WO2000062940A1 - Device for applying an adhesive - Google Patents

Abstract

The invention relates to a device for applying an adhesive to a workpiece, comprising a rotatable applicator roller (1), whose surface (5) has a profile and is adapted to the geometrical form of the workpiece and comprising elements (8) for the metered application of adhesive onto the applicator roller (1). Said elements (8) are arranged at a distance from the surface (5) of the applicator roller (1), in such a way that a gap is formed between the elements (8) and said surface (5). A particularly fine and even adhesive film is applied to the workpiece, if the profiled surface (5) of the applicator roller (1) has at least one cavity (9) which is specifically designed for removing undesirable particles.

Description

 Device for applying an adhesive

The invention relates in particular to the gluing of a band-shaped covering to a curved or preferably straight narrow surface (edge) of a plate element, in particular a chipboard, fiber or solid wood plate, the covering being pressed onto the narrow surface with at least one pressure element. For gluing, the adhesive is first applied to the narrow surface, which is called "edge" in technical terminology, and the covering is then pressed against the narrow surface. The plate elements used are usually coated on their top and / or bottom, but such a coating is not necessary for using the device according to the invention.

State of the art

Such gluing or coating of straight and profiled (i.e. curved) narrow surfaces of plate elements, in particular of wood-based materials, with coating materials is usually carried out using so-called edge banding machines, along which the plate elements pass at high speed. The coating materials can consist of plastic (melamine, PVC, ABS, PP) or be constructed on a paper basis. In addition to melamine and polyester, veneers can also be processed as edging material. The coating material is firmly pressed onto the narrow surfaces by means of suitable pressure devices, to which a thin film of hot melt adhesive has previously been applied. Then protruding edges are cut or milled with a drawing knife.

The straight surfaces are usually coated with the help of pressure rollers, the diameter of which can be up to 200 mm, with the aid of hot melt adhesive and edging tape. The roller pressure is used to fix the covering on the passing workpiece. The present invention is concerned with the application of thin adhesive films to workpieces, in particular to the narrow surfaces of plate elements, to which the band-shaped covering is then glued by pressing. It is known that when tape-like coverings are glued onto narrow surfaces with a narrow cross section, the adhesive, in particular the hot melt adhesive, is first applied to the narrow surface. However, the invention is not limited to the application of the adhesive films to straight edges, it can be used to apply adhesive to any work piece and also to curved or profiled edges and can be used in particular in the coating of profiles and straight surfaces.

In order to apply the adhesive films to straight narrow surfaces, an application roller is used according to the prior art, the surface of which has a grid-like structure, which is called "cording". The finer this cord, the more evenly the adhesive is applied to the narrow surface. With a fine cord, the mesh size of the lattice-like structure is about 0.1 to 1.1 mm, with a coarse cord at 1.6 mm.

The adhesive is applied from an adhesive container to the surface of the application roller using suitable means. A uniform thickness of the adhesive layer on the application roller is achieved by rod-shaped elements, so-called metering rods, which are arranged close to the application roller and form a narrow gap with the surface of the application roller and is uniform over its entire length.

The above-mentioned advantage of fine cording of the surface of the application roller is offset by the disadvantage that small particles detached from the narrow surface of the plate element, e.g. B. fine chips in chipboard, adhere to the adhesive layer of the application roller and settle in the narrow gap between the surface of the application roller and the metering rod. As a result, the adhesive film behind the metering rod is interrupted like a strip, and instead of an adhesive film closed over the width of the narrow surface, individual thin, longitudinally extending adhesive strips are applied to the narrow surface. Since the adhesive films applied to the narrow surface are relatively thin, the interruptions in the adhesive film are retained even after the band-shaped covering has been pressed on. If, on the other hand, application rollers with a coarser cord are used so that a thicker adhesive film is applied to the narrow surface of the plate element, the particles pass through the gap between the metering rod and the application roller, but the thicker adhesive film is uneven due to the coarser cord and also leads to the larger one Amount of adhesive for a lateral exit at the edges of the band-shaped covering and thus for soiling on the plate element and for an undesirable thick, clearly visible adhesive joint.

The disruptive particles at the gap between the applicator roller and the metering rod can be removed by enlarging the gap so that the particles run through the gap and are applied to the narrow surface together with the adhesive. In this case, however, since too much hot-melt adhesive is applied to the narrow surface, it emerges at the edges of the tape-like covering, as described above, and contaminates the wide surface of the usually coated plate element.

