JP2011126011A - Method of manufacturing sheet fused material and laser type joining device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a sheet fused material which can press and adhere continuously sheets to be fused to each other in fusing sheets of a sheet laminate by using a laser beam while carrying the sheet laminate and prevents or reduces the hardening of surfaces of the sheet fused material. <P>SOLUTION: The method of manufacturing the sheet fused material comprises steps for pressing and carrying a sheet laminate 3 composed of a plurality of sheets 31 and 32 having transmissivity to a laser beam between a hollow rotating roll 2 having a laser beam transmissive portion transmitting the laser beam on the peripheral surface and a heating surface 42 absorbing the laser beam and generating heat and irradiating the heating surface 42 which moves in contact with the sheet laminate 3 to be carried with the laser beam 51 from the inside of the rotating roll 2 so as to fuse the sheets 31 and 32 in the sheet laminate 3 through heat transfer from the heating surface 42 generating heat by the irradiation of the laser beam. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a sheet fusion body and a laser-type bonding apparatus.

  Conventionally, in the manufacture of sanitary articles such as disposable diapers and sanitary napkins, a heat roll apparatus has been widely used for joining stacked sheets. In a general heat roll apparatus, between a pattern roll having a convex portion of a predetermined shape on the peripheral surface and a smooth anvil roll, a plurality of superposed sheets are integrally pressed and heated, A fused portion having a shape corresponding to the shape of the convex portion is formed.

  In addition, a method of fusing sheets together using a laser beam is known. For example, although it is not a technique related to the manufacture of sanitary products, Patent Document 1 discloses a plurality of sheets introduced between a first roller made of a material that transmits a laser beam and a second roller made of a material whose surface easily deforms. A technique is described in which a laser beam is irradiated from the inside of the first roller to the sheets, and the sheets are fused together. Further, in Patent Document 2, as a method for joining resin films, first and second resin films having laser transparency are laminated and disposed, and both resin films in that state are irradiated with a laser beam from one side. And the technique which heats the laser absorption board arrange | positioned on the other side and welds both resin films with the conduction heat is described.

JP 2004-001507 A JP 2004-050513 A

  The fusing method using pattern rolls requires replacement of the pattern roll when changing the formation pattern of the fused part, and can flexibly respond to changes in product specifications and fused part patterns. Can not.

In the technology of Patent Document 1, the upper material that is transparent to the laser beam and the lower material that is impermeable to the laser beam are overlapped, and the laser beam is irradiated from the upper material side, and both materials are melted at the contact surface of each other. This is a technique for joining them together. Therefore, when it is desired to fuse materials that are transmissive to the laser beam, it is necessary to blend an absorbent material or the like that absorbs the laser beam into one of the materials. However, the blending of the absorbent material and the like has a problem of increasing the cost and changing the physical properties of the sheet.
Nonwoven sheets often used in sanitary products are aggregates of fibers, and the basis weight often has a fluctuation of about ± 10%. For this reason, when the nonwoven fabric sheet is absorbed and heated, even if the laser is irradiated with a constant intensity, it is difficult to control the temperature, and thus unevenness in bonding strength and the like is likely to occur.

  The technique of Patent Document 2 does not require coloring of the resin film, but does not assume a case where the belt-like sheets are joined while being continuously conveyed as in the manufacture of sanitary goods.

The present invention can efficiently fuse a plurality of sheets having laser beam transparency, and can stably perform the fusion while conveying the sheet. About.
Further, the present invention can efficiently fuse a plurality of sheets to be fused to each other, even if all of them have high laser light transmission properties. The present invention relates to a method for manufacturing a sheet fusion body and a laser-type bonding apparatus that can be stably performed while being conveyed.

  The present invention provides a sheet laminated body in which a plurality of sheets having laser beam permeability are stacked, a hollow rotating roll having a laser beam transmitting part that transmits the laser beam to a peripheral surface, and the laser beam. The laser beam is radiated from the inside of the rotating roll to the heat generating surface that is conveyed while being pressed between the heat generating surface that absorbs and generates heat, and moves while being in contact with the sheet laminate being conveyed, The present invention provides a method for producing a sheet fusion body, in which sheets in the sheet laminate are fused together by heat transfer from a heat generating portion on the heat generation surface that has generated heat by light irradiation.

  In addition, the present invention provides a hollow rotating roll, which is a laser light transmitting portion that transmits a laser beam entirely or partially, and a sheet laminate in which a plurality of sheets are stacked. A pressure device including a pressure belt that can be pressed against a surface and a laser irradiation mechanism that irradiates a laser beam from the inside to the outside of the rotating roll, and the sheet in the pressure belt The present invention provides a laser-type bonding apparatus in which a surface to be brought into contact with a laminated body is a heat generating surface that has an absorption heat generation property with respect to the laser light.

  Furthermore, this invention provides the manufacturing method of an absorbent article including the process of manufacturing a sheet fusion body with the manufacturing method of the said sheet fusion body or the said laser-type joining apparatus.

According to the method for producing a sheet fusion body of the present invention, a plurality of sheets having laser light permeability can be efficiently fused, and the fusion is stably performed while the sheets are conveyed. be able to.
According to the laser-type bonding apparatus of the present invention, even if a plurality of sheets to be fused to each other are all highly laser-transmissive, they can be efficiently fused, Fusion can be stably performed while conveying the sheet.

