Method for manufacturing sheet fusion 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] As a fused sheet product, there is known a product having a laminated structure of a plurality of sheets, and a sealed edge portion formed by fusing the edges of the laminated structure to each other, such as a bag-shaped container made of a resin film. Conventionally, such a fused sheet product is produced by stacking a plurality of sheets to obtain a sheet laminate, forming a sealed portion by pressing and heating the portion of the sheet laminate where the sealed edge portion is to be formed, and then cutting the sealed portion with a cutting blade. Patent Document 1 describes the production of a glove, which is a type of fused sheet product, by such a 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 adhered predetermined portions with a heated cutting blade, thereby simultaneously performing cutting and fusion sealing.

[0004] In the conventional manufacturing method of a fused sheet body as described in Patent Documents 1 and 2, a sealed portion is formed by heating a sheet laminate while clamping the fusion-targeted portion with a clamping member, and therefore, when changing the shape of the sealed portion, it may be necessary to change the clamping member, and it is not easy to change the shape of the sealed portion. Thus, the conventional manufacturing method of a fused sheet body has a problem that the degree of freedom of the shape of the sealed portion is low and various requests regarding the shape of the sealed portion cannot be fully met. Patent Document 3 describes a plastic film welding method that can solve this problem, which includes a step of forming a welded portion by irradiating a laser beam on the surfaces of multiple plastic films pressed by a pair of pressing rolls. Note that Patent Document 3 specifically discloses a technology for welding multiple plastic films together by irradiating them with a laser beam, and does not disclose melt-cutting by irradiating them with a laser beam.

[0005] Patent Document 4 describes a method for manufacturing a pant-type wearing article in which a side seal portion of the pant-type wearing article is formed by using a laser beam. 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 placed in a pressurized state, and then the portion is irradiated with a laser beam to divide the multiple sheets, and the cut edges of the stacked sheets resulting from the division are fused together to form a side seal portion. [Prior art documents] [Patent documents]

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

[0007] The technology for cutting a sheet laminate by irradiating a laser beam described in Patent Document 4 employs a method in which a sheet laminate to be cut is sandwiched between a supporting member and a pressing member, and a laser beam is irradiated onto the sheet laminate from an opening provided in one of the supporting member and pressing member, resulting in 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 of manufacture. A technology for efficiently manufacturing a fused sheet body of a desired shape has not yet been provided.

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

[0009] The present invention is a method for producing a fused sheet body having a laminated structure of multiple sheets, the edges of the laminated structure having sealed edges 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 composed of fibers containing a thermoplastic resin. One embodiment of the method for producing a fused sheet product of the present invention includes a sheet laminating step of laminating the plurality of sheets to form a sheet laminate having overlapping portions between the fiber faces. In one embodiment of the method for producing a fused sheet body of the present invention, a contact portion forming step is provided in the sheet laminate, where the plurality of sheets are peelably adhered to each other. One embodiment of the method for producing a fused sheet body of the present invention includes a laser light irradiation step in which the sheet laminate having the adhesive portion formed therein is placed in an unpressurized state, and laser light is irradiated to the sheet laminate in a desired pattern to melt the sheet laminate and fuse the cut edges of the multiple sheets produced by the melting 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. Effect of the Invention

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

[0011] [Figure 1] FIG. 1 is a plan view showing one surface of a glove which is one embodiment of a fused sheet produced by the production method of the present invention. [Diagram 2] FIG. 2 is an explanatory diagram of a method for producing the fused sheet body shown in FIG. [Diagram 3] FIG. 3 is a drawing substitute photograph showing 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 is pressed with a specified pressing force, in which FIG. 3(a) shows a state in which a tightly adhered portion has been formed in which the multiple sheets are adhered to each other in a peelable manner, and FIG. 3(b) shows a state in which no tightly adhered portion has been formed. [Figure 4] FIG. 4 is an explanatory diagram of a method for taking the photograph shown in FIG. [Diagram 5] Figure 5(a) is a cross-sectional view showing a schematic 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 showing a schematic state in which a sealed edge portion is formed by irradiating laser light to 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 diagram (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 PREFERRED EMBODIMENTS

[0012] The present invention will be described below based on preferred embodiments with reference to the drawings. Note that common reference numerals are used to designate the same parts in the drawings. The drawings are basically schematic, and the dimensions and dimensional ratios of certain parts to other parts may differ from the actual ones.

