Application method and application 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 apparatus. [Background technology]

[0002] In the manufacturing process of absorbent articles such as disposable diapers, incontinence 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] JP 2011-131162 A Summary of the Invention [Problem to be solved by the invention]

[0004] Hot melt adhesive is applied to the workpiece from a coating gun in a state where the solid raw material is heated and melted. The hot melt adhesive is applied with the nozzle of the coating gun in contact with the workpiece. Since the hot melt adhesive has a high viscosity even in a molten state, there is a risk that the hot melt adhesive that does not completely fit on the sheet material will accumulate downstream of the nozzle of the coating gun 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 coating gun will drag the accumulated hot melt adhesive, causing tailing, and hot melt adhesive will be applied to non-coating areas that are not designed to be coated with hot melt adhesive.

[0005] An object of the present invention is to provide a technique capable of preventing a 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 separating the discharge port from the workpiece while the hot melt adhesive is being applied.

[0007] In detail, the present invention relates to a coating method for intermittently applying hot melt adhesive from a coating gun to a workpiece transported in a fixed direction, the coating gun having an outlet for discharging the hot melt adhesive, and including a first step of bringing the outlet into contact with the workpiece in a coating state in which the hot melt adhesive is 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, which rotates in the transport direction of the workpiece in synchronization with the transport 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 workpiece and upstream of the discharge port, the roller rotating in a conveying direction of the workpiece in synchronization with a conveying speed of the workpiece, the roller has a circumferential portion corresponding to a length of a non-applied area of ​​the workpiece of the hot melt adhesive, and a radius of the circumferential portion is 10 mm from a center of rotation of the roller to the sheet material. In the first step, the roller and the workpiece are kept out of contact with each other to bring the discharge port 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 port.

[0010] In the above coating method, a roller that rotates in the transport direction of the workpiece in synchronization with the transport speed of the workpiece is arranged below the workpiece so as to face the discharge outlet, and the roller has a convex portion and a concave portion, and in the first step, the protruding portion faces the discharge outlet, bringing the discharge outlet into contact with the workpiece, and in the second step, the concave portion faces the discharge outlet, 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 a 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 constant direction, the coating gun having an outlet for discharging the hot melt adhesive, and including a first step of bringing the outlet into contact with the workpiece in a coating state in which the hot melt adhesive is applied to the workpiece, and a second step of applying pressure from below to the workpiece in the coating state to filter out the hot melt adhesive that has accumulated downstream of the outlet.

[0013] In the above coating method, a roller that is vertically movable is arranged below the workpiece and downstream of the discharge port, and rotates in the transport direction of the workpiece in synchronization with the transport speed of the workpiece, and in the first step, the roller contacts the workpiece at a predetermined position, and in the second step, the roller contacts the workpiece above the predetermined position to apply pressure to the workpiece and filter out the hot melt adhesive that has accumulated downstream of the discharge port, and the coating method may include a third step of lowering the roller in the coating state to separate the workpiece from the discharge port.

[0014] In the above coating method, a roller is disposed below the workpiece and downstream of the discharge port, the roller rotating in a conveying direction of the workpiece in synchronization with the conveying speed of the workpiece, the roller having a circumferential portion corresponding to the length of an application range of the hot melt adhesive on the workpiece, an enlarged diameter portion having a diameter larger than that of the circumferential portion, the enlarged diameter portion applying pressure to the workpiece and filtering out the hot melt adhesive accumulated downstream of the discharge port, and a reduced diameter portion having a diameter smaller than that of the circumferential portion, the enlarged diameter portion applying pressure to the workpiece and filtering out the hot melt adhesive accumulated downstream of the discharge port. and a reduced diameter portion arranged so as to face the object to be coated laterally, 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 portion, and in the second step, pressure is applied to the object to be coated by the expanded diameter portion 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 portion toward the object to separate the object from the discharge port.

