Method for manufacturing mechanically robust coating containing colorant
By enriching the hardenable liquid medium of floating pigments at the interface and connecting it with the substrate in the printing press, the mechanical stability problem of floating pigment coatings is solved, achieving efficient and economical coating manufacturing while maintaining visual effects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HEIDELBERGER DRUCKMASCHINEN AG
- Filing Date
- 2022-08-09
- Publication Date
- 2026-05-12
AI Technical Summary
Existing technologies struggle to efficiently manufacture mechanically stable coatings with floating pigments, and require additional protective layers to prevent wear, resulting in complex and uneconomical processes.
By applying a hardenable liquid medium containing floating pigments to a carrier, which is then dried and enriched at the interface and bonded to the substrate, a mechanically stable coating is formed, avoiding the need for an additional protective layer. Enrichment is achieved by utilizing the surface properties and density differences of the colorant at the interface.
It enables the efficient production of coatings with floating pigments in printing presses, which are highly abrasion resistant and visually appealing, requiring no additional protective layer and simplifying the process.
Smart Images
Figure CN115870191B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for manufacturing a coating having at least one colorant enriched at an interface, and to using the method to manufacture an abrasion-resistant coating containing such colorant. The invention also relates to printed matter obtained by the method of the invention. Background Technology
[0002] Various methods have been disclosed in the printing industry for applying visually appealing metallic finishes to printed materials. A common practice is, for example, applying a glossy foil using foil transfer printing. Another known possibility is to directly print pigment-containing printing inks or varnishes onto the substrate, followed by curing the printed substrate in a printing press. Offset printing is known as a method for this purpose.
[0003] Printing inks and varnishes containing effect pigments are disclosed in the prior art. These are, in principle, categorized into printing inks and varnishes with leafing pigments and those without leafing pigments. Generally, printing inks and varnishes with leafing pigments are considered to produce the most visually appealing metallic effects. Therefore, silver varnishes containing aluminum-based leafing pigments are popular. Such leafing pigments are described, for example, in the German Industrial Standard DIN 55923. In contrast, while printing inks and varnishes based on non-leaving pigments are becoming increasingly widespread, they typically exhibit a less visually appealing metallic effect and tend to appear rather matte and dull.
[0004] While printing inks and varnishes based on floating pigments exhibit excellent metallic effects, they have significant drawbacks. They suffer from problems with mechanical stability, particularly scratch sensitivity and abrasion resistance. Because the floating pigment lies beneath the surface, this coating is sensitive and typically requires protection from mechanical abrasion by one or more layers of varnish over it. However, applying this additional protective layer is laborious and uneconomical. In contrast, coatings based on printing inks and varnishes with non-floating pigments are generally less sensitive because the pigment is distributed essentially uniformly there. Here, an additional protective layer is usually unnecessary.
[0005] There is a need for efficient methods to produce mechanically stable coatings with floating pigments. Therefore, there is a need in the printing industry for methods to efficiently produce such mechanically stable coatings in printing presses.
[0006] EP 3 165 578A1 describes a metallic offset printing ink and printing method with a mirror finish. The abrasion stability of the aluminum pigment should be achieved through the printed layers.
[0007] WO 2008 / 052645 A2 describes a finishing method and coating unit for printed products. In this method, a liquid printing medium is applied to a carrier in a printing press, dried there, and transferred to a substrate. Summary of the Invention
[0008] The objective of this invention is to provide a method for efficiently manufacturing mechanically stable coatings with floating pigments. This method is particularly suitable for producing coated printed matter in a printing press.
[0009] Now, surprisingly, it has been found that a mechanically stable coating with floating pigments can be manufactured relatively simply by first applying a hardenable liquid medium containing floating pigments to a carrier, drying it there, and then attaching it as a thin film to the substrate to be coated using the side enriched with floating pigments. This method keeps the sensitive floating pigments away from the outer surface of the coated substrate and protects them with the hardened layer on top of them.
[0010] The method of this invention has many advantages. It eliminates the need to apply one or more protective layers. It eliminates the need to ensure compatibility between the pigment layer and the protective layer. The method can be implemented continuously in a printing press and is compatible with common printing inks, varnishes, and substrates.
