Biodegradable polymers, the preparation thereof, and the use thereof for producing biodegradable moldings

A biodegradable polymer T1 having a molecular weight (Mn) in the range from 10,000 to 100,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polymer T1 at 25° C.) and a melting point in the range from 50 to 235° C., obtainable by reacting the polyether ester Q1 having a molecular weight (Mn) in the range from 5000 to 100,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester Q1 at 25° C.) and a melting point in the range from 50 to 235° C., obtained by reacting a mixture essentially comprising:

• (c1) polyether ester P1 obtained by reacting a mixture essentially comprising:
• (a1) a mixture essentially comprising
• 40-70 mol % of adipic acid or ester-forminq derivatives thereof or mixtures thereof,
• 30-60 mol % of terephthalic acid or ester-forming derivatives thereof or mixtures thereof, and
• 0-5 mol % of a compound containing sulfonate groups,
• where the total of the individual mole percentages is 100 mol %, and
• (a2) a mixture of dihydroxy compounds essentially comprising
• (a21) from 15 to 99.8 mol % of a dihydroxy compound selected from the group consisting of C2-C6-alkanediols and C5-C10-cycloalkanediols,
• (a22) from 85 to 0.2 mol % of a dihydroxy compound containing ether functionalities of the formula I:
• HO—((CH2)n—O)m—H I
• where n is 2, 3 or 4 and m is an integer from 2 to 250, or mixtures thereof,
• where the molar ratio of (a1) to (a2) is chosen in the range from 0.4:1 to 1.5:1, with the proviso that the polyether ester P1 has a molecular weight (Mn) in the range from 5000 to 80,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester P1 at 25° C.) and a melting point in the range from 50 to 200° C., and with the further proviso that from 0 to 5 mol %, based on the molar quantity of component (a1) employed, of a compound D having at least three groups capable of ester formation are employed to prepare the polyether ester P1
• (c2) from 0.01 to 50% by weight, based on (c1), of hydroxycarboxylic acid B1,
• where the hydroxycarboxylic acid B1 is defined by the formulae IIa or IIb:
• where p is an integer from 1 to 1500 and r is an integer from 1 to 4, and G is a radical which is selected from the group consisting of phenylene, —(CH2)k—, where k is an integer from 1 to 5, —C(R)H— and —C(R)HCH2, where R is methyl or ethyl, and
• (c3) from 0 to 5 mol %, based on the molar amount of component (a1) used for preparing P1, of compound D having at least three groups capable of ester formation,
• with (e1) from 0.1 to 5% by weight, based on the polyether ester Q1, of a diisocyanate C1 and also with (e2) from 0 to 5 mol %, based on the molar amount of component (a1) used for preparing polyether ester Q1, of compound D.

A biodegradable polymer T2 having a molecular weight (Mn) in the range from 10,000 to 100,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polymer T2 at 25° C.) and a melting point in the range from 50 to 235° C., obtained by reacting the polyether ester Q2 having a molecular weight (Mn) in the range from 5000 to 100,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester Q1 at 25° C.) and a melting point in the range from 50 to 235° C., obtained by reacting a mixture essentially comprising:

• (d1) from 95 to 99.9% by weight of polyether ester P1 obtainable by reacting a mixture essentially comprising:
• (a1) a mixture essentially comprising
• 40-70 mol % of adipic acid or ester-forminq derivatives thereof or mixtures thereof,
• 30-60 mol % of terephthalic acid or ester-forming derivatives thereof or mixtures thereof, and
• 0-5 mol % of a compound containing sulfonate groups,
• where the total of the individual mole percentages is 100 mol %, and
• (a2) a mixture of dihydroxy compounds essentially comprising
• (a21) from 15 to 99.8 mol % of a dihydroxy compound selected from the group consisting of C2-C6-alkanediols and C5-C10-cycloalkanediols,
• (a22) from 85 to 0.2 mol % of a dihydroxy compound containing ether functionalities of the formula I:
• HO—((CH2)n—O)m—H I
• where n is 2, 3 or 4 and m is an integer from 2 to 250, or mixtures thereof,
• where the molar ratio of (a1) to (a2) is chosen in the range from 0.4:1 to 1.5:1, with the proviso that the polyether ester P1 has a molecular weight (Mn) in the range from 5000 to 80,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester P1 at 25° C.) and a melting point in the range from 50 to 200° C., and with the further proviso that from 0 to 5 mol %, based on the molar quantity of component (a1) employed, of a compound D having at least three groups capable of ester formation are employed to prepare the polyether ester P1
• (d2) from 0.1 to 5% by weight of a diisocyanate C1 and
• (d3) from 0 to 5 mol %, based on the molar amount of component (a1) used for preparing P1, of compound D having at least three groups capable of ester formation
• with
• (f1) from 0.01 to 50% by weight, based on the polyether ester Q2, of hydroxycarboxylic acid B1,
• where the hydroxycarboxylic acid B1 is defined by the formulae IIa or IIb:
• where p is an integer from 1 to 1500 and r is an integer from 1 to 4, and G is a radical which is selected from the group consisting of phenylene, —(CH2)k—, where k is an integer from 1 to 5, —C(R)H— and —C(R)HCH2, where R is methyl or ethyl, and also with
• (f2) from 0 to 5 mol %, based on the molar amount of component (a1) used for preparing polyether ester Q2, of compound D.

