, and 151Y, and ink is supplied to pressure chambers provided in the heads. The types of ink colors used for printing are not limited to the four colors KCMY, and other colors may be used depending on the type of image to be printed. For example, an image may be printed using light cyan (LC) or white (W) ink.

The controller 153 is a control unit that controls the operation of the printing process by the printing apparatus 15. When the controller 153 receives the print start command, the controller 153 generates a drive signal for driving the head unit 151 based on the image data (print data) to be printed, and ink from the nozzle group provided in each head. To discharge. Specifically, a signal indicating the timing of ejecting ink from each nozzle Nz and the amount of ink to be ejected (size of ink droplet) is generated, and applied to the piezoelectric element described above to drive. Further, the controller 153 may control the conveyance speed V11 (m / min) of the low stretchable continuous sheet 9a by the conveyance mechanism 11. Since the timing at which ink is intermittently ejected from each nozzle Nz is determined according to the conveyance speed V11 of the low-extension continuous sheet 9a, the controller 153 itself has the conveyance speed V11 of the low-extension continuous sheet 9a and the ink ejection timing. By controlling this, it is difficult for ink droplets to land and the like, and an image with good image quality can be printed.

Also, print data for printing an image may be created by an external computer or the like, or may be created by the controller 153. The print data includes pixel data indicating the amount of ink to be ejected for each pixel, which is the minimum unit constituting an image, and an ink droplet of each color is ejected for each pixel according to the pixel data. It is formed. In the present embodiment, the appearance of the color of the landed ink droplets changes depending on the color of the low-extension continuous sheet 9a, which is a printing medium, the density of the fibers constituting the sheet, and the texture and impression of the printed image change. Therefore, it is desirable to create print data in which the ink discharge amount is appropriately corrected according to the state of the low-extension continuous sheet 9a. For this reason, the controller 153 itself creates appropriate print data and performs comprehensive control in accordance with the ink ejection and transport speed, thereby making it easier to print a higher quality image.

In the production line LM of the present embodiment, after the printing process is performed, the stretchable sheet 8 and the low stretchable sheet 9 that are stretched in the MD direction are pasted together in the downstream area in the MD direction. Thereafter, when the tensile force is released, the low stretch sheet 9 contracts in the MD direction as the stretchable stretch sheet 8 contracts in the MD direction. Therefore, the image printed on the low extensible sheet 9 also contracts in the MD direction as the elastic sheet 8 contracts. Therefore, in this print processing step, an image is printed in consideration of such shrinkage. FIG. 7 is a diagram for explaining a print image in consideration of the shrinkage. FIG. 7A shows the final image state after shrinkage, and FIG. 7B shows the state of the image actually printed on the low stretch sheet 9. When it is desired to display the image G as shown in FIG. 1A on the diaper 1, the image G needs to be in the state shown in FIG. 7A when the exterior sheet 7 contracts. Therefore, when printing the image G on the low stretchable continuous sheet 9a before shrinkage, it is necessary to stretch the image G at the same stretch magnification in accordance with the stretch magnification of the stretchable sheet 8. That is, a process for extending the print data of the image in the state of FIG. 7A in the MD direction is performed, and the print is executed after the print data of the image in the state of FIG. 7B is generated. For example, when the expansion ratio of the stretchable sheet 8 is 1.5 times, print data of an image (state of FIG. 7B) obtained by extending the image to be printed (state of FIG. 7A) by 1.5 times in the MD direction Printing is performed using. The generation of the print data extended in the MD direction may be performed at the timing of executing printing by the controller 153, or the data extended in the MD direction by an external computer or the like is generated in advance and then the data is transmitted to the controller 153. You may do it.

In such a printing process using the production line LM, it is easy to form a good image by performing printing using the low-extension continuous sheet 9a having a low elongation rate as a printing medium. If printing is performed using the stretchable sheet 8 as a printing medium, the stretchable sheet 8 expands during transportation, and a gap (gap) between fibers constituting the stretchable sheet 8 is widened. It becomes difficult to land at an accurate position. For example, ink droplets that are driven into the gap (gap) between the fibers by the elastic sheet 8 pass through the gap and penetrate into the elastic sheet 8, or penetrate between the fibers to form the elastic sheet 8. You may not land. As a result, the landing positions of the ink droplets are displaced, and as a result, the image quality of the printed image may be deteriorated. Furthermore, since the elastic sheet 8 has a structure having roughness as described above, when such a sheet is stretched, the surface roughness tends to increase and the deviation of the landing positions of the ink droplets tends to increase. On the other hand, since the low stretch sheet 9 is conveyed in a non-stretched state, the gap between the fibers is small even if there is some roughness, and the surface is kept uniform compared to the stretch sheet 8. It is easy to sag. Accordingly, deviation of the landing positions of the ink droplets hardly occurs, and an image with good image quality can be easily formed according to the print data.

