EP2319703B2 - Method for applying fluids in a grid pattern onto substrates - Google Patents

Description

The present invention relates to a method having the features of claim 1.

In the field of the production of printed products, it is already known that the products, which are preferably produced using offset printing, can be further optically refined, e.g. by so-called spot coatings. Furthermore, it is also already known to upgrade the products functionally, e.g. by applying lenticular foils to produce so-called wiggling images.

From the DE 103 60 050 B3 An offset printing process is known in which a substrate is first printed with oil-based offset printing ink, then coated with a transparent, oil-based matt varnish containing particulate matting agents and finally covered with a transparent, water-based gloss varnish, e.g. dispersion varnish. The matt coating is only applied to a partial area of the substrate, while the gloss coating is applied to the entire surface. Both the matt and the gloss varnish are applied without any screening and instead as homogeneous, isotropic coatings. Only the offset printing colors seem to be applied with a printing screen, as is usual in offset printing. The method described in the patent is known under the name "drip-off" and, according to the disclosure, leads to high-contrast matt-gloss effects.

The DE 10 2006 003 311 A1 describes a method for generating image effects that can be changed depending on the viewing angle, whereby first a lacquer grid (point grid or line grid) is applied to a full-area or only part of the base lacquer layer and then a UV lacquer is applied to the exposed areas of the base lacquer layer. The UV coating forms a lenticular functional layer and is then dried. Below the three layers mentioned is printing ink in a layer of ink applied by offset printing units and forms a multicolored print subject. In order to ensure the lenticular function of the UV varnish layer, it is necessary that the Grid of the second varnish or the correspondingly formed UV varnish is matched to a grid of the print subject. In other words: the lenticular grid of the image and the lenses must not be different.

In the EP 1 211 095 A1 describes a method for printing raised structures, in which the image is printed with a paint that drips off the paint laid over it, so that the paint collects at the edges of the colored stripes and forms raised lines there. In a similar way to the above DE 102006003311 A1 the grid of these structures follows the grid of the structures of the underlying color image.

Another method for producing relief-like structures on images printed using the offset process consists in applying powder, flakes, etc. to the offset ink while it is still wet, these powders sticking to the ink, and then the ink is allowed to dry completely. This procedure is in the U.S. Patent 46 84 548 described.

In addition, the market for high-quality printed products constantly requires new, optically appealing and/or functionally enhanced printed products or printed, optically appealing and/or functional features on conventional printed products.

Against this background, the object of the present invention is to create a method that is improved over the prior art, which makes it possible to produce optically appealing and/or functionally enhanced printed products in a simple manner and with known technical means, in particular quickly, inexpensively and in large quantities to achieve quantities of effect features on printed products or to imitate known effects of expensive features with corresponding effects of cheaper features.

According to the invention, these objects are achieved by a method having the features of claim 1 . Advantageous developments of the invention result from the associated dependent claims and from the description.

A method according to the invention for the rasterized application of fluids to substrates is a method in which - in case i) a substrate that is not rastered in at least one section or a coating of the substrate that is not rasterized in at least one section, a rasterized first image of a first fluid is applied using a first application device the substrate is applied in the section, the first fluid being a transparent varnish and the first image being applied as a continuous tone image having anisotropy, or in case ii) a substrate screened at least in the section or at least in the section of the rasterized coating of the substrate, a differently rasterized first image of a first fluid is applied to the substrate in the section, with both rasters having different raster shapes and/or raster sizes and/or raster spacing and/or raster angles, - an unrastered one covering the first image second image of a second fluid is applied using a second applicator to the substrate in the section which in case i) has a directional gloss due to the anisotropy of the first image, the second fluid being a transparent varnish - the formation of the second fluid on the substrate in the section is essentially determined by the grid of the first image in the section, with the second fluid beading off the first fluid and collecting at such points on the substrate or its coating and there the layer thickness of the second fluids that are not coated with the first fluid, - and the first image for the second fluid represents a latent, transparent wetting image.

The term "second image" also includes the homogeneous, isotropic application of the second fluid without information content, e.g. second fluid sprayed on in the form of a layer covering the entire area in the section. Due to the formation of the second fluid according to the raster (pattern) of the first fluid, the final structure can nevertheless carry information, e.g. a corresponding (preferably negative) pattern. However, the application can also be carried out partially in the section, e.g. in so-called spots or structured, e.g. in the form of a pattern.

According to the invention, in contrast to the prior art of the drip-off effect, a screened first fluid is applied. The grid of this first fluid is also not like in State of the art of the lenticular effect on an underlying grid (of the substrate or a substrate coating) tuned, but surprisingly chosen to be different. If the substrate or its coating is not screened, then of course there is no need to pay attention to the difference.

According to the invention, the second fluid forms according to the pattern of the first fluid, i.e. the second fluid collects at the points where the first fluid is not present. The second fluid does not wet the first fluid or wets it only poorly and therefore collects at the more easily wetted points where no first fluid is present, ie to a certain extent in the grid gaps on the substrate or its coating.

A grid of a second fluid is thus advantageously created according to the invention using a first fluid. Since this grid of second fluid is not matched to a grid of the substrate located underneath or its coating (except for the first fluid required for formation), no lenticular effect can occur. According to the invention, however, this is downright desirable, because the grid of second fluid should come from within itself (ie also on an unstructured, homogeneous, isotropic, monochromatic background) and without a lens interaction

(Refraction of light) produce at least an optical effect with the background. For example, this effect can be a direction-dependent gloss or an optical (light/dark) and/or tactile (high/low) perceptible pattern. Alternatively, this effect can be based on a locally changed reflection, colourfulness, transparency or scattering by the second fluid according to its rastering.

According to the invention, the first image represents a latent, transparent wetting image for the second fluid. The advantage here is that the first fluid influences the optically perceptible effects of the grid produced from the second fluid only through its grid, but not through its color. A color effect can thus be produced solely and undisturbed by coloring the second fluid. In this case, a wetting-changing fluid known from the production of the drip-off effect can be used as the first fluid, e.g the matt lacquer described in the prior art.

According to the invention, the second fluid is a transparent lacquer. In addition, it can be advantageous to select the second fluid colorless as well, thereby achieving essentially undisturbed gloss effects. In this case, an additional color effect or metal effect can be produced by a printed image underneath or cold foil transfer material forming the background. In this way, surfaces such as brushed steel or grinding and polishing patterns can be printed inexpensively. Alternatively, natural structures (fur, leather) or cracks can also be reproduced.

In case i), the first image is applied according to the invention as a halftone image. The advantage here is that the raster of the first fluid can be used to achieve effects that are rich in detail or have gradients. The first image can thus be structured like a graphic image and not only have coarse raster structures, as is sufficient for producing the lenticular image. The above-mentioned reproduction of detailed, natural structures can easily be achieved in this way.

In case i) according to the invention, the first image has an anisotropy, preferably due to the use of a line screen. As a result, the second image can have a direction-dependent gloss. In this context, it is particularly advantageous that a corresponding anisotropic structuring of the second fluid applied in an unstructured manner or only in spots can be achieved in a simple manner by the anisotropic pre-structuring by means of the first fluid.

An advantageous and therefore preferred development of the method according to the invention can be characterized in that the second fluid contains effect pigments (microparticles) that produce interference phenomena. All of the effects already mentioned can be reinforced or upgraded further by additionally using such effects of the pigments. In the case of the direction-dependent gloss mentioned, the superimposed effect of additional effect pigments can lead to a further upgrading of the product and, despite the simple printing technology production method, is too surprising appealing, complex effects.

An advantageous and therefore preferred development of the method according to the invention can be characterized in that a colored third fluid, preferably offset printing ink, or metallically shiny foil transfer material, preferably cold foil transfer material containing metal particles, is applied to the substrate before the first fluid. As already mentioned above, it can be advantageous to combine the color effect of an underlying image or the metallic luster of underlying cold foil transfer material with the raster effects according to the invention and thereby achieve even more enhanced optical effects, in particular those with a metallic appearance.

An advantageous and therefore preferred development of the method according to the invention can be characterized in that the first fluid is applied with a first printing form, with an offset printing form or a letterpress form preferably being used as the first printing form. A flexographic printing form can more preferably be used as the letterpress form.

An advantageous and therefore preferred development of the method according to the invention can be characterized in that the second fluid is applied with a second printing form or with a spray device.

An advantageous and therefore preferred development of the method according to the invention can be characterized in that a flexographic printing form, an offset printing form applying water-based paint, a gravure printing form or a screen printing form is preferably used as the second printing form. Application methods that can achieve a layer thickness sufficient for a formation are particularly advantageous.

The invention as such and constructively and/or functionally advantageous developments of the invention are described in more detail below with reference to the associated drawings using at least one preferred exemplary embodiment. In the drawings, corresponding elements are given the same reference numbers.

Fig. 1

einen Ablaufplan eines bevorzugten Ausführungsbeispiels eines erfindungsgemäßen Verfahrens, und

Fig. 2

einen Ablaufplan eines weiteren bevorzugten Ausführungsbeispiels eines erfindungsgemäßen Verfahrens.

The drawings show:

1

a flowchart of a preferred embodiment of a method according to the invention, and

2

a flowchart of a further preferred embodiment of a method according to the invention.

figure 1 shows a flow chart of a preferred embodiment of a method according to the invention for rasterized application of fluids onto substrates (according to case i in the claims). The left-hand side shows the method when an unscreened substrate 1 is provided, and the right-hand side when a substrate 1 with an unscreened coating 2 is provided. A section 3 is shown on both sides, in which the treatment, ie the application of fluid, essentially takes place.

In method step A, the substrate 1 or the substrate 1 is provided with a coating 2 for the subsequent method steps. The substrate 1 can be a printing material such as paper, cardboard or film. The coating 2 can be a homogeneous layer of paint or lacquer, e.g. monochromatic or colorless, or a homogeneously applied cold foil transfer material, e.g. shiny metallic. Process step A, as well as the subsequent process steps B to D, can be carried out in a printing press with a feeder, offset printing units, coating units, cold foil module, dryer and delivery (in the process corresponding sequential arrangement).

In method step B, a first fluid 5 is applied to the substrate 1 or to its coating 2 using a first application device 4 . The application device 4 can be a printing form, preferably an offset printing form. The first fluid 5 is a transparent paint. The first fluid 5 is applied as a screened first image 5', in case i) as a halftone image. The grid can be a point or line grid. The first fluid 5 has a property that means that in the subsequent method step C applied second fluid 6 wets the first fluid 5 less well than the substrate 1 or its coating 2. Preferably, the first fluid 5 has a lower surface energy than the substrate 1 or its coating 2. The first image 5' therefore represents a latent, transparent wetting image for the second fluid 6. The first fluid 5 can therefore be a wetting-changing fluid used in the known drip-off effect, such as an oil-based matt paint.

In method step C, a second fluid 6 is applied to the substrate 1 or to its coating 2 and also to the first fluid 5 using a second application device 7 . The application device 7 can be a printing form, preferably a flexographic printing form, or a spray device. The second fluid 6 is also a transparent paint. The second fluid 6 is applied as an unrastered second image 6', which covers the first image 5' at least in section 3 and there at least partially. The second fluid 6 forms a layer for a short time, which, however, is screened in the subsequent method step D by formation. Preferably, the second fluid 6 is applied wet-on-wet, i.e. before the first fluid 5 has substantially dried. A known, water-based gloss paint can also be used as the second fluid.

In method step D, a formation 8 of the second fluid 6 takes place on the substrate 1 or its coating 2 in section 3 . This formation 8 is essentially determined by the grid of the first image 5 ′ in section 3 . In the example shown, the second fluid 6 drips off the first fluid 5 and collects at those locations on the substrate 1 or its coating 2 that are not coated with the first fluid 5 . The layer thickness of the second fluid 6 increases at these points, so that optically and/or tactilely perceptible effects arise (the thickness can be increased further by using swelling lacquer). However, it is not necessary to achieve similar layer thicknesses as in the production of lenticular screens, since according to the invention no significant lens effect (refraction of light) is to be achieved. In case i), the first image 5' has anisotropy, preferably due to the use of a line screen, and as a result the second image 6` has a direction-dependent gloss. The second fluid 6 can additionally Contain effect pigments that produce interference phenomena and intensify the optical effect, in particular with a given direction-dependent gloss.

In other words: The second fluid 6 applied without a pattern experiences a formation on the substrate 1 or its coating 2 that is controlled or determined by the first fluid 5 applied in a pattern. but the second fluid 6 rolls off according to the predetermined and spatially resolved structure of the first fluid 5 and collects according to a negative structure. This formed structure is preferably so fine that optical effects such as direction-dependent gloss can arise and at the same time so coarse that sufficient second fluid 6 rolls off locally and collects locally. This also leads to a local accumulation of second fluid 6 and, as a result, to improved optical or even haptic/tactile effects.

figure 2 shows a flow chart of a further preferred embodiment of a method according to the invention for the rasterized application of fluids onto substrates (according to case ii in the claims). The left-hand side shows the method for providing a gridded substrate 1 and the right-hand side for providing a substrate 1 with a gridded coating 2 .

