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CA-3028552-C - MULTICOMPONENT REACTIVE INKS AND PRINTING METHOD

CA3028552CCA 3028552 CCA3028552 CCA 3028552CCA-3028552-C

Abstract

A printing system for printing a security feature in the form of a latent image comprising at least three compositions (RI), (C1) and (C2): (RI) a reactive ink comprising a silane compound (A) comprising at least a first and a second polymerizable moiety which are different from each other and are polymerizable by different mechanisms, loaded in a first reservoir of a first printhead, (C1) a first catalyst composition comprising a substance able to react with the silane compound (A) of composition (RI) and promote the polymerization of the first polymerizable moiety, loaded in a second reservoir of said first printhead or of a second printhead, (C2) a second catalyst composition comprising a substance able to react, alone or in presence of composition (C1), with the silane compound (A) of composition (RI) and promote the polymerization of the second polymerizable moiety.

Inventors

  • Davide Ciampini

Assignees

  • SICPA HOLDING SA

Dates

Publication Date
20260505
Application Date
20170725
Priority Date
20160725

Claims (20)

  1. CLAIMS 1. A printing system for printing a security feature comprising at least three compositions (RI), (C1) and (C2): (RI) a reactive ink comprising a silane compound (A) comprising at least a first polymerizable moiety and a second polymerizable moiety which are different from each other and are polymerizable by different mechanisms, loaded in a first reservoir of a first printhead, (C1) a first catalyst composition comprising a substance that reacts with the silane compound (A) of composition (RI) and promotes the polymerization of the first polymerizable moiety, loaded in a second reservoir of said first printhead or of a second printhead, (C2) a second catalyst composition comprising a substance that reacts, alone or in presence of composition (C1), with the silane compound (A) of composition (RI) and promotes the polymerization of the second polymerizable moiety, loaded in a third reservoir of said first printhead, or of said second printhead, or of a third printhead.
  2. 2. The printing system of claim 1, wherein at least one of the reactive ink (RI), the first catalyst composition (C1) and the second catalyst composition (C2) further comprises a dye or a pigment.
  3. 3. The printing system of claim 1 or claim 2, wherein one of the first and the second polymerizable moiety in the silane compound (A) is an epoxide group, an 55 alkoxysilane group, a (meth)acrylic group, a vinyl group or an amino group.
  4. 4. The printing system of claim 1 or claim 2, wherein the first polymerizable moiety is a group forming a polysiloxane, and wherein the second polymerizable moiety is selected from polymerizable moieties forming a polymer other than a polysiloxane.
  5. 5. The printing system of claim 4, wherein the first polymerizable moiety is selected from a tri C1 6alkoxysilane group and a trihalogensilane group, and wherein the second polymerizable moiety is selected from an epoxy group or other cyclic ether group, an ethylenically unsaturated group, a tetrasulfide group, an amino group, a carboxylic acid ester group, and a hydroxyl group.
  6. 6. The printing system of any one of claims 1-5, wherein the different polymerization mechanisms are different mechanisms selected from cationic, anionic, radical, and condensation polymerization.
  7. 7. The printing system of any one of claims 1-6, wherein the silane compound (A) is a compound of formula (i) or (ii): R13Si-L-S4-L-SiR13 (i) wherein L is C1-6-alkylene, and R1 each independently is C1-6-alkoxy or halogen; or RnSi(R1)m (ii) 56 wherein R1 each independently is C1-6-alkoxy or halogen, n = 1 or 2, (n+m) = 4, and R each independently is vinyl, phenyl, or C1-6-alkyl optionally substituted with one or more group(s) selected from epoxy, epoxy-(C1-6)-alkyloxy, C5-7-cycloalkyl having an epoxide functionality, cyano, halogen, amino, C1-6-alkylamino, di(C1-6-alkyl)amino, amino-C1-6-alkylamino, acryloyloxy, methacryloyloxy, and vinyl; with at least one R being vinyl, phenyl, or substituted C1-6-alkyl.
  8. 8. The printing system of claim 7 wherein the compound (A) is a compound of formula (ii), and wherein in formula (ii) R1 is C1-6-alkoxy and n = 1.
  9. 9. The printing system of claim 8 wherein all groups R1 are the same and are selected from methoxy, ethoxy and propoxy.
  10. 10. The printing system of claim 9 wherein the silane compound (A) is selected from (3 glycidyloxypropyl)trimethoxysilane (GPS), aminopropyltriethoxysilane (APTES), N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, trimethoxy[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]silane, and bis[3-(triethoxysilyl)propyl] tetrasulfide.
  11. 11. The printing system of any one of claims 1-10 wherein (RI) and/or (C2) further comprises (mercaptopropyl)trimethoxysilane (3-MPTS). 57
  12. 12. The printing system of any one of claims 1-11 wherein (C1) is a solution having a pH of ≥ 8.
  13. 13. The printing system of claim 12, wherein (C1) is a solution having a pH of ≥ 9.
  14. 14. The printing system of claim 12 wherein (C1) is a solution of an amine or of a hydroxide, a carbonate or a hydrogen carbonate of ammonium, tetramethylammonium or an alkaline or alkaline earth metal.
  15. 15. The printing system of any one of claims 1-14 wherein (C2) is a solution having a pH of ≤ 7.
  16. 16. The printing system of claim 15, wherein (C2) is a solution having a pH of ≤ 5.
  17. 17. The printing system of claim 15 wherein (C2) comprises an acid selected from hexafluoroantimonic acid (HSbF6), sulfuric acid (H2SO4), hydrochloric acid (HCl), triflic acid (CF3SO3H), and hexafluorophosphoric acid (HPF6).
  18. 18. The printing system of any one of claims 10-17 wherein at least one of (C1) and (C2) further comprises a mixture of water and ethanol as a solvent.
  19. 19. The printing system of any one of claims 1-18, wherein one or more of (RI), (C1) and (C2) further comprises a surfactant.
  20. 20. The printing system of claim 2 or any one of claims 3 to 19, when dependent upon claim 2, wherein the dye is 58 included in (RI) and is selected from Solvent Black 27; and/or Solvent Black 29.

