U.S. patent application number 09/982346 was filed with the patent office on 2002-07-18 for device and method for applying a liquid to sheet-shaped materials.
Invention is credited to Kanamuru, Fuminori, Takagi, Hiroyuki, Todo, Hiroshi.
Application Number | 20020092865 09/982346 |
Document ID | / |
Family ID | 18831969 |
Filed Date | 2002-07-18 |
United States Patent
Application |
20020092865 |
Kind Code |
A1 |
Takagi, Hiroyuki ; et
al. |
July 18, 2002 |
Device and method for applying a liquid to sheet-shaped
materials
Abstract
[Problems to be Solved] The present invention provides a method
and a device for applying a plurality of zigzag patterns on a
sheet-shaped substrate with a liquid such as a hot-melt adhesive,
which can (1) prevent fluctuation in the amplitude of the coated
pattern, (2) maintain good stability of the coated pattern, (3)
improve the cutoff of the liquid when stopping the supply of
liquid, and (4) improve the intermittence of the coated pattern.
[Means of Solving the Problem] A device for applying a liquid such
as an adhesive 31 on a substrate 14 such as long sheet-shaped
materials traveling at high speed, said device consisting of a
valve mechanism 15 which starts and stops the supply of a liquid,
at least two liquid-discharge ports 16 which discharge a liquid fed
through the valve mechanism, two seam air-discharge ports 10g
provided at both sides of the liquid-discharge port 16 the
direction of which intersects the travel direction of the
substrate, two supplementary air-discharge ports 10k provided very
close to each liquid-discharge port and at both sides of the
liquid-discharge port, and at least a partition wall 17 positioned
between adjacent liquid-discharge ports that protrudes downward by
a prescribed length.
Inventors: |
Takagi, Hiroyuki;
(Kagawa-Ken, JP) ; Todo, Hiroshi; (Narashino-Shi,
JP) ; Kanamuru, Fuminori; (Sapporo-Shi, JP) |
Correspondence
Address: |
WOOD, HERRON & EVANS, L.L.P.
2700 Carew Tower
441 Vine St.
Cincinnati
OH
45202
US
|
Family ID: |
18831969 |
Appl. No.: |
09/982346 |
Filed: |
October 17, 2001 |
Current U.S.
Class: |
222/94 ;
118/313 |
Current CPC
Class: |
B05C 5/0237 20130101;
B05C 5/0279 20130101; B05B 7/0861 20130101 |
Class at
Publication: |
222/94 ;
118/313 |
International
Class: |
B65D 035/22 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 20, 2000 |
JP |
P2000-360350 |
Claims
1. Device for applying a liquid on sheet-shaped materials, which is
a device for applying a liquid such as an adhesive on a substrate
such as long sheet-shaped materials traveling at high speed,
characterized in that said device consists of (a) a valve mechanism
which can start and stop the feeding of a liquid, (b) at least two
liquid-discharge ports which discharge the liquid fed through the
valve mechanism and which are adjacent to the direction of crossing
the travel direction of the substrate, (c) two seam air discharge
ports arranged on both sides of each liquid-discharge port in the
direction of crossing the travel direction of the substrate, (d)
two supplementary air discharge ports arranged adjacent to said
liquid discharge port on both sides in the travel direction of the
substrate, and (e) a partition wall positioned between the two
adjacent liquid discharge ports and protruding downward by a
prescribed length.
2. Device for applying a liquid on sheet-shaped materials as
described in claim 2 [sic]; characterized in that the partition
wall is also installed at the end of the coating device which is
adjacent to the liquid-discharge port positioned at the end of the
coating device in the direction of crossing the travel direction of
the substrate.
3. Method for applying a liquid on sheet-shaped materials, which is
a method for applying a liquid, such as an adhesive, on long
sheet-shaped materials traveling at high speed, using a coating
device equipped with a valve mechanism to start and stop feeding a
liquid, at least two liquid-discharge ports which discharge the
liquid fed through the valve mechanism, and a partition wall
positioned between the two adjacent liquid discharge ports and
protruding downward by a prescribed length, said method comprising
the following steps: (a) discharging a liquid from the
liquid-discharge port of the coating device provided in noncontact
with the sheet-shaped substrate, (b) discharging seam air from the
seam air discharge ports provided in the direction of crossing the
travel direction of the substrate and on both sides of the liquid
discharge port onto the bead-form liquid discharged from the
liquid-discharge port which swings the bead-form liquid in the
direction of crossing the travel direction of the sheet-shaped
substrate, (c) attaching the swung bead-form liquid to the surface
of the traveling sheet-shaped substrate, and (d) steps of (a)-(c)
are carried out for each liquid-discharge port of the coating
device while supplementary air is being discharged from the
supplementary air-discharge ports provided near both sides in the
travel direction of the substrate to coat a liquid on the
sheet-shaped substrate.
