EP2279865A2 - Screen printing method for printing an object with a printed pattern - Google Patents

Abstract

The method involves providing an object (1) to be printed, where the object is provided with a curved surface (2). A compound layer is applied on a filter screen, and is dried. The filter screen is filled with a printing color (4) and/or paint (5) i.e. varnish. The printing color and/or paint are applied on the curved surface of the object with maximum height of 100 micrometers for generating a three-dimensional print motive (3). The printing color and/or paint are cured by irradiation with ultraviolet radiation.

Description

The invention relates to a screen printing method for printing an article with a print motif.

The printing of objects for applying information or decorating is known. For this purpose, a variety of printing processes have been developed in the past, which ensure the most uniform possible application of printing inks and / or paints to produce high-quality print motifs. Despite the variety of printing techniques, there is a constant desire on the part of the customer to further develop the known printing processes in order to achieve novel effects.

From the DE 691 10 763 T2 is a screen printing method for printing signs is known in which a thick ink jet is applied to a flat substrate surface to produce a three-dimensional effect. The ink sheet is applied either in overlap with an edge of a thin ink layer or directly applied as an edge without an ink layer on the substrate surface. Following this, the substrate surface and the entire print motif are covered with a film layer or a thick layer.

The invention has the object of developing a screen printing process such that in the printing of objects with a curved surface in a novel manner novel effects can be achieved.

This object is achieved by a screen printing method with the features of claim 1. With the screen printing process according to the invention For example, three-dimensional print motifs can be generated which, owing to their raised structure, achieve an effect that is both visually and haptically novel. For this purpose, the known screen printing process for the production of two-dimensional print motifs is modified and misappropriated so that print motifs with a maximum height of at least 100 microns can be applied to the curved surface of the object to be printed. Since a considerable amount of printing ink and / or varnish is required to produce the three-dimensional print motif, other printing processes are ruled out. By means of the screen-printing method, with a suitable choice of the fabric density of a screen fabric, a sufficient amount of print job, ie printing ink and / or paint, can be applied, whereby the printing ink or the paint must cure before bleeding. In order to ensure timely curing, the printing ink or lacquer has photoinitiators which initiate a polymerization process under the influence of ultraviolet radiation, so that the printing ink or the lacquer cures before bleeding. The high amount of applied ink or paint thus maintains its three-dimensional structure and does not extend to a two-dimensional print.

To apply a high amount of print job or ink and / or paint, the screen fabric is coated several times directly before the screen printing process, so that a sufficiently high column of ink and / or paint can be formed. As a result, a high degree of flexibility in generating three-dimensional print motifs is ensured in a simple manner. In particular, large-area three-dimensional print motifs with comparatively sharp contours can be produced as desired since a sufficient amount of printing ink and / or varnish can be provided, even if the screen fabric has a fabric density of at least 25 threads / cm, in particular of at least 30 threads / cm, in particular of at least 35 threads / cm and in particular of at least 40 threads / cm.

Before the screen printing process, a layer of ultraviolet radiation curable composition is applied to the screen fabric. Subsequently, the applied layer is between dried and applied to this at least one further layer of the composition and intermediately dried. The coating can be carried out at least twice, in particular at least three times and in particular at least four times in order to produce the desired height of the column of printing ink and / or lacquer. At the end of the coating process, a film is applied to the applied layers, which protects the applied layers in the region of the print motif to be printed from ultraviolet radiation. In the subsequent irradiation with ultraviolet radiation, the applied layers are cured in the area outside the print motif to be printed. However, due to the film, the area of the print motif remains sufficiently soft to remove the applied mass or layers in that area from the screen cloth, for example, by rinsing. In the subsequent screen printing significantly more ink and / or paint can be applied, since the column of ink and / or paint is increased due to the layer by layer mass significantly increased over a corresponding column in height of the filament thickness of the mesh. Conversely, three-dimensional print motifs with a certain maximum height can be applied comparatively finely and with sharp contours, since the amount of printing ink and / or varnish does not have to be provided by a reduction of the fabric density of the screen fabric, but a screen fabric with comparatively high fabric density is sufficient to provide the desired amount of printing ink and / or varnish.

