METHOD FOR THE PRODUCTION OF A POLYESTER CARBONATE

Abstract

The present invention relates to a method for producing an aliphatic polyester carbonate, the polyester carbonate itself, and to moulding compositions and moulded articles containing the polyester carbonate. The claimed method is characterised in particular in that the method comprises three steps and the last step is a melt transesterification method in the presence of two catalysts.

Claims

1.-15. (canceled)

16. A process for preparing a polyester carbonate comprising the steps of: (i) reacting a mixture comprising at least one linear aliphatic dicarboxylic acid and/or at least one cycloaliphatic dicarboxylic acid and at least one aliphatic and/or aromatic carbonate, in the presence of at least one first catalyst that is basic, to form an aliphatic diester of formula (1) ##STR00018##  in which  A in each case independently represents an aliphatic or aromatic radical,  D represents R.sub.3 or one of formulas (1a) or (1b), where R.sub.3 represents a linear alkylene group having 3 to 16 carbon atoms and this alkylene group may optionally be mono- or polysubstituted or ##STR00019##  in which  B in each case independently represents a CH.sub.2 group, O or S,  R.sub.1 in each case independently represents a single bond or an alkylene group having 1 to 10 carbon atoms and  R.sub.2 in each case independently represents an alkyl group having 1 to 10 carbon atoms,  n is a number between 0 and 3,  m is a number between 0 and 6 and “*” indicate the positions at which the  —(C═O)OA groups in formula (1) are present,  (ii) separating the aliphatic diester of formula (1) from the mixture from process step (i),  (iii) reacting the separated aliphatic diester of formula (1), at least one dihydroxy compound, and at least one diaryl carbonate in a melt transesterification process in the presence of a mixture comprising a second catalyst and a third catalyst, wherein the second catalyst is a tertiary nitrogen base, wherein the third catalyst is a basic alkali metal salt, and wherein the proportion of alkali metal cations in process step (iii) is 0.0010% to 0.0030% by weight based on all components used in process step (iii).

17. The process as claimed in claim 16, wherein B in formulas (Ia) and (Ib) represents a CH.sub.2 group.

18. The process as claimed in claim 17, wherein the cycloaliphatic dicarboxylic acid is selected from the group consisting of cyclohexane-1,4-dicarboxylic acid, cyclohexane-1,3-dicarboxylic acid, cyclohexane-1,2-dicarboxylic acid, and hydrogenated dimer fatty acid and mixtures of these aliphatic dicarboxylic acids.

19. The process as claimed in claim 16, wherein, in process step (i), an aromatic carbonate of formula (III) is used ##STR00020## where R, R′, and R″ may each independently be identical or different and represent hydrogen, optionally branched C1-C34 alkyl, C7-C34 alkylaryl or C6-C34 aryl; in addition R may also denote —COO—R″′, where R″′ represents optionally branched C1-C34 alkyl, C7-C34 alkylaryl or C6-C34 aryl.

20. The process as claimed in claim 16, wherein the first catalyst used in process step (i) is selected from the group consisting of cesium carbonate, sodium phenoxide, and 4-dimethylamine pyridine and mixtures of these substances.

21. The process as claimed in claim 16, wherein the first catalyst used in process step (i) is used in an amount of from 0.005% to 0.2% by weight based on all of the components used in process step (i).

22. The process as claimed in claim 16, wherein the second catalyst used in process step (iii) is used in an amount of from 0.005% to 0.02% by weight based on all components used in process step (iii).

23. The process as claimed in claim 16, wherein the second catalyst used in process step (iii) is selected from the group consisting of bases derived from guanidine, 4-dimethylaminopyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene, and 1,5-diazabicyclo[4.3.0]non-5-ene and mixtures of these substances.

24. The process as claimed in a claim 16, wherein the alkali metal cations in process step (iii) are selected from sodium cations, lithium ions, cesium cations, and mixtures thereof.

25. The process as claimed in claim 24, wherein the third catalyst used in process step (iii) is selected from the group consisting of sodium hydroxide, lithium hydroxide, sodium phenoxide, lithium phenoxide, sodium benzoate, lithium benzoate, and cesium carbonate and mixtures of these substances.

