Coating method and coating device

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 device. [Background technology]

[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 a substrate such as a sheet material that is transported in a certain direction (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-131162 Summary of the Invention [Problem to be solved by the invention]

[0004] Hot melt adhesives are applied to a workpiece by heating and melting the solid raw material from an application gun. The hot melt adhesive is applied while the application gun's nozzle is in contact with the workpiece. Because hot melt adhesives have high viscosity even in a molten state, there is a risk that any hot melt adhesive that does not completely deposit on the sheet material will accumulate downstream of the application gun's nozzle in the conveying direction. When hot melt adhesive is applied intermittently, if hot melt adhesive accumulates downstream of the nozzle in the conveying direction, the application gun will drag the accumulated hot melt adhesive, resulting in hot melt adhesive being applied to areas that are not designed to receive hot melt adhesive.

[0005] An object of the present invention is to provide a technique that can prevent hot melt adhesive from being applied to areas that are not designed to be applied. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a step of moving the discharge port away from the object to be coated while the hot melt adhesive is being applied.

[0007] In detail, the present invention is a coating method for intermittently applying hot melt adhesive from a coating gun to a workpiece being transported in a fixed direction, wherein the coating gun has an outlet for discharging the hot melt adhesive, and includes a first step of bringing the outlet into contact with the workpiece in a coating state in which the hot melt adhesive is being applied to the workpiece, and a second step of moving the outlet away from the workpiece in the coating state.

[0008] In the above coating method, a roller is arranged below the workpiece and upstream of the discharge outlet, rotating in the conveying direction of the workpiece in synchronization with the conveying speed of the workpiece, and the roller has a circumferential portion and a flat portion, and in the first step, the workpiece is brought into contact with the discharge outlet by aligning the workpiece along the circumferential portion, and in the second step, the workpiece is separated from the discharge outlet by aligning the workpiece along the flat portion.

[0009] In the above coating method, a roller is disposed above the object to be coated and upstream of the discharge port, the roller rotating in the conveying direction of the object to be coated in synchronization with the conveying speed of the object to be coated. , the roller The radius of the circumferential portion is Object to be coated The distance may be longer than the distance to the workpiece, and in the first step, the roller and the workpiece are kept out of contact with each other to bring the discharge outlet into contact with the workpiece, and in the second step, the workpiece is pushed down by the circumferential portion to separate the workpiece from the discharge outlet.

[0010] In the coating method, a roller that rotates in a conveying direction of the workpiece in synchronization with the conveying speed of the workpiece is disposed below the workpiece so as to face the discharge port, the roller having a convex portion and a concave portion, Convex partmay face the discharge outlet, thereby bringing the discharge outlet into contact with the workpiece, and in the second step, the recess may face the discharge outlet, thereby separating the workpiece from the discharge outlet.

[0011] In the above coating method, a lifting device is provided to raise and lower the coating gun in the vertical direction, and in the first step, the coating gun is lowered to bring the discharge outlet into contact with the workpiece, and in the second step, the coating gun is raised to move the workpiece away from the discharge outlet.

[0012] The present invention also provides a coating method for intermittently applying hot melt adhesive from a coating gun to a workpiece being transported in a fixed direction, wherein the coating gun has a discharge outlet for discharging the hot melt adhesive, and the method may include a first step of bringing the discharge outlet into contact with the workpiece in a coating state in which the hot melt adhesive is being applied to the workpiece, and a second step of applying pressure to the workpiece from below in the coating state to filter out the hot melt adhesive that has accumulated downstream of the discharge outlet.

[0013] In the above coating method, a roller that can move up and down is arranged below the object to be coated and downstream of the discharge outlet, and that rotates in the transport direction of the object to be coated in synchronization with the transport speed of the object to be coated; in the first step, the roller contacts the object to be coated at a predetermined position; in the second step, the roller contacts the object to be coated above the predetermined position, thereby applying pressure to the object to be coated and filtering out the hot melt adhesive that has accumulated downstream of the discharge outlet; and the coating method may include a third step of lowering the roller in the coating state to separate the object from the discharge outlet.

[0014] In the above coating method, a roller is disposed below the workpiece and downstream of the discharge port, rotating in the conveying direction of the workpiece in synchronization with the conveying speed of the workpiece, and the roller has a circumferential portion corresponding to the length of the application range of the hot melt adhesive on the workpiece, an enlarged diameter portion whose diameter is larger than that of the circumferential portion, and which applies pressure to the workpiece and filters out the hot melt adhesive accumulated downstream of the discharge port, and a reduced diameter portion whose diameter is smaller than that of the circumferential portion, and which has a larger diameter than that of the enlarged diameter portion. and a reduced diameter section arranged so as to face the object to be coated later than the reduced diameter section, wherein in the first step, the object to be coated is brought into contact with the discharge port by aligning the object to be coated along the circumferential section, and in the second step, pressure is applied to the object to be coated by the expanded diameter section to filter out the hot melt adhesive that has accumulated downstream of the discharge port, and the coating method may include a third step of, in the coated state, directing the reduced diameter section toward the object to be coated, thereby separating the object from the discharge port.

