OA19872A - Processes for producing optical effects layers. - Google Patents
Processes for producing optical effects layers. Download PDFInfo
- Publication number
- OA19872A OA19872A OA1202000246 OA19872A OA 19872 A OA19872 A OA 19872A OA 1202000246 OA1202000246 OA 1202000246 OA 19872 A OA19872 A OA 19872A
- Authority
- OA
- OAPI
- Prior art keywords
- magnetic
- pigment particles
- substrate
- platelet
- generating device
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims abstract description 72
- 230000003287 optical Effects 0.000 title claims abstract description 67
- 230000005291 magnetic Effects 0.000 claims abstract description 377
- 239000002245 particle Substances 0.000 claims abstract description 180
- 239000000049 pigment Substances 0.000 claims abstract description 171
- 239000000758 substrate Substances 0.000 claims abstract description 138
- 238000007639 printing Methods 0.000 claims abstract description 70
- 230000003068 static Effects 0.000 claims abstract description 31
- 239000010410 layer Substances 0.000 claims description 105
- 239000011247 coating layer Substances 0.000 claims description 101
- 239000008199 coating composition Substances 0.000 claims description 84
- 239000000203 mixture Substances 0.000 claims description 49
- 239000000463 material Substances 0.000 claims description 40
- 229920003023 plastic Polymers 0.000 claims description 14
- 239000004033 plastic Substances 0.000 claims description 14
- 238000007650 screen-printing Methods 0.000 claims description 14
- 230000036962 time dependent Effects 0.000 claims description 13
- 229920000642 polymer Polymers 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 10
- 229910052751 metal Inorganic materials 0.000 claims description 10
- 239000002184 metal Substances 0.000 claims description 10
- 150000002739 metals Chemical class 0.000 claims description 10
- 239000010409 thin film Substances 0.000 claims description 9
- 239000000696 magnetic material Substances 0.000 claims description 7
- 239000004986 Cholesteric liquid crystals (ChLC) Substances 0.000 claims description 6
- 238000007647 flexography Methods 0.000 claims description 6
- 239000002657 fibrous material Substances 0.000 claims description 4
- 239000002131 composite material Substances 0.000 claims description 3
- 239000011521 glass Substances 0.000 claims description 3
- 239000000919 ceramic Substances 0.000 claims description 2
- 231100000616 occupational exposure limit Toxicity 0.000 abstract 1
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 47
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 35
- 239000000976 ink Substances 0.000 description 27
- 239000011230 binding agent Substances 0.000 description 23
- 239000011651 chromium Substances 0.000 description 19
- 229910052782 aluminium Inorganic materials 0.000 description 17
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminum Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 17
- 230000000694 effects Effects 0.000 description 17
- 229910052759 nickel Inorganic materials 0.000 description 17
- -1 hématite (Fe2O3) Chemical class 0.000 description 16
- 239000011248 coating agent Substances 0.000 description 15
- 238000000576 coating method Methods 0.000 description 15
- 150000001875 compounds Chemical class 0.000 description 14
- 229910052742 iron Inorganic materials 0.000 description 14
- 229910045601 alloy Inorganic materials 0.000 description 12
- 239000000956 alloy Substances 0.000 description 12
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 12
- 229910052803 cobalt Inorganic materials 0.000 description 12
- 239000010941 cobalt Substances 0.000 description 12
- 239000006096 absorbing agent Substances 0.000 description 11
- 239000000126 substance Substances 0.000 description 11
- 229910052804 chromium Inorganic materials 0.000 description 10
- VYZAMTAEIAYCRO-UHFFFAOYSA-N chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 9
- 229920002866 paraformaldehyde Polymers 0.000 description 9
- 239000003211 photoinitiator Substances 0.000 description 9
- 238000003847 radiation curing Methods 0.000 description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 9
- 238000006243 chemical reaction Methods 0.000 description 8
- 239000010949 copper Substances 0.000 description 8
- 239000000654 additive Substances 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 239000004696 Poly ether ether ketone Substances 0.000 description 6
- 239000000853 adhesive Substances 0.000 description 6
- 230000001070 adhesive Effects 0.000 description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N al2o3 Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 6
- 239000003054 catalyst Substances 0.000 description 6
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 6
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 6
- 229920002530 poly[4-(4-benzoylphenoxy)phenol] polymer Polymers 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- 239000002904 solvent Substances 0.000 description 6
- 239000010936 titanium Substances 0.000 description 6
- 239000004952 Polyamide Substances 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 5
- RYGMFSIKBFXOCR-UHFFFAOYSA-N copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 5
- 229910052802 copper Inorganic materials 0.000 description 5
- 230000005670 electromagnetic radiation Effects 0.000 description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-M fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 5
- 239000011888 foil Substances 0.000 description 5
- 238000005755 formation reaction Methods 0.000 description 5
- 229910001004 magnetic alloy Inorganic materials 0.000 description 5
- 229920002647 polyamide Polymers 0.000 description 5
- AYTAKQFHWFYBMA-UHFFFAOYSA-N Chromium(IV) oxide Chemical compound O=[Cr]=O AYTAKQFHWFYBMA-UHFFFAOYSA-N 0.000 description 4
- SZVJSHCCFOBDDC-UHFFFAOYSA-N Iron(II,III) oxide Chemical compound O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 4
- JEIPFZHSYJVQDO-UHFFFAOYSA-N Iron(III) oxide Chemical compound O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 4
- PQXKHYXIUOZZFA-UHFFFAOYSA-M Lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 description 4
- 239000004734 Polyphenylene sulfide Substances 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 4
- 238000007792 addition Methods 0.000 description 4
- 238000007774 anilox coating Methods 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 4
- 230000003098 cholesteric Effects 0.000 description 4
- 230000000875 corresponding Effects 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 239000010931 gold Substances 0.000 description 4
- 230000001965 increased Effects 0.000 description 4
- PWHULOQIROXLJO-UHFFFAOYSA-N manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 238000006011 modification reaction Methods 0.000 description 4
- 239000010955 niobium Substances 0.000 description 4
- 229920000069 poly(p-phenylene sulfide) Polymers 0.000 description 4
- 229920000728 polyester Polymers 0.000 description 4
- 238000006116 polymerization reaction Methods 0.000 description 4
- 239000011241 protective layer Substances 0.000 description 4
- 238000002310 reflectometry Methods 0.000 description 4
- 239000010948 rhodium Substances 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- 239000011780 sodium chloride Substances 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 4
- RTAQQCXQSZGOHL-UHFFFAOYSA-N titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 4
- 229910052719 titanium Inorganic materials 0.000 description 4
- 229910001929 titanium oxide Inorganic materials 0.000 description 4
- 229920000742 Cotton Polymers 0.000 description 3
- OGIDPMRJRNCKJF-UHFFFAOYSA-N TiO Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 3
- 125000002091 cationic group Chemical group 0.000 description 3
- 230000000295 complement Effects 0.000 description 3
- 239000004020 conductor Substances 0.000 description 3
- 239000002537 cosmetic Substances 0.000 description 3
- 238000004132 cross linking Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000000945 filler Substances 0.000 description 3
- 239000004700 high-density polyethylene Substances 0.000 description 3
- 230000001976 improved Effects 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 229910001172 neodymium magnet Inorganic materials 0.000 description 3
- 239000002861 polymer material Substances 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- BQCADISMDOOEFD-UHFFFAOYSA-N silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 3
- 229910052709 silver Inorganic materials 0.000 description 3
- 239000004332 silver Substances 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- 238000000870 ultraviolet spectroscopy Methods 0.000 description 3
- YIKSHDNOAYSSPX-UHFFFAOYSA-N 1-propan-2-ylthioxanthen-9-one Chemical compound S1C2=CC=CC=C2C(=O)C2=C1C=CC=C2C(C)C YIKSHDNOAYSSPX-UHFFFAOYSA-N 0.000 description 2
- BTJPUDCSZVCXFQ-UHFFFAOYSA-N 2,4-diethylthioxanthen-9-one Chemical compound C1=CC=C2C(=O)C3=CC(CC)=CC(CC)=C3SC2=C1 BTJPUDCSZVCXFQ-UHFFFAOYSA-N 0.000 description 2
- ZCDADJXRUCOCJE-UHFFFAOYSA-N 2-chlorothioxanthen-9-one Chemical compound C1=CC=C2C(=O)C3=CC(Cl)=CC=C3SC2=C1 ZCDADJXRUCOCJE-UHFFFAOYSA-N 0.000 description 2
- 241000242759 Actiniaria Species 0.000 description 2
- KLZUFWVZNOTSEM-UHFFFAOYSA-K AlF3 Chemical compound F[Al](F)F KLZUFWVZNOTSEM-UHFFFAOYSA-K 0.000 description 2
- OYLGJCQECKOTOL-UHFFFAOYSA-L Barium fluoride Chemical compound [F-].[F-].[Ba+2] OYLGJCQECKOTOL-UHFFFAOYSA-L 0.000 description 2
- WUKWITHWXAAZEY-UHFFFAOYSA-L Calcium fluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 2
- 210000004905 Finger nails Anatomy 0.000 description 2
- 229920002456 HOTAIR Polymers 0.000 description 2
- 210000000282 Nails Anatomy 0.000 description 2
- 229920000539 Poly[1,4-benzenedicarbonyl-alt-bis(4-phenoxyphenyl)methanone] Polymers 0.000 description 2
- 239000004698 Polyethylene (PE) Substances 0.000 description 2
- 229920001721 Polyimide Polymers 0.000 description 2
- 239000004642 Polyimide Substances 0.000 description 2
- 229920001131 Pulp (paper) Polymers 0.000 description 2
- 230000004913 activation Effects 0.000 description 2
- 239000002518 antifoaming agent Substances 0.000 description 2
- 230000000712 assembly Effects 0.000 description 2
- 229910001632 barium fluoride Inorganic materials 0.000 description 2
- 229910001634 calcium fluoride Inorganic materials 0.000 description 2
- 229940090961 chromium dioxide Drugs 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000002708 enhancing Effects 0.000 description 2
- 230000001747 exhibiting Effects 0.000 description 2
- 239000004744 fabric Substances 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 238000005187 foaming Methods 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000003112 inhibitor Substances 0.000 description 2
- 230000002401 inhibitory effect Effects 0.000 description 2
- 239000011229 interlayer Substances 0.000 description 2
- 230000001050 lubricating Effects 0.000 description 2
- 239000003550 marker Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000000178 monomer Substances 0.000 description 2
- 239000002086 nanomaterial Substances 0.000 description 2
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 2
- 229910052758 niobium Inorganic materials 0.000 description 2
- 239000005022 packaging material Substances 0.000 description 2
- 238000004806 packaging method and process Methods 0.000 description 2
- 229910052763 palladium Inorganic materials 0.000 description 2
- 239000003504 photosensitizing agent Substances 0.000 description 2
- 239000004014 plasticizer Substances 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 229920000515 polycarbonate Polymers 0.000 description 2
- 239000004417 polycarbonate Substances 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 229920000139 polyethylene terephthalate Polymers 0.000 description 2
- 239000005020 polyethylene terephthalate Substances 0.000 description 2
- 229920000098 polyolefin Polymers 0.000 description 2
- 229920001155 polypropylene Polymers 0.000 description 2
- 229920000915 polyvinyl chloride Polymers 0.000 description 2
- 230000002633 protecting Effects 0.000 description 2
- 230000001681 protective Effects 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 2
- 229910052703 rhodium Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000004094 surface-active agent Substances 0.000 description 2
- 229920001169 thermoplastic Polymers 0.000 description 2
- 229920005992 thermoplastic resin Polymers 0.000 description 2
- 229920001187 thermosetting polymer Polymers 0.000 description 2
- 229910052718 tin Inorganic materials 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N tin hydride Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 2
- 230000001131 transforming Effects 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium(0) Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 2
- 239000002966 varnish Substances 0.000 description 2
- 239000001993 wax Substances 0.000 description 2
- 239000002023 wood Substances 0.000 description 2
- ZDQNWDNMNKSMHI-UHFFFAOYSA-N 1-[2-(2-prop-2-enoyloxypropoxy)propoxy]propan-2-yl prop-2-enoate Chemical compound C=CC(=O)OC(C)COC(C)COCC(C)OC(=O)C=C ZDQNWDNMNKSMHI-UHFFFAOYSA-N 0.000 description 1
- KWOLFJPFCHCOCG-UHFFFAOYSA-N Acetophenone Natural products CC(=O)C1=CC=CC=C1 KWOLFJPFCHCOCG-UHFFFAOYSA-N 0.000 description 1
- 229910002016 Aerosil® 200 Inorganic materials 0.000 description 1
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 239000005995 Aluminium silicate Substances 0.000 description 1
- PZZYQPZGQPZBDN-UHFFFAOYSA-N Aluminium silicate Chemical compound O=[Al]O[Si](=O)O[Al]=O PZZYQPZGQPZBDN-UHFFFAOYSA-N 0.000 description 1
- 229910000531 Co alloy Inorganic materials 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- 101700083613 GLYR1 Proteins 0.000 description 1
- 229920000106 Liquid crystal polymer Polymers 0.000 description 1
- 239000004977 Liquid-crystal polymers (LCPs) Substances 0.000 description 1
- 229920001730 Moisture cure polyurethane Polymers 0.000 description 1
- 240000000907 Musa textilis Species 0.000 description 1
- LXCIHXPVYQKJAG-UHFFFAOYSA-N N-[aziridin-1-yl-(2-methylaziridin-1-yl)phosphoryl]-N-prop-2-enylprop-2-en-1-amine Chemical compound CC1CN1P(=O)(N(CC=C)CC=C)N1CC1 LXCIHXPVYQKJAG-UHFFFAOYSA-N 0.000 description 1
- 229910000990 Ni alloy Inorganic materials 0.000 description 1
- 240000008962 Nicotiana tabacum Species 0.000 description 1
- 235000002637 Nicotiana tabacum Nutrition 0.000 description 1
- 239000006057 Non-nutritive feed additive Substances 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 229920002544 Olefin fiber Polymers 0.000 description 1
- 229920000265 Polyparaphenylene Polymers 0.000 description 1
- 239000004721 Polyphenylene oxide Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 101710026165 SNRPF Proteins 0.000 description 1
- OJIKOZJGHCVMDC-UHFFFAOYSA-K Samarium(III) fluoride Chemical compound F[Sm](F)F OJIKOZJGHCVMDC-UHFFFAOYSA-K 0.000 description 1
- DAKWPKUUDNSNPN-UHFFFAOYSA-N TMPTA Chemical compound C=CC(=O)OCC(CC)(COC(=O)C=C)COC(=O)C=C DAKWPKUUDNSNPN-UHFFFAOYSA-N 0.000 description 1
- 229910001069 Ti alloy Inorganic materials 0.000 description 1
- 239000004775 Tyvek Substances 0.000 description 1
- 229920000690 Tyvek Polymers 0.000 description 1
- 239000004699 Ultra-high molecular weight polyethylene (UHMWPE) Substances 0.000 description 1
- 239000011358 absorbing material Substances 0.000 description 1
- 150000008062 acetophenones Chemical class 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 239000004676 acrylonitrile butadiene styrene Substances 0.000 description 1
- 230000000996 additive Effects 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 235000012211 aluminium silicate Nutrition 0.000 description 1
- 150000008366 benzophenones Chemical class 0.000 description 1
- 235000013361 beverage Nutrition 0.000 description 1
- 239000011127 biaxially oriented polypropylene Substances 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 description 1
- 229910052797 bismuth Inorganic materials 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 238000010382 chemical cross-linking Methods 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 238000004040 coloring Methods 0.000 description 1
- 239000006103 coloring component Substances 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000001419 dependent Effects 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drugs Drugs 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 238000010891 electric arc Methods 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- 238000001227 electron beam curing Methods 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 230000005293 ferrimagnetic Effects 0.000 description 1
- 230000005294 ferromagnetic Effects 0.000 description 1
- 150000002222 fluorine compounds Chemical class 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 239000003999 initiator Substances 0.000 description 1
- 230000000977 initiatory Effects 0.000 description 1
- 238000007641 inkjet printing Methods 0.000 description 1
