Lamination of AOM

Abstract

A substrate coated with a markable ink formulation, comprising AOM. Further, the substrate is covered by a thermoplastic polymer layer, such that the ink formulation is situated between the substrate and the thermoplastic polymer layer and/or in the thermoplastic polymer layer.

Claims

1. A method for marking a coated substrate coated with an ink formulation having a salt of a transition metal oxyanion, the method comprising: irradiating parts of the coated substrate that are covered by a thermoplastic polymer layer where a marking is intended, in order to generate a marking, wherein the coated substrate is covered by a thermoplastic polymer layer comprising a polyolefin having a thickness from 10 to 60 m, by melt extrusion at a temperature ranging from 200 to 340 C., wherein the ink formulation is situated between the substrate and the thermoplastic polymer layer.

2. The method according to claim 1, wherein said ink formulation is coated in a defined pattern and at least parts of the defined pattern are irradiated in order to generate said marking.

3. The method according to claim 1, wherein substrate is irradiated with an irradiation source selected from a group consisting of a laser, a diode, a fiber coupled diode array system, and a diode array system.

4. The method according to claim 3, wherein the irradiation source has an operating wavelength in the range of 780 to 2500 nm.

5. The method according to claim 4, wherein the irradiation source is a Nd:YAG laser or a NIR fiber laser.

6. The method according to claim 1, wherein the thermoplastic polymer layer comprises a polyolefin.

7. The method according to claim 1, wherein coating said substrate is performed by flexographic printing.

8. The method according to claim 1, wherein said ink formulation further comprises a near infra-red absorber.

9. The method according to claim 1, wherein said substrate is comprised of one of paper, cardboard, corrugated paper board, paper board, plastic film, ridged plastic parts, textile, wood, metal, glass, or leather.

10. The method according to claim 1, wherein said ink formulation further comprises one of a binder, a light stabilizing agent, an ink flow/rheology modifier, a drying rate modifier, and/or an adhesion promoters.

11. The method according to claim 1, wherein said ink formulation is water-based.

12. The method according to claim 1, wherein said salt of a transition metal oxyanion is ammonium octamolybdate.

13. The method according to claim 1, wherein the coated substrate is covered by a thermoplastic polymer layer by melt extrusion at a temperature ranging from 280 to 330 C.

14. The method according to claim 1, wherein said ink formulation further comprises a near infrared absorber comprising indium tin oxide.

15. The method according to claim 14, wherein said indium tin oxide is reduced indium tin oxide.

16. A method of making a substrate configured to have a marking, the method comprising: coating the substrate with an ink formulation comprising a salt of a transition metal oxyanion to form a coated substrate; and covering the coated substrate with a thermoplastic polymer layer, having a thickness ranging from 10 to 60 m, by melt extrusion at a temperature ranging from 200 to 340 C., wherein the ink formulation is situated between the substrate and the thermoplastic polymer layer, wherein at least a portion of the coated substrate is capable of being irradiated to generate the marking.

17. The method according to claim 16, wherein the step of coating the substrate is performed by flexographic printing.

18. The method according to claim 16, wherein the thermoplastic polymer layer comprises a polyolefin.

19. The method of claim 18, wherein the polyolefin comprises polyethylene or polypropylene.

20. The method according to claim 16, wherein the melt extrusion is performed at a temperature ranging from 280 to 330 C.

21. The method according to claim 16, wherein said ink formulation further comprises a near infra-red absorber.

22. The method according to claim 16, wherein said ink formulation further comprises one of a binder, a light stabilizing agent, an ink flow/rheology modifier, a drying rate modifier, and/or an adhesion promoters.

23. The method according to claim 16, wherein said ink formulation is water-based.

24. The method according to claim 16, wherein said substrate is comprised of one of paper, cardboard, corrugated paper board, paper board, plastic film, ridged plastic parts, textile, wood, metal, glass, or leather.

25. The method according to claim 16, wherein said salt of a transition metal oxyanion is ammonium octamolybdate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1, schematically illustrates a roll fed filling machine.

(2) The following examples are mere examples and should by no mean be interpreted to limit the scope of the invention. Rather, the invention is limited only by the accompanying claims.