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

[0016] In the above coating method, the substrate may be a sheet material for absorbent articles, 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 understood from the aspect of an application device. For example, the present invention may be an application device that intermittently applies a hot melt adhesive from a application gun to a workpiece transported in a fixed direction, the application gun having a discharge port for discharging the hot melt adhesive, the application 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 provide a coating device that intermittently applies hot melt adhesive from a coating gun to a workpiece transported in a constant direction, the coating gun having an outlet for discharging the hot melt adhesive, the coating gun bringing the outlet into contact with the workpiece in a coating state in which the hot melt adhesive is applied to the workpiece, and a filtering means that filters out the hot melt adhesive that has accumulated downstream of the outlet by applying pressure to the workpiece from below in the coating state. Effect 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 for application. [Brief description of the drawings]

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

[0021] Hereinafter, embodiments of the present invention will be described 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 application method according to this embodiment is a method in which a hot melt adhesive is intermittently applied from an application gun to a workpiece transported in a fixed direction. Examples of workpieces include sheet materials used for absorbent articles such as disposable diapers, urine pads, and sanitary products. In a production line for manufacturing absorbent articles, a hot melt adhesive is applied to a sheet material for absorbent articles that is transported in a fixed direction. The hot melt adhesive may be applied intermittently to the sheet material so that the adhesive is applied to a designed application range (hereinafter referred to as the "application range") and not to a designed non-application range (hereinafter referred to as the "non-application range"). The application range and non-application ranges are determined by the following formula: The application range is continuous in the conveying 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 conveyed in a fixed direction.

[0023] In addition, in the application method according to the present embodiment, the nozzle of the application gun is brought into contact with the sheet material in the application state in which the hot melt adhesive is applied to the sheet material. In contrast, when the hot melt adhesive is applied without bringing the nozzle of the application 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 smoothly at the end portion. Therefore, when it is necessary to apply the hot melt adhesive intermittently (when it is necessary to provide a non-adhesive region, 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 the present embodiment.

[0024] In the application method according to the present 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. Since 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 fit on the sheet material will accumulate downstream in the conveying 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 coated object, 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 the arrow A1 in FIG. 1 by a roller R100 rotating in the direction indicated by the arrow A2 in FIG. 1. The coating gun G is supplied with raw materials of hot melt adhesive H heated to about 140°C to 160°C by a pump from a supply device (not shown), and the coating gun G can discharge the hot melt adhesive H from a discharge port N provided at the tip. In addition, 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 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. In addition, in the comparative example, a contact type coating gun G in which the discharge port N is constantly in contact with the sheet material is adopted.

[0026] In this comparative example, the range B shown in FIG. 1 is the design 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-discharged state. However, tailing occurs in which the application gun G drags the hot melt adhesive H accumulated on the downstream side of the discharge port N in the conveying direction, and the hot melt adhesive H is applied to the non-applied range as well. In this way, when the hot melt adhesive H is intermittently applied with the discharge port N of the application gun G always 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-applied range as well. In an absorbent article, it is not preferable for the adhesiveness to be exerted in the non-applied range that is desired to be non-adhesive. It is possible to suppress the occurrence of tailing by lowering the viscosity of the hot melt adhesive H by raising the temperature of the hot melt adhesive H above 160°C, but if the hot melt adhesive H is raised 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 the first embodiment will be described. In the coating method according to the present embodiment, the discharge port of the coating gun is separated from the sheet material in a coating state in which 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 the present embodiment, the coating gun is separated from the sheet material in a non-coating state of the hot melt adhesive. This prevents the hot melt adhesive from being dragged by the tool and prevents hot melt adhesive from being applied to areas not intended for application.

[0028] FIG. 2 is a flow chart 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 in which 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" in the present application). Next, in a coating state in which the hot melt adhesive H is applied, the discharge port is separated from the sheet material (step S102, an example of the "second step" in the present application). In the coating method according to the present embodiment, steps S101 and S102 are repeatedly performed once or multiple times to prevent the hot melt adhesive H from accumulating on the downstream side of the discharge port in the conveying direction. In the coating method according to the present embodiment, after steps S101 and S102 are repeated once or multiple times, the hot melt adhesive H is put into a non-coated state, so that the hot melt adhesive H can be intermittently applied to the sheet material being conveyed in a certain direction.

