U.S. patent application number 10/622763 was filed with the patent office on 2004-01-29 for method for manufacturing disposable worn article.
Invention is credited to Ichiura, Yuzo, Inoue, Kiyofumi, Nakakado, Masaki, Tachibana, Ikuo, Tanaka, Satoshi, Tanaka, Yoshinari.
Application Number | 20040016500 10/622763 |
Document ID | / |
Family ID | 25528050 |
Filed Date | 2004-01-29 |
United States Patent
Application |
20040016500 |
Kind Code |
A1 |
Tachibana, Ikuo ; et
al. |
January 29, 2004 |
Method for manufacturing disposable worn article
Abstract
A method for manufacturing a disposable worn article of the
present invention includes: a first step of applying an adhesive on
at least one of a first web and a second web; a second step of
sandwiching an elastic member between the first and second webs and
combining the first and second webs and the elastic member
together, thereby producing a combined web; and a third step of
melting a portion of at least one of the first and second webs and
a portion of the elastic member, thereby reducing a shrinking force
of the elastic member in the melted portion.
Inventors: |
Tachibana, Ikuo; (Hyogo,
JP) ; Inoue, Kiyofumi; (Hyogo, JP) ; Ichiura,
Yuzo; (Osaka, JP) ; Tanaka, Yoshinari; (Osaka,
JP) ; Nakakado, Masaki; (Osaka, JP) ; Tanaka,
Satoshi; (Osaka, JP) |
Correspondence
Address: |
RENNER OTTO BOISSELLE & SKLAR, LLP
1621 EUCLID AVENUE
NINETEENTH FLOOR
CLEVELAND
OH
44115
US
|
Family ID: |
25528050 |
Appl. No.: |
10/622763 |
Filed: |
July 18, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10622763 |
Jul 18, 2003 |
|
|
|
09981034 |
Oct 17, 2001 |
|
|
|
Current U.S.
Class: |
156/179 ;
156/269; 156/301 |
Current CPC
Class: |
Y10T 156/1084 20150115;
A61F 13/15593 20130101; G06F 1/1616 20130101; G06F 1/1688 20130101;
Y10T 156/1095 20150115; A61F 13/49009 20130101 |
Class at
Publication: |
156/179 ;
156/301; 156/269 |
International
Class: |
B32B 031/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 4, 2000 |
JP |
2000-237455 |
Claims
What is claimed is:
1. A method for manufacturing a disposable worn article, the method
comprising: a first step of applying an adhesive on at least one of
a first web and a second web; a second step of sandwiching an
elastic member between the first and second webs and combining the
first and second webs and the elastic member together, thereby
producing a combined web; and a third step of melting a portion of
at least one of the first and second webs and a portion of the
elastic member, thereby reducing a shrinking force of the elastic
member in the melted portion.
2. A method for manufacturing a disposable worn article, the method
comprising: a first step of applying an adhesive on at least one of
a first web and a second web; a second step of sandwiching an
elastic member between the first and second webs and combining the
first and second webs and the elastic member together, thereby
producing a combined web; and a third step of melting a portion of
at least one of the first and second webs and a portion of the
elastic member, thereby cutting off the elastic member.
3. A method for manufacturing a disposable worn article, the method
comprising: a first step of applying an adhesive on at least one of
a first web and a second web; a second step of sandwiching an
elastic member between the first and second webs and combining the
first and second webs and the elastic member together, thereby
producing a combined web; and a third step of cutting off a portion
of at least one of the first and second webs, and the elastic
member.
4. A method for manufacturing a disposable worn article according
to claim 1, wherein: the third step is performed by passing the
combined web between an embossing roll having a plurality of
protrusions and a counter roll; and an interval of the protrusions
in a direction of a rotation axis of the embossing roll is about 1
mm to 25 mm.
5. A method for manufacturing a disposable worn article according
to claim 2, wherein: the third step is performed by passing the
combined web between an embossing roll having a plurality of
protrusions and a counter roll; and an interval of the protrusions
in a direction of a rotation axis of the embossing roll is about 1
mm to 25 mm.
