Manufacturing method of fused sheet body

Abstract

To provide a method for efficiently manufacturing a sheet fusion body with a desired shape by using a laser beam.SOLUTION: A method for manufacturing a sheet fusion body of the present invention comprises: 1) a sheet laminating step in which a plurality of sheets 2, 3 are stacked to form a sheet laminate 11 having overlapping portions 12 of fiber surfaces; 2) a close contact portion formation step in which a close contact portion 13 in which the plurality of sheets 2, 3 are peelably in close contact with each other on the sheet laminate 11; and 3) a laser beam irradiation step in which a seal edge portion 5 is formed by irradiating the sheet laminate 11, in which the close contact portion 13 is formed, with a laser beam 41 L in a desired pattern with the sheet laminate 11 being in a non-pressurized state.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for producing a fused sheet product using laser light. [Background technology]

[0002] Known sheet fusion products have a laminated structure of multiple sheets, and have a sealed edge formed by fusing the edges of the multiple sheets together at the edges of the laminated structure. For example, a bag-shaped container made of a resin film corresponds to this. Such sheet fusion products have conventionally been produced by stacking multiple sheets to obtain a sheet laminate, applying pressure to the sheet laminate at a location where the sealed edge is to be formed and heating the sheet laminate, and then cutting the sealed edge with a cutting blade. Patent Document 1 describes the production of gloves, a type of sheet fusion product, by this conventional production method.

[0003] Patent Document 2 describes a method for manufacturing a sheet fusion product made of multiple synthetic resin films, which includes the steps of clamping predetermined portions of overlapping synthetic resin films between a pair of clamping members, at least one of which is heated to a predetermined temperature lower than the melting point of the films, to releasably adhere the films to each other, and cutting the predetermined adhered portions with a heated cutting blade, thereby simultaneously performing cutting and welding sealing.

[0004] In conventional methods for producing fused sheets, such as those described in Patent Documents 1 and 2, a sealed portion is formed by heating a sheet laminate while clamping the fusion-targeted portion with clamping members. Therefore, changing the shape of the sealed portion may require changing the clamping members, making it difficult to change the shape of the sealed portion. Thus, conventional methods for producing fused sheets have a problem in that they have limited flexibility in the shape of the sealed portion and are unable to fully meet various requirements regarding the shape of the sealed portion. Patent Document 3 describes a plastic film welding method that can solve this problem, which includes a step of irradiating laser light onto the surfaces of multiple plastic films pressed between a pair of pressure rolls to form a welded portion. Patent Document 3 specifically discloses a technology for welding multiple plastic films together by irradiating them with laser light, but does not disclose melt-cutting by laser light irradiation.

[0005] Patent Document 4 describes a method for manufacturing a pants-type wearing article in which side seal portions of the pants-type wearing article are formed using laser light. Specifically, in the manufacturing method described in Patent Document 4, a portion of a sheet laminate (a laminate of an outer body on the front body side and an outer body on the back body side) where a side seal portion is to be formed is pressurized, and then laser light is irradiated onto the portion, thereby dividing the multiple sheets and fusing together the cut edges of the stacked sheets resulting from the dividing to form the side seal portion. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-047972 [Patent Document 2] Japanese Patent Application Publication No. 10-86223 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-255461 [Patent Document 4] Japanese Patent Application Laid-Open No. 2015-8943 Summary of the Invention [Problem to be solved by the invention]

[0007] The technology for fusing a sheet laminate by irradiating it with a laser beam described in Patent Document 4 employs a method in which a sheet laminate to be fused is sandwiched between a support member and a press member, and a laser beam is irradiated onto the sheet laminate from an opening provided in one of the support member and press member, resulting in a problem that there is a low degree of freedom in the irradiation pattern of the laser beam, and therefore a low degree of freedom in the shape (contour) of the fused sheet body, which is the object to be manufactured. A technology for efficiently manufacturing a fused sheet body of a desired shape has not yet been provided.

[0008] The present invention relates to a method for efficiently producing a fused sheet body of a desired shape using a laser beam. [Means for solving the problem]

[0009] The present invention provides a method for producing a fused sheet body having a laminated structure of multiple sheets, with sealed edges at the edges of the laminated structure where the edges of the multiple sheets are fused together, and at least one surface of each of the multiple sheets is a fibrous surface made of fibers containing a thermoplastic resin. One embodiment of the method for producing a fused sheet of the present invention includes a sheet stacking step of stacking the plurality of sheets to form a sheet stack having overlapping portions between the fiber surfaces. In one embodiment of the method for producing a fused sheet body of the present invention, a contact portion forming step is provided in which a contact portion is formed in the sheet laminate where the plurality of sheets are releasably adhered to each other. One embodiment of the method for manufacturing a fused sheet body of the present invention includes a laser light irradiation step in which the sheet laminate having the adhesive portion formed thereon is in an unpressurized state and laser light is irradiated onto the sheet laminate in a desired pattern to melt-cut the sheet laminate and fuse the cut edges of the multiple sheets produced by the melt-cutting together, thereby forming the sealed edge portion in the portion of the sheet laminate irradiated with the laser light. In one embodiment of the method for producing a fused sheet body of the present invention, the method further comprises a cutting step of cutting the sheet laminate along the contour of the fused sheet body to be produced. Other features, advantages and embodiments of the present invention are described below. [Effects of the Invention]

[0010] According to the present invention, a fused sheet body having a desired shape can be efficiently produced using a laser beam. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a plan view schematically showing one side of a glove, which is one embodiment of a sheet fused product produced by the production method of the present invention. [Figure 2] FIG. 2 is an explanatory diagram of a method for producing the fused sheet body shown in FIG. [Figure 3] Figure 3 is a drawing substitute photograph of the interface between multiple sheets in a pressed portion of a sheet laminate having overlapping fiber surfaces after the overlapping portion of the sheet laminate has been pressed with a predetermined pressing force. Figure 3(a) shows the state in which a tightly adhered portion has been formed in which the multiple sheets are tightly adhered to each other in a peelable manner, and Figure 3(b) shows the state in which no tightly adhered portion has been formed. [Figure 4] FIG. 4 is an explanatory diagram of a method for capturing the photograph shown in FIG. [Figure 5] Figure 5(a) is a cross-sectional view schematically showing a cross section along the thickness direction of an example of a sheet laminate in which a sealed portion is formed, and Figure 5(b) is a cross-sectional view schematically showing the state in which a sealed edge portion is formed by irradiating laser light onto the sheet laminate shown in Figure 5(a). [Figure 6] FIG. 6 is an explanatory diagram of another embodiment of the method for producing a fused sheet body of the present invention. [Figure 7] FIG. 7 is an explanatory view (corresponding to FIG. 2) of still another embodiment of the method for producing a fused sheet body of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described below based on preferred embodiments with reference to the drawings. The same parts in the drawings are designated by the same reference numerals. The drawings are essentially schematic, and the dimensions and dimensional ratios of certain parts to other parts may differ from those of the actual product.

