Coating method and coating apparatus

Abstract

To provide a technology which can prevent a hot melt adhesive from being applied to a designed non-application range.SOLUTION: In an application method, a hot melt adhesive is intermittently applied from a coating gun to an object to be coated (coated object) transported in a given direction. The coating gun has a discharge port which discharges the hot melt adhesive. The application method includes: a first step in which the discharge port is placed in contact with the coated object in an application state where the hot melt adhesive is applied to the coated object; and a second step in which the discharge port is separated from the coated object in the application state.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a coating method and a coating apparatus.

Background Art

[0002] In the manufacturing process of absorbent articles such as disposable diapers, urine pads, and sanitary products, a hot melt adhesive is intermittently applied to an object to be coated such as a sheet material conveyed in a certain direction (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The hot melt adhesive is applied from a coating gun to the object to be coated in a state where the solid raw material is heated and melted. The hot melt adhesive is applied with the discharge port of the coating gun in contact with the object to be coated. Since the hot melt adhesive has a high viscosity even in a melted state, there is a risk that the hot melt adhesive that cannot be completely placed on the sheet material will accumulate on the downstream side in the conveyance direction of the discharge port of the coating gun. When attempting to apply the hot melt adhesive intermittently, if the hot melt adhesive accumulates on the downstream side in the conveyance direction of the discharge port, a trailing phenomenon will occur where the coating gun drags the accumulated hot melt adhesive, and in terms of design, the hot melt adhesive will be applied even to the non-application range where the hot melt adhesive is not supposed to be applied.

[0005] An object of the present invention is to provide a technique that can prevent the hot melt adhesive from being applied to a non-application range in terms of design.

Means for Solving the Problems

[0006] In order to solve the above problems, in the present invention, a step of separating the discharge port from the workpiece to be coated is provided in the state where the hot melt adhesive is applied.

[0007] Specifically, the present invention is a coating method for intermittently applying a hot melt adhesive from a coating gun to a workpiece to be coated that is conveyed in a certain direction. The coating gun has a discharge port for discharging the hot melt adhesive. In the coating state where the hot melt adhesive is applied to the workpiece to be coated, the method includes a first step of bringing the discharge port into contact with the workpiece to be coated, and a second step of separating the discharge port from the workpiece to be coated in the coating state.

[0008] In the above coating method, a roller that rotates in the conveying direction of the workpiece to be coated in synchronization with the conveying speed of the workpiece to be coated is arranged below the workpiece to be coated and on the upstream side of the discharge port. The roller has a circumferential portion and a flat portion. In the first step, the discharge port is brought into contact with the workpiece to be coated by causing the workpiece to be coated to follow the circumferential portion, and in the second step, the workpiece to be coated may be separated from the discharge port by causing the workpiece to be coated to follow the flat portion.

[0009] In the above coating method, a roller that rotates in the conveying direction of the workpiece to be coated in synchronization with the conveying speed of the workpiece to be coated is arranged above the workpiece to be coated and on the upstream side of the discharge port , the The radius of the circumferential portion is longer than the distance from the rotation center of the roller to the workpiece to be coated In the first step, the discharge port is brought into contact with the workpiece to be coated by making the roller and the workpiece to be coated non-contact, and in the second step, the workpiece to be coated may be separated from the discharge port by pressing down the workpiece to be coated by the circumferential portion.

[0010] In the above coating method, a roller that rotates in the conveying direction of the workpiece to be coated in synchronization with the conveying speed of the workpiece to be coated is arranged so as to face the discharge port on the lower side of the workpiece to be coated. The roller has a convex portion and a concave portion. In the first step, the convex portionBy facing the discharge port, the discharge port may be brought into contact with the workpiece to be coated, and in the second step, by facing the recess with the discharge port, the workpiece to be coated may be separated from the discharge port.

[0011] In the above coating method, a lifting device for lifting and lowering the coating gun in the vertical direction is arranged. In the first step, the discharge port is brought into contact with the workpiece to be coated by lowering the coating gun, and in the second step, the workpiece to be coated may be separated from the discharge port by raising the coating gun.

[0012] Further, the present invention is a coating method for intermittently coating a hot melt adhesive from a coating gun onto a workpiece to be coated that is conveyed in a certain direction. The coating gun has a discharge port for discharging the hot melt adhesive. In a coating state where the hot melt adhesive is applied to the workpiece to be coated, a first step of bringing the discharge port into contact with the workpiece to be coated, and a second step of filtering the hot melt adhesive accumulated on the downstream side of the discharge port by applying pressure to the workpiece to be coated from below may be included.

[0013] In the above coating method, a roller that can move up and down is arranged below the workpiece to be coated and on the downstream side of the discharge port. The roller rotates in the conveying direction of the workpiece to be coated in synchronization with the conveying speed of the workpiece to be coated. In the first step, the roller is in contact with the workpiece to be coated at a predetermined position. In the second step, by contacting the workpiece to be coated with the roller above the predetermined position, pressure is applied to the workpiece to be coated, and the hot melt adhesive accumulated on the downstream side of the discharge port is filtered. The coating method may include a third step of separating the workpiece to be coated from the discharge port by lowering the roller in the coating state.