FIG. 1 is a diagram illustrating a laser-type bonding apparatus according to the first embodiment and a state in which a sheet fusion body is manufactured using the laser-type bonding apparatus. FIG. 2 is an explanatory view showing a state in which a fused portion is formed in the sheet laminate using the laser type bonding apparatus of FIG. FIG. 3 is a plan view showing a partially fused sheet fusion body manufactured in the first embodiment. FIG. 4 is an explanatory diagram for explaining a formation pattern and a formation method of the fusion part in the first embodiment. FIG. 5 is a cross-sectional view of the vicinity of the outer peripheral surface of the rotating roll showing how the sheets in the sheet laminate are fused together by heat transfer from the heat generating portion on the heat generating surface that has generated heat by irradiation with laser light. FIG. 6 is a diagram illustrating a laser-type bonding apparatus according to the second embodiment and a state in which a sheet fusion body is manufactured using the same. FIG. 7 is a view of the rotating roll of the laser-type bonding apparatus of FIG. 6 as viewed from the direction facing the laser transmitting portion. FIG. 8 shows the laser irradiation point, the sheet laminate conveyance speed, and the laser when the laser irradiation point is not moved in the sheet laminate conveyance direction (MD) when forming the fused portions 75, 76, 77 of FIG. It is a graph which shows the time change of the sheet laminated body conveyance direction (MD) movement speed of an irradiation point. FIG. 9 shows the laser irradiation point and the sheet laminate conveyance direction (MD) when the laser irradiation point is not moved in the sheet laminate conveyance direction (MD) when forming the fused portions 75, 76, and 77 in FIG. Is a graph showing a change over time of the moving speed of the laser irradiation point in the direction (CD) perpendicular to the sheet stack conveyance direction (MD) of the laser irradiation point. FIG. 10 shows the relative speed between the sheet laminate and the laser irradiation point when the laser irradiation point is not moved in the sheet laminate conveyance direction (MD) when forming the fused portions 75, 76, and 77 in FIG. It is a graph which shows a time change. FIG. 11 shows the laser irradiation point, the sheet laminate conveyance speed when the laser irradiation point is moved in the sheet laminate conveyance direction (MD) when forming the fused portions 75, 76, 77 of FIG. It is a graph which shows the time change of the sheet | seat laminated body conveyance direction (MD) moving speed of a laser irradiation point. FIG. 12 shows the laser irradiation point and the sheet laminate conveyance direction (when the laser irradiation point is moved in the sheet laminate conveyance direction (MD) when forming the fused portions 75, 76, and 77 in FIG. It is a graph which shows the time change of the moving speed of the laser irradiation point of the direction (CD) orthogonal to the sheet laminated body conveyance direction (MD) of the sheet laminated body of MD) sheet laminated body and a laser irradiation point, and a laser irradiation point. FIG. 13 shows the laser irradiation point, the sheet laminate, and the laser irradiation when the laser irradiation point is moved in the sheet laminate conveying direction (MD) when forming the fused portions 75, 76, 77 of FIG. It is a graph which shows the time change of the relative velocity of a point.

Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings.
First, a first embodiment of the present invention will be described.
As shown in FIG. 1, the laser-type bonding apparatus 1 according to the first embodiment includes a hollow rotating roll 2 and a plurality of sheets 31 and 32 that are made of a material that is transparent to laser light. A belt-type pressurizing device 4 (pressurizing device) having a pressurizing belt 41 capable of pressurizing the sheet laminate 3 having the structure described above against the circumferential surface of the rotary roll 2 and from the inside to the outside of the rotary roll 2. A laser irradiation mechanism 5 that irradiates laser light 51 toward the head, a temperature control device 6 that controls the temperature of the pressure belt 41, and a preheating device 8 that preheats the sheet laminate 3 before being fused are provided.

The rotating roll 2 according to the first embodiment is a laser light transmitting portion whose entire peripheral surface is made of a laser light transmitting material.
The rotary roll 2 is fixed to the center of the side surface of the rotary roll 2 at the back in FIG. 1, and a shaft extending in the direction of the rotary shaft is supported by a bearing or the like on the outer side of the rotary roll 2, and the shaft is rotated by a motor. Thus, it is rotationally driven in the direction of arrow A in the figure. The conveyance speed of the sheet laminate 3 is the same as the rotation speed (circumferential speed) of the rotary roll 2.

  A rotary position detector (not shown) such as a rotary encoder is installed on the shaft of the rotary roll 2 and always measures the rotational position of the rotary roll 2. Further, the rotating roll 2 stores heat by heat generation for sheet fusion, but the cooling may be left to natural heat dissipation by the rotation of the rotating roll 2, or a forced cooling mechanism such as air cooling or water cooling may be provided. good. Further, a cooling roll in contact with the rotating roll 2 may be provided.

The pressure belt 41 of the belt-type pressure device 4 moves the sheet laminated body 3 supplied on the rotary roll 2 by an upstream conveyance mechanism (not shown) from the outer side in the diameter direction of the rotary roll 2 toward the rotational axis. The sheet laminate 3 is pressed against the peripheral surface of the rotary roll 2. More specifically, as shown in FIG. 1, the circumferential surface from the upper end of the rotating roll 2 to the side of the downstream side in the conveying direction of the sheet laminate 3 is configured to be in pressure contact with the sheet laminate 3.
The angle range in which the sheet laminated body 3 is pressed against the peripheral surface of the rotary roll 2 by the pressure belt 41 is 45 degrees or more when 360 ° is set for press contact over the entire circumference of the rotary roll 2. It is preferable that it is 45 to 180 degrees, more preferably 60 to 120 degrees.

  The belt-type pressure device 4 includes a pressure belt 41 and three rolls 43a, 43b, and 43c that rotate in a state where the pressure belt 41 is bridged. The pressure belt 41 rotates by being in contact with the sheet laminate 3 continuously conveyed in one direction by the rotating roll 2. Any of the rolls 43 a, 43 b, 43 c provided in the belt type pressurizing device 4 can be driven to rotate at the same peripheral speed as that of the rotary roll 2.

The surface of the pressure belt 41 that is brought into contact with the sheet laminate 3 is a heat generating surface 42 that absorbs heat from the laser light 51 irradiated by the laser irradiation mechanism 5.
Whether or not the sheets 31 and 32 to be fused to each other have laser beam permeability, and whether or not the rotary roll 2 has a laser beam transmitting portion is brought into contact with the sheet laminate 3 of the pressure belt 41. Whether or not the surface has absorption heat generation depends on the relationship with the wavelength of the laser beam used.

Examples of the laser used in the present invention include YAG laser, LD laser (semiconductor laser), YVO ₄ laser, and fiber laser.
The plurality of sheets to be fused to each other are those through which the laser passes in relation to the laser used, and more preferably have high laser transparency.

