Title: Method and apparatus for opening continuous filaments
Abstract: A method and an apparatus for opening continuous filaments provide stable quality of fibrous layer after opening crimped TOW. The TOW is transported by means of a plurality of rolls. While transported, the TOW is applied a resistance on one side of the TOW by slidingly contacting a sliding body onto the TOW at between rolls. As a result, continuous filaments stacked in a thickness direction of the TOW are caused to sift in a transporting direction of the TOW. Thus, the TOW is opened and the continuous filaments are spread in a width direction of the TOW.
Patent Number: 7,003,856 Issued on 02/28/2006 to Hayashi, et al.
| Inventors:
|
Hayashi; Hiroo (Kagawa, JP);
Furuya; Kodai (Kagawa, JP)
|
| Assignee:
|
Uni-Charm Corporation (Kawanoe, JP)
|
| Appl. No.:
|
935407 |
| Filed:
|
August 23, 2001 |
Foreign Application Priority Data
| Sep 01, 2000[JP] | 2000-265458 |
| Current U.S. Class: |
28/282 |
| Current Intern'l Class: |
D01D 11/02 (20060101) |
| Field of Search: |
28/282,283,220,219,248,240,241,247,259,260,278
19/65.T,66.T,65.A
264/168,280,282-285,290.2,290.5,290.7,299,292,288.4,69-71
|
References Cited [Referenced By]
U.S. Patent Documents
| 2244203 | Jun., 1941 | Kern.
| |
| 2790208 | Apr., 1957 | Smith.
| |
| 2801455 | Aug., 1957 | McLellan.
| |
| 2811770 | Nov., 1957 | Young, Jr.
| |
| 3345697 | Oct., 1967 | Aspy, Jr.
| |
| 3438104 | Apr., 1969 | Stoller.
| |
| 3501811 | Mar., 1970 | Watson.
| |
| 3739564 | Jun., 1973 | King.
| |
| 3865565 | Feb., 1975 | Spence et al.
| |
| 4509452 | Apr., 1985 | Pryor.
| |
| 5000807 | Mar., 1991 | Stuart.
| |
| 5042122 | Aug., 1991 | Iyer et al.
| |
| 5146651 | Sep., 1992 | Duffy et al.
| |
| 5214828 | Jun., 1993 | Neuert et al.
| |
| 6049956 | Apr., 2000 | Lifke et al.
| |
| 6687564 | Feb., 2004 | Baudry et al.
| |
| 6743392 | Jun., 2004 | Tanaka et al.
| |
| Foreign Patent Documents |
| 586060 | Sep., 1933 | DE.
| |
| 586060 | Oct., 1933 | DE.
| |
| 586060 | Oct., 1933 | DE.
| |
| 1921182 | Nov., 1970 | DE.
| |
| 1921182 | Nov., 1970 | DE.
| |
| 42 21 163 | Jan., 1993 | DE.
| |
| 1 230 122 | Apr., 1971 | GB.
| |
Other References
Database WPI, Section C, Week 197527 Derwent Publications Ltd., London GB; AN
1975-45381W, XP002250616 & JP 50 015884B (Daicel Ltd.) Jun. 9, 1975, Abstract.
Australian Search Report.
Derwent Abstract Accession No. 35261W/21, JP 50-010962 A (Teijin KK), Apr. 25,
1975, Abstract and Figure.
Derwent Abstract Accession No. 45381W/27, JP 50-015884 A (Deicel KK), Jun. 9,
1975, Abstract and Figure.
|
Primary Examiner: Vanatta; Amy B.
Attorney, Agent or Firm: Darby & Darby
Claims
What is claimed is:
1. An opening method for continuous filaments, comprising the steps of:
transporting crimped tow by means of a plurality of rolls; and
applying a resistance on at least one side of said tow by slidingly contacting
a plurality of sliding bodies onto said tow at a position between said rolls, whereby
continuous filaments stacked in a thickness direction of said tow are caused to
shift in a transporting direction of said tow to open said tow and to spread said
continuous filaments in a latitudinal direction of said tow, wherein
each side of said tow is slidingly contacted by at least one of said sliding
bodies, and each sliding body is adjustable about a tilt angle relative to a line
perpendicular to a transporting path of said tow and a penetration amount into
the transporting path of said tow.