[0014] In the above coating method, a roller that rotates in the conveyance direction of the workpiece to be coated in synchronization with the conveyance speed of the workpiece to be coated is disposed below the workpiece to be coated and on the downstream side of the discharge port. The roller has a circumferential portion corresponding to the length of the application range of the hot melt adhesive to the workpiece to be coated, an enlarged diameter portion having a diameter larger than that of the circumferential portion, which applies pressure to the workpiece to be coated and filters the hot melt adhesive accumulated on the downstream side of the discharge port, and a reduced diameter portion having a diameter smaller than that of the circumferential portion, which is disposed so as to face the workpiece to be coated after the enlarged diameter portion. In the first step, the discharge port is brought into contact with the workpiece to be coated by causing the workpiece to be coated to follow the circumferential portion. In the second step, pressure is applied to the workpiece to be coated by the enlarged diameter portion to filter the hot melt adhesive accumulated on the downstream side of the discharge port. The coating method may include a third step of separating the workpiece to be coated from the discharge port by facing the reduced diameter portion toward the workpiece to be coated in the coating state.

[0015] In the above coating method, in the second step, compressed air may be applied to the workpiece to be coated from below the workpiece to be coated to filter the hot melt adhesive.

[0016] In the above coating method, the workpiece to be coated is a sheet material for absorbent articles, and the hot melt adhesive may be blended with a material that changes color when it comes into contact with excrement.

[0017] Further, the present invention can be grasped from the side of the coating apparatus. For example, the present invention is a coating apparatus that intermittently applies a hot melt adhesive from a coating gun to a workpiece to be coated that is conveyed in a certain direction, the coating gun having a discharge port for discharging the hot melt adhesive, the coating gun bringing the discharge port into contact with the workpiece to be coated in a coating state where the hot melt adhesive is applied to the workpiece to be coated, and a separating means for separating the discharge port from the workpiece to be coated in the coating state.

[0018] Further, the present invention is a coating apparatus for intermittently applying a hot melt adhesive from a coating gun to a workpiece to be coated that is conveyed in a certain direction, the coating gun having a discharge port for discharging the hot melt adhesive, the coating gun being configured to bring the discharge port into contact with the workpiece in a coating state where the hot melt adhesive is applied to the workpiece, and filtering means for filtering the hot melt adhesive accumulated on the downstream side of the discharge port by applying pressure to the workpiece from below in the coating state.

Advantages of the Invention

[0019] According to the present invention, it is possible to prevent the hot melt adhesive from being applied to a non-coated range in the design.

Brief Description of the Drawings

[0020]

Figure 1

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[0021] Embodiments of the present invention will be described below with reference to the drawings. Note that the configurations of the following embodiments are merely examples, and the present invention is not limited to the configurations of these embodiments.

[0022] <Overview of Coating Method> The coating method according to the present embodiment is a method of intermittently applying a hot melt adhesive from a coating gun to a workpiece to be coated that is conveyed in a certain direction. Examples of the workpiece to be coated include sheet materials used for absorbent articles such as disposable diapers, urine pads, and sanitary products. In a manufacturing line for manufacturing absorbent articles, a hot melt adhesive is applied to a sheet material for absorbent articles that is conveyed in a certain direction. The hot melt adhesive is intermittently applied to the sheet material so as to be applied within a designed coating range (hereinafter referred to as the "coating range") and not applied within a designed non-coating range (hereinafter referred to as the "non-coating range"). The coating range and the non- The coating range is continuous in the conveyance direction of the sheet material. When the coating range of the sheet material passes under the coating gun, the hot melt adhesive is discharged from the coating gun, and when the non-coating range of the sheet material passes under the coating gun, the hot melt adhesive is not discharged from the coating gun. Thereby, the hot melt adhesive is intermittently applied to the sheet material conveyed in a certain direction.

[0023] Further, in the coating method according to the present embodiment, in the coating state where the hot melt adhesive is applied to the sheet material, the discharge port of the coating gun is brought into contact with the sheet material. In contrast, when the hot melt adhesive is applied without bringing the discharge port of the coating gun into contact with the sheet material, the hot melt adhesive is applied by spraying, and when the hot melt adhesive is applied intermittently, the hot melt adhesive cannot be applied cleanly at the end portion. Therefore, when it is necessary to apply the hot melt adhesive intermittently (for example, when it is necessary to provide a non-adhesive area or when applying a hot melt adhesive containing a coloring substance for forming an indicator), it is preferable to bring the coating gun into contact with the sheet material as in the coating method according to the present embodiment.

[0024] Further, in the coating method according to the present embodiment, the hot melt adhesive is applied from the coating gun to the sheet material in a state where the solid raw material is heated to about 140°C to 160°C and melted. Since the hot melt adhesive has a high viscosity even in the melted state, there is a risk that the hot melt adhesive that cannot be completely loaded on the sheet material will accumulate on the downstream side in the conveyance direction of the discharge port of the coating gun.

[0025] FIG. 1 is a schematic diagram showing a coating method according to a comparative example. The upper part of FIG. 1 is a schematic diagram of the sheet material S, which is the object to be coated, viewed from above, and the lower part of FIG. 1 is a schematic diagram of the sheet material S viewed from the side. The sheet material S is conveyed in the direction indicated by arrow A1 in FIG. 1 by a roller R100 that rotates in the direction indicated by arrow A2 in FIG. 1. The coating gun G is supplied with the raw material of the hot melt adhesive H heated to about 140°C to 160°C from a supply device (not shown) by a pump, and the coating gun G can discharge the hot melt adhesive H from a discharge port N provided at the tip. Further, by switching the pump of the supply device between an operating state and a non-operating state, it is possible to switch between a discharge state where the hot melt adhesive H is discharged from the discharge port N and a non-discharge state where the hot melt adhesive H is not discharged from the discharge port N. Further, in the comparative example, a contact-type coating gun G that constantly contacts the discharge port N with the sheet material is adopted.

