EP2613891B1 - Method and adhesive applicator for the contactless application of a multiplicity of discrete spots of adhesive, distributed over a surface area, permanently to a substrate - Google Patents

Description

FIELD OF THE INVENTION

The invention relates to a method and adhesive application device for non-contact application of a plurality of distributed on a surface, non-contiguous adhesive dots on a substrate for permanent retention with the features of the preamble of claim 7. Accordingly, is provided with respect to the adhesive application device, a plurality of on a surface distributed, non-contiguous adhesive dots on a substrate to permanent local whereabouts apply without contact. For this purpose, a rotatable applicator head is used. The applicator head has means distributed on its radial (outer) surface for transferring adhesive dots to a substrate. The substrate is generally planar, in particular web-shaped and is passed in a suitable manner on the rotating applicator head.

TECHNOLOGICAL BACKGROUND

When applying adhesive to a substrate, such as a filter cloth or a membrane film, it is important in some applications to keep as much of the substrate surface as possible, ie, free of adhesive. For this purpose, it is possible to apply strongly stretched and therefore thin adhesive threads or dots to the substrate and to use a rotary head for non-contact adhesive application (US Pat. WO 2007/036338 ), from which the invention proceeds.

In this known method, the order pattern can be adhered to only as precisely as this non-contact centrifugal technology allows, namely in dependence on the rotational speed of the rotary head, the adhesive pressure pending there, the adhesive temperature, the ambient temperature and the type of adhesive. The ambient temperature remains in most cases a not completely controllable factor, since working in temperature-controlled production areas is usually too expensive.

A non-generic application method for patterning adhesive dots that works according to the contact principle is known as pocket technology. In this case, the means for transferring the adhesive dots consist of small-caliber "cups", ie recesses in the roller surface of the applicator roll whose mostly circular base, depth and cup contour can be freely specified and produced, for example, by etching. The wells are depending on the desired surface density and distribution according to a desired Surface pattern introduced into the roll surface. The procedure is such that the wells are filled with adhesive by means of a leak roll or other means known from printing technology and the remaining surface of the applicator roll is kept free of the adhesive. Then, the filled with adhesive cups can be brought by rotation of the roller surface of the applicator roll with surface contact or at least with line contact to a substrate or a transfer roller and the adhesive transferred to it. In this method, it is very important to pay attention to the surface temperature of the applicator roll and the adhesive temperature, because otherwise an excessive thread formation after transfer of the adhesive point from the roll surface to the substrate is the result. In other words, the volume of adhesive introduced in the individual wells can not be transferred to the substrate fast enough and, as a rule, not completely enough so that an adhesive thread is formed between the wells on the applicator roll and the glue dots on the substrate , Such adhesive threads tear in an undefined manner and the thread cooling leads to the point of glue on the substrate not having sufficiently uniform contours. In addition, adhesive residues can remain in the wells and gradually add in operation and they make the applicator roll thus exchange or at least require cleaning.

Another contact application method for hot melt adhesive on a surface is from the DE 2125387 A1 known. The job is carried out via a plurality of nozzles in a flat application plate, the supply holes are opened via needle-like, resiliently projecting from the plate valve tappet when the application plate is pressed flat on the substrate. This method is suitable for the batchwise hot melt application (batch operation). After the back of the application plate from the substrate and closing the valves form between the substrate and the outstanding from the order plate needle-like valve creases adhesive threads, which by means of a pivotable cutting bracket with a heatable cutting blade in Furthermore, thread-free application systems are known, with which melted thermoplastic coating materials can be transferred from a coating head to a substrate. For this purpose, known from the screen printing technique, a printing pattern exhibiting Siebähnlicher cylinder is known on which a to be provided with a printing pattern web-shaped or arcuate substrate in physical conditioning is guided under the pressure of a counter-roller linearly along. An elongated, parallel to the application roller arranged feed chamber, for coating materials, has a nozzle slot which rests against the inner surface of the perforated cylinder jacket in the region of the contact line of the counter-pressure roller. The coating material is expressed from the nozzle slot by the cylinder jacket perforation in the physical contact of cylinder and substrate on the substrate. Such, non-generic transfer methods are exemplified in DE 19905317 A1 and DE 4020420 A1 known. It has proven to be difficult to transfer as many and / or small-area as possible adhesive dots in this way on a substrate. The EP 1 160 016 A2 discloses an adhesive applicator apparatus for applying a plurality of discontinuous adhesive dots distributed on a surface to a substrate for permanent retention therein, comprising a rotary applicator head having means for distributing the adhesive dots for transferring the adhesive dots to the substrate displaceable relative to the rotary applicator head wherein the transfer means are an order pattern forming openings in a roll surface of an applicator roll forming roll shell, which are acted upon on the inside of the roll shell with the adhesive.

