USE OF AN ADDITIVE COMPOSITION FOR THE CONTROLLED ACCELERATED DECOMPOSITION OF CONDENSATION POLYMERS

Abstract

The invention relates to the use of a mixture consisting of at least one aliphatic or cycloaliphatic polyol, in particular one adlitol or cyclitol, and at least one organic phosphorus compound under protic conditions as an additive (hydrolysis catalyst) that catalyzes the hydrolysis of condensation polymers. The invention also relates to a condensation polymer composition which contains at least one aliphatic or cycloaliphatic polyol, in particular one adlitol and/or cyclitol, at least one organic phosphorus compound and at least one condensation polymer and is free of a compound according to formula IV, as said compound is defined below. Another aspect of the invention is a molding compound or a molded part that can be produced from the condensation polymer composition according to the invention. Finally, the invention is directed to a method for producing the condensation polymer composition.

Claims

1-21. (canceled)

22. A method of catalyzing hydrolysis of a condensation polymer under protic conditions, comprising adding an additive during formation of the condensation polymer, which consists of a mixture of (A) at least one polyol selected from the group comprising aliphatic or cycloaliphatic polyols, and (B) at least one organic phosphorus compound.

23. The method of claim 22, wherein the additive thermally stabilizes the condensation polymer.

24. The method of claim 22, wherein the condensation polymer is selected from the group consisting of polyesters of aliphatic or aromatic dicarboxylic acids and diols or of hydroxycarboxylic acids, polycarbonates, polyester carbonates, polyamides, semi aromatic polyamides, and mixtures, combinations, or blends of two or more of the above-named polymers.

25. The method of claim 22, wherein the condensation polymer is selected from the group consisting of PLA, poly(butylene adipate) (PBA), polycaprolactone (PCL), poly-3-hydroxybutyrate, poly-4-hydroxybutyrate, poly-3-hydroxyvalerate, poly(hexamethylene succinate), poly(butylene succinate) and copolymers and mixtures or blends of two or more of the above-named polymers.

26. The method of claim 25, wherein the condensation polymer is selected from the group consisting of PLA, PBA, and copolymers thereof.

27. The method of claim 26, wherein the PLA copolymers are obtained by ring-opening polymerization of D-lactide and/or L-lactide with comonomers selected from hydroxycarboxylic acids, diols, and/or carboxylic acids.

28. The method of claim 24, wherein the at least one aliphatic or cycloaliphatic polyol is selected from the group consisting of polyols having at least four OH groups.

29. The method of claim 22, wherein the at least one organic phosphorus compound is selected from the group consisting of organic phosphites, organic phosphonites, organic phosphonates, organic phosphates, and mixtures and combinations thereof.

30. The method of claim 29, wherein the organic phosphite is a hydrolyzable phosphite having the general formula I ##STR00014## wherein (i) R.sup.1, R.sup.2 and R.sup.3 are selected independently of one another from the group consisting of optionally substituted C.sub.4-C.sub.32-alkyl-, cycloalkyl- and aryl residues, or (ii) R.sup.1 is selected from the group consisting of optionally substituted C.sub.4-C.sub.32-alkyl-, cycloalkyl- and aryl residues and R.sup.2 is connected to R.sup.3 to form a cyclic system.

31. The method of claim 29, wherein the organic phosphite has one of the following formulas (II) or (III), ##STR00015## wherein R.sup.1 is selected from optionally substituted C.sub.4-C.sub.32-alkyl-, -cycloalkyl-, and aryl residues.

32. The method of claim 29, wherein the organic phosphite is selected from the following compounds ##STR00016## ##STR00017## ##STR00018## in which n=1-100, or from the group consisting of trilauryl phosphite, triisodecylphosphite, tridecylphosphite, trihexadecylphosphite, trioctadecylphosphite, tribehenylphosphite, triarachidylphosphite, tricerylphosphite, tricetylphosphite, and trioleylphosphite.