- 239000001023 inorganic pigment Substances 0.000 description 1
- MGFYSGNNHQQTJW-UHFFFAOYSA-N iodonium Chemical class [IH2+] MGFYSGNNHQQTJW-UHFFFAOYSA-N 0.000 description 1
- 229910000460 iron oxide Inorganic materials 0.000 description 1
- 235000013980 iron oxide Nutrition 0.000 description 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000010902 jet-milling Methods 0.000 description 1
- 239000004922 lacquer Substances 0.000 description 1
- 230000004301 light adaptation Effects 0.000 description 1
- 231100000897 loss of orientation Toxicity 0.000 description 1
- 229910000529 magnetic ferrite Inorganic materials 0.000 description 1
- 239000002122 magnetic nanoparticle Substances 0.000 description 1
- 230000005415 magnetization Effects 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 238000001465 metallisation Methods 0.000 description 1
- 229910052618 mica group Inorganic materials 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 239000002417 nutraceutical Substances 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 239000004767 olefin fiber Substances 0.000 description 1
- 230000001590 oxidative Effects 0.000 description 1
- MPQXHAGKBWFSNV-UHFFFAOYSA-N oxidophosphanium Chemical class [PH3]=O MPQXHAGKBWFSNV-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-O oxonium Chemical compound [OH3+] XLYOFNOQVPJJNP-UHFFFAOYSA-O 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N oxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- SOQBVABWOPYFQZ-UHFFFAOYSA-N oxygen(2-);titanium(4+) Chemical class [O-2].[O-2].[Ti+4] SOQBVABWOPYFQZ-UHFFFAOYSA-N 0.000 description 1
- 230000036961 partial Effects 0.000 description 1
- 235000011837 pasties Nutrition 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000011528 polyamide (building material) Substances 0.000 description 1
- 229920001230 polyarylate Polymers 0.000 description 1
- 229920001707 polybutylene terephthalate Polymers 0.000 description 1
- 229920000570 polyether Polymers 0.000 description 1
- 229920001601 polyetherimide Polymers 0.000 description 1
- 229920005594 polymer fiber Polymers 0.000 description 1
- 230000000379 polymerizing Effects 0.000 description 1
- 229920001955 polyphenylene ether Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000003014 reinforcing Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 231100000489 sensitizer Toxicity 0.000 description 1
- 230000015541 sensory perception of touch Effects 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- 238000004513 sizing Methods 0.000 description 1
- 239000011343 solid material Substances 0.000 description 1
- 230000003595 spectral Effects 0.000 description 1
- 229910052566 spinel group Inorganic materials 0.000 description 1
- 238000009987 spinning Methods 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- PPBRXRYQALVLMV-UHFFFAOYSA-N styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 1
- RWSOTUBLDIXVET-UHFFFAOYSA-O sulfonium Chemical class [SH3+] RWSOTUBLDIXVET-UHFFFAOYSA-O 0.000 description 1
- 230000001360 synchronised Effects 0.000 description 1
- 229920002994 synthetic fiber Polymers 0.000 description 1
- 239000012209 synthetic fiber Substances 0.000 description 1
- 239000000454 talc Substances 0.000 description 1
- 229910052623 talc Inorganic materials 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
- YRHRIQCWCFGUEQ-UHFFFAOYSA-N thioxanthen-9-one Chemical compound C1=CC=C2C(=O)C3=CC=CC=C3SC2=C1 YRHRIQCWCFGUEQ-UHFFFAOYSA-N 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
- 238000004642 transportation engineering Methods 0.000 description 1
- BYMUNNMMXKDFEZ-UHFFFAOYSA-K trifluorolanthanum Chemical compound F[La](F)F BYMUNNMMXKDFEZ-UHFFFAOYSA-K 0.000 description 1
- XRADHEAKQRNYQQ-UHFFFAOYSA-K trifluoroneodymium Chemical compound F[Nd](F)F XRADHEAKQRNYQQ-UHFFFAOYSA-K 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 238000001771 vacuum deposition Methods 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 239000000080 wetting agent Substances 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
- 229920001345 ε-poly-D-lysine Polymers 0.000 description 1
Abstract
The present invention relates to the field of and processes and printing apparatuses for producing optical effect layers (OEL) comprising magnetically oriented platelet-shaped magnetic or magnetizable pigment particles on a substrate. In particular, the present invention relates to processes using printing apparatuses comprising a first magnetic-field-generating device mounted on a transferring device (TD) and a static second magnetic-field-generating device for producing said OELs as anti-counterfeit means on security documents or security articles or for decorative purposes.
Description
PROCESSES FOR PRODUCING OPTICAL EFFECTS LAYERS
FIELD OF THE INVENTION
The présent invention relates to the field of processes and printing apparatuses for producing optical effect layers (OELs) comprising magnetically oriented platelet-shaped magnetic or magnetizable pigment particles. In particular, the présent invention provides processes and printing apparatuses for magnetically orienting platelet-shaped magnetic or magnetizable pigment particles in coating layer so as to produce OELs and the use of said OELs as anti-counterfeit means on security documents or security articles as well as décorative purposes.
BACKGROUND OF THE INVENTION
It is known in the art to use inks, compositions, coatings or layers containing oriented magnetic or magnetizable pigment particles, particularly also optically variable magnetic or magnetizable pigment particles, for the production of security éléments, e.g. in the field of security documents. Coatings or layers comprising oriented magnetic or magnetizable pigment particles are disclosed for example in US 2,570,856; US 3,676,273; US 3,791,864; US 5,630,877 and US 5,364,689. Coatings or layers comprising oriented magnetic color-shifting pigment particles, resulting in particularly appealing optical effects, useful for the protection of security documents, hâve been disclosed in WO 2002/090002 A2 and WO 2005/002866 A1.
Security features, e.g. for security documents, can generally be classified into “covert” security features on the one hand, and “overt” security features on the other hand. The protection provided by covert security features relies on the principle that such features are difficult to detect, typically requiring specialized equipment and knowledge for détection, whereas “overt” security features rely on the concept of being easily détectable with the unaided human senses, e.g. such features may be visible and/or détectable via the tactile sense while still being difficult to produce and/or to copy. However, the effectiveness of overt security features dépends to a great extent on their easy récognition as a security feature.
Magnetic or magnetizable pigment particles in printing inks or coatings allow for the production of magnetically induced images, designs and/or patterns through the application of a correspondingly structured magnetic field, inducing a local orientation of the magnetic or magnetizable pigment particles in the not yet hardened (i.e. wet) coating, followed by the hardening of the coating. The resuit is a fixed and stable magnetically induced image, design or pattern. Materials and technologies for the orientation of magnetic or magnetizable pigment particles in coating compositions hâve been disclosed for example in US 2,418,479; US 2,570,856; US 3,791,864, DE 2006848-A, US 3,676,273, US 5,364,689, US 6,103,361, EP 0 406 667 B1; US 2002/0160194; US 2004/0009308; EP 0 710 508 A1 ; WO 2002/09002 A2; WO 2003/000801 A2; WO 2005/002866 A1 ; WO 2006/061301 A1. In such a way, magnetically induced patterns which are highly résistant to counterfeit can be produced. The security element in question can only be produced by having access to both, the magnetic or magnetizable pigment particles or the corresponding ink, and the particular technology employed to print said ink and to orient said pigment in the printed ink.
The methods and devices described hereabove use magnetic assemblies to mono-axially orient platelet-shaped magnetic pigment particles. Mono-axial orientation of magnetic pigment particles resuit in neighboring particles having their main axis parallel to each other and to the magnetic field, while their minor axis in the plane of the pigment particles is not, or much less constrained by the applied magnetic field.
With the aim of producing coatings or layers comprising bi-axially oriented magnetic or magnetizable pigment particles, methods for generating time-dependent, direction-variable magnetic fields of sufficient intensity hâve been developed thus allowing the bis-axial orientation of magnetic or magnetizable pigment particles.
WO 2015/086257 A1 discloses an improved method for producing an optical effect layer (OEL) on a substrate, said process comprising two magnetic orientation steps, said steps consisting of i) exposing a coating composition comprising platelet-shaped magnetic or magnétisable pigment particles to a dynamic, i.e. direction changing, magnetic field of a first magnetic-field-generating device so as to bi-axially orient at least a part of the platelet-shaped magnetic or magnétisable pigment particles and ii) exposing the coating composition to a static magnetic field of a second magnetic-field-generating device, thereby mono-axially re-orienting at least a part of the plateletshaped magnetic or magnétisable pigment particles according to a design transferred by said second magnetic-field-generating device. Whereas the method disclosed in WO 2015/086257 A1 allows the production of optical effects layers exhibiting improved brightness and contrast compared to the prior art, said process requires two independent steps, wherein the first step requires additional space for the pre-alignment of the magnetic or magnetizable pigment particles. This requirement is cumbersome to be implemented in a high-speed industrial printing equipment since it requires additional space which is not easily accessible on currently printing equipments thus leading to the adaptation of the currently available used equipments and high costs.
Therefore, a need remains for improved processes for producing optical effect layers (OELs), said methods being mechanically robust, easy to implement with an industrial high-speed printing equipment, in particular rotating magnetic orienting cylinders, without resorting to cumbersome, tedious and expensive modifications of said equipment.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the présent invention to overcome the deficiencies of the prior art. This is achieved by the provision of a process for producing an optical effect layer (OEL) on a substrate (x10), said process comprising the steps of:
a) applying onto a substrate (x10) surface a coating composition comprising platelet-shaped magnetic or magnetizable pigment particles so as to form a coating layer (x20) on said substrate (x10), said coating composition being in a first State,
b) placing the substrate (x10) carrying the coating layer (x20) on a first magnetic-field-generating device (x30) providing a first magnetic field vector component, said first magnetic-field-generating device (x30) being mounted on a transferring device (TD) thereby subjecting the platelet-shaped magnetic or magnétisable pigment particles to said first magnetic field vector component, concomitantly moving said substrate (x10) carrying the coating layer (x20) and said first magneticfield-generating device (x30) in the vicinity of a static second magnetic-field-generating device (x40), said second magnetic-field-generating device (x40) providing a second magnetic field vector component thereby subjecting the platelet-shaped magnetic or magnétisable pigment particles to a timedependent résultant magnetic field formed by the first and second magnetic field vector components so as to bi-axially orient at least a part of the platelet-shaped magnetic or magnetizable pigment particles, and
c) hardening the coating composition to a second State so as to fix the platelet-shaped magnetic or magnetizable pigment particles in their adopted positions and orientations.
Also described herein are optical effect layers (OELs) produced by the process described herein and security documents as well as décorative éléments and objects comprising one or more optical OELs described herein.
Also described herein are methods of manufacturing a security document or a décorative element or object, comprising a) providing a security document or a décorative element or object, and b) providing an optical effect layer such as those described herein, in particular such as those obtained by the process described herein, so that it is comprised in the security document or décorative element or object.
Also described herein are printing apparatuses comprising the transferring device (TD) described herein, preferably the rotating magnetic cylinder (RMC) described herein, and at least one of the second magnetic-field-generating devices (x40) described herein, said transferring device (TD), preferably said rotating magnetic cylinder (RMC) comprising at least one of the first magnetic-fieldgenerating devices (x30) described herein and mounted thereon.
Also described herein are uses of the printing apparatuses for producing the optical effect layers (OELs) described herein.
The process provided by the présent invention is mechanically robust, easy to implement with an industrial high-speed printing equipment, without resorting to cumbersome, tedious and expensive modifications of said equipment.
BRIEF DESCRIPTION OF DRAWINGS
The optical effect layers (OEL) described herein and their production are now described in more detail with reference to the drawings and to particular embodiments, wherein
Fig. 1 schematically illustrâtes the exposure of a substrate (110) carrying a coating layer (120) to i) a first magnetic-field-generating device (130) being mounted on a transferring device (TD), in particular a rotating magnetic cylinder (RMC) and ii) a static second magnetic magnetic-fieldgenerating device (140), where the substrate (110) carrying a coating layer (120) concomitantly moves with the first magnetic-field-generating device (130) in the vicinity of the static second magnetic field generating device (140). The coating layer (120) is hardened with a hardening unit (150) so as to form an optical effect layer (OEL).
Fig. 2 schematically illustrâtes a top view of a combination comprising a first magnetic field generating device (230) providing a first time-independent magnetic field vector component and a static second magnetic field generating device (240) providing a second magnetic field vector component. The first magnetic field generating device (230) being a bar dipole magnet which synchronously and concomitantly moves with a substrate (210) carrying a coating layer (220) (not shown in Fig. 2) in the vicinity ofthe second magneticfield generating device (240).
Fig. 3 schematically illustrâtes the magnetic fields of a first magnetic field generating device (330) providing a first time-independent magnetic field vector component (H1), the magnetic fields of a second magnetic field generating device (340) providing a second magnetic field vector component (H2), and the résultant magnetic field (H3) formed by the first and second magnetic field vector components, i.e. resulting from the vector addition of H1 and H2.
Fig. 4A schematically illustrâtes a process for the orientation of platelet-shaped magnetic or magnetizable pigment particles comprised in a coating layer (420) on a substrate (410) using a transferring device (TD), in particular a linear magnetic transferring device (LMTD), according to the présent invention, said process comprising a step of concomitantly moving (see grey arrow) the substrate (410) carrying the coating layer (420) with a first magnetic-field-generating device (430) in the vicinity of a static second magnetic field generating device (440) comprising two dipole bar magnets (441a and 441b).
Fig. 4B schematically illustrâtes a cross-section of the first and second magnetic-field-generating devices (430, 440) of Fig. 4A. The bar dipole ofthe first magnetic-field-generating device (430) is comprised in a holder (431), wherein said holder is placed on top of a supporting block (432) and a rail (433). The two dipole bar magnets (441a and 441b) ofthe second magnetic-field-generating device (440) are inserted in two holders (442a and 442b) fixed on a frame (443a-c).
Fig. 4C schematically illustrâtes a cross-section of the first magnetic-field-generating device (430) of Fig. 4A-B. The first magnetic-field-generating device (430) is comprised in the holder (431) supported by the supporting block (432) and the rail (433) to be moveable in the vicinity of the static second magnetic-field-generating device, wherein the substrate (410) carrying the coating layer (420) is placed on top of said holder (431).