[0026] In this comparative example, the range B shown in FIG. 1 is the designed application range of the hot melt adhesive H. When the rear end of the application range B passes through the discharge port N, the hot melt adhesive H is in a non-discharging state. However, there is a trailing phenomenon where the coating gun G drags the hot melt adhesive H accumulated on the downstream side in the conveying direction of the discharge port N, and the hot melt adhesive H is also applied to the non-application range. Thus, when the hot melt adhesive H is intermittently applied with the discharge port N of the coating gun G always in contact with the sheet material S, a trailing phenomenon occurs where the coating gun G drags the hot melt adhesive H, and the hot melt adhesive H is also applied to the non-application range. In absorbent articles, it is not preferable that adhesiveness is exhibited in the non-application range where non-adhesion is desired. Although it is conceivable to lower the viscosity of the hot melt adhesive H by raising the temperature of the hot melt adhesive H above 160°C to suppress the occurrence of trailing, if the hot melt adhesive H is heated above 160°C, there is a risk that the performance will change, which is not preferable.

[0027] <Embodiment 1> First, the coating method according to Embodiment 1 will be described. In the coating method according to this embodiment, the discharge port of the coating gun is separated from the sheet material in the coating state where the hot melt adhesive is applied to the sheet material. Thereby, it is possible to prevent the hot melt adhesive from accumulating on the downstream side in the conveying direction of the discharge port. The coating method according to this embodiment can prevent the coating gun from dragging the hot melt adhesive in the non-coating state of the hot melt adhesive and prevent the hot melt adhesive from being applied to the designed non-application range. The coating gun can prevent dragging the hot melt adhesive and prevent the hot melt adhesive from being applied to the designed non-application range.

[0028] FIG. 2 is a flowchart showing an outline of the coating method according to the present embodiment. In the coating method according to the present embodiment, first, in a coating state where the hot melt adhesive H is applied to the sheet material, the discharge port is brought into contact with the sheet material (step S101, an example of the "first step" referred to in the present application). Next, in the coating state of the hot melt adhesive H, the discharge port is separated from the sheet material (step S102, an example of the "second step" referred to in the present application). The coating method according to the present embodiment prevents the hot melt adhesive H from accumulating on the downstream side in the conveyance direction of the discharge port by repeatedly executing step S101 and step S102 once or a plurality of times. After repeatedly executing step S101 and step S102 once or a plurality of times, the coating method according to the present embodiment can intermittently apply the hot melt adhesive H to the sheet material conveyed in a certain direction by setting the hot melt adhesive H to a non-coated state.

[0029] Next, based on FIGS. 3 to 8, the coating method according to the present embodiment will be described in more detail. In the present embodiment, six specific examples of Examples 1 to 6 are illustrated. As shown in FIGS. 3 to 8, in the present embodiment, the coating gun G has a discharge port N for discharging the hot melt adhesive H. The raw material of the hot melt adhesive H heated to about 140°C to 160°C is supplied to the coating gun G by a pump from a supply device (not shown). Also, similar to the above-described comparative example, the discharge state and the non-discharge state of the hot melt adhesive H can be switched by switching the pump of the supply device between an operating state and a non-operating state. Further, in each of the embodiments shown in FIGS. 3 to 8, the sheet material is conveyed in the direction indicated by the arrow A1 in each figure.

[0030] <Example 1> Based on FIGS. 3(a) and 3(b), the coating method according to Example 1 will be described. FIGS. 3(a) and 3(b) are schematic diagrams for explaining the coating method according to this example. The coating apparatus used in the coating method according to this example includes a coating gun G and a roller R1 (an example of the "spacing means" referred to in the present application). The roller R1 rotates in the conveying direction (the direction indicated by arrow A2) in synchronization with the conveying speed of the sheet material S. The coating method according to this example spaces the discharge port N from the sheet material S by the roller R1 disposed on the lower side of the sheet material S and on the upstream side of the discharge port N.

[0031] FIG. 3(a) is a schematic diagram showing a state where the discharge port N is in contact with the sheet material S in the coating state of the hot melt adhesive H, and FIG. 3(b) is a schematic diagram showing a state where the discharge port N is spaced from the sheet material S in the coating state of the hot melt adhesive H. The roller R1 has a circumferential portion C1 and a flat portion C2. In the coating method according to this example, the discharge port N is brought into contact with the sheet material S by causing the sheet material to follow the circumferential portion C1 in the coating state, and the sheet material S is spaced from the discharge port N by causing the sheet material S to follow the flat portion C2 in the coating state. Thereby, in the coating state, bringing the discharge port N into contact with the sheet material S and spacing the sheet material S from the discharge port N can be performed once or a plurality of times, and accumulation of the hot melt adhesive H on the downstream side in the conveying direction of the discharge port can be prevented.

