Composite foils biodisintegratable at home compost conditions

A method providing an aqueous polyurethane dispersion adhesive for producing composite foils which are biodisintegratable at home compost conditions (25±5° C.), where at least one first substrate is adhesive-bonded to at least one second substrate with use of the polyurethane dispersion adhesive,

• wherein at least one of the substrates is a polymer foil which is biodisintegratable at home compost conditions, and where more than 80% by weight of the polyurethane is composed of
• (a) at least one diisocyanate,
• (b) at least one polyesterdiol, and
• (c) at least one bifunctional carboxylic acid selected from dihydroxy carboxylic acids and diamino carboxylic acids;
• wherein the polyurethane has a glass transition temperature below 20° C.,
• characterized in that the polyurethane either has no melting point above 20° C. or wherein the polyurethane has a melting point above 20° C. with an enthalpy of fusion lower than 10 J/g;
• wherein at least 80% by weight of the polyurethane is composed of at least one aliphatic polyesterdiol (b);
• wherein a film of the polyurethane adhesive decomposes at home compost conditions to more than 90% by weight into CO2 and water within 360 days;
• wherein a material is biodisintegratable at home compost conditions if at most 10% of the original dry weight of the material is found to be present after aerobic composting at 25±5° C. for a period of at most 180 days in a sieve fraction >2 mm.