A biodegradable polymer T3 having a molecular weight (Mn) in the range from 10,000 to 100,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polymer T3 at 25° C.) and a melting point in the range from 50 to 235° C., obtained by reacting

• (g1) polyether ester P2, obtained by reacting a mixture essentially comprising
• (b1) a mixture essentially comprising
• 30-70 mol % of adipic acid or ester-forminq derivatives thereof or mixtures thereof,
• 30-70 mol % of terephthalic acid or ester-forming derivatives thereof or mixtures thereof, and
• 0-5 mol % of a compound containing sulfonate groups,
• where the total of the individual mole percentages is 100 mol %,
• (b2) a mixture of dihydroxy compounds (a2), essentially comprising
• (a21) from 15 to 99.8 mol % of a dihydroxy compound selected from the group consisting of C2-C6-alkanediols and C5-C10-cycloalkanediols,
• (a22) from 85 to 0.2 mol % of a dihydroxy compound containing ether functionalities of the formula I:
• HO—((CH2)n—O)m—H I
• where n is 2, 3 or 4 and m is an integer from 2 to 250, or mixtures thereof,
• where the molar ratio of (b1) to (b2) is chosen in the range from 0.4:1 to 1.25:1,
• (b3) from 0.01 to 100% by weight, based on component (b1), of a hydroxycarboxylic acid B1, and
• (b4) from 0 to 5 mol %, based on component (b1), of compound D having at least three groups capable of ester formation,
• where the hydroxycarboxylic acid B1 is defined by the formulae IIa or IIb:
• where p is an integer from 1 to 1500 and r is an integer from 1 to 4, and G is a radical which is selected from the group consisting of phenylene, —(CH2)k—, where k is an integer from 1 to 5, —C(R)H— and —C(R)HCH2, where R is methyl or ethyl,
• where the polyether ester P2 has a molecular weight (Mn) in the range from 5000 to 80,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester P2 at 25° C.) and a melting point in the range from 50 to 235° C., or
• (g2) a mixture comprising essentially
• polyether ester P1 obtained by reacting a mixture essentially comprising:
• (a1) a mixture essentially comprising:
• 40-70 mol % of adipic acid or ester-forminq derivatives thereof or mixtures thereof,
• 30-60 mol % of terephthalic acid or ester-forming derivatives thereof or mixtures thereof, and
• 0-5 mol % of a compound containing sulfonate groups,
• where the total of the individual mole percentages is 100 mol %, and
• (a2) a mixture of dihydroxy compounds essentially comprising
• (a21) from 15 to 99.8 mol % of a dihydroxy compound selected from the group consisting of C2-C6-alkanediols and C5-C10-cycloalkanediols,
• (a22) from 85 to 0.2 mol % of a dihydroxy compound containing ether functionalities of the formula I:
• HO—((CH2)n—O)m—H I
• where n is 2, 3 or 4 and m is an integer from 2 to 250, or mixtures thereof,
• where the molar ratio of (a1) to (a2) is chosen in the range from 0.4:1 to 1.5:1, with the proviso that the polyether ester P1 has a molecular weight (Mn) in the range from 5000 to 80,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester P1 at 25° C.) and a melting point in the range from 50 to 200° C., and with the further proviso that from 0 to 5 mol %, based on the molar quantity of component (a1) employed, of a compound D having at least three groups capable of ester formation are employed to prepare the polyether ester P1and from 0.01 to 50% by weight, based on the polyether ester P1, of hydroxycarboxylic acid B1, or
• (g3) a mixture essentially comprising polyether esters P1 which differ from one another in composition,
• with 0.1-5% by weight, based on the quantity of the polyether esters employed, of a diisocyanate C1 and
• with 0-5 mol %, based on the respective molar amonmts of component (a1) or (b1) used for preparing the polyether esters (g1) to (g3) employed, of compound D.