When fusing sheets of synthetic resin non-woven fabrics and films, which are widely used in the manufacture of sanitary products such as disposable diapers and sanitary napkins, using the method and apparatus of the present invention, YAG lasers and LD lasers are used as lasers. (Semiconductor laser), YVO ₄ laser, fiber laser, etc., the wavelength in the near infrared region (0.7 to 2.5 μm) is preferably used, and the wavelength of 0.8 to 1.2 μm is more preferable. In these wavelength bands, the permeability to sheets made of polypropylene (PP) or polyethylene terephthalate (PET) is relatively high.

In addition, examples of the pressure belt whose surface to be brought into contact with the sheet laminated body absorbs heat with respect to the laser include (1) a belt base material made of a heat resistant material such as glass cloth or aramid cloth, and a heat resistant resin. Absorbing (fluorine resin, etc.) and heat-resistant resin belt (fluorine resin belt) obtained by baking it, and further heat-absorbing resin impregnated with laser light absorption of carbon, coloring materials, near infrared absorbers, etc. Heat-resistant resin belt with improved heat absorption of laser light by blending materials, (2) Light absorption rate in the near infrared region is relatively high among metals, and thermal conductivity is compared with metals Examples thereof include a metal belt having a thickness of 0.2 mm or less, which is made of a relatively low metal such as titanium or nickel.
The pressure belt 41 is flat on the entire surface to be brought into contact with the sheet 31, or at least the portion irradiated with the laser light on the heat generating surface 42, so that the heat generated by the laser light is efficiently applied to the sheet 31 and the sheet 32. It is preferable from the viewpoint of communicating well.

  In addition, as a material for forming the laser light transmitting portion of the rotary roll 2, a material that transmits the laser light to be used can be used without particular limitation. For example, quartz glass, sapphire, fluorite, etc. are mentioned if it is a wavelength range of 0.8-1.2 micrometers. In particular, quartz glass and sapphire are preferable in view of mechanical characteristics such as hardness and coefficient of thermal expansion.

The laser irradiation mechanism 5 includes a laser generator (not shown) that irradiates laser light 51 in one direction from the irradiation head 50, a carriage 52 that advances and retreats in a direction parallel to the rotation axis of the rotary roll 2, and the carriage The reflection mirror 53 attached to 52 and the position where the laser beam 51 hits the heat generating surface 42 of the pressure belt 41 (irradiation point P) are rotated around the predetermined rotation axis. And a rotating mechanism (not shown) that moves in the direction. The advance / retreat position of the carriage 52 and the rotation position of the reflection mirror 52 are controlled based on the rotation position of the rotary roll 2 by a controller (not shown). Furthermore, the controller controls ON / OFF and output of laser output.
With the laser irradiation mechanism 5 having such a configuration, the position (irradiation point P) where the laser beam 51 hits the heat generating surface 42 of the pressure belt 41 is set in the conveyance direction (MD) of the sheet laminate 3 and the conveyance direction. Can be arbitrarily moved in both directions (CD) orthogonal to the direction. For the movement of the carriage 52, a servo motor, a hydraulic cylinder, a pneumatic cylinder, a hydraulic motor or the like can be used. A servo motor is preferably used to rotate the reflection mirror 53.

Further, the irradiation point P by the laser beam 51 emitted from the irradiation head 50 is moved in the circumferential direction and the axial direction of the rotary roll 2 by using a commercially available galvano scanner such as MIRAMOTION system manufactured by YE Data Co., Ltd. May be controlled. In this case, a three-dimensional control system (having a mechanism capable of controlling the focal length) having a variable focal length is preferable in order to prevent focal blurring on the heat generating surface 42 due to a change in the optical path of the laser light.
Further, the output of the laser beam emitted from the laser generator is such that the relative strength is not changed due to the change in the relative speed, which is the difference between the conveying speed of the sheet laminate 3 and the moving speed of the irradiation point P. It is preferable to be controlled by. The output of the laser beam is controlled almost in proportion to the relative speed. That is, when the relative speed is low, the laser output is decreased, and conversely, when the relative speed is high, the laser output is increased. In this case, it is desirable to use a laser oscillator having an external output control function using an analog signal or the like.

  The temperature control device 6 is capable of controlling at least a surface (heat generation surface) 42 in contact with the sheet laminate 3 in the pressure belt 41 to a predetermined temperature or less. The temperature control device 6 includes a temperature measuring means (not shown) for measuring the temperature of the heat generating surface 42, a cooling means (not shown) for cooling the heat generating surface 42, and a heating means (not shown) for heating the heat generating surface 42. ) When the temperature measured by the temperature measuring means exceeds or exceeds a predetermined value, the cooling means is operated for a predetermined time or until the temperature returns below the predetermined temperature, and the temperature measuring means measures the temperature. When the measured temperature is lower than a predetermined value, a control unit 61 is provided that operates the heating means for a predetermined time or until the temperature reaches a predetermined temperature. The temperature control of the heat generating surface may be performed by distinguishing between the heat generating surface in contact with the sheet laminate 3 of the pressure belt 41 and the surface on the opposite side thereof, and the temperature of the heat generating surface may be controlled. The temperature of the pressure belt 41 may be controlled.

  Various known devices can be used as the temperature measuring means, and a contact type or a non-contact type can be used. As the temperature measuring means, for example, a contact type using a thermocouple is provided on the surface of the roll 43c, or a non-contact type temperature measuring means (such as one using infrared rays) is used as the roll 43c and the roll 43a. Or in the vicinity of the roll 43c or the sheet laminate 3 on the roll 43a.

Various known means can be used as the cooling means. As the cooling means, for example, circulating cooling water (or hot water) may be circulated in the roll 43c or the roll 43a, and the cooling water temperature or flow rate may be controlled, or between the roll 43c and the roll 43a, The roll 43c or the one that blows wind against the pressure belt 41 on the roll 43a can be used.
Various known means can be used as the heating means. As the heating means, for example, a heater is placed inside the roll 43c or the roll 43a, hot air or far infrared rays are applied to the pressure belt 41 between the roll 43c or the roll 43a, or between the roll 43c or the roll 43a. May be.