2. The opening method for continuous filaments as set forth in claim 1 further
comprising the step of:
detecting a width of spread continuous filaments after slidingly contacting with
said sliding bodies, and
automatically adjusting said tilt angle and said penetration amount of said sliding
bodies based on a detected value.
3. The opening method for continuous filaments as set forth in claim 1, wherein
peripheral speeds of rolls located at an upstream side and a downstream side of
said sliding body are identical.
4. The opening method for continuous filaments as set forth in claim 1, wherein,
among rolls located at an upstream side and a downstream side of said sliding body,
a peripheral speed of the roll located at the downstream side is set higher than
that of the roll located at the upstream side for applying tension force on said
tow between the rolls.
5. An opening apparatus for continuous filaments, comprising:
a transporting roll group for transporting crimped tow of continuous filaments;
a plurality of sliding bodies arranged between rolls of said transporting roll
group so that each side of said tow is slidingly contacted by at least one of said
sliding bodies;
detecting means for detecting a width of spread continuous filaments after slidingly
contacting with said sliding bodies;
adjusting means for adjusting a tilt angle of each sliding body relative to a
line perpendicular to a transporting path of said tow and a penetration amount
of each sliding body into the transporting path of said tow; and
control means for controlling said adjusting means for varying said tilt angle
and said penetration amount of each sliding body based on a value detected by said
detecting means.
6. The opening apparatus for continuous filaments as set forth in claim 5, wherein
said rolls located at an upstream side and a downstream side of said sliding body
are driven to rotate at an identical peripheral speed.
7. The opening apparatus for continuous filaments as set forth in claim 5, wherein,
among rolls located at an upstream side and a downstream side of said sliding body
and driven to rotate, a peripheral speed of the roll located at the downstream
side is set higher than that of the roll located at the upstream side.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a method and an apparatus for opening
crimped TOW to prepare opened continuous filaments, to be used as a surface layer
of an absorbent article, such as sanitary napkin, or for other application.
2. Description of the Related Art
For a surface layer of an absorbent article, such as sanitary napkin, conjugated
synthetic fibers of core-sheath structure, such as those of PE/PP, PE/PET or the
like are used. As the conjugated synthetic fibers, continuous filaments may be used.
The continuous filaments are supplied to a manufacturing process of absorbent
article or so forth in a form of TOW, in which filaments are bundled to firmly
contact with each other and are crimped. In the manufacturing process, opening
process is preformed to separate the continuous filaments from each other in the
width direction of the TOW and to increase apparent width. The continuous filaments
thus separated in the width direction in the opening process to have a uniform
bulkiness, are used for production of the surface layer of the absorbent article
or the like.
Conventionally, the following method is employed for opening the TOW.
At first, the TOW is supplied to a transporting roll group which is constructed
such that downstream side roll has higher peripheral speed than that of upstream
side roll for applying tension force to the TOW between the rolls. Then, the TOW
is transferred to a transporting roll group which is constructed such that downstream
side roll has lower peripheral speed than that of the upstream side roll for releasing
the tension force. Application of tension force and release of tension force are
effected, respectively at least one time. In this method, the tension force is
applied to the continuous filaments forming the TOW for stretching crimp, and then,
the filaments are elastically contracted to restore crimp. By stretching crimp
and restoring crimp, the continuous filaments are given dispersing force in the
width direction of the TOW.
As an alternation, there is another method for opening the TOW, in which a threaded
roll formed with circumferentially extending grooves at a given pitch in the axial
direction, is driven to rotate and the TOW is supplied onto the surface of the
rotating threaded roll for opening. In this method, tension forces to be applied
to the continuous filaments are varied between portions of the threaded roll where
the grooves are present and portions of the threaded roll where the grooves are
not present. By variation of tension force, the continuous filaments forming the
TOW are locally stretched and locally contracted and whereby to apply dispersion
force in the width direction of the TOW.