6. A method for manufacturing a disposable worn article according
to claim 3, wherein: the third step is performed by passing the
combined web between an embossing roll having a plurality of
protrusions and a counter roll; and an interval of the protrusions
in a direction of a rotation axis of the embossing roll is about 1
mm to 25 mm.
7. A method for manufacturing a disposable worn article according
to claim 1, wherein the third step is performed by passing the
combined web between an embossing roll having a lattice portion and
a counter roll.
8. A method for manufacturing a disposable worn article according
to claim 2, wherein the third step is performed by passing the
combined web between an embossing roll having a lattice portion and
a counter roll.
9. A method for manufacturing a disposable worn article according
to claim 3, wherein the third step is performed by passing the
combined web between an embossing roll having a lattice portion and
a counter roll.
10. A method for manufacturing a disposable worn article according
to claim 1, wherein a first charge is applied to an area of at
least one of the first and second webs where the adhesive is to be
applied, and a second charge different from the first charge is
applied to the adhesive to be applied.
11. A method for manufacturing a disposable worn article according
to claim 2, wherein a first charge is applied to an area of at
least one of the first and second webs where the adhesive is to be
applied, and a second charge different from the first charge is
applied to the adhesive to be applied.
12. A method for manufacturing a disposable worn article according
to claim 3, wherein a first charge is applied to an area of at
least one of the first and second webs where the adhesive is to be
applied, and a second charge different from the first charge is
applied to the adhesive to be applied.
13. A method for manufacturing a disposable worn article according
to claim 1, wherein: at least the first web includes a design area
having at least one of a graphical design, a symbol and a character
printed thereon; and the elastic member located on at least a
portion of the design area is cut off in the third step.
14. A method for manufacturing a disposable worn article according
to claim 2, wherein: at least the first web includes a design area
having at least one of a graphical design, a symbol and a character
printed thereon; and the elastic member located on at least a
portion of the design area is cut off in the third step.
15. A method for manufacturing a disposable worn article according
to claim 1, wherein: at least the second web includes an area on
which a member is to be adhered; and the elastic member located
under at least a portion of the area is cut off in the third
step.
16. A method for manufacturing a disposable worn article according
to claim 2, wherein: at least the second web includes an area on
which a member is to be adhered; and the elastic member located
under at least a portion of the area is cut off in the third
step.
17. A method for manufacturing a disposable worn article according
to claim 1, wherein the elastic member is at least one of a string
rubber, a flat rubber and a meshed rubber.
18. A method for manufacturing a disposable worn article according
to claim 2, wherein the elastic member is at least one of a string
rubber, a flat rubber and a meshed rubber.
19. A method for manufacturing a disposable worn article according
to claim 3, wherein the elastic member is at least one of a string
rubber, a flat rubber and a meshed rubber.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method for manufacturing
a disposable worn article using an elastic sheet.
[0003] 2. Description of the Related Art
[0004] Japanese Laid-Open Patent Publication No. 2000-26015
discloses a method for cutting off only an elastic member without
damaging a base material sheet by using a roll cutter having a
ridge-shaped blade thereon.
[0005] However, Laid-Open Patent Publication No. 2000-26015 fails
to disclose sealing the base material sheet while cutting off the
elastic member, improving the air permeability of the base material
sheet while cutting off the elastic member, etc.
SUMMARY OF THE INVENTION
[0006] A method for manufacturing a disposable worn article of the
present invention includes: a first step of applying an adhesive on
at least one of a first web and a second web; a second step of
sandwiching an elastic member between the first and second webs and
combining the first and second webs and the elastic member
together, thereby producing a combined web; and a third step of
melting a portion of at least one of the first and second webs and
a portion of the elastic member, thereby reducing a shrinking force
of the elastic member in the melted portion.
[0007] Another method for manufacturing a disposable worn article
of the present invention includes: a first step of applying an
adhesive on at least one of a first web and a second web; a second
step of sandwiching an elastic member between the first and second
webs and combining the first and second webs and the elastic member
together, thereby producing a combined web; and a third step of
melting a portion of at least one of the first and second webs and
a portion of the elastic member, there by cutting off the elastic
member.
