Water-based printing ink comprising an aqueous dispersed polyurethane binder and an aqueous dispersed poly(meth)acrylate binder

Abstract

Provided herein is a printing ink comprising at least two binders, at least one pigment, an aqueous carrier, and optional additives, wherein one binder is a specific polyurethane dispersion binder and a further binder is a specific poly(meth)acrylate dispersion binder.

Claims

1. A water-based printing ink comprising at least two binders, at least one pigment, and an aqueous carrier, wherein at least one first binder of the at least two binders is a polyurethane dispersion binder and at least one second binder of the at least two binders is a poly(meth)acrylate dispersion binder, wherein the polyurethane dispersion binder is made of components comprising: a) at least one diisocyanate; b) at least one diol having number average molecular weight of from 500 to 5000 g/mol; and c) at least one mono-hydroxy functional compound having a number average molecular weight of from 500 to 5000 g/mol; and wherein the poly(meth)acrylate dispersion binder has a glass transition temperature between 20 and +40 C. and is prepared by polymerization of components comprising: d) at least one vinyl monomer selected from the group consisting of: acrylates, methacrylates, and styrene; and e) 0.1 to 4 wt % of one or more vinyl monomers with an acid group; and wherein the polyurethane dispersion binder and the poly(meth)acrylate dispersion binder are present in a weight ratio from 1:9 to 9:1.

2. The water-based printing ink according to claim 1, wherein the component (a) is selected from the group consisting of: 1-isocyanato-3,5,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI), tetramethylxylylene diisocyanate (TMXDI), hexamethylene diisocyanate (HDI), bis(4-isocyanatocyclohexyl)methane (HMDI), and mixtures thereof.

3. The water-based printing ink according to claim 1, wherein the component (c) is at least one monohydroxy-poly(alkylene oxide) compound having a number average molecular weight of from 500 to 5000 g/mol, wherein an alkylene of the at least one monohydroxy-poly(alkylene oxide) compound is at least one of ethylene and propylene.

4. The water-based printing ink according to claim 3, wherein the polyurethane dispersion binder comprises component (c) in an amount from 4% to 15% by weight based on weight of the polyurethane dispersion binder.

5. The water-based printing ink according to claim 1, wherein the polyurethane dispersion binder comprises components (b) and (c) together in an amount of at least 75% by weight based on weight of the polyurethane dispersion binder.

6. The water-based printing ink according to claim 1, wherein the component (b) is selected from the group consisting of: (b1) polyesterdiols comprising at least one dicarboxylic acid of the formula HOOC(CH2)yCOOH, wherein y is a number from 1 to 20, and at least one polyhydric alcohol selected from the group consisting of: compounds of the formula HO(CH2)xOH, wherein x is a number from 1 to 20, neopentyl glycol, and mixtures thereof, (b2) at least one polyetherdiol, and mixtures of (b1) and (b2).

7. The water-based printing ink according to claim 1, wherein the polyurethane dispersion binder further comprises a component (d3) comprising at least one polyfunctional compound comprising of at least three NCOgroups or at least three NCO-reactive groups.

8. The water-based printing ink according to claim 1, wherein the polyurethane dispersion binder further comprises a component (f) comprising at least one NCO-reactive group and at least one of an ionic group and an ionizable group, and wherein the at least one component (f) is a diamino acid compound, and wherein the diamino acid is selected from the group consisting of: diamino carboxylic acid compounds, diamino sulfonic acid compounds, N-(2-aminoethyl)-2-aminoethane-sulfonic acid, N-(2-aminoethyl)-2-aminoethanecarboxylic acid, and corresponding alkali metal salts of N-(2-aminoethyl)-2-aminoethane-sulfonic acid and N-(2-aminoethyl)-2-aminoethanecarboxylic acid.