[0032] <Example 2> Based on FIGS. 4(a) and 4(b), the coating method according to Example 2 will be described. FIGS. 4(a) and 4(b) are schematic diagrams for explaining the coating method according to this example. The coating apparatus used in the coating method according to this example includes a coating gun G and a roller R2 (an example of the "spacing means" referred to in the present application). The roller R2 rotates in the conveying direction (the direction indicated by arrow A2) in synchronization with the conveying speed of the sheet material S. The coating method according to this example spaces the discharge port N from the sheet material S by the roller R2 disposed on the upper side of the sheet material S and on the upstream side of the discharge port N.

[0033] FIG. 4(a) shows the discharge port N in contact with the sheet material S in the coating state of the hot melt adhesive H It is a schematic diagram showing the state after causing, and Fig. 4(b) is a schematic diagram showing the state where the discharge port N is separated from the sheet material S in the state of applying the hot melt adhesive H. The roller R2 has a circumferential portion C3, and the radius of the circumferential portion C3 is longer than the distance from the rotation center O of the roller R2 to the sheet material S. In the coating method according to the present embodiment, the discharge port N is brought into contact with the sheet material S by making the roller R2 and the sheet material S non-contact, and the sheet material S is pushed down by the circumferential portion C3 in the coating state to separate the sheet material S from the discharge port N. Thereby, in the coating state, bringing the discharge port N into contact with the sheet material S and separating the sheet material S from the discharge port N can be performed once or a plurality of times, and it is possible to prevent the hot melt adhesive H from accumulating on the downstream side in the conveyance direction of the discharge port.

[0034] <Example 3> Based on Figs. 5(a) and (b), the coating method according to Example 3 will be described. Figs. 5(a) and (b) are schematic diagrams for explaining the coating method according to the present embodiment. The coating apparatus used in the coating method according to the present embodiment includes a coating gun G and a roller R3 (an example of the "separating means" referred to in the present application). The roller R3 is rotating in the conveyance direction (the direction indicated by the arrow A2) in synchronization with the conveyance speed of the sheet material S. The coating method according to the present embodiment separates the discharge port N from the sheet material S by the roller R3 disposed so as to face the discharge port N below the sheet material S.

[0035] Fig. 5(a) is a schematic diagram showing the state where the discharge port N is in contact with the sheet material S in the state of applying the hot melt adhesive H, and Fig. 5(b) is a schematic diagram showing the state where the discharge port N is separated from the sheet material S in the state of applying the hot melt adhesive H. The roller R3 has a convex portion D1 and a concave portion D2. In the coating method according to the present embodiment, in the coating state convex portionBy facing D1 towards the discharge port N, the discharge port N is brought into contact with the sheet material S, and by facing the recess D2 towards the discharge port N in the coating state, the sheet material S is separated from the discharge port N. As a result, in the coating state, bringing the discharge port N into contact with the sheet material S and separating the sheet material S from the discharge port N can be performed once or a plurality of times, and it is possible to prevent the hot melt adhesive H from accumulating on the downstream side in the conveyance direction of the discharge port.

[0036] <Example 4> Based on FIGS. 6(a) and 6(b), the coating method according to Example 4 will be described. FIGS. 6(a) and 6(b) are schematic diagrams for explaining the coating method according to this example. The coating apparatus used in the coating method according to this example includes a coating gun G and a roller R4 (an example of the "separating means" in the present application). The roller R4 rotates in the conveyance direction (the direction indicated by the arrow A2) in synchronization with the conveyance speed of the sheet material S. In the coating method according to this example, the discharge port N is separated from the sheet material S by the roller R4 disposed on the lower side of the sheet material S and on the upstream side of the discharge port N.

[0037] FIG. 6(a) is a schematic diagram showing a state in which the discharge port N is in contact with the sheet material S in the coating state of the hot melt adhesive H, and FIG. 6(b) is a schematic diagram showing a state in which the discharge port N is separated from the sheet material S in the coating state of the hot melt adhesive H. The roller R4 is configured by combining a first roller R41 and a second roller R42. The first roller R41 and the second roller 42 form the circumferential portion C4 of the roller R4. Further, a separation portion D3 where the circumferential portion C4 is not formed is provided between the first roller R41 and the second roller 42. In the coating method according to this example, the discharge port N is brought into contact with the sheet material S by causing the sheet material to follow the circumferential portion C4 in the coating state, and the sheet material S is separated from the discharge port N by causing the sheet material S to follow the separation portion D3 in the coating state. As a result, in the coating state, bringing the discharge port N into contact with the sheet material S and separating the sheet material S from the discharge port N can be performed once or a plurality of times, and it is possible to prevent the hot melt adhesive H from accumulating on the downstream side in the conveyance direction of the discharge port.

[0038] <Example 5> Based on FIGS. 7(a) and 7(b), the coating method according to Example 5 will be described. FIGS. 7(a) and 7(b) are schematic diagrams for explaining the coating method according to this example. The coating apparatus used in the coating method according to this example includes a coating gun G and a lifting device M1 (an example of the "spacing means" referred to in the present application) for lifting and lowering the coating gun G in the vertical direction. The lifting device M1 has two guide rails L arranged opposite to the driving part M11, and the driving part M11 can drive the coating gun G up and down along the guide rails L. The driving part M11 may be configured to include, for example, a motor or a hydraulic device. In the coating method according to this example, the discharge port N is separated from the sheet material S by lifting the coating gun G by the lifting device M1.

