US20020092865A1

US20020092865A1 - Device and method for applying a liquid to sheet-shaped materials

Info

Publication number: US20020092865A1
Application number: US09/982,346
Authority: US
Inventors: Hiroyuki Takagi; Hiroshi Todo; Fuminori Kanamuru
Original assignee: Individual
Current assignee: Nordson Corp
Priority date: 2000-10-20
Filing date: 2001-10-17
Publication date: 2002-07-18
Also published as: JP2002126596A; JP4529060B2

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 10 g 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 10 k 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.

Description

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.

[Conventional Techniques]

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.

[Problems to be Solved by the Invention]

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.

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.

[An Approach to Solving the Problems]

In order to attain the above-mentioned object, the present invention comprises the following:

(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

(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) 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.

(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:

(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.

[Action]

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

[Mode of Carrying Out the Invention]

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.

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 2 a provided in the upper part of said gun body 2, and a piston 5 which moves up and down is installed inside the cylinder 2 a. 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.

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 12 b is formed at the valve seat 12 a which can communicate with the liquid chamber 9 and an adhesive through-hole 12 b is formed at the downstream side of the valve seat 12 a. The lower part of the adhesive through-hole 12 b is bent in the shape of the letter “L” and opens at the flat section 12 c of the adapter 12. The valve lot 6 cooperates with the valve seat 12 a of the adapter 12 to form a valve mechanism 15 which is kept closed at all times by the action of the spring 25.

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 12 c 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 10 a for the bolts 19. On side A, a triangular groove 10 b is formed for the adhesive 31, and at the bottom of triangular groove 10 b, four holes provided at approximately equal intervals extend from the triangular groove 10 b 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.

And the leading end of each through-hole opens at the underside of the projecting

part

10 c 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 12 b of the aforesaid adapter 12 opens into the apex of the triangular groove 10 b.

10 d is a through-hole for air 32 that extends through the nozzle block 10, and said two through-holes 10 d are provided which communicate with an air groove 10 e on side B which extends to the lower part of the nozzle block 10. The air groove 10 e communicates with horizontally long air groove 10 f which extends in the width direction of the nozzle block on its underside, and further from the lower part of the air groove 10 f, a plurality (eight) of seam air holes 10 m 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 10 m in the width direction of the nozzle block 10 are connected to the seam air (which is also called pattern air) discharge ports 10 g 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.

Then the seam

air discharge port

10 g 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 10 c 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 θ 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 10 g is formed at the end where the projection part 10 c was formed, the boring process can be easily accomplished.

On the other hand, from the horizontally

long air groove

10 f, two supplementary air grooves 10 h which extend downward communicate with air groove 10 f, and below it a horizontally thin supplementary air groove 10 i, which communicates with supplementary air groove 10 h, is formed, and furthermore air groove 10 i communicates with one supplementary air-discharge port 10 k which opens below the projecting part 10 c 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 10 k with respect to the adhesive-discharge port 16 is connected through supplementary hole 10 j 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 10 c which is at the same surface as the opening of the adhesive-discharge port 16.

That is, each of the supplementary air-

discharge ports

10 k 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 10 k to the adhesive-discharge port 16 at 1.2 mm, good results can be obtained.

The

partition

17 between adjacent adhesive-discharge ports 16 is at the bottom 10 n of the nozzle block 10 and has the same width as that of the projecting part 10 c where the adhesive-discharge port 16 and the supplementary air discharge port 10 k open, and the distance extending downward is longer than the projecting part 10 c. And in the present embodiment, also at the bottom 10 n 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.

The

nozzle block

10 with the configuration indicated above and the nozzle holding, plate 11 are stacked with the flat part 12 c of the adapter 12 and form an integrated body, thereby the triangular groove 10 b provided on side A of the nozzle block 10 forms a space that is closed by the flat part 12 c of the adapter 12, and functions as a passage for the adhesive 31. The

air grooves

10 e and 10 f, and

supplementary air grooves

10 h and 10 i , 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.