(3) Three marking components of different type, i.e. a TAG/Leuco dye (benzyl p-hydroxybenzoate/ETAC), charrables (fructose//sucrose), and an oxymetal salt (AOM) were chosen for assessing the printing properties of such marking components when overlaid by a polymer layer.

(4) Three ink formulations were thus prepared by premixing the ink components, including water, using a Silverson mixer. The pre-mixed ink was then milled using an Eiger-Torrance bead mill until a Hegman grind gauge particle size reading of less than 5 microns was obtained. The printing properties of the obtained formulations were evaluated. Details regarding the formulations and the experimental details are provided below. In preparing the ink formulations, the following components were used: r-ITO (90:10 In to Sn by weight) was used in the form of a nanopowderinfra red absorber. Joncryl LMV7085 (ex. BASF)styrene-acrylic resin solution binder. Dispex A40 (ex. BASF)Solution of an ammonium salt of an acrylic polymer in water-dispering agent. ETAC (ex. Yamada)halochromic leuco dye colour former. Benzyl p-hydroxybenzoate (ex. Sigma-Aldrich)thermal acid generator. Glascol LS2 (ex. BASF)aqueous acrylic binder. Dispelair CF49 (ex. Blackburn Chemicals)mineral oil based defoamer. DEG (ex. Sigma-Aldrich) diethylene glycol-drying retarder. Tyzor LA (ex. Dupont)Titanium lactate in an aqueous solution adhesion promoter. Lucidene 198 (ex. Dow)aqueous styrene/acrylic emulsion binder. Thor Acticide MBS (ex. Thor)water based formulation of 2-methyl-4-isothiazolin-3-one (MIT) and 1,2-benzisothiazolin-3-onebiocide Agitan 350 (ex. Munzing)blend of modified fatty and alkoxylated compounds, silica, nonionic, surfactant-dispering aid. Fructose (ex. Aldrich)charrable sugar Sucrose (ex. Aldrich)charrable sugar Sodium metaborate tetrahydrate (ex. Aldrich)basic salt.

(5) TABLE-US-00001 Comparative formulation 1 (TAG/Leuco dye) Joncryl LMV7085 28 wt % Water 21 wt % Dispex A40 0.5 wt % r-ITO 1 wt % ETAC (halochromic leuco dye) 16.5 wt % Benzyl p-hydroxybenzoate (TAG) 33 wt %

(6) The comparative ink formulation 1 was applied to clay coated cardboard using a flexographic printing technique at 10 cm.sup.3/m.sup.2 Anilox. Subsequently, the coated substrate was subject to melt extrusion lamination at speed of 500 m/min with polyethylene (12 g/m.sup.2) at 325 C. The effect of lamination on the background color of the coating was assessed using a Gregtag MacBeth SpectroEye 5000 spectrophotometer (D65, 2). A color difference (before and after lamination) according to 1976 CIE (L*, a*, b*) space, wherein E={square root over ((L*.sub.2L*.sub.1).sup.2+(a*.sub.2a*.sub.1).sup.2+(b*.sub.2b*.sub.1).sup.2)}, E=16 was obtained, showing that lamination provided a significant discoloration. The larger E value the greater the difference in colour between two samples. A E<1, in theory, represents a difference in colour that cannot be noticed by the hypothetical standard observer.

(7) Although a marking with good ODB exceeding 1.0 anyhow could be obtained via imaging using a 5 W, 1550 nm fibre laser (fluence range of 0 to 5 J/cm.sup.2 (100% speed)) fitted with a galvo mirror based imaging head, linked to a PC, subsequent to lamination, the discoloration of the coated substrate implies that ink formulations, comprising ETAC (halochromic leuco dye) and benzyl p-hydroxybenzoate (TAG), are no suitable for over lamination.

(8) As the substrate was discolored, the possible laminate puncture damage caused by laser imaging was not assessed.

(9) TABLE-US-00002 Comparative formulation 2 Water 19.8 wt % Joncryl LMV 7085 24.0 wt % Thor Acticide MBS 0.2 wt % Dispex A40 0.3 wt % Agitan 350 0.2 wt % Sucrose 13.0 wt % Fructose 5.0 wt % r-ITO 2.5 wt % Sodium Metaborate tetrahydrate 35.0 wt %

(10) The above ink was applied to clay coated cardboard substrate using a flexographic printing technique, i.e. a 14 cm.sup.3/m.sup.2 Anilox hand flexiproofer. Subsequently, the coated substrate was subject to melt extrusion lamination at speed of 500 m/min with polyethylene (12 g/m.sup.2) at 325 C.