[0013] Fig. 1 shows a glove 1 which is an embodiment of a fused sheet product manufactured by the manufacturing method of the present invention. The glove 1 has a laminated structure 4 of a plurality of sheets 2 and 3, and has a sealed edge portion 5 formed by fusing the edges of the plurality of sheets 2 and 3 to each other at the edge of the laminated structure 4. The sealed edge portion 5 includes a fused portion 5M of the plurality of sheets 2 and 3.

[0014] In this embodiment, the glove 1 is a bag having a sealed edge 5 and a non-jointed portion 6 surrounded by the sealed edge 5, and has five small pouches corresponding to five fingers. The laminated structure 4 is a two-layer structure consisting of a sheet 2 forming one side (the side on the back of the hand) of the glove 1 and a sheet 3 forming the other side (the side on the palm side), and is composed of a sealed edge 5 and a non-jointed portion 6. The sheets 2 and 3 constituting the laminated structure 4 are joined to each other by fusion at the sealed edge 5, but are not joined to each other at the non-jointed portion 6 and are overlapped so as to be peelable. The portion located at the edge of the laminated structure 4 in the non-jointed portion 6 is an opening 7 used to insert a hand when putting on the glove 1. The hand inserted from the opening 7 is placed in the non-jointed 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 caused by the fibers. For example, a film made of a synthetic resin such as an olefin resin does not contain fibers and has a smooth surface, which is in contrast to the fiber surface. In the present invention, the reason for using sheets having the fiber surface as the multiple sheets constituting the sheet fusion product, which is the production object, is that, as will be described later, fiber sheets closely related to the expression of the predetermined effect of the present invention (efficiently producing a sheet fusion product of a desired shape using laser light) include, for example, nonwoven fabric, woven fabric, and paper. Typically, it is a nonwoven fabric, and examples of the nonwoven fabrics include nonwoven fabrics produced by known production methods such as the air-through method, the spunbond method, the spunlace method, and the electrospinning method. Each of the sheets 2 and 3 typically consists of only a fiber sheet, but may also be a composite sheet having a laminated structure of a fiber sheet and a sheet other than a fiber sheet (for example, 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 formed of a fiber sheet, and the outer surface of the glove 1 is formed of a sheet other than the fiber sheet.

[0016] Next, the manufacturing method of the sheet fusion product of the present invention will be described with reference to the drawings, taking the manufacturing method of the glove 1 described above as an example. Fig. 2 shows a schematic configuration of the manufacturing method of the glove 1. The upper part of Fig. 2 shows a schematic configuration of a manufacturing apparatus 10 used to carry out the manufacturing method of the glove 1, and the lower part of Fig. 2 shows how the raw materials (sheets 2, 3) are turned into a sheet fusion product (glove 1) through an intermediate product (sheet laminate 11) in the manufacturing apparatus 10. The manufacturing apparatus 10 transports 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 transport to produce the glove 1, which is the sheet fused body to be manufactured. In this embodiment, the workpiece is the sheets 2, 3 which are the raw material of the glove 1, or an intermediate product (sheet laminate 11) obtained by processing the raw material. Both the raw material and the intermediate product are in the form of a long continuous belt in one direction, and the MD coincides with the longitudinal direction of the workpiece.

[0017] In this specification, "MD" indicates the conveying direction (machine direction) of the workpiece, and "CD" indicates the cross machine direction (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 section 20 is an apparatus for carrying out 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, 23. In this embodiment, two sheets 2, 3 are used as raw materials for the glove 1, and the two sheets 2, 3 are each in the form of a long continuous belt in one direction, and are wound into rolls 2R, 3R before use. The sheet laminate forming section 20 continuously pays out the sheets 2, 3 from the raw rolls 2R, 3R by the sheet supplying means 21, and introduces the paid out sheets 2, 3 between the pair of rolls 22, 23 and merges them to form a sheet laminate 11, which is an intermediate product of the glove 1. The configuration of each part of the sheet laminate forming section 20 is the same as that of a similar function in this type of sheet processing device.