9. The water-based printing ink according to claim 1, wherein the polyurethane dispersion binder comprises: 5 to 30% by weight of the component (a), which is selected from the group consisting of: 1-isocyanato-3,5,5-trimethyl-5-isocyanatomethylcyclohexane(IPDI),tetramethylxylylene diisocyanate (TMXDI), hexamethylene diisocyanate (HDI), bis(4-isocyanatocyclohexyl)methane (HMDI), and mixtures thereof; 10 to 80% by weight of the component (b) which is selected from the group consisting of: (b1) polyesterdiols made from at least one dicarboxylic acid of the formula HOOC(CH2)yCOOH, where y is a number from 1 to 20, and at least one polyhydric alcohol selected from the group consisting of compounds of the formula HO(CH2)xOH, where x is a number from 1 to 20, and neopentyl glycol, and mixtures thereof, (b2) at least one polyetherdiol, and mixtures of (b1) and (b2); 1 to 20% by weight of the component (c); 0 to 10% by weight of at least one polyamine compound having at least three amino groups; 0 to 10% by weight of at least one diamine having no acid groups 0.5 to 10% by weight of at least one diamino acid compound selected from the group consisting of diamino carboxylic acid compounds, diamino sulfonic acid compounds, N-(2-aminoethyl)-2-aminoethane-sulfonic acid, N-(2-aminoethyl)-2-aminoethanecarboxylic acid, and corresponding alkali metal salts of N-(2-aminoethyl)-2-aminoethane-sulfonic acid and N-(2-aminoethyl)-2-aminoethanecarboxylic acid; and 0 to 20% by weight of one or more polyol compounds having a number average molecular weight of less than 500 g/mol.

10. The water-based printing ink according to claim 1, wherein the water-based printing ink comprises 8 to 60% by weight of the at least two binders, 3 to 30% by weight of pigments, 15 to 60% of water, and 0.1 to 5% by weight of additives selected from the group consisting of surfactants, antifoam agents, and waxes.

11. The water-based printing ink according to claim 1, wherein the poly(meth)acrylate dispersion binder is polymerized in the presence of at least one anionic surfactant in an amount of from 0.05 to 5 parts per 100 parts by weight of monomers.

12. The water-based printing ink according to claim 1, wherein the poly(meth)acrylate dispersion binder comprises the at least one vinyl monomer (d) in an amount of at least 60% by weight, based on weight of the total amount of vinyl monomers of the poly(meth)acrylate and vinyl monomer (d) comprises a mixture of at least one soft monomer (d1) comprising 25 to 75% by weight, based on weight of the total amount of vinyl monomers of the poly(meth)acrylate and at least one hard monomer (d2) comprising 20 to 70% by weight, based on weight of the total amount of vinyl monomers of the poly(meth)acrylate, wherein soft monomers are monomers having a glass transition temperature of below 0 C. when polymerized as homopolymers, and hard monomers are monomers having a glass transition temperature of above 0 C. when polymerized as homopolymers.

13. The water-based printing ink according to claim 1, wherein the poly(meth)acrylate dispersion binder is made of components comprising: (d1) 25 to 75 wt % of at least one soft vinyl monomer selected from the group consisting of: ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate; d2) 20 to 70 wt % of at least one hard vinyl monomer selected from the group consisting of: methyl acrylate, methyl methacrylate, and styrene; the component (e) further comprising 0.5 to 4 wt % of (meth)acrylic acid; and (f) 0 to 5 wt. % of one or more nonionic, hydrophilic vinyl monomers with a water solubility of more than 100 g/L at 20 C. and selected from the group consisting of: acrylamide, methacrylamide, hydroxyethylacrylate, and hydroxyethylmethacrylate; wherein the sum of weight percentages of monomers (d1) and (d2) is at least 80% by weight.

14. The water-based printing ink according to claim 7, wherein the component (d3) is a triamine compound.

15. A printed laminate printed with the water-based printing ink of claim 1 on at least a part of a surface of the printed laminate.

16. The printed laminate of claim 15, wherein the printed laminate comprises at least two polymer films, wherein the at least two polymer films are laminated with a lamination adhesive, and wherein the water-based printing ink is disposed between the at least two laminated polymer films.

17. The printed laminate of claim 16, wherein at least one of the at least two polymer films comprises a material selected from the group consisting of: polypropylene, polyethylene terephthalate, polyamide, and low density polyethylene.