Description

MULTICOMPONENT REACTIVE INKS AND PRINTING METHOD Field of the invention The invention relates to printing systems for printing security features. In particular the presented invention provides a new method to print an image with hidden patterns (latent images), suitable for use in security applications as e.g. a security feature. The invention also relates to a printed object obtained by the method. Background of the invention In the should following we will be understood description. define certain according to terms the as they present The term "security feature" describes an element that can be used for authentication purposes. Such a security feature can be in any form, i.e. an image or a graphic element. It may comprise a serial number, a printed text, a printed pattern, a designs or code made of a security ink, an intaglio printed pattern or design, a security thread or stripe, a window, fibers, planchettes, a foil, a decal, an hologram, microprintings, a 3-D security ribbon, and/ or watermarks. Further the security feature as described herein may comprise a pattern representing a code selected from the group comprising special characters, series of alphanumerical characters and combinations thereof. Alternatively, the security feature may comprise a 1-dimensional barcode, a stacked 1- dimensional barcode, a 2-dimensional barcode (such as a 1 Date Rec;ue/Date Received 2024-02-05 DataMatrix or a QR-Code) and/or a 3-dimensional barcode. Such a code may comprise additional or redundant information in an encoded form so that it is generally not readable or understandable without a key or a procedure to decode the encoded information. The security feature may further be invisible to the naked eye. An "image" according to this description can be an image that is immediately detectable with the naked eye, or can be a latent image, as defined below. comprise one or more areas that An "image" can also is/are immediately detectable by the naked eye, and/or one or more areas forming a latent image. A printed object comprises an image as defined above, and in one embodiment of the present invention the printed object is in the form of a security feature. "Latent images" according to this description may comprise images comprising hidden patterns, which are not immediately detectable with the naked eye, but become detectable after a suitable physical, mechanical or chemical treatment or illumination. Latent images may be used in security applications as a security feature. Examples are pressure-sensitive or hot stamped labels with a normal (gray or colored) appearance. When viewed via a special filter (such as a polarizer) an additional, normally latent, image appears. Also so called bleeding inks can provide latent images, which appear or disappear only after specific physical, mechanical or chemical conditions are applied to said inks/images. In the field of printing it is advantageous if the printed pattern shows good adhesion and mechanical properties on different surfaces, in particular on non- 2 Date Rec;ue/Date Received 2024-02-05 porous surfaces like glass, metals, plastics etc .. Furthermore, in certain applications it can be important that the printed codes are not easy to be reproduced or counterfeited. In order to obtain good adhesion and resistance of the printed image/pattern, the following two approaches are usually employed: • Ink sol vent swelling of the medium, i.e. a process wherein the dye inside the ink penetrates the substrate • Reticulation (cross-linking/fixation) of the ink induced by radiation, i.e. using an ink that contains reactive components (monomers, photoinitiators, etc.). "Reticulation" in general describes a polymerization, whereby monomers once reacted generate a crosslinked polymeric matrix. Methods involving reticulation are employed, for example, in the processes described in the following documents. US 7,608,388 B2 relates to lithographic printing members image able using a combination of inkjet and photopolymerization. The lithographic printing members are said to comprise a photosensitive top layer containing a photo-polymerizable moiety and the first component of a two-component photo-polymerization initiating system. This top layer contains acrylates having one or more reactive acrylic moiety which undergo photopolymerization and become crosslinked when reacted with an imaging fluid containing the second component of the two-component photo-polymerization initiating system and subjected to actinic radiation. Removal of the nonimage portions of the top layer with a solvent allows a printing member with an imagewise lithographic pattern on it to be obtained. 3 Date Rec;ue/Date Received 2024-02-05 US 7,632,423 B2 describes reactive fine particles comprising one or more functional compounds such as latent curing agents. It also describes a liquid thermosetting compound comprising the reactive fine particles and adapted to be cured thereby, e.g. through initiation of cross li