  The preheating device 8 heats the sheet laminate 3 to a predetermined temperature before irradiating the sheet laminate 3 with laser light and fusing it. The preheating device 8 includes heating means 81 that heats the sheet laminate 3 by applying hot air, far-infrared rays, a heated roll or the like to the sheet laminate 3 before being introduced onto the rotary roll 2, and the heated sheet laminate 3. A preheating temperature measuring means (not shown) for measuring the temperature, and a controller for controlling the output (degree of heating) of the heating means 81 so that the temperature measured by the preheating temperature measuring means is within a predetermined range. 82. As the heating means 81, a heating box provided with an inlet and an outlet for the sheet laminate 3 and having a heater therein, a heating roll incorporating a heater, and rotating in contact with the sheet laminate 3 is provided. It can also be used.

FIG. 2 shows a state in which the fused portion 7a along the contour of the sanitary napkin is formed on the sheet laminate 3 using the laser-type bonding apparatus 1 described above. The rotational speed (circumferential speed) of the rotary roll 2 and the conveyance speed of the sheet laminate 3 are the same.
The laser-type bonding apparatus 1 described above includes a pair of laser irradiation mechanisms 5 having the above-described configuration. As shown in FIG. 3, one laser irradiation mechanism makes a boundary a straight line 72 passing through the center in the width direction of the napkin. The fused portion 7a on one side is formed, and the fused portion 7b on the other side is formed with the straight line 72 as a boundary by the other laser irradiation mechanism. One fused portion 7a and the other fused portion 7b have a line-symmetric shape with respect to the straight line 72, and the method of moving the irradiation point P of each of the pair of laser irradiation mechanisms is the straight line 72. This is the same except that the laser beam 51 is emitted from a position that is line-symmetric with respect to the line and the carriage 52 and the reflection mirror 53 are moved to be line-symmetric with respect to the straight line 72.

FIGS. 2 and 4 show how the fused portion 7a is formed along the half outline of the sanitary napkin and how it is formed.
In the method of the first embodiment, the fusion part including the component in the direction CD orthogonal to the conveyance direction MD of the sheet laminate 3 is formed by rotating the laser beam irradiation point P at the predetermined rotation of the reflection mirror 53. By rotating about the axis, the surface of the rotating roll 2 is moved in the conveying direction MD and moved in the direction CD perpendicular to the conveying direction, and the sheet laminate 3 and the laser beam in the conveying direction MD are moved. This is performed while slowing the relative speed with the irradiation point P. For example, as shown in FIG. 4, the fusion part 7 a described above, the fusion part 7 a, and its tangent line is 45 degrees with respect to both the conveyance direction MD of the sheet laminate 3 and its orthogonal direction CD. , The fusion parts 73, 75, 77 and 79 are all orthogonal to the conveyance direction from the component b in the conveyance direction MD of the sheet laminate 3 when divided into the fusion parts 73 to 79. The component a in the direction CD is large. While forming these fused parts 73, 75, 77 and 79, the irradiation point P of the laser beam 51 is moved in the rotation direction of the rotary roll 2 as shown by an arrow B in FIG. If it is not moved, the moving speed of the carriage 52, which is very large depending on the shape of the fused part, for example, must be infinite when the fused part is formed in a direction perpendicular to the conveying direction, is mechanically realized. It can be reduced to the speed possible. In addition, this makes it possible to take a long time to form the fused portions 73, 75, 77, and 79 with laser light, so that even if the output of the laser oscillator is insufficient, the necessary sheets can be fused together. It is also possible to reduce the relative speed to a speed at which strength can be obtained. Furthermore, since the required maximum output power of the laser beam can be reduced by lowering the relative speed, the laser oscillator can be reduced in capacity, the apparatus can be saved in space, and the cost can be reduced. In addition, it is possible to reduce the variation in the fusion strength at each fusion site together with the control of the laser light output by the relative speed.

  In addition, while forming the fusion | melting part 74,76,78 in FIG. 4, the irradiation point P of a laser beam is moved to the reverse direction (counter-rotation direction of the rotating roll 2) with respect to this conveyance direction MD, It is preferable to cancel the movement amount of the irradiation point P during the formation of the fused parts 73, 75, 77. In addition, after the formation of the fusion part 79 and before the formation of the fusion part 73, the irradiation of the laser beam is temporarily stopped, and the irradiation point P of the laser light is moved in the conveyance direction MD or the opposite direction, thereby fusing. It is preferable to cancel the movement amount of the irradiation point P during the formation of the portion 79. In FIG. 1, a state where the irradiation point P of the laser beam 51 is moved from the initial position P1 to P2 is indicated by a dotted line, but this movement distance can be appropriately set according to the planar view shape of the fused portion. .

Here, regarding the control of the irradiation point P, the control of the movement of the irradiation point P of the laser beam when fusing the fusion parts 75, 76, 77 of the fusion part 7a is taken as an example, and FIGS. This will be described more specifically with reference to FIG.
FIGS. 8 to 10 show an example of how to move the irradiation point of the laser beam. When the formation pattern of the fusion part shown in FIGS. 3 shows a change in the relative speed between the sheet laminate 3 and the laser irradiation point P over time when the laser irradiation point P at which the laser is applied to 3 is moved only in the direction CD perpendicular to the conveyance direction MD of the sheet laminate 3. . 11 to 13 show another example of how to move the laser light irradiation point. The laser irradiation point P is moved in both the conveyance direction MD of the sheet laminate 3 and the direction CD perpendicular thereto. The change of the relative velocity of the sheet | seat laminated body 3 and the laser irradiation point P in the time passage at the time of making it show is shown.
The horizontal axis of FIGS. 8 to 13 represents the passage of time, and the left vertical axis represents the position PCD of the irradiation point P in the CD direction. The right vertical axis represents the conveyance speed VL of the sheet laminate 3, the MD direction movement speed Vy of the irradiation point P, the movement speed Vx of the irradiation point P in the CD direction, and the relative speed Vy of the sheet stack 3 and the irradiation point P in the MD direction. ', Each speed of the relative speed V between the sheet laminate 3 and the irradiation point P is shown.