26. The process as claimed in claim 16, wherein the dihydroxy compound in process step (iii) is selected from the group consisting of cyclohexane-1,2-diol, cyclohexane-1,3-diol, cyclohexane-1,4-diol, cyclohexane-1,2-dimethanol, cyclohexane-1,3-dimethanol, cyclohexane-1,4-dimethanol, tricyclodecanedimethanol, 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, 2,2-bis(4-hydroxycyclohexyl)propane, tetrahydrofuran-2,5-dimethanol, bisphenol A, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 4,4′-dihydroxybiphenyl (DOD), 4,4′-dihydroxydiphenyl ether (DOD ether), bisphenol B, bisphenol M, the bisphenols (V) to (VII) ##STR00021## where in formulas (V) to (VII) R′ in each case represents C.sub.1-C.sub.4 alkyl, aralkyl or aryl.

27. The process as claimed in claim 26, wherein the dihydroxy compound in process step (iii) is selected from the group consisting of isomannide, isoidide, and isosorbide and mixtures thereof.

28. A polyester carbonate obtainable by the process as claimed in claim 16.

29. A molding compound comprising a polyester carbonate as claimed in claim 28.

30. A molding comprising a polyester carbonate as claimed in claim 28.

Description

EXAMPLES

Materials Used

[0169] Cyclohexane-1,4-dicarboxylic acid: CAS 1076-97-7; purity 99%; Tokyo Chemical Industries, Japan

[0170] Diphenyl carbonate: Purity≥99.5%; CAS 102-09-0; Covestro NV, Antwerp, Belgium

[0171] Sodium phenoxide trihydrate: Purity 98%; CAS 652-67-5; Merck, Darmstadt, Germany

[0172] Isosorbide: CAS 652-67-5; Polysorb PSA; Roquette Frères, France

[0173] 4-Dimethylaminopyridine: Purity≥98.0%; CAS 1122-58-3; Sigma-Aldrich, Munich, Germany

[0174] Cesium carbonate: Purity≥99.0%; CAS 534-17-8; Sigma-Aldrich, Munich, Germany

Analytical Methods

[0175] Determination of solution viscosity: The relative solution viscosity (rel; also referred to as eta rel) was determined for a 1% by weight dichloromethane solution of the polyester carbonate versus dichloromethane at 25° C. using an Ubbelohde viscometer. The determination was carried out in accordance with DIN 51562-3; 1985-05. In this determination, the transit times of the polyester carbonate under investigation are measured by the Ubbelohde viscometer in order to then determine the difference in viscosity between the polymer solution and its solvent. For this, the Ubbelohde viscometer undergoes an initial calibration through measurement of the pure solvents dichloromethane, trichloroethylene, and tetrachloroethylene (always performing at least 3 measurements, but not more than 9 measurements). This is followed by the calibration proper with the solvent dichloromethane. The polymer sample is then weighed out, dissolved in dichloromethane and the flow time for this solution then determined in triplicate. The average of the flow times is corrected via the Hagenbach correction and the relative solution viscosity calculated.

[0176] Visual examination: The color and transparency of the polyester carbonate were assessed visually.

[0177] Purity of the diphenyl cyclohexane-1,4-dicarboxylate: The purity of the diphenyl cyclohexane-1,4-dicarboxylate was determined by gas chromatography with flame ionization detector (GC-FID).

Example 1a—Preparation of Diphenyl cyclohexane-1,4-dicarboxylate and Separation, Process Steps (i) and (ii)

[0178] A 6-liter flask with distillation bridge, distillate collecting flask, and vacuum pump with cold trap was charged with 3156.28 g of diphenyl carbonate, 1208.04 g of cyclohexane-1,4-dicarboxylic acid, and 2.619 g of sodium phenoxide trihydrate and the mixture heated at 180° C. with stirring. The pressure was left at standard pressure. At 180° C. the initial evolution of CO.sub.2 was observed. The CO.sub.2 was continuously withdrawn from the flask while heating the reaction mixture to 200° C. over a 15-minute period and to 210° C. over a further 45-minute period. The reaction mixture was left at 210° C. for a further 135 minutes. Phenol was then removed from the reaction mixture by distillation under reduced pressure. Over a 60-minute period, at an overhead temperature of 170° C., the pressure was lowered from 700 mbar to 12 mbar, thereby ensuring steady removal of the phenol from the reaction mixture.

[0179] After the distillation under reduced pressure, 2285 g of reaction product remained in the flask. After cooling, the reaction product was dissolved in toluene (2 g of toluene per 1 g of reaction product) at 80° C. and the reaction product was recrystallized by cooling. Drying in a vacuum oven afforded 1332 g of diphenyl cyclohexane-1,4-dicarboxylate as a white powder. GC-FID analysis revealed a purity of 99.8% trans-diphenyl cyclohexane-1,4-dicarboxylate. The toluene containing secondary components was cooled to −18° C., resulting in the crystallization of a further 489 grams of product, which was separated off as a white solid.