A biodegradable thermoplastic molding composition T4 obtained by mixing in a conventional way

• (h1) 99.5-0.5% by weight of polyether ester P1 obtained by reacting a mixture essentially comprising:
• (a1) a mixture essentially comprising:
• 40-70 mol % of adipic acid or ester-forminq derivatives thereof or mixtures thereof,
• 30-60 mol % of terephthalic acid or ester-forming derivatives thereof or mixtures thereof, and
• 0-5 mol % of a compound containing sulfonate groups,
• where the total of the individual mole percentages is 100 mol %, and
• (a2) a mixture of dihydroxy compounds essentially comprising
• (a21) from 15 to 99.8 mol % of a dihydroxy compound selected from the group consisting of C2-C6-alkanediols and C5-C10-cycloalkanediols,
• (a22) from 85 to 0.2 mol % of a dihydroxy compound containing ether functionalities of the formula I:
• HO—((CH2)n—O)m—H I
• where n is 2, 3 or 4 and m is an integer from 2 to 250, or mixtures thereof,
• where the molar ratio of (a1) to (a2) is chosen in the range from 0.4:1 to 1.5:1, with the proviso that the polyether ester P1 has a molecular weight (Mn) in the range from 5000 to 80,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester P1 at 25° C.) and a melting point in the range from 50 to 200° C., and with the further proviso that from 0 to 5 mol %, based on the molar quantity of component (a1) employed, of a compound D having at least three groups capable of ester formation are employed to prepare the polyether ester P1 or polyether ester Q2 having a molecular weight (Mn) in the range from 6000 to 80,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlcrobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester Q2 at 25° C.) and a melting point in the range from 50 to 200° C., obtained by reacting a mixture essentially comprising
• (d1) from 95 to 99.9% by weight of polyether ester P1
• (d2) from 0.1 to 5% by weight of a diisocyanate C1 and
• (d3) from 0 to 5 mol %, based on the molar amount of component (a1) used for preparing P1, of compound D having at least three groups capable of ester formation, with
• (h2) from 0.5 to 99.5% by weight of hydroxycarboxylic acid B1,
• where the hydroxycarboxylic acid B1 is defined by the formulae IIa or IIb:
• where p is an integer from 1 to 1500 and r is an integer from 1 to 4, and G is a radical which is selected from the group consisting of phenylene, —(CH2)k—, where k is an integer from 1 to 5, —C(R)H— and —C(R)HCH2, where R is methyl or ethyl.

A process for preparing the biodegradable polyether esters Q2 having a molecular weight (Mn) in the range fram 6,000 to 80,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester Q2 at 25° C.) and a melting point in the range from 50 to 200° C., which comprises preparing in a first step polyether esters P1, obtained by reacting a mixture essentially comprising:

• (a1) a mixture essentially comprising:
• 40-70 mol % of adipic acid or ester-forminq derivatives thereof or mixtures thereof,
• 30-60 mol % of terephthalic acid or ester-forming derivatives thereof or mixtures thereof, and
• 0-5 mol % of a compound containing sulfonate groups,
• where the total of the individual mole percentages is 100 mol %, and
• (a2) a mixture of dihydroxy compounds essentially comprising
• (a21) from 15 to 99.8 mol % of a dihydroxy compound selected from the group consisting of C2-C6-alkanediols and C5-C10-cycloalkanediols,
• (a22) from 85 to 0.2 mol % of a dihydroxy compound containing ether functionalities of the formula I:
• HO—((CH2)n—O)m—H I
• where n is 2, 3 or 4 and m is an integer from 2 to 250, or mixtures thereof,
• where the molar ratio of (a1) to (a2) is chosen in the range from 0.4:1 to 1.5:1, with the proviso that the polyether ester P1 have a molecular weight (Mn) in the range from 5000 to 80,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester P1 at 25° C.) and a melting point in the range from 50 to 200° C., and with the further proviso that from 0 to 5 mol %, based on the molar quantity of component (a1) employed, of a compound D having at least three groups capable of ester formation are employed to prepare the polyether ester P1,
• and reacting in a second step a mixture essentially comprising from 95 to 99.9% by weight of (d1),
• (d2) from 0.1 to 5% by weight of a diisocyanate C1 and
• (d3) from 0 to 5 mol %, based on the molar amount of component (a1) used for preparing P1, of compound D.