ＶＬ、Ｖｙ、Ｖｙ’についてはシート搬送方向が＋でその反対方向が−となる。 Ｖｘは図４の下方向（図１だと手前方向）が−、図４上方向（図１では奥方向）が＋である。 The relative speed V between the sheet laminate 3 and the irradiation point P is a combined speed of the MD direction relative speed Vy ′ of the sheet stack 3 and the irradiation point P and the CD direction moving speed Vx of the irradiation point P, and is obtained by the following method. .
(Calculation method of relative speed V)
The conveyance speed of the sheet laminate 3 is VL (MD direction), and the speed at which the irradiation point P is moved in the MD direction is Vy. Let Vx be the moving speed of the irradiation point P in the CD direction. The relative speed Vy ′ in the MD direction between the sheet laminate 3 and the irradiation point P is a difference between the conveyance speed VL of the sheet laminate 3 and the MD moving speed Vy of the irradiation point P. The movement speed Vx in the CD direction of the irradiation point P is obtained from the change per time of the position of the irradiation point P in the CD direction. 8 to 10, since the sheet laminate 3 is not conveyed in the CD direction, the CD direction component of the relative velocity between the sheet laminate 3 and the irradiation point P is the CD direction moving speed Vx of the irradiation point P is: equal. The relative velocity V between the sheet laminate 3 and the irradiation point P is obtained by the following formula (1) from the relative velocity Vy ′ in the MD direction between the sheet laminate 3 and the irradiation point P and the moving velocity Vx in the CD direction of the irradiation point P. .

For VL, Vy, and Vy ′, the sheet conveyance direction is + and the opposite direction is −. Vx is − in the downward direction in FIG. 4 (frontward in FIG. 1) and + in the upward direction in FIG. 4 (backward direction in FIG. 1).

  8 to 10 show speeds when the irradiation point P is not moved in the MD direction and the position PCD of the irradiation point P in the CD direction. FIG. 8 shows changes over time of the position PCD of the irradiation point P in the CD direction, the conveyance speed VL of the sheet laminate 3, and the movement direction Vy of the irradiation point P in the MD direction. FIG. 9 shows changes over time of the position PCD of the irradiation point P in the CD direction, the moving speed Vx of the irradiation point P in the CD direction, and the relative speed Vy ′ of the sheet stack 3 and the irradiation point P in the MD direction. Has been. FIG. 10 shows changes in the position PCD of the irradiation point P in the CD direction and the relative speed V between the sheet laminate 3 and the irradiation point P over time. In FIGS. 9 and 10, the display of the fused portions 75, 76, and 77 is omitted.

As shown in FIG. 8, since the conveyance speed VL of the sheet laminate 3 has a constant value, the irradiation point P is not moved in the MD direction (Vy = 0). The MD direction relative speed Vy ′ between the body 3 and the irradiation point P is equal to the conveyance speed VL of the sheet laminate. FIG. 9 is created by processing FIG. 8 based on the relational expression (relative speed Vy ′ = conveying speed VL−Vy).
Further, the moving speed Vx of the irradiation point P in the CD direction is obtained by time differentiation of the position PCD of the irradiation point P in the CD direction, and as shown in FIG. 9, the fusion part having a large component in the CD direction orthogonal to the MD direction. 75 and 77 vary greatly within the time range for fusing.
FIG. 10 shows the relative speed V between the sheet laminate 3 and the irradiation point P, which is a composite speed of the sheet laminate 3 and the MD direction relative speed Vy ′ of the irradiation point P and the CD direction moving speed Vx of the irradiation point P. The relative speed V changes from the conveyance speed VL of the sheet laminate 3 to a speed greater than the maximum value of the CD direction moving speed Vx of the irradiation point P.

  When the sheet conveyance speed is relatively low, in the forms of FIGS. 8 to 10, the irradiation point P is not moved in the sheet laminate conveyance direction, so that it is not necessary to control the rotation of the reflection mirror 53, and simple control is performed. Sheets can be fused in a desired shape.

  On the other hand, FIGS. 11 to 13 show the respective speeds and the CD direction position PCD of the irradiation point P when the irradiation point P is moved in the MD direction. FIG. 11 shows changes over time of the position PCD of the irradiation point P in the CD direction, the conveyance speed VL of the sheet laminate 3, and the movement direction Vy of the irradiation point P in the MD direction. FIG. 12 shows changes over time of the position PCD of the irradiation point P in the CD direction, the moving speed Vx of the irradiation point P in the CD direction, and the relative speed Vy ′ of the sheet laminate 3 and the irradiation point P in the MD direction. Has been. FIG. 13 shows changes in the position PCD of the irradiation point P in the CD direction and the relative speed V between the sheet laminate 3 and the irradiation point P over time. In FIGS. 12 and 13, the display of the fused portions 75, 76, and 77 is omitted.

  As shown in FIG. 11, in the portions corresponding to the fused portions 75 and 77, the irradiation point P is moved to the + side (MD direction), thereby extending the time for forming these fused portions with laser light. . On the other hand, in the portion corresponding to the fusion part 76, the amount of movement in the MD direction at the time of fusion of the fusion part 75 is canceled by moving the irradiation point P to the negative side (anti-MD direction). Further, the amount of movement in the MD direction that occurs when the fused portion 77 is fused can be canceled at the same time as the fusion of the fused portion 77 is completed. It is also possible to return it. FIG. 12 shows the MD direction relative speed Vy ′ and the CD direction movement speed Vx between the sheet laminate 3 and the irradiation point P at this time, and FIG. 13 shows the relative speed V between the sheet laminate 3 and the irradiation point P. As is clear from comparison of these figures, the relative speed between the sheet laminate 3 and the irradiation point P can be reduced by moving the irradiation point P in the MD direction.