Description
[0001] The present invention pertains to a device and a method for
applying a liquid such as a hot-melt adhesive to sheet-shaped
substrates such as PE (polyethylene) backing sheets (e.g., paper
diapers, etc.), flat-plane substrates such as nonwoven fabrics, or
yarn-, string-, or belt-shaped substrates, which are used by
discharging said liquid form the liquid discharge port of a coating
device placed in noncontact with the substrate material, then
attaching said material to another substrate.
[0002] [Conventional Techniques]
[0003] Many spray apparatuses have been used for discharging
adhesives from the adhesive-discharge ports of a coating device
provided in noncontact with a PE (polyethylene) backing sheet
(e.g., paper diapers, etc.), flat substrates such as nonwoven
fabrics, or yarn-, string-, or belt-like substrates. The spray
modes of the spray apparatuses include atomization spray, spiral
spray, slot spray, controlled weave, etc.
[0004] [Problems to be Solved by the Invention]
[0005] In the aforementioned spray apparatuses, however, at the
time of hot-melt coating, there are often problems such as
scattering of the hot melt, unwanted dribbling of the hot melt,
overspraying, etc. There may also be problems with the hot melt
pattern coated on a substrate, including poor stability of the
coating pattern and poor intermittence. In particular, the
distribution of the hot melt in a pattern coated by the hot melt
discharged from a discharge nozzle may be uneven, which is
problematic. Because of such problems, the spray performance of any
hot melt selected had to be excellent.
[0006] The present invention was carried out in view of such
problems and its object is to provide a device and a method for
applying liquids on substrates with the following improvements; in
the invention device and method, a liquid (that is, a hot-melt
adhesive) is discharged onto a plane sheet-shaped substrate from a
liquid discharge port and applied in a zigzag pattern on the
substrate, and the device and method can prevent fluctuation in the
amplitude of the zigzag coating pattern of the liquid, improve the
stability of the coating pattern of the liquid, and when the supply
of liquid is terminated, the liquid is completely cut off, which
improves the intermittence of the coating pattern.
[0007] [An Approach to Solving the Problems]
[0008] In order to attain the above-mentioned object, the present
invention comprises the following:
[0009] (1) A device for coating a liquid, such as an adhesive, on a
substrate such as long sheet-shaped materials traveling at high
speed, characterized in that said device consists of
[0010] (a) a valve mechanism which can start and stop the feeding
of a liquid,
[0011] (b) at least two liquid-discharge ports which discharge the
liquid fed through the valve mechanism and which are adjacent to
the direction of crossing the travel direction of the
substrate,
[0012] (c) two seam air-discharge ports arranged on both sides of
each liquid-discharge port in the direction of crossing the travel
direction of the substrate,
[0013] (d) two supplementary air discharge ports arranged adjacent
to said liquid discharge port on both sides in the travel direction
of the substrate, and
[0014] (e) a partition wall positioned between the two adjacent
liquid discharge ports and protruding downward by a prescribed
length.
[0015] (2) In the device described above in (1), a partition wall
is also installed at the end of the coating device which is
proximate to the liquid-discharge port positioned at the end of the
coating device in the direction of crossing the travel direction of
the substrate.
[0016] (3) A method for coating a liquid, such as an adhesive, on
long sheet-shaped materials traveling at high speed using a coating
device consisting of a valve mechanism to start and stop feeding a
liquid, at least two liquid-discharge ports which discharge the
liquid fed through the valve mechanism, and a partition wall
positioned between the two adjacent liquid discharge ports
protruding downward by a prescribed length, said method comprising
the following steps:
[0017] (a) discharging a liquid from the liquid-discharge port of
the coating device provided in noncontact with the sheet-shaped
substrate,
[0018] (b) discharging seam air from the seam air discharge ports
provided in the direction of crossing the travel direction of the
substrate and on both sides of the liquid discharge port onto the
bead-form liquid discharged from the liquid-discharge port which
swings the bead-form liquid in the direction of crossing the travel
direction of the sheet-shaped substrate,
[0019] (c) attaching the swung bead-form liquid to the surface of
the traveling sheet-shaped substrate, and
[0020] (d) steps of (a)-(c) are carried out for each
liquid-discharge port of the coating device while supplementary air
is being discharged from the supplementary air-discharge ports
provided near both sides in the travel direction of the substrate
to coat a liquid on the sheet-shaped substrate.
[0021] [Action]
[0022] The case of applying a liquid in the form of a hot-melt
adhesive will now be explained. By operating the valve mechanism of
a coating device for starting and stopping the supply of a liquid
such as an adhesive, the liquid (such as a hot-melt adhesive)
supplied from a known adhesive feed device as a liquid-feed device
is discharged in the form of a continuous bead onto a sheet-shaped
substrate, such as a backing sheet for disposable diapers, which is
traveling at high speed, from the adhesive-discharge port as a
liquid-discharge port arranged in noncontact with the backing
sheet. When seam air (also called "pattern air") is discharged from
the seam air-discharge port (also called "pattern air-discharge
port") arranged on both sides of the adhesive-discharge port in the
direction of crossing the travel direction of the substrate, the
seam air contacts the adhesive bead and swings said bead.
[0023] This occurs in such a way that the bead is swung in the seam
air discharge direction with the adhesive-discharge port at the
center, that is, in a wave shape (zigzag or seam shape) in the
direction of crossing the travel direction of the substrate. The
swung adhesive beads are affixed to the surface of the traveling
backing sheet in a direction of crossing the travel direction of
the sheet, that is, with pre-established amplitude in the right and
left directions. Therefore the position relationship of the seam
air-discharge nozzle with respect to the adhesive-discharge port
should be established in terms of the direction of crossing the
traveling backing sheet.
[0024] Coating can be carried out while supplementary air
(auxiliary air) is being discharged from the supplementary
discharge port provided near the adhesive-discharge port of the
coating device near both sides of the traveling direction of the
backing sheet. In this way, cleaning of the adhesive-discharge port
can be carried out and at the same time irregular fluctuation of
the bead-shaped adhesive being swung in a wave shape by the seam
air discharged from the adhesive-discharge port can be prevented
and regular swinging in the right and left directions while
intersecting the travel direction of the back sheet will take
place.
[0025] That is, fluctuation in the pitch of the wavy pattern in the
travel direction of the sheet can be suppressed and, at the same
time, when the supply of adhesive is terminated, the hanging down
of the adhesive that reaches the cut part of the sheet which
remained near the adhesive-discharge port, the so-called phenomenon
of "cutting off the adhesive", can be prevented, thereby the cutoff
of the adhesive is improved, thus the intermittence can be
improved.
[0026] When the position of the supplementary air-discharge ports
at nozzles on both sides of the adhesive-discharge port is such
that, when the distance from the adhesive-discharge port is less
than the adaptability position, the amplitude of the wavy pattern
becomes broader, the wavy pattern becomes unstable, and the
swinging becomes disordered. Therefore the selection of a suitable
distance from the adhesive-discharge port to the supplementary
air-discharge port is important, and when this is done the
stability of the coated pattern can be improved. In this
connection, when supplementary air is supplied, the amplitude
(width of the swing) can be made broader than when it is not
supplied.
[0027] The stability of the wavy pattern of the adhesive beads is
important when an adhesive is to be coated on a backing sheet,
especially when the substrate is a plane surface (a flat board),
e.g., the backing sheet of a paper diaper, being coated with a
prescribed pattern using an adhesive, and then it is laminated on
another substrate such as a nonwoven fabric; in the lamination, it
is important that there is no uneven coating on the backing sheet
and that the necessary pattern is formed in a minimum area by
coating with an adhesive, and at the same time, if the pattern of
the adhesive overlaps with another pattern, then the coating
thickness of the adhesive will be too thick, thus causing the user
to feel uncomfortable and also wasting the adhesive.
[0028] In the present invention, at least two adhesive-discharge
ports as liquid-discharge ports are arranged in the direction of
crossing the travel direction, therefore at least two wavy (zigzag,
seam-like) patterns are formed in parallel on the surface of the
backing sheet in the travel direction of said sheet. In this case,
in the present invention, a partition wall is installed between an
adhesive-discharge port and another adhesive-discharge port,
thereby any interference by the seam air and supplementary seam air
of adjacent adhesive-discharge ports to each wavy adhesive bead
formed by the seam air and the adhesive discharged from each
adhesive-discharge port, can be prevented. Thus the disordering of
the wavy adhesive beads formed after the adhesive is discharged
from each adhesive-discharge port can be prevented, thus the wavy
pattern of adhesive beads discharged from each adhesive-discharge
port can be stabilized considerably. And interference between the
adjacent wavy patterns can be prevented also.
