EP0050794B2 - Transfer lacquer film and method of making it - Google Patents

Abstract

A transferable enamel sheet and the process for producing it is disclosed, which consists of a carrier film, a release layer applied thereon, a paint or enamel layer and an adhesive layer whereby a neutralization layer of wax-type consistency, preferably carnuaba wax is applied to the release layer which is of the dimethyl-siloxane type (silicone). It is possible to preform two types of transferable enamel sheets. One of them is characterized by the adhesive layer between the neutralization layer and the paint or enamel layer. In this case the enamel paint itself is used as a removal coating, which can immediately be adhered to the surface to be touched up or painted. The other type is characterized by a buffer layer, preferably acrylic resin coated on the neutralization layer and by sharp defined enamel-characters being printed on the buffer layer with an adhesive layer on the outer side to transfer the characters to any surface.

Description

The invention relates to a method for producing a transferable lacquer film according to the preamble of patent claim 1.

Paint films for touching up paint on motor vehicles and processes for their production are known (GB-PS 12 32 971). In these known films, a carrier film is provided on which a solution layer consisting of 23 parts of nitrocellulose, 80 parts of solvents, 2 parts of plasticizer and 10 parts of alkyd resin is applied. After this solution layer has dried, a nitrocellulose lacquer is applied to this layer, which in turn is provided with a customary pressure-sensitive adhesive after drying. The lacquer film produced in this way can be cut out accordingly and brought with the adhesive side down over a damaged lacquer spot on the motor vehicle and stuck on under pressure. The carrier film is then peeled off. With this lacquer film, the underside of the lacquer layer is thus outside after the carrier has been pulled off, while the front is arranged below it. Films of this type have not found their way into practice. In the manner proposed there, for example, original vehicle paints cannot be used.

So-called tracing materials (NL-PS 123 093) are also known, which consist of a transparent or transparent carrier film, on which characters are printed so that they can be traced using the screen printing process. Such signs are only suitable for indoor applications, such as for labeling drawings or advertising material.

Other similar transfer materials are also known, which are transferred under pressure, for example with the tip of a pencil or a ballpoint pen (DE-AS 15 46 568 or DE-AS 12 19 831). However, in the first case there is no layer structure in the manner of the transferable lacquer film mentioned at the beginning. In the other case, it is only a matter of coordinating the printing ink and the adhesive in such a way that an exact alignment with the base to be provided with the characters is possible when the printing characters are transferred.

Finally, transfer materials are also known (US Pat. No. 3,516,904) with which printing inks can be transferred in a label-like manner, for example to plastic containers. For this purpose, four layers are applied to a carrier, for example on a suitable paper, in this transfer material, of which the release layer adjacent to the carrier is a wax layer melting under the action of heat (at 80 ° to 125 ° C.). A primer layer, a printing layer and an adhesive layer are then applied to this wax layer. Under pressure and heat, the printing layer with its primer layer can be detached from the support and can adhere to the surface to be printed. The primer layer then on the outside serves as a protective layer.

Such materials, which can only be transferred under the action of heat, are - unlike the paint films mentioned at the outset - not suitable for paint repair, for example on motor vehicles, because the devices required for heat generation, such as, for example, according to US Pat. No. 2,667,003 or US Pat. No. 3,434,902 , are either not available to the user or, such as an iron, are not suitable for non-flat surfaces.

The present invention is therefore based on the object of designing a method for producing a paint film of the type mentioned at the outset in such a way that there are no restrictions with regard to the paints to be used, so that, for example, original motor vehicle paints of any type are also present as dry material, so that Original paint repairs, but also inscriptions with original paint can be made.

To achieve this object, the characterizing features of claim 1 are provided in the method of the type mentioned. It has been shown that this is the only way to achieve complete freedom with regard to the paint to be applied. The wax layer applied as a neutralization layer ensures that a well adhering, continuous and uniformly smooth lacquer layer can be applied to the silicone layer, which is known per se as a solution layer. According to the invention, the wax layer therefore does not serve, as in the prior art, to soften by later heating and to take over the function of a solution layer, but only to neutralize the apolar properties of the silicone layer, which initially repels each layer applied to it and the formation of a layer would prevent a continuous layer of paint. By interposing the neutralization layer, the disadvantage of the dimethylsiloxane layer, which is not suitable due to the interfacial layer stress that occurs to directly take up a material layer in low-viscosity form, can be avoided in a simple manner. By interposing the wax layer, which is applied in a highly viscous state, a closed layer can be achieved. A less viscous substance would result in a less well-closed layer due to the boundary layer stresses of the solution layer underneath, so that the layers to be applied thereon would not adhere properly and evenly. The wax layer has a low cohesion and is therefore very thin. The adhesion with the siloxane layer is sufficient, but low. The new process is suitable for applying automotive paint based on acrylic resin, what was previously not possible.