[0013] Fig. 1 shows a glove 1 which is one embodiment of a fused sheet product manufactured by the manufacturing method of the present invention. Glove 1 has a laminated structure 4 of multiple sheets 2 and 3, and has a sealed edge 5 at the edge of the laminated structure 4 where the edges of the multiple sheets 2 and 3 are fused together. The sealed edge 5 includes a fused portion 5M of the multiple sheets 2 and 3.

[0014] In this embodiment, glove 1 is a pouch having a sealed edge 5 and a non-bonded portion 6 surrounded by the sealed edge 5, and has five pouches corresponding to five fingers. Laminated structure 4 is a two-layer structure consisting of sheet 2 forming one side of glove 1 (the back of the hand) and sheet 3 forming the other side (the palm of the hand), and is composed of sealed edge 5 and non-bonded portion 6. The multiple sheets 2 and 3 constituting laminated structure 4 are bonded to each other by fusion at sealed edge 5 but are not bonded to each other at non-bonded portion 6, and are overlapped in a peelable manner. The portion of non-bonded portion 6 located at the edge of laminated structure 4 is an opening 7 used to insert a hand when putting on glove 1. A hand inserted through opening 7 is placed in non-bonded portion 6.

[0015] At least one surface of each of the multiple sheets 2 and 3 is a fiber surface composed of fibers (thermoplastic fibers) containing a thermoplastic resin. The fiber surface is a surface composed mainly of fibers and has fine irregularities due to the fibers. For example, a film made of a synthetic resin such as an olefin-based resin does not contain fibers and has a smooth surface, in contrast to the fiber surface. In the present invention, the multiple sheets constituting the sheet fusion product, which is the production target, are used with the fiber surface because, as will be described later, fiber sheets closely related to the desired effect of the present invention (efficient production of a sheet fusion product of a desired shape using laser light) include, for example, nonwoven fabrics, woven fabrics, and paper. Typical examples of nonwoven fabrics include nonwoven fabrics produced by known methods such as the air-through method, spunbonding method, spunlace method, and electrospinning method. Sheets 2 and 3 typically consist solely of fiber sheets, but may also be composite sheets having a laminate structure of a fiber sheet and a sheet other than a fiber sheet (e.g., a resin film). In this case, the inner surface of the glove 1 (the surface that comes into contact with the hand inserted through the opening 7) is made of a fiber sheet, and the outer surface of the glove 1 is made of a sheet other than the fiber sheet.

[0016] Next, the method for manufacturing a sheet fusion product of the present invention will be described with reference to the drawings, taking the above-mentioned method for manufacturing glove 1 as an example. Fig. 2 shows a schematic configuration of the method for manufacturing glove 1. The upper part of Fig. 2 shows a schematic configuration of a manufacturing apparatus 10 used to carry out the method for manufacturing glove 1, and the lower part of Fig. 2 shows how raw materials (sheets 2, 3) are made into an intermediate product (sheet laminate 11) and then into a sheet fusion product (glove 1) in the manufacturing apparatus 10. The manufacturing apparatus 10 conveys the workpiece (raw material or intermediate product) in one predetermined direction, and performs processing steps including a sheet laminate forming step, a contact portion forming step, and a laser light irradiation step using the workpiece during the conveyance, thereby manufacturing a glove 1, which is a sheet fusion body to be manufactured. In this embodiment, the workpiece is the sheets 2 and 3 which are the raw material of the glove 1, or an intermediate product (sheet laminate 11) obtained by processing the raw material, and both the raw material and the intermediate product are in the form of a long continuous belt extending in one direction, and MD coincides with the longitudinal direction of the workpiece.

[0017] In this specification, "MD" indicates the machine direction in which a workpiece is conveyed, and "CD" indicates the cross machine direction perpendicular to the MD.

[0018] As shown in FIG. 2, the manufacturing apparatus 10 includes, from the upstream side to the downstream side of the MD, a sheet laminate forming unit 20, a contact portion forming unit 30, a laser light irradiation unit 40, and a cutting unit 50, in this order.

[0019] The sheet laminate forming unit 20 is an apparatus for performing the sheet laminate forming step, which is one of the essential steps of the manufacturing method of the present invention, and includes a sheet supplying means 21 and a pair of rolls 22 and 23. In this embodiment, two sheets 2 and 3 are used as raw materials for the glove 1. The sheets 2 and 3 are each a long, continuous strip that extends in one direction and are wound into rolls 2R and 3R before use. The sheet laminate forming unit 20 continuously pays out the sheets 2 and 3 from the raw rolls 2R and 3R using the sheet supplying means 21, and introduces the paid-out sheets 2 and 3 between the pair of rolls 22 and 23 to join them, thereby forming a sheet laminate 11, which is an intermediate product of the glove 1. The configuration of each part of the sheet laminate forming unit 20 is the same as that of parts having similar functions in this type of sheet processing apparatus.

[0020] The contact portion forming unit 30 is an apparatus for performing the contact portion forming step, which is one of the essential steps of the manufacturing method of the present invention, and includes an intermittent pressing means 31. The intermittent pressing means 31 includes a pair of non-roll-shaped pressing tools 32 and 33. Each of the pressing tools 32 and 33 has a flat pressing surface that contacts and presses the workpiece (sheet laminate 11). The pressing tools 32 and 33 are arranged on both sides (upper and lower in the illustrated embodiment) of the workpiece, sandwiching it therebetween, and are arranged so as to be able to move toward and away from the workpiece. When not in use, each of the pair of pressing tools 32 and 33 waits at a predetermined standby position spaced apart from the workpiece. When in use (to press the workpiece), it moves from the standby position to a predetermined pressing position (a position closer to the workpiece than the standby position) to press the workpiece. The sheet stack 11, which is the workpiece, is pressed simultaneously from both sides in the thickness direction by the pair of pressing tools 32, 33, thereby forming a contact portion 13 in the sheet stack 11. The contact portion 13 will be described later.

[0021] The laser light irradiation unit 40 is an apparatus that performs the laser light irradiation step, which is one of the essential steps in the manufacturing method of the present invention, and includes a laser light irradiator 41 that irradiates the workpiece (sheet stack 11) with laser light 41L, and a conveying means 42 that supports the sheet stack 11 from the side opposite to the side irradiated with the laser light and conveys the sheet stack 11 to the MD. The conveying means 42 is configured similarly to a known belt conveyor. The laser light irradiator 41 is capable of arbitrarily moving the irradiation position while irradiating laser light. The laser light preferably has an oscillation wavelength that is absorbed by at least one of the sheets constituting the sheet stack 11 and can cause that sheet to generate heat. Examples of laser light that can be used in the present invention include CO2 lasers, YAG lasers, LD lasers (semiconductor lasers), YVO4 lasers, and fiber lasers.

[0022] The cutting unit 50 is an apparatus for carrying out a continuous body cutting step that can be adopted in the manufacturing method of the present invention. In this embodiment, the sheet laminate 11, which is the workpiece, is a continuous body consisting of a plurality of fused-sheet bodies (gloves 1) or intermediate products thereof connected in one direction MD, so a step (continuous body cutting step) of cutting the continuous body to produce single gloves 1 shown in Fig. 1 is required. The cutting section 50 includes a cutter roll 51, an anvil roll 52 disposed opposite the circumferential surface of the cutter roll 51, a transfer roll 53 disposed opposite the circumferential surface of the anvil roll 52, and a conveying means 54. The cutter roll 51 is a contact-type cutting means having blades 51a on its circumferential surface that come into contact with and cut the workpiece. The anvil roll 52 and the transfer roll 53 are each configured to be able to suction and hold the workpiece on its circumferential surface. The conveying means 54 is configured similarly to a known belt conveyor.

[0023] Here, the technical concept of the present invention will be explained. The problem to be solved by the present invention is to provide a method for efficiently producing a fused sheet body having a desired shape using a laser beam. For example, the method for producing a fused sheet body (a pants-type wearing article having side seal portions) described in Patent Document 4 involves irradiating a sheet stack with laser light to separate the sheets that make up the sheet stack, and then fusing the cut edges of the stacked sheets resulting from the separation to form sealed edges (side seal portions), as described above.Since the sheet stack is fused and cut at the same time, the fused sheet body can be produced efficiently. On the other hand, in the manufacturing method described in Patent Document 4, in the laser beam irradiation step, the sheet laminate to be fused is clamped between a support member and a pressurizing member to be pressed, and laser beam is irradiated toward the sheet laminate through an opening provided in one of the two members. Therefore, the shape of the opening must correspond to the irradiation pattern of the laser beam. Therefore, the manufacturing method described in Patent Document 4 is sufficient as long as the irradiation pattern (trajectory) of the laser beam is a simple pattern consisting of only straight lines. However, if the pattern is relatively complex, with many irregularities, such as the outline of glove 1 shown in Figure 1, it becomes more difficult to manufacture the corresponding opening. This makes it difficult to manufacture a fused sheet body with a relatively complex outline, such as glove 1, as designed, and limits the shapes of the fused sheet body that can be manufactured. Furthermore, the manufacturing method described in Patent Document 4 has the problem that, since the shape of the opening must be changed when the irradiation pattern of the laser beam is changed, it is not easy to change the irradiation pattern of the laser beam, and it is difficult to smoothly change the shape of the fused sheet body. Therefore, in the manufacturing method described in Patent Document 4, in order to increase the flexibility of the laser beam irradiation pattern, it is conceivable to irradiate the sheet stack to be fused with laser beam in an unpressurized state by, for example, not using the pressurizing member during the laser beam irradiation process. However, it has been found that simply placing the sheet stack to be fused in an unpressurized state results in insufficient fusion of the cut edges of the multiple sheets caused by the laser beam irradiation, resulting in problems such as failure to form a sealed edge or a significant decrease in the fusion strength of the sealed edge. This problem is presumably due to the fact that, in an unpressurized sheet stack, the multiple sheets constituting the sheet stack are not in close contact with each other, making it difficult for the molten material of the sheet-forming material that forms near the irradiated area with laser beam to penetrate through the surrounding fibers. The molten material is generated when the sheet-forming material, such as a thermoplastic resin, is heated by the laser beam and serves as an adhesive that bonds the cut edges of the multiple sheets that form the sealed edge. To form a sealed edge with sufficient fusion strength for practical use, it is important to appropriately control the amount and position of the molten material.

[0024] The present invention has been made in view of the above problems of the conventional technology, and the following configurations 1 to 3 can be mentioned as its main features (means for solving the problems). Configuration 1: A sheet laminate is formed by using multiple sheets with fibrous surfaces and stacking the fibrous surfaces together. Configuration 2: Before irradiating the sheet laminate with laser light, a tightly adhered portion is formed in the sheet laminate where a plurality of sheets are tightly adhered to each other in a peelable manner. Configuration 3: A laser beam is irradiated onto the sheet stack in an unpressurized state.