18. A method of making a printed laminate, the method comprising: applying at least one lamination ink including a water-based printing ink as defined in claim 1 to at least a part of a surface of a first polymer film by a roll printing process; and laminating a printed or unprinted second polymer film to the lamination ink-bearing surface of the first polymer film by use of an adhesive.

19. The method of claim 18, wherein the material of at least one of the first and the second polymer film is selected from the group consisting of: polypropylene, polyethylene terephthalate, polyamide, and low density polyethylene.

20. A method of using the water-based printing ink according to claim 1 for one of printing on flexible substrates and as lamination printing ink for making printed laminates.

Description

EXAMPLES

(1) Polyarylate Dispersions (PAD)

(2) PAD1

(3) Precharge a stirred 2 liter glass polymerization reactor with 331 g deionized water 6.25 g Disponil LDBS 20 (sodium n-alkyl-(C10-C13) benzene sulphonate emulsifier), flush with Nitrogen and heat to 85 C. Quickly add a solution of 3 g Ammoniumperoxodisulfat and 1.25 g sodium hydrogen carbonate in 62 g demineralized water and hold for 5 min. Add during 110 min from a stirred addition tank an emulsion prepared from 110 g water, 56.3 g Disponil LBDS 20, 290 g n-butylacrylate, 189 g methyl methacrylate, 1 g acrylic acid, and 20 g acetacetoxy ethyl acrylate. Keep for another 30 min at 85 C. Cool to 80 C. Add during 60 min as separate feeds 3 g o a 10% aqueous solution of t-butylhdroperoxid and 3.8 g of a 13% aqueous solution of sodium acetone bisulfite. Keep for another 30 min at 80 C. Cool to 35 C., adjust pH to 7.8 by adding required amount of 25% aqueous ammonia solution. Filter through 125 m filter mesh.

(4) Solids content by gravimetric determination: 47.8%

(5) pH.: 7.8

(6) Particles size 126 nm by dynamic light scattering (DLS)

(7) Glas transition temperature (Tg) of a dried polymer dispersion film by Differential Scanning calorimetry (DSC): 0 C.

(8) PAD2

(9) Precharge a 2 liter polymerization reactor with 390 g deionized water and 9.1 g of a 30 nm polystyrene seed emulsion having a solids content of 30%, stabilized with 20 wt % solid/solid sodium dodecyl sulfate. Flash the reactor with nitrogen and heat to 80 C. Add 36 g of a 7 wt % aqueous solution of ammonium peroxodisulfate. Feed monomer mixture A, consisting of 87.5 g ethyl acrylate, 12.5 g acrylic acid and 0.6 g ethylhexyl thioglycolate as chain transfer agent during 45 min at 80 C. After 5 min hold time, start feeding monomer mixture B, consisting of 240 g methyl methacrylate and 240 g n-butyl acrylate during 3 h. During these 3 h, the temperature is raised from 80 C. to 95 C. 30 min after starting the feed of monomer mixture B, a 2 wt % aqueous ammonia solution is fed to the reactor during 2.5 h. After the end of mixture B and ammonia feed, 15 g of a 2 wt % aqueous ammonia solution and 5.7 g of a 7 wt % aqueous solution of sodium peroxodisulfate is added during 15 min. Then, a solution of 1 g sodium bisulfite in 10.8 g water is added in a shot and the polymerization mixture kept at 95 C. for 30 min. After cooling to 30 C., the dispersion is filtered using a 125 m filter bag.

(10) Solid content 48.9%,

(11) pH=8.5

(12) Particle size measured by Dynamic light scattering=156 nm

(13) Tg of a dried film measured by DSC=13 C.

(14) PAD3

(15) Same procedure as example PAD2, with monomer mixture B consisting of 300 g ethyl acrylate and 100 g styrene.

(16) Solid content 48.9%,

(17) pH=7.5

(18) Particle size measured by Dynamic light scattering=147 nm

(19) Tg of a dried film measured by DSC=10 C.