[0011] Accordingly, the present invention relates to a method for manufacturing a coating having at least one colorant enriched at an interface, the method comprising the following steps:
[0012] i) Provide a hardenable liquid medium comprising at least one colorant enriched at the interface;
[0013] ii) Applying the curable liquid medium to a carrier, wherein the colorant enriched at the interface is enriched at the interface between the curable liquid medium and the surrounding ambient atmosphere.
[0014] iii) Harden the hardenable liquid medium at least partially on the carrier; and
[0015] iv) Transferring at least partially hardenable hardenable liquid medium from the carrier to the substrate, such that the side of the colorant enriched at the interface on the carrier adheres to the substrate.
[0016] In a preferred embodiment, the at least one colorant enriched at the interface is enriched in the curable liquid medium at the interface between the curable liquid medium and the ambient atmosphere due to its lower density and / or surface properties compared to the curable liquid medium. Here, the ambient atmosphere should be understood as, for example, the air atmosphere surrounding a printing plant.
[0017] In a particularly preferred embodiment, the colorant enriched at the interface is interfacially active (or surface-active) due to its surface properties. Here, the surface properties of the colorant enriched at the interface can also be altered through functionalization, for example, by coating with an interfacially active compound, such as stearic acid. Different surface energies are particularly important when the colorant is enriched at the interface due to its surface properties.
[0018] In another preferred embodiment, the at least one colorant enriched at the interface is at least one mechanically sensitive pigment. This particularly includes pigments that can be damaged or destroyed by relatively small external forces. An example of such relatively small external forces is a person holding a cardboard package, such as a cosmetic product, coated with the present invention. In contrast, purely heat-sensitive pigments tend to play a less important or subordinate role.
[0019] In another preferred embodiment, the at least one colorant enriched at the interface is at least one effect pigment. Particularly preferably, the at least one colorant enriched at the interface is at least one inorganic pigment, and very particularly preferably, at least one inorganic metallic effect pigment.
[0020] In another preferred embodiment, the at least one colorant enriched at the interface is at least one floating pigment.
[0021] In another preferred embodiment, the curable liquid medium is substantially transparent. Thus, the article obtained by the method of the present invention can also retain the visually attractive effect of the colorant used through a relatively thick layer of the cured curable liquid medium.
[0022] In another preferred embodiment, the method of the invention is carried out using a printing press, particularly in at least one printing mechanism, at least one varnishing mechanism, or a combination thereof. In this embodiment, the carrier is preferably a printing press cylinder or a plate (or printing plate) in the printing press, especially preferably a printing press cylinder. In this embodiment, UV-curable printing ink or UV-curable printing varnish is preferably applied to the cylinder of the preferred printing press using a cavity doctor blade having an anilox roller or roller mechanism. The application of the UV-curable printing ink or UV-curable printing varnish can also be carried out by spraying it onto the printing press cylinder using one or more nozzles. The UV-curable printing ink or UV-curable printing varnish on the cylinder of the preferred printing press is then cured by UV radiation, resulting in a sufficiently cured, transferable film. This at least partially cured film is then transferred from the cylinder serving as the carrier to a substrate, preferably paper, paperboard, or plastic foil, during the printing interval of the printing mechanism or varnishing mechanism of the printing press. To improve the adhesion of a liquid curable medium, which is at least partially hardened, to a substrate as a thin film, it is possible to apply an auxiliary adhesive layer to the substrate or the hardened liquid curable medium, for example, by means of spraying through one or more nozzles or by contact with an additional printing press roller for delivering adhesive from an adhesive container, before transferring the film.
[0023] The method of the present invention is preferably carried out using a printing press, wherein in principle all known printing methods can be employed. Preferred printing methods include web printing, digital printing, pad printing, indirect gravure printing, indirect screen printing, indirect electrophotography using liquid or dry toner, indirect spray varnishing methods, and combinations thereof.
[0024] In a preferred embodiment of the method using a printing press, the hardenable liquid medium is applied to an imaged or unimaged carrier. Accordingly, the carrier may also be a varnish plate (or dotting varnish plate) or an imaged printing plate.
[0025] In a preferred embodiment of the method using a printing press, a water-based UV varnish can also be used as a curable liquid medium, which is at least partially cured by heat in step iii) and finally cured by UV radiation after being transferred to the substrate.