[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, 33. The pressing tools 32, 33 each have a flat pressing surface that contacts and presses the workpiece (sheet laminate 11). The pressing tools 32, 33 are arranged on both sides (upper and lower in the illustrated embodiment) of the workpiece, 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, 33 waits at a predetermined standby position spaced apart from the workpiece, and when in use (when pressing 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 a 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 for carrying out a laser light irradiation step, which is one of the essential steps of the manufacturing method of the present invention, and includes a laser light irradiator 41 that irradiates a laser light 41L toward the workpiece (sheet laminate 11), and a conveying means 42 that supports the sheet laminate 11 from the side opposite to the side irradiated with the laser light and conveys the sheet laminate 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 the laser light. The laser light is preferably one having an oscillation wavelength that is absorbed by at least one of the sheets constituting the sheet stack 11 and can cause the one sheet to generate heat. Examples of laser light that can be used in the present invention include CO2 laser, YAG laser, LD laser (semiconductor laser), YVO4 laser, and fiber laser.

[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, since the sheet laminate 11, which is the workpiece, is a continuous body in which a plurality of fused sheet bodies (gloves 1) or intermediate products thereof are connected in one direction MD, a step (continuous body cutting step) of cutting the continuous body to manufacture the single-piece glove 1 shown in Fig. 1 is required. The cutting section 50 includes a cutter roll 51, an anvil roll 52 arranged opposite the peripheral surface of the cutter roll 51, a transfer roll 53 arranged opposite the peripheral surface of the anvil roll 52, and a conveying means 54. The cutter roll 51 is a contact-type cutting means having a blade 51a on its peripheral surface that comes into contact with the workpiece to cut it. The anvil roll 52 and the transfer roll 53 are each configured to be able to suck and hold the workpiece on its peripheral surface. The conveying means 54 is configured in the same manner as a known belt conveyor.