[0029] Next, the coating method according to the present embodiment will be described in more detail with reference to Figs. 3 to 8. In the present embodiment, six specific examples, 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 coating gun G is supplied with raw materials of the hot melt adhesive H heated to about 140°C to 160°C by a pump from a supply device (not shown). Also, as in the above-mentioned comparative example, the hot melt adhesive H can be switched between a discharge state and a non-discharge state by switching the pump of the supply device between an operating state and a non-operating state. Also, 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 Figs. 3(a) and (b). Figs. 3(a) and (b) are schematic diagrams for explaining 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" 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 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 separated 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 embodiment, the discharge port N is brought into contact with the sheet material S by placing the sheet material along the circumferential portion C1 in the coating state, and the sheet material S is separated from the discharge port N by placing the sheet material S along the flat portion C2 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 in the coating state, and prevents the hot melt adhesive H from accumulating on the downstream side of the discharge port in the conveying direction.

[0032] <Example 2> A coating method according to Example 2 will be described with reference to Figs. 4(a) and (b). Figs. 4(a) and (b) are schematic diagrams for explaining 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" 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 a state in which the discharge port N is in contact with the sheet material S while the hot melt adhesive H is being applied. 4(a) and 4(b) are schematic diagrams showing a state where the discharge port N is separated from the sheet material S in a coating state of 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 this embodiment, the roller R2 and the sheet material S are not in 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 pushed down by the circumferential portion C3 to separate the sheet material S from the discharge port N. In this way, 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, and the hot melt adhesive H can be prevented from accumulating on the downstream side of the discharge port in the conveying direction.

[0034] <Example 3> A coating method according to Example 3 will be described with reference to Figs. 5(a) and (b). Figs. 5(a) and (b) are schematic diagrams for explaining 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" 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 arranged so as to face the discharge port N on the lower side of the sheet material S.

[0035] FIG. 5(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. 5(b) is a schematic diagram showing a state where the discharge port N is separated from the sheet material S in the coating state of the hot melt adhesive H. The roller R3 has a convex portion D1 and a concave portion D2. In the coating method according to this embodiment, the protrusion portion D1 faces the discharge port N to bring the discharge port N into contact with the sheet material S in the coating state, and the concave portion D2 faces the discharge port N to separate the sheet material S from the discharge port N in the coating state. This allows the discharge port N to come 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 coating state, and prevents the hot melt adhesive H from accumulating on the downstream side of the discharge port in the conveying direction.

[0036] <Example 4> A coating method according to Example 4 will be described with reference to Figs. 6(a) and (b). Figs. 6(a) and (b) are schematic diagrams for explaining 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" 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 disposed below the sheet material S and upstream of the discharge port N.

[0037] FIG. 6(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. 6(b) is a schematic diagram showing a state where 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 a circumferential portion C4 of the roller R4. In addition, 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 embodiment, the discharge port N is brought into contact with the sheet material S by making the sheet material follow the circumferential portion C4 in the coating state, and the sheet material S is separated from the discharge port N by making the sheet material S follow the separation portion D3 in the coating state. This allows, in the coating state, the discharge port N to be brought into contact with the sheet material S and the sheet material S to be moved away from the discharge port N once or multiple times, thereby preventing the hot melt adhesive H from accumulating on the downstream side 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 (b). Figs. 7(a) and (b) are schematic diagrams for explaining 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" in this application) for lifting the coating gun G in the vertical direction. The lifting device M1 has two guide rails L arranged opposite to a drive unit M11, and the coating gun G can be driven up and down along the guide rails L by the drive unit M11. 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 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. 7(b) is a schematic diagram showing a state where 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 embodiment, the coating gun G is lowered in the coating state to bring the discharge port N into contact with the sheet material S, and the coating gun G is raised in the coating state to separate the sheet material S from the discharge port N. In this way, 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, and the hot melt adhesive H can be prevented from accumulating on the downstream side of the discharge port in the conveying 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 (b). Figs. 8(a) and (b) are schematic diagrams for explaining 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" in the present application) for lifting 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 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 a liquid such as gas or oil as a power source is supplied and discharged through the pipe, so that 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 moving the piston rod M22 forward and backward 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 using the lifting device M20.