(20) PAD4

(21) In a 2 l polymerization reactor equipped with an anchor stirrer, 363 g of demineralized water and 2.6 g of Disponil LBDS20 are precharged and heated to 85 C. A solution of 2.5 g Ammonium Peroxodisulfate is added. After 5 min, a mixture of 250 g n-butyl acrylate, 175 g methyl methacrylate and 62.5 g styrene is added over 2 h. Parallel to this addition a mixture of 100 g demineralized water, 39 g Disponil FES77 and 20 g of a 50 wt-% aqueous solution of acrylamide is added over 2 h while maintaining the temperature of the stirred reaction mixture at 85 C. After the addition, the mixture is stirred for 30 min at 85 C. and then cooled to 80 C. Over the course of 1 h, 3 g of a 10% solution of t-butyl hydroperoxide and 3.82 g of a 13% aqueous solution of Acetonbisulfite are added. The mixture is cooled to 35 C., neutralized to pH 8.5 by addition of 1.6 g of 25% aqueous solution of ammonia and filtered through 125 m filter mesh.

(22) pH 8.5

(23) particle size by DLS: 133 nm,

(24) Glass transition temperature (Tg) of dried film measured by DSC (midpoint of second heating curve) is 17 C.

(25) PAD5 (Comparative; 5 wt. % Acrylic Acid)

(26) Same procedure as PAD2, with monomer mixture A consisting of 75 g ethyl acrylate, 30 g acrylic acid and 0.6 g ethylhexyl thioglycolate and mixture B consisting of 240 g methyl methacrylate and 240 g n-butyl acrylate.

(27) Solid content 49.1%,

(28) pH=6.5

(29) Particle size measured by Dynamic light scattering=282 nm

(30) Tg of a dried film measured by DSC=17 C.

(31) Polyurethan Dispersions (PUD)

(32) Materials:

(33) poly(ester)polyol: based on adipic acid, neopentylglycol, 1,6-hexanediol, OH number 56 mg KOH/g polymer.

(34) Poly(tetrahydrofuran)diol: PolyTHF 2000, OH number 57 mg KOH/g polymer, molecular weight 1950-2050 g/mol

(35) methyl-started polyethylene glycol: desalted, OH number 28 mg KOH/g polymer

(36) butanol-started polyethyleneglycol: OH number 28 mg KOH/g polymer, molecular weight 2158 g/mol

(37) PUD1

(38) 200 g of polyester (based on adipic acid, neopentylglycol, 1,6-hexanediol, OH number=56 mg KOH/g polymer), 200 g of PolyTHF 2000 and 78 g of a butanol-started polyethylene glycol (OH number 28 mg KOH/g polymer) are charged in the reaction vessel along with 0.2 g of bismuth neodecanoate. The mixture is heated at an internal temperature of 60 C. and a mixture of isophorone diisocyanate (46 g) and di(4,4-isocyanatocyclohexyl)methane (54 g) is added. Acetone (48 g) is added and the mixture is heated to reflux. One hour and 30 min after the beginning of reflux, 1,4-butanediol (4.3 g) is added and the reaction is further stirred at reflux. 30 min after the addition of 1,4-butanediol the reaction mixture is diluted with acetone (468 g). At an internal temperature of 50 C., a 40% water solution of N-(2-aminoethyl)-2-aminoethane carboxylic acid sodium salt (27 g) is added over 5 min, and the mixture is stirred for 5 min. The reaction mixture is dispersed by addition of water (588 g) within 15 min. A 6.5% aqueous solution of diethylentriamine (92 g) is added within 10 min. A distillation under reduced pressure is performed for removal of acetone.

(39) Solids content by gravimetric determination: 42.2%,

(40) pH of 9.8

(41) Particle size measured by DLS: 140 nm.