Fig. 5AB shows pictures of OELs prepared according to the présent invention (Fig. 5A) and prepared according to a comparative process (Fig. 5B).
DETAILED DESCRIPTION
Définitions
The following définitions are to be used to interpret the meaning of the terms discussed in the description and recited in the claims.
As used herein, the indefinite article a indicates one as well as more than one and does not necessarily limit its referent noun to the singular.
As used herein, the term “at least” is meant to define one or more than one, for example one or two or three.
As used herein, the term “about” means that the amount or value in question may be the spécifie value designated or some other value in its neighborhood. Generally, the term “about” denoting a certain value is intended to dénoté a range within ± 5% of the value. As one example, the phrase “about 100” dénotés a range of 100 ± 5, i.e. the range from 95 to 105. Generally, when the term “about” is used, it can be expected that similar results or effects according to the invention can be obtained within a range of±5% ofthe indicated value.
As used herein, the term “and/or” means that either ail or only one of the éléments of said group may be présent. For example, “A and/or B” shall mean “only A, or only B, or both A and B”. In the case of “only A”, the term also covers the possibility that B is absent, i.e. “only A, but not B”.
The term “comprising” as used herein is intended to be non-exclusive and open-ended. Thus, for instance a coating composition comprising a compound A may include other compounds besides A. However, the term “comprising” also covers, as a particular embodiment thereof, the more restrictive meanings of “consisting essentially of’ and “consisting of”, so that for instance “a coating composition comprising A, B and optionally C” may also (essentially) consist of A and B, or (essentially) consist of A, B and C.
The term “optical effect layer (OEL)” as used herein dénotés a coating or layer that comprises oriented platelet-shaped magnetic or magnetizable pigment particles and a binder, wherein said platelet-shaped magnetic or magnetizable pigment particles are oriented by a magnetic field and wherein the oriented platelet-shaped magnetic or magnetizable pigment particles are fixed/frozen in their orientation and position (i.e. after hardening/curing) so as to form a magnetically induced image.
The term coating composition refers to any composition which is capable of forming an optical effect layer (EOL) on a solid substrate and which can be applied preferably but not exclusively by a printing method. The coating composition comprises the platelet-shaped magnetic or magnetizable pigment particles described herein and the binder described herein.
As used herein, the term “wet” refers to a coating layer which is not yet cured, for example a coating in which the platelet-shaped magnetic or magnetizable pigment particles are still able to change their positions and orientations under the influence of extemal forces acting upon them.
As used herein, the term “indicia” shall mean discontinuous layers such as patterns, including without limitation symbols, alphanumeric symbols, motifs, letters, words, numbers, logos and drawings.
The term “hardening” is used to dénoté a process wherein the viscosity of a coating composition in a first physical state which is not yet hardened (i.e. wet) is increased so as to convert it into a second physical state, i.e. a hardened or solid state, where the platelet-shaped magnetic or magnetizable pigment particles are fixed/frozen in their current positions and orientations and can no longer move nor rotate.
The term security document refers to a document which is usually protected against counterfeit or fraud by at least one security feature. Examples of security documents include without limitation value documents and value commercial goods.
The term “security feature” is used to dénoté an image, pattern or graphie element that can be used for authentication purposes.
Where the présent description refers to “preferred” embodiments/features, combinations of these “preferred” embodiments/features shall also be deemed as disclosed as long as this combination of “preferred” embodiments/features is technically meaningful.
The présent invention provides processes for producing optical effect layers (OEL) on substrates.
The process according to the présent invention comprises the steps of:
a) applying onto the substrate (x10) surface described herein the coating composition comprising platelet-shaped magnetic or magnetizable pigment particles described herein so as to form the coating layer (x20) described herein on said substrate (x10), said coating composition being in a first state,
b) placing the substrate (x10) carrying the coating layer (x20) on the first magnetic-field-generating device (x30) described herein and providing the first magnetic field vector component described herein, said first magnetic-field-generating device (x30) being mounted on a transferring device (TD) thereby subjecting the platelet-shaped magnetic or magnétisable pigment particles to said first magnetic field vector component, concomitantly moving said substrate (x10) carrying the coating layer (x20) and said first magneticfield-generating device (x30) in the vicinity of the static (i.e. not moving with the transferring device (TD)), second magnetic-field-generating device (x40) described herein, said second magnetic-fieldgenerating device (x40) providing the second magnetic field vector component described herein thereby subjecting the platelet-shaped magnetic or magnétisable pigment particles to the timedependent résultant magnetic field formed by the first and second magnetic field vector components described herein so as to bi-axially orient at least a part of the platelet-shaped magnetic or magnetizable pigment particles, and
c) hardening the coating composition to a second state so as to fix the platelet-shaped magnetic or magnetizable pigment particles in their adopted positions and orientations.
The présent invention provides a reliable and easy to implement process to produce optical effect layers (OEL). The magnetic orientation of the platelet-shaped magnetic or magnetizable pigment particles on the substrate is carried out by placing the substrate (x10) carrying the coating layer (x20) comprising said platelet-shaped magnetic or magnetizable pigment particles on the first magnetic-field-generating device (x30) being mounted on the transferring device (TD) described herein, preferably the rotating magnetic cylinder (RMC) described herein, and submitting them to the static second magnetic-field-generating device, wherein the first magnetic-field-generating device (x30) and the substrate (x10) carrying the coating layer (x20) concomitantly move with the first magnetic-field-generating device (x30) and with the transferring device (TD) and wherein said second magnetic-field-generating device is a static device, i.e. does not move with the transferring device (TD).
Since the substrate (x10) carrying the coating layer (x20) concomitantly moves with the first magnetic-field-generating device (x30), said first magnetic-field-generating device (x30) providing a first time-independent magnetic field vector component, the platelet-shaped magnetic or magnétisable pigment particles are subjected to said first magnetic field vector component, wherein said first magnetic field vector component is time-independent in the reference frame ofthe coating layer, preferably time-independentwithin a plane which is fixed in the reference frame ofthe coating layer.
The présent invention takes advantage of the synchronous and concomitant movement of the substrate (x10) carrying the coating layer (x20) comprising platelet-shaped magnetic or magnetizable pigment particles with the first magnetic-field-generating device (x30) in the vicinity of the static second magnetic-field-generating device (x40), (i.e. through the magnetic field of the static second magnetic-field-generating device (x40), wherein said second magnetic-field-generating device (x40) does not move with the transferring device (TD) and provides a second magnetic field vector component. The résultant magnetic field formed by the first and second magnetic field vector components allow the bi-axial orientation of at least a part of the platelet-shaped magnetic or magnetizable pigment particles. During the process described herein, the platelet-shaped magnetic or magnetizable pigment particles are subjected to the time-dependent resulting magnetic field that is the vector sum of the first and second magnetic field vector components and move within said inhomogeneous resulting magnetic field. By “time-dependent magnetic field” it is meant that along the path of motion followed by individual platelet-shaped magnetic or magnetizable pigment particles of the coating layer, the magnetic field is time dépendent (i.e. time-varying) in direction or time dépendent (i.e. time-varying) in direction and intensity in the reference frame of the coating layer, preferably time-dependent (i.e. time-varying) within a plane which is fixed in the reference frame of the coating layer. In this way, at least a part of the platelet-shaped magnetic or magnetizable pigment particles of the coating layer tend to align, resulting in a bi-axial orientation of at least a part of said platelet-shaped magnetic or magnetizable particles, i.e. an orientation in which the two largest principal axes of said platelet-shaped pigment particles are constrained. Once the desired effect is created in the not yet hardened (i.e. wet) coating layer, the coating composition is partly or completely hardened so as to permanently fix/freeze the relative position and orientation of the platelet-shaped magnetic or magnetizable pigment particles in the OEL.
The transferring device (TD) described herein may be a rotating magnetic orienting cylinder (RMC) or a linear magnetic transferring device (LMTD) such as for example a linear guide. Preferably, the transferring device (TD) described herein is a rotating magnetic orienting cylinder (RMC).
As shown in Fig. 1, the first magnetic-field-generating device (x30) described herein is mounted on a transferring device (TD) being a rotating magnetic orienting cylinder (RMC) described herein, wherein said rotating magnetic orienting cylinder (RMC) is part of a rotary, sheet-fed or web-fed industrial printing press that opérâtes at high printing speed in a continuous way, in particular the first magnetic-field-generating device (x30) is mounted on circumferential grooves or transverse grooves of the rotating magnetic cylinder (RMC). The rotating magnetic orienting cylinder (RMC) comprising the first magnetic-field-generating device (x30) described herein is aimed to be used in, or in conjunction with, or being part of a printing or coating equipment comprising the static second magnetic-field-generating device (x40) described herein so as to orient platelet-shaped magnetic or magnetizable pigment particles in the coating layer.
The process described herein comprises a step a) of applying onto the substrate (x10) surface described herein the coating composition comprising platelet-shaped magnetic or magnetizable pigment particles described herein so as to form a coating layer (x20), said coating composition being in a first physical state which allows its application as a layer and which is in a not yet hardened (i.e. wet) state wherein the platelet-shaped magnetic or magnetizable pigment particles can move and rotate within the binder material. Since the coating composition described herein is to be provided on a substrate (x10) surface, the coating composition comprises at least a binder material such as those described herein and the platelet-shaped magnetic or magnetizable pigment particles, wherein said coating composition is in a form that allows its processing on the desired printing or coating equipment. Preferably, said step a) is carried out by a printing process, preferably selected from the group consisting of screen printing, rotogravure printing, flexography printing, inkjet printing and intaglio printing (also referred in the art as engraved copper plate printing and engraved steel die printing), more preferably selected from the group consisting of intaglio printing, screen printing, rotogravure printing and flexography printing and still more preferably selected from the group consisting of intaglio printing, screen printing, rotogravure printing and flexography printing.
Screen printing (also referred in the art as silkscreen printing) is a stencil process wherein an ink is transferred to a surface through a stencil supported by a fine fabric mesh of silk, mono- or multifilaments made of synthetic fibers such as for example polyamides or polyesters or métal threads stretched tightly on a frame made for example of wood or a métal (e.g. aluminum or stainless steel). Alternatively, the screen-printing mesh may be a chemically etched, a laser-etched, or a galvanically formed porous métal foil, e.g. a stainless steel foil. The pores of the mesh are blocked in the nonimage areas and left open in the image area, the image carrier being called the screen. Screen printing might be of the fiat-bed or rotary type. Screen printing is further described for example in The Printing ink manual, R.H. Leach and R.J. Pierce, Springer Edition, 5°1 Edition, pages 58-62 and in Printing Technology, J.M. Adams and P.A. Dolin, Delmar Thomson Learning, 5ω Edition, pages 293-328.
Rotogravure (also referred in the art as gravure) is a printing process wherein the image éléments are engraved into the surface of a cylinder. The non-image areas are at a constant original level. Prior to printing, the entire printing plate (non-printing and printing éléments) is inked and flooded with ink. Ink is removed from the non-image by a wiper or a blade before printing, so that ink remains only in the cells. The image is transferred from the cells to the substrate by a pressure typically in the range of 2 to 4 bars and by the adhesive forces between the substrate and the ink. The term rotogravure does not encompass intaglio printing processes (also referred in the art as engraved steel die or copper plate printing processes) which rely for example on a different type of ink. More details are provided in “Handbook of print media”, Helmut Kipphan, Springer Edition, page 48 and in The Printing ink manual, R.H. Leach and R.J. Pierce, Springer Edition, 5th Edition, pages 42-51. Flexography preferably uses a unit with a doctor blade, preferably a chambered doctor blade, an anilox roller and plate cylinder. The anilox roller advantageously has small cells whose volume and/or density détermines the ink application rate. The doctor blade lies against the anilox roller, and scraps off surplus ink at the same time. The anilox roller transfers the ink to the plate cylinder which finally transfers the ink to the substrate. Spécifie design might be achieved using a designed photopolymer plate. Plate cylinders can be made from polymeric or elastomeric materials. Polymers are mainly used as photopolymer in plates and sometimes as a seamless coating on a sleeve. Photopolymer plates are made from light-sensitive polymers that are hardened by ultraviolet (UV) light. Photopolymer plates are eut to the required size and placed in an UV light exposure unit. One side of the plate is completely exposed to UV light to harden or cure the base of the plate. The plate is then turned over, a négative of the job is mounted over the uncured side and the plate is further exposed to UV light. This hardens the plate in the image areas. The plate is then processed to remove the unhardened photopolymer from the nonimage areas, which lowers the plate surface in these nonimage areas. After processing, the plate is dried and given a post-exposure dose of UV light to cure the whole plate. Préparation of plate cylinders for flexography is described in Printing Technology, J. M. Adams and P.A. Dolin, Delmar Thomson Learning, 5th Edition, pages 359-360 and in The Printing ink manual, R.H. Leach and R.J. Pierce, Springer Edition, 5th Edition, pages 3342.
The coating composition described herein as well as the coating layer (x20) described herein comprise platelet-shaped magnetic or magnetizable pigment particles. Preferably, the plateletshaped magnetic or magnetizable pigment particles described herein are présent in an amount from about 5 wt-% to about 40 wt-%, more preferably about 10 wt-% to about 30 wt-%, the weight percentages being based on the total weight of the coating composition.
In contrast to needle-shaped pigment particles which can be considered as quasi one-dimensional particles, platelet-shaped pigment particles are quasi two-dimensional particles due to the large aspect ratio of their dimensions. Platelet-shaped pigment particle can be considered as a twodimensional structure wherein the dimensions X and Y are substantially larger than the dimension Z. Platelet-shaped pigment particles are also referred in the art as oblate particles or flakes. Such pigment particles may be described with a main axis X corresponding to their longest dimension Crossing the pigment particle and a second axis Y perpendicular to X and Crossing the pigment particle. In other words, the XY plane roughly defines the plane formed by the first and second longest dimensions of the pigment particle, the Z dimension being ignored.
The platelet-shaped magnetic or magnetizable pigment particles described herein hâve, due to their non-spherical shape, non-isotropic reflectivity with respect to incident electromagnetic radiation for which the hardened/cured binder material is at least partially transparent. As used herein, the term “non-isotropic reflectivity” dénotés that the proportion of incident radiation from a first angle that is reflected by a particle into a certain (viewing) direction (a second angle) is a function of the orientation of the particles, i.e. that a change ofthe orientation ofthe particle with respect to the first angle can lead to a different magnitude of the reflection to the viewing direction.