A process for preparing the biodegradable polymers T1 having a molecular weight (Mn) in the range from 10,000 to 100,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polymer T1 at 25° C.) and a melting point in the range from 50 to 235° C., which comprises preparing in a first step polyether esters Q1 having a molecular weight (Mn) in the range from 5000 to 100,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester Q1 at 25° C.) and a melting point in the range from 50 to 235° C., obtained by reacting a mixture essentially comprising:

• (c1) polyether esters P1, obtained by reacting a mixture essentially comprising:
• (a1) a mixture essentially comprising:
• 40-70 mol % of adipic acid or ester-forminq derivatives thereof or mixtures thereof,
• 30-60 mol % of terephthalic acid or ester-forming derivatives thereof or mixtures thereof, and
• 0-5 mol % of a compound containing sulfonate groups,
• where the total of the individual mole percentages is 100 mol %, and
• (a2) a mixture of dihydroxy compounds essentially comprising
• (a21) from 15 to 99.8 mol % of a dihydroxy compound selected from the group consisting of C2-C6-alkanediols and C5-C10-cycloalkanediols,
• (a22) from 85 to 0.2 mol % of a dihydroxy compound containing ether functionalities of the formula I:
• HO—((CH2)n—O)m—H I
• where n is 2, 3 or 4 and m is an integer from 2 to 250, or mixtures thereof,
• where the molar ratio of (a1) to (a2) is chosen in the range from 0.4:1 to 1.5:1, with the proviso that the polyether esters P1 have a molecular weight (Mn) in the range from 5000 to 80,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester P1 at 25° C.) and a melting point in the range from 50 to 200° C., and with the further proviso that from 0 to 5 mol %, based on the molar quantity of component (a1) employed, of a compound D having at least three groups capable of ester formation are employed to prepare the polyether esters P1,
• (c2) 0.01-50% by weight, based on (c1), of hydroxycarboxylic acid B1,
• where the hydroxycarboxylic acid B1 is defined by the formulae IIa or IIb:
• where p is an integer from 1 to 1500 and r is an integer from 1 to 4, and G is a radical which is selected from the group consisting of phenylene, —(CH2)k—, where k is an integer from 1 to 5, —C(R)H— and —C(R)HCH2, where R is methyl or ethyl, and
• (c3) 0-5 mol %, based on the molar amount of component (a1) used for preparing P1, of compound D
• and reacting in a second step Q1
• with (e1) from 0.1 to 5% by weight, based on the polyether ester Q1, of a diisocyanate C1 and also with (e2) from 0 to 5 mol %, based on the molar amount of component (a1) used for preparing P1 and the polyether esters Q1, of compound D.

A process for preparing the biodegradable polymers T2 having a molecular weight (Mn) in the range from 10,000 to 100,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polymer T2 at 25° C.) and a melting point in the range from 50 to 235° C., which comprises preparing in a first step polyether esters Q2 having a molecular weight (Mn) in the range from 6000 to 80,000 g/mol, a viscosity mmber in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester Q2 at 25° C.) and a melting point in the range from 50 to 200° C., obtained by reacting a mixture essentially comprising:

• (d1) from 95 to 99.9% by weight of polyether esters P1, obtained by reacting a mixture essentially comprising:
• (a1) a mixture essentially comprising
• 40-70 mol % of adipic acid or ester-forminq derivatives thereof or mixtures thereof,
• 30-60 mol % of terephthalic acid or ester-forming derivatives thereof or mixtures thereof, and
• 0-5 mol % of a compound containing sulfonate groups,
• where the total of the individual mole percentages is 100 mol %, and
• (a2) a mixture of dihydroxy compounds essentially comprising
• (a21) from 15 to 99.8 mol % of a dihydroxy compound selected from the group consisting of C2-C6-alkanediols and C5-C10-cycloalkanediols,
• (a22) from 85 to 0.2 mol % of a dihydroxy compound containing ether functionalities of the formula I:
• HO—((CH2)n—O)m—H I
• where n is 2, 3 or 4 and m is an integer from 2 to 250, or mixtures thereof,
• where the molar ratio of (a1) to (a2) is chosen in the range from 0.4:1 to 1.5:1, with the proviso that the polyether esters P1 have a molecular weight (Mn) in the range from 5000 to 80,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester P1 at 25° C.) and a melting point in the range from 50 to 200° C., and with the further proviso that from 0 to 5 mol %, based on the molar quantity of component (a1) employed, of a compound D having at least three groups capable of ester formation are employed to prepare the polyether esters P1,
• (d2) from 0.1 to 5% by weight of a diisocyanate C1 and
• (d3) from 0 to 5 mol %, based on component (a1) used for the preparation of P1, of compound D
• and reacting Q2 in a second step with
• (f1) from 0.01 to 50% by weight, based on the polyether ester Q2, of hydroxycarboxylic acid B1,
• where the hydroxycarboxylic acid B1 is defined by the formulae IIa or IIb:
• where p is an integer from 1 to 1500 and r is an integer from 1 to 4, and G is a radical which is selected from the group consisting of phenylene, —(CH2)k—, where k is an integer from 1 to 5, —C(R)H— and —C(R)HCH2, where R is methyl or ethyl, and also with
• (f2) 0-5 mol %, based on the molar amount of component (a1) used for preparing P1 and the polyether ester Q2, of compound D.

A process for preparing the biodegradable polymers T3 having a molecular weight (Mn) in the range from 10,000 to 100,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polymer T3 at 25° C.) and a melting point in the range from 50 to 235° C., which comprises preparing in a first step

• (g1) polyether esters P2, obtained by reacting a mixture essentially comprising
• (b1) a mixture essentially comprising:
• 30-70 mol % of adipic acid or ester-forminq derivatives thereof or mixtures thereof,
• 30-70 mol % of terephthalic acid or ester-forming derivatives thereof or mixtures thereof, and
• 0-5 mol % of a compound containing sulfonate groups,
• where the total of the individual mole percentages is 100 mol %,
• (b2) a mixture of dihydroxy compounds (a2), essentially comprising
• (a21) from 15 to 99.8 mol % of a dihydroxy compound selected from the group consisting of C2-C6-alkanediols and C5-C10-cycloalkanediols,
• (a22) from 85 to 0.2 mol % of a dihydroxy compound containing ether functionalities of the formula I:
• HO—((CH2)n—O)m—H I
• where n is 2, 3 or 4 and m is an integer from 2 to 250, or mixtures thereof,
• where the molar ratio of (b1) to (b2) is chosen in the range from 0.4:1 to 1.25:1,
• (b3) from 0.01 to 100% by weight, based on component (b1), of a hydroxycarboxylic acid B1, and
• (b4) from 0 to 5 mol %, based on component (b1), of compound D having at least three groups capable of ester formation,
• where the hydroxycarboxylic acid B1 is defined by the formulae IIa or IIb:
• where p is an integer from 1 to 1500 and r is an integer from 1 to 4, and G is a radical which is selected from the group consisting of phenylene, —(CH2)k—, where k is an integer from 1 to 5, —C(R)H— and —C(R)HCH2, where R is methyl or ethyl,
• where the polyether ester P2 has a molecular weight (Mn) in the range from 5000 to 80,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester P2 at 25° C.) and a melting point in the range from 50 to 235° C., or
• (g2) a mixture essentially comprising polyether ester P1 obtained by reacting a mixture essentially comprising
• (a1) a mixture essentially comprising
• 40-70 mol % of adipic acid or ester-forming derivatives thereof or mixtures thereof,
• 30-60 mol % of terephthalic acid or ester-forming derivatives thereof or mixtures thereof, and
• 0-5 mol % of a compound containing sulfonate groups,
• where the total of the individual mole percentages is 100 mol %, and
• (a2) a mixture of dihydroxy compounds essentially comprising
• (a21) from 15 to 99.8 mol % of a dihydroxy compound selected from the group consisting of C2-C6-alkanediols and C5-C10-cycloalkanediols,
• (a22) from 85 to 0.2 mol % of a dihydroxy compound containing ether functionalities of the formula I:
• HO—((CH2)n—O)m—H I
• where n is 2, 3 or 4 and m is an integer from 2 to 250, or mixtures thereof,
• where the molar ratio of (a1) to (a2) is chosen in the range from 0.4:1 to 1.5:1, with the proviso that the polyether esters P1 have a molecular weight (Mn) in the range from 5000 to 80,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester P1 at 25° C.) and a melting point in the range from 50 to 200° C., and with the further proviso that from 0 to 5 mol %, based on the molar quantity of component (a1) employed, of compound D are employed to prepare the polyether esters P1
• or polyether esters Q2 having a molecular weight (Mn) in the range from 6000 to 80,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester Q2 at 25° C.) and a melting point in the range from 50 to 200° C., obtained by reacting a mixture essentially comprising:
• 30-60 mol % of terephthalic acid or ester-forming derivatives thereof or mixtures thereof, and
• 0-5 mol % of a compound containing sulfonate groups,
• where the total of the individual mole percentages is 100 mol %, and (a2),
• where the molar ratio of (a1) to (a2) is chosen in the range from 0.4:1 to 1.5:1, with the proviso that the polyether esters P1 have a molecular weight (Mn) in the range from 5000 to 80,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester P1 at 25° C.) and a melting point in the range from 50 to 200° C., and with the further proviso that from 0 to 5 mol %, based on the molar quantity of component (a1) employed, of compound D are employed to prepare the polyether esters P1
• and from 0.01 to 50% by weight, based on polyether ester P1, of hydroxycarboxylic acid B1, or
• (g3) a mixture essentially comprising polyether esters P1 which differ from one another in composition,
• and reacting in a second step (g1) or (g2) or (g3)
• with 0.1-5% by weight, based on the quantity of the polyether esters employed, of a diisocyanate C1 and
• with 0-5 mol %, based on the respective molar quantities of component (a1) employed to prepare the polyether esters (g1) to (g3), of compound D.