PRESENTATION OF THE INVENTION

The invention is based on the problem of improving a generic adhesive application method and apparatus for surface patterns of adhesive dots in such a way that thread-like adhesive structures on the treated substrate as far as possible are eliminated. To solve this problem, an adhesive application method with the features of claim 1 and an adhesive application device with the features of claim 7 is proposed. Accordingly, the method provides that a rotating applicator head carrying an aperture pattern on its circumference is displaced with lateral (radial) spacing from and relative to the surface of the substrate to be permanently provided with the pattern in an application direction. The adhesive is expelled to form lenticular bulges from the apertures of the applicator head in the region of a line or strip-like distance gap formed between the substrate and the applicator head. The adhesive bulges are brought into contact with the substrate in the region of the gap, without that da-Der Adhesive is expelled to form lenticular bulges from the apertures of the applicator head in the region of a line or strip-like gap formed between the substrate and the applicator head. The adhesive bulges are brought into contact with the substrate in the area of the gap without the application head touching the substrate. The adhesive protrusions are peeled off the respective openings while adhering to the substrate and forming adhesive dots on the substrate.

With regard to a generic adhesive application device, the invention provides that the transfer means for the (small) adhesive volumes are a plurality of a desired order pattern forming openings in a roll surface of an applicator roll forming roller shell, which are acted upon on the inside of the roll shell with the adhesive. Between the roller surface and the substrate, a clearance gap or nip is provided and dimensioned so that the adhesive can be pressed out to form lens-like bulges from the perforations of the application head in the region of the distance gap formed linearly or in strips between the substrate and the application head. The adhesive protrusions contact the substrate in the area where the gap is located, without the applicator head touching the substrate. The adhesive protrusions are peelable from the respective apertures while adhering to the substrate and forming adhesive dots on the substrate.

By virtue of the invention, the adhesive viscosity and thus its thread forming behavior can be controlled better and less dependent on the ambient temperature. It was recognized that a temperature gradient in the adhesive could be utilized between the gun and the substrate. Even very temperature-sensitive sheet or web-shaped substrates, such as films made of PE, can be permanently provided with a surface pattern of adhesive dots.

Typical opening (breakthrough) cross sections are in the order of a few mm to a few microns, preferably between 2 and 0.01 mm and more preferably between 1 and 0.1 mm. As a rule, drill holes and thus cylindrical openings are sufficient. However, the opening cross sections may also have other cross-sectional shapes, e.g. also be made by lasers. Within the transfer roller can be provided elongated, approximately parallel to the roll axis Klebstoffzuführkammern which always supply only a limited number of adhesive transfer means / openings with adhesive, while the remaining openings are kept free of adhesive. Such a chamber preferably extends along the line of transmission between the surface of the applicator roll and the adhesive accepting substrate. As a result, the tendency to thread formation is further reduced. The inner surface of the roll mantle is guided along the open exit surface of the chamber for adhesive substantially sealingly along the chamber wall surrounding the exit surface, so that a shearing action is exerted on the adhesive on the entrance side of the apertures.