[0023] Here, the technical concept of the present invention will be described. An object of the present invention is to provide a method for efficiently producing a fused sheet body having a desired shape by using a laser beam. For example, the method of manufacturing a fused sheet product (a pants-type wearing article having a side seal portion) described in Patent Document 4 involves irradiating a sheet stack with laser light to divide the multiple sheets that make up the sheet stack, and then fusing the cut edges of the stacked sheets resulting from the cutting to form a sealed edge portion (side seal portion), as described above. Since the sheet stack is fused and cut at the same time, the fused sheet product can be produced efficiently. On the other hand, in the manufacturing method described in Patent Document 4, in the laser light irradiation step, the sheet laminate to be fused is sandwiched between a support member and a pressing member to be in a pressurized state, and the laser light is irradiated toward the sheet laminate from an opening provided in one of the two members, so the shape of the opening needs to correspond to the irradiation pattern of the laser light. Therefore, the manufacturing method described in Patent Document 4 only requires that the irradiation pattern (trajectory) of the laser light is a simple pattern consisting of straight lines, but if the pattern is relatively complex with many irregularities such as the contour of the glove 1 shown in Figure 1, it becomes difficult to manufacture the corresponding opening, so that it may be difficult to manufacture a sheet fusion body with a relatively complex contour such as the glove 1 as designed, and there is a limit to the shape of the sheet fusion body that can be manufactured. In addition, the manufacturing method described in Patent Document 4 has a problem that when the irradiation pattern of the laser light is changed, the shape of the opening needs to be changed, so that it is not easy to change the irradiation pattern of the laser light, and it is not possible to smoothly respond to changes in the shape of the sheet fusion body. Therefore, in the manufacturing method described in Patent Document 4, in order to increase the degree of freedom of the irradiation pattern of the laser light, it is possible to irradiate the sheet laminate to be cut with the laser light in a non-pressurized state by not using the pressing member in the laser light irradiation step. However, it has been found that simply putting the sheet laminate to be cut in a non-pressurized state causes problems such as insufficient fusion of the cut edges of the sheets caused by the laser light irradiation, making it impossible to form a seal edge, or causing a significant decrease in the fusion strength of the seal edge. This problem is presumably due to the fact that in a non-pressurized sheet laminate, the sheets constituting the sheet laminate are not in close contact with each other, so that the molten material of the sheet forming material generated near the irradiated part of the laser light is unlikely to penetrate from the irradiated part through the surrounding fibers. The molten material is generated when the sheet forming material such as a thermoplastic resin is heated by the laser light, and serves as an adhesive that bonds the cut edges of the sheets constituting the seal edge. In order to form a seal edge having 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 consideration of the problems of the conventional technology, and the following configurations 1 to 3 can be mentioned as main features (means for solving the problems) of the present invention. 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 bonding portion is formed in the sheet laminate where a plurality of sheets are bonded to each other in a peelable manner. Configuration 3: Laser light is irradiated onto the sheet laminate 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 of the laser beam irradiation pattern is significantly improved, and basically, there is no restriction on the laser beam irradiation pattern. Therefore, it becomes possible to manufacture a fused sheet body of a desired shape. On the other hand, by adopting the above-mentioned configuration 3, as described above, the sheets constituting the sheet laminate are not in close contact with each other when the laser beam is irradiated, and there is a concern that the fusion of the cut edges of the sheets may be insufficient. In contrast, the present invention dispels this concern by adopting the above-mentioned configurations 1 and 2. That is, the present invention adopts the above-mentioned configuration 1 to form a sheet laminate by overlapping the fiber faces of the sheets, and adopts the above-mentioned configuration 2 to form a close contact part in the sheet laminate before the laser beam irradiation step by pressing the sheet laminate, etc., so that the close contact part is maintained even if the sheet laminate is in a non-pressurized state in the laser beam irradiation step. When laser light is irradiated to 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 in the vicinity of the portion irradiated by the laser light penetrates from the irradiated portion through the fibers of the adhesive portion over a relatively wide area, resulting in a state similar to that in which adhesive has been applied over a fairly wide area including the irradiated portion of the sheet laminate, and a sealed edge is obtained in which the cut edges of multiple sheets are fused together with a fusion strength sufficient for practical use. 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 by using a laser beam.

[0026] The "adhesion part" of the above-mentioned configuration 2 is a part where the "fiber surfaces" of the above-mentioned configuration 1 are in close contact with each other, and although the multiple sheets constituting the sheet laminate are not joined to each other, the fibers constituting the fiber surfaces are intertwined with each other, and so they are in close contact with each other in a peelable manner via the fiber surfaces. The term "peelably adhered" as used herein refers to a state in which the sheets are in close contact to such an extent that they can be peeled off without being damaged when peeled off from the sheet laminate. The adhesion part is not formed by simply stacking the fiber surfaces of multiple sheets on 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 each other. In the adhesion part forming step, which is one of the essential steps of the manufacturing method of the present invention, the sheet laminate is typically pressed to form an adhesion part in 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. In general, fine 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, there is a risk of reducing productivity. 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 in a direction perpendicular to the longitudinal direction (diameter direction) is drawn, and the radial length of the part of the line that overlaps with the fiber is measured, and the measured value is 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 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 above-mentioned technical concept of the present invention. 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, 3 are laminated 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-shaped sheets 2, 3 are fed from raw rolls 2R, 3R by a sheet supplying means 21, and are joined in the gap between a pair of rolls 22, 23 so that their fiber surfaces face each other, thereby forming a continuous strip-shaped sheet laminate 11 (sheet laminate formation process).