The OEL described herein comprises platelet-shaped magnetic or magnetizable pigment particles that, due to their shape, hâve non-isotropic reflectivity. In the OELs described herein, the plateletshaped magnetic or magnetizable pigment particles described herein are dispersed in the coating composition comprising a hardened binder material thatfixes the orientation ofthe platelet-shaped magnetic or magnetizable pigment particles. The binder material is at least in its hardened or solid state (also referred to as second state herein), at least partially transparent to electromagnetic radiation of a range of wavelengths comprised between 200 nm and 2500 nm, i.e. within the wavelength range which is typically referred to as the “optical spectrum and which comprises infrared, visible and UV portions of the electromagnetic spectrum. Accordingly, the particles contained in the binder material in its hardened or solid state and their orientation-dependent reflectivity can be perceived through the binder material at some wavelengths within this range. Preferably, the hardened binder material is at least partially transparent to electromagnetic radiation of a range of wavelengths comprised between 200 nm and 800 nm, more preferably comprised between 400 nm and 700 nm. Herein, the term “transparent” dénotés that the transmission of electromagnetic radiation through a layer of 20 pm of the hardened binder material as présent in the OEL (not including the platelet-shaped magnetic or magnetizable pigment particles, but ail other optional components of the OEL in case such components are présent) is at least 50%, more preferably at least 60 %, even more preferably at least 70%, at the wavelength(s) concerned. This can be determined for example by measuring the transmittance of a test piece of the hardened binder material (not including the platelet-shaped magnetic or magnetizable pigment particles) in accordance with well-established test methods, e.g. DIN 5036-3 (1979-11). If the OEL serves as a covert security feature, then typically technical means will be necessary to detect the (complété) optical effect generated by the OEL under respective ilIuminating conditions comprising the selected non-visible wavelength; said détection requiring that the wavelength of incident radiation is selected outside the visible range, e.g. in the near UV-range.
Suitable examples of platelet-shaped magnetic or magnetizable pigment particles described herein include without limitation pigment particles comprising a magnetic métal selected from the group consisting of cobalt (Co), iron (Fe), and nickel (Ni); a magnetic alloy of iron, manganèse, cobalt, nickel or a mixture of two or more thereof; a magnetic oxide of chromium, manganèse, cobalt, iron, nickel or a mixture of two or more thereof; or a mixture of two or more thereof. The term “magnetic” in reference to the metals, alloys and oxides is directed to ferromagnetic or ferrimagnetic metals, alloys and oxides. Magnetic oxides of chromium, manganèse, cobalt, iron, nickel or a mixture of two or more thereof may be pure or mixed oxides. Examples of magnetic oxides include without limitation iron oxides such as hématite (Fe2O3), magnetite (Fe3O4), chromium dioxide (CrO2), magnetic ferrites (MFe2O4), magnetic spinels (MR2O4), magnetic hexaferrites (MFe^Oig), magnetic orthoferrites (RFeOa), magnetic gamets MaRafAO^a, wherein M stands for two-valent métal, R stands for three-valent métal, and A stands for four-valent métal.
Examples of platelet-shaped magnetic or magnetizable pigment particles described herein include without limitation pigment particles comprising a magnetic layer M made from one or more of a magnetic métal such as cobalt (Co), iron (Fe), or nickel (Ni); and a magnetic alloy of iron, cobalt or nickel, wherein said magnetic or magnetizable pigment particles may be multilayered structures comprising one or more additional layers. Preferably, the one or more additional layers are layers A independently made from one or more selected from the group consisting of métal fluorides such as magnésium fluoride (MgF2), silicium oxide (SiO), silicium dioxide (S1O2), titanium oxide (TiO2), and aluminum oxide (AI2O3), more preferably silicium dioxide (S1O2); or layers B independently made from one or more selected from the group consisting of metals and métal alloys, preferably selected from the group consisting of reflective metals and reflective métal alloys, and more preferably selected from the group consisting of aluminum (Al), chromium (Cr), and nickel (Ni), and still more preferably aluminum (Al); or a combination of one or more layers A such as those described hereabove and one or more layers B such as those described hereabove. Typical examples of the platelet-shaped magnetic or magnetizable pigment particles being multilayered structures described hereabove include without limitation A/M multilayer structures, A/M/A multilayer structures, A/M/B multilayer structures, A/B/M/A multilayer structures, A/B/M/B multilayer structures, A/B/M/B/A/multilayer structures, B/M multilayer structures, B/M/B multilayer structures, B/A/M/A multilayer structures, B/A/M/B multilayer structures, B/A/M/B/A/multilayer structures, wherein the layers A, the magnetic layers M and the layers B are chosen from those described hereabove.
The coating composition described herein may comprise platelet-shaped optically variable magnetic or magnetizable pigment particles, and/or platelet-shaped magnetic or magnetizable pigment particles having no optically variable properties. Preferably, at least a part of the platelet-shaped magnetic or magnetizable pigment particles described herein is constituted by platelet-shaped optically variable magnetic or magnetizable pigment particles. In addition to the overt security provided by the colorshifting property of the optically variable magnetic or magnetizable pigment particles, which allows easily detecting, recognizing and/or discriminating an article or security document carrying an ink, coating composition, or coating layer comprising the optically variable magnetic or magnetizable pigment particles described herein from their possible counterfeits using the unaided human senses, the optical properties ofthe optically variable magnetic or magnetizable pigment particles may also be used as a machine readable tool for the récognition ofthe OEL. Thus, the optical properties of the optically variable magnetic or magnetizable pigment particles may simultaneously be used as a covert or semi-covert security feature in an authentication process wherein the optical (e.g. spectral) properties of the pigment particles are analyzed.
The use of platelet-shaped optically variable magnetic or magnetizable pigment particles in coating layers for producing an OEL enhances the significance of the OEL as a security feature in security document applications, because such materials are reserved to the security document printing industry and are not commercially available to the public.
As mentioned above, preferably at least a part of the platelet-shaped magnetic or magnetizable pigment particles is constituted by platelet-shaped optically variable magnetic or magnetizable pigment particles. These are more preferably selected from the group consisting of magnetic thinfilm interférence pigment particles, magnetic cholesteric liquid crystal pigment particles, interférence coated pigment particles comprising a magnetic material and mixtures of two or more thereof.
Magnetic thin film interférence pigment particles are known to those skilled in the art and are disclosed e.g. in US 4,838,648; WO 2002/073250 A2; EP 0 686 675 B1; WO 2003/000801 A2; US 6,838,166; WO 2007/131833 A1 ; EP 2 402 401 A1 and in the documents cited therein. Preferably, the magnetic thin film interférence pigment particles comprise pigment particles having a five-layer Fabry-Perot multilayer structure and/or pigment particles having a six-layer Fabry-Perot multilayer structure and/or pigment particles having a seven-layer Fabry-Perot multilayer structure.
Preferred five-layer Fabry-Perot multilayer structures consist of absorber/dielectric/reflector/dielectric/absorber multilayer structures wherein the reflector and/or the absorber is also a magnetic layer, preferably the reflector and/or the absorber is a magnetic layer comprising nickel, iron and/or cobalt, and/or a magnetic alloy comprising nickel, iron and/or cobalt and/or a magnetic oxide comprising nickel (Ni), iron (Fe) and/or cobalt (Co).
Preferred six-layer Fabry-Perot multilayer structures consist of absorber/dielectric/reflector/magnetic/dielectric/absorber multilayer structures.
Preferred seven-layer Fabry Perot multilayer structures consist of absorber/dielectric/reflector/magnetic/reflector/dielectric/absorber multilayer structures such as disclosed in US 4,838,648.
Preferably, the reflector layers described herein are independently made from one or more selected from the group consisting of metals and métal alloys, preferably selected from the group consisting of reflective metals and reflective métal alloys, more preferably selected from the group consisting of aluminum (Al), silver (Ag), copper (Cu), gold (Au), platinum (Pt), tin (Sn), titanium (Ti), palladium (Pd), rhodium (Rh), niobium (Nb), chromium (Cr), nickel (Ni), and alloys thereof, even more preferably selected from the group consisting of aluminum (Al), chromium (Cr), nickel (Ni) and alloys thereof, and still more preferably aluminum (Al). Preferably, the dielectric layers are independently made from one or more selected from the group consisting of métal fiuorides such as magnésium fluoride (MgF2), aluminum fluoride (AIF3), cérium fluoride (CeFs), lanthanum fluoride (LaFs), sodium aluminum fiuorides (e.g. NasAIFe), neodymium fluoride (NdFs), samarium fluoride (SmFs), barium fluoride (BaF2), calcium fluoride (CaF2), lithium fluoride (LiF), and métal oxides such as silicium oxide (SiO), silicium dioxide (S1O2), titanium oxide (T1O2), aluminum oxide (AI2O3), more preferably selected from the group consisting of magnésium fluoride (MgF2) and silicium dioxide (S1O2) and still more preferably magnésium fluoride (MgF2). Preferably, the absorber layers are independently made from one or more selected from the group consisting of aluminum (Al), silver (Ag), copper (Cu), palladium (Pd), platinum (Pt), titanium (Ti), vanadium (V), iron (Fe) tin (Sn), tungsten (W), molybdenum (Mo), rhodium (Rh), Niobium (Nb), chromium (Cr), nickel (Ni), métal oxides thereof, métal sulfides thereof, métal carbides thereof, and métal alloys thereof, more preferably selected from the group consisting of chromium (Cr), nickel (Ni), métal oxides thereof, and métal alloys thereof, and still more preferably selected from the group consisting of chromium (Cr), nickel (Ni), and métal alloys thereof. Preferably, the magnetic layer comprises nickel (Ni), iron (Fe) and/or cobalt (Co); and/or a magnetic alloy comprising nickel (Ni), iron (Fe) and/or cobalt (Co); and/or a magnetic oxide comprising nickel (Ni), iron (Fe) and/or cobalt (Co). When magnetic thin film interférence pigment particles comprising a seven-layer Fabry-Perot structure are preferred, it is particularly preferred that the magnetic thin film interférence pigment particles comprise a seven-layer FabryPerot absorber/dielectric/reflector/magnetic/reflector/dielectric/absorber multilayer structure consisting of a Cr/MgF2/AI/Ni/AI/MgF2/Cr multilayer structure.
The magnetic thin film interférence pigment particles described herein may be multilayer pigment particles being considered as safe for human health and the environment and being based for example on five-layer Fabry-Perot multilayer structures, six-layer Fabry-Perot multilayer structures and seven-layer Fabry-Perot multilayer structures, wherein said pigment particles include one or more magnetic layers comprising a magnetic alloy having a substantially nickel-free composition including about 40 wt-% to about 90 wt-% iron, about 10 wt-% to about 50 wt-% chromium and about 0 wt-% to about 30 wt-% aluminum. Typical examples of multilayer pigment particles being considered as safe for human health and the environment can be found in EP 2 402 401 A1 whose content is hereby incorporated by reference in its entirety.
Magnetic thin film interférence pigment particles described herein are typically manufactured by a conventional déposition technique of the different required layers onto a web. After déposition of the desired number of layers, e.g. by physical vapor déposition (PVD), Chemical vapor déposition (CVD) or electrolytic déposition, the stack of layers is removed from the web, either by dissolving a release layer in a suitable solvent, or by stripping the material from the web. The so-obtained material is then broken down to flakes which hâve to be further processed by grinding, milling (such as for example jet milling processes) or any suitable method so as to obtain pigment particles of the required size. The resulting product consists of fiat flakes with broken edges, irregular shapes and different aspect ratios. Further information on the préparation of suitable magnetic thin film interférence pigment particles can be found e.g. in EP 1 710 756 A1 and EP 1 666 546 A1 whose contents are hereby incorporated by reference.
Suitable magnetic cholesteric liquid crystal pigment particles exhibiting optically variable characteristics include without limitation magnetic monolayered cholesteric liquid crystal pigment particles and magnetic multilayered cholesteric liquid crystal pigment particles. Such pigment particles are disclosed for example in WO 2006/063926 A1, US 6,582,781 and US 6,531,221. WO 2006/063926 A1 discloses monolayers and pigment particles obtained therefrom with high brilliance and colorshifting properties with additional particular properties such as magnetizability. The disclosed monolayers and pigment particles, which are obtained therefrom by comminuting said monolayers, include a three-dimensionally crosslinked cholesteric liquid crystal mixture and magnetic nanoparticles. US 6,582,781 and US 6,410,130 disclose platelet-shaped cholesteric multilayer pigment particles which comprise the sequence A1/B/A2, wherein A1 and A2 may be identical or different and each comprises at least one cholesteric layer, and B is an interlayer absorbing ail or some of the light transmitted by the layers A1 and A2 and imparting magnetic properties to said interlayer. US 6,531,221 discloses platelet-shaped cholesteric multilayer pigment particles which comprise the sequence A/B and optionally C, wherein A and C are absorbing layers comprising pigment particles imparting magnetic properties, and B is a cholesteric layer.
Suitable interférence coated pigments comprising one or more magnetic materials include without limitation structures consisting of a substrate selected from the group consisting of a core coated with one or more layers, wherein at least one of the core or the one or more layers hâve magnetic properties. For example, suitable interférence coated pigments comprise a core made of a magnetic material such as those described hereabove, said core being coated with one or more layers made of one or more métal oxides, or they hâve a structure consisting of a core made of synthetic or natural micas, layered silicates (e.g. talc, kaolin and sericite), glasses (e.g. borosilicates), silicium dioxides (SiO2), aluminum oxides (AI2O3), titanium oxides (T1O2), graphites and mixtures of two or more thereof. Furthermore, one or more additional layers such as coloring layers may be présent. The magnetic or magnetizable pigment particles described herein may be surface treated so as to protect them against any détérioration that may occur in the coating composition and coating layer and/or to facilitate their incorporation in said coating composition and coating layer; typically corrosion inhibitor materials and/or wetting agents may be used.
Further, subsequently to the application of the coating composition described herein on the substrate surface described herein so as to form a coating layer (step a)), the substrate carrying the coating layer is arranged on top of the first magnetic-field-generating device (x30) being mounted on the transferring device (TD) described herein, preferably on the rotating magnetic cylinder (RMC) described herein. The substrate (x10) carrying the coating layer (x20) may be directly arranged on top of the first magnetic-field-generating device (x30), i.e. the substrate is in direct contact with the first magnetic-field-generating device (x30) or a gap may be présent between the substrate (x10) and the first magnetic-field-generating device (x30).
According to one embodiment and as shown in Fig. 4A-C, the substrate (x10) carrying the coating layer (x20) is arranged on top ofthe first magnetic-field-generating device (x30) with a gap between the substrate (x10) and the first magnetic-field-generating device (x30), wherein said gap may be obtained by using one or more holders, one or more plates or one or more spacers (x31). The holder, the plate or the one or more spacers (x31 ) is/are independently preferably made from one or more non-magnetic materials selected from the group consisting of low conducting materials, non-conducting materials and mixtures thereof, such as for example engineering plastics and polymers, titanium, titanium alloys and austenitic steels (i.e. non-magnetic steels). Engineering plastics and polymers include without limitation polyaryletherketones (PAEK) and its dérivatives polyetheretherketones (PEEK), poletherketoneketones (PEKK), polyetheretherketoneketones (PEEKK) and polyetherketoneetherketoneketone (PEKEKK); polyacetals, polyamides, polyesters, polyethers, copolyetheresters, polyimides, polyetherimides, high-density polyethylene (HDPE), ultra-high molecular weight polyethylene (UHMWPE), polybutylene terephthalate (PBT), polypropylene, acrylonitrile butadiene styrene (ABS) copolymer, fluorinated and perfluorinated polyethylenes, polystyrènes, polycarbonates, polyphenylenesulfide (PPS) and liquid crystal polymers. Preferred materials are PEEK (polyetheretherketone), POM (polyoxymethylene), PTFE (polytetrafiuoroethylene), Nylon® (polyamide) and PPS. Preferably, the holder, the plate or the one or more spacers (x31) is/are independently made of one more titanium-based materials since said materials hâve the advantage of excellent mechanical stability and low electric conductivity. The holder, the plate or one or more spacers (x31) may also be made of aluminum or aluminum alloys which hâve the advantage of being easily worked.
