METHOD FOR PRODUCING A COATED PACKAGING MATERIAL

Abstract

The disclosure relates to a method for producing a coated packaging material, in particular a laminate, wherein at least the following steps are carried out: a) providing a cellulose-containing substrate, b) coating at least one surface region of the substrate with a curable composition and curing the composition, forming a primer layer, and c) generating a metal-containing layer on at least one surface region of the primer layer. According to the disclosure, the composition used in step b) contains at least one ionically polymerizable monomer that is cured via ionic polymerization. The disclosure also relates to a packaging material including a cellulose-containing substrate having a layer system, wherein the layer system has at least one primer layer and a metal-containing layer, wherein the primer layer includes/is at least one polymer cured via ionic polymerization, and a packaging produced from at least one packaging material of this type.

Claims

1. A method for producing a coated packaging material, more particularly a laminate, comprising at least the steps of: a) providing a cellulose-containing substrate; b) coating at least one surface region of the substrate with a curable composition and curing the composition to form a priming coat; and c) generating a metal-containing layer on at least one surface region of the priming coat; wherein the composition used in step b) comprises at least one ionically polymerizable monomer which is cured by ionic polymerization.

2. The method as claimed in claim 1, wherein the composition used in step b) is cured anionically or cationically and/or by living ionic polymerization.

3. The method as claimed in claim 1, wherein the composition used in step b) is cured by means of an initiator, more particularly a preferably blocked compound from the group of the Lewis and/or Brnsted acids and/or the Lewis and/or Brnsted bases, and/or by thermal and/or photochemical activation.

4. The method as claimed in claim 1, wherein the at least one ionically polymerizable monomer is selected from a group which encompasses epoxides, more particularly the cycloaliphatic epoxides and glycidyl ethers, isoprenes, cyanoacrylates, lactides, caprolactones, caprolactams, alkylcyclotrisiloxanes, vinyl ethers and isobutenes, and/or from a group which encompasses compounds having at least one electron-donating substituent, more particularly one or more alkoxy, phenyl, vinyl and/or 1,1-dialkyl groups.

5. The method as claimed in claim 1, wherein the curing in step b) is carried out at an atmospheric humidity and/or surface humidity of between 5% and 65%.

6. The method as claimed in claim 1, wherein the composition used in step b) comprises at least one polyol, more particularly from a group which encompasses polyethylene glycols, polypropylene glycols, polyethylene-propylene glycols and poly(tetrahydrofuran)diols.

7. The method as claimed in claim 1, wherein the composition used in step b) comprises nanoparticles, more particularly from the group of modified and unmodified silica particles.

8. The method as claimed in claim 1, wherein the curable composition comprises at least one solvent, more particularly a weakly polar solvent from the group of methylene chloride, toluene, apolar hydrocarbons, and tetrahydrofuran.

9. The method as claimed in claim 1, wherein the ionic polymerization is terminated by addition of at least one counterion and/or of at least one terminating reagent and/or by backbiting, and/or in that at least one second monomer type is added when the at least one monomer has reached or exceeded a predetermined degree of polymerization.

10. The method as claimed in claim 1, wherein the curable composition is applied to the substrate by means of a leveling coating process, more particularly by means of doctor, blade and/or film press and/or by means of a contour coating process, more particularly by means of casting, spraying, curtain coating and/or airbrush, and/or by a printing process, more particularly by planographic printing, gravure printing, digital printing, screen printing and/or relief printing.

11. The method as claimed in claim 1, wherein the priming coat is surface-treated before step c).

12. The method as claimed in claim 1, wherein the metal-containing layer is produced by applying and drying and/or curing a metallic paint and/or by physical and/or chemical vapor deposition, more particularly by organometallic chemical vapor deposition.

13. The method as claimed in claim 1, wherein a top layer, which more particularly is opaque or transparent, is applied to the metal-containing layer.

14. A packaging material comprising a cellulose-containing substrate having a layer system, said layer system comprising at least one priming coat and a metal-containing layer, wherein the priming coat is or comprises at least one polymer cured by bionic polymerization.