[0032] During the period from after the sheet laminate forming step (immediately after the sheet laminate 11 passes through the sheet laminate forming section 20) to before the next step of the contact portion forming step (before the sheet laminate 11 is introduced into the contact portion forming section 30), the sheets 2, 3 constituting the sheet laminate 11 are simply overlapped, and the above-mentioned "contact portion where the sheets 2, 3 are peelably adhered to each other" is not formed in the overlapping portion 12 between the fiber faces. In other words, during this period, the entire overlapping portion 12 of the sheet laminate 11 is a non-adhesive portion, as shown in FIG. 2. In the sheet stack forming process, the sheets 2 and 3, which are the raw materials of 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 form in which the workpiece is not pressed, i.e., the pressing force is zero, and 2) a form in which the workpiece is pressed with a pressing force that does not result in the formation of the adhesion portion. In the form 2), the pressing force that does not result in the formation of the adhesion 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) applied to the sheet by the roll pair in a general sheet conveying device having a mechanism for conveying the sheet while sandwiching it between the roll pair.

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

[0034] In the manufacturing apparatus 10, the sheet stack 11 is pressed to form a contact portion 13. Specifically, as shown in Fig. 2, the sheet stack 11 having an overlapping portion 12 between fiber faces is introduced into an intermittent pressing means 31, and pressed in the thickness direction by a pair of pressing tools 32, 33, to form at least a part of the overlapping portion 12 into a contact portion 13 where the multiple sheets 2, 3 are peelably adhered to each other (contact portion forming process).

[0035] In this embodiment, the sheet laminate 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 laminate 11 is stopped, the sheet laminate 11 is pressed by the intermittent pressing means 31 (a pair of pressing tools 32, 33). That is, in this embodiment, the sheet laminate 11 is intermittently pressed to form the adhesion portion 13 in the sheet laminate 11. Specifically, in this embodiment, the sheet laminate 11 is conveyed to the MD, and when the pressing region (the region to form the adhesion portion) of the sheet laminate 11 is introduced into the gap between the pair of pressing tools 32, 33, the conveyance of the sheet laminate 11 is stopped, and the pair of pressing tools 32, 33 waiting at a predetermined waiting position is moved to a predetermined pressing position to press the pressing region, thereby forming the adhesion portion 13. Thereafter, the pair of pressing tools 32, 33 are moved from the pressing position to the waiting position, and the conveyance of the sheet laminate 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 adhesion portion 13)" in this manner, and the adhesion portion 13 is formed at a desired portion of the sheet laminate 11. In this embodiment, the conveyance of the multiple sheets 2 and 3, which are the raw materials of 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 multiple sheets 2 and 3 is also stopped. Note that when the sheet laminate 11 is subjected to intermittent pressing, the conveyance of the multiple sheets 2 and 3 does not need to be intermittent, and 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 faces of the plurality of sheets 2, 3 is made into a contact portion 13 where the plurality of sheets 2, 3 are in peelable contact with each other. In this embodiment, the CD length of the pressing surface (contact surface 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, and a single pressing operation of the pressing tools 32, 33 (movement from the standby position to the pressing position of 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 in the gap between the pressing tools 32, 33. That is, in this embodiment, a single pressing operation can form the contact portion 13 in 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, and therefore, 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 is preferably 30 seconds or less, more preferably 20 seconds or less.