[0041] Fig. 8(a) is a schematic diagram showing a coated state of hot melt adhesive H, and Fig. 8(b) is a schematic diagram showing a non-coated state of hot melt adhesive H. In the coating method according to this modified example, in the coated state, the coating gun G is lowered to bring the discharge port N into contact with the sheet material S, and in the non-coated state, the coating 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 the hot melt adhesive H is switched from the coated state to the non-coated state.

[0042] <Modification 2 of Example 5> A coating method according to Modification 2 of Example 5 will be described with reference to Figs. 9(a) and (b). Figs. 9(a) and (b) are schematic diagrams for explaining 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 M30 (an example of the "separating means" in this application) for lifting the coating gun G. The lifting device M30 is a power cylinder, and includes a cylinder tube M31, a piston rod M32 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. In addition, 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 a gas or liquid such as oil serving as a power source is supplied and discharged through the pipe, thereby enabling the piston rod M32 to advance and retreat relative to the cylinder tube M31. The lifting device M30 moves the piston rod M32 forward and backward relative to the cylinder tube M31 to rotate the arm M33 and the coating gun G connected thereto, thereby switching between a state in which the discharge port N of the coating gun G is in contact with 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 a coated state of the hot melt adhesive H, and FIG. 9(b) is a schematic diagram showing a non-coated state of the hot melt adhesive H. In the coating method according to this modified example, in the non-coated state, the coating 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 the hot melt adhesive H is switched from the coated state to the non-coated 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 (b). Figs. 10(a) and (b) are schematic diagrams for explaining 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" in the present application) for lifting the coating gun G in the vertical direction. The lifting device M40 has a motor M41, a pinion gear M42 fixed to the rotating shaft of the motor 41, and a rack gear M43 meshing 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 lifting 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 coating gun G is raised by the lifting device M40 to separate the discharge port N from the sheet material S.

[0045] Fig. 10(a) is a schematic diagram showing a coated state of hot melt adhesive H, and Fig. 10(b) is a schematic diagram showing a non-coated state of hot melt adhesive H. In the coating method according to this modified example, in the coated state, the coating gun G is lowered to bring the discharge port N into contact with the sheet material S, and in the non-coated state, the coating 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 the hot melt adhesive H is switched from the coated state to the non-coated state.

[0046] <Example 6> A coating method according to Example 6 will be described with reference to Figs. 11(a) and (b). Figs. 11(a) and (b) are schematic diagrams for explaining 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 at a position facing the discharge port N on the lower side 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 sucking the sheet material S with the suction device M2.

[0047] 11(a) is a schematic diagram showing a state where the discharge port N is in contact with the sheet material S in a coating state of the hot melt adhesive H, and FIG. 11(b) is a schematic diagram showing a state where the discharge port N is separated from the sheet material S in a coating state of the hot melt adhesive H. In the coating method according to this embodiment, the discharge port N is brought into contact with the sheet material S in a coating 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 a coating 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 a coating state, and makes it possible to prevent the hot melt adhesive H from accumulating on the downstream side of the discharge port in the conveying direction.

[0048] The coating method according to this embodiment can employ any of the above-mentioned 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 on the downstream side of the discharge port in the conveying 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 a non-coating area in the design.

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

[0050] FIG. 12 is a flow chart 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 coated on the sheet material (step S201, an example of the "first step" in the present application). Next, in the coated state of the hot melt adhesive H, pressure is applied from below to the sheet material to filter out the hot melt adhesive H accumulated on the downstream side of the discharge port (step S202, an example of the "second step" in the present application). Next, in the coated state of the hot melt adhesive H, the sheet material is separated from the discharge port (step S203, an example of the "third step" in the present application). In the coating method according to the present embodiment, steps S201 to S203 are repeatedly performed once or a plurality of times to prevent the hot melt adhesive H from accumulating on the downstream side of the discharge port in the conveying direction. In the application method according to the present embodiment, after steps S201 to S203 are repeated once or a plurality of 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 certain 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-mentioned Example 1, the coating gun G has a discharge port N for discharging the hot melt adhesive H. Also, 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. Also, 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 the first embodiment will be described with reference to Figs. 13(a)-(c). Figs. 13(a)-(c) are schematic diagrams for explaining the coating method according to the present embodiment. The upper part of Figs. 13(a)-(c) is a schematic diagram of the sheet material S viewed from above, and the lower part of Figs. 13(a)-(c) is a schematic diagram of the sheet material S viewed from the side. The coating device used in the coating method according to the present embodiment includes a coating gun G and a roller R10 (an example of the "filtering means" in the present application). The roller R10 is located below the sheet material S, and the center of rotation O is located downstream of the discharge port N, and is movable up and down. The roller R10 rotates in synchronization with the conveying speed of the sheet material S in the conveying direction of the sheet material S (the direction indicated by the arrow A2).