33. The method of claim 29, wherein the organic phosphite is free of a compound in accordance with formula (IV) ##STR00019## wherein R.sup.20 and/or R.sup.21 are, independently of one another on every occurrence, a hydrogen atom, a C.sub.1-8-alkyl group, a C.sub.5-8-cycloalkyl group, a C.sub.6-12-alkylcycloalkyl group, a C.sub.7-12-aralkyl group, or a phenyl group, R.sup.23 and R.sup.24 are, independently of one another on every occurrence, a hydrogen atom, a C.sub.1-8-alkyl group, a C.sub.5-8-cycloalkyl group, a C.sub.6-12-alkylcycloalkyl group, a C.sub.7-12-aralkyl group, or a phenyl group, R.sup.22 is a hydrogen atom or an alkyl group on every occurrence, L.sup.5 is a single bond, a sulfur atom, or a bivalent group in accordance with the formula (IVa) ##STR00020## where R.sup.25 signifies a hydrogen atom, a C.sub.1-8-alkyl group, or a C.sub.5-8-cycloalkyl group, L.sup.6 is a C.sub.2-8-alkylene group or a bivalent group in accordance with the formula (IVb) ##STR00021## where L.sup.7 is a single bond or a C.sub.1-8-alkylene group and * represents an oxygen bonding site, and one of Z.sup.1 and Z.sup.2 is a hydroxyl group, a C.sub.1-8-alkyl group, a C.sub.1-8-alkoxy group or a C.sub.7-12-aralkyloxy group, and the other is a hydrogen atom or a C.sub.1-8-alkyl group.

34. The method of claim 29, wherein the organic phosphate is selected from the group consisting of trilauryl phosphate, triisodecyl phosphate, tridecyl phosphate, trihexadecyl phosphate, trioctadecyl phosphate, tribehenyl phosphate, triarachidyl phosphate, triceryl phosphate, tricetyl phosphate, and trioleyl phosphate, diphosphates, polyphosphates, monostearyl phosphate, distearyl phosphate, and mixtures of a monoalkyl phosphate, of a dialkyl phosphate and of a trialkyl phosphate.

35. The method of claim 22, wherein the weight ratio of component (A) to component (B) is from 1:10 to 10:1.

36. A condensation polymer composition comprising: (A) at least one polyol, selected from the group consisting of aliphatic and cycloaliphatic polyols, (B) at least one organic phosphorus compound, and (C) at least one condensation polymer, wherein the composition is free of a compound in accordance with the formula (IV): ##STR00022## wherein R.sup.20 and/or R.sup.21 are, independently of one another on every occurrence, a hydrogen atom, a C.sub.1-8-alkyl group, a C.sub.5-8-cycloalkyl group, a C.sub.6-12-alkylcycloalkyl group, a C.sub.7-12-aralkyl group, or a phenyl group, R.sup.23 and R.sup.24 are, independently of one another on every occurrence, a hydrogen atom, a C.sub.1-8-alkyl group, a C.sub.5-8-cycloalkyl group, a C.sub.6-12-alkylcycloalkyl group, a C.sub.7-12-aralkyl group, or a phenyl group, R.sup.22 is a hydrogen atom or an alkyl group on every occurrence, L.sup.5 is a single bond, a sulfur atom, or a bivalent group in accordance with the formula (IVa) ##STR00023## where R.sup.25 signifies a hydrogen atom, a C.sub.1-8-alkyl group, or a C.sub.5-8-cycloalkyl group, L.sup.6 is a C.sub.2-8-alkylene group or a bivalent group in accordance with the formula (IVb) ##STR00024## where L.sup.7 is a single bond or a C.sub.1-8-alkylene group and * represents an oxygen bonding site, and one of Z.sup.1 and Z.sup.2 is a hydroxyl group, a C.sub.1-8-alkyl group, a C.sub.1-8-alkoxy group or a C.sub.7-12-aralkyloxy group, and the other is a hydrogen atom or a C.sub.1-8-alkyl group.

37. The condensation polymer composition of claim 36, wherein the condensation polymer composition comprises (A) 0.01 to 5.00 parts by weight of at least one polyol, (B) 0.01 to 5.00 parts by weight of the at least one phosphorus compound, and (C) 90.00 to 99.98 parts by weight of a condensation polymer.

38. The condensation polymer composition of claim 36, which comprises, in addition to components (A) to (C), at least one additive that is selected from the group consisting of primary antioxidants, secondary antioxidants, UV absorbers, light stabilizers, metal deactivators, filler deactivators, antiozonants, nucleation agents, anti-nucleation agents, toughening agents, plasticizers, mold lubricants, rheological modifiers, thixotropic agents, chain extenders, processing aids, mold release agents, flame retardants, pigments, dyes, optical brighteners, antimicrobial active agents, antistatic agents, slip agents, anti-blocking agents, coupling agents, crosslinking agents, anti-cross-linking agents, hydrophilization agents, hydrophobing agents, bonding agents, dispersing agents, compatibilizers, oxygen scavengers, acid scavengers, expanding agents, degradation additives, defoaming agents, odor scavengers, marking agents, anti-fogging agents, fillers, reinforcement materials, and mixtures thereof.

39. The condensation polymer composition of claim 36, wherein the plastic composition additionally comprises at least one additive selected from (i) degradation additive, (ii) nucleation agent, (iii) chain extender, and (iv) filler.

40. A method of manufacturing a condensation polymer composition comprising introducing into a condensation polymer a mixture comprising (A) at least one polyol selected from the group comprising aliphatic or cycloaliphatic polyols, and (B) at least one organic phosphorus compound.

41. The method of claim 40, wherein the mixture is introduced into the condensation polymer in that it is first mixed as a solid mixture with the condensation polymer and the mixture resulting therefrom is subsequently melted in an extruder.

42. A molding compound or a molded part produced from a condensation polymer composition of claim 36.

43. A product comprising a molding compound of claim 42, wherein the product is a packaging for foods or cosmetic products, an encapsulating material in pharmaceutical industry, a medical dressing material, a surgical suture material, a hygiene product, or an agricultural film.

Description

[0063] The present invention will be described in more detail with reference to the following examples, but without intending to restrict the invention to the preferred parameters shown.

[0064] Various condensation polymer compositions (VB1-VB4 and B1-B5) were produced.

[0065] Luminy L 130 (≤0.5% D-lactic acid in accordance with the certificate, MVR=8.8 cm.sup.3/10 min, measured at 190° C./2.16 kg stamped weight) of the company of Corbion was used as PLA. The polymers were dried at 80° C. in a vacuum drying cabinet for at least 16 h before processing.

[0066] The compounds listed below were used as the additives: [0067] Ph-a: Songnox 6260 (manufacturer Songwon)

##STR00011## [0068] Ph-b: Doverphos S 9228 (manufacturer Dover)

##STR00012## [0069] Ph-d: mixture of tristearyl phosphate, distearyl phosphate, and monostearyl phosphate, commercial product ADK Stabl AX 71 of the company Adeka. [0070] Al-a: myo-inosite (a cyclitol) [0071] Al-b: dipentaerythritol (an aliphatic polyol) [0072] Al-c: Erythrite (an alditol)

[0073] The manufacture of the condensation polymer compositions (B1-B5) in accordance with the invention and of the comparison examples (VB1-VB4) was accomplished by extrusion using a parallel twin screw extruder “Process 11” of the company Thermo Scientific, having a screw diameter of 11 mm and a length to diameter ratio (LD) of 40.

[0074] The additives were manually mixed with the matrix polymer in a plastic bag and were volumetrically metered for the compositions VB2-VB4 and B1-B5. The processing was carried out at a throughput of 1 kg/h and a screw speed of 200 r.p.m. at 200° C.

[0075] To check the hydrolysis rate, the polymer was stored in water as pellets at 58° C. and the MVR was determined after 42 or 162 h, respectively. The measurement of the MVR was carried out on a melt index test unit MI-2 of the company Göttfert at a test temperature of 190° C. and a stamp weight of 2.16 kg. The samples were dried for at least 16 h in the vacuum furnace at 80° C. prior to the measurement. The preheating time amounted to 4 minutes. The MVR is indicated in cm.sup.3/10 min.

[0076] The results of the processing tests are summarized in Table 1 and of the hydrolysis experiments in Table 2.