[0038] Fig. 3 shows a photograph of the interface between a plurality of sheets in a pressed portion of a sheet laminate having an overlapping portion between fiber faces, after the overlapping portion of the sheet laminate is pressed with a predetermined pressing force. The sheet laminate that is the subject of the photograph of Fig. 3 is a sheet laminate 11 in which a part before the formation of the contact portion 13 is pressed with a predetermined pressing force, and the basic structure of the subject is the same as that of the sheet laminate 11. The procedure for obtaining the photograph of 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 the fiber surfaces, and then, as shown in FIG. 4, a part of the overlapping portion 12 is pressed with a predetermined pressing force to form a pressed portion P1, and 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, and 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 surface) of the two sheets 2 and 3 is imaged with an electron microscope. The shape and size of the region P2 in a plan view are not particularly limited, but it can be, for example, a rectangular shape in a plan view with a short side length of 5 mm and a long side length of 10 mm. The drawing substitute photograph in FIG. 3 was imaged using a scanning electron microscope ("JSM-6510" manufactured by JEOL Ltd.). 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 Fig. 3(a) and the subject in Fig. 3(b) have different pressing forces applied to the overlapping portion 12 in the process of forming the pressed portion P1, with the pressing force of the subject in Fig. 3(a) being 10 MPa and the pressing force of the subject in Fig. 3(b) being 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 Fig. 3(a), there are portions where the sheets 2 and 3 are in close contact with each other via their fiber surfaces, whereas in Fig. 3(b), there are substantially no portions where the sheets 2 and 3 are in close contact with each other and a relatively large gap (black portion) 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 laminate 11 in the contact portion forming process, the pressing force applied to the overlapping portion 12 is insufficient to be the nip pressure (less than 1 MPa) 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 the nip pressure (for example, 1 MPa or more).

[0039] In the contact portion forming step, the sheet laminate 11 may simply be pressed, but the 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). This makes it possible to easily and reliably form the contact portion 13. The term "easily form the contact portion 13" used here means that the contact portion 13 can be formed at a lower surface pressure or in a shorter time by pressing while heating it, compared to pressing without heating. According to the findings of the present inventors, for example, when the sheets constituting the sheet laminate are spunbonded nonwoven fabrics or air-through nonwoven fabrics, it is difficult to form a contact portion in which the fiber surfaces of the sheets are peelably adhered to each other by simply pressing the sheet laminate. Therefore, when such a nonwoven fabric is used as the raw material of the sheet fusion body, it is preferable to press the sheet laminate while heating it at a temperature below the melting point of the thermoplastic resin forming the nonwoven fabric in the contact portion forming step. 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 press the sheet laminate 11 while heating it 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 process may be appropriately adjusted 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 sheet is typically the same as the heating set temperature of 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, the sheet laminate 11 having the contact portion 13 formed therein is then placed 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 to form a seal 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 toward 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 a laser beam, a part of the material (such as a thermoplastic resin) of the irradiated portion of the laser beam is heated, vaporized, and disappears, so that the irradiated portion is cut (melted), and the cut edge of the sheets 2 and 3 is generated, and the cut edge is heated by the laser beam to form a fused portion 5M in the vicinity of the irradiated portion. In this way, the cut edge portions of the sheets 2 and 3 are joined to each other by the fused portion 5M to form a sealed edge portion 5. At this time, as described above, the vicinity of the irradiated portion of the laser beam is melted by being heated by the laser beam, and the melted material permeates a relatively wide range from the irradiated portion through the fibers of the contact portion 13, so that the fusion of the cut edge portions of the sheets 2 and 3 in the sealed edge portion 5 is strong. The laser light irradiation process is a process in which the workpiece (sheet laminate 11) is cut (melted) 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 a 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 contour of the glove 1, which is the object of manufacture, is formed in the sheet laminate 11, and the other portion of the contour of the glove 1 is not irradiated with laser beam. Therefore, after the laser beam irradiation step and before the next continuum cutting step, neither the glove 1 nor the unnecessary portion 9 is cut off from the sheet laminate 11.