[0025] By adopting the above-mentioned configuration 3, equipment for pressing the sheet laminate in the laser beam irradiation step (for example, the pressing member in the manufacturing method described in Patent Document 4) becomes unnecessary, so that the degree of freedom in the laser beam irradiation pattern is greatly improved and basically there is no restriction on the laser beam irradiation pattern, making it possible to manufacture a fused sheet body of a desired shape. On the other hand, as mentioned above, by adopting the configuration 3, the sheets constituting the sheet laminate are not in close contact with each other during laser light irradiation, which raises concerns that the cut edges of the sheets may not be sufficiently fused together. In contrast, the present invention eliminates this concern by adopting the configurations 1 and 2. That is, the present invention employs the configuration 1 to form a sheet laminate by overlapping the fiber surfaces of the sheets, and the configuration 2 to form a close contact portion in the sheet laminate before the laser light irradiation step by, for example, pressing the sheet laminate, so that the close contact portion is maintained even when the sheet laminate is in an unpressurized state during the laser light irradiation step. When laser light is irradiated onto the adhesive portion of such a sheet laminate while the sheet laminate is in an unpressurized state, the molten sheet-forming material (such as a thermoplastic resin) produced near the area irradiated by the laser light penetrates from the irradiated area through the fibers of the adhesive portion over a relatively wide area, creating a state similar to that in which adhesive has been applied over a fairly wide area including the irradiated area of ​​the sheet laminate, and a sealed edge is obtained in which the cut edges of multiple sheets are fused together with a practically sufficient fusion strength. Therefore, according to the present invention having the above-mentioned configurations 1 to 3, a fused sheet body having a desired shape can be efficiently produced using a laser beam.

[0026] The "adhesion portion" in Feature 2 is a portion where the "fiber surfaces" in Feature 1 are in close contact with each other. The multiple sheets constituting the sheet laminate are not bonded to each other, but are releasably adhered via the fiber surfaces, for example, by entanglement of the fibers constituting the fiber surfaces. The "releasably adhered" state referred to here refers to a state in which the sheets are in such close contact that they can be peeled off without being damaged when peeled off from the sheet laminate. The adhesion portion is not formed by simply stacking the fiber surfaces of multiple sheets on top of each other, but is formed, for example, by pressing the multiple sheets (sheet laminate) in the thickness direction while the fiber surfaces of the multiple sheets are stacked on top of each other. In the adhesion portion forming step, which is one of the essential steps in the manufacturing method of the present invention, the adhesion portion is typically formed in the sheet laminate by pressing the sheet laminate.

[0027] From the viewpoint of reliably forming the adhesive portion in the sheet laminate, it is preferable that the constituent fibers (fibers containing a thermoplastic resin) of the fiber surface of the sheets constituting the sheet laminate are thin. Generally, thin fibers with a small fiber diameter have a relatively low bending rigidity and are easily deformed, so that the fiber surfaces containing such fibers are easily entangled, and the adhesive portion is easily formed. On the other hand, if the fiber diameter of the constituent fibers of the fiber surface is too small, productivity may decrease. In consideration of the above, the average fiber diameter of the constituent fibers (fibers containing a thermoplastic resin) of the fiber surface of the sheets constituting the sheet laminate is preferably 0.3 to 3 μm, more preferably 0.4 to 2 μm.

[0028] The average fiber diameter of the constituent fibers of the fiber surface of the sheet is measured by the following method. 200 fibers are randomly selected from the fiber surface of the sheet to be measured, and for each fiber, a straight line extending perpendicular to the longitudinal direction (diameter direction) is drawn. The radial length of the part of the line that overlaps with the fiber is measured, and this measurement value is taken as the fiber diameter of the fiber. The arithmetic mean value of the fiber diameters of the 200 fibers measured in this way is calculated, and this is taken as the average fiber diameter of the constituent fibers of the fiber surface of the sheet.

[0029] The manufacturing method of the glove 1 reflects the technical concept of the present invention described above. The manufacturing method of the glove 1 will be described below with reference to FIG.

[0030] In the method for manufacturing the glove 1, first, a plurality of sheets 2 and 3 are stacked to form a sheet laminate 11 having overlapping portions 12 between fiber surfaces (sheet laminate formation step).

[0031] In the manufacturing apparatus 10, as shown in FIG. 2, continuous strip sheets 2 and 3 are fed from raw rolls 2R and 3R by a sheet supply means 21, and are joined in the gap between a pair of rolls 22 and 23 so that their fiber surfaces face each other, thereby forming a continuous strip sheet laminate 11 (sheet laminate formation process).

[0032] During the period from the completion of the sheet stack forming step (immediately after the sheet stack 11 passes through the sheet stack forming section 20) to the completion of the next step, the close-contact portion forming step (before the sheet stack 11 is introduced into the close-contact portion forming section 30), the sheets 2 and 3 constituting the sheet stack 11 are simply overlapped, and the above-mentioned "close-contact portion where the sheets 2 and 3 are releasably adhered to each other" is not formed in the overlapping portion 12 of the fiber surfaces. In other words, during this period, the entire overlapping portion 12 of the sheet stack 11 is a non-adhesion portion, as shown in FIG. 2. In the sheet stack forming process, the sheets 2 and 3, which are the raw materials for the sheet stack 11, are simply stacked, and the sheet stack 11 is not substantially pressed. The length of the gap between the pair of rolls 22 and 23 (the length along the thickness direction of the workpiece) is adjusted so as not to substantially press the sheets 2 and 3 (workpiece) introduced into the gap. Here, "substantially not pressing" includes 1) a mode in which the workpiece is not pressed, i.e., the pressing force is zero, and 2) a mode in which the workpiece is pressed with a pressing force that does not result in the formation of the adhered portion. In the mode 2), the pressing force that does not result in the formation of the adhered portion is preferably less than 1 MPa. This pressing force of less than 1 MPa is approximately the same as the pressing force (nip pressure) exerted on the sheet by a pair of rolls in a typical sheet conveying device having a mechanism for conveying a sheet while sandwiching it between the rolls.

[0033] In the method for manufacturing the glove 1, next, a contact portion 13 is formed in the sheet laminate 11 where the sheets 2, 3 are releasably adhered to each other (contact portion forming step).

[0034] In the manufacturing apparatus 10, the sheet stack 11 is pressed to form the bonded portion 13. Specifically, as shown in Fig. 2, the sheet stack 11 having the overlapping portion 12 between the fiber surfaces is introduced into an intermittent pressing means 31, and pressed in the thickness direction by a pair of pressing tools 32, 3, thereby forming at least a part of the overlapping portion 12 into the bonded portion 13 where the multiple sheets 2, 3 are bonded to each other in a peelable manner (bonded portion forming step).