Further, the low-extensible sheet 9 is fed out from the raw roll, and after the image is printed by the printing unit 10, the low-extensible sheet 9 is joined to the stretchable sheet 8 on the same conveying line and processed as it is as the diaper 1. Therefore, after winding the printed substrate into a roll, there is no need to move it to the diaper production line again, and the printed surface is rubbed and printed when winding the substrate. It is possible to suppress the occurrence of problems such as deterioration.

(Joining process)
As shown in FIG. 4, the low-stretch continuous sheet 9 a on which printing has been performed is transported in the MD direction as it is, and joined to the stretchable continuous sheet 8 a by the joint portion 20 disposed downstream in the MD direction of the printing unit 10. By doing so, a continuous sheet of the exterior sheet 7 (exterior sheet 7a) is generated. In the present embodiment, the stretchable continuous sheet 8a is stretched in the MD direction from a substantially natural length state to a predetermined stretch magnification with respect to the low stretchable continuous sheet 9a conveyed in a stretched state along the MD direction. However, they are overlapped and joined from the thickness direction.

In order to perform the generation process of the exterior sheet 7a, the joining portion 20 includes a transport mechanism 21 for the stretchable continuous sheet 8a, a transport mechanism 22 for the low stretchable continuous sheet 9a, and an ultrasonic welding device 25. ing.

The conveyance mechanism 21 of the stretchable continuous sheet 8a has, for example, a nip roll mechanism as a main body. That is, the mechanism 21 has a pair of nip rolls 21R and 21R that rotate about a rotation axis along the CD direction. The stretchable continuous sheet 8a continuously conveyed from the upstream side is driven and rotated while the pair of nip rolls 21R and 21R are sandwiched between the outer peripheral surfaces of each other, whereby the stretchable continuous sheet 8a is transferred to the ultrasonic welding apparatus 25. Send it out.

On the other hand, the transport mechanism 22 of the low-extension continuous sheet 9a has, for example, a transport roller 22R that rotates around a rotation axis along the CD direction as a main body. Then, the conveyance roller 22R is driven to rotate while contacting the low-extension continuous sheet 9a continuously conveyed from the upstream printing unit 10 on the outer peripheral surface, whereby the low-extension continuous sheet 9a is ultrasonically welded. Send to 25.

The ultrasonic welding device 25 includes a horn 25h having a vibration surface that vibrates ultrasonically, and an anvil roller 25a that receives the ultrasonic vibration of the vibration surface of the horn 25h on the outer peripheral surface. The anvil roller 25a is supported so as to be rotatable about a rotation axis along the CD direction, and is driven to rotate by being applied with a driving force from a servo motor (not shown) as a driving source. Further, the stretchable continuous sheet 8a sent from the transport mechanism 21 is wound around the outer peripheral surface of the anvil roller 25a at a predetermined winding angle such as 45 ° or more with no relative slip with respect to the outer peripheral surface.

Therefore, when the anvil roller 25a is driven to rotate, both the stretchable continuous sheet 8a and the low stretchable continuous sheet 9a are substantially the same as the peripheral speed value V25a of the anvil roller 25a. It is conveyed along the outer peripheral surface. When the stretchable continuous sheet 8a and the low stretchable continuous sheet 9a are superposed on each other in the thickness direction on the outer peripheral surface of the anvil roller 25a, these sheets 8a are passed through the arrangement position of the horn 25h. , 9a is supplied with ultrasonic vibration energy from the vibration surface of the horn 25h, and generates heat and melts. As a result, the two

sheets

8a and 9a are joined in a joint pattern in which a plurality of joints are discontinuously dispersed as described above. Thus, the exterior sheet 7a is generated. Then, the exterior sheet 7a is sent out downstream in the MD direction by the anvil roller 25a, whereby the delivered exterior sheet 7a is transported to the downstream side in the MD direction at a conveyance speed value substantially equal to the peripheral speed value V25a. And conveyed

