JP5866485B1 - Composite sheet manufacturing method and composite sheet manufacturing apparatus - Google Patents

Abstract

In the composite sheet manufacturing method which manufactures the composite sheet (7A) which has the elastic sheet (8A) which concerns on an absorbent article, and the low extensibility sheet (9A) whose extensibility is lower than the said elastic sheet (8A). A printing step (10) for printing an image (G) on a surface of the low-extension sheet (9A) by discharging droplets of aqueous ink toward the low-extension sheet (9A); A contact step (20) in which heated air is brought into contact with the low stretch sheet (9A) on which the image (G) is printed, and the low stretch sheet (9A) after the contact step (20). Bonding step (50) for bonding the stretchable sheet (8A) in an expanded state.

Description

  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, in order to improve the design on the appearance or make it easy to distinguish the front and back of the diaper at a glance, a pattern or a letter is attached to the outer member 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

Inkjet printing is known as a method for printing an image with good image quality on a diaper. In inkjet printing, an ink droplet is ejected from a printing device and landed on a base sheet (for example, a nonwoven fabric) that forms a diaper, whereby an image is printed on a landing portion of the ink droplet.
When performing ink jet printing in a diaper production line that continuously produces diapers, it is necessary to quickly dry the ink so that the ink that has landed on the base sheet does not adhere to the equipment or equipment that constitutes the diaper production line. is there. Therefore, in order to efficiently manufacture a diaper (base sheet), a process such as drying the ink by blowing heated air onto the base sheet on the production line may be performed. However, when the base sheet is a composite sheet member having stretchability, an elastomer or the like that exhibits stretchability is stretched by blowing heated air on the composite sheet member, and the stretchability of the base sheet is lost. There is a risk that.

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

The main invention for achieving the above object is:
A composite sheet manufacturing method for manufacturing a composite sheet having a stretchable sheet made of a nonwoven fabric according to an absorbent article and a low stretchable sheet made of a nonwoven fabric that is less stretchable than the stretchable sheet,
A printing step of ejecting water-based ink droplets toward the low extensible sheet to print an image on the surface of the low extensible sheet;
A contact step of bringing heated air into contact with the low-extension sheet on which the image is printed;
After the contacting step, a joining step of joining the stretchable sheet in an elongated state to the low stretchable sheet;
Have
After the said joining process, it is a composite sheet manufacturing method characterized by not having the process of heating the said low extensible sheet | seat and the said elastic sheet .
Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

  ADVANTAGE OF THE INVENTION According to this invention, the sheet | seat member which has the elasticity which the favorable image was printed can be manufactured efficiently.

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. 2 is a side view illustrating a configuration of a printing unit 10. FIG. 2 is an explanatory diagram of a head unit 12 of a printing unit 10. FIG. It is explanatory drawing of the image G before and behind contraction. FIG. 3 is an explanatory diagram of a configuration of a linear conveyance type drying apparatus 21. It is sectional drawing of the blower outlet 213. FIG. 3 is a configuration diagram of a drum-type drying device 25. FIG. FIG. 11A is an explanatory diagram of a cross-sectional structure of the outer peripheral surface of the first drum 252A. FIG. 11B is an explanatory diagram of the metal plate 271. FIG. 11C is an explanatory diagram of the mesh member 272. 3 is a side view illustrating a configuration of an inspection unit 40. FIG. It is process explanatory drawing after the production | generation of the exterior continuous sheet 7A until completion of the diaper 1. FIG.

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 comprising: an elastic sheet according to an absorbent article; and a low extensibility sheet having a lower extensibility than the elastic sheet, the aqueous sheet toward the low extensibility sheet A printing step of ejecting ink droplets to print an image on the surface of the low extensible sheet; a contacting step of bringing heated air into contact with the low extensible sheet on which the image is printed; and the contact And a joining step of joining the stretchable sheet in the stretched state to the low stretchable sheet after the step.

  According to such a composite sheet manufacturing method, an image is printed on a low-extension sheet, and the printing surface is dried with heated air, and then bonded to the stretchable sheet, whereby the ink is firmly fixed on the low-extension sheet. And good images can be formed. In addition, since the stretchable sheet is not heated in the drying step, the composite sheet after being joined to the low stretchable sheet can exhibit stretchability. Therefore, it is possible to efficiently manufacture a stretchable sheet member on which a good image is printed.

  In this composite sheet manufacturing method, it is preferable that in the contacting step, the heated air flows through the low-extensible sheet in the thickness direction.

  According to such a composite sheet manufacturing method, the heated air easily comes into contact with the internal fibers by flowing so that the heated air passes through the gaps between the fibers of the low-extension sheet. Thereby, the ink which penetrate | infiltrated the inside of a low extensible sheet | seat can be dried efficiently.

  In this composite sheet manufacturing method, it is preferable that the heated air flows from the surface on which the image is printed toward the other surface in the thickness direction of the low-extension sheet. .

  According to such a composite sheet manufacturing method, the closer to the printing surface on which an image is printed, the larger the amount of ink adhering to the fiber, so that heated air flows from the printing surface side to the opposite surface side of the low stretch sheet. As a result, the ink that has penetrated into the interior of the low-extension sheet can be more easily dried.

  In this composite sheet manufacturing method, in the contacting step, the sheet is conveyed and formed on the outer peripheral surface by rotating the drum while holding the low-extensible sheet on the outer peripheral surface of the drum. It is desirable to pass the heated air through the vent hole.

  According to such a composite sheet manufacturing method, the heated air can be passed in the thickness direction of the low stretch sheet while the low stretch sheet is conveyed while being held on the outer peripheral surface of the drum. Accordingly, the low-extension continuous sheet 9A is less likely to bend when passing the drying air, and the drying of the ink can be promoted without causing a shift during conveyance.

  In such a composite sheet manufacturing method, it is desirable to include a cooling step for cooling the low-extension sheet between the contact step and the joining step.

  According to such a composite sheet manufacturing method, it is possible to firmly fix the ink inside the low-extension sheet by cooling the dried ink by contact with the heating gas. In addition, by cooling the low stretch sheet before joining to the stretch sheet and preventing heat from being transmitted to the elastomer of the stretch sheet, it is possible to prevent the stretchability of the composite sheet from being impaired. .

  In such a composite sheet manufacturing method, it is preferable that an inspection step of inspecting an image quality of an image printed on the low-extensible sheet is provided between the contact step and the joining step.