[0035] In this embodiment, the sheet stack 11 (a continuous body in which intermediate products of a plurality of fused-sheet bodies 1 are connected in one direction) is conveyed intermittently, and while the conveyance of the sheet stack 11 is stopped, the sheet stack 11 is pressed by an intermittent pressing means 31 (a pair of pressing tools 32, 33). That is, in this embodiment, the sheet stack 11 is intermittently pressed to form a contact portion 13 in the sheet stack 11. Specifically, in this embodiment, the sheet stack 11 is conveyed to the MD, and when a region to be pressed (a region to form a contact portion) of the sheet stack 11 is introduced into the gap between the pair of pressing tools 32, 33, the conveyance of the sheet stack 11 is stopped, and the pair of pressing tools 32, 33, which are waiting at predetermined standby positions, are moved to predetermined pressing positions to press the region to be pressed, thereby forming the contact portion 13. Thereafter, the pair of pressing tools 32, 33 are moved from the pressing position to the standby position, and the conveyance of the sheet stack 11 is resumed. In this embodiment, the sheet laminate 11 is subjected to intermittent pressing by repeating a series of operations of "conveying the sheet laminate 11 → stopping → pressing (forming the adhered portion 13)" as described above, and the adhered portion 13 is formed in a desired portion of the sheet laminate 11. In this embodiment, the conveyance of the plurality of sheets 2 and 3, which are the raw materials for the sheet laminate 11, is linked to the conveyance of the sheet laminate 11, and while the conveyance of the sheet laminate 11 is stopped, the conveyance of the plurality of sheets 2 and 3 is also stopped. Note that when intermittent pressing is performed on the sheet laminate 11, the conveyance of the plurality of sheets 2 and 3 does not need to be intermittent, and they may be continuously conveyed, for example, by using a known accumulation mechanism.

[0036] In this embodiment, as shown in FIG. 2, the entire area of ​​the overlapping portion 12 between the fiber surfaces of the plurality of sheets 2, 3 is made into a tightly adhered portion 13 where the plurality of sheets 2, 3 are tightly adhered to each other so as to be peelable. Furthermore, in this embodiment, the CD length of the pressing surface (surface in contact with the workpiece) of each of the pair of pressing tools 32, 33 is longer than the CD length of the sheet stack 11, which is the workpiece, so that a single pressing operation of the pressing tools 32, 33 (movement from the standby position to the pressing position on the workpiece, pressing the workpiece, and movement from the workpiece to the standby position) can press the entire portion of the sheet stack 11 located between the pressing tools 32, 33. That is, in this embodiment, a single pressing operation can form the adhesion portion 13 over the entire intended pressing area of ​​the sheet stack 11.

[0037] In the adhesion portion forming step, the pressure (pressing force) when pressing the sheet laminate 11 is preferably 1 MPa or more, more preferably 10 MPa or more, from the viewpoint of more reliably forming the adhesion portion 13. On the other hand, if the pressing force is too large, there is a concern that peeling of the adhesion portion 13 may become difficult, so from the viewpoint of preventing this, the pressing force is preferably 50 MPa or less, more preferably 40 MPa or less. From the same viewpoint as above, the pressing time (the time during which a predetermined pressing force is maintained) is preferably 0.01 seconds or more, more preferably 0.1 seconds or more, and preferably 30 seconds or less, more preferably 20 seconds or less.

[0038] Fig. 3 shows a photograph of the interface between multiple sheets in a pressed portion of a sheet laminate having overlapping fiber surfaces after the overlapping portion of the sheet laminate has been pressed with a predetermined pressing force. The sheet laminate that is the subject of the photograph in Fig. 3 is a sheet laminate 11 in which a portion of the sheet laminate 11 before the formation of the contact portion 13 has been pressed with a predetermined pressing force, and the basic configuration of the subject is the same as that of the sheet laminate 11. The procedure for obtaining the photograph in Fig. 3 is as follows. First, two sheets 2 and 3 are stacked to form a sheet laminate 11 having an overlapping portion 12 between their fiber surfaces. Next, as shown in FIG. 4, a portion of the overlapping portion 12 is pressed with a predetermined pressing force to form a pressed portion P1. Then, a region P2 spanning the pressed portion P1 and its surrounding non-pressed portion is cut out from the sheet laminate 11 as an object. The two sheets 2 and 3 overlapping at the pressed portion P1 in the object (region P2) are peeled off, and a region P3 including the interface (fiber surfaces) between the two sheets 2 and 3 is imaged using an electron microscope. The planar shape and size of region P2 are not particularly limited, but it can be, for example, a rectangular shape with a short side length of 5 mm and a long side length of 10 mm. The photograph in FIG. 3 was taken using a scanning electron microscope (JEOL Ltd., "JSM-6510"). In addition, both sheets 2 and 3 in the drawing substitute photograph of FIG. 3 are made of polypropylene fibers with a fiber diameter of 0.9 μm and a basis weight of 5 g / m 2 It is a nonwoven fabric. The subject in Figure 3(a) and the subject in Figure 3(b) have different pressing forces applied to the overlapping portion 12 in the process of forming the pressed portion P1: the pressing force for the subject in Figure 3(a) is 10 MPa, and the pressing force for the subject in Figure 3(b) is 1 MPa. For both subjects, the pressing time in the process of forming the pressed portion P1 is 1 second, and the heating temperature is 25°C. In Figure 3(a), there are areas where the sheets 2 and 3 are in close contact with each other via their fiber surfaces, whereas in Figure 3(b), there are essentially no areas where the sheets 2 and 3 are in close contact with each other, and a relatively large gap (black area) exists at the interface between the sheets 2 and 3. From this, it can be seen that in order to reliably form the contact portion 13 by pressing the overlapping portion 12 of the sheet stack 11 in the contact portion forming process, the pressing force on the overlapping portion 12 is not sufficient if it is about the nip pressure (less than 1 MPa) used for sheet transport in a typical sheet transport device, and it is preferable to press the overlapping portion 12 with a pressing force that exceeds this nip pressure (for example, 1 MPa or more).