[0026] It is also possible to sequentially manufacture multiple layers of different hardenable liquid media, each having different colorants enriched at the interface, in a printing press. Here, the printing press is preferably equipped with multiple printing units arranged sequentially, wherein the method of the present invention is implemented in each printing unit, preferably using different colorants enriched at the interface. In other printing units, other printing inks or varnishes known in principle, which do not have colorants enriched at the interface, can also be printed, as in the prior art.
[0027] In a particularly preferred embodiment, the invention also relates to a method for manufacturing a coating using a printing press, wherein the coating has at least one float pigment, the method comprising the following steps:
[0028] i) Provide curable printing inks or curable printing varnishes, which include at least one floating pigment;
[0029] ii) Apply the curable printing ink or curable printing varnish to the cylinder or plate of a printing press, wherein the floating pigment is enriched at the interface between the curable printing ink or curable printing varnish and the ambient atmosphere.
[0030] iii) To at least partially harden the hardenable printing ink or hardenable printing varnish on the cylinder or plate of the printing press; and
[0031] iv) Transferring at least partially hardened hardenable printing ink or hardenable printing varnish from the cylinder or plate of the printing press to the substrate, such that the floating pigment is concentrated on the side of the cylinder or plate of the printing press against the substrate.
[0032] In this particularly preferred embodiment, paper, cardboard, and plastic foil are preferred as printing materials. At least partial curing in step iii) is preferably carried out by means of electron radiation or UV radiation, particularly UV radiation. It may also involve only UV-based pinning, where the printed matter is then finally cured at a later point (before leaving the printing press) by irradiation with a higher dose of UV radiation. In this particularly preferred embodiment, the printing press cylinders or platen preferably have a release coating, such as a cylinder sleeve formed of an elastomer, by means of which facilitates the transfer of at least partially cured curable printing ink or curable printing varnish from the cylinders or platen to the printing material.
[0033] The subject matter of this invention also relates to the application of the method of this invention for manufacturing abrasion-resistant coatings comprising pigments. Here, in a preferred embodiment, it relates to mechanically sensitive pigments, preferably selected from the effect pigments already mentioned above and their preferred embodiments. In a preferred embodiment, the application of this invention relates to its use in printing presses, particularly offset printing presses, by a printing method.
[0034] The subject matter of this invention also relates to a printed matter obtained by the method of this invention. Preferably, it relates to a printed matter obtained by printing on all common substrates that can be processed in a printing press, and particularly preferably to a printed matter obtained by printing on paper, cardboard, or plastic foil. Despite the use of floating pigments, this printed matter has a visually appealing appearance while exhibiting high abrasion resistance. Attached Figure Description
[0035] Figure 1 The illustration schematically shows a printed matter with non-floating pigments in the prior art;
[0036] Figure 2 This illustration shows another printed matter with floating pigments in the prior art;
[0037] Figure 3 The method of the present invention is illustrated schematically;
[0038] Figure 4 The method of the present invention is illustrated schematically and in a strongly simplified manner. Detailed Implementation
[0039] Figure 1 The illustration schematically depicts a prior art printed material containing non-floating pigments. A curable liquid medium, such as varnish, containing non-floating pigment 3, is printed onto a substrate 1, such as cardboard, and dried, thereby hardening the curable medium and obtaining a usable printed material in which the non-floating pigment 3 is distributed within the hardened curable medium 2. Such printed materials generally have no problems in terms of mechanical stability, but when using metallic effect pigments as non-floating pigments, the visual metallic effect is often not particularly outstanding.
[0040] Figure 2 This illustration schematically shows another printed product with floating pigments in the prior art. A curable liquid medium, such as varnish, containing floating pigment 4, is printed onto a substrate 1, such as cardboard, and dried, thereby hardening the curable medium. The floating pigment 4 is pre-concentrated on the outer surface of the curable medium. A transparent protective layer 5, such as varnish, is applied to the hardened curable liquid medium 2 containing floating pigment 4 and then dried. This type of printed product typically exhibits a particularly excellent visual metallic effect when using metallic effect pigments as floating pigments, but it is relatively labor-intensive to manufacture.