[0008] Still another method for manufacturing a disposable worn
article includes: a first step of applying an adhesive on at least
one of a first web and a second web; a second step of sandwiching
an elastic member between the first and second webs and combining
the first and second webs and the elastic member together, thereby
producing a combined web; and a third step of cutting off a portion
of at least one of the first and second webs, and the elastic
member.
[0009] In one embodiment of the invention: the third step is
performed by passing the combined web between an embossing roll
having a plurality of protrusions and a counter roll; and an
interval of the protrusions in a direction of a rotation axis of
the embossing roll is about 1 mm to 25 mm.
[0010] In another embodiment of the invention, the third step is
performed by passing the combined web between an embossing roll
having a lattice portion and a counter roll.
[0011] In still another embodiment of the invention, a first charge
is applied to an area of at least one of the first and second webs
where the adhesive is to be applied, and a second charge different
from the first charge is applied to the adhesive to be applied.
[0012] Instill another embodiment of the invention: at least the
first web includes a design area having at least one of a graphical
design, a symbol and a character printed thereon; and the elastic
member located on at least a portion of the design area is cut off
in the third step.
[0013] In still another embodiment of the invention: at least the
second web includes an area on which a member is to be adhered; and
the elastic member located under at least a portion of the area is
cut off in the third step.
[0014] In still another embodiment of the invention, the elastic
member is at least one of a string rubber, a flat rubber and a
meshed rubber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a perspective view illustrating one embodiment of
the method of the present invention.
[0016] Each of FIG. 2A, FIG. 2B and FIG. 2C is a diagram
illustrating an example of a disposable worn article using a
combined web.
[0017] Each of FIG. 3A and FIG. 3B is a diagram illustrating an
example of a staggered emboss pattern.
[0018] FIG. 4 is a diagram illustrating how elastic members are cut
off.
[0019] FIG. 5 is a diagram illustrating how elastic members are cut
off.
[0020] FIG. 6 is a diagram illustrating an example of a lattice
emboss pattern.
[0021] FIG. 7A is a diagram illustrating an example of an adhesive
applicator, and each of FIG. 7B and FIG. 7C is a diagram
illustrating an example of a conductive portion thereof.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] A first embodiment of the present invention will now be
described with reference to the accompanying drawings.
[0023] FIG. 1 is a diagram illustrating a manufacturing apparatus 1
for manufacturing a disposable worn article according to the first
embodiment.
[0024] The manufacturing apparatus 1 includes an adhesive
applicator 13 for applying an adhesive on a first sheet 10, a guide
21 for guiding an elastic member 20 between the first sheet 10 and
a second sheet 30, press rolls 31 and 32 for pressing together the
first sheet 10 and the second sheet 30 into a combined web 40, and
a processing section 2 for cutting off at least a part of, or
reducing the shrinking force of, the elastic member 20 of the
combined web 40 produced through the press rolls 31 and 32. The
adhesive may be applied on the second sheet 30.
[0025] The adhesive applicator 13 is capable of applying an
adhesive on the first sheet 10, which has a strip shape of a
predetermined width and which is advanced in the X direction (the
direction of the production flow), so that an adhesive portion 11
and a non-adhesive portion 12 are provided on the first sheet 10.
In terms of the air permeability of the combined web 40, it is
preferred that the adhesive applicator 13 is a spray coater, a
curtain coater, a spiral coater, or the like. The amount of
adhesive is preferably about 1 g/m.sup.2 to about 20 g/M.sup.2. The
adhesive may be a hot melt. A specific example of the adhesive
applicator 13 will be described later.
[0026] The elastic member 20 under a predetermined tension is
supplied to the guide 21. The elastic member 20 may be in the form
of a plurality of lines, as illustrated in FIG. 1, or a mesh (e.g.,
elastomeric netting such as REBOUND(R) of CONWED PLASTICS may be
used). The elastic member 20 may be a string rubber or a flat
rubber. The guide 21 is capable of reciprocating transversely of
the direction of the production flow. In such a case, the guide 21
is capable of guiding the elastic member 20 between the first sheet
10 and the second sheet 30 so that the elastic member 20 is drawn
in a non-linear line. A predetermined tension is applied to the
elastic member 20 supplied to the guide 21 by means of a tension
roll (not shown).