While the substrate (x10) carrying the coating layer (x20) is on top of the first magnetic-fieldgenerating device (x30), said coating layer (x20) is exposed to the magnetic field of the static second magnetic-field-generating device (x40).
The process described herein comprises a step of hardening the coating layer (x20) in a first State to a second State so as to fix/freeze the platelet-shaped magnetic or magnetizable pigment particles in their adopted positions and orientations. The hardening step is carried out by using a hardening unit (x50). The coating composition described herein must thus noteworthy hâve a first State, i.e. a liquid or pasty State, wherein the coating composition is not yet hardened and wet or soft enough, so that the platelet-shaped magnetic or magnetizable pigment particles dispersed in the coating composition are freely movable, rotatable and orientable upon exposure to a magnetic field, and a second hardened (e.g. solid or solid-like) State, wherein the platelet-shaped magnetic or magnetizable pigment particles are fixed or frozen in their respective positions and orientations.
Such a first and second state is preferably provided by using a certain type of coating composition. For example, the components of the coating composition other than the platelet-shaped magnetic or magnetizable pigment particles may take the form of an ink or coating composition such as those which are used in security applications, e.g. for banknote printing. The aforementioned first and second States .can be provided by using a material that shows an increase in viscosity in reaction to a stimulus such as for example a température change or an exposure to an electromagnetic radiation. That is, when the fluid binder material is hardened or solidified, said binder material converts into the second state, i.e. a hardened or solid state, where the platelet-shaped magnetic or magnetizable pigment particles are fixed in their current positions and orientations and can no longer move nor rotate within the binder material. As known to those skilled in the art, ingrédients comprised in an ink or coating composition to be applied onto a surface such as a substrate and the physical properties of said ink or coating composition must fulfill the requirements ofthe process used to transfer the ink or coating composition to the substrate surface. Consequently, the binder material comprised in the coating composition described herein is typically chosen among those known in the art and dépends on the coating or printing process used to apply the ink or coating composition and the chosen hardening process.
The hardening step generally may be any step that increases the viscosity of the coating composition such that a substantially solid material adhering to the substrate is formed. The hardening step may involve a physical process based on the évaporation of a volatile component, such as a solvent, and/or water évaporation (i.e. physical drying). Herein, hot air, infrared or a combination of hot air and infrared may be used. Alternatively, the hardening process may include a Chemical reaction, such as a curing, polymerizing or cross-linking of the binder and optional initiator compounds and/or optional cross-linking compounds comprised in the coating composition. Such a Chemical reaction may be initiated by heat or IR irradiation as outlined above for the physical hardening processes, but may preferably include the initiation of a Chemical reaction by a radiation mechanism including without limitation Ultraviolet-Visible light radiation curing (hereafter referred as UV-Vis curing) and electronic beam radiation curing (E-beam curing); oxypolymerization (oxidative réticulation, typically induced by a joint action of oxygen and one or more catalysts preferably selected from the group consisting of cobalt-containing catalysts, vanadium-containing catalysts, zirconium-containing catalysts, bismuth-containing catalysts and manganese-containing catalysts); cross-linking reactions or any combination thereof.
The hardening step described herein (step c)) can be of purely physical nature, e.g. in cases where the coating composition comprises a polymeric binder material and a solvent and is applied at high températures. Then, the platelet-shaped magnetic or magnetizable pigment particles are oriented at high température by the application of a magnetic field, and the solvent is evaporated, followed by cooling of the coating composition. Thereby the coating composition is hardened and the orientation of the pigment particles is fixed.
Alternatively and preferably, the hardening of the coating composition involves a Chemical reaction, for instance by curing, which is not reversed by a simple température increase (e.g. up to 80°C) that may occur during a typical use of a security document. The term “curing” or “curable” refers to processes including the Chemical reaction, crosslinking or polymerization of at least one component in the applied coating composition in such a manner that it turns into a polymeric material having a greater molecular weight than the starting substances. Preferably, the curing causes the formation of a stable three-dimensional polymeric network. Such a curing is generally induced by applying an external stimulus to the coating composition. Preferably, the coating composition is selected from the group consisting of radiation curable compositions, thermally drying compositions, oxidatively drying compositions, and combinations thereof.
Radiation curing is particularly preferred, and UV-Vis light radiation curing is even more preferred, since these technologies advantageously lead to very fast curing processes and hence drastically decrease the préparation time of any article comprising the OEL described herein. Moreover, radiation curing has the advantage of producing an almost instantaneous increase in viscosity of the coating composition after exposure to the curing radiation, thus minimizing any further movement of the particles. In conséquence, any loss of orientation after the magnetic orientation step can essentially be avoided. Particularly preferred is radiation-curing by photo-polymerization, under the influence of actinie light having a wavelength component in the UV or blue part of the electromagnetic spectrum (typically 200 nm to 650 nm; more preferably 200 nm to 420 nm).
Equipment for UV-visible-curing may comprise a high-power light-emitting-diode (LED) lamp, or an arc discharge lamp, such as a medium-pressure mercury arc (MPMA) or a metal-vapor arc lamp, as the source of the actinie radiation. Accordingly, particularly preferred are coating compositions selected from the group consisting of radiation curable compositions. Radiation curing, in particular UV-Vis curing, advantageously leads to an instantaneous increase in viscosity of the coating composition after exposure to the irradiation, thus preventing any further movement of the pigment particles and in conséquence any loss of information after the magnetic orientation step. Preferably, the hardening step (step c)) is carried out by irradiation with UV-visible light (i.e. UV-Vis light radiation curing) or by E-beam (i.e. E-beam radiation curing), more preferably by irradiation with UV-Vis light.
Therefore, suitable coating compositions for the présent invention include radiation curable compositions that may be cured by UV-visible light radiation (hereafter referred as UV-Vis-curable) or by E-beam radiation (hereafter referred as EB). According to one particularly preferred embodiment ofthe présent invention, the coating composition described herein is a UV-Vis-curable coating composition. UV-Vis curing advantageously allows very fast curing processes and hence drastically decreases the préparation time of the OEL described herein, documents and articles and documents comprising said OEL.
Preferably, the UV-Vis-curable coating composition comprises one or more compounds selected from the group consisting of radically curable compounds and cationically curable compounds. The UV-Vis-curable coating composition described herein may be a hybrid System and comprise a mixture of one or more cationically curable compounds and one or more radically curable compounds. Cationically curable compounds are cured by cationic mechanisms typically including the activation by radiation of one or more photoinitiators which liberate cationic species, such as acids, which in turn initiate the curing so as to react and/or cross-link the monomers and/or oligomers to thereby harden the coating composition. Radically curable compounds are cured by free radical mechanisms typically including the activation by radiation of one or more photoinitiators, thereby generating radicals which in turn initiate the polymerization so as to harden the coating composition. Depending on the monomers, oligomers or prepolymers used to préparé the binder comprised in the UV-Vis-curable coating compositions described herein, different photoinitiators might be used. Suitable examples of free radical photoinitiators are known to those skilled in the art and include without limitation acetophenones, benzophenones, benzyldimethyl ketals, alphaaminoketones, alpha-hydroxyketones, phosphine oxides and phosphine oxide dérivatives, as well as mixtures of two or more thereof. Suitable examples of cationic photoinitiators are known to those skilled in the art and include without limitation onium salts such as organic iodonium salts (e.g. diaryl iodoinium salts), oxonium (e.g. triaryloxonium salts) and sulfonium salts (e.g. triarylsulphonium salts), as well as mixtures of two or more thereof. Other examples of useful photoinitiators can be found in standard textbooks. It may also be advantageous to include a sensitizer in conjunction with the one or more photoinitiators in order to achieve efficient curing. Typical examples of suitable photosensitizers include without limitation isopropyl-thioxanthone (ITX), 1-chloro-2-propoxy17 thioxanthone (CPTX), 2-chloro-thioxanthone (CTX) and 2,4-diethyl-thioxanthone (DETX) and mixtures of two or more thereof. The one or more photoinitiators comprised in the UV-Vis-curable coating compositions are preferably présent in a total amount from about 0.1 wt-% to about 20 wt-%, more preferably about 1 wt-% to about 15 wt-%, the weight percents being based on the total weight of the UV-Vis-curable coating compositions.
Alternatively, a polymeric thermoplastic binder material or a thermoset may be employed. Unlike thermosets, thermoplastic resins can be repeatedly melted and solidified by heating and cooling without incurring any important changes in properties. Typical examples of thermoplastic resin or polymer include without limitation polyamides, polyesters, polyacetals, polyolefins, styrenic polymers, polycarbonates, polyarylates, polyimides, polyether ether ketones (PEEK), polyetherketeoneketones (PEKK), polyphenylene based resins (e.g. polyphenylenethers, polyphenylene oxides, polyphenylene sulfides), polysulphones and mixtures of two or more thereof. The process for producing the OEL described herein comprises partially simultaneously with step b) or subsequently to step b), preferably partially simultaneously, a step of hardening (step c)) the coating composition. The step of hardening the coating composition allows the platelet-shaped magnetic or magnetizable pigment particles to be fixed in their adopted positions and orientations in a desired pattern to form the OEL, thereby transforming the coating composition to the second state described herein. However, the time from the end of step b) to the beginning of step c) is preferably relatively short in order to avoid any de-orientation and loss of information. Typically, the time between the end of step b) and the beginning of step c) is less than 1 minute, preferably less than 20 seconds, further preferably less than 5 seconds. It is particularly préférable that there is essentially no time gap between the end of the orientation step b) and the beginning of the curing step c), i.e. that step c) follows immediately after step b) or already starts while step b) is still in progress (partially simultaneously). By “partially simultaneously”, it is meant that both steps are partly performed simultaneously, i.e. the times of performing each ofthe steps partially overlap. In the context described herein, when hardening is performed partially simultaneously with the step b), it must be understood that hardening becomes effective after the orientation process has started so that the platelet-shaped magnetic or magnetizable pigment particles orient before the complété or partial hardening of the OEL, in particular when the résultant magnetic field (H3) formed by the first and second magnetic field vector components (i.e. resulting from the vector addition of H1 and H2) described herein is greater than zéro, preferably greater than 50 mT. As mentioned herein, the hardening step (step c)) may be performed by using different means or processes depending on the binder material comprised in the coating composition that also comprises the platelet-shaped magnetic or magnetizable pigment particles.
The coating composition described herein may further comprise one or more coloring components selected from the group consisting of organic pigment particles, inorganic pigment particles, and organic dyes, and/or one or more additives. The latter include without limitation compounds and materials that are used foradjusting physical, rheological and Chemical parameters ofthe coating composition such as the viscosity (e.g. solvents, thickeners and surfactants), the consistency (e.g.
anti-settling agents, fillers and plasticizers), the foaming properties (e.g. antifoaming agents), the lubricating properties (waxes, oils), UV stability (photostabilizers), the adhesion properties, the antistatic properties, the storage stability (polymerization inhibitors) etc. Additives described herein may be présent in the coating composition in amounts and in forms known in the art, including socalled nano-materials where at least one of the dimensions of the additive is in the range of 1 to 1000 nm.
The coating composition described herein may further comprise one or more additives including without limitation compounds and materials which are used for adjusting physical, rheological and Chemical parameters of the composition such as the viscosity (e.g. solvents and surfactants), the consistency (e.g. anti-settling agents, fillers and plasticizers), the foaming properties (e.g. antifoaming agents), the lubricating properties (waxes), UV reactivity and stability (photosensitizers and photostabilizers) and adhesion properties, etc. Additives described herein may be présent in the coating compositions described herein in amounts and in forms known in the art, including in the form of so-called nano-materials where at least one of the dimensions of the particles is in the range of 1 to 1000 nm.
The coating composition described herein may further comprise one or more marker substances or taggants and/or one or more machine readable materials selected from the group consisting of magnetic materials (different from the magnetic or magnetizable pigment particles described herein), luminescent materials, electrically conductive materials and infrared-absorbing materials. As used herein, the term “machine readable material” refers to a material which exhibits at least one distinctive property which is détectable by a device or a machine, and which can be comprised in a coating so as to confer a way to authenticate said coating or article comprising said coating by the use of a particular equipment for its détection and/or authentication.
The coating compositions described herein may be prepared by dispersing or mixing the magnetic or magnetizable pigment particles described herein and the one or more additives when présent in the presence of the binder material described herein, thus forming liquid compositions. When présent, the one or more photoinitiators may be added to the composition either during the dispersing or mixing step of ail other ingrédients or may be added at a later stage, i.e. after the formation of the liquid coating composition.
While the substrate (x10) carrying the coating layer (x20) is concomitantly moving with the first magnetic-field-generating device (x30), the process described herein comprises a step of moving them in the vicinity of the static second magnetic-field-generating device (x40) described herein, wherein the substrate (x10) carrying the coating layer (x20) is arranged on top of the first magneticfield-generating device (x30). As shown in Fig 2 and 3, the first magnetic-field-generating device (x30) provides a first magnetic field vector component which is time-independent in the reference frame of the coating layer, preferably time-independent within a plane which is fixed in the reference frame of the coating layer (x20).
The substrate (x10) carrying the coating layer (x20) described herein and the first magnetic-fieldgenerating device (x30) synchronously and concomitantly move in the vicinity of the static (i.e. not moving with the transferring device (TD)), second magnetic-field-generating device (x40) (i.e. through the magnetic field of the static, i.e. not moving with the transferring device (TD) described herein, second magnetic-field-generating device (x40)) providing a second magnetic field vector component which is time-dependent in the reference frame of the coating layer (x20), preferably time-dependent within a plane which is fixed in the reference frame of the coating layer (x20), since the coating layer (x20) is moving in the vicinity of said static second magnetic-field-generating device (x40). The platelet-shaped magnetic or magnetizable pigment particles are thereby subjected/exposed to a résultant magnetic field formed by the first and second magnetic field vector components, said résultant magnetic field being time-dependent (time-varying) in direction or timedependent (time-varying) in direction and intensity (see Fig. 3), thus bi-axially orienting at least a part of said platelet-shaped magnetic or magnetizable pigment particles while the coating composition is still in a wet (i.e. not yet hardened) state.