Here, the peripheral speed value V21R (m / min) of the nip roll 21R related to the transport mechanism 21 of the stretchable continuous sheet 8a is the transport speed of the stretchable continuous sheet 8a transported in a substantially natural length state from the upstream side. It is almost the same value (m / min). On the other hand, the peripheral speed value V25a (m / min) of the anvil roller 25a downstream thereof is set to a value of the expansion magnification times the peripheral speed value V21R (m / min) of the nip roll 21R. Therefore, when the stretchable continuous sheet 8a passes between the nip roll 21R and the anvil roller 25a, the stretchable continuous sheet 8a is stretched from the substantially natural length state to the length of the above-described stretch magnification. And it passes the position of the horn 25h in this extended state. On the other hand, regarding the peripheral speed value V22R (m / min) of the transport roller 22R related to the transport mechanism 22 of the low-extension continuous sheet 9a, the transport speed value V11R (m / min) of the low-extension continuous sheet 9a transported from the upstream side. Min) and the conveyance speed value (m / min) is substantially the same as the peripheral speed value V25a (m / min) of the anvil roller 25a. Therefore, the low-stretch continuous sheet 9a is maintained in a properly stretched state so as not to be plastically deformed. Then, the stretched low-stretch continuous sheet 9a is superposed on and joined to the stretchable continuous sheet 8a stretched to the length of the stretch magnification.

In the present specification, the term “stretch ratio” indicates how many times the total length of the stretchable continuous sheet 8a is stretched to the natural length before stretching, and the stretch ratio is It defines how much the exterior sheet 7 (7a) in the completed diaper 1 can be extended in the width direction from the unloaded state. That is, in the diaper 1 manufactured by setting the stretchable continuous sheet 8a to a predetermined stretch ratio, the exterior sheet 7 (7a) extends in the width direction of the diaper 1 until the stretched state corresponds to the stretch ratio. be able to. The expansion magnification is set to an arbitrary value in the range of 1.5 to 4 times, for example, and in this example, the expansion magnification is set to 2.5 times.

In addition, as shown in FIG. 4, in this embodiment, after printing is performed on the upper surface side in the Z direction of the low-stretch continuous sheet 9a, the stretchable continuous sheet 8a is formed on the lower surface side in the Z direction of the low-stretch continuous sheet 9a. Are joined. That is, in the low stretchable continuous sheet 9a, the stretchable continuous sheet 8a is joined to the surface opposite to the surface on which the image is printed. This is to keep the bonding strength between the low stretchable continuous sheet 9a and the stretchable continuous sheet 8a stronger. When bonding is performed using the ultrasonic welding device 25, the bonded portion is formed in a state where both the

sheets

8a and 9a are in contact with each other. At this time, if ink droplets are interposed between the both

sheets

8a and 9a, the ink There is a possibility that the droplets become foreign matters and hinder the generation of sufficient frictional heat between the sheets. That is, in the welded portions of both

sheets

8a and 9a, the melting is partially insufficient, which may cause poor welding. On the other hand, in the production line LM of this embodiment, foreign materials such as ink droplets are included between the sheets by joining the stretchable continuous sheet 8a to the surface opposite to the printing surface of the low stretchable continuous sheet 9a. Since the structure is difficult to be welded and poorly welded, it is possible to form a joint portion having sufficient strength.

By the above processes, the exterior sheet 7a in which the low-extension continuous sheet 9a on which the printing has been performed and the stretchable continuous sheet 8a in the stretched state are joined is manufactured. The manufactured exterior sheet 7a is conveyed in the MD direction as it is, and various processes such as punching and attachment of parts are performed on the exterior sheet 7a in the downstream area in the MD direction. For example, a process of punching out the leg opening HL using a die cutter device (not shown) and a process of attaching the absorbent main body 3 using an attachment device (not shown) are performed. And whenever such various processes are performed, the exterior sheet 7a changes a state sequentially, and the diaper 1 of the state of FIG. 1 is finally manufactured.

