JP2008260131A - Method for manufacturing laminated stretchable sheet - Google Patents

Abstract

The present invention provides a method for producing a laminated stretchable sheet that more reliably forms a vent hole in an elastic sheet.
A step of forming a composite sheet by sandwiching a thermoplastic elastic sheet between at least two nonwoven fabrics containing thermoplastic fibers, and a plurality of overlapping portions of the composite sheet and the two nonwoven fabrics and the elastic sheet are formed. An ultrasonic bonding step of applying vibrational energy at the bonding point to weld the two nonwoven fabrics and the elastic sheet, and in the ultrasonic bonding step, only a part of the outer edge of the bonding point passes through the elastic sheet. A pore is formed.
[Selection] Figure 4

Description

  The present invention relates to a method for producing a laminated stretchable sheet.

  Conventionally, in a composite sheet used for disposable diapers and the like, a thermoplastic elastic sheet is disposed between two nonwoven fabrics in order to improve the fit of the diaper, particularly in a waist part of a pant-type diaper. There are also those using laminated stretchable sheets.

  Here, since the said elastic sheet does not have air permeability, it is necessary to form a vent hole in a laminated elastic sheet for the improvement of a wearer's wearing feeling and prevention of stuffiness. Therefore, a method of perforating a vent hole using a needle or the like in the elastic sheet can be considered. However, it is complicated because the perforation process is required separately.

On the other hand, a method of manufacturing a laminated stretchable sheet is proposed in which a composite sheet in which an elastic sheet is sandwiched between two nonwoven fabrics is joined to each other at a plurality of joining locations by ultrasonic joining and a vent is formed. (See Patent Document 1).
US 6,572,595 B1

  In Patent Document 1, the composite sheet is disposed between an ultrasonic horn and an anvil, and ultrasonic vibration is applied by the ultrasonic horn. As a result, the two nonwoven fabric layers are bonded to each other. However, it is described that the polymer material of the elastic member is captured thereby.

  That is, in the invention of Patent Document 1, a hole larger than the joining portion of the two nonwoven fabrics is formed in the elastic sheet during the ultrasonic joining, and the nonwoven fabrics are joined to each other through the hole. It is understood that a part of becomes a vent hole of the laminated stretchable sheet.

  However, when actually trying to form a hole in the elastic sheet using the method of Patent Document 1, since the elastic sheet is sandwiched between two nonwoven fabrics, it is heated by ultrasonic vibration. However, the elastic sheet itself loses elasticity and it is difficult to form holes.

  Accordingly, an object of the present invention is to provide a method for producing a laminated stretchable sheet that can reliably form a vent hole in a laminated stretchable sheet using a thermoplastic elastic sheet.

  The method for producing a laminated stretchable sheet of the present invention comprises a step of forming a composite sheet by sandwiching a thermoplastic elastic sheet between at least two nonwoven fabrics containing thermoplastic fibers, and the two nonwoven fabrics in the composite sheet; An ultrasonic bonding step of applying vibration energy to the overlapping portion of the elastic sheet at a plurality of bonding points to weld the two nonwoven fabrics and the elastic sheet, and in the ultrasonic bonding step, a part of the outer edge of the bonding point Only in this case, a vent hole is formed in the elastic sheet.

According to the present invention, in the ultrasonic bonding step, the two nonwoven fabrics and the elastic sheet are welded by giving the vibration energy to the bonding portion, and the outer edge of the bonding portion is partially broken to be elastic. Since the air holes are formed in the sheet, there is no need to separately form the air holes.
In addition, since the nonwoven fabric and the stretchable sheet are bonded using ultrasonic bonding without using an adhesive, there is no possibility that the adhesive will cause wrinkles and the like, and the wearing feeling and texture will not be impaired.
As the “elastic sheet”, for example, a film-like elastic sheet made of an elastic film or the like can be used.

In the present invention, the method further comprises a step of stretching while conveying the thermoplastic elastic sheet, and the ultrasonic bonding step is performed in a state where the elastic sheet sandwiched between the two nonwoven fabrics is stretched. preferable.
According to this aspect, since the ultrasonic vibration is applied to the elastic sheet in the stretched state, a cutting force is applied to the elastic sheet in a state where tension is applied to the elastic sheet. Vent holes can be formed in the elastic sheet.