  According to such a composite sheet manufacturing method, it is easy to accurately determine the image quality of a printed image by inspecting the image after drying the ink. In addition, if an inspection process is provided on the production line of the low-extensible sheet, it is possible to reduce the burden of inspection and the inspection time, and to respond quickly when a problem occurs.

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

  According to such a composite sheet manufacturing method, when the sheet members are bonded to each other, bonding failure due to ink can be suppressed by bonding on the surface opposite to the printing surface of the image, and the bonding strength of the composite sheet member is increased. Can keep.

  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 a roller part, and by applying 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 that the low extensible sheet is disposed on the roller portion side and the stretchable sheet is disposed on the horn portion side.

  According to such a composite sheet manufacturing method, since the horn part (ultrasonic horn) does not touch the printing surface of the low-extensible sheet, it is possible to suppress the occurrence of ink contamination or poor welding. Moreover, even if the printing surface side of the low-extension sheet contacts the outer peripheral surface of the roller portion (anvil roller), the ink is dried and fixed to the sheet member by a drying process (contact process) or a cooling process after printing. Therefore, contamination or the like due to ink hardly occurs even in the roller portion.

  In this composite sheet manufacturing method, it is desirable that the surface of the low-extension sheet on which the image is printed is disposed on the outermost surface of the absorbent article.

  According to such a composite sheet manufacturing method, since an image is formed on the outermost surface of the absorbent article (diaper), the image is easily visible. Further, in the image, since the ink is firmly fixed on the sheet member and the printing surface has good friction resistance, the image quality is hardly deteriorated even when formed on the outermost surface of the absorbent article.

  In this composite sheet manufacturing method, it is desirable that the joining step does not include a step of heating the low-extension sheet and the stretchable sheet.

  According to such a composite sheet manufacturing method, excessive heat is not applied to the stretchable sheet throughout the manufacturing process of the composite sheet, so that the stretchability of the thermoplastic elastomer constituting the stretchable sheet is lost. It is suppressed. Thereby, a composite sheet (diaper) can maintain favorable elasticity.

  In this composite sheet manufacturing method, the low-extensible sheet is transported after the contacting step until it is joined to the stretchable sheet, rather than the distance transported while the stretchable sheet is stretched. It is desirable that the distance is longer.

  According to such a composite sheet manufacturing method, before joining to the stretchable sheet, by transporting the low stretchable sheet that is in contact with the heated gas and having a high temperature through a sufficiently long transport path, The temperature of the low-extensible sheet can be easily lowered. Thereby, it becomes easier to suppress the loss of stretchability of the stretchable sheet.

  Further, a composite sheet manufacturing apparatus that manufactures a composite sheet having an elastic sheet according to an absorbent article and a low-extensible sheet that is less extensible than the elastic sheet, A printing unit that discharges water-based ink droplets to print an image on the surface of the low-extension sheet; and a contact unit that contacts heated air to the low-extension sheet on which the image is printed; A composite sheet manufacturing apparatus comprising: a sheet member joining portion that joins the stretchable sheet in a stretched state to the low stretchable sheet after contacting heated air.

  According to such a composite sheet manufacturing apparatus, an image is printed on a low-extension sheet, and the printed surface is dried by heated air and then joined to the stretchable sheet. The sheet member on which the image is printed can be efficiently manufactured.

=== Embodiment ===
First, a basic structure of a pants-type diaper 1 (hereinafter also simply referred to as “diaper 1”) as an example of an absorbent article formed by the sheet member according to the present embodiment will be described, and then a sheet member production line LM Will be described.

<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, the side that is located on the non-skin side of the wearer. The power side is simply called the “non-skin side”.

  The diaper 1 is a so-called two-piece type diaper. That is, the diaper 1 has an absorbent main body 3 that absorbs excreted fluid such as urine as a first component. And the non-skin side surface of the absorptive main body 3 is provided, and it has the planar view substantially hourglass-shaped exterior sheet 7 which makes the exterior of the diaper 1 as a 2nd component.

  The absorptive main body 3 has an absorptive core 3c that absorbs excretory fluid. The absorptive core 3c is formed by molding liquid absorptive fibers such as pulp fibers and liquid absorptive granular materials such as superabsorbent polymers into a predetermined shape (for example, a rectangular shape). 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 is provided with the surface. A liquid-impermeable leak-proof sheet 5 such as a film is provided so as to cover the entire surface.

  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.

  As shown in FIG. 3, a so-called laminate sheet 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 joining portion between the inner layer sheet 8 and the outer layer sheet 9 is welded with a predetermined joining pattern (not shown) formed by discontinuous dispersion.

  As the material for 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, as the material for the outer layer sheet 9, low stretchability is low in the width direction of the diaper 1. An extensible sheet 9 is used. And in the state where the stretchable inner layer sheet 8 is stretched in the width direction to a predetermined stretch ratio such as 2.5 times the natural length (hereinafter also referred to as the stretched state), the stretch is also low stretch in the state stretched in the width direction. The sheet 8 and 9 are superposed on the outer layer sheet 9 and fixed integrally with the above-mentioned bonding 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 is bent in the width direction, whereby the outer layer sheet 9 quickly follows the contraction of the inner layer sheet 8 to shorten 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 bending of the outer layer sheet 9. It is in a state where there are multiple wings. 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.

  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 good that it is an arbitrary value in the range of 0% to 40%. More desirably, the elongation percentage 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 the value 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 extensible sheet 9” is an extensible sheet lower than the stretchable 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 this embodiment, the elastic sheet 8 and the low extensibility sheet 9 are demonstrated as what is comprised with the nonwoven fabric. However, the stretchable sheet 8 and the low stretchable sheet 9 may be composed of other sheets such as woven fabric.

  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 properties of the thermoplastic elastomer fibers can be reduced. The non-woven fabric can be changed to a structure that hardly inhibits general stretch deformation, whereby the stretchability of the non-woven fabric is expressed and the stretchable sheet 8 can be used.

  Since such a stretchable sheet 8 is configured in a state where a plurality of fibers are randomly entangled, when viewed microscopically, the stretchable sheet 8 has a structure having a plurality of voids between the fibers. . 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. The low-extension sheet 9 also has a structure having a plurality of voids between entangled fibers.

  As shown in FIG. 3, the absorbent main body 3 is joined at the joint J on the skin side of the exterior sheet 7. And the exterior sheet | seat 7 to which the absorptive main body 3 was attached is folded in half by the crotch part 7c, and the abdominal side part 7f and the back side part 7b are overlapped. 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 addition, in the underpants type diaper 1 of this embodiment, the image G which consists of a predetermined character, a pattern, a character, etc. is printed on the exterior sheet 7 (refer 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). .