Thus, according to the production line LM of the present embodiment, an image with good image quality can be obtained by printing an image on the low extensible sheet side having a small elongation rate and then joining the stretched elastic sheet. A printed stretchable sheet can be produced. Furthermore, in the production line LM of the present embodiment, the printing process and the sheet joining process can be sequentially performed on the same line, and the exterior sheet of the diaper 1 can be efficiently manufactured.

<Modification>
As a modification of the above-described embodiment, an example in which the arrangement of the stretchable continuous sheet 8a and the low stretchable continuous sheet 9a when performing the joining process is different will be described. FIG. 8 is a schematic side view showing a modification of the production line LM for producing the exterior sheet 7 constituting the diaper 1. In the modification, a part of the configuration of the transport mechanism CV and the joint 20 is different from the production line LM in the above-described embodiment. The configuration of the printing unit 10 is almost the same as that in the above-described embodiment.

In the transport mechanism CV of the modified example, a reversing roller CVR is provided between the printing unit 10 and the joining unit 20 in the transport path so as to reverse the transport direction of the low-extension continuous sheet 9a while reversing the top and bottom in the Z direction. . In FIG. 8, the low stretchable continuous sheet 9 a is printed with an image on the upper surface side in the Z direction by the printing unit 10. That is, at the stage where the printing process is performed, the surface on which the image is printed (printing surface) faces upward in the Z direction. Thereafter, the low-extension continuous sheet 9a is reversed by the reversing roller CVR provided on the downstream side of the printing unit 10 so that the printing surface faces downward in the Z direction. And it is conveyed in the state stretched along MD direction by the conveyance roller 22R of the conveyance mechanism 22, and is sent out to the anvil roller 25a.

On the other hand, the stretchable continuous sheet 8a is sent to the anvil roller 25a from the Z-direction upper side of the low stretchable continuous sheet 9a by the pair of nip rolls 21R and 21R. And it conveys along the outer peripheral surface of the anvil roller 25a in the state piled up in the thickness direction (Z direction) with the low extensibility continuous sheet 9a sent out from the conveyance mechanism 22. FIG. In FIG. 8, on the outer peripheral surface of the anvil roller 25a, the stretchable continuous sheet 8a sent from the transport mechanism 21 and the low-extension continuous sheet 9a sent from the transport mechanism 22 are substantially 90% relative to the outer peripheral surface. It is wound at a predetermined winding angle such as ° or more. The stretchable continuous sheet 8a is superimposed on the surface opposite to the printing surface of the low stretchable continuous sheet 9a, and ultrasonic vibration energy is input when passing through the position of the horn 25h. 9a are joined together. Note that the stretch magnification of the stretchable continuous sheet 8a is set based on the speed difference between the circumferential speed V25a of the anvil roller 25a and the circumferential speed V21R of the nip roll 21R, as in the above-described embodiment.

8 differs from the case of FIG. 4 in the arrangement of the stretchable continuous sheet 8a and the low stretchable continuous sheet 9a with respect to the anvil roller 25a and the horn 25h in the joint 20 of the modified example of the production line LM shown in FIG. Specifically, in FIG. 4 described in the above-described embodiment, the stretchable continuous sheet 8a is disposed so as to face the anvil roller 25a of the joint portion 20, and low stretch so as to face the vibration surface of the horn 25h. Continuous sheet 9a was disposed. On the other hand, in FIG. 8 of the modified example, the low stretchable continuous sheet 9a is disposed so as to face the anvil roller 25a of the joint portion 20, and the stretchable continuous sheet 8a is disposed so as to face the vibration surface of the horn 25h. ing. And in a modification, it becomes the arrangement | positioning in which the printing surface of the image printed on the low extensibility continuous sheet 9a opposes the outer peripheral surface of the anvil roller 25a.

That is, in the production line LM of the modified example, when ultrasonic welding is performed by the joint portion 20, the image printed on the low-extension continuous sheet 9a and the vibration surface of the horn 25h are not in contact with each other. As described above, when performing ultrasonic welding, the ultrasonic vibration energy is applied to the sheet member brought into contact with the vibration surface of the horn 25h, thereby joining the sheet member by heating and melting. At this time, if an image is formed on the surface of the horn 25h that comes into contact with the vibration surface, the ink component forming the image adheres to the vibration surface of the horn 25h, thereby forming a weld portion having sufficient strength. You may not be able to do it. Further, when ink adheres to the horn 25h, the number of maintenances of the horn 25h increases, and when the horn 25h and the sheet member come into contact in the subsequent welding process, the ink attached to the horn is reversed. There is a possibility that the problem of moving to the member side and soiling the surface of the sheet member occurs. On the other hand, according to the configuration of this modification, the stretchable continuous sheet 8a on which no image is printed contacts the vibration surface of the horn 25h, and the low stretchable continuous sheet 9a on which the image is printed. Is arranged on the anvil roller 25a side. Therefore, the above-described problems hardly occur, and it is possible to increase the welding strength at the joint portion between the stretchable sheet 8 and the low stretchable sheet 9.