(42) PUD2

(43) Dispersion was produced in an analogous manner to PUD1. Monomer mixture:

(44) TABLE-US-00001 Polyester-polyol 190.25 g PolyTHF 2000 190.25 g methyl-started polyethyleneglycol (OH number 28 mg KOH/g 71 g polymer) Bismuth neodecanoate 0.25 g Isophorone diisocyanate 44.8 g Di(4,4-isocyanatocyclohexyl)methane 53.3 g 1,4-butanediol 4.23 g N-(2-aminoethyl)-2-aminoethane carboxylic acid sodium salt 10.2 g Diethylenetriamine 5.9 g Solids: 43.2% pH: 10 Particle size by DLS: 101 nm
PUD3

(45) Dispersion was produced in an analogous manner to PUD1. Monomer mixture:

(46) TABLE-US-00002 Polyester-polyol 435.3 g Trimethylolpropan 3.6 g butanol-started polyethyleneglycol (OH number 28 mg KOH/g 65.7 g polymer) Bismuth neodecanoate 0.25 g Isophoronediisocyanate 38.5 g di(4,4-isocyanatocyclohexyl)methane 45.7 g Diethylenetriamine 5 g Solids: 47.3 pH: 9.0 particle size by DLS: 119 nm
PUD4

(47) 406 g of polyester (based on adipic acid, neopentylglycol, 1,6-hexanediol, OH number=56 mg

(48) KOH/g polymer), 74 g of a butanol-started polyethyleneglycol (OH number 28 mg KOH/g polymer), 4.05 g of Trimethylolpropan and 6.55 g dimethylol propionic acid are charged in the reaction vessel along with 0.25 g of bismuth neodecanoate. The mixture is heated at an internal temperature of 60 C. and a mixture of isophoronediisocyanate (43 g) and di(4,4-isocyanato-cyclohexyl)methane (51.4 g) is added. Acetone (50 g) is added and the mixture is heated to reflux. Two hours after the beginning of reflux, the reaction mixture is diluted with acetone (482 g). At an internal temperature of 50 C., 2-Dimethylethanolamin (4.36 g) is added and with 5 g water over 11 min diluted. The reaction mixture is dispersed by addition of water (588 g) within 15 min. A 6.5% water solution of diethylentriamine (87 g) is added within 10 min. A distillation under reduced pressure is performed for removal of acetone.

(49) Solids: 38%

(50) pH: 9.2

(51) particle size by DLS: 80 nm

(52) PUD5

(53) Dispersion was produced in an analogous manner to PUD1. Monomer mixture:

(54) TABLE-US-00003 Polyester-polyol 400 g butanol-started polyethyleneglycol (OH number 28 mg KOH/g 17 g polymer) Elastostab H02 (stabilizer) 2.5 g Cesium acetate 0.025 g lsophoronediisocyanate 35.4 g di(4,4-isocyanatocyclohexyl)methane 42.9 g N-(2-aminoethyl)-2-aminoethane sulfonic acid sodium salt 11.3 g lsophoroneediamine 1.8 g Diethylentriamine 3.9 g Solids: 39.7% pH: 7.1 particle size by DLS: 220 nm

Blend Examples

(55) Any combination of any polyurethane dispersions PUD1 to PUD5 with any of polyacrylate dispersion PAD 1 to PAD 4 can be used according to the invention for preparing ink compositions.

Blend Example 1 (50:50)

(56) 250.5 g of PAD1 and 302.3 g of PUD5 are blended in a stirred vessel and diluted with 47.2 g of deionized water and adjusted to the desired pH with 25 wt-% aqueous ammonia solution

(57) solids 38.9%

(58) pH 8.9

Blend Example 2 (50:50)

(59) 245.4 g of PAD2 and 283.7 g of PUD1 are blended in a stirred vessel, diluted with 70.9 g of deionized water and adjusted to the desired pH with 25 wt-% aqueous ammonia solution

(60) Solids: 39.4%

(61) pH: 8.6

Blend Example 3 (55/45)

(62) 269.9 g of PAD2 and 284.2 g of PUD4 are blended in a stirred vessel, diluted with 45.9 g of deionized water and adjusted to the desired pH with 25 wt-% aqueous ammonia solution

(63) Solids: 40.0%

(64) pH: 8.6

Example 4 (50/50)

(65) 243.4 g of PAD4 and 277.8 g of PUD2 are blended in a stirred vessel, diluted with 78.8 g of deionized water and adjusted to the desired pH with 25 wt-% aqueous ammonia solution

(66) Solids: 39.3%

(67) pH: 8.9

Example 5 (65/35)