By interposing the wax-like neutralization layer, which allows the application of any layers, it is also particularly advantageous and without any difficulty possible to apply and dry the adhesive layer evenly with the addition of solvents with apolar properties to this neutralization layer before the lacquer layer is applied. This adhesive layer, which is self-adhesive and cures at normal temperatures, has a high level of adhesion to the usual surfaces such as metal and wood and, after curing, a high degree of cohesion, lies between the lacquer layer and the wax layer in this process, which, however, since the composition of the adhesive layer and the wax layer is coordinated, then dissolves. If, for example, automotive paint based on acrylic resin is provided, an adhesive acrylic resin can be used as an adhesive layer, since it is related to the paint to be applied. The adhesive layer is either sprayed onto the wax layer in the low-viscosity state or also knife-coated in the higher-viscosity state. The result is a transferable lacquer film that can be used particularly well for painting or touch-up work on motor vehicles or else on other parts. A lacquer film constructed in this way has the advantage that the original lacquer is in solid film form and can be stored without damage even after production, even at high temperatures, for example in the car in summer. The adhesive layer does not dry out. The silicone layer takes on the task of preserving this adhesive and also ensures that the lacquer and adhesive layers are pulled off the carrier film properly. This type of film therefore has the advantage that a separate protective film need not be provided. Rather, the varnish itself takes on the task of a peelable layer which, after separation from the carrier film, can be glued directly onto the surface to be treated. This has the advantage that the original lacquer layer, which is otherwise only formed on the spot, can now be applied by hand and in a dry process. A method which of course has considerable advantages, both in terms of the duration of the repair or painting treatment, and advantages of a different kind. It is obvious that the thinning mist which is otherwise customary in the spraying process is completely eliminated with such handling, so that the new method is very environmentally friendly . It is also advantageous that neither brushstrokes nor drops appear on the end product, that the new dry-applied original paint can of course be polished as well as a sprayed-on paint, but that it nevertheless has the advantage that it can be stored anywhere with minimal space requirements and is accordingly easy to ship is.

A lacquer film produced in this way also has the advantage that, for example, multi-layer lacquers can be applied in exactly the same layer as is desired on the finished product. The optical effect of such multi-layer lacquers, such as metallic effect lacquers, is therefore the same as that of an original lacquer. Such paints could not previously be presented as dry paints.

Since the lacquer layer is then on the outside in this type of production, when using suitable carrier films, such as clear polyester film based on polyethylene terephthalate, an original stoving lacquer, which consists of two components that react at 120 °, can also be applied to the film. The film is stable at temperatures between 100 ° and 200 °. Such lacquer can therefore also be applied in the lacquer baking process. This results in optimal cross-linking between the two paint components after about 20 minutes. Large molecules have formed, which give the special advantages of the stove enamel. Such a paint has so far only been able to be applied directly to motor vehicles or the like using customary paint touch-up methods.

Applying varnish in the form of sharply delimited symbols, which are to be applied, for example, using the screen printing process and provided with adhesive on the side facing away from the wax layer, is somewhat more difficult in order to be transferred to surfaces to be labeled. It has been shown that sharply delimited letters, numbers or the like can only be printed on without difficulty if a buffer layer is applied to the wax-like neutralization layer, which can consist of an acrylic resin which is compatible with the maximum possible amount of solvents with apolar Properties. This resin can be spread and dried in a uniform layer on the wax layer. Like the adhesive layer, it dissolves the wax layer. After printing, the aggressive solvents of the varnish used for screen printing dissolve this resin layer up to the edges of the printed areas. The drying time of the paint and the dissolution rate of the aggressive solvents must be coordinated so that the paint is dry before it reaches the silicone layer.

The lacquer film produced in this way, in which the adhesive layer is initially on the outside, is particularly recommended for lettering or the like, where it is important to give them a certain hold before the lacquer characters stick. It has been shown that the transfer of letters or numbers from lacquer with a film produced by this method is much easier than was the case with previous tracing materials. There is also the possibility to use varnishes. The transfer of the symbols from, the new paint film to the primer does not need with the help of separate spatulas or with Ballpoint pens, which put considerable pressure on the letters. The paint symbols can be transferred from the new film in a simple manner by pressing on them with a handkerchief or only by hand, as is the case with the other type of paint films with the adhesive lying between the paint layer and the carrier. As is known per se, the symbols are applied by screen printing. When transferring, there is no stretching and no deformation of the paint symbols because there is practically no adhesion to the carrier film, but there is good adhesive strength of the adhesive, so that easy and direct transfer can be achieved at low pressure.

In the following description, exemplary embodiments for the composition of the individual characteristic layers are given, and an exemplary embodiment of an apparatus for carrying out the new production method is described with reference to a drawing. The drawing shows a schematic longitudinal section through a continuously operating device with which both the adhesive layer and the lacquer layer are sprayed on. As already indicated, other application methods are also possible.

In the drawing, a carrying and conveyor track (1) is shown, which consists of an elongated support frame (2) for a rotating conveyor belt, not shown, which is moved in the direction of the arrows (3). Above the carrying and conveying path (1), which in the exemplary embodiment is about twenty times as long as it is wide, several devices are provided for treating the surface of a polyester film which is wound up into a roll 4 and from this roll 4 via a deflection roll 5 the carrier and conveyor track 1 is placed. This carrier film 6 consists, for. B. from an optically clear polyester film based on polyethylene terephthalate. This material has all the conditions for producing the paint film according to the invention. It has a very smooth surface, is well resistant to the essentially aromatic solvents which are used in the other components of the transfer material or during its application, it is stable at temperatures which are used in the paint drying or paint baking process, i.e. H. between 100 ° C and 200 ° C. Of course, it would also be possible to provide a polypropylene film that is not resistant to the high temperatures mentioned above. However, longer drying times would then have to be accepted, and it would not be possible, as previously indicated, to apply original stove enamel to the film.

This carrier film 6 has been provided with a dimethylsiloxane (silicone) layer on one side in a previous operation. This layer serves as a solution layer and ensures that the layers applied later can also be detached from the carrier film. Due to its apolar property, this silicone layer repels almost every layer applied to it. The silicone layer lies inside the wound roll 4. As a result of the deflection by means of the roller 5, the silicone layer reaches the top during the movement on the carrying and conveyor track 1. The carrier web 6 therefore lies with its uncoated side on the carrier and conveyor web 1.

The silicone layer applied to the carrier film 6 is not suitable because of the boundary layer tensions which occur in order to apply a low-viscosity material layer directly thereon. The applied material would contract into drops. This also applies to paints. In a first treatment station 7, a static discharge of the carrier film 6 is therefore first carried out, and a wax-like layer, for. B. Karnauba wax applied to the silicone layer of the film 6, this wax-like layer is thinned with turpentine to an extremely viscous substance. The correspondingly diluted wax is applied directly to the siloxane layer using the doctor blade 8. Since the wax is highly viscous, a closed layer can be achieved. A less viscous substance would not result in a closed layer due to the boundary layer stresses previously indicated. The wax used chemically consists of long, unbranched hydrocarbon chains with an average length of carbon atoms with a COOH (acid) group at some points on the chain. The wax layer has a low cohesion and is therefore very thin. The adhesion with the siloxane layer is sufficient, but low. When moving in the direction of arrow 3, the film 6 then passes through an evaporation zone 9, which is provided with a ventilation duct 10, which leads from the installation space to the outside in a manner not shown. In the exemplary embodiment, a spray booth 11 is arranged behind the evaporation zone, in which a certain drying of the wax takes place on the siloxane layer, in which a self-adhesive resin is applied as an adhesive layer to the wax layer with the aid of several spray nozzles 12. This resin, e.g. B. self-adhesive acrylic resin cures at normal temperatures and has a large adhesive force compared to the usual surfaces such as metal and wood and after curing a high degree of cohesion. The adhesive layer must be weatherproof and also resistant to UV rays. When using acrylic resin, acrylic resin paints can be applied. The self-adhesive resin is sprayed onto the wax layer in a low-viscosity state, with a solids content of 25 to 30 g / m ² . A mirror-smooth, high-gloss surface can be obtained by using a spraying process, which is particularly important when using high-gloss lacquers to be applied later.

After spraying, the adhesive floats on the wax layer, whereby a low level of adhesion to this wax layer arises.

• - 100 Teile Etastomer-(acrytsäureester) zur Herbeiführung einer guten Kohäsion,
• - 5 Teile Celloleim 11 (technischer Hydroabietylalkohol) zur Herbeiführung der Klebwirkung,
• - 0,2 Teile Desmodur L - das ist eine Lösung von 0,2 % Isocyanat in 75 % Äthylacetat.

A good adhesive composition is as follows:

• - 100 parts of estromer (acrylic acid ester) to achieve good cohesion,
• 5 parts of cello glue 11 (technical hydroabietyl alcohol) to achieve the adhesive effect,
• - 0.2 parts Desmodur L - this is a solution of 0.2% isocyanate in 75% ethyl acetate.

The Desmodur L fraction ensures that the adhesive cross-links, which increases cohesion and consequently weather resistance. The addition of the isocyanate results in cross-connections between the molecules, i.e. network formation through polymerization.

• - 70% aromatischen Kohlenwasserstoffen (technisches Toluol)
• - 30 % Isoamylacetat.

The adhesive composition described above is diluted with a solvent consisting of

• - 70% aromatic hydrocarbons (technical toluene)
• - 30% isoamyl acetate.

• - 70 Teilen Waschbenzin auf 30 Teile Leim. Dieses Lösungsmittel zum Spritzbarmachen des Leimes verdampft sehr schnell und verleiht der Spritzlösung gute Fließeigenschaften.
• - 13 Teilen aliphatischen Kohlenwasserstoffen mit einer Kettenlänge von 12 bis 16 und einem Siedepunkt von 170 °C. Diese Zugabe soll vermeiden, daß der Leim schon während des Spritzvorgangs an der Luft trocknet, wodurch Fadenbildung auftreten kann.

Adhesive plus solvent together form a non-sprayable, viscous liquid. To make it sprayable, a second solvent is added, consisting of:

• - 70 parts of mineral spirits per 30 parts of glue. This solvent for spraying the glue evaporates very quickly and gives the spray solution good flow properties.
• - 13 parts of aliphatic hydrocarbons with a chain length of 12 to 16 and a boiling point of 170 ° C. This addition is intended to prevent the glue from drying in the air during the spraying process, as a result of which threading can occur.

Of course, it is also possible to provide another method, for example the method using a doctor blade, instead of a spraying method for applying the adhesive layer, but the viscosity must then be adjusted differently.

Following this adhesive application device 11, an evaporation zone 13 with a ventilation channel 14 is again provided. The film 6 then passes into a drying room 15, which is provided with guide rollers 16 and 17 for the carrier film web 6. The guide roller 17 is arranged at such a distance above the support and conveyor track 1, but aligned parallel to this, that there is enough path length of the film 6 of the drying room 15 to achieve a quick drying of the adhesive by supplying warm air.

In order to then bring the still hot film back to room temperature, a cooling zone 18 is provided before the film 6, lying on the carrying and conveying device 1, again runs into a paint spraying system 19, in which, in the present case, with the aid of conventional spray nozzles the type of across the carrying and conveyor track 1 supply pipes 20 with nozzles, a first coat of paint is applied, which is then subjected to an intense warm air supply below the drying nozzle 21 in the embodiment, so that another coat of paint can then be applied to the pre-dried paint layer . All spray nozzles 20 are surrounded in a manner known per se by a suction housing which removes the solvent vapors. In the spray booth 19, two-component paints or multi-layer paints can also be applied, as is readily apparent. These varnishes are then guided with the carrier film 6 through an evaporation zone 22 with a drain channel 23 and then again enter a drying chamber 24, which in turn is provided with guide and deflection rollers 18 and 17, such as the drying chamber 15, which runs parallel to the carrier and Conveyor path 1 are aligned and ensure that the carrier film 6 is guided upwards while it is exposed to the supply of warm air through the channel 25. The arrangement of the two drying rooms 15 and 24, in which certain sections of the film are pulled upward, saves space in the conveying direction 3 for the overall system. The film leaving the drying room 24 is dried. It has a continuous lacquer layer which, depending on the choice of temperatures in the drying room 24, can correspond, for example, to the original stove enamel of motor vehicles. The film is cut into pieces and packed by a schematically indicated cutting device 26. The required sizes for paint repair work can then be cut out from these individual pieces of film. The paint itself takes on the function of a continuous film which can be pulled off the carrier film 6 and can be glued to the surfaces to be treated with its adhesive layer by pressure.