<Method for manufacturing exterior sheet 7>
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 as a material a continuous sheet 8A of the stretchable sheet 8 (hereinafter also referred to as a stretchable continuous sheet 8A) and a continuous sheet 9A of a low stretchable sheet 9 (hereinafter also referred to as a low stretchable continuous sheet 9A). Thus, a continuous sheet 7A in which the exterior sheet 7 is continuous in the width direction (hereinafter also referred to as an exterior continuous sheet 7A) is generated. The production line LM includes a transport mechanism CV, a printing unit 10, a drying unit 20, a cooling unit 30, an inspection unit 40, and a sheet member joining unit 50.

  The conveyance mechanism CV is a conveyance unit that continuously conveys the stretchable continuous sheet 8A (interior sheet 8), the low-extension continuous sheet 9A (exterior sheet 9), or both along a predetermined conveyance 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-extension continuous sheet 9A is transported in a line in the transport direction while aligning the direction corresponding to the width direction of the diaper 1 with the transport direction. Similarly, the stretchable continuous sheet 8A is also transported in a line in the transport direction while aligning the direction corresponding to the width direction of the diaper 1 with the transport direction.

  Further, in the following description, the above-described transport direction set on the production line LM may be referred to as “MD direction”. The MD direction can be different depending on the type of the sheet, and even the same sheet can be different depending on the conveyance place. One of the two directions orthogonal to the MD direction may be referred to as a “CD direction”, and the other may be referred to as a “Z direction”. The CD direction is a direction parallel to the width direction of each sheet, and is a direction perpendicular to the paper surface of FIG. The Z direction is a direction parallel to the thickness direction of each sheet.

(Printer 10)
The low-extension continuous sheet 9A conveyed by the conveyance mechanism CV is printed in the process of being conveyed downstream in the MD direction by the printing unit 10 (printing process). The printing unit 10 of the present embodiment is an inkjet printing apparatus that forms an image G by ejecting ink droplets from a large number of nozzles Nz and landing on the low-extension continuous sheet 9A.

  FIG. 5 is a side view illustrating the configuration of the printing unit 10. FIG. 6 is an explanatory diagram of the head unit 12 of the printing unit 10. The printing unit 10 includes a head unit 12, a transport roller 13, and a printing control unit 14. In the following description, the surface of the low-extension continuous sheet 9A that faces the head unit 12, that is, the surface on which the image is formed on the low-extension continuous sheet 9A is referred to as a “printing surface”. There is.

  The head unit 12 is an ink ejection unit that has a plurality of nozzles Nz arranged in the CD direction and ejects ink droplets from each nozzle Nz. The head unit 12 is provided for each color of ink (cyan ink, magenta ink, yellow ink, black ink). A plurality (four in this case) of head units 12 are arranged along the MD direction. Each head unit 12 has a plurality (four in this case) of heads 121 arranged in a staggered pattern along the CD direction, and each head 121 has a plurality of nozzles Nz arranged in the CD direction. . Thereby, each head unit 12 can discharge ink to the whole area | region of the width direction of the low extensibility continuous sheet 9A which is a to-be-printed medium. The head unit 12 may be capable of ejecting a plurality of colors of ink. Moreover, the head 121 of the head unit 12 may be one, and may be three or more. Further, the ink droplet ejection method by the head 121 may be a piezoelectric method using a piezoelectric element, a thermal method using a heater, or another method.

  The conveyance roller 13 is a rotation roller that conveys the low-extension continuous sheet 9A. The conveyance roller 13 supports the low extensibility continuous sheet 9 </ b> A in the thickness direction, so that the interval between the nozzle Nz of the head unit 12 and the low extensibility continuous sheet 9 </ b> A is maintained. The transport roller 13 is disposed at a position not facing the nozzle Nz of the head unit 12. This is because the low-extension continuous sheet 9A, which is a printing medium, is a nonwoven fabric, and ink droplets may pass between the fibers of the nonwoven fabric. Further, as shown in FIG. 5, the transport roller 13 may be disposed at a position between the head units 12 and 12 in the MD direction, and thus the interval between the transport rollers 13 arranged adjacent to each other in the MD direction. By shortening, it becomes easy to suppress the low extensibility continuous sheet 9A from being bent during conveyance.

  The print control unit 14 is a control unit that controls the operation of the printing unit 10. For example, the print control unit 14 controls the ejection timing and ejection amount of ink droplets ejected from the nozzles Nz of the head unit 12 by controlling the head unit 12.

  By the way, in the sheet member joint portion 50 described later (see FIG. 4), after the stretchable continuous sheet 8A and the low stretchable continuous sheet 9A are stretched in the MD direction, the stretchable state is released when the stretched state is released. As the continuous continuous sheet 8A contracts in the MD direction (width direction of the diaper 1; see FIG. 3), the low stretchable continuous sheet 9A contracts in the MD direction while forming a plurality of wrinkles. In consideration of the shrinkage, the printing unit 10 prints the image G on the low-extension continuous sheet 9A. FIG. 7 is an explanatory diagram of the image G before and after contraction. The upper diagram of FIG. 7 is an explanatory diagram of the final image G after contraction. The lower diagram of FIG. 7 is an image G printed on the low-extension continuous sheet 9A, and is an explanatory diagram of the image G before contraction. For example, when the expansion ratio of the stretchable continuous sheet 8A is 1.5 times, an image G (see the lower diagram) is generated by expanding the image G to be printed (see the upper diagram) by 1.5 times in the MD direction. At the same time, the image G stretched in the MD direction is inkjet printed on the low-stretch continuous sheet 9A. The image G expanded in the MD direction (see the figure below) may be generated by the print control unit 14, or may be generated by an external image processing device and transmitted to the print control unit 14.

  Since the printing unit 10 performs printing using the low-stretch continuous sheet 9A having a small elongation rate as a printing medium, it is easy to form a good image G. Assuming that inkjet printing is performed using the stretchable continuous sheet 8A as a printing medium, the stretchable continuous sheet 8A is stretched during transport, so that a gap (gap) between the fibers on the surface is likely to widen. As a result, it may be difficult to print an image G with good image quality because the deviation of the landing positions of the ink droplets increases or the ink droplets pass through the back side of the stretchable continuous sheet 8A. On the other hand, the low-stretch continuous sheet 9A has a smaller gap between the fibers than the stretchable continuous sheet 8A, and the surface is easily maintained in a uniform state. The image quality of the image G can be made favorable.