In order to minimize the negative consequences of a certain thread formation, which can not be completely prevented even with the device according to the invention as a rule, a thread-like or blade-shaped adhesive thread separating element may be located behind the transfer nip, as seen in the substrate movement direction Be provided. The arrangement of this element is very particularly preferably parallel to the axis of rotation of the applicator head, but may also have a direction parallel to the roller axis direction component to fulfill its function. In this way it is possible to selectively separate the approximately forming adhesive thread at an early stage after the beginning of its formation. This ensures that the still comparatively low-viscosity adhesive can pull back from the separation point to the transmitted to the substrate main mass of the respective point of adhesive. For this purpose, the surface tension of the drop of adhesive usually suffices. The located on the other side of the separating element of the Due to the early separation of the adhesive thread and its surface tension and viscosity, forming adhesive thread has the possibility of retracting to the transfer means on the surface of the applicator roll. In the case of transmission means formed by perforations in a roll shell, the adhesive originating from the one thread part can be kept sufficiently viscous to be used further in the subsequent transfer step, ie a rotation of the transfer roller by less than 360 ° for the next point of adhesive. Such an adhesive-thread-separating member may also be successfully used together with adhesive applicator rollers for adhesive dots by means of the above-described cups, as well as those applications in which products other than adhesives such as granular plastics are produced. The above solution idea is therefore of independent inventive importance.

To facilitate retraction of the separated adhesive filaments to their respective starting point, the adhesive filament separator can be brought to an appropriate temperature. In particular, it is possible to use an electrical resistance thread or wire which is kept at the desired temperature by electric heating. As a result, the adhesive threads can be melted through, so that the proportion of mechanical separation effect is significantly reduced to completely. The distance of the adhesive-separating element from the nip between the transfer roller and the substrate can be varied depending on the application. Preferred Nipabstände be up to 10cm, preferably up to 1cm and more preferably up to 0.1cm.

The above-mentioned and the claimed components to be used according to the invention described in the exemplary embodiments are not subject to special conditions of size, shape, material selection and technical design, so that the selection criteria known in the field of application can be used without restriction

Further details, features and advantages of the subject matter of the invention will become apparent from the subclaims, as well as from the following description and the accompanying drawings, in which - by way of example - an embodiment of an applicator for adhesive dots is shown. Also, individual features of the claims or of the embodiments may be combined with other features of other claims and embodiments.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1

eine schematische Darstellung der Klebstoffauftragvorrichtung in Stirnseitenansicht;

Fig. 2

dieselbe Vorrichtung in einer Seitenansicht der Auftragswalze (Ansicht A-A gemäß Figur 1);

Fig. 3

einen Querschnitt durch die Vorrichtung entlang der Schnittlinie III-III gemäß Fig. 2;

Fig.4

eine alternative Ausführung einer Klebstoffauftragsvorrichtung in einer Seitenansicht entsprechend Fig. 2 sowie

Fig. 5

eine Detaildarstellung des Abziehens eines Klebstoffvolumens aus einem Klebstoffauftragskopf.

In the drawing show

Fig. 1

a schematic representation of the adhesive application device in front view;

Fig. 2

the same device in a side view of the applicator roll (view AA according to FIG. 1 );

Fig. 3

a cross section through the device along the section line III-III according to Fig. 2 ;

Figure 4

an alternative embodiment of an adhesive applicator in a side view accordingly Fig. 2 such as

Fig. 5

a detailed view of the removal of an adhesive volume from an adhesive applicator head.

DETAILED DESCRIPTION OF EMBODIMENTS

How out FIG. 1 can be seen, a rotatable about its longitudinal axis, circular cylindrical in cross-section applicator roll 1 is provided distributed over its circumference with a plurality of drilled openings 2 in a roll shell 1A. One Web-shaped substrate 3 is guided at a small distance below the roll surface along this. The peripheral speed of the roller surface can be synchronized with the linear speed of the substrate and optimized as desired with a view to the thread formation. As a result of the adhesive which is conveyed inside the applicator roll and which is under suitable pressure, in this way adhesive dots 4 are formed on the substrate surface in accordance with the distribution pattern of the adhesive-transferring perforations on the roll surface. Details are out FIG. 5 seen. Between the outside mouths of the openings 2 on the roll surface and the generated adhesive dots, adhesive threads 4A can form. These are severed by means of an adhesive thread separating element 6, for example in the form of a hot thread at a location close to the nip between the roll surface and substrate web, preferably by melting and / or mechanically. The hot thread is stretched parallel to the roll axis and over its length but at least across the width of the substrate web 3 and supplied with electrical voltage at 6A in order to maintain a desired thread temperature and to be able to introduce sufficient heat into the separation point.