An operating air through-

hole

2 b which communicates with the cylinder 2 a below the piston 5 and an adhesive through-hole 2 c 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 12 d for air (seam air and supplementary air) on the side that joins the manifold 21. And said horizontally long groove 12 d is provided with two air through-holes 12 e that communicate with the two air through-holes 10 d of the nozzle block 10.

Furthermore, the manifold 21 is provided with an operating air feed hole 21 a that communicates with the operating air through-hole 2 b and an adhesive feed hole 21 b that communicates with the adhesive through-hole 2 c provided in the gun body 2, and an air feed hole 21 c that communicates with the horizontally long groove 12 d provided in the adapter 12. And the operating air feed hole 21 a and the air feed hole 21 c 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 21 b 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.

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 21 b of the manifold 21 and the adhesive through-hole 2 c of the gun body 2. When the operating air 30 fed from the air feed control device 23 is fed into the cylinder 2 a below the piston 5 via the operating air feed hole 21 a of the manifold 21 and the operating air through-hole 2 b 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.

While the valve mechanism is open, the adhesive 31 in the liquid chamber 9 passes through adhesive through-hole 12 b of the adapter 12 and the triangular groove 10 b 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 21 c, air through-hole 12 e of the adapter 12, air through-hole 10 d, and

air grooves

10 e, 10 f, and 10 m, then seam air (pattern air) 33 is discharged along the slanted wall of the projecting port 10 c from the seam air-discharge ports 10 g, 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.

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 10 k, which are provided at both sides of the travel direction of the sheet (substrate) 14, through the

supplementary air grooves

10 h and 10 i and the supplementary air through-

holes

10 j and 101, which branch from the air groove 10 f 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).

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.

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.

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.

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.

And the

partition walls

17 can play the role of protecting the tips of the projecting parts 10 c with the supplementary air discharge ports 10 k and the adhesive-discharge ports 16.

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.

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.

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.

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.

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.

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

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:

(1) acking sheet (substrate) material: OPP film, thickness 20 μm (microns), width 300 mm, travel speed 30-300 m/min.

(2) Type of adhesive used: rubber-based hot-melt adhesive

(3) Melting temperature of the adhesive: 160° C.

(4) Distance from adhesive-discharge port to substrate: 25 mm

(5) Diameter of adhesive-discharge port: 0.5 mm

(6) Discharge pressure of the adhesive: 0.1-1.0 MPa

(7) Diameter of seam air discharge port: 0.5 mm

(8) Seam air-discharge pressure: 0.02-0.2 MPa

(9) Diameter of supplementary air-discharge port: 0.5 mm

(10) Supplementary air-discharge pressure: 0.02-0.2 MPa

(11) Pitch of adjacent adhesive-discharge ports: 5.4 mm

(12) Distance from adhesive-discharge port to seam air-discharge port on one side: 1.0 mm

(13) Distance from adhesive-discharge port to supplementary air-discharge port on one side: 1.2 mm

(14) Length of partition wall (projected distance from bottom of nozzle block 10): 4.0 mm.

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.

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.

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.

[Advantages of the Invention]

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

FIG. 1 is a front view of the coating device. [0080]
FIG. 2 is a vertical sectional view of FIG. 1. [0081]
FIG. 3 is a diagram of the nozzle block seen from side A in FIG. 2. [0082]
FIG. 4 is a diagram of the nozzle block seen from side B in FIG. 2 [0083]
FIG. 5 is a sectional view along C-C of FIG. 4. [0084]
FIG. 6 is a bottom view of the nozzle block. [0085]
FIG. 7 is a schematic diagram of the manner of application of an adhesive. [0086]
FIG. 8 is a top view of the coating condition (pattern) of adhesive on a backing sheet.[0087]

DESCRIPTION OF THE SYMBOLS

([0088] 1) coating device; (2) gun body; (5) piston; (6) valve lot; (9) liquid chamber; (10) nozzle block; (10 c) projecting part (10 g) seam air (pattern air) discharge port; (10 k) supplementary air discharge port; (11) nozzle holding plate; (12) adapter; (12 a) 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.

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,

(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,

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: