JP7714873B2 - Coating method and coating device - Google Patents

Description

The present invention relates to a coating method and a coating device.

In the manufacturing process of absorbent articles such as disposable diapers, urine pads, and sanitary products, hot melt adhesive is intermittently applied to a substrate, such as a sheet material, which is transported in a certain direction (see, for example, Patent Document 1).

JP 2011-131162 A

Hot melt adhesive is applied to the workpiece by heating and melting the solid raw material from an application gun. The hot melt adhesive is applied with the application gun's nozzle in contact with the workpiece. Because hot melt adhesive has a high viscosity even in a molten state, there is a risk that any hot melt adhesive that does not fully deposit on the sheet material will accumulate downstream in the conveyance direction from the application gun's nozzle. When applying hot melt adhesive intermittently, if hot melt adhesive accumulates downstream in the conveyance direction from the nozzle, the application gun will drag the accumulated hot melt adhesive, causing a tailing, and hot melt adhesive will be applied to areas that are not designed to receive hot melt adhesive.

The present invention aims to provide technology that can prevent hot melt adhesive from being applied to areas that are not intended for application.

To solve the above problem, the present invention provides a process for separating the discharge port from the workpiece while the hot melt adhesive is being applied.

In more detail, the present invention relates to a coating method in which a hot melt adhesive is intermittently applied from a coating gun to a workpiece being transported in a fixed direction. The coating gun has a discharge port for discharging the hot melt adhesive, and includes a first step of bringing the discharge port 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 discharge port away from the workpiece in the coating state.

In the above coating method, a roller is disposed below the workpiece and upstream of the discharge outlet, rotating in the transport direction of the workpiece in synchronization with the transport speed of the workpiece. 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.

In the above coating method, a roller is arranged above 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 radius of the circumferential part of the roller is longer than the distance from the center of rotation of the roller to the workpiece , and in the first step, the roller and the workpiece are kept out of contact with each other, thereby bringing the discharge outlet into contact with the workpiece, and in the second step, the workpiece is pushed down by the circumferential part, thereby separating the workpiece from the discharge outlet.

In the above coating method, a roller that rotates in the conveying direction of the workpiece in synchronization with the conveying 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 convex 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.

In the above coating method, a lifting device may be provided to raise and lower the coating gun in the vertical direction, and in the first step, the coating gun may be lowered to bring the discharge port into contact with the workpiece, and in the second step, the coating gun may be raised to separate the workpiece from the discharge port.

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 port for discharging the hot melt adhesive, and the method may include a first step of bringing the discharge port 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 port.

In the above coating method, a vertically movable roller is disposed below the workpiece and downstream of the discharge port, rotating in the transport direction of the workpiece in synchronization with the transport speed of the workpiece; in the first step, the roller contacts the workpiece at a predetermined position; in the second step, the roller contacts the workpiece above the predetermined position, thereby applying pressure to the workpiece and filtering out the hot melt adhesive that has accumulated downstream of the discharge port; and the coating method may also include a third step in which the roller is lowered in the coated state to separate the workpiece from the discharge port.

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. The roller has a circumferential portion corresponding to the length of the area where the hot melt adhesive is to be applied to the workpiece, an enlarged diameter portion larger in diameter than the circumferential portion, which applies pressure to the workpiece and filters out the hot melt adhesive that has accumulated downstream of the discharge port, and a reduced diameter portion smaller in diameter than the circumferential portion, which applies pressure to the workpiece and filters out the hot melt adhesive that has accumulated downstream of the discharge port. and a reduced diameter section 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 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 in which, in the coated state, the reduced diameter section is directed toward the object to be coated, thereby separating the object from the discharge port.

In the above coating method, in the second step, the hot melt adhesive may be filtered out by blowing compressed air onto the object from below.

In the above application method, the substrate may be a sheet material for absorbent articles, and the hot melt adhesive may contain a material that changes color upon contact with excrement.

The present invention can also be viewed from the perspective of an application device. For example, the present invention may 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 a discharge port for discharging the hot melt adhesive, the application gun bringing the discharge port into contact with the workpiece in an application 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 application state.