[0015] In the above coating method, in the second step, the hot melt adhesive may be filtered out by blowing compressed air onto the article to be coated from below the article to be coated.

[0016] In the above coating method, the substrate may be a sheet material for an absorbent article, and the hot melt adhesive may contain a material that changes color when it comes into contact with excrement.

[0017] The present invention can also be seen from the perspective of an applicator. For example, the present invention may be an applicator that intermittently applies a hot melt adhesive from a coating gun to a workpiece that is transported in a fixed direction, the applicator gun having a discharge port that discharges the hot melt adhesive, the applicator gun bringing the discharge port into contact with the workpiece in a coating state in which the hot melt adhesive is applied to the workpiece, and a separating means for separating the discharge port from the workpiece in the coating state.

[0018] The present invention may also be an application device that intermittently applies hot melt adhesive from an application gun to a workpiece being transported in a fixed direction, the application gun having an outlet for discharging the hot melt adhesive, the application gun bringing the outlet into contact with the workpiece in an application state in which the hot melt adhesive is applied to the workpiece, and a filtering means that applies pressure to the workpiece from below in the application state to filter out the hot melt adhesive that has accumulated downstream of the outlet. [Effects of the Invention]

[0019] According to the present invention, it is possible to prevent the hot melt adhesive from being applied to areas that are not designed to be applied. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic diagram showing a coating method according to a comparative example. [Figure 2] FIG. 2 is a flowchart showing an outline of the coating method according to the first embodiment. [Figure 3] FIG. 3 is a schematic diagram showing a coating method according to Example 1 of Embodiment 1. As shown in FIG. [Figure 4] FIG. 4 is a schematic diagram showing a coating method according to Example 2 of Embodiment 1. As shown in FIG. [Figure 5] FIG. 5 is a schematic diagram showing a coating method according to Example 3 of Embodiment 1. As shown in FIG. [Figure 6] FIG. 6 is a schematic diagram showing a coating method according to Example 4 of Embodiment 1. As shown in FIG. [Figure 7] FIG. 7 is a schematic diagram showing a coating method according to Example 5 of Embodiment 1. As shown in FIG. [Figure 8] FIG. 8 is a schematic diagram showing a coating method according to Modification 1 of Example 5 of Embodiment 1. In FIG. [Figure 9] FIG. 9 is a schematic diagram showing a coating method according to Modification 2 of Example 5 of Embodiment 1. In FIG. [Figure 10] FIG. 10 is a schematic diagram showing a coating method according to Modification 3 of Example 5 of Embodiment 1. [Figure 11] FIG. 11 is a schematic diagram showing a coating method according to Example 6 of Embodiment 1. As shown in FIG. [Figure 12] FIG. 12 is a flowchart showing an outline of the coating method of the second embodiment. [Figure 13] FIG. 13 is a schematic diagram showing a coating method according to Example 1 of Embodiment 2. As shown in FIG. [Figure 14] FIG. 14 is a schematic diagram showing a coating method according to Example 2 of Embodiment 2. [Figure 15] FIG. 15 is a schematic diagram showing a coating method according to Example 3 of Embodiment 2. DETAILED DESCRIPTION OF THE INVENTION

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying 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 application method> The application method according to this embodiment is a method of intermittently applying a hot melt adhesive from an application gun to an article being transported in a fixed direction. Examples of the article being transported include sheet materials used for absorbent articles such as disposable diapers, urine pads, and sanitary napkins. In a production line for manufacturing absorbent articles, a hot melt adhesive is applied to a sheet material for the absorbent article being transported in a fixed direction. The hot melt adhesive may be applied intermittently to the sheet material so that it is applied to a designed application range (hereinafter referred to as "application range") and is not applied to a designed non-application range (hereinafter referred to as "non-application range"). The application range and non-application range are intermittently applied to the sheet material so that the hot melt adhesive is applied to a designed application range (hereinafter referred to as "application range") and is not applied to a designed non-application range. The application range is continuous in the conveyance direction of the sheet material, and when the application range of the sheet material passes under the application gun, the hot melt adhesive is discharged from the application gun, and when the non-application range of the sheet material passes under the application gun, the hot melt adhesive is not discharged from the application gun. In this way, the hot melt adhesive is intermittently applied to the sheet material being conveyed in a fixed direction.

[0023] Furthermore, in the application method according to this embodiment, the nozzle of the application gun is brought into contact with the sheet material when the hot melt adhesive is being applied to the sheet material. In contrast, when the hot melt adhesive is applied without the nozzle of the application gun being brought into contact with the sheet material, the hot melt adhesive is applied by spraying, which makes it difficult to achieve a clean, sharp application of the hot melt adhesive at the end when applying the hot melt adhesive intermittently. Therefore, when it is necessary to apply the hot melt adhesive intermittently (for example, when a non-adhesive region needs to be provided or when applying a hot melt adhesive containing a coloring substance to form an indicator), it is preferable to bring the application gun into contact with the sheet material, as in the application method according to this embodiment.