[0045] In this embodiment, the sheet laminate 11, which is the workpiece, is a continuous body in which multiple gloves 1 (fused sheets) or intermediate products thereof are connected in one direction MD, so 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 belt-like sheet laminate 11 having the sealed edge portion 5 formed and passing through the laser light irradiation section 40 is introduced into the cutting section 50, and cut into the length of one unit of product by the cutter roll 51 to produce multiple individual gloves 1 continuously. In FIG. 2, the linear cutting line 8 extending in the CD indicates the portion cut by the blade 51a of the cutter roll 51. By cutting the sheet laminate 11 along the cutting line 8, the sheet laminate 11 is cut into gloves 1 or intermediate products (products) and unnecessary parts 9 (non-products), which are the other parts. The gloves 1 or intermediate products are transported to the next process such as a packaging process by the transport means 54, and the unnecessary parts 9 are collected by a separate route. The method for recovering the unnecessary portion 9 may be any method for recovering the unnecessary portion generated by cutting the workpiece, which has been conventionally adopted in this type of production line. The method for producing a fused sheet body of the present invention may include a step of recovering such unnecessary portion. 2, in this embodiment, the cutting line 8 is not continuous over the entire CD length of the sheet laminate 11, i.e., 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, configurations different from the above embodiment will be mainly described, and configurations similar to the above embodiment will be assigned the same reference numerals as in the above embodiment and description will be omitted. For 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 subjected to intermittent pressing to form the adhesion portion 13 in the sheet laminate 11, but in the present invention, the method of performing the adhesion portion forming step (the method of pressing the sheet laminate) is not particularly limited, and may be, for example, a continuous pressing method. Fig. 6 shows the main part of a manufacturing apparatus 10A that performs the adhesion portion forming step by the continuous pressing method.

[0048] The manufacturing apparatus 10A is different from the manufacturing apparatus 10 having the intermittent pressing means 31 as the contact portion forming unit 30 in that the manufacturing apparatus 10A has the continuous pressing means 35 as the contact portion forming unit 30. The manufacturing apparatus 10A is also different from the manufacturing apparatus 10 having the dedicated equipment for performing the sheet stacking process, such as the sheet laminate forming unit 20. In the manufacturing apparatus 10A, the contact portion forming unit 30 (continuous pressing means 35) performs the sheet stacking process and the contact portion forming process. The continuous pressing means 35 includes a sheet supplying means 34 and a pair of pressing rolls 36, 37. The sheet supplying means 34 is configured similarly to the sheet supplying means 21 included in the manufacturing apparatus 10. The pressing rolls 36, 37 each have a pressing surface that contacts the workpiece that is a circumferential surface (curved surface), which differs from the pressing tools 32, 33, which have a flat pressing surface. The pressing rolls 36, 37 are disposed on both sides (upper and lower in the illustrated embodiment) of the sheet stack 11, which is the workpiece, and are disposed so that their pressing surfaces are constantly in contact with the sheet stack 11 being transported.

[0049] In the manufacturing apparatus 10A, as shown in Fig. 6, the sheets 2 and 3 are continuously fed from the raw rolls 2R and 3R, and the fed sheets 2 and 3 are introduced into a gap (nip portion) of a pair of pressing rolls 36 and 37 while being joined 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). In addition, in the manufacturing apparatus 10A, the sheet laminate 11 is continuously conveyed, and in the portion of the continuous belt-like sheet laminate 11 that has passed through the continuous pressing means 35, the contact portion 13 is formed over the entire length of the MD of the 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 effect 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 for the glove 1 using the manufacturing apparatus 10, in the contact part forming step, the contact part 13 is formed on the entire sheet laminate 11 having the overlapping part 12 between the fiber surfaces (see FIG. 2). However, as shown in FIG. 7, in the contact part forming step, the contact part 13 may be partially formed on the sheet laminate 11. That is, the sheet laminate 11 which has undergone the contact part forming step may have the contact part 13 and the non-formed part of the contact part 13, i.e., the overlapping part 12, mixed therein. In the manufacturing method for the glove 1 using the manufacturing apparatus 10B, in the contact part forming step, the contact part 13 is intermittently formed on the sheet laminate 11 in the MD, and in the sheet laminate 11 which has undergone the contact part forming step, the contact part 13 and the overlapping part 12 which is the non-formed part of the contact part 13 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 numeral 14 straddles both the 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 contact portion 13 and the overlapping portion 12. As a result, the irradiated portion 14 of the 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 a non-pressurized state, and the cut edges of the sheets 2 and 3 generated by the irradiation of the laser beam 41L are not fused to each other, so that 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 the 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 melting and fusing of the irradiated portion of the laser light by irradiating the contact portion 13 with the laser light differs from the energy required to achieve melting of the irradiated portion of the laser light by irradiating the overlapping portion 12 (non-contact portion) with the laser light, the fused sheet body can be manufactured more efficiently by selecting the irradiation conditions of the laser light according to the purpose.