The present invention also provides 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 a discharge port for discharging the hot melt adhesive, the application gun bringing the discharge port 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 discharge port.

This invention prevents hot melt adhesive from being applied to areas not intended for application.

FIG. 1 is a schematic diagram showing a coating method according to a comparative example. FIG. 2 is a flowchart showing an outline of the coating method according to the first embodiment. FIG. 3 is a schematic diagram showing a coating method according to Example 1 of the first embodiment. FIG. 4 is a schematic diagram showing a coating method according to Example 2 of Embodiment 1. FIG. 5 is a schematic diagram showing a coating method according to Example 3 of Embodiment 1. FIG. 6 is a schematic diagram showing a coating method according to Example 4 of Embodiment 1. FIG. 7 is a schematic diagram showing a coating method according to Example 5 of Embodiment 1. FIG. 8 is a schematic diagram showing a coating method according to Modification 1 of Example 5 of Embodiment 1. FIG. 9 is a schematic diagram showing a coating method according to Modification 2 of Example 5 of Embodiment 1. FIG. 10 is a schematic diagram showing a coating method according to Modification 3 of Example 5 of Embodiment 1. FIG. 11 is a schematic diagram showing a coating method according to Example 6 of Embodiment 1. FIG. 12 is a flowchart showing an outline of the coating method of the second embodiment. FIG. 13 is a schematic diagram showing a coating method according to Example 1 of the second embodiment. FIG. 14 is a schematic diagram showing a coating method according to Example 2 of Embodiment 2. FIG. 15 is a schematic diagram showing a coating method according to Example 3 of Embodiment 2.

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

<Overview of application method>
The application method according to this embodiment intermittently applies a hot melt adhesive from an application gun to a substrate being conveyed in a fixed direction. Examples of substrates include sheet materials used for absorbent articles such as disposable diapers, urine pads, and sanitary napkins. In a production line for producing absorbent articles, a hot melt adhesive is applied to a sheet material being conveyed in a fixed direction. The hot melt adhesive may be applied intermittently to a designed application area (hereinafter referred to as the "application area") but not to a designed non-application area (hereinafter referred to as the "non-application area"). The application area and the non-application area are continuous in the conveyance direction of the sheet material. The hot melt adhesive is dispensed from the application gun when the application area of the sheet material passes under the application gun, and the hot melt adhesive is not dispensed from the application gun when the non-application area of the sheet material passes under the application gun. This allows the hot melt adhesive to be intermittently applied to a sheet material being conveyed in a fixed direction.

In addition, 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 applying hot melt adhesive without bringing the nozzle of the application gun into contact with the sheet material, the hot melt adhesive is applied by spraying, which makes it difficult to apply the hot melt adhesive smoothly 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 it is necessary to provide a non-adhesive area 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.

In addition, in the application method according to this embodiment, the hot melt adhesive is applied from an application gun to the sheet material in a melted state by heating the solid raw material to approximately 140°C to 160°C. Because hot melt adhesive has a high viscosity even in a molten state, there is a risk that any hot melt adhesive that does not completely adhere to the sheet material will accumulate downstream in the conveyance direction from the application gun's discharge port.

Figure 1 is a schematic diagram showing a coating method according to a comparative example. The upper part of Figure 1 is a schematic diagram of the sheet material S, which is the object to be coated, viewed from above, and the lower part of Figure 1 is a schematic diagram of the sheet material S viewed from the side. The sheet material S is transported in the direction indicated by arrow A1 in Figure 1 by roller R100, which rotates in the direction indicated by arrow A2 in Figure 1. 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, the comparative example uses a contact-type coating gun G in which the discharge port N is constantly in contact with the sheet material.

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 is not dispensed. However, tailing occurs, in which the application gun G drags the hot melt adhesive H that has accumulated downstream of the discharge port N in the conveying direction, and hot melt adhesive H is applied to the non-application area as well. Thus, when hot melt adhesive H is intermittently applied with the discharge port N of the application gun G constantly in contact with the sheet material S, tailing occurs, in which the application gun G drags the hot melt adhesive H, and 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 tailing by raising the temperature of the hot melt adhesive H above 160°C, thereby reducing the viscosity of the hot melt adhesive H. However, raising the temperature of the hot melt adhesive H above 160°C is undesirable because it may alter the performance of the hot melt adhesive.