[0024] In the application method according to this embodiment, the hot melt adhesive is applied from the application gun to the sheet material in a melted state by heating the solid raw material to approximately 140° C. to 160° C. Because the hot melt adhesive has a high viscosity even in a melted state, there is a risk that the hot melt adhesive that does not completely adhere to the sheet material will accumulate downstream in the conveyance direction from the discharge port of the application 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 a sheet material S, which is a workpiece, as viewed from above, and the lower part of FIG. 1 is a schematic diagram of the sheet material S as viewed from the side. The sheet material S is transported in the direction indicated by arrow A1 in FIG. 1 by a roller R100, which rotates in the direction indicated by arrow A2 in FIG. 1. A raw material for hot melt adhesive H heated to approximately 140°C to 160°C is supplied to the coating gun G by a pump from a supply device (not shown), and the coating gun G is capable of discharging the hot melt adhesive H from a discharge port N provided at the tip. Furthermore, by switching the pump of the supply device between an operating state and an inoperable state, it is possible to switch between a discharge state in which the hot melt adhesive H is discharged from the discharge port N and a non-discharge state in which the hot melt adhesive H is not discharged from the discharge port N. Furthermore, in the comparative example, a contact-type coating gun G is used in which the discharge port N is constantly in contact with the sheet material.

[0026] In this comparative example, area B shown in Figure 1 is the designed application area for the hot melt adhesive H. When the rear end of application area B passes through the discharge port N, the hot melt adhesive H enters a non-discharged state. However, tailing occurs, in which the application gun G drags the hot melt adhesive H accumulated downstream of the discharge port N in the conveying direction, and the hot melt adhesive H is applied to the non-application area as well. As such, when the hot melt adhesive H is intermittently applied while the discharge port N of the application gun G is constantly in contact with the sheet material S, tailing occurs, in which the application gun G drags the hot melt adhesive H, and the hot melt adhesive H is applied to the non-application area as well. In absorbent articles, it is undesirable for adhesive properties to be exhibited in the non-application area where adhesive is desired to be non-adhesive. It is possible to reduce the viscosity of the hot melt adhesive H by raising the temperature of the hot melt adhesive H above 160°C, thereby suppressing tailing. However, raising the temperature of the hot melt adhesive H above 160°C is undesirable because it may change the performance of the hot melt adhesive H.

[0027] <Embodiment 1> First, the coating method according to the first embodiment 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 a coating state where the hot melt adhesive is applied to the sheet material. This prevents the hot melt adhesive from accumulating on the downstream side of the discharge port in the conveying direction. In the coating method according to this embodiment, the coating gun is separated from the sheet material in a non-coating state where the hot melt adhesive is applied to the sheet material. This prevents the hot melt adhesive from being dragged by the tool and prevents the hot melt adhesive from being applied to areas that are not designed to be applied.

[0028] FIG. 2 is a flowchart showing an outline of the coating method according to this embodiment. In this coating method, first, the discharge port is brought into contact with the sheet material in a coating state in which the hot melt adhesive H is applied to the sheet material (step S101, an example of the "first step" in this application). Next, the discharge port is separated from the sheet material in a coating state in which the hot melt adhesive H is applied (step S102, an example of the "second step" in this application). In this coating method, steps S101 and S102 are repeated one or more times to prevent the hot melt adhesive H from accumulating downstream of the discharge port in the conveyance direction. In this coating method, steps S101 and S102 are repeated one or more times, and then the hot melt adhesive H is put into a non-coating state, thereby intermittently coating the hot melt adhesive H on the sheet material being conveyed in a certain direction.

[0029] Next, the coating method according to this embodiment will be described in more detail with reference to FIGS. 3 to 8. Six specific examples, Examples 1 to 6, are illustrated in this embodiment. As shown in FIGS. 3 to 8, in this 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 approximately 140°C to 160°C, is supplied to the coating gun G by a pump from a supply device (not shown). Furthermore, as in the comparative example described above, the hot melt adhesive H can be switched between a discharging state and a non-discharging state by switching the pump of the supply device between an operating state and a non-operating state. Furthermore, in each of the examples shown in FIGS. 3 to 8, the sheet material is transported in the direction indicated by the arrow A1 in each figure.

[0030] Example 1 A coating method according to Example 1 will be described with reference to Figures 3(a) and (b). Figures 3(a) and (b) are schematic diagrams illustrating the coating method according to this example. The coating device used in the coating method according to this example includes a coating gun G and a roller R1 (an example of the "separating means" referred to in this application). The roller R1 rotates in the conveying direction (the direction indicated by the arrow A2) in synchronization with the conveying speed of the sheet material S. In the coating method according to this example, the roller R1, which is disposed below the sheet material S and upstream of the discharge port N, separates the discharge port N from the sheet material S.