[0052] Moreover, the manufacturing apparatus 10B does not include a cutting section 50, and in the manufacturing method of the glove 1 using the manufacturing apparatus 10B, in the laser light irradiation process, the sheet laminate 11 (a continuous body in which a plurality of fused sheets or intermediate products thereof are connected in one direction MD) is cut by irradiation with a laser light to manufacture a single glove 1 (fused sheet body) (continuous body cutting process). Specifically, the sheet laminate 11 is irradiated with a laser light 41L in the laser light irradiation section 40 to form a seal edge portion 5 and an opening 7 corresponding to the entire contour of the glove 1 to be manufactured, thereby cutting the continuous belt-like sheet laminate 11 into a plurality of single gloves 1 and the remaining unnecessary portion 9. The single gloves 1 manufactured in this manner are transported to the next process such as a packaging process by the transport means 42, and the unnecessary portion 9 is collected by a separate route.

[0053] The fused sheet produced by the present invention can be used for various purposes, such as finger cots, socks, hats, joint supports, etc. in addition to the gloves mentioned above.

[0054] While the present invention has been described based on the preferred embodiment, the present invention is not limited to the above embodiment and can be modified as appropriate without departing from the spirit of the present invention. For example, in the above embodiment, a continuous belt-like 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 individual sheet fusion product to be manufactured may also be used. In the above embodiment, the number of layers of sheets in the sheet laminate is two, but the number of layers may be three or more. In this case, the sheet laminate has a plurality of overlapping portions (number of layers minus 1) between two sheets adjacent in the thickness direction, which are intermittently arranged in the thickness direction, and at least one of the overlapping portions is an overlapping portion between fiber faces.

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

[0056] 1 Gloves (sheet fused) 2,3 seats 4 Laminated structure 5 Sealing edge 10,10A,10B manufacturing equipment 11 Sheet stack 12 Overlapped area of ​​fiber surfaces (non-contact area) 13 Contact area 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 the steps of: forming a laminated structure of a plurality of sheets; and forming a sealed edge portion at an edge portion of the laminated structure where edges of the plurality of sheets are fused to each other; and at least one surface of each of the plurality of sheets is a fiber surface formed of fibers containing a thermoplastic resin, the method comprising the steps of: a sheet stacking step of stacking the plurality of sheets to form a sheet stack having overlapping portions between the fiber surfaces; a contact portion forming step of forming a contact portion in the sheet laminate where the plurality of sheets are releasably adhered to each other; a laser beam irradiation step of irradiating the sheet laminate in which the adhesive portion is formed with a laser beam in a desired pattern with the sheet laminate in a non-pressurized state, thereby melting the sheet laminate and fusing together the cut edges of the plurality of sheets produced by the melting, thereby forming a seal edge portion in the sheet laminate at the portion irradiated with the laser beam; A method for producing a fused sheet comprising the steps of:

2. The method for producing a fused sheet body according to claim 1 , wherein in the contact portion forming step, the sheet laminate is pressed to form the contact portion.

3. The method for producing a fused sheet body according to claim 2 , wherein in the contact portion forming step, the sheet laminate is pressed while being heated at a temperature equal to or lower than a melting point of the thermoplastic resin, thereby forming the contact portion.

4. The method for producing a fused sheet body according to claim 2 , wherein in the contact portion forming step, the sheet laminate is pressed while ultrasonic waves are applied thereto to form the contact portion.

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 the fused sheet body in individual pieces.

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 according to any one of claims 1 to 6, wherein the average fiber diameter of the constituent fibers of the fiber surface is 0.3 to 3 µm.

8. In the contact portion forming step, the contact portion is partially formed in the sheet laminate, The method for producing a sheet fusion body according to any one of claims 1 to 7, wherein in the laser light irradiation step, the laser light is irradiated so that the irradiated portion of the laser light spans both the contact portion and a non-contact portion of the contact portion.

Images