[0039] FIG. 7(a) is a schematic diagram showing a state in which the discharge port N is in contact with the sheet material S in the coating state of the hot melt adhesive H, and FIG. 7(b) is a schematic diagram showing a state in which the discharge port N is separated from the sheet material S in the coating state of the hot melt adhesive H. In the coating method according to this example, the discharge port N is brought into contact with the sheet material S by lowering the coating gun G in the coating state, and the sheet material S is separated from the discharge port N by raising the coating gun G in the coating state. Thereby, in the coating state, bringing the discharge port N into contact with the sheet material S and separating the sheet material S from the discharge port N can be performed once or a plurality of times, and it is possible to prevent the hot melt adhesive H from accumulating on the downstream side in the conveyance direction of the discharge port.

[0040] <Modification Example 1 of Example 5> Based on FIGS. 8(a) and 8(b), the coating method according to Modification 1 of Example 5 will be described. FIGS. 8(a) and 8(b) are schematic diagrams for explaining the coating method according to this modification. The coating apparatus used in the coating method according to this modification includes a coating gun G and a lifting device M20 (an example of the "spacing means" referred to in the present application) for lifting and lowering the coating gun G in the vertical direction. The lifting device M20 is a power cylinder and has a cylinder tube M21, a piston rod M22 provided so as to be able to advance and retreat with respect to the cylinder tube M21, and two guide rails L arranged opposite to each other so as to extend in the vertical direction. The lower end of the piston rod M22 is connected to the coating gun G. A pipe (not shown) is connected to the cylinder tube M21, and by supplying and discharging a liquid such as gas or oil as a power source through the pipe, the piston rod M22 can advance and retreat with respect to the cylinder tube M21. The lifting device M20 can drive the coating gun G up and down along the guide rails L by advancing and retreating the piston rod M22 with respect to the cylinder tube M21. In the coating method according to this modification, the discharge port N is separated from the sheet material S by raising the coating gun G by the lifting device M20.

[0041] FIG. 8(a) is a schematic diagram showing the coating state of the hot melt adhesive H, and FIG. 8(b) is a schematic diagram showing the non - coating state of the hot melt adhesive H. In the coating method according to this modification, the discharge port N is brought into contact with the sheet material S by lowering the coating gun G in the coating state, and the sheet material S is separated from the discharge port N by raising the coating gun G in the non - coating state. Thereby, when switching the hot melt adhesive H from the coating state to the non - coating state, the sheet material S can be separated from the discharge port N.

[0042] <Modification 2 of Example 5> Based on FIGS. 9(a) and 9(b), the coating method according to Modification Example 2 of Example 5 will be described. FIGS. 9(a) and 9(b) are schematic diagrams for explaining the coating method according to this modification example. The coating apparatus used in the coating method according to this modification example includes a coating gun G and a lifting device M30 (an example of the "separating means" referred to in the present application) for lifting and lowering the coating gun G. The lifting device M30 is a power cylinder and has a cylinder tube M31, a piston rod M32 provided so as to be able to advance and retreat with respect to the cylinder tube M31, and an arm M33. The piston rod M32 and the arm M33 are connected by a rotation axis AX1, and the arm M33 is rotatable around the rotation axis AX1 with respect to the piston rod M32. Further, the lower end of the arm M33 is connected to the coating gun G. The coating gun G is rotatable around a rotation axis AX2. A pipe (not shown) is connected to the cylinder tube M 31, and by supplying and discharging a liquid such as gas or oil as a power source through the pipe, the piston rod M32 can advance and retreat with respect to the cylinder tube M31. The lifting device M30 can switch between a state where the discharge port N of the coating gun G is in contact with the sheet material S and a state where the discharge port N of the coating gun G is separated from the sheet material S by advancing and retreating the piston rod M32 with respect to the cylinder tube M31 and rotating the arm M33 and the coating gun G connected thereto.

[0043] FIG. 9(a) is a schematic diagram showing the coating state of the hot melt adhesive H, and FIG. 9(b) is a schematic diagram showing the non-coating state of the hot melt adhesive H. In the coating method according to this modification example, the sheet material S is separated from the discharge port N by rotating the coating gun G downstream in the non-coating state. Thereby, when switching the hot melt adhesive H from the coating state to the non-coating state, the sheet material S can be separated from the discharge port N.

[0044] <Modification Example 3 of Example 5> Based on FIGS. 10(a) and 10(b), the coating method according to Modification Example 3 of Example 5 will be described. FIGS. 10(a) and 10(b) are schematic diagrams for explaining the coating method according to this modification example. The coating apparatus used in the coating method according to this modification example includes a coating gun G and a lifting device M40 (an example of the "spacing means" referred to in the present application) that moves the coating gun G up and down in the vertical direction. The lifting device M40 includes a motor M41, a pinion gear M42 fixed to the rotating shaft of the motor 41, and a rack gear M43 that meshes with the pinion gear M42. The lower end of the rack gear M43 is connected to the coating gun G. The lifting device M40 rotates the pinion gear M42 by driving the motor M41, thereby moving the rack gear M43 up and down in the vertical direction. As a result, the lifting device M40 can drive the coating gun G up and down. In the coating method according to this modification example, the discharge port N is separated from the sheet material S by raising the coating gun G by the lifting device M40.

[0045] FIG. 10(a) is a schematic diagram showing the coating state of the hot melt adhesive H, and FIG. 10(b) is a schematic diagram showing the non-coating state of the hot melt adhesive H. In the coating method according to this modification example, the discharge port N is brought into contact with the sheet material S by lowering the coating gun G in the coating state, and the sheet material S is separated from the discharge port N by raising the coating gun G in the non-coating state. Thereby, when switching the hot melt adhesive H from the coating state to the non-coating state, the sheet material S can be separated from the discharge port N.

[0046] <Example 6> Based on FIGS. 11(a) and 11(b), the coating method according to Example 6 will be described. FIGS. 11(a) and 11(b) are schematic diagrams for explaining the coating method according to this example. The coating apparatus used in the coating method according to this example includes a coating gun G and a suction device M2 (an example of the "spacing means" referred to in the present application) that lowers the coating gun G by sucking the sheet material S. The suction device M2 is disposed at a position opposing the discharge port N below the sheet material S. In the coating method according to this example, the discharge port N is separated from the sheet material S by sucking the sheet material S with the suction device M2.

[0047] FIG. 11(a) is a schematic view showing a state where the discharge port N is in contact with the sheet material S in the state of applying the hot melt adhesive H, and FIG. 11(b) is a schematic view showing a state where the discharge port N is separated from the sheet material S in the state of applying the hot melt adhesive H. In the coating method according to this embodiment, in the coating state, the discharge port N is brought into contact with the sheet material S, and in the coating state, the sheet material S is sucked by the suction device M to separate the sheet material S from the discharge port N. Thereby, in the coating state, bringing the discharge port N into contact with the sheet material S and separating the sheet material S from the discharge port N can be performed once or a plurality of times, and it is possible to prevent the hot melt adhesive H from accumulating on the downstream side in the conveyance direction of the discharge port.

[0048] The coating method according to this embodiment can adopt any of the above-described embodiments. According to the coating method according to each embodiment of this embodiment, it is possible to prevent the hot melt adhesive H from accumulating on the downstream side in the conveyance direction of the discharge port, and to prevent the occurrence of dragging in which the coating gun G drags the hot melt adhesive H, so that it is possible to prevent the hot melt adhesive H from being applied to the non-coating range in the design.

[0049] <Embodiment 2> Next, the coating method according to Embodiment 2 will be described. In the coating method according to this embodiment, in the state of applying the hot melt adhesive H, the hot melt adhesive H accumulated on the downstream side of the discharge port is filtered off. Thereby, it is possible to prevent the hot melt adhesive H from accumulating on the downstream side in the conveyance direction of the discharge port. The coating method according to this embodiment can prevent the coating gun from dragging the hot melt adhesive H in the non-coating state of the hot melt adhesive H, and can prevent the hot melt adhesive H from being applied to the non-coating range in the design.

[0050] FIG. 12 is a flowchart showing an outline of the coating method according to the present embodiment. In the coating method according to the present embodiment, first, the hot melt adhesive H is applied to the sheet material (step S201, an example of the "first step" referred to in the present application). Next, in the state where the hot melt adhesive H is applied, by applying pressure to the sheet material from below, the hot melt adhesive H accumulated on the downstream side of the discharge port is filtered out (step S202, an example of the "second step" referred to in the present application). Next, in the state where the hot melt adhesive H is applied, the sheet material is separated from the discharge port (step S203, an example of the "third step" referred to in the present application). The coating method according to the present embodiment prevents the hot melt adhesive H from accumulating on the downstream side in the conveyance direction of the discharge port by repeatedly executing steps S201 to S203 once or a plurality of times. After repeatedly executing steps S201 to S203 once or a plurality of times, the coating method according to the present embodiment can intermittently apply the hot melt adhesive H to the sheet material conveyed in a certain direction by making the hot melt adhesive H in a non-coated state. Note that step S203 can be omitted.

[0051] Next, based on FIGS. 13 to 15, the coating method according to the present embodiment will be described in more detail. In the present embodiment, three specific examples of Examples 1 to 3 are illustrated. As shown in FIGS. 13 to 15, in the present embodiment, similar to Embodiment 1 above, the coating gun G has a discharge port N for discharging the hot melt adhesive H. Further, in the present embodiment, a contact type coating gun G that brings the discharge port N into contact with the sheet material S in the discharge state is adopted. Also, in each of the embodiments shown in FIGS. 10 to 12, the sheet material is conveyed in the direction indicated by the arrow A1 in each figure.

[0052] <Example 1> Based on FIGS. 13(a) to 13(c), the coating method according to Example 1 will be described. FIGS. 13(a) to 13(c) are schematic diagrams for explaining the coating method according to this example. The upper part of FIGS. 13(a) to 13(c) is a schematic diagram of the sheet material S viewed from above, and the lower part of FIGS. 13(a) to 13(c) is a schematic diagram of the sheet material S viewed from the side. The coating apparatus used in the coating method according to this example includes a coating gun G and a roller R10 (an example of the "filtering means" referred to in the present application). The roller R10 is located below the sheet material S, and the rotation center O is arranged on the downstream side of the discharge port N and is movable up and down. Further, the roller R10 rotates in the conveying direction of the sheet material S (the direction indicated by the arrow A2) in synchronization with the conveying speed of the sheet material S.

[0053] FIG. 13(a) shows the step of applying the hot melt adhesive H. In this step, the roller R10 is in contact with the sheet material S at a predetermined position, and the discharge port N is in contact with the sheet material S. The sheet material S is conveyed downstream in the tangential direction of the circumference of the roller R10 while being in contact with the discharge port N. Note that the predetermined position of the roller R10 in this step is the height at which the sheet material S is in a suitable position with respect to the discharge port N in the state of applying the hot melt adhesive H.

[0054] FIG. 13(b) shows the step of filtering the hot melt adhesive H. In this step, the roller R10 applies pressure to the sheet material S by contacting the sheet material S above a predetermined position, and filters the hot melt adhesive H accumulated on the downstream side of the discharge port N. Thereby, in the state of applying the hot melt adhesive H, the hot melt adhesive H accumulated on the downstream side of the discharge port N can be filtered. Therefore, it is possible to prevent the hot melt adhesive H from accumulating on the downstream side in the conveying direction of the discharge port, and to prevent the hot melt adhesive H from being applied to the non-coating range in the design.

[0055] FIG. 13(c) shows a step of separating the sheet material S from the discharge port N in a state where the hot melt adhesive H is filtered out and the hot melt adhesive H is not applied. In this step, the roller R10 is lowered to separate the sheet material S from the discharge port N. By this step, even when the hot melt adhesive H could not be completely filtered out in the previous step, it is possible to prevent the hot melt adhesive H from accumulating on the downstream side in the conveyance direction of the discharge port, and to prevent the hot melt adhesive H from being applied to the non-application range in the design.

[0056] <Example 2> Based on FIGS. 14(a) to (c), the coating method according to Example 2 will be described. FIGS. 14(a) to (c) are schematic views for explaining the coating method according to this example. The upper part of FIGS. 14(a) to (c) is a schematic view of the sheet material S seen from above, and the lower part of FIGS. 14(a) to (c) is a schematic view of the sheet material S seen from the side. The coating apparatus used in the coating method according to this example includes a coating gun G and a roller R20 (an example of the "filtering means" referred to in the present application). The roller R20 is located below the sheet material S, and the rotation center O is arranged on the downstream side of the discharge port N. Further, the roller 20 rotates in the conveyance direction of the sheet material S (the direction indicated by the arrow A2) in synchronization with the conveyance speed of the sheet material S.

[0057] The roller R20 has a circumferential portion R21, a diameter-expanded portion R22 having a diameter larger than that of the circumferential portion R21, and a diameter-reduced portion R23 having a diameter smaller than that of the circumferential portion R21. The diameter-expanded portion R22 contacts the sheet material S to apply pressure to the sheet material S, and filters out the hot melt adhesive H accumulated on the downstream side of the discharge port N. The distance between the outer circumference of the diameter-expanded portion R22 and the rotation center of the roller R20 is set to a length at which sufficient pressure is applied to the sheet material S. The diameter-reduced portion R23 is arranged so as to face the sheet material S side after the diameter-expanded portion R22. The distance between the outer circumference of the diameter-reduced portion R23 and the rotation center of the roller R20 is set to a length that allows the sheet material S to be separated from the nozzle N in a state where the diameter-reduced portion R23 faces the sheet material S side.

[0058] Figure 14(a) shows the step of applying the hot melt adhesive H. In this step, the discharge port N is brought into contact with the sheet material S by aligning the sheet material S along the circumferential portion R21 of the roller R20. The sheet material S is conveyed downstream in the tangential direction of the circumferential portion R21 while being in contact with the discharge port N.

[0059] Figure 14(b) shows the step of filtering off the hot melt adhesive H. In this step, the enlarged diameter portion R22 is in contact with the sheet material S, and by applying pressure to the sheet material S with the enlarged diameter portion R22, the hot melt adhesive H accumulated on the downstream side of the discharge port N can be filtered off. As a result, in the state of applying the hot melt adhesive H, the hot melt adhesive H accumulated on the downstream side of the discharge port N can be filtered off. Therefore, it is possible to prevent the hot melt adhesive H from accumulating on the downstream side in the conveyance direction of the discharge port, and to prevent the hot melt adhesive H from being applied to the non-application range in the design.

[0060] Figure 14(c) shows the step of separating the sheet material S from the discharge port N in the non-application state of the hot melt adhesive H after filtering off the hot melt adhesive H. In this step, the sheet material S is separated from the discharge port N by directing the reduced diameter portion R23 toward the sheet material S. Even if the hot melt adhesive H could not be completely filtered off in the previous step, this step can prevent the coating gun G from dragging the hot melt adhesive H and prevent the hot melt adhesive H from being applied to the non-application range in the design.

[0061] <Example 3> Based on FIGS. 15(a) to (b), the coating method according to Example 3 will be described. FIGS. 15(a) to (b) are schematic diagrams for explaining the coating method according to this example. The upper part of FIGS. 15(a) to (b) is a schematic diagram of the sheet material S viewed from above, and the lower part of FIGS. 15(a) to (b) is a schematic diagram of the sheet material S viewed from the side. The coating apparatus used in the coating method according to this example includes a coating gun G and a blower device M3 (an example of the "filtering means" referred to in the present application). The blower device M3 is disposed below the sheet material S and blows compressed air toward the downstream side of the discharge port N.

[0062] FIG. 15(a) shows the step of applying the hot melt adhesive H. In this step, the discharge port N is in contact with the sheet material S.

[0063] FIG. 15(b) shows the step of filtering the hot melt adhesive H. In this step, by applying compressed air from the blower M3 to the sheet material S from the lower side of the sheet material S, the hot melt adhesive H accumulated on the downstream side of the discharge port N can be filtered off. Thereby, when switching the hot melt adhesive H from the applied state to the non-applied state, the hot melt adhesive H accumulated on the downstream side of the discharge port N can be filtered off. Therefore, it is possible to prevent the coating gun G from dragging the hot melt adhesive H in the non-applied state, and to prevent the hot melt adhesive H from being applied to the non-applied range in the design.