How out FIG. 2 can be seen, an adhesive supply 7A lead to the applicator roll 1 to an adhesive chamber 7 in the roll interior. One there, how out FIG. 3 can be seen, held stationary adhesive chamber housing 8 extends at least over the application width of the applicator roll 1 and seals against the inner surface of the roll shell 1A. An adhesive feed slot 7B leads from the elongated adhesive chamber 7 to the inner surface of the roll mantle 1A, thus feeding a series of apertures 2 during the time that this row passes the adhesive feed slot. Accordingly, the apertures 2 of this series give only in this period of time for a specific adhesive point 4 amount of adhesive.

After severing the then pulls between the substrate 3 at the glue point 4 and the openings 2 forming adhesive thread 4A pulls the one half of the thread to its opening 2 and the other half of the thread back to their glue point 4.

According to preferred embodiments, the adhesive separator 6 may be self-cleaning or one provided with a cleaning unit 10. For example, a self-cleaning adhesive separator may vaporize or chemically decompose adhesive filament residues to clean the separator at its active length, all the time, or at certain intervals.

FIG. 4 shows an embodiment of the invention with cleaning unit 10. In this embodiment, an elongated adhesive-separating element in the form of, in particular electrically, heatable wire continuously around two pulleys 10A, 10B and 10C, at least one of which is provided with a rotary drive 10A, constantly or temporarily moved in the longitudinal direction. As a result, the zone active for the thread-separating step comes out of the same and can, for example, pass through a scraper 10D or another cleaning unit that cleans the surface of the adhesive-separating element 6. Possible adhesive residues can be collected in a collecting element 10E. The heating and temperature control of the adhesive separating element 6 can by means of one of the deflection rollers 10A and 10B by thermal or electrical contact, as shown in the left in FIG. 4 indicated, via a power supply 6A done. Instead of a peripheral adhesive-separating element 6, it is also possible to unwind a corresponding thread-like element from a coil and roll up on another or reversing the adhesive-separating element to lead through the separation points.

In order to interrupt the area-distributed permanent application of non-contiguous adhesive dots on the substrate in certain seen in the direction of order intervals, the distance gap between the gun and the substrate, under continued relative movement of the same in Order direction, be enlarged. As a result, the adhesive lens in the nip area can no longer get the necessary contact with the substrate.

LIST OF REFERENCE NUMBERS

1

applicator roll

1A

roll shell

1B

roll axis

2

perforations

3

substratum

4

adhesive points

4A

adhesive threads

4B

bulge

6

Adhesive-thread-separating element

6A

electrical power supply

7

Klebstoffverteilkammer

7A

Klebstoffzuführleitung

7B

Adhesive feed slot

8th

Adhesive chamber housing

9

Substrate Auflagstisch

10

cleaning unit

10A

drive

10B

deflection roll

10C

deflection roll

10D

scraper

10E

collecting element

11

application direction

12

moving unit

13

Distance changing unit

G

spacing gap

L

longitudinal extension

Claims (16)