In the further alternative, there is still another method for opening the TOW,
in which an air jet is applied along longitudinal direction of the TOW. In this
method, by blowing force of air, dispersing force of the continuous filaments is
applied in the width direction of the TOW.
However, in the method where different peripheral speeds are provided for
rolls in the transporting roll group, opening condition of the TOW depends on the
peripheral speeds of the rolls, nip pressure of the rolls, materials of the roll
surfaces and the like. Similarly, in the method employing the threaded roll, opening
condition depends on nip pressure of the roll, material of the surface of the roll,
size of each groove and the like.
Accordingly, when bundling condition of the TOW, basis weight of the
TOW, fineness of continuous filaments or material of continuous filaments is varied,
optimal opening may sometimes be impossible under the same condition. In such case,
preparatory operation for varying various conditions is quite difficult and huge
amount of cost is required for varying facility configuration.
On the other hand, in the method where the TOW is opened by air jet, since continuous
filaments are separated by air flow, it is difficult to achieve uniformity in opening.
SUMMARY OF THE INVENTION
The present invention has been worked out in view of the problem set forth above.
Therefore, it is an object of the present invention to provide a method and an
apparatus for opening continuous filaments, which can uniformly open crimped TOW
and can easily vary opening condition even when material or kind of TOW is varied.
According to a first aspect of the invention, there is provided an opening
method of continuous filaments, comprising the steps of:
transporting crimped TOW by means of a plurality of rolls; and
applying a resistance on at least one side of the TOW by slidingly contacting
at least one sliding body onto the TOW at between rolls, whereby continuous filaments
stacked in a thickness direction of the TOW are caused to sift in a transporting
direction of the TOW to open the TOW and to spread the continuous filaments in
a width direction of the TOW.
According to the opening method of the invention, by pushing the sliding
body (for example, of a plate shape) against the TOW to make the TOW slidingly
contact with the sliding body, a shifting force in the transporting direction of
the TOW can be effectively applied to the continuous filaments in the thickness
direction of the TOW, to thereby open the TOW. When the continuous filaments are
separated from one another by opening, repulsive forces are caused between adjacent
filaments due to contact between peaks and bottoms of crimps, so that the filaments
are effectively spread in the width direction of the TOW.
It is preferred that a plurality of sliding bodies are provided in the resistance-applying
step, and that each side of the TOW is slidingly contacted by at least one of the
sliding bodies.
It is also preferred that each sliding body is adjustable of a tilt angle relative
to a line perpendicular to transporting path of the TOW and a penetration amount
into the transporting path of the TOW. The adjusting operation may be performed
manually, but it is preferred that the opening method further comprises a step
of detecting a width of spread continuous filaments after slidingly contacting
with the sliding bodies, and a step of automatically adjusting the tilt angle and
the penetration amount of the sliding bodies on the basis of the detected value.
Peripheral speeds of rolls located at upstream side and downstream side
of the sliding body may be the same. But, it is preferred that among rolls located
at upstream side and downstream side of the sliding body, the peripheral speed
of the roll located at downstream side is set higher than that of the roll located
at upstream side for applying tension force on the TOW between the rolls.
According to another aspect of the invention, there is provided an opening
apparatus of continuous filaments, comprising:
a transporting roll group for transporting crimped TOW of continuous filaments; and
at least one sliding body arranged between rolls of the transporting roll group
for slidingly contacting with the TOW to be transported.
This opening apparatus may be constructed such that at least one sliding body
is provided on one side of the TOW and at least one sliding body is provided on
the other side of the TOW.
It is preferred that the opening apparatus further comprises:
detecting means for detecting a width of spread continuous filaments after
slidingly contacting with the sliding body;
adjusting means for adjusting a tilt angle of the sliding body relative
to a line perpendicular to transporting path of the TOW and a penetration amount
of the sliding body into the transporting path of the TOW; and
control means for controlling the adjusting means for varying the tilt angle
and the penetration amount of the sliding body on the basis of the detected value
by the detecting means.