Example 1b: Polymerization of Isosorbide, Diphenyl Carbonate, and Diphenyl cyclohexane-1,4-dicarboxylate, Process Step (iii)

[0180] A three-necked flask with stirrer (from IKA), oil bath, short-path separator, vacuum connection, and cold trap was charged with 59.96 g of isosorbide, 51.73 g of diphenyl carbonate, and 57.04 g of diphenyl cyclohexane-1,4-dicarboxylate obtained from process step 1a.

[0181] Solutions of the appropriate catalysts in phenol were added to the initial charge. The catalyst solutions in each case consisted of 5% by weight of catalyst and 95% by weight of phenol. N,N-Dimethylaminopyridine was added to the reactants in the initial charge in an absolute content of 0.0090 g. This corresponds to 53.3 ppm (by weight) of catalyst based on the reactants used or 6.1 ppm (by weight) of nitrogen based on the reactants used.

[0182] Sodium phenoxide trihydrate was added to the reactants in the initial charge in an absolute content of 0.0225 g. This corresponds to 133.3 ppm by weight based on the reactants used or 18.0 ppm by weight of alkali metal based on the reactants used.

[0183] The reaction mixture was freed of oxygen by evacuating and releasing the vacuum with nitrogen three times and then melted at 170° C. and standard pressure until a homogeneous melt was present. The temperature of the reaction mixture was then increased to 180° C., the pressure cautiously lowered to 200 mbar, and the reaction mixture held at these parameters for 20 minutes. The temperature of the reaction mixture was then increased to 220° C., the pressure lowered to 50 mbar, and the stirring speed of the stirrer reduced. After a further 20-minute hold time, the pressure was lowered to 25 mbar and the stirring speed of the stirrer further reduced. After a further 15-minute hold time, the temperature of the reaction mixture was increased to 230° C. and the pressure lowered to 0.59 mbar. After a further 5-minute hold time, the temperature of the reaction mixture was increased to 240° C. and this was in turn held for 10 minutes. The vacuum was then released by introducing nitrogen and a sample of the product was taken from the flask.

[0184] A transparent product resulted. Visual examination revealed a slight yellow tinge. The relative solution viscosity was 1.22.

[0185] The polymerization of isosorbide, diphenyl carbonate, and diphenyl cyclohexane-1,4-dicarboxylate in examples 2b to 13b below was carried out in analogous manner to example 1b. In these experiments, the number of catalysts and their proportion by weight in ppm based on the amount of reactants used in this process step (iii) were varied. Details are shown in Table 1 below. The stated proportions by weight are in each case in ppm.

TABLE-US-00001 TABLE 1 Varying the catalysts in process step (iii) Experiment Cs.sub.2CO.sub.3 DMAP NaOPh•3H.sub.2O Alkali metal No. [ppm] [ppm] [ppm] [ppm] Eta rel Observations 2b non-inv. 0 53.3 26.7 3.6 1.16 light-colored and transparent product, brittle 3b non-inv. 0 53.3 53.3 7.2 1.16 light-colored and transparent product, brittle 4b inv. 0 53.3 80.0 10.8 1.21 light-colored and transparent product, not brittle 5b inv. 0 53.3 106.6 14.4 1.22 light-colored and transparent product, not brittle 1b inv. 0 53.3 133.3 18.0 1.22 light-colored and transparent product, not brittle 6b inv. 0 53.3 186.6 25.2 1.20 light-colored and transparent product, not brittle 7b non-inv. 0 53.3 266.6 36.0 1.36 opaque and brown-colored product 8b non-inv. 0 0 133.3 18.0 — no polymerization 9b non-inv. 2.0 0 0 1.6 — no polymerization 10b  non-inv. 133.3 0 0 108.7 — no polymerization 11b  non-inv. 667 0 0 544.1 — insoluble, brittle, and black-colored product 12b  non-inv. 0 0 667 90.1 — insoluble, brittle, and black-colored product 13b  non-inv. 0 667 0 0 1.05 transparent and very brittle product inv.—example in accordance with the invention non-inv.—example not in accordance with the invention

[0186] The data in Table 1 show that the object of the invention can be achieved only with the claimed process. If the amount of alkali metal in process step (iii) is too small (examples 2b and 3b), only inadequate polymer growth occurs. If the amount is too large (example 7b), this results in a polyester carbonate of inadequate quality.

[0187] If only one catalyst is used, no polymerization to the polyester carbonate occurs or a product of poor quality is obtained (examples 8b to 13b). It is also not possible to obtain a polyester carbonate with good properties by varying the amount of this one catalyst.