  Even in the case where the sheet conveyance speed is relatively high, in the forms of FIGS. 11 to 13, by moving the laser irradiation point in the sheet stack conveyance direction of the irradiation point P, the carriage 52 moves in the CD direction. The advance / retreat speed can be lowered, the degree of compatibility with various fusion patterns other than this example can be increased, and the relative speed between the laser irradiation point and the sheet laminate can be lowered, so the laser output required for fusion can be lowered. it can.

  According to the laser-type bonding apparatus 1 of the first embodiment and the method of manufacturing the sheet fusion body 7 using the same, the sheet laminate 3 is pressed against the outer peripheral surface of the rotary roll 2 by the pressure belt 41 and pressurized. Thus, the sheets 31 and 32 in the laminate 3 can be brought into close contact with each other while the sheet laminate 3 is being conveyed. At this time, the heat generating surface 42 of the pressure belt 41 is also in close contact with the sheet laminate 3. Then, by irradiating the heat generating surface 42 in this state with the laser beam 51 from the inside of the rotary roll 2, as shown in FIG. 5, the portion irradiated with the laser beam 51 on the heat generating surface 42 is a laser. By absorbing light 51 and generating heat, the heat is transmitted to the sheet laminate 3 that is in close contact with the heating surface 42, whereby the sheets 31 and / or 32 in the sheet laminate 3 are melted and then solidified. The sheets 31 and 32 are fused.

According to the laser-type bonding apparatus 1 of the first embodiment and the method of manufacturing the sheet fusion body 7 using the same, the sheets having transparency to the laser beam are conveyed between them in this way. It can be fused efficiently. Further, it is not necessary to add a laser light absorbing material to the sheet for the purpose of enabling fusion by laser light. Therefore, it is possible to prevent the color and various physical properties of the sheet from being unnecessarily changed and the manufacturing cost of the sheet fusion product from being increased.
Even if one or both of the sheets to be fused is a sheet made of an aggregate of fibers, such as a nonwoven sheet often used for sanitary products, the sheet is fused by heat transfer from the heat generating portion of the heat generating surface. By making it wear, it is possible to suppress unevenness such as bonding strength due to fluctuations in basis weight. Thereby, the joint strength as designed can be stably imparted to the fused portion between the sheets.

In the present invention, the temperature control device 6 can control the surface (heat generating surface) 42 of the pressure belt 41 that contacts the sheet laminate 3 to a temperature lower than the melting point of the sheet in the sheet laminate 3. It is preferable from the viewpoint of keeping constant the quality of the fused portion of the sheet laminate 3 and its periphery. The laser beam irradiation point P on the heat generating surface 42 of the pressure belt 41 rises to 200 to 800 ° C. during fusion. Therefore, as the number of times of joining increases, the temperature of the pressure belt 41 and its heat generating surface 42 increases, and is necessary for fusing at the time of new laser irradiation (when the belt presses a new part of the sheet laminate after irradiation). Excessive heat exceeding the temperature causes damage to the sheet laminate, and there is a hole in the fused portion, resulting in a decrease in the fusion strength, or deterioration of the feel of the non-fused portion of the sheet laminate 3 in contact with the heating surface 42. There are things to do. On the other hand, when the temperature of the pressure belt 41 is extremely lower than the temperature necessary for fusion, the laser output necessary to raise the fusion temperature is increased. Therefore, it is preferable to control the temperature of the pressure belt 41 to be equal to or lower than the melting point of the sheet laminate in order to stabilize the bonding quality and lower the laser output during fusion.
Here, the melting point of the sheet in the sheet laminate is the melting point of the resin having the lowest melting point among the resin materials constituting the plurality of sheets included in the sheet laminate. For example, the melting point of polyethylene is about 125 ° C.
Further, the sheet is a core-sheath type composite fiber having a low melting point component as a sheath part and a high melting point component having a higher melting point than the low melting point component as a core part, and such a low melting point component and a high melting point component are in the longitudinal direction of the surface. In the case of the composite fiber of side-by-side type or the like continuously exposed along each, the melting point of the sheet laminate is the melting point of the low melting point component of the composite fiber.

  The temperature of the surface (heat generating surface) 42 that is brought into contact with the sheet laminate 3 is preferably controlled to a temperature that is 10 to 80 ° C. lower than the melting point of the sheet laminate 3, and is controlled to a temperature that is 30 to 50 ° C. lower than the melting point. More preferably. Moreover, similarly to melting | fusing point, the temperature lower than the softening point of the sheet | seat laminated body selected is preferable. When a sheet | seat laminated body contains several components from which a softening point differs, it is preferable to control to the temperature lower than the softening point of the lowest thing among components. For many resin materials, the actual melting point varies around 10 ° C. due to the mixing of impurities and the variation in composition. Moreover, since there is a sheet | seat whose melting | fusing point and a softening point are not clear, it is preferable that the heat generating surface 42 is controlled to the temperature of 30 to 110 degreeC, and it is more preferable to be controlled to 60 to 80 degreeC.

  Further, if the melting point of the sheet 31 located on the sheet laminate 3 side is lower than that of the sheet 32 located on the rotary roll 2 side, it may be possible to join with a smaller laser output, which is preferable from the viewpoint of efficiency.

In the present invention, the preheating device 8 preheats the sheet laminate 3 to a temperature lower than the melting point of the sheets in the sheet laminate, and heats it to a temperature required for fusion with a smaller laser output. From the viewpoint of efficiency.
Here, the melting point of the sheet in the sheet laminate is the highest melting point among the resin materials constituting the plurality of sheets included in the sheet laminate, as in the temperature control of the heating surface 42 of the pressure belt 41. Low resin material.

  The temperature at which the sheet laminate 3 is preheated before the laser light is irradiated (the surface temperature of the sheet laminate 3 or hot air applied to the sheet laminate 3 and the temperature of the heated roll is measured) is the melting point of the sheet laminate 3. On the other hand, preheating to a temperature lower by 10 to 80 ° C is preferable, and preheating to a temperature lower by 30 to 50 ° C is more preferable.