[0031] FIG. 3(a) is a schematic diagram showing a state in which the discharge port N is in contact with the sheet material S in the hot melt adhesive H application state, and FIG. 3(b) is a schematic diagram showing a state in which the discharge port N is separated from the sheet material S in the hot melt adhesive H application state. The roller R1 has a circumferential portion C1 and a flat portion C2. In the application method according to this embodiment, the discharge port N is brought into contact with the sheet material S by aligning the sheet material along the circumferential portion C1 in the application state, and the sheet material S is separated from the discharge port N by aligning the sheet material S along the flat portion C2 in the application state. This allows the discharge port N to contact the sheet material S and the sheet material S to be separated from the discharge port N once or multiple times in the application state, preventing the hot melt adhesive H from accumulating downstream of the discharge port in the conveying direction.

[0032] <Example 2> A coating method according to Example 2 will be described with reference to Figures 4(a) and (b). Figures 4(a) and (b) are schematic diagrams illustrating the coating method according to this example. The coating device used in the coating method according to this example includes a coating gun G and a roller R2 (an example of the "separating means" referred to in this application). The roller R2 rotates in the conveying direction (the direction indicated by the arrow A2) in synchronization with the conveying speed of the sheet material S. In the coating method according to this example, the roller R2, which is disposed above the sheet material S and upstream of the discharge port N, separates the discharge port N from the sheet material S.

[0033] FIG. 4(a) shows the state in which the discharge port N contacts the sheet material S while the hot melt adhesive H is being applied. 4(a) and 4(b) are schematic diagrams showing a state in which the discharge port N is separated from the sheet material S in the hot melt adhesive H coating state, respectively. 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 this embodiment, the roller R2 and the sheet material S are kept out of contact with each other to bring the discharge port N into contact with the sheet material S, and in the coating state, the sheet material S is pressed down by the circumferential portion C3 to separate the sheet material S from the discharge port N. As a result, in the coating state, the discharge port N can be brought into contact with the sheet material S and the sheet material S can be separated from the discharge port N once or multiple times, which prevents the hot melt adhesive H from accumulating downstream of the discharge port in the conveyance direction.

[0034] Example 3 A coating method according to Example 3 will be described with reference to Figures 5(a) and (b). Figures 5(a) and (b) are schematic diagrams illustrating the coating method according to this example. The coating device used in the coating method according to this example includes a coating gun G and a roller R3 (an example of the "separating means" referred to in this application). The roller R3 rotates in the conveying direction (the direction indicated by the arrow A2) in synchronization with the conveying 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 R3, which is arranged below the sheet material S so as to face the discharge port N.

[0035] FIG. 5(a) is a schematic diagram showing a state in which the discharge port N is in contact with the sheet material S in the state in which the hot melt adhesive H is being applied, and FIG. 5(b) is a schematic diagram showing a state in which the discharge port N is separated from the sheet material S in the state in which the hot melt adhesive H is being applied. The roller R3 has a convex portion D1 and a concave portion D2. In the application method according to this embodiment, in the application state, Convex partD1 faces the discharge outlet N, bringing the discharge outlet N into contact with the sheet material S, and in the application state, recess D2 faces the discharge outlet N, separating the sheet material S from the discharge outlet N. This allows the discharge outlet N to come into contact with the sheet material S and the sheet material S to be separated from the discharge outlet N once or multiple times in the application state, preventing the hot melt adhesive H from accumulating downstream of the discharge outlet in the conveying direction.

[0036] Example 4 A coating method according to Example 4 will be described with reference to Figures 6(a) and (b). Figures 6(a) and (b) are schematic diagrams illustrating the coating method according to this example. The coating device used in the coating method according to this example includes a coating gun G and a roller R4 (an example of the "separating means" referred to in this application). The roller R4 rotates in the conveying direction (the direction indicated by the arrow A2) in synchronization with the conveying 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, which is disposed below the sheet material S and upstream 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 composed of a first roller R41 and a second roller R42. The first roller R41 and the second roller R42 form a circumferential portion C4 of the roller R4. A separation portion D3 where the circumferential portion C4 is not formed is provided between the first roller R41 and the second roller R42. In the coating method according to this embodiment, the discharge port N is brought into contact with the sheet material S by aligning the sheet material along the circumferential portion C4 in the coating state, and the sheet material S is separated from the discharge port N by aligning the sheet material S along the separation portion D3 in the coating state. This allows the discharge port N to contact the sheet material S and the sheet material S to be separated from the discharge port N once or multiple times during application, thereby preventing the hot melt adhesive H from accumulating downstream of the discharge port in the conveying direction.

[0038] <Example 5> A coating method according to Example 5 will be described with reference to FIGS. 7(a) and 7(b). FIGS. 7(a) and 7(b) are schematic diagrams illustrating the coating method according to this example. The coating device used in the coating method according to this example includes a coating gun G and a lifting device M1 (an example of the "separating means" referred to in this application) that raises and lowers the coating gun G in the vertical direction. The lifting device M1 has two guide rails L arranged opposite a drive unit M11, and the drive unit M11 can drive the coating gun G up and down along the guide rails L. The drive unit M11 may be configured to include, for example, a motor or a hydraulic device. In the coating method according to this example, the coating gun G is raised by the lifting device M1 to separate the discharge port N from the sheet material S.

