EP0329829A2 - Device for applying glue or a similar product to a surface - Google Patents

Abstract

The device 100 serves for applying very small amounts of a glue or a similar product to the surface of a web-shaped substrate 1 passing by below the device 100. The application occurs by means of a plurality of slot nozzles 35 which are arranged next to one another, but separated from one another, and are supplied by a separate glue pump in each case. …<IMAGE>…

Description

The invention relates to a device of the type corresponding to the preamble of claim 1.

The starting point of the invention has been problems which occurred during the production of hygiene articles. This should be understood to mean articles such as diaper pants for babies, diaper pads, sanitary napkins, medical pads, surgical pads and the like, which are used to collect liquid separated from the body and on one side a liquid-impermeable, very flexible film of low thickness, for example made of polypropylene of 12 to 15 My ( Micrometers) to which a flat suction pad made of cellulose or a suitable plastic material is glued, which in turn is covered by a fleece.

The suction pad consists of a loose material in the manner of a short-fiber cotton, which must be fixed on the film so that it stays in place and does not slip when handling the article. For this reason, the suction pad is glued to the film.

The difficulty with this bonding stems from the fact that the film to which the glue has to be applied is very mechanically and thermally sensitive. For this reason, it has already been attempted to glue with cold glue. Cold glue, however, is an aqueous dispersion and there is therefore a risk that problems with possible moisture inclusion will occur with absolutely tight end packaging. The alternative is the use of hot-melt adhesive, but with which it is difficult to evenly distribute a small application quantity over the application width, which is generally in the range from 200 to 800 mm. If, as is assumed in the preamble, an order is made with a uniform application nozzle that extends across the width of the order, considerable effort must be expended to allow the glue to emerge evenly from the slot nozzle in the small amount. A reasonably uniform distribution requires, in particular, a low viscosity of the hot-melt adhesive, which was therefore applied at temperatures of 110 to 140 ° C. However, the uniformity was unsatisfactory. The high temperature of the hot glue applied and the application quantity of 2 to 4 g / m 2, which so far could not be undercut, resulted in the film being strongly deformed and the back of the hygiene article produced having an irregularly wavy relief.

The process is also practiced of applying individual narrow glue traces placed next to one another on the film at intervals. However, these traces of glue are also clearly evident on the back of the film and are also disadvantageous in that form channels between the glue traces, in which the suction pad is not connected to the film and, as experience has shown, can escape through the liquid.

Based on the problem described, the object of the invention is to design a generic device such that very small application quantities per unit area can be applied particularly uniformly to a leading substrate across its width.

This object is achieved by the invention reproduced in claim 1.

So it is no longer working with a slot nozzle that is continuous over the application width, in which it is very difficult to obtain uniform discharge quantities over the entire length, but instead a number of narrower slot nozzles are placed side by side, so that the width of the individual slot nozzle is correspondingly smaller . With an application width of approximately 240 mm, for example, eight individual slot nozzles, each 30 mm wide, can be present. Within such a narrow single slot nozzle, the uniform distribution across the width is not yet a major problem. The essential point, however, is that these individual slot nozzles each have their own glue pump and are not supplied by a common glue pump via a distributor head. This measure ensures that the same amount of glue is always allocated to each individual slot nozzle and the distribution over the entire width of the application is correspondingly uniform. If namely, a slot nozzle should be hydrodynamically preferred because, for example, due to manufacturing tolerances, it has a slightly larger slot width, or because of Flow resistance of the channels up to the slot nozzle is somewhat lower, so this slot nozzle will only release exactly the amount of the order assigned by the pump assigned to it. If there is such a hydrodynamically preferred area in the case of a slot nozzle which extends over the entire application width, the application quantity preferably emerges at this point and the pressure drops sharply towards the sides, as a result of which different application quantities per unit area cannot be avoided.