The rolls located at upstream side and downstream side of the sliding body may
be driven to rotate at the same peripheral speed. But, it is preferred that among
rolls located at upstream side and downstream side of the sliding body and driven
to rotate, the peripheral speed of the roll located at downstream side is set higher
than that of the roll located at upstream side.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be understood more fully from the detailed description
given hereinafter and from the accompanying drawings of the preferred embodiment
of the present invention, which, however, should not be taken to be limitative
to the invention, but are for explanation and understanding only.
In the drawings:
FIG. 1 is an explanatory illustration for showing a method and an apparatus
for manufacturing a surface layer of an absorbent article including an opening
method and an opening apparatus according to the present invention;
FIG. 2 is an enlarged perspective view of the opening method and opening apparatus
of FIG. 1;
FIG. 3 is an enlarged side elevation showing a contact condition between a sliding
plate and TOW;
FIG. 4 is a partial side elevation showing another embodiment of the opening
method and the opening apparatus;
FIG. 5 is a partial side elevation showing still another embodiment of the opening
method and the opening apparatus;
FIG. 6 is a perspective view showing one example of an absorbent article;
FIG. 7 is a plan view of a surface layer of the absorbent article; and
FIG. 8 is a section of the absorbent article and the surface layer.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention will be discussed hereinafter in detail in terms of the
preferred embodiment of the present invention with reference to the accompanying
drawings. In the following description, numerous specific details are set forth
in order to provide a thorough understanding of the present invention. It will
be obvious, however, to those skilled in the art that the present invention may
be practiced without these specific detailed. In the other instance, well known
structure are not shown in detail in order to avoid unnecessary obscurity of the
present invention.
FIG. 1 is an explanatory illustration for showing a method and an apparatus
for manufacturing a surface layer of an absorbent article including opening method
and opening apparatus according to one embodiment of the present invention, and
FIG. 2 is an enlarged perspective view of the opening method and opening apparatus
of FIG.
1.
In opening process
1 of continuous filaments shown in FIGS. 1 and 2, TOW
2A, in which continuous filaments are bundled and crimped, is supplied and
opened to be uniform in width direction.
Continuous filaments forming TOW
2A may be conjugated synthetic
fibers of core-sheath structure, such as those of PE/PET, PE/PP or the like, side-by-side
type conjugated fibers, such as those of PE/PET, PE/PP or the like, or mono-fibers,
such as those of PE, PP, PET or the like.
Crimping is performed by means of a crimper upon manufacturing of filaments
and number of crimp is increased by pre-heating calender or hot air process. For
example, crimping condition of the TOW is that number of crimp per 1 inch of one
continuous filament is in a range of 5 to 40 or in a range of 15 to 30, and after
opening, crimp modulus of elasticity of one continuous filament is greater than
or equal to 70%.
Number of crimp is based on JIS L-1015 and crimp modulus of elasticity is
based on JIS L-1074. In case of the filament of a fineness less than 5.5 dtex,
an initial load of 0.49 mN is applied in pulling direction, and in case of the
filament of a fineness greater than or equal to 5.5 dtex, an initial load of 0.98
mN is applied in pulling direction. Number of crimp referred to is number of threads
(peaks) per 1 inch (25 mm) when the initial load is applied.
On the other hand, the crimp modulus of elasticity is expressed by:
{(b-c)/(b-a)}×100(%)
wherein a is a length of filament when the initial load is applied, b is
a length when the crimp is stretched by applying a tension force of 4.9 mN per
1.1 dtex for 30 seconds, and c is a length as applied the initial load again after
2 minutes from releasing of the tension force.
When opened TOW is used for a surface layer of an absorbent article, the continuous
filaments are preferably treated to be hydrophilic with a hydrophilic agent being
applied to their surfaces or kneaded in the resin. It is also preferred that the
continuous filaments contain inorganic filler for whitening, such as titanium oxide
or the like, in the content of 0.5 to 10% by weight. By whitening process, the
continuous filaments may easily hide menstrual blood or the like absorbed in an
absorbent layer of an absorbent article from external view. The individual continuous
filaments may have a circular or modified cross-section.