(68) 319 g of PAD3 and 177.6 g of PUD3 are blended in a stirred vessel, diluted with 103.4 g of deionized water and adjusted to the desired pH with 25 wt-% aqueous ammonia solution

(69) Solids: 39.3%

(70) pH: 8.9

Comparative Example 1

(71) A polyurethane dispersion was prepared according to the description of example 2 of WO2009/023520

(72) Solids: 33.9%

(73) pH: 8.8

(74) particle size by DLS: 108 nm

Comparative Example 2 (50/50)

(75) 244.4 g of PAD5 (comparative) and 283.7 g of PUD1 are blended in a stirred vessel, diluted with 71.9 g of deionized water and adjusted to the desired pH with 25 wt-% aqueous ammonia solution

(76) Solids: 39.3%

(77) pH: 8.7

(78) Preparation and Testing of Inks:

(79) Ink Preparation:

(80) A cyan lamination ink is prepared, upon blending 30 parts by weight of a resin-based pigment concentrate consisting of 40 wt % organic pigment PB15.3, 10% dispersing resin Joncryl HPD96, 0.5% antifoam agent (Tegofoam 810) and 48.5% water with 70 parts of the ink binder of the invention.

(81) A white lamination ink is prepared, upon blending parts of a resin-free pigment concentrate consisting of 75% titanium dioxide (Sachtleben RDI/S), 3% surfactant (Tego Dispers 750W), 0.5% antifoam (Tegofoam 810) and 21.5% water with 60 parts of the ink binder of the invention.

(82) Viscosity of the ink is measured direct after preparation of the ink, after two days at room temperature (20 C.). Ink is diluted with water to print viscosity (maximum 20-25 sec flow time in DIN4 cup) and is printed on a polyester film.

(83) TABLE-US-00004 Viscosity Viscosity Viscosity Viscosity White Ink White Ink Cyan ink Cyan ink Initial after 2 d Initial After 2 d Ink Binder DIN cup 4 [s] DIN cup 4 [s] DIN cup 4 [s] DIN cup 4 [s] Example 1 19 17 29 25 Example 2 18 17 20 18 Example 3 19 19 23 19 Example 4 18 17 19 18 Example 5 18 18 19 19 Comparative 19 15 48 67 Example 1 Comparative 77 60 58 46 Example 2
Ink Application:

(84) Ink was applied on chemically treated polyester film (Mylar 813), using a wire-bar 0 (4 m wet ink). Coloured Inks are applied in one layer for block and resolubility testing or in two layers for lamination testing. White inks are applied in one layer on polyester for blocking and resolubility or as 3rd layer on top of two layers of coloured ink for lamination testing.

(85) For one-layer print: put the printed substrate in an air circulated oven for 10 sec at 60 C. air temperature, then leave the print for 1 h at room temperature before laminating it to the secondary film or testing e.g. blocking resistance.

(86) For two-layers print: print the first colour layer, dry 10 sec at 60 C. in an air circulated oven, print the second layer of white ink, dry 10 sec at 60 C. and leave the print for 1 h at room temperature, before laminating it to the secondary film.

(87) Test of Ink Resolubility

(88) Ink is applied onto corona treated OPP using a wire-bar 1 (6 m wet coating weight) and then left to dry under different drying conditions: a) Leave for 1 min at room temperature b) Leave for 5 min at room temperature c) Leave for 10 min at room temperature d) Leave for 1 min in an air circulated oven at 60 C.

(89) After drying, a droplet of ink is put on the print and subsequently wiped off. The amount of ink removed from the original print is judged as a measure of the ability of the ink to redissolve itself, after it has been dried.

(90) TABLE-US-00005 White ink Cyan Ink Ink Binder After 10 min at RT After 10 min at RT Example 1 + + Example 2 + + Example 3 ++ + Example 4 o o Example 5 + + Comparative Example 1 -- - Comparative Example 2 ++ ++ Resolubility grades: ++ = very good, + = good, o = ok, - = poor, -- = very poor
Preparation of Printed Laminates:

(91) In order to test the lamination bond strengths, the prints on chemically treated PET were laminated to standard LDPE (Low-density Polyethylene) with a 2-component polyurethane lamination adhesive to give PET//LDPE laminates.