  Since there is a gap (gap) between fibers on the surface of the low-stretch continuous sheet 9A that is a nonwoven fabric, the ink that has landed from the printing surface side passes through the gap between the fibers on the surface and passes through the gap between the fibers on the surface. Penetrates inside. That is, the ink adheres not only to the fibers on the surface of the low-extension continuous sheet 9A but also to the fibers inside the low-extension continuous sheet 9A. Further, since the ink is applied from the printing surface side, the closer to the printing surface, the more ink is attached to the fibers.

(Drying part 20)
When ink-jet printing is performed on the low-stretch continuous sheet 9A that is a non-woven fabric, if the ink droplets are small, the ink droplets pass through the voids between the fibers of the low-stretch continuous sheet 9A, resulting in insufficient print density. May end up. For this reason, the printing unit 10 ejects relatively large ink droplets onto the low-extension continuous sheet 9A. However, when ink jet printing is performed with large ink droplets, the amount of ink adhering to the low extensibility continuous sheet 9A increases, and thus drying tends to be insufficient. In addition, when an inkjet printing process is incorporated in the production line LM of the diaper 1, if the drying after inkjet printing is insufficient, each device (for example, sheet member bonding) disposed on the downstream side in the MD direction of the printing unit 10 Part 50), the transport roller of the transport mechanism CV, and the like may be stained with ink. Therefore, the production line LM of the present embodiment includes a step (contact step) of drying the ink by causing the drying unit 20 to contact the heated air with the low-extension continuous sheet 9A. That is, the drying part 20 is a contact part which makes heating air contact the low-extension continuous sheet 9A. The heated air is a gas for drying the ink forming the image G. For example, the heated air is dehumidified and heated to about 80 °. The drying unit 20 (contact unit) of the present embodiment includes a linear conveyance type drying device 21 and a drum type drying device 25.

・ Linear conveying type dryer 21
FIG. 8 is an explanatory diagram of the configuration of the linear conveyance type drying apparatus 21. The linear conveyance type drying apparatus 21 is an apparatus that is disposed on the downstream side in the MD direction of the printing unit 10 and dries the low-extension continuous sheet 9A subjected to inkjet printing in a linear conveyance path. The linear conveyance type drying apparatus 21 includes a drying chamber 211, a conveyance support roller 212, a plurality of air outlets 213, and a pressure chamber 214.

  The drying chamber 211 is a member that partitions a drying region around the conveyance path of the low-extension continuous sheet 9A. The inside of the drying chamber 211 is kept at a high temperature, and the low-extension continuous sheet 9A is heated in the drying chamber 211. The conveyance support roller 212 is a rotation roller that conveys the low-extensible continuous sheet 9A while supporting it. The conveyance support roller 212 may be rotated by a driving force of a motor, or may be rotated passively by contacting the low-extension continuous sheet 9A.

  The blower outlet 213 is a part which blows out heated air. In the linear conveyance type drying apparatus 21 of FIG. 8, a plurality of air outlets 213 are provided for the pressurizing chamber 214 for supplying heated air, and uniform from each of the air outlets 213 toward the low-extension continuous sheet 9A. Hot air can be blown out. FIG. 9 is a cross-sectional view of the air outlet 213. The blower outlet 213 has a slit-shaped opening 231 in which an opening having a width W in the MD direction extends in the CD direction. In addition, a constriction portion 232 and a rectification portion 233 that serve as a flow path for heated air are formed inside the air outlet 213. The heated air supplied from the pressurizing chamber 214 flows from the heated air supply hole 23h into the throttle unit 232, moves to the rectifying unit 233 side while narrowing the flow path, is rectified, and is then ejected from the opening 231. The Thereby, the blower outlet 213 can spray heating air to the whole area | region of the width direction (CD direction) of the low extensibility continuous sheet 9A.

  In the drying unit 20 of the present embodiment, heated air is sprayed from the lower side to the upper side in the thickness direction on the low-extension continuous sheet 9A. That is, heated air is blown to the surface (printing surface) side on which the image G is printed by the low-extension continuous sheet 9A (see FIGS. 4 and 8). The sprayed heated air flows so as to penetrate the low-extension continuous sheet 9A in the thickness direction using the gap between the fibers as a flow path, and heats the inside of the low-extension continuous sheet 9A. In this embodiment, when ink jet printing is performed on the low-stretch continuous sheet 9A, which is a nonwoven fabric, the ink penetrates through the voids on the surface of the nonwoven fabric, so the low-stretch continuous sheet 9A is heated to a high temperature. It is difficult to sufficiently dry the ink adhering to the fibers inside the sheet member only by placing it in the atmosphere (drying chamber 211). However, since the heated air is easily brought into contact with the internal fibers by spraying the heated air and passing through the gaps between the fibers of the low-extensible continuous sheet 9A, the ink penetrated into the low-extensible continuous sheet 9A. Can be efficiently dried. Moreover, since the amount of ink adhering to the fiber increases as it is closer to the printing surface, the ink can be more easily dried by disposing the air outlet 213 on the printing surface side of the low-extension continuous sheet 9A. However, it is possible to dry the ink even if the drying unit 20 is arranged so that the heated air is ejected from the upper side to the lower side in the thickness direction of the low-extension continuous sheet 9A in FIG.

  In the printing process of the present embodiment, when the low-extension continuous sheet 9A is conveyed in the drying chamber 211, a predetermined tension that does not cause plastic deformation is applied to the low-extension continuous sheet 9A, and the tension is applied. The drying air is allowed to pass in the thickness direction of the low-extension continuous sheet 9A. Thereby, since the space | gap between fibers spreads, the air for drying can be passed in the state which reduced the pressure loss. In addition, this can increase the flow rate of the drying air that passes through the low-extension continuous sheet 9A, and can promote the drying of the ink. Note that it is permissible to apply tension to the low-extension continuous sheet 9A so as not to be plastically deformed (to the extent that the low-extension sheet is not damaged). Even when the tension is applied to such an extent that the plastic deformation does not occur, the gap between the fibers becomes wider than when no tension is applied, and the pressure loss can be reduced.

  The drying chamber 211 of the drying unit 20 may be provided with a suction port (not shown) that sucks heated air that has penetrated the low-extension continuous sheet 9A. By sucking the heated air that has passed through the low extensibility continuous sheet 9A from the suction port, the heated air easily passes through the low extensibility continuous sheet 9A.