With regard to the hygiene articles mentioned, in which the glue has to be applied to a sensitive film, there are two important advantages. The tests have shown that the application quantity can be reduced to an amount of 0.2 g / m². Quite apart from the saving of glue, this has the effect that the heat capacity of the applied glue is very low and thus the thermal load on the substrate, i.e. the film remains low. Another factor works in the same direction, namely that in order to even out the application, it is no longer necessary to ensure that the glue has as low a viscosity as possible with a continuous slot nozzle. The application is also even when applied with a slightly higher viscosity. This means that the temperature of the glue can be reduced to values around 65 ° C without loss of uniformity, which also reduces the stress on the film.

The gluing of the film for the hygiene articles mentioned is the starting point and preferred example of application of the invention, but it is understood that the device can also be used for substrates other than those mentioned Foils can be used, especially for even application of very small amounts of glue. Glue is also only the preferred application of the invention and other liquid to highly viscous application agents are by no means excluded.

According to claim 2, the separate glue pumps assigned to the individual slit nozzles can be provided in the form of a multiple pump, in which, if it is designed as a gear pump, a corresponding number of planetary counter gears, for example, working against a common central wheel, produce cleanly separated flow rates.

The adjacent individual slot nozzles can be formed in the manner set out in claim 3.

The two "surfaces" are formed, for example, by an end face of a nozzle plate provided on the device, in which the feed channels open, and a clamping strip extending in front of it, which clamp the slotted plate between them. The feed channels open into the areas of the slotted plate that remain free between the webs, so that the glue is channeled through the back of the slotted plate and the webs, and the individual glue flows are only combined immediately before the exit point, so that on the one hand there is a uniform coverage of the application width , a transfer of glue from a slot nozzle into the neighboring one is practically prevented.

It is advisable to point the webs towards the exit point, so that the individual glue streams can easily merge.

In practice, the nozzle plate is an integral part of the device, as a result of which a distribution of the outlet openings of the feed channels in the end face of the nozzle plate is predetermined at certain distances in the direction of the application width. Now it may happen that the order width has to be changed. To accomplish this task, the embodiment shown in claim 5 in the form of the intermediate plate is used, with the aid of which the exit points of the feed channels opening into the individual slot nozzles can be pulled apart or pushed together. In such a case, the slotted plate and the intermediate plate are replaced, and it is therefore possible to work with eight slit nozzles of, for example, 35 mm wide instead of eight slit nozzles each 30 mm in width, without any assembly work other than unscrewing the terminal strip and replacing the slit plate and the intermediate plate are required.

The spreading of the outlet mouths of the feed channels can be brought about in the manner set out in claim 6.

• Fig. 1 zeigt eine Seitenansicht der Vorrichtung;
• Fig. 2 zeigt eine Ansicht gemäß Fig. 1 von links;
• Fig. 3 zeigt eine vergrößerte Ansicht des linken un­teren Teils von Fig. 1, teilweise im Schnitt;
• Fig. 4 zeigt den unteren Teil von Fig. 3 mit Zwischen­platte;
• Fig. 5 zeigt eine Ansicht des Schlitzblechs;
• Fig. 6 zeigt eine vergrößerte Wiedergabe des in Fig. 5 mit VI bezeichneten, mit einem strichpunktierten Kreis um­gebenen Bereichs;
• Fig. 7 zeigt eine Ansicht der Zwischenplatte, gemäß Fig. 4 von links;
• Fig. 8 ist ein Schnitt nach der Linie VIII-VIII in Fig. 7 in vergrößertem Maßstab;
• Fig. 9 ist eine Ansicht der Zwischenplatte von oben;
• Fig. 10 ist eine Ansicht der Rückseite der Zwischen­platte nach Fig. 7.

In the drawing, an embodiment of the invention is shown.

• Fig. 1 shows a side view of the device;
• FIG. 2 shows a view according to FIG. 1 from the left;
• Fig. 3 shows an enlarged view of the lower left part of Fig. 1, partly in section;
• Fig. 4 shows the lower part of Fig. 3 with intermediate plate;
• Fig. 5 shows a view of the slotted plate;
• FIG. 6 shows an enlarged representation of the region designated by VI in FIG. 5 and surrounded by a chain-dotted circle;
• Fig. 7 shows a view of the intermediate plate, according to Fig. 4 from the left;
• Fig. 8 is a section along the line VIII-VIII in Fig. 7 on an enlarged scale;
• Fig. 9 is a top view of the intermediate plate;
• 10 is a rear view of the intermediate plate of FIG. 7.

The device 100 shown in FIGS. 1 and 2 is used to provide the film web 1 with a very thin layer of hot-melt adhesive over an application width 2 (FIG. 2) evenly. In the exemplary embodiment, the film web 1 consists of polypropylene of 15 my thickness and is guided past the exit point 3 of the hot-melt adhesive in the manner shown in FIG. 1 with a slight wrap angle and a slight longitudinal tension. The film web 1 is therefore not supported at the exit point 3.

The device 100 comprises an application head, designated as a whole by 4, and this in turn comprises an application block 5 with inner channels, which are shown in detail in FIG. 3. The application block 5 is held by two side walls 6, which are connected by a cross plate 7, which in turn is fastened in a suitable manner above the film web 1 in the machine frame.

A drive motor 8 is fastened to the cross plate 7 and drives an eightfold gear pump 10 mounted on the order block 5 via an angular gear 9. The eightfold gear pump 10 comprises eight individual gear pumps which generate eight metered glue flows which are independent of one another and which are passed through inner channels into the application block 5. The liquid glue brought up from a melting device, not shown, passes through one Filter 11 and enters the order block 5 at the channel 12 and at the mouth 13 into the eightfold gear pump 10, which dispenses the glue in eight mutually independent streams into eight vertical channels 14 according to FIG. 3, across the width the web are distributed in the order block 5 attached. An order valve 15 is assigned to each channel 14 and is connected to the channel 14 via a transverse channel 17. In addition, each channel 14 is assigned a return valve 16 arranged above the application valve 15, which is connected to the channel 14 via a transverse channel 18. A glue return 20 is also connected to the return valve 16 via a transverse channel 19. The valves 15, 16 have the same design in terms of their hydrodynamic resistance and are pneumatically controlled. The air supply lines are labeled 21 and 22, respectively. The design is such that the valves 15, 16 are always actuated alternately, ie when the application valve 15 closes, the return valve 16 opens and leaves the glue conveyed in by the pump 10 in the channel 14 instead of via the transverse channel 17 to the application valve 15 via the cross channel 18 to the return valve 16, which is then open and passes the glue into the glue return 20. In this way, a glue flow of constant pressure can be maintained in the channel 14 regardless of the actuation of the application valve 15, in which no pressure surges occur due to the closing of the application valve 15.

As can be seen from FIG. 2, eight valve pairs 15, 16 are provided next to one another in accordance with the number of channels 14.

According to FIG. 3, a nozzle plate 23 is screwed under the application block 5 and the application valve 15, which has a vertical or essentially end face 24 which extends substantially perpendicular to the substrate and into which eight glue channels 25, which start from the respective outlet mouth of the application valves 15, open . A slotted plate 30 is arranged in front of the end face 24, the shape of which can be seen in FIG. 5 and which is screwed against the end face 24 by a clamping strip 26 with a flat rear face 27.

The end face 24 and the rear face 27 have lower edges 28 and 29, respectively, which are at the same height.

The slotted plate 30 is made of brass or corrosion-resistant steel and has a thickness of 0.3 mm. It covers the end face 24. On the underside, a rectangular cutout 31 is formed, which extends over the application width 2 (FIG. 2) and which, in the exemplary embodiment, has eight webs 32 protruding into the cutout 31 in the embodiment by seven comb teeth which are arranged at equal intervals Chambers 33 is divided. The webs 32 are about 1 mm wide and tapered at the front. The tip lies at a short distance 34 (FIG. 6), for example 1 mm, above the lower edge 28 of the end face 24 when the slotted plate 30 is mounted in the manner shown in FIG. 3.

The chambers 33 are closed on three sides, but open at the bottom and, together with the surfaces 24 and 27, form downwardly opening, separate slot nozzles 35 (FIG. 2).

As can be seen from Fig. 2, the valves 15, 16 are arranged close to each other. Their width is essentially fixed, so that a certain transverse distance between the glue channels 25 cannot be undershot. If the Order width 2 is dimensioned so that the division of the glue channels 25 coincides with the division of the slot nozzles 35, the glue channels 25 can open directly into the slot nozzles 35 formed, as shown in Fig. 3.

If, however, the division of the slot nozzles 35 does not match the division of the channels 25 and the slot nozzles are narrower than the distances between the application valves 15 (see FIG. 2), an adaptation by an intermediate plate 40 is required, which in the installed state in FIG. 4 and in different views in FIGS. 7 to 10.

The intermediate plate 40 has the same outline as the end face 24 or the slotted plate 30. On the front side shown in FIG. 7, in the longitudinal direction of the intermediate plate 40 extending but separate expansion grooves 36 are provided, the length of the width of the chambers 33 of the slotted plate 30 correspond. In the assembled state according to FIG. 4, the webs 32 each extend at the locations of the interruptions between successive spreading grooves 36. The middle six spreading grooves 36 have through bores 37 in the middle, which pass through to the rear side of the intermediate plate 40 shown in FIG. 10 . From the mouths of the through bores 37 on the back, angled channels 38, formed as grooves, lead to the points 39, which lie opposite the mouths of the glue channels 25 in the end face 24 of the nozzle plate 23. The locations 39 have the distance from one another corresponding to the glue channels 25, the through bores 37 have the distance given by the slot nozzles 35. In the through holes 37 'leading to the two outer spreading grooves 36', the associated channel 38 'is arranged for spatial reasons on the front side of the intermediate plate 40 shown in FIG. 7. The openings of the through bores 37 in the spreading grooves 36 are denoted by 41 in FIG. 9.

By interposing the intermediate plate 40 according to FIG. 4, it is thus possible to change from the division of the application valves 15 or glue channels 25 specified in a specific device 100 to another division, for example to a narrower division with a smaller application width 2, as in FIG Fig. 2 shown, but also to a further division, if necessary.

To change the order width, all that is required is to unscrew the terminal block 26 'and to replace the intermediate plate 40 and the slotted plate 30.

Claims (6)

1. Device for the flat application of glue or the like on a leading substrate, in particular on the heat-sensitive moisture protection film of hygiene articles,
with a storage container for the glue,
with an applicator head with a slit nozzle arrangement provided transversely to the direction of advance of the substrate for applying the glue to the substrate,
with a pump arrangement for conveying the glue from the storage container to the application head
and with a conveyor, by means of which the substrate can be passed directly under the slot nozzle arrangement,
characterized,
that the slit nozzle arrangement comprises a plurality of individual slit nozzles (35) which are arranged directly next to one another and are seen from each other in the flow direction of the glue until just before the exit point (3) of the glue, and the pump arrangement for each slit nozzle (35) has its own metering glue pump. 2. Device according to claim 1, characterized in that the glue pumps are given by a multiple pump (10). 3. Apparatus according to claim 1 or 2, characterized in that the slot nozzles (35) through one between two flat surfaces (24, 27), of which the glue channels (25) fed by the individual glue pumps open out and at the same height located lower edges (28, 29) delimit the exit point (3), clamped slotted plate (30) is formed which, between the chambers (33) corresponding to the individual slit nozzles (35), has narrow webs (32) protruding like comb teeth, which, in the direction of flow seen the glue, just before the exit point (3) end. 4. The device according to claim 3, characterized in that the webs (32) are tapered towards the exit point (3). 5. Apparatus according to claim 3 or 4, characterized in that the glue channels (25) in a perpendicular to the forward direction of the substrate (1) surface (24) of the application head (4) open and an intermediate plate (40) adjacent to the surface (24) ) is provided, on the other side of which the slotted plate (30) rests and has the through-channels, the openings (41) leading into the individual slit nozzles (35) formed by the slotted plate (30) have a different distance from one another than that on the other side located junctions (39). 6. The device according to claim 5, characterized in that the through channels perpendicular to the intermediate plate (40) have through bores (37,37 ') and the transverse adjustment by transverse grooves on at least one side of the intermediate plate (40) provided transverse grooves (38, 38 ') takes place.

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