Task and solution according to the invention

The invention relates to a device for applying an adhesive, in particular hot melt adhesive, to a workpiece, in particular to a narrow surface (edge) of a plate element, preferably a chipboard, fiber or solid wood panel, with a rotatable application roller, the surface of which is profiled and the geometric shape of the Workpiece is adapted, with means for metered application of adhesive to the application roller, these means being arranged at a distance from the surface of the application roller, so that a gap is formed between the means and said surface. The invention also includes a nip width of zero if the surface of the application roller has a sufficiently deep profile, e.g. B. cord or the like, so that a sufficient amount of adhesive is transferred over the Profiiierung. The profiling can be grid-like, but other profile patterns of the surface of the application roller are also possible and are within the scope of the invention.

The invention has for its object to apply a uniform, fine adhesive film to the workpiece with the device mentioned, without Particles whose diameter is larger than the stated gap lead to malfunctions and without the workpiece being contaminated by an excess of adhesive. In particular, small particles should not get caught on the metering stick.

This object is achieved according to the invention in the device mentioned in that the profiled surface of the application roller has at least one special depression for removing unwanted particles.

The special recess enables the disruptive particles to run through the metering gap so that the particles are also applied to the workpiece, but the uniformity and coherence of the adhesive film is not impaired. Surprisingly, it was found in tests that, despite such a deepening, there was no disruptive unevenness in the application of the adhesive.

The special depression or special depressions mentioned can have a different shape. It is only important that the recess enables the particles in them to run through the narrow metering gap.

In particular, it is advantageous if the special depression is designed as a groove, which in particular extends over a width of the application roller that corresponds at least to the width of the narrow surface. In this way, an adhesive film which is closed over the entire width of the narrow surface is achieved. It is particularly preferred if the groove extends over the entire width of the application roller.

For quick removal of the particles from the application roller, it is also advantageous if the groove runs at an angle to the intended feed direction of the workpiece. The particles picked up by the narrow surface are then generally applied to the narrow surface again after only one revolution of the application roller.

Since the application roller generally has a turning axis perpendicular to the direction of advance of the plate element, it is also proposed that the groove runs obliquely to the axis of rotation of the application roller. This embodiment of the invention has proven to be particularly advantageous, since here the particles are removed from the application roller particularly quickly and there is no unevenness in the application of adhesive.

Such an oblique arrangement of the groove also creates turbulence in the liquid adhesive, for example in the melt of hot melt adhesive, so that particularly large particles, which cannot pass through the gap despite the groove, on the surface of the application roller to one of the wander on both side edges and therefore only have a brief influence, usually only during one revolution of the application roller, on the uniformity of the adhesive film.

It is also proposed that the surface have a grid-like cord. Alternatively, it is also advantageous if the surface has a profile consisting of parallel lines, the lines running axially or in the circumferential direction. The surface of the application roller can also be cords / profiles differently in different areas. It is advantageous if the mesh size of the cord or the line spacing of the profiling is 0.1 to 1.5 mm. In particular, this value should be around 1 mm. This cord is called "fine cord".

The device according to the invention can also be used in the case of profiled narrow surfaces of plate elements which are curved in cross section. For this purpose, the surface of the application roller has a corresponding, corresponding geometric shape. In particular, however, the device according to the invention is advantageous for applying adhesive to straight workpiece surfaces. For this purpose, it is proposed that the application roller essentially have the shape of a circular cylinder. For coating narrow surfaces of plate elements, it is advantageous if the application roller has a diameter of 30 to 80 mm.

It has turned out to be particularly advantageous in practice if the special depression on the surface of the application roller has a depth of 0.1 to 2.0 mm, in particular of approximately 0.1 to 1.0 mm. The groove mentioned should preferably have a width of 0.5 to 5 mm, in particular 0.5 to 4 mm and preferably 1 to 3 mm.

To remove particularly large particles with a diameter that is larger than the metering gap, it has proven to be particularly advantageous if the groove is arranged at an angle of 20 to 70 °, in particular 40 to 50 °, to the axis of rotation of the application roller.

Tape-like coverings, plate elements and adhesives to be processed with the device according to the invention

The band-shaped covering used preferably has a thickness of 0.15 to 0.2 mm.

The device according to the invention can also be used particularly well if the plate element has a thickness of 15 to 32 mm.

With the device according to the invention, all the usual plate elements can be processed. Chipboard, but also other boards such as blockboard, plywood, so-called MDF (medium-density fiberboard) and solid wood, may be mentioned as possible board elements.

The selection of the coverings to be used (edging materials) is also not critical. Edge materials made of melamine, polyester, PVC, ABS, polypropylene and veneers are suitable. Even the relatively thin edging materials made of decorative papers, which are increasingly used today and are based on paper and soaked with colored plastics, can be processed without any problems.

The choice of the adhesive to be used when using the device according to the invention is also not critical. Hot melt adhesives are preferably used, but other adhesives such as white glue can also be used.

For example, hot melt adhesives made from polymers and copolymers of synthetic resins, Rubbers, polyethylene, polypropylene, polyurethane, acrylic, vinyl acetate, ethylene vinyl acetate and polyvinyl alcohol.

Specific examples include hot melt adhesives made from the following components:

1) Elastic polymers such as block copolymers, e.g. B. styrene-butadiene, styrene-butadiene-styrene, styrene-isoprene-styrene, styrene-ethylene-butylene-styrene, styrene-ethylene-propylene-styrene;

2) ethylene vinyl acetate polymers, other ethylene esters and copolymers, e.g. B. ethylene methacrylate, ethylene n-butyl acrylate and ethylene acrylic acid;

3) polyolefins such as polyethylene and polypropylene;

4) polyvinyl acetate and copolymers with it;

5) polyacrylates;

6) polyamides;

7) polyester;

8) polyvinyl alcohols and copolymers therewith;

9) polyurethanes;

10) polystyrene;

11) polyepoxides;

12) copolymers of vinyl monomers and polyalkylene oxide polymers;

13) Aldehydes containing resins such as phenol aldehyde, urea aldehyde, melamine aldehyde and the like.

Components for strengthening the adhesion, diluents, stabilizers, antioxidants, dyes and fillers may also be present.

Examples of components for improving the adhesion are:

1) natural and modified resins,

2) polyterpene resins,

3) phenolic modified hydrocarbon resins,

4) aliphatic and aromatic hydrocarbon resins,

5) phthalate esters and

6) Hydrogenated hydrocarbons, hydrogenated resins and hydrogenated resin esters.

Examples of diluents are liquid polybutene or polypropylene, petroleum waxes such as paraffin and microcrystalline waxes, semi-liquid poly called ethylene, hydrogenated animal, fish and vegetable fats, mineral oil and synthetic waxes as well as hydrocarbon oils.

Examples of the other additives can be found in the literature.

embodiments

In the following exemplary embodiments of the invention are described in more detail with reference to drawings. Show it

FIG. 1 shows a side view in the direction of the advance of the plate element,

FIG. 2 shows a top view of the arrangement according to FIG. 1 in the direction of the axis of rotation of the application roller,

FIG. 3 shows an enlarged partial view from FIG. 2,

Figure 4 shows the winding of the surface 5 of the applicator roller according to the invention according to Figure 1 and

Figure 5 is a representation corresponding to Figure 4, but for another embodiment of the applicator roller according to the invention.

In all drawings, the same reference symbols have the same meaning and are therefore only explained once, if appropriate.

The figures show the first step in the process of gluing a band-shaped covering 4 to the narrow surface 3 of a plate element 2, e.g. B. a chipboard. Hot, still liquid hot melt adhesive is applied to the narrow surface 3 of the plate element 2 with an application roller 1. For this purpose, the hot-melt adhesive is applied from an adhesive container (not shown) to the surface 5 of the application roller 1, which has a grid-like cord with a mesh width of 1.1 mm, as is shown schematically in FIG. 1. A certain thickness of the adhesive layer to be applied is set with a metering rod 8 arranged parallel to the axis of rotation 7 of the application roller 1 and at a predetermined distance from its surface 5. This layer will then transferred from the application roller 1 to the narrow surface 3 of the plate element 2, the speed of the application roller being adapted to the throughput speed of the workpiece, so that no slippage occurs. The peripheral speed of the application roller 1 is therefore usually 20 to 100 m / min.