[0029] The cleaning provided by the supplementary air avoids the
phenomenon which consists of the adhesion of fine dust floating in
the air that comes from the backing sheet or the nonwoven fabric
substrate, on the adhesive-discharge port, solidification over
time, obstruction of a stable coating process, and making the
discharge of adhesive difficult. In addition, the partition wall
can protect the adhesive-discharge port, supplementary
air-discharge port, etc., of the body of the coating device when
other objects impact the coating device.
[0030] In the present invention, even if the substrate is a
yarn-shaped or a string-shaped material, the swung adhesive beads
can be affixed in the direction of crossing the travel direction of
the substrate. The adhesive affixed on the surface of a yarn-shaped
or a string-shaped material flows as a viscous fluid after adhesion
and may hang down and around the lower part of the
string-shaped.substrate and become smooth, thereby the whole
circumference of the string-shaped substrate can be coated.
[0031] When the partition wall installed in the coating device is
installed not only between the adhesive-discharge ports but also at
the end of a coating device near the adhesive-discharge port
positioned at the end of a coating device in the direction of
crossing the travel direction of the substrate, then the spread of
the adhesive beads to the outside of the end of the coating device
can be prevented, therefore the ends (turnup end) of the outermost
adhesive beads of the many stripes of a wavy pattern to be coated
on the surface of the backing sheet substrate can be put on a
straight line in the travel direction. In the above, the case of a
hot-melt adhesive was described for the liquid to be coated,
however, the invention can be applied to coating with any liquid in
the form of a liquid coating material.
[0032] [Mode of Carrying Out the Invention]
[0033] Next, an embodiment of the present invention will be
described with the use of figures. In the present embodiment, one
coating device can simultaneously form four coating patterns of an
adhesive, however, this is not intended to limit the invention in
any way. And a hot-melt adhesive is used as a coating liquid,
however, other liquid coating materials can also be used. All the
figures shown an embodiment of the present invention. FIG. 1 is a
front view of the coating device, FIG. 2 is a vertical sectional
view of FIG. 1, FIG. 3 is a diagram of the nozzle block seen from
side A in FIG. 2, FIG. 4 is a diagram of the nozzle block, seen
from side B in FIG. 2, FIG. 5 is a sectional view along C-C of FIG.
4, FIG. 6 is a bottom view of the nozzle block, FIG. 7 is a
schematic diagram of the manner of application of an adhesive, and
FIG. 8 is a plan view of the coating condition (pattern) of
adhesive on a backing sheet.
[0034] In the Figures, 1 is a coating device with a valve mechanism
15 which can be opened or closed by operating air 30. That is, 2 is
a gun body with a cylinder 2a provided in the upper part of said
gun body 2, and a piston 5 which moves up and down is installed
inside the cylinder 2a. A piston cover 3 is attached by a plurality
of bolts 4 to the upper part of the gun body 2. 25 is a spring, and
said spring forces the piston 5 downward at all times.
[0035] The piston 5 is connected to a valve lot [Isn't this really
a (valve) disk or plate attached to a valve stem or rod? ----Tr.
Ed.] 6, which extends through sealing members 7 and 8 installed in
the small diameter section inside the gun body 2 and into the
liquid chamber 9. An adapter 12 is attached by a plurality of bolts
13 to the lower part of the gun body 2. Inside the adapter 12, an
adhesive through-hole 12b is formed at the valve seat 12a which can
communicate with the liquid chamber 9 and an adhesive through-hole
12b is formed at the downstream side of the valve seat 12a. The
lower part of the adhesive through-hole 12b is bent in the shape of
the letter "L" and opens at the flat section 12c of the adapter 12.
The valve lot 6 cooperates with the valve seat 12a of the adapter
12 to form a valve mechanism 15 which is kept closed at all times
by the action of the spring 25.
[0036] 10 indicates a nozzle block, and 11 is a nozzle holding
plate. The nozzle block 10 and the nozzle holding plate 11 are
stacked and attached with a plurality of bolts 19 to the flat
section 12c of the adapter 12. The configuration of the nozzle
block 10 is shown in detail in FIGS. 3-6. The nozzle block 10 is
provided with attaching holes 10a for the bolts 19. On side A, a
triangular groove 10b is formed for the adhesive 31, and at the
bottom of triangular groove 10b, four holes provided at
approximately equal intervals extend from the triangular groove 10b
in the horizontal direction to midway inside the block 10, and from
the ends of the through-holes, separate through-holes extend at
approximately equal intervals in the downward direction.
[0037] And the leading end of each through-hole opens at the
underside of the projecting part 10c formed as a protrusion from
the underside of the nozzle block 10. The opening constitutes and
adhesive-discharge port 16. That is, the four adhesive-discharge
ports 16 are provided at approximately equal intervals in the width
direction (that is, the direction which is perpendicular to the
travel direction of the sheet 14 which is a substrate) of the
nozzle block 10. The aforesaid adhesive through-hole 12b of the
aforesaid adapter 12 opens into the apex of the triangular groove
10b.
[0038] 10d is a through-hole for air 32 that extends through the
nozzle block 10, and said two through-holes 10d are provided which
communicate with an air groove 10e on side B which extends to the
lower part of the nozzle block 10. The air groove 10e communicates
with horizontally long air groove 10f which extends in the width
direction of the nozzle block on its underside, and further from
the lower part of the air groove 10f, a plurality (eight) of seam
air holes 10m are provided which extend horizontally to
approximately midway inside the nozzle block 10. And at the lower
part of the nozzle block 10, the two adjacent air holes 10m in the
width direction of the nozzle block 10 are connected to the seam
air (which is also called pattern air) discharge ports 10g which
open on both sides (that is, both sides in the direction which is
perpendicular to the travel direction of the sheet substrate with
the adhesive-discharge port 16 as the center) of the
adhesive-discharge port 16.
[0039] Then the seam air discharge port 10g has an opening which
slants with respect to the vertical axial line of the
adhesive-discharge port 16 at the same angle as the angle of
inclination of the projecting part 10c at the end of the installed
projecting part. The diameter of the seam air discharge port is
0.3-1.0 mm. When the opening is made in such a way that angle
.theta. to the adhesive-discharge port 16 is 10-20 degrees, which
is the same as the angle of inclination, good results can be
obtained. And when the seam air-discharge port 10g is formed at the
end where the projection part 10c was formed, the boring process
can be easily accomplished.
[0040] On the other hand, from the horizontally long air groove
10f, two supplementary air grooves 10h which extend downward
communicate with air groove 10f, and below it a horizontally thin
supplementary air groove 10i, which communicates with supplementary
air groove 10h, is formed, and furthermore air groove 10i
communicates with one supplementary air-discharge port 10k which
opens below the projecting part 10c which is at the same surface as
the opening of the adhesive-discharge port 16. On the other hand,
the other supplementary air-discharge port 10k with respect to the
adhesive-discharge port 16 is connected through supplementary hole
10j which is formed by horizontal piercing and the supplementary
air hole 101 which is formed by piercing in the width direction of
the nozzle block 10 and opens below the projecting part 10c which
is at the same surface as the opening of the adhesive-discharge
port 16.
[0041] That is, each of the supplementary air-discharge ports 10k
has an opening at equal intervals at both sides of the traveling
sheet 14 (which is a substrate) with each adhesive-discharge port
16 at the center. In the present embodiment, by setting the
distance from the supplementary air-discharge port 10k to the
adhesive-discharge port 16 at 1.2 mm, good results can be
obtained.
[0042] The partition 17 between adjacent adhesive-discharge ports
16 is at the bottom 10n of the nozzle block 10 and has the same
width as that of the projecting part 10c where the
adhesive-discharge port 16 and the supplementary air discharge port
10k open, and the distance extending downward is longer than the
projecting part 10c. And in the present embodiment, also at the
bottom 10n at the end of the width direction of nozzle block 10
near the adhesive-discharge port 16 which is positioned at the end
of the width direction of the nozzle block 10, a partition 17 is
installed which has the same shape and height as those of the
partition 17 installed between the adhesive-discharge ports 16.