・ Drum-type drying device 25
FIG. 10 is a configuration diagram of the drum-type drying device 25. The drum-type drying device 25 includes a first drum drying device 25A and a second drum drying device 25B. The first drum drying device 25A includes a first drum drying chamber 251A, a first drum 252A, a plurality of air outlets 253, a pressure chamber 254, and a suction port 256. Similarly, the second drum drying device 25B includes a second drum drying chamber 251B, a second drum 252B, a plurality of outlets 253, a pressurizing chamber 254, and a suction port 256. The first drum drying device 25A is arranged on the upstream side in the MD direction with respect to the second drum drying device 25B. Since the configurations of the first drum drying device 25A and the second drum drying device 25B are substantially the same, the first drum drying device 25A will be described here, and the description of the second drum drying device 25B will be omitted.

  The first drum drying chamber 251A is a member that divides a drying region around the first drum 252A serving as a conveyance path for the low-extension continuous sheet 9A. Note that the first drum drying chamber 251A and the second drum drying chamber 251B may be shared without being divided. The first drum 252A is a rotating drum that conveys the low extensibility continuous sheet 9A by rotating while holding the low extensibility continuous sheet 9A on the outer peripheral surface. Since the low extensibility continuous sheet 9A is held on the outer peripheral surface of the first drum 252A, the thickness is smaller than the case where the low extensibility continuous sheet 9A is supported by the conveyance roller as in the linear conveyance type drying device 21 described above. The low extensibility continuous sheet 9A is difficult to bend when the drying air is passed in the direction. The first drum 252A is rotated by a drive motor (not shown), whereby the low-extension continuous sheet 9A is conveyed.

  FIG. 11A is an explanatory diagram of a cross-sectional structure of the outer peripheral surface of the first drum 252A. FIG. 11B is an explanatory diagram of the metal plate 271. FIG. 11C is an explanatory diagram of the mesh member 272. As shown in FIG. 11A, the outer peripheral surface of the first drum 252A is configured by overlapping a metal plate 271 and a mesh member 272. The metal plate 271 is a so-called punching metal in which a number of punched holes to be vent holes are formed (see FIG. 11B). On the metal plate 271, for example, round punched holes having a diameter D of 5 mm are arranged in a staggered pattern of 60 degrees with a pitch P of 8 mm. The mesh member 272 is a mesh member formed by weaving a wire material into a mesh, and the mesh becomes a vent (see FIG. 11C). The net-like member 272 may be, for example, a metal net plain-woven with a metal wire, or a plastic net plain-woven with a plastic wire. The mesh (interval between the wire rod) of the mesh member 272 is set smaller than the diameter of the punched hole of the metal plate 271. Since the mesh of the mesh member 272 is small, when the low-extension continuous sheet 9 </ b> A is held on the peripheral surface of the drum, the traces of the vent holes are not likely to remain, and the mesh member 272 is supported by the metal plate 271. Deformation can also be suppressed.

  The blower outlet 253 is a part which blows off the drying air (see FIG. 10). The air outlet 253 of the drum type drying device 25 has substantially the same shape as the air outlet 213 of the linear conveyance type drying device 21 (see FIG. 9), and air for drying is blown out from a slit-like opening elongated in the CD direction. . In the first drum drying device 25A of FIG. 10, a plurality of air outlets 253 are provided for the pressurizing chamber 254 for supplying heated air so that each air outlet 253 faces the outer peripheral surface of the first drum 252A. Is arranged. By supplying the low extensibility continuous sheet 9A so that the printing surface faces the outside with respect to the outer peripheral surface of the first drum 252A, the printing surface faces the air outlet 253, and the air outlet 253 is a low extensibility continuous sheet. Drying air is blown out toward the printing surface of 9A. Since the amount of ink adhering to the fiber is larger as it is closer to the printing surface, the low stretchable continuous sheet 9A is supplied to the first drum 252A so that the printing surface of the low stretchable continuous sheet 9A faces the outside. It becomes easy to dry.

  Further, when supplying the low-extension continuous sheet 9A to the first drum 252A, a predetermined tension that does not cause plastic deformation is applied to the low-extension continuous sheet 9A, and the first drum is in a state in which the tension is applied. The low extensibility continuous sheet 9A is held on the outer peripheral surface of 252A (or the second drum 252B). Thereby, since the space | gap between fibers spreads, the air for drying can be passed in the state which reduced the pressure loss. In addition, this can increase the flow rate of the drying air that passes through the low-extension continuous sheet 9A, and can promote the drying of the ink.

  The suction port 256 is a part that sucks the drying air that has passed through the low-extension continuous sheet 9A from the inside of the first drum 252A. When the suction port 256 sucks the drying air, the inside of the first drum 252A becomes a reduced pressure atmosphere. Thereby, since the low-extension continuous sheet 9A is adsorbed on the outer peripheral surface, the low-extension continuous sheet 9A held on the first drum 252A is less likely to be displaced during conveyance. Further, since the inside of the first drum 252A is in a reduced pressure atmosphere, a pressure difference can be formed on the front and back of the low-extension continuous sheet 9A, and drying air can be passed in the thickness direction of the low-extension continuous sheet 9A. it can. In particular, in the region facing the air outlet 253, the drying air can be easily passed in the thickness direction of the low-extension continuous sheet 9A.

(Cooling unit 30)
The low elongation continuous sheet 9A sprayed with heated air by the drying unit 20 is subsequently cooled by the cooling unit 30 (cooling step). The cooling unit 30 is a mechanism that cools the temperature of the low-extension continuous sheet 9A to around room temperature (for example, about 25 ° C.), and has a configuration equivalent to the linear conveyance type drying device 21 of the drying unit 20 (see FIG. 8). In other words, the cooling unit 30 includes a cooling chamber, a conveyance support roller, a plurality of air outlets, and a pressurizing chamber (all are not shown). Spray on. Since the configuration and functions of the cooling unit 30 are substantially the same as those of the linear conveyance type drying apparatus 21, a detailed description of the configuration of the cooling unit 30 is omitted here.