[0027] The processing section 2 includes an embossing roll 50 and a
counter roll 60 facing the embossing roll 50. The combined web 40
is inserted between the embossing roll 50 and the counter roll 60,
and the processing section 2 cuts off at least a part of, or
reduces the shrinking force of, the elastic member 20. The
embossing roll 50 includes an embossing section 51 having a
plurality of protrusions. The protrusions may generate heat as will
be described later. In such a case, the amount of heat to be
generated is determined by the distance between the embossing roll
50 and the counter roll 60, the shape and/or the size of each
protrusion, the material, the cross-sectional area and/or the shape
of the elastic member 20, and/or the speed at which the combined
web 40 is advanced.
[0028] FIG. 2A to FIG. 2C illustrate an exemplary disposable worn
article made of the combined web 40, which has been passed through
the processing section 2. The disposable worn article illustrated
in FIG. 2A to FIG. 2C (e.g., disposable underpants or a disposable
diaper; hereinafter referred to simply as "underpants") includes a
design area 150 having a graphical design or characters printed
thereon. If the shrinking force of a part of the elastic member 20
on the design area 150 is not reduced or eliminated, the design
area 150 will be wrinkled by the force, thereby deteriorating the
appearance of the article.
[0029] Also in cases where a label having a graphical design or
characters printed thereon is attached to the combined web 40, the
label will have wrinkles due to the shrinkage of the elastic member
20, there by deteriorating the appearance of the article. Besides,
such wrinkles make it difficult to adhere, on the combined web 40,
a member such as a label, a tape used for fixing a diaper, a tape
used when disposing of the article having the combined web 40, etc.
Even if such a member is successfully adhered on the combined web
40 while the wrinkles are being smoothed out, it is difficult to
keep the adhesion between the combined web 40 and the member for a
long period of time due to the shrinkage of the elastic member
20.
[0030] Underpants 130 include the adhesive portion 11, the
non-adhesive portion 12 which has substantially the same width as
that of the design area 150, and the part of the elastic member 20
on the design area 150 is cut off. The shrinkage of the cut elastic
member 20 stops in the vicinity of the boundary between the
adhesive portion 11 and the non-adhesive portion 12. Where the
combined web 40 has the non-adhesive portion 12, it is preferred
that the embossing section 51 has at least two rows of protrusions
such that a portion of a protrusion in the first row overlaps a
portion of a protrusion in the second row in the direction of the
rotation axis of the embossing roll 50, in order to reduce or
eliminate the shrinking force of the elastic member 20 on the
design area 150. This is because it is not possible, with a single
row of protrusions, to cut off a portion of the elastic member 20
located between adjacent protrusions. Even with a single row of
protrusions, the elastic member 20 can be cut off if the
protrusions are in a slant arrangement. Alternatively, for example,
cutting off, etc., of a plurality of rubber strings can be achieved
with a single protrusion. The length L.sub.2 of the embossing
section 51 may be slightly smaller than the length L.sub.1 of the
non-adhesive portion 12.
[0031] In underpants 140, an adhesive is applied also in the design
area 150. In order to reduce or eliminate the shrinking force of
the part of the elastic member 20 on the design area 150, it is
preferred that the protrusions in each row are arranged at a
predetermined interval in the embossing section 51 across the
entirety of the design area 150. In other words, it is preferred
that the protrusions have an overlap with one another as they are
projected in the axial direction of the embossing roll 50.
[0032] While the elastic member 20 exists under the sheet, the
processing section 2 may be used to reduce or eliminate the
shrinking force of the elastic member 20 in advance in cases where
an additional member (e.g., a tape used when disposing of the
underpants or a tape to be attached to a diaper body or a label) is
adhered on the sheet. This is because it is difficult to fix such
an additional member on the sheet while the elastic member 20 is
shrunk.
[0033] Underpants 160 are made of a combined web having a meshed
elastic member 170 sandwiched between the first and second sheets
at a predetermined tension. In a waist area 161, the vertical
elastics are cut off while leaving the horizontal elastics (the
elastic around the waist) so that the underpants 160 fit well to
the body. Note however that the vertical and horizontal elastics
are both cut off in an area 162 where an additional member or a
label is adhered. Moreover, the vertical and horizontal elastics
are both cut off in a predetermined area 163. The predetermined
area 163 is an area where it is preferred that the underpants 160
do not shrink. An absorber may be provided in the area.