  Further, the moving speed of the carriage 52 is reduced by moving the irradiation point P of the laser beam in the conveying direction of the sheet laminated body 3, and is substantially parallel to the CD direction like the fused portions 73, 75, 77 and 79. If there is no movement of the irradiation point in the MD direction, such as a form, it is possible to cope with a form in which the moving speed cannot be realized mechanically.

Further, by moving the irradiation point P of the laser beam in the conveying direction, it is possible to take a long time to form the fused portions 73, 75, 77 and 79 with the laser beam, so that sufficient fusion strength between the sheets can be obtained. It is also possible to reduce the relative speed V to a speed at which
Furthermore, since the required maximum output power of the laser beam can be reduced by lowering the relative speed, the laser oscillator can be reduced in capacity, the apparatus can be saved in space, and the cost can be reduced.
In addition, it is possible to reduce the variation in the fusion strength of each fusion site together with the control of the laser light output by the relative speed.
The fusion of the sheets with laser light is preferably performed while moving the irradiation point of the laser light in the conveying direction of the sheet laminate, and in that case, it moves in both the conveying direction and the direction orthogonal to the conveying direction. It is also possible to carry out the process while moving the sheet in the conveying direction, or to move the sheet in the direction perpendicular to the conveying direction.

The sheet laminate 3 in the first embodiment is a belt-like sheet 32 that is a raw sheet of a top sheet that forms a skin contact surface of a sanitary napkin, and a raw sheet of a back sheet that forms a non-skin contact surface. The absorbent body 33 is intermittently disposed between the sheet 31 and the obtained sheet fusion body 7 is cut by any means outside the fusion part 7 to produce a sanitary napkin. Is.
Examples of the sheet contained in the sheet laminate and fused to each other include nonwoven fabrics produced by various manufacturing methods, non-woven fabric fiber webs, fabrics, and laminates of these two or more. One or both of the sheets preferably include fibers made of a thermoplastic resin. Examples of the thermoplastic resin include polyolefin such as polypropylene, polyester such as polyethylene terephthalate, polyamide, and the like, and composite fibers composed of these two or more resins can also be used.
The sheet laminate 3 may be a sheet that does not contain a fusing component such as paper in some of the laminated sheets as long as the fusing component is contained in at least one sheet.

6 and 7 are views showing a second embodiment of the present invention.
In 2nd Embodiment, in the production line which manufactures an underpants type disposable diaper continuously, according to 2nd Embodiment with respect to the diaper continuous body 34 (sheet laminated body) of the structure which this diaper continued in the width direction. The fused portions 35 are formed using the laser-type bonding apparatus 1A. The fusion | bond part 35,35 formed in 2nd Embodiment becomes a side seal part located in the side part of each diaper, after dividing the diaper continuous body 34 into each diaper. The side seal part joins both side edges of the back side part arranged on the wearer's back side and both side edges of the abdomen side part arranged on the abdomen side, and the waist opening part and the pair of leg opening parts are joined. To form.

As shown in FIGS. 6 and 7, the rotating roll 2 </ b> A according to the second embodiment has a small window-like laser light transmitting portion 22 made of a laser light transmitting material formed on a part of the peripheral surface. .
Inside the rotary roll 2A, there are a reflection mirror that rotates around a different rotation axis and moves the irradiation point P of the laser beam in the conveyance direction of the sheet laminate 3 and a reflection mirror that moves in a direction perpendicular to the conveyance direction. The galvano mirror 54 provided with is arranged, and the laser light emitted from the irradiation head 50 is irradiated to the diaper continuous body 34 with the direction controlled by the galvano mirror 54. The laser bonding apparatus 1A is provided with two sets of laser irradiation mechanisms having such a configuration, and each laser irradiation mechanism irradiates a diaper connection part of the diaper continuous body 34 with laser light, thereby connecting the diapers. Two linear fused portions (side seal portions) 35, 35 are formed in the portion so as to extend in a direction orthogonal to the conveying direction of the diaper continuous body 34.

  In the second embodiment, the irradiation points P of the two laser beams 51 are rotated by the galvanometer mirror 54 in order to form the two fused portions (side seal portions) 35 and 35 close to each other. The roll 2A is moved in the conveyance direction (direction B in FIG. 6) at the same speed as the rotation speed of the roll 2A and the conveyance speed of the diaper continuous body 34 (sheet laminated body), and is moved in a direction orthogonal to the conveyance direction. In FIG. 7, the locus of the point (irradiation point) where each of the two laser beams 51 hits the diaper continuous body 34 (sheet laminate) is indicated by PA. Further, in order to form two linearly fused portions, one laser irradiation mechanism may be used. In this case, the irradiation point PA is moved in the transport direction (direction B in FIG. 6) at the same speed as the transport speed of the diaper continuum 34 and is reciprocated by shifting the position in a direction perpendicular to the transport direction.

  According to the laser-type bonding apparatus 1A of the second embodiment and the method of manufacturing a sheet fusion body using the same, the laser-type bonding apparatus 1 of the first embodiment and the method of manufacturing a sheet fusion body using the same. The effect of.

Further, in the second embodiment, only a part of the peripheral surface is the laser light transmitting part, so that even if a relatively expensive laser transmitting material such as zinc selenium is used, it can be manufactured at low cost.
In addition, the diaper continuous body 34 after the two fusion parts (side seal parts) 35 and 35 are formed is cut between the two adjacent fusion parts 35 and 35 in a later step, and individually. It becomes a pants-type disposable diaper.

The use of the sheet fusion product obtained by the method for producing a sheet fusion product of the present invention or the laser-type bonding apparatus is not particularly limited, and can be used for various applications.
The sheet fusion product manufacturing method and the laser-type joining device can be used by being incorporated in the manufacturing process of the absorbent article as in the above-described embodiment, and the absorptivity is performed separately from the absorbent article manufacturing line. It can also be used for the manufacture of component parts of articles.