  In the cooling unit 30, cooling air is supplied from the pressurizing chamber, and the cooling air is sprayed from the plurality of outlets onto the printing surface side of the low-extension continuous sheet 9 </ b> A. The cooling air may be air whose temperature has been adjusted to be lower than room temperature, or indoor air may be used as it is. The blown cooling air flows so as to penetrate through the low-extension continuous sheet 9A in the thickness direction by passing through the gaps between the fibers of the nonwoven fabric in the same manner as described in the linear conveyance type drying device 21. The fibers and ink inside the stretchable continuous sheet 9A are cooled. Thereby, the ink can be firmly fixed inside the low-extension continuous sheet 9A.

  Note that the configuration of the cooling unit 30 is not limited to the above example, and other configurations may be used as long as the low-extension continuous sheet 9A can be cooled. For example, a configuration in which the low stretchable continuous sheet 9A only passes through the inside of the cooling chamber may be used, or a configuration in which air is blown to the surface of the low stretchable continuous sheet 9A by a cooling fan may be used. In addition, the cooling unit 30 is not provided, and the low extensibility continuous sheet 9A is naturally cooled by the ambient temperature (room temperature) by increasing the conveyance distance between the drying unit 20 and the sheet member joining unit 50 in the production line LM. You may do it. However, the provision of the cooling unit 30 makes it possible to efficiently cool the low-extension continuous sheet 9A, thereby facilitating fixing of the ink. Moreover, since the section (conveyance distance) required for cooling can be shortened, the production line LM can be configured compactly.

(Inspection unit 40)
Subsequently, the image quality of the image G printed on the low extensibility continuous sheet 9A is inspected by the inspection unit 40 (inspection process). FIG. 12 is a side view illustrating the configuration of the inspection unit 40. The inspection unit 40 includes an imaging device 41, an illumination device 42, an imaging control unit 43, and a display unit 44.

  The imaging device 41 is disposed at a position facing the printing surface of the low-extension continuous sheet 9A, and images (scans) the image G printed on the surface in the process of transporting the low-extension continuous sheet 9A. As the imaging device 41, for example, a CCD camera or a CMOS camera is used. The illumination device 42 is a light source that applies light to the printing surface of the low-extension continuous sheet 9 </ b> A when the image G is captured. Note that the imaging device 41 and the illumination device 42 may be integrally configured. Further, a plurality of imaging devices 41 may be provided so that each can capture a different area or an overlapping area of the image G. The imaging control unit 43 controls the operations of the imaging device 41 and the illumination device 42 to capture the image G and causes the display unit 44 to display the captured image (scanned image). The scanned image displayed on the display unit 44 can be appropriately confirmed visually by an inspector or the like. In the present embodiment, the low-extension continuous sheet 9A is conveyed at a relatively high speed. However, the imaging controller 43 appropriately controls the brightness of illumination and the resolution at the time of imaging according to the conveyance speed. Even during the conveying operation of the extensible continuous sheet 9A, the state of the image G can be scanned clearly.

  In addition, the imaging control unit 43 determines whether or not the image quality of the captured image G satisfies a predetermined standard, and issues a warning (alarm) if necessary, or the conveyance operation of the low-extension continuous sheet 9A. The processing such as stopping is performed. More specifically, by acquiring and analyzing density and lightness information for each pixel of the scan image, printing misalignment, foreign matter contamination, ink dot omission, and presence / absence of stains in the image G are detected. Then, when the detection result is compared with a predetermined reference (for example, the occurrence rate of missing dots or the degree of displacement of the printing position), and it is determined that the image quality of the image G is lower than the image quality set in the reference, In conjunction with the transport mechanism CV, the print control unit 14, etc., the transport speed of the low-extension continuous sheet 9A is changed or the printing operation is stopped.

  By automatically inspecting the printed image during the conveying operation of the low-extension continuous sheet 9A, the burden on the inspector and the inspection time can be reduced, and if a defect occurs, it can be dealt with promptly. become. Further, by inspecting the image G in-line on the production line LM, a sheet member on which an image with a good image quality is printed can be efficiently manufactured. In particular, in this embodiment, after the image G is printed on the low-extension continuous sheet 9A, the ink is firmly fixed on the low-extension continuous sheet 9A by a contact process (ink drying process) or a cooling process. Therefore, it is difficult for ink bleeding and image fading to occur in the subsequent steps. Therefore, it is possible to accurately determine the image quality of the image G by performing inspection at least downstream of the drying unit 20 in the transport direction (MD direction). From the viewpoint of ink fixability, the inspection unit 40 is preferably provided on the downstream side in the MD direction of the cooling unit 30 (see FIG. 4), but the inspection unit 40 is between the drying unit 20 and the cooling unit 30. May be provided.

(Sheet member joint 50)
The low stretchable continuous sheet 9A on which the image G has been printed and the ink has been dried is joined to the stretchable continuous sheet 8A in the thickness direction in the sheet member joining portion 50 (joining step). The sheet member joint portion 50 of the present embodiment includes a transport mechanism 51 for the stretchable continuous sheet 8A, a transport mechanism 52 for the low-extension continuous sheet 9A, and an ultrasonic welding device 55 (see FIG. 4).

  The transport mechanism 51 (hereinafter, also simply referred to as “transport mechanism 51”) of the stretchable continuous sheet 8A has a pair of nip rolls 51R and 51R that rotate around a rotation axis along the CD direction, for example. Then, the stretchable continuous sheet 8A continuously conveyed from the upstream side is driven and rotated while the pair of nip rolls 51R and 51R are sandwiched between the outer peripheral surfaces of each other, whereby the stretchable continuous sheet 8A is transferred to the ultrasonic welding device 55. Send it out. Here, the nip roll 51R rotates at a peripheral speed value V51R (m / min), and conveys the stretchable continuous sheet 8A.

  On the other hand, the transport mechanism 52 (hereinafter, also simply referred to as “transport mechanism 52”) of the low-extension continuous sheet 9A includes, for example, a transport roller 52R that rotates about a rotation axis along the CD direction. And the low-extension continuous sheet 9A is rotated to the ultrasonic welding device 55 by the drive roller 52R being driven and rotated while being in contact with the outer peripheral surface of the low-extension continuous sheet 9A continuously conveyed from the upstream side in the MD direction. Send it out. Here, the conveyance roller 52R rotates at a peripheral speed value V52R (m / min) and conveys the low-extension continuous sheet 9A. The peripheral speed value V52R of the transport roller 52R is set to a value that is double the expansion magnification of the peripheral speed value V51R (m / min) of the nip roll 51R (transport mechanism 51).