Of course, it is also possible to punch out strips or letters from the film, just as it is already possible in the spray booth 19 to spray strips or letters or the like through appropriate covers. It is also possible to apply the paint color in another process, for example also to apply or pour on or to apply it by rotating brushes. However, the example shown has the advantage that it corresponds to the original application of motor vehicle paints, so that at the end of the manufacturing process an original motor vehicle paint can be present on a film, which can be applied at any time using the dry process. The advantage of the new paint film, in addition to the excellent weather resistance of the paint used, is above all that the adhesive under the paint layer does not dry out even after a long time. The silicone layer underneath takes on a preservation function.

. It should also be mentioned that a two-component acrylate paint can be applied to the adhesive layer in the spray booth, which is extremely weatherproof and chemically closely matches the previously used adhesive. During the color curing process, which occurs essentially as a result of the cyanate-acrylate reaction the color pushes itself into the adhesive to some extent, which creates a mechanical anchor between the adhesive and the paint layer. This anchoring between the adhesive and the lacquer layer is further promoted in that the lacquer is processed as second component isocyanate, which enters into a reaction with the top layer of the glue, which is not completely crosslinked even as a result of the low isocyanate content. In this way, an inseparable adhesive-lacquer connection is obtained, which then enables the lacquer layer to be easily detached from the support and contributes to the fact that the original lacquer can be used as a kind of plaster for repair work, which was previously not possible. The great advantage is, as already indicated, that in multi-component or multi-layer paints the same layering is present as in the original sprayed automotive parts, so that the spatial arrangement, for example of metallic particles, is the same as on the vehicle . The visual effect remains the same. This effect can never be achieved with known types of film.

Films of the second type, in which a buffer layer, e.g. B. in the form of an acrylic resin, and then only paint and adhesive is applied, since it is usually a film for transferring individual symbols, such as letters or numbers, stripes, or the like that after the paint symbols have been printed on, the adhesive can be applied with the aid of the register in such a way that it is only present at the locations where the paint symbols are also present.

Claims (5)

1. Method of manufacturing a lacquer film which is transferable by pressing by hand, on which on a carrier film, in particular in the form of a transparent polyester film on a polyethyleneterephthalate basis, are applied a solvent coating, a lacquer layer and a layer of adhesive, characterised in that the solvent coating is of the dimethyl siloxane type (silicone), in that a neutralising layer is applied to the side of the carrier film provided with the solvent coating, which consists of a wax from long and branched hydrocarbon chains with an average length of 30 carbon atoms and with a COOH(acid) group at a number of points on the chain, which is applied in the very viscous condition and in that the additional layers are applied after this neutralising layer has been dried, whereby the layer next to the neutralising layer has been so adapted in its combination with solvents to the composition of the lacquer layer and wax and silicone layer, that the neutralising layer is subsequently dissolved.

2. Method according to claim 1, characterised in that a layer formed from carnauba wax is applied as a neutralising layer.

3. Method according to claim 1, characterised in that a layer made of an acrylate resin-based vehicle lacquer is applied as a lacquer layer and that an acrylate adhesive is applied as the adhesive layer.

4. Method according to claim 1, characterised in that the adhesive layer with the addition of solvents with non-polar properties is applied evenly to the neutralising layer and dried before the lacquer layer is applied.

5. Method according to claim 1, characterised in that after the drying of the neutralising layer a buffer layer with the addition of solvents with non-polar properties is applied and dried, before the lacquer layer is applied.

Images