Method for producing a multi-layer substrate

A multi-layer substrate produced comprising the following steps:

• a) providing a first material having a first surface with at least one edge region and at least one inner region enclosed by the edge region;
• b) applying a coating material to partial portions of the inner region of the first surface, the coating material comprising expandable microparticles;
• c) drying the coating material;
• and
• d) contacting the first surface of the first material with a surface of a second material to form the multi-layer substrate such that the coating material is between the first material and the second material,
• wherein the inner region does not contain an adhesive
• wherein the coating material consists of:
• (i) 30 to 70 wt-% of VAE copolymer dispersion;
• (ii) 5 to 15 wt. % of paraffin dispersion;
• (iii) 15 to 30 wt. % of microparticles;
• (iv) 5 to 10 wt. % of glycerol;
• and
• (v) optionally, hydroxyethylcellulose,
• wherein the total weight of the coating material and add up to 100 wt. %.