In the opening process
1, TOW
2A is transported toward right in
the drawing by means of a transporting roll group composed of rolls
3,
4a,
4b,
5a,
5b,
6a,
6b,
7,
8 and
9. Between the paired rolls
4a and
4b and the paired rolls
5a and
5b, sliding
plates
11 and
12 as sliding bodies are provided. The sliding plates
11 and
12 are placed in opposition relative to the TOW
2A
and with offset in transporting direction of the TOW. As shown in FIG. 2, the front
edges
11a and
12a of respective sliding plates
11
and
12 extend in straight in width direction of the TOW. In the shown embodiment,
the front edges
11a and
12a are chamfered to have a
wedge-shaped section, but may be otherwise chamfered to have a curved section or
the like. Of course, it is possible not to chamfer the front edges
11a
and
12a. The front edges
11a and
12a
so extend as to permit sliding of the entire TOW
2A.
It is also possible that the front edges
11a and
12a
extend
in a curved (arcuate) shape or in a corrugated shape. In case of curved (arcuate)
shape, the center portion of respective front edges
11a and
12a
is recessed away from the TOW
2A. In case of corrugated shape, convex
shape projecting toward the TOW
2A and concave shape recessed away from
the TOW
2A are repeated in the width direction of the TOW.
On the other hand, as shown in FIG. 3, the front edge
11a of the
sliding plate
11 and the front edge
12a of the sliding plate
12 are preferably located to penetrate into a transporting path of the TOW
2A. Here, the transporting path of the TOW
2A is meant to indicate
a path extending in straight between the paired rolls
4a and
4b
and the paired rolls
5a and
5b. In FIG. 3, the
transporting path extends vertically. Furthermore, it is preferred to provide an
overlapping amount (overhanging amount) 0 between the sliding plates
11
and
12 (as expressed by a distance between the front edges
11a
and
12a in the horizontal direction of FIG.
3). Also,
in order to increase friction force in sliding between the front edges
11a
and
12a and the TOW
2A, it is preferred to set tilt angle
θ for the sliding plates
11 and
12 relative to a line perpendicular
to transporting path of the TOW
2A (horizontal line in the shown case).
Particularly, the tilt angle θ is preferably set to orient the front edges
11a and
12a upwardly. However, it is also possible
to set the tilt angle θ to orient the front edges
11a and
12a
downwardly for absorbing increased magnitude of friction force in sliding associating
with increasing of overlapping amount O.
When the TOW
2A is transported while sliding on the front edges
11a
and
12a of the sliding plates
11 and
12, at first,
one side of the TOW
2A receives the resistance from the sliding plate
11.
By this sliding resistance, a shifting force in the transporting direction acts
on individual continuous filaments stacked in thickness direction of the TOW
2A
to separate adjacent filaments from each other. More specifically, when separated
by application of the shifting force, the individual filaments, which have been
firmly fitted with each other in a condition with matching phase of crimp before
opening the TOW, are brought into contact with each other in a condition with shifting
phase of crimp. Accordingly, repulsive forces f and f are caused between adjacent
filaments due to contact between peaks and bottoms of crimps, so that the filaments
are uniformly spread in the width direction of the TOW.
Next, the other side of the TOW
2A receives the resistance from the
sliding plate
12. Accordingly, a shifting force in the transporting direction
is also applied to individual continuous filaments stacked in thickness direction
of the TOW
2A, for further opening. Thus, the TOW
2A is further spread
to have a width W. In the drawings, TOW opened to have the width W is indicated
at
2B. Hereinafter, for sake of clarity, the TOW indicated at
2B
is referred to as fibrous layer
2B.
In order to make opening by means of the sliding plates
11 and
12
effective, it is preferred to apply a tension to the continuous filaments between
the paired rolls
4a and
4b and the paired rolls
5a
and
5b. The peripheral speeds of the paired rolls
4a
and
4b and the peripheral speeds of the paired rolls
5a
and
5b may be the same. However, for appropriately applying tension,
it is preferred to make the peripheral speeds of the paired rolls
5a
and
5b higher than the peripheral speeds of the paired rolls
4a and
4b.
