WO2001007175A1

WO2001007175A1 - Metallic printing procedures

Info

Publication number: WO2001007175A1
Application number: PCT/NZ2000/000137
Authority: WO
Inventors: Joseph Vincent Nealis
Original assignee: Carter Holt Harvey Limited
Priority date: 1999-07-28
Filing date: 2000-07-26
Publication date: 2001-02-01
Also published as: AR024980A1; AU6325900A; NZ336974A

Abstract

A method of providing a better metallic appearance from a printing with a metallic ink which involves the provision thereunder (whether directly or indirectly thereunder) a layer (2) of an at least in part UV cured liquid composition. Optional other coatings can be interposed and/or over applied.

Description

"METALLIC PRINTING PROCEDURES"

The present invention relates to a metallic printing procedure and to related products and methods. Unless a substrate such as, by way of example, a paperboard is to be printed by a gravure process it is difficult to print a high quality metallic lustre. Even with the gravure process the appearance of any metallic printing is not to a standard that is always acceptable. Frequently for example, gold printing appears bronze in character. In such circumstances therefore recourse is sometimes taken to the use of gold leaf to provide the enhanced gold appearance that might be required. The use however of gold leaf is expensive and makes normal printing procedures inappropriate. Such an alternative may not be available for other metallic inks.

The use of an in line printing process whereby a metallic appearance at least as good as that of a gravure process (if not better) is obtained has been a long felt want. The prospect of lithographic type printing with, for example, gold ink to an acceptable standard is much needed.

We have determined that prior art printing process using metallic inks have involved, for example, where a paperboard substrate is being used, the provision of a first printed metallic ink layer and then an overprinting on that base metallic ink printed layer of a further metallic ink layer. Where such serial metallic ink printings take place the ove rinting still provides an unsatisfactory metallic appearance, ie; if gold is often bronze or dull in appearance.

We have discovered a surprising consequence of using an alternative to the base layer of the metallic ink itself which, with care, provides a far better metallic appearance outcome.

The term "print", "printing" or "printed" as used herein to is not restricted as to the nature of the display to be provided, ie; it can assume the form of a general or regional coating or it can be confined to logos, alpha numerics or the like. Moreover the mode of the provision of any such "print" can involve any recognised method of printing or coating including pressure transfer, ink jet or the equivalent spray application, etc. provided however, in each instance, the delivery is of a liquid or liquid carried composition (ie; hereafter included in the term "liquid composition") rather than as a powder or a non liquid film or foil.

In a first aspect the invention consists in a method of providing a metallic appearance on a substrate, said method comprising or including providing or ensuring said substrate includes on a surface thereof a base of an at least in part UV cured liquid composition following its printing thereon, optionally applying an aqueous coating seal over the surface of said base, and applying a liquid composition of a metallic character over the base (and any optional cured aqueous coating seal thereon) which upon set or drying provides said metallic appearance.

Preferably said liquid composition of a metallic character is a metallic ink.

Preferably said metallic ink is an aqueous metallic ink.

Preferably said liquid composition of a metallic character is applied by a printing procedure as hereinbefore defined. Preferably said base is applied by a printing procedure as hereinbefore defined.

Preferably said liquid composition of a metallic character is cured by heat.

Preferably said base of an at least in part UV cured liquid composition is a base provided by applying a UV curable ink and thereafter curing the ink with UV radiation.

In one form preferably no aqueous coating seal is interposed between said base and said liquid composition of a metallic character.

In another form preferably an aqueous coating seal is interposed between said base and said liquid composition of a metallic character.

Preferably said aqueous coating seal is cured with heat.

Preferably said aqueous coating seal is applied by a printing procedure as hereinbefore defined.

Preferably said substrate is a paper or the like fibrous substrate.

In another aspect the invention is a method as aforesaid when performed substantially as herein described with reference to any one of Figures 4 to 8 of the accompanying drawings. In still another aspect the invention is a method of providing a metallic appearance on a paper or other fibrous substrate substantially as hereinbefore described with reference to any of Figures 4 to 8 hereof.

In yet another aspect the invention is a product provided with a metallic appearance on at least part thereof by a method of the present invention.

In another aspect the invention is metallic appearance type coatings or printing substantially of a kind as herein described with reference to Figure 2 and 3 of the accompanying drawings.