In method step A, the provision takes place accordingly figure 1 . The patterned substrate 1 can be an embossed substrate. The coating 2 can be a screened layer of paint or varnish or a cold foil transfer material that is applied in a screened manner and preferably has a metallic luster/containing metal particles. The grid can be a point or line grid.

In method step B, the first application of fluid takes place accordingly figure 1 . It is in figure 2 it can be clearly seen that the grid of the first fluid 5 is different from the underlying grid of the substrate 1 or from its coating 2 . The difference can be that both screens have different screen shapes and/or screen sizes and/or screen spacing and/or screen angles. The grid of the first fluid 5 can have dots, ellipses, stars or lines as grid shapes.

Thus, while care must be taken to ensure that the grids match when producing lenticular images, such a match is avoided according to the invention. This is because the final structure made from the second fluid 6 is not intended to serve as a lens grid for an image underneath (e.g. a shaky image), nor are pronounced moiré effects to arise due to poor matching. Rather, the final structure of the second fluid 6 should produce an effect itself, i.e. without any significant interaction with structures located underneath.

In method step C the second application of fluid takes place and in method step D the formation takes place accordingly figure 1 .

A printed product produced according to the invention in this way can comprise: a substrate 1, offset printing ink 2 and/or cold foil transfer material 2, screened, transparent, wetting-changing fluid 5 and transparent varnish 6 screened in substantially the same way. A feature produced according to the invention on an otherwise conventional printed product can be on the substrate 1 include: offset printing ink 2 and/or cold foil transfer material 2, rastered, transparent, wetting-changing fluid 5 and essentially the same rastered transparent varnish 6. Due to its optically and haptically/tactilely appealing effect, such a feature can also be used as a so-called security feature, e.g. during verification for authenticity, find use. When using metallically shiny cold foil transfer material 2 as a background and the second fluid 6 admixed effect pigments, such as so-called iriodines, the feature appears similar to a hologram, although it is much simpler, cheaper and produced "inline" by printing with known technical means can be, ie it can be dispensed with a complex application (eg gluing).

Reference List

1

substrate

2

coating

3

Section

4

first application device

5

first fluid

5'

first picture

6'

second picture

7

second applicator

8th

formation

Claims (6)

1. Method for the halftone application of fluids to substrates,

   - wherein in a case i) of a substrate (1) that has at least one halftone-free section (3) or of a coating (2) of the substrate (1) that is halftone-free at least in the section (3), a first halftone image (5') of a first fluid (5) is applied to the substrate (1) in the section (3), wherein the first fluid (5) is a transparent varnish and the first image (5') is a halftone image with an anisotropy,
   or in a case ii) of a substrate (1) that has a halftone at least in the section (3) or of a coating (2) of the substrate (1) that has a halftone at least in the section (3) a first image (5') of a different halftone of a first fluid (5) is applied to the substrate (1) in the section (3), the two halftones having different halftone shapes and/or halftone sizes and/or halftone spacing and/or halftone angles,

   - wherein a halftone-free second image (6') of a second fluid (6) covering the first image (5') is applied to the section (3) on the substrate (1) by means of a second application device (7), the second image in the case i) having a direction-dependent gloss due to the anisotropy of the first image (5'), wherein the second fluid (6) is a transparent varnish,

   - wherein the formation (8) of the second fluid (6) on the substrate (1) in the section (3) is essentially determined by the halftone of the first image (5') in the section (3), the second fluid (6) rolling off the first fluid (5) and collecting in such places on the substrate (1) or the coating (2) thereof that are not coated with the first fluid (5) and increasing the layer thickness of the second fluid (6) in these places, and

   - wherein the first image (5') represents a latent transparent wetting image for the second fluid (6).
2. Method according to Claim 1,
   characterized in
   that the second fluid (6) includes accent pigments that create interference phenomena.
3. Method according to Claim 1,
   characterized in
   that before the first fluid (5), a coloured third fluid (2), preferably offset printing ink, or foil transfer material (2) with a metallic gloss, preferably cold-foil transfer material containing metal particles, is applied to the substrate (1).
4. Method according to Claim 1,
   characterized in
   that the first fluid (5) is applied by a first printing forme (4), the first printing forme (4) preferably being an offset printing forme or a relief printing forme.
5. Method according to Claim 4,
   characterized in
   that the second fluid (6) is applied by a second printing forme (7) or a spraying device (7).
6. Method according to Claim 5,
   characterized in
   that the second printing forme (7) is preferably a flexographic printing forme, an offset printing forme applying water-based varnish, a gravure printing forme, or a screen printing forme.

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