In the present invention, the welding is performed between an anvil having a plurality of protrusions corresponding to the plurality of joints and conveying the composite sheet, and a horn for providing vibration energy to the composite sheet in cooperation with the anvil. A step is performed, and each of the protrusions is capable of facing the horn and includes a flat flat portion and an edge portion formed on an outer peripheral edge of the flat portion, and the edge portion via the composite sheet The vent is preferably formed by intermittent contact of the horn.
According to this aspect, when the horn that gives vibration energy contacts the edge portion of the anvil via the composite sheet, the elastic sheet is cut off by the edge portion, thereby forming the air hole more reliably. be able to.

In the present invention, the projection is formed on the outer periphery of a drum that rotates around a predetermined axis of the anvil, and the composite sheet is conveyed along with the rotation of the drum. It is preferable that the welding is performed between the protrusion and the horn and the air hole is formed in the elastic sheet.
According to this aspect, by forming the protrusion on the outer periphery of the rotating drum, the contact state of the protrusion with the horn changes with the rotation of the drum, so that a part of the columnar protrusion acts as an edge. Therefore, welding by the projection and formation of the air hole can be easily realized.

  The invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings, in which: However, the examples and figures are for illustration and description only and should not be used to define the scope of the present invention. The scope of the present invention is defined only by the claims. In the accompanying drawings, the same part numbers in a plurality of drawings indicate the same or corresponding parts.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Although this laminated elastic sheet can be used for various uses, in the following description, the case where this laminated elastic sheet is applied to a diaper will be described as an example. The diaper includes a torso that covers the wearer's torso and a crotch that covers the crotch of the wearer. The laminated stretchable sheet is used for the body portion.

Laminated elastic sheet W:
First, the cutting panel P shown in FIG. 1 is generated. The cut panel P is cut after the stretched elastic sheet F is superimposed on the first nonwoven fabric W1 serving as an inner sheet in contact with the skin surface of the wearer. In the cutting panel P, the cut first nonwoven fabric W1 and the elastic sheet piece F1 are bonded to each other in the first bonding regions A1, A1 at both ends in the longitudinal direction X, which are part of the overlapping portion.

  Next, the cutting panel P is arranged at predetermined intervals on the second nonwoven fabric W2 made of a continuous web to form a composite sheet W3 portion. In addition, the said cutting panel P is arrange | positioned in the surface which contact | connects a wearer's skin surface, and 2nd adhesion area | region A2, A2 of the both ends is adhere | attached on the 2nd nonwoven fabric W2.

  Therefore, the composite sheet W3 is in a state in which the thermoplastic elastic sheet piece F1 is sandwiched between the first and second nonwoven fabrics W1 and W2 including two thermoplastic fibers. In the composite sheet W3, both ends P2 of the elastic sheet piece F1 are bonded to the nonwoven fabrics W1 and W2 in the first and second bonding regions A1 and A2.

  At a plurality of joint locations M of the intermediate portion P1 of the composite sheet W3, both the surfaces of the composite sheet W3 are welded to the nonwoven fabrics W1 and W2 to form a laminated stretchable sheet W by the ultrasonic joining.

  As shown in FIG. 2C, the laminated stretchable sheet W is joined to the first nonwoven fabric W1 and the second nonwoven fabric W2, as shown in FIG. 2C, at the joining point M of the intermediate portion P1 of the composite sheet W3. As shown in FIG. 4, vent holes H1 and H2 are formed in the elastic sheet piece F1 in the portions Mc1 and Mc2 of the outer edge Mc of the joint location M.

Sealing device 1:
Next, an example of a sealing device used for the ultrasonic bonding will be described.
As shown in FIG. 3, the sealing device 1 has a large number of protrusions 21 corresponding to the plurality of joints M (FIG. 1), and cooperates with the anvil 20 that conveys the composite sheet W <b> 3. And a horn 10 for applying vibration energy to the composite sheet W3. The horn 10 has a flat front end surface.

  In the anvil 20, the protrusion 21 is formed on the outer periphery of a drum 20d that rotates around an axis including the point O, and the composite sheet W3 is conveyed in the flow direction X along with the rotation of the drum 20d. The protrusion 21 is formed at a position corresponding to the pattern of the joining portion M shown in FIG. 2C on the drum 20d.