=== Other Embodiments ===
As mentioned above, although embodiment of this invention was described, said embodiment is for making an understanding of this invention easy, and is not for limiting and interpreting this invention. Further, the present invention can be changed or improved without departing from the gist thereof, and needless to say, the present invention includes equivalents thereof. For example, the following modifications are possible.

In the above-described embodiment, the joining unit 20 is provided on the downstream side in the transport direction of the printing unit 10, and the stretchable continuous sheet on the downstream side of the low stretchable continuous sheet 9 a on which the image is printed on the upstream side in the transport direction. Although the configuration is such that 8 a is bonded, another component may be provided between the printing unit 10 and the bonding unit 20. For example, the drying unit 50 may be provided between the printing unit 10 and the joining unit 20 in the production line LM. FIG. 9 is a diagram illustrating a case where the drying unit 50 is provided in the production line LM. The drying unit 50, for example, blows air on the printing surface (the surface on which the image is formed) of the low-extension continuous sheet 9a to be conveyed on the downstream side in the conveyance direction of the printing unit 10 or the ambient ambient temperature. Or the like, the drying of the ink droplets landed on the low-extension continuous sheet 9a is promoted. By providing the drying unit 50 to facilitate drying of the printing surface, it is possible to quickly fix the image formed on the surface of the low-extension continuous sheet 9a and to make the low-extension continuous sheet 9a easy to handle. . For example, by quickly drying the printing surface, it becomes difficult for the ink to move to other elements, so that a conveyance roller (CV) is brought into contact with the printing surface, or other processing is performed on the printing surface. It becomes possible.

In the above-described embodiment, the printing device 15 provided in the printing unit 10 is a so-called line printer type ink jet printer that ejects ink from a head whose position is fixed with respect to a transported print medium. The aspect of the printing apparatus is not limited to this. For example, it may be a printer of a type in which a head unit that ejects ink is mounted on a carriage and ink is ejected while the head unit moves relative to the print medium by moving the carriage. Other types of printers may also be used.

In the above-described embodiment, as shown in FIG. 4, the joining of the stretchable continuous sheet 8 a and the low stretchable continuous sheet 9 a made at the joint portion 20 is performed by the ultrasonic welding device 25, but this Not exclusively. For example, instead of the ultrasonic welding device 25, a heat seal processing device or a crimping device may be used. Note that the configuration of the heat seal processing apparatus and the configuration of the crimping processing apparatus are similar to each other. That is, the difference in configuration between the two is mainly in the presence or absence of heating of the roll, both devices have a pair of upper and lower rolls that are driven to rotate around the rotation axis along the CD direction, Each of these rolls is configured to rotate at a peripheral speed value equal to the peripheral speed value V25a of the anvil roller 25a in the case of the ultrasonic welding device 25 described above. According to such a configuration, the roll gap between the rolls is overlapped with the stretchable continuous sheet 8a stretched to the standard stretched state and the low stretchable continuous sheet 9a stretched. The two

sheets

8a and 9a are clamped by these rolls during the passage, whereby the two

sheets

8a and 9a are welded or pressed together and fixed together. By the way, in the case of adopting the pressure bonding method, before the pressure bonding, hot melt bonding with a predetermined application pattern to at least one of the stretchable continuous sheet 8a and the low stretchable continuous sheet 9a. An adhesive such as an agent may be applied.

In the above-described embodiment, the stretchable continuous sheet 8a is fixed to the low-extension continuous sheet 9a in the joint portion 20, but another sheet may be added or fixed as a single sheet or a plurality of sheets. . In addition, as a sheet | seat fixed additionally, an elastic sheet may be sufficient and a low extensible sheet | seat may be sufficient. Moreover, the form of the sheet may be a nonwoven fabric, a woven fabric, or a film.