According to the invention, an oblique groove 9 with a width of 3 mm and a depth of 1.0 mm is now provided on the surface 5 of the application roller 1 (FIG. 1). Through this diagonally running groove, the gap between the surface 5 and the metering rod 8 is permanently opened and closed, so that disruptive particles can pass through the gap without having to influence the device from the outside. This creates an automatic, ongoing self-cleaning effect that allows very thin, even and closed hot melt adhesive applications to be set. The diagonal arrangement of the groove also ensures a certain turbulence in the melt of hot melt adhesive, which allows large particles that cannot pass through the gap between the surface 5 and the metering rod 8 despite the groove to migrate up or down on the application roller , so that only a short-term influence, usually only during a single revolution, is exerted on the uniformity of the adhesive film.

The second metering rod 10 (FIG. 3), which is also called a doctor blade, serves to return the adhesive remaining on the application roller after the application of the adhesive to the application container. This applies in particular to the adhesive in the lower and upper area of the application roller, in which the application roller is not in contact with the workpiece, since its width is generally less than the length of the application roller. When the system is switched off, the second gap is closed, thus preventing the adhesive from running out when it cools down. During operation, the second gap is always wider than the first gap between the first metering rod 8 and the application roller, so that no adhesive can accumulate on the second metering rod.

After the adhesive film has been applied, the band-shaped covering 4, which is brought to the adhesive layer by means of guide rollers 11, is pressed against the narrow surface 3 with a pressure roller 12 (FIG. 2). The development of the surface 5 of the application roller 1 according to FIG. 1 is shown in FIG. This embodiment is preferred. It can be seen that the groove 9 forms an angle α with the upper and lower edges of the surface 5, that is to say it intersects these edges at an angle.

The groove 9 can also run differently, e.g. B. as shown in Figure 5. Here, the groove 9 conforms tangentially to both edges of the surface 5, so that the groove 9 does not intersect the edge regions with a finite angle α, as is provided in the example according to FIG. 4. Other different embodiments, also with regard to other features, are also possible and are within the scope of the invention.

Reference list

Applicator roller

Panel element, chipboard

Narrow surface of a band-shaped covering

Surface of 1

Hot melt adhesive

Axis of rotation

Metering stick

Groove, special recess second metering stick

Leadership role

Pinch roller

Claims

claims 1. Device for applying an adhesive, in particular hot melt adhesive (6), to a workpiece, in particular to a narrow surface (edge) (3) of a plate element, preferably a chipboard, fiber or solid wood plate, - With a rotatable application roller (1), the surface (5) is profiled and adapted to the geometric shape of the workpiece, - With means (8) for the metered application of adhesive to the application roller (1), these means (8) being arranged at a distance from the surface (5) of the application roller (1), so that a gap between the means (8) and said surface (5) is formed, characterized in that the profiled surface (5) of the application roller (1) has at least one particularly pronounced recess (9) for removing undesired particles. 2. Device according to claim 1, characterized in that the particularly pronounced depression is designed as a groove (9), which in particular extends over a width of the application roller (1) which corresponds at least to the width of the narrow surface (3). 3. Device according to the preceding claim, characterized in that the groove (9) extends at an angle to the intended feed direction of the workpiece (2). 4. Device according to the preceding claim, characterized in that the groove (9) obliquely to the axis of rotation (7) of the applicator roller (1). 5. Device according to one of the preceding claims, characterized in that the surface (5) has a grid-like profile (cord). 6. Device according to one of claims 1 to 5, characterized in that the surface (5) of the applicator roller has a profile consisting of parallel lines, the lines running axially or in the circumferential direction. 7. The device according to claim 5 or 6, characterized in that the mesh size of the profiling (cord) or the line spacing of the profiling is 0.1 to 1.5 mm. 8. Device according to one of the preceding claims, characterized in that the application roller (1) practically has the shape of a circular cylinder and in particular has a diameter of 30 to 80 mm. 9. Device according to one of the preceding claims, characterized in that the particularly pronounced recess (9) has a depth of 0.1 to 2.0 mm, in particular of about 0.1 mm to 1.0 mm. 10. Device according to one of claims 2 to 9, characterized in that the groove (9) has a width of 0.5 to 5 mm, in particular from 0.5 to 4 mm and preferably from 1 to 3 mm. 11. Device according to one of claims 4 to 10, characterized in that the groove (9) is arranged at an angle of 20 to 70 °, in particular from 40 to 50 °, to the axis of rotation (7) of the application roller (1).