<Embodiment 1>
First, a coating method according to embodiment 1 will be described. In the coating method according to this embodiment, the discharge port of the coating gun is separated from the sheet material when the hot melt adhesive is being applied to the sheet material. This prevents the hot melt adhesive from accumulating downstream in the conveyance direction of the discharge port. The coating method according to this embodiment prevents the coating gun from dragging the hot melt adhesive when the hot melt adhesive is not being applied, thereby preventing the hot melt adhesive from being applied to areas not designed for application.

Figure 2 is a flowchart outlining the coating method according to this embodiment. In this coating method, first, the discharge port is brought into contact with the sheet material while the hot melt adhesive H is being applied to the sheet material (step S101, an example of the "first step" herein). Next, the discharge port is separated from the sheet material while the hot melt adhesive H is being applied (step S102, an example of the "second step" herein). The coating method according to this embodiment prevents hot melt adhesive H from accumulating downstream of the discharge port in the conveying direction by repeating steps S101 and S102 one or more times. The coating method according to this embodiment can intermittently apply hot melt adhesive H to a sheet material being conveyed in a certain direction by switching the hot melt adhesive H to a non-applied state after repeating steps S101 and S102 one or more times.

Next, the coating method according to this embodiment will be described in more detail with reference to Figures 3 to 8. Six specific examples, Examples 1 to 6, are illustrated in this embodiment. As shown in Figures 3 to 8, in this embodiment, the coating gun G has a discharge port N that discharges hot melt adhesive H. Raw material for 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 with 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 Figures 3 to 8, the sheet material is transported in the direction indicated by arrow A1 in each figure.

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.

Figure 3(a) is a schematic diagram showing the state in which the discharge port N is in contact with the sheet material S when hot melt adhesive H is being applied, and Figure 3(b) is a schematic diagram showing the state in which the discharge port N is separated from the sheet material S when hot melt adhesive H is being applied. The roller R1 has a circumferential portion C1 and a flat portion C2. In the application method of 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 when applied, and the sheet material S is separated from the discharge port N by aligning the sheet material S along the flat portion C2 when applied. 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 when applied, preventing hot melt adhesive H from accumulating downstream of the discharge port in the conveying direction.

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.

4A is a schematic diagram showing a state in which the discharge port N is in contact with the sheet material S during application of the hot melt adhesive H, and FIG. 4B is a schematic diagram showing a state in which the discharge port N is separated from the sheet material S during application 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 application 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 application state, the sheet material S is separated from the discharge port N by pressing down the sheet material S with the circumferential portion C3. 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, preventing the hot melt adhesive H from accumulating downstream in the conveyance direction of the discharge port.

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.

5A 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. 5B 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 R3 has a convex portion D1 and a concave portion D2. In the coating method according to this embodiment, the convex portion D1 faces the discharge port N in the coating state, thereby bringing the discharge port N into contact with the sheet material S, and the concave portion D2 faces the discharge port N in the coating state, thereby separating the sheet material S from the discharge port N. 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, thereby preventing the hot melt adhesive H from accumulating downstream of the discharge port in the conveyance direction.

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.

Figure 6(a) is a schematic diagram showing the state in which the discharge port N is in contact with the sheet material S when hot melt adhesive H is being applied, and Figure 6(b) is a schematic diagram showing the state in which the discharge port N is separated from the sheet material S when hot melt adhesive H is being applied. 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 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 R42. In the application method of 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 when applied, and the sheet material S is separated from the discharge port N by aligning the sheet material S along the separation portion D3 when applied. This allows the discharge port N to contact the sheet material S and then separate the sheet material S from the discharge port N once or multiple times during application, preventing hot melt adhesive H from accumulating downstream of the discharge port in the conveying direction.

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 herein) 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.

Figure 7(a) is a schematic diagram showing the state in which the discharge port N is in contact with the sheet material S when hot melt adhesive H is being applied, and Figure 7(b) is a schematic diagram showing the state in which the discharge port N is separated from the sheet material S when hot melt adhesive H is being applied. In the application method of 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 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 hot melt adhesive H from accumulating downstream of the discharge port in the conveying direction.

