COMPOSITION FOR APPLYING A MULTILAYER COATING ON A SUBSTRATE

Abstract

A solvent borne coating composition comprising: from 15-40 wt. % of a polyester resin, from 5-15 wt. % of a guanamine formaldehyde resin having no polyester groups, from 22-72 wt. % solvents with a boiling point of 50-98° C. and a curing catalyst. The composition is advantageously used of the application of multiple coloured layers on a metal or metal alloy foil. After the application of the composition, the metal or metal alloy foil can be further processed.

Claims

1. A solvent borne coating composition comprising: i) from 15-40 wt. % of a polyester resin, ii) from 5-15 wt. % of a guanamine formaldehyde resin having no polyester groups, iii) from 22-72 wt. % of one or more solvents having an atmospheric pressure boiling point of 50-98° C. and iv) a curing catalyst, wherein the wt. % is relative to the total weight of the composition.

2. The solvent borne coating composition of claim 1 comprising less than 8 wt. % solvents with an atmospheric pressure boiling point of >120° C.

3. The solvent borne coating composition of claim 1, wherein at least 75 wt. % of the polyester resin has an acid value of 0.5-10 mg KOH/g and a hydroxyl value of 0.5-100 mg KOH/g.

4. The solvent borne coating composition of claim 1, wherein at least 75 wt. % of the polyester resin is represented by a linear saturated polyester resin having a Tg below 90° C., where the Tg is measured by using differential scanning calorimetry (DSC).

5. The solvent borne coating composition of claim 1, wherein at least 75 wt. % of the guanamine formaldehyde resin is represented by an alkylated benzoguanamine formaldehyde resin.

6. The solvent borne coating composition of claim 1, wherein the curing catalyst comprises a sulfonic acid containing compound.

7. The solvent borne coating composition of claim 1, wherein the composition further comprises at least 8 wt. % pigments.

8. A method for applying at least two coating layers on a substrate, comprising: step 1: a first layer of a coating composition according to claim 1 comprising a pigment is applied to the substrate, step 2: the thus coated substrate is heated to a peak metal temperature (PMT) of at most 100° C., step 3: after step 2, a second layer of a coating composition according to claim 1 is applied onto the first layer of the substrate, step 4: after step 3, the coated substrate is heated to a peak metal temperature (PMT) of at least 200° C.

9. The method according to claim 8, wherein the substrate is a metal foil or a metal alloy foil.

10. The method according to claim 8, wherein in step 3 the second layer is provided by a clear coat.

11. The method according to claim 8, wherein after step 3, the thus coated substrate is heated to a peak metal temperature (PMT) of at most 100° C. and thereafter but before step 4 the coated substrate is further mechanically treated by coiling.

12. The method according to claim 8, wherein after step 3 but before step 4 at least one further pigment containing coating composition is applied onto the coated substrate and thereafter but before step 4 the thus coated substrate is heated to a peak metal temperature (PMT) of at most 100° C., said further pigment containing coating composition comprising: i) from 15-40 wt. % of a polyester resin, ii) from 5-15 wt. % of a guanamine formaldehyde resin having no polyester groups, iii) from 22-72 wt. % of one or more solvents having an atmospheric pressure boiling point of 50-98° C., iv) a curing catalyst, and v) a pigment, wherein the wt. % is relative to the total weight of the pigment containing coating composition.

13. An intermediate industrial prepared according to the method of claim 8, with the proviso that said method stops after step 3 but before step 4 by heating the coated substrate to a peak metal temperature (PMT) of at most 100° C., followed subsequently by step 4.

14. The product of claim 13 which is provided by a coil.

15. An article produced by a method according to claim 8.

16. An article according to claim 15 which forms an assembly part of a brewing container, said assembly part having been mechanically treated by deep drawing.

Description

EXAMPLES

[0060] The following compositions were prepared by mixing the ingredients mentioned in table 1 at room temperature until a homogeneous coating composition was obtained.

TABLE-US-00001 TABLE 1 Ingredients of the compositions in parts by weight Example Ingredient 1 2 3 4 5 6 Resin 1 .sup.1 35.2 21.4 28.6 27.8 27.8 17.1 Resin 2 .sup.2 10.0 10.0 10.0 10.0 10.0 10.0 MEK .sup.3 54.8 36.0 46.8 45.8 45.8 29.6 DDBSA .sup.4 0.5 0.5 0.5 0.5 0.5 0.5 White pigment(s) .sup.5 30.0 1.0 10 2.0 43.0 Yellow pigment .sup.6 1.8 0.2 Orange pigment .sup.7 0.6 0.2 Red pigment .sup.8 13.1 1.8 Blue pigment .sup.9 6.1 Green pigment .sup.10 1.1 Black pigment .sup.11 10.0 Rheology agent .sup.12 0.3 0.3 0.3 0.3 0.3 Color Clear Yellow Red Blue Black White .sup.1 a linear saturated polyester resin with a Mw of 18000, a Tg of 70° C., an OH value of 6 mg KOH/g and an acid value of 2 mg KOH/g. .sup.2 a n-butylated benzoguanamine resin .sup.3 methyl ether ketone solvent .sup.4 Dodecylbenzene sulfonic acid .sup.5 Titanium dioxide and/or barium sulfate .sup.6 PY 93, and/or PY 95, and/or PY 180, and/or PY 110 .sup.7 C.I. Pigment orange 64 .sup.8 Pigment red 101 .sup.9 Phthalocyanin blue .sup.10 Phthalocyanin green .sup.11 C.I. Pigment black 11 .sup.12 Hydrophilic fumed silica

Example 7

[0061] The compositions above were applied in various layers in a Rotomec printing machine operating at a speed of 100 m/min to an 8011 aluminum foil type. The compositions were each applied applied at an amount of 2 g/m.sup.2. After application of the composition(s) the foil was heated to a peak metal temperature of 90° C. for 5 sec. and rolled at 60° C. The coil was unrolled and heated to a peak metal temperature of 216° C. in an oven. Thereafter a portion packs were produced by deep drawing the coated aluminum foils in a standard deep drawing press. All portion packs showed an equal coloration over the complete part of the drawn substrate.