1. A method for the application of a multiplicity of discrete spots of adhesive distributed over a surface area onto a substrate to remain permanently thereon, characterized in that
   a rotating applicator head bearing a perforation pattern on the periphery thereof is displaced at a radial distance from and relative to the surface of the substrate (3) that is to be furnished permanently with the pattern, wherein the substrate (3) is displaced in an application direction (11) relative to the rotating applicator head,
   the adhesive is pressed out of the perforations (2) in the applicator head in the area of a linear or strip-like gap (9) formed between the substrate (3) and the applicator head, creating lenticular adhesive bulges (4B),
   the adhesive bulges (4B) are brought into contact with the substrate (3) in the area of the gap (9), wherein the applicator head does not touch the substrate (3), and
   the adhesive bulges (4B) are detached from the respective perforations (2), adhering to the substrate (3) and forming adhesive spots (4) on the substrate (3).
2. The method according to claim 1, characterized in that adhesive filaments forming between the substrate and the rotating applicator head behind the transfer clearance are severed at a predetermined distance behind the transfer clearance by means of an adhesive thread separating element extending along the applicator head, in particular by melting.
3. The method according to claim 2, characterized in that the separation is effected by electrical resistance heating.
4. The method according to either of claims 2 or 3, characterized in that the elongated adhesive filament separating element is moved continuously or intermittently in a first or a second direction of the longitudinal extension thereof.
5. The method according to any one of claims 2 to 4, characterized in that the adhesive filament separating element is cleaned continuously or periodically.
6. The method according to any one of claims 1 to 5, characterized in that the permanent application of discrete adhesive spots over a distribution area on the substrate is interrupted at defined intervals when viewed in the direction of application by enlarging the gap between the applicator head and the substrate while the relative movement of the same continues in the direction of application.
7. An adhesive application apparatus for contactless application of a multiplicity of discrete spots of adhesive, distributed over a surface onto a substrate to remain permanently thereon, comprising a rotating applicator head having means disposed for the distribution of the adhesive spots for transferring the adhesive spots to the substrate, which is displaceable relative to the rotating applicator head, characterized in that
   the transfer means consist of perforations (2) that create an application pattern in an outer roller shell (1A) of a rolling surface of an application roller (1), which perforations are chargeable with the adhesive on the inside of the outer roller shell (1A), and that
   a gap (G) or clearance is provided between the roller surface and the substrate (3) and dimensioned in such manner that the adhesive can be expressed out of the perforations (2) in the applicator head forming lenticular bulges (4B) in the area of the linear or strip-like gap (G) created between the substrate (3) and the applicator head, and the adhesive bulges (4B) come into contact with the substrate (3) in the area of the gap (G), while the applicator head does not touch the substrate (3), and
   the bulges (4B) are detachable from the respective perforations (2) while still adhering to the substrate (3) and forming adhesive spots (4) on the substrate (3) of the respective openings.
8. An adhesive application device according to claim 7, characterized in that the largest cross-sectional dimension of the perforations (2), which may in particular be holes having different geometries or also slits, is between 2 mm and 0.01 mm and particularly preferably between 1 and 0.1 mm.
9. The adhesive application device according to either of claims 7 or 8, characterized in that an adhesive distribution chamber (7) lies flush against the inner surface of the roller shell (1A) and the aperture edges thereof are sealed.
10. The adhesive application device according to any one of claims 7 to 9, characterized in that a filamentous or blade-shaped adhesive thread separating element (6) is arranged with a directional component parallel to the roller axis (1B) at a point behind the transfer clearance in the direction of application.
11. The adhesive application device according to claim 10, characterized in that the adhesive thread separating element (6) is positioned at a distance of up to 10 cm, preferably up to 1 cm, and particularly preferably up to 0.1 cm behind the transfer clearance.
12. The adhesive application device according to either of claims 10 or 11, characterized in that the adhesive thread separating element (6) is heatable, and in particular is adjustable to generate sufficient heating power to melt through adhesive filaments.
13. The adhesive application device according to any one of claims 10 to 12, characterized in that a movement unit (12) is provided for continuously or intermittently moving the elongated adhesive thread separating element (6) in a first or a second direction of the longitudinal extension thereof.
14. The adhesive application device according to any one of claims 10 to 13, characterized in that a cleaning unit (10) is provided for continuous or periodic cleaning of the adhesive thread separating element.
15. The adhesive application device according to any one of claims 7 to 14, characterized in that a distance adjustment unit (13) is provided for selectively increasing the gap (G) between the applicator head and the substrate in defined distances when viewed in the direction of application direction (11) while the relative movement between the substrate and is the rotating applicator head continues.
16. Use of an adhesive application device according to any one of claims 7 to 15, characterized in that an application roller furnished with shell perforations and with an adhesive supply in the interior thereof is used for producing a permanent surface pattern of adhesive geometries on a substrate (3).

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