Hot-sealable coating systems and method for joining surfaces

1. A hot-sealable coating composition, comprising:

(I) a polyurethane and/or polyurethane-polyurea polymer which is obtained by the reaction of:

(A) at least one diol and/or polyol component,

(B) at least one di- and/or polyisocyanate component,

(C) at least one component comprising sulphonate and/or carboxylate groups,

(D) optionally mono-, di- and/or tri-amino-functional and/or hydroxyamino-functional compounds,

(E) optionally other isocyanate-reactive compounds; and

(II) an olefin vinyl acetate copolymer,

wherein the polyurethane and/or polyurethane-polyurea polymer (I) has a glass transition temperature of ≦10° C.;

the glass transition temperature being determined by differential scanning calorimetry according to DIN 65467 at a heating rate of 20 K/min;

and

wherein the olefin vinyl acetate copolymer (II) has a minimum film forming temperature (white point temperature) of >40° C.;

the minimum film forming temperature being determined by differential scanning calorimetry according to DIN ISO 2115 (white point temperature) at a heating rate of 20 K/min.

2. The coating composition according to claim 1 , wherein the polyol component (A) is a linear polyester polyol.

3. The coating composition according to claim 1 , wherein the polyisocyanate component (B) is isophorone diisocyanate.

4. The coating composition according to claim 1 , wherein the component (C) is N-(2-aminoethyl)-2-aminoethane sulphonic acid and the component (D) is diethanol amine.

5. The coating composition according to claim 1 , wherein the olefin vinyl acetate copolymer (II) is ethylene vinyl acetate copolymer.

6. The coating composition according to claim 1 , wherein the polyurethane and/or polyurethane-polyurea polymer (I) has a glass transition temperature of ≧−50° C. to ≦10° C., the glass transition temperature being determined by differential scanning calorimetry according to DIN 65467 at a heating rate of 20 K/min.

7. The coating composition according to claim 1 , wherein the olefin vinyl acetate copolymer (II) has a minimum film forming temperature (white point temperature) of ≧50° C. to ≦90° C., the film forming temperature being determined according to DIN ISO 2115.

8. The coating composition according to claim 1 , wherein the polymer formed by combining the polyurethane and/or polyurethane-polyurea polymer (I) and the olefin vinyl acetate copolymer (II) has a storage modulus G′ at 50° C. and 1 rad/s of between 1*105 Pa and 1*108 Pa, the storage modulus being determined by means of oscillating rheometry in accordance with ASTM D 4440-08.

9. The coating composition according to claim 1 , wherein the coating system is present in the form of an aqueous dispersion or in the form of a solid powder.

10. A method for joining surfaces, comprising

providing a first surface and a second surface;

at least partially applying the coating composition according to claim 1 to the first and/or second surface;

contacting the first surface with the second surface so that the coating system is located between the first and the second surface to give a layered assembly;

heating the layered assembly to a temperature of ≧50° C. and simultaneously applying a pressure of ≧1 bar to the layered assembly.

11. The method according to claim 10 , wherein the first surface is an aluminum surface or polyethylene terephthalate surface or a surface made of cardboard and plastic and the second surface is a polyolefin surface.

12. The method according to claim 10 , wherein the first surface and/or the second surface have a critical surface energy σ c , determined according to DIN 55 660-2, of ≦40 mN/m.

13. The method according to claim 10 , wherein the coating system according to claim 1 is applied in the form of an aqueous dispersion and dried at a temperature of ≧20° C. to ≦70° C. prior to the next step.

14. The method according to claim 10 , wherein in the step of heating the layered assembly the layered assembly is heated to a temperature of ≧70° C. to ≦220° C.