[0034] As described above, it is made possible to adhere a member
on the combined web 40 by reducing the shrinking force of the
elastic member 20 of the combined web 40 in areas where the member
is to be adhered. Possible methods for reducing or eliminating the
shrinking force of the elastic member 20 include: cutting off the
elastic member 20; reducing the shrinking force of the elastic
member 20; altering the molecular structure of the elastic member
20 (when the elastic member 20 is a rubber), and melting a part of
the combined web 40 and curing the melted part.
[0035] The protrusions may generate heat in order to reduce or
eliminate the shrinking force of the elastic member. In such a
case, the elastic member 20 is cut off by the protrusions melting
at least a part of the second sheet 30 and at least a part of the
elastic member 20. In this process, the first sheet and the second
sheet are sealed together. For example, in the case of the
underpants 130, the first sheet and the second sheet are sealed
together while the elastic member 20 is cut off. The wrinkling of
the elastic member 20 is improved when the shrinking force of the
elastic member 20 is reduced, even if the elastic member 20 is not
cut off.
[0036] Moreover, even if the protrusions do not generate heat, it
is possible to cut off the elastic member 20 via the second sheet
30 when the width of each protrusion is small (e.g., several
microns to about 0.5 mm). In this process, at least apart of the
second sheet 30 is cut by the protrusions, thereby increasing the
air permeability of the underpants 140. In addition to the design
area 150, a part of the elastic member 20 corresponding to an upper
waist area 151 and/or a leg area 152 of the underpants 140 may also
be opened by the protrusions.
[0037] The protrusions of the embossing section 51 will now be
described. FIG. 3A illustrates an emboss pattern including a
plurality of rectangular protrusions arranged in a staggered
pattern. The embossing section 51 includes: an n-1.sup.th row of
rectangular protrusions 53, 53 each having a length S.sub.1 and a
width W.sub.1 which are arranged in the axial direction of the
embossing roll 50 (indicated by a solid arrow) at intervals of a
distance D.sub.1; an n.sup.th row of protrusions 54, 54 each having
the same length (S.sub.1) and width (W.sub.1) as those of the
protrusions 53 which are arranged in the circumferential direction
of the embossing roll 50 (indicated by an outline arrow) at a
distance of M.sub.1 from the protrusions 53 so that the
longitudinal center line thereof passes through a point of
D.sub.1/2; and an n+1.sup.th row of protrusions 55, 55 having the
same shape as that of the protrusions 53 which are arranged in the
same manner as the protrusions 53. The number of protrusions in
each row may be determined based on, for example, the number of
elastic members to be cut off. The number of rows of protrusions
may be determined based on the length L.sub.1 of the non-adhesive
portion. Herein, n is a natural number, and "0 row" means there is
no row of protrusions.
[0038] In an alternative emboss pattern where n is a natural number
equal to or greater than 2, a protrusion in the n-1.sup.th row may
overlap with the protrusion in the n+1.sup.th row in the row
direction by at least 1 mm or more. In such a case, a protrusion in
the n-1.sup.th throw may not overlap with the protrusion in the
n.sup.th row or may overlap with the protrusion in the n.sup.th row
by about 0.5 mm to about 1 mm. In this way, the density of
protrusions in each row may be reduced as compared to the emboss
pattern illustrated in FIG. 3A, thereby facilitating the production
of the emboss roll.
[0039] With an emboss roll having such protrusions as described
above, as compared to an emboss roll having a single line blade,
the protrusions more easily cut into the combined web, whereby it
is possible to easily cut off the elastic member.