[0039] In the close-contact portion forming step, the sheet laminate 11 may simply be pressed. Alternatively, the close-contact portion 13 may be formed by pressing the sheet laminate 11 while heating it at a temperature below the melting point of the thermoplastic resin (the material forming the fibers of the sheets 2 and 3) contained in the sheet laminate 11. This may facilitate and ensure the formation of the close-contact portion 13. Here, "easily forming the close-contact portion 13" refers to the fact that pressing while heating allows the close-contact portion 13 to be formed with lower surface pressure or in a shorter time than pressing without heating. According to the inventors' findings, for example, when the sheets constituting the sheet laminate are spunbonded nonwoven fabrics or through-air nonwoven fabrics, simply pressing the sheet laminate makes it difficult to form close-contact portions in which the fiber surfaces of the sheets are releasably adhered to each other. Therefore, when such nonwoven fabrics are used as the raw material for the fused sheet body, the close-contact portion forming step is preferably performed while heating it at a temperature below the melting point of the thermoplastic resin forming the nonwoven fabric. When the sheet laminate 11 contains multiple types of thermoplastic resins with different melting points, specifically, for example, when the types of thermoplastic resin differ between the multiple sheets 2, 3, it is preferable to heat and press the sheet laminate 11 at a temperature below the melting point of the thermoplastic resin with the lowest melting point among the multiple types of thermoplastic resin.

[0040] The heating temperature when pressing the sheet laminate in the adhesion portion forming step may be adjusted appropriately depending on the type of thermoplastic resin contained in the sheet laminate, and is not particularly limited. However, when the thermoplastic resin is one that is commonly used as a material for nonwoven fabrics, specifically, for example, when the thermoplastic resin contains polypropylene, the heating temperature is preferably 50°C or higher, more preferably 100°C or higher, and preferably 150°C or lower, more preferably 140°C or lower. The "heating temperature" referred to here refers to the product temperature of the sheets constituting the sheet laminate. The product temperature of the sheets is typically the same as the heating temperature set by the heating means for heating the sheet laminate. As the heating means, any known means that can be used for this type of so-called heat press can be used without any particular limitation. For example, a heating means such as a heater may be built into one or both of the pair of pressing tools 32, 33 of the intermittent pressing means 31, and the sheet laminate 11 may be heated by the heating means while the pressing tools 32, 33 are pressing the sheet laminate 11. Alternatively, a heating means such as a heater may be arranged upstream of the intermittent pressing means 31 in the MD, and the sheet laminate 11 may be heated by the heating means prior to pressing by the pair of pressing tools 32, 33.

[0041] In the manufacturing method of the glove 1, next, the sheet laminate 11 having the formed tight-fitting portion 13 is put in a non-pressurized state, and laser light is irradiated to the sheet laminate 11 in a desired pattern to melt-cut the sheet laminate 11 and fuse the cut edges of the multiple sheets 2, 3 produced by the melt-cutting together, thereby forming a sealed edge portion 5 in the portion of the sheet laminate 11 irradiated with the laser light (laser light irradiation process).

[0042] In the manufacturing apparatus 10, as shown in FIG. 2, the sheet laminate 11 is introduced onto the workpiece placement surface in the conveying means 42 of the laser light irradiation section 40, and laser light 41L is irradiated onto the sheet laminate 11 from a laser light irradiator 41 arranged opposite the placement surface, thereby forming a seal edge portion 5 having a shape corresponding to the contour of the glove 1 in the contact portion 13 of the sheet laminate 11 (laser light irradiation process).

[0043] When a sheet laminate 11 having a contact portion 13 as shown in FIG. 5(a) is irradiated with laser light, a portion of the material (such as a thermoplastic resin) forming the irradiated portion of the laser light generates heat, vaporizes, and disappears, cutting (melting) the irradiated portion as shown in FIG. 5(b), generating cut edges of the sheets 2 and 3. The cut edges are then heated by the laser light, forming fused portions 5M near the irradiated portions. Thus, a sealed edge portion 5 is formed in which the cut edges of the sheets 2 and 3 are joined together by the fused portions 5M. At this time, as described above, the vicinity of the irradiated portion of the laser light melts as a result of being heated by the laser light, and the molten material permeates a relatively wide area from the irradiated portion through the fibers of the contact portion 13, thereby strengthening the fusion of the cut edges of the sheets 2 and 3 at the sealed edge portion 5. The laser light irradiation process is a process of cutting (melting) the workpiece (sheet laminate 11) using a non-contact cutting means called a laser light irradiator, which cuts the workpiece without coming into contact with the workpiece, and can also be called a cutting process.

[0044] After the laser beam irradiation step, the sheet laminate 11 is divided into a glove 1 (fused sheet body) consisting of a portion surrounded by the sealed edge portion 5 and the remaining unnecessary portion 9, as shown in Fig. 2. In this embodiment, in the laser beam irradiation step, a sealed edge portion 5 corresponding to only a portion of the outline of the glove 1, which is the object of manufacture, is formed in the sheet laminate 11, and the other portion of the outline of the glove 1 is not irradiated with laser beam. Therefore, after the laser beam irradiation step is performed and before the next continuous cutting step is performed, neither the glove 1 nor the unnecessary portion 9 is cut off from the sheet laminate 11.

[0045] In this embodiment, the workpiece, a sheet laminate 11, is a continuous body in which multiple gloves 1 (fused sheets) or intermediate products thereof are connected in one direction MD. Therefore, a process (continuous body cutting process) is performed to cut the continuous body to produce individual gloves 1. Specifically, as shown in FIG. 2, the continuous strip-shaped sheet laminate 11 having a sealed edge 5 formed thereon and passing through a laser beam irradiation unit 40 is introduced into a cutting unit 50, where it is cut into a length corresponding to one unit of product by a cutter roll 51, thereby continuously producing multiple individual gloves 1. In FIG. 2, a linear cutting line 8 extending in the CD indicates the location cut by a blade 51a of the cutter roll 51. By cutting the sheet laminate 11 along the cutting line 8, the sheet laminate 11 is separated into gloves 1 or intermediate products (products) and unnecessary portions 9 (non-products). The gloves 1 or intermediate products are transported to a subsequent process, such as a packaging process, by a transport means 54, and the unnecessary portions 9 are collected via a separate route. The method for recovering the unnecessary portion 9 can be any method conventionally used in this type of production line for recovering unnecessary portions generated when cutting a workpiece. The method for producing a sheet fused body of the present invention may include a step of recovering such unnecessary portions. 2, in this embodiment, the cutting line 8 is not continuous over the entire CD length of the sheet laminate 11. That is, in this embodiment, the sheet laminate 11 is not cut over the entire CD length at the cutting section 50, and both CD ends of the sheet laminate 11 are not cut. This is to ensure the continuity of the MD of the sheet laminate 11 after cutting, taking into consideration the ease of transporting the sheet laminate 11 and the ease of collecting the unnecessary portion 9.