[0039] 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 state in which the hot melt adhesive H is being applied, 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 state in which the hot melt adhesive H is being applied. In the application method according to this embodiment, the application gun G is lowered in the application state to bring the discharge port N into contact with the sheet material S, and the application gun G is raised in the application state to separate the sheet material S from the discharge port N. This allows the discharge port N to be brought into contact with the sheet material S and the sheet material S to be separated from the discharge port N once or multiple times in the application state, preventing the hot melt adhesive H from accumulating downstream of the discharge port in the conveyance direction.

[0040] <Modification 1 of Example 5> A coating method according to Modification 1 of Example 5 will be described with reference to FIGS. 8(a) and 8(b). FIGS. 8(a) and 8(b) are schematic diagrams illustrating the coating method according to this modification. The coating device used in the coating method according to this modification includes a coating gun G and a lifting device M20 (an example of the "separating means" referred to herein) that lifts and lowers the coating gun G in the vertical direction. The lifting device M20 is a power cylinder and includes a cylinder tube M21, a piston rod M22 that is movable forward and backward relative to the cylinder tube M21, and two guide rails L that are arranged opposite each other and extend in the vertical direction. The lower end of the piston rod M22 is connected to the coating gun G. A piping (not shown) is connected to the cylinder tube M21, and gas, oil, or other liquids serving as a power source are supplied and discharged through the piping, thereby enabling the piston rod M22 to move forward and backward relative to the cylinder tube M21. The lifting device M20 can drive the coating gun G up and down along the guide rails L by moving the piston rod M22 forward and backward relative 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 using the lifting device M20.

[0041] 8(a) is a schematic diagram showing the state in which the hot melt adhesive H is applied, and FIG. 8(b) is a schematic diagram showing the state in which the hot melt adhesive H is not applied. In the application method according to this modified example, in the applied state, the application gun G is lowered to bring the discharge port N into contact with the sheet material S, and in the non-applied state, the application gun G is raised to separate the sheet material S from the discharge port N. This allows the sheet material S to be separated from the discharge port N when switching the hot melt adhesive H from the applied state to the non-applied state.

[0042] <Modification 2 of Example 5> A coating method according to Modified Example 2 of Example 5 will be described with reference to Figures 9(a) and (b). Figures 9(a) and (b) are schematic diagrams illustrating the coating method according to this modified example. The coating device used in the coating method according to this modified example includes a coating gun G and a lifting device M30 (an example of the "separating means" referred to in this application) that lifts and lowers the coating gun G. The lifting device M30 is a power cylinder, and includes a cylinder tube M31, a piston rod M32 that is provided so as to be able to advance and retreat relative 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 relative to the piston rod M32. Furthermore, the lower end of the arm M33 is connected to the coating gun G. The coating gun G is rotatable around the rotation axis AX2. The cylinder tube M A pipe (not shown) is connected to the cylinder tube M31, and gas or liquid such as oil, which serves as a power source, is supplied and discharged through the pipe, thereby allowing the piston rod M32 to move back and forth relative to the cylinder tube M31. The lifting device M30 moves the piston rod M32 back and forth relative to the cylinder tube M31, thereby rotating the arm M33 and the coating gun G connected thereto, and can switch between a state in which the discharge port N of the coating gun G contacts the sheet material S and a state in which the discharge port N of the coating gun G is separated from the sheet material S.

[0043] 9(a) is a schematic diagram showing the state in which the hot melt adhesive H is applied, and FIG. 9(b) is a schematic diagram showing the state in which the hot melt adhesive H is not applied. In the application method according to this modified example, in the non-application state, the application gun G is rotated downstream to separate the sheet material S from the discharge port N. This allows the sheet material S to be separated from the discharge port N when switching the hot melt adhesive H from the application state to the non-application state.

[0044] <Modification 3 of Example 5> A coating method according to Modification 3 of Example 5 will be described with reference to FIGS. 10(a) and 10(b). FIGS. 10(a) and 10(b) are schematic diagrams illustrating the coating method according to this modification. The coating device used in the coating method according to this modification includes a coating gun G and a lifting device M40 (an example of the "separating means" referred to in the present application) that lifts and lowers the coating gun G in the vertical direction. The lifting device M40 has a motor M41, a pinion gear M42 fixed to the rotation shaft of the motor M41, 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 drives the motor M41 to rotate the pinion gear M42, thereby lifting and lowering the rack gear M43 in the vertical direction. This allows the lifting device M40 to drive the coating gun G up and down. In the coating method according to this modification, the discharge port N is separated from the sheet material S by lifting the coating gun G using the lifting device M40.