It is preferred that the sliding plates
11 and
12 are so mounted
on a not shown supporting member so to permit adjustment of individual penetration
amounts of the sliding plates
11 and
12 into the transporting path
of the TOW
2A (i.e., the overlapping amount O of the sliding plates
11
and
12) and also permit adjustment of individual tilt angles θ of
the sliding plates
11 and
12. In the opening method and opening apparatus
using the sliding plates
11 and
12, it becomes possible to adapt
to variation of material and fineness of continuous filament, basis weight of the
TOW
2A and so forth only by adjusting the penetration amounts (overlapping
amount O) and/or the tilt angles θ of the sliding plates
11 and
12.
By effecting adjustment from time to time, moreover, quality of the opened fibrous
layer
2B can be made stable.
While the adjusting operation can be performed manually, it is also possible
to automatically adjust the penetration amounts and the tilt angles θ of
the sliding plates
11 and
12 as in the embodiment shown in FIGS.
1 and 2.
In the embodiment shown in FIGS. 1 and 2, in order to achieve automatic adjustment,
detecting means
15 for detecting the width W of the fibrous layer
2B
of the opened continuous filaments is provided between the paired rolls
6a
and
6b and the roll
7.
The detecting means
15 includes a pair of CCD cameras
16 for confronting
two side edges of the fibrous layer
2B and a background plate
17
located at opposite side of the cameras
16 relative to the fibrous layer
2B for confronting the fibrous layer
2B. Since the continuous filaments
are white or semi-transparent, the background plate
17 may be provided a
color of good contrast in color to the continuous filaments, such as black, dark
green and so forth.
An image picked up by the camera
16 is processed by an image processing
portion
21 to detect two side edges of the fibrous layer
2B as boundary
lines. The position information of the boundary lines detected by the image processing
portion
21 is applied to a control portion
22 which takes CPU as
primary component. In the control portion
22, the position information of
the boundary lines are compared with a preliminarily set threshold value and a
correction value is calculated.
On the other hand, on supporting portions of the sliding plates
11 and
12, adjusting means (adjusting actuators)
24a and
24b
which can adjust a moving amount in horizontal direction and the tilt angles
θ of the sliding plates
11 and
12, are provided. The adjusting
means
24a and
24b have stepping motors for varying
penetration amounts of the sliding plates
11 and
12 into the transporting
path of the TOW
2A and stepping motors for varying the tilt angles θ
of the sliding plates
11 and
12.
The correction value calculated by the control portion
22 is applied to
a driver
23 which controls the adjusting means
24a and
24b.
The driver
23 operates the adjusting means
24a and
24b
on the basis of the correction value.
In the automatic adjustment, the optimal width of the fibrous layer
2B
after opening are preliminarily predicted depending upon material and fineness
of the continuous filaments and basis weight of the supplied TOW
2A, and
information relating to the predicted optimal width is input to the control portion
22. On the basis of the input value, the threshold value is determined.
When the width W of the fibrous layer
2B after opening is smaller than the
predicted optimal width, adjustment by the adjusting means
24a and
24b is performed to make the overlapping amount O and/or the tilt
angles θ greater. Conversely, when the width W of the fibrous layer
2B
after opening is greater than the predicted optimal width, adjustment by the adjusting
means
24a and
24b is performed to make the overlapping
amount O and/or the title angles θ smaller.
By performing automatic adjustment in response to material and fineness of the
continuous filaments and basis weight of the supplied TOW
2A, optimal opening
can be performed constantly and whereby quality of fibrous layer
2B opened
becomes stable. Also, when the TOW
2A is varied in material, basis weight
or the like, the overlapping amount O and the tilt angles of the sliding plates
11 and
12 can be automatically adapted by only varying setting value
input to the control portion
22.
In the embodiment shown in FIG. 1, a production process
30 of a surface
layer of an absorbent article is continuously arranged following to the opening
process
1.