[0040] FIG. 3B shows a pattern in which diamond-shaped protrusions
are arranged in a staggered pattern. The embossing section 51
includes: a row of diamond-shaped protrusions 56, 56 each having a
long axis S.sub.2 and a short axis W.sub.2 which are arranged in
the axial direction of the embossing roll 50 (indicated by a solid
arrow) at intervals of a distance D.sub.2; another row of
protrusions 57, 57 each having the same diamond shape as the
protrusions 56 which are arranged in the circumferential direction
of the embossing roll 50 (indicated by an outline arrow) at a
distance of M.sub.2 from the protrusions 56 so that the short axis
thereof is collinear with a point of D.sub.2/2; and still another
row of protrusions 58, 58 each having the same shape as that of the
protrusions 56 which are arranged in the same manner as the
protrusions 56. Of course, also for this pattern, the number of
protrusions in each row may be determined based on, for example,
the number of elastic members to be cut off, and the number of rows
of protrusions may be determined based on the length L.sub.1 of the
non-adhesive portion.
[0041] The length S.sub.1 of the rectangular protrusions and the
length of the long axis S.sub.2 of the diamond-shaped protrusions
are both preferably in the range of 1 mm to 25 mm, and more
preferably 2 mm to 25 mm. Where the interval D.sub.1 between
adjacent protrusions is less than or equal to S.sub.1, the elastic
member located between adjacent protrusions 53 can be reliably cut
off by the protrusion 54 due to the staggered arrangement.
Similarly, D.sub.2 and S.sub.2 may be determined so that
D.sub.2<S.sub.2 holds. When S.sub.1 or S.sub.2 is less than 1
mm, the embossing section 51 may fail to cut off the elastic
member, and when it is greater than 25 mm, the feel/touch of the
article may deteriorate due to the excessive total area of seal
portions. D.sub.1 and D.sub.2 are also preferably in the range of 1
mm to 25 mm, and D.sub.1 is more preferably 2 mm to 25 mm. Where
diamond-shaped protrusions are used, if a protrusion in a row has
little overlap with the closest protrusion in an adjacent row in
the row direction, the elastic member may fall between adjacent
seal portions, and the embossing section 51 may thereby fail to cut
off the elastic member, depending upon the arrangement of the
protrusions. In view of this, D.sub.2 is more preferably 3 mm to 10
mm.
[0042] When a portion of the combined web is to be melted, the
width W.sub.1 of the rectangular protrusions and the length of the
short axis W.sub.2 of the diamond-shaped protrusions are preferably
0.5 mm to 15 mm. When the first sheet 10 and the elastic member are
cut off, W.sub.1 is preferably several microns to about 0.5 mm.
When they are greater than 15 mm, the feel/touch of the
manufactured article may deteriorate due to the excessive total
area of seal portions. The lower limit of W.sub.2 is preferably 1
mm or more.
[0043] While the distance between adjacent rows of protrusions is
not limited to any particular value, M.sub.1 or M.sub.2 is
preferably 1 mm to 25 mm. The protrusions may have a shape other
than a rectangular shape and a diamond shape as described above,
including a slanted rectangular shape, a circular shape, a
triangular shape, a star shape, a heart shape, a clover shape, a
crescent shape, other polygons, etc. The shape of the protrusions
maybe varied for different rows.
[0044] FIG. 4 schematically illustrates elastic members 22 and 23
having been cut off. It is assumed that the combined web is
advanced downwardly in FIG. 4. The area 11 is the adhesive portion
and the area 12 is the non-adhesive portion. The left-hand side
elastic member 22!is cut off by a seal portion 70 (corresponding to
the protrusion 53). An end portion 22a of the elastic member 22 is
released from the tension and shrink toward the elastic member 22
bonded on the sheet. If the remaining part of the elastic member is
caught by the protrusion 55 before completion of the cutting off by
the protrusion 53, an elastic member 22b between the protrusion 53
and the protrusion 55 shrinks toward a seal portion 72 when the
elastic member is cut off by the protrusion 53. If the cutting off
by the protrusion 53 is completed before the remaining part of the
elastic member is caught by the protrusion 55, the elastic member
22b will shrink toward the elastic member existing in the
downstream adhesive portion (not shown). The right-hand side
elastic member 23 is cut off by a seal portion 71 (corresponding to
the protrusion 54), and an end portion 23a thereof shrinks.
[0045] With the arrangement described above, the elastic member is
cut off and a large number of small seal portions are formed in the
non-adhesive portion, whereby the upper and lower sheets are bonded
together also in the non-adhesive portion. Since the seal portions
are separated from one another and each have a small size, they are
less likely to give discomfort to the wearer than when they are
provided as a continuous line even when they are heat-sealed into a
film.