In another aspect the invention is a product of any of the kinds aforesaid which when tested on a gloss meter at 60° (substantially as herein described with reference to the examples) has a reading greater than 60. To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting. Preferred forms of the present invention will now be described with reference to the accompanying drawings in which;

Figure 1 shows a cross-section on a paperboard or other substrate having a metallic ink upon metallic ink overlaid printing such as is conventionally used yet which provides a less than brilliant metallic appearance, Figure 2 is a similar view to that of Figure 1 but showing the three layer printing preferably used in accordance with the present invention where the initial printing of the substrate (whether paperboard or otherwise) is with a UV ink,

Figure 3 shows an alternative to the sequence of Figure 2 where, whilst the base on the substrate is again a printing of a UV ink, no sealant layer is provided thereover but rather is used over top of a gold coating overprinting of the cured UV ink,

Figure 4 shows an alternative to the sequence of Figure 3, whilst the base on the substrate is again a printing of a UV ink, no sealing layer is provided, rather a gold coating over printing and again a gold coating over printing,

Figures 5, 6 and Figure 7 are as in Figures 2, 3, and 4 with the aqueous coating or seal being substituted by a UV coating, and

Figure 8 shows yet another print sequence. LAYER SYMBOL EXPLANATION:

1. P = Printed Conventional

2. PU = Printed U.V.

3. AMC = Aqueous Metallic Coating 4. AQC = Aqueous Coating or Seal

5. CUVM = Coating U.V. Metallic

6. CUV = Coating U.V.

7. S = Substrate

Figure 1 PPPPPPPPPPPPPPPP

PPPPPPPPPPPPPPPP

SSSSSSSSSSSSSSSS

Figure 2 AMCAMCAMCAMC AQCAQCAQCAQCA

PUPUPUPUPUPUPUP SSSSSSSSSSSSSSSSS

Figure 3 AQCAQCAQCAQCA AMCAMCAMCAMC

PUPUPUPUPUPUPUP SSSSSSSSSSSSSSSSS

Figure 4 AMCAMCAMCAMC AMCAMCAMCAMC

PUPUPUPUPUPUPUP SSSSSSSSSSSSSSSSS Figure 5 CUVMCUVMCUVM cuvcuvcuvcuvc

PUPUPUPUPUPUPUP SSSSSSSSSSSSSSSSS

Figure 6 CUVMCUVMCUVM CUVCUVCUVCUVC PUPUPUPUPUPUPUP SSSSSSSSSSSSSSSSS

Figure 7 CUVCUVCUVCUVC CUVMCUVMCUVM PUPUPUPUPUPUPUP SSSSSSSSSSSSSSSSS

Figure 8 CUVMCUVMCUVM CUVMCUVMCUVM CUVCUVCUVCUVC

SSSSSSSSSSSSSSSS

EXPLANATION OF CURE SEQUENCE:

Figure 1: Example of Normal Gold Procedure

Figure 2: UV LNK/UV CURED//AQU COAT/IR CURED//AQU MET COAT/IR

CURED Figure 3: UV LNK/UV CURED//AQU MET COAT/IR CURED//AQU COAT/IR

CURED Figure 4 : UV INK/UV CURED//AQU MET COAT/TR CURED//AQU MET COAT/LR

CURED Figure 5: UV LNK/UV CURED//UV COAT/UV CURED//UV MET COAT/UV CURED Figure 6: UV LNK/UV CURED//UV MET COAT/UV CURED//UV COAT/UV CURED

Figure 7: UV LNK/UV CURED//UVMET COAT/UV CURED//UV COAT/UV CURED Figure 8: UV LNK UV CURED//UV MET COAT/UV CURED/UV MET COAT/UV CURED.

As used herein the terminology UV ink involves an ink capable of being cured with ultraviolet light. The UV ink can be of any required colour to achieve the end result.

The cure of the UV ink base arises by the reaction of monomers and acrylated resins with photo-initiators which act as catalysts in the presence of the curing UV light.

A suitable metallic ink (eg; gold or silver inks where the metal content is bronze/brass or aluminium respectively) that of ECKART- WERKE marketed under the trade mark and branding ROTOSTAR™. Other possible metallic inks to be used are those of SICPA (AQUATECH™) or HUBER GRUPPE (ACRYLAC™)

The level of UV light required for the curing is determined by the nature of the ink used. The term "aqueous coating printing/coating" is of an aqueous coating seal is similar to the carrier of the aforementioned metallic inks, ie; an acrylic emulsion modified with acrylic solution resins. The curing therefore is preferably with infra-red radiation (or with a light having an IR component) which cures by evaporation of water and the co-solvent followed by coalescence of the emulsion particles. The composition is that of an acrylic emulsion modified with acrylic solution resins in the aqueous/co- solvent system.

The metallic ink printing if to provide a gold lustre is preferably with an aqueous based gold ink typified by the ROTOSTAR™ product. The curing therefore is preferably with infra-red radiation or light having an IR component. The systems of the present invention depart from the prior art in that a UV ink is applied by printing (eg; lithographic printing) first as a base and subsequent thereto there is then the provision (directly or after the use of an aqueous seal) of the aqueous metallic ink. Each such application is preferably by printing or coating.