[0045] 10(a) is a schematic diagram showing the state in which the hot melt adhesive H is applied, and FIG. 10(b) is a schematic diagram showing the state in which the hot melt adhesive H is not applied. In the application method according to this modified example, in the applied state, the application gun G is lowered to bring the discharge port N into contact with the sheet material S, and in the non-applied state, the application gun G is raised to separate the sheet material S from the discharge port N. This allows the sheet material S to be separated from the discharge port N when switching the hot melt adhesive H from the applied state to the non-applied state.

[0046] Example 6 A coating method according to Example 6 will be described with reference to Figures 11(a) and (b). Figures 11(a) and (b) are schematic diagrams illustrating the coating method according to this example. The coating device used in the coating method according to this example includes a coating gun G and a suction device M2 (an example of the "separating means" in this application) that lowers the sheet material S by sucking it. The suction device M2 is disposed below the sheet material S in a position opposite the discharge port N. 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] 11(a) is a schematic diagram showing a state in which the discharge port N is in contact with the sheet material S in the state in which the hot melt adhesive H is being applied, and FIG. 11(b) is a schematic diagram showing a state in which the discharge port N is separated from the sheet material S in the state in which the hot melt adhesive H is being applied. In the application method according to this embodiment, the discharge port N is brought into contact with the sheet material S in the application state, and the sheet material S is separated from the discharge port N by sucking the sheet material S with a suction device M in the application state. This allows the discharge port N to be brought into contact with the sheet material S and the sheet material S to be separated from the discharge port N once or multiple times in the application state, thereby preventing the hot melt adhesive H from accumulating downstream of the discharge port in the conveyance direction.

[0048] The coating method according to this embodiment can employ any of the above-described examples. According to the coating method according to each example of this embodiment, it is possible to prevent the hot melt adhesive H from accumulating downstream of the discharge port in the conveyance direction and to prevent the application gun G from dragging the hot melt adhesive H, thereby preventing the hot melt adhesive H from being applied to areas not intended for application.

[0049] <Embodiment 2> Next, a coating method according to embodiment 2 will be described. In the coating method according to this embodiment, when the hot melt adhesive H is being applied, the hot melt adhesive H that has accumulated downstream of the discharge port is filtered out. This prevents the hot melt adhesive H from accumulating downstream of the discharge port in the conveying direction. The coating method according to this embodiment prevents the application gun from dragging the hot melt adhesive H when the hot melt adhesive H is not being applied, and can prevent the hot melt adhesive H from being applied to areas that are not designed to be applied.

[0050] FIG. 12 is a flowchart outlining the coating method according to this embodiment. In the coating method according to this embodiment, first, hot melt adhesive H is coated onto a sheet material (step S201, an example of the "first step" in this application). Next, while the hot melt adhesive H is being coated, pressure is applied to the sheet material from below to filter out the hot melt adhesive H that has accumulated downstream of the discharge port (step S202, an example of the "second step" in this application). Next, while the hot melt adhesive H is being coated, the sheet material is separated from the discharge port (step S203, an example of the "third step" in this application). In the coating method according to this embodiment, steps S201 to S203 are repeated one or more times to prevent the hot melt adhesive H from accumulating downstream of the discharge port in the conveying direction. In the application method according to the present embodiment, after steps S201 to S203 are repeated one or more times, the hot melt adhesive H is put into a non-application state, so that the hot melt adhesive H can be intermittently applied to the sheet material being transported in a fixed direction. Note that step S203 can be omitted.

[0051] Next, the coating method according to this embodiment will be described in more detail with reference to Figs. 13 to 15. In this embodiment, three specific examples, Examples 1 to 3, are illustrated. As shown in Figs. 13 to 15, in this embodiment, similar to the above-described Example 1, the coating gun G has a discharge port N that discharges the hot melt adhesive H. Furthermore, in this embodiment, a contact-type coating gun G is used, in which the discharge port N is brought into contact with the sheet material S in a discharged state. Furthermore, in each of the examples shown in Figs. 10 to 12, the sheet material is transported in the direction indicated by the arrow A1 in each figure.

[0052] Example 1 The coating method according to Example 1 will be described with reference to Figures 13(a) to (c). Figures 13(a) to (c) are schematic diagrams illustrating the coating method according to this example. The upper parts of Figures 13(a) to (c) are schematic diagrams of the sheet material S viewed from above, and the lower parts of Figures 13(a) to (c) are schematic diagrams of the sheet material S viewed from the side. The coating device 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 this application). The roller R10 is located below the sheet material S, with its center of rotation O located downstream of the discharge port N, and is movable up and down. The roller R10 rotates in the conveying direction of the sheet material S (the direction indicated by arrow A2) in synchronization with the conveying speed of the sheet material S.

[0053] 13(a) shows the process of applying hot melt adhesive H. In this process, roller R10 is in contact with sheet material S at a predetermined position, and discharge port N is in contact with sheet material S. Sheet material S is transported downstream in the tangential direction of the circumference of roller R10 while in contact with discharge port N. Note that the predetermined position of roller R10 in this process is a height at which sheet material S is in an appropriate position relative to discharge port N when hot melt adhesive H is applied.