(11) The effect of lamination on the background colour of the coating was assessed using a Gregtag MacBeth SpectroEye 5000 spectrophotometer (D65, 2). A color difference (before and after lamination) according to the 1976 CIE (L*, a*, b*) space, wherein E={square root over ((L*.sub.2L*.sub.1).sup.2+(a*.sub.2a*.sub.1).sup.2+(b*.sub.2b*.sub.1).sup.2)}, E=1.95 was obtained showing that lamination had a small effect on discolouration.

(12) The laminated substrate was then imaged using a 20 W, 1550 nm galvo driven fibre laser controlled by an IBM compatible pc. A square measuring 1 cm.sup.2 was imaged at fluence of 5 Jcm.sup.2 and a dark brown image of ODB=0.87 was obtained.

(13) Further, a red ink test was used to determine the presence of laminate puncture damage caused by laser imaging. Thus, red ink was applied by a pipette to the laminated substrates subsequent to imaging. The application did result in visible penetration of the red ink into the paperboard. Further, the possible penetration was assessed using a PIAS II device. Penetration of the ink into the board was seen, confirming that substrates coated with an ink formulation comprising charrables may not be marked without disrupting the outermost protecting polymer layer.

(14) The laminated substrates may also be assessed in accordance to ASTM F1929-98(2004) Standard Test Method for Detecting Seal Leaks in Porous Medical Packaging by Dye Penetration.

(15) TABLE-US-00003 Formulation 1 (AOM) Glascol LS2 13.5 wt % Dispelair CF49 1 wt % DEG 1 wt % Tyzor LA 1.5 wt % r-ITO 2.5 wt % Lucidene 198 25.5 wt % AOM 55 wt %

(16) The ink formulation was applied to a clay coated paper substrate using a flexographic printing technique at 12 cm.sup.3/m.sup.2 Anilox. Subsequently, the coated substrate was subject to melt extrusion lamination at speed of 500 m/min with polyethylene (12 g/m.sup.2) at 325 C. The effect of lamination on the background color of the coating was assessed using a Gregtag MacBeth SpectroEye 5000 spectrophotometer (D65, 2). A color difference (before and after lamination) of, according to the 1976 CIE (L*, a*, b*) space, wherein E={square root over ((L*.sub.2L*.sub.1).sup.2+(a*.sub.2a*.sub.1).sup.2+(b*.sub.2b*.sub.1).sup.2)}, E=0.69 was obtained, showing that lamination had a small effect on discoloration, barely noticeable to the human eye, as E<1 is typically not be noticeable to the hypothetical standard observer.

(17) It can thus be deduced that the effect on background whiteness was negligible. In comparison to the discoloration seen with Comparative formulation 1, i.e. >15, this is indeed a truly significant improvement.

(18) Subsequently a 20 W, 1550 nm fibre laser fitted with a galvo mirror based imaging head, linked to a PC, was used to create a marking on the coated/laminated substrate, showing that an ODB exceeding 1.0 (1.43 at fluence of 4.98 J/cm.sup.2) could be achieved. Thus, ink formulations comprising AOM and being overlaid by thermoplastic polymer layer, displays good printability.

(19) Further, a red ink test was used to determine the presence of laminate puncture damage caused by laser imaging. Thus, red ink was applied by a pipette to the laminated substrate subsequent to imaging. The application did not result in visible penetration of the red ink into the paperboard. Further, the possible penetration was assessed using a PIAS II device. Penetration of the ink into the board was not seen.

(20) It may thus be concluded that substrates coated with ink formulations comprising AOM may be covered with a thermoplastic polymer layer without discoloring the substrate. Further, the covered ink formulation may be marked without disrupting the outermost protecting polymer layer.

(21) The laminated substrates may also be assessed in accordance to ASTM F1929-98(2004) Standard Test Method for Detecting Seal Leaks in Porous Medical Packaging by Dye Penetration.

(22) Use of a fluence of 4.98 J/cm.sup.2, is deemed to cause heating of the ink formulations to temperatures exceeding 350 C. The finding that the polyethylene layer is not disrupted is thus truly surprising.