APPARATUS AND METHOD FOR COATING WEBS OF MATERIAL OR SHEETS OF MATERIAL WITH HOT-MELT ADHESIVE

Abstract

An apparatus is used for coating a web of material or a sheet of material with a hot-melt adhesive (14). In order to simplify the application of hot-melt adhesive to webs of material or sheets of material, it is provided that the apparatus (10; 110) has a heated surface (25; 124) and a supply roller (16) with hot-melt adhesive (14) movable perpendicular to its axis of rotation, the web of material or the sheet of material being movable relative to the supply roller (16) while in contact with the heated surface, a pressure apparatus, which presses the supply roller (16) against the heated surface (25: 124), and a drive apparatus being provided, which drive apparatus causes the supply roller (16) to roll on the web of material or the sheet of material.

Claims

1. Apparatus for coating a web of material or a sheet of material with a hot-melt adhesive (14), characterised in that the apparatus (10; 110) has a heated surface (25; 124) and a supply roller (16) with hot-melt adhesive (14) movable perpendicular to its axis of rotation, the web of material or the sheet of material being movable relative to the supply roller (16) while in contact with the heated surface, a pressure apparatus, which presses the supply roller (16) against the heated surface (25: 124), and a drive apparatus being provided, which drive apparatus causes the supply roller (16) to roll on the web of material or the sheet of material.

2. Apparatus according to claim 1, characterised in that the heated surface is designed as a heated surface (25) of a feed roller (24) driven by a drive, which drive forms the drive apparatus, the supply roller (16) being movably guided in a linear guide.

3. Apparatus according to claim 1, characterised in that the supply roller (16) is movably driven in such a way that, in an application zone (126) in the region of the heating surface, the supply roller rolls on the web of material or the sheet of material.

4. Apparatus according to claim 3, characterised in that the heating surface is formed on a flat heating jaw (124) and is longer than the application zone (126) formed by the roll-on region of the supply roller (16).

5. Apparatus according to claim 3, characterised in that the application zone (126) is delimited by support regions (128) for the supply roller, on which regions the supply roller (16) is spatially separated from the web of material or the sheet of material.

6. Apparatus according to claim 5, characterised in that the two support regions (128) have ramps (130) as a transition to the application zone (126).

7. Apparatus according to claim 1, characterised in that the web of material or the sheet of material consists of paper.

8. Apparatus according to claim 1, characterised in that the width of the supply roller (16) for carrying out a partial coating is made narrower than the web of material or the sheet of material.

9. Apparatus according to claim 1, characterised in that the heated surface (25; 124) is designed to be wider than the supply roller (16).

10. Apparatus according to claim 1, characterised in that it has a device for bonding the coated web of material to a further layer of the material.

11. Apparatus according to claim 1, characterised in that the supply roller (16) has a bearing sleeve (18) between the hot-melt adhesive (14) and its bearing (22).

12. Method for coating a web of material or a sheet of material, characterised in that the web of material or the sheet of material is moved relative to a supply roller (16), a heat input into the web of material or the sheet of material taking place by means of a heating surface (25; 124), and the supply roller (16), which has a supply of hot-melt adhesive (14), being pressed in the direction of the heating surface (24) and melted at its pressure point, so that the hot-melt adhesive (14) is transferred across the width of the supply roller (16) to the web of material or the sheet of material.

13. Method according to claim 12, characterised in that the surface of a roller (16) is heated to form the heating surface and the correspondingly heated roller (24) is driven in order to move the web of material or the sheet of material.

14. Method according to claim 12, characterised in that, in an application zone, the supply roller (16) is rolled on the web of material or the sheet of material, the application zone being heated by a flat heating surface (124).

15. Method according to claim 12, characterised in that a web of paper (12) or a sheet of paper is processed.

16. Method according to claim 12, characterised in that the hot-melt adhesive (14) is applied only as a strip to the web of material or the sheet of material.

17. Method according to claim 16, characterised in that the strip provided with hot-melt adhesive (14) is bonded to a further layer of material in a sealing zone.

18. Hot-melt adhesive supply, characterised in that it is designed as a supply roller (16) with a solid, cylindrical hot-melt adhesive application (14) on a rotatable bearing sleeve (18).

Description

[0032] Further features, details and advantages of the invention will become apparent from the wording of the claims and from the following description of embodiments by way of the drawings, in which:

[0033] FIG. 1 is a schematic side view of a first embodiment of an apparatus for coating a material:

[0034] FIG. 2 is a schematic side view of a further embodiment of an apparatus for coating a material.

[0035] FIG. 1 shows an apparatus 10 for continuously coating a web of paper 12 with a hot-melt adhesive 14. The hot-melt adhesive 14 forms a substantial part of a supply roller 16, the hot-melt adhesive 14 being applied to a cardboard sleeve 18 as a cylindrical application.

[0036] The supply roller 16 is rotatably mounted on an axis of rotation 20 by means of ball bearings 22, the axis of rotation 20 being mounted so as to be linearly displaceable in the vertical direction in the sense of the illustration. A pressure mechanism (not shown) builds up a pressure force F which is directed downwards in the direction of a heated roller 24 in the sense of the illustration.

[0037] Between the supply roller 16 and the heated roller 24, the web of paper 12 can be moved by means of the heated roller 24 designed as a driven feed roller, the feed forces required for this movement being transferred by friction, which forces result from the pressure force of the supply roller 16. However, it is also possible to provide a separate drive and to pull the web of paper through between the then passively co-rotating rollers.