[0043] The nozzle block 10 with the configuration indicated above
and the nozzle holding, plate 11 are stacked with the flat part 12c
of the adapter 12 and form an integrated body, thereby the
triangular groove 10b provided on side A of the nozzle block 10
forms a space that is closed by the flat part 12c of the adapter
12, and functions as a passage for the adhesive 31. The air grooves
10e and 10f, and supplementary air grooves 10h and 10i , which are
provided on side B form grooves closed by the nozzle holding plate
11 and function as an air passage and a supplementary air passage,
respectively.
[0044] An operating air through-hole 2b which communicates with the
cylinder 2a below the piston 5 and an adhesive through-hole 2c that
communicates with the liquid chamber 9 are provided in the gun body
2. The gun body 2 and the adapter 12 are fastened to the manifold
21 by a plurality of bolts 22. Furthermore, the adapter 12 is
provided with a horizontally long groove 12d for air (seam air and
supplementary air) on the side that joins the manifold 21. And said
horizontally long groove 12d is provided with two air through-holes
12e that communicate with the two air through-holes 10d of the
nozzle block 10.
[0045] Furthermore, the manifold 21 is provided with an operating
air feed hole 21a that communicates with the operating air
through-hole 2b and an adhesive feed hole 21b that communicates
with the adhesive through-hole 2c provided in the gun body 2, and
an air feed hole 21c that communicates with the horizontally long
groove 12d provided in the adapter 12. And the operating air feed
hole 21a and the air feed hole 21c are connected via a tubular path
such as a hose to an air feed control device 23 equipped with the
function to regulate the pressure, flow rate, and temperature of
the air and the function of on-off control, these functions working
independently for each amount of air. The adhesive feed hole 21b is
also connected via a tubular path such as a hose to an adhesive
feed control device 24 also equipped with the function to control
pressure, flow rate, and temperature.
[0046] The action of the coating device 1 thus constructed will now
be explained. First, the hot-melt adhesive 31 (hereinafter referred
to simply as "adhesive") as a liquid fed from the adhesive feed
control device 24 is stored in the liquid chamber 9 after passing
through the adhesive feed hole 21b of the manifold 21 and the
adhesive through-hole 2c of the gun body 2. When the operating air
30 fed from the air feed control device 23 is fed into the cylinder
2a below the piston 5 via the operating air feed hole 21a of the
manifold 21 and the operating air through-hole 2b of the gun body
2, the piston 5 and valve lot 6 move upward against the force of
the spring 25 and the valve mechanism 15 is opened.
[0047] While the valve mechanism is open, the adhesive 31 in the
liquid chamber 9 passes through adhesive through-hole 12b of the
adapter 12 and the triangular groove 10b of the nozzle block 10,
and is discharged in the form of continuous beads from each
adhesive-discharge port 16. If air 32 fed from the air feed control
device 23 passes through the air feed hole 21c, air through-hole
12e of the adapter 12, air through-hole 10d, and air grooves 10e,
10f, and 10m, then seam air (pattern air) 33 is discharged along
the slanted wall of the projecting port 10c from the seam
air-discharge ports 10g, which are provided at both sides of each
adhesive-discharge port 16, in the direction perpendicular to the
travel direction of the sheet substrate 14.
[0048] And simultaneously with the discharge of the seam air 33,
supplementary air (auxiliary air) 34 is discharged in the direction
facing just below the supplementary air-discharge ports 10k, which
are provided at both sides of the travel direction of the sheet
(substrate) 14, through the supplementary air grooves 10h and 10i
and the supplementary air through-holes 10j and 101, which branch
from the air groove 10f of the nozzle block 10. The bead-shaped
adhesive 31 discharged from each adhesive-discharge port 16 is thus
influenced by the seam air 33 and a wave-shaped (zigzag- or
seam-shaped) swinging occurs from left to right or right to left
(side to side) (in the direction which intersects the travel
direction of the sheet 14).
[0049] At this point, the bead-shaped adhesive 31 is influenced by
the supplementary air and the irregular fluctuation of the
bead-shaped adhesive 31 which is swung from side to side by the
seam air is prevented, thus a regular amplitude is maintained in
the right-to-left direction (or left-to-right direction) which
intersects the travel direction of the sheet 14. Furthermore, by
the action of the partition wall 17 installed between adjacent
adhesive-discharge ports 16, the interference from seam air and
supplementary air which are discharged towards each
adhesive-discharge port 16 and seam air and supplementary air which
are discharged towards adjacent adhesive-discharge ports 16 can be
prevented, therefore the action of the seam air and supplementary
air of each adhesive-discharge port 16 can be carried out
independently, thus preventing any disorder of the bead-shaped
adhesive discharged from each adhesive-discharge port 16 so that
regular swinging from side to side can be suitably maintained. The
way this looks is shown in FIG. 7.
[0050] Accordingly, the amplitude in the right to left (or left to
right) direction of the bead-shaped adhesive 31 being discharged
from each adhesive-discharge port 16 can be maintained regularly,
the zigzag pattern can be thoroughly stabilized, and the
overlapping of one zigzag pattern with another zigzag pattern of
the bead-shaped adhesive formed by discharge from adjacent
adhesive-discharge ports can also be prevented. And the spread of
the zigzag pattern, which is formed by discharge from the
adhesive-discharge ports 16 positioned at the end, to the outside
of the nozzle block 10 can be prevented by the partition walls 17
which are installed at both ends in the width direction of the
nozzle block 10 of the coating device 1, and a pattern, which is as
good as the zigzag pattern formed by discharge from
adhesive-discharge ports 16 positioned at the middle section, can
be formed. Thus by the action of the partition walls 17, many
zigzag-shaped patterns can be remarkably stabilized.
[0051] And by the supplementary air, the fluctuation of the pitch
of the zigzag-shaped patterns in the travel direction of the sheet
14 can be prevented, and at the same time, when the supply of
adhesive is terminated by operation of the valve mechanism 15, the
cutoff of the adhesive will be complete, thus providing good
intermittence of the adhesive.
[0052] And the supplementary air also cleans the adhesive-discharge
ports 16, therefore the obstruction phenomenon (that is, the
sticking of suspended fine dust, which comes from the backing sheet
(substrate) 14, on the adhesive-discharge ports 16, the
accumulation of the dust over time, followed by-solidification,
which can cause the obstruction of a stable coating process or make
the discharge of adhesive difficult) can be avoided.
[0053] And the partition walls 17 can play the role of protecting
the tips of the projecting parts 10c with the supplementary air
discharge ports 10k and the adhesive-discharge ports 16.
[0054] Thus the bead-shaped adhesive 31 discharged from each
adhesive-discharge port 16 and continuously transported (the
adhesive-discharge ports 16 do not contact the sheet substrate 14)
is applied to the surface of the sheet 14 and forms a stable zigzag
pattern. The way this looks at this point is shown in FIG. 8. In
FIG. 8, four parallel zigzag patterns of adhesive (P1, P2, P3, and
P4) are applied to the sheet 14 in the travel direction of the
sheet 14. Each stripe of the pattern repeats a regular stable
amplitude in the right-to-left direction.
[0055] In the above embodiment, the bead-shaped adhesive discharged
from the adhesive-discharge ports 16 is actually a fine fibrous
(filamentous) adhesive formed by pulling the adhesive downward by
the seam air, however, the fibrous adhesive is also called a
bead-shaped adhesive in the aforesaid explanation. And in FIG. 7,
the adhesive is presented as a bead-shaped adhesive with a thick
diameter. However, in FIG. 8, the pattern coated on the sheet 14 is
presented as a linear fibrous adhesive.
[0056] Thus, the sheet 14 coated with the adhesive is laminated to
another substrate such as a nonwoven fabric at the downstream side
of the sheet 14 on a roller (not shown in the Figure). Stopping the
discharge of adhesive is accomplished by the steps of releasing the
operating air fed to the underside of the piston 5 by the operation
of the air feed control device 23, then the piston 5 and the valve
lot 6 move downward by the force of the spring 25, the valve
mechanism 15 closes, and the discharge of adhesive stops. Thus the
opening and closing operation of the valve mechanism can be used
for the intermittent coating of adhesive on, for example,
individual disposable diapers.
[0057] In the present invention, a plurality of (in the present
embodiment it is four) discharge ports for liquid such as an
adhesive are provided in a nozzle block 10 in the coating device 1,
and therefore the temperature of each discharge port 16 is equal.
So, since there is no difference in the temperature and viscosity
of the liquid being discharged from each discharge port 16, equal
amounts of liquid can be discharged from each discharge port 16,
thus ensuring good distribution of liquid per coating device.
[0058] And when the supply of liquid is terminated, the seam air
and the supplementary air also instantly cut off the liquid that
remains at the discharge port 16, therefore the scattering of the
liquid or dribbling down of the liquid can be prevented and
products with good-quality coating can be obtained.