  In FIG. 4A, FIG. 4B, and FIG. 4C, only one protrusion 21 is shown among the many protrusions 21. FIG. The protrusion 21 is formed in a substantially cylindrical shape, and can be opposed to the horn 10 and includes a flat flat portion 21b and edge portions 21a and 21c formed from the outer peripheral edge of the substantially cylindrical flat portion 21b. ing.

Production method:
First, the elastic sheet F shown in FIG. 1 is stretched in the longitudinal direction (flow direction) X while being conveyed.
On the other hand, the 1st nonwoven fabric W1 which forms a part of said trunk | drum and becomes an inner sheet | seat in contact with a wearer's skin surface is conveyed.

  An adhesive is applied in advance to the first bonding area A1 of the first nonwoven fabric W1, and the stretched elastic sheet F is placed on the first nonwoven fabric W1 so as to overlap the first bonding area A1 (overlapping). ), The elastic sheet F and the first nonwoven fabric W1 are bonded to each other by the adhesive.

The bonded first nonwoven fabric W1 and the elastic sheet F are cut to obtain a cut panel P including the elastic sheet piece F1.
Here, the first bonding area A1 is set at a predetermined equal interval, and after the bonding, the cutting panel P is cut by equally dividing the first bonding area A1 portion in the longitudinal direction X. Generated. Therefore, the cut | disconnected panel P mutually adhere | attaches the cut | disconnected 1st nonwoven fabric and elastic sheet piece F1 in 1st adhesion area | region A1, A1 of the both ends of the longitudinal direction X which is a part of the overlap part.

On the other hand, the 2nd nonwoven fabric W2 which consists of a continuous web used as a trunk | drum is conveyed in the longitudinal direction X of this 2nd nonwoven fabric W2.
The elastic sheet piece F1 is intermittently disposed on the second nonwoven fabric W2 in a state where the extension direction of the extended elastic sheet piece F1 is aligned with the longitudinal direction X.
Here, the second non-woven fabric W2 is preliminarily coated with an adhesive at predetermined equal intervals, and the second adhesive region A2 composed of both end portions in the longitudinal direction X of the elastic sheet piece F1 is second in the arrangement. The nonwoven fabric W2 is bonded with the adhesive.

By arranging the cutting panel P with respect to the second nonwoven fabric W2, a composite sheet W3 portion is generated in which an elastic sheet piece F1 in an expanded state is sandwiched between the two nonwoven fabrics W1 and W2. Both ends P2 of the elastic sheet piece F1 are bonded to the first nonwoven fabric W1 and the second nonwoven fabric W2 by the first bonding regions A1, A1 and the second bonding regions A2, A2, respectively. The intermediate part P1 between the parts P2 is not yet bonded to both nonwoven fabrics W1 and W2.
For ease of explanation, the first adhesive region A1 and the second adhesive region A2 are illustrated so as not to overlap each other, but the two adhesive regions A1, A2 may overlap. In addition, since the area | region which expands / contracts becomes narrow when two adhesion area | regions A1 and A2 do not overlap, it is more preferable that two adhesion area | regions A1 and A2 overlap. As the adhesive, for example, a hot melt resin can be used.

Thereafter, vibration energy is given by the sealing device 1 to the overlapping portion between the intermediate portion P1 and the nonwoven fabrics W1 and W2 in the elastic sheet piece F1, and the two nonwoven fabrics W1 and W2 and the elastic sheet F in an expanded state Are welded to each other at a plurality of joints M. A laminated stretchable sheet W is generated by the welding.
On the other hand, at the time of welding, as shown in FIGS. 2A and 2B, vent holes H1 and H2 are formed at both end portions in the longitudinal direction X of the outer edge Mc of the joining point M of the elastic sheet F.

Formation principle of vent holes H1, H2:
Next, the principle of forming the vent holes H1 and H2 will be described with reference to FIGS. 4A, 4B and 4C. In the following description, the composite sheet W3 is omitted with a single solid line, and the one protrusion 21 is illustrated as an example.