In particular, curved surfaces, such as, for example, hollow cylindrical sleeves and / or containers of writing implements and / or cosmetic articles, can be printed with the three-dimensional print motif using the screen printing method. Since the printing ink or lacquer does not harden before being irradiated with ultraviolet radiation, a stable printing process, short changeover times and a long operating time of the printing press are ensured. Particularly suitable for printing curved surfaces are screen fabrics whose threads have a high thread thickness and / or are formed from a metallic material, since higher forces act on the threads when printing curved surfaces than when printing on flat surfaces.

The printing ink or the varnish can be based on synthetic resin and / or natural resin. In addition, the printing ink and / or the paint can be provided with pigments and / or effect additives, such as metal powder. Alternatively, the paint may be formed as a clear lacquer.

The object to be printed may have been embossed with an embossing foil before the application of the printing ink or the lacquer. The embossing film may be formed, for example, photoreal. This makes it possible to apply any images with a three-dimensional haptic and optical effect on the object.

A screen printing method according to claim 2 leads to an improved haptic effect. The printing ink and / or the varnish can with a maximum Height can be applied, which is adjustable in wide ranges. The three-dimensional print motif can have a maximum height of up to 2000 μm.

A screen printing method according to claim 3 prevents the bleeding of the printing ink and / or the paint before curing. The higher the viscosity of the printing ink and / or the paint, the higher the printing ink and / or the paint can be applied. This is particularly important when printing on curved surfaces, as these due to the curvature is given an increased tendency to bleed. Suitable thickeners are known and commercially available.

A screen printing method according to claim 4 prevents bleeding of the applied ink and / or the applied paint. The smaller the time interval between the application and the irradiation, the better the three-dimensional structure of the applied printing ink and / or of the applied paint is retained. This is particularly important when printing on curved surfaces, as these due to the curvature is given an increased tendency to bleed.

A screen printing method according to claim 5 ensures the application of a high amount of the printing ink and / or the paint. The fewer threads / cm the screen fabric has, the more ink and / or paint can be applied. In addition, the application of a high amount of the printing ink and / or the paint is ensured by the thread thickness of the threads. The larger the thread thickness, the more ink and / or varnish can be applied.

A screen printing method according to claim 6 enables the production of three-dimensional print motifs with a comparatively good resolution. Because a high column of printing ink and / or lacquer can be produced, it is also possible to use screen fabrics having a comparatively high fabric density, since the required quantity of printing ink and / or lacquer does not have to be provided exclusively via a low fabric density. Accordingly, three-dimensional print motifs of a certain height can be produced with a comparatively good resolution by increasing the fabric density with a high column of printing ink and / or varnish.

A screen printing method according to claim 7 allows the printing of cylindrical and / or hollow cylindrical objects, such as sleeves and / or containers of writing instruments and / or cosmetics.

A screen printing process according to claim 8 ensures rapid curing of the applied print motif, since the high amount of clear lacquer in the print job ensures high transparency of the print motif for the ultraviolet radiation. With a high amount of clear varnish, correspondingly high three-dimensional print motifs with sharp contours can be produced.

A screen printing method according to claim 9 ensures a rapid curing of the applied print motif, since the small amount of ink in the print job only slightly affects the transparency and curing, but at the same time gives the print motif a colorful appearance. The ink is preferably mixed with a high amount of clear varnish.

A screen printing method according to claim 10 prevents the bleeding of the printing ink and / or the paint before curing. The addition of solid particles increases the viscosity of the printing ink and / or the paint. At the same time, attractive optical and / or haptic effects can be generated by solid particles, in particular of metal or plastic.

A screen printing method according to claim 11 enables the production of high three-dimensional print motifs with appealing optical effects. The embossing film is preferably applied to clear lacquer, which can be applied with the screen printing process according to the invention as a high print motif. If the embossing foil is pressed onto the object and the applied clear lacquer at a low temperature, then the embossing foil adheres exclusively to the clear lacquer and dissolves again from the part of the article not provided with clear lacquer. As a result, novel optical and / or haptic effects can be generated.