[0064] The coating method according to the present embodiment can adopt any of the above-described examples. According to the coating method according to each example of the present embodiment, it is possible to prevent the hot melt adhesive H from accumulating on the downstream side in the conveyance direction of the discharge port, and to prevent the occurrence of dragging in which the coating gun G drags the hot melt adhesive H. Therefore, it is possible to prevent the hot melt adhesive H from being applied to the non-applied range in the design.

[0065] Further, in the above embodiment, the hot melt adhesive H may be blended with a material for an indicator that changes color when it comes into contact with excrement. In the absorbent article, the portion where the material for the indicator is applied functions as an indicator that shows the presence or absence of excrement such as urination to the outside. The indicator is provided, for example, by applying the hot melt adhesive H containing the material for the indicator to the skin side of the back sheet. Note that, as the material for the indicator, a moisture detection material, a pH reaction material, or the like is used. According to the coating method according to the present embodiment, the hot melt adhesive H containing this material can be applied to the arrangement region of the indicator, and the hot melt adhesive H can be prevented from being applied to the non-arrangement region of the indicator, so that the indicator can be arranged within the designed range. Thereby, since the indicator can be arranged within the range as designed for the absorbent article, it is possible to prevent the indicator from becoming an obstacle in the design of the absorbent article.

[0066] <Other Embodiments> As described above, the embodiments of the present invention have been described, but the various embodiments described above can be combined as much as possible.

Explanation of Reference Numerals

[0067] A1, A2 ··· Arrow C1, C3, C4 ··· Circumferential Portion C2 ··· Flat Portion G ··· Coating Gun H ··· Hot Melt Adhesive M1, M20, M30, 40 ··· Lifting Device M2 ··· Suction Device M3 ··· Blower N ··· Discharge Port R1, R2, R3, R4, R10, R20, R100 ··· Roller S ··· Sheet Material

Claims

1. A coating method for intermittently applying a hot melt adhesive from a coating gun to a workpiece being conveyed in a certain direction, wherein the coating gun has a discharge port for discharging the hot melt adhesive, in a coating state where the hot melt adhesive is applied to the workpiece, a first step of bringing the discharge port into contact with the workpiece; in the coating state, a second step of separating the discharge port from the workpiece; including the coating state is a state where the hot melt adhesive is discharged from the discharge port, after repeating the first step and the second step once or a plurality of times, a non - coating state where the hot melt adhesive is not discharged from the discharge port is set, so that the hot melt adhesive is applied to the coated area of the workpiece and not applied to the non - coated area of the workpiece, thereby intermittently applying the hot melt adhesive. Coating method.

2. Below the workpiece and on the upstream side of the discharge port, a roller is arranged which rotates in the conveying direction of the workpiece in synchronization with the conveying speed of the workpiece, the roller has a circumferential portion and a flat portion, in the first step, by bringing the workpiece along the circumferential portion, the discharge port is brought into contact with the workpiece, in the second step, by bringing the workpiece along the flat portion, the workpiece is separated from the discharge port. The coating method according to claim 1.

3. Above the workpiece and on the upstream side of the discharge port, a roller is arranged which rotates in the conveying direction of the workpiece in synchronization with the conveying speed of the workpiece, the radius of the circumferential portion of the roller is longer than the distance from the rotation center of the roller to the workpiece, in the first step, by making the roller and the workpiece non - contact, the discharge port is brought into contact with the workpiece, in the second step, by pressing down the workpiece by the circumferential portion, the workpiece is separated from the discharge port. The coating method according to claim 1.

4. A roller is arranged below the workpiece and facing the discharge port, which rotates in the conveying direction of the workpiece in synchronization with the conveying speed of the workpiece, the roller has a convex portion and a concave portion, in the first step, by making the convex portion face the discharge port, the discharge port is brought into contact with the workpiece, In the second step, the concave portion faces the discharge port to separate the workpiece from the discharge port. The coating method according to claim 1.

5. There is a lifting device for lifting the coating gun in the vertical direction. In the first step, the coating gun is lowered to bring the discharge port into contact with the workpiece. In the second step, the coating gun is lifted to separate the workpiece from the discharge port. The coating method according to claim 1.

6. The workpiece is a sheet material for absorbent articles. The hot melt adhesive is blended with a material that changes color when it comes into contact with excrement. The coating method according to any one of claims 1 to 5.

7. A coating device for intermittently applying a hot melt adhesive from a coating gun to a workpiece conveyed in a certain direction, The coating gun having a discharge port for discharging the hot melt adhesive, the coating gun that brings the discharge port into contact with the workpiece in a coating state where the hot melt adhesive is applied to the workpiece, Separation means for separating the discharge port from the workpiece in the coating state, Comprising The coating state is a state where the hot melt adhesive is being discharged from the discharge port. The coating gun repeats the step of bringing the discharge port into contact with the workpiece and the step of separating the discharge port from the workpiece one or more times in the coating state, and then enters a non-coating state where the hot melt adhesive is not discharged from the discharge port, so that the hot melt adhesive is applied to the coated area of the workpiece and not applied to the non-coated area of the workpiece, thereby intermittently applying the hot melt adhesive. Coating device.

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