  4A, first, when one protrusion 21 starts to face the horn 10, only a part of the protrusion 21 contacts the horn 10 via the composite sheet W3 due to the curvature of the drum 20d. That is, the elastic sheet F shown in FIG. 2A is brought into contact with the vibrating horn 10 by contacting the front portion (the downstream end portion in the rotation direction of the drum 20d) of the outer peripheral edge of the edge portion of the protrusion 21 at the contact portion. The slit is formed in the stretched elastic sheet F by cutting, and the slit expands in the stretch direction (longitudinal direction X) by the tension of the elastic sheet to form the first vent hole H1.

  Thereafter, as shown in FIG. 4B, the drum 20d rotates, the flat portion 21b of the protrusion 21 contacts the vibrating horn 10, and the nonwoven fabrics W1, W2 and the elastic sheet F are ultrasonically welded to each other.

  After the welding, as shown in FIG. 4C, when the drum 20d further rotates, the rear portion 21c of the outer peripheral edge of the edge portion of the protrusion 21 contacts the vibrating horn 10, and similarly, the elastic sheet F shown in FIG. By cutting at the contact portion, the second ventilation hole H2 is formed in the elastic sheet F.

Therefore, as shown in FIG. 2B, the elastic sheet F is formed with a joint portion M that is welded to the nonwoven fabrics W1 and W2, and only the front and rear in the flow direction X of the outer edge Mc of the joint portion M are cut. Vent holes H1 and H2 are formed by the cut portions Mc1 and Mc2. Here, as described above, since the elastic sheet F is conveyed in an extended state, when a cutting force is applied by the edge portions 21a and 21c, the elastic sheet F is easily cut and slit by the edge portions 21a and 21c. By being cut into a shape, the vent holes H1 and H2 are slightly expanded in the flow direction X as shown in FIG.
Thereafter, a crotch portion (not shown) is bonded to the laminated stretchable sheet W and cut into individual diapers.

Next, the diameter D1 and the horn width D2 of the drum 20d in FIG. 3 will be considered.
As described above, in order for the front and rear in the rotation direction of the protrusion 21 to act as edges, the diameter D1 of the drum 20d needs to be small to some extent, and the width D2 of the horn 10 has to be large to some extent.
On the other hand, the diameter D1 of the drum 20d needs to be larger than a certain degree due to a problem in strength.

  From this viewpoint, the diameter D1 of the drum 20d is preferably 50 mm to 400 mm, and most preferably 100 mm to 300 mm. The horn width D2 is preferably 10 mm to 40 mm, and most preferably 15 mm to 30 mm.

On the other hand, as the thickness of the elastic sheet F, a thin film-like material having a thickness of 20 μm to 300 μmm can be used, preferably 30 μm to 200 μmm, and most preferably 40 μm to 100 μmm.
If the film is thick, the economical efficiency and the cutability are lowered. On the other hand, if the film is thin, the feeling of wearing is improved, but the strength is lowered, and there is a possibility that breakage may occur during ultrasonic bonding.

As described above, when the edge portions 21a and 21c of the protrusion 21 are in contact with the vibrating horn 10, vent holes H1 and H2 are formed in a part of the outer edge Mc of the joining portion M of the nonwoven fabrics W1 and W2 and the elastic sheet F. The
Accordingly, it is possible to greatly reduce the adhesive made of hot melt resin and the like, so that the manufacturing cost can be reduced. Moreover, the fall of the texture of a laminated elastic sheet can be prevented by the said adhesive agent being reduced.

Furthermore, in the ultrasonic bonding process, the air holes H1 and H2 are formed in the elastic sheet F, so that a process step for the air holes is not required separately.
Further, by changing the arrangement of the joints M by changing the arrangement of the protrusions 21 on the drum 20d, the expansion / contraction ratio of the laminated elastic sheet can be set to a predetermined value.
Further, since the laminated stretchable sheets are joined by ultrasonic joining, damage to the elastic sheet F due to heat can be reduced as compared with the case where thermocompression bonding (heat sealing) is performed.

  In addition to the cylindrical shape described above, various shapes are conceivable as the shape of the protrusion 21. When a drum is not used as the anvil, for example, the front of the edge 21 of the protrusion 21 in the flow direction X and / or Or it is necessary to make it the shape which made the back protrude toward the horn 10. FIG.