A process for preparing the biodegradable thermoplastic molding compositions T4, which comprises preparing in a first step

• polyether esters P1 obtained by reacting a mixture essentially comprising:
• (a1) a mixture essentially comprising:
• 40-70 mol % of adipic acid or ester-forminq derivatives thereof or mixtures thereof,
• 30-60 mol % of terephthalic acid or ester-forming derivatives thereof or mixtures thereof, and
• 0-5 mol % of a compound containing sulfonate groups,
• where the total of the individual mole percentages is 100 mol %, and
• (a2) a mixture of dihydroxy compounds essentially comprising
• (a21) from 15 to 99.8 mol % of a dihydroxy compound selected from the group consisting of C2-C6-alkanediols and C5-C10-cycloalkanediols,
• (a22) from 85 to 0.2 mol % of a dihydroxy compound containing ether functionalities of the formula I:
• HO—((CH2)n—O)m—H I
• where n is 2, 3 or 4 and m is an integer from 2 to 250, or mixtures thereof,
• where the molar ratio of (a1) to (a2) is chosen in the range from 0.4:1 to 1.5:1, with the proviso that the polyether esters P1 have a molecular weight (Mn) in the range from 5000 to 80,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester P1 at 25° C.) and a melting point in the range from 50 to 200° C., and with the further proviso that from 0 to 5 mol %, based on the molar quantity of component (a1) employed, of a compound D having at least three groups capable of ester formation are employed to prepare the polyether esters P1
• or polyether esters Q2 having a molecular weight (Mn) in the range from 6000 to 80,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester Q2 at 25° C.) and a melting point in the range from 50 to 200° C., obtained by reacting a mixture essentially comprising
• (d1) from 95 to 99.9% by weight of polyether ester P1
• (d2) from 0.1 to 5% by weight of a diisocyanate C1 and
• (d3) from 0 to 5 mol %, based on component (a1) used for preparing P1, of compound D,
• and, in a second step, mixing from 99.5 to 0.5% by weight of P1 or Q2 with from 0.5 to 99.5% by weight of hydroxycarboxylic acid B1.