Fig. 1

eine Seitenansicht eines mit einem dreidimensionalen Druckmotiv bedruckten Gegenstandes gemäß einem ersten Ausführungsbeispiel,

Fig. 2

eine Draufsicht auf die in einer Ebene dargestellte gekrümmte Oberfläche des Gegenstandes,

Fig. 3

eine teilweise geschnittene Seitenansicht des zu bedrucken- den Gegenstandes sowie eines Siebgewebes beim Siebdruck- vorgang,

Fig. 4

eine Seitenansicht eines mit einem dreidimensionalen Druck- motiv bedruckten Gegenstandes gemäß einem zweiten Aus- führungsbeispiel, und

Fig. 5

eine Seitenansicht eines mit einem dreidimensionalen Druck- motiv bedruckten und mit einer Prägefolie versehenen Ge- genstandes gemäß einem dritten Ausführungsbeispiel.

Further features, advantages and details of the invention will become apparent from the following description of several embodiments with reference to the drawings. Show it:

Fig. 1

a side view of an object printed with a three-dimensional print motif according to a first embodiment,

Fig. 2

a plan view of the in a plane illustrated curved surface of the object,

Fig. 3

2 a partially sectioned side view of the article to be printed and of a screen fabric during the screen printing process,

Fig. 4

a side view of an object printed with a three-dimensional print motif according to a second embodiment, and

Fig. 5

a side view of a printed with a three-dimensional print motif and provided with an embossing foil article according to a third embodiment.

Fig. 1 shows an article in the form of a hollow cylindrical sleeve 1, which is for example part of a writing utensil or a cosmetic article. The sleeve 1 has a circular cross-sectionally curved surface 2, on which a flower-like print motif 3 is arranged.

The print motif 3 is formed from a cured by ultraviolet radiation ink 4 and cured by ultraviolet radiation paint three-dimensional and has a maximum height H of at least 100 .mu.m, in particular of at least 500 .mu.m, in particular of at least 1000 .mu.m, in particular of at least 1300 microns and in particular of at least 1500 microns.

For curing the printing ink 4 and the paint 5 when irradiated with ultraviolet radiation, these are provided with photoinitiators 6, which initiate a polymerization process under the influence of ultraviolet radiation and cause the curing of the printing ink 4 and the paint 5. In addition, the ink 4 and the paint 5 on a thickening agent 7, which has increased the viscosity of the print job or the ink 4 and the paint 5 before curing.

The printing ink 4 and the varnish 5 are suitable for use in a screen printing process and are based, for example, on synthetic or natural resin. As the resin, for example, acrylate resin is suitable, which is contained in a proportion of 50 to 75 wt .-% in the printing ink 4 and the paint 5.

The three-dimensional print motif 3 is applied to the sleeve 1 by a screen printing method. For this purpose, the thickener 7 is first added to the printing ink 4 and the paint 5 prior to application, so that the viscosity of the printing ink 4 or of the paint 5 is at least 12,000 mPas, in particular at least 18,000 mPas, in particular at least 24,000 mPas, and in particular at least 30,000 mPas increased at 25 ° C. The printing ink 4 and the paint 5 are then applied through a screen fabric 8 at the desired locations on the sleeve 1, so that the print motif 3 is formed. The screen fabric 8 is for example in Fig. 2 indicated.

The screen fabric 8 is formed by a plurality of threads 9 which are spaced apart from each other and disposed on a frame 10 in a first direction and in a second direction perpendicular thereto. The screen fabric 8 is repeatedly coated directly to apply a large amount of ink 4 or paint 5 before the screen printing process, so that a sufficiently high column of ink 4 or paint 5 can be formed. For this purpose, the screen fabric 8 is coated with a first layer 11 of an ultraviolet radiation-curable composition. Subsequently, the applied layer 11 is between dried and applied to this another layer 12 of the mass. The coating can be carried out at least twice, in particular at least three times and in particular at least four times. At the end of the coating process, a film is applied to the applied layers 11, 12, which protects the applied layers 11, 12 in the region of the print motif 3 to be printed from ultraviolet radiation. During the subsequent irradiation with ultraviolet radiation, the layers 11, 12 are cured. Due to the film, however, the area of the print motif 3 to be printed remains sufficiently soft to remove the applied mass in this area from the screen cloth 8, for example by rinsing. This results in the area of the print motif 3, a receiving space 13 which is bounded laterally by the layers 11, 12. Significantly more printing ink 4 or paint 5 can be applied in the subsequent screen printing process since in the receiving space 13 the paint or lacquer column is markedly increased in comparison with a paint or lacquer column in the amount of the thread thickness due to the composition applied in layers.

For applying a sufficient amount of the printing ink 4 and the paint 5, the screen fabric 8 has a fabric density of at most 200 threads / cm, in particular of at most 120 threads / cm, in particular of at most 100 threads / cm, in particular of at most 40 threads / cm and in particular of at most 20 threads / cm. The fabric density may be varied within a range of 15 to 200 threads / cm depending on the required amount of the printing ink 4 to be applied and the paint 5 to be applied. For producing the print motif 3 with good resolution, the screen cloth 8 preferably has a fabric density of at least 25 threads / cm, in particular of at least 30 threads / cm, in particular of at least 35 threads / cm and in particular of at least 40 threads / cm on. In addition, the thread thickness of the threads 9 can be varied depending on the required quantity of the applied printing ink 4 and the paint 5 to be applied. In addition, the print motif 3 can also be built up in layers. For this purpose, the printing ink 4 or the paint 5 is applied in layers and cured.

For printing on the sleeve 1, this is placed on both sides at the end on two rotatably mounted rollers 14, 15. The rollers 14, 15 are transversely displaceable to the screen fabric 8, so that the sleeve 1 with its surface 2 against the threads 9 can be pressed. If the sleeve 1 against the screen fabric 8, a scraper 16 is disposed on the layer 12 and the screen fabric 8 relative to the scraper 16 and the sleeve 1 so linearly displaced in the horizontal direction, that the sleeve 1 rolls along the screen fabric 8. When unrolling, the scraper 16 presses the ink 4 located in the receiving space 13 or the paint 5 in the area of the printing motif 3 through the screen cloth 8 onto the surface 2 of the sleeve 1.

The printing ink 4 and the paint 5 are applied through the screen cloth 8 and then cured by irradiation with ultraviolet radiation. The time interval between the application and irradiation of the printing ink 4 and of the varnish 5 is at most 180 seconds, in particular at most 45 seconds, and in particular at most 20 seconds. The ink 4 and the varnish 5 do not run due to their viscosity and the time between application and irradiation, so that the cured print motif 3 has substantially the same height H with which it was applied. The print motif 3 is applied in particular with a height H of at least 500 μm, in particular of at least 1000 μm, and in particular of at least 1300 μm and in particular of at least 1500 μm.

The printing motif 3 has, for example, at least 70% by weight, in particular at least 80% by weight and in particular at least 90% by weight, of clear lacquer 5. Furthermore, the printing motif 3, for example, at most 20 wt .-%, in particular at most 15 wt .-% and in particular at most 10 wt .-% ink 4. By a high amount of clear varnish 5 and a comparatively small amount of ink 4 in the print job a rapid curing of the print motif 3 is ensured, this appears colored at the same time.

In the sleeve 1 according to Fig. 4 For example, the print motif 3 has solid particles 17 which increase the viscosity of the printing ink 4 and / or of the varnish 5 and at the same time produce an appealing visual and haptic effect. The solid particles 17 are, for example, pigments and / or effect additives. The solid particles 17 are in particular a metal powder.