1 disposable diapers (absorbent articles, diapers),
3 Absorbent body, 3e end,
3c absorbent core,
4 Top sheet,
5 Leak-proof sheet,
7 exterior sheet,
7f ventral side, 7c crotch, 7b dorsal side, 7eW end,
7a Continuous sheet of exterior sheet (exterior sheet, base sheet),
8 Inner layer sheet (elastic sheet),
8a Continuous sheet of stretchable sheet (stretchable continuous sheet),
9 Outer layer sheet (low stretch sheet),
9a Continuous sheet of low stretch sheet (low stretch continuous sheet),
10 Printing department,
11 transport mechanism, 11R transport roller,
15 printing device,
151 head unit,
151K black head unit, 151K1 ~ 151K4 head,
151C Cyan head unit, 151C1 ~ 151C4 head,
151M magenta head unit, 151M1-151M4 head,
151Y yellow head unit, 151Y1 ~ 151Y4 head,
152 ink tank, 153 controller,
20 joints,
21 Conveying mechanism of the stretchable

continuous sheet

8a, 21R nip roll,
22 Conveying mechanism of low-extension

continuous sheet

9a, 22R conveying roller,
25 ultrasonic welding equipment, 25h horn, 25a anvil roller,
50 drying section,
HB waist opening, HL leg opening,
CV transport mechanism, CVR reversing roller,
j junction, jL vertically long strip, jW lateral strip, jC joint,
LM production line,
Nz nozzle

Claims

A composite sheet manufacturing method for manufacturing a composite sheet having an elastic sheet according to an absorbent article and a low extensibility sheet having lower extensibility than the elastic sheet,
Conveying the low extensible sheet along a conveying path;
Discharging ink droplets toward the low stretch sheet transported along the transport path and printing an image on the surface of the low stretch sheet at a predetermined position of the transport path;
Joining the stretchable sheet to the low stretchable sheet at a position downstream of the predetermined position in the transport path in the transport direction while transporting the stretchable sheet in an extended state;
The composite sheet manufacturing method characterized by having.
The composite sheet manufacturing method according to claim 1,
In the low-extensible sheet, the stretchable sheet is bonded to a surface opposite to the surface on which the image is printed.
A composite sheet manufacturing method according to claim 1 or 2,
Joining the low stretch sheet and the stretch sheet,
Using a horn portion having a vibration surface that vibrates ultrasonically, and a rotatable roller portion having an outer peripheral surface that receives vibration of the vibration surface,
The composite sheet manufacturing is performed by applying ultrasonic vibration from the horn unit to the low-extensible sheet and the stretchable sheet that are superposed on each other on the outer peripheral surface of the roller unit. Method.
It is a composite sheet manufacturing method of Claim 3, Comprising:
The stretchable sheet is stretched to a predetermined stretch magnification based on the difference between the peripheral speed when the roller portion rotates and the peripheral speed when the nip roll that transports the stretchable sheet rotates. A method for producing a composite sheet, wherein the composite sheet is conveyed.
A composite sheet manufacturing method according to claim 3 or 4,
When the low stretch sheet and the stretch sheet are joined,
The method for producing a composite sheet, wherein the low extensible sheet is disposed on the roller portion side, and the stretchable sheet is disposed on the horn portion side.
A composite sheet manufacturing method according to any one of claims 1 to 5,
The stretchable sheet has a structure having a plurality of fibers entangled with each other so as to have a density and a plurality of voids formed between the fibers.
A composite sheet manufacturing method according to any one of claims 1 to 6,
Between the printing being performed and the joining being performed,
A method for producing a composite sheet, comprising drying an image printed on the low-extension sheet.
A composite sheet manufacturing apparatus that manufactures a composite sheet having an elastic sheet according to an absorbent article, and a low extensibility sheet having lower extensibility than the elastic sheet,
A transport unit that transports the low-extensible sheet along a transport path;
A printing unit that ejects ink droplets toward the low-extensible sheet conveyed along the conveyance path and prints an image on the surface of the low-extensible sheet at a predetermined position in the conveyance path;
A joint that joins the stretchable sheet to the low stretchable sheet at a position downstream of the predetermined position in the transport path while transporting the stretchable sheet in a stretched state,
A composite sheet manufacturing apparatus comprising: