CN114103505A

CN114103505A - Extinction by means of a transfer process

Info

Publication number: CN114103505A
Application number: CN202110993632.2A
Authority: CN
Inventors: M·施米特-莱文; H·古特; T·奥伊勒
Original assignee: Heidelberger Druckmaschinen AG
Current assignee: Heidelberger Druckmaschinen AG
Priority date: 2020-08-28
Filing date: 2021-08-27
Publication date: 2022-03-01
Also published as: EP3960462A1; EP3960463A1

Abstract

The invention relates to a method for applying a matting fluid layer (9) to a print substrate (6) by means of a stamp (3), wherein the matting fluid layer (9) is dried on the stamp (3) before being applied to the print substrate (6), characterized in that the matting degree of the applied fluid layer (9) is modified by means of parameters of the drying process and by means of surface properties of the stamp (3).

Description

Extinction by means of a transfer process

Technical Field

The invention discloses a method for applying a thin layer of matting fluid through a stamp onto a substrate in a targeted matting controlled manner.

The invention belongs to the technical field of printing (especially packaging printing and small-batch printing).

Background

When printing by means of the film transfer process (filmtransferpromezess), certain phenomena occur, in particular dullness/dullness (mattierun) of the glossy gloss oil during film transfer. The matting of the gloss varnish is independent of the substrate used and can (depending on the process parameters) take on different forms of expression and vary in strength.

In this case, matting varnish-varnishing (Mattlack-Lackiering) with the aid of water-based varnish (especially in packaging printing and in small-lot printing) is carried out in the prior art by means of two approaches. One variant is the addition of matting agents (i.e. additives) which, for example, roughen the surface, wherein, on the one hand, the printability (in the form of gloss oil viscosity) is changed and therefore reconciled separately, and, on the other hand, the volume addition of matting agents is limited and therefore the degree of matting is also limited.

A further variant is the use of stamps (druckfonn) which, by means of their surface structure/texture, achieve a matting of the varnish. In this case, the achievable extinction is form-bound and is partially dependent on the production method of the stamp, so that the targeted setting of the extinction effect can only be carried out conditionally. However, particularly good matting-glossing oils need to meet certain optical requirements, which can be achieved mainly by a defined surface roughness/matting.

However, when the fillers/additives (i.e. matting agents) are mixed, the viscosity of the varnish composition changes, so that it must be adapted again for printing. Depending on the printing method, further measures can be taken, for example, to select a suitable anilox roller (with regard to the draw volume, mesh type and size) and to circulate the varnish continuously in order to prevent the deposition of matting agent.

Disclosure of Invention

The object of the present invention is therefore to find a method for the targeted variation of the matting effect in various printing processes.

The object is achieved by a method for applying a matting fluid layer to a print substrate via a stamp, wherein the matting fluid layer is dried on the stamp before being applied to the print substrate, characterized in that the degree of matting of the applied fluid layer is changed by means of parameters of the drying process and surface properties of the stamp. By the targeted combination of the two possibilities of modification of the drying parameters and the stamp surface, the desired degree of extinction can be set more precisely than with the prior art methods.

Advantageous and therefore preferred embodiments of the method according to the invention result from the dependent claims and the description with the figures.

In a preferred embodiment, the matting fluid layer is a gloss oil layer or a pigment layer. In a particularly preferred embodiment, the matting fluid layer is a diffusion bright oil layer (dispersionsackschicht). In a very particularly preferred embodiment, the matting fluid layer is a spreading varnish layer of a varnish.

In this case, a further preferred development of the method according to the invention is that the parameters of the drying process include the drying power caused by the hot air supply. The drying power is the most important parameter. Preferably, the drying power is realized and quantified by a hot air supply. In a preferred embodiment, the hot air supply is effected in a strongly concentrated manner (in particular by means of slot nozzles). The important parameters are the increased volume flow of air and the increased temperature of the air.

The extinction of the applied fluid layer is changed by means of the method according to the invention. According to the invention, the matting fluid layer is dried on the stamp before application to the substrate. It has turned out that it is particularly advantageous to overdry the applied fluid layer in order to change the degree of matting. This means that the applied fluid layer dries more strongly than may normally be necessary. Suitable measures for this are, in particular: drying at elevated temperatures, longer drying durations, more intensive hot air supply, and combinations of these measures.

It has been shown that a stronger drying is particularly advantageous for the method according to the invention than is required in order to achieve a substantially completely dried-through (durchgetercken) fluid layer on the stamp.

In a preferred embodiment, the matting fluid layer is dried on the stamp prior to application to the substrate at a temperature above the drying temperature of the fluid used. The degree of extinction can be set particularly advantageously thereby.

The temperature range for drying is preferably in the range from 30 ℃ to 300 ℃, particularly preferably in the range from 50 ℃ to 100 ℃.

In this case, a further preferred development of the method according to the invention consists in that the applied fluid layer is dried on the stamp by means of a heat input (angelocknet) and the final drying/final drying (endlocknut) of the fluid film after transfer onto the print substrate takes place without further heat input. Since the partial drying is already carried out before the transfer onto the printing substrate, no further active heat source is required for the final drying remaining after the transfer.

In this case, a further preferred development of the method according to the invention consists in varying the roughness and/or the surface area of the stamp surface

Or point-like

The form of the stamp and/or the choice of material of the stamp to alter the surface properties of the stamp. Which variant is chosen depends on the desired properties. The combination of these three variants improves the accuracy of the desired degree of extinction.

In this case, a further preferred development of the method according to the invention consists in integrating test strips (kontrol treifen) made of different microstructures in the stamp for adjusting the parameters of the drying process and for adjusting the surface properties of the stamp, which different microstructures provide information in the form of a print about the current process and about the achievable print quality. Likewise, such test strips output a "printed image" on the fluid onto the substrate and can be evaluated similarly to color test strips.

In this case, a further preferred development of the method according to the invention consists in that the matting fluid layer is applied to the stamp by a gloss metering unit (in particular an anilox roller) or a digital printing system (in particular an inkjet print head). The difference here is not equivalent to the use of a corresponding printing press. Although not always advantageous, it is entirely possible to use an inkjet metering unit for applying the fluid in an offset printing press and, vice versa, a varnish metering unit with an anilox roller in an inkjet printing press.

Drawings

The invention itself and a structurally and/or functionally advantageous development of the invention will be explained in more detail below with reference to the attached drawings, according to at least one preferred embodiment. In the drawings, elements corresponding to each other are provided with the same reference numerals, respectively. The drawing shows that:

figure 1 shows a schematic configuration when applying a fluid by means of an anilox roller,

figure 2 shows a schematic configuration when applying a fluid by means of an ink jet unit,

fig. 3 shows a flow of a method according to the invention.

Detailed Description

Fig. 3 schematically shows a flow of the method according to the invention. In a first step, a fluid 9 (in most cases a varnish or pigment) is metered onto the stamp 3, which stamp 3 can be applied over the entire surface or in a punctiform manner, wherein this metering can be carried out conventionally or digitally. The fluid 9 applied to the stamp 3 is dried by heat input before being transferred to the substrate 6. The resulting fluid film 9 is then transferred to the substrate 6 in a solidified state.

The achievable extinction of the applied varnish layer can be influenced (or set) by two parameters during the printing process. On the one hand, the achievable matting can be set by the degree of drying before the film is transferred (i.e. by the choice of the drying parameters). On the other hand, the extinction of the varnish layer can be further influenced by using a stamp 3 with a rough surface, which stamp 3 is either full-surface or punctiform. By means of this rough surface, the fluid film 9 is conditioned (kondationier) when dry in such a way that a matting effect occurs on the printed product 10. The regulating variables mentioned here can also be combined arbitrarily.

In order to continuously check the process with regard to the achievable quality of the extinction effect and to coordinate the process parameters, test strips (similar to printed test strips) are integrated on the stamp 3. The test strip is composed of different microstructures which provide information in the form of a print about the current process and about the achievable print quality. These microstructures are used as test elements in the light-extinction method, and the production of a stamp 3 having such microstructures can be based on stamps 3 known from the prior art, for example stamp 3 described in DE 102014222677 a 1.

The method steps described in the present invention can also be divided into three phases:

stage 1: the metering of the fluid 9 onto the stamp 3 takes place, for example, by means of an anilox roll 1, as in flexographic printing,

and (2) stage: the applied fluid 9 is dried on the stamp 3 by a heat input (preferably by a hot air supply via a drying nozzle),

and (3) stage: the dried fluid film 9 is transferred to the substrate 6.

The final drying of the fluid film 9 on the substrate 6 is preferably carried out without further energy supply. The stamp 3 is made of a suitable material, such as silicone, and has a rough surface which has a direct influence on the luminosity. Furthermore, a test element is integrated on the stamp 3, which test element serves to ensure quality. Fig. 1 schematically shows the configuration of the system when applying a fluid 9 by means of an anilox roller 1. Additional components of the system include: a coloring unit 2, a drying unit 4, a drive device 5 for web transport of a printing substrate 6, and a cleaning unit 7.

The preferred application of the present invention is to utilize patterns, such as matte-finish, frosting effects, etc., in packaging printing and small lot printing as a finishing process.