15. A package which comprises at least one packaging material which is obtainable and/or obtained by a method as claimed in claim 1.

16. A package which comprises at least one packaging material that takes the form as claimed in claim 14.

Description

[0024] Further features of the invention are apparent from the claims, the figures, and the description of the figures. The features and combinations of features stated above in the description, and also the features and combinations of features stated below in the description of the figures and/or shown in isolation in the figures, can be used not only in the combination indicated in each case but also in other combinations, without departing from the scope of the invention. Consequently, the invention should be deemed to embrace and disclose additionally embodiments that are not explicitly shown and elucidated in the figures but are apparent from and can be generated by separate combinations of features from the embodiments that are elucidated. The disclosure should also be deemed to encompass embodiments and combinations of features which, therefore, do not have all of the features of an originally formulated independent claim. Here, the single FIGURE shows a schematic sectional view from the side of a packaging material of the invention, according to one working example.

[0025] The single FIGURE shows a schematic sectional view from the side of a packaging material 10 of the invention, according to one working example. The packaging material comprises a substrate 12, which of a cellulose-containing base material 14 and comprises an inside 16 facing away from the packaged contents, and an outside 18 facing away from the packaged contents. In the present working example, the base material 14 comprises uncoated paper having a mass per unit area of about 100 g/m.sup.2. On the outside 18 of the substrate 12 there is a layer system 20 which comprises a priming coat 22, a metal-containing layer 24, and a top layer 26. To produce the priming coat 22, which in principle may also be referred to a primer, the substrate 12 was coated with a composition containing a cationically polymerizable monomer which was cured by irradiation with UV light. The monomer used was the cycloaliphatic epoxy resin 7-oxa-bicyclo[4.1.0]heptan-3-ylmethyl 7-oxa-bicyclo[4.1.0]heptane-3-carboxylate with the formula

##STR00001##

together with a photoinitiator based on antimony hexafluoride and having the formula

##STR00002##

[0026] Alternatively or additionally it is also possible in principle to use other epoxides and/or vinyl resin-based monomers. The cationic polymerization starts by opening of the epoxide rings, and brings about ongoing chain growth. The contraction during the polymerization was in this case at most 3%, meaning that adhesion of the substrate 12 was excellent. Because of the insensitivity of the cationic polymerization toward oxygen, it was possible to carry out the reaction without a protective gas atmosphere. The atmospheric humidity was set at about 30%. In addition, even prior to the UV irradiation, the composition was heated to a temperature of about 45 C. or more by means of an infrared heat source in order to achieve an increase in the reaction rate. The temperature of the substrate 12 was held at not less than 40 C. until the end of the polymerization, in order to ensure complete through-curing of the priming coat 22. As well as very good flexibility, the priming coat 22 also possesses high abrasion resistance and also a very high luster owing to the uniform surface, thereby considerably boosting not only the adhesion but also the luster and the reflection of the metal-containing layer 24 applied subsequently. The composition for the priming coat 22, the metal-containing layer 24, and the concluding, fundamentally optional top layer 26 were each applied by printing. To produce the metal-containing layer 24, a conventional metallic paint was applied and cured. An alternative option is for the metallic paint as well to comprise an ionically polymerizable monomer as curing agent, allowing covalent attachment to the priming coat 22, optionally. The top layer 26 consists of a transparent clearcoat varnish, and protects the underlying layers of the layer system 20 from environmental effects.

[0027] It will be appreciated that the layer system 20 may also be generated only on the inside 16 or both on the inside 16 and on the outside 18. In that case, moreover, layer systems 20 generated on the inside 16 and on the outside 18 may be alike or different.

[0028] The parameter values reported in the documents for the definition of process conditions and measurement conditions for the characterization of specific properties of the subject matter of the invention should be regarded as being encompassed by the scope of the invention even within the scope of deviationsresulting, for example, from measurement errors, system errors, weighing errors, DIN tolerances and the like.