In the production process
30 of the surface layer, a liquid permeable,
heat-fusible base
31 is transported through transporting rolls
32,
33 and
34. The base
31 may be a point bonded non-woven fabric,
a through-air bonded non-woven fabric, a spun bonded non-woven fabric, an air-laid
non-woven fabric, a span laced non-woven fabric or the like. In such case, use
can be made of core-sheath type or side-by-side type conjugated fibers treated
to be hydrophilic, such as those of PE/PP, PE/PET or PP/PP. In an alternative,
as the base
31, it is also possible to use a film formed of thermoplastic
synthetic resin, a laminate sheet of a film and a non-woven fabric, or the like.
Furthermore, a foam film formed with a large number of holes by applying vacuum
pressure to molten/semi-molten resin on a screen drum, or a film formed with holes
by elongation strain by hot needles may also be used.
When the non-woven fabric is used as the base
31, it is preferably corrugated
to have wrinkles repeated along transporting direction. The corrugated non-woven
fabric can be easily contracted in the transporting direction (Y direction).
On the other hand, the elastic members
35 are supplied through another
path other than the path of the base
31. Each elastic member
35 may
be made of synthetic rubber or natural rubber and takes form in string or strip.
For providing sufficient contracting force for the base
31 in the Y direction,
when strain amount in stretching direction is provided in a range of 5 to 50%,
preferred contractive tension of one elastic member
35 is in a range of
1.86 to 7.64 mN.
The elastic members
35 are transported by the transporting rolls
36,
37,
38,
39 and
41. The peripheral speed of the transporting
roll
37 is higher than that of the paired transporting rolls
36.
The peripheral speed of the transporting roll
38 is higher than that of
the transporting roll
37. The peripheral speed of the transporting roll
39 is higher than that of the transporting roll
38. The peripheral
speed of the paired transporting rolls
41 is higher than that of the transporting
roll
39. Between the paired transporting rolls
36 and the paired
transporting rolls
41, thus, the elastic members
35 are given a tensile
strain in range of 5 to 50%. Thereafter, the elastic members
35 are fixed
to the base
31 in a condition where the foregoing tensile strain is applied.
Here, the individual elastic member
35 in the form of string or strip are
spaced apart from each other in a direction perpendicular to the transporting direction
by a constant interval to extend in parallel, and are fixed to the base
31
by a hot melt adhesive or the like.
The fibrous layer
2B opened in the opening process
1 is widened
(spread in the width direction) by a widening guide
42 to have a uniform
bulkiness. Subsequently, by the paired transporting rolls
33, the fibrous
layer
2B thus opened and widened is supplied to the surface of the base
31 having the elastic members
35 fixed on the back face thereof.
Between the paired transporting rolls
33 and the paired transporting
rolls
34, the stack of the fibrous layer
2B, the base
31 and
the elastic members
35 is clamped between welding rolls
44 and
45,
one of which is provided with emboss for forming fixing lines
52 of a pattern
shown in FIG.
7. After passing through the welding rolls
44 and
45,
the fibrous layer
2B is partially fixed to the base
31 at the fixing
lines
52 as shown in FIG.
7. At this time, the fixing method is heat
seal or sonic seal.
On the downstream side of the paired transporting rolls
34, stretching
force on the elastic members
35 is released. Then, by elastic contracting
force of the elastic members
35, the base
31 is uniformly contracted
in the Y direction to make a distance between adjacent fixing lines
52 smaller
to form a large number of loop portions
51 from the fibrous layer
2B.
Thus, a surface layer
50 is produced.
FIG. 7 is a plan view of the surface layer
50, and FIG. 8 is a section
of an absorbent article employing the surface layer
50.
The fixing lines
52 formed by the welding rolls
44 and
45
are formed at a constant pitch in the Y direction. More specifically, the fixing
lines
52 are arranged in staggered manner between rows adjacent in the X
direction. Therefore, as a result of contraction of the base
31 in the Y
direction by elastic contracting force of the elastic members
35, the loop
portions
51 are formed respectively between adjacent fixing lines
52
to have relatively large bulkiness. Furthermore, the loop portions
51 can
behave independently of each other.