[0038] The web of paper 12 is made wider than the supply roller 16, so that only one strip of hot-melt adhesive 14 is applied to the web of paper 12, because it is usually sufficient to provide the web of paper 12 with a hot-melt adhesive application only at the points which application is to be bonded later to another layer.

[0039] In order to be able to apply the hot-melt adhesive 14 to the web of paper 12, the possibly driven heated roller 24 is correspondingly strongly heated on a heated surface 25. The temperature is set so that the hot-melt adhesive 14 on the top layer on the circumference of the supply roller 16 is heated above its melting point, the intermediate web of paper 12 reaching a corresponding temperature. The melted hot-melt adhesive 14 is thereby continuously applied as a strip to the web of paper 12 running through. The temperature of the heated roller 24 depends on the feed speed, the material properties of the web of paper or another web of material to be processed as well as its thickness, the hot-melt adhesive used of course also having an influence. It goes without saying that the melting temperature of the hot-melt adhesive must be below a temperature limit of the material above which the paper or other packaging material could suffer thermal damage.

[0040] The continuous application of hot-melt adhesive 14 to the web of paper 12 reduces the diameter of the supply roller 16 in a corresponding manner. In order to ensure permanent contact of the supply roller 16 with the heated roller 24, the aforementioned movable bearing of the supply roller 16 is provided, which, over the service life of the supply roller regardless of the current position the supply roller 16, ensures correct contact pressure in conjunction with a pressure apparatus, which pressure apparatus for example has one or more pressure springs.

[0041] A position sensor (not shown) is provided to detect the position of the axis of rotation 20. This makes it possible to determine when the supply roller has reached its wear limit, so that it can be replaced before the hot-melt adhesive 14 is completely used up.

[0042] As already mentioned, packaging materials other than paper can also be processed, it possibly being necessary to adapt the temperature of the heated roller 24, the feed speed, the contact pressure of the two rollers against one another and/or the hot-melt adhesive 14 used, it being possible for the latter to take place by simply exchanging the supply roller.

[0043] The apparatus 10 shown in FIG. 1 can be integrated into a more complex packaging machine, for example a tubular bag machine (not shown), in which the web of paper 12 coated with hot-melt adhesive 14 is further processed directly into a bag by bonding in the sealing zones.

[0044] As already discussed, the feed can be carried out by a drive of the heated roller, which is then designed as a feed roller. A more flexible adjustability of the pressure force can be achieved in the case of a heated roller 24 that runs only passively, a drive of the heated roller 24 in connection with a further drive also being possible, which drive accomplishes the actual feed movement of the web of paper or of another workpiece. In this case, the correspondingly weaker dimensioned drive of the heated roller 24 moves the roller synchronously with the feed movement, without itself exerting feed forces on the material.

[0045] In FIG. 2, a further embodiment of an apparatus 110 for applying hot-melt adhesive to a web of paper 112 is shown. In this case, a practically identical supply roller 16 is used as in the embodiment described above, which supply roller is only moved in a somewhat different manner relative to the material.

[0046] In the apparatus 112, the web of material 112 is moved over a heating surface 125 of a heating jaw 124, an application zone 126 being delimited by two support regions 128 for the supply roller 16. Ramps 130 are provided between the support regions 128 and the application zone 126, which allow a gentle transition movement of the supply roller 16 from the support regions 128 into the application zone 126.

[0047] The process of coating the web of paper with hot-melt adhesive 14 is as follows. The supply roller 16 is first lowered onto one of the unheated support regions 128. This takes place within a linear guide already mentioned in connection with the previous embodiment, which also allows the readjustment movement of the supply roller 16 as the diameter of the supply roller 16 decreases.

[0048] From a position in a support region, the supply roller 16 for applying hot-melt adhesive is moved around its axis of rotation parallel to the web of paper without driving the supply roller 16, it being possible for the supply roller, by means of the previously described linear guide, to gently rest against the web of paper 112 after leaving the ramp 130, the supply roller leaving the application zone 126 again at the opposite ramp 130 in order to pass into the opposite support region 128. Accordingly, the path of movement of the supply roller parallel to the web of paper 112 is longer than the application zone 126. It has been shown that by rolling the supply roller 16 in the application zone 126 without the roller being self-driven in the direction of rotation or the web of paper 112 being driven, a particularly uniform hot-melt adhesive application is made possible, and the supply roller is also consumed more evenly, i.e. fewer flat spots due to local melting processes are formed on the circumference of the supply roller 16.

[0049] For the heated surfaces, preferred impulse heating systems are used, which heating systems can be switched on and off again immediately. This avoids heating-up times that have to be taken into account when using conventional heating cartridges.

[0050] The invention is not restricted to one of the embodiments described above but may be modified in many ways.

[0051] All of the features and advantages arising from the claims, the description and the drawings, including structural details, spatial arrangements and method steps, may be substantial to the invention both individually and in a wide variety of combinations.

LIST OF REFERENCE SIGNS

[0052] 10 Apparatus for applying hot-melt adhesive [0053] 12 Web of paper [0054] 14 Hot-melt adhesive [0055] 16 Supply roller [0056] 18 Cardboard sleeve [0057] 20 Axis of rotation [0058] 22 Ball bearing [0059] 24 Feed roller/heated roller [0060] 25 Heated surface [0061] 110 Apparatus for applying hot-melt adhesive [0062] 112 Web of paper [0063] 124 Heating jaw [0064] 126 Application zone [0065] 128 Support regions [0066] 130 Ramps