[0054] 13(b) shows the process of filtering out the hot melt adhesive H. In this process, the roller R10 applies pressure to the sheet material S by contacting the sheet material S above a predetermined position, filtering out the hot melt adhesive H that has accumulated downstream of the discharge port N. This makes it possible to filter out the hot melt adhesive H that has accumulated downstream of the discharge port N while the hot melt adhesive H is being applied. This prevents the hot melt adhesive H from accumulating downstream of the discharge port in the conveyance direction, and prevents the hot melt adhesive H from being applied to areas that are not designed to be applied.

[0055] 13(c) shows the process of separating the sheet material S from the discharge port N after the hot melt adhesive H has been filtered out and in a state where the hot melt adhesive H is not being applied. In this process, the roller R10 is lowered to separate the sheet material S from the discharge port N. This process prevents the hot melt adhesive H from accumulating downstream in the conveying direction of the discharge port, even if the hot melt adhesive H was not completely filtered out in the previous process, and prevents the hot melt adhesive H from being applied to a non-application area in the design.

[0056] <Example 2> A coating method according to Example 2 will be described with reference to Figures 14(a) to (c). Figures 14(a) to (c) are schematic diagrams illustrating the coating method according to this example. The upper parts of Figures 14(a) to (c) are schematic diagrams of the sheet material S viewed from above, and the lower parts of Figures 14(a) to (c) are schematic diagrams of the sheet material S viewed from the side. The coating device 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 this application). The roller R20 is located below the sheet material S, and its center of rotation O is located downstream of the discharge port N. The roller R20 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.

[0057] The roller R20 has a circumferential portion R21, an expanded diameter portion R22 that is larger in diameter than the circumferential portion R21, and a reduced diameter portion R23 that is smaller in diameter than the circumferential portion R21. The expanded diameter portion R22 applies pressure to the sheet material S by coming into contact with the sheet material S, filtering out the hot melt adhesive H that has accumulated downstream of the discharge port N. The distance between the outer periphery of the expanded diameter portion R22 and the center of rotation of the roller R20 is set to a length that applies sufficient pressure to the sheet material S. The reduced diameter portion R23 is positioned behind the expanded diameter portion R22 so as to face the sheet material S. The distance between the outer periphery of the reduced diameter portion R23 and the center of rotation of the roller R20 is set to a length that allows the sheet material S to be separated from the nozzle N when the reduced diameter portion R23 faces the sheet material S.

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

[0059] Figure 14(b) shows the process of filtering out the hot melt adhesive H. In this process, the expanded diameter portion R22 is in contact with the sheet material S, and by applying pressure to the sheet material S with the expanded diameter portion R22, it is possible to filter out the hot melt adhesive H that has accumulated downstream of the discharge port N. This makes it possible to filter out the hot melt adhesive H that has accumulated downstream of the discharge port N while the hot melt adhesive H is being applied. This prevents the hot melt adhesive H from accumulating downstream of the discharge port in the conveyance direction, and prevents the hot melt adhesive H from being applied to areas that are not designed to be applied.

[0060] FIG. 14(c) shows a process of separating the sheet material S from the discharge port N in a state where the hot melt adhesive H is not applied after filtering out the hot melt adhesive H. In this process, the sheet material S is separated from the discharge port N by directing the reduced diameter portion R23 toward the sheet material S. This process prevents the application gun G from dragging the hot melt adhesive H even if the hot melt adhesive H was not completely filtered out in the previous process, and prevents the hot melt adhesive H from being applied to areas that are not designed to be applied.

[0061] Example 3 A coating method according to Example 3 will be described with reference to Figures 15(a) and (b). Figures 15(a) and (b) are schematic diagrams illustrating the coating method according to this example. The upper parts of Figures 15(a) and (b) are schematic diagrams of the sheet material S viewed from above, and the lower parts of Figures 15(a) and (b) are schematic diagrams of the sheet material S viewed from the side. The coating device used in the coating method according to this example includes a coating gun G and an air blower M3 (an example of the "filtering means" referred to in this application). The air blower M3 is disposed below the sheet material S and blows compressed air toward the downstream side of the discharge port N.

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

[0063] 15(b) shows the process of filtering out the hot melt adhesive H. In this process, compressed air is blown onto the sheet material S from the underside of the sheet material S by the air blower M3, thereby filtering out the hot melt adhesive H that has accumulated downstream of the discharge port N. This allows the hot melt adhesive H that has accumulated downstream of the discharge port N to be filtered out when switching the hot melt adhesive H from the application state to the non-application state. This prevents the application gun G from dragging the hot melt adhesive H in the non-application state, and prevents the hot melt adhesive H from being applied to areas that are not designed to be applied.

[0064] The coating method according to this embodiment can employ any of the above-described examples. According to the coating method according to each example of this embodiment, it is possible to prevent the hot melt adhesive H from accumulating downstream of the discharge port in the conveyance direction and to prevent the application gun G from dragging the hot melt adhesive H, thereby preventing the hot melt adhesive H from being applied to areas not intended for application.