TABLE-US-00001 TABLE 1 Processing stability of PLA compositions MVR increase in the extrusion (with respect to Phosphorus zero values of comparison compound Alditol trials VB1) Type Wt. % Type Wt. % (Extrusion) VB1 — — — — 0.6 (with respect to MVR starting material 8.8 cm.sup.3/10 min, averaged value of 3 trials) VB2 Ph-a 0.25 — — 0.9 VB3 Ph-a 0.50 1.6 VB4 Ph-b 0.50 — — 2.5 VB5 Ph-d 0.25 5.2 VB6 — — Al-a 0.50 0.1 VB7 Al-b 0.50 1.1 B1 Ph-a 0.25 Al-a 0.50 0.4 B2 Ph-a 0.25 Al-b 0.50 1.6 B3 Ph-a 0.50 Al-a 0.05 0.4 B4 Ph-a 0.50 Al-c 0.05 0.5 B5 Ph-b 0.50 Al-c 0.05 1.5 B6 Ph-d 0.25 Al-a 0.50 3.6

[0077] As can be seen from the tests for processing stability, the addition of a phosphite or phosphate results in an increase in the MVR, that is to an unwanted degradation of the polymer. This degradation during processing can be reduced by the combination in accordance with the invention.

TABLE-US-00002 TABLE 2 Water storage of PLA compositions Phosphorus MVR increase MVR increase compound Alditol after water after water Type Wt. % Type Wt. % storage at 42 h. storage at 162 h VB1 — — — — 11 ND VB2 Ph-a 0.25 — — 24 ND VB3 Ph-a 0.50 ND ND VB4 Ph-b 0.50 — — 31 h (47 h) ND VB5 Ph-d 0.25 26 ND VB6 — — Al-a 0.50 7.6 124 VB7 Al-b 0.50 9.6  85 B1 Ph-a 0.25 Al-a 0.50 24 128 B2 Ph-a 0.25 Al-b 0.50 26 176 B3 Ph-a 0.50 Al-a 0.05 36 h (47 h) ND B4 Ph-a 0.50 Al-c 0.05 42 h (47 h) ND B5 Ph-b 0.50 Al-c 0.05 32 h (47 h) ND B6 Ph-d 0.25 Al-a 0.50 28 320 ND = Not determined

[0078] A degradation of the polymer occurs during water storage starting from a higher molecular weight (lower MVR) due to the improved processing stability of the compositions in accordance with the invention. It should thus be assumed that the degradation during water storage is also delayed (which is documented by the sole addition of alditols) since a higher number of chain scissions is required for a specific lower molecular weight. The degradation is surprisingly not delayed by the compositions in accordance with the invention, but rather remains at least the same or is even accelerated.

[0079] In a further series of experiments, Luminy L 175 (≤0.5% D-lactic acid in accordance with the certificate, MVR=4.7 cm.sup.3/10 min, measured at 190° C./2.16 kg stamp weight) supplied by Corbion was used as PLA.

Ph-c: Weston 618F (Supplier: SI Group)

[0080] ##STR00013##

Ph-d: Adekastab AX-71 (see above)
Al-d: sorbite (an alditol)

[0081] The results of the processing tests and of the hydrolysis tests are summarized in Table 3.

TABLE-US-00003 TABLE 3 MVR MVR MVR [190/2.16] [190/2.16] [190/2.16] MVR after after after Phosphorus [190/2.16] water water water compound Alditol after storage storage storage Type Wt. % Type Wt. % extrusion at 48 h at 96 h at 168 h VB8 — — — — 6.0 14.9 26 69 C1 Ph-d 0.1 Al-d 0.40 6.4 17 39 12 C2 Ph-d 0.25 Al-d 0.25 7.6 22 35 145 C3 Ph-d 0.40 Al-d 0.10 6.8 24 58 230 C4 Ph-c 0.1 Al-d 0.4 6.1 19 35 89 C5 Ph-c 0.25 Al-d 0.25 6.3 28 57 210 C6 Ph-c 0.4 Al-d 0.1 6.8 41 105 >>300

[0082] The compositions in accordance with the invention only show a small increase of the MVR value after extrusion and an accelerated degradation during water storage, documented by a higher MVR value, i.e., a lower molecular weight, in comparison with the test without additive. The acceleration of the degradation can be monitored and set by the ratio of polyol and phosphorus, with a higher proportion of polyol contributing to the processing stability and a higher proportion of a phosphorus component contributing to the accelerated degradation.