[0053] 13(a) shows the process of applying hot melt adhesive H. In this process, roller R10 contacts sheet material S at a predetermined position, and the 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 contacting 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 in the applied state of the hot melt adhesive H. This makes it possible to prevent the hot melt adhesive H from accumulating downstream of the discharge port in the conveyance direction, and to prevent the hot melt adhesive H from being applied to a non-applied area designed by the manufacturer.

[0055] 13(c) shows a process of separating the sheet material S from the discharge port N in a non-applied state of the hot melt adhesive H after the hot melt adhesive H has been filtered out. 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 on the downstream side of the discharge port in the conveying direction, even if the hot melt adhesive H could not be completely filtered out in the previous process, and prevents the hot melt adhesive H from being applied to the designed non-applied area.

[0056] <Example 2> A coating method according to Example 2 will be described with reference to Figs. 14(a)-(c). Figs. 14(a)-(c) are schematic diagrams for explaining the coating method according to this embodiment. The upper parts of Figs. 14(a)-(c) are schematic diagrams of the sheet material S viewed from above, and the lower parts of Figs. 14(a)-(c) are schematic diagrams of the sheet material S viewed from the side. The coating device used in the coating method according to this embodiment includes a coating gun G and a roller R20 (an example of the "filtering means" in this application). The roller R20 is located below the sheet material S, and the center of rotation O is located downstream of the discharge port N. The roller 20 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 enlarged diameter portion R22 that is enlarged in diameter than the circumferential portion R21, and a reduced diameter portion R23 that is reduced in diameter than the circumferential portion R21. The enlarged diameter portion R22 applies pressure to the sheet material S by contacting the sheet material S, and filters out the hot melt adhesive H that has accumulated on the downstream side of the discharge port N. The distance between the outer periphery of the enlarged diameter portion R22 and the rotation center of the roller R20 is set to a length that applies sufficient pressure to the sheet material S. The reduced diameter portion R23 is disposed so as to face the sheet material S side after the enlarged diameter portion R22. The distance between the outer periphery of the reduced diameter 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 when the reduced diameter portion R23 faces the sheet material S side.

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

[0059] 14(b) shows the process of filtering out the hot melt adhesive H. In this process, the expanded diameter portion R22 contacts the sheet material S, and the hot melt adhesive H that has accumulated on the downstream side of the discharge port N can be filtered out by applying pressure to the sheet material S with the expanded diameter portion R22. This allows the hot melt adhesive H that has accumulated on the downstream side of the discharge port N to be filtered out in the applied state of the hot melt adhesive H. This prevents the hot melt adhesive H from accumulating on the downstream side of the discharge port in the conveying direction, and prevents the hot melt adhesive H from being applied to a non-applied area designed in advance.

[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 not designated for application by the design.

[0061] <Example 3> A coating method according to Example 3 will be described with reference to Figs. 15(a)-(b). Figs. 15(a)-(b) are schematic diagrams for explaining the coating method according to this example. The upper part of Figs. 15(a)-(b) is a schematic diagram of a sheet material S viewed from above, and the lower part of Figs. 15(a)-(b) is a schematic diagram of a 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" 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 from the blower M3 onto the sheet material S from below, 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 a coating state to a non-coating state. This prevents the coating gun G from dragging the hot melt adhesive H in the non-coating state, and prevents the hot melt adhesive H from being coated in a non-coating range designed by the designer.

[0064] The coating method according to this embodiment can employ any of the above-mentioned 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 on the downstream side of the discharge port in the conveying 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 a non-coating area in the design.