<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.

Figure 8(a) is a schematic diagram showing the state in which hot melt adhesive H has been applied, and Figure 8(b) is a schematic diagram showing the state in which hot melt adhesive H has not been applied. In the application method of 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.

<Modification 2 of Example 5>
A coating method according to Modification 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 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" 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 about 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 about 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 is supplied and discharged through the pipe as a power source, 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 thereby switching 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.

Figure 9(a) is a schematic diagram showing the state in which hot melt adhesive H is applied, and Figure 9(b) is a schematic diagram showing the state in which hot melt adhesive H is not applied. In the application method of 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.

<Modification 3 of Example 5>
A coating method according to Modification 3 of Example 5 will be described with reference to FIGS. 10A and 10B. FIGS. 10A and 10B 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 herein) that lifts and lowers the coating gun G in the vertical direction. The lifting device M40 includes 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 coating gun G is raised by the lifting device M40, thereby separating the discharge port N from the sheet material S.

Figure 10(a) is a schematic diagram showing the state in which hot melt adhesive H has been applied, and Figure 10(b) is a schematic diagram showing the state in which hot melt adhesive H has not been applied. In the application method of 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.

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.

Figure 11(a) is a schematic diagram showing the state in which the discharge port N is in contact with the sheet material S when hot melt adhesive H is being applied, and Figure 11(b) is a schematic diagram showing the state in which the discharge port N is separated from the sheet material S when hot melt adhesive H is being applied. In the application method of this embodiment, the discharge port N is brought into contact with the sheet material S when hot melt adhesive H is being applied, and the sheet material S is separated from the discharge port N by sucking the sheet material S with a suction device M when hot melt adhesive H is being applied. 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 when hot melt adhesive H is being applied, preventing hot melt adhesive H from accumulating downstream of the discharge port in the conveying direction.

The application method according to this embodiment can employ any of the above examples. The application method according to each example of this embodiment can prevent hot melt adhesive H from accumulating downstream of the discharge port in the conveying direction and can 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 designed for application.

<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.

Figure 12 is a flowchart outlining the coating method according to this embodiment. In this coating method, first, hot melt adhesive H is applied to a sheet material (step S201, an example of the "first step" herein). Next, while the hot melt adhesive H is being applied, pressure is applied to the sheet material from below to filter out any hot melt adhesive H that has accumulated downstream of the discharge port (step S202, an example of the "second step" herein). Next, while the hot melt adhesive H is being applied, the sheet material is separated from the discharge port (step S203, an example of the "third step" herein). The coating method according to this embodiment prevents hot melt adhesive H from accumulating downstream of the discharge port in the conveying direction by repeatedly performing steps S201 to S203 one or more times. In the application method according to this embodiment, steps S201 to S203 are repeated one or more times, and then the hot melt adhesive H is placed in a non-application state, allowing the hot melt adhesive H to be intermittently applied to a sheet material being transported in a fixed direction. Note that step S203 can be omitted.

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

Example 1
The coating method according to Example 1 will be described with reference to FIGS. 13(a) to 13(c). FIGS. 13(a) to 13(c) are schematic diagrams illustrating the coating method according to this example. The upper parts of FIGS. 13(a) to 13(c) are schematic diagrams illustrating the sheet material S as viewed from above, and the lower parts of FIGS. 13(a) to 13(c) are schematic diagrams illustrating the sheet material S as 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 herein). 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.

Figure 13(a) shows the process of applying hot melt adhesive H. In this process, roller R10 contacts sheet material S at a predetermined position, with discharge port N 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 the height at which sheet material S is optimally positioned relative to discharge port N when hot melt adhesive H is applied.

Figure 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 it above a predetermined position, 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 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 conveying direction, and prevents the hot melt adhesive H from being applied to areas not designated for application.

Figure 13(c) shows the process of separating the sheet material S from the discharge outlet N after the hot melt adhesive H has been filtered out and in a state where no hot melt adhesive H has been applied. In this process, the roller R10 is lowered to separate the sheet material S from the discharge outlet N. This process prevents the hot melt adhesive H from accumulating downstream of the discharge outlet in the conveying direction, even if all of the hot melt adhesive H was not filtered out in the previous process, and prevents the hot melt adhesive H from being applied to areas not intended for application.