FIG. 6 shows a sanitary napkin
60 as one example of the absorbent article.
As shown in FIG. 8, the sanitary napkin
60 has a structure, in which a liquid
absorbing layer
62 is laid on a liquid impermeable backing sheet
61
and a liquid permeable surface sheet
63 is laid over the liquid absorbing
layer
62.
The surface layer
50 formed through the manufacturing process set forth
above is located at the center region or the entire region of a liquid receiving
surface of the sanitary napkin
60, for example. The surface sheet
63
and the base
31 are partially fixed by a hot melt adhesive.
In the surface layer
50, the loop portions
51 are formed between
respectively adjacent fixing lines
52. The continuous filaments of the fibrous
layer
2B forming the loop portions
51 have freedom in the X direction
and Y direction and have restoring ability against pressure in compression direction.
Accordingly, the surface layer
50 may flexibly conform to the skin of a
wearer to reduce irritative feeling on the skin. On the other hand, menstrual blood
or the like applied to the loop portions
51 flows along the continuous filaments
of the loop portions
51 to reach the base
31 to be absorbed in the
liquid absorbing layer
62 through the base
31 and the surface sheet
63.
Next, FIGS. 4 and 5 are explanatory illustrations showing other embodiments
of the present invention.
In the opening process shown in FIG. 4, a plurality of sliding plates
11
and a plurality of sliding plates
12 are provided. By providing the plurality
of sliding plates
11 and the plurality of sliding plates
12, which
are opposed to each other relative to the TOW
2A, opening of the TOW
2A
can be performed more effectively.
In the embodiment shown in FIG. 5, the fibrous layer
2B opened by the
sliding
plates
11 and
12 is transported by transporting rolls
71,
72,
73,
74,
75, peripheral speeds of which are higher
at downstream side roll than the upstream side roll to apply a tension force on
the fibrous layer
2B. Subsequently, the tension force is released by transporting
rolls
76 and
77, peripheral speeds of which are lower at the down
stream side roll than the upstream roll.
In this embodiment, the fibrous layer
2B opened by the sliding plates
11
and
12 is further processed by applying and releasing tension force, to
further progress opening.
On the other hand, in the manufacturing process
30 of the surface layer
shown in FIG. 1, elastically contractive base
31 may be employed without
using the elastic member
35, or in the alternative, heat shrinking material
may be used for the base
31. In this case, after the fibrous layer
2B
is fixed at the fixing lines
52 in FIG. 7, the base
31 is contracted
by heat shrink for forming the loop portions
51.
As set forth above, with the present invention, the TOW of the continuous filaments
can be effectively opened and quality of the fibrous layer after opening becomes
stable. Also, it becomes possible to easily adapt for variation of basis weight
of the TOW or variation of material or fineness of the continuous filaments.
For manufacturing the absorbent article, such as sanitary napkin, various way
has been taken, and the absorbent article may be formed in various structure and
configuration. For instance, the absorbent articles and manufacturing process have
been disclosed in commonly owned co-pending U.S. patent application entitled "ABSORBENT
ARTICLE EMPLOYING SURFACE LAYER WITH CONTINUOUS FILAMENT AND MANUFACTURING PROCESS
THEREOF"(claiming priority based on Japanese Patent Application No. 2000-265467)
and also in commonly owned co-pending U.S. patent application entitled "ABSORBENT
ARTICLE HAVING FIBROUS LAYER ON SURFACE"(claiming priority based on Japanese Patent
Application No. 2000-265476). The disclosure of the above-identified commonly owned
co-pending U.S. patent applications are herein incorporated by reference.
Although the present invention has been illustrated and described with respect
to exemplary embodiment thereof, it should be understood by those skilled in the
art that the foregoing and various other changes, omission and additions may be
made therein and thereto, without departing from the spirit and scope of the present
invention. Therefore, the present invention should not be understood as limited
to the specific embodiment set out above but to include all possible embodiments
which can be embodied within a scope encompassed and equivalent thereof with respect
to the feature set out in the appended claims.
*