[0065] In the above embodiment, the hot melt adhesive H may be blended with an indicator material that changes color when it comes into 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 back sheet. The indicator material may be a moisture-detecting material or a pH-reactive material. 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 indicator non-placement area, so that the indicator can be placed within the design range. This allows the indicator to be placed within the design range of the absorbent article, so that the indicator can be prevented from becoming an obstacle in 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 far as possible. [Explanation of symbols]

[0067] A1, A2... Arrows C1, C3, C4: Circumferential section C2 · Flat part G·· Application 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 constant 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 separating the discharge port from the workpiece in the coating state; The coating method comprising:

2. a roller that rotates in a conveying direction of the workpiece in synchronization with a conveying speed of the workpiece is disposed below the workpiece and upstream of the discharge port; The roller has a circumferential portion and a flat portion, In the first step, the workpiece is aligned along the circumferential portion to bring the discharge port into contact with the workpiece; In the second step, the object to be coated is aligned along the flat portion to separate the object to be coated from the discharge port. The coating method according to claim 1 .

3. a roller is disposed above the workpiece and upstream of the discharge port, the roller rotating in a conveying direction of the workpiece in synchronization with a conveying speed of the workpiece; the roller has a circumferential portion corresponding to a length of a non-applying area of ​​the hot melt adhesive on the workpiece, The radius of the circumferential portion is longer than the distance from the rotation center of the roller to the sheet material, In the first step, the roller and the object to be coated are not in contact with each other, thereby bringing the discharge port into contact with the object to be coated; In the second step, the circumferential portion presses down the workpiece to separate the workpiece from the discharge port. The coating method according to claim 1 .

4. a roller that rotates in a conveying direction of the workpiece in synchronization with a conveying speed of the workpiece is disposed below the workpiece so as to face the discharge port; The roller has a protrusion and a recess, In the first step, the protrusion faces the discharge port, thereby bringing the discharge port into contact with the workpiece, In the second step, the recess faces the discharge port, thereby separating the workpiece from the discharge port. The coating method according to claim 1 .

5. A lifting device is provided to lift the application 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 raised to separate the workpiece from the discharge port. The coating method according to claim 1 .

6. A coating method for intermittently coating a hot melt adhesive from a coating gun onto a substrate being transported in a constant direction, comprising: The application gun has a discharge port for discharging the hot melt adhesive, In a coating state in which the hot melt adhesive is applied to the workpiece, the discharge port is A first step of contacting the substrate with the coating agent; a second step of applying pressure from below to the workpiece in the coating state to filter out the hot melt adhesive accumulated downstream of the discharge port; The coating method comprising:

7. a roller that is movable up and down is disposed below the workpiece and downstream of the discharge port, the roller rotating in a conveying direction of the workpiece in synchronization with a conveying speed of the workpiece; In the first step, the roller is in contact with the workpiece at a predetermined position, In the second step, the roller contacts the workpiece above the predetermined position to apply pressure to the workpiece, thereby 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 6.

8. a roller is disposed below the workpiece and downstream of the discharge port, the roller rotating in a conveying direction of the workpiece in synchronization with a 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 substrate; an enlarged diameter portion having a diameter larger than that of the circumferential portion, the enlarged diameter portion applying pressure to the workpiece and filtering out the hot melt adhesive accumulated downstream of the discharge port; A reduced diameter portion having a smaller diameter than the circumferential portion and arranged so as to face the workpiece side rearward of the enlarged diameter portion; having In the first step, the workpiece is aligned along the circumferential portion to bring the discharge port into contact with the workpiece; In the second step, the hot melt adhesive accumulated downstream of the discharge port is filtered out by applying pressure to the workpiece by the enlarged 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 6.

9. In the second step, the hot melt adhesive is filtered out by blowing compressed air onto the workpiece from below the workpiece. The coating method according to claim 6.

10. The substrate is a sheet material for absorbent articles, 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 9.

11. A coating device that intermittently coats a hot melt adhesive from a coating gun onto a coating object that is transported in a constant direction, The coating 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 separating means for separating the discharge port from the workpiece in the coating state; The coating device comprises:

12. Hot melt adhesive is intermittently applied from an application gun to the workpiece being transported in a certain direction. A coating device comprising: The coating 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 workpiece from below in the coating state; The coating device comprises:

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