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

The roller R20 has a circumferential portion R21, an enlarged-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 enlarged-diameter portion R22 applies pressure to the sheet material S by contacting it, filtering out the hot melt adhesive H that has accumulated downstream of the discharge port N. The distance between the outer periphery of the enlarged-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 enlarged-diameter portion R22 so that it faces 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.

Figure 14(a) shows the process of applying hot melt adhesive H. In this process, the sheet material S is placed along the circumferential portion R21 of the roller R20, bringing the discharge port N 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.

Figure 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 by applying pressure to the sheet material S with the expanded diameter portion R22, the hot melt adhesive H that has accumulated downstream of the discharge port N can be filtered out. This allows the hot melt adhesive H that has accumulated downstream of the discharge port N to be filtered out 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 conveying direction, and prevents the hot melt adhesive H from being applied to areas not designated for application.

14(c) shows the process of separating the sheet material S from the discharge port N after filtering out the hot melt adhesive H and in a state where the hot melt adhesive H is not being applied. 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 designed for application.

Example 3
A coating method according to Example 3 will be described with reference to Figures 15(a) and 15(b). Figures 15(a) and 15(b) are schematic diagrams illustrating the coating method according to this example. The upper parts of Figures 15(a) and 15(b) are schematic diagrams of the sheet material S viewed from above, and the lower parts of Figures 15(a) and 15(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 herein). The air blower M3 is disposed below the sheet material S and blows compressed air toward the downstream side of the discharge port N.

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

Figure 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, 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 for application.

The application method according to this embodiment can employ any of the above examples. The application method according to each example of this embodiment can prevent hot melt adhesive H from accumulating downstream of the discharge port in the conveying direction and can 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 designed for application.

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 area where 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 hot melt adhesive H blended with the indicator material to the skin-facing side of the backsheet. The indicator material may be a moisture-sensing 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 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.

<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.

A1, A2...Arrows C1, C3, C4...Circumferential portion C2...Flat portion G...Application gun H...Hot melt adhesive M1, M20, M30, 40...Lifting device M2...Suction device M3...Air blower N...Discharge port R1, R2, R3, R4, R10, R20, R100...Roller S...Sheet material

Claims (7)

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 separating the discharge port from the object to be coated 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 coating the hot melt adhesive in the coating area of the workpiece, and intermittently coating the hot melt adhesive in such a way that the hot melt adhesive is not applied to the non-coating area of the workpiece .
Application method. 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 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 object to be coated is placed along the flat portion to separate the object to be coated from the discharge port.
The coating method according to claim 1 . a roller that rotates in a conveying direction of the workpiece in synchronization with a conveying speed of the workpiece is disposed above the workpiece and upstream of the discharge port;
the radius of the circumferential portion of the roller is longer than the distance from the rotation center of the roller to the object to be coated;
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 object to be coated, thereby separating the object to be coated from the discharge port.
The coating method according to claim 1 . a roller that rotates in the conveying direction of the object to be coated in synchronization with the conveying speed of the object to be coated so as to face the discharge port below the object to be coated;
The roller has a protrusion and a recess,
In the first step, the convex portion faces the discharge port, thereby bringing the discharge port into contact with the object to be coated,
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 . A lifting device is provided to lift the application gun up and down,
In the first step, the coating gun is lowered to bring the discharge port into contact with the object to be coated,
In the second step, the coating gun is raised to separate the workpiece from the discharge port.
The coating method according to claim 1 . 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 5. 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 separating means for separating the discharge port from the object to be coated 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,
The application gun repeats once or a plurality of times a step of bringing the discharge port into contact with the workpiece in the application state and a step of moving the discharge port away from the workpiece, and then switches to a non-application state in which the hot melt adhesive is not discharged from the discharge port , thereby applying the hot melt adhesive to the application area of the workpiece and intermittently applying the hot melt adhesive while not applying the hot melt adhesive to the non-application area of the workpiece .
Coating equipment.