[0046] An exemplary adhesive applicator will now be described.
[0047] FIG. 7A is a diagram illustrating an exemplary adhesive
applicator 13a. The adhesive applicator 13a includes a gun member
100 for spraying an adhesive (a hot melt in the following
description) while positively charging the hot melt, and a
conductive member 101 which is located under the first sheet 10 and
is grounded or negatively charged. Generally, not all of the hot
melt sprayed from the gun member 100 is attached to the sheet, but
a portion thereof is left floating in the air. However, by charging
the hot melt as described above, it is possible to efficiently
attach the hot melt to the sheet, and to reduce the amount of hot
melt to be scattered with respect to the width direction of the
sheet, thereby improving the widthwise precision. A voltage of the
same polarity as the hot melt maybe applied to portions where it is
not necessary to apply the hot melt.
[0048] It is possible to improve the positional precision of the
attachment of the hot melt in the flow direction, which is
transverse to the width direction, by controlling the period in
which the hot melt is output and the potential of the gun member
100 or the conductive member 101. The polarities of the applied
voltages maybe reversed from that described above.
[0049] The conductive member 101 may be provided in the form of a
plurality of plates 101a and 101b as illustrated in FIG. 7B. For
example, when the hot melt is applied on areas separated by a
predetermined interval by using a plurality of gun members 100, the
hot melt application maybe performed with the interval between
adjacent hot melt-applied areas being the interval between the
plates 101a and 101b.
[0050] Alternatively, the conductive member 101 may be provided in
the form of a roller 102 as illustrated in FIG. 7C. The roller 102
rotates in synchronism with the first sheet 10. The roller 102
includes a conductive portion 103 and a non-conductive portion 104.
As described above, the hot melt is charged to a potential of the
first polarity, and the conductive portion 103 is grounded or
charged to a potential of the opposite polarity to the first
polarity.
[0051] The shape of the conductive portion 103 is determined based
on the shape of the area of the first sheet 10 on which the hot
melt is to be applied. The gun member 100 is controlled to output
the hot melt a predetermined time before the leading edge of the
area on which the hot melt is to be applied passes by the gun
member 100, and to stop outputting the hot melt a predetermined
time before the trailing edge of the area on which the hot melt is
to be applied passes by the gun member 100. With such an
arrangement, it is possible to attach the hot melt to an area
substantially equal to the intended area on which the hot melt
should be applied. The roller 102 may be positioned upstream of the
gun member 100.
[0052] It is understood that the adhesive applicator as described
above may be used for manufacturing articles other than disposable
worn articles. Nothing may be sandwiched between the first sheet
and second sheet after the application of the hot melt, or a member
other than the web materials may be adhered by the hot melt after
the application of the hot melt.
[0053] The hot melt adhesive may be continuously applied without
providing an on-adhesive portion. This may be a more preferred
embodiment than when the adhesive portions and the non-adhesive
portions are alternately provided, because it is possible, in the
former embodiment, to further increase the production line speed.
The elastic member may be sandwiched between sheets on which an
adhesive has been continuously applied and then passed between the
embossing roll and the counter roll, so as to cut off only the
elastic member without cutting off the sheets. After the cutting
process, each elastic member 24 is held by two (or three or more)
seal portions 59 and 59, as illustrated in FIG. 5, while being
relaxed. Therefore, even when the coating of the hot melt adhesive
is continuous, the seal portion can be made non-elastic by changing
the type and/or amount of the hot melt adhesive and/or the spraying
direction thereof. It is believed that where the elastic member is
cut off by heat, the hot melt adhesive is re-melted and softened by
the heat of the embossing roll, so that the anchoring force on the
elastic member by the hot melt adhesive is reduced and the elastic
recovering force of the elastic member overcomes the anchoring
force, whereby the elastic member is bonded to the seal portion
while being relaxed.
