DE102008028398A1 - Method for production of substrates coated with colors, lacquers or layers, involves exposing stationary electrical field to substrate before coating or coated substrate before hardness - Google Patents

Abstract

The invention relates to a method and an apparatus for producing paints, lacquers or increased adhesion or adhesion, comprising applying at least one first layer to the substrate, drying or curing the layer and optionally applying, drying and / or curing further layers, wherein the substrate and / or the coating comprises charge carriers in the form of electron gases or dipoles, wherein the substrate before the first coating or the coated substrate prior to the first curing is exposed to a stationary electric field and on the surface of the substrate or in the boundary layer between substrate and coating forces act on the charge carriers.

Description

• – das Auftragen mindestens einer ersten Schicht auf das Substrat
• – das Trocknen oder Härten der Schicht
• – und gegebenenfalls das Auftragen, Trocknen und/oder Härten weiterer Schichten
• – wobei das Substrat und/oder die Beschichtung Ladungsträger in Form von Elektronengasen oder von Dipolen aufweist.

The invention relates to a process and a device for the production of substrates coated with paints, varnishes or similar coatings having increased adhesion or improved adhesion

• - applying at least a first layer to the substrate
• - drying or curing of the layer
• - And optionally the application, drying and / or curing of further layers
• - Wherein the substrate and / or the coating comprises charge carriers in the form of electron gases or of dipoles.

From the DE 69704860 T2 For example, it is known to transfer powdered powder particles charged to coat a cardboard or paper-like substrate to the substrate by means of an electric field and then to melt the powder particles into a powder coating and then cure. Curing can also be achieved by radiation curing either by ultraviolet (UV) or electron beam curing. Preferably, a photoinitiator with the binder composition is added to the powder coating. As a result, the melting can be carried out at relatively low temperatures of 50 to 150 ° C (page 10, line 30).

Of the Transfer of the powder particles in the electric field occurs after the technology known in photocopiers or laser printers. Depending on the conductivity of the substrate can a pretreatment, such as a corona discharge made or a moving or fixed counter electrode be installed (page 3, lines 26 and 27).

tries have shown that pure UV curing is not an absolute secure adhesion of the coating on the substrate allows. In addition, ozone is generated and the discharge occurs environmental pollution, requiring ex-protection is. In a corona treatment are high-frequency high-voltage alternating fields used, which cause an EMC burden on the environment. About that In addition, the process is very complicated, as for the high-voltage alternating fields High-performance transformers are needed.

In a similar method according to DE 60303011 T2 The production of solid coatings on an inorganic or organic substrate by a low-temperature plasma, a corona discharge or a flame treatment. The applied mixtures, which also contain photoinitiators, are dried and irradiated with electromagnetic waves using, as electromagnetic sources, lamp emitters having a wavelength in the range from 200 nm to 700 nm or electron emitters. With the UV / VIS radiation, a rapid curing of the mixed with the photoinitiators coating is to be made possible. These measures are to allow according to the introduction of description particularly well-adhering coatings compared to the known plasma, corona or flame treatments.

task The present invention is the adhesion between Coating and substrate / substrate with as possible simple means and short treatment times with gentle environmental impact to improve.

The Inventors have observed that for nonpolar and amorphous substrate surfaces often liability problems occurred. For example, was at Printed plastic films also observed that a well-toughened Coating simply by means of an adhesive strip from the surface of the carrier material could be deducted.

Surprisingly The adhesion was significantly improved when the substrate before the first coating or when a coated substrate before the first hardening a stationary electric Field was suspended. The intensity of the electric Feldes should be at least sufficient to be on the surface of the substrate or in the boundary layer between substrate and coating the charge carriers in the form of electron gases or of Align dipoles, the electric field preferably a Has inhomogeneous course between at least two electrodes. What is important is that a relative movement between substrate and electrical Field done. Due to the penetration and penetration of the electrical Field in the carrier material become the charge carriers on the surface and inside the substrate uniformly aligned so that the surface properties the carrier material for the adhesion of the coating and the subsequent curing are particularly well suited.

It is particularly advantageous when the course of the stationary electric field and the direction of movement of the charge carriers are directed opposite. It was found that Under these conditions, the substrate surface or the boundary layer between the coating and the substrate surface especially let it polarize easily.

The Stationary electric field is in a particularly simple Form designed as a stationary, electrostatic field, this is due to the application of a constant voltage to the electrodes results.

If the substrate is transported on a conveyor belt can the electrodes at a small horizontal distance from the substrate surface be adjusted so that the electric field lines in one curved course initially directed perpendicular to the substrate are and then substantially parallel to the substrate surface run, then again arcuate into the next Electrode to enter. Between the electrodes is a Dielectric, wherein the inhomogeneous course of the electric field by the geometric arrangement of the electrodes and the dielectric being affected. The electrodes are usually elongate designed, which are arranged transversely to the transport direction. It is but also possible, along the transport direction to align the electrodes, with several web widths Electrodes are used.

By Experiments found that the voltage between the electrodes preferably in a range greater than 600 volts, especially greater than 1000 volts. For example Can the electrodes at a distance of one centimeter be arranged, wherein the distance to the substrate surface between 0.5 and 1 cm. The transport speed of the substrate should preferably be 1 to 10 m / sec. Since it is according to the invention only a relative movement between the substrate and the electric field arrives, In principle, it is also possible that the electric field is moved while the substrate is fixed in place. Another theoretical possibility is that both the electric field and the substrate in the same direction or be moved in opposite directions. Another option is the modulation of the voltage without changing the polarity.

in the The invention is based on an embodiment explained in more detail. Show it:

1 Process principle of the inventive production of coated with paints, varnishes or similar coatings substrates

2 : Basic structure of a device according to the invention (partial)

3 : Variant of the device according to the invention (partial).

In 1 the two variants of the method according to the invention are shown, wherein in the variant 1 the untreated substrate is exposed to a stationary electric field, then, for example, provided with an application of paint, cured and optionally re-coated and cured.

The variant 2 shows the process, starting with the coating and then driving through the stationary electrostatic field.

The inventive device is fragmentary in 2a and on average in 2 B displayed. It is the basic structure of a polarization unit with two electrodes 1 . 2 and a dielectric disposed therebetween 3 shown, wherein between the electrodes 1 . 2 an arcuate course of the electric field can be seen.

Parts of the electric field, indicated by the field lines 4 , reach into the surface of the substrate 5 , wherein in the application example selected here already a coating 6 is provided.

Preferably in the area 7 of the electric field, in which the field lines the direction of movement 8th of the substrate 5 or the coating 6 In accordance with the invention, the charge carriers get into the influence of the electric field and cause orientation or polarization with the consequence of improved adhesion. The aim is that the charge carriers in the form of electrode gases or in the form of dipoles align in such a way that they provide an additional adhesion component for the charge carriers present in the coating.

In 3 is a fragmentary cross section through a railway application shown. Between two electrodes 1 . 2 passing through the airspace (dielectric 3 ) are separated, becomes the uncoated substrate 5 moved through. The field lines 4 run inhomogeneous and cross in the area 7 when penetrating the substrate 5 its direction of movement 8th ,

Of course the device according to the invention can also with three or more electrodes are equipped, resulting in a special spatial distribution of the stationary electric field. The direction of the Polarization changes with the orientation of the electrical Field or the field lines. Other influencing factors are form and material of the electrodes as well as the dielectric, applied Voltage, polarity of the electrodes and transport direction as well as transport speed of the substrate. For stationary field lines and moving Object changes when passing the electrodes of the force vector for the charge carriers on the object surface in amount and direction.

at an electrically conductive surface, the free Charge carrier separated by mechanical forces. Under the influence of the field forces migrate the free Charge carrier to the surface of the conductor and provide an additional liability component.

at a non-conductor, the charge carriers are firmly in the atomic or molecular structure bound. The field forces effect here a rotation of the charge carriers called polarization or dipoles, so here too on the surfaces of the nonconductor electric charges are disconnected. The aligned dipoles cause improved adhesion for the coating with lacquer coatings or printing inks.

1

First electrode

2

Second electrode

3

dielectric

4

field lines

5

substratum

6

coating

7

crossing area the field lines of the electric field

8th

movement direction of the substrate

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 69704860 T2 [0002]
• - DE 60303011 T2 [0005]

Claims (17)

Process for the production of coated with paints, varnishes or similar coatings substrates with increased adhesion or improved adhesion comprising - the application of at least a first layer to the substrate - the drying or curing of the layer - and optionally the application, drying and / or curing more Layers - wherein the substrate and / or the coating comprises charge carriers in the form of electron gases or of dipoles, characterized in that the substrate is subjected to a stationary electric field before the first coating or the coated substrate prior to the first curing, wherein on the surface of the substrate or act in the boundary layer between the substrate and coating forces on the charge carriers. Method according to claim 1, characterized in that that the coated substrate in a stationary electrostatic or electromagnetic field is moved. Method according to one of the preceding claims, characterized in that the electric field between at least two electrodes has an inhomogeneous course. Method according to one of the preceding claims, characterized in that between the electrodes, a dielectric is arranged and the electric field between the electrodes has a curved course. Method according to one of the preceding claims, characterized in that the coating on a bow or web-shaped substrate takes place. Method according to one of the preceding claims, characterized in that the arched or web-shaped Substrate made of single or multi-layered paper, plastic or Composite material exists. Method according to one of the preceding claims, characterized in that the course of the stationary electric field and the direction of movement of the charge carriers is directed the same and / or opposite. Method according to one of the preceding claims, characterized in that the course of the stationary electric field and the direction of movement of the charge carriers is aligned orthogonal to each other. Method according to one of the preceding claims, characterized in that the arched or web-shaped Substrate with paint, varnish or other coating material is printed. Method according to one of the preceding claims, characterized in that the coating with a UV-curing Color is done. Method according to one of the preceding claims, characterized in that the adhesion of the coating on the substrate by a changing by the transport movement electromagnetic, electrostatic or electric field improved becomes. Method according to one of the preceding claims, characterized in that the substrate surface or the boundary layer between the coating and the substrate surface is polarized, the direction of the polarization corresponding to the change of the alignment of the electric field lines changes during transport. Method according to one of the preceding claims, characterized in that the field lines of the electric field essentially alternately perpendicular and parallel to the surface of the coating material and at least partially in these penetrate. Method according to one of the preceding claims, characterized in that the voltage between the electrodes greater than 1000 V is. Apparatus for carrying out the method according to one of the preceding claims, characterized that before a first coating device or between a first coating device and a first curing device a static electric field between at least two electrodes is arranged inhomogeneous with respect to the coating, the field lines being up to the boundary between the substrate surface and extend the coating material. Device according to the preceding claim, characterized characterized in that a dielectric disposed between the electrodes is, wherein the course of forming between the electrodes Field lines in the form of a stationary but inhomogeneous Feldes done. Apparatus according to claim 15 or 16, characterized that between the electrodes an electrostatic field with a Potential difference of more than 600 V is present.