An alternative method according to the invention involves using a further gloss metering unit 11 instead of the anilox roller 1. In particular, a digital printing system 11, for example an inkjet printing head 11, can be used for applying the fluid 9. That is to say, a clear ink is used as varnish, which is transferred in terms of its matting effect by means of the transfer process described above by means of a textured transfer tool in combination with an intermediate heat treatment onto the carrier material (for example the graphic print substrate 6) or the technical surface. For this purpose, fig. 2 shows the application of the fluid 9 by means of an ink jet unit 11.

Further alternative embodiments according to the invention relate in particular to alternative applications of such a varnish layer, for example:

the porous layer is produced, for example, as an absorbent, which absorbs moisture from the pores close to the surface, and in the case of a high heat input, bubbles are partially formed in the varnish, which thus produce porosity.

Applying a matt or porous layer to a film substrate (folliensktrat), wherein the applied layer can perform the function of an optical diffuser in combination with a transparent film ("frosted glass").

Application of a matt layer onto a transparent substrate (e.g. a film) in a technical manner for so-called light trapping (application of a functional layer) in the field of optical systems, in particular photovoltaics.

Alternative fluid/gloss systems:

-hybrid solution approach: a mixed gloss oil is used in order to produce a matt in a first step by evaporation of the aqueous component and subsequently to fix it during the UV hardening process and to set up the matt-polishing effect.

The options for use in the machine mainly relate to:

-a sheet-printing press,

-a web-fed printing press,

-a coating machine.

The method according to the invention for applying a thin matting fluid layer 9 to a substrate 6 has various advantages in this context, wherein fluid transfer in the sense of the method means: the fluid that has solidified is transferred to the substrate 6. The method is particularly stable with regard to the application of thin layers, since less drying power is required. If the stamp 3 is used in combination for the matting effect, no additional energy input is even necessary inside the printing press.

The invention makes it possible to apply particularly thin layers, either in full-surface or in dot-surface fashion, and to achieve targeted matting without the addition of matting additives or fillers. This process is carried out by metering a fluid film 9 onto the stamp 3, drying it on the stamp 3 by a defined heat input in a second step by the drying unit 4, and transferring it onto the substrate 6 in a third step. The extinction can be set by two independent process parameters (drying power and stamp design). If the extinction 10 is realized primarily by the stamp 3, it is additionally possible to realize different (optionally point-wise) extinction effects 10 on the page.

Compared to the prior art DE 102014222677, the invention does not require a conventional/special molding process involving the surface of the stamp 3, but rather involves more general transfer printing with changes caused, inter alia, by the (thermal) parameters of drying, which changes contribute to the change in the gloss oil that acts as a matte.

Naturally, the rough surface texture of the stamp 3 also has an influence on the extinction 10, but the surface texture only indirectly influences the extinction.

List of reference numerals

1 metering unit

2 coloring unit

3 impression die

4 drying unit

5 drive device for web transport

6 substrate for printing

7 cleaning unit

8 anilox roller

9 fluid

10 matted printed product

11 digital metering unit (ink jet)

Claims

1. A method for applying a layer (9) of a matting fluid through a stamp (3) onto a substrate (6),

wherein the matting fluid layer (9) is dried on the stamp (3) before being applied to the substrate (6),

it is characterized in that the preparation method is characterized in that,

the degree of extinction of the applied fluid layer (9) is modified by the parameters of the drying process and by the surface properties of the stamp (3).

2. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

the matting fluid layer (9) is dried on the stamp (3) at a temperature above the drying temperature of the fluid used before application to the substrate (6).

3. The method according to any one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the matting fluid layer (9) dries more strongly on the stamp (3) before application to the substrate (6) than is necessary to achieve a fluid layer that dries out substantially completely on the stamp (3).

4. The method according to any one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the matting fluid layer (9) is a layer of gloss oil or a layer of pigment.

5. The method according to any one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the matting fluid layer (9) is a diffusion-type varnish layer.

6. The method according to any one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the matting fluid layer (9) is a spreading varnish layer of varnish.

7. The method according to any one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the parameters of the drying process include the drying power caused by the hot air supply.

8. The method according to any one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

drying the applied fluid layer (9) on the stamp (3) by heat input, and

the final drying of the fluid film (9) on the printing substrate (6) after the transfer is effected without further heat input.

9. The method according to any one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the surface properties of the stamp (3) are changed by the variable roughness and/or the full-surface or punctiform form of the stamp surface and/or by the choice of the material of the stamp (3).

10. The method according to any one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

in order to adjust the parameters of the drying process and the surface properties of the stamp (3), test strips consisting of different microstructures are integrated into the stamp (3), said different microstructures providing information in printed form about the current process and about the achievable printing quality.

11. The method according to any one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the matting fluid layer (9) is applied to the printing substrate (6) by a gloss metering unit (1, 11), in particular an anilox roller (1), or by a digital printing system (11), in particular an inkjet printing head (11).