In some forms of the present invention of course the aqueous coating printing in the procedure of Figure 2 to 4 need not be coextensive only with the base of UV ink. Likewise for the procedure of Figure 5 to 7. The metallic ink printing of each of the procedures of Figure 2 to 4 and 5 to 7 need not be simply co-extensive with the UV ink printing and/or any underlying (if any) aqueous coating print.

Persons skilled in the art will appreciate the alternatives available. The arrangement of Figure 2, 4, 6 and 8 results in the prospect of a surprisingly high metallic (eg; gold-like) finish. The procedure of Figures 3, 5 and 7 produces a harder though less brilliant finish. Nevertheless, the Figures 3, 5 and 7 procedure produces an acceptable metallic (eg; gold-like) finish.

The processes can be either all in line or individual printing cures. In Figures 1 to 7 the reference numerals represent the following: i) Substrate ii) Metallic Ink Print iii) UV Ink Print iv) Aqueous Sealing Print.

Comparative gloss readings were then made using a BYK/CHEMIE gloss meter at 60 degrees (DIN 67530, ISO 2813, ASTM D523). These comparative trials were with arrangements as depicted in Figures 1 through 3.

Example 1:

In Figure 1 the substrate 1 was Springhill High Yield Bristol board and each of the metallic ink layers 2 were conventional U.V. ink.

Example 2: With the arrangement of Figure 2 the substrate 1 was Springhill High Yield Bristol board, layer 3 is aqueous metallic ink print, layer 4 is aqueous metallic ink print and layer 2 is U.V. base ink print.

Example 3: With the arrangement of Figure 3 the substrate 1 is Springhill High Yield Bristol board, layer 3 is metallic ink print, layer 2 is U.V. ink print and layer 4 is aqueous print. The comparative gloss meter readings were as follows;

Results:

• Example 1 - 52 • Example 2 - 97

• Example 3 - 75

An alternative arrangement of Figures 6 to 8 which uses UV material (namely, Eckart-Werke) gives a similar reading to that obtained for aqueous at 2 to 5.

Claims

CLAIMS:

1. A method of providing a metallic appearance on a substrate, said method comprising or including providing or ensuring said substrate includes on a surface thereof a base of an at least in part UV cured liquid composition following its printing thereon, optionally applying an aqueous coating seal over the surface of said base, and applying a liquid composition of a metallic character over the base (and any optional cured aqueous coating seal thereon) which upon set or drying provides said metallic appearance.

2. A method of claim 1 wherein said liquid composition of a metallic character is a metallic ink.

3. A method as claimed in claim 2 wherein said metallic ink is an aqueous metallic ink.

4. A method of any one of the preceding claims wherein said liquid composition of a metallic character is applied by a printing procedure as hereinbefore defined.

5. A method of any one of the preceding claims wherein said base is applied by a printing procedure as hereinbefore defined.

6 A method as claimed in any one of the preceding claims wherein said liquid composition of a metallic character is cured by heat.

7. A method as claimed in any one of the preceding claims wherein said base of an at least in part UV cured liquid composition is a base provided by applying a UV curable ink and thereafter curing the ink with UV radiation.

8. A method as claimed in any one of the preceding claims wherein no aqueous coating seal is interposed between said base and said liquid composition of a metallic character.

9. A method as claimed in any one of claims 1 to 7 wherein an aqueous coating seal is interposed between said base and said liquid composition of a metallic character.

10. A method as claimed in claim 7 wherein said aqueous coating seal is cured with heat.

11. A method of claim 9 or 10 wherein said aqueous coating seal is applied by a printing procedure as hereinbefore defined.

12. A method of any one of the preceding claims wherein said substrate is a paper or the like fibrous substrate.

13. A method as claimed in any one of the preceding claims when performed substantially as hereinbefore described with reference to any one of Figures 4 to 7 of the accompanying drawings.

14. A method of providing a metallic appearance on a paper or other fibrous substrate substantially as hereinbefore described with reference to any of Figures 4 to 7 hereof.

15. A product provided with a metallic appearance on at least part thereof by a method as claimed in any one of the preceding claims.

16. Metallic appearance type coatings or printing substantially of a kind as hereinbefore described with reference to Figure 2 and 3 of the accompanying drawings.

17. A product having a metallic appearance of a king as claimed in claim 16 or as is provided by a method of any one of claims 1 to 14 where, when tested on a gloss meter at 60 ° substantially as herein described with reference to the examples has a reading greater than 60.