  The ultrasonic welding device 55 includes an ultrasonic horn 55h that is a horn portion having a vibration surface that vibrates ultrasonically, and an anvil roller 55a that is a roller portion that receives ultrasonic vibration of the vibration surface of the ultrasonic horn 55h on the outer peripheral surface. Have. The anvil roller 55a 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. The stretchable continuous sheet 8A sent from the transport mechanism 51 is wound around the outer peripheral surface of the anvil roller 55a at a predetermined winding angle (for example, 45 ° or more) with almost no relative slip with respect to the outer peripheral surface. Further, the low-extension continuous sheet 9A sent from the transport mechanism 52 is wound on the outer peripheral surface of the anvil roller 55a in a state of being overlapped with the stretchable continuous sheet 8A in the thickness direction.

  The anvil roller 55a rotates at a circumferential speed V55a (m / min) that is substantially the same as the circumferential speed value V52R of the transport roller 52R. Therefore, the low-stretch continuous sheet 9A passes through the position of the ultrasonic horn 55h in a state where it is not stretched, in other words, a state where the low-stretch continuous sheet 9A is properly stretched so as not to be plastically deformed. On the other hand, the stretchable continuous sheet 8A passes through the position of the ultrasonic horn 55h in a state where the stretchable sheet 8A is stretched from the natural length state to the length of the stretch magnification. Then, the ultrasonic vibration energy is input from the vibration surface of the ultrasonic horn 55h to the stretchable continuous sheet 8A and the low stretchable continuous sheet 9A that are superposed in such a state, so that the input portion generates heat. It melts, both sheets are welded with a predetermined joining pattern, and the exterior continuous sheet 7A is generated.

  In this embodiment, as shown in FIG. 4, the low stretchability from the drying unit 20 to the ultrasonic welding device 55 is less than the transport distance of the stretchable continuous sheet 8 </ b> A from the nip roll 51 </ b> R to the ultrasonic welding device 55. The production line LM is configured such that the conveyance distance of the continuous sheet 9A is longer. In other words, the distance at which the low stretchable continuous sheet 9A is transported from the drying to the joining is longer than the distance at which the stretchable continuous sheet 8A is transported while being stretched. The low stretchable continuous sheet 9 </ b> A whose temperature is high by contacting with the heating gas in the drying unit 20 is transported through a sufficiently long transport path so that the temperature reaches the ultrasonic welding device 55. descend. Thereby, when the stretchable continuous sheet 8A and the low stretchable continuous sheet 9A are overlaid on the anvil roller 55a, the stretchability of the thermoplastic elastomer constituting the stretchable continuous sheet 8A by the heat of the low stretchable continuous sheet 9A. Is suppressed from being lost. Furthermore, in this embodiment, since the low extensibility continuous sheet 9A is cooled by the cooling unit 30, it is easier to suppress the application of heat to the stretchable continuous sheet 8A.

In this embodiment, the stretchable continuous sheet 8A is bonded to the surface opposite to the printing surface (the surface on which ink droplets are ejected) of the low stretchable continuous sheet 9A (see FIG. 4). Thereby, poor welding due to ink can be suppressed, and the bonding strength between the stretchable continuous sheet 8A and the low stretchable continuous sheet 9A can be kept strong. The printing surface of the low-stretch continuous sheet 9A is arranged on the opposite side of the stretchable continuous sheet 8A, so that the printing surface of the low-stretch continuous sheet 9A is the non-skin side of the outer sheet 7 of the diaper 1, that is, It is arranged on the outermost surface (outermost surface) of the diaper 1 (see FIG. 3). Thereby, the image G of the exterior sheet 7 of the diaper 1 can be visually recognized in a colorful manner. Since the image G is firmly fixed on the sheet member and has good friction resistance, the image G is hardly deteriorated even when it is formed on the outermost surface of the diaper 1.

  Further, as shown in FIG. 4, when the stretchable continuous sheet 8A and the low stretchable continuous sheet 9A are superposed on the outer peripheral surface of the anvil roller 55a, the low stretchable continuous sheet 9A is set to the inner side (anvil roller 55a side). The elastic continuous sheet 8A is on the outside (the ultrasonic horn 55h side). Thereby, since the ultrasonic horn 55h does not contact the printing surface of the low-extension continuous sheet 9A, it is possible to suppress the occurrence of ink contamination and poor welding of the ultrasonic horn 55h. At that time, the printing surface side on which the image G is formed by the low-extension continuous sheet 9A comes into contact with the outer peripheral surface of the anvil roller 55a. In this embodiment, the drying process (contact process) and the cooling process after the image G printing are performed. Since the ink is dried and firmly fixed on the sheet member, the anvil roller 55a is not easily contaminated by the ink.

  FIG. 13 is a process explanatory diagram from the generation of the exterior continuous sheet 7A to the completion of the diaper 1. The production line LM forms an opening in the exterior continuous sheet 7A that serves as a leg-hole opening HL (see FIG. 1). This opening is formed by being punched from the exterior continuous sheet 7A by an annular cutter blade (not shown). Next, the exterior continuous sheet 7A that has been conveyed in the stretched state is contracted in the MD direction. Thereby, wrinkles are formed on the outer surface of the exterior continuous sheet 7A. Next, the absorptive main body 3 is attached between the leg openings HL of the exterior continuous sheet 7A, and the exterior continuous sheet 7A is folded in two. An end seal portion (end portion 7eW in FIG. 1) is formed by welding in the CD direction from the leg opening HL of the exterior continuous sheet 7A folded in half, and the exterior continuous sheet 7A is divided and separated by the end seal portion. Part becomes diaper 1.

  In addition, in the production line LM, the process of heating the exterior continuous sheet 7A is not provided on the downstream side of the conveyance from the sheet member joint 50. Therefore, excessive heat is not applied to the stretchable sheet 8, and the loss of stretchability of the thermoplastic elastomer constituting the stretchable sheet 8 is suppressed. Thereby, the exterior continuous sheet 7A (diaper 1) can maintain good stretchability.

=== 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, a so-called line printer type in which a head unit is fixed is used as an inkjet printing apparatus. However, a serial type inkjet in which a head having a plurality of nozzles arranged in the MD direction reciprocates in the CD direction. A printing device may be used.

  In the above-described embodiment, the low-extension continuous sheet 9A is a printing medium. However, the printing medium is not limited to this, and inkjet printing is performed on a printing medium (for example, a woven cloth) other than a nonwoven fabric. It may be done. Moreover, although the sheet | seat (low-extension continuous sheet 9A) which comprises the underpants type diaper 1 was a to-be-printed medium, with respect to the sheet | seat which comprises other absorbent articles (for example, sanitary napkins, an incontinence pad, etc.) Ink jet printing may be performed.