[0046] Other embodiments of the present invention will be described below. In the other embodiments described below, the configurations different from the above embodiment will be mainly described, and the same configurations as in the above embodiment will be assigned the same reference numerals as in the above embodiment and will not be described again. For the configurations not specifically described in the embodiments described below, the description of the above embodiment will be applied as appropriate.

[0047] In the above embodiment, the sheet laminate 11 is intermittently pressed to form the adhesive portion 13 in the sheet laminate 11, but in the present invention, the method for performing the adhesive portion forming step (the method for pressing the sheet laminate) is not particularly limited, and may be, for example, a continuous pressing method. Figure 6 shows the main parts of a manufacturing apparatus 10A that performs the adhesive portion forming step by a continuous pressing method.

[0048] The manufacturing apparatus 10A differs from the manufacturing apparatus 10 having the intermittent pressing means 31 as the close-contact portion forming unit 30 in that the manufacturing apparatus 10A has the continuous pressing means 35 as the close-contact portion forming unit 30. The manufacturing apparatus 10A also differs from the manufacturing apparatus 10 having the sheet stacking step in that the manufacturing apparatus 10A does not have dedicated equipment for performing the sheet stacking step, such as the sheet stack forming unit 20. In the manufacturing apparatus 10A, the close-contact portion forming unit 30 (continuous pressing means 35) performs the sheet stacking step and the close-contact portion forming step. The continuous pressing means 35 includes a sheet supplying means 34 and a pair of pressing rolls 36 and 37. The sheet supplying means 34 is configured similarly to the sheet supplying means 21 provided in the manufacturing apparatus 10. The pressing rolls 36 and 37 each have a pressing surface that comes into contact with the workpiece, which is a circumferential surface (curved surface), which differs from the pressing tools 32 and 33, which have flat pressing surfaces. The pressing rolls 36 and 37 are arranged on both sides (up and down in the illustrated embodiment) of the sheet stack 11, which is the workpiece, and are arranged so that their pressing surfaces are always in contact with the sheet stack 11 during transport.

[0049] In the manufacturing apparatus 10A, as shown in Fig. 6, sheets 2 and 3 are continuously fed from raw rolls 2R and 3R, and the fed sheets 2 and 3 are introduced into a gap (nip portion) between a pair of pressing rolls 36 and 37 and merged to produce a sheet laminate 11 (sheet stacking step), and at the same time, the sheet laminate 11 is pressed in the thickness direction to form a contact portion 13 (contact portion forming step). Furthermore, in the manufacturing apparatus 10A, the sheet laminate 11 is continuously conveyed, and in the portion of the continuous strip-shaped sheet laminate 11 that has passed through the continuous pressing means 35, a contact portion 13 is formed over the entire length in the MD of that portion. The contact portion forming step according to the present invention can also be carried out by such a continuous pressing method, and the desired effects of the present invention can be obtained.

[0050] Fig. 7 shows a manufacturing apparatus 10B which is another embodiment of the manufacturing apparatus for the glove 1. In the manufacturing method of the glove 1 using the manufacturing apparatus 10, in the contact portion forming step, the contact portions 13 are formed all over the sheet laminate 11 having overlapping portions 12 between fiber surfaces (see Fig. 2). However, as shown in Fig. 7, in the contact portion forming step, the contact portions 13 may be formed partially in the sheet laminate 11. That is, the sheet laminate 11 which has undergone the contact portion forming step may contain a mixture of the contact portions 13 and portions where the contact portions 13 are not formed, i.e., overlapping portions 12. In the manufacturing method of the glove 1 using the manufacturing apparatus 10B, the contact portions 13 are formed intermittently in the MD in the sheet laminate 11 in the contact portion forming step, and in the sheet laminate 11 which has undergone the contact portion forming step, the contact portions 13 and the overlapping portions 12 where the contact portions 13 are not formed are alternately arranged in the MD. In the manufacturing method of the glove 1 using the manufacturing apparatus 10B, the laser beam 41L is irradiated so that the irradiated portion (path) of the laser beam 41L indicated by the reference symbol 14 straddles both the tight-contact portion 13 and the overlapping portion 12 (non-contact portion). In the embodiment shown in Fig. 7, the laser beam 41L is irradiated so that the irradiated portion (path) of the laser beam 41L is continuous across both the tight-contact portion 13 and the overlapping portion 12. As a result, the irradiated portion 14 of the tight-contact portion 13 becomes the sealed edge portion 5, but the irradiated portion 14 of the overlapping portion 12 is a portion where the sheets 2 and 3 are not in contact with each other in the sheet laminate 11 in the non-pressurized state, and the cut edges of the sheets 2 and 3 created by the irradiation of the laser beam 41L are not fused together, so the irradiated portion 14 does not become the sealed edge portion 5 but becomes the opening 7 of the glove 1.

[0051] In this way, when laser light is irradiated to both the contact portion 13 and the overlapping portion 12 (non-contact portion) of the sheet laminate 11, the irradiation conditions of the laser light (output, irradiation speed, number of irradiations, etc.) may be different between the contact portion 13 and the overlapping portion 12. Since the energy required to achieve fusion cutting and welding of the irradiated portion by irradiating the contact portion 13 with laser light differs from that required to achieve fusion cutting of the overlapping portion 12 (non-contact portion) by irradiating the overlapping portion 12 with laser light, selecting the irradiation conditions of the laser light according to the purpose makes it possible to more efficiently manufacture a fused sheet body.