The sleeve 1 according to Fig. 5 has a print motif 3 with an additional stamping foil 18. The raised structure of the print motif 3 consists of a clear lacquer 5. After curing of the clear lacquer 5, the embossing foil 18 is pressed against the surface 2 of the sleeve 1 and the clear lacquer 5 at a sufficiently low temperature. Due to the low temperature, the embossing foil 18 remains adhering substantially exclusively to the clear lacquer 5, whereas the embossing foil 18 does not adhere to the surface 2. The temperature is for example less than 300 ° C, in particular less than 250 ° C and in particular less than 200 ° C. The raised structure of clear lacquer 5 and the embossing foil 18 applied thereto can be used to produce novel optical and / or haptic effects.

Claims (11)

Screen printing process for printing an article with a print motif, comprising the steps of: Providing an article to be printed (1), in particular a writing utensil or a cosmetic article, the article to be printed (1) having a curved surface (2), Applying a layer (11) of an ultraviolet-curable composition to a screen fabric (8), Drying the applied layer (11), Applying and drying at least one further layer (12) of the ultraviolet radiation-curable composition, Applying a film to the applied layers (11, 12) which protects them from ultraviolet radiation in the region of a print motif (3) to be printed, Irradiating the film with ultraviolet radiation, wherein the applied layers (11, 12) harden in the region outside the print motif (3), Removing the film and the applied layers (11, 12) in the region of the print motif (3), Filling the screening fabric (8) with an ultraviolet-curable printing ink (4) and / or an ultraviolet-curable coating (5), - Applying the ultraviolet radiation curable ink (4) and / or the curable by ultraviolet radiation paint (5) on the curved surface (2) of the article (1) with a maximum height (H) of at least 100 microns to produce of the three-dimensional print motif (3), and - Hardening of the applied ink (4) and / or the applied paint (5) by irradiation with ultraviolet radiation. Screen printing method according to claim 1, characterized in that the printing ink (4) and / or the paint (5) having a maximum height (H) of at least 500 .mu.m, in particular of at least 1000 .mu.m, in particular of at least 1300 .mu.m and in particular of at least 1500th μm is applied. Screen printing method according to claim 1 or 2, characterized in that the viscosity of the printing ink (4) and / or the paint (5) prior to application by adding a thickening agent (7) to at least 12,000 mPas, in particular at least 18,000 mPas, in particular at least 24,000 mPas , And in particular at least 30,000 mPas at 25 ° C is increased. Screen printing method according to one of claims 1 to 3, characterized in that the time interval between the application and irradiation of the printing ink (4) and / or the paint (5) at most 180 seconds, in particular at most 90 seconds, in particular at most 45 seconds, and in particular at most 20 seconds. Screen printing method according to one of claims 1 to 4, characterized in that the screen printing fabric (8) for applying the printing ink (4) and / or the paint (5) has a fabric density of at most 200 threads / cm, in particular of at most 120 threads / cm, in particular of at most 100 threads / cm, in particular of at most 40 threads / cm and in particular of at most 20 threads / cm. Screen printing method according to one of claims 1 to 5, characterized in that the screen fabric (8) for applying the printing ink (4) and / or the paint (5) has a fabric density of at least 25 threads / cm, in particular of at least 30 threads / cm, in particular of at least 35 threads / cm and in particular of at least 40 threads / cm. Screen printing method according to one of claims 1 to 6, characterized in that the object (1) has a circular cross-sectionally curved surface (2). Screen printing method according to one of claims 1 to 7, characterized in that the article (1) with at least 70 wt .-% clear lacquer (5), in particular at least 80 wt .-% clear lacquer (5) and in particular at least 90 wt .-% clear lacquer (5) is printed. Screen printing method according to one of claims 1 to 8, characterized in that the article (1) with at most 20 wt .-% printing ink (4), in particular with at most 15 wt .-% printing ink (4) and in particular with at most 10 wt. % Printing ink (4) is printed. Screen printing method according to one of claims 1 to 9, characterized in that the printing ink (4) and / or the paint (5) solid particles (17) are mixed. Screen printing method according to one of claims 1 to 9, characterized in that on the cured printing ink (4) and / or the cured lacquer (5), in particular the cured clear lacquer (5), an embossing foil (18) is applied, the embossing foil (18) being pressed against the object (1) with such a low temperature that it adheres exclusively to the printing motif (3).

Images