As shown in Fig. 3, the first magnetic field vector component (H1) of the first magnetic field generating device (330) is constant over the time in the reference frame of the coating layer and is moving (as illustrated by the sériés of arrows in Fig. 3) concomitantly and synchronously with the substrate (x10) carrying the coating layer (x20) in the reference frame of second magnetic field generating device. The second magnetic field vector component (H2) of the second magnetic field generating device (340) is substantially non-parallel to the first magnetic field vector component (H1), preferably substantially perpendicular to the first magnetic field vector component (H1) of the of first magnetic field generating device (330). The second magnetic field vector component (H2) of the second magnetic field generating device (340) varies in intensity (alternatively varies in intensity and direction) over the space, the maximum intensity (H2max) being in the center of the two dipole bar magnets depicted in Fig 2. (241a and 241b, Fig. 2). Thus a substrate (x10) carrying a coating layer (x20) moving in the vicinity of the second magnetic field generating device (x40) will be subjected to a timely variable (H2) intensity as a resuit of the movement of said substrate. When the substrate (x10) carrying the coating layer (x20) and the first magnetic field generating device (330) concomitantly move in the vicinity of the second magnetic field generating device (340), the platelet-shaped magnetic or magnetizable pigment particles comprised in the coating layer (x20) are subjected to the inhomogeneous résultant magnetic field (H3) formed by the first and second magnetic field vector components, i.e. resulting from the vector addition of H1 and H2, i.e. they are subjected to a time-dependent magnetic field which varies at least in direction or varies in direction and intensity (see Fig. 3) in the reference frame of the coating layer, preferably time-dependent within a plane which is fixed in the reference frame of the coating layer thus bi-axially orienting the platelet-shaped magnetic or magnetizable pigment particles of said coating layer (x20).
A large variety of optical effect layers (OELs) for décorative and security applications may be produced with the process described herein. Magnetic-field-generating devices known in the art that allow the mono-axial orientation the platelet-shaped magnetic or magnetizable pigment particles may be used as first magnetic-field-generating devices (x30) including for example dipole magnets, quadrupolar magnets and combinations thereof. The substrate (x10) carrying the coating layer (x20) described herein concomitantly move with the first magnetic-field-generating device (x30) being mounted on the transferring device (TD) described herein, preferably on the rotating magnetic cylinder (RMC) described herein, in the vicinity of the static second magnetic-field-generating device (x40) and thus through the magnetic field of said second magnetic-field-generating device (x40), wherein said first magnetic-field-generating devices (x30) is not a spinning magnet by itself. Typical examples of suitable first magnetic-field-generating devices (x30) include the devices described herein.
OEL known as flip-flop effects (also referred in the art as switching effect) may be produced. Flipflop effects include a first printed portion and a second printed portion separated by a transition, wherein pigment particles are aligned parallel to a first plane in the first portion and flakes in the second portion are aligned parallel to a second plane. Methods and magnets for producing flip-flop effects are disclosed for example in US 2005/0106367 and EP 1 819 525 B1.
Optical effects known as rolling-bar effects as disclosed in US 2005/0106367 may also be produced. A “rolling bar” effect is based on pigment particles orientation imitating a curved surface across the coating. The observer sees a specular reflection zone which moves away or towards the observer as the image is tilted. The pigment particles are aligned in a curving fashion, either following a convex curvature (also referred in the art as négative curved orientation) or a concave curvature (also referred in the art as positive curved orientation). Methods and magnets for producing rollingbar effects are disclosed for example in EP 2 263 806 A1, EP 1 674 282 B1, EP 2 263 807 A1, WO 2004/007095 A2, WO 2012/104098 A1, and WO 2014/198905 A2.
Optical effects known as Venetian-blind effects may also be produced. Venetian-blind effects include pigment particles being oriented such that, along a spécifie direction of observation, they give visibility to an underlying substrate surface, such that indicia or other features présent on or in the substrate surface become apparent to the observer while they impede the visibility along another direction of observation. Methods for producing Venetian-blind effects are disclosed for example in US 8,025,952 and EP 1 819 525 B1.
Optical effects known as moving-ring effects may also be produced. Moving-ring effects consists of optically illusive images of objects such as funnels, cônes, bowls, circles, ellipses, and hémisphères that appear to move in any x-y direction depending upon the angle of tilt of said optical effect layer. Methods and magnets for producing moving-ring effects are disclosed for example in EP 1 710 756 A1, US 8,343,615, EP 2 306 222 A1, EP 2 325 677 A2, WO 2011/092502 A2 and US 2013/084411. Optical effects providing an optical impression of a pattern of moving bright and dark areas upon tilting said effect may also be produced. A method and magnets for producing these optical effects are disclosed for example in WO 2013/167425 A1.
Optical effects providing an optical impression of a loop-shaped body having a size that varies upon tilting said effect may also be produced. Methods and magnets for producing these optical effects are disclosed for example in the co-pending Applications EP 15189955.6, EP15193837.0 and
EP16157815.8.
Optical effects providing an optical impression of one or more loop-shaped bodies having a shape that varies upon tilting the optical effect layer may also be produced. A method and magnets for producing these optical effects are disclosed for example in the co-pending Application
EP16190044.4.
The first magnetic-field-generating device (x30) described herein may comprise a magnetic plate carrying one or more reliefs, engravings or cut-outs. WO 2005/002866 A1 and WO 2008/046702 A1 are examples for such engraved magnetic plates.
Contrary to a mono-axial orientation wherein the platelet-shaped magnetic or magnetizable pigment particles are orientated in such a way that only their main axis is constrained by the magnetic field vector component, carrying out a bi-axial orientation means that the platelet-shaped magnetic or magnetizable pigment particles are made to orient in such a way that both their two main axes X and Y are constrained. Such biaxial orientation is achieved, according to the invention, by exposing/subjecting and moving the substrate (x10) carrying the coating layer (x20) with the first magnetic-field-generating device (x30) described herein to and in the vicinity of the static second magnetic-field generating device (x40) (i.e. through the magnetic field ofthe static second magneticfield generating device (x40)). Accordingly, said second magnetic-field generating device (x40) must be configured in such a way that, along the path of motion followed by individual platelet-shaped magnetic or magnetizable pigment particles of the coating layer, the second magnetic field vector component change at least in direction or change in direction and intensity in the reference frame of the coating layer (x20), preferably within a plane which is fixed in the reference frame of the coating layer (x20). Bi-axial orientation aligns the planes of the platelet-shaped magnetic or magnetizable pigment particles so that said planes are oriented to be locally substantially parallel to each other.
Bi-axial orientation of the platelet-shaped magnetic or magnetizable pigment particles may be carried out by concomitantly moving the substrate (x10) carrying the coating layer (x20) with the first magnetic-field-generating device (x30) mounted on the transferring device (TD) described herein, preferably on the rotating magnetic cylinder (RMC) described herein, at an appropriate speed in the vicinity of a static second magnetic-field-generating device (x40) such as those described in EP 2 157 141 A1. Such devices provide a magnetic field that changes its direction while the platelet-shaped magnetic or magnetizable pigment particles move in the vicinity of said devices, forcing the platelet-shaped magnetic or magnetizable pigment particles to rapidly oscillate until both main axes, X-axis and Y-axis, stabilize, i.e. the platelet-shaped magnetic or magnetizable pigment particles oscillate until they reach a stable sheet-like formation with their respective X and Y axes planarized in said two dimensions. As shown in Figure 5 of EP 2 157 141, the magneticfield-generating device described herein comprises a linear arrangement of at least three magnets that are positioned in a staggered fashion or in zigzag formation, each of said three magnets having its magnetic axis substantially perpendicular to the substrate (x10) surface and said at least three magnets at the same side of a feedpath hâve the same at the same side of a feedpath hâve the same polarity, which is opposed to the polarity of the magnet(s) on the opposing side of the feedpath in a staggered fashion (as shown in the Fig. 5, said at least three magnets at the same side of a feedpath hâve the same polarity being on opposite sides of a feedpath where magnets at the same side of the feedpath hâve the same polarity, which is opposed to the polarity of the magnet(s) on the opposing side of the feedpath in a staggered fashion). The arrangement of the at least three magnets provides a predetermined change of the field direction as platelet-shaped magnetic or magnetizable pigment particles in a coating composition move past the magnets (direction of movement: arrow). According to one embodiment, the second magnetic-field-generating device (x40) comprises a) a first magnet and a third magnet on a first side of a feedpath and b) a second magnet between the first and third magnets on a second opposite side of the feedpath, wherein the first and third magnets hâve a same polarity, wherein the second magnet has a complementary polarity to the first and third magnets and wherein each of said three magnets has its magnetic axis substantially perpendicular to the substrate (x10) surface. According to another embodiment, the second magnetic-field-generating device (x40) further comprises a fourth magnet on the same side of the feedpath as the second magnet, having the polarity of the second magnet and complementary to the polarity of the third magnet, wherein the second magnet has a complementary polarity to the first and third magnets and wherein each of said four magnets has its magnetic axis substantially perpendicular to the substrate (x10) surface. As described in EP 2 157 141 A1, the magnetic-fieldgenerating device can be either underneath the layer comprising the platelet-shaped magnetic or magnetizable pigment particles, or above and underneath.
Carrying out a bi-axial orientation of the platelet-shaped magnetic or magnetizable pigment particles may be carried out by moving the substrate (x10) carrying the coating layer (x20) with the first magnetic-field-generating device (x30) mounted on the transferring device (TD) described herein, preferably on the rotating magnetic cylinder (RMC) described herein, at an appropriate speed in the vicinity of a static second magnetic-field-generating (x40) device being a linear permanent magnet Halbach array or through an arrangement of two or more Halbach arrays disposed in an appropriate arrangement. Linear permanent Halbach arrays consist of assemblies comprising a plurality of magnets with different magnetization directions. Detailed description of Halbach permanent magnets was given by Z.Q. Zhu et D. Howe (Halbach permanent magnet machines and applications: a review, IEE. Proc. Electric Power Appl., 2001,148, p. 299-308). The magnetic field produced by such a linear permanent magnet Halbach array has the properties that it is concentrated on one side while being weakened almost to zéro on the other side. Typically, linear permanent magnet Halbach arrays comprise one or more non-magnetic blocks made for example of wood or plastic, in particular plastics known to exhibit good self-lubricating properties and wear résistance such as polyacetal (also called polyoxymethylene, POM) resins, and magnets made of high-coercivity magnetic materials such as Neodymium-lron-Boron (NdFeB).
Carrying out a bi-axial orientation of the platelet-shaped magnetic or magnetizable pigment particles may be carried out by moving the substrate (x10) carrying the coating layer (x20) with the first magnetic-field-generating device (x30) mounted on the transferring device (TD) described herein, preferably on the rotating magnetic cylinder (RMC) described herein, at an appropriate speed in the vicinity of a static second magnetic-field-generating device (x40) such as those described in EP 1 519 794 B1. Suitable devices include permanent magnets being disposed on each side of the substrate (x10) carrying the coating layer (x20), above it, such that the magnetic field lines are substantially parallel to the substrate (x10) surface. According to one embodiment, the second magnetic-field-generating device (x40) comprises one or more pairs of two bar dipole magnets, wherein each of said two bar dipole magnets has its magnetic axis substantially parallel to the substrate (x10) surface and wherein the two bar dipole magnets hâve an opposite magnetic direction. According to another embodiment and as depicted in Fig. 4A-B, the second magneticfield-generating device (x40) comprises one or more pairs of two bar dipole magnets (x41a, x41b), wherein each of said two bar dipole magnets has its magnetic axis substantially perpendicular to the substrate (x10) surface and wherein the two bar dipole magnets hâve an opposite magnetic direction. According to another embodiment, instead of comprising one or more pairs of two bar dipole magnets, wherein each of said two bar dipole magnets has its magnetic axis substantially perpendicular to the substrate (x10) surface and wherein the two bar dipole magnets hâve an opposite magnetic direction, the second magnetic-field-generating device (x40) comprises a Ushaped magnet (also referred in the art as horseshoe magnet) having both a North and a South pôle located in the same plane at the open end of the magnet. The U-shaped magnet may be a single piece or may be built up from two separate pièces, wherein said two separate pièces may be in direct contact or may be spaced apart and connected together with a non-magnetic base.
The second magnetic-field-generating device (x40) may be comprised in one or more holders (x42). The one or more holders (x42) described herein are preferably made from the one or more nonmagnetic materials described herein for the one or more holders, the one or more plates or the one or more spacers (x31) described herein.
As described hereabove, the so-oriented platelet-shaped magnetic or magnetizable pigment particles are fixed/frozen in their orientation and position (i.e. after hardening) so as to form an optical effect layer (OEL). As shown in Fig. 1A, the hardening step described herein (step c)) is preferably carried out with a hardening unit (x50) while the substrate (x10) carrying the coating layer (x20) described herein is still on top of the first magnetic-field-generating device (x30) and while the substrate (x10) carrying the coating layer (x20) described herein is not moving in the vicinity of the static second magnetic-field-generating device (x40) any more, i.e. the hardening step described herein is carried out partially simultaneously with the step b), when the résultant magnetic field (H3) formed by the first and second magnetic field vector components (i.e. resulting from the vector addition of H1 and H2) described herein is greater than zéro, preferably greater than 50 mT.
Fig. 4A-C schematically depict an embodiment of a process for the orientation of platelet-shaped magnetic or magnetizable pigment particles comprised in a coating layer (x20) on a substrate (x10) using a transferring device (TD) being a linear magnetic transferring device (LMTD) according to the présent invention. Instead of mounting the first magnetic-field-generating device (x30) to a rotating magnetic orienting cylinder (RMC), said first magnetic-field-generating device (x30) is movable (see grey arrow) for example with the help of a rail (x33) in the vicinity ofthe static second magnetic field generating device (x40). As shown in Fig. 4A-C, the process described herein uses a movable first magnetic field generating device (430) and a static second magnetic field generating device (440) such as described herein.
In an embodiment shown in Fig. 4A-C, the first magnetic field generating device (430) consists of a bar dipole magnet having its South-North magnetic axis substantially parallel to the substrate (410) surface, having its North pôle pointing towards the second magnetic field generating device (440) and being disposed in a non-magnetic holder (431). The non-magnetic holder (431) comprising the first magnetic field generating device (430) is arranged on top of a supporting block (432) and a rail (433) so as to be moveable.
In an embodiment shown in Fig. 4A-C, the second magnetic field generating device (440) consists of two bar dipole magnets (441a and 441b), wherein said two bar dipole magnets (441a and 441b) are independently inserted in non-magnetic holders (442a and 442b) fixed to a non-magnetic frame (443), wherein said two bar dipole magnets (441a and 441b) hâve their South-North magnetic field direction opposite to each other (one bar dipole magnet (441a) hâve its South pôle facing the substrate (410) surface and the other (441b) having its North pôle facing the substrate (410) surface), wherein each of said two bar dipole magnets (441a and 441b) has its South-North magnetic axis perpendicular to the substrate (410) surface (i.e. its South-North magnetic axis substantially perpendicular to South-North magnetic axis of the first magnetic field generating device (430) surface) and wherein said two bar dipole magnets (441a and 441b) are spaced apart by a distance A1.
Preferably, the surface ofthe substrate (410) carrying the coating layer (420) is flush with the bottom surface of the two bar dipole magnets (441a and 441b). Preferably, the center of the coating layer (420) is placed on the center of the first magnetic field generating device (430) and is placed at an equal distance between the two bar dipole magnets (441a and 441b) of the second magnetic field generating device (440), i.e. at a distance A1 from each bar dipole magnets (441a and 441b).
As shown in Fig. 4A, the hardening step described herein is preferably carried out while the substrate (410) carrying the coating composition (420) herein is still on top of the first magneticfield-generating device (430) and while the substrate (410) and the first magnetic-field-generating device (430) hâve moved at a distance (X) away from the static second magnetic field generating device (440) in the direction of the movement.