(92) Preparation of the 2 component polyurethane lamination adhesive:

(93) Liofol Hardener UR6080: 8.0 weight parts (obtained from Henkel Industrial Adhesives)

(94) Liofol UR7780: 20.0 weight parts (obtained from Henkel Industrial Adhesives)

(95) Ethyl acetate: 20.0 weight parts (solvent for ease of application)

(96) The freshly prepared adhesive is applied (using wire bar 1, 6 m wet) to the secondary (unprinted) film at a coating weight of 2.5 g/m.sup.2 (dry), and subsequently dried in the oven for 10 s at 60 C. to evaporate the solvent. The printed films are next carefully applied with the printed side to the adhesive side of the secondary films, thereby avoiding creation of air bubbles in the laminate, to give PET//LDPE laminate structures. Firmly squeeze the laminated construction, by using a 10 kg roller. The resulting laminates are stored for 3 days under pressure (ca. 0.25 kg/cm.sup.2), in order to allow the adhesive to cure.

(97) Test of Lamination Bond Strength (LBS)

(98) For measurement of lamination bond strength (=force needed to peel the laminate open), a strip of 15 mm width is cut from the cured laminate and bond strength is measured using a Lloyd Instruments tensile tester. Measurement is done at a speed of 150 mm/min. During the measurement, the laminated strip should be kept under a 90 angle against the film clamps. This test is repeated after the laminated strip has been heat-sealed at 140 C. with 400 N for 1 s using a Brugger heat sealer, in order to simulate heat-seal process. Lamination bond strength is reported in Newton per 15 mm [N/15 mm].

(99) TABLE-US-00006 LBS a of printed LBS of printed laminate laminate with two with two layers of blue ink layers of blue ink plus one layer of white ink Ink Binder [N/15 mm] [N/15 mm] Example 1 2.2 1.8 Example 2 3.0 2.4 Example 3 2.1 2.0 Example 4 DT 2.2 Example 5 2.3 1.9 Comparative Example 1 0.7 0.5 Comparative Example 2 0.9 0.7 DT: direct tear of the laminate, i.e. very high lamination bond strength, higher than material strength; due to tearing it is not possible to determine a LBS value,

(100) The examples of the invention have a lamination bond strength of more than 1 N/15 mm, preferably more than 1.5 N/15 mm.

(101) Test of Blocking Resistance:

(102) Diluted ink (diluted to a viscosity of 20-25 sec in DIN4 cup) will be printed on PET film. Coating weight applied: 1.0 g/m.sup.2 for colour ink and 1.5 g/m.sup.2 for white ink. Print will be dried in an oven: 10 sec at 60 C. After drying, a second unprinted film will be placed on top of the printed film, with the backside of the second film facing the printed side of the first printed film. Films will be placed in a Specac laboratory press and will be blocked at 5 tons/30 C./24 hrs (representing 65 kg/cm.sup.2). After removing the samples from the blocking tester, the unprinted layer film will be removed from the printed layer, and the tendency of the unprinted film to adhere to the printed film (blocking) will be judged visually and reported as Release (tackiness) and Damage (ink transfer to the unprinted film). Typical example of blocking resistance measurement results are reported below. The values go from 1 (very bad, blocking ink) to 5 (very good, blocking-free ink). Release values of 3 or higher indicate acceptable performance.

(103) TABLE-US-00007 Bock test results White on 813 Blocking test Cyan on 813 Ink Binder Release Damage Release Damage Example 1 3.5 5 5 5 Example 2 3 5 4.5 5 Example 3 3.5 5 4 5 Example 4 3.5 5 4 5 Example 5 3 5 3.5 5 Comparative Example 1 5/4.5 5 4.5 5 Comparative Example 2 5 5 5 5

(104) While comparative example 1 shows good blocking resistance, the ink resolubility and the lamination bond strength are poor.

(105) While comparative example 2 shows good blocking resistance and good ink resolubility, the lamination bond strength is poor.

(106) Inventive examples 1 to 5 show an improved balance of properties by having good or at least acceptable ink resolubilities, good lamination bond strengths and acceptable blocking resistance.