[0041] Figure 3 The method of the present invention is illustrated schematically. In step S1, a carrier, such as a printing press cylinder, is provided. In step S2, the carrier 6 is coated with an uncured curable liquid medium 5 (containing floating pigment 4). This step can be performed, for example, through contact between the carrier, particularly the printing press cylinder, and another printing press cylinder, particularly a metering roller such as an anilox roller. In step S3, the floating pigment in the uncured liquid medium 7 floats and accumulates at the interface between the uncured curable liquid medium 7 and the surrounding atmosphere. In step S4, the uncured liquid medium 7 is cured, for example, by irradiation with UV radiation, thereby obtaining a cured curable liquid medium 2 on the carrier 6. In step S5, the cured curable liquid medium 2 is contacted with a substrate 1, such as cardboard or foil, such that the side of the carrier 6 rich in floating pigment 4 rests against the substrate 1. Step S6 illustrates a unit consisting of a carrier 6 having the cured curable liquid medium 2 and a substrate 1. In step S7, the carrier 6 is removed, leaving the unit consisting of the carrier 6 having the hardened curable liquid medium 2 and the substrate 1. This unit is shown in step S8. Here, the sensitive floating pigment 4 is protected away from the outer surface of the coated article.
[0042] Figure 4 The method of the present invention is illustrated schematically and in a strongly simplified manner. First, a hardened coating of a hardenable liquid medium 2 (containing floating pigment 4) is formed on a carrier 6. The floating pigment naturally accumulates at the interface between the liquid medium and the surrounding atmosphere and is fixed in that location by hardening. The carrier 6, thus coated, comes into contact with a substrate 1, such that the side enriched with floating pigment 4 adheres as closely as possible to the substrate 1. Next, the carrier 6 is removed. As a result, a coated article 8 is obtained, in which the sensitive floating pigment is contained internally in a protected manner away from the outer surface of the coated article 8.
[0043] Reference Marker Table
[0044] 1 Substrate
[0045] 2. Hardened hardenable liquid medium
[0046] 3. Non-floating pigments
[0047] 4. Floating pigments
[0048] 5. Transparent protective layer
[0049] 6. Carrier
[0050] 7 Uncured hardenable liquid media
[0051] 8. Coated products.
Claims
1. A method for manufacturing a coating having at least one colorant enriched at an interface, the method comprising the steps of: i) Provide a hardenable liquid medium comprising at least one colorant enriched at the interface; ii) Applying the curable liquid medium to a carrier, wherein the colorant enriched at the interface is enriched at the interface between the curable liquid medium and the surrounding ambient atmosphere; iii) Harden the hardenable liquid medium at least partially on the carrier; and iv) Transferring at least partially hardenable hardenable liquid medium from the carrier to the substrate, such that the side of the colorant enriched at the interface on the carrier adheres to the substrate.
2. The method according to claim 1, wherein, The at least one colorant enriched at the interface accumulates at the interface between the curable liquid medium and the surrounding atmosphere due to its lower density and / or surface properties compared to the curable liquid medium.
3. The method according to claim 1 or 2, wherein, The at least one colorant enriched at the interface is at least one effect pigment.
4. The method according to claim 1 or 2, wherein, The at least one colorant enriched at the interface is at least one inorganic metallic effect pigment.
5. The method according to claim 1 or 2, wherein, The at least one colorant enriched at the interface is at least one floating pigment.
6. The method according to claim 1 or 2, wherein, The hardenable liquid medium is substantially transparent.
7. The method according to claim 1 or 2, wherein, This method is implemented using a printing press.
8. The method according to claim 7, wherein, The carrier is the roller of a printing press.
9. The method according to claim 1 or 2, wherein, The curable liquid medium, which includes at least one colorant enriched at the interface, is a printing ink or printing varnish.
10. The method according to claim 1 or 2, wherein, The substrate is selected from paper, cardboard and plastic foil.
11. The method according to claim 1 or 2, comprising the following steps: i) Provide curable printing inks or curable printing varnishes, which include at least one floating pigment; ii) Applying the curable printing ink or curable printing varnish to the cylinder or plate of a printing press, wherein the floating pigment is enriched at the interface between the curable printing ink or curable printing varnish and the ambient atmosphere. iii) To at least partially harden the hardenable printing ink or hardenable printing varnish on the cylinder or plate of the printing press; and iv) Transferring at least partially hardened hardenable printing ink or hardenable printing varnish from the cylinder or plate of the printing press to the substrate, such that the side of the floating pigment concentrated on the cylinder or plate of the printing press adheres to the substrate.