Method for bonding substrates, wherein the bonding is an adhesive bond which is separable by a heat treatment at a temperature of 50°C to less than 200°C and, for preparing the adhesive bond, a composition comprising a polymer of the formula, Q-(O-C -CR'R"-C -R 1) x with Q = polymer radical selected from polyester and/or polyolefin radical, wherein the polymer radical contains no building blocks resulting from the use, as monomers, of molecules having (meth)acrylic acid units, x is greater than or equal to 1, preferentially 1 to 100, preferably 2 to 20, particularly preferably 3 to 10, R 1 = R 2 or O-R 3, R 2 = hydrocarbon radical which may be substituted with halogen atoms, having 1 to 10 carbon atoms, preferentially 1 to 7 carbon atoms and preferably 1 to 4 carbon atoms, R 3 = hydrocarbon radical which may be substituted with halogen atoms, having 1 to 10 carbon atoms, preferentially having 1 to 7 carbon atoms and preferably having 1 to 4 carbon atoms, or polymer radical, preferentially selected from polyester or polyolefin radical, preferably a polymer radical which contains no building blocks resulting from the use, as monomers, of molecules having (meth)acrylic acid units, R' = -H, hydrocarbon radical which may be substituted with halogen atoms, having 1 to 10 carbon atoms, preferentially 1 to 7 carbon atoms and preferably 1 to 4 carbon atoms, or a radical of the formula, -C -NH-Q' with Q' = organic radical which may also have one or more silicon atoms, preferentially organic radical which has one or more -C -NH building blocks, -N=C=O radicals or radicals of the formula, and preferably polyester and/or polyolefin radical which has one or more -C -NH building blocks or -N=C=O radicals or radicals of the formula, with R 6 being a hydrocarbon radical which may also have nitrogen, sulfur and/or oxygen, R 6' and R 6" being identical or different saturated hydrocarbon radicals, preferentially linear hydrocarbon radicals, preferentially having 1 to 18 carbon atoms, preferably having 1 to 3 carbon atoms, and x' = 0 to 3, y' = 0 to 3, with the proviso that x' + y' = 3, and wherein the wavy line is a covalent bond to the nitrogen, wherein x' >= 2 and y' <= 1 is preferable and x' = 3 and y' = 0 is particularly preferable, R" = -H or a radical of the formula, with the proviso that, if neither of the radicals R' and R" is a radical of the formula, at least one of the radicals R' or R" is -H, is used. Q = polymer radical selected from polyester and/or polyolefin radical, wherein the polymer radical contains no building blocks resulting from the use, as monomers, of molecules having (meth)acrylic acid units, x is greater than or equal to 1, preferentially 1 to 100, preferably 2 to 20, particularly preferably 3 to 10, R 1 = R 2 or O-R 3, R 2 = hydrocarbon radical which may be substituted with halogen atoms, having 1 to 10 carbon atoms, preferentially 1 to 7 carbon atoms and preferably 1 to 4 carbon atoms, R 3 = hydrocarbon radical which may be substituted with halogen atoms, having 1 to 10 carbon atoms, preferentially having 1 to 7 carbon atoms and preferably having 1 to 4 carbon atoms, or polymer radical, preferentially selected from polyester or polyolefin radical, preferably a polymer radical which contains no building blocks resulting from the use, as monomers, of molecules having (meth)acrylic acid units, R' = -H, hydrocarbon radical which may be substituted with halogen atoms, having 1 to 10 carbon atoms, preferentially 1 to 7 carbon atoms and preferably 1 to 4 carbon atoms, or a radical of the formula, -C -NH-Q' with Q' = organic radical which may also have one or more silicon atoms, preferentially organic radical which has one or more -C -NH building blocks, -N=C=O radicals or radicals of the formula, and preferably polyester and/or polyolefin radical which has one or more -C -NH building blocks or -N=C=O radicals or radicals of the formula, with R 6 being a hydrocarbon radical which may also have nitrogen, sulfur and/or oxygen, R 6' and R 6" being identical or different saturated hydrocarbon radicals, preferentially linear hydrocarbon radicals, preferentially having 1 to 18 carbon atoms, preferably having 1 to 3 carbon atoms, and x' = 0 to 3, y' = 0 to 3, with the proviso that x' + y' = 3, and wherein the wavy line is a covalent bond to the nitrogen, wherein x' >= 2 and y' <= 1 is preferable and x' = 3 and y' = 0 is particularly preferable, R" = -H or a radical of the formula, with the proviso that, if neither of the radicals R' and R" is a radical of the formula, at least one of the radicals R' or R" is -H, is used.