  The absorbent article is mainly used for absorbing and holding liquid discharged from the human body such as urine and menstrual blood. Examples of the absorbent article include disposable diapers, sanitary napkins, panty liners (downcome sheets), incontinence pads, and the like, but are not limited thereto, and are used for absorbing liquid discharged from the human body. Widely encompasses articles. The absorbent article typically includes a liquid-permeable top sheet, a liquid-impermeable or water-repellent back sheet, and a liquid-retaining absorbent body interposed between the two sheets. The absorbent article may further include various members according to specific uses of the absorbent article. Such members are known to those skilled in the art. For example, when the absorbent article is a disposable diaper, a sanitary napkin, or the like, a pair or two or more pairs of three-dimensional guards can be disposed on the left and right sides of the topsheet.

When the manufacturing method of the sheet fusion product of the present invention or the laser-type bonding apparatus is used for manufacturing the absorbent article and its constituent members, examples of the combination of two sheets include a front sheet, a back sheet, and a three-dimensional guard formation. Sheet and surface sheet, three-dimensional guard (three-dimensional gather) forming sheet and back sheet, surface sheet and sublayer disposed under the surface sheet, front sheet or back sheet and wing portion forming sheet. In addition, when a sheet laminate comprising two or more sheets is used as a sheet constituting the absorbent article, such as a front sheet, a back sheet, a three-dimensional guard forming sheet, a wing part forming sheet, the sheet lamination The sheet-fused body manufacturing method and laser-type bonding apparatus of the present invention can also be used for bonding sheets constituting the body. Regarding the method for manufacturing an absorbent article, points that are not particularly explained can be performed according to a conventional method.
It is also preferable to use the sheet fusion body at a part (liquid absorbing surface, solid guard, wing part, etc.) that comes into contact with the skin of the absorbent article. Moreover, it is also preferable from viewpoints of the touch etc. to use for the site | part which forms the outer surface of a diaper.

  As mentioned above, although several embodiment of this invention was described, this invention is not restrict | limited to embodiment mentioned above, In the range which does not deviate from the meaning of this invention, it can change suitably. For example, the sheet laminate may be a laminate of two, three, four, or even five to ten sheets, in addition to a laminate of two sheets. Further, the sheets to be fused may be two of three or more sheets.

  In addition, in the form in which a part of the circumferential surface of the rotating roll is a laser light transmitting part, a part in the circumferential direction is a laser light transmitting part, and a part in the rotation axis direction of the rotating roll is a laser light transmitting part. And a mode in which a part in the circumferential direction and a part in the direction of the rotation axis are a laser light transmitting part.

  Further, the pressure belt 41 in the case of using a belt-type pressure device may be one that spans two or four or more rolls instead of three rolls.

  The rotating roll is not limited to the one that is rotationally driven by rotating the shaft by a motor, and may be one that is rotationally driven by another mechanism. Furthermore, the roll of the pressure belt 41 may be rotationally driven, and the rotary roll 2 may be driven by the pressure belt 41 to rotate.

  Moreover, in one embodiment, the fused part 73a is bounded by the point where the fused part 7a has a tangent of 45 degrees with respect to both the conveying direction MD of the sheet laminate 3 and the orthogonal direction CD. When the component a in the direction CD perpendicular to the conveyance direction is larger than the component b in the conveyance direction MD of the sheet laminate 3, the irradiation point P of the laser beam 51 is moved in the rotation direction of the rotary roll 2. The movement in the rotation direction may be started by setting a threshold value for the speed and acceleration of the irradiation point P in the CD direction and MD direction, and the combined speed and acceleration of the irradiation point P. You may start at the rotational position.

  The description omitted in one embodiment described above and the requirements of only one embodiment can be applied to other embodiments as appropriate, and the requirements in each embodiment can be appropriately changed between the embodiments. Can be substituted.

1, 1A Laser type bonding device 2 Rotating roll 3 Sheet laminate 4 Belt type pressure device (pressure device)
41 Pressurizing belt 42 Heat generating surface (surface in contact with sheet laminate)
5 Laser irradiation mechanism 50 Irradiation head 51 Laser light 52 Carriage 53 Reflection mirror 6 Temperature control device 7 Sheet fusion body 8 Preheating device

Claims (7)

A sheet laminated body in which a plurality of sheets having laser beam transparency are stacked, a hollow rotating roll having a laser beam transmitting portion that transmits the laser beam on the peripheral surface, and heat generated by absorbing the laser beam. Convey while pressing between the heat generation surface,
Heat is transferred from the heat generating portion on the heat generating surface that is irradiated with the laser light from the inside of the rotating roll to the heat generating surface that moves while being in contact with the sheet laminate being conveyed. A method for producing a sheet fusion body, in which the sheets in the sheet laminate are fused together.   2. The sheet fusion according to claim 1, wherein the sheets in the sheet laminate are fused together while moving the irradiation point of the laser beam in a conveyance direction of the sheet laminate and / or a direction orthogonal to the conveyance direction. A manufacturing method of a kimono.   The method for producing a sheet fusion body according to claim 1 or 2, wherein the heat generating surface brought into contact with the sheet laminate is controlled to a temperature lower than the melting point of the sheet in the sheet laminate.   The manufacturing method of the sheet fusion body in any one of Claims 1-3 which preheats the said sheet laminated body to temperature lower than melting | fusing point of the sheet | seat in this sheet laminated body. A hollow rotating roll, which is a laser light transmitting portion that allows the entire or a part of the peripheral surface to transmit laser light, and a sheet laminate in which a plurality of sheets are stacked are pressed against the peripheral surface of the rotating roll and pressed. A pressure device provided with a possible pressure belt, and a laser irradiation mechanism for irradiating laser light from the inside to the outside of the rotating roll,
The laser-type bonding apparatus, wherein a surface of the pressure belt that is brought into contact with the sheet laminate is a heat generating surface that absorbs heat with respect to the laser light.   The laser-type bonding apparatus according to claim 5, wherein the laser irradiation mechanism is configured to move a laser beam irradiation point in a direction orthogonal to the conveyance direction while moving the laser beam irradiation point in the conveyance direction of the sheet laminate.   A manufacturing method of an absorptive article including the process of manufacturing a sheet fusion object by the manufacturing method of the sheet fusion object according to any one of claims 1 to 4, or the laser type joining device according to claim 5 or 6.

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