EP0794855B1 - Device and method for the treatment of surfaces - Google Patents

Abstract

A process and apparatus for edge coating a substrate is provided. A process provides a layer of a formable coating material on a transfer belt which layer of formable material has a variable thickness over the width of the layer, applying a layer of the formable coating material on the transfer belt to the edge surface to produce a coated edge surface and smoothing the coated edge surface by contact with a smoothing belt. The coating on the edge surface is sufficiently thick to cover and smooth irregularities in the edge surface of the substrate. The coated edge surface can be further treated by the usual methods for coating edge surfaces of flat substrates. The apparatus comprises the roller or nozzle to provide the layer of formable material of variable thickness on the transfer belt, the transfer belt carries the coating material to the edge surface and the transfer belt can act as a smoothing belt to provide an edge surface with the coating material with all of the irregularities obscured.

Description

The invention relates to a method or a device for treating surfaces.

Especially in the furniture industry Large-scale surface treatment process used. Usually they are used there Wood materials are not in their original form Leave appearance, but get one finishing surface coating. Mostly acts it is a melamine coating. Veneers, decorative laminates or decorative films are also used as coating material.

The coating of side surfaces, edges or generally from narrow areas is often done by a special edge material. For example it is a edge band or a so-called Narrow area belt, which by means of a Glue is applied to the narrow surfaces. This process is commonly called edge banding designated.

However, there is often a desire to narrow the Flat or edges from aesthetic Round off reasons or for functional reasons Reasons to provide profiled surfaces. At the coating of such soft "contours" in addition to the edge banding described above, the is also referred to as the softforming process, other coating processes used.

One way to do a surface coating consists of the coating material as edge material to use the top and bottom. First, the coating material on the top or bottom of a applied to the plate material to be coated. This is preferably done using a dispersion adhesive. In the area of those to be coated Edge usually has sufficient material protrusion, the appropriate way, usually through the addition of heat. Subsequently becomes the flexible material overhang bent around the edge to be coated and by means of a dispersion or hot melt adhesive glued. This process is also called the postforming process designated.

In a modification of the postforming process mentioned above the material overhang becomes Free milling achieved, under the desired Material excess material removed becomes. This process is called the direct postforming process designated.

However, all processes have in common that a solid coating material is used that accordingly difficult to handle and beyond is expensive, not least because it cannot be recycled Cutting waste.

In addition, the surfaces to be coated have often large bumps, blowholes, etc. on. This applies in particular to chipboard.

Such a surface condition leads to coating with one of the specified methods to a strikingly restless, "humped", wavy material surface that has the look, for example of the later piece of furniture. To bring about an improvement often thicker edge or coating materials used that to a sufficient extent can compensate for the unevenness of the surface and a shining through (telegraphing) of the underground avoid the surface. With the increase however, the material thickness is also an increase the restoring force of the bent coating material connected. This in turn requires an extended one Pressure path for gluing such stiffer coating material. Furthermore are such thicker coating materials in usually more expensive.

This also applies to the postforming processes described these disadvantages cannot be eliminated.

GB-A-745 057 also describes a method for the treatment of Surfaces known, being a thermoplastic Coating material is applied to the surface and that applied coating material by means of a Surface of the band passing by is then smoothed.

The object of the present invention is therefore in being a process, respectively Specify device with or with which eliminates the aforementioned drawbacks and a surface smoothing treatment is possible in a simple manner.

This problem is solved by a method that comprises the steps mentioned in claim 1, and also by a device that features of claim 14.

The fact that a moldable, non-solid coating material simplification can be used the coating in contrast to the aforementioned method, for example folding a material overhang. The desired Smoothing of the applied coating material is achieved by a smoothing band that easy to use compared to rollers or sliding shoes and is therefore inexpensive. The on this Wise coated surface is now for another one Coating prepared. Because of the high However, goodness can be left as it is.

According to the invention, the coating material is by means of a transfer belt applied to the surface. This has the advantage that for the Order of the material does not match the profile of the Coating roller adapted to the coating surface necessary is. Especially with the multitude of is the production of different edge profiles such application rollers adapted to the profiles or also specially adapted application nozzles time consuming and extremely expensive. Moreover, can not coated different profiles in a short time become. Preferably the transfer belt also used as a smoothing belt, so that on smoothing rollers or on smoothing shoes can be dispensed with. Another savings effect is the consequence.

The application of the coating material is preferred on the surface to be treated Press force accomplished. A suitable printing device acts on the tape on the uncoated Side with a force that pushes the coated transfer belt side to the coating surface causes.

An improvement in the material order is made through additional heat treatment of the coating material achieved. Infrared radiators, Hot air blower, high frequency radiator or the like used.

In a preferred development of the method or the device becomes the coating material immediately before the order on the surface to be coated onto the transfer belt upset. The order is preferably placed via an appropriate applicator roller or Application nozzle that the material to be set in a Material thickness brings on the transfer belt. When determining the material thickness, it is advantageous this in the middle area of the transfer belt to increase. As already described, are especially in this area of those to be coated Surface the most bumps so that consequently more material must be used there.

In a further advantageous embodiment of the invention the transfer belt is removed from the patient to be treated Surface peeled off, taking the material beforehand penetrated into the pores of the surface to be treated and is solidified, so that this when pulling off of the transfer ribbon does not stick to it.

In an advantageous embodiment of the invention the removed transfer belt back to the application roller returned so that the use of a Endless belt is possible.

Further advantageous embodiments are the subclaims refer to.

The present invention is illustrated by way of example several embodiments with reference to a drawing explained in more detail. The shows single figure is a schematic representation of a Transfer coating device, based on which also the method according to the invention is described.

A wooden plate to be processed, respectively a chipboard 1 with two profiled narrow surfaces 3 lies on a conveyor belt 5. The conveyor belt 5 is about appropriate, not in the figure shown drive units driven and transported the chipboard 1 in the arrow indicated direction, in the drawing from from left to right. Along the conveyor belt 5 there are several at a distance in a pressure zone 7 mutually arranged printing devices 9.

This is preferably pressure and / or sliding shoes 9. pressure rollers or a combination from pressure rollers and sliding shoes 9 can however, can also be used.

From a role also called a supply role 13, a transfer belt 11 is unwound, which the Pressure zone 7 between the conveyor belt 5 respectively the chipboard 1 and the printing device 9 passes through and another roll 15 is rewound. The drive device usually acts for the transport of the transfer belt 11 with the other role 15 together.

Since preferably the transport speed of the Transfer bands of the transport speed of the Chipboard 1 corresponds to the drive speed the further role 15 depending on the waked Diameter set.

The control mechanism for the further roller 15 can omitted if instead of the unwound from the roll 13 Conveyor belt an endless transfer belt 11, which is shown in broken lines in the figure is used. Instead of the two rollers 13 and 15 are different pulleys in this case 17 necessary after the transfer belt 11 Pass through pressure zone 7 back to the beginning to lead. The endless transfer belt 11 is used by the coating plates 1 with drawn; it can also a separate drive can be provided.

In the transport direction in front of the pressure zone 7 is on Transport path of the transfer belt 11 an application nozzle or an applicator roller 19 is arranged. Opposite her there is a pressing device 21, wherein the transfer belt 11 between these two elements is passed through. In the figure is not shown that the applicator roller 19th with a coating material is supplied. The application roller 19 has one suitable for the application of flowable material Surface that may have dents, grooves or the like has to the material application thickness across the width of the roller or Change transfer bands. With an application nozzle the nozzle slot is widened accordingly or narrowed to also a variable across the width To achieve material thickness.

Between the application roller 19 and the printing zone 7 a fixing roller 23 is provided which the transfer belt 11 in a first adhesive contact with the coating narrow surface 3 brings.

Is along the transport path of the transfer belt 11 a cleaning device 25 is provided, the Transfer belt 11 detaches adhering impurities.

Under certain circumstances, this could result in a clean material application prevent by the application roller 19.

In the drawing, 5 is at the end of the conveyor belt schematically shows a processing area 27, in which, for example, regrinding the edges or the actual softforming or Postforming process is carried out.

The following is the transfer coating process based on the arrangement described above explained in more detail:

The thing to be applied Material is fed over the application roller 19 applied to one side of the transfer belt 11. There the chipboard to be coated 1 piece by piece the conveyor belt 5 are transported, works the application roller 19 preferably at intervals. It starts with the application when the one to be coated Chipboard 1 still a transport route to pass through the fixing roller 23, the transport route the transfer belt 11 to the fixing roller 23 corresponds; thus the beginning of the strikes with material wetted transfer ribbon section with the front Edge of the chipboard on the fixing roller 23 together. The length of the wetted transfer belt section corresponds to the edge length of the Narrow area 3. Such an interval control is very easily via appropriate sensors, for example Photoelectric sensors arranged in suitable places are realizable.

The pressure device 21 ensures when applying the Materials that the transfer belt does not give in or evade the pressure of the application roller. she thus serves as an abutment.

The fixing roller 23 then brings the coated Transfer belt 11 in contact with the Narrow area 3, so that a first fixation of the Transfer belt 11 takes place on the narrow surface 3.

When the chipboard 1 enters the pressure zone 7 is preferably the transfer belt 11 first a certain, adjustable force against the Closest to the pressure or sliding block Section of the narrow surface 3 pressed. The The pressing / pressing force must be so great be that the material fits well in the Pores of the narrow surface 3 penetrates. The first Pressure or sliding shoe 9 following another Pressure or sliding shoes are like this positioned that to the end of pressure zone 7 too the other areas of the narrow surface 3 with one Contact pressure are applied. The pressure respectively Sliding shoes are preferred to the Adjusted contour of the narrow surface 3.

In the drawing are only schematically pressure or way Slide shoes 9 shown. It is however also possible, pressure rollers alone or in Combination with pressure or sliding shoes to use in the pressure zone. The exact arrangement of the individual printing elements is the average specialist known; for a detailed explanation is therefore omitted at this point.

The length of the pressure zone 7 or Transport speed of the chipboard 1 must be designed so that applied to the narrow surface 3 Material until it leaves the printing zone 7 has hardened to ensure good anchoring of the Material in the narrow surface to reach.

The transfer belt 11 is connected to the printing zone 7 removed from the chipboard 1 again.

The chipboard 1 with the coated narrow surface 3 is then transported into the processing area 27, in which the actual edge banding in Softforming or postforming processes is carried out. Because the material the originally existing bumps on the Narrow area 3 compensates and a very smooth Surface delivers is a flawless smooth final narrow surface coating with the above known methods possible.

The effect of the pressure or sliding shoes 9 in the pressure zone 7 can be caused by additional heat, for example by infrared emitters, High frequency radiator or hot air blower, increased become. Improved by the higher temperature the fluidity of the material, so that this better and deeper in the pores the narrow surface 3 can penetrate. At the same time or even before reaching the fixing roller 23 also the narrow surface 3 of the particle board to be coated 1 heated, for example, by infrared radiation be, which has the effect just mentioned can be strengthened.

The material itself has to be procured in this way be that it is at the usual usage temperatures of furniture that is usually between -10 ° to 100 ° C, not softened and maintains its strength. Preferably the Softening point chosen so high that with machine Smooth grinding or smooth polishing Frictional heat does not become an undesirable Softening the Leads. The softer material in this case the sanding belts would be relative smear quickly and therefore prematurely unusable do. Furthermore, the im for example subsequent softforming or Hot applied postforming process Hot melt adhesive does not soften to a high degree and thus possibly to an unwanted deformation of the pretreatment of the narrow surfaces lead applied material.

To order the material on the transfer belt 11 commercially available hot melt applicators should be able to use it in a temperature range of 150 ° - 250 ° C, preferably 180 ° - 230 ° C sufficient be flowable. Good flowability of the material is important in that it does that Transfer belt can wet better, better on the narrow surface 3 to be coated can be applied and moreover better in the pores of the particle board can penetrate. Too much penetration too is avoided, the one facing away from the narrow side Side of the coating or the conveyor belt cooled, for example by means of a Cold air shower or a cooling roller. It freezes the part of the coating material touching the conveyor belt very quickly, so less in the surface "sagging".

By choosing a material that is relative Freezes quickly, the necessary length of stay the chipboard 1 in the pressure zone 7 can be shortened. Otherwise, the transfer belt 11 of better peel off a completely solidified material.

The material used is easy to stick, that is, that there is a glue to the adhesive applied in later processes has high affinity. As reactive thermoplastics for example isocyanate-terminated PUR prepolymer in addition to 2-component systems based on epoxy / amine or UV-curing systems based on acrylate, Methacrylate or unsaturated polyester for the production of Thermosets can be used.

The one that serves as the carrier for the coating material Transfer belt must be flexible enough to by means of the pressure shoes 9 or pressure rollers, easy to conform to the contour of the narrow surface 3 to be. The transfer belt 11 must further be heat stable, so that it is in the high application temperatures of the Material is not permanently deformed. Furthermore it should also be due to a rapid succession of warming and cooling, as is particularly the case with the Use as an endless belt occurs, insensitive his.

For example, have proven to be particularly good materials Polypropylene, polyester, silicone, however also certain commercially available thermosetting edgebands highlighted on paper. All of these Common to all materials is that they are sufficient low affinity for thermoplastic material have so that the transfer belt easily from the pre-treated chipboard is removable.

As previously described, the one used Material on a later process applied hot melt adhesive has a great affinity have a good connection between the two Materials is achieved. An improvement on this Adhesive bond can be achieved in that the applied to the narrow surface 3

material is heated, for example by Infrared radiation or through a hot air shower. Heating causes liquefaction / Plasticizing the at least top layer of the Material, which causes the merging process its top layer with the applied on the edge material Hot melt adhesive is promoted and better Adhesion of the edge material leads. Here, however, is about make sure that the material is not too much liquefied and deformed.

In the way of the heating described above, at least top layer of applied material and its liquefaction, this material can can be used as an adhesive. requirement this is, however, that the narrow surface is complete or at least all critical points for a good adhesive bond Narrow area covered with the material are.

Otherwise, the quality of the narrow surface 3 applied material so selected be that a pretreated or coated narrow surface without further finishing can be painted or coated with a hot stamping foil.

The applied material solidifies after the Coating like a common thermoplastic, will but then chemically to a thermoset, for example under the influence of heat or moisture. Such reactive hot melt adhesives are based on polyurethane known. The solidified coating composition which has reacted in this way is Heat, water and shockproof as well as chemically resistant.

Color pigments can also be added to the coating material mix, so that a ready-to-use Edge with the desired color can be achieved is. Of course, the crosslinked coating mass can also be painted, however a paint system must be selected, the solvent the not yet hardened coating mass does not swell or even dissolve. Here offers a water-based paint system.

The coating composition should be after curing an optically pleasing structure, for example have a wood grain structure, that is still non-crosslinked coating mass with the help of Machining prague rollers. The embossing rollers must however, have an adhesive surface so they easily detach from the coating material and do not damage them.

In addition to the coating process described above it is also possible to use the coating material directly on the surface using suitable application devices, such as an applicator roller or an application nozzle to apply and only afterwards with the help of a circumferential smoothing belt to smooth out. In addition, a lot of material should be applied , both methods can also be combined, initially with one Application device applies a first amount of material and that before described transfer belt the second amount of material. The smoothing takes place again through the transfer belt.

The coating process described is particularly for wood-based materials, such as solid wood, chipboard or MDF (Medium Densitive Fiber). It can also be coated with plastic materials or metals With the help of the procedure described.

In addition to smoothing surfaces, the coating material also offers Protection against mechanical stress. For example Metal rails on the edges of concrete formwork boards through a Coating can be replaced with a material that becomes a thermoset hardens. Of course, other areas of application are also conceivable.

For example, it can be used on the smoothed narrow surface of a wood-based panel a chipboard, a strip of a colored, decorative resin-impregnated Paper are laminated, under pressure and heat in such a way that the resin flows away and hardens to an irreversible thermoset. The Impregnation resin can e.g. pure melamine resin or melamine / urea resin blends consist. Such impregnated papers will be in the chipboard industry for direct coating of wood-based panels in various presses - multi-day, short-cycle, continuous presses - used. If the same resin-impregnated paper is used both for Coating the top and bottom (wide areas) as well as Laminating the smoothed narrow surface of the wood-based panel used then you get workpieces that all around on all surfaces have the same thermosetting surface material.

Claims (27)

1. A process for treating surfaces (3), more particularly narrow surfaces (3), a thermoformable coating material being applied to the surface (3) and the coating material applied then being smoothed and/or embossed and/or textured by means of a belt (11) travelling past the surface (3), characterized in that a reactive polyurethane-based hotmelt adhesive, which first sets physically after coating and is then chemically crosslinked to form a thermoset, is used instead of a thermoplastic material.
2. A process as claimed in claim 1, characterized in that the coating material is applied to the surface (3) by means of a transfer belt (11).
3. A process as claimed in claim 1 or 2, characterized in that the coating material is applied by an application roller and/or an application nozzle (19).
4. A process as claimed in claim 2, characterized in that the transfer belt (11) is additionally used as a smoothing belt.
5. A process as claimed in claim 2 or 4, characterized in that the transfer belt (11) is coated on one side with the coating material and, during treatment of the surface (3), a pressure is applied to that side of the transfer belt (11) which has not been coated with the coating material.
6. A process as claimed in any of the preceding claims, characterized in that the coating material is heated during its application to the transfer belt (11) and/or the surface (3).
7. A process as claimed in any of the preceding claims, characterized in that the coating material is applied to the transfer belt (11) immediately before the pretreatment of the surface (3), preferably by means of an application nozzle or roller (19).
8. A process as claimed in any of the preceding claims, characterized in that the transfer belt (11) is cooled on that side remote from the surface (3).
9. A process as claimed in any of the preceding claims, characterized in that the transfer belt (11) is removed from the surface (3) after the treatment.
10. A process as claimed in any of the preceding claims, characterized in that an endless belt is used as the transfer belt (11).
11. A process as claimed in any of the preceding claims, characterized in that a heat-resistant, high flexibility belt is used as the transfer belt (11).
12. A process as claimed in any of the preceding claims, characterized in that at least one side of the transfer belt (11) is thoroughly wettable with the thermoplastic material.
13. A process as claimed in any of the preceding claims, characterized in that polypropylene, silicone and/or thermoset edge bands are used as the transfer belt.
14. A hotmelt applicator for pretreating surfaces for carrying out the process claimed in any of claims 1 to 13, characterized by a transfer system which applies a coating material to the surface (3) and a smoothing system which smooths the coating material applied.
15. An applicator as claimed in claim 14, characterized in that the transfer system comprises a transfer belt (11) which takes up the coating material and transfers it to the surface (3).
16. An applicator as claimed in claim 14, characterized in that the transfer system comprises application rollers and/or application nozzles (19) for applying the coating material.
17. An applicator as claimed in any of claims 14 to 16, characterized in that the smoothing system comprises a smoothing belt and/or a slide block (9).
18. An applicator as claimed in any of claims 14 to 17, characterized in that the smoothing belt is the transfer belt (11).
19. An applicator as claimed in claim 18, characterized in that the pressure system (9) comprises pressure rolls, pressure pads and/or slide blocks (9).
20. An applicator as claimed in any of claims 17 to 19, characterized in that the transport system comprises a heat source which heats the transfer belt (11) and the coating material before and/or during the application of pressure.
21. An applicator as claimed in any of claims 17 to 20, characterized by an application system (19) which precedes the pressure system (9) in the transport direction and which applies the thermoplastic material to the transfer belt (11).
22. An applicator as claimed in claim 21, characterized in that the application system comprises at least one application roller (19) and/or an application nozzle which applies the thermoplastic material to the transfer belt (11) guided past the application roller (19) and/or nozzle.
23. An applicator as claimed in claim 21 or 22, characterized in that the application system (19) is designed in such a way that the thermoplastic material is applied in a variable thickness over the width of the transfer belt (11).
24. An applicator as claimed in claim 23, characterized in that the application roller (19) has depressions in its surface to achieve a greater coating thickness on the transfer belt (11) and/or in that the application nozzle is widened at the corresponding places of the nozzle slit.
25. An applicator as claimed in any of claims 19 to 24, characterized by a removal system which removes the transfer belt (11) from the surface after the pretreatment.
26. An applicator as claimed in any of claims 14 to 25, characterized by a transport system which transports the transfer belt (11) through the pressure zone (7) in which the surface (3) is pretreated.
27. An applicator as claimed in claim 26, characterized in that the transport system is designed in such a way that an endless transfer belt (11) can be used.

Images