The présent invention further provides printing apparatuses and the uses thereof for producing the optical effect layers (OELs) described herein. The printing apparatuses described herein comprises the transferring device (TD) described herein, preferably the rotating magnetic cylinder (RMC) described herein, and at least one ofthe second magnetic-field-generating devices (x40) described herein, wherein the transferring device (TD) described herein, preferably the rotating magnetic cylinder (RMC) described herein, comprises at least one of the first magnetic-field-generating devices (x30) described herein, wherein said at least one of the first magnetic-field-generating devices (x30) described herein is mounted on said transferring device (TD) described herein.
Preferably, the printing apparatuses described herein comprises the rotating magnetic cylinder (RMC) described herein and at least one of the second magnetic-field-generating devices (x40) described herein, wherein the rotating magnetic cylinder (RMC) described herein comprises at least one of the first magnetic-field-generating devices (x30) described herein, wherein said at least one of the first magnetic-field-generating devices (x30) described herein is preferably mounted on circumferential grooves or transverse grooves of the rotating magnetic cylinder (RMC). In an embodiment, the rotating magnetic cylinder (RMC) is part of a rotary, sheet-fed orweb-fed industrial printing press that opérâtes at high printing speed in a continuous way.
The transferring device (TD), preferably the rotating magnetic cylinder (RMC), comprising at least one of the first magnetic-field-generating devices (x30) mounted thereon as well as the at least one ofthe second magnetic-field-generating devices (x40) described herein are meantto be used in, or in conjunction with, or being part of a printing or coating equipment. In an embodiment, the transferring device (TD) is a rotating magnetic cylinder (RMC) such as those described herein, wherein said rotating magnetic cylinder (RMC) is preferably part of a rotary, sheet-fed or web-fed industrial printing press that opérâtes at high printing speed in a continuous way.
The printing apparatuses comprising the transferring device (TD) described herein, preferably the rotating magnetic cylinder (RMC) described herein, comprising at least one of the first magneticfield-generating devices (x30) described herein as well as the at least one of the second magneticfield-generating devices (x40) described herein may include a substrate feeder for feeding a substrate such as those described herein having thereon a layer of platelet-shaped magnetic or magnetizable pigment particles described herein, so that the first magnetic-field-generating device (x30) and the second first magnetic-field-generating device (x40) generate a résultant magnetic field that acts on the pigment particles to orient them to form an optical effect layer (OEL). In an embodiment ofthe printing apparatuses comprising the transferring device (TD) described herein, preferably the rotating magnetic cylinder (RMC) described herein, the substrate is fed by the substrate feeder under the form of sheets or a web.
The printing apparatuses comprising the transferring device (TD) described herein, preferably the rotating magnetic cylinder (RMC) described herein, comprising at least one of the first magneticfield-generating devices (x30) described herein as well as the at least one ofthe second magneticfield-generating devices (x40) described herein may include a substrate-guiding System. As used herein, a substrate-guiding System refers to a set-up that holds the substrate (x10) carrying the coating layer (x10) in close contact with the transferring device (TD) described herein, preferably the rotating magnetic cylinder (RMC) described herein, and the first magnetic-field-generating devices (x30). The substrate-guiding System may be a gripper and/or a vacuum System. Particularly, the gripper may serve the purpose of holding the leading edge ofthe substrate (x10) and allowing the (x10) to be transferred from one partofthe printing machineto the next, and the vacuum System may serve to pull the surface of the (x10) against the surface of the transferring device (TD) described herein, preferably the rotating magnetic cylinder (RMC) described herein, and the first magnetic-field-generating devices (x30) and maintain it firmly aligned therewith. The substrate26 guiding system may comprise, in addition to or instead of the gripper and/or the vacuum system other pièces of substrate-guiding equipment including without limitation a roller or a set of rollers, a brush or a set of brushes, a belt and/or a set of belts, a blade or a set of blades, or a spring or a set of springs.
The printing apparatuses comprising the transferring device (TD) described herein, preferably the rotating magnetic cylinder (RMC) described herein, comprising at least one of the first magneticfield-generating devices (x30) described herein as well as the at least one ofthe second magneticfield-generating devices (x40) described herein may include a coating or printing unit for applying the coating composition comprising the platelet-shaped magnetic or magnetizable pigment particles described herein on the substrate (x10) described herein so as to form the coating layer (x20) described herein.
The printing apparatuses comprising the transferring device (TD) described herein, preferably the rotating magnetic cylinder (RMC) described herein, comprising at least one of the first magneticfield-generating devices (x30) described herein as well as the at least one of the second magneticfield-generating devices (x40) described herein may include a hardening unit (x50), preferably a curing unit, for at least partially hardening the coating layer (x20) comprising platelet-shaped magnetic or magnetizable pigment particles that hâve been magnetically oriented by the résultant magnetic field formed by the first and second magnetic field vector components of the first and second magnetic-field-generating devices (x30 and x40) described herein, thereby fixing the orientation and position of the platelet-shaped magnetic or magnetizable pigment particles to produce an optical effect layer (OEL).
The présent invention provides the processes described herein and the printing apparatuses described herein to produce an optical effect layer (OEL) on the substrate (x10) described herein. The substrate (x10) described herein is preferably selected from the group consisting of papers or other fibrous materials (including woven and non-woven fibrous materials), such as cellulose, papercontaining materials, glasses, metals, ceramics, plastics and polymers, metallized plastics or polymers, composite materials and mixtures or combinations of two or more thereof. Typical paper, paper-like or other fibrous materials are made from a variety of fibers including without limitation abaca, cotton, linen, wood pulp, and blends thereof. As is well known to those skilled in the art, cotton and cotton/linen blends are preferred for banknotes, while wood pulp is commonly used in non-banknote security documents. Typical examples of plastics and polymers include polyolefins such as polyethylene (PE) and polypropylene (PP) including biaxially oriented polypropylene (BOPP), polyamides, polyesters such as poly(ethylene terephthalate) (PET), poly(1,4-butylene terephthalate) (PBT), poly(ethylene 2,6-naphthoate) (PEN) and polyvinylchlorides (PVC). Spunbond olefin fibers such as those sold under the trademark Tyvek® may also be used as substrate. Typical examples of metalized plastics or polymers include the plastic or polymer materials described hereabove having a métal disposed continuously or discontinuously on their surface. Typical example of metals include without limitation aluminum (Al), chromium (Cr), copper (Cu), gold (Au), silver (Ag), alloys thereof and combinations of two or more of the aforementioned metals. The metallization of the plastic or polymer materials described hereabove may be done by an electrodeposition process, a high-vacuum coating process or by a sputtering process. Typical examples of composite materials include without limitation multilayer structures or laminates of paper and at least one plastic or polymer material such as those described hereabove as well as plastic and/or polymerfibers incorporated in a paper-like orfibrous material such as those described hereabove. Of course, the substrate can comprise further additives that are known to the skilled person, such as fillers, sizing agents, whiteners, processing aids, reinforcing or wet strengthening agents, etc. When the OELs produced according to the présent invention are used for décorative or cosmetic purposes including for example fingernail lacquers, said OEL may be produced on other type of substrates including nails, artificial nails or other parts of an animal or human being.
Should the OEL produced according to the présent invention be on a security document, and with the aim of further increasing the security level and the résistance against counterfeiting and illégal reproduction of said security document, the substrate may comprise printed, coated, or lasermarked or laser-perforated indicia, watermarks, security threads, fibers, planchettes, luminescent compounds, Windows, foils, decals and combinations of two or more thereof. With the same aim of further increasing the security level and the résistance against counterfeiting and illégal reproduction of security documents, the substrate may comprise one or more marker substances or taggants and/or machine readable substances (e.g. luminescent substances, UV/visible/IR absorbing substances, magnetic substances and combinations thereof).
If desired, a primer layer may be applied to the substrate prior to the step a). This may enhance the quality of the optical effect layer (OEL) described herein or promote adhesion. Examples of such primer layers may be found in WO 2010/058026 A2.
With the aim of increasing the durability through soiling or Chemical résistance and cleanliness and thus the circulation lifetime of an article, a security document or a décorative element or object comprising the optical effect layer (OEL) obtained by the process described herein, or with the aim of modifying their aesthetical appearance (e.g. optical gloss), one or more protective layers may be applied on top ofthe optical effect layer (OEL). When présent, the one or more protective layers are typically made of protective varnishes. Protective varnishes may be radiation curable compositions, thermal drying compositions or any combination thereof. Preferably, the one or more protective layers are radiation curable compositions, more préférable UV-Vis curable compositions. The protective layers are typically applied after the formation of the optical effect layer (OEL).
The présent invention further provides optical effect layers (OEL) produced by the process described herein and/or by using the printing apparatus described herein.
The optical effect layer (OEL) described herein may be provided directly on a substrate on which it shall remain permanently (such as for banknote applications). Alternatively, an optical effect layer (OEL) may also be provided on a temporary substrate for production purposes, from which the OEL is subsequently removed. This may for example facilitate the production of the optical effect layer (OEL), particularly while the binder material is still in its fluid state. Thereafter, after hardening the coating composition for the production of the optical effect layer (OEL), the temporary substrate may be removed from the OEL.
Alternatively, in another embodiment an adhesive layer may be présent on the optical effect layer (OEL) or may be présent on the substrate comprising OEL, said adhesive layer being on the side of the substrate opposite to the side where the OEL is provided or on the same side as the OEL and on top of the OEL. Therefore an adhesive layer may be applied to the optical effect layer (OEL) or to the substrate, said adhesive layer being applied after thé curing step has been completed. Such an article may be attached to ail kinds of documents or other articles or items without printing or other processes involving machinery and rather high effort. Alternatively, the substrate described herein comprising the optical effect layer (OEL) described herein may be in the form of a transfer foil, which can be applied to a document orto an article in a separate transfer step. For this purpose, the substrate is provided with a release coating, on which the optical effect layer (OEL) are produced as described herein. One or more adhesive layers may be applied over the so produced optical effect layer (OEL).
Also described herein are substrates comprising more than one, i.e. two, three, four, etc. optical effect layers (OEL) obtained by the process described herein.
Also described herein are articles, in particular security documents, décorative éléments or objects, comprising the optical effect layer (OEL) produced according to the présent invention. The articles, in particular security documents, décorative éléments or objects, may comprise more than one (for example two, three, etc.) OELs produced according to the présent invention.
As mentioned hereabove, the optical effect layer (OEL) produced according to the présent invention may be used for décorative purposes as well as for protecting and authenticating a security document.
Typical examples of décorative éléments or objects include without limitation luxury goods, cosmetic packaging, automotive parts, electronic/electrical appliances, fumiture and fingernail articles.
Security documents include without limitation value documents and value commercial goods. Typical example of value documents include without limitation banknotes, deeds, tickets, checks, vouchers, fiscal stamps and tax labels, agreements and the like, identity documents such as passports, identity cards, visas, driving licenses, bank cards, crédit cards, transactions cards, access documents or cards, entrance tickets, public transportation tickets, academie diploma or titles and the like, preferably banknotes, identity documents, right-conferring documents, driving licenses and crédit cards. The term “value commercial good” refers to packaging materials, in particular for cosmetic articles, nutraceutical articles, pharmaceutical articles, alcohols, tobacco articles, beverages or foodstuffs, elëctrical/electronic articles, fabrics or jewelry, i.e. articles that shall be protected against counterfeiting and/or illégal reproduction in order to warrant the content of the packaging like for instance genuine drugs. Examples of these packaging materials include without limitation labels, such as authentication brand labels, tamper evidence labels and seals. It is pointed out that the disclosed substrates, value documents and value commercial goods are given exciusively for exemplifying purposes, without restricting the scope of the invention.
Alternatively, the optical effect layer (OEL) may be produced onto an auxiliary substrate such as for example a security thread, security stripe, a foil, a decal, a window or a label and consequently transferred to a security document in a separate step.
The skilled person can envisage several modifications to the spécifie embodiments described above without departing from the spirit of the présent invention. Such modifications are encompasses by the présent invention.
Further, ali documents referred tothroughoutthis spécification are hereby incorporated by reference in their entirety as set forth in full herein.
EXAMPLES
The Examples hâve been carried out by using the UV-curable screen printing ink of the formula given in Table 1 and the first and second magnetic-field-generating devices described herebelow.
Table 1
| Epoxyacrylate oligomer | 28 wt-% |
| Trimethylolpropane triacrylate monomer | 19.5 wt-% |
| Tripropyleneglycol diacrylate monomer | 20 wt-% |
| Genorad 16 (Rahn) | 1 wt-% |
| Aerosil 200 (Evonik) | 1 wt-% |
| Speedcure TPO-L (Lambson) | 2 wt-% |
| Irgacure® 500 (BASF) | 6 wt-% |
| Genocure® EPD (Rahn) | 2 wt-% |
| BYK® 371 (BYK) | 2 wt-% |
| Tego Foamex N (Evonik) | 2 wt-% |
| 7-layer optically variable magnetic pigment particles (*) | 16.5 wt-% |
(*) 7-layer gold-to-green platelet-shaped optically variable magnetic pigment particles having a flake shape of diameter dso about 9.3pm and thickness about 1pm, obtained from JDS-Uniphase, Santa Rosa, CA.
First magnetic-field-generating device (Fig. 4A-C, not at scale)
A bar dipole magnet (430) made of NdFeB N40 was used as the first magnetic field generating device. The bar dipole magnet (430) had the following dimensions: 30 mm (L1) x 18 mm (L2) x 6 mm (L3). As shown in Fig. 4B-C, the bar dipole magnet (430) was embedded in a non-magnetic holder (431) made of high density polyethylene (HDPE) and having the following dimensions: 40 mm (L7) x 40 mm (L8) x 25 mm (L9). The top surface ofthe bar dipole magnet (430) was placed at a distance (A2) of about 15 mm from the top surface of the non-magnetic holder (431).
As shown in Fig. 4B-C, the bar dipole magnet (430) embedded in the non-magnetic holder (431) was movable in the vicinity of the static second magnetic field generating device (440) (i.e. through the magnetic field of the second magnetic field generating device (440)) with the help of a supporting block (432) and a rail (433), wherein said rail (433) was fixed to a frame (443).
The rail (433) (from ThorLabs) was made of anodized aluminum and had the following dimensions:
448 mm (L13) x40 mm (L14) x 10 mm (L15).
The supporting block (432) comprised a first piece (432a), a second piece (432b). The first piece (432a) was made of anodized aluminum (Aluminum Breadoard from ThorLabs) and had the following dimensions: 112 mm (L16) x 65 mm (L17) x 13 mm (L18) and was glued on top of the second piece (432b). The second piece (432b) was made of high density polyethylene (HDPE), had the following dimensions: 112 mm (L16) x 65 mm (L17) x 37 mm (L19) and comprised a recess suitable to dispose the second piece (432b) on the rail (433) and having the following dimensions: 65 mm (L17) x 40 mm (L14) x 5 mm (L20).
The supporting block (432) made of the two pièces (432a-b) was disposed on the rail (433) so as to be moveable by gliding on said rail (433) along its length (see Fig. 4A).