[0059] And when a substrate coated with an adhesive is laminated to
an elastic body, a sufficient bonding strength is obtained using
only a small amount of adhesive. And a wider selection of hot-melt
adhesives also becomes possible.
Test Example
[0060] Many tests that involved applying a hot-melt adhesive on a
backing sheet 14 were repeated under the following conditions. In
all the experiments, regular zigzag patterns like those shown in
FIG. 8 were obtained. The conditions were as follows:
[0061] (1) acking sheet (substrate) material: OPP film, thickness
20 .mu.m (microns), width 300 mm, travel speed 30-300 m/min.
[0062] (2) Type of adhesive used: rubber-based hot-melt
adhesive
[0063] (3) Melting temperature of the adhesive: 160.degree. C.
[0064] (4) Distance from adhesive-discharge port to substrate: 25
mm
[0065] (5) Diameter of adhesive-discharge port: 0.5 mm
[0066] (6) Discharge pressure of the adhesive: 0.1-1.0 MPa
[0067] (7) Diameter of seam air discharge port: 0.5 mm
[0068] (8) Seam air-discharge pressure: 0.02-0.2 MPa
[0069] (9) Diameter of supplementary air-discharge port: 0.5 mm
[0070] (10) Supplementary air-discharge pressure: 0.02-0.2 MPa
[0071] (11) Pitch of adjacent adhesive-discharge ports: 5.4 mm
[0072] (12) Distance from adhesive-discharge port to seam
air-discharge port on one side: 1.0 mm
[0073] (13) Distance from adhesive-discharge port to supplementary
air-discharge port on one side: 1.2 mm
[0074] (14) Length of partition wall (projected distance from
bottom of nozzle block 10): 4.0 mm.
[0075] In the above explanation, the case of applying an adhesive
on a flat backing sheet 14 was described, however, in accordance
with the present invention, even if the substrate is yarn-shaped or
string-shaped material, swinging adhesive beads can be affixed in
the direction of crossing the traveling direction of the substrate.
For example, the adhesive applied to the surface of a roughly round
yarn-shaped material, exhibits the flow behavior of a viscous
liquid after adhesion and flows down and around the lower surface
of the yarn-shaped material, thus smoothly coating the entire
circumference of the yarn-shaped material.
[0076] And the case of applying an adhesive on the backing sheet 14
of a disposable diaper was explained, however, even in the case of
paper diapers, there are cases in which a flat, nonwoven fabric
which can be laminated to the backing sheet 14, can be used as a
substrate. The present invention can be applied no matter whether
the substrate is flat or its cross section is round.
[0077] And the case of using a hot-melt adhesive as a coating
liquid was described, however, the present invention can be applied
even when other liquid coating materials are used.
[0078] [Advantages of the Invention]
[0079] From the above explanation, it is clear that, according to
the present invention, when a flat sheet-shaped substrate is coated
with a liquid such as a hot-melt adhesive to form a plurality of
stripes in zigzag-shaped patterns, very good stability of the
patterns can be maintained, and, at the same time, good cutoff and
intermittence of the adhesive can be obtained.
BRIEF DESCRIPTION OF THE FIGURES
[0080] FIG. 1 is a front view of the coating device.
[0081] FIG. 2 is a vertical sectional view of FIG. 1.
[0082] FIG. 3 is a diagram of the nozzle block seen from side A in
FIG. 2.
[0083] FIG. 4 is a diagram of the nozzle block seen from side B in
FIG. 2
[0084] FIG. 5 is a sectional view along C-C of FIG. 4.
[0085] FIG. 6 is a bottom view of the nozzle block.
[0086] FIG. 7 is a schematic diagram of the manner of application
of an adhesive.
[0087] FIG. 8 is a top view of the coating condition (pattern) of
adhesive on a backing sheet.
DESCRIPTION OF THE SYMBOLS
[0088] (1) coating device; (2) gun body; (5) piston; (6) valve lot;
(9) liquid chamber; (10) nozzle block; (10c) projecting part (10g)
seam air (pattern air) discharge port; (10k) supplementary air
discharge port; (11) nozzle holding plate; (12) adapter; (12a)
valve seat; (14) backing sheet (substrate); (15) valve mechanism;
(16) adhesive discharge port; (17) partition wall; (21) manifold;
(23) air feed control device; (24) adhesive feed control device;
(30) operating air; (31) adhesive; (33) seam air (pattern air);
(34) supplementary air.
* * * * *