[0052] Moreover, the manufacturing apparatus 10B does not have a cutting unit 50. In the manufacturing method of glove 1 using the manufacturing apparatus 10B, in the laser light irradiation step, a sheet laminate 11 (a continuum in which a plurality of fused sheets or intermediate products thereof are connected in one direction MD) is cut by irradiation with laser light to produce individual gloves 1 (fused sheets) (continuous body cutting step). Specifically, the laser light irradiation unit 40 irradiates the sheet laminate 11 with laser light 41L to form a sealed edge portion 5 and an opening 7 corresponding to the entire outline of the glove 1, which is the object of manufacture, and thereby cuts the continuous strip-like sheet laminate 11 into a plurality of individual gloves 1 and the remaining unnecessary portion 9. The individual gloves 1 thus manufactured are transported to the next process, such as a packaging process, by a transport means 42, and the unnecessary portion 9 is collected via a separate route.

[0053] The fused sheet produced by the present invention can be used for a variety of purposes, including the gloves mentioned above, as well as finger cots, tabi socks, hats, joint supports, etc.

[0054] The present invention has been described above based on its preferred embodiments, but the present invention is not limited to the above embodiments and can be modified as appropriate within the scope of the invention. For example, in the above embodiment, a continuous strip-shaped sheet that is long in one direction is used as the raw material for the sheet fusion product (glove 1), but a sheet having a size corresponding to the sheet fusion product to be manufactured may also be used. In the above embodiment, the number of stacked sheets in the sheet laminate was two, but the number of stacked sheets may be three or more. In this case, the sheet laminate has a plurality of overlapping portions (number of stacked sheets minus one) of two sheets adjacent in the thickness direction, which are arranged intermittently in the thickness direction, and at least one of the overlapping portions is an overlapping portion between fiber surfaces.

[0055] In the sealed portion forming step, the sealed portion may be formed by pressing the sheet laminate, which is the workpiece, while applying ultrasonic waves to the sheet laminate. As a means for applying ultrasonic waves to the sheet laminate, a means conventionally used for ultrasonic sealing can be used. [Explanation of symbols]

[0056] 1 Gloves (sheet fused) 2,3 seats 4 Laminated structure 5 Seal edge 10,10A,10B manufacturing equipment 11 Sheet stack 12 Overlapping area of ​​fiber surfaces (non-contact area) 13 Adhesion part 20 Sheet laminate forming section 30 Adhesion forming part 31 Intermittent pressing means 35 Continuous pressing means 40 Laser light irradiation unit 50 Cut section

Claims

1. A method for producing a fused sheet body, the method comprising: a laminated structure of a plurality of sheets; a sealed edge portion at an edge of the laminated structure where edges of the plurality of sheets are fused together; and at least one surface of each of the plurality of sheets is a fiber surface made of fibers containing a thermoplastic resin, a sheet stacking step of stacking the plurality of sheets to form a sheet laminate having overlapping portions between the fiber surfaces; a contact portion forming step of forming contact portions in the sheet laminate where the plurality of sheets are releasably adhered to each other; a laser beam irradiation step of irradiating the sheet stack in which the adhesive portion has been formed with laser beams in a desired pattern with the sheet stack in a non-pressurized state, thereby fusing and bonding the cut edges of the plurality of sheets produced by the fusing, thereby forming a sealed edge portion in the sheet stack at the irradiated portion of the laser beam; Equipped with In the contact portion forming step, the sheet laminate is pressed while being heated at a temperature below the melting point of the thermoplastic resin on the fiber surface that will become the overlapping portion, thereby forming the contact portion.

2. A method for manufacturing a fused sheet body, the fused sheet body having a laminated structure of a plurality of sheets, the edges of the laminated structure having sealed edges formed by fusing edges of the plurality of sheets together, and at least one surface of each of the plurality of sheets being a fiber surface made of fibers containing a thermoplastic resin, comprising: a sheet stacking step of stacking the plurality of sheets to form a sheet laminate having overlapping portions between the fiber surfaces; a contact portion forming step of forming contact portions in the sheet laminate where the plurality of sheets are releasably adhered to each other; a laser beam irradiation step of irradiating the sheet stack in which the adhesive portion has been formed with laser beams in a desired pattern with the sheet stack in a non-pressurized state, thereby fusing and bonding the cut edges of the plurality of sheets produced by the fusing, thereby forming a sealed edge portion in the sheet stack at the irradiated portion of the laser beam; Equipped with In the step of forming the contact portion, the sheet laminate is pressed while applying ultrasonic waves to form the contact portion.

3. A method for manufacturing a fused sheet body, the fused sheet body having a laminated structure of a plurality of sheets, the edges of the laminated structure having sealed edges formed by fusing edges of the plurality of sheets together, and at least one surface of each of the plurality of sheets being a fiber surface made of fibers containing a thermoplastic resin, comprising: a sheet stacking step of stacking the plurality of sheets to form a sheet laminate having overlapping portions between the fiber surfaces; a contact portion forming step of forming contact portions in the sheet laminate where the plurality of sheets are releasably adhered to each other; a laser beam irradiation step of irradiating the sheet stack in which the adhesive portion has been formed with laser beams in a desired pattern with the sheet stack in a non-pressurized state, thereby fusing and bonding the cut edges of the plurality of sheets produced by the fusing, thereby forming a sealed edge portion in the sheet stack at the irradiated portion of the laser beam; Equipped with In the contact portion forming step, the contact portion is partially formed in the sheet laminate, In the laser light irradiation step, the laser light is irradiated so that the irradiated portion of the laser light straddles both the contact portion and the non-contact portion.

4. The method for producing a fused sheet body according to claim 3 , wherein in the contact portion forming step, the contact portion is formed by pressing the sheet stack.

5. The sheet laminate is a continuous body in which a plurality of the fused-sheet bodies or intermediate products thereof are connected in one direction, The method for producing a fused sheet body according to any one of claims 1 to 4, further comprising, after the laser light irradiation step, a continuous body cutting step of cutting the continuous body to produce individual sheets of the fused sheet body.

6. The sheet laminate is a continuous body in which a plurality of the fused-sheet bodies or intermediate products thereof are connected in one direction, The method for producing a fused sheet body according to any one of claims 1 to 4, wherein in the laser light irradiation step, the continuous body is cut by irradiation with laser light to produce the fused sheet body in individual pieces.

7. The method for producing a fused sheet body according to any one of claims 1 to 4, wherein the average fiber diameter of the constituent fibers of the fiber surface is 0.3 to 3 µm.

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