  In the production line LM described in the above-described embodiment, a step of heating the low-extension continuous sheet 9A may be provided before printing on the low-extension continuous sheet 9A by the printing unit 10. By heating the low-extension continuous sheet 9A before printing, the gaps between the fibers of the low-extension continuous sheet 9A are expanded, and ink droplets that land on the surface of the low-extension continuous sheet 9A pass through the gaps. It becomes easy and it becomes easy to osmose | permeate the inside of the low extensibility continuous sheet 9A. Thereby, since it becomes difficult for ink to remain on the surface of the low-extension continuous sheet 9A, the friction resistance of the image G can be improved. Further, since the gaps are widened, the heated air can easily flow through the thickness direction of the low-extension continuous sheet 9A in the drying step after printing, and the drying of the ink can be promoted. For example, it is possible to efficiently heat the low extensibility continuous sheet 9A by providing a heater on a conveyance roller or the like constituting the conveyance mechanism CV on the upstream side in the conveyance direction of the printing unit 10. At that time, the temperature of the low-extension continuous sheet 9A can be made uniform by heating the back side and the front side of the low-extension continuous sheet 9A.

  Furthermore, heating before printing may be performed stepwise. In other words, a preheating step may be provided as a pre-stage of the pre-printing heating step. By performing stepwise heating, a rapid temperature change of the low-extension continuous sheet 9A can be suppressed.

1 disposable diapers (absorbent articles, diapers),
3 Absorbent body, 3c Absorbent core,
4 Top sheet,
5 Leak-proof sheet,
7 exterior sheet, 7A exterior continuous sheet,
7f ventral side, 7b dorsal side, 7c crotch, 7eW end,
8 inner layer sheet (elastic sheet), 8A elastic continuous sheet,
9 outer layer sheet (low extensibility sheet), 9A low extensibility continuous sheet,
10 Printing department,
12 head units, 121 heads,
13 transport roller, 14 print control unit,
20 Drying part (contact part),
21 Linear conveying type drying equipment,
211 drying chamber, 212 transport support roller, 213 air outlet, 214 pressure chamber,
231 opening, 232 restrictor, 233 rectifier, 23h heated air supply hole,
25 drum-type drying equipment,
25A first drum dryer, 25B second drum dryer,
251A first drum drying chamber, 252A first drum,
251B second drum drying chamber, 252B second drum,
253 air outlet, 254 pressure chamber, 256 suction port,
271 metal plate, 272 mesh member,
30 cooling section,
40 Inspection Department,
41 imaging device, 42 lighting device, 43 imaging control unit, 44 display unit,
50 sheet member joint,
51 transport mechanism, 51R nip roll,
52 transport mechanism, 52R transport roller,
55 Ultrasonic welding equipment,
55a anvil roller (roller part), 55h ultrasonic horn (horn part),
LM production line,
CV transport mechanism,
Nz nozzle

Claims (11)

A composite sheet manufacturing method for manufacturing a composite sheet having a stretchable sheet made of a nonwoven fabric according to an absorbent article and a low stretchable sheet made of a nonwoven fabric that is less stretchable than the stretchable sheet,
A printing step of ejecting water-based ink droplets toward the low extensible sheet to print an image on the surface of the low extensible sheet;
A contact step of bringing heated air into contact with the low-extension sheet on which the image is printed;
After the contacting step, a joining step of joining the stretchable sheet in an elongated state to the low stretchable sheet;
Have
After the joining step, there is no step of heating the low extensible sheet and the stretchable sheet . The composite sheet manufacturing method according to claim 1,
In the contacting step, the heated air flows through the low-extensible sheet in the thickness direction, and the composite sheet manufacturing method is characterized in that: It is a composite sheet manufacturing method of Claim 2, Comprising:
The method for producing a composite sheet, wherein the heated air flows from a surface on which the image is printed toward a surface on the other side in the thickness direction of the low-extension sheet. It is a composite sheet manufacturing method in any one of Claims 1-3,
In the contacting step, the sheet is conveyed by rotating the drum while holding the low-extension sheet on the outer peripheral surface of the drum, and the heated air is supplied to the air holes formed in the outer peripheral surface. The composite sheet manufacturing method characterized by making it pass. A composite sheet manufacturing method according to any one of claims 1 to 4,
Between the contact step and the joining step,
It has a cooling process which cools the said low extensibility sheet | seat, The composite sheet manufacturing method characterized by the above-mentioned. It is a composite sheet manufacturing method in any one of Claims 1-5,
Between the contact step and the joining step,
A composite sheet manufacturing method comprising an inspection step of inspecting an image quality of an image printed on the low-extensible sheet. It is a composite sheet manufacturing method in any one of Claims 1-6,
The composite sheet manufacturing method, wherein the stretchable sheet is bonded to a surface of the low-extensible sheet opposite to the surface on which the image is printed. It is a composite sheet manufacturing method in any one of Claims 1-7,
The low extensible sheet and the stretchable sheet are joined 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. For the low extensible sheet and the stretchable sheet superimposed on each other on the outer peripheral surface of the roller part, it is performed by introducing ultrasonic vibration from the horn part,
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. It is a composite sheet manufacturing method in any one of Claims 1-8,
A method for producing a composite sheet, wherein a surface of the low-extensible sheet on which the image is printed is disposed on an outermost surface of the absorbent article. It is a composite sheet manufacturing method in any one of Claims 1-9 ,
The distance that the low-extensible sheet is conveyed after the contact step and before it is joined to the elastic sheet is longer than the distance that the elastic sheet is conveyed while being stretched. A composite sheet manufacturing method. A composite sheet manufacturing apparatus that manufactures a composite sheet having a stretchable sheet made of a nonwoven fabric according to an absorbent article and a low stretchable sheet made of a nonwoven fabric that is less stretchable than the stretchable sheet,
A printing unit that discharges water-based ink droplets toward the low-extension sheet and prints an image on the surface of the low-extension sheet;
A contact portion for bringing heated air into contact with the low stretch sheet on which the image is printed;
A sheet member joining portion that joins the stretchable sheet in an elongated state to the low stretchable sheet after contacting heated air;
Have
The composite sheet manufacturing apparatus , wherein the low-extensible sheet and the stretchable sheet are not heated after the joining by the sheet member joining portion .

Images