[0065] In the above embodiment, the hot melt adhesive H may be blended with an indicator material that changes color upon contact with excrement. In the absorbent article, the portion to which the indicator material is applied functions as an indicator that indicates to the outside the presence or absence of excrement, such as urination. The indicator is provided, for example, by applying the hot melt adhesive H blended with the indicator material to the skin-facing side of the backsheet. The indicator material may be a moisture-detecting material, a pH-reactive material, or the like. According to the application method of this embodiment, the hot melt adhesive H blended with this material can be applied to the indicator placement area, and the hot melt adhesive H can be prevented from being applied to the non-indicator placement area, allowing the indicator to be positioned within the designed range. This allows the indicator to be positioned within the designed range of the absorbent article, preventing the indicator from interfering with the design of the absorbent article.

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

[0067] A1, A2... arrows C1, C3, C4: Circumferential section C2 · Flat part G··Dispenser Gun H··Hot melt adhesive M1, M20, M30, 40... Lifting device M2·Suction device M3...Blower device N··Discharge port R1, R2, R3, R4, R10, R20, R100 rollers S··Sheet material

Claims

1. A coating method for intermittently coating a hot melt adhesive from a coating gun onto a substrate being transported in a fixed direction, comprising: the application gun has a discharge port for discharging the hot melt adhesive, A first step of contacting the discharge port with the workpiece in a coating state in which the hot melt adhesive is applied to the workpiece; a second step of filtering out the hot melt adhesive accumulated downstream of the discharge port by applying pressure to the object to be coated from below in the coating state; Including, The application state is a state in which 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 is established in which the hot melt adhesive is not discharged from the discharge port, thereby applying the hot melt adhesive to the coating area of ​​the workpiece, and intermittently applying the hot melt adhesive while not applying the hot melt adhesive to the non-coating area of ​​the workpiece, In the second step, pressure is applied to the object to be coated so that the object comes into stronger contact with the discharge outlet than in the first step, and the hot melt adhesive accumulated downstream of the discharge outlet is filtered out. Application method.

2. a roller that is movable up and down and rotates in the conveying direction of the workpiece in synchronization with the conveying speed of the workpiece is disposed below the workpiece and downstream of the discharge port; In the first step, the roller is in contact with the object to be coated at a predetermined position, In the second step, the roller contacts the object to be coated above the predetermined position, thereby applying pressure to the object to be coated and filtering out the hot melt adhesive that has accumulated downstream of the discharge port; The coating method includes a third step of lowering the roller in the coating state to separate the workpiece from the discharge port. The coating method according to claim 1 .

3. a roller is disposed below the workpiece and downstream of the discharge port, the roller rotating in the conveying direction of the workpiece in synchronization with the conveying speed of the workpiece; The roller is a circumferential portion corresponding to the length of the application range of the hot melt adhesive on the object to be coated; an enlarged diameter portion having a diameter larger than that of the circumferential portion, which applies pressure to the object to be coated and filters out the hot melt adhesive accumulated downstream of the discharge port; A reduced diameter portion having a diameter smaller than that of the circumferential portion, the reduced diameter portion being arranged rearward of the expanded diameter portion so as to face the object to be coated; and In the first step, the object to be coated is brought into contact with the discharge port by aligning the object to be coated along the circumferential portion, In the second step, the hot melt adhesive accumulated downstream of the discharge port is filtered out by applying pressure to the object to be coated using the expanded diameter portion, The coating method includes a third step of directing the reduced diameter portion toward the workpiece in the coating state to separate the workpiece from the discharge port. The coating method according to claim 1 .

4. In the second step, compressed air is applied to the object to be coated from below to filter out the hot melt adhesive. The coating method according to claim 1 .

5. The substrate is a sheet material for an absorbent article, The hot melt adhesive contains a material that changes color when it comes into contact with excrement. The coating method according to any one of claims 1 to 4.

6. An application device that intermittently applies hot melt adhesive from an application gun to an object to be coated that is transported in a certain direction, The application gun has a discharge port for discharging the hot melt adhesive, and the discharge port is brought into contact with the workpiece in a coating state in which the hot melt adhesive is applied to the workpiece; a filtering means for filtering out the hot melt adhesive accumulated downstream of the discharge port by applying pressure to the object to be coated from below in the coating state; Equipped with The application state is a state in which the hot melt adhesive is being discharged from the discharge port, a step of bringing the discharge port into contact with the object to be coated in the coating state and a step of applying pressure to the object to be coated by the object to be coated by strongly contacting the discharge port in the coating state are repeated once or a plurality of times, and then a non-coating state is established in which the hot melt adhesive is not discharged from the discharge port, thereby coating the hot melt adhesive in the coating area of ​​the object to be coated and intermittently coating the hot melt adhesive without coating the hot melt adhesive in the non-coating area of ​​the object to be coated; The filtering means applies pressure to the object to be coated so that the object to be coated comes into stronger contact with the discharge port than in the step of contacting the discharge port with the object to be coated, and filters out the hot melt adhesive that has accumulated downstream of the discharge port. Coating equipment.

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