Joining pattern:
Next, the relationship between the expansion / contraction rate of the elastic sheet F and the bonding pattern will be described.
FIG. 5A shows the laminated stretchable sheet W in the stretched state, and FIG. 5B shows the laminated stretchable sheet W in a state where the stretched force is released to a free length.
In the expansion / contraction direction X, the length A of the joining portion M, the length B of the non-joining portion, and the expansion / contraction ratio of the elastic sheet F at the time of bonding are expressed by the following formula (1) for the expansion / contraction ratio C: C1 It is represented by
Expansion / contraction ratio = C: C1 = A + B: A + B1 (1)
However, A = the length of the joining point M B = the length of the non-joining part B1 = the length of the non-joining part in a free length state

A joining pattern composed of the arrangement of the joining places M can be freely designed in terms of productivity and decoration as long as the expression (1) is satisfied.
For example, when emphasizing productivity, high-speed production is possible by reducing the length A of the joint M.
On the other hand, when emphasizing the decorativeness, various designs can be given to the laminated stretchable sheet W by changing the arrangement of the joint portions M such as a line shape, a curve shape, a dot shape, a character, and a pattern.

Note that an elastic sheet F slit in the longitudinal direction (flow direction) X, an elastic sheet F cut so as to cross the flow direction X, or a plurality of thread-like elastic sheets F may be used. Good.
Furthermore, functionality may be improved by controlling the expansion / contraction rate of the laminated stretchable sheet W by partially changing the arrangement of the joining points M.

  Note that it is not always necessary to convey the elastic sheet F in an expanded state, and the composite sheet W3 may be welded and the vent holes H1 and H2 may be formed in a state where the elastic sheet F has a free length. In such a case, it is preferable to use nonwoven fabrics W1 and W2 that can be stretched in the longitudinal direction X.

  The present invention can be employed in, for example, a method for producing a laminated stretchable sheet used for a worn article or the like.

It is a schematic perspective view which shows the manufacturing method of the laminated elastic sheet concerning one Example of this invention. 2A is a schematic sectional view of the composite stretchable sheet, FIG. 2B is a schematic plan view of the elastic sheet, and FIG. 2C is a schematic plan view of the composite stretchable sheet. It is a schematic side view which shows a sealing device. It is a schematic side view which shows the manufacturing method of a laminated elastic sheet. It is a schematic plan view which shows the expansion | extension rate of a laminated elastic sheet.

Explanation of symbols

10: Horn 20: Anvil 20d: Drum 21: Protrusion 21a, 21c: Edge part 21b: Flat part F: Elastic sheet H1, H2: Ventilation hole M: Joint location Mc: Outer edge W1, W2: Nonwoven fabric W3: Composite sheet

Claims (4)

A method for producing a laminated elastic sheet,
Forming a composite sheet by sandwiching a thermoplastic elastic sheet between at least two nonwoven fabrics containing thermoplastic fibers;
An ultrasonic bonding step in which vibration energy is applied at a plurality of bonding points to an overlapping portion of the two nonwoven fabrics and the elastic sheet in the composite sheet, and the two nonwoven fabrics and the elastic sheet are welded.
In the ultrasonic bonding step, a method for producing a laminated stretchable sheet, wherein a vent hole is formed in the elastic sheet only at a part of the outer edge of the bonded portion.   The lamination according to claim 1, further comprising a step of stretching while conveying the thermoplastic elastic sheet, wherein the ultrasonic bonding step is performed when the elastic sheet sandwiched between the two nonwoven fabrics is stretched. A method for producing an elastic sheet. 3. The method according to claim 1, wherein a plurality of protrusions corresponding to the plurality of joints are provided between the anvil that conveys the composite sheet and a horn that provides vibration energy to the composite sheet in cooperation with the anvil. The welding process is performed in
Each of the protrusions can face the horn, and includes a flat flat portion, and an edge portion formed on an outer peripheral edge of the flat portion,
The manufacturing method of the laminated elastic sheet in which the said air hole is formed when the said horn contacts the said edge part intermittently through the said composite sheet. In Claim 3, the protrusion is formed on the outer periphery of the drum that rotates around the predetermined axis of the anvil,
The composite sheet is transported with the rotation of the drum, and the composite sheet is welded between the protrusion and the horn during the transport, and the vent hole is formed in the elastic sheet. Manufacturing method.

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