Second magnetic-field-generating device (Fig. 4A-4B, not at scale)
A pair of two bardipole magnets (441a and 441b) was used as the second magnetic field generating device (440). Each of the two bar dipole magnets (441a and 441b) had the following dimensions: 48 mm (L4) x 24 mm (L5) x 10 mm (L6) and was made of NdFeB N40. The magnetic axis of each of the two bar dipole magnets (441a and 441b) was substantially parallel to the length (L4) of said magnets (i.e. substantially perpendicular to the substrate (410) surface), the magnetic direction of the first of said two bar dipole magnets (441a) being opposite to the magnetic direction of the second of said two bar dipole magnets (441 b). The two dipole bar magnets (441 a and 441 b) were located at a distance (A1 = 48 mm) from each other and were independently embedded in a pair of nonmagnetic holder (442a and 442b) made of polyoxymethylene (POM).
As shown in Fig. 4B, the pair of non-magnetic holder comprised two blocks (442a and 442b), each one having the following dimensions: 52 mm (L10) x 30 mm (L11) x 12 mm (L12) and each one comprising a recess for independently inserting the two bar dipole magnets (441a and 441b). Each of the two bar dipole magnets (441a and 441b) was located at a distance (A3) of about 1 mm from the surface of its respective non-magnetic holder (442a and 442b) facing the other bar dipole magnet and at a distance (A4) of about 2 mm from the lowest surface of its respective non-magnetic holder (442a and 442b).
As shown in Fig. 4B, the two non-magnetic holders (442a and 442 b) were connected together with a frame (443) made of anodized aluminum and comprising two frame breadboards (443a and 443c) (Aluminum Breadboard from Thorlabs Inc.) and a frame column (443b) made of anodized aluminum (Large Right Angle Bracket AP90/RL from Thorlabs Inc.).
The frame breadboard (443a) had the following dimensions: 450 mm (L21) x 300 mm (L22) x 13 mm (L23). The frame column (443b) had the following dimensions: 176 mm (L24) x 125 mm (L26) x 30 mm (L25). The frame breadboard (443c) had the following dimensions: 385 mm (L28) x 100 mm (L27)x13mm (L23).
The frame (443) comprised three right angle plates (443d) having the following dimensions: 64 mm (L29) x 8 mm (L30) x 75 mm (L31) x 8 mm (L32) x 8 mm (L33) x 70 mm (L34) x 34 mm (L35).
Sample 1 (Fig. 4)
A 25 mm x 25 mm square sample was printed onto black paper substrate (Gascogne Laminates Mcote 120) (410) with the UV-curable screen printing ink of Table 1 with a laboratory screen printing device using a T90 screen so as to form a coating layer (420) having a thickness of about 20 pm. While the coating layer (420) was still in a wet and not yet hardened state, the substrate (410) was placed on top of the first magnetic field generating device (430), in particular on top of the nonmagnetic holder (431), with the center of said coating layer (420) being placed on the center of the first magnetic field generating device (430). The substrate (410) carrying the coating layer (420) was placed at a distance (A2) of about 15 mm from the top surface of said first magnetic field generating device (430), i.e. the substrate (410) was placed in direct contact with the holder (431), so as to form an assembly. The magnetic axis of the bar dipole magnet of said first magnetic field generating device (430) was substantially parallel to the substrate (410) surface with the North pôle pointing in a direction substantially perpendicular to the two opposing magnetic axes of the bar magnets (441a, 441b) ofthe second magneticfield generating device (440).
As shown in Fig. 4A and with the help ofthe supporting block (432) and the track (433), the substrate (410) carrying the coating layer (420) and the non-magnetic holder (431) comprising the first magnetic field generating device (430) were concomitantly moved back and forth eight times at a linear speed of about 10 cm/s in the vicinity of the second magnetic field generating device (440). The substrate (410) carrying the coating layer (420) and the holder (431) comprising the first magnetic field generating device (430) were concomitantly moved in the vicinity of the second magnetic field generating device (440), the center ofthe first magnetic field generating device (430) (also corresponding to the center of the coating layer (420)) being placed at a distance (½ A1) of about 24 mm from each bar dipole magnets (441a and 441b) and the surface ofthe substrate (410) being flush with the bottom surface ofthe dipole bar magnets (441a and 441b). Each ofthe two bar dipole magnets (441a and 44ab) of said second magnetic field generating device (440) had a magnetic axis perpendicular to the substrate (410) surface and the two bar dipole magnets (441a and 441b) had an opposite magnetic direction, i.e. one of said two bar dipole magnets (441a) had its South pôle pointing to the substrate (410) surface and the other (441b) had its North pôle pointing to the substrate (410) surface.
While the substrate (410) carrying the coating layer (420) was still in contact with the non-magnetic holder (431) comprising the first magnetic field generating device (430) and while the substrate (410) carrying the coating layer (420) and the non-magnetic holder (431) comprising the first magnetic field generating device (430) were concomitantly moving at a distance (X) of about 50 mm away from the second magnetic field generating device (440) in the direction of the movement (shown as a grey arrow in Fig. 4A), the coating layer (420) was hardened upon exposure during about 0.5 second to a UV-LED-lamp (450) from Phoseon (Type FireFlex 50 x 75 mm, 395 nm,
8W/cm2) positioned at a distance of about 30 mm from the top surface ofthe substrate (410) carrying the coating layer (420) so as to form an OEL.
Comparative sample 1
The comparative sample was prepared according to a general procedure according to the prior art WO 2015/086257 A1, comprising the following steps:
step i): a 25 mm x 25 mm square sample was printed onto black paper substrate (Gascogne Laminates M-cote 120) with the UV-curable screen printing ink of Table 1 with a laboratory screen printing device using a T90 screen so as to form a coating layer having a thickness of about 20 pm; step ii): while the coating layer was still in a wet and not yet hardened state, the substrate was placed on top of the non-magnetic holder described for sample 1 but lacking the first magnetic field generating device, with the center of said coating layer being placed on the center of the nonmagnetic holder. With the help the supporting block and the track described hereabove the coating layer was exposed to the magnetic field of the second magnetic field generating device described hereabove and moved in the vicinity of the second magnetic field generating device described for sample 1 back and forth eight times at a linear speed of about 10 cm/s, the center of the nonmagnetic holder being placed at a distance of about 24 mm from each bar dipole magnets and the lowest surface ofthe substrate being flush with the lowest surface ofthe dipole bar magnets; and step iii): the substrate carrying the coating layer was removed from the magnetic field of the second magnetic field generating device and was exposed to the magnetic field of the first magnetic field generating device described hereabove. The substrate carrying the coating layer was placed at a distance of about 15 mm from the top surface of said first magnetic field generating device, i.e. the substrate was placed in direct contact with the non-magnetic holder.
step iv): partially simultaneously with step iii), the coating layer was hardened upon exposure during about 0.5 second to a UV-LED-lamp from Phoseon (Type FireFlex 50 x 75 mm, 395 nm, 8W/cm2) positioned at a distance of about 30 mm from the top surface of the substrate carrying the coating layer so as to form an OEL.
Brightness measurement
The brightness ofthe OEL of Sample 1 and of Comparative sample 1 was independently compared to an OEL prepared by only using the first magnetic field generating device (430) described above and according to the following process:
i) applying the coating layer of Table 1 (420) (25 x 25 mm) on a substrate (410) (black paper substrate from Gascogne Laminates M-cote 120) with a laboratory screen printing device using a T90 screen so as to form a coating layer having a thickness of about 20 pm;
ii) exposing the substrate (420) to the first magnetic field generating device (430) by placing the substrate (410) on top of and in direct contact with the non-magnetic holder (431);
iii) applying a photomask (a 30 x 30 mm aluminum plate (100% opacity) comprising a 12.5 x 25 mm void) to hide about half of the surface of the not yet hardened coating layer (420), iv) partially simultaneously with the orientation step, i.e. while the substrate (410) carrying the coating layer (420) was still exposed to the magnetic field of the first magnetic-field generating device (430), exposing said half-masked coating layer (420) during 0.5 sec to the UV radiation of a UV-LED-lamp from Phoseon (Type FireFlex 50 x 75 mm, 395 nm, 8 W/cm2) at a distance of about 30 mm from the top surface ofthe substrate (410), so as to fix/freeze the orientation ofthe optically variable magnetic pigment particles in the unmasked area (Fig 5A and Fig. 5B, area A) of the coating layer (410),
v) removing the photomask, and vi) applying the procedure used to préparé Sample 1 and Comparative sample 1 to the substrate (420) so as to orient the platelet-shaped magnetic optically variable pigment particles in the not yet hardened area corresponding to the initially masked area (Fig 5A and Fig. 5B, area B).
The resulting OELs are shown in Fig. 5A (Sample 1) and Fig. 5B (Comparative sample 1).
The brightness différence between the area A and the area B was quantified according to the following method:
a) taking a picture of the OEL using the following set-up:
i. Lighting: Reflecta LED Videolight RPL49, positioned at a 12.5° angle to the OEL and at a distance of 45cm ii. Caméra: Nikon D800, ISO800, aperture F40, speed 1/125s, color température 5565K, objective: AF-S Micro Nikkor 105mm 2.8G ED, manual focus at45cm iii. In-camera conversion of each picture to color 8-bit TIFF format iii i.Analysis software: Adobe Photoshop CS4
v. Lightness scale (V): 0 (full black) to 255 (full white)
b) opening each picture in Photoshop and transforming it in a grey scale 8-bit image by applying the Image/AdjustmenVBIack&White operation. Two Virtual dotted lines comprising 6 segments were drawn along the brightest area of each picture, one on the initially masked area (Fig. 5A and Fig. 5B , area A) ofthe OEL and the other on the initially unmasked area of the OEL (Fig. 5A and Fig. 5B , area B). Inside each segment, the lightness V was determined and two average values, Va and Vb were calculated. Va corresponded to the maximal brightness ofthe area B ofthe OEL that, and Vb corresponded to the area A of the OEL. The orientation method described herein therefore resulted in a brightness increase calculated in % as AV = [(Va - Vb) / Vb] * 100.
The brightness increase AV for Sample 1 (Fig. 5A) was 64%, whereas AV for Comparative sample 1 (Fig. 5B) was 40%.
Claims (14)
1. A process for producing an optical effect layer (OEL) on a substrate (x10), said process comprising the steps of:
a) applying onto a substrate (x10) surface a coating composition comprising plateletshaped magnetic or magnetizable pigment particles so as to form a coating layer (x20) on said substrate (x10), said coating composition being in a first state,
b) placing the substrate (x10) carrying the coating layer (x20) on a first magnetic-fieldgenerating device (x30) providing a first magnetic field vector component, said first magnetic-field-generating device (x30) being mounted on a transferring device (TD) thereby subjecting the platelet-shaped magnetic or magnétisable pigment particles to said first magnetic field vector component, concomitantly moving said substrate (x10) carrying the coating layer (x20) and said first magnetic-field-generating device (x30) in the vicinity of a static second magnetic-fieldgenerating device (x40), said second magnetic-field-generating device (x40) providing a second magnetic field vector component thereby subjecting the platelet-shaped magnetic or magnétisable pigment particles to a time-dependent résultant magnetic field formed by the first and second magnetic field vector components so as to bi-axially orient at least a part of the platelet-shaped magnetic or magnetizable pigment particles, and
c) hardening the coating composition to a second state so as to fix the platelet-shaped magnetic or magnetizable pigment particles in their adopted positions and orientations.
2. The process according to claim 1, wherein the transferring device (TD) is a rotating magnetic cylinder (RMC).
3. The process according to claim 1 or 2, wherein the step of applying the coating composition onto the substrate (x10) is carried out by printing process selected from the group consisting of intaglio printing, screen printing, rotogravure printing and flexography printing.
4. The process according to any preceding claims, wherein the coating composition is a UV-Vis curable composition and the hardening step is carried out by UV-Vis curing.
5. The process according to any preceding claim, wherein the step c) of hardening the coating composition is carried out partially simultaneously with the step b).
6. The process according to any preceding claim, wherein the first magnetic-field-generating device (x30) is selected from the group consisting of dipole magnets, quadrupolar magnets and combinations thereof.
7. The process according to any preceding claim, wherein the second magnetic-field-generating device (x40) comprises a) a linear arrangement of at least three magnets that are positioned in a staggered fashion, wherein each of said three magnets has its magnetic axis substantially perpendicular to the substrate (x10) surface, and wherein said at least three magnets at the same side of a feedpath hâve the same polarity, which is opposed to the polarity of the magnet(s) on the opposing side ofthefeedpath, b) a linearpermanent magnet Halbach array,
c) one or more pairs of two bar dipole magnets, wherein each of said two bar dipole magnets has its magnetic axis substantially parallel to the substrate (x10) surface and wherein the two bar dipole magnets hâve an opposite magnetic direction, d) one or more pairs of two bar dipole magnets (x41a, x41b), wherein each of said two bar dipole magnets has its magnetic axis substantially perpendicular to the substrate (x10) surface and wherein the two bar dipole magnets hâve an opposite magnetic direction or e) a U-shaped magnet.
8. The process according to any preceding claim, wherein the platelet-shaped magnetic or magnetizable pigment particles are platelet-shaped optically variable magnetic or magnetizable pigment particles selected from the group consisting of platelet-shaped magnetic thin-film interférence pigment particles, platelet-shaped magnetic cholesteric liquid crystal pigment particles, platelet-shaped interférence coated pigment particles comprising a magnetic material and mixtures of two or more thereof.
9. The process according to any preceding claim, wherein the substrate is selected from the group consisting of papers or other fibrous materials, paper-containing materials, glasses, metals, ceramics, plastics and polymers, metalized plastics or polymers, composite materials and mixtures or combinations thereof.
10. A printing apparatus comprising a transferring device (TD), preferably a rotating magnetic cylinder (RMC), and at least one of the second magnetic-field-generating devices (x40) recited in any one of claims 1 to 8, said transferring device (TD), preferably said rotating magnetic cylinder (RMC), comprising at least one of the first magnetic-field-generating devices (x30) mounted thereon and recited in any one of claims 1 to 9.
11. The printing apparatus of claim 10 further comprising a substrate-guiding system.
12. An optical effect layer (OEL) produced by the process recited in any one of claims 1 to 9 or produced by using the printing apparatus recited in claim 10 or 11.
13. A security document or a décorative element or object comprising one or more optical effect layer (OEL) recited in claim 12.
14. Method of manufacturing a security document or a décorative element or object, comprising:
a) providing a security document or a décorative element or object, and
b) providing an optical effect layer according to the process of one of claims 1 to 9 so that it is comprised in the security docuOm.ent or décorative element or object.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP18152081.8 | 2018-01-17 | ||
| EP18152082.6 | 2018-01-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| OA19872A true OA19872A (en) | 2021-06-23 |
Family
ID=
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA3088461C (en) | Processes for producing optical effects layers | |
| AU2017314105B2 (en) | Processes for producing effects layers | |
| EP3174733B1 (en) | Belt-driven processes for producing optical effect layers | |
| EA038007B1 (en) | Processes for producing optical effect layers | |
| OA19872A (en) | Processes for producing optical effects layers. | |
| OA19609A (en) | Processes for producing optical effects layers | |
| EA038016B1 (en) | Processes for producing optical effect layers |