[0054] Next, a second embodiment of the present invention will be
described. The second embodiment employs, instead of the embossing
roll having protrusions spaced apart from one another, an embossing
roll including depressions having a length of 1 mm to 25 mm and a
width of 0.5 mm to 15 mm and a latticed protrusion (ridges) having
a width of 0.5 mm to 5 mm. As illustrated in FIG. 6, the latticed
protrusion 63 includes a large number of ridges 61, 61, . . . ,
which are arranged in the form of parallel crosses, with each space
62 surrounded by the ridges 61 being a depression. W.sub.3 denotes
the width of each ridge, which is 0.5 mm to 5 mm. An excessively
large width of the ridges may deteriorate the feel/touch of the
manufactured article, while the ridges having a width smaller than
0.5 mm may possibly cut off the sheet. D.sub.3 is the length of
each depression, which is preferably 5 mm to 25 mm, and more
preferably 5 mm to 10 mm. M.sub.3 is the width of each depression,
which is preferably 5 mm to 25 mm, and more preferably 5 mm to 10
mm.
[0055] While FIG. 6 shows a slanted lattice pattern, the pattern
may alternatively be any other polygonal lattice pattern such as a
square lattice pattern or a rectangular lattice pattern. In this
embodiment, the seal portions are in a lattice pattern, whereby it
is possible to reliably cut off the elastic member. Moreover, since
the latticed protrusion made up of narrow ridges extends across a
sufficiently large area in a meshed pattern, the elastic member can
be cut off by any of the seal portions. Where the sealing is
provided by using a single line blade, all the elastic members need
to be cut off by the single line blade, whereby it is necessary to
perform strong sealing so that no elastic member is left uncut. As
a result, the sheet may possibly be cut off. With the
above-described arrangement, the elastic member can be cut off by
any of the seal portions. Therefore, the sheet will not be cut off
because it is not necessary to perform strong sealing and the
contact surface between the sheet and the protrusion is increased.
Moreover, such a latticed seal portion gives the wearer a soft
feel/touch, and also is aesthetically desirable. Also in the second
embodiment, the sheet may include hot melt adhesive portions and
non-adhesive portions, or the hot melt adhesive may be continuously
applied on the sheet without providing the non-adhesive
portions.
[0056] At least one of the embossing roll 50 and the counter roll
60 illustrated in FIG. 1 may include a heating member. Moreover,
other heating members such as a rod-shaped sheathed heater, a
high-frequency heating member, a far infrared heater, or an oil
heater, maybe additionally provided in the vicinity of these rolls.
In the arrangement of FIG. 1, the positions of the embossing roll
50 and the counter roll 60 may be reversed.
[0057] It is preferred that either the first sheet 10 or the second
sheet 30 is heat sealable. Applicable types of sheet include
non-woven fabric, a plastic film, knit fabric, woven fabric, paper,
etc. Applicable sheet materials include known materials such as a
polypropylene, a polyethylene, a polyester, a cellulose, a rayon,
etc., which can be used alone or in combination of two or more.
Each of the sheets 10 and 30 may be a multi-layer sheet including a
number of sheets laminated together. In such a case, a heat
sealable sheet should be provided on the uppermost surface of the
first sheet 10 or on the lowermost surface of the second sheet
30.
[0058] The elastic member may be made of a material that can be cut
off by heat (e.g., a thermoplastic polyurethane, an elastomer, a
rubber, etc.), and may be provided in the form of a ribbon or a
string. A film-shaped elastic member (e.g., an elastomer film) can
also be used because it can be reliably cut off by seal portions
arranged in a staggered pattern or a lattice pattern. It is
preferred that the elastic member has a melting point that is lower
than that of the heat sealable material of the second sheet so that
the second sheet will not be cut off. The melting point of the
second sheet may be higher than that of the first sheet.
[0059] While FIG. 1 illustrates an example where the elastic member
is adhered in the widthwise central portion of the sheet, the
elastic member may alternatively be adhered near the edge of the
sheet. In such a case, the emboss pattern can be changed according
to the position of the elastic member.
[0060] According to the present invention, the seal portions can be
made non-elastic after the heat seal process not only in the case
where an adhesive is applied so as to provide non-adhesive portions
and adhesive portions but also in the case where the adhesive
application is continuous. Therefore, an elastic sheet having
alternating elastic and non-elastic portions can be continuously
manufactured.
* * * * *